2,409 research outputs found

    Anisotropic expansion of a thermal dipolar Bose gas

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    We report on the anisotropic expansion of ultracold bosonic dysprosium gases at temperatures above quantum degeneracy and develop a quantitative theory to describe this behavior. The theory expresses the post-expansion aspect ratio in terms of temperature and microscopic collisional properties by incorporating Hartree-Fock mean-field interactions, hydrodynamic effects, and Bose-enhancement factors. Our results extend the utility of expansion imaging by providing accurate thermometry for dipolar thermal Bose gases, reducing error in expansion thermometry from tens of percent to only a few percent. Furthermore, we present a simple method to determine scattering lengths in dipolar gases, including near a Feshbach resonance, through observation of thermal gas expansion.Comment: main text and supplement, 11 pages total, 4 figure

    External applicability of the Effect of ticagrelor on Health Outcomes in diabEtes Mellitus patients Intervention Study (THEMIS) trial: An analysis of patients with diabetes and coronary artery disease in the REduction of Atherothrombosis for Continued Health (REACH) registry.

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    THEMIS is a double-blind, randomized trial of 19,220 patients with diabetes mellitus and stable coronary artery disease (CAD) comparing ticagrelor to placebo, in addition to aspirin. The present study aimed to describe the proportion of patients eligible and reasons for ineligibility for THEMIS within a population of patients with diabetes and CAD included in the Reduction of Atherothrombosis for Continued Health (REACH) registry. The THEMIS eligibility criteria were applied to REACH patients. THEMIS included patients ≥50 years with type 2 diabetes and stable CAD as determined by either a history of previous percutaneous coronary intervention, coronary artery bypass grafting, or documentation of angiographic stenosis of ≥50% of at least one coronary artery. Patients with prior myocardial infarction or stroke were excluded. In REACH, 10,156 patients had stable CAD and diabetes. Of these, 6515 (64.1%) patients had at least one exclusion criteria. From the remaining population, 784 patients did not meet inclusion criteria (7.7%) mainly due to absence of aspirin treatment (7.2%), yielding a 'THEMIS-eligible population' of 2857 patients (28.1% of patients with diabetes and stable CAD). The main reasons for exclusion were a history of myocardial infarction (53.1%), use of oral anticoagulation (14.5%), or history of stroke (12.9%). Among the 4208 patients with diabetes and a previous PCI, 1196 patients (28.4%) were eligible for inclusion in the THEMIS-PCI substudy. In a population of patients with diabetes and stable coronary artery disease, a sizeable proportion appear to be 'THEMIS eligible.' http://www. gov identifier: NCT01991795.The THEMIS trial was funded by AstraZeneca. The REACH registry was sponsored by Sanofi, Bristol-Myers Squibb, and the Waksman Foundation (Tokyo, Japan) and is endorsed by the World Heart Federation.S

    Large introns in relation to alternative splicing and gene evolution: a case study of Drosophila bruno-3

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    Background: Alternative splicing (AS) of maturing mRNA can generate structurally and functionally distinct transcripts from the same gene. Recent bioinformatic analyses of available genome databases inferred a positive correlation between intron length and AS. To study the interplay between intron length and AS empirically and in more detail, we analyzed the diversity of alternatively spliced transcripts (ASTs) in the Drosophila RNA-binding Bruno-3 (Bru-3) gene. This gene was known to encode thirteen exons separated by introns of diverse sizes, ranging from 71 to 41,973 nucleotides in D. melanogaster. Although Bru-3's structure is expected to be conducive to AS, only two ASTs of this gene were previously described. Results: Cloning of RT-PCR products of the entire ORF from four species representing three diverged Drosophila lineages provided an evolutionary perspective, high sensitivity, and long-range contiguity of splice choices currently unattainable by high-throughput methods. Consequently, we identified three new exons, a new exon fragment and thirty-three previously unknown ASTs of Bru-3. All exon-skipping events in the gene were mapped to the exons surrounded by introns of at least 800 nucleotides, whereas exons split by introns of less than 250 nucleotides were always spliced contiguously in mRNA. Cases of exon loss and creation during Bru-3 evolution in Drosophila were also localized within large introns. Notably, we identified a true de novo exon gain: exon 8 was created along the lineage of the obscura group from intronic sequence between cryptic splice sites conserved among all Drosophila species surveyed. Exon 8 was included in mature mRNA by the species representing all the major branches of the obscura group. To our knowledge, the origin of exon 8 is the first documented case of exonization of intronic sequence outside vertebrates. Conclusion: We found that large introns can promote AS via exon-skipping and exon turnover during evolution likely due to frequent errors in their removal from maturing mRNA. Large introns could be a reservoir of genetic diversity, because they have a greater number of mutable sites than short introns. Taken together, gene structure can constrain and/or promote gene evolution

    Analysis of Transposon Interruptions Suggests Selection for L1 Elements on the X Chromosome

