177,527 research outputs found
NEW DATA ON THE NOMINATIVE SUBGENUS OF THE GENUS MACROSIPHONIELLA DEL GUERCIO, 1911 (HEMIPTERA: APHIDIDAE) FROM PALAEARCTIC
No full textKadyrbekov, R. Kh. (2019): NEW DATA ON THE NOMINATIVE SUBGENUS OF THE GENUS MACROSIPHONIELLA DEL GUERCIO, 1911 (HEMIPTERA: APHIDIDAE) FROM PALAEARCTIC. Far Eastern Entomologist 388: 1-15, DOI: 10.25221/fee.388.1, URL: http://dx.doi.org/10.25221/fee.388.
[Nifedipine and essential arterial hypertension refractory to hypotensive therapy: results of a preliminary double-blind study]
No full text[Electrocardiographic changes in myocardial damage; effect of treatment with nifedipine]
No full textL’organizzazione e la tutela nel tempo delle informazioni digitali: la direzione dell’evoluzione negli standard italiani ed internazionali
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Chronic venous insufficiency, edema and the permeability of the microvascular barrier
No full textMany hypotheses have been proposed to explain the clinical features and laboratory findings during chronic venous insufficiency (CVI). Edema is known to occur primarily as a result of the increase in venous pressure, accompanied by increased capillary permeability (PerM) and decreased blood colloid osmotic pressure as contributing factors. Nevertheless, there are many clinical and experimental observations which are not consistent with this accepted suggestion. Therefore, the diagnosis of edema is formulated, when edema has already occurred, i.e. only when the collection of the fluid exceeds a certain threshold and becomes clinically or instrumentally evident. The aim of this review was to clarify the pathophysiology of venous edema studying two fundamental processes: filtration and absorption that oversee the balance of intra- and extracellular fluids. In particular, we have described the alterations between filtration and absorption. The mechanisms involved in the CVI are several, starting from the structural rearrangement of the vascular endothelium up to the changes in intra and extracellular fluid. Evaluating the previous studies, we hypothesize that the venous edema is produced by the hydrostatic pressure prevailing on blood oncotic pressure, while the "intermediary" system or transduction system must be able to transform the physical stimulus induced by hypertension in a biochemical message promoting the cellular responses. Moreover, the chronic increase in shear stress, characteristic in CVI, prevails on calcium dependent mechanism, resulting in either hypertension, a mechanical stress, abolishes the Ca++ linked mechanism inducing a stable disassembly of adherens junction, or in the long run, the same mechanisms are unable to preserve the barrier integrity with a profound alteration of the vessel wall PerM, accompanied by leakage of macromolecules and blood cells. In conclusion, it is possible to assume that the essential sign in the venous chronic insufficiencies is not the edema, and then an excess of filtration, but the vessel wall permeation is the key factor to clarify the pathophysiological cascade and the clinical signs
SPH simulation of periodic wave breaking in the surf zone - A detailed fluid dynamic validation
No full textThe estimation of wave breaking and run-up on sloped beaches is a relevant issue in different coastal engineering applications. The present study stresses on the capabilities of a Smoothed Particle Hydrodynamics (SPH) solver, with optimal numerical and physical parameters, to accurately simulate the complex flow field in the surf zone and run-up region. Numerical results are compared with high quality experimental measurements of the local flow field in terms of instantaneous and phase averaged values. The selected test case regards the propagation and breaking of regular non-linear waves on a smooth impermeable plane slope. The comparison is based on a complete set of 128 consecutive non-linear regular waves. The level of accuracy of the numerical results and the ability of the model to reproduce the periodic flow in the surf-zone is provided. Current limitations and uncertainty sources are identified and discussed to guide future developments
Numerical modeling of breaking periodical waves on a sloped beach profile by SPH
No full textResults from a systematic verification and validation of Smoothed Particles Hydrodynamic methods for the numerical simulation of periodic breaking water waves on constant sloped beaches are presented. Periodic waves are generated in deep water and then numerically followed during their propagation in constant bottom depth and their transformation up to the breaking and run-up on a sloped beach profile, in a 2D numerical flume wave tank. We verify the consistency of the method first in the simpler case of deep water second order Stokes water waves generated with a flapped type wave-maker, investigating the effect of a number of tuning parameters of the SPH method like artificial viscosity and smoothing length, among others. Once these parameters have been set to ensure the correct reproduction of the kinematic properties of the generated waves the numerical model is then validated in shallow water, following their transformation on a constant slope bottom. Numerical results are compared with experimental ones in terms of wave profiles and flow field characteristics at different longitudinal location along the sloped beach taken. Copyright © 2014 by the International Society of Offshore and Polar Engineers (ISOPE)
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