Optimal sampling frequency in recording of resistance training exercises     

Paolo Bardella  Irene Carrasquilla García  Marco Pozzo  Julio Tous-Fajardo  Eduardo Saez de Villareal 《Sports biomechanics / International Society of Biomechanics in Sports》2017,16(1):102-114

The purpose of this study was to analyse the raw lifting speed collected during four different resistance training exercises to assess the optimal sampling frequency. Eight physically active participants performed sets of Squat Jumps, Countermovement Jumps, Squats and Bench Presses at a maximal lifting speed. A linear encoder was used to measure the instantaneous speed at a 200 Hz sampling rate. Subsequently, the power spectrum of the signal was computed by evaluating its Discrete Fourier Transform. The sampling frequency needed to reconstruct the signals with an error of less than 0.1% was f_99.9 = 11.615 ± 2.680 Hz for the exercise exhibiting the largest bandwidth, with the absolute highest individual value being 17.467 Hz. There was no difference between sets in any of the exercises. Using the closest integer sampling frequency value (25 Hz) yielded a reconstruction of the signal up to 99.975 ± 0.025% of its total in the worst case. In conclusion, a sampling rate of 25 Hz or above is more than adequate to record raw speed data and compute power during resistance training exercises, even under the most extreme circumstances during explosive exercises. Higher sampling frequencies provide no increase in the recording precision and may instead have adverse effects on the overall data quality.  相似文献   

Perceived health problems in swimmers according to the chemical treatment of water in swimming pools     

Álvaro Fernández-Luna  Pablo Burillo  José Luis Felipe  Julio del Corral  Jorge García-Unanue  Leonor Gallardo 《European Journal of Sport Science》2016,16(2):256-265

The objective of this study was to determine which chemical treatment used for disinfecting water in indoor swimming pools had the least impact on users' perceptions of health problems, and which generated the greatest satisfaction with the quality of the water. A survey on satisfaction and perceived health problems was given to 1001 users at 20 indoor swimming pools which used different water treatment methods [chlorine, bromine, ozone, ultraviolet lamps (UV) and salt electrolysis]. The findings suggest that there is a greater probability of perceived health problems, such as eye and skin irritation, respiratory problems and skin dryness, in swimming pools treated with chlorine than in swimming pools using other chemical treatment methods. Pools treated with bromine have similar, although slightly better, results. Other factors, such as age, gender, time of day of use (morning and afternoon) and type of user (competitive and recreational), can also affect the probability of suffering health problems. For all of the above, using combined treatment methods as ozone and UV, or salt electrolysis produces a lower probability of perceived health problems and greater satisfaction.  相似文献   

Editorial     

Julio Grao  & José-Giné Mora 《European Journal of Education》2000,35(1):1-5

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Light-load maximal lifting velocity full squat training program improves important physical and skill characteristics in futsal players     

Julio Torres-Torrelo  Juan José González-Badillo 《Journal of sports sciences》2017,35(10):967-975

This study aimed to compare the effect of 6 weeks of resistance training or combined resistance training and change of direction exercises on physical performance and motor skills in futsal players. Thirty-four futsal players were divided into full squat group (SG, n = 12), combined full squat and change of direction exercises group (S+CDG, n = 12) and control group (CG, n = 10). The resistance training for SG consisted of full squat with low load (~45–58% 1RM) and low volume (4–6 repetitions), whereas the S+CDG performed the same resistance training program combined with loaded change of direction. Sprint time in 10 and 20 m, change of direction test, countermovement vertical jump (CMJ) height, maximal strength and force–velocity relationship in full squat exercise, kicking speed ball (BS_mean) and repeated sprint ability (RSA_mean) were selected as testing variables. Both experimental groups showed significant improvements for CMJ, BS_mean and all strength parameters. Only SG resulted in significant sprint gains, whereas S+CDG also achieved significant improvements in RSA_mean. The CG remained unchanged after training period. No significant differences were found between both experimental groups. These findings suggest that only 12 sessions of either lightweight resistance training alone, lifting the load at maximal intended velocity or combined with change of direction exercises is enough to improve several physical and skills capacities critical to futsal performance in adult players.  相似文献   

