187 research outputs found
B-L Cosmic Strings in Heterotic Standard Models
E_{8} X E_{8} heterotic string and M-theory, when compactified on smooth
Calabi-Yau manifolds with SU(4) vector bundles, can give rise to softly broken
N=1 supersymmetric theories with the exact matter spectrum of the MSSM,
including three right-handed neutrinos and one Higgs-Higgs conjugate pair of
supermultiplets. These vacua have the SU(3)_{C} X SU(2)_{L} X U(1)_{Y} gauge
group of the standard model augmented by an additional gauged U(1)_{B-L}. Their
minimal content requires that the B-L symmetry be spontaneously broken by a
vacuum expectation value of at least one right-handed sneutrino. The soft
supersymmetry breaking operators can induce radiative breaking of the B-L gauge
symmetry with an acceptable B-L/electroweak hierarchy. In this paper, it is
shown that U(1)_{B-L} cosmic strings occur in this context, potentially with
both bosonic and fermionic superconductivity. We present a numerical analysis
that demonstrates that boson condensates can, in principle, form for theories
of this type. However, the weak Yukawa and gauge couplings of the right-handed
sneutrino suggests that bosonic superconductivity will not occur in the
simplest vacua in this context. The electroweak phase transition also disallows
fermion superconductivity, although substantial bound state fermion currents
can exist.Comment: 41 pages, 5 figure
CP violation Beyond the MSSM: Baryogenesis and Electric Dipole Moments
We study electroweak baryogenesis and electric dipole moments in the presence
of the two leading-order, non-renormalizable operators in the Higgs sector of
the MSSM. Significant qualitative and quantitative differences from MSSM
baryogenesis arise due to the presence of new CP-violating phases and to the
relaxation of constraints on the supersymmetric spectrum (in particular, both
stops can be light). We find: (1) spontaneous baryogenesis, driven by a change
in the phase of the Higgs vevs across the bubble wall, becomes possible; (2)
the top and stop CP-violating sources can become effective; (3) baryogenesis is
viable in larger parts of parameter space, alleviating the well-known
fine-tuning associated with MSSM baryogenesis. Nevertheless, electric dipole
moments should be measured if experimental sensitivities are improved by about
one order of magnitude.Comment: 33 pages, 6 figure
The relationship between low back pain and leisure time physical activity in a working population of cleaners - a study with weekly follow-ups for 1 year
<p>Abstract</p> <p>Background</p> <p>Low back pain (LBP) and leisure time physical activity (LTPA) are considered to be closely related, and clinical guidelines for the treatment of acute LBP recommend patients stay physically active. However, the documentation for this recommendation is sparse and based on studies involving patient populations. The purpose of the study was (1) to investigate the correlation between LBP and LTPA on a weekly basis over the course of a year in a high-risk group of cleaners; and (2) to investigate if maintaining LTPA during an episode of acute LBP has a positive effect on LBP intensity in the subsequent 4 weeks.</p> <p>Methods</p> <p>188 cleaners consented to participate in a 52-week text message survey about hours of LTPA and intensity of LBP (from 0 to 9) over the previous 7 days. The correlation between LBP and LTPA was calculated by Pearson correlation coefficient. During an episode of acute LBP, a mixed effect logistic regression model was used to investigate whether cleaners who maintain LTPA have a lower pain intensity and higher probability of returning to initial pain intensity within the following four weeks compared with cleaners who decrease LTPA during acute LBP.</p> <p>Results</p> <p>The correlation between weekly LTPA and LBP data was negative, but numerically low (r = -0.069) and statistically insignificant (<it>p </it>= 0.08). Among the 82 cleaners experiencing at least one episode of acute LBP, those maintaining LTPA during an episode of acute LBP did not have a lower pain intensity (average LBP intensity difference between groups of 0.06; 95% confidence interval (95% CI) of -0.417 to 0.539) or higher probability of returning to initial pain level (Odds ratio 1,02; 95% CI of 0.50 to 2.09) in the following four weeks compared with cleaners decreasing LTPA during acute LBP.</p> <p>Conclusions</p> <p>Hours of LTPA and intensity of LBP measured on a weekly basis throughout a year showed no close correlation. Maintaining LTPA during an episode of acute LBP did not result in a positive effect on LBP in the following 4 weeks. Documentation of LTPA recommendations for acute LBP in working populations is still needed.</p
Composite GUTs: models and expectations at the LHC
We investigate grand unified theories (GUTs) in scenarios where electroweak
