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1

E-Print Network 3.0 - addressing cancer clusters Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

addressing cancer clusters Search Powered by Explorit Topic List Advanced Search Sample search results for: addressing cancer clusters Page: << < 1 2 3 4 5 > >> 1 THE PUBLIC HEALTH...

2

Four stage, fluidized bed gasification process minimizes NO{sub x}  

SciTech Connect (OSTI)

In 1981, after a long and thorough study of alternative methods of sewage sludge (biosolids) disposal, the City of Los Angeles (CLA) embarked on a pilot test program to incinerate dried sewage sludge from its Hyperion Wastewater Treatment Plant. This dried sludge is typically 47% ash, 53% combustible, and has an average higher heating value (HHV), moisture, ash-free (MAF) of 10,675 Btu/Lbm. The dried sludge is called sludge derived fuel (SDF). Approximately 8% of the MAF fraction of SDF is fuel-bound nitrogen. When SDF, with its extremely high fuel-bound nitrogen, was combusted in conventional multiple hearth and fluidized bed pilot plant furnaces, NO{sub x} emissions were extremely high ({gt}1,000 ppm). Faced with this dilemma, the CLA initiated an R and D program to reduce NO{sub x}. The pilot tests with a sub-stoichiometric fluid bed and an excess air afterburner (two-stages) reduced NO{sub x} to 400--600 ppm. With one intermediate stage added (three-stage), NO{sub x} was reduced to 130--150 ppm. However, when the following four-stage process was developed and tested, NO{sub x} was reduced to 50--75 ppm. Stage 1: Sub-stoichiometric fluidized bed operating at a nominal 30% stoichiometric air (SA). Stage 2:Sub-stoichiometric zone operating at a nominal 80% SA. Stage 3: Stoichiometric zone operating at a nominal 100% SA. Stage 4: Excess air zone (Afterburner) operating at a nominal 135% SA (35% excess air). After pilot testing was complete and design parameters established, three full-size, fluid bed gasifiers (two operational--one standby) were designed, constructed and operated until 1996. This paper describes the design, operation, and emission testing of these four-stage fluid bed gasifiers with special emphasis on the problems of (a) pneumatic feeding of SDF powder into the pressurized bed and (b) baghouse fabrics (expanded PTEE membrane on PTFE scrim). Final emission test results for NO{sub x} and other criteria pollutants are also presented.

Lewis, F.M.; Haug, R.T.

1999-07-01T23:59:59.000Z

3

Chemical Enrichment RGS cluster sample (CHEERS): Constraints on turbulence  

E-Print Network [OSTI]

Feedback from AGN, galactic mergers, and sloshing are thought to give rise to turbulence, which may prevent cooling in clusters. We aim to measure the turbulence in clusters of galaxies and compare the measurements to some of their structural and evolutionary properties. It is possible to measure the turbulence of the hot gas in clusters by estimating the velocity widths of their X-ray emission lines. The RGS Spectrometers aboard XMM-Newton are currently the only instruments provided with sufficient effective area and spectral resolution in this energy domain. We benefited from excellent 1.6Ms new data provided by the CHEERS project. The new observations improve the quality of the archival data and allow us to place constraints for some clusters, which were not accessible in previous work. One-half of the sample shows upper limits on turbulence less than 500km/s. For several sources, our data are consistent with relatively strong turbulence with upper limits on the velocity widths that are larger than 1000km/...

Pinto, Ciro; Werner, Norbert; de Plaa, Jelle; Fabian, Andrew C; Zhang, Yu-Ying; Kaastra, Jelle S; Finoguenov, Alexis; Ahoranta, Jussi

2015-01-01T23:59:59.000Z

4

The Bologna Open Cluster Chemical Evolution (BOCCE) Project: midterm results from the photometric sample  

E-Print Network [OSTI]

We describe a long term project aimed at deriving information on the chemical evolution of the Galactic disk from a large sample of open clusters. The main property of this project is that all clusters are analyzed in a homogeneous way, to guarantee the robustness of the ranking in age, distance and metallicity. Special emphasis is devoted to the evolution of the earliest phases of the Galactic disk evolution, where clusters have superior reliability with respect to other types of evolution indicators. The project is twofold: on the one hand we derive age, distance and reddening (and indicative metallicity) interpreting deep and accurate photometric data with stellar evolution models, and, on the other hand, we derive the chemical abundances from high-resolution spectroscopy. Here we describe our overall goals and approaches, and report on the mid-term project status of the photometric part, with 16 clusters already studied, covering an age interval from 0.1 to 6 Gyr and Galactocentric distances from 6.6 to 21 kpc. The importance of quantifying the theoretical uncertainties by deriving the cluster parameters with various sets of stellar models is emphasized. Stellar evolution models assuming overshooting from convective regions appear to better reproduce the photometric properties of the cluster stars. The examined clusters show a clear metallicity dependence on the Galactocentric distance and no dependence on age. The tight relation between cluster age and magnitude difference between the main sequence turn off and the red clump is confirmed.

Angela Bragaglia; Monica Tosi

2005-11-01T23:59:59.000Z

5

Studies of the mechanism of the cluster formation in a thermally sampling atmospheric pressure ionization mass spectrometer  

SciTech Connect (OSTI)

In this study a thermally sampling atmospheric pressure ionization mass spectrometer is described and characterized. The ion transfer stage offers the capability to sample cluster ions at thermal equilibrium and during this transfer fundamental processes possibly affecting the cluster distribution are also readily identified. Additionally, the transfer stage combines optional collision-induced dissociation (CID) analysis of the cluster composition with thermal equilibrium sampling of clusters. The performance of the setup is demonstrated with regard to the proton-bound water cluster system. The benefit of the studied processes is that they can help to improve future transfer stages and to understand cluster ion reactions in ion mobility tubes and high-pressure ion sources. In addition, the instrument allows for the identification of fragmentation and protonation reactions caused by CID.

Albrecht, Sascha, E-mail: s.albrecht@fz-juelich.de; Stroh, Fred, E-mail: f.stroh@fz-juelich.de [Forschungszentrum Jülich GmbH, Institute of Energy and Climate Research, Stratosphere (IEK-7), 52428 Jülich (Germany)] [Forschungszentrum Jülich GmbH, Institute of Energy and Climate Research, Stratosphere (IEK-7), 52428 Jülich (Germany); Klopotowski, Sebastian, E-mail: s.klopotowski@uni-wuppertal.de; Derpmann, Valerie, E-mail: v.derpmann@uni-wuppertal.de; Klee, Sonja, E-mail: s.klee@uni-wuppertal.de; Brockmann, Klaus J., E-mail: brockma@uni-wuppertal.de; Benter, Thorsten, E-mail: tbenter@uni-wuppertal.de [Physical and Theoretical Chemistry, Institute for Pure and Applied Mass Spectrometry, University of Wuppertal, 42097 Wuppertal (Germany)] [Physical and Theoretical Chemistry, Institute for Pure and Applied Mass Spectrometry, University of Wuppertal, 42097 Wuppertal (Germany)

2014-01-15T23:59:59.000Z

6

E-Print Network 3.0 - association studies clustering Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

of Three Document Clustering Algorithms: TreeCluster, Summary: with the TreeCluster algorithm. Usability studies will also shed light on what methods cater to user preferences......

7

E-Print Network 3.0 - all-ferrous rieske cluster Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

have shed light on the location of the manganese cluster -- or oxygen... -evolving cluster -- and provided a coarse view of it32,33 . Recently, a higher resolution...

8

E-Print Network 3.0 - alpha cluster states Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

of Wireless Sensor Networks via Unequal Clustering Summary: head is similar. IV NETWORK MODEL As stated previously, the positions of the cluster head nodes... section to...

9

Cosmological Implications and Physical Properties of an X-Ray Flux-Limited Sample of Galaxy Clusters  

E-Print Network [OSTI]

The original abstract significantly exceeds the space available here, so here's a brief summary. The abstract is similar to the abstract of astro-ph/0111285 (ApJ, 567, 716) which describes the X-ray galaxy cluster sample HIFLUGCS, the X-ray luminosity--gravitational mass relation, the cluster mass function, and the derived cosmological constraints. Additionally, the fraction of the total gravitating mass in the universe which is contained in intracluster gas is quantified. Furthermore, physical properties of the cluster sample have been studied and analyses of relations between different cluster parameters (including the gas mass fraction, gas temperature, X-ray luminosity, gas mass, gravitational mass, beta, and core radius) are discussed. Also, results from an analysis of XMM-Newton performance verification phase data of Abell 1835 are described.

Thomas H. Reiprich

2003-08-08T23:59:59.000Z

10

Closing the gap: an X-ray selected sample of clusters of galaxies behind the Galactic plane  

E-Print Network [OSTI]

We discuss the design and current status of the CIZA survey, the first systematic X-ray search for clusters of galaxies in the Galactic plane region. So far, we have compiled a sample of more than 70 X-ray selected clusters at |b|<20 deg, 80% of which were previously unknown. Upon its completion the CIZA cluster catalogue will complement the existing galaxy surveys in the Galactic plane region and allow a fresh look at large-scale structure and local streaming motions.

Harald Ebeling; Christopher Mullis; Brent Tully

2000-01-18T23:59:59.000Z

11

The clustering of ALFALFA galaxies: dependence on HI mass, relationship to optical samples & clues on host halo properties  

E-Print Network [OSTI]

We use a sample of ~6000 galaxies detected by the Arecibo Legacy Fast ALFA (ALFALFA) 21cm survey, to measure the clustering properties of HI-selected galaxies. We find no convincing evidence for a dependence of clustering on the galactic atomic hydrogen (HI) mass, over the range M_HI ~ 10^{8.5} - 10^{10.5} M_sun. We show that previously reported results of weaker clustering for low-HI mass galaxies are probably due to finite-volume effects. In addition, we compare the clustering of ALFALFA galaxies with optically selected samples drawn from the Sloan Digital Sky Survey (SDSS). We find that HI-selected galaxies cluster more weakly than even relatively optically faint galaxies, when no color selection is applied. Conversely, when SDSS galaxies are split based on their color, we find that the correlation function of blue optical galaxies is practically indistinguishable from that of HI-selected galaxies. At the same time, SDSS galaxies with red colors are found to cluster significantly more than HI-selected gala...

Papastergis, Emmanouil; Haynes, Martha P; Rodríguez-Puebla, Aldo; Jones, Michael G

2013-01-01T23:59:59.000Z

12

E-Print Network 3.0 - atomic clusters rb12 Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

, these metal-carbon clusters were proved to be very reactive. 40 60 80 100 Number of Carbon Atoms Intensity... Laser vaporization clusters from metal loaded graphite used for...

13

JOINT ANALYSIS OF CLUSTER OBSERVATIONS. II. CHANDRA/XMM-NEWTON X-RAY AND WEAK LENSING SCALING RELATIONS FOR A SAMPLE OF 50 RICH CLUSTERS OF GALAXIES  

SciTech Connect (OSTI)

We present a study of multiwavelength X-ray and weak lensing scaling relations for a sample of 50 clusters of galaxies. Our analysis combines Chandra and XMM-Newton data using an energy-dependent cross-calibration. After considering a number of scaling relations, we find that gas mass is the most robust estimator of weak lensing mass, yielding 15% {+-} 6% intrinsic scatter at r{sub 500}{sup WL} (the pseudo-pressure Y{sub X} yields a consistent scatter of 22% {+-} 5%). The scatter does not change when measured within a fixed physical radius of 1 Mpc. Clusters with small brightest cluster galaxy (BCG) to X-ray peak offsets constitute a very regular population whose members have the same gas mass fractions and whose even smaller (<10%) deviations from regularity can be ascribed to line of sight geometrical effects alone. Cool-core clusters, while a somewhat different population, also show the same (<10%) scatter in the gas mass-lensing mass relation. There is a good correlation and a hint of bimodality in the plane defined by BCG offset and central entropy (or central cooling time). The pseudo-pressure Y{sub X} does not discriminate between the more relaxed and less relaxed populations, making it perhaps the more even-handed mass proxy for surveys. Overall, hydrostatic masses underestimate weak lensing masses by 10% on the average at r{sub 500}{sup WL}; but cool-core clusters are consistent with no bias, while non-cool-core clusters have a large and constant 15%-20% bias between r{sub 2500}{sup WL} and r{sub 500}{sup WL}, in agreement with N-body simulations incorporating unthermalized gas. For non-cool-core clusters, the bias correlates well with BCG ellipticity. We also examine centroid shift variance and power ratios to quantify substructure; these quantities do not correlate with residuals in the scaling relations. Individual clusters have for the most part forgotten the source of their departures from self-similarity.

Mahdavi, Andisheh [Department of Physics and Astronomy, San Francisco State University, San Francisco, CA 94131 (United States); Hoekstra, Henk [Leiden Observatory, Leiden University, Niels Bohrweg 2, NL-2333 CA Leiden (Netherlands); Babul, Arif; Bildfell, Chris [Department of Physics and Astronomy, University of Victoria, Victoria, BC V8W 3P6 (Canada); Jeltema, Tesla [Santa Cruz Institute for Particle Physics, UC Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States); Henry, J. Patrick [Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)

2013-04-20T23:59:59.000Z

14

E-Print Network 3.0 - american history cluster Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

about people's age, gender, education, job history... , spending patterns, debts, medical history, etc. Clustering could be applied to the database to find groups... Meta...

15

E-Print Network 3.0 - ab initio cluster Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Summary: potentials reproduce the ab initio data surprisingly well, for both the neutral and anionic clusters... . For the pentamers, however, only the polarizable models...

16

E-Print Network 3.0 - alter salt-induced clusterization Sample...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

A Late Fusion Approach Using Latent Models Eric Bruno Viper group, Computer... .Marchand-Maillet@unige.ch ABSTRACT Multi-view clustering is an important problem in informa-...

17

E-Print Network 3.0 - aluminium cluster al4h6 Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

An advanced diffusion model to identify emergent research issues: the case of optoelectronic devices Summary: is a diachronic cluster analysis. With the diffusion model we...

18

E-Print Network 3.0 - algebraic cluster model Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Zurich, October 2007 Motivation ... Source: Baur, Karin - Department of Mathematics, ETH Zurich Collection: Mathematics 3 On generalized cluster categories Claire Amiot...

19

E-Print Network 3.0 - aromatic metal clusters Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Cluster investigation were no different from levels... elevated levels of arsenic, tungsten and six additional metals as well as six nonpersistent pesticides... County Leukemia...

20

E-Print Network 3.0 - au cluster properties Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

A: Chemical 167 (2001) 191198 The nucleation and growth of gold on silica Summary: sublimation energy as a function of Au coverage by leading edge analysis. cluster...

Note: This page contains sample records for the topic "four-stage cluster sampling" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

E-Print Network 3.0 - advaned technology cluster Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Politcnica de Catalunya Collection: Computer Technologies and Information Sciences 4 Fuzzy and Probabilistic Clustering with Shape and Size Constraints Summary: Fuzzy and...

22

The Spatial Clustering of ROSAT All-Sky Survey AGNs III. Expanded Sample and Comparison with Optical AGNs  

E-Print Network [OSTI]

This is the third paper in a series that reports on our investigation of the clustering properties of AGNs identified in the ROSAT All-Sky Survey (RASS) and Sloan Digital Sky Survey (SDSS). In this paper, we extend the redshift range to 0.07clustering amplitudes of both X-ray and optically-selected SDSS broad-line AGNs with and without radio detections as well as for X-ray selected narrow-line RASS/SDSS AGNs. We measure the clustering amplitude through cross-correlation functions (CCFs) with SDSS galaxies and derive the bias by applying a halo occupation distribution (HOD) model directly to the CCFs. We find no statistically convincing difference in the clustering of X-ray and optically-selected broad-line AGNs, as well as with samples in which radio-detected AGNs are excluded. This is in contrast to low redshift optically-selected narrow-line AGNs, where radio-loud AGNs are found in more massive halos than optical AGNs without a radio-detection. The typical dark matter halo mass...

Krumpe, Mirko; Coil, Alison L; Aceves, Hector

2011-01-01T23:59:59.000Z

23

SUNYAEV-ZEL'DOVICH-MEASURED PRESSURE PROFILES FROM THE BOLOCAM X-RAY/SZ GALAXY CLUSTER SAMPLE  

SciTech Connect (OSTI)

We describe Sunyaev-Zel'dovich (SZ) effect measurements and analysis of the intracluster medium (ICM) pressure profiles of a set of 45 massive galaxy clusters imaged using Bolocam at the Caltech Submillimeter Observatory. We deproject the average pressure profile of our sample into 13 logarithmically spaced radial bins between 0.07R{sub 500} and 3.5R{sub 500}, and we find that a generalized Navarro, Frenk, and White (gNFW) profile describes our data with sufficient goodness-of-fit and best-fit parameters (C{sub 500}, {alpha}, {beta}, {gamma}, P{sub 0} = 1.18, 0.86, 3.67, 0.67, 4.29). We use X-ray data to define cool-core and disturbed subsamples of clusters, and we constrain the average pressure profiles of each of these subsamples. We find that, given the precision of our data, the average pressure profiles of disturbed and cool-core clusters are consistent with one another at R {approx}> 0.15R{sub 500}, with cool-core systems showing indications of higher pressure at R {approx}< 0.15R{sub 500}. In addition, for the first time, we place simultaneous constraints on the mass scaling of cluster pressure profiles, their ensemble mean profile, and their radius-dependent intrinsic scatter between 0.1R{sub 500} and 2.0R{sub 500}. The scatter among profiles is minimized at radii between {approx_equal} 0.2R{sub 500} and {approx_equal} 0.5R{sub 500}, with a value of {approx_equal} 20%. These results for the intrinsic scatter are largely consistent with previous analyses, most of which have relied heavily on X-ray derived pressures of clusters at significantly lower masses and redshifts compared to our sample. Therefore, our data provide further evidence that cluster pressure profiles are largely universal with scatter of {approx_equal} 20%-40% about the universal profile over a wide range of masses and redshifts.

Sayers, J.; Czakon, N. G.; Golwala, S. R.; Downes, T. P.; Mroczkowski, T.; Siegel, S. [Division of Physics, Math, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Mantz, A. [Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Ameglio, S.; Pierpaoli, E.; Shitanishi, J. A. [University of Southern California, Los Angeles, CA 90089 (United States); Koch, P. M.; Lin, K.-Y.; Umetsu, K. [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China); Maughan, B. J.; Van der Pyl, N. [H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol Bs8 ITL (United Kingdom); Molnar, S. M. [LeCosPA Center, National Taiwan University, Taipei 10617, Taiwan (China); Moustakas, L., E-mail: jack@caltech.edu [Jet Propulsion Laboratory, Pasadena, CA 91109 (United States)

2013-05-10T23:59:59.000Z

24

Small-sample brain mapping: sparse recovery on spatially correlated designs with randomization and clustering  

E-Print Network [OSTI]

Small-sample brain mapping: sparse recovery on spatially correlated designs with randomization Abstract Functional neuroimaging can measure the brain's response to an external stimulus. It is used to perform brain mapping: identifying from these observations the brain regions in- volved. This problem can

Paris-Sud XI, Université de

25

RHAPSODY. I. STRUCTURAL PROPERTIES AND FORMATION HISTORY FROM A STATISTICAL SAMPLE OF RE-SIMULATED CLUSTER-SIZE HALOS  

SciTech Connect (OSTI)

We present the first results from the RHAPSODY cluster re-simulation project: a sample of 96 'zoom-in' simulations of dark matter halos of 10{sup 14.8{+-}0.05} h {sup -1} M {sub Sun }, selected from a 1 h {sup -3} Gpc{sup 3} volume. This simulation suite is the first to resolve this many halos with {approx}5 Multiplication-Sign 10{sup 6} particles per halo in the cluster mass regime, allowing us to statistically characterize the distribution of and correlation between halo properties at fixed mass. We focus on the properties of the main halos and how they are affected by formation history, which we track back to z = 12, over five decades in mass. We give particular attention to the impact of the formation history on the density profiles of the halos. We find that the deviations from the Navarro-Frenk-White (NFW) model and the Einasto model depend on formation time. Late-forming halos tend to have considerable deviations from both models, partly due to the presence of massive subhalos, while early-forming halos deviate less but still significantly from the NFW model and are better described by the Einasto model. We find that the halo shapes depend only moderately on formation time. Departure from spherical symmetry impacts the density profiles through the anisotropic distribution of massive subhalos. Further evidence of the impact of subhalos is provided by analyzing the phase-space structure. A detailed analysis of the properties of the subhalo population in RHAPSODY is presented in a companion paper.

Wu, Hao-Yi; Hahn, Oliver; Wechsler, Risa H.; Mao, Yao-Yuan; Behroozi, Peter S., E-mail: hywu@umich.edu [Kavli Institute for Particle Astrophysics and Cosmology, Physics Department, Stanford University, Stanford, CA 94305 (United States)

2013-02-15T23:59:59.000Z

26

THE SPATIAL CLUSTERING OF ROSAT ALL-SKY SURVEY ACTIVE GALACTIC NUCLEI. III. EXPANDED SAMPLE AND COMPARISON WITH OPTICAL ACTIVE GALACTIC NUCLEI  

SciTech Connect (OSTI)

This is the third paper in a series that reports on our investigation of the clustering properties of active galactic nuclei (AGNs) identified in the ROSAT All-Sky Survey (RASS) and the Sloan Digital Sky Survey (SDSS). In this paper, we extend the redshift range to 0.07 < z < 0.50 and measure the clustering amplitudes of both X-ray-selected and optically selected SDSS broad-line AGNs with and without radio detections as well as for X-ray-selected narrow-line RASS/SDSS AGNs. We measure the clustering amplitude through cross-correlation functions (CCFs) with SDSS galaxies and derive the bias by applying a halo occupation distribution model directly to the CCFs. We find no statistically convincing difference in the clustering of X-ray-selected and optically selected broad-line AGNs, as well as with samples in which radio-detected AGNs are excluded. This is in contrast to low-redshift optically selected narrow-line AGNs, where radio-loud AGNs are found in more massive halos than optical AGNs without a radio detection. The typical dark matter halo masses of our broad-line AGNs are log (M{sub DMH}/[h{sup -1} M{sub Sun }]) {approx} 12.4-13.4, consistent with the halo mass range of typical non-AGN galaxies at low redshifts. We find no significant difference between the clustering of X-ray-selected narrow-line AGNs and broad-line AGNs. We confirm the weak dependence of the clustering strength on AGN X-ray luminosity at a {approx}2{sigma} level. Finally, we summarize the current picture of AGN clustering to z {approx} 1.5 based on three-dimensional clustering measurements.

Krumpe, Mirko; Coil, Alison L. [University of California, San Diego, Center for Astrophysics and Space Sciences, 9500 Gilman Drive, La Jolla, CA 92093-0424 (United States); Miyaji, Takamitsu; Aceves, Hector, E-mail: mkrumpe@ucsd.edu [IAUNAM-E (Instituto de Astronomia de la Universidad Nacional Autonoma de Mexico, Ensenada), P.O. Box 439027, San Diego, CA 92143-9027 (United States)

2012-02-10T23:59:59.000Z

27

The SEGUE Stellar Parameter Pipeline. IV. Validation with an Extended Sample of Galactic Globular and Open Clusters  

SciTech Connect (OSTI)

Spectroscopic and photometric data for likely member stars of five Galactic globular clusters (M 3, M 53, M 71, M 92, and NGC 5053) and three open clusters (M 35, NGC 2158, and NGC 6791) are processed by the current version of the SEGUE Stellar Parameter Pipeline (SSPP), in order to determine estimates of metallicities and radial velocities for the clusters. These results are then compared to values from the literature. We find that the mean metallicity (<[Fe/H]>) and mean radial velocity (hRVi) estimates for each cluster are almost all within 2{sigma} of the adopted literature values; most are within 1{sigma}. We also demonstrate that the new version of the SSPP achieves small, but noteworthy, improvements in <[Fe/H]> estimates at the extrema of the cluster metallicity range, as compared to a previous version of the pipeline software. These results provide additional confidence in the application of the SSPP for studies of the abundances and kinematics of stellar populations in the Galaxy.

Smolinski, Jason P.; Beers, Timothy C.; Lee, Young Sun; /Michigan State U. /Michigan State U., JINA; An, Deokkeun; /Ewha Women's U., Seoul; Bickerton, Steven J.; /Princeton U., Astrophys. Sci. Dept.; Johnson, Jennifer A.; /Ohio State U., Dept. Astron.; Loomis, Craig P.; /Princeton U., Astrophys. Sci. Dept.; Rockosi, Constance M.; /Lick Observ.; Sivarani, Thirupathi; /Bangalore, Indian Inst. Astrophys.; Yanny, Brian; /Fermilab

2010-08-01T23:59:59.000Z

28

Radial Alignment of Cluster Galaxies  

E-Print Network [OSTI]

We report the discovery of a statistically significant radial alignment of cluster galaxies in a sample of 85 X-ray selected clusters observed in the Sloan Digital Sky Survey. The tendency for alignment is a robust feature of our sample and does not vary significantly with individual cluster or galaxy properties. We use dynamical arguments to show that a significant fraction of cluster galaxies should be undergoing a parametric tidal resonance that can cause their long axes to orient themselves towards the center of the cluster potential, and therefore tentatively ascribe the observed radial alignment to this dynamical effect.

M. J. Pereira; J. R. Kuhn

2005-05-25T23:59:59.000Z

29

CLUSTER CHEMISTRY  

E-Print Network [OSTI]

atoms [9]. react. , metal carbide clusters had inguished athat we have sought is a carbide metal cluster in which theof metal atoms because reaction at the carbide site must be

Muetterties, Earl L.

2013-01-01T23:59:59.000Z

30

Confirming EIS Clusters. Optical and Infrared Imaging  

E-Print Network [OSTI]

Clusters of galaxies are important targets in observationally cosmology, as they can be used both to study the evolution of the galaxies themselves and to constrain cosmological parameters. Here we report on the first results of a major effort to build up a sample of distant galaxy clusters to form the basis for further studies within those fields. We search for simultaneous overdensities in color and space to obtain supporting evidence for the reality of the clusters. We find a confirmation rate for EIS clusters of 66%, suggesting that a total of about 80 clusters with z>=0.6 are within reach using the EIS cluster candidates.

L. F. Olsen; H. E. Jorgensen; M. Scodeggio; L. da Costa; R. Rengelink; M. Nonino; A. Biviano; M. Ramella; W. Boschin

1999-10-25T23:59:59.000Z

31

Cluster Selection and the Evolution of Brightest Cluster Galaxies  

E-Print Network [OSTI]

The K-band Hubble diagram of Brightest Cluster Galaxies (BCGs) is presented for a large, X-ray selected cluster sample extending out to z = 0.8. The controversy over the degree of BCG evolution is shown to be due to sample selection, since the BCG luminosity depends upon the cluster environment. Selecting only the most X-ray luminous clusters produces a BCG sample which shows, under the assumption of an Einstein-de Sitter cosmology, significantly less mass growth than that predicted by current semi-analytic galaxy formation models, and significant evidence of any growth only if the dominant stellar population of the BCGs formed relatively recently (z <= 2.6).

D. J. Burke; C. A. Collins; R. G. Mann

2000-02-08T23:59:59.000Z

32

CLUSTER CHEMISTRY  

E-Print Network [OSTI]

Advanced Inorganic Chemistry, 11 Wiley Huetterties and C. M.Submitted to the Journal of Organometallic ChemistryCLUSTER CHEMISTRY Earl L. Muetterties TWO-WEEK LOAN COPY May

Muetterties, Earl L.

2013-01-01T23:59:59.000Z

33

Cooling and Clusters: When Is Heating Needed?  

E-Print Network [OSTI]

There are (at least) two unsolved problems concerning the current state of the thermal gas in clusters of galaxies. The first is identifying the source of the heating which offsets cooling in the centers of clusters with short cooling times (the ``cooling flow'' problem). The second is understanding the mechanism which boosts the entropy in cluster and group gas. Since both of these problems involve an unknown source of heating it is tempting to identify them with the same process, particular since AGN heating is observed to be operating at some level in a sample of well-observed ``cooling flow'' clusters. Here we show, using numerical simulations of cluster formation, that much of the gas ending up in clusters cools at high redshift and so the heating is also needed at high-redshift, well before the cluster forms. This indicates that the same process operating to solve the cooling flow problem may not also resolve the cluster entropy problem.

Greg L. Bryan; G. Mark Voit

2005-02-22T23:59:59.000Z

34

The fundamental plane of clusters of galaxies: a quest for understanding cluster dynamics and morphology  

E-Print Network [OSTI]

We discuss implications of the fundamental plane parameters of clusters of galaxies derived from combined optical and X-ray data of a sample of 78 nearby clusters. In particular, we investigate the dependence of these parameters on the dynamical state of the cluster. We introduce a new concept of allocation of the fundamental plane of clusters derived from their intrinsic morphological properties, and put some theoretical implications of the existence of a fundamental plane into perspective.

Christoph Fritsch; Thomas Buchert

1999-03-10T23:59:59.000Z

35

Clustering: Applications  

E-Print Network [OSTI]

Data Compression K Image Processing Center for Geometric Computing Motivation Geometric Clustering = function of frequency of word w i in ff: K What is the distance between two documents ff and fi? ffl d (shell) problem. K Cylinder fitting Center for Geometric Computing Statistical Estimators Geometric

Sharir, Micha

36

A New Method For Robust High-Precision Time-Series Photometry From Well-Sampled Images: Application to Archival MMT/Megacam Observations of the Open Cluster M37  

E-Print Network [OSTI]

We introduce new methods for robust high-precision photometry from well-sampled images of a non-crowded field with a strongly varying point-spread function. For this work, we used archival imaging data of the open cluster M37 taken by MMT 6.5m telescope. We find that the archival light curves from the original image subtraction procedure exhibit many unusual outliers, and more than 20% of data get rejected by the simple filtering algorithm adopted by early analysis. In order to achieve better photometric precisions and also to utilize all available data, the entire imaging database was re-analyzed with our time-series photometry technique (Multi-aperture Indexing Photometry) and a set of sophisticated calibration procedures. The merit of this approach is as follows: we find an optimal aperture for each star with a maximum signal-to-noise ratio, and also treat peculiar situations where photometry returns misleading information with more optimal photometric index. We also adopt photometric de-trending based on ...

Chang, S -W; Hartman, J D

2015-01-01T23:59:59.000Z

37

The APM/Matched-Filter Cluster Catalog  

E-Print Network [OSTI]

A catalog of nearby clusters in the 5800 deg$^2$ area in the southern Galactic cap is constructed by applying a matched-filter cluster-finding algorithm to the sample of 3.3 million galaxies from the APM Galaxy Survey. I have preliminarily detected more than 4000 cluster candidates with estimated redshift of less than 0.2 and with richness similar to those of ACO clusters. Generally, a good correspondence is found between the nearest cluster candidates in our catalog and the ACO clusters which have measured redshift. While the ACO catalog becomes incomplete at z>0.08, the completeness limit of our cluster catalog reaches z=0.15.

Wataru Kawasaki

1999-12-15T23:59:59.000Z

38

The BMW X-ray Cluster Survey  

E-Print Network [OSTI]

We describe the main features of the BMW survey of serendipitous X-ray clusters, based on the still unexploited ROSAT-HRI archival observations. The sky coverage, surface density and first deep optical CCD images of the candidates indicate that this sample can represent an excellent complement to the existing PSPC deep cluster surveys and will provide us with a fully independent probe of the evolution of the cluster abundance, in addition to significantly increasing the number of clusters known at z>0.6.

Alberto Moretti; Luigi Guzzo; Sergio Campana; Stefano Covino; Davide Lazzati; Marcella Longhetti; Emilio Molinari; Maria Rosa Panzera; Gianpiero Tagliaferri; Ian Dell'Antonio

2001-03-21T23:59:59.000Z

39

The BMW X-ray Cluster Survey  

E-Print Network [OSTI]

We describe the main features of the BMW survey of serendipitous X-ray clusters, based on the still unexploited ROSAT-HRI archival observations. The sky coverage, surface density and first deep optical CCD images of the candidates indicate that this sample can represent an excellent complement to the existing PSPC deep cluster surveys and will provide us with a fully independent probe of the evolution of the cluster abundance, in addition to significantly increasing the number of clusters known at z>0.6.

Moretti, A; Campana, S; Covino, S; Lazzati, D; Longhetti, M; Molinari, E; Panzera, M R; Tagliaferri, G; Dell'Antonio, I P; Moretti, Alberto; Guzzo, Luigi; Campana, Sergio; Covino, Stefano; Lazzati, Davide; Longhetti, Marcella; Molinari, Emilio; Panzera, Maria Rosa; Tagliaferri, Gianpiero; Antonio, Ian Dell'

2001-01-01T23:59:59.000Z

40

The 160 Square Degree ROSAT Survey - Revised Catalog & Cluster Evolution  

E-Print Network [OSTI]

We have constructed a large, statistically complete sample of galaxy clusters serendipitously detected as extended X-ray sources in 647 ROSAT PSPC pointed observations. The survey covers 158 square degrees with a median sample flux limit of 1.2 x 10^-13 erg cm^-2 s^-1 (0.5-2.0 keV). Our sample consists of 201 clusters of galaxies characterized by a median redshift of z=0.25 and a maximum of z=1.26. With 22 clusters at z > 0.5, the 160 Square Degree ROSAT Survey is the largest high-redshift sample of X-ray-selected clusters published to date. Here we describe the revised sample which features spectroscopic redshifts for 99.5% of the clusters and discuss the implications for evolution in the cluster abundance.

Mullis, C; Quintana, H; Vikhlinin, A; Henry, P; Gioia, I; Hornstrup, A; Forman, W; Jones, C; Mullis, Christopher; Namara, Brian Mc; Quintana, Hernan; Vikhlinin, Alexey; Henry, Patrick; Gioia, Isabella; Hornstrup, Allan; Forman, William; Jones, Christine

2003-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "four-stage cluster sampling" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Cosmography with cluster strong lensing  

E-Print Network [OSTI]

By stacking an ensemble of strong lensing clusters, we demonstrate the feasibility of placing constraints on the dark energy equation of state. This is achieved by using multiple images of sources at two or more distinct redshift planes. The sample of smooth clusters in our simulations is based on observations of massive clusters and the distribution of background galaxies is constructed using the Hubble Deep Field. Our source distribution reproduces the observed redshift distribution of multiply imaged sources in Abell 1689. The cosmology recovery depends on the number of image families with known spectroscopic redshifts and the number of stacked clusters. Our simulations suggest that constraints comparable to those derived from other competing established techniques on a constant dark energy equation of state can be obtained using 10 to 40 clusters with 5 or more families of multiple images. We have also studied the observational errors in the image redshifts and positions. We find that spectroscopic redshifts and high resolution {\\it Hubble Space Telescope} images are required to eliminate confidence contour relaxation relative to the ideal case in our simulations. This suggests that the dark energy equation of state, and other cosmological parameters, can be constrained with existing {\\it Hubble Space Telescope} images of lensing clusters coupled with dedicated ground-based arc spectroscopy.

James Gilmore; Priyamvada Natarajan

2009-05-29T23:59:59.000Z

42

THE MASSIVE DISTANT CLUSTERS OF WISE SURVEY: THE FIRST DISTANT GALAXY CLUSTER DISCOVERED BY WISE  

SciTech Connect (OSTI)

We present spectroscopic confirmation of a z = 0.99 galaxy cluster discovered using data from the Wide-field Infrared Survey Explorer (WISE). This is the first z {approx} 1 cluster candidate from the Massive Distant Clusters of WISE Survey to be confirmed. It was selected as an overdensity of probable z {approx}> 1 sources using a combination of WISE and Sloan Digital Sky Survey DR8 photometric catalogs. Deeper follow-up imaging data from Subaru and WIYN reveal the cluster to be a rich system of galaxies, and multi-object spectroscopic observations from Keck confirm five cluster members at z = 0.99. The detection and confirmation of this cluster represents a first step toward constructing a uniformly selected sample of distant, high-mass galaxy clusters over the full extragalactic sky using WISE data.

Gettings, Daniel P.; Gonzalez, Anthony H.; Mancone, Conor [Department of Astronomy, University of Florida, 211 Bryant Space Center, Gainesville, FL 32611 (United States); Stanford, S. Adam [Institute of Geophysics and Planetary Physics, Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Eisenhardt, Peter R. M.; Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Brodwin, Mark [Department of Physics and Astronomy, University of Missouri, 5110 Rockhill Road, Kansas City, MO 64110 (United States); Zeimann, Gregory R. [Department of Physics, University of California, One Shields Avenue, Davis, CA 95616 (United States); Masci, Frank J. [Infrared Processing and Analysis Center, California Institute of Technology 100-22, Pasadena, CA 91125 (United States); Papovich, Casey [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, and Department of Physics and Astronomy, Texas A and M University, College Station, TX, 77843-4242 (United States); Tanaka, Ichi [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A'ohoku Place, Hilo, HI 96720 (United States); Wright, Edward L. [UCLA Astronomy, P.O. Box 951547, Los Angeles, CA 90095-1547 (United States)

2012-11-01T23:59:59.000Z

43

Technique for fast and efficient hierarchical clustering  

DOE Patents [OSTI]

A fast and efficient technique for hierarchical clustering of samples in a dataset includes compressing the dataset to reduce a number of variables within each of the samples of the dataset. A nearest neighbor matrix is generated to identify nearest neighbor pairs between the samples based on differences between the variables of the samples. The samples are arranged into a hierarchy that groups the samples based on the nearest neighbor matrix. The hierarchy is rendered to a display to graphically illustrate similarities or differences between the samples.

Stork, Christopher

2013-10-08T23:59:59.000Z

44

Which young clusters/associations are we missing today?  

E-Print Network [OSTI]

Currently clusters/associations of stars are mainly detected as surface density enhancements relative to the background field. While clusters form, their surface density increases. It likely decreases again at the end of the star formation process when the system expands as a consequence of gas expulsion. Therefore the surface density of a single cluster can change considerably in young clusters/associations during the first 20 Myr of their development. We investigate the effect of the gas expulsion on the detectability of clusters/associations typical for the solar neighborhood, where the star formation efficiency is 4 Myr only the most massive clusters are identified, while systems with initially M_c < 3 000 M(sun) are missing. The temporal development of stellar properties is usually determined by observing clusters of different ages. The potentially strong inhomogeneity of the cluster sample makes this methods highly questionable. However, GAIA could provide the means to rectify this situation as it w...

Pfalzner, Susanne; Xiang, Mai

2015-01-01T23:59:59.000Z

45

Clustering of HI galaxies in HIPASS and ALFALFA  

E-Print Network [OSTI]

We investigate the clustering of HI-selected galaxies in the ALFALFA survey and compare results with those obtained for HIPASS. Measurements of the angular correlation function and the inferred 3D-clustering are compared with results from direct spatial-correlation measurements. We are able to measure clustering on smaller angular scales and for galaxies with lower HI masses than was previously possible. We calculate the expected clustering of dark matter using the redshift distributions of HIPASS and ALFALFA and show that the ALFALFA sample is somewhat more anti-biased with respect to dark matter than the HIPASS sample.

Passmoor, S S; Faltenbacher, A

2011-01-01T23:59:59.000Z

46

Statistical fractal analysis of 25 young star clusters  

E-Print Network [OSTI]

A large sample of young stellar groups is analysed aiming to investigate their clustering properties and dynamical evolution. A comparison of the Q statistical parameter, measured for the clusters, with the fractal dimension estimated for the projected clouds shows that 52% of the sample has substructures and tends to follow the theoretically expected relation between clusters and clouds, according to calculations for artificial distribution of points. The fractal statistics was also compared to structural parameters revealing that clusters having radial density profile show a trend of parameter s increasing with mean surface stellar density. The core radius of the sample, as a function of age, follows a distribution similar to that observed in stellar groups of Milky Way and other galaxies. They also have dynamical age, indicated by their crossing time that is similar to unbound associations. The statistical analysis allowed us to separate the sample into two groups showing different clustering characteristi...

Gregorio-Hetem, J; Santos-Silva, T; Fernandes, B

2015-01-01T23:59:59.000Z

47

THE STRUCTURE OF 2MASS GALAXY CLUSTERS  

SciTech Connect (OSTI)

We use a sample of galaxies from the Two Micron All Sky Survey Extended Source Catalog to refine a matched filter method of finding galaxy clusters that takes into account each galaxy's position, magnitude, and redshift if available. The matched filter postulates a radial density profile, luminosity function, and line-of-sight velocity distribution for cluster galaxies. We use this method to search for clusters in the galaxy catalog, which is complete to an extinction-corrected K-band magnitude of 13.25 and has spectroscopic redshifts for roughly 40% of the galaxies, including nearly all brighter than K = 11.25. We then use a stacking analysis to determine the average luminosity function, radial distribution, and velocity distribution of cluster galaxies in several richness classes, and use the results to update the parameters of the matched filter before repeating the cluster search. We also investigate the correlations between a cluster's richness and its velocity dispersion and core radius using these relations to refine priors that are applied during the cluster search process. After the second cluster search iteration, we repeat the stacking analysis. We find a cluster galaxy luminosity function that fits a Schechter form, with parameters M{sub K*} - 5log h = -23.64 {+-} 0.04 and {alpha} = -1.07 {+-} 0.03. We can achieve a slightly better fit to our luminosity function by adding a Gaussian component on the bright end to represent the brightest cluster galaxy population. The radial number density profile of galaxies closely matches a projected Navarro-Frenk-White profile at intermediate radii, with deviations at small radii due to well-known cluster centering issues and outside the virial radius due to correlated structure. The velocity distributions are Gaussian in shape, with velocity dispersions that correlate strongly with richness.

Blackburne, Jeffrey A.; Kochanek, Christopher S. [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States)

2012-01-01T23:59:59.000Z

48

Correspondence Clustering: An Approach to Cluster Multiple Related Spatial Datasets  

E-Print Network [OSTI]

Correspondence Clustering: An Approach to Cluster Multiple Related Spatial Datasets Vadeerat spatial datasets. This capability is important for change analysis and contrast mining. In this paper spatial datasets by maximizing cluster interestingness and correspondence between clusters derived from

Eick, Christoph F.

49

The richness dependence of galaxy cluster correlations: Results from a redshift survey of rich APM clusters  

E-Print Network [OSTI]

We analyse the spatial clustering properties of a new catalogue of very rich galaxy clusters selected from the APM Galaxy Survey. These clusters are of comparable richness and space density to Abell Richness Class $\\geq 1$ clusters, but selected using an objective algorithm from a catalogue demonstrably free of artificial inhomogeneities. Evaluation of the two-point correlation function $\\xi_{cc}(r)$ for the full sample and for richer subsamples reveals that the correlation amplitude is consistent with that measured for lower richness APM clusters and X-ray selected clusters. We apply a maxmimum likelihood estimator to find the best fitting slope and amplitude of a power law fit to $\\xi_{cc}(r)$, and to estimate the correlation length $r_{0}$ (the value of $r$ at which $\\xi_{cc}(r)$ is equal to unity). For clusters with a mean space density of $1.6\\times 10^{-6}\\hmpccc$ (equivalent to the space density of Abell Richness $\\geq 2$ clusters), we find $r_{0}=21.3^{+11.1}_{-9.3} \\hmpc$ (95% confidence limits). This is consistent with the weak richness dependence of $\\xi_{cc}(r)$ expected in Gaussian models of structure formation. In particular, the amplitude of $\\xi_{cc}(r)$ at all richnesses matches that of $\\xi_{cc}(r)$ for clusters selected in N-Body simulations of a low density Cold Dark Matter model.

Rupert A. C. Croft; Gavin B. Dalton; George Efstathiou; Will Sutherland; Steve Maddox

1997-01-09T23:59:59.000Z

50

Intergalactic Globular Clusters  

E-Print Network [OSTI]

We confirm and extend our previous detection of a population of intergalactic globular clusters in Abell 1185, and report the first discovery of an intergalactic globular cluster in the nearby Virgo cluster of galaxies. The numbers, colors and luminosities of these objects can place constraints on their origin, which in turn may yield new insights to the evolution of galaxies in dense environments.

Michael J. West; Patrick Cote; Henry C. Ferguson; Michael D. Gregg; Andres Jordan; Ronald O. Marzke; Nial R. Tanvir; Ted von Hippel

2003-09-23T23:59:59.000Z

51

New Candidate Massive Clusters from 2MASS  

E-Print Network [OSTI]

Massive stars are important for the evolution of the interstellar medium. The detailed study of their properties (such as mass loss, rotation, magnetic fields) is enormously facilitated by samples of these objects in young massive galactic star clusters. Using 2MASS we have searched for so far unknown candidates of red supergiant clusters along the Galactic Plane. Utilising deep high resolution UKIDSS GPS and VISTA VVV data to study colour-magnitude diagrams, we uncover six new massive cluster candidates in the inner Galaxy. If spectroscopically confirmed as real clusters, two of them could be part of the Scutum-Complex. One cluster candidate has a number of potential red supergiant members comparable to RSGC1 and 3. Our investigation of UKIDSS data reveals for the first time the main sequence of the massive cluster RSGC2. The stars of the sequence show an increased projected density at the same position as the known red supergiants in the cluster and have E(J-K)=1.6mag. This either indicates an unusual extin...

Froebrich, D

2013-01-01T23:59:59.000Z

52

The Apm Galaxy Survey IV: Redshifts of Rich Clusters of Galaxies  

E-Print Network [OSTI]

We present redshifts for a sample of 229 clusters selected from the APM Galaxy Survey, 189 of which are new redshift determinations. Non-cluster galaxy redshifts have been rejected from this sample using a likelihood ratio test based on the projected and apparent magnitude distributions of the cluster fields. We test this technique using cluster fields in which redshifts have been measured for more than 10 galaxies. Our redshift sample is nearly complete and has been used in previous papers to study the three dimensional distribution of rich clusters of galaxies. 157 of the clusters in our sample are listed in the Abell catalogue or supplement, and the remainder are new cluster identifications.

G. B. Dalton; G. Efstathiou; S. J. Maddox; W. J. Sutherland

1993-11-16T23:59:59.000Z

53

The Alignment effect of brightest cluster galaxies in the SDSS  

SciTech Connect (OSTI)

One of the most vital observational clues for unraveling the origin of Brightest Cluster Galaxies (BCG) is the observed alignment of the BCGs with their host cluster and its surroundings. We have examined the BCG-cluster alignment effect, using clusters of galaxies detected from the Sloan Digital Sky Survey (SDSS). We find that the BCGs are preferentially aligned with the principal axis of their hosts, to a much higher redshift (z >~ 0.3) than probed by previous studies (z <~ 0.1). The alignment effect strongly depends on the magnitude difference of the BCG and the second and third brightest cluster members: we find a strong alignment effect for the dominant BCGs, while less dominant BCGs do not show any departure from random alignment with respect to the cluster. We therefore claim that the alignment process originates from the same process that makes the BCG grow dominant, be it direct mergers in the early stage of cluster formation, or a later process that resembles the galactic cannibalism scenario. We do not find strong evidence for (or against) redshift evolution between 0sample size (< 200 clusters). However, we have developed a framework by which we can examine many more clusters in an automated fashion for the upcoming SDSS cluster catalogs, which will provide us with better statistics for systematic investigations of the alignment with redshift, richness and morphology of both the cluster and the BCG.

Kim, R. S. J. [Princeton Univ., Princeton, NJ (United States); Annis, J. [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Strauss, M. A. [Princeton Univ., Princeton, NJ (United States); Lupton, R. H. [Princeton Univ., Princeton, NJ (United States); Bahcall, N. A. [Princeton Univ., Princeton, NJ (United States); Gunn, J. E. [Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States); Kepner, J. V. [MIT Lincoln Laboratory, Lexington, MA (United States); Postman, M. [Space Telescope Science Institute, Baltimore, MD (United States)

2001-10-01T23:59:59.000Z

54

ISO's Contribution to the Study of Clusters of Galaxies  

E-Print Network [OSTI]

Starting with nearby galaxy clusters like Virgo and Coma, and continuing out to the furthest galaxy clusters for which ISO results have yet been published ($z=0.56$), we discuss the development of knowledge of the infrared and associated physical properties of galaxy clusters from early IRAS observations, through the "ISO-era" to the present, in order to explore the status of ISO's contribution to this field. Relevant IRAS and ISO programmes are reviewed, addressing both the cluster galaxies and the still-very-limited evidence for an infrared-emitting intra-cluster medium. ISO made important advances in knowledge of both nearby and distant galaxy clusters, such as the discovery of a major cold dust component in Virgo and Coma cluster galaxies, the elaboration of the correlation between dust emission and Hubble-type, and the detection of numerous Luminous Infrared Galaxies (LIRGs) in several distant clusters. These and consequent achievements are underlined and described. We recall that, due to observing time constraints, ISO's coverage of higher-redshift galaxy clusters to the depths required to detect and study statistically significant samples of cluster galaxies over a range of morphological types could not be comprehensive and systematic, and such systematic coverage of distant clusters will be an important achievement of the Spitzer Observatory.

L. Metcalfe; D. Fadda; A. Biviano

2005-08-22T23:59:59.000Z

55

Accelerated Fuzzy Clustering.  

E-Print Network [OSTI]

??Clustering algorithms are a primary tool in data analysis, facilitating the discovery of groups and structure in unlabeled data. They are used in a wide… (more)

Parker, Jonathon Karl

2013-01-01T23:59:59.000Z

56

Heating Rate Profiles in Galaxy Clusters  

E-Print Network [OSTI]

In recent years evidence has accumulated suggesting that the gas in galaxy clusters is heated by non-gravitational processes. Here we calculate the heating rates required to maintain a physically motived mass flow rate, in a sample of seven galaxy clusters. We employ the spectroscopic mass deposition rates as an observational input along with temperature and density data for each cluster. On energetic grounds we find that thermal conduction could provide the necessary heating for A2199, Perseus, A1795 and A478. However, the suppression factor, of the clasical Spitzer value, is a different function of radius for each cluster. Based on the observations of plasma bubbles we also calculate the duty cycles for each AGN, in the absence of thermal conduction, which can provide the required energy input. With the exception of Hydra-A it appears that each of the other AGNs in our sample require duty cycles of roughly $10^{6}-10^{7}$ yrs to provide their steady-state heating requirements. If these duty cycles are unrealistic, this may imply that many galaxy clusters must be heated by very powerful Hydra-A type events interspersed between more frequent smaller-scale outbursts. The suppression factors for the thermal conductivity required for combined heating by AGN and thermal conduction are generally acceptable. However, these suppression factors still require `fine-tuning` of the thermal conductivity as a function of radius. As a consequence of this work we present the AGN duty cycle as a cooling flow diagnostic.

Edward C. D. Pope; Georgi Pavlovski; Christian R. Kaiser; Hans Fangohr

2006-01-05T23:59:59.000Z

57

Clustering versus non-clustering phase synchronizations  

SciTech Connect (OSTI)

Clustering phase synchronization (CPS) is a common scenario to the global phase synchronization of coupled dynamical systems. In this work, a novel scenario, the non-clustering phase synchronization (NPS), is reported. It is found that coupled systems do not transit to the global synchronization until a certain sufficiently large coupling is attained, and there is no clustering prior to the global synchronization. To reveal the relationship between CPS and NPS, we further analyze the noise effect on coupled phase oscillators and find that the coupled oscillator system can change from CPS to NPS with the increase of noise intensity or system disorder. These findings are expected to shed light on the mechanism of various intriguing self-organized behaviors in coupled systems.

