379 research outputs found

    On Higgs-exchange DIS, physical evolution kernels and fourth-order splitting functions at large x

    Full text link
    We present the coefficient functions for deep-inelastic scattering (DIS) via the exchange of a scalar phi directly coupling only to gluons, such as the Higgs boson in the limit of a very heavy top quark and n_f effectively massless light flavours, to the third order in perturbative QCD. The two-loop results are employed to construct the next-to-next-to-leading order physical evolution kernels for the system (F_2 F_phi) of flavour-singlet structure functions. The practical relevance of these kernels as an alternative to MSbar factorization is bedevilled by artificial double logarithms at small values of the scaling variable x, where the large top-mass limit ceases to be appropriate. However, they show an only single-logarithmic enhancement at large x. Conjecturing that this feature persists to the next order also in the present singlet case, the three-loop coefficient functions facilitate exact predictions (backed up by their particular colour structure) of the double-logarithmic contributions to the fourth-order singlet splitting functions, i.e., of the terms (1-x)^a ln^k(1-x) with k = 4, 5, 6 and k = 3, 4, 5, respectively, for the off-diagonal and diagonal quantities to all powers a in 1-x.Comment: 75 pages, LaTeX, 13 figures (.eps). FORM and Fortran files of main results appended to sourc

    Диагностика патриотической культуры студентов

    Get PDF
    В статье раскрываются основные структурные компоненты патриотической культуры личности: гностический, мотивационный, эмоционально-волевой, поведенческий и нормативно-оценочный. Описывается алгоритм измерения сформированности патриотической культуры личности на основе шкалы суждений. Для обработки результатов опроса использован шкалограммный анализ Л. Гутмана

    Alcohol gel ingestion amongst homeless Eastern and Central Europeans in London: assessing the effects on cognitive functioning and psychological health

    Get PDF
    Background: Intentional consumption of alcohol based hand gels has been reported especially amongst non-UK national, alcohol dependent, homeless individuals in London. Whilst alcohol misuse is known to be associated with impaired cognitive functioning and mental health problems, the effects of additional ingestion of alcohol gel are unknown. Objectives: To explore cognitive and psychological functioning in users who intentionally ingest alcohol gel compared with ethyl-alcohol only misusers and controls. Methods: Male, Central and Eastern European alcohol only misusers, (n=14; mean age 39 years), alcohol gel users (n=14; mean age 43 years) and controls (n=12; mean age 31 years) were recruited from a London Homeless Service during 2013/14. Alcohol misusers, alcohol gel users and controls were compared on the Forwards and Backwards Digit Span Test; Block Design test; Retrospective and Prospective Memory Questionnaire (PRMQ) and the Hospital and Anxiety Depression Scale (HADS). Results: Alcohol gel users performed significantly worse on the Block Design task (p<0.01) and PRMQ (p<0.01) relative to both alcohol only and control groups, and significantly worse on the digit span relative to controls (p=0.01). Both alcohol misusing groups scored comparatively on digit span backwards (p<0.01), with both groups performing significantly worse than controls. The alcohol gel group reported significantly higher levels of anxiety relative to controls (p=0.02). Conclusions: Whilst there could be constitutional differences between alcohol misusers who additionally abuse alcohol gel, the findings suggest that alcohol gel ingestion may have a greater impact on psychological functioning than traditional alcohol misuse

    On next-to-eikonal exponentiation

    Full text link
    The eikonal approximation is at the heart of many theoretical and phenomenological studies involving multiple soft gauge boson emissions in high energy physics. We describe our efforts towards the extension of the eikonal approximation for scattering amplitudes to the first subleading power in the soft momentum.Comment: Proc. of "Loops and Legs in Quantum Field Theory", April, 2010, W\"orlitz, German

    Midday measurements of leaf water potential and stomatal conductance are highly correlated with daily water use of Thompson Seedless grapevines

    Get PDF
    A study was conducted to determine the relationship between midday measurements of vine water status and daily water use of grapevines measured with a weighing lysimeter. Water applications to the vines were terminated on August 24th for 9 days and again on September 14th for 22 days. Daily water use of the vines in the lysimeter (ETLYS) was approximately 40 L vine−1 (5.3 mm) prior to turning the pump off, and it decreased to 22.3 L vine−1 by September 2nd. Pre-dawn leaf water potential (ΨPD) and midday Ψl on August 24th were −0.075 and −0.76 MPa, respectively, with midday Ψl decreasing to −1.28 MPa on September 2nd. Leaf g s decreased from ~500 to ~200 mmol m−2 s−1 during the two dry-down periods. Midday measurements of g s and Ψl were significantly correlated with one another (r = 0.96) and both with ETLYS/ETo (r = ~0.9). The decreases in Ψl, g s, and ETLYS/ETo in this study were also a linear function of the decrease in volumetric soil water content. The results indicate that even modest water stress can greatly reduce grapevine water use and that short-term measures of vine water status taken at midday are a reflection of daily grapevine water us

