8,008 research outputs found
HeCS-SZ: The Hectospec Survey of Sunyaev-Zeldovich Selected Clusters
We estimate cluster masses and velocity dispersions for 123 clusters from
optical spectroscopy to compare the Sunyaev-Zeldovich (SZ) mass proxy and
dynamical masses. Our new survey, HeCS-SZ (Hectospec Cluster Survey of
SZ-selected clusters), includes 7,721 new or remeasured redshifts from
MMT/Hectospec observations of 24 SZ-selected clusters at redshifts
=0.05-0.20 and not in previous surveys. We supplement the Hectospec data
with spectra from the Sloan Digital Sky Survey (SDSS) and cluster data from the
Cluster Infall Regions in SDSS (CIRS) project and the Hectospec Cluster Survey
(HeCS), our Hectospec survey of clusters selected by X-ray flux. We measure the
scaling relation between velocity dispersion and SZ mass estimates from the
integrated Compton parameter for an SZ complete sample of 83 clusters. The
observed relation agrees very well with a simple virial scaling from mass
(based on SZ) to velocity dispersion. The SZ mass estimates (calibrated with
hydrostatic X-ray mass estimates) are not significantly biased. Further, the
velocity dispersion of cluster galaxies is consistent with the expected
velocity dispersion of dark matter particles, indicating that galaxies are good
dynamical tracers (i.e., velocity bias is small). Significant mass bias in SZ
mass estimates could relieve tension between cosmological results from Planck
SZ cluster counts and Planck CMB data. However, the excellent agreement between
our measured velocity dispersions and those predicted from a virial scaling
relation suggests that any SZ mass bias is too small to reconcile SZ and CMB
results. In principle, SZ mass bias and velocity bias of galaxies could
conspire to yield good agreement, but the required velocity bias is
, outside the range of plausible models
of velocity bias in the literature.Comment: submitted to ApJ, 13 pages, 14 figures, 123 cluster
A WISE View of a Nearby Supercluster A2199
We use Wide-field Infrared Survey Explorer (WISE) data covering the entire
region (~130 deg^2) of the A2199 supercluster at z=0.03 to study the
mid-infrared (MIR) properties of supercluster galaxies. We identify a `MIR
star-forming sequence' in the WISE [3.4]-[12] color-12 \mu m luminosity
diagram, consisting of late-type, star-forming galaxies. At a fixed star
formation rate (SFR), the MIR-detected galaxies at 22 \mu m or 12 \mu m tend to
be more metal rich and to have higher surface brightness than those without MIR
detection. Using these MIR-detected galaxies, we construct the IR luminosity
function (LF) and investigate its environmental dependence. Both total IR (TIR)
and 12 \mu m LFs are dominated by late-type, star-forming galaxies. The
contribution of active galactic nuclei (AGN)-host galaxies increases with both
TIR and 12 \mu m luminosities. The contribution of early-type galaxies to the
12 \mu m LFs increases with decreasing luminosity. The faint-end slope of the
TIR LFs does not change with environment, but the change of faint-end slope in
the 12 \mu m LFs with the environment is significant: there is a steeper
faint-end slope in the cluster core than in the cluster outskirts. This
steepening results primarily from the increasing contribution of early-type
galaxies toward the cluster. These galaxies are passively evolving, and contain
old stellar populations with weak MIR emission from the circumstellar dust
around asymptotic giant branch stars.Comment: 14 pages, 14 figures. To appear in Ap
Concurrent investigation of global motion and form processing in amblyopia: an equivalent noise approach
PURPOSE: Directly comparing the motion and form processing in neurologic disorders has remained difficult due to the limitations in the experimental stimulus. In the current study, motion and form processing in amblyopia was characterized using random dot stimuli in different noise levels to parse out the effect of local and global processing on motion and form perception. METHODS: A total of 17 amblyopes (8 anisometropic and 9 strabismic), and 12 visually normal subjects monocularly estimated the global direction of motion and global orientation in random dot kinematograms (RDK) and Glass patterns (Glass), whose directions/orientations were drawn from normal distributions with a range of means and variances that served as external noise. Direction/orientation discrimination thresholds were measured without noise first then variance threshold was measured at the multiples of the direction/orientation threshold. The direction/orientation and variance thresholds were modelled to estimate internal noise and sampling efficiency parameters. RESULTS: Overall, the thresholds for Glass were higher than RDK for all subjects. The thresholds for both Glass and RDK were higher in the strabismic eyes compared with the fellow and normal eyes. On the other hand, the thresholds for anisometropic amblyopic eyes were similar to the normal eyes. The worse performance of strabismic amblyopes was best explained by relatively low sampling efficiency compared with other groups (P < 0.05). CONCLUSIONS: A deficit in global motion and form perception was only evident in strabismic amblyopia. Contrary to the dorsal stream deficiency hypothesis assumed in other developmental disorders, deficits were present in both motion (dorsal) and form (ventral) processing
Herd Behaviors in Financial Markets
We investigate the herd behavior of returns for the yen-dollar exchange rate
in the Japanese financial market. It is obtained that the probability
distribution of returns satisfies the power-law behavior with the exponents (the time interval
one minute) and 3.36( one day). The informational cascade regime appears
in the herding parameter at one minute, while it occurs no
herding at one day. Especially, we find that the distribution of
normalized returns shows a crossover to a Gaussian distribution at one time
step day.Comment: 15 pages, 6 figure
An Economic Performance Analysis of the Beef Cow-herd Enterprise Using a Stochastic Frontier Function
Standardized Performance Analysis (SPA) data from Texas, Oklahoma, and New Mexico were used to examine the economic performance of beef cow herd operations in the Southern Plains region by measuring their technical efficiency index. Factors that make significant impacts on the production are herd size, machinery investment per breeding cow, and rainfall. Little technical inefficiency among the Southern beef cattle operations that participated in the SPA data was found.beef, cattle, cost, cow-calf, production, stochastic production function., Farm Management, Livestock Production/Industries, Production Economics,
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