SALIVARY BIOMARKER ASSESSMENT OF ELITE COLLEGIATE BASKETBALL PLAYERS ACROSS AN NCAA SEASON

The ratio between testosterone and cortisol (TC) has been used to monitor training stress and performance in athletes. PURPOSE: To monitor free testosterone (T), cortisol (C), and the ratio of testosterone to cortisol (TC) in elite NCAA Division I basketball athletes, weekly, throughout an entire season. METHODS: Twenty-two athletes (12 male, 10 female) gave a salivary sample before an afternoon practice in the middle of each week for 30 consecutive weeks, beginning in the pre-season and ending one week after the end of post-season competition. Salivary samples were assayed for T and C. Additionally, a composite value composed of Z-scores (COMP) for weekly practice minutes, game minutes, resistance training repetitions, academic stress, and travel stress was used in an attempt to quantify weekly cumulative stress so that an increase in COMP suggested an increase in cumulative stress. One-way RM ANOVA with LSD pairwise comparisons were used to determine which weekly values were different (α=.05) from the season average. RESULTS: For T, 10 weeks were different from baseline (5.1 nmol/L) for men while 4 weeks were different from baseline (2.2 nmol/L) for women. For C, 11 weeks were different from baseline (9.0 nmol/L) for men while 4 weeks were different from baseline (6.5 nmol/L) for women. For TC, weeks 7 (p=.007), 17 (p=.007), and 25 (p=.005) were different from baseline (TC=0.69) for men while weeks 6 (p=.004), 16 (p=.024), 24 (p=.003), and 27 (p=.008) were significantly different from baseline (TC=0.42) for women. CONCLUSIONS: The large increase in TC at Wk7 (men) suggested that these athletes were recovered from stressful pre-season training and physiologically prepared for the first week of regular season competition. The decrease in TC at Wk17 (men), despite the current win-streak, suggests that the lengthy season was having a physical effect on the student-athletes. Despite a brief 3-game losing streak during Wks20-21, TC was not significantly impacted (men). Finally, following a decrease in TC before post-season competition and a trend towards a decrease in Wk28 (p=.073; 1.5SD below baseline), the athletes were able to return to hormonal baseline one week after the end of the season (men). For women, during Wk6, one week prior to the first exhibition game, TC was below baseline and corresponded with an increase in COMP. However, TC returned to baseline by Wk7, which was the first week of exhibition play. During Wk16, which was collected the week after holiday break, TC was below baseline despite a decrease in COMP. During Week 24, TC was below baseline and corresponded with an increase in COMP. During Wk27, which was collected immediately before the team's first match of the NCAA tournament, TC was below baseline and corresponded with a decrease in COMP. However, the athletes returned to baseline during the tournament and remained at baseline up to and beyond their 4th round elimination. While these athletes experienced significant decreases in TC throughout the season, the overall hormonal profile appeared to remain stable compared to baseline despite constant variation in cumulative student-athlete stress and also suggested that the athletes were able to return to hormonal baseline by the end of the season. PRACTICAL APPLICATIONS: The methods of this study can be used for monitoring fatigue management by assessing how one's athletes adapt to stressful pre-season training and whether or not they recover in time for regular season play, in addition to how the athletes handle the stressors of the competitive season, and is useful for female athletes

Appropriate Loads for Peak-Power During Resisted Sprinting on a Non-Motorized Treadmill

The purpose of this study was to determine the load which allows the highest peak power for resisted sprinting on a non-motorized treadmill and to determine if other variables are related to individual differences. Thirty college students were tested for vertical jump, vertical jump peak and mean power, 10 m sprint, 20 m sprint, leg press 1 RM, leg press 1 RM relative to body weight, leg press 1 RM relative to lean body mass, leg press 1 RM power, and leg press power at 80% of 1 RM. Participants performed eight resisted sprints on a non-motorized treadmill, with increasing relative loads expressed as percent of body weight. Sprint peak power was measured for each load. Pearson correlations were used to determine if relationships between the sprint peak power load and the other variables were significant. The sprint peak power load had a mode of 35% with 73% of all participants having a relative sprint peak power load between 25-35%. Significant correlations occurred between sprint peak power load and body weight, lean body mass, vertical jump peak and mean power, leg press 1 RM, leg press 1 RM relative to lean body mass, leg press 1 RM power, and leg press power at 80% of 1 RM (r = 0.44, 0.43, 0.39, 0.37, 0.47, 0.39, 0.46, and 0.47, respectively). Larger, stronger, more powerful athletes produced peak power at a higher relative load during resisted sprinting on a nonmotorized treadmill

Single photon production by rephased amplified spontaneous emission

The production of single photons using rephased amplified spontaneous emission is examined. This process produces single photons on demand with high efficiency by detecting the spontaneous emission from an atomic ensemble, then applying a population-inverting pulse to rephase the ensemble and produce a photon echo of the spontaneous emission events. The theoretical limits on the efficiency of the production are determined for several variants of the scheme. For an ensemble of uniform optical density, generating the initial spontaneous emission and its echo using transitions of different strengths is shown to produce single photons at 70% efficiency, limited by reabsorption. Tailoring the spatial and spectral density of the atomic ensemble is then shown to prevent reabsorption of the rephased photon, resulting in emission efficiency near unity

