943 research outputs found
X-ray total mass estimate for the nearby relaxed cluster A3571
We constrain the total mass distribution in the cluster A3571, combining
spatially resolved ASCA temperature data with ROSAT imaging data with the
assumption that the cluster is in hydrostatic equilibrium. The total mass
within r_500 (1.7/h_50 Mpc) is M_500 = 7.8[+1.4,-2.2] 10^14/ h_50 Msun at 90%
confidence, 1.1 times smaller than the isothermal estimate. The Navarro, Frenk
& White ``universal profile'' is a good description of the dark matter density
distribution in A3571. The gas density profile is shallower than the dark
matter profile, scaling as r^{-2.1} at large radii, leading to a monotonically
increasing gas mass fraction with radius. Within r_500 the gas mass fraction
reaches a value of f_gas = 0.19[+0.06,-0.03] h_50^{-3/2} (90% confidence
errors). Assuming that this value of f_gas is a lower limit for the the
universal value of the baryon fraction, we estimate the 90% confidence upper
limit of the cosmological matter density to be Omega_m < 0.4.Comment: 10 pages, 4 figures, accepted by Ap
Red Galaxy Growth and the Halo Occupation Distribution
We have traced the past 7 Gyr of red galaxy stellar mass growth within dark
matter halos. We have determined the halo occupation distribution, which
describes how galaxies reside within dark matter halos, using the observed
luminosity function and clustering of 40,696 0.2<z<1.0 red galaxies in Bootes.
Half of 10^{11.9} Msun/h halos host a red central galaxy, and this fraction
increases with increasing halo mass. We do not observe any evolution of the
relationship between red galaxy stellar mass and host halo mass, although we
expect both galaxy stellar masses and halo masses to evolve over cosmic time.
We find that the stellar mass contained within the red population has doubled
since z=1, with the stellar mass within red satellite galaxies tripling over
this redshift range. In cluster mass halos most of the stellar mass resides
within satellite galaxies and the intra-cluster light, with a minority of the
stellar mass residing within central galaxies. The stellar masses of the most
luminous red central galaxies are proportional to halo mass to the power of a
third. We thus conclude that halo mergers do not always lead to rapid growth of
central galaxies. While very massive halos often double in mass over the past 7
Gyr, the stellar masses of their central galaxies typically grow by only 30%.Comment: Accepted for publication in the ApJ. 34 pages, 22 Figures, 5 Table
Transmission potential of Rift Valley fever virus over the course of the 2010 epidemic in South Africa.
A Rift Valley fever (RVF) epidemic affecting animals on domestic livestock farms was reported in South Africa during January-August 2010. The first cases occurred after heavy rainfall, and the virus subsequently spread countrywide. To determine the possible effect of environmental conditions and vaccination on RVF virus transmissibility, we estimated the effective reproduction number (Re) for the virus over the course of the epidemic by extending the Wallinga and Teunis algorithm with spatial information. Re reached its highest value in mid-February and fell below unity around mid-March, when vaccination coverage was 7.5%-45.7% and vector-suitable environmental conditions were maintained. The epidemic fade-out likely resulted first from the immunization of animals following natural infection or vaccination. The decline in vector-suitable environmental conditions from April onwards and further vaccination helped maintain Re below unity. Increased availability of vaccine use data would enable evaluation of the effect of RVF vaccination campaigns
The transcription factor PPARα is overexpressed and is associated with a favourable prognosis in IDH-wildtype primary glioblastoma
© 2016 John Wiley & Sons Ltd Aims: PPARα agonists are in current clinical use as hypolipidaemic agents and show significant antineoplastic effects in human glioblastoma models. To date however, the expression of PPARα in large-scale glioblastoma datasets has not been examined. We aimed to investigate the expression of the transcription factor PPARα in primary glioblastoma, the relationship between PPARα expression and patients’ clinicopathological features and other molecular markers associated with gliomagenesis. Methods and results: With protein immunoblotting techniques and reverse transcription quantitative real-time PCR, PPARα was found to be significantly overexpressed in glioblastoma compared with control brain tissue (P = 0.032 and P = 0.005). PPARA gene expression was found to be enriched in the classical glioblastoma subtype within The Cancer Genome Atlas (TCGA) dataset. Although not associated with overall survival when assessed by immunohistochemistry, cross-validation with the TCGA dataset and multivariate analyses identified PPARA gene expression as an independent prognostic marker for overall survival (P = 0.042). Finally, hierarchical clustering revealed novel, significant associations between high PPARA expression and a putative set of glioblastoma molecular mediators including EMX2, AQP4, and NTRK2. Conclusions: PPARα is overexpressed in primary glioblastoma and high PPARA expression functions as an independent prognostic marker in the glioblastoma TCGA dataset. Further studies are required to explore genetic associations with high PPARA expression and to analyse the predictive role of PPARα expression in glioblastoma models in response to PPARα agonists
Utilization of a deoxynucleoside diphosphate substrate by HIV reverse transcriptase
Background: Deoxynucleoside triphosphates (dNTPs) are the normal substrates for DNA sysnthesis is catalyzed by polymerases such as HIV-1 reverse transcriptase (RT). However, substantial amounts of deoxynucleoside diphosphates (dNDPs) are also present in the cell. Use of dNDPs in HIV-1 DNA sysnthesis could have significant implications for the efficacy of nucleoside RT inhibitors such as AZT which are first line therapeutics fro treatment of HIV infection. Our earlier work on HIV-1 reverse transcriptase (RT) suggested that the interaction between the γ phosphate of the incoming dNTP and RT residue K65 in the active site is not essential for dNTP insertion, implying that this polymerase may be able to insert dNPs in addition to dNTPs. Methodology/Principal Findings: We examined the ability of recombinant wild type (wt) and mutant RTs with substitutions at residue K65 to utilize a dNDP substrate in primer extension reactions. We found that wild type HIV-1 RT indeed catalyzes incorporation of dNDP substrates whereas RT with mutations of residue K645 were unable to catalyze this reaction. Wild type HIV-1 RT also catalyzed the reverse reaction, inorganic phosphate-dependent phosphorolysis. Nucleotide-mediated phosphorolytic removal of chain-terminating 3′-terminal nucleoside inhibitors such as AZT forms the basis of HIV-1 resistance to such drugs, and this removal is enhanced by thymidine analog mutations (TAMs). We found that both wt and TAM-containing RTs were able to catalyze Pi-mediated phosphorolysis of 3′-terminal AZT at physiological levels of Pi with an efficacy similar to that for ATP-dependent AZT-excision. Conclusion: We have identified two new catalytic function of HIV-1 RT, the use of dNDPs as substrates for DNA synthesis, and the use of Pi as substrate for phosphorolytic removal of primer 3′-terminal nucleotides. The ability to insert dNDPs has been documented for only one other DNA polymerase The RB69 DNA polymerase and the reverse reaction employing inorganic phosphate has not been documented for any DNA polymerase. Importantly, our results show that Pi-mediated phosphorolysis can contribute to AZT resistance and indicates that factors that influence HIV resistance to AZT are more complex than previously appreciated. © 2008 Garforth et al
Transmission of toxigenic Corynebacterium diphtheriae by a fully immunised resident returning from a visit to West Africa, United Kingdom, 2017.
