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Sample records for hfir core mass

  1. Preliminary Assessment of the Impact on Reactor Vessel dpa Rates Due to Installation of a Proposed Low Enriched Uranium (LEU) Core in the High Flux Isotope Reactor (HFIR)

    Energy Technology Data Exchange (ETDEWEB)

    Daily, Charles R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-10-01

    An assessment of the impact on the High Flux Isotope Reactor (HFIR) reactor vessel (RV) displacements-per-atom (dpa) rates due to operations with the proposed low enriched uranium (LEU) core described by Ilas and Primm has been performed and is presented herein. The analyses documented herein support the conclusion that conversion of HFIR to low-enriched uranium (LEU) core operations using the LEU core design of Ilas and Primm will have no negative impact on HFIR RV dpa rates. Since its inception, HFIR has been operated with highly enriched uranium (HEU) cores. As part of an effort sponsored by the National Nuclear Security Administration (NNSA), conversion to LEU cores is being considered for future HFIR operations. The HFIR LEU configurations analyzed are consistent with the LEU core models used by Ilas and Primm and the HEU balance-of-plant models used by Risner and Blakeman in the latest analyses performed to support the HFIR materials surveillance program. The Risner and Blakeman analyses, as well as the studies documented herein, are the first to apply the hybrid transport methods available in the Automated Variance reduction Generator (ADVANTG) code to HFIR RV dpa rate calculations. These calculations have been performed on the Oak Ridge National Laboratory (ORNL) Institutional Cluster (OIC) with version 1.60 of the Monte Carlo N-Particle 5 (MCNP5) computer code.

  2. High Flux Isotope Reactor (HFIR)

    Data.gov (United States)

    Federal Laboratory Consortium — The HFIR at Oak Ridge National Laboratory is a light-water cooled and moderated reactor that is the United States’ highest flux reactor-based neutron source. HFIR...

  3. Maximum stellar iron core mass

    Indian Academy of Sciences (India)

    F W Giacobbe

    2003-03-01

    An analytical method of estimating the mass of a stellar iron core, just prior to core collapse, is described in this paper. The method employed depends, in part, upon an estimate of the true relativistic mass increase experienced by electrons within a highly compressed iron core, just prior to core collapse, and is significantly different from a more typical Chandrasekhar mass limit approach. This technique produced a maximum stellar iron core mass value of 2.69 × 1030 kg (1.35 solar masses). This mass value is very near to the typical mass values found for neutron stars in a recent survey of actual neutron star masses. Although slightly lower and higher neutron star masses may also be found, lower mass neutron stars are believed to be formed as a result of enhanced iron core compression due to the weight of non-ferrous matter overlying the iron cores within large stars. And, higher mass neutron stars are likely to be formed as a result of fallback or accretion of additional matter after an initial collapse event involving an iron core having a mass no greater than 2.69 × 1030 kg.

  4. HFIR spent fuel management alternatives

    Energy Technology Data Exchange (ETDEWEB)

    Begovich, J.M.; Green, V.M.; Shappert, L.B.; Lotts, A.L.

    1992-10-15

    The High Flux Isotope Reactor (HFIR) at Martin Marietta Energy Systems' Oak Ridge National Laboratory (ORNL) has been unable to ship its spent fuel to Savannah River Site (SRS) for reprocessing since 1985. The HFIR storage pools are expected to fill up in the February 1994 to February 1995 time frame. If a management altemative to existing HFIR pool storage is not identified and implemented before the HFIR pools are full, the HFIR will be forced to shut down. This study investigated several alternatives for managing the HFIR spent fuel, attempting to identify options that could be implemented before the HFIR pools are full. The options investigated were: installing a dedicated dry cask storage facility at ORNL, increasing HFIR pool storage capacity by clearing the HFIR pools of debris and either close-packing or stacking the spent fuel elements, storing the spent fuel at another ORNL pool, storing the spent fuel in one or more hot cells at ORNL, and shipping the spent fuel offsite for reprocessing or storage elsewhere.

  5. Key metrics for HFIR HEU and LEU models

    Energy Technology Data Exchange (ETDEWEB)

    Ilas, Germina [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Betzler, Benjamin R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Chandler, David [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Renfro, David G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Davidson, Eva E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-10-25

    This report compares key metrics for two fuel design models of the High Flux Isotope Reactor (HFIR). The first model represents the highly enriched uranium (HEU) fuel currently in use at HFIR, and the second model considers a low-enriched uranium (LEU) interim design fuel. Except for the fuel region, the two models are consistent, and both include an experiment loading that is representative of HFIR's current operation. The considered key metrics are the neutron flux at the cold source moderator vessel, the mass of 252Cf produced in the flux trap target region as function of cycle time, the fast neutron flux at locations of interest for material irradiation experiments, and the reactor cycle length. These key metrics are a small subset of the overall HFIR performance and safety metrics. They were defined as a means of capturing data essential for HFIR's primary missions, for use in optimization studies assessing the impact of HFIR's conversion from HEU fuel to different types of LEU fuel designs.

  6. Evaluation of HFIR LEU Fuel Using the COMSOL Multiphysics Platform

    Energy Technology Data Exchange (ETDEWEB)

    Primm, Trent [ORNL; Ruggles, Arthur [ORNL; Freels, James D [ORNL

    2009-03-01

    A finite element computational approach to simulation of the High Flux Isotope Reactor (HFIR) Core Thermal-Fluid behavior is developed. These models were developed to facilitate design of a low enriched core for the HFIR, which will have different axial and radial flux profiles from the current HEU core and thus will require fuel and poison load optimization. This report outlines a stepwise implementation of this modeling approach using the commercial finite element code, COMSOL, with initial assessment of fuel, poison and clad conduction modeling capability, followed by assessment of mating of the fuel conduction models to a one dimensional fluid model typical of legacy simulation techniques for the HFIR core. The model is then extended to fully couple 2-dimensional conduction in the fuel to a 2-dimensional thermo-fluid model of the coolant for a HFIR core cooling sub-channel with additional assessment of simulation outcomes. Finally, 3-dimensional simulations of a fuel plate and cooling channel are presented.

  7. NICHD Biomedical Mass Spectrometry Core Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The NICHD Biomedical Mass Spectrometry Core Facility was created under the auspices of the Office of the Scientific Director to provide high-end mass-spectrometric...

  8. Conceptual Design Parameters for HFIR LEU U-Mo Fuel Conversion Experimental Irradiations

    Energy Technology Data Exchange (ETDEWEB)

    Renfro, David G [ORNL; Cook, David Howard [ORNL; Chandler, David [ORNL; Ilas, Germina [ORNL; Jain, Prashant K [ORNL

    2013-03-01

    The High Flux Isotope Reactor (HFIR) is a versatile research reactor that is operated at the Oak Ridge National Laboratory (ORNL). The HFIR core is loaded with high-enriched uranium (HEU) and operates at a power level of 85 MW. The primary scientific missions of the HFIR include cold and thermal neutron scattering, materials irradiation, and isotope production. An engineering design study of the conversion of the HFIR from HEU to low-enriched uranium (LEU) fuel is ongoing at the Oak Ridge National Laboratory. The LEU fuel considered is based on a uranium-molybdenum alloy that is 10 percent by weight molybdenum (U-10Mo) with a 235U enrichment of 19.75 wt %. The LEU core design discussed in this report is based on the design documented in ORNL/TM-2010/318. Much of the data reported in Sections 1 and 2 of this document was derived from or taken directly out of ORNL/TM-2010/318. The purpose of this report is to document the design parameters for and the anticipated normal operating conditions of the conceptual HFIR LEU fuel to aid in developing requirements for HFIR irradiation experiments.

  9. Limits on the Core Mass of Jupiter

    Science.gov (United States)

    Stevenson, D. J.

    2015-12-01

    The core is here defined as the central concentration of elements heavier than hydrogen and helium (it need not be solid and it need not be purely heavy elements and it will not have a sharp boundary). Its determination is a major goal of the Juno mission (2016-17) and it will be difficult to determine because it is expected to be only a few percent of the total mass. It has long been known that there is no prospect of determining the nature of this core (e.g., its density) from gravity measurements, even though the mass can be estimated. By consideration of simple models that are nonetheless faithful to the essential physics, it is further shown that should the core be contaminated with light elements (hydrogen and helium) then the gravity data can tell us the core mass as defined (with some caveats about the fuzziness of its boundary) but not the total mass within some small radius (which could include any light elements mixed in). This is both good and bad news: Good in that the core is thought to be diagnostic of the conditions under which the planet formed but bad in that the admixture also tells us more about both formation process and core erosion. Further, a linear perturbation theory has been developed that provides an easy approximate way of determining how errors in the equation of state (EOS) propagate into errors in the estimated core mass or envelope enrichment in heavies in models that nonetheless satisfy all observables. This theory does not require detailed models of the planet but provides an integral mapping from changes in the EOS into approximate changes in radius at fixed mass, and low degree gravity (or moment of inertia, MOI). This procedure also shows that there exist perturbations that leave the radius, mass and MOI unchanged but cause a change in J2, though in practice the non-uniqueness of structure by this consideration (~0.2% or less in MOI for example) is less than the non-uniqueness arising from likely EOS uncertainties (~1% in total

  10. Mass Distribution in Galaxy Cluster Cores

    CERN Document Server

    Hogan, M T; Pulido, F; Nulsen, P E J; Russell, H R; Vantyghem, A N; Edge, A C; Main, R A

    2016-01-01

    Many processes within galaxy clusters, such as those believed to govern the onset of thermally unstable cooling and AGN feedback, are dependent upon local dynamical timescales. However, accurately mapping the mass distribution within individual clusters is challenging, particularly towards cluster centres where the total mass budget has substantial radially-dependent contributions from the stellar, gas, and dark matter components. In this paper we use a small sample of galaxy clusters with deep Chandra observations and good ancillary tracers of their gravitating mass at both large and small radii to develop a method for determining mass profiles that span a wide radial range and extend down into the central galaxy. We also consider potential observational pitfalls in understanding cooling in hot cluster atmospheres, and find tentative evidence for a relationship between the radial extent of cooling X-ray gas and nebular H-alpha emission in cool core clusters. Amongst this small sample we find no support for t...

  11. Impact of HFIR LEU Conversion on Beryllium Reflector Degradation Factors

    Energy Technology Data Exchange (ETDEWEB)

    Ilas, Dan [ORNL

    2013-10-01

    An assessment of the impact of low enriched uranium (LEU) conversion on the factors that may cause the degradation of the beryllium reflector is performed for the High Flux Isotope Reactor (HFIR). The computational methods, models, and tools, comparisons with previous work, along with the results obtained are documented and discussed in this report. The report documents the results for the gas and neutronic poison production, and the heating in the beryllium reflector for both the highly enriched uranium (HEU) and LEU HFIR configurations, and discusses the impact that the conversion to LEU may have on these quantities. A time-averaging procedure was developed to calculate the isotopic (gas and poisons) production in reflector. The sensitivity of this approach to different approximations is gauged and documented. The results show that the gas is produced in the beryllium reflector at a total rate of 0.304 g/cycle for the HEU configuration; this rate increases by ~12% for the LEU case. The total tritium production rate in reflector is 0.098 g/cycle for the HEU core and approximately 11% higher for the LEU core. A significant increase (up to ~25%) in the neutronic poisons production in the reflector during the operation cycles is observed for the LEU core, compared to the HEU case, for regions close to the core s horizontal midplane. The poisoning level of the reflector may increase by more than two orders of magnitude during long periods of downtime. The heating rate in the reflector is estimated to be approximately 20% lower for the LEU core than for the HEU core. The decrease is due to a significantly lower contribution of the heating produced by the gamma radiation for the LEU core. Both the isotopic (gas and neutronic poisons) production and the heating rates are spatially non-uniform throughout the beryllium reflector volume. The maximum values typically occur in the removable reflector and close to the midplane.

  12. Mass Distribution in Galaxy Cluster Cores

    Science.gov (United States)

    Hogan, M. T.; McNamara, B. R.; Pulido, F.; Nulsen, P. E. J.; Russell, H. R.; Vantyghem, A. N.; Edge, A. C.; Main, R. A.

    2017-03-01

    Many processes within galaxy clusters, such as those believed to govern the onset of thermally unstable cooling and active galactic nucleus feedback, are dependent upon local dynamical timescales. However, accurate mapping of the mass distribution within individual clusters is challenging, particularly toward cluster centers where the total mass budget has substantial radially dependent contributions from the stellar (M *), gas (M gas), and dark matter (M DM) components. In this paper we use a small sample of galaxy clusters with deep Chandra observations and good ancillary tracers of their gravitating mass at both large and small radii to develop a method for determining mass profiles that span a wide radial range and extend down into the central galaxy. We also consider potential observational pitfalls in understanding cooling in hot cluster atmospheres, and find tentative evidence for a relationship between the radial extent of cooling X-ray gas and nebular Hα emission in cool-core clusters. At large radii the entropy profiles of our clusters agree with the baseline power law of K ∝ r 1.1 expected from gravity alone. At smaller radii our entropy profiles become shallower but continue with a power law of the form K ∝ r 0.67 down to our resolution limit. Among this small sample of cool-core clusters we therefore find no support for the existence of a central flat “entropy floor.”

  13. Discerning the Form of the Dense Core Mass Function

    CERN Document Server

    Swift, Jonathan J

    2009-01-01

    We investigate the ability to discern between lognormal and powerlaw forms for the observed mass function of dense cores in star forming regions. After testing our fitting, goodness-of-fit, and model selection procedures on simulated data, we apply our analysis to 14 datasets from the literature. Whether the core mass function has a powerlaw tail or whether it follows a pure lognormal form cannot be distinguished from current data. From our simulations it is estimated that datasets from uniform surveys containing more than approximately 500 cores with a completeness limit below the peak of the mass distribution are needed to definitively discern between these two functional forms. We also conclude that the width of the core mass function may be more reliably estimated than the powerlaw index of the high mass tail and that the width may also be a more useful parameter in comparing with the stellar initial mass function to deduce the statistical evolution of dense cores into stars.

  14. The evolution of the core mass function by gas accretion

    CERN Document Server

    Dib, Sami

    2012-01-01

    We show how the mass function of dense cores (CMF) which results from the gravoturbulent fragmentation of a molecular cloud evolves in time under the effect of gas accretion. Accretion onto the cores leads to the formation of larger numbers of massive cores and to a flattening of the CMF. This effect should be visible in the CMF of star forming regions that are massive enough to contain high mass cores and when comparing the CMF of cores in and off dense filaments which have different environmental gas densities.

  15. A Massive, Prestellar Clump Hosting no High-Mass Cores

    Science.gov (United States)

    Sanhueza, P.; Jackson, J. M.; Zhang, Q.; Foster, J.; Guzmán, A.

    2015-12-01

    We observed a high-mass, prestellar clump in dust continuum with SMA (3.5″) and in NH3 line emission with JVLA (2″). We find no core with sufficient mass to form high-mass stars at the current evolutionary stage. In order to form high-mass stars, the embedded cores need to accrete a significant amount of mass over time which is consistent with some models of high-mass star formation. We also find that the gas in the cores is transonic or mildly supersonic. The embedded cores are sub-virialized, which is inconsistent with some models of high-mass star formation unless strong magnetic fields of ˜1 mG are present.

  16. On the Evolution of the Dense Core Mass Function

    CERN Document Server

    Williams, Jonathan J Swift Jonathan P

    2008-01-01

    The mass distributions of dense cores in star-forming regions are measured to have a shape similar to the initial mass function of stars. This has been generally interpreted to mean that the constituent cores will form individual stars or stellar systems at a nearly constant star formation efficiency. This article presents a series of numerical experiments evolving distributions of dense cores into stars to quantify the effects of stellar multiplicity, global core fragmentation, and a varying star formation efficiency. We find that the different evolutionary schemes have an overall small effect on the shape of the resultant distribution of stars. Our results imply that at the current level of observational accuracy the comparison between the mass functions of dense cores and stars alone is insufficient to discern between different evolutionary models. Observations over a wide range of mass scales including the high or low-mass tails of these distributions have the largest potential for discerning between diff...

  17. Origin of the dense core mass function in contracting filaments

    CERN Document Server

    Myers, Philip C

    2013-01-01

    Mass functions of starless dense cores (CMFs) may arise from contraction and dispersal of core-forming filaments. In an illustrative model, a filament contracts radially by self-gravity, increasing the mass of its cores. During this contraction, FUV photoevaporation and ablation by shocks and winds disperse filament gas and limit core growth. The stopping times of core growth are described by a waiting-time distribution. The initial filament column density profile and the resulting CMF each match recent Herschel observations in detail. Then low-mass cores have short growth ages and arise from the innermost filament gas, while massive cores have long growth ages and draw from more extended filament gas. The model fits the initial density profile and CMF best for mean core density 2 10^4 cm^-3 and filament dispersal time scale 0.5 Myr. Then the typical core mass, radius, mean column density, and contraction speed are respectively 0.8 solar masses, 0.06 pc, 6 10^21 cm^-2, and 0.07 km s^-1, also in accord with ob...

  18. Do protostellar fountains shape the regional core mass function?

    Institute of Scientific and Technical Information of China (English)

    Jin-Zeng Li; Claudio Carlos Mallamaci; Ricardo César Podestá; Eloy Actis Vicente; Ya-Fang Huang; Ana Maria Pacheco

    2013-01-01

    The emerging massive binary system associated with AFGL 961 signifies the latest generation of massive star and cluster formation in the Rosette Molecular Complex.We present the detection of a compact cluster of dusty cores toward the AFGL 961 region based on continuum imaging at 1.3 mm by the Submillimeter Array.The binary components of AFGL 961 are associated with the most intensive millimeter emission cores or envelopes,confirming that they are indeed in an early stage of evolution.The other massive cores,however,are found to congregate in the close vicinity of the central high-mass protostellar binary.They have no apparent infrared counterparts and are,in particular,well aligned transverse to the bipolar molecular outflows originating from AFGL 961.This provides evidence for a likely triggered origin of the massive cores.All 40 individual cores with masses ranging between 0.6 and 15 M⊙ were detected above a 3 σ level of 3.6 mJy beam-1 (or 0.4 M⊙),based on which we derive a total core mass of 107 M⊙ in the AFGL 961 region.As compared to the stellar initial mass function,a shallow slope of 1.8 is,however,derived from the best fit to the mass spectrum of the millimeter cores with a prestellar and/or protostellar origin.The flatter core mass distribution in the AFGL 961 region is attributed here to dynamic perturbations from the massive molecular outflows that originated from the massive protostellar binary,which may have altered the otherwise more quiescent conditions of core or star formation,enhanced the formation of more massive cores and,as a result,influenced the core mass distribution in its close vicinity.

  19. Small Specimen Data from a High Temperature HFIR Irradiation Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Burchell, Timothy D [ORNL; McDuffee, Joel Lee [ORNL; Thoms, Kenneth R [ORNL

    2014-01-01

    The HTV capsule is a High Flux Isotope Reactor (HFIR) target-rod capsule designed to operate at very high temperatures. The graphite containing section of the capsule (in core) is approximately 18 inches (457.2 mm) long and is separated into eight temperature zones. The specimen diameters within each zone are set to achieve the desired gas gap and hence design temperature (900 C, 1200 C or 1500 C). The capsule has five zones containing 0.400 inch (10.16 mm) diameter specimens, two zones containing 0.350 inch (8.89 mm) diameter specimens and one zone containing 0.300 inch (7.62 mm) diameter specimens. The zones have been distributed within the experiment to optimize the gamma heating from the HFIR core as well as minimize the axial heat flow in the capsule. Consequently, there are two 900 C zones, three 1200 C zones, and three 1500 C zones within the HTV capsule. Each zone contains nine specimens 0.210 0.002 inches (5.334 mm) in length. The capsule will be irradiated to a peak dose of 3.17 displacements per atom. The HTV specimens include samples of the following graphite grades: SGL Carbon s NBG-17 and NBG-18, GrafTech s PCEA, Toyo Tanso s IG-110, Mersen s 2114 and the reference grade H-451 (SGL Carbon). As part of the pre-irradiation program the specimens were characterized using ASTM Standards C559 for bulk density, and ASTM C769 for approximate Young s modulus from the sonic velocity. The probe frequency used for the determination of time of flight of the ultrasonic signal was 2.25 MHz. Marked volume (specimen diameter) effects were noted for both bulk density (increased with increasing specimen volume or diameter) and Dynamic Young s modulus (decreased with increasing specimen volume or diameter). These trends are extended by adding the property vs. diameter data for unirradiated AGC-1 creep specimens (nominally 12.5 mm-diameter x 25.4 mm-length). The relatively large reduction in Dynamic Young s Modulus was surprising given the trend for increasing density

  20. Rotating neutron stars with exotic cores: masses, radii, stability

    Energy Technology Data Exchange (ETDEWEB)

    Haensel, P.; Bejger, M.; Fortin, M.; Zdunik, L. [Polish Academy of Sciences, N. Copernicus Astronomical Center, Warszawa (Poland)

    2016-03-15

    A set of theoretical mass-radius relations for rigidly rotating neutron stars with exotic cores, obtained in various theories of dense matter, is reviewed. Two basic observational constraints are used: the largest measured rotation frequency (716Hz) and the maximum measured mass (2M {sub CircleDot}). The present status of measuring the radii of neutron stars is described. The theory of rigidly rotating stars in general relativity is reviewed and limitations of the slow rotation approximation are pointed out. Mass-radius relations for rotating neutron stars with hyperon and quark cores are illustrated using several models. Problems related to the non-uniqueness of the crust-core matching are mentioned. Limits on rigid rotation resulting from the mass-shedding instability and the instability with respect to the axisymmetric perturbations are summarized. The problem of instabilities and of the back-bending phenomenon are discussed in detail. Metastability and instability of a neutron star core in the case of a first-order phase transition, both between pure phases, and into a mixed-phase state, are reviewed. The case of two disjoint families (branches) of rotating neutron stars is discussed and generic features of neutron-star families and of core-quakes triggered by the instabilities are considered. (orig.)

  1. Rotating neutron stars with exotic cores: masses, radii, stability

    CERN Document Server

    Haensel, P; Fortin, M; Zdunik, J L

    2016-01-01

    A set of theoretical mass-radius relations for rigidly rotating neutron stars with exotic cores, obtained in various theories of dense matter, is reviewed. Two basic observational constraints are used: the largest measured rotation frequency is 716 Hz and the maximum measured mass is $2\\;{\\rm M}_\\odot$. Present status of measuring the radii of neutron stars is described. The theory of rigidly rotating stars in general relativity is reviewed and limitations of the slow rotation approximation are pointed out. Mass-radius relations for rotating neutron stars with hyperon and quark cores are illustrated using several models. Problems related to the non-uniqueness of the crust-core matching are mentioned. Limits on rigid rotation resulting from the mass-shedding instability and the instability with respect to the axisymmetric perturbations are summarized. The problem of instabilities and of the back-bending phenomenon are discussed in detail. Metastability and instability of a neutron star core in the case of a fi...

  2. Neutron Dosimetry of the HFIR Hydraulic Facility

    CERN Document Server

    Mahmood, S T

    1995-01-01

    The total, fast, and thermal neutron fluxes at five axial positions in the High Flux Isotope Reactor (HFIR) hydraulic tube have been measured using bare and/or cadmium-covered activation, fission, and helium accumulation flux monitors. The spectrum-averaged, one-group cross sections over selected energy ranges for the reactions used in the measurements were obtained using cross sections from the ENDF/B-V file, and the target region volume-integrated spectrum was calculated with DORT, a two-dimensional discrete ordinates radiation transport code. The fluxes obtained from various monitors are in good agreement. The total and fast (>1 MeV) neutron fluxes vary from 1.6 x 10 sup 1 sup 9 n/m sup 2 centre dot s and 1.6 x 10 sup 1 sup 8 n/m sup 2 centre dot s, respectively, at the ends (HT-1 and -9) of the facility to 4.0 x 10 sup 1 sup 9 n/m sup 2 centre dot s and 4.6 x 10 sup 1 sup 8 n/m sup 2 centre dot s, respectively, at the center (HT-5) of the facility. The thermal-to-fast (> 1 MeV) flux ratio varies from abou...

  3. The dependence of convective core overshooting on stellar mass

    CERN Document Server

    Claret, Antonio

    2016-01-01

    Convective core overshooting extends the main-sequence lifetime of a star. Evolutionary tracks computed with overshooting are quite different from those that use the classical Schwarzschild criterion, which leads to rather different predictions for the stellar properties. Attempts over the last two decades to calibrate the degree of overshooting with stellar mass using detached double-lined eclipsing binaries have been largely inconclusive, mainly due to a lack of suitable observational data. Here we revisit the question of a possible mass dependence of overshooting with a more complete sample of binaries, and examine any additional relation there might be with evolutionary state or metal abundance Z. We use a carefully selected sample of 33 double-lined eclipsing binaries strategically positioned in the H-R diagram, with accurate absolute dimensions and component masses ranging from 1.2 to 4.4 solar masses. We compare their measured properties with stellar evolution calculations to infer semi-empirical value...

  4. Model uniform core criteria for mass casualty triage.

    Science.gov (United States)

    2011-06-01

    There is a need for model uniform core criteria for mass casualty triage because disasters frequently cross jurisdictional lines and involve responders from multiple agencies who may be using different triage tools. These criteria (Tables 1-4) reflect the available science, but it is acknowledged that there are significant research gaps. When no science was available, decisions were formed by expert consensus derived from the available triage systems. The intent is to ensure that providers at a mass-casualty incident use triage methodologies that incorporate these core principles in an effort to promote interoperability and standardization. At a minimum, each triage system must incorporate the criteria that are listed below. Mass casualty triage systems in use can be modified using these criteria to ensure interoperability. The criteria include general considerations, global sorting, lifesaving interventions, and assignment of triage categories. The criteria apply only to providers who are organizing multiple victims in a discrete geographic location or locations, regardless of the size of the incident. They are classified by whether they were derived through available direct scientific evidence, indirect scientific evidence, expert consensus, and/or are used in multiple existing triage systems. These criteria address only primary triage and do not consider secondary triage. For the purposes of this document the term triage refers to mass-casualty triage and provider refers to any person who assigns primary triage categories to victims of a mass-casualty incident.

  5. Hot-Jupiter Core Mass from Roche-lobe Overflow

    CERN Document Server

    Ginzburg, Sivan

    2016-01-01

    The orbits of many observed hot Jupiters are decaying rapidly due to tidal interaction, eventually reaching the Roche limit. We analytically study the ensuing coupled mass loss and orbital evolution during the Roche-lobe overflow and find two possible scenarios. Planets with light cores $M_c\\lesssim 6M_\\oplus$ (assuming a nominal tidal dissipation factor $Q\\sim 10^6$ for the host star) are transformed into Neptune-mass gas planets, orbiting at a separation (relative to the stellar radius) $a/R_\\star\\approx 3.5$. Planets with heavier cores $M_c\\gtrsim 6M_\\oplus$ plunge rapidly until they are destroyed at the stellar surface. Remnant gas-Neptunes, which are stable to photo-evaporation, are absent from the observations, despite their unique transit radius ($5-10R_\\oplus$). This result suggests that $M_c\\gtrsim 6M_\\oplus$, providing a useful constraint on the poorly-known core mass that may distinguish between different formation theories of gas giants. Alternatively, given a prior estimate of $M_c\\approx 6 M_\\op...

  6. Dynamical Models to Infer the Core Mass Fraction of Venus

    Science.gov (United States)

    Quintana, Elisa V.; Barclay, Thomas

    2016-10-01

    The uncompressed density of Venus is just a few percent lower than Earth's, however the nature of the interior core structure of Venus remains unclear. Employing state-of-the-art dynamical formation models that allow both accretion and collisional fragmentation, we perform hundreds of simulations of terrestrial planet growth around the Sun in the presence of the giant planets. For both Earth and Venus analogs, we quantify the iron-silicate ratios, water/volatile abundances and specific impact energies of all collisions that lead to their formation. Preliminary results suggest that the distributions of core mass fraction and water content are comparable among the Earth and Venus analogs, suggesting that Earth and Venus may indeed have formed with similar structures and compositions.

  7. A SCUBA survey of Orion, the low-mass end of the core mass function

    CERN Document Server

    Nutter, D

    2006-01-01

    We have re-analysed all of the SCUBA archive data of the Orion star-forming regions. We have put together all of the data taken at different times by different groups. Consequently we have constructed the deepest submillimetre maps of these regions ever made. There are four regions that have been mapped: Orion A North & South, and Orion B North & South. We find that two of the regions, Orion A North and Orion B North, have deeper sensitivity and completeness limits, and contain a larger number of sources, so we concentrate on these two. We compare the data with archive data from the Spitzer Space Telescope to determine whether or not a core detected in the submillimetre is pre-stellar in nature. We extract all of the pre-stellar cores from the data and make a histogram of the core masses. This can be compared to the stellar initial mass function (IMF). We find the high-mass core mass function follows a roughly Salpeter-like slope, just like the IMF, as seen in previous work. Our deeper maps allow us t...

  8. The relationship between the prestellar core mass function and the stellar initial mass function

    CERN Document Server

    Goodwin, Simon P; Kroupa, Pavel; Ward-Thompson, Derek; Whitworth, Anthony P

    2007-01-01

    Stars form from dense molecular cores, and the mass function of these cores (the CMF) is often found to be similar to the form of the stellar initial mass function (IMF). This suggests that the form of the IMF is the result of the form of the CMF. However, most stars are thought to form in binary and multiple systems, therefore the relationship between the IMF and the CMF cannot be trivial. We test two star formation scenarios - one in which all stars form as binary or triple systems, and one in which low-mass stars form in a predominantly single mode. We show that from a log-normal CMF, similar to those observed, and expected on theoretical grounds, the model in which all stars form as multiples gives a better fit to the IMF.

  9. The core-halo mass relation of ultra-light axion dark matter from merger history

    CERN Document Server

    Du, Xiaolong; Niemeyer, Jens C; Schwabe, Bodo

    2016-01-01

    In the context of structure formation with ultra-light axion dark matter, we offer an alternative explanation for the mass relation of solitonic cores and their host halos observed in numerical simulations. Our argument is based entirely on the mass gain that occurs during major mergers of binary cores and largely independent of the initial core-halo mass relation assigned to hosts that have just collapsed. We find a relation between the halo mass $M_h$ and corresponding core mass $M_c$, $M_c\\propto M_h^{2\\beta-1}$, where $(1-\\beta)$ is the core mass loss fraction. Following the evolution of core masses in stochastic merger trees, we find empirical evidence for our model. Our results are useful for statistically modeling the effects of dark matter cores on the properties of galaxies and their substructures in axion dark matter cosmologies.

  10. Meeting notes of the High Flux Isotope Reactor (HFIR) futures group

    Energy Technology Data Exchange (ETDEWEB)

    Houser, M.M. [comp.

    1995-08-01

    This report is a compilation of the notes from the ten meetings. The group charter is: (1) to identify and characterize the range of possibilities and necessities for keeping the HFIR operating for at least the next 15 years; (2) to identify and characterize the range of possibilities for enhancing the scientific and technical utility of the HFIR; (3) to evaluate the benefits or impacts of these possibilities on the various scientific fields that use the HFIR or its products; (4) to evaluate the benefits or impacts on the operation and maintenance of the HFIR facility and the regulatory requirements; (5) to estimate the costs, including operating costs, and the schedules, including downtime, for these various possibilities; and one possible impact of proposed changes may be to stimulate increased pressure for a reduced enrichment fuel for HFIR.

  11. Accuracy of core mass estimates in simulated observations of dust emission

    CERN Document Server

    Malinen, J; Collins, D C; Lunttila, T; Padoan, P

    2010-01-01

    We study the use of sub-millimetre dust emission in the estimation of the masses of molecular cloud cores. We want to determine the reliability of the mass estimates and at what level the observational biases are visible in the derived clump mass spectra. We use magnetohydrodynamic simulations and radiative transfer calculations to produce synthetic observations of dust emission. The synthetic maps have a spatial resolution and noise levels typical of the current Herschel surveys. Based on these data we estimate the dust temperatures and the column densities and compare the 'observed' core masses to the true values. We study the effects of spatial variations of dust properties. With high resolution adaptive mesh refinement simulations we also investigate how protostellar sources embedded in the cores affect the mass estimates. The shape, although not the position, of the mass spectrum is very reliable against observational errors. However, the core masses will be strongly underestimated in cores that have opt...

  12. Measuring the extent of convective cores in low-mass stars using Kepler data: towards a calibration of core overshooting

    CERN Document Server

    Deheuvels, S; Aguirre, V Silva; Ballot, J; Michel, E; Cunha, M S; Lebreton, Y; Appourchaux, T

    2016-01-01

    Our poor understanding of the boundaries of convective cores generates large uncertainties on the extent of these cores and thus on stellar ages. Our aim is to use asteroseismology to consistently measure the extent of convective cores in a sample of main-sequence stars whose masses lie around the mass-limit for having a convective core. We first test and validate a seismic diagnostic that was proposed to probe in a model-dependent way the extent of convective cores using the so-called $r_{010}$ ratios, which are built with $l=0$ and $l=1$ modes. We apply this procedure to 24 low-mass stars chosen among Kepler targets to optimize the efficiency of this diagnostic. For this purpose, we compute grids of stellar models with both the CESAM2k and MESA evolution codes, where the extensions of convective cores are modeled either by an instantaneous mixing or as a diffusion process. Among the selected targets, we are able to unambiguously detect convective cores in eight stars and we obtain seismic measurements of th...

  13. THE STRUCTURE OF GAS-ACCRETING PROTOPLANETS AND THE CONDITION OF THE CRITICAL CORE MASS

    Energy Technology Data Exchange (ETDEWEB)

    Kanagawa, Kazuhiro D. [Department of Cosmosciences, Graduate School of Science, Hokkaido University, N10 W8, Sapporo 060-0810 (Japan); Fujimoto, Masayuki Y., E-mail: kanagawa@astro1.sci.hokudai.ac.jp [Nuclear Reaction Data Center, Graduate School of Science, Hokkaido University, Kita 10 Nishi 8, Kita-ku, Sapporo 060-0810 (Japan)

    2013-03-01

    In the core accretion model for the formation of gas giant planets, runaway gas accretion onto a core is the primary requisite, triggered when the core mass reaches a critical value. The recently revealed wide diversity of the extrasolar giant planets suggests the necessity to further the understanding of the conditions resulting in the critical core mass that initiates runaway accretion. We study the internal structure of protoplanets under hydrostatic and thermal equilibria represented in terms of a polytropic equation of state to investigate what factors determine and affect the critical core mass. We find that the protoplanets, embedded in protoplanetary disks, have the same configuration as red giants, characterized by the envelope of the centrally condensed type solution. Applying the theory of stellar structure with homology invariants, we demonstrate that there are three types of criteria for the critical core mass depending on the stiffness of polytrope and the nature of outer boundary condition. For the stiff polytropes of index N {<=} 3 with the Bondi radius as the outer boundary, the criterion governing the critical core mass occurs at the surface. For stiff polytropes with the Hill outer boundary and for soft polytropes of N > 3, this criterion acts at the bottom of gaseous envelope. Further, we elucidate the roles and effects of coexistent radiative and convective zones in the envelope of critical core mass. Based on the results, we discuss the relevance of Bondi and Hill surface conditions and explore the parameter dependences of critical core mass.

  14. Mass estimates for very cold (< 8 K) gas in molecular cloud cores

    CERN Document Server

    Steinacker, Juergen; Beuther, Henrik; Henning, Thomas; Bacmann, Aurore

    2016-01-01

    The mass of prestellar cores is an essential ingredient to understand the onset of star formation in the core. The low level of emission from cold dust may keep parts of it hidden from observation. We aim to determine the fraction of core mass in the temperature range < 8 K that can be expected for typical low- and high-mass star formation regions. We calculate the dust temperature within standard spherically symmetric prestellar cores for a grid of density powerlaws in the outer core regions, core masses, and variation in the external multi-component radiation field. The dust is assumed to be composed of amorphous silicate and carbon, and variations of its optical properties are discussed. As measure for the distribution of cores and clumps, we use core mass functions derived for various environments. In view of the high densities in very cold central regions, dust and gas temperatures are assumed to be equal. We find that the fraction of mass with temperatures < 8 K in typical low- and high-mass cores...

  15. Synthetic observations of first hydrostatic cores in collapsing low-mass dense cores. I. Spectral energy distributions and evolutionary sequence

    CERN Document Server

    Commercon, Benoit; Dullemond, Cornelis P; Henning, Thomas

    2012-01-01

    The low-mass star formation evolutionary sequence is relatively well-defined both from observations and theoretical considerations. The first hydrostatic core is the first protostellar equilibrium object that is formed during the star formation process. Using state-of-the-art radiation-magneto-hydrodynamic 3D adaptive mesh refinement calculations, we aim to provide predictions for the dust continuum emission from first hydrostatic cores. We investigate the collapse and the fragmentation of magnetized one solar mass prestellar dense cores and the formation and evolution of first hydrostatic cores using the RAMSES code. We use three different magnetization levels for the initial conditions, which cover a large variety of early evolutionary morphology, e.g., the formation of a disk or a pseudo-disk, outflow launching, and fragmentation. We post-process the dynamical calculations using the 3D radiative transfer code RADMC-3D. We compute spectral energy distributions and usual evolutionary stage indicators such as...

  16. On the fidelity of the core mass functions derived from dust column density data

    CERN Document Server

    Kainulainen, J; Rathborne, J M; Alves, J F

    2009-01-01

    Aims: We examine the recoverability and completeness limits of the dense core mass functions (CMFs) derived for a molecular cloud using extinction data and a core identification scheme based on two-dimensional thresholding. Methods: We performed simulations where a population of artificial cores was embedded into the variable background extinction field of the Pipe nebula. We extracted the cores from the simulated extinction maps, constructed the CMFs, and compared them to the input CMFs. The simulations were repeated using a variety of extraction parameters and several core populations with differing input mass functions and differing degrees of crowding. Results: The fidelity of the observed CMF depends on the parameters selected for the core extraction algorithm for our background. More importantly, it depends on how crowded the core population is. We find that the observed CMF recovers the true CMF reliably when the mean separation of cores is larger than their mean diameter (f>1). If this condition holds...

  17. Design and simulation of the CG1 beamline at HFIR

    Science.gov (United States)

    Nagler, S. E.; Lee, W.-T.; Moon, R. M.

    In the near future a super-critical hydrogen cold source will be installed in the HB4 beam tube of the High Flux Isotope Reactor (HFIR), Oak Ridge National Laboratory. The cold source will illuminate four neutron guides. Here we discuss the design and simulation of the guide CG1, dedicated to a new triple axis spectrometer. The conceptual design for the HFIR guides, including CG1, was aided by numerical calculations of neutron trajectories and acceptance diagrams. The CG1 guide consists of a partially trumpeting two-channel bender and a straight guide section. The design was subsequently modeled in detail from source to specimen, utilizing the McStas program. The lessons learned from the McStas simulations resulted in some minor but important changes in the design, and these were also verified using the original method of calculation. The resulting combination of guide and vertically focusing monochromator should deliver a beam with excellent spatial and angular distributions in and out of the scattering plane. The available intensity will enable the construction of a powerful spectrometer for incident energies as large as 20-25 meV.

  18. Design and simulation of the CG1 beamline at HFIR

    CERN Document Server

    Nagler, S E; Moon, R M

    2002-01-01

    In the near future a super-critical hydrogen cold source will be installed in the HB4 beam tube of the High Flux Isotope Reactor (HFIR), Oak Ridge National Laboratory. The cold source will illuminate four neutron guides. Here we discuss the design and simulation of the guide CG1, dedicated to a new triple axis spectrometer. The conceptual design for the HFIR guides, including CG1, was aided by numerical calculations of neutron trajectories and acceptance diagrams. The CG1 guide consists of a partially trumpeting two-channel bender and a straight guide section. The design was subsequently modeled in detail from source to specimen, utilizing the McStas program. The lessons learned from the McStas simulations resulted in some minor but important changes in the design, and these were also verified using the original method of calculation. The resulting combination of guide and vertically focusing monochromator should deliver a beam with excellent spatial and angular distributions in and out of the scattering plan...

  19. Analysis of dpa Rates in the HFIR Reactor Vessel using a Hybrid Monte Carlo/Deterministic Method*

    Directory of Open Access Journals (Sweden)

    Risner J.M.

    2016-01-01

    Full Text Available The Oak Ridge High Flux Isotope Reactor (HFIR, which began full-power operation in 1966, provides one of the highest steady-state neutron flux levels of any research reactor in the world. An ongoing vessel integrity analysis program to assess radiation-induced embrittlement of the HFIR reactor vessel requires the calculation of neutron and gamma displacements per atom (dpa, particularly at locations near the beam tube nozzles, where radiation streaming effects are most pronounced. In this study we apply the Forward-Weighted Consistent Adjoint Driven Importance Sampling (FW-CADIS technique in the ADVANTG code to develop variance reduction parameters for use in the MCNP radiation transport code. We initially evaluated dpa rates for dosimetry capsule locations, regions in the vicinity of the HB-2 beamline, and the vessel beltline region. We then extended the study to provide dpa rate maps using three-dimensional cylindrical mesh tallies that extend from approximately 12 in. below to approximately 12 in. above the height of the core. The mesh tally structures contain over 15,000 mesh cells, providing a detailed spatial map of neutron and photon dpa rates at all locations of interest. Relative errors in the mesh tally cells are typically less than 1%.

  20. Analysis of dpa rates in the HFIR reactor vessel using a hybrid Monte Carlo/deterministic method

    Energy Technology Data Exchange (ETDEWEB)

    Blakeman, Edward [Retired

    2016-01-01

    The Oak Ridge High Flux Isotope Reactor (HFIR), which began full-power operation in 1966, provides one of the highest steady-state neutron flux levels of any research reactor in the world. An ongoing vessel integrity analysis program to assess radiation-induced embrittlement of the HFIR reactor vessel requires the calculation of neutron and gamma displacements per atom (dpa), particularly at locations near the beam tube nozzles, where radiation streaming effects are most pronounced. In this study we apply the Forward-Weighted Consistent Adjoint Driven Importance Sampling (FW-CADIS) technique in the ADVANTG code to develop variance reduction parameters for use in the MCNP radiation transport code. We initially evaluated dpa rates for dosimetry capsule locations, regions in the vicinity of the HB-2 beamline, and the vessel beltline region. We then extended the study to provide dpa rate maps using three-dimensional cylindrical mesh tallies that extend from approximately 12 below to approximately 12 above the axial extent of the core. The mesh tally structures contain over 15,000 mesh cells, providing a detailed spatial map of neutron and photon dpa rates at all locations of interest. Relative errors in the mesh tally cells are typically less than 1%.

  1. Synthetic observations of first hydrostatic cores in collapsing low-mass dense cores. I. Spectral energy distributions and evolutionary sequence

    OpenAIRE

    Commercon, Benoit; Launhardt, Ralf; Dullemond, Cornelis P.; Henning, Thomas

    2012-01-01

    The low-mass star formation evolutionary sequence is relatively well-defined both from observations and theoretical considerations. The first hydrostatic core is the first protostellar equilibrium object that is formed during the star formation process. Using state-of-the-art radiation-magneto-hydrodynamic 3D adaptive mesh refinement calculations, we aim to provide predictions for the dust continuum emission from first hydrostatic cores. We investigate the collapse and the fragmentation of ma...

  2. Measuring the extent of convective cores in low-mass stars using Kepler data: toward a calibration of core overshooting

    Science.gov (United States)

    Deheuvels, S.; Brandão, I.; Silva Aguirre, V.; Ballot, J.; Michel, E.; Cunha, M. S.; Lebreton, Y.; Appourchaux, T.

    2016-05-01

    Context. Our poor understanding of the boundaries of convective cores generates large uncertainties on the extent of these cores and thus on stellar ages. The detection and precise characterization of solar-like oscillations in hundreds of main-sequence stars by CoRoT and Kepler has given the opportunity to revisit this problem. Aims: Our aim is to use asteroseismology to consistently measure the extent of convective cores in a sample of main-sequence stars whose masses lie around the mass limit for having a convective core. Methods: We first tested and validated a seismic diagnostic that was proposed to probe the extent of convective cores in a model-dependent way using the so-called r010 ratios, which are built with l = 0 and l = 1 modes. We applied this procedure to 24 low-mass stars chosen among Kepler targets to optimize the efficiency of this diagnostic. For this purpose, we computed grids of stellar models with both the Cesam2k and mesa evolution codes, where the extensions of convective cores were modeled either by an instantaneous mixing or as a diffusion process. Results: We found that 10 stars in our sample are in fact subgiants. Among the other targets, were able to unambiguously detect convective cores in eight stars, and we obtained seismic measurements of the extent of the mixed core in these targets with a good agreement between the Cesam2k and mesa codes. By performing optimizations using the Levenberg-Marquardt algorithm, we then obtained estimates of the amount of extra mixing beyond the core that is required in Cesam2k to reproduce seismic observations for these eight stars, and we showed that this can be used to propose a calibration of this quantity. This calibration depends on the prescription chosen for the extra mixing, but we found that it should also be valid for the code mesa, provided the same prescription is used. Conclusions: This study constitutes a first step toward calibrating the extension of convective cores in low-mass stars

  3. Status of lithium-filled specimen subcapsules for the HFIR-MFE-RB10J experiment

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, J.P.; Howell, M.; Lenox, K.E. [Oak Ridge National Lab., TN (United States)

    1998-09-01

    The HFIR-MFE-RB-10J experiment will be irradiated in a Removable Beryllium position in the HFIR for 10 reactor cycles, accumulating approximately 5 dpa in steel. The upper region of the capsule contains two lithium-filled subcapsules containing vanadium specimens. This report describes the techniques developed to achieve a satisfactory lithium fill with a specimen occupancy of 26% in each subcapsule.

  4. Design Analyses and Shielding of HFIR Cold Neutron Scattering Instruments

    Energy Technology Data Exchange (ETDEWEB)

    Gallmeier, F.X.; Selby, D.L.; Winn, B.; Stoica, D.; Jones, A.B.; Crow, L. [Neutron Sciences Directorate, Oak Ridge National Laboratory (United States)

    2011-07-01

    Research reactor geometries and special characteristics present unique dosimetry analysis and measurement issues. The introduction of a cold neutron moderator and the production of cold neutron beams at the Oak Ridge National Laboratory High Flux Isotope Reactor have created the need for modified methods and devices for analyzing and measuring low energy neutron fields (0.01 to 100 meV). These methods include modifications to an MCNPX version to provide modeling of neutron mirror reflection capability. This code has been used to analyze the HFIR cold neutron beams and to design new instrument equipment that will use the beams. Calculations have been compared with time-of-flight measurements performed at the start of the neutron guides and at the end of one of the guides. The results indicate that we have a good tool for analyzing the transport of these low energy beams through neutron mirror and guide systems for distance up to 60 meters from the reactor. (authors)

  5. Synthetic observations of first hydrostatic cores in collapsing low-mass dense cores. I. Spectral energy distributions and evolutionary sequence

    Science.gov (United States)

    Commerçon, B.; Launhardt, R.; Dullemond, C.; Henning, Th.

    2012-09-01

    Context. The low-mass star formation evolutionary sequence is relatively well-defined both from observations and theoretical considerations. The first hydrostatic core is the first protostellar equilibrium object that is formed during the star formation process. Aims: Using state-of-the-art radiation-magneto-hydrodynamic 3D adaptive mesh refinement calculations, we aim to provide predictions for the dust continuum emission from first hydrostatic cores. Methods: We investigated the collapse and the fragmentation of magnetized 1 M⊙ prestellar dense cores and the formation and evolution of first hydrostatic cores using the RAMSES code. We used three different magnetization levels for the initial conditions, which cover a wide variety of early evolutionary morphology, e.g., the formation of a disk or a pseudo-disk, outflow launching, and fragmentation. We post-processed the dynamical calculations using the 3D radiative transfer code RADMC-3D. We computed spectral energy distributions and usual evolutionary stage indicators such as bolometric luminosity and temperature. Results: We find that the first hydrostatic core lifetimes depend strongly on the initial magnetization level of the parent dense core. We derive, for the first time, spectral energy distribution evolutionary sequences from high-resolution radiation-magneto-hydrodynamic calculations. We show that under certain conditions, first hydrostatic cores can be identified from dust continuum emission at 24 μm and 70 μm. We also show that single spectral energy distributions cannot help in distinguishing between the formation scenarios of the first hydrostatic core, i.e., between the magnetized and non-magnetized models. Conclusions: Spectral energy distributions are a first useful and direct way to target first hydrostatic core candidates but high-resolution interferometry is definitively needed to determine the evolutionary stage of the observed sources.

  6. Search for methylamine in high mass hot cores

    CERN Document Server

    Ligterink, N F W; van Dishoeck, E F

    2015-01-01

    We aim to detect methylamine, CH$_{3}$NH$_{2}$, in a variety of hot cores and use it as a test for the importance of photon-induced chemistry in ice mantles and mobility of radicals. Specifically, CH$_3$NH$_2$ cannot be formed from atom addition to CO whereas other NH$_2$-containing molecules such as formamide, NH$_2$CHO, can. Submillimeter spectra of several massive hot core regions were taken with the James Clerk Maxwell Telescope. Abundances are determined with the rotational diagram method where possible. Methylamine is not detected, giving upper limit column densities between 1.9 $-$ 6.4 $\\times$ 10$^{16}$ cm$^{-2}$ for source sizes corresponding to the 100 K envelope radius. Combined with previously obtained JCMT data analyzed in the same way, abundance ratios of CH$_{3}$NH$_{2}$, NH$_{2}$CHO and CH$_{3}$CN with respect to each other and to CH$_{3}$OH are determined. These ratios are compared with Sagittarius B2 observations, where all species are detected, and to hot core models. The observed ratios su...

  7. Correlation between the Earth's Magnetic Field and the Gravitational Mass of the Outer Core

    OpenAIRE

    De Aquino, Fran

    2013-01-01

    The theory accepted today for the origin of the Earth's magnetic field is based on convection currents created in the Earth's outer core due to the rotational motion of the planet Earth around its own axis. In this work, we show that the origin of the Earth's magnetic field is related to the gravitational mass of the outer core.

  8. THE DEPENDENCE OF PRESTELLAR CORE MASS DISTRIBUTIONS ON THE STRUCTURE OF THE PARENTAL CLOUD

    Energy Technology Data Exchange (ETDEWEB)

    Parravano, Antonio [Centro De Fisica Fundamental, Universidad de Los Andes, Merida (Venezuela, Bolivarian Republic of); Sanchez, Nestor [S. D. Astronomia y Geodesia, Fac. CC. Matematicas, Universidad Complutense de Madrid (Spain); Alfaro, Emilio J. [Instituto de Astrofisica de Andalucia (CSIC), Granada (Spain)

    2012-08-01

    The mass distribution of prestellar cores is obtained for clouds with arbitrary internal mass distributions using a selection criterion based on the thermal and turbulent Jeans mass and applied hierarchically from small to large scales. We have checked this methodology by comparing our results for a log-normal density probability distribution function with the theoretical core mass function (CMF) derived by Hennebelle and Chabrier, namely a power law at large scales and a log-normal cutoff at low scales, but our method can be applied to any mass distributions representing a star-forming cloud. This methodology enables us to connect the parental cloud structure with the mass distribution of the cores and their spatial distribution, providing an efficient tool for investigating the physical properties of the molecular clouds that give rise to the prestellar core distributions observed. Simulated fractional Brownian motion (fBm) clouds with the Hurst exponent close to the value H = 1/3 give the best agreement with the theoretical CMF derived by Hennebelle and Chabrier and Chabrier's system initial mass function. Likewise, the spatial distribution of the cores derived from our methodology shows a surface density of companions compatible with those observed in Trapezium and Ophiucus star-forming regions. This method also allows us to analyze the properties of the mass distribution of cores for different realizations. We found that the variations in the number of cores formed in different realizations of fBm clouds (with the same Hurst exponent) are much larger than the expected root N statistical fluctuations, increasing with H.

  9. The Formation Mass of a Binary System via Fragmentation of a Rotating Parent Core with Increasing Total Mass

    CERN Document Server

    Arreaga-Garcia, Guillermo

    2016-01-01

    Recent VLA and CARMA observations have shown proto-stars in binaries with unprecedented resolution. Specifically, the proto-stellar masses of systems such as CB230 IRS1 and L1165-SMM1 have been detected in the range of $0.1-0.25 \\, M_{\\odot}$. These are much more massive than the masses generally obtained by numerical simulations of binary formation, around $0.01 \\, M_{\\odot}$. Motivated by these discrepancies in mass, in this paper we study the formation mass of a binary system as a function of the total mass of its parent core. To achieve this objective, we present a set of numerical simulations of the gravitational collapse of a uniform and rotating core, in which azimuthal symmetric mass seeds are initially implemented in order to favor the formation of a dense filament, out of which a binary system may be formed by direct fragmentation. We first observed that this binary formation process is diminished when the total mass of the parent core $M_0$ is increased; then we increased the level of the ratio of ...

  10. High Flux Isotopes Reactor (HFIR) Cooling Towers Demolition Waste Management

    Energy Technology Data Exchange (ETDEWEB)

    Pudelek, R. E.; Gilbert, W. C.

    2002-02-26

    This paper describes the results of a joint initiative between Oak Ridge National Laboratory, operated by UT-Battelle, and Bechtel Jacobs Company, LLC (BJC) to characterize, package, transport, treat, and dispose of demolition waste from the High Flux Isotope Reactor (HFIR), Cooling Tower. The demolition and removal of waste from the site was the first critical step in the planned HFIR beryllium reflector replacement outage scheduled. The outage was scheduled to last a maximum of six months. Demolition and removal of the waste was critical because a new tower was to be constructed over the old concrete water basin. A detailed sampling and analysis plan was developed to characterize the hazardous and radiological constituents of the components of the Cooling Tower. Analyses were performed for Resource Conservation and Recovery Act (RCRA) heavy metals and semi-volatile constituents as defined by 40 CFR 261 and radiological parameters including gross alpha, gross beta, gross gamma, alpha-emitting isotopes and beta-emitting isotopes. Analysis of metals and semi-volatile constituents indicated no exceedances of regulatory limits. Analysis of radionuclides identified uranium and thorium and associated daughters. In addition 60Co, 99Tc, 226Rm, and 228Rm were identified. Most of the tower materials were determined to be low level radioactive waste. A small quantity was determined not to be radioactive, or could be decontaminated. The tower was dismantled October 2000 to January 2001 using a detailed step-by-step process to aid waste segregation and container loading. The volume of waste as packaged for treatment was approximately 1982 cubic meters (70,000 cubic feet). This volume was comprised of plastic ({approx}47%), wood ({approx}38%) and asbestos transite ({approx}14%). The remaining {approx}1% consisted of the fire protection piping (contaminated with lead-based paint) and incidental metal from conduit, nails and braces/supports, and sludge from the basin. The waste

  11. Massive Infrared-Quiet Dense Cores: Unveiling the Initial Conditions of High-Mass Star Formation

    CERN Document Server

    Motte, Frédérique; Schneider, N; Schilke, P; Menten, K M

    2008-01-01

    As Pr. Th. Henning said at the conference, cold precursors of high-mass stars are now "hot topics". We here propose some observational criteria to identify massive infrared-quiet dense cores which can host the high-mass analogs of Class 0 protostars and pre-stellar condensations. We also show how far-infrared to millimeter imaging surveys of entire complexes forming OB stars are starting to unveil the initial conditions of high-mass star formation.

  12. Mass Redistribution in the Core and Time-varying Gravity at the Earth's Surface

    Science.gov (United States)

    Kuang, Wei-Jia; Chao, Benjamin F.; Fang, Ming

    2003-01-01

    The Earth's liquid outer core is in convection, as suggested by the existence of the geomagnetic field in much of the Earth's history. One consequence of the convection is the redistribution of mass resulting from relative motion among fluid parcels with slightly different densities. This time dependent mass redistribution inside the core produces a small perturbation on the gravity field of the Earth. With our numerical dynamo solutions, we find that the mass redistribution (and the resultant gravity field) symmetric about the equator is much stronger than that anti-symmetric about the equator. In particular, J(sub 2) component is the strongest. In addition, the gravity field variation increases with the Rayleigh number that measures the driving force for the geodynamo in the core. With reasonable scaling from the current dynamo solutions, we could expect that at the surface of the Earth, the J(sub 2) variation from the core is on the order of l0(exp -16)/year relative to the mean (i.e. spherically symmetric) gravity field of the Earth. The possible shielding effect due to core-mantle boundary pressure variation loading is likely much smaller and is therefore negligible. Our results suggest that time-varying gravity field perturbation due to core mass redistribution may be measured with modem space geodetic observations, which will result a new means of detecting dynamical processes in the Earth's deep interior.

  13. Mass Redistribution in the Core and Time-varying Gravity at the Earth's Surface

    Science.gov (United States)

    Kuang, Wei-Jia; Chao, Benjamin F.; Fang, Ming

    2003-01-01

    The Earth's liquid outer core is in convection, as suggested by the existence of the geomagnetic field in much of the Earth's history. One consequence of the convection is the redistribution of mass resulting from relative motion among fluid parcels with slightly different densities. This time dependent mass redistribution inside the core produces a small perturbation on the gravity field of the Earth. With our numerical dynamo solutions, we find that the mass redistribution (and the resultant gravity field) symmetric about the equator is much stronger than that anti-symmetric about the equator. In particular, J(sub 2) component is the strongest. In addition, the gravity field variation increases with the Rayleigh number that measures the driving force for the geodynamo in the core. With reasonable scaling from the current dynamo solutions, we could expect that at the surface of the Earth, the J(sub 2) variation from the core is on the order of l0(exp -16)/year relative to the mean (i.e. spherically symmetric) gravity field of the Earth. The possible shielding effect due to core-mantle boundary pressure variation loading is likely much smaller and is therefore negligible. Our results suggest that time-varying gravity field perturbation due to core mass redistribution may be measured with modem space geodetic observations, which will result a new means of detecting dynamical processes in the Earth's deep interior.

  14. Materials Selection for the HFIR Cold Neutron Source

    Energy Technology Data Exchange (ETDEWEB)

    Farrell, K.

    2001-08-24

    In year 2002 the High Flux Isotope Reactor (HFIR) will be fitted with a source of cold neutrons to upgrade and expand its existing neutron scattering facilities. The in-reactor components of the new source consist of a moderator vessel containing supercritical hydrogen gas moderator at a temperature of 20K and pressure of 15 bar, and a surrounding vacuum vessel. They will be installed in an enlarged beam tube located at the site of the present horizontal beam tube, HB-4; which terminates within the reactor's beryllium reflector. These components must withstand exceptional service conditions. This report describes the reasons and factors underlying the choice of 6061-T6 aluminum alloy for construction of the in-reactor components. The overwhelming considerations are the need to minimize generation of nuclear heat and to remove that heat through the flowing moderator, and to achieve a minimum service life of about 8 years coincident with the replacement schedule for the beryllium reflector. 6061-T6 aluminum alloy offers the best combination of low nuclear heating, high thermal conductivity, good fabricability, compatibility with hydrogen, superior cryogenic properties, and a well-established history of satisfactory performance in nuclear environments. These features are documented herein. An assessment is given of the expected performance of each component of the cold source.

  15. Role of percutaneous needle core biopsy in diagnosis and clinical management of renal masses.

    Science.gov (United States)

    Hu, Rong; Montemayor-Garcia, Celina; Das, Kasturi

    2015-04-01

    Percutaneous needle core biopsies are routinely performed for renal mass diagnosis in some institutions. Because of limited tissue availability, accurate diagnosis can be challenging, and the role of needle core biopsy (NCB) remains debatable in kidney tumor management. In the present study, we reported our experience in diagnosing renal masses via percutaneous NCB and the role it plays in clinical management of these masses. We studied 301 consecutive cases of percutaneous NCBs performed for 280 renal masses from 269 patients between year 2008 and 2011 by reviewing final pathology diagnosis, hematoxylin and eosin slides, and ancillary studies. Diagnostic accuracy was determined by comparing biopsy and nephrectomy diagnoses in a subset of renal masses. Clinical data including demographic information, clinical presentation, radiographic findings, and treatment information were reviewed subsequently if available. The size of renal masses in our study cohort ranged from 0.5 to 24 cm, and 78% of them were small renal masses. Definite diagnoses were rendered in 89% of the renal masses by NCBs, and 23% of them were benign. Renal mass NCB was 100% accurate in diagnosing primary renal malignancy and 93% accurate in determining histologic subtypes. Clinical management was analyzed for 180 renal masses. There was significant difference in clinical management between different diagnostic groups. We conclude that percutaneous NCB is a powerful tool not only for definite tissue diagnosis of renal masses before treatment but also plays an important role in guiding patient management and obtaining material for future molecular studies for targeted therapies.

  16. A prevalence of dynamo-generated magnetic fields in the cores of intermediate-mass stars.

    Science.gov (United States)

    Stello, Dennis; Cantiello, Matteo; Fuller, Jim; Huber, Daniel; García, Rafael A; Bedding, Timothy R; Bildsten, Lars; Aguirre, Victor Silva

    2016-01-21

    Magnetic fields play a part in almost all stages of stellar evolution. Most low-mass stars, including the Sun, show surface fields that are generated by dynamo processes in their convective envelopes. Intermediate-mass stars do not have deep convective envelopes, although 10 per cent exhibit strong surface fields that are presumed to be residuals from the star formation process. These stars do have convective cores that might produce internal magnetic fields, and these fields might survive into later stages of stellar evolution, but information has been limited by our inability to measure the fields below the stellar surface. Here we report the strength of dipolar oscillation modes for a sample of 3,600 red giant stars. About 20 per cent of our sample show mode suppression, by strong magnetic fields in the cores, but this fraction is a strong function of mass. Strong core fields occur only in red giants heavier than 1.1 solar masses, and the occurrence rate is at least 50 per cent for intermediate-mass stars (1.6-2.0 solar masses), indicating that powerful dynamos were very common in the previously convective cores of these stars.

  17. Chemical and Physical Characterization of Collapsing Low-mass Prestellar Dense Cores

    Science.gov (United States)

    Hincelin, U.; Commerçon, B.; Wakelam, V.; Hersant, F.; Guilloteau, S.; Herbst, E.

    2016-05-01

    The first hydrostatic core, also called the first Larson core, is one of the first steps in low-mass star formation as predicted by theory. With recent and future high-performance telescopes, the details of these first phases are becoming accessible, and observations may confirm theory and even present new challenges for theoreticians. In this context, from a theoretical point of view, we study the chemical and physical evolution of the collapse of prestellar cores until the formation of the first Larson core, in order to better characterize this early phase in the star formation process. We couple a state-of-the-art hydrodynamical model with full gas-grain chemistry, using different assumptions for the magnetic field strength and orientation. We extract the different components of each collapsing core (i.e., the central core, the outflow, the disk, the pseudodisk, and the envelope) to highlight their specific physical and chemical characteristics. Each component often presents a specific physical history, as well as a specific chemical evolution. From some species, the components can clearly be differentiated. The different core models can also be chemically differentiated. Our simulation suggests that some chemical species act as tracers of the different components of a collapsing prestellar dense core, and as tracers of the magnetic field characteristics of the core. From this result, we pinpoint promising key chemical species to be observed.

  18. The mass effect of the quark phase transition in supernova core

    Institute of Scientific and Technical Information of China (English)

    Lai Xiang-Jun; Liu Men-Quan; Liu Jing-Jing; Luo Zhi-Quan

    2008-01-01

    Constituent quark mass model is adopted as a tentative one to study the phase transition between two-flavour quark matter and more stable thres-flavour quark matter in the core of supernovae.The result shows that the transition has a significant influence on the increasing of the core temperature,the neutrino abundance and the neutrino energies,which contributes to the enhancement of the successful probability of supernova explosion.However,the equilibrium values of these parameters (except the temperature) from the constituent quark mass model in this work are slightly bigger than those obtained from the other model.And we find that the constituent quark mass model is also applicable to describing the transition in the supernova core.

  19. High Angular Resolution Observations of Four Candidate BLAST High-Mass Starless Cores

    CERN Document Server

    Olmi, Luca; Chapin, Edward L; Gibb, Andrew; Hofner, Peter; Martin, Peter G; Poventud, Carlos M

    2010-01-01

    We discuss high-angular resolution observations of ammonia toward four candidate high-mass starless cores (HMSCs). The cores were identified by the Balloon-borne Large Aperture Submillimeter Telescope (BLAST) during its 2005 survey of the Vulpecula region where 60 compact sources were detected simultaneously at 250, 350, and 500 micron. Four of these cores, with no IRAS-PSC or MSX counterparts, were observed with the NRAO Very Large Array (VLA) in the NH3(1,1) and (2,2) spectral lines. Our observations indicate that the four cores are cold (Tk <~ 14K) and show a filamentary and/or clumpy structure. They also show a significant velocity substructure within ~1km/s. The four BLAST cores appear to be colder and more quiescent than other previously observed HMSC candidates, suggesting an earlier stage of evolution.

  20. The Core Mass Growth and Stellar Lifetime of Thermally Pulsing Asymptotic Giant Branch Stars

    CERN Document Server

    Kalirai, Jason S; Tremblay, Pier-Emmanuel

    2013-01-01

    We establish new constraints on the intermediate-mass range of the initial-final mass relation by studying white dwarfs in four young star clusters, and apply the results to study the evolution of stars on the thermally pulsing asymptotic giant branch (TP-AGB). We show that the stellar core mass on the AGB grows rapidly from 10% to 30% for stars with $M_{\\rm initial}$ = 1.6 to 2.0 $M_\\odot$. At larger masses, the core-mass growth decreases steadily to $\\sim$10% at $M_{\\rm initial}$ = 3.4 $M_\\odot$. These observations are in excellent agreement with predictions from the latest TP-AGB evolutionary models in Marigo et al. (2013). We also compare to models with varying efficiencies of the third dredge-up and mass loss, and demonstrate that the process governing the growth of the core is largely the stellar wind, while the third dredge-up plays a secondary, but non-negligible role. Based on the new white dwarf measurements, we perform an exploratory calibration of the most popular mass-loss prescriptions in the li...

  1. Mapping the core mass function onto the stellar IMF: multiplicity matters

    CERN Document Server

    Holman, K; Goodwin, S P; Whitworth, A P

    2013-01-01

    Observations indicate that the central portions of the Present-Day Prestellar Core Mass Function (CMF) and the Stellar Initial Mass Function (IMF) both have approximately log-normal shapes, but that the CMF is displaced to higher mass than the IMF by a factor F = 4+/-1. This has lead to suggestions that the shape of the IMF is directly inherited from the shape of the CMF - and therefore, by implication, that there is a self-similar mapping from the CMF onto the IMF. If we assume a self-similar mapping, it follows (i) that F = N0/eta, where eta is the mean fraction of a core's mass that ends up in stars, and N0 is the mean number of stars spawned by a single core; and (ii) that the stars spawned by a single core must have an approximately log-normal distribution of relative masses, with universal standard deviation sigma0. Observations can be expected to deliver ever more accurate estimates of F, but this still leaves a degeneracy between eta and N0; and sigma0 is also unconstrained by observation. Here we sho...

  2. High mass-resolution electron-ion-ion coincidence measurements on core-excited organic molecules

    CERN Document Server

    Tokushima, T; Senba, Y; Yoshida, H; Hiraya, A

    2001-01-01

    Total electron-ion-ion coincidence measurements on core excited organic molecules have been carried out with high mass resolution by using multimode (reflectron/linear) time-of-flight mass analyzer. From the ion correlation spectra of core excited CH sub 3 OH and CD sub 3 OH, the reaction pathway to form H sub 3 sup + (D sub 3 sup +) is identified as the elimination of three H (D) atoms from the methyl group, not as the inter-group (-CH sub 3 and -OH) interactions. In a PEPIPICO spectrum of acetylacetone (CH sub 3 COCH sub 2 COCH sub 3) measured by using a reflectron TOF, correlations between ions up to mass number 70 with one-mass resolution was recorded.

  3. The SNS/HFIR Web Portal System for SANS

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, Stuart I [ORNL; Miller, Stephen D [ORNL; Bilheux, Jean-Christophe [ORNL; Reuter, Michael A [ORNL; Peterson, Peter F [ORNL; Kohl, James Arthur [ORNL; Trater, James R [ORNL; Vazhkudai, Sudharshan S [ORNL; Lynch, Vickie E [ORNL

    2010-01-01

    In a busy world, continuing with the status-quo, to do things the way we are already familiar, often seems to be the most efficient way to conduct our work. We look for the value-add to decide if investing in a new method is worth the effort. How shall we evaluate if we have reached this tipping point for change? For contemporary researchers, understanding the properties of the data is a good starting point. The new generation of neutron scattering instruments being built are higher resolution and produce one or more orders of magnitude larger data than the previous generation of instruments. For instance, we have grown out of being able to perform some important tasks with our laptops the data are too big and the computations would simply take too long. These large datasets can be problematic as facility users now begin to grapple with many of the same issues faced by more established computing communities. These issues include data access, management, and movement, data format standards, distributed computing, and collaboration among others. The Neutron Science Portal has been architected, designed, and implemented to provide users with an easy-to-use interface for managing and processing data, while also keeping an eye on meeting modern cybersecurity requirements imposed on institutions. The cost of entry for users has been lowered by utilizing a web interface providing access to backend portal resources. Users can browse or search for data which they are allowed to see, data reduction applications can be run without having to load the software, sample activation calculations can be performed for SNS and HFIR beamlines, McStas simulations can be run on TeraGrid and ORNL computers, and advanced analysis applications such as those being produced by the DANSE project can be run. Behind the scenes is a live cataloging system which automatically catalogs and archives experiment data via the data management system, and provides proposal team members access to their

  4. Analytical Core Mass Function (CMF) from Filaments: Under Which Circumstances Can Filament Fragmentation Reproduce the CMF?

