2,303 research outputs found
Signatures in a Giant Radio Galaxy of a Cosmological Shock Wave at Intersecting Filaments of Galaxies
Sensitive images of low-level, Mpc-sized radio cocoons offer new
opportunities to probe large scale intergalactic gas flows outside clusters of
galaxies. New radio images of high surface brightness sensitivity at
strategically chosen wavelengths of the giant radio galaxy NGC 315 (Mack et al.
1997,1998) reveal significant asymmetries and particularities in the
morphology, radio spectrum and polarization of the ejected radio plasma. We
argue that the combination of these signatures provides a sensitive probe of an
environmental shock wave. Analysis of optical redshifts in NGC 315 vicinity
confirms its location to be near, or at a site of large-scale flow collisions
in the 100 Mpc sized Pisces-Perseus Supercluster region. NGC 315 resides at the
intersection of several galaxy filaments, and its radio plasma serves there as
a `weather station' (Burns 1998) probing the flow of the elusive and previously
invisible IGM gas. If our interpretation is correct, this is the first
indication for a shock wave in flows caused by the cosmological large scale
structure formation, which is located in a filament of galaxies. The
possibility that the putative shock wave is a source of gamma-rays and ultra
high energy cosmic rays is briefly discussed.Comment: accepted by Astrophysical Journal Letters, 4 pages, 3 figures (incl.
2 color), uses emulateapj5.sty (included), aastex.sty (included) and
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Plasma natriuretic peptide levels reflect changes in heart failure symptoms, left ventricular size and function after surgical mitral valve repair
Background and aim: N-terminal pro-B-type natriuretic peptide (NT-proBNP) has diagnostic and prognostic value in patients with heart failure. The present prospective study was designed to assess whether changes in NT-proBNP levels after surgical mitral valve repair reflect changes in heart failure symptoms an
Comprehensive Characterization of Solar Eruptions with Remote and In-Situ Observations, and Modeling : The Major Solar Events on 4 November 2015
Solar energetic particles (SEPs) are an important product of solar activity. They are connected to solar active regions and flares, coronal mass ejections (CMEs), EUV waves, shocks, Type II and III radio emissions, and X-ray bursts. These phenomena are major probes of the partition of energy in solar eruptions, as well as for the organization, dynamics, and relaxation of coronal and interplanetary magnetic fields. Many of these phenomena cause terrestrial space weather, posing multiple hazards for humans and their technology from space to the ground. Since particular flares, shocks, CMEs, and EUV waves produce SEP events but others do not, since propagation effects from the low corona to 1 AU appear important for some events but not others, and since Type II and III radio emissions and X-ray bursts are sometimes produced by energetic particles leaving these acceleration sites, it is necessary to study the whole system with a multi-frequency and multi-instrument perspective that combines both in-situ and remote observations with detailed modeling of phenomena. This article demonstrates this comprehensive approach and shows its necessity by analyzing a trio of unusual and striking solar eruptions, radio and X-ray bursts, and SEP events that occurred on 4 November 2015. These events show both strong similarities and differences from standard events and each other, despite having very similar interplanetary conditions and only two flare sites and CME genesis regions. They are therefore major targets for further in-depth observational studies, and for testing both existing and new theories and models. We present the complete suite of relevant observations, complement them with initial modeling results for the SEPs and interplanetary magnetic connectivity, and develop a plausible scenario for the eruptions. Perhaps controversially, the SEPs appear to be reasonably modelled and evidence points to significant non-Parker magnetic fields. Based on the very limited modeling available, we identify the aspects that are and are not understood, and we discuss ideas that may lead to improved understanding of the SEP, radio, and space-weather events.Peer reviewe
Natural images from the birthplace of the human eye
Here we introduce a database of calibrated natural images publicly available
through an easy-to-use web interface. Using a Nikon D70 digital SLR camera, we
acquired about 5000 six-megapixel images of Okavango Delta of Botswana, a
tropical savanna habitat similar to where the human eye is thought to have
evolved. Some sequences of images were captured unsystematically while
following a baboon troop, while others were designed to vary a single parameter
such as aperture, object distance, time of day or position on the horizon.
Images are available in the raw RGB format and in grayscale. Images are also
available in units relevant to the physiology of human cone photoreceptors,
where pixel values represent the expected number of photoisomerizations per
second for cones sensitive to long (L), medium (M) and short (S) wavelengths.
