A dense ring of the trans-Neptunian object Quaoar outside its Roche limit.

Planetary rings are observed not only around giant planets1, but also around small bodies such as the Centaur Chariklo2 and the dwarf planet Haumea3. Up to now, all known dense rings were located close enough to their parent bodies, being inside the Roche limit, where tidal forces prevent material with reasonable densities from aggregating into a satellite. Here we report observations of an inhomogeneous ring around the trans-Neptunian body (50000) Quaoar. This trans-Neptunian object has an estimated radius4 of 555 km and possesses a roughly 80-km satellite5 (Weywot) that orbits at 24 Quaoar radii6,7. The detected ring orbits at 7.4 radii from the central body, which is well outside Quaoar's classical Roche limit, thus indicating that this limit does not always determine where ring material can survive. Our local collisional simulations show that elastic collisions, based on laboratory experiments8, can maintain a ring far away from the body. Moreover, Quaoar's ring orbits close to the 1/3 spin-orbit resonance9 with Quaoar, a property shared by Chariklo's2,10,11 and Haumea's3 rings, suggesting that this resonance plays a key role in ring confinement for small bodies.

Pitching Behaviors in Youth Fast-Pitched Softball: High Pitching Volumes With Unequal Pitch Counts Among Pitchers are Common.

BACKGROUND: Softball is a popular sport among youth female athletes. While youth baseball has well-established, evidence-based pitching guidelines, youth softball pitching guidelines lack both evidence and enforcement. Adherence to pitch count limits in youth softball is infrequent and results in pitchers with exceedingly high pitching volumes. METHODS: Pitch counts for youth fast-pitch softball teams competing for 1 consecutive year between January 2018 to December 2019 in age groups 8 and under (8U) to 14 and under (14U) were collected. Pitching volume was assessed based on individual games, single calendar days, and tournaments in which games are played on 2 or more consecutive days. Pitchers on teams were subdivided based on pitch count volumes and compared using a logarithmic transformation and geometric mean. RESULTS: Data was collected for 10 teams from each age division resulting in analysis of 538 pitchers on 70 teams. The average pitcher threw 813 pitches per year and appeared in 20.0% of games while the average highest volume pitcher threw 2500 pitches per year and appeared in 54.5% of games. On average, the highest volume pitcher on each team threw 40% of all team pitches, while the 3 highest volume pitchers combined threw 82% of all team pitches. The average and high-volume pitcher threw pitches in 2 or more games on the same day in 37.5% and 48.6% of possible games while pitching 2 or more consecutive days in 64.0% and 79.6% of possible games, respectively. CONCLUSIONS: Softball pitchers throw high volumes of pitches while also pitching multiple days consecutively. A disparity among pitchers on softball teams exists as 40% of team pitches are thrown by 1 player and over 80% of team pitches are thrown by the top 3 pitchers. These high-volume pitchers may be engaging in unsustainable pitching practices that could predispose to injury. LEVEL OF EVIDENCE: Level IV-cross-sectional.

Laboratory and field evaluation of acetic acid-based lures for male Asian citrus psyllid, Diaphorina citri.

The Asian citrus psyllid (ACP) is a vector of a pathogen associated with greening and thus a major problem in citriculture worldwide. Lures are much needed for improving ACP trapping systems for monitoring populations and surveillance. Previously, we have identified acetic acid as a putative sex pheromone and measured formic acid- and propionic acid-elicited robust electroantennographic responses. We have now thoroughly examined in indoor behavioral assays (4-way olfactometer) and field tests the feasibility of these three semiochemicals as potential lures for trapping ACP. Formic acid, acetic acid, and propionic acid at appropriate doses are male-specific attractants and suitable lures for ACP traps, but they do not act synergistically. An acetic acid-based homemade lure, prepared by impregnating the attractant in a polymer, was active for a day. A newly developed slow-release formulation had equal performance but lasted longer, thus leading to an important improvement in ACP trap capture at low population densities.

Dehydration Impairs Cycling Performance, Independently of Thirst: A Blinded Study.

PURPOSE: The aim of the present study was to examine the effect of dehydration on exercise performance independently of thirst with subjects blinded of their hydration status. METHODS: Seven male cyclists (weight, 72 ± 9 kg; body fat, 14% ± 6%; peak oxygen uptake, 59.4 ± 6 mL·kg·min) exercised for 2 h on a cycle ergometer at 55% peak oxygen uptake, in a hot-dry environment (35°C, 30% relative humidity), with a nasogastric tube under euhydrated-non-thirst (EUH-NT) and dehydrated-non-thirst (DEH-NT) conditions. In both trials, thirst was matched by drinking 25 mL of water every 5 min (300 mL·h). In the EUH-NT trial, sweat losses were fully replaced by water via the nasogastric tube (calculated from the familiarization trial). After the 2 h of steady state, the subjects completed a 5-km cycling time trial at 4% grade. RESULTS: Body mass loss for the EUH-NT and DEH-NT after the 2 h was -0.2% ± 0.6% and -2.2% ± 0.4%, whereas after the 5-km time trial, it was -0.7% ± 0.5% and 2.9% ± 0.4%, respectively. Thirst (35 ± 30 vs 42 ± 31 mm) and stomach fullness (46 ± 21 vs 35 ± 20 mm) did not differ at the end of the 2 h of steady state between EUH-NT and DEH-NT trials (P > 0.05). Subjects cycled faster during the 5-km time trial in the EUH-NT trial compared with the DEH-NT trial (23.2 ± 1.5 vs 22.3 ± 1.8 km·h, P < 0.05), by producing higher-power output (295 ± 29 vs 276 ± 29 W, P < 0.05). During the 5-km time trial, core temperature was higher in the DEH-NT trial (39.2°C ± 0.7°C) compared with the EUH-NT trial (38.8°C ± 0.2°C; P > 0.05). CONCLUSIONS: These data indicated that hypohydration decreased cycling performance and impaired thermoregulation independently of thirst, while the subjects were unaware of their hydration status.

