Nanoantenna-enhanced ultrafast nonlinear spectroscopy of a single gold nanoparticle

Optical nanoantennas are a novel tool to investigate previously unattainable dimensions in the nanocosmos. Just like their radio-frequency equivalents, nanoantennas enhance the light-matter interaction in their feed gap. Antenna enhancement of small signals promises to open a new regime in linear and nonlinear spectroscopy on the nanoscale. Without antennas especially the nonlinear spectroscopy of single nanoobjects is very demanding. Here, we present for the first time antenna-enhanced ultrafast nonlinear optical spectroscopy. In particular, we utilize the antenna to determine the nonlinear transient absorption signal of a single gold nanoparticle caused by mechanical breathing oscillations. We increase the signal amplitude by an order of magnitude which is in good agreement with our analytical and numerical models. Our method will find applications in linear and nonlinear spectroscopy of nanoobjects, ranging from single protein binding events via nonlinear tensor elements to the limits of continuum mechanics

Abdominal functional electrical stimulation to improve respiratory function after spinal cord injury: a systematic review and meta-analysis

Objectives: Abdominal functional electrical stimulation (abdominal FES) is the application of a train of electrical pulses to the abdominal muscles, causing them to contract. Abdominal FES has been used as a neuroprosthesis to acutely augment respiratory function and as a rehabilitation tool to achieve a chronic increase in respiratory function after abdominal FES training, primarily focusing on patients with spinal cord injury (SCI). This study aimed to review the evidence surrounding the use of abdominal FES to improve respiratory function in both an acute and chronic manner after SCI. Settings: A systematic search was performed on PubMed, with studies included if they applied abdominal FES to improve respiratory function in patients with SCI. Methods: Fourteen studies met the inclusion criteria (10 acute and 4 chronic). Low participant numbers and heterogeneity across studies reduced the power of the meta-analysis. Despite this, abdominal FES was found to cause a significant acute improvement in cough peak flow, whereas forced exhaled volume in 1 s approached significance. A significant chronic increase in unassisted vital capacity, forced vital capacity and peak expiratory flow was found after abdominal FES training compared with baseline. Conclusions: This systematic review suggests that abdominal FES is an effective technique for improving respiratory function in both an acute and chronic manner after SCI. However, further randomised controlled trials, with larger participant numbers and standardised protocols, are needed to fully establish the clinical efficacy of this technique

Patient-Centered Research: Effects of Exercise and Testosterone Replacement Therapy on Elderly Males with Osteoarthritis and Hypogonadism

PURPOSE: Osteoarthritis commonly causes activity limitations in the elderly. Furthermore, males over 50 yr have an increased frequency of hypogonadism. The purpose of this 2 yr randomized trial is to determine the impact of PoleStriding(walking with poles in a motion similar to cross-country skiing) on elderly males (age = 71.0 ± 4.9 yr) with OA of the hip and/or knee and hypogonadism (testosterone = 198.3 ± 55.9 mg/ml) on measures of aerobic capacity, muscle strength, perceived pain and quality of life. METHODS: Eighteen subjects were randomized into a PoleStriding(PS) or an education (ED) group. All subjects received testosterone replacement therapy (200mg/ml IM biweekly). At baseline, 2, 4 and 6 months subjects completed the following tests: symptom-limited treadmill, upper and lower extremity strength, body composition, and range of motion. Measures of self-reported disability and perceived leg pain were also made at these periods. Subjects' pain and difficulty with ADLs was measured every 3 months using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). RESULTS: The results are based on data collected from 9 subjects at baseline and four months. Measures of strength did not change in either group. BMI increased by 2.7% in the ED group while the PS group showed no change. Subjects from both groups increased their exercise duration and aerobic capacity. The primary effect of the exercise is the markedly greater decrease in perceived pain during exertion after PoleStriding training. This finding is further supported by the WOMAC survey results. The PS group showed a 16% decrease in their overall WOMAC score indicating less pain, improved ability to perform ADLs and increased joint flexion; whereas the ED group showed a 28% increase in the overall WOMAC score indicating more pain, greater difficulty in performing ADLs, and decreased joint flexion. CONCLUSION: Testosterone therapy a had similar influence on exertional tolerance in the PS and ED group. However, the PS group reported greater reduction in perceived pain during exercise and ADLs. There may be a synergistic benefit of testosterone therapy and moderate intensity exercise in improving reserve capacity for performing ADLs

Estimation of Spectral Exponent Parameter of 1/f Process in Additive White Background Noise

An extension to the wavelet-based method for the estimation of the spectral exponent, γ, in a 1/fγ process and in the presence of additive white noise is proposed. The approach is based on eliminating the effect of white noise by a simple difference operation constructed on the wavelet spectrum. The γ parameter is estimated as the slope of a linear function. It is shown by simulations that the proposed method gives reliable results. Global positioning system (GPS) time-series noise is analyzed and the results provide experimental verification of the proposed method