Sample records for natural abundance half-life

  1. Half-life and gamma abundance ratio measurements of Sm-153

    SciTech Connect (OSTI)

    Friese, Judah I.; Payne, Rosara F.; Greenwood, Lawrence R.; Soderquist, Chuck Z.; Garofoli, Stephanie J.

    2009-11-02T23:59:59.000Z

    The measurement of the decay of 153Sm was observed by gamma spectrometry, liquid scintillation counting and gas proportional counting in an attempt to confirm the half life and gamma abundance ratios for this isotope. Recent changes in the published nuclear decay data indicate that historical literature values may be biased. The 153Sm was made by the neutron activation of ultrapure isotopically enriched 152Sm to create 153Sm. The decay measurements were made over a three week period and no other isotopes were detected during this time. The gamma abundance ratio for the 103 keV gamma was measured to be (27.9%) which is 4% lower than the published data. In addition, the half life was 1.9308 days, which is 0.34% lower than the published data.

  2. nature biotechnology volume 27 number 12 december 2009 1 half-life for indications when an extended residence time in the cir-

    E-Print Network [OSTI]

    Cai, Long

    and can complicate tight control over plasma Focus on synthetic biology This issue of Nature Biotechnology

  3. Half-life Limit of 19Mg

    E-Print Network [OSTI]

    N. Frank; T. Baumann; D. Bazin; R. R. C. Clement; M. W. Cooper; P. Heckman; W. A. Peters; A. Stolz; M. Thoennessen; M. S. Wallace

    2003-10-17T23:59:59.000Z

    A search for 19Mg was performed using projectile fragmentation of a 150 MeV/nucleon 36Ar beam. No events of 19Mg were observed. From the time-of-flight through the fragment separator an upper limit of 22 ns for the half-life of 19Mg was established.

  4. Half-Life of $^{14}$O

    E-Print Network [OSTI]

    J. T. Burke; P. A. Vetter; S. J. Freedman; B. K. Fujikawa; W. T. Winter

    2006-07-27T23:59:59.000Z

    We have measured the half-life of $^{14}$O, a superallowed $(0^{+} \\to 0^{+})$ $\\beta$ decay isotope. The $^{14}$O was produced by the $^{12}$C($^{3}$He,n)$^{14}$O reaction using a carbon aerogel target. A low-energy ion beam of $^{14}$O was mass separated and implanted in a thin beryllium foil. The beta particles were counted with plastic scintillator detectors. We find $t_{1/2} = 70.696\\pm 0.052$ s. This result is $1.5\\sigma$ higher than an average value from six earlier experiments, but agrees more closely with the most recent previous measurement.

  5. EFFECTIVE DOSIMETRIC HALF LIFE OF CESIUM 137 SOIL CONTAMINATION

    SciTech Connect (OSTI)

    Jannik, T; P Fledderman, P; Michael Paller, M

    2008-01-09T23:59:59.000Z

    In the early 1960s, an area of privately-owned swamp adjacent to the US Department of Energy's Savannah River Site (SRS), known as Creek Plantation, was contaminated by site operations. Studies conducted in 1974 estimated that approximately 925 GBq of {sup 137}Cs was deposited in the swamp. Subsequently, a series of surveys--composed of 52 monitoring locations--was initiated to characterize and trend the contaminated environment. The annual, potential, maximum doses to a hypothetical hunter were estimated by conservatively using the maximum {sup 137}Cs concentrations measured in the soil. The purpose of this report is to calculate an 'effective dosimetric' half-life for {sup 137}Cs in soil (based on the maximum concentrations) and compare it to the effective environmental half-life (based on the geometric mean concentrations).

  6. Half-life of {sup 151}Sm remeasured

    SciTech Connect (OSTI)

    He Ming; Shen Hongtao; Shi Guozhu; Yin Xinyi; Tian Weizhi; Jiang Shan [Department of Nuclear Physics, China Institute of Atomic Energy, Post Office Box 275-50, Beijing 102413 (China)

    2009-12-15T23:59:59.000Z

    The half-life of {sup 151}Sm was redetermined and compared with literature values. A {sup 151}Sm{sub 2}O{sub 3} sample was produced by exposing {sup 150}Sm{sub 2}O{sub 3} to the high neutron flux of the heavy water research reactor at the China Institute of Atomic Energy (CIAE). The number of atoms and the activity of {sup 151}Sm in the sample were measured by thermal ionization mass spectrometry (TIMS) and liquid scintillation counting (LSC), respectively. The half-life of {sup 151}Sm determined in this work is 96.6 yr, with a standard uncertainty of 2.4 yr based on a quadratic summation of the uncertainty components from the measurements of the number of atoms and the activity of {sup 151}Sm.

  7. Measurement of the Double Beta Decay Half-life of 130Te with the NEMO-3 Detector

    E-Print Network [OSTI]

    Arnold, R; Baker, J; Barabash, A S; Basharina-Freshville, A; Blondel, S; Bongrand, M; Broudin-Bay, G; Brudanin, V; Caffrey, A J; Chapon, A; Chauveau, E; Durand, D; Egorov, V; Flack, R; Garrido, X; Grozier, J; Guillon, B; Hubert, Ph; Jackson, C M; Jullian, S; Kauer, M; Klimenko, A; Kochetov, O; Konovalov, S I; Kovalenko, V; Lalanne, D; Lamhamdi, T; Lang, K; Liptak, Z; Lutter, G; Mamedov, F; Marquet, Ch; Martin-Albo, J; Mauger, F; Mott, J; Nachab, A; Nemchenok, I; Nguyen, C H; Nova, F; Novella, P; Ohsumi, H; Pahlka, R B; Perrot, F; Piquemal, F; Reyss, J L; Richards, B; Ricol, J S; Saakyan, R; Sarazin, X; Shitov, Yu; Simard, L; Šimkovic, F; Smolnikov, A; Söldner-Rembold, S; Štekl, I; Suhonen, J; Sutton, C S; Szklarz, G; Thomas, J; Timkin, V; Torre, S; Tretyak, V I; Umatov, V; Vála, L; Vanyushin, I; Vasiliev, V; Vorobel, V; Vylov, T; Zukauskas, A

    2011-01-01T23:59:59.000Z

    This Letter reports results from the NEMO-3 experiment based on an exposure of 1275 days with 661g of 130Te in the form of enriched and natural tellurium foils. With this data set the double beta decay rate of 130Te is found to be non-zero with a significance of 7.7 standard deviations and the half-life is measured to be T1/2 = (7.0 +/- 0.9(stat) +/- 1.1(syst)) x 10^{20} yr. This represents the most precise measurement of this half-life yet published and the first real-time observation of this decay.

  8. Can Environmental Factors Affect Half-Life in Beta-Decay? An Analysis

    E-Print Network [OSTI]

    Goodwin, John 1953-

    2013-01-16T23:59:59.000Z

    of the decaying radioactive nuclide, and even the distance between Earth and the Sun at the time of the half-life measurement. In this study we present evidence that the initial beliefs in the immutability of radioactive half-life (with the exception of a few...

  9. The 198Au beta-half-life in the metal Au revisited

    E-Print Network [OSTI]

    K. Fortak; R. Kunz; L. Gialanella; H. -W. Becker; J. Meijer; F. Strieder

    2010-09-10T23:59:59.000Z

    The half-life of the beta-decay of 198Au has been measured for room temperature and 12 K. The resulting values of T(RT) = 2.684 +- 0.004 d and T(12 K) = 2.687 +- 0.005 d agree well within statistical uncertainties. An evidence for a temperature dependence of the half-life was not observed.

  10. Measurement of the {sup 44}Ti half-life and its significance for supernova.

    SciTech Connect (OSTI)

    Ahmad, I.; Greene, J. P.; Kutschera, W.; Paul, M.

    1999-08-28T23:59:59.000Z

    In 1998, we reported the three-laboratory measurement of the {sup 44}Ti half-life which was determined relative to the well known value (5.2714 {+-} 0.0005 yr) of the {sup 60}Co half-life. We have continued the measurement at Argonne and Jerusalem and inclusion of data points for additional two years does not change our published value of 59.0 {+-} 0.6 yr.

  11. Measurement of the {sup 214}Po half-life by the DEVIS track setup

    SciTech Connect (OSTI)

    Belov, V. A.; Brakhman, E. V.; Zeldovich, O. Ya.; Karelin, A. K.; Kirichenko, V. V.; Kobyakin, A. S., E-mail: Alexander.Kobyakin@itep.ru; Kozodaeva, O. M.; Kuchenkov, A. V.; Tsvetkova, T. N. [Institute of Theoretical and Experimental Physics (Russian Federation)] [Institute of Theoretical and Experimental Physics (Russian Federation)

    2013-04-15T23:59:59.000Z

    Measurement of the {sup 214}Po half-life with the DEVIS track setup at the Institute of Theoretical and Experimental Physics (ITEP, Moscow) by means of a procedure based on determining lifetimes of individual nuclei is described. The value obtained for the {sup 214}Po half-life is 163.8 {+-} 3.0 Micro-Sign s. The possibility of reaching the accuracy of the measurements that is required for testing the statement that the decay of some nuclei has a nonexponential character and the source intensity necessary for this are discussed.

  12. Precise half-life measurement of the superallowed beta(+) emitter (26)Si

    E-Print Network [OSTI]

    Iacob, V. E.; Hardy, John C.; Banu, A.; Chen, L.; Golovko, V. V.; Goodwin, J.; Horvat, V.; Nica, N.; Park, H. I.; Trache, L.; Tribble, Robert E.

    2010-01-01T23:59:59.000Z

    We measured the half-life of the superallowed 0(+) -> 0(+) beta(+) emitter (26)Si to be 2245.3(7) ms. We used pure sources of (26)Si and employed a high-efficiency gas counter, whichwas sensitive to positrons from both this nuclide and its daughter...

  13. Precise half-life measurement of the superallowed beta(+) emitter (26)Si 

    E-Print Network [OSTI]

    Iacob, V. E.; Hardy, John C.; Banu, A.; Chen, L.; Golovko, V. V.; Goodwin, J.; Horvat, V.; Nica, N.; Park, H. I.; Trache, L.; Tribble, Robert E.

    2010-01-01T23:59:59.000Z

    We measured the half-life of the superallowed 0(+) -> 0(+) beta(+) emitter (26)Si to be 2245.3(7) ms. We used pure sources of (26)Si and employed a high-efficiency gas counter, whichwas sensitive to positrons from both this nuclide and its daughter...

  14. Precise half-life measurements for the superallowed beta(+) emitters Ar-34 and Cl-34

    E-Print Network [OSTI]

    Iacob, V. E.; Hardy, John C.; Brinkley, J. F.; Gagliardi, Carl A.; Mayes, V. E.; Nica, N.; Sanchez-Vega, M.; Tabacaru, G.; Trache, L.; Tribble, Robert E.

    2006-01-01T23:59:59.000Z

    PHYSICAL REVIEW C 74, 055502 (2006) Precise half-life measurements for the superallowed ?+ emitters 34Ar and 34Cl V. E. Iacob,* J. C. Hardy, J. F. Brinkley, C. A. Gagliardi, V. E. Mayes, N. Nica, M. Sanchez-Vega, G. Tabacaru, L. Trache, and R. E... 15, 17 (2002). [5] J. C. Hardy et al., Nucl. Phys. A223, 157 (1974). 055502-7 V. E. IACOB et al. PHYSICAL REVIEW C 74, 055502 (2006) [6] V. E. Iacob, E. Mayes, J. C. Hardy, R. G. Neilson, M. Sanchez- Vega, A. Azhari, C. A. Gagliardi, L. Trache...

  15. Precision Measurement of the 6He Half-Life and the Weak Axial Current in Nuclei

    E-Print Network [OSTI]

    A. Knecht; R. Hong; D. W. Zumwalt; B. G. Delbridge; A. Garcia; P. Mueller; H. E. Swanson; I. S. Towner; S. Utsuno; W. Williams; C. Wrede

    2012-03-23T23:59:59.000Z

    Studies of 6He beta decay along with tritium can play an important role in testing ab-initio nuclear wave-function calculations and may allow for fixing low-energy constants in effective field theories. Here, we present an improved determination of the 6He half-life to a relative precision of 3x10^(-4). Our value of 806.89 \\pm 0.11(stat)^{+0.23}_{-0.19}(syst) ms resolves a major discrepancy between previous measurements. Calculating the statistical rate function we determined the ft-value to be 803.04 ^{+0.26}_{-0.23} s. The extracted Gamow-Teller matrix element agrees within a few percent with ab-initio calculations.

  16. Conversion of experimental half-life to effective electron neutrino mass in 0nubetabeta decay

    SciTech Connect (OSTI)

    Smolnikov, Anatoly; Grabmayr, Peter [Joint Institute for Nuclear Research, Dubna, Russia, and Institute for Nuclear Research of the Russian Academy of Sciences, Moscow (Russian Federation); Kepler Center for Astro and Particle Physics, Eberhard Karls Universitaet Tuebingen (Germany)

    2010-02-15T23:59:59.000Z

    The Germanium Detector Array (GERDA) collaboration will be searching for neutrinoless double beta decay of {sup 76}Ge. As a result it will measure the half-life T{sub 1/2} of this rare process; or at least a new value for the lower limit for T{sub 1/2} will be derived. The sensitivity of the GERDA experiment on the effective electron neutrino mass depends on the theoretical value for the nuclear matrix element M and the kinematical phase space factor G.In this Brief Report we focus on existing difficulties in applying the dimensionless values of M calculated by various theoretical groups, which use different methods and parametrizations. The implicit radius dependencies in M and G are discussed. Resulting values of the neutrino mass are tabulated for various representative half-lives T{sub 1/2} representing the sensitivity of the various phases of the GERDA experiment.

  17. Ecological half-life of 137Cs in fish from a stream contaminated by nuclear reactor effluents

    SciTech Connect (OSTI)

    Peles, J. [Pennsylvania State University, McKeesport; BryanJr, A. [Savannah River Ecology Lab; Garten Jr, Charles T [ORNL; Ribble, D. [Trinity University; Smith, M. [Savannah River Ecology Lab

    2000-12-01T23:59:59.000Z

    Radiocesium ({sup 137}Cs) concentrations were determined during 1974, 1981 and 1998 for seven species of fish inhabiting a stream (Steel Creek) contaminated by effluents from a nuclear reactor to examine the decline of this radionuclide in a natural ecosystem. Median {sup 137}Cs concentrations were highest in Micropterus salmoides (largemouth bass) during each year of the investigation (1974 = 6.67 Bq g{sup -1} dry wt. of whole body; 1981 = 3.72 Bq g{sup -1}; 1998 = 0.35 Bq g{sup -1}), but no patterns of differences were observed among Aphredoderus sayanus (pirate perch), Esox americanus (redfin pickerel), Lepomis auritus (redbreast sunfish), L. gulosus (warmouth), L. punctatus (spotted sunfish), and Notropis cummingsae (dusky shiner). Results demonstrated a rapid decline in {sup 137}Cs within fish from Steel Creek during the 24-year period. For example, {sup 137}Cs concentrations in all fish species declined significantly among years, even after accounting for radioactive decay. The observed percent declines in {sup 137}Cs concentrations of individual species were 3-4 times greater between 1974 and 1981 compared to that expected by physical decay alone, and 2-3 times greater during 1981-1998. Ecological half-lives (EHLs) of {sup 137}Cs in fish ranged from 4.43 years in A. sayanus to 6.53 years in L. gulosus. The EHL for {sup 137}Cs in all fish species combined was 5.54 years. Current levels of {sup 137}Cs in fish from Steel Creek (1.16 Bq g{sup -1} dry wt. of whole body to below detection limits) indicate that the consumption of fish from this ecosystem poses little risk to humans and sensitive wildlife species. These results demonstrate the importance of incorporating the concept of ecological half-life into determinations concerning the length and severity of potential risks associated with radiocontaminants.

  18. Precise measurement of the 222Rn half-life: a probe to monitor the stability of radioactivity

    E-Print Network [OSTI]

    E. Bellotti; C. Broggini; G. Di Carlo; M. Laubenstein; R. Menegazzo

    2015-01-30T23:59:59.000Z

    We give the results of a study on the 222Rn decay we performed in the Gran Sasso Laboratory (LNGS) by detecting the gamma rays from the radon progeny. The motivation was to monitor the stability of radioactivity measuring several times per year the half-life of a short lifetime (days) source instead of measuring over a long period the activity of a long lifetime (tens or hundreds of years) source. In particular, we give the reason of the large periodical fluctuations in the count rate of the gamma rays due to radon inside a closed canister which has been described in literature and which has been attributed to a possible influence of a component in the solar irradiation affecting the nuclear decay rates. We then provide the result of four half-life measurements we performed underground at LNGS in the period from May 2014 to January 2015 with radon diffused into olive oil. Briefly, we did not measure any change of the 222Rn half-life with a 8*10^-5 precision. Finally, we provide the most precise value for the 222Rn half-life: 3.82146(16){stat}(4){syst} days.

  19. Measurement of the double beta decay half-life of Nd-150 and search for neutrinoless decay modes with the NEMO-3 detector

    E-Print Network [OSTI]

    Nasim Fatemi-Ghomi

    2009-05-11T23:59:59.000Z

    The half-life for two-neutrino double beta decay of Nd-150 has been measured with data taken by the NEMO 3 experiment at the Modane Underground Laboratory. The limits are also set on the half-life of different neutrinoless double beta decay of this isotope.

  20. EFFECTIVE HALF-LIFE OF CESIUM-137 IN VARIOUS ENVIRONMENTAL MEDIA AT THE SAVANNAH RIVER SITE

    SciTech Connect (OSTI)

    Jannik, T.; Paller, M.; Baker, R.

    2013-12-12T23:59:59.000Z

    During the operational history of the Savannah River Site (SRS), many different radionuclides have been released from site facilities into the SRS environment. However, only a relatively small number of pathways, most importantly {sup 137}Cs in fish and deer, have contributed significantly to doses and risks to the public. The “effective” half-lives (T{sub e}) of {sup 137}Cs (which include both physical decay and environmental dispersion) in Savannah River floodplain soil and vegetation and in fish and white-tailed deer from the SRS were estimated using long-term monitoring data. For 1974–2011, the T{sub e}s of {sup 137}Cs in Savannah River floodplain soil and vegetation were 17.0 years (95% CI = 14.2–19.9) and 13.4 years (95% CI = 10.8–16.0), respectively. These T{sub e}s were greater than in a previous study that used data collected only through 2005 as a likely result of changes in the flood regime of the Savannah River. Field analyses of {sup 137}Cs concentrations in deer collected during yearly controlled hunts at the SRS indicated an overall T{sub e} of 15.9 years (95% CI = 12.3–19.6) for 1965–2011; however, the T{sub e} for 1990–2011 was significantly shorter (11.8 years, 95% CI = 4.8–18.8) due to an increase in the rate of {sup 137}Cs removal. The shortest T{sub e}s were for fish in SRS streams and the Savannah River (3.5–9.0 years), where dilution and dispersal resulted in rapid {sup 137}Cs removal. Long-term data show that T{sub e}s are significantly shorter than the physical half-life of {sup 137}Cs in the SRS environment but that they can change over time. Therefore, it is desirable have a long period of record for calculating Tes and risky to extrapolate T{sub e}s beyond this period unless the processes governing {sup 137}Cs removal are clearly understood.

  1. Measurement of the Double-Beta Decay Half-life of {sup 136}Xe in KamLAND-Zen

    SciTech Connect (OSTI)

    KamLAND-Zen Collaboration; Gando, A.; Gando, Y.; Hanakago, H.; Ikeda, H.; Inoue, K.; Kato, R.; Koga, M.; Matsuda, S.; Mitsui, T.; Nakada, T.; Nakamura, K.; Obata, A.; Oki, A.; Ono, Y.; Shimizu, I.; Shirai, J.; Suzuki, A.; Takemoto, Y.; Tamae, K.; Ueshima, K.; Watanabe, H.; Xu, B. D.; Yamada, S.; Yoshida, H.; Kozlov, A.; Yoshida, S.; Banks, T. I.; Detwiler, J. A.; Freedman, S. J.; Fujikawa, B. K.; Han, K.; O'Donnell, T.; Berger, B. E.; Efremenko, Y.; Karwowski, H. J.; Markoff, D. M.; Tornow, W.; Enomoto, S.; Decowski, M. P.

    2012-01-23T23:59:59.000Z

    We present results from the KamLAND-Zen double-beta decay experiment based on an exposure of 77.6 days with 129 kg of {sup 136}Xe. The measured two-neutrino double-beta decay half-life of {sup 136}Xe is T{sup 2{nu}}{sub 1/2} = 2:38 {+-}#6; 0:02(stat)#6;{+-}0.14(syst)#2;x10{sup 21} yr, consistent with a recent measurement by EXO-200. We also obtain a lower limit for the neutrinoless double-beta decay half-life, T{sup 0{nu}}{sub 1/2} > 5.7 x#2; 10{sup 24} yr at 90% C.L.

  2. Precise measurement of the 222Rn half-life: a probe to monitor the stability of radioactivity

    E-Print Network [OSTI]

    Bellotti, E; Di Carlo, G; Laubenstein, M; Menegazzo, R

    2015-01-01T23:59:59.000Z

    We give the results of a study on the 222Rn decay we performed in the Gran Sasso Laboratory (LNGS) by detecting the gamma rays from the radon progeny. The motivation was to monitor the stability of radioactivity measuring several times per year the half-life of a short lifetime (days) source instead of measuring over a long period the activity of a long lifetime (tens or hundreds of years) source. In particular, we give the reason of the large periodical fluctuations in the count rate of the gamma rays due to radon inside a closed canister which has been described in literature and which has been attributed to a possible influence of a component in the solar irradiation affecting the nuclear decay rates. We then provide the result of four half-life measurements we performed underground at LNGS in the period from May 2014 to January 2015 with radon diffused into olive oil. Briefly, we did not measure any change of the 222Rn half-life with a 8*10^-5 precision. Finally, we provide the most precise value for the ...

  3. Neutrino Physics Neutrinos rarely interact despite their vast abundance in nature. To give a sense of

    E-Print Network [OSTI]

    Chapter 1 Neutrino Physics Neutrinos rarely interact despite their vast abundance in nature later in 1933, Enrico Fermi devised a theory for beta decays which 1 #12;Chapter 1: Neutrino Physics 2 indicated oscillations [6]. This chapter will describe neutrino physics and some of the experiments

  4. Plant Characteristics Associated with Natural Enemy Abundance at Michigan Native Plants

    E-Print Network [OSTI]

    Landis, Doug

    BEHAVIOR Plant Characteristics Associated with Natural Enemy Abundance at Michigan Native Plants A. K. FIEDLER1 AND D. A. LANDIS Department of Entomology, 204 Center for Integrated Plant Systems populations by providing them with plant resources such as pollen and nectar. Insects are known to respond

  5. Measurement of the half-life of 198Au in a non-metal: High-precision measurement shows no host-material dependence

    E-Print Network [OSTI]

    J. R. Goodwin; N. Nica; V. E. Iacob; A. Dibidad; J. C. Hardy

    2010-09-10T23:59:59.000Z

    We have measured the half-life of the beta decay of 198Au to be 2.6948(9) d, with the nuclide sited in an insulating environment. Comparing this result with the half-life we measured previously with a metallic environment, we find the half-lives in both environments to be the same within 0.04%, thus contradicting a prediction that screening from a "plasma" of quasi-free electrons in a metal increases the half-life by as much as 7%.

  6. Seasonal abundance and nature of damage of insects attacking cultivated sunflowers

    E-Print Network [OSTI]

    Phillips, Ronnie Lee

    1972-01-01T23:59:59.000Z

    , the vacuum sampling and whole-plant sampling methods, respectively, were used to collect injurious insect species associated with cultivated sunflowers. Popula- tion data proved that the whole-plant sampling method was more effective for obtaining insects...SEASONAL ABUNDANCE AND NATURE OF DAMAGE OF INSECTS ATTACKING CULTIVATED SUNFLOWERS A Thesis by Ronnie Lee Phillips Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER...

  7. Time-dependent extinction rate and species abundance in a tangled-nature model of biological evolution

    E-Print Network [OSTI]

    Christensen, Kim

    Time-dependent extinction rate and species abundance in a tangled-nature model of biological properties. The macrodynamics exhibit intermittent two-mode switching with a gradually decreasing extinction sense. The form of the species abundance curve compares well with observed func- tional forms. The model

  8. Measurement of the Double Beta Decay Half-life of 150-Nd and Search for Neutrinoless Decay Modes with the NEMO-3 Detector

    E-Print Network [OSTI]

    The NEMO Collaboration; J. Argyriades

    2009-08-18T23:59:59.000Z

    The half-life for double beta decay of 150-Nd has been measured by the NEMO-3 experiment at the Modane Underground Laboratory. Using 924.7 days of data recorded with 36.55 g of 150-Nd the half-life for 2nubb decay is measured to be T_1/2^2nu = (9.11+0.25_-0.22}(stat.) +- 0.63 (syst.)) x 10^18 years. The observed limit on the half-life for neutrinoless double beta decay is found to be T_1/2^{0nu} > 1.8 x 10^22 years at 90 % Confidence Level. This translates into a limit on the effective Majorana neutrino mass of neutrino}><4.0-6.3 eV if the nuclear deformation is taken into account. We also set limits on models involving Majoron emission, right-handed currents and transitions to excited states.

  9. Measurement of the two neutrino double beta decay half-life of Zr-96 and search for associated neutrinoless processes with the NEMO-3 detector

    E-Print Network [OSTI]

    Argyriades, J; Augier, C; Baker, J; Barabash, A S; Bongrand, M; Broudin-Bay, G; Brudanin, V B; Caffrey, A J; Chapon, A; Chauveau, E; Daraktchieva, Z; Durand, D; Egorov, V G; Fatemi-Ghomi, N; Flack, R; Freshville, A; Guillon, B; Hubert, Ph; Jullian, S; Kauer, M; King, S; Kochetov, O I; Konovalov, S I; Kovalenko, V E; Lalanne, D; Lang, K; Lemiere, Y; Lutter, G; Mamedov, F; Marquet, Ch; Martín-Albo, J; Mauger, F; Nachab, A; Nasteva, I; Nemchenok, I B; Nova, F; Novella, P; Ohsumi, H; Pahlka, R B; Perrot, F; Piquemal, F; Reyss, J L; Ricol, J S; Saakyan, R; Sarazin, X; Simard, L; Shitov, Yu A; Smolnikov, A A; Snow, S; Söldner-Rembold, S; Stekl, I; Sutton, C S; Szklarz, G; Thomas, J; Timkin, V V; Tretyak, V I; Tretyak, Vl I; Umatov, V I; Vàla, L; Vanyushin, I A; Vasiliev, V A; Vorobel, V; Vylov, Ts

    2009-01-01T23:59:59.000Z

    Using 1221 days of data from the NEMO-3 detector, the measurement of Zr-96 2vbb decay half-life is [2.35 +/- 0.14(stat) +/- 0.19(syst)] x 10^19 yr. Different characteristics of the final state electrons have been studied, such as the energy sum, individual electron energy, and angular distribution. The 2v nuclear matrix element is extracted using the measured 2vbb half-life and is 0.049 +/- 0.003. A 90% CL limit is set on the 0vbb decay half-life of > 9.2 x 10^21 yr corresponding to a limit on the effective Majorana neutrino mass < 7.2 - 19.5 eV. Limits on other mechanisms of 0vbb decay have also been set.

  10. Determination of the half-life of the ground state of {sup 229}Th by using {sup 232}U and {sup 233}U decay series

    SciTech Connect (OSTI)

    Kikunaga, H. [Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Nishina Center for Accelerator-Based Science, RIKEN, Wako, Saitama 351-0198 (Japan); Suzuki, T.; Nomura, M. [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8550 (Japan); Mitsugashira, T. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi 980-8577 (Japan); Shinohara, A. [Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan)

    2011-07-15T23:59:59.000Z

    The half-life of the ground state of {sup 229}Th ({sup 229}Th{sup g}) has become an important factor in nuclear technology, for example, in the geological disposal of nuclear spent fuel. However, the values reported in two previous studies are not in agreement. This study reevaluates the half-life of {sup 229}Th{sup g} by using a simple and reliable method. The {sup 232}U/{sup 233}U activity ratio of a {sup 232,233}U sample was measured by high-resolution {alpha}-particle spectrometry. Next, the {sup 228}Th/{sup 229}Th{sup g} activity ratio of the Th sample, which was grown from the {sup 232,233}U sample, was also measured. The half-life of {sup 229}Th{sup g} was calculated from these activity ratios, the growth time, and the half-lives of {sup 232}U, {sup 233}U, and {sup 228}Th. From the results of these five measurements, the half-life of {sup 229}Th{sup g} is determined to be 7932 {+-} 55 yr at a confidence level of 2{sigma}.

  11. Measurement of the double-{beta} decay half-life of {sup 150}Nd and search for neutrinoless decay modes with the NEMO-3 detector

    SciTech Connect (OSTI)

    Argyriades, J.; Augier, C.; Bongrand, M.; Jullian, S.; Lalanne, D.; Sarazin, X.; Simard, L.; Szklarz, G. [LAL, Universite Paris-Sud 11, CNRS/IN2P3, Orsay (France); Arnold, R. [IPHC, Universite de Strasbourg, CNRS/IN2P3, F-67037 Strasbourg (France); Baker, J.; Caffrey, A. J. [INL, Idaho Falls, Idaho 83415 (United States); Barabash, A. S.; Konovalov, S. I.; Umatov, V.; Vanyushin, I. [Institute of Theoretical and Experimental Physics, RU-117259 Moscow (Russian Federation); Basharina-Freshville, A.; Daraktchieva, Z.; Flack, R.; Kauer, M.; King, S. [University College London, WC1E 6BT London (United Kingdom)] (and others)

    2009-09-15T23:59:59.000Z

    The half-life for double-{beta} decay of {sup 150}Nd has been measured by the NEMO-3 experiment at the Modane Underground Laboratory. Using 924.7 days of data recorded with 36.55 g of {sup 150}Nd, we measured the half-life for 2{nu}{beta}{beta} decay to be T{sub 1/2}{sup 2{nu}}=(9.11{sub -0.22}{sup +0.25}(stat.){+-}0.63(syst.))x10{sup 18} yr. The observed limit on the half-life for neutrinoless double-{beta} decay is found to be T{sub 1/2}{sup 0{nu}}>1.8x10{sup 22} yr at 90% confidence level. This translates into a limit on the effective Majorana neutrino mass of <4.0-6.3 eV if the nuclear deformation is taken into account. We also set limits on models involving Majoron emission, right-handed currents, and transitions to excited states.

  12. NATURE MATERIALS | VOL 13 | MARCH 2014 | www.nature.com/naturematerials 233 hotovoltaic devices --which convert abundant, free solar

    E-Print Network [OSTI]

    - and downconversion11 , technologies that, like the multi-junction strategy, offer a roadmap beyond the Shockley dot photovoltaics Xinzheng Lan1,2 , Silvia Masala1,3 and Edward H. Sargent1 * The solar -- which convert abundant, free solar radiation into electric power -- are increasingly required to offer

  13. Roles of Naturally Occurring Bacteria in Controlling Iodine-129 Mobility in Subsurface Soils 

    E-Print Network [OSTI]

    Li, Hsiu-Ping

    2012-10-19T23:59:59.000Z

    129I is of major concern because of its biophilic nature, excessive inventory, long half-life (~16 million yrs), and high mobility in the natural environment that depends on its chemical speciation. Iodide (I-) has the ...

  14. Natural variations of /sup 13/C abundance in coal and bitumen as a tool to monitor co-processing

    SciTech Connect (OSTI)

    Muehlenbachs, K.; Steer, J.G. (Dept. of Geology, Univ. of Alberta, Edmonton Alberta, T6G 2E3 (CA)); Hogg, A. (Dept. of Chemistry, Univ. of Alberta, Edmonton Alberta T6G 2E3 (CA)); Ohuchi, T.; Beaulieu, G. (Coal Dept., Alberta Research Council, Devon, Alberta T0C 1E0 (CA))

    1988-06-01T23:59:59.000Z

    The use of coal to facilitate the generation of transportation grade fuel bitumen, heavy oil for petroleum resids is a topic of continuing research. In order to optimize the upgrading process one needs to know in what proportion each feedstock contributes to each product fraction. Conventional analytical methods are neither able to distinguish the contribution from either feedstock in the synthetic products, nor measure the subtle changes in product character in response to differing process conditions. The inherent difference in the /sup 13/C//sup 12/C ratio between most coals and bitumens can be utilized as an isotopic tracer to assess the efficacy of co-processing. For example Vesta coal and Athabasca bitumen have sufficiently distinct /sup 13/C//sup 12/C ratios that the measured /sup 13/C//sup 12/C of any product will accurately reflect the proportion of feed incorporated into the product. From the elemental analysis and the /sup 13/C//sup 12/C ratio of the feedstock and products one can calculate the amount of carbon derived from coal (CDC) in each product fraction. Analogously the amount of bitumen derived carbon (BDC) can also be independently calculated. In this study the natural variation in /sup 13/C concentration was utilized as an isotopic tracer to evaluate co-processing efficiency of a one litre stirred autoclave under differing process conditions. Process variables examined were coal concentration, several iron based catalysts (Fe/sub 2/O/sub 3/; Fe/sub 2/O/sub 3/ impregnated with TiO/sub 2/, SnO/sub 2/, or ZnO and a sludge obtained from a nickel refinery) and temperature.

  15. Natural variations of sup 13 C abundance in coal and bitumen as a tool to monitor coprocessing

    SciTech Connect (OSTI)

    Muehlenbachs, K.; Steer, J.G.; Hogg, A.; Ohuchi, T.; Beaulieu, G. (Univ. of Alberta, Edmonton (Canada))

    1988-01-01T23:59:59.000Z

    The use of coal to facilitate the generation of transportation grade fuel from bitumen, heavy oil or petroleum resids is a topic of continuing research. In order to optimize the upgrading process one needs to know in what proportion each feedstock contributes to each product fraction. Conventional analytical methods are neither able to distinguish the contribution from either feedstock in the synthetic products, nor measure the subtle changes in product character in response to differing process conditions. The inherent difference in the {sup 13}C/{sup 12}C ratio between most coals and bitumen can be utilized as an isotopic tracer to assess the efficacy of coprocessing. For example Vesta coal and Athabasca bitumen have sufficiently distinct {sup 13}C/{sup 12}C ratios that the measured {sup 13}C/{sup 12}C of any product will accurately reflect the proportion of feed incorporated into the product. From the elemental analysis and the {sup 13}C/{sup 12}C ratio of the feedstock and products one can calculate the amount of carbon derived from coal (CDC) in each product fraction. Analogously the amount of bitumen derived carbon (BDC) can also be independently calculated. In this study the natural variation in {sup 13}C concentration was utilized as an isotopic tracer to evaluate coprocessing efficiency of a one liter stirred autoclave under differing process conditions. Process variables examined were coal concentration, several iron based catalysts (Fe{sub 2}O{sub 3}; Fe{sub 2}O{sub 3} impregnated with TiO{sub 2}, SnO{sub 2}, or ZnO and a sludge obtained from a nickel refinery) and temperature.

  16. Production of 239 Pu from a natural Uranium disk and "hot" rock using a neutron howitzer

    E-Print Network [OSTI]

    Joseph Steiner; Aaron Anderson; Michael De Marco

    2008-05-23T23:59:59.000Z

    A neutron howitzer was used to produce 239Np from the targets of natural U and a hot rock. An intrinsic Germanium detector enabled the observations of the gamma rays in the decay of 239Np and a determination of its half life of 2.3 days. This shows that 239Pu had been produced in both targets

  17. Temporal effects of dredging and dredged material disposal on nekton in the offshore waters of Galveston, Texas, with notes on the natural histories of the most abundant taxa

    E-Print Network [OSTI]

    Henningsen, Brandt Flynn

    1977-01-01T23:59:59.000Z

    TEHPORAL 11FFEC S Ol DREDGING Ki'P3 DREDGED HATERIAL D. SPCSAL ON NEKTON IN THE OFF SHOPCE WATERS OI' GALVESTON, TEXAS, WITH NOTES ON THE NATLTAL HISTORIES OF THE HOST ABUNDANT 1'AXA A Thesis by BRMlDT FLYNN HENNINGSEN Submitted... to the Graduate College of Texas A&M University in partial fulfillment or the requirement for the degree of MASTER OF SCIENCE August 1977 Hajor Subject: Biology TEMPORAL EFFECTS OF DREDGING AND DREDGED MATERIAL DISPOSAL ON NEKTON IN THE OFFSHORE WATERS...

  18. Planetary nebulae: abundances and abundance gradients

    E-Print Network [OSTI]

    W. J. Maciel

    1999-11-05T23:59:59.000Z

    In this work, a review is given of some recent results and problems involved in the determination of chemical abundances of galactic planetary nebulae, particularly regarding disk and bulge objects.

  19. Helioseismology and Solar Abundances

    E-Print Network [OSTI]

    Sarbani Basu; H. M. Antia

    2007-11-28T23:59:59.000Z

    Helioseismology has allowed us to study the structure of the Sun in unprecedented detail. One of the triumphs of the theory of stellar evolution was that helioseismic studies had shown that the structure of solar models is very similar to that of the Sun. However, this agreement has been spoiled by recent revisions of the solar heavy-element abundances. Heavy element abundances determine the opacity of the stellar material and hence, are an important input to stellar model calculations. The models with the new, low abundances do not satisfy helioseismic constraints. We review here how heavy-element abundances affect solar models, how these models are tested with helioseismology, and the impact of the new abundances on standard solar models. We also discuss the attempts made to improve the agreement of the low-abundance models with the Sun and discuss how helioseismology is being used to determine the solar heavy-element abundance. A review of current literature shows that attempts to improve agreement between solar models with low heavy-element abundances and seismic inference have been unsuccessful so far. The low-metallicity models that have the least disagreement with seismic data require changing all input physics to stellar models beyond their acceptable ranges. Seismic determinations of the solar heavy-element abundance yield results that are consistent with the older, higher values of the solar abundance, and hence, no major changes to the inputs to solar models are required to make higher-metallicity solar models consistent with helioseismic data.

  20. The Solar Argon Abundance

    E-Print Network [OSTI]

    Katharina Lodders

    2007-10-24T23:59:59.000Z

    The solar argon abundance cannot be directly derived by spectroscopic observations of the solar photosphere. The solar Ar abundance is evaluated from solar wind measurements, nucleosynthetic arguments, observations of B stars, HII regions, planetary nebulae, and noble gas abundances measured in Jupiter's atmosphere. These data lead to a recommended argon abundance of N(Ar) = 91,200(+/-)23,700 (on a scale where Si = 10^6 atoms). The recommended abundance for the solar photosphere (on a scale where log N(H) = 12) is A(Ar)photo = 6.50(+/-)0.10, and taking element settling into account, the solar system (protosolar) abundance is A(Ar)solsys = 6.57(+/-)0.10.

  1. Element Abundances at High Redshifts

    E-Print Network [OSTI]

    Max Pettini

    1999-02-11T23:59:59.000Z

    I review measurements of element abundances in different components of the high redshift universe, including the Lyman alpha forest, damped Lyman alpha systems, and Lyman break galaxies. Although progress is being made in all three areas, recent work has also produced some surprises and shown that established ideas about the nature of the damped Lyman alpha systems in particular may be too simplistic. Overall, our knowledge of metal abundances at high z is still very sketchy. Most significantly, there seems to be an order of magnitude shortfall in the comoving density of metals which have been measured up to now compared with those produced by the star formation activity seen in Lyman break galaxies. At least some of the missing metals are likely to be in hot gas in galactic halos and proto-clusters.

  2. r-Process Abundance Signatures

    E-Print Network [OSTI]

    J. J. Cowan; C. Sneden

    2002-12-05T23:59:59.000Z

    Abundance observations indicate the presence of rapid-neutron capture (i.e., r-process) elements in old Galactic halo and globular cluster stars. These observations demonstrate that the earliest generations of stars in the Galaxy, responsible for neutron-capture synthesis and the progenitors of the halo stars, were rapidly evolving. Abundance comparisons among large numbers of stars provide clues about the nature of neutron-capture element synthesis both during the earliest times and throughout the history of the Galaxy. In particular, these comparisons suggest differences in the way the heavier (including Ba and above) and lighter neutron capture elements are synthesized in nature. Understanding these differences will help to identify the astrophysical site (or sites) of and conditions in the r-process. The abundance comparisons also demonstrate a large star-to-star scatter in the neutron-capture/iron ratios at low metallicities- which disappears with increasing [Fe/H]- and suggests an early, chemically unmixed and inhomogeneous Galaxy. The very recent neutron-capture element observations indicate that the early phases of Galactic nucleosynthesis, and the associated chemical evolution, are quite complex, with the yields from different (progenitor) mass-range stars contributing to different chemical mixes. Stellar abundance comparisons suggest a change from the r-process to the slow neutron capture (i.e., s-) process at higher metallicities (and later times) in the Galaxy. Finally, the detection of thorium and uranium in halo and globular cluster stars offers a promising, independent age-dating technique that can put lower limits on the age of the Galaxy and thus the Universe.

  3. The Primordial Helium Abundance

    E-Print Network [OSTI]

    Manuel Peimbert

    2008-11-18T23:59:59.000Z

    I present a brief review on the determination of the primordial helium abundance by unit mass, Yp. I discuss the importance of the primordial helium abundance in: (a) cosmology, (b) testing the standard big bang nucleosynthesis, (c) studying the physical conditions in H II regions, (d) providing the initial conditions for stellar evolution models, and (e) testing the galactic chemical evolution models.

  4. Detection of the Natural Alpha Decay of Tungsten

    E-Print Network [OSTI]

    C. Cozzini; G. Angloher; C. Bucci; F. von Feilitzsch; D. Hauff; S. Henry; Th. Jagemann; J. Jochum; H. Kraus; B. Majorovits; V. Mikhailik; J. Ninkovic; F. Petricca; W. Potzel; F. Proebst; Y. Ramachers; W. Rau; M. Razeti; W. Seidel; M. Stark; L. Stodolsky; A. J. B. Tolhurst; W. Westphal; H. Wulandari

    2004-10-26T23:59:59.000Z

    The natural alpha decay of 180W has been unambiguously detected for the first time. The alpha peak is found in a (gamma,beta and neutron)-free background spectrum. This has been achieved by the simultaneous measurement of phonon and light signals with the CRESST cryogenic detectors. A half-life of T1/2 = (1.8 +- 0.2) x 10^18 y and an energy release of Q = (2516.4 +- 1.1 (stat.) +- 1.2 (sys.)) keV have been measured. New limits are also set on the half-lives of the other naturally occurring tungsten isotopes.

  5. Constraining solar abundances using helioseismology

    E-Print Network [OSTI]

    Sarbani Basu; H. M. Antia

    2004-03-19T23:59:59.000Z

    Recent analyses of solar photospheric abundances suggest that the oxygen abundance in the solar atmosphere needs to be revised downwards. In this study we investigate the consequence of this revision on helioseismic analyses of the depth of the solar convection zone and the helium abundance in the solar envelope and find no significant effect. We also find that the revised abundances along with the current OPAL opacity tables are not consistent with seismic data. A significant upward revision of the opacity tables is required to make solar models with lower oxygen abundance consistent with seismic observations.

  6. Determining solar abundances using helioseismology

    E-Print Network [OSTI]

    H. M. Antia; Sarbani Basu

    2006-02-28T23:59:59.000Z

    The recent downward revision of solar photospheric abundances of Oxygen and other heavy elements has resulted in serious discrepancies between solar models and solar structure as determined through helioseismology. In this work we investigate the possibility of determining the solar heavy-element abundance without reference to spectroscopy by using helioseismic data. Using the dimensionless sound-speed derivative in the solar convection zone, we find that the heavy element abundance, Z, of 0.0172 +/- 0.002, which is closer to the older, higher value of the abundances.

  7. Gd Transition Probabilities and Abundances

    E-Print Network [OSTI]

    E. A. Den Hartog; J. E. Lawler; C. Sneden; J. J. Cowan

    2006-09-18T23:59:59.000Z

    Radiative lifetimes, accurate to +/- 5%, have been measured for 49 even-parity and 14 odd-parity levels of Gd II using laser-induced fluorescence. The lifetimes are combined with branching fractions measured using Fourier transform spectrometry to determine transition probabilities for 611 lines of Gd II. This work is the largest-scale laboratory study to date of Gd II transition probabilities and the first using a high performance Fourier transform spectrometer. This improved data set has been used to determine a new solar photospheric Gd abundance, log epsilon = 1.11 +/- 0.03. Revised Gd abundances have also been derived for the r-process-rich metal-poor giant stars CS 22892-052, BD+17 3248, and HD 115444. The resulting Gd/Eu abundance ratios are in very good agreement with the solar-system r-process ratio. We have employed the increasingly accurate stellar abundance determinations, resulting in large part from the more precise laboratory atomic data, to predict directly the Solar System r-process elemental abundances for Gd, Sm, Ho and Nd. Our analysis of the stellar data suggests slightly higher recommended values for the r-process contribution and total Solar System values, consistent with the photospheric determinations, for the elements for Gd, Sm, and Ho.

  8. Primordial Lithium Abundance in Catalyzed Big Bang Nucleosynthesis

    E-Print Network [OSTI]

    Chris Bird; Kristen Koopmans; Maxim Pospelov

    2008-05-19T23:59:59.000Z

    There exists a well known problem with the Li7+Be7 abundance predicted by standard big bang nucleosynthesis being larger than the value observed in population II stars. The catalysis of big bang nucleosynthesis by metastable, \\tau_X \\ge 10^3 sec, charged particles X^- is capable of suppressing the primordial Li7+Be7, abundance and making it consistent with the observations. We show that to produce the correct abundance, this mechanism of suppression places a requirement on the initial abundance of X^- at temperatures of 4\\times 10^8 K to be on the order of or larger than 0.02 per baryon, which is within the natural range of abundances in models with metastable electroweak-scale particles. The suppression of Li7+Be7, is triggered by the formation of (Be7X^-), compound nuclei, with fast depletion of their abundances by catalyzed proton reactions, and in some models by direct capture of X^- on Be7. The combination of Li7+Be7 and Li6 constraints favours the window of lifetimes, 1000s \\la tau_X \\leq 2000 s.

  9. Hf Transition Probabilities and Abundances

    E-Print Network [OSTI]

    J. E. Lawler; E. A. Den Hartog; Z. E. Labby; C. Sneden; J. J. Cowan; I. I. Ivans

    2006-11-01T23:59:59.000Z

    Radiative lifetimes from laser-induced fluorescence measurements, accurate to about +/- 5 percent, are reported for 41 odd-parity levels of Hf II. The lifetimes are combined with branching fractions measured using Fourier transform spectrometry to determine transition probabilities for 150 lines of Hf II. Approximately half of these new transition probabilities overlap with recent independent measurements using a similar approach. The two sets of measurements are found to be in good agreement for measurements in common. Our new laboratory data are applied to refine the hafnium photospheric solar abundance and to determine hafnium abundances in 10 metal-poor giant stars with enhanced r-process abundances. For the Sun we derive log epsilon (Hf) = 0.88 +/- 0.08 from four lines; the uncertainty is dominated by the weakness of the lines and their blending by other spectral features. Within the uncertainties of our analysis, the r-process-rich stars possess constant Hf/La and Hf/Eu abundance ratios, log epsilon (Hf/La) = -0.13 +/- 0.02 (sigma = 0.06) and log epsilon (Hf/Eu) = +0.04 +/- 0.02 (sigma = 0.06). The observed average stellar abundance ratio of Hf/Eu and La/Eu is larger than previous estimates of the solar system r-process-only value, suggesting a somewhat larger contribution from the r-process to the production of Hf and La. The newly determined Hf values could be employed as part of the chronometer pair, Th/Hf, to determine radioactive stellar ages.

  10. Nontoxic and Abundant Copper Zinc Tin Sulfide Nanocrystals for Potential High-Temperature Thermoelectric Energy Harvesting

    E-Print Network [OSTI]

    Chen, Yong P.

    and abundant copper zinc tin sulfide (CZTS) nanocrystals for potential thermoelectric applications. The CZTS sulfide (CZTS) as a nontoxic and abundant thermoelectric material and characterized its thermoelectric materials, the elements in the composition of CZTS are in extremely high abundancethe natural reserves

  11. Using automatically-triggered cameras to monitor and estimate bobcat abundance

    E-Print Network [OSTI]

    Heilbrun, Richard David

    2002-01-01T23:59:59.000Z

    triggered cameras as part of a mark-recapture study design. I tested the assumptions that bobcats were individually identifiable by their natural markings and that information obtained from camera surveys can contribute to abundance estimates from mark...

  12. Sm Transition Probabilities and Abundances

    E-Print Network [OSTI]

    J. E. Lawler; E. A. Den Hartog; C. Sneden; J. J. Cowan

    2005-10-19T23:59:59.000Z

    Radiative lifetimes, accurate to +/- 5%, have been measured for 212 odd-parity levels of Sm II using laser-induced fluorescence. The lifetimes are combined with branching fractions measured using Fourier-transform spectrometry to determine transition probabilities for more than 900 lines of Sm II. This work is the largest-scale laboratory study to date of Sm II transition probabilities using modern methods. This improved data set has been used to determine a new solar photospheric Sm abundance, log epsilon = 1.00 +/- 0.03, from 26 lines. The spectra of three very metal-poor, neutron-capture-rich stars also have been analyzed, employing between 55 and 72 Sm II lines per star. The abundance ratios of Sm relative to other rare earth elements in these stars are in agreement, and are consistent with ratios expected from rapid neutron-capture nucleosynthesis (the r-process).

