2,316 research outputs found
The N2-P3 complex of the evoked potential and human performance
The N2-P3 complex and other endogenous components of human evoked potential provide a set of tools for the investigation of human perceptual and cognitive processes. These multidimensional measures of central nervous system bioelectrical activity respond to a variety of environmental and internal factors which have been experimentally characterized. Their application to the analysis of human performance in naturalistic task environments is just beginning. Converging evidence suggests that the N2-P3 complex reflects processes of stimulus evaluation, perceptual resource allocation, and decision making that proceed in parallel, rather than in series, with response generation. Utilization of these EP components may provide insights into the central nervous system mechanisms modulating task performance unavailable from behavioral measures alone. The sensitivity of the N2-P3 complex to neuropathology, psychopathology, and pharmacological manipulation suggests that these components might provide sensitive markers for the effects of environmental stressors on the human central nervous system
Attention, effort, and fatigue: Neuropsychological perspectives
Models of attention, effort, and fatigue are reviewed. Methods are discussed for measuring these phenomena from a neuropsychological and psychophysiological perspective. The following methodologies are included: (1) the autonomic measurement of cognitive effort and quality of encoding; (2) serial assessment approaches to neurophysiological assessment; and (3) the assessment of subjective reports of fatigue using multidimensional ratings and their relationship to neurobehavioral measures
Individual Insurance: Health Insurers Try to Tap Potential Market Growth
Examines the challenges the current individual health insurance market poses for insurers and consumers, the market's growth potential, market and regulatory conditions across states, and trends in marketing strategies. Considers policy implications
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ECRG4 regulates neutrophil recruitment and CD44 expression during the inflammatory response to injury.
The complex molecular microenvironment of the wound bed regulates the duration and degree of inflammation in the wound repair process, while its dysregulation leads to impaired healing. Understanding factors controlling this response provides therapeutic targets for inflammatory disease. Esophageal cancer-related gene 4 (ECRG4) is a candidate chemokine that is highly expressed on leukocytes. We used ECRG4 knockout (KO) mice to establish that the absence of ECRG4 leads to defective neutrophil recruitment with a delay in wound healing. An in vitro human promyelocyte model identified an ECRG4-mediated suppression of the hyaluronic acid receptor, CD44, a key receptor mediating inflammation resolution. In ECRG4 KO mouse leukocytes, there was an increase in CD44 expression, consistent with a model in which ECRG4 negatively regulates CD44 levels. Therefore, we propose a previously unidentified mechanism in which ECRG4 regulates early neutrophil recruitment and subsequent CD44-mediated resolution of inflammation
The Economic Recession: Early Impacts on Health Care Safety Net Providers
Examines how the recession and state and local budget cuts affected safety-net clinics' capacity to meet demand in five communities, the extent to which federal stimulus funds mitigated the impact, strategies for sustainability, and implications
Infrared point source variability between the Spitzer and MSX surveys of the Galactic mid-plane
We present a list of 552 sources with suspected variability, based on a
comparison of mid-infrared photometry from the GLIMPSE I and MSX surveys, which
were carried out nearly a decade apart. We were careful to address issues such
as the difference in resolution and sensitivity between the two surveys, as
well as the differences in the spectral responses of the instruments. We
selected only sources where the IRAC 8.0 and MSX 8.28 micron fluxes differ by
more than a factor of two, in order to minimize contamination from sources
where the difference in fluxes at 8 micron is due to a strong 10 micron
silicate feature. We present a subset of 40 sources for which additional
evidence suggests variability, using 2MASS and MIPSGAL data. Based on a
comparison with the variability flags in the IRAS and MSX Point-Source Catalogs
we estimate that at least a quarter of the 552 sources, and at least half of
the 40 sources are truly variable. In addition, we tentatively confirm the
variability of one source using multi-epoch IRAS LRS spectra. We suggest that
most of the sources in our list are likely to be Asymptotic Giant Branch stars.Comment: 47 pages, 12 Figures, 3 Tables, accepted for publication in A
Absolute diffuse calibration of IRAC through mid-infrared and radio study of HII regions
We investigate the diffuse absolute calibration of the InfraRed Array Camera
on the Spitzer Space Telescope at 8.0microns using a sample of 43 HII regions
with a wide range of morphologies near GLON=312deg. For each region we
carefully measure sky-subtracted,point-source- subtracted, areally-integrated
IRAC 8.0-micron fluxes and compare these with Midcourse Space eXperiment (MSX)
8.3-micron images at two different spatial resolutions, and with radio
continuum maps. We determine an accurate median ratio of IRAC
8.0-micron/MSX\8.3-micron fluxes, of 1.55+/-0.15. From robust spectral energy
distributions of these regions we conclude that the present 8.0-micron diffuse
calibration of the SST is 36% too high compared with the MSX validated
calibration, perhaps due to scattered light inside the camera. This is an
independent confirmation of the result derived for the diffuse calibration of
IRAC by the Spitzer Science Center (SSC).
