Kinematics of heelstrike during walking and carrying: implications for slip resistance testing

Slip resistance measurements of shoes and floors are used to evaluate the potential for slip and fall injuries. These measurements are believed to have increased validity when they more closely reflect actual heelstrike biomechanics during locomotion. The purpose of this study was to describe heelstrike kinematics during load carrying to provide data towards improved slip resistance testing. Foot kinematics during load carrying (unladen and carrying from 0 to 13.5 kg) at various cadences (70, 90, 100 steps/min) was recorded. Measures before, during and after heelstrike were analysed. Cadence was an important predictor for all variables measured, associated with changes from 13% to over 100%. The load carried was an important predictor for only the heel slip distance after heelstrike, but this effect needs to be investigated further. These results can be used to improve the fidelity of slip resistance measurements, which is critical to reduce slip and fall injuries in the workplace or during activities of daily living.     

Reinforcement Learning Rules in a Repeated Game

This paper examines the performance of simple reinforcement learningalgorithms in a stationary environment and in a repeated game where theenvironment evolves endogenously based on the actions of other agents. Sometypes of reinforcement learning rules can be extremely sensitive to smallchanges in the initial conditions, consequently, events early in a simulationcan affect the performance of the rule over a relatively long time horizon.However, when multiple adaptive agents interact, algorithms that performedpoorly in a stationary environment often converge rapidly to a stableaggregate behaviors despite the slow and erratic behavior of individuallearners. Algorithms that are robust in stationary environments can exhibitslow convergence in an evolving environment.     

A comment on the influence of substrates on the superfluid density of thin helium-four films atT=0

The influence of substrate potentials on the superfluid density in thin films of ⁴ He atT=0 is discussed. Estimates indicate that an observabl large reduction in _s is to be expected.     

Thermal explosion in a hot gas mixture with organic gel fuel droplets

Recent experimental evidence has uncovered the peculiar behavior of certain gel droplets which, under appropriate ambient thermal conditions, evaporate and burn in an oscillatory fashion. In this work a preliminary foray is made into the theoretical analysis of the nature of the evolution of a hot gas mixture containing organic gel fuel droplets with oscillatory evaporation within the context of thermal-explosion theory. The problem is modeled as a system of highly nonlinear singularly perturbed ordinary differential equations. Non-dimensionalization of the equations enables identification of the parameters that play a major role in determining the dynamical regimes of the system of equations. The method of integral manifolds is exploited for the analysis and it is found, that for certain parametric regions, the system exhibits new dynamical behavior that is quite different from that found for conventional liquid droplets.     

THE IMPACT OF SPATIAL VERSUS ECONOMIC MEASURES IN AN URBAN TRANSPORTATION PLAN

A multimodal model for traffic was developed by the Flemish administration. For the first time an integrated set of measures was taken into account to forecast statistics on car-traffic and the use of public transport systems during evening peak-hours. The measures can be classified in four groups: planning, infrastructure, regulation and financial. Each input is forecasted for 2010 by means of two opposite scenarios: a trend scenario and a policy (sustainable) scenario. The model was first tested for the Antwerp region on a very detailed geographical level. We sought to identify which measures had a significant influence on the results. As a result of a sensitivity analysis we conclude that even in the long run planning measures are least effective, followed by infrastructure measures that may stimulate local people to make use of public transport. Regulatory measures and especially financial measures have clearly the most significant impact on generation of passenger kilometres and modal choice during the evening rush hour.     

Evaluating the Endophenotype Model of ADHD Neuropsychological Deficit: Results for Parents and Siblings of Children With ADHD Combined and Inattentive Subtypes.

Neurogenetic models predict neuropsychological weaknesses in the relatives of children with attention-deficit/ hyperactivity disorder (ADHD). The authors examined executive and regulatory measures in 386 relatives (307 parents, 79 siblings) of children with ADHD combined type, ADHD inattentive type, and controls. Predicted deficits were seen on trailmaking (relatives of ADHD combined type only), stop-signal reaction times (relatives of girls only), and response variability (mothers only) but not on naming or output speed. Effects generally held, even with relatives' ADHD status controlled. A neuropsychologically impaired subgroup of children with ADHD had relatives with clear neuropsychological weaknesses. The authors conclude that a neurogenetic model of ADHD etiology is supportable only for a subset of executive functions and that neuropsychological heterogeneity warrants more examination in ADHD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Links Between Sex-Typed Time Use in Middle Childhood and Gender Development in Early Adolescence.

