776 research outputs found
Representation of agency workers: the representation of agency workers in Europe at national and local level in France, Netherlands, Sweden, Poland and the UK: final report 2009
Dark Matter Constraints from a Joint Analysis of Dwarf Spheroidal Galaxy Observations with VERITAS
We present constraints on the annihilation cross section of WIMP dark matter
based on the joint statistical analysis of four dwarf galaxies with VERITAS.
These results are derived from an optimized photon weighting statistical
technique that improves on standard imaging atmospheric Cherenkov telescope
(IACT) analyses by utilizing the spectral and spatial properties of individual
photon events. We report on the results of 230 hours of observations of
five dwarf galaxies and the joint statistical analysis of four of the dwarf
galaxies. We find no evidence of gamma-ray emission from any individual dwarf
nor in the joint analysis. The derived upper limit on the dark matter
annihilation cross section from the joint analysis is at 1 TeV for the bottom quark () final state,
at 1 TeV for the tau lepton
() final state and at 1 TeV for the gauge boson () final state.Comment: 14 pages, 9 figures, published in PRD, Ascii tables containing
annihilation cross sections limits are available for download as ancillary
files with readme.txt file description of limit
Very-High-Energy -Ray Observations of the Blazar 1ES 2344+514 with VERITAS
We present very-high-energy -ray observations of the BL Lac object
1ES 2344+514 taken by the Very Energetic Radiation Imaging Telescope Array
System (VERITAS) between 2007 and 2015. 1ES 2344+514 is detected with a
statistical significance above background of in hours
(livetime) of observations, making this the most comprehensive very-high-energy
study of 1ES 2344+514 to date. Using these observations the temporal properties
of 1ES 2344+514 are studied on short and long times scales. We fit a constant
flux model to nightly- and seasonally-binned light curves and apply a
fractional variability test, to determine the stability of the source on
different timescales. We reject the constant-flux model for the 2007-2008 and
2014-2015 nightly-binned light curves and for the long-term seasonally-binned
light curve at the level. The spectra of the time-averaged emission
before and after correction for attenuation by the extragalactic background
light are obtained. The observed time-averaged spectrum above 200 GeV is
satisfactorily fitted () by a power-law function with
index and extends to at least 8
TeV. The extragalactic-background-light-deabsorbed spectrum is adequately fit
() by a power-law function with index while an F-test indicates that the power-law with
exponential cutoff function provides a marginally-better fit ( =
) at the 2.1 level. The source location is found to be
consistent with the published radio location and its spatial extent is
consistent with a point source.Comment: 7 pages, 2 figures. Published in Monthly Notices of the Royal
Astronomical Societ
A search for spectral hysteresis and energy-dependent time lags from X-ray and TeV gamma-ray observations of Mrk 421
Blazars are variable emitters across all wavelengths over a wide range of
timescales, from months down to minutes. It is therefore essential to observe
blazars simultaneously at different wavelengths, especially in the X-ray and
gamma-ray bands, where the broadband spectral energy distributions usually
peak.
