Estimation of covariance matrix and its inverse is of great importance in multivariate statistics with broad applications such as dimension reduction, portfolio optimization, linear discriminant analysis and gene expression analysis. However, accurate estimation of covariance or inverse covariance matrices is challenging due to the positive definiteness constraint and large number of parameters, especially in the high-dimensional cases. In this thesis, I develop several approaches for estimating large covariance and inverse covariance matrices with different applications. In Chapter 2, I consider an estimation of time-varying covariance matrices in the analysis of multivariate financial data. An order-invariant Cholesky-log-GARCH model is developed for estimating the time-varying covariance matrices based on the modified Cholesky decomposition. This decomposition provides a statistically interpretable parametrization of the covariance matrix. The key idea of the proposed model is to consider an ensemble estimation of covariance matrix based on the multiple permutations of variables. Chapter 3 investigates the sparse estimation of inverse covariance matrix for the highdimensional data. This problem has attracted wide attention, since zero entries in the inverse covariance matrix imply the conditional independence among variables. I propose an orderinvariant sparse estimator based on the modified Cholesky decomposition. The proposed estimator is obtained by assembling a set of estimates from the multiple permutations of variables. Hard thresholding is imposed on the ensemble Cholesky factor to encourage the sparsity in the estimated inverse covariance matrix. The proposed method is able to catch the correct sparse structure of the inverse covariance matrix. Chapter 4 focuses on the sparse estimation of large covariance matrix. Traditional estimation approach is known to perform poorly in the high dimensions. I propose a positive-definite estimator for the covariance matrix using the modified Cholesky decomposition. Such a decomposition provides a exibility to obtain a set of covariance matrix estimates. The proposed method considers an ensemble estimator as the center" of these available estimates with respect to Frobenius norm. The proposed estimator is not only guaranteed to be positive definite, but also able to catch the underlying sparse structure of the true matrix. / Ph. D.

The new modeling method presented here is classified as a substructure synthesis (SS) technique. The distinction between the new SS method and the component mode synthesis formulation is that no transformation between local coordinates and generalized coordinates occurs in the new SS method. The advantage of this is a retention of physical insight into the model and the ability to form equations of motions directly with generalized coordinates. The new formulation differs from other substructure synthesis formulation because it satisfies geometric, natural, displacement and force constraints between substructures into one mathematical process, instead of using both kinematic chains and boundary condition approximation methods. This has the advantage of reducing the complexity of the integrals that are required in the computation. The new formulation also results in global eigenfunction approximations and global generalized coordinates, which eventually satisfies the inclusion principle which means eigenvalue estimates converge from above their actual values. The analysis method also facilitates the examination of boundary conditions in a unique manner. The method is unique because constraints are explicitly examined and selectively satisfied. This allows the identification of extraneous constraints and provides guidance in the selection of admissible functions. The new SS formulation may be divided into two steps. The first step is to satisfy geometric boundary conditions of substructures with appropriate admissible functions. The second step is the modification of these admissible functions to minimally satisfy geometric constraints imposed by the interaction of substructures. Natural constraints can also be satisfied to improve convergence to the exact eigenvalues. The MAF-SS formulation results in explicit knowledge of the constraints coupling substructures. Changing these constraints with active feedback results in a modified structure. The effect of active feedback of terms proportional to the coupling constraints is to lower the stiffness of the structure. This increases the isolation between substructures. The ability to improve isolation using this unique type of feedback is demonstrated. The concept of structural modification through substructure constraint alteration 1s applied to systems using a multivariable feedback method. This is accomplished by combing the MAF-SS method with a standard eigenstructure assignment technique. This method uses the MAF-SS formulation to define a system with substructure constraint eigenstructure properties, the active feedback gain that realizes these systems is calculated with an eigenstructure assignment method. The MAF-SS has application to active control formulation, the result of this control can be an improvement in substructure isolation. / Ph. D.

