Agricultural research and development (R&D) investment is becoming an increasingly important policy issue as food prices push upwards and food security problems emerge. An important source of agricultural R&D funding is from producer check-offs, which are increasingly being used to fund applied agricultural research such as disease management, genetic improvement, and weed control. Existing studies of producer-funded agricultural R&D indicate that there are high private and social rates of return to agricultural R&D investment by farmers, and thus that farmers are under investing in R&D. The focus of this thesis is at the producer level. This study examines one of the factors -- the horizon problem -- behind the apparent disincentive for farmers to invest in producer-funded R&D activities. It has been argued that given the long period of time over which the benefits of R&D investment occur, the increasing age of the farm population implies that the horizon problem could be indeed an important factor in producer underinvestment. Contrary to this widely acknowledged argument, this study shows the horizon problem is likely not a factor affecting farmers R&D investment decisions. Two models are developed to examine the horizon problem. The first model consists of a framework for determining the marginal internal rate of return of investing in R&D. Specifically, the model calculates the internal rate of return -- i.e., IRRh -- associated with the farmers' planning horizon and compares this to the internal rate of return -- i.e., IRR bar-- associated with the benefit horizon of the R&D. The impact of the horizon problem is determined by examining the difference between IRRh and IRR bar. The results of the horizon problem model show how that, contrary to what some authors have argued, the horizon problem is likely not a disincentive for R&D investment, unless the time horizon of farmers is very short. Given that the membership horizon for the average Canadian producer is 15 to 20 years, it is expected that the horizon problem is not an issue for Canadian producers. Furthermore, the analysis assumes farmers only are concerned with profit maximization. However, farmers may also consider other factors when making R&D investment decisions, such as future generations of agricultural producers and environment issues. The results of this study show that, even under the assumption of profit maximization, the horizon problem is not an issue for Canadian farmers, let alone in a more realistic model implemented by including factors other than profit. The results of the horizon problem model also show that the impact of the horizon problem is not affected by land tenure relationships. The second model consists of a multi-region, multi-product trade model that is used to examine the impact of Canadian pea R&D funding on consumers and producers in Canada and in various countries around the world that produce and consume pulses. To address the underinvestment issue, it is important to understand the question of who benefits from the research that is undertaken, and who bears the cost. Given that Canada is the largest pea exporter in the world an increase in R&D investment can be expected to have a significant impact on international trade and overseas producers and consumers. The simulation results from the second model illustrate that with increased pea R&D investment, Canadian producers, as well as consumers in all regions, are better off as a result of the R&D investment, while overseas producers are worse off. The results of the sensitivity analysis show that a pivotal supply shift associated with an increased levy, combined with a parallel supply curve shift due to increases in the knowledge stock, does affect the IRR in the large country versus the small country case. This result differs from the result that occurs when there is a parallel shift in supply at both the levy and R&D stages, indicating that it is important to understand the interaction between the manner in which R&D is funded, the way in which R&D affects supply and the trade status of a country. The results of the sensitivity analysis also indicate that the IRR to Canadian producers depends critically on how large an impact pea R&D has on the production of other crops (e.g., wheat and canola). The larger is this impact -- i.e., the more that wheat and canola production falls as a result of higher yields/lower costs of pea production -- the smaller is the IRR. The results also indicate that the elasticities of demand for peas and lentils in the importing countries do not have an impact on the IRR in the case where Canada is a large country exporter for peas only; however, they do have an impact on IRR in the case where Canada is a large exporter for both peas and lentils. In all cases, the more elastic is the demand, the higher is the IRR.