Single photon production by rephased amplified spontaneous emission

The production of single photons using rephased amplified spontaneous emission is examined. This process produces single photons on demand with high efficiency by detecting the spontaneous emission from an atomic ensemble, then applying a population-inverting pulse to rephase the ensemble and produce a photon echo of the spontaneous emission events. The theoretical limits on the efficiency of the production are determined for several variants of the scheme. For an ensemble of uniform optical density, generating the initial spontaneous emission and its echo using transitions of different strengths is shown to produce single photons at 70% efficiency, limited by reabsorption. Tailoring the spatial and spectral density of the atomic ensemble is then shown to prevent reabsorption of the rephased photon, resulting in emission efficiency near unity

Cell-cell communication enhances the capacity of cell ensembles to sense shallow gradients during morphogenesis

Collective cell responses to exogenous cues depend on cell-cell interactions. In principle, these can result in enhanced sensitivity to weak and noisy stimuli. However, this has not yet been shown experimentally, and, little is known about how multicellular signal processing modulates single cell sensitivity to extracellular signaling inputs, including those guiding complex changes in the tissue form and function. Here we explored if cell-cell communication can enhance the ability of cell ensembles to sense and respond to weak gradients of chemotactic cues. Using a combination of experiments with mammary epithelial cells and mathematical modeling, we find that multicellular sensing enables detection of and response to shallow Epidermal Growth Factor (EGF) gradients that are undetectable by single cells. However, the advantage of this type of gradient sensing is limited by the noisiness of the signaling relay, necessary to integrate spatially distributed ligand concentration information. We calculate the fundamental sensory limits imposed by this communication noise and combine them with the experimental data to estimate the effective size of multicellular sensory groups involved in gradient sensing. Functional experiments strongly implicated intercellular communication through gap junctions and calcium release from intracellular stores as mediators of collective gradient sensing. The resulting integrative analysis provides a framework for understanding the advantages and limitations of sensory information processing by relays of chemically coupled cells.Comment: paper + supporting information, total 35 pages, 15 figure

Endocrine responses and acute mTOR pathway phosphorylation to resistance exercise with leucine and whey

Leucine ingestion reportedly activates the mTOR pathway in skeletal muscle, contributing to a hypertrophy response. The purpose of the study was to compare the post-resistance exercise effects of leucine and whey protein supplementation on endocrine responses and muscle mTOR pathway phosphorylation. On visit 1, subjects (X±SD; n=20; age=27.8±2.8yrs) provided baseline blood samples for analysis of cortisol, glucose and insulin; a muscle biopsy of the vastus lateralis muscle to assess mTOR signaling pathway phosphorylation; and were tested for maximum strength on the leg press and leg extension exercises. For visits 2 and 3, subjects were randomized in a double-blind crossover design to ingest either leucine and whey protein (10g+10g; supplement) or a non-caloric placebo. During these visits, 5 sets of 10 repetitions were performed on both exercises, immediately followed by ingestion of the supplement or placebo. Blood was sampled 30 min post-, and a muscle biopsy 45 min post-exercise. Western blots quantified total and phosphorylated proteins. Insulin increased (α<.05) with supplementation with no change in glucose compared to placebo. Relative phosphorylation of AKT and rpS6 were greater with leucine and whey supplementation compared to placebo. Supplementation of leucine and whey protein immediately after heavy resistance exercise increases anabolic signaling in human skeletal muscle

Enhanced ultrafast X-ray diffraction by transient resonances

Diffraction-before-destruction imaging with single ultrashort X-ray pulses has the potential to visualise non-equilibrium processes, such as chemical reactions, at the nanoscale with sub-femtosecond resolution in the native environment without the need of crystallization. Here, a nanospecimen partially diffracts a single X-ray flash before sample damage occurs. The structural information of the sample can be reconstructed from the coherent X-ray interference image. State-of-art spatial resolution of such snapshots from individual heavy element nanoparticles is limited to a few nanometers. Further improvement of spatial resolution requires higher image brightness which is ultimately limited by bleaching effects of the sample. We compared snapshots from individual 100 nm Xe nanoparticles as a function of the X-ray pulse duration and incoming X-ray intensity in the vicinity of the Xe M-shell resonance. Surprisingly, images recorded with few femtosecond and sub-femtosecond pulses are up to 10 times brighter than the static linear model predicts. Our Monte-Carlo simulation and statistical analysis of the entire data set confirms these findings and attributes the effect to transient resonances. Our simulation suggests that ultrafast form factor changes during the exposure can increase the brightness of X-ray images by several orders of magnitude. Our study guides the way towards imaging with unprecedented combination of spatial and temporal resolution at the nanoscale

US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report

This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in Dark Matter" held at University of Maryland on March 23-25, 2017.Comment: 102 pages + reference