Enhanced noise at high bias in atomic-scale Au break junctions

Heating in nanoscale systems driven out of equilibrium is of fundamental importance, has ramifications for technological applications, and is a challenge to characterize experimentally. Prior experiments using nanoscale junctions have largely focused on heating of ionic degrees of freedom, while heating of the electrons has been mostly neglected. We report measurements in atomic-scale Au break junctions, in which the bias-driven component of the current noise is used as a probe of the electronic distribution. At low biases ($<$ 150~mV) the noise is consistent with expectations of shot noise at a fixed electronic temperature. At higher biases, a nonlinear dependence of the noise power is observed. We consider candidate mechanisms for this increase, including flicker noise (due to ionic motion), heating of the bulk electrodes, nonequilibrium electron-phonon effects, and local heating of the electronic distribution impinging on the ballistic junction. We find that flicker noise and bulk heating are quantitatively unlikely to explain the observations. We discuss the implications of these observations for other nanoscale systems, and experimental tests to distinguish vibrational and electron interaction mechanisms for the enhanced noise.Comment: 30 pages, 7 figure

The provision of simple written material does not significantly improve physical activity rates in a population with musculoskeletal problems, a double-blinded randomised controlled trial

BACKGROUND: Physical activity has been shown to have significant health benefits to individuals, being effective in the treatment and prevention of multiple different conditions. However, despite these benefits, rates of physical activity remain low in the western world and less than 40% of people in the UK meet physical activity recommendations. Musculoskeletal pain can be a barrier to activity, and patients with pain can stop all activity out of fear of harm. This project seeks to see if simple written advice can influence activity rates and behaviours. METHODS: A double-blinded randomised controlled trial was conducted to assess any impact of simple written material on physical activity rates in patients attending a single UK National Health Service (NHS) Sports Medicine Department. 546 consecutive patients with a range of musculoskeletal problems were randomised to either an “intervention group” (n=235) or “control group” (n=311). Patients in the intervention group received simple written material encouraging of the benefits of physical activity for general aspects of health, including practical steps to increase regular activity in daily life such as commuting, and work. RESULTS: No significant difference in activity rates were seen between the members of the two groups in any of the outcome measures used. These measures included the short-form/7-day recall version of the International Physical Activity Questionnaire (IPAQ), the General Practitioner Physical Activity Questionnaire (GPPAQ), and the “Vital Signs” questions. There were no differences seen in transport choices. Overall physical activity levels were low among both groups, with only one-third reaching national targets of 150minutes of moderate-level physical activity per week, and one in five patients undertaking no regular physical activity. CONCLUSIONS: The provision of simple written material does not significantly improve physical activity rates in patients referred to this NHS Sports Medicine Clinic in the UK. Consideration must be given to more tailored and individualised approached to physical activity promotion

The addition of a tension night splint to a structured home rehabilitation programme in patients with chronic plantar fasciitis does not lead to significant additional benefits in either pain, function or flexibility: a single-blinded randomised controlled trial

Objective To identify any improvements in pain or function in patients with chronic plantar fasciitis following the use of a tension night splint (TNS). Methods Single-blinded randomised controlled trial, with participants split evenly between intervention group (TNS + home exercise programme/HEP) and control group (HEP only). Follow-up at 3 months, with interim data at 6 weeks. Results 40 patients recruited. Mean age 52.1 years, 33% male, mean body mass index 30.8 kg/m2, mean duration of symptoms of 25 months. Improvement in self-reported ‘average pain’ in the intervention group from 6.8/10 at baseline to 5.6/10 at 6 weeks, and 5.3/10 at 3 months (both clinically and statistically significant at both time points), compared with control group of 7.1/10 at baseline to 6.2/10 at 6 weeks and 5.6/10 at 3 months (significant only at 3 months). Improvements in self-reported ‘worst pain’, ‘pain walking’ and ‘pain first thing in the morning’ in both groups at all time periods. Improvements were seen in revised Foot Function Index at all time points in both groups, but limited changes seen in flexibility and no significant changes in anxiety or depression Hospital Anxiety and Depression Scale domains or sleep quality in either group. However, no differences were seen between the outcomes seen in the two groups for the majority of the measures studied. Conclusions Improvements in pain and some functional measures seen in both groups, with few, if any, differences seen in outcomes between the intervention group compared with the control group. However, ongoing pain symptoms were reported in both groups, suggesting that ‘help’ rather than ‘cure’ was obtained for the majority. There is a possibility of earlier benefit seen in the intervention group compared with the control group, but data are unclear and further work may be needed

Extracorporeal shock wave therapy plus rehabilitation for insertional and noninsertional achilles tendinopathy shows good results across a range of domains of function