    Science.gov (United States)

    Lee, Yueh-Ning; Hennebelle, Patrick; Chabrier, Gilles

    2017-10-01

    Observations suggest that star formation in filamentary molecular clouds occurs in a two-step process, with the formation of filaments preceding that of prestellar cores and stars. Here, we apply the gravoturbulent fragmentation theory of Hennebelle & Chabrier to a filamentary environment, taking into account magnetic support. We discuss the induced geometrical effect on the cores, with a transition from 3D geometry at small scales to 1D at large ones. The model predicts the fragmentation behavior of a filament for a given mass per unit length (MpL) and level of magnetization. This core mass function (CMF) for individual filaments is then convolved with the distribution of filaments to obtain the final system CMF. The model yields two major results. (i) The filamentary geometry naturally induces a hierarchical fragmentation process, first into groups of cores, separated by a length equal to a few filament Jeans lengths, i.e., a few times the filament width. These groups then fragment into individual cores. (ii) Non-magnetized filaments with high MpL are found to fragment excessively, at odds with observations. This is resolved by taking into account the magnetic field (treated simply as additional pressure support). The present theory suggests two complementary modes of star formation: although small (spherical or filamentary) structures will collapse directly into prestellar cores, according to the standard Hennebelle–Chabrier theory, the large (filamentary) ones, the dominant population according to observations, will follow the aforedescribed two-step process.

  5. The Supermassive Black Hole Mass - Spheroid Stellar Mass Relation for S\\'ersic and Core-S\\'ersic Galaxies

    CERN Document Server

    Scott, Nicholas; Schombert, James

    2013-01-01

    We have examined the relationship between supermassive black hole mass (M_BH) and the stellar mass of the host spheroid (M_sph,*) for a sample of 75 nearby galaxies. To derive the spheroid stellar masses we used improved 2MASS K_s-band photometry from the ARCHANGEL photometry pipeline. Dividing our sample into core-S\\'ersic and S\\'ersic galaxies, we find that they are described by very different M_BH-M_sph,* relations. For core-S\\'ersic galaxies - which are typically massive and luminous, with M_BH \\gtrsim 2x10^8 M_solar - we find M_BH \\propto M_sph,*^(0.97 \\pm 0.14), consistent with other literature relations. However, for the S\\'ersic galaxies - with typically lower masses, M_sph,* \\lesssim 3x10^10 M_solar - we find M_BH \\propto M_sph,*^(2.22 \\pm 0.58), a dramatically steeper slope that differs by more than 2 standard deviations. This relation confirms that, for S\\'ersic galaxies, M_BH is not a constant fraction of M_sph,*. S\\'ersic galaxies can grow via the accretion of gas which fuels both star formation ...

  6. Correlations Between Supermassive Black Holes, Velocity Dispersions, and Mass Deficits in Elliptical Galaxies with Cores

    CERN Document Server

    Kormendy, John; 10.1088/0004-637X/691/2/L142

    2009-01-01

    High-dynamic-range surface photometry in a companion paper makes possible accurate measurement of the stellar light deficits L_def and mass deficits M_def associated with the cores of elliptical galaxies. We show that L_def correlates with the velocity dispersion sigma of the host galaxy bulge averaged outside the central region that may be affected by a supermassive black hole (BH). We confirm that L_def correlates with BH mass MBH. Also, the fractional light deficit L_def/L correlates with MBH/M, the ratio of BH mass to the galaxy stellar mass. All three correlations have scatter similar to or smaller than the scatter in the well known correlation between MBH and sigma. The new correlations are remarkable in view of the dichotomy between ellipticals with cores and those with central extra light. Core light deficit correlates closely with MBH and sigma, but extra light does not. This supports the suggestion that extra light Es are made in wet mergers with starbursts whereas core Es are made in dry mergers. A...

  7. The hot core around the low-mass protostar IRAS 16293-2422 : Scoundrels rule!

    NARCIS (Netherlands)

    Cazaux, S; Tielens, AGGM; Ceccarelli, C; Castets, A; Wakelam, [No Value; Caux, E; Parise, B; Teyssier, D

    2003-01-01

    While warm dense gas is prevalent around low-mass protostars, the presence of complex saturated molecules-the chemical inventory characteristic of hot cores-has remained elusive in such environments. Here we report the results of an IRAM 30 m study of the molecular composition associated with the lo

  8. Continuous ice-core chemical analyses using inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    McConnell, Joseph R; Lamorey, Gregg W; Lambert, Steven W; Taylor, Kendrick C

    2002-01-01

    Impurities trapped in ice sheets and glaciers have the potential to provide detailed, high temporal resolution proxy information on paleo-environments, atmospheric circulation, and environmental pollution through the use of chemical, isotopic, and elemental tracers. We present a novel approach to ice-core chemical analyses in which an ice-core melter is coupled directly with both an inductively coupled plasma mass spectrometer and a traditional continuous flow analysis system. We demonstrate this new approach using replicated measurements of ice-core samples from Summit, Greenland. With this method, it is possible to readily obtain continuous, exactly coregistered concentration records for a large number of elements and chemical species at ppb and ppt levels and at unprecedented depth resolution. Such very-high depth resolution, multiparameter measurements will significantly expand the use of ice-core records for environmental proxies.

  9. Simulation of heat and mass transfer processes in molten core debris-concrete systems. [LMFBR

    Energy Technology Data Exchange (ETDEWEB)

    Felde, D K

    1979-01-01

    The heat and mass transport phenomena taking place in volumetrically-heated fluids have become of interest in recent years due to their significance in assessments of fast reactor safety and post-accident heat removal (PAHR). Following a hypothetical core disruptive accident (HCDA), the core and reactor internals may melt down. The core debis melting through the reactor vessel and guard vessel may eventually contact the concrete of the reactor cell floor. The interaction of the core debris with the concrete as well as the melting of the debris pool into the concrete will significantly affect efforts to prevent breaching of the containment and the resultant release of radioactive effluents to the environment.

  10. In-situ measurement of the electrical conductivity of aluminum oxide in HFIR

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J.; White, D.P.; Snead, L.L. [Oak Ridge National Lab., TN (United States)] [and others

    1996-10-01

    A collaborative DOE/Monbusho irradiation experiment has been completed which measured the in-situ electrical resistivity of 12 different grades of aluminum oxide during HFIR neutron irradiation at 450{degrees}C. No evidence for bulk RIED was observed following irradiation to a maximum dose of 3 dpa with an applied dc electric field of 200 V/mm.

  11. Countercurrent flow limited (CCFL) heat flux in the high flux isotope reactor (HFIR) fuel element

    Energy Technology Data Exchange (ETDEWEB)

    Ruggles, A.E.

    1990-10-12

    The countercurrent flow (CCF) performance in the fuel element region of the HFIR is examined experimentally and theoretically. The fuel element consists of two concentric annuli filled with aluminum clad fuel plates of 1.27 mm thickness separated by 1.27 mm flow channels. The plates are curved as they go radially outward to accomplish constant flow channel width and constant metal-to-coolant ratio. A full-scale HFIR fuel element mock-up is studied in an adiabatic air-water CCF experiment. A review of CCF models for narrow channels is presented along with the treatment of CCFs in system of parallel channels. The experimental results are related to the existing models and a mechanistic model for the annular'' CCF in a narrow channel is developed that captures the data trends well. The results of the experiment are used to calculate the CCFL heat flux of the HFIR fuel assembly. It was determined that the HFIR fuel assembly can reject 0.62 Mw of thermal power in the CCFL situation. 31 refs., 17 figs.

  12. Sensitive Limits on the Water Abundance in Cold Low Mass Molecular Cores

    CERN Document Server

    Bergin, E A; Bergin, Edwin A.; Snell, Ronald L.

    2002-01-01

    We present SWAS observations of water vapor in two cold star-less clouds, B68 and Core D in rho Ophiuchus. Sensitive non-detections of the 1(10)-1(01) transition of o-H2O are reported for each source. Both molecular cores have been previously examined by detailed observations that have characterized the physical structure. Using these rather well defined physical properties and a Monte-Carlo radiation transfer model we have removed one of the largest uncertainties from the abundance calculation and set the lowest water abundance limit to date in cold low-mass molecular cores. These limits are < 3 x 10^{-8} (relative to H2) and < 8 x 10^{-9} in B68 and rho Oph D, respectively. Such low abundances confirm the general lack of ortho-water vapor in cold (T < 20 K) cores. Provided that the ortho/para ratio of water is not near zero, these limits are well below theoretical predictions and appear to support the suggestion that most of the water in dense low-mass cores is frozen onto the surfaces of cold dust...

  13. A modified triple test for palpable breast masses: the value of ultrasound and core needle biopsy.

    Science.gov (United States)

    Wai, Christina J; Al-Mubarak, Ghada; Homer, Marc J; Goldkamp, Allison; Samenfeld-Specht, Marja; Lee, Yoojin; Logvinenko, Tanya; Rothschild, Janice G; Graham, Roger A

    2013-03-01

    The original triple test score (TTS)--clinical examination, mammogram, and fine-needle aspiration (FNA) biopsy--has long been used to evaluate palpable breast masses. We modified the original TTS to include ultrasound (US) and core biopsy to determine their role in evaluating palpable breast masses. A retrospective chart review of 320 female patients was performed. We developed a modified triple test score (mTTS) that included physical examination, mammogram and/or US, and FNA and/or core biopsy. For the examination and imaging score, 1-3 points were given for low, moderate, or high suspicion. Biopsy scores were characterized as benign, atypical, or malignant. Final outcome was determined by open biopsy or follow-up greater than 1 year. Physical examination was 92% accurate (95% confidence interval [CI] 0.89-0.96, p core biopsy changed the scores of 24 patients; only three changed clinical management. For patients with a palpable breast mass and a mTTS score of 3-4, no further assessment is necessary. Those with a mTTS of 8-9 can proceed to definitive therapy. Patients with a mTTS of 5-7 require further assessment. US and/or core biopsy added little to the accuracy or predictive value of the original TTS.

  14. Physical and chemical structure of dense cores in regions of high mass star formation

    CERN Document Server

    Zinchenko, A I; Caselli, P; Johansson, L E B; Malafeev, S; Turner, B; Zinchenko, Igor; Pirogov, Lev; Caselli, Paola; Johansson, Lars E.B.; Malafeev, Sergey; Turner, Barry

    2005-01-01

    We found that in regions of high mass star formation the CS emission correlates well with the dust continuum emission and is therefore a good tracer of the total mass while the N$_2$H$^+$ distribution is frequently very different. This is opposite to their typical behavior in low-mass cores where freeze-out plays a crucial role in the chemistry. The behavior of other high density tracers varies from source to source but most of them are closer to CS. Radial density profiles in massive cores are fitted by power laws with indices about -1.6, as derived from the dust continuum emission. The radial temperature dependence on intermediate scales is close to the theoretically expected one for a centrally heated optically thin cloud. The velocity dispersion either remains constant or decreases from the core center to the edge. Several cores including those without known embedded IR sources show signs of infall motions. They can represent the earliest phases of massive protostars. There are implicit arguments in favor...

  15. Pre-menarcheal physical activity predicts post-menarcheal lean mass and core strength, but not fat mass.

    Science.gov (United States)

    Day, M A; Dowthwaite, J N; Rosenbaum, P F; Roedel, G G; Brocker, A A; Scerpella, T A

    2015-12-01

    Youth exercise is associated with improved body composition, but details regarding timing and persistence are limited. We examined pre- and circum-menarcheal organized physical activity exposure (PA) as a factor in development of early post-menarcheal lean mass, fat mass and muscle strength. Participants in a longitudinal study of musculoskeletal growth using dual energy X-ray absorptiometry (DXA) were included based on: 1) Whole body DXA scans: 0.5-1.5 years pre-menarche, 0.5-1.5 years post-menarche; 2) PA records for ⋝6 months preceding the first DXA (prePA) and for the inter-DXA interval (circumPA). Dominant arm grip strength and sit-ups tests coincided with DXA scans; PA, height and maturity were recorded semi-annually. Regressions correlated PA with lean mass/fat mass/strength, accounting for maturity, body size, and baseline values. Seventy girls [baseline: 11.8 yrs (sd 1.0), follow-up: 13.9 years (sd 1.0)] demonstrated circum-menarcheal gains of 25-29% for lean and fat mass and 33% for grip strength. PREPA correlated with pre- and post-menarcheal lean mass, sit-ups and pre-menarcheal fat mass (pstrength. CIRCUMPA correlated with only post-menarcheal sub-head lean mass (p=0.03). Lean mass and core strength at 1-year post-menarche were more strongly predicted by pre-menarcheal organized PA than by recent circum-menarcheal PA.

  16. Chemical and physical characterization of collapsing low-mass prestellar dense cores

    CERN Document Server

    Hincelin, U; Wakelam, V; Hersant, F; Guilloteau, S; Herbst, E

    2016-01-01

    The first hydrostatic core, also called the first Larson core, is one of the first steps in low-mass star formation, as predicted by theory. With recent and future high performance telescopes, details of these first phases become accessible, and observations may confirm theory and even bring new challenges for theoreticians. In this context, we study from a theoretical point of view the chemical and physical evolution of the collapse of prestellar cores until the formation of the first Larson core, in order to better characterize this early phase in the star formation process. We couple a state-of-the-art hydrodynamical model with full gas-grain chemistry, using different assumptions on the magnetic field strength and orientation. We extract the different components of each collapsing core (i.e., the central core, the outflow, the disk, the pseudodisk, and the envelope) to highlight their specific physical and chemical characteristics. Each component often presents a specific physical history, as well as a sp...

  17. Multiple low-turbulence starless cores associated with intermediate- to high-mass star formation

    Science.gov (United States)

    Beuther, H.; Henning, Th.

    2009-09-01

    Aims: Characterizing the gas and dust properties prior to and in the neighborhood of active intermediate- to high-mass star formation. Methods: Two Infrared Dark Clouds (IRDCs) - IRDC 19175-4 and IRDC 19175-5 - that are located in the vicinity of the luminous massive star-forming region IRAS 19175+1357, but that remain absorption features up to 70 μm wavelength, were observed with the Plateau de Bure Interferometer in the 3.23 mm dust continuum as well as the N2H^+(1-0) and 13CS(2-1) line emission. Results: While IRDC 19175-4 is clearly detected in the 3.23 mm continuum, the second source in the field, IRDC 19175-5, is only barely observable above the 3σ continuum detection threshold. However, the N2H^+(1-0) observations reveal 17 separate sub-sources in the vicinity of the two IRDCs. Most of them exhibit low levels of turbulence (Δ v ≤ 1 km s-1), indicating that the fragmentation process in these cores may be dominated by the interplay of thermal pressure and gravity, but not so much by turbulence. Combining the small line widths with the non-detection up to 70 μm and the absence of other signs of star formation activity, most of these 17 cores with masses between sub-solar to ~10 M⊙ are likely still in a starless phase. The N2H+ column density analysis indicates significant abundance variations between the cores. Furthermore, we find a large CS depletion factor of the order 100. Although the strongest line and continuum peak is close to virial equilibrium, its slightly broader line width compared to the other cores is consistent with it being in a contraction phase potentially at the verge of star formation. Based on the 3.23 mm upper limits, the other cores may be gravitationally stable or even transient structures. The relative peak velocities between neighboring cores are usually below 1 km s-1, and we do not identify streaming motions along the filamentary structures. Average densities are between 105 and 106 cm-3 (one to two orders of magnitude

  18. A prevalence of dynamo-generated magnetic fields in the cores of intermediate-mass stars

    CERN Document Server

    Stello, D; Fuller, J; Huber, D; Garcia, R A; Bedding, T R; Bildsten, L; Aguirre, V Silva

    2016-01-01

    Magnetic fields play a role in almost all stages of stellar evolution. Most low-mass stars, including the Sun, show surface fields that are generated by dynamo processes in their convective envelopes. Intermediate-mass stars do not have deep convective envelopes, although 10% exhibit strong surface fields that are presumed to be residuals from the stellar formation process. These stars do have convective cores that might produce internal magnetic fields, and these might even survive into later stages of stellar evolution, but information has been limited by our inability to measure the fields below the stellar surface. Here we use asteroseismology to study the occurrence of strong magnetic fields in the cores of low- and intermediate-mass stars. We have measured the strength of dipolar oscillation modes, which can be suppressed by a strong magnetic field in the core, in over 3600 red giant stars observed by Kepler. About 20% of our sample show mode suppression but this fraction is a strong function of mass. S...

  19. Dust in Protoplanetary Disks: A Clue as to the Critical Mass of Planetary Cores

    CERN Document Server

    Hasegawa, Yasuhiro

    2014-01-01

    Dust in protoplanetary disks is recognized as the building blocks of planets. In the core accretion scenario, the abundance of dust in disks (or metallicity) is crucial for forming cores of gas giants. We present our recent progress on the relationship between the metallicity and planet formation, wherein planet formation frequencies (PFFs) as well as the critical mass of planetary cores ($M_{c,crit}$) that can initiate gas accretion are statistically examined. We focus on three different planetary populations that are prominent for observed exoplanets in the mass-semimajor axis diagram: hot Jupiters, exo-Jupiters that are densely populated around 1 AU, and low-mass planets in tight orbits. We show that the resultant PFFs for both Jovian planets are correlated positively with the metallicity whereas low-mass planets form efficiently for a wide range of metallicities. This is consistent with the observed Planet-Metallicity correlation. Examining the statistically averaged value of $M_{c,crit}$ (defined as $$),...

  20. Low-mass gas envelopes around accreting cores embedded in radiative 3D discs

    Science.gov (United States)

    Lega, Elena; Lambrechts, Michiel

    2016-10-01

    Planets with a core mass larger than few Earth masses and a gaseous envelope not exceeding about 10% of the total mass budget are common. Such planets are present in the Solar System (Uranus, Neptune) and are frequently observed around other stars.Our knowledge about the evolution of gas envelopes is mainly based on 1D models. However, such models cannot investigate the complex interaction between the forming envelope and the surrounding gas disc.In this work we perform 3D hydrodynamics simulations accounting for energy transfer and radiative cooling using the FARGOCA code (Lega et al., MNRAS 440, 2014). In addition to the usually considered heatingsources, namely viscous and compressional heating, we have modeled the energy deposited by the accretion of solids.We show that the thermal evolution of the envelope of a 5 Earth mass core is mainly dominated by compressional heating for accretion rates lower than 5 Earth masses per 105 years.Additionally, we demonstrate efficient gas circulation through the envelope. Under certain conditions, the competition between gas circulation and cooling of the envelope can efficiently delay the onset of runaway accretion. This could help in explaining the population of planets with low-mass gas envelope.

  1. Critical core mass for enriched envelopes: the role of H2O condensation

    CERN Document Server

    Venturini, J; Benz, W; Ikoma, M

    2015-01-01

    Context. Within the core accretion scenario of planetary formation, most simulations performed so far always assume the accreting envelope to have a solar composition. From the study of meteorite showers on Earth and numerical simulations, we know that planetesimals must undergo thermal ablation and disruption when crossing a protoplanetary envelope. Once the protoplanet has acquired an atmosphere, the primordial envelope gets enriched in volatiles and silicates from the planetesimals. This change of envelope composition during the formation can have a significant effect in the final atmospheric composition and on the formation timescale of giant planets. Aims. To investigate the physical implications of considering the envelope enrichment of protoplanets due to the disruption of icy planetesimals during their way to the core. Particular focus is placed on the effect on the critical core mass for envelopes where condensation of water can occur. Methods. Internal structure models are numerically solved with th...

  2. Recent advances in the theoretical modeling of pulsating low-mass He-core white dwarfs

    CERN Document Server

    Córsico, A H; Calcaferro, L M; Serenelli, A M; Kepler, S O; Jeffery, C S

    2016-01-01

    Many extremely low-mass (ELM) white-dwarf (WD) stars are currently being found in the field of the Milky Way. Some of these stars exhibit long-period nonradial $g$-mode pulsations, and constitute the class of ELMV pulsating WDs. In addition, several low-mass pre-WDs, which could be precursors of ELM WDs, have been observed to show short-period photometric variations likely due to nonradial $p$ modes and radial modes. They could constitute a new class of pulsating low-mass pre-WD stars, the pre-ELMV stars. Here, we present the recent results of a thorough theoretical study of the nonadiabatic pulsation properties of low-mass He-core WDs and pre-WDs on the basis of fully evolutionary models representative of these stars.

  3. University of Nebraska Medical Center Mass Spectrometry and Proteomics Core Facility

    OpenAIRE

    Ciborowski, P.; Wojtkiewicz, M.

    2011-01-01

    The UNMC Mass Spectrometry and Proteomics Core Facility offers a broad range of services, such as ESI and MALDI protein identification using Mascot and Sequest Algorithms, iTRAQ-based quantitative proteomics, MRM protein quantitation, phosphoproteomics profiling and molecular weight determination for proteins, peptides and small molecules. The facility is equipped with LTQ Orbitrap ETD, LTQ Velos, 4800 MALDI TOF-TOF, 4000 Q TRAP, all with supporting nano-LC systems. Although the majority of u...

  4. Core-dominance parameter, black hole mass and jet-disc connection in Fermi blazars

    OpenAIRE

    Chen, Y. Y.; Zhang, X.; Zhang, H. J.; X. L. Yu

    2015-01-01

    We study the relationship between jet power and accretion for Fermi and non-Fermi blazars, respectively. We also compare the relevant parameter between them. Our main results are as follows. (i) Fermi and non-Fermi blazars have significant difference in redshift, black hole mass, and broad line luminosity. (ii) Fermi blazars have higher average core-dominance parameter than non-Fermi blazars, which suggests that Fermi blazars have strong beaming effect. (iii) We find significant correlation b...

  5. Maximum mass of a hot neutron star with a quark core

    Institute of Scientific and Technical Information of China (English)

    Tayebeh Yazdizadeh; Gholam Hossein Bordbar

    2011-01-01

    We have considered a hot neutron star with a quark core, a mixed phase of quark-hadron matter, and a hadronic matter crust and have determined the equation of state of the hadronic phase and the quark phase. We have then found the equation of state of the mixed phase under the Gibbs conditions. Finally, we have computed the structure of a hot neutron star with a quark core and compared our results with those of the neutron star without a quark core. For the quark matter calculations, we have used the MIT bag model in which the total energy of the system is considered as the kinetic energy of the particles plus a bag constant. For the hadronic matter calculations, we have used the lowest order constrained variational formalism. Our calculations show that the results for the maximum gravitational mass of a hot neutron star with a quark core are substantially different from those of a neutron star without the quark core.

  6. Preliminary Multiphysics Analyses of HFIR LEU Fuel Conversion using COMSOL

    Energy Technology Data Exchange (ETDEWEB)

    Freels, James D [ORNL; Bodey, Isaac T [ORNL; Arimilli, Rao V [ORNL; Curtis, Franklin G [ORNL; Ekici, Kivanc [ORNL; Jain, Prashant K [ORNL

    2011-06-01

    4 of this report. The HFIR LEU conversion project has also obtained the services of Dr. Prashant K. Jain of the Reactor & Nuclear Systems Division (RNSD) of ORNL. Prashant has quickly adapted to the COMSOL tools and has been focusing on thermal-structure interaction (TSI) issues and development of alternative 3D model approaches that could yield faster-running solutions. Prashant is the primary contributor to Section 5 of the report. And finally, while incorporating findings from all members of the COMSOL team (i.e., the team) and contributing as the senior COMSOL leader and advocate, Dr. James D. Freels has focused on the 3D model development, cluster deployment, and has contributed primarily to Section 3 and overall integration of this report. The team has migrated to the current release of COMSOL at version 4.1 for all the work described in this report, except where stated otherwise. Just as in the performance of the research, each of the respective sections has been originally authored by the respective authors. Therefore, the reader will observe a contrast in writing style throughout this document.

  7. Central Mass Profiles of the Nearby Cool-core Galaxy Clusters Hydra A and A478

    CERN Document Server

    Okabe, N; Tamura, T; Fujita, Y; Takizawa, M; Matsushita, K; Fukazawa, Y; Futamase, T; Kawaharada, M; Miyazaki, S; Mochizuki, Y; Nakazawa, K; Ohashi, T; Ota, N; Sasaki, T; Sato, K; Tam, S I

    2015-01-01

    We perform a weak-lensing study of the nearby cool-core galaxy clusters, Hydra A ($z=0.0538$) and A478 ($z=0.0881$), of which brightest cluster galaxies (BCGs) host powerful activities of active galactic nuclei (AGNs). For each cluster, the observed tangential shear profile is well described either by a single Navarro--Frenk--White model or a two-component model including the BCG as an unresolved point mass. For A478, we determine the BCG and its host-halo masses from a joint fit to weak-lensing and stellar photometry measurements. We find that the choice of initial mass functions (IMFs) can introduce a factor of two uncertainty in the BCG mass, whereas the BCG host halo mass is well constrained by data. We perform a joint analysis of weak-lensing and stellar kinematics data available for the Hydra A cluster, which allows us to constrain the central mass profile without assuming specific IMFs.We find that the central mass profile ($r<300$ kpc) determined from the joint analysis is in excellent agreement wi...

  8. INTERMEDIATE-MASS HOT CORES AT {approx}500 AU: DISKS OR OUTFLOWS?

    Energy Technology Data Exchange (ETDEWEB)

    Palau, Aina; Girart, Josep M. [Institut de Ciencies de l' Espai (CSIC-IEEC), Campus UAB-Facultat de Ciencies, Torre C5-parell 2, 08193 Bellaterra, Catalunya (Spain); Fuente, Asuncion; Alonso-Albi, Tomas [Observatorio Astronomico Nacional, P.O. Box 112, 28803 Alcala de Henares, Madrid (Spain); Fontani, Francesco; Sanchez-Monge, Alvaro [Osservatorio Astrofisico di Arcetri, INAF, Largo E. Fermi 5, 50125 Firenze (Italy); Boissier, Jeremie [Istituto di Radioastronomia, INAF, Via Gobetti 101, Bologna (Italy); Pietu, Vincent; Neri, Roberto [IRAM, 300 Rue de la piscine, 38406 Saint Martin d' Heres (France); Busquet, Gemma [Istituto di Fisica dello Spazio Interplanetario, INAF, Area di Recerca di Tor Vergata, Via Fosso Cavaliere 100, 00133 Roma (Italy); Estalella, Robert [Departament d' Astronomia i Meteorologia (IEEC-UB), Institut Ciencies Cosmos, Universitat Barcelona, Marti Franques 1, 08028 Barcelona (Spain); Zapata, Luis A. [Centro de Radioastronomia y Astrofisica, Universidad Nacional Autonoma de Mexico, P.O. Box 3-72, 58090 Morelia, Michoacan (Mexico); Zhang, Qizhou; Ho, Paul T. P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Audard, Marc, E-mail: palau@ieec.uab.es [Geneva Observatory, University of Geneva, Ch. des Maillettes 51, 1290 Versoix (Switzerland)

    2011-12-20

    Observations with the Plateau de Bure Interferometer in the most extended configuration toward two intermediate-mass star-forming regions, IRAS 22198+6336 and AFGL 5142, reveal the presence of several complex organic molecules at {approx}500 AU scales, confirming the presence of hot cores in both regions. The hot cores are not rich in CN-bearing molecules, as often seen in massive hot cores, and are mainly traced by CH{sub 3}CH{sub 2}OH, (CH{sub 2}OH){sub 2}, CH{sub 3}COCH{sub 3}, and CH{sub 3}OH, with, additionally, CH{sub 3}CHO, CH{sub 3}OD, and HCOOD for IRAS 22198+6336, and C{sub 6}H and O{sup 13}CS for AFGL 5142. The emission of complex molecules is resolved down to sizes of {approx}300 and {approx}600 AU, for IRAS 22198+6336 and AFGL 5142, respectively, and most likely is tracing protostellar disks rather than flattened envelopes or toroids as is usually found. This is especially clear for the case of IRAS 22198+6336, where we detect a velocity gradient for all the mapped molecules perpendicular to the most chemically rich outflow of the region, yielding a dynamic mass {approx}> 4 M{sub Sun }. As for AFGL 5142, the hot core emission is resolved into two elongated cores separated {approx}1800 AU. A detailed comparison of the complex molecule peaks to the new CO (2-1) data and H{sub 2}O maser data from the literature suggests also that for AFGL 5142 the complex molecules are mainly associated with disks, except for a faint and extended molecular emission found to the west, which is possibly produced in the interface between one of the outflows and the dense surrounding gas.

  9. MINIMUM CORE MASSES FOR GIANT PLANET FORMATION WITH REALISTIC EQUATIONS OF STATE AND OPACITIES

    Energy Technology Data Exchange (ETDEWEB)

    Piso, Ana-Maria A.; Murray-Clay, Ruth A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Youdin, Andrew N., E-mail: apiso@cfa.harvard.edu [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)

    2015-02-20

    Giant planet formation by core accretion requires a core that is sufficiently massive to trigger runaway gas accretion in less than the typical lifetime of protoplanetary disks. We explore how the minimum required core mass, M {sub crit}, depends on a non-ideal equation of state (EOS) and on opacity changes due to grain growth across a range of stellocentric distances from 5-100 AU. This minimum M {sub crit} applies when planetesimal accretion does not substantially heat the atmosphere. Compared to an ideal gas polytrope, the inclusion of molecular hydrogen (H{sub 2}) dissociation and variable occupation of H{sub 2} rotational states increases M {sub crit}. Specifically, M {sub crit} increases by a factor of ∼2 if the H{sub 2} spin isomers, ortho- and parahydrogen, are in thermal equilibrium, and by a factor of ∼2-4 if the ortho-to-para ratio is fixed at 3:1. Lower opacities due to grain growth reduce M {sub crit}. For a standard disk model around a Solar mass star, we calculate M {sub crit} ∼ 8 M {sub ⊕} at 5 AU, decreasing to ∼5 M {sub ⊕} at 100 AU, for a realistic EOS with an equilibrium ortho-to-para ratio and for grain growth to centimeter-sizes. If grain coagulation is taken into account, M {sub crit} may further reduce by up to one order of magnitude. These results for the minimum critical core mass are useful for the interpretation of surveys that find exoplanets at a range of orbital distances.

  10. Central mass profiles of the nearby cool-core galaxy clusters Hydra A and A478

    Science.gov (United States)

    Okabe, N.; Umetsu, K.; Tamura, T.; Fujita, Y.; Takizawa, M.; Matsushita, K.; Fukazawa, Y.; Futamase, T.; Kawaharada, M.; Miyazaki, S.; Mochizuki, Y.; Nakazawa, K.; Ohashi, T.; Ota, N.; Sasaki, T.; Sato, K.; Tam, S. I.

    2016-03-01

    We perform a weak-lensing study of the nearby cool-core galaxy clusters, Hydra A (z = 0.0538) and A478 (z = 0.0881), of which the brightest cluster galaxies (BCGs) host the powerful activities of active galactic nuclei (AGNs). For each cluster, the observed tangential shear profile is described well by either a single Navarro-Frenk-White model or a two-component model including the BCG as an unresolved point mass. For A478, we determine the BCG and its host-halo masses from a joint fit to weak-lensing and stellar photometry measurements. We find that the choice of initial mass functions (IMFs) can introduce a factor of 2 uncertainty in the BCG mass, whereas the BCG host-halo mass is constrained well by data. We perform a joint analysis of the weak-lensing and stellar kinematics data available for the Hydra A cluster, which allows us to constrain the central mass profile without assuming specific IMFs. We find that the central mass profile (r < 300 kpc) determined from the joint analysis is in excellent agreement with those from independent measurements, including dynamical masses estimated from the cold gas disc component, X-ray hydrostatic total mass estimates, and the central stellar mass estimated with the Salpeter IMF. The observed dark matter fraction around the BCG for Hydra A is found to be smaller than those predicted by adiabatic contraction models, suggesting the importance of other physical processes, such as AGN feedback and/or dissipationless mergers.

  11. Constraints for the Progenitor Masses of 17 Historic Core-Collapse Supernovae

    CERN Document Server

    Williams, Benjamin F; Murphy, Jeremiah; Gilbert, Karoline; Dalcanton, Julianne J; Dolphin, Andrew E; Jennings, Zachary G

    2015-01-01

    Using resolved stellar photometry measured from archival HST imaging, we generate color-magnitude diagrams of the stars within 50 pc of the locations of historic core-collapse supernovae that took place in galaxies within 8 Mpc. We fit these color-magnitude distributions with stellar evolution models to determine the best-fit age distribution of the young population. We then translate these age distributions into probability distributions for the progenitor mass of each SNe. The measurements are anchored by the main-sequence stars surrounding the event, making them less sensitive to assumptions about binarity, post-main-sequence evolution, or circumstellar dust. We demonstrate that, in cases where the literature contains masses that have been measured from direct imaging, our measurements are consistent with (but less precise than) these measurements. Using this technique, we constrain the progenitor masses of 17 historic SNe, 11 of which have no previous estimates from direct imaging. Our measurements still ...

  12. CORE

    DEFF Research Database (Denmark)

    Krigslund, Jeppe; Hansen, Jonas; Hundebøll, Martin

    2013-01-01

    different flows. Instead of maintaining these approaches separate, we propose a protocol (CORE) that brings together these coding mechanisms. Our protocol uses random linear network coding (RLNC) for intra- session coding but allows nodes in the network to setup inter- session coding regions where flows...... intersect. Routes for unicast sessions are agnostic to other sessions and setup beforehand, CORE will then discover and exploit intersecting routes. Our approach allows the inter-session regions to leverage RLNC to compensate for losses or failures in the overhearing or transmitting process. Thus, we...... increase the benefits of XORing by exploiting the underlying RLNC structure of individual flows. This goes beyond providing additional reliability to each individual session and beyond exploiting coding opportunistically. Our numerical results show that CORE outperforms both forwarding and COPE...

  13. CORE

    DEFF Research Database (Denmark)

    Krigslund, Jeppe; Hansen, Jonas; Hundebøll, Martin

    2013-01-01

    different flows. Instead of maintaining these approaches separate, we propose a protocol (CORE) that brings together these coding mechanisms. Our protocol uses random linear network coding (RLNC) for intra- session coding but allows nodes in the network to setup inter- session coding regions where flows...... intersect. Routes for unicast sessions are agnostic to other sessions and setup beforehand, CORE will then discover and exploit intersecting routes. Our approach allows the inter-session regions to leverage RLNC to compensate for losses or failures in the overhearing or transmitting process. Thus, we...... increase the benefits of XORing by exploiting the underlying RLNC structure of individual flows. This goes beyond providing additional reliability to each individual session and beyond exploiting coding opportunistically. Our numerical results show that CORE outperforms both forwarding and COPE...

  14. Intermediate-mass hot cores at 500 AU: disks or outflows?

    CERN Document Server

    Palau, Aina; Girart, Josep M; Fontani, Francesco; Boissier, Jeremie; Pietu, Vincent; Sanchez-Monge, Alvaro; Busquet, Gemma; Estalella, Robert; Zapata, Luis A; Zhang, Qizhou; Neri, Roberto; Ho, Paul T P; Alonso-Albi, Tomas; Audard, Marc

    2011-01-01

    Observations with the Plateau de Bure Interferometer in the most extended configuration toward two intermediate-mass star-forming regions, IRAS22198+6336 and AFGL5142, reveal the presence of several complex organic molecules at ~500 AU scales, confirming the presence of hot cores in both regions. The hot cores are not rich in CN-bearing molecules, as often seen in massive hot cores, and are mainly traced by CH3CH2OH, (CH2OH)2, CH3COCH3, and CH3OH, with additionally CH3CHO, CH3OD and HCOOD for IRAS22198+6336, and C6H, and O13CS for AFGL5142. The emission of complex molecules is resolved down to sizes of ~300 and ~600 AU, for IRAS22198+6336 and AFGL5142, respectively, and most likely is tracing protostellar disks rather than flattened envelopes or toroids as usually found. This is specially clear for the case of IRAS22198+6336, where we detect a velocity gradient for all the mapped molecules perpendicular to the most chemically rich outflow of the region, yielding a dynamic mass >4 Msun. As for AFGL5142, the ho...

  15. Minimum Core Masses for Giant Planet Formation With Realistic Equations of State and Opacities

    CERN Document Server

    Piso, Ana-Maria A; Murray-Clay, Ruth A

    2014-01-01

    Giant planet formation by core accretion requires a core that is sufficiently massive to trigger runaway gas accretion in less that the typical lifetime of protoplanetary disks. We explore how the minimum required core mass, M_crit, depends on a non-ideal equation of state and on opacity changes due to grain growth, across a range of stellocentric distances from 5-100 AU. This minimum M_crit applies when planetesimal accretion does not substantially heat the atmosphere. Compared to an ideal gas polytrope, the inclusion of molecular hydrogen (H_2) dissociation and variable occupation of H_2 rotational states increases M_crit. Specifically, M_crit increases by a factor of ~2 if the H_2 spin isomers, ortho- and parahydrogen, are in thermal equilibrium, and by a factor of ~2-4 if the ortho-to-para ratio is fixed at 3:1. Lower opacities due to grain growth reduce M_crit. For a standard disk model around a Solar mass star, we calculate M_crit ~ 8 M_Earth at 5 AU, decreasing to ~5 M_Earth at 100 AU, for a realistic ...

  16. Constraints for the progenitor masses of 17 historic core-collapse supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Benjamin F.; Peterson, Skyler; Gilbert, Karoline; Dalcanton, Julianne J. [Department of Astronomy, Box 351580, University of Washington, Seattle, WA 98195 (United States); Murphy, Jeremiah [Department of Physics, Florida State University, Tallahassee, FL 32306 (United States); Dolphin, Andrew E. [Raytheon, 1151 E. Hermans Road, Tucson, AZ 85706 (United States); Jennings, Zachary G., E-mail: ben@astro.washington.edu, E-mail: peters8@uw.edu, E-mail: jd@astro.washington.edu, E-mail: jeremiah@physics.fsu.edu, E-mail: kgilbert@stsci.edu, E-mail: dolphin@raytheon.com, E-mail: zgjennin@ucsc.edu [University of California Observatories, Santa Cruz, CA 95064 (United States)

    2014-08-20

    Using resolved stellar photometry measured from archival Hubble Space Telescope imaging, we generate color-magnitude diagrams of the stars within 50 pc of the locations of historic core-collapse supernovae (SNe) that took place in galaxies within 8 Mpc. We fit these color-magnitude distributions with stellar evolution models to determine the best-fit age distribution of the young population. We then translate these age distributions into probability distributions for the progenitor mass of each SN. The measurements are anchored by the main-sequence stars surrounding the event, making them less sensitive to assumptions about binarity, post-main-sequence evolution, or circumstellar dust. We demonstrate that, in cases where the literature contains masses that have been measured from direct imaging, our measurements are consistent with (but less precise than) these measurements. Using this technique, we constrain the progenitor masses of 17 historic SNe, 11 of which have no previous estimates from direct imaging. Our measurements still allow the possibility that all SN progenitor masses are <20 M {sub ☉}. However, the large uncertainties for the highest-mass progenitors also allow the possibility of no upper-mass cutoff.

  17. Density Profiles in Molecular Cloud Cores Associated with High-Mass Star-Forming Regions

    CERN Document Server

    Pirogov, Lev E

    2009-01-01

    Radial density profiles for the sample of dense cores associated with high-mass star-forming regions from southern hemisphere have been derived using the data of observations in continuum at 250 GHz. Radial density profiles for the inner regions of 16 cores (at distances $\\la 0.2-0.8$ pc from the center) are close on average to the $\\rho\\propto r^{-\\alpha}$ dependence, where $\\alpha=1.6\\pm 0.3$. In the outer regions density drops steeper. An analysis with various hydrostatic models showed that the modified Bonnor-Ebert model, which describes turbulent sphere confined by external pressure, is preferable compared with the logotrope and polytrope models practically in all cases. With a help of the Bonnor-Ebert model, estimates of central density in a core, non-thermal velocity dispersion and core size are obtained. The comparison of central densities with the densities derived earlier from the CS modeling reveals differences in several cases. The reasons of such differences are probably connected with the presen...

  18. Swelling of F82H irradiated at 673 K up to 51 dpa in HFIR

    Energy Technology Data Exchange (ETDEWEB)

    Miwa, Y. E-mail: miway@popsvr.tokai.jaeri.go.jp; Wakai, E.; Shiba, K.; Hashimoto, N.; Robertson, J.P.; Rowcliffe, A.F.; Hishinuma, A

    2000-12-01

    Reduced-activation ferritic/martensitic steel, F82H (8Cr-2W-0.2V-0.04Ta-0.1C), and variants doped with isotopically tailored boron were irradiated at 673 K up to 51 dpa in the high flux isotope reactor (HFIR). The concentrations of {sup 10}B in these alloys were 4, 62, and 325 appm during HFIR irradiation which resulted in the production of 4, 62 and 325 appm He, respectively. After irradiation, transmission electron microscopy (TEM) was carried out. The number density of cavities increased and the average diameter of cavities decreased with increasing amounts of {sup 10}B. The number density decreased and the average diameter increased with increasing displacement damage. Swelling increased as a function of displacement damage and He concentration.

  19. Observations of Deuterated Species toward Low-Mass Prestellar and Protostellar Cores

    Science.gov (United States)

    Nishimura, Y.; Sakai, N.; Watanabe, Y.; Sakai, T.; Hirota, T.; Yamamoto, S.

    2013-10-01

    We have conducted observations of the ground-state transition lines (J = 1-0) of the fundamental deuterated species DCO+, DNC, DCN, CCD and N2D+ as well as those of H13CO+, HN13C, H13CN, CCH and N2H+ with the Nobeyama 45 m telescope. The target sources are the cold starless cores, TMC-1 and Lupus-1A, and the low-mass star forming cores, L1527 and IRAS15398-3359. The excitation temperatures derived from intensities of resolved hyperfine components are systematically different between DNC and HN13C. On the other hand, the excitation temperatures of DCN and H13CN are comparable to each other. Although the origin of these results is puzzling, the present result indicates that accurate evaluation of the excitation temperature is essential for deriving deuterium fractionation ratios accurately.

  20. 2D dynamics of the radiative core of low mass stars

    CERN Document Server

    Hypolite, Delphine; Rieutord, Michel

    2016-01-01

    Understanding the internal rotation of low mass stars all along their evolution is of primary interest when studying their rotational dynamics, internal mixing and magnetic field generation. In this context, helio- and asteroseismology probe angular velocity gradients deep within solar type stars at different evolutionary stages. Still the rotation close to the center of such stars on the main sequence is hardly detectable and the dynamical interaction of the radiative core with the surface convective envelope is not well understood. For instance, the influence of the differential rotation profile sustained by convection and applied as a boundary condition to the radiation zone is very important in the formation of tachoclines. In this work, we study a 2D hydrodynamical model of a radiative core when an imposed, solar or anti-solar, differential rotation is applied at the upper boundary. This model uses the Boussinesq approximation and we find that the shear induces a cylindrical differential rotation associa...

  1. Neutrino Mass Ordering Studies with PINGU and IceCube/DeepCore

    CERN Document Server

    Wren, Steven

    2016-01-01

    The Precision IceCube Next Generation Upgrade (PINGU) is a proposed extension to the IceCube detector. The design of PINGU would augment the existing 86 strings with an additional 40 with the main goal of determining the neutrino mass ordering (NMO). Preliminary studies of the NMO can start with IceCube/DeepCore, a sub-array of more densely- packed strings in operation since 2011. This detector has a neutrino energy threshold of roughly 10 GeV and allows for high-statistics datasets of atmospheric neutrinos to be collected. This data provides a unique opportunity to better understand the systematic effects involved in making the NMO measurement by comparing the simulation studies to real data. These proceedings will present the current status of these studies in Monte Carlo simulations with projected DeepCore sensitivity for the NMO.

  2. Dynamical Constraints on the Core Mass of Hot Jupiter HAT-P-13b

    CERN Document Server

    Buhler, Peter; Batygin, Konstantin; Fulton, BJ; Fortney, Jonathan; Burrows, Adam; Wong, Ian

    2016-01-01

    HAT-P-13b is a Jupiter-mass transiting exoplanet that has settled onto a stable, short-period, and mildly eccentric orbit as a consequence of the action of tidal dissipation and perturbations from a second, highly eccentric, outer companion. Due to the special orbital configuration of the HAT-P-13 system, the magnitude of HAT-P-13b's eccentricity ($e_b$) is in part dictated by its Love number ($k_{2_b}$), which is in turn a proxy for the degree of central mass concentration in its interior. Thus, the measurement of $e_b$ constrains $k_{2_b}$ and allows us to place otherwise elusive constraints on the mass of HAT-P-13b's core ($M_{\\rm{core,b}}$). In this study we derive new constraints on the value of $e_b$ by observing two secondary eclipses of HAT-P-13b with the Infrared Array Camera on board the $\\textit{Spitzer Space Telescope}$. We fit the measured secondary eclipse times simultaneously with radial velocity measurements and find that $e_b = 0.00700 \\pm 0.00100$. We then use octupole-order secular perturba...

  3. Neutron dosimetry and damage calculations for the HFIR-JP-23 irradiations

    Energy Technology Data Exchange (ETDEWEB)

    Greenwood, L.R.; Ratner, R.T. [Pacific Northwest National Lab., Richland, WA (United States)

    1997-04-01

    Neutron fluence measurements and radiation damage calculations are reported for the joint U.S. Japanese experiment JP-23, which was conducted in target position G6 of the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL). The maximum neutron fluence at midplanes was 4.4E+22 n/cm{sup 2} resulting in about 9.0 dpa in type 316 stainless steel.

  4. Study of in-reactor creep of vanadium alloy in the HFIR RB-12J experiment

    Energy Technology Data Exchange (ETDEWEB)

    Strain, R.V.; Konicek, C.F.; Tsai, H. [Argonne National Lab., IL (United States)

    1996-10-01

    Biaxial creep specimens will be included in the HFIR RB-12J experiment to study in-reactor creep of the V-4Cr-4Ti alloy at {approx}500{degrees}C and 5 dpa. These specimens were fabricated with the 500-kg, heat (832665) material and pressurized to attain 0, 50, 100, 150, and 200 MPa mid-wall hoop stresses during the irradiation.

  5. Neutron dosimetry and damage calculations for the HFIR-JP-23 irradiations

    Energy Technology Data Exchange (ETDEWEB)

    Greenwood, L.R.; Ratner, R.T. [Pacific Northwest National Lab., Richland, WA (United States)

    1996-10-01

    Neutron fluence measurements and radiation damage calculations are reported for the joint US-Japanese experiment JP-23, which was conducted in target position G6 of the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL). The maximum neutron fluence at midplane was 4.4E+22 n/cm{sup 2} resulting in about 9.0 dpa in type 316 stainless steel.

  6. Design of a creep experiment for SiC/SiC composites in HFIR

    Energy Technology Data Exchange (ETDEWEB)

    Hecht, S.L.; Hamilton, M.L.; Jones, R.H. [and others

    1997-08-01

    A new specimen was designed for performing in-reactor creep tests on composite materials, specifically on SiC/SiC composites. The design was tailored for irradiation at 800{degrees}C in a HFIR RB position. The specimen comprises a composite cylinder loaded by a pressurized internal bladder that is made of Nb1Zr. The experiment was designed for approximately a one year irradiation.

  7. Preliminary report on the irradiation conditions of the HFIR JP-23 experiment

    Energy Technology Data Exchange (ETDEWEB)

    Ermi, A.M. [Westinghouse Hanford Company, Richland, WA (United States); Gelles, D.S. [Pacific Northwest Laboratory, Richland, WA (United States)

    1995-04-01

    The objective of this effort was to irradiate a series of alloys over the temperature range 300 to 600{degrees}C to approximately 10 dpa in the High Flux Isotope Reactor (HFIR). The alloys covered a wide range of materials and treatments. The Japanese specimen matrix consisted of ferritic steels, vanadium alloys, copper alloys, molybdenum alloys, and titanium-aluminum compounds. The US specimen matrix consisted of vanadium alloys, 316 stainless steels, and isotopically tailored ferritic and austenitic alloys.

  8. Outflow Detection in a 70 μm Dark High-Mass Core

    Science.gov (United States)

    Feng, Siyi; Beuther, Henrik; Zhang, Qizhou; Liu, Hauyu Baobab; Zhang, Zhiyu; Wang, Ke; Qiu, Keping

    2016-09-01

    We present observations toward a high-mass (\\gt 40 {M}⊙ ), low-luminosity (\\lt 10 {L}⊙ ) 70 μ {{m}} dark molecular core G28.34 S-A at 3.4 mm, using the IRAM 30 m telescope and the NOEMA interferometer. We report the detection of {SiO} J=2\\to 1 line emission, which is spatially resolved in this source at a linear resolution of ˜0.1 pc, while the 3.4 mm continuum image does not resolve any internal sub-structures. The SiO emission exhibits two W-E oriented lobes centering on the continuum peak. Corresponding to the redshifted and blueshifted gas with velocities up to 40 {km} {{{s}}}-1 relative to the quiescent cloud, these lobes clearly indicate the presence of a strong bipolar outflow from this 70 μ {{m}} dark core, a source previously considered as one of the best candidates of “starless” core. Our SiO detection is consistent with ALMA archival data of {SiO} J=5\\to 4, whose high-velocity blueshifted gas reveals a more compact lobe spatially closer to the dust center. This outflow indicates that the central source may be in an early evolutionary stage of forming a high-mass protostar. We also find that the low-velocity components (in the range of {{Vlsr}}-5+3 {km} {{{s}}}-1) have an extended, NW-SE oriented distribution. Discussing the possible accretion scenarios of the outflow-powering young stellar object, we argue that molecular line emission and the molecular outflows may provide a better indication of the accretion history of the forming young stellar object, than snapshot observations of the present bolometric luminosity. This is particularly significant for cases of episodic accretion, which may occur during the collapse of the parent molecular core.

  9. Fracture toughness and Charpy impact properties of several RAFMS before and after irradiation in HFIR

    Energy Technology Data Exchange (ETDEWEB)

    Sokolov, M.A. [Oak Ridge National Laboratory, Oak Ridge, TN 37831-6151 (United States)]. E-mail: sokolovm@ornl.gov; Tanigawa, H. [Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Odette, G.R. [University of California-Santa Barbara, Santa Barbara, CA 93106-5080 (United States); Shiba, K. [Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Klueh, R.L. [Oak Ridge National Laboratory, Oak Ridge, TN 37831-6151 (United States)

    2007-08-01

    As part of the development of candidate reduced-activation ferritic steels for fusion applications, several steels, namely F82H, 9Cr-2WVTa steels and F82H weld metal, are being investigated in the joint DOE-JAEA collaboration program. Within this program, three capsules containing a variety of specimen designs were irradiated at two design temperatures in the ORNL High Flux Isotope Reactor (HFIR). Two capsules, RB-11J and RB-12J, were irradiated in the HFIR removable beryllium positions with europium oxide (Eu{sub 2}O{sub 3}) thermal neutron shields in place. Specimens were irradiated up to 5 dpa. Capsule JP25 was irradiated in the HFIR target position to 20 dpa. The design temperatures were 300 {sup o}C and 500 {sup o}C. Precracked third-sized V-notch Charpy (3.3 x 3.3 x 25.4 mm) and 0.18 T DC(T) specimens were tested to determine transition and ductile shelf fracture toughness before and after irradiation. The master curve methodology was applied to evaluate the fracture toughness transition temperature, T {sub 0}. Irradiation induced shifts of T {sub 0} and reductions of J {sub Q} were compared with Charpy V-notch impact properties. Fracture toughness and Charpy shifts were also compared to hardening results.

  10. Analysis of HFIR Dosimetry Experiments Performed in Cycles 400 and 401

    Energy Technology Data Exchange (ETDEWEB)

    Remec, Igor [ORNL; Baldwin, Charles A [ORNL

    2008-09-01

    The High Flux Isotope Reactor (HFIR) has been in operation at Oak Ridge National Laboratory since 1966. To upgrade and enhance capabilities for neutron science research at the reactor, a larger HB-2 beam tube was installed in April of 2002. To assess, experimentally, the impact of this larger beam tube on radiation damage rates [i.e., displacement-per-atom (dpa) rates] used in vessel life extension studies, dosimetry experiments were performed from April to August 2004 during fuel cycles 400 and 401. This report documents the analysis of the dosimetry experiments and the determination of best-estimate dpa rates. These dpa rates are obtained by performing a least-squares adjustment of calculated neutron and gamma-ray fluxes and the measured responses of radiometric monitors and beryllium helium accumulation fluence monitors. The best-estimate dpa rates provided here will be used to update HFIR pressure vessel life extension studies, which determine the pressure/temperature limits for reactor operation and the HFIR pressure vessel's remaining life. All irradiation parameters given in this report correspond to a reactor power of 85 MW.

  11. Operating and maintenance manual for the HFIR production model homogeneity scanner

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, J.W.; Shipp, R.L.; Sliski, T.F.; Longaker, W.H.; Klindt, K.K.

    1984-12-01

    The fuel material in a HFIR fuel is U/sub 3/O/sub 8/ dispersed in aluminum, resembling an airfoil in cross section. To ensure uniform generation of heat within the plate, all plates must be tested (nondestructively) to determine that the U/sub 3/O/sub 8/ content is within specified limits. The HFIR homogeneity scanner developed for this purpose is a density/thickness gauge that bombards a plate with a highly collimated, 0.062-in.-diam beam of x rays and detects those transmitted through the plate. Variations in the transmitted x rays due to absorption in the fuel plate are a measure of fuel denisty. In addition to the fuel plates for HFIR, fuel plates for several other reactors, such as the Oak Ridge Research Reactor (ORR) are also checked by the homogeneity scanner by using other sets of standards. All of the other reactors have a uniform cross section. This manual describes procedures for its electronic components.

  12. Accessible or Inaccessible? Diagnostic Efficacy of CT-Guided Core Biopsies of Head and Neck Masses

    Energy Technology Data Exchange (ETDEWEB)

    Cunningham, Jane D., E-mail: janecunningham0708@gmail.com; McCusker, Mark W.; Power, Sarah; PearlyTi, Joanna; Thornton, John; Brennan, Paul; Lee, Michael J.; O’Hare, Alan; Looby, Seamus [Beaumont Hospital, Department of Radiology (Ireland)

    2015-04-15

    PurposeTissue sampling of lesions in the head and neck is challenging due to complex regional anatomy and sometimes necessitates open surgical biopsy. However, many patients are poor surgical candidates due to comorbidity. Thus, we evaluated the use of CT guidance for establishing histopathological diagnosis of head and neck masses.MethodsAll consecutive patients (n = 22) who underwent CT-guided core biopsy of head or neck masses between April 2009 and August 2012 were retrospectively reviewed using the departmental CT interventional procedures database. The indication for each biopsy performed was to establish or exclude a diagnosis of neoplasia in patients with suspicious head or neck lesions found on clinical examination or imaging studies. Patients received conscious sedation and 18 G, semiautomated core needle biopsies were performed by experienced neuroradiologists using 16-slice multidetector row CT imaging guidance (Somatom Definition Siemens Medical Solutions, Germany). Histopathology results of each biopsy were analysed.ResultsSixteen of 22 biopsies that were performed (73 %) yielded a pathological diagnosis. Anatomic locations biopsied included: masticator (n = 7), parapharyngeal (n = 3), parotid (n = 3), carotid (n = 3), perivertebral (n = 3), pharyngeal (n = 2), and retropharyngeal (n = 1) spaces. Six biopsies (27 %) were nondiagnostic due to inadequate tissue sampling, particularly small biopsy sample size and failure to biopsy the true sampling site due to extensive necrosis. No major complications were encountered.ConclusionsThe use of CT guidance to perform core biopsies of head and neck masses is an effective means of establishing histopathological diagnosis and reduces the need for diagnostic open surgical biopsy and general anaesthesia.

  13. Diffusive convective overshoot in core He-burning intermediate mass stars. I: the LMC metallicity

    CERN Document Server

    Ventura, P; Straka, C W

    2005-01-01

    We present detailed evolutionary calculations focused on the evolution of intermediate mass stars with 3 Msun Msun. In terms of the theoretical interpretation of an open cluster stellar population, the differences introduced by the use of a self-consistent scheme for mixing in the core with adjacent exponential decay are relevant for ages in the range 80 Myr < t < 200 Myr. These results are robust, since they are insensitive to the choice of the free-parameters regulating the extension of the extra-mixing region.

  14. Axisymmetric Ab Initio Core-Collapse Supernova Simulations of 12--25 Solar Mass Stars

    Energy Technology Data Exchange (ETDEWEB)

    Bruenn, S. W. [Florida Atlantic University; Mezzacappa, Anthony [ORNL; Hix, William Raphael [ORNL; Lentz, E. J. [University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL); Messer, Bronson [ORNL; Lingerfelt, Eric J [ORNL; Blondin, J. M. [North Carolina State University; Endeve, Eirik [ORNL; Marronetti, Pedro [Florida Atlantic University; Yakunin, Konstantin [Florida Atlantic University

    2013-01-01

    We present an overview of four ab initio axisymmetric core-collapse supernova simulations employing detailed spectral neutrino transport computed with our CHIMERA code and initiated from Woosley & Heger (2007) progenitors of mass 12, 15, 20, and 25 M_sun. All four models exhibit shock revival over ~ 200 ms (leading to the possibility of explosion), driven by neutrino energy deposition. Hydrodynamic instabilities that impart substantial asymmetries to the shock aid these revivals, with convection appearing first in the 12 solar mass model and the standing accretion shock instability (SASI) appearing first in the 25 solar mass model. Three of the models have developed pronounced prolate morphologies (the 20 solar mass model has remained approximately spherical). By 500 ms after bounce the mean shock radii in all four models exceed 3,000 km and the diagnostic explosion energies are 0.33, 0.66, 0.65, and 0.70 Bethe (B=10^{51} ergs) for the 12, 15, 20, and 25 solar mass models, respectively, and are increasing. The three least massive of our models are already sufficiently energetic to completely unbind the envelopes of their progenitors (i.e., to explode), as evidenced by our best estimate of their explosion energies, which first become positive at 320, 380, and 440 ms after bounce. By 850 ms the 12 solar mass diagnostic explosion energy has saturated at 0.38 B, and our estimate for the final kinetic energy of the ejecta is ~ 0.3 B, which is comparable to observations for lower-mass progenitors.

  15. Mass-Radius Relations and Core-Envelope Decompositions of Super-Earths and Sub-Neptunes

    CERN Document Server

    Howe, Alex R; Verne, Wesley

    2014-01-01

    Many exoplanets have been discovered with radii of 1-4 Earth radii, between that of Earth and Neptune. A number of these are known to have densities consistent with solid compositions, while others are "sub-Neptunes" likely to have significant hydrogen-helium envelopes. Future surveys will no doubt significantly expand these populations. In order to understand how the measured masses and radii of such planets can inform their structures and compositions, we construct models both for solid layered planets and for planets with solid cores and gaseous envelopes, exploring a range of core masses, hydrogen-helium envelope masses, and associated envelope entropies. For planets in the super-Earth/sub-Neptune regime for which both radius and mass are measured, we estimate how each is partitioned into a solid core and gaseous envelope, associating a specific core mass and envelope mass with a given exoplanet. We perform this decomposition for both "Earth-like" rock-iron cores and pure ice cores, and find that the nece...

  16. Survival of a convective core in low-mass solar-like pulsator HD 203608

    CERN Document Server

    Deheuvels, S; Goupil, M J; Marques, J P; Mosser, B; Dupret, M A; Lebreton, Y; Pichon, B; Morel, P

    2010-01-01

    A 5-night asteroseismic observation of the F8V star HD 203608 was conducted in August 2006 with HARPS, followed by an analysis of the data, and a preliminary modeling of the star (Mosser et al. 2008). The stellar parameters were significantly constrained, but the behavior of one of the seismic indexes (the small spacing d01) could not be fitted with the observed one, even with the best considered models. We study the possibility of improving the agreement between models and observations by changing the physical properties of the inner parts of the star (to which d01 is sensitive). We show that, in spite of its low mass, it is possible to produce models of HD 203608 with a convective core. No such model was considered in the preliminary modeling. In practice, we obtain these models here by assuming some extra mixing at the edge of the early convective core. We optimize the model parameters using the Levenberg-Marquardt algorithm. The agreement between the new best model with a convective core and the observati...

  17. Growth of Jupiter: Enhancement of Core Accretion by a Voluminous Low-Mass Envelope

    CERN Document Server

    D'Angelo, Gennaro; Lissauer, Jack J; Bodenheimer, Peter

    2014-01-01

    We present calculations of the early stages of the formation of Jupiter via core nucleated accretion and gas capture. The core begins as a seed body of about 350 kilometers in radius and orbits in a swarm of planetesimals whose initial radii range from 15 meters to 50 kilometers. The evolution of the swarm accounts for growth and fragmentation, viscous and gravitational stirring, and for drag-assisted migration and velocity damping. During this evolution, less than 9% of the mass is in planetesimals smaller than 1 kilometer in radius; < ~25% is in planetesimals with radii between 1 and 10 kilometers; and < ~7% is in bodies with radii larger than 100 kilometers. Gas capture by the core substantially enhances the size-dependent cross-section of the planet for accretion of planetesimals. The calculation of dust opacity in the planet's envelope accounts for coagulation and sedimentation of dust particles released as planetesimals are ablated. The calculation is carried out at an orbital semi-major axis of 5...

  18. Galaxy and Mass Assembly (GAMA): survey diagnostics and core data release

    CERN Document Server

    Driver, S P; Kelvin, L S; Robotham, A S G; Liske, J; Norberg, P; Baldry, I K; Bamford, S P; Hopkins, A M; Loveday, J; Peacock, J A; Andrae, E; Bland-Hawthorn, J; Brough, S; Brown, M J I; Cameron, E; Ching, J H Y; Colless, M; Conselice, C J; Croom, S M; Cross, N J G; De Propris, R; Dye, S; Drinkwater, M J; Ellis, S; Graham, Alister W; Grootes, M W; Gunawardhana, M; Jones, D H; van Kampen, E; Maraston, C; Nichol, R C; Parkinson, H R; Phillipps, S; Pimbblet, K; Popescu, C C; Prescott, M; Roseboom, I G; Sadler, E M; Sansom, A E; Sharp, R G; Smith, D J B; Taylor, E; Thomas, D; Tuffs, R J; Wijesinghe, D; Dunne, L; Frenk, C S; Jarvis, M J; Madore, B F; Meyer, M J; Seibert, M; Staveley-Smith, L; Sutherland, W J; Warren, S J

    2010-01-01

    The Galaxy And Mass Assembly (GAMA) survey has been operating since February 2008 on the 3.9-m Anglo-Australian Telescope using the AAOmega fibre-fed spectrograph facility to acquire spectra with a resolution of R~1300 for 120,862 SDSS selected galaxies. The target catalogue constitutes three contiguous equatorial regions centred at 9h (G09), 12h (G12) and 14.5h (G15) each of 12 x 4 sq.deg to limiting fluxes of r < 19.4, r < 19.8, and r < 19.4 mag respectively (and additional limits at other wavelengths). Spectra and reliable redshifts have been acquired for over 98 per cent of the galaxies within these limits. Here we present the survey footprint, progression, data reduction, redshifting, re-redshifting, an assessment of data quality after 3 years, additional image analysis products (including ugrizYJHK photometry, Sersic profiles and photometric redshifts), observing mask, and construction of our core survey catalogue (GamaCore). From this we create three science ready catalogues: GamaCoreDR1 for p...

  19. Outflow detection in a 70 $\\mu$m dark high-mass core

    CERN Document Server

    Feng, S; Zhang, Q; Liu, H B; Zhang, Z; Wang, K; Qiu, K

    2016-01-01

    We present observations towards a high-mass ($\\rm >40\\,M_{\\odot}$), low luminosity ($\\rm <10\\,L_{\\odot}$) $\\rm 70\\,\\mu$m dark molecular core G 28.34 S-A at 3.4 mm, using the IRAM 30 m telescope and the NOEMA interferometer. We report the detection of $\\rm SiO$ $J=\\rm 2\\rightarrow1$ line emission, which is spatially resolved in this source at a linear resolution of $\\sim$0.1 pc, while the 3.4 mm continuum image does not resolve any internal sub-structures. The SiO emission exhibits two W-E oriented lobes centring on the continuum peak. Corresponding to the red-shifted and blue-shifted gas with velocities up to $\\rm 40\\,km\\,s^{-1}$ relative to the quiescent cloud, these lobes clearly indicate the presence of a strong bipolar outflow from this $\\rm 70\\,\\mu$m dark core, a source previously considered as one of the best candidates of "starless" core. Our SiO detection is consistent with ALMA archival data of $\\rm SiO$ $J=\\rm 5\\rightarrow4$, whose high-velocity blue-shifted gas reveals a more compact lobe spatia...

  20. Multiple low-turbulence starless cores associated with intermediate- to high-mass star formation

    CERN Document Server

    Beuther, Henrik

    2009-01-01

    To characterize the initial conditions for intermediate- to high-mass star formation, we observed two Infrared Dark Clouds (IRDCs) that remain absorption features up to 70mum wavelength, with the PdBI in the 3.23mm dust continuum as well as the N2H+(1--0) and 13CS(2-1) line emission. While IRDC19175-4 is clearly detected in the 3.23mm continuum, the second source in the field, IRDC19175-5, is only barely observable above the 3sigma continuum detection threshold. However, the N2H+(1-0) observations reveal 17 separate sub-sources in the vicinity of the two IRDCs. Most of them exhibit low levels of turbulence (dv \\leq 1km/s), indicating that the fragmentation process in these cores may be dominated by the interplay of thermal pressure and gravity, but not so much by turbulence. Combining the small line widths with the non-detection up to 70mum and the absence of other signs of star formation activity, most of these 17 cores with masses between sub-solar to ~10M_sun are likely still in a starless phase. Furthermo...

  1. A 17-billion-solar-mass black hole in a group galaxy with a diffuse core.

    Science.gov (United States)

    Thomas, Jens; Ma, Chung-Pei; McConnell, Nicholas J; Greene, Jenny E; Blakeslee, John P; Janish, Ryan

    2016-04-21

    Quasars are associated with and powered by the accretion of material onto massive black holes; the detection of highly luminous quasars with redshifts greater than z = 6 suggests that black holes of up to ten billion solar masses already existed 13 billion years ago. Two possible present-day 'dormant' descendants of this population of 'active' black holes have been found in the galaxies NGC 3842 and NGC 4889 at the centres of the Leo and Coma galaxy clusters, which together form the central region of the Great Wall--the largest local structure of galaxies. The most luminous quasars, however, are not confined to such high-density regions of the early Universe; yet dormant black holes of this high mass have not yet been found outside of modern-day rich clusters. Here we report observations of the stellar velocity distribution in the galaxy NGC 1600--a relatively isolated elliptical galaxy near the centre of a galaxy group at a distance of 64 megaparsecs from Earth. We use orbit superposition models to determine that the black hole at the centre of NGC 1600 has a mass of 17 billion solar masses. The spatial distribution of stars near the centre of NGC 1600 is rather diffuse. We find that the region of depleted stellar density in the cores of massive elliptical galaxies extends over the same radius as the gravitational sphere of influence of the central black holes, and interpret this as the dynamical imprint of the black holes.

  2. Mass-transfer properties of insulin on core-shell and fully porous stationary phases.

    Science.gov (United States)

    Lambert, Nándor; Kiss, Ibolya; Felinger, Attila

    2014-10-31

    The mass-transfer properties of three superficially-porous packing materials, with 2.6 and 3.6μm particle and 1.9, 2.6, and 3.2μm inner core diameter, respectively, were investigated and compared with those of fully porous packings with similar particle properties. Several sources of band spreading in the chromatographic bed have been identified and studied according to the general rate model of chromatography. Besides the axial dispersion in the stream of the mobile phase, and the external mass transfer resistance, the intraparticle diffusion was studied in depth. The first absolute and the second central moments of the peaks of human insulin, over a wide range of mobile phase velocities were measured and used for the calculation of the mass-transfer coefficients. The experimental data were also analyzed using the stochastic or molecular dynamic model of Giddings and Eyring. The dissimilarities of the mass-transfer observed in the different columns were identified and evaluated. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. A Young Planetary-Mass Object in the rho Oph Cloud Core

    CERN Document Server

    Marsh, Kenneth A; Plavchan, Peter

    2009-01-01

    We report the discovery of a young planetary-mass brown dwarf in the rho Oph cloud core. The object was identified as such with the aid of a 1.5-2.4 micron low-resolution spectrum obtained using the NIRC instrument on the Keck I telescope. Based on the COND model, the observed spectrum is consistent with a reddened (Av ~ 15-16) brown dwarf whose effective temperature is in the range 1200-1800 K. For an assumed age of 1 Myr, comparison with isochrones further constrains the temperature to ~ 1400 K and suggests a mass of ~ 2-3 Jupiter masses. The inferred temperature is suggestive of an early T spectral type, which is supported by spectral morphology consistent with weak methane absorption. Based on its inferred distance (~ 100 pc) and the presence of overlying visual absorption, it is very likely to be a rho Oph cluster member. In addition, given the estimated spectral type, it may be the youngest and least massive T dwarf found so far. Its existence suggests that the initial mass function for the rho Oph star...

  4. Proteomics Core

    Data.gov (United States)

    Federal Laboratory Consortium — Proteomics Core is the central resource for mass spectrometry based proteomics within the NHLBI. The Core staff help collaborators design proteomics experiments in a...

  5. Proteomics Core

    Data.gov (United States)

    Federal Laboratory Consortium — Proteomics Core is the central resource for mass spectrometry based proteomics within the NHLBI. The Core staff help collaborators design proteomics experiments in...

