Force and acceleration characteristics of military foot drill: implications for injury risk in recruits

Background: Foot drill involving marching and drill manoeuvres is conducted regularly during basic military recruit training. Characterising the biomechanical loading of foot drill will improve our understanding of the contributory factors to lower limb overuse injuries in recruits. Aim: Quantify and compare forces, loading rates and accelerations of British Army foot drill, within and between trained and untrained personnel. Methods: 24 trained soldiers (12 men and 12 women; TRAINED) and 12 civilian men (UNTRAINED) performed marching and five drill manoeuvres on force platforms; motion capture recorded tibial position. Peak vertical impact force (PF), peak vertical loading rate (PLR), expressed as multiples of body weight (BW) and peak tibial impact acceleration (PTA) were recorded. Results: Drill manoeuvre PF, PLR and PTA were similar, but higher in TRAINED men (PF, PLR: p<0.01; PTA: p<0.05). Peak values in TRAINED men were shown for the halt (mean (SD); PF: 6.5 (1.5) BW; PLR: 983 (333) BW/s PTA; PTA: 207 (57) m/s2) and left turn (PF: 6.6 (1.7) BW; PLR: 928 (300) BW/s; 184 (62) m/s2). Marching PF, PLR, PTA were similar between groups and lower than all drill manoeuvres (PF: 1.1–1.3 BW; PLR: 42–70 BW/s; p<0.01; PTA: 23–38 m/s2; p<0.05). Conclusions: Army foot drill generates higher forces, loading rates and accelerations than activities such as running and load carriage, while marching is comparable to moderate running (10.8 km/h). The large biomechanical loading of foot drill may contribute to the high rate of overuse injuries during initial military training, and strategies to regulate/reduce this loading should be explored

Dietary Plant Sterol Esters Must Be Hydrolyzed to Reduce Intestinal Cholesterol Absorption in Hamsters

Background: Elevated concentrations of LDL cholesterol are associated with the development of atherosclerosis and therefore are considered an important target for intervention to prevent cardiovascular diseases. The inhibition of cholesterol absorption in the small intestine is an attractive approach to lowering plasma cholesterol, one that is addressed by drug therapy as well as dietary supplementation with plant sterols and plant sterol esters (PSEs). Objective: This study was conducted to test the hypothesis that the cholesterol-lowering effects of PSE require hydrolysis to free sterols (FSs). Methods: Male Syrian hamsters were fed atherogenic diets (AIN-93M purified diet containing 0.12% cholesterol and 8% coconut oil) to which one of the following was added: no PSEs or ethers (control), 5% sterol stearate esters, 5% sterol palmitate esters (PEs), 5% sterol oleate esters (OEs), 5% sterol stearate ethers (STs; to mimic nonhydrolyzable PSE), or 3% FSs plus 2% sunflower oil. The treatments effectively created a spectrum of PSE hydrolysis across which cholesterol metabolism could be compared. Metabolic measurements included cholesterol absorption, plasma and liver lipid concentration, and fecal neutral sterol and bile acid excretion. Results: The STs and the PEs and SEs were poorly hydrolyzed (1.69–4.12%). In contrast,OEs were 88.3% hydrolyzed. The percent hydrolysis was negatively correlated with cholesterol absorption (r=20.85; P \u3c 0.0001) and positively correlated with fecal cholesterol excretion (r = 0.92; P \u3c 0.0001), suggesting that PSE hydrolysis plays a central role in the cholesterol-lowering properties of PSE. Conclusions: Our data on hamsters suggest that PSE hydrolysis and the presence of FSs is necessary to induce an optimum cholesterol-lowering effect and that poorly hydrolyzed PSEs may lower cholesterol through an alternative mechanism than that of competition with cholesterol for micelle incorporation

Stochastic method for in-situ damage analysis

Based on the physics of stochastic processes we present a new approach for structural health monitoring. We show that the new method allows for an in-situ analysis of the elastic features of a mechanical structure even for realistic excitations with correlated noise as it appears in real-world situations. In particular an experimental set-up of undamaged and damaged beam structures was exposed to a noisy excitation under turbulent wind conditions. The method of reconstructing stochastic equations from measured data has been extended to realistic noisy excitations like those given here. In our analysis the deterministic part is separated from the stochastic dynamics of the system and we show that the slope of the deterministic part, which is linked to mechanical features of the material, changes sensitively with increasing damage. The results are more significant than corresponding changes in eigenfrequencies, as commonly used for structural health monitoring.Comment: This paper is accepted by European Physical Journal B on November 2. 2012. 5 pages, 5 figures, 1 tabl

Diarrhoea among children aged under five years and risk factors in informal settlements: a cross-sectional study in Cape Town, South Africa

