242 research outputs found
Judo in schools in South Africa:A judoka’s perspective
Elite sport systems comprise the phases of an athlete’s progression from school to international level, as incorporated in the Long-Term Athlete Development (LTAD) model. The model includes elements such as talent identification and development, scientific support, training facilities and coach development. However, varying degrees of implementation are accounted for by contextual differences. Judo is a popular Olympic sport that is practised in schools in South Africa, mostly as an extracurricular activity. The aim of this paper is to describe the perceptions of judoka in South Africa, of their school judo programmes, in the context of an elite judo system. The study utilised a self structured questionnaire and a purposive random sample of 26 judoka participated in this study. Results indicate that constrained school judo programmes exist in South Africa. The programmes would benefit from a national competition league for schools that establishes partnerships with external service and facility providers, to enhance access to scientific support such as psychology, bio-kinetics, physiotherapy, and training facilities. This would contribute to a comprehensive database, informed by monitoring and evaluation of talented athletes and would embed the programme within the framework of LTAD to establish age and developmentally appropriate participation opportunities. Unique talent identification and development approaches could also create opportunities for strategic competitive advantage. Results reinforce existing literature on long-term scientific approaches to the development of athletes and Judo South Africa’s existing LTAD manual, combined with the presence of judo in numerous schools across the country, provide a platform for practical implementation of recommendations in this study
Voorspelling van oorlewing in 'n chirurgiese intensiewesorgeenheid
Doel: Om die voorspellingswaarde van , 14 bestaande voorspellings programme op chirurgiese intensiewesorgpasiente te toets en om n oorlewingsvoorspellingsmodel vir die chirurgiese intensiewesorgeenheid (ClSE) te ontwikkel wat as instrument kan dien om kliniese besluitneming te vergemaklik. Ontwerp: Retrospektiewe en prospektiewe versameling en rekenarisering van kliniese, fisiologiese en biochemiese veranderlikes. Student se t-toets, logistiese regressie, sensitiwiteits- en spesifisiteitsberekening met behulp van tweerigting tabelle. Plek: Chirurgiese Intensiewesorgeenheid, H. F. Verwoerd-hospitaal, Pretoria. Pasientpopulasie: Retrospektiewe deel van studie: 188 pasiente; prospektiewe deel: 104 pasiente. Bevindingsmaatstawwe: Statisties betekenisvolle verskille tussen die tellings van oorlewendes en nieoorlewendes. Aanvaarbare sensitiwiteit en spesifisiteit van ontwikkelde model. Resultate: AI 14 bestaande voorspellingsprogramme beskik oor die vennoe om te onderskei tussen die opnamedagtellings van oorlewendes en nie-oorlewendes en het, by implikasie, dus prognostiese geldigheid. Die statistiese betekenisvolheid geassosieer met die onderskeie programme het gewissel van P < 0.01 tot P < 0.0001. 'n Reeks van opeenvolgende oorlewingsvoorspel1ingsmodelle, ontwikkel deur logistiese regressie-analise op die bes passende voorspellingsprogramme, het uiteindelik gelei tot die ontwikkeling van 'n model met 'n sensitiwiteit van 93% en 'n spesifisiteit van 66%. Gevolgtrekking: Verskeie bestaande voorspellingsprogramme kan bydra tot kliniese besluitneming. Voorspellingsmodelle hieruit ontwikkel moet voor implementering herhaaldelik op opeenvolgende groepe van die teikenpopulasie getoets word. Beide die programme en die modelle behoort as bykomstige prognostiese ondersteuningsfaktore gebruik te word eerder as absolute aanduidings van uitkoms.S Afr Med J 1996: 86: 1417 -142
Using Topological Statistics to Detect Determinism in Time Series
Statistical differentiability of the measure along the reconstructed
trajectory is a good candidate to quantify determinism in time series. The
procedure is based upon a formula that explicitly shows the sensitivity of the
measure to stochasticity. Numerical results for partially surrogated time
series and series derived from several stochastic models, illustrate the
usefulness of the method proposed here. The method is shown to work also for
high--dimensional systems and experimental time seriesComment: 23 RevTeX pages, 14 eps figures. To appear in Physical Review
Test 1157: John Deere 2630 and 2640 Diesel
EXPLANATION OF TEST REPORT GENERAL CONDITIONS East tractor is a production model equipped for common usage. Power consuming accessories can be disconnected only when it is convenient for the operator to do so in practice. Additional weight can be added as ballast if the manufacturer regularly supplies it for sale. The static tire loads and the inflation pressures muse conform to recommendations in the Tire Standards published by the Society of Automotive Engineers. PREPARATION FOR PERFORMANCE RUNS The engine crank case is drained and refilled with a measured amount of new oil conforming to specifications in the operator’s manual. The fuel used and the maintenance operations must also conform to the published information delivered with the tractor. The tractor is then limbered-up for 1 hour on drawbar work in accordance with the manufacturers published recommendations. The manufacturer’s representative is present to make appropriate decisions regarding mechanical adjustments. The tractor is equipped with approximately the amount of added ballast that is used during maximum drawbar tests. The tire tread-bar height must be at least 65% of new tread height prior to the maximum power run. BELT OR POWER TAKE-OFF PERFORMANCE Maximum Power and Fuel Consumption. The manufacturer’s representative makes carburetor, fuel pump, ignition and governor control settings which remain unchanged throughout tall subsequent runs. The governor and the manually operated governor control lever is set to provide the high-idle speed specified by the manufacturer for maximum power. Maximum power is measured by connecting the belt pulley or the power take-off to a dynamometer. The dynamometer load is then gradually increased until the engine is operating at the rated speed specified by the manufacturer for maximum power. The corresponding fuel consumption is measured. Varying Power and Fuel Consumption. Six different horsepower levels are used to show corresponding fuel consumption rates and how the governor causes the engine to react to the following changes in dynamometer load: 85% of the dynamometer torque at maximum power; minimum dynamometer torque, ½ the 