Sample records for disc call 1-800-stat-usa

  1. From discs to planetesimals I: evolution of gas and dust discs

    E-Print Network [OSTI]

    Richard Alexander

    2007-12-03T23:59:59.000Z

    I review the processes that shape the evolution of protoplanetary discs around young, solar-mass stars. I first discuss observations of protoplanetary discs, and note in particular the constraints these observations place on models of disc evolution. The processes that affect the evolution of gas discs are then discussed, with the focus in particular on viscous accretion and photoevaporation, and recent models which combine the two. I then discuss the dynamics and growth of dust grains in discs, considering models of grain growth, the gas-grain interaction and planetesimal formation, and review recent research in this area. Lastly, I consider the so-called "transitional" discs, which are thought to be observed during disc dispersal. Recent observations and models of these systems are reviewed, and prospects for using statistical surveys to distinguish between the various proposed models are discussed.

  2. Thin discs, thick discs and transition zones

    E-Print Network [OSTI]

    Guillaume Dubus

    2002-06-13T23:59:59.000Z

    Accretion onto a compact object must occur through a disc when the material has some initial angular momentum. Thin discs and the thicker low radiative efficiency accretion flows are solutions to this problem that have been widely studied and applied. This is an introduction to these accretion flows within the context of X-ray binaries and cataclysmic variables.

  3. Call Me! Calling the Glacier

    E-Print Network [OSTI]

    Laar, Kalle

    2009-01-01T23:59:59.000Z

    time to the Vernagtferner Glacier in the Oetztal Valley,Call Me! Calling the Glacier Kalle Laar Rudolf von Hirschpart of it, Calling the Glacier, which connects you in real

  4. Turbulent protostellar discs

    E-Print Network [OSTI]

    Axel Brandenburg

    2008-08-07T23:59:59.000Z

    Aspects of turbulence in protostellar accretion discs are being reviewed. The emergence of dead zones due to poor ionization and alternatives to the magneto-rotational instability are discussed. The coupling between dust and gas in protostellar accretion discs is explained and turbulent drag is compared with laminar drag in the Stokes and Epstein regimes. Finally, the significance of magnetic field generation in turbulent discs is emphasized in connection with driving outflows and with star-disc coupling.

  5. Turbine disc sealing assembly

    DOE Patents [OSTI]

    Diakunchak, Ihor S.

    2013-03-05T23:59:59.000Z

    A disc seal assembly for use in a turbine engine. The disc seal assembly includes a plurality of outwardly extending sealing flange members that define a plurality of fluid pockets. The sealing flange members define a labyrinth flow path therebetween to limit leakage between a hot gas path and a disc cavity in the turbine engine.

  6. Black hole accretion discs

    E-Print Network [OSTI]

    Lasota, Jean-Pierre

    2015-01-01T23:59:59.000Z

    This is an introduction to models of accretion discs around black holes. After a presentation of the non-relativistic equations describing the structure and evolution of geometrically thin accretion discs we discuss their steady-state solutions and compare them to observation. Next we describe in detail the thermal-viscous disc instability model and its application to dwarf novae for which it was designed and its X-ray irradiated-disc version which explains the soft X--ray transients, i.e. outbursting black-hole low-mass X-ray binaries. We then turn to the role of advection in accretion flow onto black holes illustrating its action and importance with a toy model describing both ADAFs and slim discs. We conclude with a presentation of the general-relativistic formalism describing accretion discs in the Kerr space-time.

  7. The Photoevaporation of Discs Around Young Stars in Massive Clusters

    E-Print Network [OSTI]

    C. J. Clarke

    2007-02-05T23:59:59.000Z

    We present models in which the photoevaporation of discs around young stars by an external ultraviolet source (as computed by Adams et al 2004) is coupled with the internal viscous evolution of the discs. These models are applied to the case of the Orion Nebula Cluster, where the presence of a strong ultraviolet field from the central OB stars, together with a detailed census of circumstellar discs and photoevaporative flows, is well established. In particular we investigate the constraints that are placed on the initial disc properties in the ONC by the twin requirement that most stars possess a disc on a scale of a few A.U., but that only a minority ($ 0.1 M_\\odot$). The ubiquity of discs on a small scale, on the other hand, mainly constrains the timespan over which the discs have been exposed to the ultraviolet field ($< 2 $Myr). We argue that the discs that are resolved by HST represent a population of discs in which self-gravity was important at the time that the dominant central OB star switched on, but that, according to our models, self-gravity is unlikely to be important in these discs at the present time. We discuss the implications of our results for the so-called proplyd lifetime problem.

  8. Disc-Disc Encounters between Low-Mass Protoplanetary Accretion Discs

    E-Print Network [OSTI]

    S. Pfalzner; S. Umbreit; Th. Henning

    2005-04-27T23:59:59.000Z

    Simulations of the collapse and fragmentation of turbulent molecular clouds and dense young clusters show that encounters between disc-surrounded stars are relatively common events which should significantly influence the resulting disc structure. In turn this should alter the accretion rate of disc matter onto the star and the conditions under which planet formation occurs. Although the effects of star-disc encounters have been previously investigated, very little is known about encounters where both stars are surrounded by discs. In this paper encounters of such disc-disc systems are studied quantitatively. It is found that for low-mass discs ($M_D$= 0.01 $M_\\sun$) the results from star-disc encounters can be straightforwardly generalized to disc-disc encounters as long as there is no mass transport between the discs. Differences to star-disc encounters occur naturally where significant amounts of matter are transported between the discs. In this case it is found that although the mass distribution does not change significantly, matter caught onto highly eccentric orbits is transported surprisingly far inside the disc. The captured mass partly replenishes the disc, but has a much lower angular momentum. This can lead to a reduction of the angular momentum in the entire disc and thus considerably increased accretion shortly after the encounter as well as in the long term.

  9. Radiation from Dwarf Nova Discs

    E-Print Network [OSTI]

    Irit Idan; Jean-Pierre Lasota; Jean-Marie Hameury; Giora Shaviv

    1998-06-04T23:59:59.000Z

    We use the Shaviv and Wehrse (1991) code to model the vertical structure and the emission properties of quiescent dwarf nova discs. We find that in the case of HT Cas the quiescent disc must be optically thin, in contradiction with the requirements of the standard disc instability model. We find a viscosity parameter alpha > 1. Although this is much less than values (~ 100) obtained in isothermal slab models it is not consistent with the accretion disc model assumptions.

  10. Self-gravitating accretion discs

    E-Print Network [OSTI]

    G. Lodato

    2008-01-25T23:59:59.000Z

    I review recent progresses in the dynamics and the evolution of self-gravitating accretion discs. Accretion discs are a fundamental component of several astrophysical systems on very diverse scales, and can be found around supermassive black holes in Active Galactic Nuclei (AGN), and also in our Galaxy around stellar mass compact objects and around young stars. Notwithstanding the specific differences arising from such diversity in physical extent, all these systems share a common feature where a central object is fed from the accretion disc, due to the effect of turbulence and disc instabilities, which are able to remove the angular momentum from the gas and allow its accretion. In recent years, it has become increasingly apparent that the gravitational field produced by the disc itself (the disc's self-gravity) is an important ingredient in the models, especially in the context of protostellar discs and of AGN discs. Indeed, it appears that in many cases (and especially in the colder outer parts of the disc) the development of gravitational instabilities can be one of the main agents in the redistribution of angular momentum. In some cases, the instability can be strong enough to lead to the formation of gravitationally bound clumps within the disc, and thus to determine the disc fragmentation. As a result, progress in our understanding of the dynamics of self-gravitating discs is essential to understand the processes that lead to the feeding of both young stars and of supermassive black holes in AGN. At the same time, understanding the fragmentation conditions is important to determine under which conditions AGN discs would fragment and form stars and whether protostellar discs might form giant gaseous planets through disc fragmentation.

  11. Warp propagation in astrophysical discs

    E-Print Network [OSTI]

    Nixon, Chris

    2015-01-01T23:59:59.000Z

    Astrophysical discs are often warped, that is, their orbital planes change with radius. This occurs whenever there is a non-axisymmetric force acting on the disc, for example the Lense-Thirring precession induced by a misaligned spinning black hole, or the gravitational pull of a misaligned companion. Such misalignments appear to be generic in astrophysics. The wide range of systems that can harbour warped discs - protostars, X-ray binaries, tidal disruption events, quasars and others - allows for a rich variety in the disc's response. Here we review the basic physics of warped discs and its implications.

  12. Enclosed rotary disc air pulser

    DOE Patents [OSTI]

    Olson, A. L. (Idaho Falls, ID); Batcheller, Tom A. (Idaho Falls, ID); Rindfleisch, J. A. (Arco, ID); Morgan, John M. (Arco, ID)

    1989-01-01T23:59:59.000Z

    An enclosed rotary disc air pulser for use with a solvent extraction pulse olumn includes a housing having inlet, exhaust and pulse leg ports, a shaft mounted in the housing and adapted for axial rotation therein, first and second disc members secured to the shaft within the housing in spaced relation to each other to define a chamber therebetween, the chamber being in communication with the pulse leg port, the first disc member located adjacent the inlet port, the second disc member being located adjacent the exhaust port, each disc member having a milled out portion, the disc members positioned on the shaft so that as the shaft rotates, the milled out portions permit alternative cyclical communication between the inlet port and the chamber and the exhaust port and the chamber.

  13. Volume One Disc Two

    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:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron SpinPrincetonUsing Maps1 -Visualizing Brain Metals inVolume-One-Disc-Two

  14. Gravitating discs around black holes

    E-Print Network [OSTI]

    V. Karas; J. -M. Hure; O. Semerak

    2004-01-16T23:59:59.000Z

    Fluid discs and tori around black holes are discussed within different approaches and with the emphasis on the role of disc gravity. First reviewed are the prospects of investigating the gravitational field of a black hole--disc system by analytical solutions of stationary, axially symmetric Einstein's equations. Then, more detailed considerations are focused to middle and outer parts of extended disc-like configurations where relativistic effects are small and the Newtonian description is adequate. Within general relativity, only a static case has been analysed in detail. Results are often very inspiring, however, simplifying assumptions must be imposed: ad hoc profiles of the disc density are commonly assumed and the effects of frame-dragging and completely lacking. Astrophysical discs (e.g. accretion discs in active galactic nuclei) typically extend far beyond the relativistic domain and are fairly diluted. However, self-gravity is still essential for their structure and evolution, as well as for their radiation emission and the impact on the environment around. For example, a nuclear star cluster in a galactic centre may bear various imprints of mutual star--disc interactions, which can be recognised in observational properties, such as the relation between the central mass and stellar velocity dispersion.

  15. Tidally-induced warps in protostellar discs

    E-Print Network [OSTI]

    C. Terquem; J. Papaloizou; R. Nelson

    1998-10-01T23:59:59.000Z

    We review results on the dynamics of warped gaseous discs. We consider tidal perturbation of a Keplerian disc by a companion star orbiting in a plane inclined to the disc. The perturbation induces the precession of the disc, and thus of any jet it could drive. In some conditions the precession rate is uniform, and as a result the disc settles into a warp mode. The tidal torque also leads to the truncation of the disc, to the evolution of the inclination angle (not necessarily towards alignment of the disc and orbital planes) and to a transport of angular momentum in the disc. We note that the spectral energy distribution of such a warped disc is different from that of a flat disc. We conclude by listing observational effects of warps in protostellar discs.

  16. Web Interface Call Simulator

    E-Print Network [OSTI]

    Ernst, Damien

    Web Interface Call Simulator Stage Description Web Interface for VoIP Call Simulator Net) Version 1.0 ­ 3/09/2012 Page 1 of 6 #12;Web Interface Call Simulator Version 1.0 ­ 3/09/2012 Page 2 of 6 #12;Web Interface Call Simulator Document Control Version Date Notes 1.0 25/8/2012 Reviewed

  17. Kinematic Detection of the Galactic Nuclear Disc

    E-Print Network [OSTI]

    Schönrich, Ralph; Sale, Stuart E

    2015-01-01T23:59:59.000Z

    We report the detection of the Galactic nuclear disc in line-of-sight kinematics of stars, measured with infrared spectroscopy from APOGEE. The nuclear disc is found to have a rotation velocity V ~ 120km/s comparable to the gas disc. The current data suggest that this disc is kinematically quite cold and has a small vertical extent of order 50pc. The stellar kinematics suggest a truncation radius of the stellar disc at a galactocentric radius R ~ 150pc, and provide tentative evidence for an overdensity at the position of the ring found in the molecular gas disc.

  18. DISC-UK DataShare 

    E-Print Network [OSTI]

    Rice, Robin

    DISC-UK DataShare (http://www.disc-uk.org/datashare.html) is a JISC-funded collaborative project led by EDINA and Edinburgh University Data Library, with the Universities of Oxford and Southampton as partners, and the ...

  19. Computer animation via optical video disc

    E-Print Network [OSTI]

    Bender, Walter

    1981-01-01T23:59:59.000Z

    This paper explores the notion of marrying two technologies: raster-scan computer animation and optical video discs. Animated sequences, generated at non real-time rates, then transfered to video disc, can be recalled under ...

  20. Physics and chemistry of gas in discs 

    E-Print Network [OSTI]

    Tilling, Ian

    2013-11-28T23:59:59.000Z

    Protoplanetary discs set the initial conditions for planet formation. By combining observations with detailed modelling, it is possible to constrain the physics and chemistry in such discs. I have used the detailed ...

  1. Thin, thick and dark discs in LCDM

    E-Print Network [OSTI]

    J. I. Read; G. Lake; O. Agertz; Victor P. Debattista

    2008-06-26T23:59:59.000Z

    In a LCDM cosmology, the Milky Way accretes satellites into the stellar disc. We use cosmological simulations to assess the frequency of near disc plane and higher inclination accretion events, and collisionless simulations of satellite mergers to quantify the final state of the accreted material and the effect on the thin disc. On average, a Milky Way-sized galaxy has 3 subhalos with vmax>80km/s; 7 with vmax>60km/s; and 15 with vmax>40km/s merge at redshift z>1. Assuming isotropic accretion, a third of these merge at an impact angle disc plane by dynamical friction. Their accreted stars and dark matter settle into a thick disc. The stellar thick disc qualitatively reproduces the observed thick disc at the solar neighbourhood, but is less massive by a factor ~2-10. The dark matter disc contributes 0.25-1 times the halo density at the solar position. Although not likely to be dynamically interesting, the dark disc has important implications for the direct detection of dark matter because of its low velocity with respect to the Earth. Higher inclination encounters (>20 degrees) are twice as likely as low inclination ones. These lead to structures that closely resemble the recently discovered inner/outer stellar halos. They also do more damage to the Milky Way stellar disc creating a more pronounced flare, and warp; both long-lived and consistent with current observations. The most massive mergers (vmax>80km/s) heat the thin disc enough to produce a thick disc. These heated thin disc stars are essential for obtaining a thick disc as massive as that seen in the Milky Way; they likely comprise some ~50-90% of the thick disc stars. The Milky Way thin disc must reform from fresh gas after z=1 [abridged].

  2. The Warped Disc of NGC 4258

    E-Print Network [OSTI]

    Rebecca G. Martin

    2008-04-07T23:59:59.000Z

    We consider the properties of the warped accretion disc in NGC 4258 which is delineated by maser emission. We use our analytical models to consider whether the disc could be warped by Lense-Thirring precession. We show that such models fit the shape of the disc well and we determine the goodness of fit for various combinations of the warp radius and the disc and black hole configurations. Though the fits are compelling evidence, we note that such a model has implications for the formation and longevity of the disc which might be problematic for the current understanding of Seyfert Galaxies.

  3. BOMB THREAT CALL PROCEDURES

    E-Print Network [OSTI]

    Guo, Ting

    THREAT CALL PROCEDURES BOMB THREAT CHECKLIST Date: Time: Time Caller Phone Number Where Hung Up: Call Received:Most bomb threats are received by phone. Bomb threats are serious until proven otherwise. Act threat is received by phone: 1. Remain calm. Keep the caller on the line for as long as possible. DO

  4. On the Eddington limit in accretion discs

    E-Print Network [OSTI]

    D. Heinzeller; W. J. Duschl

    2006-10-25T23:59:59.000Z

    Although the Eddington limit has originally been derived for stars, recently its relevance for the evolution of accretion discs has been realized. We discuss the question whether the classical Eddington limit - which has been applied globally for almost all calculations on accretion discs - is a good approximation if applied locally in the disc. For this purpose, a critical accretion rate corresponding to this type of modified classical Eddington limit is calculated from thin alpha-disc models and slim disc models. We account for the non-spherical symmetry of the disc models by computing the local upper limits on the accretion rate from vertical and radial force equilibria separately. It is shown that the results can differ considerably from the classical (global) value: The vertical radiation force limits the maximum accretion rate in the inner disc region to much less than the classical Eddington value in thin alpha-discs, while it allows for significantly higher accretion rates in slim discs. We discuss the implications of these results for the evolution of accretion discs and their central objects.

  5. Accretion Discs with Strong Toroidal Magnetic Fields

    E-Print Network [OSTI]

    M. C. Begelman; J. E. Pringle

    2006-12-12T23:59:59.000Z

    Simulations and analytic arguments suggest that the turbulence driven by magnetorotational instability (MRI) in accretion discs can amplify the toroidal (azimuthal) component of the magnetic field to a point at which magnetic pressure exceeds the combined gas + radiation pressure in the disc. Arguing from the recent analysis by Pessah and Psaltis, and other MRI results in the literature, we conjecture that the limiting field strength for a thin disc is such that the Alfven speed roughly equals the geometric mean of the Keplerian speed and the gas sound speed. We examine the properties of such magnetically-dominated discs, and show that they resolve a number of outstanding problems in accretion disc theory. The discs would be thicker than standard (Shakura-Sunyaev) discs at the same radius and accretion rate, and would tend to have higher colour temperatures. If they transport angular momentum according to an alpha-prescription, they would be stable against the thermal and viscous instabilities that are found in standard disc models. In discs fuelling active galactic nuclei, magnetic pressure support could also alleviate the restriction on accretion rate imposed by disc self-gravity.

  6. Accretion and plasma outflow from dissipationless discs

    E-Print Network [OSTI]

    Sergei Bogovalov; Stanislav Kelner

    2008-09-02T23:59:59.000Z

    We consider an extreme case of disc accretion onto a gravitating centre when the viscosity in the disc is negligible. The angular momentum and the rotational energy of the accreted matter is carried out by a magnetized wind outflowing from the disc. The outflow of matter from the disc occurs due to the Blandford & Payne(1982) centrifugal mechanism. The disc is assumed to be cold. Accretion and outflow are connected by the conservation of the energy, mass and the angular momentum. The basic properties of the outflow, angular momentum flux and energy flux per particle in the wind, do not depend on the details of the structure of the accretion disc. In the case of selfsimilar accretion/outflow, the dependence of the rate of accretion $\\dot M$ in the disc depends on the disc radius $r$ on the law $\\dot M \\sim r^{{1\\over2(\\alpha^2-1)}}$, where $\\alpha$ is a dimensionless Alfvenic radius. In the case of $\\alpha \\gg 1$, the accretion in the disc is provided by very weak matter outflow from the disc and the outflow predominantly occurs from the very central part of the disc. The solution obtained in the work provides mechanism which transforms the gravitational energy of the accreted matter into the energy of the outflowing wind with efficiency close to 100%. The final velocity can essentially exceed Kepler velocity at the site of the wind launch. This mechanism allows us to understand the nature of the astrophysical objects with low luminosity discs and energetic jet-like outflows.

  7. The Roles of Discs for Planetary Systems

    E-Print Network [OSTI]

    Li-Chin Yeh; Ing-Guey Jiang

    2007-01-29T23:59:59.000Z

    It is known that the discs are detected for some of the extra-solar planetary systems. It is also likely that there was a disc mixing with planets and small bodies while our Solar System was forming. From our recent results, we conclude that the discs play two roles: the gravity makes planetary systems more chaotic and the drag makes planetary systems more resonant.

  8. HD 98800: A most unusual debris disc

    E-Print Network [OSTI]

    P. E. Verrier; N. W. Evans

    2008-07-31T23:59:59.000Z

    The dynamics of planetesimals in the circumbinary debris disc of the quadruple star system HD 98800 are investigated. Evolving a spherical shell of test particles from a million years ago to the present day indicates that both coplanar and retrograde warped discs could exist, as well as a high inclination halo of material. Significant gaps are seen in the discs, as well as unexpected regions of stability due to the retrograde nature of the stellar orbits. Despite a viewing angle almost perpendicular to the direction of the warp of the planetesimal disc it is still intersected by the line of sight for eccentricities of the outer orbit of 0.5 or less.

  9. accretion disc 2d: Topics by E-print Network

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

    of a dwarf novae disc through its outburst cycle, from isolating the spectrum of a disc wind to revealing the geometry of disc spiral shocks. I end with an outline of the future...

  10. accretion discs ii: Topics by E-print Network

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

    of a dwarf novae disc through its outburst cycle, from isolating the spectrum of a disc wind to revealing the geometry of disc spiral shocks. I end with an outline of the future...

  11. accretion disc origin: Topics by E-print Network

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

    of a dwarf novae disc through its outburst cycle, from isolating the spectrum of a disc wind to revealing the geometry of disc spiral shocks. I end with an outline of the future...

  12. accretion disc viewed: Topics by E-print Network

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

    of a dwarf novae disc through its outburst cycle, from isolating the spectrum of a disc wind to revealing the geometry of disc spiral shocks. I end with an outline of the future...

  13. accretion disc structure: Topics by E-print Network

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

    of a dwarf novae disc through its outburst cycle, from isolating the spectrum of a disc wind to revealing the geometry of disc spiral shocks. I end with an outline of the future...

  14. Accelerated planetesimal growth in self-gravitating protoplanetary discs

    E-Print Network [OSTI]

    Rice, William K; Lodato, G; Pringle, J E; Armitage, P J; Bonnell, I A

    2004-01-01T23:59:59.000Z

    self-gravitating protoplanetary discs W. K. M. Rice, 1 † G.in marginally stable, self-gravitating protoplanetary discs.The drag force between the disc gas and the em- bedded

  15. Spectral energy distributions of selfgravitating QSO discs

    E-Print Network [OSTI]

    Edwin Sirko; Jeremy Goodman

    2002-09-23T23:59:59.000Z

    We calculate spectral energy distributions (SEDs) of steady accretion discs at high accretion rates, as appropriate for bright QSOs, under the assumption that the outer parts are heated sufficiently to maintain marginal gravitational stability, presumably by massive stars formed within the disc. The SED is independent of the nature of these auxiliary sources if their inputs are completely thermalized. Standard assumptions are made for angular momentum transport, with an alpha parameter less than unity. With these prescriptions, the luminosity of the disc is sensitive to its opacity, in contrast to standard discs powered by release of orbital energy alone. Compared to the latter, our discs have a broader SED, with a second peak in the near-infrared that is energetically comparable to the blue bump. The energy in the second peak increases with the outer radius of the disc, provided that the accretion rate is constant with radius. By comparing our computed SEDs with observed ones, we limit the outer radius of the disc to be less than 10^5 Schwarzschild radii, or about one parsec, in a typical QSO. We also discuss some properties of our minimum-Q discs in the regions where auxiliary heating is dominant (10^3-10^5 Schwarzschild radii).

  16. The tidal disruption of protoplanetary accretion discs

    E-Print Network [OSTI]

    John D. Larwood

    1997-05-30T23:59:59.000Z

    In this paper we revisit the problem of the tidal interaction occuring between a protostellar accretion disc and a secondary point mass following a parabolic trajectory. We model the disc response analytically and we compare our results with three-dimensional SPH simulations. Inviscid as well as viscous hydrodynamics is considered. We show that in a viscous system the response derived from inviscid considerations is predominant even for the highest estimates of an anomalous disc shear viscosity. The angular momentum lost from the disc during the encounter is derived from linear theory, for distant fly-bys, as well as the changes to the disc orientation expected in non-coplanar encounters. It is shown that the target discs can become warped and precess by a small amount during non-coplanar encounters. This small precession is shown to give rise to a relative tilt of the disc which is always more important for determining its final orientation than is the change to the orbital inclination. We discuss the implications of our results for protostellar accretion discs and planetary systems.

  17. artificial disc replacement: Topics by E-print Network

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

    in three-dimensional discs CERN Preprints Summary: Vortex formation through the Rossby wave instability (RWI) in protoplanetary discs has been invoked to play a role in planet...

  18. artificial cervical disc: Topics by E-print Network

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

    in three-dimensional discs CERN Preprints Summary: Vortex formation through the Rossby wave instability (RWI) in protoplanetary discs has been invoked to play a role in planet...

  19. artificial disc arthroplasty: Topics by E-print Network

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

    in three-dimensional discs CERN Preprints Summary: Vortex formation through the Rossby wave instability (RWI) in protoplanetary discs has been invoked to play a role in planet...

  20. BOMB THREAT CALL PROCEDURES

    E-Print Network [OSTI]

    Boyce, Richard L.

    BOMB THREAT CALL PROCEDURES WHO TO CONTACT (select one) · Follow your local guidelines · Federal Protective Service (FPS) Police 1-877-4-FPS-411 (1-877-437-7411) · 911 Most bomb threats are received by phone. Bomb threats are serious until proven otherwise. Act quickly, but remain calm and obtain

  1. Structure and kinematics of edge-on galaxy discs -- V. The dynamics of the stellar discs

    E-Print Network [OSTI]

    M. Kregel; P. C. van der Kruit; K. C. Freeman

    2005-01-24T23:59:59.000Z

    In earlier papers in this series we determined the intrinsic stellar disc kinematics of fifteen intermediate to late type edge-on spiral galaxies using a dynamical modeling technique. From the photometry we find that intrinsically more flattened discs tend to have a lower face-on central surface brightness and a larger dynamica mass-to-light ratio. This observation suggests that at a constant maximum rotational velocity lower surface brightness discs have smaller vertical stellar velocity dispersions.Although the individual uncertainties are large, we find from the dynamical modeling that at least twelve discs are submaximal. The average disc contributes 53$\\pm$4 percent to the observed rotation at 2.2 disc scalelengths, with a 1$\\sigma$ scatter of 15 percent. This percentage becomes somewhat lower when effects of finite disc flattening and gravity by the dark halo and the gas are taken into account. Since boxy and peanut-shaped bulges are probably associated with bars, the result suggests that at 2.2$h_{\\rm R}$ the submaximal nature of discs is independent of barredness. The possibility remains that very high surface brightness discs are maximal.We confirm that the radial stellar disc velocity dispersion is related to the galaxy maximum rotational velocity. The scatter in this $\\sigma-v_{\\rm max}$ relation appears to correlate with the disc flattening, face-on central surface brightness and dynamical mass-to-light ratio. Low surface brightness discs tend to be more flattened and have smaller stellar velocity dispersions. The findings are consistent with the observed correlation between disc flattening and dynamical mass-to-light ratio.

  2. Gravitationally coupled scale-free discs

    E-Print Network [OSTI]

    Yue Shen; Yu-Qing Lou

    2004-06-16T23:59:59.000Z

    In a composite fluid system of two gravitationally coupled barotropic scale-free discs bearing a rotation curve $v\\propto r^{-\\beta}$ and a power-law surface mass density $\\Sigma_0\\propto r^{-\\alpha}$ with $\\alpha=1+2\\beta$, we construct coplanar stationary aligned and spiral perturbation configurations in the two discs. Due to the mutual gravitational interaction, there are two independent classes of perturbation modes with surface mass density disturbances in the two coupled discs being either in-phase or out-of-phase. We derive analytical criteria for such perturbation modes to exist and show numerical examples. We compute the aligned and spiral perturbation modes systematically to explore the entire parameter regime. For the axisymmetric $m=0$ case with radial oscillations, there are two unstable regimes of ring-fragmentation and collapse corresponding to short and long radial wavelengths, respectively. Only within a certain range of the rotation parameter $D_s^2$ (square of the effective Mach number for the stellar disc), can a composite disc system be stable against all axisymmetric perturbations. Compared with a single-disc system, the coupled two-disc system becomes less stable against such axisymmetric instabilities.

  3. Three-dimensional SPH simulations of accretion discs

    E-Print Network [OSTI]

    Henri M. J. Boffin; Kei Haraguchi; Takuya Matsuda

    1998-12-01T23:59:59.000Z

    We discuss some 3D numerical simulations of accretion discs using the SPH method and a polytropic equation of state. We show that discs exist even for as large value of the polytropic index as 1.2, and that these discs are always in hydrostatic balance. We also show that even without any inflow, spiral shocks appear in the discs.

  4. SSRL Call for Proposals

    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:Energy: Grid Integration Redefining What's PossibleRadiation Protection245C Unlimited ReleaseWelcome ton n u aOct. 29, 2012 Nov.1-4 Nov.Call

  5. How to play a disc brake

    E-Print Network [OSTI]

    Oleg N. Kirillov

    2007-08-22T23:59:59.000Z

    We consider a gyroscopic system under the action of small dissipative and non-conservative positional forces, which has its origin in the models of rotating bodies of revolution being in frictional contact. The spectrum of the unperturbed gyroscopic system forms a "spectral mesh" in the plane "frequency -gyroscopic parameter" with double semi-simple purely imaginary eigenvalues at zero value of the gyroscopic parameter. It is shown that dissipative forces lead to the splitting of the semi-simple eigenvalue with the creation of the so-called "bubble of instability" - a ring in the three-dimensional space of the gyroscopic parameter and real and imaginary parts of eigenvalues, which corresponds to complex eigenvalues. In case of full dissipation with a positive-definite damping matrix the eigenvalues of the ring have negative real parts making the bubble a latent source of instability because it can "emerge" to the region of eigenvalues with positive real parts due to action of both indefinite damping and non-conservative positional forces. In the paper, the instability mechanism is analytically described with the use of the perturbation theory of multiple eigenvalues. As an example stability of a rotating circular string constrained by a stationary load system is studied in detail. The theory developed seems to give a first clear explanation of the mechanism of self-excited vibrations in the rotating structures in frictional contact, that is responsible for such well-known phenomena of acoustics of friction as the squealing disc brake and the singing wine glass.

  6. Variability of black hole accretion discs: The cool, thermal disc component

    E-Print Network [OSTI]

    M. Mayer; J. E. Pringle

    2006-01-29T23:59:59.000Z

    We extend the model of King et al. (2004) for variability in black hole accretion discs, by taking proper account of the thermal properties of the disc. Because the degree of variability in the King et al. (2004) model depends sensitively on the ratio of disc thickness to radius, H/R, it is important to follow the time-dependence of the local disc structure as the variability proceeds. In common with previous authors, we develop a one-zone model for the local disc structure. We agree that radial heat advection plays an important role in determining the inner disc structure, and also find limit-cycle behaviour. When the stochastic magnetic dynamo model of King et al. (2004) is added to these models, we find similar variability behaviour to before. We are now better placed to put physical constraints on model parameters. In particular, we find that in order to be consistent with the low degree of variability seen in the thermal disc component of black hole binaries, we need to limit the energy density of the poloidal field that can be produced by local dynamo cells in the disc to less than a few percent of the energy density of the dynamo field within the disc itself.

  7. Planet formation in self-gravitating discs 

    E-Print Network [OSTI]

    Gibbons, Peter George

    2013-11-28T23:59:59.000Z

    The work performed here studies particle dynamics in local two-dimensional simulations of self-gravitating accretion discs with a simple cooling law. It is well known that the structure which arises in the gaseous component ...

  8. Particle Acceleration in (by) Accretion Discs

    E-Print Network [OSTI]

    J. I. Katz

    1992-05-04T23:59:59.000Z

    I present a model for acceleration of protons by the second-order Fermi process acting on randomly scrambled magnetic flux arches above an accretion disc. The accelerated protons collide with thermal protons in the disc, producing degraded energetic protons, charged and neutral pions, and neutrons. The pions produce gamma-rays by spontaneous decay of $\\pi^0$ and by bremsstrahlung and Compton processes following the decay of $\\pi^\\pm$ to $e^\\pm$.

  9. Photoevaporation of protoplanetary discs I: hydrodynamic models

    E-Print Network [OSTI]

    R. D. Alexander; C. J. Clarke; J. E. Pringle

    2006-03-09T23:59:59.000Z

    In this paper we consider the effect of the direct ionizing stellar radiation field on the evolution of protoplanetary discs subject to photoevaporative winds. We suggest that models which combine viscous evolution with photoevaporation of the disc (e.g. Clarke, Gendrin & Sotomayor 2001) incorrectly neglect the direct field after the inner disc has drained, at late times in the evolution. We construct models of the photoevaporative wind produced by the direct field, first using simple analytic arguments and later using detailed numerical hydrodynamics. We find that the wind produced by the direct field at late times is much larger than has previously been assumed, and we show that the mass-loss rate scales as $R_{in}^{1/2}$ (where $R_{in}$ is the radius of the instantaneous inner disc edge). We suggest that this result has important consequences for theories of disc evolution, and go on to consider the effects of this result on disc evolution in detail in a companion paper (Alexander, Clarke & Pringle 2006b).

  10. Turbulent drag reduction through oscillating discs

    E-Print Network [OSTI]

    Wise, Daniel J

    2014-01-01T23:59:59.000Z

    The changes of a turbulent channel flow subjected to oscillations of wall flush-mounted rigid discs are studied by means of direct numerical simulations. The Reynolds number is $R_\\tau$=$180$, based on the friction velocity of the stationary-wall case and the half channel height. The primary effect of the wall forcing is the sustained reduction of wall-shear stress, which reaches a maximum of 20%. A parametric study on the disc diameter, maximum tip velocity, and oscillation period is presented, with the aim to identify the optimal parameters which guarantee maximum drag reduction and maximum net energy saving, computed by taking into account the power spent to actuate the discs. This may be positive and reaches 6%. The Rosenblat viscous pump flow is used to predict the power spent for disc motion in the turbulent channel flow and to estimate localized and transient regions over the disc surface subjected to the turbulent regenerative braking effect, for which the wall turbulence exerts work on the discs. The...

  11. The Disc-Jet Connection

    E-Print Network [OSTI]

    Ralph E. Pudritz; Robi Banerjee

    2005-07-11T23:59:59.000Z

    A large body of theoretical and computational work shows that jets - modelled as magnetized disk winds - exert an external torque on their underlying disks that can efficiently remove angular momentum and act as major drivers of disk accretion. These predictions have recently been confirmed in direct HST measurements of the jet rotation and angular momentum transport in low mass protostellar systems. We review the theory of disc winds and show that their physics is universal and scales to jets from both low and high mass star forming regions. This explains the observed properties of outflows in massive star forming regions, before the central massive star generates an ultracompact HII region. We also discuss the recent numerical studies on the formation of massive accretion disks and outflows through gravitational collapse, including our own work on 3D Adaptive Mesh simulations (using the FLASH code) of the hydromagnetic collapse of an initial rotating, and cooling Bonner-Ebert sphere. Magnetized collapse gives rise to outflows. Our own simulations show that both a jet-like disk wind on sub AU scales, and a larger scale molecular outflow occur (Banerjee and Pudritz 2005).

  12. Slug pellet spreading: the double-disc performances available with a single disc spreader

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    1 Slug pellet spreading: the double-disc performances available with a single disc spreader D for slug pellets application. The principal aim of this paper is to show the chosen way to reach spreading pellets 1 Introduction In France, slugs are considered as a harmful destroyer for crops. Their activities

  13. The Evolution of Stellar Exponential Discs

    E-Print Network [OSTI]

    Annette Ferguson; Cathie Clarke

    2001-03-14T23:59:59.000Z

    Models of disc galaxies which invoke viscosity-driven radial flows have long been known to provide a natural explanation for the origin of stellar exponential discs, under the assumption that the star formation and viscous timescales are comparable. We present models which invoke simultaneous star formation, viscous redistribution of gas and cosmologically-motivated gaseous infall and explore the predictions such models make for the scale length evolution and radial star formation history of galactic stellar discs. While the inclusion of viscous flows is essential for ensuring that the stellar disc is always exponential over a significant range in radius, we find that such flows play essentially no role in determining the evolution of the disc scale length. In models in which the main infall phase precedes the onset of star formation and viscous evolution, we find the exponential scale length to be rather invariant with time. On the other hand, models in which star formation/viscous evolution and infall occur concurrently result in a smoothly increasing scale length with time, reflecting the mean angular momentum of material which has fallen in at any given epoch. The disc stellar populations in these models are predominantly young (ie. ages < 5 Gyr) beyond a few scale lengths. In both cases, viscous flows are entirely responsible for transporting material to very large radii. We discuss existing observational constraints on these models from studies of both local and moderate redshift disc galaxies. In particular, a good agreement is found between the solar neighbourhood star formation history predicted by our infall model and the recent observational determination of this quantity by Rocha-Pinto et al (2000).

  14. Exact General Relativistic Discs and the Advance of Perihelion

    E-Print Network [OSTI]

    D. Vogt; P. S. Letelier

    2008-05-20T23:59:59.000Z

    The advance of perihelion for geodesic motion on the galactic plane of some exact general relativistic disc solutions is calculated. Approximate analytical and numerical results are presented for the static Chazy-Curzon and the Schwarzschild discs in Weyl coordinates, the Schwarzschid disc in isotropic coordinantes and the stationary Kerr disc in the Weyl-Lewis-Papapetrou metrics. It is found that for these disc models the advance of perihelion may be an increasing or decreasing function of the orbital excentricity. The precession due to Newtonian gravity for these disc models is also calculated.

  15. PublicSafety Phone Calls

    E-Print Network [OSTI]

    person could be encour- aging to the caller. 10.Report Harassing Calls to Your Telephone Company to file a report. Place Ads with Caution. Don't ex- tend the call trying to figure out who is calling does not need to know your name and/or num- ber. Purchase an Answering Machine. As we all know

  16. Using a Bull Call Spread 

    E-Print Network [OSTI]

    Bevers, Stan; Amosson, Stephen H.; Waller, Mark L.; Dhuyvetter, Kevin C.

    2008-10-07T23:59:59.000Z

    The Bull Call Spread can be used to hedge against or to benefit from a rising market. The user buys a call option at a particular strike price and sells a call option at a higher strike price. Margin requirements, advantages and disadvantages...

  17. Satellites in Discs: Regulating the Accretion Luminosity

    E-Print Network [OSTI]

    Dave Syer; Cathie Clarke

    1995-05-04T23:59:59.000Z

    We demonstrate, using a simple analytic model, that the presence of a massive satellite can globally modify the structure and emission properties of an accretion disc to which it is tidally coupled. We show, using two levels of numerical approximation, that the analytic model gives reasonable results. The results are applicable to two astrophysical situations. In the case of an active galactic nucleus, we consider the case of a $\\sim 10^3\\Msun$ compact companion to the central black-hole and show that it could modulate the emitted spectrum on a timescale of $\\sim10^5$ years. In the case of a T Tauri accretion disc, a satellite such as a sub-dwarf or giant planet could modify the disc spectral energy distribution over a substantial fraction of the T Tauri star lifetime.

  18. Appearance of Keplerian discs orbiting Kerr superspinars

    E-Print Network [OSTI]

    Zdenek Stuchlik; Jan Schee

    2011-01-19T23:59:59.000Z

    We study optical phenomena related to appearance of Keplerian accretion discs orbiting Kerr superspinars predicted by the string theory. The superspinar exterior is described by the standard Kerr naked singularity geometry breaking the black hole limit on the internal angular momentum (spin). We construct local photon escape cones for a variety of orbiting sources that enable to determine the superspinars silhouette in the case of distant observers. We show that the superspinar silhouette depends strongly on the assumed edge where the external Kerr spacetime is joined to the internal spacetime governed by the string theory and significantly differs from the black hole silhouette. The appearance of the accretion disc is strongly dependent on the value of the superspinar spin in both their shape and frequency shift profile. Apparent extension of the disc grows significantly with growing spin, while the frequency shift grows with descending spin. This behavior differs substantially from appearance of discs orbiting black holes enabling thus, at least in principle, to distinguish clearly the Kerr superspinars and black holes. In vicinity of a Kerr superspinar the non-escaped photons have to be separated to those captured by the superspinar and those being trapped in its strong gravitational field leading to self-illumination of the disc that could even influence its structure and causes self-reflection effect of radiation of the disc. The amount of trapped photons grows with descending of the superspinar spin. We thus can expect significant self-illumination effects in the field of Kerr superspinars with near-extreme spin $a \\sim 1$.

  19. The runaway instability of thick discs around black holes. II. Non constant angular momentum discs

    E-Print Network [OSTI]

    Frederic Daigne; Jose A. Font

    2003-11-28T23:59:59.000Z

    We present results from a comprehensive number of relativistic, time-dependent, axisymmetric simulations of the runaway instability of non-constant angular momentum thick discs around black holes. This second paper extends earlier results where only constant angular momentum discs were considered. All relevant aspects of the theory of stationary thick discs around rotating black holes, necessary to build the initial state in our simulations, are presented in great detail. The angular momentum of the discs is assumed to increase outwards with the radial distance according to a power law. The main simplifying assumptions of our approach are not to include magnetic fields and self-gravity in the discs. Furthermore, the dynamics of the spacetime is accounted for by computing the transfer of mass and angular momentum from the disc to the black hole through the event horizon : the evolution of the central black hole is assumed to follow a sequence of Kerr black holes of increasing mass and spin. In agreement with previous results based on stationary models we find that by allowing the mass and the spin of the black hole to grow, constant angular momentum discs rapidly become unstable on a dynamical timescale. The comparison with the results of paper I shows that the effect of the angular momentum transfer from the torus to the black hole is to make constant angular momentum discs less unstable, increasing the timescale of the instability. However, we find that non-constant angular momentum discs are dramatically stabilized for very small values of the angular momentum slope. Our time-dependent simulations confirm, thus, the predictions of stationary studies concerning the stabilizing effect of non-constant angular momentum distributions.

  20. Disc valve for sampling erosive process streams

    DOE Patents [OSTI]

    Mrochek, J.E.; Dinsmore, S.R.; Chandler, E.W.

    1986-01-07T23:59:59.000Z

    A four-port disc valve is described for sampling erosive, high temperature process streams. A rotatable disc defining opposed first and second sampling cavities rotates between fired faceplates defining flow passageways positioned to be alternatively in axial alignment with the first and second cavities. Silicon carbide inserts and liners composed of [alpha] silicon carbide are provided in the faceplates and in the sampling cavities to limit erosion while providing lubricity for a smooth and precise operation when used under harsh process conditions. 1 fig.

  1. Hard Discs on the Hyperbolic Plane

    E-Print Network [OSTI]

    Carl D. Modes; Randall D. Kamien

    2007-11-30T23:59:59.000Z

    We examine a simple hard disc fluid with no long range interactions on the two dimensional space of constant negative Gaussian curvature, the hyperbolic plane. This geometry provides a natural mechanism by which global crystalline order is frustrated, allowing us to construct a tractable model of disordered monodisperse hard discs. We extend free area theory and the virial expansion to this regime, deriving the equation of state for the system, and compare its predictions with simulation near an isostatic packing in the curved space.

