Premature twins on a neonatal intensive care unit

This paper presents observations of boy and girl twins on a neonatal intensive care unit, following them through from 10 days old to return home. The observer hypothesizes about the experience of the twins as they progress, based on detailed notes of their actions. The preoccupations of the parents are incorporated, as are reactions and interventions of staff. The place and possible functions of such observation by a child psychotherapist attached to such a unit are elaborated in the concluding section.     

Deformation twinning and plastic recovery in Cu/Ag nanolayers under uniaxial tensile straining

Molecular dynamics simulations of nanoscale multilayered Cu/Ag metals have been conducted under uniaxial tensile straining to elucidate the out-of-plane deformation behaviour relevant to tensile spallation experiments. In nanolayers with pristine architectures, plastic dissipation prior to crack nucleation is suppressed owing to the high hydrostatic tensile stress state. The presence of sources for micro-twinning partials, such as micro-cracks or columnar grain boundaries, result in abundant deformation twin lamellae across multiple Cu/Ag interlayers. Plastic recovery is observed during unloading of the nanolayers.     

The Journal of Positive Psychology – Reviewers for 2012

Optimism and pessimism are associated with important outcomes including health and depression. Yet it is unclear if these apparent polar opposites form a single dimension or reflect two distinct systems. The extent to which personality accounts for differences in optimism/pessimism is also controversial. Here, we addressed these questions in a genetically informative sample of 852 pairs of twins. Distinct genetic influences on optimism and pessimism were found. Significant family-level environment effects also emerged, accounting for much of the negative relationship between optimism and pessimism, as well as a link to neuroticism. A general positive genetics factor exerted significant links among both personality and life-orientation traits. Both optimism bias and pessimism also showed genetic variance distinct from all effects of personality and from each other.     

Indiscernible Persons

In this article I discuss identity and indiscernibility for person-stages and persons. Identity through time is not an identity relation (it is a unity relation). Identity is carefully distinguished from persistence. Identity is timeless and necessary. Person-stages are carefully distinguished from persons. Theories of personal persistence are not theories of identity for persons. I deal not with the persistence of persons through time but with the timeless and necessary identity and indiscernibility of persons. I argue that it is possible that there are non-identical but indiscernible temporally whole persons. I discuss the biographies of persons and develop the type or token distinction for persons. Twins in symmetrical or eternally recurrent universes are examples of indiscernible persons. I discuss temporal and modal branching, and I end with survival for person-tokens and eternity for person-types.     

Behavioral Genetics, Health, and Aging

A recurring observation from studies of health in the elderly is the pervasiveness of individual differences. For many health-related endpoints, total variation appears to increase across age group; however, few longitudinal studies have reported whether these age differences reflect true age-related changes. There are a growing number of twin studies of aging that provide some insight, at least cross-sectionally, into the nature of individual differences in health. Increases in total variance most often reflect increases in environmental sources of variance. Covariation among traits reflects both genetic and environmental mediation, dependent on the sex of the sample and the measures of interest. Co-twin control approaches have been successful in exploring the role of environmental influences as risk factors for poor health. The most serious limitation to these studies is the lack of longitudinal information to disentangle survival and selection effects from aging.     

A Population-Based Twin Study of Parentally Reported Tactile and Auditory Defensiveness in Young Children

  Some adults and children exhibit defensive behaviors to tactile or auditory stimulation. These symptoms occur not only in subsets of children with ADHD, autism, and Fragile X syndrome, but also in the apparent absence of accompanying disorders. Relatively little research explores the correlates and antecedents of sensory defensiveness. Using a population-based sample of 1,394 toddler-aged twins, mothers reported on tactile and auditory defensiveness, temperament, and behavior problems. The incidence of defensive symptoms was widely distributed, with some accumulation of cases in the extreme range. Girls were overrepresented in the extreme tactile defensiveness group. Both auditory and tactile defensiveness were modestly associated with fearful temperament and anxiety, but they were relatively distinct from other common dimensions of childhood behavioral dysfunction. Twin correlations for the full range of scores and concordance rates for the extremes suggested moderate genetic influences, with some indication that the tactile domain might be more heritable than the auditory domain.     

Genetic and environmental sources of continuity and change in teacher‐rated aggression during early adolescence

Genetic and environmental sources of continuity and change in aggression were studied in a sample of 1,041 twin pairs (364 monozygotic; 348 same‐sex dizygotic; and 329 opposite‐sex dizygotic) as part of an ongoing, population‐based Finnish twin‐family study. At ages 12 and 14, the twins' aggression was assessed by their classroom teachers, using a rating form of the Multidimensional Peer Nomination Inventory. Genetic and environmental sources of continuity and change were studied by fitting a longitudinal bivariate Cholesky decomposition model. Longitudinal model‐fitting results indicated that both genetic and environmental factors influenced continuity in aggression during this 2‐year period, but the age‐to‐age correlation of these factors differed by sex. Continuity in boys' aggression was mediated by genes and common environmental factors; in girls, in contrast, continuity was due primarily to common environmental, and to a lesser degree, unique environmental factors. Genes and unique environments contributed to change in aggression in both sexes. Aggr. Behav. 31:1–13, 2006. © 2006 Wiley‐Liss, Inc.     

What Causes Specific Language Impairment in Children?

ABSTRACT— Specific language impairment (SLI) is diagnosed when a child's language development is deficient for no obvious reason. For many years, there was a tendency to assume that SLI was caused by factors such as poor parenting, subtle brain damage around the time of birth, or transient hearing loss. Subsequently it became clear that these factors were far less important than genes in determining risk for SLI. A quest to find "the gene for SLI" was undertaken, but it soon became apparent that no single cause could account for all cases. Furthermore, although fascinating cases of SLI caused by a single mutation have been discovered, in most children the disorder has a more complex basis, with several genetic and environmental risk factors interacting. The clearest evidence for genetic effects has come from studies that diagnosed SLI using theoretically motivated measures of underlying cognitive deficits rather than conventional clinical criteria.     

Separation of conjoined twins and the principle of double effect.

This article examines the relationship between the principle of double effect and justification for separation surgeries for conjoined twins. First, the principle of double effect is examined in light of its historical context. It is argued that it can only operate under an absolutist view of good and evil that is compatible with the Bible. Given this foundation for application, scenarios for separating conjoined twins are considered against the criteria for the principle of double effect. It is concluded that the principle of double effect cannot be applied to cases wherein one of the twins must be killed. However, it is noted that this does not leave decision makers without options.