  13. Electron Abundance in Protostellar Cores

    E-Print Network [OSTI]

    Paolo Padoan; Karen Willacy; William Langer; Mika Juvela

    2004-06-23T23:59:59.000Z

    The determination of the fractional electron abundance, Xe, in protostellar cores relies on observations of molecules, such as DCO+, H13CO+ and CO, and on chemical models to interpret their abundance. Studies of protostellar cores have revealed significant variations of Xe from core to core within a range 10^-8abundance from core to core as the combined effect of visual extinction and age variations. The range of electron abundances predicted by the models is relatively insenstive to density over 10^4 to 10^6 cm^{-3}.

  14. Abundant p-singular elements in finite classical groups

    E-Print Network [OSTI]

    Niemeyer, Alice C; Praeger, Cheryl E

    2012-01-01T23:59:59.000Z

    In 1995, Isaacs, Kantor and Spaltenstein proved that for a finite simple d-dimensional classical group G, and for any prime divisor p of |G| distinct from the characteristic, the proportion of p-singular elements (elements with order divisible by p) is at least c/d for some constant c. We define a new subfamily of p-singular elements, called p-abundant elements, which leave invariant certain "large" subspaces of the natural G-module. We find explicit upper and lower bounds for the proportion of p-abundant elements in G, and prove that it approaches a (positive) limiting value as d \\rightarrow \\infty. It turns out that the limiting proportion of p-abundant elements is at least a constant multiple of the lower bound for the proportion of all p-singular elements derived by Issacs, Kantor and Spaltenstein.

  15. The oxygen abundance distribution in M101

    E-Print Network [OSTI]

    L. S. Pilyugin

    2001-05-07T23:59:59.000Z

    The well-observed spiral galaxy M101 was considered. The radial distributions of oxygen abundances determined in three different ways (with the classic Te - method, with the R23 - method, and with the P -- method) were compared. It was found that the parameters (the central oxygen abundance and the gradient) of the radial O/H(P) abundance distribution are close to those of the O/H(Te) abundance distribution. The parameters of the O/H(R23) abundance distribution differ significantly from those of the O/H(Te) abundance distribution: the central O/H(R23) oxygen abundance is higher by around 0.4dex and the gradient is steeper by a factor of around 1.5 as compared to those values in the O/H(Te) abundance distribution. The dispersion in O/H(P) abundance at fixed radius is rather small, around 0.08 dex, and is equal to that in O/H(Te) abundance. The dispersion in O/H(R23) abundance at fixed radius is appreciably larger, around 0.16 dex, compared to that in O/H(Te) abundance. It has been shown that the extra dispersion in O/H(R23) abundances is an artifact and reflects scatter in excitation parameter P at fixed radius.

  16. Spectroscopic Study on the Beryllium Abundances of Red Giant Stars

    E-Print Network [OSTI]

    Takeda, Yoichi

    2014-01-01T23:59:59.000Z

    An extensive spectroscopic study was carried out for the beryllium abundances of 200 red giants (mostly of late G and early K type), which were determined from the near-UV Be II 3131.066 line based on high-dispersion spectra obtained by Subaru/HDS, with an aim of investigating the nature of surface Be contents in these evolved giants; e.g., dependence upon stellar parameters, degree of peculiarity along with its origin and build-up timing. We found that Be is considerably deficient (to widely different degree from star to star) in the photosphere of these evolved giants by ~1-3 dex (or more) compared to the initial abundance. While the resulting Be abundances (A(Be)) appear to weakly depend upon T_eff, log g, [Fe/H], M, age, and v_sin i, this may be attributed to the metallicity dependence of A(Be) coupled with the mutual correlation between these stellar parameters, since such tendencies almost disappear in the metallicity-scaled Be abundance ([Be/Fe]). By comparing the Be abundances (as well as their correl...

  17. Natural Abundance 43Ca NMR Spectroscopy of Tobermorite and Jennite...

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

    which has limited our ability to understand the structure of, for example, Ca–silicate hydrate (C–S–H). 43Ca nuclear magnetic resonance (NMR) spectroscopy has...

  18. Abundance measurements in stellar environments

    SciTech Connect (OSTI)

    Leone, F. [Università di Catania, Dipartimento di Fisica e Astronomia, Sezione Astrofisica, Via S. Sofia 78, 95123 Catania (Italy)

    2014-05-09T23:59:59.000Z

    Most of what we know about stars, and systems of stars, is derived from the analysis of their electromagnetic radiation. This lesson is an attempt to describe to Physicists, without any Astrophysical background, the framework to understand the present status of abundance determination in stellar environments and its limit. These notes are dedicated to the recently passed, November 21, 2013, Prof. Dimitri Mihalas who spent his life confuting the 19th century positivist philosopher Auguste Comte who stated that we shall not at all be able to determine the chemical composition of stars.

  19. Abundant Power | Open Energy Information

    Open Energy Info (EERE)

    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: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are being directedAnnual Siteof Energy 2,AUDITCaliforniaWeifangwiki HomeASN Power ProjectsAbraham HotAbundant Power

  20. Surface abundances of ON stars

    E-Print Network [OSTI]

    Martins, F; Palacios, A; Howarth, I; Georgy, C; Walborn, N R; Bouret, J -C; Barba, R

    2015-01-01T23:59:59.000Z

    Massive stars burn hydrogen through the CNO cycle during most of their evolution. When mixing is efficient, or when mass transfer in binary systems happens, chemically processed material is observed at the surface of O and B stars. ON stars show stronger lines of nitrogen than morphologically normal counterparts. Whether this corresponds to the presence of material processed through the CNO cycle or not is not known. Our goal is to answer this question. We perform a spectroscopic analysis of a sample of ON stars with atmosphere models. We determine the fundamental parameters as well as the He, C, N, and O surface abundances. We also measure the projected rotational velocities. We compare the properties of the ON stars to those of normal O stars. We show that ON stars are usually helium-rich. Their CNO surface abundances are fully consistent with predictions of nucleosynthesis. ON stars are more chemically evolved and rotate - on average - faster than normal O stars. Evolutionary models including rotation cann...

  1. Abundance Ratios in Early-Type Galaxies

    E-Print Network [OSTI]

    Reynier Peletier

    1999-04-21T23:59:59.000Z

    Although evidence is accumulating that abundance ratios in galaxies are often non-solar, they are far from understood. I resume the current evidence for non-solar abundance ratios, supplementing the recent review by Worthey (1998) with some new results. It appears that the Mg/Fe abundance ratio only depends on the mass of the galaxy, not on the formation time-scale. For massive galaxies [Mg/Fe] > 0, while small galaxies show solar abundance ratios. Information about abundances of other element is scarce, but new evidence is given that [Ca/Fe] is solar, or slightly lower than solar, contrary to what is expected for an alpha-element.

  2. Comparative analysis of spectra of the background of the proportional counter filled with Kr, enriched in Kr-78, and with Kr of natural content

    E-Print Network [OSTI]

    Yu. M. Gavriljuk; V. N. Gavrin; A. M. Gangapshev; V. V. Kazalov; V. V. Kuzminov; S. I. Panasenko; S. S. Ratkevich

    2007-11-16T23:59:59.000Z

    The results of the experiment searching for 2K-capture with large low-background proportional counter are presented. The comparison of spectra of the background of the proportional counter filled with Kr enriched in $^{78}$Kr (8400 hr) and with natural Kr (3039 hr) is given. A new limit on the half-life of $^{78}$Kr with regard to 2K-capture, T$_{1/2}\\geq2.0\\cdot10^{21}$ yrs (95% C.L.) has been obtained.

  3. Natural Gas as a Boiler Fuel of Choice in Texas

    E-Print Network [OSTI]

    Kmetz, W. J.

    Natural gas is abundant, clean burning, and cost competitive with other fuels. In addition to superior economic fundamentals, the expanded use of natural gas will be enhanced by political and industry leaders. Natural gas therefore will continue...

  4. Natural Gas as a Boiler Fuel of Choice in Texas 

    E-Print Network [OSTI]

    Kmetz, W. J.

    1992-01-01T23:59:59.000Z

    Natural gas is abundant, clean burning, and cost competitive with other fuels. In addition to superior economic fundamentals, the expanded use of natural gas will be enhanced by political and industry leaders. Natural gas therefore will continue...

  5. Stellar abundances of beryllium and CUBES

    E-Print Network [OSTI]

    Smiljanic, R

    2014-01-01T23:59:59.000Z

    Stellar abundances of beryllium are useful in different areas of astrophysics, including studies of the Galactic chemical evolution, of stellar evolution, and of the formation of globular clusters. Determining Be abundances in stars is, however, a challenging endeavor. The two Be II resonance lines useful for abundance analyses are in the near UV, a region strongly affected by atmospheric extinction. CUBES is a new spectrograph planned for the VLT that will be more sensitive than current instruments in the near UV spectral region. It will allow the observation of fainter stars, expanding the number of targets where Be abundances can be determined. Here, a brief review of stellar abundances of Be is presented together with a discussion of science cases for CUBES. In particular, preliminary simulations of CUBES spectra are presented, highlighting its possible impact in investigations of Be abundances of extremely metal-poor stars and of stars in globular clusters.

  6. Neutrino Physics and the Primordial Elemental Abundances

    E-Print Network [OSTI]

    Christian Y. Cardall; George M. Fuller

    1997-01-31T23:59:59.000Z

    Limits can be placed on nonstandard neutrino physics when big bang nucleosynthesis (BBN) calculations employing standard neutrino physics agree with the observationally inferred primordial abundances of deuterium (D), $^3$He, $^4$He, and $^7$Li. These constraints depend most sensitively on the abundances of D and $^4$He. New observational determinations of the primordial D and/or $^4$He abundances could force revisions in BBN constraints on nonstandard neutrino physics.

  7. The discrepancy between solar abundances and helioseismology

    E-Print Network [OSTI]

    H. M. Antia; Sarbani Basu

    2005-01-07T23:59:59.000Z

    There have been recent downward revisions of the solar photospheric abundances of Oxygen and other heavy elements. These revised abundances along with OPAL opacities are not consistent with seismic constraints. In this work we show that the recently released OP opacity tables cannot resolve this discrepancy either. While the revision in opacities does not seem to resolve this conflict, an upward revision of Neon abundance in solar photosphere offers a possible solution to this problem.

  8. On the oxygen abundance in our Galaxy

    E-Print Network [OSTI]

    L. S. Pilyugin; F. Ferrini; R. V. Shkvarun

    2003-02-03T23:59:59.000Z

    The compilation of published spectra of Galactic HII regions with available diagnostic [OIII]4363 line has been carried out. Our list contains 71 individual measurements of 13 HII regions in the range of galactocentric distances from 6.6 to 14.8 kpc. The oxygen abundances in all the HII regions were recomputed in the same way, using the classic Te - method. The oxygen abundance at the solar galactocentric distance traced by those HII regions is in agreement with the oxygen abundance in the interstellar medium in the solar vicinity derived with high precision from the interstellar absorption lines towards stars. The derived radial oxygen abundance distribution was compared with that for HII regions from the Shaver et al. (1983) sample which is the basis of many models for the chemical evolution of our Galaxy. It was found that the original Shaver et al.'s oxygen abundances are overestimated by 0.2-0.3 dex. Oxygen abundances in HII regions from the Shaver et al. sample have been redetermined with the recently suggested P - method. The radial distribution of oxygen abundances from the Shaver et al. sample redetermined with the P - method is in agreement with our radial distribution of (O/H)_Te abundances.

  9. On the solar nickel and oxygen abundances

    E-Print Network [OSTI]

    Pat Scott; Martin Asplund; Nicolas Grevesse; A. Jacques Sauval

    2009-01-27T23:59:59.000Z

    Determinations of the solar oxygen content relying on the neutral forbidden transition at 630 nm depend upon the nickel abundance, due to a Ni I blend. Here we rederive the solar nickel abundance, using the same ab initio 3D hydrodynamic model of the solar photosphere employed in the recent revision of the abundances of C, N, O and other elements. Using 17 weak, unblended lines of Ni I together with the most accurate atomic and observational data available we find log epsilon_Ni = 6.17 +/- 0.02 (statistical) +/- 0.05 (systematic), a downwards shift of 0.06 to 0.08 dex relative to previous 1D-based abundances. We investigate the implications of the new nickel abundance for studies of the solar oxygen abundance based on the [O I] 630 nm line in the quiet Sun. Furthermore, we demonstrate that the oxygen abundance implied by the recent sunspot spectropolarimetric study of Centeno & Socas-Navarro needs to be revised downwards from log epsilon_O = 8.86 +/- 0.07 to 8.71 +/- 0.10. This revision is based on the new nickel abundance, application of the best available gf-value for the 630 nm forbidden oxygen line, and a more transparent treatment of CO formation. Determinations of the solar oxygen content relying on forbidden lines now appear to converge around log epsilon_O = 8.7.

  10. Helioseismological Implications of Recent Solar Abundance Determinations

    E-Print Network [OSTI]

    John N. Bahcall; Sarbani Basu; Marc Pinsonneault; Aldo M. Serenelli

    2004-09-26T23:59:59.000Z

    We show that standard solar models are in good agreement with the helioseismologically determined sound speed and density as a function of solar radius, the depth of the convective zone, and the surface helium abundance, as long as those models do not incorporate the most recent heavy element abundance determinations. However, sophisticated new analyses of the solar atmosphere infer lower abundances of the lighter metals (like C, N, O, Ne, and Ar) than the previously widely used surface abundances. We show that solar models that include the lower heavy element abundances disagree with the solar profiles of sound speed and density as well as the depth of the convective zone and the helium abundance. The disagreements for models with the new abundances range from factors of several to many times the quoted uncertainties in the helioseismological measurements. The disagreements are at temperatures below what is required for solar interior fusion reactions and therefore do not significantly affect solar neutrino emission. If errors in thecalculated OPAL opacities are solely responsible for the disagreements, then the corrections in the opacity must extend from 2 times 10^6 K (R = 0.7R_Sun)to 5 times 10^6 K (R = 0.4 R_Sun), with opacity increases of order 10%.

  11. Natural Gas Supply in Denmark -A Model of Natural Gas Transmission and the

    E-Print Network [OSTI]

    the economic structure of the Danish natural gas market is formulated mathematically giving a descriptionNatural Gas Supply in Denmark - A Model of Natural Gas Transmission and the Liberalized Gas Market of the markets of natural gas and electricity and the existence of an abundance of de-centralized combined heat

  12. On the solar abundance of indium

    E-Print Network [OSTI]

    N. Vitas; I. Vince; M. Lugaro; O. Andriyenko; M. Gosic; R. J. Rutten

    2007-11-14T23:59:59.000Z

    The generally adopted value for the solar abundance of indium is over six times higher than the meteoritic value. We address this discrepancy through numerical synthesis of the 451.13 nm line on which all indium abundance studies are based, both for the quiet-sun and the sunspot umbra spectrum, employing standard atmosphere models and accounting for hyperfine structure and Zeeman splitting in detail. The results, as well as a re-appraisal of indium nucleosynthesis, suggest that the solar indium abundance is close to the meteoritic value, and that some unidentified ion line causes the 451.13 nm feature in the quiet-sun spectrum.

  13. The oxygen abundance deficiency in irregular galaxies

    E-Print Network [OSTI]

    L. S. Pilyugin; F. Ferrini

    2000-01-05T23:59:59.000Z

    The observed oxygen abundances in a number of irregular galaxies have been compared with predictions of the closed-box model of chemical and photometric evolution of galaxies. Oxygen is found to be deficient with respect to the predicted abundances. This is an indicator in favor of loss of heavy elements via galactic winds or/and of infall of low--abundance gas onto the galaxy. The oxygen abundance deficiency observed within the optical edge of a galaxy cannot be explained by mixing with the gas envelope observed outside the optical limit. We confirm the widespread idea that a significant part of the heavy elements is ejected by irregular galaxies in the intergalactic medium.

  14. Beryllium abundances in metal-poor stars

    E-Print Network [OSTI]

    K. F. Tan; J. R. Shi; G. Zhao

    2008-10-15T23:59:59.000Z

    We have determined beryllium abundances for 25 metal-poor stars based on the high resolution and high signal-to-noise ratio spectra from the VLT/UVES database. Our results confirm that Be abundances increase with Fe, supporting the global enrichment of Be in the Galaxy. Oxygen abundances based on [O I] forbidden line implies a linear relation with a slope close to one for the Be vs. O trend, which indicates that Be is probably produced in a primary process. Some strong evidences are found for the intrinsic dispersion of Be abundances at a given metallicity. The deviation of HD132475 and HD126681 from the general Be vs. Fe and Be vs. O trend favours the predictions of the superbubble model, though the possibility that such dispersion originates from the inhomogeneous enrichment in Fe and O of the protogalactic gas cannot be excluded.

  15. Oxygen abundance of open cluster dwarfs

    E-Print Network [OSTI]

    Z. -X. Shen; X. -W. Liu; H. -W. Zhang; B. Jones; D. N. C. Lin

    2007-03-30T23:59:59.000Z

    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.

  16. Half-life measurements of isomeric states populated in projectile fragmentation

    SciTech Connect (OSTI)

    Bowry, M.; Podolay, Zs. [Department of Physics, University of Surrey, Guildford, GU2 7XH (United Kingdom)

    2012-10-20T23:59:59.000Z

    The half-lives of excited isomeric states observed in {sup 195}Au, {sup 201}Tl and {sup 215}Rn are reported for the first time. Delayed {gamma}-rays were correlated with nuclei produced in the projectile fragmentation of relativistic {sup 238}U ions, unambiguously identified in terms of their atomic number (Z) and mass-to-charge ratio (A/Q) after traversing an in-flight separator. The observation of a long-lived isomeric state in {sup 195}Au with t{sub 1/2} = 16{sub -4}{sup +8}{mu}s is presented. Two shorter-lived isomeric states were detected in {sup 201}Tl and {sup 215}Rn with t{sub 1/2} = 95{sub -21}{sup +39} and 57{sub -12}{sup +21} ns respectively. In total 24 isomeric states were identified in different nuclei from Pt to Rn (A {approx} 200) during the current study, the majority of which were previously reported. The wealth of spectroscopic data provides the opportunity to determine the isomeric ratios over a wide range of Z, A and angular momentum (I h) of the reaction products. In particular, high-spin states with I Greater-Than-Or-Equivalent-To 18 h provide a robust test of theoretical models of fragmentation.

  17. Methods of separating short half-life radionuclides from a mixture of radionuclides

    DOE Patents [OSTI]

    Bray, Lane A. (Richland, WA); Ryan, Jack L. (West Richland, WA)

    1998-01-01T23:59:59.000Z

    The present invention is a method of obtaining a radionuclide product selected from the group consisting of .sup.223 Ra and .sup.225 Ac, from a radionuclide "cow" of .sup.227 Ac or .sup.229 Th respectively. The method comprises the steps of a) permitting ingrowth of at least one radionuclide daughter from said radionuclide "cow" forming an ingrown mixture; b) insuring that the ingrown mixture is a nitric acid ingrown mixture; c) passing the nitric acid ingrown mixture through a first nitrate form ion exchange column which permits separating the "cow" from at least one radionuclide daughter; d) insuring that the at least one radionuclide daughter contains the radionuclide product; e) passing the at least one radionuclide daughter through a second ion exchange column and separating the at least one radionuclide daughter from the radionuclide product and f) recycling the at least one radionuclide daughter by adding it to the "cow". In one embodiment the radionuclide "cow" is the .sup.227 Ac, the at least one daughter radionuclide is a .sup.227 Th and the product radionuclide is the .sup.223 Ra and the first nitrate form ion exchange column passes the .sup.227 Ac and retains the .sup.227 Th. In another embodiment the radionuclide "cow"is the .sup.229 Th, the at least one daughter radionuclide is a .sup.225 Ra and said product radionuclide is the .sup.225 Ac and the .sup.225 Ac and nitrate form ion exchange column retains the .sup.229 Th and passes the .sup.225 Ra/Ac.

  18. Precise half-life measurement of the superallowed beta(+) emitter (38)K(m)

    E-Print Network [OSTI]

    Ball, G. C.; Boisvert, G.; Bricault, P.; Churchman, R.; Dombsky, M.; Lindner, T.; Macdonald, J. A.; Vandervoort, E.; Bishop, S.; D'Auria, J. M.; Hardy, John C.; Iacob, V. E.; Leslie, J. R.; Mak, H. -B.

    2010-01-01T23:59:59.000Z

    . J. Schrewe, and K. S. Sharma, Nucl. Phys. A 405, 29 (1983). [5] A. P. Baerg, Metrologia 1, 131 (1965). [6] J. A. Cameron and B. Singh, Nucl. Data Sheets 109, 1 (2008). [7] G. T. A. Squier, W. E. Burcham, J. M. Freeman, R. J. Petty, S. D. Hoath...

  19. Method of separating short half-life radionuclides from a mixture of radionuclides

    DOE Patents [OSTI]

    Bray, Lane A. (Richland, WA); Ryan, Jack L. (West Richland, WA)

    1999-01-01T23:59:59.000Z

    The present invention is a method of removing an impurity of plutonium, lead or a combination thereof from a mixture of radionuclides that contains the impurity and at least one parent radionuclide. The method has the steps of (a) insuring that the mixture is a hydrochloric acid mixture; (b) oxidizing the acidic mixture and specifically oxidizing the impurity to its highest oxidation state; and (c) passing the oxidized mixture through a chloride form anion exchange column whereupon the oxidized impurity absorbs to the chloride form anion exchange column and the 22.sup.9 Th or 2.sup.27 Ac "cow" radionuclide passes through the chloride form anion exchange column. The plutonium is removed for the purpose of obtaining other alpha emitting radionuclides in a highly purified form suitable for medical therapy. In addition to plutonium; lead, iron, cobalt, copper, uranium, and other metallic cations that form chloride anionic complexes that may be present in the mixture; are removed from the mixture on the chloride form anion exchange column.

  20. Methods of separating short half-life radionuclides from a mixture of radionuclides

    DOE Patents [OSTI]

    Bray, L.A.; Ryan, J.L.

    1998-09-15T23:59:59.000Z

    The present invention is a method of obtaining a radionuclide product selected from the group consisting of {sup 223}Ra and {sup 225}Ac, from a radionuclide ``cow`` of {sup 227}Ac or {sup 229}Th respectively. The method comprises the steps of (a) permitting ingrowth of at least one radionuclide daughter from said radionuclide ``cow`` forming an ingrown mixture; (b) insuring that the ingrown mixture is a nitric acid ingrown mixture; (c) passing the nitric acid ingrown mixture through a first nitrate form ion exchange column which permits separating the ``cow`` from at least one radionuclide daughter; (d) insuring that the at least one radionuclide daughter contains the radionuclide product; (e) passing the at least one radionuclide daughter through a second ion exchange column and separating the at least one radionuclide daughter from the radionuclide product and (f) recycling the at least one radionuclide daughter by adding it to the ``cow``. In one embodiment the radionuclide ``cow`` is the {sup 227}Ac, the at least one daughter radionuclide is a {sup 227}Th and the product radionuclide is the {sup 223}Ra and the first nitrate form ion exchange column passes the {sup 227}Ac and retains the {sup 227}Th. In another embodiment the radionuclide ``cow`` is the {sup 229}Th, the at least one daughter radionuclide is a {sup 225}Ra and said product radionuclide is the {sup 225}Ac and the {sup 225}Ac and nitrate form ion exchange column retains the {sup 229}Th and passes the {sup 225}Ra/Ac. 8 figs.

  1. , 227 240 . Half-life Radioactive decay Reaction with 2200 m/s neutrons

    E-Print Network [OSTI]

    Hong, Deog Ki

    . 700-800 U2N3 UN2 . 1.2.5. 1.5 . , . UF4 UF6 UO2 HF . UO3 + 4HF Boils at 1 atm UF6 Black ~1427 8.95 UF4 Green 1036 1457 6.70 U4F17 Black 430 Disp. 6.94 U2F9 390 Disp. 7.06 UF5 White 348 Disp. 6.45 UF6 Colorless 64.05 56.54 5.06 UCl3 Olive green 837 1657 5.51 UCl4 Dark

  2. Global RNA Half-Life Analysis in Escherichia coli Reveals Positional Patterns of Transcript Degradation

    E-Print Network [OSTI]

    Church, George M.

    Degradation Douglas W. Selinger,1,3 Rini Mukherjee Saxena,2,3 Kevin J. Cheung,1 George M. Church,1 and Carsten to study global RNA degradation in wild-type Escherichia coli MG1655. RNA chemical half-lives were measured of operons degrade, on average, more quickly than the rest of the transcript, with stability increasing

  3. Prolonged lipoprotein half-life: effect on oxidative stability and physical features of lipoprotein particles 

    E-Print Network [OSTI]

    Simeral, Stephanie Bianco

    2002-01-01T23:59:59.000Z

    of lipoprotein density classes of VLDL, LDL, and high density lipoproteins (HDL) occur in accordance with effects observed in mammalian models of delayed LDL clearance such as the LDL-receptor knockout mouse that is also known to experience prolonged circulation...

  4. Precise half-life measurement of the superallowed beta(+) emitter (10)C

    E-Print Network [OSTI]

    Iacob, V. E.; Hardy, John C.; Golovko, V.; Goodwin, J.; Nica, N.; Park, H. I.; Trache, L.; Tribble, Robert E.

    2008-01-01T23:59:59.000Z

    and sent to a discriminator, whose output was split and processed in parallel by two separate systems, each with a different pre-set dominant nonextendable dead-time. The two data streams allowed us to test that our dead-time-corrected result... and discriminator threshold. Other special precautions were taken too. The tape- transport system is quite consistent in placing the collected source within ?3 mm of the center of the detector, but it is a mechanical device, and occasionally larger deviations...

  5. Method of separating short half-life radionuclides from a mixture of radionuclides

    DOE Patents [OSTI]

    Bray, L.A.; Ryan, J.L.

    1999-03-23T23:59:59.000Z

    The present invention is a method of removing an impurity of plutonium, lead or a combination thereof from a mixture of radionuclides that contains the impurity and at least one parent radionuclide. The method has the steps of (a) insuring that the mixture is a hydrochloric acid mixture; (b) oxidizing the acidic mixture and specifically oxidizing the impurity to its highest oxidation state; and (c) passing the oxidized mixture through a chloride form anion exchange column whereupon the oxidized impurity absorbs to the chloride form anion exchange column and the {sup 229}Th or {sup 227}Ac ``cow`` radionuclide passes through the chloride form anion exchange column. The plutonium is removed for the purpose of obtaining other alpha emitting radionuclides in a highly purified form suitable for medical therapy. In addition to plutonium, lead, iron, cobalt, copper, uranium, and other metallic cations that form chloride anionic complexes that may be present in the mixture are removed from the mixture on the chloride form anion exchange column. 8 figs.

  6. Average and recommended half-life values for two neutrino double beta decay: Upgrade-2013

    SciTech Connect (OSTI)

    Barabash, A. S. [Institute of Theoretical and Experimental Physics, B. Cheremushkinskaya 25, 117218 Moscow (Russian Federation)

    2013-12-30T23:59:59.000Z

    All existing positive results on two neutrino double beta decay in different nuclei were analyzed. Using the procedure recommended by the Particle Data Group, weighted average values for half-lives of {sup 48}Ca, {sup 76}Ge, {sup 82}Se, {sup 96}Zr, {sup 100}Mo, {sup 100}Mo?{sup 100}Ru (0{sub 1}{sup +}), {sup 116}Cd, {sup 130}Te, {sup 136}Xe, {sup 150}Nd, {sup 150}Nd?{sup 150}Sm (0{sub 1}{sup +}) and {sup 238}U were obtained. Existing geochemical data were analyzed and recommended values for half-lives of {sup 128}Te and {sup 130}Ba are proposed. I recommend the use of these results as the most currently reliable values for half-lives.

  7. Element abundances in solar energetic particles: two physical processes, two abundance patterns

    E-Print Network [OSTI]

    Reames, Donald V

    2015-01-01T23:59:59.000Z

    Abundances of elements comprising solar energetic particles (SEPs) come with two very different patterns. Historically called "impulsive" and "gradual" events, they have been studied for 40 years, 20 years by the Wind spacecraft. Gradual SEP events measure coronal abundances. They are produced when shock waves, driven by coronal mass ejections (CMEs), accelerate the ambient coronal plasma; we discuss the average abundances of 21 elements that differ from corresponding solar photospheric abundances by a well-known dependence on the first ionization potential (FIP) of the element. The smaller impulsive ("3He-rich") SEP events are associated with magnetic reconnection involving open field lines from solar flares or jets that also eject plasma to produce accompanying CMEs. These events produce striking heavy-element abundance enhancements, relative to coronal abundances, by an average factor of 3 at Ne, 9 at Fe, and 900 for elements with 76 0.1 are even more strongly associated with narrow, slow CMEs, cooler coro...

  8. Dual spatial maps of transcript and protein abundance in the...

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

    Dual spatial maps of transcript and protein abundance in the mouse brain. Dual spatial maps of transcript and protein abundance in the mouse brain. Abstract: Integrating...

  9. Mapping protein abundance patterns in the brain using voxelation...

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

    protein abundance patterns in the brain using voxelation combined with liquid chromatography and mass spectrometry. Mapping protein abundance patterns in the brain using voxelation...

  10. Topological Analysis of Protein Co-Abundance Networks Identifies...

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

    Topological Analysis of Protein Co-Abundance Networks Identifies Novel Host Targets Important for HCV Infection and Pathogenesis Topological Analysis of Protein Co-Abundance...

  11. Engineering Density of States of Earth Abundant Semiconductors...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    of States of Earth Abundant Semiconductors for Enhanced Thermoelectric Power Factor Engineering Density of States of Earth Abundant Semiconductors for Enhanced Thermoelectric...

  12. abundance life history: Topics by E-print Network

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

    of ectoparasite community and abundance across life history stages of avian host Environmental Sciences and Ecology Websites Summary: and abundance are often associated with the...

  13. Abundant C4 plants on the Tibetan Plateau during the Lateglacial and early Holocene

    E-Print Network [OSTI]

    Covino, Tim

    Abundant C4 plants on the Tibetan Plateau during the Lateglacial and early Holocene Elizabeth K t Plants using the C4 (Hatch-Slack) photosynthetic pathway are key for global food production and account of modern naturally-occurring C4 plant species at elevations up to 4500 m in Tibet and 3000 m in Africa

  14. Increased stray gas abundance in a subset of drinking water wells near Marcellus shale gas extraction

    E-Print Network [OSTI]

    Jackson, Robert B.

    Increased stray gas abundance in a subset of drinking water wells near Marcellus shale gas Pennsylvania, ex- amining natural gas concentrations and isotopic signatures with proximity to shale gas wells this transformation, with shale gas and other unconventional sources now yielding more than one- half of all US

  15. Abundance of narwhals (Monodon monoceros) on the hunting grounds in Greenland

    E-Print Network [OSTI]

    Laidre, Kristin L.

    Abundance of narwhals (Monodon monoceros) on the hunting grounds in Greenland M. P. HEIDE Greenland Institute of Natural Resources, Bok 570, 3900 Nuuk, Greenland (MPH, KLL, RGH) RUWPA, University to subsistence hunting by Inuit in Greenland and Canada. Scientific advice on the sustainable levels of removals

  16. NREL Explores Earth-Abundant Materials for Future Solar Cells (Fact Sheet)

    SciTech Connect (OSTI)

    Not Available

    2012-10-01T23:59:59.000Z

    Researchers at the National Renewable Energy Laboratory (NREL) are using a theory-driven technique - sequential cation mutation - to understand the nature and limitations of promising solar cell materials that can replace today's technologies. Finding new materials that use Earth-abundant elements and are easily manufactured is important for large-scale solar electricity deployment.

  17. Abundances of massive stars: some recent developments

    E-Print Network [OSTI]

    T. Morel

    2008-11-25T23:59:59.000Z

    Thanks to their usefulness in various fields of astrophysics (e.g. mixing processes in stars, chemical evolution of galaxies), the last few years have witnessed a large increase in the amount of abundance data for early-type stars. Two intriguing results emerging since the last reviews on this topic will be discussed: (a) nearby OB stars exhibit metal abundances generally lower than the solar/meteoritic estimates; (b) evolutionary models of single objects including rotation are largely unsuccessful in explaining the CNO properties of stars in the Galaxy and in the Magellanic clouds.

  18. Inferring Ecological Networks From Species Abundance Data

    E-Print Network [OSTI]

    Edinburgh, University of

    (LASSO), Sparse Bayesian Regression (SBR), Graphical Gaussian Models (GGMs) and Bayesian Networks (BNs to thank Marco Grzegorczyk for the answering my question about Bayesian networks and the MCMC methodsInferring Ecological Networks From Species Abundance Data Frank Dondelinger Master of Science

  19. A LOWER INITIAL ABUNDANCE OF SHORT-LIVED {sup 41}Ca IN THE EARLY SOLAR SYSTEM AND ITS IMPLICATIONS FOR SOLAR SYSTEM FORMATION

    SciTech Connect (OSTI)

    Liu, Ming-Chang [Institute of Astronomy and Astrophysics, Academia Sinica, Taipei, Taiwan (China); Chaussidon, Marc [Centre de Recherches Petrographiques et Geochimiques, CNRS, Nancy (France); Srinivasan, Gopalan [Center for Earth Science, Indian Institute of Science, Bangalore (India); McKeegan, Kevin D., E-mail: mcliu@asiaa.sinica.edu.tw [Department of Earth and Space Sciences, UCLA, Los Angeles, CA (United States)

    2012-12-20T23:59:59.000Z

    The short-lived radionuclide {sup 41}Ca plays an important role in constraining the immediate astrophysical environment and the formation timescale of the nascent solar system due to its extremely short half-life (0.1 Myr). Nearly 20 years ago, the initial ratio of {sup 41}Ca/{sup 40}Ca in the solar system was determined to be (1.41 {+-} 0.14) Multiplication-Sign 10{sup -8}, primarily based on two Ca-Al-rich Inclusions (CAIs) from the CV chondrite Efremovka. With an advanced analytical technique for isotopic measurements, we reanalyzed the potassium isotopic compositions of the two Efremovka CAIs and inferred the initial ratios of {sup 41}Ca/{sup 40}Ca to be (2.6 {+-} 0.9) Multiplication-Sign 10{sup -9} and (1.4 {+-} 0.6) Multiplication-Sign 10{sup -9} (2{sigma}), a factor of 7-10 lower than the previously inferred value. Considering possible thermal processing that led to lower {sup 26}Al/{sup 27}Al ratios in the two CAIs, we propose that the true solar system initial value of {sup 41}Ca/{sup 40}Ca should have been {approx}4.2 Multiplication-Sign 10{sup -9}. Synchronicity could have existed between {sup 26}Al and {sup 41}Ca, indicating a uniform distribution of the two radionuclides at the time of CAI formation. The new initial {sup 41}Ca abundance is 4-16 times lower than the calculated value for steady-state galactic nucleosynthesis. Therefore, {sup 41}Ca could have originated as part of molecular cloud materials with a free decay time of 0.2-0.4 Myr. Alternative possibilities, such as a last-minute input from a stellar source and early solar system irradiation, could not be definitively ruled out. This underscores the need for more data from diverse CAIs to determine the true astrophysical origin of {sup 41}Ca.

  20. The Isotopic Abundances of Magnesium in Stars

    E-Print Network [OSTI]

    Pamela Gay; David L. Lambert

    1999-11-11T23:59:59.000Z

    Isotopic abundance ratios 24^Mg:25^Mg:26^Mg are derived for 20 stars from high- resolution spectra of the MgH A-X 0-0 band at 5140AA. With the exception of the weak g-band giant HR 1299, the stars are dwarfs that sample the metallicity range -1.8 < [Fe/H] <0.0. The abundance of 25^Mg amd 26^Mg relative to the dominant isotope 24^Mg decreases with decreasing [Fe/H] in fair accord with predictions from a recent model of galactic chemical evolution in which the Mg isotopes are synthesised by massive stars. Several stars appear especially enriched in the heavier Mg isotopes suggesting contamination by material from the envelopes of intermediate-mass AGB stars.

  1. Topology in QCD and the axion abundance

    E-Print Network [OSTI]

    Ryuichiro Kitano; Norikazu Yamada

    2015-06-01T23:59:59.000Z

    The temperature dependence of the topological susceptibility (chi_t) in QCD essentially determines the abundance of the QCD axion in the Universe, and is commonly estimated, based on the instanton picture, to be a certain negative power of temperature. While lattice QCD should be able to check the instanton picture in principle, the region of the temperature where lattice calculations of chi_t are reliable is rather limited in practice, because existing methods on the lattice will probably fail when chi_t decreases rapidly with temperatures. In this work, two exploratory studies are presented. First, to realize the limitation of temperature we perform lattice calculations of chi_t in the quenched approximation and find that it becomes difficult with a given resource when T > 2 T_c. A possible way out is proposed and some test calculations are given. The absolute value and the temperature dependence of chi_t in real QCD can be significantly different from that in the quenched approximation, and is not well established over a wide range of the temperature above its critical value. Motivated by this fact and precedent arguments which disagree with the conventional instanton picture, we estimate the axion abundance in an extreme case where chi_t decreases much faster than the conventional power-like function. We find a significant enhancement of the axion abundance in such a case.

  2. Relative Abundance Measurements in Plumes and Interplumes

    E-Print Network [OSTI]

    Guennou, Chloé; Savin, Daniel Wolf

    2015-01-01T23:59:59.000Z

    We present measurements of relative elemental abundances in plumes and interplumes. Plumes are bright, narrow structures in coronal holes that extend along open magnetic field lines far out into the corona. Previous work has found that in some coronal structures the abundances of elements with a low first ionization potential (FIP) 10 eV). We have used EIS spectroscopic observations made on 2007 March 13 and 14 over an ~24 hour period to characterize abundance variations in plumes and interplumes. To assess their elemental composition, we have used a differential emission measure (DEM) analysis, which accounts for the thermal structure of the observed plasma. We have used lines from ions of iron, silicon, and sulfur. From these we have estimated the ratio of the iron and silicon FIP bias relative to that for sulfur. From the results, we have created FIP-bias-ratio maps. We find that the FIP-bias ratio is sometimes higher in plumes than in interplumes and that this enhancement can be time dependent. These res...

  3. Lithium abundances in globular cluster giants: NGC 1904, NGC 2808, and NGC 362

    E-Print Network [OSTI]

    D'Orazi, V; Angelou, G C; Bragaglia, A; Carretta, E; Lattanzio, J C; Lucatello, S; Momany, Y; Sollima, A; Beccari, G

    2015-01-01T23:59:59.000Z

    The presence of multiple populations in globular clusters has been well established thanks to high-resolution spectroscopy. It is widely accepted that distinct populations are a consequence of different stellar generations: intra-cluster pollution episodes are required to produce the peculiar chemistry observed in almost all clusters. Unfortunately, the progenitors responsible have left an ambiguous signature and their nature remains unresolved. To constrain the candidate polluters, we have measured lithium and aluminium abundances in more than 180 giants across three systems: NGC~1904, NGC~2808, and NGC~362. The present investigation along with our previous analysis of M12 and M5 affords us the largest database of simultaneous determinations of Li and Al abundances. Our results indicate that Li production has occurred in each of the three clusters. In NGC~362 we detected an M12-like behaviour, with first and second-generation stars sharing very similar Li abundances favouring a progenitor that is able to pro...

  4. High Dispersion Spectroscopy of Solar-type Superflare Stars. III. Lithium Abundances

    E-Print Network [OSTI]

    Honda, Satoshi; Maehara, Hiroyuki; Notsu, Shota; Shibayama, Takuya; Nogami, Daisaku; Shibata, Kazunari

    2015-01-01T23:59:59.000Z

    We report on the abundance analysis of Li in solar-type (G-type main sequence) superflare stars which were found by the analysis of Kepler photometric data. Li is a key element to understand the evolution of the stellar convection zone which reflects the age of solar-type stars. We performed the high dispersion spectroscopy of solar-type superflare stars with Subaru/HDS, and confirmed that 34 stars show no evidence of binarity in our previous study. In this study, we derived the Li abundances of these 34 objects. We investigate correlations of Li abundance with stellar atmospheric parameters, rotational velocity, and superflare activities to understand the nature of superflare stars and the possibility of the nucleosynthesis of Li by superflares. We confirm the large dispersion in the Li abundance, and the correlation with stellar parameters is not seen. As compared with the Li abundance in Hyades cluster which is younger than the Sun, it is suggested that half of the observed stars are younger than Hyades cl...

  5. abundance depth distribution: Topics by E-print Network

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

    12: 488-501 I N T R O DU C T I O N The species abundance distribution (SAD Enquist, Brian Joseph 4 Fauna, Distribution, Habitat Preference and Abundance CiteSeer Summary:...

  6. abundance distribution composition: Topics by E-print Network

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

    12: 488-501 I N T R O DU C T I O N The species abundance distribution (SAD Enquist, Brian Joseph 6 Fauna, Distribution, Habitat Preference and Abundance CiteSeer Summary:...

  7. abundance distribution results: Topics by E-print Network

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

    12: 488-501 I N T R O DU C T I O N The species abundance distribution (SAD Enquist, Brian Joseph 4 Fauna, Distribution, Habitat Preference and Abundance CiteSeer Summary:...

  8. Oxygen abundances in planet-harbouring stars. Comparison of different abundance indicators

    E-Print Network [OSTI]

    A. Ecuvillon; G. Israelian; N. C. Santos; N. G. Shchukina; M. Mayor; R. Rebolo

    2005-09-13T23:59:59.000Z

    We present a detailed and uniform study of oxygen abundances in 155 solar type stars, 96 of which are planet hosts and 59 of which form part of a volume-limited comparison sample with no known planets. EW measurements were carried out for the [O I] 6300 \\AA line and the O I triplet, and spectral synthesis was performed for several OH lines. NLTE corrections were calculated and applied to the LTE abundance results derived from the O I 7771-5 \\AA\\ triplet. Abundances from [O I], the O I triplet and near-UV OH were obtained in 103, 87 and 77 dwarfs, respectively. We present the first detailed and uniform comparison of these three oxygen indicators in a large sample of solar-type stars. There is good agreement between the [O/H] ratios from forbidden and OH lines, while the NLTE triplet shows a systematically lower abundance. We found that discrepancies between OH, [O I] and the O I triplet do not exceed 0.2 dex in most cases. We have studied abundance trends in planet host and comparison sample stars, and no obvious anomalies related to the presence of planets have been detected. All three indicators show that, on average, [O/Fe] decreases with [Fe/H] in the metallicity range -0.8oxygen overabundance of 0.1-0.2dex with respect to the comparison sample.

  9. Primordial Li abundance and massive particles

    SciTech Connect (OSTI)

    Latin-Capital-Letter-Eth apo, H. [Department of Physics, Akdeniz University, TR-07058, Antalya (Turkey)

    2012-10-20T23:59:59.000Z

    The problem of the observed lithium abundance coming from the Big Bang Nucleosynthesis is as of yet unsolved. One of the proposed solutions is including relic massive particles into the Big Bang Nucleosynthesis. We investigated the effects of such particles on {sup 4}HeX{sup -}+{sup 2}H{yields}{sup 6}Li+X{sup -}, where the X{sup -} is the negatively charged massive particle. We demonstrate the dominance of long-range part of the potential on the cross-section.

  10. Lithium abundances in exoplanet-hosts stars

    E-Print Network [OSTI]

    M. Castro; S. Vauclair; O. Richard; N. C. Santos

    2008-03-20T23:59:59.000Z

    Exoplanet-host stars (EHS) are known to present surface chemical abundances different from those of stars without any detected planet (NEHS). EHS are, on the average, overmetallic compared to the Sun. The observations also show that, for cool stars, lithium is more depleted in EHS than in NEHS. The overmetallicity of EHS may be studied in the framework of two different scenarii. We have computed main sequence stellar models with various masses, metallicities and accretion rates. The results show different profiles for the lithium destruction according to the scenario. We compare these results to the spectroscopic observations of lithium.

  11. SAFS-UW-1001 Abundance of Adult Hatchery and Wild

    E-Print Network [OSTI]

    Washington at Seattle, University of

    SAFS-UW-1001 July 2010 Abundance of Adult Hatchery and Wild Salmon by Region of the North Pacific Moore Foundation #12;Hatchery and Wild Salmon Abundance Page ii TABLE OF CONTENTS Page Introduction .............................................................................................................................. 1 Approaches to estimating wild salmon spawner abundances......................................... 1

  12. The circulating hemocytes of the white shrimp, Penaeus setiferus: origin, abundance, morphology, and function

    E-Print Network [OSTI]

    Fontaine, Clark Timothy

    1978-01-01T23:59:59.000Z

    mechanism contributing to the maintenance of hematological equilibrium. Research of this nature is needed for penaeid shrimp. The fall in hemocyte count could be due to retirement of hemocytes from circulation. Cells thus retired may adhere to tissues...THE CIRCULATING HENOCYTFS OF THE MH1TE SHRIMP& Penaeus seti. ferus: ORIGIN, ABUNDANCE, NORPHOLOGY, AND I'UNCTION A Thesis by Clark Timothy Fontaine Submitted to the Graduate College of Texas A&N University in Partial fulfillment...

  13. Relationship of Course Woody Debris to Red-Cockaded Woodpecker Prey Diversity and Abundance

    SciTech Connect (OSTI)

    Horn, G.S.

    1999-09-03T23:59:59.000Z

    The abundance of diversity of prey commonly used by the red-cockaded woodpecker were monitored in experimental plots in which course woody debris was manipulated. In one treatment, all the woody debris over four inches was removed. In the second treatment, the natural amount of mortality remained intact. The overall diversity of prey was unaffected; however, wood roaches were significantly reduced by removal of woody debris. The latter suggests that intensive utilizations or harvesting practices may reduce foraging.

  14. Element Abundances through the Cosmic Ages

    E-Print Network [OSTI]

    Max Pettini

    2003-03-12T23:59:59.000Z

    The horizon for studies of element abundances has expanded dramatically in the last ten years. Once the domain of astronomers concerned chiefly with stars and nearby galaxies, this field has now become a key component of observational cosmology, as technological advances have made it possible to measure the abundances of several chemical elements in a variety of environments at redshifts up to z = 4, when the universe was in its infancy. In this series of lectures I summarise current knowledge on the chemical make-up of distant galaxies observed directly in their starlight, and of interstellar and intergalactic gas seen in absorption against the spectra of bright background sources. The picture which is emerging is one where the universe at z = 3 already included many of the constituents of today's galaxies-even at these early times we see evidence for Population I and II stars, while the `smoking gun' for Population III objects may be hidden in the chemical composition of the lowest density regions of the intergalactic medium, yet to be deciphered.

  15. Beryllium abundances in stars hosting giant planets

    E-Print Network [OSTI]

    N. C. Santos; R. J. Garcia Lopez; G. Israelian; M. Mayor; R. Rebolo; A. Garcia-Gil; M. R. Perez de Taoro; S. Randich

    2002-02-25T23:59:59.000Z

    We have derived beryllium abundances in a wide sample of stars hosting planets, with spectral types in the range F7V-K0V, aimed at studying in detail the effects of the presence of planets on the structure and evolution of the associated stars. Predictions from current models are compared with the derived abundances and suggestions are provided to explain the observed inconsistencies. We show that while still not clear, the results suggest that theoretical models may have to be revised for stars with Teff<5500K. On the other hand, a comparison between planet host and non-planet host stars shows no clear difference between both populations. Although preliminary, this result favors a ``primordial'' origin for the metallicity ``excess'' observed for the planetary host stars. Under this assumption, i.e. that there would be no differences between stars with and without giant planets, the light element depletion pattern of our sample of stars may also be used to further investigate and constraint Li and Be depletion mechanisms.

  16. Oxygen Abundance Measurements of SHIELD Galaxies

    E-Print Network [OSTI]

    Haurberg, Nathalie C; Cannon, John M; Marshall, Melissa V

    2015-01-01T23:59:59.000Z

    We have derived oxygen abundances for 8 galaxies from the Survey of HI in Extremely Low-mass Dwarfs (SHIELD). The SHIELD survey is an ongoing study of very low-mass galaxies, with M$_{\\rm HI}$ between 10$^{6.5}$ and 10$^{7.5}$ M$_{\\odot}$, that were detected by the Arecibo Legacy Fast ALFA (ALFALFA) survey. H$\\alpha$ images from the WIYN 3.5m telescope show that these 8 SHIELD galaxies each possess one or two active star-forming regions which were targeted with long-slit spectral observations using the Mayall 4m telescope at KPNO. We obtained a direct measurement of the electron temperature by detection of the weak [O III] $\\lambda$4363 line in 2 of the HII regions. Oxygen abundances for the other HII regions were estimated using a strong-line method. When the SHIELD galaxies are plotted on a B-band luminosity-metallicity diagram they appear to suggest a slightly shallower slope to the relationship than normally seen. However, that offset is systematically reduced when the near-infrared luminosity is used ins...

  17. The Solar Heavy Element Abundances: I. Constraints from Stellar Interiors

    E-Print Network [OSTI]

    Delahaye, F; Delahaye, Franck; Pinsonneault, Marc

    2005-01-01T23:59:59.000Z

    The latest solar atmosphere models include non-LTE corrections and 3D hydrodynamic convection simulations. These models predict a significant reduction in the solar metal abundance, which leads to a serious conflict between helioseismic data and the predictions of solar interiors models. We demonstrate that the helioseismic constraints on the surface convection zone depth and helium abundance combined with stellar interiors models can be used to define the goodness of fit for a given chemical composition. After a detailed examination of the errors in the theoretical models we conclude that models constructed with the older solar abundances are consistent (seismic data. Models constructed with the proposed new low abundance scale are strongly disfavored, disagreeing at the 15 \\sigma level. We then use the sensitivity of the seismic properties to abundance changes to invert the problem and infer a seismic solar heavy element abundance mix with two components: meteoritic abundances, and th...