  2. accretion disc radii: Topics by E-print Network

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

    the hole. Such a break in the disc may be significant in systems where we know the inclination of the outer accretion disc to the line of sight, such as some X-ray binaries: the...

  3. accretion discs due: Topics by E-print Network

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

    the hole. Such a break in the disc may be significant in systems where we know the inclination of the outer accretion disc to the line of sight, such as some X-ray binaries: the...

  4. accretion discs formed: Topics by E-print Network

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

    the hole. Such a break in the disc may be significant in systems where we know the inclination of the outer accretion disc to the line of sight, such as some X-ray binaries: the...

  5. accretion discs induced: Topics by E-print Network

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

    and the rotational energy of the accreted matter is carried out by a magnetized wind outflowing from the disc. The outflow of matter from the disc occurs due to the...

  6. accretion disc particle: Topics by E-print Network

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

    the hole. Such a break in the disc may be significant in systems where we know the inclination of the outer accretion disc to the line of sight, such as some X-ray binaries: the...

  7. accretion disc dynamo: Topics by E-print Network

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

    the hole. Such a break in the disc may be significant in systems where we know the inclination of the outer accretion disc to the line of sight, such as some X-ray binaries: the...

  8. accretion disc boundary: Topics by E-print Network

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

    the hole. Such a break in the disc may be significant in systems where we know the inclination of the outer accretion disc to the line of sight, such as some X-ray binaries: the...

  9. Demographics of Transition Discs in Ophiuchus and Taurus

    E-Print Network [OSTI]

    Najita, Joan R; Muzerolle, James

    2015-01-01T23:59:59.000Z

    Transition disc systems are young stars that appear to be on the verge of dispersing their protoplanetary discs. We explore the nature of these systems by comparing the stellar accretion rates and disc masses of transition discs and normal T Tauri stars in Taurus and Ophiuchus. After controlling for the known dependencies of stellar accretion rate and disc mass and on age, stellar accretion rate on stellar mass, and disc mass on the presence of stellar or sub-stellar companions, we find that the normal T Tauri stars show a trend of stellar accretion rate increasing with disc mass. The transition discs tend to have higher average disc masses than normal T Tauri stars as well as lower accretion rates than normal T Tauri stars of the same disc mass. These results are most consistent with the interpretation that the transition discs have formed objects massive enough to alter the accretion flow, i.e., single or multiple giant planets. Several Ophiuchus T Tauri stars that are not known transition disc systems also...

  10. DISC1–ATF4 transcriptional repression complex: dual regulation of the cAMP-PDE4 cascade by DISC1

    E-Print Network [OSTI]

    Ishizuka, K

    Disrupted-In-Schizophrenia 1 (DISC1), a risk factor for major mental illnesses, has been studied extensively in the context of neurodevelopment. However, the role of DISC1 in neuronal signaling, particularly in conjunction ...

  11. Disc valve for sampling erosive process streams

    DOE Patents [OSTI]

    Mrochek, J.E.; Dinsmore, S.R.; Chandler, E.W.

    1984-08-16T23:59:59.000Z

    This is a patent for a disc-type, four-port sampling valve for service with erosive high temperature process streams. Inserts and liners of ..cap alpha..-silicon carbide respectively, in the faceplates and in the sampling cavities, limit erosion while providing lubricity for a smooth and precise operation. 1 fig.

  12. BBEE Public Utility Conference Call

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

    BBEE Public Utility Conference Call May 19, 2011 - Summary Summer Goodwin, BPA, welcomed public utility representative participants, asked them to introduce themselves, and...

  13. Counterrotating perfect fluid discs as sources of electrovacuum static spacetimes

    E-Print Network [OSTI]

    Gonzalo García-Reyes; Guillermo A. González

    2008-10-14T23:59:59.000Z

    The interpretation of some electrovacuum spacetimes in terms of counterrotating perfect fluid discs is presented. The interpretation is mades by means of an "inverse problem" approach used to obtain disc sources of known static solutions of the Einstein-Maxwell equations. In order to do such interpretation, a detailed study is presented of the counterrotating model (CRM) for generic electrovacuum static axially symmetric relativistic thin discs with nonzero radial pressure. Four simple families of models of counterrotating charged discs based on Chazy-Curzon-type, Zipoy-Voorhees-type, Bonnor-Sackfield-type, and charged and magnetized Darmois electrovacuum metrics are considered where we obtain some discs with a CRM well behaved.

  14. Tilted accretion discs in cataclysmic variables: tidal instabilities and superhumps

    E-Print Network [OSTI]

    J. R. Murray; P. J. Armitage

    1998-09-10T23:59:59.000Z

    We investigate the growth of tidal instabilities in accretion discs in a binary star potential, using three dimensional numerical simulations. As expected from analytic work, the disc is prone to an eccentric instability provided that it is large enough to extend to the 3:1 resonance. The eccentric disc leads to positive superhumps in the light curve. It has been proposed that negative superhumps might arise from a tilted disc, but we find no evidence that the companion gravitational tilt instability can grow fast enough in a fluid disc to create a measurable inclination. The origin of negative superhumps in the light curves of cataclysmic variables remains a puzzle.

  15. Broad reprocessed Balmer emission from warped accretion discs

    E-Print Network [OSTI]

    Sheng-Miao Wu; Ting-Gui Wang; Xiao-Bo Dong

    2008-07-11T23:59:59.000Z

    Double peaked broad emission lines in active galactic nuclei are generally considered to be formed in an accretion disc. In this paper, we compute the profiles of reprocessing emission lines from a relativistic, warped accretion disc around a black hole in order to explore the possibility that certain asymmetries in the double-peaked emission line profile which can not be explained by a circular Keplerian disc may be induced by disc warping. The disc warping also provides a solution for the energy budget in the emission line region because it increases the solid angle of the outer disc portion subtended to the inner portion of the disc. We adopted a parametrized disc geometry and a central point-like source of ionizing radiation to capture the main characteristics of the emission line profile from such discs. We find that the ratio between the blue and red peaks of the line profiles becoming less than unity can be naturally predicted by a twisted warped disc, and a third peak can be produced in some cases. We show that disc warping can reproduce the main features of multi-peaked line profiles of four active galactic nuclei from the Sloan Digital Sky Survey.

  16. Accretion Disc Evolution in Single and Binary T Tauri Stars

    E-Print Network [OSTI]

    Philip J. Armitage; C. J. Clarke; C. A. Tout

    1998-10-30T23:59:59.000Z

    We present theoretical models for the evolution of T Tauri stars surrounded by circumstellar discs. The models include the effects of pre-main-sequence stellar and time dependent disc evolution, and incorporate the effects of stellar magnetic fields acting on the inner disc. For single stars, consistency with observations in Taurus-Auriga demands that disc dispersal occurs rapidly, on much less than the viscous timescale of the disc, at roughly the epoch when heating by stellar radiation first dominates over internal viscous dissipation. Applying the models to close binaries, we find that because the initial conditions for discs in binaries are uncertain, studies of extreme mass ratio systems are required to provide a stringent test of theoretical disc evolution models. We also note that no correlation of the infra-red colours of T Tauri stars with their rotation rate is observed, in apparent contradiction to the predictions of simple magnetospheric accretion models.

  17. Virial theorem for radiating accretion discs

    E-Print Network [OSTI]

    Patryk Mach

    2012-04-18T23:59:59.000Z

    A continuum version of the virial theorem is derived for a radiating self-gravitating accretion disc around a compact object. The central object is point-like, but we can avoid the regularization of its gravitational potential. This is achieved by applying a modified Pohozaev-Rellich identity to the gravitational potential of the disk only. The theorem holds for general stationary configurations, including discontinuous flows (shock waves, contact discontinuities). It is used to test numerical solutions of a model of self-gravitating radiative accretion discs. The presented virial theorem should be useful in the analysis of those (possibly radiating) hydrodynamical systems in astrophysics where the central mass and the mass of the fluid are comparable and none of them can be neglected.

  18. Astrometric signatures of self-gravitating protoplanetary discs

    E-Print Network [OSTI]

    W. K. M. Rice; P. J. Armitage; M. R. Bate; I. A. Bonnell

    2002-09-09T23:59:59.000Z

    We use high resolution numerical simulations to study whether gravitational instabilities within circumstellar discs can produce astrometrically detectable motion of the central star. For discs with masses of M_disc = 0.1 M_star, which are permanantly stable against fragmentation, we find that the magnitude of the astrometric signal depends upon the efficiency of disc cooling. Short cooling times produce prominent filamentary spiral structures in the disc, and lead to stellar motions that are potentially observable with future high precision astrometric experiments. For a disc that is marginally unstable within radii of \\~10 au, we estimate astrometric displacements of 10-100 microarcsec on decade timescales for a star at a distance of 100 pc. The predicted displacement is suppressed by a factor of several in more stable discs in which the cooling time exceeds the local dynamical time by an order of magnitude. We find that the largest contribution comes from material in the outer regions of the disc and hence, in the most pessimistic scenario, the stellar motions caused by the disc could confuse astrometric searches for low mass planets orbiting at large radii. They are, however, unlikely to present any complications in searches for embedded planets orbiting at small radii, relative to the disc size, or Jupiter mass planets or greater orbiting at large radii.

  19. Dispersal of Gaseous Circumstellar Discs around High-Mass Stars

    E-Print Network [OSTI]

    Yue Shen; Yu-Qing Lou

    2006-05-19T23:59:59.000Z

    We study the dispersal of a gaseous disc surrounding a central high-mass stellar core once this circumstellar disc becomes fully ionized. If the stellar and surrounding EUV and X-ray radiations are so strong as to rapidly heat up and ionize the entire circumstellar disc as further facilitated by disc magnetohydrodynamic (MHD) turbulence, a shock can be driven to travel outward in the fully ionized disc, behind which the disc expands and thins. For an extremely massive and powerful stellar core, the ionized gas pressure overwhelms the centrifugal and gravitational forces in the disc. In this limit, we construct self-similar shock solutions for such an expansion and depletion phase. As a significant amount of circumstellar gas being removed, the relic disc becomes vulnerable to strong stellar winds and fragments into clumps. We speculate that disc disappearance happens rapidly, perhaps on a timescale of $\\sim 10^3-10^4\\hbox{yr}$ once the disc becomes entirely ionized sometime after the onset of thermal nuclear burning in a high-mass stellar core.

  20. Mass Flow and Accretion through gaps in Accretion Discs

    E-Print Network [OSTI]

    Willy Kley

    1998-09-21T23:59:59.000Z

    We study the structure and dynamics of the gap created by a protoplanet in an accretion disc. The hydrodynamic equations for a flat, two-dimensional, non-selfgravitating protostellar accretion disc with an embedded, Jupiter sized protoplanet on a circular orbit are solved. To simulate possible accretion of mass onto the protoplanet we continually remove mass from the interior of the planet's Roche lobe which is monitored. Firstly, it is shown that consistent results independent on numerical issues (such as boundary or initial conditions, artificial viscosity or resolution) can be obtained. Then, a detailed parameter study delineates the influence of the disc viscosity and pressure on the magnitude of the accretion rate. We find that, even after the formation of a gap in the disc, the planet is still able to accrete more mass from the disc. This accretion occurs from regions of the disc which are radially exterior and interior to the planet's orbital radius. The rate depends on the magnitude of the viscosity and vertical thickness of the disc. For a disc viscosity alpha=10^{-3} and vertical thickness H/r=0.05 we estimate the time scale for the accumulation of one Jupiter mass to be of order hundred thousand years. For a larger(smaller) viscosity and disc thickness this accretion rate is increasing(decreasing). For a very small viscosity (alpha disc.

  1. Accretion disc viscosity: a limit on the anisotropy

    E-Print Network [OSTI]

    Nixon, Chris

    2015-01-01T23:59:59.000Z

    Observations of warped discs can give insight into the nature of angular momentum transport in accretion discs. Only a few objects are known to show strong periodicity on long timescales, but when such periodicity is present it is often attributed to precession of the accretion disc. The X-ray binary Hercules X-1/HZ Herculis (Her X-1) is one of the best examples of such periodicity and has been linked to disc precession since it was first observed. By using the current best-fitting models to Her X-1, which invoke precession driven by radiation warping, I place a constraint on the effective viscosities that act in a warped disc. These effective viscosities almost certainly arise due to turbulence induced by the magneto-rotational instability. The constraints derived here are in agreement with analytical and numerical investigations into the nature of magneto-hydrodynamic disc turbulence, but at odds with some recent global simulations.

  2. [NeII] emission line profiles from photoevaporative disc winds

    E-Print Network [OSTI]

    R. D. Alexander

    2008-09-01T23:59:59.000Z

    I model profiles of the [NeII] forbidden emission line at 12.81um, emitted by photoevaporative winds from discs around young, solar-mass stars. The predicted line luminosities (~ 1E-6 Lsun) are consistent with recent data, and the line profiles vary significantly with disc inclination. Edge-on discs show broad (30-40km/s) double-peaked profiles, due to the rotation of the disc, while in face-on discs the structure of the wind results in a narrower line (~10km/s) and a significant blue-shift (5-10km/s). These results suggest that observations of [NeII] line profiles can provide a direct test of models of protoplanetary disc photoevaporation.

  3. Using a Bull Call Spread

    E-Print Network [OSTI]

    Bevers, Stan; Amosson, Stephen H.; Waller, Mark L.; Dhuyvetter, Kevin C.

    2008-10-07T23:59:59.000Z

    .20 call option and receives a premium of $0.44 ($2,200 per 5,000-bushel contract). His net cost to imple- ment the strategy (excluding commissions) is $1.43 or $7,150 per contract. This is demonstrated in Table 2. Table 1. March KCBT call option... premiums. Strike price Premium $9.70 $1.87 $10.20 $1.38 $10.50 $0.88 $11.20 $0.74 $11.50 $0.59 $12.20 $0.44 Table 2. Costs to implement strategy. Action Income/ expense ($/bushel) Income/ expense (Total $) Buy KCBT March $9.70 call option -$1.87 -$9...

  4. On the observability of spiral structures in CV accretion discs

    E-Print Network [OSTI]

    Danny Steeghs; Rudolf Stehle

    1999-02-25T23:59:59.000Z

    We use the grid of hydrodynamic accretion disc calculations of Stehle (1999) to construct orbital phase dependent emission line profiles of thin discs carrying spiral density waves. The observational signatures of spiral waves are explored to establish the feasibility of detecting spiral waves in cataclysmic variable discs using prominent emission lines in the visible range of the spectrum. For high Mach number accretion discs (M = 15-30), we find that the spiral shock arms are so tightly wound that they leave few obvious fingerprints in the emission lines. Only a minor variation of the double peak separation in the line profile at a level of 8% is produced. For accretion discs in outburst (M = 5-20) however, the lines are dominated by the emission from an m=2 spiral pattern in the disc. We show that reliable Doppler tomograms of spiral shock patterns can be reconstructed provided that a signal to noise of at least 15, a wavelength resolution of 80 km/s and a time resolution of 50 spectra per binary orbit is achieved. We confirm that the observed spiral pattern in the disc of IP Pegasi can be reproduced by tidal density waves in the accretion disc and demands the presence of a large, hot disc, at least in the early outburst stages.

  5. Three-integral models for axisymmetric galactic discs

    E-Print Network [OSTI]

    B. Famaey; K. Van Caelenberg; H. Dejonghe

    2002-05-21T23:59:59.000Z

    We present new equilibrium component distribution functions that depend on three analytic integrals in a Stackel potential, and that can be used to model stellar discs of galaxies. These components are generalizations of two-integral ones and can thus provide thin discs in the two-integral approximation. Their most important properties are the partly analytical expression for their moments, the disc-like features of their configuration space densities (exponential decline in the galactic plane and finite extent in the vertical direction) and the anisotropy of their velocity dispersions. We further show that a linear combination of such components can fit a van der Kruit disc.

  6. Analysis of rabbit intervertebral disc physiology based on water metabolism. II. Changes in normal intervertebral discs under axial vibratory load

    SciTech Connect (OSTI)

    Hirano, N.; Tsuji, H.; Ohshima, H.; Kitano, S.; Itoh, T.; Sano, A.

    1988-11-01T23:59:59.000Z

    Metabolic changes induced by axial vibratory load to the spine were investigated based on water metabolism in normal intervertebral discs of rabbits with or without pentobarbital anesthesia. Tritiated water concentration in the intervertebral discs of unanesthetized rabbits was reduced remarkably by axial vibration for 30 minutes using the vibration machine developed for this study. Repeated vibratory load for 18 and 42 hours duration showed the recovery of /sup 3/H/sub 2/O concentration of the intervertebral disc without anesthesia. Computer simulation suggested a reduction of blood flow surrounding the intervertebral disc following the vibration stress. However, no reduction of the /sup 3/H/sub 2/O concentration in the intervertebral disc was noted under anesthesia. Emotional stress cannot be excluded as a factor in water metabolism in the intervertebral disc.

  7. Call for Papers Web Graphics

    E-Print Network [OSTI]

    Lau, W. H. Nynson

    Call for Papers Web Graphics Special Issue of IEEE Computer Graphics & Applications Guest Editors a migration of traditional applications to run on the Web environment and a growing demand for more powerful web-based applications. Fused by the increasing availability and dramatic reduction in the cost of 3D

  8. 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved.

    E-Print Network [OSTI]

    Zhang, Meirong

    © 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. #12;© 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. #12;© 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. #12;© 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved

  9. 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved.

    E-Print Network [OSTI]

    Qian, Weihong

    © 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. #12;© 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. #12;© 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. #12;© 1995-2004 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved

  10. 1995-2006 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. 1995-2006 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved.

    E-Print Network [OSTI]

    Zhang, Ke-Min

    © 1995-2006 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. #12;© 1995-2006 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. #12;© 1995-2006 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved. #12;© 1995-2006 Tsinghua Tongfang Optical Disc Co., Ltd. All rights reserved

  11. Far-infrared and sub-millimetre surveys of circumstellar discs

    E-Print Network [OSTI]

    Phillips, Neil Matthew

    2011-06-27T23:59:59.000Z

    . This thesis focuses on observational studies at far-infrared and sub-millimetre wavelengths of debris discs and the late stages of protoplanetary disc evolution. An overview of surveys for debris discs performed to date is presented, highlighting...

  12. accretion discs non-barotropic: Topics by E-print Network

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

    of a dwarf novae disc through its outburst cycle, from isolating the spectrum of a disc wind to revealing the geometry of disc spiral shocks. I end with an outline of the future...

  13. DISC1 & GSK3? modulate PDE4 activity: functional integration of psychiatric associated signalling pathways 

    E-Print Network [OSTI]

    Carlyle, Becky Catherine

    2010-01-01T23:59:59.000Z

    Following the discovery of the DISC1 gene in 2000, subsequent research has led to DISC1 becoming one of the most promising candidate genes for psychiatric disorders. Acting as a scaffold protein, DISC1 has a large number ...

  14. Discs Large Homolog 1: Identifying Molecular Mechanisms that Guide Functional Specificity in Lymphocytes

    E-Print Network [OSTI]

    Crocetti, Jillian Ann

    2014-01-01T23:59:59.000Z

    homolog of the Drosophila discs-large tumor suppressor. EMBOHumphries, L.A. & Miceli, M.C. Discs Large Homolog 1 (Dlg1)C. Shaw, W. Swat, B. Seed, Discs large (Dlg1) complexes in

  15. Self-regulated gravitational accretion in protostellar discs

    E-Print Network [OSTI]

    E. I. Vorobyov; S. Basu

    2007-09-13T23:59:59.000Z

    We present a numerical model for the evolution of a protostellar disc that has formed self-consistently from the collapse of a molecular cloud core. The global evolution of the disc is followed for several million years after its formation. The capture of a wide range of spatial and temporal scales is made possible by use of the thin-disc approximation. We focus on the role of gravitational torques in transporting mass inward and angular momentum outward during different evolutionary phases of a protostellar disc with disc-to-star mass ratio of order 0.1. In the early phase, when the infall of matter from the surrounding envelope is substantial, mass is transported inward by the gravitational torques from spiral arms that are a manifestation of the envelope-induced gravitational instability in the disc. In the late phase, when the gas reservoir of the envelope is depleted, the distinct spiral structure is replaced by ongoing irregular nonaxisymmetric density perturbations. The amplitude of these density perturbations decreases with time, though this process is moderated by swing amplification aided by the existence of the disc's sharp outer edge. Our global modelling of the protostellar disc reveals that there is typically a residual nonzero gravitational torque from these density perturbations, i.e. their effects do not exactly cancel out in each region. In particular, the net gravitational torque in the inner disc tends to be negative during first several million years of the evolution, while the outer disc has a net positive gravitational torque. Our global model of a self-consistently formed disc shows that it is also self-regulated in the late phase, so that it is near the Toomre stability limit, with a near-uniform Toomre parameter Q\\approx 1.5-2.0. (Abstract abridged).

  16. Call title: ENERGY -EU India Call Call identifier: FP7-ENERGY-2010-INDIA

    E-Print Network [OSTI]

    Milano-Bicocca, Università

    Collaborative ProjectAREA ENERGY.2.1: PHOTOVOLTAICS ENERGY.2010.2.1-3: Development of new concentrator modules and field performance evaluation of Concentrated PV systems - EU-India Call Collaborative Project AREA will be constituted if there is a sufficient number of good quality proposals. It will be used if extra budget becomes

  17. Secular evolution of viscous and self-gravitating circumstellar discs

    E-Print Network [OSTI]

    E. I. Vorobyov; Shantanu Basu

    2008-12-06T23:59:59.000Z

    We add the effect of turbulent viscosity via the \\alpha-prescription to models of the self-consistent formation and evolution of protostellar discs. Our models are non-axisymmetric and carried out using the thin-disc approximation. Self-gravity plays an important role in the early evolution of a disc, and the later evolution is determined by the relative importance of gravitational and viscous torques. In the absence of viscous torques, a protostellar disc evolves into a self-regulated state with disk-averaged Toomre parameter Q \\sim 1.5-2.0, non-axisymmetric structure diminishing with time, and maximum disc-to-star mass ratio \\xi = 0.14. We estimate an effective viscosity parameter \\alpha_eff associated with gravitational torques at the inner boundary of our simulation to be in the range 10^{-4}-10^{-3} during the late evolution. Addition of viscous torques with a low value \\alpha = 10^{-4} has little effect on the evolution, structure, and accretion properties of the disc, and the self-regulated state is largely preserved. A sequence of increasing values of \\alpha results in the discs becoming more axisymmetric in structure, being more gravitationally stable, having greater accretion rates, larger sizes, shorter lifetimes, and lower disc-to-star mass ratios. For \\alpha=10^{-2}, the model is viscous-dominated and the self-regulated state largely disappears by late times. (Abridged)

  18. Giant Planet Migration in Viscous Power-Law Discs

    E-Print Network [OSTI]

    R. G. Edgar

    2007-04-03T23:59:59.000Z

    Many extra-solar planets discovered over the past decade are gas giants in tight orbits around their host stars. Due to the difficulties of forming these `hot Jupiters' in situ, they are generally assumed to have migrated to their present orbits through interactions with their nascent discs. In this paper, we present a systematic study of giant planet migration in power law discs. We find that the planetary migration rate is proportional to the disc surface density. This is inconsistent with the assumption that the migration rate is simply the viscous drift speed of the disc. However, this result can be obtained by balancing the angular momentum of the planet with the viscous torque in the disc. We have verified that this result is not affected by adjusting the resolution of the grid, the smoothing length used, or the time at which the planet is released to migrate.

  19. EM SSAB Chairs Conference Call

    Office of Environmental Management (EM)

    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 1112011 Strategic Plan Department ofNotices |Notice of38:3:1:EM OfficialAugust 27,Conference Call

  20. Special Science Call Projects Announced | EMSL

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

    Special Science Call Projects Announced Special Science Call Projects Announced Released: April 22, 2015 23 high-impact research proposals accepted EMSL Scientist Zihua Zhu...

  1. Photoevaporation of protoplanetary discs II: evolutionary models and observable properties

    E-Print Network [OSTI]

    R. D. Alexander; C. J. Clarke; J. E. Pringle

    2006-03-09T23:59:59.000Z

    We present a new model for protoplanetary disc evolution. This model combines viscous evolution with photoevaporation of the disc, in a manner similar to Clarke, Gendrin & Sotomayor (2001). However in a companion paper (Alexander, Clarke & Pringle 2006a) we have shown that at late times such models must consider the effect of stellar radiation directly incident on the inner disc edge, and here we model the observational implications of this process. We find that the entire disc is dispersed on a time-scale of order $10^5$yr after a disc lifetime of a few Myr, consistent with observations of T Tauri (TT) stars. We use a simple prescription to model the spectral energy distribution of the evolving disc, and demonstrate that the model is consistent with observational data across a wide range of wavelengths. We note also that the model predicts a short ``inner hole'' phase in the evolution of all TT discs, and make predictions for future observations at mid-infrared and millimetre wavelengths.

  2. Does the stellar disc flattening depend on the galaxy type?

    E-Print Network [OSTI]

    Mosenkov, A V; Reshetnikov, V P; Bizyaev, D V; Kautsch, S J

    2015-01-01T23:59:59.000Z

    We analyze the dependence of the stellar disc flatness on the galaxy morphological type using 2D decomposition of galaxies from the reliable subsample of the Edge-on Galaxies in SDSS (EGIS) catalogue. Combining these data with the retrieved models of the edge-on galaxies from the Two Micron All Sky Survey (2MASS) and the Spitzer Survey of Stellar Structure in Galaxies (S$^4$G) catalogue, we make the following conclusions: (1) The disc relative thickness $z_0/h$ in the near- and mid-infrared passbands correlates weakly with morphological type and does not correlate with the bulge-to-total luminosity ratio $B/T$ in all studied bands. (2) Applying an 1D photometric profile analysis overestimates the disc thickness in galaxies with large bulges making an illusion of the relationship between the disc flattening and the ratio $B/T$. (3) In our sample the early-type disc galaxies (S0/a) have both flat and "puffed" discs. The early spirals and intermediate-type galaxies have a large scatter of the disc flatness, whic...

  3. Lindblad resonance torques in relativistic discs: I. Basic equations

    E-Print Network [OSTI]

    Christopher M. Hirata

    2011-03-01T23:59:59.000Z

    Lindblad resonances have been suggested as an important mechanism for angular momentum transport and heating in discs in binary black hole systems. We present the basic equations for the torque and heating rate for relativistic thin discs subjected to a perturbation. The Lindblad resonance torque is written explicitly in terms of metric perturbations for an equatorial disc in a general axisymmetric, time-stationary spacetime with a plane of symmetry. We show that the resulting torque formula is gauge-invariant. Computations for the Schwarzschild and Kerr spacetimes are presented in the companion paper.

  4. Finance Peer Exchange Kickoff Call | Department of Energy

    Energy Savers [EERE]

    Finance Peer Exchange Kickoff Call Finance Peer Exchange Kickoff Call BetterBuildings Financing Peer Exchange Kickoff Call, Call Slides and Discussion Summary, April 28, 2011. Call...

  5. Dynamic Bayesian networks for the classification of spinning discs

    E-Print Network [OSTI]

    Schmidt, Aurora Clare, 1981-

    2004-01-01T23:59:59.000Z

    This thesis considers issues for the application of particle filters to a class of nonlinear filtering and classification problems. Specifically, we study a prototype system of spinning discs. The system combines linear ...

  6. The structure of protoplanetary discs around evolving young stars

    E-Print Network [OSTI]

    Bitsch, Bertram; Lambrechts, Michiel; Morbidelli, Alessandro

    2014-01-01T23:59:59.000Z

    The formation of planets with gaseous envelopes takes place in protoplanetary accretion discs on time-scales of several millions of years. Small dust particles stick to each other to form pebbles, pebbles concentrate in the turbulent flow to form planetesimals and planetary embryos and grow to planets, which undergo substantial radial migration. All these processes are influenced by the underlying structure of the protoplanetary disc, specifically the profiles of temperature, gas scale height and density. The commonly used disc structure of the Minimum Mass Solar Nebular (MMSN) is a simple power law in all these quantities. However, protoplanetary disc models with both viscous and stellar heating show several bumps and dips in temperature, scale height and density caused by transitions in opacity, which are missing in the MMSN model. These play an important role in the formation of planets, as they can act as sweet spots for the formation of planetesimals via the streaming instability and affect the direction...

  7. Spiral density waves in the outer galactic gaseous discs

    E-Print Network [OSTI]

    Khoperskov, S A

    2015-01-01T23:59:59.000Z

    Deep HI observations of the outer parts of disc galaxies demonstrate the frequent presence of extended, well-developed spiral arms far beyond the optical radius. To understand the nature and the origin of such outer spiral structure, we investigate the propagation in the outer gaseous disc of large-scale spiral waves excited in the bright optical disc. Using hydrodynamical simulations, we show that non-axisymmetric density waves, penetrating in the gas through the outer Lindblad resonance, can exhibit relatively regular spiral structures outside the bright optical stellar disc. For low-amplitude structures, the results of numerical simulations match the predictions of a simple WKB linear theory. The amplitude of spiral structure increases rapidly with radius. Beyond $\\approx 2$ optical radii, spirals become nonlinear (the linear theory becomes quantitatively and qualitatively inadequate) and unstable to Kelvin-Helmholtz instability. In numerical simulations, in models for which gas is available very far out, ...

  8. accretion disc plasmas: Topics by E-print Network

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

    should give insight into the magnetic dynamics of accretion discs and jets. A high-speed multiple-frame CCD camera reveals images of the formation and helical instability of a...

  9. accretion disc theory: Topics by E-print Network

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

    we conjecture that the limiting field strength for a thin disc is such that the Alfven speed roughly equals the geometric mean of the Keplerian speed and the gas sound speed. We...

  10. accretion disc models: Topics by E-print Network

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

    we conjecture that the limiting field strength for a thin disc is such that the Alfven speed roughly equals the geometric mean of the Keplerian speed and the gas sound speed. We...

  11. accretion disc model: Topics by E-print Network

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

    we conjecture that the limiting field strength for a thin disc is such that the Alfven speed roughly equals the geometric mean of the Keplerian speed and the gas sound speed. We...

  12. attenuating disc wind: Topics by E-print Network

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

    point located at (x,z)(0,-d) and (ii) streamlines that emerge at a constant inclination angle from the disc midplane (the x-axis, as we consider geometrically thin...

  13. Noncommutative Field Theory: Numerical Analysis with the Fuzzy Disc

    E-Print Network [OSTI]

    Fedele Lizzi; Bernardino Spisso

    2012-07-28T23:59:59.000Z

    The fuzzy disc is a discretization of the algebra of functions on the two dimensional disc using finite matrices which preserves the action of the rotation group. We define a $\\varphi^4$ scalar field theory on it and analyze numerically for three different limits for the rank of the matrix going to infinity. The numerical simulations reveal three different phases: uniform and disordered phases already the present in the commutative scalar field theory and a nonuniform ordered phase as a noncommutative effects. We have computed the transition curves between phases and their scaling. This is in agreement with studies on the fuzzy sphere, although the speed of convergence for the disc seems to be better. We have performed also three the limits for the theory in the cases of the theory going to the commutative plane or commutative disc. In this case the theory behaves differently, showing the intimate relationship between the nonuniform phase and noncommutative geometry.

  14. The precession of eccentric discs in close binaries

    E-Print Network [OSTI]

    James R. Murray

    1999-11-25T23:59:59.000Z

    We consider the precession rates of eccentric discs in close binaries, and compare theoretical predictions with the results of numerical disc simulations and with observed superhump periods. A simple dynamical model for precession is found to be inadequate. For mass ratios less than approximately 1/4 a linear dynamical model does provide an upper limit for disc precession rates. Theory suggests that pressure forces have a significant retrograde impact upon the precession rate (Lubow 1992). We find that the disc precession rates for three systems with accurately known mass ratios are significantly slower than predicted by the dynamical theory, and we attribute the difference to pressure forces. By assuming that pressure forces of similar magnitude occur in all superhumping systems, we obtain an improved fit to superhump observations.

  15. The instantaneous radial growth rate of stellar discs

    E-Print Network [OSTI]

    Pezzulli, Gabriele; Boissier, Samuel; Muñoz-Mateos, Juan Carlos

    2015-01-01T23:59:59.000Z

    We present a new and simple method to measure the instantaneous mass and radial growth rates of the stellar discs of spiral galaxies, based on their star formation rate surface density (SFRD) profiles. Under the hypothesis that discs are exponential with time-varying scalelengths, we derive a universal theoretical profile for the SFRD, with a linear dependence on two parameters: the specific mass growth rate $\

  16. Electromagnetic counterparts from counter-rotating relativistic kicked discs

    E-Print Network [OSTI]

    Olindo Zanotti

    2011-08-23T23:59:59.000Z

    We show the results of two dimensional general relativistic inviscid and isothermal hydrodynamical simulations comparing the behavior of co-rotating (with respect to the black hole rotation) and counter-rotating circumbinary quasi-Keplerian discs in the post merger phase of a supermassive binary black hole system. While confirming the spiral shock generation within the disc due to the combined effects of mass loss and recoil velocity of the black hole, we find that the maximum luminosity of counter-rotating discs is a factor ~(2-12) higher than in the co-rotating case, depending on the spin of the black hole. On the other hand, the luminosity peak happens ~10 days later with respect to the co-rotating case, for a binary with a total mass M~10^6 M_\\odot. Although the global dynamics of counter-rotating discs in the post merger phase of a merging event is very similar to that for co-rotating discs, an important difference has been found. In fact, increasing the spin of the central black hole produces more luminous co-rotating discs while less luminous counter-rotating ones.

  17. Wakes of ram pressure stripped disc galaxies

    E-Print Network [OSTI]

    Roediger, E; Hoeft, M

    2006-01-01T23:59:59.000Z

    Spiral galaxies that move through the intracluster medium lose a substantial amount of their gas discs due to ram pressure stripping. The recent observations of NGC 4388 by Oosterloo & van Gorkom 2005 reveal a tail of stripped gas of ~ 100 kpc behind the source galaxy. We present first 3D hydrodynamical simulations of the evolution of such ram pressure stripped tails. We find that if the ICM wind does not vary significantly over a period of a few 100 Myr, subsonic galaxies produce a tail with regular features similar to a von-Karman vortex street. In this case, the tail widens systematically by about 45 kpc per 100 kpc distance behind the source galaxy. The widening rate is independent of the galaxy's inclination for a large range of inclinations. For supersonic galaxies, the tail is more irregular than for subsonic ones. The tail observed for NGC 4388 is narrower than the tails in our simulations. Reasons for this difference may be additional physical processes such as heat conduction or viscosity. In ad...

  18. Wakes of ram pressure stripped disc galaxies

    E-Print Network [OSTI]

    E. Roediger; M. Brueggen; M. Hoeft

    2006-03-21T23:59:59.000Z

    Spiral galaxies that move through the intracluster medium lose a substantial amount of their gas discs due to ram pressure stripping. The recent observations of NGC 4388 by Oosterloo & van Gorkom 2005 reveal a tail of stripped gas of ~ 100 kpc behind the source galaxy. We present first 3D hydrodynamical simulations of the evolution of such ram pressure stripped tails. We find that if the ICM wind does not vary significantly over a period of a few 100 Myr, subsonic galaxies produce a tail with regular features similar to a von-Karman vortex street. In this case, the tail widens systematically by about 45 kpc per 100 kpc distance behind the source galaxy. The widening rate is independent of the galaxy's inclination for a large range of inclinations. For supersonic galaxies, the tail is more irregular than for subsonic ones. The tail observed for NGC 4388 is narrower than the tails in our simulations. Reasons for this difference may be additional physical processes such as heat conduction or viscosity. In addition, we conclude that the observed S-shape of this tail is not due to von Karman oscillations, because this galaxy is likely to move supersonically. A reason for the observed shape may be motions in the ambient ICM. Finally, we discuss implications for the distribution of metals in the ICM due to ram pressure stipping.

  19. Restoration of disc height through non-invasive spinal decompression is associated with decreased discogenic low back pain: a retrospective cohort study

    E-Print Network [OSTI]

    2010-01-01T23:59:59.000Z

    in reduction of lumbar disc prolapse by traction. Arch Physeffect of traction on lumbar disc herniations. Spine 1989,Innervation of "painful" lumbar discs. Spine 1997, 22:2342-

  20. Nuclear stellar discs in early-type galaxies --- II. Photometric properties

    E-Print Network [OSTI]

    Cecilia Scorza; Frank C. van den Bosch

    1998-06-04T23:59:59.000Z

    Hubble Space Telescope images of two early-type galaxies harboring both nuclear and outer stellar discs are studied in detail. By means of a photometric decomposition, the images of NGC 4342 and NGC 4570 are analyzed and the photometric properties of the nuclear discs investigated. We find a continuity of properties in the parameter space defined by the central surface brightness and the scalelength of discs in spirals, S0s and embedded discs in ellipticals, in the sense that the nuclear discs extend the observed disc properties even further towards smaller scalelengths and brighter central surface brightnesses. When including the nuclear discs, disc properties span more than four orders of magnitude in both scalelength and central surface brightness. The nuclear discs studied here are the smallest and brightest stellar discs known, and as such, they are as extreme in their photometric properties as Malin I, when compared to typical galactic discs that obey Freeman's law. We discuss a possible formation scenario in which the double-disc structure observed in these galaxies has been shaped by now dissolved bars. Based on the fact that the black holes known to exist in some of these galaxies have masses comparable to those of the nuclear discs, we explore a possible link between the black holes and the nuclear discs.

  1. Call Identifier: CIP-IEE-2009

    E-Print Network [OSTI]

    De Cindio, Fiorella

    ://ec.europa.eu/intelligentenergy #12;Intelligent Energy ­ Europe Call for Proposals 2009 2/17 CALL FOR PROPOSALS 2009 FOR ACTIONS UNDER THE PROGRAMME "INTELLIGENT ENERGY ­ EUROPE" Call Identifier: CIP-IEE-2009 TABLE OF CONTENTS 1. THE INTELLIGENT ENERGY ­ EUROPE PROGRAMME 3 2. BUDGET, FUNDING RATES AND ELIGIBILITY OF COSTS 5 3. ELIGIBILITY CRITERIA 5

  2. Oscillations of Thick Accretion Discs Around Black Holes - II

    E-Print Network [OSTI]

    Eduardo Rubio-Herrera; William H. Lee

    2005-05-21T23:59:59.000Z

    We present a numerical study of the global modes of oscillation of thick accretion discs around black holes. We have previously studied the case of constant distributions of specific angular momentum. In this second paper, we investigate (i) how the size of the disc affects the oscillation eigenfrequencies, and (ii) the effect of power-law distributions of angular momentum on the oscillations. In particular, we compare the oscillations of the disc with the epicyclic eigenfrequencies of a test particle with different angular momentum distributions orbiting around the central object. We find that there is a frequency shift away from the epicyclic eigenfrequency of the test particle to lower values as the size of the tori is increased. We have also studied the response of a thick accretion disc to a localized external perturbation using non constant specific angular momentum distributions within the disc. We find that in this case it is also possible (as reported previously for constant angular momentum distributions) to efficiently excite internal modes of oscillation. In fact we show here that the local perturbations excite global oscillations (acoustic p modes) closely related to the epicyclic oscillations of test particles. Our results are particularly relevant in the context of low mass X-ray binaries and microquasars, and the high frequency Quasi-Periodic Oscillations (QPOs) observed in them. Our computations make use of a Smooth Particle Hydrodynamics (SPH) code in azimuthal symmetry, and use a gravitational potential that mimics the effects of strong gravity.

  3. Silicate features in Galactic and extragalactic post-AGB discs

    E-Print Network [OSTI]

    Gielen, C; Van Winckel, H; Evans, T Lloyd; Woods, P M; Kemper, F; Marengo, M; Meixner, M; Sloan, G C; Tielens, A G G M

    2011-01-01T23:59:59.000Z

    Aims. In this paper we study the Spitzer and TIMMI2 infrared spectra of post-AGB disc sources, both in the Galaxy and the LMC. Using the observed infrared spectra we determine the mineralogy and dust parameters of the discs, and look for possible differences between the Galactic and extragalactic sources. Methods. Modelling the full spectral range observed allows us to determine the dust species present in the disc and different physical parameters such as grain sizes, dust abundance ratios, and the dust and continuum temperatures. Results. We find that all the discs are dominated by emission features of crystalline and amorphous silicate dust. Only a few sample sources show features due to CO2 gas or carbonaceous molecules such as PAHs and C60 fullerenes. Our analysis shows that dust grain processing in these discs is strong, resulting in large average grain sizes and a very high crystallinity fraction. However, we do not find any correlations between the derived dust parameters and properties of the central...

  4. Black hole mergers: do gas discs lead to spin alignment?

    E-Print Network [OSTI]

    Giuseppe Lodato; Davide Gerosa

    2012-11-01T23:59:59.000Z

    In this Letter we revisit arguments suggesting that the Bardeen-Petterson effect can coalign the spins of a central supermassive black hole binary accreting from a circumbinary (or circumnuclear) gas disc. We improve on previous estimates by adding the dependence on system parameters, and noting that the nonlinear nature of warp propagation in a thin viscous disc affects alignment. This reduces the disc's ability to communicate the warp, and can severely reduce the effectiveness of disc-assisted spin alignment. We test our predictions with a Monte Carlo realization of random misalignments and accretion rates and we find that the outcome depends strongly on the spin magnitude. We estimate a generous upper limit to the probability of alignment by making assumptions which favour it throughout. Even with these assumptions, about 40% of black holes with $a \\gtrsim 0.5$ do not have time to align with the disc. If the residual misalignment is not small and it is maintained down to the final coalescence phase this can give a powerful recoil velocity to the merged hole. Highly spinning black holes are thus more likely of being subject to strong recoils, the occurrence of which is currently debated.

  5. Tip sheet: Expanded Library of Congress Call Number Classification system Call Number Subject Matter

    E-Print Network [OSTI]

    Kambhampati, Patanjali

    Tip sheet: Expanded Library of Congress Call Number Classification system Call Number Subject R: Medicine T: Technology U: Military Science Z: Bibliography. Library Science. Information

  6. MEDIA BRIEFING CONFERENCE CALL: Secretary Chu to Host Solar Energy...

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

    BRIEFING CONFERENCE CALL: Secretary Chu to Host Solar Energy Conference Call MEDIA BRIEFING CONFERENCE CALL: Secretary Chu to Host Solar Energy Conference Call February 4, 2011 -...

  7. Dispersion in the lifetime and accretion rate of T Tauri discs

    E-Print Network [OSTI]

    Philip J. Armitage; Cathie J. Clarke; Francesco Palla

    2003-03-14T23:59:59.000Z

    We compare evolutionary models for protoplanetary discs that include disc winds with observational determinations of the disc lifetime and accretion rate in Taurus. Using updated estimates for stellar ages in Taurus, together with published classifications, we show that the evolution of the disc fraction with stellar age is similar to that derived for ensembles of stars within young clusters. Around 30 percent of stars lose their discs within 1 Myr, while the remainder have disc lifetimes that are typically in the 1-10 Myr range. We show that the latter range of ages is consistent with theoretical models for disc evolution, provided that there is a dispersion of around 0.5 in the log of the initial disc mass. The same range of initial conditions brackets the observed variation in the accretion rate of Classical T Tauri stars at a given age. We discuss the expected lifetime of discs in close binary systems, and show that our models predict that the disc lifetime is almost constant for separations exceeding 10 au. This implies a low predicted fraction of binaries that pair a Classical T Tauri star with a Weak-lined T Tauri star, and is in better agreement with observations of the disc lifetime in binaries than disc models that do not include disc mass loss in a wind.

