On Demand Nanoscale Phase Manipulation of Vanadium Dioxide by Scanning Probe Lithography

This dissertation focuses on nanoscale phase manipulations of Vanadium Dioxide. Nanoscale control of material properties is a current obstacle for the next generation of optoelectronic and photonic devices. Vanadium Dioxide is a strongly correlated material with an insulator-metal phase transition at approximately 345 K that generates dramatic electronic and optical property changes. However, the development of industry device application based on this phenomenon has been limited thus far due to the macroscopic scale and the volatile nature of the phase transition. In this work these limitations are assessed and circumvented. A home-built, variable temperature, scanning near-field optical microscope was engineered for Vanadium Dioxide manipulations and detections. Using this instrument, various scanning probe lithography based methods are implemented to induce new nanoscale phases. Three new phase transitions are discovered; a monoclinic metallic at the nanoscale, a rutile metallic metastable phase, and a van der Waals layered insulator. These new phases are studied and characterized to further understand phase manipulations in strongly correlated materials. One of the new phase transitions, monoclinic metallic, showcases plasmonic excitations. This phenomenon is used to demonstrate various nanoplasmonic devices such as rewritable waveguides, spatially modulated resonators, and reconfigurable planar optics. Finally, Oxygen Vacancy diffusion of the monoclinic structure is monitored to determine the temporal limitation for device applications. The discovery, demonstration, and study of these phases clearly shows the ability to manipulate Vanadium Dioxide on the nanoscale for the first time. Phase control is accomplished under ambient conditions and is stable over long periods of time. This technology opens the door for multifunctional device application using strongly correlated materials

Irrigation Costs and Prices: An Institutional Economic Analysis of Pricing Strategies in the Office Du Niger and Small Pump-Irrigated Village Perimeters in Mali

This paper explores the link between cost and price in two irrigation schemes in Mali - the Office du Niger (ON), a large-scale gravity irrigation authority, and a number of small pump-irrigated fields at village perimeters along the Niger River (Petits Perimetres d'Irrigation Villagois). I argue that the effectiveness of cost-recovery pricing strategies for improving the long-run financial sustainability of irrigation systems and advancing national development objectives is a function of decision-making processes, which influence the distribution and absolute levels of cost and benefit flows. Participants' willingness and capacity to invest in problem solving play an important part in irrigation system viability by increasing the rate of technological and institutional change, which can increase benefits and decrease costs of production. Understanding formal and informal relationships between service users and service providers can help reveal institution-based sources of incentives and disincentives for parties to invest in producing effort and solving problems. The paper examines the price strategies in two case studies and the relationships among stakeholders in the design and implementation of each system's price strategies. Institutional theory suggests ways to align individual incentives with the objectives of the pricing strategy; targeted investments may be needed to provide participants with the means to act on institutionally designed incentives.Farm Management,

Effect of different income housing zones on effluent quality of Biofil toilet waste digesters in Accra, Ghana

This study was carried out to assess the effect of different income-housing zones on the quality of effluent from standard Biofil® toilet waste digesters in Accra, Ghana. Records of the digesters installed were obtained from BiofilCom and were sorted out into income-housing zones (low, middle and high income housing zones). In all, 36 toilet digesters were found accessible and sampled 3 times each for effluent. Samples were analyzed for E. coli, Total coliform, helminth eggs, BOD, TSS, NH3-N and PO4-P, using standard methods. Results show that effluent quality exceeded the requirements set by Ghana EPA for discharge into water bodies. However, high removal efficiencies were obtained for BOD (84%) and TSS (82%). In most cases, the pollutant concentrations were significantly higher in effluents from the high-income zones than in the middle and low income zones

A Transdisciplinary Approach to Managing Emerging and Resurging Mosquito-Borne Diseases in the Western Pacific Region

Mosquitoes transmit a number of harmful diseases that have an impact on local communities and visitors, and many pose a threat to neighboring countries. As federal monitoring budgets shrink across the world, the increasing importance of citizen scientists in monitoring and identifying invasive species, as well as acting to prevent these diseases, are discussed. Examples of past mosquito management programs are provided, and future directions are discussed with an emphasis on the Western Pacific Region

Multiferroic BaCoF4 in Thin Film Form: Ferroelectricity, Magnetic Ordering, and Strain

Multiferroic materials have simultaneous magnetic and ferroelectric long-range orders and can be potentially useful for a wide range of applications. Conventional ferroelectricity in oxide perovskites favors nonmagnetic electronic configurations of transition metal ions, thus limiting the number of intrinsic multiferroic materials. On the other hand, this is not necessarily true for multiferroic fluorides. Using molecular beam epitaxy, we demonstrate for the first time that the multiferroic orthorhombic fluoride BaCoF4 can be synthesized in thin film form. Ferroelectric hysteresis measurements and piezoresponse force microscopy show that the films are indeed ferroelectric. From structural information, magnetic measurements, and first-principles calculations, a modified magnetic ground state is identified which can be represented as a combination of bulk collinear antiferromagnetism with two additional canted spin orders oriented along orthogonal axes of the BaCoF4 unit cell. The calculations indicate that an anisotropic epitaxial strain is responsible for this unusual magnetic ground state

Improving community health through marketing exchanges: A participatory action research study on water, sanitation, and hygiene in three Melanesian countries

