996 resultados para TORSION ANGLE
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As maloclusões estão sempre presente em nossa pratica clínica, por isso é importante a prevenção das causas dessas maloclusões. Os transtornos dos hábitos podem aparecer nas diferentes maloclusões de Angle, Esses transtornos de hábitos podem ser causadores de maloclusões e evidenciar o tipo do padrão facial. O objetivo dessa pesquisa foi de analisar se a relação nos transtorna dos hábitos com as maloclusões de Angle e o tipo facial. A amostra foi composta por 398 pacientes com média de idade de 13 anos e 3 meses. De acordo com os resultados encontrados pode-se concluir que: Não houve associação estatisticamente significante entre o tipo de maloclusão e o tipo de amamentação; Não houve associação estatisticamente significante entre o tipo de maloclusão e a sucção de dedo ou de chupeta; Não houve associação estatisticamente significante entre o tipo facial e tipo de amamentação; Não houve associação estatisticamente significante entre tipo facial e o hábito de sucção de chupeta; Na associação de entre o tempo do hábito de sucção e tipo facial,houve maior freqüência deste hábito no tipo dolicofacial;Não houve associação estatisticamente entre o tempo dos hábitos e maloclusão; O tempo de sucção de chupeta foi maoir em braquifacial em relação dolicofacial.(AU)
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As maloclusões estão sempre presente em nossa pratica clínica, por isso é importante a prevenção das causas dessas maloclusões. Os transtornos dos hábitos podem aparecer nas diferentes maloclusões de Angle, Esses transtornos de hábitos podem ser causadores de maloclusões e evidenciar o tipo do padrão facial. O objetivo dessa pesquisa foi de analisar se a relação nos transtorna dos hábitos com as maloclusões de Angle e o tipo facial. A amostra foi composta por 398 pacientes com média de idade de 13 anos e 3 meses. De acordo com os resultados encontrados pode-se concluir que: Não houve associação estatisticamente significante entre o tipo de maloclusão e o tipo de amamentação; Não houve associação estatisticamente significante entre o tipo de maloclusão e a sucção de dedo ou de chupeta; Não houve associação estatisticamente significante entre o tipo facial e tipo de amamentação; Não houve associação estatisticamente significante entre tipo facial e o hábito de sucção de chupeta; Na associação de entre o tempo do hábito de sucção e tipo facial,houve maior freqüência deste hábito no tipo dolicofacial;Não houve associação estatisticamente entre o tempo dos hábitos e maloclusão; O tempo de sucção de chupeta foi maoir em braquifacial em relação dolicofacial.(AU)
The lipid bilayer determines helical tilt angle and function in lactose permease of Escherichia coli
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The structure of lactose permease from Escherichia coli in its lipid environment was studied by attenuated total reflection Fourier transform infrared spectroscopy. The protein exhibits an α-helical content of about 65% and about 25% β-sheet. Unusually fast hydrogen/deuterium (H/D) exchange to 90–95% completion suggests a structure that is highly accessible to the aqueous phase. An average tilt angle of 33° for the helices was found with respect to the bilayer normal at a lipid-to-protein ratio of ≈800:1 (mol/mol), and the permease exhibits optimal activity under these conditions. However, upon decreasing the lipid-to-protein ratio, activity decreases continuously in a manner that correlates with the decrease in the lipid order parameter and the increase in the average helical tilt angle. Taken together, the data indicate that the structure and function of the permease are strongly dependent on the order and integrity of the lipid bilayer.
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Knowledge of the elastic properties of actin filaments is crucial for considering its role in muscle contraction, cellular motile events, and formation of cell shape. The stiffness of actin filaments in the directions of stretching and bending has been determined. In this study, we have directly determined the torsional rigidity and breaking force of single actin filaments by measuring the rotational Brownian motion and tensile strength using optical tweezers and microneedles, respectively. Rotational angular fluctuations of filaments supplied the torsional rigidity as (8.0 ± 1.2) × 10−26 Nm2. This value is similar to that deduced from the longitudinal rigidity, assuming the actin filament to be a homogeneous rod. The breaking force of the actin–actin bond was measured while twisting a filament through various angles using microneedles. The breaking force decreased greatly under twist, e.g., from 600–320 pN when filaments were turned through 90°, independent of the rotational direction. Our results indicate that an actin filament exhibits comparable flexibility in the rotational and longitudinal directions, but breaks more easily under torsional load.
