Formation process of talented tennis players

O objetivo do presente estudo foi obter informações a respeito do processo de formação de \ud tenistas talentosos e os consequentes fatores que contribuíram para o alcance do profissionalismo. Para \ud tanto, se utilizou uma amostra de cinco tenistas brasileiros profissionais, caracterizados por terem pontos na \ud ATP (Associação dos Tenistas Profissionais). A pesquisa foi constituída através de um delineamento \ud qualitativo, que utilizou como instrumento uma entrevista composta por três perguntas abertas, elaboradas \ud para explorar o contexto de formação do talento. Para a análise dos resultados foi utilizado o “Discurso do \ud Sujeito Coletivo”. De acordo com os resultados, pode-se observar a importância que os professores tiveram \ud no desenvolvimento destes tenistas talentosos, tanto na iniciação como no treinamento. No que se diz \ud respeito ao planejamento dos treinos, o presente estudo demonstra a falta de profissionalismo nas fases \ud iniciais do processo de formação, e a posterior preocupação apenas quando este atleta demonstra possuir \ud algum potencial para seguir carreira profissional.The objective of this study was to obtain information about the formation process of talented players and the factors that contributed to their professionalism. We used a sample of five Brazilian professional tennis players, with significant scores earned at the ATP (Association of Tennis Professionals). The study was conducted using a qualitative research design, which used as an instrument interview consisting of three open-ended questions designed to explore the context of training talent in tennis. For the analysis of the results we used the "Collective Subject Discourse." According to the results, we observed the importance instructors have in developing these talented players during the early and the later training process. With regard to the planning of the training sessions, this study demonstrates the lack of professionalism in the early stages of the training process and the primary concern with the athlete's professional career potential

Diseño de losas flotantes para montaje de equipos sensibles a vibraciones en naves industriales

Cada vez es más frecuente la utilización de equipamiento moderno y sensible en plantas industriales, donde los niveles de vibraciones son altos. Las instalaciones deben cumplir con las especificaciones de los fabricantes de las máquinas en cuanto a los límites máximos tolerados, lo que puede conseguirse con montajes adecuados. Una solución alternativa al montaje elástico directo o aislamiento individual para cada equipo, es optar por superficies aisladas o losas flotantes, lo que provee una mayor flexibilidad al layout. Para el diseño de losas flotantes son utilizados habitualmente modelos simplificados de un grado de libertad, despreciando la influencia de la flexibilidad flexional de las losas y la contribución a la respuesta de los modos flexionales. La excitación de base rígida es además una simplificación frente a la excitación real consistente en trenes de ondas propagadas por la superficie de base donde apoyan los aisladores. En el presente trabajo se investiga la respuesta dinámica de losas aisladas contra vibraciones y excitadas desde la base y a través del sistema de aislamiento, por ondas superficiales propagadas en el semiespacio homogéneo de suelo, teniendo además en cuenta la flexibilidad de las losas. La efectividad del aislamiento se cuantifica a partir de los desplazamientos máximos de la losa calculados en el dominio de la frecuencia para una excitación con ancho de banda dentro del rango de interés de los equipamientos comerciales típicos. El análisis comienza por la transmisibilidad de vigas resuelta en forma analítica, de lo que surge el concepto de transmisibilidad modal y transmisibilidad modal envolvente. Estos parámetros provenientes de una estructura unidimensional resultan convenientes para ser utilizados como referencia en el diseño de losas flotantes industriales. A modo de ejemplo se estudió una sala de metrología para la cual se contrastaron resultados provenientes de un análisis por elementos finitos con los obtenidos con el modelo de viga equivalente aquí propuesto.Fil: Stuardi, José Enrique. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Departamento de Estructuras; Argentina;Fil: Ceballos, Marcelo Alejandro. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Departamento de Estructuras; Argentina;Fil: Ritta, Raúl José. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Departamento de Estructuras; Argentina;Fil: Massa, Julio Cesar. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Departamento de Estructuras; Argentina

Is the technical performance of young soccer players influenced by hormonal status, sexual maturity, anthropometric profile, and physical performance?

The aim of this study was to examine the influence of hormonal status, anthropometric profile, sexual maturity level, and physical performance on the technical abilities of 40 young male soccer players during small-sided games (SSGs). Anthropometric profiling, saliva sampling, sexual maturity assessment (Tanner scale), and physical performance tests (Yo-Yo and vertical jumps) were conducted two weeks prior to the SSGs. Salivary testosterone was determined by the enzyme-linked immunosorbent assay method. Technical performance was determined by the frequency of actions during SSGs. Principal component analyses identified four technical actions of importance: total number of passes, effectiveness, goal attempts, and total tackles. A multivariate canonical correlation analysis was then employed to verify the prediction of a multiple dependent variables set (composed of four technical actions) from an independent set of variables, composed of testosterone concentration, stage of pubic hair and genitalia development, vertical jumps and Yo-Yo performance. A moderate-to-large relationship between the technical performance set and the independent set was observed. The canonical correlation was 0.75 with a canonical R2 of 0.45. The highest structure coefficient in the technical performance set was observed for tackles (0.77), while testosterone presented the highest structure coefficient (0.75) for the variables of the independent set. The current data suggest that the selected independent set of variables might be useful in predicting SSG performance in young soccer players. Coaches should be aware that physical development plays a key role in technical performance to avoid decision-making mistakes during the selection of young players

