Numerical Optimization of the Thermal Field in Bridgman Detached Growth

The global modeling of the thermal field in two vertical Bridgman-like crystal growth configurations, has been performed to get optimal thermal conditions for a successful detached growth of Ge and CdTe crystals. These computations are performed using the CrysMAS code and expand upon our previous analysis [1] that propose a new mechanism involving the thermal field and meniscus position to explain stable conditions for dewetted Bridgman growth. The analysis of the vertical Bridgman configuration with two heaters, used by Palosz et al. for the detached growth of Ge, shows, consistent with their results, that the large wetting angle of germanium on boron nitride surfaces was an important factor to promote a successful detached growth. Our computations predict that by initiating growth much higher into the hot zone of the furnace, the thermal conditions will be favorable for continued detachment even for systems that did not exhibit high contact angles. The computations performed for a vertical gradient freeze configuration with three heaters representative of that used for the detached growth of CdTe, show favorable thermal conditions for dewetting during the entirely growth run described. Improved thermal conditions are also predicted for coated silica crucibles when the solid-liquid interface advances higher into the hot zone during the solidification process. The second set of experiments on CdTe growth described elsewhere has shown the reattachment of the crystal to the crucible after few centimeters of dewetted growth. The thermal modeling of this configuration shows a second solidification front appearing at the top of the sample and approaching the middle line across the third heater. In these conditions, the crystal grows detached from the bottom, but will be attached to the crucible in the upper part because of the solidification without gap in this region. The solidification with two interfaces can be avoided when the top of the sample is positioned below the middle position of the third furnace

Short-term efficacy of physical interventions in osteoarthritic knee pain. A systematic review and meta-analysis of randomised placebo-controlled trials.

BACKGROUND: Treatment efficacy of physical agents in osteoarthritis of the knee (OAK) pain has been largely unknown, and this systematic review was aimed at assessing their short-term efficacies for pain relief. METHODS: Systematic review with meta-analysis of efficacy within 1-4 weeks and at follow up at 1-12 weeks after the end of treatment. RESULTS: 36 randomised placebo-controlled trials (RCTs) were identified with 2434 patients where 1391 patients received active treatment. 33 trials satisfied three or more out of five methodological criteria (Jadad scale). The patient sample had a mean age of 65.1 years and mean baseline pain of 62.9 mm on a 100 mm visual analogue scale (VAS). Within 4 weeks of the commencement of treatment manual acupuncture, static magnets and ultrasound therapies did not offer statistically significant short-term pain relief over placebo. Pulsed electromagnetic fields offered a small reduction in pain of 6.9 mm [95% CI: 2.2 to 11.6] (n = 487). Transcutaneous electrical nerve stimulation (TENS, including interferential currents), electro-acupuncture (EA) and low level laser therapy (LLLT) offered clinically relevant pain relieving effects of 18.8 mm [95% CI: 9.6 to 28.1] (n = 414), 21.9 mm [95% CI: 17.3 to 26.5] (n = 73) and 17.7 mm [95% CI: 8.1 to 27.3] (n = 343) on VAS respectively versus placebo control. In a subgroup analysis of trials with assumed optimal doses, short-term efficacy increased to 22.2 mm [95% CI: 18.1 to 26.3] for TENS, and 24.2 mm [95% CI: 17.3 to 31.3] for LLLT on VAS. Follow-up data up to 12 weeks were sparse, but positive effects seemed to persist for at least 4 weeks after the course of LLLT, EA and TENS treatment was stopped. CONCLUSION: TENS, EA and LLLT administered with optimal doses in an intensive 2-4 week treatment regimen, seem to offer clinically relevant short-term pain relief for OAK

