Publications

Abstract : Predictions of large amplitude roll motions and capsize events have proven to be difficult and include large uncertainty. A factor that contributes to the difficulty in predictions is a lack of knowledge of resultant forces and moments for large roll angles. The equations currently used by numerical models to predict forces and moments due to roll motion are based on experimental data performed within a small range of roll amplitudes. For this reason, a data set of forces and moments is needed to verify that the model predictions are accurate in the U per ranges. If the predictions are inaccurate for the larger roll angles, a need may exist to develop new modes to predict the forces and moments for these larger roll amplitudes. In 2006, NSWCCD performed an experiment on Model 5613 to obtain the model scale constrained seakeeping results during large amplitude motions in waves, in contrast to the calm water experiments of 2005. Similar to the 2005 experiment, the effects of model speed, roll amplitude roll frequency, wave height and wave len on the forces and moments were investigated in an effort to develop a database of surge, sway, and heave forces, and roll, itch and yaw moments as a result of flare amplitude forced roll motions in waves. This report will describe the experimental setup and results of the 2006 experiment.

This report is a study of the kinetics of contact charging resulting from the rolling of millimeter-sized metallic spheres on flat surfaces of polystyrene (PS). Charging was studied (i) for different values of the relative humidity (RH) of the air in contact with the system, (ii) in acidic and basic atmospheres, and (iii) for a series of PS surfaces oxidized to different degrees. The rates of charging increased with increasing RH; they were higher in basic atmospheres than in neutral or acidic ones and correlated with the numbers of hydrophilic groups on the surface of the polymer. These findings are consistent with a mechanism that implicates a thin film of water on the surface of PS as an important element of tribocharging in this system.

Four years after the EAT-Lancet landmark report, worldwide movements call for action to reorient food systems to healthy diets that respect planetary boundaries. Since dietary habits are inherently local and personal, any shift toward healthy and sustainable diets going against this identity will have an uphill road. Therefore, research should address the tension between the local and global nature of the biophysical (health, environment) and social dimensions (culture, economy). Advancing the food system transformation to healthy, sustainable diets transcends the personal control of engaging consumers. The challenge for science is to scale-up, to become more interdisciplinary, and to engage with policymakers and food system actors. This will provide the evidential basis to shift from the current narrative of price, convenience, and taste to one of health, sustainability, and equity. The breaches of planetary boundaries and the environmental and health costs of the food system can no longer be considered externalities. However, conflicting interests and traditions frustrate effective changes in the human-made food system. Public and private stakeholders must embrace social inclusiveness and include the role and accountability of all food system actors from the microlevel to the macrolevel. To achieve this food transformation, a new “social contract,” led by governments, is needed to redefine the economic and regulatory power balance between consumers and (inter)national food system actors.

Significance Soft structures and materials are easily susceptible to mechanical instabilities, which can be harnessed for function, such as controlled locomotion. Here, we show how a reversible conical buckling instability of a pneumatically actuated sheet leads to an amphibious morph-bot that can crawl on land or swim in water. Our approach enables the design of novel shape-changing robots and other bioinspired machines at multiple scales using simple constituent materials and power sources.

Abstract Background Greater maternal adiposity before or during pregnancy is associated with greater offspring adiposity throughout childhood, but the extent to which this is due to causal intrauterine or periconceptional mechanisms remains unclear. Here we use Mendelian Randomization (MR) with polygenic risk scores (PRS) to investigate whether associations between maternal pre-/early pregnancy body mass index (BMI) and offspring adiposity from birth to adolescence are causal. Methods We undertook confounder adjusted multivariable (MV) regression and MR using mother-offspring pairs from two UK cohorts: Avon Longitudinal Study of Parents and Children (ALSPAC) and Born in Bradford (BiB). In ALSPAC and BiB the outcomes were birthweight (BW; N = 9339) and BMI at age 1 and 4 years ( N = 8659 to 7575). In ALSPAC only we investigated BMI at 10 and 15 years ( N = 4476 to 4112) and dual-energy X-ray absorptiometry (DXA) determined fat mass index (FMI) from age 10–18 years ( N = 2659 to 3855). We compared MR results from several PRS, calculated from maternal non-transmitted alleles at between 29 and 80,939 single nucleotide polymorphisms (SNPs). Results MV and MR consistently showed a positive association between maternal BMI and BW, supporting a moderate causal effect. For adiposity at most older ages, although MV estimates indicated a strong positive association, MR estimates did not support a causal effect. For the PRS with few SNPs, MR estimates were statistically consistent with the null, but had wide confidence intervals so were often also statistically consistent with the MV estimates. In contrast, the largest PRS yielded MR estimates with narrower confidence intervals, providing strong evidence that the true causal effect on adolescent adiposity is smaller than the MV estimates ( P difference = 0.001 for 15 year BMI). This suggests that the MV estimates are affected by residual confounding, therefore do not provide an accurate indication of the causal effect size. Conclusions Our results suggest that higher maternal pre-/early-pregnancy BMI is not a key driver of higher adiposity in the next generation. Thus, they support interventions that target the whole population for reducing overweight and obesity, rather than a specific focus on women of reproductive age.

