1,043 research outputs found
Sum rules, plasma frequencies and Hall phenomenology in holographic plasmas
We study the AC optical and hall conductivities of Dp/Dq-branes intersections
in the probe approximation and use sum-rules to study various associated
transport coefficients. We determine that the presence of massive fundamental
matter, as compared to massless fundamental matter described holographically by
a theory with no dimensional defects, reduces the plasma frequency. We further
show that this is not the case when the brane intersections include defects. We
discuss in detail how to implement correctly the regularization of retarded
Green's functions so that the dispersion relations are satisfied and the low
energy behaviour of the system is physically realistic.Comment: 25 pages, 5 figures. v2.minor changes, published versio
The burst mode of accretion in massive star formation with stellar inertia
This is the author accepted manuscript. The final version is available from Oxford University Press via the DOI in this recordData availability: This research made use of the PLUTO code developed at the University of Torino by A. Mignone (http://plutocode.ph.unito.it/). The figures have been produced using the Matplotlib plotting library for the Python programming language (https://matplotlib.org/). The data underlying this article will be shared on reasonable request to the corresponding author.The burst mode of accretion in massive star formation is a scenario linking
the initial gravitational collapse of parent pre-stellar cores to the
properties of their gravitationally unstable discs and of their
accretion-driven bursts. In this study, we present a series of high-resolution
3D radiation-hydrodynamics numerical simulations for young massive stars formed
out of collapsing 100 Mo molecular cores spinning with several values of the
ratio of rotational-to-gravitational energies beta=5%-9%. The models include
the indirect gravitational potential caused by disc asymmetries. We find that
this modifies the barycenter of the disc, causing significant excursions of the
central star position, which we term stellar wobbling. The stellar wobbling
slows down and protracts the development of gravitational instability in the
disc, reducing the number and magnitude of the accretion-driven bursts
undergone by the young massive stars, whose properties are in good agreement
with that of the burst monitored from the massive protostar M17 MIR. Including
stellar wobbling is therefore important for accurate modeling disc structures.
Synthetic ALMA interferometric images in the millimeter waveband show that the
outcomes of efficient gravitational instability such as spiral arms and gaseous
clumps can be detected for as long as the disc is old enough and has already
entered the burst mode of accretion.Science and Technology Facilities Council (STFC)Ministry of Science and Higher Education of the Russian FederationEuropean Research Council (ERC)MOS
Profound Effect of Profiling Platform and Normalization Strategy on Detection of Differentially Expressed MicroRNAs â A Comparative Study
Adequate normalization minimizes the effects of systematic technical variations and is a prerequisite for getting meaningful biological changes. However, there is inconsistency about miRNA normalization performances and recommendations. Thus, we investigated the impact of seven different normalization methods (reference gene index, global geometric mean, quantile, invariant selection, loess, loessM, and generalized procrustes analysis) on intra- and inter-platform performance of two distinct and commonly used miRNA profiling platforms.We included data from miRNA profiling analyses derived from a hybridization-based platform (Agilent Technologies) and an RT-qPCR platform (Applied Biosystems). Furthermore, we validated a subset of miRNAs by individual RT-qPCR assays. Our analyses incorporated data from the effect of differentiation and tumor necrosis factor alpha treatment on primary human skeletal muscle cells and a murine skeletal muscle cell line. Distinct normalization methods differed in their impact on (i) standard deviations, (ii) the area under the receiver operating characteristic (ROC) curve, (iii) the similarity of differential expression. Loess, loessM, and quantile analysis were most effective in minimizing standard deviations on the Agilent and TLDA platform. Moreover, loess, loessM, invariant selection and generalized procrustes analysis increased the area under the ROC curve, a measure for the statistical performance of a test. The Jaccard index revealed that inter-platform concordance of differential expression tended to be increased by loess, loessM, quantile, and GPA normalization of AGL and TLDA data as well as RGI normalization of TLDA data.We recommend the application of loess, or loessM, and GPA normalization for miRNA Agilent arrays and qPCR cards as these normalization approaches showed to (i) effectively reduce standard deviations, (ii) increase sensitivity and accuracy of differential miRNA expression detection as well as (iii) increase inter-platform concordance. Results showed the successful adoption of loessM and generalized procrustes analysis to one-color miRNA profiling experiments
