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Efficiency of thin film photocells  [PDF]
D. Mozyrsky,I. Martin
Physics , 2007, DOI: 10.1016/j.optcom.2007.04.062
Abstract: We propose a new concept for the design of high-efficiency photocells based on ultra-thin (submicron) semiconductor films of controlled thickness. Using a microscopic model of a thin dielectric layer interacting with incident electromagnetic radiation we evaluate the efficiency of conversion of solar radiation into the electric power. We determine the optimal range of parameters which maximize the efficiency of such photovoltaic element.
Analysis of the linear sprint speed of soccer players using two assessment methods
Bruno Natale Pasquarelli,Luiz Cláudio Reeberg Stanganelli,Antonio Carlos Dourado,Mathias Roberto Loch
Revista Brasileira de Cineantropometria e Desempenho Humano , 2009,
Abstract: The aim of this study was to analyze the performance of soccer players in a 40-m sprint test using two different assessment methods. A total of 154 professional soccer players from the 1st Division of Paraná State were studied between 2002 and 2006. Sprint speed was measured with a set of photocells positioned on the start line (0 m) and at 10, 20, 30 and 40 m. The athletes were divided into three subgroups according to performance (final time) in the 40-m sprint test and were classified as fast (4.877-5.17 s), intermediate fast (5.175-5.474 s), and slow (5.475-5.766 s). The same 154 athletes were divided according to their field positions into center back, back side, defensive midfielder, offensive midfielder, and forward. In both methods, ANOVA (one-way) was used for the comparison of average time between subgroups at the different distances. For the method classifying athletes according to performance, the Tukey post-hoc test showed a significant difference between all subgroups. Differences, although not significant, were observed between subgroups classified according to field position during the match. In conclusion, the two methods for the analysis of linear sprint speed in soccer players permit the identification of relevant aspects that could be applied to the prescription of training velocity for each subgroup according to their field position during the match.
FAMILIARISATION AND RELIABILITY OF SPRINT TEST INDICES DURING LABORATORY AND FIELD ASSESSMENT  [cached]
James G. Hopker,Damian A. Coleman,Jonathan D. Wiles,Andrew Galbraith
Journal of Sports Science and Medicine , 2009,
Abstract: The aim of the study was to assess the reliability of sprint performance in both field and laboratory conditions. Twenty-one male (mean ± s: 19 ± 1 years, 1.79 ± 0.07 m, 77.6 ± 7.1 kg) and seventeen female team sport players (mean ± s: 21 ± 4 years, 1.68 ± 0. 07 m, 62.7 ± 4.7 kg) performed a maximal 20-metre sprint running test on eight separate occasions. Four trials were conducted on a non-motorised treadmill in the laboratory; the other four were conducted outdoors on a hard-court training surface with time recorded by single-beam photocells. Trials were conducted in random order with no familiarisation prior to testing. There was a significant difference between times recorded during outdoor field trials (OFT) and indoor laboratory trials (ILT) using a non-motorised treadmill (3.47 ± 0.53 vs. 6.06 ±1.17s; p < 0.001). The coefficient of variation (CV) for time was 2.55-4.22% for OFT and 5.1-7.2% for ILT. During ILT peak force (420.9 ± 87.7N), mean force (147.2 ± 24.7N), peak power (1376.8 ± 451.9W) and mean power (514.8 ± 164.4W), and were measured. The CV for all ILT variables was highest during trial 1-2 comparison. The CV (95% confidence interval) for the trial 3-4 comparison yielded: 9.4% (7.7-12. 1%), 7.9% (6.4-10.2%), 10.1% (8.2-13.1%) and 6.2% (5.1-8.0%) for PF, MF, PP and MP and respectively. The results indicate that reliable data can be derived for single maximal sprint measures, using fixed distance protocols. However, significant differences in time/speed over 20-m exist between field and laboratory conditions. This is primarily due to the frictional resistance in the non- motorised treadmill. Measures of force and power during ILT require at least 3 familiarisations to reduce variability in test scores
