67 research outputs found

    Simple thermodynamic model for the hydrogen phase diagram

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    We describe a classical thermodynamic model that reproduces the main features of the solid hydrogen phase diagram. In particular, we show how the general structure types that are found by electronic structure calculations and the quantum nature of the protons can also be understood from a classical viewpoint. The model provides a picture not only of crystal structure, but also for the anomalous melting curve and insights into isotope effects, liquid metallisation and InfraRed activity. The existence of a classical picture for this most quantum of condensed matter systems provides a surprising extension of the correspondence principle of quantum mechanics, in particular the equivalent effects of classical and quantum uncertainty.Comment: Final author versio

    Heritability of subcortical volumetric traits in mesial temporal lobe epilepsy.

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    OBJECTIVES: We aimed to 1) determine if subcortical volume deficits are common to mesial temporal lobe epilepsy (MTLE) patients and their unaffected siblings 2) assess the suitability of subcortical volumetric traits as endophenotypes for MTLE. METHODS: MRI-based volume measurements of the hippocampus, amygdala, thalamus, caudate, putamen and pallidium were generated using an automated brain reconstruction method (FreeSurfer) for 101 unrelated 'sporadic' MTLE patients [70 with hippocampal sclerosis (MTLE+HS), 31 with MRI-negative TLE], 83 unaffected full siblings of patients and 86 healthy control subjects. Changes in the volume of subcortical structures in patients and their unaffected siblings were determined by comparison with healthy controls. Narrow sense heritability was estimated ipsilateral and contralateral to the side of seizure activity. RESULTS: MTLE+HS patients displayed significant volume deficits across the hippocampus, amygdala and thalamus ipsilaterally. In addition, volume loss was detected in the putamen bilaterally. These volume deficits were not present in the unaffected siblings of MTLE+HS patients. Ipsilaterally, the heritability estimates were dramatically reduced for the volume of the hippocampus, thalamus and putamen but remained in the expected range for the amygdala. MRI-negative TLE patients and their unaffected siblings showed no significant volume changes across the same structures and heritability estimates were comparable with calculations from a healthy population. CONCLUSIONS: The findings indicate that volume deficits for many subcortical structures in 'sporadic' MTLE+HS are not heritable and likely related to acquired factors. Therefore, they do not represent suitable endophenotypes for MTLE+HS. The findings also support the view that, at a neuroanatomical level, MTLE+HS and MRI-negative TLE represent two distinct forms of MTLE

    A Study of Memetic Search with Multi-parent Combination for UBQP

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    We present a multi-parent hybrid genetic–tabu algorithm (denoted by GTA) for the Unconstrained Binary Quadratic Programming (UBQP) problem, by incorporating tabu search into the framework of genetic algorithm. In this paper, we propose a new multi-parent combination operator for generating offspring solutions. A pool updating strategy based on a quality-and-distance criterion is used to manage the population. Experimental comparisons with leading methods for the UBQP problem on 25 large public instances demonstrate the efficacy of our proposed algorithm in terms of both solution quality and computational efficiency

    Obesity, inflammation and brachial artery flow-mediated dilatation: Therapeutic targets in patients with microvascular angina (Cardiac Syndrome X)

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    Background The pathophysiology of microvascular angina (cardiac syndrome X, CSX), (effort-induced angina, a positive response to exercise stress testing and angiographically normal coronary arteries) has not been fully elucidated. Various pathogenic mechanisms have been proposed, amongst which coronary microvascular dysfunction features prominently. Management of patients with microvascular angina is often challenging as a substantial number of patients does not respond to conventional anti-anginal therapy. In this study, we sought to assess the association between brachial artery FMD, high-sensitive C-reactive protein (hs-CRP) and cardiovascular risk factors including obesity in patients with cardiac syndrome X. Methods and results Thirty-four consecutive CSX patients (29 female, mean age 60 ± 9 years) were recruited from a specialised CSX clinic. Twelve asymptomatic subjects (10 female, mean age 51 ± 12 years) with comparable cardiovascular risk factor profile served as controls. All participants underwent standardized computer-assisted FMD measurements and assessment of hs-CRP concentrations at study entry. Body mass index (BMI), used as a general measure of obesity was calculated as weight (kilograms) divided by height (meters squared). Compared to controls, CSX patients had significantly higher hs-CRP concentrations (p = 0.003) and impaired FMD (p < 0.01). Moreover, among the CSX patients, a correlation between FMD and hs-CRP (r = −0.66, p < 0.01), FMD and BMI (r = 0.377, p = 0.028), and hs-CRP and BMI (r = −0.372, p = 0.030) was found. Conclusion Impaired brachial artery FMD is significantly associated with elevated hs-CRP concentrations and BMI in patients with CSX. The results support the concept that low-grade inflammation and obesity may promote vascular dysfunction in these patients representing therapeutic targets for future research investigations
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