The effects of supernovae on the dynamical evolution of binary stars and star clusters

In this chapter I review the effects of supernovae explosions on the dynamical evolution of (1) binary stars and (2) star clusters. (1) Supernovae in binaries can drastically alter the orbit of the system, sometimes disrupting it entirely, and are thought to be partially responsible for `runaway' massive stars - stars in the Galaxy with large peculiar velocities. The ejection of the lower-mass secondary component of a binary occurs often in the event of the more massive primary star exploding as a supernova. The orbital properties of binaries that contain massive stars mean that the observed velocities of runaway stars (10s - 100s km s$^{-1}$) are consistent with this scenario. (2) Star formation is an inherently inefficient process, and much of the potential in young star clusters remains in the form of gas. Supernovae can in principle expel this gas, which would drastically alter the dynamics of the cluster by unbinding the stars from the potential. However, recent numerical simulations, and observational evidence that gas-free clusters are observed to be bound, suggest that the effects of supernova explosions on the dynamics of star clusters are likely to be minimal.Comment: 16 pages, to appear in the 'Handbook of Supernovae', eds. Paul Murdin and Athem Alsabti. This version replaces an earlier version that contained several typo

Incidence and duration of total occlusion of the radial artery in newborn infants after catheter removal

The incidence and duration of total occlusion of the radial artery after catheter removal was determined using repeated Doppler flow measurements. Thirty-two newborn infants with birthweights ranging from 945 g to 3890 g (median 1935 g) and gestational age ranging from 26 to 40 weeks (median 32 weeks) were studied. In 20 out of 32 infants (63%), complete occlusion of the radial artery occurred. The number of occlusions were not related to birthweight, gestational age or duration of cannulation. In all infants, blood flow in the radial artery resumed within 1-29 days after catheter removal. The duration of occlusion was directly related to the duration of cannulation and inversely related to birthweight. This study demonstrates a high frequency of total occlusion of the radial artery in newborn infants after percutaneous radial artery cannulation. In the majority of infants with a radial artert catheter, blood flow to the tissue distal to the cannulation site is dependent solely on the existence of an adequate arterial palmar collateral circulation

Registration of cancer in girls remains lower than expected in countries with low/middle incomes and low female education rates.

BACKGROUND: A decade ago it was reported that childhood cancer incidence was higher in boys than girls in many countries, particularly those with low gross domestic product (GDP) and high infant mortality rate. Research suggests that socio-economic and cultural factors are likely to be responsible. This study aimed to investigate the association between cancer registration rate sex ratios and economic, social and healthcare-related factors using recent data (1998-2002). METHODS: For 62 countries, childhood (0-15 years) cancer registration rate sex ratios were calculated from Cancer Incidence in Five Continents Vol IX, and economic, social and healthcare indicator data were collated. RESULTS: Increased age standardised cancer registration rate sex ratio (M:F) was significantly associated with decreasing life expectancy (P=0.05), physician density (P=0.05), per capita health expenditure (P=0.05), GDP (P=0.01), education sex ratios (primary school enrolment sex ratio (P<0.01); secondary school enrolment sex ratio (P<0.01); adult literacy sex ratio (P<0.01)) and increasing proportion living on less than Int$1 per day (P=0.03). CONCLUSION: The previously described cancer registration sex disparity remains, particularly, in countries with poor health system indicators and low female education rates. We suggest that girls with cancer continue to go undiagnosed and that incidence data, particularly in low- and middle-income countries, should continue to be interpreted with caution

Shared cognition in childhood anxiety: interpretation bias in preschool children and their parents

Although interpretation bias has been associated with the development and/or maintenance of childhood anxiety, its origins remain unclear. The present study is the first to examine intergenerational transmission of this bias from parents to their preschool-aged children via the verbal information pathway. A community sample of fifty parent–child pairs was recruited. Parents completed measures of their own trait anxiety and interpretation bias, their child’s anxiety symptoms, and a written story-stem measure, to capture the way parents tell their children stories. Interpretation bias was assessed in preschool-aged children (aged between 2 years 7 months and 5 years 8 months) using an extended story-stem paradigm. Young children’s interpretation bias was not significantly associated with their own anxiety symptoms. Neither was there evidence for a significant association between parent and child interpretation bias. However, parents who reported they would tell their child one or more threatening story endings in the written story-stem task had significantly higher anxiety than those who did not include any threatening story endings. In turn, children whose parents did not include any threatening endings in their written stories had significantly lower threat interpretations on the child story-stem paradigm, compared to those with parents who included at least one threatening story ending. The results suggest that parental verbal information could play a role in the development of interpretation bias in young children

