1,231 research outputs found
The Journey After: A Phenomenological Examination of Teachers' Transfer of Learning from a Two-Year Professional Development Program.
Ph.D. Thesis. University of Hawaiʻi at Mānoa 2018
Influence of the number of trials and the exercise to rest ratio in repeated sprint ability, with changes of direction and orientation
The purpose of this
investigation was to determine if there were different trends in
physical fatigue observed in 3 different sets, of 7 trials each, in
repeated sprint training, performed in 3 different modes: straight
sprinting over 30 m, shuttle sprinting over 15 + 15 m, and sprinting
over 30 m with changes of direction. Recovery time among trials in the
sets was administered according to the 1:5 exercise to rest ratio. The
sets were performed on 3 different days, with at least 48 hours between
each set. The study involved 17 trained male soccer players (height,
177.33 +/- 6.21 cm; body mass, 71.63 +/- 9.58 kg; body mass index, 23
+/- 2.39 kg<bold>m(</bold>-2); age, 21.94 +/- 3.58 years). To compare
the different values of the time recorded, an index of fatigue was used.
Significant differences among trials within each set (repeated measures
analysis of variance; p < 0.05) and between the sets (factorial analysis
of variance; p < 0.001) were found. Significant correlations between
each test and countermovement jump and stiffness values recorded pre
exercise were found (p < 0.05). Significant differences between
countermovement jump and stiffness values recorded pre and post exercise
were also found (p < 0.05). This study suggests that training sessions
aimed at increasing the capacity of repeated sprint ability in nonlinear
and multidirectional sprints (shuttle and change of direction), which
might imply a different number of trials within the set or different
exercise to rest ratios from the ones usually adopted for straight
sprinting, to induce similar trends of fatigue. As practical
applications, the estimated numbers of necessary trials in the different
sets and the possible exercise to rest ratios, resulting from
mathematical modeling, are provided for each investigated sprinting
mode
Automatic alignment of surgical videos using kinematic data
Over the past one hundred years, the classic teaching methodology of "see
one, do one, teach one" has governed the surgical education systems worldwide.
With the advent of Operation Room 2.0, recording video, kinematic and many
other types of data during the surgery became an easy task, thus allowing
artificial intelligence systems to be deployed and used in surgical and medical
practice. Recently, surgical videos has been shown to provide a structure for
peer coaching enabling novice trainees to learn from experienced surgeons by
replaying those videos. However, the high inter-operator variability in
surgical gesture duration and execution renders learning from comparing novice
to expert surgical videos a very difficult task. In this paper, we propose a
novel technique to align multiple videos based on the alignment of their
corresponding kinematic multivariate time series data. By leveraging the
Dynamic Time Warping measure, our algorithm synchronizes a set of videos in
order to show the same gesture being performed at different speed. We believe
that the proposed approach is a valuable addition to the existing learning
tools for surgery.Comment: Accepted at AIME 201
Produção de mudas de abacaxi variedade BRS Imperial em função de tipos de seccionamento de talo.
A produção de mudas de qualidade fitossanitária de abacaxi é um grande gargalo para a expansão e crescimento da área produtiva desta cultura no país, principalmente para variedades novas. A propagação do abacaxizeiro se faz exclusivamente de forma vegetativa, ou seja, as mudas utilizadas no novo plantio são provenientes do cultivo anterior
Trends in ischemic heart disease and stroke death ratios in brazilian women and men
OBJECTIVE: Cardiovascular diseases are the main cause of death in women and men in Brazil, but the trends for the death ratios for ischemic heart disease and stroke in women and men remain unknown. METHOD: In this study, the trends for the death ratios among women and men who were over 30 years of age were analyzed from 1980 to 2005. Data were collected for both the Brazilian population and the metropolitan area of São Paulo. Estimates of the population size and data for mortality were then obtained from the Brazilian Institute of Geography and Statistics and the Ministry of Health. The risk for death was adjusted using a direct method. RESULTS: Death rates due to cardiovascular disease, ischemic heart disease, and stroke have declined in both Brazil and the metropolitan region of São Paulo. A linear regression analysis revealed a similar trend for ischemic heart disease and demonstrated a male/female ratio of 1.653 ± 0.001 (r=0.228; p=0.262) in Brazil and 1.763 ± 0.008 (r=0.863;
Antihyperon-Production in Relativistic Heavy Ion Collision
Recently it has been shown that the observed antiproton yield in heavy-ion
collisions at CERN-SpS energies can be understood by multi-pionic interactions
which enforce local chemical equilibrium of the antiprotons with the nucleons
and pions. Here we show that antihyperons are driven towards local chemical
equilibrium with pions, nucleons and kaons on a timescale of less than 3 fm/c
when applying a similar argument for the antihyperons by considering the
inverse channel of annihilation reactions anti-Y + p to pions + kaons. These
multi-mesonic reactions easily explain the antihyperon yields at CERN-SpS
energies as advertised in pure thermal, hadronic models without the need of a
quark gluon plasma phase. In addition, the argument also applies for AGS
energies.Comment: 4 pages using RevTeX, 1 eps figur
Exploring the interplay between metabolic power and equivalent distance in training games and official matches in soccer: a machine learning approach.
