Two-Loop Sudakov Form Factor in a Theory with Mass Gap

The two-loop Sudakov form factor is computed in a U(1) model with a massive gauge boson and a $U(1)\times U(1)$ model with mass gap. We analyze the result in the context of hard and infrared evolution equations and establish a matching procedure which relates the theories with and without mass gap setting the stage for the complete calculation of the dominant two-loop corrections to electroweak processes at high energy.Comment: Latex, 5 pages, 2 figures. Bernd Feucht is Bernd Jantzen in later publications. (The contents of the paper is unchanged.

Impact of humoral alloreactivity early after transplantation on the long-term survival of renal allografts

Impact of humoral alloreactivity early after transplantation on the long-term survival of renal allografts.BackgroundThe contribution of humoral alloreactivity to the rejection of renal allografts is not well defined because humoral antigraft reactions are not easily detectable in transplant biopsies, and serial measurements of circulating allo-antibodies in the post-transplantation period are not routinely performed. We have developed diagnostic techniques that improve the assessment of humoral alloreactivity in vivo and in vitro.MethodsHumoral alloreactivity in transplant biopsies derived from 218 single kidney grafts was detected by assessing the deposition of complement fragment C4d in interstitial capillaries. Circulating alloantibodies were determined in corresponding serum samples by flow cytometry using lymphoblastoid cell lines of donor DR-type as target cells and by a conventional microcytotoxicity test. The impact of capillary C4d and other selected variables on renal graft survival was calculated by univariate and multivariate analysis.ResultsCapillary C4d, present in 46% of biopsies from first grafts and 72% of regrafts, is related to circulating alloantibodies. Grafts with capillary C4d have a markedly shorter survival than grafts without capillary C4d (50% graft survival, 4 vs. 8 years, P = 0.0001). Among several risk factors, capillary C4d is the strongest predictor of subsequent graft loss in a multivariate analysis (relative risk, 2.1, 95% CI, 1.4 to 3.1). Humoral alloreactivity detectable within six months after transplantation has a much stronger impact on graft survival than alloreactivity detected beyond this period.ConclusionsHumoral alloreactivity, manifested by the capillary deposition of complement C4d in about 50% of biopsied renal grafts, exerts a strong impact on graft survival when it operates within six months after transplantation

The Two Loop Crossed Ladder Vertex Diagram with Two Massive Exchanges

We compute the (three) master integrals for the crossed ladder diagram with two exchanged quanta of equal mass. The differential equations obeyed by the master integrals are used to generate power series expansions centered around all the singular (plus some regular) points, which are then matched numerically with high accuracy. The expansions allow a fast and precise numerical calculation of the three master integrals (better than 15 digits with less than 30 terms in the whole real axis). A conspicuous relation with the equal-mass sunrise in two dimensions is found. Comparison with a previous large momentum expansion is made finding complete agreement.Comment: 42 pages, 1 figur

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

Taking kangaroo mother care forward in South Africa : the role of district clinical specialist teams

The global agenda for improved neonatal care includes the scale-up of kangaroo mother care (KMC) services. The establishment of district clinical specialist teams (DCSTs) in South Africa (SA) provides an excellent opportunity to enhance neonatal care at district level and ensure translation of policies, including the requirement for KMC implementation, into everyday clinical practice. Tshwane District in Gauteng Province, SA, has been experiencing an increasing strain on obstetric and neonatal services at central, tertiary and regional hospitals in recent years as a result of growing population numbers and rapid up-referral of patients, with limited down-referral of low-risk patients to district-level services. We describe a successful multidisciplinary quality improvement initiative under the leadership of the Tshwane DCST, in conjunction with experienced local KMC implementers, aimed at expanding the district’s KMC services. The project subsequently served as a platform for improvement of other areas of neonatal care by means of a systematic approach.http://www.samj.org.zaam2016Paediatrics and Child Healt

The impact of health programmes to prevent vertical transmission of HIV. Advances, emerging health challenges and research priorities for children exposed to or living with HIV: Perspectives from South Africa

Over the past three decades, tremendous global progress in preventing and treating paediatric HIV infection has been achieved. This paper highlights the emerging health challenges of HIV-exposed uninfected (HEU) children and the ageing population of children living with HIV (CLHIV), summarises programmatic opportunities for care, and highlights currently conducted research and remaining research priorities in high HIV-prevalence settings such as South Africa. Emerging health challenges amongst HEU children and CLHIV include preterm delivery, suboptimal growth, neurodevelopmental delay, mental health challenges, infectious disease morbidity and mortality, and acute and chronic respiratory illnesses including tuberculosis, pneumonia, bronchiectasis and lymphocytic interstitial pneumonitis. CLHIV and HEU children require three different categories of care: (i) optimal routine child health services applicable to all children; (ii) routine care currently provided to all HEU children and CLHIV, such as HIV testing or viral load monitoring, respectively, and (iii) additional care for CLHIV and HEU children who may have growth, neurodevelopmental, behavioural, cognitive or other deficits such as chronic lung disease, and require varying degrees of specialised care. However, the translation thereof into practice has been hampered by various systemic challenges, including shortages of trained healthcare staff, suboptimal use of the patient-held child’s Road to Health book for screening and referral purposes, inadequate numbers and distribution of therapeutic staff, and shortages of assistive/diagnostic devices, where required. Additionally, in low-middle-income high HIV-prevalence settings, there is a lack of evidence-based solutions/models of care to optimise health amongst HEU and CLHIV. Current research priorities include understanding the mechanisms of preterm birth in women living with HIV to optimise preventive interventions; establishing pregnancy pharmacovigilance systems to understand the short-, medium- and long-term impact of in utero ART and HIV exposure; understanding the role of preconception maternal ART on HEU child infectious morbidity and long-term growth and neurodevelopmental trajectories in HEU children and CLHIV, understanding mental health outcomes and support required in HEU children and CLHIV through childhood and adolescence; monitoring HEU child morbidity and mortality compared with HIV-unexposed children; monitoring outcomes of CLHIV who initiated ART very early in life, sometimes with suboptimal ART regimens owing to medication formulation and registration issues; and testing sustainable models of care for HEU children and CLHIV including later reproductive care and support

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