  18. Abundance ratios in hierarchical galaxy formation

    E-Print Network [OSTI]

    D. Thomas

    1999-01-18T23:59:59.000Z

    The chemical enrichment and stellar abundance ratios of galaxies which form in a hierarchical clustering scheme are calculated. For this purpose I adopt the star formation histories (SFH) as they are delivered by semi-analytic models in Kauffmann (1996}. It turns out that the average SFH of cluster ellipticals does not yield globally alpha-enhanced stellar populations. The star burst that occurs when the elliptical forms in the major merger plays therefore a crucial role in producing alpha-enhancement. Only under the assumption that the IMF is significantly flattened with respect to the Salpeter value during the burst, a Mg/Fe overabundant population can be obtained. In particular for the interpretation of radial gradients in metallicity and alpha-enhancement, the mixing of global and burst populations are of great importance. The model predicts bright field galaxies to be less alpha-enhanced than their counterparts in clusters.

  19. The Solar Heavy Element Abundances: I. Constraints from Stellar Interiors

    E-Print Network [OSTI]

    Franck Delahaye; Marc Pinsonneault

    2005-11-29T23:59:59.000Z

    The latest solar atmosphere models include non-LTE corrections and 3D hydrodynamic convection simulations. These models predict a significant reduction in the solar metal abundance, which leads to a serious conflict between helioseismic data and the predictions of solar interiors models. We demonstrate that the helioseismic constraints on the surface convection zone depth and helium abundance combined with stellar interiors models can be used to define the goodness of fit for a given chemical composition. After a detailed examination of the errors in the theoretical models we conclude that models constructed with the older solar abundances are consistent (seismic data. Models constructed with the proposed new low abundance scale are strongly disfavored, disagreeing at the 15 \\sigma level. We then use the sensitivity of the seismic properties to abundance changes to invert the problem and infer a seismic solar heavy element abundance mix with two components: meteoritic abundances, and the light metals CNONe. Seismic degeneracies between the best solutions for the elements arise for changes in the relative CNONe abundances and their effects are quantified. We obtain Fe/H=7.50+/-0.045+/-0.003(CNNe) and O/H=8.86+/-0.041+/-0.025(CNNe) for the relative CNNe in the GS98 mixture. The inferred solar oxygen abundance disagree with the abundance inferred from the 3D hydro models. Changes in the Ne abundance can mimic changes in O for the purposes of scalar constraints.Models constructed with low oxygen and high neon are inconsistent with the solar sound speed profile. The implications for the solar abundance scale are discussed.

  20. Planning Amid Abundance: Alaska’s FY 2013 Budget Process

    E-Print Network [OSTI]

    McBeath, Jerry

    2013-01-01T23:59:59.000Z

    state’s incentives for oil investment are excessive” (FDNM,increased oil industry investment. Planning Amid Abundance:oil corporations said that additional investment was

  1. Earth's most abundant mineral finally has a name | Argonne National...

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

    clarified the definition of Bridgmanite, a high-density form of magnesium iron silicate and the Earth's most abundant mineral - using Argonne National Laboratory's Advanced...

  2. Oxygen abundances in the most oxygen-rich spiral galaxies

    E-Print Network [OSTI]

    L. S. Pilyugin; T. X. Thuan; J. M. Vilchez

    2006-01-06T23:59:59.000Z

    Oxygen abundances in the spiral galaxies expected to be richest in oxygen are estimated. The new abundance determinations are based on the recently discovered ff-relation between auroral and nebular oxygen line fluxes in HII regions. We find that the maximum gas-phase oxygen abundance in the central regions of spiral galaxies is 12+log(O/H)~8.75. This value is significantly lower than the previously accepted value. The central oxygen abundance in the Milky Way is similar to that in other large spirals.

  3. Enhanced Detection of Low Abundant Human Plasma Proteins using...

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

    it especially difficult to detect low-abundant proteins in human biofluids such as blood plasma, an essential aspect for successful biomarker discovery efforts. Here we...

  4. High-Performance Thermoelectric Devices Based on Abundant Silicide...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Development of high-performance thermoelectric devices for vehicle waste heat recovery will include fundamental research to use abundant promising low-cost thermoelectric...

  5. Comparing halo bias from abundance and clustering

    E-Print Network [OSTI]

    Hoffmann, Kai; Gaztanaga, Enrique

    2015-01-01T23:59:59.000Z

    We model the abundance of haloes in the $\\sim(3 \\ \\text{Gpc}/h)^3$ volume of the MICE Grand Challenge simulation by fitting the universal mass function with an improved Jack-Knife error covariance estimator that matches theory predictions. We present unifying relations between different fitting models and new predictions for linear ($b_1$) and non-linear ($c_2$ and $c_3$) halo clustering bias. Different mass function fits show strong variations in their overall poor performance when including the low mass range ($M_h \\lesssim 3 \\ 10^{12} \\ M_{\\odot}/h$) in the analysis, which indicates noisy friends-of-friends halo detection given the MICE resolution ($m_p \\simeq 3 \\ 10^{10} \\ M_{\\odot}$/h). Together with fits from the literature we find an overall variance in the amplitudes of around $10%$ in the low mass and up to $50%$ in the high mass (galaxy cluster) range ($M_h > 10^{14} \\ M_{\\odot}/h$). These variations propagate into a $10%$ change in $b_1$ predictions and a $50%$ change in $c_2$ or $c_3$. Despite the...

  6. Topology in QCD and the axion abundance

    E-Print Network [OSTI]

    Kitano, Ryuichiro

    2015-01-01T23:59:59.000Z

    The temperature dependence of the topological susceptibility (chi_t) in QCD essentially determines the abundance of the QCD axion in the Universe, and is commonly estimated, based on the instanton picture, to be a certain negative power of temperature. While lattice QCD should be able to check the instanton picture in principle, the region of the temperature where lattice calculations of chi_t are reliable is rather limited in practice, because existing methods on the lattice will probably fail when chi_t decreases rapidly with temperatures. In this work, two exploratory studies are presented. First, to realize the limitation of temperature we perform lattice calculations of chi_t in the quenched approximation and find that it becomes difficult with a given resource when T > 2 T_c. A possible way out is proposed and some test calculations are given. The absolute value and the temperature dependence of chi_t in real QCD can be significantly different from that in the quenched approximation, and is not well est...

  7. CHEMICAL ABUNDANCES IN CLUSTERS OF GALAXIES

    E-Print Network [OSTI]

    Francesca Matteucci; Brad K. Gibson

    1995-03-14T23:59:59.000Z

    We study the origin of iron and alpha-elements (O, Mg, Si) in clusters of galaxies. In particular, we discuss the [O/Fe] ratio and the iron mass-to-luminosity ratio in the intracluster medium (ICM) and their link to the chemical and dynamical evolution of elliptical and lenticular galaxies. We adopt a detailed model of galactic evolution incorporating the development of supernovae- driven galactic winds which pollute the ICM with enriched ejecta. We demonstrate \\it quantitatively \\rm the crucial dependence upon the assumed stellar initial mass function in determining the evolution of the mass and abundances ratios of heavy elements in typical model ICMs. We show that completely opposite behaviours of [alpha/Fe] ratios (\\ie positive versus negative ratios) can be obtained by varying the initial mass function without altering the classic assumptions regarding type Ia supernovae progenitors or their nucleosynthesis. Our results indicate that models incorporating somewhat flatter-than-Salpeter initial mass functions (ie x approx 1, as opposed to x=1.35) are preferred, provided the intracluster medium iron mass-to-luminosity ratio, preliminary [alpha/Fe]>0 ASCA results, and present-day type Ia supernovae rates, are to be matched. A simple Virgo cluster simulation which adheres to these constraints shows that approx 70% of the measured ICM iron mass has its origin in type II supernovae, with the remainder being synthesized in type Ia systems.

  8. The bends in the slopes of radial abundance gradients in the disks of spiral galaxies -- do they exist?

    E-Print Network [OSTI]

    L. S. Pilyugin

    2002-10-17T23:59:59.000Z

    Spiral galaxies with a reported bend in the slope of gradient in the oxygen abundances (O/H)_R23, derived with traditionally used R23 - method, were examined. It is shown that the artificial origin of the reported bends can be naturally explained. Two reasons that result in a false bend in the slope of (O/H)_R23 gradient are indicated. It is concluded that at the present time there is no example of a galaxy with an undisputable established bend in the slope of the oxygen abundance gradient.

  9. Abundance profiling of extremely metal-poor stars and supernova properties in the early universe

    SciTech Connect (OSTI)

    Tominaga, Nozomu [Department of Physics, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Kobe, Hyogo 658-8501 (Japan); Iwamoto, Nobuyuki [Nuclear Data Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Nomoto, Ken'ichi, E-mail: tominaga@konan-u.ac.jp, E-mail: iwamoto.nobuyuki@jaea.go.jp, E-mail: nomoto@astron.s.u-tokyo.ac.jp [Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan)

    2014-04-20T23:59:59.000Z

    After the big bang nucleosynthesis, the first heavy element enrichment in the universe was made by a supernova (SN) explosion of a population (Pop) III star (Pop III SN). The abundance ratios of elements produced from Pop III SNe are recorded in abundance patterns of extremely metal-poor (EMP) stars. The observations of the increasing number of EMP stars have made it possible to statistically constrain the explosion properties of Pop III SNe. We present Pop III SN models whose nucleosynthesis yields well reproduce, individually, the abundance patterns of 48 such metal-poor stars as [Fe/H] ? – 3.5. We then derive relations between the abundance ratios of EMP stars and certain explosion properties of Pop III SNe: the higher [(C + N)/Fe] and [(C + N)/Mg] ratios correspond to the smaller ejected Fe mass and the larger compact remnant mass, respectively. Using these relations, the distributions of the abundance ratios of EMP stars are converted to those of the explosion properties of Pop III SNe. Such distributions are compared with those of the explosion properties of present day SNe: the distribution of the ejected Fe mass of Pop III SNe has the same peak as that of the present day SNe but shows an extended tail down to ?10{sup –2}-10{sup –5} M {sub ?}, and the distribution of the mass of the compact remnant of Pop III SNe is as wide as that of the present-day, stellar-mass black holes. Our results demonstrate the importance of large samples of EMP stars obtained by ongoing and future EMP star surveys and subsequent high-dispersion spectroscopic observations in clarifying the nature of Pop III SNe in the early universe.

  10. On the Alpha Activity of Natural Tungsten Isotopes

    E-Print Network [OSTI]

    F. A. Danevich A; A. Sh. Georgadze A; V. V. Kobychev A; S. S. Nagorny A; A. S. Nikolaiko A; W

    The indication for the ? decay of 180W with a half-life T ? 1/2 =1.1+0.8 ?0.4(stat)±0.3(syst)×1018 yr has been observed for the first time with the help of the super-low background 116CdWO4 crystal scintillators. In conservative approach the lower limit on half-life of 180W has been established as T ? 1/2 (180W) ? 0.7×1018 yr at 90 % C.L. Besides, new T ? 1/2 bounds were set for ? decay of

  11. Europium Isotopic Abundances in Very Metal-poor Stars

    E-Print Network [OSTI]

    Christopher Sneden; John J. Cowan; James E. Lawler; Scott Burles; Timothy C. Beers; George M. Fuller

    2002-01-28T23:59:59.000Z

    Europium isotopic abundance fractions are reported for the very metal-poor, neutron-capture-rich giant stars CS 22892-052, HD 115444, and BD +17 3248. The abundance fractions, derived from analysis of several strong Eu II lines appearing in high-resolution spectra of these stars, are in excellent agreement with each other and with their values in the Solar System: fraction(\\iso{Eu}{151}) ~= fraction(\\iso{Eu}{153}) ~= 0.5. Detailed abundance studies of very metal-poor stars have previously shown that the total elemental abundances of stable atoms with atomic numbers z >= 56 typically match very closely those of a scaled solar-system r-process abundance distribution. The present results for the first time extend this agreement to the isotopic level.

  12. Macroinvertebrate Abundance and Biomass: 2007 Data, BPA-51; Preliminary Report, February 10, 2009..

    SciTech Connect (OSTI)

    Holderman, Charles

    2009-02-10T23:59:59.000Z

    Four Excel files containing information on the 2007 macroinvertebrate data were initially provided to Statistical Consulting Services (SCS) by EcoAnalysts on 1/27/2009. These data files contained information on abundance and biomass data at the level of taxonomic groups. The data were subsequently reformatted and compiled, and aggregated for analysis by SCS. All descriptions and analyses below relate to this compiled data. Computations were carried out separately for each site over all sample periods. Basic summary information for both the abundance and biomass data is presented in Print Out No.2. The 14 sites varied widely in their minimum, mean, maximum and variance values. The number of observations ranged from 10 to 18. Some large abundance values (abundance > 40,000) were noted for sites KR6 and KR13. A more detailed summary of each site is given in Print Out No.3. Site KR3, for example, had a mean abundance of 6914 with a sample size of 17. The variance was 4591991 and the standard error of the mean was 1643. The skewness value, a measure of symmetry for the frequency distribution, was moderately large at 1.29 indicating an asymmetric distribution. Biomass for KR3 had a mean value of 0.87 g/m{sup 2} with 17 observations. The variance was 0.8872 and the standard error was 0.228 g/m{sup 2}. Skewness for biomass was also high at 1.29. Further examination of the quantiles and frequency plots for abundance and biomass also indicate considerable skewness. The stem and leaf diagram (frequency plot) for abundance in KR3 shows most of the data centered on smaller values with a few very large counts. The distribution for biomass has a similar pattern. Statistical tests for normality are significant for both response variables in KR3, thus, the hypothesis that the data originates from a symmetric normal distribution is rejected. Because sample size estimation and statistical inference assume normally distributed data, a transformation of the data is required prior to further analysis. As was the case for previous years, the natural logarithm was chosen as a transformation to mitigate distributional skewness. Abundance and biomass for the remaining sites were also notably skewed, therefore, these data were also log transformed prior to analysis. Summary information for the transformed data (referred to as L-abun and L-bio for abundance and biomass, respectively) are given in Print Out No.4. For site KR3, the logarithmic transformation reduced skewness value for biomass to -0.66. The distributions of abundance and biomass in the other sites also generally showed improvement as well. Hence, all subsequent statistical analyses reported here will be based on the log transformed data.

  13. Planning Amid Abundance: Alaska’s FY 2013 Budget Process

    E-Print Network [OSTI]

    McBeath, Jerry

    2013-01-01T23:59:59.000Z

    government revenues: heavy oil and natural gas” (FDNM,for new light crude from heavy oil, natural gas and shale

  14. Beryllium Abundances in Stars of One-Solar-Mass

    E-Print Network [OSTI]

    Ann Merchant Boesgaard; Julie A. Krugler

    2008-09-26T23:59:59.000Z

    We have determined Be abundances in 50 F and G dwarfs in the mass range of 0.9 $\\leq$ M$_\\odot$ $\\leq$ 1.1 as determined by Lambert & Reddy. The effective temperatures are 5600 to 6400 K and metallicities from $-$0.65 to +0.11. The spectra were taken primarily with Keck I + HIRES. The Be abundances were found via spectral synthesis of Be II lines near 3130 \\AA. The Be abundances were investigated as a function of age, temperature, metallicity and Li abundance in this narrow mass range. Even though our stars are similar in mass, they show a range in Be abundances of a factor of $>$40. We find that [Be/Fe] has no dependence on temperature, but does show a spread of a factor of 6 at a given temperature. The reality of the spread is shown by two identical stars which differ from each other by a factor of two only in their abundances of Li and Be. Our thin-disk-star sample fits the trend between Be abundance and [Fe/H] found for halo and thick disk stars, extending it to about 4 orders of magnitude in the two logarithmic quantities. Both Fe and Be appear to increase similarly over time in the Galaxy. One-third of our sample may be classified as subgiants; these more-evolved stars have lower Be abundances than the dwarfs. They have undergone Be depletion by slow mixing on the main sequence and Be dilution during their trip toward the red giant base. There are both Li and Be detections in 60 field stars in the "Li-plateau" of 5900 - 6300 K now and the abundances of the two light elements are correlated with a slope of 0.34 $\\pm$0.05, with greater Li depletion than Be depletion.

  15. Amorphous Silicon Thin-Film Transistors with DC Saturation Current Half-Life of More than 100 Years

    E-Print Network [OSTI]

    as the time for the TFT drain current to fall by 50% under DC voltage bias in saturation, the half with either back-channel etched (BCE) or back-channel passivated (BCP) structures (Fig. 1). The BCP structure passivates the back-side of the TFT channel "in situ" at the cost of an extra mask step. The gate nitride

  16. Measurement of the Double-Beta Decay Half-life of 136Xe in KamLAND-Zen

    E-Print Network [OSTI]

    Gando, A.

    2013-01-01T23:59:59.000Z

    by fallout from the Fukushima-I reactor accident in Marchof detector materials by Fukushima fallout, which includeCo are not detected near Fukushima or our soil samples, we

  17. Oxygen and nitrogen abundances in Virgo and field spirals

    E-Print Network [OSTI]

    L. S. Pilyugin; Mercedes Molla; Federico Ferrini; Jose M. Vilchez

    2001-12-03T23:59:59.000Z

    The oxygen and nitrogen abundances in the HII regions of the nine Virgo spirals of the sample from Skillman et al (1996) and in nine field spiral galaxies are re-determined with the recently suggested P - method. We confirm that there is an abundance segregation in the sample of Virgo spirals in the sense that the HI deficient Virgo spirals near the core of the cluster have higher oxygen abundances in comparison to the spirals at the periphery of the Virgo cluster. At the same time both the Virgo periphery and core spirals have counterparts among field spirals. We conclude that if there is a difference in the abundance properties of the Virgo and field spirals, this difference appears to be small and masked by the observational errors.

  18. astrophysically abundant atoms: Topics by E-print Network

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

    atomic data available so far and check the Mg abundances from individual lines in the Sun, four well studied A-type stars, and three reference metal-poor stars. With the adopted...

  19. abundance element: Topics by E-print Network

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

    physics, enable us to infer the temperature and hydrogen abundance profiles inside the Sun. These profiles also help in setting constraints on the input physics as well as on...

  20. Fundamental constraints on the abundances of chemotaxis proteins

    E-Print Network [OSTI]

    Bitbol, Anne-Florence

    2015-01-01T23:59:59.000Z

    Flagellated bacteria, such as Escherichia coli, perform directed motion in gradients of concentration of attractants and repellents in a process called chemotaxis. The E. coli chemotaxis signaling pathway is a model for signal transduction, but it has unique features. We demonstrate that the need for fast signaling necessitates high abundances of the proteins involved in this pathway. We show that further constraints on the abundances of chemotaxis proteins arise from the requirements of self-assembly, both of flagellar motors and of chemoreceptor arrays. All these constraints are specific to chemotaxis, and published data confirm that chemotaxis proteins tend to be more highly expressed than their homologs in other pathways. Employing a chemotaxis pathway model, we show that the gain of the pathway at the level of the response regulator CheY increases with overall chemotaxis protein abundances. This may explain why, at least in one E. coli strain, the abundance of all chemotaxis proteins is higher in media w...

  1. animal prey abundance: Topics by E-print Network

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

    overall abundance was higher overall during the August 1997 cruise than during the October 1996 cruise... Cady, Robert B 2012-06-07 42 The camp will expose students to local...

  2. abundance mineral: Topics by E-print Network

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

    between 55 and 72 Sm II lines per star. The abundance ratios of Sm relative to other rare earth elements in these stars are in agreement, and are consistent with ratios...

  3. Relative abundance of desert tortoises on the Nevada Test Site

    SciTech Connect (OSTI)

    Rautenstrauch, K.R.; O`Farrell, T.P.

    1993-12-31T23:59:59.000Z

    Seven hundred fifty-nine transects having a total length of 1,191 km were walked during 1981--1986 to determine the distribution and relative abundance of desert tortoises (Gopherus agassizii) on the Nevada Test Site (NTS). The abundance of tortoises on NTS was low to very low relative to other populations in the Mojave Desert. Sign of tortoises was found from 880 to 1,570 m elevation and was more abundant above 1,200 m than has been reported previously for Nevada. Tortoises were more abundant on NTS on the upper alluvial fans and slopes of mountains than in valley bottoms. They also were more common on or near limestone and dolomite mountains than on mountains of volcanic origin.

  4. A Temperature and Abundance Retrieval Method for Exoplanet Atmospheres

    E-Print Network [OSTI]

    Madhusudhan, Nikku

    We present a new method to retrieve molecular abundances and temperature profiles from exoplanet atmosphere photometry and spectroscopy. We run millions of one-dimensional (1D) atmosphere models in order to cover the large ...

  5. Relationships between body size and abundance in ecology

    E-Print Network [OSTI]

    Enquist, Brian Joseph

    , but interrelated, relation- ships between size and abundance that are often con- fused in the literature. Here, we and the structure and dynamics of eco- logical communities [3­5]. In addition, because body size is one

  6. Planning Amid Abundance: Alaska’s FY 2013 Budget Process

    E-Print Network [OSTI]

    McBeath, Jerry

    2013-01-01T23:59:59.000Z

    2011) “The Outlier State: Alaska’s FY 2012 Budget,” AnnualWestern States Budget Review. New York Times, selectedAbundance: Alaska’s FY 2013 Budget Process Abstract: This

  7. abundance isotopic: Topics by E-print Network

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

    24 Abundances and Isotope Ratios in the Magellanic Clouds: The Star Forming Environment of N113 Astrophysics (arXiv) Summary: With the goal of deriving the physical and...

  8. Beryllium, Lithium and Oxygen Abundances in F-type Stars

    E-Print Network [OSTI]

    R. J. Garcia Lopez; M. C. Dominguez Herrera; M. R. Perez de Taoro; C. Casares; J. L. Rasilla; R. Rebolo; C. Allende Prieto

    1997-10-07T23:59:59.000Z

    Beryllium and oxygen abundances have been derived in a sample of F-type field stars for which lithium abundances had been measured previously, with the aim of obtaining observational constraints to discriminate between the different mixing mechanisms proposed. Mixing associated with the transport of angular momentum in the stellar interior and internal gravity waves within the framework of rotating evolutionary models, appear to be promising ways to explain the observations.

  9. Massive stars vs. nebular abundances in the Orion nebula

    E-Print Network [OSTI]

    Sergio Simón Díaz

    2006-11-16T23:59:59.000Z

    The search of consistency between nebular and massive star abundances has been a longstanding problem. I briefly review what has been done regarding to this topic, also presenting a recent study focused on the Orion nebula: the O and Si stellar abundances resulting from a detailed and fully consistent spectroscopic analysis of the group of B stars associated with the Orion nebula are compared with the most recent nebular gas-phase results.

  10. Rate Analysis or a Possible Interpretation of Abundances

    E-Print Network [OSTI]

    Miklos Kiss

    2015-02-24T23:59:59.000Z

    Heavy elements are formed in nucleosynthesis processes. Abundances of these elements can be classified as elemental abundance, isotopic abundance, and abundance of nuclei. In this work we propose to change nucleon identification from the usual (Z,A) to (Z,N), which allows reading out new information from the measured abundances. We are interested in the neutron density required to reproduce the measured abundance of nuclei assuming equilibrium processes. This is only possible when two stable nuclei are separated by an unstable nucleus. At these places we investigated the neutron density required for equilibrium nucleosynthesis both isotopically and isotonically at temperatures of AGB interpulse and thermal pulse phases. We obtained an estimate for equilibrium nucleosynthesis neutron density in most of the cases. Next we investigated the possibility of partial formation of nuclei. We analyzed the meaning of the branching factor. We found a mathematical definition for the unified interpretation of a branching point closed at isotonic case and open at isotopic case. We introduce a more expressive variant of branching ratio called partial formation rate. With these we are capable of determining the characteristic neutron density values.

  11. DIRECT EVALUATION OF THE HELIUM ABUNDANCES IN OMEGA CENTAURI

    SciTech Connect (OSTI)

    Dupree, A. K.; Avrett, E. H., E-mail: dupree@cfa.harvard.edu, E-mail: eavrett@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

    2013-08-20T23:59:59.000Z

    A direct measure of the helium abundances from the near-infrared transition of He I at 1.08 {mu}m is obtained for two nearly identical red giant stars in the globular cluster Omega Centauri. One star exhibits the He I line; the line is weak or absent in the other star. Detailed non-local thermal equilibrium semi-empirical models including expansion in spherical geometry are developed to match the chromospheric H{alpha}, H{beta}, and Ca II K lines, in order to predict the helium profile and derive a helium abundance. The red giant spectra suggest a helium abundance of Y {<=} 0.22 (LEID 54064) and Y = 0.39-0.44 (LEID 54084) corresponding to a difference in the abundance {Delta}Y {>=} 0.17. Helium is enhanced in the giant star (LEID 54084) that also contains enhanced aluminum and magnesium. This direct evaluation of the helium abundances gives observational support to the theoretical conjecture that multiple populations harbor enhanced helium in addition to light elements that are products of high-temperature hydrogen burning. We demonstrate that the 1.08 {mu}m He I line can yield a helium abundance in cool stars when constraints on the semi-empirical chromospheric model are provided by other spectroscopic features.

  12. Carbon and Strontium Abundances of Metal-Poor Stars

    E-Print Network [OSTI]

    David K. Lai; Jennifer A. Johnson; Michael Bolte; Sara Lucatello

    2007-06-20T23:59:59.000Z

    We present carbon and strontium abundances for 100 metal-poor stars measured from R$\\sim $7000 spectra obtained with the Echellette Spectrograph and Imager at the Keck Observatory. Using spectral synthesis of the G-band region, we have derived carbon abundances for stars ranging from [Fe/H]$=-1.3$ to [Fe/H]$=-3.8$. The formal errors are $\\sim 0.2$ dex in [C/Fe]. The strontium abundance in these stars was measured using spectral synthesis of the resonance line at 4215 {\\AA}. Using these two abundance measurments along with the barium abundances from our previous study of these stars, we show it is possible to identify neutron-capture-rich stars with our spectra. We find, as in other studies, a large scatter in [C/Fe] below [Fe/H]$ = -2$. Of the stars with [Fe/H]$carbon-rich metal-poor stars. The Sr and Ba abundances show that three of the carbon-rich stars are neutron-capture-rich, while two have normal Ba and Sr. This fraction of carbon enhanced stars is consistent with other studies that include this metallicity range.

  13. Cyclotron production of {sup 61}Cu using natural Zn and enriched {sup 64}Zn targets

    SciTech Connect (OSTI)

    Asad, A. H.; Smith, S. V.; Chan, S.; Jeffery, C. M.; Morandeau, L.; Price, R. I. [RAPID PET Labs, Medical Technology and Physics, Sir Charles Gairdner Hospital, Perth, Australia, Imaging and Applied Physics, Curtin University, Perth, Australia, and Center of Excellence in Anti-matter Matter Studies, Australian National University, Can (Australia); Brookhaven National Laboratory, Upton, NY (United States) and Center of Excellence in Anti-matter Matter Studies, Australian National University, Canberra (Australia); RAPID PET Labs, Medical Technology and Physics, Sir Charles Gairdner Hospital, Perth (Australia); RAPID PET Labs, Medical Technology and Physics, Sir Charles Gairdner Hospital, Perth (Australia); Center of Excellence in Anti-matter Matter Studies, Australian National University, Canberra, Australia, and Chemistry, University of Western Australia, Pe (Australia); RAPID PET Labs, Medical Technology and Physics, Sir Charles Gairdner Hospital, Perth (Australia); RAPID PET Labs, Medical Technology and Physics, Sir Charles Gairdner Hospital, Perth, Australia and Physics, University of Western Australia, Perth (Australia)

    2012-12-19T23:59:59.000Z

    Copper-61 ({sup 61}Cu) shares with {sup 64}Cu certain advantages for PET diagnostic imaging, but has a shorter half-life (3.4hr vs. 12.7hr) and a greater probability of positron production per disintegration (61% vs. 17.9%). One important application is for in vivo imaging of hypoxic tissue. In this study {sup 61}Cu was produced using the {sup 64}Zn(p,{alpha}){sup 61}Cu reaction on natural Zn or enriched {sup 64}Zn targets. The enriched {sup 64}Zn (99.82%) was electroplated onto high purity gold or silver foils or onto thin Al discs. A typical target bombardment used 30{mu}A; at 11.7, 14.5 or 17.6MeV over 30-60min. The {sup 61}Cu (radiochemical purity of >95%) was separated using a combination of cation and anion exchange columns. The {sup 64}Zn target material was recovered after each run, for re-use. In a direct comparison with enriched {sup 64}Zn-target results, {sup 61}Cu production using the cheaper {sup nat}Zn target proved to be an effective alternative.

  14. ISO/GUM UNCERTAINTIES AND CIAAW (UNCERTAINTY TREATMENT FOR RECOMMENDED ATOMIC WEIGHTS AND ISOTOPIC ABUNDANCES)

    SciTech Connect (OSTI)

    HOLDEN,N.E.

    2007-07-23T23:59:59.000Z

    The International Organization for Standardization (ISO) has published a Guide to the expression of Uncertainty in Measurement (GUM). The IUPAC Commission on Isotopic Abundance and Atomic Weight (CIAAW) began attaching uncertainty limits to their recommended values about forty years ago. CIAAW's method for determining and assigning uncertainties has evolved over time. We trace this evolution to their present method and their effort to incorporate the basic ISO/GUM procedures into evaluations of these uncertainties. We discuss some dilemma the CIAAW faces in their present method and whether it is consistent with the application of the ISO/GUM rules. We discuss the attempt to incorporate variations in measured isotope ratios, due to natural fractionation, into the ISO/GUM system. We make some observations about the inconsistent treatment in the incorporation of natural variations into recommended data and uncertainties. A recommendation for expressing atomic weight values using a tabulated range of values for various chemical elements is discussed.

  15. Source apportionment of atmospheric PAHs in the Western Balkans by natural abundance radiocarbon analysis

    SciTech Connect (OSTI)

    Zdenek Zencak; Jana Klanova; Ivan Holoubek; Oerjan Gustafsson [Stockholm University, Stockholm (Sweden). Department of Applied Environmental Science

    2007-06-01T23:59:59.000Z

    Progress in source apportionment of priority combustion-derived atmospheric pollutants can be made by an inverse approach to inventory emissions, namely, receptor-based compound class-specific radiocarbon analysis (CCSRA) of target pollutants. In the present study, CCSRA of the combustion-derived polycyclic aromatic hydrocarbons (PAHs) present in the atmosphere of the countries of the former republic of Yugoslavia was performed. The carbon stable isotope composition ({delta}{sup 13}C) of PAHs varied between -27.68 and -27.19{per_thousand}, whereas {Delta}{sup 14}C values ranged from -568{per_thousand} for PAHs sampled in Kosovo to -288{per_thousand} for PAHs sampled in the Sarajevo area. The application of an isotopic mass balance model to these {Delta}{sup 14}C data revealed a significant contribution (35-65%) from the combustion of non-fossil material to the atmospheric PAH pollution, even in urban and industrialized areas. Furthermore, consistency was observed between the isotopic composition of PAHs obtained by high-volume sampling and those collected by passive sampling. This encourages the use of passive samplers for CCSRA applications. This marks the first time that a CCSRA investigation could be executed on a geographically wide scale, providing a quantitative field-based source apportionment, which points out that also non-fossil combustion processes should be targeted for remedial action. 36 refs., 1 fig., 3 tabs.

  16. Natural Abundance Radiocarbon Studies of Dissolved Organic Carbon (DOC) in the Marine Environment

    E-Print Network [OSTI]

    de Jesus, Roman P

    2008-01-01T23:59:59.000Z

    Press, San Diego. Bruland, K.W. , (1989) Complexation of6624), 480-482. Rue, E.L. , Bruland, K.W. , (1997) The rolemetal binding ligands (Bruland, 1989; Rue and Bruland, 1997;

  17. Natural abundance radiocarbon studies of dissolved organic carbon (DOC) in the marine environment

    E-Print Network [OSTI]

    De Jesus, Roman Paul

    2008-01-01T23:59:59.000Z

    Press, San Diego. Bruland, K.W. , (1989) Complexation of6624), 480-482. Rue, E.L. , Bruland, K.W. , (1997) The rolemetal binding ligands (Bruland, 1989; Rue and Bruland, 1997;

  18. -Amino acids, although less abundant than their -analogues, are also present in peptides and other natural

    E-Print Network [OSTI]

    . A number of methods for synthesis and transformations leading to -amino acids in diastereomerically as key structural components has recently attracted attention in synthetic organic chemistry because Polyhydroxyalkanoates (PHAs) are a family of carbon, energy and/or reducing power storage polymers, which

  19. N-15 NMR spectra of naturally abundant nitrogen in soil and aquatic...

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

    Soil samples include humic and fulvic acids from the Elliot soil, Minnesota Waskish peat and Florida Pahokee peat, as well as the Summit Hill soil humic acid and the Leonardite...

  20. Sugar in Two Steps Hexose sugars are naturally abundant, but it is often useful to

    E-Print Network [OSTI]

    Meyer, Karsten

    on the decay of U isotopes to Pb can be problematic if damaged parts of zircons, the primary uranium that was quickly depleted. Observations of molecular clouds indicate that ultraviolet radiation selectively depleted in 16O. Yurimoto and Kuramoto (p. 1763; see the Perspective by Yin) have developed a model

  1. A search for stars of very low metal abundance. VI. Detailed abundances of 313 metal-poor stars

    SciTech Connect (OSTI)

    Roederer, Ian U.; Preston, George W.; Thompson, Ian B.; Shectman, Stephen A.; Burley, Gregory S.; Kelson, Daniel D. [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Sneden, Christopher, E-mail: iur@umich.edu [Department of Astronomy, University of Texas at Austin, 1 University Station, C1400, Austin, TX 78712 (United States)

    2014-06-01T23:59:59.000Z

    We present radial velocities, equivalent widths, model atmosphere parameters, and abundances or upper limits for 53 species of 48 elements derived from high resolution optical spectroscopy of 313 metal-poor stars. A majority of these stars were selected from the metal-poor candidates of the HK Survey of Beers, Preston, and Shectman. We derive detailed abundances for 61% of these stars for the first time. Spectra were obtained during a 10 yr observing campaign using the Magellan Inamori Kyocera Echelle spectrograph on the Magellan Telescopes at Las Campanas Observatory, the Robert G. Tull Coudé Spectrograph on the Harlan J. Smith Telescope at McDonald Observatory, and the High Resolution Spectrograph on the Hobby-Eberly Telescope at McDonald Observatory. We perform a standard LTE abundance analysis using MARCS model atmospheres, and we apply line-by-line statistical corrections to minimize systematic abundance differences arising when different sets of lines are available for analysis. We identify several abundance correlations with effective temperature. A comparison with previous abundance analyses reveals significant differences in stellar parameters, which we investigate in detail. Our metallicities are, on average, lower by ?0.25 dex for red giants and ?0.04 dex for subgiants. Our sample contains 19 stars with [Fe/H] ?–3.5, 84 stars with [Fe/H] ?–3.0, and 210 stars with [Fe/H] ?–2.5. Detailed abundances are presented here or elsewhere for 91% of the 209 stars with [Fe/H] ?–2.5 as estimated from medium resolution spectroscopy by Beers, Preston, and Shectman. We will discuss the interpretation of these abundances in subsequent papers.

  2. Mimicking Nature

    E-Print Network [OSTI]

    Wythe, Kathy

    2007-01-01T23:59:59.000Z

    into lakes and rivers, and the impact different water management decisions could have. ?We?re trying to mimic nature,? said Dr. Jeff Arnold, research leader and agricultural engineer for the Grassland Soil and Water Research Laboratory in Temple, part..., director of Texas A&M University?s Spatial Sciences Laboratory and professor in the Departments of Ecosystem Science and MIMICKING NATURE Computer model helps manage nation?s, world?s waters #2; Management, and Biological and Agricultural Engineering...

  3. Naturalness redux

    E-Print Network [OSTI]

    Marco Fabbrichesi; Alfredo Urbano

    2015-04-21T23:59:59.000Z

    The idea of naturalness, as originally conceived, refers only to the finite renormalization of the Higgs boson mass induced by the introduction of heavier states. In this respect, naturalness is still a powerful heuristic principle in model building beyond the standard model whenever new massive states are coupled to the Higgs field. The most compelling case is provided by the generation of neutrino masses. In this paper we confront this problem from a new perspective. The right-handed sector responsible for the seesaw mechanism---which introduces a large energy threshold above the electroweak scale---is made supersymmetric to comply with naturalness while the standard model is left unchanged and non-supersymmetric. Cancellations necessary to the naturalness requirement break down only at two loops, thus offering the possibility to increase the right-handed neutrino mass scale up to one order of magnitude above the usual values allowed by naturalness. If also the weak boson sector of the standard model is made supersymmetric, cancellations break down at three loops and the scale of new physics can be further raised. In the type-I seesaw, this implementation provides right-handed neutrino masses that are natural and at the same time large enough to give rise to baryogenesis (via leptogenesis). The model contains a dark matter candidate and distinctive new physics in the leptonic sector.

  4. Lithium Abundances of the Local Thin Disk Stars

    E-Print Network [OSTI]

    David L. Lambert; Bacham E. Reddy

    2004-01-14T23:59:59.000Z

    Lithium abundances are presented for a sample of 181 nearby F and G dwarfs with accurate {\\it Hipparcos} parallaxes. The stars are on circular orbits about the Galactic centre and, hence, are identified as belonging to the thin disk. This sample is combined with two published surveys to provide a catalogue of lithium abundances, metallicities ([Fe/H]), masses, and ages for 451 F-G dwarfs, almost all belonging to the thin disk. The lithium abundances are compared and contrasted with published lithium abundances for F and G stars in local open clusters. The field stars span a larger range in [Fe/H] than the clusters for which [Fe/H] $\\simeq 0.0\\pm0.2$. The initial (i.e., interstellar) lithium abundance of the solar neighborhood, as derived from stars for which astration of lithium is believed to be unimportant, is traced from $\\log\\epsilon$(Li) = 2.2 at [Fe/H] = -1 to $\\log\\epsilon$(Li) = 3.2 at $+0.1$. This form for the evolution is dependent on the assumption that astration of lit hium is negligible for the stars defining the relation. An argument is advanced that this latter assumption may not be entirely correct, and, the evolution of lithium with [Fe/H] may be flatter than previously supposed. A sharp Hyades-like Li-dip is not seen among the field stars and appears to be replaced by a large spread among lithium abundances of stars more massive than the lower mass limit of the dip. Astration of lithium by stars of masses too low to participate in the Li-dip is discussed. These stars show little to no spread in lithium abundance at a given [Fe/H] and mass.

  5. Spatial Mapping of Protein Abundances in the Mouse Brain by Voxelation...

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

    Mapping of Protein Abundances in the Mouse Brain by Voxelation Integrated with High-Throughput Liquid Chromatography Spatial Mapping of Protein Abundances in the Mouse Brain by...

  6. Synthesis and Characterization of Earth Abundant and Nontoxic Metal Chalcogenides Produced via Aerosol Spray Pyrolysis for Photovoltaic Applications

    E-Print Network [OSTI]

    Davis, Patrick John

    2013-01-01T23:59:59.000Z

    and Characterization of Earth Abundant and Nontoxic Metaland Characterization of Earth Abundant and Nontoxic Metalalternatives to CIGS with all earth abundant and non-toxic

  7. New solar opacities, abundances, helioseismology, and neutrino fluxes

    E-Print Network [OSTI]

    John N. Bahcall; Aldo M. Serenelli; Sarbani Basu

    2005-01-19T23:59:59.000Z

    We construct solar models with the newly calculated radiative opacities from the Opacity Project (OP) and recently determined (lower) heavy element abundances. We compare results from the new models with predictions of a series of models that use OPAL radiative opacities, older determinations of the surface heavy element abundances, and refinements of nuclear reaction rates. For all the variations we consider, solar models that are constructed with the newer and lower heavy element abundances advocated by Asplund et al. (2005) disagree by much more than the estimated measuring errors with helioseismological determinations of the depth of the solar convective zone, the surface helium composition, the internal sound speeds, and the density profile. Using the new OP radiative opacities, the ratio of the 8B neutrino flux calculated with the older and larger heavy element abundances (or with the newer and lower heavy element abundances) to the total neutrino flux measured by the Sudbury Neutrino Observatory is 1.09 (0.87) with a 9% experimental uncertainty and a 16% theoretical uncertainty, 1 sigma errors.

  8. Oxygen abundance in the Sloan Digital Sky Survey

    E-Print Network [OSTI]

    F. Shi; X. Kong; F. Z. Cheng

    2006-03-10T23:59:59.000Z

    We present two samples of $\\hii$ galaxies from the Sloan Digital Sky Survey (SDSS) spectroscopic observations data release 3. The electron temperatures($T_e$) of 225 galaxies are calculated with the photoionized $\\hii$ model and $T_e$ of 3997 galaxies are calculated with an empirical method. The oxygen abundances from the $T_e$ methods of the two samples are determined reliably. The oxygen abundances from a strong line metallicity indicator, such as $R_{23}$, $P$, $N2$, and $O3N2$, are also calculated. We compared oxygen abundances of $\\hii$ galaxies obtained with the $T_e$ method, $R_{23}$ method, $P$ method, $N2$ method, and $O3N2$method. The oxygen abundances derived with the $T_e$ method are systematically lower by $\\sim$0.2 dex than those derived with the $R_{23}$ method, consistent with previous studies based on $\\hii$ region samples. No clear offset for oxygen abundance was found between $T_e$ metallicity and $P$, $N2$ and $O3N2$ metallicity. When we studied the relation between N/O and O/H, we found that in the metallicity regime of $\\zoh > 7.95$, the large scatter of the relation can be explained by the contribution of small mass stars to the production of nitrogen. In the high metallicity regime, $\\zoh > 8.2$, nitrogen is primarily a secondary element produced by stars of all masses.

  9. Bureau of Economic Geology, The University of Texas at Austin Natural Gas Trends

    E-Print Network [OSTI]

    Texas at Austin, University of

    1 Bureau of Economic Geology, The University of Texas at Austin Natural Gas Trends LNG 17 NYC, June the market will bear. #12;2 Dr. Michelle Michot Foss, CEE/BEG/JSG/UT Natural Gas Can Bring Multiple Benefits we get there? "Safe clean affordable Natural gas is a desirableSafe, clean, affordable, (abundant

  10. Natural Predator

    E-Print Network [OSTI]

    Wythe, Kathy

    2006-01-01T23:59:59.000Z

    tx H2O | pg. 10 Natural Predator Story by Kathy Wythe Natural Predator Foreign beetle shows promise for controlling saltcedar In the northern part of the Texas Panhandle andalong the West Texas banks of the Colorado andPecos rivers, Texas... scientists are successfully intro- ducing a foreign beetle to help control an invasive and exotic water-thirsty plant. Saltcedar, or Tamarix, was introduced to the western United States in the 1800s from central Asia as an ornamental tree and planted...

  11. What Is The Neon Abundance Of The Sun?

    E-Print Network [OSTI]

    John N. Bahcall; Sarbani Basu; Aldo M. Serenelli

    2005-05-16T23:59:59.000Z

    We have evolved a series of thirteen complete solar models that utilize different assumed heavy element compositions. Models that are based upon the heavy element abundances recently determined by Asplund, Grevesse, and Sauval (2005) are inconsistent with helioseismological measurements. However, models in which the neon abundance is increased by 0.4-0.5 dex to log N(Ne) = 8.29 +- 0.05 (on the scale in which log N(H) = 12) are consistent with the helioseismological measurements even though the other heavy element abundances are in agreement with the determinations of Asplund et al. (2005). These results sharpen and strengthen an earlier study by Antia and Basu (2005). The predicted solar neutrino fluxes are affected by the uncertainties in the composition by less than their 1sigma theoretical uncertainties.

  12. The chemical abundances of the Ap star HD94660

    SciTech Connect (OSTI)

    Giarrusso, M. [Università di Catania, Dipartimento di Fisica e Astronomia, Sezione Astrofisica, Via S. Sofia 78, 95123 Catania (Italy); INAF - Osservatorio Astrofisico di Catania, via S. Sofia 78, 95123 Catania (Italy); INFN - Laboratori Nazionali del Sud (Italy)

    2014-05-09T23:59:59.000Z

    In this work I present the determination of chemical abundances of the Ap star HD94660, a possible rapid oscillating star. As all the magnetic chemically peculiar objects, it presents CNO underabundance and overabundance of iron peak elements of ?100 times and of rare earths up to 4 dex with respect to the Sun. The determination was based on the conversion of the observed equivalent widths into abundances simultaneously to the determination of effective temperature and gravity. Since the Balmer lines of early type stars are very sensitive to the surface gravity while the flux distribution is sensitive to the effective temperature, I have adopted an iterative procedure to match the H{sub ?} line profile and the observed UV-Vis-NIR magnitudes of HD94660 looking for a consistency between the metallicity of the atmosphere model and the derived abundances. From my spectroscopic analysis, this star belongs to the no-rapid oscillating class.

  13. The effects of He I 10830 on helium abundance determinations

    E-Print Network [OSTI]

    Aver, Erik; Skillman, Evan D

    2015-01-01T23:59:59.000Z

    Observations of helium and hydrogen emission lines from metal-poor extragalactic H II regions provide an independent method for determining the primordial helium abundance, Y_p. Traditionally, the emission lines employed are in the visible wavelength range, and the number of suitable lines is limited. Furthermore, when using these lines, large systematic uncertainties in helium abundance determinations arise due to the degeneracy of physical parameters, such as temperature and density. Recently, Izotov, Thuan, & Guseva (2014) have pioneered adding the He 10830 infrared emission line in helium abundance determinations. The strong electron density dependence of He 10830 makes it ideal for better constraining density, potentially breaking the degeneracy with temperature. We revisit our analysis of the dataset published by Izotov, Thuan, & Stasinska (2007) and incorporate the newly available observations of He 10830 by scaling them using the observed-to-theoretical Paschen-gamma ratio. The solutions are b...

  14. Spectroscopic Abundances and Membership in the Wolf 630 Moving Group

    E-Print Network [OSTI]

    Bubar, Eric J

    2010-01-01T23:59:59.000Z

    The concept of kinematic assemblages evolving from dispersed stellar clusters has remained contentious since Eggen's initial formulation of moving groups in the 1960's. With high quality parallaxes from the Hipparcos space astrometry mission, distance measurements for thousands of nearby, seemingly isolated stars are currently available. With these distances, a high resolution spectroscopic abundance analysis can be brought to bear on the alleged members of these moving groups. If a structure is a relic of an open cluster, the members can be expected to be monolithic in age and abundance inasmuch as homogeneity is observed in young open clusters. In this work we have examined 34 putative members of the proposed Wolf 630 moving group using high resolution stellar spectroscopy. The stars of the sample have been chemically tagged to determine abundance homogeneity and confirm the existence of a homogeneous subsample of 19 stars. Fitting the homogeneous subsample with Yale-Yonsei isochrones yields a single evolut...

  15. DETERMINING THE INITIAL HELIUM ABUNDANCE OF THE SUN

    SciTech Connect (OSTI)

    Serenelli, Aldo M. [Max Planck Institute for Astrophysics, Karl Schwarzschild Str. 1, Garching D-85471 (Germany); Basu, Sarbani, E-mail: aldos@mpa-garching.mpg.d [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States)

    2010-08-10T23:59:59.000Z

    We determine the dependence of the initial helium abundance and the present-day helium abundance in the convective envelope of solar models (Y {sub ini} and Y {sub surf}, respectively) on the parameters that are used to construct the models. We do so by using reference standard solar models (SSMs) to compute the power-law coefficients of the dependence of Y {sub ini} and Y {sub surf} on the input parameters. We use these dependencies to determine the correlation between Y {sub ini} and Y {sub surf} and use this correlation to eliminate uncertainties in Y {sub ini} from all solar model input parameters except the microscopic diffusion rate. We find an expression for Y {sub ini} that depends only on Y {sub surf} and the diffusion rate. By adopting the helioseismic determination of solar surface helium abundance, Y {sup surf} {sub sun} = 0.2485 {+-} 0.0035, and an uncertainty of 20% for the diffusion rate, we find that the initial solar helium abundance, Y {sup ini} {sub sun}, is 0.278 {+-} 0.006 independently of the reference SSMs (and particularly on the adopted solar abundances) used in the derivation of the correlation between Y {sub ini} and Y {sub surf}. When non-SSMs with extra mixing are used, then we derive Y {sup ini} {sub sun} = 0.273 {+-} 0.006. In both cases, the derived Y {sup ini} {sub sun} value is higher than that directly derived from solar model calibrations when the low-metallicity solar abundances (e.g., by Asplund et al.) are adopted in the models.

  16. The Formation of the First Low-Mass Stars From Gas With Low Carbon and Oxygen Abundances

    E-Print Network [OSTI]

    Volker Bromm; Abraham Loeb

    2003-10-21T23:59:59.000Z

    The first stars in the Universe are predicted to have been much more massive than the Sun. Gravitational condensation accompanied by cooling of the primordial gas due to molecular hydrogen, yields a minimum fragmentation scale of a few hundred solar masses. Numerical simulations indicate that once a gas clump acquires this mass, it undergoes a slow, quasi-hydrostatic contraction without further fragmentation. Here we show that as soon as the primordial gas - left over from the Big Bang - is enriched by supernovae to a carbon or oxygen abundance as small as ~0.01-0.1% of that found in the Sun, cooling by singly-ionized carbon or neutral oxygen can lead to the formation of low-mass stars. This mechanism naturally accommodates the discovery of solar mass stars with unusually low (10^{-5.3} of the solar value) iron abundance but with a high (10^{-1.3} solar) carbon abundance. The minimum stellar mass at early epochs is partially regulated by the temperature of the cosmic microwave background. The derived critical abundances can be used to identify those metal-poor stars in our Milky Way galaxy with elemental patterns imprinted by the first supernovae.