  6. Complex molecules in the hot core of the low-mass protostar NGC 1333 IRAS 4A

    NARCIS (Netherlands)

    Bottinelli, S; Ceccarelli, C; Lefloch, B; Williams, JP; Castets, A; Caux, E; Cazaux, S; Maret, S; Parise, B; Tielens, AGGM

    2004-01-01

    We report the detection of complex molecules (HCOOCH3, HCOOH, and CH3CN), signposts of a hot core like region, toward the low-mass Class 0 source NGC 1333 IRAS 4A. This is the second low-mass protostar in which such complex molecules have been searched for and reported, the other source being IRAS

  7. Accelerator Mass Spectrometric determination of radiocarbon in stratospheric CO2, retrieved from AirCore sampling.

    Science.gov (United States)

    Paul, Dipayan; Been, Henk A.; Chen, Huilin; Kivi, Rigel; Meijer, Harro A. J.

    2015-04-01

    In this decade, understanding the impact of human activities on climate is one of the key issues of discussion globally. The continuous rise in the concentration of greenhouse gases, e.g., CO2, CH4, etc. in the atmosphere, predominantly due to human activities, is alarming and requires continuous monitoring to understand the dynamics. Radiocarbon is an important atmospheric tracer and one of the many used in the understanding of the global carbon budget, which includes the greenhouse gases like CO2 and CH4. Measurement of 14C (or radiocarbon) in atmospheric CO2 generally requires collection of large air samples (few liters) from which CO2 is extracted and then the concentration of radiocarbon is determined. Currently, Accelerator Mass Spectrometry (AMS) is the most precise, reliable and widely used technique for atmospheric radiocarbon detection. However, the regular collection of air samples from troposphere and stratosphere, for example using aircraft, is prohibitively expensive. AirCore is an innovative atmospheric sampling system, developed by NOAA. It comprises of a long tube descending from a high altitude with one end open and the other closed, and has been demonstrated to be a reliable, cost-effective sampling system for high-altitude profile (up to ~ 30 km) measurements of CH4and CO2(Karion et al. 2010). In Europe, AirCore measurements are being performed on a regular basis near Sodankylä since September 2013. Here we describe the analysis of two such AirCore samples collected in July 2014, Finland, for determining the 14C concentration in stratospheric CO2. The two AirCore samples were collected on consecutive days. Each stratospheric AirCore sample was divided into six fractions, each containing ~ 35 μg CO2 (~9.5 μg C). Each fraction was separately trapped in 1 /4 inch coiled stainless steel tubing for radiocarbon measurements. The procedure for CO2 extraction from the stratospheric air samples; the sample preparation, with samples containing < 10

  8. 3D COMSOL Simulations for Thermal Deflection of HFIR Fuel Plate in the "Cheverton-Kelley" Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Jain, Prashant K [ORNL; Freels, James D [ORNL; Cook, David Howard [ORNL

    2012-08-01

    Three dimensional simulation capabilities are currently being developed at Oak Ridge National Laboratory using COMSOL Multiphysics, a finite element modeling software, to investigate thermal expansion of High Flux Isotope Reactor (HFIR) s low enriched uranium fuel plates. To validate simulations, 3D models have also been developed for the experimental setup used by Cheverton and Kelley in 1968 to investigate the buckling and thermal deflections of HFIR s highly enriched uranium fuel plates. Results for several simulations are presented in this report, and comparisons with the experimental data are provided when data are available. A close agreement between the simulation results and experimental findings demonstrates that the COMSOL simulations are able to capture the thermal expansion physics accurately and that COMSOL could be deployed as a predictive tool for more advanced computations at realistic HFIR conditions to study temperature-induced fuel plate deflection behavior.

  9. The Monbusho/US shielded HFIR irradiation experiment: HFIR-MFE-RB-11J and 12J (P3-3)

    Energy Technology Data Exchange (ETDEWEB)

    Grossbeck, M.L.; Lenox, K.E.; Janney, M.A. [Oak Ridge National Lab., TN (United States)] [and others

    1997-08-01

    This experiment is a joint project between the Japanese Monbushu, the Japan Atomic Energy Research Institute, and the U.S. Fusion Energy Sciences Program. It is the first of a series of experiments using europium oxide as a thermal neutron shield to minimize transmutations in vanadium alloys and ferritic/martensitic steels. The europium oxide shields were developed using ceramic processing techniques culminating in cold pressing and sintering. This experiment, which is a prototype for future fast neutron experiments in the HFIR, contains approximately 3200 specimens of 18 different types. The experiment began operating at 300 and 500{degrees}C in February 1997 and is projected to attain its goal fluence of {approximately} 5 dpa in February 1998.

  10. Surface water mass composition changes captured by cores of Arctic land-fast sea ice

    Science.gov (United States)

    Smith, I. J.; Eicken, H.; Mahoney, A. R.; Van Hale, R.; Gough, A. J.; Fukamachi, Y.; Jones, J.

    2016-04-01

    In the Arctic, land-fast sea ice growth can be influenced by fresher water from rivers and residual summer melt. This paper examines a method to reconstruct changes in water masses using oxygen isotope measurements of sea ice cores. To determine changes in sea water isotope composition over the course of the ice growth period, the output of a sea ice thermodynamic model (driven with reanalysis data, observations of snow depth, and freeze-up dates) is used along with sea ice oxygen isotope measurements and an isotopic fractionation model. Direct measurements of sea ice growth rates are used to validate the output of the sea ice growth model. It is shown that for sea ice formed during the 2011/2012 ice growth season at Barrow, Alaska, large changes in isotopic composition of the ocean waters were captured by the sea ice isotopic composition. Salinity anomalies in the ocean were also tracked by moored instruments. These data indicate episodic advection of meteoric water, having both lower salinity and lower oxygen isotopic composition, during the winter sea ice growth season. Such advection of meteoric water during winter is surprising, as no surface meltwater and no local river discharge should be occurring at this time of year in that area. How accurately changes in water masses as indicated by oxygen isotope composition can be reconstructed using oxygen isotope analysis of sea ice cores is addressed, along with methods/strategies that could be used to further optimize the results. The method described will be useful for winter detection of meteoric water presence in Arctic fast ice regions, which is important for climate studies in a rapidly changing Arctic. Land-fast sea ice effective fractionation coefficients were derived, with a range of +1.82‰ to +2.52‰. Those derived effective fractionation coefficients will be useful for future water mass component proportion calculations. In particular, the equations given can be used to inform choices made when

  11. Status of U.S./Japan collaborative program phase II HFIR target and RB{sup *} capsules

    Energy Technology Data Exchange (ETDEWEB)

    Pawel, J.E.; Lenox, K.E.; Longest, A.W. [Oak Ridge National Laboratory, TN (United States)] [and others

    1995-04-01

    The objective of the HFIR irradiations is to determine the response of various U.S. and Japanese austenitic and ferritic steels with different pretreatments and alloy compositions to the combined effects of displacement damage and helium generation. Specimen temperatures during irradiation range from 60 to 600{degrees}C and fluences range up to 60 dpa. The RB{sup *} experiments are a continuation of the ORR spectrally tailored experiments in which the spectrum is modified with a hafnium shield to simulate the expected fusion helium to damage (He/dpa) ratio. In the HFIR target capsules, many specimens have been isotopically tailored in order to achieve fusion helium generation rates.

  12. Transmutation-induced embrittlement of V-Ti-Ni and V-Ni alloys in HFIR

    Energy Technology Data Exchange (ETDEWEB)

    Ohnuki, S.; Takahashi, H. [Hokkaido Univ., Sapparo (Japan); Garner, F.A. [Pacific Northwest National Laboratory, Richland, WA (United States); Pawel, J.E. [Oak Ridge National Laboratory, TN (United States)] [and others

    1996-04-01

    Vanadium, V-1Ni, V-10Ti and V-10Ti-1Ni (at %) were irradiated in HFIR to doses ranging from 18 to 30 dpa and temperatures between 300 and 600C. Since the irradiation was conducted in a highly thermalized neutron spectrum without shielding against thermal neutrons, significant levels of chromium (15-22%) were formed by transmutation. The addition of such large chromium levels strongly elevated the ductile to brittle transition temperature. At higher irradiation temperatures radiation-induced segregation of transmutant Cr and solute Ti at specimen surfaces leads to strong increases in the density of the alloy.

  13. Calculated irradiation response of materials using fission reactor (HFIR, ORR, and EBR-II) neutron spectra

    Energy Technology Data Exchange (ETDEWEB)

    Gabriel, T.A.; Bishop, B.L.; Wiffen, F.W.

    1979-08-01

    In order to plan radiation damage experiments in fission reactors keyed toward fusion reactor applications, it is necessary to have available for these facilities displacement per atom (dpa) and gas production rates for many potential materials. This report supplies such data for the elemental constituents of alloys of interest to the United States fusion reactor alloy development program. The calculations are presented for positions of interest in the HFIR, ORR, and EBR-II reactors. DPA and gas production rates in alloys of interest can be synthesized from these results.

  14. Neutron dosimetry and damage calculations for the HFIR-JP-20 irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Greenwood, L.R. [Pacific Northwest National Lab., Richland, WA (United States); Baldwin, C.A. [Oak Ridge National Lab., TN (United States)

    1998-03-01

    Neutron fluence measurements and radiation damage calculations are reported for the joint US-Japanese experiment JP-20, which was conducted in a target position of the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL). The maximum total neutron fluence at midplane was 4.2 {times} 10{sup 22} n/cm{sup 2} (1.0 {times} 10{sup 22} n/cm{sup 2} above 0.1 MeV), resulting in about 8.4 dpa and 388 appm helium in type 316 stainless steel.

  15. Neutron dosimetry and damage calculations for the HFIR-JP-9, -12, and -15 irradiations

    Energy Technology Data Exchange (ETDEWEB)

    Greenwood, L.R. [Pacific Northwest National Lab., Richland, WA (United States); Baldwin, C.A. [Oak Ridge National Lab., TN (United States)

    1998-03-01

    Neutron fluence measurements and radiation damage calculations are reported for the joint US-Japanese experiments JP-9, -12, and -15. These experiments were conducted in target positions of the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) for a period of nearly four years. The maximum neutron fluence at midplane was 2.6 {times} 10{sup 23} n/cm{sup 2} (7.1 {times} 10{sup 22} n/cm{sup 2} above 0.1 MeV), resulting in about 60 dpa and 3900 appm helium in type 316 stainless steel.

  16. Neutron dosimetry and damage calculations for the HFIR-MFE-200J-1 irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Greenwood, L.R. [Pacific Northwest National Lab., Richland, WA (United States); Baldwin, C.A. [Oak Ridge National Lab., TN (United States)

    1998-03-01

    Neutron fluence measurements and radiation damage calculations are reported for the joint US-Japanese experiment MFE-200-J-, which was conducted in the removable beryllium (RB) position of the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL). The maximum neutron fluence at midplane was 4.1 {times} 10{sup 22} n/cm{sup 2} (1.9 {times} 10{sup 22} n/cm{sup 2} above 0.1 MeV), resulting in about 12 dpa and 28 appm helium in type 316 stainless steel.

  17. Neutron dosimetry and damage calculation for the JP-10, 11, 13, and 16 experiments in HFIR

    Energy Technology Data Exchange (ETDEWEB)

    Greenwood, L.R.; Ratner, R.T.

    1996-04-01

    Neutron fluence measurements and radiation damage calculations are reported for the joint U.S./Japanese experiments JP-10, 11, 13, and 16 in the target of the High Flux Isotope Reactor (HFIR) at Oak Ridge National Lab (ORNL). These experiments were irradiated at 85 MW for 238.5 EFPD. The maximum fast neutron fluence >0.1 MeV was about 2.1E + 22 n/cm{sup 2} for all of the experiments resulting in about 17.3 dpa in 316 stainless steel.

  18. Neutron dosimetry and damage calculations for the JP-17, 18 and 19 experiments in HFIR

    Energy Technology Data Exchange (ETDEWEB)

    Greenwood, L.R.; Baldwin, C.A.

    1996-04-01

    Neutron fluence measurements and radiation damage calculations are reported for the joint US-Japanese experiments JP-17, 18, and 19 in the target of the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL). These experiments were irradiated at 85 MW for two cycles resulting in 43.55 EFPD for JP-17 and 42.06 EFPD for JP-18 and 19. The maximum fast neutron fluence > 0.1 MeV was about 3.7E + 21 n/cm{sup 2} for all three irradiations, resulting in about 3 dpa in 316 stainless steel.

  19. A comparison of fine-needle aspiration, core biopsy, and surgical biopsy in the diagnosis of extremity soft tissue masses.

    Science.gov (United States)

    Kasraeian, Sina; Allison, Daniel C; Ahlmann, Elke R; Fedenko, Alexander N; Menendez, Lawrence R

    2010-11-01

    Biopsy tissue can be obtained through a fine needle, a wider coring needle, or through an open surgical incision. Though much literature exists regarding the diagnostic yield of these techniques individually, none compare accuracy of diagnosis in the same mass. We asked how the diagnostic accuracy of fine-needle aspiration, core biopsy, and open surgical biopsy compare in regard to identifying malignancy, establishing the exact diagnosis, and guiding the appropriate treatment of soft tissue masses. We prospectively studied 57 patients with palpable extremity soft tissue masses, performing fine-needle aspiration, followed by core biopsy, followed by surgical biopsy of the same mass. Open surgical biopsy was 100% accurate on all accounts. With regard to determining malignancy, fine-needle aspiration and core biopsy had 79.17% and 79.2% sensitivity, 72.7% and 81.8% specificity, 67.9% and 76% positive predictive value, 82.8% and 84.4% negative predictive value, and an overall accuracy of 75.4% and 80.7%, respectively. In regard to determining exact diagnosis, fine-needle aspiration had a 33.3% accuracy and core biopsy had a 45.6% accuracy. With regard to eventual treatment, fine-needle aspiration was 38.6% accurate and core biopsy was 49.1% accurate. In soft tissue mass diagnosis, core biopsy is more accurate than fine-needle aspiration on all accounts, and open biopsy is more accurate than both in determining malignancy, establishing the exact diagnosis, and the guiding appropriate treatment.

  20. Biased total mass of cool core galaxy clusters by Sunyaev-Zel'dovich Effect measurements

    CERN Document Server

    Conte, A; Comis, B; Lamagna, L; De Gregori, S

    2010-01-01

    The Sunyaev Zel'dovich (SZ) effect is one of the most powerful cosmological tools to investigate the large-scale Universe, in which clusters of galaxies are the most interesting target. The great advantage of the SZ effect of being redshift independent, in contrast with visible and X-ray observations, allows to directly estimate cluster total mass from the integrated comptonization parameter Y, even for faraway clusters. However, the lack of a complete knowledge of the Intra-Cluster gas (ICg) physics can affect the results. Taking into account self-similar temperature and density profiles of the ICg, we study how different ICg morphologies can affect the cluster total mass estimation. Due to the large percentage of cool core (CC) clusters, we analyze this class starting with a limited sample of eight objects, observed by Chandra. We simulate SZ observations of these clusters through X-ray derived information, and re-analyze the mock SZ data with the simplistic assumption for the ICg of an isothermal beta mode...

  1. Low-mass protostars and dense cores in different evolutionary stages in IRAS 00213+6530

    CERN Document Server

    Busquet, G; Estalella, R; Girart, J M; Anglada, G; Sepúlveda, I

    2009-01-01

    We aim at studying with high angular resolution a dense core associated with a low-luminosity IRAS source, IRAS 00213+6530, in order to investigate whether low mass star formation is really taking place in isolation. We performed observations at 1.2mm with the IRAM 30m telescope, VLA observations at 6cm, 3.6cm, 1.3cm, 7mm, and H2O maser and NH3 lines, and observations with the NASA 70m antenna in CCS and H2O maser. The cm and mm continuum emission, together with the near infrared data from the 2MASS allowed us to identify 3 YSOs, IRS1, VLA8A, and VLA8B, with different radio and infrared properties, and which seem to be in different evolutionary stages. The NH3 emission consists of three clouds. Two of these, MM1 and MM2, are associated with dust emission, while the southern cloud is only detected in NH3. The YSOs are embedded in MM1, where we found evidence of line broadening and temperature enhancements. On the other hand, the southern cloud and MM2 appear to be quiescent and starless. We modeled the radial ...

  2. Mass Fluxes Attending the Palagonitization of Sideromelane in Hyaloclastites From the HSDP-2 Core Hole

    Science.gov (United States)

    Walton, A.; Schiffman, P.; Macpherson, G. L.; Santee, S.

    2001-12-01

    Isovolumetric conversion of sideromelane to gel palagonitized glass releases components to solution because the latter is hydrated and less dense. In hyaloclastites from the HSDP-2 core, development of gel palagonitized glass is accompanied by the precipitation of secondary minerals, chiefly smectite, phillipsite, and chabazite, but also thaumasite, apophyllite, gyrolite, and gypsum. We have calculated mass balance among these major phases using a combination of electron microprobe analyses (for major elements) and laser ablation microprobe-inductively coupled mass spectrometry (for trace elements), in conjunction with density determinations and petrographic point counts. Our reconnaissance data indicate that most major elements are elutriated from sideromelane during conversion to gel palagonitized glass, except FeO which remains constant, and TiO2 which is somewhat enriched (by more than passive accumulation) in the gel palagonitized glass. Conversely, precipitation of secondary cements in pores requires addition of major elements to the whole rock, chiefly SiO2, Al2O3, K2O, MgO, and MnO. One unexpected initial result is that the REE patterns of sideromelane and associated gel palagonitized glasses are nearly identical. Differences in absolute abundances reflect change in density.

  3. The Formation of Free-Floating Brown Dwarves and Planetary-Mass Objects by Photo-Erosion of Prestellar Cores

    CERN Document Server

    Whitworth, A P

    2004-01-01

    We explore the possibility that, in the vicinity of an OB star, a prestellar core which would otherwise have formed an intermediate or low-mass star may form a free-floating brown dwarf or planetary-mass object, because the outer layers of the core are eroded by the ionizing radiation from the OB star before they can accrete onto the protostar at the centre of the core. The masses of objects formed in this way are given approximately by $\\sim 0.010 M_\\odot (a_{\\rm I} / 0.3 {\\rm km} {\\rm s}^{-1})^6 (\\dot{\\cal N}_{\\rm Lyc} / 10^{50} {\\rm s}^{-1})^{-1/3} (n_{\\rm 0} / 10^3 {\\rm cm}^{-3})^{-1/3} $, where $a_{\\rm I}$ is the isothermal sound speed in the neutral gas of the core, $\\dot{\\cal N}_{\\rm Lyc}$ is the rate of emission of Lyman continuum photons from the OB star (or stars), and $n_{\\rm 0}$ is the number-density of protons in the HII region surrounding the core. We conclude that the formation of low-mass objects by this mechanism should be quite routine, because the mechanism operates over a wide range of con...

  4. Comparison of Histologic Core Portions Acquired from a Core Biopsy Needle and a Conventional Needle in Solid Mass Lesions: A Prospective Randomized Trial.

    Science.gov (United States)

    Lee, Ban Seok; Cho, Chang-Min; Jung, Min Kyu; Jang, Jung Sik; Bae, Han Ik

    2017-07-15

    The superiority of endoscopic ultrasound-guided fine needle biopsy (EUS-FNB) over EUS-guided fine needle aspiration (EUS-FNA) remains controversial. Given the lack of studies analyzing histologic specimens acquired from EUS-FNB or EUS-FNA, we compared the proportion of the histologic core obtained from both techniques. A total of 58 consecutive patients with solid mass lesions were enrolled and randomly assigned to the EUS-FNA or EUS-FNB groups. The opposite needle was used after the failure of core tissue acquisition using the initial needle with up to three passes. Using computerized analyses of the scanned histologic slide, the overall area and the area of the histologic core portion in specimens obtained by the two techniques were compared. No significant differences were identified between the two groups with respect to demographic and clinical characteristics. Fewer needle passes were required to obtain core specimens in the FNB group (pcore (11.8%±19.5% vs 8.0%±11.1%, p=0.376) or in the diagnostic accuracy (80.6% vs 81.5%, p=0.935) between two groups. The proportion of histologic core and the diagnostic accuracy were comparable between the FNB and FNA groups. However, fewer needle passes were required to establish an accurate diagnosis in EUS-FNB.

  5. DNC/HNC and N2D+/N2H+ ratios in high-mass star-forming cores

    Science.gov (United States)

    Fontani, F.; Sakai, T.; Furuya, K.; Sakai, N.; Aikawa, Y.; Yamamoto, S.

    2014-05-01

    Chemical models predict that the deuterated fraction (the column density ratio between a molecule containing D and its counterpart containing H) of N2H+, Dfrac(N2H+), high in massive pre-protostellar cores, is expected to rapidly drop by an order of magnitude after the protostar birth, while that of HNC, Dfrac(HNC), remains constant for much longer. We tested these predictions by deriving Dfrac(HNC) in 22 high-mass star-forming cores divided in three different evolutionary stages, from high-mass starless core candidates (HMSCs, eight) to high-mass protostellar objects (HMPOs, seven) to ultracompact H II regions (UCHIIs, seven). For all of them, Dfrac(N2H+) was already determined through IRAM 30 m Telescope observations, which confirmed the theoretical rapid decrease of Dfrac(N2H+) after protostar birth. Therefore, our comparative study is not affected by biases introduced by the source selection. We have found average Dfrac(HNC) of 0.012, 0.009 and 0.008 in HMSCs, HMPOs and UCHIIs, respectively, with no statistically significant differences among the three evolutionary groups. These findings confirm the predictions of the chemical models, and indicate that large values of Dfrac(N2H+) are more suitable than large values of Dfrac(HNC) to identify cores on the verge of forming high-mass stars, likewise what was found in the low-mass regime.

  6. Calculation of RABBIT and Simulator Worth in the HFIR Hydraulic Tube and Comparison with Measured Values

    Energy Technology Data Exchange (ETDEWEB)

    Slater, CO

    2005-09-08

    To aid in the determinations of reactivity worths for target materials in a proposed High Flux Isotope Reactor (HFIR) target configuration containing two additional hydraulic tubes, the worths of cadmium rabbits within the current hydraulic tube were calculated using a reference model of the HFIR and the MCNP5 computer code. The worths were compared to measured worths for both static and ejection experiments. After accounting for uncertainties in the calculations and the measurements, excellent agreement between the two was obtained. Computational and measurement limitations indicate that accurate estimation of worth is only possible when the worth exceeds 10 cents. Results indicate that MCNP5 and the reactor model can be used to predict reactivity worths of various samples when the expected perturbations are greater than 10 cents. The level of agreement between calculation and experiment indicates that the accuracy of such predictions would be dependent solely on the quality of the nuclear data for the materials to be irradiated. Transients that are approximated by ''piecewise static'' computational models should likewise have an accuracy that is dependent solely on the quality of the nuclear data.

  7. Accelerated 54{degree}C irradiated test of Shippingport neutron shield tank and HFIR vessel materials

    Energy Technology Data Exchange (ETDEWEB)

    Hawthorne, J.R. [Materials Engineering Associates, Inc., Lanham, MD (United States); Rosinski, S.T. [Sandia National Labs., Albuquerque, NM (United States)

    1993-01-01

    Charpy V-notch specimens (ASTM Type A) and 5.74-mm diameter tension test specimens of the Shippingport Reactor Neutron Shield Tank (NST) (outer wall material) were irradiated together with Charpy V-notch specimens of the Oak Ridge National Laboratory (ORNI), High,, Flux Isotope Reactor (HFIR) vessel (shell material), to 5.07 {times} 10{sup 17} n/cm{sup 2}, E > 1 MeV. The irradiation was performed in the Ford Nuclear Reactor (FNR), a test reactor, at a controlled temperature of 54{degrees}C (130{degrees}F) selected to approximate the prior service temperatures of the cited reactor structures. Radiation-induced elevations in the Charpy 41-J transition temperature and the ambient temperature yield strength were small and independent of specimen test orientation (ASTM LT vs. TL). The observations are consistent with prior findings for the two materials (A 212-B plate) and other like materials irradiated at low temperature (< 200{degrees}C) to low fluence. The high radiation embrittlement sensitivity observed in HFIR vessel surveillance program tests was not found in the present accelerated irradiation test. Response to 288{degrees}C-168 h postirradiation annealing was explored for the NST material. Notch ductility recovery was found independent of specimen test orientation but dependent on the temperature within the transition region at which the specimens were tested.

  8. Accelerated 54[degree]C irradiated test of Shippingport neutron shield tank and HFIR vessel materials

    Energy Technology Data Exchange (ETDEWEB)

    Hawthorne, J.R. (Materials Engineering Associates, Inc., Lanham, MD (United States)); Rosinski, S.T. (Sandia National Labs., Albuquerque, NM (United States))

    1993-01-01

    Charpy V-notch specimens (ASTM Type A) and 5.74-mm diameter tension test specimens of the Shippingport Reactor Neutron Shield Tank (NST) (outer wall material) were irradiated together with Charpy V-notch specimens of the Oak Ridge National Laboratory (ORNI), High,, Flux Isotope Reactor (HFIR) vessel (shell material), to 5.07 [times] 10[sup 17] n/cm[sup 2], E > 1 MeV. The irradiation was performed in the Ford Nuclear Reactor (FNR), a test reactor, at a controlled temperature of 54[degrees]C (130[degrees]F) selected to approximate the prior service temperatures of the cited reactor structures. Radiation-induced elevations in the Charpy 41-J transition temperature and the ambient temperature yield strength were small and independent of specimen test orientation (ASTM LT vs. TL). The observations are consistent with prior findings for the two materials (A 212-B plate) and other like materials irradiated at low temperature (< 200[degrees]C) to low fluence. The high radiation embrittlement sensitivity observed in HFIR vessel surveillance program tests was not found in the present accelerated irradiation test. Response to 288[degrees]C-168 h postirradiation annealing was explored for the NST material. Notch ductility recovery was found independent of specimen test orientation but dependent on the temperature within the transition region at which the specimens were tested.

  9. DEUTERIUM BURNING IN MASSIVE GIANT PLANETS AND LOW-MASS BROWN DWARFS FORMED BY CORE-NUCLEATED ACCRETION

    Energy Technology Data Exchange (ETDEWEB)

    Bodenheimer, Peter [UCO/Lick Observatory, Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); D' Angelo, Gennaro; Lissauer, Jack J. [Space Science and Astrobiology Division, NASA-Ames Research Center, Moffett Field, CA 94035 (United States); Fortney, Jonathan J. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Saumon, Didier, E-mail: peter@ucolick.org, E-mail: gennaro.dangelo@nasa.gov, E-mail: Jack.J.Lissauer@nasa.gov, E-mail: jfortney@ucolick.org, E-mail: dsaumon@lanl.gov [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 (United States)

    2013-06-20

    Using detailed numerical simulations, we study the formation of bodies near the deuterium-burning limit according to the core-nucleated giant planet accretion scenario. The objects, with heavy-element cores in the range 5-30 M{sub Circled-Plus }, are assumed to accrete gas up to final masses of 10-15 Jupiter masses (M{sub Jup}). After the formation process, which lasts 1-5 Myr and which ends with a ''cold-start'', low-entropy configuration, the bodies evolve at constant mass up to an age of several Gyr. Deuterium burning via proton capture is included in the calculation, and we determined the mass, M{sub 50}, above which more than 50% of the initial deuterium is burned. This often-quoted borderline between giant planets and brown dwarfs is found to depend only slightly on parameters, such as core mass, stellar mass, formation location, solid surface density in the protoplanetary disk, disk viscosity, and dust opacity. The values for M{sub 50} fall in the range 11.6-13.6 M{sub Jup}, in agreement with previous determinations that do not take the formation process into account. For a given opacity law during the formation process, objects with higher core masses form more quickly. The result is higher entropy in the envelope at the completion of accretion, yielding lower values of M{sub 50}. For masses above M{sub 50}, during the deuterium-burning phase, objects expand and increase in luminosity by one to three orders of magnitude. Evolutionary tracks in the luminosity versus time diagram are compared with the observed position of the companion to Beta Pictoris.

  10. Preliminary Evaluation of Alternate Designs for HFIR Low-Enriched Uranium Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Renfro, David G [ORNL; Chandler, David [ORNL; Cook, David Howard [ORNL; Ilas, Germina [ORNL; Jain, Prashant K [ORNL; Valentine, Jennifer R [ORNL

    2014-11-01

    Engineering design studies of the feasibility of conversion of the High Flux Isotope Reactor (HFIR) from high-enriched uranium (HEU) to low-enriched uranium (LEU) fuel are ongoing at Oak Ridge National Laboratory (ORNL) as part of an effort sponsored by the U.S. Department of Energy s Global Threat Reduction Initiative (GTRI)/Reduced Enrichment for Research and Test Reactors (RERTR) program. The fuel type selected by the program for the conversion of the five high-power research reactors in the U.S. that still use HEU fuel is a new U-Mo monolithic fuel. Studies by ORNL have previously indicated that HFIR can be successfully converted using the new fuel provided (1) the reactor power can be increased from 85 MW to 100 MW and (2) the fuel can be fabricated to a specific reference design. Fabrication techniques for the new fuel are under development by the program but are still immature, especially for the complex aspects of the HFIR fuel design. In FY 2012, the program underwent a major shift in focus to emphasize developing and qualifying processes for the fabrication of reliable and affordable LEU fuel. In support of this new focus and in an effort to ensure that the HFIR fuel design is as suitable for reliable fabrication as possible, ORNL undertook the present study to propose and evaluate several alternative design features. These features include (1) eliminating the fuel zone axial contouring in the previous reference design by substituting a permanent neutron absorber in the lower unfueled region of all of the fuel plates, (2) relocating the burnable neutron absorber from the fuel plates of the inner fuel element to the side plates of the inner fuel element (the fuel plates of the outer fuel element do not contain a burnable absorber), (3) relocating the fuel zone inside the fuel plate to be centered on the centerline of the depth of the plate, and (4) reshaping the radial contour of the relocated fuel zone to be symmetric about this centerline. The present

  11. Preliminary Evaluation of Alternate Designs for HFIR Low-Enriched Uranium Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Renfro, David [ORNL; Chandler, David [ORNL; Cook, David [ORNL; Ilas, Germina [ORNL; Jain, Prashant [ORNL; Valentine, Jennifer [ORNL

    2014-10-30

    Engineering design studies of the feasibility of conversion of the High Flux Isotope Reactor (HFIR) from high-enriched uranium (HEU) to low-enriched uranium (LEU) fuel are ongoing at Oak Ridge National Laboratory (ORNL) as part of an effort sponsored by the U.S. Department of Energy’s Global Threat Reduction Initiative (GTRI)/Reduced Enrichment for Research and Test Reactors (RERTR) program. The fuel type selected by the program for the conversion of the five high-power research reactors in the U.S. that still use HEU fuel is a new U-Mo monolithic fuel. Studies by ORNL have previously indicated that HFIR can be successfully converted using the new fuel provided (1) the reactor power can be increased from 85 MW to 100 MW and (2) the fuel can be fabricated to a specific reference design. Fabrication techniques for the new fuel are under development by the program but are still immature, especially for the “complex” aspects of the HFIR fuel design. In FY 2012, the program underwent a major shift in focus to emphasize developing and qualifying processes for the fabrication of reliable and affordable LEU fuel. In support of this new focus and in an effort to ensure that the HFIR fuel design is as suitable for reliable fabrication as possible, ORNL undertook the present study to propose and evaluate several alternative design features. These features include (1) eliminating the fuel zone axial contouring in the previous reference design by substituting a permanent neutron absorber in the lower unfueled region of all of the fuel plates, (2) relocating the burnable neutron absorber from the fuel plates of the inner fuel element to the side plates of the inner fuel element (the fuel plates of the outer fuel element do not contain a burnable absorber), (3) relocating the fuel zone inside the fuel plate to be centered on the centerline of the depth of the plate, and (4) reshaping the radial contour of the relocated fuel zone to be symmetric about this centerline. The

  12. Deuterium Burning in Massive Giant Planets and Low-Mass Brown Dwarfs formed by Core-Nucleated Accretion

    CERN Document Server

    Bodenheimer, Peter; Lissauer, Jack J; Fortney, Jonathan J; Saumon, Didier

    2013-01-01

    Formation of bodies near the deuterium-burning limit is considered by detailed numerical simulations according to the core-nucleated giant planet accretion scenario. The objects, with heavy-element cores in the range 5-30 Mearth, are assumed to accrete gas up to final masses of 10-15 Jupiter masses (Mjup). After the formation process, which lasts 1-5 Myr and which ends with a 'cold-start', low-entropy configuration, the bodies evolve at constant mass up to an age of several Gyr. Deuterium burning via proton capture is included in the calculation, and we determined the mass, M50, above which more than 50% of the initial deuterium is burned. This often-quoted borderline between giant planets and brown dwarfs is found to depend only slightly on parameters, such as core mass, stellar mass, formation location, solid surface density in the protoplanetary disk, disk viscosity, and dust opacity. The values for M50 fall in the range 11.6-13.6 Mjup, in agreement with previous determinations that do not take the formati...

  13. The Role of Core Mass in Controlling Evaporation: the Kepler Radius Distribution and the Kepler-36 Density Dichotomy

    CERN Document Server

    Lopez, Eric

    2013-01-01

    We use models of coupled thermal evolution and photo-evaporative mass loss to understand the formation and evolution of the Kepler-36 system. We show that the large contrast in mean planetary density observed by Carter et al. (2012) can be explained as a natural consequence of photo-evaporation from planets that formed with similar initial compositions. However, rather than being due to differences in XUV irradiation between the planets, we find that this contrast is due to the difference in the masses of the planets' rock/iron cores and the impact that this has on mass loss evolution. We explore in detail how our coupled models depend on irradiation, mass, age, composition, and the efficiency of mass loss. Based on fits to large numbers of coupled evolution and mass loss runs, we provide analytic fits to understand threshold XUV fluxes for significant atmospheric loss, as a function of core mass and mass loss efficiency. Finally we discuss these results in the context of recent studies of the radius distribu...

  14. Body mass index is associated with biological CSF markers of core brain pathology of Alzheimer's disease.

    Science.gov (United States)

    Ewers, Michael; Schmitz, Susanne; Hansson, Oskar; Walsh, Cathal; Fitzpatrick, Annette; Bennett, David; Minthon, Lennart; Trojanowski, John Q; Shaw, Leslie M; Faluyi, Yetunde O; Vellas, Bruno; Dubois, Bruno; Blennow, Kaj; Buerger, Katharina; Teipel, Stefan J; Weiner, Michael; Hampel, Harald

    2012-08-01

    Weight changes are common in aging and Alzheimer's disease (AD) and postmortem findings suggest a relation between lower body mass index (BMI) and increased AD brain pathology. In the current multicenter study, we tested whether lower BMI is associated with higher core AD brain pathology as assessed by cerebrospinal fluid (CSF)-based biological markers of AD in 751 living subjects: 308 patients with AD, 296 subjects with amnestic mild cognitive impairment (MCI), and 147 elderly healthy controls (HC). Based upon a priori cutoff values on CSF concentration of total tau and beta-amyloid (Aβ(1-42)), subjects were binarized into a group with abnormal CSF biomarker signature (CSF+) and those without (CSF-). Results showed that BMI was significantly lower in the CSF+ when compared with the CSF- group (F = 27.7, df = 746, p < 0.001). There was no interaction between CSF signature and diagnosis or apolipoprotein E (ApoE) genotype. In conclusion, lower BMI is indicative of AD pathology as assessed with CSF-based biomarkers in demented and nondemented elderly subjects.

  15. Mass balance attending gel palagonitization of hyaloclastites in the HSDP 2 Phase 1 core

    Science.gov (United States)

    Walton, A. W.; Schiffman, P.; MacPherson, G.

    2002-12-01

    In the HSDP 2 core, the alteration of hyaloclastites is multi-episodic, but the predominant, "normal" alteration process - recorded in samples from depths between 1573 m and the bottom of the hole at over 3000 m - entails the conversion of rinds of sideromelane-rich shards to gel palagonite and growth of pore-filling chabazite. This reaction must occur relatively rapidly, because point-count porosity in the zone of normal alteration approaches zero within 200 m of the top of this zone and remains very low to the deepest samples. Furthermore, thickness of palagonite rinds does not increase down hole. Using modes from point counts on thin sections, major element analyses by electron microprobe, and trace element analyses by LAM-ICPMS, we have modeled the elemental mass balance for the normal palagonitization process in the HSDP hyaloclastites. Petrographic evidence suggests that this reaction does not involve solids other than sideromelane, gel palagonite, and chabazite and that the conversion of sideromelane to gel palagonite is isovolumetric. We used literature values of density: 2.80 g/cc for sideromelane, 2.00 for gel palagonite, and 2.075 for chabazite. The major elemental balance calculated for these conditions, and averaged over 10 samples shows net addition of K2O (by 17%), TiO2 (19%), and water, with net losses of MgO (73%), P2O5 (52%), MnO (29%), CaO (17%), Na2O (36%), SiO2 (19%), FeO (15%), and Al2O3 (18%). Individual samples show similar patterns. Decreasing the gel palagonite density (to 1.9 g/cc) and allowing for a 5% volume decrease reduces the TiO2 uptake (to 8%), but also increases the apparent loss of other "immobile" elements (FeO to 23% and Al2O3 to 22%). Normalized REE patterns for sideromelane versus gel palagonite show no systematic fractionations, although the normal reaction requires net gains on the order of 10-20% for most REEs. HFS elements are enriched in gel palagonite, relative to values in sideromelane, but LIL elements are depleted

  16. TWO MASS DISTRIBUTIONS IN THE L 1641 MOLECULAR CLOUDS: THE HERSCHEL CONNECTION OF DENSE CORES AND FILAMENTS IN ORION A

    Energy Technology Data Exchange (ETDEWEB)

    Polychroni, D. [Department of Astrophysics, University of Athens, Astronomy and Mechanics, Faculty of Physics, Panepistimiopolis, 15784 Zografos, Athens (Greece); Schisano, E.; Elia, D.; Molinari, S.; Turrini, D.; Rygl, K. L. J.; Benedettini, M.; Busquet, G.; Di Giorgio, A. M.; Pestalozzi, M.; Pezzuto, S. [Istituto di Astrofisica e Planetologia Spaziali (INAF-IAPS), via del Fosso del Cavaliere 100, I-00133 Roma (Italy); Roy, A.; André, Ph.; Hennemann, M.; Hill, T.; Könyves, V. [Laboratoire AIM, CEA/IRFU CNRS/INSU Université Paris Diderot, Paris-Saclay, F-91191 Gif-sur-Yvette (France); Martin, P. [Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George Street, Toronto, ON M5S 3H8 (Canada); Di Francesco, J. [National Research Council Canada, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada); Arzoumanian, D. [IAS, CNRS (UMR 8617), Université Paris-Sud, Bâtiment 121, F-91400 Orsay (France); Bontemps, S., E-mail: dpolychroni@phys.uoa.gr [Université de Bordeaux, Laboratoire d' Astrophysique de Bordeaux, CNRS/INSU, UMR 5804, BP 89, F-33271, Floirac Cedex (France); and others

    2013-11-10

    We present Herschel survey maps of the L 1641 molecular clouds in Orion A. We extracted both the filaments and dense cores in the region. We identified which of the dense sources are proto- or pre-stellar, and studied their association with the identified filaments. We find that although most (71%) of the pre-stellar sources are located on filaments there, is still a significant fraction of sources not associated with such structures. We find that these two populations (on and off the identified filaments) have distinctly different mass distributions. The mass distribution of the sources on the filaments is found to peak at 4 M {sub ☉} and drives the shape of the core mass function (CMF) at higher masses, which we fit with a power law of the form dN/dlogM∝M {sup –1.4±0.4}. The mass distribution of the sources off the filaments, on the other hand, peaks at 0.8 M {sub ☉} and leads to a flattening of the CMF at masses lower than ∼4 M {sub ☉}. We postulate that this difference between the mass distributions is due to the higher proportion of gas that is available in the filaments, rather than in the diffuse cloud.

  17. An analytical model for the evolution of starless cores - I. The constant-mass case

    Science.gov (United States)

    Pattle, K.

    2016-07-01

    We propose an analytical model for the quasi-static evolution of starless cores confined by a constant external pressure, assuming that cores are isothermal and obey a spherically symmetric density distribution. We model core evolution for Plummer-like and Gaussian density distributions in the adiabatic and isothermal limits, assuming Larson-like dissipation of turbulence. We model the variation in the terms in the virial equation as a function of core characteristic radius, and determine whether cores are evolving towards virial equilibrium or gravitational collapse. We ignore accretion on to cores in the current study. We discuss the different behaviours predicted by the isothermal and adiabatic cases, and by our choice of index for the size-linewidth relation, and suggest a means of parametrizing the magnetic energy term in the virial equation. We model the evolution of the set of cores observed by Pattle et al. in the L1688 region of Ophiuchus in the `virial plane'. We find that not all virially bound and pressure-confined cores will evolve to become gravitationally bound, with many instead contracting to virial equilibrium with their surroundings, and find an absence of gravitationally dominated and virially unbound cores. We hypothesize a `starless core desert' in this quadrant of the virial plane, which may result from cores initially forming as pressure-confined objects. We conclude that a virially bound and pressure-confined core will not necessarily evolve to become gravitationally bound, and thus cannot be considered pre-stellar. A core can only be definitively considered pre-stellar (collapsing to form an individual stellar system) if it is gravitationally unstable.

  18. Core Needle Biopsy and Fine Needle Aspiration Alone or in Combination: Diagnostic Accuracy and Impact on Management of Renal Masses.

    Science.gov (United States)

    Cate, Frances; Kapp, Meghan E; Arnold, Shanna A; Gellert, Lan L; Hameed, Omar; Clark, Peter E; Wile, Geoffrey; Coogan, Alice; Giannico, Giovanna A

    2017-06-01

    Fine needle aspiration with and without concurrent core needle biopsy is a minimally invasive method to diagnose and assist in management of renal masses. We assessed the pathological accuracy of fine needle aspiration compared to and associated with core needle biopsy and the impact on management. We performed a single institution, retrospective study of 342 cases from 2001 to 2015 with small and large renal masses (4 or less and greater than 4 cm, respectively). Diagnostic and concordance rates, and the impact on management were analyzed. Adequacy rates for fine needle aspiration only, core needle biopsy only and fine needle aspiration plus core needle biopsy were 21%, 12% and 8% (aspiration vs aspiration plus biopsy p aspiration plus biopsy group adding aspiration to biopsy and biopsy to aspiration reduced the inadequacy rate from 23% to 8% and from 27% to 8% for a total reduction rate of 15% and 19%, respectively, corresponding to 32 cases (9.3%). Rapid on-site examination contributed to a 22.5% improvement in fine needle aspiration adequacy rates. In this cohort 30% of aspiration only, 5% of biopsy only and 12% of aspiration plus biopsy could not be subtyped (aspiration vs biopsy p aspiration vs aspiration plus biopsy p biopsy vs aspiration plus biopsy p = 0.06). The diagnostic concordance rate with surgical resection was 99%. Conversion of an inadequate specimen to an adequate one by a concurrent procedure impacted treatment in at least 29 of 32 patients. Limitations include the retrospective design and accuracy measurement based on surgical intervention. Fine needle aspiration plus core needle biopsy vs at least fine needle aspiration alone may improve diagnostic yield when sampling renal masses but it has subtyping potential similar to that of core needle biopsy only. Copyright © 2017 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

  19. Two Mass Distributions in the L 1641 Molecular Clouds: The Herschel connection of Dense Cores and Filaments in Orion A

    CERN Document Server

    Polychroni, D; Elia, D; Roy, A; Molinari, S; Martin, P; Andre, Ph; Turrini, D; Rygl, K L J; Benedettini, M; Busquet, G; di Giorgio, A M; Pestalozzi, M; Pezzuto, S; Arzoumanian, D; Bontemps, S; Di Francesco, J; Hennemann, M; Hill, T; Konyves, V; Menshchikov, A; Motte, F; Nguyen-Luong, Q; Peretto, N; Schneider, N; White, G

    2013-01-01

    We present the Herschel Gould Belt survey maps of the L\\,1641 molecular clouds in Orion A. We extracted both the filaments and dense cores in the region. We identified which of dense sources are proto- or pre-stellar, and studied their association with the identified filaments. We find that although most (71%) of the pre-stellar sources are located on filaments there is still a significant fraction of sources not associated with such structures. We find that these two populations (on and off the identified filaments) have distinctly different mass distributions. The mass distribution of the sources on the filaments is found to peak at 4 Solar masses and drives the shape of the CMF at higher masses, which we fit with a power law of the form d$N$/dlog$M \\propto M^{-1.4\\pm0.4}$. The mass distribution of the sources off the filaments, on the other hand, peaks at 0.8 Solar masses and leads to a flattening of the CMF at masses lower than ~4 Solar masses. We postulate that this difference between the mass distributi...

  20. Microstructural observations of HFIR-irratiated austenitic stainless steels including welds from JP9-16

    Energy Technology Data Exchange (ETDEWEB)

    Sawai, T.; Shiba, K.; Hishinuma, A.

    1996-04-01

    Austenitic stainless steels, including specimens taken from various electron beam (EB) welds, have been irradiated in HFIR Phase II capsules, JP9-16. Fifteen specimens irradiated at 300, 400, and 500{degrees}C up to 17 dpa are so far examined by a transmission electron microscope (TEM). In 300{degrees}C irradiation, cavities were smaller than 2nm and different specimens showed little difference in cavity microstructure. At 400{degrees}C, cavity size was larger, but still very small (<8 nm). At 500{degrees}C, cavity size reached 30 nm in weld metal specimens of JPCA, while cold worked JPCA contained a small (<5 nm) cavities. Inhomogeneous microstructural evolution was clearly observed in weld-metal specimens irradiated at 500{degrees}C.

  1. Tensile properties of vanadium alloys irradiated at 200{degrees}C in the HFIR

    Energy Technology Data Exchange (ETDEWEB)

    Chung, H.M.; Nowicki, L.; Smith, D.L. [Argonne National Lab., IL (United States)

    1997-08-01

    Vanadium alloys were irradiated in a helium environment to {approx}10 dpa at {approx}200{degrees}C in the High Flux Isotope Reactor (HFIR). This report presents results of postirradiation tests of tensile properties of laboratory heats of V-(1-18)Ti, V-4Cr-4Ti, V-8Cr-6Ti, V-9Cr-5Ti, V-3Ti-1Si, and V-3Ti-0.1C alloys. Because of significant loss of work-hardening capability, all alloys except V-18Ti exhibited a very low uniform plastic strain <1%. For V-Ti. The mechanism of the loss of work-hardening capability in the other alloys is not understood.

  2. Saturation behavior of irradiation hardening in F82H irradiated in the HFIR

    Energy Technology Data Exchange (ETDEWEB)

    Hirose, T. [Blanket Engineering Group, Japan Atomic Energy Agency, Naka, Ibaraki (Japan); Shiba, K.; Tanigawa, H.; Ando, M. [Japan Atomic Energy Agency, Tokai-mura, Naga-gun, Ibaraki-ken (Japan); Klueh, R.L. [Oak Ridge National Laboratory, TN (United States); Stoller, R. [ORNL - Oak Ridge National Laboratory, Materials Science and Technology Div., Oak Ridge, AK TN (United States)

    2007-07-01

    Full text of publication follows: Post irradiation tensile tests on reduced activation ferritic/martensitic steel, F82H have been conducted over the past two decades using Japan Materials Testing Reactor (JMTR) of JAEA, and Fast Flux Testing Facility (FFTF) of PNNL and High Flux Isotope Reactor (HFIR) of ORNL, USA, under Japan/US collaboration programs. According to these results, F82H does not demonstrate irradiation hardening above 673 K up to 60 dpa. The current study has been concentrated on hardening behavior at temperature around 573 K. A series of low temperature irradiation experiment has been conducted at the HFIR under the international collaborative research between JAEA/US-DOE. In this collaboration, the irradiation condition is precisely controlled by the well matured capsule designing and instrumentation. This paper summarizes recent results of the irradiation experiments focused on F82H and its modified steels compared with the irradiation properties database on F82H. Post irradiation tensile tests have been conducted on the F82H and its modified steels irradiated at 573 K and the dose level was up to 25 dpa. According to these results, irradiation hardening of F82H is saturated by 9 dpa and the as-irradiated 0.2 % proof stress is less than 1 GPa at ambient temperature. The deterioration of total elongation was also saturated by 9 dpa irradiation. The ductility of some modified steels which showed larger total elongation than that of F82H before irradiation become the same level as that of standard F82H steel after irradiation, even though its magnitude of irradiation hardening is smaller than that of F82H. This suggests that the more ductile steel demonstrates the more ductility loss at this temperature, regardless to the hardening level. The difference in ductility loss behavior between various tensile specimens will be discussed as the ductility could depend on the specimen dimension. (authors)

  3. A CS J=5-->4 Mapping Survey Toward High-Mass Star-forming Cores Associated with Water Masers

    Science.gov (United States)

    Shirley, Yancy L.; Evans, Neal J., II; Young, Kaisa E.; Knez, Claudia; Jaffe, Daniel T.

    2003-12-01

    We have mapped 63 regions forming high-mass stars in CS J=5-->4 using the CSO. The CS peak position was observed in C34S J=5-->4 toward 57 cores and in 13CS J=5-->4 toward the nine brightest cores. The sample is a subset of a sample originally selected toward water masers; the selection on maser sources should favor sources in an early stage of evolution. The cores are located in the first and second Galactic quadrants with an average distance of 5.3+/-3.7 kpc and were well detected with a median peak signal-to-noise ratio in the integrated intensity of 40. The integrated intensity of CS J=5-->4 correlates very well with the dust continuum emission at 350 μm. For 57 sufficiently isolated cores, a well-defined angular size (FWHM) was determined. The core radius (RCS), aspect ratio [(a/b)obs], virial mass (Mvir), surface density (Σ), and the luminosity in the CS J=5-->4 line (L(CS54)) are calculated. The distributions of size, virial mass, surface density, and luminosity are all peaked with a few cores skewed toward much larger values than the mean. The median values, μ1/2, are as follows: μ1/2 (RCS)=0.32 pc, μ1/2 ((a/b)obs)=1.20, μ1/2 (Mvir)=920 Msolar, μ1/2 (Σ)=0.60 g cm-2, μ1/2 (L(CS54))=1.9×10-2 Lsolar, and μ1/2 (Lbol/Mvir)=165 (L/M)solar. We find a weak correlation between C34S line width and size, consistent with Δv~R0.3. The line widths are much higher than would be predicted by the usual relations between line width and size determined from regions of lower mass. These regions are very turbulent. The derived virial mass agrees within a factor of 2-3 with mass estimates from dust emission at 350 μm after corrections for the density structure are accounted for. The resulting cumulative mass spectrum of cores above 1000 Msolar can be approximated by a power law with a slope of about -0.9, steeper than that of clouds measured with tracers of lower density gas and close to that for the total masses of stars in OB associations. The median turbulent

  4. An analytical model for the evolution of starless cores I: The constant-mass case

    CERN Document Server

    Pattle, Kate

    2016-01-01

    We propose an analytical model for the quasistatic evolution of starless cores confined by a constant external pressure, assuming that cores are isothermal and obey a spherically-symmetric density distribution. We model core evolution for Plummer-like and Gaussian density distributions in the adiabatic and isothermal limits, assuming Larson-like dissipation of turbulence. We model the variation in the terms in the virial equation as a function of core characteristic radius, and determine whether cores are evolving toward virial equilibrium or gravitational collapse. We ignore accretion onto cores in the current study. We discuss the different behaviours predicted by the isothermal and adiabatic cases, and by our choice of index for the size-linewidth relation, and suggest a means of parameterising the magnetic energy term in the virial equation. We model the evolution of the set of cores observed by Pattle et al. (2015) in the L1688 region of Ophiuchus in the 'virial plane'. We find that not all virially-boun...

  5. Effect of OH depletion on measurements of the mass-to-flux ratio in molecular cloud cores

    CERN Document Server

    Tassis, K; Yorke, H W; Turner, N J

    2014-01-01

    The ratio of mass and magnetic flux determines the relative importance of magnetic and gravitational forces in the evolution of molecular clouds and their cores. Its measurement is thus central in discriminating between different theories of core formation and evolution. Here we discuss the effect of chemical depletion on measurements of the mass-to-flux ratio using the same molecule (OH) both for Zeeman measurements of the magnetic field and the determination of the mass of the region. The uncertainties entering through the OH abundance in determining separately the magnetic field and the mass of a region have been recognized in the literature. It has been proposed however that, when comparing two regions of the same cloud, the abundance will in both cases be the same. We show that this assumption is invalid. We demonstrate that when comparing regions with different densities, the effect of OH depletion in measuring changes of the mass-to-flux ratio between different parts of the same cloud can even reverse ...

  6. Power Relative to Body Mass Best Predicts Change in Core Temperature During Exercise-Heat Stress.

    Science.gov (United States)

    Gibson, Oliver R; Willmott, Ashley G B; James, Carl A; Hayes, Mark; Maxwell, Neil S

    2017-02-01

    Gibson, OR, Willmott, AGB, James, CA, Hayes, M, and Maxwell, NS. Power relative to body mass best predicts change in core temperature during exercise-heat stress. J Strength Cond Res 31(2): 403-414, 2017-Controlling internal temperature is crucial when prescribing exercise-heat stress, particularly during interventions designed to induce thermoregulatory adaptations. This study aimed to determine the relationship between the rate of rectal temperature (Trec) increase, and various methods for prescribing exercise-heat stress, to identify the most efficient method of prescribing isothermic heat acclimation (HA) training. Thirty-five men cycled in hot conditions (40° C, 39% R.H.) for 29 ± 2 minutes. Subjects exercised at 60 ± 9% V[Combining Dot Above]O2peak, with methods for prescribing exercise retrospectively observed for each participant. Pearson product moment correlations were calculated for each prescriptive variable against the rate of change in Trec (° C·h), with stepwise multiple regressions performed on statistically significant variables (p ≤ 0.05). Linear regression identified the predicted intensity required to increase Trec by 1.0-2.0° C between 20- and 45-minute periods and the duration taken to increase Trec by 1.5° C in response to incremental intensities to guide prescription. Significant (p ≤ 0.05) relationships with the rate of change in Trec were observed for prescriptions based on relative power (W·kg; r = 0.764), power (%Powermax; r = 0.679), rating of perceived exertion (RPE) (r = 0.577), V[Combining Dot Above]O2 (%V[Combining Dot Above]O2peak; r = 0.562), heart rate (HR) (%HRmax; r = 0.534), and thermal sensation (r = 0.311). Stepwise multiple regressions observed relative power and RPE as variables to improve the model (r = 0.791), with no improvement after inclusion of any anthropometric variable. Prescription of exercise under heat stress using power (W·kg or %Powermax) has the strongest relationship with the rate of change in

  7. Discovery of the Youngest Molecular Outflow associated with an Intermediate-mass protostellar Core, MMS-6/OMC-3

    CERN Document Server

    Takahashi, Satoko

    2011-01-01

    We present sub-arcsecond resolution HCN (4-3) and CO (3-2) observations made with the Submillimeter Array (SMA), toward an extremely young intermediate-mass protostellar core, MMS 6-main, located in the Orion Molecular Cloud 3 region (OMC-3). We have successfully imaged a compact molecular outflow lobe (~1500 AU) associated with MMS6-main, which is also the smallest molecular outflow ever found in the intermediate-mass protostellar cores. The dynamical time scale of this outflow is estimated to be <100 yr. The line width dramatically increases downstream at the end of the molecular outflow ({\\Delta}v~25 km s^{-1}), and clearly shows the bow-shock type velocity structure. The estimated outflow mass (~10^{-4} M_{sun}) and outflow size are approximately 2-4 orders and 1-3 orders of magnitude smaller, while the outflow force (~10^{-4} M_{sun} km s^{-1} yr^{-1}) is similar, as compared to the other molecular outflows studied in OMC-2/3. These results show that MMS 6-main is a protostellar core at the earliest e...

  8. DNC/HNC and N2D+/N2H+ ratios in high-mass star forming cores

    CERN Document Server

    Fontani, F; Furuya, K; Sakai, N; Aikawa, Y; Yamamoto, S

    2014-01-01

    Chemical models predict that the deuterated fraction (the column density ratio between a molecule containing D and its counterpart containing H) of N2H+, Dfrac(N2H+), is high in massive pre-protostellar cores and rapidly drops of an order of magnitude after the protostar birth, while that of HNC, Dfrac(HNC), remains constant for much longer. We tested these predictions by deriving Dfrac(HNC) in 22 high-mass star forming cores divided in three different evolutionary stages, from high-mass starless core candidates (HMSCs, 8) to high-mass protostellar objects (HMPOs, 7) to Ultracompact HII regions (UCHIIs, 7). For all of them, Dfrac (N2H+) was already determined through IRAM-30m Telescope observations, which confirmed the theoretical rapid decrease of Dfrac(N2H+) after protostar birth (Fontani et al. 2011). Therefore our comparative study is not affected by biases introduced by the source selection. We have found average Dfrac(HNC) of 0.012, 0.009 and 0.008 in HMSCs, HMPOs and UCHIIs, respectively, with no stati...

  9. Laser ablation inductively coupled plasma mass spectrometry: a new tool for trace element analysis in ice cores.

    Science.gov (United States)

    Reinhardt, H; Kriews, M; Miller, H; Schrems, O; Lüdke, C; Hoffmann, E; Skole, J

    2001-07-01

    A new method for the detection of trace elements in polar ice cores using laser ablation with subsequent inductively coupled plasma mass spectrometry analysis is described. To enable direct analysis of frozen ice samples a special laser ablation chamber was constructed. Direct analysis reduces the risk of contamination. The defined removal of material from the ice surface by means of a laser beam leads to higher spatial resolution (300-1000 microm) in comparison to investigations with molten ice samples. This is helpful for the detection of element signatures in annual layers of ice cores. The method was applied to the successful determination of traces for the elements Mg, Al, Fe, Zn, Cd, Pb, some rare-earth elements (REE) and minor constituents such as Ca and Na in ice cores. These selected elements serve as tracer elements for certain sources and their element signatures detected in polar ice cores can give hints to climate changes in the past. We report results from measurements of frozen ice samples, the achievable signal intensities, standard deviations and calibration graphs as well as the first signal progression of 205Pb in an 8,000-year-old ice core sample from Greenland. In addition, the first picture of a crater on an ice surface burnt by an IR laser made by cryogenic scanning electron microscopy is presented.

  10. Magnetized Converging Flows toward the Hot Core in the Intermediate/High-mass Star-forming Region NGC 6334 V

    Science.gov (United States)

    Juárez, Carmen; Girart, Josep M.; Zamora-Avilés, Manuel; Tang, Ya-Wen; Koch, Patrick M.; Liu, Hauyu Baobab; Palau, Aina; Ballesteros-Paredes, Javier; Zhang, Qizhou; Qiu, Keping

    2017-07-01

    We present Submillimeter Array (SMA) observations at 345 GHz toward the intermediate/high-mass cluster-forming region NGC 6334 V. From the dust emission we spatially resolve three dense condensations, the brightest one presenting the typical chemistry of a hot core. The magnetic field (derived from the dust polarized emission) shows a bimodal converging pattern toward the hot core. The molecular emission traces two filamentary structures at two different velocities, separated by 2 km s-1, converging to the hot core and following the magnetic field distribution. We compare the velocity field and the magnetic field derived from the SMA observations with magnetohydrodynamic simulations of star-forming regions dominated by gravity. This comparison allows us to show how the gas falls in from the larger-scale extended dense core (˜0.1 pc) of NGC 6334 V toward the higher-density hot core region (˜0.02 pc) through two distinctive converging flows dragging the magnetic field, whose strength seems to have been overcome by gravity.

  11. Interannual variability of the surface mass balance of West Antarctica from ITASE cores and ERA40 reanalyses, 1958-2000

    Energy Technology Data Exchange (ETDEWEB)

    Genthon, C. [CNRS/UJF, Laboratoire de Glaciologie et Geophysique de l' Environnement, 54 Rue Moliere, BP 96, Saint Martin d' Heres cedex (France); Kaspari, S. [University of Maine, Climate Change Institute, Orono, ME (United States); Mayewski, P.A. [University of Maine, Climate Change Institute, Orono, ME (United States); University of Maine, Department of Earth Sciences, Orono, ME (United States)

    2005-06-01

    Time series of west-Antarctic (WA) annual surface mass balance (SMB) from ITASE firn/ice cores are compared with the ECMWF 1958-2001 ERA40 reanalysis-based model forecasts. The ITASE series partially confirm the spatial structure of the signature of El Nino Southern Oscillation (ENSO) in WA precipitation as previously identified in ERA40 and other models. However, an improvement of ERA40's ability to reproduce the west-Antarctic SMB since the 1970s is evidenced and is probably related to the onset and increasing use of satellite data in late 1972 and 1978. Restricting the analysis to the 1973-2000 (satellite) period, interannual correlations between ITASE cores and ERA40 SMB series are generally significant (95% confidence level) but weak. The fraction of common variability increases when the series are spatially averaged, suggesting that small-scale perturbation (SSP) of the large-scale SMB variability significantly contributes to year-to-year variability in single core series. A comparison of stake network and core data from the South Pole suggests that SSP can almost fully obscure the large-scale component of the SMB variability as recorded in a single core. Because of SSP, the 1973-2000 period is too brief to verify whether all aspects of the WA large-scale signatures of ENSO and of the Antarctic Oscillation suggested by ERA40 are confirmed in the core series. More annually resolved field data from cores and stakes, spatially extended using high-resolution ground penetrating radar, are necessary to fully assess the relationship between the Antarctic SMB and the large-scale climate as currently suggested by meteorological and climate models. (orig.)

  12. Three-dimensional modeling of borehole data cored from engineering rock mass

    Institute of Scientific and Technical Information of China (English)

    HE Manchao; LI Xueyuan; LIU Bin; XU Nengxiong

    2007-01-01

    Vast data from the drilling and geophysical prospecting are reliable original information to describe the space state of engineering rock mass,and one of the main difficulties in three-dimensional (3D) modeling of engineering rock mass is the processing of the primary data.From the viewpoint of 3D modeling,the engineering rock masses are classified as four basic types according to their geometric characteristics of geologic structure:(1) continuum rock mass;(2) discontinuous rock mass;(3) overturned fold rock mass and (4) intrusive rock mass.Because drilling data are very important to describe the characters of multi-scale of the spatial data for rock mass,the rule of how to process drilling data is developed to help appropriately display them in the viewpoint of 3D space.According to the characteristics of rock mass layers,the processing method of drilling data for 3D modeling of engineering rock masses,along with the layer thicknesses,is also proposed,including the evaluation rules and the extensive direction for original borehole data.By this method,the typical 3D data modeled is completed and the model form of the engineering rock mass is developed.By this example,it is finally verified that the method presented is successful and feasible to process 3D engineering rock mass.

  13. Description and status of the U.S./JAERI HFIR-MFE-RB-10J irradiation capsule

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, J.P.; Lenox, K.E.; Grossbeck, M.L.; Rowcliffe, A.F. [Oak Ridge National Lab., TN (United States); Jitsukawa, S.; Shiba, K. [Japan Atomic Energy Research Inst. (Japan)

    1998-03-01

    This report describes the HFIR-MFE-RB-10J experiment conducted under the US DOE/Japan Atomic Energy Research Institute Collaborative Testing Program. The irradiation will take place in a Removable Beryllium (RB) position in the High Flux Isotope Reactor (HFIR) for approximately 8 cycles (about 4 dpa in steel). The experiment consists of two distinct parts: the upper region of the capsule will contain vanadium specimens operating at either 420 or 480 C and the lower region will contain austenitic and ferritic/martensitic steel specimens operating at 250 C. The capsule will be surrounded by a Eu{sub 2}O{sub 3} shield in order to harden the spectrum and prevent unwanted transmutations.

  14. Source Terms for HFIR Beam Tube Shielding Analyses, and a Complete Shielding Analysis of the HB-3 Tube

    Energy Technology Data Exchange (ETDEWEB)

    Bucholz, J.A.

    2000-07-01

    The High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory is in the midst of a massive upgrade program to enhance experimental facilities. The reactor presently has four horizontal experimental beam tubes, all of which will be replaced or redesigned. The HB-2 beam tube will be enlarged to support more guide tubes, while the HB-4 beam tube will soon include a cold neutron source.

  15. The methanol lines and hot core of OMC2-FIR4, an intermediate-mass protostar, with Herschel-HIFI

    CERN Document Server

    Kama, M; Maret, S; van der Tak, F; Caux, E; Ceccarelli, C; Fuente, A; Crimier, N; Lord, S; Bacmann, A; Baudry, A; Bell, T; Benedettini, M; Bergin, E A; Blake, G A; Boogert, A; Bottinelli, S; Cabrit, S; Caselli, P; Castets, A; Cernicharo, J; Codella, C; Comito, C; Coutens, A; Demyk, K; Encrenaz, P; Falgarone, E; Gerin, M; Goldsmith, P F; Helmich, F; Hennebelle, P; Henning, T; Herbst, E; Hily-Blant, P; Jacq, T; Kahane, C; Klotz, A; Langer, W; Lefloch, B; Lis, D; Lorenzani, A; Melnick, G; Nisini, B; Pacheco, S; Pagani, L; Parise, B; Pearson, J; Phillips, T; Salez, M; Saraceno, P; Schilke, P; Schuster, K; Tielens, A G G M; van der Wiel, M H D; Vastel, C; Viti, S; Wakelam, V; Walters, A; Wyrowski, F; Yorke, H; Cais, P; Güsten, R; Philipp, S; Klein, T

    2010-01-01

    In contrast with numerous studies on the physical and chemical structure of low- and high-mass protostars, much less is known about their intermediate-mass counterparts, a class of objects that could help to elucidate the mechanisms of star formation on both ends of the mass range. We present the first results from a rich HIFI spectral dataset on an intermediate-mass protostar, OMC2-FIR4, obtained in the CHESS (Chemical HErschel SurveyS of star forming regions) key programme. The more than 100 methanol lines detected between 554 and 961 GHz cover a range in upper level energy of 40 to 540 K. Our physical interpretation focusses on the hot core, but likely the cold envelope and shocked regions also play a role in reality, because an analysis of the line profiles suggests the presence of multiple emission components. An upper limit of 10^-6 is placed on the methanol abundance in the hot core, using a population diagram, large-scale source model and other considerations. This value is consistent with abundances ...

  16. Evaluation of The Value of Core Needle Biopsy in The Diagnosis of a Breast Mass

    Directory of Open Access Journals (Sweden)

    Asieh Sadat Fattahi

    2016-06-01

    Full Text Available Background: Core needle biopsy (CNB with histological findings is regarded as one of the most important diagnostic measures that make preoperative assessment and planning for appropriate treatment possible. The aim of this study was to determine the sensitivity and specificity of core biopsy results in our patients with benign and malignant breast lumps, especially for borderline breast lesions, by using a classification method.Methods: In this study, 116 patients who were referred to the Surgery Clinic of Ghaem Hospital, Mashhad University of Medical Sciences, Mashhad, Iran with breast lump and underwent diagnostic procedures such as mammography and ultrasound were selected. Core needle biopsy (Tru-cut #14 or 16 was performed. After that, excisional biopsy was done. The benign, malignant and unspecified samples obtained by core needle biopsy were evaluated with the samples of the surgical and pathological findings. Then, false positive, false negative, sensitivity, specificity, and diagnostic accuracy of the core needle biopsy method were calculated. Also, the National Health Service Breast Screening Program (NHSBSP classification was employed.Results: The mean age of the participants in this study was 39±13.13 years and the mean tumor size was 2.7 cm. An average of 3.35 biopsies was taken from all patients. Most of the pathology samples taken from CNB and excisional biopsy were compatible with invasive ductal carcinoma. Of the B type classifications, B5 was the most frequent in both methods. Borderline lesions B3 and B4 had a change in their category after surgery. About 2.5% of the samples in core biopsy were inadequate. Skin bruising was the most common core biopsy complication reported. While, the most common complication of excisional biopsy was hematoma. Accuracy, sensitivity, specificity, positive and negative predictive values of the core needle biopsy procedure compared with excisional biopsy was 95.5%, 92.6%, 100%, 100%, and 91

  17. Low-Mass Star Formation: From Molecular Cloud Cores to Protostars and Protoplanetary Disks

    Science.gov (United States)

    Inutsuka, S.-I.; Machida, M.; Matsumoto, T.; Tsukamoto, Y.; Iwasaki, K.

    2015-05-01

    This review describes realistic evolution of magnetic field and rotation of the protostars, dynamics of outflows and jets, and the formation and evolution of protoplanetary disks. Recent advances in the protostellar collapse simulations cover a huge dynamic range from molecular cloud core density to stellar density in a self-consistent manner and account for all the non-ideal magnetohydrodynamical effects, such as Ohmic resistivity, ambipolar diffusion, and Hall current. We explain the emergence of the first core, i.e., the quasi-hydrostatic object that consists of molecular gas, and the second core, i.e., the protostar. Ohmic dissipation largely removes the magnetic flux from the center of a collapsing cloud core. A fast well-collimated bipolar jet along the rotation axis of the protostar is driven after the magnetic field is re-coupled with warm gas (˜103 K) around the protostar. The circumstellar disk is born in the "dead zone", a region that is de-coupled from the magnetic field, and the outer radius of the disk increases with that of the dead zone during the early accretion phase. The rapid increase of the disk size occurs after the depletion of the envelope of molecular cloud core. The effect of Hall current may create two distinct populations of protoplanetary disks.