Introduction: This study aimed to explore the interplay between metabolic power (MP) and equivalent distance (ED) and their respective roles in training games (TGs) and official soccer matches. Furthermore, the secondary objective was to investigate the connection between external training load (ETL), determined by the interplay of metabolic power and equivalent distance, and internal training load (ITL) assessed through HR-based methods, serving as a measure of criterion validity. Methods: Twenty-one elite professional male soccer players participated in the study. Players were monitored during 11 months of full training and overall official matches. The study used a dataset of 4269 training games and 380 official matches split into training and test sets. In terms of machine learning methods, the study applied several techniques, including K-Nearest Neighbors, Decision Tree, Random Forest, and Support-Vector Machine classifiers. The dataset was divided into two subsets: a training set used for model training and a test set used for evaluation. Results: Based on metabolic power and equivalent distance, the study successfully employed four machine learning methods to accurately distinguish between the two types of soccer activities: TGs and official matches. The area under the curve (AUC) values ranged from 0.90 to 0.96, demonstrating high discriminatory power, with accuracy levels ranging from 0.89 to 0.98. Furthermore, the significant correlations observed between Edwards' training load (TL) and TL calculated from metabolic power metrics confirm the validity of these variables in assessing external training load in soccer. The correlation coefficients (r values) ranged from 0.59 to 0.87, all reaching statistical significance at p < 0.001. Discussion: These results underscore the critical importance of investigating the interaction between metabolic power and equivalent distance in soccer. While the overall intensity may appear similar between TGs and official matches, it is evident that underlying factors contributing to this intensity differ significantly. This highlights the necessity for more comprehensive analyses of the specific elements influencing physical effort during these activities. By addressing this fundamental aspect, this study contributes valuable insights to the field of sports science, aiding in the development of tailored training programs and strategies that can optimize player performance and reduce the risk of injuries in elite soccer
Acute effects of whole-body vibrations on the fatigue induced by multiple repeated sprint ability test in soccer players
Background: We tested the hypothesis that whole-body vibration (WBV) positively affects the fatigue process ensuing from repeated bouts of maximal efforts, as induced by repeated sprints' ability (RSA). Eleven male soccer players performed three sets of six repeated shuttle sprints (40 meters).
Methods: Eleven male soccer players (age 23.6±4.5 years) were cross-randomized to perform WBW before RSA and during the recovery between sets (WBV-with) or to warm-up and passive recovery between sets (WBV-without). The effects of WBV were quantified by sprint time (ST) and blood lactate concentration (LA), collected up to 15 min after completion of tests.
Results: ST during RSA showed a better maintenance of performance in the WBV-with compared to WBV-without condition in all three sets, reaching a statistical significance between-groups during the 2nd and 3rd set (P<0.05). No significant differences in ST over the sets were detected in WBV-with, whereas a significant decrease was observed in the WBV-without condition (P<0.001). LA recovered significantly faster from the 9th to 15th minute of recovery in WBV-with as compared to WBV-without (P<0.05).
Conclusions: These findings would indicate that WBV performed during recovery between RSA sets can delay the onset of muscle fatigue resulting in a better maintenance of sprint performance
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