(please take a look at the pdf)

Nos últimos anos, a irradiação por micro-ondas tem sido cada vez mais usada na síntese de varias moléculas orgânicas, devido a uma série de vantagens que essa nova tecnologia apresenta. Até o momento, existem poucos estudos sobre polimerizações assistidas por micro-ondas e menos ainda sobre a modificação de polímeros usando essa nova fonte de energia. Polímeros heterocíclicos contendo anéis azóicos, como o tetrazol possuem interesse acadêmico e comercial devido as suas várias aplicações. Nesta Dissertação foi estuda a modificação química da poliacrilonitrila pela incorporação em sua cadeia polimérica de 10% de grupos tetrazol empregando-se a irradiação de micro-ondas e o método convencional (térmico). Foram utilizados um forno de micro-ondas doméstico e um reator de micro-ondas monomodo nas reações assistidas por micro-ondas. As reações em reator foram realizadas em vaso aberto, em solução (DMF) ou em massa, sendo variado o tempo e a temperatura reacional, bem como a potência do equipamento. Os copolímeros produzidos foram caracterizados por espectroscopia na região do infravermelho (FTIR) e os teores de grupos tetrazol incorporados na PAN foram determinados por titulometria de neutralização. A poliacrilonitrila foi modificada quimicamente com sucesso tanto no forno doméstico quanto no reator de micro-ondas, como foi verificado pela sua análise de FTIR. Pela determinação do grau de incorporação de grupos tetrazol nos polímeros concluiu-se que, para a reação em solução, nas temperaturas mais elevas, bem como em uma potência maior, o teor de heterocíclico incorporado no polímero está muito próximo do valor obtido pelo método convencional. Já as reações conduzidas em massa apresentaram graus de incorporação inferiores as das feitas em solução. / In recent years, microwave irradiation has been increasingly used in the synthesis of various organic molecules, due to a number of advantages that this technology presents. To date, few studies on polymerization assisted by microwave and even less about the modification of polymers using this new source of energy. Polymers containing heterocyclic ring azoles such as tetrazole have academic and commercial interest due to their various applications. This thesis has been studying the chemical modification of polyacrylonitrile by its incorporation into the polymer chain, 10% of tetrazole groups employing the irradiation of microwave and conventional method (thermal). We used a domestic microwave oven and a reactor monomode microwave to assisted reactions in the microwave. The reactions were performed in reactor open cup in solution (DMF) or in bulk, and varied the reaction time and temperature, and power equipment. The copolymers were characterized by infrared spectroscopy (FTIR) and the concentrations of tetrazole groups incorporated into the PAN were determined by neutralization titration. The polyacrylonitrile was chemically modified with success both at home and in the oven microwave reactor, as verified by his analysis of FTIR. By determining the degree of incorporation of tetrazole groups in the polymers it was concluded that, for the reaction in solution at higher temperatures, as well as a higher power, the content of heterocyclic incorporated into the polymer is very close to the value obtained by the conventional method. The reactions were conducted in mass lower degree of incorporation of the solution made.

Which tensor fields G on a smooth manifold M can serve as a spacetime structure? In the first part of this thesis, it is found that only a severely restricted class of tensor fields can provide classical spacetime geometries, namely those that can carry predictive, interpretable and quantizable matter dynamics. The obvious dependence of this characterization of admissible tensorial spacetime geometries on specific matter is not a weakness, but rather presents an insight: it was Maxwell theory that justified Einstein to promote Lorentzian manifolds to the status of a spacetime geometry. Any matter that does not mimick the structure of Maxwell theory, will force us to choose another geometry on which the matter dynamics of interest are predictive, interpretable and quantizable. These three physical conditions on matter impose three corresponding algebraic conditions on the totally symmetric contravariant coefficient tensor field P that determines the principal symbol of the matter field equations in terms of the geometric tensor G: the tensor field P must be hyperbolic, time-orientable and energy-distinguishing. Remarkably, these