No description available.

The objective of this thesis was to select a star for observation and determine the error in the retrieval technique for a rocket experiment to measure lower thermospheric Nitric Oxide in the polar night using stellar occultation technique. These objectives are accomplished by planning the geometry, determining the requirements for observations, window for launch and discussing the retrieval technique. The planning is carried out using an approximated (no drag) and simulated rocket trajectory (provided by NSROC: NASA Rocket Operations Contract). The simulation for the retrievals is done using data from Student Nitric Oxide Explorer. Stars were taken from a catalogue called TD1. Launch times were obtained from the geometry planned resulting from selecting a zenith angle after choosing a maximum occultation height and determining rocket apogee. Window for observing Spica was found to be 20 minutes. The retrieval technique and simulations showed that column densities and volume densities should be retrievable to less than 5% and 20% respectively observing occultation heights 90-120km. The study suggests that choosing a star positioned north w.r.t the observation location gives us more poleward latitudes and larger launch window. Future research can be carried out applying the stellar occultation and retrieval technique to a satellite. / Master of Science

A major challenge in agroecosystems is how to manage the systems so that it reduces crop pests and enhances natural pest control. This thesis investigates patterns of crop pests and top-down effects of birds and arthropod predators in relation to land-use composition across spatial scales. In paper (I) I examined the crop distribution and land-use types in relation to the crop raiding patterns in 15 transectsin sites close to and far from forests along with a questionnaire survey at household level. I found severe crop raiding close to forests, but it had no impact on crop composition growing between the two sites. In paper (II) I examined the effect of forest and tree cover, at local and landscape scales, on the abundance of arthropod predators by collecting specimens from 40 home gardens. My result showed higher abundance of arthropod predators when either the home garden or the surroundings had a high tree-cover, compared to when tree-cover at both scales was similarly either high or low. In paper (III) I investigated the effect of excluding birds and arthropod predators on leaf damage on rape seed in 26 home gardens. I found stronger top-down impacts from arthropod predators on crop pests in tree-poor gardens than in tree-rich gardens. There was no effect of birds. In paper (IV) I explored the effect of landscape complexity on bird and arthropod predation using plasticine caterpillars in 36 home gardens across landscapes. The rate of arthropod predation on caterpillars was higher in simple than in complex landscapes. The rate of bird predation did not vary between complex and simple landscapes. In simple landscapes, arthropod predation was higher than that of birds. The overall results suggest that simplified gardens/landscapes still have enough habitat heterogeneity to support arthropod predators for the significant top-down controlling effect on crop pests. However, I did not find clear effect of complexityon the top-down effect of birds. / <p>At the time of the doctoral defence the following papers were unpublished and had a status as follows: Paper 1: Manuscript; Paper 3: Manuscript; Paper 4: Manuscript</p>

Master of Science / Department of Agricultural Economics / Hikaru H. Peterson / This study investigates consumers’ preferences for organic baby meals. The growth of the U.S organic industry has been notable during the last two decades. The U.S. organic farmers do not produce enough quantity to meet the increasing U.S demand for organic food, and increasingly more organic foods are manufactured from organic ingredients produced outside the U.S. Tensions have emerged in the organic sectors as large-scale companies have seized opportunities to sell products differentiated with the organic label. The study aimed to estimate U.S. consumers’ willingness to pay (WTP) for selected attributes (type of brand, production attributes, and origin of ingredients) of baby meal products using a choice-based conjoint analysis. The organic offerings represent a nontrivial share of this market. In recent years, offerings under store brands have also been increasing. The study identified that consumers preferred a major national brand with a large market share such as Gerber (80%) to the other types of brands including store brands. In terms of product characteristics, pesticide free and non-GMO products were seen as consumers’ top priorities. Consumers would not buy products that did not exhibit these two characteristics. Minimally processed products seemed not to matter for the majority of consumers, and these products (sold frozen) were expected to be a niche market. Besides, a product made with U.S ingredients (organically or non-organically grown) was associated with a higher utility. Firms can run a cost-benefit analysis to see if sourcing U.S. ingredients could increase profit. Running experimental auctions are recommended to firms that want to elicit WTP for U.S grown ingredients and implement an efficient marketing strategy. This study is a preliminary analysis that highlighted consumers’ preferences in the baby food market, and future analysis would complement the findings.

