792 research outputs found
Preprocessing Among the Infalling Galaxy Population of EDisCS Clusters
We present results from a low-resolution spectroscopic survey for 21 galaxy
clusters at selected from the ESO Distant Cluster Survey. We
measured spectra using the low-dispersion prism in IMACS on the Magellan Baade
telescope and calculate redshifts with an accuracy of . We
find 1763 galaxies that are brighter than in the large-scale cluster
environs. We identify the galaxies expected to be accreted by the clusters as
they evolve to using spherical infall models and find that
to of the cluster population lies outside the virial radius
at . For analogous clusters at , we calculate that the ratio
of galaxies that have fallen into the clusters since to those that
were already in the core at that redshift is typically between and
. This wide range of ratios is due to intrinsic scatter and is not a
function of velocity dispersion, so a variety of infall histories is to be
expected for clusters with current velocity dispersions of km s. Within the infall regions of clusters, we find a larger red fraction of galaxies than in the field and
greater clustering among red galaxies than blue. We interpret these findings as
evidence of "preprocessing", where galaxies in denser local environments have
their star formation rates affected prior to their aggregation into massive
clusters, although the possibility of backsplash galaxies complicates the
interpretation.Comment: Accepted for publication in Ap
Neuropathological background of phenotypical variability in frontotemporal dementia
Frontotemporal lobar degeneration (FTLD) is the umbrella term encompassing a heterogeneous group of pathological disorders. With recent discoveries, the FTLDs have been show to classify nicely into three main groups based on the major protein deposited in the brain: FTLD-tau, FTLD-TDP and FTLD-FUS. These pathological groups, and their specific pathologies, underlie a number of well-defined clinical syndromes, including three frontotemporal dementia (FTD) variants [behavioral variant frontotemporal dementia (bvFTD), progressive non-fluent aphasia, and semantic dementia (SD)], progressive supranuclear palsy syndrome (PSPS) and corticobasal syndrome (CBS). Understanding the neuropathological background of the phenotypic variability in FTD, PSPS and CBS requires large clinicopathological studies. We review current knowledge on the relationship between the FTLD pathologies and clinical syndromes, and pool data from a number of large clinicopathological studies that collectively provide data on 544 cases. Strong relationships were identified as follows: FTD with motor neuron disease and FTLD-TDP; SD and FTLD-TDP; PSPS and FTLD-tau; and CBS and FTLD-tau. However, the relationship between some of these clinical diagnoses and specific pathologies is not so clear cut. In addition, the clinical diagnosis of bvFTD does not have a strong relationship to any FTLD subtype or specific pathology and therefore remains a diagnostic challenge. Some evidence suggests improved clinicopathological association of bvFTD by further refining clinical characteristics. Unlike FTLD-tau and FTLD-TDP, FTLD-FUS has been less well characterized, with only 69 cases reported. However, there appears to be some associations between clinical phenotypes and FTLD-FUS pathologies. Clinical diagnosis is therefore promising in predicting molecular pathology
Revised Stellar Properties of Kepler Targets for the Quarter 1-16 Transit Detection Run
We present revised properties for 196,468 stars observed by the NASA Kepler
Mission and used in the analysis of Quarter 1-16 (Q1-Q16) data to detect and
characterize transiting exoplanets. The catalog is based on a compilation of
literature values for atmospheric properties (temperature, surface gravity, and
metallicity) derived from different observational techniques (photometry,
spectroscopy, asteroseismology, and exoplanet transits), which were then
homogeneously fitted to a grid of Dartmouth stellar isochrones. We use
broadband photometry and asteroseismology to characterize 11,532 Kepler targets
which were previously unclassified in the Kepler Input Catalog (KIC). We report
the detection of oscillations in 2,762 of these targets, classifying them as
giant stars and increasing the number of known oscillating giant stars observed
by Kepler by ~20% to a total of ~15,500 stars. Typical uncertainties in derived
radii and masses are ~40% and ~20%, respectively, for stars with photometric
constraints only, and 5-15% and ~10% for stars based on spectroscopy and/or
asteroseismology, although these uncertainties vary strongly with spectral type
and luminosity class. A comparison with the Q1-Q12 catalog shows a systematic
decrease in radii for M dwarfs, while radii for K dwarfs decrease or increase