Validation of a new method of placebo acupuncture with double-blind potential. Phase II : practitioner blinding

Se presenta un nuevo método de acupuntura placebo, evaluándose en esta fase el cegamiento del operador. Metodología: Se implementaron dos estudios experimentales utilizando como referencia el punto acupuntural Intestino Grueso 4 (IG4). En el primero (I) tres operadores utilizaron el dispositivo desarrollado en un mismo paciente. Mientras que en un segundo experimento (II), un único acupunturista utilizó dicho dispositivo en 12 voluntarios sanos. Resultados: En I, sobre un total de 30 agujas que utilizaron los operadores, estos pudieron identificar correctamente 7 (23%). Por otra parte, en el experimento II, los porcentajes de acierto encontrados no fueron significativamente diferentes de 50%, por lo cual no hay evidencia suficiente que permita decir que el acupunturista reconoce el tipo de aguja que está utilizando. Conclusiones: El nuevo dispositivo evidenció un alto potencial de cegamiento del operador, sugiriendo que es útil para enmascarar incluso a acupunturistas experimentados.We present a new placebo acupuncture method with potential for double¬ blinding. In this phase, we evaluate the possibility of blinding the practitioner. Methodology: We conducted two experimental studies using the acupuncture point of the Large Intestine 4 (LI4) as reference. In the first study (I), three practitioners used the device on the same patient. In the second experiment (II), a single acupuncturist used this device on 12 healthy volunteers. Results: In I, out of 30 needles used by the practitioners, they were able to correctly identify 7 needles (23%) (practitioner #1, 2/10; practitioner #2, 4/10; and practitioner #3, 1/10). In experiment II, success rates were around 50%, so there is not enough evidence to state that the acupuncturist recognizes the type of needle he is using. Conclusions: The new device showed high potential for practitioner blinding, suggesting that it is useful to blind even experienced acupuncturist

Centesimal Age and Relative Age Effect in Elite Futsal Players

International Journal of Exercise Science 13(6): 329-341, 2020. To investigate centesimal age (CA) and relative age effect (RAE) in elite male futsal players their date of birth and court-position were accessed through the official FIFA website. The absolute and relative frequency distributions of player births were quantified by quartiles and semesters. The two-way ANOVA and the Chi-Square analysis were applied to check for possible differences. The results showed a mean CA of 27.76 ± 4.11 years with no differences for both playing positions and competitions. In addition, no significant differences were found between quartiles or between semesters. The results suggest that elite male futsal athletes reach optimal competitive performance close to 27 years. Neither playing position nor geographical location may affect RAE, which seems to not affect the competitive performance (ranking) of elite male futsal players. These findings may help practitioners to understand the RAE phenomenon in futsal. In conclusion, being born in the early months of the year appears not to be important to successful performances in futsal. Overall, futsal athletes take about two decades to achieve their best performance. Coaches and researchers should consider the implementation of long-term training strategies (»20 years) to progressively and effectively develop young futsal players

Análises Univariadas e Multivariadas na classificação de atletas de voleibol masculino

O objetivo deste tudo foi comparar a utilização de análises univariadas e multivariadas e suas eventuais diferenças na elaboração de um coeficiente de classificação que possa auxiliar no processo de treinamento a longo prazo e na seleção e promoção de talentos na modalidade esportiva voleibol. A partir dos resultados de testes e medidas cineantropométricas selecionadas de acordo com a especificidade do voleibol, obtidas em uma amostra composta por atletas de voleibol masculino participantes das categorias mirim, infantil, infanto-juvenil, juvenil e principal, foram construídos três coeficientes de classificação: a) coeficiente de classificação por médias (CCM); b) coeficiente utilizando o escore padrão Z (CEZ); e c) coeficiente utilizando análise de componentes principais (CP), que foram comparados com a classificação subjetiva dos próprios treinadores (CT) dos atletas participantes do estudo. Os resultados demonstraram que as análises multivariadas, principalmente o CCM, parecem se ajustar ao que é observado na prática pelos treinadores, oferecendo boas perspectivas para a sua aplicação em estudos futuros. A análise de CEZ também apresentou resultados semelhantes mas, por não considerar as relações existentes entre as variáveis, é mais restrita tomando-se limitada para a complexidade que envolve os processos de seleção e promoção de talentosThe objective of this study is to compare univariate and multivariate analysis and its eventual differences in the elaboration of a classification coefficient that could help in the long term training process and in the promotion of talent in volleyball. From results of kinanthropometric tests and measures selected in accord with the specificity of volleyball, obtained from a sample composed by male volleyball athletes participating in young and adult categories, three classification coefficients were established: a) coefficient of classification by means (CCM); b) coefficient based on standard Z score (CEZ); c) coefficient based on principal components analysis (CP). They were compared with the subjective coaches classification (CT) of participating athletes. The results show that multivariate analysis, mainly the CCM, seems to adjust better the coaches impressions, offering good perspectives to its application to further studies. The CEZ analysis shows close results to CCM but, because is doesn’t consider the existence of interactions among the variables, it’s more restricted and therefore limited to the complexity that involves the procedures in talent selection and promotio

