630 research outputs found
The census of interstellar complex organic molecules in the Class I hot corino of SVS13-A
We present the first census of the interstellar Complex Organic Molecules
(iCOMs) in the low-mass Class I protostar SVS13-A, obtained by analysing data
from the IRAM-30m Large Project ASAI (Astrochemical Surveys At IRAM). They
consist of an high-sensitivity unbiased spectral survey at the 1mm, 2mm and 3mm
IRAM bands. We detected five iCOMs: acetaldehyde (CHCHO), methyl formate
(HCOOCH), dimethyl ether (CHOCH), ethanol (CHCHOH) and
formamide (NHCHO). In addition we searched for other iCOMs and ketene
(HCCO), formic acid (HCOOH) and methoxy (CHO), whose only ketene was
detected. The numerous detected lines, from 5 to 37 depending on the species,
cover a large upper level energy range, between 15 and 254 K. This allowed us
to carry out a rotational diagram analysis and derive rotational temperatures
between 35 and 110 K, and column densities between and
cm on the 0."3 size previously determined by
interferometric observations of glycolaldehyde. These new observations clearly
demonstrate the presence of a rich chemistry in the hot corino towards SVS13-A.
The measured iCOMs abundances were compared to other Class 0 and I hot corinos,
as well as comets, previously published in the literature. We find evidence
that (i) SVS13-A is as chemically rich as younger Class 0 protostars, and (ii)
the iCOMs relative abundances do not substantially evolve during the
protostellar phase.Comment: 24 pages, MNRAS in pres
Chemical shifts and cluster structure
The 2p core-level electron binding energies of size-selected silicon cluster
ions have been determined from soft x-ray photoionization efficiency curves.
Local chemical shifts and global charging energy contributions to the 2p
binding energy can be separated, because core-level and valence-band electron
binding energies exhibit the same inverse radius dependence. The experimental
2p binding energy distributions show characteristic size-specific patterns
that are well reproduced by the corresponding electronic density of states
obtained from density functional theory modeling. These results demonstrate
that 2p binding energies in silicon clusters are dominated by initial state
effects, i.e., by the interaction with the local valence electron density, and
can thus be used to corroborate structural assignments
The Integration of Reconfigurable Filters for the Matching of Wideband Antennas
Abstract-This paper presents a technique to reduce the cost and overcome the high processing power needed to analyze the signals received by wideband antennas. The idea is based on matching a wideband antenna to a reconfigurable filter. This will allow an easier processing for the received signal and the replacement of the bank of filters needed after the antenna by one reconfigurable filter element. Two prototypes are shown to prove the validity of the proposed technique
Measuring Transit Signal Recovery in the Kepler Pipeline. III. Completeness of the Q1-Q17 DR24 Planet Candidate Catalogue, with Important Caveats for Occurrence Rate Calculations
With each new version of the Kepler pipeline and resulting planet candidate
catalogue, an updated measurement of the underlying planet population can only
be recovered with an corresponding measurement of the Kepler pipeline detection
efficiency. Here, we present measurements of the sensitivity of the pipeline
(version 9.2) used to generate the Q1-Q17 DR24 planet candidate catalog
(Coughlin et al. 2016). We measure this by injecting simulated transiting
planets into the pixel-level data of 159,013 targets across the entire Kepler
focal plane, and examining the recovery rate. Unlike previous versions of the
Kepler pipeline, we find a strong period dependence in the measured detection
efficiency, with longer (>40 day) periods having a significantly lower
detectability than shorter periods, introduced in part by an incorrectly
implemented veto. Consequently, the sensitivity of the 9.2 pipeline cannot be
cast as a simple one-dimensional function of the signal strength of the
candidate planet signal as was possible for previous versions of the pipeline.