  18. Ice core evidence for a 20th century increase in surface mass balance in coastal Dronning Maud Land, East Antarctica

    Science.gov (United States)

    Philippe, Morgane; Tison, Jean-Louis; Fjøsne, Karen; Hubbard, Bryn; Kjær, Helle A.; Lenaerts, Jan T. M.; Drews, Reinhard; Sheldon, Simon G.; De Bondt, Kevin; Claeys, Philippe; Pattyn, Frank

    2016-10-01

    Ice cores provide temporal records of surface mass balance (SMB). Coastal areas of Antarctica have relatively high and variable SMB, but are under-represented in records spanning more than 100 years. Here we present SMB reconstruction from a 120 m-long ice core drilled in 2012 on the Derwael Ice Rise, coastal Dronning Maud Land, East Antarctica. Water stable isotope (δ18O and δD) stratigraphy is supplemented by discontinuous major ion profiles and continuous electrical conductivity measurements. The base of the ice core is dated to AD 1759 ± 16, providing a climate proxy for the past ˜ 250 years. The core's annual layer thickness history is combined with its gravimetric density profile to reconstruct the site's SMB history, corrected for the influence of ice deformation. The mean SMB for the core's entire history is 0.47 ± 0.02 m water equivalent (w.e.) a-1. The time series of reconstructed annual SMB shows high variability, but a general increase beginning in the 20th century. This increase is particularly marked during the last 50 years (1962-2011), which yields mean SMB of 0.61 ± 0.01 m w.e. a-1. This trend is compared with other reported SMB data in Antarctica, generally showing a high spatial variability. Output of the fully coupled Community Earth System Model (CESM) suggests that, although atmospheric circulation is the main factor influencing SMB, variability in sea surface temperatures and sea ice cover in the precipitation source region also explain part of the variability in SMB. Local snow redistribution can also influence interannual variability but is unlikely to influence long-term trends significantly. This is the first record from a coastal ice core in East Antarctica to show an increase in SMB beginning in the early 20th century and particularly marked during the last 50 years.

  19. THE L{proportional_to}{sigma}{sup 8} CORRELATION FOR ELLIPTICAL GALAXIES WITH CORES: RELATION WITH BLACK HOLE MASS

    Energy Technology Data Exchange (ETDEWEB)

    Kormendy, John [Department of Astronomy, University of Texas at Austin, 2515 Speedway, Mail Stop C1400, Austin, Texas 78712-1205 (United States); Bender, Ralf, E-mail: kormendy@astro.as.utexas.edu, E-mail: bender@mpe.mpg.de [Universitaets-Sternwarte, Scheinerstrasse 1, D-81679 Muenchen (Germany)

    2013-05-20

    We construct the Faber-Jackson correlation between velocity dispersion {sigma} and total galaxy luminosity L{sub V} separately for elliptical galaxies with and without cores. The coreless ellipticals show the well-known, steep relationship dlog {sigma}/dlog L{sub V} = 0.268 or L{sub V} {proportional_to}{sigma}{sup 3.74}. This corresponds to dlog {sigma}/dlog M = 0.203, where M is the stellar mass and we use M/L{proportional_to}L {sup 0.32}. In contrast, the velocity dispersions of core ellipticals increase much more slowly with L{sub V} and M: dlog {sigma}/dlog L{sub V} = 0.120, L{sub V} {proportional_to}{sigma}{sup 8.33}, and dlog {sigma}/dlog M = 0.091. Dissipationless major galaxy mergers are expected to preserve {sigma} according to the simplest virial-theorem arguments. However, numerical simulations show that {sigma} increases slowly in dry major mergers, with dlog {sigma}/dlog M {approx_equal} +0.15. In contrast, minor mergers cause {sigma} to decrease, with dlog {sigma}/dlog M {approx_equal} -0.05. Thus, the observed relation argues for dry major mergers as the dominant growth mode of the most massive ellipticals. This is consistent with what we know about the formation of cores. We know no viable way to explain galaxy cores except through dissipationless mergers of approximately equal-mass galaxies followed by core scouring by binary supermassive black holes. The observed, shallow {sigma}{proportional_to}L{sub V}{sup +0.12} relation for core ellipticals provides further evidence that they formed in dissipationless and predominantly major mergers. Also, it explains the observation that the correlation of supermassive black hole mass with velocity dispersion, M{sub .}{proportional_to}{sigma}{sup 4}, ''saturates'' at high M{sub .} such that M{sub .} becomes almost independent of {sigma}.

  20. Sound-Triggered Collapse of Stably Oscillating Low-Mass Cores in a Two-Phase Interstellar Medium

    CERN Document Server

    Zhang, Ui-Han; Chiueh, Tzihong

    2015-01-01

    Inspired by Barnard 68, a Bok globule, that undergoes stable oscillations, we perform multi-phase hydrodynamic simulations to analyze the stability of Bok globules. We show that a high-density soft molecular core, with an adiabatic index $\\gamma$ = 0.7 embedded in a warm isothermal diffuse gas, must have a small density gradient to retain the stability. Despite being stable, the molecular core can still collapse spontaneously as it will relax to develop a sufficiently large density gradient after tens of oscillations, or a few $10^7$ years. However, during its relaxation, the core may abruptly collapse triggered by the impingement of small-amplitude, long-wavelength ($\\sim$ 6 $-$ 36 pc) sound waves in the warm gas. This triggered collapse mechanism is similar to a sonoluminescence phenomenon, where underwater ultrasounds can drive air bubble coalescence. The collapse configuration is found to be different from both inside-out and outside-in models of low-mass star formation; nonetheless the mass flux is close...

  1. The earliest phases of star formation - A Herschel key project. The thermal structure of low-mass molecular cloud cores

    CERN Document Server

    Launhardt, R; Schmiedeke, A; Henning, Th; Krause, O; Balog, Z; Beuther, H; Birkmann, S; Hennemann, M; Kainulainen, J; Khanzadyan, T; Linz, H; Lippok, N; Nielbock, M; Pitann, J; Ragan, S; Risacher, C; Schmalzl, M; Shirley, Y L; Stecklum, B; Steinacker, J; Tackenberg, J

    2013-01-01

    The temperature and density structure of molecular cloud cores are the most important physical quantities that determine the course of the protostellar collapse and the properties of the stars they form. Nevertheless, density profiles often rely either on the simplifying assumption of isothermality or on observationally poorly constrained model temperature profiles. With the aim of better constraining the initial physical conditions in molecular cloud cores at the onset of protostellar collapse, we initiated the Guaranteed Time Key Project (GTKP) "The Earliest Phases of Star Formation" (EPoS) with the Herschel satellite. This paper gives an overview of the low-mass sources in the EPoS project, including all observations, the analysis method, and the initial results of the survey. We study the thermal dust emission of 12 previously well-characterized, isolated, nearby globules using FIR and submm continuum maps at up to eight wavelengths between 100 micron and 1.2 mm. Our sample contains both globules with sta...

  2. Gamma ray heating rates due to chromium isotopes in stellar core during late stages of high mass stars (>10M⊙

    Directory of Open Access Journals (Sweden)

    Nabi Jameel-Un

    2017-01-01

    Full Text Available Gamma ray heating rates are thought to play a crucial role during the pre-supernova stage of high mass stars. Gamma ray heating rates, due to β±-decay and electron (positron capture on chromium isotopes, are calculated using proton-neutron quasiparticle random phase approximation theory. The electron capture significantly affects the lepton fraction (Ye and accelerates the core contraction. The gamma rays emitted as a result of weak processes heat the core and tend to hinder the cooling and contraction due to electron capture and neutrino emission. The emitted gamma rays tend to produce enormous entropy and set the convection to play its role at this stage. The gamma heating rates, on 50-60Cr, are calculated for the density range 10 < ρ (g.cm-3 < 1011 and temperature range 107 < T (K < 3.0×1010.

  3. Dynamic Mass Transfer of Hemoglobin at the Aqueous/Ionic-Liquid Interface Monitored with Liquid Core Optical Waveguide.

    Science.gov (United States)

    Chen, Xuwei; Yang, Xu; Zeng, Wanying; Wang, Jianhua

    2015-08-04

    Protein transfer from aqueous medium into ionic liquid is an important approach for the isolation of proteins of interest from complex biological samples. We hereby report a solid-cladding/liquid-core/liquid-cladding sandwich optical waveguide system for the purpose of monitoring the dynamic mass-transfer behaviors of hemoglobin (Hb) at the aqueous/ionic liquid interface. The optical waveguide system is fabricated by using a hydrophobic IL (1,3-dibutylimidazolium hexafluorophosphate, BBimPF6) as the core, and protein solution as one of the cladding layer. UV-vis spectra are recorded with a CCD spectrophotometer via optical fibers. The recorded spectra suggest that the mass transfer of Hb molecules between the aqueous and ionic liquid media involve accumulation of Hb on the aqueous/IL interface followed by dynamic extraction/transfer of Hb into the ionic liquid phase. A part of Hb molecules remain at the interface even after the accomplishment of the extraction/transfer process. Further investigations indicate that the mass transfer of Hb from aqueous medium into the ionic liquid phase is mainly driven by the coordination interaction between heme group of Hb and the cationic moiety of ionic liquid, for example, imidazolium cation in this particular case. In addition, hydrophobic interactions also contribute to the transfer of Hb.

  4. Core and Wing Densities of Asymmetric Coronal Spectral Profiles: Implications for the Mass Supply of the Solar Corona

    Science.gov (United States)

    Patsourakos, S.; Klimchuk, J. A.; Young, P. R.

    2014-01-01

    Recent solar spectroscopic observations have shown that coronal spectral lines can exhibit asymmetric profiles, with enhanced emissions at their blue wings. These asymmetries correspond to rapidly upflowing plasmas at speeds exceeding approximately equal to 50 km per sec. Here, we perform a study of the density of the rapidly upflowing material and compare it with that of the line core that corresponds to the bulk of the plasma. For this task, we use spectroscopic observations of several active regions taken by the Extreme Ultraviolet Imaging Spectrometer of the Hinode mission. The density sensitive ratio of the Fe(sub XIV) lines at 264.78 and 274.20 Angstroms is used to determine wing and core densities.We compute the ratio of the blue wing density to the core density and find that most values are of order unity. This is consistent with the predictions for coronal nanoflares if most of the observed coronal mass is supplied by chromospheric evaporation driven by the nanoflares. However, much larger blue wing-to-core density ratios are predicted if most of the coronal mass is supplied by heated material ejected with type II spicules. Our measurements do not rule out a spicule origin for the blue wing emission, but they argue against spicules being a primary source of the hot plasma in the corona. We note that only about 40% of the pixels where line blends could be safely ignored have blue wing asymmetries in both Fe(sub XIV) lines. Anticipated sub-arcsecond spatial resolution spectroscopic observations in future missions could shed more light on the origin of blue, red, and mixed asymmetries.

  5. DISCOVERY OF PULSATIONS, INCLUDING POSSIBLE PRESSURE MODES, IN TWO NEW EXTREMELY LOW MASS, He-CORE WHITE DWARFS

    Energy Technology Data Exchange (ETDEWEB)

    Hermes, J. J.; Montgomery, M. H.; Winget, D. E.; Bell, Keaton J.; Harrold, Samuel T. [Department of Astronomy, University of Texas at Austin, Austin, TX 78712 (United States); Brown, Warren R.; Kenyon, Scott J. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Gianninas, A.; Kilic, Mukremin, E-mail: jjhermes@astro.as.utexas.edu [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks Street, Norman, OK 73019 (United States)

    2013-03-10

    We report the discovery of the second and third pulsating extremely low mass (ELM) white dwarfs (WDs), SDSS J111215.82+111745.0 (hereafter J1112) and SDSS J151826.68+065813.2 (hereafter J1518). Both have masses < 0.25 M{sub Sun} and effective temperatures below 10, 000 K, establishing these putatively He-core WDs as a cooler class of pulsating hydrogen-atmosphere WDs (DAVs, or ZZ Ceti stars). The short-period pulsations evidenced in the light curve of J1112 may also represent the first observation of acoustic (p-mode) pulsations in any WD, which provide an exciting opportunity to probe this WD in a complimentary way compared to the long-period g-modes that are also present. J1112 is a T{sub eff} =9590 {+-} 140 K and log g =6.36 {+-} 0.06 WD. The star displays sinusoidal variability at five distinct periodicities between 1792 and 2855 s. In this star, we also see short-period variability, strongest at 134.3 s, well short of the expected g-modes for such a low-mass WD. The other new pulsating WD, J1518, is a T{sub eff} =9900 {+-} 140 K and log g =6.80 {+-} 0.05 WD. The light curve of J1518 is highly non-sinusoidal, with at least seven significant periods between 1335 and 3848 s. Consistent with the expectation that ELM WDs must be formed in binaries, these two new pulsating He-core WDs, in addition to the prototype SDSS J184037.78+642312.3, have close companions. However, the observed variability is inconsistent with tidally induced pulsations and is so far best explained by the same hydrogen partial-ionization driving mechanism at work in classic C/O-core ZZ Ceti stars.

  6. Image guided versus palpation guided core needle biopsy of palpable breast masses: a prospective study

    Directory of Open Access Journals (Sweden)

    Smriti Hari

    2016-01-01

    Interpretation & conclusions: Our results showed that in palpable breast masses, image guided biopsy was superior to palpation guided biopsy in terms of sensitivity, false negative rate and repeat biopsy rates.

  7. Getting to the core of protein pharmaceuticals – comprehensive structure analysis by mass spectrometry

    DEFF Research Database (Denmark)

    Leurs, Ulrike; Mistarz, Ulrik Hvid; Rand, Kasper Dyrberg

    2015-01-01

    Protein pharmaceuticals are the fastest growing class of novel therapeutic agents, and have been a major research and development focus in the (bio)pharmaceutical industry. Due to their large size and structural diversity, biopharmaceuticals represent a formidable challenge regarding analysis....... Mass spectrometry has evolved as a powerful tool for the characterization of both primary and higher order structures of protein pharmaceuticals. Furthermore, the chemical and physical stability of protein drugs, as well as their pharmacokinetics are nowadays routinely determined by mass spectrometry...

  8. Surface mass balance and water stable isotopes derived from firn cores on three ice rises, Fimbul Ice Shelf, Antarctica

    Science.gov (United States)

    Vega, Carmen P.; Schlosser, Elisabeth; Divine, Dmitry V.; Kohler, Jack; Martma, Tõnu; Eichler, Anja; Schwikowski, Margit; Isaksson, Elisabeth

    2016-11-01

    Three shallow firn cores were retrieved in the austral summers of 2011/12 and 2013/14 on the ice rises Kupol Ciolkovskogo (KC), Kupol Moskovskij (KM), and Blåskimen Island (BI), all part of Fimbul Ice Shelf (FIS) in western Dronning Maud Land (DML), Antarctica. The cores were dated back to 1958 (KC), 1995 (KM), and 1996 (BI) by annual layer counting using high-resolution oxygen isotope (δ18O) data, and by identifying volcanic horizons using non-sea-salt sulfate (nssSO42-) data. The water stable isotope records show that the atmospheric signature of the annual snow accumulation cycle is well preserved in the firn column, especially at KM and BI. We are able to determine the annual surface mass balance (SMB), as well as the mean SMB values between identified volcanic horizons. Average SMB at the KM and BI sites (0.68 and 0.70 mw. e. yr-1) was higher than at the KC site (0.24 mw. e. yr-1), and there was greater temporal variability as well. Trends in the SMB and δ18O records from the KC core over the period of 1958-2012 agree well with other previously investigated cores in the area, thus the KC site could be considered the most representative of the climate of the region. Cores from KM and BI appear to be more affected by local meteorological conditions and surface topography. Our results suggest that the ice rises are suitable sites for the retrieval of longer firn and ice cores, but that BI has the best preserved seasonal cycles of the three records and is thus the most optimal site for high-resolution studies of temporal variability of the climate signal. Deuterium excess data suggest a possible effect of seasonal moisture transport changes on the annual isotopic signal. In agreement with previous studies, large-scale atmospheric circulation patterns most likely provide the dominant influence on water stable isotope ratios preserved at the core sites.

  9. Neutron and Gamma Fluxes and dpa Rates for HFIR Vessel Beltline Region (Present and Upgrade Designs)

    Energy Technology Data Exchange (ETDEWEB)

    Blakeman, E.D.

    2001-01-11

    The Oak Ridge National Laboratory (ORNL) High Flux Isotope Reactor (HFIR) is currently undergoing an upgrading program, a part of which is to increase the diameters of two of the four radiation beam tubes (HB-2 and HB-4). This change will cause increased neutron and gamma radiation dose rates at and near locations where the tubes penetrate the vessel wall. Consequently, the rate of radiation damage to the reactor vessel wall at those locations will also increase. This report summarizes calculations of the neutron and gamma flux (particles/cm{sup 2}/s) and the dpa rate (displacements/atom/s) in iron at critical locations in the vessel wall. The calculated dpa rate values have been recently incorporated into statistical damage evaluation codes used in the assessment of radiation induced embrittlement. Calculations were performed using models based on the discrete ordinates methodology and utilizing ORNL two-dimensional and three-dimensional discrete ordinates codes. Models for present and proposed beam tube designs are shown and their results are compared. Results show that for HB-2, the dpa rate in the vessel wall where the tube penetrates the vessel will be increased by {approximately}10 by the proposed enlargement. For HB-4, a smaller increase of {approximately}2.6 is calculated.

  10. Embrittlement of Cr-Mo steels after low fluence irradiation in HFIR

    Energy Technology Data Exchange (ETDEWEB)

    Klueh, R.L.; Alexander, D.J.

    1995-04-01

    The goal of this work is the determination of the possible effect of the simultaneous formation of helium and displacement damage during irradiation on the Charpy impact behavior. Subsize Charpy impact specimens of 9Cr-1MoVNb (modified 9Cr-1Mo) and 12Cr-1MoVW (Sandvik HT9) steels and 12Cr-1MoVW with 2%Ni (12Cr-1MOVW-2Ni) were irradiated in the High Flux Isotope Reactor (HFIR) at 300 and 400{degree}C to damage levels up to 2.5 dpa. The objective was to study the effect of the simultaneous formation of displacement damage and transmutation helium on impact toghness. Despite the low fluence relative to previous irradiations of these steels, significant increases in the ductile-brittle transition temperature (DBTT) occurred. The 12Cr-1MoVW-2Ni steel irradiated at 400{degree}C had the largest increase in DBTT and displayed indications of intergranular fracture. A mechanism is proposed to explain how helium can affect the fracture behaviour of this latter steel in the present tests, and how it affected all three steels in previous experiments, where the steels were irradiated to higher fluences.

  11. Effect of helium production on swelling of F82H irradiated in HFIR

    Energy Technology Data Exchange (ETDEWEB)

    Wakai, E. E-mail: wakai@realab01.tokai.jaeri.go.jp; Hashimoto, N.; Miwa, Y.; Robertson, J.P.; Klueh, R.L.; Shiba, K.; Jistukawa, S

    2000-12-01

    The effects of helium production and heat treatment on the swelling of F82H steel irradiated in the HFIR to 51 dpa have been investigated using {sup 10}B, {sup 58}Ni and {sup 60}Ni-doped specimens. The swelling of tempered F82H-std and F82H doped with {sup 10}B irradiated at 400 deg. C ranged from 0.52% to 1.2%, while the swelling of the non-tempered F82H doped with {sup 58}Ni or {sup 60}Ni was less than 0.02%. At 300 deg. C the swelling in all steels was insignificant. In the F82H + Ni, a high number of density carbides formed in the matrix at these temperatures. The production of helium atoms enhanced the swelling of the F82H steel. However, the non-tempered treatment for the F82H + Ni suppressed remarkably the swelling. The cause of low swelling in the F82H + Ni may be due to the occurrence of the high density of carbides acting as sinks or the decrease of mobility of vacancies interacting with carbon atoms in matrix.

  12. Mass flow rate sensitivity and uncertainty analysis in natural circulation boiling water reactor core from Monte Carlo simulations

    Energy Technology Data Exchange (ETDEWEB)

    Espinosa-Paredes, Gilberto, E-mail: gepe@xanum.uam.m [Area de Ingenieria en Recursos Energeticos, Universidad Autonoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco, 186, Col. Vicentina, Mexico D.F., 09340 (Mexico); Verma, Surendra P. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Priv. Xochicalco s/no., Col Centro, Apartado Postal 34, Temixco 62580 (Mexico); Vazquez-Rodriguez, Alejandro [Area de Ingenieria en Recursos Energeticos, Universidad Autonoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco, 186, Col. Vicentina, Mexico D.F., 09340 (Mexico); Nunez-Carrera, Alejandro [Comision Nacional de Seguridad Nuclear y Salvaguardias, Doctor Barragan 779, Col. Narvarte, Mexico D.F. 03020 (Mexico)

    2010-05-15

    Our aim was to evaluate the sensitivity and uncertainty of mass flow rate in the core on the performance of natural circulation boiling water reactor (NCBWR). This analysis was carried out through Monte Carlo simulations of sizes up to 40,000, and the size, i.e., repetition of 25,000 was considered as valid for routine applications. A simplified boiling water reactor (SBWR) was used as an application example of Monte Carlo method. The numerical code to simulate the SBWR performance considers a one-dimensional thermo-hydraulics model along with non-equilibrium thermodynamics and non-homogeneous flow approximation, one-dimensional fuel rod heat transfer. The neutron processes were simulated with a point reactor kinetics model with six groups of delayed neutrons. The sensitivity was evaluated in terms of 99% confidence intervals of the mean to understand the range of mean values that may represent the entire statistical population of performance variables. The regression analysis with mass flow rate as the predictor variable showed statistically valid linear correlations for both neutron flux and fuel temperature and quadratic relationship for the void fraction. No statistically valid correlation was observed for the total heat flux as a function of the mass flow rate although heat flux at individual nodes was positively correlated with this variable. These correlations are useful for the study, analysis and design of any NCBWR. The uncertainties were propagated as follows: for 10% change in the mass flow rate in the core, the responses for neutron power, total heat flux, average fuel temperature and average void fraction changed by 8.74%, 7.77%, 2.74% and 0.58%, respectively.

  13. Statistical analysis of the mass-to-flux ratio in turbulent cores: effects of magnetic field reversals and dynamo amplification

    CERN Document Server

    Bertram, Erik; Banerjee, Robi; Klessen, Ralf S

    2011-01-01

    We study the mass-to-flux ratio (M/\\Phi) of clumps and cores in simulations of supersonic, magnetohydrodynamical turbulence for different initial magnetic field strengths. We investigate whether the (M/\\Phi)-ratio of core and envelope, R = (M/\\Phi)_{core}/(M/\\Phi)_{envelope} can be used to distinguish between theories of ambipolar diffusion and turbulence-regulated star formation. We analyse R for different Lines-of-Sight (LoS) in various sub-cubes of our simulation box. We find that, 1) the average and median values of |R| for different times and initial magnetic field strengths are typically greater, but close to unity, 2) the average and median values of |R| saturate at average values of |R| ~ 1 for smaller magnetic fields, 3) values of |R| < 1 for small magnetic fields in the envelope are caused by field reversals when turbulence twists the field lines such that field components in different directions average out. Finally, we propose two mechanisms for generating values |R| ~< 1 for the weak and st...

  14. Percutaneous Excision of a Benign Breast Mass Using Ultrasound-guided, Vacuum-assisted Core Biopsy:A Review of 197 Cases with Long Term Follow-up

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Hoi Soo; Han, Heon; Kim, Sam Soo; Jeon, Yong Hwan; Lee, Ji Won; Kim, Hyoung Rae [Kangwon National University College of Medicine, Chuncheon (Korea, Republic of); Moon, Jin Hee; Lee, Hyun; Koh, Sung Hye [Hallym University College of Medicine, Chuncheon (Korea, Republic of); Kim, Sun Mi [Bundang Seoul National University Hospital, Seoul (Korea, Republic of)

    2010-03-15

    To assess long term results of excising benign masses using ultrasound (US)-guided, vacuum-assisted core biopsy (Mammotome). We enrolled 163 patients (197 masses) receiving US guided excision using vacuum-assisted core biopsy and follow-up sonography in this retrospective study. The masses were category 3 as determined by ultrasound imaging according to the Breast Imaging Reporting and Data System (BI-RADS) (n=145) or pathologically confirmed as benign masses by a previous core-needle biopsy although category 4a and 4b (n = 52). Pathology, the presence of hematoma and residual tissue, as well as scar formation were assessed. We diagnosed 190 (96.5%) benign masses, 4 (2.0%) malignant masses, and 3 (1.5%) high-risk lesions. Most (176 masses, 91.2%) were excised completely as demonstrated by the follow-up ultrasound examination. Scar changes were minimal (68.7%) or moderate (31.3%), with regression in 53%. US-guided excision using vacuum-assisted core biopsy is effective for the removal of benign breast masses. The majority of scars are minimal, with good cosmetic effect. However, subsequent excision should be done for malignant masses or phyllodes tumor because radiologic absence does not guarantee complete removal

  15. Determination of Common Adulterants in Herbal Medicine and Food Samples using Core-shell Column Coupled to Tandem Mass Spectrometry.

    Science.gov (United States)

    Al Lawati, Haider A J; Al Busaidi, Idris; Kadavilpparampu, Afsal M; Suliman, FakhrEldin O

    2017-03-01

    High-performance liquid chromatography coupled to tandem mass spectrometry was used to develop and validate a rapid method to qualitatively and quantitatively analyse 18 common adulterants in herbal medicine and food samples. Initially, the mobile phase composition was optimized in three different columns: core-shell, monolithic and standard 3.5-µm-particle-size columns. The results show that the core-shell column provides the best separation. Moreover, the tandem mass spectrometry was optimized. The linear range for all adulterants was 0.5-500 μg mL-1. Finally, the samples that were supplied by the Public Authority of Customer Protection, Ministry of Health, and those collected from the local market were analysed. The results indicate that 7 of 33 analysed samples contained adulterants. The adulterated samples mainly contain sildenafil, tadalafil or vardenafil. The concentrations of these three adulterants in the samples were 0.18-39 wt%. This study is the first report in the Sultanate of Oman about adulteration in herbal medicine and food samples. The results clearly raise some concern and require proper plan of action to increase public awareness about this serious issue.

  16. Single-core magnetic markers in rotating magnetic field based homogeneous bioassays and the law of mass action

    Energy Technology Data Exchange (ETDEWEB)

    Dieckhoff, Jan, E-mail: j.dieckhoff@tu-bs.de [Institut fuer Elektrische Messtechnik und Grundlagen der Elektrotechnik, TU Braunschweig, Braunschweig (Germany); Schrittwieser, Stefan; Schotter, Joerg [Molecular Diagnostics, AIT Austrian Institute of Technology, Vienna (Austria); Remmer, Hilke; Schilling, Meinhard; Ludwig, Frank [Institut fuer Elektrische Messtechnik und Grundlagen der Elektrotechnik, TU Braunschweig, Braunschweig (Germany)

    2015-04-15

    In this work, we report on the effect of the magnetic nanoparticle (MNP) concentration on the quantitative detection of proteins in solution with a rotating magnetic field (RMF) based homogeneous bioassay. Here, the phase lag between 30 nm iron oxide single-core particles and the RMF is analyzed with a fluxgate-based measurement system. As a test analyte anti-human IgG is applied which binds to the protein G functionalized MNP shell and causes a change of the phase lag. The measured phase lag changes for a fixed MNP and a varying analyte concentration are modeled with logistic functions. A change of the MNP concentration results in a nonlinear shift of the logistic function with the analyte concentration. This effect results from the law of mass action. Furthermore, the bioassay results are used to determine the association constant of the binding reaction. - Highlights: • A rotating magnetic field based homogeneous bioassay concept was presented. • Here, single-core iron oxide nanoparticles are applied as markers. • The impact of the particle concentration on the bioassay results is investigated. • The relation between particle concentration and bioassay sensitivity is nonlinear. • This finding can be reasonably explained by the law of mass action.

  17. Relationship between functional movement screen scores, core strength, posture, and body mass index in school children in Moldova.

    Science.gov (United States)

    Mitchell, Ulrike H; Johnson, A Wayne; Adamson, Brynn

    2015-05-01

    The assessment of functionality should include parameters that consider postural control, limb asymmetries, range of motion limitations, proprioceptive deficits, and pain. An increasingly popular battery of tests, the Functional Movement Screen (FMS), is purported to assess the above named parameters. The purpose of our study was twofold: (a) to report differences in total FMS scores in children, provide preliminary normative reference values of each of the 7 individual FMS scores for both genders and report on asymmetries and (b) to evaluate the relationship between total FMS scores, age, body mass index (BMI), core strength/stability, and postural angles to explore the possibility of using the FMS in the assessment of children's functional fitness. Descriptive data on 77 children aged 8-11 years were collected. The children performed core strength/stability exercises. Photographs were taken from a lateral view for later calculation of postural angles. The children performed the FMS while being videotaped for later review. The average total FMS score (of 21) was 14.9 (+1.9), and BMI was 16.4 (+2.2). Static posture is not related to results of the FMS. Core strength was positively correlated to the total FMS score (r = 0.31; p = 0.006). Over 60% demonstrated at least 1 asymmetry. The individual test scores indicate that none of the test items is too difficult for the children. Based on the screen's correlation to core strength, and the fact that it identifies areas of asymmetry, we suggest to further investigate its possible use in the assessment of children's functional fitness.

  18. Observation of HCN hyperfine line anomalies towards low- and high-mass star-forming cores

    CERN Document Server

    Loughnane, R M; Thompson, M A; Lo, N; O'Dwyer, B; Cunningham, M R; 10.1111/j.1365-2966.2011.20121.x

    2013-01-01

    HCN is becoming a popular choice of molecule for studying star formation in both low- and high-mass regions and for other astrophysical sources from comets to high-redshift galaxies. However, a major and often overlooked difficulty with HCN is that it can exhibit non-local thermodynamic equilibrium (non-LTE) behaviour in its hyperfine line structure. Individual hyperfine lines can be strongly boosted or suppressed. In low-mass star-forming cloud observations, this could possibly lead to large errors in the calculation of opacity and excitation temperature, while in massive star-forming clouds, where the hyperfine lines are blended due to turbulent broadening, errors will arise in infall measurements that are based on the separation of the peaks in a self-absorbed profile. The underlying line shape cannot be known for certain if hyperfine anomalies are present. We present a first observational investigation of these anomalies across a range of conditions and transitions by carrying out a survey of low-mass sta...

  19. The Minimum Mass for Opacity-Limited Fragmentation in Turbulent Cloud Cores

    CERN Document Server

    Whitworth, A P

    2004-01-01

    We present a new analysis of the minimum mass for star formation, based on opacity-limited fragmentation. Our analysis differs from the standard one, which considers hierarchical fragmentation of a 3-D medium, and yields $M_{_{\\rm MIN}} \\sim 0.007 {\\rm to} 0.010 M_\\odot$ for Population I star formation. Instead we analyse the more realistic situation in which there is one-shot fragmentation of a shock-compressed layer, of the sort which arises in turbulent star-forming clouds. In this situation, $M_{_{\\rm MIN}}$ can be smaller than $0.003 M_\\odot$. Our analysis is more stringent than the standard one in that (a) it requires fragments to have condensation timescales shorter than all competing mass scales, and (b) it takes into acount that a fragment grows by accretion whilst it is condensing out, and has to radiate away the energy dissipated in the associated accretion shock. It also accords with the recent detection, in young star clusters, of free-floating star-like objects having masses as low as $0.003 {\\r...

  20. Range of outward migration and influence of the disc's mass on the migration of giant planet cores

    Science.gov (United States)

    Bitsch, B.; Kley, W.

    2011-12-01

    planetary masses, resulting in a quite extended region where the formation of larger cores might be easier. In higher mass discs, convection changes the disc's structure resulting in fluctuations in the surface density, which influence the torque acting on the planet, and therefore its migration rate. Because convection is a 3D effect, 2D simulations of massive discs with embedded planets should be handled with care.

  1. Summary of the U.S. specimen matrix for the HFIR 13J varying temperature irradiation capsule

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J. [Oak Ridge National Lab., TN (United States)

    1998-03-01

    The US specimen matrix for the collaborative DOE/Monbusho HFIR 13J varying temperature irradiation capsule contains two ceramics and 29 different metals, including vanadium alloys, ferritic/martensitic steels, pure iron, austenitic stainless steels, nickel alloys, and copper alloys. This experiment is designed to provide fundamental information on the effects of brief low-temperature excursions on the tensile properties and microstructural evolution of a wide range of materials irradiated at nominal temperatures of 350 and 500 C to a dose of {approximately}5 dpa. A total of 340 miniature sheet tensile specimens and 274 TEM disks are included in the US-supplied matrix for the irradiation capsule.

  2. The SNS/HFIR Web Portal System How Can it Help Me?

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Stephen D [ORNL; Geist, Al [ORNL; Herwig, Kenneth W [ORNL; Peterson, Peter F [ORNL; Reuter, Michael A [ORNL; Ren, Shelly [ORNL; Bilheux, Jean-Christophe [ORNL; Campbell, Stuart I [ORNL; Kohl, James Arthur [ORNL; Vazhkudai, Sudharshan S [ORNL; Cobb, John W [ORNL; Lynch, Vickie E [ORNL; Chen, Meili [ORNL; Trater, James R [ORNL

    2010-01-01

    Abstract. In a busy world, continuing with the status-quo, to do things the way we are already familiar, often seems to be the most efficient way to conduct our work. We look for the value-add to decide if investing in a new method is worth the effort. How shall we evaluate if we have reached this tipping point for change? For contemporary researchers, understanding the properties of the data is a good starting point. The new generation of neutron scattering instruments being built are higher resolution and produce one or more orders of magnitude larger data than the previous generation of instruments. For instance, we have grown out of being able to perform some important tasks with our laptops the data are too big and the computations would simply take too long. These large datasets can be problematic as facility users now begin to grapple with many of the same issues faced by more established computing communities. These issues include data access, management, and movement, data format standards, distributed computing, and collaboration among others. The Neutron Science Portal has been architected, designed, and implemented to provide users with an easy-to-use interface for managing and processing data, while also keeping an eye on meeting modern cybersecurity requirements imposed on institutions. The cost of entry for users has been lowered by utilizing a web interface providing access to backend portal resources. Users can browse or search for data which they are allowed to see, data reduction applications can be run without having to load the software, sample activation calculations can be performed for SNS and HFIR beamlines, McStas simulations can be run on TeraGrid and ORNL computers, and advanced analysis applications such as those being produced by the DANSE project can be run. Behind the scenes is a live cataloging system which automatically catalogs and archives experiment data via the data management system, and provides proposal team members access

  3. Analysis of in-situ electrical conductivity data from the HFIR TRIST-ER1 experiment

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J.; Snead, L.L. [Oak Ridge National Lab., TN (United States); Shikama, T. [Tohoku Univ. (Japan)] [and others

    1997-08-01

    The current vs. applied voltage data generated from the HFIR TRIST-ER1 experiment have been analyzed to determine the electrical conductivity of the 15 aluminum oxide specimens and the MgO-insulated electrical cables as a function of irradiation dose. With the exception of the 0.05%Cr-doped sapphire (ruby) specimen, the electrical conductivity of the alumina specimens remained at the expected radiation induced conductivity (RIC) level of <10{sup -6} S/m during full-power reactor irradiation (10-16 kGy/s) at 450-500{degrees}C up to a maximum dose of {approximately}3 dpa. The ruby specimen showed a rapid initial increase in conductivity to {approximately}2 x 10{sup -4} S/m after {approximately}0.1 dpa, followed by a gradual decrease to <1 x 10{sup -6} S/m after 2 dpa. Nonohmic electrical behavior was observed in all of the specimens, and was attributed to preferential attraction of ionized electrons in the capsule gas to the unshielded low-side bare electrical leads emanating from the subcapsules. The electrical conductivity was determined from the slope of the specimen current vs. voltage curve at negative voltages, where the gas ionization effect was minimized. Dielectric breakdown tests performed on unirradiated mineral-insulated coaxial cables identical to those used in the high voltage coaxial cables during the 3-month irradiation is attributable to thermal dielectric breakdown in the glass seals at the end of the cables, as opposed to a radiation-induced electrical degradation (RIED) effect.

  4. A 17-billion-solar-mass black hole in a group galaxy with a diffuse core

    CERN Document Server

    Thomas, Jens; McConnell, Nicholas J; Greene, Jenny E; Blakeslee, John P; Janish, Ryan

    2016-01-01

    Quasars are associated with and powered by the accretion of material onto massive black holes; the detection of highly luminous quasars with redshifts greater than z = 6 suggests that black holes of up to ten billion solar masses already existed 13 billion years ago. Two possible present-day dormant descendants of this population of active black holes have been found in the galaxies NGC 3842 and NGC 4889 at the centres of the Leo and Coma galaxy clusters, which together form the central region of the Great Wall - the largest local structure of galaxies. The most luminous quasars, however, are not confined to such high-density regions of the early Universe; yet dormant black holes of this high mass have not yet been found outside of modern-day rich clusters. Here we report observations of the stellar velocity distribution in the galaxy NGC 1600 - a relatively isolated elliptical galaxy near the centre of a galaxy group at a distance of 64 Mpc from Earth. We use orbit superposition models to determine that the ...

  5. Prospective Study for Comparison of Endoscopic Ultrasound-Guided Tissue Acquisition Using 25- and 22-Gauge Core Biopsy Needles in Solid Pancreatic Masses.

    Directory of Open Access Journals (Sweden)

    Se Woo Park

    Full Text Available Although thicker needles theoretically allow more tissue to be collected, their decreased flexibility can cause mechanical damage to the endoscope, technical failure, and sample blood contamination. The effects of needle gauge on diagnostic outcomes of endoscopic ultrasound-guided fine-needle biopsy (EUS-FNB of pancreatic mass lesions remain unknown. This study compared procurement rates of histologic cores obtained from EUS-FNB of pancreatic masses using 25- and 22-gauge core biopsy needles.From March 2014 to July 2014, 66 patients with solid pancreatic mass underwent EUS-FNB with both 25- and 22-gauge core biopsy needles. Among them, 10 patients were excluded and thus 56 patients were eligible for the analyses. Needle sequences were randomly assigned, and two passes were made with each needle, consisting of 10 uniform to-and-fro movements on each pass with 10 mL syringe suction. A pathologist blinded to needle sequence evaluated specimens for the presence of histologic core.The mean patient age was 65.8 ± 9.5 years (range, 44-89 years; 35 patients (62.5% were men. The mean pancreatic mass size was 35.3 ± 17.1 mm (range 14-122.3 mm. Twenty-eight patients (50% had tumors at the pancreas head or uncinate process. There were no significant differences in procurement rates of histologic cores between 25-gauge (49/56, 87.5% and 22-gauge (46/56, 82.1%, P = 0.581 needles or diagnostic accuracy using only histologic cores (98% and 95%. There were no technical failures or procedure-related adverse events.The 25-gauge core biopsy needle could offer acceptable and comparable outcomes regarding diagnostic performance including histologic core procurement rates compared to the 22-gauge core biopsy needle, although the differences were not statistically significant.ClinicalTrials.gov NCT01795066.

  6. Organic Chemistry of Low-Mass Star-Forming Cores. I. 7 mm Spectroscopy of Chamaeleon MMSl

    Science.gov (United States)

    Cordiner, Martn A.; Charnley, Steven B.; Wirtstroem, Eva S.; Smith, Robert G.

    2012-01-01

    Observations are presented of emission lines from organic molecules at frequencies 32-50 GHz in the vicinity of Chamaeleon MMS1. This chemically rich dense cloud core harbors an extremely young, very low luminosity protostellar object and is a candidate first hydrostatic core. Column densities are derived and emission maps are presented for species including polyynes, cyanopolyynes, sulphuretted carbon chains, and methanol. The polyyne emission peak lies about 5000 AU from the protostar, whereas methanol peaks about 15,000 AU away. Averaged over the telescope beam, the molecular hydrogen number density is calculated to be 10(exp 6) / cubic cm and the gas kinetic temperature is in the range 5-7 K. The abundances of long carbon chains are very large and are indicative of a nonequilibrium carbon chemistry; C6H and HC7N column densities are 5.9(sup +2.9) (sub -1.3) x 10(exp 11) /cubic cm and 3.3 (sup +8.0)(sub -1.5) x 10(exp 12)/sq cm, respectively, which are similar to the values found in the most carbon-chain-rich protostars and prestellar cores known, and are unusually large for star-forming gas. Column density upper limits were obtained for the carbon chain anions C4H(-) and C6H(-), with anion-to-neutral ratios [C4H(-)]/[C4H] < 0.02% and [C6H(-l)]/[C6H] < 10%, consistent with previous observations in interstellar clouds and low-mass protostars. Deuterated HC,3 and c-C3H2 were detected. The [DC3N]/[HC,N] ratio of approximately 4% is consistent with the value typically found in cold interstellar gas.

  7. Organic Chemistry of Low-Mass Star-Forming Cores. I. 7 mm Spectroscopy of Chamaeleon MMSl

    Science.gov (United States)

    Cordiner, Martn A.; Charnley, Steven B.; Wirtstroem, Eva S.; Smith, Robert G.

    2012-01-01

    Observations are presented of emission lines from organic molecules at frequencies 32-50 GHz in the vicinity of Chamaeleon MMS1. This chemically rich dense cloud core harbors an extremely young, very low luminosity protostellar object and is a candidate first hydrostatic core. Column densities are derived and emission maps are presented for species including polyynes, cyanopolyynes, sulphuretted carbon chains, and methanol. The polyyne emission peak lies about 5000 AU from the protostar, whereas methanol peaks about 15,000 AU away. Averaged over the telescope beam, the molecular hydrogen number density is calculated to be 10(exp 6) / cubic cm and the gas kinetic temperature is in the range 5-7 K. The abundances of long carbon chains are very large and are indicative of a nonequilibrium carbon chemistry; C6H and HC7N column densities are 5.9(sup +2.9) (sub -1.3) x 10(exp 11) /cubic cm and 3.3 (sup +8.0)(sub -1.5) x 10(exp 12)/sq cm, respectively, which are similar to the values found in the most carbon-chain-rich protostars and prestellar cores known, and are unusually large for star-forming gas. Column density upper limits were obtained for the carbon chain anions C4H(-) and C6H(-), with anion-to-neutral ratios [C4H(-)]/[C4H] < 0.02% and [C6H(-l)]/[C6H] < 10%, consistent with previous observations in interstellar clouds and low-mass protostars. Deuterated HC,3 and c-C3H2 were detected. The [DC3N]/[HC,N] ratio of approximately 4% is consistent with the value typically found in cold interstellar gas.

  8. Organic Chemistry of Low-Mass Star-Forming Cores. I. 7 mm Spectroscopy of Chamaeleon MMSl

    Science.gov (United States)

    Cordiner, Martn A.; Charnley, Steven B.; Wirtstroem, Eva S.; Smith, Robert G.

    2012-01-01

    Observations are presented of emission lines from organic molecules at frequencies 32-50 GHz in the vicinity of Chamaeleon MMS1. This chemically rich dense cloud core harbors an extremely young, very low luminosity protostellar object and is a candidate first hydrostatic core. Column densities are derived and emission maps are presented for species including polyynes, cyanopolyynes, sulphuretted carbon chains, and methanol. The polyyne emission peak lies about 5000 AU from the protostar, whereas methanol peaks about 15,000 AU away. Averaged over the telescope beam, the molecular hydrogen number density is calculated to be 10(exp 6) / cubic cm and the gas kinetic temperature is in the range 5-7 K. The abundances of long carbon chains are very large and are indicative of a nonequilibrium carbon chemistry; C6H and HC7N column densities are 5.9(sup +2.9) (sub -1.3) x 10(exp 11) /cubic cm and 3.3 (sup +8.0)(sub -1.5) x 10(exp 12)/sq cm, respectively, which are similar to the values found in the most carbon-chain-rich protostars and prestellar cores known, and are unusually large for star-forming gas. Column density upper limits were obtained for the carbon chain anions C4H(-) and C6H(-), with anion-to-neutral ratios [C4H(-)]/[C4H] mass protostars. Deuterated HC,3 and c-C3H2 were detected. The [DC3N]/[HC,N] ratio of approximately 4% is consistent with the value typically found in cold interstellar gas.

  9. Very cold and massive cores near ISOSS J18364-0221: Implications for the initial conditions of high-mass star-formation

    CERN Document Server

    Birkmann, S M; Lemke, D; Birkmann, Stephan M.; Krause, Oliver; Lemke, Dietrich

    2006-01-01

    We report the discovery of two very cold and massive molecular cloud cores in the region ISOSS J18364-0221. The object has been identified by a systematic search for very early evolutionary stages of high-mass stars using the 170 micron ISOPHOT Serendipity Survey (ISOSS). Submm continuum and molecular line measurements reveal two compact cores within this region. The first core has a temperature of 16.5 K, shows signs of ongoing infall and outflows, has no NIR or MIR counterpart and is massive enough (M ~ 75 M_sun) to form at least one O star with an associated cluster. It is therefore considered a candidate for a genuine high-mass protostar and a high-mass analog to the Class 0 objects. The second core has an average gas and dust temperature of only ~ 12 K and a mass of M ~ 280 M_sun. Its temperature and level of turbulence are below the values found for massive cores so far and are suggested to represent the initial conditions from which high-mass star formation occurs.

  10. Herschel/HIFI observations of spectrally resolved methylidyne signatures toward the high-mass star forming core NGC6334I

    CERN Document Server

    van der Wiel, M H D; Lis, D C; Bergin, E A; Comito, C; Emprechtinger, M; Schilke, P; Caux, E; Ceccarelli, C; Baudry, A; Goldsmith, P F; Herbst, E; Langer, W; Lord, S; Neufeld, D; Pearson, J; Philips, T; Rolffs, R; Yorke, H; Bacmann, A; Benedettini, M; Blake, G A; Boogert, A; Bottinelli, S; Cabrit, S; Caselli, P; Castets, A; Cernicharo, J; Codella, C; Coutens, A; Crimier, N; Demyk, K; Dominik, C; Encrenaz, P; Falgarone, E; Fuente, A; Gerin, M; Helmich, F; Hennebelle, P; Henning, T; Hily-Blant, P; Jacq, T; Kahane, C; Kama, M; Klotz, A; Lefloch, B; Lorenzani, A; Maret, S; Melnick, G; Nisini, B; Pacheco, S; Pagani, L; Parise, B; Salez, M; Saraceno, P; Schuster, K; Tielens, A G G M; Vastel, C; Viti, S; Wakelam, V; Walters, A; Wyrowski, F; Edwards, K; Zmuidzinas, J; Morris, P; Samoska, L A; Teyssier, D

    2010-01-01

    In contrast to extensively studied dense star forming cores, little is known about diffuse gas surrounding star forming regions. We aim to study molecular gas in the high-mass star forming region NGC6334I, including diffuse, quiescent components which are inconspicuous in widely used molecular tracers such as CO. We present Herschel/HIFI observations of CH toward NGC6334I observed as part of the CHESS Key Program. HIFI resolves the hyperfine components of its J=3/2-1/2 transition, observed in emission as well as in absorption. The CH emission appears close to the systemic velocity of NGC6334I, while a linewidth of 3 km/s is smaller than previously observed in dense gas tracers such as NH3 and SiO. The CH abundance in the hot core is 7 10^-11, two to three orders of magnitude lower than in diffuse clouds. While other studies find distinct outflows in, e.g., CO and H2O toward NGC6334I, we do not detect outflow signatures in CH. To explain the absorption signatures, at least two absorbing components are needed a...

  11. Pore to Core Scale Simulation of the Mass Transfer with Mineral Reaction in Porous Media

    Directory of Open Access Journals (Sweden)

    Bekri S.

    2015-04-01

    Full Text Available Pore Network Model (PNM is used to simulate mass transfer with mineral reaction in a single phase flow through porous medium which is here a sandstone sample from the reservoir formation of the Pakoslaw gas field. The void space of the porous medium is represented by an idealized geometry of pore-bodies joined by pore-throats. Parameters defining the pore-bodies and the pore-throats distribution are determined by an optimization process aiming to match the experimental Mercury Intrusion Capillary Pressure (MICP curve and petrophysical properties of the rock such as intrinsic permeability and formation factor. The generated network is used first to simulate the multiphase flow by solving Kirchhoff’s laws. The capillary pressure and relative permeability curves are derived. Then, reactive transport is addressed under asymptotic regime where the solute concentration undergoes an exponential evolution with time. The porosity/permeability relationship and the three phenomenological coefficients of transport, namely the solute velocity, the dispersion and the mean reaction rate are determined as functions of Peclet and Peclet-Damköhler dimensionless numbers. Finally, the role of the dimensionless numbers on the reactive flow properties is highlighted.

  12. Simulated Irradiation of Samples in HFIR for use as Possible Test Materials in the MPEX (Material Plasma Exposure Experiment) Facility

    Energy Technology Data Exchange (ETDEWEB)

    Ellis, Ronald James [ORNL; Rapp, Juergen [ORNL

    2014-01-01

    The importance of Plasma Material Interaction (PMI) is a major concern in fusion reactor design and analysis. The Material-Plasma Exposure eXperiment (MPEX) facility will explore PMI under fusion reactor plasma conditions. Samples with accumulated displacements per atom (DPA) damage produced by irradiations in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) will be studied in the MPEX facility. The project presented in this paper involved performing assessments of the induced radioactivity and resulting radiation fields of a variety of potential fusion reactor materials. The scientific code packages MCNP and SCALE were used to simulate irradiation of the samples in HFIR; generation and depletion of nuclides in the material and the subsequent composition, activity levels, gamma radiation fields, and resultant dose rates as a function of cooling time. These state-of-the-art simulation methods were used in addressing the challenge of the MPEX project to minimize the radioactive inventory in the preparation of the samples for inclusion in the MPEX facility.

  13. Magnetic Inhibition of Convection and the Fundamental Properties of Low-Mass Stars. I. Stars with a Radiative Core

    CERN Document Server

    Feiden, Gregory A

    2013-01-01

    Magnetic fields are hypothesized to inflate the radii of low-mass stars---defined as less massive than 0.8 solar masses---in detached eclipsing binaries (DEBs). We investigate this hypothesis using the recently introduced magnetic Dartmouth stellar evolution code. In particular, we focus on stars thought to have a radiative core and convective outer envelope by studying in detail three individual DEBs: UV Psc, YY Gem, and CU Cnc. The results suggest that the stabilization of thermal convection by a magnetic field is a plausible explanation for the observed model-radius discrepancies. However, surface magnetic field strengths required by the models are significantly stronger than those estimated from the observed coronal X-ray emission. Agreement between model predicted surface magnetic field strengths and those inferred from X-ray observations can be found by assuming that the magnetic field sources its energy from convection. This approach makes the transport of heat by convection less efficient and is akin ...

  14. Progenitor-Explosion Connection and Remnant Birth Masses for Neutrino-Driven Supernovae of Iron-Core Progenitors

    CERN Document Server

    Ugliano, Marcella; Marek, Andreas; Arcones, Almudena

    2012-01-01

    We perform hydrodynamic supernova simulations in spherical symmetry for over 100 single stars of solar metallicity to explore the progenitor-explosion and progenitor-remnant connections established by the neutrino-driven mechanism. We use an approximative treatment of neutrino transport and replace the high-density interior of the neutron star (NS) by an inner boundary condition based on an analytic proto-NS core-cooling model, whose free parameters are chosen such that explosion energy, nickel production, and energy release by the compact remnant of progenitors around 20 solar masses are compatible with Supernova 1987A. Thus we are able to simulate the accretion phase, initiation of the explosion, subsequent neutrino-driven wind phase for 15-20 s, and the further evolution of the blast wave for hours to days until fallback is completed. Our results challenge long-standing paradigms. We find that remnant mass, launch time, and properties of the explosion depend strongly on the stellar structure and exhibit la...

  15. Production of Medical Radioisotopes in the ORNL High Flux Isotope Reactor (HFIR) for Cancer Treatment and Arterial Restenosis Therapy after PTCA

    Science.gov (United States)

    Knapp, F. F. Jr.; Beets, A. L.; Mirzadeh, S.; Alexander, C. W.; Hobbs, R. L.

    1998-06-01

    The High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory (ORNL) represents an important resource for the production of a wide variety of medical radioisotopes. In addition to serving as a key production site for californium-252 and other transuranic elements, important examples of therapeutic radioisotopes which are currently routinely produced in the HFIR for distribution include dysprosium-166 (parent of holmium-166), rhenium-186, tin-117m and tungsten-188 (parent of rhenium-188). The nine hydraulic tube (HT) positions in the central high flux region permit the insertion and removal of targets at any time during the operating cycle and have traditionally represented a major site for production of medical radioisotopes. To increase the irradiation capabilities of the HFIR, special target holders have recently been designed and fabricated which will be installed in the six Peripheral Target Positions (PTP), which are also located in the high flux region. These positions are only accessible during reactor refueling and will be used for long-term irradiations, such as required for the production of tin-117m and tungsten-188. Each of the PTP tubes will be capable of housing a maximum of eight HT targets, thus increasing the total maximum number of HT targets from the current nine, to a total of 57. In this paper the therapeutic use of reactor-produced radioisotopes for bone pain palliation and vascular brachytherapy and the therapeutic medical radioisotope production capabilities of the ORNL HFIR are briefly discussed.

  16. Production of medical radioisotopes in the ORNL High Flux Isotope Reactor (HFIR) for cancer treatment and arterial restenosis therapy after PTCA

    Energy Technology Data Exchange (ETDEWEB)

    Knapp, F.F. Jr.; Beets, A.L.; Mirzadeh, S.; Alexander, C.W.; Hobbs, R.L.

    1998-06-01

    The High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory (ORNL) represents an important resource for the production of a wide variety of medical radioisotopes. In addition to serving as a key production site for californium-252 and other transuranic elements, important examples of therapeutic radioisotopes which are currently routinely produced in the HFIR for distribution include dysprosium-166 (parent of holmium-166), rhenium-186, tin-117m and tungsten-188 (parent of rhenium-188). The nine hydraulic tube (HT) positions in the central high flux region permit the insertion and removal of targets at any time during the operating cycle and have traditionally represented a major site for production of medical radioisotopes. To increase the irradiation capabilities of the HFIR, special target holders have recently been designed and fabricated which will be installed in the six Peripheral Target Positions (PTP), which are also located in the high flux region. These positions are only accessible during reactor refueling and will be used for long-term irradiations, such as required for the production of tin-117m and tungsten-188. Each of the PTP tubes will be capable of housing a maximum of eight HT targets, thus increasing the total maximum number of HT targets from the current nine, to a total of 57. In this paper the therapeutic use of reactor-produced radioisotopes for bone pain palliation and vascular brachytherapy and the therapeutic medical radioisotope production capabilities of the ORNL HFIR are briefly discussed.

  17. Defect annealing and thermal desorption of deuterium in low dose HFIR neutron-irradiated tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Masashi Shimada; M. Hara; T. Otsuka; Y. Oya; Y. Hatano

    2014-05-01

    for the sample exposed to TPE at 500 °C. Tritium Migration Analysis Program (TMAP) analysis reveals that the detrapping energy decreases from 1.8 eV to 1.4 eV, indicating the changes in trapping mechanisms. This paper also summarizes deuterium behavior studies in HFIR neutron-irradiated tungsten under US-Japan TITAN program.

  18. The SNS/HFIR Web Portal System - How Can it Help Me?

    Science.gov (United States)

    Miller, Stephen D.; Geist, Al; Herwig, Kenneth W.; Peterson, Peter F.; Reuter, Michael A.; Ren, Shelly; Bilheux, Jean-Christophe; Campbell, Stuart I.; Kohl, James A.; Vazhkudai, Sudharshan S.; Cobb, John W.; Lynch, Vickie E.; Chen, Meili; Trater, James R.; Smith, Bradford C.; (William Swain, Tom; Huang, Jian; Mikkelson, Ruth; Mikkelson, Dennis; een, Mar K. L. Gr

    2010-11-01

    In a busy world, continuing with the status-quo, to do things the way we are already familiar, often seems to be the most efficient way to conduct our work. We look for the value-add to decide if investing in a new method is worth the effort. How shall we evaluate if we have reached this tipping point for change? For contemporary researchers, understanding the properties of the data is a good starting point. The new generation of neutron scattering instruments being built are higher resolution and produce one or more orders of magnitude larger data than the previous generation of instruments. For instance, we have grown out of being able to perform some important tasks with our laptops - the data are too big and the computations would simply take too long. These large datasets can be problematic as facility users now begin to grapple with many of the same issues faced by more established computing communities. These issues include data access, management, and movement, data format standards, distributed computing, and collaboration among others. The Neutron Science Portal has been architected, designed, and implemented to provide users with an easy-to-use interface for managing and processing data, while also keeping an eye on meeting modern cybersecurity requirements imposed on institutions. The cost of entry for users has been lowered by utilizing a web interface providing access to backend portal resources. Users can browse or search for data which they are allowed to see, data reduction applications can be run without having to load the software, sample activation calculations can be performed for SNS and HFIR beamlines, McStas simulations can be run on TeraGrid and ORNL computers, and advanced analysis applications such as those being produced by the DANSE project can be run. Behind the scenes is a "live cataloging" system which automatically catalogs and archives experiment data via the data management system, and provides proposal team members access to

  19. The SNS/HFIR Web Portal System - How Can it Help Me?

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Stephen D; Geist, Al; Herwig, Kenneth W; Peterson, Peter F; Reuter, Michael A; Ren, Shelly; Bilheux, Jean-Christophe; Campbell, Stuart I; Kohl, James A; Vazhkudai, Sudharshan S; Cobb, John W; Lynch, Vickie E; Chen Meili; Trater, James R; Smith, Bradford C; Swain, Tom; Huang Jian [University of Tennessee, Knoxville, TN (United States); Mikkelson, Ruth; Mikkelson, Dennis, E-mail: millersd@ornl.gov

    2010-11-01

    In a busy world, continuing with the status-quo, to do things the way we are already familiar, often seems to be the most efficient way to conduct our work. We look for the value-add to decide if investing in a new method is worth the effort. How shall we evaluate if we have reached this tipping point for change? For contemporary researchers, understanding the properties of the data is a good starting point. The new generation of neutron scattering instruments being built are higher resolution and produce one or more orders of magnitude larger data than the previous generation of instruments. For instance, we have grown out of being able to perform some important tasks with our laptops - the data are too big and the computations would simply take too long. These large datasets can be problematic as facility users now begin to grapple with many of the same issues faced by more established computing communities. These issues include data access, management, and movement, data format standards, distributed computing, and collaboration among others. The Neutron Science Portal has been architected, designed, and implemented to provide users with an easy-to-use interface for managing and processing data, while also keeping an eye on meeting modern cybersecurity requirements imposed on institutions. The cost of entry for users has been lowered by utilizing a web interface providing access to backend portal resources. Users can browse or search for data which they are allowed to see, data reduction applications can be run without having to load the software, sample activation calculations can be performed for SNS and HFIR beamlines, McStas simulations can be run on TeraGrid and ORNL computers, and advanced analysis applications such as those being produced by the DANSE project can be run. Behind the scenes is a 'live cataloging' system which automatically catalogs and archives experiment data via the data management system, and provides proposal team members

  20. 22-gauge core vs 22-gauge aspiration needle for endoscopic ultrasound-guided sampling of abdominal masses.

    Science.gov (United States)

    Sterlacci, William; Sioulas, Athanasios D; Veits, Lothar; Gönüllü, Pervin; Schachschal, Guido; Groth, Stefan; Anders, Mario; Kontos, Christos K; Topalidis, Theodoros; Hinsch, Andrea; Vieth, Michael; Rösch, Thomas; Denzer, Ulrike W

    2016-10-21

    To compare the aspiration needle (AN) and core biopsy needle (PC) in endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) of abdominal masses. Consecutive patients referred for EUS-FNA were included in this prospective single-center trial. Each patient underwent a puncture of the lesion with both standard 22-gauge (G) AN (Echo Tip Ultra; Cook Medical, Bloomington, Indiana, United States) and the novel 22G PC (EchoTip ProCore; Cook Medical, Bloomington, Indiana, United States) in a randomized fashion; histology was attempted in the PC group only. The main study endpoint was the overall diagnostic accuracy, including the contribution of histology to the final diagnosis. Secondary outcome measures included material adequacy, number of needle passes, and complications. Fifty six consecutive patients (29 men; mean age 68 years) with pancreatic lesions (n = 38), lymphadenopathy (n = 13), submucosal tumors (n = 4), or others lesions (n = 1) underwent EUS-FNA using both of the needles in a randomized order. AN and PC reached similar overall results for diagnostic accuracy (AN: 88.9 vs PC: 96.1, P = 0.25), specimen adequacy (AN: 96.4% vs PC: 91.1%, P = 0.38), mean number of passes (AN: 1.5 vs PC: 1.7, P = 0.14), mean cellularity score (AN: 1.7 vs PC: 1.1, P = 0.058), and complications (none). A diagnosis on the basis of histology was achieved in the PC group in 36 (64.3%) patients, and in 2 of those as the sole modality. In patients with available histology the mean cellularity score was higher for AN (AN: 1.7 vs PC: 1.0, P = 0.034); no other differences were of statistical significance. Both needles achieved high overall diagnostic yields and similar performance characteristics for cytological diagnosis; histological analysis was only possible in 2/3 of cases with the new needle.

  1. ORGANIC CHEMISTRY OF LOW-MASS STAR-FORMING CORES. I. 7 mm SPECTROSCOPY OF CHAMAELEON MMS1

    Energy Technology Data Exchange (ETDEWEB)

    Cordiner, Martin A.; Charnley, Steven B.; Wirstroem, Eva S. [Astrochemistry Laboratory and Goddard Center for Astrobiology, NASA Goddard Space Flight Center, Greenbelt, MD 20770 (United States); Smith, Robert G., E-mail: martin.cordiner@nasa.gov [School of Physical, Environmental, and Mathematical Sciences, University of New South Wales, Australian Defence Force Academy, Canberra, ACT 2600 (Australia)

    2012-01-10

    Observations are presented of emission lines from organic molecules at frequencies 32-50 GHz in the vicinity of Chamaeleon MMS1. This chemically rich dense cloud core harbors an extremely young, very low luminosity protostellar object and is a candidate first hydrostatic core. Column densities are derived and emission maps are presented for species including polyynes, cyanopolyynes, sulphuretted carbon chains, and methanol. The polyyne emission peak lies about 5000 AU from the protostar, whereas methanol peaks about 15,000 AU away. Averaged over the telescope beam, the molecular hydrogen number density is calculated to be 10{sup 6} cm{sup -3} and the gas kinetic temperature is in the range 5-7 K. The abundances of long carbon chains are very large and are indicative of a non-equilibrium carbon chemistry; C{sub 6}H and HC{sub 7}N column densities are 5.9{sup +2.9}{sub -1.3} Multiplication-Sign 10{sup 11} cm{sup -2} and 3.3{sup +8.0}{sub -1.5} Multiplication-Sign 10{sup 12} cm{sup -2}, respectively, which are similar to the values found in the most carbon-chain-rich protostars and prestellar cores known, and are unusually large for star-forming gas. Column density upper limits were obtained for the carbon-chain anions C{sub 4}H{sup -} and C{sub 6}H{sup -}, with anion-to-neutral ratios [C{sub 4}H{sup -}]/[C{sub 4}H] < 0.02% and [C{sub 6}H{sup -}]/[C{sub 6}H] < 10%, consistent with previous observations in interstellar clouds and low-mass protostars. Deuterated HC{sub 3}N and c-C{sub 3}H{sub 2} were detected. The [DC{sub 3}N]/[HC{sub 3}N] ratio of approximately 4% is consistent with the value typically found in cold interstellar gas.

  2. Effects of body mass index on foot posture alignment and core stability in a healthy adult population.

    Science.gov (United States)

    AlAbdulwahab, Sami S; Kachanathu, Shaji John

    2016-06-01

    Foot biomechanics and core stability (CS) play significant roles in the quality of standing and walking. Minor alterations in body composition may influence base support or CS strategies. The aim of this study was to investigate the effect of the body mass index (BMI) on the foot posture index (FPI) and CS in a healthy adult population. A total of 39 healthy adult subjects with a mean age of 24.3±6.4 years and over-weight BMI values between 25 and 29.9 kg/m2 (27.43±6.1 kg/m2) participated in this study. Foot biomechanics were analyzed using the FPI. CS was assessed using a plank test with a time-to-failure trial. The Spearman correlation coefficient indicated a significant correlation between BMI and both the FPI (r=0.504, P=0.001) and CS (r= -0.34, P=0.036). Present study concluded that an overweight BMI influences foot posture alignment and body stability. Consequently, BMI should be considered during rehabilitation management for lower extremity injuries and body balance.

  3. Neutrino-driven supernova of a low-mass iron-core progenitor boosted by three-dimensional turbulent convection

    CERN Document Server

    Melson, Tobias; Marek, Andreas

    2015-01-01

    We present the first successful simulation of a neutrino-driven supernova explosion in three dimensions (3D), using the Prometheus-Vertex code with an axis-free Yin-Yang grid and a sophisticated treatment of three-flavor, energy-dependent neutrino transport. The progenitor is a non-rotating, zero-metallicity 9.6 Msun star with an iron core. While in spherical symmetry outward shock acceleration sets in later than 300 ms after bounce, a successful explosion starts at ~130 ms post-bounce in two dimensions (2D). The 3D model explodes at about the same time but with faster shock expansion than in 2D and a more quickly increasing and roughly 10 percent higher explosion energy. The more favorable explosion conditions in 3D are explained by lower temperatures and thus reduced neutrino emission in the cooling layer below the gain radius. This moves the gain radius inward and leads to a bigger mass in the gain layer, whose larger recombination energy boosts the explosion energy in 3D. These differences are caused by l...

  4. The hot core towards the intermediate mass protostar NGC7129 FIRS 2: Chemical similarities with Orion KL

    CERN Document Server

    Fuente, A; Caselli, P; McCoey, C; Johnstone, D; Fich, M; van Kempen, T; Palau, Aina; Yildiz, U A; Tercero, B; López, A

    2014-01-01

    NGC 7129 FIRS 2 (hereafter FIRS 2) is an intermediate-mass (2 to 8 Msun) protostar located at a distance of 1250 pc. High spatial resolution observations are required to resolve the hot core at its center. We present a molecular survey from 218200 MHz to 221800 MHz carried out with the IRAM Plateau de Bure Interferometer. These observations were complemented with a long integration single-dish spectrum taken with the IRAM 30m telescope. We used a Local Thermodynamic Equilibrium (LTE) single temperature code to model the whole dataset. The interferometric spectrum is crowded with a total of ~300 lines from which a few dozens remain unidentified yet. The spectrum has been modeled with a total of 20 species and their isomers, isotopologues and deuterated compounds. Complex molecules like methyl formate (CH3OCHO), ethanol (CH3CH2OH), glycolaldehyde (CH2OHCHO), acetone (CH3COCH3), dimethyl ether (CH3OCH3), ethyl cyanide (CH3CH2CN) and the aGg' conformer of ethylene glycol (aGg'-(CH2OH)_2) are among the detected sp...

  5. Prospective evaluation of new 22 gauge endoscopic ultrasound core needle using capillary sampling with stylet slow-pull technique for intra-abdominal solid masses.

    Science.gov (United States)

    Paik, Woo Hyun; Park, Yangsoon; Park, Do Hyun; Hong, Seung-Mo; Lee, Byung Uk; Choi, Jun-Ho; Lee, Sang Soo; Seo, Dong-Wan; Lee, Sung Koo; Kim, Myung-Hwan

    2015-03-01

    The aim of this study was to evaluate the adequacy and diagnostic yield of the histologic core obtained with a 22 G endoscopic ultrasound histology needle using capillary sampling with stylet slow-pull technique without on-site cytopathologist. No standard technique for new EUS histology needle has been established. A total of 125 consecutive patients with intra-abdominal solid masses were enrolled prospectively between October 2011 and March 2013. EUS-guided fine needle biopsy (EUS-FNB) with a 22 G histology needle using capillary sampling with stylet slow-pull technique was performed. A total of 133 EUS-FNB procedures targeting the pancreas, lymph node, retroperitoneal mass, ampulla of Vater, gallbladder, common bile duct, duodenum, and liver were performed in 125 patients. EUS-FNB was technically feasible in all cases, and a visible core was obtained in 128 cases (96%). Histologic core specimens suitable for pathologic assessment were reported in 111 cases (83%). There were no procedure-related adverse events. According to the determinants of malignancy with EUS-FNB, the sensitivity, specificity, positive and negative predictive values, and accuracy were 85%, 98%, 99%, 77%, and 89%, respectively. In addition, histologic architecture with or without immunohistochemical staining of the core biopsy specimens was useful for pathologic confirmation in 101 cases (76%). A 22 G EUS-FNB using capillary sampling with stylet slow-pull technique showed a high diagnostic yield and histologic core acquisition for the histologic diagnosis of various intra-abdominal masses without an on-site cytopathologist. Furthermore, a histologic core with or without immunohistochemical staining was helpful for clinical decision making in 76% of the intra-abdominal solid masses.

