Experimental determination of the Rashba coefficient in InSb/InAlSb quantum wells at zero magnetic field and elevated temperatures.

We report the optical measurement of the spin dynamics at elevated temperatures and in zero magnetic field for two types of degenerately doped n-InSb quantum wells (QWs), one asymmetric (sample A) and one symmetric (sample B) with regards to the electrostatic potential across the QW. Making use of three directly determined experimental parameters: the spin lifetime, τ(s), the sheet carrier concentration, n, and the electron mobility, µ, we directly extract the zero-field spin splitting. For the asymmetric sample where the Rashba interaction is the dominant source of spin splitting, we deduce a room temperature Rashba parameter of α = 0.09 ± 0.1 eV Å which is in good agreement with calculations and we estimate the Rashba coefficient α(0) (a figure of merit for the ease with which electron spins can be modulated via an electric field). We review the merits/limitations of this approach and the implications of our findings for spintronic devices.

Effectiveness of a balance training home exercise programme for adults with haemophilia: a pilot study.

Adults with haemophilia and other bleeding disorders often develop lower limb musculoskeletal problems associated with bleeds into joints and muscles, which may affect balance performance and increase likelihood of falling. The aim of this study was to evaluate the effectiveness of an individualized balance and strength home exercise programme on improving balance and related outcomes for adults with haemophilia and other bleeding disorders. Twenty male adults with haemophilia and other bleeding disorders (mean age 39.4 years, 95% CI = 33.7-45.1) were recruited to participate. They underwent a comprehensive clinical and force platform assessment of balance and related measures. Based on assessment findings, the assessing physiotherapist provided an individualized home exercise programme of balance, strengthening and walking exercises. Re-assessment occurred after the 4-month exercise programme. Twelve participants (60%) completed the programme and were re-assessed. There were no safety problems or dropouts associated with the exercise programme aggravating joint status. Although there were no statistically significant changes in any of the measures (adjusted for multiple comparisons), there were improvements of between 5% and 22% on 10 of the 16 measures, with the Neurocom modified Clinical Test of Sensory Interaction on Balance (P = 0.036) and Timed Sit to Stand (P = 0.064) approaching significance. A tailored home exercise programme targeting balance, strengthening and walking is feasible for adults with haemophilia and other bleeding disorders. These results suggest that positive physical outcomes including improved balance and mobility may be achieved with this type of programme.

Balance dysfunction in adults with haemophilia.

The main focus of lower limb physical performance assessment in people with haemophilia (PWH) has usually been on function, muscle strength and joint flexibility. The impact of haemophilic arthropathy on balance and falls risk is relatively under-explored. The aim of this study was to evaluate balance and related performance in PWH compared with age and gender matched healthy controls. It involved a comprehensive suite of clinical and laboratory measures of static and dynamic balance, mobility, strength, physical activity and falls efficacy completed in 20 PWH (mean age 39.4, 100% male) and 20 controls. Fifty percent of PWH reported falls in the past 12 months. Moderate impairment of balance and related measures were identified in PWH compared with the controls, with an average 35% difference between groups. Significant differences were evident between groups on both clinical and laboratory measures, including measures of dynamic bilateral stance balance [limits of stability measures on the laboratory test, functional reach; (P < 0.001); dynamic single leg balance (Step Test, P < 0.001)], gait and mobility (gait speed, step width and turning measures on the laboratory test, timed up and go test; P < 0.001); muscle strength (timed sit to stand, P = 0.002; quadriceps strength, P < 0.001); and activity level and falls efficacy, (P < 0.004). The dynamic clinical and laboratory measures testing similar domains of balance, gait and mobility had moderate correlations (0.310 < r < 0.531, P < 0.01). Moderate impairments in balance, mobility and related measures were identified in PWH, compared with the control group. Clinicians should include assessments of balance and related measures when reviewing adults with haemophilia.

Room temperature ballistic transport in InSb quantum well nanodevices.

We report the room temperature observation of significant ballistic electron transport in shallow etched four-terminal mesoscopic devices fabricated on an InSb/AlInSb quantum well (QW) heterostructure with a crucial partitioned growth-buffer scheme. Ballistic electron transport is evidenced by a negative bend resistance signature which is quite clearly observed at 295 K and at current densities in excess of 10(6) A/cm(2). This demonstrates unequivocally that by using effective growth and processing strategies, room temperature ballistic effects can be exploited in InSb/AlInSb QWs at practical device dimensions.

Sub-100-nm negative bend resistance ballistic sensors for high spatial resolution magnetic field detection.

We report the magnetic field detection properties of ballistic sensors utilizing the negative bend resistance of InSb∕In(1-x)Al(x)Sb quantum well cross junctions as a function of temperature and geometric size. We demonstrate that the maximum responsivity to magnetic field and its linearity increase as the critical device dimension is reduced. This observation deviates from the predictions of the classical billiard ball model unless significant diffuse boundary scattering is included. The smallest device studied has an active sensor area of 35×35 nm(2), with a maximum responsivity of 20 kΩ∕T, and a noise-equivalent field of 0.87µT∕Hz at 100 K.