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981.
Test procedures and their accuracy in determining critical fall height (CFH) on sporting grounds are paramount to player safety.
The procedure currently adopted for synthetic turf in Australian football [1] consists of four consecutive drops at various drop heights at three test locations on the sample. The quantity and packing
of the infill in third-generation turf and the pooling effect of the rubber particles with consecutive drops suggests that
the current standard protocol may need re-assessment. Therefore, the purpose of this pilot study was to investigate whether
current methods of testing for CFH are appropriate for third-generation synthetic turf or whether an alternative or adapted
method needs to be developed. CFH was measured, using a HISUN Uniaxe-II Impact Tester, on 12 combinations of synthetic turf
samples (four different products with three shock pad options). Three conditions were investigated on each sample; the existing
protocol; an alternative 12 single-drop protocol and four single drops from the CFH determined from the existing protocol.
A significant difference was found for both absolute and percentage difference between the existing and 12 single-drop protocol,
with p = 0.001 and t = 4.33 and p < 0.001 and t = 6.03, respectively. There was also a significant difference between the CFH reached with and without a shock pad for both
the existing protocol and the 12 single-drop protocol. The results of this pilot study demonstrate that differences do occur
with alterations to the existing protocol and highlight the need for a more detailed characterisation of testing methods on
third-generation synthetic turf and the response of surfaces to them. 相似文献
982.
A number of recent studies have measured the extent and timing of segment rotation during the golf swing. A promising technique,
instantaneous screw axis (ISA) theory, could provide a better expression of segment rotation. In Part 1 of this two-part study,
the objectives are to identify the ISA of the pelvis, shoulders and left arm during the downswing, compute segment angular
velocity relative to that segment’s ISA and verify that ISA theory is a valid tool to analyse segment rotation during the
golf swing. Results indicate that for all subjects, at least 71% of marker velocity is a result of rotation about their respective
ISA, when averaging results over the duration of the downswing, confirming that motion is primarily rotational. Furthermore,
ISA position and orientation of each segment approaches, on average, the expected gross axis of rotation, confirming that
motion about the ISA is representative of joint motion. 相似文献
983.
研究以奥运争光类竞技体育服务产品的提供方式为对象,通过对我国传统竞技体育服务产品提供方式的历史考察发现,举国体制是我国传统竞技体育服务产品提供的重要方式之一。在现实条件下,奥运争光竞技体育服务产品的提供具有多元可能性,而专项资金、资助高校培养模式、委托生产——合约模式、非营利组织生产等方式。 相似文献
984.
Kevin King N. C. Perkins Hugh Churchill Ryan McGinnis Ryan Doss Ron Hickland 《Sports Engineering》2011,13(2):95-104
This paper presents a novel sensor technology to deduce the dynamics of a bowling ball. The sensor, a miniature wireless inertial
measurement unit (IMU), incorporates MEMS accelerometers and angular rate gyros, a microcontroller, a low power RF transceiver,
and a rechargeable battery. When embedded in a bowling ball, the IMU transmits the acceleration and angular velocity data
that define the dynamics of the ball starting with the bowler’s delivery and its motion in the lane. Example results from
professional bowlers illustrate how this technology can be used to assess bowler skill and ball performance. For instance,
the IMU accurately measures the spin dynamics of the ball which are crucial to develop the ball “hook.” An analysis of ball
dynamics in the lane is distilled to a measurable “hook potential” metric for further assessing bowler skill. Finally, the
sensor presented herein is believed to be the world’s smallest, wireless IMU. This highly miniaturized and wireless design
will enable parallel training systems for many sports, including basketball, baseball, crew, cricket, golf, fly fishing, soccer,
softball, tennis, rowing, among others. 相似文献
985.
Daniel Torres-Salinas lvaro Cabezas-Clavijo Rafael Ruiz-Prez Emilio Delgado Lpez-Czar 《Library & information science research》2011,33(2):168-174
A metric analysis of blogs on library and information science (LIS) between November 2006 and June 2009 indexed on the Libworm search engine characterizes the community's behavior quantitatively. An analysis of 1108 personal and corporate blogs with a total of 275,103 posts is used to calculate survival rate, production (number of posts published), and visibility via such indicators as links received, Technorati authority, and Google's PagePank. Over the study period, there was a 52% decrease in the number of active blogs. Despite the drop in production over this period, the average number of posts per blog remained constant (14 per month). The most representative blogs in the discipline are identified. The emergence of such platforms as Facebook and Twitter seems to have meant that both personal and corporate blogs have lost some of their prominence. 相似文献
986.