depending on the Q1-Q12 provenance (KIC or Yonsei-Yale isochrones). Radii of
F-G dwarfs are on average unchanged, with the exception of newly identified
giants. The Q1-Q16 star properties catalog is a first step towards an improved
characterization of all Kepler targets to support planet occurrence studies.Comment: 20 pages, 14 figures, 5 tables; accepted for publication in ApJS;
electronic versions of Tables 4 and 5 are available as ancillary files (see
sidebar on the right), and an interactive version of Table 5 is available at
the NASA Exoplanet Archive (http://exoplanetarchive.ipac.caltech.edu/
The Revised TESS Input Catalog and Candidate Target List
We describe the catalogs assembled and the algorithms used to populate the
revised TESS Input Catalog (TIC), based on the incorporation of the Gaia second
data release. We also describe a revised ranking system for prioritizing stars
for 2-minute cadence observations, and assemble a revised Candidate Target List
(CTL) using that ranking. The TIC is available on the Mikulski Archive for
Space Telescopes (MAST) server, and an enhanced CTL is available through the
Filtergraph data visualization portal system at the URL
http://filtergraph.vanderbilt.edu/tess_ctl.Comment: 30 pages, 16 figures, submitted to AAS Journals; provided to the
community in advance of publication in conjunction with public release of the
TIC/CTL on 28 May 201
Use of traditional knowledge by the United States Bureau of Ocean Energy Management to support resource management
Professionals who collect and use traditional knowledge to support resource management decisions often are preoccupied with concerns over how and if traditional knowledge should be integrated with science. To move beyond the integration dilemma, we treat traditional knowledge and science as distinct and complementary knowledge systems. We focus on applying traditional knowledge within the decision-making process. We present succinct examples of how the Bureau of Ocean Energy Management has used traditional knowledge in decision making in the North Slope Borough, Alaska: 1) using traditional knowledge in designing, planning, and conducting scientific research; 2) applying information from both knowledge systems at the earliest opportunity in the process; 3) using traditional knowledge in environmental impacts assessment; 4) consulting with indigenous leaders at key decision points; and 5) applying traditional knowledge at a programmatic decision level. Clearly articulating, early in the process, how best to use traditional knowledge and science can allow for more complete and inclusive use of available and pertinent information
Recent Advances in Understanding Particle Acceleration Processes in Solar Flares
We review basic theoretical concepts in particle acceleration, with
particular emphasis on processes likely to occur in regions of magnetic
reconnection. Several new developments are discussed, including detailed
studies of reconnection in three-dimensional magnetic field configurations
(e.g., current sheets, collapsing traps, separatrix regions) and stochastic
acceleration in a turbulent environment. Fluid, test-particle, and
particle-in-cell approaches are used and results compared. While these studies
show considerable promise in accounting for the various observational
manifestations of solar flares, they are limited by a number of factors, mostly
relating to available computational power. Not the least of these issues is the
need to explicitly incorporate the electrodynamic feedback of the accelerated
particles themselves on the environment in which they are accelerated. A brief
prognosis for future advancement is offered.Comment: This is a chapter in a monograph on the physics of solar flares,
inspired by RHESSI observations. The individual articles are to appear in
Space Science Reviews (2011
Search for medium modification of the meson
The photoproduction of vector mesons on various nuclei has been studied using
the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Laboratory. The
vector mesons, , , and , are observed via their decay to
, in order to reduce the effects of final state interactions in the
nucleus. Of particular interest are possible in-medium effects on the
properties of the meson. The spectral function is extracted from
the data on various nuclei, carbon, iron, and titanium, and compared to the
spectrum from liquid deuterium, which is relatively free of nuclear effects. We
observe no significant mass shift for the meson; however, there is some
widening of the resonance in titanium and iron, which is consistent with
expected collisional broadening.Comment: 8 pages, 4 figure
Standalone vertex ďŹnding in the ATLAS muon spectrometer
A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at âs = 7 TeV collected with the ATLAS detector at the LHC during 2011
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