No description available.

Master of Science / Department of Agricultural Economics / Hikaru H. Peterson / Alexander E. Saak / Notable changes are occurring in the U.S. organic food sector. First, the U.S. organic food system is increasingly relying on imports, because the expansion in the organic production has failed to satisfactorily meet the rapidly growing demand for organic foods. Second, the “locally grown” concept has become appealing to consumers, with some evidence of consumers switching from certified organic foods to local, conventional foods. Third, organic food has penetrated the mass-market channel, and organic foods are no longer being sold exclusively in natural product stores. And fourth, the social and environmental awareness among consumers is increasing. Thus, consumers are also willing to pay a price premium to support small farmers. To understand how these changes are affecting the demand for organic foods, this study used survey data to assess U.S. consumers‟ preferences for fresh organic apples that are sourced from various places and from supply chain operations that vary in scale. The survey was administered via the Internet to a random sample of 285 households across the U.S through a research company. Choice experiment was selected as the valuation method. Results indicate that among the levels of the location attributes, the “locally grown” label was associated with the highest average WTP. The “regionally grown” was the second most preferred, “U.S. grown” the third, and “imported” the least. The “locally grown” label was valued higher than the “certified organic label”. Also, consumers were willing to pay a higher value for apples produced on a small farm compared to those from a large farm. However, they did not distinguish the type of retail outlets where apples were offered. The analysis incorporating the effects of consumer characteristics suggest that the perceived importance of public benefits impacted the values of origin attributes more than the private ones; the type of retail outlet attributes became significant among certain gender and age segments; and the value of small farm attribute increased with consumers‟ income. Finally, results from a theoretical model suggest that the variability in the WTP obtained among the origin attributes could be explained by the reputation of product quality depending on their origin.

This study uses a predominantly quantitative approach to explore the effect of different error correction feedback mechanisms on students’ English as a Second Language writing (narrative and descriptive) amongst high school students in Botswana. A longitudinal, quasi-experimental design is used, with a control group that received no correction feedback while the experimental groups received direct, coded and uncoded feedback. Three hypotheses define the study in terms of fluency, correction success and accuracy development over time. No significant increases in fluency were found between the pretests and posttests. Correction success achieved by the three treatment groups when rewriting texts reflected the explicitness of the feedback, with the direct group highest, followed by the coded and uncoded groups. Findings were mixed on the important issue of accuracy development, although they strongly suggest that for spelling, any type of feedback is significantly better than none and that coded feedback is better than direct feedback despite the latter being more explicit. Students from all the treatment groups expressed similarly positive opinions on correction feedback. / Applied Language / M.A. (Spec. in Applied Linguistics)

