RESUMO
Amorphous microwires have attracted substantial attention in the past decade because of their useful technological applications. Their bistable magnetic response is determined by positive or negative magnetostriction, respectively. First-order reversal curves (FORC) are a powerful tool for analyzing the magnetization reversal processes of many-body ferromagnetic systems that are essential for a deeper understanding of those applications. After theoretical considerations about magnetostatic interactions among microwires, this work introduces a systematic experimental study and analysis of the FORC diagrams for magnetostrictive microwires exhibiting an individually bistable hysteresis loop, from a single microwire to sets of an increasing number of coupled microwires, the latter considered as an intermediate case to the standard many-body problem. We performed the study for sets of quasi-identical and different hysteretic microwires where we obtained the coercivity Hc and interaction Hu fields. In the cases with relevant magnetostatic interactions, FORC analysis supplies deeper information than standard hysteresis loops since the intrinsic fluctuations of the switching field generate a complex response. For sets of microwires with very different coercivity, the coercivity distributions of the individual microwires characterize the FORC diagram.
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The market for wrist-worn devices is growing at previously unheard-of speeds. A consequence of their fast commercialization is a lack of adequate studies testing their accuracy on varied populations and pursuits. To provide an understanding of wearable sensors for sports medicine, the present study examined heart rate (HR) measurements of four popular wrist-worn devices, the (Fitbit Charge (FB), Apple Watch (AW), Tomtom runner Cardio (TT), and Samsung G2 (G2)), and compared them with gold standard measurements derived by continuous electrocardiogram examination (ECG). Eight athletes participated in a comparative study undergoing maximal stress testing on a cycle ergometer or a treadmill. We analyzed 1,286 simultaneous HR data pairs between the tested devices and the ECG. The four devices were reasonably accurate at the lowest activity level. However, at higher levels of exercise intensity the FB and G2 tended to underestimate HR values during intense physical effort, while the TT and AW devices were fairly reliable. Our results suggest that HR estimations should be considered cautiously at specific intensities. Indeed, an effective intervention is required to register accurate HR readings at high-intensity levels (above 150 bpm). It is important to consider that even though none of these devices are certified or sold as medical or safety devices, researchers must nonetheless evaluate wrist-worn wearable technology in order to fully understand how HR affects psychological and physical health, especially under conditions of more intense exercise.
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The myths surrounding women's participation in sport have been reflected in respiratory physiology. This study aims to demonstrate that continuous monitoring of blood oxygen saturation during a maximal exercise test in female athletes is highly correlated with the determination of the second ventilatory threshold (VT2) or anaerobic threshold (AnT). The measurements were performed using a pulse oximeter during a maximum effort test on a treadmill on a population of 27 healthy female athletes. A common behavior of the oxygen saturation evolution during the incremental exercise test characterized by a decrease in saturation before the aerobic threshold (AeT) followed by a second significant drop was observed. Decreases in peripheral oxygen saturation during physical exertion have been related to the athlete's physical fitness condition. However, this drop should not be a limiting factor in women's physical performance. We found statistically significant correlations between the maximum oxygen uptake and the appearance of the ventilatory thresholds (VT1 and VT2), the desaturation time, the total test time, and between the desaturation time and the VT2. We observed a relationship between the desaturation time and the VT2 appearance. Indeed, a linear regression model between the desaturation time and the VT2 appearance can predict 80% of the values in our sample. Besides, we suggest that pulse oximetry is a simple, fairly accurate, and non-invasive technique for studying the physical condition of athletes who perform physical exertion.