Organ failure and tight glycemic control in the SPRINT study
J Geoffrey Chase, Christopher G Pretty, Leesa Pfeifer, Geoffrey M Shaw, Jean-Charles Preiser, Aaron J Le Compte, Jessica Lin, Darren Hewett, Katherine T Moorhead, Thomas Desaive
Critical Care , 2010, DOI: 10.1186/cc9224
Abstract: A retrospective analysis of 371 patients (3,356 days) on SPRINT (August 2005 - April 2007) and 413 retrospective patients (3,211 days) from two years prior, matched by Acute Physiology and Chronic Health Evaluation (APACHE) III. SOFA is calculated daily for each patient. The effect of the SPRINT TGC intervention is assessed by comparing the percentage of patients with SOFA ≤5 each day and its trends over time and cohort/group. Organ-failure free days (all SOFA components ≤2) and number of organ failures (SOFA components >2) are also compared. Cumulative time in 4.0 to 7.0 mmol/L band (cTIB) was evaluated daily to link tightness and consistency of TGC (cTIB ≥0.5) to SOFA ≤5 using conditional and joint probabilities.Admission and maximum SOFA scores were similar (P = 0.20; P = 0.76), with similar time to maximum (median: one day; IQR: [1,3] days; P = 0.99). Median length of stay was similar (4.1 days SPRINT and 3.8 days Pre-SPRINT; P = 0.94). The percentage of patients with SOFA ≤5 is different over the first 14 days (P = 0.016), rising to approximately 75% for Pre-SPRINT and approximately 85% for SPRINT, with clear separation after two days. Organ-failure-free days were different (SPRINT = 41.6%; Pre-SPRINT = 36.5%; P < 0.0001) as were the percent of total possible organ failures (SPRINT = 16.0%; Pre-SPRINT = 19.0%; P < 0.0001). By Day 3 over 90% of SPRINT patients had cTIB ≥0.5 (37% Pre-SPRINT) reaching 100% by Day 7 (50% Pre-SPRINT). Conditional and joint probabilities indicate tighter, more consistent TGC under SPRINT (cTIB ≥0.5) increased the likelihood SOFA ≤5.SPRINT TGC resolved organ failure faster, and for more patients, from similar admission and maximum SOFA scores, than conventional control. These reductions mirror the reduced mortality with SPRINT. The cTIB ≥0.5 metric provides a first benchmark linking TGC quality to organ failure. These results support other physiological and clinical results indicating the role tight, consistent TGC can play in reducin
Attentional and visual demands for sprint performance in non-fatigued and fatigued conditions: reliability of a repeated sprint test
Inge HF Reininga, Koen APM Lemmink, Ron L Diercks, Arina T Buizer, Martin Stevens
BMC Musculoskeletal Disorders , 2010, DOI: 10.1186/1471-2474-11-84
Abstract: Twenty-seven healthy athletes were included in the study. To determine test-retest reliability, a subgroup of 19 athletes performed the figure-of-eight sprint test twice. The figure-of-eight sprint test consisted of nine 30-second sprints. The sprint test consisted of three test parts: sprinting without any restriction, with an attention-demanding task, and with restricted vision. Increases in sprint times with the attention-demanding task or restricted vision are reflective of the attentional and visual demands for sprinting. Intraclass correlation coefficients (ICCs) and mean difference between test and retest with 95% confidence limits (CL) were used to assess test-retest reliability. Repeated-measures ANOVA were used for comparisons between the sprint times and fatigue measurements of the test parts in both a non-fatigued and fatigued condition.The figure-of-eight sprint test showed good test-retest reliability, with ICCs ranging from 0.75 to 0.94 (95% CL: 0.40-0.98). Zero lay within the 95% CL of the mean differences, indicating that no bias existed between sprint performance at test and retest. Sprint times during the test parts with attention-demanding task (P = 0.01) and restricted vision (P < 0.001) increased significantly compared to the base measurement. Furthermore the sprint times and fatigue