  17. Asteroseismic determination of helium abundance in stellar envelopes

    E-Print Network [OSTI]

    Sarbani Basu; Anwesh Mazumdar; H. M Antia; Pierre Demarque

    2004-02-15T23:59:59.000Z

    Intermediate degree modes of the solar oscillations have previously been used to determine the solar helium abundance to a high degree of precision. However, we cannot expect to observe such modes in other stars. In this work we investigate whether low degree modes that should be available from space-based asteroseismology missions can be used to determine the helium abundance, Y, in stellar envelopes with sufficient precision. We find that the oscillatory signal in the frequencies caused by the depression in \\Gamma_1 in the second helium ionisation zone can be used to determine the envelope helium abundance of low mass main sequence stars. For frequency errors of 1 part in 10^4, we expect errors \\sigma_Y in the estimated helium abundance to range from 0.03 for 0.8M_sun stars to 0.01 for 1.2M_sun stars. The task is more complicated in evolved stars, such as subgiants, but is still feasible if the relative errors in the frequencies are less than 10^{-4}.

  18. Coronae of Stars with Super Solar Elemental Abundances

    E-Print Network [OSTI]

    Peretz, Uria; Drake, Stephen A

    2015-01-01T23:59:59.000Z

    Coronal elemental abundances are known to deviate from the photospheric values of their parent star, with the degree of deviation depending on the First Ionization Potential (FIP). This study focuses on the coronal composition of stars with super-solar photospheric abundances. We present the coronal abundances of six such stars: 11 LMi, $\\iota$ Hor, HR 7291, $\\tau$ Boo, and $\\alpha$ Cen A and B. These stars all have high-statistics X-ray spectra, three of which are presented for the first time. The abundances measured in this paper are obtained using the line-resolved spectra of the Reflection Grating Spectrometer (RGS) in conjunction with the higher throughput EPIC-pn camera spectra on board the XMM-Newton observatory. A collisionally ionized plasma model with two or three temperature components is found to represent the spectra well. All elements are found to be consistently depleted in the coronae compared to their respective photospheres. For 11 LMi and $\\tau$ Boo no FIP effect is present, while $\\iota$ H...

  19. Implications of Elemental Abundances in Dwarf Spheroidal Galaxies

    E-Print Network [OSTI]

    Takuji Tsujimoto

    2005-09-29T23:59:59.000Z

    Unusual elemental abundance patterns observed for stars belonging to nearby dwarf spheroidal (dSph) galaxies are discussed. Analysis of the [alpha/H] vs. [Fe/H] diagrams where alpha represents Mg or average of alpha-elements reveals that Fe from Type Ia supernovae (SNe Ia) does not contribute to the stellar abundances in the dSph galaxies where the member stars exhibit low alpha/Fe ratios except for the most massive dSph galaxy, the Sagitarrius. The more massive dwarf (irregular) galaxy, the Large Magellanic Cloud, also have an SNe Ia signature in the stellar abundances. These findings suggest that the condition of whether SNe Ia contribute to chemical evolution in dwarf galaxies is likely to depend on the mass scale of galaxies. Unusual Mg abundances in some dSph stars are also found to be the origin of the large scatter in the [Mg/Fe] ratios and responsible for a seemingly decreasing [Mg/Fe] feature with increasing [Fe/H]. In addition, the lack of massive stars in the dSph galaxies does not satisfactorily account for the low-alpha signature. Considering the assemblage of deficient elements (O, Mg, Si, Ca, Ti, and Zn), all of which are synthesized in pre-SN massive stars and in SN explosions, the low-alpha signature appears to reflect the heavy-element yields of massive stars with smaller rotation compared to solar neighborhood stars.

  20. Implications of Elemental Abundances in Dwarf Spheroidal Galaxies

    E-Print Network [OSTI]

    Tsujimoto, T

    2005-01-01T23:59:59.000Z

    Unusual elemental abundance patterns observed for stars belonging to nearby dwarf spheroidal (dSph) galaxies are discussed. Analysis of the [alpha/H] vs. [Fe/H] diagrams where alpha represents Mg or average of alpha-elements reveals that Fe from Type Ia supernovae (SNe Ia) does not contribute to the stellar abundances in the dSph galaxies where the member stars exhibit low alpha/Fe ratios except for the most massive dSph galaxy, the Sagitarrius. The more massive dwarf (irregular) galaxy, the Large Magellanic Cloud, also have an SNe Ia signature in the stellar abundances. These findings suggest that the condition of whether SNe Ia contribute to chemical evolution in dwarf galaxies is likely to depend on the mass scale of galaxies. Unusual Mg abundances in some dSph stars are also found to be the origin of the large scatter in the [Mg/Fe] ratios and responsible for a seemingly decreasing [Mg/Fe] feature with increasing [Fe/H]. In addition, the lack of massive stars in the dSph galaxies does not satisfactorily a...

  1. abundant energy source: Topics by E-print Network

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

    abundant energy source First Page Previous Page 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 The SolarWiki Solar energy is...

  2. Are beryllium abundances anomalous in stars with giant planets?

    E-Print Network [OSTI]

    N. C. Santos; G. Israelian; R. J Garcia Lopez; M. Mayor; R. Rebolo; S. Randich; A. Ecuvillon; C. Dominguez Cerdena

    2004-08-05T23:59:59.000Z

    In this paper we present beryllium (Be) abundances in a large sample of 41 extra-solar planet host stars, and for 29 stars without any known planetary-mass companion, spanning a large range of effective temperatures. The Be abundances were derived through spectral synthesis done in standard Local Thermodynamic Equilibrium, using spectra obtained with various instruments. The results seem to confirm that overall, planet-host stars have ``normal'' Be abundances, although a small, but not significant, difference might be present. This result is discussed, and we show that this difference is probably not due to any stellar ``pollution'' events. In other words, our results support the idea that the high-metal content of planet-host stars has, overall, a ``primordial'' origin. However, we also find a small subset of planet-host late-F and early-G dwarfs that might have higher than average Be abundances. The reason for the offset is not clear, and might be related either to the engulfment of planetary material, to galactic chemical evolution effects, or to stellar-mass differences for stars of similar temperature.

  3. abundant nuclear copies: Topics by E-print Network

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

    abundant nuclear copies First Page Previous Page 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 Author's personal copy Nuclear...

  4. GASEOUS CO ABUNDANCE-AN EVOLUTIONARY TRACER FOR MOLECULAR CLOUDS

    SciTech Connect (OSTI)

    Liu Tie; Wu Yuefang; Zhang Huawei, E-mail: liutiepku@gmail.com, E-mail: ywu@pku.edu.cn [Department of Astronomy, Peking University, Beijing 100871 (China)

    2013-09-20T23:59:59.000Z

    Planck cold clumps are among the most promising objects to investigate the initial conditions of the evolution of molecular clouds. In this work, by combing the dust emission data from the survey of the Planck satellite with the molecular data of {sup 12}CO/{sup 13}CO/C{sup 18}O (1-0) lines from observations with the Purple Mountain Observatory 13.7 m telescope, we investigate the CO abundance, CO depletion, and CO-to-H{sub 2} conversion factor of 674 clumps in the early cold cores sample. The median and mean values of the CO abundance are 0.89 Multiplication-Sign 10{sup -4} and 1.28 Multiplication-Sign 10{sup -4}, respectively. The mean and median of CO depletion factor are 1.7 and 0.9, respectively. The median value of X{sub CO-to-H{sub 2}} for the whole sample is 2.8 Multiplication-Sign 10{sup 20} cm{sup -2} K{sup -1} km{sup -1} s. The CO abundance, CO depletion factor, and CO-to-H{sub 2} conversion factor are strongly (anti-)correlated to other physical parameters (e.g., dust temperature, dust emissivity spectral index, column density, volume density, and luminosity-to-mass ratio). To conclude, the gaseous CO abundance can be used as an evolutionary tracer for molecular clouds.

  5. INTRODUCTION Information on the abundance of large whales in Greenland

    E-Print Network [OSTI]

    Laidre, Kristin L.

    INTRODUCTION Information on the abundance of large whales in Greenland waters, including fin whales surveys were conducted in West Greenland by the Greenland Fisheries Research Institute (m/v Regina Maris when survey conditions are optimal in Greenlandic waters. Between 1983 and 1993, visual aerial surveys

  6. abundance bed net: Topics by E-print Network

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

    abundance bed net First Page Previous Page 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 Open Access Impact of...

  7. Carbon Abundances in the Galactic Thin and Thick Disks

    E-Print Network [OSTI]

    T. Bensby; S. Feltzing

    2005-06-07T23:59:59.000Z

    Although carbon is, together with oxygen and nitrogen, one of the most important elements in the study of galactic chemical evolution its production sites are still poorly known and have been much debated (see e.g. Gustafsson et al. 1999; Chiappini et al. 2003). To trace the origin and evolution of carbon we have determined carbon abundances from the forbidden [C I] line at 8727 A and made comparisons to oxygen abundances from the forbidden [O I] line at 6300 A in a sample of 51 nearby F and G dwarf stars. These data and the fact that the forbidden [C I] and [O I] lines are very robust abundance indicators (they are essentially insensitive to deviations from LTE and uncertainties in the stellar parameters, see, e.g., Gustafsson et al. 1999; Asplund et al. 2005) enable us to very accurately measure the C/O ratio as well as individual C and O abundances. Our first results indicate that the time-scale for the main source that contribute to the carbon enrichment of the interstellar medium operate on the same time-scale as those that contribute to the iron enrichment (and can possibly be AGB stars...)

  8. RECYCLABILITY CHALLENGES IN "ABUNDANT" MATERIAL-BASED TECHNOLOGIES Annick Anctila

    E-Print Network [OSTI]

    RECYCLABILITY CHALLENGES IN "ABUNDANT" MATERIAL-BASED TECHNOLOGIES Annick Anctila and Fthenakisa of photovoltaic installations grow, greatly displacing traditional power- generation infrastructures, recycling a take-back- or recycling-program ahead of time. Our work explores the potential for material recycling

  9. Zirconium, barium, lanthanum, and europium abundances in open clusters

    E-Print Network [OSTI]

    Friel, Eileen D.

    We present an analysis of the s-process elements Zr, Ba, and La and the r-process element Eu in a sample of 50 stars in 19 open clusters. Stellar abundances of each element are based on measures of a minimum of two lines ...

  10. ZIRCONIUM, BARIUM, LANTHANUM, AND EUROPIUM ABUNDANCES IN OPEN CLUSTERS

    SciTech Connect (OSTI)

    Jacobson, Heather R. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48823 (United States); Friel, Eileen D., E-mail: jacob189@msu.edu, E-mail: efriel@indiana.edu, E-mail: hrj@mit.edu [Department of Astronomy, Indiana University, Bloomington, IN 47405 (United States)

    2013-04-15T23:59:59.000Z

    We present an analysis of the s-process elements Zr, Ba, and La and the r-process element Eu in a sample of 50 stars in 19 open clusters. Stellar abundances of each element are based on measures of a minimum of two lines per species via both equivalent width and spectrum synthesis techniques. We investigate cluster mean neutron-capture abundance trends as a function of cluster age and location in the Milky Way disk and compare them to results found in other studies in the literature. We find a statistically significant trend of increasing cluster [Ba/Fe] as a function of decreasing cluster age, in agreement with recent findings for other open cluster samples, supporting the increased importance of low-mass asymptotic giant branch stars to the generation of s-process elements. However, the other s-process elements, [La/Fe] and [Zr/Fe], do not show similar dependences, in contrast to theoretical expectations and the limited observational data from other studies. Conversely, cluster [Eu/Fe] ratios show a slight increase with increasing cluster age, although with marginal statistical significance. Ratios of [s/r]-process abundances, [Ba/Eu] and [La/Eu], however, show more clearly the increasing efficiency of s-process relative to r-process enrichment in open cluster chemical evolution, with significant increases among younger clusters. Last, cluster neutron-capture element abundances appear to be independent of Galactocentric distance. We conclude that a homogeneous analysis of a larger sample of open clusters is needed to resolve the apparent discrepant conclusions between different studies regarding s-process element abundance trends with age to better inform models of galactic chemical evolution.

  11. Line temperatures and elemental abundances in HII galaxies

    E-Print Network [OSTI]

    Enrique Perez-Montero; Angeles I. Diaz

    2003-09-02T23:59:59.000Z

    We present long-slit spectrophotometric observations in the red and near infrared of 12 HII galaxies. The spectral range includes the sulphur lines [SII] at wavelengths 6716, 6731 angstroms and [SIII] at 6312 angstroms and 9069, 9532 angstroms. For all of the observed galaxies, at least three ion-weighted temperatures from forbidden auroral to nebular line ratios have been obtained and the relations between the different line temperatures have been discussed. It is found that, for some objects, the [OII] temperatures derived from those of [OIII] through the use of photo-ionisation models, without taking into account the effect of density, can lead to a significant underestimate of the O+/H+ ionic abundance and hence of the total oxygen abundance.

  12. Beryllium abundance in turn-off stars of NGC 6752

    E-Print Network [OSTI]

    Luca Pasquini; Piercarlo Bonifacio; Sofia Randich; Daniele Galli; Raffaele G. Gratton; B. Wolff

    2006-12-27T23:59:59.000Z

    Aims: To measure the beryllium abundance in two TO stars of the Globular Cluster NGC 6752, one oxygen rich and sodium poor, the other presumably oxygen poor and sodium rich. Be abundances in these stars are used to put on firmer grounds the hypothesis of Be as cosmochronometer and to investigate the formation of Globular Clusters. Method:We present near UV spectra with resolution R$\\sim 45000$ obtained with the UVES spectrograph on the 8.2m VLT Kueyen telescope, analysed with spectrum synthesis based on plane parallel LTE model atmospheres. Results:Be is detected in the O rich star with log(Be/H)=-12.04 $\\pm$0.15, while Be is not detected in the other star for which we obtain the upper limit log(Be/H)$<$-12.2. A large difference in nitrogen abundance (1.6 dex) is found between the two stars. Conclusions:The Be measurement is compatible with what found in field stars with the same [Fe/H] and [O/H]. The 'Be age' of the cluster is found to be 13.3 Gyrs, in excellent agreement with the results from main sequence fitting and stellar evolution. The presence of Be confirms the results previously obtained for the cluster NGC 6397 and supports the hypothesis that Be can be used as a clock for the early formation of the Galaxy. Since only an upper limit is found for the star with low oxygen abundance, we cannot decide between competing scenarios of Globular Cluster formation, but we can exclude that 'polluted' stars are substantially younger than 'unpolluted' ones. We stress that the Be test might be the only measurement capable of distinguishing between these scenarios.

  13. Distribution and Abundance Patterns of Spiders Inhabiting Cotton in Texas.

    E-Print Network [OSTI]

    Dean, D.A.; Sterling, W.L.

    1987-01-01T23:59:59.000Z

    . L. Sterling Department of Entomology Texas A&M University Abstract Patterns of the distribution and abundance of spiders were determined in the major cotton growing areas of Texas during 1982-83. M isumenops spp., Oxyopes saiticus Hentz... to predict this neutrality is important since spiders could then be eliminated as an important factor in predicting the dynamics of other arthropods. The cotton fleahopper (Pseudatomoscelis seriatus [Reuter]) model (Hartstack and Sterling 1986) uses...

  14. Europium abundances in F and G disk dwarfs

    E-Print Network [OSTI]

    A. Koch; B. Edvardsson

    2001-11-06T23:59:59.000Z

    Europium abundances for 74 F and G dwarf stars of the galactic disk have been determined from the 4129.7 A Eu II line. The stars were selected from the sample of Edvardsson et al. (1993) and [Eu/Fe] shows a smaller scatter and a slightly weaker trend with [Fe/H] than found by Woolf et al. (1995). The data of the two analyses are homogenized and merged. We also discuss the adopted effective temperature scale.

  15. THE RAVE CATALOG OF STELLAR ELEMENTAL ABUNDANCES: FIRST DATA RELEASE

    SciTech Connect (OSTI)

    Boeche, C.; Williams, M.; De Jong, R. S.; Steinmetz, M. [Leibniz-Institut fuer Astrophysik Potsdam (AIP), D-14482 Potsdam (Germany); Siebert, A.; Bienayme, O. [Observatoire Astronomique de Strasbourg, Universite de Strasbourg, CNRS, UMR 7550, F-67000 Strasbourg (France); Fulbright, J. P.; Ruchti, G. R. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Bland-Hawthorn, J. [Sydney Institute for Astronomy, School of Physics A28, University of Sydney, NSW 2006 (Australia); Campbell, R. [Department of Physics and Astronomy, Western Kentucky University, Bowling Green, KY (United States); Freeman, K. C. [Research School of Astronomy and Astrophysics, Australia National University, Weston Creek, Canberra ACT 2611 (Australia); Gibson, B. K. [Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE (United Kingdom); Gilmore, G. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Grebel, E. K. [Astronomisches Rechen-Institut, Zentrum fuer Astronomie der Universitaet Heidelberg, D-69120 Heidelberg (Germany); Helmi, A. [Kapteyn Astronomical Institute, University of Groningen, 9700 AV Groningen (Netherlands); Munari, U. [INAF Osservatorio Astronomico di Padova, Asiago I-36012 (Italy); Navarro, J. F. [Department of Physics and Astronomy, University of Victoria, Victoria BC V8W 3P6 (Canada); Parker, Q. A.; Reid, W. [Department of Physics and Astronomy, Faculty of Sciences, Macquarie University, Sydney, NSW 2109 (Australia); Seabroke, G. M. [Mullard Space Science Laboratory, University College London, Holmbury, St. Mary RH5 6NT (United Kingdom); and others

    2011-12-15T23:59:59.000Z

    We present chemical elemental abundances for 36,561 stars observed by the RAdial Velocity Experiment (RAVE), an ambitious spectroscopic survey of our Galaxy at Galactic latitudes |b| > 25 Degree-Sign and with magnitudes in the range 9 abundances for the elements Mg, Al, Si, Ca, Ti, Fe, and Ni, with a mean error of {approx}0.2 dex, as judged from accuracy tests performed on synthetic and real spectra. Abundances are estimated through a dedicated processing pipeline in which the curve of growth of individual lines is obtained from a library of absorption line equivalent widths to construct a model spectrum that is then matched to the observed spectrum via a {chi}{sup 2} minimization technique. We plan to extend this pipeline to include estimates for other elements, such as oxygen and sulfur, in future data releases.

  16. CHAOS II: Gas-Phase Abundances in NGC 5194

    E-Print Network [OSTI]

    Croxall, Kevin V; Berg, Danielle; Skillman, Evan D; Moustakas, John

    2015-01-01T23:59:59.000Z

    We have observed NGC5194 (M51a) as part of the CHemical Abundances of Spirals (CHAOS) project. Using the Multi Object Double Spectrographs (MODS) on the Large Binocular Telescope (LBT) we are able to measure one or more of the temperature-sensitive auroral lines ([O III] 4363, [N II] 5755, [S III] 6312) and thus measure "direct" gas-phase abundances in 29 individual HII regions. [O III] 4363 is only detected in two HII regions both of which show indications of excitation by shocks. We compare our data to previous direct abundances measured in NGC5194 and find excellent agreement for all but one region (Delta[log(O/H)] ~ 0.04). We find no evidence of trends in Ar/O, Ne/O, or S/O within NGC5194 or compared to other galaxies. We find modest negative gradients in both O/H and N/O with very little scatter (sigma = -0.62) suggests secondary nitrogen production is responsible for a significantly larger fraction of nitrogen (e.g., factor of 8-10) relative to primary production mechanisms than predicted by theoretica...

  17. Lithium abundance in a sample of solar-like stars

    E-Print Network [OSTI]

    López-Valdivia, R; Bertone, E; Chávez, M; de Miera, F Cruz-Saenz; Amazo-Gómez, E M

    2015-01-01T23:59:59.000Z

    We report on the determination of the lithium abundance [A(Li)] of 52 solar-like stars. For 41 objects the A(Li) here presented corresponds to the first measurement. We have measured the equivalent widths of the 6708\\AA\\ lithium feature in high-resolution spectroscopic images ($R \\sim 80\\,000$), obtained at the Observatorio Astrof\\'isico Guillermo Haro (Sonora, Mexico), as part of the first scientific observations of the revitalized Lunar and Planetary Laboratory (LPL) Echelle Spectrograph, now known as the Cananea High-resolution Spectrograph (CanHiS). Lithium abundances were derived with the Fortran code MOOG, using as fundamental input a set of atmospheric parameters recently obtained by our group. With the help of an additional small sample with previous A(Li) determinations, we demonstrate that our lithium abundances are in agreement, to within uncertainties, with other works. Two target objects stand out from the rest of the sample. The star BD+47 3218 ($T_{\\rm eff}$ = 6050$\\pm$52 K, A(Li) = 1.86$\\pm$ 0...

  18. Oxygen abundance methods in the SDSS: view from modern statistics

    E-Print Network [OSTI]

    F. Shi; G. Zhao; James Wicker

    2007-10-24T23:59:59.000Z

    Our purpose is to find which is the most reliable one among various oxygen abundance determination methods. We will test the validity of several different oxygen abundance determination methods using methods of modern statistics. These methods include Bayesian analysis and information scoring. We will analyze a sample of $\\sim$6000 $\\hii$ galaxies from the Sloan Digital Sky Survey (SDSS) spectroscopic observations data release four. All methods that we used drew the same conclusion that the $T_e$ method is a more reliable oxygen abundance determination methods than the Bayesian metallcity method under the existing telescope ability. The ratios of the likelihoods between the different kinds of methods tell us that the $T_e$, $P$, and $O3N2$ methods are consistent with each other because the $P$ and $O3N2$ method are calibrated by $T_e$-method. The Bayesian and $R_{23}$ method are consistent with each other because both are calibrated by a galaxy model. In either case, the $N2$ method is an {\\it unreliable} method.

  19. CHEMICAL ABUNDANCE PATTERNS AND THE EARLY ENVIRONMENT OF DWARF GALAXIES

    SciTech Connect (OSTI)

    Corlies, Lauren; Johnston, Kathryn V.; Bryan, Greg [Department of Astronomy, Columbia University, New York, NY 10027 (United States); Tumlinson, Jason [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD (United States)

    2013-08-20T23:59:59.000Z

    Recent observations suggest that abundance pattern differences exist between low metallicity stars in the Milky Way stellar halo and those in the dwarf satellite galaxies. This paper takes a first look at what role the early environment for pre-galactic star formation might have played in shaping these stellar populations. In particular, we consider whether differences in cross-pollution between the progenitors of the stellar halo and the satellites could help to explain the differences in abundance patterns. Using an N-body simulation, we find that the progenitor halos of the main halo are primarily clustered together at z = 10 while the progenitors of the satellite galaxies remain on the outskirts of this cluster. Next, analytically modeled supernova-driven winds show that main halo progenitors cross-pollute each other more effectively while satellite galaxy progenitors remain more isolated. Thus, inhomogeneous cross-pollution as a result of different high-z spatial locations of each system's progenitors can help to explain observed differences in abundance patterns today. Conversely, these differences are a signature of the inhomogeneity of metal enrichment at early times.

  20. Record of Cycling Operation of the Natural Nuclear Reactor in the Oklo/Okelobondo Area in Gabon

    E-Print Network [OSTI]

    Record of Cycling Operation of the Natural Nuclear Reactor in the Oklo/Okelobondo Area in Gabon A billion yr old Oklo natural nuclear reactor. In addition to elevated abundances of fission-produced Zr, Ce nuclear chain reaction was predicted by Kuroda [1] 20 years before the remnants of the natural reactor

  1. Monash researchers led by Dr. Dan Li have developed a novel method for converting natural graphite into highly porous

    E-Print Network [OSTI]

    Albrecht, David

    natural graphite into highly porous graphene film for advanced applications. Figure 1: illustrates the conversion of inexpensive & abundant graphite into highly porous, mechanically robust conductive films (eg capacitors, batteries and fuel cells) n LCD displays and photovoltaic devices n Composites

  2. NATURAL GAS MARKET ASSESSMENT

    E-Print Network [OSTI]

    CALIFORNIA ENERGY COMMISSION NATURAL GAS MARKET ASSESSMENT PRELIMINARY RESULTS In Support.................................................................................... 6 Chapter 2: Natural Gas Demand.................................................................................................. 10 Chapter 3: Natural Gas Supply

  3. The Formation of the First Low-Mass Stars From Gas With Low Carbon and Oxygen Abundances

    E-Print Network [OSTI]

    Bromm, V; Bromm, Volker; Loeb, Abraham

    2003-01-01T23:59:59.000Z

    The first stars in the Universe are predicted to have been much more massive than the Sun. Gravitational condensation accompanied by cooling of the primordial gas due to molecular hydrogen, yields a minimum fragmentation scale of a few hundred solar masses. Numerical simulations indicate that once a gas clump acquires this mass, it undergoes a slow, quasi-hydrostatic contraction without further fragmentation. Here we show that as soon as the primordial gas - left over from the Big Bang - is enriched by supernovae to a carbon or oxygen abundance as small as ~0.01-0.1% of that found in the Sun, cooling by singly-ionized carbon or neutral oxygen can lead to the formation of low-mass stars. This mechanism naturally accommodates the discovery of solar mass stars with unusually low (10^{-5.3} of the solar value) iron abundance but with a high (10^{-1.3} solar) carbon abundance. The minimum stellar mass at early epochs is partially regulated by the temperature of the cosmic microwave background. The derived critical...

  4. Re-examining High Abundance SDSS Mass-Metallicity Outliers: High N/O, Evolved Wolf-Rayet Galaxies?

    E-Print Network [OSTI]

    Berg, Danielle A; Marble, Andrew R

    2011-01-01T23:59:59.000Z

    We present new MMT spectroscopic observations of four dwarf galaxies representative of a larger sample observed by the Sloan Digital Sky Survey (SDSS) and identified by Peeples et al. (2008) as low-mass, high oxygen abundance outliers from the mass-metallicity relation. Peeples et al. (2008) showed that these four objects (with metallicity estimates of 8.5 =~ 0.10), each of which tend to bias estimates based on strong emission lines toward high oxygen abundances. These spectra all fall in a regime where the "standard" strong line methods for metallicity determinations are not well calibrated either empirically or by photoionization modeling. By comparing our spectra directly to photoionization models, we estimate oxygen abundances in the range of 7.9 =< 12 + log(O/H) =< 8.4, consistent with the scatter of the mass-metallicity relation. We discuss the physical nature of these galaxies that leads to their unusual spectra (and previous classification as outliers), finding their low excitation, elevated N/O...

  5. Region-Specific Protein Abundance Changes in the Brain of MPTP...

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

    Region-Specific Protein Abundance Changes in the Brain of MPTP-induced Parkinson’s Disease Mouse Model . Region-Specific Protein Abundance Changes in the Brain of...

  6. Remarkable Amphibian Biomass and Abundance in an Isolated Wetland: Implications for Wetland

    E-Print Network [OSTI]

    Georgia, University of

    -1739.2006.00443.x #12;1458 Amphibian Biomass and Abundance Gibbons et al. Biomasa y Abundancia de Anfibios

  7. DIVERSITY OF TYPE Ia SUPERNOVAE IMPRINTED IN CHEMICAL ABUNDANCES

    SciTech Connect (OSTI)

    Tsujimoto, Takuji [National Astronomical Observatory of Japan, Mitaka-shi, Tokyo 181-8588 (Japan); Shigeyama, Toshikazu, E-mail: taku.tsujimoto@nao.ac.jp [Research Center for the Early Universe, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2012-12-01T23:59:59.000Z

    A time delay of Type Ia supernova (SN Ia) explosions hinders the imprint of their nucleosynthesis on stellar abundances. However, some occasional cases give birth to stars that avoid enrichment of their chemical compositions by massive stars and thereby exhibit an SN-Ia-like elemental feature including a very low [Mg/Fe] ( Almost-Equal-To - 1). We highlight the elemental feature of Fe-group elements for two low-Mg/Fe objects detected in nearby galaxies, and propose the presence of a class of SNe Ia that yield the low abundance ratios of [Cr, Mn, Ni/Fe]. Our novel models of chemical evolution reveal that our proposed class of SNe Ia (slow SNe Ia) is associated with ones exploding on a long timescale after their stellar birth and give a significant impact on the chemical enrichment in the Large Magellanic Cloud (LMC). In the Galaxy, on the other hand, this effect is unseen due to the overwhelming enrichment by the major class of SNe Ia that explode promptly (prompt SNe Ia) and eject a large amount of Fe-group elements. This nicely explains the different [Cr, Mn, Ni/Fe] features between the two galaxies as well as the puzzling feature seen in the LMC stars exhibiting very low Ca but normal Mg abundances. Furthermore, the corresponding channel of slow SN Ia is exemplified by performing detailed nucleosynthesis calculations in the scheme of SNe Ia resulting from a 0.8 + 0.6 M{sub Sun} white dwarf merger.

  8. Abundances of metal-weak thick-disc candidates

    E-Print Network [OSTI]

    P. Bonifacio; M. Centurion; P. Molaro

    1999-06-03T23:59:59.000Z

    High resolution spectra of 5 candidate metal-weak thick-disc stars suggested by Beers & Sommer-Larsen (1995) are analyzed to determine their chemical abundances. The low abundance of all the objects has been confirmed with metallicity reaching [Fe/H]=-2.9. However, for three objects, the astrometric data from the Hipparcos catalogue suggests they are true halo members. The remaining two, for which proper-motion data are not available, may have disc-like kinematics. It is therefore clear that it is useful to address properties of putative metal-weak thick-disc stars only if they possess full kinematic data. For CS 22894-19 the abundance pattern similar to those of typical halo stars is found, suggesting that chemical composition is not a useful discriminant between thick-disc and halo stars. CS 29529-12 is found to be C enhanced with [C/Fe]=+1.0; other chemical peculiarities involve the s process elements: [Sr/Fe]=-0.65 and [Ba/Fe]=+0.62, leading to a high [Ba/Sr] considerably larger than what is found in more metal-rich carbon-rich stars, but similar to LP 706-7 and LP 625-44 discussed by Norris et al (1997a). Hipparcos data have been used to calculate the space velocities of 25 candidate metal-weak thick-disc stars, thus allowing us to identify 3 bona fide members, which support the existence of a metal-poor tail of the thick-disc, at variance with a claim to the contrary by Ryan & Lambert (1995).

  9. MANGANESE ABUNDANCES IN THE GLOBULAR CLUSTER {omega} CENTAURI

    SciTech Connect (OSTI)

    Cunha, Katia; Smith, Verne V. [National Optical Astronomy Observatory, 950 N. Cherry Avenue, Tucson, AZ, 85719 (United States); Bergemann, Maria [Max-Planck Institute for Astrophysics, Karl-Schwarzschild Str. 1, 85741 Garching (Germany); Suntzeff, Nicholas B. [Department of Physics and Astronomy and Mitchell Institute for Fundamental Physics and Astronomy, Texas A and M University, College Station, TX 77843-4242 (United States); Lambert, David L. [University of Texas, 1 University Station, C1400, Austin, TX 78712 (United States)

    2010-07-01T23:59:59.000Z

    We present manganese abundances in 10 red giant members of the globular cluster {omega} Centauri; eight stars are from the most metal-poor population (RGB MP and RGB MInt1) while two targets are members of the more metal-rich groups (RGB MInt2 and MInt3). This is the first time Mn abundances have been studied in this peculiar stellar system. The LTE values of [Mn/Fe] in {omega} Cen overlap those of Milky Way stars in the metal-poor {omega} Cen populations ([Fe/H] {approx}-1.5 to -1.8), however unlike what is observed in Milky Way halo and disk stars, [Mn/Fe] declines in the two more metal-rich RGB MInt2 and MInt3 targets. Non-LTE calculations were carried out in order to derive corrections to the LTE Mn abundances. The non-LTE results for {omega} Cen in comparison with the non-LTE [Mn/Fe] versus [Fe/H] trend obtained for the Milky Way confirm and strengthen the conclusion that the manganese behavior in {omega} Cen is distinct. These results suggest that low-metallicity supernovae (with metallicities {<=} -2) of either Type II or Type Ia dominated the enrichment of the more metal-rich stars in {omega} Cen. The dominance of low-metallicity stars in the chemical evolution of {omega} Cen has been noted previously in the s-process elements where enrichment from metal-poor asymptotic giant branch stars is indicated. In addition, copper, which also has metallicity-dependent yields, exhibits lower values of [Cu/Fe] in the RGB MInt2 and MInt3 {omega} Cen populations.

  10. Abundance profile and stellar content of IZw18

    E-Print Network [OSTI]

    F. Legrand

    1997-12-08T23:59:59.000Z

    New spectroscopic observations of the metal poor galaxy IZw 18 are discussed. Wolf-Rayet stars of WC type have been detected in the NW-HII region contrary to evolutionary synthesis model predictions. Implications on the mass loss rate and on the formation processes of WR stars are discussed. A very homogeneous metal abundance is observed within the HII region. This emphasizes the problem of the dispersal and mixing of new synthesized element in a starburst. Different scenarios are discussed, showing that metals remain most likely hidden in a hot phase and that the observed present metallicity is the result of a previous star formation event.

  11. Non-LTE Abundances of Magnesium, Aluminum and Sulfur in OB Stars Near the Solar Circle

    E-Print Network [OSTI]

    S. Daflon; K. Cunha; V. V. Smith; K. Butler

    2002-12-09T23:59:59.000Z

    Non-LTE abundances of magnesium, aluminum and sulfur are derived for a sample of 23 low-v \\sin i stars belonging to six northern OB associations of the Galactic disk within 1 kpc of the Sun. The abundances are obtained from the fitting of synthetic line profiles to high resolution spectra. A comparison of our results with HII region abundances indicates good agreement for sulfur while the cepheid abundances are higher. The derived abundances of Mg show good overlap with the cepheid results. The aluminum abundances for OB stars are significantly below the cepheid values. But, the OB star results show a dependence with effective temperature and need further investigation. The high Al abundances in the cepheids could be the result of mixing. A discussion of the oxygen abundance in objects near the solar circle suggests that the current mean galactic oxygen abundance in this region is 8.6-8.7 and in agreement with the recently revised oxygen abundance in the solar photosphere. Meaningful comparisons of the absolute S, Al and Mg abundances in OB stars with the Sun must await a reinvestigation of these elements, as well as the meteoritic reference element Si, with 3D hydrodynamical model atmospheres for the Sun. No abundance gradients are found within the limited range in galactocentric distances in the present study. Such variations would be expected only if there were large metallicity gradients in the disk.

  12. Abundances of Vanadium and Bromine in 3 Cen A: Additional Odd-Z Anomalies

    E-Print Network [OSTI]

    C. R. Cowley; G. M. Wahlgren

    2005-12-12T23:59:59.000Z

    We report abundance excesses of 1.2 and 2.6 dex, respectively, for vanadium and bromine in the hot, peculiar star 3 Cen A. Abundances for these two odd-Z elements have not been previously reported for this star. Taken with previous work, they strengthen the case of the origin of the abundance peculiarities by diffusion.

  13. OXYGEN GAS-PHASE ABUNDANCE REVISITED M. K. Andre,1,2

    E-Print Network [OSTI]

    Howk, Jay Christopher

    OXYGEN GAS-PHASE ABUNDANCE REVISITED M. K. Andre´,1,2 C. M. Oliveira,2 J. C. Howk,2 R. Ferlet,1 J gas-phase oxygen abundance along the sight lines toward 19 early-type Galactic stars at an average magÀ1 with a standard deviation of 15% is consistent with previous surveys. The mean oxygen abundance

  14. Discovery of interstellar ketenyl (HCCO), a surprisingly abundant radical

    E-Print Network [OSTI]

    Agundez, Marcelino; Guelin, Michel

    2015-01-01T23:59:59.000Z

    We have conducted radioastronomical observations of 9 dark clouds with the IRAM 30m telescope. We present the first identification in space of the ketenyl radical (HCCO) toward the starless core Lupus-1A and the molecular cloud L483, and the detection of the related molecules ketene (H2CCO) and acetaldehyde (CH3CHO) in these two sources and 3 additional dark clouds. We also report the detection of the formyl radical (HCO) in the 9 targeted sources and of propylene (CH2CHCH3) in 4 of the observed sources, which extends significantly the number of dark clouds where these molecules are known to be present. We derive a beam-averaged column density of HCCO of 5e11 cm-2 in both Lupus-1A and L483, which means that the ketenyl radical is just 10 times less abundant than ketene in these sources. The non-negligible abundance of HCCO found implies that there must be a powerful formation mechanism able to counterbalance the efficient destruction of this radical through reactions with neutral atoms. The column densities d...

  15. Diversity of Type Ia Supernovae Imprinted in Chemical Abundances

    E-Print Network [OSTI]

    Tsujimoto, Takuji

    2012-01-01T23:59:59.000Z

    A time delay of Type Ia supernova (SN Ia) explosions hinders the imprint of their nucleosynthesis on stellar abundances. However, some occasional cases give birth to stars that avoid enrichment of their chemical compositions by massive stars and thereby exhibit a SN Ia-like elemental feature including a very low [Mg/Fe] (~-1). We highlight the elemental feature of Fe-group elements for two low-Mg/Fe objects detected in nearby galaxies, and propose the presence of a class of SNe Ia that yield the low abundance ratios of [Cr,Mn,Ni/Fe]. Our novel models of chemical evolution reveal that our proposed class of SNe Ia (slow SNe Ia) is associated with ones exploding on a long timescale after their stellar birth, and gives a significant impact on the chemical enrichment in the Large Magellanic Cloud (LMC). In the Galaxy, on the other hand, this effect is unseen due to the overwhelming enrichment by the major class of SNe Ia that explode promptly (prompt SNe Ia) and eject a large amount of Fe-group elements. This nice...

  16. Elemental Abundances from Intrinsic QSO Emission and Absorption Lines

    E-Print Network [OSTI]

    F. Hamann

    1998-06-06T23:59:59.000Z

    Several studies have shown that the column densities inferred from broad absorption lines (BALs) require extremely high metallicities and phosphorus overabundances -- apparently in conflict with other abundance diagnostics. Here I use HST spectroscopy of the BALQSO PG 1254+047 to argue that the BALs abundance estimates are incorrect, because partial line-of-sight coverage of the continuum source(s) has led to gross underestimates of the line optical depths and column densities. I claim that the significant presence of PV 1118,1128 absorption in this and other BALQSOs identifies the saturated absorption-line spectrum. This interpretation implies that the total column densities are at least ten times larger than previous estimates, namely log N_H(cm-2) > 22. The outflowing BAL gas, at velocities from -15,000 to -27,000 km/s in PG 1254+047, is therefore a strong candidate for the X-ray absorber in BALQSOs. If this high-column density outflow is radiately accelerated, it must originate <0.1 pc from the QSO.

  17. The element abundance FIP effect in the quiet Sun

    E-Print Network [OSTI]

    P. R. Young

    2005-03-02T23:59:59.000Z

    The Mg/Ne abundance ratio in the quiet Sun is measured in both network and supergranule cell centre regions through EUV spectra from the Coronal Diagnostic Spectrometer on SOHO. Twenty four sets of data over the period 1996 March to 1998 June (corresponding to solar minimum) are studied. Emission lines of the sequences Ne IV-VII and Mg V-VIII are simultaneously analysed by comparing with theoretical emissivities from the CHIANTI database to yield the Mg/Ne abundance and emission measure over the temperature region 5.0 Sun connects into the solar wind. The quiet Sun spectra are also utilised to determine the coronal density and temperature, leading to average values of 2.6^+0.5_-0.4 x 10^8 cm^-3 and log (T/K)=5.95 +/- 0.02. No significant trend with the rise in solar activity during 1996--98 is found for any of the derived quantities, implying that quiet Sun regions show little dependence on the solar cycle.

  18. Lithium abundances in exoplanet-host stars : modelling

    E-Print Network [OSTI]

    M. Castro; S. Vauclair; O. Richard; N. C. Santos

    2008-11-18T23:59:59.000Z

    Aims. Exoplanet-host stars (EHS) are known to present superficial chemical abundances different from those of stars without any detected planet (NEHS). EHS are, on the average, overmetallic compared to the Sun. The observations also show that, for cool stars, lithium is more depleted in EHS than in NEHS. The aim of this paper is to obtain constraints on possible models able to explain this difference, in the framework of overmetallic models compared to models with solar abundances. Methods. We have computed main sequence stellar models with various masses and metallicities. The results show different behaviour for the lithium destruction according to those parameters. We compare these results to the spectroscopic observations of lithium. Results. Our models show that the observed lithium differences between EHS and NEHS are not directly due to the overmetallicity of the EHS: some extra mixing is needed below the convective zones. We discuss possible explanations for the needed extra mixing, in particular an increase of the mixing efficiency associated with the development of shear instabilities below the convective zone, triggered by angular momentum transfer due to the planetary migration.

  19. HNCO abundances in galaxies: Tracing the evolutionary state of starbursts

    E-Print Network [OSTI]

    Sergio Martin; J. Martin-Pintado; R. Mauersberger

    2008-12-19T23:59:59.000Z

    The chemistry in the central regions of galaxies is expected to be strongly influenced by their nuclear activity. To find the best tracers of nuclear activity is of key importance to understand the processes taking place in the most obscured regions of galactic nuclei. In this work we present multi-line observations of CS, C34S, HNCO and C18O in a sample of 11 bright galaxies prototypical for different types of activity. The 32S/34S isotopic ratio is ~10, supporting the idea of an isotopical 34S enrichment due to massive star formation in the nuclear regions of galaxies. Although C32S and C34S do not seem to be significantly affected by the activity type, the HNCO abundance appears highly contrasted among starburst. We observed HNCO abundance variations of nearly two orders of magnitude. The HNCO molecule is shown to be a good tracer of the amount of molecular material fueling the starburst and therefore can be used as a diagnostics of the evolutionary state of a nuclear starburst.

  20. Zirconium, Barium, Lanthanum and Europium Abundances in Open Clusters

    E-Print Network [OSTI]

    Jacobson, H R; 10.1088/0004-6256/145/4/107

    2013-01-01T23:59:59.000Z

    We present an analysis of the s-process elements Zr, Ba, and La and the r-process element Eu in a sample of 50 stars in 19 open clusters. Stellar abundances of each element are based on measures of a minimum of two lines per species via both equivalent width and spectrum synthesis techniques. We investigate cluster mean neutron-capture abundance trends as a function of cluster age and location in the Milky Way disk and compare them to results found in other studies in the literature. We find a statistically significant trend of increasing cluster [Ba/Fe] as a function of decreasing cluster age, in agreement with recent findings for other open cluster samples, supporting the increased importance of low-mass asymptotic giant branch stars to the generation of s-process elements. However, the other s-process elements, [La/Fe] and [Zr/Fe], do not show similar dependences, in contrast to theoretical expectations and the limited observational data from other studies. Conversely, cluster [Eu/Fe] ratios show a slight ...

  1. Carbon stars in local group dwarf galaxies: C and O abundances

    E-Print Network [OSTI]

    R. Wahlin; K. Eriksson; B. Gustafsson; K. H. Hinkle; D. L. Lambert; N. Ryde; B. Westerlund

    2006-05-10T23:59:59.000Z

    We present abundances of carbon and oxygen as well as abundance ratios 12C/13C for a sample of carbon stars in the LMC, SMC, Carina, Sculptor and Fornax dwarf galaxies. The overall metallicities in these dwarf galaxies are lower than in the galactic disc. The observations cover most of the AGB and we discuss the abundance patterns in different regions along the AGB. The abundances are determined from infrared spectra obtained with the ISAAC spectrometer on VLT (R=1500) and the Phoenix Spectrometer on Gemini South (R=50000). The synthetic spectra used in the analysis were computed with MARCS model atmospheres. We find that the oxygen abundance is decreasing with decreasing overall metallicity of the system while the C/O ratio at a given evolutionary phase is increasing with decreasing oxygen abundance. keywords Stars: abundances -- Stars: carbon -- Stars: AGB and post-AGB -- Galaxies: dwarf -- Local Group -- Infrared: stars

  2. arboreal ant abundance: Topics by E-print Network

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

    for the split (more) Rajappa, Gautham Puttur 2012-01-01 273 Proceedings of the 9th Conference on Computational Natural Language Learning (CoNLL), pages 165168, Ann...

  3. Tools and Technology Article Assessing Estimators of Snow Leopard Abundance

    E-Print Network [OSTI]

    Schweik, Charles M.

    Community Business Forum, per. Pozharskogo d. 1 Bishkek, 720035, Kyrgyzstan ABSTRACT The secretive nature of Kyrgyzstan and China. During June­December 2005, adjusted sign averaged 46.3 (SaryChat), 94.6 (Jangart

  4. Planning Amid Abundance: Alaska’s FY 2013 Budget Process

    E-Print Network [OSTI]

    McBeath, Jerry

    2013-01-01T23:59:59.000Z

    on liquefied natural gas (LNG). He met with the Alaska CEOsof the companies’ position on LNG exports with the state’s (unclear whether a large LNG project would be feasible and

  5. Commissioning of a magnetic suspension densitometer for high-accuracy density measurements of natural gas mixtures

    E-Print Network [OSTI]

    Patil, Prashant Vithal

    2009-05-15T23:59:59.000Z

    of developing clean coal technology and its abundant, economical domestic sources made coal the focus of attention once again (Ferguson, 2002). The US DOE in conjunction with the industry initiated a research, development and demonstration (RD&D) program...). Until clean coal technologies mature to compete viably with natural gas, production of natural gas must be maintained or increased to avoid dependence upon imported petroleum oil. Although natural gas and coal may appear to rival each other in the mid...

  6. Regulation of natural monopolies

    E-Print Network [OSTI]

    Joskow, Paul L.

    2005-01-01T23:59:59.000Z

    This chapter provides a comprehensive overview of the theoretical and empirical literature on the regulation of natural monopolies. It covers alternative definitions of natural monopoly, regulatory goals, alternative ...

  7. Natural Gas Monthly Update

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

    other liquids including biofuels and natural gas liquids. Natural Gas Exploration and reserves, storage, imports and exports, production, prices, sales. Electricity Sales, revenue...

  8. Borrowing Nature's Polymers

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

    Borrowing Nature's Polymers 1663 Los Alamos science and technology magazine Latest Issue:January 2015 All Issues submit Borrowing Nature's Polymers Los Alamos scientists are...

  9. Natural Resources Districts (Nebraska)

    Broader source: Energy.gov [DOE]

    This statute establishes Natural Resources District, encompassing all of the area of the state, to conserve, protect, develop, and manage Nebraska's natural resources. These districts replace and...

  10. Historical Natural Gas Annual

    U.S. Energy Information Administration (EIA) Indexed Site

    8 The Historical Natural Gas Annual contains historical information on supply and disposition of natural gas at the national, regional, and State level as well as prices at...

  11. Natural Gas Rules (Louisiana)

    Broader source: Energy.gov [DOE]

    The Louisiana Department of Natural Resources administers the rules that govern natural gas exploration and extraction in the state. DNR works with the Louisiana Department of Environmental...

  12. Historical Natural Gas Annual

    U.S. Energy Information Administration (EIA) Indexed Site

    6 The Historical Natural Gas Annual contains historical information on supply and disposition of natural gas at the national, regional, and State level as well as prices at...

  13. Historical Natural Gas Annual

    U.S. Energy Information Administration (EIA) Indexed Site

    7 The Historical Natural Gas Annual contains historical information on supply and disposition of natural gas at the national, regional, and State level as well as prices at...

  14. An empirical calibration of nebular abundances based on the sulphur emission lines

    E-Print Network [OSTI]

    A. I. Diaz; E. Perez-Montero

    1999-09-29T23:59:59.000Z

    We present an empirical calibration of nebular abundances based on the strong emission lines of [SII] and [SIII] in the red part of the spectrum through the definition of a sulphur abundance parameter S23. This calibration presents two important advantages against the commonly used one based on the optical oxygen lines: it remains single-valued up to abundances close to solar and is rather independent of the degree of ionization of the nebula.

  15. Parent Stars of Extrasolar Planets. VIII. Chemical Abundances for 18 Elements in 31 Stars

    E-Print Network [OSTI]

    Guillermo Gonzalez; Chris Laws

    2007-04-17T23:59:59.000Z

    We present the results of detailed spectroscopic abundance analyses for 18 elements in 31 nearby stars with planets. The resulting abundances are combined with other similar studies of nearby stars with planets and compared to a sample of nearby stars without detected planets. We find some evidence for abundance differences between these two samples for Al, Si and Ti. Some of our results are in conflict with a recent study of stars with planets in the SPOCS database. We encourage continued study of the abundance patterns of stars with planets to resolve these discrepancies.

  16. Remarkable Amphibian Biomass and Abundance in an Isolated Wetland: Implications for Wetland

    E-Print Network [OSTI]

    Todd, Brian

    DOI: 10.1111/j.1523-1739.2006.00443.x #12;2 Amphibian Biomass and Abundance Gibbons et al. Biomasa y

  17. Life History, Abundance, and Distribution of the Spotted Ratfish, Hydrolagus colliei

    E-Print Network [OSTI]

    Barnett, Lewis A.K.

