503 research outputs found

    Galois Module Structure of \Z/\ell^n-th Classes of Fields

    Full text link
    In this paper we use the Merkurjev-Suslin theorem to explore the structure of arithmetically significant Galois modules that arise from Kummer theory. Let K be a field of characteristic different from a prime \ell, n a positive integer, and suppose that K contains the (\ell^n)^th roots of unity. Let L be the maximal \Z/\ell^n-elementary abelian extension of K, and set G = \Gal(L|K). We consider the G-module J = L^\times/\ell^n and denote its socle series by J_m. We provide a precise condition, in terms of a map to H^3(G,\Z/\ell^n), determining which submodules of J_{m-1} embed in cyclic modules generated by elements of J_m. This generalizes a theorem of Adem, Gao, Karaguezian, and Minac which deals with the case m=\ell^n=2. This description of J_m/J_{m-1} can be viewed as an analogue of the classical Hilbert's Theorem 90 and it is helpful for understanding the G-module J.Comment: Final version: to appear in Bull. of the London Math So

    Matter-Antimatter Asymmetry - Aspects at Low Energy

    Get PDF
    The apparent dominance of matter over antimatter in our universe is an obvious and puzzling fact which cannot be adequately explained in present physical frameworks that assume matter-antimatter symmetry at the big bang. However, our present knowledge of starting conditions and of known sources of CP violation are both insufficient to explain the observed asymmetry. Therefore ongoing research on matter-antimatter differences is strongly motivated as well as attempts to identify viable new mechanisms that could create the present asymmetry. Here we concentrate on possible precision experiments at low energies towards a resolution of this puzzle.Comment: 6 pages, 1 figure; accepted for publication in Annalen der Physik (2015

    The Origins of Lactase Persistence in Europe

    Get PDF
    Lactase persistence (LP) is common among people of European ancestry, but with the exception of some African, Middle Eastern and southern Asian groups, is rare or absent elsewhere in the world. Lactase gene haplotype conservation around a polymorphism strongly associated with LP in Europeans (−13,910 C/T) indicates that the derived allele is recent in origin and has been subject to strong positive selection. Furthermore, ancient DNA work has shown that the −13,910*T (derived) allele was very rare or absent in early Neolithic central Europeans. It is unlikely that LP would provide a selective advantage without a supply of fresh milk, and this has lead to a gene-culture coevolutionary model where lactase persistence is only favoured in cultures practicing dairying, and dairying is more favoured in lactase persistent populations. We have developed a flexible demic computer simulation model to explore the spread of lactase persistence, dairying, other subsistence practices and unlinked genetic markers in Europe and western Asia's geographic space. Using data on −13,910*T allele frequency and farming arrival dates across Europe, and approximate Bayesian computation to estimate parameters of interest, we infer that the −13,910*T allele first underwent selection among dairying farmers around 7,500 years ago in a region between the central Balkans and central Europe, possibly in association with the dissemination of the Neolithic Linearbandkeramik culture over Central Europe. Furthermore, our results suggest that natural selection favouring a lactase persistence allele was not higher in northern latitudes through an increased requirement for dietary vitamin D. Our results provide a coherent and spatially explicit picture of the coevolution of lactase persistence and dairying in Europe

    Relationship between Exercise Capacity and Brain Size in Mammals

    Get PDF
    A great deal of experimental research supports strong associations between exercise, cognition, neurogenesis and neuroprotection in mammals. Much of this work has focused on neurogenesis in individual subjects in a limited number of species. However, no study to date has examined the relationship between exercise and neurobiology across a wide range of mammalian taxa. It is possible that exercise and neurobiology are related across evolutionary time. To test this hypothesis, this study examines the association between exercise and brain size across a wide range of mammals.Controlling for associations with body size, we examined the correlation between brain size and a proxy for exercise frequency and capacity, maximum metabolic rate (MMR; ml O(2) min(-1)). We collected brain sizes and MMRs from the literature and calculated residuals from the least-squares regression line describing the relationship between body mass and each variable of interest. We then analyzed the correlation between residual brain size and residual MMR both before and after controlling for phylogeny using phylogenetic independent contrasts. We found a significant positive correlation between maximum metabolic rate and brain size across a wide range of taxa.These results suggest a novel hypothesis that links brain size to the evolution of locomotor behaviors in a wide variety of mammalian species. In the end, we suggest that some portion of brain size in nonhuman mammals may have evolved in conjunction with increases in exercise capacity rather than solely in response to selection related to cognitive abilities

