We use cookies to distinguish you from other users and to provide you with a better experience on our websites. Close this message to accept cookies or find out how to manage your cookie settings.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to .
To save content items to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Find out more about the Kindle Personal Document Service.
We describe an algorithm that can fit the properties of the dwarf galaxy progenitor of a tidal stream, given the properties of that stream. We show that under ideal conditions (the Milky Way potential, the orbit of the dwarf galaxy progenitor, and the functional form of the dwarf galaxy progenitor are known exactly), the density and angular width of stars along the stream can be used to constrain the mass and radial profile of both the stellar and dark matter components of the progenitor dwarf galaxy that was ripped apart to create the stream. Our provisional fit for the parameters of the dwarf galaxy progenitor of the Orphan Stream indicates that it is less massive and has fewer stars than previous works have indicated.
Early institutional rearing is associated with increased risk for subsequent peer relationship difficulties, but the underlying mechanisms have not been identified. Friendship characteristics, social behaviors with peers, normed assessments of social problems, and social cue use were assessed in 142 children (mean age = 10.06, SD = 2.02; range 7–13 years), of whom 67 were previously institutionalized (PI), and 75 were raised by their biological families. Anxiety and attention-deficit/hyperactivity disorder (ADHD) symptoms, often elevated among PI children, were examined as potential mediators of PI status and baseline social functioning and longitudinal follow-ups (2 and 4 years later). Twenty-seven percent of PI children fell above the Child Behavior Checklist Social Problems cutoff. An examination of specific social behaviors with peers indicated that PI and comparison children did not differ in empathic concern or peer social approach, though parents were more likely to endorse aggression/overarousal as a reason that PI children might struggle with friendships. Comparison children outperformed PI children in computerized testing of social cue use learning. Finally, across these measures, social difficulties exhibited in the PI group were mediated by ADHD symptoms with predicted social problems assessed 4 years later. These findings show that, when PI children struggle with friendships, mechanisms involving attention and behavior regulation are likely contributors.
Childhood maltreatment robustly predicts adolescent externalizing behaviors (EB; e.g., violence, delinquency, substance use) and may crystalize patterns of EB by influencing sensitivity to the social environment (e.g., parenting, friendships). In a nationally representative sample of 9,421 adolescents, we modeled latent growth curves of EB from age 13 to 32 years. Next, we explored whether maltreated youth differed from nonmaltreated youth in their sensitivity to parental closeness, friendship involvement, and polymorphisms from dopamine genes linked to EB (dopamine receptors D2 and D4, dopamine transporter). Overall, maltreated youth had significantly higher levels of EB across adolescence and adulthood; however, maltreated and nonmaltreated youth showed similar patterns of EB change over time: violent behavior decreased in adolescence before stabilizing in adulthood, whereas nonviolent delinquency and substance use increased in adolescence before decreasing in the transition to adulthood. Maltreatment reduced sensitivity to parental closeness and friendship involvement, although patterns varied based on type of EB outcome. Finally, none of the environmental effects on EB were significantly moderated by the dopamine polygenic risk score after accounting for multiple testing. These findings underline the enduring effects of early maltreatment and implicate that maltreatment may contribute to long-term risk for EB by influencing children's sensitivity to social relationship factors in adolescence.
Although prevailing theories of antisocial behavior (ASB) emphasize distinct developmental trajectories, few studies have explored gene–environment interplay underlying membership in empirically derived trajectories. To improve knowledge about the development of overt (e.g., aggression) and covert (e.g., delinquency) ASB, we tested the association of the 44-base pair promoter polymorphism in the serotonin transporter linked polymorphic region gene (5-HTTLPR), perceived parental support (e.g., closeness and warmth), and their interaction with ASB trajectories derived using latent class growth analysis in 2,558 adolescents followed prospectively into adulthood from the National Longitudinal Study of Adolescent Health. Three distinct trajectories emerged for overt (low desisting, adolescent peak, and late onset) and covert ASB (high stable, low stable, and nonoffending). Controlling for sex, parental support inversely predicted membership in the adolescent-peak overt ASB trajectory (vs. low desisting), but was unrelated to class membership for covert ASB. Furthermore, the 5-HTTLPR genotype significantly moderated the association of parental support on overt ASB trajectory membership. It is interesting that the pattern of Gene × Environment interaction differed by trajectory class: whereas short allele carriers were more sensitive to parental support in predicting the late-onset trajectory, the long/long genotype functioned as a potential “plasticity genotype” for the adolescent-peak trajectory group. We discuss these preliminary findings in the context of the differential susceptibility hypothesis and discuss the need for future studies to integrate gene–environment interplay and prospective longitudinal designs.
Although family support reliably predicts the development of adolescent depression and suicidal behaviors, relatively little is known about the interplay of family support with potential genetic factors. We tested the association of the 44 base pair polymorphism in the serotonin transporter linked promoter region gene (5-HTTLPR), family support (i.e., cohesion, communication, and warmth), and their interaction with self-reported depression symptoms and risk for suicide in 1,030 Caucasian adolescents and young adults from the National Longitudinal Study of Adolescent Health. High-quality family support predicted fewer symptoms of depression and reduced risk for suicidality. There was also a significant interaction between 5-HTTLPR and family support for boys and a marginally significant interaction for girls. Among boys with poor family support, youth with at least one short allele had more symptoms of depression and a higher risk for suicide attempts relative to boys homozygous for the long allele. However, in the presence of high family support, boys with the short allele had the fewest depression symptoms (but not suicide attempts). Results suggest that the short allele may increase reactivity to both negative and positive family influences in the development of depression. We discuss the potential role of interactive exchanges between family support and offspring genotype in the development of adolescent depression and suicidal behaviors.
The science of extra-solar planets is one of the most rapidly changing areas of astrophysics and since 1995 the number of planets known has increased by almost two orders of magnitude. A combination of ground-based surveys and dedicated space missions has resulted in 560-plus planets being detected, and over 1200 that await confirmation. NASA's Kepler mission has opened up the possibility of discovering Earth-like planets in the habitable zone around some of the 100,000 stars it is surveying during its 3 to 4-year lifetime. The new ESA's Gaia mission is expected to discover thousands of new planets around stars within 200 parsecs of the Sun. The key challenge now is moving on from discovery, important though that remains, to characterisation: what are these planets actually like, and why are they as they are?
In the past ten years, we have learned how to obtain the first spectra of exoplanets using transit transmission and emission spectroscopy. With the high stability of Spitzer, Hubble, and large ground-based telescopes the spectra of bright close-in massive planets can be obtained and species like water vapour, methane, carbon monoxide and dioxide have been detected. With transit science came the first tangible remote sensing of these planetary bodies and so one can start to extrapolate from what has been learnt from Solar System probes to what one might plan to learn about their faraway siblings. As we learn more about the atmospheres, surfaces and near-surfaces of these remote bodies, we will begin to build up a clearer picture of their construction, history and suitability for life.
The Exoplanet Characterisation Observatory, EChO, will be the first dedicated mission to investigate the physics and chemistry of Exoplanetary Atmospheres. By characterising spectroscopically more bodies in different environments we will take detailed planetology out of the Solar System and into the Galaxy as a whole.
EChO has now been selected by the European Space Agency to be assessed as one of four M3 mission candidates.