In early 2017, a United Kingdom (UK)-born person in their 20s presented with a skin ulcer on the foot 3 weeks after returning from Ghana. The patient had last received a diphtheria-containing vaccine in 2013, completing the recommended course. MALDI-TOF of a cutaneous swab identified Corynebacterium diphtheriae. Real-time PCR ascertained the species and presence of the diphtheria toxin gene. An Elek test confirmed toxigenicity. The isolate was macrolide sensitive and penicillin resistant. The local Public Health England (PHE) Health Protection Team obtained the patient's clinical history and traced contacts to inform appropriate public health action. One close contact (in their early 80s with uncertain immunisation status who had not recently travelled) had a positive throat swab for toxigenic C. diphtheriae and reported a history of mild coryzal symptoms. Multilocus sequence typing revealed that strains from the index case and contact had Sequence Type 463. Diphtheria is extremely rare in the UK due to high vaccine coverage and this is the first documented transmission in 30 years. Clinicians and laboratory staff should remain highly suspicious of lesions in overseas travellers, even when patients are fully vaccinated. Older individuals who might not have completed a full immunisation course may have higher diphtheria susceptibility
Indication for the disappearance of reactor electron antineutrinos in the Double Chooz experiment
The Double Chooz Experiment presents an indication of reactor electron
antineutrino disappearance consistent with neutrino oscillations. A ratio of
0.944 0.016 (stat) 0.040 (syst) observed to predicted events was
obtained in 101 days of running at the Chooz Nuclear Power Plant in France,
with two 4.25 GW reactors. The results were obtained from a single 10
m fiducial volume detector located 1050 m from the two reactor cores. The
reactor antineutrino flux prediction used the Bugey4 measurement as an anchor
point. The deficit can be interpreted as an indication of a non-zero value of
the still unmeasured neutrino mixing parameter \sang. Analyzing both the rate
of the prompt positrons and their energy spectrum we find \sang = 0.086
0.041 (stat) 0.030 (syst), or, at 90% CL, 0.015 \sang 0.16.Comment: 7 pages, 4 figures, (new version after PRL referee's comments
In-situ characterization of the Hamamatsu R5912-HQE photomultiplier tubes used in the DEAP-3600 experiment
The Hamamatsu R5912-HQE photomultiplier-tube (PMT) is a novel high-quantum
efficiency PMT. It is currently used in the DEAP-3600 dark matter detector and
is of significant interest for future dark matter and neutrino experiments
where high signal yields are needed.
We report on the methods developed for in-situ characterization and
monitoring of DEAP's 255 R5912-HQE PMTs. This includes a detailed discussion of
typical measured single-photoelectron charge distributions, correlated noise
(afterpulsing), dark noise, double, and late pulsing characteristics. The
characterization is performed during the detector commissioning phase using
laser light injected through a light diffusing sphere and during normal
detector operation using LED light injected through optical fibres
Transmission of toxigenic Corynebacterium diphtheriae by a fully immunised resident returning from a visit to West Africa, United Kingdom, 2017
In early 2017, a United Kingdom (UK)-born person in their 20s presented with a skin ulcer on the foot 3 weeks after returning from Ghana. The patient had last received a diphtheria-containing vaccine in 2013, completing the recommended course. MALDI-TOF of a cutaneous swab identified Corynebacterium diphtheriae. Real-time PCR ascertained the species and presence of the diphtheria toxin gene. An Elek test confirmed toxigenicity. The isolate was macrolide sensitive and penicillin resistant. The local Public Health England (PHE) Health Protection Team obtained the patient’s clinical history and traced contacts to inform appropriate public health action. One close contact (in their early 80s with uncertain immunisation status who had not recently travelled) had a positive throat swab for toxigenic C. diphtheriae and reported a history of mild coryzal symptoms. Multilocus sequence typing revealed that strains from the index case and contact had Sequence Type 493*. Diphtheria is extremely rare in the UK due to high vaccine coverage and this is the first documented transmission in 30 years. Clinicians and laboratory staff should remain highly suspicious of lesions in overseas travellers, even when patients are fully vaccinated. Older individuals who might not have completed a full immunisation course may have higher diphtheria susceptibility
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