  8. Accretion Discs Around Black Holes: Developement of Theory

    E-Print Network [OSTI]

    G. S. Bisnovatyi-Kogan

    1999-11-11T23:59:59.000Z

    Standard accretion disk theory is formulated which is based on the local heat balance. The energy produced by a turbulent viscous heating is supposed to be emitted to the sides of the disc. Sources of turbulence in the accretion disc are connected with nonlinear hydrodynamic instability, convection, and magnetic field. In standard theory there are two branches of solution, optically thick, and optically thin. Advection in accretion disks is described by the differential equations what makes the theory nonlocal. Low-luminous optically thin accretion disc model with advection at some suggestions may become advectively dominated, carrying almost all the energy inside the black hole. The proper account of magnetic filed in the process of accretion limits the energy advected into a black hole, efficiency of accretion should exceed $\\sim 1/4$ of the standard accretion disk model efficiency.

  9. Constraints on AGN accretion disc viscosity derived from continuum variability

    E-Print Network [OSTI]

    Rhaana L. C. Starling; Aneta Siemiginowska; Phil Uttley; Roberto Soria

    2003-09-10T23:59:59.000Z

    We estimate a value of the viscosity parameter in AGN accretion discs for the PG quasar sample. We assume that optical variability on time-scales of months to years is caused by local instabilities in the inner accretion disc. Comparing the observed variability time-scales to the thermal time-scales of alpha-disc models we obtain constraints on the viscosity parameter for the sample. We find that, at a given L/L_Edd, the entire sample is consistent with a single value of the viscosity parameter, alpha. We obtain constraints of 0.01 < alpha < 0.03 for 0.01 < L/L_Edd < 1.0. This narrow range suggests that these AGN are all seen in a single state, with a correspondingly narrow spread of black hole masses or accretion rates. The value of alpha we derive is consistent with predictions by current simulation s in which MHD turbulence is the primary viscosity mechanism.

  10. Some challenges and directions for next generation accretion disc theory

    E-Print Network [OSTI]

    Blackman, Eric G

    2015-01-01T23:59:59.000Z

    Accretion disc theory is far less developed than that of stellar evolution, although a similarly mature phenomenological picture is ultimately desired. While conceptual progress from the interplay of theory and numerical simulations has amplified awareness of the role of magnetic fields in angular momentum transport, there remains a significant gap between the output of magneto-rotational instability (MRI) simulations and the synthesis of lessons learned into improved practical models. If discs are turbulent, then axisymmetric models must be recognized to be sensible only as mean field theories. Such is the case for the wonderfully practical and widely used framework of Shakura-Sunyaev (SS73). This model is most justifiable when the radial angular momentum transport dominates in discs and the transport is assumed to take the form of a local viscosity. However, the importance of large scale fields in coronae and jets and numerical evidence from MRI simulations points to a significant fraction of transport bein...

  11. Density waves in the shearing sheet III. Disc heating

    E-Print Network [OSTI]

    B. Fuchs

    2001-04-25T23:59:59.000Z

    The problem of dynamical heating of galactic discs by spiral density waves is discussed using the shearing sheet model. The secular evolution of the disc is described quantitatively by a diffusion equation for the distribution function of stars in the space spanned by integrals of motion of the stars, in particular the radial action integral and an integral related to the angular momentum. Specifically, disc heating by a succession of transient, `swing amplified' density waves is studied. It is shown that such density waves lead predominantly to diffusion of stars in radial action space. The stochastical changes of angular momenta of the stars and the corresponding stochastic changes of the guiding centre radii of the stellar orbits induced by this process are much smaller.

  12. Solution of the H3+ model on a disc

    E-Print Network [OSTI]

    Kazuo Hosomichi; Sylvain Ribault

    2007-01-17T23:59:59.000Z

    We determine all the correlators of the H3+ model on a disc with AdS2-brane boundary conditions in terms of correlators of Liouville theory on a disc with FZZT-brane boundary conditions. We argue that the Cardy-Lewellen constraints are weaker in the H3+ model than in rational conformal field theories due to extra singularities of the correlators, but strong enough to uniquely determine the bulk two-point function on a disc. We confirm our results by detailed analyses of the bulk-boundary two-point function and of the boundary two-point function. In particular we find that, although the target space symmetry preserved by AdS2-branes is the group SL(2,R), the open string states between two distinct parallel AdS2-branes belong to representations of the universal covering group.

  13. Dust trapping by spiral arms in gravitationally unstable protostellar discs

    E-Print Network [OSTI]

    Dipierro, Giovanni; Lodato, Giuseppe; Testi, Leonardo

    2015-01-01T23:59:59.000Z

    In this paper we discuss the influence of gravitational instabilities in massive protostellar discs on the dynamics of dust grains. Starting from a Smoothed Particle Hydrodynamics (SPH) simulation, we have computed the evolution of the dust in a quasi-static gas density structure typical of self-gravitating disc. For different grain size distributions we have investigated the capability of spiral arms to trap particles. We have run 3D radiative transfer simulations in order to construct maps of the expected emission at (sub-)millimetre and near-infrared wavelengths. Finally, we have simulated realistic observations of our disc models at (sub-)millimetre and near-infrared wavelengths as they may appear with the Atacama Large Millimetre/sub-millimetre Array (ALMA) and the High-Contrast Coronographic Imager for Adaptive Optics (HiCIAO) in order to investigate whether there are observational signatures of the spiral structure. We find that the pressure inhomogeites induced by gravitational instabilities produce a...

  14. 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).

  15. Is the Dark Disc contribution to Dark Matter Signals important ?

    E-Print Network [OSTI]

    Fu-Sin Ling

    2010-07-11T23:59:59.000Z

    Recent N-body simulations indicate that a thick disc of dark matter, co-rotating with the stellar disc, forms in a galactic halo after a merger at a redshift $zdisc component in the Milky Way could affect dramatically dark matter signals in direct and indirect detection. In this letter, we discuss the possible signal enhancement in connection with the characteristics of the local velocity distributions. We argue that the enhancement is rather mild, but some subtle effects may arise. In particular, the annual modulation observed by DAMA becomes less constrained by other direct detection experiments.

  16. Probing self-gravitating protostellar discs using smoothed particle hydrodynamics and radiative transfer 

    E-Print Network [OSTI]

    Forgan, Duncan Hugh

    2011-01-01T23:59:59.000Z

    Stars are likely to form with non-zero initial angular momentum, and will consequently possess a substantial gaseous protostellar disc in the early phases of their evolution. At this early stage, the disc mass is expected ...

  17. The effect of cooling on the global stability of self-gravitating protoplanetary discs

    E-Print Network [OSTI]

    W. K. M. Rice; P. J. Armitage; M. R. Bate; I. A. Bonnell

    2002-11-05T23:59:59.000Z

    Using a local model Gammie (2001) has shown that accretion discs with cooling times t_cool 3/Omega evolve into a quasi-steady state. We use three-dimensional smoothed particle hydrodynamic simulations of protoplanetary accretion discs to test if the local results hold globally. We find that for disc masses appropriate for T Tauri discs, the fragmentation boundary still occurs at a cooling time close to t_cool = 3/Omega. For more massive discs, which are likely to be present at an earlier stage of the star formation process, fragmentation occurs for longer cooling times, but still within a factor of two of that predicted using a local model. These results have implications not only for planet formation in protoplanetary discs and star formation in AGN discs, but also for the redistribution of angular momentum which could be driven by the presence of relatively massive objects within the accretion disc.

  18. EM SSAB Conference Calls- February 16, 2006

    Broader source: Energy.gov [DOE]

    Minutes and highlights of the Environmental Management (EM) Site Specific Advisory Board's (SSAB) Bi-Monthly conference call including Participants, DOE-HQ Representatives, Opening Remarks, Program...

  19. DOE Sustainability Reporting Open Line Help Call

    Broader source: Energy.gov [DOE]

    The Sustainability Performance Office (SPO) sponsors open line help calls to assist DOE sites and national laboratories with the annual sustainability reporting process. Representatives from the...

  20. EM SSAB Conference Calls- January 11, 2007

    Broader source: Energy.gov [DOE]

    Minutes and highlights of the Environmental Management (EM) Site Specific Advisory Board's (SSAB) Bi-Monthly conference call including Participants, DOE-HQ Representatives, Opening Remarks, Program...

  1. EM SSAB Conference Calls- November 9, 2006

    Broader source: Energy.gov [DOE]

    Minutes and highlights of the Environmental Management (EM) Site Specific Advisory Board's (SSAB) Bi-Monthly conference call including Participants, DOE-HQ Representatives, Opening Remarks, Program...

  2. EM SSAB Conference Calls- May 11, 2006

    Broader source: Energy.gov [DOE]

    Minutes and highlights of the Environmental Management (EM) Site Specific Advisory Board's (SSAB) Bi-Monthly conference call including Participants, DOE-HQ Representatives, Opening Remarks, Program...

  3. EM SSAB Conference Calls- December 15, 2005

    Broader source: Energy.gov [DOE]

    Minutes and highlights of the Environmental Management (EM) Site Specific Advisory Board's (SSAB) Bi-Monthly conference call including Participants, DOE-HQ Representatives, Opening Remarks, Program...

  4. Press Conference Call Tomorrow: Agriculture Secretary Vilsack...

    Office of Environmental Management (EM)

    Agriculture Secretary Vilsack and Energy Secretary Chu to Discuss Efforts to Reduce U.S. Oil Dependence Press Conference Call Tomorrow: Agriculture Secretary Vilsack and Energy...

  5. A correspondence between H3+ WZW and Liouville theories on discs

    E-Print Network [OSTI]

    Kazuo Hosomichi

    2007-01-29T23:59:59.000Z

    We discuss how the disc correlators of H3+ WZW model are determined in terms of those of Liouville theory.

  6. The Formation and Survival of Discs in a Lambda-CDM Universe

    E-Print Network [OSTI]

    Cecilia Scannapieco; Simon D. M. White; Volker Springel; Patricia B. Tissera

    2009-04-03T23:59:59.000Z

    We study the formation of galaxies in a Lambda-CDM Universe using high resolution hydrodynamical simulations with a multiphase treatment of gas, cooling and feedback, focusing on the formation of discs. Our simulations follow eight haloes similar in mass to the Milky Way and extracted from a large cosmological simulation without restriction on spin parameter or merger history. This allows us to investigate how the final properties of the simulated galaxies correlate with the formation histories of their haloes. We find that, at z = 0, none of our galaxies contain a disc with more than 20 per cent of its total stellar mass. Four of the eight galaxies nevertheless have well-formed disc components, three have dominant spheroids and very small discs, and one is a spheroidal galaxy with no disc at all. The z = 0 spheroids are made of old stars, while discs are younger and formed from the inside-out. Neither the existence of a disc at z = 0 nor the final disc-to-total mass ratio seems to depend on the spin parameter of the halo. Discs are formed in haloes with spin parameters as low as 0.01 and as high as 0.05; galaxies with little or no disc component span the same range in spin parameter. Except for one of the simulated galaxies, all have significant discs at z > ~2, regardless of their z = 0 morphologies. Major mergers and instabilities which arise when accreting cold gas is misaligned with the stellar disc trigger a transfer of mass from the discs to the spheroids. In some cases, discs are destroyed, while in others, they survive or reform. This suggests that the survival probability of discs depends on the particular formation history of each galaxy. A realistic Lambda-CDM model will clearly require weaker star formation at high redshift and later disc assembly than occurs in our models.

  7. Comparison of alternative methods for deriving hydraulic properties and scaling factors from single-disc tension

    E-Print Network [OSTI]

    Mohanty, Binayak P.

    Comparison of alternative methods for deriving hydraulic properties and scaling factors from single-disc] Analysis of single-disc tension infiltrometer data is commonly based on the interpretation of the steady and the time needed to wet the contact sand under the disc was successfully filtered from the raw data using

  8. A laboratory plasma experiment for studying magnetic dynamics of accretion discs and jets

    E-Print Network [OSTI]

    Hsu, Scott

    A laboratory plasma experiment for studying magnetic dynamics of accretion discs and jets S. C. Hsu into the magnetic dynamics of accretion discs and jets. A high-speed multiple-frame CCD camera reveals images of the formation and helical instability of a collimated plasma, similar to MHD models of disc jets, and also

  9. Feedback in simulations of disc-galaxy major mergers

    E-Print Network [OSTI]

    T. J. Cox; Patrik Jonsson; Joel R. Primack; Rachel S. Somerville

    2007-09-25T23:59:59.000Z

    Using hydrodynamic simulations of disc-galaxy major mergers, we investigate the star formation history and remnant properties when various parametrizations of a simple stellar feedback model are implemented. The simulations include radiative cooling, a density-dependent star formation recipe and a model for feedback from massive stars. The feedback model stores supernova feedback energy within individual gas particles and dissipates this energy on a time-scale specified by two free parameters; tau_fb, which sets the dissipative time-scale, and n, which sets the effective equation of state in star-forming regions. Using a self-consistent disc galaxy, modelled after a local Sbc spiral, in both isolated and major-merger simulations, we investigate parametrizations of the feedback model that are selected with respect to the quiescent disc stability. These models produce a range of star formation histories that are consistent with the star formation relation found by Kennicutt. All major mergers produce a population of new stars that is highly centrally concentrated, demonstrating a distinct break in the r1/4 surface density profile, consistent with previous findings. The half-mass radius and one-dimensional velocity dispersion are affected by the feedback model used. Finally, we compare our results to those of previous simulations of star formation in disc-galaxy major mergers, addressing the effects of star formation normalization, the version of smoothed particle hydrodynamics (SPH) employed and assumptions about the interstellar medium.

  10. NIHAO III: The constant disc gas mass conspiracy

    E-Print Network [OSTI]

    Stinson, G S; Wang, L; Macciò, A V; Herpich, J; Bradford, J D; Quinn, T R; Wadsley, J; Keller, B

    2015-01-01T23:59:59.000Z

    We show that the cool gas masses of galactic discs reach a steady state that lasts many Gyr after their last major merger in cosmological hydrodynamic simulations. The mass of disc gas, M$_{\\rm gas}$, depends upon a galaxy halo's spin and virial mass, but not upon stellar feedback. Halos with low spin have high star formation efficiency and lower disc gas mass. Similarly, lower stellar feedback leads to more star formation so the gas mass ends up nearly the same irregardless of stellar feedback strength. Even considering spin, the M$_{\\rm gas}$ relation with halo mass, M$_{200}$ only shows a factor of 3 scatter. The M$_{\\rm gas}$--M$_{200}$ relation show a break at M$_{200}$=$2\\times10^{11}$ M$_\\odot$ that corresponds to an observed break in the M$_{\\rm gas}$--M$_\\star$ relation. The constant disc mass stems from a shared halo gas density profile in all the simulated galaxies. In their outer regions, the profiles are isothermal. Where the profile rises above $n=10^{-3}$ cm$^{-3}$, the gas readily cools and th...

  11. A fast algorithm for random sequential adsorption of discs

    E-Print Network [OSTI]

    Jian-Sheng WANG

    1994-02-17T23:59:59.000Z

    An efficient algorithm for random sequential adsorption of hard discs in two dimensions is implemented. A precise value for the coverage is obtained: theta(infty) = 0.547069. The asymptotic law theta(t) = theta(infty) - ct^{-1/2} is verified to a high accuracy. Pair correlation function is analyzed.

  12. Solution of the Percus-Yevick equation for hard discs

    E-Print Network [OSTI]

    M. Adda-Bedia; E. Katzav; D. Vella

    2008-01-31T23:59:59.000Z

    We solve the Percus-Yevick equation in two dimensions by reducing it to a set of simple integral equations. We numerically obtain both the pair correlation function and the equation of state for a hard disc fluid and find good agreement with available Monte-Carlo calculations. The present method of resolution may be generalized to any even dimension.

  13. Jupiter and Super-Earth embedded in a gaseous disc

    E-Print Network [OSTI]

    E. Podlewska; E. Szuszkiewicz

    2007-12-19T23:59:59.000Z

    In this paper we investigate the evolution of a pair of interacting planets - a Jupiter mass planet and a Super-Earth with the 5.5 Earth masses - orbiting a Solar type star and embedded in a gaseous protoplanetary disc. We focus on the effects of type I and II orbital migrations, caused by the planet-disc interaction, leading to the Super-Earth capture in first order mean motion resonances by the Jupiter. The stability of the resulting resonant system in which the Super-Earth is on the internal orbit relatively to the Jupiter has been studied numerically by means of full 2D hydrodynamical simulations. Our main motivation is to determine the Super-Earth behaviour in the presence of the gas giant in the system. It has been found that the Jupiter captures the Super-Earth into the interior 3:2 or 4:3 mean motion resonances and the stability of such configurations depends on the initial planet positions and eccentricity evolution. If the initial separation of planet orbits is larger or close to that required for the exact resonance than the final outcome is the migration of the pair of planets with the rate similar to that of the gas giant at least for time of our simulations. Otherwise we observe a scattering of the Super-Earth from the disc. The evolution of planets immersed in the gaseous disc has been compared with their behaviour in the case of the classical three-body problem when the disc is absent.

  14. Surface density profiles of collisionless disc merger remnants

    E-Print Network [OSTI]

    Thorsten Naab; Ignacio Trujillo

    2006-03-01T23:59:59.000Z

    We present a detailed surface density analysis of a large sample of simulated collisionless mergers of disc galaxies with bulges (mass ratios 1:1, 2:1, 3:1, 4:1, and 6:1) and without bulges (mass ratios 1:1 and 3:1). They were classified, according to their bulge--to--total ($B/T$) ratio, either as a one-component system or as a two-component systems. In general projection effects change the classification of a remnant. Only merger remnants of discs with bulges show properties similar to observed early--type galaxies. Their B/T ratios are in the range $0.2discs for 6:1 remnants. We found distinct correlations between the fitting parameters which are very similar to observed relations (e.g. larger bulges have lower effective surface densities). No indications for a correlation between the surface density profiles and other global parameters are found. The remnants have properties similar to giant elliptical galaxies in the intermediate mass regime. A binary disc merger origin for all early-type galaxies, especially the most massive ones, is unlikely. Observed nearby merger remnants have properties similar to the simulated remnants. They can have formed from binary disc mergers and might evolve into early--type galaxies within a few Gyrs (abbreviated).

  15. Call Pre-Announcement for the first ERA-CAPS joint research call

    E-Print Network [OSTI]

    Greifswald, Ernst-Moritz-Arndt-Universität

    Call Pre-Announcement for the first ERA-CAPS joint research call: "Expanding the European Research Area in Molecular Plant Sciences" The new ERA-NET in molecular plant sciences, ERA-CAPS (Coordinating

  16. Migration of massive black hole binaries in self--gravitating accretion discs: Retrograde versus prograde

    E-Print Network [OSTI]

    Constanze Roedig; Alberto Sesana

    2013-07-24T23:59:59.000Z

    We study the interplay between mass transfer, accretion and gravitational torques onto a black hole binary migrating in a self-gravitating, retrograde circumbinary disc. A direct comparison with an identical prograde disc shows that: (i) because of the absence of resonances, the cavity size is a factor a(1+e) smaller for retrograde discs; (ii) nonetheless the shrinkage of a circular binary semi--major axis, a, is identical in both cases; (iii) a circular binary in a retrograde disc remains circular while eccentric binaries grow more eccentric. For non-circular binaries, we measure the orbital decay rates and the eccentricity growth rates to be exponential as long as the binary orbits in the plane of its disc. Additionally, for these co-planar systems, we find that interaction (~ non--zero torque) stems only from the cavity edge plus a(1+e) in the disc, i.e. for dynamical purposes, the disc can be treated as a annulus of small radial extent. We find that simple 'dust' models in which the binary- disc interaction is purely gravitational can account for all main numerical results, both for prograde and retrograde discs. Furthermore, we discuss the possibility of an instability occurring for highly eccentric binaries causing it to leave the disc plane, secularly tilt and converge to a prograde system. Our results suggest that there are two stable configurations for binaries in self-gravitating discs: the special circular retrograde case and an eccentric (e~ 0.6) prograde configuration as a stable attractor.

  17. Time-dependent models of two-phase accretion discs around black holes

    E-Print Network [OSTI]

    M. Mayer; J. E. Pringle

    2006-12-28T23:59:59.000Z

    We present time-dependent simulations of a two-phase accretion flow around a black hole. The accretion flow initially is composed of an optically thick and cool disc close to the midplane, while on top and below the disc there is a hot and optically thin corona. We consider several interaction mechanisms as heating of the disc by the corona and Compton cooling of the corona by the soft photons of the disc. Mass and energy can be exchanged between the disc and the corona due to thermal conduction. For the course of this more exploratory work, we limit ourselves to one particular model for a stellar mass black hole accreting at a low accretion rate. We confirm earlier both theoretical and observational results which show that at low accretion rates the disc close to the black hole cannot survive and is evaporated. Given the framework of this model, we now can follow through this phase of disc evaporation time dependently.

  18. 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.

  19. Call title: "The ocean of tomorrow" Call identifier: FP7-OCEAN-2010

    E-Print Network [OSTI]

    Milano-Bicocca, Università

    challenges in ocean management Theme 5 ­ Energy Area ENERGY.10.1 Call "The ocean of tomorrow" ­ Joining1 Call title: "The ocean of tomorrow" · Call identifier: FP7-OCEAN-2010 · Date of publication: 30, and Biotechnology (KBBE) - EUR 6 million from Theme 5 ­ Energy - EUR 10.5 million from Theme 6 ­ Environment

  20. SASIG Conference Call Minutes- August 9, 2012

    Broader source: Energy.gov [DOE]

    Kent Oelrich, Steering Committee Chair, welcomed everyone to the call. He also said “Thank You” to everyone who responded to his request for ideas about how the laboratory can prevent unintentional disclosure of classified information in unclassified e-mails.

  1. Better Buildings Working with Utilities Peer Exchange Call: Kick...

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

    April 21, 2011 Call Slides and Discussion Summary More Documents & Publications Finance Peer Exchange Kickoff Call Better Buildings Workforce Peer Exchange Call: Kick-off...

  2. Better Buildings Residential Network Peer Exchange Call Series...

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

    Energy Efficiency Call Slides and Discussion Summary January 22, 2015 Agenda Call Logistics and Introductions Opening Poll Residential Network and Peer Exchange Call...

  3. Lessons Learned: Peer Exchange Calls Fall 2014 | Department of...

    Energy Savers [EERE]

    Calls Fall 2014 Lessons Learned: Peer Exchange Calls Fall 2014 Better Buildings Residential Network, Lessons Learned: Peer Exchange Calls Fall 2014. Lessons Learned: Peer...

  4. On the black hole limit of rotating discs and rings

    E-Print Network [OSTI]

    Andreas Kleinwächter; Hendrick Labranche; Reinhard Meinel

    2010-07-20T23:59:59.000Z

    Solutions to Einstein's field equations describing rotating fluid bodies in equilibrium permit parametric (i.e. quasi-stationary) transitions to the extreme Kerr solution (outside the horizon). This has been shown analytically for discs of dust and numerically for ring solutions with various equations of state. From the exterior point of view, this transition can be interpreted as a (quasi) black hole limit. All gravitational multipole moments assume precisely the values of an extremal Kerr black hole in the limit. In the present paper, the way in which the black hole limit is approached is investigated in more detail by means of a parametric Taylor series expansion of the exact solution describing a rigidly rotating disc of dust. Combined with numerical calculations for ring solutions our results indicate an interesting universal behaviour of the multipole moments near the black hole limit.

  5. Disc amplitudes, picture changing and space-time actions

    E-Print Network [OSTI]

    Katrin Becker; Guangyu Guo; Daniel Robbins

    2011-06-16T23:59:59.000Z

    We study in detail the procedure for obtaining couplings of D-branes to closed string fields by evaluating string theory disc amplitudes. We perform a careful construction of the relevant vertex operators and discuss the effects of inserting the boundary state which encodes the presence of the D-brane. We confront the issue of non-decoupling of BRST-exact states and prove that the problem is evaded for the computations we need, thus demonstrating that our amplitudes are automatically gauge-invariant and independent of the distribution of picture charge. Finally, we compute explicitly the two-point amplitudes of two NS-NS fields or one NS-NS and one R-R field on the disc, and we carefully compare all the lowest order terms with predictions from supergravity.

  6. Characterising the Gravitational Instability in Cooling Accretion Discs

    E-Print Network [OSTI]

    Peter Cossins; Giuseppe Lodato; Cathie Clarke

    2008-11-21T23:59:59.000Z

    We perform numerical analyses of the structure induced by gravitational instabilities in cooling gaseous accretion discs. For low enough cooling rates a quasi-steady configuration is reached, with the instability saturating at a finite amplitude in a marginally stable disc. We find that the saturation amplitude scales with the inverse square root of the cooling parameter beta = t_cool / t_dyn, which indicates that the heating rate induced by the instability is proportional to the energy density of the induced density waves. We find that at saturation the energy dissipated per dynamical time by weak shocks due is of the order of 20 per cent of the wave energy. From Fourier analysis of the disc structure we find that while the azimuthal wavenumber is roughly constant with radius, the mean radial wavenumber increases with radius, with the dominant mode corresponding to the locally most unstable wavelength. We demonstrate that the density waves excited in relatively low mass discs are always close to co-rotation, deviating from it by approximately 10 per cent. This can be understood in terms of the flow Doppler-shifted phase Mach number -- the pattern speed self-adjusts so that the flow into spiral arms is always sonic. This has profound effects on the degree to which transport through self-gravity can be modelled as a viscous process. Our results thus provide (a) a detailed description of how the self-regulation mechanism is established for low cooling rates, (b) a clarification of the conditions required for describing the transport induced by self-gravity through an effective viscosity, (c) an estimate of the maximum amplitude of the density perturbation before fragmentation occurs, and (d) a simple recipe to estimate the density perturbation in different thermal regimes.

  7. Mirror Symmetry, D-Branes and Counting Holomorphic Discs

    E-Print Network [OSTI]

    Mina Aganagic; Cumrun Vafa

    2000-12-05T23:59:59.000Z

    We consider a class of special Lagrangian subspaces of Calabi-Yau manifolds and identify their mirrors, using the recent derivation of mirror symmetry, as certain holomorphic varieties of the mirror geometry. This transforms the counting of holomorphic disc instantons ending on the Lagrangian submanifold to the classical Abel-Jacobi map on the mirror. We recover some results already anticipated as well as obtain some highly non-trivial new predictions.

  8. Radial mixing and the transition between the thick and thin Galactic discs

    E-Print Network [OSTI]

    Misha Haywood

    2008-05-13T23:59:59.000Z

    The analysis of the kinematics of solar neighbourhood stars shows that the low and high metallicity tails of the thin disc are populated by objects which orbital properties suggest an origin in the outer and inner galactic disc, respectively. Signatures of radial migration are identified in various recent samples, and are shown to be responsible for the high metallicity dispersion in the age-metallicity distribution. Most importantly, it is shown that the population of low metallicity wanderers of the thin disc (-0.7disc (which terminal metallicity is about -0.2 dex). It implies that the thin disc at the solar circle has started to form stars at about this same metallicity. This is also consistent with the fact that 'transition' objects, which have alpha-element abundance intermediate between that of the thick and thin discs, are found in the range [-0.4,-0.2] dex. Once the metal-poor thin disc stars are recognised for what they are - wanderers from the outer thin disc - the parenthood between the two discs can be identified on stars genuinely formed at the solar circle through an evolutionary sequence in [alpha/Fe] and [Fe/H] . Another consequence is that stars that can be considered as truly resulting of the chemical evolution at the solar circle have a metallicity restricted to about [-0.2,+0.2] dex, confirming an old idea that most chemical evolution in the Milky Way have preceded the thin disc formation.

  9. Warped discs and the directional stability of jets in Active Galactic Nuclei

    E-Print Network [OSTI]

    Priyamvada Natarajan; Philip J. Armitage

    1999-06-27T23:59:59.000Z

    Warped accretion discs in Active Galactic Nuclei (AGN) exert a torque on the black hole that tends to align the rotation axis with the angular momentum of the outer disc. We compute the magnitude of this torque by solving numerically for the steady state shape of the warped disc, and verify that the analytic solution of Scheuer and Feiler (1996) provides an excellent approximation. We generalise these results for discs with strong warps and arbitrary surface density profiles, and calculate the timescale on which the black hole becomes aligned with the angular momentum in the outer disc. For massive holes and accretion rates of the order of the Eddington limit the alignment timescale is always short (less than a Myr), so that jets accelerated from the inner disc region provide a prompt tracer of the angular momentum of gas at large radii in the disc. Longer timescales are predicted for low luminosity systems, depending on the degree of anisotropy in the disc's hydrodynamic response to shear and warp, and for the final decay of modest warps at large radii in the disc that are potentially observable via VLBI. We discuss the implications of this for the inferred accretion history of those Active Galactic Nuclei whose jet directions appear to be stable over long timescales. The large energy deposition rate at modest disc radii during rapid realignment episodes should make such objects transiently bright at optical and infrared wavelengths.

  10. Three dimensional SPH simulations of radiation-driven warped accretion discs

    E-Print Network [OSTI]

    Stephen B. Foulkes; Carole A. Haswell; James R. Murray

    2006-01-06T23:59:59.000Z

    We present three dimensional smoothed particle hydrodynamics (SPH) calculations of warped accretion discs in X-ray binary systems. Geometrically thin, optically thick accretion discs are illuminated by a central radiation source. This illumination exerts a non-axisymmetric radiation pressure on the surface of the disc resulting in a torque that acts on the disc to induce a twist or warp. Initially planar discs are unstable to warping driven by the radiation torque and in general the warps also precess in a retrograde direction relative to the orbital flow. We simulate a number of X-ray binary systems which have different mass ratios using a number of different luminosities for each. Radiation-driven warping occurs for all systems simulated. For mass ratios q ~ 0.1 a moderate warp occurs in the inner disc while the outer disc remains in the orbital plane (c.f. X 1916-053). For less extreme mass ratios the entire disc tilts out of the orbital plane (c.f. Her X-1). For discs that are tilted out of the orbital plane in which the outer edge material of the disc is precessing in a prograde direction we obtain both positive and negative superhumps simultaneously in the dissipation light curve (c.f. V603 Aql).

  11. Methanol Along the Path from Envelope to Protoplanetary Disc

    E-Print Network [OSTI]

    Drozdovskaya, Maria N; Visser, Ruud; Harsono, Daniel; van Dishoeck, Ewine F

    2014-01-01T23:59:59.000Z

    Interstellar methanol is considered to be a parent species of larger, more complex organic molecules. A physicochemical simulation of infalling parcels of matter is performed for a low-mass star-forming system to trace the chemical evolution from cloud to disc. An axisymmetric 2D semi-analytic model generates the time-dependent density and velocity distributions, and full continuum radiative transfer is performed to calculate the dust temperature and the UV radiation field at each position as a function of time. A comprehensive gas-grain chemical network is employed to compute the chemical abundances along infall trajectories. Two physical scenarios are studied, one in which the dominant disc growth mechanism is viscous spreading, and another in which continuous infall of matter prevails. The results show that the infall path influences the abundance of methanol entering each type of disc, ranging from complete loss of methanol to an enhancement by a factor of > 1 relative to the prestellar phase. Critical ch...

  12. Global m=1 modes and migration of protoplanetary cores in eccentric protoplanetary discs

    E-Print Network [OSTI]

    J. C. B. Papaloizou

    2002-04-11T23:59:59.000Z

    We calculate global $m=1$ modes with low pattern speed corresponding to introducing a finite eccentricity into a protoplanetary disc. We consider disc models which are either isolated or contain one or two protoplanets orbiting in an inner cavity. Global modes that are strongly coupled to inner protoplanets are found to have disc orbits which tend to have apsidal lines antialigned with respect to those of the inner protoplanets. Other modes corresponding to free disc modes may be global over a large range of length scales and accordingly be long lived. We consider the motion of a protoplanet in the earth mass range embedded in an eccentric disc and determine the equilibrium orbits which maintain fixed apsidal alignment with respect to the disc gas orbits. Equilibrium eccentricities are found to be comparable or possibly exceed the disc eccentricity. We then approximately calculate the tidal interaction with the disc in order to estimate the orbital migration rate. Results are found to deviate from the case of axisymmetric disc with near circular protoplanet orbit once eccentricities of protoplanet and disc orbits become comparable to the disc aspect ratio in magnitude. Aligned protoplanet orbits with very similar eccentricity to that of the gas disc are found to undergo litle eccentricity change while undergoing inward migration in general. However, for significantly larger orbital eccentricities, migration may be significantly reduced or even reverse from inwards to outwards. Thus the existence of global non circular motions in discs with radial excursions comparable to the semi-thickness may have important consequences for the migration and survival of protoplanetary cores in the earth mass range.

  13. Networking Call for Residential Network Members Peer Exchange...

    Energy Savers [EERE]

    Networking Call for Residential Network Members Peer Exchange Call Networking Call for Residential Network Members Peer Exchange Call March 12, 2015 12:30PM to 2:0...

  14. Chirac calls ITER essential for planet's future

    E-Print Network [OSTI]

    fusion reactor. "Today, our energy consumption has put us in danger. It's mainly based on oil, gasChirac calls ITER essential for planet's future CADARACHE, France, June 30 (AFP) - French President in southern France as vital to the planet's future, praising European solidarity in sealing the deal. "This

  15. Tesla TechFair Call for Proposals

    E-Print Network [OSTI]

    are celebrating Nikola Tesla, in conjunction with Tesla in New York, an opera by filmmaker Jim Jarmusch & composer | 4:00-6:00 PM | Spanos Auditorium/Great Hall, Thayer | Free Discover how Nikola Tesla's inventionsTesla TechFair Call for Proposals Thayer School of Engineering and the Hopkins Center

  16. CALL FOR PAPERS Annals of Operations Research

    E-Print Network [OSTI]

    environmental management, (vi) novel modelling techniques for environmental cooperation, and policy initiativesCALL FOR PAPERS Annals of Operations Research Special Volume on Collaborative Environmental and environmental degradation are rising all over the world. Due to the global effect of environmental deterioration

  17. CALL FOR PAPERS International Conference on

    E-Print Network [OSTI]

    Grout, Vic

    CALL FOR PAPERS 6th International Conference on Bioinformatics and Computational Biology March 24 challenges. The 6th International Conference on Bioinformatics and Computational Biology (BICoB) will provide of bioinformatics, computational biology, systems biology, medical informatics and the related areas. We also

  18. Global MHD simulations of stratified and turbulent protoplanetary discs. I. Model properties

    E-Print Network [OSTI]

    Sebastien Fromang; Richard P. Nelson

    2006-06-29T23:59:59.000Z

    We present the results of global 3-D MHD simulations of stratified and turbulent protoplanetary disc models. The aim of this work is to develop thin disc models capable of sustaining turbulence for long run times, which can be used for on-going studies of planet formation in turbulent discs. The results are obtained using two codes written in spherical coordinates: GLOBAL and NIRVANA. Both are time--explicit and use finite differences along with the Constrained Transport algorithm to evolve the equations of MHD. In the presence of a weak toroidal magnetic field, a thin protoplanetary disc in hydrostatic equilibrium is destabilised by the magnetorotational instability (MRI). When the resolution is large enough (25 vertical grid cells per scale height), the entire disc settles into a turbulent quasi steady-state after about 300 orbits. Angular momentum is transported outward such that the standard alpha parameter is roughly 4-6*10^{-3}. We find that the initial toroidal flux is expelled from the disc midplane and that the disc behaves essentially as a quasi-zero net flux disc for the remainder of the simulation. As in previous studies, the disc develops a dual structure composed of an MRI--driven turbulent core around its midplane, and a magnetised corona stable to the MRI near its surface. By varying disc parameters and boundary conditions, we show that these basic properties of the models are robust. The high resolution disc models we present in this paper achieve a quasi--steady state and sustain turbulence for hundreds of orbits. As such, they are ideally suited to the study of outstanding problems in planet formation such as disc--planet interactions and dust dynamics.

  19. Webinar: Testing Oxygen Reduction Reaction Activity with the Rotating Disc Electrode Technique

    Broader source: Energy.gov [DOE]

    Video recording of the Fuel Cell Technologies Office webinar, Testing Oxygen Reduction Reaction Activity with the Rotating Disc Electrode Technique, originally presented on March 12, 2013.

  20. Dust filtration at gap edges: Implications for the spectral energy distributions of discs with embedded planets

    E-Print Network [OSTI]

    W. K. M. Rice; Philip J. Armitage; Kenneth Wood; Giuseppe Lodato

    2006-09-29T23:59:59.000Z

    The spectral energy distributions (SEDs) of some T Tauri stars display a deficit of near-IR flux that could be a consequence of an embedded Jupiter-mass planet partially clearing an inner hole in the circumstellar disc. Here, we use two-dimensional numerical simulations of the planet-disc interaction, in concert with simple models for the dust dynamics, to quantify how a planet influences the dust at different radii within the disc. We show that pressure gradients at the outer edge of the gap cleared by the planet act as a filter - letting particles smaller than a critical size through to the inner disc while holding back larger particles in the outer disc. The critical particle size depends upon the disc properties, but is typically of the order of 10 microns. This filtration process will lead to discontinuous grain populations across the planet's orbital radius, with small grains in the inner disc and an outer population of larger grains. We show that this type of dust population is qualitatively consistent with SED modelling of systems that have optically thin inner holes in their circumstellar discs. This process can also produce a very large gas-to-dust ratio in the inner disc, potentially explaining those systems with optically thin inner cavities that still have relatively high accretion rates.

  1. The spectra of accretion discs in low-mass X-ray binaries

    E-Print Network [OSTI]

    R. R. Ross; A. C. Fabian

    1995-11-14T23:59:59.000Z

    We present self-consistent models for the radiative transfer in Shakura-Sunyaev accretion discs in bright low-mass X-ray binaries (LMXB). Our calculations include the full effects of incoherent Compton scattering and the vertical temperature structure within the disc, as well as the effects of Doppler blurring and gravitational redshift. We find that the observed X-ray spectra are well fit by exponentially cutoff power-law models. The difference between the observed total spectrum and our calculated disc spectrum should reveal the spectrum of the disc/neutron star boundary layer and other emitting regions considered to be present in LMXB.

  2. Neutron scattering residual stress measurements on gray cast iron brake discs

    SciTech Connect (OSTI)

    Spooner, S.; Payzant, E.A.; Hubbard, C.R. [and others

    1996-11-01T23:59:59.000Z

    Neutron diffraction was used to investigate the effects of a heat treatment designed to remove internal residual stresses in brake discs. It is believed that residual stresses may change the rate of deformation of the discs during severe braking conditions when the disc temperature is increased significantly. Neutron diffraction was used to map out residual strain distributions in a production disc before and after a stress-relieving heat treatment. Results from these neutron diffraction experiments show that some residual strains were reduced by as much as 400 microstrain by stress relieving. 5 refs., 5 figs., 1 tab.

  3. Properties of vertically self-gravitating accretion discs with a dissipative corona

    E-Print Network [OSTI]

    Fazeleh Khajenabi; Peter Duffy

    2008-05-30T23:59:59.000Z

    The steady-state structure of a disc with a corona is analyzed when the vertical component of the gravitational force due to the self-gravity of the disc is considered. For the energy exchange between the disc and the corona, we assume a fraction f of the dissipated energy inside the accretion disc is transported to the corona via the magnetic tubes. Analytical solutions corresponding to a prescription for f (in which this parameter directly depends on the ratio of the gas pressure to the total pressure) or free f are presented and their physical properties are studied in detail. We show that the existence of the corona not only decreases the temperature of the disc, but also increases the surface density.The vertical component of the gravitational force due to the self-gravity of the disc decreases the self-gravitating radius and the mass of the fragments at this radius. However, as more energy is transported from the disc to the corona, the effect of the vertical component of the gravitational force due to the self-gravity of the disc on the self-gravitating radius becomes weaker, though the mass of the fragments is reduced irrespective of the amount of the energy exchange from the disc to the corona.

  4. Hydrodynamic Simulations of Propagating Warps and Bending Waves In Accretion Discs

    E-Print Network [OSTI]

    Richard P. Nelson; John C. B. Papaloizou

    1999-07-06T23:59:59.000Z

    We present the results of a study of propagating warp or bending waves in accretion discs. Three dimensional hydrodynamic simulations were performed using SPH, and the results of these are compared with calculations based on the linear theory of warped discs. We consider primarily the physical regime in which the dimensionless viscosity parameter `alpha' disc aspect ratio, so that bending waves are expected to propagate. We also present calculations in which `alpha' > H/r, where the warps are expected to behave diffusively. Small amplitude perturbations are studied in both Keplerian and slightly non Keplerian discs, and we find that the SPH results can be reasonably well fitted by those of the linear theory. The main results of these calculations are: (1) the warp in Keplerian discs when `alpha' H/r, (3) the non Keplerian discs exhibit a substantially more dispersive behaviour of the warps. Initially imposed higher amplitude nonlinear warping disturbances were studied in Keplerian discs. The results indicate that nonlinear warps can lead to the formation of shocks, and that the evolution of the warp becomes less wave-like and more diffusive in character. This work is relevant to the study of the warped accretion discs that may occur around Kerr black holes or in misaligned binary systems. The results indicate that SPH can accurately model the hydrodynamics of warped discs, even when using rather modest numbers of particles.

  5. Dependence of fragmentation in self-gravitating accretion discs on small scale structure

    E-Print Network [OSTI]

    Young, Matthew D

    2015-01-01T23:59:59.000Z

    We propose a framework for understanding the fragmentation criterion for self-gravitating discs which, in contrast to studies that emphasise the `gravoturbulent' nature of such discs, instead focuses on the properties of their quasi-regular spiral structures. Within this framework there are two evolutionary paths to fragmentation: i) collapse on the free-fall time, which requires that the ratio of cooling time to dynamical time ($\\beta$) $disc. We perform 2D grid simulations which demonstrate numerically converged fragmentation at $\\beta disc. Such simulations thus only allow fragmentation via route i) above...

  6. Eccentric discs in binaries with intermediate mass ratios: Superhumps in the VY Sculptoris stars

    E-Print Network [OSTI]

    J. R. Murray; B. Warner; D. T. Wickramasinghe

    2000-02-23T23:59:59.000Z

    We investigate the role of the eccentric disc resonance in systems with mass ratios q greater than 1/4, and demonstrate the effects that changes in the mass flux from the secondary star have upon the disc radius and structure. The addition of material with low specific angular momentum to its outer edge restricts a disc radially. Should the mass flux from the secondary be reduced, it is possible for the disc in a system with mass ratio as large as 1/3 to expand to the 3:1 eccentric inner Lindblad resonance and for superhumps to be excited.