(EW) symmetry breaking is triggered by a light composite Higgs, arising as a
Nambu-Goldstone boson from a strongly interacting sector. The evolution of the
standard model (SM) gauge couplings can be predicted at leading order, if the
global symmetry of the composite sector is a simple group G that contains the
SM gauge group. It was noticed that, if the right-handed top quark is also
composite, precision gauge unification can be achieved. We build minimal
consistent models for a composite sector with these properties, thus
demonstrating how composite GUTs may represent an alternative to supersymmetric
GUTs. Taking into account the new contributions to the EW precision parameters,
we compute the Higgs effective potential and prove that it realizes
consistently EW symmetry breaking with little fine-tuning. The G group
structure and the requirement of proton stability determine the nature of the
light composite states accompanying the Higgs and the top quark: a coloured
triplet scalar and several vector-like fermions with exotic quantum numbers. We
analyse the signatures of these composite partners at hadron colliders:
distinctive final states contain multiple top and bottom quarks, either alone
or accompanied by a heavy stable charged particle, or by missing transverse
energy.Comment: 55 pages, 13 figures, final version to be published in JHE
The Occurrence of Photorhabdus-Like Toxin Complexes in Bacillus thuringiensis
Recently, genomic sequencing of a Bacillus thuringiensis (Bt) isolate from our collection revealed the presence of an apparent operon encoding an insecticidal toxin complex (Tca) similar to that first described from the entomopathogen Photorhabdus luminescens. To determine whether these genes are widespread among Bt strains, we screened isolates from the collection for the presence of tccC, one of the genes needed for the expression of fully functional toxin complexes. Among 81 isolates chosen to represent commonly encountered biochemical phenotypes, 17 were found to possess a tccC. Phylogenetic analysis of the 81 isolates by multilocus sequence typing revealed that all the isolates possessing a tccC gene were restricted to two sequence types related to Bt varieties morrisoni, tenebrionis, israelensis and toumanoffi. Sequencing of the ∼17 kb tca operon from two isolates representing each of the two sequence types revealed >99% sequence identity. Optical mapping of DNA from Bt isolates representing each of the sequence types revealed nearly identical plasmids of ca. 333 and 338 kbp, respectively. Selected isolates were found to be toxic to gypsy moth larvae, but were not as effective as a commercial strain of Bt kurstaki. Some isolates were found to inhibit growth of Colorado potato beetle. Custom Taqman® relative quantitative real-time PCR assays for Tc-encoding Bt revealed both tcaA and tcaB genes were expressed within infected gypsy moth larvae
Evaluation of the impact of universal testing for gestational diabetes mellitus on maternal and neonatal health outcomes: a retrospective analysis
Background: Gestational diabetes (GDM) affects a substantial proportion of women in pregnancy and is associated with increased risk of adverse perinatal and long term outcomes. Treatment seems to improve perinatal outcomes, the relative effectiveness of different strategies for identifying women with GDM however is less clear. This paper describes an evaluation of the impact of a change in policy from selective risk factor based offering, to universal offering of an oral glucose tolerance test (OGTT) to identify women with GDM on maternal and neonatal outcomes. Methods: Retrospective six year analysis of 35,674 births at the Women’s and Newborn unit, Bradford Royal Infirmary, United Kingdom. Results: The proportion of the whole obstetric population diagnosed with GDM increased almost fourfold following universal offering of an OGTT compared to selective offering of an OGTT; Rate Ratio (RR) 3.75 (95% CI 3.28 to 4.29), the proportion identified with severe hyperglycaemia doubled following the policy change; 1.96 (1.50 to 2.58). The case detection rate however, for GDM in the whole population and severe hyperglycaemia in those with GDM reduced by 50-60%; 0.40 (0.35 to 0.46) and 0.51 (0.39 to 0.67) respectively. Universally offering an OGTT was associated with an increased induction of labour rate in the whole obstetric population and in women with GDM; 1.43 (1.35 to 1.50) and 1.21 (1.00 to1.49) respectively. Caesarean section, macrosomia and perinatal mortality rates in the whole population were similar. For women with GDM, rate of caesarean section; 0.70 (0.57 to 0.87), macrosomia; 0.22 (0.15 to 0.34) and perinatal mortality 0.12 (0.03 to 0.46) decreased following the policy change. Conclusions: Universally offering an OGTT was associated with increased identification of women with GDM and severe hyperglycaemia and with neonatal benefits for those with GDM. There was no evidence of benefit or adverse effects in neonatal outcomes in the whole obstetric population
