2,399 research outputs found
Delta and gamma oscillations in operculo-insular cortex underlie innocuous cold thermosensation
Cold-sensitive and nociceptive neural pathways interact to shape the quality and intensity of thermal and pain perception. Yet the central processing of cold thermosensation in the human brain has not been extensively studied. Here, we used magnetoencephalography and EEG in healthy volunteers to investigate the time course (evoked fields and potentials) and oscillatory activity associated with the perception of cold temperature changes. Nonnoxious cold stimuli consisting of Δ3°C and Δ5°C decrements from an adapting temperature of 35°C were delivered on the dorsum of the left hand via a contact thermode. Cold-evoked fields peaked at around 240 and 500 ms, at peak latencies similar to the N1 and P2 cold-evoked potentials. Importantly, cold-related changes in oscillatory power indicated that innocuous thermosensation is mediated by oscillatory activity in the range of delta (1–4 Hz) and gamma (55–90 Hz) rhythms, originating in operculo-insular cortical regions. We suggest that delta rhythms coordinate functional integration between operculo-insular and frontoparietal regions, while gamma rhythms reflect local sensory processing in operculo-insular areas
An anomalous extinction law in the Cep OB3b young cluster: Evidence for dust processing during gas dispersal
© 2014. The American Astronomical Society. All rights reserved. We determine the extinction law through Cep OB3b, a young cluster of 3000 stars undergoing gas dispersal. The extinction is measured toward 76 background K giants identified with MMT/Hectospec spectra. Color excess ratios were determined toward each of the giants using V and R photometry from the literature, g, r, i, and z photometry from the Sloan Digital Sky Survey and J, H, and Ks photometry from the Two Micron All Sky Survey. These color excess ratios were then used to construct the extinction law through the dusty material associated with Cep OB3b. The extinction law through Cep OB3b is intermediate between the RV = 3.1 and RV = 5 laws commonly used for the diffuse atomic interstellar medium and dense molecular clouds, respectively. The dependence of the extinction law on line-of-sight AV is investigated and we find the extinction law becomes shallower for regions with AV > 2.5 mag. We speculate that the intermediate dust law results from dust processing during the dispersal of the molecular cloud by the cluster.Support for this work was provided by the National Science
Foundation award AST-1009564. This research has made
use of the NASA/IPAC Infrared Science Archive, which is
operated by the Jet Propulsion Laboratory, California Institute
of Technology, under contract with the National Aeronautics
and Space Administration. This publication makes
use of data products from the Two Micron All Sky Survey,
which is a joint project of the University of Massachusetts
and the Infrared Processing and Analysis Center/California
Institute of Technology, funded by the National Aeronautics
and Space Administration and the National Science Foundation
and JPL support from SAO/JPL SV4-74011. Funding for
SDSS-III has been provided by the Alfred P. Sloan Foundation,
the Participating Institutions, the National Science Foundation,
and the U.S. Department of Energy Office of Science.
The SDSS-III web site is http://www.sdss3.org/. SDSS-III is
managed by the Astrophysical Research Consortium for the Participating
Institutions of the SDSS-III Collaboration including
the University of Arizona, the Brazilian Participation Group,
Brookhaven National Laboratory, University of Cambridge,
Carnegie Mellon University, University of Florida, the French
Participation Group, the German Participation Group, Harvard
University, the Instituto de Astrofisica de Canarias, the Michigan
State/Notre Dame/JINA Participation Group, Johns Hopkins
University, Lawrence Berkeley National Laboratory, Max
Planck Institute for Astrophysics, Max Planck Institute for Extraterrestrial
Physics, New Mexico State University, New York
University, Ohio State University, Pennsylvania State University,
University of Portsmouth, Princeton University, the Spanish
Participation Group, University of Tokyo, University of
Utah, Vanderbilt University, University of Virginia, University
of Washington, and Yale University
Surface Mean-Square Amplitudes of Vibration for Nacl
Journals published by the American Physical Society can be found at http://journals.aps.org
Vacuum Ambiguity in de Sitter Space at Strong Coupling
It is well known that in the weak coupling regime, quantum field theories in
de Sitter space do not have a unique vacuum, but a class of vacua parametrized
by a complex parameter , i.e., the so-called -vacua. In this
article, using gauge/gravity duality, we calculate the symmetric two-point
function of strongly coupled supersymmetric Yang-Mills theory on
. We find that there is a class of de Sitter invariant vacua,
parametrized by a set of complex parameters .Comment: 17 pages in JHEP style, references adde
A genome guided evaluation of the Lab4 probiotic consortium
