Esta tesis es de carácter interdisciplinario, entre economía y ciencias políticas. Usando métodos bien explotados en economía explico como las instituciones electorales afectan las decisiones de los individuos en varios contextos políticos. El capítulo 2 es normativo y propone dos modificaciones en los sistemas electorales. Ambos resultan en una participación más alta y dan incentivos a los partidos políticos a que sean de mejor calidad. Primero, analizo un sistema electoral donde el número de los candidatos que obtienen representación en el parlamento es endógeno y depende del nivel de la participación. Segundo, analizo el efecto de un quorum de participación en elecciones parlamentarias. Según mis resultados, las dos modificaciones implican beneficios más bajos para los partidos, y bienestar más alto para los ciudadanos. Dichos resultados explican porqué los partidos usan otros tipos de medidas para incrementar la participación en las elecciones. Además, mis resultados explican la evolución del uso de un quorum en algunos países. El capítulo 3 es un trabajo junto con Sabine Flamand. Estudiamos el efecto de un quorum de participación en reuniones de pocos miembros. Usando un modelo de reuniones repetitivas, demostramos que la decisión se retrasa cuando el quorum es alto, y que los miembros no pierden utilidad por el hecho de retrasar la decisión. Finalmente, la presencia de un quorum puede tanto aumentar como reducir el número de miembros tomando la decisión final. El capítulo 4 ofrece un análisis empírico de las decisiones de votar en blanco y votar nulo. El análisis es innovador porque por primera vez se tratan las dos decisiones por separado. Demuestro que el voto blanco contiene un mensaje de insatisfacción contra los partidos políticos, mientras que el voto nulo contiene insatisfacción contra las instituciones y los niveles de democracia. / The present thesis lies at the intersection of economics and political science. Using methods, well developed in economics, I try to understand how electoral institutions shape individuals' behavior in different political contexts. Chapter 2 has a normative flavor. Focusing on the interplay between low quality parties and citizens' apathy, I try to break the vicious cycle that links the two, by proposing two electoral rules that increase turnout in PR elections, and at the same time give incentives to parties to be of better quality. First, I propose an electoral rule where the number of candidates elected depends on the level of participation. Second, I propose the introduction of a participation quorum that has to be met in order for the election to be valid. The common feature and innovation of these rules is that turnout affects the electoral outcome, and as a consequence these rules incentivize parties to care about the level of turnout. I show that both rules, while they increase turnout they imply lower profits for parties. My results explain why parties target to increase turnout through a certain type of measures that do not necessary improve the quality of the vote. Moreover, I also explain the evolution of the use of the participation quorum in certain countries. Chapter 3 is coauthored with Sabine Flamand, and tries to understand the effect of such a participation requirement on individuals' behavior and the decision outcome. To this end, we model a setup of repeated meetings, where a small group of individuals has to take a decision. We show that the decision is delayed when the quorum requirement is high and members are not harmed by postponing the decision. Surprisingly, the presence of the quorum may decrease the number of attendees taking the decision, while we show that in order to avoid policy distortions, the required number of participants must be even. Apart from abstaining, voters that are not willing to support any of the candidates in most parliamentary elections, are given the choice to participate in the election and cast a blank or a null vote. A blank vote is a disapproval vote of all competing candidates, while a null vote is a vote cast erroneously or deliberately in a way not conforming with the legal voting procedure. Political scientists were treating blank and null votes in an identical way. My attempt in chapter 4 is to study these two protest actions on a separate basis, in order to understand, why in some elections blank votes are many more than null votes and vice versa. After constructing a database considering the percentages of blank and null votes separately, I show that the amount of blank and null votes cast in an election are not affected by the same factors. Null votes convey dissatisfaction towards the electoral and democratic institutions, while blank votes convey dissatisfaction towards the parties. More important, my results go against one of the prevailing criticisms of compulsory voting. The latter has no significant effect on the amount of uninformative votes since it has no significant effect on the amount of null votes. On the contrary, it increases only the amount of blank votes, which by definition disclose information, and in particular voters' disapproval of all competing parties. Although abstention is one of the most studied issues both by political scientists and economists, the current thesis extends our knowledge, by giving insight into some of abstention's unexplored but widely observed aspects.

