443 research outputs found
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.
Electroweak Sudakov Logarithms and Real Gauge-Boson Radiation in the TeV Region
Electroweak radiative corrections give rise to large negative,
double-logarithmically enhanced corrections in the TeV region. These are partly
compensated by real radiation and, moreover, affected by selecting
isospin-noninvariant external states. We investigate the impact of real gauge
boson radiation more quantitatively by considering different restricted final
state configurations. We consider successively a massive abelian gauge theory,
a spontaneously broken SU(2) theory and the electroweak Standard Model. We find
that details of the choice of the phase space cuts, in particular whether a
fraction of collinear and soft radiation is included, have a strong impact on
the relative amount of real and virtual corrections.Comment: 20 pages, 4 figure
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.
Sudakov Electroweak effects in transversely polarized beams
We study Standard Model electroweak radiative corrections for fully inclusive
observables with polarized fermionic beams. Our calculations are relevant in
view of the possibility for Next Generation Linear colliders of having
transversely and/or longitudinally polarized beams. The case of initial
transverse polarization is particularly interesting because of the interplay of
infrared/collinear logarithms of different origins, related both to the
nonabelian SU(2) and abelian U(1) sectors. The Standard model effects turn out
to be in the 10% range at the TeV scale, therefore particularly relevant in
order to disentangle possible New Physics effects.Comment: 5 pages,4 figure
Return-to-activity after anatomical reconstruction of acute high-grade acromioclavicular separation
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
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.http://www.samj.org.zaam2019Paediatrics and Child Healt
Phenolic compounds in young developing kiwifruit in relation to light exposure: Implications for fruit calcium accumulation
The interaction between light availability and the biosynthesis of phenolic compounds in fruit of kiwifruit (Actinidia deliciosa var. deliciosa, C.F. Liang et A. R. Ferguson) was investigated. Fruits were exposed either to natural light or were artificially shaded while growing on mature vines and were analysed weekly during the first 11 weeks of development. Phenols were identified and quantified by using High Performance Liquid Chromatography (HPLC). Results showed that the predominant phenolic compounds were hydroxycinnamic acids (HCAs), flavonols and the flavan 3-ol epicatechin. Calcium (Ca2+), the main mineral nutrient involved in fruit quality was also determined. Light significantly increased the accumulation of both phenols and Ca2+ into the fruit. This work expands the list of known phenolics in kiwifruit and provides a possible explanation for the seasonal pattern of Ca2+ import into the fruit. Results on light–phenol interaction being apparently beneficial for fruit Ca2+ accumulation, suggest that accurate canopy management could enhance fruit quality
Electroweak corrections to W-boson pair production at the LHC
Vector-boson pair production ranks among the most important Standard-Model
benchmark processes at the LHC, not only in view of on-going Higgs analyses.
These processes may also help to gain a deeper understanding of the electroweak
interaction in general, and to test the validity of the Standard Model at
highest energies. In this work, the first calculation of the full one-loop
electroweak corrections to on-shell W-boson pair production at hadron colliders
is presented. We discuss the impact of the corrections on the total cross
section as well as on relevant differential distributions. We observe that
corrections due to photon-induced channels can be amazingly large at energies
accessible at the LHC, while radiation of additional massive vector bosons does
not influence the results significantly.Comment: 29 pages, 15 figures, 4 tables; some references and comments on
\gamma\gamma -> WW added; matches version published in JHE
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