564 research outputs found
Logarithmic electroweak corrections to hadronic Z+1 jet production at large transverse momentum
We consider hadronic production of a Z boson in association with a jet and
study one- and two-loop electroweak logarithmic corrections in the region of
high Z-boson transverse momentum, p_T >> M_Z, including leading and
next-to-leading logarithms. Numerical results for the LHC and Tevatron
colliders are presented. At the LHC these corrections amount to tens of per
cent and will be important for interpretation of the measurements.Comment: 10 pages, 4 figures; one reference added; minor improvements.
Accepted for publication in Phys. Lett.
Innovations in the clinical care of mothers and children in South Africa: The contribution of district clinical specialist teams
The contribution of the District Clinical Specialist Teams (DCSTs) to improving maternal and child health outcomes in South Africa, through strengthening the four pillars of clinical governance, is reflected in innovative work presented at a ‘Promising Practices’ symposium and at various conferences. Of the 24 identified DCST innovations, 21% reflected the clinical effectiveness pillar, 17% clinical risk management, 41% staff development, and 21% user-related considerations. In order to ensure scale-up, the submitted best practices/ innovations were reviewed using the World Health Organization quality standards and ExpandNet parameters for likely scalability. Here we describe one case study from each pillar, illustrating the contribution of the innovations to improved patient outcomes. The development and scale-up of innovations needs to be institutionalised and must include effective support and action from the relevant health managers
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Fluorescence lifetime imaging microscopy (FLIM) to demonstrate the nuclear binding of flavanols and (--epigallocatechin gallate
The use of light microscopy and DMACA staining strongly suggested that plant and animal cell nuclei act as sinks for flavanols [1, 2]. Detailed uv-vis spectroscopic titration experiments indicated that histone proteins are the likely binding sites in the nucleus [2]. Here we report the development of a multi-photon excitation microscopy technique combined with fluorescent lifetime measurements of flavanols. Using this technique, (+) catechin, (-) epicatechin and (-) epigallocatechin gallate (EGCG) showed strikingly different excited state lifetimes in solution. Interaction of histone proteins with flavanols was indicated by the appearance of a significant Ï„2-component of 1.7 to 4.0ns. Tryptophan interference could be circumvented in the in vivo fluorescence lifetime imaging microscopy (FLIM) experiments with 2-photon excitation at 630nm. This enabled visualisation and semi-quantitative measurements that demonstrated unequivocally the absorption of (+)catechin, (-)epicatechin and EGCG by nuclei of onion cells. 3D FLIM revealed for the first time that externally added EGCG penetrated the whole nucleus in onion cells. The relative proportions of EGCG in cytoplasm: nucleus: nucleoli were ca. 1:10:100. FLIM experiments may therefore facilitate probing the health effects of EGCG, which is the major constituent of green tea
Fermionic and Scalar Corrections for the Abelian Form Factor at Two Loops
Two-loop corrections for the form factor in a massive Abelian theory are
evaluated, which result from the insertion of massless fermion or scalar loops
into the massive gauge boson propagator. The result is valid for arbitrary
energies and gauge boson mass. Power-suppressed terms vanish rapidly in the
high energy region where the result is well approximated by a polynomial of
third order in ln(s/M^2). The relative importance of subleading logarithms is
emphasised.Comment: Latex, 10 pages, 5 figures. B. Feucht is B. Jantzen in later
publications. (The contents of the paper is unchanged.
An algorithm for the high-energy expansion of multi-loop diagrams to next-to-leading logarithmic accuracy
We present an algorithm to compute arbitrary multi-loop massive Feynman
diagrams in the region where the typical energy scale \sqrt{s} is much larger
than the typical mass scale M, i.e. s>>M^2, while various different energy and
mass parameters may be present. In this region we perform an asymptotic
expansion and, using sector decomposition, we extract the leading contributions
resulting from ultraviolet and mass singularities, which consist of large
logarithms log(s/M^2) and 1/\epsilon poles in D=4-2\epsilon dimensions. To
next-to-leading accuracy, at L loops all terms of the form \alpha^L
\epsilon^{-k} log^j(s/M^2) with j+k=2L and j+k=2L-1 are taken into account.
