984 resultados para MAGNETICALLY CONFINED PLASMAS
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Thesis (Master's)--University of Washington, 2016-06
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Elongated dust grains exist in astrophysical plasmas. Anisotropic growth of elliptical dust grains, via plasma deposition, occurs if the deposited ions are non-inertial. In reality the extent of such growth depends upon the initial kinetic energy of the ions and the magnitude of the electric field in the sheath. Simulations of the dynamics of the ions in the sheath are reported, showing how elliptical growth is related to the initial eccentricity and size of the seed relative to the sheath length. Consequences for the eventual fate of elliptical dust are then discussed.
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Coronal jets represent important manifestations of ubiquitous solar transients, which may be the source of significant mass and energy input to the upper solar atmosphere and the solar wind. While the energy involved in a jet-like event is smaller than that of “nominal” solar flares and coronal mass ejections (CMEs), jets share many common properties with these phenomena, in particular, the explosive magnetically driven dynamics. Studies of jets could, therefore, provide critical insight for understanding the larger, more complex drivers of the solar activity. On the other side of the size-spectrum, the study of jets could also supply important clues on the physics of transients close or at the limit of the current spatial resolution such as spicules. Furthermore, jet phenomena may hint to basic process for heating the corona and accelerating the solar wind; consequently their study gives us the opportunity to attack a broad range of solar-heliospheric problems.
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The application of stochastic methods to the problem of particle and energy transport in turbulent plasmas is briefly reviewed. The "classical" Corrsin approximation is shown to be valid only in the limit of weak turbulence. The recently developed method of decorrelation trajectories is applicable over the whole range of turbulence intensities and yields the correct asymptotic behavior in the limit of very strong turbulence (subdiffusion). © 2004 Wiley Periodicals, Inc.
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A methodology has been developed and presented to enable the use of small to medium scale acoustic hover facilities for the quantitative measurement of rotor impulsive noise. The methodology was applied to the University of Maryland Acoustic Chamber resulting in accurate measurements of High Speed Impulsive (HSI) noise for rotors running at tip Mach numbers between 0.65 and 0.85 – with accuracy increasing as the tip Mach number was increased. Several factors contributed to the success of this methodology including: • High Speed Impulsive (HSI) noise is characterized by very distinct pulses radiated from the rotor. The pulses radiate high frequency energy – but the energy is contained in short duration time pulses. • The first reflections from these pulses can be tracked (using ray theory) and, through adjustment of the microphone position and suitably applied acoustic treatment at the reflected surface, reduced to small levels. A computer code was developed that automates this process. The code also tracks first bounce reflection timing, making it possible to position the first bounce reflections outside of a measurement window. • Using a rotor with a small number of blades (preferably one) reduces the number of interfering first bounce reflections and generally improves the measured signal fidelity. The methodology will help the gathering of quantitative hovering rotor noise data in less than optimal acoustic facilities and thus enable basic rotorcraft research and rotor blade acoustic design.
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One of the main concerns in the technological application of several metal–organic frameworks (MOFs) relates to their structural instability under pressure (after a conforming step). Here we report for the first time that mechanical instability can be highly improved via nucleation and growth of MOF nanocrystals in the confined nanospace of activated carbons.
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Leg ulcers represent a particularly disabling complication in patients with sickle cell disease (SCD). Platelet gel (PG) is a novel therapeutic strategy used for accelerating wound healing of a wide range of tissues through the continuous release of platelet growth factors. Here, we describe the use of PG preparation according to Anitua's PRGF (preparations rich in growth factors) protocol for treating chronic nonhealing ulcers in patients with SCD. A positive response occurred in 3 patients with an area reduction of 85.7% to 100%, which occurred within 7 to 10 weeks, and a 35.2% and 20.5% of area reduction in 2 other patients, who however, had large ulcers. After calcium chloride addition, the platelet-rich plasmas demonstrated enhanced platelet-derived growth factors-BB (P < .001), transforming growth factor-β1 (P = .015), vascular endothelial growth factors (P = .03), and hepatocyte growth factors (nonsignificant) secretion. Furthermore, calcium chloride addition induced a significant decrease in platelet number (P = .0134) and there was no leukocyte detection in the PG product. These results demonstrate that PG treatment might impact the healing of leg ulcers in sickle cell disease, especially in patients with small ulcers.
