6,952 research outputs found
Functional imaging reveals working memory and attention interact to produce the attentional blink
Copyright @ 2012 Massachusetts Institute of Technology PressIf two centrally presented visual stimuli occur within approximately half a second of each other, the second target often fails to be reported correctly. This effect, called the attentional blink (AB; Raymond, J. E., Shapiro, K. L., & Arnell, K. M. Temporary suppression of visual processing in an RSVP task: An attentional blink? Journal of Experimental Psychology, Human Perception and Performance, 18, 849-860, 1992], has been attributed to a resource "bottleneck," likely arising as a failure of attention during encoding into or retrieval from visual working memory (WM). Here we present participants with a hybrid WM-AB study while they undergo fMRI to provide insight into the neural underpinnings of this bottleneck. Consistent with a WM-based bottleneck account, fronto-parietal brain areas exhibited a WM load-dependent modulation of neural responses during the AB task. These results are consistent with the view that WM and attention share a capacity-limited resource and provide insight into the neural structures that underlie resource allocation in tasks requiring joint use of WM and attention.This research was supported by a project grant (071944) from the Wellcome Trust to Kimron Shapiro
Itâs the way he tells them (and who is listening):menâs dominance is positively correlated with their preference for jokes told by dominant-sounding men
While much research has explored humorous exchange in relation to mate choice, recent perspectives have emphasized the importance of humor for monitoring interest within social partnerships more generally. Indeed, given that similarity is thought to be important in the maintenance of social partnerships, we may expect humor appreciation to vary according to the degree of similarity between humor producers and recipients. In the current study we report evidence for such variation that is specific to menâs judgments of other menâs humor. Here we manipulated voice pitch in a set of âone-linerâ jokes to create low-pitched and high-pitched versions of men and women telling jokes. A composite measure of menâs own dominance was positively correlated with their preference for jokes told by other men with lowered voice pitch (a vocal cue to dominance). A follow-up study demonstrated that self-reported dominance was positively related to menâs choice of low-pitch men as friends when judging humorous audio clips but not when judging neutral control audio clips, suggesting that humor may be important in mediating the effect of dominance on friendship choice. These studies indicate systematic variation in humor appreciation related to friendship choices which may function to promote cohesion within male partnerships based on status
The 8 Micron Phase Variation of the Hot Saturn HD 149026b
We monitor the star HD 149026 and its Saturn-mass planet at 8.0 micron over
slightly more than half an orbit using the Infrared Array Camera (IRAC) on the
Spitzer Space Telescope. We find an increase of 0.0227% +/- 0.0066% (3.4 sigma
significance) in the combined planet-star flux during this interval. The
minimum flux from the planet is 45% +/- 19% of the maximum planet flux,
corresponding to a difference in brightness temperature of 480 +/- 140 K
between the two hemispheres. We derive a new secondary eclipse depth of 0.0411%
+/- 0.0076% in this band, corresponding to a dayside brightness temperature of
1440 +/- 150 K. Our new secondary eclipse depth is half that of a previous
measurement (3.0 sigma difference) in this same bandpass by Harrington et al.
(2007). We re-fit the Harrington et al. (2007) data and obtain a comparably
good fit with a smaller eclipse depth that is consistent with our new value. In
contrast to earlier claims, our new eclipse depth suggests that this planet's
dayside emission spectrum is relatively cool, with an 8 micron brightness
temperature that is less than the maximum planet-wide equilibrium temperature.
We measure the interval between the transit and secondary eclipse and find that
that the secondary eclipse occurs 20.9 +7.2 / -6.5 minutes earlier (2.9 sigma)
than predicted for a circular orbit, a marginally significant result. This
corresponds to e*cos(omega) = -0.0079 +0.0027 / -0.0025 where e is the planet's
orbital eccentricity and omega is the argument of pericenter.Comment: 17 pages, 12 figure, accepted for publication in Ap
Observations of Extrasolar Planets During the non-Cryogenic Spitzer Space Telescope Mission
Precision infrared photometry from Spitzer has enabled the first direct
studies of light from extrasolar planets, via observations at secondary eclipse
in transiting systems. Current Spitzer results include the first longitudinal
temperature map of an extrasolar planet, and the first spectra of their
atmospheres. Spitzer has also measured a temperature and precise radius for the
first transiting Neptune-sized exoplanet, and is beginning to make precise
transit timing measurements to infer the existence of unseen low mass planets.
The lack of stellar limb darkening in the infrared facilitates precise radius
and transit timing measurements of transiting planets. Warm Spitzer will be
capable of a precise radius measurement for Earth-sized planets transiting
nearby M-dwarfs, thereby constraining their bulk composition. It will continue
to measure thermal emission at secondary eclipse for transiting hot Jupiters,
and be able to distinguish between planets having broad band emission versus
absorption spectra. It will also be able to measure the orbital phase variation
of thermal emission for close-in planets, even non-transiting planets, and
these measurements will be of special interest for planets in eccentric orbits.