In April 2010, approximately 4.9 million barrels of oil were accidentally released into the Gulf of Mexico during the Deepwater Horizon Macondo Mc252 Oil Spill. Some of the surface oil was carried by prevailing winds and currents and reached the coast of Louisiana impacting marsh and marine ecosystems. One and a half years after this incident, a set of oiled marsh samples (2 grab samples) coupled with nearby subtidal and intertidal cores (12 cores) were collected from Barataria Bay, Louisiana to determine the probable source of petroleum residues present and to characterize the chemical composition of the oil. Plus, pre-spill core which was collected from Barataria Bay in 2007 was analyzed to identify the background hydrocarbon composition of the area. Polycyclic aromatic hydrocarbons (PAH), total petroleum hydrocarbons (TPH), biomarker, and stable carbon isotope compositions of selected samples were detected using a GC-MS and an elemental analyzer Conflo system coupled to a DeltaPlusXP isotope ratio mass spectrometer. The comprehensive chemical data allowed us to classify the pre and post-spill samples into 4 Groups. According to this classification, Group 1 and Group 2 samples had the highest concentrations of petroleum-derived hydrocarbons. Group 3 and background samples, on the other hand, was dominated by biogenic signatures. Although a direct connection between the detected and spilled Macondo oils results are complicated due to confounding factors (e.g., already present hydrocarbons and weathering processes), our biomarker data indicates that both oils have similar signatures. This close genetic relationship was also identified by stable carbon isotope analysis. The impact of the Macondo Mc252 Oil Spill in Barataria Bay appears to be limited to areas closer to the source. The oil has undergone moderate weathering and has penetrated into, the at least, the top 9 cm sediments. Additionally, to examine the decadal-scale history of sedimentation in these marshes, a sediment core was analyzed for the radioisotope 137Cs. The observed sedimentation rate of 0.39 cm/yr shows that oil pollutant input into Barataria Bay has been ongoing for at least 50-60 years.

Chemical vapor deposition (CVD) is an industrially important process to deposit crystalline and amorphous thin films on solid substrates. In situ sensing for CVD is necessary for process monitoring, fault detection, and process control. The challenge of in situ sensing lies in the prohibitive environment of the CVD process. Optical sensors such as the reflectometer and the ellipsometer are the most promising sensors because they can be installed outside of the deposition chamber, and are sensitive and easy to implement. However, the optical sensors do not measure film properties directly. Mathematical methods are needed to extract film properties from indirect optical measurements. Currently the most commonly used method is least squares fitting. In this project, we systematically investigated in situ reflectometry data interpretation based on state estimation theory. Optical models for light reflection on both smooth and rough surfaces were studied. The model validation results indicated that the effective medium model is better than the scalar scattering model when the surface is microscopically rough. The analysis of the observability for the sensor models indicated that the linearized observability does not always guarantee the true observability of a nonlinear system. We studied various state estimators such as batch least squares fitting (BLS), recursive least squares fitting (RLS), extended Kalman filter (EKF), and moving horizon estimation (MHE). It was shown that MHE is the general least-squares-based state estimation and BLS, RLS, and EKF are special cases of MHE. To reduce the computational requirement of MHE, a modified moving horizon estimator (mMHE) was developed which combines the advantage of the computational efficiency in RLS and the a priori estimate in MHE. State estimators were compared in simulated film growth processes, including both process model mismatch and sensor model mismatch, and reflection of both single wavelength and dual wavelength. In the case of process model mismatch and reflection on a smooth surface, there exists an optimum horizon size for both RLS and mMHE, although mMHE is less sensitive to the horizon size and performs better than RLS at all horizon sizes. The estimate with dual wavelength is more accurate than that with single wavelength indicating that estimation improves with more independent measurements. In the case of reflection on a rough surface, RLS failed to give a reasonable estimate due to the strong correlation between roughness and the extinction coefficient. However, mMHE successfully estimated the extinction coefficient and surface roughness by using the a priori estimate. MHE is much more computationally intensive than mMHE and there is no significant improvement on the estimation results. In the case of sensor model mismatch, either state estimator gave a good result, although mMHE consistently gave a better estimate, especially at a shorter horizon size. In order to test the state estimators in a real world environment, we built a cold-wall low-pressure chemical vapor deposition testbed with an in situ emissivity-correcting pyrometer. Fully automatic data-acquisition and instrument-control software was developed for the CVD testbed using LabVIEW. State estimators were compared using two experimental reflectance data sets acquired under different deposition conditions. The estimated film properties are compared with ex situ ellipsometry and AFM characterization results. In all cases, mMHE consistently yielded better estimates for processes under quite different deposition conditions. This indicated that mMHE is a useful and robust state estimator for in situ sensor data interpretation. By using the information from both the process and the sensor model, one can obtain a better estimate. A good feature of mMHE is that it provides such a versatile framework to organize all these useful information and gives a user the opportunity to interact with fitting and make wise decisions in the in situ sensor data interpretation.