  7. Strong effect of the cluster environment on the size of protoplanetary discs?

    E-Print Network [OSTI]

    Vincke, Kirsten; Pfalzer, Susanne

    2015-01-01T23:59:59.000Z

    Context. Most stars are born in clusters, thus the protoplanetary discs surrounding the newly formed stars might be influenced by this environment. Isolated star-disc encounters have previously been studied, and it was shown that very close encounters are necessary to completely destroy discs. However, relatively distant encounters are still able to change the disc size considerably. Aims. We quantify the importance of disc-size reduction that is due to stellar encounters in an entire stellar population. Methods. We modelled young, massive clusters of different densities using the code Nbody6 to determine the statistics of stellar encounter parameters. In a second step, we used these parameters to investigate the effect of the environments on the disc size. For this purpose, we performed a numerical experiment with an artificial initial disc size of 105 AU. Results. We quantify to which degree the disc size is more sensitive to the cluster environment than to the disc mass or frequency. We show that in all in...

  8. Call Numbers Explained 1 8/23/2012 Call Numbers Explained

    E-Print Network [OSTI]

    Su, Xiao

    . The second method is the Library of Congress Classification system, which is used to identify university. In the library, books are organized by call number. 3. A call number classifies a book by its subject and tells in the library. 6. The King Library is unusual because it is both a public library and a university library

  9. Call title : FP7-ENV-2010 Call identifier: FP7-ENV-2010

    E-Print Network [OSTI]

    Milano-Bicocca, Università

    .1.1.5-1 Impact of ocean acidification in the Mediterranean in a changing climate Collaborative Project (small called: ACTIVITY/ AREA TOPICS CALLED FUNDING SCHEMES ACTIVITY 6.1. CLIMATE CHANGE, POLLUTION AND RISKS.1.2. ENV.2010.1.1.2-1 Atmospheric chemistry and climate change interactions Collaborative Project (large

  10. Data and Evaluation Kickoff Call | Department of Energy

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

    Data and Evaluation Peer Exchange Kick-off Call to Discuss Key Topics for Peer- to -Peer Discussions, Call Slides and Discussion Summary, May 12, 2011. Call Slides and Discussion...

  11. Dark Matter Disc Enhanced Neutrino Fluxes from the Sun and Earth

    E-Print Network [OSTI]

    Tobias Bruch; Annika H. G. Peter; Justin Read; Laura Baudis; George Lake

    2009-04-21T23:59:59.000Z

    As disc galaxies form in a hierarchical cosmology, massive merging satellites are preferentially dragged towards the disc plane. The material accreted from these satellites forms a dark matter disc that contributes 0.25 - 1.5 times the non-rotating halo density at the solar position. Here, we show the importance of the dark disc for indirect dark matter detection in neutrino telescopes. Previous predictions of the neutrino flux from WIMP annihilation in the Earth and the Sun have assumed that Galactic dark matter is spherically distributed with a Gaussian velocity distribution, the standard halo model. Although the dark disc has a local density comparable to the dark halo, its higher phase space density at low velocities greatly enhances capture rates in the Sun and Earth. For typical dark disc properties, the resulting muon flux from the Earth is increased by three orders of magnitude over the SHM, while for the Sun the increase is an order of magnitude. This significantly increases the sensitivity of neutrino telescopes to fix or constrain parameters in WIMP models. The flux from the Earth is extremely sensitive to the detailed properties of the dark disc, while the flux from the Sun is more robust. The enhancement of the muon flux from the dark disc puts the search for WIMP annihilation in the Earth on the same level as the Sun for WIMP masses < 100 GeV.

  12. Magnetized accretion-ejection structures IV. Magnetically-driven jets from resistive, viscous, Keplerian discs

    E-Print Network [OSTI]

    Fabien Casse; Jonathan Ferreira

    1999-11-25T23:59:59.000Z

    We present steady-state calculations of self-similar magnetized accretion discs driving cold, adiabatic, non-relativistic jets. For the first time, both the magnetic torque due to the jets and a turbulent "viscous" torque are taken into account. This latter torque allows a dissipation of the accretion power as radiation at the disc surfaces, while the former predominantly provides jets with power. The parameter space of these structures has been explored. It is characterized by four free parameters, namely the disc aspect ratio and three MHD turbulence parameters, related to the anomalous magnetic diffusivities and viscosity. It turns out that launching cold jets from thin, dissipative discs implies anisotropic turbulent dissipation. Jets that asymptotically reach a high Alfvenic Mach number are only produced by weakly dissipative discs. We obtained general analytical relations between disc and jet quantities that must be fulfilled by any steady-state model of cold jets, launched from a large radial extension of thin discs. We also show that such discs cannot have a dominant viscous torque. This is because of the chosen geometry, imposing the locus of the Alfven surface. Some observational consequences of these cold magnetized accretion-ejection structures are also briefly discussed.

  13. A SCUBA-2 850 micron Survey of Protoplanetary Discs in the IC 348 Cluster

    E-Print Network [OSTI]

    Cieza, L; Kourkchi, E; Andrews, S; Casassus, S; Graves, S; Schreiber, M

    2015-01-01T23:59:59.000Z

    We present 850 micron observations of the 2-3 Myr cluster IC 348 in the Perseus molecular cloud using the SCUBA-2 camera on the James Clerk Maxwell Telescope. Our SCUBA-2 map has a diameter of 30 arcmin and contains ~370 cluster members, including ~200 objects with IR excesses. We detect a total of 13 discs. Assuming standard dust properties and a gas to dust mass ratio of 100, we derive disc masses ranging from 1.5 to 16 M_JUP . We also detect 8 Class 0/I protostars. We find that the most massive discs (M_Disc > 3 MJUP ; 850 micron fux > 10 mJy) in IC 348 tend to be transition objects according to the characteristic "dip" in their infrared Spectral Energy Distributions (SEDs). This trend is also seen in other regions. We speculate that this could be an initial conditions effect (e.g., more massive discs tend to form giant planets that result in transition disc SEDs) and/or a disc evolution effect (the formation of one or more massive planets results in both a transition disc SED and a reduction of the accret...

  14. Quantum McKay correspondence for disc invariants of orbifold vertex

    E-Print Network [OSTI]

    Hua-Zhong Ke; Jian Zhou

    2014-10-16T23:59:59.000Z

    In this note, we describe a a systematic procedure to find toric crepant resolutions of orbifold vertex, and show that the generating series of certain disc invariants of the orbifold vertex can be suitably identified with the generating series of certain disc invariants of its toric crepant resolutions.

  15. Gene Calling Standards (GSC8 Meeting)

    ScienceCinema (OSTI)

    Kyrpides, Nikos [Genome Biology Program, DOE JGI

    2011-04-28T23:59:59.000Z

    The Genomic Standards Consortium was formed in September 2005. It is an international, open-membership working body which promotes standardization in the description of genomes and the exchange and integration of genomic data. The 2009 meeting was an activity of a five-year funding "Research Coordination Network" from the National Science Foundation and was organized held at the DOE Joint Genome Institute with organizational support provided by the JGI and by the University of California - San Diego. Nikos Kyrpides of the DOE Joint Genome Institute discusses gene calling standards at the Genomic Standards Consortium's 8th meeting at the DOE JGI in Walnut Creek, Calif. on Sept. 10, 2009.

  16. Call issued for Proton Radiography Facility proposals

    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 3,625govInstrumentstdmadapInactiveVisiting the TWPSuccess StoriesFebruary 26,Computers »Cafeterias link toCall

  17. High accretion rates in magnetised Keplerian discs mediated by a Parker instability driven dynamo

    E-Print Network [OSTI]

    Johansen, Anders

    2008-01-01T23:59:59.000Z

    Hydromagnetic stresses in accretion discs have been the subject of intense theoretical research over the past one and a half decades. Most of the disc simulations have assumed a small initial magnetic field and studied the turbulence that arises from the magnetorotational instability. However, gaseous discs in galactic nuclei and in some binary systems are likely to have significant initial magnetisation. Motivated by this, we performed ideal magnetohydrodynamic simulations of strongly magnetised, vertically stratified discs in a Keplerian potential. Our initial equilibrium configuration, which has an azimuthal magnetic field in equipartion with thermal pressure, is unstable to the Parker instability. This leads to the expelling of magnetic field arcs, anchored in the midplane of the disc, to around five scale heights from the midplane. Transition to turbulence happens primarily through magnetorotational instability in the resulting vertical fields, although magnetorotational shear instability in the unpertur...

  18. Better Buildings Workforce Peer Exchange Call: Kick-off | Department...

    Energy Savers [EERE]

    Documents & Publications Better Buildings Working with Utilities Peer Exchange Call: Kick-off Administering Nonprofit Energy Efficiency Programs Finance Peer Exchange Kickoff Call...

  19. Secretary of Energy Advisory Board Hosts Conference Call on Shale...

    Energy Savers [EERE]

    of Energy Advisory Board Hosts Conference Call on Shale Gas Draft Report Secretary of Energy Advisory Board Hosts Conference Call on Shale Gas Draft Report November 10, 2011 -...

  20. PNNL: VOLTTRON Commercialization (CBI/ET Open Call) - 2015 Peer...

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

    VOLTTRON Commercialization (CBIET Open Call) - 2015 Peer Review PNNL: VOLTTRON Commercialization (CBIET Open Call) - 2015 Peer Review Presenter: Srinivas Katipamula, PNNL View...

  1. Secretary Chu to Host Conference Call Announcing the Winners...

    Energy Savers [EERE]

    to Host Conference Call Announcing the Winners of the America's Next Top Energy Innovator Challenge Secretary Chu to Host Conference Call Announcing the Winners of the America's...

  2. Research Call to DOE/Federal Laboratories: Technical Support...

    Office of Environmental Management (EM)

    Research Call to DOEFederal Laboratories: Technical Support for Interconnection-Level Electric Infrastructure Planning RC-BM-2010; Due May 3, 2010. Research Call to DOEFederal...

  3. Program Sustainability Peer Exchange Call: Transitioning to a...

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

    7, 2013 Program Sustainability Peer Exchange Call: Transitioning to a Utility Funded Program Environment: What Do I Need To Know? Call Slides and Discussion Summary Agenda *...

  4. Call center demand forecasting : improving sales calls prediction accuracy through the combination of statistical methods and judgmental forecast

    E-Print Network [OSTI]

    Boulin, Juan Manuel

    2010-01-01T23:59:59.000Z

    Call centers are important for developing and maintaining healthy relationships with customers. At Dell, call centers are also at the core of the company's renowned direct model. For sales call centers in particular, the ...

  5. On the fragility of nuclear stellar discs against galaxy mergers: surviving photometric and kinematic signatures of nuclear discs

    E-Print Network [OSTI]

    Sarzi, M; Dotti, M

    2015-01-01T23:59:59.000Z

    Nuclear stellar discs (NSDs) can help to constrain the assembly history of their host galaxies, as long as we can assume them to be fragile structures that are disrupted during merger events. In this work we investigate the fragility of NSDs by means of N-body simulations reproducing the last phases of a galaxy encounter, when the nuclear regions of the two galaxies merge. For this, we exposed a NSD set in the gravitational potential of the bulge and supermassive black hole of a primary galaxy to the impact of the supermassive black hole from a secondary galaxy. We explored merger events of different mass ratios, from major mergers with a 1:1 mass ratio to intermediate and minor interactions with 1:5 and 1:10 ratios, while considering various impact geometries. We analyse the end results of such mergers from different viewing angles and looked for possible photometric and kinematic signatures of the presence of a disc in the remnant surface density and velocity maps, while adopting detection limits from real ...

  6. Iron line profiles and self-shadowing from relativistic thick accretion discs

    E-Print Network [OSTI]

    Sheng-Miao Wu; Ting-Gui Wang

    2008-07-11T23:59:59.000Z

    We present Fe Kalpha line profiles from and images of relativistic discs with finite thickness around a rotating black hole using a novel code. The line is thought to be produced by iron fluorescence of a relatively cold X-ray illuminated material in the innermost parts of the accretion disc and provides an excellent diagnostic of accretion flows in the vicinity of black holes. Previous studies have concentrated on the case of a thin, Keplerian accretion disc. This disc must become thicker and sub-Keplerian with increasing accretion rates. These can affect the line profiles and in turn can influence the estimation of the accretion disc and black hole parameters from the observed line profiles. We here embark on, for the first time, a fully relativistic computation which offers key insights into the effects of geometrical thickness and the sub-Keplerian orbital velocity on the line profiles. We include all relativistic effects such as frame-dragging, Doppler boost, time dilation, gravitational redshift and light bending. We find that the separation and the relative height between the blue and red peaks of the line profile diminish as the thickness of the disc increases. This code is also well-suited to produce accretion disc images. We calculate the redshift and flux images of the accretion disc and find that the observed image of the disc strongly depends on the inclination angle. The self-shadowing effect appears remarkable for a high inclination angle, and leads to the black hole shadow being completely hidden by the disc itself.

  7. The Aurora Calling Tree Updated May 14, 2010

    E-Print Network [OSTI]

    Maxwell, Bruce D.

    The Aurora Calling Tree Updated May 14, 2010 1. If you see the Aurora first, call the next person Only circles. (However, if an early circle person happens to see the Aurora after 11:00, please CALL-529-7066 Norm Williams 406-579-1882 #12;The Aurora Calling Tree Updated May 14, 2010 1. If you see the Aurora

  8. Jamming Transition and Inherent Structures of Hard Spheres and Discs

    E-Print Network [OSTI]

    Misaki Ozawa; Takeshi Kuroiwa; Atsushi Ikeda; Kunimasa Miyazaki

    2012-11-17T23:59:59.000Z

    Recent studies show that volume fractions $\\phiJ$ at the jamming transition of frictionless hard spheres and discs are not uniquely determined but exist over a continuous range. Motivated by this observation, we numerically investigate dependence of $\\phiJ$ on the initial configurations of the parent fluids equilibrated at a fraction $\\phiini$, before compressing to generate a jammed packing. We find that $\\phiJ$ remains constant when $\\phiini$ is small but sharply increases when $\\phiini$ exceeds the dynamic transition point which the mode-coupling theory predicts. We carefully analyze configurational properties of both jammed packings and parent fluids and find that, while all jammed packings remain isostatic, the increase of $\\phiJ$ is accompanied with subtle but distinct changes of (i) local orders, (ii) a static length scale, and (iii) an exponent of the finite size scaling. These results quantitatively support the scenario of the random first order transition theoryof the glass transition.

  9. The Complete Jamming Landscape of Confined Hard Discs

    E-Print Network [OSTI]

    S. S. Ashwin; Richard k. Bowles

    2009-03-25T23:59:59.000Z

    An exact description of the complete jamming landscape is developed for a system of hard discs of diameter $\\sigma$, confined between two lines separated by a distance $1+\\sqrt{3/4} < H/\\sigma < 2$. By considering all possible local packing arrangements, the generalized ensemble partition function of jammed states is obtained using the transfer matrix method, which allows us to calculate the configurational entropy and the equation of state for the packings. Exploring the relationship between structural order and packing density, we find that the geometric frustration between local packing environments plays an important role in determining the density distribution of jammed states and that structural "randomness" is a non-monotonic function of packing density. Molecular dynamics simulations show that the properties of the equilibrium liquid are closely related to those of the landscape.

  10. Normal modes analysis of the microscopic dynamics in hard discs

    E-Print Network [OSTI]

    Carolina Brito; Matthieu Wyart

    2008-05-09T23:59:59.000Z

    We estimate numerically the normal modes of the free energy in a glass of hard discs. We observe that, near the glass transition or after a rapid quench deep in the glass phase, the density of states (i) is characteristic of a marginally stable structure, in particular it di splays a frequency scale $\\omega^*\\sim p^{1/2}$, where $p$ is the pressure and (ii) gives a faithful representation of the short-time dyn amics. This brings further evidences that the boson peak near the glass transition corresponds to the relaxation of marginal modes of a we akly-coordinated structure, and implies that the mean square displacement in the glass phase is anomalously large and goes as $ \\sim p^{-3/2}$, a prediction that we check numerically.

  11. Massive planets in FU Orionis discs: implications for thermal instability models

    E-Print Network [OSTI]

    G. Lodato; C. J. Clarke

    2004-06-10T23:59:59.000Z

    FU Orionis are young stellar objects undergoing episodes of enhanced luminosity, which are generally ascribed to a sudden increase of mass accretion rate in the surrounding protostellar disc. Models invoking a thermal instability in the disc are able to reproduce many features of the outburst, but cannot explain the rapid rise time-scale observed in many cases. Here we explore the possibility (originally suggested by Clarke & Syer 1996) that the thermal instability is triggered away from the disc inner edge (at a distance of $\\approx 10R_{\\odot}$ from the central protostar) due to the presence of a massive planet embedded in the disc. We have constructed simple, one-dimensional, time-dependent models of the disc evolution, taking into account both the interaction between the disc and the planet, and the thermal evolution of the disc. We are indeed able to reproduce rapid rise outbursts (with rise time-scale $\\approx 1$ yr), with a planet mass $M_{\\mathrm{s}}=10-15M_{\\mathrm{Jupiter}}$. We show that the luminosity and the duration of the outbursts are increasing functions of planet mass. We also show that the inward migration of the planet is significantly slowed once it reaches the radius where it is able to trigger FU Orionis outbursts, thus suggesting that a single planet may be involved in triggering several outbursts.

  12. On fan-shaped cold MHD winds from Keplerian accretion discs

    E-Print Network [OSTI]

    Ferreira, Jonathan

    2012-01-01T23:59:59.000Z

    We investigate under which conditions cold, fan-shaped winds can be steadily launched from thin (Keplerian) accretion discs. Such winds are magneto-centrifugal winds launched from a thin annulus in the disc, along open magnetic field lines that fan out above the disc. In principle, such winds could be found in two situations: (1) at the interface between an inner Jet Emitting Disc, which is itself powering magneto-centrifugally driven winds, and an outer standard accretion disc; (2) at the interface between an inner closed stellar magnetosphere and the outer standard accretion disc. We refer to Terminal or T-winds to the former kind and to Magnetospheric or M-winds to the latter. The full set of resistive and viscous steady state MHD equations are analyzed for the disc (the annulus), which allow us to derive general expressions valid for both configurations. We find that, under the framework of our analysis, the only source of energy able to power any kind of fan-shaped winds is the viscous transport of rotat...

  13. High accretion rates in magnetised Keplerian discs mediated by a Parker instability driven dynamo

    E-Print Network [OSTI]

    Anders Johansen; Yuri Levin

    2008-08-26T23:59:59.000Z

    Hydromagnetic stresses in accretion discs have been the subject of intense theoretical research over the past one and a half decades. Most of the disc simulations have assumed a small initial magnetic field and studied the turbulence that arises from the magnetorotational instability. However, gaseous discs in galactic nuclei and in some binary systems are likely to have significant initial magnetisation. Motivated by this, we performed ideal magnetohydrodynamic simulations of strongly magnetised, vertically stratified discs in a Keplerian potential. Our initial equilibrium configuration, which has an azimuthal magnetic field in equipartion with thermal pressure, is unstable to the Parker instability. This leads to the expelling of magnetic field arcs, anchored in the midplane of the disc, to around five scale heights from the midplane. Transition to turbulence happens primarily through magnetorotational instability in the resulting vertical fields, although magnetorotational shear instability in the unperturbed azimuthal field plays a significant role as well, especially in the midplane where buoyancy is weak. High magnetic and hydrodynamical stresses arise, yielding an effective $\\alpha$-value of around 0.1 in our highest resolution run. Azimuthal magnetic field expelled by magnetic buoyancy from the disc is continuously replenished by the stretching of a radial field created as gas parcels slide in the linear gravity field along inclined magnetic field lines. This dynamo process, where the bending of field lines by the Parker instability leads to re-creation of the azimuthal field, implies that highly magnetised discs are astrophysically viable and that they have high accretion rates.

  14. Eccentricity growth of planetesimals in a self-gravitating protoplanetary disc

    E-Print Network [OSTI]

    M. Britsch; C. J. Clarke; G. Lodato

    2008-01-14T23:59:59.000Z

    We investigate the orbital evolution of planetesimals in a self-gravitating circumstellar disc in the size regime ($\\sim 1-5000$ km) where the planetesimals behave approximately as test particles in the disc's non-axisymmetric potential. We find that the particles respond to the stochastic, regenerative spiral features in the disc by executing large random excursions (up to a factor of two in radius in $\\sim 1000$ years), although typical random orbital velocities are of order one tenth of the Keplerian speed. The limited time frame and small number of planetesimals modeled does not permit us to discern any {\\it net} direction of planetesimal migration. Our chief conclusion is that the high eccentricities ($\\sim 0.1$) induced by interaction with spiral features in the disc is likely to be highly unfavourable to the collisional growth of planetesimals in this size range while the disc is in the self-gravitating regi me. Thus {\\it if}, as recently argued by Rice et al 2004, 2006, the production of planetesimals gets under way when the disc is in the self-gravitating regime (either at smaller planetesimal size scales, where gas drag is important, or via gravitational fragmentation of the solid component), then the planetesimals thus produced would not be able to grow collisionally until the disc ceased to be self-gravitating. It is unclear, however,given the large amplitude excursions undergone by planetesimals in the self-gravitating disc, whether they would be retained in the disc throughout this period, or whether they would instead be lost to the central star.

  15. Storm fronts over galaxy discs: Models of how waves generate extraplanar gas and its anomalous kinematics

    E-Print Network [OSTI]

    Curtis Struck; Daniel C. Smith

    2009-05-15T23:59:59.000Z

    The existence of partially ionized, diffuse gas and dust clouds at kiloparsec scale distances above the central planes of edge-on, galaxy discs was an unexpected discovery about 20 yrs ago. Subsequent observations showed that this EDIG (extended or extraplanar diffuse interstellar gas) has rotation velocities approximately 10-20% lower than those in the central plane, and have been hard to account for. Here we present results of hydrodynamic models, with radiative cooling and heating from star formation. We find that in models with star formation generated stochastically across the disc an extraplanar gas layer is generated as long as the star formation is sufficiently strong. However, this gas rotates at nearly the same speed as the mid-plane gas. We then studied a range of models with imposed spiral or bar waves in the disc. EDIG layers were also generated in these models, but primarily over the wave regions, not over the entire disc. Because of this partial coverage, the EDIG clouds move radially, as well as vertically, with the result that observed kinematic anomalies are reproduced. The implication is that the kinematic anomalies are the result of three-dimensional motions when the cylindrical symmetry of the disc is broken. Thus, the kinematic anomalies are the result of bars or strong waves, and more face-on galaxies with such waves should have an asymmetric EDIG component. The models also indicate that the EDIG can contain a significant fraction of cool gas, and that some star formation can be triggered at considerable heights above the disc midplane. We expect all of these effects to be more prominent in young, forming discs, to play a role in rapidly smoothing disc asymmetries, and in working to self-regulate disc structure.

  16. Maximally Random Jamming of Two-Dimensional One-Component and Binary Hard Disc Fluids

    E-Print Network [OSTI]

    Xinliang Xu; Stuart A. Rice

    2010-10-05T23:59:59.000Z

    We report calculations of the density of maximally random jamming (aka random close packing) of one-component and binary hard disc fluids. The theoretical structure used provides a common framework for description of the hard disc liquid to hexatic, the liquid to hexagonal crystal and the liquid-to-maximally random jammed state transitions. Our analysis is based on locating a particular bifurcation of the solutions of the integral equation for the inhomogeneous single particle density at the transition between different spatial structures. The bifurcation of solutions we study is initiated from the dense metastable fluid, and we associate it with the limit of stability of the fluid, which we identify with the transition from the metastable fluid to a maximally random jammed state. For the one-component hard disc fluid the predicted packing fraction at which the metastable fluid to maximally random jammed state transition occurs is 0.84, in excellent agreement with the experimental value 0.84 \\pm 0.02. The corresponding analysis of the limit of stability of a binary hard disc fluid with specified disc diameter ratio and disc composition requires extra approximations in the representations of the direct correlation function, the equation of state, and the number of order parameters accounted for. Keeping only the order parameter identified with the largest peak in the structure factor of the highest density regular lattice with the same disc diameter ratio and disc composition as the binary fluid, the predicted density of maximally random jamming is found to be 0.84 to 0.87, depending on the equation of state used, and very weakly dependent on the ratio of disc diameters and the fluid composition, in agreement with both experimental data and computer simulation data.

  17. On the accumulation of solid bodies in global turbulent protoplanetary disc models

    E-Print Network [OSTI]

    Sebastien Fromang; Richard P. Nelson

    2005-09-23T23:59:59.000Z

    We study the migration of solid bodies in turbulent protoplanetary accretion discs by means of global MHD simulations. The bodies range in size from 5 centimetres up to 1 metre, and so include objects whose migration is expected to be the most rapid due to gas drag interaction with the disc. As they drift inward through the disc, some of them are trapped in regions where gas pressure maxima are created by long lived anticyclonic vortices. This accumulation is very efficient, locally increasing the dust--to--gas ratio by a factor > 100 in some cases. We discuss the possible implications of this result for theories of planet formation.

  18. A viscous-convective instability in laminar Keplerian thin discs. II. Anelastic approximation

    E-Print Network [OSTI]

    Shakura, N

    2015-01-01T23:59:59.000Z

    Using the anelastic approximation of linearised hydrodynamic equations, we investigate the development of axially symmetric small perturbations in thin Keplerian discs. The sixth-order dispersion equation is derived and numerically solved for different values of relevant physical parameters (viscosity, heat conductivity, disc semi-thickness and vertical structure). The analysis reveals the appearance of two overstable modes which split out from the classical Rayleigh inertial modes in a wide range of the parameters in both ionized and neutral gases. These modes have a viscous-convective nature and can serve as a seed for turbulence in astrophysical discs even in the absence of magnetic fields.

  19. A collagen-GAG matrix for the growth of intervertebral disc tissue

    E-Print Network [OSTI]

    Hastreiter, Dawn (Dawn Marie), 1973-

    2002-01-01T23:59:59.000Z

    Intervertebral disc (IVD) degeneration and herniation is a significant problem, more so in the aviation field. The IVD also changes during spaceflight. Current treatments for IVD problems can have unfavorable long-term ...

  20. Retinal imaging tool for assessment of the parapapillary atrophy and the optic disc 

    E-Print Network [OSTI]

    Lu, Cheng-Kai

    2012-11-29T23:59:59.000Z

    Ophthalmic diseases such as glaucoma are associated with progressive changes in the structure of the optic disc (OD) and parapapillary atrophy (PPA). These structural changes may therefore have relevance to other systemic ...

  1. E-Print Network 3.0 - accretion disc variability Sample Search...

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

    370, L61L65 (2006) doi:10.1111j.1745-3933.2006.00189.x The late time evolution of gamma-ray bursts: ending hyperaccretion Summary: of GRBs. Key words: accretion, accretion discs -...

  2. Spectra of disc operator for twisted acceleration-enlarged Newton-Hooke space-times

    E-Print Network [OSTI]

    Marcin Daszkiewicz

    2011-01-10T23:59:59.000Z

    The time-dependent spectra of disc area operator for twisted acceleration-enlarged Newton-Hooke space-times are derived. It is demonstrated that the corresponding area quanta are expanding or oscillating in time.

  3. NDE1 in the DISC1 pathway: interactions of schizophrenia-related proteins 

    E-Print Network [OSTI]

    Bradshaw, Nicholas James

    2009-01-01T23:59:59.000Z

    The Disrupted-In-Schizophrenia 1 (DISC1) gene is one of the most established risk genes for psychiatric illness currently being studied, having originally been identified as being directly disrupted by a balanced chromosomal ...

  4. Dynamics of perturbation modes in protoplanetary discs : new effects of self-gravity and velocity shear 

    E-Print Network [OSTI]

    Mamatsashvili, George

    2011-06-27T23:59:59.000Z

    Protoplanetary discs, composed of gas and dust, usually surround young stellar objects and serve two main purposes: they determine the accretion of matter onto the central object and also represent sites of planet ...

  5. Quantum McKay correspondence for disc invariants of toric Calabi-Yau 3-orbifolds

    E-Print Network [OSTI]

    Hua-Zhong Ke; Jian Zhou

    2014-10-16T23:59:59.000Z

    We announce a result on quantum McKay correspondence for disc invariants of outer legs in toric Calabi-Yau 3-orbifolds, and illustrate our method in a special example $[\\mathbb C^3 /\\mathbb Z_5 (1, 1, 3)]$.

  6. Spectral Evolution of the Continuum and Disc Line in Dipping in GRO J1655-40

    E-Print Network [OSTI]

    M. Balucinska-Church

    2001-01-22T23:59:59.000Z

    The discovery is reported of emission features in the X-ray spectrum of GRO J1655-40 obtained using Rossi-XTE on 1997, Feb 26. The features have been fitted firstly by two Gaussian lines, which in four spectra have average energies of 5.85+/-0.08 keV and 7.32+/-0.13 keV, strongly suggestive that these are the red- and blueshifted wings of an iron disc line from material with velocity ~0.33 c. The blue wing is apparently less bright than expected for a disc line subject to Doppler boosting, however, known absorption in the spectrum of GRO J1655-40 at energies between ~7 and 8 keV can reduce the apparent brightness of the blue wing. The spectra have also been fitted well using the full relativistic disc line model of Laor, plus an absorption line. This gives a restframe energy between 6.4 and 6.8 keV indicating that the line is from highly ionized iron K_alpha. The Laor model also shows that the line originates at radii extending from ~10 Schwarzschild radii (r_S) outwards. The line is direct evidence for the black hole nature of the compact object. The continuum is well described by dominant disc blackbody emission plus Comptonized emission. During dipping, spectral evolution is well modelled by allowing progressive covering of the disc blackbody and simple absorption of the Comptonized emission showing that the thermal emission is more extended. Acceptable fits are only obtained by including the disc line in the covering term, indicating that it originates in the same inner disc region as the thermal continuum. Dip ingress times and durations are used to provide the radius of the disc blackbody emitter as 170-370 r_S, and the radius of the absorber.

  7. Hard discs under steady shear: comparison of Brownian dynamics simulations and mode coupling theory

    E-Print Network [OSTI]

    O. Henrich; F. Weysser; M. E. Cates; M. Fuchs

    2010-01-19T23:59:59.000Z

    Brownian dynamics simulations of bidisperse hard discs moving in two dimensions in a given steady and homogeneous shear flow are presented close to and above the glasstransition density. The stationary structure functions and stresses of shear-melted glass are compared quantitatively to parameter-free numerical calculations of monodisperse hard discs using mode coupling theory within the integration through transients framework. Theory qualitatively explains the properties of the yielding glass but quantitatively overestimatesthe shear-driven stresses and structural anisotropies.

  8. Conference Call and Web Chat on Small Businesses and Government...

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

    Conference Call and Web Chat on Small Businesses and Government Contracting Conference Call and Web Chat on Small Businesses and Government Contracting March 27, 2012 - 2:15pm...

  9. Secular resonant dressed orbital diffusion II : application to an isolated self similar tepid galactic disc

    E-Print Network [OSTI]

    Fouvry, Jean-Baptiste

    2015-01-01T23:59:59.000Z

    The main orbital signatures of the secular evolution of an isolated self-gravitating stellar Mestel disc are recovered using a dressed Fokker-Planck formalism in angle-action variables. The shot-noise-driven formation of narrow ridges of resonant orbits is recovered in the WKB limit of tightly wound transient spirals, for a tepid Toomre-stable tapered disc. The relative effect of the bulge, the halo, the disc temperature and the spectral properties of the shot noise are investigated in turn. For such galactic discs all elements seem to impact the locus and direction of the ridge. For instance, when the halo mass is decreased, we observe a transition between a regime of heating in the inner regions of the disc through the inner Lindblad resonance to a regime of radial migration of quasi-circular orbits via the corotation resonance in the outer part of the disc. The dressed secular formalism captures both the nature of collisionless systems (via their natural frequencies and susceptibility), and their nurture v...

  10. Searching for the metal-weak thick disc in the solar neighbourhood

    E-Print Network [OSTI]

    Bacham E. Reddy; David L. Lambert

    2008-09-05T23:59:59.000Z

    An abundance analysis is presented of 60 metal-poor stars drawn from catalogues of nearby stars provided by Ariyanto et al. (2005) and Schuster et al. (2006). In an attempt to isolate a sample of metal-weak thick disc stars, we applied the kinematic criteria $V_{\\rm rot} \\geq 100$ km s$^{-1}$, $|U_{LSR}| \\leq 140$ km s$^{-1}$, and $|W_{LSR}| \\leq 100$ km s$^{-1}$. Fourteen stars satisfying these criteria and having [Fe/H] $\\leq -1.0$ are included in the sample of 60 stars. Eight of the 14 have [Fe/H] $\\geq -1.3$ and may be simply thick disc stars of slightly lower than average [Fe/H]. The other six have [Fe/H] from -1.3 to -2.3 and are either metal-weak thick disc stars or halo stars with kinematics mimicking those of the thick disc. The sample of 60 stars is completed by eight thick disc stars, 20 stars of a hybrid nature (halo or thick disc stars), and 18 stars with kinematics distinctive of the halo.

  11. One-armed spirals in locally isothermal, radially structured self-gravitating discs

    E-Print Network [OSTI]

    Lin, Min-Kai

    2015-01-01T23:59:59.000Z

    We describe a new mechanism that leads to the destabilisation of non-axisymmetric waves in astrophysical discs with an imposed radial temperature gradient. This might apply, for example, to the outer parts of protoplanetary discs. We use linear density wave theory to show that non-axisymmetric perturbations generally do not conserve their angular momentum in the presence of a forced temperature gradient. This implies an exchange of angular momentum between linear perturbations and the background disc. In particular, when the disturbance is a low-frequency trailing wave and the disc temperature decreases outwards, this interaction is unstable and leads to the growth of the wave. We demonstrate this phenomenon through numerical hydrodynamic simulations of locally isothermal discs in 2D using the FARGO code and in 3D with the ZEUS-MP and PLUTO codes. We consider radially structured discs with a self-gravitating region which remains stable in the absence of a temperature gradient. However, when a temperature grad...

  12. The Gaia-ESO Survey: Insights on the inner-disc evolution from open clusters

    E-Print Network [OSTI]

    Magrini, L; Donati, P; Bragaglia, A; Adibekyan, V; Romano, D; Smiljanic, R; Blanco-Cuaresma, S; Tautvaisiene, G; Friel, E; Overbeek, J; Jacobson, H; Cantat-Gaudin, T; Vallenari, A; Sordo, R; Pancino, E; Geisler, D; Roman, I San; Villanova, S; Casey, A; Hourihane, A; Worley, C C; Francois, P; Gilmore, G; Bensby, T; Flaccomio, E; Korn, A J; Recio-Blanco, A; Carraro, G; Costado, M T; Franciosini, E; Heiter, U; Jofree, P; Lardo, C; de Laverny, P; Monaco, L; Morbidelli, L; Sacco, G; Sousa, S G; Zaggia, S

    2015-01-01T23:59:59.000Z

    Context. The inner disc, linking the thin disc with the bulge, has been somehow neglected in the past because of intrinsic difficulties in its study, due, e.g., to crowding and high extinction. Open clusters located in the inner disc are among the best tracers of its chemistry at different ages and distances. Aims. We analyse the chemical patterns of four open clusters located within 7 kpc of the Galactic Centre and of field stars to infer the properties of the inner disc with the Gaia-ESO survey idr2/3 data release. Methods. We derive the parameters of the newly observed cluster, Berkeley 81, finding an age of about 1 Gyr and a Galactocentric distance of 5.4 kpc. We construct the chemical patterns of clusters and we compare them with those of field stars in the Solar neighbourhood and in the inner-disc samples. Results. Comparing the three populations we observe that inner-disc clusters and field stars are both, on average, enhanced in [O/Fe], [Mg/Fe] and [Si/Fe]. Using the idr2/3 results of M67, we estimate...

  13. Liberation of specific angular momentum through radiation and scattering in relativistic black hole accretion discs

    E-Print Network [OSTI]

    Adam R. H. Stevens

    2015-02-26T23:59:59.000Z

    A key component of explaining the array of galaxies observed in the Universe is the feedback of active galactic nuclei, each powered by a massive black hole's accretion disc. For accretion to occur, angular momentum must be lost by that which is accreted. Electromagnetic radiation must offer some respite in this regard, the contribution for which is quantified in this paper using solely general relativity under the thin-disc regime. Herein, I calculate extremised situations where photons are entirely responsible for energy removal in the disc and then extend and relate this to the standard relativistic accretion disc outlined by Novikov & Thorne that includes the effect of viscosity. While there is potential for the contribution of angular-momentum removal from photons to be >~1% out to ~10^4 Schwarzschild radii, especially if the disc is irradiated and is liberated of angular momentum through scattering, it is more likely of order 10^2 Schwarzschild radii if thermal emission from the disc itself is stronger. Near the horizons of fast-spinning black holes, these modes of angular-momentum liberation become dominant.

  14. alarm call recognition: Topics by E-print Network

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

    different call recognition mechanisms. Key words: acoustic communication, temporal pattern recognition, hearing, amplitude modulation, phonotaxis, Neoconocephalus. Joshua A....

  15. Eurospeech 2001 -Scandinavia OASIS Natural Language Call Steering Trial

    E-Print Network [OSTI]

    Fosler-Lussier, Eric

    Eurospeech 2001 - Scandinavia OASIS Natural Language Call Steering Trial Peter J Durston 1 , Mark's call steering banking trials [2]. This paper describes a recent trial of the OASIS call steering system on live traffic from a UK operator centre. This trial is part of an ongoing investigation under the OASIS

  16. Emergent Mesoscale Phenomena in Magnetized Accretion Disc Turbulence

    E-Print Network [OSTI]

    Simon, Jacob B; Armitage, Philip J

    2012-01-01T23:59:59.000Z

    We study how the structure and variability of magnetohydrodynamic (MHD) turbulence in accretion discs converge with domain size. Our results are based on a series of vertically stratified local simulations, computed using the Athena code, that have fixed spatial resolution, but varying radial and azimuthal extent (from \\Delta R = 0.5H to 16H, where H is the vertical scale height). We show that elementary local diagnostics of the turbulence, including the Shakura-Sunyaev {\\alpha} parameter, the ratio of Maxwell stress to magnetic energy, and the ratio of magnetic to fluid stresses, converge to within the precision of our measurements for spatial domains of radial size Lx \\geq 2H. We obtain {\\alpha} = 0.02-0.03, consistent with recent results. Very small domains (Lx = 0.5H) return anomalous results, independent of spatial resolution. The convergence with domain size is only valid for a limited set of diagnostics: larger spatial domains admit the emergence of dynamically important mesoscale structures. In our la...

  17. Measuring the configurational temperature of a binary disc packing

    E-Print Network [OSTI]

    Song-Chuan Zhao; Matthias Schröter

    2014-06-20T23:59:59.000Z

    Jammed packings of granular materials differ from systems normally described by statistical mechanics in that they are athermal. In recent years a statistical mechanics of static granular media has emerged where the thermodynamic temperature is replaced by a configurational temperature X which describes how the number of mechanically stable configurations depends on the volume. Four different methods have been suggested to measure X. Three of them are computed from properties of the Voronoi volume distribution, the fourth takes into account the contact number and the global volume fraction. This paper answers two questions using experimental binary disc packings: First we test if the four methods to measure compactivity provide identical results when applied to the same dataset. We find that only two of the methods agree quantitatively. Secondly, we test if X is indeed an intensive variable; this becomes true only for samples larger than roughly 200 particles. This result is shown to be due to recently found correlations between the particle volumes [Zhao et al., Europhys. Lett., 2012, 97, 34004].

  18. Survival and Structure of Dusty Vortices in Protoplanetary Discs

    E-Print Network [OSTI]

    Crnkovic-Rubsamen, Ivo; Stone, James M

    2015-01-01T23:59:59.000Z

    We have studied the impact of dust feedback on the survival and structure of vortices in protoplanetary discs using 2-D shearing box simulations with Lagrangian dust particles. We consider dust with a variety of sizes (stopping time $t_s = 10^{-2}\\Omega^{-1} - 10^{2}\\Omega^{-1}$, from fully coupled with the gas to the decoupling limit. We find that a vortex is destroyed by dust feedback when the total dust-to-gas mass ratio within the vortex is larger than 30-50%, independent of the dust size. The dust distribution can still be asymmetric in some cases after the vortex has been destroyed. With smaller amounts of dust, a vortex can survive for at least 100 orbits, and the maximum dust surface density within the vortex can be more than 100 times larger than the gas surface density, potentially facilitating planetesimal formation. On the other hand, in these stable vortices, small ($t_s \\Omega^{-1}$) dust grains concentrate differently and affect the gas dynamics in different ways. The distribution of large dus...

  19. Jammed frictionless discs: connecting local and global response

    E-Print Network [OSTI]

    Wouter G. Ellenbroek; Martin van Hecke; Wim van Saarloos

    2009-11-04T23:59:59.000Z

    By calculating the linear response of packings of soft frictionless discs to quasistatic external perturbations, we investigate the critical scaling behavior of their elastic properties and non-affine deformations as a function of the distance to jamming. Averaged over an ensemble of similar packings, these systems are well described by elasticity, while in single packings we determine a diverging length scale $\\ell^*$ up to which the response of the system is dominated by the local packing disorder. This length scale, which we observe directly, diverges as $1/\\Delta z$, where $\\Delta z$ is the difference between contact number and its isostatic value, and appears to scale identically to the length scale which had been introduced earlier in the interpretation of the spectrum of vibrational modes. It governs the crossover from isostatic behavior at the small scale to continuum behavior at the large scale; indeed we identify this length scale with the coarse graining length needed to obtain a smooth stress field. We characterize the non-affine displacements of the particles using the \\emph{displacement angle distribution}, a local measure for the amount of relative sliding, and analyze the connection between local relative displacements and the elastic moduli.

  20. The effects of X-ray photoionization and heating on the structure of circumstellar discs

    E-Print Network [OSTI]

    R. D. Alexander; C. J. Clarke; J. E. Pringle

    2004-06-29T23:59:59.000Z

    We present the results of a theoretical study investigating the effects of photoionization and heating by X-rays on discs around low-mass stars. In particular we address the question of whether or not X-rays can drive a disc wind. First, we construct a 1-dimensional ``quasi-hydrostatic'' model, which solves for the vertical structure introduced by X-ray heating. We consider uniform X-ray illumination of the disc, but the X-ray fluxes required to heat the disc significantly are much greater than those seen by recent observations. When the model is extended to consider heating from a central X-ray source we find that the 1-dimensional model is only valid very close to the star. We extend our analysis to consider a simple 2-dimensional model, treating the disc as a two-layered structure and solving for its density profile self-consistently. For T Tauri stars we are able to set a crude upper limit on the mass-loss rate that can be driven by X-ray photoevaporation, with a value of ~10^-13 g/cm^2/s. Our model is designed to maximise this value, and most likely over-estimates it significantly. However we still find a mass-loss rate which is less than that found in studies of ultraviolet photoevaporation. We conclude that in the presence of a significant UV field, X-ray driven disc winds are unlikely to play a significant role in the evolution of discs around low-mass stars.

