Search

Patterns of interjoint coordination in the kicking legs of taekwondo players were investigated to understand movement pattern variability as a functional property of skill level. Elite and nonelite players performed roundhouse kicks against a custom-built moving target fitted with an accelerometer, and movements were recorded by motion capture. Average foot segment velocities of 13.6 and 11.4 m/s were recorded for elite and nonelite players, respectively (P g (P P

The purpose of this study was to evaluate the degree to which personalized cognitive strategy instruction (PCSI) assisted students with prolonged concussion symptoms (PCS) to achieve functional and academic-related goals. It was hypothesized that goal attainment on collaboratively developed functional goals and selected scores on the pre/post outcome measurements would improve following the delivery of PCSI. A non-concurrent multiple baseline design was utilized across three female participants ages 13-16. The weekly status tracking measurement of participant performance served as the primary measurement analysed to determine the existence of a functional relation between the addition of PCSI to psychoeducation and the achievement of participant outcome. Although visual analysis of the plotted status tracking data did not support the existence of a functional relation, all three participants met or exceeded functional goals on their goal attainment scales. A Tau-U analysis supported a small treatment effect. The positive response to the intervention from two of the three participants in addition to goal attainment for all three participants suggests PCSI has potential to mitigate cognitive challenges in adolescents with PCS. Implications for future research and methods to promote ecological measurement of intervention effects are discussed.

This study aimed to examine the player positions that are more dominant in positional attack. A total of six international matches were selected, all matches involving MOL-Pick Szeged handball club. For the 12 graphs obtained from social network analysis of MOL-Pick Szeged and each of their six opponents, a set of network metrics were computed. Data were calculated using Gephi software. There were an average of 745 (SD = 68) passes for each game constituting a total of 4,472 passes between players with an average of 373 (SD = 78) passes coded per team. Computations involved micro level of analysis related to player position centralities across the team, and macro levels of analysis related to the network of the team as a whole. The results showed that the backcourt players are the key players in the attack against the most used defences. Interestingly, a comparison of total passes per match against 6:0 defences and against 5:1 defences, for Pick and the opponent teams, showed that the total passes for Pick were only higher than their opponents in the match that Pick lost. The total passes against 6:0 formation were only higher for Pick in one match, and the total passes against 5:1 formations were higher for Pick in the matches that the team drew and lost. These results may indicate that passing network metrics can identify weaknesses of a team to particular defensive formations used by their opponents.

Use of head-mounted displays (HMDs) and hand-held displays (HHDs) may affect the effectiveness of stability control mechanisms and impair resistance to falls. This study aimed to examine whether the ability to control stability during locomotion is diminished while using HMDs and HHDs. Fourteen healthy adults (21–46 years) were assessed under single-task (no display) and dual-task (spatial 2-n-back presented on the HMD or the HHD) conditions while performing various locomotor tasks. An optical motion capture system and two force plates were used to assess locomotor stability using an inverted pendulum model. For perturbed standing, 57% of the participants were not able to maintain stability by counter-rotation actions when using either display, compared to the single-task condition. Furthermore, around 80% of participants (dual-task) compared to 50% (single-task) showed a negative margin of stability (i.e., an unstable body configuration) during recovery for perturbed walking due to a diminished ability to increase their base of support effectively. However, no evidence was found for HMDs or HHDs affecting stability during unperturbed locomotion. In conclusion, additional cognitive resources required for dual-tasking, using either display, are suggested to result in delayed response execution for perturbed standing and walking, consequently diminishing participants’ ability to use stability control mechanisms effectively and increasing the risk of falls.

For human locomotion, varying environments require adjustments of the motor system. We asked whether age affects gait balance recovery adaptation, its retention over months, and the transfer of adaptation to an untrained reactive balance task. Healthy adults (26 young, 27 middle-aged, and 25 older; average ages 24, 52, and 72 yr, respectively) completed two tasks. The primary task involved treadmill walking: either unperturbed (control; n = 39) or subject to unexpected trip perturbations (training; n = 39). A single trip perturbation was repeated after a 14-wk retention period. The secondary transfer task, before and after treadmill walking, involved sudden loss of balance in a lean-and-release protocol. For both tasks, the anteroposterior margin of stability (MoS) was calculated at foot touchdown. For the first (i.e., novel) trip, older adults required one more recovery step ( P = 0.03) to regain positive MoS compared with younger, but not middle-aged, adults. However, over several trip perturbations, all age groups increased their MoS for the first recovery step to a similar extent (up to 70%) and retained improvements over 14 wk, although a decay over time was found for older adults ( P = 0.002; middle-aged showing a tendency for decay: P = 0.076). Thus, although adaptability in reactive gait stability control remains effective across the adult life span, retention of adaptations over time appears diminished with aging. Despite these robust adaptations, the perturbation training group did not show superior improvements in the transfer task compared with age-matched controls (no differences in MoS changes), suggesting that generalizability of acquired fall-resisting skills from gait-perturbation training may be limited. NEW & NOTEWORTHY The human neuromotor system preserves its adaptability across the adult life span. However, although adaptability in reactive gait stability control remains effective as age increases, retention of recovery response adaptations over time appears to be reduced with aging. Furthermore, acquired fall-resisting skills from single-session perturbation training seem task specific, which may limit the generalizability of such training to the variety of real-life falls.

