The helical twisting power determines the pitch of the helical structure produced by introducing a given concentration of chiral dopant molecules to a nematic liquid crystal phase. By using novel, twisted, periodic boundary conditions, and measuring the relative chemical potentials of right-and left-handed dopants in a twisted nematic phase, we have succeeded in measuring this property by compu...

Cognitive scientists have traditionally specified the functional components of cognitive skills on the basis of behavioural studies of normal and neurologically impaired subjects. The results of functional imaging studies are challenging these classical models because there is a high degree of overlap among the neural systems activated by tasks that share no cognitive components. This suggests ...

Many methods have been proposed to solve the age-period-cohort (APC) linear identification problem, but most are not theoretically informed and may lead to biased estimators of APC effects. One exception is the mechanism-based approach recently proposed and based on Pearl's front-door criterion; this approach ensures consistent APC effect estimators in the presence of a complete set of intermed...

Gaps between worldviews prevent students from interpreting displays literally, and thus limit the extent to which communication can be achieved by representing knowledge accurately. Hence, rather than merely representing mental models accurately, designers must focus on supporting communicative practices. I suggest four specific design principles within a mediated collaborative inquiry perspect...

Research on people's confidence in their general knowledge has to date produced two fairly stable effects, many inconsistent results, and no comprehensive theory. We propose such a comprehensive framework, the theory of probabilistic mental models (PMM theory). The theory (a) explains both the overconfidence effect (mean confidence is higher than percentage of answers correct) and the hard-easy...

Premarital cohabitation has been found to be positively correlated with the likelihood of marital dissolution in the United States. To reassess this link, I estimate proportional hazard models of marital dissolution for first marriages by using pooled data from the 1988, 1995, and 2002 surveys of the National Survey of Family Growth (NSFG). These results suggest that the positive relationship b...

This review considers experimental research that has used probability theory and statistics as a framework within which to study human statistical inference. The experiments have investigated estimates of proportions, means, variances, and correlations, both of samples and of populations. In some experiments, parameters of populations were stationary; in others, the parameters changed over time...

Objectives Drawing on new (2011-12) and previous (1993-5, 2000-1 and 2007-8) data on suicidal behaviour reported by the Belgian Network of Sentinel General Practices (SGP), we describe trends in the key characteristics of suicidal events. We also examine patient age-related trends in the on-site attendance of sentinel general practitioners (GPs) as first professional caregivers following suicid...

Although the sophistication and flexibility of the statistical technology available to the data analyst have increased, some durable, simple principles remain valid. Hypothesis-driven analyses, which were anticipated and specified in the protocol, must still be kept separate and privileged relative to the important, but risky data mining made possible by modern computers. Analyses that have a f...