1,960 research outputs found

    Antenna subtraction with hadronic initial states

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    The antenna subtraction method for the computation of higher order corrections to jet observables and exclusive cross sections at collider experiments is extended to include hadronic initial states. In addition to the already known antenna subtraction with both radiators in the final state (final-final antennae), we introduce antenna subtractions with one or two radiators in the initial state (initial-final or initial-initial antennae). For those, we derive the phase space factorization and discuss the allowed phase space mappings at NLO and NNLO. We present integrated forms for all antenna functions relevant to NLO calculations, and describe the construction of the full antenna subtraction terms at NLO on two examples. The extension of the formalism to NNLO is outlined.Comment: 33 pages, 3 figure

    The infrared structure of e+ e- --> 3 jets at NNLO reloaded

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    This paper gives detailed information on the structure of the infrared singularities for the process e+ e- --> 3 jets at next-to-next-to-leading order in perturbation theory. Particular emphasis is put on singularities associated to soft gluons. The knowledge of the singularity structure allows the construction of appropriate subtraction terms, which in turn can be implemented into a numerical Monte Carlo program.Comment: 59 pages, additional comments added, version to be publishe

    A Los Angeles és Duarte galaktóz-1-foszfát-uridil-transzferáz-variánsok allélgyakorisága a magyar populációban

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    Classical galactosaemia is an autosomal recessively inherited disorder caused by deficient activity of the enzyme galactose-1-phosphate uridyltransferase (GALT), which can be detected by newborn screening. The p.N314D mutation defines two variant forms of the GALT enzyme, the Los Angeles and Duarte, depending on the presence of additional base changes. Aim: The aim of our study was to analyze a healthy Hungarian population for the frequencies of the Los Angeles and Duarte galactose-1-phosphate uridyltransferase variant alleles. Methods: DNA samples from 100 subjects were analyzed by polymerase chain reaction, followed by digestion with restriction endonucleases. Results: The frequencies of the p.N314D, the Los Angeles and the Duarte variants were 11.5%, 2.5% and 9%, respectively. Conclusions: The allele frequencies of the Los Angeles and Duarte variant alleles in the Hungarian population correlate well with the allele frequencies in other healthy Caucasian populations

    NMDA receptor content of synapses in stratum radiatum of the hippocampal CA1 area

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    Glutamate receptors activated by NMDA (NMDARs) or AMPA (AMPARs) are clustered on dendritic spines of pyramidal cells. Both the AMPAR-mediated postsynaptic responses and the synaptic AMPAR immunoreactivity show a large intersynapse variability. Postsynaptic responses mediated by NMDARs show less variability. To assess the variability in NMDAR content and the extent of their coexistence with AMPARs in Schaffer collateral-commissural synapses of adult rat CA1 pyramidal cells, electron microscopic immunogold localization of receptors has been used. Immunoreactivity of NMDARs was detected in virtually all synapses on spines, but AMPARs were undetectable, on average, in 12% of synapses. A proportion of synapses had a very high AMPAR content relative to the mean content, resulting in a distribution more skewed toward larger values than that of NMDARs. The variability of synaptic NMDAR content [coefficient of variation (CV), 0.64-0.70] was much lower than that of the AMPAR content (CV, 1.17-1.45). Unlike the AMPAR content, the NMDAR content showed only a weak correlation with synapse size. As reported previously for AMPARs, the immunoreactivity of NMDARs was also associated with the spine apparatus within spines. The results demonstrate that the majority of the synapses made by CA3 pyramidal cells onto spines of CA1 pyramids express both NMDARs and AMPARs, but with variable ratios. A less-variable NMDAR content is accompanied by a wide variability of AMPAR content, indicating that the regulation of expression of the two receptors is not closely linked. These findings support reports that fast excitatory transmission at some of these synapses is mediated by activation mainly of NMDARs

    Can variability in the effect of opioids on refractory breathlessness be explained by genetic factors?

