Stabilization of the Electroweak Vacuum by a Scalar Threshold Effect

We show how a heavy scalar singlet with a large vacuum expectation value can evade the potential instability of the Standard Model electroweak vacuum. The quartic interaction between the heavy scalar singlet and the Higgs doublet leads to a positive tree-level threshold correction for the Higgs quartic coupling, which is very effective in stabilizing the potential. We provide examples, such as the see-saw, invisible axion and unitarized Higgs inflation, where the proposed mechanism is automatically implemented in well-defined ranges of Higgs masses.Comment: 18 pages, 5 figure

Clinical Evaluation of Exercise-Induced Physiological Changes in Military Working Dogs (MWDs) Resulting from the Use or Non-Use of Cooling Vests during Training in Moderately Hot Environments

Nose work with military working dogs (MWDs) in warmer-than-usual areas has led us to look for new tools to reduce both heat stress and the risk of heat stroke. One of the different strategies to manage heat stress is the use of cooling vests, such as those used in humans. The aim was to assess three cooling conditions (using two different cooling vests during exercise and the non-use of such garments) by measuring core body temperature, systemic blood pressure and pulse rate before and after the exercise (moment: four measurement times) in military dogs of the I Military Police Battalion (in Valencia, Spain). All dogs were evaluated under all three conditions during the three days of the study. Significant differences were observed between condition, moment, and the interaction of these two factors, in relation to core body temperature and pulse rate. Therefore, the use of an evaporative cooling vest may further be useful as a routine thermal control and conditioning measure in MWDs

Effect of luteinizing hormone on follicle stimulating hormone-activated paracrine signalling in rat ovary

‘Pure' follicle stimulating hormone (FSH) and luteinizing hormone (LH) are expected shortly to become available for pharmaceutical use in the clinical setting. To test the contribution of LH to optimal ovarian responsiveness to FSH, 21-day-old hypophysectomized, immature, female rats received four s.c. injections of recombinant human LH (rhLH; total dose 1-10 IU) and/or rhFSH (total dose 30-72 IU) given at 12-hourly intervals. At 48 h after the first injection, ovaries were removed, weighed and used to isolate granulosa and thecal/interstitial cells for assessment of basal and gonadotrophin-responsive steroidogenesis in vitro, or homogenized to extract total RNA for Northern analysis of 17-hydroxylase/C17-20-lyase (cytochrome P-450c17α) mRNA. Serum oestradiol and uterine weight were measured as indices of ovarian oestrogen production; and-rostenedione was measured to reflect ovarian androgen production. Consistent with the two-cell, two-gonadotrophin model of oestrogen synthesis, increased ovarian oestrogen secretion only occurred if both rhFSH and rhLH were given simultaneously. Treatment with rhFSH alone stimulated ovarian weight gain and granulosa cell aromatase activity without oestrogen secretion, whereas rhLH alone stimulated thecal androgen synthesis and androgen secretion. When the total rhLH dose was fixed at 1 IU, giving rise to an unmeasurably low serum concentration of rhLH, additional treatment with rhFSH (30-72 IU) dose-dependently stimulated serum androgen concentrations as well as oestrogen concentrations. The ∼2.0 kb-sized P-450c17α mRNA transcript was undetectable in the ovaries of untreated control animals but was abundant in the ovaries of positive controls treated with 15 IU of pregnant mare serum gonadotrophin. Treatment with 1 IU of rhLH alone barely induced a P-450c17α mRNA signal and treatment with 30 IU of rhFSH alone was completely ineffective. However, combined treatment with 1 IU of rhLH and 30 IU of rhFSH markedly enhanced the P-450c17α mRNA signal to a level approaching the positive-control. Since P-450c17α mRNA is expressed exclusively in thecal cells, which do not possess FSH receptors, we conclude that (i) rhFSH upregulates thecal P-450c17α mRNA and hence follicular androgen synthesis via granulosa-on-theca paracrine signalling, and (ii) tonic stimulation by rhLH is required to facilitate thecal responsiveness to this rhFSH-activated paracrine signal(s

Uncertainty Propagation and Sensitivity Analysis of Coupled Thermalhydraulic-Neutronic Nuclear Power Plant Simulations: Influence of Uncertainty in Neutronic Data

AbstractThis paper presents a study of the influence of the uncertainty in the macroscopic neutronic information for a three-dimensional PWR core model on the core power and reactivity during a Reactivity Induced Accident (RIA). The analysis uses a coupled thermal-hydraulic and neutronic model for RELAP5-PARCS. The SIMTAB methodology provides neutronic information. The statistical methodology assumes uncertainty in the macroscopic cross sections, whose pdfs are sampled and the Noether-Wilks formulas for Tolerance Intervals determine the sample size. Non-parametric statistical methods determine the intervals of tolerance and sensitivities of the sample for core power, fuel enthalpy, fuel temperatures and reactivity values