    2008-01-01T23:59:59.000Z

    captive H. colliei, taken from Puget Sound, WA, deposited 18most abundant groundfish in Puget Sound, Washington (Palssonand diel migrations in Puget Sound. If these behaviors are

  18. The Relative Abundance of Desert Tortoises on the Nevada Test Site within Ecological Landform Units

    SciTech Connect (OSTI)

    Roy Woodward, Kurt R. Rautenstrauch, Derek B. Hall, and W. Kent Ostler

    1998-09-01T23:59:59.000Z

    Sign-survey transects were sampled in 1996 to better determine the relative abundance of desert tortoises on the Nevada Test Site (NTS). These transects were sampled within ecological land-form units (ELUs), which are small, ecologically homogeneous units of land. Two-hundred and six ELUs were sampled by walking 332 transects totaling 889 kilometers (km) (552 miles [mi]). These ELUs covered 528 km{sup 2} (204 mi{sup 2}). Two-hundred and eighty-one sign were counted. An average of 0.32 sign was found per km walked. Seventy percent of the area sampled had a very low abundance of tortoises, 29 percent had a low abundance, and 1 percent had a moderate abundance. A revised map of the relative abundance of desert tortoise on the NTS is presented. Within the 1,330 km{sup 2} (514 mi{sup 2}) of desert tortoise habitat on the NTS, 49 percent is classified as having no tortoises or a very low abundance, 18 percent has a low or moderate abundance, 12 percent is unclassified land being used by the Yucca Mountain Site Characterization Project, and the remaining 21 percent still has an unknown abundance of desert tortoises. Based on the results of this work, the amount of tortoise habitat previously classified as having an unknown or low-moderate abundance, and on which clearance surveys and on-site monitoring was required, has been reduced by 20 percent.

  19. The relative abundance of desert tortoises on the Nevada Test Site within ecological landform units

    SciTech Connect (OSTI)

    Woodward, R. [Bechtel National (United States); Rautenstrauch, K.R. [Science Applications International Corp. (United States); Hall, D.B.; Ostler, W.K. [Bechtel Nevada (United States)

    1998-09-01T23:59:59.000Z

    Sign-survey transects were sampled in 1996 to better determine the relative abundance of desert tortoises on the Nevada Test Site (NTS). These transects were sampled within ecological land-form units (ELUs), which are small, ecologically homogeneous units of land. Two-hundred and six ELUs were sampled by walking 332 transects totaling 889 kilometers (km). These ELUs covered 528 km{sup 2}. Two-hundred and eight-one sign were counted. An average of 0.32 sign was found per km walked. Seventy percent of the area sampled had a very low abundance of tortoises, 29% had a low abundance, and 1% had a moderate abundance. A revised map of the relative abundance of desert tortoise on the NTS is presented. Within the 1,330 km{sup 2} of desert tortoise habitat on the NTS, 49% is classified as having no tortoises or a very low abundance, 18% has a low or moderate abundance, 12% is unclassified land being used by the Yucca Mountain Site Characterization Project, and the remaining 21% still has an unknown abundance of desert tortoises. Based on the results of this work, the amount of tortoise habitat previously classified as having an unknown or low-moderate abundance, and on which clearance surveys and on-site monitoring was required, has been reduced by 20%.

  20. A MASS-DEPENDENT YIELD ORIGIN OF NEUTRON-CAPTURE ELEMENT ABUNDANCE DISTRIBUTIONS IN ULTRA-FAINT DWARFS

    SciTech Connect (OSTI)

    Lee, Duane M.; Johnston, Kathryn V. [Department of Astronomy, Columbia University, New York City, NY 10027 (United States); Tumlinson, Jason [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Sen, Bodhisattva [Department of Statistics, Columbia University, New York City, NY 10027 (United States); Simon, Joshua D. [The Observatories of the Carnegie Institution of Washington, Pasadena, CA 91101 (United States)

    2013-09-10T23:59:59.000Z

    One way to constrain the nature of the high-redshift progenitors of the Milky Way (MW) is to look at the low-metallicity stellar populations of the different Galactic components today. For example, high-resolution spectroscopy of very metal poor (VMP) stars demonstrates remarkable agreement between the distribution of [Ti/Fe] in the stellar populations of the MW halo and ultra-faint dwarf (UFD) galaxies. In contrast, for the neutron-capture (nc) abundance ratio distributions [(Sr, Ba)/Fe], the peak of the small UFD sample (6 stars) exhibits a significant under-abundance relative to the VMP stars in the larger MW halo sample ({approx}300 stars). We present a simple scenario that can simultaneously explain these similarities and differences by assuming: (1) that the MW VMP stars were predominately enriched by a prior generation of stars which possessed a higher total mass than the prior generation of stars that enriched the UFD VMP stars; and (2) a much stronger mass-dependent yield (MDY) for nc-elements than for the (known) MDY for Ti. Simple statistical tests demonstrate that conditions (1) and (2) are consistent with the observed abundance distributions, albeit without strong constraints on model parameters. A comparison of the broad constraints for these nc-MDY with those derived in the literature seems to rule out Ba production from low-mass supernovae (SNe) and affirms models that primarily generate yields from high-mass SNe. Our scenario can be confirmed by a relatively modest (factor of {approx}3-4) increase in the number of high-resolution spectra of VMP stars in UFDs.

  1. Natural Gas Exploration

    E-Print Network [OSTI]

    Boyer, Elizabeth W.

    . Exploration and extraction of natural gas from the Marcellus shale is a potentially valuable economic stimulus for landowners. You might be wondering how the nation's economic situation is affecting the market for naturalNatural Gas Exploration: A Landowners Guide to Financial Management Natural Gas Exploration

  2. Research Highlights Nature Nanotechnology

    E-Print Network [OSTI]

    Müller, Markus

    © 2009 APS Research Highlights Nature Nanotechnology Published online: 17 July 2009 | doi:10 perfect fluid. Phys. Rev. Lett. 103, 025301 (2009). | Article |1. Nature Nanotechnology ISSN 1748 : Nature Nanotechnology http://www.nature.com/nnano/reshigh/2009/0709/full/nnano.2009.222.html 1 of 1 18

  3. Low 60Fe abundance in Semarkona and Sahara 99555

    E-Print Network [OSTI]

    Tang, Haolan

    2015-01-01T23:59:59.000Z

    Iron-60 (t1/2=2.62 Myr) is a short-lived nuclide that can help constrain the astrophysical context of solar system formation and date early solar system events. A high abundance of 60Fe (60Fe/56Fe= 4x10-7) was reported by in situ techniques in some chondrules from the LL3.00 Semarkona meteorite, which was taken as evidence that a supernova exploded in the vicinity of the birthplace of the Sun. However, our previous MC-ICPMS measurements of a wide range of meteoritic materials, including chondrules, showed that 60Fe was present in the early solar system at a much lower level (60Fe/56Fe=10-8). The reason for the discrepancy is unknown but only two Semarkona chondrules were measured by MC-ICPMS and these had Fe/Ni ratios below ~2x chondritic. Here, we show that the initial 60Fe/56Fe ratio in Semarkona chondrules with Fe/Ni ratios up to ~24x chondritic is 5.4x10-9. We also establish the initial 60Fe/56Fe ratio at the time of crystallization of the Sahara 99555 angrite, a chronological anchor, to be 1.97x10-9. The...

  4. Molecular hydrogen abundances of galaxies in the EAGLE simulations

    E-Print Network [OSTI]

    Lagos, Claudia del P; Schaye, Joop; Furlong, Michelle; Frenk, Carlos S; Bower, Richard G; Schaller, Matthieu; Theuns, Tom; Trayford, James W; Bahe, Yannick M; Vecchia, Claudio Dalla

    2015-01-01T23:59:59.000Z

    We investigate the abundance of galactic molecular hydrogen (H$_2$) in the "Evolution and Assembly of GaLaxies and their Environments" (EAGLE) cosmological hydrodynamic simulations. We assign H$_2$ masses to gas particles in the simulations in post-processing using two different prescriptions that depend on the local dust-to-gas ratio and the interstellar radiation field. Both result in H$_2$ galaxy mass functions that agree well with observations in the local and high-redshift Universe. The simulations reproduce the observed scaling relations between the mass of H$_2$ and the stellar mass, star formation rate and stellar surface density. Towards high edshifts, galaxies in the simulations display larger H$_2$ mass fractions, and correspondingly lower H$_2$ depletion timescales, also in good agreement with observations. The comoving mass density of H$_2$ in units of the critical density, $\\Omega_{\\rm H_2}$, peaks at $z\\approx 1.2-1.5$, later than the predicted peak of the cosmic star formation rate activity, a...

  5. LARGE ABUNDANCES OF POLYCYCLIC AROMATIC HYDROCARBONS IN TITAN'S UPPER ATMOSPHERE

    SciTech Connect (OSTI)

    Lopez-Puertas, M.; Funke, B.; Garcia-Comas, M. [Instituto de Astrofisica de Andalucia (CSIC), E-18080 Granada (Spain); Dinelli, B. M. [ISAC-CNR, I-40129 Bologna (Italy); Adriani, A.; D'Aversa, E. [IAPS-INAF, I-00133 Rome (Italy); Moriconi, M. L. [ISAC-CNR, I-00133 Rome (Italy); Boersma, C.; Allamandola, L. J., E-mail: puertas@iaa.es [NASA Ames Research Center, Moffett Field, CA 94035-1000 (United States)

    2013-06-20T23:59:59.000Z

    In this paper, we analyze the strong unidentified emission near 3.28 {mu}m in Titan's upper daytime atmosphere recently discovered by Dinelli et al. We have studied it by using the NASA Ames PAH IR Spectroscopic Database. The polycyclic aromatic hydrocarbons (PAHs), after absorbing UV solar radiation, are able to emit strongly near 3.3 {mu}m. By using current models for the redistribution of the absorbed UV energy, we have explained the observed spectral feature and have derived the vertical distribution of PAH abundances in Titan's upper atmosphere. PAHs have been found to be present in large concentrations, about (2-3) Multiplication-Sign 10{sup 4} particles cm{sup -3}. The identified PAHs have 9-96 carbons, with a concentration-weighted average of 34 carbons. The mean mass is {approx}430 u; the mean area is about 0.53 nm{sup 2}; they are formed by 10-11 rings on average, and about one-third of them contain nitrogen atoms. Recently, benzene together with light aromatic species as well as small concentrations of heavy positive and negative ions have been detected in Titan's upper atmosphere. We suggest that the large concentrations of PAHs found here are the neutral counterpart of those positive and negative ions, which hence supports the theory that the origin of Titan main haze layer is located in the upper atmosphere.

  6. The Water Vapor Abundance in Orion KL Outflows

    E-Print Network [OSTI]

    J. Cernicharo; J. R. Goicoechea; F. Daniel; M. R. Lerate; M. J. Barlow; B. M. Swinyard; E. van Dishoeck; T. L. Lim; S. Viti; J. Yates

    2006-08-16T23:59:59.000Z

    We present the detection and modeling of more than 70 far-IR pure rotational lines of water vapor, including the 18O and 17O isotopologues, towards Orion KL. Observations were performed with the Long Wavelength Spectrometer Fabry-Perot (LWS/FP; R~6800-9700) on board the Infrared Space Observatory (ISO) between ~43 and ~197 um. The water line profiles evolve from P-Cygni type profiles (even for the H2O18 lines) to pure emission at wavelengths above ~100 um. We find that most of the water emission/absorption arises from an extended flow of gas expanding at 25+-5 kms^-1. Non-local radiative transfer models show that much of the water excitation and line profile formation is driven by the dust continuum emission. The derived beam averaged water abundance is 2-3x10^-5. The inferred gas temperature Tk=80-100 K suggests that: (i) water could have been formed in the "plateau" by gas phase neutral-neutral reactions with activation barriers if the gas was previously heated (e.g. by shocks) to >500 K and/or (ii) H2O formation in the outflow is dominated by in-situ evaporation of grain water-ice mantles and/or (iii) H2O was formed in the innermost and warmer regions (e.g. the hot core) and was swept up in ~1000 yr, the dynamical timescale of the outflow.

  7. Germanium abundances in lunar basalts: Evidence of mantle metasomatism

    SciTech Connect (OSTI)

    Dickinson, T.; Taylor, G.J.; Keil, T.K.; Bild, R.W.

    1988-01-01T23:59:59.000Z

    To fill in gaps in the present Ge data base, mare basalts were analyzed for Ge and other elements by RNAA and INAA. Mare basalts from Apollo 11, 12, 15, 17 landing sites are rather uniform in Ge abundance, but Apollo 14 aluminous mare basalts and KREEP are enriched in Ge by factors of up to 300 compared to typical mare basalts. These Ge enrichments are not associated with other siderophile element enrichments and, thus, are not due to differences in the amount of metal segregated during core formation. Based on crystal-chemical and inter-element variations, it does not appear that the observed Ge enrichments are due to silicate liquid immiscibility. Elemental ratios in Apollo 14 aluminous mare basalts, green and orange glass, average basalts and KREEP suggest that incorporation of late accreting material into the source regions or interaction of the magmas with primitive undifferentiated material is not a likely cause for the observed Ge enrichments. We speculate that the most plausible explanation for these Ge enrichments is complexing and concentration of Ge by F, Cl or S in volatile phases. In this manner, the KREEP basalt source regions may have been metasomatized and Apollo 14 aluminous mare basalt magmas may have become enriched in Ge by interacting with these metasomatized areas. The presence of volatile- and Ge-rich regions in the Moon suggests that the Moon was never totally molten. 71 refs., 1 fig., 6 tabs.

  8. Natural gas monthly

    SciTech Connect (OSTI)

    NONE

    1998-01-01T23:59:59.000Z

    The Natural Gas Monthly highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the Natural Gas Monthly features articles designed to assist readers in using and interpreting natural gas information.

  9. ANALYSIS OF RICIN TOXIN PREPARATIONS FOR CARBOHYDRATE AND FATTY ACID ABUNDANCE AND ISOTOPE RATIO INFORMATION

    SciTech Connect (OSTI)

    Wunschel, David S.; Kreuzer-Martin, Helen W.; Antolick, Kathryn C.; Colburn, Heather A.; Moran, James J.; Melville, Angela M.

    2009-12-01T23:59:59.000Z

    This report describes method development and preliminary evaluation for analyzing castor samples for signatures of purifying ricin. Ricin purification from the source castor seeds is essentially a problem of protein purification using common biochemical methods. Indications of protein purification will likely manifest themselves as removal of the non-protein fractions of the seed. Two major, non-protein, types of biochemical constituents in the seed are the castor oil and various carbohydrates. The oil comprises roughly half the seed weight while the carbohydrate component comprises roughly half of the remaining “mash” left after oil and hull removal. Different castor oil and carbohydrate components can serve as indicators of specific toxin processing steps. Ricinoleic acid is a relatively unique fatty acid in nature and is the most abundant component of castor oil. The loss of ricinoleic acid indicates a step to remove oil from the seeds. The relative amounts of carbohydrates and carbohydrate-like compounds, including arabinose, xylose, myo-inositol fucose, rhamnose, glucosamine and mannose detected in the sample can also indicate specific processing steps. For instance, the differential loss of arabinose relative to mannose and N-acetyl glucosamine indicates enrichment for the protein fraction of the seed using protein precipitation. The methods developed in this project center on fatty acid and carbohydrate extraction from castor samples followed by derivatization to permit analysis by gas chromatography-mass spectrometry (GC-MS). Method descriptions herein include: the source and preparation of castor materials used for method evaluation, the equipment and description of procedure required for chemical derivatization, and the instrument parameters used in the analysis. Two types of derivatization methods describe analysis of carbohydrates and one procedure for analysis of fatty acids. Two types of GC-MS analysis is included in the method development, one employing a quadrupole MS system for compound identification and an isotope ratio MS for measuring the stable isotope ratios of deuterium and hydrogen (D/H) in fatty acids. Finally, the method for analyzing the compound abundance data is included. This study indicates that removal of ricinoleic acid is a conserved consequence of each processing step we tested. Furthermore, the stable isotope D/H ratio of ricinoleic acid distinguished between two of the three castor seed sources. Concentrations of arabinose, xylose, mannose, glucosamine and myo-inositol differentiated between crude or acetone extracted samples and samples produced by protein precipitation. Taken together these data illustrate the ability to distinguish between processes used to purify a ricin sample as well as potentially the source seeds.

  10. THE CORONAL ABUNDANCES OF MID-F DWARFS

    SciTech Connect (OSTI)

    Wood, Brian E.; Laming, J. Martin [Naval Research Laboratory, Space Science Division, Washington, DC 20375 (United States)

    2013-05-10T23:59:59.000Z

    A Chandra spectrum of the moderately active nearby F6 V star {pi}{sup 3} Ori is used to study the coronal properties of mid-F dwarfs. We find that {pi}{sup 3} Ori's coronal emission measure distribution is very similar to those of moderately active G and K dwarfs, with an emission measure peak near log T = 6.6 seeming to be ubiquitous for such stars. In contrast to coronal temperature, coronal abundances are known to depend on spectral type for main sequence stars. Based on this previously known relation, we expected {pi}{sup 3} Ori's corona to exhibit an extremely strong ''first ionization potential (FIP) effect'', a phenomenon first identified on the Sun where elements with low FIP are enhanced in the corona. We instead find that {pi}{sup 3} Ori's corona exhibits a FIP effect essentially identical to that of the Sun and other early G dwarfs, perhaps indicating that the increase in FIP bias toward earlier spectral types stops or at least slows for F stars. We find that {pi}{sup 3} Ori's coronal characteristics are significantly different from two previously studied mid-F stars, Procyon (F5 IV-V) and {tau} Boo (F7 V). We believe {pi}{sup 3} Ori is more representative of the coronal characteristics of mid-F dwarfs, with Procyon being different because of luminosity class, and {tau} Boo being different because of the effects of one of two close companions, one stellar ({tau} Boo B: M2 V) and one planetary.

  11. Techniques and Technology Article Aerial Surveys for Estimating Wild Turkey Abundance in

    E-Print Network [OSTI]

    Butler, Matthew J.

    Techniques and Technology Article Aerial Surveys for Estimating Wild Turkey Abundance in the Texas Aerial surveys have been used to estimate abundance of several wild bird species including wild turkeys (Meleagris gallopavo). We used inflatable turkey decoys at 3 study sites in the Texas Rolling Plains

  12. OCCUPANCY DISTRIBUTIONS ARISING IN SAMPLING FROM GIBBS-POISSON ABUNDANCE MODELS

    E-Print Network [OSTI]

    together with a sampling model. We start with a discrete model of iid stochastic species abundances, each, which is a measure of richness or diversity of species. We rederive the sam- pling formulae1 , SERVET MART´INEZ2 (iid) stochastic species abundances d = 1, ..., n , based on Gibbs

  13. X-shooter Science Verification Proposal Title: Precise abundance determination of extremely metal poor HII galaxies

    E-Print Network [OSTI]

    Liske, Jochen

    the task of obtaining a data base of HII galaxies with accurately derived abundances and a realistic poor HII galaxies Investigators Institute EMAIL ´Angeles I. D´iaz UAM angeles.diaz@uam.es Roberto and abundances derived from SDSS data can only #12;be taken as broad estimates and challenges the methodology

  14. A unified model of species immigration, extinction and abundance on islands

    E-Print Network [OSTI]

    Harmon, Luke

    ORIGINAL ARTICLE A unified model of species immigration, extinction and abundance on islands James and extinction rates as functions of species richness at dynamic equilibrium. In contrast, the approach results highlight the importance of species abundances as indi- cators of immigration and extinction rates

  15. The Solar Wind Helium Abundance: Variation with Wind Speed and the Solar Cycle

    E-Print Network [OSTI]

    Richardson, John

    The Solar Wind Helium Abundance: Variation with Wind Speed and the Solar Cycle Matthias R. Aellig Alamos National Lab., Los Alamos, NM 87545 Abstract We investigate the helium abundance in the solar wind of 1994 and early 2000 are analyzed. In agreement with similar work for previous solar cycles, we find

  16. The Texas Quail Index: Evaluating Predictors of Quail Abundance Using Citizen Science

    E-Print Network [OSTI]

    Reyna, Kelly Shane

    2009-05-15T23:59:59.000Z

    Quail Index (TQI) was a 5-year citizen-science project that evaluated several indices of quail abundance and habitat parameters as predictors of quail abundance during the ensuing fall. I found that spring cock-call counts explained 41% of the variation...

  17. Fully corrected estimates of common minke whale abundance in West Greenland in 2007

    E-Print Network [OSTI]

    Laidre, Kristin L.

    Fully corrected estimates of common minke whale abundance in West Greenland in 2007 M.P. HEIDE West Greenland in August and September 2007. A total of 8,670km of survey effort covered 11 strata SURVEY; SATELLITE TAGGING; WEST GREENLAND minke whales to fully corrected total estimates of abundance

  18. MODELING PHYTOPLANKTON ABUNDANCE IN SAGINAW BAY, LAKE HURON: USING ARTIFICIAL NEURAL NETWORKS TO DISCERN FUNCTIONAL INFLUENCE

    E-Print Network [OSTI]

    MODELING PHYTOPLANKTON ABUNDANCE IN SAGINAW BAY, LAKE HURON: USING ARTIFICIAL NEURAL NETWORKS; phytoplankton Abbreviations: ANN, artificial neural network; ClÀ , chloride; DOC, dissolved organic carbon; Kd Phytoplankton abundance, as chl a, in Saginaw Bay, Lake Huron was modeled using arti- ficial neural networks

  19. Identification in Pea Seed Mitochondria of a Late-Embryogenesis Abundant Protein Able to

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    lack of well-ordered tertiary structure of LEA proteins preventing their use as catalysts, severalIdentification in Pea Seed Mitochondria of a Late-Embryogenesis Abundant Protein Able to Protect, 38054 Grenoble cedex 9, France (D.G.) Late-embryogenesis abundant (LEA) proteins are hydrophilic

  20. The Oxygen Abundance of Nearby Galaxies from Sloan Digital Sky Survey Spectra

    E-Print Network [OSTI]

    L. S. Pilyugin; T. X. Thuan

    2007-07-19T23:59:59.000Z

    We have derived the oxygen abundance for a sample of nearby galaxies in the Data Release 5 of the Sloan Digital Sky Survey (SDSS) which possess at least two independent spectra of one or several HII regions with a detected [OIII]4363 auroral line. Since, for nearby galaxies, the [OII]3727 nebular line is out of the observed wavelength range, we propose a method to derive (O/H)_ff abundances using the classic Te method coupled with the ff relation. (O/H)_7325 abundances have also been determined, based on the [OII]7320,7330 line intensities, and using a small modification of the standard Te method. The (O/H)_ff and (O/H)_7325 abundances have been derived with both the one- and two-dimensional t_2 - t_3 relations. It was found that the (O/H)_ff abundances derived with the parametric two-dimensional t_2 - t_3 relation are most reliable. Oxygen abundances have been determined in 29 nearby galaxies, based on 84 individual abundance determinations in HII regions. Because of our selection methods, the metallicity of our galaxies lies in the narrow range 8.2 oxygen abundances in the disk of the spiral galaxy NGC 4490 is determined for the first time.

  1. Instructions for use Petrology, trace element abundances and oxygen isotopic1

    E-Print Network [OSTI]

    Tsunogai, Urumu

    Instructions for use #12;1 Petrology, trace element abundances and oxygen isotopic1 compositions@jamstec.go.jp15 16 17 #12;2 ABSTRACT1 We report the petrology, trace element abundances and oxygen isotopic and isotopic compositions as well as in their petrology.1 CAIs are composed of refractory minerals

  2. Dynamics in the Isotropic Phase of Nematogens Using 2D IR Vibrational Echo Measurements on Natural Abundance 13

    E-Print Network [OSTI]

    Fayer, Michael D.

    in an oil bath at 70 °C. Over the course of the reaction, the flask contents became significantly lighter filtration. Solvent was removed under reduced pressure to yield ~500 mg of crude brown solid. The crude (Varian Mercury 400 MHz, chloroform-d) ppm 7.66 (d, J = 8.5 Hz, 2 H) 7.59 (d, J = 8.5 Hz, 2 H) 7.50 (d, J

  3. Parental Effort and Blood Parasitism in Tengmalm's Owl: Effects of Natural and Experimental Variation in Food Abundance

    E-Print Network [OSTI]

    Shutler, Dave

    , available at http://www.jstor.org/about/terms.html. JSTOR's Terms and Conditions of Use provides, in part inip~rtanceor' \\ar\\lng cn\\~r~nmentalcon,I~tisri>;tnJ ph!>~ial ~ , ) n d ~ t i ~ ~ ~ i ,)II ~ I I > C C

  4. Dynamics in the Isotropic Phase of Nematogens Using 2D IR Vibrational Echo Measurements on Natural-Abundance 13

    E-Print Network [OSTI]

    Fayer, Michael D.

    -4-pentylbiphenyl (5CB), with the CN stretch initially used as the vibrational probe. Although the CN-thiocyanobiphenyl (5SCB) was synthesized and studied as a dilute solute in 5CB. The CN stretch of 5SCB has of fast structural dynamics in the isotropic phase of 5CB. It is shown that the 5SCB probe reports

  5. Measurement of the half-life of (198)Au in a nonmetal: High-precision measurement shows no host-material dependence

    E-Print Network [OSTI]

    Goodwin, J. R.; Nica, N.; Iacob, V. E.; Dibidad, A.; Hardy, John C.

    2010-01-01T23:59:59.000Z

    ] F. Raiola et al., Eur. Phys. J. A 19, 283 (2004). [2] B. Limata et al., Eur. Phys. J. A 28, 251 (2006). [3] T. Spillane et al., Eur. Phys. J. A 31, 203 (2007). [4] J. R. Goodwin, V. V. Golovko, V. E. Iacob, and J. C. Hardy, Eur. Phys. J. A 34... (2008); 78, 039901(E) (2008). [13] B. Wang et al., Eur. Phys. J. A 28, 375 (2006). [14] J. C. Hardy and I. S. Towner, Phys. Rev. C 79, 055502 (2009). 044320-3 ...

  6. The Abundance of Fluorine in Normal G and K Stars of the Galactic Thin Disk

    E-Print Network [OSTI]

    Pilachowski, Catherine A

    2015-01-01T23:59:59.000Z

    The abundance of fluorine is determined from the (2-0) R9 2.3358 micron feature of the molecule HF for several dozen normal G and K stars in the Galactic thin disk from spectra obtained with the Phoenix IR spectrometer on the 2.1-m telescope at Kitt Peak. The abundances are analyzed in the context of Galactic chemical evolution to explore the contributions of supernovae and asymptotic giant branch (AGB) stars to the abundance of fluorine in the thin disk. The average abundance of fluorine in the thin disk is found to be [F/Fe] = +0.23 +/- 0.03, and the [F/Fe] ratio is flat or declines slowly with metallicity in the range from -0.6 supernovae contributes significantly to the Galactic fluorine abundance, although contributions from AGB stars may also be important.

  7. Natural gas annual 1996

    SciTech Connect (OSTI)

    NONE

    1997-09-01T23:59:59.000Z

    This document provides information on the supply and disposition of natural gas to a wide audience. The 1996 data are presented in a sequence that follows natural gas from it`s production to it`s end use.

  8. Nature/Culture/Seawater

    E-Print Network [OSTI]

    Helmreich, Stefan

    This essay considers seawater as a substance and symbol in anthropological and social theory. Seawater has occupied an ambiguous place with respect to anthropological categories of nature and culture. Seawater as nature ...

  9. Supervisory Natural Gas Analyst

    Broader source: Energy.gov [DOE]

    The Department of Energys Office of Fossil Energy, Office of Oil and Natural Gas, Office of Oil and Gas Global Security and Supply (FE) is responsible for regulating natural gas imports and exports...

  10. Natural gas annual 1995

    SciTech Connect (OSTI)

    NONE

    1996-11-01T23:59:59.000Z

    The Natural Gas Annual provides information on the supply and disposition of natural gas to a wide audience including industry, consumers, Federal and State agencies, and educational institutions. The 1995 data are presented in a sequence that follows natural gas (including supplemental supplies) from its production to its end use. This is followed by tables summarizing natural gas supply and disposition from 1991 to 1995 for each Census Division and each State. Annual historical data are shown at the national level.

  11. Natural Resources Research Institute

    E-Print Network [OSTI]

    Netoff, Theoden

    /Loll ThermoWood Hybrid Poplars Peat A boost for the peat industry Value in Minnesota peat deposits Natural che

  12. Natural gas annual 1994

    SciTech Connect (OSTI)

    NONE

    1995-11-17T23:59:59.000Z

    The Natural Gas Annual provides information on the supply and disposition of natural gas to a wide audience including industry, consumers, Federal and State agencies, and educational institutions. The 1994 data are presented in a sequence that follows natural gas (including supplemental supplies) from its production to its end use. This is followed by tables summarizing natural gas supply and disposition from 1990 to 1994 for each Census Division and each State. Annual historical data are shown at the national level.

  13. NATURE CHEMISTRY | VOL 3 | OCTOBER 2011 | www.nature.com/naturechemistry 763 unlight is the most abundant source of energy we have at our

    E-Print Network [OSTI]

    Fleming, Graham R.

    . Fleming2,3 , Alexandra Olaya-Castro4 and Rienk van Grondelle5 Solar fuel production often starts will be used for solar fuel production, to direct and regulate excitation energy flow using molecular harvested from sun- light efficiently to promote photochemical reactions or to produce solar fuels, we must

  14. THE HELIUM ABUNDANCE IN POLAR CORONAL HOLES AND THE FAST SOLAR WIND

    SciTech Connect (OSTI)

    Byhring, H. S., E-mail: hanne-sigrun.byhring@uit.no [Department of Physics and Technology, University of Tromsoe, No-9037 Tromsoe (Norway)

    2011-09-10T23:59:59.000Z

    I have studied the helium abundance in polar coronal holes and the fast solar wind using a time-dependent numerical model for the hydrogen-helium solar wind that spans the mid-to-upper chromosphere, transition region, corona, and solar wind. The model calculates the particle density, flow velocity, parallel and perpendicular temperature, and heat flux for all particle species simultaneously. The focus is on (1) the coronal/solar wind helium abundance as a function of the total magnetic field expansion and (2) the coronal abundance enhancements resulting from low helium heating rates. It is shown that the magnetic field expansion factor may be important in the determination of the solar wind helium abundance and that this can be understood in terms of gravitational settling in the chromosphere. I find that a total magnetic field expansion factor of about 20 is consistent with the observed helium abundance in the solar wind. Furthermore, it is demonstrated that existing observations, both spectroscopic observations of the corona and in situ observations in the solar wind, are compatible with helium abundance enhancements in the corona. For proton-electron plasma properties in accordance with observations, the coronal helium abundance enhancements occur in the region 1.2-2 R{sub sun}.

  15. On the maximum value of the cosmic abundance of oxygen and the oxygen yield

    E-Print Network [OSTI]

    L. S. Pilyugin; T. X. Thuan; J. M. Vilchez

    2007-01-11T23:59:59.000Z

    We search for the maximum oxygen abundance in spiral galaxies. Because this maximum value is expected to occur in the centers of the most luminous galaxies, we have constructed the luminosity - central metallicity diagram for spiral galaxies, based on a large compilation of existing data on oxygen abundances of HII regions in spiral galaxies. We found that this diagram shows a plateau at high luminosities (-22.3 oxygen abundance 12+log(O/H) ~ 8.87. This provides strong evidence that the oxygen abundance in the centers of the most luminous metal-rich galaxies reaches the maximum attainable value of oxygen abundance. Since some fraction of the oxygen (about 0.08 dex) is expected to be locked into dust grains, the maximum value of the true gas+dust oxygen abundance in spiral galaxies is 12+log(O/H) ~ 8.95. This value is a factor of ~ 2 higher than the recently estimated solar value. Based on the derived maximum oxygen abundance in galaxies, we found the oxygen yield to be about 0.0035, depending on the fraction of oxygen incorporated into dust grains.

  16. Stochastic chemical enrichment in metal-poor systems II. Abundance ratios and scatter

    E-Print Network [OSTI]

    T. Karlsson; B. Gustafsson

    2005-04-27T23:59:59.000Z

    A stochastic model of the chemical enrichment of metal-poor systems by core-collapse supernovae is used to study the scatter in stellar abundance ratios. The resulting scatter in abundance ratios, e.g. as functions of the overall metallicity, is demonstrated to be crucially dependent on the as yet uncertain supernovae yields. The observed abundance ratios and their scatters therefore have diagnostic power as regards the yields. The relatively small star-to-star scatter observed in many chemical abundance ratios, e.g. by Cayrel et al. (2004) for stars down to [Fe/H] = -4, is tentatively explained by the averaging of a large number of contributing supernovae and by the cosmic selection effects favoring contributions from supernovae in a certain mass range for the most metal-poor stars. The scatter in observed abundances of alpha-elements is understood in terms of observational errors only, while additional spread in yields or sites of nucleosynthesis may affect the odd-even elements Na and Al. For the iron-group elements we find systematically too high predicted Cr/Fe and Cr/Mg ratios, as well as differences between the different sets of yields, both in terms of predicted abundance ratios and scatter. The semi-empirical yields recently suggested by Francois et al. (2004) are found to lead to scatter in abundance ratios significantly greater than observed, when applied in the inhomogeneous models. "Spurs", very narrow sequences in abundance-ratio diagrams, may disclose a single-supernova origin of the elements of the stars on the sequence. Verification of the existence of such features, called single supernova sequences (SSSs), is challenging. This will require samples of several hundred stars with abundance ratios observed to accuracies of 0.05 dex or better.

  17. 2005 Nature Publishing Group Mammal-like muscles power swimming in a

    E-Print Network [OSTI]

    DeWitt, Thomas J.

    dorsal fin, where the RM is most abundant, showed that all sharks had a core temperature about 18­20 8C© 2005 Nature Publishing Group Mammal-like muscles power swimming in a cold-water shark Diego, within the fishes the tunas and lamnid sharks deviate from the ectothermic strategy, maintaining elevated

  18. The Role of Concrete Marine Structures in the Recovery of Energy and Natural Resources from the

    E-Print Network [OSTI]

    Frandsen, Jannette B.

    The Role of Concrete Marine Structures in the Recovery of Energy and Natural Resources from Concrete materials are derived from some of the most abundant and economically available sources on this planet. Recent advancements in the development of concrete technology related to the durability, strength

  19. Non-LTE metal abundances in V652 Her and HD144941

    E-Print Network [OSTI]

    N. Przybilla; M. F. Nieva; U. Heber; C. S. Jeffery

    2005-12-06T23:59:59.000Z

    Two evolutionary scenarios are proposed for the formation of extreme helium stars: a post-AGB star suffering from a late thermal pulse, or the merger of two white dwarfs. An identification of the evolutionary channel for individual objects has to rely on surface abundances. We present preliminary results from a non-LTE analysis of CNO, Mg and S for two unique objects, V652 Her and HD144941. Non-LTE abundance corrections for these elements range from negligible values to ~0.7 dex. Non-LTE effects typically lead to systematic shifts in the abundances relative to LTE and reduce the uncertainties.

  20. EIA - Natural Gas Pipeline Network - Largest Natural Gas Pipeline...

    U.S. Energy Information Administration (EIA) Indexed Site

    Interstate Pipelines Table About U.S. Natural Gas Pipelines - Transporting Natural Gas based on data through 20072008 with selected updates Thirty Largest U.S. Interstate Natural...

  1. Environmental Survey Report for ORNL: Small Mammal Abundance and Distribution Survey Oak Ridge National Environmental Research Park 2009 - 2010

    SciTech Connect (OSTI)

    Giffen, Neil R [ORNL; Reasor, R. Scott [Oak Ridge Institute for Science and Education (ORISE); Campbell, Claire L. [Oak Ridge Institute for Science and Education (ORISE)

    2009-12-01T23:59:59.000Z

    This report summarizes a 1-year small mammal biodiversity survey conducted on the Oak Ridge National Environmental Research Park (OR Research Park). The task was implemented through the Oak Ridge National Laboratory (ORNL) Natural Resources Management Program and included researchers from the ORNL Environmental Sciences Division, interns in the Oak Ridge Institute for Science and Education Higher Education Research Experiences Program, and ORNL Environmental Protection Services staff. Eight sites were surveyed reservation wide. The survey was conducted in an effort to determine species abundance and diversity of small mammal populations throughout the reservation and to continue the historical inventory of small mammal presence for biodiversity records. This data collection effort was in support of the approved Wildlife Management Plan for the Oak Ridge Reservation, a major goal of which is to maintain and enhance wildlife biodiversity on the Reservation. Three of the sites (Poplar Creek, McNew Hollow, and Deer Check Station Field) were previously surveyed during a major natural resources inventory conducted in 1996. Five new sites were included in this study: Bearden Creek, Rainy Knob (Natural Area 21), Gum Hollow, White Oak Creek and Melton Branch. The 2009-2010 small mammal surveys were conducted from June 2009 to July 2010 on the Oak Ridge National Environmental Research Park (OR Research Park). The survey had two main goals: (1) to determine species abundance and diversity and (2) to update historical records on the OR Research Park. The park is located on the Department of Energy-owned Oak Ridge Reservation, which encompasses 13,580 ha. The primary focus of the study was riparian zones. In addition to small mammal sampling, vegetation and coarse woody debris samples were taken at certain sites to determine any correlations between habitat and species presence. During the survey all specimens were captured and released using live trapping techniques including Sherman and pitfall traps. In total 227 small mammals representing nine species were captured during the course of the study. The most common species found in the study was the white-footed mouse (Peromyscus leucopus). The least common species found were the deer mouse (Peromyscus maniculatus), meadow jumping mouse (Zapus hudsonius), woodland vole (Microtus pinetorum), and northern short-tailed shrew (Blarina brevicauda).

  2. The melting and abundance of open charm hadrons

    E-Print Network [OSTI]

    A. Bazavov; H. -T. Ding; P. Hegde; O. Kaczmarek; F. Karsch; E. Laermann; Y. Maezawa; Swagato Mukherjee; H. Ohno; P. Petreczky; C. Schmidt; S. Sharma; W. Soeldner; M. Wagner

    2014-09-01T23:59:59.000Z

    Ratios of cumulants of conserved net charge fluctuations are sensitive to the degrees of freedom that are carriers of the corresponding quantum numbers in different phases of strong interaction matter. Using lattice QCD with 2+1 dynamical flavors and quenched charm quarks we calculate second and fourth order cumulants of net charm fluctuations and their correlations with other conserved charges such as net baryon number, electric charge and strangeness. Analyzing appropriate ratios of these cumulants we probe the nature of charmed degrees of freedom in the vicinity of the QCD chiral crossover region. We show that for temperatures above the chiral crossover transition temperature, charmed degrees of freedom can no longer be described by an uncorrelated gas of hadrons. This suggests that the dissociation of open charm hadrons and the emergence of deconfined charm states sets in just near the chiral crossover transition. Till the crossover region we compare these lattice QCD results with two hadron resonance gas models --including only the experimentally established charmed resonances and also including additional states predicted by quark model and lattice QCD calculations. This comparison provides evidence for so far unobserved charmed hadrons that contribute to the thermodynamics in the crossover region.

  3. Oxygen abundances in dwarf irregular galaxies and the metallicity - luminosity relationship

    E-Print Network [OSTI]

    L. S. Pilyugin

    2001-05-21T23:59:59.000Z

    The low-luminosity dwarf irregular galaxies are considered. The oxygen abundances in HII regions of dwarf irregular galaxies were recalculated from published spectra through the recently suggested P - method. It has been found that the metallicity of low-luminosity dwarf irregular galaxies, with a few exceptions, correlates well with galaxy luminosity. The dispersion of oxygen abundances around the metallicity - luminosity relationship increases with decreasing of galaxy luminosity, as was found by Richer and McCall (1995). No relationship between the oxygen abundance and the absolute magnitude in the blue band for irregular galaxies obtained by Hidalgo-Gamez and Olofsson (1998) can be explained by the large uncertainties in the oxygen abundances derived through the Te - method, that in turn can be explained by the large uncertainties in the measurements of the strengths of the weak oxygen line [OIII]4363 used in the Te - method.

  4. acid-base transporter abundance: Topics by E-print Network

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

    Page Last Page Topic Index 1 Transport Phenomena and Light Element Abundances in the Sun and Solar Type Stars Astrophysics (arXiv) Summary: The observations of light elements...

  5. Spatial pattern and temporal dynamics of northern bobwhite abundance and agricultural landuse, and potential casual factors 

    E-Print Network [OSTI]

    Okay, Atiye Zeynep

    2006-04-12T23:59:59.000Z

    There was a long-term decline in northern bobwhite (Colinus virginianus, NBW) abundance since the 1920s, based on the Christmas Bird Count (CBC) data, but with substantial spatial and temporal variations across its range. ...

  6. Monte Carlo Method for Calculating Oxygen Abundances and Their Uncertainties from Strong-Line Flux Measurements

    E-Print Network [OSTI]

    Bianco, Federica B; Oh, Seung Man; Fierroz, David; Liu, Yuqian; Kewley, Lisa; Graur, Or

    2015-01-01T23:59:59.000Z

    We present the open-source Python code pyMCZ that determines oxygen abundance and its distribution from strong emission lines in the standard metallicity scales, based on the original IDL code of Kewley & Dopita (2002) with updates from Kewley & Ellison (2008), and expanded to include more recently developed scales. The standard strong-line diagnostics have been used to estimate the oxygen abundance in the interstellar medium through various emission line ratios in many areas of astrophysics, including galaxy evolution and supernova host galaxy studies. We introduce a Python implementation of these methods that, through Monte Carlo (MC) sampling, better characterizes the statistical reddening-corrected oxygen abundance confidence region. Given line flux measurements and their uncertainties, our code produces synthetic distributions for the oxygen abundance in up to 13 metallicity scales simultaneously, as well as for E(B-V), and estimates their median values and their 66% confidence regions. In additi...

  7. Influences of vegetation characteristics and invertebrate abundance of Rio Grande wild turkey populations, Edwards Plateau, Texas

    E-Print Network [OSTI]

    Randel, Charles Jack

    2005-02-17T23:59:59.000Z

    Since 1970, Rio Grande wild turkey (Meleagris gallapavo intermedia) numbers in the southern region of the Edwards Plateau of Texas have been declining. Nest-site characteristics and invertebrate abundance were hypothesized as limiting wild turkey...

  8. Environmental factors affecting planktonic foraminifera abundance and distribution in the Northeast Gulf of Mexico

    E-Print Network [OSTI]

    Ravula, Sharath Reddy

    2005-08-29T23:59:59.000Z

    shift in the species abundances and depths occurred between eddies. Species occurred where physical factors were compatible with conditions and feeding opportunities they were adapted to. Three species pink and white Globigerinoides ruber...

  9. Abundance analysis of SB2 binary stars with HgMn primaries

    E-Print Network [OSTI]

    T. Ryabchikova

    1998-05-06T23:59:59.000Z

    We present a short review of the abundances in the atmospheres of SB2 systems with Mercury-Manganese (HgMn) primaries. Up to now a careful study has been made for both components of 8 out of 17 known SB2 binaries with orbital periods shorter than 100 days and mass ratio ranging from 1.08 to 2.2. For all eight systems we observe a lower Mn abundance in the secondary's atmospheres than in the primary's. Significant difference in the abundances is also found for some peculiar elements such as Ga, Xe, Pt. All secondary stars with effective temperatures less than 10000 K show abundance characteristics typical of the metallic-line stars.

  10. Reef Habitats in the Middle Atlantic Bight: Abundance, Distribution, Associated Biological

    E-Print Network [OSTI]

    abundance of fishery resources are in- and Biggs, 1988; Poppe et al., 1994). fluenced by physical and other can Stumf and Biggs, 1988; Poppe et al., lead to a better understanding of how 1994; NOAA National

  11. Earth abundant materials for high efficiency heterojunction thin film solar cells

    E-Print Network [OSTI]

    Buonassisi, Tonio

    We investigate earth abundant materials for thin-film solar cells that can meet tens of terawatts level deployment potential. Candidate materials are identified by combinatorial search, large-scale electronic structure ...

  12. EIA - Natural Gas Pipeline Network - Natural Gas Supply Basins...

    U.S. Energy Information Administration (EIA) Indexed Site

    Corridors About U.S. Natural Gas Pipelines - Transporting Natural Gas based on data through 20072008 with selected updates U.S. Natural Gas Supply Basins Relative to Major Natural...

  13. Coronal and Solar Wind Elemental Abundances J. C. Raymond , J. E. Mazur + , F. Allegrini , E. Antonucci # , G. Del Zanna ,

    E-Print Network [OSTI]

    Del Zanna, Giulio

    Coronal and Solar Wind Elemental Abundances J. C. Raymond #3; , J. E. Mazur + , F. Allegrini #3, Johns Hopkins Road, Laurel, MD 20723 USA k Naval Research Laboratory, Washington, DC USA ++ MIT, Room 37. Coronal elemental abundances, as compared with abundances in the solar wind and solar energetic particles

  14. Petrologic mapping of the Moon using Fe, Mg, and Al abundances A.A. Berezhnoy a,*, N. Hasebe a

    E-Print Network [OSTI]

    Berezhnoi, Aleksei A.

    Petrologic mapping of the Moon using Fe, Mg, and Al abundances A.A. Berezhnoy a,*, N. Hasebe a , M for the presence of polar lunar hydrogen. Using Mg, Fe, and Al abundances, petrologic maps containing information: Moon; Maps of elemental abundances; Petrology; End-member rocks; Chemistry of lunar polar regions; Rock

  15. The N/O abundance ratio in the lowest-metallicity blue compact dwarf galaxies

    E-Print Network [OSTI]

    Y. Izotov; F. Chaffee; C. Foltz; K. Fricke; R. Green; N. Guseva; K. Noeske; P. Papaderos; T. Thuan

    2001-09-27T23:59:59.000Z

    The results of the N/O abundance determination in a sample of low-metallicity blue compact dwarf (BCD) galaxies based on new spectroscopic observations with large telescopes (Keck, VLT, MMT, 4m KPNO) are presented. We show that the N/O abundance ratio is constant at lowest metallicities < Zsun/20, confirming previous findings and strongly supporting the origin of nitrogen as a primary element.

  16. A New Technique for Determining Europium Abundances in Solar-Metallicity Stars

    E-Print Network [OSTI]

    Peek, Kathryn M G

    2009-01-01T23:59:59.000Z

    We present a new technique for measuring the abundance of europium, a representative r-process element, in solar-metallicity stars. Our algorithm compares LTE synthetic spectra with high-resolution observational spectra using a chi-square-minimization routine. The analysis is fully automated, and therefore allows consistent measurement of blended lines even across very large stellar samples. We compare our results with literature europium abundance measurements and find them to be consistent; we also find our method generates smaller errors.

  17. Chemical Abundances in AGN Environment: X-Ray/UV Campaign on the MRK 279 Outflow

    E-Print Network [OSTI]

    Nahum Arav; Jack R. Gabel; Kirk T. Korista; Jelle S. Kaastra; Gerard A. Kriss; Ehud Behar; Elisa Costantini; C. Martin Gaskell; Ari Laor; Nalaka Kodituwakku; Daniel Proga; Masao Sako; Jennifer E. Scott; Katrien C. Steenbrugge

    2006-11-29T23:59:59.000Z

    We present the first reliable determination of chemical abundances in an AGN outflow. The abundances are extracted from the deep and simultaneous FUSE and HST/STIS observations of Mrk 279. This data set is exceptional for its high signal-to-noise, unblended doublet troughs and little Galactic absorption contamination. These attributes allow us to solve for the velocity-dependent covering fraction, and therefore obtain reliable column densities for many ionic species. For the first time we have enough such column densities to simultaneously determine the ionization equilibrium and abundances in the flow. Our analysis uses the full spectral information embedded in these high-resolution data. Slicing a given trough into many independent outflow elements yields the extra constraints needed for a physically meaningful abundances determination. We find that relative to solar the abundances in the Mrk 279 outflow are (linear scaling): carbon 2.2+/-0.7, nitrogen 3.5+/-1.1 and oxygen 1.6+/-0.8. Our UV-based photoionization and abundances results are in good agreement with the independent analysis of the simultaneous Mrk 279 X-ray spectra. This is the best agreement between the UV and X-ray analyses of the same outflow to date.

  18. Abundances, Stellar Parameters, and Spectra From the SDSS-III/APOGEE Survey

    E-Print Network [OSTI]

    Holtzman, Jon A; Johnson, Jennifer A; Prieto, Carlos Allende; Anders, Friedrich; Andrews, Brett; Beers, Timothy C; Bizyaev, Dmitry; Blanton, Michael R; Bovy, Jo; Carrera, Ricardo; Cunha, Katia; Eisenstein, Daniel J; Feuillet, Diane; Frinchaboy, Peter M; Galbraith-Frew, Jessica; Perez, Ana E Garcia; Hernandez, D Anibal Garcia; Hasselquist, Sten; Hayden, Michael R; Hearty, Fred R; Ivans, Inese; Majewski, Steven R; Martell, Sarah; Meszaros, Szabolcs; Muna, Demitri; Nidever, David L; Nguyen, Duy Cuong; O'Connell, Robert W; Pan, Kaike; Pinsonneault, Marc; Robin, Annie C; Schiavon, Ricardo P; Shane, Neville; Sobeck, Jennifer; Smith, Verne V; Troup, Nicholas; Weinberg, David H; Wilson, John C; Wood-Vasey, W M; Zamora, Olga; Zasowski, Gail

    2015-01-01T23:59:59.000Z

    The SDSS-III/APOGEE survey operated from 2011-2014 using the APOGEE spectrograph, which collects high-resolution (R~22,500), near-IR (1.51-1.70 microns) spectra with a multiplexing (300 fiber-fed objects) capability. We describe the survey data products that are publicly available, which include catalogs with radial velocity, stellar parameters, and 15 elemental abundances for over 150,000 stars, as well as the more than 500,000 spectra from which these quantities are derived. Calibration relations for the stellar parameters (Teff, log g, [M/H], [alpha/M]) and abundances (C, N, O, Na, Mg, Al, Si, S, K, Ca, Ti, V, Mn, Fe, Ni) are presented and discussed. The internal scatter of the abundances within clusters indicates that abundance precision is generally between 0.05 and 0.09 dex across a broad temperature range; within more limited ranges and at high S/N, it is smaller for some elemental abundances. We assess the accuracy of the abundances using comparison of mean cluster metallicities with literature values...

