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Testing Methodology (testing + methodology)

Distribution by Scientific Domains

Medical Sciences	60%

Selected Abstracts

Sensitive skin: mechanisms and diagnosis

INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 1 2005
G. Primavera
Synopsis Sensitive skin is a condition of subjective cutaneous hyperreactivity to environmental factors. Subjects experiencing this condition report exaggerated reactions when their skin is in contact with cosmetics, soaps and sunscreens, and they often report worsening after exposure to dry and cold climate. Although no sign of irritation is commonly detected, itching, burning, stinging and a tight sensation are constantly present. Generally substances that are not commonly considered irritants are involved in this abnormal response. They include many ingredients of cosmetics such as: dimethyl sulfoxide, benzoyl peroxide preparations, salicylic acid, propylene glycol, amyldimethylaminobenzoic acid and 2-ethoxyethyl methoxycinnamate. Sensitive skin and subjective irritation are widespread but still far from being completely defined and understood. The aim of this paper is to summarize the relevant literature in order to elucidate the underlying mechanisms of sensitive skin and the best testing methodologies for investigation of sensitive skin. Résumé La peau sensible est la traduction d'une hyperréactivité cutanée subjective provoquée par les facteurs environnementaux. Les sujets qui en souffrent rapportent des réactions exagérées quand leur peau est au contact de cosmétiques, de savons, de produits solaires, phénomènes souvent aggravés après exposition à un climat froid et sec. Bien qu'aucun signe d'irritation ne soit généralement perçu, démangeaisons, brûlurepicotement et sensation de tiraillement sont constamment présents. En général des substances qui ne sont pas considérées comme des agents irritants sont impliquées dans ces réactions anormales. Elles incluent de nombreux ingrédients présents dans les produits cosmétiques comme le diméthyl sulfoxyde, les préparations aux peroxyde de benzoïle, l'acide salicylique, le propylène glycol, l'acide amyldiméthylaminobenzoïque et le 2-éthoxyéthylméthoxycinnamate. La peau sensible et l'irritation subjective sont des troubles répandus mais très loin d'être correctement définis et compris. L'objet de cet article est de résumer la littérature pertinente dans ces domaines afin d'élucider les mècanismes sous jacents à la peau sensible et d'appréhender les meilleures méthodologies de tests pour l'étudier. [source]

Comparison of the prevalence of fructose and lactose malabsorption across chronic intestinal disorders

ALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 2 2009
J. S. BARRETT
Summary Background, Fructose malabsorption, lactose malabsorption and an early rise in breath hydrogen after lactulose (ERBHAL) may play roles in induction of symptoms in gastrointestinal conditions. Aim, To compare prevalence and interactions of fructose malabsorption, lactose malabsorption and ERBHAL among healthy subjects and those with chronic intestinal disorders using consistent breath hydrogen testing methodologies. Methods, Consecutive series of Caucasian patients with Crohn's disease (n = 91), ulcerative colitis (56), functional gastrointestinal disorders (FGID) (201), coeliac disease (136) and 71 healthy volunteers underwent breath hydrogen testing using lactulose, fructose and lactose. Results, Early rise in breath hydrogen after lactulose occurred more commonly in healthy controls (39%) than in Crohn's disease (20%) and untreated coeliac disease (14%; P < 0.008), but not FGID (27%), ulcerative colitis (26%) or treated coeliac disease (29%). Fructose malabsorption was more frequent in Crohn's disease (61%) than other groups (33,44%, P < 0.05). Lactose malabsorption was most common in Crohn's disease (42%) and ulcerative colitis (40%) and uncommon (10%) in 79 patients with newly diagnosed coeliac disease. In Crohn's disease, concurrent Fructose malabsorption and lactose malabsorption was most common (29%), and the association of fructose malabsorption with ERBHAL seen overall (62%) was not observed (36%, P < 0.0001). Conclusions, Carbohydrate malabsorption and ERBHAL are normal physiological phenomena. The abnormal patterns observed in Crohn's disease may have pathogenic importance. [source]

Measurement of Viscosity of Densifying Glass-Based Systems by Isothermal Cyclic Loading Dilatometry

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2004
Aravind Mohanram
This study describes the isothermal cyclic loading dilatometry (ICLD) technique to measure the viscosity of glass-based materials. We demonstrate its merit relative to constant-load techniques in minimizing the stress history effects (changes in shrinkage anisotropy and sample microstructure) that arise due to the application of an external load. A constant-load test overestimates the viscosity by an order of magnitude compared with a cyclic load test. To obtain accurate viscosity data, maximum loading rates and longer unloading periods are desirable as they reduce effects of shrinkage anisotropy on viscosity values. Representative data for a low-temperature cofired ceramic (LTCC) material are reported. Nonparametric statistical tests revealed insignificant differences between the viscosity data sets at 5% significance level and thus indicate good reproducibility of the testing methodology. [source]

On the use of non-local prior densities in Bayesian hypothesis tests

JOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES B (STATISTICAL METHODOLOGY), Issue 2 2010
Valen E. Johnson
Summary., We examine philosophical problems and sampling deficiencies that are associated with current Bayesian hypothesis testing methodology, paying particular attention to objective Bayes methodology. Because the prior densities that are used to define alternative hypotheses in many Bayesian tests assign non-negligible probability to regions of the parameter space that are consistent with null hypotheses, resulting tests provide exponential accumulation of evidence in favour of true alternative hypotheses, but only sublinear accumulation of evidence in favour of true null hypotheses. Thus, it is often impossible for such tests to provide strong evidence in favour of a true null hypothesis, even when moderately large sample sizes have been obtained. We review asymptotic convergence rates of Bayes factors in testing precise null hypotheses and propose two new classes of prior densities that ameliorate the imbalance in convergence rates that is inherited by most Bayesian tests. Using members of these classes, we obtain analytic expressions for Bayes factors in linear models and derive approximations to Bayes factors in large sample settings. [source]

Morphometric characterization of murine articular cartilage,Novel application of confocal laser scanning microscopy

MICROSCOPY RESEARCH AND TECHNIQUE, Issue 9 2009
Kathryn S. Stok
Abstract A new technique for characterization of the three-dimensional morphology of murine articular cartilage is proposed. The technique consists of a novel application of confocal laser scanning microscopy (CLSM), where the objective was to develop and validate it for cartilage measurements in murine joints. Murine models are used in arthritis research, because they are well-described for manipulating the disease pathophysiology, facilitating our understanding of the disease, and identifying new targets for therapy. A calibration and reproducibility study was carried out to provide a consistent testing methodology for quantification of murine joints. The proximal tibial condyles from male C57BL/6 mice were scanned using a CLS microscope with an isotropic voxel size of 5.8 ,m. Measurements and analyses were repeated three times on different days, and in a second step the analysis was repeated three times for a single measurement. Calculation of precision errors (coefficient of variation) for cartilage thickness and volume was made. The bias of the system was estimated through comparison with histology. This technique showed good precision, with errors in the repeated analysis ranging from 0.63% (lateral thickness) to 3.48% (medial volume). The repeated analysis alone was robust, with intraclass correlations for the different compartments between 0.918 and 0.991. Measurement bias was corrected by scaling the confocal images to 32% of their width to match histology. CLSM provided a fast and reproducible technique for gathering 3D image data of murine cartilage and will be a valuable tool in understanding the efficacy of arthritis treatments in murine models. Microsc. Res. Tech. 2009. © 2009 Wiley-Liss, Inc. [source]