This algorithm permits, in particular, to compute higher-order next-to-leading
logarithmic electroweak corrections for processes involving various kinematical
invariants of the order of hundreds of GeV and masses M_W \sim M_Z \sim M_H
\sim M_t of the order of the electroweak scale, in the approximation where the
masses of the light fermions are neglected.Comment: 30 pages, LaTeX. The complete paper is also available via the www at
http://www-ttp.physik.uni-karlsruhe.de/Preprints
Return-to-activity after anatomical reconstruction of acute high-grade acromioclavicular separation
Two-loop electroweak next-to-leading logarithmic corrections to massless fermionic processes
We consider two-loop leading and next-to-leading logarithmic virtual
corrections to arbitrary processes with external massless fermions in the
electroweak Standard Model at energies well above the electroweak scale. Using
the sector-decomposition method and alternatively the strategy of regions we
calculate the mass singularities that arise as logarithms of Q^2/MW^2, where Q
is the energy scale of the considered process, and 1/\epsilon poles in
D=4-2\epsilon dimensions, to one- and two-loop next-to-leading logarithmic
accuracy. The derivations are performed within the complete electroweak theory
with spontaneous symmetry breaking. Our results indicate a close analogy
between the form of two-loop electroweak logarithmic corrections and the
singular structure of scattering amplitudes in massless QCD. We find agreement
with the resummation prescriptions that have been proposed in the literature
based on a symmetric SU(2) \times U(1) theory matched with QED at the
electroweak scale and provide new next-to-leading contributions proportional to
ln(MZ^2/MW^2).Comment: 63 pages, LaTeX, references updated, some typos corrected, version to
appear in Nucl. Phys.
One-loop weak corrections to hadronic production of Z bosons at large transverse momenta
To match the precision of present and future measurements of Z-boson
production at hadron colliders, electroweak radiative corrections must be
included in the theory predictions. In this paper we consider their effect on
the transverse momentum () distribution of Z bosons, with emphasis on
large . We evaluate, analytically and numerically, the full one-loop
corrections for the parton scattering reaction and its
crossed variants. In addition we derive compact approximate expressions which
are valid in the high-energy region, where the weak corrections are strongly
enhanced by logarithms of . These expressions include quadratic
and single logarithms as well as those terms that are not logarithmically
enhanced. This approximation, which confirms and extends earlier results
obtained to next-to-leading logarithmic accuracy, permits to reproduce the
exact one-loop corrections with high precision. Numerical results are presented
for proton-proton and proton-antiproton collisions. The corrections are
negative and their size increases with . For the Tevatron they amount up
to -7% at 300 GeV. For the LHC, where transverse momenta of 2 TeV or more can
be reached, corrections up to -40% are observed. We also include the dominant
two-loop effects of up to 8% in our final LHC predictions.Comment: 32 pages, 7 figure
Return-to-activity after anatomical reconstruction of acute high-grade acromioclavicular separation
BACKGROUND: To evaluate return-to-activity (RtA) after anatomical reconstruction of acute high-grade acromioclavicular joint (ACJ) separation. METHODS: A total of 42 patients with anatomical reconstruction of acute high-grade ACJ-separation (Rockwood Type V) were surveyed to determine RtA at a mean 31 months follow-up (f-u). Sports disciplines, intensity, level of competition, participation in overhead and/or contact sports, as well as activity scales (DASH-Sport-Module, Tegner Activity Scale) were evaluated. Functional outcome evaluation included Constant score and QuickDASH. RESULTS: All patients (42/42) participated in sporting activities at f-u. Neither participation in overhead/contact sports, nor level of activity declined significantly (n.s.). 62 % (n = 26) of patients reported subjective sports specific ACJ integrity to be at least the same as prior to the trauma. Sporting intensity (hours/week: 7.3 h to 5.4 h, p = .004) and level of competition (p = .02) were reduced. If activity changed, in 50 % other reasons but clinical symptoms/impairment were named for modified behavior. QuickDASH (mean 6, range 0–54, SD 11) and DASH-Sport-Module (mean 6, range 0–56, SD 13) revealed only minor disabilities at f-u. Over time Constant score improved significant to an excellent score (mean 94, range 86–100, SD 4; p < .001). Functional outcome was not correlated with RtA (n.s.). CONCLUSION: All patients participated in sporting activities after anatomical reconstruction of high-grade (Rockwood Type V) ACJ-separation. With a high functional outcome there was no significant change in activity level (Tegner) and participation in overhead and/or contact sports observed. There was no correlation between functional outcome and RtA. Limiting, there were alterations in time spent for sporting activities and level of competition observed. But in 50 % those were not related to ACJ symptoms/impairment. Unrelated to successful re-established integrity and function of the ACJ it should be considered that patients decided not return-to-activity but are very content with the procedure
Differential functional benefits of ultra highfield MR systems within the language network
Several investigations have shown limitations of fMRI reliability with the current standard field strengths. Improvement is expected from ultra highfield systems but studies on possible benefits for cognitive networks are lacking. Here we provide an initial investigation on a prominent and clinically highly-relevant cognitive function: language processing in individual brains. 26 patients evaluated for presurgical language localization were investigated with a standardized overt language fMRI paradigm on both 3T and 7T MR scanners. During data acquisition and analysis we made particular efforts to minimize effects not related to static magnetic field strength differences. Six measures relevant for functional activation showed a large dissociation between essential language network nodes: although in Wernicke's area 5/6 measures indicated a benefit of ultra highfield, in Broca's area no comparison was significant. The most important reason for this discrepancy was identified as being an increase in susceptibility-related artifacts in inferior frontal brain areas at ultra high field. We conclude that functional UHF benefits are evident, however these depend crucially on the brain region investigated and the ability to control local artifacts
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