Statin use in patients with chronic kidney disease stages 2â4: targeting beyond improved mortality rates
Measurement of D-s(+) and D-s(*+) production in B meson decays and from continuum e(+)e(-) annihilation at âs=10.6 GeV
This is the pre-print version of the Article. The official published version can be accessed from the links below. Copyright @ 2002 APSNew measurements of Ds+ and Ds*+ meson production rates from B decays and from qqÌ
continuum events near the ΄(4S) resonance are presented. Using 20.8 fb-1 of data on the ΄(4S) resonance and 2.6 fb-1 off-resonance, we find the inclusive branching fractions B(BâDs+X)=(10.93±0.19±0.58±2.73)% and B(BâDs*+X)=(7.9±0.8±0.7±2.0)%, where the first error is statistical, the second is systematic, and the third is due to the Ds+âÏÏ+ branching fraction uncertainty. The production cross sections Ï(e+e-âDs+X)ĂB(Ds+âÏÏ+)=7.55±0.20±0.34pb and Ï(e+e-âDs*±X)ĂB(Ds+âÏÏ+)=5.8±0.7±0.5pb are measured at center-of-mass energies about 40 MeV below the ΄(4S) mass. The branching fractions ÎŁB(BâDs(*)+D(*))=(5.07±0.14±0.30±1.27)% and ÎŁB(BâDs*+D(*))=(4.1±0.2±0.4±1.0)% are determined from the Ds(*)+ momentum spectra. The mass difference m(Ds+)-m(D+)=98.4±0.1±0.3MeV/c2 is also measured.This work was supported by DOE and NSF (USA), NSERC (Canada), IHEP (China), CEA and CNRS-IN2P3 (France), BMBF (Germany), INFN (Italy), NFR (Norway), MIST (Russia), and PPARC (United Kingdom). Individuals have received support from the Swiss NSF, A. P. Sloan Foundation, Research Corporation, and Alexander von Humboldt Foundation
Rapid Identification of Bio-Molecules Applied for Detection of Biosecurity Agents Using Rolling Circle Amplification
Detection and identification of pathogens in environmental samples for biosecurity applications are challenging due to the strict requirements on specificity, sensitivity and time. We have developed a concept for quick, specific and sensitive pathogen identification in environmental samples. Target identification is realized by padlock- and proximity probing, and reacted probes are amplified by RCA (rolling-circle amplification). The individual RCA products are labeled by fluorescence and enumerated by an instrument, developed for sensitive and rapid digital analysis. The concept is demonstrated by identification of simili biowarfare agents for bacteria (Escherichia coli and Pantoea agglomerans) and spores (Bacillus atrophaeus) released in field
Measurement of the branching fraction and CP content for the decay B(0) -> D(*+)D(*-)
This is the pre-print version of the Article. The official published version can be accessed from the links below. Copyright @ 2002 APS.We report a measurement of the branching fraction of the decay B0âD*+D*- and of the CP-odd component of its final state using the BABAR detector. With data corresponding to an integrated luminosity of 20.4ââfb-1 collected at the ΄(4S) resonance during 1999â2000, we have reconstructed 38 candidate signal events in the mode B0âD*+D*- with an estimated background of 6.2±0.5 events. From these events, we determine the branching fraction to be B(B0âD*+D*-)=[8.3±1.6(stat)±1.2(syst)]Ă10-4. The measured CP-odd fraction of the final state is 0.22±0.18(stat)±0.03(syst).This work is supported by DOE and NSF (USA), NSERC (Canada), IHEP (China), CEA and CNRS-IN2P3 (France), BMBF (Germany), INFN (Italy), NFR (Norway), MIST (Russia), and PPARC (United Kingdom). Individuals have received support from the A.P. Sloan Foundation, Research Corporation, and Alexander von Humboldt Foundation
Comparison of dynamic monitoring strategies based on CD4 cell counts in virally suppressed, HIV-positive individuals on combination antiretroviral therapy in high-income countries: a prospective, observational study
BACKGROUND:
Clinical guidelines vary with respect to the optimal monitoring frequency of HIV-positive individuals. We compared dynamic monitoring strategies based on time-varying CD4 cell counts in virologically suppressed HIV-positive individuals.
METHODS:
In this observational study, we used data from prospective studies of HIV-positive individuals in Europe (France, Greece, the Netherlands, Spain, Switzerland, and the UK) and North and South America (Brazil, Canada, and the USA) in The HIV-CAUSAL Collaboration and The Centers for AIDS Research Network of Integrated Clinical Systems. We compared three monitoring strategies that differ in the threshold used to measure CD4 cell count and HIV RNA viral load every 3â6 months (when below the threshold) or every 9â12 months (when above the threshold). The strategies were defined by the threshold CD4 counts of 200 cells per ÎŒL, 350 cells per ÎŒL, and 500 cells per ÎŒL. Using inverse probability weighting to adjust for baseline and time-varying confounders, we estimated hazard ratios (HRs) of death and of AIDS-defining illness or death, risk ratios of virological failure, and mean differences in CD4 cell count.
