Novel metallic and insulating states at a bent quantum Hall junction

A non-planar geometry for the quantum Hall (QH) effect is studied, whereby two quantum Hall (QH) systems are joined at a sharp right angle. When both facets are at equal filling factor nu the junction hosts a channel with non-quantized conductance, dependent on nu. The state is metallic at nu = 1/3, with conductance along the junction increasing as the temperature T drops. At nu = 1, 2 it is strongly insulating, and at nu = 3, 4 shows only weak T dependence. Upon applying a dc voltage bias along the junction, the differential conductance again shows three different behaviors. Hartree calculations of the dispersion at the junction illustrate possible explanations, and differences from planar QH structures are highlighted.Comment: 5 pages, 4 figures, text + figs revised for clarit

Mathematical analysis for the performance assessment of space communication parameters, IBM-360 version

Development of equations to determine communication capability of pulse or digital transmission link is discussed. Equation specifies probability detection error for one-way transmission. Analysis is conducted on IBM 360 computer using FORTRAN 4

Vermont Global Warming Solutions Act: The Costs of Inaction from Land Conversions

The Vermont (VT) Global Warming Solutions Act (GWSA, 2020) sets greenhouse gas (GHG) emissions reduction targets as 26% below 2005 by 2025, 40% below 1990 by 2030 and 80% below 1990 by 2050 for energy-related emissions only. Vermont’s omission of GHG emissions from land conversions can result in significant costs of inaction (COI), which can hinder state’s mitigation and adaptation plans and result in a climate crisis-related risks (e.g., credit downgrade). Science-based spatio-temporal data of GHG emissions from soils as a result of land conversions can be integrated into the conceptual framework of “action” versus “inaction” to prevent GHG emissions. The application of soil information data and remote sensing analysis can identify the GHG emissions from land conversions, which can be expressed as “realized” social costs of “inaction”. This study demonstrates the rapid assessment of the value of regulating ecosystems services (ES) from soil organic carbon (SOC), soil inorganic carbon (SIC), and total soil carbon (TSC) stocks, based on the concept of the avoided social cost of carbon dioxide (CO2) emissions for VT by soil order and county using remote sensing and information from the State Soil Geographic (STATSGO) and Soil Survey Geographic Database (SSURGO) databases. Classified land cover data for 2001 and 2016 were downloaded from the Multi-Resolution Land Characteristics Consortium (MRLC) website. These results provide accurate and quantitative spatio-temporal information about likely GHG emissions, which can be linked to VT’s climate action plan. A failure to considerably reduce emissions from land conversions in the future may need even larger reductions in the future and would increase climate change costs to VT and beyond its borders

ESSAYS ON THE ROLE OF GOVERNMENT REGULATION AND POLICY IN HEALTH CARE MARKETS

Understanding how health care markets function is important not only because competition has a direct influence on the price and utilization of health care services, but also because the proper functioning, or lack thereof, of health care markets has a very real impact on patients who depend on health care markets and providers for their personal well-being. In this dissertation, I examine the role of government policies and regulation in health care markets, with a focus on the response of health care providers. In Chapter 1, I analyze the impact of Medicare payment rules on hospital ownership of physician practices. Since the mid-2000’s, there has been a rapid increase in hospital ownership of physician practices, however, there is little empirical research which addresses the causes of this recent wave of integration. Medicare’s “provider-based” billing policy allows hospital-owned physician practices to charge higher reimbursement rates for services provided compared to a freestanding, independent physician practice, without altering how or where services are provided. This “site-based” differential creates a premium for physicians to integrate with hospitals, and the size of this differential varies with the types of health care services provided. I find that Medicare payment rules have contributed to hospital ownership of physician practices and that the response varies across physician specialties. A 10 percent increase in the relative reimbursement rate paid to integrated physicians leads to a 1.9 percentage point increase in the probability of hospital ownership for Medical Care specialties, including cardiology, neurology, and dermatology, which explains about one-third of observed integration of these specialties from 2005 through 2015. Magnitudes for Surgical Care specialties are similar, but more sensitive across specifications. There is no significant response for Primary Care physicians. In combination with other empirical literature which finds that integration between physicians and hospitals typically results in higher prices with no impact on costs or quality of care, I cautiously interpret this responsiveness as evidence that Medicare’s provider-based billing policy overcompensates integrated physician practices and leads to an inefficiently high level of vertical integration between physician and hospitals. In Chapter 2, I analyze the effect of anti-fraud enforcement activity on Medicaid spending, with a particular focus on the False Claims Act. The False Claims Act (FCA) is a federal statute which protects the government from making undeserved payments to contractors and suppliers. Individual states have chosen to enact their own versions of the federal FCA, and these statutes have increasingly been used to target health care fraud. FCA statutes commonly include substantial monetary penalties such as “per-violation” monetary fines and tripled damages, as well as a “whistleblower” provision which allows private plaintiffs to initiate a lawsuit and collect a portion of recoveries as a reward. Using variation in statelevel FCA legislation, I find state FCAs reduce Medicaid prescription drug spending by 21 percent, while other spending categories - which are less lucrative for FCA lawsuits - are unresponsive. Within the prescription drug category, drugs prone to off-label use show larger declines in response to the whistleblower laws, consistent with FCA lawsuits being used to prosecute pharmaceutical manufacturers for off-label marketing and promotion. Spending and prescription volume for drugs prone to off-label use fall by up to 14 percent. This effect could be driven by pharmaceutical manufacturers’ changes in physician detailing for drugs prone to off-label use and/or physicians’ changes in prescribing behavior

