3D X-Ray Imaging of Continuous Objects beyond the Depth of Focus Limit.

X-ray ptychography is becoming the standard method for sub-30 nm imaging of thick extended samples. Available algorithms and computing power have traditionally restricted sample reconstruction to 2D slices. We build on recent progress in optimization algorithms and high performance computing to solve the ptychographic phase retrieval problem directly in 3D. Our approach addresses samples that do not fit entirely within the depth of focus of the imaging system. Such samples pose additional challenges because of internal diffraction effects within the sample. We demonstrate our approach on a computational sample modeled with 17 million complex variables.

Uncertainty quantification for nuclear density functional theory and information content of new measurements.

Statistical tools of uncertainty quantification can be used to assess the information content of measured observables with respect to present-day theoretical models, to estimate model errors and thereby improve predictive capability, to extrapolate beyond the regions reached by experiment, and to provide meaningful input to applications and planned measurements. To showcase new opportunities offered by such tools, we make a rigorous analysis of theoretical statistical uncertainties in nuclear density functional theory using Bayesian inference methods. By considering the recent mass measurements from the Canadian Penning Trap at Argonne National Laboratory, we demonstrate how the Bayesian analysis and a direct least-squares optimization, combined with high-performance computing, can be used to assess the information content of the new data with respect to a model based on the Skyrme energy density functional approach. Employing the posterior probability distribution computed with a Gaussian process emulator, we apply the Bayesian framework to propagate theoretical statistical uncertainties in predictions of nuclear masses, two-neutron dripline, and fission barriers. Overall, we find that the new mass measurements do not impose a constraint that is strong enough to lead to significant changes in the model parameters. The example discussed in this study sets the stage for quantifying and maximizing the impact of new measurements with respect to current modeling and guiding future experimental efforts, thus enhancing the experiment-theory cycle in the scientific method.

Optimized chiral nucleon-nucleon interaction at next-to-next-to-leading order.

We optimize the nucleon-nucleon interaction from chiral effective field theory at next-to-next-to-leading order (NNLO). The resulting new chiral force NNLO(opt) yields χ(2)≈1 per degree of freedom for laboratory energies below approximately 125 MeV. In the A=3, 4 nucleon systems, the contributions of three-nucleon forces are smaller than for previous parametrizations of chiral interactions. We use NNLO(opt) to study properties of key nuclei and neutron matter, and we demonstrate that many aspects of nuclear structure can be understood in terms of this nucleon-nucleon interaction, without explicitly invoking three-nucleon forces.

Differences in coronary mortality can be explained by differences in cholesterol and saturated fat intakes in 40 countries but not in France and Finland. A paradox.

BACKGROUND: For decades, the coronary heart disease (CHD) mortality rate has been four or more times higher in Finland than in France despite comparable intakes of dietary cholesterol and saturated fat. A potential answer to this paradox is provided by this study of 40 countries and the analyses of other nutrients in the diets besides cholesterol and saturated fat. METHODS AND RESULTS: CHD death rates for men aged 55 to 64 years were derived from the World Health Organization annual vital statistics. Dietary intakes were gathered from the Food and Agriculture Organization of the United Nations database. Forty countries at various levels of economic development and 40 dietary variables were investigated, including a lipid score that combined the intakes of cholesterol and saturated fat (Cholesterol-Saturated Fat Index [CSI]). The CSI was significantly and positively related to CHD mortality in the 40 countries. The countries with low CSIs had low CHD death rates. Countries with high CSIs had a wide range of CHD death rates. France, Finland, and other Western industrialized countries had similar CSIs. After adjusting for cholesterol and saturated fat, milk and many components of milk (butterfat, milk protein, calcium from milk, and riboflavin) and total calcium remained positively related to CHD mortality for all 40 countries. There were differences in the consumption of these foods and nutrients in France and Finland. Milk and butterfat (fat from milk, cream, cheese, and butter) consumption was higher in Finland than in France. The consumption of plant foods, recently shown to be protective against CHD (vegetables and vegetable oils containing monounsaturated and polyunsaturated fatty acids), was greater in France than in Finland. CONCLUSIONS: Over the years, France and Finland, with similar intakes of cholesterol and saturated fat, consistently have had very different CHD mortality rates. This paradox may be explained as follows. Given a high intake of cholesterol and saturated fat, the country in which people also consume more plant foods, including small amounts of liquid vegetable oils, and more vegetables (more antioxidants) had lower rates of CHD mortality. On the other hand, milk and butterfat were associated with increased CHD mortality, possibly through their effects on thrombosis as well as on atherosclerosis.

The cholesterol-saturated fat index for coronary prevention: background, use, and a comprehensive table of foods.

The potential of a food or a diet to raise the plasma level of total and low-density-lipoprotein cholesterol and to promote atherosclerosis is directly related to its cholesterol and saturated fat content. A new formula that indicates the concentrations of cholesterol and saturated fat in foods, termed the cholesterol-saturated fat index (CSI), has been devised. A low CSI indicates low saturated fat and/or cholesterol content and thus hypocholesterolemic and low atherogenic potential. Guidelines are provided for using the CSI to evaluate or plan low-fat diets, for comparing a food or a mixed dish with others, and for evaluating a day's food intake. A comprehensive table of foods is presented.

The cholesterol/saturated-fat index: an indication of the hypercholesterolaemic and atherogenic potential of food.

A food's hypercholesterolaemic-atherogenic potential lies in its cholesterol and saturated-fat content. To help understand the contribution of these two factors a cholesterol/saturated-fat index (CSI) has been calculated. This index is based on a modification of a regression equation computed from metabolic studies designed to lower plasma lipids. A low CSI indicates low saturated fat and cholesterol content and low atherogenicity. The CSI may be used to compare different foods and recipes and to evaluate daily intake quickly and easily.