  19. Warner College of Natural Resources Warner College of Natural

    E-Print Network [OSTI]

    Collett Jr., Jeffrey L.

    , and scientific investigation of renewable and nonrenewable natural resources. Programs include the study of everyWarner College of Natural Resources Warner College of Natural Resources Office in Natural Resources, and Conservation Biology Forestry Geology Natural Resource Recreation and Tourism Natural Resources Management

  20. Natural gas annual 1997

    SciTech Connect (OSTI)

    NONE

    1998-10-01T23:59:59.000Z

    The Natural Gas Annual provides information on the supply and disposition of natural gas to a wide audience including industry, consumers, Federal and State agencies, and educational institutions. The 1997 data are presented in a sequence that follows natural gas (including supplemental supplies) from its production to its end use. This is followed by tables summarizing natural gas supply and disposition from 1993 to 1997 for each Census Division and each State. Annual historical data are shown at the national level. 27 figs., 109 tabs.

  1. Liquefied Natural Gas (Iowa)

    Broader source: Energy.gov [DOE]

    This document adopts the standards promulgated by the National Fire Protection Association as rules for the transportation, storage, handling, and use of liquefied natural gas. The NFPA standards...

  2. Natural Heritage Program (Missouri)

    Broader source: Energy.gov [DOE]

    Natural Heritage Reviews are conducted by the Missouri Department of Conservation on request in order to assess proposed project sites and adjacent lands. Reviews determine whether potential...

  3. Natural gas dehydration apparatus

    DOE Patents [OSTI]

    Wijmans, Johannes G; Ng, Alvin; Mairal, Anurag P

    2006-11-07T23:59:59.000Z

    A process and corresponding apparatus for dehydrating gas, especially natural gas. The process includes an absorption step and a membrane pervaporation step to regenerate the liquid sorbent.

  4. Mechanical property evaluation of natural fiber coir composite

    SciTech Connect (OSTI)

    Harish, S. [Department of Mechanical and Aerospace Engineering, Arizona State University (United States); Michael, D. Peter [Department of Mechanical Engineering, College of Engineering, Guindy (India); Bensely, A. [Department of Mechanical Engineering, College of Engineering, Guindy (India)], E-mail: benzlee5@yahoo.com; Lal, D. Mohan [Department of Mechanical Engineering, College of Engineering, Guindy (India); Rajadurai, A. [Department of Production Engineering, Madras Institute of Technology (India)

    2009-01-15T23:59:59.000Z

    The fiber which serves as a reinforcement in reinforced plastics may be synthetic or natural. Past studies show that only artificial fibers such as glass, carbon etc., have been used in fiber-reinforced plastics. Although glass and other synthetic fiber-reinforced plastics possess high specific strength, their fields of application are very limited because of their inherent higher cost of production. In this connection, an investigation has been carried out to make use of coir, a natural fiber abundantly available in India. Natural fibers are not only strong and lightweight but also relatively very cheap. In the present work, coir composites are developed and their mechanical properties are evaluated. Scanning electron micrographs obtained from fractured surfaces were used for a qualitative evaluation of the interfacial properties of coir/epoxy and compared with glass fiber/epoxy. These results indicate that coir can be used as a potential reinforcing material for making low load bearing thermoplastic composites.

  5. The abundance of presolar grains in comet 81P/WILD 2

    SciTech Connect (OSTI)

    Floss, Christine; Stadermann, Frank J.; Ong, W. J. [Laboratory for Space Sciences, Physics Department, Washington University, 1 Brookings Drive, St. Louis, MO 63130 (United States)] [Laboratory for Space Sciences, Physics Department, Washington University, 1 Brookings Drive, St. Louis, MO 63130 (United States); Kearsley, Anton T. [Impacts and Astromaterials Research Centre, Science Facilities, Natural History Museum, London SW7 5BD (United Kingdom)] [Impacts and Astromaterials Research Centre, Science Facilities, Natural History Museum, London SW7 5BD (United Kingdom); Burchell, Mark J., E-mail: floss@wustl.edu [Centre for Astrophysics and Planetary Sciences, School of Physical Sciences, University of Kent, Canterbury, Kent CT2 7NH (United Kingdom)

    2013-02-15T23:59:59.000Z

    We carried out hypervelocity impact experiments in order to test the possibility that presolar grains are preferentially destroyed during impact of the comet 81P/Wild 2 samples into the Stardust Al foil collectors. Powdered samples of the ungrouped carbonaceous chondrite Acfer 094 were shot at 6 km s{sup -1} into Stardust flight spare Al foil. Craters from the Acfer 094 test shots, as well as ones from the actual Stardust cometary foils, were analyzed by NanoSIMS ion imaging to search for presolar grains. We found two O-rich presolar grains and two presolar SiC grains in the Acfer 94 test shots, with measured abundances in the foils of 4 and 5 ppm, respectively, significantly lower than the amount of presolar grains actually present in this meteorite. Based on known abundances of these phases in Acfer 094, we estimate a loss of over 90% of the O-rich presolar grains; the fraction of SiC lost is lower, reflecting its higher resistance to destruction. In the Stardust cometary foils, we identified four O-rich presolar grains in 5000 {mu}m{sup 2} of crater residue. Including a presolar silicate grain found by Leitner et al., the overall measured abundance of O-rich presolar grains in Wild 2 is {approx}35 ppm. No presolar SiC has been found in the foil searches, although one was identified in the aerogel samples. Based on the known abundances of presolar silicates and oxides in Acfer 094, we can calculate the pre-impact abundances of these grains in the Stardust samples. Our calculations indicate initial abundances of 600-830 ppm for O-rich presolar grains. Assuming a typical diameter of {approx}300 nm for SiC suggests a presolar SiC abundance of {approx}45 ppm. Analyses of the Stardust samples indicated early on that recognizable presolar components were not particularly abundant, an observation that was contrary to expectations that the cometary material would, like interplanetary dust particles, be dominated by primitive materials from the early solar system (including abundant presolar grains), which had remained essentially unaltered over solar system history in the cold environment of the Kuiper Belt. Our work shows that comet Wild 2, in fact, does contain more presolar grains than measurements on the Stardust samples suggest, with abundances similar to those observed in primitive IDPs.

  6. New Rare Earth Element Abundance Distributions for the Sun and Five r-Process-Rich Very Metal-Poor Stars

    E-Print Network [OSTI]

    Sneden, Christopher; Cowan, John J; Ivans, Inese I; Hartog, Elizabeth A Den

    2009-01-01T23:59:59.000Z

    We have derived new abundances of the rare-earth elements Pr, Dy, Tm, Yb, and Lu for the solar photosphere and for five very metal-poor, neutron-capture r-process-rich giant stars. The photospheric values for all five elements are in good agreement with meteoritic abundances. For the low metallicity sample, these abundances have been combined with new Ce abundances from a companion paper, and reconsideration of a few other elements in individual stars, to produce internally-consistent Ba, rare-earth, and Hf (56<= Z <= 72) element distributions. These have been used in a critical comparison between stellar and solar r-process abundance mixes.

  7. Natural Intrinsic Geometrical Symmetries

    E-Print Network [OSTI]

    Haesen, Stefan; 10.3842/SIGMA.2009.086

    2009-01-01T23:59:59.000Z

    A proposal is made for what could well be the most natural symmetrical Riemannian spaces which are homogeneous but not isotropic, i.e. of what could well be the most natural class of symmetrical spaces beyond the spaces of constant Riemannian curvature, that is, beyond the spaces which are homogeneous and isotropic, or, still, the spaces which satisfy the axiom of free mobility.

  8. Abundance and ecological implications of microplastic debris in the North Pacific Subtropical Gyre

    E-Print Network [OSTI]

    Goldstein, Miriam Chanita

    2012-01-01T23:59:59.000Z

    of the central North Pacific ocean. Nature 241:271–271. doi:waste distributions in Pacific Ocean. Nature 247:30–32. doi:of the central North Pacific ocean. Nature 241:271–271. doi:

  9. Natural SUSY and the Higgs boson

    SciTech Connect (OSTI)

    Huang, Peisi [Dept. of Physics, University of Wisconsin-Madison, Madison, WI 53706 (United States)

    2014-01-01T23:59:59.000Z

    Supersymmetry (SUSY) solves the hierarchy problem by introducing a super partner to each Standard Model(SM) particle. SUSY must be broken in nature, which means the fine-tuning is reintroduced to some level. Natural SUSY models enjoy low fine-tuning by featuring a small super potential parameter ? ~ 125 GeV, while the third generation squarks have mass less than 1.5 TeV. First and second generation sfermions can be at the multi-TeV level which yields a decoupling solution to the SUSY flavor and CP problem. However, models of Natural SUSY have difficulties in predicting a m{sub h} at 125 GeV, because the third generation is too light to give large radiative correction to the Higgs mass. The models of Radiative Natural SUSY (RNS) address this problem by allowing for high scale soft SUSY breaking Higgs mass m{sub Hu} > m{sub 0}, which leads to automatic cancellation by the Renormalization Group (RG) running effect. Coupled with the large mixing in the stop sector, RNS allows low fine-tuning at 3-10 % level and a 125 GeV SM-like Higgs. RNS can be reached at the LHC, and a linear collider. If the strong CP problem is solved by the Peccei-Quinn mechanism, then RNS accommodates mixed axion-Higgsino cold dark matter, where the Higgsino-like WIMPs, which in this case make up only a fraction of the relic abundance, can be detectable at future WIMP detectors.

  10. Oxygen abundances in G- and F-type stars from HARPS

    E-Print Network [OSTI]

    de Lis, S Bertran; Adibekyan, V Zh; Santos, N C; Sousa, S G

    2015-01-01T23:59:59.000Z

    We present a detailed and uniform study of oxygen abundance from two different oxygen lines at 6158$\\AA$ and 6300$\\AA$ in a large sample of solar-type stars. The results are used to check the behaviour of these spectral lines as oxygen abundance indicators and to study the evolution of oxygen in thick and thin disk populations of the Galaxy. Equivalent width measurements were carried out for the [OI]~6158$\\AA$ and OI~6300$\\AA$ lines. LTE abundances were obtained from these two lines in 610 and 535 stars, respectively. We were able to measure oxygen abundance from both indicators in 447 stars, enabling us, for the first time, to compare them in a uniform way. Careful error analysis has been performed. We found that oxygen abundances derived from the 6158$\\AA$ and 6300$\\AA$ lines agree to within 0.1dex in 58\\% of the stars in our sample, and this result improves for higher signal-to-noise values. We confirm an oxygen enhancement in stars of the thick disk, as has also been seen for other $\\alpha$-elements. The ...

  11. The Gaia-ESO Survey: Detailed Abundances in the Metal-poor Globular Cluster NGC 4372

    E-Print Network [OSTI]

    Roman, I San; Geisler, D; Villanova, S; Kacharov, N; Koch, A; Carraro, G; Tautvaišiene, G; Vallenari, A; Alfaro, E J; Bensby, T; Flaccomio, E; Francois, P; Korn, A J; Pancino, E; Recio-Blanco, A; Smiljanic, R; Bergemann, M; Costado, M T; Damiani, F; Heiter, U; Hourihane, A; Jofré, P; Lardo, C; de Laverny, P; Masseron, T; Morbidelli, L; Sbordone, L; Sousa, S G; Worley, C C; Zaggia, S

    2015-01-01T23:59:59.000Z

    We present the abundance analysis for a sample of 7 red giant branch stars in the metal-poor globular cluster NGC 4372 based on UVES spectra acquired as part of the Gaia-ESO Survey. This is the first extensive study of this cluster from high resolution spectroscopy. We derive abundances of O, Na, Mg, Al, Si, Ca, Sc, Ti, Fe, Cr, Ni, Y, Ba, and La. We find a metallicity of [Fe/H] = -2.19 $\\pm$ 0.03 and find no evidence for a metallicity spread. This metallicity makes NGC 4372 one of the most metal-poor galactic globular clusters. We also find an {\\alpha}-enhancement typical of halo globular clusters at this metallicity. Significant spreads are observed in the abundances of light elements. In particular we find a Na-O anti-correlation. Abundances of O are relatively high compared with other globular clusters. This could indicate that NGC 4372 was formed in an environment with high O for its metallicity. A Mg-Al spread is also present which spans a range of more than 0.5 dex in Al abundances. Na is correlated wit...

  12. NEON AND CNO ABUNDANCES FOR EXTREME HELIUM STARS-A NON-LTE ANALYSIS

    SciTech Connect (OSTI)

    Pandey, Gajendra [Indian Institute of Astrophysics, Bangalore, 560034 (India); Lambert, David L., E-mail: pandey@iiap.res.in, E-mail: dll@astro.as.utexas.edu [W.J. McDonald Observatory, University of Texas at Austin, Austin, TX 78712-1083 (United States)

    2011-02-01T23:59:59.000Z

    A non-LTE (NLTE) abundance analysis was carried out for three extreme helium stars (EHes): BD+10{sup 0} 2179, BD-9{sup 0} 4395, and LS IV+6{sup 0} 002, from their optical spectra with NLTE model atmospheres. NLTE TLUSTY model atmospheres were computed with H, He, C, N, O, and Ne treated in NLTE. Model atmosphere parameters were chosen from consideration of fits to observed He I line profiles and ionization equilibria of C and N ions. The program SYNSPEC was then used to determine the NLTE abundances for Ne as well as H, He, C, N, and O. LTE neon abundances from Ne I lines in the EHes: LSE 78, V1920 Cyg, HD 124448, and PV Tel, are derived from published models and an estimate of the NLTE correction applied to obtain the NLTE Ne abundance. We show that the derived abundances of these key elements, including Ne, are well matched with semi-quantitative predictions for the EHe resulting from a cold merger (i.e., no nucleosynthesis during the merger) of an He white dwarf with a C-O white dwarf.

  13. Clues on the evolution of abundance gradients and on AGB nucleosynthesis

    E-Print Network [OSTI]

    Stasinska, G; Bresolin, F; Tsamis, Yi

    2013-01-01T23:59:59.000Z

    We have obtained deep spectra of 26 planetary nebulae (PNe) and 9 compact HII regions in the nearby spiral galaxy NGC 300, and analyzed them together with those of the giant HII regions previously observed. We have determined the physical properties of all these objects and their He, N, O, Ne, S and Ar abundances in a consistent way. We find that, globally, compact HII regions have abundance ratios similar to those of giant HII regions, while PNe have systematically larger N/O ratios and similar Ne/O and Ar/O ratios. We demonstrate that the nitrogen enhancement in PNe cannot be only due to second dredge-up in the progenitor stars, since their initial masses are around 2--2.5\\,\\msun. An extra mixing process is required, perhaps driven by stellar rotation. Concerning the radial abundance distribution, PNe behave differently from HII regions: in the central part of the galaxy their average O/H abundance ratio is 0.15 dex smaller. Their abundance dispersion at any galactocentric radius is significantly larger tha...

  14. 47 Natural Gas Market Trends NATURAL GAS MARKET TRENDS

    E-Print Network [OSTI]

    47 Natural Gas Market Trends Chapter 5 NATURAL GAS MARKET TRENDS INTRODUCTION Natural gas discusses current natural gas market conditions in California and the rest of North America, followed on the outlook for demand, supply, and price of natural gas for the forecasted 20-year horizon. It also addresses

  15. Tenneco upgrades natural gasoline

    SciTech Connect (OSTI)

    O'Gorman, E.K.

    1986-08-01T23:59:59.000Z

    Tenneco Oil Co. recently completed a natural gasoline upgrading project at its LaPorte, Tex., facility. The project was started in October 1985. The purpose was to fractionate natural gasoline and isomerize the n-pentane component. Three factors made this a particularly attractive project for the LaPorte complex: 1. The phase down of lead in gasoline made further processing of natural gasoline desirable. 2. Idle equipment and trained personnel were available at the plant as a result of a switch of Tenneco's natural gas liquids (NGL) fractionation to its Mont Belvieu, Tex., facility. 3. The plant interconnects with Houston's local markets. It has pipelines to Mont Belvieu, Texas City, and plants along the Houston Ship Channel, as well as truck, tank car, and barge-loading facilities. Here are the details on the operation of the facilities, the changes which were required to enable the plant to operate successfully, and how this conversion was completed in a timely fashion.

  16. Natural gas monthly

    SciTech Connect (OSTI)

    NONE

    1996-05-01T23:59:59.000Z

    This document highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Data presented include volume and price, production, consumption, underground storage, and interstate pipeline activities.

  17. NATURAL MARINE HYDROCARBON SEEPAGE

    E-Print Network [OSTI]

    Luyendyk, Bruce

    affects ocean chemistry (Dando and Hovland, 1992) and provides a natural source of petroleum pollution the water column above submarine vents, plumes of hydrocarbon gas bubbles act as acoustic scattering targets

  18. Natural Resource Specialist

    Broader source: Energy.gov [DOE]

    A successful candidate in this position will serve as a Natural Resource Specialist responsible for participating in the development and implementation of short-term and long-term regional (multi...

  19. Natural Gas Regulations (Kentucky)

    Broader source: Energy.gov [DOE]

    Kentucky Administrative Regulation title 805 promulgates the rules and regulations pertaining to natural gas production in Kentucky. In addition to KAR title 405, chapter 30, which pertains to any...

  20. Future of Natural Gas

    Office of Environmental Management (EM)

    of Natural Gas Bill Eisele, CEM SC Electric & Gas Co Hosted by: FEDERAL UTILITY PARTNERSHIP WORKING GROUP SEMINAR November 5-6, 2014 Cape Canaveral. Florida Agenda * Gas Facts *...

  1. Thorium Abundances in Solar Twins and Analogues: Implications for the Habitability of Extrasolar Planetary Systems

    E-Print Network [OSTI]

    Unterborn, Cayman T; Panero, Wendy R

    2015-01-01T23:59:59.000Z

    We present the first investigation of Th abundances in Solar twins and analogues to understand the possible range of this radioactive element and its effect on rocky planet interior dynamics and potential habitability. The abundances of the radioactive elements Th and U are key components of a planet's energy budget, making up 30% to 50% of the Earth's (Korenaga 2008; All\\`egre et al. 2001; Schubert et al. 1980; Lyubetskaya & Korenaga 2007; The KamLAND Collaboration 2011; Huang et al. 2013). Radiogenic heat drives interior mantle convection and surface plate tectonics, which sustains a deep carbon and water cycle and thereby aides in creating Earth's habitable surface. Unlike other heat sources that are dependent on the planet's specific formation history, the radiogenic heat budget is directly related to the mantle concentration of these nuclides. As a refractory element, the stellar abundance of Th is faithfully reflected in the terrestrial planet's concentration. We find that log eps Th varies from 59%...

  2. Oxygen in Galactic Disk Stars: non-LTE abundances from the 777 nm O I triplet

    E-Print Network [OSTI]

    I. Ramirez; C. Allende Prieto; D. L. Lambert

    2005-06-29T23:59:59.000Z

    Oxygen abundances for a large sample of dwarf and giant stars kinematically selected to be part of the Galactic thin and thick disks have been determined from a non-LTE analysis of the O I triplet lines at 777 nm. The abundance analysis was performed using the infrared flux method temperature scale, trigonometric surface gravities, and accurate atomic data. Within this framework, the ionization balance of iron lines could not be satisfied and so we adopted the iron abundances from Fe II lines only given that they are relatively less sensitive to changes in the atmospheric parameters. We show the resulting [O/Fe] vs. [Fe/H] relationship and briefly discuss its implications.

  3. CHAOS I: Direct Chemical Abundances for HII Regions in NGC 628

    E-Print Network [OSTI]

    Berg, Danielle A; Skillman, Evan D; Pogge, Richard W; Moustakas, John; Groh-Johnson, Mara

    2015-01-01T23:59:59.000Z

    The CHemical Abundances of Spirals (CHAOS) project leverages the combined power of the Large Binocular Telescope (LBT) with the broad spectral range and sensitivity of the Multi Object Double Spectrograph (MODS) to measure "direct" abundances in large samples of HII regions in spiral galaxies. We present LBT MODS observations of 62 HII regions in the nearby NGC628. We measure one or more auroral lines ([OIII] 4363, [NII] 5755, [SIII] 6312, or [OII] 7320,7330) in a large number of HII regions (40). Comparing derived temperatures from multiple auroral line measurements, we find: a strong correlation between temperatures based on [SIII] and [NII]; and large discrepancies for some temperatures based on [OII] and [OIII]. These trends are consistent with other observations in the literature, yet, given the widespread use and acceptance of [OIII] as a temperature determinant, the magnitude of the T[OIII] discrepancies still came as a surprise. Based on these results, we conduct a uniform abundance analysis using the...

  4. Chemo-spectrophotometric evolution of spiral galaxies: III. Abundance and colour gradients in discs

    E-Print Network [OSTI]

    N. Prantzos; S. Boissier

    1999-11-07T23:59:59.000Z

    We study the relations between luminosity and chemical abundance profiles of spiral galaxies, using detailed models for the chemical and spectro-photometric evolution of galactic discs. The models are ``calibrated'' on the Milky Way disc and are successfully extended to other discs with the help of simple ``scaling'' relations, obtained in the framework of semi-analytic models of galaxy formation. We find that our models exhibit oxygen abundance gradients that increase in absolute value with decreasing disc luminosity (when expressed in dex/kpc) and are independent of disc luminosity (when expressed in dex/scalelength), both in agreement with observations. We notice an important strong correlation between abundance gradient and disc scalelength. These results support the idea of ``homologuous evolution'' of galactic discs.

  5. Stellar abundances and molecular hydrogen in high-redshift galaxies -the far-ultraviolet view

    E-Print Network [OSTI]

    William C. Keel

    2006-02-27T23:59:59.000Z

    FUSE spectra of star-forming regions in nearby galaxies are compared to composite spectra of Lyman-break galaxies (LBGs), binned by strength of Lyman alpha emission and by mid-UV luminosity. Several far-UV spectral features, including lines dominated by stellar wind and by photospheric components, are very sensitive to stellar abundances. Their measurement in Lyman-break galaxies is compromised by the strong interstellar absorption features, allowing in some cases only upper limits. The derived C and N abundances in the LBGs are no higher than half solar (scaled to oxygen abundance for comparison with emission-line analyses), independent of the strength of Lyman alpha emission. P V absorption indicates abundances as low as 0.1 solar, with an upper limit near 0.4 solar in the reddest and weakest-emission galaxies. Unresolved interstellar absorption components would further lower the derived abundances. Trends of line strength, and derived abundances, are stronger with mid-UV luminosity than with Lyman-alpha strength. H2 absorption in the Lyman and Werner bands is very weak in the LBGs. Template H2 absorption spectra convolved to appropriate resolution show that strict upper limits N(H2)< 10^18 cm^-2 apply in all cases, with more stringent values appropriate for the stronger-emission composites and for mixes of H2 level populations like those on Milky Way sight lines. Since the UV-bright regions are likely to be widespread in these galaxies, these results rule out massive diffuse reservoirs of H2, and suggest that the dust/gas ratio is already fairly large at z~3.

  6. Early solar mass loss, opacity uncertainties, and the solar abundance problem

    SciTech Connect (OSTI)

    Guzik, Joyce Ann [Los Alamos National Laboratory; Keady, John [Los Alamos National Laboratory; Kilcrease, David [Los Alamos National Laboratory

    2009-01-01T23:59:59.000Z

    Solar models calibrated with the new element abundance mixture of Asplund et al. published in 2005 no longer produce good agreement with the sound speed, convection zone depth, and convection zone helium abundance inferred from solar oscillation data. Attempts to modify the input physics of the standard model, for example, by including enhanced diffusion, increased opacities, accretion, convective overshoot, or gravity waves have not restored the good agreement attained with the prior abundances. Here we present new models including early mass loss via a stronger solar wind. Early mass loss has been investigated prior to the solar abundance problem to deplete lithium and resolve the 'faint early sun problem'. We find that mass loss modifies the core structure and deepens the convection zone, and so improves agreement with oscillation data using the new abundances: however the amount of mass loss must be small to avoid destroying all of the surface lithium, and agreement is not fully restored. We also considered the prospects for increasing solar interior opacities. In order to increase mixture opacities by the 30% required to mitigate the abundance problem, the opacities of individual elements (e.g., O, N, C, and Fe) must be revised by a factor of two to three for solar interior conditions: we are investigating the possibility of broader calculated line wings for bound-bound transitions at the relevant temperatures to enhance opacity. We find that including all of the elements in the AGS05 opacity mixture (through uranium at atomic number Z=92) instead of only the 17 elements in the OPAL opacity mixture increases opacities by a negligible 0.2%.

  7. ATMOSPHERIC COMPOSITION OF WEAK G BAND STARS: CNO AND Li ABUNDANCES

    SciTech Connect (OSTI)

    Adamczak, Jens; Lambert, David L., E-mail: adamczak@astro.as.utexas.edu [McDonald Observatory, University of Texas, Austin, TX 78712 (United States)

    2013-03-10T23:59:59.000Z

    We determined the chemical composition of a large sample of weak G band stars-a rare class of G and K giants of intermediate mass with unusual abundances of C, N, and Li. We have observed 24 weak G band stars with the 2.7 m Harlan J. Smith Telescope at the McDonald Observatory and derived spectroscopic abundances for C, N, O, and Li, as well as for selected elements from Na-Eu. The results show that the atmospheres of weak G band stars are highly contaminated with CN-cycle products. The C underabundance is about a factor of 20 larger than for normal giants and the {sup 12}C/{sup 13}C ratio approaches the CN-cycle equilibrium value. In addition to the striking CN-cycle signature the strong N overabundance may indicate the presence of partially ON-cycled material in the atmospheres of the weak G band stars. The exact mechanism responsible for the transport of the elements to the surface has yet to be identified but could be induced by rapid rotation of the main sequence progenitors of the stars. The unusually high Li abundances in some of the stars are an indicator for Li production by the Cameron-Fowler mechanism. A quantitative prediction of a weak G band star's Li abundance is complicated by the strong temperature sensitivity of the mechanism and its participants. In addition to the unusual abundances of CN-cycle elements and Li, we find an overabundance of Na that is in accordance with the NeNa chain running in parallel with the CN cycle. Apart from these peculiarities, the element abundances in a weak G band star's atmosphere are consistent with those of normal giants.

  8. Seasonal abundance and diversity of ichthyoneuston in the northwestern Gulf of Mexico

    E-Print Network [OSTI]

    Daher, Mary Ann

    1979-01-01T23:59:59.000Z

    SEASONAL ABUNDANCE AND DIVERSITY OF ICHTHYONEUSTON IN THE NORTHWESTERN GULF OF MEXICO A Thesis by MARY ANN DAHER Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER... Committee: Dr. John D. McEachran Larvae of forty-six species of fishes were collected from neuston samples in the northwestern Gulf of Mexico during 1976 and January 1977. 1'h h d p ' * M~l~ht, H~l E . ~N' ' dl dB Ichthyoneuston was more abundant...

  9. Water voles, mink & rabbits So far, the Scottish Highlands have provided water voles with a natural refuge from

    E-Print Network [OSTI]

    Lambin, Xavier

    Water voles, mink & rabbits So far, the Scottish Highlands have provided water voles with a natural, an abundance of rabbits may open the way for an untimely invasion of mink. WATER VOLES, MINK AND RABBITS W hen re-introducing extinct species is on the conservation agenda, the prospect of losing the water vole

  10. Tin Anode for Sodium-Ion Batteries Using Natural Wood Fiber as a Mechanical Buffer and Electrolyte Reservoir

    E-Print Network [OSTI]

    Li, Teng

    Tin Anode for Sodium-Ion Batteries Using Natural Wood Fiber as a Mechanical Buffer and Electrolyte Information ABSTRACT: Sodium (Na)-ion batteries offer an attractive option for low cost grid scale storage due to the abundance of Na. Tin (Sn) is touted as a high capacity anode for Na-ion batteries with a high theoretical

  11. Welcome FUPWG- Natural Gas Overview

    Broader source: Energy.gov [DOE]

    Presentation—given at the Federal Utility Partnership Working Group (FUPWG) Fall 2008 meeting—provides an overview of natural gas, including emissions, compressed natural gas (CNG) vehicles, and landfill gas supplement for natural gas system.

  12. Oxygen, {\\alpha}-element and iron abundance distributions in the inner part of the Galactic thin disc

    E-Print Network [OSTI]

    Martin, R P; Kovtyukh, V V; Korotin, S A; Yegorova, I A; Saviane, Ivo

    2015-01-01T23:59:59.000Z

    We derived elemental abundances in 27 Cepheids, the great majority situated within a zone of Galactocentric distances ranging from 5 to 7 kpc. One star of our sample, SU Sct, has a Galactocentric distance of about 3 kpc, and thus falls in a poorly investigated region of the inner thin disc. Our new results, combined with data on abundances in the very central part of our Galaxy taken from literature, show that iron, magnesium, silicon, sulfur, calcium and titanium LTE abundance radial distributions, as well as NLTE distribution of oxygen reveal a plateau-like structure or even positive abundance gradient in the region extending from the Galactic center to about 5 kpc.

  13. Natural Gas | Department of Energy

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

    Fossil Natural Gas Natural Gas September 15, 2014 NETL Releases Hydraulic Fracturing Study The National Energy Technology Laboratory has released a technical report on the...

  14. Historical Natural Gas Annual 1999

    U.S. Energy Information Administration (EIA) Indexed Site

    1999 The Historical Natural Gas Annual contains historical information on supply and disposition of natural gas at the national, regional, and State level as well as prices at...

  15. Intervention Analysis of Hurricane Effects on Snail Abundance in a Tropical Forest Using

    E-Print Network [OSTI]

    Willig, Michael

    Intervention Analysis of Hurricane Effects on Snail Abundance in a Tropical Forest Using Long disturbances, such as hurricanes, have profound effects on pop- ulations, either directly by causing mortality of resources. In the last 20 years, two major disturbances, Hurricane Hugo in 1989 and Hurricane Georges

  16. Solar Cells from Earth-Abundant Semiconductors with Plasmon-Enhanced Light Absorption

    SciTech Connect (OSTI)

    Atwater, Harry

    2012-04-30T23:59:59.000Z

    Progress is reported in these areas: Plasmonic Light Trapping in Thin Film a-Si Solar Cells; Plasmonic Light Trapping in Thin InGaN Quantum Well Solar Cells; and Earth Abundant Cu{sub 2}O and Zn{sub 3}P{sub 2} Solar Cells.

  17. Rapid Communication Herpes simplex virus 1 microRNAs expressed abundantly during latent infection are

    E-Print Network [OSTI]

    Knipe, David M.

    Rapid Communication Herpes simplex virus 1 microRNAs expressed abundantly during latent infection Available online 23 July 2011 Keywords: Herpes simplex virus MicroRNAs Latency Gene regulation Several herpes simplex virus 1 microRNAs are encoded within or near the latency associated transcript (LAT) locus

  18. Sulfur, Chlorine, and Argon Abundances in Planetary Nebulae. III: Observations and Results for a Final Sample

    E-Print Network [OSTI]

    K. B. Kwitter; R. B. C. Henry; J. B. Milingo

    2002-09-25T23:59:59.000Z

    This paper is the fourth in a series whose purpose is to study the interstellar abundances of sulfur, chlorine, and argon in the Galaxy using a sample of 86 planetary nebulae. Here we present new high-quality spectrophotometric observations of 20 Galactic planetary nebulae with spectral coverage from 3700-9600 Angstroms. A major feature of our observations throughout the entire study has been the inclusion of the near-infrared lines of [S III] 9069,9532, which allows us to calculate accurate S+2 abundances and to either improve upon or convincingly confirm results of earlier sulfur abundance studies. For each of the 20 objects here we calculate ratios of S/O, Cl/O, and Ar/O and find average values of S/O=1.1E-2+/-1.1E-2, Cl/O=4.2E-4+/-5.3E-4, and Ar/O=5.7E-3+/-4.3E-3. For six objects we are able to compare abundances of S+3 calculated directly from available [S IV] 10.5 micron measurements with those inferred indirectly from the values of the ionization correction factors for sulfur. In the final paper of the series, we will compile results from all 86 objects, search for and evaluate trends, and use chemical evolution models to interpret our results.

  19. Seeding the Pregenetic Earth: Meteoritic Abundances of Nucleobases and Potential Reaction Pathways

    E-Print Network [OSTI]

    Pearce, Ben K D

    2015-01-01T23:59:59.000Z

    Carbonaceous chondrites are a class of meteorite known for having a high content of water and organics. In this study, abundances of the nucleobases, i.e., the building blocks of RNA and DNA, found in carbonaceous chondrites are collated from a variety of published data and compared across various meteorite classes. An extensive review of abiotic chemical reactions producing nucleobases is then performed. These reactions are then reduced to a list of 15 individual reaction pathways that could potentially occur within meteorite parent bodies. The nucleobases guanine, adenine and uracil are found in carbonaceous chondrites in the amounts of 1$-$500 ppb. It is currently unknown which reaction is responsible for their synthesis within the meteorite parent bodies. One class of carbonaceous meteorites dominate the abundances of both amino acids and nucleobases$-$the so-called CM2 (e.g. Murchison meteorite). CR2 meteorites (e.g. Graves Nunataks) also dominate the abundances of amino acids, but are the least abundant...

  20. Bringing you a prosperous future where energy is clean, abundant, reliable and affordable Industrial Technologies Program

    E-Print Network [OSTI]

    Beckermann, Christoph

    Industrial Technologies Program U.S. Department of Energy Office of Energy Efficiency and Renewable Energy of Energy Efficiency and Renewable Energy invests in a diverse portfolio of energy technologies. For moreBringing you a prosperous future where energy is clean, abundant, reliable and affordable

  1. The Effects of Disturbance Events on Abundance and Sex Ratios of a Terrestrial Turtle, Terrapene bauri

    E-Print Network [OSTI]

    Oli, Madan K.

    without catastrophic mortality, survivorship could be reduced following a disturbance, thus leading long-term effect on abundance as long as initial mortality is not severe and food resources remain. 2003). Both large (e.g., hurricanes) and small (e.g., wind damage in forested habitats) scale

  2. FOREST STRUCTURE AND PREY ABUNDANCE IN WINTER HABITAT OF NORTHERN GOSHAWKS

    E-Print Network [OSTI]

    Beier, Paul

    suited to goshawk maneu- verability and hunting behavior) is more important than prey abundance. During their breeding-season home ranges in ponderosa pine forest during winter. Meanwhile, most males moved into lower squirrel [Sciurus aberti]). Goshawks minimized energy expense and thermal exposure of flight by caching

  3. Monitoring Butterfly Abundance: Beyond Pollard Walks Jero^ me Pellet1,2

    E-Print Network [OSTI]

    Richner, Heinz

    Monitoring Butterfly Abundance: Beyond Pollard Walks Je´ro^ me Pellet1,2 *, Jason T. Bried3 , David to the characteristics of the species under scrutiny and resources availability. Citation: Pellet J, Bried JT, Parietti D Copyright: � 2012 Pellet et al. This is an open-access article distributed under the terms of the Creative

  4. Abundance, Composition, and Sinking Rates of Fish Fecal Pellets in the Santa

    E-Print Network [OSTI]

    Abundance, Composition, and Sinking Rates of Fish Fecal Pellets in the Santa Barbara Channel Grace.O. Box 1346, Gloucester Point, Virginia 23062, USA. Rapidly sinking fecal pellets are an important composition, particulate organic carbon/nitrogen (POC/PON), and sinking rates of fecal pellets produced

  5. EARTH ABUNDANT MATERIALS FOR HIGH EFFICIENCY HETEROJUNCTION THIN FILM SOLAR CELLS

    E-Print Network [OSTI]

    Ceder, Gerbrand

    materials for thin film solar cells such as CdTe and CIGS suffer from concerns over resource scarcity (eEARTH ABUNDANT MATERIALS FOR HIGH EFFICIENCY HETEROJUNCTION THIN FILM SOLAR CELLS Yun Seog Lee 1 conversion efficiencies should be increased. In terms of reducing module cost, thin film solar cells

  6. ON THE ABUNDANCE OF PRESOLAR SILICATE AND OXIDE GRAINS IN PRIMITIVE METEORITES.

    E-Print Network [OSTI]

    ON THE ABUNDANCE OF PRESOLAR SILICATE AND OXIDE GRAINS IN PRIMITIVE METEORITES. A. Nguyen1 , E of presolar silicates in IDPs and meteorites [1-3] has opened new opportunities. Isotopic analyses of elements for presolar silicates to the CO3.0 meteorite ALH77307. This search resulted in the discovery of 9 presolar

  7. Simulations of water isotope abundances in the upper troposphere and lower stratosphere and implications

    E-Print Network [OSTI]

    Gettelman, Andrew

    fractionation processes. The results indicate that water substance in the upper troposphere does not follow a Rayleigh distillation model due to the presence of condensed phase water. Stratospheric abundances and climate of the upper troposphere and lower stratosphere (UT/LS). It is broadly known that most of the air

  8. ABUNDANCE AND VERTICAL DISTRIBUTION OF FISHES IN A COBBLE-BOTTOM KELP FOREST OFF

    E-Print Network [OSTI]

    ABUNDANCE AND VERTICAL DISTRIBUTION OF FISHES IN A COBBLE-BOTTOM KELP FOREST OFF SAN ONOFRE composition,vertical distribution,and standingstockoffishes ina forest of giant kelp and a nearby kelp substrates, were rare or absent in these low-relief, cobble- bottom habitats. The species present in the kelp

  9. Nucleosynthesis and mixing on the Asymptotic Giant Branch. III. Predicted and observed s-process abundances

    E-Print Network [OSTI]

    M. Busso; R. Gallino; D. L. Lambert; C. Travaglio; V. V. Smith

    2001-04-26T23:59:59.000Z

    We present the results of s-process nucleosynthesis calculations for AGB stars of different metallicities and initial masses. The computations were based on previously published stellar evolutionary models that account for the III dredge up phenomenon occurring late on the AGB. Neutron production is driven by the 13C(alpha,n)16O reaction during the interpulse periods in a tiny layer in radiative equilibrium at the top of the He- and C-rich shell. The s-enriched material is subsequently mixed with the envelope by the III dredge up, and the envelope composition is computed after each thermal pulse. We follow the changes in the photospheric abundance of the Ba-peak elements (heavy s, or `hs') and that of the Zr-peak ones (light s, or `ls'), whose logarithmic ratio [hs/ls] has often been adopted as an indicator of the s-process efficiency. The theoretical predictions are compared with published abundances of s elements for Galactic AGB giants of classes MS, S, SC, post-AGB supergiants, and for various classes of binary stars. The observations in general confirm the complex dependence of n captures on metallicity. They suggest that a moderate spread exists in the abundance of 13C that is burnt in different stars. Although additional observations are needed, a good understanding has been achieved of s-process operation in AGB. The detailed abundance distribution including the light elements (CNO) of a few s-enriched stars at different metallicity are examined.

  10. Complex hydraulic and substrate variables limit freshwater mussel species richness and abundance

    E-Print Network [OSTI]

    Vaughn, Caryn

    Complex hydraulic and substrate variables limit freshwater mussel species richness and abundance. We examined how substrate and complex hydraulic variables limit the distribution of freshwater mussels. We sampled mussels and measured substrate and hydraulic variables (at low and high flows) at 6

  11. Bacterial traits, organism mass, and numerical abundance in the detrital soil food web of Dutch

    E-Print Network [OSTI]

    Cohen, Joel E.

    M and numerical abundance N. The microbial biomass and biodiversity of belowground fauna were and fragmentation. The quantity and diversity of litter are traditionally considered the bottom-up controlling donor). As the microbial biomass comprises the majority of the total biomass in soil, the role of top-down regulation

  12. Oxygen Abundances in the Milky Way Using X-ray Absorption Measurements Towards Galaxy Clusters

    E-Print Network [OSTI]

    Wayne H. Baumgartner; Richard F. Mushotzky

    2005-09-21T23:59:59.000Z

    We present measurements of the oxygen abundance of the Milky Way's ISM by observing the K-shell X-ray photoionization edge towards galaxy clusters. This effect is most easily observed towards objects with galactic columns (n_H) of a few times 1e21 cm^-2. We measure X-ray column densities towards 11 clusters and find that at high galactic columns above approximately 1e21 cm^-2 the X-ray columns are generally 1.5--3.0 times greater than the 21 cm H II columns, indicating that molecular clouds become an important contributor to n_H at higher columns. We find the average ISM oxygen abundance to be (O/H) = (4.85 +/- 0.06) x 10^-4, or 0.99 solar when using the most recent solar photospheric values. Since X-ray observations are sensitive to the total amount of oxygen present (gas + dust), these results indicate a high gas to dust ratio. Also, the oxygen abundances along lines of sight through high galactic columns (n_H) are the same as abundances through low columns, suggesting that the composition of denser clouds is similar to that of the more diffuse ISM.

  13. Using benthic infauna abundance and genetic markers in oysters as indicators of hypoxia downstream from a

    E-Print Network [OSTI]

    Vallino, Joseph J.

    Using benthic infauna abundance and genetic markers in oysters as indicators of hypoxia downstream on communities downstream from these systems has not been well assessed. This study sought to examine differences between regions downstream from a permeable reactive barrier and a control site at Waquoit Bay in three

  14. Deep-Sea Research II 52 (2005) 799822 Top predator distribution and abundance across the

    E-Print Network [OSTI]

    in abundance in the oceanic zone in 1998, 2001, and 2002, owing primarily to influxes of dark shearwaters 0967-0645/$ - see front matter r 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.dsr2 and location of water masses strong

  15. NREL Highlights SCIENCE Use of Earth-abundant materials in solar absorber films

    E-Print Network [OSTI]

    NREL Highlights SCIENCE Use of Earth-abundant materials in solar absorber films is critical was proposed more than 25 years ago in the form of FeS2 pyrite--fool's gold. Unfortunately, the material has that can be used to identify new Fe-containing materials that can circumvent the limitations of FeS2 pyrite

  16. Abundance and species composition of amphibians, small mammals, and songbirds in

    E-Print Network [OSTI]

    Macdonald, Ellen

    buffer strips are left along water bodies after forest harvesting to protect water quality and fish report on changes in terrestrial vertebrate communities from pre- to post-harvest in experimentally levels, 3 replicates) before and after harvesting. Changes in small mammal or amphibian abundance were

  17. C/O abundance ratios, iron depletions, and infrared dust features in Galactic planetary nebulae

    E-Print Network [OSTI]

    Delgado-Inglada, Gloria

    2014-01-01T23:59:59.000Z

    We study the dust present in 56 Galactic planetary nebulae (PNe) through their iron depletion factors, their C/O abundance ratios (in 51 objects), and the dust features that appear in their infrared spectra (for 33 objects). Our sample objects have deep optical spectra of good quality, and most of them also have ultraviolet observations. We use these observations to derive the iron abundances and the C/O abundance ratios in a homogeneous way for all the objects. We compile detections of infrared dust features from the literature and we analyze the available Spitzer/IRS spectra. Most of the PNe have C/O ratios below one and show crystalline silicates in their infrared spectra. The PNe with silicates have C/O < 1, with the exception of Cn 1-5. Most of the PNe with dust features related to C-rich environments (SiC or the 30 {\\mu}m feature usually associated to MgS) have C/O $\\gtrsim$ 0.8. PAHs are detected over the full range of C/O values, including 6 objects that also show silicates. Iron abundances are low...

  18. Spatial pattern and temporal dynamics of northern bobwhite abundance and agricultural landuse, and potential casual factors

    E-Print Network [OSTI]

    Okay, Atiye Zeynep

    2006-04-12T23:59:59.000Z

    further intensified during World War II and the years following the war. These land use changes had overall negative effects on NBW habitat. Analysis of the changes in spatial pattern of NBW abundance in the Great Plains region during the severe drought...

  19. RESIK Solar X-ray flare element abundances on a non-isothermal assumption

    E-Print Network [OSTI]

    Sylwester, B; Sylwester, J; Kepa, A

    2015-01-01T23:59:59.000Z

    Solar X-ray spectra from the RESIK crystal spectrometer on the {\\em CORONAS-F} spacecraft (spectral range $3.3-6.1$~\\AA) are analyzed for thirty-three flares using a method to derive abundances of Si, S, Ar, and K, emission lines of which feature prominently in the spectra. For each spectrum, the method first optimizes element abundances then derives the differential emission measure as a function of temperature based on a procedure given by Sylwester et al. and Withbroe. This contrasts with our previous analyses of RESIK spectra in which an isothermal assumption was used. The revised abundances (on a logarithmic scale with $A({\\rm H}) = 12$) averaged for all the flares in the analysis are $A({\\rm Si}) = 7.53 \\pm 0.08$ (previously $7.89 \\pm 0.13$), $A({\\rm S}) = 6.91 \\pm 0.07$ ($7.16 \\pm 0.17$), $A({\\rm Ar}) = 6.47 \\pm 0.08$ ($6.45 \\pm 0.07$), and $A({\\rm K}) = 5.73 \\pm 0.19$ ($5.86 \\pm 0.20$), with little evidence for time variations of abundances within the evolution of each flare. Our previous estimates of...

  20. Parvalbumin 3 is an Abundant Ca2+ Buffer in Hair Cells

    E-Print Network [OSTI]

    Hudspeth, A. James

    Parvalbumin 3 is an Abundant Ca2+ Buffer in Hair Cells STEFAN HELLER,* ANDREA M. BELL, CHARLOTTE S parts of a hair cell. The Ca2+ concentration in ste- reocilia regulates adaptation and, through rapid saccular and chicken cochlear hair cells. We cloned cDNAs en- coding this protein from the corresponding

  1. The solar photospheric abundance of europium. Results from CO5BOLD 3-D hydrodynamical model atmospheres

    E-Print Network [OSTI]

    A. Mucciarelli; E. Caffau; B. Freytag; H. -G. Ludwig; P. Bonifacio

    2008-03-06T23:59:59.000Z

    Context. Europium is an almost pure r-process element, which may be useful as a reference in nucleocosmochronology. Aims. To determine the photospheric solar abundance using CO5BOLD 3-D hydrodynamical model atmospheres. Methods. Disc-centre and integrated-flux observed solar spectra are used. The europium abundance is derived from the equivalent width measurements. As a reference 1D model atmospheres have been used, in addition. Results. The europium photospheric solar abundance is 0.52 +- 0.02 in agreement with previous determinations. We also determine the photospheric isotopic fraction of Eu(151) to be 49 % +- 2.3 % from the intensity spectra and 50% +-2.3 from the flux spectra. This compares well to the the meteoritic isotopic fraction 47.8%. We explore the 3D corrections also for dwarfs and sub-giants in the temperature range ~5000 K to ~6500 K and solar and 1/10--solar metallicities and find them to be negligible for all the models investigated. Conclusions. Our photospheric Eu abundance is in good agreement with previous determinations based on 1D models. This is in line with our conclusion that 3D effects for this element are negligible in the case of the Sun.

  2. The solar photospheric abundance of europium. Results from CO5BOLD 3-D hydrodynamical model atmospheres

    E-Print Network [OSTI]

    Mucciarelli, A; Freytag, B; Ludwig, H -G; Bonifacio, P

    2008-01-01T23:59:59.000Z

    Context. Europium is an almost pure r-process element, which may be useful as a reference in nucleocosmochronology. Aims. To determine the photospheric solar abundance using CO5BOLD 3-D hydrodynamical model atmospheres. Methods. Disc-centre and integrated-flux observed solar spectra are used. The europium abundance is derived from the equivalent width measurements. As a reference 1D model atmospheres have been used, in addition. Results. The europium photospheric solar abundance is 0.52 +- 0.02 in agreement with previous determinations. We also determine the photospheric isotopic fraction of Eu(151) to be 49 % +- 2.3 % from the intensity spectra and 50% +-2.3 from the flux spectra. This compares well to the the meteoritic isotopic fraction 47.8%. We explore the 3D corrections also for dwarfs and sub-giants in the temperature range ~5000 K to ~6500 K and solar and 1/10--solar metallicities and find them to be negligible for all the models investigated. Conclusions. Our photospheric Eu abundance is in good agre...

  3. Abundance gradients in the Milky Way for alpha elements, Iron peak elements, Barium, Lanthanum and Europium

    E-Print Network [OSTI]

    G. Cescutti; F. Matteucci; P. Francois; C. Chiappini

    2006-09-29T23:59:59.000Z

    We model the abundance gradients in the disk of the Milky Way for several chemical elements (O, Mg, Si, S, Ca, Sc, Ti, Co, V, Fe, Ni, Zn, Cu, Mn, Cr, Ba, La and Eu), and compare our results with the most recent and homogeneous observational data. We adopt a chemical evolution model able to well reproduce the main properties of the solar vicinity. We compute, for the first time, the abundance gradients for all the above mentioned elements in the galactocentric distance range 4 - 22 kpc. The comparison with the observed data on Cepheids in the galactocentric distance range 5-17 kpc gives a very good agreement for many of the studied elements. In addition, we fit very well the data for the evolution of Lanthanum in the solar vicinity for which we present results here for the first time. We explore, also for the first time, the behaviour of the abundance gradients at large galactocentric distances by comparing our results with data relative to distant open clusters and red giants and select the best chemical evolution model model on the basis of that. We find a very good fit to the observed abundance gradients, as traced by Cepheids, for most of the elements, thus confirming the validity of the inside-out scenario for the formation of the Milky Way disk as well as the adopted nucleosynthesis prescriptions.