FINDINGS:
47â635 individuals initiated an antiretroviral therapy regimen between Jan 1, 2000, and Jan 9, 2015, and met the eligibility criteria for inclusion in our study. During follow-up, CD4 cell count was measured on average every 4·0 months and viral load every 3·8 months. 464 individuals died (107 in threshold 200 strategy, 157 in threshold 350, and 200 in threshold 500) and 1091 had AIDS-defining illnesses or died (267 in threshold 200 strategy, 365 in threshold 350, and 459 in threshold 500). Compared with threshold 500, the mortality HR was 1·05 (95% CI 0·86â1·29) for threshold 200 and 1·02 (0·91·1·14) for threshold 350. Corresponding estimates for death or AIDS-defining illness were 1·08 (0·95â1·22) for threshold 200 and 1·03 (0·96â1·12) for threshold 350. Compared with threshold 500, the 24 month risk ratios of virological failure (viral load more than 200 copies per mL) were 2·01 (1·17â3·43) for threshold 200 and 1·24 (0·89â1·73) for threshold 350, and 24 month mean CD4 cell count differences were 0·4 (â25·5 to 26·3) cells per ÎŒL for threshold 200 and â3·5 (â16·0 to 8·9) cells per ÎŒL for threshold 350.
INTERPRETATION:
Decreasing monitoring to annually when CD4 count is higher than 200 cells per ÎŒL compared with higher than 500 cells per ÎŒL does not worsen the short-term clinical and immunological outcomes of virally suppressed HIV-positive individuals. However, more frequent virological monitoring might be necessary to reduce the risk of virological failure. Further follow-up studies are needed to establish the long-term safety of these strategies.
FUNDING
National Institutes of Health
Jet energy measurement with the ATLAS detector in proton-proton collisions at root s=7 TeV
The jet energy scale and its systematic uncertainty are determined for jets measured with the ATLAS detector at the LHC in proton-proton collision data at a centre-of-mass energy of âs = 7TeV corresponding to an integrated luminosity of 38 pb-1. Jets are reconstructed with the anti-kt algorithm with distance parameters R=0. 4 or R=0. 6. Jet energy and angle corrections are determined from Monte Carlo simulations to calibrate jets with transverse momenta pTâ„20 GeV and pseudorapidities {pipe}η{pipe}<4. 5. The jet energy systematic uncertainty is estimated using the single isolated hadron response measured in situ and in test-beams, exploiting the transverse momentum balance between central and forward jets in events with dijet topologies and studying systematic variations in Monte Carlo simulations. The jet energy uncertainty is less than 2. 5 % in the central calorimeter region ({pipe}η{pipe}<0. 8) for jets with 60â€pT<800 GeV, and is maximally 14 % for pT<30 GeV in the most forward region 3. 2â€{pipe}η{pipe}<4. 5. The jet energy is validated for jet transverse momenta up to 1 TeV to the level of a few percent using several in situ techniques by comparing a well-known reference such as the recoiling photon pT, the sum of the transverse momenta of tracks associated to the jet, or a system of low-pT jets recoiling against a high-pT jet. More sophisticated jet calibration schemes are presented based on calorimeter cell energy density weighting or hadronic properties of jets, aiming for an improved jet energy resolution and a reduced flavour dependence of the jet response. The systematic uncertainty of the jet energy determined from a combination of in situ techniques is consistent with the one derived from single hadron response measurements over a wide kinematic range. The nominal corrections and uncertainties are derived for isolated jets in an inclusive sample of high-pT jets. Special cases such as event topologies with close-by jets, or selections of samples with an enhanced content of jets originating from light quarks, heavy quarks or gluons are also discussed and the corresponding uncertainties are determined. © 2013 CERN for the benefit of the ATLAS collaboration
Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector
The inclusive and dijet production cross-sections have been measured for jets
containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass
energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The
measurements use data corresponding to an integrated luminosity of 34 pb^-1.
The b-jets are identified using either a lifetime-based method, where secondary
decay vertices of b-hadrons in jets are reconstructed using information from
the tracking detectors, or a muon-based method where the presence of a muon is
used to identify semileptonic decays of b-hadrons inside jets. The inclusive
b-jet cross-section is measured as a function of transverse momentum in the
range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet
cross-section is measured as a function of the dijet invariant mass in the
range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets
and the angular variable chi in two dijet mass regions. The results are
compared with next-to-leading-order QCD predictions. Good agreement is observed
between the measured cross-sections and the predictions obtained using POWHEG +
Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet
cross-section. However, it does not reproduce the measured inclusive
cross-section well, particularly for central b-jets with large transverse
momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final
version published in European Physical Journal
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