Liu, Shuai [Wuhan Center for Magnetic Resonance, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China) [Wuhan Center for Magnetic Resonance, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhan, Meng, E-mail: zhanmeng@wipm.ac.cn [Wuhan Center for Magnetic Resonance, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China)] [Wuhan Center for Magnetic Resonance, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China)

2014-03-15T23:59:59.000Z

58

Blue Stragglers in Low-Luminosity Star Clusters  

E-Print Network [OSTI]

We examine the blue straggler populations of 13 low-luminosity (M_V_t >~ -6) globular clusters and 2 old open clusters. These clusters test blue straggler formation in environments intermediate between higher luminosity (and usually higher density) clusters and the Galactic field. The anti-correlation between the relative frequency of blue stragglers (F_BSS = N_BSS / N_HB) and cluster luminosity continues to the lowest luminosity clusters, which have frequencies meeting or exceeding that of field stars. In addition we find that the anti-correlation between straggler frequency and central density disappears for clusters with density less than about 300 L_V,sun pc^-3, although this appears to be an artifact of the correlation between cluster luminosity and central density. We argue on observational (wide, eccentric binaries containing blue stragglers in M67, and the existence of very bright stragglers in most of the clusters in our sample) and theoretical grounds that stellar collisions still produce a significant fraction of the blue stragglers in low luminosity star clusters due to the long-term survival of wide binaries.

Eric L. Sandquist

2005-10-26T23:59:59.000Z

59

Energy Landscapes of Planar Colloidal Clusters  

E-Print Network [OSTI]

Energy Landscapes of Planar Colloidal Clusters John W. R. Morgan,a and David J. Wales?b Received Xth XXXXXXXXXX 20XX, Accepted Xth XXXXXXXXX 20XX First published on the web Xth XXXXXXXXXX 20XX DOI: 10.1039/b000000x A short-ranged pairwise Morse... potential is used to model colloidal clusters with planar morphologies. Potential and free energy global minima as well as rearrangement paths, obtained by basin-hopping global optimisation and discrete path sampling, are characterised. The potential...

Morgan, John W. R.; Wales, David J.

2014-07-24T23:59:59.000Z

60

SciCloneSciClone A Cluster of Clusters forA Cluster of Clusters for  

E-Print Network [OSTI]

Enable cross-disciplinary graduate programs ·· Provide research facility for scientific computingProvide research facility for scientific computing ­­ ""SciCloneSciClone ClusterCluster"" (Science (LAM, ATLAS, NAMD, etc.)Tool development (LAM, ATLAS, NAMD, etc.) ·· Instruction (classes, graduate

Lewis, Robert Michael

Note: This page contains sample records for the topic "four-stage cluster sampling" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

Cool Cluster Correctly Correlated  

SciTech Connect (OSTI)

Atomic clusters are unique objects, which occupy an intermediate position between atoms and condensed matter systems. For a long time it was thought that physical and chemical properties of atomic dusters monotonically change with increasing size of the cluster from a single atom to a condensed matter system. However, recently it has become clear that many properties of atomic clusters can change drastically with the size of the clusters. Because physical and chemical properties of clusters can be adjusted simply by changing the cluster's size, different applications of atomic clusters were proposed. One example is the catalytic activity of clusters of specific sizes in different chemical reactions. Another example is a potential application of atomic clusters in microelectronics, where their band gaps can be adjusted by simply changing cluster sizes. In recent years significant advances in experimental techniques allow one to synthesize and study atomic clusters of specified sizes. However, the interpretation of the results is often difficult. The theoretical methods are frequently used to help in interpretation of complex experimental data. Most of the theoretical approaches have been based on empirical or semiempirical methods. These methods allow one to study large and small dusters using the same approximations. However, since empirical and semiempirical methods rely on simple models with many parameters, it is often difficult to estimate the quantitative and even qualitative accuracy of the results. On the other hand, because of significant advances in quantum chemical methods and computer capabilities, it is now possible to do high quality ab-initio calculations not only on systems of few atoms but on clusters of practical interest as well. In addition to accurate results for specific clusters, such methods can be used for benchmarking of different empirical and semiempirical approaches. The atomic clusters studied in this work contain from a few atoms to tens of atoms. Therefore, they are quantum objects. Some qualitative information about the geometries of such clusters can be obtained with classical empirical methods, for example geometry optimization using an empirical Lennard-Jones potential. However, to predict their accurate geometries and other physical and chemical properties it is necessary to solve a Schroedinger equation. If one is not interested in dynamics of clusters it is enough to solve the stationary (time-independent) Schroedinger equation (H{Phi}=E{Phi}). This equation represents a multidimensional eigenvalue problem. The solution of the Schroedinger equation is a set of eigenvectors (wave functions) and their eigenvalues (energies). The lowest energy solution (wave function) corresponds to the ground state of the cluster. The other solutions correspond to excited states. The wave function gives all information about the quantum state of the cluster and can be used to calculate different physical and chemical properties, such as photoelectron, X-ray, NMR, EPR spectra, dipole moment, polarizability etc. The dimensionality of the Schroedinger equation is determined by the number of particles (nuclei and electrons) in the cluster. The analytic solution is only known for a two particle problem. In order to solve the equation for clusters of interest it is necessary to make a number of approximations and use numerical methods.

Sergey Aleksandrovich Varganov

2005-12-17T23:59:59.000Z

62

The Baltimore and Utrecht models for cluster dissolution  

E-Print Network [OSTI]

The analysis of the age distributions of star cluster samples of different galaxies has resulted in two very different empirical models for the dissolution of star clusters: the Baltimore model and the Utrecht model. I describe these two models and their differences. The Baltimore model implies that the dissolution of star clusters is mass independent and that about 90% of the clusters are destroyed each age dex, up to an age of about a Gyr, after which point mass-dependent dissolution from two-body relaxation becomes the dominant mechanism. In the Utrecht model, cluster dissolution occurs in three stages: (i) mass-independent infant mortality due to the expulsion of gas up to about 10 Myr; (ii) a phase of slow dynamical evolution with strong evolutionary fading of the clusters lasting up to about a Gyr; and (iii) a phase dominated by mass dependent-dissolution, as predicted by dynamical models. I describe the cluster age distributions for mass-limited and magnitude-limited cluster samples for both models. I refrain from judging the correctness of these models.

Henny J. G. L. M. Lamers

2008-04-14T23:59:59.000Z

63

Best Clustering Configuration Metrics: Towards Multiagent Based Clustering  

E-Print Network [OSTI]

with algorithms to conduct clustering operations or to validate the output from clus- tering algorithms, some

Atkinson, Katie

64

Clustering in nuclear environment  

E-Print Network [OSTI]

The properties of few-body clusters (mass number $A \\le 4$) are modified if they are immersed in a nuclear medium. In particular, Pauli blocking that reflects the antisymmetrization of the many-body wave function is responsible for the medium modification of light clusters and the dissolution with increasing density. A more consistent description is given with takes also the contribution of correlations in the continuum into account. The relation between cluster formation in warm dense matter and in nuclear structure is discussed.

G. Röpke

2014-08-12T23:59:59.000Z

65

Small Community Wastewater Cluster Systems  

E-Print Network [OSTI]

Small Community Wastewater Cluster Systems Don Jones, Jacqui Bauer, Richard Wise, and Alan Dunn* ID-265 #12;Small Community Wastewater Cluster Systems ID-265 2 It is the policy of the Purdue University Community Wastewater Cluster Systems ID-265 3 Small Community Wastewater Cluster Systems Table of Contents

Holland, Jeffrey

66

CMB-Cluster Lensing  

E-Print Network [OSTI]

Clusters of galaxies are powerful cosmological probes, particularly if their masses can be determined. One possibility for mass determination is to study the cosmic microwave background (CMB) on small angular scales and observe deviations from a pure gradient due to lensing of massive clusters. I show that, neglecting contamination, this technique has the power to determine cluster masses very accurately, in agreement with estimates by Seljak and Zaldarriaga (1999). However, the intrinsic small scale structure of the CMB significantly degrades this power. The resulting mass constraints are useless unless one imposes a prior on the concentration parameter c. With even a modest prior on c, an ambitious CMB experiment (0.5' resolution and 1 microK per pixel) could determine masses of high redshift (z>0.5) clusters with ~ 30% accuracy.

Scott Dodelson

2004-02-12T23:59:59.000Z

67

The 2dF Galaxy Redshift Survey: The clustering of galaxy groups  

E-Print Network [OSTI]

We measure the clustering of galaxy groups in the 2dFGRS Percolation-Inferred Galaxy Group (2PIGG) catalogue. The 2PIGG sample has 29,000 groups with at least two members. The clustering amplitude of the full 2PIGG catalogue is weaker than that of 2dFGRS galaxies, in agreement with theoretical predictions. We have subdivided the 2PIGG catalogue into samples that span a factor of 25 in median total luminosity. Our correlation function measurements span an unprecedented range of clustering strengths, connecting the regimes probed by groups fainter than L* galaxies and rich clusters. There is a steady increase in clustering strength with group luminosity; the most luminous groups are ten times more strongly clustered than the full 2PIGG catalogue. We demonstrate that the 2PIGG results are in very good agreement with the clustering of groups expected in the LCDM model.

Nelson D. Padilla; C. M. Baugh; V. R. Eke; P. Norberg; S. Cole; C. S. Frenk; D. J. Croton; I. K. Baldry; J. Bland-Hawthorn; T. Bridges; R. Cannon; M. Colless; C. Collins; W. Couch; G. Dalton; R. De Propris; S. P. Driver; G. Efstathiou; R. S. Ellis; K. Glazebrook; C. Jackson; O. Lahav; I. Lewis; S. Lumsden; S. Maddox; D. Madgwick; J. A. Peacock; B. A. Peterson; W. Sutherland; K. Taylor.

2004-07-12T23:59:59.000Z

68

Star Cluster Ecology: VII The evolution of young dense star clusters containing primordial binaries  

E-Print Network [OSTI]

We study the first 100Myr of the evolution of isolated star clusters initially containing 144179 stars, including 13107 (10%) primordial hard binaries. Our calculations include the effects of both stellar and binary evolution. Gravitational interactions among the stars are computed by direct N-body integration using high precision GRAPE-6 hardware. The evolution of the core radii and central concentrations of our simulated clusters are compared with the observed sample of young (about 100Myr) star clusters in the large Magellanic cloud. Even though our simulations start with a rich population of primordial binaries, core collapse during the early phase of the cluster evolution is not prevented. Throughout the simulations, the fraction of binaries remains roughly constant (about 10%). Due to the effects of mass segregation the mass function of intermediate-mass main-sequence stars becomes as flat as $\\alpha=-1.8$ in the central part of the cluster (where the initial Salpeter mass function had $\\alpha=-2.35$). About 6--12% of the neutron stars were retained in our simulations; the fraction of retained black holes is 40--70%. In each simulation about three neutron stars become members of close binaries with a main-sequence companion. Such a binary will eventually become an x-ray binary, when the main-sequence star starts to fill its Roche lobe. Black holes are found more frequently in binaries; in each simulated cluster we find about 11 potential x-ray binaries containing a black hole. Abstract abbreviated....

Simon Portegies Zwart; Steve McMillan; Jun Makino

2006-09-27T23:59:59.000Z

69

E-Print Network 3.0 - advanced cervix cancer Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

cancer Search Powered by Explorit Topic List Advanced Search Sample search results for: advanced cervix cancer Page: << < 1 2 3 4 5 > >> 1 Tissue Classification using Cluster...

70

E-Print Network 3.0 - advanced cancer cervix Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Powered by Explorit Topic List Advanced Search Sample search results for: advanced cancer cervix Page: << < 1 2 3 4 5 > >> 1 Tissue Classification using Cluster Features for...

71

SED, Metallicity and Age of Halo Globular Clusters in M33  

E-Print Network [OSTI]

In this paper we study the properties of ten halo globular clusters in the nearby spiral galaxy M33. CCD images of M33 were obtained as a part of the BATC Colour Survey of the sky in 13 intermediate-band filters from 3800 to 10000{\\AA}. By aperture photometry, we obtain the spectral energy distributions (SEDs) of these globular clusters. We estimate the ages of our sample clusters by comparing the photometry of each object with theoretical stellar population synthesis models for different values of metallicity. Our results suggest that eight of the ten sample halo globular clusters have ``intermediate'' ages, i.e. between 1 and 8 Gyrs.

Ma, J; Chen, J; Wu, H; Jiang, Z; Xue, S; Zhu, J; Ma, Jun; Zhou, Xu; Chen, Jiansheng; Wu, Hong; Jiang, Zhaoji; Xue, Suijian; Zhu, Jin

2002-01-01T23:59:59.000Z

72

The structure of nickel clusters  

SciTech Connect (OSTI)

The reactions of nickel clusters with ammonia and with water are used to probe cluster geometrical structure. Ammonia uptake experiments allow the determination of the number of preferred binding sites on cluster surfaces. This number shows pronounced minima in the 50- to 116- atom size range for many of the cluster sizes that appear as magic numbers in mass spectra of rare gas clusters. Since these magic numbers arise from closings of shells and subshells of the Mackay icosahedra, the correlation suggests that ammoniated nickel clusters in this size region also have icosahedral structure. Similar structure is found for ammoniated clusters smaller than {similar to}30 atoms, but is not seen for room temperature clusters in the vicinity of the third shell closing at 147 atoms. Icosahedral features do appear for the larger clusters at elevated temperatures. For many clusters above 50 atoms, prolonged exposure to ammonia causes a conversion from the icosahedral structure to some other structure that binds more ammonia molecules, and often the two structures are seen together. The equilibrium reaction of a single water molecule with the bare clusters probes the strength of the cluster--water bond. Enhanced water adsorption is often seen for clusters one atom larger than those showing minima in ammonia uptake, suggesting that these bare clusters likewise have icosahedral structure. The reasons for minima in ammonia uptake and maxima in water binding are discussed.

Parks, E.K.; Winter, B.J.; Klots, T.D.; Riley, S.J. (Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439 (US))

1991-02-01T23:59:59.000Z

73

Control rod cluster arrangement  

SciTech Connect (OSTI)

This patent describes a nuclear reactor including nuclear core which is cooled and moderated by light water, the nuclear core comprising a plurality of parallel arranged openings therethrough and interspersed among the fuel assemblies. A control rod cluster arrangement comprises load follow control rod cluster assemblies with each load follow control rod cluster assembly being adapted to slidingly fit within each of some of the fuel assemblies in the parallel arranged openings, the load follow control rod cluster assemblies each comprising a plurality of elongated parallel arranged rods attached to a single spider, and including a first group of rods and a second group of rods, the first group of rods and the second each consisting of a plurality of absorber rods. The first group of rods consist of absorber rods taken from the group consisting of B/sub 4/C, hafnium, or silver-indium-cadmium and the second group of rods consist of absorber rods each consisting of stainless steel, the first group of rods and the second group of rods each being integrally attached at all times to the single spider, the absorber rods of the second group of rods being dispersed throughout the control rod cluster assembly. The first group of rods have a first neutron capture cross section and the second group of rods have a second neutron capture cross section different from the first cross section.

Orr, W.L.; Doshi, P.K.; Mildrum, C.M.; Freeman, T.R.

1987-02-10T23:59:59.000Z

74

Sampling box  

DOE Patents [OSTI]

An air sampling box that uses a slidable filter tray and a removable filter cartridge to allow for the easy replacement of a filter which catches radioactive particles is disclosed.

Phillips, Terrance D. (617 Chestnut Ct., Aiken, SC 29803); Johnson, Craig (100 Midland Rd., Oak Ridge, TN 37831-0895)

2000-01-01T23:59:59.000Z

75

Photon Clusters in Thermal Radiation  

E-Print Network [OSTI]

Within the framework of Bose-Einstein statistics, it is shown that the blackbody radiation, in addition to single photons, contains photon clusters, or coalescent photons. The probability to find a k-photon cluster versus radiation frequency and temperature is found, as well as the statistics of clusters. Spectra of photon-cluster radiation are calculated as functions of blackbody temperature. The Planck's radiation law is derived based on the existence of photon clusters. The possibility of experimental observation of photon clusters in thermal radiation is discussed.

Aleksey Ilyin

2014-10-30T23:59:59.000Z

76

Thermodynamics of clusterized matter  

E-Print Network [OSTI]

Thermodynamics of clusterized matter is studied in the framework of statistical models with non-interacting cluster degrees of freedom. At variance with the analytical Fisher model, exact Metropolis simulation results indicate that the transition from homogeneous to clusterized matter lies along the $\\rho=\\rho_0$ axis at all temperatures and the limiting point of the phase diagram is not a critical point even if the surface energy vanishes at this point. Sensitivity of the inferred phase diagram to the employed statistical framework in the case of finite systems is discussed by considering the grand-canonical and constant-pressure canonical ensembles. A Wigner-Seitz formalism in which the fragment charge is neutralized by an uniform electron distribution allows to build the phase diagram of neutron star matter.

Ad. R. Raduta; F. Gulminelli

2009-08-26T23:59:59.000Z

77

Optical and X-ray clusters as tracers of the supercluster-void network. III Distribution of Abell and APM clusters  

E-Print Network [OSTI]

We present a comparison of Abell and APM clusters of galaxies as tracers of the large scale structure of the Universe. We investigate selection functions of both cluster catalogs. We show that the supercluster-void network can be traced with both cluster samples; the network has a well-defined period of ~120 h^{-1} Mpc. We calculate the correlation function and the power spectrum for Abell and APM cluster samples. The APM cluster sample with measured redshifts covers a small volume which contains only a few very rich superclusters that surround one void and have exceptionally large mutual separations. Due to this property the maximum of the power spectrum of APM clusters with measured velocities is shifted to larger scales than the corresponding feature in the power spectrum of Abell clusters. We conclude that the APM sample is not representative for the large-scale structure as a whole due to the small space coverage. We present a catalog of superclusters of galaxies, based on APM clusters up to a redshift z_{lim}=0.13.

M. Einasto; J. Einasto; E. Tago; H. Andernach; G. B. Dalton; V. M"uller

2000-12-29T23:59:59.000Z

78

Are the Effects of Structure Formation Seen in the Central Metallicity of Galaxy Clusters?  

E-Print Network [OSTI]

A sample of 46 nearby clusters observed with Chandra is analyzed to produce radial density, temperature, entropy and metallicity profiles, as well as other morphological measurements. The entropy profiles are computed to larger radial extents than in previous Chandra cluster sample analyses. We find that the iron mass fraction measured in the inner 0.15 R500 shows a larger dispersion across the sample of low-mass clusters, than it does for the sample of high-mass clusters. We interpret this finding as the result of the mixing of more haloes in large clusters than in small clusters, which leads to an averaging of the metal content in the large clusters, and thus less dispersion of metallicity for high-mass clusters. This interpretation lends support to the idea that the low-entropy, metal-rich gas of merging haloes reaches clusters' centers, which explains observations of Core-Collapse Supernova products metallicity peaks, and which is seen in hydrodynamical simulations. The gas in these merging haloes would h...

Elkholy, Tamer Y; Canizares, Claude R

2015-01-01T23:59:59.000Z

79

The Infrared Luminosity of Galaxy Clusters  

E-Print Network [OSTI]

The aim of this study is to quantify the infrared luminosity of clusters as a function of redshift and compare this with the X-ray luminosity. This can potentially constrain the origin of the infrared emission to be intracluster dust and/or dust heated by star formation in the cluster galaxies. We perform a statistical analysis of a large sample of galaxy clusters selected from existing databases and catalogues.We coadd the infrared IRAS and X-ray RASS images in the direction of the selected clusters within successive redshift intervals up to z = 1. We find that the total infrared luminosity is very high and on average 20 times higher than the X-ray luminosity. If all the infrared luminosity is to be attributed to emission from diffuse intracluster dust, then the IR to X-ray ratio implies a dust-to-gas mass abundance of 5e-4. However, the infrared luminosity shows a strong enhancement for 0.1 infrared luminosity that we measure is generated by the ongoing star formation in the member galaxies. From theoretical predictions calibrated on extinction measurements (dust mass abundance equal to 1e-5), we expect only a minor contribution, of a few percent, from intracluster dust.

Martin Giard; Ludovic Montier; Etienne Pointecouteau; Ellen Simmat

2008-08-28T23:59:59.000Z

80

Galactic Open Clusters  

E-Print Network [OSTI]

The study of open clusters has a classic feel to it since the subject predates anyone alive today. Despite the age of this topic, I show via an ADS search that its relevance and importance in astronomy has grown faster in the last few decades than astronomy in general. This is surely due to both technical reasons and the interconnection of the field of stellar evolution to many branches of astronomy. In this review, I outline what we know today about open clusters and what they have taught us about a range of topics from stellar evolution to Galactic structure to stellar disk dissipation timescales. I argue that the most important astrophysics we have learned from open clusters is stellar evolution and that its most important product has been reasonably precise stellar ages. I discuss where open cluster research is likely to go in the next few years, as well as in the era of 20m telescopes, SIM, and GAIA. Age will continue to be of wide relevance in astronomy, from cosmology to planet formation timescales, and with distance errors soon no longer a problem, improved ages will be critically important to many of the most fascinating astrophysical questions.

Ted von Hippel

2005-09-06T23:59:59.000Z

Note: This page contains sample records for the topic "four-stage cluster sampling" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Spectral Energy Distributions and Age Estimates of 78 Star Clusters in M33  

E-Print Network [OSTI]

In this third paper of our series, we present CCD spectrophotometry of 78 star clusters that were detected by Chandar, Bianchi, & Ford in the nearby spiral galaxy M33. CCD images of M33 were obtained as a part of the BATC Color Survey of the sky in 13 intermediate-band filters from 3800 to 10000{\\AA}. By aperture photometry, we obtain the spectral energy distributions of these 78 star clusters. As Chandar, Bianchi, & Ford did, we estimate the ages of our sample clusters by comparing the photometry of each object with theoretical stellar population synthesis models for different values of metallicity. We find that the sample clusters formed continuously in M33 from $\\sim 3\\times10^6$ -- $10^{10}$ years. This conclusion is consistent with Chandar, Bianchi, & Ford. The results also show that, there are two peaks in cluster formation, at $\\sim 8\\times10^6$ and $\\sim 10^9$ years in these clusters.

Ma, J; Chen, J; Wu, H; Jiang, Z; Xue, S; Zhu, J; Ma, Jun; Zhou, Xu; Chen, Jiansheng; Wu, Hong; Jiang, Zhaoji; Xue, Suijian; Zhu, Jin

2002-01-01T23:59:59.000Z

82

Connecting Remote Clusters with ATM  

SciTech Connect (OSTI)

Sandia's entry into utilizing clusters of networked workstations is called Computational Plant or CPlant for short. The design of CPlant uses Ethernet to boot the individual nodes, Myrinet to communicate within a node cluster, and ATM to connect between remote clusters. This SAND document covers the work done to enable the use of ATM on the CPlant nodes in the Fall of 1997.

Hu, T.C.; Wyckoff, P.S.

1998-10-01T23:59:59.000Z

83

The Globular Cluster Luminosity Function  

E-Print Network [OSTI]

The main aspects of the globular cluster luminosity function needing to be explained by a general theory of cluster formation are reviewed, and the importance of simultaneously understanding globular cluster systematics (the fundamental plane) within such a theory is pointed out.

Dean E. McLaughlin

2003-02-14T23:59:59.000Z

84

Derivatized gold clusters and antibody-gold cluster conjugates  

DOE Patents [OSTI]

Antibody- or antibody fragment-gold cluster conjugates are shown wherein the conjugate size can be as small as 5.0 nm. Methods and reagents are disclosed in which antibodies, Fab' or F(ab').sub.2 fragments thereof are covalently bound to a stable cluster of gold atoms. The gold clusters may contain 6, 8, 9, 11, 13, 55 or 67 gold atoms in their inner core. The clusters may also contain radioactive gold. The antibody-cluster conjugates are useful in electron microscopy applications as well as in clinical applications that include imaging, diagnosis and therapy.

Hainfeld, James F. (Shoreham, NY); Furuya, Frederic R. (Williston Park, NY)

1994-11-01T23:59:59.000Z

85

Using the central VAX cluster at ANL  

SciTech Connect (OSTI)

This report is a manual that discusses the following topics on the Central Vax Cluster at ANL: What the Central Vax Cluster is; how the Vax Cluster works; operational policies; getting started; using tapes; printing on the Vax Cluster; developing programs in VMS; using the X window system on the Central Vax Cluster; and using Central Vax Cluster file sharing services.

Caruthers, C.M.; Vote, S.L. [eds.; Lifka, D.A.; Raffenetti, R.C.

1992-08-01T23:59:59.000Z

86

On the Nature of the EIS Candidate Clusters: Confirmation of z<0.6 candidates  

E-Print Network [OSTI]

We use public V-band imaging data from the wide-angle surveys conducted by the ESO Imaging Survey project (EIS) to further investigate the nature of the EIS galaxy cluster candidates. These were originally identified by applying a matched-filter algorithm which used positional and photometric data of the galaxy sample extracted from the I-band survey images. In this paper, we apply the same technique to the galaxy sample extracted from V-band data and compare the new cluster detections with the original ones. We find that ~75% of the low-redshift cluster candidates (zEIS clusters with z_I<0.6 are real, making it one of the largest samples of galaxy clusters in this redshift range currently available in the southern hemisphere.

L. F. Olsen; C. Benoist; L. da Costa; M. Scodeggio; H. E. Jorgensen; S. Arnouts; S. Bardelli; A. Biviano; M. Ramella; E. Zucca

2001-10-21T23:59:59.000Z

87

The Era of Star Formation in Galaxy Clusters  

E-Print Network [OSTI]

We analyze the star formation properties of 16 infrared-selected, spectroscopically confirmed galaxy clusters at $1 1.35$. Using infrared luminosities measured with deep Spitzer/MIPS observations at 24 $\\mu$m, along with robust optical+IRAC photometric redshifts and SED-fitted stellar masses, we present the dust-obscured star-forming fractions, star formation rates and specific star formation rates in these clusters as functions of redshift and projected clustercentric radius. We find that $z\\sim 1.4$ represents a transition redshift for the ISCS sample, with clear evidence of an unquenched era of cluster star formation at earlier times. Beyond this redshift the fraction of star-forming cluster members increases monotonically toward the cluster centers. Indeed, the specific star formation rate in the cores of these distant clusters is consistent with field values at similar redshifts, indicating that at $z>1.4$ environment-dependent quenching had not yet been established in ISCS clusters. Combining these obse...

Brodwin, M; Gonzalez, Anthony H; Zeimann, G R; Snyder, G F; Mancone, C L; Pope, A; Eisenhardt, P R; Stern, D; Alberts, S; Ashby, M L N; Brown, M J I; Chary, R -R; Dey, Arjun; Galametz, A; Gettings, D P; Jannuzi, B T; Miller, E D; Moustakas, J; Moustakas, L A

2013-01-01T23:59:59.000Z

88

Binding Energy and the Fundamental Plane of Globular Clusters  

E-Print Network [OSTI]

A physical description of the fundamental plane of Galactic globular clusters is developed which explains all empirical trends and correlations in a large number of cluster observables and provides a small but complete set of truly independent constraints on theories of cluster formation and evolution in the Milky Way. Within the theoretical framework of single-mass, isotropic King models, it is shown that (1) 39 regular (non--core-collapsed) globulars with measured core velocity dispersions share a common V-band mass-to-light ratio of 1.45 +/- 0.10, and (2) a complete sample of 109 regular globulars reveals a very strong correlation between cluster binding energy and total luminosity, regulated by Galactocentric position: E_b \\propto (L^{2.05} r_{\\rm gc}^{-0.4}). The observational scatter about either of these two constraints can be attributed fully to random measurement errors, making them the defining equations of a fundamental plane for globular clusters. A third, weaker correlation, between total luminosity and the King-model concentration parameter, c, is then related to the (non-random) distribution of globulars on the plane. The equations of the FP are used to derive expressions for any cluster observable in terms of only L, r_{\\rm gc}, and c. Results are obtained for generic King models and applied specifically to the globular cluster system of the Milky Way.

Dean E. McLaughlin

2000-02-03T23:59:59.000Z

89

The Distribution of Barred Galaxies in the Virgo Cluster  

E-Print Network [OSTI]

A study of the distribution of barred and nonbarred disk galaxies in the Virgo cluster is presented in an attempt to use the frequency and spatial distribution of galaxies with specific morphological features to study the efficiency of various environmental effects on the evolution of disk galaxies in clusters. The velocity distribution of the barred spirals in the Virgo region is clearly different than that of the nonbarred spirals, suggesting that barred spirals are more common in the main condensation of the cluster. A sample cleansed of galaxies not belonging to the main cluster condensation using the subcluster assignments of Binggeli et al. [A&AS, 98, 275 (1993)] bears this out, showing that the radial distribution of barred spirals is more centrally condensed than that of nonbarred spirals. In contrast to the spiral galaxies, the distribution of barred S0 galaxies is statistically indistinguishable from that of nonbarred S0's. Consideration of the level of tidal perturbation due to the cluster mass distribution as compared to that due to individual galaxies suggests that tidal triggering by the cluster mass distribution is the most likely source of the enhanced fraction of barred spirals in the cluster center.

Victor Andersen

1996-03-22T23:59:59.000Z

90

PHAT STELLAR CLUSTER SURVEY. I. YEAR 1 CATALOG AND INTEGRATED PHOTOMETRY  

SciTech Connect (OSTI)

The Panchromatic Hubble Andromeda Treasury (PHAT) survey is an ongoing Hubble Space Telescope (HST) multi-cycle program to obtain high spatial resolution imaging of one-third of the M31 disk at ultraviolet through near-infrared wavelengths. In this paper, we present the first installment of the PHAT stellar cluster catalog. When completed, the PHAT cluster catalog will be among the largest and most comprehensive surveys of resolved star clusters in any galaxy. The exquisite spatial resolution achieved with HST has allowed us to identify hundreds of new clusters that were previously inaccessible with existing ground-based surveys. We identify 601 clusters in the Year 1 sample, representing more than a factor of four increase over previous catalogs within the current survey area (390 arcmin{sup 2}). This work presents results derived from the first {approx}25% of the survey data; we estimate that the final sample will include {approx}2500 clusters. For the Year 1 objects, we present a catalog with positions, radii, and six-band integrated photometry. Along with a general characterization of the cluster luminosities and colors, we discuss the cluster luminosity function, the cluster size distributions, and highlight a number of individually interesting clusters found in the Year 1 search.

Johnson, L. Clifton; Dalcanton, Julianne J.; Fouesneau, Morgan; Hodge, Paul W.; Weisz, Daniel R.; Williams, Benjamin F.; Beerman, Lori C. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Seth, Anil C. [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Caldwell, Nelson [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Gouliermis, Dimitrios A. [Institut fuer Theoretische Astrophysik, Zentrum fuer Astronomie der Universitaet Heidelberg, Albert-Ueberle-Strasse 2, D-69120 Heidelberg (Germany); Larsen, Soren S. [Department of Astrophysics, IMAPP, Radboud University Nijmegen, P.O. Box 9010, 6500 GL Nijmegen (Netherlands); Olsen, Knut A. G. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); San Roman, Izaskun; Sarajedini, Ata [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611-2055 (United States); Bianchi, Luciana [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Dolphin, Andrew E. [Raytheon Company, 1151 East Hermans Road, Tucson, AZ 85756 (United States); Girardi, Leo [Osservatorio Astronomico di Padova-INAF, Vicolo dell'Osservatorio 5, I-35122 Padova (Italy); Guhathakurta, Puragra [Department of Astronomy and Astrophysics, University of California Observatories/Lick Observatory, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States); Kalirai, Jason [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Lang, Dustin, E-mail: lcjohnso@astro.washington.edu [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); and others

2012-06-20T23:59:59.000Z

91

THE PANCHROMATIC HUBBLE ANDROMEDA TREASURY. III. MEASURING AGES AND MASSES OF PARTIALLY RESOLVED STELLAR CLUSTERS  

SciTech Connect (OSTI)

The apparent age and mass of a stellar cluster can be strongly affected by stochastic sampling of the stellar initial mass function (IMF), when inferred from the integrated color of low-mass clusters ({approx}<10{sup 4} M {sub Sun }). We use simulated star clusters to show that these effects are minimized when the brightest, rapidly evolving stars in a cluster can be resolved, and the light of the fainter, more numerous unresolved stars can be analyzed separately. When comparing the light from the less luminous cluster members to models of unresolved light, more accurate age estimates can be obtained than when analyzing the integrated light from the entire cluster under the assumption that the IMF is fully populated. We show the success of this technique first using simulated clusters, and then with a stellar cluster in M31. This method represents one way of accounting for the discrete, stochastic sampling of the stellar IMF in less massive clusters and can be leveraged in studies of clusters throughout the Local Group and other nearby galaxies.

Beerman, Lori C.; Johnson, L. Clifton; Fouesneau, Morgan; Dalcanton, Julianne J.; Weisz, Daniel R.; Williams, Ben F. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Seth, Anil C. [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Bell, Eric F. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Bianchi, Luciana C. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Caldwell, Nelson [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Dolphin, Andrew E. [Raytheon Company, 1151 East Hermans Road, Tucson, AZ 85756 (United States); Gouliermis, Dimitrios A. [Zentrum fuer Astronomie, Institut fuer Theoretische Astrophysik, Universitaet Heidelberg, Albert-Ueberle-Strasse 2, D-69120 Heidelberg (Germany); Kalirai, Jason S. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Larsen, Soren S. [Department of Astrophysics, IMAPP, Radboud University Nijmegen, P.O. Box 9010, NL-6500 GL Nijmegen (Netherlands); Melbourne, Jason L. [Caltech Optical Observatories, Division of Physics, Mathematics and Astronomy, Mail Stop 301-17, California Institute of Technology, Pasadena, CA 91125 (United States); Rix, Hans-Walter [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany); Skillman, Evan D., E-mail: beermalc@astro.washington.edu [Department of Astronomy, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States)

2012-12-01T23:59:59.000Z

92

White Dwarfs in Globular Clusters  

E-Print Network [OSTI]

We review empirical and theoretical findings concerning white dwarfs in Galactic globular clusters. Since their detection is a critical issue we describe in detail the various efforts to find white dwarfs in globular clusters. We then outline the advantages of using cluster white dwarfs to investigate the formation and evolution of white dwarfs and concentrate on evolutionary channels that appear to be unique to globular clusters. We also discuss the usefulness of globular cluster white dwarfs to provide independent information on the distances and ages of globular clusters, information that is very important far beyond the immediate field of white dwarf research. Finally, we mention possible future avenues concerning globular cluster white dwarfs, like the study of strange quark matter or plasma neutrinos.

S. Moehler; G. Bono

2011-06-30T23:59:59.000Z

93

CLUSTER LENSING PROFILES DERIVED FROM A REDSHIFT ENHANCEMENT OF MAGNIFIED BOSS-SURVEY GALAXIES  

SciTech Connect (OSTI)

We report the first detection of a redshift-depth enhancement of background galaxies magnified by foreground clusters. Using 300,000 BOSS survey galaxies with accurate spectroscopic redshifts, we measure their mean redshift depth behind four large samples of optically selected clusters from the Sloan Digital Sky Survey (SDSS) surveys, totaling 5000-15,000 clusters. A clear trend of increasing mean redshift toward the cluster centers is found, averaged over each of the four cluster samples. In addition, we find similar but noisier behavior for an independent X-ray sample of 158 clusters lying in the foreground of the current BOSS sky area. By adopting the mass-richness relationships appropriate for each survey, we compare our results with theoretical predictions for each of the four SDSS cluster catalogs. The radial form of this redshift enhancement is well fitted by a richness-to-mass weighted composite Navarro-Frenk-White profile with an effective mass ranging between M{sub 200} {approx} 1.4-1.8 Multiplication-Sign 10{sup 14} M{sub Sun} for the optically detected cluster samples, and M{sub 200} {approx} 5.0 Multiplication-Sign 10{sup 14} M{sub Sun} for the X-ray sample. This lensing detection helps to establish the credibility of these SDSS cluster surveys, and provides a normalization for their respective mass-richness relations. In the context of the upcoming bigBOSS, Subaru Prime Focus Spectrograph, and EUCLID-NISP spectroscopic surveys, this method represents an independent means of deriving the masses of cluster samples for examining the cosmological evolution, and provides a relatively clean consistency check of weak-lensing measurements, free from the systematic limitations of shear calibration.

Coupon, Jean; Umetsu, Keiichi [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China); Broadhurst, Tom, E-mail: coupon@asiaa.sinica.edu.tw [Department of Theoretical Physics, University of Basque Country UPV/EHU, P.O. Box 644, E-48080 Bilbao (Spain)

2013-07-20T23:59:59.000Z

94

FT-ICR Study of Precursor Clusters of Single Wall Carbon Nanotubes (SWNTs)  

E-Print Network [OSTI]

gas was injected to the nozzle. In the atmosphere of helium gas, vaporized atoms condensed to clusters vaporization of Ni/Co and Ni/Y doped graphite samples used for the macroscopic laser-oven production of SWNTs was drastically different. The chemical reaction of these clusters with NO gas was used as the probe

Maruyama, Shigeo

95

FT-ICR Study of Precursor Clusters of Single Wall Carbon Nanotubes (SWNTs)  

E-Print Network [OSTI]

of metal-doped carbon materials used for macroscopic production of endohedral metallofullerene or SWNTs. Four different sample materials were used in the cluster beam source. Two of them were composite disks with pure carbon clusters. On the other hand, NiCn - from Ni/Co-doped and Ni/Y-doped materials and Co

Maruyama, Shigeo

96

iVIBRATE: Interactive Visualization Based Framework for Clustering Large Datasets  

E-Print Network [OSTI]

iVIBRATE: Interactive Visualization Based Framework for Clustering Large Datasets Keke Chen Ling of large datasets continues to be one of the most important problems in large- scale data analysis. A commonly used methodology for cluster analysis on large datasets is the three-phase framework of "sampling

97

Clustering of SZ clusters on a past light-cone: acoustic oscillations and constraints on dark energy  

E-Print Network [OSTI]

In this paper we study the clustering of SZ-selected galaxy clusters on a past light-cone, particularly paying attention to the possibility of constraining properties of dark energy. The prospects of detecting baryonic features in the cluster power spectrum for a wide and shallow survey like PLANCK, and for an SPT-like narrow and deep survey are discussed. It is demonstrated that these future blank sky SZ surveys will have capability to improve significantly over the recently announced detection of baryonic oscillations based on the SDSS Luminous Red Galaxy (LRG) sample. We carry out parameter estimation using Fisher matrix approach taking into account the anisotropic nature of the power spectrum due to redshift space and cosmological distortions. The clustering signal which is not too sensitive to systematic uncertainties serves as a valuable piece of information that in combination with other sources of data helps in breaking degeneracies between the cosmological parameters.

G. Huetsi

2005-12-07T23:59:59.000Z

98

Structure and kinematics of galaxy clusters I. The redshift catalogue  

E-Print Network [OSTI]

An extensive redshift survey has been conducted on a sample of 15 nearby (0.01 < z < 0.05) clusters of galaxies. A total number of 860 redshifts were determined by fitting of emission--lines and/or cross-correlation techniques. Of this sample, 735 galaxies are within 0.2--0.8 Mpc ($H_0$ = 50 km/s/Mpc) of the center of clusters. Approximate morphological types are available for most of the galaxies. A comparison of the present redshifts with published data allows an extensive error analysis. The agreement is excellent with the most modern data, showing a zero point error of 5 km/s and an overall consistency of the measurements and their uncertainties. We estimate our redshifts to have mean random errors around 30 km/s. A population analysis of the clusters will be given in a forthcoming paper.

P. Stein

1996-01-12T23:59:59.000Z

99

PHOTOMETRIC PROPERTIES OF THE M33 STAR CLUSTER SYSTEM  

SciTech Connect (OSTI)

We present a catalog of 2990 extended sources in a 1{sup 0} x 1{sup 0} area centered on M33 using the MegaCam camera on the 3.6 m Canada-France-Hawaii Telescope. The catalog includes 599 new candidate stellar clusters, 204 previously confirmed clusters, 1969 likely background galaxies, and 218 unknown extended objects. We present ugriz integrated magnitudes of the candidates and confirmed star clusters (SCs) as well as the full width at half maximum, ellipticity, and stellarity. Based on the properties of the confirmed SCs, we select a sub-sample of highly probable clusters composed of 246 objects. The integrated photometry of the complete cluster catalog reveals a wide range of colors of -0.4 < (g - r) < 1.5 and -1.0 < (r - i) < 1.0 with no obvious cluster subpopulations. Comparisons with models of simple stellar populations suggest a large range of ages some as old as {approx}10 Gyr. In addition, we find a sequence in the color-color diagrams that deviates from the expected direction of evolution. This feature could be associated with very young clusters (<10{sup 7} yr) possessing significant nebular emission. Analysis of the radial density distribution suggests that the cluster system of M33 has suffered from significant depletion possibly due to interactions with M31. We also detect a gap in the cluster distribution in the color-color diagram at (g - r) {approx_equal} 0.3 and (u - g) {approx_equal} 0.8. This gap could be interpreted as an evolutionary effect. This complete catalog provides promising targets for deep photometry and high-resolution spectroscopy to study the structure and star formation history of M33.

San Roman, Izaskun; Sarajedini, Ata [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611-2055 (United States); Aparicio, Antonio, E-mail: izaskun@astro.ufl.ed, E-mail: ata@astro.ufl.ed, E-mail: antapaj@iac.e [Instituto de Astrofisica de Canarias, Via Lactea s/n. E-38205, La Laguna, Tenerife, Canary Islands (Spain)

2010-09-10T23:59:59.000Z

100

Clustering of Ultraluminous Infrared Galaxies in the Boötes Field  

E-Print Network [OSTI]

of these two samples are nearly indistinguishable, and they are consistent with the clustering of other massive galaxies at these redshifts. Therefore, we conclude that these objects occupy dark-matter haloes of similar mass, on the order of 5 x 1012M...

De Alba, Roberto

2010-07-14T23:59:59.000Z

Note: This page contains sample records for the topic "four-stage cluster sampling" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Topological clusters in SU(2) gluodynamics at finite T and  

E-Print Network [OSTI]

Topological clusters in SU(2) gluodynamics at finite T and the evidence for KvB calorons E'2005, Trinity College, Dublin July 25 to 30, 2005 #12;Overview Content · Introduction · The SU(2) KvB Caloron · Caloron-like Structures in Monte-Carlo Samples ? · A Stochastic Caloron Model · Summary

102

Constraints on Cluster Formation from Old Globular CLuster Systems  

E-Print Network [OSTI]

The properties of old globular cluster systems (GCSs) in galaxy halos offer unique insight into the physical processes that conspire to form any generic star cluster, at any epoch. Presented here is a summary of the information obtained from (1) the specific frequencies (total populations) and spatial structures (density vs. galactocentric radius) of GCSs in early-type galaxies, as they relate to the efficiency (or probability) of bound cluster formation, and (2) the fundamental role of a scaling between cluster mass and energy among Galactic globulars in setting their other structural correlations, and the possible implications for star formation efficiency as a function of mass in gaseous protoclusters.

Dean E. McLaughlin

2000-02-03T23:59:59.000Z

103

The interplay between radio galaxies and cluster environment  

E-Print Network [OSTI]

By combining the REFLEX and NORAS cluster datasets with the NVSS radio catalogue, we obtain a sample of 145, z<0.3, X-ray selected clusters brighter than 3 10^(-12) erg/s/cm^2 that show a central radio emission above 3 mJy. For virial masses M_vir<~10^(14.5) M_sun, 11 clusters out of 12 (corresponding to 92% of the systems) are inhabited by a central radio source. This fraction decreases with higher masses as M_vir^(-0.4) and suggests that the majority of X-ray selected clusters host in their centre a radio source brighter than about 10^(20) W/Hz/sr. A division of the sample into clusters harbouring either point-like or an extended radio-loud AGN reveals that the steepening of the L_X-T relation for low-temperature clusters is strongly associated with the presence of central radio objects with extended jets and/or lobe structures. In the latter case, L_X\\propto T^(4) while for point-like sources one recovers an approximately self-similar relation L_X\\propto T^(2.3). Monte Carlo simulations show that the steepening of the L_X-T relation is not caused by clusters being under-luminous in the X-ray band, but rather by overheating, most likely caused by the interplay between the extended radio structures and the intracluster medium. In the case of low-mass systems, we also find a tight correlation between radio luminosity and cluster temperature. The effects of the central radio source on the thermal state of a cluster become less important with increasing cluster mass. (Abridged) The luminosity distribution of the cluster radio population differs from that of all radio sources, as there is a deficit of low-luminosity (L_R<~10^(22) W/Hz/sr) objects, while the number of high-luminosity ones is boosted. The net effect on the radio luminosity function is of a flattening at all luminosities L_R<~ 10^(24) W/Hz/sr.

M. Magliocchetti; M. Bruggen

2007-05-04T23:59:59.000Z

104

The Cluster SZ -- Mass Correlation  

E-Print Network [OSTI]

N-body + hydrodynamic simulations of galaxy clusters are used to demonstrate a correlation between galaxy cluster mass and the strength of the Sunyaev-Zel'dovich (SZ) effect induced by the cluster. The intrinsic scatter in the correlaton is larger than seen in the cluster mass -- X-ray temperature correlation, but smaller than seen in the correlation between mass (or temperature) and X-ray luminosity, as expected. Using the convergence to self-similarity of cluster structure at larger radii, a simple area-averaged SZ value derived from mock SZ maps also correlates well with mass; the intrinsic scatter in this correlation is comparable to that seen in simulations for the mass -- temperature correlation. Such a relation may prove a powerful tool for estimating cluster masses at higher redshifts.

Christopher A. Metzler

1998-12-16T23:59:59.000Z

105

Cluster structures in Oxygen isotopes  

E-Print Network [OSTI]

Cluster structure of 16O,18O and 20O is investigated by the antisymmettrized molecular dynamics (AMD) plus generator coordinate method (GCM). We have found the K^{\\pi}=0$_2^+$ and 0$_1^-$ rotational bands of 18O that have the prominent 14C+\\alpha cluster structure. Clustering systematics becomes richer in 20O. We suggest the K^{\\pi}=0$_2^+$ band that is the mixture of the 12C+\\alpha+4n and 14C+6He cluster structures, and the K^{\\pi}=0$_1^-$ band that has the 14C+6He cluster structure. The K^{\\pi}=0$_3^+$ and 0$_2^-$ bands that have the prominent 16C+\\alpha cluster structure are also found.

N. Furutachi; M. kimura; A. Doté; Y. Kanada-En'yo; S. oryu

2007-06-01T23:59:59.000Z

106

Are Cluster Dwarfs Recycled Galaxies?  

E-Print Network [OSTI]

Although cluster dwarf galaxies are often neglected due to their faintness, recent observations demonstrate that they are critical for understanding the physical processes behind galaxy and cluster formation. Dwarfs are the most common galaxy type and are particularly abundant in clusters. Recent observational results suggest that dwarfs in dense environments do not all form early in the universe, as expected from hierarchical structure formation models. Many of these systems appear to be younger and more metal rich than dwarfs in lower density areas, suggesting they are possibly created by a tidal process. Several general galaxy cluster observations, including steep luminosity functions and the origin of intracluster light, are natural outcomes of these processes.

Christopher J. Conselice

2003-12-12T23:59:59.000Z

107

PDSF Cluster Statistics  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLas Conchas recoveryLaboratorySpeedingOptimizing I/OP-Glycoprotein StructureStatistics Cluster

108

Structure stability and spectroscopy of metal clusters  

SciTech Connect (OSTI)

Theory based on self-consistent field-linear combinations of atomic orbitals-molecular orbital theory was applied to clusters. Four areas were covered: electronic structure, equilibrium geometries, and stability of charged clusters, interaction of metal clusters with H and halogen atoms, thermal stability of isolated clusters, and stability and optical properties of hetero-atomic clusters. (DLC)

Not Available

1993-01-01T23:59:59.000Z

109

Cosmological Constraints from the SDSS maxBCG Cluster Catalog  

SciTech Connect (OSTI)

We use the abundance and weak lensing mass measurements of the SDSS maxBCG cluster catalog to simultaneously constrain cosmology and the richness-mass relation of the clusters. Assuming a flat {Lambda}CDM cosmology, we find {sigma}{sub 8}({Omega}{sub m}/0.25){sup 0.41} = 0.832 {+-} 0.033 after marginalization over all systematics. In common with previous studies, our error budget is dominated by systematic uncertainties, the primary two being the absolute mass scale of the weak lensing masses of the maxBCG clusters, and uncertainty in the scatter of the richness-mass relation. Our constraints are fully consistent with the WMAP five-year data, and in a joint analysis we find {sigma}{sub 8} = 0.807 {+-} 0.020 and {Omega}{sub m} = 0.265 {+-} 0.016, an improvement of nearly a factor of two relative to WMAP5 alone. Our results are also in excellent agreement with and comparable in precision to the latest cosmological constraints from X-ray cluster abundances. The remarkable consistency among these results demonstrates that cluster abundance constraints are not only tight but also robust, and highlight the power of optically-selected cluster samples to produce precision constraints on cosmological parameters.

Rozo, Eduardo; /CCAPP; Wechsler, Risa H.; /KIPAC, Menlo Park /SLAC; Rykoff, Eli S.; /UC, Santa Barbara; Annis, James T.; /Fermilab; Becker, Matthew R.; /Chicago U. /KICP, Chicago; Evrard, August E.; /Michigan U. /Michigan U., MCTP; Frieman, Joshua A.; /Fermilab /KICP, Chicago /Chicago U.; Hansen, Sarah M.; /UC, Santa Cruz; Hao, Jia; /Michigan U.; Johnston, David E.; /Northwestern U.; Koester, Benjamin P.; /KICP, Chicago /Chicago U.; McKay, Timothy A.; /Michigan U. /Michigan U., MCTP; Sheldon, Erin S.; /Brookhaven; Weinberg, David H.; /CCAPP /Ohio State U.

2009-08-03T23:59:59.000Z

110

Heating and cooling in the Perseus cluster core  

E-Print Network [OSTI]

It is well known that the radiative cooling time of the hot X-ray emitting gas in the cores of most clusters of galaxies is less than 10^10 yr. In many clusters the gas temperature also drops towards the centre. If we draw a causal connection between these two properties then we infer the presence of a cooling flow onto the central galaxy. High spectral resolution XMM-Newton data and high spatial resolution Chandra data, show however a lack of X-ray emitting gas below about one third of the cluster virial temperature. The explanation is that some form of heating balances cooling. The smoothness and similarity of the cooling time profiles and the flatness of the required heating profiles all indicate that we must seek a relatively gentle, quasi-continuous (on timescales heat source. The likely such source is the central black hole and its powerful jets which create bubble-like cavities in the inner hot gas. We briefly review the general heating and cooling statistics in an X-ray bright sample of cluster before we discuss the detailed situation in the Perseus cluster, the X-ray brightest cluster in the Sky.