  4. Natural warm inflation

    SciTech Connect (OSTI)

    Visinelli, Luca, E-mail: u0583682@utah.edu [Department of Physics and Astronomy, University of Utah, 115 South 1400 East 201, Salt Lake City, Utah 84112-0830 (United States)

    2011-09-01T23:59:59.000Z

    We derive the requirements that a generic axion-like field has to satisfy in order to play the role of the inflaton field in the warm inflation scenario. Compared to the parameter space in ordinary Natural Inflation models, we find that the parameter space in our model is enlarged. In particular, we avoid the problem of having an axion decay constant f that relates to the Planck scale, which is instead present in the ordinary Natural Inflation models; in fact, our model can easily accommodate values of the axion decay constant that lie well below the Planck scale.

  5. Go Abroad in Natural ResourcesNatural Resources

    E-Print Network [OSTI]

    Escher, Christine

    Go Abroad in Natural ResourcesNatural Resources Program Contact: Connie Patterson Program.edu/ international The Natural Resources degree is ideally suited for students who wish to study abroad! The sustainable management of natural resources is a fundamental issue, both locally and globally. Scientists

  6. Fundamental Parameters and Abundances of Metal-Poor Stars: The SDSS Standard BD +17 4708

    E-Print Network [OSTI]

    I. Ramirez; C. Allende Prieto; S. Redfield; D. L. Lambert

    2006-08-25T23:59:59.000Z

    The atmospheric parameters and iron abundance of the Sloan Digital Sky Survey (SDSS) spectrophotometric standard star BD +17 4708 are critically examined using up-to-date Kurucz model atmospheres, LTE line formation calculations, and reliable atomic data. We find Teff = 6141+-50 K, log g = 3.87+-0.08, and [Fe/H]=-1.74+-0.09. The line-of-sight interstellar reddening, bolometric flux, limb-darkened angular diameter, stellar mass, and the abundances of Mg, Si, and Ca are also obtained. This star is a unique example of a moderately metal-poor star for which the effective temperature can be accurately constrained from the observed spectral energy distribution (corrected for reddening). Such analysis leads to a value that is higher than most spectroscopic results previously reported in the literature (~5950 K). We find that the ionization balance of Fe lines is satisfied only if a low Teff (~5950 K) is adopted. With our preferred Teff (6141 K), the mean iron abundance we obtain from the FeII lines is lower by about 0.15 dex than that from the FeI lines, and therefore, the discrepancy between the mean iron abundance from FeI and FeII lines cannot be explained by overionization by UV photons as the main non-LTE effect. We also comment on non-LTE effects and the importance of inelastic collisions with neutral H atoms in the determination of oxygen abundances in metal-poor stars from the 777 nm OI triplet. (Abridged)

  7. Natural Gas Purchasing Options

    E-Print Network [OSTI]

    Watkins, G.

    As a result of economic and regulatory changes, the natural gas marketplace now offers multiple options for purchasers. The purpose of this panel is to discuss short-term purchasing options and how to take advantage of these options both to lower...

  8. Saving Natural Inflation

    E-Print Network [OSTI]

    Djuna Croon; Veronica Sanz

    2015-01-12T23:59:59.000Z

    Slow-roll inflation requires the inflaton field to have an exceptionally flat potential, which combined with measurements of the scale of inflation demands some degree of fine-tuning. Alternatively, the flatness of the potential could be due to the inflaton's origin as a pseudo-Goldstone boson, as in Natural Inflation. Alas, consistency with Planck data places the original proposal of Natural Inflation in a tight spot, as it requires a trans-Planckian excursion of the inflaton. Although one can still tune the renormalizable potential to sub-Planckian values, higher order corrections from quantum gravity or sources of breaking of the Goldstone symmetry would ruin the predictivity of the model. In this paper we show how in more realistic models of Natural Inflation one could achieve inflation without a trans-Planckian excursion of the field. We show how a variant of Extra-natural inflation with bulk fermions can achieve the desired goal and discuss its four-dimensional duals. We also present a new type of four dimensional models inspired in Little Higgs and Composite Higgs models which can lead to sub-Planckian values of the inflaton field.

  9. Natural Gas Purchasing Options 

    E-Print Network [OSTI]

    Watkins, G.

    1988-01-01T23:59:59.000Z

    As a result of economic and regulatory changes, the natural gas marketplace now offers multiple options for purchasers. The purpose of this panel is to discuss short-term purchasing options and how to take advantage of these options both to lower...

  10. STEWARDSHIP MAINTAINING NATURAL RICHES

    E-Print Network [OSTI]

    Ford, James

    ;Outstanding Results 5 Energy Conservation: Saved 240 Million KWH over last fifteen years. Green BuildingLAND STEWARDSHIP MAINTAINING NATURAL RICHES TRANSPORTATION GOING THE EXTRA MILE GREEN BUILDING SHOWCASING INNOVATION WATER CONSERVING PRESCIOUS RESOURCES ENERGY MOVING TO A BRIGHTER FUTURE WASTE REDUCING

  11. warnell school Forestry & Natural Resources

    E-Print Network [OSTI]

    Hall, Daniel

    #12;#12;warnell school Forestry & Natural Resources 2009 Annual Report o #12;VisionTo be recognized as one of the top five forestry and natural resource programs in the United States. Mission's renewable natural resources; and to place latest ideas and technology in forestry and natural resource

  12. Nature Conservancy University of Ottawa

    E-Print Network [OSTI]

    Blouin-Demers, Gabriel

    . Natural Area Conservation Planning. 5. Natural Area Plan for the Frontenac Arch. 6. Management Planning is enough? Less than 10% of Canada's natural lands are in protected status. #12; Conservation of Private. The Conservancy is a non- advocacy, non- confrontational, private lands organization. Natural Area Property

  13. Estimating and decomposing total uncertainty for survey-based abundance estimates of Norwegian spring-spawning herring

    E-Print Network [OSTI]

    Aldrin, Magne

    the Norwegian coast, feed in the Norwegian Sea and adjacent areas, and overwinter in various partsEstimating and decomposing total uncertainty for survey-based abundance estimates of Norwegian uncertainty for survey-based abundance estimates of Norwegian spring-spawning herring. ­ ICES Journal

  14. SOLAR WIND HELIUM ABUNDANCE AS A FUNCTION OF SPEED AND HELIOGRAPHIC LATITUDE: VARIATION THROUGH A SOLAR CYCLE

    E-Print Network [OSTI]

    Richardson, John

    SOLAR WIND HELIUM ABUNDANCE AS A FUNCTION OF SPEED AND HELIOGRAPHIC LATITUDE: VARIATION THROUGH of the variation of the relative abundance of helium to hydrogen in the solar wind as a function of solar wind theoretical work in which enhancements of coronal helium lead to stagnation of the escaping proton flux

  15. OXYGEN ABUNDANCE OF OPEN CLUSTER DWARFS Department of Astronomy, Peking University, Beijing 100871, China; shenzx@bac.pku.edu.cn

    E-Print Network [OSTI]

    Liu, Xiaowei

    OXYGEN ABUNDANCE OF OPEN CLUSTER DWARFS Z.-X. Shen Department of Astronomy, Peking University 100871, China Received 2005 June 30; accepted 2007 January 19 ABSTRACT We present oxygen abundances in the open cluster Pleiades derived from the [O i] k6300 forbidden line. Stellar parameters and oxygen

  16. Chemical abundances in the extremely carbon-rich and xenon-rich halo planetary nebula H4-1

    SciTech Connect (OSTI)

    Otsuka, Masaaki [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China); Tajitsu, Akito, E-mail: otsuka@asiaa.sinica.edu.tw, E-mail: tajitsu@subaru.naoj.org [Subaru Telescope, NAOJ, 650 North A'ohoku Place, Hilo, HI 96720 (United States)

    2013-12-01T23:59:59.000Z

    We performed detailed chemical abundance analysis of the extremely metal-poor ([Ar/H] ? –2) halo planetary nebula (PN) H4-1 based on the multi-wavelength spectra from Subaru/HDS, GALEX, SDSS, and Spitzer/IRS and determined the abundances of 10 elements. The C and O abundances were derived from collisionally excited lines (CELs) and are almost consistent with abundances from recombination lines (RLs). We demonstrated that the large discrepancy in the C abundance between CEL and RL in H4-1 can be solved using the temperature fluctuation model. We reported the first detection of the [Xe III] ?5846 line in H4-1 and determination of its elemental abundance ([Xe/H] > +0.48). H4-1 is the most Xe-rich PN among the Xe-detected PNe. The observed abundances are close to the theoretical prediction by a 2.0 M {sub ?} single star model with an initially element rich ([r/Fe] = +2.0 dex) rapid neutron-capture process (r-process). The observed Xe abundance would be a product of the r-process in primordial supernovae. The [C/O]-[Ba/(Eu or Xe)] diagram suggests that the progenitor of H4-1 shares the evolution with carbon-enhanced metal-poor (CEMP)-r/s and CEMP-no stars. The progenitor of H4-1 is presumably a binary formed in an r-process-rich environment.

  17. THE ABUNDANCE OF CARBON DIOXIDE ICE IN THE QUIESCENT INTRACLOUD MEDIUM D. C. B. Whittet,1,2

    E-Print Network [OSTI]

    Gerakines, Perry

    THE ABUNDANCE OF CARBON DIOXIDE ICE IN THE QUIESCENT INTRACLOUD MEDIUM D. C. B. Whittet,1,2 S. S: ISM: lines and bands -- ISM: molecules 1. INTRODUCTION Carbon dioxide (CO2) has proven to be a common embedded sources. Key properties include abundance relative to other ice constituents and dust extinction

  18. Natural Dark Energy

    E-Print Network [OSTI]

    Douglas Scott; Ali Frolop

    2007-03-30T23:59:59.000Z

    It is now well accepted that both Dark Matter and Dark Energy are required in any successful cosmological model. Although there is ample evidence that both Dark components are necessary, the conventional theories make no prediction for the contributions from each of them. Moreover, there is usually no intrinsic relationship between the two components, and no understanding of the nature of the mysteries of the Dark Sector. Here we suggest that if the Dark Side is so seductive then we should not be restricted to just 2 components. We further suggest that the most natural model has 5 distinct forms of Dark Energy in addition to the usual Dark Matter, each contributing precisely equally to the cosmic energy density budget.

  19. Natural gas repowering experience

    SciTech Connect (OSTI)

    Bautista, P.J.; Fay, J.M. [Gas Research Institute, Chicago, IL (United States); Gerber, F.B. [BENTEK Energy Research, DeSoto, TX (United States)

    1995-12-31T23:59:59.000Z

    Gas Research Institute has led a variety of projects in the past two years with respect to repowering with natural gas. These activities, including workshops, technology evaluations, and market assessments, have indicated that a significant opportunity for repowering exists. It is obvious that the electric power industry`s restructuring and the actual implementation of environmental regulations from the Clean Air Act Amendments will have significant impact on repowering with respect to timing and ultimate size of the market. This paper summarizes the results and implications of these activities in repowering with natural gas. It first addresses the size of the potential market and discusses some of the significant issues with respect to this market potential. It then provides a perspective on technical options for repowering which are likely to be competitive in the current environment. Finally, it addresses possible actions by the gas industry and GRI to facilitate development of the repowering market.

  20. Natural Cooling Retrofit

    E-Print Network [OSTI]

    Fenster, L. C.; Grantier, A. J.

    1981-01-01T23:59:59.000Z

    Figure V). Tower Water Injection Natural Cool ing consists of crossover piping between the chillers, condenser and chiller water piping, switching valves, con trols, a strainer and/or a filtration system, and a water treatment system, in addition..., if not impera tive, to utilize a combination of strainers, filters, and/or sophisticated water treatment to ensure that the thermal efficiency of the chilled water system is not degraded due to scal ing, corro sion, and microbial growth. A routine water...

  1. Nature's Greatest Puzzles

    SciTech Connect (OSTI)

    Quigg, Chris; /Fermilab

    2005-02-01T23:59:59.000Z

    It is a pleasure to be part of the SLAC Summer Institute again, not simply because it is one of the great traditions in our field, but because this is a moment of great promise for particle physics. I look forward to exploring many opportunities with you over the course of our two weeks together. My first task in talking about Nature's Greatest Puzzles, the title of this year's Summer Institute, is to deconstruct the premise a little bit.

  2. Chlorophylls - natural solar cells

    E-Print Network [OSTI]

    Jantschi, Lorentz; Balan, Mugur C; Sestras, Radu E

    2011-01-01T23:59:59.000Z

    A molecular modeling study was conducted on a series of six natural occurring chlorophylls. Quantum chemistry calculated orbital energies were used to estimate frequency of transitions between occupied molecular orbital and unoccupied molecular orbital energy levels of chlorophyll molecules in vivo conditions in standard (ASTMG173) environmental conditions. Obtained results are in good agreement with energies necessary to fix the Magnesium atom by chlorophyll molecules and with occurrence of chlorophylls in living vegetal organisms.

  3. Texas' Natural Lake

    E-Print Network [OSTI]

    Wythe, Kathy

    2006-01-01T23:59:59.000Z

    in Texas A&M?s Department of Wildlife and Fisheries Sciences, said the summary report synthesizes the ?state of knowl- edge? about the geography, hydrology, ecology and environmental impacts affecting Caddo Lake and Big Cypress Creek. At the second...; and heavy metals, including mercury found in the lignite coal used to power electricity-generating plants, are accumulating in fish tissues. Texas? Natural Lake tx H2O | pg. 2 Research to help restore environmental flows to Caddo Lake Scientists...

  4. Constraints on the relic neutrino abundance and implications for cosmological neutrino mass limits

    SciTech Connect (OSTI)

    Bell, Nicole F.; /Fermilab

    2004-01-01T23:59:59.000Z

    The authors examine a mechanism which can lead to flavor transformation of neutrino-antineutrino asymmetries in the early universe, a process which is unavoidable when the neutrino mixing angles are large. This sets the best limit on the lepton number of the universe, and hence on the relic neutrino abundance. They also consider the consequences for the relic neutrino abundance if extra neutrino interactions are allowed, e.g., the coupling of the neutrinos to a light (compared to m{sub {nu}}) boson. For a wide range of couplings not excluded by other considerations, the relic neutrinos would annihilate to bosons at late times, and thus make a negligible contribution to the matter density today. This mechanism evades the neutrino mass limits arising from large scale structure.

  5. Abundances of sulfur, chlorine, and trace elements in Illinois Basin coals, USA

    SciTech Connect (OSTI)

    Chou, C.L. [Illinois State Geological Survey, Champaign, IL (United States)

    1997-12-31T23:59:59.000Z

    Abundances of sulfur, chlorine and 52 trace elements in 220 channel and drill-core samples of high volatile bituminous coals (Pennsylvanian age) from the Illinois Basin, USA, are evaluated for the purpose of better understanding geologic processes affecting trace element variation in the coal seams. Mean elemental abundances in Illinois Basin coals are listed in a table. Most Illinois Basin coals are high-sulfur (> 3% total sulfur). Peat was influenced by seawater during early diagenesis. However, low-medium sulfur coal (<3% total sulfur) occurs in restricted areas along the Walshville Channel, which is a contemporaneous river in the peat swamp. A comparison of trace element abundances between high-sulfur and low-medium sulfur coals showed that only seven elements (boron, sulfur, iron, molybdenum, mercury, thallium, and uranium) are clearly more abundant in high-sulfur coal than in low-medium sulfur coal. Apparently, boron, sulfur, molybdenum, and uranium in high-sulfur coals were derived from seawater that inundated the peat swamp and terminated peat accumulation. Iron, mercury, and thallium had a terrestrial source and were incorporated in pyrite during diagenesis. Their enrichment in high-sulfur coal is related to pyrite formation in a reducing environment. The chlorine content in Illinois Basin coals, including channel and drill core samples, varies from 0.01% to 0.8% (on a dry basis). Coal samples from surface mines (< 50 meter depth) are usually low in chlorine content (<0.1%). Samples from underground mines (> 50 meter depth) have a chlorine content ranging between 0.1% to 0.5%. Variation of chlorine content in each of the two coal seams shows that chlorine content increases with depth because the chloride in coal is in equilibrium with the chloride in the groundwater, which is also depth dependent. A low chlorine content in shallow regions of a coal seam is a result of leaching by fresh groundwater.

  6. The distribution and abundance of the freshwater mussels (Bivalvia: Unionacea) of the Navasota River, Texas

    E-Print Network [OSTI]

    Littleton, Thomas Glynn

    1979-01-01T23:59:59.000Z

    square miles (Anon. , 1950). The Navasota River drainage lies approximately on the boundary between the Austroriparian and Texan biotic provinces as defined by Blair (1950). It drains portions of the Blackland Prairie and Post Oak Savannah...THE DISTRIBUTION AND ABUNDANCE OF THE FRESHWATER MUSSELS (BIVALVIA: UNIONACEA) OF THE NAVASOTA RIVER, TEXAS A Thesis by THOMAS GLYNN LITTLETON Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement...

  7. Beryllium abundances in parent stars of extrasolar planets: 16 Cyg A & B and rho 1 Cnc

    E-Print Network [OSTI]

    R. J. Garcia Lopez; M. R. Perez de Taoro

    1998-03-03T23:59:59.000Z

    The Be II 3131 A doublet has been observed in the solar-type stars 16 Cyg A & B and in the late G-type star rho 1 Cnc, to derive their beryllium abundances. 16 Cyg A & B show similar (solar) beryllium abundances while 16 Cyg B, which has been proposed to have a planetary companion of ~2 M_Jup, is known to be depleted in lithium by a factor larger than 6 with respect to 16 Cyg A. Differences in their rotational histories which could induce different rates of internal mixing of material, and the ingestion of a similar planet by 16 Cyg A are discussed as potential explanations. The existence of two other solar-type stars which are candidates to harbour planetary-mass companions and which show lithium and beryllium abundances close to those of 16 Cyg A, requires a more detailed inspection of the peculiarities of the 16 Cyg system. For rho 1 Cnc, which is the coolest known object candidate to harbour a planetary-mass companion (M > 0.85 M_Jup), we establish a precise upper limit for its beryllium abundance, showing a strong Be depletion which constrains the available mixing mechanisms. Observations of similar stars without companions are required to asses the potential effects of the planetary companion on the observed depletion. It has been recently claimed that rho 1 Cnc appears to be a subgiant. If this were the case, the observed strong Li and Be depletions could be explained by a dilution process taking place during its post-main sequence evolution.

  8. Oxygen Abundances in Nearby Stars. Clues to the formation and evolution of the Galactic disk

    E-Print Network [OSTI]

    I. Ramirez; C. Allende Prieto; D. L. Lambert

    2007-01-12T23:59:59.000Z

    The abundances of iron and oxygen are homogeneously determined in a sample of 523 nearby (d-0.3, we find no obvious indication of a sudden decrease (i.e., a 'knee') in the [O/Fe] vs. [Fe/H] pattern of thick-disk stars that would connect the thick and thin disk trends at a high metallicity. We conclude that Type Ia supernovae (SN Ia) did not contribute significantly to the chemical enrichment of the thick disk. [Abridged

  9. Collisional excitation of hydrogen and the determination of the primordial helium abundance from H II regions

    E-Print Network [OSTI]

    G. Stasinska; Y. I. Izotov

    2001-09-17T23:59:59.000Z

    This paper investigates the effect of collisional enhancement of the hydrogen lines on the derivation of the helium abundances in low metallicity H II regions. For this, we have constructed a grid of photoionization models relevant for the analysis of giant \\hii regions in blue compact galaxies. We show that the effect of collisional excitation on the Halpha/Hbeta ratio can be quite important (up to 8% or more). The impact of this effect on the determination of the helium mass fraction has been tracked on four low-metallicity blue compact galaxies for which Keck spectra are available and which are among the best objects for the quest of the pregalactic helium abundance. We find that taking into account the effects of collisional excitation of hydrogen results in an upward correction of the helium mass fraction Y by up to 5%. However, combining with other systematic effects usually not considered in the determination of the helium abundance in low-metallicity galaxies, the resulting uncertainty should be much less.

  10. Abundance anomalies in metal-poor stars from Population III supernova ejecta hydrodynamics

    E-Print Network [OSTI]

    Sluder, Alan; Safranek-Shrader, Chalence; Milosavljevic, Milos; Bromm, Volker

    2015-01-01T23:59:59.000Z

    We present a simulation of the long-term evolution of a Population III supernova remnant in a cosmological minihalo. Employing passive Lagrangian tracer particles, we investigate how chemical stratification and anisotropy in the explosion can affect the abundances of the first low-mass, metal-enriched stars. We find that reverse shock heating can leave the inner mass shells at entropies too high to cool, leading to carbon-enhancement in the re-collapsing gas. This hydrodynamic selection effect could explain the observed incidence of carbon-enhanced metal-poor (CEMP) stars at low metallicity. We further explore how anisotropic ejecta distributions, recently seen in direct numerical simulations of core-collapse explosions, may translate to abundances in metal-poor stars. We find that some of the observed scatter in the Population II abundance ratios can be explained by an incomplete mixing of supernova ejecta, even in the case of only one contributing enrichment event. We demonstrate that the customary hypothes...

  11. Diversity of abundance patterns of neutron-capture elements in very metal-poor stars

    SciTech Connect (OSTI)

    Aoki, Misa; Ishimaru, Yuhri [International Christian University 10-2, Osawa, Mitaka, Tokyo 181-0015 (Japan); Aoki, Wako; Wanajo, Shinya [National Astronomical Observatory of Japan (NAOJ) 2-21-1, Osawa, Mitaka, Tokyo 181-8588 (Japan)

    2014-05-02T23:59:59.000Z

    Observations of Very Metal-Poor stars indicate that there are at least two sites to r-process; “weak r-process” and “main r-process”. A question is whether these two are well separated or there exists a variation in the r-process. We present the results of abundance analysis of neutron-capture elements in the two Very Metal-Poor stars HD107752 and HD110184 in the Milky Way halo observed with the Subaru Telescope HDS. The abundance patterns show overabundace at light n-capture elements (e.g. Sr, Y), inferring the element yielding of weak r-process, while heavy neutron-capture elements (e.g. Ba, Eu) are deficient; however, the overabundance of light ones is not as significant as that previously found in stars representing the weak r-process (e.g. HD122563; Honda et al. 2006). Our study show diversity in the abundance patterns from light to heavy neutron-capture elements in VMP stars, suggesting a variation in r-process, which may depend on electron fraction of environment.

  12. Solar Carbon Monoxide, Thermal Profiling, and the Abundances of C, O, and their Isotopes

    E-Print Network [OSTI]

    Thomas R. Ayres; Claude Plymate; Christoph U. Keller

    2006-06-07T23:59:59.000Z

    A solar photospheric "thermal profiling" analysis is presented, exploiting the infrared rovibrational bands of carbon monoxide (CO) as observed with the McMath-Pierce Fourier transform spectrometer (FTS) at Kitt Peak, and from above the Earth's atmosphere by the Shuttle-borne ATMOS experiment. Visible continuum intensities and center-limb behavior constrained the temperature profile of the deep photosphere, while CO center-limb behavior defined the thermal structure at higher altitudes. The oxygen abundance was self consistently determined from weak CO absorptions. Our analysis was meant to complement recent studies based on 3-D convection models which, among other things, have revised the historical solar oxygen (and carbon) abundance downward by a factor of nearly two; although in fact our conclusions do not support such a revision. Based on various considerations, an oxygen abundance of 700+/-100 ppm (parts per million relative to hydrogen) is recommended; the large uncertainty reflects the model sensitivity of CO. New solar isotopic ratios also are reported for 13C, 17O, and 18O.

  13. Water abundances in high-mass protostellar envelopes: Herschel observations with HIFI

    E-Print Network [OSTI]

    Marseille, M; Herpin, F; Wyrowski, F; Chavarria, L; Pietropaoli, B

    2015-01-01T23:59:59.000Z

    We derive the dense core structure and the water abundance in four massive star-forming regions which may help understand the earliest stages of massive star formation. We present Herschel-HIFI observations of the para-H2O 1_11-0_00 and 2_02-1_11 and the para-H2-18O 1_11-0_00 transitions. The envelope contribution to the line profiles is separated from contributions by outflows and foreground clouds. The envelope contribution is modelled using Monte-Carlo radiative transfer codes for dust and molecular lines (MC3D and RATRAN), with the water abundance and the turbulent velocity width as free parameters. While the outflows are mostly seen in emission in high-J lines, envelopes are seen in absorption in ground-state lines, which are almost saturated. The derived water abundances range from 5E-10 to 4E-8 in the outer envelopes. We detect cold clouds surrounding the protostar envelope, thanks to the very high quality of the Herschel-HIFI data and the unique ability of water to probe them. Several foreground cloud...

  14. The Abundance Distribution in the Extrasolar-Planet Host Star HD19994

    E-Print Network [OSTI]

    Verne V. Smith; Katia Cunha; Daniela Lazzaro

    2001-03-04T23:59:59.000Z

    Abundances of 22 elements have been determined from a high-resolution, high signal-to-noise spectrum of HD19994, a star recently announced as harboring an extrasolar planet. A detailed spectroscopic analysis of this stars finds it to have a mass of 1.2+/-0.1Msun. HD19994 is found to be slightly enriched in "metals" relative to the Sun 9[Fe/H]=+0.09+/-0.05 and an average of all metals of [m/H]=+0.13), as are most stars known with extrasolar planets. In a search for possible signatures of accretion of metal-rich gas onto the parent stars (using HD19994 and published abundances for other stars), it is found that a small subset of stars with planets exhibit a trend of increasing [X/H] with increasing condensation temperature for a given element X. This trend may point to the accretion of chemically fractionated solid material into the outer (thin) convection zones of these solar-type stars. It is also found that this small group of stars exhibiting an accretion signature all have large planets orbiting much closer than is found, in general, for stars with planets not showing this peculiar abundance trend, suggesting a physical link between accretion and orbital separation. In addition, the stars showing evidence of fractionated accretion are, on average, of larger mass (1.2Msun) than stars not showing measurable evidence of accretion (1.0Msun).

  15. Constraining the abundances of complex organics in the inner regions of solar-type protostars

    E-Print Network [OSTI]

    Taquet, Vianney; Ceccarelli, Cecilia; Neri, Roberto; Kahane, Claudine; Charnley, Steven B

    2015-01-01T23:59:59.000Z

    The high abundances of Complex Organic Molecules (COMs) with respect to methanol, the most abundant COM, detected towards low-mass protostars, tend to be underpredicted by astrochemical models. This discrepancy might come from the large beam of the single-dish telescopes, encompassing several components of the studied protostar, commonly used to detect COMs. To address this issue, we have carried out multi-line observations of methanol and several COMs towards the two low-mass protostars NGC1333-IRAS2A and -IRAS4A with the Plateau de Bure interferometer at an angular resolution of 2 arcsec, resulting in the first multi-line detection of the O-bearing species glycolaldehyde and ethanol and of the N-bearing species ethyl cyanide towards low-mass protostars other than IRAS 16293. The high number of detected transitions from COMs (more than 40 methanol transitions for instance) allowed us to accurately derive the source size of their emission and the COMs column densities. The COMs abundances with respect to meth...

  16. A Comparison of Copper Abundances in Globular Cluster and Halo Field Giant Stars

    E-Print Network [OSTI]

    Jennifer Simmerer; Christopher Sneden; Inese I. Ivans; Robert P. Kraft; Matthew D. Shetrone; Verne V. Smith

    2003-03-07T23:59:59.000Z

    We derive [Cu/Fe] for 117 giant stars in ten globular clusters (M3, M4, M5, M10, M13, M15, M71, NGC 7006, NCG 288, and NGC 362) and find that globular cluster Cu abundances appear to follow [Cu/Fe] trends found in the field. This result is interesting in light of recent work which indicates that the globular cluster Omega Centauri shows no trend in [Cu/Fe] with [Fe/H] over the abundance range -2.0 <[Fe/H]< -0.8. Of particular interest are the two clusters M4 and M5. While at a similar metallicity ([Fe/H] ~- 1.2), they differ greatly in some elemental abundances: M4 is largely overabundant in Si, Ba, and La compared to M5. We find that it is also overabundant in Cu with respect to M5, though this overabundance is in accord with [Cu/Fe] ratios found in the field.

  17. Sodium and Oxygen Abundances in the Open Cluster NGC 6791 from APOGEE H-Band Spectroscopy

    E-Print Network [OSTI]

    Cunha, Katia; Johnson, Jennifer A; Bergemann, Maria; Meszaros, Szabolcs; Shetrone, Matthew D; Souto, Diogo; Prieto, Carlos Allende; Schiavon, Ricardo P; Frinchaboy, Peter; Zasowski, Gail; Bizyaev, Dmitry; Holtzman, Jon; Perez, Ana E Garcia; Majewski, Steven R; Nidever, David; Beers, Timothy; Carrera, Ricardo; Geisler, Doug; Gunn, James; Hearty, Fred; Ivans, Inese; Martell, Sarah; Pinsonneault, Marc; Schneider, Donald P; Sobeck, Jennifer; Stello, Dennis; Stassun, Keivan G; Skrutskie, Michael; Wilson, John C

    2014-01-01T23:59:59.000Z

    The open cluster NGC 6791 is among the oldest, most massive and metal-rich open clusters in the Galaxy. High-resolution $H$-band spectra from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) of 11 red giants in NGC 6791 are analyzed for their chemical abundances of iron, oxygen, and sodium. The abundances of these three elements are found to be homogeneous (with abundance dispersions at the level of $\\sim$ 0.05 - 0.07 dex) in these cluster red giants, which span much of the red-giant branch (T$_{\\rm eff}$ $\\sim$ 3500K - 4600K), and include two red-clump giants. From the infrared spectra, this cluster is confirmed to be among the most metal-rich clusters in the Galaxy ($$ = 0.34 $\\pm$ 0.06), and is found to have a roughly solar value of [O/Fe] and slightly enhanced [Na/Fe]. Non-LTE calculations for the studied Na I lines in the APOGEE spectral region ($\\lambda$16373.86\\AA\\ and $\\lambda$16388.85\\AA) indicate only small departures from LTE ($\\leq$ 0.04 dex) for the parameter range and metallic...

  18. Chemical Feature of Eu abundance in the Draco dwarf spheroidal galaxy

    E-Print Network [OSTI]

    Tsujimoto, Takuji; Shigeyama, Toshikazu; Aoki, Wako

    2015-01-01T23:59:59.000Z

    Chemical abundance of r-process elements in nearby dwarf spheroidal (dSph) galaxies is a powerful tool to probe the site of r-process since their small-mass scale can sort out individual events producing r-process elements. A merger of binary neutron stars is a promising candidate of this site. In faint, or less massive dSph galaxies such as the Draco, a few binary neutron star mergers are expected to have occurred at most over the whole past. We have measured chemical abundances including Eu and Ba of three red giants in the Draco dSph by Subaru/HDS observation. The Eu detection for one star with [Fe/H]=-1.45 confirms a broadly constant [Eu/H] of ~-1.3 for stars with [Fe/H]>-2. This feature is shared by other dSphs with similar masses, i.e., the Sculptor and the Carina, and suggests that neutron star merger is the origin of r-process elements in terms of its rarity. In addition, two very metal-poor stars with [Fe/H]=-2.12 and -2.51 are found to exhibit very low Eu abundances such as [Eu/H]<-2 with an impl...

  19. Chemical Abundances of the Highly Obscured Galactic Globular Clusters 2MASS GC02 and Mercer 5

    E-Print Network [OSTI]

    Penaloza, Francisco; Vasquez, Sergio; Borissova, Jura; Kurtev, Radostin; Zoccali, Manuela

    2015-01-01T23:59:59.000Z

    We present the first high spectral resolution abundance analysis of two newly discovered Galactic globular clusters, namely Mercer 5 and 2MASS GC02 residing in regions of high interstellar reddening in the direction of the Galactic center. The data were acquired with the Phoenix high-resolution near-infrared echelle spectrograph at Gemini South (R~50000) in the 15500.0 A - 15575.0 A spectral region. Iron, Oxygen, Silicon, Titanium and Nickel abundances were derived for two red giant stars, in each cluster, by comparing the entire observed spectrum with a grid of synthetic spectra generated with MOOG. We found [Fe/H] values of -0.86 +/- 0.12 and -1.08 +/- 0.13 for Mercer 5 and 2MASS GC02 respectively. The [O/Fe], [Si/Fe] and [Ti/Fe] ratios of the measured stars of Mercer 5 follow the general trend of both bulge field and cluster stars at this metallicity, and are enhanced by > +0.3. The 2MASS GC02 stars have relatively lower ratios, but still compatible with other bulge clusters. Based on metallicity and abund...

  20. Solar Flare Element Abundances from the Solar Assembly for X-rays (SAX) on MESSENGER

    E-Print Network [OSTI]

    Dennis, B R; Schwartz, R A; Tolbert, A K; Starr, R D; Nittler, L R

    2015-01-01T23:59:59.000Z

    X-ray spectra in the range $1.5-8.5$~keV have been analyzed for 526 large flares detected with the Solar Assembly for X-rays (SAX) on the Mercury {\\em MESSENGER} spacecraft between 2007 and 2013. For each flare, the temperature and emission measure of the emitting plasma were determined from the spectrum of the continuum. In addition, with the SAX energy resolution of 0.6 keV (FWHM) at 6~keV, the intensities of the clearly resolved Fe-line complex at 6.7~keV and the Ca-line complex at 3.9~keV were determined, along with those of unresolved line complexes from S, Si, and Ar at lower energies. Comparisons of these line intensities with theoretical spectra allow the abundances of these elements relative to hydrogen to be derived, with uncertainties due to instrument calibration and the unknown temperature distribution of the emitting plasma. While significant deviations are found for the abundances of Fe and Ca from flare to flare, the abundances averaged over all flares are found to be enhanced over photospheri...

  1. Origin of the heavy elements in HD 140283. Measurement of europium abundance

    E-Print Network [OSTI]

    Mello, C Siqueira; Spite, M; Spite, F

    2012-01-01T23:59:59.000Z

    HD 140283 is a nearby (V=7.7) subgiant metal-poor star, extensively analysed in the literature. Although many spectra have been obtained for this star, none showed a signal-to-noise (S/N) ratio high enough to enable a very accurate derivation of abundances from weak lines. The detection of europium proves that the neutron-capture elements in this star originate in the r-process, and not in the s-process, as recently claimed in the literature. Based on the OSMARCS 1D LTE atmospheric model and with a consistent approach based on the spectrum synthesis code Turbospectrum, we measured the europium lines at 4129 {\\AA} and 4205 {\\AA}, taking into account the hyperfine structure of the transitions. The spectrum, obtained with a long exposure time of seven hours at the Canada-France-Hawaii Telescope (CFHT), has a resolving power of 81000 and a S/N ratio of 800 at 4100 {\\AA}. We were able to determine the abundance A(Eu)=-2.35 dex, compatible with the value predicted for the europium from the r-process. The abundance ...

  2. Abundance gradients in the Milky Way for alpha elements, Iron peak elements, Barium, Lanthanum and Europium

    E-Print Network [OSTI]

    Cescutti, G; François, P; Chiappini, C

    2006-01-01T23:59:59.000Z

    We model the abundance gradients in the disk of the Milky Way for several chemical elements (O, Mg, Si, S, Ca, Sc, Ti, Co, V, Fe, Ni, Zn, Cu, Mn, Cr, Ba, La and Eu), and compare our results with the most recent and homogeneous observational data. We adopt a chemical evolution model able to well reproduce the main properties of the solar vicinity. We compute, for the first time, the abundance gradients for all the above mentioned elements in the galactocentric distance range 4 - 22 kpc. The comparison with the observed data on Cepheids in the galactocentric distance range 5-17 kpc gives a very good agreement for many of the studied elements. In addition, we fit very well the data for the evolution of Lanthanum in the solar vicinity for which we present results here for the first time. We explore, also for the first time, the behaviour of the abundance gradients at large galactocentric distances by comparing our results with data relative to distant open clusters and red giants and select the best chemical evol...

  3. NATURAL RESOURCES ASSESSMENT

    SciTech Connect (OSTI)

    D.F. Fenster

    2000-12-11T23:59:59.000Z

    The purpose of this report is to summarize the scientific work that was performed to evaluate and assess the occurrence and economic potential of natural resources within the geologic setting of the Yucca Mountain area. The extent of the regional areas of investigation for each commodity differs and those areas are described in more detail in the major subsections of this report. Natural resource assessments have focused on an area defined as the ''conceptual controlled area'' because of the requirements contained in the U.S. Nuclear Regulatory Commission Regulation, 10 CFR Part 60, to define long-term boundaries for potential radionuclide releases. New requirements (proposed 10 CFR Part 63 [Dyer 1999]) have obviated the need for defining such an area. However, for the purposes of this report, the area being discussed, in most cases, is the previously defined ''conceptual controlled area'', now renamed the ''natural resources site study area'' for this report (shown on Figure 1). Resource potential can be difficult to assess because it is dependent upon many factors, including economics (demand, supply, cost), the potential discovery of new uses for resources, or the potential discovery of synthetics to replace natural resource use. The evaluations summarized are based on present-day use and economic potential of the resources. The objective of this report is to summarize the existing reports and information for the Yucca Mountain area on: (1) Metallic mineral and mined energy resources (such as gold, silver, etc., including uranium); (2) Industrial rocks and minerals (such as sand, gravel, building stone, etc.); (3) Hydrocarbons (including oil, natural gas, tar sands, oil shales, and coal); and (4) Geothermal resources. Groundwater is present at the Yucca Mountain site at depths ranging from 500 to 750 m (about 1,600 to 2,500 ft) below the ground surface. Groundwater resources are not discussed in this report, but are planned to be included in the hydrology section of future revisions of the ''Yucca Mountain Site Description'' (CRWMS M&O 2000c).

  4. Artificial nature : water infrastructure and its experience as natural space

    E-Print Network [OSTI]

    Demirta?, Fatma Asl?han, 1970-

    2000-01-01T23:59:59.000Z

    This work is about water infrastructure and its experience as urban and natural space. It deals with the concepts of nature/geography, technology, and the integral experiential space by analyzing water dams and reservoirs ...

  5. Natural gas monthly, April 1999

    SciTech Connect (OSTI)

    NONE

    1999-05-06T23:59:59.000Z

    The Natural Gas Monthly (NGM) highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information. There are two feature articles in this issue: Natural gas 1998: Issues and trends, Executive summary; and Special report: Natural gas 1998: A preliminary summary. 6 figs., 28 tabs.

  6. Exploring mass loss, low-Z accretion, and convective overshoot in solar models to mitigate the solar abundance problem

    E-Print Network [OSTI]

    Guzik, Joyce Ann

    2010-01-01T23:59:59.000Z

    Solar models using the new lower abundances of Asplund et al. (2005) or Asplund et al. (2009) do not agree as well with helioseismic inferences as models that use the higher Grevesse & Noels (1993) or Grevesse & Sauval (1998) abundances. Adopting the new abundances leads to models with sound speed discrepancies of up to 1.4% below the base of the convection zone (compared to discrepancies of less than 0.4% with the old abundances), a convection zone that is too shallow, and a convection zone helium abundance that is too low. Here we review breifly previous attempts to restore agreement, and we evaluate three suggested changes to the models: early mass loss, accretion of low-Z material, and convective overshoot. One goal of these attempts is to explore models that could preserve the structure in the interior obtained with the old abundances while accomodating the new abundances at the surface. Although the mass-losing and accretion models show some improvement in agreement with seismic constraints, a s...

  7. Are oxygen and neon enriched in PNe and is the current solar Ne/O abundance ratio underestimated?

    E-Print Network [OSTI]

    W. Wang; X. -W. Liu

    2008-06-13T23:59:59.000Z

    A thorough critical literature survey has been carried out for reliable measurements of oxygen and neon abundances of planetary nebulae (PNe) and HII regions. By contrasting the results of PNe and of HII regions, we aim to address the issues of the evolution of oxygen and neon in the interstellar medium (ISM) and in the late evolutionary phases of low- and intermediate-mass stars (LIMS), as well as the currently hotly disputed solar Ne/O abundance ratio. Through the comparisons, we find that neon abundance and Ne/O ratio increase with increasing oxygen abundance in both types of nebulae, with positive correlation coefficients larger than 0.75. The correlations suggest different enrichment mechanisms for oxygen and neon in the ISM, in the sense that the growth of neon is delayed compared to oxygen. The differences of abundances between PNe and HII regions, are mainly attributed to the results of nucleosynthesis and dredge-up processes that occurred in the progenitor stars of PNe. We find that both these alpha-elements are significantly enriched at low metallicity (initial oxygen abundance oxygen in intermediate mass stars (IMS) of low initial metallicities and in more massive stars, a conjecture that requires verification by further theoretical studies. This result also strongly suggests that both the solar neon abundance and the Ne/O ratio should be revised upwards by ~0.22 dex from the Asplund, Grevesse & Sauval values or by ~0.14 dex from the Grevesse & Sauval values.

  8. ELEMENTAL ABUNDANCES IN THE X-RAY GAS OF EARLY-TYPE GALAXIES WITH XMM-NEWTON AND CHANDRA OBSERVATIONS

    SciTech Connect (OSTI)

    Ji Jun; Irwin, Jimmy A.; Athey, Alex; Bregman, Joel N.; Lloyd-Davies, Edward J. [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States)], E-mail: jijun@umich.edu, E-mail: jairwin@umich.edu, E-mail: athey@arlut.utexas.edu, E-mail: jbregman@umich.edu, E-mail: radix@freeshell.org

    2009-05-10T23:59:59.000Z

    The source of hot gas in elliptical galaxies is thought to be due to stellar mass loss, with contributions from supernova (SN) events and possibly from infall from a surrounding environment. This picture predicts supersolar values for the metallicity of the gas toward the inner part of the galaxy, which can be tested by measuring the gas phase abundances. We use high-quality data for 10 nearby early-type galaxy from XMM-Newton, featuring both the European Photon Imaging Camera and the Reflection Grating Spectrometer, where the strongest emission lines are detected with little blending; some Chandra data are also used. We find excellent consistency in the elemental abundances between the different XMM-Newton instruments and good consistency with Chandra. Differences in abundances with aperture size and model complexity are examined, but large differences rarely occur. For a two-temperature thermal model plus a point source contribution, the median Fe and O abundances are 0.86 and 0.44 of the solar value, while Si and Mg abundances are similar to that for Fe. This is similar to stellar abundances for these galaxies but SNe were expected to enhance the gas phase abundances considerably, which is not observed.

  9. The solar photospheric abundance of hafnium and thorium. Results from CO5BOLD 3D hydrodynamic model atmospheres

    E-Print Network [OSTI]

    Elisabetta Caffau; L. Sbordone; H. -G. Ludwig; P. Bonifacio; M. Steffen; N. T. Behara

    2008-03-25T23:59:59.000Z

    Context: The stable element hafnium (Hf) and the radioactive element thorium (Th) were recently suggested as a suitable pair for radioactive dating of stars. The applicability of this elemental pair needs to be established for stellar spectroscopy. Aims: We aim at a spectroscopic determination of the abundance of Hf and Th in the solar photosphere based on a \\cobold 3D hydrodynamical model atmosphere. We put this into a wider context by investigating 3D abundance corrections for a set of G- and F-type dwarfs. Method: High-resolution, high signal-to-noise solar spectra were compared to line synthesis calculations performed on a solar CO5BOLD model. For the other atmospheres, we compared synthetic spectra of CO5BOLD 3D and associated 1D models. Results: For Hf we find a photospheric abundance A(Hf)=0.87+-0.04, in good agreement with a previous analysis, based on 1D model atmospheres. The weak Th ii 401.9 nm line constitutes the only Th abundance indicator available in the solar spectrum. It lies in the red wing of an Ni-Fe blend exhibiting a non-negligible convective asymmetry. Accounting for the asymmetry-related additional absorption, we obtain A(Th)=0.09+-0.03, consistent with the meteoritic abundance, and about 0.1 dex lower than obtained in previous photospheric abundance determinations. Conclusions: Only for the second time, to our knowledge, has am non-negligible effect of convective line asymmetries on an abundance derivation been highlighted. Three-dimensional hydrodynamical simulations should be employed to measure Th abundances in dwarfs if similar blending is present, as in the solar case. In contrast, 3D effects on Hf abundances are small in G- to mid F-type dwarfs and sub-giants, and 1D model atmospheres can be conveniently used.

  10. EIA - Natural Gas Publications

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742 33 111 1,613 122 40CoalLease(Billion2,128 2,469DecadeOrigin State Glossary HomeCapacityNatural Gas

  11. Natural Gas Transportation Resiliency

    Energy Savers [EERE]

    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: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are being directed offOCHCO2:Introduction toManagement ofConverDyn NOPRNancyNationalNatural GasImports byTransportation

  12. Sandia Energy - Natural Gas

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOnItemResearch > TheNuclear PressLaboratory Fellows Jerry SimmonsModels &Natural

  13. Natural Gas Processed

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742 33 111 1,613 122 40 Buildingto17 3400,Information Administration22)May£661.DataNov-14LiquidsNatural

  14. Natural gas monthly, December 1995

    SciTech Connect (OSTI)

    NONE

    1995-12-01T23:59:59.000Z

    This report presents information of interest to organizations associated with the natural gas industry. Data are presented on natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also included.

  15. Natural Gas Exports from Iran

    Reports and Publications (EIA)

    2012-01-01T23:59:59.000Z

    This assessment of the natural gas sector in Iran, with a focus on Iran’s natural gas exports, was prepared pursuant to section 505 (a) of the Iran Threat Reduction and Syria Human Rights Act of 2012 (Public Law No: 112-158). As requested, it includes: (1) an assessment of exports of natural gas from Iran; (2) an identification of the countries that purchase the most natural gas from Iran; (3) an assessment of alternative supplies of natural gas available to those countries; (4) an assessment of the impact a reduction in exports of natural gas from Iran would have on global natural gas supplies and the price of natural gas, especially in countries identified under number (2); and (5) such other information as the Administrator considers appropriate.

  16. Natural gas monthly, May 1999

    SciTech Connect (OSTI)

    NONE

    1999-05-01T23:59:59.000Z

    The Natural Gas Monthly (NGM) highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time the NGM features articles designed to assist readers in using and interpreting natural gas information. 6 figs., 27 tabs.

  17. Natural gas monthly, July 1996

    SciTech Connect (OSTI)

    NONE

    1996-07-01T23:59:59.000Z

    This document presents information pertaining to the natural gas industry. Data are included on production, consumption, distribution, and pipeline activities.

  18. Natural gas monthly, August 1994

    SciTech Connect (OSTI)

    Not Available

    1994-08-24T23:59:59.000Z

    The Natural Gas Monthly (NGM) highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information.

  19. Natural gas monthly, October 1998

    SciTech Connect (OSTI)

    NONE

    1998-10-01T23:59:59.000Z

    The Natural Gas Monthly (NGM) highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information. 6 figs., 27 tabs.

  20. Natural gas monthly, June 1999

    SciTech Connect (OSTI)

    NONE

    1999-06-01T23:59:59.000Z

    The Natural Gas Monthly (NGM) highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information. 6 figs., 25 tabs.

  1. Natural gas monthly: December 1993

    SciTech Connect (OSTI)

    Not Available

    1993-12-01T23:59:59.000Z

    The Natural Gas Monthly (NGM) highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. Articles are included which are designed to assist readers in using and interpreting natural gas information.

  2. Natural gas monthly, June 1993

    SciTech Connect (OSTI)

    Not Available

    1993-06-22T23:59:59.000Z

    The Natural Gas Monthly (NGM) highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information.

  3. Natural gas monthly, July 1993

    SciTech Connect (OSTI)

    Not Available

    1993-07-27T23:59:59.000Z

    The Natural Gas Monthly NGM highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information.

  4. Natural gas monthly, November 1993

    SciTech Connect (OSTI)

    Not Available

    1993-11-29T23:59:59.000Z

    The Natural Gas Monthly (NGM) highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground state data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information.

  5. Natural Resource Management Plan Update

    E-Print Network [OSTI]

    Homes, Christopher C.

    wood industry, some farming in area of Solar Farm 3 #12;History of Natural Resource Management Formal

  6. Natural gas monthly, July 1998

    SciTech Connect (OSTI)

    NONE

    1998-07-01T23:59:59.000Z

    The Natural Gas Monthly (NGM) highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information. 6 figs., 25 tabs.

  7. Natural gas monthly, April 1995

    SciTech Connect (OSTI)

    NONE

    1995-04-27T23:59:59.000Z

    The Natural Gas Monthly highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information. 6 figs., 31 tabs.

  8. Natural Gas Monthly, March 1996

    SciTech Connect (OSTI)

    NONE

    1996-03-25T23:59:59.000Z

    The Natural Gas Monthly (NGM) highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information.

  9. Natural gas monthly, June 1998

    SciTech Connect (OSTI)

    NONE

    1998-06-01T23:59:59.000Z

    The Natural Gas Monthly (NGM) highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information. 6 figs., 27 tabs.

  10. warnell school Forestry & Natural Resources

    E-Print Network [OSTI]

    Hall, Daniel

    warnell school Forestry & Natural Resources 2010 Annual Report o #12;VisionTo be recognized as one of the top five forestry and natural resource programs in the United States. MissionTo prepare resources; and to place latest ideas and technology in forestry and natural resource management into real

  11. wind engineering & natural disaster mitigation

    E-Print Network [OSTI]

    Denham, Graham

    wind engineering & natural disaster mitigation #12;wind engineering & natural disaster mitigation Investment WindEEE Dome at Advanced Manufacturing Park $31million Insurance Research Lab for Better Homes $8million Advanced Facility for Avian Research $9million #12;wind engineering & natural disaster mitigation

  12. Natural gas monthly, January 1999

    SciTech Connect (OSTI)

    NONE

    1999-02-01T23:59:59.000Z

    The Natural Gas Monthly (NGM) highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. 6 figs., 28 tabs.

