1,945 research outputs found

    Parton Fragmentation within an Identified Jet at NNLL

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    The fragmentation of a light parton i to a jet containing a light energetic hadron h, where the momentum fraction of this hadron as well as the invariant mass of the jet is measured, is described by "fragmenting jet functions". We calculate the one-loop matching coefficients J_{ij} that relate the fragmenting jet functions G_i^h to the standard, unpolarized fragmentation functions D_j^h for quark and gluon jets. We perform this calculation using various IR regulators and show explicitly how the IR divergences cancel in the matching. We derive the relationship between the coefficients J_{ij} and the quark and gluon jet functions. This provides a cross-check of our results. As an application we study the process e+ e- to X pi+ on the Upsilon(4S) resonance where we measure the momentum fraction of the pi+ and restrict to the dijet limit by imposing a cut on thrust T. In our analysis we sum the logarithms of tau=1-T in the cross section to next-to-next-to-leading-logarithmic accuracy (NNLL). We find that including contributions up to NNLL (or NLO) can have a large impact on extracting fragmentation functions from e+ e- to dijet + h.Comment: expanded introduction, typos fixed, journal versio

    Factorization Properties of Soft Graviton Amplitudes

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    We apply recently developed path integral resummation methods to perturbative quantum gravity. In particular, we provide supporting evidence that eikonal graviton amplitudes factorize into hard and soft parts, and confirm a recent hypothesis that soft gravitons are modelled by vacuum expectation values of products of certain Wilson line operators, which differ for massless and massive particles. We also investigate terms which break this factorization, and find that they are subleading with respect to the eikonal amplitude. The results may help in understanding the connections between gravity and gauge theories in more detail, as well as in studying gravitational radiation beyond the eikonal approximation.Comment: 35 pages, 5 figure

    Alcohol-induced retrograde facilitation renders witnesses of crime less suggestible to misinformation

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    RATIONALE: Research has shown that alcohol can have both detrimental and facilitating effects on memory: intoxication can lead to poor memory for information encoded after alcohol consumption (anterograde amnesia) and may improve memory for information encoded before consumption (retrograde facilitation). This study examined whether alcohol consumed after witnessing a crime can render individuals less vulnerable to misleading post-event information (misinformation). METHOD: Participants watched a simulated crime video. Thereafter, one third of participants expected and received alcohol (alcohol group), one third did not expect but received alcohol (reverse placebo), and one third did not expect nor receive alcohol (control). After alcohol consumption, participants were exposed to misinformation embedded in a written narrative about the crime. The following day, participants completed a cued-recall questionnaire about the event. RESULTS: Control participants were more likely to report misinformation compared to the alcohol and reverse placebo group. CONCLUSION: The findings suggest that we may oversimplify the effect alcohol has on suggestibility and that sometimes alcohol can have beneficial effects on eyewitness memory by protecting against misleading post-event information

    PD-1 Regulates Neural Damage in Oligodendroglia-Induced Inflammation

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    We investigated the impact of immune regulatory mechanisms involved in the modulation of the recently presented, CD8+ lymphocyte mediated immune response in a mouse model of oligodendropathy-induced inflammation (PLPtg-mutants). The focus was on the role of the co-inhibitory molecule PD-1, a CD28-related receptor expressed on activated T- and B-lymphocytes associated with immune homeostasis and autoimmunity. PLPtg/PD-1-deficient double mutants and the corresponding bone marrow chimeras were generated and analysed using immunohistochemistry, light- and electron microscopy, with particular emphasis on immune-cell number and neural damage. In addition, the immune cells in both the CNS and the peripheral immune system were investigated by IFN-gamma elispot assays and spectratype analysis. We found that mice with combined pathology exhibited significantly increased numbers of CD4+ and CD8+ T-lymphocytes in the CNS. Lack of PD-1 substantially aggravated the pathological phenotype of the PLPtg mutants compared to genuine PLPtg mutants, whereas the PD-1 deletion alone did not cause alterations in the CNS. CNS T-lymphocytes in PLPtg/PD-1-/- double mutants exhibited massive clonal expansions. Furthermore, PD-1 deficiency was associated with a significantly higher propensity of CNS but not peripheral CD8+ T-cells to secrete proinflammatory cytokines. PD-1 could be identified as a crucial player of tissue homeostasis and immune-mediated damage in a model of oligodendropathy-induced inflammation. Alterations of this regulatory pathway lead to overt neuroinflammation of high pathogenetic impact. Our finding may have implications for understanding the mechanisms leading to the high clinical variability of polygenic or even monogenic disorders of the nervous system