From regression analyses we find that 843-MHz radio fluxes of HII regions and
mid-infrared (MIR) fluxes are linearly related for MSX at 8.3-microns and
Spitzer at 8.0 microns, confirming the earlier MSX result by Cohen & Green. The
median ratio of MIR/843-MHz diffuse continuum fluxes is 600 times smaller in
nonthermal than thermal regions, making it a sharp discriminant. The ratios are
largely independent of morphology up to a size of ~24 arcsec. We provide
homogeneous radio and MIR morphologies for all sources. MIR morphology is not
uniquely related to radio structure. Compact regions may have MIR filaments
and/or diffuse haloes, perhaps infrared counter- parts to weakly ionized radio
haloes found around compact HII regions. We offer two IRAC colour-colour plots
as quantitative diagnostics of diffuse HII regions.Comment: 29 pages, LaTeX (aastex), incl. 31 PostScript (ps,eps) figures and 5
tables. Accepted by MNRAS (main journal). Replaced an unused file and added
this URL for people wishing to download a version with high-resolution
images: http://www.astro.wisc.edu/sirtf/martin.hii.accepted.pd
Automated Determination of [Fe/H] and [C/Fe] from Low-Resolution Spectroscopy
We develop an automated spectral synthesis technique for the estimation of
metallicities ([Fe/H]) and carbon abundances ([C/Fe]) for metal-poor stars,
including carbon-enhanced metal-poor stars, for which other methods may prove
insufficient. This technique, autoMOOG, is designed to operate on relatively
strong features visible in even low- to medium-resolution spectra, yielding
results comparable to much more telescope-intensive high-resolution studies. We
validate this method by comparison with 913 stars which have existing
high-resolution and low- to medium-resolution to medium-resolution spectra, and
that cover a wide range of stellar parameters. We find that at low
metallicities ([Fe/H] < -2.0), we successfully recover both the metallicity and
carbon abundance, where possible, with an accuracy of ~ 0.20 dex. At higher
metallicities, due to issues of continuum placement in spectral normalization
done prior to the running of autoMOOG, a general underestimate of the overall
metallicity of a star is seen, although the carbon abundance is still
successfully recovered. As a result, this method is only recommended for use on
samples of stars of known sufficiently low metallicity. For these
low-metallicity stars, however, autoMOOG performs much more consistently and
quickly than similar, existing techniques, which should allow for analyses of
large samples of metal-poor stars in the near future. Steps to improve and
correct the continuum placement difficulties are being pursued.Comment: 8 pages, 7 figures; accepted for publication in A
Dynamically Warped Theory Space and Collective Supersymmetry Breaking
We study deconstructed gauge theories in which a warp factor emerges
dynamically and naturally. We present nonsupersymmetric models in which the
potential for the link fields has translational invariance, broken only by
boundary effects that trigger an exponential profile of vacuum expectation
values. The spectrum of physical states deviates exponentially from that of the
continuum for large masses; we discuss the effects of such exponential towers
on gauge coupling unification. We also present a supersymmetric example in
which a warp factor is driven by Fayet-Iliopoulos terms. The model is peculiar
in that it possesses a global supersymmetry that remains unbroken despite
nonvanishing D-terms. Inclusion of gravity and/or additional messenger fields
leads to the collective breaking of supersymmetry and to unusual phenomenology.Comment: 28 pages LaTeX, JHEP format, 7 eps figures (v2: reference added
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