Cardiac parasympathetic activity may be non-invasively investigated using heart rate variability (HRV), although HRV is not widely accepted to reflect sympathetic activity. Instead, cardiac sympathetic activity may be investigated using systolic time intervals (STI), such as the pre-ejection period. Although these autonomic indices are typically measured during rest, the “reactivity hypothesis” suggests that investigating responses to a stressor (e.g., exercise) may be a valuable monitoring approach in clinical and high-performance settings. However, when interpreting these indices it is important to consider how the exercise dose itself (i.e., intensity, duration, and modality) may influence the response. Therefore, the purpose of this investigation was to review the literature regarding how the exercise dosage influences these autonomic indices during exercise and acute post-exercise recovery. There are substantial methodological variations throughout the literature regarding HRV responses to exercise, in terms of exercise protocols and HRV analysis techniques. Exercise intensity is the primary factor influencing HRV, with a greater intensity eliciting a lower HRV during exercise up to moderate-high intensity, with minimal change observed as intensity is increased further. Post-exercise, a greater preceding intensity is associated with a slower HRV recovery, although the dose-response remains unclear. A longer exercise duration has been reported to elicit a lower HRV only during low-moderate intensity and when accompanied by cardiovascular drift, while a small number of studies have reported conflicting results regarding whether a longer duration delays HRV recovery. “Modality” has been defined multiple ways, with limited evidence suggesting exercise of a greater muscle mass and/or energy expenditure may delay HRV recovery. STI responses during exercise and recovery have seldom been reported, although limited data suggests that intensity is a key determining factor. Concurrent monitoring of HRV and STI may be a valuable non-invasive approach to investigate autonomic stress reactivity; however, this integrative approach has not yet been applied with regards to exercise stressors.

Rugby league players have a lower prevalence of depression compared with studies of the general population and other athletes, but a higher prevalence of GAD, and high rates of alcohol misuse. Clubs may consider implementing regular screening for these conditions. Further prospective research to determine causality of independent factors is required.

Scrapie, a spongiform encephalopathy of sheep and goats, is caused by a poorly understood transmissible agent in which no nucleic acid has been conclusively identified. Biochemical characterization of agent derived from animal tissues has not been precise because of the tenacious association of the agent with tissue components. As an approach toward obtaining homogeneous preparations of agent generated in vitro, we cloned scrapie-infected neuroblastoma cells. By frequency analysis, nearly every cell in expanded cultures contained scrapie agent. We also analyzed cell-dose infectivity relationships and developed a standard curve which allowed various cultures to be compared. Since a proteinase K (PK)-resistant form of a protein designated prion protein (PrP) has been found in partially purified preparations of scrapie agent from infected animal spleens and brains, we sought to identify this protein in cell cultures. No PK-resistant PrP was found in infected or uninfected cultures, although the PK-sensitive PrP was readily detected. These results suggested that PK-resistant PrP may not be an essential component of the infectious scrapie agent.

Preceding exercise intensity has a graded effect on recovery HRV measures reflecting cardiac vagal activity, even after correcting for the underlying HR. The immediate recovery following exercise is a potentially useful period to investigate autonomic activity, as multiple levels of autonomic activity can be clearly differentiated between using HRV. When investigating post-exercise HRV it is critical to account for the relative exercise intensity.

A microscopic confirmation of the fractional statistics of the quasiparticles in the fractional quantum Hall effect has so far been lacking. We calculate the statistics of the composite-fermion quasiparticles at ν = 1/3 and ν = 2/5 by evaluating the Berry phase for a closed loop encircling another composite-fermion quasiparticle. A careful consideration of subtle perturbations in the trajectory due to the presence of an additional quasiparticle is crucial for obtaining the correct value of the statistics. The conditions for the applicability of the fractional statistics concept are discussed.The fractional statistics concept of Leinaas and Myrheim[1] relies on the property that when particles with infinitely strong short range repulsion are confined in two dimensions, paths with different winding numbers are topologically distinct and cannot be deformed into one another. The particles are said to have statistics θ if a path independent phase 2πθ results when one particle goes around another in a complete loop. A half loop is equivalent to an exchange of particles, assuming translational invariance, which produces a phase factor e iπθ = (−1) θ . Non-integral values of θ imply fractional statistics. There are no fundamental particles in nature that obey fractional statistics. Any fractional statistics objects will have to be emergent collective particles of a non-trivial condensed matter state. Furthermore, they will be necessarily confined to two dimensions: in higher dimensions the notion of a particle going around another is topologically ill defined, because any loop can be shrunk to zero without ever crossing another particle.Even though the explanation of the fractional quantum Hall effect[2] (FQHE) and numerous other remarkable phenomena follows from the composite fermion theory with no mention of fractional statistics [3], fractional statistics is believed to be one of the consequences of incompressibility at a fractional filling [4,5,6], and may possibly be observable in an experiment specifically designed for this purpose. For Laughlin's quasiholes [7] at ν = 1/m, m odd, the statistics was derived explicitly by Arovas, Schrieffer, and Wilczek[4] in a Berry phase calculation, but a similar demonstration of fractional statistics has been lacking at other fractions, or even for the quasiparticles at ν = 1/m. The need for a microscopic confirmation was underscored by Kjønsberg and Myrheim[8] who showed that, with Laughlin's wave function, the quasiparticles at ν = 1/m do not possess well-defined statistics. The reason for the discrepancy remains unclear, but it illustrates that the fractional statistics is rather fragile and cannot be taken for granted.The objective of this article is to revisit the issue armed with the microscopic composite-fermion (CF) theory of the FQHE [9]. A step in that direction has been taken by Kjønsberg and Leinaas[10], whose calculation of the statistics of the "unprojected" CF quasiparticle of ν = 1/m, the wave function for which is different from that of Laughlin's, produced a...

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Contemporary meta-analyses have generally demonstrated a positive effect of sodium bicarbonate (NaHCO 3) supplementation on exercise performance. However, despite these claims, there is limited data on contrasting individualized and standardized timing of NaHCO 3 ingestion prior to exercise to further enhance performance outcomes. Purpose: To determine whether NaHCO 3 ingestion timing impacts 2,000-m rowing time-trial (TT) performance in elite-level rowers (Senior National team including Olympic/World Championships level) adhering to their own individualized pre-race strategies (e.g. nutrition, warm-up, etc.). Methods: Twenty three (n = 23) rowers across two research centers (using the exact same methods/protocols) completed three trials: NaHCO 3 loading profile at rest to determine the individual's time-to-peak bicarbonate concentration [HCO − 3 ], followed by two randomized 0.3 g•kgBM −1 NaHCO 3 supplementation experimental trials conducted at different time points [consensus timing (CON): TT performed 60 min post-NaHCO 3 ingestion; and individualized peak (IP): TT performed at the rower's individual peak [HCO − 3 ] determined from the profiling trial post-NaHCO 3 ingestion]. Results: There was a significant mean difference of +2.9 [± 0.4 mmol•L −1 HCO − 3 for IP vs. CON (95% CI 2.0 to 3.8 mmol•L −1); p = 0.02; d = 1.08] at pre warm-up, but not immediately prior to the TT (post warm-up). Performance times were significantly different between IP (367.0 ± 10.5 s) vs. CON (369.0 ± 10.3 s); p = 0.007; d = 0.15). Conclusions: The present study demonstrated a small but significant performance effect of an individualized NaHCO 3 ingestion strategy. Similarities after warm-up between pre-TT sHCO − 3 values (CON ∼ + 5.5 mmol•L −1 ; IP ∼ + 6 mmol•L −1), however, would suggest this effect was not a result of any meaningful differences in blood alkalinity.