A. C. Fabian; J. S. Sanders

2006-12-15T23:59:59.000Z

111

YOUNG RADIO PULSARS IN GALACTIC GLOBULAR CLUSTERS  

SciTech Connect (OSTI)

Currently three isolated radio pulsars and one binary radio pulsar with no evidence of any previous recycling are known in 97 surveyed Galactic globular clusters (GCs). As pointed out by Lyne et al., the presence of these pulsars cannot be explained by core-collapse supernovae, as commonly assumed for their counterparts in the Galactic disk. We apply a Bayesian analysis to the results from surveys for radio pulsars in GCs and find the number of potentially observable non-recycled radio pulsars present in all clusters to be <3600. Accounting for beaming and retention considerations, the implied birthrate for any formation scenario for all 97 clusters is <0.25 pulsars century{sup -1} assuming a Maxwellian distribution of velocities with a dispersion of 10 km s{sup -1}. The implied birthrates for higher velocity dispersions are substantially higher than inferred for such pulsars in the Galactic disk. This suggests that the velocity dispersion of young pulsars in GCs is significantly lower than those of disk pulsars. These numbers may be substantial overestimates due to the fact that the currently known sample of young pulsars is observed only in metal-rich clusters. We propose that young pulsars may only be formed in GCs with metallicities with log[Fe/H] > - 0.6. In this case, the potentially observable population of such young pulsars is 447{sup +1420}{sub -399} (the error bars give a 95% confidence interval) and their birthrate is 0.012{sup +0.037}{sub -0.010} pulsars century{sup -1}. The most likely creation scenario to explain these pulsars is the electron capture supernova of an OMgNe white dwarf.

Boyles, J.; Lorimer, D. R. [Department of Physics, 210 Hodges Hall, West Virginia University, Morgantown, WV 26506 (United States); Turk, P. J.; Mnatsakanov, R. [Department of Statistics, 423 Hodges Hall, West Virginia University, Morgantown, WV 26506 (United States); Lynch, R. S. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904 (United States); Ransom, S. M. [National Radio Astronomy Observatory, 520 Edgemont Rd, Charlottesville, VA (United States); Freire, P. C. [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel D-53121, Bonn (Germany); Belczynski, K. [Astronomical Observatory, University of Warsaw, AL Ujazdowskie 4,00-478, Warsaw (Poland)

2011-11-20T23:59:59.000Z

112

A Serendipitous Deep Cluster Survey from ROSAT--PSPC pointed observations  

E-Print Network [OSTI]

We present a deep X-ray selected sample of galaxy clusters which has been created from a serendipitous search in ROSAT-PSPC deep pointed observations at high galactic latitude. This survey, hereafter known as the ROSAT Deep Cluster Survey (RDCS), is being carried out utilizing a wavelet-based detection algorithm which, unlike other detection methods, is not biased against extended, low surface brightness sources. It is a flux-diameter limited sample that extends the X-ray flux limit of previous cluster surveys by more than one order of magnitude ($F_X \\ge 1\\cdot 10^{-14}\\rm erg\\, cm^{-2}s^{-1}$). The first results of the on-going optical follow-up program indicate a high success rate of identification. At the present, 38 clusters out of 80 candidates have been identified on a 26 deg$^2$ surveyed area. Recently measured redshifts confirm the nature of these systems as low-moderate redshift groups ($z\\simeq 0.2-0.3$) and intermediate to high redshift clusters ($z\\simeq 0.4-0.7$). We show X-ray and optical images of several clusters identified to date, discuss the X-ray properties of the sample and present preliminary results on the redshift distribution. The final sample will include $\\sim 100$ clusters covering and area of $\\sim 40$ deg$^2$.

P. Rosati

1995-09-09T23:59:59.000Z

113

Substructure Analysis of Selected Low Richness 2dFGRS Clusters of Galaxies  

E-Print Network [OSTI]

Complementary one-, two-, and three-dimensional tests for detecting the presence of substructure in clusters of galaxies are applied to recently obtained data from the 2dF Galaxy Redshift Survey. The sample of 25 clusters used in this study includes 16 clusters not previously investigated for substructure. Substructure is detected at or greater than the 99% CL level in at least one test for 21 of the 25 clusters studied here. From the results, it appears that low richness clusters commonly contain subclusters participating in mergers. About half of the clusters have two or more components within 0.5 h^{-1} Mpc of the cluster centroid, and at least three clusters (Abell 1139, Abell 1663, and Abell S333) exhibit velocity-position characteristics consistent with the presence of possible cluster rotation, shear, or infall dynamics. The geometry of certain features is consistent with influence by the host supercluster environments. In general, our results support the hypothesis that low richness clusters relax to structureless equilibrium states on very long dynamical time scales (if at all).

William S. Burgett; Michael M. Vick; David S. Davis; Matthew Colless; Roberto De Propris; Ivan Baldry; Carlton Baugh; Joss Bland-Hawthorn; Terry Bridges; Russell Cannon; Shaun Cole; Chris Collins; Warrick Couch; Nicholas Cross; Gavin Dalton; Simon Driver; George Efstathiou; Richard Ellis; Carlos Frenk; Karl Glazebrook; Edward Hawkins; Carole Jackson; Ofer Lahav; Ian Lewis; Stuart Lumsden; Steve Maddox; Darren Madgwick; Peder Norberg; John A. Peacock; Will Percival; Bruce Peterson; Will Sutherland; Keith Taylor

2004-05-03T23:59:59.000Z

114

CAIRNS: The Cluster And Infall Region Nearby Survey I. Redshifts and Mass Profiles  

E-Print Network [OSTI]

The CAIRNS (Cluster And Infall Region Nearby Survey) project is a spectroscopic survey of the infall regions surrounding eight nearby, rich, X-ray luminous clusters of galaxies. We collect 15665 redshifts (3471 new or remeasured) within \\sim 5-10 Mpc of the centers of the clusters, making it the largest study of the infall regions of clusters. We determine cluster membership and the mass profiles of the clusters based on the phase space distribution of the galaxies. All of the clusters display decreasing velocity dispersion profiles. The mass profiles are fit well by functional forms based on numerical simulations but exclude an isothermal sphere. Specifically, NFW and Hernquist models provide good descriptions of cluster mass profiles to their turnaround radii. Our sample shows that the predicted infall pattern is ubiquitous in rich, X-ray luminous clusters over a large mass range. The caustic mass estimates are in excellent agreement with independent X-ray estimates at small radii and with virial estimates at intermediate radii. The mean ratio of the caustic mass to the X-ray mass is 1.03\\pm0.11 and the mean ratio of the caustic mass to the virial mass (when corrected for the surface pressure term) is 0.93\\pm0.07. We further demonstrate that the caustic technique provides reasonable mass estimates even in merging clusters.

K. Rines; M. J. Geller; M. J. Kurtz; A. Diaferio

2003-06-25T23:59:59.000Z

115

THE ACS NEARBY GALAXY SURVEY TREASURY. X. QUANTIFYING THE STAR CLUSTER FORMATION EFFICIENCY OF NEARBY DWARF GALAXIES  

SciTech Connect (OSTI)

We study the relationship between the field star formation and cluster formation properties in a large sample of nearby dwarf galaxies. We use optical data from the Hubble Space Telescope and from ground-based telescopes to derive the ages and masses of the young (t{sub age} {approx}< 100 Myr) cluster sample. Our data provide the first constraints on two proposed relationships between the star formation rate (SFR) of galaxies and the properties of their cluster systems in the low SFR regime. The data show broad agreement with these relationships, but significant galaxy-to-galaxy scatter exists. In part, this scatter can be accounted for by simulating the small number of clusters detected from stochastically sampling the cluster mass function. However, this stochasticity does not fully account for the observed scatter in our data, suggesting that there may be true variations in the fraction of stars formed in clusters in dwarf galaxies. Comparison of the cluster formation and the brightest cluster in our sample galaxies also provide constraints on cluster destruction models.

Cook, David O.; Dale, Daniel A. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Seth, Anil C. [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Johnson, L. Clifton; Weisz, Daniel R.; Fouesneau, Morgan; Dalcanton, Julianne J. [Department of Astronomy, University of Washington, Seattle, WA 98195 (United States); Olsen, Knut A. G. [National Optical Astronomy Observatory, Tucson, AZ 85719 (United States); Engelbracht, Charles W., E-mail: dcook12@uwyo.edu [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)

2012-06-01T23:59:59.000Z

116

Completion Report for Well Cluster ER-6-1  

SciTech Connect (OSTI)

Well Cluster ER-6-1 was constructed for the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office in support of the Nevada Environmental Restoration Division at the Nevada Test Site, Nye County, Nevada. This work was initiated as part of the Groundwater Characterization Project, now known as the Underground Test Area Project. The well cluster is located in southeastern Yucca Flat. Detailed lithologic descriptions with stratigraphic assignments for Well Cluster ER-6-1 are included in this report. These are based on composite drill cuttings collected every 3 meters and conventional core samples taken below 639 meters, supplemented by geophysical log data. Detailed petrographic, chemical, and mineralogical studies of rock samples were conducted on 11 samples to resolve complex interrelationships between several of the Tertiary tuff units. Additionally, paleontological analyses by the U.S. Geological Survey confirmed the stratigraphic assignments below 539 meters within the Paleozoic sedimentary section. All three wells in the Well ER-6-1 cluster were drilled within the Quaternary and Tertiary alluvium section, the Tertiary volcanic section, and into the Paleozoic sedimentary section.

Bechtel Nevada

2004-10-01T23:59:59.000Z

117

Incremental Hierarchical Clustering of Text Documents  

E-Print Network [OSTI]

distribution is demonstrated. 1 Introduction Document clustering is an effective tool to manage informationIncremental Hierarchical Clustering of Text Documents by Nachiketa Sahoo Adviser: Jamie Callan May 5, 2006 Abstract Incremental hierarchical text document clustering algorithms are important

Gordon, Geoffrey J.

118

Architectural support for enhancing security in clusters  

E-Print Network [OSTI]

to security, numerous security loopholes in cluster servers come to the forefront. Clusters usually rely on Żrewalls for their security, but the Żrewalls cannot prevent all security attacks; therefore, cluster systems should be designed to be robust...

Lee, Man Hee

2009-05-15T23:59:59.000Z

119

The evolution of star clusters: The resolved-star approach  

E-Print Network [OSTI]

We present the first results of a new technique to detect, locate, and characterize young dissolving star clusters. Using HST/ACS archival images of the nearby galaxy IC2574, we performed stellar PSF photometry and selected the most massive stars as our first test sample. We used a group-finding algorithm on the selected massive stars to find cluster candidates. We then plot the color-magnitude diagrams for each group, and use stellar evolutionary models to estimate their age. So far, we found 79 groups with ages of up to about 100 Myr, displaying various sizes and densities.

Anne Pellerin; Martin J. Meyer; Jason Harris; Daniela Calzetti

2008-02-29T23:59:59.000Z

120

Clustering of floaters by waves  

E-Print Network [OSTI]

We study experimentally how waves affect distribution of particles that float on a water surface. We show that clustering of small particles in a standing wave is a nonlinear effect with the clustering time decreasing as the square of the wave amplitude. In a set of random waves, we show that small floaters concentrate on a multi-fractal set.

P. Denissenko; G. Falkovich; S. Lukaschuk

2005-11-22T23:59:59.000Z

Note: This page contains sample records for the topic "four-stage cluster sampling" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Relative Ages of Globular Clusters  

E-Print Network [OSTI]

Ages of extragalactic globular clusters can provide valuable insights into the formation and evolution of galaxies. In this contribution the photometric methods of age dating old globular cluster systems are summarised. The spectroscopic approach is reviewed with an emphasis of the right choice of age diagnostics. We present a new method of quantifying the relatively best age-sensitive spectroscopic index given the quality of a data set and a certain theoretical stellar synthesis model. The relatively best diagnostic plot is constructed from the set of Lick indices and used to age date globular clusters in several early-type galaxies which are part of a large spectroscopic survey of extragalactic globular cluster systems. We find that, independently of host galaxy, metal-poor ([Fe/H] 8 Gyr) and coeval. Metal-rich clusters show a wide range of ages from ~15 down to a few Gyr.

Thomas H. Puzia

2002-10-18T23:59:59.000Z

122

Atomically precise (catalytic) particles synthesized by a novel cluster deposition instrument  

SciTech Connect (OSTI)

We report a new high vacuum instrument which is dedicated to the preparation of well-defined clusters supported on model and technologically relevant supports for catalytic and materials investigations. The instrument is based on deposition of size selected metallic cluster ions that are produced by a high flux magnetron cluster source. The throughput of the apparatus is maximized by collecting and focusing ions utilizing a conical octupole ion guide and a linear ion guide. The size selection is achieved by a quadrupole mass filter. The new design of the sample holder provides for the preparation of multiple samples on supports of various sizes and shapes in one session. After cluster deposition onto the support of interest, samples will be taken out of the chamber for a variety of testing and characterization.

Yin, C.; Tyo, E. [Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States)] [Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Kuchta, K. [Extrel CMS, LLC, 575 Epsilon Dr. Suite 2, Pittsburgh, Pennsylvania 15238-2838 (United States)] [Extrel CMS, LLC, 575 Epsilon Dr. Suite 2, Pittsburgh, Pennsylvania 15238-2838 (United States); Issendorff, B. von [Physikalisches Institut, Universität Freiburg, Stefan-Meier Str. 21, D-79104 Freiburg (Germany)] [Physikalisches Institut, Universität Freiburg, Stefan-Meier Str. 21, D-79104 Freiburg (Germany); Vajda, S., E-mail: vajda@anl.gov [Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Nanoscience and Technology Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Institute for Molecular Engineering, The University of Chicago, 5747 South Ellis Avenue, Chicago, Illinois 60637 (United States); Department of Chemical and Environmental Engineering, School of Engineering and Applied Science, Yale University, 9 Hillhouse Avenue, New Haven, Connecticut 06520 (United States)

2014-05-07T23:59:59.000Z

123

E-Print Network 3.0 - adaptive cluster sampling Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

and Information Sciences 68 Proceedings of the 2010 Conference on Empirical Methods in Natural Language Processing, pages 346355, MIT, Massachusetts, USA, 9-11 October 2010. c...

124

Comparative clustering analysis of variable stars in the Hipparcos, OGLE Large Magellanic Cloud and CoRoT exoplanet databases  

E-Print Network [OSTI]

Context. Discovery of new variability classes in large surveys using multivariate statistics techniques such as clustering, relies heavily on the correct understanding of the distribution of known classes as point processes in parameter space. Aims. Our objective is to analyze the correspondence between the classical stellar variability types and the clusters found in the distribution of light curve parameters and colour indices of stars in the CoRoT exoplanet sample. The final aim is to help in the identification on new types of variability by first identifying the well known variables in the CoRoT sample. Methods. We apply unsupervised classification algorithms to identify clusters of variable stars from modes of the probability density distribution. We use reference variability databases (Hipparcos and OGLE) as a framework to calibrate the clustering methodology. Furthermore, we use the results from supervised classification methods to interpret the resulting clusters. Results.We interpret the clusters in ...

Sarro, L M; Aerts, C; López, M

2009-01-01T23:59:59.000Z

125

Fragmentation Energetics of Clusters Relevant to Atmospheric...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

of Clusters Relevant to Atmospheric New Particle Formation. Fragmentation Energetics of Clusters Relevant to Atmospheric New Particle Formation. Abstract: The exact mechanisms by...

126

Additive Manufacturing Cluster Strategy | ornl.gov  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Additive Manufacturing Cluster Strategy SHARE Additive Manufacturing Cluster Strategy As the nation's premier research laboratory, ORNL is one of the world's most capable resources...

127

Weak-strong clustering transition in renewing compressible flows  

E-Print Network [OSTI]

We investigate the statistical properties of Lagrangian tracers transported by a time-correlated compressible renewing flow. We show that the preferential sampling of the phase space performed by tracers yields significant differences between the Lagrangian statistics and its Eulerian counterpart. In particular, the effective compressibility experienced by tracers has a non-trivial dependence on the time correlation of the flow. We examine the consequence of this phenomenon on the clustering of tracers, focusing on the transition from the weak- to the strong-clustering regime. We find that the critical compressibility at which the transition occurs is minimum when the time correlation of the flow is of the order of the typical eddy turnover time. Further, we demonstrate that the clustering properties in time-correlated compressible flows are non-universal and are strongly influenced by the spatio-temporal structure of the velocity field.

Ajinkya Dhanagare; Stefano Musacchio; Dario Vincenzi

2014-11-01T23:59:59.000Z

128

Blue Straggler Stars in Galactic Open Clusters and the Simple Stellar Population Model  

E-Print Network [OSTI]

Blue straggler stars present as secure members in the Galactic open clusters form a major challenge to the conventional picture of evolutionary population synthesis based on the stellar evolution theory of single stars, as illustrated in our previous work. Expansion of our sample in the current work to include younger age clusters provides a larger data base to expose the question raised for the simple stellar population model. The working sample now includes 97 Galactic open clusters of ages ranging from 0.1 to several Gyrs. The contributions of blue straggler stars to the integrated light of the host clusters are calculated on an individual cluster base. A data base of observational constrained simple stellar population model is made which has a larger age coverage than our previous work. It is shown in this work that the general existence of blue stragglers in star clusters of our sample dramatically altered the predictions of convectional stellar population model in terms of spectral energy distribution. The integrated spectral energy distributions of the synthetic spectra of the clusters are enhanced towards shorter wavelengths, therefore the results of the present work will cast new lights in understanding the properties of stellar populations.

Y. Xin; L. Deng; Z. Han

2006-09-27T23:59:59.000Z

129

Determining $?$ from cluster correlation function  

E-Print Network [OSTI]

It is shown how data on the cluster correlation function can be used in order to reconstruct the density of the pregalactic density field on the cluster mass scale. The method is applied to the data on the cluster correlation amplitude -- richness dependence. The spectrum of the recovered density field has the same shape as the density field derived from data on the galaxy correlation function which is measured as function of linear scales. Matching the two amplitudes relates the mass to the comoving scale it contains and thereby leads to a direct determination of $\\Omega$. The resultant density parameter turns out to be $\\Omega$=0.25.

A. Kashlinsky

1998-06-17T23:59:59.000Z

130

GAMMA RAYS FROM STAR FORMATION IN CLUSTERS OF GALAXIES  

SciTech Connect (OSTI)

Star formation in galaxies is observed to be associated with gamma-ray emission, presumably from non-thermal processes connected to the acceleration of cosmic-ray nuclei and electrons. The detection of gamma rays from starburst galaxies by the Fermi Large Area Telescope (LAT) has allowed the determination of a functional relationship between star formation rate and gamma-ray luminosity. Since star formation is known to scale with total infrared (8-1000 {mu}m) and radio (1.4 GHz) luminosity, the observed infrared and radio emission from a star-forming galaxy can be used to quantitatively infer the galaxy's gamma-ray luminosity. Similarly, star-forming galaxies within galaxy clusters allow us to derive lower limits on the gamma-ray emission from clusters, which have not yet been conclusively detected in gamma rays. In this study, we apply the functional relationships between gamma-ray luminosity and radio and IR luminosities of galaxies derived by the Fermi Collaboration to a sample of the best candidate galaxy clusters for detection in gamma rays in order to place lower limits on the gamma-ray emission associated with star formation in galaxy clusters. We find that several clusters have predicted gamma-ray emission from star formation that are within an order of magnitude of the upper limits derived in Ackermann et al. based on non-detection by Fermi-LAT. Given the current gamma-ray limits, star formation likely plays a significant role in the gamma-ray emission in some clusters, especially those with cool cores. We predict that both Fermi-LAT over the course of its lifetime and the future Cerenkov Telescope Array will be able to detect gamma-ray emission from star-forming galaxies in clusters.

Storm, Emma M.; Jeltema, Tesla E.; Profumo, Stefano [Department of Physics, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States)

2012-08-20T23:59:59.000Z

131

PHAT Stellar Cluster Survey. II. Andromeda Project Cluster Catalog  

E-Print Network [OSTI]

We construct a stellar cluster catalog for the Panchromatic Hubble Andromeda Treasury (PHAT) survey using image classifications collected from the Andromeda Project citizen science website. We identify 2,753 clusters and 2,270 background galaxies within ~0.5 deg$^2$ of PHAT imaging searched, or ~400 kpc$^2$ in deprojected area at the distance of the Andromeda galaxy (M31). These identifications result from 1.82 million classifications of ~20,000 individual images (totaling ~7 gigapixels) by tens of thousands of volunteers. We show that our crowd-sourced approach, which collects >80 classifications per image, provides a robust, repeatable method of cluster identification. The high spatial resolution Hubble Space Telescope images resolve individual stars in each cluster and are instrumental in the factor of ~6 increase in the number of clusters known within the survey footprint. We measure integrated photometry in six filter passbands, ranging from the near-UV to the near-IR. PHAT clusters span a range of ~8 ma...

Johnson, L Clifton; Dalcanton, Julianne J; Wallace, Matthew L; Simpson, Robert J; Lintott, Chris J; Kapadia, Amit; Skillman, Evan D; Caldwell, Nelson; Fouesneau, Morgan; Weisz, Daniel R; Williams, Benjamin F; Beerman, Lori C; Gouliermis, Dimitrios A; Sarajedini, Ata

2015-01-01T23:59:59.000Z

132

The spatial evaluation of neighborhood clusters of birth defects  

SciTech Connect (OSTI)

Spatial statistics have recently been applied in epidemiology to evaluate clusters of cancer and birth defects. Their use requires a comparison population, drawn from the population at risk for disease, that may not always be readily available. In this dissertation the plausibility of using data on all birth defects, available from birth defects registries, as a surrogate for the spatial distribution of all live births in the analysis of clusters is assessed. Three spatial statistics that have been applied in epidemiologic investigations of clusters, nearest neighbor distance, average interpoint distance, and average distance to a fixed point, were evaluated by computer simulation for their properties in a unit square, and in a zip code region. Comparison of spatial distributions of live births and birth defects was performed by drawing samples of live births and birth defects from Santa Clara County, determining the street address at birth, geocoding this address and evaluating the resultant maps using various statistical techniques. The proposed method was then demonstrated on a previously confirmed cluster of oral cleft cases. All live births for the neighborhood were geocoded, as were all birth defects. Evaluation of this cluster using the nearest neighbor and average interpoint distance statistics was performed using randomization techniques with both the live births population and the birth defect population as comparison groups. 113 refs., 36 figs., 16 tabs.

Frisch, J.D.

1990-04-16T23:59:59.000Z

133

The BMW Deep X-ray Cluster Survey  

E-Print Network [OSTI]

We briefly describe the main features of the Brera Multi-Wavelet (BMW) survey of serendipitous X-ray clusters, based on the still unexploited ROSAT-HRI archival observations. Cluster candidates are selected from the general BMW catalogue of 20,000 sources based exclusively on their X-ray extension. Contrary to common wisdom, a clever selection of the HRI energy channels allows us to significantly reduce the background noise, thus greatly improving the ability to detect low surface-brightness sources as clusters. The resulting sample of ~250 candidates shows a very good sky coverage down to a flux \\~3x10^-14 erg/s/cm^2 ([0.5-2.0] keV band), i.e comparable to existing PSPC-based deep survey, with a particularly interesting area of ~100 sq.deg. around fluxes ~10^-13 erg/s/cm^2, i.e. where highly-luminous, rare systems at z~0.6-1 can be detected. At the same time, the superior angular resolution of the instrument should avoid biases against intrinsically small systems, while easing the identification process (e.g. by spotting blends and AGN contaminants). While about 20% of the candidates are already identified with groups/clusters at z0.5) bonafide cluster counterpart for ~80% of the targets.

L. Guzzo; A. Moretti; S. Campana; S. Covino; I. Dell'Antonio; D. Lazzati; M. Longhetti; E. Molinari; M. R. Panzera; G. Tagliaferri

2001-01-24T23:59:59.000Z

134

X-RAY PROPERTIES OF PREMAIN-SEQUENCE STARS IN THE ORION NEBULA CLUSTER WITH KNOWN ROTATION PERIODS  

E-Print Network [OSTI]

X-RAY PROPERTIES OF PRE­MAIN-SEQUENCE STARS IN THE ORION NEBULA CLUSTER WITH KNOWN ROTATION PERIODS Nebula Cluster (ONC) to study the X-ray properties of a large sample of pre­main-sequence (PMS) stars with optically determined rotation periods. Our goal is to elucidate the origins of X-rays in PMS stars

Barsony, Mary

135

Infrared spectroscopy of ionic clusters  

SciTech Connect (OSTI)

This thesis describes new experiments wherein the infrared vibrational predissociation spectra of a number of mass-selected ionic cluster systems have been obtained and analyzed in the 2600 to 4000 cm{sup {minus}1} region. The species studied include: the hydrated hydronium ions, H{sub 3}O{sup +} (H{sub 2}O){sub 3 {minus}10}, ammoniated ammonium ions, NH{sub 4}{sup +}(NH{sub 3}){sub 1 {minus}10} and cluster ions involving both water and ammonia around an ammonium ion core, (mixed clusters) NH{sub 4}{sup +}(NH{sub 3}){sub n}(H{sub 2}O){sub m} (n+m=4). In each case, the spectra reveal well resolved structures that can be assigned to transitions arising from the vibrational motions of both the ion core of the clusters and the surrounding neutral solvent molecules. 154 refs., 19 figs., 8 tabs.

Price, J.M. (California Univ., Berkeley, CA (USA). Dept. of Chemistry Lawrence Berkeley Lab., CA (USA))

1990-11-01T23:59:59.000Z

136

Multi-source contingency clustering  

E-Print Network [OSTI]

This thesis examines the problem of clustering multiple, related sets of data simultaneously. Given datasets which are in some way connected (e.g. temporally) but which do not necessarily share label compatibility, we ...

Bouvrie, Jacob V

2004-01-01T23:59:59.000Z

137

Clusters and the Cosmic Web  

E-Print Network [OSTI]

We discuss the intimate relationship between the filamentary features and the rare dense compact cluster nodes in this network, via the large scale tidal field going along with them, following the cosmic web theory developed Bond et al. The Megaparsec scale tidal shear pattern is responsible for the contraction of matter into filaments, and its link with the cluster locations can be understood through the implied quadrupolar mass distribution in which the clusters are to be found at the sites of the overdense patches. We present a new technique for tracing the cosmic web, identifying planar walls, elongated filaments and cluster nodes in the galaxy distribution. This will allow the practical exploitation of the concept of the cosmic web towards identifying and tracing the locations of the gaseous WHIM. These methods, the Delaunay Tessellation Field Estimator (DTFE) and the Morphology Multiscale Filter (MMF) find their basis in computational geometry and visualization.

Rien van de Weygaert

2006-07-24T23:59:59.000Z

138

Adhesive Gravitational Clustering  

E-Print Network [OSTI]

The notion of `adhesion' has been advanced for the phenomenon of stabilization of large-scale structure emerging from gravitational instability of a cold medium. Recently, the physical origin of adhesion has been identified: a systematic derivation of the equations of motion for the density and the velocity fields leads naturally to the key equation of the `adhesion approximation' - however, under a set of strongly simplifying assumptions. In this work, we provide an evaluation of the current status of adhesive gravitational clustering and a clear explanation of the assumptions involved. Furthermore, we propose systematic generalizations with the aim to relax some of the simplifying assumptions. We start from the general Newtonian evolution equations for self-gravitating particles on an expanding Friedmann background and recover the popular `dust model' (pressureless fluid), which breaks down after the formation of density singularities; then we investigate, in a unified framework, two other models which, under the restrictions referred to above, lead to the `adhesion approximation'. We apply the Eulerian and Lagrangian perturbative expansions to these new models and, finally, we discuss some non-perturbative results that may serve as starting points for workable approximations of non-linear structure formation in the multi-stream regime. In particular, we propose a new approximation that includes, in limiting cases, the standard `adhesion model' and the Eulerian as well as Lagrangian first-order approximations.

Thomas Buchert; Alvaro Dominguez

2005-06-21T23:59:59.000Z

139

Dust cluster explosion  

SciTech Connect (OSTI)

A model for the dust cluster explosion where micron/sub-micron sized particles are accelerated at the expense of plasma thermal energy, in the afterglow phase of a complex plasma discharge is proposed. The model is tested by molecular dynamics simulations of dust particles in a confining potential. The nature of the explosion (caused by switching off the discharge) and the concomitant dust acceleration is found to depend critically on the pressure of the background neutral gas. At low gas pressure, the explosion is due to unshielded Coulomb repulsion between dust particles and yields maximum acceleration, while in the high pressure regime it is due to shielded Yukawa repulsion and yields much feebler acceleration. These results are in agreement with experimental findings. Our simulations also confirm a recently proposed electrostatic (ES) isothermal scaling relation, P{sub E}{proportional_to}V{sub d}{sup -2} (where P{sub E} is the ES pressure of the dust particles and V{sub d} is the confining volume).

Saxena, Vikrant [School of Mathematics and Physics, Queen's University Belfast, Belfast, Northern Ireland (United Kingdom); Institute for Plasma Research, Bhat, Gandhinagar (India); Avinash, K. [Department of Physics and Astrophysics, University of Delhi, New Delhi (India); Sen, A. [Institute for Plasma Research, Bhat, Gandhinagar (India)

2012-09-15T23:59:59.000Z

140

Cluster Dynamics of Planetary Waves  

E-Print Network [OSTI]

The dynamics of nonlinear atmospheric planetary waves is determined by a small number of independent wave clusters consisting of a few connected resonant triads. We classified the different types of connections between neighboring triads that determine the general dynamics of a cluster. Each connection type corresponds to substantially different scenarios of energy flux among the modes. The general approach can be applied directly to various mesoscopic systems with 3-mode interactions, encountered in hydrodynamics, astronomy, plasma physics, chemistry, medicine, etc.

Elena Kartashova; Victor S. L'vov

2008-11-05T23:59:59.000Z

Note: This page contains sample records for the topic "four-stage cluster sampling" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Incremental Cluster-Based Retrieval using Compressed Cluster-Skipping Inverted Files  

E-Print Network [OSTI]

Incremental Cluster-Based Retrieval using Compressed Cluster-Skipping Inverted Files ISMAIL SENGOR ________________________________________________________________________ We propose a unique cluster-based retrieval (CBR) strategy using a new cluster-skipping inverted file for improving query processing efficiency. The new inverted file incorporates cluster membership and centroid

Can, Fazli

142

Incremental Cluster-Based Retrieval Using Compressed Cluster-Skipping Inverted Files  

E-Print Network [OSTI]

15 Incremental Cluster-Based Retrieval Using Compressed Cluster-Skipping Inverted Files ISMAIL cluster-based retrieval (CBR) strategy using a new cluster-skipping inverted file for improving query processing efficiency. The new inverted file incorporates cluster member- ship and centroid information along

Ulusoy, Ă?zgĂĽr

143

uvbyCaHbeta CCD Photometry of Clusters. V. The Metal-Deficient Open Cluster NGC 2243  

E-Print Network [OSTI]

CCD photometry on the intermediate-band uvbyCaHbeta system is presented for the metal-deficient open cluster, NGC 2243. Restricting the data to probable single members of the cluster using the CMD and the photometric indices alone generates a sample of 100 stars at the cluster turnoff. The average E(b-y) = 0.039 (0.003 s.e.m.) or E(B-V) = 0.055 (0.004 s.e.m.), where the errors refer to internal errors alone. With this reddening, [Fe/H] is derived from both m_1 and hk, using b-y and Hbeta as the temperature index. The agreement among the four approaches is excellent, leading to a final weighted average of [Fe/H] = -0.57 (0.03 s.e.m.) for the cluster, on a scale where the Hyades has [Fe/H] = +0.12. Using a combination of photometric and spectroscopic data, 27 probable cluster members are identified and used to delineate the red giant branch and a well-defined clump at V = 13.70, while eliminating the so-called second clump at V = 14.1. Interpolation between isochrones of appropriate [Fe/H] leads to an apparent ...

Anthony-Twarog, B J; Twarog, B A

2004-01-01T23:59:59.000Z

144

vbyCaHbeta CCD Photometry of Clusters. VI. The Metal-Deficient Open Cluster NGC 2420  

E-Print Network [OSTI]

CCD photometry on the intermediate-band vbyCaHbeta system is presented for the metal-deficient open cluster, NGC 2420. Restricting the data to probable single members of the cluster using the CMD and the photometric indices alone generates a sample of 106 stars at the cluster turnoff. The average E(b-y) = 0.03 +/- 0.003 (s.e.m.) or E(B-V) = 0.050 +/- 0.004 (s.e.m.), where the errors refer to internal errors alone. With this reddening, [Fe/H] is derived from both m1 and hk, using b-y and Hbeta as the temperature index. The agreement among the four approaches is reasonable, leading to a final weighted average of [Fe/H] = -0.37 +/- 0.05 (s.e.m.) for the cluster, on a scale where the Hyades has [Fe/H] = +0.12. When combined with the abundances from DDO photometry and from recalibrated low-resolution spectroscopy, the mean metallicity becomes [Fe/H] = -0.32 +/- 0.03. It is also demonstrated that the average cluster abundances based upon either DDO data or low-resolution spectroscopy are consistently reliable to 0....

Anthony-Twarog, B J; Cracraft, M; Twarog, B A; Anthony-Twarog, Barbara J.; Tanner, Delora; Cracraft, Misty; Twarog, Bruce A.

2005-01-01T23:59:59.000Z

145

POLYCYCLIC AROMATIC HYDROCARBONS, IONIZED GAS, AND MOLECULAR HYDROGEN IN BRIGHTEST CLUSTER GALAXIES OF COOL-CORE CLUSTERS OF GALAXIES  

SciTech Connect (OSTI)

We present measurements of 5-25 {mu}m emission features of brightest cluster galaxies (BCGs) with strong optical emission lines in a sample of nine cool-core clusters of galaxies observed with the Infrared Spectrograph on board the Spitzer Space Telescope. These systems provide a view of dusty molecular gas and star formation, surrounded by dense, X-ray-emitting intracluster gas. Past work has shown that BCGs in cool-core clusters may host powerful radio sources, luminous optical emission-line systems, and excess UV, while BCGs in other clusters never show this activity. In this sample, we detect polycyclic aromatic hydrocarbons (PAHs), extremely luminous, rotationally excited molecular hydrogen line emission, forbidden line emission from ionized gas ([Ne II] and [Ne III]), and infrared continuum emission from warm dust and cool stars. We show here that these BCGs exhibit more luminous forbidden neon and H{sub 2} rotational line emission than star-forming galaxies with similar total infrared luminosities, as well as somewhat higher ratios of 70 {mu}m/24 {mu}m luminosities. Our analysis suggests that while star formation processes dominate the heating of the dust and PAHs, a heating process consistent with suprathermal electron heating from the hot gas, distinct from star formation, is heating the molecular gas and contributing to the heating of the ionized gas in the galaxies. The survival of PAHs and dust suggests that dusty gas is somehow shielded from significant interaction with the X-ray gas.

Donahue, Megan; Mark Voit, G.; Hoffer, Aaron [Physics and Astronomy Department, Michigan State University, East Lansing, MI 48824 (United States); De Messieres, Genevieve E.; O'Connell, Robert W. [Astronomy Department, University of Virginia, Charlottesville, VA (United States); McNamara, Brian R. [Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 (Canada); Nulsen, Paul E. J., E-mail: donahue@pa.msu.edu, E-mail: voit@pa.msu.edu, E-mail: hofferaa@msu.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2011-05-01T23:59:59.000Z

146

uvbyCaHbeta CCD Photometry of Clusters. III. The Most Metal-Rich Open Cluster, NGC 6253  

E-Print Network [OSTI]

CCD photometry on the intermediate-band uvbyCaH-beta system is presented for the old open cluster, NGC 6253. Despite a high level of field star contamination due to its location toward the galactic center, combination of the data from the multiple color indices with the core cluster sample derived from radial star counts leads to the identification of a set of highly probable, single cluster members. Photometric analysis of a select sample of 71 turnoff stars produces a reddening value of E(b-y) = 0.190 +/-0.002 (s.e.m.) or E(B-V) = 0.260 +/- 0.003 (s.e.m.) from 71 stars. The metallicity indices, delta-m1 and delta-hk, both identify this cluster as the most metal-rich object studied on either system to date. Simple extrapolation of the available metallicity calibrations leads to [Fe/H] ranging from +0.7 to +0.9. Metal-rich isochrones with overshoot imply an age between 2.5 and 3.5 Gyr, with an apparent distance modulus between (m-M)= 11.6 and 12.2, depending upon the isochrones used. The improvement in the fi...

Twarog, B A; De Lee, N

2003-01-01T23:59:59.000Z

147

CN ANOMALIES IN THE HALO SYSTEM AND THE ORIGIN OF GLOBULAR CLUSTERS IN THE MILKY WAY  

SciTech Connect (OSTI)

We explore the kinematics and orbital properties of a sample of red giants in the halo system of the Milky Way that are thought to have formed in globular clusters based on their anomalously strong UV/blue CN bands. The orbital parameters of the CN-strong halo stars are compared to those of the inner- and outer-halo populations as described by Carollo et al., and to the orbital parameters of globular clusters with well-studied Galactic orbits. The CN-strong field stars and the globular clusters both exhibit kinematics and orbital properties similar to the inner-halo population, indicating that stripped or destroyed globular clusters could be a significant source of inner-halo field stars, and suggesting that both the CN-strong stars and the majority of globular clusters are primarily associated with this population.

Carollo, Daniela [Department of Physics and Astronomy-Astronomy, Astrophysics and Astrophotonic Research Center Macquarie University-North Ryde, 2109 NSW (Australia); Martell, Sarah L. [Australian Astronomical Observatory, North Ryde, 2109 NSW (Australia); Beers, Timothy C. [National Optical Astronomy Observatory, Tucson, AZ 85719 (United States); Freeman, Ken C., E-mail: daniela.carollo@mq.edu.au, E-mail: smartell@aao.gov.au, E-mail: beers@noao.edu, E-mail: kcf@mso.anu.edu.au [Research School of Astronomy and Astrophysics, Australian National University and Mount Stromlo Observatory, Cotter Road, Weston, ACT 2611 (Australia)

2013-06-01T23:59:59.000Z

148

A neural network clustering algorithm for the ATLAS silicon pixel detector  

E-Print Network [OSTI]

A novel technique to identify and split clusters created by multiple charged particles in the ATLAS pixel detector using a set of artificial neural networks is presented. Such merged clusters are a common feature of tracks originating from highly energetic objects, such as jets. Neural networks are trained using Monte Carlo samples produced with a detailed detector simulation. This technique replaces the former clustering approach based on a connected component analysis and charge interpolation. The performance of the neural network splitting technique is quantified using data from proton--proton collisions at the LHC collected by the ATLAS detector in 2011 and from Monte Carlo simulations. This technique reduces the number of clusters shared between tracks in highly energetic jets by up to a factor of three. It also provides more precise position and error estimates of the clusters in both the transverse and longitudinal impact parameter resolution.

ATLAS collaboration

2014-06-30T23:59:59.000Z

149

Pinpointing Sheets for the Standard Cross-Cultural Sample: Complete Edition  

E-Print Network [OSTI]

7/27/68) Sampling Province 199: Patagonia. Representative ofof Cluster 391: Tehuelche (Patagonia), Sg4:349. Focus: Theoccupied the steppes of Patagonia in Argentina from the Rio

White, Douglas R.

2009-01-01T23:59:59.000Z

150

E-Print Network 3.0 - autonomous firing pattern Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Search Powered by Explorit Topic List Advanced Search Sample search results for: autonomous firing pattern Page: << < 1 2 3 4 5 > >> 1 Cluster Computing 9, 517, 2006 C 2006...

151

The Two-Point Correlation Function of Rich Clusters of Galaxies: Results from an Extended APM Cluster Redshift Survey  

E-Print Network [OSTI]

We present new estimates of the spatial two-point correlation function of rich clusters of galaxies selected from the APM Galaxy Survey. We have measured redshifts for a sample of $364$ clusters out to a depth of $\\sim 450\\hmpc$. The clusters have a mean space density of $\\bar{n} = 3.4\\times 10^{-5}\\hmpccc$. The two-point correlation function, $\\xi_{cc}$, for this sample is equal to unity at a pair-separation of $r_0 = 14.3\\pm1.75\\hmpc$ (2$\\sigma$ errors), consistent with our earlier results from a smaller sample. The new observations provide an accurate determination of the shape of $\\xi_{cc}$ to pair-separations of about $50\\hmpc$. Our results show that $\\xi_{cc}$ has a higher amplitude than expected according to the standard $\\Omega=1$ cold dark matter (CDM) model on spatial scales $2\\simlt s \\simlt 50\\hmpc$, but are in good agreement with scale-invariant fluctuations in either a low density CDM model or a critical density universe made up of a mixture of hot and cold dark matter. Our results provide strong constraints on so called `co-operative' models of galaxy formation in which the galaxy formation process introduces large-scale structure in the galaxy distribution.

G. B. Dalton; R. A. C. Croft; G. Efstathiou; W. J. Sutherland; S. J. Maddox; M. Davis

1994-07-25T23:59:59.000Z

152

THE CLUSTERED NATURE OF STAR FORMATION. PRE-MAIN-SEQUENCE CLUSTERS IN THE STAR-FORMING REGION NGC 602/N90 IN THE SMALL MAGELLANIC CLOUD  

SciTech Connect (OSTI)

Located at the tip of the wing of the Small Magellanic Cloud (SMC), the star-forming region NGC 602/N90 is characterized by the H II nebular ring N90 and the young cluster of pre-main-sequence (PMS) and early-type main-sequence stars NGC 602, located in the central area of the ring. We present a thorough cluster analysis of the stellar sample identified with Hubble Space Telescope/Advanced Camera for Surveys in the region. We show that apart from the central cluster low-mass PMS stars are congregated in 13 additional small, compact sub-clusters at the periphery of NGC 602, identified in terms of their higher stellar density with respect to the average background density derived from star counts. We find that the spatial distribution of the PMS stars is bimodal, with an unusually large fraction ({approx}60%) of the total population being clustered, while the remaining is diffusely distributed in the intercluster area, covering the whole central part of the region. From the corresponding color-magnitude diagrams we disentangle an age difference of {approx}2.5 Myr between NGC 602 and the compact sub-clusters, which appear younger, on the basis of comparison of the brighter PMS stars with evolutionary models, which we accurately calculated for the metal abundance of the SMC. The diffuse PMS population appears to host stars as old as those in NGC 602. Almost all detected PMS sub-clusters appear to be centrally concentrated. When the complete PMS stellar sample, including both clustered and diffused stars, is considered in our cluster analysis, it appears as a single centrally concentrated stellar agglomeration, covering the whole central area of the region. Considering also the hot massive stars of the system, we find evidence that this agglomeration is hierarchically structured. Based on our findings, we propose a scenario according to which the region NGC 602/N90 experiences an active clustered star formation for the last {approx}5 Myr. The central cluster NGC 602 was formed first and rapidly started dissolving into its immediate ambient environment, possibly ejecting also massive stars found away from its center. Star formation continued in sub-clusters of a larger stellar agglomeration, introducing an age spread of the order of 2.5 Myr among the PMS populations.

Gouliermis, Dimitrios A.; Gennaro, Mario [Max Planck Institute for Astronomy, Koenigstuhl 17, 69117 Heidelberg (Germany); Schmeja, Stefan [Zentrum fuer Astronomie der Universitaet Heidelberg, Institut fuer Theoretische Astrophysik, Albert-Ueberle-Str. 2, 69120 Heidelberg (Germany); Dolphin, Andrew E. [Raytheon Company, P.O. Box 11337, Tucson, AZ 85734 (United States); Tognelli, Emanuele; Prada Moroni, Pier Giorgio [Dipartimento di Fisica 'Enrico Fermi', Universita di Pisa, largo Pontecorvo 3, Pisa I-56127 (Italy)

2012-03-20T23:59:59.000Z

153

Are Cluster Magnetic Fields Primordial ?  

E-Print Network [OSTI]

We present results of a detailed and fully non-linear numerical and analytical investigation of magnetic field evolution from the very earliest cosmic epochs to the present. We find that, under reasonable assumptions concerning the efficiency of a putative magnetogenesis era during cosmic phase transitions, surprisingly strong magnetic fields 10^{-13} - 10^{-11} Gauss, on comparatively small scales 100 pc - 10 kpc may survive to the present. Building on prior work on the evolution of magnetic fields during the course of gravitational collapse of a cluster, which indicates that pre-collapse fields of 4\\times 10^{-12} Gauss extant on small scales may suffice to produce clusters with acceptable Faraday rotation measures, we question the widely hold view that cluster magnetic fields may not be entirely of primordial origin.

Robi Banerjee; Karsten Jedamzik

2004-09-07T23:59:59.000Z

154

Hysteretic clustering in granular gas  

E-Print Network [OSTI]

Granular material is vibro-fluidized in N=2 and N=3 connected compartments, respectively. For sufficiently strong shaking the granular gas is equi-partitioned, but if the shaking intensity is lowered, the gas clusters in one compartment. The phase transition towards the clustered state is of 2nd order for N=2 and of 1st order for N=3. In particular, the latter is hysteretic. The experimental findings are accounted for within a dynamical model that exactly has the above properties.

Ko van der Weele; Devaraj van der Meer; Michel Versluis; Detlef Lohse

2001-03-15T23:59:59.000Z

155

The Herschel Virgo Cluster Survey XVI: a cluster inventory  

E-Print Network [OSTI]

Herschel FIR observations are used to construct Virgo cluster galaxy luminosity functions and to show that the cluster lacks the very bright and the numerous faint sources detected in field galaxy surveys. The far-infrared SEDs are fitted to obtain dust masses and temperatures and the dust mass function. The cluster is over dense in dust by about a factor of 100 compared to the field. The same emissivity (beta) temperature relation applies for different galaxies as that found for different regions of M31. We use optical and HI data to show that Virgo is over dense in stars and atomic gas by about a factor of 100 and 20 respectively. Metallicity values are used to measure the mass of metals in the gas phase. The mean metallicity is about 0.7 solar and 50% of the metals are in the dust. For the cluster as a whole the mass density of stars in galaxies is 8 times that of the gas and the gas mass density is 130 times that of the metals. We use our data to consider the chemical evolution of the individual galaxies,...

Davies, J I; Baes, M; Bendo, G J; Clemens, M; De Looze, I; Alighieri, S di Serego; Fritz, J; Fuller, C; Pappalardo, C; Hughes, T M; Madden, S; Smith, M W L; Verstappen, J; Vlahakis, C

2013-01-01T23:59:59.000Z

156

Cosmological constraints from the correlation function of galaxy clusters  

E-Print Network [OSTI]

I compare various semi-analytic models for the bias of dark matter halos with halo clustering properties observed in recent numerical simulations. The best fitting model is one based on the collapse of ellipsoidal perturbations proposed by Sheth, Mo & Tormen (1999), which fits the halo correlation length to better than 8 per cent accuracy. Using this model, I confirm that the correlation length of clusters of a given separation depends primarily on the shape and amplitude of mass fluctuations in the universe, and is almost independent of other cosmological parameters. Current observational uncertainties make it difficult to draw robust conclusions, but for illustrative purposes I discuss the constraints on the mass power spectrum which are implied by recent analyses of the APM cluster sample. I also discuss the prospects for improving these constraints using future surveys such as the Sloan Digital Sky Survey. Finally, I show how these constraints can be combined with observations of the cluster number abundance to place strong limits on the matter density of the universe.

James Robinson

2000-04-03T23:59:59.000Z

157

Perspectives for logistics clusters development in Russia  

E-Print Network [OSTI]

This thesis is a normative work aimed at identifying locations in Russia with high, medium and unclear potentials for logistics cluster development. As a framework this work uses four different models of logistics clusters: ...

Tantsuyev, Andriy

2012-01-01T23:59:59.000Z

158

Flexi-Cluster: A Simulator for a Single Compute Cluster Flexi-Cluster is a flexible, discrete-event simulation model for a single compute cluster,  

E-Print Network [OSTI]

-event simulation model for a single compute cluster, such as might be deployed within a compute grid. The model

159

Lecture outline Densitybased clustering (DBScan)  

E-Print Network [OSTI]

point if for distance Eps : ­ |NEps(p)={q | dist(p,q) points: Not a core or a border point #12;Core, border and noise points Eps Eps Eps #12;Core, Border and Noise points Original Points Point types: core, border and noise Eps = 10, MinPts = 4 #12;Clusters

Terzi, Evimaria

160

An Improved Cluster Richness Estimator  

SciTech Connect (OSTI)

Minimizing the scatter between cluster mass and accessible observables is an important goal for cluster cosmology. In this work, we introduce a new matched filter richness estimator, and test its performance using the maxBCG cluster catalog. Our new estimator significantly reduces the variance in the L{sub X}-richness relation, from {sigma}{sub lnL{sub X}}{sup 2} = (0.86 {+-} 0.02){sup 2} to {sigma}{sub lnL{sub X}}{sup 2} = (0.69 {+-} 0.02){sup 2}. Relative to the maxBCG richness estimate, it also removes the strong redshift dependence of the richness scaling relations, and is significantly more robust to photometric and redshift errors. These improvements are largely due to our more sophisticated treatment of galaxy color data. We also demonstrate the scatter in the L{sub X}-richness relation depends on the aperture used to estimate cluster richness, and introduce a novel approach for optimizing said aperture which can be easily generalized to other mass tracers.

Rozo, Eduardo; /Ohio State U.; Rykoff, Eli S.; /UC, Santa Barbara; Koester, Benjamin P.; /Chicago U. /KICP, Chicago; McKay, Timothy; /Michigan U.; Hao, Jiangang; /Michigan U.; Evrard, August; /Michigan U.; Wechsler, Risa H.; /SLAC; Hansen, Sarah; /Chicago U. /KICP, Chicago; Sheldon, Erin; /New York U.; Johnston, David; /Houston U.; Becker, Matthew R.; /Chicago U. /KICP, Chicago; Annis, James T.; /Fermilab; Bleem, Lindsey; /Chicago U.; Scranton, Ryan; /Pittsburgh U.

2009-08-03T23:59:59.000Z

Note: This page contains sample records for the topic "four-stage cluster sampling" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

DESIGN OF CLUSTERED SUPERSCALAR MICROARCHITECTURES  

E-Print Network [OSTI]

DESIGN OF CLUSTERED SUPERSCALAR MICROARCHITECTURES Joan-Manuel Parcerisa Departament d'Arquitectura SUPERSCALAR MICROARCHITECTURES Joan-Manuel Parcerisa Departament d'Arquitectura de Computadors Universitat après tantes coses sobre l'ofici de la recerca, i sobre l'arquitectura de computadors al llarg d

Parcerisa, Joan-Manuel

162

Spectral Clustering of Synchronous Spike Trains 1 Spectral Clustering of Synchronous  

E-Print Network [OSTI]

Spectral Clustering of Synchronous Spike Trains 1 Spectral Clustering of Synchronous Spike Trains, University of Florida #12;Spectral Clustering of Synchronous Spike Trains 2 Outline Introduction Distance between two spike trains Clustering algorithm Results António Paiva, Sudhir Rao, Il Park and José Príncipe

Paiva, AntĂłnio R. C.

