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Maximum Speed (maximum + speed)
Selected AbstractsFast Reciprocating Probe Assembly for the KSTARCONTRIBUTIONS TO PLASMA PHYSICS, Issue 5-6 2006J. G. Bak Abstract A fast reciprocating probe assembly (FRPA) that can scan a distance of up to 32.5 cm with a maximum speed of 1.7 m/s was fabricated to obtain the spatial profile of basic plasma parameters in the edge region of the KSTAR plasma during a plasma discharge of 20 s. The probe driving mechanism consists of two parts; first a slow movement driven by a servo motor system and then a fast reciprocating movement actuated by a pneumatic system. A performance test of the drive system, which is remotely controlled by a PC, was carried out. The prototype of the probe head for the KSTAR FRPA was fabricated as a modular type for easy replacement. It was installed in the fast injection probe assembly (FIPA) in the Hanbit magnetic mirror device, and a radial plasma parameter profile measurement was carried out. The performance test results of the drive system and the profile measurements using the probe head are presented. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The effect of training on stride parameters in a cohort of National Hunt racing Thoroughbreds: A preliminary studyEQUINE VETERINARY JOURNAL, Issue 5 2009M. FERRARI Summary Reasons for performing study: The influence of training on stride parameters is controversial and to date there is no information on how training influences stride parameters during high-speed locomotion in the field. Objective: To determine the influence of training on stride variables during high-speed locomotion in Thoroughbred racehorses. Methods: Speed, stride frequency, stance and protraction times were quantified in 8 Thoroughbreds with foot mounted accelerometers and GPS sensors during their first week of canter after the summer break and 6 months into training. Results: At a speed of 11 m/s, stride frequency was (mean ± s.d.) 2.160 ± 0.120 strides/s pre- and 2.167 ± 0.083 strides/s post training; mean stance time was 125.3 ± 9 ms pre- and 125.9 ± 7 ms post training; protraction time was 340.7 ± 20.4 ms pre- and 337.2 ± 14.3 ms post training. The increase in stride frequency and the decrease in protraction time after training were significant. There was no statistically significant difference in the maximum speed reached by each horse pre- and post training. Conclusions: Stance time stayed constant throughout the training season in the tested horses. A significant decrease in protraction time and a corresponding significant increase in stride frequency were observed after training. Potential relevance: Training of racehorses could be adapted to maximise the effect on modifiable parameters and reduce the risk of training-induced pathologies. Further research will be conducted to investigate the effect of different training protocols on a large number of horses. [source] Is improved high speed performance following frusemide administration due to diuresis-induced weight loss or reduced severity of exercise-induced pulmonary haemorrhage?EQUINE VETERINARY JOURNAL, Issue S36 2006X. A. ZAWADZKAS Summary Reasons for performing study: Prerace administration of frusemide to horses has been linked with a significant improvement in racing performance, but the basis for this improvement is unclear. Objective: To test whether improved performance with prerace administration of frusemide is due to the drug's diuresis-induced weight loss rather than its apparent alleviation of exercise-induced pulmonary haemorrhage (EIPH). Methods: Eight thoroughbred horses underwent 3 trials in a random order, 2 or 3 weeks apart: control (C), frusemide/unburdened (FU), and frusemide/burdened (FB). None of the horses were known to have exhibited post-exercise epistaxis or endoscopic evidence of EIPH. Endoscope-guided bronchoalveolar lavages (BALs) were performed before and after each horse completed a standardised exercise test (SET) on an inclined treadmill to assess semi-quantitatively the volume of EIPH. For C, horses received an i.v. saline placebo injection (5 ml) and were unburdened while performing the SET. With FU, horses received frusemide (0.5 mg/kg) and were also unburdened. For FB, horses received frusemide and were burdened with weight equal to that lost during the 4 h post frusemide injection period. Erythrocyte number in BAL fluid, mass specific VO2max, time and distance for the entire SET as well as at maximum speed were recorded. A one-way repeated measures analysis of variance was conducted on all results. Results: Mass specific VO2max was significantly higher for the FU than for FB or C. Mass specific VO2max for FB and C were not different. More RBCs were found in BAL samples after C runs than after both FU and FB trial runs. Horses with the frusemide treatment (either burdened or unburdened) produced less EIPH than in the C trial, but their mass specific VO2max values were higher on the FU trial alone. For FU, horses ran longer at 115% VO2max than under C or FB conditions. Conclusion