1,652 research outputs found

    Efecto de la probabilidad de errores durante la acción de ataque de esgrima

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    El propósito de este estudio ha sido comprobar el efecto que tiene la probabilidad de que surja el error durante la realización de una acción de ataque en esgrima, sobre los parámetros temporales de las respuestas de reacción (TRR) y la velocidad de desplazamiento del centro de masas (CM). Han participado 17 esgrimistas (14 hombres y 3 mujeres), con una experiencia en competición regional de más de cinco años. Para el registro de los datos, se han utilizado dos plataformas de fuerza, operando a 500 Hz, una cámara de vídeo, a 210 Hz y un cronómetro electrónico adaptado al sistema de cableado de las armas. Una señal electrónica se utilizó para sincronizar temporalmente todos los registros. Para la situación experimental donde no existía incertidumbre durante la acción (CIA), los esgrimistas tenían que realizar un ataque simple con fondo lo más rápidamente posible al aparecer un círculo en el centro del plastrón (E1), intentando situar la punta de la espada dentro del círculo. Para la situación experimental donde existía incertidumbre debida a la posibilidad de error (CIA), los esgrimistas tenían los mismos objetivos que en la situación anterior, aunque debían de inhibir la acción de ataque a otra de defensiva, en el caso de que el círculo desapareciera del plastrón durante la acción. Los resultados ponen de manifiesto que, cuando existe la posibilidad de error durante la realización del ataque en esgrima, se incrementan los parámetros temporales de la respuesta de reacción (TR y TM) y disminuye la velocidad de ejecución.The main aim of this study has been to verify the effect that has the probability from which the mistake arises during the accomplishment of an action of assault in fencing, on the temporary parameters of the answers of reaction (TRR) and the speed of displacement of the center of masses (CM). 17 fencers (14 men and 3 women), with an experience in regional competition of more than five years took part in this study. Two force platforms, operating to 500 Hz have been in used, a video camera, to 210 Hz and an electronic chronometer adapted to the system of wired up of the weapon for the record of the data. An electronic sign was used for synchronizing temporarily all the records. For the experimental situation where uncertainty did not exist during the action (CIA), the fencers had to realize a simple assault with lunge as rapidly as possible when a circle appeared in the center of the plastron (E1), trying to place the top of the sword inside the circle. For the experimental situation where there existed uncertainty due to the possibility of mistake (CIA), the fencers had the same aims that in the previous situation, though they must disable the action of assault to other one of defensive, in case the circle was disappearing of the plastron during the action. The results reveal that, when the possibility of mistake exists during the accomplishment of the assault in fencing, there are increased the temporary parameters of the response of reaction (TR and TM) and it diminishes the speed of execution.Peer Reviewe

    Efecto de la probabilidad de errores durante la acción de ataque de esgrima

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    El propósito de este estudio ha sido comprobar el efecto que tiene la probabilidad de que surja el error durante la realización de una acción de ataque en esgrima, sobre los parámetros temporales de las respuestas de reacción (TRR) y la velocidad de desplazamiento del centro de masas (CM). Han participado 17 esgrimistas (14 hombres y 3 mujeres), con una experiencia en competición regional de más de cinco años. Para el registro de los datos, se han utilizado dos plataformas de fuerza, operando a 500 Hz, una cámara de vídeo, a 210 Hz y un cronómetro electrónico adaptado al sistema de cableado de las armas. Una señal electrónica se utilizó para sincronizar temporalmente todos los registros. Para la situación experimental donde no existía incertidumbre durante la acción (CIA), los esgrimistas tenían que realizar un ataque simple con fondo lo más rápidamente posible al aparecer un círculo en el centro del plastrón (E1), intentando situar la punta de la espada dentro del círculo. Para la situación experimental donde existía incertidumbre debida a la posibilidad de error (CIA), los esgrimistas tenían los mismos objetivos que en la situación anterior, aunque debían de inhibir la acción de ataque a otra de defensiva, en el caso de que el círculo desapareciera del plastrón durante la acción. Los resultados ponen de manifiesto que, cuando existe la posibilidad de error durante la realización del ataque en esgrima, se incrementan los parámetros temporales de la respuesta de reacción (TR y TM) y disminuye la velocidad de ejecución.The main aim of this study has been to verify the effect that has the probability from which the mistake arises during the accomplishment of an action of assault in fencing, on the temporary parameters of the answers of reaction (TRR) and the speed of displacement of the center of masses (CM). 17 fencers (14 men and 3 women), with an experience in regional competition of more than five years took part in this study. Two force platforms, operating to 500 Hz have been in used, a video camera, to 210 Hz and an electronic chronometer adapted to the system of wired up of the weapon for the record of the data. An electronic sign was used for synchronizing temporarily all the records. For the experimental situation where uncertainty did not exist during the action (CIA), the fencers had to realize a simple assault with lunge as rapidly as possible when a circle appeared in the center of the plastron (E1), trying to place the top of the sword inside the circle. For the experimental situation where there existed uncertainty due to the possibility of mistake (CIA), the fencers had the same aims that in the previous situation, though they must disable the action of assault to other one of defensive, in case the circle was disappearing of the plastron during the action. The results reveal that, when the possibility of mistake exists during the accomplishment of the assault in fencing, there are increased the temporary parameters of the response of reaction (TR and TM) and it diminishes the speed of execution.Peer Reviewe

    Effectiveness of a Multifactorial Intervention in the First 1000 Days of Life to Prevent Obesity and Overweight in Childhood: Study Protoco