physically necessary conditions on the geometry are mathematically already sufficient to realize all kinematical constructions familiar from Lorentzian geometry, for precisely the same structural reasons. This we were able to show employing a subtle interplay of convex analysis, the theory of partial differential equations and real algebraic geometry. In the second part of this thesis, we then explore general properties of any hyperbolic, time-orientable and energy-distinguishing tensorial geometry. Physically most important are the construction of freely falling non-rotating laboratories, the appearance of admissible modified dispersion relations to particular observers, and the identification of a mechanism that explains why massive particles that are faster than some massless particles can radiate off energy until they are slower than all massless particles in any hyperbolic, time-orientable and energy-distinguishing geometry. In the third part of the thesis, we explore how tensorial spacetime geometries fare when one wants to quantize particles and fields on them. This study is motivated, in part, in order to provide the tools to calculate the rate at which superluminal particles radiate off energy to become infraluminal, as explained above. Remarkably, it is again the three geometric conditions of hyperbolicity, time-orientability and energy-distinguishability that allow the quantization of general linear electrodynamics on an area metric spacetime and the quantization of massive point particles obeying any admissible dispersion relation. We explore the issue of field equations of all possible derivative order in rather systematic fashion, and prove a practically most useful theorem that determines Dirac algebras allowing the reduction of derivative orders. The final part of the thesis presents the sketch of a truly remarkable result that was obtained building on the work of the present thesis. Particularly based on the subtle duality maps between momenta and velocities in general tensorial spacetimes, it could be shown that gravitational dynamics for hyperbolic, time-orientable and energy distinguishable geometries need not be postulated, but the formidable physical problem of their construction can be reduced to a mere mathematical task: the solution of a system of homogeneous linear partial differential equations. This far-reaching physical result on modified gravity theories is a direct, but difficult to derive, outcome of the findings in the present thesis. Throughout the thesis, the abstract theory is illustrated through instructive examples. / Welche Tensorfelder G auf einer glatten Mannigfaltigkeit M können eine Raumzeit-Geometrie beschreiben? Im ersten Teil dieser Dissertation wird es gezeigt, dass nur stark eingeschränkte Klassen von Tensorfeldern eine Raumzeit-Geometrie darstellen können, nämlich Tensorfelder, die eine prädiktive, interpretierbare und quantisierbare Dynamik für Materiefelder ermöglichen. Die offensichtliche Abhängigkeit dieser Charakterisierung erlaubter tensorieller Raumzeiten von einer spezifischen Materiefelder-Dynamik ist keine Schwäche der Theorie, sondern ist letztlich genau das Prinzip, das die üblicherweise betrachteten Lorentzschen Mannigfaltigkeiten auszeichnet: diese stellen die metrische Geometrie dar, welche die Maxwellsche Elektrodynamik prädiktiv, interpretierbar und quantisierbar macht. Materiefeld-Dynamiken, welche die kausale Struktur von Maxwell-Elektrodynamik nicht respektieren, zwingen uns, eine andere Geometrie auszuwählen, auf der die Materiefelder-Dynamik aber immer noch prädiktiv, interpretierbar und quantisierbar sein muss. Diesen drei Voraussetzungen an die Materie entsprechen drei algebraische Voraussetzungen an das total symmetrische kontravariante Tensorfeld P, welches das Prinzipalpolynom der Materiefeldgleichungen (ausgedrückt durch das grundlegende Tensorfeld G) bestimmt: das Tensorfeld P muss hyperbolisch, zeitorientierbar und energie-differenzierend sein. Diese drei notwendigen Bedingungen an die Geometrie genügen, um alle aus der Lorentzschen Geometrie bekannten kinematischen Konstruktionen zu realisieren. Dies zeigen wir im ersten Teil der vorliegenden Arbeit unter Verwendung eines teilweise recht subtilen Wechselspiels zwischen konvexer Analysis, der Theorie partieller Differentialgleichungen und reeller algebraischer Geometrie. Im zweiten Teil dieser Dissertation erforschen wir allgemeine Eigenschaften aller solcher hyperbolischen, zeit-orientierbaren und energie-differenzierenden Geometrien. Physikalisch wichtig sind der Aufbau von frei fallenden