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    © 2015, BMJ Publishing Group. All rights reserved. Objectives: Opioids modulate the perception of breathlessness with a considerable variation in response, with poor correlation between the required opioid dose and symptom severity. The objective of this hypothesis-generating, secondary analysis was to identify candidate single nucleotide polymorphisms (SNP) from those associated with opioid receptors, signalling or pain modulation to identify any related to intensity of breathlessness while on opioids. This can help to inform prospective studies and potentially lead to better tailoring of opioid therapy for refractory breathlessness. Setting: 17 hospice/palliative care services (tertiary services) in 11 European countries. Participants: 2294 people over 18 years of age on regular opioids for pain related to cancer or its treatment. Primary outcome measures: The relationship between morphine dose, breathlessness intensity (European Organisation for Research and Treatment of Cancer Core Quality of Life Questionnaire; EORTCQLQC30 question 8) and 112 candidate SNPs from 25 genes (n=588). Secondary outcome measures: The same measures for people on oxycodone (n=402) or fentanyl (n=429). Results: SNPs not in Hardy-Weinberg equilibrium or with allele frequencies ( < 5%) were removed. Univariate associations between each SNP and breathlessness intensity were determined with Benjamini-Hochberg false discovery rate set at 20%. Multivariable ordinal logistic regression, clustering over country and adjusting for available confounders, was conducted with remaining SNPs. For univariate morphine associations, 1 variant on the 5-hydroxytryptamine type 3B (HTR3B) gene, and 4 on the β-2-arrestin gene (ARRB2) were associated with more intense breathlessness. 1 SNP remained significant in the multivariable model: people with rs7103572 SNP (HTR3B gene; present in 8.4% of the population) were three times more likely to have more intense breathlessness (OR 2.86; 95% CIs 1.46 to 5.62; p=0.002). No associations were seen with fentanyl nor with oxycodone. Conclusions: This large, exploratory study identified 1 biologically plausible SNP that warrants further study in the response of breathlessness to morphine therapy

    The fully differential hadronic production of a Higgs boson via bottom quark fusion at NNLO

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    The fully differential computation of the hadronic production cross section of a Higgs boson via bottom quarks is presented at NNLO in QCD. Several differential distributions with their corresponding scale uncertainties are presented for the 8 TeV LHC. This is the first application of the method of non-linear mappings for NNLO differential calculations at hadron colliders.Comment: 27 pages, 13 figures, 1 lego plo

    Subtraction at NNLO

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    We propose a framework for the implementation of a subtraction formalism at NNLO in QCD, based on an observable- and process-independent cancellation of infrared singularities. As a first simple application, we present the calculation of the contribution to the e+e- dijet cross section proportional to C_F T_RComment: 42 pages Latex; 7 figures included. Modifications to the text, and references added; the results are unchange

    Targets and quantitative distribution of GABAergic synapses in the visual cortex of the cat

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    Abstract The morphology and postsynaptic targets of GABA-containing boutons were determined in the striate cortex of cat, using a postembedding immunocytochemical technique at the electron microscopic level. Two types of terminals, both making symmetrical synaptic contacts, were GABA-positive. The first type (95% of all GABApositive boutons) contained small pleomorphic vesicles, the second type (5%) contained larger ovoid vesicles. Furthermore, 99% of all cortical boutons containing pleomorphic vesicles were GABA positive, and all boutons with pleomorphic vesicles made symmetrical synaptic contacts. These results together with previously published stereological data Colonnier, 1985, 1987) were used to estimate the density of GABA-containing synapses, which is about 48 million/mm3 in the striate cortex. The postsynaptic targets of GABA positive boutons were also identified and the distribution was calculated to be as follows: 58% dendritic shafts, 26.4% dendritic spines, 13.1% somata and 2.5% axon initial segments. A total of 11% of the postsynaptic targets were GABA immunoreactive and therefore originated from GABAergic neurons. The results demonstrate that the majority of GABAergic synapses exert their action on the membrane of dendrites and spines rather than on the somata and axons of neurons

    W boson production at hadron colliders: the lepton charge asymmetry in NNLO QCD

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    We consider the production of W bosons in hadron collisions, and the subsequent leptonic decay W->lnu_l. We study the asymmetry between the rapidity distributions of the charged leptons, and we present its computation up to the next-to-next-to-leading order (NNLO) in QCD perturbation theory. Our calculation includes the dependence on the lepton kinematical cuts that are necessarily applied to select W-> lnu_l events in actual experimental analyses at hadron colliders. We illustrate the main differences between the W and lepton charge asymmetry, and we discuss their physical origin and the effect of the QCD radiative corrections. We show detailed numerical results on the charge asymmetry in ppbar collisions at the Tevatron, and we discuss the comparison with some of the available data. Some illustrative results on the lepton charge asymmetry in pp collisions at LHC energies are presented.Comment: 37 pages, 21 figure
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