  6. Mass Spectrometry Data Collection in Parallel at Multiple Core Facilities Operating TripleTOF 5600 and Orbitrap Elite/Velos Pro/Q Exactive Mass Spectrometers

    Science.gov (United States)

    Jones, K.; Kim, K.; Patel, B.; Kelsen, S.; Braverman, A.; Swinton, D.; Gafken, P.; Jones, L.; Lane, W.; Neveu, J.; Leung, H.; Shaffer, S.; Leszyk, J.; Stanley, B.; Fox, T.; Stanley, A.; Yeung, Anthony

    2013-01-01

    Proteomic research can benefit from simultaneous access to multiple cutting-edge mass spectrometers. 18 core facilities responded to our investigators seeking service through the ABRF Discussion Forum. Five of the facilities selected completed four plasma proteomics experiments as routine fee-for-service. Each biological experiment entailed an iTRAQ 4-plex proteome comparison of immunodepleted plasma provided as 30 labeled-peptide fractions. Identical samples were analyzed by two AB SCIEX TripleTOF 5600 and three Thermo Orbitrap (Elite/Velos Pro/Q Exactive) instruments. 480 LC-MS/MS runs delivered >250 GB of data over two months. We compare herein routine service analyses of three peptide fractions of different peptide abundance. Data files from each instrument were studied to develop optimal analysis parameters to compare with default parameters in Mascot Distiller 2.4, ProteinPilot 4.5 beta, AB Sciex MS Data Converter 1.3 beta, and Proteome Discover 1.3. Peak-picking for TripleTOFs was best by ProteinPilot 4.5 beta while Mascot Distiller and Proteome Discoverer were comparable for the Orbitraps. We compared protein identification and quantitation in SwissProt 2012_07 database by Mascot Server 2.4.01 versus ProteinPilot. By all search methods, more proteins, up to two fold, were identified using the Q Exactive than others. Q Exactive excelled also at the number of unique significant peptide ion sequences. However, software-dependent impact on subsequent interpretation, due to peptide modifications, can be critical. These findings may have special implications for iTRAQ plasma proteomics. For the low abundance peptide ions, the slope of the dynamic range drop-off in the plasma proteome is uniquely sharp compared with cell lysates. Our study provides data for testable improvements in the operation of these mass spectrometers. More importantly, we have demonstrated a new affordable expedient workflow for investigators to perform proteomic experiments through the ABRF

  7. Tensile properties of V-(4-15)Cr-5Ti alloys irradiated at 400{degrees}C in the HFIR

    Energy Technology Data Exchange (ETDEWEB)

    Chung, H.M.; Nowicki, L.; Smith, D.L. [Argonne National Lab., IL (United States)

    1996-10-01

    V-(4-15)Cr-5Ti alloys were irradiated in a helium environment to {approx}10 dpa at {approx}400{degrees}C in the High Flux Isotope Reactor (HFIR). This report presents results of postirradiation tests of tensile properties of V-4Cr-4Ti, V-8Cr-6Ti, V-10Cr-5Ti, and V-15Cr-5Ti. Despite concerns on the effects of transmutation of vanadium to Cr and impurity pickup from the helium environment, all of the alloys exhibited ductile tensile behavior. However, the alloys exhibited ductilities somewhat lower than those of the specimens irradiated to a similar dose and at a similar temperature in an Li environment in fast reactors. Uniform plastic strain in the V-Cr-(4-5)Ti alloys decreased monotonically with increasing Cr content.

  8. Seismic hazard evaluation for the high-flux isotope reactor (HFIR) Oak Ridge National Laboratory, Oak Ridge, Tennessee

    Energy Technology Data Exchange (ETDEWEB)

    McGuire, R.K.; Toro, G.R. (Risk Engineering, Inc., Golden, CO (United States))

    1991-09-01

    This study investigates the probabilistic hazard of earthquake-induced ground shaking at the HFIR facility, Oak Ridge, Tennessee. These results will be used to calculate plant response and potential effects in a Probabilistic Risk Assessment (PRA). For this purpose, several guidelines apply to this work. First, both the frequency of exceedance and the uncertainty in frequency of exceedance of various ground motion levels must be represented. These are required by the PRA so that the frequency and uncertainty of various possible plant states can be expressed. Second, there is a deliberate attempt to provide an unbiased distribution of frequencies of exceedance, i.e. to present results that are neither conservative nor unconservative. This is consistent with the goals of a PRA, to provide unbiased estimates of plant effects from which appropriate decisions (for instance about evaluating existing levels of seismic design) can be reached. Recent intensive studies of seismic hazard in the central and eastern United States (CEUS) have been completed by the Electric Power Research Institute (EPRI). These studies represent major efforts to characterize the seismic hazard for nuclear power plants in the CEUS, and use the most recent, up-to-date understandings of seismicity and ground motion relations for the region. With these studies as a resource, the current effort relies exclusively on the seismicity and ground motion assumptions therein to formulate seismic hazard curves for the HFIR facility. The interpretation of these studies to derive seismic hazard curves in a format suitable for input to a PRA is described in this report. 29 refs., 40 figs., 22 tabs.

  9. Diagnostic impact of color Doppler ultrasound-guided core biopsy on fine-needle aspiration of anterior mediastinal masses.

    Science.gov (United States)

    Chen, Hung-Jen; Liao, Wei-Chih; Liang, Shinn-Jye; Li, Chia-Hsiang; Tu, Chih-Yen; Hsu, Wu-Huei

    2014-12-01

    Although lymphoma and thymoma are common etiologies of anterior mediastinal masses (AMMs), smaller percentages and numbers of patients with these diseases have been enrolled in previous ultrasound-guided biopsy studies. To date, there has been no study of color Doppler sonographic features to support the differentiation of AMMs. For this retrospective cohort study, a search of the database of the China Medical University Hospital using the clinical coding "ultrasound-guided biopsy" was conducted for the period December 2003 to February 2013. We selected patients diagnosed with AMMs (not cysts) using radiographic records. This search yielded a list of 80 cases. Real-time ultrasound-guided core needle biopsy (CNB) was performed in all but 5 patients without a sufficient safety range. In 89% (67/75) of these ultrasound-guided CNB cases, the diagnostic accuracy achieved subclassification. Fine-needle aspiration cytology achieved subclassification in only 10% of cases. On color Doppler sonography, 71% of lymphomas were characterized as "rich vascular with central/crisscross collocations" and 29% as "avascular or localized/scattered peripheral vessels." However, decreased proportions of "rich vascular with central/crisscross collocations" were found in lung cancer (4% [1/23], odds ratio = 0.018, 95% confidence interval: 0.002-0.154, p Fine-needle aspiration cytology itself cannot aid in the diagnosis. Color Doppler sonographic evaluation of AMMs followed by real-time CNB is a more efficient method. Copyright © 2014 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  10. The negative predictive value of ultrasound-guided 14-gauge core needle biopsy of breast masses: a validation study of 339 cases.

    Science.gov (United States)

    Zhang, Charlie; Lewis, Darrell R; Nasute, Paola; Hayes, Malcolm; Warren, Linda J; Gordon, Paula B

    2012-10-31

    To determine the negative predictive value of sonographically guided 14-gauge core needle biopsy of breast masses, with detailed analysis of any false-negative cases. We reviewed 669 cases of sonographically guided 14-gauge core needle biopsies that had benign pathologic findings. Given a benign pathology on core biopsy, true-negatives had either benign pathology on surgical excision or at least 2 years of stable imaging and/or clinical follow-up; false-negatives had malignant histology on surgical excision. Follow-up was available for 339 breast lesions; 117 were confirmed to be benign via surgical excision, and 220 were stable after 2 years or more of imaging or clinical follow-up (mean follow-up time 33.1 months, range 24-64 months). The negative predictive value was determined to be 99.4%. There were 2 false-negative cases, giving a false-negative rate of 0.1%. There was no delay in diagnosis in either case because the radiologist noted discordance between imaging and core biopsy pathology, and recommended surgical excision despite the benign core biopsy pathology. Sonographically guided 14-gauge core needle biopsy provides a high negative predictive value in assessing breast lesions. Radiologic/pathologic correlation should be performed to avoid delay in the diagnosis of carcinoma.

  11. Assessment of mass fraction and melting temperature for the application of limestone concrete and siliceous concrete to nuclear reactor basemat considering molten core-concrete interaction

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ho Jae; Kim, Do Gyeum [Korea Institute of Civil Engineering and Building Technology, Goyang (Korea, Republic of); Cho, Jae Leon [Korea Hydro and Nuclear Power Co., Ulsan (Korea, Republic of); Yoon, Eui Sik [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of); Cho, Myung Suk [Korea Hydro and Nuclear Power Co., Central Research Institute, Daejeon (Korea, Republic of)

    2016-04-15

    Severe accident scenarios in nuclear reactors, such as nuclear meltdown, reveal that an extremely hot molten core may fall into the nuclear reactor cavity and seriously affect the safety of the nuclear containment vessel due to the chain reaction caused by the reaction between the molten core and concrete. This paper reports on research focused on the type and amount of vapor produced during the reaction between a high-temperature molten core and concrete, as well as on the erosion rate of concrete and the heat transfer characteristics at its vicinity. This study identifies the mass fraction and melting temperature as the most influential properties of concrete necessary for a safety analysis conducted in relation to the thermal interaction between the molten core and the basemat concrete. The types of concrete that are actually used in nuclear reactor cavities were investigated. The H2O content in concrete required for the computation of the relative amount of gases generated by the chemical reaction of the vapor, the quantity of CO2 necessary for computing the cooling speed of the molten core, and the melting temperature of concrete are evaluated experimentally for the molten core-concrete interaction analysis.

  12. The accretion of solar material onto white dwarfs: No mixing with core material implies that the mass of the white dwarf is increasing

    Directory of Open Access Journals (Sweden)

    Sumner Starrfield

    2014-02-01

    Full Text Available Cataclysmic Variables (CVs are close binary star systems with one component a white dwarf (WD and the other a larger cooler star that fills its Roche Lobe. The cooler star is losing mass through the inner Lagrangian point of the binary and some unknown fraction of this material is accreted by the WD. One consequence of the WDs accreting material, is the possibility that they are growing in mass and will eventually reach the Chandrasekhar Limit. This evolution could result in a Supernova Ia (SN Ia explosion and is designated the Single Degenerate Progenitor (SD scenario. This paper is concerned with the SD scenario for SN Ia progenitors. One problem with the single degenerate scenario is that it is generally assumed that the accreting material mixes with WD core material at some time during the accretion phase of evolution and, since the typical WD has a carbon-oxygen CO core, the mixing results in large amounts of carbon and oxygen being brought up into the accreted layers. The presence of enriched carbon causes enhanced nuclear fusion and a Classical Nova explosion. Both observations and theoretical studies of these explosions imply that more mass is ejected than is accreted. Thus, the WD in a Classical Nova system is losing mass and cannot be a SN Ia progenitor. However, the composition in the nuclear burning region is important and, in new calculations reported here, the consequences to the WD of no mixing of accreted material with core material have been investigated so that the material involved in the explosion has only a Solar composition. WDs with a large range in initial masses and mass accretion rates have been evolved. I find that once sufficient material has been accreted, nuclear burning occurs in all evolutionary sequences and continues until a thermonuclear runaway (TNR occurs and the WD either ejects a small amount of material or its radius grows to about 1012 cm and the evolution is ended. In all cases where mass ejection occurs

  13. Design Study for a Low-Enriched Uranium Core for the High Flux Isotope Reactor, Annual report for FY 2009

    Energy Technology Data Exchange (ETDEWEB)

    Chandler, David [ORNL; Freels, James D [ORNL; Ilas, Germina [ORNL; Miller, James Henry [ORNL; Primm, Trent [ORNL; Sease, John D [ORNL; Guida, Tracey [University of Pittsburgh; Jolly, Brian C [ORNL

    2010-02-01

    This report documents progress made during FY 2009 in studies of converting the High Flux Isotope Reactor (HFIR) from high enriched uranium (HEU) fuel to low enriched uranium (LEU) fuel. Conversion from HEU to LEU will require a change in fuel form from uranium oxide to a uranium-molybdenum alloy. With axial and radial grading of the fuel foil and an increase in reactor power to 100 MW, calculations indicate that the HFIR can be operated with LEU fuel with no degradation in reactor performance from the current level. Results of selected benchmark studies imply that calculations of LEU performance are accurate. Studies are reported of the application of a silicon coating to surrogates for spheres of uranium-molybdenum alloy. A discussion of difficulties with preparing a fuel specification for the uranium-molybdenum alloy is provided. A description of the progress in developing a finite element thermal hydraulics model of the LEU core is provided.

  14. Production of medical radioisotopes in the ORNL high flux isotope reactor (HFIR) for cancer treatment and arterial restenosis therapy after PICA

    Science.gov (United States)

    Knapp, F. F.; Beets, A. L.; Mirzadeh, S.; Alexander, C. W.; Hobbs, R. L.

    1999-01-01

    The High Flux Isotope Reactor ( HFIR) at the Oak Ridge National Laboratory ( ORNL) represents an important resource for the production of a wide variety of medical radioisotopes. First beginning operation in 1965, the high thermal neutron flux (2.5×1015 neutrons/cm2/sec at 85 MW) and versatile target irradiation and handling facilities provide the opportunity for production of a wide variety of neutron-rich medical radioisotopes of current interest for therapy. In addition to serving as a key production site for californium-252 and other transuranic elements, important examples of therapeutic radioisotopes which are currently routinely produced in the HFIR for distribution include dysprosium-166 (parent of holmium-166), rhenium-186, tin-117 m and tungsten-188 (parent of rhenium-188). The nine hydraulic tube ( HT) positions in the central high flux region permit the insertion and removal of targets at any time during the operating cycle (22-24 days) and have traditionally represented a major site for production of medical radioisotopes. To increase the irradiation capabilities of the HFIR, special target holders have recently been designed and fabricated which will be installed in the six Peripheral Target Positions ( PTP), which are also located in the high flux region. These positions are only accessible during reactor refueling and will be used for long-term irradiations, such as required for the production of tin-117 m and tungsten-188. Each of the PTP tubes will be capable of housing a maximum of eight HT targets, thus increasing the total maximum number of HT targets from the current nine, to a total of 57. In this paper the therapeutic use of reactor-produced radioisotopes for bone pain palliation and vascular brachytherapy and the therapeutic medical radioisotope production capabilities of the ORNL HFIR are briefly discussed.

  15. Evolution and nucleosynthesis of extremely metal-poor and metal-free low- and intermediate-mass stars II. s-process nucleosynthesis during the core He flash

    CERN Document Server

    Campbell, Simon W; Karakas, Amanda I

    2010-01-01

    Models of primordial and hyper-metal-poor stars with masses similar to the Sun experience an ingestion of protons into the hot core during the core helium flash phase at the end of their red giant branch evolution. This produces a concurrent secondary flash powered by hydrogen burning that gives rise to further nucleosynthesis in the core. We perform post-process nucleosynthesis calculations on a one-dimensional stellar evolution calculation of a star of 1 solar mass and metallicity [Fe/H] = -6.5 that suffers a proton ingestion episode. Our network includes 320 nuclear species and 2,366 reactions and treats mixing and burning simultaneously. The mixing and burning of protons into the hot convective core leads to the production of 13C, which then burns via the 13C(alpha,n)16O reaction releasing a large number of free neutrons. During the first two years of neutron production the neutron poison 14N abundance is low, allowing the prodigious production of heavy elements such as strontium, barium, and lead via slo...

  16. Neutron dosimetry, damage calculations, and helium measurements for the HFIR-MFE-60J-1 and MFE-330J-1 spectral tailoring experiments

    Energy Technology Data Exchange (ETDEWEB)

    Greenwood, L.R. [Pacific Northwest Laboratory, Richland, WA (United States); Baldwin, C.A. [Oak Ridge National Lab., TN (United States); Oliver, B.M.

    1995-04-01

    The objective is to provide dosimetry and damage analysis for fusion materials irradiation experiments. Neutron fluence measurements and radiation damage calculations are reported for the joint US -Japanese MFE-60J-1 and MFE-330J-1 experiments in the hafnium-lined removable beryllium (RB{sup *}) position of the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. These experiments were continuations of the ORR-6J and 7J irradiations performed in the Oak Ridge Research Reactor. The combination of irradiations was designed to tailor the neutron spectrum in order to achieve fusion reactor helium/dpa levels in stainless steel. These experiments produced maximum helium (appm)/dpa(displacement per atom) levels of 10.2 at 18.5 dpa for the ORR-6J and HFIR-MFE-60J-1 combination and 11.8 at 19.0 dpa for the ORR-7J and HFIR-MFE-330J-1 combination. A helium measurement in one JPCA sample was in good agreement with helium calculations.

  17. Investigation of the particle-core structure of odd-mass nuclei in the N sub p N sub n scheme

    Energy Technology Data Exchange (ETDEWEB)

    Bucurescu, D.; Cata, G.; Cutoiu, D.; Dragulescu, E.; Ivascu, M.; Zamfir, N.V. (Institutul Central de Fizica, Bucharest (Romania)); Gizon, A.; Gizon, J. (Grenoble-1 Univ., 38 (France). Inst. des Sciences Nucleaires)

    1989-10-19

    The N{sub p}N{sub n} scheme is applied to data related to collective band structures determined by the unique parity shell model orbitals in odd-A nuclei from the mass regions A{approx equal}80-100 and A{approx equal}130. Simple systematics are obtained which give a synthetic picture of the evolution of the particle-core coupling in these nuclear regions. (orig.).

  18. Reinvestigation of aminoacyl-tRNA synthetase core complex by affinity purification-mass spectrometry reveals TARSL2 as a potential member of the complex.

    Directory of Open Access Journals (Sweden)

    Kyutae Kim

    Full Text Available Twenty different aminoacyl-tRNA synthetases (ARSs link each amino acid to their cognate tRNAs. Individual ARSs are also associated with various non-canonical activities involved in neuronal diseases, cancer and autoimmune diseases. Among them, eight ARSs (D, EP, I, K, L, M, Q and RARS, together with three ARS-interacting multifunctional proteins (AIMPs, are currently known to assemble the multi-synthetase complex (MSC. However, the cellular function and global topology of MSC remain unclear. In order to understand the complex interaction within MSC, we conducted affinity purification-mass spectrometry (AP-MS using each of AIMP1, AIMP2 and KARS as a bait protein. Mass spectrometric data were funneled into SAINT software to distinguish true interactions from background contaminants. A total of 40, 134, 101 proteins in each bait scored over 0.9 of SAINT probability in HEK 293T cells. Complex-forming ARSs, such as DARS, EPRS, IARS, Kars, LARS, MARS, QARS and RARS, were constantly found to interact with each bait. Variants such as, AIMP2-DX2 and AIMP1 isoform 2 were found with specific peptides in KARS precipitates. Relative enrichment analysis of the mass spectrometric data demonstrated that TARSL2 (threonyl-tRNA synthetase like-2 was highly enriched with the ARS-core complex. The interaction was further confirmed by coimmunoprecipitation of TARSL2 with other ARS core-complex components. We suggest TARSL2 as a new component of ARS core-complex.

  19. Ultraviolet laser desorption/ionization mass spectrometry of single-core and multi-core polyaromatic hydrocarbons under variable conditions of collisional cooling: insights into the generation of molecular ions, fragments and oligomers.

    Science.gov (United States)

    Gámez, Francisco; Hortal, Ana R; Martínez-Haya, Bruno; Soltwisch, Jens; Dreisewerd, Klaus

    2014-11-01

    The ultraviolet laser desorption/ionization of polyaromatic hydrocarbons (PAHs) has been investigated under different background pressures of an inert gas (up to 1.2 mbar of N2) in the ion source of a hybrid, orthogonal-extracting time-of-flight mass spectrometer (oTOF-MS). The study includes an ensemble of six model PAHs with isolated single polyaromatic cores and four ones with multiple cross-linked aromatic and polyaromatic cores. In combination with a weak ion extraction field, the variation of the buffer gas pressure allowed to control the degree of collisional cooling of the desorbed PAHs and, thus, to modulate their decomposition into fragments. The dominant fragmentation channels observed are related to dehydrogenation of the PAHs, in most cases through the cleavage of even numbers of C-H bonds. Breakage of C-C bonds leading to the fragmentation of rings, side chains and core linkages is also observed, in particular, at low buffer gas pressures. The precise patterns of the combined fragmentation processes vary significantly between the PAHs. The highest abundances of molecular PAH ions and cleanest mass spectra were consistently obtained at the highest buffer gas pressure of 1.2 mbar. The effective quenching of the fragmentation pathways at this elevated pressure improves the sensitivity and data interpretation for analytical applications, although the fragmentation of side chains and of bonds between (poly)aromatic cores is not completely suppressed in all cases. Moreover, these results suggest that the detected fragments are generated through thermal equilibrium processes rather than as a result of rapid photolysis. This assumption is further corroborated by a laser desorption/ionization post-source decay analysis using an axial time-of-flight MS. In line with these findings, covalent oligomers of the PAHs, which are presumably formed by association of two or more dehydrogenated fragments, are detected with higher abundances at the lower buffer gas

  20. The influence of turbulence during magnetized core collapse and its consequences on low-mass star formation

    CERN Document Server

    Joos, Marc; Ciardi, Andrea; Fromang, Sebastien

    2013-01-01

    [Abridged] Theoretical and numerical studies of star formation have shown that magnetic field (B) has a strong influence on both disk formation and fragmentation; even a relatively low B can prevent these processes. However, very few studies investigated the combined effects of B and turbulence. We study the effects of turbulence in magnetized core collapse, focusing on the magnetic diffusion, the orientation of the angular momentum (J) of the protostellar core, and on its consequences on disk formation, fragmentation and outflows. We perform 3D, AMR, MHD simulations of magnetically supercritical collapsing dense cores of 5 Msun using the MHD code RAMSES. A turbulent velocity field is imposed as initial conditions, characterised by a Kolmogorov power spectrum. Different levels of turbulence and magnetization are investigated, as well as 3 realisations for the turbulent velocity field. Magnetic diffusion, orientation of the rotation axis with respect to B, transport of J, disk formation, fragmentation and outf...

  1. Similarity between the C18O (J=1-0) core mass function and the IMF in the S 140 region

    CERN Document Server

    Ikeda, Norio

    2011-01-01

    We present the results of C18O(J=1-0) mapping observations of a 20'x18' area in the Lynds 1204 molecular cloud associated with the Sharpless 2-140 (S140) H II region. The C18O cube (alpha-delta-vLSR) data shows that there are three clumps with sizes of \\sim 1 pc in the region. Two of them have peculiar red shifted velocity components at their edges, which can be interpreted as the results of the interaction between the cloud and the Cepheus Bubble. From the C18O cube data, the clumpfind identified 123 C18O cores, which have mean radius, velocity width in FWHM, and LTE mass of 0.36\\pm0.07 pc, 0.37\\pm0.09 km s-1, and 41\\pm29 Msun, respectively. All the cores in S140 are most likely to be gravitationally bound by considering the uncertainty in the C18O abundance. We derived a C18O core mass function (CMF), which shows a power-law-like behavior above a turnover at 30 Msun. The best-fit power-law index of -2.1\\pm0.2 is quite consistent with those of the IMF and the C18O CMF in the OMC-1 region by Ikeda & Kitam...

  2. High mass star formation in the IRAS 17233-3606 region: a new nearby and bright hot core in the southern sky

    CERN Document Server

    Leurini, S; Thorwirth, S; Wyrowski, F; Schilke, P; Menten, K M; Guesten, R; Zapata, L

    2008-01-01

    We present molecular line observations of the massive star forming region IRAS 17233-3606 aimed at studying the molecular core associated with the source. The observations were made using the Atacama Pathfinder Experiment telescope in the CO (3-2) and HCO^+ (4-3) transitions, and in the CH_3OH (6_K-5_K), (7_K-6_K) and CH_3CN (16_K-15_K) bands. For the CO(3-2) and HCO^+ (4-3) transitions, we obtained maps with a size of 70''\\times 70''. The typical angular resolution of the data is ~18''. Our observations reveal an exceptionally rich molecular spectrum, a signpost of hot core activity. Comparisons with two other prominent southern hot cores were made through observations in the same frequency setups. We also detected a bipolar outflow in CO (3-2) and HCO^+ (4-3) lines. Modelling reveals a hot core of size ~3'' and a temperature of 150 K in the IRAS17233-3606 region. The parameters of the molecular outflow are derived through the analysis of the CO (3-2) emission, and are typical of outflows driven by high-mass...

  3. Capsule fabrication for in-situ measurement of radiation induced electrical degradation (RIED) of ceramics in HFIR

    Energy Technology Data Exchange (ETDEWEB)

    Eatherly, W.S.; Heatherly, D.W.; Hurst, M.T.; Qualls, A.L. [and others

    1996-04-01

    A collaborative DOE/Monbusho series of irradiation experiments is being implemented to determine, in situ, the effects of irradiation on the electrical resistivity of ceramic materials. The first experiment, TRIST-ER1, has been designed to irradiate 15 Al{sub 2}O{sub 3} test specimens at 450{degrees}C in an RB position of the High Flux Isotope Reactor (HFIR). Each test specimen is located in a sealed vanadium subcapsule with instrumentation provided to each subcapsule to measure temperature and resistance, and to place a biasing voltage across the specimen. Twelve of the specimens will be biased with 200 V/mm across the sample at all times, while three will not be biased, but can be if so desired during the irradiation. The experiment design, component fabrication, and subcapsule assembly have been completed. A three cycle irradiation, to a fast neutron (E>0.1 MeV) fluence of about 3x10{sup 25}n/m{sup 2} ({approx}3 dpa in Al{sub 2}O{sub 3}), is expected to begin early in March 1996.

  4. Effect of boron on post irradiation tensile properties of reduced activation ferritic steel (F-82H) irradiated in HFIR

    Energy Technology Data Exchange (ETDEWEB)

    Shiba, Kiyoyuki; Suzuki, Masahide; Hishinuma, Akimichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Dept. of Materials Science and Engineering; Pawel, J.E. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

    1994-12-31

    Reduced activation ferritic/martensitic steel, F-82H (Fe-8Cr-2W-V-Ta), was irradiated in the High Flux Isotope Reactor (HFIR) to doses between 11 and 34 dpa at 400 and 500 C. Post irradiation tensile tests were performed at the nominal irradiation temperature in vacuum. Some specimens included {sup 10}B or natural boron (nB) to estimate the helium effect on tensile properties. Tensile properties including the 0.2% offset yield stress, the ultimate tensile strength, the uniform elongation and the total elongation were measured. The tensile properties were not dependent on helium content in specimens irradiated to 34 dpa, however {sup 10}B-doped specimens with the highest levels of helium showed slightly higher yield strength and less ductility than boron-free specimens. Strength appears to go through a peak, and ductility through a trough at about 11 dpa. The irradiation to more than 21 dpa reduced the strength and increased the elongation to the unirradiated levels. Ferritic steels are one of the candidate alloys for nuclear fusion reactors because of their good thermophysical properties, their superior swelling resistance, and the low corrosion rate in contact with potential breeder and coolant materials.

  5. Microstructural evolution of HFIR-irradiated low activation F82H and F82H-{sup 10}B steels

    Energy Technology Data Exchange (ETDEWEB)

    Wakai, E.; Shiba, K.; Sawai, T. [Japan Atomic Energy Research Inst. (Japan); Hashimoto, N.; Robertson, J.P.; Klueh, R.L. [Oak Ridge National Lab., TN (United States)

    1998-03-01

    Microstructures of reduced-activation F82H (8Cr-2W-0.2V-0.04Ta) and the F82H steels doped with {sup 10}B, irradiated at 250 and 300 C to 3 and 57 dpa in the High Flux Isotope Reactor (HFIR), were examined by TEM. In the F82H irradiated at 250 C to 3 dpa, dislocation loops, small unidentified defect clusters with a high number density, and a few MC precipitates were observed in the matrix. The defect microstructure after 300 C irradiation to 57 dpa is dominated by the loops, and the number density of loops was lower than that of the F82H-{sup 10}B steel. Cavities were observed in the F82H-{sup 10}B steels, but the swelling value is insignificant. Small particles of M{sub 6}C formed on the M{sub 23}C{sub 6} carbides that were present in both steels before the irradiation at 300 C to 57 dpa. A low number density of MC precipitate particles formed in the matrix during irradiation at 300 C to 57 dpa.

  6. MUSE observations of the lensing cluster SMACSJ2031.8-4036: new constraints on the mass distribution in the cluster core

    CERN Document Server

    Richard, J; Martinez, J; Bacon, R; Clement, B; Weilbacher, P; Soto, K; Wisotzki, L; Vernet, J; Pello, R; Schaye, J; Turner, M; Martinsson, T

    2014-01-01

    We present new observations of the lensing cluster SMACSJ2031.8-4036 obtained with the MUSE integral field spectrograph as part of its commissioning on the Very Large Telescope. By providing medium-resolution spectroscopy over the full 4750-9350 Angstroms domain and a 1x1 arcmin2 field of view, MUSE is ideally suited for identifying lensed galaxies in the cluster core, in particular multiple-imaged systems. We perform a redshift analysis of all sources in the datacube and identify a total of 12 systems ranging from $z=1.46$ to $z=6.4$, with all images of each system confirmed by a spectroscopic redshift. This allows us to accurately constrain the cluster mass profile in this region. We foresee that future MUSE observations of cluster cores should help us discover very faint Lyman-alpha emitters thanks to the strong magnification and the high sensitivity of this instrument.

  7. An Assessment of Southern Ocean Water Masses and Sea Ice During 1988-2007 in a Suite of Interannual CORE-II Simulations

    Science.gov (United States)

    Downes, Stephanie M.; Farneti, Riccardo; Uotila, Petteri; Griffies, Stephen M.; Marsland, Simon J.; Bailey, David; Behrens, Erik; Bentsen, Mats; Bi, Daohua; Biastoch, Arne; Canuto, Vittorio M.; Howard, Armando; Kelley, Maxwell; Leboissetier, Anthony

    2015-01-01

    We characterise the representation of the Southern Ocean water mass structure and sea ice within a suite of 15 global ocean-ice models run with the Coordinated Ocean-ice Reference Experiment Phase II (CORE-II) protocol. The main focus is the representation of the present (1988-2007) mode and intermediate waters, thus framing an analysis of winter and summer mixed layer depths; temperature, salinity, and potential vorticity structure; and temporal variability of sea ice distributions. We also consider the interannual variability over the same 20 year period. Comparisons are made between models as well as to observation-based analyses where available. The CORE-II models exhibit several biases relative to Southern Ocean observations, including an underestimation of the model mean mixed layer depths of mode and intermediate water masses in March (associated with greater ocean surface heat gain), and an overestimation in September (associated with greater high latitude ocean heat loss and a more northward winter sea-ice extent). In addition, the models have cold and fresh/warm and salty water column biases centred near 50 deg S. Over the 1988-2007 period, the CORE-II models consistently simulate spatially variable trends in sea-ice concentration, surface freshwater fluxes, mixed layer depths, and 200-700 m ocean heat content. In particular, sea-ice coverage around most of the Antarctic continental shelf is reduced, leading to a cooling and freshening of the near surface waters. The shoaling of the mixed layer is associated with increased surface buoyancy gain, except in the Pacific where sea ice is also influential. The models are in disagreement, despite the common CORE-II atmospheric state, in their spatial pattern of the 20-year trends in the mixed layer depth and sea-ice.

  8. A possible link between the power spectrum of interstellar filaments and the origin of the prestellar core mass function

    CERN Document Server

    Roy, A; Arzoumanian, D; Peretto, N; Palmeirim, P; Konyves, V; Schneider, N; Benedettini, M; Di Francesco, J; Elia, D; Hill, T; Ladjelate, B; Louvet, F; Motte, F; Pezzuto, S; Schisano, E; Shimajiri, Y; Spinoglio, L; Ward-Thompson, D; White, G

    2015-01-01

    Two major features of the prestellar CMF are: 1) a broad peak below 1 Msun, presumably corresponding to a mean gravitational fragmentation scale, and 2) a characteristic power-law slope, very similar to the Salpeter slope of the stellar initial mass function (IMF) at the high-mass end. While recent Herschel observations have shown that the peak of the prestellar CMF is close to the thermal Jeans mass in marginally supercritical filaments, the origin of the power-law tail of the CMF/IMF at the high-mass end is less clear. Inutsuka (2001) proposed a theoretical scenario in which the origin of the power-law tail can be understood as resulting from the growth of an initial spectrum of density perturbations seeded along the long axis of filaments by interstellar turbulence. Here, we report the statistical properties of the line-mass fluctuations of filaments in nearby molecular clouds observed with Herschel using a 1-D power spectrum analysis. The observed filament power spectra were fitted by a power-law function...

  9. FIRST MEASUREMENTS OF {sup 15}N FRACTIONATION IN N{sub 2}H{sup +} TOWARD HIGH-MASS STAR-FORMING CORES

    Energy Technology Data Exchange (ETDEWEB)

    Fontani, F. [INAF-Osservatorio Astrofisico di Arcetri, L.go E. Fermi 5, I-50125 Firenze (Italy); Caselli, P.; Bizzocchi, L. [Max Planck Institute for Extraterrestrial Physics, Giessenbachstrasse 1, D-85748 Garching (Germany); Palau, A. [Centro de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, P.O. Box 3-72, 58090 Morelia, Michoacán, México (Mexico); Ceccarelli, C. [Univ. Grenoble Alpes, IPAG, F-38000 Grenoble (France)

    2015-08-01

    We report on the first measurements of the isotopic ratio {sup 14}N/{sup 15}N in N{sub 2}H{sup +} toward a statistically significant sample of high-mass star-forming cores. The sources belong to the three main evolutionary categories of the high-mass star formation process: high-mass starless cores, high-mass protostellar objects, and ultracompact H ii regions. Simultaneous measurements of the {sup 14}N/{sup 15}N ratio in CN have been made. The {sup 14}N/{sup 15}N ratios derived from N{sub 2}H{sup +} show a large spread (from ∼180 up to ∼1300), while those derived from CN are in between the value measured in the terrestrial atmosphere (∼270) and that of the proto-solar nebula (∼440) for the large majority of the sources within the errors. However, this different spread might be due to the fact that the sources detected in the N{sub 2}H{sup +} isotopologues are more than those detected in the CN ones. The {sup 14}N/{sup 15}N ratio does not change significantly with the source evolutionary stage, which indicates that time seems to be irrelevant for the fractionation of nitrogen. We also find a possible anticorrelation between the {sup 14}N/{sup 15}N (as derived from N{sub 2}H{sup +}) and the H/D isotopic ratios. This suggests that {sup 15}N enrichment could not be linked to the parameters that cause D enrichment, in agreement with the prediction by recent chemical models. These models, however, are not able to reproduce the observed large spread in {sup 14}N/{sup 15}N, pointing out that some important routes of nitrogen fractionation could be still missing in the models.

  10. Clinical application of core needle biopsy for pancreatic head mass%胰头部肿块术中组织芯活检临床价值

    Institute of Scientific and Technical Information of China (English)

    夏菁; 陈坚; 徐天放

    2011-01-01

    目的 评价胰头部肿块术中组织芯活检的定性诊断价值.方法 对11 年间行胰头部肿块术中组织芯活检245 例患者的结果,结合手术后病理切片,进行比较和分析.结果 全组患者术中组织芯活检诊断结果示:胰头腺癌188 例(76.7%),慢性胰腺炎39 例(15.9%)、胰腺不典型增生8 例(3.3%)、胰腺神经内分泌肿瘤10 例(4.1%).有3 例(1.2%)假阴性的患者,无假阳性病例.穿刺活检敏感性(与术后病理诊断符合率)高达98.8%,特异性为100%.2 例(0.8%)发生并发症,其中1 例活检过程中因损伤血管导致胆总管出血,病理提示为腺癌,遂行胰十二指肠切除术;另1 例慢性胰腺炎行胆肠内引流术,穿刺后引发急性胰腺炎,经非手术治疗后痊愈.结论 胰头部肿块术中组织芯活检是判断胰头部肿块性质较为安全、有效而准确的方法,与术后病理切片诊断符合率极高,可以为手术决策提供可靠依据.%Objective To evaluate the clinical value of core needle biopsy in the qualitative diagnosis of pancreatic head mass. Methods A total of 245 Core needle biopsies were performed in patients with pancre-atic head mass during 11-year period. The histopathological diagnosis on core needle biopsy was then com-pared with that of excision biopsy. Results In all cases in whom core needle biopsy was the diagnostic pro-cedure, there were 188 cases of pancreatic head cancer (76.7%), 39 cases of chronic pancreatitis (15.9%), 8 cases of pancreatic dysplasia (3.3%), and 10 cases of pancreatic neuroendocrine tumor (4.1%); 3 cases (1.2%) were false negative, but the false positive rate was zero. The sensitivity of core needle biopsy was 98.8%, with a specificity of 100%. 2 cases (0.8%) had complications. One case complicated with bile duct bleeding due to the injury of blood vessel and this complication was treated with pancreaticoduodenectomy. Another case of chronic pancreatitis with biliary drainage complicated with acute

  11. The Accretion of Solar Material onto White Dwarfs: No Mixing with Core Material Implies that the Mass of the White Dwarf is Increasing

    CERN Document Server

    Starrfield, Sumner

    2015-01-01

    Cataclysmic Variables (CVs) are close binary star systems with one component an accreting white dwarf (WD) and the other a larger cooler star that fills its Roche Lobe. One consequence of the WDs accreting material, is the possibility that they are growing in mass and will eventually reach the Chandrasekhar Limit. This evolution could result in a Supernova Ia (SN Ia) explosion and is designated the Single Degenerate Progenitor (SD) scenario. One problem with the single degenerate scenario is that it is generally assumed that the accreting material mixes with WD core material at some time during the accretion phase of evolution and, since the typical WD has a carbon-oxygen (CO) core, the mixing results in large amounts of carbon and oxygen being brought up into the accreted layers. The presence of enriched carbon causes enhanced nuclear fusion and a Classical Nova (CN)explosion. Thus, the WD in a Classical Nova system is decreasing in mass and cannot be a SN Ia progenitor. In new calculations reported here, th...

  12. Mass-dependent and mass-independent variations in the isotope composition of mercury in a sediment core from a lake polluted by emissions from the combustion of coal

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, Togwell A., E-mail: t.a.jackson@ec.gc.ca; Muir, Derek C.G.

    2012-02-15

    A dated sediment core from a lake polluted with mercury (Hg), other heavy metals, and arsenic (As) from coal-burning power plants was analysed to test the hypothesis that power plant emissions have distinctive Hg isotope signatures which may be preserved in sediments but are altered by natural processes. Coal and fly ash were also analysed. The research yielded evidence for mass-dependent and mass-independent fractionation of Hg isotopes (MDF and MIF, respectively) by combustion and flue gas reactions in the power plants and natural processes in the lake. Power plant pollution and earlier pollution attributable to domestic coal burning produced a characteristic isotope signature indicative of depletion in lighter isotopes by MDF and enrichment in {sup 199}Hg and {sup 201}Hg by MIF, suggesting loss of isotopically light gaseous Hg(0) and reactions of Hg with free radicals at the sources of pollution; but coal and fly ash data showed that combustion imparted a different signature to the ash, corroborating chemical evidence that reactive gaseous Hg(II), not particulate Hg(II), was the principal Hg fraction deposited in the lake. Moreover, the core data imply alteration of the anthropogenic isotope signature by microbially mediated MDF and MIF, with alteration of the microbial activities themselves by toxic effects of As and metals from the emissions. Effects of metals on isotope fractionation increased with the stability constants and ligand field stabilisation energies of metal complexes, suggesting inhibition of microbial enzymes and metal binding by microbial carrier molecules. The importance of fractionation by natural (possibly microbial) processes is also indicated by depletion in {sup 199}Hg and {sup 201}Hg owing to MIF in sediments predating local pollution. In brief, the isotope signature of the polluted sediment is probably the net result of abiotic reactions at the sources of pollution, microbial activities in the lake, and effects of toxic pollutants on

  13. Organic chemistry of low-mass star-forming cores I: 7 mm spectroscopy of Chamaeleon MMS1

    CERN Document Server

    Cordiner, Martin A; Wirström, Eva S; Smith, Robert G

    2011-01-01

    Observations are presented of emission lines from organic molecules at frequencies 32 - 50 GHz in the vicinity of Chamaeleon MMS1. This chemically-rich dense cloud core habours an extremely young, very low-luminosity protostellar object and is a candidate first hydrostatic core. Column densities are derived and emission maps are presented for species including polyynes, cyanopolyynes, sulphuretted carbon-chains and methanol. The polyyne emission peak lies about 5000 AU from the protostar, whereas methanol peaks about 15,000 AU away. Averaged over the telescope beam, the molecular hydrogen number density is calculated to be 10^6 cm^-3 and the gas kinetic temperature is in the range 5 - 7 K. The abundances of long carbon chains are very large, and are indicative of a non-equilibrium carbon chemistry; C6H and HC7N column densities are 5.9 (+2.9 -1.3) \\times 10^11 cm^-2 and 3.3 (+8.0 -1.5) \\times 10^12 cm^-2, respectively, which are similar to the values found in the most carbon-chain-rich protostars and prestell...

  14. Magnetic Fields in Star-Forming Molecular Clouds III. Submillimeter Polarimetry of Intermediate Mass Cores and Filaments in Orion B

    CERN Document Server

    Matthews, B C; Moriarty-Schieven, G H

    2002-01-01

    Using the imaging polarimeter for the Submillimeter Common User Bolometric Array at the James Clerk Maxwell Telescope, we have detected polarized thermal emission at 850 micron from dust toward three star-forming core systems in the Orion B molecular cloud: NGC 2071, NGC 2024 and LBS 23N (HH 24). The polarization patterns are not indicative of those expected for magnetic fields dominated by a single field direction, and all exhibit diminished polarization percentages toward the highest intensity peaks. NGC 2024 has the most organized polarization pattern which is centered consistently along the length of a chain of 7 far-infrared sources. We have modeled NGC 2024 using a helical field geometry threading a curved filament and also as a magnetic field swept up by the ionization front of the expanding HII region. In the latter case, the field is bent by the dense ridge, which accounts for both the polarization pattern and existing measurements of the line-of-sight field strength toward the northern cores FIR 1 t...

  15. Embrittlement of reduced-activation ferritic/martensitic steels irradiated in HFIR at 300 deg. C and 400 deg. C

    Energy Technology Data Exchange (ETDEWEB)

    Klueh, R.L. E-mail: ku2@ornl.gov; Sokolov, M.A.; Shiba, K.; Miwa, Y.; Robertson, J.P

    2000-12-01

    Miniature tensile and Charpy specimens of four ferritic/martensitic steels were irradiated at 300 deg. C and 400 deg. C in the high flux isotope reactor (HFIR) to a maximum dose of {approx}12 dpa. The steels were standard F82H (F82H-Std), a modified F82H (F82H-Mod), ORNL 9Cr-2WVTa, and 9Cr-2WVTa-2Ni, the 9Cr-2WVTa containing 2% Ni to produce helium by (n,{alpha}) reactions with thermal neutrons. More helium was produced in the F82H-Std than the F82H-Mod because of the presence of boron. Irradiation embrittlement in the form of an increase in the ductile-brittle transition temperature ({delta}DBTT) and a decrease in the upper-shelf energy (USE) occurred for all the steels. The two F82H steels had similar {delta}DBTTs after irradiation at 300 deg. C, but after irradiation at 400 deg. C, the {delta}DBTT for F82H-Std was less than for F82H-Mod. Under these irradiation conditions, little effect of the extra helium in the F82H-Std could be discerned. Less embrittlement was observed for 9Cr-2WVTa steel irradiated at 400 deg. C than for the two F82H steels. The 9Cr-2WVTa-2Ni steel with {approx}115 appm He had a larger {delta}DBTT than the 9Cr-2WVTa with {approx}5 appm He, indicating a possible helium effect.

  16. New Planetary Systems from the Calan-Hertfordshire Extrasolar Planet Search and the Core Accretion Mass Limit

    CERN Document Server

    Jenkins, J S; Tuomi, M; Díaz, M; Cordero, J P; Aguayo, A; Pantoja, B; Arriagada, P; Mahu, R; Brahm, R; Rojo, P; Soto, M G; Ivanyuk, O; Yoma, N Becerra; Day-Jones, A C; Ruiz, M T; Pavlenko, Y V; Barnes, J R; Murgas, F; Pinfield, D J; Jones, M I; López-Morales, M; Shectman, S; Butler, R P; Minniti, D

    2016-01-01

    We report the discovery of eight new giant planets, and updated orbits for four known planets, orbiting dwarf and subgiant stars, using the CORALIE, HARPS, and MIKE instruments as part of the Calan-Hertfordshire Extrasolar Planet Search. We include radial velocity data prior- and post-2014 CORALIE upgrade and our Bayesian updating method returned a systematic offset of 19.2$\\pm$4.8 m/s between the two velocity sets for our stars. The planets have masses in the range 1.1-5.4M$_{\\rm{J}}$s, orbital periods from 40-2900 days, and eccentricities from 0.0-0.6. They include a double-planet system orbiting the most massive star in our sample (HD147873), two eccentric giant planets (HD128356$b$ and HD154672$b$), and a rare 14~Herculis analogue (HD224538$b$). We find that there is an over-abundance of Jupiter-mass objects compared to a simple power law fit to the mass function, with a steep increase in the planet frequency around 3M$_{\\rm{J}}$, reflecting the increased efficiency of planet formation towards lower masse...

  17. Large mass movements, probably earthquake triggered, in Lake Geneva off the city of Lausanne revealed by seismic and sediment coring data

    Science.gov (United States)

    Correia Demand, Jehanne; Marillier, François; Yrro, Blé; Kremer, Katrina; Girardclos, Stéphanie

    2013-04-01

    Recent seismic studies in the central part of Lake Geneva have revealed the presence a series of Holocene sedimentary layers with either well-organized reflections or with chaotic or transparent seismic character. While the former correspond to lacustrine sediments deposited as hemipelagic or turbidite layers, the latter are interpreted to be related to mass movements. One of these events has recently been identified in the lake off the city of Lausanne. The total volume of the mass flow deposits, the surface of the associated turbidite and the length of its failure scar show that it was a major slide event. To study this lacustrine slide, two types of seismic data were acquired. The first one was a multichannel system with a 15 inch3 water gun with a central frequency of 800 Hz and the second one was a 3.5 kHz single channel pinger. The data sets provide complementary data, because of their differing vertical resolution, respectively 0.5 m and 0.15 m. Some data were acquired with both systems along the same profiles for direct comparison. A depth-age relationship derived from a sediment core located above the main mass deposit yields an age for the mass movement deposit between 3488 and 3820 cal BP (2 sigma uncertainty). The failure scar that lies close to the lake north shore appears to be continuous over a distance of more than 7 km. However, the presence of two separated mass flow deposits associated with this scar suggests that there were in fact two simultaneous slides and not only one. This, together with the observation of another simultaneous mass movement on the lake south shore of the lake, suggests that the mass movements were triggered by an earthquake. The mass movements off the city of Lausanne are located over a major fault zone affecting the Mesozoic substratum under the Quaternary sediments. The fault zone which is related to the formation of the Alps is not known to be seismically active at present. However, conspicuous features within the

  18. Deep Near-Infrared Imaging of the rho Oph Cloud Core: Clues to the Origin of the Lowest-Mass Brown Dwarfs

    CERN Document Server

    Marsh, Kenneth A; Kirkpatrick, J Davy; Lowrance, Patrick J; Cutri, Roc M; Velusamy, Thangasamy

    2010-01-01

    A search for young substellar objects in the rho Oph cloud core region has been made using the deep-integration Combined Calibration Scan images of the 2MASS extended mission in J, H and Ks bands, and Spitzer IRAC images at 3.6, 4.5, 5.8 and 8.0 microns. The field of view of the combined observations was 1 deg x 9.3 arcmin, and the 5 sigma limiting magnitude at J was 20.5. Comparison of the observed SEDs with the predictions of the COND and DUSTY models, for an assumed age of 1 Myr, supports the identification of many of the sources with brown dwarfs, and enables the estimation of effective temperature, Teff. The cluster members are then readily distinguishable from background stars by their locations on a plot of flux density versus Teff. The range of estimated Teff extends down to ~ 750 K, suggesting the presence of objects of sub-Jupiter mass. The results also suggest that the mass function for the rho Oph cloud resembles that of the sigma Orionis cluster based on a recent study, with both rising towards l...

  19. Core biopsy needle versus standard aspiration needle for endoscopic ultrasound-guided sampling of solid pancreatic masses: a randomized parallel-group study.

    Science.gov (United States)

    Lee, Yun Nah; Moon, Jong Ho; Kim, Hee Kyung; Choi, Hyun Jong; Choi, Moon Han; Kim, Dong Choon; Lee, Tae Hoon; Cha, Sang-Woo; Cho, Young Deok; Park, Sang-Heum

    2014-12-01

    An endoscopic ultrasound (EUS)-guided fine needle biopsy (EUS-FNB) device using a core biopsy needle was developed to improve diagnostic accuracy by simultaneously obtaining cytological aspirates and histological core samples. We prospectively compared the diagnostic accuracy of EUS-FNB with standard EUS-guided fine needle aspiration (EUS-FNA) in patients with solid pancreatic masses. Between January 2012 and May 2013, consecutive patients with solid pancreatic masses were prospectively enrolled and randomized to undergo EUS-FNB using a core biopsy needle or EUS-FNA using a standard aspiration needle at a single tertiary center. The specimen was analyzed by onsite cytology, Papanicolaou-stain cytology, and histology. The main outcome measure was diagnostic accuracy for malignancy. The secondary outcome measures were: the median number of passes required to establish a diagnosis, the proportion of patients in whom the diagnosis was established with each pass, and complication rates. The overall accuracy of combining onsite cytology with Papanicolaou-stain cytology and histology was not significantly different for the FNB (n = 58) and FNA (n = 58) groups (98.3 % [95 %CI 94.9 % - 100 %] vs. 94.8 % [95 %CI 91.9 % - 100 %]; P = 0.671). Compared with FNA, FNB required a significantly lower median number of needle passes to establish a diagnosis (1.0 vs. 2.0; P < 0.001). On subgroup analysis of 111 patients with malignant lesions, the proportion of patients in whom malignancy was diagnosed on the first pass was significantly greater in the FNB group (72.7 % vs. 37.5 %; P < 0.001). The overall accuracy of FNB and FNA in patients with solid pancreatic masses was comparable; however, fewer passes were required to establish the diagnosis of malignancy using FNB.This study was registered on the UMIN Clinical Trial Registry (UMIN000014057). © Georg Thieme Verlag KG Stuttgart · New York.

  20. Single-particle inductively coupled plasma mass spectroscopy analysis of size and number concentration in mixtures of monometallic and bimetallic (core-shell) nanoparticles.

    Science.gov (United States)

    Merrifield, Ruth C; Stephan, Chady; Lead, Jamie R

    2017-01-01

    It is challenging to separate and measure the physical and chemical properties of monometallic and bimetallic engineered nanoparticles (NPs), especially when mixtures are similar in size and at low concentration. We report that single particle inductively coupled mass spectroscopy (SP-ICP-MS), alongside field flow fractionation (FFF), has allowed for the accurate measurement of size and particle number concentrations of mixed metallic nanoparticles (NPs) containing monometallic NPs of gold (Au) and silver (Ag) and a bimetallic core-shell structured NP (Au@Ag) of equivalent size. Two sets of these NPs were measured. The first contained only 60nm particles, where the Au@Ag NP had a 30nm core and 15nm shell to make a total diameter of 60nm. The second contained only 80nm particles (Au@Ag NP core particle of 50nm with a 15nm shell). FFF separation was used here as a sizing technique rather than a separation technique. It was used to confirm that suspensions containing either individual or mixtures of the Au 60nm, Ag 60nm and AuAg 60nm suspensions eluted together and were of the same size. Similarly, FFF was used to show that suspensions containing individual or mixtures of the equivalent 80nm, eluted together and were of the same size. Although the 60nm and 80nm suspensions did not elute at the same time they were not run together. SP-ICP-MS is then used to identify the size and concentration of the particles within the suspension. Successful separation of the NPs was effected and the limits of the instrument were obtained. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Mass spectrometry and photoelectron spectroscopy of o-, m-, and p-terphenyl cluster anions: the effect of molecular shape on molecular assembly and ion core character.

    Science.gov (United States)

    Mitsui, Masaaki; Ando, Naoto; Nakajima, Atsushi

    2008-06-26

    Mass spectrometry and photoelectron spectroscopy of o-, m-, and p-terphenyl cluster anions, (o-TP)n(-) (n = 2-100), (m-TP)n(-) (n = 2-100), and (p-TP)n(-) (n = 1-100), respectively, are conducted to investigate the effect of molecular shape on the molecular aggregation form and the resultant ion core character of the clusters. For (o-TP)n(-) and (m-TP)n(-), neither magic numbers nor discernible isomers are observed throughout the size range. Furthermore, their vertical detachment energies (VDEs) increase up to large n and depend linearly on n(-1/3), implying that they possess a three-dimensional (3D), highly reorganized structure encompassing a monomeric anion core. For (p-TP)n(-), in contrast, prominent magic numbers of n = 5, 7, 10, 12, and 14 are observed, and the VDEs show pronounced irregular shifts below n = 10, while they remain constant above n = 14 (isomer A). These results can be rationalized with two-dimensional (2D) orderings of p-TP molecules and different types of 2D shell closure at n = 7 and 14, the monomeric and multimeric anion core, respectively. Above n = 16, the new feature (isomer B) starts to appear at the higher binding side of isomer A, and it becomes dominant with n, while isomer A gradually disappears for larger sizes. In contrast to isomer A, the VDEs of isomer B continuously increase with the cluster size. This characteristic size evolution suggests that the transition to modified 2D aggregation forms from 2D ones occurs at around n = 20.

  2. Some features of the effect the pH value and the physicochemical properties of boric acid have on mass transfer in a VVER reactor's core

    Science.gov (United States)

    Gavrilov, A. V.; Kritskii, V. G.; Rodionov, Yu. A.; Berezina, I. G.

    2013-07-01

    Certain features of the effect of boric acid in the reactor coolant of nuclear power installations equipped with a VVER-440 reactor on mass transfer in the reactor core are considered. It is determined that formation of boric acid polyborate complexes begins under field conditions at a temperature of 300°C when the boric acid concentration is equal to around 0.065 mol/L (4 g/L). Operations for decontaminating the reactor coolant system entail a growth of corrosion product concentration in the coolant, which gives rise to formation of iron borates in the zones where subcooled boiling of coolant takes place and to the effect of axial offset anomalies. A model for simulating variation of pressure drop in a VVER-440 reactor's core that has invariable parameters during the entire fuel campaign is developed by additionally taking into account the concentrations of boric acid polyborate complexes and the quantity of corrosion products (Fe, Ni) represented by the ratio of their solubilities.

  3. Angular momentum redistribution by mixed modes in evolved low-mass stars. II. Spin-down of the core of red giants induced by mixed modes

    CERN Document Server

    Belkacem, K; Goupil, M J; Mosser, B; Sonoi, T; Ouazzani, R M; Dupret, M A; Mathis, S; Grosjean, M

    2015-01-01

    The detection of mixed modes in subgiants and red giants by the CoRoT and \\emph{Kepler} space-borne missions allows us to investigate the internal structure of evolved low-mass stars. In particular, the measurement of the mean core rotation rate as a function of the evolution places stringent constraints on the physical mechanisms responsible for the angular momentum redistribution in stars. It showed that the current stellar evolution codes including the modelling of rotation fail to reproduce the observations. An additional physical process that efficiently extracts angular momentum from the core is thus necessary. Our aim is to assess the ability of mixed modes to do this. To this end, we developed a formalism that provides a modelling of the wave fluxes in both the mean angular momentum and the mean energy equations in a companion paper. In this article, mode amplitudes are modelled based on recent asteroseismic observations, and a quantitative estimate of the angular momentum transfer is obtained. This i...

  4. Core shell stationary phases for a novel separation of triglycerides in plant oils by high performance liquid chromatography with electrospray-quadrupole-time of flight mass spectrometer.

    Science.gov (United States)

    La Nasa, Jacopo; Ghelardi, Elisa; Degano, Ilaria; Modugno, Francesca; Colombini, Maria Perla

    2013-09-20

    A new method for the analysis of triglycerides (TAGs) in vegetable oils was developed using a Poroshell 120 EC-C18 column (3.0 mm×50 mm, 2.7 μm) with a high resolution ESI-Q-ToF tandem mass spectrometer as detection system. We used an Agilent Poroshell column, which is characterized by a recently developed stationary phase based on non-porous core particles. The results highlighted the advantages of this column in terms of the dramatic improvement in the number of theoretical plates and in low column backpressure. The developed method enabled us to analyze complex mixtures of more than 40 TAGs within less than 25 min and with a low backpressure (lower than 100 bar), and represents the first application of a core-shell stationary phase in reverse phase HPLC using an ESI-Q-ToF as detection system. The method was optimized on standards of TAGs, validated and applied to several plant oils. By a quantitative point of view, the method showed a very good linearity (r(2)>0.999) in the range 0.1-2.4 μg/g; high intra- and inter-day precision both in terms of retention times (RSD%<0.04%) and peak areas (RSD%<0.3%). Limits of detection and quantitation were lower than 0.03 μg/g and 0.10 μg/g, respectively.

  5. Accuracy of Percutaneous Core Biopsy in the Diagnosis of Small Renal Masses (≤4.0 cm: A Meta-analysis

    Directory of Open Access Journals (Sweden)

    Qiqi He

    2015-02-01

    Full Text Available Objective To use meta-analysis to determine the accuracy of percutaneous core needle biopsy in the diagnosis of small renal masses (SMRs≤4.0 cm. Materials and Methods Studies were identified by searching PubMed, Embase, and the Cochrane Library database up to March 2013. Two of the authors independently assessed the study quality using QUADAS-2 tool and extracted data that met the inclusion criteria. The sensitivity, specificity, likelihood ratios, diagnostic odds ratio (DOR and also summary receiver operating characteristic (SROC curve were investigated and draw. Deek’s funnel plot was used to evaluate the publication bias. Result A total of 9 studies with 788 patients (803 biopsies were included. Failed biopsies without repeated or aborted from follow-up/surgery result were excluded (232 patients and 353 biopsies. For all cases, the pooled sensitivity was 94.0% (95% CI: 91.0%, 95.0%, the pooled positive likelihood was 22.57 (95% CI: 9.20-55.34, the pooled negative likelihood was 0.09 (95% CI: 0.06-0.13, the pooled DOR was 296.52(95% CI: 99. 42-884.38. The area under the curve of SROC analysis was 0.959±0.0254. Conclusion Imaging-guided percutaneous core needle biopsy of small renal masses (SMRs≤4.0 cm is highly accurate to malignant tumor diagnosis with unknown metastatic status and could be offered to some patients after clinic judgment prior to surgical intervention consideration.

  6. 坚持党的群众路线强化党的核心凝聚力%Uphold the Party's Mass Line to Strengthen Its Core Cohesion

    Institute of Scientific and Technical Information of China (English)

    朱建一

    2013-01-01

    Since the 18th of National Congress of the Communist Party of China ,the mass line is a basic task in our country under the new historical period to ensure China's social transformation smoothly .Along with the intensifying social conflicts , the frequent social conflict events ,and deteriorating party -mass relationship ,our party's core cohesion and the social cohesion declines ,and social stability and development is affected and impeded .Under the new historical period ,the construction of social cohesion is an important task of social transformation in our country .Only by deepening development of the party's mass line , close ties with the masses ,our party and the country's further development and prosperity can be ensured .%党的十八大以来,群众工作是我党在新的历史时期保障我国社会转型顺利进行的一项基础性工作。随着社会矛盾不断激化、社会冲突性事件频发、党群关系恶化,我党的核心凝聚力及社会凝聚力不断下滑,社会稳定和发展受到较大的影响和阻碍。新历史时期下,社会凝聚力建设是我国社会转型的重要任务。只有进一步深化发展党的群众路线,密切联系群众,才能确保我党和国家的进一步繁荣和发展。

  7. Calibrating convective-core overshooting with eclipsing binary systems. The case of low-mass main-sequence stars

    CERN Document Server

    Valle, G; Moroni, P G Prada; Degl'Innocenti, S

    2016-01-01

    In a robust statistical way, we quantify the uncertainty that affects the calibration of the overshooting efficiency parameter $\\beta$ that is owing to the uncertainty on the observational data in double-lined eclipsing binary systems. We also quantify the bias that is caused by the lack of constraints on the initial helium content and on the efficiencies of the superadiabatic convection and microscopic diffusion. We adopted a modified grid-based SCEPtER pipeline using as observational constraints the effective temperatures, [Fe/H], masses, and radii of the two stars. In a reference scenario of mild overshooting $\\beta = 0.2$ for the synthetic data, we found both large statistical uncertainties and biases on the estimated $\\beta$. For the first 80% of the MS evolution, $\\beta$ is biased and practically unconstrained in the whole explored range [0.0; 0.4]. In the last 5% of the MS the bias vanishes and the $1 \\sigma$ error is about 0.05. For synthetic data computed with $\\beta = 0.0$, the estimated $\\beta$ is ...

  8. Observations of different core water cluster ions Y-(H2O)n (Y = O2, HOx, NOx, COx) and magic number in atmospheric pressure negative corona discharge mass spectrometry.

    Science.gov (United States)

    Sekimoto, Kanako; Takayama, Mitsuo

    2011-01-01

    Reliable mass spectrometry data from large water clusters Y(-)(H(2)O)(n) with various negative core ions Y(-) such as O(2)(-), HO(-), HO(2)(-), NO(2)(-), NO(3)(-), NO(3)(-)(HNO(3))(2), CO(3)(-) and HCO(4)(-) have been obtained using atmospheric pressure negative corona discharge mass spectrometry. All the core Y(-) ions observed were ionic species that play a central role in tropospheric ion chemistry. These mass spectra exhibited discontinuities in ion peak intensity at certain size clusters Y(-)(H(2)O)(m) indicating specific thermochemical stability. Thus, Y(-)(H(2)O)(m) may correspond to the magic number or first hydrated shell in the cluster series Y(-)(H(2)O)(n). The high intensity discontinuity at HO(-)(H(2)O)(3) observed was the first mass spectrometric evidence for the specific stability of HO(-)(H(2)O)(3) as the first hydrated shell which Eigen postulated in 1964. The negative ion water clusters Y(-)(H(2)O)(n) observed in the mass spectra are most likely to be formed via core ion formation in the ambient discharge area (760 torr) and the growth of water clusters by adiabatic expansion in the vacuum region of the mass spectrometers (≈1 torr). The detailed mechanism of the formation of the different core water cluster ions Y(-)(H(2)O)(n) is described.

  9. The Next Generation Virgo Cluster Survey (NGVS). XIII. The Luminosity and Mass Function of Galaxies in the Core of the Virgo Cluster and the Contribution from Disrupted Satellites

    CERN Document Server

    Ferrarese, Laura; Sanchez-Janssen, Ruben; Roediger, Joel; McConnachie, Alan W; Durrell, Patrick R; MacArthur, Lauren A; Blakeslee, John P; Duc, Pierre-Alain; Boissier, S; Boselli, Alessandro; Courteau, Stephane; Cuillandre, Jean-Charles; Emsellem, Eric; Gwyn, S D J; Guhathakurta, Puragra; Jordan, Andres; Lancon, Ariane; Liu, Chengze; Mei, Simona; Mihos, J Christopher; Puzia, Thomas H; Taylor, James E; Zhang, Hongxin

    2016-01-01

    We present measurements of the galaxy luminosity and stellar mass function in a 3.71 deg$^2$ (0.3 Mpc$^2$) area in the core of the Virgo cluster, based on $ugriz$ data from the Next Generation Virgo Cluster Survey (NGVS). The galaxy sample consists of 352 objects brighter than $M_g=-9.13$ mag, the 50% completeness limit of the survey. Using a Bayesian analysis, we find a best-fit faint end slope of $\\alpha=-1.33 \\pm 0.02$ for the g-band luminosity function; consistent results are found for the stellar mass function as well as the luminosity function in the other four NGVS bandpasses. We discuss the implications for the faint-end slope of adding 92 ultra compact dwarfs galaxies (UCDs) -- previously compiled by the NGVS in this region -- to the galaxy sample, assuming that UCDs are the stripped remnants of nucleated dwarf galaxies. Under this assumption, the slope of the luminosity function (down to the UCD faint magnitude limit, $M_g = -9.6$ mag) increases dramatically, up to $\\alpha = -1.60 \\pm 0.06$ when cor...

  10. Computed tomography-guided percutaneous core needle biopsy for diagnosis of mediastinal mass lesions: Experience with 110 cases in two university hospitals in Isfahan, Iran

    Science.gov (United States)

    Rabbani, Masoud; Sarrami, Amir Hossein

    2016-01-01

    Background: Computed tomography-guided percutaneous core needle biopsy (PCNB) is a diagnostic technique for initial assessment of mediastinal mass lesions. This study was conducted to evaluate its diagnostic yield and its complication rate. Materials and Methods: We reviewed the records of CT-guided PCNB in 110 patients with mediastinal mass lesions performed in Kashani and Alzahra Hospitals, Isfahan, from 2006 to 2012. Gender, age at biopsy, size, and anatomic location of the lesion, number of passes, site of approach, complications, and final diagnosis were extracted. Results: Our series encompasses 52 (47.2%) females and 58 (52/7%) males with mean age of 41 ± 8 years. The most common site of involvement was the anterior mediastinum (91.8% of cases). An average of 3/5 passes per patient has been taken for tissue sampling. Parasternal site was the most frequent approach taken for PCNB (in 78.1% of cases). Diagnostic tissue was obtained in 99 (90%) biopsies while, in 11 (10%) cases, specimen materials were inadequate. Lymphoma (49.5%) and bronchogenic carcinoma (33.3%) were the most frequent lesions in our series. The overall complication rate was 17.2% from which 10.9% was pneumothorax, 5.4% was hemoptysis, and 0.9% was vasovagal reflex. Conclusion: CT-guided PCNB is a safe and reliable procedure that can provide a precise diagnosis for patients with both benign and malignant mediastinal masses, and it is considered the preferred first diagnostic procedure use for this purpose.

  11. A gas chromatography/pyrolysis/isotope ratio mass spectrometry system for high-precision deltaD measurements of atmospheric methane extracted from ice cores.

    Science.gov (United States)

    Bock, Michael; Schmitt, Jochen; Behrens, Melanie; Möller, Lars; Schneider, Robert; Sapart, Celia; Fischer, Hubertus

    2010-03-15

    Air enclosures in polar ice cores represent the only direct paleoatmospheric archive. Analysis of the entrapped air provides clues to the climate system of the past in decadal to centennial resolution. A wealth of information has been gained from measurements of concentrations of greenhouse gases; however, little is known about their isotopic composition. In particular, stable isotopologues (deltaD and delta(13)C) of methane (CH(4)) record valuable information on its global cycle as the different sources exhibit distinct carbon and hydrogen isotopic composition. However, CH(4) isotope analysis is limited by the large sample size required and the demanding analysis as high precision is required. Here we present a highly automated, high-precision online gas chromatography/pyrolysis/isotope ratio monitoring mass spectrometry (GC/P/irmMS) technique for the analysis of deltaD(CH(4)). It includes gas extraction from ice, preconcentration, gas chromatographic separation and pyrolysis of CH(4) from roughly 500 g of ice with CH(4) concentrations as low as 350 ppbv. Ice samples with approximately 40 mL air and only approximately 1 nmol CH(4) can be measured with a precision of 3.4 per thousand. The precision for 65 mL air samples with recent atmospheric concentration is 1.5 per thousand. The CH(4) concentration can be obtained along with isotope data which is crucial for reporting ice core data on matched time scales and enables us to detect flaws in the measurement procedure. Custom-made script-based processing of MS raw and peak data enhance the system's performance with respect to stability, peak size dependency, hence precision and accuracy and last but not least time requirement.

  12. Hot prominence detected in the core of a coronal mass ejection: Analysis of SOHO/UVCS Lα and SOHO/LASCO visible-light observations

    Science.gov (United States)

    Heinzel, P.; Susino, R.; Jejčič, S.; Bemporad, A.; Anzer, U.

    2016-05-01

    Context. The paper deals with the physics of erupting prominences in the core of coronal mass ejections (CME). Aims: We determine the physical parameters of an erupting prominence embedded in the core of a CME using SOHO/UVCS hydrogen Lα and Lβ lines and SOHO/LASCO visible light observations. In particular we analyze the CME event observed on August 2, 2000. We develop the non-LTE (NLTE; i.e. considering departures from the local thermodynamic equilibrium - LTE) spectral diagnostics based on Lα and visible light observations. Methods: Our method is based on 1D NLTE modeling of eruptive prominences and takes into account the effect of large flow velocities, which reach up to 300 km s-1 for the studied event (the so-called Doppler dimming). The NLTE radiative-transfer method can be used for both optically thin and thick prominence structures. We combine spectroscopic UVCS observations of an erupting prominence in the core of a CME with visible light images from LASCO-C2 in order to derive the geometrical parameters like projected thickness and velocity, together with the effective temperature and column density of electrons. These are then used to constrain our NLTE radiative transfer modeling which provides the kinetic temperature, microturbulent velocity, gas pressure, ionization degree, the line opacities, and the prominence effective thickness (geometrical filling factor). Results: Analysis was made for 69 observational points (spatial pixels) inside the whole erupting prominence. Roughly one-half of them show a non-negligible Lα optical thickness for flow velocity 300 km s-1 and about one-third for flow velocity 150 km s-1. All pixels with Lατ0 ≤ 0.3 have been considered for further analysis, which is presented in the form of statistical distributions (histograms) of various physical quantities such as the kinetic temperature, gas pressure, and electron density for two representative flow velocities (150 and 300 km s-1) and non-zero microturbulence. For

  13. Alteration of hyaloclastites in the HSDP 2 Phase 1 Drill Core: 2. Mass balance of the conversion of sideromelane to palagonite and chabazite

    Science.gov (United States)

    Walton, Anthony W.; Schiffman, Peter; MacPherson, G. L.

    2005-09-01

    The Hawaii Scientific Drilling Project 2 Phase 1 core permits study of each stage of alteration of basalt glass during burial because stages of the process are separated vertically. Previous work has shown that alteration of hyaloclastite occurs progressively. The latest stage observed in the Phase 1 core involves marginal replacement of sideromelane in shards with palagonite while simultaneously forming chabazite in pores. The basic reaction at this stage is sideromelane + components from pore waters = palagonite + chabazite + components to pore waters. Mass balance calculations show that Fe was virtually immobile in this process, being retained in palagonite. Na, Ca, Ba, P, Al, and Si were lost during palagonitization and not fully consumed in making chabazite. Mg was lost during palagonitization but retained elsewhere in smectite. K, Rb, and Sr were extracted from pore waters and enriched in the sum of the alteration products. The amount of enrichment depended upon the amount of chabazite present, which depended upon the porosity when chabazite formed. Ti, Y, U, Zr, Nb, REE, and Th were enriched in palagonite, compared to sideromelane, but were absent in chabazite. Mass balance of all phases for the entire alteration process (including earlier stages) was not possible because poorly consolidated samples do not yield accurate modal values of phases, trace element analysis of smectite was not possible, and exchange with lavas and intrusions in the succession cannot be evaluated. Calculations indicate that too little of major oxides, except Na2O, was released during palagonitization to account for the amount of smectite observed in hyaloclastites. The results of this study, and several others published in the literature, indicate that under various circumstances palagonitization will consume particular elements from pore fluid or release them to it. Such mobility implies that the hydrology of the particular system and the composition of the dissolved solids in the

  14. Effect of boric acid mass transfer on the accumulation thereof in a fuel core under emergency modes at NPPs with WMR

    Science.gov (United States)

    Morozov, A. V.; Sorokin, A. P.; Ragulin, S. V.; Pityk, A. V.; Sahipgareev, A. R.; Soshkina, A. S.; Shlepkin, A. S.

