A short note on the BMI and on secular changes in BMI

Human size changes over time with worldwide secular trends in height, weight, and body mass index (BMI). There is general agreement to relate the state of nutrition to height and weight, and to ratios of weight-to-height. The BMI is a ratio. It is commonly used to classify underweight, overweight and obesity in adults. Yet, the BMI is inappropriate to provide any immediate information on body composition. It is accepted that the BMI is “a simple index to classify underweight, overweight and obesity in adults”. It is stated that “policies, programmes and investments need to be “nutrition-sensitive”, which means they must have positive impacts on nutrition”. It is also stated that “a need for policies that address all forms of malnutrition by making healthy foods accessible and affordable, while restricting unhealthy foods through fiscal and regulatory restrictions“. But these statements are neither warranted by arithmetic considerations, nor by historic evidence. Measuring the BMI is an appropriate screening tool for detecting an unusual weight-to-height ratio, but the BMI is an inappropriate tool for estimating body composition, or suggesting medical and health policy decisions.

Changes in Tornado Climatology Accompanying the Enhanced Fujita Scale

United States tornado records form the basis for a variety of meteorological, climatological and disaster-risk analyses, but how reliable are they in light of changing standards for rating, as with the 2007 transition of Fujita (F) to Enhanced Fujita (EF) damage scales? To what extent are recorded tornado metrics subject to such influences that may be nonmeteorological in nature? While addressing these questions with utmost thoroughness is too large of a task for any one study, and may not be possible given the many variables and uncertainties involved, some variables that are recorded in large samples are ripe for new examination. We assess basic tornado-path characteristics—damage rating, length, width, and occurrence time, as well as some combined and derived measures—for a 24-yr period of constant path-width recording standard that also coincides with National Weather Service modernization and the WSR-88D deployment era. The middle of that period (in both time and approximate tornado counts) crosses the official switch from F to EF. At least minor shifts in all assessed path variables are associated directly with that change, contrary to the intent of EF implementation. Major and essentially stepwise expansion of tornadic path widths occurred immediately upon EF usage, and widths have expanded still further within the EF era. We also document lesser increases in path lengths, and in tornadoes rated at least EF1 compared to EF0. These apparently secular changes in the tornado data can impact research dependent on bulk tornado-path characteristics and damage-assessment results.

Secular changes in human reproduction and assisted reproductive technologies

Since the middle to late 20th century the majority of children born in the developing world have been likely to enter into post-reproductive age. Currently, child mortality is at its lowest level in human history. While more children are living to post reproductive age, approximately 15% of couples are experiencing infecundity. This is either a result of one or both members of the couple being infecund, or, despite both being fecund, the interaction between them prevents fertility for some reason. Assisted reproductive technologies have provided many infertile couples an opportunity to have children. Assisted reproductive technologies operate by intervening and manipulating gametic and intrauterine natural selection. This paper discusses the possible influence of assisted reproductive technologies on child development. This paper outlines some of the reported changes in children resulting from assisted reproductive technologies. Although, few people are either aware or care about possible long term consequences of relaxed natural selection contributed by medical intervention (i.e. assisted reproductive technologies) we have little understanding to what extent such medical interference may affect long term fitness in humans.

Perturbations of the orbital elements due to the magnetic-like part of the field of a plane gravitational wave

In this paper, we focus on the secular changes of the orbital elements of a planet in the solar system, determined by the magnetic-like part of a gravitational wave field. Using Fermi coordinates, we show that the total force acting on a test particle is made of two contributions: a gravito-electric one and a gravito-magnetic one. While the electric-like force has been thoroughly discussed in the past, the effect of the gravito-magnetic force, which depends on the velocity of the test particle, has not been considered yet. We obtain approximated results to some orders in the orbital eccentricity and show that these effects are much smaller than the corresponding gravito-electric ones.

Revisiting stepwise ocean oxygenation with authigenic barium enrichments in marine mudrocks

There are current debates around the extent of global ocean oxygenation, particularly from the late Neoproterozoic to the early Paleozoic, based on analyses of various geochemical indices. We present a temporal trend in excess barium (Baexcess) contents in marine organic-rich mudrocks (ORMs) to provide an independent constraint on global ocean redox evolution. The absence of remarkable Baexcess enrichments in Precambrian (>ca. 541 Ma) ORMs suggests limited authigenic Ba formation in oxygen- and sulfate-deficient oceans. By contrast, in the Paleozoic, particularly the early Cambrian, ORMs are marked by significant Baexcess enrichments, corresponding to substantial increases in the marine sulfate reservoir and oxygenation level. Analogous to modern sediments, the Mesozoic and Cenozoic ORMs exhibit no prominent Baexcess enrichments. We suggest that variations in Baexcess concentrations of ORMs through time are linked to secular changes in the marine dissolved Ba reservoir associated with elevated marine sulfate levels and global ocean oxygenation. Further, unlike Mo, U, and Re abundances, significant Baexcess enrichments in ORMs indicate that the overall ocean oxygenation level in the early Paleozoic was substantially lower than at present.