Text in Afrikaans, abstract in Afrikaans and English / As deel van die weermodifikasie-eksperiment in Bethlehem, Suid-Afiika, is 'n reenmeternetwerk geinstalleer, en word die neerslagwaardes R; wat by 43 reenmeterstasies waargeneem is, vergelyk met die waargenome radar reflektiwiteit Z;. Alhoewel radar ruimtelike en tydskontinue metings van reflektiwiteit bied wat onmiddellik by een sentrale punt beskikbaar is, is die akkuraatheid van radar om reenval te meet onseker as gevolg van verskeie potensiele foute in die omskakeling van reflektiwiteit na reenval. Dit word aanvaar dat reenmeters akkurate puntwaarnemings van reenval gee en daar bestaan eenstemmigheid dat die kombinasie van die twee metodes beter is as enigeen van die metodes afsonderlik. In hierdie studie ondersoek ek die toepassing van die veralgemeende lineere model as 'n beramingstegniek. Vorige studies gebruik die log-log transformasie, d. w.s. logZ = logA + b(logR) van die Z = ARb verwantskap om die koeffisiente A en b met behulp van kleinste-kwadrate-regressie te bepaal. Die implisiete aanname hiermee is dat die foute ongekorreleerd is. Met die inverse verwantskap R = czd d.w.s. logR = logC + d(logZ) neem ek aan dat die waarnemings nie onafhanklik is nie sodat die regressiekoeffisiente bereken word met behulp van die metode van die veralgemeende lineere model. Om die ruimtelike afhanklikheid van die reenmeterwaarnemings te modelleer, word eksperimentele variogramme uit die data bereken en gepas met teoretiese variogramme wat gebruik word om die variansie-kovariansiematriks te vu!. "Gemiddeld" vaar hierdie metode beter as gewone regressie vir analises wat reenmeters wat verder as 45km vanaf die radarstel is, insluit. Residu-stipping wys dat die afstand van die meter vanaf die radarstel as 'n afsonderlike onafhanklike veranderlike in die regressievergelyking ingesluit behoort te word, d.w.s. die beraming verbeter met logR = 3-0 + a,(logZ) + a2(afstand). Hierdie meervoudige regressiemodel stem ooreen met die teoretiese model van Smith en Krajewski omdat e -- afstand as 'n praktiese manifestasie van die foutproses [e.,, (ij)] beskou kan word. Omdat E(ez) = eE<ZJ e'"a' as Z 'n lognormaalverdeling het, kan die sydigheid wat ontstaan wanneer antilogaritmes geneem word, reggestel word deur die beraamde reenval met e112 "' te vermenigvuldig. Die studie !ewer 'n bydrae met die afleiding van 'n beramingstegniek wat die beraming van neerslag uit radar betekenisvol verbeter. / In a study of a rain-gauge network that was installed for a weather modification experiment in Bethlehem, South Africa, precipitation values R; observed at 43 gauging stations are compared to the observed radar reflectivity Z;. Although radar provides spatial and temporal measurements of reflectivity that are immediately available at one location, the accuracy of radar estimation of rainfall is uncertain due to various potential errors in the conversion from reflectivity to rainfall. Rain-gauges are assumed to give accurate point measurements of rainfall and there is general agreement that the combination of systems is better than either system alone. In this study I explore the application of the general linear model as an estimation technique. Previous studies have used the log-log transform, i.e. logZ = logA + b(logR) of the Z = ARb relation, and applied least-squares regression analysis to determine the coefficients A and b. This implicitly assumes that the disturbances are uncorrelated. Working with the inverse relation R = czd i.e. logR = logC + d(logZ) and assuming that the observations are not independent we compute the regression coefficients using generalised least squares. To model the spatial dependence of the rain-gauge observations we compute experimental variograms from the data and fit them with theoretical variograms which are then used to fill the variance-covariance matrix. "On average" this method performs better than ordinary regression for the analyses that included rain-gauges further than 45km from the radar set. Residual plotting revealed that distance of the rain-gauge from the radar set should be included as a separate independent variable in the regression equation, i.e. logR = ao + a1(logZ) + a1(distance) improved the estimation of rainfall as it performs better than ordinary regression. This multiple regression model agrees with the theoretical model of Smith and Krajewski in the sense that e "'distance is a practical manifestation of the error process [ e,, (ij)]. Showing that E( ez) = el!.(!.) e 112 "' if Z has a lognormal distribution, the bias when taking antilogs can be removed by multiplying estimated rainfall by e1 ' 2a'. The contribution of this study is the derivation of an estimation technique which significantly improves the estimation of rainfall from radar / Mathematical Sciences / D. Phil. (Statistics)

Natural disasters are increasing in frequency and intensity and have devastating impacts on individuals, both humanitarian and economic, particularly in developing countries. Microinsurance is seen as one promising instrument of disaster risk management, however the level of demand for respective projects remains low. Using behavioural games and a discrete choice experiment, this paper analyses the demand for hypothetical microinsurance products in rural Cambodia and contributes significant household level evidence to the current research. A general preference for microinsurance can be found, with demand significantly affected by price, provider, requirements for prevention and combinations with credit. Furthermore, financial literacy, risk aversion, levels of trust and previous disaster experience impact the individual demand for flood insurance in rural Cambodia.