und nicht rotierenden Laboratorien, das Auftreten modifizierter Energie-Impuls-Beziehungen und die Identifizierung eines Mechanismus, der erklärt, warum massive Teilchen, die sich schneller als einige masselosse Teilchen bewegen, Energie abstrahlen können, aber nur bis sie sich langsamer als alle masselossen Teilchen bewegen. Im dritten Teil der Dissertation ergründen wir die Quantisierung von Teilchen und Feldern auf tensoriellen Raumzeit-Geometrien, die die obigen physikalischen Bedingungen erfüllen. Eine wichtige Motivation dieser Untersuchung ist es, Techniken zur Berechnung der Zerfallsrate von Teilchen zu berechnen, die sich schneller als langsame masselose Teilchen bewegen. Wir finden, dass es wiederum die drei zuvor im klassischen Kontext identifizierten Voraussetzungen (der Hyperbolizität, Zeit-Orientierbarkeit und Energie-Differenzierbarkeit) sind, welche die Quantisierung allgemeiner linearer Elektrodynamik auf einer flächenmetrischen Raumzeit und die Quantizierung massiver Teilchen, die eine physikalische Energie-Impuls-Beziehung respektieren, erlauben. Wir erkunden auch systematisch, wie man Feldgleichungen aller Ableitungsordnungen generieren kann und beweisen einen Satz, der verallgemeinerte Dirac-Algebren bestimmt und die damit Reduzierung des Ableitungsgrades einer physikalischen Materiefeldgleichung ermöglicht. Der letzte Teil der vorliegenden Schrift skizziert ein bemerkenswertes Ergebnis, das mit den in dieser Dissertation dargestellten Techniken erzielt wurde. Insbesondere aufgrund der hier identifizierten dualen Abbildungen zwischen Teilchenimpulsen und -geschwindigkeiten auf allgemeinen tensoriellen Raumzeiten war es möglich zu zeigen, dass man die Gravitationsdynamik für hyperbolische, zeit-orientierbare und energie-differenzierende Geometrien nicht postulieren muss, sondern dass sich das Problem ihrer Konstruktion auf eine rein mathematische Aufgabe reduziert: die Lösung eines homogenen linearen Differentialgleichungssystems. Dieses weitreichende Ergebnis über modifizierte Gravitationstheorien ist eine direkte (aber schwer herzuleitende) Folgerung der Forschungsergebnisse dieser Dissertation. Die abstrakte Theorie dieser Doktorarbeit wird durch mehrere instruktive Beispiele illustriert.

Rural areas of New Mexico still exhibit post-colonial political patterns. In terms of its agricultural profile, subsistence farming has only recently (in the past generation) begun to give way to highly specialized, big-business farming interests. Older Hispanic and Pueblo communities struggle to maintain their farming traditions in the face of external economic factors. Now, with the increasing use of genetically-modified seeds on major farm operations and the ongoing development of a transgenic chile seed, a heritage crop, these populations are grappling with intellectual property issues and ecological implications that technological manipulation of native seeds bring. Other growers across the state also have serious concerns about their ability to grow crops from non-genetically modified seeds, as consumers have shown a preference for organic, non-genetically modified foods. Using the guiding analytical tools of Latour and Callon's Actor Network Theory (ANT), I assess the dynamics of power and influence among all agricultural stakeholders to find how a network of disparate elements can achieve “compromise among materially diverse elements” (Rutland and Aylett 2008). This work outlines a framework based on deliberative democratic principles to begin a participatory process that builds upon the disconnected agricultural network of New Mexico. A deliberative process enfranchises previously neglected stakeholders to develop an agricultural policy that deals with genetically engineered crops in a way that reflects the values and goals of the public. / text

Neatsiejama genetiškai modifikuotų organizmų (GMO) bei iš jų pagamintų produktų (GMP) teisinio reguliavimo dalis yra mokslas bei politika. –iame darbe analizuojamas GMO (GMP) teisinio reguliavimo raida ES ir Lietuvos Respublikoje. Nagrinėjamos tokios GMO ir GMP teisinio reguliavimo problemos, kaip etikos nuostatų suderinimas su žmogaus genų naudojimu kuriant maistui skirtus produktus; ES institucijų ir valstybių narių pozicijų išsikyrimas siekiant uždrausti apgalvotą GMO išleidimą į aplinką; visuomenės dalyvavimo priimant sprendimus dėl GMO (GMP) problematika ES ir Lietuvos Respublikoje – visuomenės „motyvuotos nuomonės“ instituto neefektyvumas. Taip pat analizuojamos ES teisės nuostatų dėl sankcijų nustatymo už GMO (GMP) reguliuojančių teisės aktų