1,716 research outputs found
Botanical extracts as anti-ageing preparations for the skin: a systematic review
No full textAlthough topical creams and other anti-aging products purport to reduce the appearance of aging and skin wrinkling, there has been no critical analysis in the scientific literature of their effectiveness. This systematic review critically evaluates the evidence for the effectiveness or efficacy of botanical treatments in reducing skin aging and wrinkling. MEDLINE, Embase, CINAHL®, CENTRAL and AMED databases were searched from their inception until October 2009. Reference lists of retrieved articles were hand-searched. Manufacturers and professional associations were contacted in order to identify further non-published studies. No language restrictions were applied. Only randomized clinical trials or controlled clinical trials assessing the effectiveness of botanical extracts in reducing wrinkling and aging of the skin were included. Data were extracted by two independent reviewers and methodological quality was assessed using the Jadad score and key aspects of the Cochrane risk of bias tool. Of 36 potentially relevant studies, 11 trials of botanical extracts for reducing skin wrinkling and the appearance of aging met all the inclusion criteria. No trials were identified following contact with anti-aging and cosmetic organizations, companies and professional bodies. A significant reduction in skin wrinkling was noted for date kernel extract, cork extract, soy extract, Rosaceae and peony extract. No significant reduction was noted for green tea, Vitaphenol® (a combination of green and white teas, mangosteen and pomegranate extract) or maca root. All trials were of poor methodological quality. Adverse effects were frequently not reported. In summary, there is some weak evidence to suggest that several botanical extracts may be effective in reducing the appearance of skin aging but no evidence that this effect is enduring. Independent replications with larger, more diverse samples, longer treatment durations and more rigorous study designs are required to validate these preliminary findings
Chiropractic manipulation for carpal tunnel syndrome: a systematic review
No full textBackground: Although chiropractic is most commonly used for spinal problems, many chiropractors use manipulations for the treatment of non-spinal conditions. Carpal tunnel syndrome (CTS) has been identified as one such condition. This systematic review evaluates the evidence for or against the effectiveness of chiropractic as a treatment for CTS. Methods: Eight electronic databases were searched from inception until November 2008. Reference lists of retrieved articles were hand-searched. Chiropractic associations were contacted in order to identify further non-published studies. No language restrictions were applied. Results: Of 26 potentially relevant studies, only one trial of chiropractic for CTS met all the inclusion criteria. The trial was of poor quality and reported no significant differences between the groups on any outcome measure. However, our re-analyses indicated a significant difference in favour of the control treatment (non-steroidal anti-inflammatory drugs [NSAIDs] use). Adverse effects were noted in both groups. Conclusions: There is insufficient evidence to suggest that chiropractic is effective for the treatment of CTS. Therapy should continue to focus on the use of NSAIDs, corticosteroid injection, splinting and surgical release of the median nerve. Further research into the utility of chiropractic for CTS is required. <br/
Turbulent drag reduction by hydrophobic surfaces with shear-dependent slip length
No full textThe stabilisation of a parabolic equilibrium profile in a three-dimensional (3D) turbulent channel flow for an incompressible fluid is addressed with the objective of achieving drag reduction. The formulation of this problem stems from Balogh’s work [1] where Lyapunov stability analysis was used to devise prototype feedback laws and prove global stability of the solutions. This treatment only considers the controller as a mathematical artefact, but it can actually be linked to physical control strategies modelling hydrophobic surfaces and porous media. In the former, only linear slip velocity boundary conditions (BC) were considered [8]. However, experiments [2] have suggested that the slip length may be shear-dependent. Motivated by these, the effect on drag reduction of a shear-dependent slip length surface is examined in the present study using Direct Numerical Simulations (DNS) at Re τ0 = u τ0 δ/ν ≃ 180. δ is the channel half height, u τ0 the wall-shear velocity for regular no-slip walls channel and ν the kinematic viscosity. The theoretical analysis in [5], is extended to this new model. The proposed formulation shows that the skin-friction coefficient can be reduced by tuning the parameters in the shear-dependent slip length model. The results, which verified by DNS simulations, show that by taking a slip length value based on a constant slip model [8] and combining it within a shear-dependent model, up to 50% drag reduction can be obtained. The effect of control is further assessed by formulating the Fukagata identity [4] with general boundaries; the weighted Reynolds shear-stress for each quadrant shows an enhanced reduction in the sweep/ejection events compared to the constant slip model