© 2018 Elsevier Ltd Perturbation training is an emerging approach to reduce fall risk in the elderly. This study examined potential differences in retention of improvements in reactive gait stability over 14 weeks resulting from unexpected trip-like gait perturbations. Twenty-four healthy middle-aged adults (41–62 years) were assigned randomly to either a single perturbation group (SINGLE, n = 9) or a group subjected to eight trip-like gait perturbations (MULTIPLE, n = 15). While participants walked on a treadmill a custom-built brake-and-release system was used to unexpectedly apply resistance during swing phase to the lower right limb via an ankle strap. The anteroposterior margin of stability (MoS) was calculated as the difference between the anterior boundary of the base of support and the extrapolated centre of mass at foot touchdown for the perturbed step and the first recovery step during the first and second (MULTIPLE group only) perturbation trials for the initial walking session and retention-test walking 14 weeks later. Group MULTIPLE retained the improvements in reactive gait stability to the perturbations (increased MoS at touchdown for perturbed and first recovery steps; p < 0.01). However, in group SINGLE no differences in MoS were detected after 14 weeks compared to the initial walking session. These findings provide evidence for the requirement of a threshold trip-perturbation dose if adaptive changes in the human neuromotor system over several months, aimed at the improvement in fall-resisting skills, are to occur.

Obstacle avoidance is one of the skills required in coping with challenging situations encountered during walking. This study examined adaptation in gait stability and its interlimb transfer in a virtual obstacle avoidance task. Twelve young adults walked on a treadmill while wearing a virtual reality headset with their body state represented in the virtual environment. At random times, but always at foot touchdown, 50 virtual obstacles of constant size appeared 0.8 m in front of the participant requiring a step over with the right leg. Early, mid and late adaptation phases were investigated by pooling data from trials 1-3, 24-26 and 48-50. One left-leg obstacle appearing after 50 right-leg trials was used to investigate interlimb transfer. Toe clearance and the anteroposterior margin of stability (MoS) at foot touchdown were calculated for the stepping leg. Toe clearance decreased over repeated practice between early and late phases from 0.13 ± 0.05 m to 0.09 ± 0.04 m (mean ± SD, p

Our understanding of health has changed substantially since the World Health Organization initially defined health in 1948 as “a state of complete physical, mental and social and well-being and not merely the absence of disease or infirmity”. These changes include reconceptualizing health on a continuum rather than as a static state, and adding existential health to physical, mental, and social well-being. Further, good health requires adaptation in coping with stress and is influenced by social, personal and environmental factors. Building on prior work, we propose a reconsidered 2020 definition: “Health is the dynamic balance of physical, mental, social, and existential well-being in adapting to conditions of life and the environment.” Health is dynamic, continuous, multidimensional, distinct from function, and determined by balance and adaptation. This new definition has implications for research, policies, and practice, with particular relevance for health considered within a context of disability and chronic conditions.

Rapid stepping to preserve stability is a crucial action in avoiding a fall. It is also an important measure in the assessment of fall-resisting skills. We examined whether volitional step execution correlates with recovery stepping performance after sudden balance loss for adults of different ages. In addition, we investigated whether volitional step performance can discriminate between individuals with high and low balance recovery capabilities, i.e. between those making single versus multiple steps after balance perturbation. Healthy adults (28 young, 43 middle-aged and 26 older; 24 ± 4, 52 ± 5 and 72 ± 5 years respectively) performed a single step in the anterior direction volitionally in response to a mechanical stimulus to the heel. In a second stepping task, participants experienced sudden anterior balance loss in a lean-and-release protocol. For both tasks, an optical motion capture system was used to assess stepping kinematics. We found on average 28% shorter reaction times, 46% faster maximal step velocities and 48% higher rates of increase in base of support across all participants after sudden balance loss compared to volitional stepping (p