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Solid-state nuclear magnetic resonance relaxation experiments were used to study the rigidity and spatial proximity of polymers in sugar beet (Beta vulgaris) cell walls. Proton T1ρ decay and cross-polarization patterns were consistent with the presence of rigid, crystalline cellulose microfibrils with a diameter of approximately 3 nm, mobile pectic galacturonans, and highly mobile arabinans. A direct-polarization, magic-angle-spinning spectrum recorded under conditions adapted to mobile polymers showed only the arabinans, which had a conformation similar to that of beet arabinans in solution. These cell walls contained very small amounts of hemicellulosic polymers such as xyloglucan, xylan, and mannan, and no arabinan or galacturonan fraction closely associated with cellulose microfibrils, as would be expected of hemicelluloses. Cellulose microfibrils in the beet cell walls were stable in the absence of any polysaccharide coating.
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A principal feature of the crystal structures of tRNAs is an L-shaped tertiary conformation in which the aminoacyl acceptor stem and the anticodon stem are approximately perpendicular. However, the anticodon-acceptor interstem angle has not been precisely quantified in solution for any tRNA. Such a determination would represent an important test of the predicted global conformation of tRNAs in solution. To this end, we have constructed a yeast tRNA(Phe) heteroduplex RNA molecule in which the anticodon and acceptor stems of the tRNA have each been extended by approximately 70 base pairs. A comparison of the rotational decay times of the heteroduplex molecule and a linear control yields an interstem angle of 89 +/- 4 degrees in 4 mM magnesium chloride/100 microM spermine hydrochloride, essentially identical to the corresponding angle observed in the crystal under similar buffer and temperature conditions. The current approach is applicable to the study of a wide variety of RNA molecules that possess elements of nonhelical structure.
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Purpose: To compare anterior and posterior corneal curvatures between eyes with primary open-angle glaucoma (POAG) and healthy eyes. Methods: This is a prospective, cross-sectional, observer-masked study. A total of 138 white subjects (one eye per patient) were consecutively recruited; 69 eyes had POAG (study group), and the other 69 comprised a group of healthy control eyes matched for age and central corneal pachymetry with the study ones. Exclusion criteria included any corneal or ocular inflammatory disease, previous ocular surgery, or treatment with carbonic anhydrase inhibitors. The same masked observer performed Goldmann applanation tonometry, ultrasound pachymetry, and Orbscan II topography in all cases. Central corneal thickness, intraocular pressure, and anterior and posterior topographic elevation maps were analyzed and compared between both groups. Results: Patients with POAG had greater forward shifting of the posterior corneal surface than that in healthy control eyes (p < 0.01). Significant differences in anterior corneal elevation between controls and POAG eyes were also found (p < 0.01). Conclusions: Primary open-angle glaucoma eyes have a higher elevation of the posterior corneal surface than that in central corneal thickness–matched nonglaucomatous eyes.
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The coherent nature of the acquisition by TerraSAR-X of both copolar channels (HH and VV) enables the generation of many different polarimetric observables with physical interpretation, as have recently been used for monitoring rice fields. In this letter, the influence of incidence angle upon these polarimetric observables is analyzed by comparing three stacks of images that were acquired simultaneously at different incidence angles (22°, 30°, and 40°) during a whole cultivation campaign. We show that the response of observables related to dominance (entropy, ratios of components) and type of scattering mechanisms (alpha angles) is not greatly influenced by incidence angle at some stages: early and advanced vegetative phases, and maturation. Moreover, the acquisition geometry drives the sensitivity to the presence of the initial stems and tillers, being detected earlier at shallower angles. This analysis is a necessary step before studying potential methodologies for combining different orbits and beams for reducing the time between acquisitions for monitoring purposes.
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Work performed at the Argonne National Laboratory.
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National Highway Traffic Safety Administration, Washington, D.C.
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National Highway Traffic Safety Administration, Washington, D.C.