COMPARISON OF MALE AND FEMALE PEAK TORQUE USING A VARIABLE NUMBER OF REPETITIONS DURING A KNEE JOINT ISOKINETIC TEST

The purpose of this study was to assess peak torque in males and females using a variable number of repetitions at five different isokinetic velocities. Sixty subjects, males and females, athletes and non athletes were tested on four separate occasions. Each testing session the subject executed a set number of repetitions, either 4, 6, 8, or 10, at velocities of 60, 120, 180, 240 and 300 o·s-1 with a 60 second rest period between each velocity set. The order of repetitions was randomly assigned. A 2 X 2 X 4 X 5 repeated measures ANOVA was used to analyze the data with &#945; < .05. The independent variables were gender, athlete, repetitions, and velocity with peak torque as the dependent variable. The following were found to be significant: interaction between gender and velocity; athlete and velocity; velocity; gender; athlete/non athlete; but no significant differences in number of repetitions were found. Therefore, peak torque was demonstrated equally regardless of the number of repetitions. However, by carefully reviewing the data for females it was evident that the women athletes did not reach peak torque at any of the five velocities when they executed four repetitions. In the female non athletes only at the higher velocities did they reach peak torque with four repetitions. It was concluded that females may need more repetitions to achieve peak torque than their male counterparts and that this should be taken into account when they are being tested for strength

THE EFFECT OF NUMBERS OF REPETITIONS ON PEAK TORQUE IN ROWER ANS NON-ATHLETE FEMALES WHEN USING ISOKINETIS TESTING

Isokinetic training has been used as a successful means for testing and increasing muscle strength. The purpose of this study was to investigate the effect that different numbers of repetitions have on fatigue and force generation in females and specifically between athletes and non-athletes. Thirty college-aged females (15 rowers, 15 non-athletes) were tested using an isokinetic machine to measure peak torque. Each subject was tested 5-6 times on the isokinetic machine. This included 1-2 familiarization tests and four experimental testing sessions during which subjects performed randomly assigned maximal knee extensions of either four, six, eight, or ten repetitions, through a 90 degree range of motion, at 60, 120, 180, 240, and 300deg/s. Rest periods between velocities were kept constant at 60 sec. Using SPSS 14.0 data were analyzed using a 2 X 4 X 5 repeated measures ANOVA with alpha < .05. Group, repetitions, and velocity served as the independent variables and peak torque as the dependent variable. Peak torque in rowers was also compared to the time taken to complete a 2000m distance on a rowing ergometer. No significant difference was found between the various repetitions at different velocities. A significant difference was found between peak torques at the different velocities (F=1221.37,

Reduction of laser intensity scintillations in turbulent atmospheres using time averaging of a partially coherent beam

We demonstrate experimentally and numerically that the application of a partially coherent beam (PCB) in combination with time averaging leads to a significant reduction in the scintillation index. We use a simplified experimental approach in which the atmospheric turbulence is simulated by a phase diffuser. The role of the speckle size, the amplitude of the phase modulation, and the strength of the atmospheric turbulence are examined. We obtain good agreement between our numerical simulations and our experimental results. This study provides a useful foundation for future applications of PCB-based methods of scintillation reduction in physical atmospheres.Comment: 18 pages, 14 figure

How model sets can be determined by their two-point and three-point correlations

We show that real model sets with real internal spaces are determined, up to translation and changes of density zero by their two- and three-point correlations. We also show that there exist pairs of real (even one dimensional) aperiodic model sets with internal spaces that are products of real spaces and finite cyclic groups whose two- and three-point correlations are identical but which are not related by either translation or inversion of their windows. All these examples are pure point diffractive. Placed in the context of ergodic uniformly discrete point processes, the result is that real point processes of model sets based on real internal windows are determined by their second and third moments.Comment: 19 page

Final design proposal: Delta Group-Nood Rider 821(tm)

The Nood Rider 821 (trademark) twin-engine, prop passenger aircraft is described. It is argued that the aircraft is very economical to operate and maintain, offering competitive advantages in the air travel marketplace. The aircraft was designed to operate in 'Aeroworld', a fictional world where the passengers are ping pong balls and the distances between cites are on the order of thousands of feet