Lighting accounts for nearly 20% of overall U.S. electricity consumption, 14% of U.S. residential electricity consumption, and 6% of total U.S. carbon dioxide equivalent (CO2e) emissions. A transition to alternative energy-efficient technologies could reduce this energy consumption considerably. We studied three questions related to energy efficiency lighting choices and consequences, which are: • Question 1: How large is the system-wide effect of a residential lighting retrofit with more efficient lighting technologies? • Question 2: Based on stated preference (SP) data, which factors influence consumer choices for general service light bulbs? What is the effect of the new lighting efficiency label mandated by the Federal Trade Commission? • Question 3: What can we learn about market trends and consumer choices from consumer panel data (i.e. revealed preference (RP) data) for general service light bulbs between 2004 and 2009? How can we compare the findings from SP and RP data, and which findings are robust across the two? In Chapter 2, we focus on the issue of lighting heat replacement effects. The issue is as follows: lighting efficiency goals have been emphasized in various U.S. energy efficiency policies. However, incandescent bulbs release up to 95% of input energy as heat, and it has been argued that replacing them with more efficient alternatives has a side effect in the overall building energy consumption: it increases the heating service that needs to be provided by the heating systems and decreases the cooling service that needs to be provided by the cooling systems. We investigate the net energy consumption, CO2e emissions, and saving in energy bills for single family detached houses across the U.S. as one moves towards more efficient lighting systems. In some regions, these heating and cooling effects from more efficient lighting can undermine up to 40% of originally intended primary energy savings, erode anticipated carbon savings completely, and lead to 30% less household monetary savings than intended. However, this overall effect is at most one percent of total emissions or energy consumption by a house. The size of the effect depends on various regional factors such as climate, electricity fuel mix, differences in emission factors of main energy sources used for heating and cooling, and electricity prices. Other tested factors such as building orientation, insulation level, occupancy scenario, or day length do not significantly affect the results. Then, in Chapter 3, we focus on factors that drive consumer choices for light bulbs. We collected stated preference data from a choice-based conjoint field experiment with 183 participants. We estimate discrete choice models from the data and find that politically liberal consumers have a stronger preference for compact fluorescent lighting technology and for low energy consumption. Greater willingness-to-pay for lower energy consumption and longer life is observed in conditions where estimated operating cost information was provided. Providing estimated annual cost information to consumers reduces their implicit discount rate by a factor of five, lowering barriers to adoption of energy efficient alternatives with higher up-front costs; however, even with cost information provided, consumers continue to use implicit discount rates of around 100%, which is larger than that estimated for other energy technologies. Finally, we complemented the stated preference study with a revealed preference study. This is because stated preference data alone have limitations in explaining consumer choices, as purchases are affected by many other factors that are outside of the experimenter control. We investigate consumer preferences for lighting technology based on revealed preference data between 2004 and 2009. We assess the trends in lighting sales for different lighting technologies across the country, and by store type. We find that, across the period between 2004 and 2009, sales of all general service light bulbs are almost monotonically decreasing, while CFL sales peaked in 2007. Thanks to increasing adoption of CFLs during the period, newly purchased light bulbs contributed to lowering carbon emissions and electricity consumption, while not sacrificing total produced lumens as much. We study consumer preferences for real light bulbs by estimating choice models, from which we estimate willingness-to-pay (WTP) for light bulb attributes (watt and type) and implicit discount rates (IDR) consumers adopt for their purchases. We find that the campaign for efficient bulbs in Wal-Mart in 2007 is potentially related to the peak in CFL adoption in 2007 in addition to the effects of the EISA or other factors/programs around the same period. Consumers are willing to pay, $1.84 more for a change from an incandescent bulb to a CFL and -$0.06 for 10W increase, the values which also include willingness-to-pays for corresponding changes in unobserved variables such as life and color. IDRs for four representative states range between around 230% and 330%, which is in a similar range we estimate from the choice experiment. Overall, even with energy efficiency labels, nationwide promotion of CFLs by retailers, or better availability of CFLs in the transforming residential lighting market, we see the barriers to energy efficient residential lighting are still persistent, which are reflected in high implicit discount rates observed from the models. While we can expect the EISA to be effective in lowering the barriers through regulation, it alone will not close energy efficiency gap in the residential lighting sector.