Kinematic characteristics of barefoot sprinting in habitually shod children

Background. Anecdotally, a wide variety of benefits of barefoot running have been advocated by numerous individuals. The influence of the alterations in the properties of the shoe on the running movement has been demonstrated in adults at submaximal jogging speeds. However, the biomechanical differences between shod and barefoot running in children at sprinting speeds and the potential developmental implications of these differences are still less examined. The purpose was to determine the potential differences in habitually shod children's sprint kinematics between shod and barefoot conditions. Methods. Ninety-four children (51 boys and 43 girls; 6-12 years-old; height, 135.0 ± 0.12 m; body mass, 29.0 ± 6.9 kg) performed 30 m maximal sprints from standing position for each of two conditions (shod and barefoot). To analyze sprint kinematics within sagittal plane sprint kinematics, a high-speed camera (300 fps) was set perpendicular to the runway. In addition, sagittal foot landing and take-offimages were recorded for multiple angles by using five high-speed cameras (300 fps). Spatiotemporal variables, the kinematics of the right leg (support leg) and the left leg (recovery leg), and foot strike patterns: rear-foot strike (RFS), mid-foot strike (MFS), and forefoot strike (FFS) were investigated. The paired t -test was used to test difference between shod and barefoot condition. Results. Barefoot sprinting in habitually shod children was mainly characterized by significantly lower sprint speed, higher step frequency, shorter step length and stance time. In shod running, 82% of children showed RFS, whereas it decreased to 29% in barefoot condition. The touch down state and the subsequent joint movements of both support and recovery legs during stance phase were significantly altered when running in condition with barefoot. Discussion. The acute effects of barefoot sprinting was demonstrated by significantly slower sprinting speeds that appear to reflect changes in a variety of spatiotemporal parameters as well as lower limb kinematics. It is currently unknown whether such differences would be observed in children who typically run in bare feet and what developmental benefits and risks may emerge from increasing the proportion of barefoot running and sprinting in children. Future research should therefore investigate potential benefits that barefoot sprinting may have on the development of key physical fitness such as nerve conduction velocity, muscular speed, power, and sprinting technique and on ways to minimize the risk of any acute or chronic injuries associated with this activity. © 2018 Mizushima et al

Welcome to Molecular Brain

We are delighted to announce the arrival of a brand new journal dedicated to the ever-expanding field of neuroscience. Molecular Brain is a peer-reviewed, open-access online journal that aims at publishing high quality articles as rapidly as possible. The journal will cover a broad spectrum of neuroscience ranging from molecular/cellular to behavioral/cognitive neuroscience and from basic to clinical research. Molecular Brain will publish not only research articles, but also methodology articles, editorials, reviews, and short reports. It will be a premier platform for neuroscientists to exchange their ideas with researchers from around the world to help improve our understanding of the molecular mechanisms of the brain and mind

Low threshold quantum dot lasers directly grown on unpatterned quasi-nominal (001) Si

We report electrically pumped, continuous-wave (cw) InAs/GaAs quantum dot (QD) lasers directly grown on quasi-nominal Si (001) substrates with offcut angle as small as 0.4°. No GaP, Ge buffer layers or substrate patterning is required. An anti-phase boundary free epitaxial GaAs film was grown by metal-organic chemical vapor deposition (MOCVD) with a low threading dislocation density of ${3\times 10^{7} {\rm{cm^{-2}}}}$ . Room-temperature cw lasing at ∼1.3 μm has been achieved, with a minimum threshold current density of 34.6 A/cm2 per layer, a maximum operating temperature of 80 °C, and a maximum single facet output power of 52 mW. A comparison of various monolithic III-V hetero-epitaxy on Si solutions is presented. Direct growth on unpatterned quasi-nominal (001) Si may yield the best material quality at the lowest lifecycle cost

Defect characterization of InAs/InGaAs quantum dot p-i-n photodetector grown on GaAs-on-V-grooved-Si substrate

The performance of semiconductor devices on silicon can be severely degraded by the presence of dislocations incurred during heteroepitaxial growth. Here, the physics of the defect mechanisms, characterization of epitaxial structures, and device properties of waveguide photodetectors (PDs) epitaxially grown on (001) Si are presented. A special GaAs-on-V-grooved-Si template was prepared by combining the aspect ratio trapping effects, superlattice cyclic, and strain-balancing layer stacks. A high quality of buffer structure was characterized by atomic force microscopy (AFM) and electron channeling contrast imaging (ECCI) results. An ultralow dark current density of 3.5 × 10–7A/cm2 at 300 K was measured under −1 V. That is 40× smaller than the best reported value of epitaxially grown InAs/GaAs quantum dot photodetector structure on GaP/Si substrate. Low frequency noise spectroscopy was used to characterize the generation and recombination related deep levels. A trap with an activation energy of 0.4 eV was identified, which is near the middle bandgap. With low frequency noise spectroscopy along with the current–voltage and capacitance–voltage characterizations, the recombination lifetime of 27 μs and trap density of 5.4 × 1012 cm–3 were estimated

Mindfulness-based cognitive therapy v. group psychoeducation for people with generalised anxiety disorder: randomised controlled trial

Background: Research suggests that an 8-week mindfulness-based cognitive therapy (MBCT) course may be effective for generalised anxiety disorder (GAD). Aims: To compare changes in anxiety levels among participants with GAD randomly assigned to MBCT, cognitive–behavioural therapy-based psychoeducation and usual care. Method: In total, 182 participants with GAD were recruited (trial registration number: CUHK_CCT00267) and assigned to the three groups and followed for 5 months after baseline assessment with the two intervention groups followed for an additional 6 months. Primary outcomes were anxiety and worry levels. Results: Linear mixed models demonstrated significant group × time interaction (F(4,148) = 5.10, P = 0.001) effects for decreased anxiety for both the intervention groups relative to usual care. Significant group × time interaction effects were observed for worry and depressive symptoms and mental health-related quality of life for the psychoeducation group only. Conclusions: These results suggest that both of the interventions appear to be superior to usual care for the reduction of anxiety symptoms

Electrically pumped continuous wave quantum dot lasers epitaxially grown on patterned, on-axis (001) Si

High performance III-V lasers at datacom and telecom wavelengths on on-axis (001) Si are needed for scalable datacenter interconnect technologies. We demonstrate electrically injected quantum dot lasers grown on on-axis (001) Si patterned with {111} v-grooves lying in the [110] direction. No additional Ge buffers or substrate miscut was used. The active region consists of five InAs/InGaAs dot-in-a-well layers. We achieve continuous wave lasing with thresholds as low as 36 mA and operation up to 80°C

1.3 μm submilliamp threshold quantum dot micro-lasers on Si

As a promising integration platform, silicon photonics need on-chip laser sources that dramatically improve capability, while trimming size and power dissipation in a cost-effective way for volume manufacturability. Currently, direct heteroepitaxial growth of III–V laser structures on Si using quantum dots as the active region is a vibrant field of research, with the potential to demonstrate low-cost, high-yield, long-lifetime, and high-temperature devices. Ongoing work is being conducted to reduce the power consumption, maximize the operating temperature, and switch from miscut Si substrates toward the so-called exact (001) Si substrates that are standard in microelectronics fabrication. Here, we demonstrate record-small electrically pumped micro-lasers epitaxially grown on industry standard (001) silicon substrates. Continuous-wave lasing up to 100°C was demonstrated at 1.3 μm communication wavelength. A submilliamp threshold of 0.6 mA was achieved for a micro-laser with a radius of 5 μm. The thresholds and footprints are orders of magnitude smaller than those previously reported lasers epitaxially grown on Si