The Effects of Athletic Participation on Self-Concept, Daily School Attendance, and Grade Point Average of Female Seventh-Grade Students in Urban Schools

This study examined the effects of athletic participation on self-concept, daily school attendance, and grade point average on 503 seventh grade students in urban middle schools. A 2 x 3 factorial MANOVA analyzed self-concept data to determine differences in self-concept associated with the levels of athletic participation with that of pre- and post-treatment test periods. Tukey\u27s post hoc tests were incorporated when a significant F ratio was demonstrated (p\u3c 0.05). Significant differences were noted in four areas of self-concept as defined by Piers-Harris (1984): (1) intellectual and school status (Tukey, p\u3c 0.05), (2) physical appearance and attributes (Tukey, p\u3c 0.05), (3) anxiety (Tukey, p\u3c 0.05), and (4) popularity (Tukey, p\u3c 0.05). No significant differences were noted in three areas of self-concept: (1) behavior, (2) happiness and satisfaction, and (3) self-concept total. A 3 x 3 factorial ANOVA demonstrated statistical differences in daily school attendance between female students participating in interscholastic athletics with female students not participating in interscholastic athletics. Daily school attendance reports were collected to coincide with three grading periods. Tukey\u27s post hoc tests were incorporated when a significant F ratio was demonstrated (Tukey, p\u3c 0.05). Students not participating in interscholastic athletics noted higher absenteeism than students who participated in interscholastic athletics (Tukey, p\u3c 0.05). A 3 x 3 factorial ANOVA demonstrated statistical differences in grade point averages between female students participating in interscholastic athletics with those female students not participating in interscholastic athletics. Grade point averages of the two-sport participants were significantly higher than the one-sport participants (Tukey, p\u3c 0.05). Grade point averages of the one-sport participants were significantly higher than the no-sport participants (Tukey, p\u3c 0.05). Results suggest positive effects of athletic participation on self-concept, daily school attendance, and grade point average of female seventh grade students in urban middle schools participating in interscholastic sports programs

Effect of Brief Biofeedback via a Smartphone App on Stress Recovery: Randomized Experimental Study.

BACKGROUND:Smartphones are often vilified for negatively influencing well-being and contributing to stress. However, these devices may, in fact, be useful in times of stress and, in particular, aid in stress recovery. Mobile apps that deliver evidence-based techniques for stress reduction, such as heart rate variability biofeedback (HRVB) training, hold promise as convenient, accessible, and effective stress-reducing tools. Numerous mobile health apps that may potentially aid in stress recovery are available, but very few have demonstrated that they can influence health-related physiological stress parameters (eg, salivary biomarkers of stress). The ability to recover swiftly from stress and reduce physiological arousal is particularly important for long-term health, and thus, it is imperative that evidence is provided to demonstrate the effectiveness of stress-reducing mobile health apps in this context. OBJECTIVE:The purpose of this research was to investigate the physiological and psychological effects of using a smartphone app for HRVB training following a stressful experience. The efficacy of the gamified Breather component of the Happify mobile health app was examined in an experimental setting. METHODS:In this study, participants (N=140) underwent a laboratory stressor and were randomly assigned to recover in one of three ways: with no phone present, with a phone present, with the HRBV game. Those in the no phone condition had no access to their phone. Those in the phone present condition had their phone but did not use it. Those in the HRVB game condition used the serious game Breather on the Happify app. Stress recovery was assessed via repeated measures of salivary alpha amylase, cortisol, and self-reported acute stress (on a 1-100 scale). RESULTS:Participants in the HRVB game condition had significantly lower levels of salivary alpha amylase during recovery than participants in the other conditions (F2,133=3.78, P=.03). There were no significant differences among the conditions during recovery for salivary cortisol levels or self-reported stress. CONCLUSIONS:These results show that engaging in a brief HRVB training session on a smartphone reduces levels of salivary alpha amylase following a stressful experience, providing preliminary evidence for the effectiveness of Breather in improving physiological stress recovery. Given the known ties between stress recovery and future well-being, this study provides a possible mechanism by which gamified biofeedback apps may lead to better health

Towards the understanding of the molecular weight dependence of essential work of fracture in semi-crystalline polymers: A study on poly(ε-caprolactone)