    Five-year outcome in 18 010 patients from the German Aortic Valve Registry

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    OBJECTIVES: To determine the 5-year outcome in patients treated by isolated transcatheter aortic valve implantation (TAVI) or surgical aortic valve replacement (sAVR)—a prospective observational cohort study. METHODS: A total of 18 010 patients were included (n = 8942 TAVI and n = 9068 sAVR) in the German Aortic Valve Registry (GARY) who were treated in 2011 and 2012 at 92 sites in central Germany. Eligible patients with TAVI and sAVR were matched using propensity scores in a nearest-neighbour approach. Patients with repeat procedures or unequivocal indication for one treatment option (e.g. frailty) were excluded (n = 4785 for TAVI and n = 2 for sAVR). This led to 13 223 patients (4157 TAVI and 9066 sAVR) as an unmatched subcohort. The main outcome measure was the 5-year all-cause mortality. RESULTS: TAVI patients were significantly older (80.9 ± 6.1 vs 68.5 ± 11.1 years, P < 0.001), had a higher Society of Thoracic Surgeons (STS) score (6.3 ± 4.9 vs 2.6 ± 3.0, P < 0.001) and a higher 5-year all-cause mortality (49.8% vs 16.5%, P < 0.0001). There was no major difference in in-hospital stroke, in-hospital myocardial infarction, or temporary and chronic dialysis. In the propensity score-matched group (n = 3640), there were 763 deaths (41.9%) among 1820 TAVI patients compared with 552 (30.3%) among 1820 treated with sAVR during the 5-year follow-up (hazard ratio 1.51, 95% confidence interval 1.35–1.68; P < 0.0001). New pacemaker implantation was performed in 448 patients (24.6%) after TAVI and in 201 (11.0%) after sAVR (P < 0.0001). CONCLUSIONS: The 5-year follow-up data show that TAVI patients were significantly older and had a higher STS score than sAVR patients. After propensity score matching, TAVI with early-generation prosthesis was associated with significantly higher 5-year all-cause mortality than sAVR

    Role of the mesoamygdaloid dopamine projection in emotional learning

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    Amygdala dopamine is crucially involved in the acquisition of Pavlovian associations, as measured via conditioned approach to the location of the unconditioned stimulus (US). However, learning begins before skeletomotor output, so this study assessed whether amygdala dopamine is also involved in earlier 'emotional' learning. A variant of the conditioned reinforcement (CR) procedure was validated where training was restricted to curtail the development of selective conditioned approach to the US location, and effects of amygdala dopamine manipulations before training or later CR testing assessed. Experiment 1a presented a light paired (CS+ group) or unpaired (CS- group) with a US. There were 1, 2 or 10 sessions, 4 trials per session. Then, the US was removed, and two novel levers presented. One lever (CR+) presented the light, and lever pressing was recorded. Experiment 1b also included a tone stimulus. Experiment 2 applied intra-amygdala R(+) 7-OH-DPAT (10 nmol/1.0 A mu l/side) before two training sessions (Experiment 2a) or a CR session (Experiment 2b). For Experiments 1a and 1b, the CS+ group preferred the CR+ lever across all sessions. Conditioned alcove approach during 1 or 2 training sessions or associated CR tests was low and nonspecific. In Experiment 2a, R(+) 7-OH-DPAT before training greatly diminished lever pressing during a subsequent CR test, preferentially on the CR+ lever. For Experiment 2b, R(+) 7-OH-DPAT infusions before the CR test also reduced lever pressing. Manipulations of amygdala dopamine impact the earliest stage of learning in which emotional reactions may be most prevalent

    The utility of B-type natriuretic peptide in the diagnosis of heart failure in the emergency department: a systematic review

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    <p>Abstract</p> <p>Background</p> <p>Dyspnea is a common chief complaint in the emergency department (ED); differentiating heart failure (HF) from other causes can be challenging. Brain Natriuretic Peptide (BNP) is a new diagnostic test for HF for use in dyspneic patients in the ED. The purpose of this study is to systematically review the accuracy of BNP in the emergency diagnosis of HF.</p> <p>Methods</p> <p>We searched MEDLINE (1975–2005) supplemented by reference tracking. We included studies that reported the sensitivity and specificity of BNP for diagnosing HF in ED patients with acute dyspnea. Two reviewers independently assessed study quality. We pooled sensitivities and specificities within five ranges of BNP cutoffs.</p> <p>Results</p> <p>Ten studies including 3,344 participants met inclusion criteria. Quality was variable; possible verification or selection bias was common. No studies eliminated patients with obvious medical causes of dyspnea. Most studies used the Triage BNP assay; all utilized a clinical reference standard. Pooled sensitivity and specificity at a BNP cutoff of 100–105 pg/ml were 90% and 74% with negative likelihood ratio (LR) of 0.14; pooled sensitivity was 81% with specificity of 90% at cutoffs between 300 and 400 pg/ml with positive LR of 7.6.</p> <p>Conclusion</p> <p>Our analysis suggests that BNP has moderate accuracy in detecting HF in the ED. Our results suggest utilizing a BNP of less than 100 pg/ml to rule out HF and a BNP of greater than 400 pg/ml to diagnose HF. Many studies were of marginal quality, and all included patients with varying degrees of diagnostic uncertainty. Further studies focusing on patients with diagnostic uncertainty will clarify the real-world utility of BNP in the emergency management of dyspnea.</p

    Cardiac biomarkers of acute coronary syndrome: from history to high-sensitivity cardiac troponin

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    The role of cardiac troponins as diagnostic biomarkers of myocardial injury in the context of acute coronary syndrome (ACS) is well established. Since the initial 1st-generation assays, 5th-generation high-sensitivity cardiac troponin (hs-cTn) assays have been developed, and are now widely used. However, its clinical adoption preceded guidelines and even best practice evidence. This review summarizes the history of cardiac biomarkers with particular emphasis on hs-cTn. We aim to provide insights into using hs-cTn as a quantitative marker of cardiomyocyte injury to help in the differential diagnosis of coronary versus non-coronary cardiac diseases. We also review the recent evidence and guidelines of using hs-cTn in suspected ACS
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