The authors studied sex-typing in the kinds (e.g., sports, handicrafts) and social contexts (same- vs. other-sex companions) of children's free time activities, and the links between sex-typed activities and gender development over 2 years. Participants were 200 White, working- and middle-class children (103 girls, 97 boys; mean age = 10.86 years). In annual home interviews, children rated their self-esteem, gender role attitudes and sex-typed personality qualities, academic interests, and school grades. During 7 nightly phone interviews each year, children reported on their activities. Boys were more sex-typed than girls in their peer activities, and children were least sex-typed in their activities with siblings. Sex-typed activities in middle childhood predicted individual differences in gender development in early adolescence (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

ILB®, a Low Molecular Weight Dextran Sulphate,Restores Glutamate Homeostasis,Amino Acid Metabolism and Neurocognitive Functions in a Rat Model of Severe Traumatic Brain Injury

In a previous study, we found that administration of ILB^®, a new low molecular weight dextran sulphate, significantly improved mitochondrial functions and energy metabolism, as well as decreased oxidative/nitrosative stress, of brain tissue of rats exposed to severe traumatic brain injury (sTBI), induced by the closed-head weight-drop model of diffused TBI. Using aliquots of deproteinized brain tissue of the same animals of this former study, we here determined the concentrations of 24 amino acids of control rats, untreated sTBI rats (sacrificed at 2 and 7 days post-injury) and sTBI rats receiving a subcutaneous ILB^® administration (at the dose levels of 1, 5 and 15 mg/kg b.w.) 30 min post-impact (sacrificed at 2 and 7 days post-injury). Additionally, in a different set of experiments, new groups of control rats, untreated sTBI rats and ILB^®-treated rats (administered 30 min after sTBI at the dose levels of 1 or 5 mg/kg b.w.) were studied for their neurocognitive functions (anxiety, locomotor capacities, short- and long-term memory) at 7 days after the induction of sTBI. Compared to untreated sTBI animals, ILB^® significantly decreased whole brain glutamate (normalizing the glutamate/glutamine ratio), glycine, serine and γ-aminobutyric acid. Furthermore, ILB^® administration restored arginine metabolism (preventing nitrosative stress), levels of amino acids involved in methylation reactions (methionine, L-cystathionine, S-adenosylhomocysteine), and N-acetylaspartate homeostasis. The macroscopic evidences of the beneficial effects on brain metabolism induced by ILB^® were the relevant improvement in neurocognitive functions of the group of animals treated with ILB^® 5 mg/kg b.w., compared to the marked cognitive decline measured in untreated sTBI animals. These results demonstrate that ILB^® administration 30 min after sTBI prevents glutamate excitotoxicity and normalizes levels of amino acids involved in crucial brain metabolic functions. The ameliorations of amino acid metabolism, mitochondrial functions and energy metabolism in ILB^®-treated rats exposed to sTBI produced significant improvement in neurocognitive functions, reinforcing the concept that ILB^® is a new effective therapeutic tool for the treatment of sTBI, worth being tested in the clinical setting.     

Microencapsulated Lactobacillus rhamnosus GG powders: relationship of powder physical properties to probiotic survival during storage

Freeze-dried commercial Lactobacillus rhamnosus GG (LGG) were encapsulated in an emulsion-based formulation stabilized by whey protein and resistant starch and either spray-dried or freeze-dried to produce probiotic microcapsules. There was no difference in loss of probiotics viability after spray drying or freeze drying. Particle size, morphology, moisture sorption, and water mobility of the powder microcapsules were examined. Particle size analysis and scanning electron microscopy showed that spray-dried LGG microcapsules (SDMC) were small spherical particles, whereas freeze-dried LGG microcapsules (FDMC) were larger nonspherical particles. Moisture sorption isotherms obtained using dynamic vapor sorption showed a slightly higher water uptake in spray-dried microcapsules. The effect of water mobility, as measured by nuclear magnetic resonance (NMR) spectroscopy, at various water activities (a(w) 0.32, 0.57, and 0.70) and probiotic viability during storage at 25 °C was also examined. Increasing the relative humidity of the environment at which the samples were stored caused an increase in water mobility and the rate of loss in viability. The viability data during storage indicated that SDMC had better storage stability compared to FDMC. Although more water was adsorbed for spray-dried than freeze-dried microcapsules, water mobility was similar for corresponding storage conditions because there was a stronger water-binding energy for spray-dried microcapsule. This possibly accounted for the improved survival of probiotics in spray-dried microcapsules.     

Influence of pectin properties and processing conditions on thermal pectin degradation

Texture degradation of fruits and vegetables during thermal processing is partly due to pectin depolymerization. In this contribution we investigate the influence of pectin properties (degree and pattern of methoxylation) and processing conditions (pH 2.0, 3.0, 5.0 and 7.0; temperatures of 80 up to 110 °C) on pectin degradation rate constants. Pectins with different degrees and patterns of methoxylation were prepared and heated, the extent of acid hydrolysis, β-elimination and demethoxylation was assayed as a function of treatment time. As the degree of methoxylation and pH decreased, β-elimination rate constants decreased while acid hydrolysis rate constants increased. Demethoxylation rate constants were minimal at pH 3.0 and increased both at lower and higher pH. Reaction rate constants were not considerably influenced by the pattern of methoxylation. All reaction rate constants increased with increasing temperature. As β-elimination rates are reduced by competing demethoxylation, both rate constants were compared. The ratio of these reaction rate constants showed no trend with pH. However, an increase in degree of methoxylation or temperature resulted in a more pronounced increase in β-elimination rate constants than in demethoxylation rate constants.