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In the Amazon Region, there is a virtual absence of severe malaria and few fatal cases of naturally occurring Plasmodium falciparum infections; this presents an intriguing and underexplored area of research. In addition to the rapid access of infected persons to effective treatment, one cause of this phenomenon might be the recognition of cytoadherent variant proteins on the infected red blood cell (IRBC) surface, including the var gene encoded P. falciparum erythrocyte membrane protein 1. In order to establish a link between cytoadherence, IRBC surface antibody recognition and the presence or absence of malaria symptoms, we phenotype-selected four Amazonian P. falciparum isolates and the laboratory strain 3D7 for their cytoadherence to CD36 and ICAM1 expressed on CHO cells. We then mapped the dominantly expressed var transcripts and tested whether antibodies from symptomatic or asymptomatic infections showed a differential recognition of the IRBC surface. As controls, the 3D7 lineages expressing severe disease-associated phenotypes were used. We showed that there was no profound difference between the frequency and intensity of antibody recognition of the IRBC-exposed P. falciparum proteins in symptomatic vs. asymptomatic infections. The 3D7 lineages, which expressed severe malaria-associated phenotypes, were strongly recognised by most, but not all plasmas, meaning that the recognition of these phenotypes is frequent in asymptomatic carriers, but is not necessarily a prerequisite to staying free of symptoms.
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Central nervous system involvement in Candida septicaemia is rare and not more than four cases have been published in Brazil. Five new cases of systemic candidiasis with cerebral lesions are reported. All patients (four adults and a child) had serious underlying diseases and were submitted to heavy long-term antibiotic therapy with multiple drugs. Seizures in one case and neck stiffness in another were the only neurologic signs that could be attributed to candidiasis. In no case were the lesions severe enough to be considered an immediate cause of death. In three patients, no macroscopic changes were evident in the brain, but microabscesses and granulomata were observed on microscopical examination; another patient had two gross areas with necrotic and haemorrhagic appearance in the cerebral hemispheres; the child had only two microscopic granulomata. The aetiological agent was demonstrated by Grocott's methenamine silver technique in all cases. Involvement of organs other than the central nervous system could be demonstrated in three autopsies. Discussion is confined mainly to such aspects as the contributory factors in the pathogenesis of systemic candidiasis as well as the marked rise in the incidence of this condition in the past few decades. It is suggested that the frequence of monilial septicaemia in Brazil may be far more serious than apparent from the scarcity of reported cases.
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Universidade Estadual de Campinas . Faculdade de Educação Física
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We have considered a Bose gas in an anisotropic potential. Applying the the Gross-Pitaevskii Equation (GPE) for a confined dilute atomic gas, we have used the methods of optimized perturbation theory and self-similar root approximants, to obtain an analytical formula for the critical number of particles as a function of the anisotropy parameter for the potential. The spectrum of the GPE is also discussed.
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The thermal conductivity and mechanical strength of gypsum and gypsum-cellulose plates made from commercial plaster by a new process have been measured. The gypsum parts made by the new process, 'novogesso', have high mechanical strength and low porosity. The gypsum strength derives from both the high aspect ratio of the gypsum crystals and the strong adhesion among them by nano-flat layers of confined water, which behaves as supercooled water. Another contribution to the strength comes from the nano-flatness of the lateral surfaces of the gypsum single crystals. The bending and compression strengths, σB and σc, of gypsum plates prepared by this new technique can be as high as 30 and 100 MPa, respectively. The way gypsum plates have been assembled as well as their low thermal conductivity allowed for the construction of a low-cost experimental house with thermal and acoustic comfort.
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INTRODUÇÃO: A tuberculose sempre foi um grave problema de saúde para grupos de pessoas confinadas, especialmente em presídios, devido à sua transmissão respiratória. OBJETIVO: Verificar a associação entre o tempo de prisão e a taxa de infecção tuberculosa na população carcerária dos Distritos Policiais da zona oeste da cidade de São Paulo. METODOLOGIA:Foi realizado um estudo observacional, no período de março de 2000 a maio de 2001, com a aplicação de um inquérito individual e da prova tuberculínica (PPD-RT23 - 2UT/0.1ml) nos detentos. RESULTADOS E DISCUSSÃO: Do total de 1.052 presos entrevistados, 932 concordaram em fazer a prova tuberculínica e, destes, 64,5% estavam infectados. Para as análises, os detentos foram classificados como primários e reincidentes e como não reatores e reatores à prova tuberculínica, segundo o tempo de prisão. Entre os 134 detentos primários que estavam presos há menos de 60 dias, 40,3% foram reatores ao PPD e dos 53 com mais de 366 dias de prisão a percentagem de reatores foi de 62,3%. Entre os 146 detentos reincidentes presos há menos de 60 dias, 72,6% foram reatores ao PPD e dos 25 com mais de 366 dias de prisão, 100,0% estava infectado. Em todos os períodos de permanência na prisão, os detentos reincidentes tiveram maior percentagem de infecção tuberculosa do que os detentos primários. A associação entre tempo de prisão e reatividade ao PPD foi confirmada pelo Teste de Tendência (p<0.001) do programa Epi-Info-6. CONCLUSÕES:Quanto maior o tempo de prisão, maior a taxa de infecção tuberculosa. Detentos reincidentes são um risco de infecção para os detentos primários.