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    (1) Background: Obesity is a global health problem, and its prevention must be a priority goal of public health, especially considering the seriousness of the problem among children. It is known that fetal and early postnatal environments may favor the appearance of obesity in later life. In recent years, the impact of the programs to prevent obesity in childhood has been scarce. The aim of this research is to evaluate the effectiveness of an intervention based on the concept of early programming. (2) Methods: Non-randomized controlled trial design. Inclusion criteria are: two-year-old infants whose gestational period begins in the 14 months following the start of the intervention, and whose mothers have made the complete follow-up of their pregnancy in the same clinical unit of the study. The intervention will be developed over all the known factors that affect early programming, during pregnancy up to 2 years of life. Data will be collected through a data collection sheet by the paediatricians. A unibivariate and multivariate analysis of the data will be carried out. (3) Ethics and dissemination: The trial does not involve any risk to participants and their offspring. Signed informed consent is obtained from all participants. Ethical approval has been obtained. (4) Results: It is expected that this study will provide evidence on the importance of the prevention of obesity from the critical period of the first 1000 days of life, being able to establish this as a standard intervention in primary care

    Propiedades de las rocas volcánicas de Canarias (España) utilizadas como material de escollera

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    In the Canary Islands, there is a wide spectrum of volcanic rocks with different properties to be used in public works. The aim of this study is to analyse the physical-mechanical properties of all the volcanic rocks present in the Canary Island archipelago in order to determine their suitability for use in maritime construction works. The great variety of volcanic rocks present on the islands have been grouped into lithotypes based on similar geo-mechanical behaviour. The laboratory test results obtained for these lithotypes establish their suitability or not to be used as breakwater material in accordance with Spanish regulations.En el archipiélago canario existe un amplio espectro de rocas volcánicas con diferentes propiedades para ser utilizadas en obras públicas. El objetivo de este estudio es analizar las propiedades físico-mecánicas de todas las rocas volcánicas presentes en el archipiélago canario con el fin de determinar su idoneidad para ser utilizadas en obras de construcción marítima. La gran variedad de rocas volcánicas presentes en las islas, se han agrupado en litotipos basados en un comportamiento geomecánico similar. Los resultados de los ensayos de laboratorio obtenidos para estos litotipos establecen su idoneidad o no para ser utilizados como material de escollera de acuerdo con la normativa española

    Metrics to guide a multi-objective evolutionary algorithm for ordinal classification

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    Ordinal classification or ordinal regression is a classification problem in which the labels have an ordered arrangement between them. Due to this order, alternative performance evaluation metrics are need to be used in order to consider the magnitude of errors. This paper presents a study of the use of a multi-objective optimization approach in the context of ordinal classification. We contribute a study of ordinal classification performance metrics, and propose a new performance metric, the maximum mean absolute error (MMAE). MMAE considers per-class distribution of patterns and the magnitude of the errors, both issues being crucial for ordinal regression problems. In addition, we empirically show that some of the performance metrics are competitive objectives, which justify the use of multi-objective optimization strategies. In our case, a multi-objective evolutionary algorithm optimizes an artificial neural network ordinal model with different pairs of metric combinations, and we conclude that the pair of the mean absolute error (MAE) and the proposed MMAE is the most favourable. A study of the relationship between the metrics of this proposal is performed, and the graphical representation in the two-dimensional space where the search of the evolutionary algorithm takes place is analysed. The results obtained show a good classification performance, opening new lines of research in the evaluation and model selection of ordinal classifiers

    Saliva secretory IgA kinetics in obese subjects submitted to a graded exercise test

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    INTRODUCTION: Secretory IgA (sIgA) is predominant immunoglobulin in secretions of the mucosal immune system. It inhibit attachment and replication of pathogenic microorganism, preventing colonization by these pathogens. Therefore, sIgA is consider the first line of defense against pathogens. Previous studies have indicated a direct link between low salivary sIgA levels with of upper respiratory tract infections (UTRI) episodes in endurance sports and elite athletes. PURPOSE: Determine the effect of a maximal graded exercise test on the saliva sIgA levels in obese adult subjects. METHODS: Eleven obese male subjects (Age 31± 1.53 years) were recruited. The Body Mass Index (BMI) and, Waist Circumference (WC) were measured. Graded exercise test was performed on an electrically-braked cycle ergometer (Lode). The Heart rate (HR) was registered using a digital pulse meter (Polar FT1 model) before, immediately finished the exercise and after 30 min post- exercise test. The saliva samples were collected alongside with HR during the test. RESULTS: The WC (110.37 ± 3.89 cm) and BMI (34.73 ± 1.62 kg/m2) values confirmed the obesity state in the participants. The HR at basal was 77.09 ± 3.10 bpm, at post exercise, the HR mean was 175.45 ± 4.94 bpm (p \u3c0.0001 vs basal). Finally, at 30 post exe, the HR was 91.81 ± 3.01 bpm (P \u3c0.0001 vs post-exe). In basal state, the sIgA concentration was 94.21 ± 13.57 µm/mL. At post exe, the sIgA mean was 175.9 ± 22.45 µm/mL (p\u3c0.05 vs basal). Finally, 30’ post-exercise the sIgA level was 91.39 ± 10.40 µm/mL. However, the sIgA was not modified by the exercise. CONCLUSION: The present work demonstrates that the salivary sIgA increases temporally as a response to the graded exercise test in obese adults. Although, the changes in the sIgA concentration was not accompanied with a major sIgA secretion in the saliva
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