Measuring carrier density in parallel conduction layers of quantum Hall systems

An experimental analysis for two parallel conducting layers determines the full resistivity tensor of the parallel layer, at magnetic fields where the other layer is in the quantum Hall regime. In heterostructures which exhibit parallel conduction in the modulation-doped layer, this analysis quantitatively determines the charge density in the doping layer and can be used to estimate the mobility. To illustrate one application, experimental data show magnetic freeze-out of parallel conduction in a modulation doped heterojunction. As another example, the carrier density of a minimally populated second subband in a two-subband quantum well is determined. A simple formula is derived that can estimate the carrier density in a highly resistive parallel layer from a single Hall measurement of the total system.Comment: 7 pages, 7 figure

Up-converted Emissions of Er3+ Doped Gd2(WO4)3 Phosphors

In this work, the up-conversion (UC) emissions of Er3+ in a gadolinium tungstate host was investigated to analyze the possible processes of up-conversion by 1500 nm and 980 nm excitation. Studies were conducted to see how the 4S3/2 -\u3e 4I15/2 transition changed with varying current through the excitation source, varying excitation wavelength, and doping concentration. Power dependent studies revealed that under 1500 nm excitation the 4S3/2 -\u3e 4I15/2 transition needed 3 photons, while 980 nm excitation could do the same transition with 2 photons. It was found that 1500 nm could produce more efficient red emission due to the 4I9/2 -\u3e 4I15/2 transition only needing 2 photons. Concentration dependence studies revealed many trends of how up-conversion processes varied with erbium ion separation. The number of photons used to UC 980 nm decreases as concentration increases, meaning that the mechanism depends on energy transfer UC and the inefficiency of green emissions at higher concentration is due to concentration quenching. UC of 1500 nm also uses less photons as concentration increases; red and green emissions are not as dependent on energy transfer UC as 980 nm UC. Also, as concentration increases past the point least photon use, the erbium ions start cross relaxing causing the number of photons used to increase rapidly. It was found that even after cross relaxation becomes the dominant UC process, the intensity still increases as concentration increases until a point where quenching starts to take effect

Inertial Upper Stage (IUS) software analysis

The Inertial Upper Stage (IUS) System, an extension of the Space Transportation System (STS) operating regime to include higher orbits, orbital plane changes, geosynchronous orbits, and interplanetary trajectories is presented. The IUS software design, the IUS software interfaces with other systems, and the cost effectiveness in software verification are described. Tasks of the IUS discussed include: (1) design analysis; (2) validation requirements analysis; (3) interface analysis; and (4) requirements analysis

Potential effects of the introduction of the discrete address beacon system data link on air/ground information transfer problems

This study of Aviation Safety Reporting System reports suggests that benefits should accure from implementation of discrete address beacon system data link. The phase enhanced terminal information system service is expected to provide better terminal information than present systems by improving currency and accuracy. In the exchange of air traffic control messages, discrete address insures that only the intended recipient receives and acts on a specific message. Visual displays and printer copy of messages should mitigate many of the reported problems associated with voice communications. The problems that remain unaffected include error in addressing the intended recipient and messages whose content is wrong but are otherwise correct as to format and reasonableness