    Effects of a high-dose 24-h infusion of tranexamic acid on death and thromboembolic events in patients with acute gastrointestinal bleeding (HALT-IT): an international randomised, double-blind, placebo-controlled trial

    Get PDF
    Background: Tranexamic acid reduces surgical bleeding and reduces death due to bleeding in patients with trauma. Meta-analyses of small trials show that tranexamic acid might decrease deaths from gastrointestinal bleeding. We aimed to assess the effects of tranexamic acid in patients with gastrointestinal bleeding. Methods: We did an international, multicentre, randomised, placebo-controlled trial in 164 hospitals in 15 countries. Patients were enrolled if the responsible clinician was uncertain whether to use tranexamic acid, were aged above the minimum age considered an adult in their country (either aged 16 years and older or aged 18 years and older), and had significant (defined as at risk of bleeding to death) upper or lower gastrointestinal bleeding. Patients were randomly assigned by selection of a numbered treatment pack from a box containing eight packs that were identical apart from the pack number. Patients received either a loading dose of 1 g tranexamic acid, which was added to 100 mL infusion bag of 0·9% sodium chloride and infused by slow intravenous injection over 10 min, followed by a maintenance dose of 3 g tranexamic acid added to 1 L of any isotonic intravenous solution and infused at 125 mg/h for 24 h, or placebo (sodium chloride 0·9%). Patients, caregivers, and those assessing outcomes were masked to allocation. The primary outcome was death due to bleeding within 5 days of randomisation; analysis excluded patients who received neither dose of the allocated treatment and those for whom outcome data on death were unavailable. This trial was registered with Current Controlled Trials, ISRCTN11225767, and ClinicalTrials.gov, NCT01658124. Findings: Between July 4, 2013, and June 21, 2019, we randomly allocated 12 009 patients to receive tranexamic acid (5994, 49·9%) or matching placebo (6015, 50·1%), of whom 11 952 (99·5%) received the first dose of the allocated treatment. Death due to bleeding within 5 days of randomisation occurred in 222 (4%) of 5956 patients in the tranexamic acid group and in 226 (4%) of 5981 patients in the placebo group (risk ratio [RR] 0·99, 95% CI 0·82–1·18). Arterial thromboembolic events (myocardial infarction or stroke) were similar in the tranexamic acid group and placebo group (42 [0·7%] of 5952 vs 46 [0·8%] of 5977; 0·92; 0·60 to 1·39). Venous thromboembolic events (deep vein thrombosis or pulmonary embolism) were higher in tranexamic acid group than in the placebo group (48 [0·8%] of 5952 vs 26 [0·4%] of 5977; RR 1·85; 95% CI 1·15 to 2·98). Interpretation: We found that tranexamic acid did not reduce death from gastrointestinal bleeding. On the basis of our results, tranexamic acid should not be used for the treatment of gastrointestinal bleeding outside the context of a randomised trial

    Effect of clinical signs, endocrinopathies, timing of surgery, hyperlipidemia, and hyperbilirubinemia on outcome in dogs with gallbladder mucocele