Test-retest reliability of the Short-Form McGill Pain Questionnaire

Objectives: No previous study has adequately demonstrated the test-retest reliability of the Short-Form McGill Pain Questionnaire, yet it is increasingly being used as a measure of pain. This study evaluates the test-retest reliability in patients with osteoarthritis. Methods: A prospective, observational cohort study was undertaken using serial evaluation of 57 patients at 2 time points. A sample of patients awaiting primary hip or knee joint replacement surgery were recruited in clinic or via mail (mean age 64.8 years). Short-Form McGill Pain Questionnaires were delivered by mail 5 days apart, and a supplementary questionnaire was completed on the second occasion to explore if the patients’ pain report had remained stable. Results: The intraclass correlation coefficient was used as an estimate of reliability. For the total, sensory, affective, and average pain scores, high intra-class correlations were demonstrated (0.96, 0.95, 0.88, and 0.89, respectively). The current pain component demonstrated a lower intraclass correlation of 0.75. The coefficient of repeatability was calculated as an estimation of the minimum metrically detectable change. The coefficients of repeatability for the total, sensory, affective, average, and current pain components were 5.2, 4.5, 2.8, 1.4 cm, and 1.4, respectively. Discussion: Problems of adequate completion of the Short-Form McGill Pain Questionnaire were highlighted in this sample, and supervision via telephone contact was required. Patients recruited in clinic who had practiced completing the Short-Form McGill Pain Questionnaire demonstrated fewer errors than those recruited by mail. The Short-Form McGill Pain Questionnaire was demonstrated to be a highly reliable measure of pain. These results should not be generalized to a more elderly population, as increasing age was correlated with greater variability of the sensory component scores.</p

Deqi sensations without cutaneous sensory input: results of an RCT

<p>Abstract</p> <p>Background</p> <p>Deqi is defined in relation to acupuncture needling as a sensory perception of varying character. In a recently published sham laser validation study, we found that subjects in the verum and the sham laser group experienced deqi sensations. Therefore, we aim to further analyze whether the perceptions reported in the two study arms were distinguishable and whether expectancy effects exhibited considerable impact on our results.</p> <p>Methods</p> <p>A detailed re-analysis focusing on deqi sensations was performed from data collected in a previously published placebo-controlled, double-blind, clinical cross-over trial for a sham laser evaluation. Thirty-four healthy volunteers (28 ± 10.7 years; 16 women, 18 men) received two laser acupuncture treatments at three acupuncture points LI4 (hégu), LU7 (liéque), and LR3 (táichong); once by verum laser and once using a sham device containing an inactive laser in randomized order. Outcome measures were frequency, intensity (evaluated by visual analogue scale; VAS), and quality of the subjects' sensations perceived during treatments (assessed with the "acupuncture sensation scale").</p> <p>Results</p> <p>Both, verum and the sham laser acupuncture result in similar deqi sensations with regard to frequency (p-value = 0.67), intensity (p-value = 0.71) and quality (p-values between 0.15 - 0.98). In both groups the most frequently used adjectives to describe these perceptions were "spreading", "radiating", "tingling", "tugging", "pulsing", "warm", "dull", and "electric". Sensations reported were consistent with the perception of deqi as previously defined in literature. Subjects' conviction regarding the effectiveness of laser acupuncture or the history of having received acupuncture treatments before did not correlate with the frequency or intensity of sensations reported.</p> <p>Conclusions</p> <p>Since deqi sensations, described as sensory perceptions, were elicited without any cutaneous sensory input, we assume that they are a product of non-specific effects from the overall treatment procedure. Expectancy-effects due to previous acupuncture experience and belief in laser acupuncture do not seem to play a major role in elicitation of deqi sensations. Our results give hints that deqi might be a central phenomenon of awareness and consciousness, and that its relevance should be taken into account, even in clinical trials. However, further research is required to understand mechanisms underlying deqi.</p

Numerical analysis of MHD effects resulting from spatial variations of high magnetic fields applied to a rectangular duct flow

International audienceA fully three dimensional numerical analysis is performed in order to study turbulent flow of liquid metals in rectangular ducts under the influence of high magnetic fields. The goal of this analysis is to improve the level of understanding MHD effects in liquid metal cooled fusion reactor. The turbulent flow is computed in the case of uniform and non-uniform high magnetic fields. The flow computations for a duct in a non-uniform magnetic field, show M-shaped velocity profiles in the upstream region of the longitudinal plane of the flow, and respectively low intensity wall jets in the downstream region. This flow pattern is explained by the induced electrical currents which are closed in both the longitudinal and transversal planes, generating Lorentz forces acting parallel and, respectively, perpendicular to the flow. When the applied magnetic field is uniform, the velocity distribution is slightly affected by the Lorentz forces. The results show flattened velocity profiles in the core region, and no jet flow emerging near the walls. This result is explained by the closure path of eddy currents only in the transversal plane of the flow. By introducing some variation of the axial magnetic field in the computation, no significant changes are observed in the velocity profiles. The velocity profiles are significantly affected by the axial gradient of the magnetic field, only at the entrance and, respectively, at the exit of the rectangular duct from a uniform magnetic field. The flow damping in the core region is much stronger at the entry and, respectively, at the exit side from an extended zone with uniform magnetic field, as compared to the case of a liquid metal flowing through a narrow magnetic system