Risk factor screening to identify women requiring oral glucose tolerance testing to diagnose gestational diabetes : a systematic review and meta-analysis and analysis of two pregnancy cohorts
BACKGROUND: Easily identifiable risk factors including: obesity and ethnicity at high risk of diabetes are commonly used to indicate which women should be offered the oral glucose tolerance test (OGTT) to diagnose gestational diabetes (GDM). Evidence regarding these risk factors is limited however. We conducted a systematic review (SR) and meta-analysis and individual participant data (IPD) analysis to evaluate the performance of risk factors in identifying women with GDM. METHODS: We searched MEDLINE, Medline in Process, Embase, Maternity and Infant Care and the Cochrane Central Register of Controlled Trials (CENTRAL) up to August 2016 and conducted additional reference checking. We included observational, cohort, case-control and cross-sectional studies reporting the performance characteristics of risk factors used to identify women at high risk of GDM. We had access to IPD from the Born in Bradford and Atlantic Diabetes in Pregnancy cohorts, all pregnant women in the two cohorts with data on risk factors and OGTT results were included. RESULTS: Twenty nine published studies with 211,698 women for the SR and a further 14,103 women from two birth cohorts (Born in Bradford and the Atlantic Diabetes in Pregnancy study) for the IPD analysis were included. Six studies assessed the screening performance of guidelines; six examined combinations of risk factors; eight evaluated the number of risk factors and nine examined prediction models or scores. Meta-analysis using data from published studies suggests that irrespective of the method used, risk factors do not identify women with GDM well. Using IPD and combining risk factors to produce the highest sensitivities, results in low specificities (and so higher false positives). Strategies that use the risk factors of age (>25 or >30) and BMI (>25 or 30) perform as well as other strategies with additional risk factors included. CONCLUSIONS: Risk factor screening methods are poor predictors of which pregnant women will be diagnosed with GDM. A simple approach of offering an OGTT to women 25 years or older and/or with a BMI of 25kg/m2 or more is as good as more complex risk prediction models. Research to identify more accurate (bio)markers is needed. Systematic Review Registration: PROSPERO CRD42013004608
Clinical characteristics and patterns of healthcare utilization in patients with painful neuropathic disorders in UK general practice: a retrospective cohort study
<p>Abstract</p> <p>Background</p> <p>Clinical characteristics and patterns of healthcare utilization in patients with painful neuropathic disorders (PNDs) who are under the care of general practitioners (GPs) in the UK are not well understood.</p> <p>Methods</p> <p>Using a large electronic UK database, we identified all adults (age ≥ 18 years) with any GP encounters between 1 January 2006 - 31 December 2006 at which a diagnosis of PND was noted ("PND patients"). An age-and gender-matched comparison group also was constituted consisting of randomly selected patients with one or more GP encounters-but no mention of PNDs-during this period. Characteristics and patterns of healthcare utilization of patients in the two groups were then examined over the one-year study period.</p> <p>Results</p> <p>The study sample consisted of 31,688 patients with mention of PNDs and an equal number of matched comparators; mean age was 56 years, and 62% were women. The prevalence of various comorbidities was higher among patients in the PND group, including digestive disorders (31% vs. 17% for comparison group), circulatory disorders (29% vs. 22%), and depression (4% vs. 3%) (all <it>p </it>< 0.01). Receipt of prescriptions for pain-related pharmacotherapy also was higher among PND patients, including nonsteroidal anti-inflammatory drugs (56% of PND patients had one or more such prescriptions vs. only 22% in the comparison group), opioids (49% vs. 12%), tricyclic antidepressants (20% vs. 1%), and antiepileptics (12% vs. 1%) (all <it>p </it>< 0.01). PND patients also averaged significantly more GP visits (22.8 vs. 14.2) and referrals to specialists (2.8 vs. 1.4) over one year (both comparisons <it>p </it>< 0.01).</p> <p>Conclusions</p> <p>Patients with PNDs under the care of GPs in the UK have relatively high levels of use of healthcare services and pain-related pharmacotherapy.</p
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