P-selectin, a cell adhesion molecule is elevated in many inflammatory conditions including preeclampsia which is characterized
by generalized endothelial dysfunction and vasoconstriction presumably due to free radicals or mediators released by defective
placentation. Vitamin E has been documented to protect cell membranes from oxidative damage and also decrease platelet aggregation.
The role of vitamin E in pre-eclampsia is contradictory and hence the study was undertaken. Soluble P-selectin was measured
by ELISA and Vitamin-E levels in plasma was estimated spectrofluorometrically. In our study the effect of supplementation
of 400 IU/day of Vitamin E (a-tocopheryl acetate) to patients of pre-eclampsia showed significant decreased levels of soluble
P-selectin by 2nd week as compared to patients given placebo (P = 0.005). In this short period of study no direct correlations were observed between Vitamin E or P-selectin levels with
blood pressure as well as with proteinuria. Future studies may focus on the effect of a-tocopheryl acetate or the phosphate
form of Vitamin-E, recently proposed to be the more active form on other inflammatory markers like IL-6, an important stimuli
of P-selectin release in pre-eclampsia. 相似文献
987.
Venkateshwari A Sri Manjari K Krishnaveni D Nallari P Vidyasagar A Jyothy A 《Indian journal of clinical biochemistry : IJCB》2011,26(2):136-139
Pancreatic fibrosis is a key pathological feature in the etiology of chronic pancreatitis that leads to obliteration of exocrine
and endocrine pancreatic tissues and its replacement by fibrous tissue resulting in clinical manifestations. Matrix metalloproteinase
9 is a member of the MMP family that is also known as gelatinase B, degrades type IV collagen of extracellular matrix and
basal membrane. The present study is aimed at evaluating the clinical significance of plasma concentration of MMP-9 in chronic
pancreatitis. The samples were obtained from 112 chronic pancreatitis patients and an equal number of age and sex matched
healthy controls. MMP-9 levels were quantitatively measured by ELISA assay. Statistical analysis was applied to test the significance
of results. The present study revealed a significant increase of plasma MMP 9 levels in chronic pancreatitis patients compared
to control subjects. Elevated levels were also observed in all the patient groups compared to control subjects with regard
to sex, age, addictions etc. MMP-9 degrades the type IV collagens in normal basement membrane, which in turn activates the
pancreatic stellate cells which promote the development of pancreatitic fibrosis. Thus, elevated plasma levels of MMP-9 may
act as a susceptibility factor for the development of chronic pancreatitis. 相似文献
988.
Kannan Vaidyanathan M. P. Narayanan D. M. Vasudevan 《Indian journal of clinical biochemistry : IJCB》2011,26(4):319-325
Organic acidurias are an important class of inherited metabolic disorders arising due to defect in intermediary metabolic
pathways of carbohydrate, amino acids and fatty acid oxidation. This review summarizes the current knowledge about the important
organic acidurias in the Indian population. Specifically, diagnosis and principles of treatment of organic acidurias are covered.
The salient features of common organic acidurias as well as their prevalence in various parts of the world are reviewed in
some detail. 相似文献
989.
Haruhiro Muratsubaki Akiko Yamaki 《Indian journal of clinical biochemistry : IJCB》2011,26(4):416-419
The effect of acute hypoxic hypoxia on the profile of plasma amino acids in rats was studied and compared to that resulting
from acute liver injury induced by giving carbon tetrachloride. In hypoxic rats exposed to 45% air in N2 for 5 h, the concentrations of branched chain amino acids, including valine, leucine and isoleucine, and aromatic amino acids
such as phenylalanine and tyrosine were significantly increased as compared to those in normoxic rats. The ratio of branched-chain
to aromatic amino acids (Fischer’s ratio) was significantly decreased. The levels of arginine and citrulline, which are related
to the urea cycle, were also depressed. Furthermore, plasma proline level was reduced in hypoxic rats. The activities of plasma
marker enzymes for tissue damage remained unchanged during hypoxia, indicating that tissue injury was not induced by exposure
to hypoxic conditions. We suggest that the characteristic profile of plasma amino acids and the Fischer ratio are valuable
tools for understanding the pathology of acute hypoxia in the absence of systemic tissue damage. 相似文献
990.