1,676 research outputs found

    The Solar Neighborhood XV: Discovery of New High Proper Motion Stars with mu >= 0.4"/yr between Declinations -47 degrees and 00 degrees

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    We report the discovery of 152 new high proper motion systems (mu >= 0.4"/yr) in the southern sky (Declination = -47 degrees to 00 degrees) brighter than UKST plate R_{59F} =16.5 via our SuperCOSMOS-RECONS (SCR) search. This paper complements Paper XII in The Solar Neighborhood series, which covered the region from Declination = -90 degrees to -47 degrees and discussed all 147 new systems from the southernmost phase of the search. Among the total of 299 systems from both papers, there are 148 (71 in Paper XII, 77 in this paper) new systems moving faster than 0.5"/yr that are additions to the classic ``LHS'' (Luyten Half Second) sample. These constitute an 8% increase in the sample of all stellar systems with mu >= 0.5"/yr in the southern sky. As in Paper XII, distance estimates are provided for the systems reported here based upon a combination of photographic plate magnitudes and 2MASS photometry, assuming all stars are on the main sequence. Two SCR systems from the portion of the sky included in this paper are anticipated to be within 10 pc, and an additional 23 are within 25 pc. In total, the results presented in Paper XII and here for this SCR sweep of the entire southern sky include five new systems within 10 pc and 38 more between 10 and 25 pc. The largest number of nearby systems have been found in the slowest proper motion bin, 0.6"/yr > mu >= 0.4"/yr, indicating that there may be a large population of low proper motion systems very near the Sun.Comment: 36 pages, 5 figures, accepted for publication in Astronomical Journa

    A model of phytoplankton plume formation during variable Oregon upwelling

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    A time dependent, two-dimensional, marine ecosystem model relates wind events, upwelling, and primary production off the Oregon coast. Model predictions of daily primary production (mg N m-2 day-1) increase soon after an intensification of the northerly component of the wind stress. Paradoxically the highest phytoplankton concentration occurs upon relaxation of winds after a major upwelling event...

    Robustness of baryon-strangeness correlation and related ratios of susceptibilities

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    Using quenched lattice QCD simulations we investigate the continuum limit of baryon-strangeness correlation and other related conserved charge-flavour correlations for temperatures T_c<T\le2T_c. By working with lattices having large temporal extents (N_\tau=12, 10, 8, 4) we find that these quantities are almost independent of the lattice spacing, i.e, robust. We also find that these quantities have very mild dependence on the sea quark mass and acquire values which are very close to their respective ideal gas limits. Our results also confirm robustness of the Wroblewski parameter.Comment: Published versio

    Bank Markazi v. Peterson: Threatening the Separation of Powers Doctrine

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    The Nearshore Fish Fauna of Bonne Bay, a Fjord within Gros Morne National Park, Newfoundland

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    A standardized survey of the nearshore fish fauna of Bonne Bay, a fjord within Gros Morne National Park in western Newfoundland, was conducted using beach seines, gill-nets and bottom trawls during the month of June over a seven year period (2002- 2008). The survey documents the presence of 31 fish species (in 17 taxonomic families). Sampling sites varied in benthic habitat and associated fish assemblages. Both juvenile and adult life history stages of Atlantic cod (Gadus morhua) were present in Bonne Bay, suggesting the presence of a local population or “bay cod stock”. Acadian redfish (Sebastes fasciatus) live in the bay, and may be members of a genetically differentiable population of redfish. Striped wolfish (Anarhichas lupus), a fish species protected under Canada’s Species at Risk Act (SARA), inhabits Bonne Bay. Surrounded by Gros Morne National Park, this bay with a diverse fish fauna is a focus of local stewardship and conservation efforts

    The Solar Neighborhood XII: Discovery of New High Proper Motion Stars with 1.0"/yr > mu >= 0.4"/yr between Declinations -90 degrees and -47 degrees

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    We report the discovery of 141 new high proper motion systems (1.0"/yr > mu >= 0.4"/yr) in the southern sky (Declination = -90 degrees to -47 degrees) brighter than UKST plate R_{59F} = 16.5 via our SuperCOSMOS-RECONS (SCR) search. When combined with the nine systems having mu >= 1.0"/yr and/or late spectral type from the initial phases of this effort (Hambly et al. 2004, Henry et al. 2004), we find that 73 of the 150 total systems are moving faster than 0.5"/yr, and are therefore new members of the classic "LHS" (Luyten Half Second) sample. These constitute a 21% increase in the sample of stars with mu >= 0.5"/yr in the declination region searched, thereby comprising an important addition to this long-neglected region of the sky. Distance estimates are provided for the entire sample, based upon a combination of photographic plate magnitudes and 2MASS photometry, using the relations presented in Hambly et al. (2004) for the presumed main sequence stars. Three systems are anticipated to be within 10 pc, and an additional 15 are within 25 pc. Eight of these 18 nearby systems have proper motions falling between 0.4"/yr and 0.6"/yr, hinting at a large population of nearby stars with fast, but not extremely high, proper motions that have not been thoroughly investigated.Comment: 45 pages, 6 figures, accepted for publication in Astronomical Journal (January 2005