Background: There is limited data on the association between diarrhoea among children aged under five years (U5D) and water use, sanitation, hygiene, and socio-economics factors in low-income communities. The study investigated U5D and the associated risk factors in the Zeekoe catchment in Cape Town, South Africa. Methods: A cross-sectional study was conducted in 707 households in six informal settlements (IS) two formal settlements (FS) (March-June 2017). Results: Most IS households used public taps (74.4%) and shared toilets (93.0%), while FS households used piped water on premises (89.6%) and private toilets (98.3%). IS respondents had higher average hand-washing scores than those of FS (0.04 vs

Mineral maturity and crystallinity index are distinct characteristics of bone mineral

The purpose of this study was to test the hypothesis that mineral maturity and crystallinity index are two different characteristics of bone mineral. To this end, Fourier transform infrared microspectroscopy (FTIRM) was used. To test our hypothesis, synthetic apatites and human bone samples were used for the validation of the two parameters using FTIRM. Iliac crest samples from seven human controls and two with skeletal fluorosis were analyzed at the bone structural unit (BSU) level by FTIRM on sections 2–4 lm thick. Mineral maturity and crystallinity index were highly correlated in synthetic apatites but poorly correlated in normal human bone. In skeletal fluorosis, crystallinity index was increased and maturity decreased, supporting the fact of separate measurement of these two parameters. Moreover, results obtained in fluorosis suggested that mineral characteristics can be modified independently of bone remodeling. In conclusion, mineral maturity and crystallinity index are two different parameters measured separately by FTIRM and offering new perspectives to assess bone mineral traits in osteoporosis

Dietary Plant Sterol Esters Must Be Hydrolyzed to Reduce Intestinal Cholesterol Absorption in Hamsters

Background: Elevated concentrations of LDL cholesterol are associated with the development of atherosclerosis and therefore are considered an important target for intervention to prevent cardiovascular diseases. The inhibition of cholesterol absorption in the small intestine is an attractive approach to lowering plasma cholesterol, one that is addressed by drug therapy as well as dietary supplementation with plant sterols and plant sterol esters (PSEs). Objective: This study was conducted to test the hypothesis that the cholesterol-lowering effects of PSE require hydrolysis to free sterols (FSs). Methods: Male Syrian hamsters were fed atherogenic diets (AIN-93M purified diet containing 0.12% cholesterol and 8% coconut oil) to which one of the following was added: no PSEs or ethers (control), 5% sterol stearate esters, 5% sterol palmitate esters (PEs), 5% sterol oleate esters (OEs), 5% sterol stearate ethers (STs; to mimic nonhydrolyzable PSE), or 3% FSs plus 2% sunflower oil. The treatments effectively created a spectrum of PSE hydrolysis across which cholesterol metabolism could be compared. Metabolic measurements included cholesterol absorption, plasma and liver lipid concentration, and fecal neutral sterol and bile acid excretion. Results: The STs and the PEs and SEs were poorly hydrolyzed (1.69–4.12%). In contrast,OEs were 88.3% hydrolyzed. The percent hydrolysis was negatively correlated with cholesterol absorption (r=20.85; P \u3c 0.0001) and positively correlated with fecal cholesterol excretion (r = 0.92; P \u3c 0.0001), suggesting that PSE hydrolysis plays a central role in the cholesterol-lowering properties of PSE. Conclusions: Our data on hamsters suggest that PSE hydrolysis and the presence of FSs is necessary to induce an optimum cholesterol-lowering effect and that poorly hydrolyzed PSEs may lower cholesterol through an alternative mechanism than that of competition with cholesterol for micelle incorporation

Mitochondrial and nuclear genes suggest that stony corals are monophyletic but most families of stony corals are not (Order Scleractinia, Class Anthozoa, Phylum Cnidaria)

Modern hard corals (Class Hexacorallia; Order Scleractinia) are widely studied because of their fundamental role in reef building and their superb fossil record extending back to the Triassic. Nevertheless, interpretations of their evolutionary relationships have been in flux for over a decade. Recent analyses undermine the legitimacy of traditional suborders, families and genera, and suggest that a non-skeletal sister clade (Order Corallimorpharia) might be imbedded within the stony corals. However, these studies either sampled a relatively limited array of taxa or assembled trees from heterogeneous data sets. Here we provide a more comprehensive analysis of Scleractinia (127 species, 75 genera, 17 families) and various outgroups, based on two mitochondrial genes (cytochrome oxidase I, cytochrome b), with analyses of nuclear genes (ßtubulin, ribosomal DNA) of a subset of taxa to test unexpected relationships. Eleven of 16 families were found to be polyphyletic. Strikingly, over one third of all families as conventionally defined contain representatives from the highly divergent "robust" and "complex" clades. However, the recent suggestion that corallimorpharians are true corals that have lost their skeletons was not upheld. Relationships were supported not only by mitochondrial and nuclear genes, but also often by morphological characters which had been ignored or never noted previously. The concordance of molecular characters and more carefully examined morphological characters suggests a future of greater taxonomic stability, as well as the potential to trace the evolutionary history of this ecologically important group using fossils