Hematological Changes Elicited by Prolonged Intermittent Aerobic Exercise

Abstract

The purpose of this study was to compare the acute and chronic effects of a strenuous work task, in a moderately high heat stress environment, upon selected hematological components. Twenty experienced long-distance runners competed in a 24-hr relay, running approximately one mile each hour in relay fashion. Food and fluid intake was allowed ad libitum during rest intervals. Blood samples were secured three times: (T1) within 1 hr prior to the start; (T2) approximately 10 min after the first mile run; and (T3) approximately 10 min after each subject completed his last mile run. Main blood variables of interest were Hb, Hct, total protein, albumin, WBC diff, Na⁺, K⁺, Cl^?, Ca⁺⁺, glucose, cholesterol, T-bilirubin, LDH, SGOT, CPK, BUN, uric acid, and creatinine. Within the limitations of this study, the following main conclusions appear warranted: (a) hemoconcentration changes between T1 and T2 may be the causative factor underlying the moderate, but significant, increases in the majority of other hematological components between T1 and T2. As hemoconcentration did not appear to increase further between T2 and T3, component changes between T2 and T3 may be due to other causative factors; (b) the data from LDH, CPK, SGOT, BUN, uric acid and bilirubin is suggestive of muscle tissue damage and hemolysis.     

Solving the mystery of vanishing rivers in China

A major controversy was sparked worldwide by a recent national water census claiming that the number of Chinese rivers with watersheds ≥100 km² was less than half the previous estimate of 50 000 rivers, which also stimulates debates on the potential causes and consequences. Here, we estimated the number of rivers in terms of stream-segmentation characteristics described by Horton, Strahler and Shreve stream-order rules, as well as their mixed mode for named rivers recorded in the Encyclopedia of Rivers and Lakes in China. As a result, the number of ‘vanishing rivers’ has been found to be highly relevant to statistical specifications in addition to the erroneous inclusion of pseudo-rivers primarily generated in arid or frost-thaw areas. The modified Horton stream-order scheme reasonably depicts the configuration of complete natural streams from headwater to destination, while the Strahler largely projects the fragmentation of the named river networks associated with human aggregation to the hierarchical river systems.     

Disruption of temporal discrimination and the choose-short effect

The present experiment examined the effects of several disruptors on temporal discrimination. Pigeons responded under a 0-delay symbolic matching-to-sample procedure in which responses to one key color were reinforced following the presentation of four shorter sample durations, and responses to another key color were reinforced following the presentation of four longer sample durations. Steady-state performance was disrupted by presession feeding, intertrial-interval food, visual distraction, and extinction. All disruptors decreased temporal-discrimination accuracy. Analyses of the fitted cumulative normal functions indicated that decreases in accuracy were produced mainly by decreases in overall stimulus control rather than specific effects on timing. In addition, all disruptors selectively decreased accuracy on long-sample trials—a choose-short effect. This effect is interpreted in terms of decreased attention to the samples under disruption. Current theories of the choose-short effect do not appear to easily account for these results.     

Want to improve sexual health education for girls? Include body image

Research suggests body image is related to sexual behaviors, which can impact sexual health across the lifespan. This paper aims to explain the necessity for including body image content in sexuality education to improve outcomes among girls. Our recommendations, supported by theory and empirical research include (a) an assessment of existing curricula; (b) designing new, theoretically-informed curricula; (c) using innovative technology in sex education; (d) rigorous evaluation of existing and new curricula; and (e) revising the National Sexuality Education Standards. These recommendations are discussed after providing the necessary background and rationale.