In this work, we report on three "target-of-opportunity" (ToO) observations
of Mrk 421, one of the brightest TeV blazars, triggered by a strong flaring
event at TeV energies in 2014. These observations feature long, continuous, and
simultaneous exposures with XMM-Newton (covering X-ray and optical/ultraviolet
bands) and VERITAS (covering TeV gamma-ray band), along with contemporaneous
observations from other gamma-ray facilities (MAGIC and Fermi-LAT) and a number
of radio and optical facilities. Although neither rapid flares nor significant
X-ray/TeV correlation are detected, these observations reveal subtle changes in
the X-ray spectrum of the source over the course of a few days. We search the
simultaneous X-ray and TeV data for spectral hysteresis patterns and time
delays, which could provide insight into the emission mechanisms and the source
properties (e.g. the radius of the emitting region, the strength of the
magnetic field, and related timescales). The observed broadband spectra are
consistent with a one-zone synchrotron self-Compton model. We find that the
power spectral density distribution at Hz from the
X-ray data can be described by a power-law model with an index value between
1.2 and 1.8, and do not find evidence for a steepening of the power spectral
index (often associated with a characteristic length scale) compared to the
previously reported values at lower frequencies.Comment: 45 pages, 15 figure
The combination of electron capture dissociation and fixed charge derivatization increases sequence coverage for O-glycosylated and O-phosphorylated peptides
Calmodulin-like proteins localized to the conoid regulate motility and cell invasion by Toxoplasma gondii
Toxoplasma gondii contains an expanded number of calmodulin (CaM)-like proteins whose functions are poorly understood. Using a combination of CRISPR/Cas9-mediated gene editing and a plant-like auxin-induced degron (AID) system, we examined the roles of three apically localized CaMs. CaM1 and CaM2 were individually dispensable, but loss of both resulted in a synthetic lethal phenotype. CaM3 was refractory to deletion, suggesting it is essential. Consistent with this prediction auxin-induced degradation of CaM3 blocked growth. Phenotypic analysis revealed that all three CaMs contribute to parasite motility, invasion, and egress from host cells, and that they act downstream of microneme and rhoptry secretion. Super-resolution microscopy localized all three CaMs to the conoid where they overlap with myosin H (MyoH), a motor protein that is required for invasion. Biotinylation using BirA fusions with the CaMs labeled a number of apical proteins including MyoH and its light chain MLC7, suggesting they may interact. Consistent with this hypothesis, disruption of MyoH led to degradation of CaM3, or redistribution of CaM1 and CaM2. Collectively, our findings suggest these CaMs may interact with MyoH to control motility and cell invasion
Recommended from our members
A network analysis to identify mediators of germline-driven differences in breast cancer prognosis.
Identifying the underlying genetic drivers of the heritability of breast cancer prognosis remains elusive. We adapt a network-based approach to handle underpowered complex datasets to provide new insights into the potential function of germline variants in breast cancer prognosis. This network-based analysis studies ~7.3 million variants in 84,457 breast cancer patients in relation to breast cancer survival and confirms the results on 12,381 independent patients. Aggregating the prognostic effects of genetic variants across multiple genes, we identify four gene modules associated with survival in estrogen receptor (ER)-negative and one in ER-positive disease. The modules show biological enrichment for cancer-related processes such as G-alpha signaling, circadian clock, angiogenesis, and Rho-GTPases in apoptosis
Centric diatoms of large rivers and tributaries in Hungary: morphology and biogeographic distribution
Centric diatoms of 107 different Hungarian running waters were investigated. Among them the largest was the River Danube, from which more than one hundred plankton samples were analysed by scanning electron microscopy (SEM). Only one sample was analysed from creeks, which were the smallest running waters analysed in this study. There were also channels with slow currents flowing out of rivers or connecting different rivers.In total, 41 centric taxa belonging to 11 genera were found during this study. The average number of taxa found in a single watercourse was 7, the maximum 40 and the minimum 1. Cyclotella meneghiniana was the most frequently encountered species (present in 60% ofsites). Twelve taxa were found in more than 20% of sites, 7 taxa between 5â10% and 6 taxa only in one site
Applications of Site-Specific Labeling to Study HAMLET, a Tumoricidal Complex of α-Lactalbumin and Oleic Acid
umor cells), and its tumoricidal activity has been well established.-acetylgalactosaminyltransferase II (ppGalNAc-T2) and further conjugated with aminooxy-derivatives of fluoroprobe or biotin molecules.We found that the molten globule form of hLA and αD-hLA proteins, with or without C-terminal extension, and with and without the conjugated fluoroprobe or biotin molecule, readily form a complex with OA and exhibits tumoricidal activity similar to HAMLET made with full-length hLA protein. The confocal microscopy studies with fluoroprobe-labeled samples show that these proteins are internalized into the cells and found even in the nucleus only when they are complexed with OA. The HAMLET conjugated with a single biotin molecule will be a useful tool to identify the cellular components that are involved with it in the tumoricidal activity
- âŠ