The Formation Rate of Blue Stragglers in 47 Tucanae

We investigate the effects of changes in the blue straggler formation rate in globular clusters on the blue straggler distribution in the color-magnitude diagram. We find that the blue straggler distribution is highly sensitive to the past formation rate. Comparing our models to new UBV observations of a region close to the core of 47 Tucanae suggests that this cluster may have stopped forming blue straggler formation several Gyr ago. This cessation of formation can be associated with an epoch of primordial binary burning which has been invoked in other clusters to infer the imminence of core collapse.Comment: 17 pages, 9 figures, submitted to the Astrophysical Journa

Parental stress increases body mass index trajectory in pre-adolescents.

What is already known about this subjectRates of childhood obesity have increased since the mid-1970s. Research into behavioural determinants has focused on physical inactivity and unhealthy diets. Cross-sectional studies indicate an association between psychological stress experienced by parents and obesity in pre-adolescents.What this study addsWe provide evidence of a prospective association between parental psychological stress and increased weight gain in pre-adolescents. Family-level support for those experiencing chronic stress might help promote healthy diet and exercise behaviours in children.ObjectiveWe examined the impact of parental psychological stress on body mass index (BMI) in pre-adolescent children over 4 years of follow-up.MethodsWe included 4078 children aged 5-10 years (90% were between 5.5 and 7.5 years) at study entry (2002-2003) in the Children's Health Study, a prospective cohort study in southern California. A multi-level linear model simultaneously examined the effect of parental stress at study entry on the attained BMI at age 10 and the slope of change across annual measures of BMI during follow-up, controlled for the child's age and sex. BMI was calculated based on objective measurements of height and weight by trained technicians following a standardized procedure.ResultsA two standard deviation increase in parental stress at study entry was associated with an increase in predicted BMI attained by age 10 of 0.287 kg m(-2) (95% confidence interval 0.016-0.558; a 2% increase at this age for a participant of average attained BMI). The same increase in parental stress was also associated with an increased trajectory of weight gain over follow-up, with the slope of change in BMI increased by 0.054 kg m(-2) (95% confidence interval 0.007-0.100; a 7% increase in the slope of change for a participant of average BMI trajectory).ConclusionsWe prospectively demonstrated a small effect of parental stress on BMI at age 10 and weight gain earlier in life than reported previously. Interventions to address the burden of childhood obesity should address the role of parental stress in children

Hubble Space Telescope times-series photometry of the planetary transit of HD189733: no moon, no rings, starspots

We monitored three transits of the giant gas planet around the nearby K dwarf HD 189733 with the ACS camera on the Hubble Space Telescope. The resulting very-high accuracy lightcurve (signal-to-noise ratio near 15000 on individual measurements, 35000 on 10-minute averages) allows a direct geometric measurement of the orbital inclination, radius ratio and scale of the system: i = 85.68 +- 0.04, Rpl/R*=0.1572 +- 0.0004, a/R*=8.92 +- 0.09. We derive improved values for the stellar and planetary radius, R*=0.755+- 0.011 Rsol, Rpl=1.154 +- 0.017 RJ, and the transit ephemerides, Ttr=2453931.12048 +- 0.00002 + n 2.218581 +- 0.000002$. The HST data also reveal clear evidence of the planet occulting spots on the surface of the star. At least one large spot complex (>80000 km) is required to explain the observed flux residuals and their colour evolution. This feature is compatible in amplitude and phase with the variability observed simultaneously from the ground. No evidence for satellites or rings around HD 189733b is seen in the HST lightcurve. This allows us to exlude with a high probability the presence of Earth-sized moons and Saturn-type debris rings around this planet. The timing of the three transits sampled is stable to the level of a few seconds, excluding a massive second planet in outer 2:1 resonance.Comment: revised version. Significant updates and new figures; to appear in Astronomy and Astrophysic

Understanding child and parent perceptions of barriers influencing children’s active school travel