163

uvbyCa H beta CCD Photometry of Clusters. VII. The Intermediate-Age Anticenter Cluster Melotte 71  

E-Print Network [OSTI]

CCD photometry on the intermediate-band uvbyCa H beta system is presented for the anticenter, intermediate-age open cluster, Melotte 71. Restricting the data to probable single members of the cluster using the color-magnitude diagram and the photometric indices alone generates a sample of 48 F dwarfs on the unevolved main sequence. The average E(b-y) = 0.148 +/- 0.003 (s.e.m.) or E(B-V) = 0.202 +/- 0.004 (s.e.m.), where the errors refer to internal errors alone. With this reddening, [Fe/H] is derived from both m1 and hk, using H beta and b-y as the temperature index, with excellent agreement among the four approaches and a final weighted average of [Fe/H] = -0.17 +/- 0.02 (s.e.m.) for the cluster, on a scale where the Hyades has [Fe/H] = +0.12. When adjusted for the higher reddening estimate, the previous metallicity estimates from Washington photometry and from spectroscopy are now in agreement with the intermediate-band result. From comparisons to isochrones of appropriate metallicity, the cluster age and d...

Twarog, B A; Corder, S

2006-01-01T23:59:59.000Z

164

ESPC IDIQ Contract Sample  

Broader source: Energy.gov [DOE]

Document displays a sample indefinite delivery, indefinite quantity (IDIQ) energy savings performance contract (ESPC).

165

THE X-RAY-OPTICAL RELATIONS FOR NINE CLUSTERS AT z = 0.7-1.1 FROM THE ORELSE SURVEY  

SciTech Connect (OSTI)

We use Chandra observations of nine optically and X-ray-selected clusters in five different structures at z {approx} 0.7-1.1 from the Observations of Redshift Evolution in Large-Scale Environments survey to study diffuse X-ray emission from galaxy clusters. X-ray gas temperatures and bolometric rest-frame luminosities are measured for each cluster in the sample. We present new redshift measurements, derived from data obtained using the Deep Imaging Multi-Object Spectrograph on the Keck 10 m telescope, for two clusters in the RX J0910 supercluster at z {approx} 1.1, from which velocity dispersions are measured. Dispersions for all clusters are combined with X-ray luminosities and gas temperatures to evaluate how the cluster properties compare to low-redshift scaling relations. We also measure the degree of substructure in each cluster by examining the velocity histograms, performing Dressler-Shectman tests, and computing the offsets between the X-ray emission center and optically derived centroids. We find that only two clusters show clear indications of being unrelaxed, based on their scaling relations and other dynamical state diagnostics. Using our sample, we evaluate the redshift evolution of the L{sub x} -T relation and investigate the implications of our results for precision cosmology surveys.

Rumbaugh, N.; Lubin, L. M.; Fassnacht, C. D. [Department of Physics, University of California, Davis, 1 Shields Avenue, Davis, CA 95616 (United States)] [Department of Physics, University of California, Davis, 1 Shields Avenue, Davis, CA 95616 (United States); Kocevski, D. D. [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506-0055 (United States)] [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506-0055 (United States); Gal, R. R. [Institute for Astronomy, University of Hawai'i, 2680 Woodlawn Drive, HI 96822 (United States)] [Institute for Astronomy, University of Hawai'i, 2680 Woodlawn Drive, HI 96822 (United States); Lemaux, B. C. [CNRS, LAM (Laboratoire d'Astrophysique de Marseille), Aix Marseille Universite, UMR 7326, F-13388 Marseille (France)] [CNRS, LAM (Laboratoire d'Astrophysique de Marseille), Aix Marseille Universite, UMR 7326, F-13388 Marseille (France); Squires, G. K., E-mail: narumbaugh@ucdavis.edu [Spitzer Space Center, California Institute of Technology, M/S 220-6, 1200 East California Boulevard, Pasadena, CA 91125 (United States)

2013-02-15T23:59:59.000Z

166

Effervescent heating: constraints from nearby cooling flow clusters observed with XMM-Newton  

E-Print Network [OSTI]

We have used deprojected radial density and temperature profiles of a sample of 16 nearby CF clusters observed with XMM-Newton to test whether the effervescent heating model can satisfactorily explain the dynamics of CF clusters. For each cluster we derived the required extra heating as a function of cluster-centric distance for various values of the unknown parameters $\\dot M$ (mass deposition rate) and $f_c$ (conduction efficiency). We fitted the extra heating curve using the AGN effervescent heating function and derived the AGN parameters $L$ (the time-averaged luminosity) and $r_0$ (the scale radius where the bubbles start rising in the ICM). While we do not find any solution with the effervescent heating model for only one object, we do show that AGN and conduction heating are not cooperating effectively for half of the objects in our sample. For most of the clusters we find that, when a comparison is possible, the derived AGN scale radius $r_0$ and the observed AGN jet extension have the same order of magnitude. The AGN luminosities required to balance radiative losses are substantially lowered if the fact that the AGN deposits energy within a finite volume is taken into account. For the Virgo cluster, we find that the AGN power derived from the effervescent heating model is in good agreement with the observed jet power.

Rocco Piffaretti; Jelle Kaastra

2006-02-16T23:59:59.000Z

167

Cluster radioactivities from an island of cluster emitters  

SciTech Connect (OSTI)

We have recently developed a realistic model for studying cluster radioactivities from actinide nuclei. This model uses a cubic potential in the overlapping region connected by a Yukawa-plus-exponential potential in the post-scission region. In the present work we use this model to study {sup 4}He, {sup 12}C, {sup 16}O, and {sup 28}Si radioactivities in the region of nuclides with proton and neutron number in the range {ital Z}=56--64 and {ital N}=58--72, which has been recently identified by Poenaru {ital et} {ital al}. as a new island of such cluster emitters. It is found that charge equilibration is not needed in the study of these radioactivities and the half-lives obtained for these decays lie very close to those reported by Poenaru {ital et} {ital al}. using their analytical super asymmetric fission model.

Shanmugam, G.; Carmel Vigila Bai, G.M. [Department of Physics, Manonmaniam Sundaranar University, Tirunelveli 627 002 (India)] [Department of Physics, Manonmaniam Sundaranar University, Tirunelveli 627 002 (India); Kamalaharan, B. [Department of Physics, Presidency College, Madras 600 005 (India)] [Department of Physics, Presidency College, Madras 600 005 (India)

1995-05-01T23:59:59.000Z

168

The structure of star clusters in the outer halo of M31  

E-Print Network [OSTI]

We present a structural analysis of halo star clusters in M31 based on deep Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) imaging. The clusters in our sample span a range in galactocentric projected distance from 13 to 100 kpc and thus reside in rather remote environments. Ten of the clusters are classical globulars, while four are from the Huxor et al. (2005, 2008) population of extended, old clusters. For most clusters, contamination by M31 halo stars is slight, and so the profiles can be mapped reliably to large radial distances from their centres. We find that the extended clusters are well fit by analytic King (1962) profiles with ~20 parsec core radii and ~100 parsec photometric tidal radii, or by Sersic profiles of index ~1 (i.e. approximately exponential). Most of the classical globulars also have large photometric tidal radii in the range 50-100 parsec, however the King profile is a less good fit in some cases, particularly at small radii. We find 60 of the classical globular cluster...

Tanvir, N R; Ferguson, A M N; Huxor, A; Read, J I; Lewis, G F; Irwin, M J; Chapman, S; Ibata, R; Wilkinson, M I; McConnachie, A W; Martin, N F; Davies, M B; Bridges, T J

2012-01-01T23:59:59.000Z

169

Submillimetre sources in rich cluster fields - source counts, redshift estimates, and cooling flow limits  

E-Print Network [OSTI]

Recent submillimetre surveys have revealed a population of dusty, high redshift sources of great cosmological significance for understanding dust-enshrouded star formation in distant galaxies, and for determining the origin of the far-IR background. In this paper, we analyze nine rich cluster fields mapped at 850 and 450 microns with the SCUBA array on the James Clerk Maxwell telescope. Lensing models of the clusters are developed in order to derive accurate source counts for our sample. VLA maps of the same clusters are used to help constrain the redshift distribution of our SCUBA detections. Implications for high redshift galaxies and for the far-IR background are discussed. We also provide limits on distributed dust produced by cooling flows in these clusters.

Scott C. Chapman; Douglas Scott; Colin Borys; Gregory G. Fahlman

2000-09-05T23:59:59.000Z

170

Periodic Cluster Mutations and Related Integrable Maps  

E-Print Network [OSTI]

One of the remarkable properties of cluster algebras is that any cluster, obtained from a sequence of mutations from an initial cluster, can be written as a Laurent polynomial in the initial cluster (known as the "Laurent phenomenon"). There are many nonlinear recurrences which exhibit the Laurent phenomenon and thus unexpectedly generate integer sequences. The mutation of a typical quiver will not generate a recurrence, but rather an erratic sequence of exchange relations. How do we "design" a quiver which gives rise to a given recurrence? A key role is played by the concept of "periodic cluster mutation", introduced in 2009. Each recurrence corresponds to a finite dimensional map. In the context of cluster mutations, these are called "cluster maps". What properties do cluster maps have? Are they integrable in some standard sense? In this review I describe how integrable maps arise in the context of cluster mutations. I first explain the concept of "periodic cluster mutation", giving some classification results. I then give a review of what is meant by an integrable map and apply this to cluster maps. Two classes of integrable maps are related to interesting monodromy problems, which generate interesting Poisson algebras of functions, used to prove complete integrability and a linearisation. A connections to the Hirota-Miwa equation is explained.

Allan P Fordy

2014-03-31T23:59:59.000Z

171

Clustering Fossils in Solid Inflation  

E-Print Network [OSTI]

In solid inflation the single field non-Gaussianity consistency condition is violated. As a result, the long tensor perturbation induces observable clustering fossils in the form of quardupole anisotropy in large scale structure power spectrum. In this work we revisit the bispectrum analysis for the scalar-scalar-scalar and tensor-scalar-scalar for the general parameter space of solid. We consider the parameter space of the model in which the level of non-Gaussianity generated is consistent with Planck constraints. Specializing to this allowed range of model parameter, we calculate the quadrupole anisotropy induced from the long tensor perturbations on the power spectrum of scalar perturbations. We argue that imprints of clustering fossil from primordial gravitational waves on large scale structures can be detected from the future galaxy surveys.

Mohammad Akhshik

2014-09-10T23:59:59.000Z

172

The Kinematics and Dynamics of the Globular Clusters and the Planetary Nebulae of NGC 5128  

E-Print Network [OSTI]

A new kinematic and dynamic study of the halo of the giant elliptical galaxy, NGC 5128, is presented. From a spectroscopically confirmed sample of 340 globular clusters and 780 planetary nebulae, the rotation amplitude, rotation axis, velocity dispersion, and the total dynamical mass are determined for the halo of NGC 5128. The globular cluster kinematics were searched for both radial dependence and metallicity dependence by subdividing the globular cluster sample into 158 metal-rich ([Fe/H] > -1.0) and 178 metal-poor ([Fe/H] < -1.0) globular clusters. Our results show the kinematics of the metal-rich and metal-poor subpopulations are quite similar. The kinematics are compared to the planetary nebula population where differences are apparent in the outer regions of the halo. The total mass of NGC 5128 is found using the Tracer Mass estimator (Evans et al. 2003), to determine the mass supported by internal random motions, and the spherical component of the Jeans equation to determine the mass supported by rotation. We find a total mass of (1.0+/-0.2) x 10^(12) Msun from the planetary nebulae data out to a projected radius of 90 kpc and (1.3+/-0.5) x 10^(12) Msun from the globular clusters out to a projected radius of 50 kpc. Lastly, we present a new and homogeneous catalog of known globular clusters in NGC 5128. This catalog combines all previous definitive cluster identifications from radial velocity studies and HST imaging studies, as well as 80 new globular clusters from a study of M.A. Beasley et al. (2007, in preparation).

Kristin A. Woodley; William E. Harris; Michael A. Beasley; Eric W. Peng; Terry J. Bridges; Duncan A. Forbes; Gretchen L. H. Harris

2007-04-10T23:59:59.000Z

173

Rain sampling device  

DOE Patents [OSTI]

The present invention constitutes a rain sampling device adapted for independent operation at locations remote from the user which allows rainfall to be sampled in accordance with any schedule desired by the user. The rain sampling device includes a mechanism for directing wet precipitation into a chamber, a chamber for temporarily holding the precipitation during the process of collection, a valve mechanism for controllably releasing samples of the precipitation from the chamber, a means for distributing the samples released from the holding chamber into vessels adapted for permanently retaining these samples, and an electrical mechanism for regulating the operation of the device. 11 figures.

Nelson, D.A.; Tomich, S.D.; Glover, D.W.; Allen, E.V.; Hales, J.M.; Dana, M.T.

1991-05-14T23:59:59.000Z

174

Rain sampling device  

DOE Patents [OSTI]

The present invention constitutes a rain sampling device adapted for independent operation at locations remote from the user which allows rainfall to be sampled in accordance with any schedule desired by the user. The rain sampling device includes a mechanism for directing wet precipitation into a chamber, a chamber for temporarily holding the precipitation during the process of collection, a valve mechanism for controllably releasing samples of said precipitation from said chamber, a means for distributing the samples released from the holding chamber into vessels adapted for permanently retaining these samples, and an electrical mechanism for regulating the operation of the device.

Nelson, Danny A. (Richland, WA); Tomich, Stanley D. (Richland, WA); Glover, Donald W. (Prosser, WA); Allen, Errol V. (Benton City, WA); Hales, Jeremy M. (Kennewick, WA); Dana, Marshall T. (Richland, WA)

1991-01-01T23:59:59.000Z

175

Pair extended coupled cluster doubles  

E-Print Network [OSTI]

The accurate and efficient description of strongly correlated systems remains an important challenge for computational methods. Doubly occupied configuration interaction (DOCI), in which all electrons are paired and no correlations which break these pairs are permitted, can in many cases provide an accurate account of strong correlations, albeit at combinatorial computational cost. Recently, there has been significant interest in a method we refer to as pair coupled cluster doubles (pCCD), a variant of coupled cluster doubles in which the electrons are paired. This is simply because pCCD provides energies nearly identical to those of DOCI, but at mean-field computational cost (disregarding the cost of the two-electron integral transformation). Here, we introduce the more complete pair extended coupled cluster doubles (pECCD) approach which, like pCCD, has mean-field cost and reproduces DOCI energetically. We show that unlike pCCD, pECCD also reproduces the DOCI wave function with high accuracy. Moreoever, pEC...

Henderson, Thomas M; Scuseria, Gustavo E

2015-01-01T23:59:59.000Z

176

COMPUTER SCIENCE SAMPLE PROGRAM  

E-Print Network [OSTI]

COMPUTER SCIENCE SAMPLE PROGRAM (First Math Course MATH 198) This sample program suggests one way CS 181: Foundations of Computer Science II CS 180: Foundations of Computer Science I CS 191

Gering, Jon C.

177

Constraining white-dwarf kicks in globular clusters : III. Cluster Heating  

E-Print Network [OSTI]

Recent observations of white dwarfs in globular clusters indicate that these stars may get a velocity kick during their time as giants. This velocity kick could originate naturally if the mass loss while on the asymptotic giant branch is slightly asymmetric. The kicks may be large enough to dramatically change the radial distribution of young white dwarfs, giving them larger energies than other stars in the cluster. As these energetic white dwarfs travel through the cluster they can impart their excess energy on the other stars in the cluster. This new heat source for globular clusters is expected to be largest during the clusters' youth.

Jeremy S. Heyl

2009-03-31T23:59:59.000Z

178

DEXA'11, Toulouse, France, 31.08.2011 Sampling National Deep Web  

E-Print Network [OSTI]

DEXA'11, Toulouse, France, 31.08.2011 Sampling National Deep Web Denis Shestakov, fname-IP cluster random sampling Results Conclusions #12;Background Deep Web: web content behind search, the science and practice of deep web crawling is in its infancy" (in 'Web crawling', Olston&Najork, 2010) #12

Hammerton, James

179

The Architecture of Ant-Based Clustering to improve Topographic Mapping  

E-Print Network [OSTI]

behind ant-based clustering is that autonomous stochastic agents, called ants, move data objects on a low stochastic agents, called ants, that move input samples x X from m(x) to new location m (x). #12;Ants might. Probabilities for picking and dropping are computed using the average similarity x(i) between x X and input sam

180

Cosmological constraints from the virial mass function of nearby galaxy groups and clusters  

E-Print Network [OSTI]

In this thesis, I present a new determination of the cluster mass function in a volume ~107 h-03 70 Mpc3 using the ROSAT-2MASS-FAST Group Survey (R2FGS). R2FGS is an X-ray-selected sample of systems from the ROSAT All-Sky ...

Hill, James Colin

2008-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "four-stage cluster sampling" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

Host-IP Clustering Technique for Deep Web Characterization Denis Shestakov  

E-Print Network [OSTI]

Host-IP Clustering Technique for Deep Web Characterization Denis Shestakov Department of Media databases. This part of the Web, known as the deep Web, is to date relatively unexplored and even major are aimed at more accurate estimation of main parameters of the deep Web by sampling one national web domain

Hammerton, James

182

Reactive cluster model of metallic glasses  

SciTech Connect (OSTI)

Though discovered more than a half century ago metallic glasses remain a scientific enigma. Unlike crystalline metals, characterized by short, medium, and long-range order, in metallic glasses short and medium-range order persist, though long-range order is absent. This fact has prompted research to develop structural descriptions of metallic glasses. Among these are cluster-based models that attribute amorphous structure to the existence of clusters that are incommensurate with crystalline periodicity. Not addressed, however, are the chemical factors stabilizing these clusters and promoting their interconnections. We have found that glass formers are characterized by a rich cluster chemistry that above the glass transformation temperature promotes exchange as well as static and vibronic sharing of atoms between clusters. The vibronic mechanism induces correlated motions between neighboring clusters and we hypothesize that the distance over which these motions are correlated mediates metallic glass stability and influences critical cooling rates.

Jones, Travis E. [Molecular Theory Group, Colorado School of Mines, Golden, Colorado 80401 (United States) [Molecular Theory Group, Colorado School of Mines, Golden, Colorado 80401 (United States); School of Physics, The University of Sydney, Sydney, New South Wales 2006 (Australia); Miorelli, Jonathan; Eberhart, Mark E. [Molecular Theory Group, Colorado School of Mines, Golden, Colorado 80401 (United States)] [Molecular Theory Group, Colorado School of Mines, Golden, Colorado 80401 (United States)

2014-02-28T23:59:59.000Z

183

X-ray spectroscopy of manganese clusters  

SciTech Connect (OSTI)

Much of this thesis represents the groundwork necessary in order to probe Mn clusters more productively than with conventional Mn K-edge XAS and is presented in Part 1. Part 2 contains the application of x-ray techniques to Mn metalloproteins and includes a prognosis at the end of each chapter. Individual Mn oxidation states are more readily distinguishable in Mn L-edge spectra. An empirical mixed valence simulation routine for determining the average Mn oxidation state has been developed. The first Mn L-edge spectra of a metalloprotein were measured and interpreted. The energy of Mn K{beta} emission is strongly correlated with average Mn oxidation state. K{beta} results support oxidation states of Mn(III){sub 2}(IV){sub 2} for the S{sub 1} state of Photosystem II chemical chemically reduced preparations contain predominantly Mn(II). A strength and limitation of XAS is that it probes all of the species of a particular element in a sample. It would often be advantageous to selectively probe different forms of the same element. The first demonstration that chemical shifts in x-ray fluorescence energies can be used to obtain oxidation state-selective x-ray absorption spectra is presented. Spin-dependent spectra can also be used to obtain a more simplified picture of local structure. The first spin-polarized extended x-ray absorption fine structure using Mn K{beta} fluorescence detection is shown.

Grush, M.M. [Univ. of California, Davis, CA (United States). Dept. of Applied Science; [Lawrence Berkeley National Lab., CA (United States). Energy and Environment Div.

1996-06-01T23:59:59.000Z

184

MASSIVE BLACK HOLES IN CENTRAL CLUSTER GALAXIES  

SciTech Connect (OSTI)

We explore how the co-evolution of massive black holes (MBHs) and galaxies is affected by environmental effects, addressing in particular MBHs hosted in the central cluster galaxies (we will refer to these galaxies in general as ''CCGs''). Recently, the sample of MBHs in CCGs with dynamically measured masses has increased, and it has been suggested that these MBH masses (M{sub BH}) deviate from the expected correlations with velocity dispersion ({sigma}) and mass of the bulge (M{sub bulge}) of the host galaxy: MBHs in CCGs appear to be ''overmassive''. This discrepancy is more pronounced when considering the M{sub BH}-{sigma} relation than the M{sub BH}-M{sub bulge} one. We show that this behavior stems from a combination of two natural factors: (1) CCGs experience more mergers involving spheroidal galaxies and their MBHs and (2) such mergers are preferentially gas poor. We use a combination of analytical and semi-analytical models to investigate the MBH-galaxy co-evolution in different environments and find that the combination of these two factors is in accordance with the trends observed in current data sets.

Volonteri, Marta [Institut d'Astrophysique de Paris, 98bis Bd. Arago, F-75014 Paris (France); Ciotti, Luca [Dipartimento di Fisica e Astronomia, Universita di Bologna, via Ranzani 1, I-40127 Bologna (Italy)

2013-05-01T23:59:59.000Z

185

Sudden Collapse of a Granular Cluster  

E-Print Network [OSTI]

Single clusters in a vibro-fluidized granular gas in N connected compartments become unstable at strong shaking. They are experimentally shown to collapse very abruptly. The observed cluster lifetime (as a function of the driving intensity) is analytically calculated within a flux model, making use of the self-similarity of the process. After collapse, the cluster diffuses out into the uniform distribution in a self-similar way, with an anomalous diffusion exponent 1/3.

Devaraj van der Meer; Ko van der Weele; Detlef Lohse

2002-04-12T23:59:59.000Z

186

Deriving the mass distribution of M87 from globular clusters  

E-Print Network [OSTI]

We describe a maximum-likelihood method for determining the mass distribution in spherical stellar systems from the radial velocities of a population of discrete test particles. The method assumes a parametric form for the mass distribution and a non-parametric two-integral distribution function. We apply the method to a sample of 161 globular clusters in M87. We find that the mass within 32 kpc is $(2.4\\pm0.6)\\times 10^{12} $M${_\\odot}$, and the exponent of the density profile $\\rho\\propto r^{-\\alpha}$ in the range 10-100 kpc is $\\alpha=1.6\\pm0.4$.The energy distribution suggests a few kinematically distinct groups of globular clusters. The anisotropy of the globular-cluster velocity distribution cannot be determined reliably with the present data. Models fitted to an NFW potential yield similar mass estimates but cannot constrain the concentration radius $r_c$ in the range 10-500 kpc.

Xiaoan Wu; Scott Tremaine

2006-01-23T23:59:59.000Z

187

The Mass Profile of the Coma Galaxy Cluster  

E-Print Network [OSTI]

We use a new redshift survey complete to m_R=15.4 within 4.25 deg from the center of the Coma cluster to measure the mass profile of the cluster to r=5.5 Mpc/h. We extend the profile to r=10 Mpc/h with a further sample complete to m_R=15.4 in 42% of the area within a 10 deg radius and to m_{Zw}=15.5 in the remaining area. Galaxies within this region are falling onto the cluster on moderately radial orbits and thus do not satisfy virial equilibrium. Nonetheless, identification of the caustics in redshift space provides an estimate of the gravitational potential at radius r and hence of the system mass, M(<10 Mpc/h)=(1.65+-0.41)10^{15} M_\\odot/h (1-sigma error). Previous mass estimates derived from optical and X-ray observations are limited to r<2.5 Mpc/h. Our mass profile is consistent with these estimates but extends to distances four times as large. Over the entire range, the mass increases with r at the rate expected for a Navarro, Frenk & White (1997) density profile.

M. J. Geller; Antonaldo Diaferio; M. J. Kurtz

1999-03-19T23:59:59.000Z

188

The BMW Deep X-ray Cluster Survey  

E-Print Network [OSTI]

We briefly describe the main features of the Brera Multi-Wavelet (BMW) survey of serendipitous X-ray clusters, based on the still unexploited ROSAT-HRI archival observations. Cluster candidates are selected from the general BMW catalogue of 20,000 sources based exclusively on their X-ray extension. Contrary to common wisdom, a clever selection of the HRI energy channels allows us to significantly reduce the background noise, thus greatly improving the ability to detect low surface-brightness sources as clusters. The resulting sample of ~250 candidates shows a very good sky coverage down to a flux \\~3x10^-14 erg/s/cm^2 ([0.5-2.0] keV band), i.e comparable to existing PSPC-based deep survey, with a particularly interesting area of ~100 sq.deg. around fluxes ~10^-13 erg/s/cm^2, i.e. where highly-luminous, rare systems at z~0.6-1 can be detected. At the same time, the superior angular resolution of the instrument should avoid biases against intrinsically small systems, while easing the identification process (e.g...

Guzzo, L; Campana, S; Covino, S; Dell'Antonio, I P; Lazzati, D; Longhetti, M; Molinari, E; Panzera, M R; Tagliaferri, G

2001-01-01T23:59:59.000Z

189

A Survey of Open Clusters in the u'g'r'i'z' Filter System: III. Results for the Cluster NGC 188  

E-Print Network [OSTI]

We continue our series of papers describing the results of a photometric survey of open star clusters, primarily in the southern hemisphere, taken in the u'g'r'i'z' filter system. The entire observed sample covered more than 100 clusters, but here we present data only on NGC 188, which is one of the oldest open clusters known in the Milky Way. We fit the Padova theoretical isochrones to our data. Assuming a solar metallicity for NGC 188, we find a distance of 1700+/-100 pc, an age of 7.5+/-0.7 Gyr, and a reddening E(B-V) of 0.025+/-0.005. This yields a distance modulus of 11.23+/-0.14.

Fornal, B; Smith, J A; Allam, S S; Rider, C J; Sung, H; Fornal, Bartosz; Tucker, Douglas L.; Allam, Sahar S.; Rider, Cristin J.; Sung, Hwankyung

2006-01-01T23:59:59.000Z

190

Clustering Categories in Support Vector Machines  

E-Print Network [OSTI]

Jun 23, 2014 ... Abstract: Support Vector Machines (SVM) is the state-of-the-art in Supervised Classification. In this paper the Cluster Support Vector Machines ...

Emilio Carrizosa

2014-06-23T23:59:59.000Z

191

The Impact of Rotation on Cluster Dynamics  

E-Print Network [OSTI]

The evolution of rotating, isolated clusters of stars up to core-collapse is investigated with n-body numerical codes. The simulations start off from axisymmetric generalisations of King profiles, with added global angular momentum. In this contribution I report on results obtained for two sets of single-mass cluster simulations. These confirm the more rapid evolution of even mildly-rotating clusters. A model is presented with rotational energy comparable to omega-Centauri's; it reaches core-collapse in less than half the time required for non-rotating model clusters.

Christian Boily

2000-02-23T23:59:59.000Z

192

Multiphoton ionization of large water clusters  

SciTech Connect (OSTI)

Water clusters are multimers of water molecules held together by hydrogen bonds. In the present work, multiphoton ionization in the UV range coupled with time of flight mass spectrometry has been applied to water clusters with up to 160 molecules in order to obtain information on the electronic states of clusters of different sizes up to dimensions that can approximate the bulk phase. The dependence of ion intensities of water clusters and their metastable fragments produced by laser ionization at 355 nm on laser power density indicates a (3+1)-photon resonance-enhanced multiphoton ionization process. It also explains the large increase of ionization efficiency at 355 nm compared to that at 266 nm. Indeed, it was found, by applying both nanosecond and picosecond laser ionization with the two different UV wavelengths, that no water cluster sequences after n = 9 could be observed at 266 nm, whereas water clusters up to m/z 2000 Th in reflectron mode and m/z 3000 Th in linear mode were detected at 355 nm. The agreement between our findings on clusters of water, especially true in the range with n > 10, and reported data for liquid water supports the hypothesis that clusters above a critical dimension can approximate the liquid phase. It should thus be possible to study clusters just above 10 water molecules, for getting information on the bulk phase structure.

Apicella, B., E-mail: apicella@irc.cnr.it [Combustion Research Institute, IRC–C.N.R., P.le Tecchio 80, 80125 Napoli (Italy); Li, X. [Key Laboratory of Power Machinery and Engineering, Ministry of Education, Shanghai Jiao Tong University, Shanghai 200240 (China); Passaro, M. [CNISM and Chemical Engineering, Materials and Industrial Production Department, University of Naples “Federico II,” P.le Tecchio 80, 80125 Napoli (Italy); Spinelli, N. [CNISM and Physics Department, University of Naples “Federico II,” Via Cintia, 80124 Napoli (Italy); Wang, X. [SPIN–C.N.R., Via Cintia, 80124 Napoli (Italy)

2014-05-28T23:59:59.000Z

193

Optimization of synchronization in gradient clustered networks  

E-Print Network [OSTI]

We consider complex clustered networks with a gradient structure, where sizes of the clusters are distributed unevenly. Such networks describe more closely actual networks in biophysical systems and in technological applications than previous models. Theoretical analysis predicts that the network synchronizability can be optimized by the strength of the gradient field but only when the gradient field points from large to small clusters. A remarkable finding is that, if the gradient field is sufficiently strong, synchronizability of the network is mainly determined by the properties of the subnetworks in the two largest clusters. These results are verified by numerical eigenvalue analysis and by direct simulation of synchronization dynamics on coupled-oscillator networks.

Xingang Wang; Liang Huang; Ying-Cheng Lai; Choy Heng Lai

2007-11-23T23:59:59.000Z

194

Wide field imaging of distant clusters  

E-Print Network [OSTI]

Wide field imaging is key to understanding the build-up of distant clusters and their galaxy population. By focusing on the so far unexplored outskirts of clusters, where infalling galaxies first hit the cluster potential and the hot intracluster medium, we can help separate cosmological field galaxy evolution from that driven by environment. I present a selection of recent advancements in this area, with particular emphasis on Hubble Space Telescope wide field imaging, for its superior capability to deliver galaxy morphologies and precise shear maps of distant clusters.

T. Treu

2004-08-05T23:59:59.000Z

195

From clusters to clouds | EMSL  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation ProposedUsing ZirconiaPolicyFeasibilityFieldMinds"OfficeTourFrom clusters to clouds From

196

Structure stability and spectroscopy of metal clusters. Progress report  

SciTech Connect (OSTI)

Theory based on self-consistent field-linear combinations of atomic orbitals-molecular orbital theory was applied to clusters. Four areas were covered: electronic structure, equilibrium geometries, and stability of charged clusters, interaction of metal clusters with H and halogen atoms, thermal stability of isolated clusters, and stability and optical properties of hetero-atomic clusters. (DLC)

Not Available

1993-06-01T23:59:59.000Z

197

The Seven Sisters DANCe. I. Empirical isochrones, Luminosity and Mass Functions of the Pleiades cluster  

E-Print Network [OSTI]

The DANCe survey provides photometric and astrometric (position and proper motion) measurements for approximately 2 millions unique sources in a region encompassing $\\approx$80deg$^{2}$ centered around the Pleiades cluster. We aim at deriving a complete census of the Pleiades, and measure the mass and luminosity function of the cluster. Using the probabilistic selection method described in Sarro+2014, we identify high probability members in the DANCe ($i\\ge$14mag) and Tycho-2 ($V\\lesssim$12mag) catalogues, and study the properties of the cluster over the corresponding luminosity range. We find a total of 2109 high probability members, of which 812 are new, making it the most extensive and complete census of the cluster to date. The luminosity and mass functions of the cluster are computed from the most massive members down to $\\approx$0.025M$_{\\odot}$. The size, sensitivity and quality of the sample result in the most precise luminosity and mass functions observed to date for a cluster. Our census supersedes ...

Bouy, H; Sarro, L M; Barrado, D; Moraux, E; Bouvier, J; Cuillandre, J -C; Berihuete, A; Olivares, J; Beletsky, Y

2015-01-01T23:59:59.000Z

198

Reactions of cobalt clusters with water and ammonia: Implications for cluster structure  

SciTech Connect (OSTI)

Reactions of cobalt clusters in the 6 to 150 atom size range with water and ammonia are used to probe cluster geometrical structure. Clusters saturated with ammonia are found in several isomeric forms in much of this size region, including a structure based on icosahedral packing for clusters having 50 to 120 atoms. The variations with cluster size of the binding energy for a single water molecule provide evidence for icosahedral structure of the bare cobalt clusters in the same size range seen for the ammoniated clusters. However, both probes suggest that in many cases the bare clusters also have multiple isomers. The evidence for icosahedral structure in the bare and ammoniated clusters disappears above [similar to]120 atoms and is clearly not seen at the third icosahedral shell closing at 147 atoms. Comparison with earlier studies of hydrogenated cobalt clusters and with bare and hydrogenated nickel clusters is made. Reasons for the failure to form the closed-shell 147 atom icosahedral cluster are discussed.

Parks, E.K.; Klots, T.D.; Winter, B.J.; Riley, S.J. (Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States))

1993-10-15T23:59:59.000Z

199

KEYWORDS: geospatial clustering, web service, Web GIS, spatial data mining, clustering 1 INTRODUCTION  

E-Print Network [OSTI]

1 KEYWORDS: geospatial clustering, web service, Web GIS, spatial data mining, clustering 1-poor. Unprecedented amounts of spatial data are gathered quickly and easily through various methods, such as sensorsClustering offers an API and follows the OGC standard data format for spatial data exchange. #12;2 connectivity

200

Detecting Climate Change in Multivariate Time Series Data by Novel Clustering and Cluster Tracing Techniques  

E-Print Network [OSTI]

Detecting Climate Change in Multivariate Time Series Data by Novel Clustering and Cluster Tracing Aachen University, Germany {kremer, guennemann, seidl}@cs.rwth-aachen.de Abstract--Climate change can series, and trace the clusters over time. A climate pattern is categorized as a changing pattern

Note: This page contains sample records for the topic "four-stage cluster sampling" from the National Library of EnergyBeta (NLEBeta).
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201

Near-infrared evolution of brightest cluster galaxies in the most X-ray luminous clusters since z=1  

E-Print Network [OSTI]

We investigate the near infrared evolution of brightest cluster galaxies (BCGs) from a sample of rich galaxy clusters since z=1. By employing an X-ray selection of Lx>1e44 erg s-1 we limit environmental effects by selecting BCGs in comparably high density regions. We find a positive relationship between X-ray and near-infrared luminosity for BCGs in clusters with Lx>5e44 erg s-1. Applying a correction for this relation we reduce the scatter in the BCG absolute magnitude by a factor of 30%. The near-infrared J-K colour evolution demonstrates that the stellar population in BCGs has been in place since at least z=2 and that we expect a shorter period of star formation than that predicted by current hierarchical merger models. We also confirm that there is a relationship between `blue' J-K colour and the presence of BCG emission lines associated with star formation in cooling flows.

J. P. Stott; A. C. Edge; G. P. Smith; A. M. Swinbank; H. Ebeling

2007-12-04T23:59:59.000Z

202

A faint galaxy redshift survey behind massive clusters  

SciTech Connect (OSTI)

This thesis is concerned with the gravitational lensing effect by massive galaxy clusters. We have explored a new technique for measuring galaxy masses and for detecting high-z galaxies by their optical colors. A redshift survey has been obtained at the Keck for a magnitude limited sample of objects (I<23) behind three clusters, A1689, A2390, and A2218 within a radius of 0.5M pc. For each cluster we see both a clear trend of increasing flux and redshift towards the center. This behavior is the result of image magnifications, such that at fixed redshift one sees further down the luminosity function. The gradient of this magnification is, unlike measurements of image distortion, sensitive to the mass profile, and found to depart strongly from a pure isothermal halo. We have found that V RI color selection can be used effectively as a discriminant for finding high-z galaxies behind clusters and present five 4.1 < z < 5.1 spectra which are of very high quality due to their high mean magnification of {approximately}20, showing strong, visibly-saturated interstellar metal lines in some cases. We have also investigated the radio ring lens PKS 1830-211, locating the source and multiple images and detected molecular absorption at mm wavelengths. Broad molecular absorption of width 1/40kms is found toward the southwest component only, where surprisingly it does not reach the base of the continuum, which implies incomplete coverage of the SW component by molecular gas, despite the small projected size of the source, less than 1/8h pc at the absorption redshift.

Frye, Brenda

1999-12-01T23:59:59.000Z

203

Sampled data lattice filters  

E-Print Network [OSTI]

SAMPLED DATA LATTICE FILTERS A Thesis by WILLIAM TERRY THRIFT III Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE December 1979 Major Subfect...: Electrical Engineering SAMPLED DATA LATTICE FILTERS A Thesis by WILLIAM TERRY THRIFT III Approved as to style and content by: (Chair an of Committee) (Hea f Department) (Member) (Member) (Member) (Member) December 1979 ABSTRACT Sampled Data...

Thrift, William Terry

1980-01-01T23:59:59.000Z

204

TIME-SERIES PHOTOMETRY OF GLOBULAR CLUSTERS: M62 (NGC 6266), THE MOST RR LYRAE-RICH GLOBULAR CLUSTER IN THE GALAXY?  

SciTech Connect (OSTI)

We present new time-series CCD photometry, in the B and V bands, for the moderately metal-rich ([Fe/H] {approx_equal} -1.3) Galactic globular cluster M62 (NGC 6266). The present data set is the largest obtained so far for this cluster and consists of 168 images per filter, obtained with the Warsaw 1.3 m telescope at the Las Campanas Observatory and the 1.3 m telescope of the Cerro Tololo Inter-American Observatory, in two separate runs over the time span of 3 months. The procedure adopted to detect the variable stars was the optimal image subtraction method (ISIS v2.2), as implemented by Alard. The photometry was performed using both ISIS and Stetson's DAOPHOT/ALLFRAME package. We have identified 245 variable stars in the cluster fields that have been analyzed so far, of which 179 are new discoveries. Of these variables, 133 are fundamental mode RR Lyrae stars (RRab), 76 are first overtone (RRc) pulsators, 4 are type II Cepheids, 25 are long-period variables (LPVs), 1 is an eclipsing binary, and 6 are not yet well classified. Such a large number of RR Lyrae stars places M62 among the top two most RR Lyrae-rich (in the sense of total number of RR Lyrae stars present) globular clusters known in the Galaxy, second only to M3 (NGC 5272) with a total of 230 known RR Lyrae stars. Since this study covers most but not all of the cluster area, it is not unlikely that M62 is in fact the most RR Lyrae-rich globular cluster in the Galaxy. In like vein, thanks to the time coverage of our data sets, we were also able to detect the largest sample of LPVs known so far in a Galactic globular cluster. We analyze a variety of Oosterhoff type indicators for the cluster, including mean periods, period distribution, Bailey diagrams, and Fourier decomposition parameters (as well as the physical parameters derived therefrom). All of these indicators clearly show that M62 is an Oosterhoff type I system. This is in good agreement with the moderately high metallicity of the cluster, in spite of its predominantly blue horizontal branch morphology-which is more typical of Oosterhoff type II systems. We thus conclude that metallicity plays a key role in defining Oosterhoff type. Finally, based on an application of the 'A-method', we conclude that the cluster RR Lyrae stars have a similar He abundance as M3, although more work on the temperatures of the M62 RR Lyrae is needed before this result can be conclusively established.

Contreras, R. [INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, 40127, Bologna (Italy); Catelan, M. [Departamento de AstronomIa y Astrofisica, Pontificia Universidad Catolica de Chile, Av. Vicuna Mackenna 4860, 782-0436 Macul, Santiago (Chile); Smith, H. A.; Kuehn, C. A. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Pritzl, B. J. [Department of Physics and Astronomy, University of Wisconsin, Oshkosh, WI 54901 (United States); Borissova, J. [Departamento de Fisica y AstronomIa, Facultad de Ciencias, Universidad de ValparaIso, Ave. Gran Bretana 1111, Playa Ancha, Casilla 5030, ValparaIso (Chile)

2010-12-15T23:59:59.000Z

205

uvby-Hbeta CCD photometry and membership segregation of the open cluster NGC 2548; Gaps in the Main Sequence of open clusters  

E-Print Network [OSTI]

Deep CCD photometry in the uvby-Hbeta intermediate-band system is presented for the cluster NGC 2548 (M 48). A complete membership analysis based on astrometric and photometric criteria is applied. The photometric analysis of a selected sample of stars yields a reddening value of E(b-y)=0.06\\pm0.03, a distance modulus of V_0-M_V=9.3\\pm0.5 (725 pc) and a metallicity of [Fe/H]= -0.24\\pm0.27. Through isochrone fitting we find an age of log t = 8.6\\pm0.1 (400 Myr). Our optical photometry and JHK from 2MASS are combined to derive effective temperatures of cluster member stars. The effective temperature distribution along the main sequence of the cluster shows several gaps. A test to study the significance of these gaps in the main sequence of the HR diagram has been applied. The method is also applied to several other open clusters (Pleiades, Hyades, NGC 1817 and M 67) to construct a sequence of metallicities and ages. The comparison of the results of each cluster gives four gaps with high significance (one of the...

Balaguer-Nuńez, L; Galadi-Enriquez, D

2004-01-01T23:59:59.000Z

206

Fermi-LAT constraints on dark matter annihilation cross section from observations of the Fornax cluster  

SciTech Connect (OSTI)

We analyze 2.8-yr data of 1–100 GeV photons for clusters of galaxies, collected with the Large Area Telescope onboard the Fermi satellite. By analyzing 49 nearby massive clusters located at high Galactic latitudes, we find no excess gamma-ray emission towards directions of the galaxy clusters. Using flux upper limits, we show that the Fornax cluster provides the most stringent constraints on the dark matter annihilation cross section. Stacking a large sample of nearby clusters does not help improve the limit for most dark matter models. This suggests that a detailed modeling of the Fornax cluster is important for setting robust limits on the dark matter annihilation cross section based on clusters. We therefore perform the detailed mass modeling and predict the expected dark matter annihilation signals from the Fornax cluster, by taking into account effects of dark matter contraction and substructures. By modeling the mass distribution of baryons (stars and gas) around a central bright elliptical galaxy, NGC 1399, and using a modified contraction model motivated by numerical simulations, we show that the dark matter contraction boosts the annihilation signatures by a factor of 4. For dark matter masses around 10 GeV, the upper limit obtained on the annihilation cross section times relative velocity is (??)?<(2–3) × 10{sup ?25} cm{sup 3} s{sup ?1}, which is within a factor of 10 from the value required to explain the dark matter relic density. This effect is more robust than the annihilation boost due to substructure, and it is more important unless the mass of the smallest subhalos is much smaller than that of the Sun.

Ando, Shin'ichiro [Institute for Theoretical Physics, University of Amsterdam, 1090 GL Amsterdam (Netherlands); Nagai, Daisuke, E-mail: s.ando@uva.nl, E-mail: daisuke.nagai@yale.edu [Department of Physics, Yale University, New Haven, CT 06520 (United States)

2012-07-01T23:59:59.000Z

207

Evolution of the Blue Luminosity-to-Baryon Mass Ratio of Clusters of Galaxies  

E-Print Network [OSTI]

We derive the ratio of total blue luminosity to total baryon mass, LB/Mb, for massive (Mgas at the Abell radius is \\ge 1 \\times 10^{13} h^{-2.5} \\Msolar) clusters of galaxies up to z \\simeq 1 from the literature. Twenty-two clusters in our sample are at z > 0.1. Assuming that the relative mix of hot gas and galaxies in clusters does not change during cluster evolution, we use LB/Mb to probe the star formation history of the galaxy population as a whole in clusters. We find that LB/Mb of clusters increases with redshift from LB/Mb=0.024 (solar units) at z = 0 to \\simeq 0.06 at z=1, indicating a factor of 2-3 brightening (we assume H0=70 km/s/Mpc). This amount of brightening is almost identical to the brightening of the M/LB ratio of early-type galaxies in clusters at 0.02 \\le z \\le 0.83 reported by van Dokkum et al. (1998). We compare the observed brightening of LB/Mb with luminosity evolution models for the galaxy population as a whole, changing the e-folding time of star formation \\tau by 0.1 \\le \\tau \\le 5 Gyr and the formation redshift \\zF by 2 \\le \\zF < \\infty. We find that \\tau=0.1 Gyr 'single burst' models with \\zF \\ge 3 and \\tau=5 Gyr 'disk' models with arbitrary \\zF are consistent with the observed brightening, while models with \\tau=1-2 Gyr tend to predict too steep brightening. We also derive the ratio of blue luminosity density to baryon density for field galaxies, adopting \\Omega_b h^2 = 0.02, and find that blue luminosity per unit baryon is similar in clusters and in fields up to z \\simeq 1 within the observational uncertainties.

Kazuhiro Shimasaku

2000-01-31T23:59:59.000Z

208

THE DENSITY PROFILES OF MASSIVE, RELAXED GALAXY CLUSTERS. II. SEPARATING LUMINOUS AND DARK MATTER IN CLUSTER CORES  

SciTech Connect (OSTI)

We present stellar and dark matter (DM) density profiles for a sample of seven massive, relaxed galaxy clusters derived from strong and weak gravitational lensing and resolved stellar kinematic observations within the centrally located brightest cluster galaxies (BCGs). In Paper I of the series, we demonstrated that the total density profile derived from these data, which span three decades in radius, is consistent with numerical DM-only simulations at radii {approx}> 5-10 kpc, despite the significant contribution of stellar material in the core. Here, we decompose the inner mass profiles of these clusters into stellar and dark components. Parameterizing the DM density profile as a power law {rho}{sub DM}{proportional_to}r {sup -{beta}} on small scales, we find a mean slope ({beta}) = 0.50 {+-} 0.10(random){sup +0.14} {sub -0.13}(systematic). Alternatively, cored Navarro-Frenk-White (NFW) profiles with (log r {sub core}/kpc) = 1.14 {+-} 0.13{sup +0.14} {sub -0.22} provide an equally good description. These density profiles are significantly shallower than canonical NFW models at radii {approx}< 30 kpc, comparable to the effective radii of the BCGs. The inner DM profile is correlated with the distribution of stars in the BCG, suggesting a connection between the inner halo and the assembly of stars in the central galaxy. The stellar mass-to-light ratio inferred from lensing and stellar dynamics is consistent with that inferred using stellar population synthesis models if a Salpeter initial mass function is adopted. We compare these results to theories describing the interaction between baryons and DM in cluster cores, including adiabatic contraction models and the possible effects of galaxy mergers and active galactic nucleus feedback, and evaluate possible signatures of alternative DM candidates.

Newman, Andrew B.; Ellis, Richard S. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, MS 249-17, Pasadena, CA 91125 (United States)] [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, MS 249-17, Pasadena, CA 91125 (United States); Treu, Tommaso; Sand, David J., E-mail: anewman@astro.caltech.edu [Department of Physics, University of California, Santa Barbara, CA 93106 (United States)

2013-03-01T23:59:59.000Z

209

THE APM CLUSTER SURVEY: CLUSTER DETECTION AND LARGE-SCALE STRUCTURE  

E-Print Network [OSTI]

The APM Cluster Survey was based on a modification of Abell's original classification scheme for galaxy clusters. Here we discuss the results of an investigation of the stability of the statistical properties of the cluster catalogue to changes in the selection parameters. For a poor choice of selection parameters we find clear indications of line-of-sight clusters, but there is a wide range of input parameters for which the statistical properties of the catalogue are stable. We conclude that clusters selected in this way are indeed useful as tracers of large-scale structure.

G. B. Dalton

1995-05-17T23:59:59.000Z

210

Knowledge-based cluster development in India : opportunities and challenges  

E-Print Network [OSTI]

Knowledge-based industries tend to cluster. The nature of activities illustrate the importance of networks and virtual and proximity aspects of clustering. Review of existing literature brings out the advantages of clustering ...

Singla, Chandan Dev

2008-01-01T23:59:59.000Z

211

Dynamics of excess electrons in atomic and molecular clusters  

E-Print Network [OSTI]

Time-Resolved Dynamics in Acetonitrile Cluster Anions (CH 3Time-resolved dynamics in acetonitrile clusters anions (CH 3resolved dynamics in acetonitrile clusters anions (CH 3 CN)

Young, Ryan Michael

2011-01-01T23:59:59.000Z

212

A New Radio - X-Ray Probe of Galaxy Cluster Magnetic Fields  

E-Print Network [OSTI]

Results are presented of a new VLA-ROSAT study that probes the magnetic field strength and distribution over a sample of 16 ``normal'' low redshift (z = 5-10 (l/10 kpc)^{-1/2} microGauss, where l is the field correlation length. These results lead to a global estimate of the total magnetic energy in clusters, and give new insight into the ultimate energy origin, which is likely gravitational. These results also shed some light on the cluster evolutionary conditions that existed at the onset of cooling flows.

T. E. Clarke; P. P. Kronberg; H. Boehringer

2000-11-14T23:59:59.000Z

213

Functional Clustering in Nested Designs Abel Rodriguez  

E-Print Network [OSTI]

Functional Clustering in Nested Designs Abel Rodriguez University of California, Santa Cruz) and oceanography (Rodriguez et al., 2008a). Because functional data are inherently complex, functional clustering the principal points of random functions; James & Sugar (2003), who develop methods for sparsely sam- pled

West, Mike

214

Luminosity function of clusters of galaxies  

E-Print Network [OSTI]

The composite galaxy luminosity function (hereafter LF) of 39 Abell clusters of galaxies is derived by computing the statistical excess of galaxy counts in the cluster direction with respect to control fields. Due to the wide field coverage of the digitised POSS-II plates, we can measure field counts around each cluster in a fully homogeneous way. Furthermore, the availability of virtually unlimited sky coverage allows us to directly compute the LF errors without having to rely on the estimated variance of the background. The wide field coverage also allows us to derive the LF of the whole cluster, including galaxies located in the cluster outskirts. The global composite LF has a slope alpha ~ -1.1+/-0.2 with minor variations from blue to red filters, and M* ~ -21.7,-22.2,-22.4 mag (H_0=50 km/s/Mpc) in g, r and i filters, respectively. These results are in quite good agreement with several previous determinations and in particular with the LF determined for the inner region of a largely overlapping set of clusters, but derived making use of a completely different method for background subtraction. The similarity of the two LFs suggests the existence of minor differences between the LF in the cluster outskirts and in the central region, or a negligible contribution of galaxies in the cluster outskirts to the global LF.

M. Paolillo; S. Andreon; G. Longo; E. Puddu; R. R. Gal; R. Scaramella; S. G. Djorgovski; R. de Carvalho

2000-12-11T23:59:59.000Z

215

STELLAR ENCOUNTER RATE IN GALACTIC GLOBULAR CLUSTERS  

SciTech Connect (OSTI)

The high stellar densities in the cores of globular clusters cause significant stellar interactions. These stellar interactions can produce close binary mass-transferring systems involving compact objects and their progeny, such as X-ray binaries and radio millisecond pulsars. Comparing the numbers of these systems and interaction rates in different clusters drives our understanding of how cluster parameters affect the production of close binaries. In this paper we estimate stellar encounter rates ({Gamma}) for 124 Galactic globular clusters based on observational data as opposed to the methods previously employed, which assumed 'King-model' profiles for all clusters. By deprojecting cluster surface brightness profiles to estimate luminosity density profiles, we treat 'King-model' and 'core-collapsed' clusters in the same way. In addition, we use Monte Carlo simulations to investigate the effects of uncertainties in various observational parameters (distance, reddening, surface brightness) on {Gamma}, producing the first catalog of globular cluster stellar encounter rates with estimated errors. Comparing our results with published observations of likely products of stellar interactions (numbers of X-ray binaries, numbers of radio millisecond pulsars, and {gamma}-ray luminosity) we find both clear correlations and some differences with published results.