The notion of spaces of orderings was introduced by Murray Marshall in the 1970's and provides an abstract framework for studying orderings on fields and the reduced theory of quadratic forms over fields. The structure of a space of orderings (X, G) is completely determined by the group structure of G and the quaternary relation (a_1, a_2) = (a_3, a_4) on G -- the groups with additional structure arising in this way are called reduced special groups. The theory of reduced special groups, in turn, can be conveniently axiomatized in the first order language L_SG. Numerous important notions in this theory, such as isometry, isotropy, or being an element of a value set of a form, make an extensive use of, so called, positive primitive formulae in the language L_SG. Therefore, the following question, which can be viewed as a type of very general and highly abstract local-global principle, is of great importance:<p>Is it true that if a positive primitive formula holds in every finite subspace of a space of orderings, then it also holds in the whole space?<p>This problem is now known as the pp conjecture. The answer to this question is affirmative in many cases, although it has always seemed unlikely that the conjecture has a positive solution in general. In this thesis, we discuss, discovered by us, first counterexamples for which the pp conjecture fails. Namely, we classify spaces of orderings of function fields of rational conics with respect to the pp conjecture, and show for which of such spaces the conjecture fails, and then we disprove the pp conjecture for the space of orderings of the field R(x,y). Some other examples, which can be easily obtained from the developed theory, are also given. In addition, we provide a refinement of the result previously obtained by Vincent Astier and Markus Tressl, which shows that a pp formula fails on a finite subspace of a space of orderings, if and only if a certain family of formulae is verified.

The theory of hypergeometric functions over finite fields was developed in the mid- 1980s by Greene. Since that time, connections between these functions and elliptic curves and modular forms have been investigated by mathematicians such as Ahlgren, Frechette, Koike, Ono, and Papanikolas. In this dissertation, we begin by giving a survey of these results and introducing hypergeometric functions over finite fields. We then focus on a particular family of elliptic curves whose j-invariant gives an automorphism of P1. We present an explicit relationship between the number of points on this family over Fp and the values of a particular hypergeometric function over Fp. Then, we use the same family of elliptic curves to construct a formula for the traces of Hecke operators on cusp forms in level 1, utilizing results of Hijikata and Schoof. This leads to formulas for Ramanujan’s -function in terms of hypergeometric functions.

Thesis (doctoral)--Universitate Litteraria Friderica Guilelma, 1835. / Vita.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaves 50-51). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaves 50-51). Also available on the Internet.

Thesis (doctoral)--Universität Zürich, 1905.

Not available / text

Vegetation mapping is often considered the process of identifying landscape patterns of individuals or clusters of species or life forms (LF). At the landscape scale, the larger pattern represented by individuals or clusters represents the conceptualization of "vegetation mapping" and can be used as a building block to describe an ecosystem. To represent these building blocks or LF a "common entity (CE)" concept is introduced to represent the components of Formations as described by the National Vegetation Classification (NVC) system. The NVC has established protocols to consistently represent plant communities and promote coordinated management, particularly across jurisdictional boundaries. However, it is not a universal standard and the methods of producing detailed maps of vegetation CE from very high spatial resolution (VHR) remote sensing data are important research questions.This research addressed how best to understand and represent plant cover in arid regions, the most effective methods of mapping vegetation cover using high spatial resolution data, how to assess the accuracy of these maps, and their value in establishing more standardized mapping protocols across ecosystems. Utilizing VHR products from the IKONOS and QuickBird sensors the study focused on the Coronado National Memorial and Chiricahua National Monument in Arizona and Los Ajos and Pinacate - Grand Desierto Biosphere Reserves in México. Individual CE were semi-automatically mapped incorporating spectral, textural and geostatistical variables. The results were evaluated across sensors, study sites, and input variables. In addition, multiple methods of acquiring field data for accuracy assessment were evaluated and then an evaluation was made of a semi-automatic determination of Formation based on CE.The results of the study suggest consistency across study sites using the IKONOSdata. A comparison between VHR products from the same place is feasible but sensor spectral differences may affect which derived bands would improve classification. CE classification procedures were not significantly different across sensors. The overall accuracy obtained for each Park was 59.5% for Chiricahua using QuickBird and 51.9% using IKONOS; at Pinacate 70.0% using IKONOS, and 55.9% for Ajos. Incorporating the geostatistical semi-variogram variables improved CE accuracy for some CE but not all.

No description available.