1,554 research outputs found

    GROUND REACTION FORCE OF BASEBALL FLAT GROUND PITCHING

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    The purpose of this study was to describe the characteristics of the ground reaction force (GRF) of baseball flat ground pitching, and compares the characters with previous research which pitched on pitching mound. Fourteen division I college pitchers participated in this study. A VICON Motion capture system (10 cameras) and two force platforms were used to collect 3-D kinematic data (500Hz) and GRF data (1000Hz). Three successful trials for each subject were analyzed. The result shows the pivot foot anterior/posterior (AP) propulsive force was larger on flat ground, and the leading foot AP force was larger on pitching mound. The other two components GRF were similar in these two ground situations. The three components of GRF had low correlation with ball velocities. Comparing the peak GRF in three components between pitcher with fast and slow ball velocity groups, the fast velocity group produced a larger leading AP braking force. The leading foot AP breaking force may be an important variable for identify the fast and slow pitching ball velocities

    Application of zebrafish oculomotor behavior to model human disorders

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    To ensure high acuity vision, eye movements have to be controlled with astonishing precision by the oculomotor system. Many human diseases can lead to abnormal eye movements, typically of the involuntary oscillatory eye movements type called nystagmus. Such nystagmus can be congenital (infantile) or acquired later in life. Although the resulting eye movements are well characterized, there is only little information about the underlying etiology. This is in part owing to the lack of appropriate animal models. In this review article, we des­cribe how the zebrafish with its quick maturing visual system can be used to model oculomotor pathologies. We compare the characteristics and assessment of human and zebrafish eye movements. We describe the oculomotor properties of the zebrafish mutant belladonna, which has non-crossing optical fibers, and is a particularly informative model for human ocu­lomotor deficits. This mutant displays a reverse optokinetic response, spontaneous oscillations that closely mimic human congenital nystagmus and abnormal motor behavior linked to circular vectio

    Dielectrophoresis of charged colloidal suspensions

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    We present a theoretical study of dielectrophoretic (DEP) crossover spectrum of two polarizable particles under the action of a nonuniform AC electric field. For two approaching particles, the mutual polarization interaction yields a change in their respective dipole moments, and hence, in the DEP crossover spectrum. The induced polarization effects are captured by the multiple image method. Using spectral representation theory, an analytic expression for the DEP force is derived. We find that the mutual polarization effects can change the crossover frequency at which the DEP force changes sign. The results are found to be in agreement with recent experimental observation and as they go beyond the standard theory, they help to clarify the important question of the underlying polarization mechanisms

    Capture of CO2 from Coal-fired Power Plant with NaOH Solution in a Continuous Pilot-scale Bubble-column Scrubber

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    AbstractA continuous pilot-scale bubble-column scrubber with NaOH as the absorbent was used to explore the capture of CO2 gas from a coal-fired power plant. The experimental design was based on the results of previous study. The diameter of the column was 20cm and the height of the column was 2.4 m. According to the S/N ratio, parameters, including absorption rate (RA), absorption efficiency (E), overall mass-transfer coefficient (KGa) and ratio of the gas-liquid flow rate (R), were selected for Taguchi analysis to obtain optimum conditions. A total of eleven experiments were carried out to verify the optimum conditions here. The range of the gas-flow rate (Qg) and liquid-flow rate (QLT) conducted in this work were 48-192 L/min and 1.6-10 L/min, respectively. The input gas concentrations were 9-12.2%. Using a steady-state material balance with a two-film model, RA and KGa could be determined. The results showed that E, RA and KGa were in the range of 30-98%, 1.03x10-4-11.48x10-4mol/s-L and 0.018-0.058 1/s, respectively. The obtained scrubbing factors (φ) were 0.00285-0.146mol/mol-L, while R was in the range of 0.23-24.14. The dynamic behavior of the scrubber was also discussed in this study. The results could be used as a basis for commercial scale operation for the carbon capture at a power plant as well as microalgae cultivation

    From semiclassical transport to quantum Hall effect under low-field Landau quantization

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    The crossover from the semiclassical transport to quantum Hall effect is studied by examining a two-dimensional electron system in an AlGaAs/GaAs heterostructure. By probing the magneto-oscillations, it is shown that the semiclassical Shubnikov-de Haas (SdH) formulation can be valid even when the minima of the longitudinal resistivity approach zero. The extension of the applicable range of the SdH theory could be due to the damping effects resulting from disorder and temperature. Moreover, we observed plateau-plateau transition like behavior with such an extension. From our study, it is important to include the positive magnetoresistance to refine the SdH theory.Comment: 11 pages, 5 figure

    Two consecutive dural arteriovenous fistulae in a child: a case report of successful treatment with gamma knife radiosurgery

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    Introduction The occurrence of dural arteriovenous fistulae in children is quite rare. Endovascular embolization is typically the first line treatment. In general, Gamma Knife radiosurgery is used as adjuvant treatment and seldom performed as the first line treatment in children. Discussion We report a case of a 27-month-old girl who presented with an initial dural arteriovenous fistula (AVF) located at anterior base of the left middle cranial fossa. She subsequently developed another dural AVF over the left transverse-sigmoid sinus region 2 years later. Conclusion Both fistulae were successfully obliterated with Gamma Knife radiosurgery

    Neurologic phenotype of Schimke immuno-osseous dysplasia and neurodevelopmental expression of SMARCAL1

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    Schimke immuno-osseous dysplasia (OMIM 242900) is an uncommon autosomal-recessive multisystem disease caused by mutations in SMARCAL1 (swi/snf-related, matrix-associated, actin-dependent regulator of chromatin, subfamily a-like 1), a gene encoding a putative chromatin remodeling protein. Neurologic manifestations identified to date relate to enhanced atherosclerosis and cerebrovascular disease. Based on a clinical survey, we determined that half of Schimke immuno-osseous dysplasia patients have a small head circumference, and 15% have social, language, motor, or cognitive abnormalities. Postmortem examination of 2 Schimke immuno-osseous dysplasia patients showed low brain weights and subtle brain histologic abnormalities suggestive of perturbed neuron-glial migration such as heterotopia, irregular cortical thickness, incomplete gyral formation, and poor definition of cortical layers. We found that SMARCAL1 is highly expressed in the developing and adult mouse and human brain, including neural precursors and neuronal lineage cells. These observations suggest that SMARCAL1 deficiency may influence brain development and function in addition to its previously recognized effect on cerebral circulation
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