    Next-to-eikonal corrections to soft gluon radiation: a diagrammatic approach

    Get PDF
    We consider the problem of soft gluon resummation for gauge theory amplitudes and cross sections, at next-to-eikonal order, using a Feynman diagram approach. At the amplitude level, we prove exponentiation for the set of factorizable contributions, and construct effective Feynman rules which can be used to compute next-to-eikonal emissions directly in the logarithm of the amplitude, finding agreement with earlier results obtained using path-integral methods. For cross sections, we also consider sub-eikonal corrections to the phase space for multiple soft-gluon emissions, which contribute to next-to-eikonal logarithms. To clarify the discussion, we examine a class of log(1 - x) terms in the Drell-Yan cross-section up to two loops. Our results are the first steps towards a systematic generalization of threshold resummations to next-to-leading power in the threshold expansion.Comment: 66 pages, 19 figure

    Increasing survival after admission to UK critical care units following cardiopulmonary resuscitation

    Get PDF
    © 2016 The Author(s). Background: In recent years there have been many developments in post-resuscitation care. We have investigated trends in patient characteristics and outcome following admission to UK critical care units following cardiopulmonary resuscitation (CPR) for the period 2004-2014. Our hypothesis is that there has been a reduction in risk-adjusted mortality during this period. Methods: We undertook a prospectively defined, retrospective analysis of the Intensive Care National Audit & Research Centre (ICNARC) Case Mix Programme Database (CMPD) for the period 1 January 2004 to 31 December 2014. Admissions, mechanically ventilated in the first 24 hours in the critical care unit and admitted following CPR, defined as the delivery of chest compressions in the 24 hours before admission, were identified. Case mix, withdrawal, outcome and activity were described annually for all admissions identified as post-cardiac arrest admissions, and separately for out-of-hospital cardiac arrest and in-hospital cardiac arrest. To assess whether in-hospital mortality had improved over time, hierarchical multivariate logistic regression models were constructed, with in-hospital mortality as the dependent variable, year of admission as the main exposure variable and intensive care unit (ICU) as a random effect. All analyses were repeated using only the data from those ICUs contributing data throughout the study period. Results: During the period 2004-2014 survivors of cardiac arrest accounted for an increasing proportion of mechanically ventilated admissions to ICUs in the ICNARC CMPD (9.0 % in 2004 increasing to 12.2 % in 2014). Risk-adjusted hospital mortality following admission to ICU after cardiac arrest has decreased significantly during this period (OR 0.96 per year). Over this time, the ICU length of stay and time to treatment withdrawal has increased significantly. Re-analysis including only those 116 ICUs contributing data throughout the study period confirmed all the results of the primary analysis. Conclusions: Risk-adjusted hospital mortality following admission to ICU after cardiac arrest has decreased significantly during the period 2004-2014. Over the same period the ICU length of stay and time to treatment withdrawal has increased significantly

    Comparison of the i-gel with the cuffed tracheal tube during pressure-controlled ventilation

    Get PDF
    Background. The i-gel (Intersurgical Ltd) is a novel device that differs from other supraglottic airway devices in that it has a softer and a non-inflatable cuff. Our study was designed to assess whether the i-gel is suitable to provide pressure-controlled ventilation (PCV) during anaesthesia by measuring the gas leaks and comparing these values with that of the tracheal tube. Methods. Twenty-five patients, ASA I–II, were recruited to the study. Patients received a standard anaesthetic technique followed by an initial placement of the i-gel. The lungs were then ventilated at three different pressures (15, 20, 25 cm H2O) using PCV. The difference between the inspired and expired tidal volumes was used to calculate the leak volume. The leak fraction was defined as the leak volume divided by the inspired tidal volume. Following these observations, the i-gel was removed and replaced with the conventional tracheal tube and the recordings repeated. Results. There was no significant difference between the leak fractions of the i-gel and the tracheal tube at 15 and 20 cm H2O PCV. At 25 cm H2O, the median difference in leak fraction was 0.02 (P¼0.014) and the median difference in leak volume was 26.5 ml (P¼0.006). There was no evidence of gastric insufflations with any of the pressures used during PCV. Conclusions. We suggest that the i-gel can be used as a reasonable alternative to tracheal tube during PCV with moderate airway pressures. Br J Anaesth 2009; 102: 264–8 Keywords: equipment, airway; ventilation, mechanical Accepted for publication: November 4, 200

    Factorization Properties of Soft Graviton Amplitudes

    Full text link
    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
    corecore