measurements increased significantly in fatigued condition. There was a significant interaction effect between test part and level of fatigue (P = 0.03).High ICCs and the absence of systematic variation indicate good test-retest reliability of the figure-of-eight sprint test. The attentional and visual demands for sprint performance, in both a non-fatigued and fatigued condition, can be measured in healthy team-sport athletes with the figure-of-eight sprint test.Physical performance measures are widely used to assess physical function for sports or rehabilitation purposes. Although such measures for e.g. sprint performance, jump strength and hop performance may del
A COMPARISON OF PUBLISHED HAZ THERMAL SIMULATION METHODS USED TO DERIVEE WELD HAZ THERMAL CYCLES
C D Lundin,and C Zhou,
C. D. Lundin
,and C. Zhou

金属学报(英文版) , 2000,
Abstract: Accurate thermal simulation is the key in the simulation approach to defining the unique microstructure and properties of the HAZ regions. Simulation enables an expansion of the volume of material char- acteristic of each H4Z region to a sufficient size for property determination.The combined influence of heat input,preheat temperature, plate thickness, and widing process on HAZ microstructure and properties relics on the accurate simulation of thermal cycles corresponding to different peak temperatures using an HAZ simulator like the Gleeble.Several computer programs have been developed to predict thermal excursions in various HAZ regions during welding. Some were developed based simply on the thermal propertics of a material;whereas, others were generated on the basis of actual experimental data.A suitable HAZ thermal simulation program must be ons that can authntically duplicate an ac- tual thermal cycle experienced during welding within reasonable limies. Therefore, the similarities and differences among the HAZ thermal cycles predicted by various methodologies should be fully under- stood. A total of sts thermal cycle prediction methodologies were compared in this evaluation. It was de- termined that some HAZ simulation programs have sever limitations due to the idealized assumptions considered in their development.According to the experieare at The University of Tennessee and the comparison results in this study, the HAZ thermal simulation programs; " HAZ Calculator" and F(s, d); are recommended for accurate HAZ thermal cycle duplication.
Muscle power and repeated sprint ability in soccer players
Juliano Dal Pupo,Carlos Miguel Porto Almeida,Daniele Detanico,Juliano Fernandes da Silva
Revista Brasileira de Cineantropometria e Desempenho Humano , 2010,
Abstract: Muscle power is one of the most important physical qualities of soccer playerperformance and needs to be maintained during a match. Thus, the aim of this study was toinvestigate the levels of muscle power in soccer players before and after performing repeatedsprints (RS), and the association between power and RS performance. Twenty soccer playersfrom the under-20 category aged 18-20 years participated in this study. The study consisted ofthe execution of vertical jumps, execution of RS, new execution of vertical jumps, and collectionof blood samples. The continuous jump (CJ) test was performed on a piezoelectric force platformfor the measurement of muscle power and the RAST test was used to evaluate RS ability. Nosignificant difference in the levels of muscle power was observed after RS (p=0.57). Significantdifferences were observed in the first to fifth sprint times (p<0.01), but not between the fifth andsixth sprint (p=0.06). CJ height before RS was correlated with first sprint time (r=-0.62, p<0.01),best sprint time (r=-0.60, p<0.01), and average sprint time (r= -0.54, p<0.01). In conclusion,the soccer players studied showed no significant reduction in muscle power after RS. A decreasein performance was observed from the first to the fifth sprint, but not between the fifth and sixthsprint. The muscle power of soccer players was a determinant factor to perform one maximumsprint, as well as successive sprints.
