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Sensitivity Measures (sensitivity + measure)

Distribution by Scientific Domains

Medical Sciences	60%

Selected Abstracts

Association of tobacco dependence and quit attempt duration with Rasch-modeled withdrawal sensitivity using retrospective measures

ADDICTION, Issue 6 2009
Harold S. Javitz
ABSTRACT Aim To examine whether Rasch modeling would yield a unidimensional withdrawal sensitivity measure correlating with factors associated with successful smoking cessation. Design The psychometric Rasch modeling approach was applied to estimate an underlying latent construct (withdrawal sensitivity) in retrospective responses from 1644 smokers who reported quitting for 3 or more months at least once. Setting Web-based, passcode-controlled self-administered computerized questionnaire. Participants Randomly selected convenience sample of 1644 adult members of an e-mail invitation-only web panel drawn from consumer databases. Measurements Lifetime Tobacco Use Questionnaire, assessing tobacco use across the life-span, including demographics and respondent ratings of the severity of withdrawal symptoms experienced in respondents' first and most recent quit attempts lasting 3 or more months. Findings Rasch-modeled withdrawal sensitivity was generally unidimensional and was associated with longer periods of smoking cessation. One latent variable accounted for 74% of the variability in symptom scores. Rasch modeling with a single latent factor fitted withdrawal symptoms well, except for increased appetite, for which the fit was marginal. Demographic variables of education, gender and ethnicity were not related to changes in sensitivity. Correlates of greater withdrawal sensitivity in cessation attempts of at least 3 months included younger age at first quit attempt and indicators of tobacco dependence. Conclusion The relationship between tobacco dependence symptoms and Rasch-model withdrawal sensitivity defines further the relationship between sensitivity and dependence. The findings demonstrate the utility of modeling to create an individual-specific sensitivity measure as a tool for exploring the relationships among sensitivity, dependence and cessation. [source]

Moment independent and variance-based sensitivity analysis with correlations: An application to the stability of a chemical reactor

INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 11 2008
E. Borgonovo
Recent works have attracted interest toward sensitivity measures that use the entire model output distribution, without dependence on any of its particular moments (e.g., variance). However, the computation of moment-independent importance measures in the presence of dependencies among model inputs has not been dealt with yet. This work has two purposes. On the one hand, to introduce moment independent techniques in the analysis of chemical reaction models. On the other hand, to allow their computation in the presence of correlations. To do so, a new approach based on Gibbs sampling is presented that allows the joint estimation of variance-based and moment independent sensitivity measures in the presence of correlations. The application to the stability of a chemical reactor is then discussed, allowing full consideration of historical data that included a correlation coefficient of 0.7 between two of the model parameters. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 687,698, 2008 [source]

The Genetics of Acute Functional Tolerance and Initial Sensitivity to Ethanol for an Ataxia Test in the LSxSS RI Strains

ALCOHOLISM, Issue 5 2000
Vaughn M. Gehle
Background: It has been proposed that development of tolerance to the behavioral effects of ethanol depends on the degree of impairment produced by the drug; that is, more sensitive individuals should develop greater tolerance. Tests of this hypothesis with respect to acute functional tolerance have produced contradictory results. We tested the hypothesis by examining the genetic relationship between initial sensitivity and acute functional tolerance in the LSXSS recombinant inbred mice. Methods: We tested mice for initial sensitivity to the ataxic effects of 1.75 g/kg of ethanol in a stationary dowel balance test by determining blood and brain ethanol concentrations at fall. Acute tolerance to the ataxic effects of ethanol was determined by measuring blood ethanol concentration (BEC) at regain of dowel balance ability after the first injection (BEC1RB) and after a second ethanol injection of 2.0 g/kg (BEC2RB). Acute tolerance was quantified by the difference in ethanol concentration at the two regains of balance (BEC2RB , BEC1RB) or by the difference between the second regain and one of the initial sensitivity measures (BEC2RB , initial sensitivity). Results: Four different measures of initial sensitivity were taken: two that used BEC values and two that used forebrain or hindbrain ethanol concentrations. We calculated acute tolerance values by using each of these initial sensitivity measures plus BEC2RB. No evidence of a genetic relationship between initial sensitivity and acute tolerance was found, which suggests that these are two independent phenomena with respect to stationary dowel balance. Conclusions: Three conclusions can be drawn from this work: (1) Orbital sinus BEC at early time points (<5 min postinjection) may or may not accurately reflect brain EC in mice, dependent on genotype; (2) there is no genetic relationship between initial sensitivity and acute tolerance to stationary dowel ataxia in the LSXSS RIs; and (3) sex-specific factors affect low-dose ethanol responses on the stationary dowel. [source]

Evaluation of Melbourne Edge Test contrast sensitivity measures in the visually impaired

OPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 4 2005
James S. Wolffsohn
Abstract Aim:, Contrast sensitivity (CS) provides important information on visual function. This study aimed to assess differences in clinical expediency of the CS increment-matched new back-lit and original paper versions of the Melbourne Edge Test (MET) to determine the CS of the visually impaired. Methods:, The back-lit and paper MET were administered to 75 visually impaired subjects (28,97 years). Two versions of the back-lit MET acetates were used to match the CS increments with the paper-based MET. Measures of CS were repeated after 30 min and again in the presence of a focal light source directed onto the MET. Visual acuity was measured with a Bailey,Lovie chart and subjects rated how much difficulty they had with face and vehicle recognition. Results:, The back-lit MET gave a significantly higher CS than the paper-based version (14.2 ± 4.1 dB vs 11.3 ± 4.3 dB, p < 0.001). A significantly higher reading resulted with repetition of the paper-based MET (by 1.0 ± 1.7 dB, p < 0.001), but this was not evident with the back-lit MET (by 0.1 ± 1.4 dB, p = 0.53). The MET readings were increased by a focal light source, in both the back-lit (by 0.3 ± 0.81, p < 0.01) and paper-based (1.2 ± 1.7, p < 0.001) versions. CS as measured by the back-lit and paper-based versions of the MET was significantly correlated to patients' perceived ability to recognise faces (r = 0.71, r = 0.85 respectively; p < 0.001) and vehicles (r = 0.67, r = 0.82 respectively; p < 0.001), and with distance visual acuity (both r = ,0.64; p < 0.001). Conclusions:, The CS increment-matched back-lit MET gives higher CS values than the old paper-based test by approximately 3 dB and is more repeatable and less affected by external light sources. Clinically, the MET score provides information on patient difficulties with visual tasks, such as recognising faces. [source]