800 research outputs found

    Rethinking clinical trials of transcranial direct current stimulation: Participant and assessor blinding is inadequate at intensities of 2mA

    Get PDF
    Copyright @ 2012 The Authors. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and 85 reproduction in any medium, provided the original author and source are credited. The article was made available through the Brunel University Open Access Publishing Fund.Background: Many double-blind clinical trials of transcranial direct current stimulation (tDCS) use stimulus intensities of 2 mA despite the fact that blinding has not been formally validated under these conditions. The aim of this study was to test the assumption that sham 2 mA tDCS achieves effective blinding. Methods: A randomised double blind crossover trial. 100 tDCS-naïve healthy volunteers were incorrectly advised that they there were taking part in a trial of tDCS on word memory. Participants attended for two separate sessions. In each session, they completed a word memory task, then received active or sham tDCS (order randomised) at 2 mA stimulation intensity for 20 minutes and then repeated the word memory task. They then judged whether they believed they had received active stimulation and rated their confidence in that judgement. The blinded assessor noted when red marks were observed at the electrode sites post-stimulation. Results: tDCS at 2 mA was not effectively blinded. That is, participants correctly judged the stimulation condition greater than would be expected to by chance at both the first session (kappa level of agreement (κ) 0.28, 95% confidence interval (CI) 0.09 to 0.47 p = 0.005) and the second session (κ = 0.77, 95%CI 0.64 to 0.90), p = <0.001) indicating inadequate participant blinding. Redness at the reference electrode site was noticeable following active stimulation more than sham stimulation (session one, κ = 0.512, 95%CI 0.363 to 0.66, p<0.001; session two, κ = 0.677, 95%CI 0.534 to 0.82) indicating inadequate assessor blinding. Conclusions: Our results suggest that blinding in studies using tDCS at intensities of 2 mA is inadequate. Positive results from such studies should be interpreted with caution.GLM is supported by the National Health & Medical Research Council of Australia ID 571090

    Movement restriction does not modulate sensory and perceptual effects of exercise-induced arm pain

    Get PDF
    BACKGROUND: Movement restriction has been proposed as an important modulator of changes in sensory and perceptual function and motor imagery performance that are observed in musculoskeletal pain syndromes. There are no empirical data to support this view. PURPOSE: The primary objective of this experiment was to determine the effects of movement restriction on local and widespread sensory, perceptual and motor imagery changes after exercise-induced muscular pain. Further objectives were to investigate whether changes in sensory perception are correlated with pain intensity and tactile acuity or motor imagery performance. METHODS: In forty healthy volunteers, delayed onset muscle soreness (DOMS) of the non-dominant elbow flexors was induced using eccentric contractions until exhaustion. Participants were then randomised into two groups: a movement restriction group (wearing a sling) or a control group (not wearing a sling). Sensory and perceptual functions were measured using a range of sensory tests and a motor imagery performance task (left/right limb judgements). RESULTS: Movement restriction did not modulate any of the measures. We found concurrent mechanical hypoesthesia (p \u3c 0.01), reduced tactile acuity (p = 0.02) and pressure hyperalgesia (p \u3c 0.01) at the painful side. We found evidence of widespread pressure hyperalgesia. Impaired tactile acuity was associated with a decrease in pain threshold to pressure (r = -0.34, p = 0.03). Motor imagery performance was unchanged (p \u3e 0.35) by pain or movement restriction. CONCLUSION: Short-term movement restriction did not influence local and widespread sensory changes induced by experimentally induced muscular pain

    Indirect learning: how emerging-market firms grow in developed markets

    Get PDF
    Some emerging-market firms have recently achieved substantial growth in developed markets despite having had little prior experience in these markets. What explains the performance of these firms? Building on the organizational learning literature, the authors argue that indirect learning (i.e., learning from the experience of others) plays a crucial role in explaining this phenomenon. Specifically, they propose that emerging-market firms that grow in developed markets overcome their lack of direct experience in such markets by learning indirectly through their leaders, competitors, and interfirm networks. The authors test their thesis by comparing the international growth in developed markets of a sample of emerging-market firms (116 Indian firms) with a sample of developed-market firms (160 U.K. firms). The results support the authors' thesis about the importance of indirect learning in explaining the international growth of emerging-market (relative to developed-market) firms in developed markets. The authors discuss the implications of these findings for policy makers in the areas of higher education, competition policy, and international trade as well as for managers in the areas of middle-management recruitment, competitor analysis and tracking, and managing interfirm networks

