5,704 research outputs found
j_psi Suppression and the Quark-Gluon Plasma
All measured Feynman x_f distributions of the ratio, R, of j_psi production
in nuclei relative to production on protons fall off with x_f.
They show [2] that absorption of charmonium cannot be the only source of
j_psi suppression and that energy loss of the constituents of the incident
proton prior to the j_psi production, because of the exponential sqrt(s)
dependence of the charmonium cross section, should not be neglected. Including
the effects of initial state energy loss we find that the latest measured
Pb-Pb j_psi cross sections do not provide any evidence for deconfinement.Comment: 9 pages, 2 figures, additional material, accepted by Physics Letter
Study of Production in GeV and Collisions in PHENIX
measurements in and collisions serve as crucial
references to understand the production in collisions at RHIC
where quark gluon plasma (QGP) is expected to be formed. They also provide
important clues to study various interesting phenomena such as the gluon
shadowing and color glass condensate. We report the latest results from PHENIX
experiment on production in and collisions at forward,
backward and midrapidity.Comment: 4pages, 6 figures, proceeding of the 18th International Conference on
Nucleus-Nucleus Collisions (QM2005), Aug.4-9, Budapest, Hungar
The Future of Hard and Electromagnetic Probes at RHIC
Potential near- and long-term physics opportunities with jets, heavy flavors
and electromagnetic probes at the Relativistic Heavy Ion Collider (RHIC) are
presented. Much new physics remains to be unveiled using these probes, due to
their sensitivity to the initial high density stage of RHIC collisions, when
quark-gluon plasma (QGP) formation is expected. Additional physics will include
addressing deconfinement, chiral symmetry restoration, properties of the
strongly-coupled QGP and a possible weakly-interacting QGP, color glass
condensate in the initial state, and hadronization. To fully realize the
physics prospects of the RHIC energy regime, new detector components must be
added to existing experiments, the RHIC machine luminosity upgraded, and a
possible new detector with significantly extended coverage and capabilities
added.Comment: 6 pages, 3 figures, Hard Probes 2004, International Conference on
Hard and Electromagnetic Probes of High Energy Nuclear Collision
Kakutani Dichotomy on Free States
Two quasi-free states on a CAR or CCR algebra are shown to generate
quasi-equivalent representations unless they are disjoint.Comment: 12 page
Goodness-of-Fit Tests for Symmetric Stable Distributions -- Empirical Characteristic Function Approach
We consider goodness-of-fit tests of symmetric stable distributions based on
weighted integrals of the squared distance between the empirical characteristic
function of the standardized data and the characteristic function of the
standard symmetric stable distribution with the characteristic exponent
estimated from the data. We treat as an unknown parameter,
but for theoretical simplicity we also consider the case that is
fixed. For estimation of parameters and the standardization of data we use
maximum likelihood estimator (MLE) and an equivariant integrated squared error
estimator (EISE) which minimizes the weighted integral. We derive the
asymptotic covariance function of the characteristic function process with
parameters estimated by MLE and EISE. For the case of MLE, the eigenvalues of
the covariance function are numerically evaluated and asymptotic distribution
of the test statistic is obtained using complex integration. Simulation studies
show that the asymptotic distribution of the test statistics is very accurate.
We also present a formula of the asymptotic covariance function of the
characteristic function process with parameters estimated by an efficient
estimator for general distributions
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Risk factors for fecal carriage of drug-resistant Escherichia coli: a systematic review and meta-analysis.