    2017-07-01

    Boric acid mass transfer processes in the reactor facilities with WMR are considered for the case of an emergency with breaking of the main circulation pipeline (MCP) and the operation of the passive safety systems, such as first-, second-, and third-stage accumulator tank systems, and a passive heat removal system (PHRS). Calculation results are presented for a change in the boric acid concentration in the fuel core (FC) of a water-moderated reactor (WMR) in the case of an emergency process. The calculations have been performed for different values of drop entrainment of boric acid from the reactor (0, 0.2, 2%). A substantial excess of the maximum concentration of boric acid has been found to occur 24 hours after an emergency event with a break of MCP. It is shown that increasing the droplet entrainment of boric acid causes the crystallization and accumulation thereof in the FC to become slower. The mass of boric acid deposits on the elements of internals is determined depending on the values of drop entrainment. These results allow one to draw a conclusion concerning the possibility of accumulation and crystallization of boric acid in the FC, because the latter event could lead to a blocking of the flow cross section and disturbance in the heat removal from fuel elements. A review of available literature data concerning the thermal properties of boric acid solution (density, viscosity, thermal conductivity) is presented. It is found that the available data are of quite a general character, but it does not cover the entire range of parameters (temperature, pressure, acid concentrations) inherent in a possible emergency situation at nuclear power plants with WMR. It is demonstrated that experimental study of boric acid drop entrainment at the parameters inherent in the emergency mode of WMR operation, as well as the studies of boric acid thermal properties in a wide range of concentrations, are required.

  15. Infall/Expansion Velocities in the Low-mass Dense Cores L492, L694-2, and L1521F: Dependence on Position and Molecular Tracer

    Science.gov (United States)

    Keown, Jared; Schnee, Scott; Bourke, Tyler L.; Di Francesco, James; Friesen, Rachel; Caselli, Paola; Myers, Philip; Williger, Gerard; Tafalla, Mario

    2016-12-01

    Although surveys of infall motions in dense cores have been carried out for years, few surveys have focused on mapping infall across cores using multiple spectral-line observations. To fill this gap, we present IRAM 30 m telescope maps of N2H+(1-0), DCO+(2-1), DCO+(3-2), and HCO+(3-2) emission toward two prestellar cores (L492 and L694-2) and one protostellar core (L1521F). We find that the measured infall velocity varies with position across each core and choice of molecular line, likely as a result of radial variations in core chemistry and dynamics. Line-of-sight infall speeds estimated from DCO+(2-1) line profiles can decrease by 40-50 m s-1 when observing at a radial offset ≥slant 0.04 pc from the core's dust continuum emission peak. Median infall speeds calculated from all observed positions across a core can also vary by as much as 65 m s-1, depending on the transition. These results show that while single-pointing, single-transition surveys of core infall velocities may be good indicators of whether a core is either contracting or expanding, the magnitude of the velocities they measure are significantly impacted by the choice of molecular line, proximity to the core center, and core evolutionary state.

  16. Determination of seven neonicotinoid insecticides in beeswax by liquid chromatography coupled to electrospray-mass spectrometry using a fused-core column.

    Science.gov (United States)

    Yáñez, Karen P; Bernal, José L; Nozal, María J; Martín, María T; Bernal, José

    2013-04-12

    A new method has been developed to measure seven neonicotinoid insecticides (acetamiprid, clothianidin, dinotefuran, imidacloprid, nitenpyram, thiacloprid and thiamethoxam) in beeswax using liquid chromatography (LC) coupled to electrospray ionization mass spectrometry (ESI-MS) detection. Beeswax was melted and diluted in an n-hexane/isopropanol (8:2, v/v) mixture. After this, liquid extraction with water was performed followed by a clean-up on diatomaceous material based cartridges. The compounds were eluted with acetone, and the resulting solution was evaporated until dry and reconstituted with a mixture of water and acetonitrile 50:50 (v/v). The separation of all compounds was achieved in less than 15 min using a C18 reverse-phase fused-core column (Kinetex C18, 150 mm × 4.6 mm i.d.) and a mobile phase composed of a mixture of 0.1% formic acid in water and acetonitrile in gradient elution mode at 0.5 mL/min. This method was fully validated in terms of selectivity, linearity, precision and recovery. Low limits of detection and quantification could be achieved for all analytes ranging from 0.4 to 2.3 μg/kg, and from 1.5 to 7.0 μg/kg, respectively. Finally, the proposed method was applied to an analysis of neonicotinoid residues in beeswax samples from apiaries located close to fruit orchards.

  17. Sulfur mass loading of the atmosphere from volcanic eruptions: Calibration of the ice core record on basis of sulfate aerosol deposition in polar regions from the 1982 El Chichon eruption

    Science.gov (United States)

    Sigurdsson, Haraldur; Laj, Paolo

    1990-01-01

    Major volcanic eruptions disperse large quantities of sulfur compound throughout the Earth's atmosphere. The sulfuric acid aerosols resulting from such eruptions are scavenged by snow within the polar regions and appear in polar ice cores as elevated acidity layers. Glacio-chemical studies of ice cores can, thus, provide a record of past volcanism, as well as the means for understanding the fate of volcanic sulfur in the atmosphere. The primary objectives of this project are to study the chemistry and physical properties of volcanic fallout in a Greenland Ice Core in order to evaluate the impact of the volcanic gases on the atmospheric chemistry and the total atmospheric mass of volcanic aerosols emitted by major volcanic eruptions. We propose to compare the ice core record to other atmospheric records performed during the last 10 years to investigate transport and deposition of volcanic materials.

  18. Infall/Expansion Velocities in the Low-Mass Dense Cores L492, L694-2, and L1521F: Dependence on Position and Molecular Tracer

    CERN Document Server

    Keown, Jared; Bourke, Tyler L; Di Francesco, James; Friesen, Rachel; Caselli, Paola; Myers, Philip; Williger, Gerard; Tafalla, Mario

    2016-01-01

    Although surveys of infall motions in dense cores have been carried out for years, few surveys have focused on mapping infall across cores using multiple spectral line observations. To fill this gap, we present IRAM 30-m Telescope maps of N2H+(1-0), DCO+(2-1), DCO+(3-2), and HCO+(3-2) emission towards two prestellar cores (L492 and L694-2) and one protostellar core (L1521F). We find that the measured infall velocity varies with position across each core and choice of molecular line, likely as a result of radial variations in core chemistry and dynamics. Line-of-sight infall speeds estimated from DCO+(2-1) line profiles can decrease by 40-50 m/s when observing at a radial offset >= 0.04 pc from the core's dust continuum emission peak. Median infall speeds calculated from all observed positions across a core can also vary by as much as 65 m/s depending on the transition. These results show that while single-pointing, single-transition surveys of core infall velocities may be good indicators of whether a core is...

  19. Computational investigation of longitudinal diffusion, eddy dispersion, and trans-particle mass transfer in bulk, random packings of core-shell particles with varied shell thickness and shell diffusion coefficient.

    Science.gov (United States)

    Daneyko, Anton; Hlushkou, Dzmitry; Baranau, Vasili; Khirevich, Siarhei; Seidel-Morgenstern, Andreas; Tallarek, Ulrich

    2015-08-14

    In recent years, chromatographic columns packed with core-shell particles have been widely used for efficient and fast separations at comparatively low operating pressure. However, the influence of the porous shell properties on the mass transfer kinetics in core-shell packings is still not fully understood. We report on results obtained with a modeling approach to simulate three-dimensional advective-diffusive transport in bulk random packings of monosized core-shell particles, covering a range of reduced mobile phase flow velocities from 0.5 up to 1000. The impact of the effective diffusivity of analyte molecules in the porous shell and the shell thickness on the resulting plate height was investigated. An extension of Giddings' theory of coupled eddy dispersion to account for retention of analyte molecules due to stagnant regions in porous shells with zero mobile phase flow velocity is presented. The plate height equation involving a modified eddy dispersion term excellently describes simulated data obtained for particle-packings with varied shell thickness and shell diffusion coefficient. It is confirmed that the model of trans-particle mass transfer resistance of core-shell particles by Kaczmarski and Guiochon [42] is applicable up to a constant factor. We analyze individual contributions to the plate height from different mass transfer mechanisms in dependence of the shell parameters. The simulations demonstrate that a reduction of plate height in packings of core-shell relative to fully porous particles arises mainly due to reduced trans-particle mass transfer resistance and transchannel eddy dispersion. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Prediction of Core-Annulus Solids Mass Transfer Coefficient in Gas-Solid Fluidized Bed Risers%气固循环流化床提升管环核区颗粒质量传递系数的估计

    Institute of Scientific and Technical Information of China (English)

    刘新华; 高士秋; 宋文立

    2005-01-01

    Based on analysis of energy dissipation in the core region of gas-solid fluidized bed risers, a simplified model for determination of core-annulus solids mass transfer coefficient was developed according to turbulent diffusion mechanism of particles. The simulation results are consistent with published experimental data. Core-annulus solids mass transfer coefficient decreases with increasing particle size, particle density and solids circulation rate,but generally increases with increasing superficial gas velocity and riser diameter. In the upper dilute region of gas-solid fluidized bed risers, core-annulus solids mass transfer coefficient was found to change little with the axial coordinate in the bed.

  1. Microstructural evolution of austenitic stainless steels irradiated to 17 dpa in spectrally tailored experiment of the ORR and HFIR at 400{degrees}C

    Energy Technology Data Exchange (ETDEWEB)

    Wakai, E.; Hashimoto, N.; Gibson, L.T. [Oak Ridge National Lab., TN (United States)] [and others

    1997-08-01

    The microstructural evolution of austenitic JPCA aged and solution annealed JPCA, 316R, C, K, and HP steels irradiated at 400{degrees}C in spectrally tailored experiments of the ORR and HFIR has been investigated. The helium generation rates were about 12-16 appm He/dpa on the average up to 17.3 dpa. The number densities and average diameters of dislocation loops in the steels have ranges of 3.3 x 10{sup 21} m{sup -3} and 15.2-26.3 nm, respectively, except for HP steel for which they are 1.1 x 10{sup 23} m{sup -3} and 8.0 nm. Precipitates are formed in all steels except for HP steel, and the number densities and average diameters have ranges of 5.2 x 10{sup 20} - 7.7 x 10{sup 21} m{sup -3} and 3.4- 19.3 nm, respectively. In the 216R, C, and K steels, the precipitates are also formed at grain boundaries, and the mean sizes of these are about 110, 50, and 50 nm, respectively. The number densities of cavities are about 1 x 10{sup 22} m{sup -3} in all the steels. The swelling is low in the steels which form the precipitates.

  2. Ice cores

    DEFF Research Database (Denmark)

    Svensson, Anders

    2014-01-01

    Ice cores from Antarctica, from Greenland, and from a number of smaller glaciers around the world yield a wealth of information on past climates and environments. Ice cores offer unique records on past temperatures, atmospheric composition (including greenhouse gases), volcanism, solar activity......, dustiness, and biomass burning, among others. In Antarctica, ice cores extend back more than 800,000 years before present (Jouzel et al. 2007), whereas. Greenland ice cores cover the last 130,000 years...

  3. Ice cores

    DEFF Research Database (Denmark)

    Svensson, Anders

    2014-01-01

    Ice cores from Antarctica, from Greenland, and from a number of smaller glaciers around the world yield a wealth of information on past climates and environments. Ice cores offer unique records on past temperatures, atmospheric composition (including greenhouse gases), volcanism, solar activity......, dustiness, and biomass burning, among others. In Antarctica, ice cores extend back more than 800,000 years before present (Jouzel et al. 2007), whereas. Greenland ice cores cover the last 130,000 years...

  4. Visual Feedback for Rover-based Coring

    Science.gov (United States)

    Backes, Paul; Helmick, Daniel; Bajracharya, Max

    2008-01-01

    Technology for coring from a low-mass rover has been developed to enable core sample acquisition where a planetary rover experiences moderate slip during the coring operation. A new stereo vision technique, Absolute Motion Visual Odometry, is used to measure rover slip during coring and the slip is accommodated through corresponding arm pose updating. Coring rate is controlled by feedback of themeasured force of the coring tool against the environment. Test results in the JPL Marsyard show for the first time that coring from a low-mass rover with slip is feasible.

  5. Revised ANL-reported tensile data for unirradiated and irradiated (FFTF, HFIR) V-Ti and V-Cr-Ti alloys

    Energy Technology Data Exchange (ETDEWEB)

    Billone, M.C. [Argonne National Lab., IL (United States)

    1998-03-01

    The tensile data for all unirradiated and irradiated vanadium alloys samples tested at Argonne National Laboratory (ANL) have been critically reviewed and, when necessary, revised. The review and revision are based on reanalyzing the original load-displacement strip chart recordings by a methodology consistent with current ASTM standards. For unirradiated alloys (162 samples), the revised values differ from the previous values as follows: {minus}11{+-}19 MPa ({minus}4{+-}6%) for yield strength (YS), {minus}3{+-}15 MPa ({minus}1{+-}3%) for ultimate tensile strength (UTS), {minus}5{+-}2% strain for uniform elongation (UE), and {minus}4{+-}2% strain for total elongation (TE). Of these changes, the decrease in {minus}1{+-}6 MPa (0{+-}1%) for UTS, {minus}5{+-}2% for UE, and {minus}4{+-}2% for TE. Of these changes, the decrease in UE values for alloys irradiated and tested at 400--435 C is the most significant. This decrease results from the proper subtraction of nongauge-length deformation from measured crosshead deformation. In previous analysis of the tensile curves, the nongauge-length deformation was not correctly determined and subtracted from the crosshead displacement. The previously reported and revised tensile values for unirradiated alloys (20--700 C) are tabulated in Appendix A. The revised tensile values for the FFTF-irradiated (400--600 C) and HFIR-irradiated (400 C) alloys are tabulated in Appendix B, along with the neutron damage and helium levels. Appendix C compares the revised values to the previously reported values for irradiated alloys. Appendix D contains previous and revised values for the tensile properties of unirradiated V-5Cr-5Ti (BL-63) alloy exposed to oxygen.

  6. Ductal carcinoma in situ diagnosed using an ultrasound-guided 14-gauge core needle biopsy of breast masses: can underestimation be predicted preoperatively?

    Directory of Open Access Journals (Sweden)

    Sung Hee Park

    2014-04-01

    Conclusion: We found a 30.4% rate of DCIS underestimation in breast masses based on a US-14G-CNB. The presence of abnormal lymph nodes as detected on axillary ultrasound may be useful to preoperatively predict underestimation.

  7. A comparison of embedded total task instruction in teaching behavioral chains to massed one-on-one instruction for students with intellectual disabilities: accessing general education settings and core academic content.

    Science.gov (United States)

    Jameson, J Matt; Walker, Ryan; Utley, Kristen; Maughan, Ryan

    2012-05-01

    This study is a comparison of the embedded instruction of behavioral chains with more traditional (one-on-one massed trials in special education setting) instructional procedures for teaching behavioral chains to students with significant cognitive disabilities. Although embedded instruction has emerged as a promising potential instructional procedure, no literature has examined the efficacy of embedded instructional procedures to teach more complex chained behaviors. To date, all research on embedding instruction in general education settings has focused on teaching discrete skills. This study compares instruction of embedded total task chains with more traditional (one-on-one massed trials in special education setting) instructional procedures for teaching behavioral chains. The chains targeted for instruction were selected by state core educational needs and functional skill development.

  8. Transformer core

    NARCIS (Netherlands)

    Mehendale, A.; Hagedoorn, Wouter; Lötters, Joost Conrad

    2010-01-01

    A transformer core includes a stack of a plurality of planar core plates of a magnetically permeable material, which plates each consist of a first and a second sub-part that together enclose at least one opening. The sub-parts can be fitted together via contact faces that are located on either side

  9. Transformer core

    NARCIS (Netherlands)

    Mehendale, A.; Hagedoorn, Wouter; Lötters, Joost Conrad

    2008-01-01

    A transformer core includes a stack of a plurality of planar core plates of a magnetically permeable material, which plates each consist of a first and a second sub-part that together enclose at least one opening. The sub-parts can be fitted together via contact faces that are located on either side

  10. Erratum: Progenitor-explosion connection and remnant birth masses for neutrino-driven supernovae of iron-core progenitors (2012, ApJ, 757, 69)

    CERN Document Server

    Ertl, Thomas; Janka, H -Thomas; Marek, Andreas; Arcones, Almudena

    2016-01-01

    An erroneous interpretation of the hydrodynamical results led to an incorrect determination of the fallback masses in Ugliano et al. (2012), which also (on a smaller level) affects the neutron star masses provided in that paper. This problem was already addressed and corrected in the follow-up works by Ertl et al. (2015) and Sukhbold et al. (2015). Therefore, the reader is advised to use the new data of the latter two publications. In the remaining text of this Erratum we present the differences of the old and new fallback results in detail and explain the origin of the mistake in the original analysis by Ugliano et al. (2012).

  11. Planetary Nebulae and their parent stellar populations. Tracing the mass assembly of M87 and Intracluster light in the Virgo cluster core

    CERN Document Server

    Arnaboldi, Magda; Gerhard, Ortwin

    2015-01-01

    The diffuse extended outer regions of galaxies are hard to study because they are faint, with typical surface brightness of 1% of the dark night sky. We can tackle this problem by using resolved star tracers which remain visible at large distances from the galaxy centres. This article describes the use of Planetary Nebulae as tracers and the calibration of their properties as indicators of the star formation history, mean age and metallicity of the parent stars in the Milky Way and Local Group galaxies . We then report on the results from a deep, extended, planetary nebulae survey in a 0.5 sqdeg region centred on the brightest cluster galaxy NGC 4486 (M87) in the Virgo cluster core, carried out with SuprimeCam@Subaru and FLAMES-GIRAFFE@VLT. Two PN populations are identified out to 150 kpc distance from the centre of M87. One population is associated with the M87 halo and the second one with the intracluster light in the Virgo cluster core. They have different line-of-sight velocity and spatial distributions, ...

  12. Planetary Nebulae and their parent stellar populations. Tracing the mass assembly of M87 and Intracluster light in the Virgo cluster core

    Science.gov (United States)

    Arnaboldi, Magda; Longobardi, Alessia; Gerhard, Ortwin

    2016-08-01

    The diffuse extended outer regions of galaxies are hard to study because they are faint, with typical surface brightness of 1% of the dark night sky. We can tackle this problem by using resolved star tracers which remain visible at large distances from the galaxy centers. This article describes the use of Planetary Nebulae as tracers and the calibration of their properties as indicators of the star formation history, mean age and metallicity of the parent stars in the Milky Way and Local Group galaxies. We then report on the results from a deep, extended, planetary nebulae survey in a 0.5 deg2 region centered on the brightest cluster galaxy NGC 4486 (M87) in the Virgo cluster core, carried out with SuprimeCam@Subaru and FLAMES-GIRAFFE@VLT. Two planetary nebulae populations are identified out to 150 kpc distance from the center of M87. One population is associated with the M87 halo and the second one with the intracluster light in the Virgo cluster core. They have different line-of-sight velocity and spatial distributions, as well as different planetary nebulae specific frequencies and luminosity functions. The intracluster planetary nebulae in the surveyed region correspond to a luminosity of four times the luminosity of the Large Magellanic Cloud. The M87 halo planetary nebulae trace an older, more metal-rich, parent stellar population. A substructure detected in the projected phase-space of the line-of-sight velocity vs. major axis distance for the M87 halo planetary nebulae provides evidence for the recent accretion event of a satellite galaxy with luminosity twice that of M33. The satellite stars were tidally stripped about 1 Gyr ago, and reached apocenter at a major axis distance of 60-90 kpc from the center of M87. The M87 halo is still growing significantly at the distances where the substructure is detected.

  13. Ice Cores

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Records of past temperature, precipitation, atmospheric trace gases, and other aspects of climate and environment derived from ice cores drilled on glaciers and ice...

  14. Core BPEL

    DEFF Research Database (Denmark)

    Hallwyl, Tim; Højsgaard, Espen

    extensions. Combined with the fact that the language definition does not provide a formal semantics, it is an arduous task to work formally with the language (e.g. to give an implementation). In this paper we identify a core subset of the language, called Core BPEL, which has fewer and simpler constructs......, does not allow omissions, and does not contain ignorable elements. We do so by identifying syntactic sugar, including default values, and ignorable elements in WS-BPEL. The analysis results in a translation from the full language to the core subset. Thus, we reduce the effort needed for working...... formally with WS-BPEL, as one, without loss of generality, need only consider the much simpler Core BPEL. This report may also be viewed as an addendum to the WS-BPEL standard specification, which clarifies the WS-BPEL syntax and presents the essential elements of the language in a more concise way...

  15. Core BPEL

    DEFF Research Database (Denmark)

    Hallwyl, Tim; Højsgaard, Espen

    extensions. Combined with the fact that the language definition does not provide a formal semantics, it is an arduous task to work formally with the language (e.g. to give an implementation). In this paper we identify a core subset of the language, called Core BPEL, which has fewer and simpler constructs......, does not allow omissions, and does not contain ignorable elements. We do so by identifying syntactic sugar, including default values, and ignorable elements in WS-BPEL. The analysis results in a translation from the full language to the core subset. Thus, we reduce the effort needed for working...... formally with WS-BPEL, as one, without loss of generality, need only consider the much simpler Core BPEL. This report may also be viewed as an addendum to the WS-BPEL standard specification, which clarifies the WS-BPEL syntax and presents the essential elements of the language in a more concise way...

  16. Core benefits

    National Research Council Canada - National Science Library

    Keith, Brian W

    2010-01-01

    This SPEC Kit explores the core employment benefits of retirement, and life, health, and other insurance -benefits that are typically decided by the parent institution and often have significant governmental regulation...

  17. Millimeter- and Submillimeter-Wave Observations of the OMC-2/3 Region; I. Dispersing and Rotating Core around an Intermediate-mass Protostar MMS 7

    CERN Document Server

    Takahashi, S; Takakuwa, S; Kawabe, R; Takahashi, Satoko; Saito, Masao; Takakuwa, Shigehisa; Kawabe, Ryohei

    2006-01-01

    We report the results of H13CO+(1-0), CO(1-0), and 3.3 mm dust continuum observations toward one of the strongest mm-wave sources in OMC-3, MMS 7, with the Nobeyama Millimeter Array (NMA) and the Nobeyama 45 m telescope. With the NMA, we detected centrally-condensed 3.3 mm dust-continuum emission which coincides with the MIR source and the free-free jet. Our combined H13CO+ observations have revealed a disk-like envelope. The size and the mass of the disk-like envelope are 0.15 times 0.11 pc and 5.1 - 9.1 M_sun, respectively. The combined map also shows that the outer portion of the disk-like envelope has a fan-shaped structure which delineates the rim of the CO(1-0) outflow observed with the NMA. The position-velocity (P-V) diagrams in the H13CO+ (1-0) emission show that the velocity field in the disk-like envelope is composed of a dispersing gas motion and a possible rigid-like rotation. The mass dispersing rate is estimated to be (3.4 - 6.0) times 10^-5 M_sun/yr, which implies that MMS 7 has an ability to ...

  18. Light Curves of Core-Collapse Supernovae with Substantial Mass Loss using the New Open-Source SuperNova Explosion Code (SNEC)

    CERN Document Server

    Morozova, V; Renzo, M; Ott, C D; Clausen, D; Couch, S M; Ellis, J; Roberts, L F

    2015-01-01

    We present the SuperNova Explosion Code SNEC, an open-source Lagrangian code for the hydrodynamics and equilibrium-diffusion radiation transport in the expanding envelopes of supernovae. Given a model of a progenitor star, an explosion energy, and an amount and distribution of radioactive nickel, SNEC generates the bolometric light curve, as well as the light curves in different wavelength bands assuming black body emission. As a first application of SNEC, we consider the explosions of a grid of 15 Msun (at zero-age main sequence) stars whose hydrogen envelopes are stripped to different extents and at different points in their evolution. The resulting light curves exhibit plateaus with durations of ~20-100 days if >~1.5-2 Msun of hydrogen-rich material is left and no plateau if less hydrogen-rich material is left. The shorter plateau lengths are unlike the Type IIP supernova light curves typically observed in nature. This suggests that, at least for zero-age main sequence masses <~ 20 Msun, hydrogen mass l...

  19. Embryos grown in the dead zone: Assembling the first protoplanetary cores in low mass self-gravitating circumstellar disks of gas and solids

    CERN Document Server

    Lyra, W; Klahr, H; Piskunov, N

    2008-01-01

    In the borders of the dead zones of protoplanetary disks, the inflow of gas produces a local density maximum that triggers the Rossby wave instability. The vortices that form are efficient in trapping solids. We aim to assess the possibility of gravitational collapse of the solids within the Rossby vortices. We perform global simulations of the dynamics of gas and solids in a low mass non-magnetized self-gravitating thin protoplanetary disk with the Pencil code. We use multiple particle species of radius 1, 10, 30, and 100 cm. The dead zone is modelled as a region of low viscosity. The Rossby vortices excited in the edges of the dead zone are very efficient particle traps. Within 5 orbits after their appearance, the solids achieve critical density and undergo gravitational collapse into Mars sized objects. The velocity dispersions are of the order of 10 m/s for newly formed embryos, later lowering to less than 1 m/s by drag force cooling. After 200 orbits, 38 gravitationally bound embryos were formed inside t...

  20. Retrospective analysis by data processing tools for comprehensive two-dimensional gas chromatography coupled to high resolution time-of-flight mass spectrometry: a challenge for matrix-rich sediment core sample from Tokyo Bay.

    Science.gov (United States)

    Zushi, Yasuyuki; Hashimoto, Shunji; Tamada, Masafumi; Masunaga, Shigeki; Kanai, Yutaka; Tanabe, Kiyoshi

    2014-04-18

    Data processing tools for non-target analysis using comprehensive two-dimensional gas chromatography coupled with high-resolution time-of-flight mass spectrometry (GC×GC-HRTOFMS) were developed and applied to a sediment core in Tokyo Bay, focusing on chlorinated compounds in this study. The processing tools were classified in two different methods: (1) the consecutive use of mass defect filter followed by artificial neutral loss scan (MDF/artificial NLS) as a qualitative non-target screening method and (2) Entire Domain Combined Spectra Extraction and Integration Program (ComSpec) and two-dimensional peak sentinel (T-SEN) as a semi-quantitative target screening method. MDF/artificial NLS as a non-target screening approach revealed that PCBs, followed by octachlorodibenzo dioxin (OCDD), were the main chlorinated compounds present in all sediment layers. Furthermore, unknown peaks thought to be chlorinated compounds were found in increasing numbers, some in increasing amounts. T-SEN and ComSpec as a target screening approach were adapted for automatic semi-quantitative analysis showed that, in decreasing concentration order, PCBs, OCDD, and dichlorodiphenyltrichloroethane and its metabolites (DDEs, DDDs) were the main chlorinated pollutants in the sediments. The complementary use of both techniques allows us to extract significant chlorinated pollutants, including non-targeted compounds. This retrospective analysis by this approach performed well even on matrix-rich sediment samples and provided us an interesting insight of historical trends of pollution in Tokyo Bay.

  1. L183, a Quiescent Core?

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Some observed results of NH3 (1, 1) and (2, 2) line emission in the starless dark cloud L183 are reported. Our observation suggests that the dense core of L183 has a size of ~ 0.16pc ×0.1pc with a mass of ~ 12M⊙. A velocity gradient of 4km s-1pc-1 from the north to the south was detected. The velocity shift corresponds to a central mass of ~ 5M⊙. If it is caused by rotation, the mass would be much less than the value above. This suggests that there may be more mass in the envelope of L183 than in the central region. The analysis of our data and the evidence in the literature about L183 indicate that it may be undergoing a process of collapsing to form a low-mass binary dense core.

  2. Core Java

    CERN Document Server

    Horstmann, Cay S

    2013-01-01

    Fully updated to reflect Java SE 7 language changes, Core Java™, Volume I—Fundamentals, Ninth Edition, is the definitive guide to the Java platform. Designed for serious programmers, this reliable, unbiased, no-nonsense tutorial illuminates key Java language and library features with thoroughly tested code examples. As in previous editions, all code is easy to understand, reflects modern best practices, and is specifically designed to help jumpstart your projects. Volume I quickly brings you up-to-speed on Java SE 7 core language enhancements, including the diamond operator, improved resource handling, and catching of multiple exceptions. All of the code examples have been updated to reflect these enhancements, and complete descriptions of new SE 7 features are integrated with insightful explanations of fundamental Java concepts.

  3. Modeling Core Collapse Supernovae

    Science.gov (United States)

    Mezzacappa, Anthony

    2017-01-01

    Core collapse supernovae, or the death throes of massive stars, are general relativistic, neutrino-magneto-hydrodynamic events. The core collapse supernova mechanism is still not in hand, though key components have been illuminated, and the potential for multiple mechanisms for different progenitors exists. Core collapse supernovae are the single most important source of elements in the Universe, and serve other critical roles in galactic chemical and thermal evolution, the birth of neutron stars, pulsars, and stellar mass black holes, the production of a subclass of gamma-ray bursts, and as potential cosmic laboratories for fundamental nuclear and particle physics. Given this, the so called ``supernova problem'' is one of the most important unsolved problems in astrophysics. It has been fifty years since the first numerical simulations of core collapse supernovae were performed. Progress in the past decade, and especially within the past five years, has been exponential, yet much work remains. Spherically symmetric simulations over nearly four decades laid the foundation for this progress. Two-dimensional modeling that assumes axial symmetry is maturing. And three-dimensional modeling, while in its infancy, has begun in earnest. I will present some of the recent work from the ``Oak Ridge'' group, and will discuss this work in the context of the broader work by other researchers in the field. I will then point to future requirements and challenges. Connections with other experimental, observational, and theoretical efforts will be discussed, as well.

  4. Dynamics of core accretion

    Science.gov (United States)

    Nelson, Andrew F.; Ruffert, Maximilian

    2013-02-01

    We perform three-dimensional hydrodynamic simulations of gas flowing around a planetary core of mass Mpl = 10M⊕ embedded in a near Keplerian background flow, using a modified shearing box approximation. We assume an ideal gas behaviour following an equation of state with a fixed ratio of the specific heats, γ = 1.42, consistent with the conditions of a moderate-temperature background disc with solar composition. No radiative heating or cooling is included in the models. We employ a nested grid hydrodynamic code implementing the `Piecewise Parabolic Method' with as many as six fixed nested grids, providing spatial resolution on the finest grid comparable to the present-day diameters of Neptune and Uranus. We find that a strongly dynamically active flow develops such that no static envelope can form. The activity is not sensitive to plausible variations in the rotation curve of the underlying disc. It is sensitive to the thermodynamic treatment of the gas, as modelled by prescribed equations of state (either `locally isothermal' or `locally isentropic') and the temperature of the background disc material. The activity is also sensitive to the shape and depth of the core's gravitational potential, through its mass and gravitational softening coefficient. Each of these factors influences the magnitude and character of hydrodynamic feedback of the small-scale flow on the background, and we conclude that accurate modelling of such feedback is critical to a complete understanding of the core accretion process. The varying flow pattern gives rise to large, irregular eruptions of matter from the region around the core which return matter to the background flow: mass in the envelope at one time may not be found in the envelope at any later time. No net mass accretion into the envelope is observed over the course of the simulation and none is expected, due to our neglect of cooling. Except in cases of very rapid cooling however, as defined by locally isothermal or

  5. Mercury's Protoplanetary Mass

    CERN Document Server

    Herndon, J M

    2004-01-01

    Major element fractionation among chondrites has been discussed for decades as ratios relative to Si or Mg. Recently, by expressing ratios relative to Fe, I discovered a new relationship admitting the possibility that ordinary chondrite meteorites are derived from two components, a relatively oxidized and undifferentiated, primitive component and a somewhat differentiated, planetary component, with oxidation state like the highly reduced enstatite chondrites, which I suggested was identical to Mercury's complement of lost elements. Here, on the basis of that relationship, I derive expressions, as a function of the mass of planet Mercury and the mass of its core, to estimate the mass of Mercury's lost elements, the mass of Mercury's alloy and rock protoplanetary core, and the mass of Mercury's gaseous protoplanet. Although Mercury's mass is well known, its core mass is not, being widely believed to be in the range of 70-80 percent of the planet mass. For a core mass of 75 percent, the mass of Mercury's lost el...

  6. TiO₂/SiO₂ core-shell composite-based sample preparation method for selective extraction of phospholipids from shrimp waste followed by hydrophilic interaction chromatography coupled with quadrupole time-of-flight/mass spectrometry analysis.

    Science.gov (United States)

    Shen, Qing; Cheung, Hon-Yeung

    2014-09-10

    A solid-phase extraction (SPE) procedure, using titania-coated silica (TiO2/SiO2) core-shell composites as the sorbent, combined with a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for extraction, visualization, and quantification of phospholipids in shrimp waste (Litopenaeus vannamei). The SPE protocol was optimized, and the best conditions were pH 5 of the loading solvent, 10% aqueous methanol as the washing solvent, and 1.0 mL of chloroform/methanol (1:2, v/v) as eluting solvents. Afterward, the eluate was separated on a diol hydrophilic interaction chromatography (HILIC) column. A total of 69 phospholipid species were identified and determined. The results indicated that, in comparison to previously published methods, this strategy was cost-effective and efficient in extraction, characterization, and determination of phospholipids. Meanwhile, phospholipids were abundant in shrimp waste, most of which contained unsaturated fatty acyl chains, such as 18:3 [α-linolenic acid (ALA)], 20:5 [eicosapentaenoic acid (EPA)], and 22:6 [docosahexaenoic acid (DHA)]. The successful application of this strategy paves the way for full use of traditionally discarded shrimp wastes.

  7. The sulfur depletion problem: upper limits on the H2S2, HS2, and S2 gas-phase abundances toward the low-mass warm core IRAS16293-2422

    CERN Document Server

    Martín-Doménech, R; Caro, G M Muñoz; Müller, H S P; Occhiogrosso, A; Testi, L; Woods, P M; Viti, S

    2016-01-01

    A fraction of the missing sulfur in dense clouds and circumstellar regions could be in the form of three species not yet de- tected in the interstellar medium: H2S2, HS2, and S2 according to experimental simulations performed under astrophysically relevant conditions. These S-S bonded molecules can be formed by the energetic processing of H2S-bearing ice mantles on dust grains, and subsequently desorb to the gas phase. The detection of these species could partially solve the sulfur depletion problem, and would help to improve our knowledge of the poorly known chemistry of sulfur in the interstellar medium. To this purpose we performed dedicated ground-based observations toward the low-mass warm core IRAS16293-2422. Observations in the submillimeter regime were obtained with the APEX 12 m telescope during 15 hours of observation, targeting a wide selection of the predicted rotational transitions of the three molecules. The 1{\\sigma} noise rms values were extracted in the spectral regions where the targeted spe...

  8. Core-shell polydopamine magnetic nanoparticles as sorbent in micro-dispersive solid-phase extraction for the determination of estrogenic compounds in water samples prior to high-performance liquid chromatography-mass spectrometry analysis.

    Science.gov (United States)

    Socas-Rodríguez, Bárbara; Hernández-Borges, Javier; Salazar, Pedro; Martín, Miriam; Rodríguez-Delgado, Miguel Ángel

    2015-06-05

    In this work, core-shell Fe3O4@poly(dopamine) magnetic nanoparticles (m-NPs) were prepared and characterized in our laboratory and applied as sorbents for the magnetic-micro solid phase extraction (m-μSPE) of twelve estrogenic compounds of interest (i.e. 17α-estradiol, 17β-estradiol, estrone, hexestrol, 17α-ethynylestradiol, diethylstibestrol, dienestrol, zearalenone, α-zearalanol, β-zearalanol, α-zearalenol and β-zearalenol) from different water samples. Separation, determination and quantification were achieved by high-performance liquid chromatography coupled to ion trap mass spectrometry with electrospray ionization. NPs@poly(dopamine) were synthesized by a chemical coprecipitation procedure and characterized by different surface characterization techniques (X-ray diffraction, X-ray photoelectron spectroscopy, thermogravimetric analysis, transmission and scanning electron microscopy, infrared and Raman spectroscopy, vibrating sample magnetometry, microelectrophoresis and adsorption/desorption isotherms). Parameters affecting the extraction efficiency of m-μSPE (i.e. polymerization time, pH of the sample, extraction and elution conditions) were studied and optimized. The methodology was validated for Milli-Q, mineral, tap and wastewater using 2-methoxyestradiol as internal standard, obtaining recoveries ranging from 70 to 119% with relative standard deviation values lower than 20% and limits of quantification in the range 0.02-1.1 μg/L. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Rapid and effective sample cleanup based on graphene oxide-encapsulated core-shell magnetic microspheres for determination of fifteen trace environmental phenols in seafood by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Pan, Sheng-Dong; Chen, Xiao-Hong; Shen, Hao-Yu; Li, Xiao-Ping; Cai, Mei-Qiang; Zhao, Yong-Gang; Jin, Mi-Cong

    2016-05-05

    In this study, graphene oxide-encapsulated core-shell magnetic microspheres (GOE-CS-MM) were fabricated by a self-assemble approach between positive charged poly(diallyldimethylammonium) chloride (PDDA)-modified Fe3O4@SiO2 and negative charged GO sheets via electrostatic interaction. The as-prepared GOE-CS-MM was carefully characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometer analysis (VSM), and X-ray photoelectron spectroscopy (XPS), and was used as a cleanup adsorbent in magnetic solid-phase extraction (MSPE) for determination of 15 trace-level environmental phenols in seafood coupled to liquid chromatography-tandem mass spectrometry (LC-MS/MS). The obtained results showed that the GOE-CS-MM exhibited excellent cleanup efficiency and could availably reduce the matrix effect. The cleanup mechanisms were investigated and referred to π-π stacking interaction and hydrogen bond between GOE-CS-MM and impurities in the extracts. Moreover, the extraction and cleanup conditions of GOE-CS-MM toward phenols were optimized in detail. Under the optimized conditions, the limits of detection (LODs) were found to be 0.003-0.06 μg kg(-1), and satisfactory recovery values of 84.8-103.1% were obtained for the tested seafood samples. It was confirmed that the developed method is simple, fast, sensitive, and accurate for the determination of 15 trace environmental phenols in seafood samples.

  10. Partial Safety Analysis for a Reduced Uranium Enrichment Core for the High Flux Isotope Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Primm, Trent [ORNL; Gehin, Jess C [ORNL

    2009-04-01

    A computational model of the reactor core of the High Flux Isotope Rector (HFIR) was developed in order to analyze non-destructive accidents caused by transients during reactor operation. The reactor model was built for the latest version of the nuclear analysis software package called Program for the Analysis of Reactor Transients (PARET). Analyses performed with the model constructed were compared with previous data obtained with other tools in order to benchmark the code. Finally, the model was used to analyze the behavior of the reactor under transients using a different nuclear fuel with lower enrichment of uranium (LEU) than the fuel currently used, which has a high enrichment of uranium (HEU). The study shows that the presence of fertile isotopes in LEU fuel, which increases the neutron resonance absorption, reduces the impact of transients on the fuel and enhances the negative reactivity feedback, thus, within the limitations of this study, making LEU fuel appear to be a safe alternative fuel for the reactor core.

  11. δ13C and δ18O isotopic composition of CaCO3 measured by continuous flow isotope ratio mass spectrometry: statistical evaluation and verification by application to Devils Hole core DH-11 calcite

    Science.gov (United States)

    Revesz, Kinga M.; Landwehr, Jurate M.

    2002-01-01

    A new method was developed to analyze the stable carbon and oxygen isotope ratios of small samples (400 ± 20 µg) of calcium carbonate. This new method streamlines the classical phosphoric acid/calcium carbonate (H3PO4/CaCO3) reaction method by making use of a recently available Thermoquest-Finnigan GasBench II preparation device and a Delta Plus XL continuous flow isotope ratio mass spectrometer. Conditions for which the H3PO4/CaCO3 reaction produced reproducible and accurate results with minimal error had to be determined. When the acid/carbonate reaction temperature was kept at 26 °C and the reaction time was between 24 and 54 h, the precision of the carbon and oxygen isotope ratios for pooled samples from three reference standard materials was ≤0.1 and ≤0.2 per mill or ‰, respectively, although later analysis showed that materials from one specific standard required reaction time between 34 and 54 h for δ18O to achieve this level of precision. Aliquot screening methods were shown to further minimize the total error. The accuracy and precision of the new method were analyzed and confirmed by statistical analysis. The utility of the method was verified by analyzing calcite from Devils Hole, Nevada, for which isotope-ratio values had previously been obtained by the classical method. Devils Hole core DH-11 recently had been re-cut and re-sampled, and isotope-ratio values were obtained using the new method. The results were comparable with those obtained by the classical method with correlation = +0.96 for both isotope ratios. The consistency of the isotopic results is such that an alignment offset could be identified in the re-sampled core material, and two cutting errors that occurred during re-sampling then were confirmed independently. This result indicates that the new method is a viable alternative to the classical reaction method. In particular, the new method requires less sample material permitting finer resolution and allows

  12. Core body temperature in obesity.

    Science.gov (United States)

    Heikens, Marc J; Gorbach, Alexander M; Eden, Henry S; Savastano, David M; Chen, Kong Y; Skarulis, Monica C; Yanovski, Jack A

    2011-05-01

    A lower core body temperature set point has been suggested to be a factor that could potentially predispose humans to develop obesity. We tested the hypothesis that obese individuals have lower core temperatures than those in normal-weight individuals. In study 1, nonobese [body mass index (BMI; in kg/m(2)) temperature-sensing capsules, and we measured core temperatures continuously for 24 h. In study 2, normal-weight (BMI of 18-25) and obese subjects swallowed temperature-sensing capsules to measure core temperatures continuously for ≥48 h and kept activity logs. We constructed daily, 24-h core temperature profiles for analysis. Mean (±SE) daily core body temperature did not differ significantly between the 35 nonobese and 46 obese subjects (36.92 ± 0.03°C compared with 36.89 ± 0.03°C; P = 0.44). Core temperature 24-h profiles did not differ significantly between 11 normal-weight and 19 obese subjects (P = 0.274). Women had a mean core body temperature ≈0.23°C greater than that of men (36.99 ± 0.03°C compared with 36.76 ± 0.03°C; P body temperature. It may be necessary to study individuals with function-altering mutations in core temperature-regulating genes to determine whether differences in the core body temperature set point affect the regulation of human body weight. These trials were registered at clinicaltrials.gov as NCT00428987 and NCT00266500.

  13. Limits to Determining the Core of Jupiter

    Science.gov (United States)

    Stevenson, David J.

    2016-10-01

    Simple, approximate models based on perturbations of the n=1 polytrope are used to identify some general properties of models for nearly-isentropic Jupiter-like planets where the total heavy element mass fraction is small. In these models, it is found that the radius is remarkably insensitive to the distribution of heavy elements and is effectively a measure of total heavy element enrichment (sum of core and envelope). The gravity harmonic J2 and the normalized moment of inertia α=I/MR2 are almost entirely determined by the density structure outside the core, and this depends on the reduced core mass, defined to be the actual core mass minus the mass of hydrogen and helium that would occupy that region in the absence of the core. The actual core mass or its radius or composition cannot be well determined, even when there is perfect knowledge of the equation of state, thermal state and envelope enrichment by heavy elements. The central concentration of heavy elements is approximately determined, even when the actual core is more massive and contaminated with hydrogen and helium by mixing or erosion (double diffusive convection). At fixed J2, the dependence of α on core structure is very small, and only exceeds the likely detection limit ~0.1-0.2% for very extended cores. Even though these results are obtained for a simple model, it is argued that they are semi-quantitatively applicable to realistic models. A perturbation scheme is presented for testing this systematically and for assessing the consequences of perturbations to the equation of state, compositional profile and temperature structure for the trade-off between reduced core mass and envelope enrichment.

  14. Modeling of molecular clouds with formation of prestellar cores

    CERN Document Server

    Donkov, Sava; Veltchev, Todor V

    2012-01-01

    We develop a statistical approach for description of dense structures (cores) in molecular clouds that might be progenitors of stars. Our basic assumptions are a core mass-density relationship and a power-law density distribution of these objects as testified by numerical simulations and observations. The core mass function (CMF) was derived and its slope in the high-mass regime was obtained analytically. Comparisons with observational CMFs in several Galactic clouds are briefly presented.

  15. The compactness of presupernova stellar cores

    Energy Technology Data Exchange (ETDEWEB)

    Sukhbold, Tuguldur; Woosley, S. E., E-mail: sukhbold@ucolick.org [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)

    2014-03-01

    The success or failure of the neutrino-transport mechanism for producing a supernova in an evolved massive star is known to be sensitive not only to the mass of the iron core that collapses, but also to the density gradient in the silicon and oxygen shells surrounding that core. Here we study the systematics of a presupernova core's 'compactness' as a function of the mass of the star and the physics used in its calculation. Fine-meshed surveys of presupernova evolution are calculated for stars from 15 to 65 M {sub ☉}. The metallicity and the efficiency of semiconvection and overshoot mixing are both varied and bare carbon-oxygen cores are explored as well as full hydrogenic stars. Two different codes, KEPLER and MESA, are used for the study. A complex interplay of carbon and oxygen burning, especially in shells, can cause rapid variations in the compactness for stars of very nearly the same mass. On larger scales, the distribution of compactness with main sequence mass is found to be robustly non-monotonic, implying islands of 'explodabilty,' particularly around 8-20 M {sub ☉} and 25-30 M {sub ☉}. The carbon-oxygen (CO) core mass of a presupernova star is a better, (though still ambiguous) discriminant of its core structure than the main sequence mass.

  16. Determination of lead isotopes in a new Greenland deep ice core at the sub-picogram per gram level by thermal ionization mass spectrometry using an improved decontamination method.

    Science.gov (United States)

    Han, Changhee; Burn-Nunes, Laurie J; Lee, Khanghyun; Chang, Chaewon; Kang, Jung-Ho; Han, Yeongcheol; Hur, Soon Do; Hong, Sungmin

    2015-08-01

    An improved decontamination method and ultraclean analytical procedures have been developed to minimize Pb contamination of processed glacial ice cores and to achieve reliable determination of Pb isotopes in North Greenland Eemian Ice Drilling (NEEM) deep ice core sections with concentrations at the sub-picogram per gram level. A PL-7 (Fuso Chemical) silica-gel activator has replaced the previously used colloidal silica activator produced by Merck and has been shown to provide sufficiently enhanced ion beam intensity for Pb isotope analysis for a few tens of picograms of Pb. Considering the quantities of Pb contained in the NEEM Greenland ice core and a sample weight of 10 g used for the analysis, the blank contribution from the sample treatment was observed to be negligible. The decontamination and analysis of the artificial ice cores and selected NEEM Greenland ice core sections confirmed the cleanliness and effectiveness of the overall analytical process.

  17. Dual-core antiresonant hollow core fibers.

    Science.gov (United States)

    Liu, Xuesong; Fan, Zhongwei; Shi, Zhaohui; Ma, Yunfeng; Yu, Jin; Zhang, Jing

    2016-07-25

    In this work, dual-core antiresonant hollow core fibers (AR-HCFs) are numerically demonstrated, based on our knowledge, for the first time. Two fiber structures are proposed. One is a composite of two single-core nested nodeless AR-HCFs, exhibiting low confinement loss and a circular mode profile in each core. The other has a relatively simple structure, with a whole elliptical outer jacket, presenting a uniform and wide transmission band. The modal couplings of the dual-core AR-HCFs rely on a unique mechanism that transfers power through the air. The core separation and the gap between the two cores influence the modal coupling strength. With proper designs, both of the dual-core fibers can have low phase birefringence and short modal coupling lengths of several centimeters.

  18. 13CO Cores in Taurus Molecular Cloud

    CERN Document Server

    Qian, Lei; Goldsmith, Paul

    2012-01-01

    Young stars form in molecular cores, which are dense condensations within molecular clouds. We have searched for $^{13}$CO $J=1\\to 0$ cores in the Taurus molecular cloud and studied their properties. Our data set has a spatial dynamic range (the ratio of linear map size to the pixel size) of about 1000 and spectrally resolved velocity information. We use empirical fit to the CO and CO$_2$ ice to correct the depletion. The core mass function (CMF) can be fitted better with a log-normal function than with a power law function. We also extract cores and calculate the CMF based on the integrated intensity of $^{13}$CO and the extinction from 2MASS. We demonstrate that there exists core blending, i.e. combined structures that are incoherent in velocity but continuous in column density. The resulting core samples based on 2D and 3D data thus differ significantly from each other. In particular, the cores derived from 2MASS extinction can be fitted with a power-law function, but not a log-normal function. The core ve...

  19. Animal MRI Core

    Data.gov (United States)

    Federal Laboratory Consortium — The Animal Magnetic Resonance Imaging (MRI) Core develops and optimizes MRI methods for cardiovascular imaging of mice and rats. The Core provides imaging expertise,...

  20. Massive Quiescent Cores in Orion: Dichotomy in the Dynamical Status of Cores

    Science.gov (United States)

    Velusamy, Thangasamy; Goldsmith, P. F.; Li, D.; Langer, W. D.; Pineda, J. L.; Peng, R.

    2009-01-01

    To study the evolution of high mass cores we have searched for evidence of collapse motions in a large sample of starless cores in the Orion molecular cloud. We used the Caltech Submillimeter Observatory telescope to obtain spectra of the optically thin (H13CO+) and optically thick (HCO+) high density tracer molecules in 27 cores with masses > 1 MO. The red- and blue-asymmetries seen in the line profiles of the optically thick line with respect to the optically thin line indicate that 2/3 of these cores are not static and we interpret these as evidence for inward or outward motions in 19 cores. We present RATRAN radiative transfer models of these cores that support the interpretation of inward and outward motion consistent with the observed spectral asymmetries. Thus we detect infall (inward motions) in 9 cores and outward motions for 10 cores, suggesting a dichotomy in the kinematic state in this sample. This population of massive molecular cloud cores is in general likely to be dynamic, out-of-equilibrium structures, rather than quasi-hydro/magneto-static structures. Our results provide an important observational constraint on the fraction of collapsing (inward motions) versus non-collapsing (re-expanding) cores for comparison with model simulations. This work was performed by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. Research at the Caltech Submillimeter Observatory is supported by NSF grant AST-0229008.

  1. k-core covers and the core

    NARCIS (Netherlands)

    Sanchez-Rodriguez, E.; Borm, Peter; Estevez-Fernandez, A.; Fiestras-Janeiro, G.; Mosquera, M.A.

    2015-01-01

    This paper extends the notion of individual minimal rights for a transferable utility game (TU-game) to coalitional minimal rights using minimal balanced families of a specific type, thus defining a corresponding minimal rights game. It is shown that the core of a TU-game coincides with the core of

  2. Academic Rigor: The Core of the Core

    Science.gov (United States)

    Brunner, Judy

    2013-01-01

    Some educators see the Common Core State Standards as reason for stress, most recognize the positive possibilities associated with them and are willing to make the professional commitment to implementing them so that academic rigor for all students will increase. But business leaders, parents, and the authors of the Common Core are not the only…

  3. k-core covers and the core

    NARCIS (Netherlands)

    Sanchez-Rodriguez, E.; Borm, Peter; Estevez-Fernandez, A.; Fiestras-Janeiro, G.; Mosquera, M.A.

    This paper extends the notion of individual minimal rights for a transferable utility game (TU-game) to coalitional minimal rights using minimal balanced families of a specific type, thus defining a corresponding minimal rights game. It is shown that the core of a TU-game coincides with the core of

  4. 大众传媒的价值观影响与大学生社会主义核心价值观的培育%The Influence of Mass Media on Values and Cultivation of the Socialist Core Values of the College Students

    Institute of Scientific and Technical Information of China (English)

    任艳妮

    2014-01-01

    党的十八大提出要从国家、社会、个人三个层面积极倡导和培育社会主义核心价值观。大众传媒提供了多元价值观选项并引导价值取向、左右价值判断、影响甚至代替个体做出价值选择。当代大学生面对多元化的价值选择无所适从,应采取创新大学生价值观教育模式,加强大众传媒自身建设,借助大众传媒提升社会主义核心价值观的宣传效果,培养大学生媒介素养能力等措施,积极培养大学生的社会主义核心价值观。%At the 18th CPC National Congress,it is proposed that we should promote and cultivate the socialist core values from three levels:the state, society and individual. Mass media provides us with pluralistic values,and direct our val-ue orientation,control our value judgement,influence even make the choice of value for individuals. The young people are now in the dilemma when facing the choice of pluralistic values. In this case,it is necessary to take measures such as to in-novate the model for the education of values,strengthen the self-building of mass media,promote the effect of populariza-tion of socialist core values via mass media,cultivate the students′media awareness,so as to cultivate the students′ under-standing of the socialist core values.

  5. Comodules over semiperfect corings

    CERN Document Server

    Caenepeel, S

    2011-01-01

    We discuss when the Rat functor associated to a coring satisfying the left $\\alpha$-condition is exact. We study the category of comodules over a semiperfect coring. We characterize semiperfect corings over artinian rings and over qF-rings.

  6. Coring Sample Acquisition Tool

    Science.gov (United States)

    Haddad, Nicolas E.; Murray, Saben D.; Walkemeyer, Phillip E.; Badescu, Mircea; Sherrit, Stewart; Bao, Xiaoqi; Kriechbaum, Kristopher L.; Richardson, Megan; Klein, Kerry J.

    2012-01-01

    A sample acquisition tool (SAT) has been developed that can be used autonomously to sample drill and capture rock cores. The tool is designed to accommodate core transfer using a sample tube to the IMSAH (integrated Mars sample acquisition and handling) SHEC (sample handling, encapsulation, and containerization) without ever touching the pristine core sample in the transfer process.

  7. Magnetohydrodynamic Convection in the Outer Core and its Geodynamic Consequences

    Science.gov (United States)

    Kuang, Weijia; Chao, Benjamin F.; Fang, Ming

    2004-01-01

    The Earth's fluid outer core is in vigorous convection through much of the Earth's history. In addition to generating and maintaining Earth s time-varying magnetic field (geodynamo), the core convection also generates mass redistribution in the core and a dynamical pressure field on the core-mantle boundary (CMB). All these shall result in various core-mantle interactions, and contribute to surface geodynamic observables. For example, electromagnetic core-mantle coupling arises from finite electrically conducting lower mantle; gravitational interaction occurs between the cores and the heterogeneous mantle; mechanical coupling may also occur when the CMB topography is aspherical. Besides changing the mantle rotation via the coupling torques, the mass-redistribution in the core shall produce a spatial-temporal gravity anomaly. Numerical modeling of the core dynamical processes contributes in several geophysical disciplines. It helps explain the physical causes of surface geodynamic observables via space geodetic techniques and other means, e.g. Earth's rotation variation on decadal time scales, and secular time-variable gravity. Conversely, identification of the sources of the observables can provide additional insights on the dynamics of the fluid core, leading to better constraints on the physics in the numerical modeling. In the past few years, our core dynamics modeling efforts, with respect to our MoSST model, have made significant progress in understanding individual geophysical consequences. However, integrated studies are desirable, not only because of more mature numerical core dynamics models, but also because of inter-correlation among the geophysical phenomena, e.g. mass redistribution in the outer core produces not only time-variable gravity, but also gravitational core-mantle coupling and thus the Earth's rotation variation. They are expected to further facilitate multidisciplinary studies of core dynamics and interactions of the core with other

  8. Banded transformer cores

    Science.gov (United States)

    Mclyman, C. W. T. (Inventor)

    1974-01-01

    A banded transformer core formed by positioning a pair of mated, similar core halves on a supporting pedestal. The core halves are encircled with a strap, selectively applying tension whereby a compressive force is applied to the core edge for reducing the innate air gap. A dc magnetic field is employed in supporting the core halves during initial phases of the banding operation, while an ac magnetic field subsequently is employed for detecting dimension changes occurring in the air gaps as tension is applied to the strap.

  9. Retention Models on Core-Shell Columns.

    Science.gov (United States)

    Jandera, Pavel; Hájek, Tomáš; Růžičková, Marie

    2017-07-13

    A thin, active shell layer on core-shell columns provides high efficiency in HPLC at moderately high pressures. We revisited three models of mobile phase effects on retention for core-shell columns in mixed aqueous-organic mobile phases: linear solvent strength and Snyder-Soczewiński two-parameter models and a three-parameter model. For some compounds, two-parameter models show minor deviations from linearity due to neglect of possible minor retention in pure weak solvent, which is compensated for in the three-parameter model, which does not explicitly assume either the adsorption or the partition retention mechanism in normal- or reversed-phase systems. The model retention equation can be formulated as a function of solute retention factors of nonionic compounds in pure organic solvent and in pure water (or aqueous buffer) and of the volume fraction of an either aqueous or organic solvent component in a two-component mobile phase. With core-shell columns, the impervious solid core does not participate in the retention process. Hence, the thermodynamic retention factors, defined as the ratio of the mass of the analyte mass contained in the stationary phase to its mass in the mobile phase in the column, should not include the particle core volume. The values of the thermodynamic factors are lower than the retention factors determined using a convention including the inert core in the stationary phase. However, both conventions produce correct results if consistently used to predict the effects of changing mobile phase composition on retention. We compared three types of core-shell columns with C18-, phenyl-hexyl-, and biphenyl-bonded phases. The core-shell columns with phenyl-hexyl- and biphenyl-bonded ligands provided lower errors in two-parameter model predictions for alkylbenzenes, phenolic acids, and flavonoid compounds in comparison with C18-bonded ligands.

  10. Simulation of the spherically symmetric stellar core collapse, bounce, and postbounce evolution of a star of 13 solar masses with boltzmann neutrino transport, and its implications for the supernova mechanism.

    Science.gov (United States)

    Mezzacappa, A; Liebendörfer, M; Messer, O E; Hix, W R; Thielemann, F K; Bruenn, S W

    2001-03-05

    With exact three-flavor Boltzmann neutrino transport, we simulate the stellar core collapse, bounce, and postbounce evolution of a 13M star in spherical symmetry, the Newtonian limit, without invoking convection. In the absence of convection, prior spherically symmetric models, which implemented approximations to Boltzmann transport, failed to produce explosions. We consider exact transport to determine if these failures were due to the transport approximations made and to answer remaining fundamental questions in supernova theory. The model presented here is the first in a sequence of models beginning with different progenitors. In this model, a supernova explosion is not obtained.

  11. Structure of Hot Molecular Cores

    OpenAIRE

    Rolffs, Rainer

    2011-01-01

    High-mass stars form deeply embedded in dense molecular gas, which they heat up and ionize due to their high energy output. During an early phase, the ionization is confined to small regions, and the stellar radiation is absorbed by dust. The high temperatures lead to the evaporation of ice mantles around dust grains, and many highly excited and complex molecules can be observed in these Hot Molecular Cores. At later stages, the whole molecular cloud is ionized and disrupted, and a...

  12. A condensed review of the core catcher in the LMR

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yong Bum; Hahn, Do hee

    2001-03-01

    The overwhelming emphasis in reactor safety is on the prevention of core meltdown. Moreover, although there have been several accidents that have resulted in some fuel melting, to date there have been no accidents severe enough to cause the syndrome of core collapse, reactor vessel melt-through, containment penetration, and dispersal into the ground. Nevertheless, a number of proposals have been made for the design of core catcher systems to control or stop the motion of the molten core mass should such an accident take place. Core catchers may differ in both their location within the reactor system and in the mechanism that is used to cool and control the motion of the core debris. In this report the classification, configuration and main features of the core catcher are described. And also, the core catcher provisions in constructed and planned LMRs (Liquid Metal Reactors) are summarized.

  13. A Comparison of Embedded Total Task Instruction in Teaching Behavioral Chains to Massed One-on-One Instruction for Students with Intellectual Disabilities: Accessing General Education Settings and Core Academic Content

    Science.gov (United States)

    Jameson, J. Matt; Walker, Ryan; Utley, Kristen; Maughan, Ryan

    2012-01-01

    This study is a comparison of the embedded instruction of behavioral chains with more traditional (one-on-one massed trials in special education setting) instructional procedures for teaching behavioral chains to students with significant cognitive disabilities. Although embedded instruction has emerged as a promising potential instructional…

  14. The core paradox.

    Science.gov (United States)

    Kennedy, G. C.; Higgins, G. H.

    1973-01-01

    Rebuttal of suggestions from various critics attempting to provide an escape from the seeming paradox originated by Higgins and Kennedy's (1971) proposed possibility that the liquid in the outer core was thermally stably stratified and that this stratification might prove a powerful inhibitor to circulation of the outer core fluid of the kind postulated for the generation of the earth's magnetic field. These suggestions are examined and shown to provide no reasonable escape from the core paradox.

  15. K-core inflation

    OpenAIRE

    Alexander L. Wolman

    2011-01-01

    K-core inflation is a new class of underlying inflation measures. The two most popular measures of underlying inflation are core inflation and trimmed mean inflation. The former removes fixed categories of goods and services (food and energy) from the inflation calculation, and the latter removes fixed percentiles of the weighted distribution of price changes. In contrast, k-core inflation specifies a size of relative price change to be removed from the inflation calculation. Thus, the catego...

  16. Sediment Core Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Provides instrumentation and expertise for physical and geoacoustic characterization of marine sediments. DESCRIPTION: The multisensor core logger measures...

  17. Sediment Core Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Provides instrumentation and expertise for physical and geoacoustic characterization of marine sediments.DESCRIPTION: The multisensor core logger measures...

  18. Core body temperature in obesity123

    Science.gov (United States)

    Heikens, Marc J; Gorbach, Alexander M; Eden, Henry S; Savastano, David M; Chen, Kong Y; Skarulis, Monica C

    2011-01-01

    Background: A lower core body temperature set point has been suggested to be a factor that could potentially predispose humans to develop obesity. Objective: We tested the hypothesis that obese individuals have lower core temperatures than those in normal-weight individuals. Design: In study 1, nonobese [body mass index (BMI; in kg/m2) temperature–sensing capsules, and we measured core temperatures continuously for 24 h. In study 2, normal-weight (BMI of 18–25) and obese subjects swallowed temperature-sensing capsules to measure core temperatures continuously for ≥48 h and kept activity logs. We constructed daily, 24-h core temperature profiles for analysis. Results: Mean (±SE) daily core body temperature did not differ significantly between the 35 nonobese and 46 obese subjects (36.92 ± 0.03°C compared with 36.89 ± 0.03°C; P = 0.44). Core temperature 24-h profiles did not differ significantly between 11 normal-weight and 19 obese subjects (P = 0.274). Women had a mean core body temperature ≈0.23°C greater than that of men (36.99 ± 0.03°C compared with 36.76 ± 0.03°C; P body temperature. It may be necessary to study individuals with function-altering mutations in core temperature–regulating genes to determine whether differences in the core body temperature set point affect the regulation of human body weight. These trials were registered at clinicaltrials.gov as NCT00428987 and NCT00266500. PMID:21367952

  19. Helium in Earth's early core

    Science.gov (United States)

    Bouhifd, M. A.; Jephcoat, Andrew P.; Heber, Veronika S.; Kelley, Simon P.

    2013-11-01

    The observed escape of the primordial helium isotope, 3He, from the Earth's interior indicates that primordial helium survived the energetic process of planetary accretion and has been trapped within the Earth to the present day. Two distinct reservoirs in the Earth's interior have been invoked to account for variations in the 3He/4He ratio observed at the surface in ocean basalts: a conventional depleted mantle source and a deep, still enigmatic, source that must have been isolated from processing throughout Earth history. The Earth's iron-based core has not been considered a potential helium source because partitioning of helium into metal liquid has been assumed to be negligible. Here we determine helium partitioning in experiments between molten silicates and iron-rich metal liquids at conditions up to 16GPa and 3,000K. Analyses of the samples by ultraviolet laser ablation mass spectrometry yield metal-silicate helium partition coefficients that range between 4.7×10-3 and 1.7×10-2 and suggest that significant quantities of helium may reside in the core. Based on estimated concentrations of primordial helium, we conclude that the early core could have incorporated enough helium to supply deep-rooted plumes enriched in 3He throughout the age of the Earth.

  20. Rest mass or inertial mass?

    OpenAIRE

    Khrapko, R. I.

    2001-01-01

    Rest mass takes the place of inertial mass in modern physics textbooks. It seems to be wrong. But this phenomenon is hidden away by the facts that rest mass adherents busily call rest mass "mass", not rest mass, and the word "mass" is associated with a measure of inertia. This topic has been considered by the author in the article "What is mass?" [1, 2, 3]. Additional arguments to a confirmation of such a thesis are presented here.

  1. Isolated starless cores in IRDCs in the Hi-GAL survey

    CERN Document Server

    Wilcock, L A; Kirk, J M; Stamatellos, D; Whitworth, A; Battersby, C; Elia, D; Fuller, G A; DiGiorgio, A; Griffin, M J; Molinari, S; Martin, P; Mottram, J C; Peretto, N; Pestalozzi, M; Schisano, E; Smith, H A; Thompson, M A

    2012-01-01

    In a previous paper we identified cores within infrared dark clouds (IRDCs). We regarded those without embedded sources as the least evolved, and labelled them starless. Here we identify the most isolated starless cores and model them using a three-dimensional, multi-wavelength, Monte Carlo, radiative transfer code. We derive the cores' physical parameters and discuss the relation between the mass, temperature, density, size and the surrounding interstellar radiation field (ISRF) for the cores. The masses of the cores were found not to correlate with their radial size or central density. The temperature at the surface of a core was seen to depend almost entirely on the level of the ISRF surrounding the core. No correlation was found between the temperature at the centre of a core and its local ISRF. This was seen to depend, instead, on the density and mass of the core.

  2. Millimeter continuum observations of Galactic center giant molecular cloud cores

    Science.gov (United States)

    Lis, D. C.; Carlstrom, J. E.; Keene, Jocelyn

    1991-01-01

    Results are presented of observations of 1.3- and 0.8-mm continuum emission toward the cores of three Galactic center molecular clouds with ongoing massive star formation, Sagittarius B2, C, and D, which were made in order to study possible variations in the high-mass star formation rate per unit mass between the Galactic center and the disk. The luminosity-to-mass ratio, based on the mass estimates derived from the millimeter continuum emission, is used as a tracer of the high-mass star formation rate in GMC cores. The magnitude of errors involved in using millimeter continuum emission for determining the core mass is estimated through radiative transfer modeling. It is inferred from the present millimeter data, along with previously published far-infrared data, that the Sgr C and D cores are very similar in terms of mean dust optical depth and temperature. The luminosity-to-mass ratios derived for the Sgr C and D cores are found to be consistent with those of typical disk GMC cores with comparable far-infrared luminosities.

  3. Research on plasma core reactors

    Energy Technology Data Exchange (ETDEWEB)

    Jarvis, G.A.; Barton, D.M.; Helmick, H.H.; Bernard, W.; White, R.H.

    1977-01-01

    Experiments and theoretical studies are being conducted for NASA on critical assemblies with 1-m-diam by 1-m-long low-density cores surrounded by a thick beryllium reflector. These assemblies make extensive use of existing nuclear propulsion reactor components, facilities, and instrumentation. Due to excessive porosity in the reflector, the initial critical mass was 19 kg U(93.2). Addition of a 17-cm-thick by 89-cm-diam beryllium flux trap in the cavity reduced the critical mass to 7 kg when all the uranium was in the zone just outside the flux trap. A mockup aluminum UF/sub 6/ container was placed inside the flux trap and fueled with uranium-graphite elements. Fission distributions and reactivity worths of fuel and structural materials were measured. Finally, an 85,000-cm/sup 3/ aluminum canister in the central region was fueled with UF/sub 6/ gas and fission density distributions determined. These results will be used to guide the design of a prototype plasma core reactor which will test energy removal by optical radiation.

  4. A Hunt for Massive Starless Cores

    CERN Document Server

    Kong, Shuo; Caselli, Paola; Fontani, Francesco; Liu, Mengyao; Butler, Michael J

    2016-01-01

    We carry out an ALMA $\\rm N_2D^+$(3-2) and 1.3~mm continuum survey towards 32 high mass surface density regions in seven Infrared Dark Clouds with the aim of finding massive starless cores, which may be the initial conditions for the formation of massive stars. Cores showing strong $\\rm N_2D^+$(3-2) emission are expected to be highly deuterated and indicative of early, potentially pre-stellar stages of star formation. We also present maps of these regions in ancillary line tracers, including C$^{18}$O(2-1), DCN(3-2) and DCO$^+$(3-2). Over 100 $\\rm N_2D^+$ cores are identified with our newly developed core-finding algorithm based on connected structures in position-velocity space. The most massive core has $\\gtrsim70\\:M_\\odot$ (potentially $\\sim170\\:M_\\odot$) and so may be representative of the initial conditions for massive star formation. The existence and dynamical properties of such cores constrain massive star formation theories. We measure the line widths and thus velocity dispersion of six of the cores ...