High-intensity ultraendurance promotes early release of muscle injury markers.

OBJECTIVE: To evaluate the impact of high-intensity ultraendurance (HIU) cycling, using it as a possible way to understand muscle injury kinetics and blood immune cells' release during high-intensity prolonged exercise DESIGN: Male amateur triathletes enrolled during a cycling race of the International Bike Championship 800 km cycling relay (approximately 23 h). Each athlete alternately cycled 20-25 minutes until exhaustion and performed a total of approximately 200 km. RESULTS: Creatine kinase levels in blood reached a 300% rise in a sigmoidal pattern, while lactate dehydrogenase levels increased by 30-40% following a hyperbolic pattern. Aspartate aminotransferase and alanine aminotransferase levels increased by up to 250% and 140%, respectively. Liver injury markers such as alkaline phosphatase and gamma-glutamyltransferase remained stable. Platelets increased by 20-30% from pre-exercise, and there was no change in haematocrit during the race. White blood cells rose by nearly 200%. Leucocytes rose 210% during the race, with a major component coming from neutrophils, which increased more than 300%. Triacylglycerol levels were decreased at the finish and total cholesterol levels remained unchanged. Urate increased (by up to 35%) during the first half of the race, and urea levels increased with a different pattern, increasing by 45% in the second half. CONCLUSIONS: This study showed the blood appearance kinetics of muscle injury markers and some metabolites. It is suggested that the increase in these enzymes came primarily from muscle damage, rather than liver damage, and that white blood cells are selectively mobilised independently of haemoconcentration. The early appearance of muscle injury markers in this kind of exercise was also shown.

Glutamine protects against increases in blood ammonia in football players in an exercise intensity-dependent way.

OBJECTIVE: High-intensity and prolonged exercise significantly enhances the levels of plasma ammonia, a metabolite with toxic effects on the central nervous system. The main purpose of the present study was to evaluate the metabolic response of athletes to glutamine (Gln) and alanine (Ala) supplementation, since these amino acids have a significant influence on both anaplerosis and gluconeogenesis. METHODS: Professional football players were assigned to groups receiving either Gln or Ala supplementation (100 mg kg(-1) body weight); this supplementation was either short-term or long-term and was given immediately before exercise. The players were evaluated using two exercise protocols, one with intervals (n = 18) and the other with continuous intensity (n = 12). RESULTS: Both types of exercises increased ammonia, urate, urea and creatinine in blood. Chronic Gln supplementation partially protected against hyperammonemia after a football match (intermittent exercise: Gln -140 (SEM 13)% vs Ala -240 (SEM 37)%) and after continuous exercise at 80% of the maximum heart rate (Gln -481 (SEM 44)% vs placebo -778 (SEM 99)%). Urate increased by 10-20% in all groups, independently of supplementation. Glutamine once a day supplementation induced a greater elevation in urate as compared to alanine at the end of the game; however, long-term supplementation provoked a lesser increment in urate. Exercise induced similar increases in creatinine as compared to their respective controls in either acute or chronic glutamine administration. CONCLUSIONS: Taken together, the results suggest that chronically supplemented Gln protects against exercise-induced hyperammonemia depending on exercise intensity and supplementation duration.

Cardiac catheterization laboratory survey: 1990. Society for Cardiac Angiography and Interventions, Laboratory Performance Standards Committee.

A survey of 117 member cardiac catheterization laboratories was undertaken by the Society for Cardiac Angiography and Interventions. The survey included numbers and types of procedures, both diagnostic and interventional, in adult as well as pediatric age groups. Radiation safety, various laboratory policies, frequency of short stay, and outpatient procedures were tabulated. Report generation, training programs, administrative organization, and laboratory equipment were all included. The results were compared with a 1978 survey. Areas of concern in terms of safety of the patient and possible underutilization of laboratories were identified.

Prevalencia de los anticuerpos contra el virus A de la hepatitis (VAH) en donantes de sangre de 13 países y territorios del hemisferio occidental / Prevalence of antibodies to hepatitis A virus (HAV) in blood donors of 13 Western Hemisphere countries and territories

Los resultados de una encuesta con 7.342 muestras de sangre de 13 países y territorios de las Américas indican una elevada prevalencia de los anticuerpos contra el virus A de la hepatitis en esa Región. Los resultados señalan también una correlación significativa entre la ausencia de dichos anticuerpos y la ausencia de marcadores indicativos de infección por el virus B de la hepatitis (AU)

Prevalencia de los anticuerpos contra el virus A de la hepatitis (VAH) en donantes de sangre de 13 paises y territorios del Hemisferio Occidental. / Prevalence of antibodies to hepatitis A virus (HAV) in blood donors of 13 countries and territories of the Western-Hemisphere

Los resultados de una encuesta con 7,342 muestras de sangur de 13 paises y territorios de las Americas indican una elevada prevalencia de los anticuerpos contra el virus A de la hepatitis en esa Region. Los resultados senalan tambien una correlacion significativa entre la ausencia de dichos anticuerpos y la ausencia de marcadores indicativos de infeccion por el virus B de la hepatitis