and potential relevance: Improvement of performance in the furosemide trials was due more to the weight-loss related effects of the drug than its apparent alleviation of EIPH. Further research is warranted with the same or similar project design, but with a larger sample size and with horses known to have more severe EIPH. [source] Magnetic Control of Tubular Catalytic Microbots for the Transport, Assembly, and Delivery of Micro-objectsADVANCED FUNCTIONAL MATERIALS, Issue 15 2010Alexander A. Solovev Abstract Recently a significant amount of attention has been paid towards the development of man-made synthetic catalytic micro- and nanomotors that can mimic biological counterparts in terms of propulsion power, motion control, and speed. However, only a few applications of such self-propelled vehicles have been described. Here the magnetic control of self-propelled catalytic Ti/Fe/Pt rolled-up microtubes (microbots) that can be used to perform various tasks such as the selective loading, transportation, and delivery of microscale objects in a fluid is shown; for instance, it is demonstrated for polystyrene particles and thin metallic films ("nanoplates"). Microbots self-propel by ejecting microbubbles via a platinum catalytic decomposition of hydrogen peroxide into oxygen and water. The fuel and surfactant concentrations are optimized obtaining a maximum speed of 275,µm,s,1 (5.5 body lengths per second) at 15% of peroxide fuel. The microbots exert a force of around 3.77,pN when transporting a single 5,µm diameter particle; evidencing a high propulsion power that allows for the transport of up to 60 microparticles. By the introduction of an Fe thin film into the rolled-up microtubes, their motion can be fully controlled by an external magnetic field. [source] Numerical simulation of a dam break for an actual river terrain environmentHYDROLOGICAL PROCESSES, Issue 4 2007C. B. Liao Abstract A two-dimensional (2D) finite-difference shallow water model based on a second-order hybrid type of total variation diminishing (TVD) approximate solver with a MUSCL limiter function was developed to model flooding and inundation problems where the evolution of the drying and wetting interface is numerically challenging. Both a minimum positive depth (MPD) scheme and a non-MPD scheme were employed to handle the advancement of drying and wetting fronts. We used several model problems to verify the model, including a dam break in a slope channel, a dam break flooding over a triangular obstacle, an idealized circular dam-break, and a tide flow over a mound. Computed results agreed well with the experiment data and other numerical results available. The model was then applied to simulate the dam breaking and flooding of Hsindien Creek, Taiwan, with the detailed river basin topography. Computed flooding scenarios show reasonable flow characteristics. Though the average speed of flooding is 6,7 m s,1, which corresponds to the subcritical flow condition (Fr < 1), the local maximum speed of flooding is 14·12 m s,1, which corresponds to the supercritical flow condition (Fr , 1·31). It is necessary to conduct some kind of comparison of the numerical results with measurements/experiments in further studies. Nevertheless, the model exhibits its capability to capture the essential features of dam-break flows with drying and wetting fronts. It also exhibits the potential to provide the basis for computationally efficient flood routing and warning information. Copyright © 2006 John Wiley & Sons, Ltd. [source] Heterogeneous traffic flow modelling for an arterial using grid based approachJOURNAL OF ADVANCED TRANSPORTATION, Issue 4 2008P. J. Gundaliya Abstract A grid based modelling approach akin to cellular automata (CA) is adopted for heterogeneous traffic flow simulation. The road space is divided into a grid of equally sized cells. Moreover, each vehicle type occupies one or more cell as per its size unlike CA traffic flow model where each vehicle is represented by a single cell. Model needs inputs such as vehicle size, its maximum speed, acceleration, deceleration, probability constants, and arrival pattern. The position and speed of the vehicles are assumed to be discrete. The speed of each vehicle changes according to its interactions with other vehicles, following some stochastic rules depending on the circumstances. The model is calibrated and validated using real data and VISSIM. The results indicate that grid based model can reasonably well simulate complex heterogeneous traffic as well as offers higher computational efficiency needed for real time application. [source] Automatic regulation of occlusal force because of hardness-change of the bite objectJOURNAL OF ORAL REHABILITATION, Issue 1 2008A. SHIMADA Summary, It is considered that the information of chewed food, such as size and texture, is important for smooth mastication. In this study, we analysed aspects of the control of occlusal force, by experimentally reproducing situations in which the hardness of food changed unpredictably during mastication, using a device that utilized a 