  5. Ice Core Investigations

    Science.gov (United States)

    Krim, Jessica; Brody, Michael

    2008-01-01

    What can glaciers tell us about volcanoes and atmospheric conditions? How does this information relate to our understanding of climate change? Ice Core Investigations is an original and innovative activity that explores these types of questions. It brings together popular science issues such as research, climate change, ice core drilling, and air…

  6. Making an Ice Core.

    Science.gov (United States)

    Kopaska-Merkel, David C.

    1995-01-01

    Explains an activity in which students construct a simulated ice core. Materials required include only a freezer, food coloring, a bottle, and water. This hands-on exercise demonstrates how a glacier is formed, how ice cores are studied, and the nature of precision and accuracy in measurement. Suitable for grades three through eight. (Author/PVD)

  7. Ice Core Investigations

    Science.gov (United States)

    Krim, Jessica; Brody, Michael

    2008-01-01

    What can glaciers tell us about volcanoes and atmospheric conditions? How does this information relate to our understanding of climate change? Ice Core Investigations is an original and innovative activity that explores these types of questions. It brings together popular science issues such as research, climate change, ice core drilling, and air…

  8. Iowa Core Annual Report

    Science.gov (United States)

    Iowa Department of Education, 2015

    2015-01-01

    One central component of a great school system is a clear set of expectations, or standards, that educators help all students reach. In Iowa, that effort is known as the Iowa Core. The Iowa Core represents the statewide academic standards, which describe what students should know and be able to do in math, science, English language arts, and…

  9. Mercury's core evolution

    Science.gov (United States)

    Deproost, Marie-Hélène; Rivoldini, Attilio; Van Hoolst, Tim

    2016-10-01

    Remote sensing data of Mercury's surface by MESSENGER indicate that Mercury formed under reducing conditions. As a consequence, silicon is likely the main light element in the core together with a possible small fraction of sulfur. Compared to sulfur, which does almost not partition into solid iron at Mercury's core conditions and strongly decreases the melting temperature, silicon partitions almost equally well between solid and liquid iron and is not very effective at reducing the melting temperature of iron. Silicon as the major light element constituent instead of sulfur therefore implies a significantly higher core liquidus temperature and a decrease in the vigor of compositional convection generated by the release of light elements upon inner core formation.Due to the immiscibility in liquid Fe-Si-S at low pressure (below 15 GPa), the core might also not be homogeneous and consist of an inner S-poor Fe-Si core below a thinner Si-poor Fe-S layer. Here, we study the consequences of a silicon-rich core and the effect of the blanketing Fe-S layer on the thermal evolution of Mercury's core and on the generation of a magnetic field.

  10. Mars' core and magnetism.

    Science.gov (United States)

    Stevenson, D J

    2001-07-12

    The detection of strongly magnetized ancient crust on Mars is one of the most surprising outcomes of recent Mars exploration, and provides important insight about the history and nature of the martian core. The iron-rich core probably formed during the hot accretion of Mars approximately 4.5 billion years ago and subsequently cooled at a rate dictated by the overlying mantle. A core dynamo operated much like Earth's current dynamo, but was probably limited in duration to several hundred million years. The early demise of the dynamo could have arisen through a change in the cooling rate of the mantle, or even a switch in convective style that led to mantle heating. Presently, Mars probably has a liquid, conductive outer core and might have a solid inner core like Earth.

  11. Multiplicity and disks within the high-mass core NGC 7538IRS1. Resolving cm line and continuum emission at 0.06″ × 0.05″ resolution

    Science.gov (United States)

    Beuther, H.; Linz, H.; Henning, Th.; Feng, S.; Teague, R.

    2017-09-01

    Context. High-mass stars have a high degree of multiplicity and most likely form via disk accretion processes. The detailed physics of the binary and disk formation are still poorly constrained. Aims: We seek to resolve the central substructures of the prototypical high-mass star-forming region NGC 7538IRS1 at the highest possible spatial resolution in line and continuum emission to investigate the protostellar environment and kinematics. Methods: Using the Karl G. Jansky Very Large Array (VLA) in its most extended configuration at 24 GHz has allowed us to study the NH3 and thermal CH3OH emission and absorption as well as the cm continuum emission at an unprecedented spatial resolution of 0.06″ × 0.05″, corresponding to a linear resolution of 150 AU at a distance of 2.7 kpc. Results: A comparison of these new cm continuum data with previous VLA observations from 23 yr ago reveals no recognizable proper motions. If the emission were caused by a protostellar jet, proper motion signatures should have been easily identified. In combination with the high spectral indices S ∝ να (α between 1 and 2), this allows us to conclude that the continuum emission is from two hypercompact Hii regions separated in projection by about 430 AU. The NH3 spectral line data reveal a common rotating envelope indicating a bound high-mass binary system. In addition to this, the thermal CH3OH data show two separate velocity gradients across the two hypercompact Hii regions. This indicates two disk-like structures within the same rotating circumbinary envelope. Disk and envelope structures are inclined by 33 °, which can be explained by initially varying angular momentum distributions within the natal, turbulent cloud. Conclusions: Studying high-mass star formation at sub-0.1″ resolution allows us to isolate multiple sources as well as to separate circumbinary from disk-like rotating structures. These data show also the limitations in molecular line studies in investigating the

  12. The t-core of an s-core

    OpenAIRE

    Fayers, Matthew

    2010-01-01

    We consider the $t$-core of an $s$-core partition, when $s$ and $t$ are coprime positive integers. Olsson has shown that the $t$-core of an $s$-core is again an $s$-core, and we examine certain actions of the affine symmetric group on $s$-cores which preserve the $t$-core of an $s$-core. Along the way, we give a new proof of Olsson's result. We also give a new proof of a result of Vandehey, showing that there is a simultaneous $s$- and $t$-core which contains all others.

  13. The t-core of an s-core

    OpenAIRE

    Fayers, Matthew

    2010-01-01

    We consider the $t$-core of an $s$-core partition, when $s$ and $t$ are coprime positive integers. Olsson has shown that the $t$-core of an $s$-core is again an $s$-core, and we examine certain actions of the affine symmetric group on $s$-cores which preserve the $t$-core of an $s$-core. Along the way, we give a new proof of Olsson's result. We also give a new proof of a result of Vandehey, showing that there is a simultaneous $s$- and $t$-core which contains all others.

  14. Evaluation of Treatments to Reduce Hardness of Agave americana Core

    OpenAIRE

    Ramírez, José A.; Gómez-Ayala, Rocio C.; Cuauhtémoc Jacques-Hernández; Manuel Vázquez

    2006-01-01

    Agave americana contains inulin as storage carbohydrate. Therefore, agave is interesting to be used for the extraction of inulin by pressing. The yield of the process is low due to the high hardness of the core. The objective of this work was to evaluate pretreatments to reduce the hardness in the process of obtaining inulin by pressing. Treatments with water, sulphuric acid 1 % (by mass) or sodium hydroxide 1 % (by mass) were tested and optimized. The pretreatment of the core of A. americana...

  15. Korrelasjon mellom core styrke, core stabilitet og utholdende styrke i core

    OpenAIRE

    Berg-Olsen, Andrea Marie; Fugelsøy, Eivor; Maurstad, Ann-Louise

    2010-01-01

    Formålet med studien var å se hvilke korrelasjon det er mellom core styrke, core stabilitet og utholdende styrke i core. Testingen bestod av tre hoveddeler hvor vi testet core styrke, core stabilitet og utholdende styrke i core. Innenfor core styrke og utholdende styrke i core ble tre ulike tester utført. Ved måling av core stabilitet ble det gjennomført kun en test. I core styrke ble isometrisk abdominal fleksjon, isometrisk rygg ekstensjon og isometrisk lateral fleksjon testet. Sit-ups p...

  16. Korrelasjon mellom core styrke, core stabilitet og utholdende styrke i core

    OpenAIRE

    Berg-Olsen, Andrea Marie; Fugelsøy, Eivor; Maurstad, Ann-Louise

    2010-01-01

    Formålet med studien var å se hvilke korrelasjon det er mellom core styrke, core stabilitet og utholdende styrke i core. Testingen bestod av tre hoveddeler hvor vi testet core styrke, core stabilitet og utholdende styrke i core. Innenfor core styrke og utholdende styrke i core ble tre ulike tester utført. Ved måling av core stabilitet ble det gjennomført kun en test. I core styrke ble isometrisk abdominal fleksjon, isometrisk rygg ekstensjon og isometrisk lateral fleksjon testet. Sit-ups p...

  17. Earth's inner core: Innermost inner core or hemispherical variations?

    NARCIS (Netherlands)

    Lythgoe, K. H.; Deuss, A.; Rudge, J. F.; Neufeld, J. A.

    2014-01-01

    The structure of Earth's deep inner core has important implications for core evolution, since it is thought to be related to the early stages of core formation. Previous studies have suggested that there exists an innermost inner core with distinct anisotropy relative to the rest of the inner core.

  18. Earth's inner core: Innermost inner core or hemispherical variations?

    NARCIS (Netherlands)

    Lythgoe, K. H.; Deuss, A.; Rudge, J. F.; Neufeld, J. A.

    2014-01-01

    The structure of Earth's deep inner core has important implications for core evolution, since it is thought to be related to the early stages of core formation. Previous studies have suggested that there exists an innermost inner core with distinct anisotropy relative to the rest of the inner core.

  19. Photoevaporating transitional discs and molecular cloud cores

    Science.gov (United States)

    Li, Min; Sui, Ning

    2017-04-01

    We investigate the evolution of photoevaporating protoplanetary discs including mass influx from molecular cloud cores. We examine the influence of cloud core properties on the formation and evolution of transitional discs. We use one-dimensional thin disc assumption and calculate the evolution of the protoplanetary disc. The effects of X-ray photoevaporation are also included. Our calculations suggest that most discs should experience the transitional disc phase within 10 Myr. The formation time of a gap and its initial location are functions of the properties of the cloud cores. In some circumstances, discs can open two gaps by photoevaporation alone. The two gaps form when the gas in the disc can expand to large radius and if the mass at large radius is sufficiently small. The surface density profile of the disc determines whether the two gaps can form. Since the structure of a disc is determined by the properties of a molecular cloud core, the core properties determine the formation of two gaps in the disc. We further find that even when the photoevaporation rate is reduced to 10 per cent of the standard value, two gaps can still form in the disc. The only difference is that the formation time is delayed.

  20. Stellar core collapse. I - Infall epoch

    Science.gov (United States)

    van Riper, K. A.; Lattimer, J. M.

    1981-10-01

    Simulations of the collapse of the central iron core of a 15-solar-mass spherically symmetric star are reported. In this paper the infall epoch, between the onset of collapse and core bounce, is considered. The models use the recent equation of state of Lamb, Lattimer, Pethick, and Ravenhall and general-relativistic hydrodynamics. The electron capture rates on nuclei proceed rapidly for densities less than 10 to the 11th g/cu cm, but are suppressed at higher densities where the neutron number of the nucleus, N, exceeds 40 (Fuller, Fowler, and Newman). Neutrino transport is treated by a leakage scheme. The effects of changes in the neutrino trapping density and of qualitative changes in the electron capture reactions on the evolution are explored. Greater lepton loss during collapse leads to larger pressure deficits, more rapid collapse, and smaller inner homologous cores. The entropy change during the infall is small, the absolute value of delta s being less than 0.8. The mass of inner core is given, to about 20%, by the formula of Goldreich and Weber. Because the collapsing core is far from equilibrium, the effects of general relativity are small.

  1. Dark matter cores all the way down

    Science.gov (United States)

    Read, J. I.; Agertz, O.; Collins, M. L. M.

    2016-07-01

    We use high-resolution simulations of isolated dwarf galaxies to study the physics of dark matter cusp-core transformations at the edge of galaxy formation: M200 = 107-109 M⊙. We work at a resolution (˜4 pc minimum cell size; ˜250 M⊙ per particle) at which the impact from individual supernovae explosions can be resolved, becoming insensitive to even large changes in our numerical `sub-grid' parameters. We find that our dwarf galaxies give a remarkable match to the stellar light profile; star formation history; metallicity distribution function; and star/gas kinematics of isolated dwarf irregular galaxies. Our key result is that dark matter cores of size comparable to the stellar half-mass radius r1/2 always form if star formation proceeds for long enough. Cores fully form in less than 4 Gyr for the M200 = 108 M⊙ and ˜14 Gyr for the 109 M⊙ dwarf. We provide a convenient two parameter `CORENFW' fitting function that captures this dark matter core growth as a function of star formation time and the projected stellar half-mass radius. Our results have several implications: (i) we make a strong prediction that if Λcold dark matter is correct, then `pristine' dark matter cusps will be found either in systems that have truncated star formation and/or at radii r > r1/2; (ii) complete core formation lowers the projected velocity dispersion at r1/2 by a factor of ˜2, which is sufficient to fully explain the `too-big-to-fail problem'; and (iii) cored dwarfs will be much more susceptible to tides, leading to a dramatic scouring of the sub-halo mass function inside galaxies and groups.

  2. IGCSE core mathematics

    CERN Document Server

    Wall, Terry

    2013-01-01

    Give your core level students the support and framework they require to get their best grades with this book dedicated to the core level content of the revised syllabus and written specifically to ensure a more appropriate pace. This title has been written for Core content of the revised Cambridge IGCSE Mathematics (0580) syllabus for first teaching from 2013. ? Gives students the practice they require to deepen their understanding through plenty of practice questions. ? Consolidates learning with unique digital resources on the CD, included free with every book. We are working with Cambridge

  3. Core shroud corner joints

    Science.gov (United States)

    Gilmore, Charles B.; Forsyth, David R.

    2013-09-10

    A core shroud is provided, which includes a number of planar members, a number of unitary corners, and a number of subassemblies each comprising a combination of the planar members and the unitary corners. Each unitary corner comprises a unitary extrusion including a first planar portion and a second planar portion disposed perpendicularly with respect to the first planar portion. At least one of the subassemblies comprises a plurality of the unitary corners disposed side-by-side in an alternating opposing relationship. A plurality of the subassemblies can be combined to form a quarter perimeter segment of the core shroud. Four quarter perimeter segments join together to form the core shroud.

  4. Determination of free cortisol and free cortisone in human urine by on-line turbulent flow chromatography coupled to fused-core chromatography-tandem mass spectrometry (TFC-HPLC-MS/MS).

    Science.gov (United States)

    Sánchez-Guijo, Alberto; Hartmann, Michaela F; Shi, Lijie; Remer, Thomas; Wudy, Stefan A

    2014-01-01

    Urinary free cortisol and urinary free cortisone are decisive markers for the diagnosis of syndromes related to the dysfunction of the adrenal gland or to evaluate certain enzymatic disorders. Here, we present a new method, designed for routine laboratory use, which enables quick determination of these analytes with minor sample workup. Turbulent flow chromatography shortens sample preparation, and connection to a fused-core particle-packed column (rugged amide-embedded C18 phase) permits a rapid and effective separation of the analytes, as well as additional separation from other related and isobaric compounds present in urine. Urinary isobaric compounds were successfully identified. The method requires only 100 μl of urine supernatant per sample. The total time between injections is 9.5 min. The solvents used for both turbulent and analytical chromatography are water and methanol, and the relatively low flows needed during the method resulted in an extended life of the columns. Linearity showed a R (2) > 0.994. Limit of detection and limit of quantification are 0.5 and 1.0 ng/ml for cortisone and 1.0 and 2.0 ng/ml for cortisol. Recoveries ranged from 99.7 to 109.1 % for cortisone and from 98.7 to 102.9 % for cortisol. Accuracy values (relative errors) for intra- and inter-assay experiments were always below 8 %, whereas precision (percent CV) ranged from 3.7 to 10.7 %. No matrix effects were detected during the validation process. The reproducibility for each analyte's retention time was excellent, with a coefficient of variation always below 0.2 %. The final validation step included the study of urine samples from healthy children and from children previously diagnosed with corticoidal disorders. The high selectivity achieved enables quick data handling.

  5. Core-Collapse supernovae and its progenitors

    CERN Document Server

    Bose, Subhash; Misra, Kuntal

    2016-01-01

    Massive stars unable to sustain gravitational collapse, at the end of nuclear burning stage, turns out into core-collapse supernovae, leaving behind compact objects like neutron stars or black holes. The progenitor properties like mass and metallicity primarily governs the explosion parameters and type of compact remnant. In this contribution we summarize observational study of three Core Collapse type IIP SNe 2012aw, 2013ab and 2013ej, which are rigorously observed from ARIES and other Indian observatories and discuss their progenitor and explosion properties.

  6. Biospecimen Core Resource - TCGA

    Science.gov (United States)

    The Cancer Genome Atlas (TCGA) Biospecimen Core Resource centralized laboratory reviews and processes blood and tissue samples and their associated data using optimized standard operating procedures for the entire TCGA Research Network.

  7. NICHD Zebrafish Core

    Data.gov (United States)

    Federal Laboratory Consortium — The core[HTML_REMOVED]s goal is to help researchers of any expertise perform zebrafish experiments aimed at illuminating basic biology and human disease mechanisms,...

  8. iPSC Core

    Data.gov (United States)

    Federal Laboratory Consortium — The induced Pluripotent Stem Cells (iPSC) Core was created in 2011 to accelerate stem cell research in the NHLBI by providing investigators consultation, technical...

  9. Reference: -300CORE [PLACE

    Lifescience Database Archive (English)

    Full Text Available -300CORE Forde BG, Heyworth A, Pywell J, Kreis M Nucleotide sequence of a B1 hordein gene and the identifica...tion of possible upstream regulatory elements in endosperm storage protein genes fr

  10. INTEGRAL core programme

    Science.gov (United States)

    Gehrels, N.; Schoenfelder, V.; Ubertini, P.; Winkler, C.

    1997-01-01

    The International Gamma Ray Astrophysics Laboratory (INTEGRAL) mission is described with emphasis on the INTEGRAL core program. The progress made in the planning activities for the core program is reported on. The INTEGRAL mission has a nominal lifetime of two years with a five year extension option. The observing time will be divided between the core program (between 30 and 35 percent during the first two years) and general observations. The core program consists of three main elements: the deep survey of the Galactic plane in the central radian of the Galaxy; frequent scans of the Galactic plane in the search for transient sources, and pointed observations of several selected sources. The allocation of the observation time is detailed and the sensitivities of the observations are outlined.

  11. Focusing on Core Business

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    China is regulating state-owned enterprises that are investing outside of their core business realms, concerned that poor investment decisions could lead to loss of state-owned assets, but some doubt the effect of the new regulation

  12. Organizing Core Tasks

    DEFF Research Database (Denmark)

    Boll, Karen

    Civil servants conduct the work which makes welfare states functions on an everyday bases: Police men police, school teachers teach, and tax inspectors inspect. Focus in this paper is on the core tasks of tax inspectors. The paper argues that their core task of securing the collection of revenue...... has remained much the same within the last 10 years. However, how the core task has been organized has changed considerable under the influence of various “organizing devices”. The paper focusses on how organizing devices such as risk assessment, output-focus, effect orientation, and treatment...... projects influence the organization of core tasks within the tax administration. The paper shows that the organizational transformations based on the use of these devices have had consequences both for the overall collection of revenue and for the employees’ feeling of “making a difference”. All in all...

  13. CORE SHAPES AND ORIENTATIONS OF CORE-SÉRSIC GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Dullo, Bililign T.; Graham, Alister W., E-mail: Bdullo@astro.swin.edu.au [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, Victoria 3122 (Australia)

    2015-01-01

    The inner and outer shapes and orientations of core-Sérsic galaxies may hold important clues to their formation and evolution. We have therefore measured the central and outer ellipticities and position angles for a sample of 24 core-Sérsic galaxies using archival Hubble Space Telescope (HST) images and data. By selecting galaxies with core-Sérsic break radii R{sub b} —a measure of the size of their partially depleted core—that are ≳ 0.''2, we find that the ellipticities and position angles are quite robust against HST seeing. For the bulk of the galaxies, there is a good agreement between the ellipticities and position angles at the break radii and the average outer ellipticities and position angles determined over R {sub e}/2 < R < R {sub e}, where R {sub e} is the spheroids' effective half light radius. However there are some interesting differences. We find a median ''inner'' ellipticity at R{sub b} of ε{sub med} = 0.13 ± 0.01, rounder than the median ellipticity of the ''outer'' regions ε{sub med} = 0.20 ± 0.01, which is thought to reflect the influence of the central supermassive black hole at small radii. In addition, for the first time we find a trend, albeit weak (2σ significance), such that galaxies with larger (stellar deficit-to-supermassive black hole) mass ratios—thought to be a measure of the number of major dry merger events—tend to have rounder inner and outer isophotes, suggesting a connection between the galaxy shapes and their merger histories. We show that this finding is not simply reflecting the well known result that more luminous galaxies are rounder, but it is no doubt related.

  14. Simulations of solitonic core mergers in ultra-light axion dark matter cosmologies

    CERN Document Server

    Schwabe, Bodo; Engels, Jan F

    2016-01-01

    Using three-dimensional simulations, we study the dynamics and final structure of merging solitonic cores predicted to form in ultra-light axion dark matter halos. The classical, Newtonian equations of motion of a self-gravitating scalar field are described by the Schr\\"odinger-Poisson equations. We investigate mergers of ground state (boson star) configurations with varying mass ratios, relative phases, orbital angular momenta and initial separation with the primary goal to understand the mass loss of the emerging core by gravitational cooling. Previous results showing that the final density profiles have solitonic cores and NFW-like tails are confirmed. In binary mergers, the final core mass does not depend on initial phase difference or angular momentum and only depends on mass ratio, total initial mass, and total energy of the system. For non-zero angular momenta, the otherwise spherical cores become rotating ellipsoids. The results for mergers of multiple cores are qualitatively identical.

  15. Simulations of solitonic core mergers in ultralight axion dark matter cosmologies

    Science.gov (United States)

    Schwabe, Bodo; Niemeyer, Jens C.; Engels, Jan F.

    2016-08-01

    Using three-dimensional simulations, we study the dynamics and final structure of merging solitonic cores predicted to form in ultralight axion dark matter halos. The classical, Newtonian equations of motion of a self-gravitating scalar field are described by the Schrödinger-Poisson equations. We investigate mergers of ground state (boson star) configurations with varying mass ratios, relative phases, orbital angular momenta and initial separation with the primary goal to understand the mass loss of the emerging core by gravitational cooling. Previous results showing that the final density profiles have solitonic cores and Navarro-Frenk-White-like tails are confirmed. In binary mergers, the final core mass does not depend on initial phase difference or angular momentum and only depends on mass ratio, total initial mass, and total energy of the system. For nonzero angular momenta, the otherwise spherical cores become rotating ellipsoids. The results for mergers of multiple cores are qualitatively identical.

  16. Axino mass

    CERN Document Server

    Kim, Jihn E

    2012-01-01

    I will talk on my recent works. Axino, related to the SUSY transformation of axion, can mix with Goldstino in principle. In this short talk, I would like to explain what is the axino mass and its plausible mass range. The axino mass is known to have a hierarchical mass structure depending on accidental symmetries. With only one axino, if G_A=0 where G=K+ 2ln|W|, we obtain axino mass= gravitino mass. For G_A nonzero, the axino mass depends on the details of the Kaehler potential. I also comment on the usefulness of a new parametrization of the CKM matrix.

  17. Core-shell microparticles for protein sequestration and controlled release of a protein-laden core.

    Science.gov (United States)

    Rinker, Torri E; Philbrick, Brandon D; Temenoff, Johnna S

    2016-12-21

    Development of multifunctional biomaterials that sequester, isolate, and redeliver cell-secreted proteins at a specific timepoint may be required to achieve the level of temporal control needed to more fully regulate tissue regeneration and repair. In response, we fabricated core-shell heparin-poly(ethylene-glycol) (PEG) microparticles (MPs) with a degradable PEG-based shell that can temporally control delivery of protein-laden heparin MPs. Core-shell MPs were fabricated via a re-emulsification technique and the number of heparin MPs per PEG-based shell could be tuned by varying the mass of heparin MPs in the precursor PEG phase. When heparin MPs were loaded with bone morphogenetic protein-2 (BMP-2) and then encapsulated into core-shell MPs, degradable core-shell MPs initiated similar C2C12 cell alkaline phosphatase (ALP) activity as the soluble control, while non-degradable core-shell MPs initiated a significantly lower response (85+19% vs. 9.0+4.8% of the soluble control, respectively). Similarly, when degradable core-shell MPs were formed and then loaded with BMP-2, they induced a ∼7-fold higher C2C12 ALP activity than the soluble control. As C2C12 ALP activity was enhanced by BMP-2, these studies indicated that degradable core-shell MPs were able to deliver a bioactive, BMP-2-laden heparin MP core. Overall, these dynamic core-shell MPs have the potential to sequester, isolate, and then redeliver proteins attached to a heparin core to initiate a cell response, which could be of great benefit to tissue regeneration applications requiring tight temporal control over protein presentation.

  18. Packing in protein cores

    Science.gov (United States)

    Gaines, J. C.; Clark, A. H.; Regan, L.; O'Hern, C. S.

    2017-07-01

    Proteins are biological polymers that underlie all cellular functions. The first high-resolution protein structures were determined by x-ray crystallography in the 1960s. Since then, there has been continued interest in understanding and predicting protein structure and stability. It is well-established that a large contribution to protein stability originates from the sequestration from solvent of hydrophobic residues in the protein core. How are such hydrophobic residues arranged in the core; how can one best model the packing of these residues, and are residues loosely packed with multiple allowed side chain conformations or densely packed with a single allowed side chain conformation? Here we show that to properly model the packing of residues in protein cores it is essential that amino acids are represented by appropriately calibrated atom sizes, and that hydrogen atoms are explicitly included. We show that protein cores possess a packing fraction of φ ≈ 0.56 , which is significantly less than the typically quoted value of 0.74 obtained using the extended atom representation. We also compare the results for the packing of amino acids in protein cores to results obtained for jammed packings from discrete element simulations of spheres, elongated particles, and composite particles with bumpy surfaces. We show that amino acids in protein cores pack as densely as disordered jammed packings of particles with similar values for the aspect ratio and bumpiness as found for amino acids. Knowing the structural properties of protein cores is of both fundamental and practical importance. Practically, it enables the assessment of changes in the structure and stability of proteins arising from amino acid mutations (such as those identified as a result of the massive human genome sequencing efforts) and the design of new folded, stable proteins and protein-protein interactions with tunable specificity and affinity.

  19. The exchange across the tropical tropopause in overshooting convective cores

    Energy Technology Data Exchange (ETDEWEB)

    Rao, T.N.; Radhakrishna, B.; Mohan Satyanarayana, T.; Satheesh Kumar, S. [National Atmospheric Research Lab., Gadanki (India)

    2010-07-01

    Coordinated measurements of Indian MST radar and radiosonde during the passage of overshooting convective cores in SAFAR pilot campaign (May-November 2008) are utilized to quantify the mass flux across the tropopause and strength of the turbulence in up- and down-draft cores. The distribution of retrieved mass flux is found to be wide, ranging from -0.6 (downward flux) to 0.8 kg m{sup -2}s{sup -1} (upward flux). The net mass flux, is, however, from the troposphere to stratosphere, in spite of the existence of significant amount of downward flux. For the first time, the turbulence strength in the vicinity of the tropopause in convective cores is quantified. Large spectral widths with magnitudes >4 ms{sup -1} are observed during convection. However, such large spectral widths are rare and are observed only for 1.6% of total observations. The average spectral width (and also the variation or standard deviation) in draft cores is found to be {proportional_to}4.5 times larger than that in fair-weather. The turbulence strength in updraft cores is much higher than that of in downdraft cores. The mean (median) spectral width in updraft cores is larger by {proportional_to}0.8 ms{sup -1} (a factor of {proportional_to}2) than that of in downdraft cores. The turbulence strength does not show any systematic variation with the intensity of convection in both up- and down-draft cores. The distributions and mean values of mass flux and turbulence strength obtained in the present study will be useful to quantify the STE due to direct intrusion of mass by overshooting convection and the exchange of constituents (in particular water vapor) due to turbulence in a better way. (orig.)

  20. Physical properties of dense cores in Orion B9

    CERN Document Server

    Miettinen, Oskari; Haikala, Lauri K; Juvela, Mika

    2010-01-01

    We aim to determine the physical and chemical properties of dense cores in Orion B9. We observed the NH3(1,1) and (2,2), and the N2H+(3-2) lines towards the submm peak positions. These data are used in conjunction with our LABOCA 870 micron dust continuum data. The gas kinetic temperature in the cores is between ~9.4-13.9 K. The non-thermal velocity dispersion is subsonic in most of the cores. The non-thermal linewidth in protostellar cores appears to increase with increasing bolometric luminosity. The core masses are very likely drawn from the same parent distribution as the core masses in Orion B North. Starless cores in the region are likely to be gravitationally bound, and thus prestellar. Some of the cores have a lower radial velocity than the systemic velocity of the region, suggesting that they are members of the "low-velocity part" of Orion B. The observed core-separation distances deviate from the corresponding random-like model distributions. The distances between the nearest-neighbours are comparab...

  1. Mechanisms and Geochemical Models of Core Formation

    CERN Document Server

    Rubie, David C

    2015-01-01

    The formation of the Earth's core is a consequence of planetary accretion and processes in the Earth's interior. The mechanical process of planetary differentiation is likely to occur in large, if not global, magma oceans created by the collisions of planetary embryos. Metal-silicate segregation in magma oceans occurs rapidly and efficiently unlike grain scale percolation according to laboratory experiments and calculations. Geochemical models of the core formation process as planetary accretion proceeds are becoming increasingly realistic. Single stage and continuous core formation models have evolved into multi-stage models that are couple to the output of dynamical models of the giant impact phase of planet formation. The models that are most successful in matching the chemical composition of the Earth's mantle, based on experimentally-derived element partition coefficients, show that the temperature and pressure of metal-silicate equilibration must increase as a function of time and mass accreted and so m...

  2. Modeling and Simulations for the High Flux Isotope Reactor Cycle 400

    Energy Technology Data Exchange (ETDEWEB)

    Ilas, Germina [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). High Flux Isotope Reactor (HFIR); Chandler, David [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). High Flux Isotope Reactor (HFIR); Ade, Brian J [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). High Flux Isotope Reactor (HFIR); Sunny, Eva E [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). High Flux Isotope Reactor (HFIR); Betzler, Benjamin R [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). High Flux Isotope Reactor (HFIR); Pinkston, Daniel [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). High Flux Isotope Reactor (HFIR)

    2015-03-01

    A concerted effort over the past few years has been focused on enhancing the core model for the High Flux Isotope Reactor (HFIR), as part of a comprehensive study for HFIR conversion from high-enriched uranium (HEU) to low-enriched uranium (LEU) fuel. At this time, the core model used to perform analyses in support of HFIR operation is an MCNP model for the beginning of Cycle 400, which was documented in detail in a 2005 technical report. A HFIR core depletion model that is based on current state-of-the-art methods and nuclear data was needed to serve as reference for the design of an LEU fuel for HFIR. The recent enhancements in modeling and simulations for HFIR that are discussed in the present report include: (1) revision of the 2005 MCNP model for the beginning of Cycle 400 to improve the modeling data and assumptions as necessary based on appropriate primary reference sources HFIR drawings and reports; (2) improvement of the fuel region model, including an explicit representation for the involute fuel plate geometry that is characteristic to HFIR fuel; and (3) revision of the Monte Carlo-based depletion model for HFIR in use since 2009 but never documented in detail, with the development of a new depletion model for the HFIR explicit fuel plate representation. The new HFIR models for Cycle 400 are used to determine various metrics of relevance to reactor performance and safety assessments. The calculated metrics are compared, where possible, with measurement data from preconstruction critical experiments at HFIR, data included in the current HFIR safety analysis report, and/or data from previous calculations performed with different methods or codes. The results of the analyses show that the models presented in this report provide a robust and reliable basis for HFIR analyses.

  3. A BRIGHTEST CLUSTER GALAXY WITH AN EXTREMELY LARGE FLAT CORE

    Energy Technology Data Exchange (ETDEWEB)

    Postman, Marc; Coe, Dan; Koekemoer, Anton; Bradley, Larry [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21208 (United States); Lauer, Tod R. [National Optical Astronomy Observatory, P.O. Box 26732, Tucson, AZ 85726 (United States); Donahue, Megan [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Graves, Genevieve [Department of Astronomy, 601 Campbell Hall, University of California, Berkeley, CA 94720 (United States); Moustakas, John [Center for Astrophysics and Space Sciences, University of California, La Jolla, CA 92093 (United States); Ford, Holland C.; Lemze, Doron; Medezinski, Elinor [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Grillo, Claudio [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Mariesvej 30, DK-2100 Copenhagen (Denmark); Zitrin, Adi [University of Heidelberg, Albert-Ueberle-Str. 2, D-69120 Heidelberg (Germany); Broadhurst, Tom [Department of Theoretical Physics, University of the Basque Country UPV/EHU, Bizkaia, E-48940 Leioa (Spain); Moustakas, Leonidas [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Ascaso, Begona [Instituto de Astrofisica de Andalucia (CSIC), C/Camino Bajo de Huetor 24, E-18008 Granada (Spain); Kelson, Daniel [The Observatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)

    2012-09-10

    Hubble Space Telescope images of the galaxy cluster A2261, obtained as part of the Cluster Lensing And Supernova survey with Hubble, show that the brightest galaxy in the cluster, A2261-BCG, has the largest core yet detected in any galaxy. The cusp radius of A2261-BCG is 3.2 kpc, twice as big as the next largest core known, and {approx}3 Multiplication-Sign bigger than those typically seen in the most luminous brightest cluster galaxies. The morphology of the core in A2261-BCG is also unusual, having a completely flat interior surface brightness profile, rather than the typical shallow cusp rising into the center. This implies that the galaxy has a core with constant or even centrally decreasing stellar density. Interpretation of the core as an end product of the 'scouring' action of a binary supermassive black hole implies a total black hole mass {approx}10{sup 10} M{sub Sun} from the extrapolation of most relationships between core structure and black hole mass. The core falls 1{sigma} above the cusp radius versus galaxy luminosity relation. Its large size in real terms, and the extremely large black hole mass required to generate it, raises the possibility that the core has been enlarged by additional processes, such as the ejection of the black holes that originally generated the core. The flat central stellar density profile is consistent with this hypothesis. The core is also displaced by 0.7 kpc from the center of the surrounding envelope, consistent with a local dynamical perturbation of the core.

  4. Inner core structure behind the PKP core phase triplication

    NARCIS (Netherlands)

    Blom, Nienke A.; Deuss, Arwen; Paulssen, Hanneke; Waszek, Lauren

    2015-01-01

    The structure of the Earth's inner core is not well known between depths of ∼100–200 km beneath the inner core boundary. This is a result of the PKP core phase triplication and the existence of strong precursors to PKP phases, which hinder the measurement of inner core compressional PKIKP waves at e

  5. Inner core structure behind the PKP core phase triplication

    NARCIS (Netherlands)

    Blom, Nienke A.; Deuss, Arwen; Paulssen, Hanneke; Waszek, Lauren

    The structure of the Earth's inner core is not well known between depths of ∼100–200 km beneath the inner core boundary. This is a result of the PKP core phase triplication and the existence of strong precursors to PKP phases, which hinder the measurement of inner core compressional PKIKP waves at

  6. Pressure Core Characterization

    Science.gov (United States)

    Santamarina, J. C.

    2014-12-01

    Natural gas hydrates form under high fluid pressure and low temperature, and are found in permafrost, deep lakes or ocean sediments. Hydrate dissociation by depressurization and/or heating is accompanied by a multifold hydrate volume expansion and host sediments with low permeability experience massive destructuration. Proper characterization requires coring, recovery, manipulation and testing under P-T conditions within the stability field. Pressure core technology allows for the reliable characterization of hydrate bearing sediments within the stability field in order to address scientific and engineering needs, including the measurement of parameters used in hydro-thermo-mechanical analyses, and the monitoring of hydrate dissociation under controlled pressure, temperature, effective stress and chemical conditions. Inherent sampling effects remain and need to be addressed in test protocols and data interpretation. Pressure core technology has been deployed to study hydrate bearing sediments at several locations around the world. In addition to pressure core testing, a comprehensive characterization program should include sediment analysis, testing of reconstituted specimens (with and without synthetic hydrate), and in situ testing. Pressure core characterization technology can be used to study other gas-charged formations such as deep sea sediments, coal bed methane and gas shales.

  7. SMA millimeter observations of Hot Molecular Cores

    CERN Document Server

    Hernández-Hernández, Vicente; Kurtz, Stan; Garay, Guido

    2014-01-01

    We present Submillimeter Array observations, in the 1.3 mm continuum and the CH_3CN(12-11) line of 17 hot molecular cores associated with young high-mass stars. The angular resolution of the observations ranges from 1".0 to 4".0. The continuum observations reveal large (>3500 AU) dusty structures with gas masses from 7 to 375 Msun, that probably surround multiple young stars. The CH_3CN line emission is detected toward all the molecular cores at least up to the K=6-component and is mostly associated with the emission peaks of the dusty objects. We used the multiple K-components of the CH_3CN and both the rotational diagram method and a simultaneous synthetic LTE model with the XCLASS program to estimate the temperatures and column densities of the cores. For all sources, we obtained reasonable fits from XCLASS by using a model that combines two components: an extended and warm envelope, and a compact hot core of molecular gas, suggesting internal heating by recently formed massive stars. The rotational temper...

  8. Abdominal mass

    Science.gov (United States)

    Mass in the abdomen ... care provider make a diagnosis. For example, the abdomen can be divided into four areas: Right-upper ... pain or masses include: Epigastric -- center of the abdomen just below the rib cage Periumbilical -- area around ...

  9. GREEN CORE HOUSE

    Directory of Open Access Journals (Sweden)

    NECULAI Oana

    2017-05-01

    Full Text Available The Green Core House is a construction concept with low environmental impact, having as main central element a greenhouse. The greenhouse has the innovative role to use the biomass energy provided by plants to save energy. Although it is the central piece, the greenhouse is not the most innovative part of the Green Core House, but the whole building ensemble because it integrates many other sustainable systems as "waste purification systems", "transparent photovoltaic panels" or "double skin façades".

  10. Birefringent hollow core fibers

    DEFF Research Database (Denmark)

    Roberts, John

    2007-01-01

    Hollow core photonic crystal fiber (HC-PCF), fabricated according to a nominally non-birefringent design, shows a degree of un-controlled birefringence or polarization mode dispersion far in excess of conventional non polarization maintaining fibers. This can degrade the output pulse in many...... and an increased overlap between the polarization modes at the glass interfaces. The interplay between these effects leads to a wavelength for optimum polarization maintenance, lambda(PM), which is detuned from the wavelength of highest birefringence. By a suitable fiber design involving antiresonance of the core...

  11. Birefringent hollow core fibers

    DEFF Research Database (Denmark)

    Roberts, John

    2007-01-01

    Hollow core photonic crystal fiber (HC-PCF), fabricated according to a nominally non-birefringent design, shows a degree of un-controlled birefringence or polarization mode dispersion far in excess of conventional non polarization maintaining fibers. This can degrade the output pulse in many...... and an increased overlap between the polarization modes at the glass interfaces. The interplay between these effects leads to a wavelength for optimum polarization maintenance, lambda(PM), which is detuned from the wavelength of highest birefringence. By a suitable fiber design involving antiresonance of the core...

  12. Simulating an Exploding Fission-Bomb Core

    Science.gov (United States)

    Reed, Cameron

    2016-03-01

    A time-dependent desktop-computer simulation of the core of an exploding fission bomb (nuclear weapon) has been developed. The simulation models a core comprising a mixture of two isotopes: a fissile one (such as U-235) and an inert one (such as U-238) that captures neutrons and removes them from circulation. The user sets the enrichment percentage and scattering and fission cross-sections of the fissile isotope, the capture cross-section of the inert isotope, the number of neutrons liberated per fission, the number of ``initiator'' neutrons, the radius of the core, and the neutron-reflection efficiency of a surrounding tamper. The simulation, which is predicated on ordinary kinematics, follows the three-dimensional motions and fates of neutrons as they travel through the core. Limitations of time and computer memory render it impossible to model a real-life core, but results of numerous runs clearly demonstrate the existence of a critical mass for a given set of parameters and the dramatic effects of enrichment and tamper efficiency on the growth (or decay) of the neutron population. The logic of the simulation will be described and results of typical runs will be presented and discussed.

  13. Blue straggler formation at core collapse

    CERN Document Server

    Banerjee, Sambaran

    2016-01-01

    Among the most striking feature of blue straggler stars (BSS) is the presence of multiple sequences of BSSs in the colour-magnitude diagrams (CMDs) of several globular clusters. It is often envisaged that such a multiple BSS sequence would arise due a recent core collapse of the host cluster, triggering a number of stellar collisions and binary mass transfers simultaneously over a brief episode of time. Here we examine this scenario using direct N-body computations of moderately massive star clusters (of order 10^4 Msun ). As a preliminary attempt, these models are initiated with approx. 8-10 Gyr old stellar population and King profiles of high concentrations, being "tuned" to undergo core collapse quickly. BSSs are indeed found to form in a "burst" at the onset of the core collapse and several of such BS-bursts occur during the post-core-collapse phase. In those models that include a few percent primordial binaries, both collisional and binary BSSs form after the onset of the (near) core-collapse. However, t...

  14. An unbiased survey for dense cores in the Lynds 1630 molecular cloud

    Science.gov (United States)

    Lada, Elizabeth A.; Bally, John; Stark, Antony A.

    1991-01-01

    An unbiased, systematic survey for dense cores within the L1630 (Orion B) molecular cloud has been completed. This survey provides the first complete census of dense (n greater tha 10,000/cu cm) cores within a molecular cloud. To identify the dense gas, 3.6 square degrees of the L1630 cloud were surveyed in the J = 2-1 transition of CS. CS emission was detected over 10 percent of the area surveyed, and this emission is not uniformly distributed throughout the cloud but is confined to 42 dense cores. The size, shape, velocity dispersion, and mass of these cores are examined. Comparison of the mass contained within dense cores with the total gas mass within the surveyed region, estimated from CO emission, reveals that the dense cores constitute only a small fraction (not greater than 19 percent) of the total cloud mass.

  15. A Survey of Dense Cores in the Orion B Cloud

    Science.gov (United States)

    Ikeda, Norio; Kitamura, Yoshimi; Sunada, Kazuyoshi

    2009-02-01

    We have carried out an H13CO+(J = 1 - 0) core survey in a large area of 1 deg2, covering most of the dense region in the Orion B molecular cloud, using the Nobeyama 45 m radio telescope with the 25-BEam Array Receiver System. We cataloged 151 dense cores using the clumpfind method. The cores have mean radius, velocity width, and mass of 0.10 ± 0.02 pc, 0.53 ± 0.15 km s-1, and 8.1 ± 6.4 M sun, respectively, which are very similar to those in the Orion A cloud. We examined the spatial relation between our H13CO+ cores and the 850 μm cores observed by Johnstone and colleagues in 2001 and 2006, and found that there are two types of spatial relationships: H13CO+ cores with and without the 850 μm cores. Since the mean density of the 850 μm cores is higher than that of the H13CO+ cores, we can interpret the H13CO+ cores with 850 μm cores as being more centrally concentrated and hence more evolved, compared with those without. Considering the relationship between the masses of the H13CO+ and 850 μm cores, we estimate the 850 μm core mass function (CMF) using the H13CO+ CMF through the generalization of the confusion model proposed by Ikeda and colleagues in 2007. Our predicted 850 μm CMF is found to be quite consistent with that directly derived by Johnstone and colleagues. Furthermore, we predict the initial mass function (IMF) by the generalized confusion model assuming a star formation efficiency of 40% for the H13CO+ cores, and found that our predicted IMF is consistent with the Galactic field-averaged IMF within uncertainties. This agreement may indicate that the origin of the IMF goes back to the cloud structures with densities of less than 104 cm-3.

  16. On the Coagulation and Size Distribution of Pressure Confined Cores

    CERN Document Server

    Huang, Xu; Lin, D N C

    2013-01-01

    Observations of the Pipe Nebula have led to the discovery of dense starless cores. The mass of most cores is too small for their self gravity to hold them together. Instead, they are thought to be pressure confined. The observed dense cores' mass function (CMF) matches well with the initial mass function (IMF) of stars in young clusters. Similar CMF's are observed in other star forming regions such as the Aquila Nebula, albeit with some dispersion. The shape of these CMF provides important clues to the competing physical processes which lead to star formation and its feedback on the interstellar media. In this paper, we investigate the dynamical origin of the the mass function of starless cores which are confined by a warm, less dense medium. We consider the coagulation between the cold cores and their ablation due to Kelvin-Helmholtz instability induced by their relative motion through the warm medium. We are able to reproduce the observed CMF among the starless cores in the Pipe nebula. Our results indicate...

  17. DESIGN STUDY FOR A LOW-ENRICHED URANIUM CORE FOR THE HIGH FLUX ISOTOPE REACTOR, ANNUAL REPORT FOR FY 2010

    Energy Technology Data Exchange (ETDEWEB)

    Cook, David Howard [ORNL; Freels, James D [ORNL; Ilas, Germina [ORNL; Jolly, Brian C [ORNL; Miller, James Henry [ORNL; Primm, Trent [ORNL; Renfro, David G [ORNL; Sease, John D [ORNL; Pinkston, Daniel [ORNL

    2011-02-01

    This report documents progress made during FY 2010 in studies of converting the High Flux Isotope Reactor (HFIR) from high enriched uranium (HEU) fuel to low enriched uranium (LEU) fuel. Conversion from HEU to LEU will require a change in fuel form from uranium oxide to a uranium-molybdenum alloy. With axial and radial grading of the fuel foil and an increase in reactor power to 100 MW, calculations indicate that the HFIR can be operated with LEU fuel with no degradation in performance to users from the current level. Studies are reported of support to a thermal hydraulic test loop design, the implementation of finite element, thermal hydraulic analysis capability, and infrastructure tasks at HFIR to upgrade the facility for operation at 100 MW. A discussion of difficulties with preparing a fuel specification for the uranium-molybdenum alloy is provided. Continuing development in the definition of the fuel fabrication process is described.

  18. Investigation of EAS cores

    Science.gov (United States)

    Shaulov, S. B.; Beyl, P. F.; Beysembaev, R. U.; Beysembaeva, E. A.; Bezshapov, S. P.; Borisov, A. S.; Cherdyntceva, K. V.; Chernyavsky, M. M.; Chubenko, A. P.; Dalkarov, O. D.; Denisova, V. G.; Erlykin, A. D.; Kabanova, N. V.; Kanevskaya, E. A.; Kotelnikov, K. A.; Morozov, A. E.; Mukhamedshin, R. A.; Nam, R. A.; Nesterova, N. M.; Nikolskaya, N. M.; Pavluchenko, V. P.; Piskal, V. V.; Puchkov, V. S.; Pyatovsky, S. E.; Ryabov, V. A.; Sadykov, T. Kh.; Schepetov, A. L.; Smirnova, M. D.; Stepanov, A. V.; Uryson, A. V.; Vavilov, Yu. N.; Vildanov, N. G.; Vildanova, L. I.; Zayarnaya, I. S.; Zhanceitova, J. K.; Zhukov, V. V.

    2017-06-01

    The development of nuclear-electromagnetic cascade models in air in the late forties have shown informational content of the study of cores of extensive air showers (EAS). These investigations were the main goal in different experiments which were carried out over many years by a variety of methods. Outcomes of such investigations obtained in the HADRON experiment using an X-ray emulsion chamber (XREC) as a core detector are considered. The Ne spectrum of EAS associated with γ-ray families, spectra of γ-rays (hadrons) in EAS cores and the Ne dependence of the muon number, ⟨Nμ⟩, in EAS with γ-ray families are obtained for the first time at energies of 1015-1017 eV with this method. A number of new effects were observed, namely, an abnormal scaling violation in hadron spectra which are fundamentally different from model predictions, an excess of muon number in EAS associated with γ-ray families, and the penetrating component in EAS cores. It is supposed that the abnormal behavior of γ-ray spectra and Ne dependence of the muon number are explained by the emergence of a penetrating component in the 1st PCR spectrum `knee' range. Nuclear and astrophysical explanations of the origin of the penetrating component are discussed. The necessity of considering the contribution of a single close cosmic-ray source to explain the PCR spectrum in the knee range is noted.

  19. Some Core Contested Concepts

    Science.gov (United States)

    Chomsky, Noam

    2015-01-01

    Core concepts of language are highly contested. In some cases this is legitimate: real empirical and conceptual issues arise. In other cases, it seems that controversies are based on misunderstanding. A number of crucial cases are reviewed, and an approach to language is outlined that appears to have strong conceptual and empirical motivation, and…

  20. Looking for Core Values

    Science.gov (United States)

    Carter, Margie

    2010-01-01

    People who view themselves as leaders, not just managers or teachers, are innovators who focus on clarifying core values and aligning all aspects of the organization with these values to grow their vision. A vision for an organization can't be just one person's idea. Visions grow by involving people in activities that help them name and create…

  1. Nucleosome Core Particle

    Science.gov (United States)

    1997-01-01

    Nucleosome Core Particle grown on STS-81. The fundamental structural unit of chromatin and is the basis for organization within the genome by compaction of DNA within the nucleus of the cell and by making selected regions of chromosomes available for transcription and replication. Principal Investigator's are Dr. Dan Carter and Dr. Gerard Bunick of New Century Pharmaceuticals.

  2. Investigation of EAS cores

    Directory of Open Access Journals (Sweden)

    Shaulov S.B.

    2017-01-01

    Full Text Available The development of nuclear-electromagnetic cascade models in air in the late forties have shown informational content of the study of cores of extensive air showers (EAS. These investigations were the main goal in different experiments which were carried out over many years by a variety of methods. Outcomes of such investigations obtained in the HADRON experiment using an X-ray emulsion chamber (XREC as a core detector are considered. The Ne spectrum of EAS associated with γ-ray families, spectra of γ-rays (hadrons in EAS cores and the Ne dependence of the muon number, ⟨Nμ⟩, in EAS with γ-ray families are obtained for the first time at energies of 1015–1017 eV with this method. A number of new effects were observed, namely, an abnormal scaling violation in hadron spectra which are fundamentally different from model predictions, an excess of muon number in EAS associated with γ-ray families, and the penetrating component in EAS cores. It is supposed that the abnormal behavior of γ-ray spectra and Ne dependence of the muon number are explained by the emergence of a penetrating component in the 1st PCR spectrum ‘knee’ range. Nuclear and astrophysical explanations of the origin of the penetrating component are discussed. The necessity of considering the contribution of a single close cosmic-ray source to explain the PCR spectrum in the knee range is noted.

  3. The Earth's Core.

    Science.gov (United States)

    Jeanloz, Raymond

    1983-01-01

    The nature of the earth's core is described. Indirect evidence (such as that determined from seismological data) indicates that it is an iron alloy, solid toward its center but otherwise liquid. Evidence also suggests that it is the turbulent flow of the liquid that generates the earth's magnetic field. (JN)

  4. Some Core Contested Concepts

    Science.gov (United States)

    Chomsky, Noam

    2015-01-01

    Core concepts of language are highly contested. In some cases this is legitimate: real empirical and conceptual issues arise. In other cases, it seems that controversies are based on misunderstanding. A number of crucial cases are reviewed, and an approach to language is outlined that appears to have strong conceptual and empirical motivation, and…

  5. Languages for Dublin Core.

    Science.gov (United States)

    Baker, Thomas

    1998-01-01

    Focusing on languages for the Dublin Core, examines the experience of some related ways to seek semantic interoperability through simplicity: planned languages, interlingua constructs, and pidgins. Also defines the conceptual and organizational problem of maintaining a metadata standard in multiple languages. (AEF)

  6. Core calculations of JMTR

    Energy Technology Data Exchange (ETDEWEB)

    Nagao, Yoshiharu [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment

    1998-03-01

    In material testing reactors like the JMTR (Japan Material Testing Reactor) of 50 MW in Japan Atomic Energy Research Institute, the neutron flux and neutron energy spectra of irradiated samples show complex distributions. It is necessary to assess the neutron flux and neutron energy spectra of an irradiation field by carrying out the nuclear calculation of the core for every operation cycle. In order to advance core calculation, in the JMTR, the application of MCNP to the assessment of core reactivity and neutron flux and spectra has been investigated. In this study, in order to reduce the time for calculation and variance, the comparison of the results of the calculations by the use of K code and fixed source and the use of Weight Window were investigated. As to the calculation method, the modeling of the total JMTR core, the conditions for calculation and the adopted variance reduction technique are explained. The results of calculation are shown. Significant difference was not observed in the results of neutron flux calculations according to the difference of the modeling of fuel region in the calculations by K code and fixed source. The method of assessing the results of neutron flux calculation is described. (K.I.)

  7. The core and cosmopolitans

    DEFF Research Database (Denmark)

    Dahlander, Linus; Frederiksen, Lars

    2012-01-01

    Users often interact and help each other solve problems in communities, but few scholars have explored how these relationships provide opportunities to innovate. We analyze the extent to which people positioned within the core of a community as well as people that are cosmopolitans positioned...

  8. Schumpeter's core works revisited

    DEFF Research Database (Denmark)

    Andersen, Esben Sloth

    2012-01-01

    This paper organises Schumpeter’s core books in three groups: the programmatic duology,the evolutionaryeconomic duology,and the socioeconomic synthesis. By analysing these groups and their interconnections from the viewpoint of modern evolutionaryeconomics,the paper summarises resolved problems...

  9. Adult educators' core competences

    DEFF Research Database (Denmark)

    Wahlgren, Bjarne

    2016-01-01

    environment as well as the kind of adult education concerned (e.g. basic education, work-related education etc.). However, it seems that it is possible to identify certain competence requirements which transcend national, cultural and functional boundaries. This research note summarises these common or “core...

  10. Adult educators' core competences

    DEFF Research Database (Denmark)

    Wahlgren, Bjarne

    2016-01-01

    environment as well as the kind of adult education concerned (e.g. basic education, work-related education etc.). However, it seems that it is possible to identify certain competence requirements which transcend national, cultural and functional boundaries. This research note summarises these common or “core...

  11. Measurement of delta13C and delta18O Isotopic Ratios of CaCO3 by a Thermoquest Finnigan GasBench II Delta Plus XL Continous Flow Isotope Ratio Mass Spectrometer with Application to Devils Hole Core DH-11 Calcite

    Science.gov (United States)

    Revesz, Kinga M.; Landwehr, Jurate Maciunas; Keybl, Jaroslav Edward

    2001-01-01

    A new method was developed to analyze the stable carbon and oxygen isotope ratios of small samples (400?20 ?g) of calcium carbonate. This new method streamlines the classical phosphoric acid - calcium carbonate (H3PO4 - CaCO3) reaction method by making use of a Thermoquest-Finnigan GasBench II preparation device and a Delta Plus XL continuous flow isotope ratio mass spectrometer. To obtain reproducible and accurate results, optimal conditions for the H3PO4 - CaCO3 reaction had to be determined. At the acid-carbonate reaction temperature suggested by the equipment manufacturer, the oxygen isotope ratio results were unsatisfactory (standard deviation () greater than 1.5 per mill), probably because of a secondary reaction. When the acid-carbonate reaction temperature was lowered to 26?C and the reaction time was increased to 24 hours, the precision of the carbon and oxygen isotope ratios for duplicate analyses improved to 0.1 and 0.2 per mill, respectively. The method was tested by analyzing calcite from Devils Hole, Nevada, which was formed by precipitation from ground water onto the walls of a sub-aqueous cavern during the last 500,000 years. Isotope-ratio values previously had been obtained by the classical method for Devils Hole core DH-11. The DH-11 core had been recently re-sampled, and isotope-ratio values were obtained using this new method. The results were comparable to those obtained by the classical method. The consistency of the isotopic results is such that an alignment offset could be identified in the re-sampled core material, a cutting error that was then independently confirmed. The reproducibility of the isotopic values is demonstrated by a correlation of approximately 0.96 for both isotopes, after correcting for an alignment offset. This result indicates that the new method is a viable alternative to the classical method. In particular, the new method requires less sample material permitting finer resolution and allows automation of some processes

  12. The clinical significance of lobular neoplasia on breast core biopsy.

    Science.gov (United States)

    Karabakhtsian, Rouzan G; Johnson, Ronald; Sumkin, Jules; Dabbs, David J

    2007-05-01

    A core biopsy diagnosis of atypical ductal epithelial hyperplasia is upstaged on follow-up excisional biopsy (FUEB) to in situ or invasive carcinoma in about 20% of cases, thus prompting a FUEB. In contrast, upstaging information for a core biopsy diagnosis of pure lobular neoplasia (LN), without mass lesions or other risk-associated lesions is less clear. In this retrospective study, we report the largest consecutive series of patients who had a breast core biopsy diagnosis of LN and a FUEB. Core needle breast biopsies with a diagnosis of LN were retrieved from our files for the period 1999 to 2005, yielding 110 patients. One hundred and one patients had a follow-up surgical excision. Cases of LN with coexisting high-risk lesions (n=9, 10%) were excluded from the study. Patients with associated mass lesions all had benign findings (n=15, 16%) and had no impact on the study results. The remaining 77 core biopsies had no masses or risk lesions and were mammographically Breast Imaging Reporting and Data System 4 (BIRADS) for microcalcifications. Overall, 8/77 (10%) of patients with a radiographic BIRADS 4 image with calcifications and a core biopsy diagnosis of LN on core biopsy were upstaged on FUEB to ductal carcinoma in situ or invasive carcinoma. The numbers upstaged from core biopsies were as follows: atypical lobular hyperplasia (ALH) 4/52 (8%), mixed ALH/lobular carcinoma in situ (LCIS) 1/9 (10%), and pure LCIS 3/16 (19%). A core biopsy of LCIS with neoplastic epithelial calcifications was nearly 3 times more likely to be upstaged on FUEB compared with ALH. We conclude that a finding of LN on breast core biopsy in a patient with a BIRADS 4 image and calcifications is associated with a risk of 8% to 19% of upstaging to a treatable disease on FUEB.

  13. The JCMT Gould Belt Survey: Dense Core Clusters in Orion B

    CERN Document Server

    Kirk, H; Di Francesco, J; Lane, J; Buckle, J; Berry, D S; Broekhoven-Fiene, H; Currie, M J; Fich, M; Hatchell, J; Jenness, T; Mottram, J C; Nutter, D; Pattle, K; Pineda, J E; Quinn, C; Salji, C; Tisi, S; Hogerheijde, M R; Ward-Thompson, D

    2016-01-01

    The JCMT Gould Belt Legacy Survey obtained SCUBA-2 observations of dense cores within three sub-regions of Orion B: LDN 1622, NGC 2023/2024, and NGC 2068/2071, all of which contain clusters of cores. We present an analysis of the clustering properties of these cores, including the two-point correlation function and Cartwright's Q parameter. We identify individual clusters of dense cores across all three regions using a minimal spanning tree technique, and find that in each cluster, the most massive cores tend to be centrally located. We also apply the independent M-Sigma technique and find a strong correlation between core mass and the local surface density of cores. These two lines of evidence jointly suggest that some amount of mass segregation in clusters has happened already at the dense core stage.

  14. The JCMT Gould Belt Survey: Dense Core Clusters in Orion B

    Science.gov (United States)

    Kirk, H.; Johnstone, D.; Di Francesco, J.; Lane, J.; Buckle, J.; Berry, D. S.; Broekhoven-Fiene, H.; Currie, M. J.; Fich, M.; Hatchell, J.; Jenness, T.; Mottram, J. C.; Nutter, D.; Pattle, K.; Pineda, J. E.; Quinn, C.; Salji, C.; Tisi, S.; Hogerheijde, M. R.; Ward-Thompson, D.; The JCMT Gould Belt Survey Team

    2016-04-01

    The James Clerk Maxwell Telescope Gould Belt Legacy Survey obtained SCUBA-2 observations of dense cores within three sub-regions of Orion B: LDN 1622, NGC 2023/2024, and NGC 2068/2071, all of which contain clusters of cores. We present an analysis of the clustering properties of these cores, including the two-point correlation function and Cartwright’s Q parameter. We identify individual clusters of dense cores across all three regions using a minimal spanning tree technique, and find that in each cluster, the most massive cores tend to be centrally located. We also apply the independent M-Σ technique and find a strong correlation between core mass and the local surface density of cores. These two lines of evidence jointly suggest that some amount of mass segregation in clusters has happened already at the dense core stage.

  15. Neutrino Masses

    CERN Document Server

    Weinheimer, Christian

    2013-01-01

    The various experiments on neutrino oscillation evidenced that neutrinos have indeed non-zero masses but cannot tell us the absolute neutrino mass scale. This scale of neutrino masses is very important for understanding the evolution and the structure formation of the universe as well as for nuclear and particle physics beyond the present Standard Model. Complementary to deducing constraints on the sum of all neutrino masses from cosmological observations two different methods to determine the neutrino mass scale in the laboratory are pursued: the search for neutrinoless double $\\beta$-decay and the direct neutrino mass search by investigating single $\\beta$-decays or electron captures. The former method is not only sensitive to neutrino masses but also probes the Majorana character of neutrinos and thus lepton number violation with high sensitivity. Currently quite a few experiments with different techniques are being constructed, commissioned or are even running, which aim for a sensitivity on the neutrino ...

  16. Contraction Signatures toward Dense Cores in the Perseus Molecular Cloud

    Science.gov (United States)

    Campbell, J. L.; Friesen, R. K.; Martin, P. G.; Caselli, P.; Kauffmann, J.; Pineda, J. E.

    2016-03-01

    We report the results of an HCO+ (3-2) and N2D+ (3-2) molecular line survey performed toward 91 dense cores in the Perseus molecular cloud using the James Clerk Maxwell Telescope, to identify the fraction of starless and protostellar cores with systematic radial motions. We quantify the HCO+ asymmetry using a dimensionless asymmetry parameter δv, and identify 20 cores with significant blue or red line asymmetries in optically thick emission indicative of collapsing or expanding motions, respectively. We separately fit the HCO+ profiles with an analytic collapse model and determine contraction (expansion) speeds toward 22 cores. Comparing the δv and collapse model results, we find that δv is a good tracer of core contraction if the optically thin emission is aligned with the model-derived systemic velocity. The contraction speeds range from subsonic (0.03 km s-1) to supersonic (0.4 km s-1), where the supersonic contraction speeds may trace global rather than local core contraction. Most cores have contraction speeds significantly less than their free-fall speeds. Only 7 of 28 starless cores have spectra well-fit by the collapse model, which more than doubles (15 of 28) for protostellar cores. Starless cores with masses greater than the Jeans mass (M/MJ > 1) are somewhat more likely to show contraction motions. We find no trend of optically thin non-thermal line width with M/MJ, suggesting that any undetected contraction motions are small and subsonic. Most starless cores in Perseus are either not in a state of collapse or expansion, or are in a very early stage of collapse.

  17. CONTRACTION SIGNATURES TOWARD DENSE CORES IN THE PERSEUS MOLECULAR CLOUD

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, J. L. [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George St., Toronto, Ontario, M5S 3H4 (Canada); Friesen, R. K. [Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George St., Toronto, Ontario, M5S 3H4 (Canada); Martin, P. G. [Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George St., Toronto, Ontario, M5S 3H8 (Canada); Caselli, P.; Pineda, J. E. [Max-Planck-Institut für extraterrestrische Physik (MPE), Gießenbachstrasse 1, D-85741 Garching (Germany); Kauffmann, J., E-mail: jessicalynn.campbell@mail.utoronto.ca [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany)

    2016-03-10

    We report the results of an HCO{sup +} (3–2) and N{sub 2}D{sup +} (3–2) molecular line survey performed toward 91 dense cores in the Perseus molecular cloud using the James Clerk Maxwell Telescope, to identify the fraction of starless and protostellar cores with systematic radial motions. We quantify the HCO{sup +} asymmetry using a dimensionless asymmetry parameter δ{sub v}, and identify 20 cores with significant blue or red line asymmetries in optically thick emission indicative of collapsing or expanding motions, respectively. We separately fit the HCO{sup +} profiles with an analytic collapse model and determine contraction (expansion) speeds toward 22 cores. Comparing the δ{sub v} and collapse model results, we find that δ{sub v} is a good tracer of core contraction if the optically thin emission is aligned with the model-derived systemic velocity. The contraction speeds range from subsonic (0.03 km s{sup −1}) to supersonic (0.4 km s{sup −1}), where the supersonic contraction speeds may trace global rather than local core contraction. Most cores have contraction speeds significantly less than their free-fall speeds. Only 7 of 28 starless cores have spectra well-fit by the collapse model, which more than doubles (15 of 28) for protostellar cores. Starless cores with masses greater than the Jeans mass (M/M{sub J} > 1) are somewhat more likely to show contraction motions. We find no trend of optically thin non-thermal line width with M/M{sub J}, suggesting that any undetected contraction motions are small and subsonic. Most starless cores in Perseus are either not in a state of collapse or expansion, or are in a very early stage of collapse.

  18. Application of Core Dynamics Modeling to Core-Mantle Interactions

    Science.gov (United States)

    Kuang, Weijia

    2003-01-01

    Observations have demonstrated that length of day (LOD) variation on decadal time scales results from exchange of axial angular momentum between the solid mantle and the core. There are in general four core-mantle interaction mechanisms that couple the core and the mantle. Of which, three have been suggested likely the dominant coupling mechanism for the decadal core-mantle angular momentum exchange, namely, gravitational core-mantle coupling arising from density anomalies in the mantle and in the core (including the inner core), the electromagnetic coupling arising from Lorentz force in the electrically conducting lower mantle (e.g. D-layer), and the topographic coupling arising from non-hydrostatic pressure acting on the core-mantle boundary (CMB) topography. In the past decades, most effort has been on estimating the coupling torques from surface geomagnetic observations (kinematic approach), which has provided insights on the core dynamical processes. In the meantime, it also creates questions and concerns on approximations in the studies that may invalidate the corresponding conclusions. The most serious problem is perhaps the approximations that are inconsistent with dynamical processes in the core, such as inconsistencies between the core surface flow beneath the CMB and the CMB topography, and that between the D-layer electric conductivity and the approximations on toroidal field at the CMB. These inconsistencies can only be addressed with numerical core dynamics modeling. In the past few years, we applied our MoSST (Modular, Scalable, Self-consistent and Three-dimensional) core dynamics model to study core-mantle interactions together with geodynamo simulation, aiming at assessing the effect of the dynamical inconsistencies in the kinematic studies on core-mantle coupling torques. We focus on topographic and electromagnetic core-mantle couplings and find that, for the topographic coupling, the consistency between the core flow and the CMB topography is

  19. Sterile neutrino oscillations in core-collapse supernova simulations

    CERN Document Server

    Warren, MacKenzie L; Mathews, Grant; Hidaka, Jun; Kajino, Toshitaka

    2014-01-01

    We have made core-collapse supernova simulations that allow oscillations between electron neutrinos (or their anti particles) with right-handed sterile neutrinos. We have considered a range of mixing angles and sterile neutrino masses including those consistent with sterile neutrinos as a dark matter candidate. We examine whether such oscillations can impact the core bounce and shock reheating in supernovae. We identify the optimum ranges of mixing angles and masses that can dramatically enhance the supernova explosion by efficiently transporting electron anti-neutrinos from the core to behind the shock where they provide additional heating leading to much larger explosion kinetic energies. We show that an interesting oscillation in the neutrino luminosity develops due to a cycle of depletion of the neutrino density by conversion to sterile neutrinos that shuts off the conversion, followed by a replenished neutrino density as neutrinos transport through the core.

  20. The AGB bump: a calibrator for the core mixing

    CERN Document Server

    Bossini, Diego; Salaris, Maurizio; Girardi, Léo; Montalbán, Josefina; Bressan, Alessandro; Marigo, Paola; Noels, Arlette

    2015-01-01

    The efficiency of convection in stars affects many aspects of their evolution and remains one of the key-open questions in stellar modelling. In particular, the size of the mixed core in core-He-burning low-mass stars is still uncertain and impacts the lifetime of this evolutionary phase and, e.g., the C/O profile in white dwarfs. One of the known observables related to the Horizontal Branch (HB) and Asymptotic Giant Branch (AGB) evolution is the AGB bump. Its luminosity depends on the position in mass of the helium-burning shell at its first ignition, that is affected by the extension of the central mixed region. In this preliminary work we show how various assumptions on near-core mixing and on the thermal stratification in the overshooting region affect the luminosity of the AGB bump, as well as the period spacing of gravity modes in core-He-burning models.

  1. The AGB bump: a calibrator for core mixing

    Science.gov (United States)

    Bossini, Diego; Miglio, Andrea; Salaris, Maurizio; Girardi, Léo; Montalbán, Josefina; Bressan, Alessandro; Marigo, Paola; Noels, Arlette

    2015-09-01

    The efficiency of convection in stars affects many aspects of their evolution and remains one of the key-open questions in stellar modelling. In particular, the size of the mixed core in core-He-burning low-mass stars is still uncertain and impacts the lifetime of this evolutionary phase and, e.g., the C/O profile in white dwarfs. One of the known observables related to the Horizontal Branch (HB) and Asymptotic Giant Branch (AGB) evolution is the AGB bump. Its luminosity depends on the position in mass of the helium-burning shell at its first ignition, that is affected by the extension of the central mixed region. In this preliminary work we show how various assumptions on near-core mixing and on the thermal stratification in the overshooting region affect the luminosity of the AGB bump, as well as the period spacing of gravity modes in core-He-burning models.

  2. The AGB bump: a calibrator for core mixing

    Directory of Open Access Journals (Sweden)

    Bossini Diego

    2015-01-01

    Full Text Available The efficiency of convection in stars affects many aspects of their evolution and remains one of the key-open questions in stellar modelling. In particular, the size of the mixed core in core-He-burning low-mass stars is still uncertain and impacts the lifetime of this evolutionary phase and, e.g., the C/O profile in white dwarfs. One of the known observables related to the Horizontal Branch (HB and Asymptotic Giant Branch (AGB evolution is the AGB bump. Its luminosity depends on the position in mass of the helium-burning shell at its first ignition, that is affected by the extension of the central mixed region. In this preliminary work we show how various assumptions on near-core mixing and on the thermal stratification in the overshooting region affect the luminosity of the AGB bump, as well as the period spacing of gravity modes in core-He-burning models.

