Effect of body tilt angle on fatigue and EMG activities in lower limbs during cycling

This study compared the rate of fatigue and lower limb EMG activities during high-intensity constantload cycling in upright and supine postures. Eleven active males performed seven cycling exercise tests: one upright graded test, four fatigue tests (two upright, two supine) and two EMG tests (one upright, one supine). During the fatigue tests participants initially performed a 10 s all-out effort followed by a constant-load test with 10 s all-out bouts interspersed every minute. The load for the initial two fatigue tests was 80% of the peak power (PP) achieved during the graded test and these continued until failure. The remaining two fatigue tests were performed at 20% PP and were limited to the times achieved during the 80% PP tests. During the EMG tests subjects performed a 10 s all-out effort followed by a constant-load test to failure at 80% PP. Normalised EMG activities (% maximum, NEMG) were assessed in five lower limb muscles. Maximum power and maximum EMG activity prior to each fatigue and EMG test were unaffected by posture. The rate of fatigue at 80% PP was significantly higher during supine compared with upright posture (-68 ± 14 vs. -26 ± 6 W min-1, respectively, P\0.05) and the divergence of the fatigue responses occurred by the second minute of exercise. NEMG responses were significantly higher in the supine posture by 1–4 min of exercise. Results show that fatigue is significantly greater during supine compared with upright high-intensity cycling and this effect is accompanied by a reduced activation of musculature that is active during cycling.

Chemical coding of vascular nitrergic nerves in lower vertebrates

Nitric oxide is an important regulator of blood pressure in mammals. This study provided new information on the role of nitric-oxide releasing sympathetic nerves in vascular regulation of lower vertebrates. The research outcomes advance knowledge on the potential role of these unique nerves in the control of the lower vertebrate cardiovascular system.

Bounded lower subdifferentiability optimization techniques : applications

In this article we develop a global optimization algorithm for quasiconvex programming where the objective function is a Lipschitz function which may have "flat parts". We adapt the Extended Cutting Angle method to quasiconvex functions, which reduces significantly the number of iterations and objective function evaluations, and consequently the total computing time. Applications of such an algorithm to mathematical programming problems inwhich the objective function is derived from economic systems and location problems are described. Computational results are presented.

Lower levels of physical activity in childhood associated with adult depression

Emerging evidence indicates that early life exposures influence adult health outcomes and there is cause to hypothesise a role for physical activity (PA) in childhood as a protective factor in adult depression. This study aimed to investigate the association between self-reported levels of PA in childhood and self-reported depressive illness. Lifetime depression and levels of physical activity (low/high) in childhood (<15 yr) were ascertained by self-report in 2152 adults (20–97 yr) participating in an ongoing epidemiological study in south-eastern Australia. Data were collected between 2000 and 2006. In this sample, 141 women (18.9%) and 169 men (12.0%) reported ever having a depressive episode. Low PA in childhood was associated with an increased risk of reporting depression in adulthood (OR = 1.70, 95%CI = 1.32–2.17, p < 0.001). Adjustment for age, gender and adult PA attenuated the relationship somewhat (OR = 1.35, 95%CI = 1.01–1.78, p = 0.04), however further adjustment for SES or country of birth did not affect this relationship. In this community-based study, lower levels of self-reported PA in childhood were associated with a 35% increase in odds for self-reported depression in adulthood. These results are consistent with the hypothesis that lower levels of PA in childhood may be a risk factor for adult depression.

Overweight children have a greater proportion of fat mass relative to muscle mass in the upper limbs than in the lower limbs : implications for bone strength at the distal forearm

Background: The influence of adiposity on upper-limb bone strength has rarely been studied in children, despite the high incidence of forearm fractures in this population.

Objective: The objective was to compare the influence of muscle and fat tissues on bone strength between the upper and lower limbs in prepubertal children.

Design: Bone mineral content, total bone cross-sectional area, cortical bone area (CoA), cortical thickness (CoTh) at the radius and tibia (4% and 66%, respectively), trabecular density (TrD), bone strength index (4% sites), cortical density (CoD), stress-strain index, and muscle and fat areas (66% sites) were measured by using peripheral quantitative computed tomography in 427 children (206 boys) aged 7–10 y.

Results: Overweight children (n = 93) had greater values for bone variables (0.3–1.3 SD; P < 0.0001) than did their normal-weight peers, except for CoD 66% and CoTh 4%. The between-group differences were 21–87% greater at the tibia than at the radius. After adjustment for muscle cross-sectional area, TrD 4%, bone mineral content, CoA, and CoTh 66% at the tibia remained greater in overweight children, whereas at the distal radius total bone cross-sectional area and CoTh were smaller in overweight children (P < 0.05). Overweight children had a greater fat-muscle ratio than did normal-weight children, particularly in the forearm (92 ± 28% compared with 57 ± 17%). Fat-muscle ratio correlated negatively with all bone variables, except for TrD and CoD, after adjustment for body weight (r = −0.17 to −0.54; P < 0.0001).

Conclusions: Overweight children had stronger bones than did their normal-weight peers, largely because of greater muscle size. However, the overweight children had a high proportion of fat relative to muscle in the forearm, which is associated with reduced bone strength.

Flexible multibody approach in forward dynamic simulation of locomotive strains in human skeleton with flexible lower body bones

A method for bone strain estimation is examined in this article. The flexibility of a single bone in an otherwise rigid human skeleton model has been studied previously by various authors. However, in the previous studies, the effect of the flexibility of multiple bones on the musculoskeletal model behavior was ignored. This study describes a simulation method that can be used to estimate the bone strains at both tibias and femurs of a 65-year old Caucasian male subject. The verification of the method is performed by the comparison of the results with other studies available in literature. The results of the study show good correlation with the results of previous empirical studies. A damping effect of the flexible bones on the model is also studied in this paper.

New material of coral fossils in Lower Devonian, Daerdong formation of Xainza, Tibet

The system described in the part of the coral fossils collected from Xainza area, northern Lower Devonian Dahl East group. Wrinkles coral genera and 5 species (including a new species Hunanaxonia xizangensis sp nov.) And two undetermined species; bedplate coral-shaped coral 4 4 species, including two new species the (Pachycanalicula sparcula sp nov. Paraheliolites zakangensis sp nov.) these coral fossil discovery will help to further understanding of the Early Devonian corals fauna symbiotic combination, evolution, and coral paleobiogeographic flora.

Coagulation and nano-filtration: a hybrid system for the removal of lower molecular weight organic compounds (LMWOC)

The removal of lower molecular weight organic compounds (LMWOC) from water is of increasing concern. While, nano-fi ltration (NF) is a good option, it removes only a fraction of the LMWOC. In this paper, NF experiments were conducted to remove oxalic acid and diuron in combination with coagulation using poly-aluminum chloride (PAC) as the coagulant. The results showed that this hybrid treatment system was effective in removing oxalic acid where almost a 100% removal effi ciency of oxalic acid was achieved. However, using PAC as coagulant to remove diuron from water was not effective. In order to improve the removal efficiency of diuron, 0.02 M NaCl was added to diuron and a 40% increase in the removal of diuron was achieved. Higher removal of diuron was achieved when the solution was treated with reverse osmosis (RO) when compared to the nano-filtration.