Bahramian, Arash; Heinke, Craig O.; Sivakoff, Gregory R.; Gladstone, Jeanette C., E-mail: bahramia@ualberta.ca [Department of Physics, University of Alberta, CCIS 4-183, Edmonton, AB, T5K 1V4 (Canada)

2013-04-01T23:59:59.000Z

216

PHOTOIONIZED TOF MASS SPECTROMETRY OF ATOMIC CLUSTERS  

E-Print Network [OSTI]

for sev eral cluster sou rce nozzle condition s. Heliu m gas pressu re at the tim e of v aporization of solid m aterial played the key role in cluster size range obtain ed. Th e effect of pressu re was thorou

Maruyama, Shigeo

217

Clustering Web Search Results Using Fuzzy Ants  

E-Print Network [OSTI]

Clustering Web Search Results Using Fuzzy Ants Steven Schockaert,* Martine De Cock, Chris Cornelis and Uncertainty Modelling Research Unit, Krijgslaan 281 (S9), B-9000 Gent, Belgium Algorithms for clustering Web existing approaches and illustrates how our algorithm can be applied to the problem of Web search results

Gent, Universiteit

218

Cluster Parallel Loops Part I. Preliminaries  

E-Print Network [OSTI]

;14­2 BIG CPU, BIG DATA he massively parallel Bitcoin mining program in Chapter 13 still doesn't take full advantage of the cluster's parallel processing capabilities. Each Bitcoin mining task uses all the cores on just one node. So on the 10-node tardis cluster, I have to mine 10 or more Bitcoins to fully utilize

Kaminsky, Alan

219

Energy Accounting and Control on HPC clusters  

E-Print Network [OSTI]

Energy Accounting and Control on HPC clusters Yiannis Georgiou R&D Software Engineer #12;Objectives Issues that we wanted to deal with: Measure power and energy consumption on HPC clusters Attribute power and energy data to HPC components Calculate the energy consumption of jobs in the system Extract power

Lefèvre, Laurent

220

Regional Innovation Clusters September 25 , 2012  

E-Print Network [OSTI]

prosperity ­ Find, birth, build and celebrate clusters ­ Improve the business environment ­ Connect the dots by Professor Michael E. Porter and Monitor Company Group, L.P. -- Confidential -- CAM Q BMW Spartanburg #12 Automotive Cluster #12;Timken Technology Center Carroll A. Campbell Graduate Engineering Center IBMOracle BMW

Levinson, David M.

Note: This page contains sample records for the topic "four-stage cluster sampling" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Rehabilitation Services Sample Occupations  

E-Print Network [OSTI]

/Industries Correction Agencies Drug Treatment Centers Addiction Counselor Advocacy Occupations Art Therapist BehavioralRehabilitation Services Sample Occupations Sample Work Settings Child & Day Care Centers Clinics................................ IIB 29-1000 E4 Careers in Counseling and Human Services .........IIB 21-1010 C7 Careers in Health Care

Ronquist, Fredrik

222

Sampling system and method  

DOE Patents [OSTI]

The present disclosure provides an apparatus and method for coupling conduit segments together. A first pump obtains a sample and transmits it through a first conduit to a reservoir accessible by a second pump. The second pump further conducts the sample from the reservoir through a second conduit.

Decker, David L.; Lyles, Brad F.; Purcell, Richard G.; Hershey, Ronald Lee

2013-04-16T23:59:59.000Z

223

IP Profiling via Service Cluster Membership Vectors  

SciTech Connect (OSTI)

This study investigates the feasibility of establishing and maintaining a system of compact IP behavioral profiles as a robust means of computer anomaly definition and detection. These profiles are based upon the degree to which a system's (IP's) network traffic is distributed among stable characteristic clusters derived of the aggregate session traffic generated by each of the major network services. In short, an IP's profile represents its degree of membership in these derived service clusters. The goal is to quantify and rank behaviors that are outside of the statistical norm for the services in question, or present significant deviation from profile for individual client IPs. Herein, we establish stable clusters for accessible features of common session traffic, migrate these clusters over time, define IP behavior profiles with respect to these clusters, migrate individual IP profiles over time, and demonstrate the detection of IP behavioral changes in terms of deviation from profile.

Bartoletti, A

2009-02-23T23:59:59.000Z

224

Bipartite graph partitioning and data clustering  

SciTech Connect (OSTI)

Many data types arising from data mining applications can be modeled as bipartite graphs, examples include terms and documents in a text corpus, customers and purchasing items in market basket analysis and reviewers and movies in a movie recommender system. In this paper, the authors propose a new data clustering method based on partitioning the underlying biopartite graph. The partition is constructed by minimizing a normalized sum of edge weights between unmatched pairs of vertices of the bipartite graph. They show that an approximate solution to the minimization problem can be obtained by computing a partial singular value decomposition (SVD) of the associated edge weight matrix of the bipartite graph. They point out the connection of their clustering algorithm to correspondence analysis used in multivariate analysis. They also briefly discuss the issue of assigning data objects to multiple clusters. In the experimental results, they apply their clustering algorithm to the problem of document clustering to illustrate its effectiveness and efficiency.

Zha, Hongyuan; He, Xiaofeng; Ding, Chris; Gu, Ming; Simon, Horst D.

2001-05-07T23:59:59.000Z

225

Web document clustering using hyperlink structures  

SciTech Connect (OSTI)

With the exponential growth of information on the World Wide Web there is great demand for developing efficient and effective methods for organizing and retrieving the information available. Document clustering plays an important role in information retrieval and taxonomy management for the World Wide Web and remains an interesting and challenging problem in the field of web computing. In this paper we consider document clustering methods exploring textual information hyperlink structure and co-citation relations. In particular we apply the normalized cut clustering method developed in computer vision to the task of hyperdocument clustering. We also explore some theoretical connections of the normalized-cut method to K-means method. We then experiment with normalized-cut method in the context of clustering query result sets for web search engines.

He, Xiaofeng; Zha, Hongyuan; Ding, Chris H.Q; Simon, Horst D.

2001-05-07T23:59:59.000Z

226

On Spectral Clustering: Analysis and an algorithm  

E-Print Network [OSTI]

Despite many empirical successes of spectral clustering methods -- algorithms that cluster points using eigenvectors of matrices derived from the distances between the points -- there are several unresolved issues. First, there is a wide variety of algorithms that use the eigenvectors in slightly different ways. Second, many of these algorithms have no proof that they will actually compute a reasonable clustering. In this paper, we present a simple spectral clustering algorithm that can be implemented using a few lines of Matlab. Using tools from matrix perturbation theory, we analyze the algorithm, and give conditions under which it can be expected to do well. We also show surprisingly good experimental results on a number of challenging clustering problems.

Andrew Y. Ng; Michael I. Jordan; Yair Weiss

2001-01-01T23:59:59.000Z

227

M31 Globular Clusters in the HST Archive: I. Cluster Detection and Completeness  

E-Print Network [OSTI]

Globular clusters at the distance of M31 have apparent angular sizes of a few arcseconds. While many M31 GCs have been detected and studied from ground-based images, the high spatial resolution of HST allows much more robust detection and characterization of star cluster properties. We present the results of a search of 157 HST/WFPC2 images of M31: we found 82 previously-cataloged globular cluster candidates as well as 32 new globular cluster candidates and 20 open cluster candidates. We present images of the new candidates and photometry for all clusters. We assess existing cluster catalogs' completeness and use the results to estimate the total number of GCs in M31 as 460+/-70. The specific frequency is S_N = 1.2+/-0.2 and the mass specific frequency T = 2.4+/-0.4; these values are at the upper end of the range seen for spiral galaxies.

P. Barmby; J. P. Huchra

2001-07-20T23:59:59.000Z

228

Macroeconomic Study of Construction Firm's Profitability Using Cluster Analysis  

E-Print Network [OSTI]

# 2 Cluster # 3 Alabama (AL) Alaska (AK) Arizona (AZ) Arkansas (AR) California (CA) Colorado (CO) Delaware (DE) Connecticut (CT) District of Columbia (DC) Idaho (ID) Hawaii (HI) Florida (FL) Iowa (IA) Illinois (IL) Georgia (GA) Kansas (KS... by Average labor productivity, it can be observed that clusters can be easily discerned as shown in figure 2. 20 Table 2: Clustering Results for Model 2 Cluster # 1 Cluster # 2 Cluster # 3 Alabama (AL) Arkansas (AR) Alaska (AK) Arizona (AZ...

Arora, Parth

2012-10-19T23:59:59.000Z

229

Biological sample collector  

DOE Patents [OSTI]

A biological sample collector is adapted to a collect several biological samples in a plurality of filter wells. A biological sample collector may comprise a manifold plate for mounting a filter plate thereon, the filter plate having a plurality of filter wells therein; a hollow slider for engaging and positioning a tube that slides therethrough; and a slide case within which the hollow slider travels to allow the tube to be aligned with a selected filter well of the plurality of filter wells, wherein when the tube is aligned with the selected filter well, the tube is pushed through the hollow slider and into the selected filter well to sealingly engage the selected filter well and to allow the tube to deposit a biological sample onto a filter in the bottom of the selected filter well. The biological sample collector may be portable.

Murphy, Gloria A. (French Camp, CA)

2010-09-07T23:59:59.000Z

230

THREE-CLUSTER NUCLEAR MOLECULES  

E-Print Network [OSTI]

A three-center phenomenological model able to explain, at least from a qualitative point of view, the difference in the observed yield of a particle-accompanied fission and that of binary fission was developed. It is derived from the liquid drop model under the assumption that the aligned configuration, with the emitted particle between the light and heavy fragment is obtained by increasing continuously the separation distance, while the radii of the light fragment and of the light particle are kept constant. During the first stage of the deformation one has a two-center evolution until the neck radius becomes equal to the radius of the emitted particle. Then the three center starts developing by decreasing with the same amount the two tip distances. In such a way a second minimum, typical for a cluster molecule, appears in the deformation energy. Examples are presented for 240 Pu parent nucleus emitting ?-particles and 14 C in a ternary process. 1

D. N. Poenaru; B. Dobrescu; W. Greiner

2000-01-01T23:59:59.000Z

231

Cryogenic CO2 Formation on Oxidized Gold Clusters Synthesized...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Cryogenic CO2 Formation on Oxidized Gold Clusters Synthesized via Reactive Layer Assisted Deposition. Cryogenic CO2 Formation on Oxidized Gold Clusters Synthesized via Reactive...

232

arom gene cluster: Topics by E-print Network  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

the application of a novel clustering algorithm, Super-Paramagnetic Clustering (SPC) to analysis of gene expression profiles that were generated recently during a study of...

233

almt1 gene cluster: Topics by E-print Network  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

the application of a novel clustering algorithm, Super-Paramagnetic Clustering (SPC) to analysis of gene expression profiles that were generated recently during a study of...

234

Irradiation-induced defect clustering and amorphization in silicon...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Irradiation-induced defect clustering and amorphization in silicon carbide. Irradiation-induced defect clustering and amorphization in silicon carbide. Abstract: Previous computer...

235

High performance computing: Clusters, constellations, MPPs, and future directions  

E-Print Network [OSTI]

and Jim Gray, “High Performance Computing: Crays, Clusters,The Marketplace of High-Performance Computing”, ParallelHigh Performance Computing Clusters, Constellations, MPPs,

Dongarra, Jack; Sterling, Thomas; Simon, Horst; Strohmaier, Erich

2003-01-01T23:59:59.000Z

236

All-Boron Aromatic Clusters as Potential New Inorganic Ligands...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Boron Aromatic Clusters as Potential New Inorganic Ligands and Building Blocks in Chemistry. All-Boron Aromatic Clusters as Potential New Inorganic Ligands and Building Blocks in...

237

Three-dimensional Modeling of Fracture Clusters in Geothermal...  

Broader source: Energy.gov (indexed) [DOE]

Three-dimensional Modeling of Fracture Clusters in Geothermal Reservoirs; 2010 Geothermal Technology Program Peer Review Report Three-dimensional Modeling of Fracture Clusters in...

238

Computer System, Cluster, and Networking Summer Institute Program...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

System, Cluster, and Networking Summer Institute Program Description The Computer System, Cluster, and Networking Summer Institute (CSCNSI) is a focused technical enrichment...

239

Are Cluster Ion Analysis Beams Good Choices for Hydrogen Depth...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Cluster Ion Analysis Beams Good Choices for Hydrogen Depth Profiling Using Time-of-Flight Secondary Ion Mass Spectrometry? Are Cluster Ion Analysis Beams Good Choices for Hydrogen...

240

Optimization of the Coupled Cluster Implementation in NWChem...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

the Coupled Cluster Implementation in NWChem on Petascale Parallel Architectures. Optimization of the Coupled Cluster Implementation in NWChem on Petascale Parallel Architectures....

Note: This page contains sample records for the topic "four-stage cluster sampling" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

2009 Clusters, Nanocrystals & Nanostructures GRC  

SciTech Connect (OSTI)

For over thirty years, this Gordon Conference has been the premiere meeting for the field of cluster science, which studies the phenomena that arise when matter becomes small. During its history, participants have witnessed the discovery and development of many novel materials, including C60, carbon nanotubes, semiconductor and metal nanocrystals, and nanowires. In addition to addressing fundamental scientific questions related to these materials, the meeting has always included a discussion of their potential applications. Consequently, this conference has played a critical role in the birth and growth of nanoscience and engineering. The goal of the 2009 Gordon Conference is to continue the forward-looking tradition of this meeting and discuss the most recent advances in the field of clusters, nanocrystals, and nanostructures. As in past meetings, this will include new topics that broaden the field. In particular, a special emphasis will be placed on nanomaterials related to the efficient use, generation, or conversion of energy. For example, we anticipate presentations related to batteries, catalysts, photovoltaics, and thermoelectrics. In addition, we expect to address the controversy surrounding carrier multiplication with a session in which recent results addressing this phenomenon will be discussed and debated. The atmosphere of the conference, which emphasizes the presentation of unpublished results and lengthy discussion periods, ensures that attendees will enjoy a valuable and stimulating experience. Because only a limited number of participants are allowed to attend this conference, and oversubscription is anticipated, we encourage all interested researchers from academia, industry, and government institutions to apply as early as possible. An invitation is not required. We also encourage all attendees to submit their latest results for presentation at the poster sessions. We anticipate that several posters will be selected for 'hot topic' oral presentations. Because of the important role that students and postdocs play in the future of this field, we also anticipate to select several posters from young investigators for oral presentations.

Lai-Sheng Wang

2009-07-19T23:59:59.000Z

242

Waste classification sampling plan  

SciTech Connect (OSTI)

The purpose of this sampling is to explain the method used to collect and analyze data necessary to verify and/or determine the radionuclide content of the B-Cell decontamination and decommissioning waste stream so that the correct waste classification for the waste stream can be made, and to collect samples for studies of decontamination methods that could be used to remove fixed contamination present on the waste. The scope of this plan is to establish the technical basis for collecting samples and compiling quantitative data on the radioactive constituents present in waste generated during deactivation activities in B-Cell. Sampling and radioisotopic analysis will be performed on the fixed layers of contamination present on structural material and internal surfaces of process piping and tanks. In addition, dose rate measurements on existing waste material will be performed to determine the fraction of dose rate attributable to both removable and fixed contamination. Samples will also be collected to support studies of decontamination methods that are effective in removing the fixed contamination present on the waste. Sampling performed under this plan will meet criteria established in BNF-2596, Data Quality Objectives for the B-Cell Waste Stream Classification Sampling, J. M. Barnett, May 1998.

Landsman, S.D.

1998-05-27T23:59:59.000Z

243

The Group Evolution Multiwavelength Study (GEMS): the Sample and Datasets  

E-Print Network [OSTI]

Galaxy groups have been under-studied relative to their richer counterparts -- clusters. The Group Evolution Multiwavelength Study (GEMS) aims to redress some the balance. Here we describe the GEMS sample selection and resulting sample of 60 nearby (distance dataset of X-ray, optical and HI imaging. ROSAT X-ray images of each group are presented. GEMS also utilizes near-infrared imaging from the 2MASS survey and optical spectra from the 6dFGS. These observational data are complemented by mock group catalogues generated from the latest LCDM simulations with gas physics included. Existing GEMS publications are briefly highlighted as are future publication plans.

Duncan A. Forbes; Trevor Ponman; Frazer Pearce; John Osmond; Virginia Kilborn; Sarah Brough; Somak Raychaudhury; Carole Mundell; Trevor Miles; Katie Kern

2006-02-09T23:59:59.000Z

244

Effects of $?$-cluster breaking on 3$?$ cluster structures in $^{12}$C  

E-Print Network [OSTI]

To clarify the effects of $\\alpha$-cluster breaking on 3$\\alpha$ cluster structures in $^{12}$C, we investigate $^{12}$C using a hybrid model that combines the Brink-Bloch cluster model with the $p_{3/2}$ subshell closure wave function. We have found that $\\alpha$-cluster breaking caused by spin-orbit force significantly changes cluster structures of excited $0^{+}$ states through orthogonality to lower states. Spatially developed cluster components of the $0^{+}_{2}$ state are reduced. The $0^{+}_{3}$ state changes from a vibration mode in the bending motion of three $\\alpha$ clusters to a chain-like 3$\\alpha$ structure having an open triangle configuration. As a result of these structure changes of $0^{+}$ states, the band assignment for the $2^{+}_{2}$ state is changed by the $\\alpha$-cluster breaking effect. Namely, in model calculations without the $\\alpha$-cluster breaking effect, the $0^{+}_{2}$ state is assigned to be the band-head of the $2^{+}_{2}$ state. However, when we incorporate $\\alpha$-cluster breaking caused by the spin-orbit force, the $0^{+}_{3}$ state is regarded as the band-head of the $2^{+}_{2}$ state.

Tadahiro Suhara; Yoshiko Kanada-En'yo

2015-02-17T23:59:59.000Z

245

The 2dF Galaxy Redshift Survey: The dependence of galaxy clustering on luminosity and spectral type  

E-Print Network [OSTI]

We investigate the dependence of galaxy clustering on luminosity and spectral type using the 2dF Galaxy Redshift Survey (2dFGRS). Spectral types are assigned using the principal component analysis of Madgwick et al. We divide the sample into two broad spectral classes: galaxies with strong emission lines (`late-types'), and more quiescent galaxies (`early-types'). We measure the clustering in real space, free from any distortion of the clustering pattern due to peculiar velocities, for a series of volume-limited samples. The projected correlation functions of both spectral types are well described by a power law for transverse separations in the range 2 < (sigma/Mpc/h) < 15, with a marginally steeper slope for early-types than late-types. Both early and late types have approximately the same dependence of clustering strength on luminosity, with the clustering amplitude increasing by a factor of ~2.5 between L* and 4 L*. At all luminosities, however, the correlation function amplitude for the early-types is ~50% higher than that of the late-types. These results support the view that luminosity, and not type, is the dominant factor in determining how the clustering strength of the whole galaxy population varies with luminosity.

P. Norberg; C. M. Baugh; E. Hawkins; S. Maddox; D. Madgwick; O. Lahav; S. Cole; C. S. Frenk; I. Baldry; J. Bland-Hawthorn; T. Bridges; R. Cannon; M. Colless; C. Collins; W. Couch; G. Dalton; S. P. Driver; G. Efstathiou; R. S. Ellis; K. Glazebrook; C. Jackson; I. Lewis; S. Lumsden; J. A. Peacock; B. A. Peterson; W. Sutherland; K. Taylor; the 2dFGRS Team

2002-01-24T23:59:59.000Z

246

The Formation History of Globular Clusters  

E-Print Network [OSTI]

The properties of old globular cluster systems in galaxy halos are used to infer quantitative constraints on aspects of generic star (cluster) formation. First, the spatial distribution of globulars in three large galaxies, together with trends in total cluster population vs. galaxy luminosity for 97 early-type systems plus the halo of the Milky Way, imply that bound stellar clusters formed with a universal efficiency throughout early protogalaxies: by mass, always 0.26% of star-forming gas was converted into globulars rather than halo field stars. That this fraction is so robust in the face of extreme variations in local and global galaxy environment suggests that any parcel of gas needs primarily to exceed a relative density threshold in order to form a bound cluster of stars. Second, it is shown that a strict, empirical scaling of total binding energy with luminosity and Galactocentric position is a defining equation for a fundamental plane of Galactic globular clusters. The characteristics of this plane, which subsumes all other observable correlations between the structural parameters of globulars, provide a small but complete set of facts that must be explained by theories of cluster formation and evolution in the Milky Way. It is suggested that the E_b(L,r_{\\rm gc}) relation specifically resulted from star formation efficiencies having been systematically higher inside more massive protoglobular gas clumps.

Dean E. McLaughlin

2000-02-03T23:59:59.000Z

247

Water Sample Concentrator  

ScienceCinema (OSTI)

Automated portable device that concentrates and packages a sample of suspected contaminated water for safe, efficient transport to a qualified analytical laboratory. This technology will help safeguard against pathogen contamination or chemical and biolog

Idaho National Laboratory

2010-01-08T23:59:59.000Z

248

Dark Matter Searches with Cherenkov Telescopes: Nearby Dwarf Galaxies or Local Galaxy Clusters?  

SciTech Connect (OSTI)

In this paper, we compare dwarf galaxies and galaxy clusters in order to elucidate which object class is the best target for gamma-ray DM searches with imaging atmospheric Cherenkov telescopes (IACTs). We have built a mixed dwarfs+clusters sample containing some of the most promising nearby dwarf galaxies (Draco, Ursa Minor, Wilman 1 and Segue 1) and local galaxy clusters (Perseus, Coma, Ophiuchus, Virgo, Fornax, NGC 5813 and NGC 5846), and then compute their DM annihilation flux profiles by making use of the latest modeling of their DM density profiles. We also include in our calculations the effect of DM substructure. Willman 1 appears as the best candidate in the sample. However, its mass modeling is still rather uncertain, so probably other candidates with less uncertainties and quite similar fluxes, namely Ursa Minor and Segue 1, might be better options. As for galaxy clusters, Virgo represents the one with the highest flux. However, its large spatial extension can be a serious handicap for IACT observations and posterior data analysis. Yet, other local galaxy cluster candidates with more moderate emission regions, such as Perseus, may represent good alternatives. After comparing dwarfs and clusters, we found that the former exhibit annihilation flux profiles that, at the center, are roughly one order of magnitude higher than those of clusters, although galaxy clusters can yield similar, or even higher, integrated fluxes for the whole object once substructure is taken into account. Even when any of these objects are strictly point-like according to the properties of their annihilation signals, we conclude that dwarf galaxies are best suited for observational strategies based on the search of point-like sources, while galaxy clusters represent best targets for analyses that can deal with rather extended emissions. Finally, we study the detection prospects for present and future IACTs in the framework of the constrained minimal supersymmetric standard model. We find that the level of the annihilation flux from these targets is below the sensitivities of current IACTs and the future CTA.

Sanchez-Conde, Miguel A.; /KIPAC, Menlo Park /SLAC /IAC, La Laguna /Laguna U., Tenerife; Cannoni, Mirco; /Huelva U.; Zandanel, Fabio; /IAA, Granada; Gomez, Mario E.; /Huelva U.; Prada, Francisco; /IAA, Granada

2012-06-06T23:59:59.000Z

249

Dissolution actuated sample container  

DOE Patents [OSTI]

A sample collection vial and process of using a vial is provided. The sample collection vial has an opening secured by a dissolvable plug. When dissolved, liquids may enter into the interior of the collection vial passing along one or more edges of a dissolvable blocking member. As the blocking member is dissolved, a spring actuated closure is directed towards the opening of the vial which, when engaged, secures the vial contents against loss or contamination.

Nance, Thomas A.; McCoy, Frank T.

2013-03-26T23:59:59.000Z

250

SAMPLING AND ANALYSIS PROTOCOLS  

SciTech Connect (OSTI)

Radiological sampling and analyses are performed to collect data for a variety of specific reasons covering a wide range of projects. These activities include: Effluent monitoring; Environmental surveillance; Emergency response; Routine ambient monitoring; Background assessments; Nuclear license termination; Remediation; Deactivation and decommissioning (D&D); and Waste management. In this chapter, effluent monitoring and environmental surveillance programs at nuclear operating facilities and radiological sampling and analysis plans for remediation and D&D activities will be discussed.

Jannik, T; P Fledderman, P

2007-02-09T23:59:59.000Z

251

The 2dF Galaxy Redshift Survey: correlation with the ROSAT-ESO Flux Limited X-ray (REFLEX) galaxy cluster survey  

E-Print Network [OSTI]

The ROSAT-ESO Flux Limited X-ray (REFLEX) galaxy cluster survey and the 2dF Galaxy Redshift Survey (2dFGRS) respectively comprise the largest, homogeneous X-ray selected cluster catalogue and completed galaxy redshift survey. In this work we combine these two outstanding datasets in order to study the effect of the large-scale cluster environment, as traced by X-ray luminosity, on the properties of the cluster member galaxies. We measure the LX-sigma relation from the correlated dataset and find it to be consistent with recent results found in the literature. Using a sample of 19 clusters with LX>=0.36*10^44 erg s^-1 in the (0.1-2.4 keV) band, and 49 clusters with lower X-ray luminosity, we find that the fraction of early spectral type (eta<=-1.4), passively-evolving galaxies is significantly higher in the high-LX sample within R200. We extend the investigation to include composite bJ cluster luminosity functions, and find that the characteristic magnitude of the Schechter-function fit to the early-type luminosity function is fainter for the high-LX sample compared to the low-LX sample (Delta M*=0.58+/-0.14). This seems to be driven by a deficit of such galaxies with M_bJ ~ -21. In contrast, we find no significant differences between the luminosity functions of star-forming, late-type galaxies. We believe these results are consistent with a scenario in which the high-LX clusters are more dynamically evolved systems than the low-LX clusters.

Matt Hilton; Chris Collins; Roberto De Propris; Ivan K. Baldry; Carlton M. Baugh; Joss Bland-Hawthorn; Terry Bridges; Russell Cannon; Shaun Cole; Matthew Colless; Warrick J. Couch; Gavin B. Dalton; Simon P. Driver; George Efstathiou; Richard S. Ellis; Carlos S. Frenk; Karl Glazebrook; Carole A. Jackson; Ofer Lahav; Ian Lewis; Stuart Lumsden; Steve J. Maddox; Darren Madgwick; Peder Norberg; John A. Peacock; Bruce A. Peterson; Will Sutherland; Keith Taylor

2005-08-09T23:59:59.000Z

252

A Multi-Wavelength Study of Low Redshift Cluster of Galaxies II. Environmental Impact on Galaxy Growth  

E-Print Network [OSTI]

Galaxy clusters provide powerful laboratories for the study of galaxy evolution, particularly the origin of correlations of morphology and star formation rate (SFR) with density. We construct visible to MIR spectral energy distributions (SEDs) of cluster galaxies and use them to measure stellar masses and SFRs in eight low redshift clusters, which we examine as a function of environment. A partial correlation analysis indicates that SFR depends strongly on R/R200 (>99.9% confidence) and is independent of projected local density at fixed radius. SFR also shows no residual dependence on stellar mass. We therefore conclude that interactions with the intra-cluster medium drive the evolution of SFRs in cluster galaxies. A merged sample of galaxies from the five most complete clusters shows \\propto(R/R200)^(1.3+/-0.7) for galaxies with R/R200<0.4. A decline in the fraction of SFGs toward the cluster center contributes most of this effect, but it is accompanied by a reduction in SFRs among star-forming galaxies (...

Atlee, David W

2012-01-01T23:59:59.000Z

253

Liquid sampling system  

DOE Patents [OSTI]

A conduit extends from a reservoir through a sampling station and back to the reservoir in a closed loop. A jet ejector in the conduit establishes suction for withdrawing liquid from the reservoir. The conduit has a self-healing septum therein upstream of the jet ejector for receiving one end of a double-ended cannula, the other end of which is received in a serum bottle for sample collection. Gas is introduced into the conduit at a gas bleed between the sample collection bottle and the reservoir. The jet ejector evacuates gas from the conduit and the bottle and aspirates a column of liquid from the reservoir at a high rate. When the withdrawn liquid reaches the jet ejector the rate of flow therethrough reduces substantially and the gas bleed increases the pressure in the conduit for driving liquid into the sample bottle, the gas bleed forming a column of gas behind the withdrawn liquid column and interrupting the withdrawal of liquid from the reservoir. In the case of hazardous and toxic liquids, the sample bottle and the jet ejector may be isolated from the reservoir and may be further isolated from a control station containing remote manipulation means for the sample bottle and control valves for the jet ejector and gas bleed. 5 figs.

Larson, L.L.

1984-09-17T23:59:59.000Z

254

Online Spectral Clustering on Network Streams  

E-Print Network [OSTI]

.3.1 First Order Approximation (FOA) Approach . . . . . . . . . . . . . 109 7.3.2 Eigen Perturbation Theory Based Approaches . . . . . . . . . . . . . 111 7.3.2.1 General Eigen Perturbation Theory (GEPT) Approach . . . 111 7.3.2.2 Enhanced Eigen Perturbation... of an evolving graph with two snapshots . . . . . . . . . . . . . 109 7.2 The clustering results of the evolving graph in Figure 7.1 by using SC-FOA . 110 xi 7.3 The clustering results of the evolving graph in Figure 7.1 by using FOA . . . 111 7.4 The clustering...

Jia, Yi

2012-12-31T23:59:59.000Z

255

X-ray Spectroscopy of Cooling Clusters  

E-Print Network [OSTI]

We review the X-ray spectra of the cores of clusters of galaxies. Recent high resolution X-ray spectroscopic observations have demonstrated a severe deficit of emission at the lowest X-ray temperatures as compared to that expected from simple radiative cooling models. The same observations have provided compelling evidence that the gas in the cores is cooling below half the maximum temperature. We review these results, discuss physical models of cooling clusters, and describe the X-ray instrumentation and analysis techniques used to make these observations. We discuss several viable mechanisms designed to cancel or distort the expected process of X-ray cluster cooling.

J. R. Peterson; A. C. Fabian

2005-12-21T23:59:59.000Z

256

The 2dF Galaxy Redshift Survey: Luminosity dependence of galaxy clustering  

E-Print Network [OSTI]

We investigate the dependence of the strength of galaxy clustering on intrinsic luminosity using the Anglo-Australian two degree field galaxy redshift survey (2dFGRS). The 2dFGRS is over an order of magnitude larger than previous redshift surveys used to address this issue. We measure the projected two-point correlation function of galaxies in a series of volume-limited samples. The projected correlation function is free from any distortion of the clustering pattern induced by peculiar motions and is well described by a power-law in pair separation over the range 0.1 < r /h Mpc < 10. The clustering of L* galaxies in real space is well fit by a correlation length r0 = 4.9 +/- 0.3 /h Mpc and power-law slope gamma = 1.71 +/- 0.06. The clustering amplitude increases slowly with absolute magnitude for galaxies fainter than M*, but rises more strongly at higher luminosities. At low luminosities, our results agree with measurements from the SSRS2 by Benoist et al. However, we find a weaker dependence of clustering strength on luminosity at the highest luminosities. The correlation function amplitude increases by a factor of 4.0 between $M_{b_{J}} -5\\log_{10}h = -18$ and -22.5, and the most luminous galaxies are 3.0 times more strongly clustered than L* galaxies. The power-law slope of the correlation function shows remarkably little variation for samples spanning a factor of 20 in luminosity. Our measurements are in very good agreement with the predictions of the hierarchical galaxy formation models of Benson et al.

P. Norberg; C. M. Baugh; E. Hawkins; S. Maddox; J. A. Peacock; S. Cole; C. S. Frenk; J. Bland-Hawthorn; T. Bridges; R. Cannon; M. Colless; C. Collins; W. Couch; G. Dalton; S. P. Driver; G. Efstathiou; R. S. Ellis; K. Glazebrook; C. Jackson; O. Lahav; I. Lewis; S. Lumsden; B. A. Peterson; W. Sutherland; K. Taylor; the 2dFGRS Team

2001-10-19T23:59:59.000Z

257

Molecular-like Ag clusters sensitized near-infrared down-conversion luminescence in oxyfluoride glasses for broadband spectral modification  

SciTech Connect (OSTI)

Molecular-like Ag clusters sized at 1–4 nm have been stabilized in Pb/Cd-free oxyfluoride glasses, showing broadband excitation/emission characteristics and unique wavelength-dependent luminescent performance with a maximal quantum yield of 26.9%. It was experimentally demonstrated that an energy transfer route of Ag clusters ? Tb{sup 3+} ? Yb{sup 3+} occurs in Ag{sup +}/Tb{sup 3+}/Yb{sup 3+} tri-doped sample, wherein Ag clusters act as sensitizers for near-infrared down-conversion spectral modification. Hopefully, the proposed strategy that noble metal clusters being applied for harvesting solar radiation may potentially solve the sticky problems of the narrow excitation bandwidth and the low excitation efficiency in rare earth ions doped down-conversion materials.

Lin, Hang; Chen, Daqin; Yu, Yunlong; Zhang, Rui; Wang, Yuansheng [State Key Lab of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)] [State Key Lab of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)

2013-08-26T23:59:59.000Z

258

Cluster size effects on sintering, CO adsorption, and implantation in Ir/SiO{sub 2}  

SciTech Connect (OSTI)

A series of planar model catalysts have been prepared via deposition of Ir{sub n}{sup +} on thermally grown amorphous SiO{sub 2}/Si(100) and ion scattering spectroscopy was used to probe surface structure as a function of cluster size, impact energy, and surface temperature. Deposition of Ir{sub 2} or Ir{sub 10} at low energies and room temperature results in stable clusters forming one- or two-dimensional single layer islands on the oxide surface. Heating the samples to 750 K leads to agglomeration, forming multilayer structures on the surface. Ir{sub 1} deposited under similar conditions sinters into large clusters at room temperature. Deposition at 110 K at least partially stabilizes the Ir atoms with respect to diffusion and sintering. At higher deposition energies, partial implantation into the surface is observed, but this appears to be insufficient to stabilize the clusters against sintering at elevated temperature. At low temperatures, substrate-mediated adsorption of CO is found to be highly efficient, leading to near saturation coverages of CO bound atop the Ir{sub n} clusters. The CO can be removed by careful He{sup +} sputtering. The deposition/binding behavior of Ir{sub n} on SiO{sub 2} is quite different from Ir{sub n}/TiO{sub 2}(110), for which the clusters bind in three-dimensional morphology, starting at Ir{sub 5}. That system also shows substrate-mediated adsorption of CO, but the CO preferentially binds at the periphery of the clusters rather than on top.

Kaden, W. E.; Kunkel, W. A.; Anderson, Scott L. [Department of Chemistry, University of Utah, 315 S. 1400 E. RM 2020, Salt Lake City, Utah 84112-0850 (United States)

2009-09-21T23:59:59.000Z

259

The Globular Cluster Systems in the Coma Ellipticals. IV: WFPC2 Photometry for Five Giant Ellipticals  

E-Print Network [OSTI]

We analyze photometric data in V and I for the globular cluster (GC) systems in five of the giant ellipticals in the Coma Cluster: NGC 4874, 4881, 4889, 4926, and IC 4051. We find that the GC luminosity functions are quite similar to one another, with a turnover derived from a composite sample of more than 9,000 GCs at V = 27.71 +- 0.07 (M_V = -7.3). Both a simple Gaussian curve and an evolved Schechter function fit the bright half of the GCLF equally well, though the Coma GCLF is broader and has a higher ``cutoff mass'' (M_c ~ 3 x 10^6 M_Sun) than in any of the Virgo giants. These five Coma members exhibit a huge range in GC specific frequency, from a low of S_N = 0.7 for NGC 4881 up to 12 for IC 4051 and NGC 4874. No single formation scenario appears able to account for these differences in otherwise-similar galaxies. The supergiant NGC 4874 has the richest globular cluster system known, probably holding more than 30,000 clusters; its true extent is not yet determined and may extend well out into the Coma potential well. For the three biggest GC systems (NGC 4874, 4889, IC 4051), all three populations are dominated by red, metal-rich clusters. Their metallicity distributions also may all have the normal bimodal form, with the two sequences at the expected mean colors (blue) = 0.98 and (red) = 1.15. However, the color distributions and relative numbers of metal-rich clusters show intriguing counterexamples to a trend established by Peng et al. 2008 (ApJ 681, 197) for the Virgo galaxies. At the very highest-density and most massive regimes represented by the Coma supergiants, formation of metal-rich clusters seems to have been especially favored.

W. E. Harris; J. J. Kavelaars; D. A. Hanes; C. J. Pritchet; W. A. Baum

2008-11-10T23:59:59.000Z

260

The APM cluster-galaxy cross-correlation function : Constraints on Omega and galaxy bias  

E-Print Network [OSTI]

(abridged) We estimate the cluster-galaxy cross-correlation function (Xi_cg), from the APM galaxy and galaxy cluster surveys, both in real space from the inversion of projected statistics and in redshift space using the galaxy and cluster redshift samples. The amplitude of Xi_cg is found to be almost independent of cluster richness. At large separations, r >~5 h^-1 Mpc, Xi_cg has a similar shape to the galaxy-galaxy and cluster-cluster autocorrelation functions. Xi_cg in redshift space can be related to the real space Xi_cg by convolution with an appropriate velocity field model. Here we apply a spherical collapse model, which we have tested against N-body simulations, finding that it provides a surprisingly accurate description of the averaged infall velocity of matter into galaxy clusters. We use this model to estimate beta (Omega^{0.6}/b) and find that it tends to overestimate the true result in simulations by only ~10-30%. Application to the APM results yields beta=0.43 with beta < 0.87 at 95% confidence. We also compare the APM Xi_cg and galaxy autocorrelations to results from popular cosmological models and derive two independent estimates of the galaxy biasing expected as a function of scale. Both low and critical density CDM models require anti-biasing by a factor ~2 on scales r <~ 2 h^-1Mpc and an MDM model is consistent with a constant biasing factor on all scales. We use the velocity fields predicted from the different models to distort the APM real space cross-correlation function. Comparison with the APM redshift space Xi_cg yields an estimate of the value of Omega^0.6 needed in each model. Only the low Omega model is fully consistent with observations, with MDM marginally excluded at the ~2 sigma level.

Rupert Croft; Gavin Dalton; George Efstathiou

1998-01-27T23:59:59.000Z

Note: This page contains sample records for the topic "four-stage cluster sampling" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

A search for ultra-compact dwarf galaxies in the Centaurus galaxy cluster  

E-Print Network [OSTI]

Aim: To extend the investigations of ultra-compact dwarf galaxies (UCDs) beyond the well studied Fornax and Virgo clusters. Methods: We measured spectroscopic redshifts of about 400 compact object candidates with 19.2 < V < 22.4 mag in the central region of the Centaurus galaxy cluster (d=43Mpc), using VIMOS@VLT. The luminosity range of the candidates covers that of bright globular clusters (GCs) and of UCDs in Fornax and Virgo. Results: We confirm the cluster membership of 27 compact objects, covering an absolute magnitude range -12.2 < M_V < -10.9 mag. We do not find counterparts to the two very large and bright UCDs in Fornax and Virgo with M_V=-13.5 mag, possibly due to survey incompleteness. The compact objects' distribution in magnitude and space is consistent with that of the GC population. Their kinematics and spatial distribution associate them to the central galaxies rather than to the overall cluster potential. The compact objects have a mean metallicity consistent with that of the metal-rich globular cluster sub-population. Compact objects with high S/N spectra exhibit solar [alpha/Fe] abundances, consistent with typical dwarf elliptical galaxy values and unlike galactic bulge globular clusters. HST based size estimates for a sub-sample of eight compact objects reveal the existence of one very large object with half-light radius r_h around 30 pc, having M_V=-11.6 mag (~10^7 M_sun). This source shows super-solar [alpha/Fe] abundances. Seven further sources are only marginally larger than typical GCs with r_h in the range 4 to 10 pc. Conclusions: We consider the largest compact object found to be the only bona-fide UCD detected in our study. In order to improve our understanding of UCDs in Centaurus, a significant increase of our survey completeness is necessary.

S. Mieske; M. Hilker; A. Jordan; L. Infante; M. Kissler-Patig

2007-06-19T23:59:59.000Z

262

Evolution of globular cluster systems in elliptical galaxies. I. Log-normal initial mass function  

E-Print Network [OSTI]

We study the evolution of globular cluster systems (GCS) in elliptical galaxies and explore the dependence of their main properties on the mass and the size of the host galaxy.The dependence of the evolution of the GCS mass function (GCMF), of the fraction of surviving clusters and of the ratio of the final to initial mass in clusters on the structure of the host galaxy as well as their variation with the galactocentric distance inside individual host galaxies has been thoroughly investigated.After a survey over a large number of different host galaxies we have restricted our attention to a sample of galaxies with effective masses and radii equal to those observed for dwarf,normal and giant ellipticals. We show that, in spite of large differences in the fraction of surviving clusters, the final mean masses of the GCMF in massive galaxies are very similar to each other with a small galaxy-to-galaxy dispersion;low-mass compact galaxies tend to have smaller values of the final mean mass and a larger galaxy-to-galaxy dispersion. These findings are in agreement with those of recent observational analyses. The fraction of surviving clusters increases with the mass of the host galaxy. We show that a small difference between the initial and the final mean mass and dispersion of the GCMF and the lack of a significant radial dependence of the mean mass inside individual galaxies do not necessarily imply that evolutionary processes have been unimportant in the evolution of the initial population of clusters. For giant galaxies most disruption occurs within the effective radius while for low-mass galaxies a significant disruption of clusters takes place also at larger galactocentric distances. The dependence of the results obtained on the initial mean mass of the GCMF is investigated. (abridged)

E. Vesperini

2000-07-18T23:59:59.000Z

263

Constraining globular cluster formation through studies of young massive clusters - V. ALMA observations of clusters in the Antennae  

E-Print Network [OSTI]

Some formation scenarios that have been put forward to explain multiple populations within Globular Clusters (GCs) require that the young massive cluster have large reservoirs of cold gas within them, which is necessary to form future generations of stars. In this paper we use deep observations taken with Atacama Large Millimeter/sub-millimeter Array (ALMA) to assess the amount of molecular gas within 3 young (50-200 Myr) massive (~10^6 Msun) clusters in the Antennae galaxies. No significant CO(3--2) emission was found associated with any of the three clusters. We place upper limits for the molecular gas within these clusters of ~1x10^5 Msun (or <9 % of the current stellar mass). We briefly review different scenarios that propose multiple episodes of star formation and discuss some of their assumptions and implications. Our results are in tension with the predictions of GC formation scenarios that expect large reservoirs of cool gas within young massive clusters at these ages.

Cabrera-Ziri, I; Longmore, S N; Brogan, C; Hollyhead, K; Larsen, S S; Whitmore, B; Johnson, K; Chandar, R; Henshaw, J D; Davies, B; Hibbard, J E

2015-01-01T23:59:59.000Z

264

The 160 Square Degree ROSAT Survey: the Revised Catalog of 201 Clusters with Spectroscopic Redshifts  

E-Print Network [OSTI]

We present the revised catalog of galaxy clusters detected as extended X-ray sources in the 160 Square Degree ROSAT Survey, including spectroscopic redshifts and X-ray luminosities for 200 of the 201 members. The median redshift is z~0.25 and the median X-ray luminosity is 4.2e+43 erg/s/h50^2 (0.5-2.0 keV). This is the largest high-redshift sample of X-ray selected clusters published to date. There are 73 objects at z>0.3 and 22 objects at z>0.5 drawn from a statistically complete flux-limited survey with a median object flux of 1.4d-13 erg/cm^2/s. We describe the optical follow-up of these clusters with an emphasis on our spectroscopy which has yielded 155 cluster redshifts, 110 of which are presented here for the first time. These measurements combined with 45 from the literature and other sources provide near-complete spectroscopic coverage for our survey. We discuss the final optical identifications for the extended X-ray sources in the survey region and compare our results to similar X-ray cluster search...

Mullis, C R; Quintana, H; Vikhlinin, A; Henry, J P; Gioia, I M; Hornstrup, A; Forman, W; Jones, C

2003-01-01T23:59:59.000Z

265

Variance, Skewness & Kurtosis: results from the APM Cluster Redshift Survey and model predictions  

E-Print Network [OSTI]

We estimate the variance $\\xibar_2$, the skewness $\\xibar_3$ and the kurtosis $\\xibar_4$ in the distribution of density fluctuations in a complete sample from the APM Cluster Redshift Survey with 339 clusters and a mean depth $ \\sim 250\\Mpc$. We are able to measure the statistics of fluctuations in spheres of radius $R \\simeq 5-80 \\Mpc$, with reasonable errorbars. The statistics in the cluster distribution follow the hierarchical pattern $\\xibar_J=S_J~\\xibar_2^{J-1}$ with $S_J$ roughly constant, $S_3 \\simeq 2$ and $S_4 \\sim 8$. We analyse the distribution of clusters taken from N-body simulations of different dark matter models. The results are compared with an alternative method of simulating clusters which uses the truncated Zel'dovich approximation. We argue that this alternative method is not reliable enough for making quantitative predictions of $\\xibar$. The N-body simulation results follow similar hierarchical relations to the observations, with $S_J$ almost unaffected by redshift distortions from peculiar motions. The standard $\\Omega=1$ Cold Dark Matter (CDM) model is inconsistent with either the second, third or fourth order statistics at all scales. However both a hybrid Mixed Dark Matter model and a low density CDM variant agree with the $\\xibar_J$ observations.

Enrique Gaztańaga; Rupert Croft; Gavin Dalton

1995-01-31T23:59:59.000Z

266

Spectral Energy Distributions and Masses of 304 M31 Old Star Clusters  

E-Print Network [OSTI]

This paper presents CCD multicolor photometry for 304 old star clusters in the nearby spiral galaxy M31. Of which photometry of 55 star clusters is first obtained. The observations were carried out as a part of the Beijing--Arizona--Taiwan--Connecticut (BATC) Multicolor Sky Survey from 1995 February to 2008 March, using 15 intermediate-band filters covering 3000--10000 \\AA. Detailed comparisons show that our photometry is in agreement with previous measurements. Based on the ages and metallicities from Caldwell et al. and the photometric measurements here, we estimated the clusters' masses by comparing their multicolor photometry with stellar population synthesis models. The results show that the sample clusters have masses between $\\sim 3\\times10^4 M_\\odot$ and $\\sim 10^7 M_\\odot$ with the peak of $\\sim 4\\times10^5 M_\\odot$. The masses here are in good agreement with those in previous studies. Combined with the masses of young star clusters of M31 from Wang et al., we find that the peak of mass of old cluste...

Ma, Jun; Wu, Zhenyu; Zhang, Tianmeng; Zou, Hu; Nie, Jundan; Zhou, Zhiming; Zhou, Xu; Wu, Jianghua; Du, Cuihua; Yuan, Qirong

2014-01-01T23:59:59.000Z

267

Carbon Fiber Cluster Strategy | ornl.gov  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Carbon Fiber Cluster Strategy ORNL has a 40-year history in R&D on fiber-reinforced composite materials, and has been leading DOE's low-cost carbon fiber initiative for more than...

268

1 Globular Cluster Systems William E. Harris  

E-Print Network [OSTI]

1 Globular Cluster Systems William E. Harris Department of Physics & Astronomy, McMaster University; 2 W. E. Harris 7. The GCLF is evaluated as a standard candle for distance determination. For giant E

Harris, William E.

269

UCD Candidates in the Hydra Cluster  

E-Print Network [OSTI]

NGC 3311, the giant cD galaxy in the Hydra cluster (A1060), has one of the largest globular cluster systems known. We describe new Gemini GMOS (g',i') photometry of the NGC 3311 field which reveals that the red, metal-rich side of its globular cluster population extends smoothly upward into the mass range associated with the new class of Ultra-Compact Dwarfs (UCDs). We identify 29 UCD candidates with estimated masses > 6x10^6 solar masses and discuss their characteristics. This UCD-like sequence is the most well defined one yet seen, and reinforces current ideas that the high-mass end of the globular cluster sequence merges continuously into the UCD sequence, which connects in turn to the E galaxy structural sequence.

Elizabeth Wehner; William Harris

2007-08-10T23:59:59.000Z

270

NGC 7789: AN OPEN CLUSTER CASE STUDY  

E-Print Network [OSTI]

We have obtained high-resolution spectra of 32 giants in the open cluster NGC 7789 using the Wisconsin–Indiana–Yale–NOAO Hydra spectrograph. We explore differences in atmospheric parameters and elemental abundances caused ...

Overbeek, Jamie C.

271

The globular cluster system of M31  

E-Print Network [OSTI]

This review presents the current status of our knowledge of M31 star clusters. Given the broadness of the subject, I chose to focus on some of its aspects which are not covered by the other participants in this conference.

P. Jablonka

2001-07-17T23:59:59.000Z

272

Flagship Cluster Hiring Initiative Computational Science  

E-Print Network [OSTI]

Flagship Cluster Hiring Initiative Computational Science: Advancing Research, Society and the Economy Gabrielle Allen (PI) Thomas Sterling (Presenter/co-PI) Department of Computer Science Center for Computation & Technology #12;Computational Science: Advancing Research, Society and the Economy, External

Allen, Gabrielle

273

Gravitational clustering in Static and Expanding Backgrounds  

E-Print Network [OSTI]

A brief summary of several topics in the study of gravitational many body problem is given. The discussion covers both static backgrounds (applicable to astrophysical systems) as well as clustering in an expanding background (relevant for cosmology)

T. Padmanabhan

2003-08-28T23:59:59.000Z

274

Photoelectron Spectroscopy of Cold Hydrated Sulfate Clusters...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

sulfate clusters SO42-(H2O)n (n ) 4-7) at 12 K and ab initio studies to understand the structures and dynamics of these unique solvated systems. A significant increase of...

275

Radial Alignment in Simulated Clusters  

E-Print Network [OSTI]

Observational evidence for the radial alignment of satellites with their dark matter host has been accumulating steadily in the past few years. The effect is seen over a wide range of scales, from massive clusters of galaxies down to galaxy-sized systems, yet the underlying physical mechanism has still not been established. To this end, we have carried out a detailed analysis of the shapes and orientations of dark matter substructures in high-resolution N-body cosmological simulations. We find a strong tendency for radial alignment of the substructure with its host halo: the distribution of halo major axes is very anisotropic, with the majority pointing towards the center of mass of the host. The alignment peaks once the sub-halo has passed the virial radius of the host for the first time, but is not subsequently diluted, even after the halos have gone through as many as four pericentric passages. This evidence points to the existence of a very rapid dynamical mechanism acting on these systems and we argue that tidal torquing throughout their orbits is the most likely candidate.