  1. Evolution of binary black holes in self gravitating discs: dissecting the torques

    E-Print Network [OSTI]

    Constanze Roedig; Alberto Sesana; Massimo Dotti; Jorge Cuadra; Pau Amaro-Seoane; Francesco Haardt

    2012-08-14T23:59:59.000Z

    We study the interplay between gas accretion and gravity torques in changing a binary elements and its total angular momentum (L) budget. Especially, we analyse the physical origin of the gravity torques (T_g) and their location within the disc. We analyse 3D SPH simulations of the evolution of initially quasi-circular massive black hole binaries (BHBs) residing in the central hollow of massive self-gravitating circumbinary discs. We use different thermodynamics within the cavity and for the numerical size of the black holes to show that (i) the BHB eccentricity growth found previously is a general result, independent of the accretion and the adopted thermodynamics; (ii) the semi-major axis decay depends both on the T_g and on the interplay with the disc-binary L-transfer due to accretion; (iii) the spectral structure of the T_g is predominately caused by disc edge overdensities and spiral arms developing in the body of the disc and, in general, does not reflect directly the period of the binary; (iv) the net T_g changes sign across the BHB corotation radius. We quantify the relative importance of the two, which appear to depend on the thermodynamical properties of the instreaming gas, and which is crucial in assessing the disc-binary L-transfer; (v) the net torque manifests as a purely kinematic (non-resonant) effect as it stems from the cavity, where the material flows in and out in highly eccentric orbits. Both accretion onto the black holes and the interaction with gas streams inside the cavity must be taken into account to assess the fate of the BHB. Moreover, the total torque exerted by the disc affects L(BHB) by changing all the elements (mass, mass ratio, eccentricity, semimajor axis) of the BHB. Common prescriptions equating tidal torque to semi-major axis shrinking might therefore be poor approximations for real astrophysical systems.

  2. Accretion Disc Turbulence and the X-Ray Power Spectra of Black Hole High States

    E-Print Network [OSTI]

    Michael A. Nowak; Robert V. Wagoner

    1994-10-06T23:59:59.000Z

    The high state of black hole candidates is characterized by a quasi- thermal emission component at $kT \\sim 1$ keV. In addition, this state tends to have very low variability which indicates that it is relatively stable, at least on {\\it short} time scales. Most models of the high state imply that the bulk of the emission comes from an optically thick accretion disc; therefore, this state may be an excellent laboratory for testing our ideas about the physics of accretion discs. In this work we consider the implications of assuming that accretion disc viscosity arises from some form of turbulence. Specifically, we consider the simple case of three dimensional hydrodynamic turbulence. It is found that the coupling of such turbulence to acoustic modes in the disc can alter the disc emission. We calculate the amplitude and frequencies of this modulation, and we express our results in terms of the X-ray power spectral density. We compare our calculations with observations of the black hole candidate GS 1124-683, and show that for certain parameters we can reproduce some of the high frequency power. We then briefly explore mechanisms for producing the low frequency power, and note the difficulty that a single variability mechanism has in reproducing the full range of observed variability. In addition, we outline ways in which future spacecraft missions -- such as USA and XTE -- can further constrain our model, especially at frequencies above $\\sim 10^2$ Hz.

  3. On the migration of two planets in a disc and the formation of mean motion resonances

    E-Print Network [OSTI]

    Migaszewski, Cezary

    2015-01-01T23:59:59.000Z

    We study the dynamics of a system of two super-Earths embedded in a protoplanetary disc. Depending on the disc parameters, planets' masses and positions in the disc, the migration of a planet can be inward or outward and the migration of a two-planet system can be convergent or divergent. The convergent migration means that the period ratio P2/P1 decreases in time. In such a case mean motion resonance (MMR) can be formed when the period ratio reaches a resonant value of a first order MMR (p+1)/p, where p is a small integer. When the divergent migration occurs, P2/P1 increases in time and a system initially close to MMR moves away from the resonance. We build a simple model of an irradiated viscous disc and use analytical prescriptions for the planet-disc interactions. We performed 3500 simulations of the migration of two-planet systems with various masses and initial orbits. We found that approximately half of the systems end up as configurations involved in one of the first order MMRs such as 2:1, 3:2, 4:3 a...

  4. The evolution of disc galaxies with and without classical bulges since z~1

    E-Print Network [OSTI]

    Sachdeva, Sonali; Saha, Kanak; Singh, Harinder P

    2015-01-01T23:59:59.000Z

    Establishing the relative role of internally and externally driven mechanisms responsible for disc and bulge growth is essential to understand the evolution of disc galaxies. In this context, we have studied the physical properties of disc galaxies without classical bulges in comparison to those with classical bulges since z~0.9. Using images from the Hubble Space Telescope and Sloan Digital Sky Survey, we have computed both parametric and non-parametric measures, and examined the evolution in size, concentration, stellar mass, effective stellar mass density and asymmetry. We find that both disc galaxies with and without classical bulges have gained more than 50% of their present stellar mass over the last ~8 Gyrs. Also, the increase in disc size is found to be peripheral. While the average total (Petrosian) radius almost doubles from z~0.9 to z~0, the average effective radius undergoes a marginal increase in comparison. Additionally, increase in the density of the inner region is evident through the evolutio...

  5. Message from Hugh Montgomery: Call for FY16 LDRD Proposals |...

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

    Message from Hugh Montgomery: Call for FY16 LDRD Proposals An important element of Jefferson Lab's Strategic Plan is the implementation of a Laboratory Directed Research and...

  6. President Reagan Calls for a National Spent Fuel Storage Facility...

    National Nuclear Security Administration (NNSA)

    Reagan Calls for a National Spent Fuel Storage Facility | National Nuclear Security Administration Facebook Twitter Youtube Flickr RSS People Mission Managing the Stockpile...

  7. EM SSAB Chairs Conference Calls | Department of Energy

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

    March 27, 2008 EM SSAB Conference Calls - March 27, 2008 Minutes and highlights of the Environmental Management (EM) Site Specific Advisory Board's (SSAB) Bi-Monthly conference...

  8. administrator calls riga: Topics by E-print Network

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

    Gerbeth; Thomas Gundrum; Frank Stefani; Michael Christen; Heiko Hnel; Gotthard Will 1999-12-13 10 Policy:OnCall Arrangements Mathematics Websites Summary: to staff in the...

  9. Program Sustainability Peer Exchange Call: Transitioning to a...

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

    Program Sustainability Peer Exchange Call: Transitioning to a Utility Funded Program Environment: What Do I Need to Know? (January 17, 2013) Program Sustainability Peer Exchange...

  10. Better Buildings Neighborhood Program Peer Exchange Call: Program...

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

    23, 2013 Better Buildings Neighborhood Program Peer Exchange Call: Program Sustainability Mastermind Session on Combining Energy Efficiency and Health Services, featuring Host: Tim...

  11. Minutes: EM SSAB Chairs Budget Conference Call - October 5, 2010

    Office of Environmental Management (EM)

    Budget Conference Call October 5, 2010 Participants Chairs Representatives: Site Support Staff: Idaho R.D. Maynard Nevada Oak Ridge Jeff Miller Kelly Snyder Pete Osborne Paducah...

  12. Magnetic Turbulence and Thermodynamics in the Inner Region of Protoplanetary Discs

    E-Print Network [OSTI]

    Hirose, Shigenobu

    2015-01-01T23:59:59.000Z

    Using radiation magnetohydrodynamics simulations with realistic opacities and equation of state, and zero net magnetic flux, we have explored thermodynamics in the inner part of protoplanetary discs where magnetic turbulence is expected. The thermal equilibrium curve consists of the upper, lower, and middle branches. The upper (lower) branch corresponds to hot (cool) and optically very (moderately) thick discs, respectively, while the middle branch is characterized by convective energy transport near the midplane. Convection is also the major energy transport process near the low surface density end of the upper branch. There, convective motion is fast with Mach numbers reaching $\\gtrsim 0.01$, and enhances both magnetic turbulence and cooling, raising the ratio of vertically-integrated shear stress to vertically-integrated pressure by a factor of several. This convectively enhanced ratio seems a robust feature in accretion discs having an ionization transition. We have also examined causes of the S-shaped th...

  13. On the black hole limit of rotating discs of charged dust

    E-Print Network [OSTI]

    Martin Breithaupt; Yu-Chun Liu; Reinhard Meinel; Stefan Palenta

    2015-05-04T23:59:59.000Z

    Investigating the rigidly rotating disc of dust with constant specific charge, we find that it leads to an extreme Kerr-Newman black hole in the ultra-relativistic limit. A necessary and sufficient condition for a black hole limit is, that the electric potential in the co-rotating frame is constant on the disc. In that case certain other relations follow. These relations are reviewed with a highly accurate post-Newtonian expansion. Remarkably it is possible to survey the leading order behaviour close to the black hole limit with the post-Newtonian expansion. We find that the disc solution close to that limit can be approximated very well by a "hyper\\-extreme" Kerr-Newman solution with the same gravitational mass, angular momentum and charge.

  14. The structure and radiation spectra of illuminated accretion discs in AGN. I. Moderate illumination

    E-Print Network [OSTI]

    A. Ró?a?ska; A. -M. Dumont; B. Czerny; S. Collin

    2002-02-12T23:59:59.000Z

    We present detailed computations of the vertical structure of an accretion disc illuminated by hard X-ray radiation with the code {\\sc titan-noar} suitable for Compton thick media. The energy generated via accretion is dissipated partially in the cold disc as well as in the X-ray source. We study the differences between the case where the X-ray source is in the form of a lamp post above the accretion disc and the case of a heavy corona. We consider radiative heating via Comptonization together with heating via photo-absorption on numerous heavy elements as carbon, oxygen, silicon, iron. The transfer in lines is precisely calculated. A better description of the heating/cooling through the inclusion of line transfer, a correct description of the temperature in the deeper layers, a correct description of the entire disc vertical structure, as well as the study of the possible coronal pressure effect, constitute an improvement in comparison to previous works. We show that exact calculations of hydrostatic equilibrium and determination of the disc thickness has a crucial impact on the optical depth of the hot illuminated zone. We assume a moderate illumination where the viscous flux equals the X-ray radiation flux. A highly ionized skin is created in the lamp post model, with the outgoing spectrum containing many emission lines and ionization edges in emission or absorption in the soft X-ray domain, as well as an iron line at $\\sim 7 $ keV consisting of a blend of low ionization line from the deepest layers and hydrogen and helium like resonance line from the upper layers, and almost no absorption edge, contrary to the case of a slab of constant density.A full heavy corona completely suppresses the highly ionized zone on the top of the accretion disc and in such case the spectrum is featureless.

  15. Mentored Clinical Research Training Program (MCRTP) Call for Applications

    E-Print Network [OSTI]

    Leistikow, Bruce N.

    Mentored Clinical Research Training Program (MCRTP) Call for Applications Deadline to submit to announce the annual call for applications for the Mentored Clinical Research Training Program (MCRTP of continuing coursework and mentored research, ending in June 2016. Selected scholars will need a 70% time

  16. The Infant & Toddler Assessment Clinic When: Please call for appointment.

    E-Print Network [OSTI]

    The Infant & Toddler Assessment Clinic When: Please call for appointment. Evaluation is about 2 hrs ­ there is no charge Where: In Eugene Clinical Services Building University of Oregon 901 E 18th St. Call: Toolie Kable Toddler Assessment Clinic Research study: eirb #000958 Principal Investigator: Robert Nickel MD Do You

  17. Methods for Saving and Restoring Register Values across Function Calls

    E-Print Network [OSTI]

    Whalley, David

    Methods for Saving and Restoring Register Values across Function Calls JACK W. DAVIDSON AND DAVID B The method used to save and restore the values of registers across function calls can affect performance that empirically evaluated six different schemes for saving and restoring registers on CISC machines. The methods

  18. W.C. Heraeus GmbH and its activities regarding large grain Niobium Discs

    SciTech Connect (OSTI)

    Spaniol, Bernd [W.C.Heraeus GmbH, Engineered Material Division, Heraeusstrasse 12-14, 63450 Hanau (Germany)

    2007-08-09T23:59:59.000Z

    W.C. Heraeus is one of the leading companies in the field of precious and refractory metals. The refractory metals activities have been started in 1940. W.C. Heraeus is one of the qualified suppliers for high pure Niobium for the use in high-frequency-super-conducting cavities. The latest activities in that field are the development of a stable Electron-Beam-Melting and reliable cutting processes to produce large grain Niobium discs directly cut from the Ingot in an industrial scale. The first cavities out of these discs have been tested and are showing excellent magnetic properties.

  19. The Gaia-ESO Survey: a quiescent Milky Way with no significant dark/stellar accreted disc

    E-Print Network [OSTI]

    Ruchti, G R; Feltzing, S; Serenelli, A M; McMillan, P; Lind, K; Bensby, T; Bergemann, M; Asplund, M; Vallenari, A; Flaccomio, E; Pancino, E; Korn, A J; Recio-Blanco, A; Bayo, A; Carraro, G; Costado, M T; Damiani, F; Heiter, U; Hourihane, A; Jofre, P; Kordopatis, G; Lardo, C; de Laverny, P; Monaco, L; Morbidelli, L; Sbordone, L; Worley, C C; Zaggia, S

    2015-01-01T23:59:59.000Z

    According to our current cosmological model, galaxies like the Milky Way are expected to experience many mergers over their lifetimes. The most massive of the merging galaxies will be dragged towards the disc-plane, depositing stars and dark matter into an accreted disc structure. In this work, we utilize the chemo-dynamical template developed in Ruchti et al. to hunt for accreted stars. We apply the template to a sample of 4,675 stars in the third internal data release from the Gaia-ESO Spectroscopic Survey. We find a significant component of accreted halo stars, but find no evidence of an accreted disc component. This suggests that the Milky Way has had a rather quiescent merger history since its disc formed some 8-10 billion years ago and therefore possesses no significant dark matter disc.

  20. Energetics of star-disc encounters in the non-linear regime

    E-Print Network [OSTI]

    S. M. Hall; C. J. Clarke; J. E. Pringle

    1995-10-31T23:59:59.000Z

    We investigate the response of a circumstellar accretion disc to the fly-by of a perturbing mass on a parabolic orbit. The energy and angular momentum transferred during the encounter are calculated using a reduced three-body method. In almost all close encounters the energy and angular momentum transfer is dominated by disc material becoming unbound from the system, with the contributions from close disc particle -- star encounters being significant. For more distant encounters with some prograde element to the motion the disc material loses energy and angular momentum to the perturber's orbit through a resonance feature. The magnitude of the energy transfer calculated in our simulations is greater than that of the binding energy of material exterior to periastron by a factor of two in the prograde case, and up to a factor of five in the case of the retrograde encounter. The destructive nature of the encounters indicates that a non-linear treatment is essential in all but the most distant encounters.

  1. Anisotropic radiation from accretion disc-coronae in active galactic nuclei

    E-Print Network [OSTI]

    Xu, Ya-Di

    2015-01-01T23:59:59.000Z

    In the unification scheme of active galactic nuclei (AGN), Seyfert 1s and Seyfert 2s are intrinsically same, but they are viewed at different angles. However, the Fe K\\alpha emission line luminosity of Seyfert 1s was found in average to be about twice of that of Seyfert 2s at given X-ray continuum luminosity in the previous work (Ricci et al. 2014). We construct an accretion disc-corona model, in which a fraction of energy dissipated in the disc is extracted to heat the corona above the disc. The radiation transfer equation containing Compton scattering processes is an integro-differential equation, which is solved numerically for the corona with a parallel plane geometry. We find that the specific intensity of X-ray radiation from the corona changes little with the viewing angle \\theta when \\theta is small (nearly face-on), and it is sensitive to \\theta if the viewing angle is large (\\theta> 40 degrees). The radiation from the cold disc, mostly in infrared/optical/UV bands, is almost proportional to cos\\thet...

  2. Internal Alignments of Red Versus Blue Discs in Dark Matter Halos

    E-Print Network [OSTI]

    Debattista, Victor P; Roskar, Rok; Quinn, Thomas; Moore, Ben; Cole, David R

    2015-01-01T23:59:59.000Z

    Large surveys have shown that red galaxies are preferentially aligned with their halos while blue galaxies have a more isotropic distribution. Since halos generally align with their filaments this introduces a bias in the measurement of the cosmic shear from weak lensing. It is therefore vitally important to understand why this difference arises. We explore the stability of different disc orientations within triaxial halos. We show that, in the absence of gas, the disc orientation is most stable when its spin is along the minor axis of the halo. Instead when gas cools onto a disc it is able to form in almost arbitrary orientation, including off the main planes of the halo (but avoiding an orientation perpendicular to the halo's intermediate axis). Substructure helps gasless galaxies reach alignment with the halo faster, but have less effect on galaxies when gas is cooling onto the disc. Our results provide a novel and natural interpretation for why red, gas poor galaxies are preferentially aligned with their ...

  3. The local star formation history of the thin disc derived from kinematic data

    E-Print Network [OSTI]

    A. Just; H. Jahreiss

    2010-12-27T23:59:59.000Z

    We present an evolutionary disc model for the thin disc in the solar cylinder based on a continuous star formation history and a continuous dynamical heating of the stellar subpopulations. The vertical distribution of the stellar subpopulations are calculated self-consistently in dynamical equilibrium. The SFR and AVR of the stellar subpopulations are determined by fitting the velocity distribution functions of main sequence stars. The SFR shows a maximum 10 Gyr ago declining by a factor of 10 until present time. A constant SFR can be ruled out. The velocity dispersion of the stellar subpopulations increase with age according to a power law with index 0.375. The new scale heights lead to a best fit IMF with power-law indices of 1.5 below and 4.0 above 1.6 Msun, which has no kink around 1 Msun. Including a thick disc component results in slight variations of the thin disc properties, but has a negligible influence on the SFR. A variety of predictions are made concerning the number density, age and metallicity distributions of stellar subpopulations as a function of z above the galactic plane.

  4. Searching for signatures of planet formation in stars with circumstellar debris discs

    E-Print Network [OSTI]

    Maldonado, J; Villaver, E; Montesinos, B; Mora, A

    2015-01-01T23:59:59.000Z

    (Abridged) Tentative correlations between the presence of dusty debris discs and low-mass planets have been presented. In parallel, detailed chemical abundance studies have reported different trends between samples of planet and non-planet hosts. We determine in a homogeneous way the metallicity, and abundances of a sample of 251 stars including stars with known debris discs, with debris discs and planets, and only with planets. Stars with debris discs and planets have the same [Fe/H] behaviour as stars hosting planets, and they also show a similar -Tc trend. Different behaviour in the -Tc trend is found between the samples of stars without planets and the samples of planet hosts. In particular, when considering only refractory elements, negative slopes are shown in cool giant planet hosts, whilst positive ones are shown in stars hosting low-mass planets. Stars hosting exclusively close-in giant planets show higher metallicities and positive -Tc slope. A search for correlations between the -Tc slopes and the ...

  5. The structure and radiation spectra of illuminated accretion discs in AGN. I. Moderate illumination

    E-Print Network [OSTI]

    Rózanska, A R; Czerny, B; Collin, S

    2002-01-01T23:59:59.000Z

    We present detailed computations of the vertical structure of an accretion disc illuminated by hard X-ray radiation with the code {\\sc titan-noar} suitable for Compton thick media. The energy generated via accretion is dissipated partially in the cold disc as well as in the X-ray source. We study the differences between the case where the X-ray source is in the form of a lamp post above the accretion disc and the case of a heavy corona. We consider radiative heating via Comptonization together with heating via photo-absorption on numerous heavy elements as carbon, oxygen, silicon, iron. The transfer in lines is precisely calculated. A better description of the heating/cooling through the inclusion of line transfer, a correct description of the temperature in the deeper layers, a correct description of the entire disc vertical structure, as well as the study of the possible coronal pressure effect, constitute an improvement in comparison to previous works. We show that exact calculations of hydrostatic equilib...

  6. Gathering data on allegations of sexual abuse made against former disc jockey, Jimmy Savile 

    E-Print Network [OSTI]

    Smith, Mark; Kirkwood, Steve; Llewellyn, Clare

    2014-08-26T23:59:59.000Z

    This paper will report on a collaboration between Social Work and Informatics academics and Library staff at the University. The focus of the work is to secure a data set on allegations of sexual abuse made against the former disc jockey, Jimmy...

  7. DiSC: Benchmarking Secure Chip DBMS Nicolas Anciaux, Luc Bouganim, Philippe Pucheral, and Patrick Valduriez

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    DiSC: Benchmarking Secure Chip DBMS Nicolas Anciaux, Luc Bouganim, Philippe Pucheral, and Patrick irrelevant. The main problem faced by secure chip DBMS designers is to be able to assess various design choices and trade-offs for different applications. Our solution is to use a benchmark for secure chip DBMS

  8. 2D-Zernike polynomials and coherent state quantization of the unit disc

    E-Print Network [OSTI]

    K. Thirulogasanthar; Nasser Saad; G. Honnouvo

    2015-01-07T23:59:59.000Z

    Using the orthonormality of the 2D-Zernike polynomials, reproducing kernels, reproducing kernel Hilbert spaces, and ensuring coherent states attained. With the aid of the so-obtained coherent states, the complex unit disc is quantized. Associated upper symbols, lower symbols and related generalized Berezin transforms also obtained. A number of necessary summation formulas for the 2D-Zernike polynomials proved.

  9. Resonant Trapping in the Galactic Disc and Halo and its Relation with Moving Groups

    E-Print Network [OSTI]

    Moreno, Edmundo; Schuster, William

    2015-01-01T23:59:59.000Z

    With the use of a detailed Milky Way nonaxisymmetric potential, observationally and dynamically constrained, the e?ects of the bar and the spiral arms in the Galaxy are studied in the disc and in the stellar halo. Especially the trapping of stars in the disc and Galactic halo by resonances on the Galactic plane, induced by the Galactic bar, has been analysed in detail. To this purpose, a new method is presented to delineate the trapping regions using empirical diagrams of some orbital properties obtained in the Galactic potential. In these diagrams we plot in the inertial Galactic frame a characteristic orbital energy versus a characteristic orbital angular momentum, or versus the orbital Jacobi constant in the reference frame of the bar, when this is the only nonaxisymmetric component in the Galactic potential. With these diagrams some trapping regions are obtained in the disc and halo using a sample of disc stars and halo stars in the solar neighbourhood. We compute several families of periodic orbits on th...

  10. Tidal disruptions in circumbinary discs (I): Star formation, dynamics, and binary evolution

    E-Print Network [OSTI]

    Pau Amaro-Seoane; Patrick Brem; Jorge Cuadra

    2012-12-11T23:59:59.000Z

    In our current interpretation of the hierarchical structure of the universe it is well established that galaxies collide and merge with each other during their lifetime. If massive black holes (MBHs) reside in galactic centres, we expect them to form binaries in galactic nuclei surrounded by a circumbinary disc. If cooling is efficient enough, the gas in the disc will clump and trigger stellar formation in situ. In this first paper we address the evolution of the binary under the influence of the newly formed stars, which form individually and also clustered. We use SPH techniques to evolve the gas in the circumbinary disc and to study the phase of star formation. When the amount of gas in the disc is negligible, we further evolve the system with a high-accurate direct-summation $N-$body code to follow the evolution of the stars, the innermost binary and tidal disruption events (TDEs). For this, we modify the direct N-body code to (i) include treatment of TDEs and to (ii) include "gas cloud particles" that mimic the gas, so that the stellar clusters do not disolve when we follow their infall on to the MBHs. We find that the amount of stars disrupted by either infalling stellar clusters or individual stars is as large as 10^{-4}/yr per binary, higher than expected for typical galaxies.

  11. Sedimenting discs in a two-dimensional foam I. T. Davies, S. J. Cox

    E-Print Network [OSTI]

    Cox, Simon

    -dimensional foams can be thought of as a monolayer of bubbles squeezed between two glass plates. We choose to probeSedimenting discs in a two-dimensional foam I. T. Davies, S. J. Cox Institute of Mathematics in a dry two-dimensional, monodisperse foam is studied. This, a variation of the classical Stokes

  12. Mentoring African Research in Mathematics (MARM) Call for prospective mentors

    E-Print Network [OSTI]

    Dixon, Peter

    Mentoring African Research in Mathematics (MARM) Call for prospective mentors The London and its teaching in universities in Africa. Four mentoring partnerships are to be awarded, each world, professional mentoring and opportunities for periodic research travel will contribute

  13. Amphibia & Reptilia 27 Distress calls of Mertensiellaluschanifinikensis from

    E-Print Network [OSTI]

    specimens were released after the recordings. Calls were recorded with a Sony Professional Walkman WM-D6C and a Sony ECM-909 mi- crophone (directive angle 120°) at a distance of a few centimetres. Sonagrams were

  14. Extensions of Lo's semiparametric bound for European call options

    E-Print Network [OSTI]

    2006-01-19T23:59:59.000Z

    Jan 19, 2006 ... call option, given up to third-order moment information on the underly- ing asset ...... Assume p(s) has real roots r1 ? r2 ? r3. If a3 > 0 then p(s) ...

  15. Environmentally benign manufacturing of compact disc stampers [Final Phase II report

    SciTech Connect (OSTI)

    None

    1999-07-08T23:59:59.000Z

    Optical data storage is currently a $10B/yr. business. With the introduction of the high capacity Digital Versatile Disc (D/D) as well as the continued growth of CD-Audio and CD-ROM worldwide sales of optical data products as a whole are growing at rate of more than 10% per year. In North America, more than 2.5 billion optical discs will be sold in 1998. By 1999, the numbers of optical discs produced for the North American market will grow to almost three billion. The optical disc manufacturing industry is dominated by Asian and European companies (e.g. Sony of Japan and Philips of Netherlands). Prism Corporation has created a process that could significantly improve US competitiveness in the business of optical disc production. The objectives of the Phase II STTR project were to build and test an ion machining system (IMS) for stamper fabrication, prove overall manufacturing system feasibility by fabrication stampers and replicas, and evaluate alternative materials and alternative process parameters to optimize the process. During tie period of the Phase II project Prism Corporation was able to meet these objectives. In the course of doing so, adjustments had been made to better the project and in turn the final product. An ion machining system was designed and built that produced stampers ready for the molding process. Also, many control steps in the manufacturing process were studied to improve the current process and make it even more compatible with the industry standards, fitting seamlessly into current manufacturing lines.

  16. The response of self-graviting protostellar discs to slow reduction in cooling timescale: the fragmentation boundary revisited

    E-Print Network [OSTI]

    C. Clarke; E. Harper-Clark; G. Lodato

    2007-08-06T23:59:59.000Z

    A number of previous studies of the fragmentation of self-gravitating protostellar discs have modeled radiative cooling with a cooling timescale (t_{cool}) parameterised as a simple multiple (beta_{cool}) of the local dynamical timescale. Such studies have delineated the `fragmentation boundary' in terms of a critical value of beta_{cool} (beta_{crit}), where the disc fragments if beta_{cool} < beta_{crit}. Such an approach however begs the question of how in reality a disc could ever be assembled with beta_{cool} < beta_{crit}. Here we adopt the more realistic approach of gradually reducing beta_{cool}, as might correspond to changes in thermal regime due to secular changes in the disc density profile. We find that when beta_{cool} is gradually reduced (on a timescale longer than t_{cool}), the disc is stabilised against fragmentation, compared with models in which beta_{cool} is reduced rapidly. We therefore conclude that a disc's ability to remain in a self-regulated, self-gravitating state (without fragmentation) is partly dependent on its thermal history, as well as its current cooling rate. Nevertheless, a slow reduction in t_{cool} appears only to lower the fragmentation boundary by about a factor two in t_{cool} and thus only permits maximum alpha values (parameterising the efficiency of angular momentum transfer in the disc) that are about a factor two higher than determined hitherto. Our results therefore do not undermine the notion of a fundamental upper limit to the heating rate that can be delivered by gravitational instabilities before the disc is subject to fragmentation. An important implication of this work, therefore, is that self-gravitating discs can enter into the regime of fragmentation via secular evolution and it is not necessary to invoke rapid (impulsive) events to trigger fragmentation.

  17. Formation of planetary debris discs around white dwarfs II: Shrinking extremely eccentric collisionless rings

    E-Print Network [OSTI]

    Veras, Dimitri; Eggl, Siegfried; Gaensicke, Boris T

    2015-01-01T23:59:59.000Z

    The formation channel of the tens of compact debris discs which orbit white dwarfs (WDs) at a distance of one Solar radius remains unknown. Asteroids that survive the giant branch stellar phases beyond a few au are assumed to be dynamically thrust towards the WD and tidally disrupted within its Roche radius, generating extremely eccentric (e>0.98) rings. Here, we establish that WD radiation compresses and circularizes the orbits of super-micron to cm-sized ring constituents to entirely within the WD's Roche radius. We derive a closed algebraic formula which well-approximates the shrinking time as a function of WD cooling age, the physical properties of the star and the physical and orbital properties of the ring particles. The shrinking timescale increases with both particle size and cooling age, yielding age-dependent WD debris disc size distributions.

  18. AN EMPIRICAL FORMULA FOR THE DISTRIBUTION FUNCTION OF A THIN EXPONENTIAL DISC

    SciTech Connect (OSTI)

    Sharma, Sanjib; Bland-Hawthorn, Joss [Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW 2006 (Australia)

    2013-08-20T23:59:59.000Z

    An empirical formula for a Shu distribution function that reproduces a thin disc with exponential surface density to good accuracy is presented. The formula has two free parameters that specify the functional form of the velocity dispersion. Conventionally, this requires the use of an iterative algorithm to produce the correct solution, which is computationally taxing for applications like Markov Chain Monte Carlo model fitting. The formula has been shown to work for flat, rising, and falling rotation curves. Application of this methodology to one of the Dehnen distribution functions is also shown. Finally, an extension of this formula to reproduce velocity dispersion profiles that are an exponential function of radius is also presented. Our empirical formula should greatly aid the efficient comparison of disc models with large stellar surveys or N-body simulations.

  19. Method and system for assigning a confidence metric for automated determination of optic disc location

    DOE Patents [OSTI]

    Karnowski, Thomas P. (Knoxville, TN); Tobin, Jr., Kenneth W. (Harriman, TN); Muthusamy Govindasamy, Vijaya Priya (Knoxville, TN); Chaum, Edward (Memphis, TN)

    2012-07-10T23:59:59.000Z

    A method for assigning a confidence metric for automated determination of optic disc location that includes analyzing a retinal image and determining at least two sets of coordinates locating an optic disc in the retinal image. The sets of coordinates can be determined using first and second image analysis techniques that are different from one another. An accuracy parameter can be calculated and compared to a primary risk cut-off value. A high confidence level can be assigned to the retinal image if the accuracy parameter is less than the primary risk cut-off value and a low confidence level can be assigned to the retinal image if the accuracy parameter is greater than the primary risk cut-off value. The primary risk cut-off value being selected to represent an acceptable risk of misdiagnosis of a disease having retinal manifestations by the automated technique.

  20. Applying Schwarzschild's orbit superposition method to barred or non-barred disc galaxies

    E-Print Network [OSTI]

    Vasiliev, Eugene

    2015-01-01T23:59:59.000Z

    We present an implementation of the Schwarzschild orbit superposition method which can be used for constructing self-consistent equilibrium models of barred or non-barred disc galaxies, or of elliptical galaxies with figure rotation. This is a further development of the publicly available code SMILE; its main improvements include a new efficient representation of an arbitrary gravitational potential using two-dimensional spline interpolation of Fourier coefficients in the meridional plane, as well as the ability to deal with rotation of the density profile and with multicomponent mass models. We compare several published methods for constructing composite axisymmetric disc--bulge--halo models and demonstrate that our code produces the models that are closest to equilibrium. We also apply it to create models of triaxial elliptical galaxies with cuspy density profiles and figure rotation, and find that such models can be found and are stable over many dynamical times in a wide range of pattern speeds and angula...

  1. Free motion around black holes with discs or rings: between integrability and chaos - I

    E-Print Network [OSTI]

    O. Semerák; P. Suková

    2012-11-17T23:59:59.000Z

    Geodesic dynamics is regular in the fields of isolated stationary black holes. However, due to the presence of unstable periodic orbits, it easily becomes chaotic under various perturbations. Here we examine what amount of chaoticity is induced in Schwarzschild space-time by a presence of an additional source. Following astrophysical motivation, we specifically consider thin rings or discs lying symmetrically around the hole, and describe the total field in terms of exact static and axially symmetric solutions of Einstein's equations. The growth of chaos in time-like geodesic motion is illustrated on Poincar\\'e sections, on time series of position or velocity and their Fourier spectra, and on time evolution of the orbital `latitudinal action'. The results are discussed in dependence on the mass and position of the ring/disc and on geodesic parameters (energy and angular momentum). In the Introduction, we also add an overview of the literature.

  2. A Fragile-Strong Fluid Crossover and Universal Relaxation Times in a Confined Hard Disc Fluid

    E-Print Network [OSTI]

    Mahdi Zaeifi Yamchi; S. S. Ashwin; Richard K. Bowles

    2012-10-22T23:59:59.000Z

    We show that a system of hard discs confined to a narrow channel exhibits a fragile-strong fluid crossover located at the maximum of the isobaric heat capacity and that the relaxation times for different channel widths fall onto a single master curve when rescaled by the relaxation times and temperatures of the crossover. Calculations of the configurational entropy and the inherent structure equation of state find that the crossover is related to properties of the jamming landscape for the model but that the Adams-Gibbs relation does not predict the relaxation behavior. We also show that a facilitated dynamics description of the system, where kinetically excited regions are identified with local packing arrangements of the discs, successfully describes the fragile-strong crossover.

  3. Snow-lines as probes of turbulent diffusion in protoplanetary discs

    E-Print Network [OSTI]

    Owen, James E

    2014-01-01T23:59:59.000Z

    Sharp chemical discontinuities can occur in protoplanetary discs, particularly at `snow-lines' where a gas-phase species freezes out to form ice grains. Such sharp discontinuities will diffuse out due to the turbulence suspected to drive angular momentum transport in accretion discs. We demonstrate that the concentration gradient - in the vicinity of the snow-line - of a species present outside a snow-line but destroyed inside is strongly sensitive to the level of turbulent diffusion (provided the chemical and transport time-scales are decoupled) and provides a direct measurement of the radial `Schmidt number' (the ratio of the angular momentum transport to radial turbulent diffusion). Taking as an example the tracer species N$_2$H$^+$, which is expected to be destroyed inside the CO snow-line (as recently observed in TW Hya) we show that ALMA observations possess significant angular resolution to constrain the Schmidt number. Since different turbulent driving mechanisms predict different Schmidt numbers, a d...

  4. Gas cooling performance in disc winding of large-capacity gas-insulated transformer

    SciTech Connect (OSTI)

    Nakadate, M.; Toda, K.; Sato, K.; Biswas, D.; Nakagawa, C.; Yanari, T. [Toshiba Corp., Kawasaki (Japan)] [Toshiba Corp., Kawasaki (Japan)

    1996-04-01T23:59:59.000Z

    The authors have developed the gas-cooling system of a 275 kV, 300 MVA class gas-insulated transformer. In this study model experiments in which gas flow was substituted by water flow equivalently and 2-dimensional numerical flow analyses and network analyses were conducted. In this paper the outline of the development and optimization condition to get high cooling performance in SF{sub 6} gas-disc winding system of the transformer are presented.

  5. Free motion around black holes with discs or rings: between integrability and chaos - III

    E-Print Network [OSTI]

    P. Suková; O. Semerák

    2013-08-20T23:59:59.000Z

    We continue the study of time-like geodesic dynamics in exact static, axially and reflection symmetric space-times describing the fields of a Schwarzschild black hole surrounded by thin discs or rings. In the first paper of this series, the rise (and decline) of geodesic chaos with ring/disc mass and position and with test particle energy was revealed on Poincar\\'e sections and on time series of position or velocity and their power spectra. In the second paper we compared these results with those obtained by two recurrence methods, focusing on "sticky" orbits whose different parts show different degrees of chaoticity. Here we complement the analysis by using several Lyapunov-type coefficients which quantify the rate of orbital divergence. After comparing the results with those obtained by the previous methods, we specifically consider a system involving a black hole surrounded by a small thin disc or a large ring, having in mind the configuration which probably occurs in galactic nuclei. Within the range of parameters which roughly corresponds to our Galactic center, we found that the black-hole accretion disc does not have a significant gravitational effect on the dynamics of free motion at larger radii, while the inner circumnuclear molecular ring (concentrated above 1 parsec radius) can only induce some irregularity in motion of stars ("particles") on smaller radii if its mass reaches 10 to 30% of the central black hole (which is the upper estimate given in the literature), if it is sufficiently compact (which does not hold but maybe for its inner rim) and if the stars can get to its close vicinity. The outer dust ring between 60 and 100 parsecs appears to be less important for the geodesic dynamics in its interior.

  6. Computer simulation of Poisson's ratio of soft polydisperse discs at zero temperature

    E-Print Network [OSTI]

    Jakub Narojczyk; Krzysztof W. Wojciechowski

    2015-04-09T23:59:59.000Z

    A simple algorithm is proposed for studies of structural and elastic properties in the presence of structural disorder at zero temperature. The algorithm is used to determine the properties of the polydisperse soft disc system. It is shown that the Poisson's ratio of the system essentially depends on the size polydispersity parameter - larger polydispersity implies larger Poisson's ratio. In the presence of any size polidispersity the Poisson's ratio increases also when the interactions between the particles tend to the hard potential.

  7. The Chelyabinsk Meteor: A Cosmic Wake-up Call?

    E-Print Network [OSTI]

    Robeson, Scott M.

    The Chelyabinsk Meteor: A Cosmic Wake-up Call? Monday, Oct. 14, 8:00 PM Rawles Hall The Inaugural F, the shock wave reached the ground in Chelyabinsk Russia, breaking windows and injuring about 1500 people from flying glass. The Chelyabinsk impactor was smaller

  8. Call for Papers ACM Transactions on Modeling and Computer Simulation

    E-Print Network [OSTI]

    L'Ecuyer, Pierre

    simulation, improving the efficiency of simulations for those large systems, building effective and flexibleCall for Papers ACM Transactions on Modeling and Computer Simulation Special Issue on Simulation Pierre L'Ecuyer, University of Montreal In connection with the 2011 INFORMS Simulation Society Research

  9. India Infrastructure Report 2010 Call-for-Papers

    E-Print Network [OSTI]

    Srivastava, Kumar Vaibhav

    India Infrastructure Report 2010 Call-for-Papers We would like to invite you to contribute unpublished papers for consideration and publication in the forthcoming India Infrastructure Report (IIR) 2010, considered extremely useful by policy makers, receives wide publicity and provides an excellent forum

  10. IEEE TRANSACTIONS ON SMART GRID CALL FOR PAPERS

    E-Print Network [OSTI]

    Guan, Yongpei

    IEEE TRANSACTIONS ON SMART GRID CALL FOR PAPERS Special Issue on "Optimization Methods and Algorithms Applied to Smart Grid" With recent developments in advanced monitoring, information, and communication technologies applied to smart grid, electric power systems will be able to respond more

  11. CALL FOR PAPERS: IEEE Embedded Systems Letters Special Issue on

    E-Print Network [OSTI]

    Cheng, Albert M. K.

    manipulation of nano-structures, and space exploration. Since all these embedded systems interact directlyCALL FOR PAPERS: IEEE Embedded Systems Letters Special Issue on Rigorous Modeling and Analysis-critical monitoring and control applications. These embedded systems run real-time applications which must satisfy

  12. RADIO PROCEDURES DURING NORMAL OPERATING CONDITIONS CALLING AND COMMUNICATING TECHNIQUES

    E-Print Network [OSTI]

    Brody, James P.

    RADIO PROCEDURES DURING NORMAL OPERATING CONDITIONS CALLING AND COMMUNICATING TECHNIQUES The secret are going to say. Many people with radios have a tendency to talk and/or repeat too much. Say what you need until it is second nature. Practicing proper day-to-day radio procedures will make emergency radio

  13. Call for Nominations Women's Faculty Caucus Distinguished Mentor Award

    E-Print Network [OSTI]

    Dyer, Bill

    Call for Nominations Women's Faculty Caucus Distinguished Mentor Award The Montana State University Distinguished Mentor Award. This award is intended to recognize extraordinary efforts in mentoring women faculty faculty members. Purpose Successful mentoring is a crucial dimension of developing and retaining faculty

  14. CALL FOR PAPERS ON DYNAMICS OF HEALTH AND WELFARE

    E-Print Network [OSTI]

    Zhao, Yuxiao

    ! CALL FOR PAPERS ON DYNAMICS OF HEALTH AND WELFARE DEADLINE ­ January 2nd, 2015 Hygiea Internationalis is the official journal of the International Network for the History of Public Health efforts for the improvement of the health of populations from antiquity to modernity with particular

  15. www.mrs.org/fall2006/ CALL FOR PAPERS

    E-Print Network [OSTI]

    Akhmedov, Azer

    of recent advances in the solid-state chemistry of porous, nano-, and bulk inorganic materials methods of synthesis · Functional materials: optical, optoelectronic, polar, dielectric, ferroelectricwww.mrs.org/fall2006/ CALL FOR PAPERS MRS Symposium QQ: Solid-State Chemistry of Inorganic

  16. Calling a Spade a Spade in the MDA Infrastructure

    E-Print Network [OSTI]

    Kühne, Thomas

    Calling a Spade a Spade in the MDA Infrastructure Colin Atkinson University of Mannheim 68161 to play in the realization of the MDA. It is therefore essential that the MDA community establish a clear of metamodeling in the MDA approach is generally looked at from one angle only. The "accepted wisdom

  17. CALL FOR PAPERS The Sun Grant Initiative National Conference on

    E-Print Network [OSTI]

    Goodman, Robert M.

    on the "Science for Biomass Feedstock Production and Utilization". It will be held October 2-5, 2012 at the Hilton of best management practices for agricultural and forestry biomass feedstock production · Management CALL FOR PAPERS The Sun Grant Initiative National Conference on Science for Biomass

  18. Call for Abstracts The Bowling Green Workshop in Applied

    E-Print Network [OSTI]

    Moore, Paul A.

    Call for Abstracts The Bowling Green Workshop in Applied Ethics and Public Policy The Ethics of Self-Defense April 26-27, 2013 The Bowling Green Workshop in Applied Ethics and Public Policy will take place in Bowling Green, Ohio on April 26-27, 2013. Speakers already slated to participate include

  19. Alarm OnCall Form (Instructions) Office of Physical Security

    E-Print Network [OSTI]

    Moore, Paul A.