Effect of ethanol and of noise on reaction time in the monkey: Variation with stimulus level

To determine whether the latency-increasing effects of ethanol were differential with respect to the intensity of the stimulus that initiated the response, three rhesus monkeys were trained on a behavioral task in which the latency of a simple motor response was measured following the onset of a pure tone stimulus. Following training, the animals were tested at a number of different tone intensities and functions relating latency to tone intensity were constructed. When these were stable, the animals were given ethanol in doses of 1.0–2.5 g/kg and the effects on response latencies to different tone intensities were determined. It was found that, for all except the lowest stimulus levels, the effect of ethanol was dose-related, while for a given dose the effect was equal across intensity. These results indicate that the effects of ethanol in this situation are on response execution rather than stimulus detection. The effects of ethanol were compared to those of exposure to high intensity noise. This treatment, which affects primarily the inner ear, resulted in substantial increases in latency to low intensity tones, but little, if any, shift at high intensities.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46413/1/213_2004_Article_BF00426520.pd

From solid solution to cluster formation of Fe and Cr in α\alpha-Zr

To understand the mechanisms by which Fe and Cr additions increase the corrosion rate of irradiated Zr alloys, a combination of experimental (atom probe tomography, x-ray diffraction and thermoelectric power measurements) and modelling (density functional theory) techniques are employed to investigate the non-equilibrium solubility and clustering of Fe and Cr in binary Zr alloys. Cr occupies both interstitial and substitutional sites in the {\alpha}-Zr lattice, Fe favours interstitial sites, and a low-symmetry site that was not previously modelled is found to be the most favourable for Fe. Lattice expansion as a function of alloying concentration (in the dilute regime) is strongly anisotropic for Fe additions, expanding the $c$-axis while contracting the $a$-axis. Defect clusters are observed at higher solution concentrations, which induce a smaller amount of lattice strain compared to the dilute defects. In the presence of a Zr vacancy, all two-atom clusters are more soluble than individual point defects and as many as four Fe or three Cr atoms could be accommodated in a single Zr vacancy. The Zr vacancy is critical for the increased solubility of defect clusters, the implications for irradiation induced microstructure changes in Zr alloys are discussed.Comment: 15 pages including figure, 9 figures, 2 tables. Submitted for publication in Acta Mater, Journal of Nuclear Materials (2015

Shock waves in superfluid helium

Exact solutions of the equations of motion of liquid helium II can be compared to experiments to test Landau's two-fluid theory. The best flows with which to conduct such tests are those in which amplitudes and gradients are large and in which the calculations and measurements are free from wall effects, e.g., shock waves. The four fundamental conservation equations of superfluid mechanics have been integrated across a one-dimensional discontinuity (shock wave) propagating into undisturbed helium II to yield a set of four algebraic equations (jump conditions) which, when supplemented by thermodynamic state information, establish the equilibrium flow state behind the shock wave for a given wave speed and undisturbed flow state ahead of the shock. These jump conditions have been solved numerically for 19 points on the helium II p-T diagram with upstream Mach number as the independent parameter. Representative results of the calculations are presented for pressure shocks, temperature raising shocks, and temperature lowering shocks. The results are compared to previous analytical approximate solutions to test the validity of those approximations. They are also compared to experimental data for shock waves in helium II as a means of testing the correctness of the full nonlinear two-fluid equations

Recent Progress in Vector Vortex Coronagraphy

The optical vortex coronagraph has great potential for enabling high-contrast observations very close to bright stars, and thus for reducing the size of space telescopes needed for exoplanet characterization missions. Here we discuss several recent developments in optical vortex coronagraphy. In particular, we describe multi-stage vortex configurations that allow the use of on-axis telescopes for high-contrast coronagraphy, and also enable the direct measurement of the amplitudes and phases of focal plane speckles. We also briefly describe recent laboratory demonstrations of the optical properties of the dual-stage vortex, and of the broadband performance of single stage vortex masks. Indeed, the demonstrated performance of the vector vortex phase masks already in hand, ≈ 10^(-8), is approximately that needed for an initial coronagraphic mission, such as an exoplanet explorer, aimed at detecting exozodiacal light and jovian exoplanets