The Effect of Mental Training on Motor Performance of Tennis and Field Hockey Strokes in Novice Players

The aim of this study was to investigate whether the mental training of motor performance can be useful or not in learning tennis and field hockey strokes (forehand, backhand; push pass, hit) Twenty four male tennis-field hockey novice players participated in the study and were divided into experimental group (N = 12) and group for the scientific treatment of the tests (N = 12). Subjects were recruited from Faculty of Physical Education for Men, Alexandria University, Egypt, with ages between 19 to 20 years old. The experimental group attended 16 sessions (8 for tennis, 8 for field hockey) over six weeks (40 minutes each) and used mental training exercises (relaxation, visualization and concentration-attention control) pertinent to the forehand, backhand in tennis and push pass, hit in field hockey. Two waves of measurements were conducted (before and after the completion of the intervention) with the use of motor assessment tests related to the sport of tennis and field hockey. Each student was evaluated regarding to his technique of forehand, backhand in tennis and push pass, hit in field hockey in order to examine the effectiveness of mental training. Questionnaires were also used to measure visualization and concentration-attention control. The results showed a highly significant improvement in learning forehand, backhand in tennis and push pass in field hockey. However, no statistical difference was found for the performance of the hit stroke in field hockey. In addition, the findings showed also a significant difference between the initial and the final measurement regarding to the ability of concentration and visualization by using questionnaires. The results revealed a value of 0.780 which indicates a good reliability of the tool. As a conclusion, a combination of mental and practical training promises the greatest improvement in performance and learning, because it involves all senses

Model for Small neutrino masses at the TeV Scale

We propose a model for neutrino mass generation in wich no physics beyond a TeV is required. We extend the standard model by adding two charged singlet fields with lepton number two. Dirac neutrino masses $m_{\nu_D} \leq MeV$ are generated at the one loop level. Small left handed majorana neutrino masses can be generated via the seesaw mechanism with right handed neutrino masses $M_R$ are of order TeV scale.Comment: 13 pages, 2 figure

Solid State Amorphization Reaction by Rod-Milling Al_xTa_<1-x> Powders and the Effect of Annealing

High thermal stable amorphous Al_xTa_ alloy powders with wide amorphization range (10≤x≤90) have been synthesized by rod-milling technique using a mechanical alloying (MA) method. During the first few kiloseconds (11-173 ks) of the MA time, the layered-composite particles of Al and Ta are intermixed and form an amorphous phase upon heating at about 680 K in a differential thermal analyzer by thermally assisted solid state amorphization (TASSA). The heat formation of an amorphous Al_xTa_ alloy via the TASSA process, ΔH_ has been measured as a function of the MA time. The crystallization characteristics indexed by the crystallization temperature, T_ and the enthalpy of crystallization, ΔH_ of the amorphous phase formed via the TASSA process are also investigated as a function of the MA time. Comparable with the TASSA process, a homogeneous amorphous Al_xTa_ alloy is formed after longer MA time (1080 ks). The amorphization process in this case is attributed to a mechanical solid state amorphization (MDSSA). At the end of the MA time (1080-1440 ks), the maximum heat of formation of an amorphous Al_xTa_ alloy via the MDSSA process, ΔH_, has been calculated. Moreover, the thermal stability characterized by the crystallization temperature, T_ and the enthalpy of crystallization, ΔH_, are also estimated. The role of amorphization via each process has been discussed

Horizon area bound and MOTS stability in locally rotationally symmetric solutions

In this paper, we study the stability of marginally outer trapped surfaces (MOTS), foliating horizons of the form $r=X(\tau)$, embedded in locally rotationally symmetric class II perfect fluid spacetimes. An upper bound on the area of stable MOTS is obtained. It is shown that any stable MOTS of the types considered in these spacetimes must be strictly stably outermost, that is, there are no MOTS ``outside" of and homologous to $\mathcal{S}$. Aspects of the topology of the MOTS, as well as the case when an extension is made to imperfect fluids, are discussed. Some non-existence results are also obtained. Finally, the ``growth" of certain matter and curvature quantities on certain unstable MOTS are provided under specified conditions.Comment: 21 pages, Submitted to CQG, comments are welcom

Elucidation of the effects of a high fat diet on trace elements in rabbit tissues using atomic absorption spectroscopy

<p>Abstract</p> <p>Background</p> <p>The mechanism of atherogenesis is not yet fully understood despite intense study in this area. The effects of high fat diet (HFD) on the changes of trace elements [iron (Fe), copper (Cu) and zinc (Zn)] in several tissues of rabbits have not been documented before. Thus, the aim of this study was to elucidate the changes in trace elements in several tissues of rabbits fed on HFD for a period of feeding of 10 weeks.</p> <p>Results</p> <p>The HFD group was fed a NOR rabbit chow supplemented with 1.0% cholesterol plus 1.0% olive oil. Fe, Cu and Zn concentrations were measured in four types of tissue from control and HFD rabbits using atomic absorption spectroscopy (AAS). Comparing HFD rabbits to control rabbits, we found that the highest percentage change of increase of Fe was 95% in lung tissue, while the lowest percentage change of increase of Fe was 7% in kidney tissue; the highest percentage change of decrease of Cu was 16% in aortic tissue, while the lowest percentage change of decrease of Cu was 6% in kidney tissue; and the highest percentage change of decrease of Zn was 71% in kidney tissue, while the lowest percentage change of decrease of Zn was 8% in lung tissue.</p> <p>Conclusions</p> <p>These results suggest that Fe plays a major role in atherogenesis; it may accelerate the process of atherosclerosis probably through the production of free radicals, deposition and absorption of intracellular and extracellular lipids in the intima, connective tissue formation, smooth muscle proliferation, lower matrix degradation capacity and increased plaque stability. Furthermore, inducing anemia in HFD rabbits may delay or inhibit the progression of atherosclerosis. Cu plays a minor role in atherogenesis and Cu supplements may inhibit the progression of atherogenesis, perhaps by reducing the migration of smooth muscle cells from the media to the intima. Zn plays a major role in atherogenesis and that it may act as an endogenous protective factor against atherosclerosis perhaps by reducing lesion Fe content, intracellular and extracellular lipids in the intima, connective tissue formation, and smooth muscle proliferation. These results suggest that it may be possible to use the measurement of changes in trace elements in different tissues of rabbits as an important risk factor during the progression of atherosclerosis.</p

End Zone Reinforcement for Pretensioned Concrete Girders

In this study, a literature review was conducted to establish the background of current specifications and to evaluate the applicability of various theories and methods for design of end zone reinforcement. Analytical methods reviewed in this paper include finite element analysis, strut-and-tie modeling, and the Gergely-Sozen equivalent beam method. Previous experimental work combined with work conducted as part of this study was used to correlate between various theoretical and experimental results. This paper illustrates that no single theoretical method adequately represents the complex behavior at the end of a pretensioned concrete member. A general semi-empirical design procedure is proposed here. It is based on theoretical behavior and experimental observation. Standard reinforcement details are given. The proposed procedure could result in significant reduction in the amount of reinforcement while maintaining acceptable crack control at the member end. Application of the proposed procedure to highly pretensioned bridge girders is demonstrated