    Green State University Bowling Green, Ohio 43403 (419) 3727661 lockalarm@bgsu.edu This is a list; Alarm OnCall Form Office of Physical Security 101 Campus Operations Bowling Green State University Bowling Green, Ohio 43403 (419) 3727661 lockalarm@bgsu.edu Authorization of Chair

  20. Heavy Ion Collisions at the LHC - Last Call for Predictions

    E-Print Network [OSTI]

    S. Abreu; S. V. Akkelin; J. Alam; J. L. Albacete; A. Andronic; D. Antonov; F. Arleo; N. Armesto; I. C. Arsene; G. G. Barnafoldi; J. Barrette; B. Bauchle; F. Becattini; B. Betz; M. Bleicher; M. Bluhm; D. Boer; F. W. Bopp; P. Braun-Munzinger; L. Bravina; W. Busza; M. Cacciari; A. Capella; J. Casalderrey-Solana; R. Chatterjee; L. -W. Chen; J. Cleymans; B. A. Cole; Z. Conesa Del Valle; L. P. Csernai; L. Cunqueiro; A. Dainese; J. Dias de Deus H. -T. Ding; M. Djordjevic; H. Drescher; I. M. Dremin A. Dumitru; A. El; R. Engel; D. d'Enterria; K. J. Eskola; G. Fai; E. G. Ferreiro; R. J. Fries; E. Frodermann; H. Fujii; C. Gale; F. Gelis; V. P. Goncalves; V. Greco; C. Greiner; M. Gyulassy; H. van Hees; U. Heinz; H. Honkanen; W. A. Horowitz; E. Iancu; G. Ingelman; J. Jalilian-Marian; S. Jeon; A. B. Kaidalov; B. Kampfer; Z. -B. Kang; Iu. A. Karpenko; G. Kestin; D. Kharzeev; C. M. Ko; B. Koch; B. Kopeliovich; M. Kozlov; I. Kraus; I. Kuznetsova; S. H. Lee; R. Lednicky; J. Letessier; E. Levin; B. -A. Li; Z. -W. Lin; H. Liu; W. Liu; C. Loizides; I. P. Lokhtin; M. V. T. Machado; L. V. Malinina; A. M. Managadze; M. L. Mangano; M. Mannarelli; C. Manuel; G. Martinez; J. G. Milhano; A. Mocsy; D. Molnar; M. Nardi; J. K. Nayak; H. Niemi; H. Oeschler; J. -Y. Ollitrault; G. Paic; C. Pajares; V. S. Pantuev; G. Papp; D. Peressounko; P. Petreczky; S. V. Petrushanko; F. Piccinini; T. Pierog; H. J. Pirner; S. Porteboeuf; I. Potashnikova; G. Y. Qin; J. -W. Qiu; J. Rafelski; K. Rajagopal; J. Ranft; R. Rapp; S. S. Rasanen; J. Rathsman; P. Rau; K. Redlich; T. Renk; A. H. Rezaeian; D. Rischke; S. Roesler; J. Ruppert; P. V. Ruuskanen; C. A. Salgado; S. Sapeta; I. Sarcevic; S. Sarkar; L. I. Sarycheva; I. Schmidt; A. I. Shoshi; B. Sinha; Yu. M. Sinyukov; A. M. Snigirev; D. K. Srivastava; J. Stachel; A. Stasto; H. Stocker; C. Yu. Teplov; R. L. Thews; G. Torrieri; V. Topor Pop; D. N. Triantafyllopoulos; K. L. Tuchin; S. Turbide; K. Tywoniuk; A. Utermann; R. Venugopalan; I. Vitev; R. Vogt; E. Wang; X. N. Wang; K. Werner; E. Wessels; S. Wheaton; S. Wicks; U. A. Wiedemann; G. Wolschin; B. -W. Xiao; Z. Xu; S. Yasui; E. Zabrodin; K. Zapp; B. Zhang; B. -W. Zhang; H. Zhang; D. Zhou

    2007-11-06T23:59:59.000Z

    This writeup is a compilation of the predictions for the forthcoming Heavy Ion Program at the Large Hadron Collider, as presented at the CERN Theory Institute 'Heavy Ion Collisions at the LHC - Last Call for Predictions', held from May 14th to June 10th 2007.

  1. Call for Nominations 2012-2013 Chancellor's Awards for Excellence

    E-Print Network [OSTI]

    Reed, Christopher A.

    Call for Nominations 2012-2013 Chancellor's Awards for Excellence in Undergraduate Research awards for graduating seniors for outstanding research or creative activity Two awards for faculty their careers Awards are announced in the spring. Each recipient is given a crystal trophy, a certificate

  2. Call for Nominations 2013-2014 Chancellor's Awards for Excellence

    E-Print Network [OSTI]

    Reed, Christopher A.

    Call for Nominations 2013-2014 Chancellor's Awards for Excellence in Undergraduate Research awards for graduating seniors for outstanding research or creative activity Up to two awards for faculty their careers Nominations for awards may come from department chairs or other faculty; for faculty awards

  3. APRIL 1-4, 2014 | Lincoln, Neb. CALL FOR PAPERS

    E-Print Network [OSTI]

    Farritor, Shane

    in climate. Drought or the ever-present threat of it has had a pervasive effect on the region and its people/impacts in the Canadian Prairies · Ecosystem health · Agriculture and livestock impacts · The Dust Bowl and droughtDROUGHT APRIL 1-4, 2014 | Lincoln, Neb. CALL FOR PAPERS: in the Life, Cultures, and Landscapes

  4. The ejection of T Tauri stars from molecular clouds and the fate of circumstellar discs

    E-Print Network [OSTI]

    P. J. Armitage; C. J. Clarke

    1996-10-21T23:59:59.000Z

    We investigate the evolution of circumstellar discs around T Tauri stars that are ejected from small stellar clusters within molecular clouds. In particular, we study how the interaction that leads to ejection may hasten the transition between Classical and Weak-lined T Tauri status. In our models, ejections of T Tauri stars at velocities of 3-10 km/s truncate the accretion disc at radii between 1 and 10 a.u., reducing the viscous evolution time of the disc so that accretion rapidly ceases. The observational appearance of the resulting systems is then dependent on the presence or absence of a stellar magnetic field. For non-magnetic stars we find that a near-infra red excess should persist due to reprocessing of stellar radiation, but that this is greatly diminished for magnetic T Tauri stars by the presence of a magnetosphere extending to corotation. In either case, there is a period when ejected stars should appear as non-accreting systems with detectable circumstellar material at wavelengths of 5 microns and beyond. We discuss the implications of these results for models in which ejected stars contribute to the halo of pre-main-sequence objects discovered from ROSAT observations of star forming regions and the All-Sky Survey.

  5. The Gemini NICI Planet-Finding Campaign: Asymmetries in the HD 141569 disc

    E-Print Network [OSTI]

    Biller, Beth A; Rice, W Ken; Wahhaj, Zahed; Nielsen, Eric; Hayward, Thomas; Kuchner, Marc; Close, Laird M; Chun, Mark; Ftaclas, Christ; Toomey, Douglas W

    2015-01-01T23:59:59.000Z

    We report here the highest resolution near-IR imaging to date of the HD 141569A disc taken as part of the NICI Science Campaign. We recover 4 main features in the NICI images of the HD 141569 disc discovered in previous HST imaging: 1) an inner ring / spiral feature. Once deprojected, this feature does not appear circular. 2) an outer ring which is considerably brighter on the western side compared to the eastern side, but looks fairly circular in the deprojected image. 3) an additional arc-like feature between the inner and outer ring only evident on the east side. In the deprojected image, this feature appears to complete the circle of the west side inner ring and 4) an evacuated cavity from 175 AU inwards. Compared to the previous HST imaging with relatively large coronagraphic inner working angles (IWA), the NICI coronagraph allows imaging down to an IWA of 0.3". Thus, the inner edge of the inner ring/spiral feature is well resolved and we do not find any additional disc structures within 175 AU. We note ...

  6. HERO: A 3D General Relativistic Radiative Postprocessor for Accretion Discs around Black Holes

    E-Print Network [OSTI]

    Zhu, Yucong; Sadowski, Aleksander; Psaltis, Dimitrios

    2015-01-01T23:59:59.000Z

    HERO (Hybrid Evaluator for Radiative Objects) is a 3D general relativistic radiative transfer code which has been tailored to the problem of analyzing radiation from simulations of relativistic accretion discs around black holes. HERO is designed to be used as a postprocessor. Given some fixed fluid structure for the disc (i.e. density and velocity as a function of position from a hydrodynamics or magnetohydrodynamics simulation), the code obtains a self-consistent solution for the radiation field and for the gas temperatures using the condition of radiative equilibrium. The novel aspect of HERO is that it combines two techniques: 1) a short characteristics (SC) solver that quickly converges to a self consistent disc temperature and radiation field, with 2) a long characteristics (LC) solver that provides a more accurate solution for the radiation near the photosphere and in the optically thin regions. By combining these two techniques, we gain both the computational speed of SC and the high accuracy of LC. W...

  7. EM counterparts of recoiling black holes: general relativistic simulations of non-Keplerian discs

    E-Print Network [OSTI]

    Olindo Zanotti; Luciano Rezzolla; Luca Del Zanna; Carlos Palenzuela

    2010-09-12T23:59:59.000Z

    We investigate the dynamics of a circumbinary disc that responds to the loss of mass and to the recoil velocity of the black hole produced by the merger of a binary system of supermassive black holes. We perform the first two-dimensional general relativistic hydrodynamics simulations of \\textit{extended} non-Keplerian discs and employ a new technique to construct a "shock detector", thus determining the precise location of the shocks produced in the accreting disc by the recoiling black hole. In this way we can study how the properties of the system, such as the spin, mass and recoil velocity of the black hole, affect the mass accretion rate and are imprinted on the electromagnetic emission from these sources. We argue that the estimates of the bremsstrahlung luminosity computed without properly taking into account the radiation transfer yield cooling times that are unrealistically short. At the same time we show, through an approximation based on the relativistic isothermal evolution, that the luminosity produced can reach a peak value above $L \\simeq 10^{43} \\ {\\rm erg/s} $ at about $\\sim 30\\,{\\rm d}$ after the merger of a binary with total mass $M\\simeq 10^6 M_\\odot$ and persist for several days at values which are a factor of a few smaller. If confirmed by more sophisticated calculations such a signal could indeed lead to an electromagnetic counterpart of the merger of binary black-hole system.

  8. Evidence for temporal evolution in the M33 disc as traced by its star clusters

    E-Print Network [OSTI]

    Beasley, Michael A; Gallart, Carme; Sarajedini, Ata; Aparicio, Antonio

    2015-01-01T23:59:59.000Z

    We present precision radial velocities and stellar population parameters for 77 star clusters in the Local Group galaxy M33. Our GTC and WHT observations sample both young, massive clusters and known/candidate globular clusters, spanning ages ~ 10^6 - 10^10 yr, and metallicities, [M/H] ~-1.7 to solar. The cluster system exhibits an age-metallicity relation; the youngest clusters are the most metal-rich. When compared to HI data, clusters with [M/H] ~ -1.0 and younger than ~ 4 Gyr are clearly identified as a disc population. The clusters show evidence for strong time evolution in the disc radial metallicity gradient (d[M/H]dt / dR = 0.03 dex/kpc/Gyr). The oldest clusters have stronger, more negative gradients than the youngest clusters in M33. The clusters also show a clear age-velocity dispersion relation. The line of sight velocity dispersions of the clusters increases with age similar to Milky Way open clusters and stars. The general shape of the relation is reproduced by disc heating simulations, and the s...

  9. Photometric scaling relations of antitruncated stellar discs in S0-Scd galaxies

    E-Print Network [OSTI]

    Eliche-Moral, M Carmen; Beckman, John E; Gutierrez, Leonel

    2015-01-01T23:59:59.000Z

    It has been recently found that the characteristic photometric parameters of antitruncated discs in S0 galaxies follow tight scaling relations. We investigate if similar scaling relations are satisfied by galaxies of other morphological types. We have analysed the trends in several photometric planes relating the characteristic surface brightness and scalelengths of the breaks and the inner and outer discs of local antitruncated S0-Scd galaxies, using published data and fits performed to the surface brightness profiles of two samples of Type-III galaxies in the R and Spitzer 3.6 microns bands. We have performed linear fits to the correlations followed by different galaxy types in each plane, as well as several statistical tests to determine their significance. We have found that: 1) the antitruncated discs of all galaxy types from Sa to Scd obey tight scaling relations both in R and 3.6 microns, as observed in S0s; 2) the majority of these correlations are significant accounting for the numbers of the availab...

  10. IRAS 19135+3937: An SRd variable as interacting binary surrounded by a circumbinary disc

    E-Print Network [OSTI]

    Gorlova, N; Ikonnikova, N P; Burlak, M A; Komissarova, G V; Jorissen, A; Gielen, C; Debosscher, J; Degroote, P

    2015-01-01T23:59:59.000Z

    Semi-regular (SR) variables are not a homogeneous class and their variability is often explained due to pulsations and/or binarity. This study focuses on IRAS 19135+3937, an SRd variable with an infra-red excess indicative of a dusty disc. A time-series of high-resolution spectra, UBV photometry as well as a very accurate light curve obtained by the Kepler satellite, allowed us to study the object in unprecedented detail. We discovered it to be a binary with a period of 127 days. The primary has a low surface gravity and an atmosphere depleted in refractory elements. This combination of properties unambiguously places IRAS 19135+3937 in the subclass of post-Asymptotic Giant Branch stars with dusty discs. We show that the light variations in this object can not be due to pulsations, but are likely caused by the obscuration of the primary by the circumbinary disc during orbital motion. Furthermore, we argue that the double-peaked Fe emission lines provide evidence for the existence of a gaseous circumbinary Kep...

  11. A generalization of Thue's theorem to packings of non-equal discs, and an application to a discrete approximation of entropy

    E-Print Network [OSTI]

    Rom Pinchasi; Gershon Wolansky

    2014-10-13T23:59:59.000Z

    In this paper we generalize the classical theorem of Thue about the optimal circular disc packing in the plane. We are given a family of circular discs, not necessarily of equal radii, with the property that the inflation of every disc by a factor of $2$ around its center does not contain any center of another disc in the family (notice that this implies that the family of discs is a packing). We show that in this case the density of the given packing is at most $\\frac{\\pi}{2\\sqrt{3}}$, which is the density of the optimal unit disc packing. This result is used to obtain a discrete approximation to the Entropy functional in two dimensional domain.

  12. Temporal separation of two fin whale call types across the eastern North Pacific

    E-Print Network [OSTI]

    Sirovic, Ana; Williams, Lauren N; Kerosky, Sara M; Wiggins, Sean M; Hildebrand, John A

    2013-01-01T23:59:59.000Z

    The analysts visually examined 1 h LTSA windows. If therethe call type based on the LTSA, the analysts would furthern whale 40-Hz calls in an LTSA even though D calls have a

  13. Disc evolution and the relationship between $L_{\\rm acc}$ and $L_\\ast$ in T Tauri stars

    E-Print Network [OSTI]

    I. Tilling; C. J. Clarke; J. E. Pringle; C. A. Tout

    2008-01-14T23:59:59.000Z

    We investigate the evolution of accretion luminosity $L_{\\rm acc}$ and stellar luminosity ${L_\\ast}$ in pre-mainsequence stars. We make the assumption that when the star appears as a Class II object, the major phase of accretion is long past, and the accretion disc has entered its asymptotic phase. We use an approximate stellar evolution scheme for accreting pre-mainsequence stars based on Hartmann, Cassen & Kenyon, 1997. We show that the observed range of values $k = L_{\\rm acc}/L_\\ast$ between 0.01 and 1 can be reproduced if the values of the disc mass fraction $M_{\\rm disc}/M_*$ at the start of the T Tauri phase lie in the range 0.01 -- 0.2, independent of stellar mass. We also show that the observed upper bound of $L_{\\rm acc} \\sim L_\\ast$ is a generic feature of such disc accretion. We conclude that as long as the data uniformly fills the region between this upper bound and observational detection thresholds, then the degeneracies between age, mass and accretion history severely limit the use of this data for constraining possible scalings between disc properties and stellar mass.

  14. Equatorial scattering and the structure of the broad-line region in Seyfert nuclei: evidence for a rotating disc

    E-Print Network [OSTI]

    J. E. Smith; A. Robinson; S. Young; D. J. Axon; Elizabeth A. Corbett

    2005-01-28T23:59:59.000Z

    We present detailed scattering models confirming that distinctive variations in polarization across the broad Halpha line, which are observed in a significant fraction of Seyfert 1 galaxies, can be understood in terms of a rotating line-emitting disc surrounded by a co-planar scattering region (the equatorial scattering region). The predicted polarization properties are: averaged over wavelength, the position angle of polarization is aligned with the projected disc rotation axis and hence also with the radio source axis; (ii) the polarization PA rotates across the line profile, reaching equal but opposite (relative to the continuum PA) rotations in the blue and red wings; (iii) the degree of polarization peaks in the line wings and passes through a minimum in the line core. We identify 11 objects which exhibit these features to different degrees. In order to reproduce the large amplitude PA rotations observed in some cases, the scattering region must closely surround the emission disc and the latter must itself be a relatively narrow annulus -- presumably the Halpha-emitting zone of a larger accretion disc. Asymmetries in the polarization spectra may be attributable to several possible causes, including bulk radial infall in the equatorial scattering region, or contamination by polar scattered light. The broad Halpha lines do not, in general, exhibit double-peaked profiles, suggesting that a second Halpha-emitting component of the broad-line region is present, in addition to the disc.

  15. Eclipse maps of spiral shocks in the accretion disc of IP Pegasi in outburst

    E-Print Network [OSTI]

    Raymundo Baptista; E. Harlaftis; D. Steeghs

    2000-02-08T23:59:59.000Z

    Eclipse lightcurves of the dwarf nova IP Peg during the November 1996 outburst are analysed with eclipse mapping techniques to constrain the location and investigate the spatial structure of the spiral shocks observed in the Doppler tomograms (Harlaftis et al. 1999). Eclipse maps in the blue continuum and in the CIII+NIII 4650 emission line show two asymmetric arcs of \\sim 90 degrees in azimuth and extending from intermediate to the outer disc regions (R \\simeq 0.2 - 0.6 R_{L1}, where R_{L1} is the distance from disc centre to the inner Lagrangian point) which are interpreted as being the spiral shocks seen in the Doppler tomograms. The HeII 4686 eclipse map also shows two asymmetric arcs diluted by a central brightness source. The central source probably corresponds to the low-velocity component seen in the Doppler tomogram and is understood in terms of gas outflow in a wind emanating from the inner parts of the disc. We estimate that the spirals contribute about 16 and 30 per cent of the total line flux, respectively, for the HeII and CIII+NIII lines. Comparison between the Doppler and eclipse maps reveal that the Keplerian velocities derived from the radial position of the shocks are systematically larger than those inferred from the Doppler tomography indicating that the gas in the spiral shocks has sub-Keplerian velocities. We undertake simulations with the aim to investigate the effect of artifacts on the image reconstruction of the spiral structures.

  16. Better Buildings Residential Network: Lessons Learned: Peer Exchange Calls

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call:Trends2, 2013 discussThe

  17. Call issued for Lujan Neutron Scattering Center proposals

    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 3,625govInstrumentstdmadapInactiveVisiting the TWPSuccess StoriesFebruary 26,Computers »Cafeterias link toCall issued

  18. FTCP Conference Call Minutes - May 20, 2015 | Department of Energy

    Office of Environmental Management (EM)

    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 1112011 Strategic Plan| Department of.pdf6-OPAM FLASH2011-16-OPAMYoung,02,Conference Call Minutes

  19. TRIBAL ISSUES TOPIC GROUP CONFERENCE CALL SUMMARY (April 26,

    Office of Environmental Management (EM)

    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 33Frequently AskedEnergyIssues DOE'sSummaryDepartmentEnergyon MetalTO:9onWinsCONFERENCE CALL

  20. Leveraging Service Calls and Emergency Repairs for Energy Efficiency

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

    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 on Google Bookmark EERE: Alternative Fuels Data Center Home Page onYouTube YouTube Note: Since the.pdfBreaking ofOil & Gas »ofMarketing | Department of Energy Service Calls and

  1. 2013 Call for Proposals to use NERSC Resources

    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 >InternshipDepartment ofAugust 2011OctoberSeptember 201333 2013 Call for

  2. PNNL and LBNL: RCx Sensors Suitcase (CBI/ET Open Call) - 2015...

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

    PNNL and LBNL: RCx Sensors Suitcase (CBIET Open Call) - 2015 Peer Review PNNL and LBNL: RCx Sensors Suitcase (CBIET Open Call) - 2015 Peer Review Presenter: Michael Brambley and...

  3. Better Buildings Workforce Peer Exchange Call: Kick-off Call Slides and Discussion Summary. April 21, 2011

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call:Trends2,StateWorkforce Peer

  4. Migration of Earth-size planets in 3D radiative discs

    E-Print Network [OSTI]

    Lega, E; Bitsch, B; Morbidelli, A

    2014-01-01T23:59:59.000Z

    In this paper, we address the migration of small mass planets in 3D radiative disks. Indeed, migration of small planets is known to be too fast inwards in locally isothermal conditions. However, thermal effects could reverse its direction, potentially saving planets in the inner, optically thick parts of the protoplanetary disc. This effect has been seen for masses larger than 5 Earth masses, but the minimum mass for this to happen has never been probed numerically, although it is of crucial importance for planet formation scenarios. We have extended the hydro-dynamical code FARGO to 3D, with thermal diffusion. With this code, we perform simulations of embedded planets down to 2 Earth masses. For a set of discs parameters for which outward migration has been shown in the range of $[5, 35]$ Earth masses, we find that the transition to inward migration occurs for masses in the range $[3, 5]$ Earth masses. The transition appears to be due to an unexpected phenomenon: the formation of an asymmetric cold and dense...

  5. Kinetics of rapid oxidant consumption: measurements with a rotating ring disc electrode

    SciTech Connect (OSTI)

    Jaworske, D.A.

    1983-01-01T23:59:59.000Z

    Coastal and marine waters receive strong oxidants, such as ozone and chlorine, from several natural and anthropogenic sources. These oxidants react rapidly with Br/sup -/ and I/sup -/ in seawater to produce Br/sub 2/, I/sub 2/ and various hydrolysis products. The fate of these halogen products is of geochemical and biological interest. The rotating ring disc electrode (RRDE) was used to study the rapid decay of these oxidants in natural waters. Copper-plated disc experiments address the hypothesis that Cu catalyzes the decomposition of oxidant. Pseudo first-order and second-order reaction kinetics of model compounds and field samples were also studied, via in situ generation of Br/sub 3/. Pseudo first-order behavior is observed for ammonia and glycine, and the rate constants obtained from the RRDE method compare favorably with the literature (8.1 x 10/sup 7/ and 8.5 x 10/sup 7/ L/mol-sec, respectively). Second-order behavior is observed in natural water samples collected from the Patuxent River. Calculations suggest that the observed fast demand has a rate constant in excess of 10/sup 7/ L/mol-sec, and that the substrate responsible for the demand approaches concentrations of 1 x 10/sup -5/ M. The ubiquitous distribution of rapid demand, as measured in the Patuxent estuary, suggests that proteinaceous organosulfur may contribute to the observed rapid demand.

  6. Collisionless kinetic regimes for quasi-stationary axisymmetric accretion disc plasmas

    SciTech Connect (OSTI)

    Cremaschini, C. [International School for Advanced Studies (SISSA) and INFN, Trieste (Italy); Tessarotto, M. [Department of Mathematics and Geosciences, University of Trieste, Trieste (Italy)

    2012-08-15T23:59:59.000Z

    This paper is concerned with the kinetic treatment of quasi-stationary axisymmetric collisionless accretion disc plasmas. The conditions of validity of the kinetic description for non-relativistic magnetized and gravitationally bound plasmas of this type are discussed. A classification of the possible collisionless plasma regimes which can arise in these systems is proposed, which can apply to accretion discs around both stellar-mass compact objects and galactic-center black holes. Two different classifications are determined, which are referred to, respectively, as energy-based and magnetic field-based classifications. Different regimes are pointed out for each plasma species, depending both on the relative magnitudes of kinetic and potential energies and the magnitude of the magnetic field. It is shown that in all cases, there can be quasi-stationary Maxwellian-like solutions of the Vlasov equation. The perturbative approach outlined here permits unique analytical determination of the functional form for the distribution function consistent, in each kinetic regime, with the explicit inclusion of finite Larmor radius-diamagnetic and/or energy-correction effects.

  7. Free motion around black holes with discs or rings: between integrability and chaos - II

    E-Print Network [OSTI]

    O. Semerák; P. Suková

    2012-11-17T23:59:59.000Z

    We continue the study of time-like geodesic dynamics in exact static, axially and reflection symmetric space-times describing the fields of a Schwarzschild black hole surrounded by thin discs or rings. In the previous paper, the rise (and decline) of geodesic chaos with ring/disc mass and position and with test particle energy was revealed on Poincar\\'e sections, on time series of position or velocity and their power spectra, and on time evolution of the orbital `latitudinal action'. In agreement with the KAM theory of nearly integrable dynamical systems and with the results observed in similar gravitational systems in the literature, we found orbits of very different degrees of chaoticity in the phase space of perturbed fields. Here we compare selected orbits in more detail and try to classify them according to the characteristics of the corresponding phase-variable time series, mainly according to the shape of the time-series power spectra, and also applying two recurrence methods: the method of `average directional vectors', which traces the directions in which the trajectory (recurrently) passes through a chosen phase-space cell, and the `recurrence-matrix' method, which consists of statistics over the recurrences themselves. All the methods proved simple and powerful, while it is interesting to observe how they differ in sensitivity to certain types of behaviour.

  8. Lindblad resonance torques in relativistic discs: II. Computation of resonance strengths

    E-Print Network [OSTI]

    Christopher M. Hirata

    2011-03-01T23:59:59.000Z

    We present a fully relativistic computation of the torques due to Lindblad resonances from perturbers on circular, equatorial orbits on discs around Schwarzschild and Kerr black holes. The computation proceeds by establishing a relation between the Lindblad torques and the gravitational waveforms emitted by the perturber and a test particle in a slightly eccentric orbit at the radius of the Lindblad resonance. We show that our result reduces to the usual formula when taking the nonrelativistic limit. Discs around a black hole possess an m=1 inner Lindblad resonance with no Newtonian Keplerian analogue; however its strength is very weak even in the moderately relativistic regime (r/M ~ few tens), which is in part due to the partial cancellation of the two leading contributions to the resonant amplitude (the gravitoelectric octupole and gravitomagnetic quadrupole). For equatorial orbits around Kerr black holes, we find that the m=1 ILR strength is enhanced for retrograde spins and suppressed for prograde spins. We also find that the torque associated with the m>=2 inner Lindblad resonances is enhanced relative to the nonrelativistic case; the enhancement is a factor of 2 for the Schwarzschild hole even when the perturber is at a radius of 25M.

  9. Subpart W Quarterly Conference Call January 5, 2012, 11:00 am 12:00 pm

    E-Print Network [OSTI]

    , Washington, DC [DRAFT] Conference Call Notes Meeting Participants: EPA HQ: Reid Rosnick, Phil Egidi, Dan

  10. Getting Started with your LifeSize Video System Placing a Video Call

    E-Print Network [OSTI]

    Getting Started with your LifeSize Video System Placing a Video Call Dialing from the Redial list Dialing manually: Select the Video Call button. Press Enter the phone number or IP address. Press Ending a Video Call Press Select the call to terminate. Press Adjusting Sound: Press the button

  11. Anim. Behav., 1998, 55, 337350 Social calls coordinate foraging in greater spear-nosed bats

    E-Print Network [OSTI]

    Wilkinson, Gerald S.

    as they attack prey (Barclay 1982; Balcombe & Fenton 1988). Although echo- location calls can serve other

  12. Semi-flexible gas-insulated transmission line using sandwiched discs for intermittent flexing joints

    DOE Patents [OSTI]

    Kommineni, P.R.

    1983-02-15T23:59:59.000Z

    A gas-insulated transmission line includes an outer sheath, an inner conductor, an insulating gas electrically insulating the inner conductor from the outer sheath, and insulating supports insulatably supporting the inner conductor within the outer sheath. The inner conductor is provided with flexibility by the use of main conductor sections which are joined together through a conductor hub section and flexible flexing elements. Stress shields are provided to control the electric field at the locations of the conductor hub sections where the insulating supports are contacting the inner conductor. The flexing elements are formed by sandwiching together, by fusing, a pair of thin hollow discs which are fixedly secured to both the main conductor sections and the conductor hub section. 4 figs.

  13. Towards a fully consistent Milky Way disc model - III. Constraining the initial mass function

    E-Print Network [OSTI]

    Rybizki, Jan

    2015-01-01T23:59:59.000Z

    We use our vertical Milky Way disc model together with Galaxia to create mock observations of stellar samples in the solar neighbourhood. We compare these to the corresponding volume complete observational samples of dereddened and binary accounted data from Hipparcos and the Catalogue of Nearby Stars. Sampling the likelihood in the parameter space we determine a new fiducial IMF considering constraints from dwarf and giant stars. The resulting IMF observationally backed in the range from 0.5 to 10 Msun is a two slope broken power law with -1.49 +- 0.08 for the low mass slope, a break at 1.39 +- 0.05 Msun and a high mass slope of -3.02 +- 0.06. The Besancon group also converging to a similar IMF even though their observational sample being quite different to ours shows that the forward modelling technique is a powerful diagnostic to test theoretical concepts like the local field star IMF.

  14. Large-eddy simulations of isolated disc galaxies with thermal and turbulent feedback

    E-Print Network [OSTI]

    Braun, Harald; Niemeyer, Jens C; Almgren, Ann S

    2014-01-01T23:59:59.000Z

    We present a subgrid-scale model for the Multi-phase Interstellar medium, Star formation, and Turbulence (MIST) and explore its behaviour in high-resolution large-eddy simulations of isolated disc galaxies. MIST follows the evolution of a clumpy cold and a diffuse warm component of the gas within a volume element which exchange mass and energy via various cooling, heating and mixing processes. The star formation rate is dynamically computed from the state of the gas in the cold phase. An important feature of MIST is the treatment of unresolved turbulence in the two phases and its interaction with star formation and feedback by supernovae. This makes MIST a particularly suitable model for the interstellar medium in galaxy simulations. We carried out a suite of simulations varying fundamental parameters of our feedback implementation. Several observational properties of galactic star formation are reproduced in our simulations, such as an average star formation efficiency ~1%, a typical velocity dispersion arou...

  15. Biaxial nematic phase in the Maier-Saupe model for a mixture of discs and cylinders

    E-Print Network [OSTI]

    E. F. Henriques; S. R. Salinas

    2011-10-25T23:59:59.000Z

    We analyze the global phase diagram of a Maier-Saupe lattice model with the inclusion of disorder degrees of freedom to mimic a mixture of oblate and prolate molecules (discs and cylinders). In the neighborhood of a Landau multicritical point, solutions of the statistical problem can be written as a Landau-de Gennes expansion for the free energy. If the disorder degrees of freedom are quenched, we confirm the existence of a biaxial nematic strucure. If orientational and disorder degrees of freedom are allowed to thermalize, this biaxial solution becomes thermodynamically unstable. Also, we use a two-temperature formalism to mimic the presence of two distinct relaxation times, and show that a slight departure from complete thermalization is enough to stabilize a biaxial nematic phase.

  16. Lindblad Zones: resonant eccentric orbits to aid bar and spiral formation in galaxy discs

    E-Print Network [OSTI]

    Struck, Curtis

    2015-01-01T23:59:59.000Z

    The apsidal precession frequency in a fixed gravitational potential increases with the radial range of the orbit (eccentricity). Although the frequency increase is modest it can have important implications for wave dynamics in galaxy discs, which have not been previously explored in detail. One of the most interesting consequences is that for a given pattern frequency, each Lindblad resonance does not exist in isolation, but rather is the parent of a continuous sequence of resonant radii, a Lindblad Zone, with each radius in this zone characterized by a specific eccentricity. In the epicyclic approximation the precession or epicyclic frequency does not depend on epicycle size, and this phenomenon is not captured. A better approximation for eccentric orbits is provided by p-ellipse curves (Struck 2006), which do exhibit this effect. Here the p-ellipse approximation and precession-eccentricity relation are used as tools for finding the resonant radii generated from various Lindblad parent resonances. Simple, id...

  17. The effect of boundary adaptivity on hexagonal ordering and bistability in circularly confined quasi hard discs

    E-Print Network [OSTI]

    Ian Williams; Erdal C. O?uz; Robert L. Jack; Paul Bartlett; Hartmut Löwen; C. Patrick Royall

    2013-11-19T23:59:59.000Z

    The behaviour of materials under spatial confinement is sensitively dependent on the nature of the confining boundaries. In two dimensions, confinement within a hard circular boundary inhibits the hexagonal ordering observed in bulk systems at high density. Using colloidal experiments and Monte Carlo simulations, we investigate two model systems of quasi hard discs under circularly symmetric confinement. The first system employs an adaptive circular boundary, defined experimentally using holographic optical tweezers. We show that deformation of this boundary allows, and indeed is required for, hexagonal ordering in the confined system. The second system employs a circularly symmetric optical potential to confine particles without a physical boundary. We show that, in the absence of a curved wall, near perfect hexagonal ordering is possible. We propose that the degree to which hexagonal ordering is suppressed by a curved boundary is determined by the `strictness' of that wall.

  18. Cooperativity and Spatial Correlations near the Glass Transition: Computer Simulation Results for Hard Spheres and Discs

    E-Print Network [OSTI]

    Burkhard Doliwa; Andreas Heuer

    1999-12-23T23:59:59.000Z

    We examine the dynamics of hard spheres and discs at high packing fractions in two and three dimensions, modeling the simplest systems exhibiting a glass transition. As it is well known, cooperativity and dynamic heterogeneity arise as central features when approaching the glass transition from the liquid phase, so an understanding of their underlying physics is of great interest. Cooperativity implies a reduction of the effective degrees of freedom, and we demonstrate a simple way of quantification in terms of the strength and the length scale of dynamic correlations among different particles. These correlations are obtained for different dynamical quantities $X_i(t)$ that are constructed from single-particle displacements during some observation time $t$. Of particular interest is the dependence on $t$. Interestingly, for appropriately chosen $X_i(t)$ we obtain finite cooperativity in the limit $t \\to \\infty$.

  19. Semi-flexible gas-insulated transmission line using sandwiched discs for intermittent flexing joints

    DOE Patents [OSTI]

    Kommineni, Prasad R. (Westboro, MA)

    1983-02-15T23:59:59.000Z

    A gas-insulated transmission line includes an outer sheath, an inner conductor, an insulating gas electrically insulating the inner conductor from the outer sheath, and insulating supports insulatably supporting the inner conductor within the outer sheath. The inner conductor is provided with flexibility by the use of main conductor sections which are joined together through a conductor hub section and flexible flexing elements. Stress shields are provided to control the electric field at the locations of the conductor hub sections where the insulating supports are contacting the inner conductor. The flexing elements are formed by sandwiching together, by fusing, a pair of thin hollow discs which are fixedly secured to both the main conductor sections and the conductor hub section.

  20. Self-similar Evolution of Self-Gravitating Viscous Accretion Discs

    E-Print Network [OSTI]

    Illenseer, Tobias F

    2015-01-01T23:59:59.000Z

    A new one-dimensional, dynamical model is proposed for geometrically thin, self-gravitating viscous accretion discs. The vertically integrated equations are simplified using the slow accretion limit and the monopole approximation with a time-dependent central point mass to account for self-gravity and accretion. It is shown that the system of partial differential equations can be reduced to a single non-linear advection diffusion equation which describes the time evolution of angular velocity. In order to solve the equation three different turbulent viscosity prescriptions are considered. It is shown that for these parametrizations the differential equation allows for similarity transformations depending only on a single non-dimensional parameter. A detailed analysis of the similarity solutions reveals that this parameter is the initial power law exponent of the angular velocity distribution at large radii. The radial dependence of the self-similar solutions is in most cases given by broken power laws. At sma...

  1. Free motion around black holes with discs or rings: between integrability and chaos -- IV

    E-Print Network [OSTI]

    V. Witzany; O. Semerak; P. Sukova

    2015-03-31T23:59:59.000Z

    The dynamical system studied in previous papers of this series, namely a bound time-like geodesic motion in the exact static and axially symmetric space-time of an (originally) Schwarzschild black hole surrounded by a thin disc or ring, is considered to test whether the often employed "pseudo-Newtonian" approach (resorting to Newtonian dynamics in gravitational potentials modified to mimic the black-hole field) can reproduce phase-space properties observed in the relativistic treatment. By plotting Poincar\\'e surfaces of section and using two recurrence methods for similar situations as in the relativistic case, we find similar tendencies in the evolution of the phase portrait with parameters (mainly with mass of the disc/ring and with energy of the orbiters), namely those characteristic to weakly non-integrable systems. More specifically, this is true for the Paczy\\'nski--Wiita and a newly suggested logarithmic potential, whereas the Nowak--Wagoner potential leads to a different picture. The potentials and the exact relativistic system clearly differ in delimitation of the phase-space domain accessible to a given set of particles, though this mainly affects the chaotic sea whereas not so much the occurrence and succession of discrete dynamical features (resonances). In the pseudo-Newtonian systems, the particular dynamical features generally occur for slightly smaller values of the perturbation parameters than in the relativistic system, so one may say that the pseudo-Newtonian systems are slightly more prone to instability. We also add remarks on numerics (a different code is used than in previous papers), on the resemblance of dependence of the dynamics on perturbing mass and on orbital energy, on the difference between the Newtonian and relativistic Bach--Weyl rings, and on the relation between Poincar\\'e sections and orbital shapes within the meridional plane.

  2. Heavy Ion Collisions at the LHC - Last Call for Predictions

    SciTech Connect (OSTI)

    Armesto, N; Borghini, N; Jeon, S; Wiedemann, U A; Abreu, S; Akkelin, V; Alam, J; Albacete, J L; Andronic, A; Antonuv, D; Arleo, F; Armesto, N; Arsene, I C; Barnafoldi, G G; Barrette, J; Bauchle, B; Becattini, F; Betz, B; Bleicher, M; Bluhm, M; Boer, D; Bopp, F W; Braun-Munzinger, P; Bravina, L; Busza, W; Cacciari, M; Capella, A; Casalderrey-Solana, J; Chatterjee, R; Chen, L; Cleymans, J; Cole, B A; delValle, Z C; Csernai, L P; Cunqueiro, L; Dainese, A; de Deus, J D; Ding, H; Djordjevic, M; Drescher, H; Dremin, I M; Dumitru, A; El, A; Engel, R; d'Enterria, D; Eskola, K J; Fai, G; Ferreiro, E G; Fries, R J; Frodermann, E; Fujii, H; Gale, C; Gelis, F; Goncalves, V P; Greco, V; Gyulassy, M; van Hees, H; Heinz, U; Honkanen, H; Horowitz, W A; Iancu, E; Ingelman, G; Jalilian-Marian, J; Jeon, S; Kaidalov, A B; Kampfer, B; Kang, Z; Karpenko, I A; Kestin, G; Kharzeev, D; Ko, C M; Koch, B; Kopeliovich, B; Kozlov, M; Kraus, I; Kuznetsova, I; Lee, S H; Lednicky, R; Letessier, J; Levin, E; Li, B; Lin, Z; Liu, H; Liu, W; Loizides, C; Lokhtin, I P; Machado, M T; Malinina, L V; Managadze, A M; Mangano, M L; Mannarelli, M; Manuel, C; Martinez, G; Milhano, J G; Mocsy, A; Molnar, D; Nardi, M; Nayak, J K; Niemi, H; Oeschler, H; Ollitrault, J; Paic, G; Pajares, C; Pantuev, V S; Papp, G; Peressounko, D; Petreczky, P; Petrushanko, S V; Piccinini, F; Pierog, T; Pirner, H J; Porteboeuf, S; Potashnikova, I; Qin, G Y; Qiu, J; Rafelski, J; Rajagopal, K; Ranft, J; Rapp, R; Rasanen, S S; Rathsman, J; Rau, P; Redlich, K; Renk, T; Rezaeian, A H; Rischke, D; Roesler, S; Ruppert, J; Ruuskanen, P V; Salgado, C A; Sapeta, S; Sarcevic, I; Sarkar, S; Sarycheva, L I; Schmidt, I; Shoski, A I; Sinha, B; Sinyukov, Y M; Snigirev, A M; Srivastava, D K; Stachel, J; Stasto, A; Stocker, H; Teplov, C Y; Thews, R L; Torrieri, G; Pop, V T; Triantafyllopoulos, D N; Tuchin, K L; Turbide, S; Tywoniuk, K; Utermann, A; Venugopalan, R; Vitev, I; Vogt, R; Wang, E; Wang, X N; Werner, K; Wessels, E; Wheaton, S; Wicks, S; Wiedemann, U A; Wolschin, G; Xiao, B; Xu, Z; Yasui, S; Zabrodin, E; Zapp, K; Zhang, B

    2008-02-25T23:59:59.000Z

    In August 2006, the CERN Theory Unit announced to restructure its visitor program and to create a 'CERN Theory Institute', where 1-3 month long specific programs can take place. The first such Institute was held from 14 May to 10 June 2007, focusing on 'Heavy Ion Collisions at the LHC - Last Call for Predictions'. It brought together close to 100 scientists working on the theory of ultra-relativistic heavy ion collisions. The aim of this workshop was to review and document the status of expectations and predictions for the heavy ion program at the Large Hadron Collider LHC before its start. LHC will explore heavy ion collisions at {approx} 30 times higher center of mass energy than explored previously at the Relativistic Heavy Ion Collider RHIC. So, on the one hand, the charge of this workshop provided a natural forum for the exchange of the most recent ideas, and allowed to monitor how the understanding of heavy ion collisions has evolved in recent years with the data from RHIC, and with the preparation of the LHC experimental program. On the other hand, the workshop aimed at a documentation which helps to distinguish pre- from post-dictions. An analogous documentation of the 'Last Call for Predictions' [1] was prepared prior to the start of the heavy-ion program at the Relativistic Heavy Ion Collider RHIC, and it proved useful in the subsequent discussion and interpretation of RHIC data. The present write-up is the documentation of predictions for the LHC heavy ion program, received or presented during the CERN TH Institute. The set-up of the CERN TH Institute allowed us to aim for the wide-most coverage of predictions. There were more than 100 presentations and discussions during the workshop. Moreover, those unable to attend could still participate by submitting predictions in written form during the workshop. This followed the spirit that everybody interested in making a prediction had the right to be heard. To arrive at a concise document, we required that each prediction should be summarized on at most two pages, and that predictions should be presented, whenever possible, in figures which display measurable quantities. Full model descriptions were not accepted--the authors were encouraged to indicate the relevant references for the interested reader. Participants had the possibility to submit multiple contributions on different topics, but it was part of the subsequent editing process to ensure that predictions on neighboring topics were merged wherever possible. The contributions summarized here are organized in several sections,--though some of them contain material related with more than one section--roughly by going from low transverse momentum to high transverse momentum and from abundant to rare measurements. In the low transverse momentum regime, we start with predictions on multiplicity distributions, azimuthal asymmetries in particle production and hadronic flavor observables, followed by correlation and fluctuation measurements. The contributions on hard probes at the LHC start with predictions for single inclusive high transverse momentum spectra, and jets, followed by heavy quark and quarkonium measurements, leptonic probes and photons. A final section 'Others' encompasses those predictions which do not fall naturally within one of the above-mentioned categories, or discuss the more speculative phenomena that may be explored at the LHC.

