Modeling stage-sequential change in ordered categorical responses

Although few would dispute the usefulness of looking at behavioral change from a stage-sequential perspective, until recently the lack of appropriate modeling techniques has hampered rigorous empirical tests of stage theories. In particular, for behavioral measurements that are ordinal, there is a need for methods that represent the underlying change processes in the form of qualitative and discontinuous shifts. This article introduces a stage-sequential ordinal model by postulating that at any point in time there are a finite number of latent stages. Panel members may shift among these stages over time. The authors show that the stage-sequential model provides a general approach for both the analysis of ordinal time-dependent data and tests of various competing theories and hypotheses about psychological change processes. An analysis of a 5-year study concerning attitudes toward alcohol consumption by teenagers is presented to illustrate the modeling approach.     

Labelled Resolution for Classical and Non-classical Logics

Resolution is an effective deduction procedure for classical logic. There is no similar "resolution" system for non-classical logics (though there are various automated deduction systems). The paper presents resolution systems for intuistionistic predicate logic as well as for modal and temporal logics within the framework of labelled deductive systems. Whereas in classical predicate logic resolution is applied to literals, in our system resolution is applied to L(abelled) R(epresentation) S(tructures). Proofs are discovered by a refutation procedure defined on LRSs, that imposes a hierarchy on clause sets of such structures together with an inheritance discipline. This is a form of Theory Resolution. For intuitionistic logic these structures are called I(ntuitionistic) R(epresentation) S(tructures). Their hierarchical structure allows the restriction of unification of individual variables and/or constants without using Skolem functions. This structures must therefore be preserved when we consider other (non-modal) logics. Variations between different logics are captured by fine tuning of the inheritance properties of the hierarchy. For modal and temporal logics IRS's are extended to structures that represent worlds and/or times. This enables us to consider all kinds of combined logics.     

The epidemiology of Wilson's disease in the German Democratic Republic and current problems from the viewpoint of population genetics

Between 1949 and Nov. 30, 1977 a total of 123 cases of Wilson's disease have been registered in the GDR. Using the available statistics the incidence rate of the disease is assumed to be about 2.9/100,000, the gene frequency approx. 0.53 per cent and the heterozygote incidence 1.05 per cent, supposing that the Hardy-Weinberg law applies to a large extent. Conclusions are drawn from the available material with a view to detection of the disease infuture and to genetic family counselling.     

Separate and joint scaling of perceived odor intensity ofn-butanol and hydrogen sulfide

To determine which combination of scaling method and experimental procedure is optimal for measuring perceived odor intensity, the intensity perception of one odorous substance was scaled both separately and together with a second odorous substance in the same session. The methods used were magnitude estimation with and without a standard reference and cross-modal matching with finger span. The results show that separate and joint scalings ofn-butanol and H₂S give identical scales, regardless of scaling method. Different results are obtained in magnitude estimations with a homoquality, a heteroquality, and no standard. From these results, one would not expect to find a single true power function independent of method. Cross-modal matching with finger span may be the best choice for odor intensity scaling, since it results in the widest response range, thereby giving the best resolution.     

Risk-Taking and Smoking Tendency Among Primarily African American School Children: Moderating Influences of Peer Susceptibility

We examined the hypothesis that peer susceptibility would moderate the association between risk-taking and tendency to smoke in adolescents who were primarily African American. Participants were 88 preadolescents recruited from a 6th grade classroom in a public elementary school. We found an interaction of risk-taking and susceptibility to peer influence on smoking tendency. Specifically, a moderator effect was found for peer influence on the association between risk-taking and smoking tendency. The importance of examining peer susceptibility on health promotion and other health behaviors in children and adolescents was supported.     

A domain‐specific risk‐attitude scale: measuring risk perceptions and risk behaviors

We present a psychometric scale that assesses risk taking in five content domains: financial decisions (separately for investing versus gambling), health/safety, recreational, ethical, and social decisions. Respondents rate the likelihood that they would engage in domain‐specific risky activities (Part I). An optional Part II assesses respondents' perceptions of the magnitude of the risks and expected benefits of the activities judged in Part I. The scale's construct validity and consistency is evaluated for a sample of American undergraduate students. As expected, respondents' degree of risk taking was highly domain‐specific, i.e. not consistently risk‐averse or consistently risk‐seeking across all content domains. Women appeared to be more risk‐averse in all domains except social risk. A regression of risk taking (likelihood of engaging in the risky activity) on expected benefits and perceived risks suggests that gender and content domain differences in apparent risk taking are associated with differences in the perception of the activities' benefits and risk, rather than with differences in attitude towards perceived risk. Copyright © 2002 John Wiley & Sons, Ltd.     

RPE-based zone of normality for use in evaluating graded exercise test responses in women

The purposes of this study were to identify a zone of normality based upon ratings of perceived exertion (RPE) and compare the RPE of women with coronary artery disease to this zone. 45 healthy women (34.8 +/- 9.1 yr.) completed a Bruce treadmill test. RPE were estimated during the last minute of each workload. The zone of normality was established as the 95% confidence interval spanning the average line when RPE was regressed against MET. 51 women (66.6 +/- 9.3 yr.) with coronary artery disease completed a symptom-limited treadmill test. 31 of the women with coronary artery disease were taking beta blockers. RPE were compared to the RPE/MET relation of the zone. 57% of the women with coronary artery disease estimated RPE above the zone during the treadmill test. RPE responses above the zone of normality indicate an elevated perceptual strain for a given energy expenditure (i.e., MET). The zone of normality might be used as an aid in discriminating between normal and abnormal RPE responses during graded treadmill tests by women with coronary artery disease.     

Distinct single but not necessarily repeated tetanization is required to induce hippocampal late-LTP in the rat CA1

The protein synthesis-dependent form of hippocampal long-term potentiation (late-LTP) is thought to underlie memory. Its induction requires a distinct stimulation strength, and the common opinion is that only repeated tetani result in late-LTP whereas as single tetanus only reveals a transient early-LTP. Properties of LTP induction were compared to learning processes where repetition is often the prerequisite for a long-lasting memory. However, also single events can lead to manifested memory. If LTP subserves processes of learning, similar results should be detectable for LTP. Here we show that a single tetanus is sufficient to induce late-LTP requiring dopaminergic co-transmission during induction.