THE OPTIMAL PLYOMETRIC EXERCISE HORIZONTAL TO VERTICAL FORCE RATIO FOR SPRINTING

This study determined the horizontal to vertical force ratio (H:V) of two types of sprint starts and a variety of plyometric exercise, for the purpose of determining the exercises which are most biomechanically specific to sprinting. Subjects included 15 men. All subjects’ performed the sprinter start, the standing sprint start, the CMJ, 18 inch hurdle hop, bounding, power skipping, standing long jump, and multiple hops, starting on a force platform. A repeated measures ANOVA was used to determine differences in H:V between the sprinter start, the standing start, and the plyometric exercises. Results reveal significant main effects for sprint start H:V and standing start H:V, and the plyometric exercises H:V (p ≤ 0.001). Post-hoc analyses revealed that bounding and standing long jumps are the most biomechanically for training athletes for sprint starts

Late Viséan pelagic chondrichthyans from northern Europe

The relatively rich assemblages of shark teeth from pelagic limestone (Mississippian, late Viséan, late Asbian–middle Brigantian) of three northern European regions: the Rhenish Mountains (Westenfeld Quarry, Germany), the Holy Cross Mountains (Todowa Grz ą ba at the edge of Ostrówka Quarry, Poland), and Derbyshire (Cawdor Quarry, Matlock, England, UK) display certain similarities, with the absolute predominance of the teeth of Falcatidae (small Symmoriiformes) and the constant presence of Thrinacodus spp. The largest and most diverse assemblage from Todowa Grz ą ba contains at least three species of a falcatid Denaea , a xenacanthimorph Bransonella nebraskensis , a newly described phoebodontid Thrinacodus dziki sp. nov., a few ctenacanthiform and euselachian teeth, and two abraded euchondrocephalan dental elements. Anachronistidae, common in the most of late Viséan pelagic faunas, are absent from Todowa Grz ą ba and Westenfeld. The material under study differs from the shallow-water chondrichthyan fauna, hitherto described from the Mississippian carbonate platform facies, by its taxonomic content (particularly almost total absence of Euchondro- cephali), generally lower diversity, and higher frequency of small teet

Impact of taxane-based chemotherapeutics on male reproductive function

Men and boys with cancer treated with chemotherapy are known to have reduced fertility following their treatment. This is because some chemotherapy drugs can damage the cells in the testicles that make sperm. This study found there is limited information available on the effect of one group of chemotherapy drugs, called taxanes, on testicular function and fertility. More studies are needed to aid clinicians in advising patients on how this taxane-based chemotherapy may affect their future fertility

Exact solution for random walks on the triangular lattice with absorbing boundaries

The problem of a random walk on a finite triangular lattice with a single interior source point and zig-zag absorbing boundaries is solved exactly. This problem has been previously considered intractable.Comment: 10 pages, Latex, IOP macro

On the truncation of the harmonic oscillator wavepacket

We present an interesting result regarding the implication of truncating the wavepacket of the harmonic oscillator. We show that disregarding the non-significant tails of a function which is the superposition of eigenfunctions of the harmonic oscillator has a remarkable consequence: namely, there exist infinitely many different superpositions giving rise to the same function on the interval. Uniqueness, in the case of a wavepacket, is restored by a postulate of quantum mechanics

MULTI-PLANAR ANALYSIS OF THE TRADITIONAL BACK SQUAT AND SMITH MACHINE BACK SQUAT

This study evaluated the kinetic differences between the traditional back squat (T-BS) and Smith machine back squat (SM-BS) performed at a variety of loads. Ten subjects were tested in six conditions including the T-BS and SM-BS each performed at 50%, 80%, and 100% of the subject’s five repetition maximum load on a force platform. The analysis of vertical ground reaction forces (GRF) revealed significant main effects for exercise load (p ≤ 0.001) but not for squat condition or the interaction of load and squat condition (p \u3e 0.05). The analysis of sagittal plane GRF revealed significant main effects for exercise load (p ≤ 0.05), squat condition (p ≤ 0.001), and the interaction between load and condition (p ≤ 0.05). The analysis of frontal plane GRF revealed no main effects (p \u3e 0.05). The SM-BS offers the user a resistance stimuli in the sagittal plane against which the exerciser can produce greater sagittal force

Simulations of Coherent Synchrotron Radiation on Parallel Hybrid GPU/CPU Platform

Coherent synchrotron radiation (CSR) is an effect of self-interaction of an electron bunch as it traverses a curved path. It can cause a significant emittance degradation, as well as fragmentation and microbunching. Numerical simulations of the 2D/3D CSR effects have been extremely challenging due to computational bottlenecks associated with calculating retarded potentials via integrating over the history of the bunch. We present a new high-performance 2D, particle-in-cell code which uses massively parallel multicore GPU/GPU platforms to alleviate computational bottlenecks. The code formulates the CSR problem from first principles by using the retarded scalar and vector potentials to compute the self-interaction fields. The speedup due to the parallel implementation on GPU/CPU platforms exceeds three orders of magnitude, thereby bringing a previously intractable problem within reach. The accuracy of the code is verified against analytic 1D solutions (rigid bunch) and semi-analytic 2D solutions for the chirped bunch. Finally, we use the new code in conjunction with a genetic algorithm to optimize the design of a fiducial chicane

Random walks on finite lattice tubes

Exact results are obtained for random walks on finite lattice tubes with a single source and absorbing lattice sites at the ends. Explicit formulae are derived for the absorption probabilities at the ends and for the expectations that a random walk will visit a particular lattice site before being absorbed. Results are obtained for lattice tubes of arbitrary size and each of the regular lattice types; square, triangular and honeycomb. The results include an adjustable parameter to model the effects of strain, such as surface curvature, on the surface diffusion. Results for the triangular lattice tubes and the honeycomb lattice tubes model diffusion of adatoms on single walled zig-zag carbon nano-tubes with open ends.Comment: 22 pages, 4 figure

KINETIC AND SEX-BASED ANALYSIS OF THE TRADITIONAL AND HORIZONTAL HANG CLEAN

The horizontal hang clean (H-HC) is a novel variation of the traditional hang clean (T-HC). This study evaluated the H-HC and T-HC and compared the horizontal and vertical ground reaction forces and the ratio of those forces (H:V), to the horizontal and vertical ground reaction forces and H:V of the countermovement jump (CMJ) and standing sprint start (SSS). Ten men and ten women NCAA Division III athletes performed the T-HC, H-HC, CMJ, and SSS on a force platform. Results revealed that the H-HC produced a significantly (p ≤ 0.001) greater H:V than the T-HC. There was no interaction between any of these variables and sex (p \u3e 0.05). The H-HC should be included in training programs of men and women to increase the likelihood of transfer of training to activities such as sprinting