Covariance assignment theory, introduced in the late 1980s, provided the only means to directly control the steady-state error properties of a linear system subject to Gaussian white noise and parameter uncertainty. This theory, however, does not extend to control of the transient uncertainties and to date there exist no practical engineering solutions to the problem of directly and optimally controlling the uncertainty in a linear system from one Gaussian distribution to another. In this thesis I design a dual-mode Receding Horizon Controller (RHC) that takes a controllable, deterministic linear system from an arbitrary initial covariance to near a desired stationary covariance in finite time. The RHC solves a sequence of free-time Optimal Control Problems (OCP) that directly controls the fundamental solution matrices of the linear system; each problem is a right-invariant OCP on the matrix Lie group GLn of invertible matrices. A terminal constraint ensures that each OCP takes the system to the desired covariance. I show that, by reducing the Hamiltonian system of each OCP from T?GLn to gln? x GLn, the transversality condition corresponding to the terminal constraint simplifies the two-point Boundary Value Problem (BVP) to a single unknown in the initial or final value of the costate in gln?. These results are applied in the design of a dual-mode RHC. The first mode repeatedly solves the OCPs until the optimal time for the system to reach the de- sired covariance is less than the RHC update time. This triggers the second mode, which applies covariance assignment theory to stabilize the system near the desired covariance. The dual-mode controller is illustrated on a planar system. The BVPs are solved using an indirect shooting method that numerically integrates the fundamental solutions on R4 using an adaptive Runge-Kutta method. I contend that extension of the results of this thesis to higher-dimensional systems using either in- direct or direct methods will require numerical integrators that account for the Lie group structure. I conclude with some remarks on the possible extension of a classic result called Lie?s method of reduction to receding horizon control.

This exploratory and descriptive study provides an increased understanding of the topics being explored in both published research and industry reporting in the field of educational technology. Although literature in the field is plentiful, the task of synthesizing the information for practical use is a massive undertaking. Latent semantic analysis was used to review journal abstracts from ten highly respected journals and the New Media Consortium Horizon Reports to identify trends within the publications. As part of the analysis, 25 topics and technologies were identified in the combined corpus of academic journals and Horizon Reports. The journals tended to focus on pedagogical issues whereas the Horizon Reports tended to focus on technological aspects in education. In addition to differences between publication types, trends over time are also described. Findings may assist researchers, practitioners, administrators, and policy makers with decision-making in their respective educational areas.

Thesis (M.S. in Applied Physics)--Naval Postgraduate School, June 2005. / Thesis Advisor(s): Richard M. Harkins, Gamani Karunasiri. Includes bibliographical references (p. 77-78). Also available online.

Thesis (MScEng)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: A different approach of employing attitude sensors with incomplete measurements in an attitude determination system is investigated. The amount of available attitude sensors on small satellites are limited, and the failure of sensors can be fatal when accurate attitude determination is necessary. The problem with sensors with incomplete measurements is that they must be used in combination with other sensors to obtain three dimensional attitude information. The aim is to enhance the possible number of sensor combinations that can be employed, in an attempt to improve the ability of the attitude determination system to tolerate sensor failures. An alternative sensor structure consisting of a magnetometer and two horizon sensors is presented. A method to obtain vector observations of the attitude from a combination between magnetometer and horizon sensor measurements is derived and tested. A full state Extended Kalman Filter is used to determine the satellite's attitude, attitude rate and disturbance torque from these vector observations. A second Extended Kalman Filter structure, using only magnetometer measurements, is implemented. The magnetometer Extended Kalman Filter and the horizon/magnetometer Extended Kalman Filter are integrated to obtain a single Extended Kalman Filter structure to determine the satellite's full attitude state. Integration is done by switching between the different pairs of vector information. A systematic analysis of the integrated filter's dynamic behaviour during the switching stages is done by means of a series of case studies. / AFRIKAANSE OPSOMMING: Die gebruik van oriëntasiesensore met onvolledige metingsdata in oriëntasiebepalingsstelsels is ondersoek. Slegs 'n beperkte aantal oriëntasiesensore is beskikbaar op mikro satelliete. 'n Foutiewe sensor kan dus noodlottig wees wanneer akkurate oriëntasiebepaling nodig is. Die probleem met sensore met onvolledige metingsdata is dat dit in sensor kombinasies gebruik moet word om drie dimensionele oriëntasieinligting te verkry. Die doel is dus om die moontlike aantal sensor kombinasies sodanig te vermeerder dat die oriëntasiebepalingsstelsel beter bestand sal wees teen moontlike sensor falings. 'n Alternatiewe sensor struktuur, bestaande uit 'n magnetometer en twee horison sensore, is ondersoek. 'n Metode vir die verkryging van 3-as oriëntasie inligting vanaf 'n kombinasie van magnetometer en horison sensor metingsdata is afgelei en getoets. 'n Vol toestand uitgebreide Kalmanfilter is gebruik om the satelliet se oriëntasie, oriëntasie snelheid en versteurings draairnoment vanaf die vektor observasies af te lei. 'n Tweede uitgebreide Kalmanfilter struktuur, wat slegs magnetometer metingsdata gebruik, is geïmplementeer. Die magnetometer filter en die horison/magnetometer filter is geïntegreer sodat een uitgebreide Kalmanfilter struktuur volle oriëntasie inligting kan aflei vanaf verskillende pare vektors met oriëntasie inligting. Integrasie is gedoen deur te skakel tussen die verskillende vektorpare. 'n Sistematiese analise van die geïntegreerde filter se dinamiese gedrag gedurende die oorskakelingstye is gedoen deur middel van 'n reeks gevallestudies.