Prevalence of signs and symptoms of temporomandibular disorders in a young population at the beginning of treatment for drug dependence

Introducción: El consumo de drogas puede constituir un agente etiológico de trastornos témporomandibulares (TTM), lo cual debe ser tenido en cuenta al momento del diagnóstico y en la elaboración de un plan de tratamiento. Objetivo: Estimar la prevalencia de signos y síntomas de TTM en una población con dependencia a las drogas al inicio del régimen de internación y analizar posibles factores asociados. Material y método: Fue un estudio descriptivo y transversal, que incluyó pacientes consecutivos al inicio del tratamiento por consumo problemático de drogas. Participaron 135 pacientes internados en el Portal Amarillo y examinados por un investigador calibrado. Se solicitó consentimiento informado al participante y/o su representante legal. Resultados: la prevalencia de participantes con uno o más signos actuales de TTM fue de 29,7% y con uno o más síntomas actuales de TTM fue de 68,8%. La prevalencia de síntomas actuales de TTM presentó asociación significativa con autopercepción de estrés (p=.03), consumo de mate (p=.03) y de alcohol (p=.03). Conclusiones: La prevalencia de síntomas de TTM en una población en tratamiento por dependencia a las drogas es elevada respecto a la población general. Esto debe ser tenido en cuenta a la hora de desarrollar políticas de prevención y tratamiento.Introduction: Drug consumption may be an etiological agent of temporomandibular disorders (TMD) which should be considered when diagnosing a patient and developing a treatment plan. Objective: To estimate the prevalence of TMD signs and symptoms in a drug-dependent population at the beginning of their admission, and to analyze possible associated factors. Materials and methods: This was a descriptive cross-sectional study that included patients at the beginning of treatment for problematic drug use. We studied 135 subjects admitted to Portal Amarillo, Uruguay. The patients were examined by a calibrated researcher. Informed consent was requested from each participant and/or their legal representative. Results: The prevalence of subjects with one or more current TMD signs was 29.7%, and those with one or more current TMD symptoms accounted for 68.8%. The prevalence of current TMD symptoms showed a significant association with selfperceived stress (p=.03), mate consumption (p=.03) and alcohol consumption (p=.03). Conclusions: The prevalence of current TMD symptoms in the population under treatment for drug dependence is high compared to the general population. This should be considered when developing prevention and therapeutic strategies

Forecasting Rainfall Distribution Based on Deseasonalising Fuzzy Time Series Model

Rainfall prediction is an essential process to reduce loss of lives and properties. However, the accuracy of this prediction has been of many concerns in literature. Therefore, this paper proposed a model of rainfall prediction based on deseasonalising data and fuzzy time series concept. The historical data of rainfall distribution were collected from Drainage and Irrigation Department, Perlis Malaysia between January 2000 and December 2013. These data were analysed in order to determine the seasonal components using fuzzy time series as a medium. The study made use of deseasonalising rainfall data by employing fuzzy time series model in order to forecast the rainfall distribution. The model performance was evaluated by using statistical criteria of Mean Squared Error (MSE) and Root Mean Squared Error (RMSE). The obtained result was compared with several forecasting models in literature and it was found to be more accurate than others. Hence, this study demonstrates that fuzzy time series model is more suitable for the accurate prediction of rainfall distributions

Electron Dynamics in Films Made of Transition Metal Nanograins Embedded in SiO2:Infrared Reflectivity and Nanoplasma Infrared Resonance

We report on near normal infrared reflectivity spectra of ~550 nm thick films made of cosputtered transition metal nanograins and SiO2 in a wide range of metal fractions. Co0.85(SiO2)0.15,with conductivity well above the percolation threshold has a frequency and temperature behavior according to what it is find in conducting metal oxides. The electron scattering rate displays an unique relaxation time characteristic of single type of carriers experiencing strong electron-phonon interactions. Using small polaron fits we identify those phonons as glass vibrational modes. Ni0.61(SiO2)0.39, with a metal fraction closer to the percolation threshold, undergoes a metal-non metal transition at ~77 K. Here, as it is suggested by the scattering rate nearly quadratic dependence, we broadly identify two relaxation times (two carrier contributions) associated to a Drude mode and a mid-infrared overdamped band, respectively. Disorder induced, the mid-infrared contribution drives the phase transition by thermal electron localization. Co0.51(SiO2)0.49 has the reflectivity of an insulator with a distinctive band at ~1450cm\^{-1} originating in electron promotion, localization, and defect induced polaron formation. Angle dependent oblique reflectivity of globally insulating Co0.38(SiO2)0.62, Fe0.34(SiO2)0.66, and Ni0.28(SiO2)0.72, reveals a remarkable resonance at that band threshold. We understand this as due to the excitation by normal to the film electric fields of defect localized electrons in the metallic nanoparticle