Searching on campus? The marriage market effects of changing student sex ratios

This paper studies how secular changes in the student sex ratio affect marriage market outcomes for university graduates. Using data from Germany, I find that a higher own-gender share within the field of study reduces marriage market opportunities for women, while the opposite is true for men. Moreover, an imbalanced student sex ratio changes the composition of couples. For women, a higher female share decreases the probability of having a spouse from the same field, while men are more likely to marry down with respect to educational status when the male share is high. These findings suggest that the secular changes in the sex ratio of university students have important implications beyond the labor market by affecting the household composition among the high-skilled population.

Secular Change in Body Size and Somatotype of Indonesian Children aged 7–15 Years (1999–2019)

BACKGROUND: Secular changes assessment can help identifying the quality of health, wealth, and nutrition among populations and provide suggestions for policymakers. AIM: To examine the secular changes in weight, height, body mass index, and somatotype in Indonesian children between 1999 and 2019. METHODS: This cross-sectional study was conducted in 1999 and 2019 on 2021 children aged 7–15 years in Yogyakarta, Indonesia. Anthropometric measurements including height, weight, humerus and femur breadths, circumferences of upper arm and calf; skinfold thickness of triceps, subscapular, suprailiac, and calf were measured. Body mass index (BMI) was calculated as kg/m2. Somatotype components were defined by the Carter-Heath method. Statistical analyses used were three-ways ANOVA and least significant difference post hoc tests. RESULTS: Significant differences for boys and girls were found for height, weight, BMI, and three components of somatotype across the 2-time points. The boys in period 2019 were the tallest and girls were the heaviest, and for BMI, the highest value was observed in 2019 (girls). The children in the 1999 period had somatotype values 3.3 - 3.3 - 3.7 (boys) and 3.9 - 3.0 - 3.5 (girls), while in the 2019 period the somatotype values for boys were 3.5 - 4.5 - 3.0 and 4.3 - 4.1 - 2.4 for girls. CONCLUSION: In general, based on the order of age, there is a similar pattern between children in the two periods. Among Indonesian children from 1999 to 2019, there were positive trends in weight, BMI, endomorph, and mesomorph components, whereas a negative trend for the ectomorph component.

Secular Changes in Mean Height of Children in Japan and South Korea-Suspension in Height Increases and BMI

Japan and South Korea achieved marvelous economic progress after WWII. Food consumption increased in quantity and quality, with animal-sourced products conspicuously augmented. Children grew in height unprecedentedly. Japanese children, however, ceased to grow taller in the 1990s, while supply of animal protein was still increasing. Korean children kept growing taller to overtake their Japanese peers by 3 cm in the mid-2000s, but they also stopped to grow any taller afterwards, while animal products kept increasing vigorously toward the end of the 2010s. Children in Japan started to turn away from fruit in the mid-1970s, to eat in the 2000s less than 10% of fruit by the older generations. Children in Korea started to steer away from vegetables in the early 1990s, to eat less than 10% of vegetables eaten by the older generations in their 50s-60s in the mid-2010s. Consuming sufficient animal-sourced products with very little vegetables/fruit, children, particularly in South Korea have been increasing in BMS in the past two decades, with a sign of declining height. Keywords: Animal Protein; BMS; Japan; Teens; South Korea; Vegetables/Fruit

Continental basalts track secular cooling of the mantle and the onset of modern plate tectonics

The temperature of the convecting mantle exerts a first-order control on the tectonic behaviour of Earth’s lithosphere. Although the mantle has likely been cooling since the Archaean eon (4.0–2.5 billion years ago), how mantle temperature evolved thereafter is poorly understood. Here, we apply a statistical analysis to secular changes in the alkali index (A.I. = whole-rock (Na2O + K2O)2/(SiO2 – 38) as weight%) of intracontinental basalts globally to constrain the evolution of mantle potential temperature (Tp) over the past billion years. During the early Neoproterozoic, Tp remained relatively constant at ~1450 °C until the Cryogenian (720 to 635 million years ago), when mantle temperature dropped by ~50 °C over <180 million years. This remarkable episode of cooling records the onset of modern-style plate tectonics, which has been suggested to have been triggered by a dramatic increase in the supply of sediments to lubricate trenches during the thawing of the Snowball Earth.