The Templo Viejo at Pachacamac: New Contributions to the Study of the Middle HorizonThe Old Temple of Pachacamac is one of the Lima culture compounds within the Pachacamac Sanctuary complex. Research by the authors between 1986 and 1989 revealed various architectural construction phases. Two Middle Horizon phases were recognized modifying older, Early Intermediate Period structures constructed from millions of tiny sun-died adobe bricks. A series of intrusive offerings is related to intense rainfall events / El Templo Viejo de Pachacamac es uno de los complejos lima que posee el Santuario de Pachacamac. Las investigaciones de los autores entre 1986 a 1989 revelaron varias fases constructivas. Para el Horizonte Medio se detectaron dos fases de ocupación que modifican las estructuras del Periodo Intermedio Temprano del edificio hecho de millones de adobitos. Una serie de ofrendas intrusivas se relacionan también con fuertes eventos de lluvia.

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Extending Schreiber’s mosaic model, we construct a political economy model for how the Wari Empire could have functioned based on available evidence. We argue that Wari administrators sought to create a broadly integrating interregional system without the benefit of markets through the creation of a staple-based mobilization of agricultural production in order to support state-managed ceremonies, corvée labor for construction projects, a warrior class, and craft and ritual specialists. The success ofthis staple-based mobilization, likely a precedent for the Inca imperial economy, was limited because it was a novel experiment in statecraft in a world of marked regionalism. Yet top-down wealth finance and bottom-up globalization managed to further integrate outlying regions by fueling the specialized production of high-end, symbolically charged goods that materialized apopular religious ideology that had coalesced at Huari. Although wealth finance and globalization are often seen as alternative explanations for Middle Horizon dynamics, we argue that they represent complementary, and often linked, strategies pursued by Wari bureaucrats, local leaders, and craftspeople to profit off of the surging interregional interactions of the period. Nothing like Wari had existed previously in the Andes — it was the creation of a state struggling, and ultimately failing, to project itself overa vast region. / Extendiendo el modelo del mosaico de Schreiber, se construye un modelo económico para la manera de como el Imperio wari pudo haber funcionado en base a la evidencia obtenida. Sostenemos que los administradores wari procuraban crear un amplio sistema de integración interregional sin el beneficio de mercados, a través de la creación de una movilización de producción agrícola, queestuviera basada en productos de primera necesidad para poder apoyar las ceremonias gestionadas por el Estado, la labor corvéepara proyectos de construcción, una clase guerrera, y especialistas en artesanías y rituales. El éxito de esta movilización basada en productos de primera necesidad, que probablemente fue un antecesor a la economía del Imperio inca, fue limitado por serun experimento nuevo en la política de un mundo de marcado regionalismo. Aun así, las declinantes riquezas y la ascendiente globalización ayudaron a integrar más aún a las regiones periféricas, incrementando la producción especializada de bienes de lujo cargados de simbología, que materializaron una ideología popular religiosa que se unió en Huari. Aunque la economía de bienes de riqueza y la globalización son vistas con frecuencia como explicaciones alternativas para las dinámicas del Horizonte Medio, sostenemos que representan estrategias complementarias y, con frecuencia, vinculadas seguidas por burócratas wari, líderes locales, y artesanos para sacar provecho de las interacciones interregionales que surgían durante esta era. No ha existido otro grupo igual a los wari anteriormente en los Andes —fueron la creación de un Estado que luchó, y al final falló en su proyección sobre una amplia región —.