155 research outputs found
Electroweak Radiative Corrections to Associated WH and ZH Production at Hadron Colliders
Higgs-boson production in association with W or Z bosons, p pbar -> WH/ZH +
X, is the most promising discovery channel for a light Standard Model Higgs
particle at the Fermilab Tevatron. We present the calculation of the
electroweak O(alpha) corrections to these processes. The corrections decrease
the theoretical prediction by up to 5-10%, depending in detail on the
Higgs-boson mass and the input-parameter scheme. We update the cross-section
prediction for associated WH and ZH production at the Tevatron and at the LHC,
including the next-to-leading order electroweak and QCD corrections, and study
the theoretical uncertainties induced by factorization and renormalization
scale dependences and by the parton distribution functions.Comment: 32 pages, LaTeX, 21 figures. Uses axodraw.sty and feynarts.sty. Added
reference
Quantum gauge models without classical Higgs mechanism
We examine the status of massive gauge theories, such as those usually
obtained by spontaneous symmetry breakdown, from the viewpoint of causal
(Epstein-Glaser) renormalization. The BRS formulation of gauge invariance in
this framework, starting from canonical quantization of massive (as well as
massless) vector bosons as fundamental entities, and proceeding perturbatively,
allows one to rederive the reductive group symmetry of interactions, the need
for scalar fields in gauge theory, and the covariant derivative. Thus the
presence of higgs particles is explained without recourse to a
Higgs(-Englert-Brout-Guralnik-Hagen-Kibble) mechanism. Along the way, we dispel
doubts about the compatibility of causal gauge invariance with grand unified
theories.Comment: 20 pages in two-column EPJC format, shortened version accepted for
publication. For more details, consult version
A dynamic folded hairpin conformation is associated with α-globin activation in erythroid cells
We investigate the three-dimensional (3D) conformations of the α-globin locus at the single-allele level in murine embryonic stem cells (ESCs) and erythroid cells, combining polymer physics models and high-resolution Capture-C data. Model predictions are validated against independent fluorescence in situ hybridization (FISH) data measuring pairwise distances, and Tri-C data identifying three-way contacts. The architecture is rearranged during the transition from ESCs to erythroid cells, associated with the activation of the globin genes. We find that in ESCs, the spatial organization conforms to a highly intermingled 3D structure involving non-specific contacts, whereas in erythroid cells the α-globin genes and their enhancers form a self-contained domain, arranged in a folded hairpin conformation, separated from intermingling flanking regions by a thermodynamic mechanism of micro-phase separation. The flanking regions are rich in convergent CTCF sites, which only marginally participate in the erythroid-specific gene-enhancer contacts, suggesting that beyond the interaction of CTCF sites, multiple molecular mechanisms cooperate to form an interacting domain
A remarkable case of HbH disease illustrates the relative contributions of the alpha-globin enhancers to gene expression
Genetics of disease, diagnosis and treatmen
Vegetable oil sources in diets for freshwater angelfish (Pterophyllum scalare, Cichlidae): growth and thermal tolerance
The influence of fatty acid composition of the diets on the productive performance and on cold and heat tolerance of juvenile freshwater angelfish (Pterophyllum scalare), in three different phases, was studied. Phase I studied the productive performance of freshwater angelfish in a completely randomized experimental design with four treatments, canola, linseed, olive and soybean oils and four replicates during 50 days using 192 fish in 16 aquaria. Phase II studied the cold tolerance of juvenile freshwater angelfish using 72 juvenile freshwater angelfish, coming from phase I and maintained in 12 aquaria climatized chamber. The temperature was reduced 1ºC per day, until the observation of 100% fish mortality. Phase III, it was studied the heat tolerance of juvenile freshwater angelfish employing an identical procedure to phase II, but with a daily increase of 1ºC. Significant differences (P>0.05) were not observed for any parameters evaluated. Thus, it was concluded that the type of vegetable oil (canola, linseed, olive and soybean) used as a diet supplement did not affect the productive performance, nor the tolerance to cold and heat, of juvenile freshwater angelfish
The neutralizing antibody, LY-CoV555, protects against SARS-CoV-2 infection in nonhuman primates
Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) poses a public health threat for which preventive and therapeutic agents are urgently needed. Neutralizing antibodies are a key class of therapeutics that may bridge widespread vaccination campaigns and offer a treatment solution in populations less responsive to vaccination. Here, we report that high-throughput microfluidic screening of antigen-specific B cells led to the identification of LY-CoV555 (also known as bamlanivimab), a potent anti-spike neutralizing antibody from a hospitalized, convalescent patient with coronavirus disease 2019 (COVID-19). Biochemical, structural, and functional characterization of LY-CoV555 revealed high-affinity binding to the receptor-binding domain, angiotensin-converting enzyme 2 binding inhibition, and potent neutralizing activity. A pharmacokinetic study of LY-CoV555 conducted in cynomolgus monkeys demonstrated a mean half-life of 13 days and a clearance of 0.22 ml hour−1 kg−1, consistent with a typical human therapeutic antibody. In a rhesus macaque challenge model, prophylactic doses as low as 2.5 mg/kg reduced viral replication in the upper and lower respiratory tract in samples collected through study day 6 after viral inoculation. This antibody has entered clinical testing and is being evaluated across a spectrum of COVID-19 indications, including prevention and treatment
De novo variants in the RNU4-2 snRNA cause a frequent neurodevelopmental syndrome
Around 60% of individuals with neurodevelopmental disorders (NDD) remain undiagnosed after comprehensive genetic testing, primarily of protein-coding genes1. Large genome-sequenced cohorts are improving our ability to discover new diagnoses in the non-coding genome. Here, we identify the non-coding RNA RNU4-2 as a syndromic NDD gene. RNU4-2 encodes the U4 small nuclear RNA (snRNA), which is a critical component of the U4/U6.U5 tri-snRNP complex of the major spliceosome2. We identify an 18 bp region of RNU4-2 mapping to two structural elements in the U4/U6 snRNA duplex (the T-loop and Stem III) that is severely depleted of variation in the general population, but in which we identify heterozygous variants in 115 individuals with NDD. Most individuals (77.4%) have the same highly recurrent single base insertion (n.64_65insT). In 54 individuals where it could be determined, the de novo variants were all on the maternal allele. We demonstrate that RNU4-2 is highly expressed in the developing human brain, in contrast to RNU4-1 and other U4 homologs. Using RNA-sequencing, we show how 5’ splice site usage is systematically disrupted in individuals with RNU4-2 variants, consistent with the known role of this region during spliceosome activation. Finally, we estimate that variants in this 18 bp region explain 0.4% of individuals with NDD. This work underscores the importance of non-coding genes in rare disorders and will provide a diagnosis to thousands of individuals with NDD worldwide
The Cholecystectomy As A Day Case (CAAD) score: a validated score of preoperative predictors of successful day-case cholecystectomy using the CholeS data set
Background:
Day-case surgery is associated with significant patient and cost benefits. However, only 43% of cholecystectomy patients are discharged home the same day. One hypothesis is day-case cholecystectomy rates, defined as patients discharged the same day as their operation, may be improved by better assessment of patients using standard preoperative variables.
Methods:
Data were extracted from a prospectively collected data set of cholecystectomy patients from 166 UK and Irish hospitals (CholeS). Cholecystectomies performed as elective procedures were divided into main (75%) and validation (25%) data sets. Preoperative predictors were identified, and a risk score of failed day case was devised using multivariate logistic regression. Receiver operating curve analysis was used to validate the score in the validation data set.
Results:
Of the 7426 elective cholecystectomies performed, 49% of these were discharged home the same day. Same-day discharge following cholecystectomy was less likely with older patients (OR 0.18, 95% CI 0.15–0.23), higher ASA scores (OR 0.19, 95% CI 0.15–0.23), complicated cholelithiasis (OR 0.38, 95% CI 0.31 to 0.48), male gender (OR 0.66, 95% CI 0.58–0.74), previous acute gallstone-related admissions (OR 0.54, 95% CI 0.48–0.60) and preoperative endoscopic intervention (OR 0.40, 95% CI 0.34–0.47). The CAAD score was developed using these variables. When applied to the validation subgroup, a CAAD score of ≤5 was associated with 80.8% successful day-case cholecystectomy compared with 19.2% associated with a CAAD score >5 (p < 0.001).
Conclusions:
The CAAD score which utilises data readily available from clinic letters and electronic sources can predict same-day discharges following cholecystectomy
Measurements of production cross sections of polarized same-sign W boson pairs in association with two jets in proton-proton collisions at s=13 TeV
The first measurements of production cross sections of polarized same-sign W±W±boson pairs in proton-proton collisions are reported. The measurements are based on a data sample collected with the CMS detector at the LHC at a center-of-mass energy of 13TeV, corresponding to an integrated luminosity of 137fb−1. Events are selected by requiring exactly two same-sign leptons, electrons or muons, moderate missing transverse momentum, and two jets with a large rapidity separation and a large dijet mass to enhance the contribution of same-sign W±W±scattering events. An observed (expected) 95% confidence level upper limit of 1.17 (0.88)fbis set on the production cross section for longitudinally polarized same-sign W±W±boson pairs. The electroweak production of same-sign W±W±boson pairs with at least one of the Wbosons longitudinally polarized is measured with an observed (expected) significance of 2.3 (3.1) standard deviations.SCOAP
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