Phase transition in the globalization of trade

Globalization processes interweave economic structures at a worldwide scale, trade playing a central role as one of the elemental channels of interaction among countries. Despite the significance of such phenomena, measuring economic globalization still remains an open problem. More quantitative treatments could improve the understanding of globalization at the same time that help a formal basis for comparative economic history. In this letter, we investigate the time evolution of the statistical properties of bilateral trade imbalances between countries in the trade system. We measure their cumulative probability distribution at different moments in time to discover a sudden transition circa 1960 from a regime where the distribution was always represented by a steady characteristic function to a new state where the distribution dilates as time goes on. This suggests that the rule that was governing the statistical behavior of bilateral trade imbalances until the 60's abruptly changed to a new form persistent in the last decades. In the new regime, the figures for the different years collapse into a universal master curve when rescaled by the corresponding global gross domestic product value. This coupling points to an increased interdependence of world economies and its onset corresponds in time with the starting of the last globalization wave.Comment: Final versio

Epidemiology of Concussive Injuries in Collegiate Recreational Athletics

Background: The epidemiology of concussion in collegiate and high school athletes has been extensively researched. Concussive injury in collegiate recreation, a less supervised sample, is limited. This preliminary study retrospectively examined the incidence and prevalence rates of concussive injuries in intramural and club sports at one institution. Methods: Injury reports were analyzed during the 2016-2019 calendar years. Concussion prevalence, incidence, and odds ratios (reported with 95% CIs) were calculated for intramural and club sports. Results: During the study period, a total of 805 injuries were reported between intramural and club sports with 111 injuries being documented as concussions. Intramural sports concussion prevalence averaged a rate of 2.77 per 1,000 unique participants while the incidence for both intramural and club sports was 13.79%. Females (2.58; 95% CI, 1.623-3.722), club lacrosse (8.923; 95% CI, 0.906-87.84), and club ultimate frisbee (7.83; 95% CI, 1.02-60.114) resulted in having higher odds of sustaining a concussion. Conclusion: Concussion prevalence and incidence was higher in this sample compared to high school and NCAA athletes. The high incidence of concussion paired with lack of medical care may result in poor outcomes in this population. Future research should replicate and expand to ensure increased rates are generalizable

The effect of a planet on the dust distribution in a 3D protoplanetary disk

Aims: We investigate the behaviour of dust in protoplanetary disks under the action of gas drag in the presence of a planet. Our goal is twofold: to determine the spatial distribution of dust depending on grain size and planet mass, and therefore to provide a framework for interpretation of coming observations and future studies of planetesimal growth. Method: We numerically model the evolution of dust in a protoplanetary disk using a two-fluid (gas + dust) Smoothed Particle Hydrodynamics (SPH) code, which is non-self-gravitating and locally isothermal. The code follows the three dimensional distribution of dust in a protoplanetary disk as it interacts with the gas via aerodynamic drag. In this work, we present the evolution of a minimum mass solar nebula (MMSN) disk comprising 1% dust by mass in the presence of an embedded planet. We run a series of simulations which vary the grain size and planetary mass to see how they affect the resulting disk structure. Results: We find that gap formation is much more rapid and striking in the dust layer than in the gaseous disk and that a system with a given stellar, disk and planetary mass will have a completely different appearance depending on the grain size. For low mass planets in our MMSN disk, a gap can open in the dust disk while not in the gas disk. We also note that dust accumulates at the external edge of the planetary gap and speculate that the presence of a planet in the disk may enhance the formation of a second planet by facilitating the growth of planetesimals in this high density region.Comment: 13 pages, 12 figures. Accepted for publication in Astronomy & Astrophysic

