517 research outputs found
Impact of Judicial Policy in a Local Community: School Desegregation in Oklahoma City
Political Scienc
Monitoring what is real: The effects of modality and action on accuracy and type of reality monitoring error.
Reality monitoring refers to processes involved in distinguishing internally generated information from information presented in the external world, an activity thought to be based, in part, on assessment of activated features such as the amount and type of cognitive operations and perceptual content. Impairment in reality monitoring has been implicated in symptoms of mental illness and associated more widely with the occurrence of anomalous perceptions as well as false memories and beliefs. In the present experiment, the cognitive mechanisms of reality monitoring were probed in healthy individuals using a task that investigated the effects of stimulus modality (auditory vs visual) and the type of action undertaken during encoding (thought vs speech) on subsequent source memory. There was reduced source accuracy for auditory stimuli compared with visual, and when encoding was accompanied by thought as opposed to speech, and a greater rate of externalization than internalization errors that was stable across factors. Interpreted within the source monitoring framework (Johnson, Hashtroudi, & Lindsay, 1993), the results are consistent with the greater prevalence of clinically observed auditory than visual reality discrimination failures. The significance of these findings is discussed in light of theories of hallucinations, delusions and confabulation.JRG was supported by a University of Cambridge Behavioural and Clinical Neuroscience Institute studentship, funded by a joint award from the UK Medical Research Council and the Wellcome Trust. JSS was supported by a James S. McDonnell Foundation Scholar award.This is the final version of the article. It first appeared from Elsevier via https://doi.org/10.1016/j.cortex.2016.06.01
Correlations in the (Sub)Mil1imeter Background from ACT x BLAST
We present measurements of the auto- and cross-frequency correlation power spectra of the cosmic (sub)millimeter background at: 250, 350, and 500 microns (1200, 860, and 600 GHz) from observations made with the Balloon-borne Large Aperture Submillimeter Telescope, BLAST; and at 1380 and 2030 microns (218 and 148 GHz) from observations made with the Atacama Cosmology Telescope, ACT. The overlapping observations cover 8.6 deg(sup 2) in an area relatively free of Galactic dust near the south ecliptic pole (SEP). The ACT bands are sensitive to radiation from the CMB, the Sunyaev-Zel'dovich (SZ) effect from galaxy clusters, and to emission by radio and dusty star-forming galaxies (DSFGs), while the dominant contribution to the BLAST bands is from DSFGs. We confirm and extend the BLAST analysis of clustering with an independent pipeline, and also detect correlations between the ACT and BLAST maps at over 25(sigma) significance, which we interpret as a detection of the DSFGs in the ACT maps. In addition to a Poisson component in the cross-frequency power spectra, we detect a clustered signal at 4(sigma), and using a model for the DSFG evolution and number counts, we successfully fit all our spectra with a linear clustering model and a bias that depends only on red shift and not on scale. Finally, the data are compared to, and generally agree with, phenomenological models for the DSFG population. This study represents a first of its kind, and demonstrates the constraining power of the cross-frequency correlation technique to constrain models for the DSFGs. Similar analyses with more data will impose tight constraints 011 future models
SDSS Standard Star Catalog for Stripe 82: the Dawn of Industrial 1% Optical Photometry
We describe a standard star catalog constructed using multiple SDSS
photometric observations (at least four per band, with a median of ten) in the
system. The catalog includes 1.01 million non-variable unresolved
objects from the equatorial stripe 82 ( 1.266) in
the RA range 20h 34m to 4h 00m, and with the corresponding band
(approximately Johnson V band) magnitudes in the range 14--22. The
distributions of measurements for individual sources demonstrate that the
photometric pipeline correctly estimates random photometric errors, which are
below 0.01 mag for stars brighter than (19.5, 20.5, 20.5, 20, 18.5) in ,
respectively (about twice as good as for individual SDSS runs). Several
independent tests of the internal consistency suggest that the spatial
variation of photometric zeropoints is not larger than 0.01 mag (rms). In
addition to being the largest available dataset with optical photometry
internally consistent at the 1% level, this catalog provides practical
definition of the SDSS photometric system. Using this catalog, we show that
photometric zeropoints for SDSS observing runs can be calibrated within nominal
uncertainty of 2% even for data obtained through 1 mag thick clouds, and
demonstrate the existence of He and H white dwarf sequences using photometric
data alone. Based on the properties of this catalog, we conclude that upcoming
large-scale optical surveys such as the Large Synoptic Survey Telescope will be
capable of delivering robust 1% photometry for billions of sources.Comment: 63 pages, 24 figures, submitted to AJ, version with correct figures
and catalog available from
http://www.astro.washington.edu/ivezic/sdss/catalogs/stripe82.htm
Measuring the matter density using baryon oscillations in the SDSS
We measure the cosmological matter density by observing the positions of
baryon acoustic oscillations in the clustering of galaxies in the Sloan Digital
Sky Survey (SDSS). We jointly analyse the main galaxies and LRGs in the SDSS
DR5 sample, using over half a million galaxies in total. The oscillations are
detected with 99.74% confidence (3.0sigma assuming Gaussianity) compared to a
smooth power spectrum. When combined with the observed scale of the peaks
within the CMB, we find a best-fit value of Omega_m=0.256+0.029-0.024 (68%
confidence interval), for a flat Lambda cosmology when marginalising over the
Hubble parameter and the baryon density. This value of the matter density is
derived from the locations of the baryon oscillations in the galaxy power
spectrum and in the CMB, and does not include any information from the overall
shape of the power spectra. This is an extremely clean cosmological measurement
as the physics of the baryon acoustic oscillation production is well
understood, and the positions of the oscillations are expected to be
independent of systematics such as galaxy bias.Comment: 5 pages, 3 figures, updated to match version accepted by Ap
Evidence for dark energy from the cosmic microwave background alone using the Atacama Cosmology Telescope lensing measurements
For the first time, measurements of the cosmic microwave background radiation
(CMB) alone favor cosmologies with dark energy over models without dark
energy at a 3.2-sigma level. We demonstrate this by combining the CMB lensing
deflection power spectrum from the Atacama Cosmology Telescope with temperature
and polarization power spectra from the Wilkinson Microwave Anisotropy Probe.
The lensing data break the geometric degeneracy of different cosmological
models with similar CMB temperature power spectra. Our CMB-only measurement of
the dark energy density confirms other measurements from
supernovae, galaxy clusters and baryon acoustic oscillations, and demonstrates
the power of CMB lensing as a new cosmological tool.Comment: 4 pages, 3 figures; replaced with version accepted by Physical Review
Letters, added sentence on models with non-standard primordial power spectr
- …