Assuntos
Oximetria , Consumo de Oxigênio , Saturação de Oxigênio , Atletas , Feminino , Humanos , OxigênioRESUMO
Resumen: Introducción: Evaluar el conocimiento (saber) sobre primeros auxilios (PA) en estudiantes de la carrera Profesor de Educación Física de la Universidad de Tarapacá, comparando el centro de estudios de procedencia y el género del alumnado. Metodología: Se efectuó un estudio mixto, con variables cualitativas y cuantitativas, en el que se indagó sobre el conocimiento en primeros auxilios en estudiantes de la carrera Profesor de Educación Física de la Universidad de Tarapacá. Se evaluó a 169 estudiantes, 99 con ingresos procedentes del Centro de Formación Técnica Tarapacá y 70 con incorporación a partir de la Prueba de Selección Universitaria. Se aplicó una encuesta, validada por criterio experto, que investigó sobre el conocimiento (saber) en relación con primeros auxilios. Se utilizó un pretest y, posteriormente, se intervino con un curso formativo teórico-práctico en primeros auxilios. Al finalizar el curso, se efectuó un postest, que tuvo como finalidad comprobar los conocimientos adquiridos sobre primeros auxilios. Resultados: Se observó que los hombres mostraron mayor conocimiento durante el pretest y el postest, con un 95.1 % y un 100 %, respectivamente, mientras que las mujeres registraron un 75 % en el pretest y 90.1 % en el postest. Por otro lado, el alumnado procedente del Centro de Formación Técnica mantuvo indicadores superiores en ambos análisis. Conclusiones: Los conocimientos adquiridos en enseñanza intermedia, así como la realización de cursos iniciales relacionados con primeros auxilios, favorecen la preparación del futuro profesorado de educación física, lo que conlleva un mejor accionar ante situaciones de emergencia, tanto en las escuelas como en la vida cotidiana.
Abstract: Introduction: To evaluate the knowledge (knowledge) about first aid (PA) in students of the Physical Education Professor career at the University of Tarapacá, comparing the study center of origin and the gender of the students. Methodology: A mixed study was carried out, with qualitative and quantitative variables, inquiring about knowledge in first aid in students of the Physical Education Professor Career, University of Tarapacá. 169 students were evaluated, 99 with income from the Tarapacá Technical Training Center and 70 incorporated from the University Selection Test. A survey was applied, validated by expert criteria, inquiring about knowledge (knowledge) in relation to first aid. A pre-test was used and subsequently a theoretical-practical training course in first aid was intervened. At the end of the course, a post-test was carried out, which the purpose of verifying the knowledge had acquired about first aid. Results: It was observed that the men showed greater knowledge during the pre-test and the post-test, with 95.1% and 100% respectively, while the women showed 75% in the pre-test and 90.1% in the post-test. On the other hand, students from the Technical Training Center maintained higher indicators in both analyses. Conclusions: The knowledge acquired in intermediate education, as well as the completion of initial courses related to first aid, favor the preparation of future Physical Education teachers, which leads to better actions in emergency situations, both in schools and in life everyday.
Resumo: Introdução: Avaliar o conhecimento sobre primeiros socorros (PS) dos estudantes da carreira de Professor de Educação Física da Universidade de Tarapacá, Chile, comparando o centro de estudos de origem e o gênero dos estudantes. Metodologia: Foi realizado um estudo misto, com variáveis qualitativas e quantitativas, no qual foram investigados conhecimentos sobre primeiros socorros em estudantes da carreira de Professor de Educação Física da Universidade de Tarapacá. O estudo avaliou 169 alunos, 99 provenientes do Centro de Treinamento Técnico de Tarapacá, e 70 que passaram no exame de admissão. Foi realizada uma pesquisa validada por especialistas, perguntando sobre os conhecimentos em relação aos primeiros socorros. Um pré-teste foi aplicado e, posteriormente, um curso teórico-prático de treinamento em primeiros socorros foi ministrado. Ao final do curso, foi realizado um pós-teste com o objetivo de verificar os conhecimentos adquiridos nos primeiros socorros. Resultados: Foi observado que os homens mostraram maiores conhecimentos durante o pré-teste e o pós-teste, com 95,1% e 100% respectivamente, enquanto as mulheres mostraram 75% no pré-teste e 90,1% no pós-teste. Por outro lado, os estudantes do Centro de Treinamento Técnico mantiveram indicadores mais elevados em ambas as análises. Conclusões: Os conhecimentos adquiridos no ensino médio, assim como a conclusão dos cursos iniciais de primeiros socorros, favorecem a preparação dos futuros professores de Educação Física, o que leva a melhores ações em situações de emergência, tanto nas escolas como na vida cotidiana.