The prevalence of childhood obesity is increasing at an alarming rate. Many local governments have enacted policies to increase physical activity in schools as a way to combat childhood obesity. We ...conducted a systematic review and meta-analysis to determine the effect of school-based physical activity interventions on body mass index (BMI) in children.
We searched MEDLINE, EMBASE, CINAHL and the Cochrane Central Register of Controlled Trials up to September 2008. We also hand-searched relevant journals and article reference lists. We included randomized controlled trials and controlled clinical trials that had objective data for BMI from before and after the intervention, that involved school-based physical activity interventions and that lasted for a minimum of 6 months.
Of 398 potentially relevant articles that we identified, 18 studies involving 18 141 children met the inclusion criteria. The participants were primarily elementary school children. The study duration ranged from 6 months to 3 years. In 15 of these 18 studies, there was some type of co-intervention. Meta-analysis showed that BMI did not improve with physical activity interventions (weighted mean difference -0.05 kg/m(2), 95% confidence interval -0.19 to 0.10). We found no consistent changes in other measures of body composition.
School-based physical activity interventions did not improve BMI, although they had other beneficial health effects. Current population-based policies that mandate increased physical activity in schools are unlikely to have a significant effect on the increasing prevalence of childhood obesity.
•Numerical simulations of moist convection in Jupiter’s atmosphere are performed.•Dependencies on several atmospheric parameters are investigated.•Intermittent emergence of vigorous convective clouds ...is a robust feature.•The period of the intermittency is nearly proportional to deep water abundance.•Mechanism of the intermittency is investigated.
A series of long-term numerical simulations of moist convection in Jupiter’s atmosphere is performed in order to investigate the idealized characteristics of the vertical structure of multi-composition clouds and the convective motions associated with them, varying the deep abundances of condensable gases and the autoconversion time scale, the latter being one of the most questionable parameters in cloud microphysical parameterization. The simulations are conducted using a two-dimensional cloud resolving model that explicitly represents the convective motion and microphysics of the three cloud components, H2O, NH3, and NH4SH imposing a body cooling that substitutes the net radiative cooling. The results are qualitatively similar to those reported in Sugiyama et al. (Sugiyama, K. et al. 2011. Intermittent cumulonimbus activity breaking the three-layer cloud structure of Jupiter. Geophys. Res. Lett. 38, L13201. doi:10.1029/2011GL047878): stable layers associated with condensation and chemical reaction act as effective dynamical and compositional boundaries, intense cumulonimbus clouds develop with distinct temporal intermittency, and the active transport associated with these clouds results in the establishment of mean vertical profiles of condensates and condensable gases that are distinctly different from the hitherto accepted three-layered structure (e.g., Atreya, S.K., Romani, P.N. 1985. Photochemistry and clouds of Jupiter, Saturn and Uranus. In: Recent Advances in Planetary Meteorology. Cambridge Univ. Press, London, pp. 17–68). Our results also demonstrate that the period of intermittent cloud activity is roughly proportional to the deep abundance of H2O gas. The autoconversion time scale does not strongly affect the results, except for the vertical profiles of the condensates. Changing the autoconversion time scale by a factor of 100 changes the intermittency period by a factor of less than two, although it causes a dramatic increase in the amount of condensates in the upper troposphere.
The moist convection layer becomes potentially unstable with respect to an air parcel rising from below the H2O lifting condensation level (LCL) well before the development of cumulonimbus clouds. The instability accumulates until an appropriate trigger is provided by the H2O condensate that falls down through the H2O LCL; the H2O condensate drives a downward flow below the H2O LCL as a result of the latent cooling associated with the re-evaporation of the condensate, and the returning updrafts carry moist air from below to the moist convection layer. Active cloud development is terminated when the instability is completely exhausted. The period of intermittency is roughly equal to the time obtained by dividing the mean temperature increase, which is caused by active cumulonimbus development, by the body cooling rate.
•Atmospheric circulation of a synchronously rotating aquaplanet is examined by a GCM.•Its dependence on the planetary rotation rate is focused.•Four types of circulation structures are ...identified.•Net day-night energy transport is almost insensitive to the circulation structure.•The insensitivity originates from the radiation limit of the moist atmosphere.
In order to investigate a possible variety of atmospheric states realized on a synchronously rotating aquaplanet, an experiment studying the impact of planetary rotation rate is performed using an atmospheric general circulation model (GCM) with simplified hydrological and radiative processes. The entire planetary surface is covered with a swamp ocean. The value of planetary rotation rate is varied from zero to the Earth’s, while other parameters such as planetary radius, mean molecular weight and total mass of atmospheric dry components, and solar constant are set to the present Earth’s values. The integration results show that the atmosphere reaches statistically equilibrium states for all runs; none of the calculated cases exemplifies the runaway greenhouse state. The circulation patterns obtained are classified into four types: Type-I characterized by the dominance of a day-night thermally direct circulation, Type-II characterized by a zonal wave number one resonant Rossby wave over a meridionally broad westerly jet on the equator, Type-III characterized by a long time scale north-south asymmetric variation, and Type-IV characterized by a pair of mid-latitude westerly jets. With the increase of planetary rotation rate, the circulation evolves from Type-I to Type-II and then to Type-III gradually and smoothly, whereas the change from Type-III to Type-IV is abrupt and discontinuous. Over a finite range of planetary rotation rate, both Types-III and -IV emerge as statistically steady states, constituting multiple equilibria. In spite of the substantial changes in circulation, the net energy transport from the day side to the night side remains almost insensitive to planetary rotation rate, although the partition into dry static energy and latent heat energy transports changes. The reason for this notable insensitivity is that the outgoing longwave radiation over the broad area of the day side is constrained by the radiation limit of a moist atmosphere, so that the transport to the night side, which is determined as the difference between the incoming solar radiation and the radiation limit, cannot change greatly.