Maria J. Pereira; Greg L. Bryan; Stuart P. D. Gill

2008-01-23T23:59:59.000Z

276

Smoothed Particle Inference: A Kilo-Parametric Method for X-ray Galaxy Cluster Modeling  

SciTech Connect (OSTI)

We propose an ambitious new method that models the intracluster medium in clusters of galaxies as a set of X-ray emitting smoothed particles of plasma. Each smoothed particle is described by a handful of parameters including temperature, location, size, and elemental abundances. Hundreds to thousands of these particles are used to construct a model cluster of galaxies, with the appropriate complexity estimated from the data quality. This model is then compared iteratively with X-ray data in the form of adaptively binned photon lists via a two-sample likelihood statistic and iterated via Markov Chain Monte Carlo. The complex cluster model is propagated through the X-ray instrument response using direct sampling Monte Carlo methods. Using this approach the method can reproduce many of the features observed in the X-ray emission in a less assumption-dependent way that traditional analyses, and it allows for a more detailed characterization of the density, temperature, and metal abundance structure of clusters. Multi-instrument X-ray analyses and simultaneous X-ray, Sunyaev-Zeldovich (SZ), and lensing analyses are a straight-forward extension of this methodology. Significant challenges still exist in understanding the degeneracy in these models and the statistical noise induced by the complexity of the models.

Peterson, John R.; Marshall, P.J.; /KIPAC, Menlo Park; Andersson, K.; /Stockholm U. /SLAC

2005-08-05T23:59:59.000Z

277

The Clustering of Luminous Red Galaxies in the Sloan Digital Sky Survey Imaging Data  

E-Print Network [OSTI]

We present the 3D real space clustering power spectrum of a sample of \\~600,000 luminous red galaxies (LRGs) measured by the Sloan Digital Sky Survey (SDSS), using photometric redshifts. This sample of galaxies ranges from redshift z=0.2 to 0.6 over 3,528 deg^2 of the sky, probing a volume of 1.5 (Gpc/h)^3, making it the largest volume ever used for galaxy clustering measurements. We measure the angular clustering power spectrum in eight redshift slices and combine these into a high precision 3D real space power spectrum from k=0.005 (h/Mpc) to k=1 (h/Mpc). We detect power on gigaparsec scales, beyond the turnover in the matter power spectrum, on scales significantly larger than those accessible to current spectroscopic redshift surveys. We also find evidence for baryonic oscillations, both in the power spectrum, as well as in fits to the baryon density, at a 2.5 sigma confidence level. The statistical power of these data to constrain cosmology is ~1.7 times better than previous clustering analyses. Varying t...

Padmanabhan, N; Seljak, U; Makarov, A; Bahcall, Neta A; Blanton, M R; Brinkmann, J; Eisenstein, D J; Finkbeiner, D P; Gunn, J E; Hogg, D W; Ivezic, Z; Knapp, G R; Loveday, J; Lupton, R H; Nichol, R C; Schneider, D P; Strauss, M A; Tegmark, M; York, D G

2006-01-01T23:59:59.000Z

278

Fluid sampling system  

DOE Patents [OSTI]

An fluid sampling system allows sampling of radioactive liquid without spillage. A feed tank is connected to a liquid transfer jet powered by a pumping chamber pressurized by compressed air. The liquid is pumped upwardly into a sampling jet of a venturi design having a lumen with an inlet, an outlet, a constricted middle portion, and a port located above the constricted middle portion. The liquid is passed under pressure through the constricted portion causing its velocity to increase and its pressure to be decreased, thereby preventing liquid from escaping. A septum sealing the port can be pierced by a two pointed hollow needle leading into a sample bottle also sealed by a pierceable septum affixed to one end. The bottle is evacuated by flow through the sample jet, cyclic variation in the sampler jet pressure periodically leaves the evacuated bottle with lower pressure than that of the port, thus causing solution to pass into the bottle. The remaining solution in the system is returned to the feed tank via a holding tank. 4 figs.

Houck, E.D.

1994-10-11T23:59:59.000Z

279

Fluid sampling system  

DOE Patents [OSTI]

An fluid sampling system allows sampling of radioactive liquid without spillage. A feed tank is connected to a liquid transfer jet powered by a pumping chamber pressurized by compressed air. The liquid is pumped upwardly into a sampling jet of a venturi design having a lumen with an inlet, an outlet, a constricted middle portion, and a port located above the constricted middle portion. The liquid is passed under pressure through the constricted portion causing its velocity to increase and its pressure to decreased, thereby preventing liquid from escaping. A septum sealing the port can be pierced by a two pointed hollow needle leading into a sample bottle also sealed by a pierceable septum affixed to one end. The bottle is evacuated by flow through the sample jet, cyclic variation in the sampler jet pressure periodically leaves the evacuated bottle with lower pressure than that of the port, thus causing solution to pass into the bottle. The remaining solution in the system is returned to the feed tank via a holding tank.

Houck, Edward D. (Idaho Falls, ID)

1994-01-01T23:59:59.000Z

280

Neutrinos and Gamma Rays from Galaxy Clusters  

E-Print Network [OSTI]

The next generation of neutrino and gamma-ray detectors should provide new insights into the creation and propagation of high-energy protons within galaxy clusters, probing both the particle physics of cosmic rays interacting with the background medium and the mechanisms for high-energy particle production within the cluster. In this paper we examine the possible detection of gamma-rays (via the GLAST satellite) and neutrinos (via the ICECUBE and Auger experiments) from the Coma cluster of galaxies, as well as for the gamma-ray bright clusters Abell 85, 1758, and 1914. These three were selected from their possible association with unidentified EGRET sources, so it is not yet entirely certain that their gamma-rays are indeed produced diffusively within the intracluster medium, as opposed to AGNs. It is not obvious why these inconspicuous Abell-clusters should be the first to be seen in gamma-rays, but a possible reason is that all of them show direct evidence of recent or ongoing mergers. Their identification with the EGRET gamma-ray sources is also supported by the close correlation between their radio and (purported) gamma-ray fluxes. Under favorable conditions (including a proton spectral index of 2.5 in the case of Abell 85, and sim 2.3 for Coma, and Abell 1758 and 1914), we expect ICECUBE to make as many as 0.3 neutrino detections per year from the Coma cluster of galaxies, and as many as a few per year from the Abell clusters 85, 1758, and 1914. Also, Auger may detect as many as 2 events per decade at ~ EeV energies from these gamma-ray bright clusters.

Brandon Wolfe; Fulvio Melia; Roland M. Crocker; Raymond R. Volkas

2008-07-04T23:59:59.000Z

Note: This page contains sample records for the topic "four-stage cluster sampling" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Contribution of White Dwarfs to Cluster Masses  

E-Print Network [OSTI]

I present a literature search through 31 July 1997 of white dwarfs (WDs) in open and globular clusters. There are 36 single WDs and 5 WDs in binaries known among 13 open clusters, and 340 single WDs and 11 WDs in binaries known among 11 globular clusters. From these data I have calculated WD mass fractions for four open clusters (the Pleiades, NGC 2168, NGC 3532, and the Hyades) and one globular cluster (NGC 6121). I develop a simple model of cluster evolution that incorporates stellar evolution but not dynamical evolution to interpret the WD mass fractions. I augment the results of my simple model with N-body simulations incorporating stellar evolution (Terlevich 1987; de la Feunte Marcos 1996; Vesperini & Heggie 1997). I find that even though these clusters undergo moderate to strong kinematical evolution the WD mass fraction is relatively insensitive to kinematical evolution. By comparing the cluster mass functions to that of the Galactic disk, and incorporating plausibility arguments for the mass function of the Galactic halo, I estimate the WD mass fraction in these two populations. I assume the Galactic disk is ~10 Gyrs old (Winget et al. 1987; Liebert, Dahn, & Monet 1988; Oswalt et al. 1996) and that the Galactic halo is ~12 Gyrs old (Reid 1997b; Gratton et al. 1997; Chaboyer et al. 1998), although the WD mass fraction is insensitive to age in this range. I find that the Galactic halo should contain 8 to 9% (alpha = -2.35) or perhaps as much as 15 to 17% (alpha = -2.0) of its stellar mass in the form of WDs. The Galactic disk WD mass fraction should be 6 to 7% (alpha = -2.35), consistent with the empirical estimates of 3 to 7% (Liebert, Dahn, & Monet 1988; Oswalt et al. 1996). (abridged)

Ted von Hippel

1998-02-14T23:59:59.000Z

282

The Efficiency of Globular Cluster Formation  

E-Print Network [OSTI]

(Abridged): The total populations of globular cluster systems (GCSs) are discussed in terms of their connection to the efficiency of globular cluster formation---the mass fraction of star-forming gas that was able to form bound stellar clusters rather than isolated stars or unbound associations---in galaxy halos. Observed variations in GCS specific frequencies (S_N=N_gc/L_gal), both as a function of galactocentric radius in individual systems and globally between entire galaxies, are reviewed in this light. It is argued that trends in S_N do not reflect any real variation in the underlying efficiency of cluster formation; rather, they result from ignoring the hot gas in many large ellipticals. This claim is checked and confirmed in each of M87, M49, and NGC 1399, for which existing data are combined to show that the volume density profile of globular clusters, rho_cl, is directly proportional to the sum of (rho_gas+rho_stars) at large radii. The constant of proportionality is the same in each case: epsilon=0.0026 +/- 0.0005 in the mean. This is identified with the globular cluster formation efficiency. The implication that epsilon might have had a universal value is supported by data on the GCSs of 97 early-type galaxies, on the GCS of the Milky Way, and on the ongoing formation of open clusters. These results have specific implications for some issues in GCS and galaxy formation, and they should serve as a strong constraint on more general theories of star and cluster formation.

Dean E. McLaughlin

1999-01-21T23:59:59.000Z

283

Accelerating semantic graph databases on commodity clusters  

SciTech Connect (OSTI)

We are developing a full software system for accelerating semantic graph databases on commodity cluster that scales to hundreds of nodes while maintaining constant query throughput. Our framework comprises a SPARQL to C++ compiler, a library of parallel graph methods and a custom multithreaded runtime layer, which provides a Partitioned Global Address Space (PGAS) programming model with fork/join parallelism and automatic load balancing over a commodity clusters. We present preliminary results for the compiler and for the runtime.

Morari, Alessandro; Castellana, Vito G.; Haglin, David J.; Feo, John T.; Weaver, Jesse R.; Tumeo, Antonino; Villa, Oreste

2013-10-06T23:59:59.000Z

284

An object-oriented cluster search algorithm  

SciTech Connect (OSTI)

In this work we describe two object-oriented cluster search algorithms, which can be applied to a network of an arbitrary structure. First algorithm calculates all connected clusters, whereas the second one finds a path with the minimal number of connections. We estimate the complexity of the algorithm and infer that the number of operations has linear growth with respect to the size of the network.

Silin, Dmitry; Patzek, Tad

2003-01-24T23:59:59.000Z

285

Nested Cluster Algorithm for Frustrated Quantum Antiferromagnets  

E-Print Network [OSTI]

Simulations of frustrated quantum antiferromagnets suffer from a severe sign problem. We solve the ergodicity problem of the loop-cluster algorithm in a natural way and apply a powerful strategy to address the sign problem. For the spin 1/2 Heisenberg antiferromagnet on a kagome and on a frustrated square lattice, a nested cluster algorithm eliminates the sign problem for large systems. The method is applicable to general lattice geometries but limited to moderate temperatures.

M. Nyfeler; F. -J. Jiang; F. Kämpfer; U. -J. Wiese

2008-03-25T23:59:59.000Z

286

Clustering and Inconsistent Information: A Kernelization Approach  

E-Print Network [OSTI]

CLUSTERING AND INCONSISTENT INFORMATION: A KERNELIZATION APPROACH A Dissertation by YIXIN CAO Submitted to the O ce of Graduate Studies of Texas A&M University in partial ful llment of the requirements for the degree of DOCTOR OF PHILOSOPHY... May 2012 Major Subject: Computer Science CLUSTERING AND INCONSISTENT INFORMATION: A KERNELIZATION APPROACH A Dissertation by YIXIN CAO Submitted to the O ce of Graduate Studies of Texas A&M University in partial ful llment of the requirements...

Cao, Yixin

2012-07-16T23:59:59.000Z

287

DISENTANGLING THE ROLE OF ENVIRONMENTAL PROCESSES IN GALAXY CLUSTERS  

SciTech Connect (OSTI)

In this work, we present the results of a novel approach devoted to disentangling the role of the environmental processes affecting galaxies in clusters. This is based on the analysis of the near-UV (NUV) - r' distributions of a large sample of star-forming galaxies in clusters spanning more than four absolute magnitudes. The galaxies inhabit three distinct environmental regions: virial regions, cluster infall regions, and field environment. We have applied rigorous statistical tests to analyze both the complete NUV - r' distributions and their averages for three different bins of the r'-band galaxy luminosity down to M{sub r{sup '}}{approx}-18, throughout the three environmental regions considered. We have identified the environmental processes that significantly affect the star-forming galaxies in a given luminosity bin by using criteria based on the characteristics of these processes: their typical timescales, the regions where they operate, and the galaxy luminosity range for which their effects are more intense. We have found that the high-luminosity (M{sub r{sup '}}{<=}-20) star-forming galaxies do not show significant signs in their star formation activity of being affected by: (1) the environment in the last {approx}10{sup 8} yr, or (2) a sudden quenching in the last 1.5 Gyr. The intermediate-luminosity (-20< M{sub r{sup '}}{<=}-19) star-forming galaxies appear to be affected by starvation in the virial regions and by the harassment in the virial and infall regions. Low-luminosity (-19

Hernandez-Fernandez, Jonathan D.; Vilchez, J. M.; Iglesias-Paramo, J., E-mail: jonatan@iaa.es [Instituto de Astrofisica de Andalucia, Glorieta de la Astronomia s/n, 18008 Granada (Spain)

2012-05-20T23:59:59.000Z

288

Free floating planets in stellar clusters?  

E-Print Network [OSTI]

We have simulated encounters between planetary systems and single stars in various clustered environments. This allows us to estimate the fraction of systems liberated, the velocity distribution of the liberated planets, and the separation and eccentricity distributions of the surviving bound systems. Our results indicate that, for an initial distribution of orbits that is flat in log space and extends out to 50AU, 50% of the available planets can be liberated in a globular cluster, 25% in an open cluster, and less than 10% in a young cluster. These fractions are reduced to 25%, 12% and 2% if the initial population extends only to 20AU. Furthermore, these free-floating planets can be retained for longer than a crossing time only in a massive globular cluster. It is therefore difficult to see how planets, which by definition form in a disc around a young star, could be subsequently liberated to form a significant population of free floating substellar objects in a cluster.

Kester W. Smith; Ian A. Bonnell

2001-01-05T23:59:59.000Z

289

Feedback from Clustered Sources During Reionization  

E-Print Network [OSTI]

The reionization history of the intergalactic medium (IGM) at high redshift (z > 6) was likely strongly shaped by several global feedback processes. Because the earliest ionizing sources formed at the locations of the rare density peaks, their spatial distribution was strongly clustered. Here we demonstrate that this clustering significantly boosts the impact of feedback processes operating at high redshift. We build a semi-analytical model to include feedback and clustering simultaneously, and apply this model to the suppression of star-formation in minihalos due to photoionization. The model is built on the excursion-set-based formalism of Furlanetto, Zaldarriaga and Hernquist (2004), which incorporates the clustering of ionizing sources, and which we here extend to include suppression of star formation in minihalos. We find that clustering increases the mean HII bubble size by a factor of several, and it dramatically increases the fraction of minihalos that are suppressed, by a factor of up to 60 relative to a randomly distributed population. This enhanced suppression can significantly reduce the electron scattering optical depth, as required by the three-year data from the Wilkinson Microwave Anisotropy Probe (WMAP). We argue that source clustering is likely to similarly boost the importance of a variety of other feedback mechanisms.

Roban Hultman Kramer; Zoltan Haiman; S. Peng Oh

2006-04-10T23:59:59.000Z

290

Viscous sludge sample collector  

DOE Patents [OSTI]

A vertical core sample collection system for viscous sludge. A sample tube's upper end has a flange and is attached to a piston. The tube and piston are located in the upper end of a bore in a housing. The bore's lower end leads outside the housing and has an inwardly extending rim. Compressed gas, from a storage cylinder, is quickly introduced into the bore's upper end to rapidly accelerate the piston and tube down the bore. The lower end of the tube has a high sludge entering velocity to obtain a full-length sludge sample without disturbing strata detail. The tube's downward motion is stopped when its upper end flange impacts against the bore's lower end inwardly extending rim.

Beitel, George A [Richland, WA

1983-01-01T23:59:59.000Z

291

Calcium EXAFS establishes the Mn-Ca cluster in the oxygen-evolving complex of Photosystem II  

SciTech Connect (OSTI)

The proximity of Ca to the Mn cluster of the photosynthetic water-oxidation complex is demonstrated by X-ray absorption spectroscopy. We have collected EXAFS data at the Ca K-edge using active PS II membrane samples that contain approximately 2 Ca per 4 Mn. These samples are much less perturbed than previously investigated Sr-substituted samples, which were prepared subsequent to Ca depletion. The new Ca EXAFS clearly shows backscattering from Mn at 3.4 angstroms, a distance that agrees with that surmised from previously recorded Mn EXAFS. This result is also consistent with earlier related experiments at the Sr K-edge, using samples that contained functional Sr, that show Mn is {approx}; 3.5 angstroms distant from Sr. The totality of the evidence clearly advances the notion that the catalytic center of oxygen evolution is a Mn-Ca heteronuclear cluster.

Cinco, Roehl M.; McFarlane Holman, Karen L.; Robblee, John H.; Yano, Junko; Pizarro, Shelly A.; Bellacchio, Emanuele; Sauer, Kenneth; Yachandra, Vittal K.

2002-08-02T23:59:59.000Z

292

(Electronic structure and reactivities of transition metal clusters)  

SciTech Connect (OSTI)

The following are reported: theoretical calculations (configuration interaction, relativistic effective core potentials, polyatomics, CASSCF); proposed theoretical studies (clusters of Cu, Ag, Au, Ni, Pt, Pd, Rh, Ir, Os, Ru; transition metal cluster ions; transition metal carbide clusters; bimetallic mixed transition metal clusters); reactivity studies on transition metal clusters (reactivity with H{sub 2}, C{sub 2}H{sub 4}, hydrocarbons; NO and CO chemisorption on surfaces). Computer facilities and codes to be used, are described. 192 refs, 13 figs.

Not Available

1992-01-01T23:59:59.000Z

293

Environmental Science: Sample Pathway  

E-Print Network [OSTI]

Environmental Science: Sample Pathway Semester I Semester II Freshman Year CGS Core CGS Core GE 100 Intro to Env Science ES 105 Env Earth Science Sophomore Year CGS Core (CGS NS201 will fulfill CAS BI107 & 124) MA 115 Statistics Summer Environmental Internship Junior Year CH 171 Chem for Health Sciences CH

Goldberg, Bennett

294

THE CONTRIBUTION OF RADIO GALAXY CONTAMINATION TO MEASUREMENTS OF THE SUNYAEV-ZEL'DOVICH DECREMENT IN MASSIVE GALAXY CLUSTERS AT 140 GHz WITH BOLOCAM  

SciTech Connect (OSTI)

We describe in detail our characterization of the compact radio source population in 140 GHz Bolocam observations of a set of 45 massive galaxy clusters. We use a combination of 1.4 and 30 GHz data to select a total of 28 probable cluster-member radio galaxies and also to predict their 140 GHz flux densities. All of these galaxies are steep-spectrum radio sources and they are found preferentially in the cool-core clusters within our sample. In particular, 11 of the 12 brightest cluster-member radio sources are associated with cool-core systems. Although none of the individual galaxies are robustly detected in the Bolocam data, the ensemble-average flux density at 140 GHz is consistent with, but slightly lower than, the extrapolation from lower frequencies assuming a constant spectral index. In addition, our data indicate an intrinsic scatter of {approx_equal} 30% around the power-law extrapolated flux densities at 140 GHz, although our data do not tightly constrain this scatter. For our cluster sample, which is composed of high-mass and moderate-redshift systems, we find that the maximum fractional change in the Sunyaev-Zel'dovich signal integrated over any single cluster due to the presence of these radio sources is {approx_equal} 20%, and only {approx_equal} 1/4 of the clusters show a fractional change of more than 1%. The amount of contamination is strongly dependent on cluster morphology, and nearly all of the clusters with {>=}1% contamination are cool-core systems. This result indicates that radio contamination is not significant compared with current noise levels in 140 GHz images of massive clusters and is in good agreement with the level of radio contamination found in previous results based on lower frequency data or simulations.

Sayers, J.; Mroczkowski, T.; Czakon, N. G.; Golwala, S. R.; Downes, T. P.; Muchovej, S. J. C.; Siegel, S. [Division of Physics, Math, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)] [Division of Physics, Math, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Mantz, A. [Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States)] [Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Ameglio, S.; Pierpaoli, E.; Shitanishi, J. A. [Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089 (United States)] [Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089 (United States); Koch, P. M.; Lin, K.-Y.; Umetsu, K. [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China)] [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China); Molnar, S. M. [LeCosPA Center, National Taiwan University, Taipei 10617, Taiwan (China)] [LeCosPA Center, National Taiwan University, Taipei 10617, Taiwan (China); Moustakas, L., E-mail: jack@caltech.edu [Jet Propulsion Laboratory, Pasadena, CA 91109 (United States)

2013-02-20T23:59:59.000Z

295

Keck Spectroscopy of Globular Clusters in the Virgo Cluster Dwarf Elliptical VCC 1386  

E-Print Network [OSTI]

We present the results of a Keck spectroscopic study of globular clusters associated with the Virgo Cluster dwarf elliptical VCC 1386. We analyze blue spectroscopic absorption lines from 3500-5500 A for 13 globular cluster candidates and confirm that five are associated with VCC 1386. By comparing metal and Balmer line indices of these globular clusters with alpha-enhanced single stellar population models we find that these systems are metal poor with [Fe/H] 5 Gyr at 3 sigma confidence, placing their formation at z >1. This is one of the first spectroscopic studies of globular clusters surrounding dwarfs in a cluster, revealing that some low mass galaxies in rich environments form at least part of their stellar mass early in the history of the universe. We further find that the luminosity weighted stellar population of VCC 1386 itself is younger, and more metal rich than its globular clusters, consistent with (V-I)_0 colors from Hubble Space Telescope imaging. This implies that VCC 1386, like Local Group dEs, has had multiple episodes of star formation. Globular clusters associated with low luminosity systems however appear to be roughly as old as those associated with giant galaxies, contrary to the `downsizing' formation of their bulk stellar populations.

Christopher J. Conselice

2005-11-01T23:59:59.000Z

296

FT-ICR ,,,Carbon Clusters and Metal/Carbon Binary Clusters  

E-Print Network [OSTI]

60 70 80 720 760 800 Ion Mass [amu] ScC60 + C64 + Number of Carbon Atoms Intensity(arb.units) ScC60FT-ICR ,�,æ,éCarbon Clusters and Metal/Carbon Binary Clusters ·>Í­ì·³"¹1 ·C Masamichi Kohno1 , Tetsuya

Maruyama, Shigeo

297

Magnetospheric line radiation event observed simultaneously on board Cluster 1, Cluster 2 and DEMETER spacecraft  

E-Print Network [OSTI]

be related to power line harmonic radiation (PLHR, an electromagnetic radiation from electric power systemsMagnetospheric line radiation event observed simultaneously on board Cluster 1, Cluster 2., O. Santolík, M. Parrot, and J. S. Pickett (2012), Magnetospheric line radiation event observed

Santolik, Ondrej

298

Decoupled Sampling for Graphics Pipelines  

E-Print Network [OSTI]

We propose a generalized approach to decoupling shading from visibility sampling in graphics pipelines, which we call decoupled sampling. Decoupled sampling enables stochastic supersampling of motion and defocus blur at ...

Ragan-Kelley, Jonathan Millar

299

Fluid sampling apparatus and method  

DOE Patents [OSTI]

Incorporation of a bellows in a sampling syringe eliminates ingress of contaminants, permits replication of amounts and compression of multiple sample injections, and enables remote sampling for off-site analysis. 3 figs.

Yeamans, D.R.

1998-02-03T23:59:59.000Z

300

Sample introducing apparatus and sample modules for mass spectrometer  

DOE Patents [OSTI]

An apparatus for introducing gaseous samples from a wide range of environmental matrices into a mass spectrometer for analysis of the samples is described. Several sample preparing modules including a real-time air monitoring module, a soil/liquid purge module, and a thermal desorption module are individually and rapidly attachable to the sample introducing apparatus for supplying gaseous samples to the mass spectrometer. The sample-introducing apparatus uses a capillary column for conveying the gaseous samples into the mass spectrometer and is provided with an open/split interface in communication with the capillary and a sample archiving port through which at least about 90 percent of the gaseous sample in a mixture with an inert gas that was introduced into the sample introducing apparatus is separated from a minor portion of the mixture entering the capillary discharged from the sample introducing apparatus.

Thompson, Cyril V. (Knoxville, TN); Wise, Marcus B. (Kingston, TN)

1993-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "four-stage cluster sampling" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

Sample introducing apparatus and sample modules for mass spectrometer  

DOE Patents [OSTI]

An apparatus for introducing gaseous samples from a wide range of environmental matrices into a mass spectrometer for analysis of the samples is described. Several sample preparing modules including a real-time air monitoring module, a soil/liquid purge module, and a thermal desorption module are individually and rapidly attachable to the sample introducing apparatus for supplying gaseous samples to the mass spectrometer. The sample-introducing apparatus uses a capillary column for conveying the gaseous samples into the mass spectrometer and is provided with an open/split interface in communication with the capillary and a sample archiving port through which at least about 90 percent of the gaseous sample in a mixture with an inert gas that was introduced into the sample introducing apparatus is separated from a minor portion of the mixture entering the capillary discharged from the sample introducing apparatus. 5 figures.

Thompson, C.V.; Wise, M.B.

1993-12-21T23:59:59.000Z

302

Radio Galaxies in Cooling Cores: Insights from a Complete Sample  

E-Print Network [OSTI]

We have observed a new, complete, cooling-core sample with the VLA, in order to understand how the massive black hole in the central galaxy interacts with the local cluster plasma. We find that every cooling core is currently being energized by an active radio jet, which has probably been destabilized by its interaction with the cooling core. We argue that current models of cooling-core radio galaxies need to be improved before they can be used to determine the rate at which the jet is heating the cooling core. We also argue that the extended radio haloes we see in many cooling-core clusters need extended, in situ re-energization, which cannot be supplied solely by the central galaxy.

J. A. Eilek; F. N. Owen

2006-12-04T23:59:59.000Z

303

Near-Infrared Observations of Globular Clusters in NGC 4472, NGC 4594, NGC 3585 and NGC 5813 and Implications for their Ages and Metallicities  

E-Print Network [OSTI]

We present near-infrared photometry of the globular cluster systems of the early-type galaxies NGC 4472, NGC 4594, NGC 3585, and NGC 5813. We combine these near-infrared data, obtained with PANIC at the Magellan Baade 6.5m telescope, with archival optical HST and FORS/VLT data, and use the optical to near-infrared colors to constrain the ages and metallicities of the globular clusters around the target galaxies. For NGC 4472 we have the most extensive near-infrared and optical photometric dataset. These colors show that the NGC 4472 globular cluster system has a broad metallicity distribution and that the clusters are predominantly old (i.e. ages of about 10 Gyr or more). This result agrees well with earlier spectroscopic work on NGC 4472, and is evidence that the combination of optical to near-infrared colors can identify predominantly old systems and distinguish these from systems with a substantial intermediate age component. Based on the smaller sample of combined optical and near-infrared data NGC 4594 and NGC 3585 appear to have predominantly old globular cluster systems, while that of NGC 5813 may have a more significant age spread. We also match our sample of globular clusters with near-infrared and optical photometry to Chandra X-ray source detections in these galaxies, and discuss how the probability that a globular cluster hosts a low-mass X-ray binary depends on metallicity and age.

Maren Hempel; Steve Zepf; Arunav Kundu; Doug Geisler; Thomas J. Maccarone

2007-02-19T23:59:59.000Z

304

Soil sampling kit and a method of sampling therewith  

DOE Patents [OSTI]

A soil sampling device and a sample containment device for containing a soil sample is disclosed. In addition, a method for taking a soil sample using the soil sampling device and soil sample containment device to minimize the loss of any volatile organic compounds contained in the soil sample prior to analysis is disclosed. The soil sampling device comprises two close fitting, longitudinal tubular members of suitable length, the inner tube having the outward end closed. With the inner closed tube withdrawn a selected distance, the outer tube can be inserted into the ground or other similar soft material to withdraw a sample of material for examination. The inner closed end tube controls the volume of the sample taken and also serves to eject the sample. The soil sample containment device has a sealing member which is adapted to attach to an analytical apparatus which analyzes the volatile organic compounds contained in the sample. The soil sampling device in combination with the soil sample containment device allow an operator to obtain a soil sample containing volatile organic compounds and minimizing the loss of the volatile organic compounds prior to analysis of the soil sample for the volatile organic compounds.

Thompson, Cyril V. (Knoxville, TN)

1991-01-01T23:59:59.000Z

305

Soil sampling kit and a method of sampling therewith  

DOE Patents [OSTI]

A soil sampling device and a sample containment device for containing a soil sample is disclosed. In addition, a method for taking a soil sample using the soil sampling device and soil sample containment device to minimize the loss of any volatile organic compounds contained in the soil sample prior to analysis is disclosed. The soil sampling device comprises two close fitting, longitudinal tubular members of suitable length, the inner tube having the outward end closed. With the inner closed tube withdrawn a selected distance, the outer tube can be inserted into the ground or other similar soft material to withdraw a sample of material for examination. The inner closed end tube controls the volume of the sample taken and also serves to eject the sample. The soil sample containment device has a sealing member which is adapted to attach to an analytical apparatus which analyzes the volatile organic compounds contained in the sample. The soil sampling device in combination with the soil sample containment device allows an operator to obtain a soil sample containing volatile organic compounds and minimizing the loss of the volatile organic compounds prior to analysis of the soil sample for the volatile organic compounds. 11 figures.

Thompson, C.V.

1991-02-05T23:59:59.000Z

306

Surface photometry of a sample of elliptical and S0 galaxies  

SciTech Connect (OSTI)

The results are reported of surface photometry of 38 early-type galaxies, located mainly in the Fornax Cluster. Detailed comparisons with previously published work are given along with internal and external error estimates for all quantities, and some serious systematic discrepancies in the older aperture photometry of some of the galaxies in the present sample are pointed out. 15 refs.

De carvalho, R.R.; Da costa, L.N.; Djorgovski, S. (Observatorio Nacional do Brasil, Sao Cristovao (Brazil) California Institute of Technology, Pasadena (United States))

1991-08-01T23:59:59.000Z

307

GALAXY CLUSTER BULK FLOWS AND COLLISION VELOCITIES IN QUMOND  

SciTech Connect (OSTI)

We examine the formation of clusters of galaxies in numerical simulations of a QUMOND cosmogony with massive sterile neutrinos. Clusters formed in these exploratory simulations develop higher velocities than those found in {Lambda}CDM simulations. The bulk motions of clusters attain {approx}1000 km s{sup -1} by low redshift, comparable to observations whereas {Lambda}CDM simulated clusters tend to fall short. Similarly, high pairwise velocities are common in cluster-cluster collisions like the Bullet Cluster. There is also a propensity for the most massive clusters to be larger in QUMOND and to appear earlier than in {Lambda}CDM, potentially providing an explanation for ''pink elephants'' like El Gordo. However, it is not obvious that the cluster mass function can be recovered.

Katz, Harley; McGaugh, Stacy; Teuben, Peter [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Angus, G. W., E-mail: hkatz@astro.umd.edu, E-mail: stacy.mcgaugh@case.edu, E-mail: teuben@astro.umd.edu, E-mail: angus.gz@gmail.com [Astrophysics, Cosmology and Gravity Centre, University of Cape Town, Private Bag X3, Rondebosch 7700 (South Africa)

2013-07-20T23:59:59.000Z

308

Detonation of Meta-stable Clusters  

SciTech Connect (OSTI)

We consider the energy accumulation in meta-stable clusters. This energy can be much larger than the typical chemical bond energy (~;;1 ev/atom). For example, polymeric nitrogen can accumulate 4 ev/atom in the N8 (fcc) structure, while helium can accumulate 9 ev/atom in the excited triplet state He2* . They release their energy by cluster fission: N8 -> 4N2 and He2* -> 2He. We study the locus of states in thermodynamic state space for the detonation of such meta-stable clusters. In particular, the equilibrium isentrope, starting at the Chapman-Jouguet state, and expanding down to 1 atmosphere was calculated with the Cheetah code. Large detonation pressures (3 and 16 Mbar), temperatures (12 and 34 kilo-K) and velocities (20 and 43 km/s) are a consequence of the large heats of detonation (6.6 and 50 kilo-cal/g) for nitrogen and helium clusters respectively. If such meta-stable clusters could be synthesized, they offer the potential for large increases in the energy density of materials.

Kuhl, Allen; Kuhl, Allen L.; Fried, Laurence E.; Howard, W. Michael; Seizew, Michael R.; Bell, John B.; Beckner, Vincent; Grcar, Joseph F.

2008-05-31T23:59:59.000Z

309

Globular Cluster Ages and Stromgren CCD Photometry  

E-Print Network [OSTI]

Stromgren uvby CCD photometry can be used in a variety of ways to constrain the absolute and relative ages of globular clusters. The reddening corrected (v-y, c1) diagram offers the means to derive ages that are completely independent of distance. Very precise differential ages for clusters of the same chemical composition may also be determined from such 2-color plots, or from measurements of the magnitude difference, Delta_u, between the subgiant and horizontal branches on the $u-y, u$ plane (where both of these features are flat and well-defined, even for clusters like M13 that have extremely blue HBs on the (B-V, V) diagram). Based on high-quality photometry we find that: (1) M92 is 15 Gyr old, (2) M3 and M13 differ in age by < 1 Gyr, and (3) NGC 288, NGC 362, and NGC 1851 are coeval to within ~1.5 Gyr. These results strongly suggest that age cannot be the only ``second parameter''. Finally, we suggest that the observed variations in c1 among giant branch stars in all the metal-poor clusters that we have studied so far are likely due to star-to-star C and N abundance variations, and potentially indicate that most (if not all) globular clusters have ``primordial'' variations in at least these elements.

Frank Grundahl

1999-09-23T23:59:59.000Z

310

Confirming EIS Clusters. Multi-object Spectroscopy  

E-Print Network [OSTI]

Using EFOSC2 at the 3.6m ESO telescope, we obtained redshifts for 68 galaxies in the field of six cluster candidates from the ESO Imaging Survey (EIS). The cluster candidates were selected in the EIS patches C and D and have estimated mean redshifts between z=0.5 and z=0.7. In the six candidate cluster fields, we identify possible systems of galaxies in the redshift space. The likelihoods of these systems are established by comparison with random resamplings of the Canada-France Redshift Surveys, and using the redshift distribution expected from Postman et al.'s luminosity function, with Poggianti's K- and evolutionary-corrections. Four of the six candidate EIS clusters are found to correspond to a real system in the redshift space, with > 95 % probability. Two of them have a mean redshift in agreement with the estimate from the matched filter algorithm, while the other two have a significantly smaller redshift. The independent analysis of the V-I vs. I color-magnitude diagrams for five of our six cluster fields, supports our conclusions based on the spectroscopic data.

A. Biviano; M. Ramella; W. Boschin; S. Bardelli; M. Scodeggio; L. N. da Costa; L. F. Olsen; M. Nonino; S. Borgani; M. Girardi

1999-10-26T23:59:59.000Z

311

The Structure of Nuclear Star Clusters in Nearby Late-type Spiral Galaxies from Hubble Space Telescope Wide Field Camera 3 Imaging  

E-Print Network [OSTI]

We obtained Hubble Space Telescope/Wide Field Camera 3 imaging of a sample of ten of the nearest and brightest nuclear clusters residing in late-type spiral galaxies, in seven bands that span the near-ultraviolet to the near-infrared. Structural properties of the clusters were measured by fitting two-dimensional surface brightness profiles to the images using GALFIT. The clusters exhibit a wide range of structural properties. For six of the ten clusters in our sample, we find changes in the effective radius with wavelength, suggesting radially varying stellar populations. In four of the objects, the effective radius increases with wavelength, indicating the presence of a younger population which is more concentrated than the bulk of the stars in the cluster. However, we find a general decrease in effective radius with wavelength in two of the objects in our sample, which may indicate extended, circumnuclear star formation. We also find a general trend of increasing roundness of the clusters at longer waveleng...

Carson, Daniel J; Seth, Anil C; Brok, Mark den; Cappelari, Michele; Greene, Jenny E; Ho, Luis C; Neumayer, Nadine

2015-01-01T23:59:59.000Z

312

Fractal Dimensions of a Weakly Clustered Distribution and the Scale of Homogeneity  

E-Print Network [OSTI]

Homogeneity and isotropy of the universe at sufficiently large scales is a fundamental premise on which modern cosmology is based. Fractal dimensions of matter distribution is a parameter that can be used to test the hypothesis of homogeneity. In this method, galaxies are used as tracers of the distribution of matter and samples derived from various galaxy redshift surveys have been used to determine the scale of homogeneity in the Universe. Ideally, for homogeneity, the distribution should be a mono-fractal with the fractal dimension equal to the ambient dimension. While this ideal definition is true for infinitely large point sets, this may not be realised as in practice, we have only a finite point set. The correct benchmark for realistic data sets is a homogeneous distribution of a finite number of points and this should be used in place of the mathematically defined fractal dimension for infinite number of points (D) as a requirement for approach towards homogeneity. We derive the expected fractal dimension for a homogeneous distribution of a finite number of points. We show that for sufficiently large data sets the expected fractal dimension approaches D in absence of clustering. It is also important to take the weak, but non-zero amplitude of clustering at very large scales into account. In this paper we also compute the expected fractal dimension for a finite point set that is weakly clustered. Clustering introduces departures in the Fractal dimensions from D and in most situations the departures are small if the amplitude of clustering is small. Features in the two point correlation function, like those introduced by Baryon Acoustic Oscillations (BAO) can lead to non-trivial variations in the Fractal dimensions where the amplitude of clustering and deviations from D are no longer related in a monotonic manner.

J. S. Bagla; Jaswant Yadav; T. R. Seshadri

2008-08-04T23:59:59.000Z

313

Sample holder with optical features  

DOE Patents [OSTI]

A sample holder for holding a sample to be observed for research purposes, particularly in a transmission electron microscope (TEM), generally includes an external alignment part for directing a light beam in a predetermined beam direction, a sample holder body in optical communication with the external alignment part and a sample support member disposed at a distal end of the sample holder body opposite the external alignment part for holding a sample to be analyzed. The sample holder body defines an internal conduit for the light beam and the sample support member includes a light beam positioner for directing the light beam between the sample holder body and the sample held by the sample support member.

Milas, Mirko; Zhu, Yimei; Rameau, Jonathan David

2013-07-30T23:59:59.000Z

314

SCALING RELATIONS AND OVERABUNDANCE OF MASSIVE CLUSTERS AT z {approx}> 1 FROM WEAK-LENSING STUDIES WITH THE HUBBLE SPACE TELESCOPE  

SciTech Connect (OSTI)

We present weak gravitational lensing analysis of 22 high-redshift (z {approx}> 1) clusters based on Hubble Space Telescope images. Most clusters in our sample provide significant lensing signals and are well detected in their reconstructed two-dimensional mass maps. Combining the current results and our previous weak-lensing studies of five other high-z clusters, we compare gravitational lensing masses of these clusters with other observables. We revisit the question whether the presence of the most massive clusters in our sample is in tension with the current {Lambda}CDM structure formation paradigm. We find that the lensing masses are tightly correlated with the gas temperatures and establish, for the first time, the lensing mass-temperature relation at z {approx}> 1. For the power-law slope of the M-T{sub X} relation (M{proportional_to}T{sup {alpha}}), we obtain {alpha} = 1.54 {+-} 0.23. This is consistent with the theoretical self-similar prediction {alpha} = 3/2 and with the results previously reported in the literature for much lower redshift samples. However, our normalization is lower than the previous results by 20%-30%, indicating that the normalization in the M-T{sub X} relation might evolve. After correcting for Eddington bias and updating the discovery area with a more conservative choice, we find that the existence of the most massive clusters in our sample still provides a tension with the current {Lambda}CDM model. The combined probability of finding the four most massive clusters in this sample after the marginalization over cosmological parameters is less than 1%.

Jee, M. J.; Lubin, L.; Stanford, S. A. [Department of Physics, University of California, Davis, One Shields Avenue, Davis, CA 95616 (United States); Dawson, K. S.; Harris, D. W. [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Hoekstra, H. [Leiden Observatory, Leiden University, Leiden (Netherlands); Perlmutter, S.; Suzuki, N.; Meyers, J.; Barbary, K. [E.O. Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley CA 94720 (United States); Rosati, P. [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748, Garching (Germany); Brodwin, M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Koester, B.; Gladders, M. D. [Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States); Postman, M. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Barrientos, F. [Department of Astronomy and Astrophysics, Universidad Catolica de Chile, Santiago (Chile); Eisenhardt, P. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Ford, H. C. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Gilbank, D. G. [Department of Physics and Astronomy, University Of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Gonzalez, A. [Department of Astronomy, University of Florida, Gainesville, FL 32611-2055 (United States)

2011-08-20T23:59:59.000Z

315

Time Resolved Photoelectron Imaging of Electronic Relaxation Dynamics in Anionic Clusters  

E-Print Network [OSTI]

Solvation in Iodide-Doped Acetonitrile Clusters, Journal ofSolvation in Iodide-doped Acetonitrile Clusters [ReprintedSolvation in Iodide- doped Acetonitrile Clusters", Oli T.

Griffin, Graham Bailey

2009-01-01T23:59:59.000Z

316

Multi-object spectroscopy of low redshift EIS clusters. I  

E-Print Network [OSTI]

We report the results of the first multi-object spectroscopic observations at the Danish 1.54m telescope at La Silla, Chile. Observations of five cluster candidates from the ESO Imaging Survey Cluster Candidate Catalog are described. From these observations we confirm the reality of the five clusters with measured redshifts of 0.11<=z<=0.35. We estimate velocity dispersions in the range 294-621km/s indicating rather poor clusters. This, and the measured cluster redshifts are consistent with the results of the matched filter procedure applied to produce the Cluster Candidate Catalog.

L. Hansen; L. F. Olsen; H. E. Jorgensen

2002-04-23T23:59:59.000Z

317

CO adsorption on neutral iridium clusters  

E-Print Network [OSTI]

The adsorption of carbon monoxide on neutral iridium clusters in the size range of n = 3 to 21 atoms is investigated with infrared multiple photon dissociation spectroscopy. For each cluster size only a single v(CO) band is present with frequencies in the range between 1962 cm-1 (n = 8) and 1985 cm-1 (n = 18) which can be attributed to an atop binding geometry. This behaviour is compared to the CO binding geometries on clusters of other group 9 and 10 transition metals as well as to that on extended surfaces. The preference of Ir for atop binding is rationalized by relativistic effects on the electronic structure of the later 5d metals.

Kerpal, Christian; Meijer, Gerard; Fielicke, André

2010-01-01T23:59:59.000Z

318

The Broadband Spectrum of Galaxy Clusters  

E-Print Network [OSTI]

We examine whether nonthermal protons energized during a cluster merger are simultaneously responsible for the Coma cluster's diffuse radio flux (via secondary decay) and the departure of its intra-cluster medium (ICM) from a thermal profile via Coulomb collisions between the quasithermal electrons and the hadrons. Rather than approximating the influence of nonthermal proton/thermal electron collisions as extremely rare events which cause an injection of nonthermal, power-law electrons (the `knock-on' approximation), we self-consistently solve (to our knowledge, for the first time) the covariant kinetic equations for the two populations. The electron population resulting from these collisions is out of equilibrium, yet not a power law, and importantly displays a higher bremsstrahlung radiative efficiency than a pure power law. Observations with GLAST will test this model directly.

Brandon Wolfe; Fulvio Melia

2007-12-02T23:59:59.000Z

319

Clustering and Triaxial Deformations of $^{40}$Ca  

E-Print Network [OSTI]

We have studied the positive-parity states of $^{40}$Ca using antisymmetrized molecular dynamics (AMD) and the generator coordinate method (GCM). Imposing two different kinds of constraints on the variational calculation, we have found various kinds of $^{40}{\\rm Ca}$ structures such as a deformed-shell structure, as well as $\\alpha$-$^{36}$Ar and $^{12}$C-$^{28}$Si cluster structures. After the GCM calculation, we obtained a normal-deformed band and a superdeformed band together with their side bands associated with triaxial deformation. The calculated $B(E2)$ values agreed well with empirical data. It was also found that the normal-deformed and superdeformed bands have a non-negligible $\\alpha$-$^{36}$Ar cluster component and $^{12}$C-$^{28}$Si cluster component, respectively. This leads to the presence of an $\\alpha$-$^{36}$Ar higher-nodal band occurring above the normal-deformed band.

Yasutaka Taniguchi; Masaaki Kimura; Yoshiko Kanada-En'yo; Hisashi Horiuchi

2007-07-05T23:59:59.000Z

320

Nonlinear Gravitational Clustering in Expanding Universe  

E-Print Network [OSTI]

The gravitational clustering of collisionless particles in an expanding universe is modelled using some simple physical ideas. I show that it is possible to understand the nonlinear clustering in terms of three well defined regimes: (1) linear regime; (2) quasilinear regime which is dominated by scale-invariant radial infall and (3) nonlinear regime dominated by nonradial motions and mergers. Modelling each of these regimes separately I show how the nonlinear two point correlation function can be related to the linear correlation function in hierarchical models. This analysis leads to results which are in good agreement with numerical simulations thereby providing an explanation for numerical results. Using this model and some simple extensions, it is possible to understand the transfer of power from large to small scales and the behaviour of higher order correlation functions. The ideas presented here will also serve as a powerful analytical tool to investigate nonlinear clustering in different models.

T. Padmanabhan

1996-07-19T23:59:59.000Z

Note: This page contains sample records for the topic "four-stage cluster sampling" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Detecting Eccentric Globular Cluster Binaries with LISA  

E-Print Network [OSTI]

The energy carried in the gravitational wave signal from an eccentric binary is spread across several harmonics of the orbital frequency. The inclusion of the harmonics in the analysis of the gravitational wave signal increases the signal-to-noise ratio of the detected signal for binaries whose fundamental frequency is below the galactic confusion-limited noise cut-off. This can allow for an improved angular resolution for sources whose orbital period is greater than 2000 s. Globular cluster sources include possible binary black holes and neutron stars which may have high eccentricities. Cluster dynamics may also enhance the eccentricities of double white dwarf binaries and white dwarf-neutron star binaries over the galactic sources. Preliminary results of the expected signal-to-noise ratio for selected globular cluster binaries are presented.

M. Benacquista

2001-06-05T23:59:59.000Z

322

E-Print Network 3.0 - aluminum hydrogen cluster Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Collection: Energy Storage, Conversion and Utilization ; Renewable Energy 63 www.praxair.com Copyright 2003, Praxair Technology, Inc. All rights reserved. Summary:...

323

E-Print Network 3.0 - availability cluster system Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

for Moose Michael Meer Summary: extract subsystems and guide their exploration of the software system. There are many available properties... which properties matter most for his...

324

E-Print Network 3.0 - asthma patients clustering Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

and emergency room... visits to see if the patients live near known sources of air pollution. Under a CDC tracking grant... , and Drexel University of Philadel phia to...

325

E-Print Network 3.0 - anytime stream clustering Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

anytime... with data that is in the form of a continuous stream rather than in a database. ... Source: Loke, Seng W. - Loke, Seng W. - Department of Computer Science and...

326

E-Print Network 3.0 - anisotropic dynamic clustering Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

editor) Spatial analysis of dynamic movements of V... Velo'v Dynamic network Spatial data. 1 Introduction Community shared bicycle programs have been... , such...

327

E-Print Network 3.0 - acpa automated cluster Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

an ASK system, a type of video-based organizational memory. The Air Campaign Planning Advisor (ACPA) uses... Advisor ACPA is composed of a Web-based ASK system linked to a...

328

E-Print Network 3.0 - acs virgo cluster Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Block Schedule 202.05 The Low Mass X-ray ... Source: Sarazin, Craig - Department of Astronomy, University of Virginia Collection: Physics 2 INSTITUTE OF PHYSICS PUBLISHING...

329

E-Print Network 3.0 - atomic clusters irradiated Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

nanotubes encapsulating cobalt crystals Summary: to the shrinkage of the irradiated nanotubes due to atom sputtering 22 and defect migration 23... by a different mechanism...

330

E-Print Network 3.0 - aqueous clusters evaluated Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

|J. Phys. Chem. Lett. 2011, 2, 25152520 Summary: )2SO4, and Na2CO3 Relative to CaCl2 and NaCl at the AirAqueous Interface Revealed by Heterodyne... Information Water...

331

E-Print Network 3.0 - aromatic hydrocarbon clusters Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

aliphatic chains as key intermediates for the nucleation Summary: to macromolecular building blocks (nanoparticles) that eventually turn into soot. Polycyclic aromatic...

332

E-Print Network 3.0 - atomic clusters Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Metals and Carbon Atoms... and carbon atoms on formation process of single-walled carbon nanotubes ... Source: Maruyama, Shigeo - Department of Mechanical Engineering,...

333

E-Print Network 3.0 - agata triple-cluster detector Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Centre de mathmatiques Collection: Mathematics 58 The Majorana Neutrinoless Double-Beta Decay Experiment Summary: . . . . . . . . . . . . . . . . . . . . . . . . . . ....

334

E-Print Network 3.0 - alpha decay cluster Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

, such as the evaluation of the beta spec- tra near their endpoint, or neutrinoless double beta decay. The latter technique Source: Piepke, Andreas G. - Department of Physics...

335

E-Print Network 3.0 - absorbers clustering outflows Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Survey of Star Forming Regions (COMPLETE) Collection: Physics 32 Effects of solar wind dynamic pressure on the ionospheric fluence during the 31 August 2005 storm Summary:...

336

E-Print Network 3.0 - acid gene cluster Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

The most common method for analyzing gene expression data is ... Source: Friedman, Nir - School of Computer Science and Engineering, Hebrew University of Jerusalem Collection:...

337

Sample Environment Plans and Progress  

E-Print Network [OSTI]

Sample Environment Plans and Progress at the SNS & HFIR SNS HFIR User Group Meeting American Conference on Neutron Scattering Ottawa, Canada June 26 ­ 30, 2010 Lou Santodonato Sample Environment Group our sample environment capabilities Feedback SHUG meetings User surveys Sample Environment Steering

Pennycook, Steve

338

Multi-object spectroscopy of low redshift EIS clusters. III. Properties of optically selected clusters  

E-Print Network [OSTI]

We have carried out an investigation of the properties of low redshift EIS clusters using both spectroscopy and imaging data. We present new redshifts for 738 galaxies in 21 ESO Imaging Survey (EIS) Cluster fields. We use the ``gap''-technique to search for significant overdensities in redshift space and to identify groups/clusters of galaxies corresponding to the original EIS matched filter cluster candidates. In this way we spectroscopically confirm 20 of the 21 cluster candidates with a matched-filter estimated redshift z_MF=0.2. We have now obtained spectroscopic redshifts for 34 EIS cluster candidates with z_MF=0.2 (see also Hansen et al., 2002; Olsen et al., 2003). Of those we spectroscopically confirm 32 with redshifts ranging from z=0.064 to 0.283. We find that: 1) the velocity dispersions of the systems range from sigma_v<=130km/s to sigma_v=1200km/s, typical of galaxy groups to rich clusters; 2) richnesses corresponding to Abell classes R<=1; and 3) concentration indices ranging from C=0.2 to C=1.2. From the analysis of the colours of the galaxy populations we find that 53% of the spectroscopically confirmed systems have a ``significant'' red sequence. These systems are on average richer and have higher velocity dispersions. We find that the colour of the red sequence galaxies matches passive stellar evolution predictions.