We report on the implications for occurrence rate calculations based on the
Q1-Q17 DR24 planet candidate catalog and offer important caveats and
recommendations for performing such calculations. As before, we make available
the entire table of injected planet parameters and whether they were recovered
by the pipeline, enabling readers to derive the pipeline detection sensitivity
in the planet and/or stellar parameter space of their choice.Comment: 8 pages, 5 figures, full electronic version of Table 1 available at
the NASA Exoplanet Archive; accepted by ApJ May 2nd, 201
TDP-43 Mediated Blood-Brain Barrier Permeability and Leukocyte Infiltration Promote Neurodegeneration in a Low-Grade Systemic Inflammation Mouse Model
BACKGROUND: Neuronal cytoplasmic inclusions containing TAR DNA-binding protein 43 (TDP-43) are a neuropathological feature of several neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and Alzheimer\u27s Disease (AD). Emerging evidence also indicates that systemic inflammation may be a contributor to the pathology progression of these neurodegenerative diseases.
METHODS: To investigate the role of systemic inflammation in the progression of neuronal TDP-43 pathology, AAV9 particles driven by the UCHL1 promoter were delivered to the frontal cortex of wild-type aged mice via intracranial injections to overexpress TDP-43 or green fluorescent protein (GFP) in corticospinal motor neurons. Animals were then subjected to a low-dose (500 μg/kg) intraperitoneal E. coli lipopolysaccharide (LPS) administration challenge for 2 weeks to mimic a chronically altered low-grade systemic inflammatory state. Mice were then subjected to neurobehavioral studies, followed by biochemical and immunohistochemical analyses of the brain tissue.
RESULTS: In the present study, we report that elevated neuronal TDP-43 levels induced microglial and astrocytic activation in the cortex of injected mice followed by increased RANTES signaling. Moreover, overexpression of TDP-43 exerted abundant mouse immunoglobulin G (IgG), CD3, and CD4+ T cell infiltration as well as endothelial and pericyte activation suggesting increased blood-brain barrier permeability. The BBB permeability in TDP-43 overexpressing brains yielded the frontal cortex vulnerable to the systemic inflammatory response following LPS treatment, leading to marked neutrophil infiltration, neuronal loss, reduced synaptosome-associated protein 25 (SNAP-25) levels, and behavioral impairments in the radial arm water maze (RAWM) task.
CONCLUSIONS: These results reveal a novel role for TDP-43 in BBB permeability and leukocyte recruitment, indicating complex intermolecular interactions between an altered systemic inflammatory state and pathologically prone TDP-43 protein to promote disease progression
Amphibianâ killing chytrid in Brazil comprises both locally endemic and globally expanding populations
Chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), is the emerging infectious disease implicated in recent population declines and extinctions of amphibian species worldwide. Bd strains from regions of diseaseâ associated amphibian decline to date have all belonged to a single, hypervirulent clonal genotype (Bdâ GPL). However, earlier studies in the Atlantic Forest of southeastern Brazil detected a novel, putatively enzootic lineage (Bdâ Brazil), and indicated hybridization between Bdâ GPL and Bdâ Brazil. Here, we characterize the spatial distribution and population history of these sympatric lineages in the Brazilian Atlantic Forest. To investigate the genetic structure of Bd in this region, we collected and genotyped Bd strains along a 2400â km transect of the Atlantic Forest. Bdâ Brazil genotypes were restricted to a narrow geographic range in the southern Atlantic Forest, while Bdâ GPL strains were widespread and largely geographically unstructured. Bd population genetics in this region support the hypothesis that the recently discovered Brazilian lineage is enzootic in the Atlantic Forest of Brazil and that Bdâ GPL is a more recently expanded invasive. We collected additional hybrid isolates that demonstrate the recurrence of hybridization between panzootic and enzootic lineages, thereby confirming the existence of a hybrid zone in the Serra da Graciosa mountain range of Paraná State. Our field observations suggest that Bdâ GPL may be more infective towards native Brazilian amphibians, and potentially more effective at dispersing across a fragmented landscape. We also provide further evidence of pathogen translocations mediated by the Brazilian ranaculture industry with implications for regulations and policies on global amphibian trade.See also the Perspective by Ghosh and FisherPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/122445/1/mec13599.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/122445/2/mec13599_am.pd
Xpert MTB/RIF Assay Shows Faster Clearance of Mycobacterium tuberculosis DNA with Higher Levels of Rifapentine Exposure.
