Aminohapete LC-MS analüüsiks kasutatavate derivatiseerivate reagentide iseloomustamine

Väitekirja elektrooniline versioon ei sisalda publikatsiooneAminohapped on valkude „ehituskivideks“, neil on oluline roll ainevahetuses ja seega ka haiguste diagnoosimisel ja toiduainetes. Seetõttu on olulised ka aminohapete madalad sisaldused, näiteks kaasasündinud ainevahetushäirete tuvastamisel vastsündinute verest. Madala sisaldusega ainete uurimiseks keerulistes proovides (nt aminohapped toiduainetes või veres) kasutatakse tänapäeval vedelikkromatograafia-massispektromeetria (LC-MS) meetodit, mis lahutab segud komponentideks (LC) ja tuvastab need (MS). LC-MS analüüsiks peavad analüüsitavad ained kromatograafiliselt lahutuma ja efektiivselt ioniseeruma. Selle saavutamiseks on mõnel juhul, sh aminohapete analüüsil, vaja ained keemiliselt muundada sobivasse vormi, mida nimetatakse derivatiseerimiseks. LC-MS analüüsi olulisimaks nõrkuseks on proovi muude komponentide poolt põhjustatud ebamäärasus analüüsitulemustes, mida nimetatakse maatriksiefektiks. Derivatiseerimisega LC-MS analüüsil esinevaid maatriksiefekte on vähe uuritud. Käesolevas töös uuriti maatriksiefekte, mis esinevad derivatiseeritud aminohapete LC-MS analüüsil. Selleks kasutati kolme meetodit, nelja juba kasutusel olevat ja kahte Tartu Ülikoolis väljatöötatud derivatiseerivat reagenti ning ühe rakendusena määrati 22 aminohappe sisaldused kaheksas kodumaises taimeekstraktis. Leiti, et erinevate derivatiseerivate reagentide korral on maatriksiefektid erinevad. Maatriksiefekte põhjustasid üldjuhul proovide teised komponendid, kuid mõnel juhul ka derivatiseerimisel kasutatud abistavad ained. Leiti, et tavalisest erineva MS ioonallika (APCI) ja detekteerimisrežiimi (negatiivsete ioonide ESI) kasutamine aminohapete derivaatide analüüsimiseks võimaldab märkimisväärselt vähendada maatriksiefekte. Töö tulemused võimaldavad konkreetse analüütilise probleemi lahendamiseks valida sobiva derivatiseeriva reagendi koos vastava detekteerimisrežiimiga. Samuti aitavad töö tulemused kaasa uudsete derivatiseerivate reagentide arendamisele ja disainileAmino acids are „building blocks“ of proteins, they have important role in metabolism and are therefore also important when diagnosing diseases and analyzing food. Even low concentrations of amino acids are important, e.g. diagnosing inherited metabolic disorders of newborn children. The most widely applied analytical method for low concentrations in complex matrices is the liquid chromatography mass spectrometry (LC-MS), which separates mixture into components (LC) and detects them (MS). LC-MS analysis requires that the analyzed components are separated chromatographically and are efficiently ionized. In order to achieve this in some cases, including for analysis of amino acids, the analyte is converted into a suitable form. The process is called derivatization. One of the main weaknesses of LC-MS analysis is the influence of other sample components on the analysis results, called matrix effects. The matrix effects of analyses involving derivatization have not been thoroughly investigated. The present work focused on the study of matrix effects which affect LC-MS analysis of derivatized amino acids. Matrix effects were investigated using three methods, six derivatization reagents (four previously used and two developed at the University of Tartu) and, as one application, the concentrations of 22 amino acids were determined in eight Estonian herbal extracts. The results showed that different derivatization reagents are affected differently by the matrix effects. Matrix effects are caused by other sample components or by reagents used for the derivatization reaction. The application of less common ionization source (APCI) and ion mode (negative ion mode ESI) for analysis of derivatized amino acids reduces matrix effects substantially. The results of this work enable to choose a suitable derivatization reagent with respective detection mode for a specific analytical problem. Moreover, the conclusions contribute to the development and design of novel derivatization reagent

Likelihood Geometry of Reflexive Polytopes

We study the problem of maximum likelihood (ML) estimation for statistical models defined by reflexive polytopes. Our focus is on the maximum likelihood degree of these models as an algebraic measure of complexity of the corresponding optimization problem. We compute the ML degrees of all 4319 classes of three-dimensional reflexive polytopes, and observe some surprising behavior in terms of the presence of gaps between ML degrees and degrees of the associated toric varieties. We interpret these drops in the context of discriminants and prove formulas for the ML degree for families of reflexive polytopes, including the hypercube and its dual, the cross polytope, in arbitrary dimension. In particular, we determine a family of embeddings for the $d$-cube that implies ML degree one. Finally, we discuss generalized constructions of families of reflexive polytopes in terms of their ML degrees.Comment: 30 pages, 6 figures, 5 table

European Antidumping Law and Procedure

This article is adapted from the presentations made by Messrs. Oldekop and Van Bael at the Symposium on Antidumping Law held at the University of Michigan Law School on November 3 and 4, 1978

RELACIONES ENTRE LA ARGENTINA Y LA COMUNIDAD ECONOMICA EUROPEA.