  3. Flow tests of the Gladys McCall well

    SciTech Connect (OSTI)

    Randolph, P.L.; Hayden, C.G.; Rogers, L.A. (Institute of Gas Technology, Chicago, IL (United States))

    1992-04-01T23:59:59.000Z

    This report pulls together the data from all of the geopressured-geothermal field research conducted at the Gladys McCall well. The well produced geopressured brine containing dissolved natural gas from the Lower Miocene sands at a depth of 15,150 to 16,650 feet. More than 25 million barrels of brine and 727 million standard cubic feet of natural gas were produced in a series of flow tests between December 1982 and October 1987 at various brine flow rates up to 28,000 barrels per day. Initial short-term flow tests for the Number 9 Sand found the permeability to be 67 to 85 md (millidarcies) for a brine volume of 85 to 170 million barrels. Initial short-term flow tests for the Number 8 Sand found a permeability of 113 to 132 md for a reservoir volume of 430 to 550 million barrels of brine. The long-term flow and buildup test of the Number 8 Sand found that the high-permeability reservoir connected to the wellbore (measured by the short-term flow test) was connected to a much larger, low-permeability reservoir. Numerical simulation of the flow and buildup tests required this large connected reservoir to have a volume of about 8 billion barrels (two cubic miles of reservoir rock) with effective permeabilities in the range of 0.2 to 20 md. Calcium carbonate scale formation in the well tubing and separator equipment was a problem. During the first 2 years of production, scale formation was prevented in the surface equipment by injection of an inhibitor upstream of the choke. Starting in 1985, scale formation in the production tubing was successfully prevented by injecting inhibitor pills'' directly into the reservoir. Corrosion and/or erosion of surface piping and equipment, as well as disposal well tubing, was also significant.

  4. 2015 Call for Proposals for the Department of Energy (DOE) Nuclear...

    Energy Savers [EERE]

    5 Call for Proposals for the Department of Energy (DOE) Nuclear Safety Research and Development (NSR&D) Program 2015 Call for Proposals for the Department of Energy (DOE) Nuclear...

  5. What Those Call Numbers Mean: The Library of Congress Classification System

    E-Print Network [OSTI]

    Hutcheon, James M.

    What Those Call Numbers Mean: The Library of Congress Classification System The call number system that we use in this library, which is called the Library of Congress Classification System subject areas. If you know what letter indicates the classification for the subject you need, you can find

  6. Effect of autologous platelet-rich plasma-releasate on intervertebral disc degeneration in the rabbit anular puncture model: a preclinical study

    E-Print Network [OSTI]

    2012-01-01T23:59:59.000Z

    discs. Autologous PRP and PPP (platelet-poor plasma) werethe initial puncture, releasate isolated from clotted PPP orPRP (PPP- or PRP-releasate), or phosphate-buffered saline (

  7. Standing spin-wave mode structure and linewidth in partially disordered hexagonal arrays of perpendicularly magnetized sub-micron Permalloy discs

    SciTech Connect (OSTI)

    Ross, N., E-mail: rossn2282@gmail.com; Kostylev, M., E-mail: mikhail.kostylev@uwa.edu.au [School of Physics, University of Western Australia, Crawley, WA (Australia); Stamps, R. L. [School of Physics, University of Western Australia, Crawley, WA (Australia); SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom)

    2014-09-21T23:59:59.000Z

    Standing spin wave mode frequencies and linewidths in partially disordered perpendicular magnetized arrays of sub-micron Permalloy discs are measured using broadband ferromagnetic resonance and compared to analytical results from a single, isolated disc. The measured mode structure qualitatively reproduces the structure expected from the theory. Fitted demagnetizing parameters decrease with increasing array disorder. The frequency difference between the first and second radial modes is found to be higher in the measured array systems than predicted by theory for an isolated disc. The relative frequencies between successive spin wave modes are unaffected by reduction of the long-range ordering of discs in the array. An increase in standing spin wave resonance linewidth at low applied magnetic fields is observed and grows more severe with increased array disorder.

  8. Intra- and interspecific responses to Rafinesque’s big-eared bat (Corynorhinus rafinesquii) social calls.

    SciTech Connect (OSTI)

    Loeb, Susan, C.; Britzke, Eric, R.

    2010-07-01T23:59:59.000Z

    Bats respond to the calls of conspecifics as well as to calls of other species; however, few studies have attempted to quantify these responses or understand the functions of these calls. We tested the response of Rafinesque’s big-eared bats (Corynorhinus rafinesquii) to social calls as a possible method to increase capture success and to understand the function of social calls. We also tested if calls of bats within the range of the previously designated subspecies differed, if the responses of Rafinesque’s big-eared bats varied with geographic origin of the calls, and if other species responded to the calls of C. rafinesquii. We recorded calls of Rafinesque’s big-eared bats at two colony roost sites in South Carolina, USA. Calls were recorded while bats were in the roosts and as they exited. Playback sequences for each site were created by copying typical pulses into the playback file. Two mist nets were placed approximately 50–500 m from known roost sites; the net with the playback equipment served as the Experimental net and the one without the equipment served as the Control net. Call structures differed significantly between the Mountain and Coastal Plains populations with calls from the Mountains being of higher frequency and longer duration. Ten of 11 Rafinesque’s big-eared bats were caught in the Control nets and, 13 of 19 bats of other species were captured at Experimental nets even though overall bat activity did not differ significantly between Control and Experimental nets. Our results suggest that Rafinesque’s big-eared bats are not attracted to conspecifics’ calls and that these calls may act as an intraspecific spacing mechanism during foraging.

  9. Dust Settling in Magnetorotationally-Driven Turbulent Discs I: Numerical Methods and Evidence for a Vigorous Streaming Instability

    E-Print Network [OSTI]

    Dinshaw S. Balsara; David A. Tilley; Terrence Rettig; Sean A. Brittain

    2008-10-01T23:59:59.000Z

    (Abridged) In this paper we have used the RIEMANN code for computational astrophysics to study the interaction of a realistic distribution of dust grains with gas in a vertically stratified protostellar accretion disc. The disc was modeled to have the density and temperature of a minimum mass solar nebula, and was driven to a fully-developed turbulence via the magnetorotational instability (MRI). We find that the inclusion of standard dust to gas ratios does not have any significant effect on the MRI even when the dust sediments to the midplane of the accretion disc. The density distribution of the dust reaches a Gaussian profile, and the scale heights for the dust that we derive are shown to be proportional to the reciprocal of the square root of the dust radius. The largest dust shows a strong tendency to settle to the midplane of the accretion disc, and tends to organize itself into elongated clumps of high density. The dynamics of these clumps is shown to be consistent with a streaming instability. The streaming instability is seen to be very vigorous and persistent once it forms. Each stream of high density dust displays a reduced RMS velocity dispersion, and the densest clumpings of large dust are shown to form where the streams intersect. We have also shown that the mean free path and collision time for the dust that participates in the streaming instability is reduced by almost two orders of magnitude relative to the average mean free paths and collision times. We show that some of the large dust in our 10 au simulations should have a propensity for grain coalescence.

  10. X-ray and Multiwavelength Insights into the Inner Structure of High-Luminosity Disc-Like Emitters

    E-Print Network [OSTI]

    Luo, B; Eracleous, M; Wu, Jian; Hall, P B; Rafiee, A; Schneider, D P; Wu, Jianfeng

    2012-01-01T23:59:59.000Z

    We present X-ray and multiwavelength studies of a sample of eight high-luminosity active galactic nuclei (AGNs) with disc-like H\\beta emission-line profiles selected from the Sloan Digital Sky Survey Data Release 7. These sources have higher redshift (z~0.6) than the majority of the known disc-like emitters, and they occupy a largely unexplored space in the luminosity-redshift plane. Seven sources have typical AGN X-ray spectra with power-law photon indices of \\Gamma~1.4-2.0; two of them show some X-ray absorption (column density N_H~10^{21}-10^{22} cm^{-2}$ for neutral gas). The other source, J0850+4451, has only three hard X-ray photons detected and is probably heavily obscured (N_H>3x10^{23} cm^{-2}). This object is also identified as a low-ionization broad absorption line (BAL) quasar based on Mg II \\lambda2799 absorption; it is the first disc-like emitter reported that is also a BAL quasar. The IR-to-UV spectral energy distributions (SEDs) of these eight sources are similar to the mean SEDs of typical qu...

  11. The number fraction of discs around brown dwarfs in Orion OB1a and the 25 Orionis group

    E-Print Network [OSTI]

    Downes, Juan José; Ballesteros-Paredes, Javier; Mateu, Cecilia; Briceño, César; Hernández, Jesús; Petr-Gotzens, Monika G; Calvet, Nuria; Hartmann, Lee; Mauco, Karina

    2015-01-01T23:59:59.000Z

    We present a study of 15 new brown dwarfs belonging to the $\\sim7$ Myr old 25 Orionis group and Orion OB1a sub-association with spectral types between M6 and M9 and estimated masses between $\\sim0.07$M$_\\odot$ and $\\sim0.01$ M$_\\odot$. By comparing them through a Bayesian method with low mass stars ($0.8\\lesssim$ M/M$_\\odot\\lesssim0.1$) from previous works in the 25 Orionis group, we found statistically significant differences in the number fraction of classical T Tauri stars, weak T Tauri stars, class II, evolved discs and purely photospheric emitters at both sides of the sub-stellar mass limit. Particularly we found a fraction of $3.9^{+2.4}_{-1.6}~\\%$ low mass stars classified as CTTS and class II or evolved discs, against a fraction of $33.3^{+10.8}_{-9.8}~\\%$ in the sub-stellar mass domain. Our results support the suggested scenario in which the dissipation of discs is less efficient for decreasing mass of the central object.

  12. Solar Space Density of the Red Clump Stars and the Scale-length of the Thin Disc

    E-Print Network [OSTI]

    Gokce, E Yaz; Duran, S; Bilir, S; Yalcinkaya, A; Ak, S; Ak, T; Lopez-Corredoira, M; Cabrera-Lavers, A

    2015-01-01T23:59:59.000Z

    We estimated the scale-length of the thin disc with the J and W1 magnitudes of the most probable Red Clump (RC) stars in the Galactic plane, $-0\\overset{^\\circ}.5 \\leq b \\leq +0\\overset{^\\circ}.5$, in 19 equal sized fields with consecutive Galactic longitudes which cover the interval $90^\\circ \\leq l \\leq 270^\\circ$. Our results are constrained with respect to the solar space density ($D^*=5.95$), which indicates that the radial variation of the density is lower for higher Galactocentric distances. The scale-length of the thin disc is 2 kpc for the fields in the Galactic anticentre direction or close to this direction, while it decreases continuously in the second and third quadrants reaching to a lower limit of $h$ = 1.6 kpc at the Galactic longitudes $l$ = 90$^\\circ$ and $l$ = 270$^\\circ$. The distribution of the scale-length in 19 fields is consistent with the predictions from the Galaxia model and its variation with longitude is probably due to the inhomogeneity structure of the disc caused by the accrete...

  13. Effects of Ohmic and ambipolar diffusion on the formation and evolution of the first core, protostar and circumstellar disc

    E-Print Network [OSTI]

    Tsukamoto, Yusuke; Okuzumi, Satoshi; Machida, Masahiro N; Inutsuka, Shu-ichiro

    2015-01-01T23:59:59.000Z

    We investigate the formation and evolution of the first core, protostar, and circumstellar disc with a three-dimensional non-ideal (including both Ohmic and ambipolar diffusion) radiation magnetohydrodynamics simulation. We found that the magnetic flux is largely removed by magnetic diffusion in the first core phase and that the plasma $\\beta$ of the centre of the first core becomes large, $\\beta>10^4$. On the other hand, in an ideal simulation, $\\beta\\sim 10$ at the centre of the first core. Even though $\\beta$ inside the first core thus differs significantly between the resistive and ideal model, the angular momentum of the first core does not. The simulations with magnetic diffusion show that the circumstellar disc forms at almost the same time of protostar formation even with a relatively strong initial magnetic field (the value for the initial mass-to-flux ratio of the cloud core relative to the critical value is $\\mu=4$). The disc has a radius of $r \\sim 1$ AU at the protostar formation epoch. We confir...

  14. On the mechanism of self gravitating Rossby interfacial waves in proto-stellar accretion discs

    E-Print Network [OSTI]

    Yellin-Bergovoy, Ron; Umurhan, Orkan M

    2015-01-01T23:59:59.000Z

    The dynamical response of edge waves under the influence of self-gravity is examined in an idealized two-dimensional model of a proto-stellar disc, characterized in steady state as a rotating vertically infinite cylinder of fluid with constant density except for a single density interface at some radius r0. The fluid in basic state is prescribed to rotate with a Keplerian profile $\\Omega_k(r)\\sim r^{-3/2}$ modified by some additional azimuthal sheared flow. A linear analysis shows that there are two azimuthally propagating edge waves, kin to the familiar Rossby waves and surface gravity waves in terrestrial studies, which move opposite to one another with respect to the local basic state rotation rate at the interface. Instability only occurs if the radial pressure gradient is opposite to that of the density jump (unstably stratified) where self-gravity acts as a wave stabilizer irrespective of the stratification of the system. The propagation properties of the waves are discussed in detail in the language of...

  15. Review of Multi-Person Exposure Calls to a Regional Poison Control Center

    E-Print Network [OSTI]

    Morgan, Brent W; Skinner, Carl G; Kleiman, Richard J; Geller, Robert J; Chang, Arthur S

    2010-01-01T23:59:59.000Z

    Exposure Calls to a Regional Poison Control Center Brent W.Medicine and the Georgia Poison Center, Atlanta, GA †of Pediatrics and the Georgia Poison Center, Atlanta, GA

  16. NREL - FY09 Lab Call: Supporting Research and Testing for MHK...

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

    and Hydrokinetic Technologies FY 09 Lab Call: Research & Assessment for MHK Development Effects on the Physical Environment (Hydrodynamics, Sediment Transport, and Water Quality...

  17. Behavioral context of call production by eastern North Pacific blue whales

    E-Print Network [OSTI]

    Oleson, Erin M; Calambokidis, J; Burgess, W C; McDonald, M A; LeDuc, C A; Hildebrand, J A

    2007-01-01T23:59:59.000Z

    by eastern North Pacific blue whales Erin M. Oleson 1, *,context of calls produced by blue whales Balaenoptera mus-North Pacific population of blue whales (Thompson 1965,

  18. U.S. Department of Energy Earth Day 2015 Photo Contest CALLING...

    Office of Environmental Management (EM)

    Earth Day 2015 Photo Contest CALLING ALL PHOTOGRAPHERS Professionals, amateurs, and the camera sharp shooter We invite all DOE employees and DOE contractors to share images of...

  19. Energy Regulation, Roll Call Votes and Regional Resources: Evidence from Russia

    E-Print Network [OSTI]

    Grigoriadis, Theocharis N; Torgler, Benno

    2007-01-01T23:59:59.000Z

    Problems of the North 20. Regulation and Work organizationV. "Reform and Regulation of Natural Monopolies." (InEnergy Regulation, Roll Call Votes and Regional Resources:

  20. 2:30 PM TODAY: On-the-Record Conference Call with Deputy Assistant...

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

    Gov. Granholm, Administration Officials to Preview the President's Trip to Holland, Michigan 4:45PM ET TODAY: On-the-Record Conference Call with Administration, Jobs Council...

  1. THE 12th METU CONFERENCE ON INTERNATIONAL RELATIONS -CALL FOR PAPERS Turkey in the World

    E-Print Network [OSTI]

    Hasýrcý, Vasýf

    THE 12th METU CONFERENCE ON INTERNATIONAL RELATIONS - CALL FOR PAPERS Turkey in the World - CALL in Turkey on international relations, is going to be held between 12-14 June 2013, marking its 12th year in approximately 50 panels and roundtables. The topic of this year's conference is Turkey in the World. In recent

  2. Put-Call Parity (Castelli, 1877) C = P + S -PV(X). (19)

    E-Print Network [OSTI]

    Lyuu, Yuh-Dauh

    Put-Call Parity (Castelli, 1877) C = P + S - PV(X). (19) · Consider the portfolio of one short European call, one long European put, one share of stock, and a loan of PV(X). · All options are assumed - S + PV(X). c 2010 Prof. Yuh-Dauh Lyuu, National Taiwan University Page 185 #12;The Proof (continued

  3. Call For Paper: The Electronic Library Special Issue on Multilinguality in Digital Libraries

    E-Print Network [OSTI]

    He, Daqing

    Call For Paper: The Electronic Library Special Issue on Multilinguality in Digital Libraries, and universal access library services using collections of digital information and delivering over an information infrastructure at the global scale. This so called digital library brings together researchers

  4. Ethical Corporation: By Invitation -Climate change: Calling the fossil fuel abolitionists EC Newsdesk

    E-Print Network [OSTI]

    Hoffman, Andrew J.

    in a fossil fuel-based economy. Fossil fuels are our primary source of energy and support our entire wayEthical Corporation: By Invitation - Climate change: Calling the fossil fuel abolitionists EC Newsdesk 28 May 08 Where is the green Wilberforce? By Invitation: Climate change: Calling the fossil fuel

  5. Space-Profiling Semantics of the Call-by-Value Lambda Calculus and the CPS Transformation

    E-Print Network [OSTI]

    Minamide, Yasuhiko

    Space-Profiling Semantics of the Call-by-Value Lambda Calculus and the CPS Transformation Yasuhiko preserves space required for execution of a program within a constant factor. For the call-by-value lambda calculus we adopt a space-profiling semantics based on the profiling semantics of NESL by Blelloch

  6. Better Buildings Residential Network Workforce/Business Partners Peer Exchange Call Series: Trends in Contractor Conversion Rates Call Slides and Discussion Summary, December 5, 2013

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call:Trends inWorkforceCall

  7. Past Calls

    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 for4,645U.S. DOE Office of Science (SC)IntegratedSpeeding access toTestPhysicsParticipantsPartners of the MFRCOmbudsProposals

  8. Light-induced disassembly of dusty bodies in inner protoplanetary discs: implications for the formation of planets

    E-Print Network [OSTI]

    Gerhard Wurm

    2007-09-09T23:59:59.000Z

    Laboratory experiments show that a solid-state greenhouse effect in combination with thermophoresis can efficiently erode a dust bed in a low-pressure gaseous environment. The surface of an illuminated, light absorbing dusty body is cooler than the dust below the surface (solidstate greenhouse effect). This temperature gradient leads to a directed momentum transfer between gas and dust particles and the dust particles are subject to a force towards the surface(thermophoresis). If the thermophoretic force is stronger than gravity and cohesion, dust particles are ejected. Applied to protoplanetary discs, dusty bodies smaller than several kilometres in size which are closer to a star than about 0.4 au are subject to a rapid and complete disassembly to submillimetre size dust aggregates by this process. While an inward-drifting dusty body is destroyed, the generated dust is not lost for the disc by sublimation or subsequent accretion on to the star but can be reprocessed by photophoresis or radiation pressure. Planetesimals cannot originate through aggregation of dust inside the erosion zone. If objects larger than several kilometres already exist, they prevail and further grow by collecting dust from disassembled smaller bodies. The pile-up of solids in a confined inner region of the disc, in general, boosts the formation of planets. Erosion is possible in even strongly gas-depleted inner regions as observed for TW Hya. Reprocessing of dust through light-induced erosion offers one possible explanation for growth of large cores of gas-poor giant planets in a gas-starved region as recently found around HD 149026b.

  9. 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.

  10. EU, Japan call for dialogue amid row on breakthrough nuclear project The European Union and Japan each called Wednesday for dialogue among the six partners on

    E-Print Network [OSTI]

    if Japan did not host ITER. Japan has also said it is ready to discuss compromises. Nuclear Power Plant Discount new & used items. affil Search for nuclear power plant now! American Nuclear Society Nuclear Power Plant Wall Maps published by Nuclear News Ads by Goooooogle 12/1/04 10:30 AMEUbusiness - EU, Japan call

  11. Call Me! Calling the Glacier

    E-Print Network [OSTI]

    Laar, Kalle

    2009-01-01T23:59:59.000Z

    power, one additional solar panel has been installed feedingpower was supplied by solar panels, feeding an accumulatorhappen, and once the solar panels see the sun, the station

  12. Call Me! Calling the Glacier

    E-Print Network [OSTI]

    Laar, Kalle

    2009-01-01T23:59:59.000Z

    was installed for the ars electronica Linz 2007. Ever sinceinvitation of the ars electronica Linz 2007 with the help of

  13. Light-induced disassembly of dusty bodies in inner protoplanetary discs: implications for the formation of planets

    E-Print Network [OSTI]

    Wurm, Gerhard

    2007-01-01T23:59:59.000Z

    Laboratory experiments show that a solid-state greenhouse effect in combination with thermophoresis can efficiently erode a dust bed in a low-pressure gaseous environment. The surface of an illuminated, light absorbing dusty body is cooler than the dust below the surface (solidstate greenhouse effect). This temperature gradient leads to a directed momentum transfer between gas and dust particles and the dust particles are subject to a force towards the surface(thermophoresis). If the thermophoretic force is stronger than gravity and cohesion, dust particles are ejected. Applied to protoplanetary discs, dusty bodies smaller than several kilometres in size which are closer to a star than about 0.4 au are subject to a rapid and complete disassembly to submillimetre size dust aggregates by this process. While an inward-drifting dusty body is destroyed, the generated dust is not lost for the disc by sublimation or subsequent accretion on to the star but can be reprocessed by photophoresis or radiation pressure. Pl...

  14. The morphology of the Milky Way - II. Reconstructing CO maps from disc galaxies with live stellar distributions

    E-Print Network [OSTI]

    Pettitt, Alex R; Acreman, David M; Bate, Matthew R

    2015-01-01T23:59:59.000Z

    The arm structure of the Milky Way remains somewhat of an unknown, with observational studies hindered by our location within the Galactic disc. In the work presented here we use smoothed particle hydrodynamics (SPH) and radiative transfer to create synthetic longitude-velocity observations. Our aim is to reverse-engineer a top down map of the Galaxy by comparing synthetic longitude-velocity maps to those observed. We set up a system of N-body particles to represent the disc and bulge, allowing for dynamic creation of spiral features. Interstellar gas, and the molecular content, is evolved alongside the stellar system. A 3D-radiative transfer code is then used to compare the models to observational data. The resulting models display arm features that are a good reproduction of many of the observed emission structures of the Milky Way. These arms however are dynamic and transient, allowing for a wide range of morphologies not possible with standard density wave theory. The best fitting models are a much better...

  15. The vertical effects of disc non-axisymmetries from perturbation theory: the case of the Galactic bar

    E-Print Network [OSTI]

    Monari, Giacomo; Siebert, Arnaud

    2015-01-01T23:59:59.000Z

    Evidence for non-zero mean stellar velocities in the direction perpendicular to the Galactic plane has been accumulating from various recent large spectroscopic surveys. Previous analytical and numerical work has shown that a "breathing mode" of the Galactic disc, similar to what is observed in the Solar vicinity, can be the natural consequence of a non-axisymmetric internal perturbation of the disc. Here we provide a general analytical framework, in the context of perturbation theory, allowing us to compute the vertical bulk motions generated by a single internal perturber (bar or spiral pattern). In the case of the Galactic bar, we show that these analytically predicted bulk motions are well in line with the outcome of a numerical simulation. The mean vertical motions induced by the Milky Way bar are small (mean velocity of less than 1 km/sec) and cannot be responsible alone for the observed breathing mode, but they are existing. Our analytical treatment is valid close to the plane for all the non-axisymmet...

  16. Percutaneous Transcatheter One-Step Mechanical Aortic Disc Valve Prosthesis Implantation: A Preliminary Feasibility Study in Swine

    SciTech Connect (OSTI)

    Sochman, Jan [Institute for Clinical and Experimental Medicine, Intensive Care Unit, Clinic of Cardiology (Czech Republic)], E-mail: jan.sochman@medicon.cz; Peregrin, Jan H.; Rocek, Miloslav [Institute for Clinical and Experimental Medicine, Department of Diagnostic and Interventional Radiology (Czech Republic); Timmermans, Hans A.; Pavcnik, Dusan; Roesch, Josef [Oregon Health and Sciences University, Dotter Interventional Institute (United States)

    2006-02-15T23:59:59.000Z

    Purpose. To evaluate the feasibility of one-step implantation of a new type of stent-based mechanical aortic disc valve prosthesis (MADVP) above and across the native aortic valve and its short-term function in swine with both functional and dysfunctional native valves. Methods. The MADVP consisted of a folding disc valve made of silicone elastomer attached to either a nitinol Z-stent (Z model) or a nitinol cross-braided stent (SX model). Implantation of 10 MADVPs (6 Z and 4 SX models) was attempted in 10 swine: 4 (2 Z and 2 SX models) with a functional native valve and 6 (4 Z and 2 SX models) with aortic regurgitation induced either by intentional valve injury or by MADVP placement across the native valve. MADVP function was observed for up to 3 hr after implantation. Results. MADVP implantation was successful in 9 swine. One animal died of induced massive regurgitation prior to implantation. Four MADVPs implanted above functioning native valves exhibited good function. In 5 swine with regurgitation, MADVP implantation corrected the induced native valve dysfunction and the device's continuous good function was observed in 4 animals. One MADVP (SX model) placed across native valve gradually migrated into the left ventricle. Conclusion. The tested MADVP can be implanted above and across the native valve in a one-step procedure and can replace the function of the regurgitating native valve. Further technical development and testing are warranted, preferably with a manufactured MADVP.

  17. Call for Papers "Distributed Cloud Computing" Program Chairs Yvonne Coady, Uni Victoria, Canada,

    E-Print Network [OSTI]

    Schmid, Stefan

    Call for Papers "Distributed Cloud Computing" Program Chairs Yvonne Coady, Uni Victoria, Canada Center, USA, Randy Sobie, University of Victoria, Canada, Jukka Suomela, Aalto University, Finland Workshop: 22 August 2014 ACM SIGCOMM: 17-22 August 2014 #12;

  18. D39.3.1 (Final) Report on NLP-based CALL Workshop

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    NLP and CALL is primarily due to a divergence between computer scientists and didactics experts of codes, while for didactics experts, it is a system of forms and concepts. Currently, most language

  19. RoutingTG_5-31-07_call_minutes.rtf

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

    May 31, 2007 2:00 p.m.-3:30 p.m. EDT Conference Call Minutes Chair: Jay Jones (RW) Participants: Melissa Bailey ( CSG-NE), Jane Beetem (MO Dept. of Natural Resources), Kevin...

  20. U.S. Department of Energy to Host Press Call on Transition of...

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

    586 4940 U.S. Department of Energy to Host Press Call on Transition of Legacy Cleanup Work at Los Alamos National Laboratory WASHINGTON- On Wednesday, December 3, 2014, the Office...

  1. Anthem Cyber Attack: Information and Call-in Phone Number | Jefferson...

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

    Anthem Cyber Attack: Information and Call-in Phone Number Colleagues, As you may have heard by now, Anthem was the latest victim of a cyber attack. Anthem reports that they were...

  2. Date: 415/2010 11:26:19 AM Call #: 624.102854 C7395

    E-Print Network [OSTI]

    (a) a solid phase (porous medium), (b) at least two ?uid phases, and (c) interface (surface) phases. b?tween each two ?uid phases is called a capillary. WSIem.

  3. Marine renewable energy: potential benefits to biodiversity? An urgent call for research

    E-Print Network [OSTI]

    Exeter, University of

    Marine renewable energy: potential benefits to biodiversity? An urgent call for research Richard 1 Centre for Ecology and Conservation and Peninsula Research Institute for Marine Renewable Energy driver. In response, many governments have initiated programmes of energy production from renewable

  4. Energy Regulation, Roll Call Votes and Regional Resources: Evidence from Russia

    E-Print Network [OSTI]

    Grigoriadis, Theocharis N; Torgler, Benno

    2007-01-01T23:59:59.000Z

    Energy Regulation, Roll Call Votes and Regional Resources:Russian Duma deputies on energy regulation between 1994 andP370, P310, R110 energy regulation, energy roll law reform,

  5. R. P. Doerner, VLT Call, Jan. 17, 2011 Simulation measurements of tungsten fuzz in

    E-Print Network [OSTI]

    Diego, USA Work performed in collaboration with: US-EU Collaboration on Mixed-Material PMI Effects Diego R. P. Doerner, VLT Call, Jan. 17, 2011 W Temperature & PMI are coupled NAGDIS-II: He plasma D

  6. Appel d'offre Call for application Chaire Economie de l'innovation

    E-Print Network [OSTI]

    Rennes, Université de

    appel d'offre pour la création d'une chaire de recherche et de formationAppel d'offre ­ Call for application Chaire « Economie de l Economie et Management). Il pourra aussi faciliter les interactions de recherche

  7. Mon. Not. R. Astron. Soc. 320, 131138 (2001) Discs and the 10-mm silicate spectra of young stellar objects with non-

    E-Print Network [OSTI]

    Bowey, Janet

    Mon. Not. R. Astron. Soc. 320, 131±138 (2001) Discs and the 10-mm silicate spectra of young stellar and Taurus-Elias 7 (Haro6-10, GV Tau) is distinguished from foreground silicate absorption using a simple that of Elias 7 is optically thick. We suggest that HL Tau's optically thin component arises from silicate dust

  8. ALMA detection of a disc-dominated [C II] emission line at z=4.6 in the luminous QSO J1554+1937

    E-Print Network [OSTI]

    Kimball, Amy E; Lonsdale, Carol J; Macquart, J-P

    2015-01-01T23:59:59.000Z

    We present observations and analysis of an unusual [C II] emission line in the very luminous QSO SDSS J155426.16+193703.0 at z~4.6. The line is extremely broad (FWHM 735 km/s) and seems to have a flat-topped or double-peaked line profile. A velocity map of the line shows a gradient across the source that indicates large-scale rotation of star-forming gas. Together, the velocity map and line profile suggest the presence of a massive rotating disc with a dynamical mass M_dyn > 5x10^10 M_sun. Using the assumption of a rotating disc origin, we employ an empirical relation between galaxy disc circular velocity and bulge velocity dispersion (sigma) to estimate that sigma > 310 km/s, subject to a correction for the unknown disc inclination. This result implies that this source is consistent with the local M--sigma relation, or offset at most by an order of magnitude in black hole mass. In contrast, the assumption of a bulge origin for the [C II] emission line would lead to a conclusion that the black hole is nearly ...

  9. Models of thin discs and spheroidal haloes with masses in a linear relationship: mass estimates for NGC4389 and UGC6969

    E-Print Network [OSTI]

    Guillermo A. González; J. Ibáñez; Jerson I. Reina

    2011-11-16T23:59:59.000Z

    A family of models of thin discs and spheroidal haloes with masses in a linear relationship is presented. The models are obtained by considering the gravitational potential as the superposition of two independent components, a potential generated by the thin galactic disc and a potential generated by the spheroidal halo. The models leads to an expression for the circular velocity that can be adjusted very accurately to the observed rotation curves of some specific galaxies, in such a way that the models are stable against radial and vertical perturbations. Two particular models for galaxies NGC4389 and UGC6969 are obtained by adjusting the circular velocity with data taken from the recent paper by Verheijen & Sancici (2001). The values of the halo mass, the disc mass and the total mass for these two galaxies are computed in such a way that we obtain a very narrow interval of values for these quantities. Furthermore, the values of masses here obtained are in perfect agreement with the expected order of magnitude and with the relative order of magnitude between the halo mass and the disc mass.

  10. Better Buildings Neighborhood Program Workforce Peer Exchange Call: Recruiting a Local and Diverse Workforce and Mitigating Barriers to Entry Call Slides and Discussion Summary, August 25, 2011

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1, 20114, 2013 Better1,9, 2012Call5,

  11. Better Buildings Neighborhood Program Workforce Peer Exchange Call: Strategies for Aligning Program Demand with Contractors Seasonal Fluctuations Call Slides and Discussion Summary, June 7, 2012

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1, 20114, 2013 Better1,9, 2012Call5,7,

  12. Better Buildings Residential Network Marketing & Outreach Peer Exchange Call Series: Working with Schools Call Slides and Summary, April 24, 2014

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23, 2013 Better BuildingsJulyCall

  13. Better Buildings Residential Network Peer Exchange Call: Commercial and Multi-family Building Benchmarking and Disclosure, Call Slides, July 25, 2013

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call: Combining Solar and Home25,

  14. Better Buildings Residential Network Program Sustainability Mastermind Call: Targeted Workforce Recruitment, Training, and Success in the Market Call Slides and Discussion Summary, March 13, 2014

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call: Combining Solar and

  15. Better Buildings Residential Network Program Sustainability Peer Exchange Call Series: Collaborating with Utilities on Residential Energy Efficiency, Call Slides and Discussion Summary, June 12, 2014

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call: Combining Solar

  16. Better Buildings Residential Network Program Sustainability Peer Exchange Call Series: Community Readiness Assessments Call Slides and Discussion Summary, December 5, 2013

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call: Combining Solar Community

  17. Better Buildings Residential Network Program Sustainability Peer Exchange Call Series: Complementary Energy and Health Strategies Call Slides and Discussion Summary, April 10, 2014

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call: Combining Solar

  18. Better Buildings Residential Network Program Sustainability Peer Exchange Call Series: Coordinating Energy Efficiency with Disaster Resiliency and Response Call Slides and Discussion Summary, January 9, 2014

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call: Combining SolarCoordinating

  19. Better Buildings Residential Network Program Sustainability Peer Exchange Call Series: Coordinating Energy Efficiency with Water Conservation Services Call Slides and Discussion Summary September 11, 2014

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call: Combining

  20. Better Buildings Residential Network Program Sustainability Peer Exchange Call Series: Incorporating Behavior Change Efforts into Energy Efficiency Programs Call Slides and Discussion Summary, July 10, 2014

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call: CombiningIncorporating

  1. Better Buildings Residential Network Program Sustainability Peer Exchange Call Series: Incorporating Energy Efficiency into Disaster Recovery Efforts Call Slides and Discussion Summary, October 9, 2014

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call:

  2. Better Buildings Residential Network Program Sustainability Peer Exchange Call Series: Trends in Real Estate and Energy Efficiency Call Slides and Discussion Summary, November 7, 2013

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call:Trends in Real Estate and

  3. Better Buildings Residential Network Program Sustainability Peer Exchange Call Series: Update on Revenue Strategies Call Slides and Discussion Summary December 11, 2014

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call:Trends in Real Estate

  4. Better Buildings Residential Network Program Sustainability Peer Exchange Call Series: Voluntary Initiative: Partnering to Enhance Program Capacity Call Slides and Summary May 8, 2014

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call:Trends in Real

  5. Better Buildings Residential Network Program Sustainability Peer Exchange Call: Complementary State Policies for Energy Efficiency Programs Call Slides and Summary, July 18, 2013

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call:Trends in Real18, 2013

  6. Better Buildings Residential Network Program Sustainability Peer Exchange Call: Operating as a Prime Contractor Call Slides and Discussion Summary, May 9, 2013

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call:Trends in Real18,

  7. Better Buildings Residential Network Program Sustainability/Working with Utilities Peer Exchange Call: Working with Smaller Municipal Utilities Call Slides and Summary, June 27, 2013

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call:Trends in

  8. Better Buildings Residential Network Workforce/ Business Partners Peer Exchange Call Series: Home Performance Training & Mentoring: Lessons and Resources Call Slides and Discussion Summary, August 14, 2014

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call:Trends inWorkforce

  9. Better Buildings Residential Network Workforce/Business Partners Peer Exchange Call: Energy Advising Services in the Post-ARRA World Call Slides and Summary, June 27, 2013

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call:Trends

  10. Better Buildings Residential Network, Financing & Revenue Peer Exchange Call Series: Using Loan Performance Data to Inform Program Implementation, Call Slides and Discussion Summary, May 22, 2014

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call:Trends2, 2013 BetterUsing

  11. Better Buildings Residential Program Peer Exchange Call: How Can the Network Meet Your Needs? Call Slides and Meeting Summary February 27, 2014

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call:Trends2,

  12. Better Buildings Residential Workforce/ Business Partners Peer Exchange Call Series: Contractor Rating and Feedback Systems Call Slides and Discussion Summary, April 24, 2014

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call:Trends2, WebinarDepartment

  13. Title of PresentatioBetter Buildings Residential Network Workforce/Business Partners Peer Exchange Call Series: Contractor-Funded Incentives Call Slides and Discussion Summary, November 21, 2013

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn'tOriginEducationVideoStrategic|Industrial Sector,Department ThirdCostsComments onTribalTitle Call

  14. Proposal for the Award of a Contract, without a Call for Tenders, for the Overhaul of a Diesel Generator Set

    E-Print Network [OSTI]

    1995-01-01T23:59:59.000Z

    Proposal for the Award of a Contract, without a Call for Tenders, for the Overhaul of a Diesel Generator Set

  15. Call for Papers 9th Annual European Symposium on Algorithms ESA 2001

    E-Print Network [OSTI]

    Brodal, Gerth Stølting

    Call for Papers 9th Annual European Symposium on Algorithms ­ ESA 2001 BRICS, University of Aarhus, Denmark, August 28­31, 2001 Scope The Symposium covers research in the use, design, and analysis programming. ESA 2001 is spon- sored by BRICS and EATCS (the European Association for Theoretical Computer

  16. Call for Papers 5th Workshop on Algorithm Engineering { WAE 2001

    E-Print Network [OSTI]

    Brodal, Gerth Stølting

    Call for Papers 5th Workshop on Algorithm Engineering { WAE 2001 BRICS, University of Aarhus, Denmark, August 28{30, 2001 Scope The Workshop on Algorithm Engineering covers research in all aspects of future research. WAE 2001 is spon- sored by BRICS and EATCS (the European Association for Theoretical

  17. Call for Papers 5th Workshop on Algorithm Engineering WAE 2001

    E-Print Network [OSTI]

    Brodal, Gerth Stølting

    Call for Papers 5th Workshop on Algorithm Engineering ­ WAE 2001 BRICS, University of Aarhus, Denmark, August 28­30, 2001 Scope The Workshop on Algorithm Engineering covers research in all aspects of future research. WAE 2001 is spon- sored by BRICS and EATCS (the European Association for Theoretical

  18. Call for Papers 9th Annual European Symposium on Algorithms --ESA 2001

    E-Print Network [OSTI]

    Brodal, Gerth Stølting

    Call for Papers 9th Annual European Symposium on Algorithms -- ESA 2001 BRICS, University of Aarhus, Denmark, August 28--31, 2001 Scope The Symposium covers research in the use, design, and analysis of e. ESA 2001 is spon­ sored by BRICS and EATCS (the European Association for Theoretical Computer Science

  19. or call Mairi on 01877 389245 www.forestry.gov.uk/scotland

    E-Print Network [OSTI]

    or call Mairi on 01877 389245 www.forestry.gov.uk/scotland Would you like to help at your local forest Visitor Centre? Enjoy the forest, learn new skills, meet new people and be part of the Forestry like an application pack please contact: Mairi Buchanan, Volunteer Manager Forestry Commission Scotland

  20. Fine-Grained Power Modeling for Smartphones Using System Call Tracing

    E-Print Network [OSTI]

    Zhang, Ming

    Fine-Grained Power Modeling for Smartphones Using System Call Tracing Abhinav Pathak Purdue consumption of mobile applications. We observe that state- of-the-art, utilization-based power modeling correlates the (actual) utilization of a hardware component with its power state, and hence is insufficient

  1. he long-term economic forecast calls for the continuation of the

    E-Print Network [OSTI]

    Hemmers, Oliver

    T he long-term economic forecast calls for the continuation of the economic recovery in 2014 predicts a steady economic recovery for Southern Nevada from 2014 onward. The Las Vegas economy-Term Economic Forecast Figure 1: Total Employment (1990-2050) Source: Center for Business and Economic Research

  2. An Operational Account of Call-By-Value Minimal and Classical -calculus in "Natural

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    operational system essentially contains Plotkin's v rule and is necessary and sufficient for the evaluation-style (cps) semantics of a call-by-value -calculus, named v. Significant contributions were made first by the last authors to be complete with respect to Plotkin's cps semantics. In the same paper, Sabry

  3. ABOUT THURGOOD MARSHALL COLLEGE In accordance with the UCSD Master Plan, which called for the

    E-Print Network [OSTI]

    Tsien, Roger Y.

    ABOUT THURGOOD MARSHALL COLLEGE In accordance with the UCSD Master Plan, which called "Third College." Today, the academic programs housed in Thurgood Marshall College (Contemporary Black as committed leaders in a multicultural world. Thurgood Marshall College (so named in 1992 after the first

  4. Data Mining and MultiAgent Edited Book CALL FOR CHAPTERS

    E-Print Network [OSTI]

    Cao, Longbing

    Data Mining and MultiAgent Edited Book CALL FOR CHAPTERS On an Edited Book to Be Published by Springer in 2009 Data Mining and Multiagent Integration Editor: Longbing Cao Chapter Proposal Submission: December 15, 2008 Planned Publishing Date: July 2009 Introduction In the last decade, data mining

  5. Combining Financial Double Call Options with Real Options for Early Curtailment of Electricity Service

    E-Print Network [OSTI]

    Combining Financial Double Call Options with Real Options for Early Curtailment of Electricity@IEOR.Berkeley.edu Abstract In a competitive electricity market traditional demand side management options offering customers curtailable service at reduced rates are replaced by voluntary customer responses to electricity spot prices

  6. Questions? Call 540/231-8636 REQUEST FOR DIPLOMA REPLACEMENT/REPRINT

    E-Print Network [OSTI]

    Buehrer, R. Michael

    Questions? Call 540/231-8636 REQUEST FOR DIPLOMA REPLACEMENT/REPRINT PAGE 1 OF 1, NOVEMBER 2013 REQUEST FOR GRADUATE DIPLOMA REPLACEMENT/REPRINT Return your completed form to: Graduate School Graduate of the replacement diploma. Current graduate diplomas measure 11" by 14". Your diploma will be printed with the legal

  7. Microsoft PowerPoint - SpringOpsCallHandout27June2013 [Compatibility...

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

    27, 2013 2:00 - 3:00 p.m. To participate in the call please dial: (877) 336-1839 When prompted, enter access code: 1687421 B O N N E V I L L E P O W E R A D M I N I S T R A T I O N...

  8. Assuring Generation Adequacy through Call Option Obligations Shmuel S. Oren, Fellow IEEE

    E-Print Network [OSTI]

    Oren, Shmuel S.

