Patterns in the Sand: Mathematical Exploration of Chladni Patterns

Chladni Patterns are formed when sand settles at the nodes of two dimensional standing waves, excited on a metallic plate which is driven at a resonant frequency. By considering a two-dimensional rectangular membrane with fixed boundary and constant density as an idealized model of the metal plate, a formula for predicting the Chladni Patterns that will form at certain frequencies can be found. In addition to mathematically exploring these mysterious patterns, I have created my own “Chladni Patterns” in the lab

SHAP Enrollment and Eligibility Activities: Implications for Process and System Modernization Under National Health Reform

Shares five states' experiences and best practices in using State Health Access Program grants to expand public health coverage through community-based outreach and improved eligibility and enrollment processes, as well as implications for federal reform

Inter-temporal differences in the income elasticity of demand for lottery tickets

We estimate annual income elasticities of demand for lottery tickets using roughly twenty years of county-level data for three states. We find that the income elasticity of demand (and thus the tax burden) for lottery tickets has changed over time. We argue that these changes are due to changes in a state's lottery game portfolio and the growth in consumer income. Trends in the income elasticity of demand for instant and online lottery games appear to be different. Our results question the long-term growth potential of lottery revenue and have policy implications for state governments and those concerned about regressivity.Gambling industry ; Income

Income and lottery sales: transfers trump income from work and wealth

Previous studies have examined the effect of income on lottery ticket expenditures using an aggregate measure of income, usually personal income. Reasons exist, however, for believing that lottery expenditures do not respond equally to all sources of income. This paper examines the propensity to purchase lottery tickets from separate types of income, namely income from earnings, transfer payments, and wealth. Using county-level data for five states, we find evidence that lottery expenditures respond differently to changes in each income type, and that ticket purchases are most strongly influenced by changes in transfer payments. Several policy implications follow from our results.Income ; Gambling industry

Charge delocalization characteristics of regioregular high mobility polymers.

Controlling the regioregularity among the structural units of narrow bandgap conjugated polymer backbones has led to improvements in optoelectronic properties, for example in the mobilities observed in field effect transistor devices. To investigate how the regioregularity affects quantities relevant to hole transport, regioregular and regiorandom oligomers representative of polymeric structures were studied using density functional theory. Several structural and electronic characteristics of the oligomers were compared, including chain planarity, cation spin density, excess charges on molecular units and internal reorganizational energy. The main difference between the regioregular and regiorandom oligomers is found to be the conjugated backbone planarity, while the reorganizational energies calculated are quite similar across the molecular family. This work constitutes the first step on understanding the complex interplay of atomistic changes and an oligomer backbone structure toward modeling the charge transport properties

Spatial dependence in models of state fiscal policy convergence

We apply spatial econometric techniques to models of state and local fiscal policy convergence. Total tax revenue and expenditures, as well as broad tax and expenditure categories, of state and local governments in each of the 48 contiguous U.S. states are examined. We extend work by Scully (1991) and Annala (2003) in much the same way that Rey and Montouri (1999) extended the literature dealing with income convergence among U.S. states. Our results indicate that most fiscal policies have been converging and exhibit spatial dependence. A more specific interpretation of our general spatial results is that the finding of spatial dependence indicates that the growth paths of state and local fiscal policies are not independent. In addition, we find that total expenditures have been converging faster than output, whereas total tax revenues have been converging slower that output. Our models further demonstrate that state expenditure growth is dependent upon expenditure growth in economically and demographically similar states, while output growth and revenue growth in a state are dependent on output growth and revenue growth, respectively, in contiguous states.Fiscal policy

Developing a case for the implementation of a control augmentation system to improve flying qualities in the EA-6B aircraft

The EA-6B aircraft was designed and built in the late 1960s by the Grumman Aerospace Corporation for the United States Navy and Marine Corps to be used as a tactical electronic warfare (EW) platform. High losses of U.S. attack aircraft to surface-to- air missiles (SAMs) in Southeast Asia led to the requirement for a carrier-based tactical aircraft capable of providing EW support in the form of electronic jamming in support of strike aircraft. The EA-6B became the aircraft that fulfilled the EW requirement. Forty years have passed since the introduction of the EA-6B and the demand for the tactical EW capability continues to increase. Meeting these requirements has taken a toll oh the aircraft\u27s wing fatigue life, and has produced a shortage of the aircraft\u27s Automatic Flight Control System (AFCS) computer. The replacement computer contracted to correct the current problem of the aging analog AFCS computer is an up-to-date digital flight control computer (Model EA-6B Aircraft Program, 1995). The implementation of this computer will allow greater processing power and should be used to the full extent of its capability. An up-to-date flight control computer will cost less to repair, be readily replaceable, and will improve mission readiness and safety of flight. This thesis will build a case to use the additional processing power of the replacement digital flight control computer to improve flying qualities through a Control Augmentation System (CAS) that should have the effect in the following areas; 1. Limit accelerations during flight and thereby control the current problem of Fatigue Life Expenditure (FLE). 2. Improve flying qualities, specifically in the landing configuration with an emphasis to improve shipboard operations. With the current SAS the aircraft demonstrates less than satisfactory flying qualities in all axes (lateral, directional, and longitudinal) and configurations. 3. Limit Angle of Attack (AOA) in certain abnormal configurations, that are commonly encountered in the EA-6B, due to the aging airframe. The configuration that is particularly dangerous is the no slat-flaps down approach. This approach requires the pilot to maintain AGA precisely. The consequences of slowing one degree (equivalent to approximately 2 KIAS) below the recommended approach AGA will result in an uncontrollable pitch up (longitudinal instability) and subsequent departure from controlled flight (mandatory ejection criteria in this configuration) (EA-6B NATOPS Flight Manual, 1997). 4. Improve departure resistance by limiting angle of attack and controlling side-slip. Jamming pods are on all wing stations when the airplane is in the normal configuration. Departures that develop into spins frequently result in loss of the aircraft due to large inertia, forces, caused by the weight of the stores carried on the wings stations, which can not be overcome by the aerodynamic forces required for recovery

Spatial probit and the geographic patterns of state lotteries

We implement a spatial probit model to differentiate states with a lottery from those without a lottery. Our analysis extends the basic spatial probit model by allowing spatial dependence to vary across geographic regions. We also separate the spatial effects of neighbors versus non-neighbors. The methodology provides consistent and efficient coefficient estimation in light of the simultaneity in spatial dependence. We find evidence of spatial dependence and spatial heterogeneity in lottery usage, and we find that spatial patterns differ significantly by geographic region. The importance of spatial dependence in state lottery usage suggests the need to consider spatial effects in empirical models examining the use of any policy tool by subnational governmental units.Regional economics

The geography, economics, and politics of lottery adoption

Since New Hampshire introduced the first modern state-sponsored lottery in 1964, 41 other states plus the District of Columbia have adopted lotteries. Lottery ticket sales in the United States topped $48 billion in 2004, with state governments reaping nearly$14 billion in net lottery revenue. In this paper the authors attempt to answer the question of why some states have adopted lotteries and others have not. First, they establish a framework for analyzing the determination of public policies that highlights the roles of individual voters, interest groups, and politicians within a state as well as the influence of policies in neighboring states. The authors then introduce some general explanations for the adoption of a new tax that stress the role of economic development, fiscal health, election cycles, political parties, and geography. Next, because the lottery adoption decision is more than simply a tax decision, a number of factors specific to this decision are identified. State income, lottery adoption by neighboring states, the timing of elections, and the role of organized interest groups, especially the opposition of certain religious organizations, are significant factors explaining lottery adoption.Gambling industry