  13. Natural gas monthly, November 1998

    SciTech Connect (OSTI)

    NONE

    1998-11-01T23:59:59.000Z

    The Natural Gas Monthly (NGM) highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. 6 figs., 27 tabs.

  14. Natural gas monthly, February 1999

    SciTech Connect (OSTI)

    NONE

    1999-02-01T23:59:59.000Z

    The Natural Gas Monthly (NGM) highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. 6 figs., 28 tabs.

  15. NATIONAL MUSEUM OF NATURAL HISTORY

    E-Print Network [OSTI]

    Mathis, Wayne N.

    NATIONAL MUSEUM OF NATURAL HISTORY Annual Report 2004 #12;2 NATIONAL MUSEUM OF NATURAL HISTORY · www.mnh.si.edu The revitalization of the National Museum of Natural History proceeded at a rapid pace, innovation and solid groundwork for future growth. The Museum's agenda is an active one. As with any

  16. Field Museum of Natural History

    E-Print Network [OSTI]

    Patterson, Bruce D.

    Field Museum of Natural History Financial Statements as of and for the Years Ended December 31' Report #12;FIELD MUSEUM OF NATURAL HISTORY TABLE OF CONTENTS Page INDEPENDENT AUDITORS' REPORT 1 AUDITORS' REPORT To the Board of Trustees of Field Museum of Natural History: We have audited

  17. Field Museum of Natural History

    E-Print Network [OSTI]

    Patterson, Bruce D.

    Field Museum of Natural History Financial Statements as of and for the Years Ended December 31 Auditors' Report #12;FIELD MUSEUM OF NATURAL HISTORY TABLE OF CONTENTS Page INDEPENDENT AUDITORS' REPORT 1 Expenditures 22­23 #12;INDEPENDENT AUDITORS' REPORT To the Board of Trustees of Field Museum of Natural History

  18. Europium Isotopic Abundances in Very Metalpoor Stars 1 Christopher Sneden 2 , John J. Cowan 3 , James E. Lawler 4 , Scott Burles 5 , Timothy C.

    E-Print Network [OSTI]

    Cowan, John

    Europium Isotopic Abundances in Very Metal­poor Stars 1 Christopher Sneden 2 , John J. Cowan 3, La Jolla, CA 92093­0319; gfuller@ucsd.edu #12; -- 2 -- ABSTRACT Europium isotopic abundance fractions

  19. Upper limits for the existence of long-lived isotopes of roentgenium in natural gold

    SciTech Connect (OSTI)

    Dellinger, F.; Kutschera, W.; Forstner, O.; Golser, R.; Priller, A.; Steier, P.; Wallner, A.; Winkler, G. [University of Vienna, Faculty of Physics, Vienna Environmental Research Accelerator (VERA) Laboratory, Waehringer Strasse 17, A-1090 Wien (Austria)

    2011-01-15T23:59:59.000Z

    A sensitive search for isotopes of a superheavy element (SHE) in natural gold materials has been performed with accelerator mass spectrometry at the Vienna Environmental Research Accelerator, which is based on a 3-MV tandem accelerator. Because the most likely SHE in gold is roentgenium (Rg, Z = 111), the search concentrated on Rg isotopes. Two different mass regions were explored: (i) For the neutron-deficient isotopes {sup 261}Rg and {sup 265}Rg, abundance limits in gold of 3x10{sup -16} were reached (no events observed). This is in stark contrast to the findings of Marinov et al.[Int. J. Mod. Phys. E 18, 621 (2009)], who reported positive identification of these isotopes with inductively coupled plasma sector field mass spectrometry in the (1-10)x10{sup -10} abundance range. (ii) Theoretical models of SHEs predict a region of increased stability around the proton and neutron shell closures of Z = 114 and N = 184. We therefore investigated eight heavy Rg isotopes, {sup A}Rg, A = 289, 290, 291, 292, 293, 294, 295, and 296. For six isotopes no events were observed, setting limits also in the 10{sup -16} abundance range. For {sup 291}Rg and {sup 294}Rg we observed two and nine events, respectively, which results in an abundance in the 10{sup -15} range. However, pileup of a particularly strong background in these cases makes a positive identification as Rg isotopes--even after pileup correction--unlikely.

  20. Natural gas monthly, October 1997

    SciTech Connect (OSTI)

    NONE

    1997-10-01T23:59:59.000Z

    The Natural Gas Monthly highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information. The feature article in this issue is a special report, ``Comparison of Natural Gas Storage Estimates from the EIA and AGA.`` 6 figs., 26 tabs.

  1. Natural gas monthly, June 1996

    SciTech Connect (OSTI)

    NONE

    1996-06-24T23:59:59.000Z

    The natural gas monthly (NGM) highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information. The feature article for this month is Natural Gas Industry Restructuring and EIA Data Collection.

  2. Natural gas monthly, October 1996

    SciTech Connect (OSTI)

    NONE

    1996-10-01T23:59:59.000Z

    The Natural Gas Monthly (NGM) is prepared in the Data Operations Branch of the Reserves and Natural Gas Division, Office of Oil and Gas, Energy Information Administration (EIA), U.S. Department of Energy (DOE). The NGM highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information.

  3. Natural gas monthly, April 1997

    SciTech Connect (OSTI)

    NONE

    1997-04-01T23:59:59.000Z

    The Natural Gas Monthly (NGM) highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are present3ed each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information. The feature article is entitled ``Natural gas pipeline and system expansions.`` 6 figs., 27 tabs.

  4. Natural gas monthly, May 1997

    SciTech Connect (OSTI)

    NONE

    1997-05-01T23:59:59.000Z

    The Natural Gas Monthly highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information. The feature article this month is ``Restructuring energy industries: Lessons from natural gas.`` 6 figs., 26 tabs.

  5. Natural gas monthly, March 1994

    SciTech Connect (OSTI)

    Not Available

    1994-03-22T23:59:59.000Z

    The Natural Gas Monthly (NGM) is prepared in the Data Operations Branch of the Reserves and Natural Gas Division, Office of Oil and Gas, Energy Information Administration (EIA), US Department of energy (DOE). The NGM highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information.

  6. Natural gas monthly, August 1993

    SciTech Connect (OSTI)

    Not Available

    1993-08-25T23:59:59.000Z

    The Natural Gas Monthly (NGM) is prepared in the Data Operations Branch of the Reserves and Natural Gas Division, Office of Oil and Gas, Energy Information Administration (EIA), US Department of Energy (DOE). The NGM highhghts activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information.

  7. Natural Gas Monthly, October 1993

    SciTech Connect (OSTI)

    Not Available

    1993-11-10T23:59:59.000Z

    The (NGM) Natural Gas Monthly highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information. This month`s feature articles are: US Production of Natural Gas from Tight Reservoirs: and Expanding Rule of Underground Storage.

  8. Natural gas monthly, September 1993

    SciTech Connect (OSTI)

    Not Available

    1993-09-27T23:59:59.000Z

    The Natural Gas Monthly (NGM) is prepared in the Data Operations Branch of the Reserves and Natural Gas Division, Office of Oil and Gas, Energy Information Administration (EIA), US Department of Energy (DOE). The NGM highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information.

  9. Natural gas monthly, July 1997

    SciTech Connect (OSTI)

    NONE

    1997-07-01T23:59:59.000Z

    The Natural Gas Monthly (NGM) highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information. The feature article this month is entitled ``Intricate puzzle of oil and gas reserves growth.`` A special report is included on revisions to monthly natural gas data. 6 figs., 24 tabs.

  10. Natural gas monthly, December 1997

    SciTech Connect (OSTI)

    NONE

    1997-12-01T23:59:59.000Z

    The Natural Gas Monthly highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information. The article this month is entitled ``Recent Trends in Natural Gas Spot Prices.`` 6 figs., 27 tabs.

  11. Heat distribution by natural convection

    SciTech Connect (OSTI)

    Balcomb, J.D.

    1985-01-01T23:59:59.000Z

    Natural convection can provide adequate heat distribution in many situtations that arise in buildings. This is appropriate, for example, in passive solar buildings where some rooms tend to be more strongly solar heated than others or to reduce the number of heating units required in a building. Natural airflow and heat transport through doorways and other internal building apertures is predictable and can be accounted for in the design. The nature of natural convection is described, and a design chart is presented appropriate to a simple, single-doorway situation. Natural convective loops that can occur in buildings are described and a few design guidelines are presented.

  12. Nature Macmillan Publishers Ltd 1998 10. Gregorich, E. G., Ellert, B. H., Drury, C. F. & Liang, B. C. Fertilization effects on soil organic matter

    E-Print Network [OSTI]

    Casanova, Christian

    Analysis Center, Oak Ridge National Laboratory, TN, 1997). 21. Chou, T. H. Energy and Economic Analyses and transfer in vetch and vetch-oats mixtures. Soil biol. Biochem. 23, 447±452 (1991). 26. Paul, E. A. & Clark on the manuscript; J. Duxbury for discussions of 13 C natural abundance methodology; and E. A. Paul for funding

  13. letters to nature 152 NATURE |VOL 415 |10 JANUARY 2002 |www.nature.com

    E-Print Network [OSTI]

    Jacobson, Joseph

    . Recent developments in magnetic refrigeration. Mater. Sci. Forum 315± 317, 69±76 (1999). 4. Zimm, C. et al. Description and performance of a near-room temperature magnetic refrigerator. Adv. Cryogen. Engletters to nature 152 NATURE |VOL 415 |10 JANUARY 2002 |www.nature.com magnetization process can

  14. letters to nature NATURE |VOL 404 |2 MARCH 2000 |www.nature.com 69

    E-Print Network [OSTI]

    Larson, Kristine

    and the effects nonprecipitating clouds have on aerosol size distribution. J. Geophys. Res. 99, 14443±14459 (1994 determining their size distribution. J. Geophys. Res. 102, 21315±21328 (1997). 8. Hoppel, W. A., Frick, G. Mletters to nature NATURE |VOL 404 |2 MARCH 2000 |www.nature.com 69 subsequent self-coagulation

  15. The effect of cattle grazing on the abundance and distribution of selected macroinvertebrates in west Galveston Island salt marshes

    E-Print Network [OSTI]

    Martin, Jennifer Lynn

    2004-09-30T23:59:59.000Z

    The effect of cattle grazing on the abundance and distribution of vegetation, burrowing crabs (Uca rapax, Uca pugnax, and Sesarma cinereum), marsh periwinkles (Littoraria irrorata), horn snails (Cerithidea pliculosa), and salt marsh snails (Melampus...

  16. Influence of hydrological seasonality on sandbank benthos: algal biomass and shrimp abundance in a large neotropical river

    E-Print Network [OSTI]

    Montoya Ceballos, Jose Vicente

    2009-05-15T23:59:59.000Z

    In this study, I examined the influence of hydrological seasonality on spatiotemporal variation of algal biomass and shrimp abundance on sandbanks of the Cinaruco River in southwestern Venezuela. Seasonal variations of abiotic and biotic variables...

  17. ORIGIN OF THE UNUSUALLY LOW NITROGEN ABUNDANCES IN YOUNG POPULATIONS OF THE LARGE MAGELLANIC CLOUD

    SciTech Connect (OSTI)

    Bekki, Kenji [ICRAR, M468, University of Western Australia, 35 Stirling Highway, Crawley Western Australia 6009 (Australia); Tsujimoto, Takuji [National Astronomical Observatory, Mitaka-shi, Tokyo 181-8588 (Japan)

    2010-10-01T23:59:59.000Z

    It is a longstanding problem that H II regions and very young stellar populations in the Large Magellanic Cloud (LMC) have nitrogen abundances ([N/H]) that are a factor of {approx}7 lower than the solar value. We here discuss a new scenario in which the observed unusually low nitrogen abundances can be closely associated with recent collisions and subsequent accretion of H I high velocity clouds (HVCs) that surround the Galaxy and have low nitrogen abundances. We show that if the observed low [N/H] is limited to very young stars with ages less than {approx}10{sup 7} yr, then the collision/accretion rate of the HVCs onto the LMC needs to be {approx}0.2 M{sub sun} yr{sup -1} (corresponding to the total HVC mass of 10{sup 6}-10{sup 7} M{sub sun}) to dilute the original interstellar medium (ISM) before star formation. The required accretion rate means that even if the typical mass of HVCs accreted onto the LMC is {approx}10{sup 7} M{sub sun}, the Galaxy needs to have {approx}2500 massive HVCs within the LMC's orbital radius with respect to the Galactic center. The rather large number of required massive HVCs drives us to suggest that the HVCs are not likely to efficiently dilute the ISM of the LMC and consequently lower the [N/H]. We thus suggest the transfer of gas with low [N/H] from the Small Magellanic Cloud to the LMC as a promising scenario that can explain the observed low [N/H].

  18. Natural gas monthly, April 1998

    SciTech Connect (OSTI)

    NONE

    1998-04-01T23:59:59.000Z

    This issue of the Natural Gas Monthly presents the most recent estimates of natural gas data from the Energy Information Administration (EIA). Estimates extend through April 1998 for many data series. The report highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, feature articles are presented designed to assist readers in using and interpreting natural gas information. This issue contains the special report, ``Natural Gas 1997: A Preliminary Summary.`` This report provides information on natural gas supply and disposition for the year 1997, based on monthly data through December from EIA surveys. 6 figs., 28 tabs.

  19. The Role of Electroweak Corrections for the Dark Matter Relic Abundance

    SciTech Connect (OSTI)

    Ciafaloni, Paolo [Dipartimento di Fisica, Università di Lecce and INFN - Sezione di Lecce, Via per Arnesano, I-73100 Lecce (Italy); Comelli, Denis [INFN - Sezione di Ferrara, Via Saragat 3, I-44100 Ferrara (Italy); Simone, Andrea De [CERN, PH-TH Division, CH-1211, Genève 23 (Switzerland); Morgante, Enrico; Riotto, Antonio [Département de Physique Théorique and Centre for Astroparticle Physics (CAP), 24 quai E. Ansermet, CH-1211 Genève (Switzerland); Urbano, Alfredo, E-mail: paolo.ciafaloni@le.infn.it, E-mail: comelli@fe.infn.it, E-mail: andrea.desimone@sissa.it, E-mail: enrico.morgante@unige.ch, E-mail: antonio.riotto@unige.ch, E-mail: alfredo.urbano@sissa.it [SISSA, Via Bonomea 265, I-34136 Trieste (Italy)

    2013-10-01T23:59:59.000Z

    We analyze the validity of the theorems concerning the cancellation of the infrared and collinar divergences in the case of dark matter freeze-out in the early universe. In particular, we compute the electroweak logarithmic corrections of infrared origin to the annihilation cross section of a dark matter particle being the neutral component of a SU(2){sub L} multiplet. The inclusion of processes with final state W can modify significantly the cross sections computed with only virtual W exchange. Our results show that the inclusion of infrared logs is necessary for a precise computation of the dark matter relic abundance.

  20. Solar abundances and helioseismology: fine structure spacings and separation ratios of low-degree p modes

    E-Print Network [OSTI]

    Sarbani Basu; William J. Chaplin; Yvonne Elsworth; Roger New; Aldo M. Serenelli; Graham A. Verner

    2006-10-02T23:59:59.000Z

    We have used 4752 days of data collected by the Birmingham Solar-Oscillations Network (BiSON) to determine very precise oscillation frequencies of acoustic low-degree modes that probe the solar core. We compare the fine (small frequency) spacings and frequency separation ratios formed from these data with those of different solar models. We find that models constructed with low metallicity are incompatible with the observations. The results provide strong support for lowering the theoretical uncertainties on the neutrino fluxes. These uncertainties had recently been raised due to the controversy over the solar abundances.

  1. X-ray Absorption Spectroscopy of the Multi-phase Interstellar Medium: Oxygen and Neon Abundances

    E-Print Network [OSTI]

    Yangsen Yao; Q. Daniel Wang

    2005-12-19T23:59:59.000Z

    X-ray absorption spectroscopy provides a potentially powerful tool in determining the metal abundances in various phases of the interstellar medium (ISM). We present a case study of the sight line toward 4U 1820-303 (Galactic coordinates l, b=2.79, -7.91 and distance = 7.6 kpc), based on Chandra Grating observations. The detection of OI, OII, OIII, OVII, OVIII, and NeIX Kalpha absorption lines allows us to measure the atomic column densities of the neutral, warm ionized, and hot phases of the ISM through much of the Galactic disk. By comparing these measurements with the 21 cm hydrogen emission and with the pulsar dispersion measure along the same sight line, we estimate the mean oxygen abundances in the neutral and total ionized phases as 0.3(0.2, 0.6) and 2.2(1.1, 3.5) in units of Anders & Grevesse (1989) solar value. This significant oxygen abundance difference is apparently a result of molecule/dust grain destruction and recent metal enrichment in the warm ionized and hot phases. We also measure the column density of neon from its absorption edge and obtain the Ne/O ratio of the neutral plus warm ionized gas as 2.1(1.3, 3.5) solar. Accounting for the expected oxygen contained in molecules and dust grains would reduce the Ne/O ratio by a factor of ~1.5. From a joint-analysis of the OVII, OVIII, and NeIX lines, we obtain the Ne/O abundance ratio of the hot phase as 1.4(0.9, 2.1) solar, which is not sensitive to the exact temperature distribution assumed in the absorption line modeling. These comparable ISM Ne/O ratios for the hot and cooler gas are thus considerably less than the value (2.85+-0.07; 1sigma) recently inferred from corona emission of solar-like stars (Drake & Testa 2005). (abridged)

  2. Seasonal Abundance and Dispersal of the Cotton Fleahopper as Related to Host Plant Phenology.

    E-Print Network [OSTI]

    Almand, Lyndon K.; Sterling, W.L.; Green, C.L.

    1976-01-01T23:59:59.000Z

    occurred. Croton served as a host plant both for overwintering eggs and throughout the growing season. Seasonal Abundance and Dispersal of the Cotton Fleahopper as Related to Host Plant Phenology *L. K. Almand W. L. Sterling C. L. Green... to various wind speeds also was de rmined in a wind tunnel with a testing area of about 3 lhic feet. Nymphs ;less than 24 hours old which had ltched from overwintering eggs (procedure developed I Sterling and Plapp, 1972) were collected for testing Id...

  3. A simple analytical model for the abundance of damped Ly-?absorbers

    E-Print Network [OSTI]

    T. Roy Choudhury; T. Padmanabhan

    2002-04-01T23:59:59.000Z

    A simple analytical model for estimating the fraction (\\Omega_{gas}) of matter in gaseous form within the collapsed dark matter (DM) haloes is presented. The model is developed using (i) the Press-Schechter formalism to estimate the fraction of baryons in DM haloes, and (ii) the observational estimates of the star formation rate at different redshifts. The prediction for \\Omega_{gas} from the model is in broad agreement with the observed abundance of the damped Ly-\\alpha systems. Furthermore, it can be used for estimating the circular velocities of the collapsed haloes at different redshifts, which could be compared with future observations.

  4. Microbial abundance and biomass in sediments of the Texas-Louisiana shelf

    E-Print Network [OSTI]

    Cruz-Kaegi, Marta Elizabeth

    1992-01-01T23:59:59.000Z

    MICROBIAL ABUNDANCF. AND BIOMASS IN SEDIMENTS OF THF. TEXAS-LOUISIANA SHELF A Thesis by MARTA ELIZABETH CRUZ-KAEGI Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfiument of the requirements for the degree... of MASTER OF SCIENCE December 1992 Major Subject: Oceanography MICROBIAL ABUNDANCE AND BIOMASS IN SEDIMENTS OF THE TEXAS-LOUISIANA SHELF A Thesis by MARTA ELIZABETH CRUZ-KAEGI Approved as to style and content by: I $7& Gilberl T. Rowe (Chair...

  5. Prompt Iron Enrichment, Two r-Process Components, and Abundances in Very Metal-Poor Stars

    E-Print Network [OSTI]

    G. J. Wasserburg; Y. -Z. Qian

    1999-11-30T23:59:59.000Z

    We present a model to explain the wide range of abundances for heavy r-process elements (mass number A > 130) at low [Fe/H]. This model requires rapid star formation and/or an initial population of supermassive stars in the earliest condensed clots of matter to provide a prompt or initial Fe inventory. Subsequent Fe and r-process enrichment was provided by two types of supernovae: one producing heavy r-elements with no Fe on a rather short timescale and the other producing light r-elements (A < or = 130) with Fe on a much longer timescale.

  6. HIGH PRECISION ABUNDANCES OF THE OLD SOLAR TWIN HIP 102152: INSIGHTS ON Li DEPLETION FROM THE OLDEST SUN

    SciTech Connect (OSTI)

    Monroe, TalaWanda R.; Melendez, Jorge; Tucci Maia, Marcelo; Freitas, Fabricio C. [Departamento de Astronomia do IAG/USP, Universidade de Sao Paulo, Rua do Matao 1226, Cidade Universitaria, 05508-900 Sao Paulo, SP (Brazil); Ramirez, Ivan [McDonald Observatory, The University of Texas at Austin, Austin, TX 78712 (United States); Yong, David; Asplund, Martin; Alves-Brito, Alan; Casagrande, Luca [Research School of Astronomy and Astrophysics, The Australian National University, Cotter Road, Weston, ACT 2611 (Australia); Bergemann, Maria [Max Planck Institute for Astrophysics, Postfach 1317, D-85741 Garching (Germany); Bedell, Megan; Bean, Jacob [Department of Astronomy and Astrophysics, University of Chicago, 5640 S. Ellis Ave., Chicago, IL 60637 (United States); Lind, Karin [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Castro, Matthieu; Do Nascimento, Jose-Dias [Departamento de Fisica Teorica e Experimental, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, RN (Brazil); Bazot, Michael, E-mail: tmonroe@usp.br [Centro de Astrofisica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal)

    2013-09-10T23:59:59.000Z

    We present the first detailed chemical abundance analysis of the old 8.2 Gyr solar twin, HIP 102152. We derive differential abundances of 21 elements relative to the Sun with precisions as high as 0.004 dex ({approx}<1%), using ultra high-resolution (R = 110,000), high S/N UVES spectra obtained on the 8.2 m Very Large Telescope. Our determined metallicity of HIP 102152 is [Fe/H] = -0.013 {+-} 0.004. The atmospheric parameters of the star were determined to be 54 K cooler than the Sun, 0.09 dex lower in surface gravity, and a microturbulence identical to our derived solar value. Elemental abundance ratios examined versus dust condensation temperature reveal a solar abundance pattern for this star, in contrast to most solar twins. The abundance pattern of HIP 102152 appears to be the most similar to solar of any known solar twin. Abundances of the younger, 2.9 Gyr solar twin, 18 Sco, were also determined from UVES spectra to serve as a comparison for HIP 102152. The solar chemical pattern of HIP 102152 makes it a potential candidate to host terrestrial planets, which is reinforced by the lack of giant planets in its terrestrial planet region. The following non-local thermodynamic equilibrium Li abundances were obtained for HIP 102152, 18 Sco, and the Sun: log {epsilon} (Li) = 0.48 {+-} 0.07, 1.62 {+-} 0.02, and 1.07 {+-} 0.02, respectively. The Li abundance of HIP 102152 is the lowest reported to date for a solar twin, and allows us to consider an emerging, tightly constrained Li-age trend for solar twin stars.

  7. The potential effect of sprinkle irrigation systems in ricelands on the occurrence and abundance of mosquito eggs

    E-Print Network [OSTI]

    Rankin, Steven Earl

    1984-01-01T23:59:59.000Z

    THE POTENTIAL EFFECT OF SPRINELE IRRIGATION SYSTEMS IN RICELANDS ON THE OCCURRENCE AND ABUNDANCE OF MOSQUITO EGGS A Thesis STEVEN EARL RANKIN Submitted to the Graduate College of Texas AAM University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE December 1984 Major Subject: Entcmology THE POTENTIAL EFFECT OF SPRINKLE IRRIGATION SYSTEMS IN' RICELANDS ON THE OCCURRENCE AND ABUNDANCE OF MOSQUITO EGGS A Thesis by STEVEN EARL RANKIN Approved as to style...

  8. The Effects of Site Characterization Activities on the Abundance of Ravens (Corvus corax) in the Yucca Mountain Area

    SciTech Connect (OSTI)

    P.E. Lederle

    1998-05-08T23:59:59.000Z

    In response to the Nuclear Waste Policy Act of 1982 and the Nuclear Waste Policy Amendments Act of 1987, the U.S. Department of Energy (DOE) developed and is implementing the Yucca Mountain Site Characterization Project. Raven abundance was measured from August 1991 through August 1995 along treatment and control routes to evaluate whether site characterization activities resulted in increased raven abundance at Yucca Mountain. This study fulfills the requirement set forth in the incidental take provisions of the Biological Opinion that DOE monitor the abundance of ravens at Yucca Mountain. Ravens were more abundant at Yucca Mountain than in the control area, and raven abundance in both areas increased over time. However, the magnitude of differences between Yucca Mountain and control surveys did not change over time, indicating that the increase in raven abundance observed during this study was not related to site characterization activities. Increases over time on both Yucca Mountain and control routes are consistent with increases in raven abundance in the Mojave Desert reported by the annual Breeding Bird Survey of the US. Fish and Wildlife Service. Evidence from the Desert Tortoise Monitoring Program at Yucca Mountain suggests that ravens are not a significant predator of small tortoises in this locale. Carcasses of small tortoises (less than 110 mm in length) collected during the study showed little evidence of raven predation, and 59 radiomarked hatchlings that were monitored on a regular basis were not preyed upon by ravens. Overall, no direct evidence of raven predation on tortoises was observed during this study. Small tortoises are probably encountered so infrequently by ravens that they are rarely exploited as a food source. This is likely due to the relatively low abundance of both desert tortoises and ravens in the Yucca Mountain area.

  9. Abundances in intermediate-mass AGB stars undergoing third dredge-up and hot-bottom burning

    E-Print Network [OSTI]

    J. A. McSaveney; P. R. Wood; M. Scholz; J. C. Lattanzio; K. H. Hinkle

    2007-04-15T23:59:59.000Z

    High dispersion near-infrared spectra have been taken of seven highly-evolved, variable, intermediate-mass (4-6 Msun) AGB stars in the LMC and SMC in order to look for C, N and O variations that are expected to arise from third dredge-up and hot-bottom burning. The pulsation of the objects has been modelled, yielding stellar masses, and spectral synthesis calculations have been performed in order to derive abundances from the observed spectra. For two stars, abundances of C, N, O, Na, Al, Ti, Sc and Fe were derived and compared with the abundances predicted by detailed AGB models. Both stars show very large N enhancements and C deficiencies. These results provide the first observational confirmation of the long-predicted production of primary nitrogen by the combination of third dredge-up and hot-bottom burning in intermediate-mass AGB stars. It was not possible to derive abundances for the remaining five stars: three were too cool to model, while another two had strong shocks in their atmospheres which caused strong emission to fill the line cores and made abundance determination impossible. The latter occurrence allows us to predict the pulsation phase interval during which observations should be made if successful abundance analysis is to be possible.

  10. s- and r-process element abundances in the CMD of 47 Tucanae using the Robert Stobie Spectrograph on SALT

    E-Print Network [OSTI]

    C. C. Worley; P. L. Cottrell; E. C. Wylie de Boer

    2008-02-04T23:59:59.000Z

    A recent study by Wylie et al 2006 has revealed that s-process element abundances are enhanced relative to iron in both red giant branch and asymptotic giant branch stars of 47 Tucanae. A more detailed investigation into s-process element abundances throughout the colour-magnitude diagram of 47 Tucanae is vital in order to determine whether the observed enhancements are intrinsic to the cluster. This paper explores this possibility through observational and theoretical means. The visibility of s- and r-process element lines in synthetic spectra of giant and dwarf stars throughout the colour magnitude diagram of 47 Tucanae has been explored. It was determined that a resolving power of 10 000 was sufficient to observe s-process element abundance variations in globular cluster giant branch stars. These synthetic results were compared with the spectra of eleven 47 Tucanae giant branch stars observed during the performance verification of the Robert Stobie Spectrograph on the Southern African Large Telescope. Three s-process elements, Zr, Ba, Nd, and one r-process element, Eu, were investigated. No abundance variations were found such that [X/Fe] = 0.0 +/- 0.5 dex. It was concluded that this resolving power, R ~ 5000, was not sufficient to obtain exact abundances but upper limits on the s-process element abundances could be determined.

  11. Correlations in thermal comfort and natural wind

    E-Print Network [OSTI]

    Kang, Ki-Nam; Song, Doosam; Schiavon, Stefano

    2013-01-01T23:59:59.000Z

    Chaotic ?uctuation in natural wind and its application toof natural and mechanical wind in built environment usingcharacteristics of natural wind. Refrigeration 71 (821),

  12. Natural Gas Reforming | Department of Energy

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

    Hydrogen Production Natural Gas Reforming Natural Gas Reforming Photo of Petroleum Refinery Natural gas reforming is an advanced and mature production process that builds upon...

  13. Permitted Oxygen Abundances and the Temperature Scale of Metal-Poor Turn-Off Stars

    E-Print Network [OSTI]

    J. Melendez; N. G. Shchukina; I. E. Vasiljeva; I. Ramirez

    2006-01-12T23:59:59.000Z

    We use high quality VLT/UVES published data of the permitted OI triplet and FeII lines to determine oxygen and iron abundances in unevolved (dwarfs, turn-off, subgiants) metal-poor halo stars. The calculations have been performed both in LTE and NLTE, employing effective temperatures obtained with the new infrared flux method (IRFM) temperature scale by Ramirez & Melendez, and surface gravities from Hipparcos parallaxes and theoretical isochrones. A new list of accurate transition probabilities for FeII lines, tied to the absolute scale defined by laboratory measurements, has been used. We find a plateau in the oxygen-to-iron ratio over more than two orders of magnitude in iron abundance (-3.2 < [Fe/H] < -0.7), with a mean [O/Fe] = 0.5 dex (sigma = 0.1 dex), independent of metallicity, temperature and surface gravity. According to the new IRFM Teff scale, the temperatures of turn-off halo stars strongly depend on metallicity, a result that is in excellent qualitative and quantitative agreement with stellar evolution calculations, which predict that the Teff of the turn-off at [Fe/H] = -3 is about 600-700 K higher than that at [Fe/H] = -1.

  14. History of Milky Way Dwarf Spheroidal Galaxies Imprinted on Abundance Patterns of Neutron-Capture Elements

    E-Print Network [OSTI]

    Takuji Tsujimoto; Toshikazu Shigeyama

    2002-05-02T23:59:59.000Z

    Stellar abundance pattern of neutron-capture elements such as barium is used as a powerful tool to infer how star formation proceeded in dwarf spheroidal (dSph) galaxies. It is found that the abundance correlation of barium with iron in stars belonging to dSph galaxies orbiting the Milky Way, i.e., Draco, Sextans, and Ursa Minor have a feature similar to the barium-iron correlation in Galactic metal-poor stars. The common feature of these two correlations can be realized by our inhomogeneous chemical evolution model based on the supernova-driven star formation scenario if dSph stars formed from gas with a velocity dispersion of ~26 km/s. This velocity dispersion together with the stellar luminosities strongly suggest that dark matter dominated dSph galaxies. The tidal force of the Milky Way links this velocity dispersion with the currently observed value <10 km/s by stripping the dark matter in dSph galaxies. As a result, the total mass of each dSph galaxy is found to have been originally ~25 times larger than at present. Our inhomogeneous chemical evolution model succeeds in reproducing the stellar [Fe/H] distribution function observed in Sextans. In this model, supernovae immediately after the end of the star formation epoch can expel the remaining gas over the gravitational potential of the dSph galaxy.

  15. What are little worlds made of? Stellar abundances and the building blocks of planets

    E-Print Network [OSTI]

    Gaidos, Eric

    2015-01-01T23:59:59.000Z

    If the photospheres of solar-type stars represent the composition of circumstellar disks from which any planets formed, spectroscopic determinations of stellar elemental abundances offer information on the composition of those planets, including smaller, rocky planets. In particular, the C/O ratio is proposed to be a key determinant of the composition of solids that condense from disk gas and are incorporated into planets. Also, planets may leave chemical signatures on the photospheres of their host stars by sequestering heavy elements, or by being accreted by the stars. The presence, absence, and composition of planets could be revealed by small differences in the relative abundances between stars. I critically examine these scenarios and show that (i) a model of Galactic chemical evolution predicts that the C/O ratio is expected to be close to the solar value and vary little between dwarf stars in the solar neighborhood; (ii) spectroscopic surveys of M dwarf stars limit the occurrence of stars with C/O $\\gt...

  16. Chemical Abundances in NGC 5053: A Very Metal-Poor and Dynamically Complex Globular Cluster

    E-Print Network [OSTI]

    Boberg, Owen M; Vesperini, Enrico

    2015-01-01T23:59:59.000Z

    NGC 5053 provides a rich environment to test our understanding of the complex evolution of globular clusters (GCs). Recent studies have found that this cluster has interesting morphological features beyond the typical spherical distribution of GCs, suggesting that external tidal effects have played an important role in its evolution and current properties. Additionally, simulations have shown that NGC 5053 could be a likely candidate to belong to the Sagittarius dwarf galaxy (Sgr dSph) stream. Using the Wisconsin-Indiana-Yale-NOAO-Hydra multi-object spectrograph, we have collected high quality (signal-to-noise ratio $\\sim$ 75-90), medium-resolution spectra for red giant branch stars in NGC 5053. Using these spectra we have measured the Fe, Ca, Ti, Ni, Ba, Na, and O abundances in the cluster. We measure an average cluster [Fe/H] abundance of -2.45 with a standard deviation of 0.04 dex, making NGC 5053 one of the most metal-poor GCs in the Milky Way (MW). The [Ca/Fe], [Ti/Fe], and [Ba/Fe] we measure are consist...

  17. ON THE ORIGIN OF THE SLOW SPEED SOLAR WIND: HELIUM ABUNDANCE VARIATIONS

    SciTech Connect (OSTI)

    Rakowski, Cara E.; Laming, J. Martin [Space Science Division, Naval Research Laboratory Code 7674L, Washington, DC 20375 (United States)

    2012-07-20T23:59:59.000Z

    The first ionization potential (FIP) effect is the by now well-known enhancement in abundance over photospheric values of Fe and other elements with FIP below about 10 eV observed in the solar corona and slow speed solar wind. In our model, this fractionation is achieved by means of the ponderomotive force, arising as Alfven waves propagate through or reflect from steep density gradients in the solar chromosphere. This is also the region where low FIP elements are ionized, and high FIP elements are largely neutral leading to the fractionation as ions interact with the waves but neutrals do not. Helium, the element with the highest FIP and consequently the last to remain neutral as one moves upward, can be depleted in such models. Here, we investigate this depletion for varying loop lengths and magnetic field strengths. Variations in this depletion arise as the concentration of the ponderomotive force at the top of the chromosphere varies in response to Alfven wave frequency with respect to the resonant frequency of the overlying coronal loop, the magnetic field, and possibly also the loop length. We find that stronger depletions of He are obtained for weaker magnetic field, at frequencies close to or just above the loop resonance. These results may have relevance to observed variations of the slow wind solar He abundance with wind speed, with slower slow speed solar wind having a stronger depletion of He.

  18. Magneto-convective models of red dwarfs: constraints imposed by the lithium abundance

    E-Print Network [OSTI]

    MacDonald, J

    2015-01-01T23:59:59.000Z

    Magnetic fields impede the onset of convection, thereby altering the thermal structure of a convective envelope in a low mass star: this has an effect on the amount of lithium depletion in a magnetized star. In order to quantify this effect, we have applied a magneto-convective model to two low mass stars for which lithium abundances and precise structural parameters are known: YY Gem and CU Cnc. For both stars, we have obtained models which satisfy empirical constraints on the following parameters: R, L, surface magnetic field strength, and Li abundance. In the case of YY Gem, we have obtained a model which satisfies the empirical constraints with an internal magnetic field of several megagauss: such a field strength is within the range of a dynamo where the field energy is in equipartition with rotational energy deep inside the convection zone. However, in the case of CU Cnc, the Li requires an internal magnetic field which is probably too strong for a dynamo origin: we suggest possible alternatives which m...

  19. THE FIRST FLUORINE ABUNDANCE DETERMINATIONS IN EXTRAGALACTIC ASYMPTOTIC GIANT BRANCH CARBON STARS

    SciTech Connect (OSTI)

    Abia, C.; Cristallo, S.; Dominguez, I. [Dpto. Fisica Teorica y del Cosmos, Universidad de Granada, 18071 Granada (Spain); Cunha, K.; Smith, V. V. [National Optical Astronomy Observatory, P.O. Box 26732, Tucson, AZ 85726 (United States); De Laverny, P.; Recio-Blanco, A. [University of Nice-Sophia Antipolis, CNRS (UMR 6202), Cassiopee, Observatoire de la Cote d'Azur, B.P. 4229, 06304 Nice Cedex 4 (France); Straniero, O., E-mail: cabia@ugr.es [INAF-Osservatorio di Collurania, 64100 Teramo (Italy)

    2011-08-10T23:59:59.000Z

    Fluorine ({sup 19}F) abundances (or upper limits) are derived in six extragalactic asymptotic giant branch (AGB) carbon stars from the HF(1-0) R9 line at 2.3358 {mu}m in high-resolution spectra. The stars belong to the Local Group galaxies, Large Magellanic Cloud, Small Magellanic Cloud, and Carina dwarf spheroidal, spanning more than a factor of 50 in metallicity. This is the first study to probe the behavior of F with metallicity in intrinsic extragalactic C-rich AGB stars. Fluorine could be measured only in four of the target stars, showing a wide range in F enhancements. Our F abundance measurements together with those recently derived in Galactic AGB carbon stars show a correlation with the observed carbon and s-element enhancements. The observed correlations, however, display a different dependence on the stellar metallicity with respect to theoretical predictions in low-mass, low-metallicity AGB models. We briefly discuss the possible reasons for this discrepancy. If our findings are confirmed in a larger number of metal-poor AGBs, the issue of F production in AGB stars will need to be revisited.

  20. A New and Simple Approach to Determine the Abundance of Hydrogen Molecules on Interstellar Ice Mantles

    E-Print Network [OSTI]

    Hincelin, Ugo; Herbst, Eric

    2014-01-01T23:59:59.000Z

    Water is usually the main component of ice mantles, which cover the cores of dust grains in cold portions of dense interstellar clouds. When molecular hydrogen is adsorbed onto an icy mantle through physisorption, a common assumption in gas-grain rate equation models is to use an adsorption energy for molecular hydrogen on a pure water substrate. However, at high density and low temperature, when H2 is efficiently adsorbed onto the mantle, its surface abundance can be strongly overestimated if this assumption is still used. Unfortunately, the more detailed microscopic Monte Carlo treatment cannot be used to study the abundance of H2 in ice mantles if a full gas-grain network is utilized. We present a numerical method adapted for rate-equation models that takes into account the possibility that an H2 molecule can, while diffusing on the surface, find itself bound to another hydrogen molecule, with a far weaker bond than the H2-water bond, which can lead to more efficient desorption. We label the ensuing desorp...

  1. A correlation between light profile and [Mg/Fe] abundance ratio in early-type galaxies

    E-Print Network [OSTI]

    Alexandre Vazdekis; Ignacio Trujillo; Yoshihiko Yamada

    2003-11-27T23:59:59.000Z

    We explore possible correlations between light profile shapes, as parameterized by the Sersic index or the concentration index C_re(1/3), and relevant stellar population parameters in early-type galaxies. Mean luminosity weighted ages, metallicities and abundance ratios were obtained from spectra of very high signal-to-noise and stellar population models that synthesize galaxy spectra at the resolution given by their velocity dispersions, in combination with an age indicator that is virtually free of the effects of metallicity. We do not find any significant correlation between the Sersic index (or C_re(1/3)) and mean age or metallicity, but a strong positive correlation of the shape parameters with [Mg/Fe] abundance ratio. This dependence is as strong as the [Mg/Fe] vs. velocity dispersion and C_re(1/3) vs. velocity dispersion relations. We speculate that early-type galaxies settle up their structure on time-scales in agreement with those imposed by their [Mg/Fe] ratios. This suggest that the global structure of larger galaxies, with larger [Mg/Fe] ratios and shorter time-scales, was already at place at high z, without experiencing a significant time evolution.

  2. ISO spectroscopy of compact HII regions in the Galaxy. II Ionization and elemental abundances

    E-Print Network [OSTI]

    N. L. Martin-Hernandez; E. Peeters; C. Morisset; A. G. G. M. Tielens; P. Cox; P. R. Roelfsema; J. -P. Baluteau; D. Schaerer; J. S. Mathis; F. Damour; E. Churchwell; M. F. Kessler

    2001-10-30T23:59:59.000Z

    Based on the ISO spectral catalogue of compact HII regions by Peeters et al. (2001), we present a first analysis of the hydrogen recombination and atomic fine-structure lines originated in the ionized gas. The sample consists of 34 HII regions located at galactocentric distances between Rgal = 0 and 15 kpc. The SWS HI recombination lines between 2 and 8 mum are used to estimate the extinction law at these wavelengths for 14 HII regions. An extinction in the K band between 0 and $\\sim$ 3 mag. has been derived. The fine-structure lines of N, O, Ne, S and Ar are detected in most of the sources. Most of these elements are observed in two different ionization stages probing a range in ionization potential up to 41 eV. The ISO data, by itself or combined with radio data taken from the literature, is used to derive the elemental abundances relative to hydrogen. The present data thus allow us to describe for each source its elemental abundance, its state of ionization and to constrain the properties of the ionizing star(s).

  3. Heat distribution by natural convection

    SciTech Connect (OSTI)

    Balcomb, J.D.

    1985-01-01T23:59:59.000Z

    Natural convection can provide adequate heat distribution in many situations that arise in buildings. This is appropriate, for example, in passive solar buildings where some rooms tend to be more strongly solar heated than others. Natural convection can also be used to reduce the number of auxiliary heating units required in a building. Natural airflow and heat transport through doorways and other internal building apertures are predictable and can be accounted for in the design. The nature of natural convection is described, and a design chart is presented appropriate to a simple, single-doorway situation. Experimental results are summarized based on the monitoring of 15 passive solar buildings which employ a wide variety of geometrical configurations including natural convective loops.

  4. Nature of eclipsing pulsars

    E-Print Network [OSTI]

    David Khechinashvili; George Melikidze; Janusz Gil

    2000-01-08T23:59:59.000Z

    We present a model for pulsar radio eclipses in some binary systems, and test this model for PSRs B1957+20 and J2051-0827. We suggest that in these binaries the companion stars are degenerate dwarfs with strong surface magnetic fields. The magnetospheres of these stars are permanently infused by the relativistic particles of the pulsar wind. We argue that the radio waves emitted by the pulsar split into the eigenmodes of the electron-positron plasma as they enter the companion's magnetosphere and are then strongly damped due to cyclotron resonance with the ambient plasma particles. Our model explains in a natural way the anomalous duration and behavior of radio eclipses observed in such systems. In particular, it provides stable, continuous, and frequency-dependent eclipses, in agreement with the observations. We predict a significant variation of linear polarization both at eclipse ingress and egress. In this paper we also suggest several possible mechanisms of generation of the optical and $X$-ray emission observed from these binary systems.

  5. Naturalness and supersymmetry

    SciTech Connect (OSTI)

    Agashe, K [Lawrence Berkeley National Lab., CA (United States). Theoretical Physics Group

    1998-05-01T23:59:59.000Z

    In this thesis, the author argues that the supersymmetric Standard Model, while avoiding the fine tuning in electroweak symmetry breaking, requires unnaturalness/fine tuning in some (other) sector of the theory. For example, Baryon and Lepton number violating operators are allowed which lead to proton decay and flavor changing neutral currents. He studies some of the constraints from the latter in this thesis. He has to impose an R-parity for the theory to be both natural and viable. In the absence of flavor symmetries, the supersymmetry breaking masses for the squarks and sleptons lead to too large flavor changing neutral currents. He shows that two of the solutions to this problem, gauge mediation of supersymmetry breaking and making the scalars of the first two generations heavier than a few TeV, reintroduce fine tuning in electroweak symmetry breaking. He also constructs a model of low energy gauge mediation with a non-minimal messenger sector which improves the fine tuning and also generates required Higgs mass terms. He shows that this model can be derived from a Grand Unified Theory despite the non-minimal spectrum.

  6. Super-Natural MSSM

    E-Print Network [OSTI]

    Du, Guangle; Nanopoulos, D V; Raza, Shabbar

    2015-01-01T23:59:59.000Z

    We point out that the electroweak fine-tuning problem in the supersymmetric Standard Models (SSMs) is mainly due to the high energy definition of the fine-tuning measure. We propose super-natural supersymmetry which has an order one high energy fine-tuning measure automatically. The key point is that all the mass parameters in the SSMs arise from a single supersymmetry breaking parameter. In this paper, we show that there is no supersymmetry electroweak fine-tuning problem explicitly in the Minimal SSM (MSSM) with no-scale supergravity and Giudice-Masiero (GM) mechanism. We demonstrate that the $Z$-boson mass, the supersymmteric Higgs mixing parameter $\\mu$ at the unification scale, and the sparticle spectrum can be given as functions of the universal gaugino mass $M_{1/2}$. Because the light stau is the lightest supersymmetric particle (LSP) in the no-scale MSSM, to preserve $R$ parity, we introduce a non-thermally generated axino as the LSP dark matter candidate. We estimate the lifetime of the light stau b...

  7. Nature of eclipsing pulsars

    E-Print Network [OSTI]

    Khechinashvili, D; Gil, J; Khechinashvili, David; Melikidze, George; Gil, Janusz

    2000-01-01T23:59:59.000Z

    We present a model for pulsar radio eclipses in some binary systems, and test this model for PSRs B1957+20 and J2051-0827. We suggest that in these binaries the companion stars are degenerate dwarfs with strong surface magnetic fields. The magnetospheres of these stars are permanently infused by the relativistic particles of the pulsar wind. We argue that the radio waves emitted by the pulsar split into the eigenmodes of the electron-positron plasma as they enter the companion's magnetosphere and are then strongly damped due to cyclotron resonance with the ambient plasma particles. Our model explains in a natural way the anomalous duration and behavior of radio eclipses observed in such systems. In particular, it provides stable, continuous, and frequency-dependent eclipses, in agreement with the observations. We predict a significant variation of linear polarization both at eclipse ingress and egress. In this paper we also suggest several possible mechanisms of generation of the optical and $X$-ray emission ...

  8. Natural gas monthly, March 1998

    SciTech Connect (OSTI)

    NONE

    1998-03-01T23:59:59.000Z

    The March 1998 edition of the Natural Gas Monthly highlights activities, events, and analyses associated with the natural gas industry. Volume and price data are presented for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. This report also features an article on the correction of errors in the drilling activity estimates series, and in-depth drilling activity data. 6 figs., 28 tabs.

  9. Natural gas monthly, April 1994

    SciTech Connect (OSTI)

    Not Available

    1994-04-26T23:59:59.000Z

    The National Gas Monthly (NGM) highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information.

  10. Natural gas monthly, February 1994

    SciTech Connect (OSTI)

    Not Available

    1994-02-25T23:59:59.000Z

    The NGM highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. The NGM also features articles designed to assist readers in using and interpreting natural gas information.

  11. Natural gas monthly, May 1995

    SciTech Connect (OSTI)

    NONE

    1995-05-24T23:59:59.000Z

    The NGM highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information.

  12. Natural gas monthly, September 1998

    SciTech Connect (OSTI)

    NONE

    1998-09-01T23:59:59.000Z

    The National Gas Monthly (NGM) highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information. 6 figs., 27 tabs.

  13. Natural gas monthly, January 1994

    SciTech Connect (OSTI)

    Not Available

    1994-02-01T23:59:59.000Z

    The Natural Gas Monthly (NGM) highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information. The featured article for this month is on US coalbed methane production.

  14. ,"New Mexico Natural Gas Prices"

    U.S. Energy Information Administration (EIA) Indexed Site

    ,"Worksheet Name","Description"," Of Series","Frequency","Latest Data for" ,"Data 1","New Mexico Natural Gas Prices",8,"Monthly","12015","1151989" ,"Release Date:","331...

  15. Natural gas monthly, August 1997

    SciTech Connect (OSTI)

    NONE

    1997-08-01T23:59:59.000Z

    This report presents information on natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported.

  16. on man, nature & air pollution

    E-Print Network [OSTI]

    Finlayson-Pitts, Barbara J

    2008-01-01T23:59:59.000Z

    on man, nature & air pollution About three decades ago, itand episodes of air pollution the following summer. Wetthe increase in air pollution. This hypothesis generated

  17. Natural Gas Pipeline Safety (Kansas)

    Broader source: Energy.gov [DOE]

    This article states minimum safety standards for the transportation of natural gas by pipeline and reporting requirements for operators of pipelines.

  18. Natural Gas Pipeline Utilities (Maine)

    Broader source: Energy.gov [DOE]

    These regulations apply to entities seeking to develop and operate natural gas pipelines and provide construction requirements for such pipelines. The regulations describe the authority of the...

  19. Scientific and Natural Areas (Minnesota)

    Broader source: Energy.gov [DOE]

    Certain scientific and natural areas are established throughout the state for the purpose of preservation and protection. Construction and new development is prohibited in these areas.

  20. Renewable Natural Gas- Developer Perspective

    Broader source: Energy.gov [DOE]

    Breakout Session 3-C: Renewable Gaseous FuelsRenewable Natural Gas - Developer PerspectiveDavid Ross, Managing Director, MultiGen International, LLC