Epoxy‐based layered silicate nanocomposites of various compositions were synthesized and their physical and water vapor diffusion properties studied. Mixtures of an epoxide monomer, diglycidyl ether of bisphenol A, with nonmodified sodium montmorillonite (NaMMT) or organophilically modified montmorillonites were prepared and cross‐polarized optical microscopy, oscillatory shear rheological measurements, transmission electron microscopy (TEM), and X‐ray diffraction (XRD) studies were used to assess epoxy intercalation in the intragallery regions of the layered silicates. The more hydrophilically modified organoclays showed a higher degree of compatibility with the epoxide monomer and a higher degree of intercalation and delamination of the silicate nanolayers, when compared to the mixtures containing NaMMT and highly hydrophobically modified organoclays. The epoxy‐clay mixtures were cured by the addition of a stoichiometric amount of an aliphatic polyoxypropylene diamine at 120°C. The curing reaction appea...

Individual dendritic branches can solubilise hydrophilic dyes in apolar media. The functional group at the focal point of the dendritic branch plays a key role in the dye uptake process. Supramolecular interactions between carboxylic acid and amine groups have been shown to be effective in enabling efficient solubilisation to occur. The necessary complementarity of this interaction is further illustrated by a series of control experiments. The extent of dendritic branching (i.e. dendritic generation) plays a key role in controlling the extent of dye uptake, with higher-generation dendritic branches exhibiting more efficient uptake at lower concentrations. UV/Visible spectroscopic methods have shown that the dendritic branches, in addition to the tuning of the extent of dye uptake, also tune the optical properties of the solubilised dye and this provides further insight into the interactions occurring between the solubilised dye and the individual dendritic branches. Furthermore, it is shown that suitably functionalised dendritic branches can transport hydrophilic dyes through an apolar phase and deliver them continuously into an aqueous medium.

In this paper we report the use of both in-situ solid-state H-1 and solid-state C-13 NMR to characterise the condensed-phase residues obtained upon the degradation under inert and oxidative conditions of urethane-modified polyisocyanurate foams based on polypropylene glycol (PPG) and 4,3'-diisocyanato diphenylenemethane (MDI). In particular, we examine the relationship between chain mobility and volatile loss and relate this to the flammability of these materials as characterised by limiting oxygen index (LOI) measurements. Differential scanning calorimetry (DSC), thermogravimetry (TGA) and pyrolysis experiments reveal that the biggest difference in the behaviour of the foams is under inert rather than oxidative conditions. It is thus concluded that the difference in the observed flammability of the samples derives from differences in the volatile release profiles upon degradation in an essentially inert environment. Both DSC and high temperature H-1 NMR results clearly indicate that there are two major scission processes occurring within the polymers. The lower temperature process is due to the scission of the urethane links, whilst a higher temperature process that becomes increasingly significant as the isocyanurate content of the polymer increases, is due to the scission of the isocyanurate linkages. In addition, C-13 NMR data on the residues clearly show that PPG is lost preferentially from those materials with the highest urethane:isocyanurate ratio. The different fire performance of the four foams under study here is thus ascribed to the conjunction of three factors, all associated with the evolution of PPG or PPG fragments. First, the lower thermal stability of the urethane links leads to facile depolymerisation to yield free PPG from those foams where urethane dominates over isocyanurate linkages. Second, the lower molar mass PPG from these foams is more volatile than that in the isocyanurate dominated foams. Third, the more rigid cross-linked network of the predominately isocyanurate linked foams restricts the diffusion of volatile species formed by and subsequent to the scission of any urethane bonds or the glycol backbone.

The aim of this investigation is to ascertain whether the mode of action of melamine in flexible polyurethane (PU) involves condensed phase chemistry in terms of promoting char formation. A combination of in situ 1HNMR analysis, solid state 13CNMR characterization of chars prepared ex situ, and normal TGA and DSC has been employed. Solid state 13CNMR indicates that there is no major discernible difference in the structure of the dichloromethane-insoluble chars prepared with and without melamine, the remaining polyol only accounting for 20-25% of the total carbon at 350°C, but still being quite mobile. However, in situ 1HNMR provides definitive evidence that melamine acts in the condensed phase in terms of promoting the formation of rigid char which forms in more significant quantity by 450°C. No increase in the residue yields is observed by TGA upon melamine addition, probably due to a combination of the small sample size and open sample holder in relation to the in situ 1HNMR analysis which also involves fairly slow heating.