In this study, we present the draft genome sequences of the Lab4 probiotic consortium using whole genome sequencing. Draft genome sequences were retrieved and deposited for each of the organisms; PRJNA559984 for B. bifidum CUL20, PRJNA482335 for Lactobacillus acidophilus CUL60, PRJNA482434 for Lactobacillus acid. Probiogenomic in silico analyses confirmed existing taxonomies and identified the presence putative gene sequences that were functionally related to the performance of each organism during in vitro assessments of bile and acid tolerability, adherence to enterocytes and susceptibility to antibiotics. Predictions of genomic stability identified no significant risk of horizontal gene transfer in any of the Lab4 strains and the absence of both antibiotic resistance and virulence genes. These observations were supported by the outcomes of acute phase and repeat dose tolerability studies in Wistar rats where challenge with high doses of Lab4 did not result in any mortalities, clinical/histopathological abnormalities nor indications of systemic toxicity. Detection of increased numbers of lactobacilli and bifidobacteria in the faeces of supplemented rats implied an ability to survive transit through the gastrointestinal tract and/or impact upon the intestinal microbiota composition. In summary, this study provides in silico, in vitro and in vivo support for probiotic functionality and the safety of the Lab4 consortium
Planetary Nebulae as standard candles XI. Application to Spiral Galaxies
We report the results of an [O III] lambda 5007 survey for planetary nebulae
(PN) in three spiral galaxies: M101 (NGC 5457), M51 (NGC 5194/5195) and M96
(NGC 3368). By comparing on-band/off-band [O III] lambda 5007 images with
images taken in H-alpha and broadband R, we identify 65, 64 and 74 PN
candidates in each galaxy, respectively. From these data, an adopted M31
distance of 770 kpc, and the empirical planetary nebula luminosity function
(PNLF), we derive distances to M101, M51, and M96 of 7.7 +/- 0.5, 8.4 +/- 0.6,
and 9.6 +/- 0.6 Mpc. These observations demonstrate that the PNLF technique can
be successfully applied to late-type galaxies, and provide an important overlap
between the Population I and Population II distance scales. We also discuss
some special problems associated with using the PNLF in spiral galaxies,
including the effects of dust and the possible presence of [O III] bright
supernova remnants.Comment: 38 pages, TeX, with tables included but not figures. Uses epsf.tex
and kpnobasic.tex. To be published in the Astophysical Journal. Full paper is
available at http://www.astro.psu.edu/users/johnf/Text/research.htm
Surplus Photosynthetic Antennae Complexes Underlie Diagnostics of Iron Limitation in a Cyanobacterium
Chlorophyll fluorescence from phytoplankton provides a tool to assess iron limitation in the oceans, but the physiological mechanism underlying the fluorescence response is not understood. We examined fluorescence properties of the model cyanobacterium Synechocystis PCC6803 and a ΔisiA knock-out mutant of the same species grown under three culture conditions which simulate nutrient conditions found in the open ocean: (1) nitrate and iron replete, (2) limiting-iron and high-nitrate, representative of natural high-nitrate, low-chlorophyll regions, and (3) iron and nitrogen co-limiting. We show that low variable fluorescence, a key diagnostic of iron limitation, results from synthesis of antennae complexes far in excess of what can be accommodated by the iron-restricted pool of photosynthetic reaction centers. Under iron and nitrogen co-limiting conditions, there are no excess antennae complexes and variable fluorescence is high. These results help to explain the well-established fluorescence characteristics of phytoplankton in high-nutrient, low-chlorophyll ocean regions, while also accounting for the lack of these properties in low-iron, low-nitrogen regions. Importantly, our results complete the link between unique molecular consequences of iron stress in phytoplankton and global detection of iron stress in natural populations from space
Increased Oxidative Burden Associated with Traffic Component of Ambient Particulate Matter at Roadside and Urban Background Schools Sites in London
As the incidence of respiratory and allergic symptoms has been reported to be increased in children attending schools in close proximity to busy roads, it was hypothesised that PM from roadside schools would display enhanced oxidative potential (OP). Two consecutive one-week air quality monitoring campaigns were conducted at seven school sampling sites, reflecting roadside and urban background in London. Chemical characteristics of size fractionated particulate matter (PM) samples were related to the capacity to drive biological oxidation reactions in a synthetic respiratory tract lining fluid. Contrary to hypothesised contrasts in particulate OP between school site types, no robust size-fractionated differences in OP were identified due high temporal variability in concentrations of PM components over the one-week sampling campaigns. For OP assessed both by ascorbate (OPAA m−3) and glutathione (OPGSH m−3) depletion, the highest OP per cubic metre of air was in the largest size fraction, PM1.9–10.2. However, when expressed per unit mass of particles OPAA µg−1 showed no significant dependence upon particle size, while OPGSH µg−1 had a tendency to increase with increasing particle size, paralleling increased concentrations of Fe, Ba and Cu. The two OP metrics were not significantly correlated with one another, suggesting that the glutathione and ascorbate depletion assays respond to different components of the particles. Ascorbate depletion per unit mass did not show the same dependence as for GSH and it is possible that other trace metals (Zn, Ni, V) or organic components which are enriched in the finer particle fractions, or the greater surface area of smaller particles, counter-balance the redox activity of Fe, Ba and Cu in the coarse particles. Further work with longer-term sampling and a larger suite of analytes is advised in order to better elucidate the determinants of oxidative potential, and to fuller explore the contrasts between site types.\ud
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