Background Physical activity plays a fundamental role in the health and well-being of children. Walking is the most common form of physical activity and the journey to and from school provides an opportunity for children to be active every day. This study examines how child and parent perceptions of barriers to active school travel influences children’s behaviour. Methods Participants were recruited from 48 elementary schools in Southwestern Ontario, Canada. The study sample includes 1296 children (ages 9–14 years) who live within walking distance of their school, defined as 1.6 km network distance. Chi-square analysis examined differences between child and parent perceptions of barriers to active school travel. Logistic regression models examined how parent and child perceptions of barriers influence active school travel behaviour, while controlling for key intrapersonal, interpersonal, and physical environment factors. Results The results indicate that there are significant differences in how parents and children perceive barriers to active school travel. Model results find older children, children without siblings, households with no vehicles, and children who live closer to school are most likely to use active school travel. Parent perceptions of barriers are found to have a greater influence on children’s active school travel behaviour than children’s perceptions. Different perceptions of barriers influence active school travel to school compared to returning home from school. Conclusions Child and parent perceptions of barriers to active school travel differ and have different impacts on children’s travel behaviour. Understanding how child and parent perceptions of barriers differ can help policymakers and practitioners develop specialized interventions aimed at increasing children’s use of active school travel and children’s overall physical activity. Interventions used to promote active school travel should focus on safety, as well as perceptions of distance to break parental habits of routinely driving their children to school. Overall, this study highlights the importance of considering both child and parent perceptions to create a safe and accessible environment to allow for an increase in active school travel behaviour among elementary school children who live within walking distance of their school

Sigmoid gallstone ileus: a challenging diagnosis

Gallstone ileus is a rare (1%–4%) complication of gallstone disease. Gallstones entering the gastrointestinal tract by penetration may cause obstruction at any point along their course through the tract; however, they have a predilection to obstruct the smaller-caliber lumen of the small intestine (80.1%) or stomach (14.2%). The condition is seen more commonly in the elderly who often have significant co-morbidities. Gallstone ileus causing large bowel obstruction is rare. We report the case of a 95-year-old woman who presented with a history of abdominal pain without fever, nausea, vomiting, or diarrhea. Computed tomography of the abdomen and pelvis with oral contrast revealed a high-density structure within the lumen of the distal sigmoid colon, initially suspected to be a foreign body. Medical management failed and surgical intervention was not possible. Autopsy revealed peritonitis and a rupture of the sigmoid colon at the site of a cylindrical stone found impacted in an area of fibrotic narrowing with multiple diverticula. A necrotic, thick-walled gallbladder had an irregular stone in its lumen that was a fracture match with the stone in the sigmoid. Adhesions, but no discrete fistula, were identified between the gallbladder and the adjacent transverse colon. The immediate cause of death was peritonitis caused by colonic perforation by the gallstone impacted at an area of diverticular narrowing. To our knowledge, such autopsy findings have not been previously reported

High Redshift Supernovae in the Hubble Deep Field

Two supernovae detected in the Hubble Deep Field using the original December 1995 epoch and data from a shorter (63000 s in F814W) December 1997 visit with HST are discussed. The supernovae (SNe) are both associated with distinct galaxies at redshifts of 0.95 (spectroscopic) from Cohen etal. (1996) and 1.32 (photometric) from the work of Fernandez-Soto, Lanzetta, and Yahil (1998). These redshifts are near, in the case of 0.95, and well beyond for 1.32 the greatest distance reported previously for SNe. We show that our observations are sensitive to SNe to z < 1.8 in either epoch for an event near peak brightness. Detailed simulations are discussed that quantify the level at which false events from our search phase would start to to arise, and the completeness of our search as a function of both SN brightness and host galaxy redshift. The number of Type Ia and Type II SNe expected as a function of redshift in the two HDF epochs are discussed in relation to several published predictions and our own detailed calculations. A mean detection frequency of one SN per epoch for the small HDF area is consistent with expectations from current theory.Comment: 62 pages, 17 figures, ApJ 1999 in pres

Understanding factors associated with children achieving recommended amount of MVPA on weekdays and weekend days

Low levels of moderate-to-vigorous physical activity (MVPA) are consistently reported for children from industrialized countries. Perennially inadequate levels of MVPA have been linked to increased chronic disease risks. Very few studies have compared physical activity levels among children from geographically diverse places, and how they differ on weekdays versus weekends. The purpose of this research is to examine the factors that influence whether children achieve 60 min of MVPA on weekdays compared to weekend days. Data were analyzed on children (n = 532) aged 8–14 years from communities in Southern and Northern Ontario, Canada that participated in the study between 2009 and 2016. Children\u27s MVPA was measured using an Actical accelerometer, environmental features measured with a geographic information system, and demographic data came from child/parent surveys. Variables were selected using a least absolute shrinkage and selection operator. The variables were entered into logistic regression models to assess the relationship between children meeting the MVPA guidelines. During the week, boys were more active than girls (OR = 4.652 p \u3c 0.001) and as age increased children were less likely to reach the MVPA guidelines (OR = 0.758 p = 0.013). On weekends boys were still more likely to meet the guidelines (OR = 1.683 p = 0.014) and children living in rural Northern Ontario were more likely to reach the MVPA guidelines compared to all groups in Southern Ontario. The findings indicate that different variables influence whether children meet the MVPA guidelines on weekdays compared to weekends. Comparing weekdays and weekends provides more useful information for creating effective MVPA interventions