The Xpert MTB/RIF assay is both sensitive and specific as a diagnostic test. Xpert also reports quantitative output in cycle threshold (CT) values, which may provide a dynamic measure of sputum bacillary burden when used longitudinally. We evaluated the relationship between Xpert CT trajectory and drug exposure during tuberculosis (TB) treatment to assess the potential utility of Xpert CT for treatment monitoring. We obtained serial sputum samples from patients with smear-positive pulmonary TB who were consecutively enrolled at 10 international clinical trial sites participating in study 29X, a CDC-sponsored Tuberculosis Trials Consortium study evaluating the tolerability, safety, and antimicrobial activity of rifapentine at daily doses of up to 20 mg/kg of body weight. Xpert was performed at weeks 0, 2, 4, 6, 8, and 12. Longitudinal CT data were modeled using a nonlinear mixed effects model in relation to rifapentine exposure (area under the concentration-time curve [AUC]). The rate of change of CT was higher in subjects receiving rifapentine than in subjects receiving standard-dose rifampin. Moreover, rifapentine exposure, but not assigned dose, was significantly associated with rate of change in CT (P = 0.02). The estimated increase in CT slope for every additional 100 μg · h/ml of rifapentine drug exposure (as measured by AUC) was 0.11 CT/week (95% confidence interval [CI], 0.05 to 0.17). Increasing rifapentine exposure is associated with a higher rate of change of Xpert CT, indicating faster clearance of Mycobacterium tuberculosis DNA. These data suggest that the quantitative outputs of the Xpert MTB/RIF assay may be useful as a dynamic measure of TB treatment response
Spectral decomposition of internal gravity wave sea surface height in global models
Two global ocean models ranging in horizontal resolution from 1/12° to 1/48° are used to study the space and time scales of sea surface height (SSH) signals associated with internal gravity waves (IGWs). Frequency‐horizontal wavenumber SSH spectral densities are computed over seven regions of the world ocean from two simulations of the HYbrid Coordinate Ocean Model (HYCOM) and three simulations of the Massachusetts Institute of Technology general circulation model (MITgcm). High wavenumber, high‐frequency SSH variance follows the predicted IGW linear dispersion curves. The realism of high‐frequency motions (>0.87 cpd) in the models is tested through comparison of the frequency spectral density of dynamic height variance computed from the highest‐resolution runs of each model (1/25° HYCOM and 1/48° MITgcm) with dynamic height variance frequency spectral density computed from nine in situ profiling instruments. These high‐frequency motions are of particular interest because of their contributions to the small‐scale SSH variability that will be observed on a global scale in the upcoming Surface Water and Ocean Topography (SWOT) satellite altimetry mission. The variance at supertidal frequencies can be comparable to the tidal and low‐frequency variance for high wavenumbers (length scales smaller than ∼50 km), especially in the higher‐resolution simulations. In the highest‐resolution simulations, the high‐frequency variance can be greater than the low‐frequency variance at these scales.Key PointsTwo high‐resolution ocean models compare well against data in frequency spectral density of dynamic heightSea surface height frequency‐horizontal wavenumber spectral densities show high variance along internal gravity wave dispersion curvesTwo high‐resolution ocean models give different estimates of variance in high‐frequency, high wavenumber phenomenaPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139946/1/jgrc22465-sup-0002-2017JC013009-fs01.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139946/2/jgrc22465-sup-0003-2017JC013009-fs02.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139946/3/jgrc22465_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139946/4/jgrc22465.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139946/5/jgrc22465-sup-0007-2017JC013009-fs06.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139946/6/jgrc22465-sup-0009-2017JC013009-fs08.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139946/7/jgrc22465-sup-0004-2017JC013009-fs03.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139946/8/jgrc22465-sup-0005-2017JC013009-fs04.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139946/9/jgrc22465-sup-0006-2017JC013009-fs05.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139946/10/jgrc22465-sup-0001-2017JC013009-s01.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139946/11/jgrc22465-sup-0008-2017JC013009-fs07.pd
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