A life cycle inventory of aluminium die casting

As part of an ongoing project, a life cycle inventory (LCI) of aluminium high pressure die casting (HPDC) has been collected. This has been conducted from the view of an individual product and also the entire process. The objective of the study was to analyse the process and suggest changes to reduce environmental impacts. One modem aluminium high pressure die casting plant located in Victoria, Australia was evaluated and modelled. Site specific data on energy and materials was gathered and the process was modelled using a typical automotive component. The paper also presents our experience and methodology used in this inventory data collection process from the real industry for LCA purposes. The inventory data collected itself reveals that the HPDC process is energy intensive and as such the major emissions were from the use of natural gas fired furnaces and from the brown coal derived electricity. It is also found the large environmental benefits of using secondary aluminium over primary aluminium in the HPDC process. A detailed LCA is being cal1ied out based on the inventory obtained.</div

Funded Pensions, Labor Market Participation, and Economic Growth.

This paper analyses a model of overlapping generations in which agents who do not participate in th elabor market are unable to borrow. Thus an increase in a fully funded pension raises aggregate savings even with a fixed participation rate since private savings are not crowded out one-for-one. When labor force participation is determined endogenously, a rise in the level of fully funded pensions increases the aggregate labor supply. This in turn increases aggregate savings and growth, directly by raising per capita savings and indirectly through tax and interest rate effects.

A computational geometric approach for an ensemble-based topological entropy calculation in two and three dimensions

From the stirring of dye in viscous fluids to the availability of essential nutrients spreading over the surface of a pond, nature is rife with examples of mixing in two-dimensional fluids. The long-time exponential growth rate of a thin filament of dye stretched by the fluid is a well-known proxy for the quality of mixing in two dimensions. This growth rate in turn gives a lower bound on the flow's topological entropy, a measure quantifying the complexity of chaotic dynamics. In the real-world study of mixing, topological entropy may be hard to compute; the velocity field may not be known or may be expensive to recover or approximate, thus limiting our knowledge of the governing system and underlying mechanics driving the mixing. Central to this study are two questions: \emph{How can stretching rates in two-dimensional planar flows best be computed using only trajectory data?}, and \emph{Can a method for computing stretching rates in higher dimensions from only trajectory data be developed?}. In this spirit, we introduce the Ensemble-based Topological Entropy Calculation (E-tec), a method to derive a lower-bound on topological entropy that requires only finite number of system trajectories, like those obtained from ocean drifters, and no detailed knowledge of the velocity field. E-tec is demonstrated to be computationally more efficient than other competing methods in two dimensions that accommodate trajectory data. This is accomplished by considering the evolution of a ``rubber band" wrapped around the data points and evolving with their trajectories. E-tec records the growth of this band as the collective motion of trajectories strike, deform, and stretch it. This exponential growth rate acts as a lower bound on the topological entropy. In this manuscript, I demonstrate convergence of E-tec's approximation with respect to both the number of trajectories (ensemble size) and the duration of trajectories in time. Driving the efficiency of E-tec in two dimensions is the use of computational geometry tools. Not only this, by computing stretching rates in this new computational geometry framework, I extend E-tec to three dimensions using two methods. First, I consider a two-dimensional rubber sheet stretched around a collection of points in a three-dimensional flow. Similar to the band-stretching component of two-dimensional E-tec, a three-dimensional triangulation is used to record the growth of the sheet as it is stretched and deformed by points evolving in time. Second, I calculate the growth rates of one-dimensional rubber strings as they are stretched by the edges of this dynamic, moving triangulation

Topological Chaos in a Three-Dimensional Spherical Fluid Vortex

In chaotic deterministic systems, seemingly stochastic behavior is generated by relatively simple, though hidden, organizing rules and structures. Prominent among the tools used to characterize this complexity in 1D and 2D systems are techniques which exploit the topology of dynamically invariant structures. However, the path to extending many such topological techniques to three dimensions is filled with roadblocks that prevent their application to a wider variety of physical systems. Here, we overcome these roadblocks and successfully analyze a realistic model of 3D fluid advection, by extending the homotopic lobe dynamics (HLD) technique, previously developed for 2D area-preserving dynamics, to 3D volume-preserving dynamics. We start with numerically-generated finite-time chaotic-scattering data for particles entrained in a spherical fluid vortex, and use this data to build a symbolic representation of the dynamics. We then use this symbolic representation to explain and predict the self-similar fractal structure of the scattering data, to compute bounds on the topological entropy, a fundamental measure of mixing, and to discover two different mixing mechanisms, which stretch 2D material surfaces and 1D material curves in distinct ways.Comment: 14 pages, 11 figure

High velocity clouds in nearby disk galaxies

Clouds of neutral hydrogen in our galaxy with the absolute value of v greater than 100 km/s cover approximately 10 percent of the sky to a limiting column density of 1 x 10(exp 18) cm(exp -2). These high velocity clouds (HVCs) may dominate the kinetic energy of neutral hydrogen in non-circular motion, and are an important though poorly understood component of galactic gas. It has been suggested that the HVCs can be reproduced by a combination of three phenomena: a galactic fountain driven by disk supernovae which would account for most of the HVCs, material tidally torn from the Magellanic Clouds, and an outer arm complex which is associated with the large scale structure of the warped galactic disk. We sought to detect HVCs in external galaxies in order to test the galactic fountain model

Spectroscopic Analyses of Excited-State Phenomena in Organized Media: Proton Transfer and Photoisomerization and Measurement of Modified Low Density Lipoproteins Using Rapid-Mixing Multidimensional Stopped-Flow Spectroscopic Methods.