Complementary and alternative medicine use in England: results from a national survey
No full textObjectives:? in many countries, recent data on the use of complementary and alternative medicine (CAM) are available. However, in England, there is a paucity of such data. We sought to determine the prevalence and predictors of CAM use in England.Design:? data were obtained from the Health Survey for England 2005, a national household survey that included questions on CAM use. We used binary logistic regression modelling to explore whether demographic, health and lifestyle factors predict CAM use.Results:? data were available for 7630 respondents (household response rate 71%). Lifetime and 12-month prevalence of CAM use were 44.0% and 26.3% respectively; 12.1% had consulted a practitioner in the preceding 12 months. Massage, aromatherapy and acupuncture were the most commonly used therapies. Twenty-nine percent of respondents taking prescription drugs had used CAM in the last 12 months. Women (OR 0.491, 95% CI: 0.419, 0.577), university educated respondents (OR 1.296, 95% CI: 1.088, 1.544), those suffering from anxiety or depression (OR 1.341, 95% CI: 1.074, 1.674), people with poorer mental health (on GHQ: OR 1.062, 95% CI 1.026, 1.100) and lower levels of perceived social support (1.047, 95% CI: 1.008, 1.088), people consuming ? 5 portions of fruit and vegetables a day (OR 1.327, 95% CI: 1.124, 1.567) were significantly more likely to use CAM.Conclusion:? complementary and alternative medicine use in England remains substantial, even amongst those taking prescription drugs. These data serve as a valuable reminder to medical practitioners to ask patients about CAM use and should be routinely collected to facilitate prioritisation of the research agenda in CA
Hydrodynamical turbulence by fractal fourier decimation
No full textWe present a systematic numerical investigation of high-resolution 3D isotropic and homogeneous turbulence resolved on a decimated set of Fourier modes. Fractal decimation acts to decrease the effective dimensionality of the flow by allowing triadic interactions only in a set of Fourier modes N(k) proportional to k^DF for large k. While keeping the symmetries of the original 3D Navier-Stokes equations unchanged, a dramatic change in small-scale statistics is detected at decreasing the fractal dimension DF . Already at fractal dimension DF = 2.8, a global self-similar behaviour is observed in the inertial range of scales, the consequence of such transition are the restoration of the scaling symmetry and vorticity distribution that becomes close to Gaussian. We relate the results to the different roles of local vs non-local interactions in the energy transfer range
Least Squares Fitting of Chacón-Gielis Curves by the Particle Swarm Method of Optimization
No full textRicardo Chacón generalized Johan Gielis's superformula by introducing elliptic functions in place of trigonometric functions. In this paper an attempt has been made to fit the Chacón-Gielis curves (modified by various functions) to simulated data by the least squares principle. Estimation has been done by the Particle Swarm (PS) methods of global optimization. The Repulsive Particle Swarm optimization algorithm has been used. It has been found that although the curve-fitting exercise may be satisfactory, a lack of uniqueness of Chacón-Gielis parameters to data (from which they are estimated) poses an insurmountable difficulty to interpretation of findings.Least squares multimodal nonlinear curve-fitting; Ricardo Chacón; Jacobian Elliptic functions; Weierstrass ; Gielis super-formula; supershapes; Particle Swarm method; Repulsive Particle Swarm method of Global optimization; nonlinear programming; multiple sub-optima; global; local optima; fit; empirical; estimation; cellular automata; fractals
Introduction to mineralogy and petrology / S.K. Haldar.
No full textIncludes bibliographical references (p. 325-326) and index.xviii, 338 pages
Some Experiments on Fitting of Gielis Curves by Simulated Annealing and Particle Swarm Methods of Global Optimization
No full textIn this paper an attempt has been made to fit the Gielis curves (modified by various functions) to simulated data. The estimation has been done by two methods - the Classical Simulated Annealing (CSA) and the Particle Swarm (PS) methods - of global optimization. The Repulsive Particle Swarm (RPS) optimization algorithm has been used. It has been found that both methods are quite successful in fitting the modified Gielis curves to the data. However, the lack of uniqueness of Gielis parameters to data (from which they are estimated) is corroborated. From a technical viewpoint, this exercise may be considered as an application of CSA and RPS to extremely nonlinear least-squares curve-fitting to data that may exhibit a large number of local optima.Gielis curves; superformula; nonlinear curve-fitting; Least squares; multi-modal; local optima; global optimization; simulated annealing; particle swarm; parameters estimation
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