L. F. Olsen; C. Benoist; L. da Costa; L. Hansen; H. E. Jorgensen

2005-02-25T23:59:59.000Z

339

Course Clusters | Photosynthetic Antenna Research Center  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsruc DocumentationP-Series to User GroupInformationE-GovNatural GasCourse Clusters Course Clusters

340

Icosahedral structure in hydrogenated cobalt and nickel clusters  

SciTech Connect (OSTI)

Reactions with ammonia and with water are used to probe the geometrical structures of cobalt and nickel clusters that are saturated with hydrogen. Ammonia saturation experiments allow the determination of the number of primary NH{sub 3} binding sites on cluster surfaces, and this number shows a repeated minimization to values of 12 for many cluster sizes in the 50- to 200-atom size region. These sizes correspond to closed shells and subshells of icosahedra, suggesting that the ammoniated clusters have metal frameworks with icosahedral structure. The equilibrium reaction of the hydrogenated clusters with a single water molecule shows a pattern of local maxima in the cluster--water binding energy, with the maxima in most cases coming at clusters having one metal atom more than those showing minima in ammonia binding. This correlation suggests that nonammoniated clusters likewise have icosahedral structure, and is consistent with the nature of the metal--water interaction. Some of the larger clusters do not show clear evidence for icosahedral structure at room temperature, although they begin to do so at elevated temperature. Annealing experiments suggest that many of these clusters are icosahedral in their most stable configuration at room temperature, although the 147-atom nickel cluster is not. In general, hydrogenation enhances the icosahedral features in the ammonia and water binding patterns compared to those seen for bare clusters, and extends the cluster size region over which icosahedral structure is evident.

Klots, T.D.; Winter, B.J.; Parks, E.K.; Riley, S.J. (Chemistry Division, Argonne National Laboratory, Argonne, Illinois (USA))

1991-12-15T23:59:59.000Z

Note: This page contains sample records for the topic "four-stage cluster sampling" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Power spectrum normalization from the local abundance of rich clusters of galaxies  

E-Print Network [OSTI]

The number density of rich galaxy clusters still provides the most robust way of normalizing the power spectrum of dark matter perturbations on scales relevant to large-scale structure. We revisit this constraint in light of several recent developments: (1) the availability of well-defined samples of local clusters with relatively accurate X-ray temperatures; (2) new theoretical mass functions for dark matter haloes which provide a good fit to large numerical simulations; (3) more accurate mass-temperature relations from larger catalogs of hydrodynamical simulations; (4) the requirement to consider closed as well as open and flat cosmologies to obtain full multi-parameter likelihood constraints for CMB and SNe studies. We present a new sample of clusters drawn from the literature and use this sample to obtain improved results on sigma_8, the normalization of the matter power spectrum on scales of 8 h^{-1} Mpc, as a function of the matter density and cosmological constant in a Universe with general curvature. We discuss our differences with previous work, and the remaining major sources of uncertainty. Final results on the 68 per cent confidence region, approximately independent of power spectrum shape, can be expressed as constraints on sigma at an appropriate cluster normalization scale R_Cl. We provide fitting formulas for R_Cl and sigma(R_Cl) for general cosmologies, as well as for sigma_8 as a function of cosmology and shape parameter Gamma. For flat models we find approximately sigma_8 \\simeq 0.495^{+0.034}_{-0.037}) Omega_M^{-0.60} for Gamma=0.23, where the error bar is dominated by uncertainty in the mass-temperature relation.

E. Pierpaoli; D. Scott; M. White

2001-09-27T23:59:59.000Z

342

Stack sampling apparatus  

SciTech Connect (OSTI)

An apparatus for obtaining samples from a structure includes a support member, at least one stabilizing member, and at least one moveable member. The stabilizing member has a first portion coupled to the support member and a second portion configured to engage with the structure to restrict relative movement between the support member and the structure. The stabilizing member is radially expandable from a first configuration where the second portion does not engage with a surface of the structure to a second configuration where the second portion engages with the surface of the structure.

Lind, Randall F; Lloyd, Peter D; Love, Lonnie J; Noakes, Mark W; Pin, Francois G; Richardson, Bradley S; Rowe, John C

2014-09-16T23:59:59.000Z

343

September 2004 Water Sampling  

Office of Legacy Management (LM)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "ofEarlyEnergyDepartment ofDepartment ofofOxford SiteToledoSampling at the Grand Junction, Colorado, Disposal

344

September 2004 Water Sampling  

Office of Legacy Management (LM)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "ofEarlyEnergyDepartment ofDepartment ofofOxford SiteToledoSampling at the Grand Junction, Colorado,

345

September 2004 Water Sampling  

Office of Legacy Management (LM)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "ofEarlyEnergyDepartment ofDepartment ofofOxford SiteToledoSampling at the Grand Junction, Colorado,and

346

September 2004 Water Sampling  

Office of Legacy Management (LM)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "ofEarlyEnergyDepartment ofDepartment ofofOxford SiteToledoSampling at the Grand Junction, Colorado,andOld

347

September 2004 Water Sampling  

Office of Legacy Management (LM)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "ofEarlyEnergyDepartment ofDepartment ofofOxford SiteToledoSampling at the Grand Junction, Colorado,andOld

348

September 2004 Water Sampling  

Office of Legacy Management (LM)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "ofEarlyEnergyDepartment ofDepartment ofofOxford SiteToledoSampling at the Grand Junction, Colorado,andOldOld

349

September 2004 Water Sampling  

Office of Legacy Management (LM)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "ofEarlyEnergyDepartment ofDepartment ofofOxford SiteToledoSampling at the Grand Junction,

350

September 2004 Water Sampling  

Office of Legacy Management (LM)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "ofEarlyEnergyDepartment ofDepartment ofofOxford SiteToledoSampling at the Grand Junction,Groundwater and

351

Sample Changes and Issues  

Annual Energy Outlook 2013 [U.S. Energy Information Administration (EIA)]

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) " ,"ClickPipelines AboutDecemberSteamYear Jan FebThousand Cubic Feet)Year JanC.9.3. Receipts8.160Sample

352

September 2004 Water Sampling  

Office of Legacy Management (LM)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "ofEarlyEnergyDepartment ofDepartment ofof EnergyYou$0.C.Green River, Utah, DisposalRulison,Sampling at

353

September 2004 Water Sampling  

Office of Legacy Management (LM)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "ofEarlyEnergyDepartment ofDepartment ofof EnergyYou$0.C.Green River, Utah, DisposalRulison,Sampling at4

354

September 2004 Water Sampling  

Office of Legacy Management (LM)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "ofEarlyEnergyDepartment ofDepartment ofof EnergyYou$0.C.Green River, Utah, DisposalRulison,Sampling

355

September 2004 Water Sampling  

Office of Legacy Management (LM)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "ofEarlyEnergyDepartment ofDepartment ofof EnergyYou$0.C. 20545 OCT 28Sacandaga SiteSep NovWater Sampling

356

September 2004 Water Sampling  

Office of Legacy Management (LM)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "ofEarlyEnergyDepartment ofDepartment ofof EnergyYou$0.C. 20545 OCT 28Sacandaga SiteSep NovWaterSampling

357

Stellar rotation, binarity, and lithium in the open cluster IC4756  

E-Print Network [OSTI]

An important aspect in the evolutionary scenario of cool stars is their rotation and the rotationally induced magnetic activity and interior mixing. Stars in open clusters are particularly useful tracers for these aspects because of their known ages. We aim to characterize the open cluster IC4756 and measure stellar rotation periods and surface differential rotation for a sample of its member stars. Thirty-seven cluster stars were observed continuously with the CoRoT satellite for 78 days in 2010. Follow-up high-resolution spectroscopy of the CoRoT targets and deep Str\\"omgren $uvby\\beta$ and H$\\alpha$ photometry of the entire cluster were obtained with our robotic STELLA facility and its echelle spectrograph and wide-field imager, respectively. We determined high-precision photometric periods for 27 of the 37 CoRoT targets and found values between 0.155 and 11.4 days. Twenty of these are rotation periods. Twelve targets are spectroscopic binaries of which 11 were previously unknown; orbits are given for six ...

Strassmeier, Klaus G; Granzer, Thomas; Bihain, Gabriel; Weber, Michael; Barnes, Sydney A

2015-01-01T23:59:59.000Z

358

GeV Gamma-ray Flux Upper Limits from Clusters of Galaxies  

E-Print Network [OSTI]

The detection of diffuse radio emission associated with clusters of galaxies indicates populations of relativistic leptons infusing the intracluster medium. Those electrons and positrons are either injected into and accelerated directly in the intracluster medium, or produced as secondary pairs by cosmic-ray ions scattering on ambient protons. Radiation mechanisms involving the energetic leptons together with decay of neutral pions produced by hadronic interactions have the potential to produce abundant GeV photons. Here, we report on the search for GeV emission from clusters of galaxies using data collected by the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (Fermi) from August 2008 to February 2010. Thirty-three galaxy clusters have been selected according to their proximity and high mass, X-ray flux and temperature, and indications of non-thermal activity for this study. We report upper limits on the photon flux in the range 0.2-100 GeV towards a sample of observed clusters (typical va...

al., M Ackermann et

2010-01-01T23:59:59.000Z

359

Constraining amplitude and slope of the mass fluctuation spectrum using cluster baryon mass function  

E-Print Network [OSTI]

We derive the baryon mass function for a complete sample of low-redshift clusters and argue that it is an excellent proxy for the total mass function if the ratio f_b=M_b/M_tot in all clusters is close to its universal value, Omega_b/Omega_M. Under this assumption, the baryon mass function can be used to constrain the amplitude and slope of the density fluctuations power spectrum on cluster scales. This method does not use observational determinations of the total mass and thus bypasses major uncertainties in the traditional analyses based on the X-ray temperature function. However, it is sensitive to possible systematic variations of the baryon fraction as a function of cluster mass. Adapting a weak dependence f_b(M) suggested by observations and numerical simulations by Bialek et al., we derive sigma_8=0.72+-0.04 and the shape parameter Omega_M*h=0.13+-0.07, in good agreement with a number of independent methods. We discuss the sensitivity of these values to other cosmological parameters and to different assumptions about variations in f_b.

A. Voevodkin; A. Vikhlinin

2003-10-22T23:59:59.000Z

360

$XMM-Newton$ $?$ project: III. Gas mass fraction shape in high redshift clusters  

E-Print Network [OSTI]

We study the gas mass fraction, $f\\_{\\rm gas},$ behavior in $XMM-Newton$ $\\Omega$ project. The typical $f\\_{\\rm gas}$ shape of high redshift galaxy clusters follows the global shape inferred at low redshift quite well. This result is consistent with the gravitational instability picture leading to self similar structures for both the dark and baryonic matter. However, the mean $f\\_{\\rm gas} in distant clusters shows some differences to local ones, indicating a departure from strict scaling. This result is consistent with the observed evolution in the luminosity-temperature relation. We quantitatively investigate this departure from scaling laws. Within the local sample we used, a moderate but clear variation of the amplitude of the gas mass fraction with temperature is found, a trend that weakens in the outer regions. These variations do not explain departure from scaling laws of our distant clusters. An important implication of our results is that the gas fraction evolution, a test of the cosmological parameters, can lead to biased values when applied at radii smaller than the virial radius. From our $XMM$ clusters, the apparent gas fraction at the virial radius is consistent with a non-evolving universal value in a high matter density model and not with a concordance.

Rachida Sadat; Alain Blanchard; Sebastien C. Vauclair; David H. Lumb; James Bartlett; A. K. Romer; Jean-Philippe Bernard; Michel Boer; Philippe Marty; Jukka Nevalainen; Douglas J. Burke; C. A. Collins; Robert C. Nichol

2005-03-19T23:59:59.000Z

Note: This page contains sample records for the topic "four-stage cluster sampling" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

An explanation for long flares from extragalactic globular cluster X-ray sources  

E-Print Network [OSTI]

Repeatedly flaring X-ray binaries have recently been discovered in NGC 4697 by Sivakoff and collaborators. We show that these flares can be explained as the result of eccentric binaries in globular clusters which accrete more rapidly at periastron than during the rest of the binary orbit. We show that theoretical timescales for producing eccentricities and circularising the binaries are consistent with what is needed to produce the observed population of flaring sources, although the circularisation timescales are highly uncertain on both observational and theoretical grounds. This model makes two clear theoretical predictions (1) the flares should be seen to be strictly periodic if adequate sampling is provided, and that periodicity should be of approximately 15 hours (2) this class of flaring behaviour should be seen only in globular cluster sources, and predominantly in the densest globular clusters. We also test the model for producing eccentricities through fly-by's of a third star near the binary in a globular cluster against a much larger database of millisecond pulsar observations than has been used in past work, and find that the theoretical cross sections for producing eccentricity in binaries are in reasonable agreement with most of the data, provided that the pulsar ages are about $4\\times10^9$ years.

Thomas J. Maccarone

2005-09-21T23:59:59.000Z

362

Spectral energy distributions and age estimates of 104 M31 globular clusters  

E-Print Network [OSTI]

We present photometry of 104 M31 globular clusters (GCs) and GC candidates in 15 intermediate-band filters of the Beijing-Arizona-Taiwan-Connecticut (BATC) photometric system. The GCs and GC candidates were selected from the Revised Bologna Catalog (v.3.5). We obtain the cluster ages by comparing the photometric data with up-to-date theoretical synthesis models. The photometric data used are {\\sl GALEX} far- and near-ultraviolet and 2MASS near-infrared $JHK_{\\rm s}$ magnitudes, combined with optical photometry. The ages of our sample clusters cover a large range, although most clusters are younger than 10 Gyr. Combined with the ages obtained in our series of previous papers focusing on the M31 GC system, we present the full M31 GC age distribution. The M31 GC system contains populations of young and intermediate-age GCs, as well as the `usual' complement of well-known old GCs, i.e., GCs of similar age as the majority of the Galactic GCs. In addition, young GCs (and GC candidates) are distributed nearly unifor...

Wang, Song; Ma, Jun; de Grijs, Richard; Zhou, Xu

2010-01-01T23:59:59.000Z

363

A DETAILED STATISTICAL ANALYSIS OF THE MASS PROFILES OF GALAXY CLUSTERS  

SciTech Connect (OSTI)

The distribution of mass in the halos of galaxies and galaxy clusters has been probed observationally, theoretically, and in numerical simulations, yet there is still confusion about which of several suggested parameterized models is the better representation, and whether these models are universal. We use the temperature and density profiles of the intracluster medium as measured by X-ray observations of 11 relaxed galaxy clusters to investigate mass models for the halo using a thorough Bayesian statistical analysis. We make careful comparisons between two- and three-parameter models, including the issue of a universal third parameter. We find that, of the two-parameter models, the Navarro-Frenk-White (NFW) is the best representation, but we also find moderate statistical evidence that a generalized three-parameter NFW model with a freely varying inner slope is preferred, despite penalizing against the extra degree of freedom. There is a strong indication that this inner slope needs to be determined for each cluster individually, i.e., some clusters have central cores and others have steep cusps. The mass-concentration relation of our sample is in reasonable agreement with predictions based on numerical simulations.

Host, Ole [Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT (United Kingdom); Hansen, Steen H. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark)

2011-07-20T23:59:59.000Z

364

Fluid sampling tool  

DOE Patents [OSTI]

A fluid sampling tool is described for sampling fluid from a container. The tool has a fluid collecting portion which is drilled into the container wall, thereby affixing it to the wall. The tool may have a fluid extracting section which withdraws fluid collected by the fluid collecting section. The fluid collecting section has a fluted shank with an end configured to drill a hole into a container wall. The shank has a threaded portion for tapping the borehole. The shank is threadably engaged to a cylindrical housing having an inner axial passageway sealed at one end by a septum. A flexible member having a cylindrical portion and a bulbous portion is provided. The housing can be slid into an inner axial passageway in the cylindrical portion and sealed to the flexible member. The bulbous portion has an outer lip defining an opening. The housing is clamped into the chuck of a drill, the lip of the bulbous section is pressed against a container wall until the shank touches the wall, and the user operates the drill. Wall shavings (kerf) are confined in a chamber formed in the bulbous section as it folds when the shank advances inside the container. After sufficient advancement of the shank, an o-ring makes a seal with the container wall. 6 figs.

Garcia, A.R.; Johnston, R.G.; Martinez, R.K.

1999-05-25T23:59:59.000Z

365

High density cluster jet target for storage ring experiments  

E-Print Network [OSTI]

The design and performance of a newly developed cluster jet target installation for hadron physics experiments are presented which, for the first time, is able to generate a hydrogen cluster jet beam with a target thickness of above $10^{15}\\,\\mathrm{atoms/cm}^2$ at a distance of two metres behind the cluster jet nozzle. The properties of the cluster beam and of individual clusters themselves are studied at this installation. Special emphasis is placed on measurements of the target beam density as a function of the relevant parameters as well as on the cluster beam profiles. By means of a time-of-flight setup, measurements of the velocity of single clusters and velocity distributions were possible. The complete installation, which meets the requirements of future internal fixed target experiments at storage rings, and the results of the systematic studies on hydrogen cluster jets are presented and discussed.

Alexander Täschner; Esperanza Köhler; Hans-Werner Ortjohann; Alfons Khoukaz

2011-11-02T23:59:59.000Z

366

Using Clustering to extract Personality Information from socio economic data.  

E-Print Network [OSTI]

Using Clustering to extract Personality Information from socio economic data. Alexandros Ladas, Uwe. Keywords-component; Data Mining; Clustering; Behavior Mining; Personality Psychology; I. INTRODUCTION psychological information regarding the Personalities of the individuals in order to enhance Data Mining methods

Aickelin, Uwe

367

Beltrami Equation and Cluster Lensing: Characteristic Equations and Applications  

E-Print Network [OSTI]

Arclets in clusters of galaxies can be used to determine the lens mapping and not only to constrain the mass density of the cluster. Multiply imaged arclets are therefore easily identified without further modelling.

Schramm; T

1995-07-24T23:59:59.000Z

368

Weak lensing flexion as a probe of galaxy cluster substructure  

E-Print Network [OSTI]

Measuring galaxy cluster total masses and the amount of dark matter substructure within galaxy cluster haloes is a fundamental probe of the ACDM model of structure formation, as well as the interactions between baryonic ...

Cain, Benjamin Martin

2011-01-01T23:59:59.000Z

369

Building dwarf galaxies out of merged young star clusters  

E-Print Network [OSTI]

Young star clusters in interacting galaxies are often found in groups or clusters of star clusters containing up to 100 single clusters. In our project we study the future fate of these clusters of star clusters. We find that the star clusters merge on time scales of a few dynamical crossing times of the super-cluster. The resulting merger object has similarities with observed dwarf ellipticals (dE). Furthermore, if destructive processes like tidal heating, dynamical friction or interaction with disc or bulge of the parent galaxy are taken into account our merger objects may evolve into objects resembling dwarf spheroidal galaxies (dSph), without the need of a high dark matter content.

M. Fellhauer

2001-06-22T23:59:59.000Z

370

Spatial clustering of pixels of a multispectral image  

DOE Patents [OSTI]

A method and system for clustering the pixels of a multispectral image is provided. A clustering system computes a maximum spectral similarity score for each pixel that indicates the similarity between that pixel and the most similar neighboring. To determine the maximum similarity score for a pixel, the clustering system generates a similarity score between that pixel and each of its neighboring pixels and then selects the similarity score that represents the highest similarity as the maximum similarity score. The clustering system may apply a filtering criterion based on the maximum similarity score so that pixels with similarity scores below a minimum threshold are not clustered. The clustering system changes the current pixel values of the pixels in a cluster based on an averaging of the original pixel values of the pixels in the cluster.

Conger, James Lynn

2014-08-19T23:59:59.000Z

371

Studies of nearby poor clusters - A3574 and S753  

SciTech Connect (OSTI)

Photometric and spectroscopic data are presented for two clusters, A3574 and S753, belonging to the Centaurus concentration of galaxies. The masses of the clusters are estimated at 1.5 x 10 to the 14th solar masses; no evidence of substructure has been detected in either cluster. The solution of a two-body linear orbit suggests that the clusters do not form a bound system, although the result is marginal. 60 refs.

Willmer, C.N.A.; Focardi, P.; Chan, R.; Pellegrini, P.S.; Da Costa, N.L. (Observatorio Nacional do Brasil, Rio de Janeiro (Brazil))

1991-01-01T23:59:59.000Z

372

Exploratory Clusters of Student Technology Participation with Multivariate Regression Trees  

E-Print Network [OSTI]

technology use in the context of a high school statistics curriculum, and generates exploratory clusters of that usage

Skipper, Peter Tyrel

2014-01-01T23:59:59.000Z

373

Energy Proportionality and Performance in Data Parallel Computing Clusters  

E-Print Network [OSTI]

8] presented a hybrid datacenter model with two-class nodesbe ideally zero. Thus, a datacenter cluster still needs to

Kim, Jinoh

2011-01-01T23:59:59.000Z

374

Molecular Cluster Perturbation Theory. I. Formalism  

E-Print Network [OSTI]

We present second-order molecular cluster perturbation theory (MCPT(2)), a linear scaling methodology to calculate arbitrarily large systems with explicit calculation of individual wavefunctions in a coupled-cluster framework. This new MCPT(2) framework uses coupled-cluster perturbation theory and an expansion in terms of molecular dimer interactions to obtain molecular wavefunctions that are infinite-order in both the electronic fluctuation operator and all possible dimer (and products of dimers) interactions. The MCPT(2) framework has been implemented in the new SIA/Aces4 parallel architecture, making use of the advanced dynamic memory control and fine grained parallelism to perform very large explicit molecular cluster calculations. To illustrate the power of this method, we have computed energy shifts, lattice site dipole moments, and harmonic vibrational frequencies via explicit calculation of the bulk system for the polar and non-polar polymorphs of solid hydrogen fluoride. The explicit lattice size (without using any periodic boundary conditions) was expanded up to 1,000 HF molecules, with 32,000 basis functions and 10,000 electrons. Our obtained HF lattice site dipole moments and harmonic vibrational frequencies agree well with the existing literature.

Jason N. Byrd; Nakul Jindal; Robert W. Molt, Jr.; Rodney J. Bartlett; Beverly A. Sanders; Victor F. Lotrich

2015-03-23T23:59:59.000Z

375

Modeling the Energy Efficiency of Heterogeneous Clusters  

E-Print Network [OSTI]

on heterogeneous clusters ­ Unexplored from energy-time performance perspective 10-Sep-14 ICPP 2014 7 #12;Objectiveth September 2014 43rd International Conference on Parallel Processing, Minneapolis, MN, USA #12;Outline · Motivation · Objective · Methodology · Analysis · Conclusions 10-Sep-14 2ICPP 2014 #12;Energy

Teo, Yong-Meng

376

New nuclear three-body clusters ?{NN}  

E-Print Network [OSTI]

Binding energies of three-body systems of the type \\phi+2N are estimated. Due to the strong attraction between \\phi-meson and nucleon, suggested in different approaches, bound states can appear in systems like \\phi+np (singlet and triplet) and \\phi+pp. This indicates the principal possibility of the formation of new nuclear clusters.

Vladimir B. Belyaev; Werner Sandhas; Ivan I. Shlyk

2007-07-31T23:59:59.000Z

377

Molecular Cluster Perturbation Theory. I. Formalism  

E-Print Network [OSTI]

We present second-order molecular cluster perturbation theory (MCPT(2)), a methodology to calculate arbitrarily large systems with explicit calculation of individual wavefunctions in a coupled-cluster framework. This new MCPT(2) framework uses coupled-cluster perturbation theory and an expansion in terms of molecular dimer interactions to obtain molecular wavefunctions that are infinite-order in both the electronic fluctuation operator and all possible dimer (and products of dimers) interactions. The MCPT(2) framework has been implemented in the new SIA/ACES parallel architecture, making use of the advanced dynamic memory control and fine grained parallelism to perform very large explicit molecular cluster calculations. To illustrate the power of this method, we have computed energy shifts and lattice site dipole moments via explicit calculation of the bulk system for the polar and non-polar configurations of solid hydrogen fluoride. The explicit lattice size without periodic boundary conditions was expanded up to 1,000 HF molecules, with 32,000 basis functions and 10,000 electrons. Our obtained HF lattice site dipole moments of 2.51 and 2.49 Debye (for the polar and non-polar configurations, respectively) are in good agreement with the existing literature values of 2.51 and 2.47.

Jason N. Byrd; Nakul Jindal; Robert W. Molt, Jr.; Rodney J. Bartlett; Beverly A. Sanders; Victor F. Lotrich

2014-09-06T23:59:59.000Z

378

Optimizing Path Query Performance: Graph Clustering Strategies  

E-Print Network [OSTI]

ywh@us.ibm.com Ning Jingz Changsha Institute of Technology jning@eecs.umich.edu Elke A. Rundensteinerx not incur any run-time cost, requires no auxiliary data structures, and is complimentary to many of the performance of these graph clustering techniques using an actual city road network as well as randomly

379

College of Engineering High Performance Computing Cluster  

E-Print Network [OSTI]

College of Engineering High Performance Computing Cluster Policy and Procedures COE-HPC-01 and registered as requiring high performance computing; the course identification/registrations process the College High Performance Computing system will need register for system access by visiting http

Demirel, Melik C.

380

Clusters in Very High Energy Cosmic Rays  

E-Print Network [OSTI]

Arrival directions of cosmic rays with the energy E>4.10^{19} eV are analyzed by using data of the Yakutsk and AGASA (Japan) extensive air showers (EAS) arrays. It is supposed that the clusters can be formed as a result of decay of superheavy particles. The consequences of this supposition compare with experimental data.

A. A. Mikhailov

2004-03-19T23:59:59.000Z

Note: This page contains sample records for the topic "four-stage cluster sampling" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Molecular Cluster Perturbation Theory. I. Formalism  

E-Print Network [OSTI]

We present second-order molecular cluster perturbation theory (MCPT(2)), a linear scaling methodology to calculate arbitrarily large systems with explicit calculation of individual wavefunctions in a coupled-cluster framework. This new MCPT(2) framework uses coupled-cluster perturbation theory and an expansion in terms of molecular dimer interactions to obtain molecular wavefunctions that are infinite-order in both the electronic fluctuation operator and all possible dimer (and products of dimers) interactions. The MCPT(2) framework has been implemented in the new SIA/ACES parallel architecture, making use of the advanced dynamic memory control and fine grained parallelism to perform very large explicit molecular cluster calculations. To illustrate the power of this method, we have computed energy shifts and lattice site dipole moments via explicit calculation of the bulk system for the polar and non-polar polymorphs of solid hydrogen fluoride. The explicit lattice size without periodic boundary conditions was expanded up to 1,000 HF molecules, with 32,000 basis functions and 10,000 electrons. Our obtained HF lattice site dipole moments and harmonic vibrational frequencies agree well with the existing literature.

Jason N. Byrd; Nakul Jindal; Robert W. Molt, Jr.; Rodney J. Bartlett; Beverly A. Sanders; Victor F. Lotrich

2015-01-14T23:59:59.000Z

382

BOUNDS FOR SPECTRAL CLUSTERS HART F. SMITH  

E-Print Network [OSTI]

Lq BOUNDS FOR SPECTRAL CLUSTERS HART F. SMITH Abstract. In these notes, we review recent results] establish the same estimates under the assumption that the metric is C1,1. It is known by examples of Smith to the wave equation. The author was supported in part by NSF grant DMS-0140499. 1 #12;2 HART F. SMITH

Smith, Hart F.

383

February 22, 1998 Clustering ECG Complexes Using  

E-Print Network [OSTI]

LU TP 98­1 February 22, 1998 Clustering ECG Complexes Using Hermite Functions and Self Transactions on Biomedical Engineering Abstract: An integrated method for identifying and classifying ECG for analysis and interpretation of ECGs have been subject to intense research for nearly four decades

Lunds Universitet,

384

clusterMaker: a multi-algorithm clustering plugin for Cytoscape  

E-Print Network [OSTI]

than 40% of all known proteins lack any annota- tions withinprotein BH2212 from Bacillus halodurans (gi:15614775) lacksprotein interaction data sets have been clustered to identify stable complexes, but scientists lack

2011-01-01T23:59:59.000Z

385

From nuclear clusters to halo globulars: Star clusters as basic galactic building blocks  

E-Print Network [OSTI]

I assess the similarities and differences between the star-formation modes in quiescent spiral galaxies versus those in violent starburst regions, including galactic nuclei. As opposed to the quiescent star-formation mode, current empirical evidence on the star-formation processes in the extreme, high-pressure environments induced by galaxy encounters strongly suggests that star cluster formation is an important and perhaps even the dominant mode of star formation in such starburst events. This implies that by using star clusters as unique diagnostic probes, we can trace a galaxy's most violent star formation history very well, at least for the past few Gyr. The sizes, luminosities, and mass estimates of the young massive star clusters are entirely consistent with what is expected for young Milky Way-type globular clusters (GCs). Recent evidence lends support to the scenario that GCs, which were once thought to be the oldest building blocks of galaxies, are still forming today.

Richard de Grijs

2006-09-05T23:59:59.000Z

386

Size-selected Metal Cluster Deposition on Oxide Surfaces: Impact Dynamics and Supported Cluster Chemistry  

E-Print Network [OSTI]

Lens Quadrupole Ion Guide 3 Focusing Lens Deposition Stage Electron Multiplier Isolation Valve4 Au3 Au2 Au Constant signal = constant sticking coefficient ~1.0 No shifts with cluster size

Anderson, Scott L.

387

Fluid sampling tool  

DOE Patents [OSTI]

The invention includes a rotatable tool for collecting fluid through the wall of a container. The tool includes a fluid collection section with a cylindrical shank having an end portion for drilling a hole in the container wall when the tool is rotated, and a threaded portion for tapping the hole in the container wall. A passageway in the shank in communication with at least one radial inlet hole in the drilling end and an opening at the end of the shank is adapted to receive fluid from the container. The tool also includes a cylindrical chamber affixed to the end of the shank opposite to the drilling portion thereof for receiving and storing fluid passing through the passageway. The tool also includes a flexible, deformable gasket that provides a fluid-tight chamber to confine kerf generated during the drilling and tapping of the hole. The invention also includes a fluid extractor section for extracting fluid samples from the fluid collecting section.

Johnston, Roger G. (Los Alamos, NM); Garcia, Anthony R. E. (Espanola, NM); Martinez, Ronald K. (Santa Cruz, NM)

2001-09-25T23:59:59.000Z

388

Aalborg Universitet Hierarchical Control for Multiple DC Microgrids Clusters  

E-Print Network [OSTI]

Aalborg Universitet Hierarchical Control for Multiple DC Microgrids Clusters Shafiee, Qobad Control for Multiple DC Microgrids Clusters. I E E E Transactions on Energy Conversion. General rights, J. C. Vasquez, and J. M. Guerrero, "Hierarchical Control for Multiple DC-Microgrids Clusters," IEEE

Vasquez, Juan Carlos

389

Sticking properties of water clusters Sebastien Zamith1,2  

E-Print Network [OSTI]

]. The pos- itively charged, protonated water clusters are produced in a gas aggregation source. Right afterSticking properties of water clusters S´ebastien Zamith1,2 , Pierre Feiden1,2 , Pierre Labastie1) Absolute attachment cross sections of single water molecules onto mass selected protonated water clusters

Paris-Sud XI, Université de

390

HEAVY GOLD CLUSTER BEAMS production and identi cation  

E-Print Network [OSTI]

. This method is based on the acceleration of the clusters to high energy (MeV) and on the measurement, after to select heavy Aun cluster beams for applications at low energy (keV) in mass spectrometry. 1. Introduction, with a multianode detector 7], the number of constituents coming out of the foil. High energy clusters, accelerated

Boyer, Edmond

391

Understanding Complex Network Attack Graphs through Clustered Adjacency Matrices  

E-Print Network [OSTI]

Understanding Complex Network Attack Graphs through Clustered Adjacency Matrices Steven Noel}@gmu.edu Abstract We apply adjacency matrix clustering to network attack graphs for attack correlation, prediction, and hypothesizing. We self-multiply the clustered adjacency matrices to show attacker reachability across

Noel, Steven

392

A Hierarchical Checkpointing Protocol for Parallel Applications in Cluster Federations  

E-Print Network [OSTI]

A Hierarchical Checkpointing Protocol for Parallel Applications in Cluster Federations S federation. As a cluster federation comprises of a large number of nodes, there is a high probability fits to the characteristics of a cluster federation (large number of nodes, high latency and low

Paris-Sud XI, Université de

393

Photoelectron imaging of large anionic methanol clusters: ,,n70460...  

E-Print Network [OSTI]

been described elsewhere.9 Methanol cluster anions were produced by passing argon through a reservoirPhotoelectron imaging of large anionic methanol clusters: ,,MeOH...n - ,,n�70­460... Aster Kammrath Electron solvation in methanol anion clusters, MeOH n - n 70­460 , is studied by photoelectron imaging. Two

Neumark, Daniel M.

394

Energy Conservation in Heterogeneous Server Clusters Taliver Heath  

E-Print Network [OSTI]

Energy Conservation in Heterogeneous Server Clusters #3; Taliver Heath Dept. of Computer Science, measurement Keywords Energy conservation, server clusters, heterogeneity #3; This research has been supported.g., [3, 4, 9, 21]) and dynamic cluster recon#12;guration for energy conservation without per- formance

Bianchini, Ricardo

395

cars: A New Code Generation Framework for Clustered ILP Processors  

E-Print Network [OSTI]

â??glu z Ashok Agrawala \\Lambda y Department of Electrical & Computer Engineering z T. J. Watson Research are characterized by a large number of non­centralized on­chip re­ sources grouped into clusters. Traditional code we present cars, a code generation framework for Clustered ILP processors, which combines the cluster

Kailas, Krishnan

396

Mass spectra and theoretical modeling of Li Krn clusters  

E-Print Network [OSTI]

high intensity, with respect to neighboring ones, is also observed for the clusters with 34 argon±theoretical project which involves the study of metal ion-doped noble gas clusters of the type MXn (M metal ion and X (In, Al) [9], carbon [10,11] and transition metals (Ti, Fe, Ni, Pt) [12± 14]. Clusters involving

Farantos, Stavros C.

397

The Sustainability FYE Cluster The Sustainability FYE Cluster will make sustainable urban living a core experience for First  

E-Print Network [OSTI]

The Sustainability FYE Cluster The Sustainability FYE Cluster will make sustainable urban living University. The Sustainability community infuses the learning-living community with practical and theoretical approaches to sustainable living, merging students' living community with unique academic and field

398

THE BURST CLUSTER: DARK MATTER IN A CLUSTER MERGER ASSOCIATED WITH THE SHORT GAMMA-RAY BURST, GRB 050509B  

E-Print Network [OSTI]

We have identified a merging galaxy cluster with evidence of two distinct subclusters. The X-ray and optical data suggest that the subclusters are presently moving away from each other after closest approach. This cluster ...

Dahle, H.

399

Carbon in Red Giants in Globular Clusters and Dwarf Spheroidal Galaxies  

E-Print Network [OSTI]

We present carbon abundances of red giants in Milky Way globular clusters and dwarf spheroidal galaxies (dSphs). Our sample includes measurements of carbon abundances for 154 giants in the clusters NGC 2419, M68, and M15 and 398 giants in the dSphs Sculptor, Fornax, Ursa Minor, and Draco. This sample doubles the number of dSph stars with measurements of [C/Fe]. The [C/Fe] ratio in the clusters decreases with increasing luminosity above log(L/L_sun) ~= 1.6, which can be explained by deep mixing in evolved giants. The same decrease is observed in dSphs, but the initial [C/Fe] of the dSph giants is not uniform. Stars in dSphs at lower metallicities have larger [C/Fe] ratios. We hypothesize that [C/Fe] (corrected to the initial carbon abundance) declines with increasing [Fe/H] due to the metallicity dependence of the carbon yield of asymptotic giant branch stars and due to the increasing importance of Type Ia supernovae at higher metallicities. We also identified 11 very carbon-rich giants (8 previously known) in...

Kirby, Evan N; Zhang, Andrew J; Deng, Michelle; Cohen, Judith G; Guhathakurta, Puragra; Shetrone, Matthew D; Lee, Young Sun; Rizzi, Luca

2015-01-01T23:59:59.000Z

400

The Clustering Characteristics of HI-Selected Galaxies from the 40% ALFALFA Survey  

E-Print Network [OSTI]

The 40% Arecibo Legacy Fast ALFA (ALFALFA) survey catalog (\\alpha.40) of approximately 10,150 HI-selected galaxies is used to analyze the clustering properties of gas-rich galaxies. By employing the Landy-Szalay estimator and a full covariance analysis for the two-point galaxy-galaxy correlation function, we obtain the real-space correlation function and model it as a power law, \\xi(r) = (r/r_0)^(-\\gamma), on scales less than 10 h^{-1} Mpc. As the largest sample of blindly HI-selected galaxies to date, \\alpha.40 provides detailed understanding of the clustering of this population. We find \\gamma = 1.51 +/- 0.09 and r_0 = 3.3 +0.3, -0.2 h^{-1} Mpc, reinforcing the understanding that gas-rich galaxies represent the most weakly clustered galaxy population known; we also observe a departure from a pure power law shape at intermediate scales, as predicted in \\Lambda CDM halo occupation distribution models. Furthermore, we measure the bias parameter for the \\alpha.40 galaxy sample and find that HI galaxies are seve...

Martin, Ann M; Haynes, Martha P; Guzzo, Luigi

2012-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "four-stage cluster sampling" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Specified assurance level sampling procedure  

SciTech Connect (OSTI)

In the nuclear industry design specifications for certain quality characteristics require that the final product be inspected by a sampling plan which can demonstrate product conformance to stated assurance levels. The Specified Assurance Level (SAL) Sampling Procedure has been developed to permit the direct selection of attribute sampling plans which can meet commonly used assurance levels. The SAL procedure contains sampling plans which yield the minimum sample size at stated assurance levels. The SAL procedure also provides sampling plans with acceptance numbers ranging from 0 to 10, thus, making available to the user a wide choice of plans all designed to comply with a stated assurance level.

Willner, O.

1980-11-01T23:59:59.000Z

402

Tracking Cluster Debris (TraCD) I: dissolution of clusters and searching the Solar cradle  

E-Print Network [OSTI]

Here we focus on the dynamical aspect and given that most of the stars in the Milky Way have been born in stellar associations or clusters that have lived a few Myr up to several Gyr, we focus on the evolution of star clusters. We have carried out our simulations in two steps: 1) we have created a Galactic disc dynamically as close to observations as possible and 2) we have evolved three sets of stellar clusters with masses of 400, 1000 and 15000 Msun to dissolution. The birth location of these sets was 4, 6, 8 and 10 kpc for the 400 and 1000 Msun clusters and 4, 6, 8, 10 and 12 kpc for the 15000 Msun. We have focussed our efforts on studying the state of these escapers after 4.5 Gyr of evolution in the Solar annulus, i.e. 7.5 < Rgc < 8.5 kpc. We have also analysed the possibility of a given star escaping from our clusters with a mass close to the mass of the Sun to end in the Solar orbit. We found by using dynamical arguments that for our 400 Msun clusters there is a 49 per cent higher chance of the Su...

Loyola, Guido R I Moyano; Hurley, Jarrod R; Gibson, Brad K

2014-01-01T23:59:59.000Z

403

Statistics of physical properties of dark matter clusters  

SciTech Connect (OSTI)

We have identified over 2000 well resolved cluster halos, and also their associated bound subhalos, from the output of 1024{sup 3} particle cosmological N-body simulation (of box size 320h{sup -1}Mpc and softening length 3.2h{sup -1}kpc). We present an algorithm to identify those halos still in the process of relaxing into dynamical equilibrium, and a detailed analysis of the integral and internal physical properties for all the halos in our sample. The majority are prolate, and tend to rotate around their minor principle axis. We find there to be no correlation between the spin and virial mass of the clusters halos and that the higher mass halos are less dynamically relaxed and have a lower concentration. Additionally, the orbital angular momentum of the substructure is typically well aligned with the rotational angular momentum of the ''host'' halo. There is also evidence of the transfer of angular momentum from subhalos to their host. Overall, we find that measured halo properties are often significantly influenced by the fraction of mass contained within substructure. Dimensionless properties do depend weakly on the ratio of halo mass (M{sub h}) to our characteristic mass scale (M{sub *} = 8 x 10{sup 14}h{sup -1}M{sub {circle_dot}}). This lack of self-similarity is in the expected sense in that, for example, ''old halos'' with M{sub h}/M{sub *} << 1 have less substructure than ''young halos'' with M{sub h}/M{sub *} >> 1.

Shaw, Laurie; /Cambridge U., Inst. of Astron.; Weller, Jochen; /Fermilab /University Coll. London; Ostriker, Jeremiah P.; /Cambridge U., Inst. of Astron. /Princeton U.; Bode, Paul; /Princeton U. Observ.

2005-09-01T23:59:59.000Z

404

Reaction of iron clusters with ammonia. I. Compositions of the ammoniated products and their implications for cluster structure  

SciTech Connect (OSTI)

Studies are described of the chemisorption of ammonia on isolated neutral iron clusters Fe/sub n/ for 2less than or equal tonless than or equal to165. Clusters are generated by laser vaporization in a continuous-flow-tube reactor, and reaction products are detected by laser-ionization time-of-flight mass spectrometry. Ammonia is found to chemisorb nondissociatively on cluster surfaces on the 1 ms time scale of these experiments. Measurements of ammonia uptake provide information on adsorption kinetics and on the number and nature of the binding sites. The ammonia binding energy is found to decrease with increasing cluster coverage. For chemically saturated clusters, the ratio of adsorbed NH/sub 3/ molecules to surface iron atoms is found to decrease with increasing cluster size, going from >1/3 for small clusters to <1/3 for n>100. Ammonia chemisorption is accompanied by a large decrease in cluster ionization potentials, as much as 2 eV for saturated clusters. At sufficiently high exposure the beginning of the formation of a second, physisorbed layer of molecules is seen. Detailed measurements of product composition under different exposure conditions give evidence for numerous changes in cluster structure throughout the growth sequence from small to large clusters. Often these structural changes involve particularly stable reaction products. Evidence for the existence of metastable structures is presented. Several possibilities for cluster structure are suggested.

Parks, E.K.; Nieman, G.C.; Pobo, L.G.; Riley, S.J.

1988-05-15T23:59:59.000Z

405

Intense emission of cluster anions from gold targets under impact of keV/u gold clusters.  

E-Print Network [OSTI]

Intense emission of cluster anions from gold targets under impact of keV/u gold clusters. M the emission yield of anionic clusters increases much faster with n than expected from simple proportionality. Accordingly, the most intense emission is observed for Au7 - : under Au9 + impact the Au7 - yield per incident

Boyer, Edmond

406

Sampling for Bacteria in Wells  

E-Print Network [OSTI]

This publication will instruct you on the proper procedures for collecting a sample from a water well for bacteriological analysis....

Lesikar, Bruce J.

2001-11-15T23:59:59.000Z

407

Sample Residential Program Term Sheet  

Broader source: Energy.gov (indexed) [DOE]

Goal DRAFT U.S. DOE Sample Residential Program Term Sheet - DRAFT Introduction is seeking to develop an energy...

408

Could merged star-clusters build up a small galaxy?  

E-Print Network [OSTI]

We investigate the behaviour of a cluster of young massive star clusters (hereafter super-cluster) in the tidal field of a host galaxy with a high-resolution particle-mesh code, Superbox. Specifically we want to establish if and how such super star-clusters merge and carry out a detailed study of the resulting merger-object. This merger-object shows either the properties of a compact spherical object or the elongated (`fluffy') shape of dSph-galaxies depending on the initial concentration of the super-cluster.

Michael Fellhauer; Pavel Kroupa

2000-02-11T23:59:59.000Z

409

The APM Galaxy Survey:- V. Catalogues of Galaxy Clusters  

E-Print Network [OSTI]

We describe the construction of catalogues of galaxy clusters from the APM Galaxy survey using an automated algorithm based on Abell-like selection criteria. We investigate the effects of varying several parameters in our selection algorithm, including the magnitude range, and radius from the cluster centre used to estimate the cluster richnesses. We quantify the accuracy of the photometric distance estimates by comparing with measured redshifts, and we investigate the stability and completeness of the resulting catalogues. We find that the angular correlation functions for different cluster catalogues are in good agreement with one another, and are also consistent with the observed amplitude of the spatial correlation function of rich clusters.

Gavin Dalton; Steve Maddox; Will Sutherland; George Efstathiou

1997-01-23T23:59:59.000Z

410

Characterizing cluster morphology using vector-valued Minkowski functionals  

E-Print Network [OSTI]

The morphology of galaxy clusters is quantified using Minkowski functionals, especially the vector-valued ones, which contain directional information and are related to curvature centroids. The asymmetry of clusters and the amount of their substructure can be characterized in a unique way using these measures. -- We briefly introduce vector-valued Minkowski functionals (also known as Querma\\ss vectors) and suggest their application to cluster data in terms of a morphological characterization of excursion sets. Furthermore, we develop robust structure functions which describe the dynamical state of a cluster and study the evolution of clusters using numerical simulations.

Claus Beisbart; Thomas Buchert

1997-11-04T23:59:59.000Z

411

CONSTRAINTS ON DARK MATTER ANNIHILATION IN CLUSTERS OF GALAXIES FROM DIFFUSE RADIO EMISSION  

SciTech Connect (OSTI)

Annihilation of dark matter can result in the production of stable Standard Model particles including electrons and positrons that, in the presence of magnetic fields, lose energy via synchrotron radiation, observable as radio emission. Galaxy clusters are excellent targets to search for or to constrain the rate of dark matter annihilation, as they are both massive and dark matter dominated. In this study, we place limits on dark matter annihilation in a sample of nearby clusters using upper limits on the diffuse radio emission, low levels of observed diffuse emission, or detections of radio mini-halos. We find that the strongest limits on the annihilation cross section are better than limits derived from the non-detection of clusters in the gamma-ray band by a factor of {approx}3 or more when the same annihilation channel and substructure model, but different best-case clusters, are compared. The limits on the cross section depend on the assumed amount of substructure, varying by as much as two orders of magnitude for increasingly optimistic substructure models as compared to a smooth Navarro-Frenk-White profile. In our most optimistic case, using the results of the Phoenix Project, we find that the derived limits reach below the thermal relic cross section of 3 Multiplication-Sign 10{sup -26} cm{sup 3} s{sup -1} for dark matter masses as large as 400 GeV, for the b b-bar annihilation channel. We discuss uncertainties due to the limited available data on the magnetic field structure of individual clusters. We also report the discovery of diffuse radio emission from the central 30-40 kpc regions of the groups M49 and NGC 4636.

Storm, Emma; Jeltema, Tesla E.; Profumo, Stefano [Department of Physics, University of California, 1156 High St., Santa Cruz, CA 95064 (United States); Rudnick, Lawrence [Minnesota Institute for Astrophysics, School of Physics and Astronomy, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States)

2013-05-10T23:59:59.000Z

412

LoCuSS: THE MASS DENSITY PROFILE OF MASSIVE GALAXY CLUSTERS AT z = 0.2 {sup ,}  

SciTech Connect (OSTI)

We present a stacked weak-lensing analysis of an approximately mass-selected sample of 50 galaxy clusters at 0.15 < z < 0.3, based on observations with Suprime-Cam on the Subaru Telescope. We develop a new method for selecting lensed background galaxies from which we estimate that our sample of red background galaxies suffers just 1% contamination. We detect the stacked tangential shear signal from the full sample of 50 clusters, based on this red sample of background galaxies, at a total signal-to-noise ratio of 32.7. The Navarro-Frenk-White model is an excellent fit to the data, yielding sub-10% statistical precision on mass and concentration: M{sub vir}=7.19{sup +0.53}{sub -0.50} Multiplication-Sign 10{sup 14} h{sup -1} M{sub sun}, c{sub vir}=5.41{sup +0.49}{sub -0.45} (c{sub 200}=4.22{sup +0.40}{sub -0.36}). Tests of a range of possible systematic errors, including shear calibration and stacking-related issues, indicate that they are subdominant to the statistical errors. The concentration parameter obtained from stacking our approximately mass-selected cluster sample is broadly in line with theoretical predictions. Moreover, the uncertainty on our measurement is comparable with the differences between the different predictions in the literature. Overall, our results highlight the potential for stacked weak-lensing methods to probe the mean mass density profile of cluster-scale dark matter halos with upcoming surveys, including Hyper-Suprime-Cam, Dark Energy Survey, and KIDS.

Okabe, Nobuhiro; Umetsu, Keiichi [Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), P. O. Box 23-141, Taipei 10617, Taiwan (China); Smith, Graham P. [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Takada, Masahiro [Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), University of Tokyo, Chiba 277-8582 (Japan); Futamase, Toshifumi, E-mail: okabe@asiaa.sinica.edu.tw, E-mail: gps@star.sr.bham.ac.uk [Astronomical Institute, Tohoku University, Aramaki, Aoba-ku, Sendai 980-8578 (Japan)

2013-06-01T23:59:59.000Z

413

Substructure in the Globular Cluster System of the Milky Way  

E-Print Network [OSTI]

The kinematical and spatial properties of the metal-rich globular clusters in the Galaxy ([Fe/H] > -0.8) indicates that these objects do not comprise a homogeneous population. Three subsystems are identified. The highest-mass clusters exhibit a very slow net rotation with a speed of v_rot = 24 km/s and v_rot/sigma = 0.3, indicative of a centrally condensed, spheroidal subsystem. Roughly half of the lower-mass clusters appear to be located in an elongated bar-like structure which passes through the Galactic Center, and has similar properties to the central stellar bar of the Milky Way. The remaining lower-mass clusters exhibit very rapid net rotation, with a rotation speed of v_rot = 164 km/s and v_rot/sigma = 6. These clusters are located in the Galactic plane, within a ring of 4 to 6 kpc radial distance from the Galactic Center. The highest-mass clusters may have formed during relatively advanced stages of the dissipative evolution of the inner Galactic halo. The lower-mass bar clusters may be associated with the formation of the Galactic stellar bar or bulge. The lower-mass ring clusters appear to be real disk objects. They may represent a stage in cluster formation that was intermediate between that of the halo globular clusters and the oldest extant open clusters.