BackgroundAntimicrobial resistance is a serious public health problem. Fecal carriage of drug-resistant bacteria has been suggested as an important source of antimicrobial resistant genes (ARGs). We aimed to identify risk factors associated with fecal carriage of drug-resistant commensal Escherichia coli among healthy adult population.MethodsWe conducted a systematic review and meta-analysis following the PRISMA guideline. We identified observational studies published from 2014 to 2019 through PubMed, Embase, and Web of Science. Studies were eligible if they investigated and reported risk factors and accompanying measure of associations for fecal carriage of drug-resistant E. coli for healthy population aged 18-65. Data on risk factors assessed in three or more studies were extracted.ResultsFifteen of 395 studies involving 11480 healthy individuals were included. The pooled prevalence of drug-resistant Enterobacteriaceae was 14% (95% confidence interval [CI] 8-23%). Antimicrobial use within the 12 months prior to stool culture (odds ratio [OR] 1.84 [95%CI 1.35-2.51]), diarrhea symptoms (OR 1.56 [95%CI 1.09-2.25]), travel to India (OR 4.15 [95%CI 2.54-6.78]), and vegetarian diet (OR 1.60 [95%CI 1.00(1.0043)-2.56(2.5587)]) were associated with increased risk of fecal carriage of drug-resistant E. coli. Among travellers, antimicrobial use (OR 2.81 [95%CI 1.47-5.36]), diarrhea symptoms (OR 1.65 [95%CI 1.02-2.68]), travel to India (OR 3.80 [95%CI 2.23-6.47]), and vegetarian diet (OR 1.92 [95%CI 1.13-3.26]) were associated with increased risk. Among general adult population, antimicrobial use (OR 1.51 [95%CI 1.17-1.94]), diarrhea symptoms (OR 1.53 [95%CI 1.27-1.84]), and travel to Southeast Asia (OR 1.67 [95%CI 1.02-2.73]) were associated with the increased risk of drug-resistant E. coli carriage.ConclusionsThe findings indicate that dietary habit as well as past antimicrobial use and travel to high-risk country are associated with the risk of fecal carriage of drug-resistant commensal E. coli
Machine Learning Mitigants for Speech Based Cyber Risk
Statistical analysis of speech is an emerging area of machine learning. In this paper, we tackle the biometric challenge of Automatic Speaker Verification (ASV) of differentiating between samples generated by two distinct populations of utterances, those of an authentic human voice and those generated by a synthetic one. Solving such an issue through a statistical perspective foresees the definition of a decision rule function and a learning procedure to identify the optimal classifier. Classical state-of-the-art countermeasures rely on strong assumptions such as stationarity or local-stationarity of speech that may be atypical to encounter in practice. We explore in this regard a robust non-linear and non-stationary signal decomposition method known as the Empirical Mode Decomposition combined with the Mel-Frequency Cepstral Coefficients in a novel fashion with a refined classifier technique known as multi-kernel Support Vector machine. We undertake significant real data case studies covering multiple ASV systems using different datasets, including the ASVSpoof 2019 challenge database. The obtained results overwhelmingly demonstrate the significance of our feature extraction and classifier approach versus existing conventional methods in reducing the threat of cyber-attack perpetrated by synthetic voice replication seeking unauthorised access
Elastic Tensor of SrRuO
The six independent elastic constants of SrRuO were determined using
resonant ultrasound spectroscopy on a high-quality single-crystal specimen. The
constants are in excellent agreement with those obtained from pulse-echo
experiments performed on a sample cut from the same ingot. A calculation of the
Debye temperature using the measured constants agrees well with values obtained
from both specific heat and M\"{o}ssbauer measurements.Comment: 4 pages, 2 figures, 2 tables, submitted to PR
Subtle changes in chromatin loop contact propensity are associated with differential gene regulation and expression.
While genetic variation at chromatin loops is relevant for human disease, the relationships between contact propensity (the probability that loci at loops physically interact), genetics, and gene regulation are unclear. We quantitatively interrogate these relationships by comparing Hi-C and molecular phenotype data across cell types and haplotypes. While chromatin loops consistently form across different cell types, they have subtle quantitative differences in contact frequency that are associated with larger changes in gene expression and H3K27ac. For the vast majority of loci with quantitative differences in contact frequency across haplotypes, the changes in magnitude are smaller than those across cell types; however, the proportional relationships between contact propensity, gene expression, and H3K27ac are consistent. These findings suggest that subtle changes in contact propensity have a biologically meaningful role in gene regulation and could be a mechanism by which regulatory genetic variants in loop anchors mediate effects on expression
Quark-Hadron Duality and Parity Violating Asymmetry of Electroweak Reactions in the Delta Region
A dynamical model of electroweak pion production reactions in the Delta(1232)
region has been extended to include the neutral current contributions for
examining the local Quark-Hadron Duality in neutrino-induced reactions and for
investigating how the axial N-Delta form factor can be determined by the parity
violating asymmetry of N(\vec{e},e') reactions. We first show that the recent
data of (e,e') structure functions F_1 and F_2, which exhibit the Quark-Hadron
Duality, are in good agreement with our predictions. For possible future
experimental tests, we then predict that the structure functions F_1, F_2, and
F_3 for (\nu,e) and (\nu,\nu') processes also show the similar Quark-Hadron
Duality. The spin dependent structure functions g_1 and g_2 of (e,e') have also
been calculated from our model. It is found that the local Quark-Hadron Duality
is not seen in the calculated g_1 and g_2, while our results for g_1 and some
polarization observables associated with the exclusive p(\vec{e},e' pi) and
\vec{p}(\vec{e},e' pi) reactions are in reasonably good agreement with the
recent data. In the investigation of parity violating asymmetry A of
N(\vec{e},e') reactions, it is found that the non-resonant contribution is
small at the Delta peak and a measurement of A can be used to distinguish two
previously determined axial N-Delta transition form factors. The predicted
asymmetry A are also compared with the Parton Model predictions for future
experimental investigations of Quark-Hadron Duality.Comment: 28 pages, 19 figures v2; figures and references adde
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