This database is distributed under a Creative Commons Attribution-Noncommercial
Unported license to facilitate research in computer vision, psychophysics of
perception, and visual neuroscience.Comment: Submitted to PLoS ON
TMEM258 Is a Component of the Oligosaccharyltransferase Complex Controlling ER Stress and Intestinal Inflammation
Summary - Significant insights into disease pathogenesis have been gleaned from population-level genetic studies; however, many loci associated with complex genetic disease contain numerous genes, and phenotypic associations cannot be assigned unequivocally. In particular, a gene-dense locus on chromosome 11 (61.5–61.65 Mb) has been associated with inflammatory bowel disease, rheumatoid arthritis, and coronary artery disease. Here, we identify TMEM258 within this locus as a central regulator of intestinal inflammation. Strikingly, Tmem258 haploinsufficient mice exhibit severe intestinal inflammation in a model of colitis. At the mechanistic level, we demonstrate that TMEM258 is a required component of the oligosaccharyltransferase complex and is essential for N-linked protein glycosylation. Consequently, homozygous deficiency of Tmem258 in colonic organoids results in unresolved endoplasmic reticulum (ER) stress culminating in apoptosis. Collectively, our results demonstrate that TMEM258 is a central mediator of ER quality control and intestinal homeostasis.Leona M. and Harry B. Helmsley Charitable Trust (2014PG-IBD016)Crohn's and Colitis Foundation of AmericaNational Institutes of Health (U.S.) (grant DK043351)National Institutes of Health (U.S.) (grant DK097485
Search for Yukawa Production of a Light Neutral Higgs Boson at LEP
Within a Two-Higgs-Doublet Model (2HDM) a search for a light Higgs boson in
the mass range of 4-12 GeV has been performed in the Yukawa process e+e- -> b
bbar A/h -> b bbar tau+tau-, using the data collected by the OPAL detector at
LEP between 1992 and 1995 in e+e- collisions at about 91 GeV centre-of-mass
energy. A likelihood selection is applied to separate background and signal.
The number of observed events is in good agreement with the expected
background. Within a CP-conserving 2HDM type II model the cross-section for
Yukawa production depends on xiAd = |tan beta| and xihd = |sin alpha/cos beta|
for the production of the CP-odd A and the CP-even h, respectively, where tan
beta is the ratio of the vacuum expectation values of the Higgs doublets and
alpha is the mixing angle between the neutral CP-even Higgs bosons. From our
data 95% C.L. upper limits are derived for xiAd within the range of 8.5 to 13.6
and for xihd between 8.2 to 13.7, depending on the mass of the Higgs boson,
assuming a branching fraction into tau+tau- of 100%. An interpretation of the
limits within a 2HDM type II model with Standard Model particle content is
given. These results impose constraints on several models that have been
proposed to explain the recent BNL measurement of the muon anomalous magnetic
moment.Comment: 24 pages, 9 figures, Submitted to Euro. Phys. J.
Measurement of triple gauge boson couplings from WW production at LEP energies up to 189 GeV
A measurement of triple gauge boson couplings is presented, based on W-pair
data recorded by the OPAL detector at LEP during 1998 at a centre-of-mass
energy of 189 GeV with an integrated luminosity of 183 pb^-1. After combining
with our previous measurements at centre-of-mass energies of 161-183 GeV we
obtain k_g=0.97 +0.20 -0.16, g_1^z=0.991 +0.060 -0.057 and lambda_g=-0.110
+0.058 -0.055, where the errors include both statistical and systematic
uncertainties and each coupling is determined by setting the other two
couplings to their SM values. These results are consistent with the Standard
Model expectations.Comment: 28 pages, 8 figures, submitted to Eur. Phys. J.
Tests of model of color reconnection and a search for glueballs using gluon jets with a rapidity gap
Gluon jets with a mean energy of 22 GeV and purity of 95% are selected from
hadronic Z0 decay events produced in e+e- annihilations. A subsample of these
jets is identified which exhibits a large gap in the rapidity distribution of
particles within the jet. After imposing the requirement of a rapidity gap, the
gluon jet purity is 86%. These jets are observed to demonstrate a high degree
of sensitivity to the presence of color reconnection, i.e. higher order QCD
processes affecting the underlying color structure. We use our data to test
three QCD models which include a simulation of color reconnection: one in the
Ariadne Monte Carlo, one in the Herwig Monte Carlo, and the other by Rathsman
in the Pythia Monte Carlo. We find the Rathsman and Ariadne color reconnection
models can describe our gluon jet measurements only if very large values are
used for the cutoff parameters which serve to terminate the parton showers, and
that the description of inclusive Z0 data is significantly degraded in this
case. We conclude that color reconnection as implemented by these two models is
disfavored. The signal from the Herwig color reconnection model is less clear
and we do not obtain a definite conclusion concerning this model. In a separate
study, we follow recent theoretical suggestions and search for glueball-like
objects in the leading part of the gluon jets. No clear evidence is observed
for these objects.Comment: 42 pages, 18 figure
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