The notation method reported in this paper was developed when one of the authors was working with a non-league football club. Matches were recorded using video but there was still a need for timelines of match events – set-pieces, attempts on goal and so forth. Some of the information sought by management (on passing sequences, for example) required more detailed notation. This aspiring junior club was no different from many others: resources were limited. Even if they had been inclined to purchase one of the pieces of sophisticated software used for modern notation, they would not have had the staff to operate it. The barcode scanning method reported here was developed with this type of club in mind but is flexible enough to be used for a wide variety of notational purposes, both for real-time coding and in working from video. 35.2 THE METHOD We have been using small, highly portable barcode scanners to make time-coded recordings of events in competitive sport, mainly football and taekwondo. In the case of football, recordings were made both in real-time and from video footage; for taekwondo, recordings were made solely from video. Competition records were tabulated, analysed and prepared for presentation using Excel software. The method operates in the following way:1 The sport events to be recorded are coded as short, abbreviated strings of characters.

THY-1, the smallest member of the immunoglobulin superfamily1, is a major cell-surface component expressed by several tissues2. The protein1carbohydrate3 and gene4 structures of this molecule are known, yet its function is not. It is highly expressed in nervous tissue5, where it appears on virtually all neurons after the cessation of axonal growth6. Here we show that expression of Thy-1 by a neural cell line inhibits neurite outgrowth on mature astrocytes, but not on other cellular substrata which include Schwann cells and embryonic glia. This inhibition of neurite extension on astrocytes can be reversed by low concentrations (nanomolar) of soluble Thy-1. If a similar interaction between neuronal Thy-1 and astrocytes occurs in vivo, it could stabilize neuronal connec-tions and suppress axonal regrowth after injury in the astrocyte-rich areas of adult central nervous system.

Generating polymers in the presence of a self-assembling gelator with terminal double bonds yields polymeric materials with embedded reactive nano-skeletons-subsequent washing gives nanoscale imprinted materials with fibrillar architectures.

Dissociated rat hippocampal neurons were cultured on horizontal cryostat sections from neonatal and adult rat brain and their growth patterns visualized by brightfield and interference contrast microscopy. Cells adhered to the sections as individuals or in small clusters and grew extensive neurites. Neurites grew over all areas of neonatal sections without apparent selectivity. For adult sections, however, neurites grew almost exclusively on areas of grey matter: there was no neurite growth on areas of white matter, irrespective of the location of that white matter within the brain. The transition from the neonatal to the adult pattern of growth occurred for sections from animals aged between 14 and 21 days.

ATP hydrolysis and proton translocation in chromaffin granules were followed using 31P nuclear magnetic resonance. The intragranular pH affects the resonance frequency of the gamma-phosphate of granular ATP. By measuring frequency vs. pH in solutions which simulate the intragranular matrix, this may be calibrated to give quantitative pH measurements. The pH in the resting granule is 5.65 +/- 0.15. This drops by 0.4 to 0.5 pH unit when ATP is added externally and protons are actively pumped into the granules. Because of differences in the composition and pH of the internal and external solutions, the resonances of internal and external nucleotides and Pi can be distinguished. Consequently, ATP hydrolysis and changes in internal pH may be observed simultaneously and continuously in a single sample of chromaffin granules. From the measured buffering capacity of a reconstituted intragranular solution, pH changes were converted into an absolute number of protons translocated. The net proton flux (protons translocated/ATP hydrolyzed) was about 1.0 immediately after external ATP addition but fell toward zero as the pH gradient increased to a new steady state. These 31P NMR results agree with intragranular pH measurements determined from methylamine distribution and with H+/ATP stoichiometries calculated from pH changes observed in the external medium.

Publisher Summary Chemical signals appear to play important roles in development of neural tissue. For example, they may function to spatially and temporally coordinate the differentiation of specific cell groups, to provide tropic signaling and guidance, and to mediate cell-cell communication and feedback. Moreover, because of their potential to function extracellularly, chemical signals could work either in restricted local environments, or, more diffusely, over long distances. Within the last 30 years, a number of macromolecular factors have been identified that can influence the development and differentiation of the nervous system. NGF is presently the most useful model available for studying the actions of chemical factors that regulate neural development. The aim of this chapter is to explore the role of the genome in the action of nerve growth factor.

