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Various Methods Used (various + methods_used)

Distribution by Scientific Domains

Medical Sciences	50%

Selected Abstracts

Defining hormone replacement therapy in longitudinal studies: impact on measures of effect

PHARMACOEPIDEMIOLOGY AND DRUG SAFETY, Issue 4 2004
Ilona Csizmadi PhD
Abstract Data from a nested case-control study, designed to examine the effect of hormone replacement therapy (HRT) on colorectal cancer risk, were analyzed to determine the effect of exposure definition on the estimation of risk ratios (RR). A prescription drug plan database was used to ascertain HRT prescriptions dispensed prior to index dates to cases (n,=,3059) and age-matched controls (n,=,12,116). HRT exposure was defined as ,prescription' and ,tablet' counts, ,conjugated estrogen only' and a method based on proportions of minimum exposure to a number of estrogens (SUM-P3 and SUM-P12). The effect of HRT was described with reference to ,ever', <,5 and ,,5 years of HRT use. Conditional logistic regression was used to estimate ORs and 95% confidence intervals (CI). Adjusted ORs for ,ever use' of HRT ranged from 0.72 (95%CI: 0.60,0.88) to 0.86 (95%CI: 0.76,0.99); for <5 years use, from 0.70 (95%CI: 0.56,0.88) to 0.89 (95%CI: 0.78,1.01) and for ,5 year of HRT use, from 0.74 (95%CI: 0.59,0.92) to 0.98 (95%CI: 0.42,2.26). Various methods used to define HRT exposure produce a range of estimated ORs that vary in magnitude similar to results reported in the literature from observational studies investigating the association between HRT and colorectal cancer. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Analysis of the current methods used to size a wind/hydrogen/fuel cell-integrated system: A new perspective

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 12 2010
H. G. Geovanni
Abstract As an alternative to the production and storage of intermittent renewable energy sources, it has been suggested that one can combine several renewable energy technologies in one system, known as integrated or hybrid system, that integrate wind technology with hydrogen production unit and fuel cells. This work assesses the various methods used in sizing such systems. Most of the published papers relate the use of simulation tools such as HOMER, HYBRID2 and TRNSYS, to simulate the operation of different configurations for a given application in order to select the best economic option. But, with these methods one may not accurately determine certain characteristics of the energy resources available on a particular site, the profiles of estimated consumption and the demand for hydrogen, among other factors, which will be the optimal parameters of each subsystem. For example, velocity design, power required for the wind turbine, power required for the fuel cell and electrolyzer and the storage capacity needed for the system. Moreover, usually one makes excessive use of bi-parametric Weibull distribution function to approximate the histogram of the observed wind to the theoretical, which is not appropriate when there are bimodal frequency distributions of wind, as is the case in several places in the world. A new perspective is addressed in this paper, based on general system theory, modeling and simulation with a systematic approach and the use of exergoeconomic analysis. There are some general ideas on the advantages offered in this method, which is meant for the implementation of wind/hydrogen/fuel cell-integrated systems and in-situ clean hydrogen production. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Onion Cells After High Pressure and Thermal Processing: Comparison of Membrane Integrity Changes Using Different Analytical Methods and Impact on Tissue Texture

JOURNAL OF FOOD SCIENCE, Issue 7 2010
Maria E. Gonzalez
Abstract:, Two different analytical methods were evaluated for their capacity to provide quantitative information on onion cell membrane permeability and integrity after high pressure and thermal processing and to study the impact of these processing treatments on cell compartmentalization and texture quality. To determine changes in cell membrane permeability and/or integrity the methodologies utilized were: (1) measurement of a biochemical product, pyruvate, formed as a result of membrane permeabilization followed by enzymatic activity and (2) leakage of electrolytes into solution. These results were compared to previously determined methods that quantified cell viability and 1H-NMR T2 of onions. These methods allowed for the monitoring of changes in the plasma and tonoplast membranes after high pressure or thermal processing. High pressure treatments consisted of 5 min holding times at 50, 100, 200, 300, or 600 MPa. Thermal treatments consisted of 30 min water bath exposure to 40, 50, 60, 70, or 90 °C. There was strong agreement between the methods in the determination of the ranges of high pressure and temperature that induce changes in the integrity of the plasma and tonoplast membranes. Membrane rupture could clearly be identified at 300 MPa and above in high pressure treatments and at 60 °C and above in the thermal treatments. Membrane destabilization effects could already be visualized following the 200 MPa and 50 °C treatments. The texture of onions was influenced by the state of the membranes and was abruptly modified once membrane integrity was lost. Practical Application:, In this study, we used chemical, biochemical, and histological techniques to obtain information on cell membrane permeability and onion tissue integrity after high pressure and thermal processing. Because there was strong agreement between the various methods used, it is possible to implement something relatively simple, such as ion leakage, into routine quality assurance measurements to determine the severity of preservation methods and the shelf life of processed vegetables. [source]

Continent catheterizable conduits: which stoma, which conduit and which reservoir?

BJU INTERNATIONAL, Issue 1 2002
H.F. McAndrew
Objective To assess the outcome of the various methods used in creating continent catheterizable conduits. Patients and methods The case notes were reviewed from 89 patients who underwent the formation of 112 continent catheterizable conduits. Results Sixty-five conduits were Mitrofanoff and 47 were antegrade colonic enema (ACE); 21 patients had both. At a mean follow-up of 34 months, 95 (85%) conduits were still in use. There was no difference in complications between the Mitrofanoff and ACE conduits; 109 (97%) conduits were continent and stomal stenosis occurred 35 (31%). There was no significant difference relating to the conduit used, the reservoir, the stoma type or the stoma site. Only 39% of patients required no revisional surgery. Conclusion Although urinary and fecal continence can be achieved in most patients there is a high burden of complications and revisional surgery. All patients should be counselled accordingly. [source]