28 research outputs found

    Solitonic supersymmetry restoration

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    Q-balls are a possible feature of any model with a conserved, global U(1) symmetry and no massless, charged scalars. It is shown that for a broad class of models of metastable supersymmetry breaking they are extremely influential on the vacuum lifetime and make seemingly viable vacua catastrophically short lived. A net charge asymmetry is not required as there is often a significant range of parameter space where statistical fluctuations alone are sufficient. This effect is examined for two supersymmetry breaking scenarios. It is found that models of minimal gauge mediation (which necessarily have a messenger number U(1)) undergo a rapid, supersymmetry restoring phase transition unless the messenger mass is greater than 10^8 GeV. Similarly the ISS model, in the context of direct mediation, quickly decays unless the perturbative superpotential coupling is greater than the Standard Model gauge couplings.Comment: 17 pages, 3 figures, minor comments added, accepted for publication in JHE

    Deficit of circulating stem – progenitor cells in opiate addiction: a pilot study

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    A substantial literature describes the capacity of all addictive drugs to slow cell growth and potentiate apoptosis. Flow cytometry was used as a means to compare two lineages of circulating progenitor cells in addicted patients. Buprenorphine treated opiate addicts were compared with medical patients. Peripheral venous blood CD34+ CD45+ double positive cells were counted as haemopoietic stem cells (HSC's), and CD34+ KDR+ (VEGFR2+) cells were taken as endothelial progenitor cells (EPC's). 10 opiate dependent patients with substance use disorder (SUD) and 11 non-addicted (N-SUD) were studied. The ages were (mean + S.D.) 36.2 + 8.6 and 56.4 + 18.6 respectively (P <0.01). HSC's were not different in the SUD (2.38 + 1.09 Vs. 3.40 + 4.56 cells/mcl). EPC's were however significantly lower in the SUD (0.09 + 0.14 Vs. 0.26 + 0.20 cells/mcl; No. > 0.15, OR = 0.09, 95% C.I. 0.01–0.97), a finding of some interest given the substantially older age of the N-SUD group. These laboratory data are thus consistent with clinical data suggesting accelerated ageing in addicted humans and implicate the important stem cell pool in both addiction toxicology and ageing. They carry important policy implications for understanding the fundamental toxicology of addiction, and suggest that the toxicity both of addiction itself and of indefinite agonist maintenance therapies may have been seriously underestimated

    Cardiovascular magnetic resonance in systemic hypertension

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    Systemic hypertension is a highly prevalent potentially modifiable cardiovascular risk factor. Imaging plays an important role in the diagnosis of underlying causes for hypertension, in assessing cardiovascular complications of hypertension, and in understanding the pathophysiology of the disease process. Cardiovascular magnetic resonance (CMR) provides accurate and reproducible measures of ventricular volumes, mass, function and haemodynamics as well as uniquely allowing tissue characterization of diffuse and focal fibrosis. In addition, CMR is well suited for exclusion of common secondary causes for hypertension. We review the current and emerging clinical and research applications of CMR in hypertension

    Genetic algorithm and simulated annealing to estimate optimal process parameters of the abrasive waterjet machining

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    In this study, two computational approaches, Genetic Algorithm and Simulated Annealing, are applied to search for a set of optimal process parameters value that leads to the minimum value of machining performance. The objectives of the applied techniques are: (1) to estimate the minimum value of the machining performance compared to the machining performance value of the experimental data and regression modeling, (2) to estimate the optimal process parameters values that has to be within the range of the minimum and maximum coded values for process parameters of experimental design that are used for experimental trial and (3) to evaluate the number of iteration generated by the computational approaches that lead to the minimum value of machining performance. Set of the machining process parameters and machining performance considered in this work deal with the real experimental data of the non-conventional machining operation, abrasive waterjet. The results of this study showed that both of the computational approaches managed to estimate the optimal process parameters, leading to the minimum value of machining performance when compared to the result of real experimental data

    Effect of bivalirudin on aortic valve intervention outcomes study: a two-centre registry study comparing bivalirudin and unfractionated heparin in balloon aortic valvuloplasty

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    We sought to assess if bivalirudin use during balloon aortic valvuloplasty (BAV) would affect clinical outcomes compared with heparin. We compared the outcomes of consecutive patients who underwent elective or urgent BAV with intraprocedural use of bivalirudin or heparin at two high-volume centres. All in-hospital events post BAV were adjudicated by an independent, blinded clinical events committee. Of 427 patients, 223 patients (52.2%) received bivalirudin and 204 (47.8%) received heparin. Compared with patients who received heparin, patients who received bivalirudin had significantly less major bleeding (4.9% vs. 13.2%, p=0.003). Net adverse clinical events (NACE, major bleeding or major adverse cardiovascular events [MACE]) were also reduced (11.2% vs. 20.1%, p=0.01). There was no significant difference in the rates of MACE (mortality, myocardial infarction or stroke, 6.7% vs. 11.3%, p=0.1), or vascular complications (major, 2.7% vs. 2.0%; minor, 4.5% vs. 4.9%; p=0.83). After multivariate analysis controlling for vascular preclosure, the use of bivalirudin remained independently associated with reduced major bleeding (OR 0.37; 95% CI: 0.16 to 0.84; p=0.02) while the association was attenuated in propensity-adjusted analysis (OR 0.44, 95% CI: 0.18 to 1.07, p=0.08). In this registry of patients with severe aortic stenosis, bivalirudin as compared to heparin resulted in improved in-hospital outcomes post BAV in terms of reduced major bleeding, similar MACE and reduced NACE. If verified in a randomised study and extended to the transcatheter aortic valve implantation (TAVI) population, these results might indicate a potential benefit for patients undergoing such procedures
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