Phosphorus nuclear magnetic resonance measurements at 129MHz have been made on small beating rat hearts, perfused by the Langendorff technique. Good spectra, giving the levels of ATP, creatine phosphate and inorganic phosphate can be collected in as little as 10–20min and the heart can be maintained in a steady state in the spectrometer for at least 5 hours. In a good preparation, the ratios of the β-phosphate of ATP to creatine phosphate and inorganic phosphate are 1:1.8:1.8 which compare well with the data obtained by analyzing a freeze-clamped extract by NMR. The recovery of metabolites, after the induction of global ischaemia, has been followed.

Nerve growth factor (NGF) has a variety of actions on its physiological targets, sympathetic and sensory neurons (Levi-Montalcini and Angeletti, 1968; Green and Shooter, 1980; Thoenen and Barde, 1980). Among the most striking of these actions is the promotion of neurite outgrowth. This chapter will focus on the mechanisms by which NGF causes neuritis to be initiated and maintained.

The electron spin resonance spectrum of rabbit muscle d -glyceraldehyde-3-phosphate dehydrogenase spin-labelled with 4-(2-iodoacetamido)-2,2,6,6-tetramethylpiperidinooxyl has two components. One component is due to a spin label highly immobilized on the enzyme surface and the other to a nitroxyl group able to tumble rapidly. The spin-labelled enzyme is inactive. Selective modification of the active site cysteine residue (149) and determinations of total sulphydryl content implicate this residue as the site of the immobile spin-label. The mobile spin label is attached to another sulphydryl group. Crystallographic studies on the human muscle enzyme (Watson, H.C., Duee, E. and Mercer, W.D. (1972) Nat. New Biol., 240, 130) have located a binding site for samarium ion in the active centre. Addition of the paramagnetic gadolinium ion to spin-labelled enzyme reduces the intensity of both the spin label signals (by 72% for the mobile and by 11% for the immobile component). This indicates that the metal ion site ( K d = 0.7 mM ) is close to both types of spin label. Measurements of the effect of gadolinium-protein binding on the relaxation rate of solvent water protons enable the enzyme-bound spin label-metal ion distances to be tentatively estimated as 15 A.

Nerve growth factor protein (NGF) was found to rapidly promote the activation of tyrosine hydroxylase in cultured rat PC 12 pheochromocytoma cells. PC 12 cultures were exposed to NGF for periods of less than 1 h and the soluble contents of homogenates prepared from the cells were assayed for tyrosine hydroxylase activity. Under these conditions, the specific enzymatic activity was increased by 60 ± 10% (n = 13) in comparison with that in untreated sister cultures. The increase was half maximal by 2–5 min of exposure and at NGF concentrations of about 10 ng/ml (0.36 nM). Antiserum against NGF blocked the effect. Tyrosine hydroxylase activity could also be rapidly increased by NGF in cultures of PC12 cells that had been treated with the factor for several weeks in order to produce a neuron-like phenotype. This was achieved by withdrawing NGF for about 4 h and then readding it for 30 min. The NGF-induced increase of tyrosine hydroxylase activity in PC12 cultures was not affected by inhibition of protein synthesis and therefore appeared to be due to activation of the enzyme. Kinetic experiments revealed that NGF brought about no change in the apparent Km of the enzyme for tyrosine or for co-factor (6-methyltetrahydropteridine), but that it did significantly increase the apparent maximum specific activity of the enzyme. These observations suggest that NGF (perhaps released by target organs) could promote a rapid and local enhancement of noradrenergic transmission in the sympathetic nervous system.

Publisher Summary This chapter elaborates the phosphorus nuclear magnetic resonance studies on perfused heart. 31P NMR can be used as a nondestructive method to follow the levels of phosphorus-containing metabolites, and to measure intracellular pH in intact tissues, and functioning organs. It is found that since the integrals of the individual phosphorus resonances depend on the total amount of the particular phosphate-compound present, the NMR method measures the quantities of tissue metabolites. The time required to collect good signals determines the time resolution of the method in kinetic experiments. One can determine creatine phosphate levels in about 1 min on a small rat or mouse heart, and the tissue pH in about 30 s. Comparison of the analytical data with that obtained from conventional freezing and extraction shows good agreement with accepted biochemical data. Measurements of tissue pH are also in good agreement with those obtained by other methods. NMR spectra contain additional information about the mobility, binding, and interaction of metabolites with other cellular components.