A. Burkert; G. Smith

1996-10-23T23:59:59.000Z

414

The Properties of Young Clusters in M82  

E-Print Network [OSTI]

We present a detailed study of two luminous super star clusters in the starburst galaxy M82. Spectra, covering 3250-8790 A at a resolution of 1.6 A, were obtained at the 4.2 m William Herschel Telescope (WHT) for cluster F and the highly reddened cluster L. We compare the strengths of the observed Balmer absorption lines and the Balmer jump in the blue spectrum of F with theoretical model cluster spectra using the PEGASE spectral synthesis code to derive an age of 60+/-20 Myr. For cluster L, we find that the similarities in the strength of the Ca II triplet and overall spectral appearance with cluster F suggest a similar age. The brightness and compactness of cluster F make it an ideal candidate for determining its dynamical mass by measuring the velocity dispersion. We present the results of such an investigation based on echelle spectra at a resolution of 8 km/s obtained at the WHT from 5760-9140 A. By cross-correlating various wavelength regions in the spectrum of cluster F with cool giant and supergiant template stars, we derive a velocity dispersion and, by application of the virial theorem, determine a dynamical mass of 2 million solar masses. We compare our derived mass with those determined for other young super star clusters and discuss whether our derived parameters are consistent with cluster F being able to survive to become a globular cluster.

L. J. Smith; J. S. Gallagher

2000-01-31T23:59:59.000Z

415

Landscape Characterization and Representativeness Analysis for Understanding Sampling Network Coverage  

DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

Sampling networks rarely conform to spatial and temporal ideals, often comprised of network sampling points which are unevenly distributed and located in less than ideal locations due to access constraints, budget limitations, or political conflict. Quantifying the global, regional, and temporal representativeness of these networks by quantifying the coverage of network infrastructure highlights the capabilities and limitations of the data collected, facilitates upscaling and downscaling for modeling purposes, and improves the planning efforts for future infrastructure investment under current conditions and future modeled scenarios. The work presented here utilizes multivariate spatiotemporal clustering analysis and representativeness analysis for quantitative landscape characterization and assessment of the Fluxnet, RAINFOR, and ForestGEO networks. Results include ecoregions that highlight patterns of bioclimatic, topographic, and edaphic variables and quantitative representativeness maps of individual and combined networks.

Maddalena, Damian; Hoffman, Forrest; Kumar, Jitendra; Hargrove, William

416

Landscape Characterization and Representativeness Analysis for Understanding Sampling Network Coverage  

SciTech Connect (OSTI)

Sampling networks rarely conform to spatial and temporal ideals, often comprised of network sampling points which are unevenly distributed and located in less than ideal locations due to access constraints, budget limitations, or political conflict. Quantifying the global, regional, and temporal representativeness of these networks by quantifying the coverage of network infrastructure highlights the capabilities and limitations of the data collected, facilitates upscaling and downscaling for modeling purposes, and improves the planning efforts for future infrastructure investment under current conditions and future modeled scenarios. The work presented here utilizes multivariate spatiotemporal clustering analysis and representativeness analysis for quantitative landscape characterization and assessment of the Fluxnet, RAINFOR, and ForestGEO networks. Results include ecoregions that highlight patterns of bioclimatic, topographic, and edaphic variables and quantitative representativeness maps of individual and combined networks.

Maddalena, Damian; Hoffman, Forrest; Kumar, Jitendra; Hargrove, William

2014-08-01T23:59:59.000Z

417

Clusters and Superclusters in the Sloan and Las Campanas Surveys  

E-Print Network [OSTI]

We generate the 2-dimensional high-resolution density field of galaxies of the Early Data Release of the Sloan Digital Sky Survey and the Las Campanas Redshift Survey with a smoothing length 0.8 Mpc/h to extract clusters and groups of galaxies, and a low-resolution field with a smoothing length 10 Mpc/h to extract superclusters of galaxies. We investigate properties of density field clusters and superclusters and compare the properties of these clusters and superclusters with those of Abell clusters, and superclusters found on the basis of Abell clusters. We found that clusters in a high-density environment have a luminosity a factor of 5 - 10 higher than in a low-density environment. Clusters and superclusters in the Northern slice of SDSS are much richer than those in the Southern slice.

J. Einasto

2004-01-16T23:59:59.000Z

418

The Mean and Scatter of the Velocity Dispersion-Optical Richness Relation for MaxBCG Galaxy Clusters  

SciTech Connect (OSTI)

The distribution of galaxies in position and velocity around the centers of galaxy clusters encodes important information about cluster mass and structure. Using the maxBCG galaxy cluster catalog identified from imaging data obtained in the Sloan Digital Sky Survey, we study the BCG--galaxy velocity correlation function. By modeling its non-Gaussianity, we measure the mean and scatter in velocity dispersion at fixed richness. The mean velocity dispersion increases from 202 {+-} 10 km s{sup -1} for small groups to more than 854 {+-} 102 km s{sup -1} for large clusters. We show the scatter to be at most 40.5{+-}3.5%, declining to 14.9{+-}9.4% in the richest bins. We test our methods in the C4 cluster catalog, a spectroscopic cluster catalog produced from the Sloan Digital Sky Survey DR2 spectroscopic sample, and in mock galaxy catalogs constructed from N-body simulations. Our methods are robust, measuring the scatter to well within one-sigma of the true value, and the mean to within 10%, in the mock catalogs. By convolving the scatter in velocity dispersion at fixed richness with the observed richness space density function, we measure the velocity dispersion function of the maxBCG galaxy clusters. Although velocity dispersion and richness do not form a true mass--observable relation, the relationship between velocity dispersion and mass is theoretically well characterized and has low scatter. Thus our results provide a key link between theory and observations up to the velocity bias between dark matter and galaxies.

Becker, M.R.; McKay, T.A.; /Michigan U.; Koester, B.; /Chicago U., Astron. Astrophys. Ctr.; Wechsler, R.H.; /KIPAC, Menlo Park /SLAC /Stanford U., Phys. Dept.; Rozo, E.; /Ohio State U.; Evrard, A.; /Michigan U. /Michigan U., MCTP; Johnston, D.; /Caltech, JPL; Sheldon, E.; /New York U.; Annis, J.; /Fermilab; Lau, E.; /Chicago U., Astron. Astrophys. Ctr.; Nichol, R.; /Portsmouth U., ICG; Miller, C.; /Michigan U.

2007-06-05T23:59:59.000Z

419

ON THE DISCREPANCY BETWEEN THEORETICAL AND X-RAY CONCENTRATION-MASS RELATIONS FOR GALAXY CLUSTERS  

SciTech Connect (OSTI)

In the past 15 years, the concentration-mass relation has been investigated diffusely in theoretical studies. On the other hand, only recently has this relation been derived from X-ray observations. When that happened, the results caused a certain level of concern: the X-ray normalizations and slopes were found significantly dissimilar from those predicted by theory. We analyzed 52 galaxy clusters and groups, simulated with different descriptions of the physical processes that affect the baryonic component, with the purpose of determining whether these discrepancies are real or induced by biases in the computation of the concentration parameter or in the determination of the selection function of the cluster sample for which the analysis is carried out. In particular, we investigate how the simulated concentration-mass relation depends (1) on the radial range used to derive the concentration; (2) on the presence of baryons in the simulations, and on the effect of star formation and feedback from supernovae and active galactic nuclei (AGNs). Finally, we evaluate (3) how the results differ when adopting an X-ray approach for the analysis and (4) how the selection function based on X-ray luminosity can impact the results. All effects studied go in the direction of alleviating the discrepancy between observations and simulations, although with different significance: while the choice of the radial range to fit the profiles and the inclusion of the baryonic component play only a minor role, the X-ray approach to reconstruct the mass profiles and the selection of the cluster sample have a strong impact on the resulting concentration-mass relation. Extending the fit to the most central regions or reducing the fitting radius from the virial boundary to the typical X-ray external radius causes an increase of the normalization in radiative simulations by 5%-10%. In the second case, we measure a slope that is up to twice steeper than that derived by using the typical theoretical radial range. Radiative simulations including only supernova feedback produce 30% higher concentrations than the dark matter case. Such a difference is largely reduced when including the effect of AGN feedback. The concentration-mass relation derived from the X-ray synthetic catalog is significantly steeper due to the combination of several different effects, such as environment, dynamical state and dynamical history of the clusters, bias in mass and temperature measurements, and their dependence on the radius and on the mass of the system. Finally, selecting clusters according to their X-ray luminosity produces a net increase in both normalization and slope of the relation, since at fixed mass, the most luminous clusters are also the most concentrated.

Rasia, E. [Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, MI 48109 (United States); Borgani, S. [Dipartimento di Fisica dell' Universitŕ di Trieste, Sezione di Astronomia, via Tiepolo 11, I-34131 Trieste (Italy); Ettori, S.; Meneghetti, M. [INAF, Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127, Bologna (Italy); Mazzotta, P. [Dipartimento di Fisica, Universitŕ di Roma Tor Vergata, via della Ricerca Scientifica, I-00133, Roma (Italy)

2013-10-10T23:59:59.000Z

420

The Metallicity Dependence of the Stellar Luminosity and Initial Mass Functions: HST Observations of Open and Globular Clusters  

E-Print Network [OSTI]

Using HST and the WFPC2 we have acquired very deep V- and I-band photometry of stars in NGC 2420 and NGC 2477 to study cluster luminosity functions at approximately solar metallicity. We have determined these cluster luminosity functions down to $M_I$ = 10.5 (0.2 M$_{\\odot}$) and find that the luminosity function of NGC 2420 turns over at $M_I$ $\\approx$ 9.0, and possibly stops altogether by $M_I$ $\\approx$ 9.5. The luminosity function of NGC 2477 may flatten at $M_I$ $\\geq$ 9.5. We compare our open cluster luminosity functions to the solar neighborhood field star luminosity function of Kroupa, Tout \\& Gilmore (1993) and the four published HST globular cluster luminosity functions: $\\omega$ Cen (Elson {\\it et al.}\\ 1995), 47 Tuc (De Marchi \\& Paresce 1995b), M 15 (De Marchi \\& Paresce 1995a), and NGC 6397 (Paresce, De Marchi \\& Romaniello 1995). We find a smooth relation between the location of the luminosity function turn-over and the metallicity for all these low mass star samples which matches the expected $M_I$ versus [Fe/H] trend for a model star of $\\approx$ 0.27 M$_{\\odot}$ (Saumon 1995; Alexander {\\it et al.}\\ 1996). We interpret this smooth and systematic behavior in the cluster luminosity functions as strong evidence in favor of an invariant initial mass function and a metallicity-dependent mass-luminosity relation.

Ted von Hippel; Gerard Gilmore; Nial Tanvir; David Robinson; Derek H. P. Jones

1996-05-02T23:59:59.000Z

Note: This page contains sample records for the topic "four-stage cluster sampling" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

WIYN Open Cluster Study 1: Deep Photometry of NGC 188  

E-Print Network [OSTI]

We have employed precise V and I photometry of NGC 188 at WIYN to explore the cluster luminosity function (LF) and study the cluster white dwarfs (WDs). Our photometry is offset by V = 0.052 (fainter) from Sandage (1962) and Eggen & Sandage (1969). All published photometry for the past three decades have been based on these two calibrations, which are in error by 0.05 +- 0.01. We employ the Pinsonneault etal (1998) fiducial main sequence to derive a cluster distance modulus of 11.43 +- 0.08. We report observations that are >= 50% complete to V = 24.6 and find that the cluster central-field LF peaks at M_I ~ 3 to 4. This is unlike the solar neighborhood LF and unlike the LFs of dynamically unevolved portions of open and globular clusters, which rise continuously until M_I ~ 9.5. Although we find that >= 50% of the unresolved cluster objects are multiple systems, their presence cannot account for the shape of the NGC 188 LF. For theoretical reasons (Terlevich 1987; Vesperini & Heggie 1997) having to do with the survivability of NGC 188 we believe the cluster is highly dynamically evolved and that the missing low luminosity stars are either in the cluster outskirts or have left the cluster altogether. We identify nine candidate WDs, of which we expect three to six are bona fide cluster WDs. The luminosities of the faintest likely WD indicates an age (Bergeron, Wesemael, & Beauchamp 1995) of 1.14 +- 0.09 Gyrs. This is a lower limit to the cluster age and observations probing to V = 27 or 28 will be necessary to find the faintest cluster WDs and independently determine the cluster age. While our age limit is not surprising for this ~6 Gyr old cluster, our result demonstrates the value of the WD age technique with its very low internal errors. (abridged)

Ted von Hippel; Ata Sarajedini

1998-06-06T23:59:59.000Z

422

How does clustering depend on environment?  

E-Print Network [OSTI]

According to the current paradigm, galaxies form and reside in extended cold dark matter (CDM) halos and in turn are key tracers of cosmological structure. Understanding how different types of galaxies occupy halos of different masses is one of the major challenges facing extragalactic astrophysics. The observed galaxy properties depend on the environment surrounding the galaxy. Within the framework of most galaxy formation models the environmental dependence of the galaxy population is mainly due to the change of the halo mass function with large-scale environment. Such models make precise predictions for how galaxy clustering should depend on environment. We will illustrate this by presenting analytical models of dark matter and galaxy clustering along with results obtained from numerical simulations. With these results we can hope to obtain a better understanding of the link between galaxies and dark matter and thereby constrain galaxy formation models.

Ummi Abbas; Ravi K. Sheth

2004-05-13T23:59:59.000Z

423

The Georgi Algorithms of Jet Clustering  

E-Print Network [OSTI]

We reveal the direct link between the jet clustering algorithms recently proposed by Howard Georgi and parton shower kinematics, providing sound support from the theoretical side. The kinematics of this class of elegant algorithms is explored systematically and the jet function is generalized to $J^{(n)}_\\beta$ with a jet function index $n$. Based on three basic requirements that the result of jet clustering is process-independent, for softer subjets the inclusion cone is larger, and that the cone size cannot be too large in order to avoid mixing different jets, we derive constraints on the jet function index $n$ and the jet function parameter $\\beta$ which are closely related to phase space boundaries. Finally, we demonstrate that the jet algorithm is boost invariant.

Shao-Feng Ge

2014-08-30T23:59:59.000Z

424

Robustness of cluster synchronous patterns in small-world networks with inter-cluster co-competition balance  

SciTech Connect (OSTI)

All edges in the classical Watts and Strogatz's small-world network model are unweighted and cooperative (positive). By introducing competitive (negative) inter-cluster edges and assigning edge weights to mimic more realistic networks, this paper develops a modified model which possesses co-competitive weighted couplings and cluster structures while maintaining the common small-world network properties of small average shortest path lengths and large clustering coefficients. Based on theoretical analysis, it is proved that the new model with inter-cluster co-competition balance has an important dynamical property of robust cluster synchronous pattern formation. More precisely, clusters will neither merge nor split regardless of adding or deleting nodes and edges, under the condition of inter-cluster co-competition balance. Numerical simulations demonstrate the robustness of the model against the increase of the coupling strength and several topological variations.

Zhang, Jianbao [School of Science, Hangzhou Dianzi University, Hangzhou 310018 (China)] [School of Science, Hangzhou Dianzi University, Hangzhou 310018 (China); Ma, Zhongjun, E-mail: mzj1234402@163.com [School of Mathematics and Computing Science, Guilin University of Electronic Technology, Guilin 541004 (China)] [School of Mathematics and Computing Science, Guilin University of Electronic Technology, Guilin 541004 (China); Chen, Guanrong [Department of Electronic Engineering, City University of Hong Kong, Kowloon, Hong Kong (China)] [Department of Electronic Engineering, City University of Hong Kong, Kowloon, Hong Kong (China)

2014-06-15T23:59:59.000Z

425

Cluster Formation in Contracting Molecular Clouds  

E-Print Network [OSTI]

We explore, through a simplified, semi-analytic model, the formation of dense clusters containing massive stars. The parent cloud spawning the cluster is represented as an isothermal sphere. This sphere is in near force balance between self-gravity and turbulent pressure. Self-gravity, mediated by turbulent dissipation, drives slow contraction of the cloud, eventually leading to a sharp central spike in density and the onset of dynamical instability. We suggest that, in a real cloud, this transition marks the late and rapid production of massive stars. We also offer an empirical prescription, akin to the Schmidt law, for low-mass star formation in our contracting cloud. Applying this prescription to the Orion Nebula Cluster, we are able to reproduce the accelerating star formation previously inferred from the distribution of member stars in the HR diagram. The cloud turns about 10 percent of its mass into low-mass stars before becoming dynamically unstable. Over a cloud free-fall time, this figure drops to 1 percent, consistent with the overall star formation efficiency of molecular clouds in the Galaxy.

Eric Huff; Steven Stahler

2007-08-07T23:59:59.000Z

426

Oxygen abundance of open cluster dwarfs  

E-Print Network [OSTI]

We present oxygen abundances of dwarfs in the young open cluster IC 4665 deduced from the OI $\\lambda$7774 triplet lines and of dwarfs in the open cluster Pleiades derived from the [OI] $\\lambda$6300 forbidden line. Stellar parameters and oxygen abundances were derived using the spectroscopic synthesis tool SME (Spectroscopy Made Easy). We find a dramatic increase in the upper boundary of the OI triplet abundances with decreasing temperature in the dwarfs of IC 4665, consistent with the trend found by Schuler et al. in the open clusters Pleiades and M 34, and to a less extent in the cool dwarfs of Hyades (Schuler et al. 2006a) and UMa (King & Schuler 2005). By contrast, oxygen abundances derived from the [OI] $\\lambda$6300 forbidden line for stars in Pleiades and Hyades (Schuler et al. 2006b) are constant within the errors. Possible mechanisms that may lead a varying oxygen triplet line abundance are examined, including systematic errors in the stellar parameter determinations, the NLTE effects, surface activities and granulation. The age-related effects stellar surface activities (especially the chromospheric activities) are suggested by our analysis to blame for the large spreads of oxygen triplet line abundances.

Z. -X. Shen; X. -W. Liu; H. -W. Zhang; B. Jones; D. N. C. Lin

2007-03-30T23:59:59.000Z

427

MEASURING THE MASS DISTRIBUTION IN GALAXY CLUSTERS  

SciTech Connect (OSTI)

Cluster mass profiles are tests of models of structure formation. Only two current observational methods of determining the mass profile, gravitational lensing, and the caustic technique are independent of the assumption of dynamical equilibrium. Both techniques enable the determination of the extended mass profile at radii beyond the virial radius. For 19 clusters, we compare the mass profile based on the caustic technique with weak lensing measurements taken from the literature. This comparison offers a test of systematic issues in both techniques. Around the virial radius, the two methods of mass estimation agree to within {approx}30%, consistent with the expected errors in the individual techniques. At small radii, the caustic technique overestimates the mass as expected from numerical simulations. The ratio between the lensing profile and the caustic mass profile at these radii suggests that the weak lensing profiles are a good representation of the true mass profile. At radii larger than the virial radius, the extrapolated Navarro, Frenk and White fit to the lensing mass profile exceeds the caustic mass profile. Contamination of the lensing profile by unrelated structures within the lensing kernel may be an issue in some cases; we highlight the clusters MS0906+11 and A750, superposed along the line of sight, to illustrate the potential seriousness of contamination of the weak lensing signal by these unrelated structures.

Geller, Margaret J. [Smithsonian Astrophysical Observatory, 60 Garden St., Cambridge, MA 02138 (United States)] [Smithsonian Astrophysical Observatory, 60 Garden St., Cambridge, MA 02138 (United States); Diaferio, Antonaldo [Dipartimento di Fisica, Universita degli Studi di Torino, via P. Giuria 1, I-10125 Torino (Italy)] [Dipartimento di Fisica, Universita degli Studi di Torino, via P. Giuria 1, I-10125 Torino (Italy); Rines, Kenneth J. [Department of Physics and Astronomy, Western Washington University, Bellingham, WA 98225 (United States)] [Department of Physics and Astronomy, Western Washington University, Bellingham, WA 98225 (United States); Serra, Ana Laura, E-mail: mgeller@cfa.harvard.edu, E-mail: diaferio@ph.unito.it, E-mail: kenneth.rines@wwu.edu, E-mail: serra@to.infn.it [INAF, Osservatorio Astronomico di Torino, via Osservatorio 20, I-10025 Pino Torinese (Italy)

2013-02-10T23:59:59.000Z

428

Post-Award Deliverables Sample (Second Part of Sample Deliverables...  

Broader source: Energy.gov (indexed) [DOE]

Task Orders (IDIQ Attachment. J-4) Sample Statement of Work - Standard Service Offerings for Contractor-Identified Project ESPC TASK ORDER REQUEST FOR PROPOSAL (TO RFP) TEMPLATE...

429

Theoretical investigations of silver clusters and silver-ligand systems.  

SciTech Connect (OSTI)

Studies directed at understanding structural and electronic properties of silver clusters have been and remain the subject of an active theoretical [1-22] and experimental [23- 38] effort. One of the reasons is the (still) important role these systems play in the photographic process. Investigations of interactions of silver clusters with different atoms and molecules are motivated primarily by a possible utility of these clusters in catalytic processes. The important role of silver in the selective oxidation of ethylene into ethylene oxide, the feedstock for polyester production, is well-known [39]. Possible variations in chemical reactivity with the cluster size and understanding of the mechanisms of interactions with different ligands may lead to new and more efficient applications. Investigations of cluster-ligand systems also contribute a great deal to a better understanding of gas-surface interactions. Accordingly, theoretical studies of silver clusters and cluster-ligand systems [40-44] fall into two categories--those that use clusters as models for silver surfaces [40], and those that target clusters and cluster-ligand interactions as subjects in their own right [41-44]. The common goal of all these studies is to elucidate the nature of the interatomic interactions and bonding at the microscopic level and thereby arrive at a fundamental understanding and description of the various structural and electronic properties.

Jellinek, J.; Salian, U.; Srinivas, S.

1999-05-19T23:59:59.000Z

430

MOCK OBSERVATIONS OF BLUE STRAGGLERS IN GLOBULAR CLUSTER MODELS  

SciTech Connect (OSTI)

We created artificial color-magnitude diagrams of Monte Carlo dynamical models of globular clusters and then used observational methods to determine the number of blue stragglers in those clusters. We compared these blue stragglers to various cluster properties, mimicking work that has been done for blue stragglers in Milky Way globular clusters to determine the dominant formation mechanism(s) of this unusual stellar population. We find that a mass-based prescription for selecting blue stragglers will select approximately twice as many blue stragglers than a selection criterion that was developed for observations of real clusters. However, the two numbers of blue stragglers are well-correlated, so either selection criterion can be used to characterize the blue straggler population of a cluster. We confirm previous results that the simplified prescription for the evolution of a collision or merger product in the BSE code overestimates their lifetimes. We show that our model blue stragglers follow similar trends with cluster properties (core mass, binary fraction, total mass, collision rate) as the true Milky Way blue stragglers as long as we restrict ourselves to model clusters with an initial binary fraction higher than 5%. We also show that, in contrast to earlier work, the number of blue stragglers in the cluster core does have a weak dependence on the collisional parameter ? in both our models and in Milky Way globular clusters.

Sills, Alison; Glebbeek, Evert [Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Chatterjee, Sourav [Department of Astronomy, University of Florida, Gainesville, FL 32611 (United States); Rasio, Frederic A., E-mail: asills@mcmaster.ca, E-mail: e.glebbeek@astro.ru.nl, E-mail: s.chatterjee@astro.ufl.edu, E-mail: rasio@northwestern.edu [Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States)

2013-11-10T23:59:59.000Z

431

Measuring Complementary Electronic Structure Properties of both Deposited and Gas Phase Clusters using STM, UPS, and PES: Size-Selected Clusters on Surfaces  

SciTech Connect (OSTI)

In this project, we studied size-selected cluster interactions with surfaces, with other clusters on surfaces, and with external stimuli. These studies focused on mobility as a function of cluster size, surface morphologies as a function of composition and coverage, ion-induced modification and reactivity of clusters as a function of composition, the structural evolution of cluster cuboids culminating in the characterization of theoretically-predicted “baby crystal” clusters, and unusual fractal pattern formation due to deposition.

Bowen, Kit H.

2014-03-05T23:59:59.000Z

432

Aerosol cluster impact and break-up : II. Atomic and Cluster Scale Models.  

SciTech Connect (OSTI)

Understanding the interaction of aerosol particle clusters/flocs with surfaces is an area of interest for a number of processes in chemical, pharmaceutical, and powder manufacturing as well as in steam-tube rupture in nuclear power plants. Developing predictive capabilities for these applications involves coupled phenomena on multiple length and timescales from the process macroscopic scale ({approx}1m) to the multi-cluster interaction scale (1mm-0.1m) to the single cluster scale ({approx}1000 - 10000 particles) to the particle scale (10nm-10{micro}m) interactions, and on down to the sub-particle, atomic scale interactions. The focus of this report is on the single cluster scale; although work directed toward developing better models of particle-particle interactions by considering sub-particle scale interactions and phenomena is also described. In particular, results of mesoscale (i.e., particle to single cluster scale) discrete element method (DEM) simulations for aerosol cluster impact with rigid walls are presented. The particle-particle interaction model is based on JKR adhesion theory and is implemented as an enhancement to the granular package in the LAMMPS code. The theory behind the model is outlined and preliminary results are shown. Additionally, as mentioned, results from atomistic classical molecular dynamics simulations are also described as a means of developing higher fidelity models of particle-particle interactions. Ultimately, the results from these and other studies at various scales must be collated to provide systems level models with accurate 'sub-grid' information for design, analysis and control of the underlying systems processes.

Lechman, Jeremy B.; Takato, Yoichi (State University of New York at Buffalo, Buffalo, NY)

2010-09-01T23:59:59.000Z

433

Acceptance sampling using judgmental and randomly selected samples  

SciTech Connect (OSTI)

We present a Bayesian model for acceptance sampling where the population consists of two groups, each with different levels of risk of containing unacceptable items. Expert opinion, or judgment, may be required to distinguish between the high and low-risk groups. Hence, high-risk items are likely to be identifed (and sampled) using expert judgment, while the remaining low-risk items are sampled randomly. We focus on the situation where all observed samples must be acceptable. Consequently, the objective of the statistical inference is to quantify the probability that a large percentage of the unsampled items in the population are also acceptable. We demonstrate that traditional (frequentist) acceptance sampling and simpler Bayesian formulations of the problem are essentially special cases of the proposed model. We explore the properties of the model in detail, and discuss the conditions necessary to ensure that required samples sizes are non-decreasing function of the population size. The method is applicable to a variety of acceptance sampling problems, and, in particular, to environmental sampling where the objective is to demonstrate the safety of reoccupying a remediated facility that has been contaminated with a lethal agent.

Sego, Landon H.; Shulman, Stanley A.; Anderson, Kevin K.; Wilson, John E.; Pulsipher, Brent A.; Sieber, W. Karl

2010-09-01T23:59:59.000Z

434

Adaptive Sampling for Environmental Robotics  

E-Print Network [OSTI]

186, 2003. S. Thrun, “Robotics Mapping: A survey”, Exploringtechnique to environmental robotics applications includingSampling for Environmental Robotics Mohammad Rahimi †,‡‡ ,

Mohammad Rahimi; Richard Pon; Deborah Estrin; William J. Kaiser; Mani Srivastava; Gaurav S. Sukhatme

2003-01-01T23:59:59.000Z

435

Sample Residential Program Term Sheet  

Broader source: Energy.gov [DOE]

A sample for defining and elaborating on the specifics of a clean energy loan program. Author: U.S. Department of Energy

436

Homeowner Soil Sample Information Form  

E-Print Network [OSTI]

Homeowners should submit this form with their soil samples when requesting a soil test from the Texas A&M Soil Testing Laboratory....

Provin, Tony

2007-04-11T23:59:59.000Z

437

MEASURING THE ULTIMATE HALO MASS OF GALAXY CLUSTERS: REDSHIFTS AND MASS PROFILES FROM THE HECTOSPEC CLUSTER SURVEY (HeCS)  

SciTech Connect (OSTI)

The infall regions of galaxy clusters represent the largest gravitationally bound structures in a {Lambda}CDM universe. Measuring cluster mass profiles into the infall regions provides an estimate of the ultimate mass of these halos. We use the caustic technique to measure cluster mass profiles from galaxy redshifts obtained with the Hectospec Cluster Survey (HeCS), an extensive spectroscopic survey of galaxy clusters with MMT/Hectospec. We survey 58 clusters selected by X-ray flux at 0.1 < z < 0.3. The survey includes 22,680 unique MMT/Hectospec redshifts for individual galaxies; 10,145 of these galaxies are cluster members. For each cluster, we acquired high signal-to-noise spectra for {approx}200 cluster members and a comparable number of foreground/background galaxies. The cluster members trace out infall patterns around the clusters. The members define a very narrow red sequence. We demonstrate that the determination of velocity dispersion is insensitive to the inclusion of bluer members (a small fraction of the cluster population). We apply the caustic technique to define membership and estimate the mass profiles to large radii. The ultimate halo mass of clusters (the mass that remains bound in the far future of a {Lambda}CDM universe) is on average (1.99 {+-} 0.11)M{sub 200}, a new observational cosmological test in essential agreement with simulations. Summed profiles binned in M{sub 200} and in L{sub X} demonstrate that the predicted Navarro-Frenk-White form of the density profile is a remarkably good representation of the data in agreement with weak lensing results extending to large radius. The concentration of these summed profiles is also consistent with theoretical predictions.

Rines, Kenneth [Department of Physics and Astronomy, Western Washington University, Bellingham, WA 98225 (United States)] [Department of Physics and Astronomy, Western Washington University, Bellingham, WA 98225 (United States); Geller, Margaret J.; Kurtz, Michael J. [Smithsonian Astrophysical Observatory, 60 Garden Street, MS 20, Cambridge, MA 02138 (United States)] [Smithsonian Astrophysical Observatory, 60 Garden Street, MS 20, Cambridge, MA 02138 (United States); Diaferio, Antonaldo, E-mail: kenneth.rines@wwu.edu, E-mail: diaferio@ph.unito.it [Dipartimento di Fisica, Universita di Torino, Torino (Italy)] [Dipartimento di Fisica, Universita di Torino, Torino (Italy)

2013-04-10T23:59:59.000Z

438

Experimental studies of the chemistry of metal clusters  

SciTech Connect (OSTI)

The procedures for studying chemical reactions of metal clusters in a continuous-flow reactor are described, and examples of such studies are given. Experiments to be discussed include kinetics and thermodynamics measurements, and determination of the composition of clusters saturated with various adsorbate reagents. Specific systems to be covered include the reaction of iron clusters with ammonia and with hydrogen, the reaction of nickel clusters with hydrogen and with ammonia, and the reaction of platinum clusters with ethylene. The last two reactions are characterized by complex, multi-step processes that lead to adsorbate decomposition and hydrogen desorption from the clusters. Methods for probing these processes will be discussed. 26 refs., 8 figs.

Parks, E.K.; Riley, S.J.

1988-01-01T23:59:59.000Z

439

Collisional Hardening of Compact Binaries in Globular Clusters  

E-Print Network [OSTI]

We consider essential mechanisms for orbit-shrinkage or "hardening" of compact binaries in globular clusters to the point of Roche-lobe contact and X-ray emission phase, focussing on the process of collisional hardening due to encounters between binaries and single stars in the cluster core. The interplay between this kind of hardening and that due to emission of gravitational radiation produces a characteristic scaling of the orbit-shrinkage time with the single-star binary encounter rate $\\gamma$ in the cluster which we introduce, clarify, and explore. We investigate possible effects of this scaling on populations of X-ray binaries in globular clusters within the framework of a simple "toy" scheme for describing the evolution of pre-X-ray binaries in globular clusters. We find the expected qualitative trends sufficiently supported by data on X-ray binaries in galactic globular clusters to encourage us toward a more quantitative study.

S. Banerjee; P. Ghosh

2006-09-29T23:59:59.000Z

440

Interaction between water cluster ions and mica surface  

SciTech Connect (OSTI)

Water cluster ion beams were irradiated on mica surfaces to investigate the interaction between molecular cluster ions and a mica surface. The contact angle of the mica surface increased with increasing dose of the water cluster ion beam, but the increase in the contact angle was smaller than that induced by an ethanol cluster ion beam. The surface roughness also increased with increasing dose of the water cluster ion beam, whereas the intensity of K 2p x-ray photoelectron spectroscopy peaks decreased with increasing dose of the water cluster ion beam. The decrease in the number of potassium atoms together with the increase in the surface roughness may be the causes of the increase in the contact angle.

Ryuto, Hiromichi, E-mail: ryuto@kuee.kyoto-u.ac.jp; Ohmura, Yuki; Nakagawa, Minoru; Takeuchi, Mitsuaki; Takaoka, Gikan H. [Photonics and Electronics Science and Engineering Center, Kyoto University, Nishikyo, Kyoto 615-8510 (Japan)

2014-03-15T23:59:59.000Z

Note: This page contains sample records for the topic "four-stage cluster sampling" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Experimental nanocalorimetry of protonated and deprotonated water clusters  

SciTech Connect (OSTI)

An experimental nanocalorimetric study of mass selected protonated (H{sub 2}O){sub n}H{sup +} and deprotonated (H{sub 2}O){sub n?1}OH{sup ?} water clusters is reported in the size range n = 20–118. Water cluster's heat capacities exhibit a change of slope at size dependent temperatures varying from 90 to 140 K, which is ascribed to phase or structural transition. For both anionic and cationic species, these transition temperatures strongly vary at small sizes, with higher amplitude for protonated than for deprotonated clusters, and change more smoothly above roughly n ? 35. There is a correlation between bonding energies and transition temperatures, which is split in two components for protonated clusters while only one component is observed for deprotonated clusters. These features are tentatively interpreted in terms of structural properties of water clusters.

Boulon, Julien; Braud, Isabelle; Zamith, Sébastien; Labastie, Pierre; L’Hermite, Jean-Marc [Université de Toulouse, UPS, Laboratoire Collisions Agrégats Réactivité, IRSAMC, F-31062 Toulouse (France) [Université de Toulouse, UPS, Laboratoire Collisions Agrégats Réactivité, IRSAMC, F-31062 Toulouse (France); CNRS, UMR 5589, F-31062 Toulouse (France)

2014-04-28T23:59:59.000Z

442

The luminosity -- halo-mass relation for brightest cluster galaxies  

E-Print Network [OSTI]

We examine the central-galaxy luminosity -- host-halo mass relation for 54 Brightest Group Galaxies (BGGs) and 92 Brightest Cluster Galaxies (BCGs) at z<0.1 and present the first measurement of this relation for a sample of known BCGs at 0.1

Sarah Brough; Warrick Couch; Chris Collins; Doug Burke; Bob Mann

2008-01-08T23:59:59.000Z

443

Defining And Characterizing Sample Representativeness For DWPF Melter Feed Samples  

SciTech Connect (OSTI)

Representative sampling is important throughout the Defense Waste Processing Facility (DWPF) process, and the demonstrated success of the DWPF process to achieve glass product quality over the past two decades is a direct result of the quality of information obtained from the process. The objective of this report was to present sampling methods that the Savannah River Site (SRS) used to qualify waste being dispositioned at the DWPF. The goal was to emphasize the methodology, not a list of outcomes from those studies. This methodology includes proven methods for taking representative samples, the use of controlled analytical methods, and data interpretation and reporting that considers the uncertainty of all error sources. Numerous sampling studies were conducted during the development of the DWPF process and still continue to be performed in order to evaluate options for process improvement. Study designs were based on use of statistical tools applicable to the determination of uncertainties associated with the data needs. Successful designs are apt to be repeated, so this report chose only to include prototypic case studies that typify the characteristics of frequently used designs. Case studies have been presented for studying in-tank homogeneity, evaluating the suitability of sampler systems, determining factors that affect mixing and sampling, comparing the final waste glass product chemical composition and durability to that of the glass pour stream sample and other samples from process vessels, and assessing the uniformity of the chemical composition in the waste glass product. Many of these studies efficiently addressed more than one of these areas of concern associated with demonstrating sample representativeness and provide examples of statistical tools in use for DWPF. The time when many of these designs were implemented was in an age when the sampling ideas of Pierre Gy were not as widespread as they are today. Nonetheless, the engineers and statisticians used carefully thought out designs that systematically and economically provided plans for data collection from the DWPF process. Key shared features of the sampling designs used at DWPF and the Gy sampling methodology were the specification of a standard for sample representativeness, an investigation that produced data from the process to study the sampling function, and a decision framework used to assess whether the specification was met based on the data. Without going into detail with regard to the seven errors identified by Pierre Gy, as excellent summaries are readily available such as Pitard [1989] and Smith [2001], SRS engineers understood, for example, that samplers can be biased (Gy?s extraction error), and developed plans to mitigate those biases. Experiments that compared installed samplers with more representative samples obtained directly from the tank may not have resulted in systematically partitioning sampling errors into the now well-known error categories of Gy, but did provide overall information on the suitability of sampling systems. Most of the designs in this report are related to the DWPF vessels, not the large SRS Tank Farm tanks. Samples from the DWPF Slurry Mix Evaporator (SME), which contains the feed to the DWPF melter, are characterized using standardized analytical methods with known uncertainty. The analytical error is combined with the established error from sampling and processing in DWPF to determine the melter feed composition. This composition is used with the known uncertainty of the models in the Product Composition Control System (PCCS) to ensure that the wasteform that is produced is comfortably within the acceptable processing and product performance region. Having the advantage of many years of processing that meets the waste glass product acceptance criteria, the DWPF process has provided a considerable amount of data about itself in addition to the data from many special studies. Demonstrating representative sampling directly from the large Tank Farm tanks is a difficult, if not unsolvable enterprise due to li

Shine, E. P.; Poirier, M. R.

2013-10-29T23:59:59.000Z

444

Low-Mass Cluster Galaxies: A Cornerstone of Galaxy Evolution  

E-Print Network [OSTI]

Low-mass cluster galaxies are the most common galaxy type in the universe and are at a cornerstone of our understanding of galaxy formation, cluster luminosity functions, dark matter and the formation of large scale structure. I describe in this summary recent observational results concerning the properties and likely origins of low-mass galaxies in clusters and the implications of these findings in broader galaxy formation issues.

Christopher J. Conselice

2002-12-10T23:59:59.000Z

445

Issues in the Formation of Globular Cluster Systems  

E-Print Network [OSTI]

Recent developments relevant to the formation of globular cluster systems in galaxies are discussed, including (1) The age distribution of the oldest Milky Way clusters, (2) Subgroups and possible accretion and merger remnants in the Galactic halo, (3) Key features of globular cluster systems in giant elliptical galaxies (metallicity distribution functions, luminosity distribution functions, specific frequencies). Processes contributing to the formation of giant ellipticals are summarized.

W. E. Harris

1998-01-21T23:59:59.000Z

446

THE INFRARED SPECTROSCOPY OF NEUTRAL POLYCYCLIC AROMATIC HYDROCARBON CLUSTERS  

SciTech Connect (OSTI)

The mid-infrared spectra of neutral homogeneous polycyclic aromatic hydrocarbon (PAH) clusters have been computed using density functional theory including an empirical correction for dispersion. The C-H out-of-plane bending modes are redshifted for all the clusters considered in this work. The magnitude of the redshift and the peak broadening are dependent on PAH size, shape, and on the PAH arrangement in the cluster.

Ricca, Alessandra [Carl Sagan Center, SETI Institute, 189 Bernardo Avenue, Suite 100, Mountain View, CA 94043 (United States); Bauschlicher, Charles W. Jr. [Entry Systems and Technology Division, Mail Stop 230-3, NASA Ames Research Center, Moffett Field, CA 94035 (United States); Allamandola, Louis J., E-mail: Alessandra.Ricca-1@nasa.gov, E-mail: Charles.W.Bauschlicher@nasa.gov [Space Science Division, Mail Stop 245-6, NASA Ames Research Center, Moffett Field, CA 94035 (United States)

2013-10-10T23:59:59.000Z

447

Lithium abundances in globular cluster giants: NGC 6218 (M12) and NGC 5904 (M5)  

E-Print Network [OSTI]

Convergent lines of evidence suggest that globular clusters host multiple stellar populations. It appears that they experience at least two episodes of star formation whereby a fraction of first-generation stars contribute astrated ejecta to form the second generation(s). To identify the polluting progenitors we require distinguishing chemical signatures such as that provided by lithium. Theoretical models predict that lithium can be synthesised in AGB stars, whereas no net Li production is expected from other candidates. It has been shown that in order to reproduce the abundance pattern found in M4, Li production must occur within the polluters, favouring the AGB scenario. Here we present Li and Al abundances for a large sample of RGB stars in M12 and M5. These clusters have a very similar metallicity, whilst demonstrating differences in several cluster properties. Our results indicate that the first-generation and second-generation stars share the same Li content in M12; we recover an abundance pattern simi...

D'Orazi, Valentina; Gratton, Raffaele G; Lattanzio, John C; Bragaglia, Angela; Carretta, Eugenio; Lucatello, Sara; Momany, Yazan

2014-01-01T23:59:59.000Z

448

Stromgren photometry of Galactic Globular Clusters. II Metallicity distribution of red giants in Omega Centauri  

E-Print Network [OSTI]

We present new intermediate-band Stroemgren photometry based on more than 300 u,v,b,y images of the Galactic globular cluster Omega Cen. Optical data were supplemented with new multiband near-infrared (NIR) photometry (350 J,H,K_s images). The final optical-NIR catalog covers a region of more than 20*20 arcmin squared across the cluster center. We use different optical-NIR color-color planes together with proper motion data available in the literature to identify candidate cluster red giant (RG) stars. By adopting different Stroemgren metallicity indices we estimate the photometric metallicity for ~4,000 RGs, the largest sample ever collected. The metallicity distributions show multiple peaks ([Fe/H]_phot=-1.73+/-0.08,-1.29+/-0.03,-1.05+/-0.02,-0.80+/-0.04,-0.42+/-0.12 and -0.07+/-0.08 dex) and a sharp cut-off in the metal-poor tail ([Fe/H]_phot-1.7 dex).

Calamida, A; Stetson, P B; Freyhammer, L M; Piersimoni, A M; Buonanno, R; Caputo, F; Cassisi, S; Castellani, M; Corsi, C E; Dall'Ora, M; Degl'Innocenti, S; Ferraro, I; Grundahl, F; Hilker, M; Monelli, M; Nonino, M; Patat, N; Pietrinferni, A; Moroni, P G Prada; Primas, F; Pulone, L; Richtler, T; Romaniello, M; Storm, J; Walker, A R

2009-01-01T23:59:59.000Z

449

Database Sampling with Functional Dependencies  

E-Print Network [OSTI]

Database Sampling with Functional Dependencies Jes´us Bisbal, Jane Grimson Department of Computer there is a need to prototype the database which the applications will use when in operation. A prototype database can be built by sampling data from an existing database. Including relevant semantic information when

Riera, Jesús Bisbal

450

THE SNAPSHOT HUBBLE U-BAND CLUSTER SURVEY (SHUCS). I. SURVEY DESCRIPTION AND FIRST APPLICATION TO THE MIXED STAR CLUSTER POPULATION OF NGC 4041  

SciTech Connect (OSTI)

We present the Snapshot Hubble U-band Cluster Survey (SHUCS), a project aimed at characterizing the star cluster populations of 10 nearby galaxies (d < 23 Mpc, half within Almost-Equal-To 12 Mpc) through new F336W (U-band equivalent) imaging from Wide Field Camera 3, and archival BVI-equivalent data with the Hubble Space Telescope. Completing the UBVI baseline reduces the age-extinction degeneracy of optical colors, thus enabling the measurement of reliable ages and masses for the thousands of clusters covered by our survey. The sample consists chiefly of face-on spiral galaxies at low inclination, in various degrees of isolation (isolated, in group, merging), and includes two active galactic nucleus hosts. This first paper outlines the survey itself, the observational datasets, the analysis methods, and presents a proof-of-concept study of the large-scale properties and star cluster population of NGC 4041, a massive SAbc galaxy at a distance of Almost-Equal-To 23 Mpc, and part of a small grouping of six giant members. We resolve two structural components with distinct stellar populations, a morphology more akin to merging and interacting systems. We also find strong evidence of a truncated, Schechter-type mass function, and a similarly segmented luminosity function. These results indicate that binning must erase much of the substructure present in the mass and luminosity functions, and might account for the conflicting reports on the intrinsic shape of these functions in the literature. We also note a tidal feature in the outskirts of the galaxy in Galaxy Evolution Explorer UV imaging, and follow it up with a comprehensive multi-wavelength study of NGC 4041 and its parent group. We deduce a minor merger as a likely cause of its segmented structure and the observed pattern of a radially decreasing star formation rate. We propose that combining the study of star cluster populations with broadband metrics is not only advantageous, but often easily achievable thorough archival datasets.

Konstantopoulos, I. S. [Australian Astronomical Observatory, P.O. Box 915, North Ryde NSW 1670 (Australia); Smith, L. J. [Space Telescope Science Institute and European Space Agency, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Adamo, A. [Max-Planck-Institut for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany); Silva-Villa, E. [Departement de Physique, de Genie Physique et d'Optique, and Centre de Recherche en Astrophysique du Quebec (CRAQ), Universite Laval, Quebec (Canada); Gallagher, J. S.; Ryon, J. E. [Department of Astronomy, University of Wisconsin-Madison, 5534 Sterling, 475 North Charter Street, Madison WI 53706 (United States); Bastian, N. [Astrophysics Research Institute, Liverpool John Moores University, Egerton Wharf, Birkenhead, CH41 1LD (United Kingdom); Westmoquette, M. S. [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei Muenchen (Germany); Zackrisson, E. [Department of Astronomy, Stockholm University, Oscar Klein Centre, AlbaNova, Stockholm SE-106 91 (Sweden); Larsen, S. S. [Department of Astrophysics/IMAPP, Radboud University Nijmegen, P.O. Box 9010, 6500 GL Nijmegen (Netherlands); Weisz, D. R. [Department of Astronomy, Box 351580, University of Washington, Seattle, WA 98195 (United States); Charlton, J. C., E-mail: iraklis@aao.gov.au [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States)

2013-05-15T23:59:59.000Z

451

ar cluster impact: Topics by E-print Network  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Impact of Civilian and Military Biology and Medicine Websites Summary: Uncovering the Stealth Cluster The Economic Impact of Civilian and Military Aerospace on South of...

452

Structure and Energetics of Nanometer Size Clusters of Sulfuric...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

in these clusters are determined mostly by electrostatic interactions. The thermodynamics of amine substitution is explored and compared to experimental thermodynamic and...

453

Active-Space Coupled-Cluster Methods Through Connected Quadruple...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Methods Through Connected Quadruple Excitations. Active-Space Coupled-Cluster Methods Through Connected Quadruple Excitations. Abstract: This abstract is currently not available...

454

On the efficiency of field star capture by star clusters  

E-Print Network [OSTI]

An exciting recent finding regarding scaling relations among globular clusters is the so-called 'blue tilt': clusters of the blue sub-population follow a trend of redder colour with increasing luminosity. In this paper we evaluate to which extent field star capture over a Hubble time may explain the 'blue tilt'. We perform collisional N-body simulations to quantify the amount of field star capture occuring over a Hubble time to star clusters with 10^3 to 10^6 stars. In the simulations we follow the orbits of field stars passing through a star cluster and calculate the energy change that the field stars experience due to gravitational interaction with cluster stars during one passage through the cluster. The capture condition is that their total energy after the passage is smaller than the gravitational potential at the cluster's tidal radius. By folding this with the fly-by rates of field stars with an assumed space density as in the solar neighbourhood and a range of velocity dispersions, we derive estimates on the mass fraction of captured field stars as a function of environment. We find that integrated over a Hubble time, the ratio between captured field stars and total number of clusters stars is very low (capture is not a probable mechanism for creating the colour-magnitude trend of metal-poor globular clusters.

Steffen Mieske; Holger Baumgardt

2007-09-10T23:59:59.000Z

455

Investigation of ${}^9$Be from nonlocalized clustering concept  

E-Print Network [OSTI]

The nonlocalized aspect of clustering, which is a new concept for self-conjugate nuclei, is extended for the investigation of the N{\

Mengjiao Lyu; Zhongzhou Ren; Bo Zhou; Yasuro Funaki; Hisashi Horiuchi; Gerd Röpke; Peter Schuck; Akihiro Tohsaki; Chang Xu; Taiichi Yamada

2014-12-31T23:59:59.000Z

456

Tungsten Cluster Migration on Nanoparticles: Minimum Energy Pathway...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Pathway and Migration Mechanism. Tungsten Cluster Migration on Nanoparticles: Minimum Energy Pathway and Migration Mechanism. Abstract: Transition state searches have been...

457

Using Cluster Road Mapping to Determine Strategic Clean Energy Direction  

Broader source: Energy.gov [DOE]

This document contains the transcript for the Using Cluster Roadmapping to Determine Your Strategic Clean Energy Direction webinar held on May 16, 2013.

458

Three-dimensional Modeling of Fracture Clusters in Geothermal...  

Broader source: Energy.gov (indexed) [DOE]

1 4.6.1 Three-dimensional Modeling of Fracture Clusters in Geothermal Reservoirs Presentation Number: 028 Investigator: Ghassemi, Ahmad (Texas A&M University) Objectives: To...

459

Computer System, Cluster and Networking Summer Institute (CSCNSI...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

CSCNSI Computer System, Cluster and Networking Summer Institute (CSCNSI) Emphasizes practical skill development. Contact Leader Francis J. Alexander (505) 665-4518 Email Deputy...

460

Aluminum Zintl anion moieties within sodium aluminum clusters  

SciTech Connect (OSTI)

Through a synergetic combination of anion photoelectron spectroscopy and density functional theory based calculations, we have established that aluminum moieties within selected sodium-aluminum clusters are Zintl anions. Sodium–aluminum cluster anions, Na{sub m}Al{sub n}{sup ?}, were generated in a pulsed arc discharge source. After mass selection, their photoelectron spectra were measured by a magnetic bottle, electron energy analyzer. Calculations on a select sub-set of stoichiometries provided geometric structures and full charge analyses for both cluster anions and their neutral cluster counterparts, as well as photodetachment transition energies (stick spectra), and fragment molecular orbital based correlation diagrams.

Wang, Haopeng; Zhang, Xinxing; Ko, Yeon Jae; Grubisic, Andrej; Li, Xiang; Ganteför, Gerd; Bowen, Kit H., E-mail: AKandalam@wcupa.edu, E-mail: kiran@mcneese.edu, E-mail: kbowen@jhu.edu [Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Schnöckel, Hansgeorg [Institute of Inorganic Chemistry, Karlsruhe Institute of Technology, 76128 Karlsruhe (Germany)] [Institute of Inorganic Chemistry, Karlsruhe Institute of Technology, 76128 Karlsruhe (Germany); Eichhorn, Bryan W. [Department of Chemistry, University of Maryland at College Park, College Park, Maryland 20742 (United States)] [Department of Chemistry, University of Maryland at College Park, College Park, Maryland 20742 (United States); Lee, Mal-Soon; Jena, P. [Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284 (United States)] [Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); Kandalam, Anil K., E-mail: AKandalam@wcupa.edu, E-mail: kiran@mcneese.edu, E-mail: kbowen@jhu.edu [Department of Physics, West Chester University of Pennsylvania, West Chester, Pennsylvania 19383 (United States); Kiran, Boggavarapu, E-mail: AKandalam@wcupa.edu, E-mail: kiran@mcneese.edu, E-mail: kbowen@jhu.edu [Department of Chemistry, McNeese State University, Lake Charles, Louisiana 70609 (United States)] [Department of Chemistry, McNeese State University, Lake Charles, Louisiana 70609 (United States)

2014-02-07T23:59:59.000Z