Probing the charge of a quantum dot with a nanomechanical resonator

We have used the mechanical motion of a carbon nanotube (CNT) as a probe of the average charge on a quantum dot. Variations of the resonance frequency and the quality factor are determined by the change in average charge on the quantum dot during a mechanical oscillation. The average charge, in turn, is influenced by the gate voltage, the bias voltage, and the tunnel rates of the barriers to the leads. At bias voltages that exceed the broadening due to tunnel coupling, the resonance frequency and quality factor show a double dip as a function of gate voltage. We find that increasing the current flowing through the CNT at the Coulomb peak does not increase the damping, but in fact decreases damping. Using a model with energy-dependent tunnel rates, we obtain quantitative agreement between the experimental observations and the model. We theoretically compare different contributions to the single-electron induced nonlinearity, and show that only one term is significant for both the Duffing parameter and the mode coupling parameter. We also present additional measurements which support the model we develop: Tuning the tunnel barriers of the quantum dot to the leads gives a 200-fold decrease of the quality factor. Single-electron tunneling through an excited state of the CNT quantum dot also changes the average charge on the quantum dot, bringing about a decrease in the resonance frequency. In the Fabry-P\'{e}rot regime, the absence of charge quantization results in a spring behaviour without resonance frequency dips, which could be used, for example, to probe the transition from quantized to continuous charge with a nanomechanical resonator.Comment: 17 pages, 12 figure

A cohort evaluation on arterial stiffness and hypertensive disorders in pregnancy

10.1186/1471-2393-12-160BMC Pregnancy and Childbirth12-BPCM

STRIDER (Sildenafil TheRapy in dismal prognosis early onset fetal growth restriction): An international consortium of randomised placebo-controlled trials

Background: Severe, early-onset fetal growth restriction due to placental insufficiency is associated with a high risk of perinatal mortality and morbidity with long-lasting sequelae. Placental insufficiency is the result of abnormal formation and function of the placenta with inadequate remodelling of the maternal spiral arteries. There is currently no effective therapy available. Some evidence suggests sildenafil citrate may improve uteroplacental blood flow, fetal growth, and meaningful infant outcomes. The objective of the Sildenafil TheRapy In Dismal prognosis Early onset fetal growth Restriction (STRIDER) collaboration is to evaluate the effectiveness of sildenafil versus placebo in achieving healthy perinatal survival through the conduct of randomised clinical trials and systematic review including individual patient data meta-analysis.  Methods: Five national/bi-national multicentre randomised placebo-controlled trials have been launched. Women with a singleton pregnancy between 18 and 30 weeks with severe fetal growth restriction of likely placental origin, and where the likelihood of perinatal death/severe morbidity is estimated to be significant are included. Participants will receive either sildenafil 25 mg or matching placebo tablets orally three times daily from recruitment to 32 weeks gestation.  Discussion: The STRIDER trials were conceived and designed through international collaboration. Although the individual trials have different primary outcomes for reasons of sample size and feasibility, all trials will collect a standard set of outcomes including survival without severe neonatal morbidity at time of hospital discharge. This is a summary of all the STRIDER trial protocols and provides an example of a prospectively planned international clinical research collaboration. All five individual trials will contribute to a pre-planned systematic review of the topic including individual patient data meta-analysis

mental health and well-being in sedentary adults: A pilot study

Objectives: Physical activity has a positive effect on people's mental health and well-being. The aim of this study was to compare the effects of hatha yoga and resistance exercises on mental health and well-being in sedentary adults.Design: Randomized controlled study.Methods: Fifty-one participants aged mean (SD) 25.6 (5.7) years were randomly divided into three groups: Hatha Yoga Group, Resistance Exercise Group and Control Group. The Hatha Yoga Group and Resistance Exercise Group participated in sessions three days per week for 7 weeks and the Control Group did not participate in any sessions. All the subjects were evaluated through the Rosenberg Self-Esteem Scale, Beck Depression Inventory, Body Cathexis Scale, Nottingham Health Profile and Visual Analog Scale for fatigue pre- and post-session.Results: Significant improvements were found in terms of all outcome measures in the Hatha Yoga Group and the resistance exercise group. No improvements were found in the Control Group. Hatha yoga more improved the dimensions fatigue, self-esteem, and quality of life, whilst resistance exercise training more improved body image. Hatha yoga and resistance exercise decreased depression symptoms at a similar level.Conclusion: The results indicated that hatha yoga and resistance exercise had positive effects on mental health and well-being in sedentary adults. Hatha yoga and resistance exercise may affect different aspects of mental health and well-being. (C) 2014 Elsevier Ltd. All rights reserved

A comparison of the effects of hatha yoga and resistance exercise on mental health and well-being in sedentary adults: a pilot study.

OBJECTIVES: Physical activity has a positive effect on people's mental health and well-being. The aim of this study was to compare the effects of hatha yoga and resistance exercises on mental health and well-being in sedentary adults. DESIGN: Randomized controlled study. METHODS: Fifty-one participants aged mean (SD) 25.6 (5.7) years were randomly divided into three groups: Hatha Yoga Group, Resistance Exercise Group and Control Group. The Hatha Yoga Group and Resistance Exercise Group participated in sessions three days per week for 7 weeks and the Control Group did not participate in any sessions. All the subjects were evaluated through the Rosenberg Self-Esteem Scale, Beck Depression Inventory, Body Cathexis Scale, Nottingham Health Profile and Visual Analog Scale for fatigue pre-and post-session. RESULTS: Significant improvements were found in terms of all outcome measures in the Hatha Yoga Group and the resistance exercise group. No improvements were found in the Control Group. Hatha yoga more improved the dimensions fatigue, self-esteem, and quality of life, whilst resistance exercise training more improved body image. Hatha yoga and resistance exercise decreased depression symptoms at a similar level. CONCLUSION: The results indicated that hatha yoga and resistance exercise had positive effects on mental health and well-being in sedentary adults. Hatha yoga and resistance exercise may affect different aspects of mental health and well-being

Evaluating the effects of different strength training techniques on anthropometric structure and endurance of healthy quadriceps femoris muscle

This study was planned to examine the effect of superimposed, resistance exercise and electrical stimulation of the 3 different training on anthropometric characteristics and endurance of healthy quadriceps femoris muscle in untrained healthy young adults. Forty eight untrained healthy young subject aged between 21-26 (22.43±1.12) participated the study. Subjects were divided into 3 groups: Resistance Training Group (RTG) (n = 17); Electrical Stimulation Group (ESG) (n = 15) and Superimposed Training Group (STG) (n = 16). Dominant leg was determined by the selected tests and training was given three times a week for 6 weeks. Knee circumference, thigh circumference, skinfold measurements, repetition of 10-pound work, step-up, step-down an squatting on one leg test of subjects were taken pre-post training. The results indicated that electrical stimulation was not sufficient alone to strengthen the quadriceps femoris muscle. It is thought that training programs including voluntary muscle contraction must be main component of rehabilitation for muscle hypertrophy. In addition, resistance training has been effective in reducing adipose tissue. © 2012 Science Alert