Predicting Dust Distribution in Protoplanetary Discs

We present the results of three-dimensional numerical simulations that include the effects of hydrodynamical forces and gas drag upon an evolving dusty gas disk. We briefly describe a new parallel, two phase numerical code based upon the smoothed particle hydrodynamics (SPH) technique in which the gas and dust phases are represented by two distinct types of particles. We use the code to follow the dynamical evolution of a population of grains in a gaseous protoplanetary disk in order to understand the distribution of grains of different sizes within the disk. Our ``grains'' range from metre to submillimetre in size.Comment: 2 pages, LaTeX with 1 ps figure embedded, using newpasp.sty (supplied). To appear in the proceedings of the XIXth IAP colloquium "Extrasolar Planets: Today and Tomorrow" held in Paris, France, 2003, June 30 -- July 4, ASP Conf. Se

Rapid faecal transmission and invasive amoebiasis in Durban

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Does sleep education change sleep parameters? Comparing sleep education trials for middle school students in Australia and New Zealand

Background: Adolescents suffer daytime consequences from sleep loss. Sleep education programs have been developed in an attempt to increase sleep knowledge and/or duration. This paper presents data from three trials of the Aus-tralian Centre for Education in Sleep (ACES) program for adolescents.Methods: The ACES program was delivered to 69 Australian adolescents in a pre-post cross-sectional design (mean age 15.2) and 29 New Zealand adolescents in a randomised control trial (mean age 14.8 years). Assessments in sleep parame-ters were undertaken at baseline and post intervention.Results: Where sleep knowledge was evaluated (Australian trials), significant improvements were shown in all trials (All p <0.05). Where sleep duration was assessed (New Zealand trial) significant improvements were found in week and weekend sleep duration [F(1, 27)=4.26, p=0.04). Both, students and teachers found the program feasible, interesting, and educational.Conclusions: ACES sleep education programmes can improve both sleep knowledge and sleep duration in adolescents. Improving the programme so sleep knowledge attained equates to actual sleep behaviour change are areas for future direc-tion. Collectively these findings provide encouraging signs that adolescents can improve their sleep knowledge and behav-iour with sleep education which bodes well for sleep-related health and psycho-social issues

Getting active with active video games: A quasi-experimental study

Given the cultural emphasis on academic achievement and environmental constraints to physical activity (PA), active video games (AVGs) may be used to decrease sedentary behavior and increase PA of Hong Kong children. This study explored the potential of a school-based AVG intervention on sedentary time, PA, body composition, and psychosocial factors among children. Eighty-seven children (intervention n = 30) were recruited from one primary school. Classes in Grades 4–6 were allocated to either the intervention group or the control group in a 2:1 ratio. The eight-week intervention involved children playing AVGs in an after-school class twice a week. Participants in the control group continued with their usual activities. Outcome included the change of participants in sedentary time, PA, percentage body fat, body mass index (BMI), and psychosocial variables (enjoyment, self-efficacy and social support), from baseline to eight weeks. No significant group differences were observed in sedentary time (−33.9 min/day, 95% CI −70.8 to 4.8; p = 0.07). The intervention group significantly increased total PA (53.7 counts/min, 95% CI 8.6 to 104.2; p = 0.04) compared with those in the control condition. No differences were found in body composition and psychosocial variables. However, significant treatment effects were found on BMI z score among boys (−0.1, 95% CI −0.2 to 0; p = 0.04). An eight-week school-based AVG intervention delivered during after-school hours was effective in increasing activity levels among Hong Kong children. The treatment effects of AVGs on sedentary behavior and body composition need to be further demonstrated in a more robust study, especially in boys

SPH simulations of accretion disks and narrow rings

We model a massless viscous disk using Smoothed Particle Hydrodynamics (SPH) and note that it evolves according to the Lynden-Bell \& Pringle theory (1974) until a non-axisymmetric instability develops at the inner edge of the disk. This instability may have the same origin as the instability of initially axisymmetric viscous disks discussed by Lyubarskij et al. (1994). To clarify the evolution we evolved single and double rings of particles. It is actually inconsistent with the SPH scheme to set up a single ring as an initial condition because SPH assumes a smoothed initial state. As would be expected from an SPH simulation, the ring rapidly breaks up into a band. We analyse the stability of the ring and show that the predictions are confirmed by the simulation