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    It has been hypothesised that the massive accumulation of L1 transposable elements on the X chromosome is due to their function in X inactivation, and that the accumulation of Alu elements near genes is adaptive. We tested the possible selective advantage of these two transposable element (TE) families with a novel method, interruption analysis. In mammalian genomes, a large number of TEs interrupt other TEs due to the high overall abundance and age of repeats, and these interruptions can be used to test whether TEs are selectively neutral. Interruptions of TEs, which are beneficial for the host, are expected to be deleterious and underrepresented compared with neutral ones. We found that L1 elements in the regions of the X chromosome that contain the majority of the inactivated genes are significantly less frequently interrupted than on the autosomes, while L1s near genes that escape inactivation are interrupted with higher frequency, supporting the hypothesis that L1s on the X chromosome play a role in its inactivation. In addition, we show that TEs are less frequently interrupted in introns than in intergenic regions, probably due to selection against the expansion of introns, but the insertion pattern of Alus is comparable to other repeats

    Disappearance of back-to-back high pTp_T hadron correlations in central Au+Au collisions at sNN\sqrt{s_{NN}} = 200 GeV

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    Azimuthal correlations for large transverse momentum charged hadrons have been measured over a wide pseudo-rapidity range and full azimuth in Au+Au and p+p collisions at sNN\sqrt{s_{NN}} = 200 GeV. The small-angle correlations observed in p+p collisions and at all centralities of Au+Au collisions are characteristic of hard-scattering processes already observed in elementary collisions. A strong back-to-back correlation exists for p+p and peripheral Au + Au. In contrast, the back-to-back correlations are reduced considerably in the most central Au+Au collisions, indicating substantial interaction as the hard-scattered partons or their fragmentation products traverse the medium.Comment: submitted to Phys. Rev. Let

    Particle-type dependence of azimuthal anisotropy and nuclear modification of particle production in Au+Au collisions at s(NN)**(1/2) = 200-GeV

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    We present STAR measurements of the azimuthal anisotropy parameter v2v_2 and the binary-collision scaled centrality ratio RCPR_{CP} for kaons and lambdas (Λ+Λˉ\Lambda+\bar{\Lambda}) at mid-rapidity in Au+Au collisions at sNN=200\sqrt{s_{_{NN}}}=200 GeV. In combination, the v2v_2 and RCPR_{CP} particle-type dependencies contradict expectations from partonic energy loss followed by standard fragmentation in vacuum. We establish pT5p_T \approx 5 GeV/c as the value where the centrality dependent baryon enhancement ends. The KS0K_S^0 and Λ+Λˉ\Lambda+\bar{\Lambda} v2v_2 values are consistent with expectations of constituent-quark-number scaling from models of hadron fromation by parton coalescence or recombination.Comment: 6 pages, 4 figures, 1 table. As published in PRL on Feb. 2, 2004; Significant revisions have been made to the text and color has been added to plot

    Experimental and Theoretical Challenges in the Search for the Quark Gluon Plasma: The STAR Collaboration's Critical Assessment of the Evidence from RHIC Collisions

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    We review the most important experimental results from the first three years of nucleus-nucleus collision studies at RHIC, with emphasis on results from the STAR experiment, and we assess their interpretation and comparison to theory. The theory-experiment comparison suggests that central Au+Au collisions at RHIC produce dense, rapidly thermalizing matter characterized by: (1) initial energy densities above the critical values predicted by lattice QCD for establishment of a Quark-Gluon Plasma (QGP); (2) nearly ideal fluid flow, marked by constituent interactions of very short mean free path, established most probably at a stage preceding hadron formation; and (3) opacity to jets. Many of the observations are consistent with models incorporating QGP formation in the early collision stages, and have not found ready explanation in a hadronic framework. However, the measurements themselves do not yet establish unequivocal evidence for a transition to this new form of matter. The theoretical treatment of the collision evolution, despite impressive successes, invokes a suite of distinct models, degrees of freedom and assumptions of as yet unknown quantitative consequence. We pose a set of important open questions, and suggest additional measurements, at least some of which should be addressed in order to establish a compelling basis to conclude definitively that thermalized, deconfined quark-gluon matter has been produced at RHIC.Comment: 101 pages, 37 figures; revised version to Nucl. Phys.

    Search for direct stau production in events with two hadronic tau-leptons in root s=13 TeV pp collisions with the ATLAS detector

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    A search for the direct production of the supersymmetric partners ofτ-leptons (staus) in final stateswith two hadronically decayingτ-leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of139fb−1, recorded with the ATLAS detector at the LargeHadron Collider at a center-of-mass energy of 13 TeV. No significant deviation from the expected StandardModel background is observed. Limits are derived in scenarios of direct production of stau pairs with eachstau decaying into the stable lightest neutralino and oneτ-lepton in simplified models where the two staumass eigenstates are degenerate. Stau masses from 120 GeV to 390 GeV are excluded at 95% confidencelevel for a massless lightest neutralino
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