An improved algorithm to harmonize child overweight and obesity prevalence rates

BACKGROUND: Prevalence rates of child overweight and obesity for a group of children vary depending on the BMI reference and cut-off used. Previously we developed an algorithm to convert prevalence rates based on one reference to those based on another. OBJECTIVE: To improve the algorithm by combining information on overweight and obesity prevalence. METHODS: The original algorithm assumed that prevalence according to two different cut-offs A and B differed by a constant amount dz $$dz$$ on the z-score scale. However the results showed that the z-score difference tended to be greater in the upper tail of the distribution and was better represented by b × dz $$b\times dz$$ , where b $$b$$ was a constant that varied by group. The improved algorithm uses paired prevalence rates of overweight and obesity to estimate b $$b$$ for each group. Prevalence based on cut-off A is then transformed to a z-score, adjusted up or down according to b × dz $$b\times dz$$ and back-transformed, and this predicts prevalence based on cut-off B. The algorithm's performance was tested on 228 groups of children aged 6-17 years from 20 countries. RESULTS: The revised algorithm performed much better than the original. The standard deviation (SD) of residuals, the difference between observed and predicted prevalence, was 0.8% (n = 2320 comparisons), while the SD of the difference between pairs of the original prevalence rates was 4.3%, meaning that the algorithm explained 96.7% of the baseline variance (88.2% with original algorithm). CONCLUSIONS: The improved algorithm appears to be effective at harmonizing prevalence rates of child overweight and obesity based on different references

Exploring an algorithm to harmonize International Obesity Task Force and World Health Organization child overweight and obesity prevalence rates

BACKGROUND: The International Obesity Task Force (IOTF) and World Health Organization (WHO) body mass index (BMI) cut-offs are widely used to assess child overweight, obesity and thinness prevalence, but the two references applied to the same children lead to different prevalence rates. OBJECTIVES: To develop an algorithm to harmonize prevalence rates based on the IOTF and WHO cut-offs, to make them comparable. METHODS: The cut-offs are defined as age-sex-specific BMI z-scores, for example, WHO +1 SD for overweight. To convert an age-sex-specific prevalence rate based on reference cut-off A to the corresponding prevalence based on reference cut-off B, first back-transform the z-score cut-offs z A and z B to age-sex-specific BMI cut-offs, then transform the BMIs to z-scores z B , A and z A , B using the opposite reference. These z-scores together define the distance between the two cut-offs as the z-score difference dz A , B = 1 2 z B - z A + z A , B - z B , A . Prevalence in the target group based on cut-off A is then transformed to a z-score, adjusted up or down according to dz A , B and back-transformed, and this predicts prevalence based on cut-off B. The algorithm's performance was tested on 74 groups of children from 14 European countries. RESULTS: The algorithm performed well. The standard deviation (SD) of the difference between pairs of prevalence rates was 6.6% (n = 604), while the residual SD, the difference between observed and predicted prevalence, was 2.3%, meaning that the algorithm explained 88% of the baseline variance. CONCLUSIONS: The algorithm goes some way to addressing the problem of harmonizing overweight and obesity prevalence rates for children aged 2-18

CATASTROPHIC FLANK COLLAPSE ON TA’U ISLAND AND SUBSEQUENT TSUNAMI: HAS THIS OCCURRED DURING THE LAST 170 YEARS?

Ta’u, the easternmost inhabited island in the Samoan Islands archipelago, exhibits a series of down-faulted benches on its southern flank, believed to be the remnant of ~30 km3 catastrophic collapse. A historical map of Ta’u charted in 1839 during the United States Exploring Expedition, which did not show the benches, suggests that the event occurred less than 170 years ago. A collapse event of this magnitude would have generated a locally devastating tsunami, with possible impacts experienced at the regional level. However, no written or oral records of such an event exist. A number of key questions thus emerge, and formed the basis for this study. Did this event actually happen within the last 170 years, and if so, how and why could it have gone unnoticed? Or, is the event much older than the impression obtained from the literature? The catastrophic flank collapse was modeled using 100 m contour-resolution bathymetry data of the Ta’u region, coupled with rational assumptions made on the geometry of the failed mass. This enabled numerical landslide- tsunami simulation in the Cornell Multigrid Coupled Tsunami Model (COMCOT). The results indicate that if an event of this magnitude occurred in the last 170 years, it could not have gone unnoticed by local inhabitants. It thus seems likely that the initial survey conducted during the Exploring Expedition was inaccurate. Nevertheless, the well-preserved nature of the benches indicates collapse relatively recently and raises the possibility of future collapse

Nano-scale reservoir computing

This work describes preliminary steps towards nano-scale reservoir computing using quantum dots. Our research has focused on the development of an accumulator-based sensing system that reacts to changes in the environment, as well as the development of a software simulation. The investigated systems generate nonlinear responses to inputs that make them suitable for a physical implementation of a neural network. This development will enable miniaturisation of the neurons to the molecular level, leading to a range of applications including monitoring of changes in materials or structures. The system is based around the optical properties of quantum dots. The paper will report on experimental work on systems using Cadmium Selenide (CdSe) quantum dots and on the various methods to render the systems sensitive to pH, redox potential or specific ion concentration. Once the quantum dot-based systems are rendered sensitive to these triggers they can provide a distributed array that can monitor and transmit information on changes within the material.Comment: 8 pages, 9 figures, accepted for publication in Nano Communication Networks, http://www.journals.elsevier.com/nano-communication-networks/. An earlier version was presented at the 3rd IEEE International Workshop on Molecular and Nanoscale Communications (IEEE MoNaCom 2013

Promotion of faster weight gain in infants born small for gestational age - Is there an adverse effect on later blood pressure?

Background - Being born small for gestational age is associated with later risk factors for cardiovascular disease, such as high blood pressure. Promotion of postnatal growth has been proposed to ameliorate these effects. There is evidence in animals and infants born prematurely, however, that promotion of growth by increased postnatal nutrition increases rather than decreases later cardiovascular risk. We report the long-term impact of growth promotion in term infants born small for gestational age ( birth weight < 10th percentile).Methods and Results - Blood pressure was measured at 6 to 8 years in 153 of 299 ( 51%) of a cohort of children born small for gestational age and randomly assigned at birth to receive either a standard or a nutrient-enriched formula. The enriched formula contained 28% more protein than standard formula and promoted weight gain. Diastolic and mean ( but not systolic) blood pressure was significantly lower in children assigned to standard compared with nutrient-enriched formula ( unadjusted mean difference for diastolic blood pressure, - 3.2 mm Hg; 95% CI, - 5.8 to - 0.5; P = 0.02) independent of potential confounding factors ( adjusted difference, - 3.5 mm Hg; P = 0.01). In observational analyses, faster weight gain in infancy was associated with higher later blood pressure.Conclusions - In the present randomized study targeted to investigate the effect of early nutrition on long-term cardiovascular health, we found that a nutrient-enriched diet increased later blood pressure. These findings support an adverse effect of relative "overnutrition" in infancy on long-term cardiovascular disease risk, have implications for the early origins of cardiovascular disease hypothesis, and do not support the promotion of faster weight gain in infants born small for gestational age