Perfect sampling algorithm for small <Emphasis Type="Italic">m</Emphasis>×<Emphasis Type="Italic">n</Emphasis> contingency tables

A Markov chain is proposed that uses coupling from the past sampling algorithm for sampling m×n contingency tables. This method is an extension of the one proposed by Kijima and Matsui (Rand. Struct. Alg., 29:243–256, 2006). It is not polynomial, as it is based upon a recursion, and includes a rejection phase but can be used for practical purposes on small contingency tables as illustrated in a classical 4×4 example.     

The Environmental Geochemistry and Bioaccessibility of Mercury in Soils and Sediments: A Review

There have been many studies of mercury geochemistry in the environment and its bioconcentration/bioaccumulation through the aquatic food chain. However, there is a dearth of information regarding the bioaccessibility of mercury in human receptors exposed primarily by soil ingestion. This paper reviews the current state of knowledge of mercury bioaccessibility and speciation in soils, and the utility of speciation methods to estimate mercury bioaccessibility. We conclude that additional research is necessary to determine: (1) whether analytical measurements can adequately determine the bioaccessibility of mercury in sediments and soils; (2) the accuracy of in vitro analyses in assessing mercury bioaccessibility; (3) the ability of mercury to cross tissue membranes of the mouth, esophagus, stomach, and the small and large intestines; (4) the speciation and distribution of mercury in biological fluids; and (5) mercury bioavailability using an in vivo animal model relevant to human gastrointestinal tract conditions.     

Effects of sleep inertia on cognitive performance following a 1-hour nap

This study investigated the effects of a 1-h nap on subsequent performance in spatial memory (SM) and logical reasoning (LR) tasks. The objective was to evaluate the duration of the effects of sleep inertia (SI). The performance was measured in two independent groups of subjects. The 1-h nap took place at 00:00 h in group 1 and at 03:00 h in group 2. In each task, the experimental design comprised one no-nap condition in which subjects had no sleep before the night tests, and a nap condition that comprised the 1-h nap followed by the test sessions. To measure the duration of SI effects, the subjects were tested in two 30-min sessions and the data in each session were analysed in sub-units of time of 3 min each. In each task the results showed no effects on accuracy, and no circadian effects of napping were found. In each task, analyses of pooled data of the two groups showed that the performance in the 1-h nap condition exhibited significant reductions of speed immediately following awakening, when compared with no-nap, reflecting SI effects. In SM, the slowing lasted 24 min, and 27 min in LR. Practical implications of the results are discussed.     

Decision-Making Under Scientific Uncertainty: The Economics of the Precautionary Principle

The Precautionary Principle has provided the foundations for building a new risk regulatory pattern under scientific uncertainty. This paper investigates how classical economic theory may, or may not, justify the Precautionary Principle. It examines the link between irreversibility, the prospect of increasing information over time and risk management. In doing so, it brings closer the notion of option value to that of precaution. Using a general modelling framework, it identifies the conditions so that the Precautionary Principle is an efficient economic guideline. It also explains why precautionary policies are not likely to emerge in a competitive economy or in the presence of a global pollution problem.     

Socio‐Emotional Context and Adolescents' Decision Making: The Experience of Regret and Relief After Social Comparison

Many studies indicate that adolescents are hypersensitive to rewards in salient socio‐emotional contexts. However, little is known about adolescents' sensitivity to complex negative emotions. To study the development of the ability to experience regret and relief, children, adolescents, and young adults performed a gambling task in a socio‐emotional context of competition, in which they were informed that their outcome would be compared with that of a competitor. The context of competition impacted the feelings of regret and relief in adolescents. When adolescents experienced an initial negative outcome, their feeling of relief was reinforced. However, they did not seem to experience regret in the social context of competition. These results provide a possible explanation for adolescents' enhanced risk seeking.     

INFORMATION THROUGH SAMPLING FROM A BINOMIAL DISTRIBUTION*

Lindley's measure of experimental information is utilized to determine the optimal sample-size that is required to obtain a prescribed level of accuracy about the parameter of a binomial distribution. The measure is expressed through its approximate limiting relationship to the posterior variance of the parameter, and a simple application of the methodology is presented.     

The influence of the COVID-19 lockdown on infants' physiological regulation during mother-father-infant interactions in Switzerland

In this study, we investigated the physiological regulation of vagal tone during dyadic and triadic parent-infant interactions in infants born before or around the COVID-19 lockdown in Switzerland. We hypothesized that there would be a decrease in vagal tone in triadic interactions compared with dyadic interactions, as triadic interactions are more complex and therefore more resource demanding. However, we expected this difference to be smaller for infants who experienced the period of confinement, as the lockdown led parents to spend more time at home. We also hypothesized that parents would have less stressful interactional events in the triadic interaction because they would be used to interacting with the child together. This study included 36 parents with their 3 month-old infants. Eighteen families met the study authors before the onset of the pandemic (pre-COVID) and 18 met them after its onset, having experienced a period of confinement during the infants' first 3 months of life (COVID). Results showed that the COVID group had no decrease in vagal tone during triadic interactions, whereas the pre-COVID group did. This difference could not, however, be explained by less stressful interactional events in triadic interactions, as the COVID group showed more stressful interactional events in mother-father-infant interactions.     

CREDIT CONSTRAINTS AND THE CYCLICALITY OF R&D INVESTMENT: EVIDENCE FROM FRANCE

We use a French firm‐level data set containing 13,000 firms over the period 1994–2004 to analyze the relationship between credit constraints and firms’ R&D behavior over the business cycle. Our main results can be summarized as follows: (i) R&D investment is countercyclical without credit constraints, but it becomes procyclical as firms face tighter credit constraints; (ii) this result is only observed for firms in sectors that depend more heavily upon external finance, or that are characterized by a low degree of asset tangibility; (iii) in more credit‐constrained firms, R&D investment plummets during recessions but does not increase proportionally during upturns.