952 research outputs found
General Messenger Gauge Mediation
We discuss theories of gauge mediation in which the hidden sector consists of
two subsectors which are weakly coupled to each other. One sector is made up of
messengers and the other breaks supersymmetry. Each sector by itself may be
strongly coupled. We provide a unifying framework for such theories and discuss
their predictions in different settings. We show how this framework
incorporates all known models of messengers. In the case of weakly-coupled
messengers interacting with spurions through the superpotential, we prove that
the sfermion mass-squared is positive, and furthermore, that there is a lower
bound on the ratio of the sfermion mass to the gaugino mass.Comment: 37 pages; minor change
Strategies for implementing placental transfusion at birth: a systematic review
Background: Enhanced placental transfusion reduces adverse neonatal outcomes, including death. Despite being endorsed by the World Health Organization in 2012, the method has not been adopted widely in practice.
Methods: We performed a systematic literature search and included quality improvement projects on placental transfusion at birth and studies on barriers to implementation. We extracted information on population, methods of implementation, obstacles to implementation, and strategies to overcome them.
Results: We screened 99 studies out of which 18 were included in the review. The preferred methods of implementation were protocol development (86% of studies) reinforced by targeted education (64% of studies) and multidisciplinary team involvement (43% of studies). Barriers to implementation were mentioned in 12 studies and divided into four categories: general factors such as lack of staff awareness (5 studies) and professional resistance to change (5 studies); obstetricianâspecific concerns, including the impact during cesarean (3 studies) and the risk of postpartum hemorrhage (3 studies); pediatricianâspecific concerns, including the need for resuscitation (5 studies), risk of jaundice (3 studies), and polycythemia (2 studies); and logistical difficulties. The main strategies to facilitate placental transfusion at birth included effective multidisciplinary team collaboration, protocol development, targeted education, and constructive feedback sessions.
Conclusions: Placental transfusion implementation requires a multidisciplinary approach, with obstetricians, midwives, nurses, and pediatricians central to adoption of the practice. Understanding the obstacles to implementation informs strategies to increase placental transfusion adoption of practice worldwide. We suggest a stepwise approach to implementation and enhancement of placental transfusion into practice
Insulin resistance in type 1 diabetes: what is âdouble diabetesâ and what are the risks?
In this review, we explore the concept of âdouble diabetesâ, a combination of type 1 diabetes with features of insulin resistance and type 2 diabetes. After considering whether double diabetes is a useful concept, we discuss potential mechanisms of increased insulin resistance in type 1 diabetes before examining the extent to which double diabetes might increase the risk of cardiovascular disease (CVD). We then go on to consider the proposal that weight gain from intensive insulin regimens may be associated with increased CV risk factors in some patients with type 1 diabetes, and explore the complex relationships between weight gain, insulin resistance, glycaemic control and CV outcome. Important comparisons and contrasts between type 1 diabetes and type 2 diabetes are highlighted in terms of hepatic fat, fat partitioning and lipid profile, and how these may differ between type 1 diabetic patients with and without double diabetes. In so doing, we hope this work will stimulate much-needed research in this area and an improvement in clinical practice
Control and Characterization of Individual Grains and Grain Boundaries in Graphene Grown by Chemical Vapor Deposition
The strong interest in graphene has motivated the scalable production of high
quality graphene and graphene devices. Since large-scale graphene films
synthesized to date are typically polycrystalline, it is important to
characterize and control grain boundaries, generally believed to degrade
graphene quality. Here we study single-crystal graphene grains synthesized by
ambient CVD on polycrystalline Cu, and show how individual boundaries between
coalescing grains affect graphene's electronic properties. The graphene grains
show no definite epitaxial relationship with the Cu substrate, and can cross Cu
grain boundaries. The edges of these grains are found to be predominantly
parallel to zigzag directions. We show that grain boundaries give a significant
Raman "D" peak, impede electrical transport, and induce prominent weak
localization indicative of intervalley scattering in graphene. Finally, we
demonstrate an approach using pre-patterned growth seeds to control graphene
nucleation, opening a route towards scalable fabrication of single-crystal
graphene devices without grain boundaries.Comment: New version with additional data. Accepted by Nature Material
Microbial ligand costimulation drives neutrophilic steroid-refractory asthma
