Search results for "COMPRESSION"
showing 10 items of 774 documents
Characteristics and treatment of Multiple Sclerosis-related trigeminal neuralgia: An Italian multi-centre study
2019
Abstract Background The prevalence of trigeminal neuralgia (TN) in Multiple Sclerosis (MS) patients is higher than in the general population and its management can be particularly challenging. Our aim is to describe the characteristics, treatment and prognostic factors of MS-related TN in a retrospective multicentre study. Methods Neurologists members of the RIREMS group (Rising Researchers in MS) enrolled MS patients with a TN diagnosis and filled out a spreadsheet comprising their clinical data. Results Population consisted of 298 patients. First-choice preventive treatments were carbamazepine and oxcarbazepine. A surgical procedure was performed in 81 (30%) patients, most commonly gamma …
Bending or buckling: Compression-induced phase transition in a semi-flexible polymer brush
2013
Molecular-dynamics simulations are presented for systems of densely grafted semiflexible macromolecules grafted to a planar non-adsorbing substrate, studying the case where the persistence length of the polymers is of the same order as their contour length so that the polymer brush may exhibit nematic order. We focus our attention on the case where the first bond must orient perpendicularly to the substrate (so the structure resembles a "Fakir's bed" for short chains and a "polymer bristle" for longer chains). When such layers are exposed to uniform compression, the pressure vs. distance relationship exhibits two stages: i) for very small compression the chains exhibit "buckling" yet mainta…
Der Einflu� einer ven�sen Stauung im Kopfbereich auf die Wasser- und Elektrolytausscheidung von Ratten
1960
1. Salt and water retention can be produced in rats by compression in the neck region or by ligature of the jugular veins.
Medidas de Tromboprofilaxis en Artroplastia Total de Rodilla. Práctica habitual en la Comunidad Valenciana y revisión bibliográfica.
2020
espanolAntecedentes: El tromboembolismo es una complicacion de la cirugia de artroplastia total de rodilla. Para su prevencion disponemos de multiples medidas fisicas y farmacologicas.Objetivo:Conocer quemedidas de prevencion tromboembolica son las empleadas por los cirujanos ortopedicos en cirugia protesica de rodilla primaria en diferentes centros hospitalarios de nuestra region.Metodo: Estudio transversal descriptivo observacional basado en encuesta dirigida a especialistas COT de 9 hospitales publicos de la Comunidad Valenciana y busqueda bibliografica.Resultados: Se obtuvieron 64 encuestas. Todos los cirujanos eligen HBPM durante un mes como medida de tromboprofilaxis, descartando anti…
Characterization and Decomposition of the Natural van der Waals SnSb2Te4 under Compression
2020
[EN] High pressure X-ray diffraction, Raman scattering, and electrical measurements, together with theoretical calculations, which include the analysis of the topological electron density and electronic localization function, evidence the presence of an isostructural phase transition around 2 GPa, a Fermi resonance around 3.5 GPa, and a pressure-induced decomposition of SnSb2Te4 into the high-pressure phases of its parent binary compounds (alpha-Sb2Te3 and SnTe) above 7 GPa. The internal polyhedral compressibility, the behavior of the Raman-active modes, the electrical behavior, and the nature of its different bonds under compression have been discussed and compared with their parent binary…
Comment on “Molybdenum sound velocity and shear modulus softening under shock compression”
2015
In this Comment we discuss recent results presented by Nguyen et al. on shock compressed molybdenum up to 438 GPa [Phys. Rev. B 89, 174109 (2014)]. The aim of Nguyen's article is to show that there is no phase transition near 210 GPa. We propose instead an interpretation of their data that this material shows the onset of partial melting along the Hugoniot at $240(20)\phantom{\rule{0.28em}{0ex}}\mathrm{GPa}$, which is evident from abrupt changes in the pressure dependence of the shear modulus. This interpretation may solve the significant controversy in the melting slopes derived from shock and static experiments.
Optical measurements of an acylated azacrown at the air-water interface
1991
In this study, a cyclame derivative bearing four aliphatic chain substituents shows, like many amphiphiles, solid-condensed as well as liquid-expanded phases. In contrast to the classical amphiphiles, the onset of its phase transition is characterized by a bump-like shape whose amplitude is a function of the compression speed. Ellipsometry which is very sensitive to the monolayer physical state changes, and fluorescence microscopy which has contributed significantly to the understanding of the phenomena occurring in the phase transition region have been used to investigate the monolayer behavior of this compound. This study shows that in the liquid-expanded state, the film is homogeneous an…
Experimental and Theoretical Study of SbPO 4 under Compression
2019
SbPO4 is a complex monoclinic layered material characterized by a strong activity of the non-bonding lone electron pair (LEP) of Sb. The strong cation LEP leads to the formation of layers piled up along the a-axis and linked by weak Sb-O electrostatic interactions. In fact, Sb is 4-fold coordination with O similar to what occurs with the P-O coordination, despite the large difference of ionic radii and electronegativity between both elements. Here we report a joint experimental and theoretical study of the structural and vibrational properties of SbPO4 at high pressure. We show that SbPO4 is not only one of the most compressible phosphates but also one of the most compressible compounds of …
Cathodoluminescence and photoluminescence study of plastically deformed ZnTe bulk single crystals
2001
Samples of zinc telluride bulk single crystals, which were deformed in uniaxial compression, have been studied by photoluminescence (PL) and cathodoluminescence (CL). As a particular feature the deformed samples present a PL emission band peaked at 603 nm, whose intensity increases as the plastic deformation does. This band is related to the density of dislocations produced during the interaction of slip systems. This hypothesis is supported by CL images. which reveal the activation of the successive slip systems corresponding to different levels of deformation.
On the Rigorous Calculation of All Ohmic Losses in Rectangular Waveguide Multi-Port Junctions
2005
In this paper, all ohmic losses effects present in rectangular waveguide multi-port junctions are rigorous and efficiently computed. For this purpose, a new formulation based on the theory of cavities, which provides generalized admittance matrix representations for such junctions, is proposed. To validate this theory, we have successfully compared our results with numerical data of a lossy E-plane T-junction and of a hollow waveguide, as well as with experimental measurements of a real H-plane T-junction.