85% torque; maximum power; ¼ and ¾ of the 85% torque. Since at tractor is generally subjected to varying loads the average of the results in this test serve well for predicting the fuel consumption of a tractor in general usage. DRAWBAR PERFORMANCE All engine adjustments are the same as those used in the belt or power take-off tests. If the manufacturer specifies a different rated crankshaft speed for drawbar operations, then the position of the manually operated governor control is changed to provide the high-idle speed specified by the manufacturer in the operating instructions. Varying Power and Fuel Consumption With Ballast. The varying power runs are made to show the effect of speed-control devices (engine governor, automatic transmissions, etc.) on horsepower, speed and fuel consumption. These runs are made around the entire test course with has two 180 degree turns with a minimum radius of 50 feet. The drawbar pull is set at 3 different levels as follows: (1) as near to the pull a maximum power as possible and still have the tractor maintain the travel speed at maximum horsepower on the straight sections of the test course; (2) 75% of the pull at maximum power; and (3) 50% of the pull at maximum power. Prior to 1958, fuel consumption data (10 hour test) were shown only for the pull obtained at maximum power for tractors having torque converters and at 75% of the pull obtained at maximum power for gear-type tractors. Maximum Power With Ballast. Maximum power is measured on straight level sections of the test course. Data are shown for not more that 12 different gears or travel speeds. Some gears or travel speeds may be omitted because of high slippage of the traction members or because the travel speed may exceed the safe-limit for the test course. The maximum safe speed for the Nebraska Test course has been set at 15 miles per hour. The slippage limits have been set at 15% and 7% for pneumatic tires and steel tracks or lugs, respectively. Higher slippage gives widely varying results. Maximum Power Without Ballast. All added ballast is removed from the tractor. The maximum drawbar power of the tractor is determined by the same procedure used for getting maximum power with ballast. The gear (or travel speed) is the same as that used in the 10-hours test. Varying Power and Travel Speed With Ballast. Travel speeds corresponding to drawbar pulls beyond the maximum power range are obtained to show the “lugging ability” of the tractor. The run starts with the pull at maximum power; then additional drawbar pull is applied to cause decreasing speeds. The run is ended by one of three conditions; (1) maximum pull is obtained, (2) the maximum slippage limit is reached, or (3) some other operating limit is reached
The ANTARES Optical Beacon System
ANTARES is a neutrino telescope being deployed in the Mediterranean Sea. It
consists of a three dimensional array of photomultiplier tubes that can detect
the Cherenkov light induced by charged particles produced in the interactions
of neutrinos with the surrounding medium. High angular resolution can be
achieved, in particular when a muon is produced, provided that the Cherenkov
photons are detected with sufficient timing precision. Considerations of the
intrinsic time uncertainties stemming from the transit time spread in the
photomultiplier tubes and the mechanism of transmission of light in sea water
lead to the conclusion that a relative time accuracy of the order of 0.5 ns is
desirable. Accordingly, different time calibration systems have been developed
for the ANTARES telescope. In this article, a system based on Optical Beacons,
a set of external and well-controlled pulsed light sources located throughout
the detector, is described. This calibration system takes into account the
optical properties of sea water, which is used as the detection volume of the
ANTARES telescope. The design, tests, construction and first results of the two
types of beacons, LED and laser-based, are presented.Comment: 21 pages, 18 figures, submitted to Nucl. Instr. and Meth. Phys. Res.
A First Search for coincident Gravitational Waves and High Energy Neutrinos using LIGO, Virgo and ANTARES data from 2007
We present the results of the first search for gravitational wave bursts
associated with high energy neutrinos. Together, these messengers could reveal
new, hidden sources that are not observed by conventional photon astronomy,
particularly at high energy. Our search uses neutrinos detected by the
underwater neutrino telescope ANTARES in its 5 line configuration during the
period January - September 2007, which coincided with the fifth and first
science runs of LIGO and Virgo, respectively. The LIGO-Virgo data were analysed
for candidate gravitational-wave signals coincident in time and direction with
the neutrino events. No significant coincident events were observed. We place
limits on the density of joint high energy neutrino - gravitational wave
emission events in the local universe, and compare them with densities of
merger and core-collapse events.Comment: 19 pages, 8 figures, science summary page at
http://www.ligo.org/science/Publication-S5LV_ANTARES/index.php. Public access
area to figures, tables at
https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=p120000
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Wavelet-based ULF wave diagnosis of substorm expansion phase onset
Using a discrete wavelet transform with a Meyer wavelet basis, we present a new quantitative algorithm for determining the onset time of Pi1 and Pi2 ULF waves in the nightside ionosphere with ∼20- to 40-s resolution at substorm expansion phase onset. We validate the algorithm by comparing both the ULF wave onset time and location to the optical onset determined by the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE)–Far Ultraviolet Imager (FUV) instrument. In each of the six events analyzed, five substorm onsets and one pseudobreakup, the ULF onset is observed prior to the global optical onset observed by IMAGE at a station closely conjugate to the optical onset. The observed ULF onset times expand both latitudinally and longitudinally away from an epicenter of ULF wave power in the ionosphere. We further discuss the utility of the algorithm for diagnosing pseudobreakups and the relationship of the ULF onset epicenter to the meridians of elements of the substorm current wedge. The importance of the technique for establishing the causal sequence of events at substorm onset, especially in support of the multisatellite Time History of Events and Macroscale Interactions During Substorms (THEMIS) mission, is also described
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