Warm Spitzer will be a significant complement to Kepler, particularly as
regards transit timing in the Kepler field. In addition to studying close-in
planets, Warm Spitzer will have significant application in sensitive imaging
searches for young planets at relatively large angular separations from their
parent stars.Comment: 12 pages, 7 figures, to appear in "Science Opportunities for the Warm
Spitzer Mission
A map of the day-night contrast of the extrasolar planet HD 189733b
"Hot Jupiter" extrasolar planets are expected to be tidally locked because
they are close (<0.05 astronomical units, where 1 AU is the average Sun-Earth
distance) to their parent stars, resulting in permanent daysides and
nightsides. By observing systems where the planet and star periodically eclipse
each other, several groups have been able to estimate the temperatures of the
daysides of these planets. A key question is whether the atmosphere is able to
transport the energy incident upon the dayside to the nightside, which will
determine the temperature at different points on the planet's surface. Here we
report observations of HD 189733, the closest of these eclipsing planetary
systems, over half an orbital period, from which we can construct a 'map' of
the distribution of temperatures. We detected the increase in brightness as the
dayside of the planet rotated into view. We estimate a minimum brightness
temperature of 973 +/- 33 K and a maximum brightness temperature of 1212 +/- 11
K at a wavelength of 8 microns, indicating that energy from the irradiated
dayside is efficiently redistributed throughout the atmosphere, in contrast to
a recent claim for another hot Jupiter. Our data indicate that the peak
hemisphere-integrated brightness occurs 166 degrees before opposition,
corresponding to a hot spot shifted east of the substellar point. The secondary
eclipse (when the planet moves behind the star) occurs 120 +/- 24 s later than
predicted, which may indicate a slightly eccentric orbit.Comment: To appear in the May 10 2007 issue of Nature, 10 pages, 2 black and
white figures, 1 colo
Comparative analysis of the Geobacillus hemicellulose utilization locus reveals a highly variable target for improved hemicellulolysis
BACKGROUND: Members of the thermophilic genus Geobacillus can grow at high temperatures and produce a
battery of thermostable hemicellulose hydrolytic enzymes, making them ideal candidates for the bioconversion of
biomass to value-added products. To date the molecular determinants for hemicellulose degradation and utilization
have only been identified and partially characterized in one strain, namely Geobacillus stearothermophilus T-6, where
they are clustered in a single genetic locus.
RESULTS: Using the G. stearothermophilus T-6 hemicellulose utilization locus as genetic marker, orthologous
hemicellulose utilization (HUS) loci were identified in the complete and partial genomes of 17/24 Geobacillus strains.
These HUS loci are localized on a common genomic island. Comparative analyses of these loci revealed extensive
variability among the Geobacillus hemicellulose utilization systems, with only seven out of 41â68 proteins encoded
on these loci conserved among the HUS+ strains. This translates into extensive differences in the hydrolytic enzymes,
transport systems and metabolic pathways employed by Geobacillus spp. to degrade and utilize hemicellulose polymers.
CONCLUSIONS: The genetic variability among the Geobacillus HUS loci implies that they have variable capacities to
degrade hemicellulose polymers, or that they may degrade distinct polymers, as are found in different plant species and
tissues. The data from this study can serve as a basis for the genetic engineering of a Geobacillus strain(s) with an
improved capacity to degrade and utilize hemicellulose.This project was partially funded through the University of Pretoria
Postdoctoral Fellowship Programme and the National Research Foundation
(NRF) Research Career Advancement (RCA) Fellowship Programme.http://www.biomedcentral.com/bmcgenomics/am201
The Probable Detection of SN 1923A: The Oldest Radio Supernova?
Based upon the results of VLA observations, we report the detection of two
unresolved radio sources that are coincident with the reported optical position
of SN 1923A in M83. For the source closest to the SN position, the flux density
was determined to be 0.30 +/- 0.05 mJy at 20 cm and 0.093 +/- 0.028 mJy at 6
cm. The flux density of the second nearby source was determined to be 0.29 +/-
0.05 at 20 cm and 0.13 +/- 0.028 at 6 cm. Both sources are non-thermal with
spectral indices of alpha = -1.0 +/- 0.30 and -0.69 +/- 0.24, respectively. SN
1923A has been designated as a Type II-P. No Type II-P (other than SN 1987A)
has been detected previously in the radio. The radio emission from both sources
appears to be fading with time. At an age of approximately 68 years when we
observed it, this would be the oldest radio supernova (of known age) yet
detected
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