Funding: The authors thank the Wellcome Trust (102705) and the Universities of Aberdeen and Cape Town for funding. This research was also supported, in part, by National Institutes of Health GM53522 and GM083016 to DLW. KF and BNL are funded by the Fonds Wetenschappelijk Onderzoek, BNL is the recipient of an European Research Commission consolidator grant and participates in the European Union FP7 programs EUBIOPRED and MedALL. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD
The Cost-Effectiveness of Reclassification Sampling for Prevalence Estimation
Typically, a two-phase (double) sampling strategy is employed when classifications are subject to error and there is a gold standard (perfect) classifier available. Two-phase sampling involves classifying the entire sample with an imperfect classifier, and a subset of the sample with the gold-standard.In this paper we consider an alternative strategy termed reclassification sampling, which involves classifying individuals using the imperfect classifier more than one time. Estimates of sensitivity, specificity and prevalence are provided for reclassification sampling, when either one or two binary classifications of each individual using the imperfect classifier are available. Robustness of estimates and design decisions to model assumptions are considered. Software is provided to compute estimates and provide advice on the optimal sampling strategy.Reclassification sampling is shown to be cost-effective (lower standard error of estimates for the same cost) for estimating prevalence as compared to two-phase sampling in many practical situations
Adjuvant Sorafenib for Renal Cell Carcinoma at Intermediate or High Risk of Relapse: Results From the SORCE Randomized Phase III Intergroup Trial
PURPOSE: SORCE is an international, randomized, double-blind, three-arm trial of sorafenib after surgical excision of primary renal cell carcinoma (RCC) found to be at intermediate or high risk of recurrence. /
PATIENTS AND METHODS: We randomly assigned participants (2:3:3) to 3 years of placebo (arm A), 1 year of sorafenib followed by 2 years of placebo (arm B), or 3 years of sorafenib (arm C). The initial sorafenib dose was 400 mg twice per day orally, amended to 400 mg daily. The primary outcome analysis, which was revised as a result of external results, was investigator-reported disease-free survival (DFS) comparing 3 years of sorafenib versus placebo. /
RESULTS: Between July 2007 and April 2013, we randomly assigned 1,711 participants (430, 642, and 639 participants in arms A, B, and C, respectively). Median age was 58 years, 71% of patients were men, 84% had clear cell histology, 53% were at intermediate risk of recurrence, and 47% were at high risk of recurrence. We observed no differences in DFS or overall survival in all randomly assigned patients, patients with high risk of recurrence, or patients with clear cell RCC only. Median DFS was not reached for 3 years of sorafenib or for placebo (hazard ratio, 1.01; 95% CI, 0.83 to 1.23; P = .95). We observed nonproportional hazards; the restricted mean survival time (RMST) was 6.81 years for 3 years of sorafenib and 6.82 years for placebo (RMST difference, 0.01 year; 95% CI, â0.49 to 0.48 year; P = .99). Despite offering treatment adaptations, more than half of participants stopped treatment by 12 months. Grade 3 hand-foot skin reaction was reported in 24% of participants on sorafenib. /
CONCLUSION: Sorafenib should not be used as adjuvant therapy for RCC. Active surveillance remains the standard of care for patients at intermediate or high risk of recurrence after nephrectomy and is the appropriate control of our current international adjuvant RCC trial, RAMPART
The role of multiple marks in epigenetic silencing and the emergence of a stable bivalent chromatin state
We introduce and analyze a minimal model of epigenetic silencing in budding
yeast, built upon known biomolecular interactions in the system. Doing so, we
identify the epigenetic marks essential for the bistability of epigenetic
states. The model explicitly incorporates two key chromatin marks, namely H4K16
acetylation and H3K79 methylation, and explores whether the presence of
multiple marks lead to a qualitatively different systems behavior. We find that
having both modifications is important for the robustness of epigenetic
silencing. Besides the silenced and transcriptionally active fate of chromatin,
our model leads to a novel state with bivalent (i.e., both active and
silencing) marks under certain perturbations (knock-out mutations, inhibition
or enhancement of enzymatic activity). The bivalent state appears under several
perturbations and is shown to result in patchy silencing. We also show that the
titration effect, owing to a limited supply of silencing proteins, can result
in counter-intuitive responses. The design principles of the silencing system
is systematically investigated and disparate experimental observations are
assessed within a single theoretical framework. Specifically, we discuss the
behavior of Sir protein recruitment, spreading and stability of silenced
regions in commonly-studied mutants (e.g., sas2, dot1) illuminating the
controversial role of Dot1 in the systems biology of yeast silencing.Comment: Supplementary Material, 14 page
- âŠ