Tsunami waves extensively resurfaced the shorelines of an early Martian ocean.

It has been proposed that ~3.4 billion years ago an ocean fed by enormous catastrophic floods covered most of the Martian northern lowlands. However, a persistent problem with this hypothesis is the lack of definitive paleoshoreline features. Here, based on geomorphic and thermal image mapping in the circum-Chryse and northwestern Arabia Terra regions of the northern plains, in combination with numerical analyses, we show evidence for two enormous tsunami events possibly triggered by bolide impacts, resulting in craters ~30 km in diameter and occurring perhaps a few million years apart. The tsunamis produced widespread littoral landforms, including run-up water-ice-rich and bouldery lobes, which extended tens to hundreds of kilometers over gently sloping plains and boundary cratered highlands, as well as backwash channels where wave retreat occurred on highland-boundary surfaces. The ice-rich lobes formed in association with the younger tsunami, showing that their emplacement took place following a transition into a colder global climatic regime that occurred after the older tsunami event. We conclude that, on early Mars, tsunamis played a major role in generating and resurfacing coastal terrains.

Associations of serum ß-carotene and retinol concentrations with insulin resistance: the Toon Health Study.

OBJECTIVE: Although green and yellow vegetables have beneficial effects against type 2 diabetes, the relationship of their nutritive content with insulin resistance is poorly understood. The aim of this study was to examine the associations of serum ß-carotene and retinol concentrations with glucose and insulin concentrations. METHODS: We recruited 951 Japanese men and women ages 30 to 79 y who were not undergoing treatment for diabetes and measured their serum ß-carotene and retinol concentrations. A 75-g oral glucose tolerance test was performed and the homeostasis model assessment for insulin resistance (HOMA-IR) and the Matsuda Index were calculated as measures of insulin resistance. Several confounding factors were adjusted for with multivariable logistic models. RESULTS: Multivariable-adjusted odds ratios of the highest quartile of serum ß-carotene compared with the lowest quartile for HOMA-IR >1.6 and Matsuda Index <4.9 were 0.56 (95% confidence interval, 0.34-0.94) and 0.62 (0.37-1.02), respectively. When stratified by sex and overweight status, these associations were observed for women and non-overweight individuals. Serum retinol concentration was not associated with either index. Furthermore, according to the nutritional survey, serum ß-carotene concentration was associated with green and yellow vegetable intake (P = 0.01). CONCLUSION: Our findings suggest that higher serum ß-carotene levels, associated with higher intake of green and yellow vegetables, confer beneficial effects against insulin resistance.

The impact of masticatory ability as evaluated by salivary flow rates on obesity in Japanese: The Toon health study.

OBJECTIVE: This study examined the associations of masticatory ability evaluated by chewing-gum-stimulated salivary flow rate with anthropometric indices among a general Japanese population. METHODS: In total, 921 Japanese men and women aged 30-79 years participated in this cross-sectional study. Saliva production was stimulated by 5 min of gum chewing, then collected; salivary flow rate was calculated as g/min. Overweight, abdominal obesity in terms of waist circumference (WC), and waist-hip ratio (WHR), and elevated skinfold thickness statuses were determined. RESULTS: The multivariable odds ratio and 95% confidence intervals of overweight, abdominal obesity (WC, WHR), and elevated skinfold thickness status for highest vs. lowest quartile of salivary flow rate were 0.59 (0.37-0.95, P for trend = 0.02), 0.65 (0.43-0.98, P = 0.03), 0.54 (0.35-0.83, P < 0.01), and 0.61 (0.39-0.96, P < 0.01), respectively. The linear trends of multivariable-adjusted means of BMI, WC, WHR, and skinfold thickness according to quartiles of salivary flow rate did not vary after stratification by overweight status. CONCLUSIONS: Higher stimulated salivary flow rate, a surrogate marker for mastication ability, was associated with lower prevalence of overweight, abdominal obesity (whether WC- or WHR-defined), and elevated skinfold thickness among the general Japanese population.