  3. Evaluation of Treatments to Reduce Hardness of Agave americana Core

    Directory of Open Access Journals (Sweden)

    José A. Ramírez

    2006-01-01

    Full Text Available Agave americana contains inulin as storage carbohydrate. Therefore, agave is interesting to be used for the extraction of inulin by pressing. The yield of the process is low due to the high hardness of the core. The objective of this work was to evaluate pretreatments to reduce the hardness in the process of obtaining inulin by pressing. Treatments with water, sulphuric acid 1 % (by mass or sodium hydroxide 1 % (by mass were tested and optimized. The pretreatment of the core of A. americana with sulphuric acid 1 % allowed the reduction of hardness from 30 000 g to 2000 g of breaking force. The mathematical model obtained predicts an optimum processing at 84 °C during 75 min. The treatment with sulphuric acid 1 % also allows white core of A. americana to be obtained, while the other treatments provide yellow core. These results open a good alternative to obtain value added products from this resource.

  4. USGS Core Research Center (CRC) Collection of Core

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Core Research Center (CRC) was established in 1974 by the U.S. Geological Survey (USGS) to preserve valuable rock cores for use by scientists and educators from...

  5. Ice Cores of the National Ice Core Laboratory

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The U.S. National Ice Core Laboratory (NICL) is a facility for storing, curating, and studying ice cores recovered from the polar regions of the world. It provides...

  6. Core Outlet Temperature Study

    Energy Technology Data Exchange (ETDEWEB)

    Moisseytsev, A. [Argonne National Laboratory (ANL), Argonne, IL (United States); Hoffman, E. [Argonne National Laboratory (ANL), Argonne, IL (United States); Majumdar, S. [Argonne National Laboratory (ANL), Argonne, IL (United States)

    2008-07-28

    It is a known fact that the power conversion plant efficiency increases with elevation of the heat addition temperature. The higher efficiency means better utilization of the available resources such that higher output in terms of electricity production can be achieved for the same size and power of the reactor core or, alternatively, a lower power core could be used to produce the same electrical output. Since any nuclear power plant, such as the Advanced Burner Reactor, is ultimately built to produce electricity, a higher electrical output is always desirable. However, the benefits of the higher efficiency and electricity production usually come at a price. Both the benefits and the disadvantages of higher reactor outlet temperatures are analyzed in this work.

  7. Geomagnetism of earth's core

    Science.gov (United States)

    Benton, E. R.

    1983-01-01

    Instrumentation, analytical methods, and research goals for understanding the behavior and source of geophysical magnetism are reviewed. Magsat, launched in 1979, collected global magnetometer data and identified the main terrestrial magnetic fields. The data has been treated by representing the curl-free field in terms of a scalar potential which is decomposed into a truncated series of spherical harmonics. Solutions to the Laplace equation then extend the field upward or downward from the measurement level through intervening spaces with no source. Further research is necessary on the interaction between harmonics of various spatial scales. Attempts are also being made to analytically model the main field and its secular variation at the core-mantle boundary. Work is also being done on characterizing the core structure, composition, thermodynamics, energetics, and formation, as well as designing a new Magsat or a tethered satellite to be flown on the Shuttle.

  8. Geomagnetism of earth's core

    Science.gov (United States)

    Benton, E. R.

    1983-01-01

    Instrumentation, analytical methods, and research goals for understanding the behavior and source of geophysical magnetism are reviewed. Magsat, launched in 1979, collected global magnetometer data and identified the main terrestrial magnetic fields. The data has been treated by representing the curl-free field in terms of a scalar potential which is decomposed into a truncated series of spherical harmonics. Solutions to the Laplace equation then extend the field upward or downward from the measurement level through intervening spaces with no source. Further research is necessary on the interaction between harmonics of various spatial scales. Attempts are also being made to analytically model the main field and its secular variation at the core-mantle boundary. Work is also being done on characterizing the core structure, composition, thermodynamics, energetics, and formation, as well as designing a new Magsat or a tethered satellite to be flown on the Shuttle.

  9. MASS SPECTROMETER

    Science.gov (United States)

    White, F.A.

    1960-08-23

    A mass spectrometer is designed with a first adjustable magnetic field for resolving an ion beam into beams of selected masses, a second adjustable magnetic field for further resolving the ion beam from the first field into beams of selected masses, a thin foil disposed in the path of the beam between the first and second magnets to dissociate molecular ions incident thereon, an electrostatic field for further resolving the ion beam from the second field into beams of selected masses, and a detector disposed adjacent to the electrostatic field to receive the ion beam.

  10. Some core contested concepts.

    Science.gov (United States)

    Chomsky, Noam

    2015-02-01

    Core concepts of language are highly contested. In some cases this is legitimate: real empirical and conceptual issues arise. In other cases, it seems that controversies are based on misunderstanding. A number of crucial cases are reviewed, and an approach to language is outlined that appears to have strong conceptual and empirical motivation, and to lead to conclusions about a number of significant issues that differ from some conventional beliefs.

  11. Central core disease

    Directory of Open Access Journals (Sweden)

    Jungbluth Heinz

    2007-05-01

    Full Text Available Abstract Central core disease (CCD is an inherited neuromuscular disorder characterised by central cores on muscle biopsy and clinical features of a congenital myopathy. Prevalence is unknown but the condition is probably more common than other congenital myopathies. CCD typically presents in infancy with hypotonia and motor developmental delay and is characterized by predominantly proximal weakness pronounced in the hip girdle; orthopaedic complications are common and malignant hyperthermia susceptibility (MHS is a frequent complication. CCD and MHS are allelic conditions both due to (predominantly dominant mutations in the skeletal muscle ryanodine receptor (RYR1 gene, encoding the principal skeletal muscle sarcoplasmic reticulum calcium release channel (RyR1. Altered excitability and/or changes in calcium homeostasis within muscle cells due to mutation-induced conformational changes of the RyR protein are considered the main pathogenetic mechanism(s. The diagnosis of CCD is based on the presence of suggestive clinical features and central cores on muscle biopsy; muscle MRI may show a characteristic pattern of selective muscle involvement and aid the diagnosis in cases with equivocal histopathological findings. Mutational analysis of the RYR1 gene may provide genetic confirmation of the diagnosis. Management is mainly supportive and has to anticipate susceptibility to potentially life-threatening reactions to general anaesthesia. Further evaluation of the underlying molecular mechanisms may provide the basis for future rational pharmacological treatment. In the majority of patients, weakness is static or only slowly progressive, with a favourable long-term outcome.

  12. The Deuteration Clock for Massive Starless Cores

    Science.gov (United States)

    Kong, S.; Tan, J. C.; Caselli, P.; Fontani, F.

    2015-05-01

    To understand massive star formation requires study of its initial conditions. Two massive starless core candidates, C1-N & C1-S, have been detected in IRDC G028.37+00.07 in N2D+(3-2) with ALMA. From their line widths, either the cores are subvirial and are thus young structures on the verge of near free-fall collapse, or they are threaded by ˜1 mG B-fields that help support them in near virial equilibrium and potentially have older ages. We modeled the deuteration rate of N2H+ to constrain collapse rates of the cores. First, to measure their current deuterium fraction, D≡ [N2D+]/[N2H+], we observed multiple transitions of N2H+ and N2D+ with CARMA, SMA, JCMT, NRO 45 m and IRAM 30 m, to complement the ALMA data. For both cores we derived D ˜ 0.3, several orders of magnitude above the cosmic [D]/[H] ratio. We then carried out chemodynamical modeling, exploring how collapse rate relative to free-fall, αff, affects the level of D that is achieved from a given initial condition. To reach the observed D, most models require slow collapse with αff˜0.1, i.e., ˜1/10th of free-fall. This makes it more likely that the cores have been able to reach a near virial equilibrium state and we predict that strong B-fields will eventually be detected. The methods developed here will be useful for measurement of the pre-stellar core mass function.

  13. Core-seis: a code for LMFBR core seismic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Chellapandi, P.; Ravi, R.; Chetal, S.C.; Bhoje, S.B. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Reactor Group

    1995-12-31

    This paper deals with a computer code CORE-SEIS specially developed for seismic analysis of LMFBR core configurations. For demonstrating the prediction capability of the code, results are presented for one of the MONJU reactor core mock ups which deals with a cluster of 37 subassemblies kept in water. (author). 3 refs., 7 figs., 2 tabs.

  14. Core Exercises: Why You Should Strengthen Your Core Muscles

    Science.gov (United States)

    Healthy Lifestyle Fitness You know core exercises are good for you — but do you include core exercises in your fitness routine? Here's why ... 18, 2014 Original article: http://www.mayoclinic.org/healthy-lifestyle/fitness/in-depth/core-exercises/art-20044751 . Mayo Clinic Footer Legal Conditions and ...

  15. Cusp-core transformations in dwarf galaxies: observational predictions

    CERN Document Server

    Teyssier, Romain; Dubois, Yohan; Read, Justin

    2012-01-01

    The presence of a dark matter core in the central kiloparsec of many dwarf galaxies has been a long standing problem in galaxy formation theories based on the standard cold dark matter paradigm. Recent cosmological simulations, based on Smooth Particle Hydrodynamics and rather strong feedback recipes have shown that it was indeed possible to form extended dark matter cores using baryonic processes related to a more realistic treatment of the interstellar medium. Using adaptive mesh refinement, together with a new, stronger supernovae feedback scheme that we have recently implemented in the RAMSES code, we show that it is also possible to form a prominent dark matter core within the well-controlled framework of an isolated, initially cuspy, 10 billion solar masses dark matter halo. Although our numerical experiment is idealized, it allows a clean and unambiguous identification of the dark matter core formation process. Our dark matter inner profile is well fitted by a pseudo-isothermal profile with a core radi...

  16. Cores in Dwarf Galaxies from Fermi Repulsion

    CERN Document Server

    Randall, Lisa; Unwin, James

    2016-01-01

    We show that Fermi repulsion can lead to cored density profiles in dwarf galaxies for sub-keV fermionic dark matter. We treat the dark matter as a quasi-degenerate self-gravitating Fermi gas and calculate its density profile assuming hydrostatic equilibrium. We find that suitable dwarf galaxy cores of larger than 130 pc can be achieved for fermion dark matter with mass in the range 70 eV - 400 eV. While in conventional dark matter scenarios, such sub-keV thermal dark matter would be excluded by free streaming bounds, the constraints are ameliorated in models with dark matter at lower temperature than conventional thermal scenarios, such as the Flooded Dark Matter model that we have previously considered. Modifying the arguments of Tremaine and Gunn we derive a conservative lower bound on the mass of fermionic dark matter of 70 eV and a stronger lower bound from Lyman-$\\alpha$ clouds of about 470 eV, leading to slightly smaller cores than have been observed. We comment on this result and how the tension is rel...

  17. Vibroacoustic Characterization of Corrugated-Core and Honeycomb-Core Sandwich Panels

    Science.gov (United States)

    Allen, Albert; Schiller, Noah

    2016-01-01

    The vibroacoustic characteristics of two candidate launch vehicle fairing structures, corrugated- core and honeycomb-core sandwich designs, were studied. The study of these structures has been motivated by recent risk reduction efforts focused on mitigating high noise levels within the payload bays of large launch vehicles during launch. The corrugated-core sandwich concept is of particular interest as a dual purpose structure due to its ability to harbor resonant noise control systems without appreciably adding mass or taking up additional volume. Specifically, modal information, wavelength dispersion, and damping were determined from a series of vibrometer measurements and subsequent analysis procedures carried out on two test panels. Numerical and analytical modeling techniques were also used to assess assumed material properties and to further illuminate underlying structural dynamic aspects. Results from the tests and analyses described herein may serve as a reference for additional vibroacoustic studies involving these or similar structures.

  18. ICF Core Sets for stroke

    National Research Council Canada - National Science Library

    Szilvia Geyh; Alarcos Cieza; Jan Schouten; Hugh Dickson; Peter Frommelt; Zaliha Omar; Nenad Kostanjsek; Haim Ring; Gerold Stucki

    2004-01-01

    Objective: To report on the results of the consensus process integrating evidence from preliminary studies to develop the first version of the Comprehensive ICF Core Set and the Brief ICF Core Set for stroke. Methods...

  19. Misalignment of Magnetic Fields and Outflows in Protostellar Cores

    CERN Document Server

    Hull, Charles L H; Bolatto, Alberto D; Bower, Geoffrey C; Carpenter, John M; Crutcher, Richard M; Fiege, Jason D; Franzmann, Erica; Hakobian, Nicholas S; Heiles, Carl; Houde, Martin; Hughes, A Meredith; Jameson, Katherine; Kwon, Woojin; Lamb, James W; Looney, Leslie W; Matthews, Brenda C; Mundy, Lee; Pillai, Thushara; Pound, Marc W; Stephens, Ian W; Tobin, John J; Vaillancourt, John E; Volgenau, N H; Wright, Melvyn C H

    2012-01-01

    Theoretical models of star formation generally assume that bipolar outflows are parallel to the mean magnetic-field direction in protostellar cores. Here we present results of \\lambda1.3 mm dust polarization observations toward 16 nearby, low-mass protostars, mapped with ~2.5" resolution at CARMA. The results show that magnetic fields in protostellar cores on scales of ~1000 AU are not tightly aligned with outflows from the protostars. If one assumes that outflows emerge along the rotation axes of circumstellar disks, then our results imply that these disks are not aligned with the fields in the cores from which they formed.

  20. Hydrodynamic simulations of the core helium flash

    CERN Document Server

    Mocak, M; Weiss, A; Kifonidis, K; 10.1017/S1743921308022813

    2009-01-01

    We describe and discuss hydrodynamic simulations of the core helium flash using an initial model of a 1.25 M_sol star with a metallicity of 0.02 near at its peak. Past research concerned with the dynamics of the core helium flash is inconclusive. Its results range from a confirmation of the standard picture, where the star remains in hydrostatic equilibrium during the flash (Deupree 1996), to a disruption or a significant mass loss of the star (Edwards 1969; Cole & Deupree 1980). However, the most recent multidimensional hydrodynamic study (Dearborn 2006) suggests a quiescent behavior of the core helium flash and seems to rule out an explosive scenario. Here we present partial results of a new comprehensive study of the core helium flash, which seem to confirm this qualitative behavior and give a better insight into operation of the convection zone powered by helium burning during the flash. The hydrodynamic evolution is followed on a computational grid in spherical coordinates using our new version of th...

  1. Effect of Rotation in Cloud Core Collapse

    Science.gov (United States)

    Tsuribe, T.

    stage by rapid growth of a nonspherical first core. Second, to mimic fragmentation processes of primordial clouds, the equation of state is approximated by a simple polytropic relation with γ ˜ 1.1. A series of numerical and semianalytical calculations of the rotating collapse of an initially spherical cloud shows a criterion for fragmentation of rotating polytropic cloud cores with γ=1.1. Fragmentation during core collapse is not expected to take place if the cloud thermal energy is greater than 0.3 times its gravitational energy at the initial stage of runaway collapse. The collapse of the central small core will not be halted by centrifugal force since a nonaxisymmetric waves will appear and the flow will converge to a self-similar flow until γ exceeds 4/3. Finally, we take into account the detailed non-equilibrium chemical reactions for primordial gas that consists of pure hydrogen. The parameters of the collapse and the condition of the fragmentation are compared with those of isothermal clouds. It is shown that the geometrical flatness of the central region of the disc is a good indicator for predicting whether the clouds fragment or not. If the flatness is greater than the critical value, ˜ 4π, a cloud fragments into filaments and blobs. On the other hand, if the flatness is smaller than the critical value, fragmentation is not expected before the central core formation even if the cooling is efficient and the total mass becomes much greater than the local Jeans mass at the center.

  2. Rotationally induced fragmentation in the prestellar core L1544

    Energy Technology Data Exchange (ETDEWEB)

    Klapp, Jaime; Zavala, Miguel [Departamento de Física, Instituto Nacional de Investigaciones Nucleares (ININ), Km. 36.5, Carretera México-Toluca, La Marquesa 52750, Estado de México (Mexico); Sigalotti, Leonardo Di G.; Peña-Polo, Franklin; Troconis, Jorge [Centro de Física, Instituto Venezolano de Investigaciones Científicas (IVIC), Apartado Postal 20632, Caracas 1020A (Venezuela, Bolivarian Republic of)

    2014-01-10

    Recent observations indicate that there is no correlation between the level of turbulence and fragmentation in detected protostellar cores, suggesting that turbulence works mainly before gravitationally bound prestellar cores form and that their inner parts are likely to be velocity coherent. Based on this evidence, we simulate the collapse and fragmentation of an isolated, initially centrally condensed, uniformly rotating core of total mass M = 5.4 M {sub ☉}, using the smoothed particle hydrodynamics code GADGET-2 modified with the inclusion of sink particles, in order to compare the statistical properties of the resulting stellar ensembles with previous gravoturbulent fragmentation models. The initial conditions are intended to fit the observed properties of the prestellar core L1544. We find that for ratios of the rotational to the gravitational energy β ≥ 0.05, a massive disk is formed at the core center from which a central primary condenses after ∼50 kyr. Soon thereafter the disk fragments into secondary protostars, consistent with an intermediate mode of star formation in which groups of 10-100 stars form from a single core. The models predict peak accretion rates between ∼10{sup –5} and 10{sup –4} M {sub ☉} yr{sup –1} for all stars and reproduce many of the statistical properties predicted from gravoturbulent fragmentation, suggesting that on the small scales of low-mass, dense cores these are independent of whether the contracting gas is turbulent or purely rotating.

  3. The Dynamics and Chemistry of Massive Starless Cores

    Science.gov (United States)

    Tan, J. C.; Kong, S.; Butler, M. J.; Caselli, P.; Fontani, F.

    2013-10-01

    How do massive stars form? They may be born from massive pre-stellar gas cores that are much more massive than the Jeans mass. The Turbulent Core Accretion model invokes such cores as being in approximate virial and pressure equilibrium with their surrounding clump medium. Their internal pressure is provided by a combination of turbulence and magnetic fields. On the other hand, the Competitive Accretion model requires strongly sub-virial initial conditions that then lead to extensive fragmentation to the thermal Jeans scale, with high-mass stars later forming by competitive Bondi-Hoyle accretion. To test these models, we have identified four prime examples of massive (˜ 100 M⊙) clumps from mid-infrared (MIR) extinction mapping of Infrared Dark Clouds (IRDCs). At ˜16″ resolution, we found high deuteration fractions of N2H+ in these objects, consistent with them being starless. We then observed these 4 clumps with ALMA in Cycle 0 to probe the N2D+(3-2) line at ˜2″ resolution, finding 6 N2D+ cores. Their observed velocity dispersions and sizes are broadly consistent with the predictions of the Turbulent Core model of virialized, magnetized (with Alfvén Mach number mA ˜ 1), self-gravitating cores that are bounded by the high pressures of their surrounding clumps. However, the most massive core with ˜ 60 M⊙, appears to require moderately enhanced magnetic fields to be in virial equilibrium, implying mA ≃ 0.3. If confirmed, this suggests magnetic fields play a greater role than turbulence in setting the initial conditions of massive star formation. In this case the timescale for the core to be assembled may be significantly longer than a local dynamical or free-fall time. This is consistent with astrochemical modeling of the deuteration ages of the cores, which indicates a core age similar to the ambipolar diffusion time.

  4. Hollow-Core Fiber Lamp

    Science.gov (United States)

    Yi, Lin (Inventor); Tjoelker, Robert L. (Inventor); Burt, Eric A. (Inventor); Huang, Shouhua (Inventor)

    2016-01-01

    Hollow-core capillary discharge lamps on the millimeter or sub-millimeter scale are provided. The hollow-core capillary discharge lamps achieve an increased light intensity ratio between 194 millimeters (useful) and 254 millimeters (useless) light than conventional lamps. The capillary discharge lamps may include a cone to increase light output. Hollow-core photonic crystal fiber (HCPCF) may also be used.

  5. On core stability and extendability

    OpenAIRE

    Shellshear, Evan

    2007-01-01

    This paper investigates conditions under which the core of a TU cooperative game is stable. In particular the author extends the idea of extendability to find new conditions under which the core is stable. It is also shown that these new conditions are not necessary for core stability.

  6. Dual-core Itanium Processor

    CERN Multimedia

    2006-01-01

    Intel’s first dual-core Itanium processor, code-named "Montecito" is a major release of Intel's Itanium 2 Processor Family, which implements the Intel Itanium architecture on a dual-core processor with two cores per die (integrated circuit). Itanium 2 is much more powerful than its predecessor. It has lower power consumption and thermal dissipation.

  7. On core stability and extendability

    OpenAIRE

    Shellshear, Evan

    2007-01-01

    This paper investigates conditions under which the core of a TU cooperative game is stable. In particular the author extends the idea of extendability to find new conditions under which the core is stable. It is also shown that these new conditions are not necessary for core stability.

  8. Differential Stoichiometry among Core Ribosomal Proteins

    Science.gov (United States)

    Slavov, Nikolai; Semrau, Stefan; Airoldi, Edoardo; Budnik, Bogdan; van Oudenaarden, Alexander

    2015-01-01

    Summary Understanding the regulation and structure of ribosomes is essential to understanding protein synthesis and its dysregulation in disease. While ribosomes are believed to have a fixed stoichiometry among their core ribosomal proteins (RPs), some experiments suggest a more variable composition. Testing such variability requires direct and precise quantification of RPs. We used mass spectrometry to directly quantify RPs across monosomes and polysomes of mouse embryonic stem cells (ESC) and budding yeast. Our data show that the stoichiometry among core RPs in wild-type yeast cells and ESC depends both on the growth conditions and on the number of ribosomes bound per mRNA. Furthermore, we find that the fitness of cells with a deleted RP-gene is inversely proportional to the enrichment of the corresponding RP in polysomes. Together, our findings support the existence of ribosomes with distinct protein composition and physiological function. PMID:26565899

  9. Axion dark matter: strings and their cores

    Energy Technology Data Exchange (ETDEWEB)

    Fleury, Leesa [McGill University, Department of Physics,3600 rue University, Montréal QC H3A 2T8 (Canada); Moore, Guy D. [Institut für Kernphysik, Technische Universität Darmstadt,Schlossgartenstraße 2, D-64289 Darmstadt (Germany)

    2016-01-04

    Axions constitute a well-motivated dark matter candidate, and if PQ symmetry breaking occurred after inflation, it should be possible to make a clean prediction for the relation between the axion mass and the axion dark matter density. We show that axion (or other global) string networks in 3D have a network density that depends logarithmically on the string separation-to-core ratio. This logarithm would be about 10 times larger in axion cosmology than what we can achieve in numerical simulations. We simulate axion production in the early Universe, finding that, for the separation-to-core ratios we can achieve, the changing density of the network has little impact on the axion production efficiency.

  10. How chameleons core dwarfs with cusps

    CERN Document Server

    Lombriser, Lucas

    2014-01-01

    The presence of a scalar field that couples nonminimally and universally to matter can enhance gravitational forces on cosmological scales while restoring general relativity in the Solar neighborhood. In the intermediate regime, kinematically inferred masses experience an additional radial dependence with respect to the underlying distribution of matter, which is caused by the increment of gravitational forces with increasing distance from the Milky Way center. The same effect can influence the internal kinematics of subhalos and cause cuspy matter distributions to appear core-like. Specializing to the chameleon model as a worked example, we demonstrate this effect by tracing the scalar field from the outskirts of the Milky Way halo to its interior, simultaneously fitting observed velocity dispersions of chemo-dynamically discriminated red giant populations in the Fornax and Sculptor dwarf spheroidals. Whereas in standard gravity these observations suggest that the matter distribution of the dwarfs is cored, ...

  11. Massive molecular cloud cores and activities of star formation

    Institute of Scientific and Technical Information of China (English)

    Zhou Wu-Fei; Wu Yue-Fang; Wei Yue; Ju Bing-Gang

    2005-01-01

    We have mapped 23 sources in the J=1-0 lines of 12CO, 13CO and C18O with the 13.7-m telescope at Qinghai station of Purple Mountain Observatory. The samples were chosen from the massive star formation regions whose single point lines have the broad-wing profile. The mapping shows that 12 clouds have cores and 5 outflows were identified with the 12CO J=1-0 lines. Among the 12 cores, systematic velocity shifts were found in 2 cores, and blue asymmetric double-peak profile of 12CO line was found in IRAS 19529+2704, indicating that it may be an infall candidate. Physical parameters of the cores and outflows were derived from the local thermodynamic equilibrium assumption. The masses range from ~ 9.4 × 102M⊙ to ~ 2.2 × 105M⊙. The hydrogen molecule densities range from ~ 3.4 × 102cm-3 to~ 1.2 × 104cm-3. The molecular outflows have masses larger than 3.5M⊙, and kinetic energies greater than 0.9× 1038J.The outflows have significantly greater masses and kinetic energies than those from low-mass young stellar objects(YSOs). For the cores, 2MASS data are available, dozens of 2MASS sources with different colour indices and brightness are often found around IRAS source, among which the reddest 2MASS source is always within the IRAS error ellipse thus probably corresponds to the IRAS source.

  12. Winning Cores in Parity Games

    DEFF Research Database (Denmark)

    Vester, Steen

    2016-01-01

    We introduce the novel notion of winning cores in parity games and develop a deterministic polynomial-time under-approximation algorithm for solving parity games based on winning core approximation. Underlying this algorithm are a number properties about winning cores which are interesting...... in their own right. In particular, we show that the winning core and the winning region for a player in a parity game are equivalently empty. Moreover, the winning core contains all fatal attractors but is not necessarily a dominion itself. Experimental results are very positive both with respect to quality...

  13. Super-Earths as Failed Cores in Orbital Migration Traps

    Science.gov (United States)

    Hasegawa, Yasuhiro

    2016-11-01

    I explore whether close-in super-Earths were formed as rocky bodies that failed to grow fast enough to become the cores of gas giants before the natal protostellar disk dispersed. I model the failed cores’ inward orbital migration in the low-mass or type I regime to stopping points at distances where the tidal interaction with the protostellar disk applies zero net torque. The three kinds of migration traps considered are those due to the dead zone's outer edge, the ice line, and the transition from accretion to starlight as the disk's main heat source. As the disk disperses, the traps move toward final positions near or just outside 1 au. Planets at this location exceeding about 3 M ⊕ open a gap, decouple from their host traps, and migrate inward in the high-mass or type II regime to reach the vicinity of the star. I synthesize the population of planets that formed in this scenario, finding that a fraction of the observed super-Earths could have been failed cores. Most super-Earths that formed this way have more than 4 M ⊕, so their orbits when the disks dispersed were governed by type II migration. These planets have solid cores surrounded by gaseous envelopes. Their subsequent photoevaporative mass loss is most effective for masses originally below about 6 M ⊕. The failed core scenario suggests a division of the observed super-Earth mass-radius diagram into five zones according to the inferred formation history.

  14. SMA millimeter observations of hot molecular cores

    Energy Technology Data Exchange (ETDEWEB)

    Hernández-Hernández, Vicente; Zapata, Luis; Kurtz, Stan [Centro de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Apdo. Postal 3-72 (Xangari), 58090 Morelia, Michoacán (Mexico); Garay, Guido, E-mail: v.hernandez@crya.unam.mx [Departamento de Astronomía, Universidad de Chile, Camino del Observatorio 1515, Las Condes, Santiago (Chile)

    2014-05-01

    We present Submillimeter Array observations in the 1.3 mm continuum and the CH{sub 3}CN (12 {sub K}-11 {sub K}) line of 17 hot molecular cores associated with young high-mass stars. The angular resolution of the observations ranges from 1.''0 to 4.''0. The continuum observations reveal large (>3500 AU) dusty structures with gas masses from 7 to 375 M {sub ☉}, which probably surround multiple young stars. The CH{sub 3}CN line emission is detected toward all the molecular cores at least up to the K = 6 component and is mostly associated with the emission peaks of the dusty objects. We used the multiple K-components of the CH{sub 3}CN and both the rotational diagram method and a simultaneous synthetic local thermodynamic equilibrium model with the XCLASS program to estimate the temperatures and column densities of the cores. For all sources, we obtained reasonable fits from XCLASS by using a model that combines two components: an extended and warm envelope and a compact hot core of molecular gas, suggesting internal heating by recently formed massive stars. The rotational temperatures lie in the range of 40-132 K and 122-485 K for the extended and compact components, respectively. From the continuum and CH{sub 3}CN results, we infer fractional abundances from 10{sup –9} to 10{sup –7} toward the compact inner components, which increase with the rotational temperature. Our results agree with a chemical scenario in which the CH{sub 3}CN molecule is efficiently formed in the gas phase above 100-300 K, and its abundance increases with temperature.

  15. Models of the earth's core

    Science.gov (United States)

    Stevenson, D. J.

    1981-01-01

    Combined inferences from seismology, high-pressure experiment and theory, geomagnetism, fluid dynamics, and current views of terrestrial planetary evolution lead to models of the earth's core with five basic properties. These are that core formation was contemporaneous with earth accretion; the core is not in chemical equilibrium with the mantle; the outer core is a fluid iron alloy containing significant quantities of lighter elements and is probably almost adiabatic and compositionally uniform; the more iron-rich inner solid core is a consequence of partial freezing of the outer core, and the energy release from this process sustains the earth's magnetic field; and the thermodynamic properties of the core are well constrained by the application of liquid-state theory to seismic and labroatory data.

  16. The dynamical fingerprint of core scouring in massive elliptical galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, J.; Saglia, R. P.; Bender, R.; Erwin, P.; Fabricius, M., E-mail: jthomas@mpe.mpg.de [Max Planck-Institute for extraterrestrial Physics, P.O. Box 1312, Giessenbachstr. 1, D-85741 Garching (Germany)

    2014-02-10

    The most massive elliptical galaxies have low-density centers or cores that differ dramatically from the high-density centers of less massive ellipticals and bulges of disk galaxies. These cores have been interpreted as the result of mergers of supermassive black hole binaries, which depopulate galaxy centers by gravitationally slingshotting central stars toward large radii. Such binaries naturally form in mergers of luminous galaxies. Here, we analyze the population of central stellar orbits in 11 massive elliptical galaxies that we observed with the integral field spectrograph SINFONI at the European Southern Observatory Very Large Telescope. Our dynamical analysis is orbit-based and includes the effects of a central black hole, the mass distribution of the stars, and a dark matter halo. We show that the use of integral field kinematics and the inclusion of dark matter is important to conclude on the distribution of stellar orbits in galaxy centers. Six of our galaxies are core galaxies. In these six galaxies, but not in the galaxies without cores, we detect a coherent lack of stars on radial orbits in the core region and a uniform excess of radial orbits outside of it: when scaled by the core radius r{sub b} , the radial profiles of the classical anisotropy parameter β(r) are nearly identical in core galaxies. Moreover, they quantitatively match the predictions of black hole binary simulations, providing the first convincing dynamical evidence for core scouring in the most massive elliptical galaxies.

  17. Fingerprinting Hydrogen in Core-Collapse Supernovae

    Science.gov (United States)

    Nance, Sarafina; Parrent, Jerod; Soderberg, Alicia Margarita

    2016-01-01

    This is a preliminary report on the mass of remaining hydrogen envelopes for stars massive enough to explode under core collapse. Using the stellar evolution code, MESA, our initial findings suggest that a significant fraction of massive stars with M_ZAMS = 20-60 Msun lose all but 10^-3 Msun -10^-1 Msun as they near eventual core collapse. This result is dependent on the mass-loss prescription, degree of rotation, metallicity, rates of nuclear burning in the core, and the final stellar configuration. Nevertheless, each of our test cases include a few stars that retain trace amounts of surface hydrogen, which would then be detected as faint H in type IIb/Ib/Ic supernova spectra. We also compare our findings to the progenitor candidate identified for iPTF13bvn using the most recent photometric corrections. We agree with the previous conclusion found by Groh et al. (2013) that the progenitor had an initial mass of 32 Msun, but now with an additional condition of 0.06 Msun of hydrogen on its surface just prior to the explosion. We demonstrate through our study that not all Type Ib supernovae are fully devoid of hydrogen at the time of explosion, which has implications for the nature of the progenitor star and thus provides impetus for a revised classification scheme for 'stripped envelope' supernovae. This work was supported in part by the NSF REU and DoD ASSURE programs under NSF grant no. 1262851 and by the Smithsonian Institution.

  18. Complex coacervate core micelles.

    Science.gov (United States)

    Voets, Ilja K; de Keizer, Arie; Cohen Stuart, Martien A

    2009-01-01

    In this review we present an overview of the literature on the co-assembly of neutral-ionic block, graft, and random copolymers with oppositely charged species in aqueous solution. Oppositely charged species include synthetic (co)polymers of various architectures, biopolymers - such as proteins, enzymes and DNA - multivalent ions, metallic nanoparticles, low molecular weight surfactants, polyelectrolyte block copolymer micelles, metallo-supramolecular polymers, equilibrium polymers, etcetera. The resultant structures are termed complex coacervate core/polyion complex/block ionomer complex/interpolyelectrolyte complex micelles (or vesicles); i.e., in short C3Ms (or C3Vs) and PIC, BIC or IPEC micelles (and vesicles). Formation, structure, dynamics, properties, and function will be discussed. We focus on experimental work; theory and modelling will not be discussed. Recent developments in applications and micelles with heterogeneous coronas are emphasized.

  19. Understanding core conductor fabrics

    Energy Technology Data Exchange (ETDEWEB)

    Swenson, D E, E-mail: deswenson@affinity-esd.com [Affinity Static Control Consulting, LLC 2609 Quanah Drive, Round Rock, Texas, 78681 (United States)

    2011-06-23

    ESD Association standard test method ANSI/ESD STM2.1 - Garments (STM2.1), provides electrical resistance test procedures that are applicable for materials and garments that have surface conductive or surface dissipative properties. As has been reported in other papers over the past several years{sup 1} fabrics are now used in many industries for electrostatic control purposes that do not have surface conductive properties and therefore cannot be evaluated using the procedures in STM2.1{sup 2}. A study was conducted to compare surface conductive fabrics with samples of core conductor fibre based fabrics in order to determine differences and similarities with regards to various electrostatic properties. This work will be used to establish a new work item proposal within WG-2, Garments, in the ESD Association Standards Committee in the USA.

  20. Growth outside the core.

    Science.gov (United States)

    Zook, Chris; Allen, James

    2003-12-01

    Growth in an adjacent market is tougher than it looks; three-quarters of the time, the effort fails. But companies can change those odds dramatically. Results from a five-year study of corporate growth conducted by Bain & Company reveal that adjacency expansion succeeds only when built around strong core businesses that have the potential to become market leaders. And the best place to look for adjacency opportunities is inside a company's strongest customers. The study also found that the most successful companies were able to consistently, profitably outgrow their rivals by developing a formula for pushing out the boundaries of their core businesses in predictable, repeatable ways. Companies use their repeatability formulas to expand into any number of adjacencies. Some companies make repeated geographic moves, as Vodafone has done in expanding from one geographic market to another over the past 13 years, building revenues from $1 billion in 1990 to $48 billion in 2003. Others apply a superior business model to new segments. Dell, for example, has repeatedly adapted its direct-to-customer model to new customer segments and new product categories. In other cases, companies develop hybrid approaches. Nike executed a series of different types of adjacency moves: it expanded into adjacent customer segments, introduced new products, developed new distribution channels, and then moved into adjacent geographic markets. The successful repeaters in the study had two common characteristics. First, they were extraordinarily disciplined, applying rigorous screens before they made an adjacency move. This discipline paid off in the form of learning curve benefits, increased speed, and lower complexity. And second, in almost all cases, they developed their repeatable formulas by studying their customers and their customers' economics very, very carefully.

  1. Imaging the Moon's Core with Seismology

    Science.gov (United States)

    Weber, Renee C.; Lin, Pei-Ying Patty; Garnero, Ed J.; Williams, Quetin C.; Lognonne, Philippe

    2011-01-01

    Constraining the structure of the lunar core is necessary to improve our understanding of the present-day thermal structure of the interior and the history of a lunar dynamo, as well as the origin and thermal and compositional evolution of the Moon. We analyze Apollo deep moonquake seismograms using terrestrial array processing methods to search for the presence of reflected and converted energy from the lunar core. Although moonquake fault parameters are not constrained, we first explore a suite of theoretical focal spheres to verify that fault planes exist that can produce favorable core reflection amplitudes relative to direct up-going energy at the Apollo stations. Beginning with stacks of event seismograms from the known distribution of deep moonquake clusters, we apply a polarization filter to account for the effects of seismic scattering that (a) partitions energy away from expected components of ground motion, and (b) obscures all but the main P- and S-wave arrivals. The filtered traces are then shifted to the predicted arrival time of a core phase (e.g. PcP) and stacked to enhance subtle arrivals associated with the Moon s core. This combination of filtering and array processing is well suited for detecting deep lunar seismic reflections, since we do not expect scattered wave energy from near surface (or deeper) structure recorded at varying epicentral distances and stations from varying moonquakes at varying depths to stack coherently. Our results indicate the presence of a solid inner and fluid outer core, overlain by a partial-melt-containing boundary layer (Table 1). These layers are consistently observed among stacks from four classes of reflections: P-to-P, S-to-P, P-to-S, and S-to-S, and are consistent with current indirect geophysical estimates of core and deep mantle properties, including mass, moment of inertia, lunar laser ranging, and electromagnetic induction. Future refinements are expected following the successful launch of the GRAIL lunar

  2. Cusp-core problem and strong gravitational lensing

    Institute of Scientific and Technical Information of China (English)

    Nan Li; Da-Ming Chen

    2009-01-01

    Cosmological numerical simulations of galaxy formation have led to the cuspy density profile of a pure cold dark matter halo toward the center,which is in sharp contradiction with the observations of the rotation curves of cold dark matter-dominated dwarf and low surface brightness disk galaxies,with the latter tending to favor mass profiles with a fiat central core.Many efforts have been devoted to resolving this cusp-core problem in recent years,among them,baryon-cold dark matter interactions are considered to be the main physical mechanisms erasing the cold dark matter (CDM) cusp into a flat core in the centers of all CDM halos.Clearly,baryon-cold dark matter interactions are not customized only for CDM-dominated disk galaxies,but for all types,including giant ellipticals.We first fit the most recent high resolution observations of rotation curves with the Burkert profile,then use the constrained core size-halo mass relation to calculate the lensing frequency,and compare the predicted results with strong lensing observations.Unfortunately,it turns out that the core size constrained from rotation curves ofdisk galaxies cannot be extrapolated to giant ellipticals.We conclude that,in the standard cosmological paradigm,baryon-cold dark matter interactions are not universal mechanisms for galaxy formation,and therefore,they cannot be true solutions to the cusp-core problem.

  3. The dynamics of massive starless cores with ALMA

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Jonathan C. [Departments of Astronomy and Physics, University of Florida, Gainesville, FL 32611 (United States); Kong, Shuo; Butler, Michael J. [Department of Astronomy, University of Florida, Gainesville, FL 32611 (United States); Caselli, Paola [School of Physics and Astronomy, The University of Leeds, Leeds LS2 9JT (United Kingdom); Fontani, Francesco [INAF-Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, I-50125 Firenze (Italy)

    2013-12-20

    How do stars that are more massive than the Sun form, and thus how is the stellar initial mass function (IMF) established? Such intermediate- and high-mass stars may be born from relatively massive pre-stellar gas cores, which are more massive than the thermal Jeans mass. The turbulent core accretion model invokes such cores as being in approximate virial equilibrium and in approximate pressure equilibrium with their surrounding clump medium. Their internal pressure is provided by a combination of turbulence and magnetic fields. Alternatively, the competitive accretion model requires strongly sub-virial initial conditions that then lead to extensive fragmentation to the thermal Jeans scale, with intermediate- and high-mass stars later forming by competitive Bondi-Hoyle accretion. To test these models, we have identified four prime examples of massive (∼100 M {sub ☉}) clumps from mid-infrared extinction mapping of infrared dark clouds. Fontani et al. found high deuteration fractions of N{sub 2}H{sup +} in these objects, which are consistent with them being starless. Here we present ALMA observations of these four clumps that probe the N{sub 2}D{sup +} (3-2) line at 2.''3 resolution. We find six N{sub 2}D{sup +} cores and determine their dynamical state. Their observed velocity dispersions and sizes are broadly consistent with the predictions of the turbulent core model of self-gravitating, magnetized (with Alfvén Mach number m{sub A} ∼ 1) and virialized cores that are bounded by the high pressures of their surrounding clumps. However, in the most massive cores, with masses up to ∼60 M {sub ☉}, our results suggest that moderately enhanced magnetic fields (so that m{sub A} ≅ 0.3) may be needed for the structures to be in virial and pressure equilibrium. Magnetically regulated core formation may thus be important in controlling the formation of massive cores, inhibiting their fragmentation, and thus helping to establish the stellar IMF.

  4. Advances in core drilling technology

    Science.gov (United States)

    Holdsworth, G.

    Some notable technical advances in drill design were reported at the meeting, held in Canada August 30-September 1, 1982, at the University of Calgary. Chief amongst these was a battery powered, computer assisted electromechanical core drill which has recently been used by the Danes in Greenland to continuously core to the base of the ice sheet at 2038 m. This is the deepest coring operation so far on the Greenland ice sheet. (The record for deep glacier drilling is held by the U.S. Army Cold Regions Research and Engineering Laboratory for the continuous coring through 2164 m of ice to bedrock at Byrd Station, Antarctica, in 1968). In early 1982, a current Soviet core drilling operation was reported to be at a depth of 2000 m at Vostok station, Antarctica, where the total ice thickness is about 4000 m; the goal of core drilling the entire ice thickness there could be achieved before the end of 1983.

  5. The initial conditions of isolated star formation - X. A suggested evolutionary diagram for prestellar cores

    CERN Document Server

    Simpson, R J; Nutter, D; Ward-Thompson, D; Whitworth, A P

    2011-01-01

    We propose an evolutionary path for prestellar cores on the radius-mass diagram, which is analogous to stellar evolutionary paths on the Hertzsprung-Russell Diagram. Using James Clerk Maxwell Telescope (JCMT) observations of L1688 in the Ophiuchus star-forming complex, we analyse the HCO+ (J=4\\rightarrow3) spectral line profiles of prestellar cores. We find that of the 58 cores observed, 14 show signs of infall in the form of a blue-asymmetric double-peaked line profile. These 14 cores all lie beyond the Jeans mass line for the region on a radius-mass plot. Furthermore another 10 cores showing tentative signs of infall, in their spectral line profile shapes, appear on or just over the Jeans mass line. We therefore propose the manner in which a prestellar core evolves across this diagram. We hypothesise that a core is formed in the low-mass, low-radius region of the plot. It then accretes quasistatically, increasing in both mass and radius. When it crosses the limit of gravitational instability it begins to co...

  6. Mass metrology

    CERN Document Server

    Gupta, S V

    2012-01-01

    This book presents the practical aspects of mass measurements. Concepts of gravitational, inertial and conventional mass and details of the variation of acceleration of gravity are described. The Metric Convention and International Prototype Kilogram and BIPM standards are described. The effect of change of gravity on the indication of electronic balances is derived with respect of latitude, altitude and earth topography. The classification of weights by OIML is discussed. Maximum permissible errors in different categories of weights prescribed by national and international organizations are p

  7. Synthetic Observations of Magnetic Fields in Protostellar Cores

    CERN Document Server

    Lee, Joyce W Y; Offner, Stella S R

    2016-01-01

    The role of magnetic fields in the early stages of star formation is not well constrained. In order to discriminate between different star formation models, we analyze 3D magnetohydrodynamic simulations of low-mass cores and explore the correlation between magnetic field orientation and outflow orientation over time. We produce synthetic observations of dust polarization at resolutions comparable to millimeter-wave dust polarization maps observed by CARMA and compare these with 2D visualizations of projected magnetic field and column density. Cumulative distribution functions of the projected angle between the magnetic field and outflow show different degrees of alignment in simulations with differing mass-to-flux ratios. The distribution function for the less magnetized core agrees with observations finding random alignment between outflow and field orientations, while the more magnetized core exhibits stronger alignment. We find that fractional polarization increases when the system is viewed such that the ...

  8. 13CO mapping study for massive molecular cloud cores

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Using the newly installed SIS receiving system on the 13.7 m telescope at Qinghai Station of PMO, United Radio Astronomy of CAS, CO isotope 13 CO J=1-0 and C18 O J=1-0 lines were observed for thr ee sources S241, S39 and ON3. Results show that the three sources have massive cor es, of which the size is ~2-5 pc, masses are ~103-104 M⊙. The wid t hs of lines are also larger than those in low mass cores. And high velocity char acteristics were observed for all the sources. The V LSR distribution p resents rotation of the core in ON3. And all the three cores contain deeply embe dded forming massive stars. The young stellar objects in S241 and ON3 seem to be moving away from their birth sites.

  9. Radiocarbon analyses along the EDML ice core in Antarctica

    NARCIS (Netherlands)

    van de Wal, R.S.W.; Meijer, H.A.J.; van Rooij, M.; van der Veen, C.

    2007-01-01

    Samples, 17 in total, from the EDML core drilled at Kohnen station Antarctica are analysed for 14CO and 14CO2 with a dry-extraction technique in combination with accelerator mass spectrometry. Results of the in situ produced 14CO fraction show a very low concentration of in situ produced 14CO. Despi

  10. Radiocarbon analyses along the EDML ice core in Antarctica

    NARCIS (Netherlands)

    Van de Wal, R. S. W.; Meijer, H. A. J.; De Rooij, M.; Van der Veen, C.

    2007-01-01

    Samples, 17 in total, from the EDML core drilled at Kohnen station Antarctica are analysed for (CO)-C-14 and (CO2)-C-14 with a dry-extraction technique in combination with accelerator mass spectrometry. Results of the in situ produced (CO)-C-14 fraction show a very low concentration of in situ produ

  11. Information Technology, Core Competencies, and Sustained Competitive Advantage.

    Science.gov (United States)

    Byrd, Terry Anthony

    2001-01-01

    Presents a model that depicts a possible connection between competitive advantage and information technology. Focuses on flexibility of the information technology infrastructure as an enabler of core competencies, especially mass customization and time-to-market, that have a relationship to sustained competitive advantage. (Contains 82…

  12. Misalignment of magnetic fields and outflows in protostellar cores

    NARCIS (Netherlands)

    Hull, Charles L. H.; Plambeck, Richard L.; Bolatto, Alberto D.; Bower, Geoffrey C.; Carpenter, John M.; Crutcher, Richard M.; Fiege, Jason D.; Franzmann, Erica; Hakobian, Nicholas S.; Heiles, Carl; Houde, Martin; Hughes, A. Meredith; Jameson, Katherine; Kwon, Woojin; Lamb, James W.; Looney, Leslie W.; Matthews, Brenda C.; Mundy, Lee; Pillai, Thushara; Pound, Marc W.; Stephens, Ian W.; Tobin, John J.; Vaillancourt, John E.; Volgenau, N. H.; Wright, Melvyn C. H.

    2013-01-01

    We present results of lambda 1.3 mm dust-polarization observations toward 16 nearby, low-mass protostars, mapped with similar to 2 ''.5 resolution at CARMA. The results show that magnetic fields in protostellar cores on scales of similar to 1000 AU are not tightly aligned with outflows from the prot

  13. Core TuLiP

    OpenAIRE

    Czenko, M.R.; Etalle, Sandro

    2007-01-01

    We propose CoreTuLiP - the core of a trust management language based on Logic Programming. CoreTuLiP is based on a subset of moded logic programming, but enjoys the features of TM languages such as RT; in particular clauses are issued by different authorities and stored in a distributed manner. We present a lookup and inference algorithm which we prove to be correct and complete w.r.t. the declarative semantics. CoreTuLiP enjoys uniform syntax and the well-established semantics and is express...

  14. Biochemistry Instrumentation Core Technology Center

    Data.gov (United States)

    Federal Laboratory Consortium — The UCLA-DOE Biochemistry Instrumentation Core Facility provides the UCLA biochemistry community with easy access to sophisticated instrumentation for a wide variety...

  15. Powering Earth's dynamo with magnesium precipitation from the core.

    Science.gov (United States)

    O'Rourke, Joseph G; Stevenson, David J

    2016-01-21

    Earth's global magnetic field arises from vigorous convection within the liquid outer core. Palaeomagnetic evidence reveals that the geodynamo has operated for at least 3.4 billion years, which places constraints on Earth's formation and evolution. Available power sources in standard models include compositional convection (driven by the solidifying inner core's expulsion of light elements), thermal convection (from slow cooling), and perhaps heat from the decay of radioactive isotopes. However, recent first-principles calculations and diamond-anvil cell experiments indicate that the thermal conductivity of iron is two or three times larger than typically assumed in these models. This presents a problem: a large increase in the conductive heat flux along the adiabat (due to the higher conductivity of iron) implies that the inner core is young (less than one billion years old), but thermal convection and radiogenic heating alone may not have been able to sustain the geodynamo during earlier epochs. Here we show that the precipitation of magnesium-bearing minerals from the core could have served as an alternative power source. Equilibration at high temperatures in the aftermath of giant impacts allows a small amount of magnesium (one or two weight per cent) to partition into the core while still producing the observed abundances of siderophile elements in the mantle and avoiding an excess of silicon and oxygen in the core. The transport of magnesium as oxide or silicate from the cooling core to underneath the mantle is an order of magnitude more efficient per unit mass as a source of buoyancy than inner-core growth. We therefore conclude that Earth's dynamo would survive throughout geologic time (from at least 3.4 billion years ago to the present) even if core radiogenic heating were minimal and core cooling were slow.

  16. Waves in the core and mechanical core-mantle interactions

    DEFF Research Database (Denmark)

    Jault, D.; Finlay, Chris

    2015-01-01

    the motions in the direction parallel to the Earth'srotation axis. This property accounts for the signicance of the core-mantle topography.In addition, the stiening of the uid in the direction parallel to the rotation axis gives riseto a magnetic diusion layer attached to the core-mantle boundary, which would...

  17. Characterizing the Core via K-Core Covers

    NARCIS (Netherlands)

    Sanchez, S.M.; Borm, P.E.M.; Estevez, A.

    2013-01-01

    This paper extends the notion of individual minimal rights for a transferable utility game (TU-game) to coalitional minimal rights using minimal balanced families of a specific type, thus defining a corresponding minimal rights game. It is shown that the core of a TU-game coincides with the core of

  18. Characterizing the Core via K-Core Covers

    NARCIS (Netherlands)

    Sanchez, S.M.; Borm, P.E.M.; Estevez, A.

    2013-01-01

    This paper extends the notion of individual minimal rights for a transferable utility game (TU-game) to coalitional minimal rights using minimal balanced families of a specific type, thus defining a corresponding minimal rights game. It is shown that the core of a TU-game coincides with the core of

  19. Mass spectrometry

    DEFF Research Database (Denmark)

    Nyvang Hartmeyer, Gitte; Jensen, Anne Kvistholm; Böcher, Sidsel

    2010-01-01

    Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is currently being introduced for the rapid and accurate identification of bacteria. We describe 2 MALDI-TOF MS identification cases - 1 directly on spinal fluid and 1 on grown bacteria. Rapidly obtained r...

  20. Relativistic frozen core potential scheme with relaxation of core electrons

    Science.gov (United States)

    Nakajima, Yuya; Seino, Junji; Hayami, Masao; Nakai, Hiromi

    2016-10-01

    This letter proposes a relaxation scheme for core electrons based on the frozen core potential method at the infinite-order Douglas-Kroll-Hess level, called FCP-CR. The core electrons are self-consistently relaxed using frozen molecular valence potentials after the valence SCF calculation is performed. The efficiency of FCP-CR is confirmed by calculations of gold clusters. Furthermore, FCP-CR reproduces the results of the all-electron method for the energies of coinage metal dimers and the core ionization energies and core level shifts of vinyl acetate and three tungsten complexes at the Hartree-Fock and/or symmetry-adapted cluster configuration interaction levels.

  1. The Early Expansion of Cluster Cores

    CERN Document Server

    Bastian, N; Goodwin, S P; Trancho, G; Smith, L J; Konstantopoulos, I; Efremov, Yu

    2008-01-01

    The observed properties of young star clusters, such as the core radius and luminosity profile, change rapidly during the early evolution of the clusters. Here we present observations of 6 young clusters in M51 where we derive their sizes using HST imaging and ages using deep Gemini-North spectroscopy. We find evidence for a rapid expansion of the cluster cores during the first 20 Myr of their evolution. We confirm this trend by including data from the literature of both Galactic and extra-galactic embedded and young clusters, and possible mechanisms (rapid gas removal, stellar evolutionary mass-loss, and internal dynamical heating) are discussed. We explore the implications of this result, focussing on the fact that clusters were more concentrated in the past, implying that their stellar densities were much higher and relaxation times correspondingly shorter. Thus, when estimating if a particular cluster is dynamically relaxed, (i.e. when determining if a cluster's mass segregation is due to primordial or dy...

  2. Pre-cometary ice composition from hot core chemistry.

    Science.gov (United States)

    Tornow, Carmen; Kührt, Ekkehard; Motschmann, Uwe

    2005-10-01

    Pre-cometary ice located around star-forming regions contains molecules that are pre-biotic compounds or pre-biotic precursors. Molecular line surveys of hot cores provide information on the composition of the ice since it sublimates near these sites. We have combined a hydrostatic hot core model with a complex network of chemical reactions to calculate the time-dependent abundances of molecules, ions, and radicals. The model considers the interaction between the ice and gas phase. It is applied to the Orion hot core where high-mass star formation occurs, and to the solar-mass binary protostar system IRAS 16293-2422. Our calculations show that at the end of the hot core phase both star-forming sites produce the same prebiotic CN-bearing molecules. However, in the Orion hot core these molecules are formed in larger abundances. A comparison of the calculated values with the abundances derived from the observed line data requires a chemically unprocessed molecular cloud as the initial state of hot core evolution. Thus, it appears that these objects are formed at a much younger cloud stage than previously thought. This implies that the ice phase of the young clouds does not contain CN-bearing molecules in large abundances before the hot core has been formed. The pre-biotic molecules synthesized in hot cores cause a chemical enrichment in the gas phase and in the pre-cometary ice. This enrichment is thought to be an important extraterrestrial aspect of the formation of life on Earth and elsewhere.

  3. Adult educators' core competences

    Science.gov (United States)

    Wahlgren, Bjarne

    2016-06-01

    Which competences do professional adult educators need? This research note discusses the topic from a comparative perspective, finding that adult educators' required competences are wide-ranging, heterogeneous and complex. They are subject to context in terms of national and cultural environment as well as the kind of adult education concerned (e.g. basic education, work-related education etc.). However, it seems that it is possible to identify certain competence requirements which transcend national, cultural and functional boundaries. This research note summarises these common or "core" requirements, organising them into four thematic subcategories: (1) communicating subject knowledge; (2) taking students' prior learning into account; (3) supporting a learning environment; and (4) the adult educator's reflection on his or her own performance. At the end of his analysis of different competence profiles, the author notes that adult educators' ability to train adult learners in a way which then enables them to apply and use what they have learned in practice (thus performing knowledge transfer) still seems to be overlooked.

  4. Core of Cloud Computing

    Directory of Open Access Journals (Sweden)

    Prof. C.P.Chandgude

    2017-04-01

    Full Text Available Advancement in computing facilities marks back from 1960’s with introduction of mainframes. Each of the computing has one or the other issues, so keeping this in mind cloud computing was introduced. Cloud computing has its roots in older technologies such as hardware virtualization, distributed computing, internet technologies, and autonomic computing. Cloud computing can be described with two models, one is service model and second is deployment model. While providing several services, cloud management’s primary role is resource provisioning. While there are several such benefits of cloud computing, there are challenges in adopting public clouds because of dependency on infrastructure that is shared by many enterprises. In this paper, we present core knowledge of cloud computing, highlighting its key concepts, deployment models, service models, benefits as well as security issues related to cloud data. The aim of this paper is to provide a better understanding of the cloud computing and to identify important research directions in this field

  5. On the internal dynamics of starless cores: stability of starless cores with internal motions and collapse dynamics

    CERN Document Server

    Seo, Young Min; Shirley, Yancy L

    2013-01-01

    In order to understand the collapse dynamics of observed low-mass starless cores, we revise the conventional stability condition of hydrostatic Bonnor-Ebert spheres to take internal motions into account. Because observed starless cores resemble Bonnor-Ebert density structures, the stability and dynamics of the starless cores are frequently analyzed by comparing to the conventional stability condition of a hydrostatic Bonnor-Ebert sphere. However, starless cores are not hydrostatic but have observed internal motions. In this study, we take gaseous spheres with a homologous internal velocity field and derive stability conditions of the spheres utilizing a virial analysis. We propose two limiting models of spontaneous gravitational collapse: the collapse of critical Bonnor-Ebert spheres and uniform density spheres. The collapse of these two limiting models are intended to provide the lower and the upper limits, respectively, of the infall speeds for a given density structure. The results of our study suggest tha...

  6. The INTEGRAL Core Observing Programme

    OpenAIRE

    Winkler, C; Gehrels, N.; Lund, N.; Schoenfelder, V.; Ubertini, P.

    1999-01-01

    The Core Programme of the INTEGRAL mission is defined as the portion of the scientific programme covering the guaranteed time observations for the INTEGRAL Science Working Team. This paper describes the current status of the Core Programme preparations and summarizes the key elements of the observing programme.

  7. The INTEGRAL Core Observing Programme

    DEFF Research Database (Denmark)

    Winkler, C.; Gehrels, N.; Lund, Niels

    1999-01-01

    The Core Programme of the INTEGRAL mission is defined as the portion of the scientific programme covering the guaranteed time observations for the INTEGRAL Science Working Team. This paper describes the current status of the Core Programme preparations and summarizes the key elements...

  8. Complicated Politics to the Core

    Science.gov (United States)

    McGuinn, Patrick

    2015-01-01

    People dislike the Common Core for several different reasons, and so it is important to disaggregate the sources of opposition and to assess and then to dispel some of the myths that have built up around it. It also is important to understand the unusual political alliances that have emerged in opposition to Common Core implementation and how they…

  9. Common Core: Victory Is Yours!

    Science.gov (United States)

    Fink, Jennifer L. W.

    2012-01-01

    In this article, the author discusses how to implement the Common Core State Standards in the classroom. She presents examples and activities that will leave teachers feeling "rosy" about tackling the new standards. She breaks down important benchmarks and shows how other teachers are doing the Core--and loving it!

  10. The INTEGRAL Core Observing Programme

    DEFF Research Database (Denmark)

    Winkler, C.; Gehrels, N.; Lund, Niels

    1999-01-01

    The Core Programme of the INTEGRAL mission is defined as the portion of the scientific programme covering the guaranteed time observations for the INTEGRAL Science Working Team. This paper describes the current status of the Core Programme preparations and summarizes the key elements...

  11. Complicated Politics to the Core

    Science.gov (United States)

    McGuinn, Patrick

    2015-01-01

    People dislike the Common Core for several different reasons, and so it is important to disaggregate the sources of opposition and to assess and then to dispel some of the myths that have built up around it. It also is important to understand the unusual political alliances that have emerged in opposition to Common Core implementation and how they…

  12. Sloan Great Wall as a complex of superclusters with collapsing cores

    Science.gov (United States)

    Einasto, Maret; Lietzen, Heidi; Gramann, Mirt; Tempel, Elmo; Saar, Enn; Liivamägi, Lauri Juhan; Heinämäki, Pekka; Nurmi, Pasi; Einasto, Jaan

    2016-10-01

    Context. The formation and evolution of the cosmic web is governed by the gravitational attraction of dark matter and antigravity of dark energy (cosmological constant). In the cosmic web, galaxy superclusters or their high-density cores are the largest objects that may collapse at present or during the future evolution. Aims: We study the dynamical state and possible future evolution of galaxy superclusters from the Sloan Great Wall (SGW), the richest galaxy system in the nearby Universe. Methods: We calculated supercluster masses using dynamical masses of galaxy groups and stellar masses of galaxies. We employed normal mixture modelling to study the structure of rich SGW superclusters and search for components (cores) in superclusters. We analysed the radial mass distribution in the high-density cores of superclusters centred approximately at rich clusters and used the spherical collapse model to study their dynamical state. Results: The lower limit of the total mass of the SGW is approximately M = 2.5 × 1016 h-1 M⊙. Different mass estimators of superclusters agree well, the main uncertainties in masses of superclusters come from missing groups and clusters. We detected three high-density cores in the richest SGW supercluster (SCl 027) and two in the second richest supercluster (SCl 019). They have masses of 1.2 - 5.9 × 1015 h-1 M⊙ and sizes of up to ≈60 h-1 Mpc. The high-density cores of superclusters are very elongated, flattened perpendicularly to the line of sight. The comparison of the radial mass distribution in the high-density cores with the predictions of spherical collapse model suggests that their central regions with radii smaller than 8 h-1 Mpc and masses of up to M = 2 × 1015 h-1 M⊙ may be collapsing. Conclusions: The rich SGW superclusters with their high-density cores represent dynamically evolving environments for studies of the properties of galaxies and galaxy systems.

  13. Intermediate-Mass Black Holes

    CERN Document Server

    Miller, M C

    2004-01-01

    The mathematical simplicity of black holes, combined with their links to some of the most energetic events in the universe, means that black holes are key objects for fundamental physics and astrophysics. Until recently, it was generally believed that black holes in nature appear in two broad mass ranges: stellar-mass (roughly 3-20 solar masses), which are produced by the core collapse of massive stars, and supermassive (millions to billions of solar masses), which are found in the centers of galaxies and are produced by a still uncertain combination of processes. In the last few years, however, evidence has accumulated for an intermediate-mass class of black holes, with hundreds to thousands of solar masses. If such objects exist they have important implications for the dynamics of stellar clusters, the formation of supermassive black holes, and the production and detection of gravitational waves. We review the evidence for intermediate-mass black holes and discuss future observational and theoretical work t...

  14. 标准型定位格架对超临界水在堆芯传热和流动影响的数值研究%Numerical research on heat and mass transfer of supercritical water in reactor core with standard grid spacer

    Institute of Scientific and Technical Information of China (English)

    朱晓静; 周盛; 邱庆刚; 沈胜强

    2016-01-01

    Numerical analysis is carried out for the heat and mass transfer ofsupercritical water in the sub-channels with standard grid spacer in supercritical reactor core with commercial software STARCCM+ 6.04 using unstructured polygonal mesh.The results show that the circumferential distribution of cladding temperatureis not uniform due to flow choking effects.The highest value and the lowest value appear at the narrow gap region the sub-channel center respectively.The local heat transferinside the grid spacer strapis greatly enhanceddue to the increased flow velocity.However,the standard grid spacer is negative for decreasing cladding temperature because it increases circumferential difference of cladding temperature in its downstream region and an obvious decreased heat transfer is caused by the aggravated flow choking effects. The decreased heat transfer downstream of a standard grid spacer maybe a unique feature of the tight rod bundle.%采用非结构化多面体网格,利用商业软件 STARCCM+6.04对标准型定位格架对超临界水在反应堆堆芯子通道内流动及传热特性的影响进行了数值研究。研究结果表明,由于流动阻塞效应的影响,燃料棒覆层表面温度周向分布不均,窄缝区最高、中心区最低。标准定位格架能够强化定位格架内部传热,但会造成其下游局部传热弱化,周向温度分布差异增大,不利于降低覆层温度。标准型定位格架下游的传热弱化现象或许是超临界反应堆紧凑型堆芯的特有现象,须在堆芯设计中加以重视。

  15. Effects of magnetic fields on the cosmic-ray ionization of molecular cloud cores

    CERN Document Server

    Padovani, Marco

    2011-01-01

    Low-energy cosmic rays are the dominant source of ionization for molecular cloud cores. The ionization fraction, in turn, controls the coupling of the magnetic field to the gas and hence the dynamical evolution of the cores. The purpose of this work is to compute the attenuation of the cosmic-ray flux rate in a cloud core taking into account magnetic focusing, magnetic mirroring, and all relevant energy loss processes. We adopt a standard cloud model characterized by a mass-to-flux ratio supercritical by a factor of about 2 to describe the density and magnetic field distribution of a low-mass starless core, and we follow the propagation of cosmic rays through the core along flux tubes enclosing different amount of mass. We then extend our analysis to cores with different mass-to-flux ratios. We find that mirroring always dominates over focusing, implying a reduction of the cosmic-ray ionization rate by a factor of about 2-3 over most of a solar-mass core with respect to the value in the intercloud medium outs...

  16. COSIS: COre State Indication System

    Energy Technology Data Exchange (ETDEWEB)

    Cho, J. Y.; Lee, K. B.; Koo, B. S.; Lee, W. K.; Lee, C. C; Zee, S. Q

    2006-02-15

    COSIS (COre State Indication System) which implemented in the SMART research reactor plays a role to supply the core state parameters or graphs for the operator to recognize the core state effectively. The followings are the main functions of COSIS. (1) Validity Check for the Process Signals and Determination of the COSIS Inputs (SIGVAL) (2) Coolant Flow Rate Calculation (FLOW) (3) Core Thermal Power Calculation (COREPOW) (4) In-core 3-Dimensional Power Distribution Calculation and Peaking Parameters Generation (POWER3D) (5) Azimuthal Tilt Calculation (AZITILT). This report describes the methodology of COSIS which produces the core state parameters using the process and detector signals. In the SIGVAL module, COSIS checks most signals except for the CEA position and determines the input signals. In the FLOW module, the corelation coefficient between the RPM signal and coolant flow is updated from the energy balance at the steam generator, and the coolant flow rate is calculated using the RPM signal. In the COREPOW module, the secondary calorimetric power, the primary {delta}T power and the ex-core power are calculated, and the final core thermal power and biased core power are determined. In the POWER3D module, the 3-dimensional power distribution is calculated using the in-core detector signal, and the 3-D peaking factor, 2-D radial peaking factor, axial offset, maximum linear power density are produced. In the AZITILT module, the arithmetic averaged and vector averaged azimuthal tilts are calculated, and the final tilt is determined. The COSIS performance test of the COSIS is performed for the temperature compensation method, the COREPOW and the POWER3D modules. The test for the temperature compensation method is performed for the temperature variations of the linear, parabolic, exponential, sine function. The test shows that the implemented temperature compensation method works soundly. The COREPOW test is performed by varying the core power from the initial

  17. Epistemology and ontology in core ontologies: FOLaw and LRI-Core, two core ontologies for law

    NARCIS (Netherlands)

    Breukers, J.A.P.J.; Hoekstra, R.J.

    2004-01-01

    For more than a decade constructing ontologies for legal domains, we, at the Leibniz Center for Law, felt really the need to develop a core ontology for law that would enable us to re-use the common denominator of the various legal domains. In this paper we present two core ontologies for law. The

  18. Solid charged-core model of ball lightning

    Directory of Open Access Journals (Sweden)

    D. B. Muldrew

    2010-01-01

    Full Text Available In this study, ball lightning (BL is assumed to have a solid, positively-charged core. According to this underlying assumption, the core is surrounded by a thin electron layer with a charge nearly equal in magnitude to that of the core. A vacuum exists between the core and the electron layer containing an intense electromagnetic (EM field which is reflected and guided by the electron layer. The microwave EM field applies a ponderomotive force (radiation pressure to the electrons preventing them from falling into the core. The energetic electrons ionize the air next to the electron layer forming a neutral plasma layer. The electric-field distributions and their associated frequencies in the ball are determined by applying boundary conditions to a differential equation given by Stratton (1941. It is then shown that the electron and plasma layers are sufficiently thick and dense to completely trap and guide the EM field. This model of BL is exceptional in that it can explain all or nearly all of the peculiar characteristics of BL. The ES energy associated with the core charge can be extremely large which can explain the observations that occasionally BL contains enormous energy. The mass of the core prevents the BL from rising like a helium-filled balloon – a problem with most plasma and burning-gas models. The positively charged core keeps the negatively charged electron layer from diffusing away, i.e. it holds the ball together; other models do not have a mechanism to do this. The high electrical charges on the core and in the electron layer explains why some people have been electrocuted by BL. Experiments indicate that BL radiates microwaves upon exploding and this is consistent with the model. The fact that this novel model of BL can explain these and other observations is strong evidence that the model should be taken seriously.

  19. Core Oligosaccharide of Plesiomonas shigelloides PCM 2231 (Serotype O17 Lipopolysaccharide — Structural and Serological Analysis

    Directory of Open Access Journals (Sweden)

    Anna Maciejewska

    2013-02-01

    Full Text Available The herein presented complete structure of the core oligosaccharide of lipopolysaccharide (LPS P. shigelloides Polish Collection of Microorganisms (PCM 2231 (serotype O17 was investigated by 1H, 13C NMR spectroscopy, mass spectrometry, chemical analyses and serological methods. The core oligosaccharide is composed of an undecasaccharide, which represents the second core type identified for P. shigelloides serotype O17 LPS. This structure is similar to that of the core oligosaccharide of P. shigelloides strains 302-73 (serotype O1 and 7-63 (serotype O17 and differs from these only by one sugar residue. Serological screening of 55 strains of P. shigelloides with the use of serum against identified core oligosaccharide conjugated with bovine serum albumin (BSA indicated the presence of similar structures in the LPS core region of 28 O-serotypes. This observation suggests that the core oligosaccharide structure present in strain PCM 2231 could be the most common type among P. shigelloides lipopolysaccharides.

  20. Fermion mass and the pressure of dense matter

    CERN Document Server

    Fraga, Eduardo S; 10.1063/1.2714447

    2008-01-01

    We consider a simple toy model to study the effects of finite fermion masses on the pressure of cold and dense matter, with possible applications in the physics of condensates in the core of neutron stars and color superconductivity.