pažeidimus įgyvendinimo Lietuvos Respublikoje problemos t.y. nacionalinėje teisėje nenustačius atsakomybės pagrindiniams su GMO (GMP) veikla susijusiems juridiniams asmenims, praktiškai išlieka jų nebaudžiamumas; tai pat pažymėtina, kad teisės aktų, reglamentuojančių GMO ir GMP naudojimą, reikalavimų pažeidimai yra pakankamai skirtingo pobūdžio, o ATPK jie išvardinti viename straipsnyje, kartu numatyta gana didelis skiriamos baudos mažiausias dydis, - visa tai praktikoje sąlygoja nuobaudų neskyrimą bei neužtikrina Direktyvoje 2001/18/EB įtvirtintos sankcijos veiksmingumo, proporcingumo ir atgrasumo. Darbe nagrinėjamos tarptautinių sutarčių - Biologinės įvairovės ir Orhuso konvencijų - nuostatos dėl GMO bei jų įtaka ES ir Lietuvos... [toliau žr. visą tekstą] / Science and politics are part and parcel of law regulation of genetically modified organisms (GMO) and products (GMP) made from them. This work analyses development of law regulation of GMO (GMP) in ES and Lithuanian Republic. Such problems as ethical attitude towards usage of human genes in food production, distinction of ES isntitutions and member states according to their position, in purpose to forbid deliberate release of GMO into environment, problems of society involvment in taking decisions about GMO (GMP) in ES and Lithuanian Republic, inefficiency of public institute of "motivated opinion" (public comments) are disscussed in this work. Such topics as realisation of ES rules for definition of sanctions for breaking laws of GMO (GMP) usage in Lithuania Republic and rules of international contracts, such as Cartagena protocol on biosafety to the convention on biological diversity and Orhus convention, and their influence upon law regulation in ES and Lithuanian Republic are also disscussed here.

During the past decade, there has been growing public attention and concern over consuming products containing or processed with genetically modified organisms (GMOs). Labeling of the food products derived from the use of GMOs has thereby been a contentious debate across the world. Currently, there are two systems with regard to labeling GMO-based products: mandatory versus voluntary. The purpose of this study was to survey the research on GMOs, its application in agriculture and the surrounding labeling issues. A theoretical model was developed to analyze non-GMO producers' labeling decisions under a voluntary labeling regime, aimed at providing a theoretical perspective for governments that are contemplating the adoption of a voluntary approach to regulate GMO food products. The analysis indicates that the size of labeling costs and consumers' preferences toward non-GMO products are critical factors that will impact on non-GMO producers' labeling decisions.

In recent years, foods produced by genetic engineering technology have been on the world food market. The biosafety aspects, regulations, and labelling of these foods are still contentious issues in most countries. It is necessary to have approval for the use of GMOs in the production of food. Thus, detection and quantification of GMOs play crucial role for developing regulations on GM foods. In this study, raw and processed maize samples were analysed for genetic modification using a DNA based detection method, the Polymerase Chain Reaction. Ten raw food and 18 processed maize food including maize flour, starch, corn flakes, maize chips were collected from different markets located in different places in Turkey. The samples were examined for the presence of genetic elements located in the majority of transgenic crops such as NOS terminator, CaMV 35S promoter, kanamycin resistance (KanR) gene, using conventional PCR with oligonucleotide sets targeting to novel genes. Furthermore screening was conducted via Real-Time PCR assay for NOS terminator and 35S promoter. For confirming the presence of Bt11 maize lines event specific primers were utilised. Quantification of Bt11 maize lines were performed via Real-Time PCR. The result indicates that foreign genetic elements were found in all analysed raw material. In six out of 10 raw material, presence of Bt11 gene were identified. GMO detection was also possible for maize flour and starch, however in processed material as corn starch, corn flakes, corn chips and pop corn, transgenes were not detected.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2007. / Title from title screen (site viewed Oct. 10, 2007). PDF text: xv, 325 p. : ill. UMI publication number: AAT 3258775. Includes bibliographical references. Also available in microfilm and microfiche formats.