Some studies have suggested a link between antihypertensive medication and cancer, but the evidence is so far inconclusive. Thus, we aimed to investigate this association in a large individual ...patient data meta-analysis of randomised clinical trials.
We searched PubMed, MEDLINE, The Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov from Jan 1, 1966, to Sept 1, 2019, to identify potentially eligible randomised controlled trials. Eligible studies were randomised controlled trials comparing one blood pressure lowering drug class with a placebo, inactive control, or other blood pressure lowering drug. We also required that trials had at least 1000 participant years of follow-up in each treatment group. Trials without cancer event information were excluded. We requested individual participant data from the authors of eligible trials. We pooled individual participant-level data from eligible trials and assessed the effects of angiotensin-converting enzyme inhibitors (ACEIs), angiotensin II receptor blockers (ARBs), β blockers, calcium channel blockers, and thiazide diuretics on cancer risk in one-stage individual participant data and network meta-analyses. Cause-specific fixed-effects Cox regression models, stratified by trial, were used to calculate hazard ratios (HRs). The primary outcome was any cancer event, defined as the first occurrence of any cancer diagnosed after randomisation. This study is registered with PROSPERO (CRD42018099283).
33 trials met the inclusion criteria, and included 260 447 participants with 15 012 cancer events. Median follow-up of included participants was 4·2 years (IQR 3·0–5·0). In the individual participant data meta-analysis comparing each drug class with all other comparators, no associations were identified between any antihypertensive drug class and risk of any cancer (HR 0·99 95% CI 0·95–1·04 for ACEIs; 0·96 0·92–1·01 for ARBs; 0·98 0·89–1·07 for β blockers; 1·01 0·95–1·07 for thiazides), with the exception of calcium channel blockers (1·06 1·01–1·11). In the network meta-analysis comparing drug classes against placebo, we found no excess cancer risk with any drug class (HR 1·00 95% CI 0·93–1·09 for ACEIs; 0·99 0·92–1·06 for ARBs; 0·99 0·89–1·11 for β blockers; 1·04 0·96–1·13 for calcium channel blockers; 1·00 0·90–1·10 for thiazides).
We found no consistent evidence that antihypertensive medication use had any effect on cancer risk. Although such findings are reassuring, evidence for some comparisons was insufficient to entirely rule out excess risk, in particular for calcium channel blockers.
British Heart Foundation, National Institute for Health Research, Oxford Martin School.
Since 2007, the Telescope Array (TA) experiment, based in Utah, USA, has been observing ultra high energy cosmic rays to understand their origins. The experiment includes a surface detector (SD) ...array and three fluorescence detector (FD) stations. The FD stations, installed surrounding the SD array, measure the air fluorescence light emitted from extensive air showers (EASs) for precise determination of their energies and species. The detectors employed at one of the three FD stations were relocated from the High Resolution Fly's Eye (HiRes) experiment. At the other two stations, newly designed detectors were constructed for the TA experiment. An FD consists of a primary mirror and a camera equipped with photomultiplier tube pixels. To obtain the EAS parameters with high accuracy, understanding the FD optical characteristics is important. In this paper, we report the characteristics and installation of the new FDs and the performances of the FD components. The results of the monitored mirror reflectance during the observation time are also described in this report.
Since its discovery in 2008, the Andromeda galaxy nova M31N 2008-12a has been observed in eruption every single year. This unprecedented frequency indicates an extreme object, with a massive white ...dwarf and a high accretion rate, which is the most promising candidate for the single-degenerate progenitor of a Type Ia supernova known to date. The previous three eruptions of M31N 2008-12a have displayed remarkably homogeneous multiwavelength properties: (i) from a faint peak, the optical light curve declined rapidly by two magnitudes in less than two days, (ii) early spectra showed initial high velocities that slowed down significantly within days and displayed clear He/N lines throughout, and (iii) the supersoft X-ray source (SSS) phase of the nova began extremely early, six days after eruption, and only lasted for about two weeks. In contrast, the peculiar 2016 eruption was clearly different. Here we report (i) the considerable delay in the 2016 eruption date, (ii) the significantly shorter SSS phase, and (iii) the brighter optical peak magnitude (with a hitherto unobserved cusp shape). Early theoretical models suggest that these three different effects can be consistently understood as caused by a lower quiescence mass accretion rate. The corresponding higher ignition mass caused a brighter peak in the free-free emission model. The less massive accretion disk experienced greater disruption, consequently delaying the re-establishment of effective accretion. Without the early refueling, the SSS phase was shortened. Observing the next few eruptions will determine whether the properties of the 2016 outburst make it a genuine outlier in the evolution of M31N 2008-12a.