    Status of Chemical Equilibrium in Relativistic Heavy Ion Collisions

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    Recent work on chemical equilibrium in heavy ion collisions is reviewed. The energy dependence of thermal parameters is discussed. The centrality dependence of thermal parameters at SPS energies is presented.Comment: 7 pages, 7 Postscript figure

    Factors Associated with the Diversification of the Gut Microbial Communities within Chimpanzees from Gombe National Park.

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    The gastrointestinal tract harbors large and diverse populations of bacteria that vary among individuals and within individuals over time. Numerous internal and external factors can influence the contents of these microbial communities, including diet, geography, physiology, and the extent of contact among hosts. To investigate the contributions of such factors to the variation and changes in gut microbial communities, we analyzed the distal gut microbiota of individual chimpanzees from two communities in Gombe National Park, Tanzania. These samples, which were derived from 35 chimpanzees, many of whom have been monitored for multiple years, provide an unusually comprehensive longitudinal depth for individuals of known genetic relationships. Although the composition of the great-ape microbiota has been shown to codiversify with host species, indicating that host genetics and phylogeny have played a major role in its differentiation over evolutionary timescales, the geneaological relationships of individual chimpanzees did not coincide with the similarity in their gut microbial communities. However, the inhabitants from adjacent chimpanzee communities could be distinguished based on the contents of their gut microbiota. Despite the broad similarity of community members, as would be expected from shared diet or interactions, long-term immigrants to a community often harbored the most distinctive gut microbiota, suggesting that individuals retain hallmarks of their previous gut microbial communities for extended periods. This pattern was reinforced in several chimpanzees sampled over long temporal scales, in which the major constituents of the gut microbiota were maintained for nearly a decade

    Transition from Baryon- to Meson-Dominated Freeze Out -- Early Decoupling around 30 A GeV?

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    The recently discovered sharp peak in the excitation function of the K+/pi+ ratio around 30 A GeV in relativistic heavy-ion collisions is discussed in the framework of the Statistical Model. In this model, the freeze-out of an ideal hadron gas changes from a situation where baryons dominate to one with mainly mesons. This transition occurs at a temperature T = 140 MeV and baryon chemical potential mu(B) = 410 MeV corresponding to an energy of sqrt(s) = 8.2 GeV. The calculated maximum in the K+/pi+ ratio is, however, much less pronounced than the one observed by the NA49 Collaboration. The smooth increase of the K-/pi- ratio with incident energy and the shape of the excitation functions of the Lambda/pi+, Xi-/pi+ and Omega/pi ratios all exhibiting maxima at different incident energies, is consistent with the presently available experimental data. The measured K+/pi+ ratio exceeds the calculated one just at the incident energy when the freeze-out condition is changing. We speculate that at this point freeze-out might occur in a modified way. We discuss a scenario of an early freeze-out which indeed increases K+/pi+ ratio while most other particle ratios remain essentially unchanged. Such an early freeze-out is supported by results from HBT studies.Comment: 8 pages, 5 figures, SQM2006 conference, Los Angeles, March 200

    Application of Stereo PIV on a Supersonic Parachute Model

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    The Mars Science Laboratory (MSL) is the next step in NASA's Mars Exploration Program, currently scheduled for 2011. The spacecraft's descent into the Martian atmosphere will be slowed from Mach 2 to subsonic speeds via a large parachute system with final landing under propulsive control. A Disk-Band-Gap (DBG) parachute will be used on MSL similar to the designs that have been used on previous missions, however; the DBG parachute used by MSL will be larger (21.5 m) than in any of the previous missions due to the weight of the payload and landing site requirements. The MSL parachute will also deploy at higher Mach number (M 2) than previous parachutes, which can lead to instabilities in canopy performance. Both the increased size of the DBG above previous demonstrated configurations and deployment at higher Mach numbers add uncertainty to the deployment, structural integrity and performance of the parachute. In order to verify the performance of the DBG on MSL, experimental testing, including acquisition of Stereo Particle Imaging Velocimetry (PIV) measurements were required for validating CFD predictions of the parachute performance. A rigid model of the DBG parachute was tested in the 10x10 foot wind tunnel at GRC. Prior to the MSL tests, a PIV system had never been used in the 10x10 wind tunnel. In this paper we discuss some of the technical challenges overcome in implementing a Stereo PIV system with a 750x400 mm field-of-view in the 10x10 wind tunnel facility and results from the MSL hardshell canopy tests
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