492 research outputs found

    Effects of Combined Ezetimibe and Simvastatin Therapy as Compared With Simvastatin Alone in Patients With Type 2 Diabetes: A Prospective Randomized Double-Blind Clinical Trial Response to Sarigianni, Katsiki, and Mikhailidis

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    Sarigianni et al. (1) properly pointed out that in the Ezetimibe and Simvastatin in dyslipidemia of Diabetes (ESD) randomized clinical trial "the serum HDL cholesterol was significantly lower after adding ezetimibe compared with simvastatin monotherapy." The concomitant reduction in LDL cholesterol observed during simvastatin and ezetimibe combination therapy, however, exceeded the decrease in HDL cholesterol (2). Consequently, the LDL-to-HDL cholesterol ratio decreased from (mean ± SD) 2.11 ± 0.64 at randomization

    Numerical steady-state and transient responses of a SDOF system constrained by two optimally designed bumpers

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    Seismically isolated structures can be subjected to large horizontal displacements relative to the ground, especially in Near-Fault earthquakes, which are characterized by one or more intense pulses of velocity and displacement of long period. One strategy to mitigate the problem of large displacements, which occurs in linearly isolated structures, is the use of deformable and dissipative devices (bumpers). The impact between the structure and the bumpers, if the bumpers are appropriately designed, can produce beneficial effects on the dynamic response of the system, both on displacements and accelerations. In this paper the response obtained from a numerical model of isolated single-degree-of-freedom (SDOF) systems constrained by two bumpers, arranged symmetrically on both sides of the mass of the system with an initial gap, subjected to base harmonic excitation, is studied. This model is called Vibro-Impact Isolation System (V-IIS). The objective of this work is to define a methodology for choosing the design parameter defining the V-IIS (mechanical characteristics of the bumpers, gap and isolation frequency of the system) by observing both steady-state and transient responses of both the system and the bumpers. The study of the transient response is compared with that obtained in the steady-state to assess how representative the latter is of the V-IIS transient response. From the definition of the methodology for choosing the parameters of the V-IIS, through optimal design, the only design parameters are the gap and the isolation frequency of the system. Therefore, an appropriate choice of the gap makes it possible to bring frequency-selective viscous damping in V-IISs, introducing two advantages over linear systems: the reduction of the peak intensity of the responses in the resonance range (both displacement and acceleration) and the reduction of the static displacement of the system, but keeping the dynamic response with which the system is designed unchanged

    Performance Assessment of Different Roof Integrated Photovoltaic Modules under Mediterranean Climate

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    AbstractMany countries, for aesthetic purposes, offer economic advantages (tax deductions, incentives, etc..) for the installation of building integrated photovoltaic modules (BIPV), with water-tightness capability and adequate mechanical resistance in order to substitute tile covering or part of it. Nevertheless, poor or absent ventilation under BIPV panels could cause them to overheat and reduce their efficiency.It is well established that the presence of an air gap between a photovoltaic (PV) module and roof covering facilitates ventilation cooling under the device and consequently reduces cell temperature and improves its performance.In this study, we investigated the thermal performance of PV modules installed in a real scale experimental building over a traditional clay tile pitched roof in Italy for almost one year (from August 2009 to June 2010). One PV module was rack-mounted over the roof covering with a 0.2 m air gap; the others were fully integrated and installed at the same level of the roof covering (one with an air gap of 0.04 m, the other mounted directly in contact with the insulation). Temperature and heat flux measurements for each panel, and environmental parameters were recorded.Experimental results demonstrate that even though the rack-mounted PV module constantly maintains cell temperature below that of the other full-building integrated modules, due to the presence of a higher air gap, the difference in the energy produced by the PV modules estimated for the entire monitoring period is less than 4%

    Scale-independent roughness value of cell membranes studied by means of AFM technique

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    AbstractThe roughness of cell membrane is a very interesting indicator of cell's health state. Atomic Force Microscopy allows us to investigate the roughness of cell membrane in great detail, but the obtained roughness value is scale-dependent, i.e. it strongly depends on measurement parameters, as scanning area and step size. The scale-dependence of the roughness value can be reduced by means of data filtration techniques, that are not standardized at nanometric scale, especially as far as biological data are concerned. In this work, a new method, based on the changes of values of some roughness parameter (root mean square roughness and skewness) as a function of filtration frequencies, has been implemented to optimize data filtering procedure in the calculation of cell membrane roughness. In this way, a root mean square roughness value independent of cell shape, membrane micro-irregularities and measurement parameters can be obtained. Moreover, different filtration frequencies selected with this method allow us to discriminate different surface regimes (nominal form, waviness and roughness) belonging to the raw cell profile, each one related to different features of the cell surface

    Reflectance and photoluminescence characterization of CdS and CdSe heteroepitaxial films deposited by laser ablation technique

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    Optical properties of CdSe and CdS films, deposited on sapphire substrate by means of pulsed laser ablation technique, have been investigated in order to study the effect of such a transparent substrate on the photoluminescence efficiency of the deposited epilayers. CdSe and CdS films present intrinsic (excitonic) emission at low temperature, differently from the same films deposited on quartz. The temperature dependence of the excitonic energy has been analyzed taking into account the contribution of both the thermal dilatation and electron-phonon interaction
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