Search results for "VOLUME"
showing 10 items of 1932 documents
Left ventricular hypertrophy or storage disease? the incremental value of speckle tracking strain bull's-eye
2017
Left ventricular hypertrophy (LVH) develops in response to a variety of physical, genetic, and biochemical stimuli and represents the early stage of ventricular remodeling. In patients with LVH, subclinical left ventricular (LV) dysfunction despite normal ejection fraction (EF) may be present before the onset of symptoms, which portends a dismal prognosis. Strain measurement with two-dimensional speckle tracking echocardiography (STE) represents a highly reproducible and accurate alternative to LVEF determination. The present review focuses on current available evidence that supports the incremental value of STE in the diagnostic and prognostic workup of LVH. When assessing the components o…
Number, Mass and Volume Distributions of Mineral Aerosol and Soils of the Sahara
1983
Abstract A direct method will be described to determine the complete mineral size distribution in aerosol (xylene-insoluble component) and soils (water-insoluble component) covering a size range from 0.01 up to 100 μm and 1000 μm radius, respectively, by using a combination of a scanning electron microscope, optical microscope and sieving. Aerosol and soil samples from the Sahara have been investigated. All mineral aerosol size distributions indicate a maximum between 0.06 and 0.08 μm radius and mineral particles have been found in the Aitken size range down to 0.02 μm radius. The concentration decrease toward larger particles is not uniform and shows considerable variations below 0.5 μm an…
Raman scattering in hcp rare gas solids under pressure
2008
We present Raman measurements of hcp rare gas solids (RGSs) at megabar pressures together with lattice dynamics calculations. The ${E}_{2g}$ phonon was measured in Xe up to metallization near 135 GPa and in Ar up to 58 GPa. A comparative analysis of first-principles and semiempirical calculations shows that three-body forces contribute to the energetics at low pressures and that at volume compressions greater than $\ensuremath{\sim}2.6$ higher-order many-body forces become important. The distinct behavior of He under pressure relative to that of the rest of the RGS family is discussed.
Assisted self-sustaining combustion reaction in the Fe–Si system: Mechanical and chemical activation
2007
Abstract This work presents original investigations carried out to improve the activated self-propagating high-temperature synthesis (SHS) process in the Fe–Si system: different ignition modes are tested (volume heating as opposed to a local ignition source), and the use of additive is considered in order to enhance the SHS type reactivity in the Fe–Si system. When 20 wt.% of KNO 3 is added to the reactive mixture, the fast (>20 mm s −1 ), stable and self-sustaining combustion reaction produces a very fine FeSi + α-FeSi 2 structure. Infrared thermography (IR) as well as post-mortem analysis (SEM, EDXS, XRD) was used to understand the mechanism behind the chemical activation process when KNO…
Progressive right ventricular dysfunction and exercise impairment in patients with heart failure and diabetes mellitus: insights from the T.O.S.CA. R…
2022
Abstract Background Findings from the T.O.S.CA. Registry recently reported that patients with concomitant chronic heart failure (CHF) and impairment of insulin axis (either insulin resistance—IR or diabetes mellitus—T2D) display increased morbidity and mortality. However, little information is available on the relative impact of IR and T2D on cardiac structure and function, cardiopulmonary performance, and their longitudinal changes in CHF. Methods Patients enrolled in the T.O.S.CA. Registry performed echocardiography and cardiopulmonary exercise test at baseline and at a patient-average follow-up of 36 months. Patients were divided into three groups based on the degree of insulin impairmen…
Water dynamics in different biochar fractions
2015
Biochar is a carbonaceous porous material deliberately applied to soil to improve its fertility. The mechanisms through which biochar acts on fertility are still poorly understood. The effect of biochar texture size on water dynamics was investigated here in order to provide information to address future research on nutrient mobility towards plant roots as biochar is applied as soil amendment. A poplar biochar has been stainless steel fractionated in three different textured fractions (1.0–2.0 mm, 0.3–1.0 mm and <0.3 mm, respectively). Water-saturated fractions were analyzed by fast field cycling (FFC) NMR relaxometry. Results proved that 3D exchange between bound and bulk water predominant…
L'utilisation des reliefs naturels dans l'art gravé et sculpté pariétal du paléolithique supérieur français
2005
Pendant toute la durée du Paléolithique supérieur, en Espagne et en France principalement, les artistes ont réalisé des figurations en utilisant les reliefs naturels et la morphologie des parois de grottes ou d'abris-sous-roche. Ce phénomène artistique, qui a toujours préoccupé les préhistoriens, a suscité les interrogations et les interprétations les plus diverses de la fin du XIXe siècle jusqu'à présent : origine de l'art, préoccupations magico-religieuses, organisation spatiale et sanctuarisation de l'espace souterrain, structures pariétales, chamanisme, techno-cultures, etc. Pendant longtemps, ce que les formes rocheuses pouvaient avoir d'évocateur a été considéré comme la raison d'être…
A Positive Definite Advection Scheme Obtained by Nonlinear Renormalization of the Advective Fluxes
1989
Abstract A new method is developed to obtain a conservative and positive definite advection scheme that produces only small numerical diffusion. Advective fluxes are computed utilizing the integrated flux form of Tremback et al. These fluxes are normalized and then limited by upper and lower values. The resulting advection equation is numerically solved by means of the usual upstream procedure. The proposed treatment is not restricted to the integrated flux form but may also be applied to other known advection algorithms which are formulated in terms of advective fluxes. Different numerical tests are presented illustrating that the proposed scheme strongly reduces numerical and diffusion an…
Surgeon volume and hospital volume in endocrine neck surgery: how many procedures are needed for reaching a safety level and acceptable costs? A syst…
2018
The relationship between quality of care and provider's experience is well known in all fields of surgery. Even in thyroidectomies and parathyroidectomies, the emphasis on positive volume-outcome relationships is believed. It led us to an evaluation of volume activity's impact in terms of quality of care. A systematic narrative review was performed. According to the PRISMA criteria, we selected 87 paper and, after the study selection was performed, 22 studies were finally included in this review. All articles included were unanimous in attributing to activity volume of surgeons as well as centers a substantial importance. Some differences in outcomes between these investigated categories ha…
Laparoscopic distal pancreatectomy in Italy: A systematic review and meta-analysis.
2014
BACKGROUND: The use of laparoscopic distal pancreatectomy (LDP) increased in the past twenty years but the real diffusion of this technique is still unknown as well as the type of centers (high or low volume) in which this procedure is more frequently performed. DATA SOURCE: A systematic review was performed to evaluate the frequency of LDP in Italy and to compare indications and results in high volume centers (HVCs) and in low volume centers (LVCs). RESULTS: From 95 potentially relevant citations identified, only 5 studies were included. A total of 125 subjects were analyzed, of whom 95 (76.0%) were from HVCs and 30 (24.0%) from LVCs. The mean number of LDPs performed per year was 6.5. The…