En españolEl tema central de la disertación a cargo del Sr. Embajador de la Comunidad Económica Europea en la Argentina fueron las Relaciones entre la Comunidad Económica Europea y la Argentina. Sin embargo, a modo de introducción, fueron contestados algunos interrogantes cuyas respuestas delinearon los Objetivos de la Comunidad Económica Europea, la situación actual del Comercio entre América Latina y la Comunidad (marcando las diferencias desfavorables para Latinoamérica respecto de décadas anteriores), la evaluación de los posibles beneficios para este continente con la perfección del Mercado Unico Europeo, y las Orientaciones de la Comunidad en sus Relaciones en América Latina. Una constante a lo largo de toda la disertación fue el hincapié realizado en el carácter Institucional de las relaciones de la Comunidad con América Latina, y especialmente con la Argentina. Así entonces, un importante lugar ocuparon las referencias a las vinculaciones de la Comunidad en el Grupo Río, la O.E.A., el SELA y el Mercosur, como así también el esfuerzo de la Comunidad en respaldar la democracia, la promoción de la justicia social y los derechos humanos en América Latina sobre la base de una Política de Cooperación. Finalmente, en lo que respecta a las relaciones con Argentina, se detallaron los tres hechos fundamentales que motivaron la positiva evolución de las relaciones con la C.E.E.: el restablecimiento de las relaciones de Argentina con Gran Bretaña, la conclusión del Acuerdo Marco entre la Comunidad y la Argentina y la apertura de una Delegación Permanente de la Comunidad en Buenos Aires. Para concluir fueron expuestos los aspectos más salientes del Acuerdo Marco de Cooperación firmado entre la Comunidad y la Argentina el 2 de Abril de 1990 en Luxemburgo, a través del cual se intentará la optimización en el intercambio comercial bilateral, la cooperación en materia pesquera, industrial y de servicios donde las inversiones productivas y el aliento a la pequeña y mediana empresa tienen un lugar de preferencia.En inglésThe German Ambassador reviewed the unification of Germany. He outlined its historical oportunity, and criticized some groups that had been too ductile towards East Germany, Meridional and Eastern Europe Communists Regimes. Those groups -though being a minority exerted an important political influence. He also remarked that national unification, which had been an essential objective of German foreign policy for 40 years, was achieved in a few months during 1990. The Embassador also pointed out the social, political and economic obligations wich were assumed by West Germany when the unification took place. West Germany will have in 1995 an internal debt 15% higher than in 1990. The productivity of East Germany compared to West Germany is only 30%. In addition to great unemployement there is the problem of the complete restructuring of the East German economic structure. On the other hand, Germany is moving towars a future World Order based on an "International Democratic Pax", peace would be garanteed by democracies -real democracies- due to their internal structures are practically uncapable of acts of aggression. Regarding the German international security, he underlined the importance of OTAN, OCDE and EC for his country and pointed out the interests of Germany in each organism. Finally, he stated that unified Germany in the United Nations (a future member of the Security Council); part of a regionalized Europe, with an impor-tant Democratic and Economical tradition and whith a moderate, balanced and cooperative foreing policy, moves away, the ghost of a "Germany too strong"

Сборник трудов, исполненных студентами при Метеорологической обсерватории имп. Юрьевского университета = Sammlung von Arbeiten, ausgeführt von Studenten am Meteorologischen Observatorium der kaiserlichen Universität zu Jurjew; Томь IV

Tekst vene, saksa ja prantsuse keeles.http://tartu.ester.ee/record=b1757754~S1*es

Die Anfänge der katholischen Kirche bei den Ostseefinnen : eine Untersuchung über die Formen der religiösen Expansion im Mittelalter

http://www.ester.ee/record=b3674442*es

Carbon, biodiversity, and livelihoods in forest commons: synergies, trade-offs, and implications for REDD+

Understanding the relationships and tradeoffs among management outcomes in forest commons has assumed new weight in the context of parallels between the objectives of community forest management and those of reduced emissions for deforestation and forest degradation (REDD+) programs to reduce carbon emissions while supporting local livelihoods. We examine the association between biophysical, demographic, institutional and socio-economic variables and three distinct forest management outcomes of interest to both community forestry and REDD+ advocates—carbon storage, biodiversity conservation, and livelihood benefits—in 56 forest commons in Nepal. REDD+ programs aim foremost to increase forest carbon storage and sequestration, but also seek to improve forest biodiversity, and to contribute to local livelihood benefits. The success of REDD+ programs can therefore be defined by improvements in one or more of these dimensions, while satisfying the principle of ‘do no harm’ in the others. We find that each outcome is associated with a different set of independent variables. This suggests that there is a need for policy-makers to clearly define their desired outcomes and to target their interventions accordingly. Our research points to the complex ways in which different factors relate to forest outcomes and has implications for the large number of cases where REDD+ projects are being implemented in the context of community forestry