    Assuring Generation Adequacy through Call Option Obligations Shmuel S. Oren, Fellow IEEE University-utility generators to bear investment and operating risks, and by requiring retailers and/or their customers to bear energy market, generators always offer supply at marginal cost but inframarginal profits (from scarcity

  9. ORIGINAL PAPER The diet of feral cats on islands: a review and a call for more

    E-Print Network [OSTI]

    Zavaleta, Erika

    Santa Cruz de La Palma, Canary Islands, Spain M. Nogales Island Ecology and Evolution Research Group (IPNA-CSIC), Astrofi´sico Francisco Sa´nchez 3, 38206 La Laguna Tenerife, Canary Islands, Spain BORIGINAL PAPER The diet of feral cats on islands: a review and a call for more studies E. Bonnaud

  10. Tri-County High School Exhibition Call for Entries Wayne State University

    E-Print Network [OSTI]

    Berdichevsky, Victor

    Tri-County High School Exhibition Call for Entries Wayne State University James Pearson Duffy for its Tri-County High School Exhibition. The exhibition dates are March 2 ­ March 23, 2012 counties. ABOUT THE GALLERY The Art Department Gallery hosts annual undergraduate exhibitions, provides

  11. Activate the nearest fire alarm pull station Call 911 to report the fire

    E-Print Network [OSTI]

    Azevedo, Ricardo

    as designated by emergency responders, well away from the building. Do not touch or disturb the objectActivate the nearest fire alarm pull station Call 911 to report the fire Notify and assist people not re-enter the building until authorized to do so by emergency personnel. When the fire alarm

  12. FWF OTKA Call for Lead Agency applications June 2014 Hungarian Scientific Research Fund (OTKA)

    E-Print Network [OSTI]

    Fuchs, Clemens

    1 FWF ­ OTKA Call for Lead Agency applications ­ June 2014 Hungarian Scientific Research Fund (OTKA input from both sides. Applications will be dealt with following the Lead Agency Principle. The application must be prepared in accordance with the formal guidelines of the Lead Agency. The Lead Agency

  13. Call for Papers 2014 BYU Conference on Family History and Genealogy

    E-Print Network [OSTI]

    Olsen Jr., Dan R.

    Call for Papers 2014 BYU Conference on Family History and Genealogy "Strengthening Ties That Bind for the 2014 BYU Conference on Family History and Genealogy which will be held Tuesday, July 29 through Friday and genealogy: Getting started in family history o Classes specifically designed for those who never have done

  14. Call for Papers 2013 BYU Conference on Family History and Genealogy

    E-Print Network [OSTI]

    Martinez, Tony R.

    Call for Papers 2013 BYU Conference on Family History and Genealogy "Strengthening Ties That Bind for the 2013 BYU Conference on Family History and Genealogy which will be held Tuesday, July 30 through Friday and helpful information in the following areas of family history and genealogy: · Getting started in family

  15. Why Citizen Science? Public participation in scientific research, commonly called citizen

    E-Print Network [OSTI]

    Hall, Sharon J.

    Findings Why Citizen Science? Public participation in scientific research, commonly called citizen as the citizen science type of PPSR when compared against typologies (Fig 2). Furthermore, 82% of projects that 71% of PPSR projects were in the citizen science model and focused on conservation and/or ecology

  16. MATH 121 SYLLABUS FALL 1997 Lecture Time Room Instructor Office Phone Call No.

    E-Print Network [OSTI]

    Baldwin, John T.

    Office Phone Call No. MWF 8 LC-D5 Stinespring624 SEO 3-0368 61306 MWF 9 LC-E1 Baldwin 417SEO 3-2149 61231 MWF 9 LC-D4 Gray 508 SEO 6-4828 31494 MWF 2 LC-D4 Tartakoff 516 SEO 6-2440 61440 MWF

  17. Call for expression of interest EU-Brazil Technology and Innovation Forum

    E-Print Network [OSTI]

    Call for expression of interest EU-Brazil Technology and Innovation Forum Participation to B2B targeting research and innovation actors. Among them, this year the EU-Brazil Technology and Innovation and Innovation Forum The EU-Brazil Technology and Innovation Forum is organized by the B.BICE+ consortium

  18. Duval County Extension -April 2011 Call 904-387-8850 to register or for more information

    E-Print Network [OSTI]

    Watson, Craig A.

    Kinney for High School Financial Planning Program and On My Own Financial Simulation. April 2 Plant Clinics, 10 am://www.solutionsforyourlife.com/ Master Gardeners will host Plant Clinics at nurseries and garden centers Saturdays, April 2 & April 9 10 & Gardens Call 757-4463 Ext. 122 to pre-register Power Against Financial Fraud April 27 10 - 11:30 am

  19. The strategic allocation of cyclically calling vessels for multi-terminal container operators

    E-Print Network [OSTI]

    Armbruster, Dieter

    The strategic allocation of cyclically calling vessels for multi-terminal container operators M.P.M. Hendriks , D. Armbruster, , M. Laumanns , E. Lefeber , J.T. Udding Abstract We consider a terminal operator, who provides his logistics services of container handling at multiple terminals within the same port

  20. SEKE2015 Call For Papers The 27th International Conference on Software Engineering and Knowledge Engineering

    E-Print Network [OSTI]

    Xu, Haiping

    Software Safety Software Security Software Engineering Case Study and Experience Reports Web-Based ToolsSEKE2015 Call For Papers The 27th International Conference on Software Engineering and Knowledge Engineering www.ksi.edu/seke/seke15.html (Alternate website: ksiresearchorg.ipage.com/seke/seke15.html

  1. Artificial neural network discrimination of black-capped chickadee (Poecile atricapillus) call notes

    E-Print Network [OSTI]

    Dawson, Michael

    Artificial neural network discrimination of black-capped chickadee (Poecile atricapillus) call; revised 11 April 2006; accepted 12 May 2006 Artificial neural networks were trained to discriminate number s : 43.80Ka., 43.80.Lb, 43.80.Jz JAS Pages: 1111­1117 I. INTRODUCTION An artificial neural network

  2. Call for papers Valuation Studies is a new open access journal connecting several vibrant

    E-Print Network [OSTI]

    Zhao, Yuxiao

    Call for papers Valuation Studies is a new open access journal connecting several vibrant research elds working on the study of valuation as a social practice. To engage scholars with various backgrounds and orientations in discussions about valuation, the journal welcomes papers in different forms

  3. North Pacific right whale calling behavior and habitat characterization in the southeastern Bering Sea

    E-Print Network [OSTI]

    Munger, Lisa Marie

    2007-01-01T23:59:59.000Z

    05-06) and 124 days at M4 (2005-06), except in 2004, whentime scale of the plots. In 2005-06, acoustic recording wasfrom M2. C) Calls/day in 2005-06 and oceanographic data both

  4. Optimal Code Assignment and Call Admission Control for OVSF-CDMA Systems Constrained by Blocking Probabilities

    E-Print Network [OSTI]

    Lee, Daniel C.

    the Markov Decision Process and linear programming. The performance of each scheme is numerically evaluatedOptimal Code Assignment and Call Admission Control for OVSF-CDMA Systems Constrained by Blocking code assignment schemes for OVSF-CDMA systems is investigated, and the optimal fixed and dynamic code

  5. Robot-to-Robot Nurturing: A Call to the Research Community

    E-Print Network [OSTI]

    Schlupp, Ingo

    Robot-to-Robot Nurturing: A Call to the Research Community Mark Woehrer School of Computer Science and artificial systems, how robot-to-robot (R2R) nurturing is related to developmental robotics including epigenetic and morphogenetic robotics, why R2R nurturing should be considered an important topic, and why we

  6. Call for Papers The First International Workshop on Smart Cities and Urban Informatics

    E-Print Network [OSTI]

    Ngai, Edith Cheuk-Han

    Call for Papers The First International Workshop on Smart Cities and Urban Informatics (in conjunction with IEEE INFOCOM 2015) http://user.it.uu.se/~eding810/SmartCity2015/ Scope and Topics of Interest and communication systems play a critical role in building smart cities and supporting comprehensive urban

  7. Call/Return Protocols observe: register set used for efficient access

    E-Print Network [OSTI]

    Chamberlain, Roger

    to maintain register state in calling routine so registers can be effectively used need to save registers is responsible for saving? One approach: caller save registers · Value in %ecx is set in main, not in foo #12;10/4/2011 2 Caller save protocol · Only save what needs to be kept unaltered ++ · Don't know if callee might

  8. Call (603) 862-SAFE (7233) Or toll free (888) 271-7233

    E-Print Network [OSTI]

    New Hampshire, University of

    , relationship abuse, stalk- ing and to those who care about them. Trained advocates are on call 24-hours a day AND RELATIONSHIP ABUSE: MYTH: Anyonewhodressesacertainway,acts flirtatious, and people with no previous rela- tionship. People of all sexual orientations are protected. MYTH: Abuse isn

  9. Figure 5 : Inversed attenuation tomography The Fresnel volume thus defined, also called Frchet kernel

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Figure 5 : Inversed attenuation tomography The Fresnel volume thus defined, also called Fréchet system with the LSQR algorithm : Because the size of the Fresnel volume thus defined is dependent propose to compute the Fresnel weights for a monochromatic wave, increasing its frequency at each step

  10. Office of Residential Life and Learning, South Hall Call (617) 627-3248

    E-Print Network [OSTI]

    Tufts University

    Office of Residential Life and Learning, South Hall Call (617) 627-3248 Fax (617) 627-3929 Email Commencement Week must have their supervisor or coach submit a group or team list to Residential Life and Learning by 5 p.m. on Friday, April 15, 2011. I understand that the Office of Residential Life and Learning

  11. 36 SCIENTIFIC AMERICAN July 2008 In a dramatic call to action in April, United Nations

    E-Print Network [OSTI]

    OPINION 36 SCIENTIFIC AMERICAN July 2008 In a dramatic call to action in April, United Nations on an accelerated timeta- ble. The international system is a congeries of overlapping public and private effectively take a shared action. Success will enable us to consider similarly urgent challenges in food

  12. Top UN officials call on hold-out States to ratify treaty banning nuclear tests

    E-Print Network [OSTI]

    diseases, poisoned the food chain and contaminated the water and its ecosystems; these effects are still that have not yet signed or ratified the treaty to do so as a matter of priority," he added calling in Kazakhstan, Mr. Ban recalled visiting "the scene of this dark chapter in human history," and stressed his

  13. Call for papers and posters Energy and people: futures, complexity and challenges

    E-Print Network [OSTI]

    Oxford, University of

    explore future trends in energy practices, emphasise the human dimension and which: 1) Challenge wish to explore linkages between energy and wider themes, such as: · Equity · Consumption patternsCall for papers and posters Energy and people: futures, complexity and challenges The Lower Carbon

  14. 2013 Call for Proposals SUSTAINABILITY INNOVATION IN RESEARCH AND EDUCATION (SIRE)

    E-Print Network [OSTI]

    Wisconsin at Madison, University of

    to capture campus- wide sustainability metrics on the following issues: · Food systems · Energy usage2013 Call for Proposals SUSTAINABILITY INNOVATION IN RESEARCH AND EDUCATION (SIRE) Awards Program Office of Sustainability University of Wisconsin-Madison www.sustainability.wisc.edu The Office

  15. Call for Nominations to the WTERT/SUR 2010 Awards -February 22, 2010

    E-Print Network [OSTI]

    Columbia University

    Call for Nominations to the WTERT/SUR 2010 Awards - February 22, 2010 The WTERT 2010 Bi-8 at Columbia University in New York City. Two Awards will be presented at this meeting to -World City Closest Awards has been set at above 250,000. Please provide any other information you may have as to why

  16. INTRODUCTION The energy transition within cells, called metabolism, is a basic

    E-Print Network [OSTI]

    Kramarz, Paulina

    391 INTRODUCTION The energy transition within cells, called metabolism, is a basic characteristic-387 Kraków, Poland, 2 INRA, UR 544, Unité de Génétique des Poissons, F-78350 Jouy en Josas, France, 3 INRA

  17. OPEN CALL FOR EXPRESSIONS OF INTEREST For candidates for the position of

    E-Print Network [OSTI]

    OPEN CALL FOR EXPRESSIONS OF INTEREST For candidates for the position of Nominee ITER Principal be an advantage. Languages: a thorough knowledge of English is essential and a working knowledge of French would programme. Interested candidates should send, either by e-mail or surface mail, their applications

  18. Mining Call and Mobility Data to Improve Paging Efficiency in Cellular Networks

    E-Print Network [OSTI]

    , Data Mining, CDMA 1. INTRODUCTION Location management is a key component in the operation of cellularMining Call and Mobility Data to Improve Paging Efficiency in Cellular Networks Hui Zang Sprint a different, data-driven approach in how we design and evaluate our solution. Specifically, we mine more than

  19. Call for Participation in a Workshop on Inter-Infrastructure Risks Due to

    E-Print Network [OSTI]

    Johnson, Chris

    that will help distribute renewable energy through to the SESAR proposals for European software integrationCall for Participation in a Workshop on Inter-Infrastructure Risks Due to Natural Hazards systems (e.g., transport, water supply and sewers, energy, communications). These interdependencies

  20. A Wakeup Call for Internet Monitoring Systems: The Case for Distributed Triggers

    E-Print Network [OSTI]

    is not perceived to be a DDoS attack, e.g., the aggregate traffic to any destination from a set of nodes runningA Wakeup Call for Internet Monitoring Systems: The Case for Distributed Triggers Ankur Jain is to continually record system state (e.g., to study traffic pat- terns in a network) or to obtain an instantaneous

  1. RA After Hours On Call (971) 246-1388 Your Guide to

    E-Print Network [OSTI]

    Latiolais, M. Paul

    for the resident to pick up at the move-in station. Laundry Laundry facilities are located on odd-numbered floors is on for an extended amount of time, please notify the Help desk or the RA on call. If you leave trash, abandoned

  2. The dynamical evolution of low-mass hydrogen-burning stars, brown dwarfs and planetary-mass objects formed through disc fragmentation

    E-Print Network [OSTI]

    Li, Yun; Stamatellos, D; Goodwin, S P

    2015-01-01T23:59:59.000Z

    Theory and simulations suggest that it is possible to form low-mass hydrogen-burning stars, brown dwarfs and planetary-mass objects via disc fragmentation. As disc fragmentation results in the formation of several bodies at comparable distances to the host star, their orbits are generally unstable. Here, we study the dynamical evolution of these objects. We set up the initial conditions based on the outcomes of the SPH simulations of Stamatellos & Whitworth, and for comparison we also study the evolution of systems resulting from lower-mass fragmenting discs. We refer to these two sets of simulations as set 1 and set 2. At 10 Myr, approximately half of the host stars have one companion left, and approximately 22% (set 1) to 9.8% (set 2) of the host stars are single. Systems with multiple secondaries in relatively stable configurations are common (about 30% and 44%, respectively). The majority of the companions are ejected within 1 Myr with velocities mostly below 5 km/s, with some runaway escapers with ve...

  3. CO mass upper limits in the Fomalhaut ring - the importance of NLTE excitation in debris discs and future prospects with ALMA

    E-Print Network [OSTI]

    Matrà, L; Wyatt, M C; Dent, W R F

    2014-01-01T23:59:59.000Z

    In recent years, gas has been observed in an increasing number of debris discs, though its nature remains to be determined. Here, we analyse CO molecular excitation in optically thin debris discs, and search ALMA Cycle-0 data for CO J=3-2 emission in the Fomalhaut ring. No significant line emission is observed; we set a 3-$\\sigma$ upper limit on the integrated line flux of 0.16 Jy km s$^{-1}$. We show a significant dependency of the CO excitation on the density of collisional partners $n$, on the gas kinetic temperature $T_k$ and on the ambient radiation field $J$, suggesting that assumptions widely used for protoplanetary discs (e.g. LTE) do not necessarily apply to their low density debris counterparts. When applied to the Fomalhaut ring, we consider a primordial origin scenario where H$_2$ dominates collisional excitation of CO, and a secondary origin scenario dominated by e$^-$ and H$_2$O. In either scenario, we obtain a strict upper limit on the CO mass of 4.9 $\\times$ 10$^{-4}$ M$_{\\oplus}$. This arises...

  4. Insights into gas heating and cooling in the disc of NGC 891 from Herschel far-infrared spectroscopy

    E-Print Network [OSTI]

    Hughes, T M; Schirm, M R P; Parkin, T J; De Looze, I; Wilson, C D; Bendo, G J; Baes, M; Fritz, J; Boselli, A; Cooray, A; Cormier, D; Karczewski, O ?; Lebouteiller, V; Lu, N; Madden, S C; Spinoglio, L; Viaene, S

    2014-01-01T23:59:59.000Z

    We present Herschel PACS and SPIRE spectroscopy of the most important far-infrared cooling lines in the nearby edge-on spiral galaxy, NGC 891: [CII] 158 $\\mu$m, [NII] 122, 205 $\\mu$m, [OI] 63, 145 $\\mu$m, and [OIII] 88 $\\mu$m. We find that the photoelectric heating efficiency of the gas, traced via the ([CII]+[OII]63)/$F_{\\mathrm{TIR}}$ ratio, varies from a mean of 3.5$\\times$10$^{-3}$ in the centre up to 8$\\times$10$^{-3}$ at increasing radial and vertical distances in the disc. A decrease in ([CII]+[OII]63)/$F_{\\mathrm{TIR}}$ but constant ([CII]+[OI]63)/$F_{\\mathrm{PAH}}$ with increasing FIR colour suggests that polycyclic aromatic hydrocarbons (PAHs) may become important for gas heating in the central regions. We compare the observed flux of the FIR cooling lines and total IR emission with the predicted flux from a PDR model to determine the gas density, surface temperature and the strength of the incident far-ultraviolet (FUV) radiation field, $G_{0}$. Resolving details on physical scales of ~0.6 kpc, a p...

  5. The rise and fall of stellar discs across the peak of cosmic star formation history: mergers versus smooth accretion

    E-Print Network [OSTI]

    Welker, Charlotte; Devriendt, Julien; Pichon, Christophe; Kaviraj, Sugata; Peirani, Sebastien

    2015-01-01T23:59:59.000Z

    Building galaxy merger trees from a state-of-the-art cosmological hydrodynamics simulation, Horizon-AGN, we perform a statistical study of how mergers and smooth accretion drive galaxy morphologic properties above $z > 1$. More specifically, we investigate how stellar densities, effective radii and shape parameters derived from the inertia tensor depend on mergers of different mass ratios. We find strong evidence that smooth accretion tends to flatten small galaxies over cosmic time, leading to the formation of disks. On the other hand, mergers, and not only the major ones, exhibit a propensity to puff up and destroy stellar disks, confirming the origin of elliptical galaxies. We also find that elliptical galaxies are more susceptible to grow in size through mergers than disc galaxies with a size-mass evolution $r \\prop M^{1.2}$ instead of $r \\prop M^{-0.5} - M^{0.5}$ depending on the merger mass ratio. The gas content drive the size-mass evolution due to merger with a faster size growth for gas-poor galaxies...

  6. The UK Infrared Telescope M33 monitoring project. IV. Variable red giant stars across the galactic disc

    E-Print Network [OSTI]

    Javadi, Atefeh; van Loon, Jacco Th; Khosroshahi, Habib; Golabatooni, Najmeh; Mirtorabi, Mohammad Taghi

    2014-01-01T23:59:59.000Z

    We have conducted a near-infrared monitoring campaign at the UK InfraRed Telescope (UKIRT), of the Local Group spiral galaxy M33 (Triangulum). The main aim was to identify stars in the very final stage of their evolution, and for which the luminosity is more directly related to the birth mass than the more numerous less-evolved giant stars that continue to increase in luminosity. In this fourth paper of the series, we present a search for variable red giant stars in an almost square degree region comprising most of the galaxy's disc, carried out with the WFCAM instrument in the K band. These data, taken during the period 2005--2007, were complemented by J- and H-band images. Photometry was obtained for 403 734 stars in this region; of these, 4643 stars were found to be variable, most of which are Asymptotic Giant Branch (AGB) stars. The variable stars are concentrated towards the centre of M33, more so than low-mass, less-evolved red giants. Our data were matched to optical catalogues of variable stars and ca...

  7. Mid-infrared spectroscopy of SVS13: Silicates, quartz and SiC in a protoplanetary disc

    E-Print Network [OSTI]

    Fujiyoshi, Takuya; Moore, Toby J T

    2015-01-01T23:59:59.000Z

    We present $N$-band (8$-$13 $\\mu$m) spectroscopic observations of the low-mass, embedded pre-main-sequence close binary system SVS13. Absorption features are clearly detected which are attributable to amorphous silicates, crystalline forsterite, crystalline enstatite and annealed SiO$_{2}$. Most intriguingly, a major component of the dust in the envelope or disc around SVS13 appears to be SiC, required to model adequately both the total intensity and polarisation spectra. Silicon carbide is a species previously detected only in the spectra of C-rich evolved star atmospheres, wherein it is a dust condensate. It has not been unambiguously identified in the interstellar medium, and never before in a molecular cloud, let alone in close proximity to a forming star. Yet pre-Solar grains of SiC have been identified in meteorites, possibly suggesting an interesting parallel between SVS13 and our own Solar-System evolution. The uniqueness of the spectrum suggests that we are either catching SVS13 in a short-lived evol...

  8. I Can't Believe It's Not Toothpaste! Poison Control Center Calls Regarding Dental and Oral-Care Products

    E-Print Network [OSTI]

    Suchard, Jeffrey R

    2003-01-01T23:59:59.000Z

    of the American Association of Poison Control Ceilters ToxicIt's Not Toothpaste! Poison Control Center Calls Regardingjsuchard@uci.edu INTRODUCTION Poison Control Centers receive

  9. Flow tests of the Gladys McCall well. Appendix A, Gladys McCall Site (Cameron Parish, LA): Final report, October 1985--October 1990

    SciTech Connect (OSTI)

    Randolph, P.L.; Hayden, C.G.; Rogers, L.A. [Institute of Gas Technology, Chicago, IL (United States)

    1992-04-01T23:59:59.000Z

    This report pulls together the data from all of the geopressured-geothermal field research conducted at the Gladys McCall well. The well produced geopressured brine containing dissolved natural gas from the Lower Miocene sands at a depth of 15,150 to 16,650 feet. More than 25 million barrels of brine and 727 million standard cubic feet of natural gas were produced in a series of flow tests between December 1982 and October 1987 at various brine flow rates up to 28,000 barrels per day. Initial short-term flow tests for the Number 9 Sand found the permeability to be 67 to 85 md (millidarcies) for a brine volume of 85 to 170 million barrels. Initial short-term flow tests for the Number 8 Sand found a permeability of 113 to 132 md for a reservoir volume of 430 to 550 million barrels of brine. The long-term flow and buildup test of the Number 8 Sand found that the high-permeability reservoir connected to the wellbore (measured by the short-term flow test) was connected to a much larger, low-permeability reservoir. Numerical simulation of the flow and buildup tests required this large connected reservoir to have a volume of about 8 billion barrels (two cubic miles of reservoir rock) with effective permeabilities in the range of 0.2 to 20 md. Calcium carbonate scale formation in the well tubing and separator equipment was a problem. During the first 2 years of production, scale formation was prevented in the surface equipment by injection of an inhibitor upstream of the choke. Starting in 1985, scale formation in the production tubing was successfully prevented by injecting inhibitor ``pills`` directly into the reservoir. Corrosion and/or erosion of surface piping and equipment, as well as disposal well tubing, was also significant.

  10. Call for Follow-Up Observations of the Dynamically Changing Triple Star KIC 2835289

    E-Print Network [OSTI]

    Conroy, Kyle; Stassun, Keivan; Orosz, Jerome

    2015-01-01T23:59:59.000Z

    KIC 2835289 is a triple stellar system that consists of an inner ellipsoidal variable with an orbital period of ~0.86 days and an outer star that eclipses the inner pair every ~750 days. Two eclipse events were observed by the Kepler mission, but they do not fully constrain our photodynamical models. The next eclipse event will occur on May 14 UT, and we solicit community involvement to follow it up from the ground. All details are available in the attached call. Please contact the authors to join the follow-up campaign.

  11. Better Buildings Residential Network Peer Exchange Call: Combining Solar and Home Performance Services, Call Slides and Discussion Summary, December 11, 2014Better Buildings Residential Network Peer Exchange Call: Combining Solar and Home Performance Services, Call Slides and Discussion Summary, December 11, 2014

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call: Combining Solar and Home

  12. Better Buildings Residential Network: Lessions Learned: Peer Exchange Calls No. 2

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call:Trends2, 2013 discuss

  13. Better Buildings Residential Network: Lessons Learned: Peer Exchange Calls … No. 3

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call:Trends2, 2013

  14. Better Buildings Workforce Peer Exchange Quality Assurance Strategies Call Slides and Discussion Summary, November 17, 2011

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: The FutureCommentsEnergy Christopher|for1,23,Call:Trends2,StateWorkforce

  15. LANS Venture Acceleration Fund announces "Call for Ideas"

    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 for4,645U.S. DOE Office of Science (SC)Integrated Codes |Is Your Home as ReadyAppointedKyungmin2010SciencesLANS BoardCall for

  16. FY 09 Lab Call: Research & Assessment for MHK Development | Department of

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

    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 on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't YourTransport in Representative GeologicReportingEnergy3,Energy FY 09 Lab Call: Research

  17. Microsoft Word - Pace Call n Ride handout for NEO and webpage march2015.docx

    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 for4,645U.S. DOE Office of Science (SC)Integrated Codes |IsLove Your1 SECTION A. Project0Central Helium7,QRPAPace Call-n-Ride

  18. Worker performance and ventilation in a call center: Analyses of work performance data for registered nurses

    SciTech Connect (OSTI)

    Federspiel, C.C.; Fisk, W.J.; Price, P.N.; Liu, G.; Faulkner, D.; Dibartolomeo, D.L.; Sullivan, D.P.; Lahiff, M.

    2004-05-01T23:59:59.000Z

    We investigated the relationship between ventilation rates and individual work performance in a call center, and controlled for other factors of the indoor environment. We randomized the position of the outdoor air control dampers, and measured ventilation rate, differential (indoor minus outdoor) carbon dioxide ({Delta}CO{sub 2}) concentration, supply air velocity, temperature, humidity, occupant density, degree of under-staffing, shift length, time of day, and time required to complete two different work performance tasks (talking with clients and post-talk wrap-up to process information). {Delta}CO{sub 2} concentrations ranged from 13 to 611 ppm. We used multi-variable regression to model the association between the predictors and the responses. We found that agents performed talk tasks fastest when the ventilation rate was highest, but that the relationship between talk performance and ventilation was not strong or monotonic. We did not find a statistically significant association between wrap-up performance and ventilation rate. Agents were slower at the wrap-up task when the temperature was high (>25.4 C). Agents were slower at wrap-up during long shifts and when the call center was under-staffed.

  19. On the behaviour of single scale hard small $x$ processes in QCD near the black disc limit

    E-Print Network [OSTI]

    B. Blok; L. Frankfurt

    2006-03-08T23:59:59.000Z

    We argue that at sufficiently small Bjorken $x$ where pQCD amplitude rapidly increases with energy and violates probability conservation the shadowing effects in the single-scale small $x$ hard QCD processes can be described by an effective quantum field theory of interacting quasiparticles. The quasiparticles are the perturbative QCD ladders. We find, within the WKB approximation, that the smallness of the QCD coupling constant ensures the hierarchy among many-quasiparticle interactions evaluated within physical vacuum and in particular, the dominance in the Lagrangian of the triple quasiparticle interaction. It is explained that the effective field theory considered near the perturbative QCD vacuum contains a tachyon relevant for the divergency of the perturbative QCD series at sufficiently small $x$. We solve the equations of motion of the effective field theory within the WKB approximation and find the physical vacuum and the transitions between the false (perturbative) and physical vacua. Classical solutions which dominate transitions between the false and physical vacua are kinks that cannot be decomposed into perturbative series over the powers of $\\alpha_s$. These kinks lead to color inflation and the Bose-Einstein condensation of quasiparticles. The account of the quantum fluctuations around the WKB solution reveals the appearance of the "massless" particles-- "phonons". It is explained that "phonons" are relevant for the black disc behaviour of small $x$ processes, leading to a Froissart rise of the cross-section. The condensation of the ladders produces a color network occupying a "macroscopic" longitudinal volume. We discuss briefly the possible detection of new QCD effects.

  20. A near-infrared interferometric survey of debris disc stars. II. CHARA/FLUOR observations of six early-type dwarfs

    E-Print Network [OSTI]

    O. Absil; E. Di Folco; A. Merand; J. -C. Augereau; V. Coude du Foresto; D. Defrere; P. Kervella; J. P. Aufdenberg; M. Desort; D. Ehrenreich; A. -M. Lagrange; G. Montagnier; J. Olofsson; T. A. ten Brummelaar; H. A. McAlister; J. Sturmann; L. Sturmann; N. H. Turner

    2008-06-30T23:59:59.000Z

    High-precision interferometric observations of six early-type main sequence stars known to harbour cold debris discs have been obtained in the near-infrared K band with the FLUOR instrument at the CHARA Array. The measured squared visibilities are compared to the expected visibility of the stellar photospheres based on theoretical photospheric models taking into account rotational distortion, searching for potential visibility reduction at short baselines due to circumstellar emission. Our observations bring to light the presence of resolved circumstellar emission around one of the six target stars (zeta Aql) at the 5 sigma level. The morphology of the emission source cannot be directly constrained because of the sparse spatial frequency sampling of our interferometric data. Using complementary adaptive optics observations and radial velocity measurements, we find that the presence of a low-mass companion is a likely origin for the excess emission. The potential companion has a K-band contrast of four magnitudes, a most probable mass of about 0.6 Msun, and is expected to orbit between about 5.5 AU and 8 AU from its host star assuming a purely circular orbit. Nevertheless, by adjusting a physical debris disc model to the observed Spectral Energy Distribution of the zeta Aql system, we also show that the presence of hot dust within 10 AU from zeta Aql, producing a total thermal emission equal to 1.69 +- 0.31% of the photospheric flux in the K band, is another viable explanation for the observed near-infrared excess. Our re-interpretation of archival near- to far-infrared photometric measurements shows however that cold dust is not present around zeta Aql at the sensitivity limit of the IRS and MIPS instruments onboard Spitzer, and urges us to remove zeta Aql from the category of bona fide debris disc stars.

  1. no pedestrian call during some cycles. It is not a problem if the required vehicle phase split is greater than the pedestrian Walk plus

    E-Print Network [OSTI]

    Tian, Zong Z.

    Xin Cheng, Zong Z. Tian, and Hongchao Liu 125 For an actuated signalized intersection, pedestrian calls

  2. HPI Future SOC Lab: Call for Projects Next generation technology, such as multicore CPUs as well as increasing

    E-Print Network [OSTI]

    Weske, Mathias

    - Memory Computing Technology (SAP HANA). The SAP Business ByDesign systemHPI Future SOC Lab: Call for Projects Next generation technology, such as multicore, developers of service-oriented computing systems have to understand

  3. Spring Creek Project for Ideas, Nature, and the Written Word Call for Nominations: Graduate Student Research and Writing Retreat

    E-Print Network [OSTI]

    Grünwald, Niklaus J.

    Spring Creek Project for Ideas, Nature, and the Written Word Call for Nominations: Graduate Student on a collaborative project or two graduate students who each have individual projects are invited to nominate graduate students in the humanities or environmental sciences

  4. Type II Cepheids in the Milky Way disc. Chemical composition of two new W Vir stars: DD Vel and HQ Car

    E-Print Network [OSTI]

    Lemasle, B; Bono, G; François, P; Saviane, I; Yegorova, I; Genovali, K; Inno, L; Galazutdinov, G; da Silva, R

    2015-01-01T23:59:59.000Z

    A robust classification of Cepheids into their different sub-classes and, in particular, between classical and Type II Cepheids, is necessary to properly calibrate the period-luminosity relations and for populations studies in the Galactic disc. Type II Cepheids are, however, very diverse, and classifications based either on intrinsic (period, light curve) or external parameters (e.g., [Fe/H], |z|) do not provide a unique classification. We want to ascertain the classification of two Cepheids, HQ Car and DD Vel, that are sometimes classified as classical Cepheids and sometimes as Type II Cepheids. To achieve this goal, we examine both their chemical composition and the presence of specific features in their spectra. We find emission features in the H{\\alpha} and in the 5875.64 {\\AA} He I lines that are typical of W Vir stars. The [Na/Fe] (or [Na/Zn]) abundances are typical of thick-disc stars, while BL Her stars are Na-overabundant ([Na/Fe]>+0.5 dex). Finally, the two Cepheids show a possible (HQ Car) or prob...

  5. Empirical Performance Model-Driven Data Layout Optimization and Library Call Selection for Tensor Contraction Expressions

    SciTech Connect (OSTI)

    Lu, Qingda; Gao, Xiaoyang; Krishnamoorthy, Sriram; Baumgartner, Gerald; Ramanujam, J.; Sadayappan, Ponnuswamy

    2012-03-01T23:59:59.000Z

    Empirical optimizers like ATLAS have been very effective in optimizing computational kernels in libraries. The best choice of parameters such as tile size and degree of loop unrolling is determined by executing different versions of the computation. In contrast, optimizing compilers use a model-driven approach to program transformation. While the model-driven approach of optimizing compilers is generally orders of magnitude faster than ATLAS-like library generators, its effectiveness can be limited by the accuracy of the performance models used. In this paper, we describe an approach where a class of computations is modeled in terms of constituent operations that are empirically measured, thereby allowing modeling of the overall execution time. The performance model with empirically determined cost components is used to perform data layout optimization together with the selection of library calls and layout transformations in the context of the Tensor Contraction Engine, a compiler for a high-level domain-specific language for expressing computational models in quantum chemistry. The effectiveness of the approach is demonstrated through experimental measurements on representative computations from quantum chemistry.

  6. New interpretation of the so-called Nubian strata in northeast Africa

    SciTech Connect (OSTI)

    Klitzsch, E.H.; Squyres, C.H.

    1988-08-01T23:59:59.000Z

    Stratigraphical interpretation of the so-called Nubian Sandstone of Egypt and northern Sudan have led to new ideas on the structural and paleogeographical development of northeast Africa. The strata formerly comprised under the term Nubian Sandstone include sediments from Cambrian to Paleocene age. Based on field work and paleontological investigations during the last 10 years, these strata can be subdivided into three major cycles, each characterizing a certain structural situation of northeast Africa. The first or Paleozoic cycle comprises strata of Cambrian to Early Carboniferous age. These strata were deposited during a period of generally northern dip of northeast Africa; continental sediments transported northward interfinger with marine strata resulting from southward transgressions. Sediments of the second cycle were deposited during and after Gondwana and northern continents collided, which caused updoming of large areas of Egypt and bordering areas to the west and east. As a result, most of Egypt became subject to erosion; transgressions remained near the present northern edge of the continent, and purely continental deposition took place in northern Sudan and bordering areas in Chad and Libya. The resulting strata are similar to the Karroo of East Africa. Strata of the third cycle were deposited after Pangea began to disintegrate. Northeast Africa now had a generally northern dip again, and consequently deposition was controlled - as during the first cycle - by northward drainage and southward transgressions. This last cycle began during Late Jurassic time.

  7. PRELIMINARY DATA CALL REPORT ADVANCED BURNER REACTOR START UP FUEL FABRICATION FACILITY

    SciTech Connect (OSTI)

    S. T. Khericha

    2007-04-01T23:59:59.000Z

    The purpose of this report is to provide data for preparation of a NEPA Environmental Impact Statement in support the U. S. Department of Energy (DOE) Global Nuclear Energy Partnership (GNEP). One of the GNEP objectives is to reduce the inventory of long lived actinide from the light water reactor (LWR) spent fuel. The LWR spent fuel contains Plutonium (Pu) -239 and other transuranics (TRU) such as Americium-241. One of the options is to transmute or burn these actinides in fast neutron spectra as well as generate the electricity. A sodium-cooled Advanced Recycling Reactor (ARR) concept has been proposed to achieve this goal. However, fuel with relatively high TRU content has not been used in the fast reactor. To demonstrate the utilization of TRU fuel in a fast reactor, an Advanced Burner Reactor (ABR) prototype of ARR is proposed, which would necessarily be started up using weapons grade (WG) Pu fuel. The WG Pu is distinguished by relatively highest proportions of Pu-239 and lesser amount of other actinides. The WG Pu will be used as the startup fuel along with TRU fuel in lead test assemblies. Because such fuel is not currently being produced in the US, a new facility (or new capability in an existing facility) is being considered for fabrication of WG Pu fuel for the ABR. This report is provided in response to ‘Data Call’ for the construction of startup fuel fabrication facility. It is anticipated that the facility will provide the startup fuel for 10-15 years and will take to 3 to 5 years to construct.

  8. MODELLING A CIRCUMSTELLAR DISC TRACED BY METHANOL MASERS. M. R. Pestalozzi, School of Physics, Astronomy and Mathematics, Univ. of Hertfordshire, AL9 10AB Hatfield, UK (michele@star.herts.ac.uk), M. Elitzur, Univ. of

    E-Print Network [OSTI]

    De Buizer, James Michael

    MODELLING A CIRCUMSTELLAR DISC TRACED BY METHANOL MASERS. M. R. Pestalozzi, School of Physics-Planck Institut f¨ur Radioastronomie, Bonn, Germany. We present the accurate modelling of one methanol maser in which many methanol masers have been detected and mark different objects (see Poster by V. Minier et al

  9. A near-infrared interferometric survey of debris disc stars. II. CHARA/FLUOR observations of six early-type dwarfs

    E-Print Network [OSTI]

    Absil, O; Merand, A; Augereau, J -C; Foresto, V Coude du; Defrere, D; Kervella, P; Aufdenberg, J P; Desort, M; Ehrenreich, D; Lagrange, A -M; Montagnier, G; Olofsson, J; Brummelaar, T A ten; McAlister, H A; Sturmann, J; Sturmann, L; Turner, N H

    2008-01-01T23:59:59.000Z

    High-precision interferometric observations of six early-type main sequence stars known to harbour cold debris discs have been obtained in the near-infrared K band with the FLUOR instrument at the CHARA Array. The measured squared visibilities are compared to the expected visibility of the stellar photospheres based on theoretical photospheric models taking into account rotational distortion, searching for potential visibility reduction at short baselines due to circumstellar emission. Our observations bring to light the presence of resolved circumstellar emission around one of the six target stars (zeta Aql) at the 5 sigma level. The morphology of the emission source cannot be directly constrained because of the sparse spatial frequency sampling of our interferometric data. Using complementary adaptive optics observations and radial velocity measurements, we find that the presence of a low-mass companion is a likely origin for the excess emission. The potential companion has a K-band contrast of four magnitu...

  10. 2014/2015 TA Training Program Page 1 of 4 Call for Proposals for 2014/2015 TA Training Programs

    E-Print Network [OSTI]

    Handy, Todd C.

    2014/2015 TA Training Program Page 1 of 4 Call for Proposals for 2014/2015 TA Training Programs, the University is committed to providing educational programs specifically addressing TAs needs. The TA Training for the development, delivery, and assessment of TA training programs. In so doing, we expect a significant increase

  11. Abstract--Many applications call for robots to perform tasks in workspaces where traditional vehicles cannot reach. Using

    E-Print Network [OSTI]

    Sitti, Metin

    1 Abstract-- Many applications call for robots to perform tasks in workspaces where traditional for wall climbing robots which can scale vertical walls. Many applications are of great interest robots for specific applications such as nuclear facilities inspection. In specific cases where

  12. Duval County Extension Service -March, 2012 Call 904-255-7450 to register or for more information

    E-Print Network [OSTI]

    Watson, Craig A.

    , Phillips Garden Store, Plant Ranch Spending and Saving Plans, 10 am ­ 1 pm Fresh Start Accounts, 10 am ­ 4 pm War on Poverty in Gateway Mall, Call to register March 20 On My Own financial simulation for teens, Rockaway Garden Center, Turner Ace Stores on Atlantic Blvd & on Marsh Landing Parkway Florida Saves

  13. NLP-based scripting for CALL activities Antoniadis G., Echinard S., Kraif O., Lebarb T., Loiseau M., Ponton C.

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    computing skills, didactic activities that could be recorded in more complex sequences or scenarios. 1 CALL: Conjugating NLP and language didactics It is generally reckoned that computer science can prove itself to be a great aid in language learning, when in fact, most often computer scientists and didactics experts do

  14. Open Call for Participation of PhD students International PhD course on Economic Geography

    E-Print Network [OSTI]

    Balland, Pierre-Alexandre

    Open Call for Participation of PhD students International PhD course on Economic Geography Main perspectives and approaches in economic geography. The core questions of this discipline ­ related to the role of place and space in processes of economic development ­ have in recent years attracted interest not just

  15. Plasma Basics Plasma is often called the "Fourth State of Matter". Although found in virtually every home and business,

    E-Print Network [OSTI]

    Plasma Basics Plasma is often called the "Fourth State of Matter". Although found in virtually every home and business, gas plasma is not well known. In fact, plasma is quite common - it is estimated that 99% of the visible universe consists of plasma. Earthbound plasmas include lightning, fluorescent

  16. HPI Future SOC Lab: Call for Projects The Hasso-Plattner-Institute (HPI) operates the "HPI Future SOC Lab" together

    E-Print Network [OSTI]

    Weske, Mathias

    by a number of smaller Intel systems as well as an NVIDIA Tesla GPU Computing system. SAP provides accessHPI Future SOC Lab: Call for Projects The Hasso-Plattner-Institute (HPI) operates the "HPI Future SOC Lab" together with its industrial partners EMC², Fujitsu, Hewlett-Packard, and SAP. EMC², Fujitsu

  17. HPI Future SOC Lab: Call for Projects The Hasso-Plattner-Institute (HPI) operates the "HPI Future SOC Lab" together

    E-Print Network [OSTI]

    Baer, Christian

    as an NVIDIA Tesla GPU Computing system. SAP provides access to its Platform as a Service offering, SAPHPI Future SOC Lab: Call for Projects The Hasso-Plattner-Institute (HPI) operates the "HPI Future SOC Lab" together with its industrial partners EMC², Fujitsu, Hewlett-Packard, and SAP. EMC², Fujitsu

  18. Summary -Procedure For Shutting Off The Oxygen Zone Valve 1. Implement RACE Call the Emergency Operator at 4-2012.

    E-Print Network [OSTI]

    Acton, Scott

    Summary - Procedure For Shutting Off The Oxygen Zone Valve 1. Implement RACE ­ Call the Emergency-cylinders for low oxygen needs and bag ventilated patients using E-cylinders. 4. Identify oxygen zone valve for the affected rooms/areas. 5. Turn off the flow of oxygen at the zone valve if the oxygen cannot be turned off

  19. IEEE Wireless Communications December 201366 1536-1284/13/$25.00 2013 IEEE ACCEPTED FROM OPEN CALL

    E-Print Network [OSTI]

    Zhang, Yan

    power grid into the future "Internet of energy." The conventional centrally controlled electrical grid power line and one wireless communication link. The LAG is part of the electricity distribution infra CALL INTRODUCTION The smart grid is the next-generation power grid that will transform the traditional

  20. How are the Books & Journals Arranged on the Shelves in the General Library? Understanding the Call Numbers

    E-Print Network [OSTI]

    Pasternack, Gregory B.

    number A-Z, using the Library of Congress Classification System. It is as an alphanumeric system is read as a decimal. e.g. E795 comes before E8 Library of Congress Classification System: A - Z A GeneralHow are the Books & Journals Arranged on the Shelves in the General Library? Understanding the Call