Magneto-Excitons in (411)A and (100)-Oriented GaAs/AlGaAs Multiple Quantum Well Structures

We report magneto-exciton spectroscopy studies of (411)A and (100)-oriented GaAs/Al{sub 0.3}Ga{sub 0.7}As multiquantum well structures. The samples consisted of seven GaAs quantum wells with widths varying between 0.6 and 12nm, were grown on (411)A and (100)-oriented GaAs substrates. The exciton diamagnetic energy shifts and linewidths were measured between 0 and 14T at 1.4K The dependence of the exciton diamagnetic shifts with magnetic field were calculated using a variational approach and good agreement with experiment for both substrate orientations was found

Physical activity to improve cognition in older adults: can physical activity programs enriched with cognitive challenges enhance the effects? A systematic review and meta-analysis

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Effectiveness of dual-task functional power training for preventing falls in older people: Study protocol for a cluster randomised controlled trial

Background: Falls are a major public health concern with at least one third of people aged 65 years and over falling at least once per year, and half of these will fall repeatedly, which can lead to injury, pain, loss of function and independence, reduced quality of life and even death. Although the causes of falls are varied and complex, the age-related loss in muscle power has emerged as a useful predictor of disability and falls in older people. In this population, the requirements to produce explosive and rapid movements often occurs whilst simultaneously performing other attention-demanding cognitive or motor tasks, such as walking while talking or carrying an object. The primary aim of this study is to determine whether dual-task functional power training (DT-FPT) can reduce the rate of falls in community-dwelling older people. Methods/Design: The study design is an 18-month cluster randomised controlled trial in which 280 adults aged =65 years residing in retirement villages, who are at increased risk of falling, will be randomly allocated to: 1) an exercise programme involving DT-FPT, or 2) a usual care control group. The intervention is divided into 3 distinct phases: 6 months of supervised DT-FPT, a 6-month 'step down' maintenance programme, and a 6-month follow-up. The primary outcome will be the number of falls after 6, 12 and 18 months. Secondary outcomes will include: lower extremity muscle power and strength, grip strength, functional assessments of gait, reaction time and dynamic balance under single- and dual-task conditions, activities of daily living, quality of life, cognitive function and falls-related self-efficacy. We will also evaluate the cost-effectiveness of the programme for preventing falls. Discussion: The study offers a novel approach that may guide the development and implementation of future community-based falls prevention programmes that specifically focus on optimising muscle power and dual-task performance to reduce falls risk under 'real life' conditions in older adults. In addition, the 'step down' programme will provide new information about the efficacy of a less intensive maintenance programme for reducing the risk of falls over an extended period. Trial registration: Australian New Zealand Clinical Trials Registry: ACTRN12613001161718. Date registered 23 October 2013

Ultra-short T-shaped gate fabrication technique for InP based HEMTs with high ft (> 300 GHz) and their MMIC applications

A fabrication technique for sub-50-nm T-shaped-gate InGaAs/InAlAs high electron mobility transistors (HEMTs) lattice-matched to InP substrates and their device characteristics are presented. A 35-nm T-shaped-gate HEMT is successfully fabricated by optimizing conditions of electron beam (EB) lithography and reactive ion etching (RIE) to make an ultra-fine resist pattern and precisely replicate it on a SiO2 film, which defines gate length (Lg). The device exhibits an excellent current-gain cutoff frequency (fT) as high as 317 GHz with high controllability. This technique is considered to be very effective for device and MMIC applications in the V band and even higher frequency ranges