Mechanisms for the Incorporation and Distribution of Radionuclides in Near-Surface Fallout

Fallout is the radioactive glass formed from a mixture of vaporized anthropogenic materials with proximate environmental material. These glassy byproducts constitute a compositional record of environmental materials such as soil and vapor precursors that are responsible for chemical heterogeneity in the glasses. The work of this dissertation is to untangle these different sources of compositional heterogeneity, distinguishing low-abundance vaporized anthropogenic-rich material from natural compositions, in order examine soil behavior and chemical evolution during fallout formation. Unfortunately, mixing convolutes the multivariate elemental relationships in these melts due to overlapping element abundances that might distinguish different source materials and chemical behaviors, making bivariate analysis difficult or impossible to interpret. For these reasons historical and modern studies do not thoroughly investigated how soil affects deposition and incorporation of vaporized material in fallout. This work employs a two-step strategy to overcome these challenges and more effectively understand preserved heterogeneity. First (1), three prospective multivariate approaches are compared: classical least squares (CLS) and principal component analysis (PCA), which are commonly employed in the literature, with Multivariate Curve Resolution Alternating Least Squares (MCR-ALS) that is novel in this application. This analysis shows that a closure and equality constrained MCR-ALS approach succeeds in identifying unrecognized precursor components and is a suitable alternative to PCA, or CLS-style approaches in situations distinguished by limited a priori information of precursor compositions. Second (2), the MCR-ALS method is applied to unbiased spatial analyses from 13 Trinity fallout glasses to resolve the contribution and composition of the environmental or vaporized sources. This numerical approach reveals the importance of environmental precursors such as alkali feldspar, calcite, and quartz, to chemical heterogeneity in most glasses. In contrast to previous studies, however, the work resolves a high Al-Si-rich precursor constituting evidence for volatile loss in the melts. Likewise, an Ca- Fe-Mg-rich composition is also resolved, constituting possible evidence for a vapor source term. Correlation of spatial activity distributions, measured by autoradiography, with the compositional precursors from MCR-ALS in clear evidence supporting surface-driven condensation, wherein molten soil components serve as heterogeneous nucleation sites for the vapor source, agglomeration of small melts onto the surface of larger melts, and physical mixing of the vapor source into the interior of molten objects. This is the first report to provide quantitative model-supported evidence for key mechanisms affecting the composition of the vapor phase in a nuclear event and highlighting the impact of local materials on resultant fallout compositions

MS FT-2-2 7 Orthogonal polynomials and quadrature: Theory, computation, and applications

Quadrature rules find many applications in science and engineering. Their analysis is a classical area of applied mathematics and continues to attract considerable attention. This seminar brings together speakers with expertise in a large variety of quadrature rules. It is the aim of the seminar to provide an overview of recent developments in the analysis of quadrature rules. The computation of error estimates and novel applications also are described

Recent Advances in Single-Particle Tracking: Experiment and Analysis

This Special Issue of Entropy, titled “Recent Advances in Single-Particle Tracking: Experiment and Analysis”, contains a collection of 13 papers concerning different aspects of single-particle tracking, a popular experimental technique that has deeply penetrated molecular biology and statistical and chemical physics. Presenting original research, yet written in an accessible style, this collection will be useful for both newcomers to the field and more experienced researchers looking for some reference. Several papers are written by authorities in the field, and the topics cover aspects of experimental setups, analytical methods of tracking data analysis, a machine learning approach to data and, finally, some more general issues related to diffusion

ESSAYS ON COMPETITIVE PERISHABLE FOOD SUPPLY CHAIN NETWORKS: FROM THE IMPACTS OF TARIFFS AND QUOTAS TO INTEGRATION OF QUALITY

Food, in the form of fresh produce, meat, fish, and/or dairy, is necessary for maintaining life. In this dissertation, I focus on the modeling and analysis of some of the inherent issues in competitive perishable food supply chain networks. I investigate the impacts of trade policies such as tariffs, quotas, and their combination – tariff-rate quotas, as well as the integration of food quality deterioration into food supply chains. The research is especially timely given the prevalence of trade wars and tariffs in todays global political environment. The work is multidisciplinary with constructs from food science integrated into the economics of supply chain networks. The first part of the dissertation overviews the methodological foundations including game theory, network and optimization theory, and variational inequality theory used for the construction and solution of the supply chain network models. In the second part of the dissertation, I first focus on perfectly competitive problems and develop a unified variational inequality framework for spatial price network equilibrium problems with tariff-rate quotas. The accompanying case study on the dairy industry is based on trade between the United States and France. The computational results reveal that tariff-rate quotas may protect domestic producers from foreign competition, but at the expense of higher demand prices for consumers. This work is based on the paper by Nagurney, Besik, and Dong (2019). I then develop an oligopolistic supply chain network equilibrium model with differentiated products consisting of multiple firms, production sites, and demand markets, in which firms compete on product quantities and also quality. I provide a case study on soybeans, an important agricultural product, and investigate different scenarios. Insights as to firm profits and trade volumes, the average product quality, and consumer welfare, are also delineated. Specifically, I find that, although firms may benefit from the imposition of a quota or tariff, the welfare of consumers in the country imposing the quota or tariff declines. This work is based on the paper by Nagurney, Besik, and Li (2019). In the third part of my dissertation, I demonstrate how to incorporate quality deterioration of fresh produce into perishable supply chain network models. I construct an explicit equation for fresh produce quality deterioration based on time and temperature of different pathways in supply chain networks. I first incorporate this feature into local markets in the form of farmers’ markets, which serve as examples of direct to consumer channels and shorter supply chain networks. I also provide a case study of apples in western Massachusetts, under various scenarios, including production disruptions, due to negative weather conditions, resulting in an increase in apple prices at farmers’ markets, a decrease in quality, and a decrease in profits for the apple orchards. These results can be used to inform food firms, policy makers, and regulators. This work is based on the paper by Besik and Nagurney (2017). Subsequently, I develop a competitive food supply chain network model in which the profit-maximizing producers decide not only as to the volume of fresh produce, but they also decide on the initial quality of fresh produce, with associated costs. I incorporate quality deterioration of the fresh produce explicitly with chemical functions depending on time, temperature, and the initial quality of the food product. I then present a case study on peaches, with supply chain disruptions to reveal valuable insights. I find that the disruptions in production result in higher demand prices, and lower initial quality. This is the first such general supply chain network model constructed to include the initial quality of fresh produce. This part of the dissertation is based on the paper by Nagurney, Besik, and Yu (2018)