UX Orionis stars (UXors) are Herbig Ae/Be or T Tauri stars exhibiting sporadic occultation of stellar light by circumstellar dust. GM Cephei is such a UXor in the young (∼4 Myr) open cluster Trumpler ...37, showing prominent infrared excess, emission-line spectra, and flare activity. Our photometric monitoring (2008-2018) detects (1) an ∼3.43 day period, likely arising from rotational modulation by surface starspots, (2) sporadic brightening on timescales of days due to accretion, (3) irregular minor flux drops due to circumstellar dust extinction, and (4) major flux drops, each lasting for a couple of months with a recurrence time, though not exactly periodic, of about two years. The star experiences normal reddening by large grains, i.e., redder when dimmer, but exhibits an unusual "blueing" phenomenon in that the star turns blue near brightness minima. The maximum extinction during relatively short (lasting ≤50 days) events, is proportional to the duration, a consequence of varying clump sizes. For longer events, the extinction is independent of duration, suggestive of a transverse string distribution of clumps. Polarization monitoring indicates an optical polarization varying ∼3%-8%, with the level anticorrelated with the slow brightness change. Temporal variation of the unpolarized and polarized light sets constraints on the size and orbital distance of the circumstellar clumps in the interplay with the young star and scattering envelope. These transiting clumps are edge-on manifestations of the ring- or spiral-like structures found recently in young stars with imaging in infrared of scattered light, or in submillimeter of thermalized dust emission.
Controversy exists as to whether the threshold for blood pressure-lowering treatment should differ between people with and without type 2 diabetes. We aimed to investigate the effects of blood ...pressure-lowering treatment on the risk of major cardiovascular events by type 2 diabetes status, as well as by baseline levels of systolic blood pressure.
We conducted a one-stage individual participant-level data meta-analysis of major randomised controlled trials using the Blood Pressure Lowering Treatment Trialists' Collaboration dataset. Trials with information on type 2 diabetes status at baseline were eligible if they compared blood pressure-lowering medications versus placebo or other classes of blood pressure-lowering medications, or an intensive versus a standard blood pressure-lowering strategy, and reported at least 1000 persons-years of follow-up in each group. Trials exclusively on participants with heart failure or with short-term therapies and acute myocardial infarction or other acute settings were excluded. We expressed treatment effect per 5 mm Hg reduction in systolic blood pressure on the risk of developing a major cardiovascular event as the primary outcome, defined as the first occurrence of fatal or non-fatal stroke or cerebrovascular disease, fatal or non-fatal ischaemic heart disease, or heart failure causing death or requiring hospitalisation. Cox proportional hazard models, stratified by trial, were used to estimate hazard ratios (HRs) separately by type 2 diabetes status at baseline, with further stratification by baseline categories of systolic blood pressure (in 10 mm Hg increments from <120 mm Hg to ≥170 mm Hg). To estimate absolute risk reductions, we used a Poisson regression model over the follow-up duration. The effect of each of the five major blood pressure-lowering drug classes, including angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, β blockers, calcium channel blockers, and thiazide diuretics, was estimated using a network meta-analysis framework. This study is registered with PROSPERO, CRD42018099283.
We included data from 51 randomised clinical trials published between 1981 and 2014 involving 358 533 participants (58% men), among whom 103 325 (29%) had known type 2 diabetes at baseline. The baseline mean systolic/diastolic blood pressure of those with and without type 2 diabetes was 149/84 mm Hg (SD 19/11) and 153/88 mm Hg (SD 21/12), respectively. Over 4·2 years median follow-up (IQR 3·0–5·0), a 5 mm Hg reduction in systolic blood pressure decreased the risk of major cardiovascular events in both groups, but with a weaker relative treatment effect in participants with type 2 diabetes (HR 0·94 95% CI 0·91–0·98) compared with those without type 2 diabetes (0·89 0·87–0·92; pinteraction=0·0013). However, absolute risk reductions did not differ substantially between people with and without type 2 diabetes because of the higher absolute cardiovascular risk among participants with type 2 diabetes. We found no reliable evidence for heterogeneity of treatment effects by baseline systolic blood pressure in either group. In keeping with the primary findings, analysis using stratified network meta-analysis showed no evidence that relative treatment effects differed substantially between participants with type 2 diabetes and those without for any of the drug classes investigated.
Although the relative beneficial effects of blood pressure reduction on major cardiovascular events were weaker in participants with type 2 diabetes than in those without, absolute effects were similar. The difference in relative risk reduction was not related to the baseline blood pressure or allocation to different drug classes. Therefore, the adoption of differential blood pressure thresholds, intensities of blood pressure lowering, or drug classes used in people with and without type 2 diabetes is not warranted.
British Heart Foundation, UK National Institute for Health Research, and Oxford Martin School.
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