    Social Media Use: Attitudes, "Detox," and Craving in Typical and Frequent Users

    Get PDF
    Social media has become a core feature of daily life, with 4.8 billion users worldwide. Research on individual differences in social media use has tended to focus on the effect of differing levels of engagement on specific mental health outcomes. In contrast, few studies have directly investigated users’ own perceptions of the impact of their social media use, attempts to regulate their behavior through periods of “detox,” and the drivers that compel them to return to these platforms. Therefore, in this study, we examined users’ current attitudes toward their social media use, their awareness of the impact it had on other aspects of their lives, their experiences of self-initiated periods of “detox,” and their reasons for reengagement. A sample of 208 U.K. social media users (aged 18–28), partitioned into typical and frequent user groups using the Social Media Addiction Questionnaire and the Social Media Engagement Questionnaire, were tested on all measures. The findings, derived from both quantitative and qualitative data, showed that users across both groups were aware of the impact of overuse, and they were able to successfully engage in sustained periods of social media detox, from which they derived positive effects (e.g., on sleep, mood, productivity), and the primary driver for continued use was a desire for social connectedness and information rather than a “craving” for social media per se. Taken together, these findings provide novel data on users’ perceptions of their social media use and, in particular, evidence in support of the positive benefits of periods of social media “detox.

    Is there a Difference in Outcomes between Patients who Received a Double or Triple Arthrodesis for Hindfoot Arthritis?

    Full text link
    Introduction/Purpose: Triple arthrodesis has historically been considered the standard of treatment for arthritis of the hindfoot with or without deformity. The complications of this surgery including non-union, malunion, nerve injury, infection and wound healing problems can occur at any of the three joints. Double arthrodesis is capable of producing a similar reduction in degrees of motion and correction of foot deformity but may also cause less patient morbidity in regard to these complications due to one less joint being incorporated into the fusion procedure. What is unknown is the patient reported outcomes, specifically physical function (PF) and pain interference (PI) between these two procedures. The purpose of this study is to evaluate the clinical outcomes for hindfoot deformity using a triple compared to a double arthrodesis

    Transcranial direct current stimulation of the motor cortex in the treatment of chronic non-specific low back pain. A randomised, double-blind exploratory study

    Get PDF
    This exploratory study aimed to test the proof of principle that active anodal transcranial direct current stimulation (tDCS) applied to the motor cortex reduces pain significantly more than sham stimulation in a group of participants with chronic non-specific low back pain

    Comparative neurohormonal responses in patients with preserved and impaired left ventricular ejection fraction: Results of the studies of left ventricular dysfunctions (SOLVD) registry

    Get PDF
    AbstractObjectives. The aim of this study was to determine the differences in neurohumoral responses between patients with pulmonary congestion with and without impaired left ventricular ejection fraction.Background. Previous studies have established the presence of neurohumoral activation in patients with congestive heart failure. It is not known whether the activation of these neurohumoral mechanisms is related to the impairment in systolic contractility.Methods. The 898 patients recruited into the Studies of Left Ventricular Dysfunction (SOLVD) Registry substudy were examined to identify those patients with pulmonary congestion on chest X-ray film who had either unpaired (<- 45%, group I) or preserved (> 45%, group II) left ventricular ejection fraction. Plasma norepinephrine, plasma renin activity, arginine vasopressin and atrial natriuretic peptide levels were measured in these two groups of patients and compared with values in matched control subjects,Results. Distribution of the New York Heart Association symptom classification was the same in the two groups of patients. Compared with control subjects, patients in group II with pulmonary congestion and preserved ejection fraction had no activation of the neurohumoral mechanisms, except for a small but statistically significant increase in arginine vasopressin and plasma renin activity. Compared with patients in group II, those in group I with pulmonary congestion and unpaired ejection fraction had significant increases in plasma norepinephrine (p < 0.002), plasma renin activity (p < 0.02) and atrial natriuretic peptide levels (p < 0.0007). When we controlled for baseline differences between groups I and II, the between-group differences in plasma norepinephrine (p < 0.02) and atrial natriuretic peptide (p < 0.002) remained significant. However, plasma renin activity was not significantly different between groups I and II. When the effects of diuretic agents and angiotensinconverting enzyme inhibitors were adjusted, patients with lower ejection fraction were found to have significantly higher plasma norepinephrine and atrial natriuretic peptide levels.Conclusions. The results point to the importance of the decrease in left ventricular ejection fraction as one of the mechanisms for activation of neurohormones in patients with heart failure
    corecore