The Evolution of Compact Binary Star Systems

We review the formation and evolution of compact binary stars consisting of white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). Binary NSs and BHs are thought to be the primary astrophysical sources of gravitational waves (GWs) within the frequency band of ground-based detectors, while compact binaries of WDs are important sources of GWs at lower frequencies to be covered by space interferometers (LISA). Major uncertainties in the current understanding of properties of NSs and BHs most relevant to the GW studies are discussed, including the treatment of the natal kicks which compact stellar remnants acquire during the core collapse of massive stars and the common envelope phase of binary evolution. We discuss the coalescence rates of binary NSs and BHs and prospects for their detections, the formation and evolution of binary WDs and their observational manifestations. Special attention is given to AM CVn-stars -- compact binaries in which the Roche lobe is filled by another WD or a low-mass partially degenerate helium-star, as these stars are thought to be the best LISA verification binary GW sources.Comment: 105 pages, 18 figure

Motives and comprehension in a public goods game with induced emotions

This study analyses the sensitivity of public goods contributions through the lens of psychological motives. We report the results of a public goods experiment in which subjects were induced with the motives of care and anger through autobiographical recall. Subjects' preferences, beliefs, and perceptions under each motive are compared with those of subjects experiencing a neutral autobiographical recall control condition. We find, but only for those subjects with the highest comprehension of the game, that care elicits significantly higher contributions than anger, with the control treatment in between. This positive influence of the care motive on unconditional giving is accounted for partly by preferences for giving and partly by the beliefs concerning greater contributions by others. Anger also affects attention to own and other's payoffs (using mouse tracking) and perceptions of the game's incentive structure (cooperative or competitive)

Allergic conditions and risk of hematological malignancies in adults: a cohort study

BACKGROUND: Two contradictory hypotheses have been proposed to explain the relationship between allergic conditions and malignancies, the immune surveillance hypothesis and the antigenic stimulation hypothesis. The former advocates that allergic conditions may be protective against development of cancer, whereas the latter proposes an increased risk. This relationship has been studied in several case-control studies, but only in a few cohort studies. METHODS: The association between allergic conditions and risk of developing leukemia, Hodgkin's disease, non-Hodgkin's lymphoma and myeloma was investigated in a cohort of 16,539 Swedish twins born 1886–1925. Prospectively collected, self-reported information about allergic conditions such as asthma, hay fever or eczema was obtained through questionnaires administered in 1967. The cohort was followed 1969–99 and cancer incidence was ascertained from the Swedish Cancer Registry. RESULTS: Hives and asthma tended to increase the risk of leukemia (relative risk [RR] = 2.1, 95% Confidence Interval [CI] 1.0–4.5 and RR = 1.6, 95% CI 0.8–3.5, respectively). There was also an indication of an increased risk of non-Hodgkin's lymphoma associated with eczema during childhood (RR = 2.3, 95% CI 1.0–5.3). CONCLUSION: In contrast to most previous studies, our results do not indicate a protective effect of allergic conditions on the risk of developing hematological malignancies. Rather, they suggest that allergic conditions might increase the risk of some hematological malignancies

Drawing nature of science in pre-service science teacher education: Epistemic insight through visual representations

Developing pre-service science teachers’ epistemic insight remains a challenge, despite decades of research in related bodies of work such as the nature of science (NOS) in science education. While there may be numerous aspects to this problem, one critical element is that the NOS is a meta-concept that demands higher-order cognitive skills. One possible strategy to facilitate pre-service teachers’ understanding of epistemic aspects of science is visualisation. Visual representations of objects and processes can be tools for developing and monitoring understanding. Although the NOS and visualisation literatures have been studied extensively, the intersection of these bodies of literatures has been minimal. Incorporating visual tools on the NOS in teacher education is likely to facilitate teachers’ learning, eventually impacting their students’ learning of the NOS. The objective of this paper is to illustrate how the visual tools of scientific knowledge and practices aspects of the NOS can be integrated in science teacher education in order to develop pre-service teachers’ epistemic insight. The paper presents an empirical study that incorporated visual tools about the NOS in primary science teacher education. Data on 14 pre-service teachers’ are presented along with in-depth case studies of 3 pre-service teachers illustrating the influence of the teacher education intervention. The qualitative analysis of visual representations before and after the intervention as well as verbal data suggests that there was improvement in pre-service teachers’ perceptions of the NOS. Implications for future research on visualisation of the NOS are discussed