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Linear Multiple Regression Analysis (linear + multiple_regression_analysis)
Selected AbstractsSolvent and structural effects on the oxidation of 2,6-diphenyl-piperidin-4-ones by quinolinium chlorochromateINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 10 2002S. Saravana Kanna The kinetics of oxidation of 3-R-2,6-diphenyl-piperidin-4-ones (where R = H, Me, Et, and i -Pr) by quinolinium chlorochromate has been studied under pseudo-first-order conditions in different pure (protic and aprotic) solvents. The rate data is correlated with different solvent parameters using linear multiple regression analysis. From the regression coefficients, information on the solvent,reactant and the solvent,transition state interactions is obtained and the solvation models are proposed. Reasons for the difference in reactivity with structure are also discussed. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 585,588, 2002 [source] Thermodynamic analysis of subcooling and superheating effects of alternative refrigerants for vapour compression refrigeration cyclesINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 5 2006encan Abstract This paper presents a computer-based first law and exergy analysis applied to vapour compression refrigeration systems for determining subcooling and superheating effects of environmentally safe new refrigerants. Three refrigerants are considered: R134a, R407c and R410a. It is found that subcooling and superheating temperatures directly influence the system performance as both condenser and evaporator temperatures are affected. The thermodynamic properties of the refrigerants are formulated using artificial neural network (ANN) methodology. Six ANNs were trained to predict various properties of the three refrigerants. The training and validation of the ANNs were performed with good accuracy. The correlation coefficient obtained when unknown data were used to the networks were found to be equal or very near to 1 which is very satisfactory. Additionally, the present methodology proved to be much better than the linear multiple regression analysis. From the analysis of the results it is found that condenser and evaporator temperatures have strong effects on coefficient of performance (COP) and system irreversibility. Also both subcooling and superheating affect the system performance. This effect is similar for R134a and R407c, and different for R410a. Copyright © 2005 John Wiley & Sons, Ltd. [source] Individual difference in the number of chewing strokes and its determinant factorsJOURNAL OF ORAL REHABILITATION, Issue 2 2006T. UEDA summary, This study was carried out to clarify the distribution and individual variation of the number of chewing strokes before last swallowing (NCS), as well as to assess the factors that affect NCS, when dentulous adults masticate the same type of food. NCS was measured in 75 dentulous adults using gummy candies. Measurements were repeated five times to obtain the average and variation. Moreover, the correlation of NCS with various physiological factors (lateral width and vertical distance of chewing loop, angle of opening and closing path, opening and closing time, occlusal time, masticatory performance, number of occlusal contact points, occlusal contact area, occlusal force, flow rate of whole saliva and viscosity of whole saliva) and 28 personality factors were analysed by both of the single variate analysis and the multivariate analysis. The results showed that the average NCS was 41·0 ± 16·0, and the coefficient of variation was 0·090 ± 0·040. Additionally, the correlation between NCS and each factor was investigated, and found that any of these factors did not function as a single determinant for NCS. Following, determinant factors were further examined by the stepwise method of linear multiple regression analysis. From these analysis we found that when opening and closing time and four personality factors were combined, they were significantly involved in determining NCS (P < 0·01). Therefore, we conclude that individual NCS until last swallowing is not determined by a sole, specific physiological factor but is affected by multiple factors including personality. [source] Job characteristics and the subjective oral health of Australian workersAUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH, Issue 3 2004Anne E. Sanders Objectives: To examine the associations between hours worked, job security, skill maintenance and work and home interference and subjective oral health; and to compare findings for different occupational groups. Methods: Data were collected in 1999 from a random stratified sample of households in all Australian States and Territories using a telephone interview and a questionnaire survey. Subjective oral health was evaluated with the short form Oral Health Impact Profile (OHIP-14), which assesses the adverse impact of oral conditions on quality of life. Results: Data were obtained for 2,347 dentate adults in the workforce. In the 12 months preceding the survey, 51.9% had experienced oral pain and 31.0% reported psychological discomfort from dental problems. Males, young adults, Australian-born workers, and those in upper-white collar occupations reported lower mean OHIP-14 scores (ANOVA p<0.001). Having controlled for the effects sex, age, country of birth and socio-economic factors in a linear multiple regression analysis, hours worked, skill maintenance and work and home interference were significantly associated with OHIP-14 scores for all workers. While part-time work was associated with higher OHIP-14 among upper white-collar workers, working >40 hours a week was associated with higher OHIP-14 scores for other workers. Conclusions: Aspects of the work environment are associated with the subjective oral health of workers. Because these contexts are subject to only limited control by individual workers, their influence is a public health issue. [source] Vitamin D status in female patients with primary hyperparathyroidism: does it play a role in skeletal damage?CLINICAL ENDOCRINOLOGY, Issue 1 2004Vincenzo Carnevale Summary objective, Vitamin D deficiency, even subclinical, has been considered to worsen the skeletal damage in primary hyperparathyroidism (PHPT). Our study aimed to investigate the impact of vitamin D status on skeletal involvement in PHPT. design and measurements, A cross-sectional study was designed involving 62 female patients with PHPT. Serum total calcium (tCa), phosphate (P), creatinine (Cr) and total alkaline phosphatase activity (AP), together with 24-h (uCa 24 h) and spot fasting (uCa/Cr) urinary calcium, were measured by autoanalyser; ionized calcium (iCa) was assessed by an ion-specific electrode; intact parathyroid hormone (PTH) was measured by immunoradiometric assay (IRMA) and 25-hydroxyvitamin D (25-OHD) by radioimmunoassay (RIA). Bone mineral density (BMD) was measured by dual energy X-ray absorptiometry (DXA) at lumbar spine in 58 patients, and at femoral neck, Ward's triangle, greater trochanter, intertrochanteric line and total hip in 56 patients. The associations of all variables with age, 25-OHD, body mass index (BMI) and PTH were studied by linear multiple regression analysis, using progressively restricted models. results, The model including age, 25-OHD, PTH and BMI showed significant regression with BMD values. PTH, age and BMI exerted a leading role in determining such a significance, while no significant regression was found between the parameters studied and 25-OHD; this was confirmed by Pearson's linear correlation analysis. The progressively restricted models showed significant regression of BMD at femoral neck, femoral intertrochanteric line and total hip with age, BMI and PTH. BMD measured at the Ward's triangle and greater trochanter showed significant regression with age and BMI, and that measured at lumbar spine with age. conclusions, Our data indicate that in primary hyperparathyroidism patients the influence of 25-hydroxyvitamin D levels on bone mineral density, if any, was overwhelmed by the effects of parathyroid hormone excess, age and body mass index. The latter unequally affected bone mineral density of various measured sites with different composition. [source] | ||||||||||