A survey on the light-fastness properties of organic-based Alaska Native artifacts     

Julio M. del Hoyo-Melndez  Marion F. Mecklenburg 《Journal of Cultural Heritage》2010,11(4):48-499

A series of light-fastness tests were conducted on a group of ethnographic objects that will be on exhibit at the Smithsonian Institution Arctic Studies Center, a recent addition to the Anchorage Museum at Rasmuson Center in Alaska. The objects surveyed belong to the collections of the Smithsonian National Museum of Natural History and the Smithsonian National Museum of the American Indian. This work was designed as a feasibility study on the use of a micro-fading tester as a non-contact and non-destructive technique to evaluate the light-stability of materials present in ethnographic collections. A broad range of objects containing a wide variety of materials were selected for the study. The materials investigated included a variety of dyes applied on silk, cotton, and wool substrates along with some unusual materials such as tanned skin and seal gut skin. The results from this investigation have allowed establishing exhibition recommendations taking into consideration the sensitivity of each object, light levels in the museum building, and estimated light exposures based on the duration of the exhibit. The micro-fading tester has proven to be a very useful tool for determining the light-stability of ethnographic materials without causing any harm to the objects. Objects containing equivalent materials are usually classified under a general category based on their probable sensitivity to light. However, micro-fading test results have permitted the detection of dissimilarities among some of these objects, which could be associated to variations in prior fading histories, the quality of raw materials, and different preparation methods.  相似文献   

Red pigment production by Penicillium purpurogenum GH2 is influenced by pH and temperature     

Méndez A  Pérez C  Montañéz JC  Martínez G  Aguilar CN 《Journal of Zhejiang University. Science. B》2011,12(12):961-968

The combined effects of pH and temperature on red pigment production and fungal morphology were evaluated in a submerged culture of Penicillium purpurogenum GH2, using Czapek-Dox media with d-xylose as a carbon source. An experimental design with a factorial fix was used: three pH values (5, 7, and 9) and two temperature levels (24 and 34 °C) were evaluated. The highest production of red pigment (2.46 g/L) was reached with a pH value of 5 and a temperature of 24 °C. Biomass and red pigment production were not directly associated. This study demonstrates that P. purpurogenum GH2 produces a pigment of potential interest to the food industry. It also shows the feasibility of producing and obtaining natural water-soluble pigments for potential use in food industries. A strong combined effect (p<0.05) of pH and temperature was associated with maximal red pigment production (2.46 g/L).  相似文献   

Editorial     

Julio González Bello 《International Journal for Educational and Vocational Guidance》2015,15(3):191-192

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The world of work between the personal and the collective: a demand for social justice and guidance for Latin America     

Julio Gonzalez Bello  Omaira Chacón 《International Journal for Educational and Vocational Guidance》2015,15(3):237-246

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The academic writing process in Spanish universities: perceptions of students and faculty / El proceso de escritura académica en la universidad española: percepciones de estudiantes y profesores     

Javier Marín  Sonia López  Julio Roca-De-Larios 《Cultura y Educación》2015,27(3):504-533

Abstract

This paper is intended as an exploration of university faculty and students’ perceptions of a number of dimensions involved in the written composition of academic texts. We analysed the responses to scale 3 in the European Writing Survey (EUWRIT) (in its Spanish version: Encuesta Europea sobre la Escritura Académica, EEEA) by a group of social science and humanities students (n = 1,030) and faculty (n = 230) from nine Spanish universities. We then examined the similarities and differences in their perceptions and established a factorial structure of the different dimensions underlying the writing process. The data indicate that both groups concur in the value assigned to both changing ideas in the course of the composition process (although this process seems to be understood differently by each group) and the revision and feedback processes. The students, however, claim to be involved in more planning and previous reading activities than the teachers perceive them to be. The significance of these results for a process-oriented perspective in academic writing is discussed.  相似文献   

Teachers' digital competence to assist students with functional diversity: Identification of factors through logistic regression methods     

Julio Cabero-Almenara  Francisco D. Guillén-Gámez  Julio Ruiz-Palmero  Antonio Palacios-Rodríguez 《British journal of educational technology : journal of the Council for Educational Technology》2022,53(1):41-57

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