EFFECT OF KINEMATIC VARIABLES ON ENTRY PHASE IN COMPETITIVE SWIMMINGSTART

INTRODUCTION: Starting techniques are one of the most important factors for race performance in competitive swimming. Start phase (0-15m) is classified Block phase, Flight phase, Entry phase, Glide phase and Stroke phase. There are many study about effect of Kinematics and Kinetics variables on Block phase and Flight phase entry in competitive swimming start. However, there have been very few studies about the techniques of an Entry phase. The relationship between start techniques and performances of entry phase has not been clarified. Therefore, the purpose of this study was to investigate the effect of different entry methods on the performance of the entry phase

KINEMATIC CHARACTERISTICS OF KICK START FOR ELITE COMPETITIVE JAPANESE MALE SPRINT SWIMMERS

The purpose of this study was to compare the kinematic characteristics of the kick start technique at the start phase demonstrated by male elite competitive sprint swimmers and male collegiate swimmers in consideration of the performance enhancement. An elite competitive sprint swimmer and eleven collegiate male swimmers performed maximal effort during competitive swimming at the start followed by 25 m crawl swim during experimental trials. The trials were recorded using three synchronized video cameras shooting at 60 fps. Two-dimensional video analysis was performed in the sagittal plane. Calculated variables at take-off were horizontal velocity, speed, attitude angle, angle of projection, whereas those at entry were entry angle, attitude angle, angle of attack. In addition, block time horizontal coordinates for start position and 15 m time were calculated. Based on the results of this study, the kick start technique for the top competitive sprint swimmer was characterized as having shorter block time and higher horizontal velocity at take-off

KICKING THE BACK PLATE OF THE STARTING BLOCK IMPROVES START PHASE PERFORMANCE IN COMPETITIVE SWIMMING

Kinematic characteristics and performance were evaluated during the start phase using two start techniques (kick start and track start) in 11 male elite collegiate swimmers. Trials were recorded using three synchronized video cameras shooting at 60 fps. Twodimensional video analysis was performed in the sagittal plane. Paired t-test was used to compare variables between the two techniques. The block time (kick start 0.70 ±0.04 s, track start 0.74 ±0.04 s,

ROLES OF THE EXTREMITIES DURING KICK START IN COMPETITIVE SWIMMING

This study was aimed at examining the role of the hands and feet at takeoff by measuring the forces applied to the starting block by the right/left hands and feet. A small, waterproof force plate and a three-axis force sensor (operating at 500 Hz) were placed at the front and back of a custom-made starting block with an inclination angle of 10�� and on the right and left sides of the front of the starting block, respectively, to measure the force exerted on the starting block. Five male collegiate competitive swimmers were requested to perform kick starts from the starting block. The rear and front feet had the greatest contribution to the horizontal and vertical velocities, respectively, at kick start. In addition, the hand and foot exerted downward and upward forces, respectively, to the vertical velocity at kick start, revealing bilateral differences in the horizontal and vertical velocities of the hand

Adaptive Melanin Response of the Soil Fungus Aspergillus niger to UV Radiation Stress at “Evolution Canyon”, Mount Carmel, Israel

BACKGROUND:Adaptation is an evolutionary process in which traits in a population are tailored by natural selection to better meet the challenges presented by the local environment. The major discussion relating to natural selection concerns the portraying of the cause and effect relationship between a presumably adaptive trait and selection agents generating it. Therefore, it is necessary to identify trait(s) that evolve in direct response to selection, enhancing the organism's fitness. "Evolution Canyon" (EC) in Israel mirrors a microcosmic evolutionary system across life and is ideal to study natural selection and local adaptation under sharply, microclimatically divergent environments. The south-facing, tropical, sunny and xeric "African" slope (AS) receives 200%-800% higher solar radiation than the north-facing, temperate, shady and mesic "European" slope (ES), 200 meters apart. Thus, solar ultraviolet radiation (UVR) is a major selection agent in EC influencing the organism-environment interaction. Melanin is a trait postulated to have evolved for UV-screening in microorganisms. Here we investigate the cause and effect relationship between differential UVR on the opposing slopes of EC and the conidial melanin concentration of the filamentous soil fungus Aspergillus niger. We test the working hypothesis that the AS strains exhibit higher melanin content than strains from the ES resulting in higher UV resistance. METHODOLOGY/PRINCIPAL FINDINGS:We measured conidial melanin concentration of 80 strains from the EC using a spectrophotometer. The results indicated that mean conidial melanin concentration of AS strains were threefold higher than ES strains and the former resisted UVA irradiation better than the latter. Comparisons of melanin in the conidia of A. niger strains from sunny and shady microniches on the predominantly sunny AS and predominantly shady ES indicated that shady conditions on the AS have no influence on the selection on melanin; in contrast, the sunny strains from the ES displayed higher melanin concentrations. CONCLUSIONS/SIGNIFICANCE:We conclude that melanin in A. niger is an adaptive trait against UVR generated by natural selection

Inactivation of Pmel Alters Melanosome Shape But Has Only a Subtle Effect on Visible Pigmentation

PMEL is an amyloidogenic protein that appears to be exclusively expressed in pigment cells and forms intralumenal fibrils within early stage melanosomes upon which eumelanins deposit in later stages. PMEL is well conserved among vertebrates, and allelic variants in several species are associated with reduced levels of eumelanin in epidermal tissues. However, in most of these cases it is not clear whether the allelic variants reflect gain-of-function or loss-of-function, and no complete PMEL loss-of-function has been reported in a mammal. Here, we have created a mouse line in which the Pmel gene has been inactivated (Pmel−/−). These mice are fully viable, fertile, and display no obvious developmental defects. Melanosomes within Pmel−/− melanocytes are spherical in contrast to the oblong shape present in wild-type animals. This feature was documented in primary cultures of skin-derived melanocytes as well as in retinal pigment epithelium cells and in uveal melanocytes. Inactivation of Pmel has only a mild effect on the coat color phenotype in four different genetic backgrounds, with the clearest effect in mice also carrying the brown/Tyrp1 mutation. This phenotype, which is similar to that observed with the spontaneous silver mutation in mice, strongly suggests that other previously described alleles in vertebrates with more striking effects on pigmentation are dominant-negative mutations. Despite a mild effect on visible pigmentation, inactivation of Pmel led to a substantial reduction in eumelanin content in hair, which demonstrates that PMEL has a critical role for maintaining efficient epidermal pigmentation

A Rare Nodular Fasciitis Involving the Finger: A Case Report

This is a report of a 43-year-old man with nodular fasciitis of the little finger. Nodular fasciitis with its feature of rapid growth and aggressive histological appearance is often mistaken for a malignant neoplasm and rarely involves fingers