Achilles tendinopathy, both insertional and noninsertional, is a common cause of posterior ankle pain. Although the condition of most patients improves with simple conservative measures, a proportion will go on develop chronic symptoms. This study examines the outcomes of patients following extracorporeal shock wave therapy plus a home exercise program. This prospective case series study involves a total of 39 patients, with a mean follow-up duration of 163 (range 65 to 385) days. This has demonstrated significant benefits in pain, stiffness, and a range of measures of local and global function. Median (interquartile range [IQR]) values for average self-reported pain improved from 6.5 of 10 (IQR 5.0 to 7.8) at baseline to 3.5 of 10 (IQR 2.0 to 5.1) at 3 months and to 2.0 of 10 (IQR 0.6 to 4.8) at 6 months for patients with insertional Achilles tendinopathy. This compares to improvements from 7.0 of 10 (IQR 7.0 to 8.0) at baseline to 6.0 of 10 (IQR 5.6 to 6.8) at 3 months and to 6.0 of 10 (IQR 3.0 to 7.0) at 6 months for patients with noninsertional Achilles tendinopathy. Statistically significant improvements were seen in insertional tendinopathy across a range of outcome measures; however, these were less apparent for patients with noninsertional tendinopathy. Despite these figures, no significant differences were seen in the outcomes for patients with insertional and noninsertional tendinopathy. Despite the improvements seen in the aspects of pain and function, physical activity levels had not increased following the treatment

Up to a quarter of patients with certain chronic recalcitrant tendinopathies may have central sensitisation: a prospective cohort of more than 300 patients

Introduction: To identify the possible prevalence of ‘central sensitisation’, in patients with chronic recalcitrant lower limb tendinopathy conditions, with the Central Sensitisation Inventory (CSI) questionnaire. Methods: Patients with chronic lower limb tendinopathy conditions treated within a single hospital outpatient clinic specialising in tendinopathy were identified from clinical records. As part of routine care, self-reported numerical markers of pain, global function (using the EuroQol-5D (EQ-5D) questionnaire) and the CSI score to investigate the possibility of central sensitisation were completed. Results: A total of 312 suitable patients with chronic lower limb tendinopathy and similar conditions were identified, who had completed a CSI questionnaire. Of these, 108 presented with greater trochanteric pain syndrome, 12 with patella tendinopathy, 33 with non-insertional Achilles tendinopathy, 48 with insertional Achilles tendinopathy and 110 with plantar fasciitis. A total of 66% of the patients were female, the median age was 54.9 years and the median duration of symptoms was 24 months. There was a median CSI score of 25%, with statistically significant differences noted between the different conditions studied. Overall, 20% of patients scored above a threshold of 40% on CSI questionnaire, indicating that central sensitisation was possible. Greater trochanteric pain syndrome and plantar fasciitis had the highest proportions in the conditions studied. Weak correlations were found between CSI and other pain scores studied. Conclusion: The CSI questionnaire may identify up to a quarter of patients with some chronic lower limb tendinopathy and associated conditions as being more likely to have central sensitisation, and these proportions differed between conditions. The clinical significance of this is unclear, but worth further study to see if/how this may relate to treatment outcomes. These are results from a single hospital clinic dealing with patients with chronic tendinopathy, and comparison with a control group is currently lacking. However, on the information presented here, the concept of central sensitisation should be considered in patients being treated for chronic tendinopathy

Electrical braking in matrix converter for more electric aircraft: bi-directional switch and input power clamp methods

Current aircraft power quality specifications do not allow regeneration onto the power bus. Therefore, the inherent regeneration available from Matrix Converter (MC) is not desirable in More Electric Aircraft (MEA) aerospace applications. In this paper, novel methods to avoid regeneration from the Matrix Converters are proposed. The methods have been called the Bi-Directional Switch (BDS) method and the Input Power Clamp (IPC) method. Both methods are compared. The IPC method is considered an alternative to the Bi-Directional Switch (BDS) method and has a number of advantages discussed in the paper. To detect regeneration in Matrix Converters two techniques are proposed, the Power Comparison technique (PC) and the Input Voltage Reference technique (IVR). Experimental results from a prototype using 4 kW Induction Motor are presented

Matrix Converter for More Electric Aircraft

This proposed chapter discusses three methods that do not allow regenerative power from the matrix converter (MC) motor drive onto the aircraft power supply. According to aerospace power quality specifications, the regenerative power must be dissipated in the drive itself to avoid instability problem in aircraft power supply. These are bidirectional switch (BDS) method, input power clamp (IPC) method, and standard clamp circuit (SCC) method for aerospace applications. To identify regeneration in a matrix converter drive, two novel techniques are proposed. These are power comparison technique (PC) and input voltage reference technique (IVR). In both techniques, output power of MC and direction of speed, these factors are used to detect regeneration in MC drive. The electrical braking is important in many aerospace applications such as surface actuation and air-to-air (in-flight) refueling system. Therefore, the inherent regeneration capability of the matrix converter drive is not desirable for aerospace applications so it has to be avoided. The proposed methods are demonstrated through detailed simulation results and experimental verification. In order to prove the proposed methods with novel techniques, a 7.5-kW matrix converter fed 4-kW induction motor (IM) with inertial load has experimentally implemented. The obtained results using BDS method with PC technique proved avoiding regeneration with a matrix converter is feasible. This chapter is valuable for 150-kVA matrix converter for high-power application

A more efficient current source inverter with series connected AC capacitors for photovoltaic and fuel cell applications

Renewable energy sources such as photovoltaics (PVs) or fuel cells (FCs) are not fitted for direct power grid connection because they deliver DC voltage and current. In addition, they also have a high internal resistance/nonlinear V/I dependence, which is why a power electronic interface is always needed. This paper presents the implementation of a three-phase power electronic interface for PV/FCs that uses a single conversion stage approach based on a current source inverter (CSI) topology with series connected capacitors, that would need only six reverse blocking IGBTs and due to the possibility to reduce the AC voltage at high load, would reduce the size of magnetics and the losses compared to a standard CSI