3,211 research outputs found

    Effects of a trapped vortex cell on thick wing profile

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    Experimental investigation on the effects originated from a trapped vortex cell on the NACA0024 airfoi

    Effects of thickness on the spin susceptibility of the 2D electron gas

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    Using available quantum Monte Carlo predictions for a strictly 2D electron gas, we have estimated the spin susceptibility of electrons in actual devices taking into account the effect of the finite transverse thickness and finding a very good agreement with experiments. A weak disorder, as found in very clean devices and/or at densities not too low, just brings about a minor enhancement of the susceptibility.Comment: 4 pages, 3 figure

    Quadriexcitons and excitonic condensate in a symmetric electron-hole bilayer with valley degeneracy

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    Using quantum Monte Carlo simulations we have mapped out the zero temperature phase diagram of a symmetric electron-hole bilayer with twofold valley degeneracy, as function of the interlayer distance dd and in-layer density nn. We find that the effect of the valley degeneracy is to shrink the region of stability of the excitonic condensate, in favor of quadriexcitons at small dd and of the four-component plasma at large dd, with minor effects on the value of the excitonic condensate fraction. The enclosure of the condensate in a density window possibly explains why anomalous tunnelling conductivity, interpreted as signature of condensation, is observed only between two finite values of carrier density in graphene bilayers. Our phase diagram may provide directions to select device parameters for future experiments.Comment: paper: 5 pages and 4 figures; supplemental info: 5 pages, 7 figures, 2 table

    Early impairment of endothelial structure and function in young normal-weight women with polycystic ovary syndrome

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    The aim of this study was to evaluate the presence of early vascular damage in young normal-weight women with polycystic ovary syndrome (PCOS).Thirty young normal-weight women with PCOS, who had no additional metabolic or cardiovascular diseases, and 30 healthy women (controls) matched for age and body mass index were studied. A complete hormonal assay was performed in each subject. Serum insulin and glucose levels were measured at baseline and after the oral glucose tolerance test. Plasma endothelin-1 levels and serum lipid profile were also assessed. The endothelial function was studied by flow-mediated dilation on the brachial artery, and arterial structure was evaluated by intima-media thickness measurement using Doppler ultrasound of both common carotid arteries.A significant (P < 0.05) difference in flow-mediated dilation (14.3 +/- 1.9% vs. 18.1 +/- 2.0% for PCOS patients and controls, respectively) and in intima-media thickness (0.53 +/- 0.09 mm vs. 0.39 +/- 0.08 mm for PCOS patients and controls, respectively) was found between PCOS and control subjects. Serum endothelin-1 levels were also significantly (P < 0.05) higher in PCOS patients compared with controls (1.1 +/- 0.4 pmol/liter vs. 0.5 +/- 0.2 pmol/liter for PCOS patients and controls, respectively).In conclusion, our data show that young, normal-weight, nondyslipidemic, nonhypertensive women with PCOS have an early impairment of endothelial structure and function

    An Advanced Pavement Management System based on a Genetic Algorithm for a Motorway Network

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    Maintenance and improvement, through the rehabilitation, of the road infrastructure is a strategic and priority objective for road agencies, nevertheless the economic resources required are often inadequate. Within road management, the pavement management system (PMS) plays an essential role because of both the money needed and the performance that should be provided in terms of safety, ride quality and transport cost. The PMS is based on searching for a balanced solution between the lowest cost and the increased level of performance (i.e. pavement condition). In this paper a PMS multi-objective optimization method, was proposed, using a genetic algorithm (GA) to identify the best solution considering different rehabilitation strategies. The multi-objective optimization GA permits a set of optimal solutions (the Pareto solution set) that takes into account all the considered constraints. Finally on the basis of a specific criteria the best solution was selected in relation to the ranking of the priorities of the agency. A detailed numerical study was conducted on the Italian A18 motorway and the results showed that the proposed model PMS-GA is a suitable support to the decision making process

    Cognitive reserve index and functional and cognitive outcomes in severe acquired brain injury: A pilot study

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    Background: Many variables affect outcome after brain injury. Cognitive reserve (CR) is a subjective factor that reflects a set of personal characteristics and that differentiates individuals. It may influence an individual’s capacity to react to brain injury. Objective: To study the effects of cognitive reserve on functional and cognitive outcome at the end of rehabilitation, in patients with severe acquired brain injury (sABI), by means of the Cognitive Reserve Index questionnaire (CRIq). Methods: We report a retrospective study of a continuous series of sABI patients on first admission to a rehabilitation center. Disability and cognitive outcomes were recorded. Results: In the 94 patients enrolled, the assessments after rehabilitation showed a significant gain measured with the disability Rating Scale for patients with a higher CR (CRIq≥ 85). A significant negative correlation was found: between CRIq scores and the interval elapsing before first access to neuropsychological assessment, between CRIq scores, especially level of education, and tests that measure the same domain (attention). Conclusions: Improvements in overall and cognitive disability emerged, but CR did not seem to substantially influence outcome in this sample of patients. This result may be partly due to the clinical severity of the population studied and the sample’s dimension, although quantitatively representative of the population

    Matrix Models, Argyres-Douglas singularities and double scaling limits

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    We construct an N=1 theory with gauge group U(nN) and degree n+1 tree level superpotential whose matrix model spectral curve develops an A_{n+1} Argyres-Douglas singularity. We evaluate the coupling constants of the low-energy U(1)^n theory and show that the large N expansion is singular at the Argyres-Douglas points. Nevertheless, it is possible to define appropriate double scaling limits which are conjectured to yield four dimensional non-critical string theories as proposed by Ferrari. In the Argyres-Douglas limit the n-cut spectral curve degenerates into a solution with n/2 cuts for even n and (n+1)/2 cuts for odd n.Comment: 31 pages, 1 figure; the expression of the superpotential has been corrected and the calculation of the coupling constants of the low-energy theory has been adde

    Design and 3D printing of a modular phantom of a uterus for medical device validation

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    PurposeThe purpose of this study is to describe the design and validation of a three-dimensional (3D)-printed phantom of a uterus to support the development of uterine balloon tamponade devices conceived to stop post-partum haemorrhages (PPHs). Design/methodology/approachThe phantom 3D model is generated by analysing the main requirements for validating uterine balloon tamponade devices. A modular approach is implemented to guarantee that the phantom allows testing these devices under multiple working conditions. Once finalised the design, the phantom effectiveness is validated experimentally. FindingsThe modular phantom allows performing the required measurements for testing the performance of devices designed to stop PPH. Social implicationsPPH is the leading obstetric cause of maternal death worldwide, mainly in low- and middle-income countries. The proposed phantom could speed up and optimise the design and validation of devices for PPH treatment, reducing the maternal mortality ratio. Originality/valueTo the best of the authors' knowledge, the 3D-printed phantom represents the first example of a modular, flexible and transparent uterus model. It can be used to validate and perform usability tests of medical devices
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