1,525 research outputs found
Computational interpretations of analysis via products of selection functions
We show that the computational interpretation of full comprehension via two wellknown functional interpretations (dialectica and modified realizability) corresponds to two closely related infinite products of selection functions
Soft gluons and superleading logarithms in QCD
After a brief introduction to the physics of soft gluons in QCD we present a
surprising prediction. Dijet production in hadron-hadron collisions provides
the paradigm, i.e. h_1 +h_2 \to jj+X. In particular, we look at the case where
there is a restriction placed on the emission of any further jets in the region
in between the primary (highest p_T) dijets. Logarithms in the ratio of the jet
scale to the veto scale can be summed to all orders in the strong coupling.
Surprisingly, factorization of collinear emissions fails at scales above the
veto scale and triggers the appearance of double logarithms in the hard
sub-process. The effect appears first at fourth order relative to the leading
order prediction and is subleading in the number of colours.Comment: Talk presented at the workshop "New Trends in HERA Physics", Ringberg
Castle, Tegernsee, 5-10 October 200
R-044. Limiting the number of embryos transferred does not significantly influence the outcome of conventional IVF treatment
R-044. Limiting the number of embryos transferred does not significantly influence the outcome of conventional IVF treatment
SEB 1104 TECHNICAL DRG.- 14 D SEP (2
Capability of mechanical alloying and SPS technique to develop nanostructured high Cr, Al alloyed ODS steels
This paper is part of a special issue on High strength ODS steels: fundamentals and propertiesOxide dispersion strengthened (ODS) Fe alloys were produced by mechanical alloying (MA) with the aim of developing a nanostructured powder. The milled powders were consolidated by spark plasma sintering (SPS). Two prealloyed high chromium stainless steels (Fe-14Cr-5Al-3W) and (Fe-20Cr-5Alz3W) with additions of Y2O3 and Ti powders are densified to evaluate the influence of the powder composition on mechanical properties. The microstructure was characterised by scanning electron microscope (SEM) and electron backscattering diffraction (EBSD) was used to analyse grain orientation, grain boundary geometries and distribution grain size. Transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) equipped with energy dispersive X-ray spectrometer (EDX) were used to observe the nanostructure of ODS alloys and especially to observe and analyse the nanoprecipitates. Vickers microhardness and tensile tests (in situ and ex situ) have been performed on the ODS alloys developed in this work.This investigation has been supported by the Ministerio de Ciencia e Innovación de España through the Project ENE2009-13766-C04-03. The authors would like tothank the Dr Fabrice Gaslain for its contribution duringthe of EBSD analysis
Point-of-care C-reactive protein testing in Febrile Children in General Practice
__Background:__ Point-of-care testing for C-reactive protein (CRP) may be helpful in differentiating viral from bacterial infection. Such a device should give results comparable to laboratory testing. The aim was to evaluate two point-of-care CRP tests (Nycocard and QuikRead) in febrile children in general practice, compared to a reference immunoturbidimetric assay.
__Methods:__ Cross-sectional study of febrile children aged 3 months to 6 years presented to a general practice out-of-hours service. Children were visited at home, where blood was taken for the tests, within 24 hours of presentation. The Nycocard test was performed at home, whereas the QuikRead and reference test were performed in the laboratory.
__Results:__ 76 children were enrolled. All three CRP tests were performed in 59 children. The mean difference between the reference test and Nycocard and QuikRead was 0.6 mg/L and –6.1 mg/L, respectively. The slopes of the Passing and Bablok regression were 0.95 (95% CI 0.9-1.0) and 0.83 (95% CI 0.81-0.85) for Nycocard and QuikRead, respectively.
__Conclusion:__ Up to a concentration of 160 mg/L the Nycocard correlated well with the reference test, while the QuikRead underestimated concentrations above 60 mg/L. The Nycocard test seems a good candidate for CRP point-of-care testing in general practice
How much energy do closed timelike curves in 2+1 spacetimes need?
By noticing that, in open 2+1 gravity, polarized surfaces cannot converge in
the presence of timelike total energy momentum (except for a rotation of 2 pi),
we give a simple argument which shows that, quite generally, closed timelike
curves cannot exist in the presence of such energy condition.Comment: 3 pages, with no figures. Accepted in PRD as Rapid Communicatio
Improving mobility performance in wheelchair basketball
Objective: This study aimed to investigate which characteristics of athlete, wheelchair and athlete-wheelchair interface are the best predictors of wheelchair basketball mobility performance. Design: A total of 60 experienced wheelchair basketball players performed a wheelchair mobility performance test to assess their mobility performance. To determine which variables were the best predictors of mobility performance, forward stepwise linear regression analyses were performed on a set of 33 characteristics, including 10 athlete, 19 wheelchair, and 4 athlete-wheelchair interface characteristics. Results: A total of 8 of the characteristics turned out to be significant predictors of wheelchair basketball mobility performance. Classification, experience, maximal isometric force, wheel axis height, and hand rim diameter-which both are interchangeable with each other and wheel diameter-camber angle, and the vertical distance between shoulder and rear wheel axis-which was interchangeable with seat height-were positively associated with mobility performance. The vertical distance between the front seat and the footrest was negatively associated with mobility performance. Conclusion: With this insight, coaches and biomechanical specialists are provided with statistical findings to determine which characteristics they could focus on best to improve mobility performance. Six out of 8 predictors are modifiable and can be optimized to improve mobility performance. These adjustments could be carried out both in training (maximal isometric force) and in wheelchair configurations (eg, camber angle)
Observation of prompt single muons and of missing energy associated with pairs produced in hadronic interactions
In a study of interactions of 400 GeV protons in a totally absorbing iron calorimeter the authors report two observations indicating the hadronic production of heavy short-lived weakly decaying particles. First they have observed a prompt muon signal in the region .8<p/sub t /<2.5 GeV/c. The rate is comparable in magnitude to the prompt 2 mu rate in the same kinematic region. In addition to detecting mu /sup +/ mu /sup -/ events arising from electromagnetic sources (e.g. rho to mu /sup +/ mu /sup -/, psi to mu /sup +/ mu /sup -/ etc.) they have observed mu /sup +/ mu /sup -/ pairs associated with a significant amount of missing energy indicative of final state neutrinos. Interpreting these data as production of DD pairs followed by single or double muonic decays leads to a model dependent estimate of total production cross-section of order 15 mu b. (14 refs)
Generalized unitarity at work: first NLO QCD results for hadronic W+3jet production
We compute the leading color, next-to-leading order QCD corrections to the
dominant partonic channels for the production of a W boson in association with
three jets at the Tevatron and the LHC. This is the first application of
generalized unitarity for realistic one-loop calculations. The method performs
well in this non-trivial test and offers great promise for the future.Comment: 20 pages, 4 figure
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