Phylogenetic and Ontogenetic determinants of sprint performance in some diurnal Kalahari Lizards
R. B Huey
Koedoe : African Protected Area Conservation and Science , 1982, DOI: 10.4102/koedoe.v25i1.602
Abstract: Sprint capacities (maximum speed, acceleration, stride length, stride frequency) of diurnal lizards from the Kalahari were measured on sandy substrates in the laboratory. Despite major interfamilial differences in body sizes and in body proportions, measures of sprint capacity were remarkably similar among families: some heavy bodied skinks ran as fast as did some sleek lacertids. Sprint capacities change during ontogeny in lizards. Maximum speed, stride length, and possibly acceleration all increase with size and presumably with age.
SPRINT: A new parallel framework for R
Jon Hill, Matthew Hambley, Thorsten Forster, Muriel Mewissen, Terence M Sloan, Florian Scharinger, Arthur Trew, Peter Ghazal
BMC Bioinformatics , 2008, DOI: 10.1186/1471-2105-9-558
Abstract: We have designed and built a prototype framework that allows the addition of parallelised functions to R to enable the easy exploitation of HPC systems. The Simple Parallel R INTerface (SPRINT) is a wrapper around such parallelised functions. Their use requires very little modification to existing sequential R scripts and no expertise in parallel computing. As an example we created a function that carries out the computation of a pairwise calculated correlation matrix. This performs well with SPRINT. When executed using SPRINT on an HPC resource of eight processors this computation reduces by more than three times the time R takes to complete it on one processor.SPRINT allows the biostatistician to concentrate on the research problems rather than the computation, while still allowing exploitation of HPC systems. It is easy to use and with further development will become more useful as more functions are added to the framework.The last few years have seen the widespread introduction of high-throughput and highly parallel post genomic experiments to biological research, leading to hardware bottlenecks in the analysis of such high-dimensional data. Microarray-based techniques are a prominent example, allowing for simultaneous measurement of thousands to millions of genes or sequences across tens to thousands of different samples [1]. These measurements can represent the expression of all genes in the human genome across thousands of cancer tissue samples, or the individual gene sequence differences between thousands of patients [2,3]. These studies have generated an unprecedented amount of data and tested the limits of existing bioinformatics computing infrastructure, for example, whole genome analysis becomes intractable for any experiment with more than a few hundred arrays, depending on hardware available. Emerging whole genome associative studies and clinical projects will require from several hundreds to several thousands of microarray experiments. The complexity
Dynamic factors and electromyographic activity in a sprint start
M ?oh,S Peharec,P Ba?i?,T Kampmiller
Biology of Sport , 2009,
Abstract: The aim of the study was to establish the major dynamic parameters as well as the EMG activation of muscles in a sprint start as the first derivative of sprint velocity. The subject of the analysis was block velocity, the production of force in the front and rear starting blocks, the block acceleration in the first two steps and the electromyographic activity (EMG) of the following muscles: the erector spinae muscle, gluteus maximus muscle, rectus femoris muscle, vastus medialis muscle, vastus lateralis muscle, biceps femoris muscle and gastrocnemius–medialis muscle. One international-class female sprinter participated in the experiment. She performed eight starts in constant laboratory conditions. The 3-D kinematic analysis was made using a system of nine Smart-e 600 cameras operating at a frame rate of 60 Hz. Dynamic parameters were established by means of two separate force platforms to which the starting blocks were fixed. A 16-channel electromyograph was used to analyse electromyographic activity (EMG). It was established that the block velocity depended on the absolute force produced in the front and rear starting blocks and that it was 2.84±0.21 m.s-1. The maximal force on the rear and front blocks was 628±34 N and 1023±30 N, respectively. In view of the total impulse (210±11 Ns) the force production/time ratio in the rear and front blocks was 34%:66%. The erector spinae muscle, vastus lateralis muscle and gastrocnemius–medialis muscle generate the efficiency of the start. The block acceleration in the first two steps primarily depends on the activation of the gluteus maximus muscle, rectus femoris muscle, biceps femoris muscle and gastrocnemius–medialis muscle. A sprint start is a complex motor stereotype requiring a high degree of integration of the processes of central movement regulation and an optimal level of biomotor abilities.
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