3-sectioned urethane rubber piece with different hardness values. Seven healthy subjects were instructed to perform repetitive jaw open,close movements paced by a metronome (1·0 Hz) and to maintain constant occlusal force throughout the trial. Using the device, the following parameters were measured during the first to fifth strokes after changing the hardness, peak value, impulse, duration and time to peak of occlusal force in the waveform of occlusal force, cycle time of open,close jaw movements, jaw gape and maximum speed in the closing phase in the waveform of the jaw movements. Each parameter value was statistically analysed by anova with Fisher's least significant difference method (P < 0·05). Peak occlusal force, impulse and jaw gape were significantly affected by the change in hardness, while an increase in hardness caused increases in the values for peak occlusal force and impulse against the instruction, after which those values remained constant while the subjects occluded the same level of hardness. Our results indicate that the level of the resulting occlusal force is regulated automatically according to the hardness of the chewed food. We concluded that occlusal force was adapted for efficient mastication when the hardness of foods changes unpredictably. [source] Different effects of cardiac versus skeletal muscle regulatory proteins on in vitro measures of actin filament speed and forceTHE JOURNAL OF PHYSIOLOGY, Issue 3 2005Emilie Warner Clemmens Mammalian cardiac and skeletal muscle express unique isoforms of the thin filament regulatory proteins, troponin (Tn) and tropomyosin (Tm), and the significance of these different isoforms in thin filament regulation has not been clearly identified. Both in vitro and skinned cellular studies investigating the mechanism of thin filament regulation in striated muscle have often used heterogeneous mixtures of Tn, Tm and myosin isoforms, and variability in reported results might be explained by different combinations of these proteins. Here we used in vitro motility and force (microneedle) assays to investigate the influence of cardiac versus skeletal Tn and Tm isoforms on actin,heavy meromyosin (HMM) mechanics. When interacting with skeletal HMM, thin filaments reconstituted with cardiac Tn/Tm or skeletal Tn/Tm exhibited similar speed,calcium relationships and significantly increased maximum speed and force per filament length (F/l) at pCa 5 (versus unregulated actin filaments). However, augmentation of F/l was greater with skeletal regulatory proteins. Reconstitution of thin filaments with the heterogeneous combination of skeletal Tn and cardiac Tm decreased sliding speeds at all [Ca2+] relative to thin filaments with skeletal Tn/Tm. Finally, for filaments reconstituted with any heterogeneous mix of Tn and Tm isoforms, force was not potentiated over that of unregulated actin filaments. Combined the results suggest (1) that cardiac regulatory proteins limit the allosteric enhancement of force, and (2) that Tn and Tm isoform homogeneity is important when studying Ca2+ regulation of crossbridge binding and kinetics as well as mechanistic differences between cardiac and skeletal muscle. [source] Transplanted glioma cells migrate and proliferate on host brain vasculature: A dynamic analysisGLIA, Issue 8 2006Azadeh Farin Abstract Glioma cells have a remarkable capacity to infiltrate the brain and migrate long distances from the tumor, making complete surgical resection impossible. Yet, little is known about how glioma cells interact with the complex microenvironment of the brain. To investigate the patterns and dynamics of glioma cell infiltration and migration, we stereotactically injected eGFP and DsRed-2 labeled rat C6 glioma cells into neonatal rat forebrains and used time-lapse microscopy to observe glioma cell migration and proliferation in slice cultures generated from these brains. In this model, glioma cells extensively infiltrated the brain by migrating along the abluminal surface of blood vessels. Glioma cells intercalated their processes between the endothelial cells and the perivascular astrocyte end feet, but did not invade into the blood vessel lumen. Dynamic analysis revealed notable similarities between the migratory behavior of glioma cells and that previously observed for glial progenitor cells. Glioma cells had a characteristic leading process and migrated in a saltatory fashion, with bursts of migration separated by periods of immobility, and maximum speeds of over 100 ,m/h. Migrating glioma cells proliferated en route, pausing for as short as an hour to divide before the daughter cells resumed migrating. Remarkably, the majority of glioma cell divisions took place at or near vascular branch points, suggesting that mitosis is triggered by local environmental cues. This study provides the first dynamic analysis of glioma cell infiltration in living brain tissue and reveals that the migration and proliferation of transplanted glioma cells is directed by interactions with host brain vasculature. © 2006 Wiley-Liss, Inc. [source] | ||||||||||||||||