Background: Type 2 Diabetes Mellitus (T2DM) affects 10.5% of the US population (~34.2 million people). While previous studies have shown that high intake of sodium is associated with the worsening of the T2DM parameters, it is unclear whether dietary sodium intake is associated with incidence of T2DM. We prospectively examined the association of sodium and potassium intake and risk for T2DM among participants of the Million Veteran Program (MVP). Methods: Between 2011 to 2020, 379,852 participants from the MVP completed a semi-quantitative food frequency questionnaire (sFFQ). Incidence of T2DM was ascertained using ICD-9 code 258.xx from electronic health records. We used Cox proportional hazards model to calculate hazard ratio (HR) with 95% confidence intervals (CIs) for T2DM adjusting for confounding factors. Results: Among the 234,721 veterans analyzed, mean age was 65 years (age range 19-106), 91% were male, and 88% were Caucasian. The observed energy-adjusted mean sodium intake was 1222 mg/day (1103 for females, 1234 for males) and potassium intake was 2596 mg/day (2534 for females, 2602 for males). During a mean follow-up of 4.4 years, 8,753 participants developed T2DM. After adjusting for confounding factors, a higher sodium intake was associated with 11% higher risk of T2DM (HR: 1.11, 95% CI: 1.04, 1.19, p-trend=0.0006); while a higher potassium intake was associated with a 6% lower risk of T2DM (HR: 0.94, 95% CI: 0.92, 0.97) (Figure). Conclusion: Higher intake of dietary sodium and lower intake of dietary potassium were each associated with a higher risk of developing T2DM among US veterans.

Background: Smokers in the general population have lower thyrotropin (TSH) and higher free triiodothyronine (fT3) and free thyroxine (fT4) concentrations, but the results in pregnant population vary from no effect to a decrease in TSH and fT4 concentrations and an increase in fT3 levels. Our objective was to further evaluate the question of whether there is an association between smoking, before and during pregnancy, with maternal thyroid function during pregnancy and with the risk for subsequent hypothyroidism. Methods: Our study population was a prospective population-based cohort (N=9362), the Northern Finland Birth Cohort 1986, with extensive data throughout gestation. The mothers underwent serum sampling in early pregnancy. The samples were assayed for TSH, fT3, fT4, thyroid-peroxidase antibodies (TPO-Ab), and thyroglobulin antibodies (TG-Abs) (n=5805). Mothers with thyroid dysfunction diagnosed before or during pregnancy were excluded, leaving 4837 euthyroid mothers. The smoking status of mothers and fathers were requested by questionnaires during pregnancy. Subsequent maternal morbidity relating to hypothyroidism 20 years after the index pregnancy was evaluated using national registers. Results: Euthyroid mothers who smoked before, or continued smoking during first trimester of pregnancy, had higher serum fT3 (p<0.001) and lower fT4 (p=0.023) concentrations than nonsmokers. Smoking in the second trimester was associated with higher fT3 (p<0.001) concentrations, but no difference in fT4 concentrations compared with nonsmokers. TG-Abs were less common among smoking than nonsmoking mothers (2.5% vs. 4.7%, p<0.001), but the prevalence of TPO-Ab was similar. Paternal smoking had no independent effect on maternal early pregnancy thyroid hormone or antibody concentrations. The risk of subsequent maternal hypothyroidism after follow-up of 20 years was similar among prepregnancy smokers and nonsmokers. Conclusions: In euthyroid women, smoking during pregnancy was associated with higher fT3 levels and lower fT4 levels; possibly reflecting smoking-induced changes in peripheral metabolism of thyroid hormones. No differences were found in TSH concentrations between smokers and nonsmokers. Our results differ from those of the general population, which usually have shown smoking-induced thyroidal stimulation. This is possibly due to pregnancy-induced changes in thyroid function. Decreases in fT4 levels among smokers might predispose to hypothyroidism or hypothyroxinemia during pregnancy. Despite these changes in thyroid function, smoking did not increase the woman's risk of subsequent hypothyroidism.

No abstract is provided for this article.

Summary We studied the process of deterioration of a hydrogen maser’s Teflon storage bulb coating, and examined the coating’s physical and chemical characteristics. The deterioration, which accompanied exposure to the maser’s atomic hydrogen beam, was marked by decreasing maser line Q and microwave output power. The likelihood of Teflon degradation by ultraviolet radiation from the beam source was eliminated. Teflon from the bulb, and Teflon from the same original batch, were compared with Teflon from

This paper describes applications in microfabrication using patterned self-assembled monolayers (SAMs) formed by microcontact printing. Microcontact printing is a flexible new technique that forms patterned SAMs with regions terminated by different chemical functionalities (and thus different physical and chemical properties), in patterns with dimensions. Patterns of SAM are formed using an alkanethiol as an `ink', and printing the alkanethiol on a metal support with elastomeric `stamp'. We fabricate the stamp by moulding a silicone elastomer using a master prepared by optical or x-ray microlithography or by other techniques. SAMs of long-chain alkanethiolates on gold and other metals can act as nanometer resists by protecting the supporting metal from corrosion by appropriately formulated etchants: the fabrication of microstructures of gold and silicon demonstrates the utility of patterned SAMs (formed by ) as nm resists. Patterned SAMs formed by can also control the wettability of a surface on the scale. The organization of liquids in patterned arrays with dimensions, and the patterned deposition of microcrystals and microcrystal arrays illustrate the use of controlled wettability for microfabrication.