    Get PDF
    Gallbladder mucocele (GBM) is a common extra-hepatic biliary syndrome in dogs with death rates ranging from 7 to 45%. Therefore, the aim of this study was to identify the association of survival with variables that could be utilized to improve clinical decisions. A total of 1194 dogs with a gross and histopathological diagnosis of GBM were included from 41 veterinary referral hospitals in this retrospective study. Dogs with GBM that demonstrated abnormal clinical signs had significantly greater odds of death than subclinical dogs in a univariable analysis (OR, 4.2; 95% CI, 2.14–8.23; P < 0.001). The multivariable model indicated that categorical variables including owner recognition of jaundice (OR, 2.12; 95% CI, 1.19–3.77; P = 0.011), concurrent hyperadrenocorticism (OR 1.94; 95% CI, 1.08–3.47; P = 0.026), and Pomeranian breed (OR, 2.46; 95% CI 1.10–5.50; P = 0.029) were associated with increased odds of death, and vomiting was associated with decreased odds of death (OR, 0.48; 95% CI, 0.30–0.72; P = 0.001). Continuous variables in the multivariable model, total serum/plasma bilirubin concentration (OR, 1.03; 95% CI, 1.01–1.04; P < 0.001) and age (OR, 1.17; 95% CI, 1.08–1.26; P < 0.001), were associated with increased odds of death. The clinical utility of total serum/plasma bilirubin concentration as a biomarker to predict death was poor with a sensitivity of 0.61 (95% CI, 0.54–0.69) and a specificity of 0.63 (95% CI, 0.59–0.66). This study identified several prognostic variables in dogs with GBM including total serum/plasma bilirubin concentration, age, clinical signs, concurrent hyperadrenocorticism, and the Pomeranian breed. The presence of hypothyroidism or diabetes mellitus did not impact outcome in this study.Supplemental Table S1. Number of dogs included from each institution and years reviewed.Supplemental Table S2. Included breeds.Supplemental Table S3. Distribution of various reasons given for performing cholecystectomy in the 179 subclinical dogs with gallbladder mucocele (GBM).Supplemental Table S4. Distribution of clinical signs associated with systemic illness in 982 dogs with gallbladder mucocele.Supplemental Table S5. Distribution of reasons for death in-hospital (i.e. euthanized and died) in 179 dogs with gallbladder mucocele that underwent cholecystectomy.http://www.elsevier.com/locate/tvjlhj2020Companion Animal Clinical Studie

    Is Robenacoxib Superior to Meloxicam in Improving Patient Comfort in Dogs Diagnosed With a Degenerative Joint Process?

    No full text
    Clinical bottom lineAt normal clinical doses, there is no evidence that robenacoxib would provide superior patient comfort compared to meloxicam.</p

    Investigating the Use of Gastroprotectants as a Means of Preventing Iatrogenic Gastrointestinal Signs Associated With Immunosuppressive Corticosteroid Therapy. A Retrospective Study

    No full text
    Background: Gastroprotectants are commonly prescribed in patients receiving immunosuppressive therapy with glucocorticoids. Presently, there is limited evidence to support such use of gastroprotectants.Objectives: To establish if the prophylactic use of gastroprotectants was associated with a reduced incidencer of gastrointestinal signs in dogs receiving immunosuppressive doses of glucocorticoids, compared to not receiving prophylactic gastroprotectants.Methods: Retrospective observational study. The case log of a University referral hospital was examined between September 2009 and September 2015 for dogs diagnosed with primary, immune-mediated disease. Those receiving ≥1mg/kg/day prednisolone or equivalent as part of their treatment were included. Dogs displaying gastrointestinal signs (vomiting, diarrhoea, regurgitation or haematochezia) in the preceding 7 days or those diagnosed with immune-mediated thrombocytopenia were excluded. Statistical significance was P&lt;0.05.Results: One hundred and twenty-seven dogs were enrolled. All dogs received prednisolone; median (range) dose 2 (1- 4.4) mg/kg/day. Seventy-six dogs received a gastroprotectant. Sixty-three dogs received them concurrent to glucocorticoids (“prophylactic” group) and thirteen dogs received gastroprotectants after starting glucocorticoids, without experiencing gastrointestinal signs (“post-exposure” group). Fifty-one dogs received no gastroprotectants (“no gastroprotectant” group). Overall 34/127 (26.8%) dogs developed gastrointestinal signs; 8/51 (15.7%) in the “no gastroprotectant” group and 26/76 (34.2%) of dogs receiving gastroprotectants. This difference was significant (P= 0.016) between groups. There was no significant difference between the “prophylactic group” (18/63; 28.6%) and “post-exposure” group (8/13; 61.5%), or between the “prophylactic” and “no gastroprotectant” groups in the incidence of gastrointestinal signs.Conclusions: Gastroprotectants are associated with a higher incidence of gastrointestinal signs and conferred no identifiable benefits. Prospective randomised trials are required to validate these findings. <img src="https://www.veterinaryevidence.org/rcvskmod/icons/oa-icon.jpg" alt="Open Access" /
    corecore