The plane-stress ductile fracture of poly(#-caprolactone) (PCL) has been investigated as a function of molecular weight and related crystalline structure. Because of the interacting effects in semi-crystalline polymers a separate study of a given structural parameter is rather challenging. Nevertheless, this polymer seems to be a good model material to study the effect of molecular weight on the essential work of fracture, as the interactions between the separate parameters, at room temperature, are negligible. The molecular characteristics of PCL were determined by size exclusion chromatography. To confirm the entangled molecular structure of studied polymers rheological measurements were performed. The crystalline morphology has been characterized by differential scanning calorimetry and wide angle X-ray diffraction. Quasi-static tensile tests and essential work of fracture tests were performed to study the mechanical behavior. Based on the experimental observations an empirical model has been proposed to outline the molecular weight and crystallinity dependence of the essential work of fracture in this semi-crystalline polymer

Molecular Spiders in One Dimension

Molecular spiders are synthetic bio-molecular systems which have "legs" made of short single-stranded segments of DNA. Spiders move on a surface covered with single-stranded DNA segments complementary to legs. Different mappings are established between various models of spiders and simple exclusion processes. For spiders with simple gait and varying number of legs we compute the diffusion coefficient; when the hopping is biased we also compute their velocity.Comment: 14 pages, 2 figure

Bayesian approach to cyclic activity of CF Oct

Bayesian statistical methods of Gregory-Loredo and the Bretthorst generalization of the Lomb-Scargle periodogram have been applied for studying activity cycles of the early K-type subgiant star CF Oct. We have used a ~45 year long dataset derived from archival photographic observations, published photoelectric photometry, Hipparcos data series and All Sky Automated Survey archive. We have confirmed the already known rotational period for the star of 20.16 d and have shown evidences that it has exhibited changes from 19.90 d to 20.45 d. This is an indication for stellar surface differential rotation.The Bayesian magnitude and time--residual analysis reveals clearly at least one long-term cycle. The cycle lenght's posterior distributions appear to be multimodal with a pronounced peak at a period of 7.1 y with FWHM of 54 d for time-residuals and at a period of 9.8 y with FWHM of 184 d for magitude data. These results are consistent with the previously postulated cycle of 9+/-3 years.Comment: The paper contains 6 figures and 3 tables. Accepted for publication in Monthly Notices of the Royal Astronomical Society Main Journa

A star under multiple influences. Magnetic activity in V815 Her, a compact 2+2 hierarchical system

We are conducting a comprehensive investigation of V815 Her using photometric and spectroscopic data to understand the origin of the activity and what influences it in the short and long term. Using TESS photometry we performed light curve modeling in order to derive astrophysical and orbital parameters for the eclipsing binary subsystem V815 Her B. Using archival photometric data covering a century we carried out a time frequency analysis. Spectral synthesis was applied to determine the basic astrophysical parameters of the rapidly rotating primary using high-resolution STELLA spectra recorded in 2018. Photometric analysis revealed multiple cycles on timescales between ~6.5 and ~26 years. From TESS photometry we obtained orbital solution for the V815 Her B subsystem. The STELLA spectra covering the 200 day-long observing season enabled to create 19 time-series Doppler images, which revealed a constantly changing spotted surface. From the consecutive image pairs we measured a weak solar-type surface differential rotation of the spotted star. We found evidence that the V815 Her B component previously apostrophized as a third body is actually an eclipsing close binary subsystem of two M dwarfs with a period of 0.5 d, i.e., V815 Her is a 2+2 hierarchical quadruple system. The system is apparently young, only a few times ten million years old, consistent with the spotted primary V815 Her Aa being a zero-age main sequence star. Spot activity on the primary was found to be vivid. Fast starspot decay suggests that convective-turbulent erosion plays a more significant role in such a rapidly rotating star. The weak differential rotation of V815 Her Aa is presumably confined by tidal forces of the close companion V815 Her Ab. The slowly increasing photometric cycle of 6.5 years on average is interpreted as a spot cycle of V815 Her Aa, which is probably modulated by the eccentric wide orbit.Comment: 26 pages, to be published in Astronomy and Astrophysics (after final revision