Diseases related to poor water, sanitation and hygiene (WaSH) are major causes of mortality and morbidity. While pursuing marketing approaches to WaSH to improve health outcomes is often narrowly associated with monetary exchange, marketing theory recognises four broad marketing exchange archetypes: market-based, non-market-based, command-based and culturally determined. This diversity reflects the need for parameters broader than monetary exchange when improving WaSH. This study applied a participatory action research process to investigate how impoverished communities in Melanesian urban and peri-urban informal settlements attempt to meet their WaSH needs through marketing exchange. Exchanges of all four archetypes were present, often in combination. Motivations for participating in the marketing exchanges were based on social relationships alongside WaSH needs, health aspirations and financial circumstances. By leveraging these motivations and pre-existing, self-determined marketing exchanges, WaSH practitioners may be able to foster WaSH marketing exchanges consistent with local context and capabilities, in turn improving community physical, mental and social health

Measuring the Impacts of Health Care on Rural Counties: Hospitals and Clinics in Preston County

Quality health care systems are important to a community’s health interests, but they also play an important role in a community’s economic vitality. This paper reviews somecontemporary challenges facing rural health care systems due to changes in the health care industry, the health insurance industry, the national economy, and reforms of social benefitprograms. Using Preston County, West Virginia as a case study, the paper illustrates the link between rural economic vitality and quality, accessible healthcare systems. Furthermore, thispaper demonstrates the need for active community involvement in local health care decisionmaking processes. It also provides a variety of methods that can be used to measure the economic impacts of health care systems in a rural county using the IMPLAN input-output program using Preston County hospitals and clinics as a case study

Design of Scattering Scanning Near-Field Optical Microscope

The primary objective of this work is to construct a fully functional scattering type Scanning Near-field Optical Microscope (s-SNOM), and to understand the working mechanisms behind it. An s-SNOM is an instrument made up of two separate instruments working in unison. One instrument is a scanning optical microscope focusing light onto a raster scanning sample surface combined with an interferometer set up. The second instrument is an Atomic Force Microscope (AFM) operating in noncontact mode. The AFM uses a small probe that interacts with the raster scanning sample surface to map out the topography of the of the sample surface. An s-SNOM uses both of these instruments simultaneously by focusing the light of the optical microscope onto the probe of the AFM. This probe acts as a nano-antenna and confines the light allowing for light-matter interaction to be inferred far below the resolution of the diffraction limit of light. This specific s-SNOM system is unique to others by having a controllable environment. It is high vacuum compatible and variable temperature. In addition, it is efficient at collecting scattered light due to the focusing objective being a partial elliptical mirror which collects 360° of light around the major axis. This s-SNOM system will be used for direct imaging of surface plasmons. Intended works are inducing surface plasmons on InSe thin films, and seeing the enhancement effect of introducing Au nano-rods. Also dielectric properties of materials will be interpreted such as the metal to insulator phase transition of NbO2

Irrigation Costs and Prices: An Institutional Economic Analysis of Pricing Strategies in the Office Du Niger and Small Pump-Irrigated Village Perimeters in Mali

This paper explores the link between cost and price in two irrigation schemes in Mali - the Office du Niger (ON), a large-scale gravity irrigation authority, and a number of small pump-irrigated fields at village perimeters along the Niger River (Petits Perimetres d'Irrigation Villagois). I argue that the effectiveness of cost-recovery pricing strategies for improving the long-run financial sustainability of irrigation systems and advancing national development objectives is a function of decision-making processes, which influence the distribution and absolute levels of cost and benefit flows. Participants' willingness and capacity to invest in problem solving play an important part in irrigation system viability by increasing the rate of technological and institutional change, which can increase benefits and decrease costs of production. Understanding formal and informal relationships between service users and service providers can help reveal institution-based sources of incentives and disincentives for parties to invest in producing effort and solving problems. The paper examines the price strategies in two case studies and the relationships among stakeholders in the design and implementation of each system's price strategies. Institutional theory suggests ways to align individual incentives with the objectives of the pricing strategy; targeted investments may be needed to provide participants with the means to act on institutionally designed incentives

Performance evaluation of bio l toilet waste digester technologies in Ghana: the ef cacy of ef uent treatment options

The study was carried out to assess the ef cacy of a standard Bio l toilet digester with regard to its ef uentqualityandtoevaluatetheperformanceofnewef uentpolishingoptionsbeingdeveloped by Bio lCom. In uent and ef uent were collected from 18 standard Bio l digesters connected to full- ush toilets. Ef uent from ve pilot installations with improved ef uent polishing options were also taken for analyses. Ten other Bio l installations were selected to assess the impact of digester ef uent discharge on the surrounding soil. Pollutant concentrations in the Bio l ef uent exceeded both Ghana EPA and WHO standards for discharge though pollutant removal ef ciencies were high: 84% for biochemical oxygen demand, 86.1% for chemical oxygen demand and 82.4% for total suspended solids. Escherichia coli and total coliform levels were signi cantly reduced by 63% and 95.6%, respectively, and nutrients were the least removed from ef uents. Generally, ef uents from the majority of the pilot polishing options met most of the discharge standards. E. coli were present in the soil at all study sites, except one. Bio l digester ef uent is discharged subsurface but comparing their ef uent quality with standards for discharge into water courses is relevant especially in areas of frequent ooding and high water tables