The research presented in this dissertation generally involves aspects of molecular spectroscopy and contains two areas of focus. In the first section, the influences of organized media on the excited-state phenomena of intramolecular proton transfer (ESIPT) and photoisomerization have been investigated. Specifically, the photochemical properties of the novel ESIPT molecule 10-hydroxybenzo(h) quinoline (HBQ), as well as 2-(2\sp\prime-hydroxyphenyl)benzazoles (HBAs), have been examined in the presence of cyclodextrins (CDs) and micelles using absorbance, steady-state, and time-resolved emission spectroscopies. Additionally, the influence of cyclodextrins upon the photoisomerization of trans-stilbene (TS) has been studied. Results from spectroscopic studies of HBQ and HBAs in organized media suggest reduced rates of radiationless transition of the excited tautomer states of these molecules. HBQ exhibits enhanced tautomer emission in both cyclodextrins and micelles through the formation of 1:1 complexes. Moreover, interaction of HBAs with CDs (e.g., $\beta$- and methylated $\beta$-CD\rm\sb{x}) enhance both the ground and excited electronic state (S\sb0 and S\sb1, respectively) intermolecular proton transfer (PT) of two of the HBAs (2-(2\sp\prime-hydroxyphenyl) benzimidazole and -benzothiazole), while enhancing the S\sb0 state intermolecular PT and reducing the S\sb1 state PT rate of 2-(2\sp\prime-hydroxyphenyl)-benzoxazole. Data obtained from induced circular dichroism and time-resolved emission studies are used to further suggest differences in the structural orientation of these molecules in the S\sb0 and S\sb1 states, and the existence of zwitterionic tautomer species of HBAs, respectively. In the case of trans-stilbene, a dual fluorescence is observed for the molecule in ternary aqueous solutions of $\gamma$-cyclodextrin ($\gamma$-CD\rm\sb{x}). The ternary component (cyclohexane or toluene) plays an active role in increasing the excimer emission of the molecule through the formation of ternary complexes that restrict the photoisomerization of trans-stilbene in the cyclodextrin cavity. The results from time-resolved emission and anisotropy studies further support the formation of extended linear aggregates of trans-stilbene:$\gamma$-CD\rm\sb{x} with these components. The second section of this dissertation concerns the development of analytical assays for modified low-density lipoproteins (LDLs) using multidimensional stopped-flow (SF) spectrophotometric methods. Specifically, SF assays for lipid peroxides have been developed using triiodide and indigo carmine dye as chromophores. The data obtained are used to assess the suitability of these assays for modified LDLs

Evaluating Prescription Drug Subsidies for Diabetics: Effects on Medication Adherence and Health Outcomes

"Out-of-pocket drug costs are rising at a rapid rate, including for insulin, a life-saving drug used by 3.1 million diabetics on Medicare. High out-of-pocket drug costs place an accentuated burden on people with diabetes, many of whom have low incomes, prompting debate about how to address the growing cost burden of prescription drugs for vulnerable populations. In this project, we propose to evaluate the impact of prescription drug subsidies provided through the Medicare Part D Low-Income Subsidy (LIS) program, which reduces prescription drug co-pays and caps out-of-pocket costs for the program’s lowest-income recipients. Our study will employ a quasi-experimental regression discontinuity (RD) study design to quantify the impacts of the LIS among low-income Medicare beneficiaries with diabetes. Specifically, our RD design will compare diabetic beneficiaries whose income is below LIS eligibility thresholds, who are either fully or largely insulated from rising out-of-pocket drug costs, to diabetic beneficiaries whose income is slightly above these eligibility thresholds, who pay a much larger proportion of prescription drug costs out of pocket and have no limit on their Part D out-of-pocket spending. We will examine whether sizeable differences in out-of-pocket costs associated with these LIS eligibility thresholds are linked to differences in medication adherence and diabetes-related hospitalizations. Thus, our research will provide new evidence about the consequences of high out-of-pocket drug costs for low-income, chronically ill patients and the LIS’s effectiveness in mitigating these costs. This study builds on the co-investigators’ research expertise in pharmaceutical pricing, health insurance policy, and health economics. Seed funds provided through this grant will allow us to pilot our proposed RD design in a large, clinically and economically vulnerable population, establishing the feasibility of our methods to support future extramurally funded research examining policies to improve prescription drug affordability for low-income, aging, and disabled populations.