The Role of Phylogenetic Constraints in the Evolution of Pollination Mechanisms in Iridaceae of Sub-Saharan Africa

Novel, specialized systems exploiting bibionid flies, oil-collecting bees, wasps, or crepuscular settling moths as pollen vectors are added to the range of recorded pollination mechanisms in sub-Saharan Africa Iridaceae, while knowledge of the pollination of previously understudied genera such as Aristea, Bahiana, Ferraria, Hesperantha, and Tritoniopsis is expanded. The pollination of 357 species of the sub-Saharan African Iridaceae now includes 17 discrete systems. Based on repetitive interlinked suites of floral attractants and rewards we now infer pollination mechanisms for an additional 883 species. Many pollination systems recur in genera containing \u3e 10 species. The ancestral pollination in African Iridaceae, and also the most common one, involves large, long-tongued bees that contact anthers or stigmas passively while foraging for nectar. Some 182 species (in 11 genera) lack nectar or oil and pollinators forage preferentially for pollen. Our earlier hypothesis that the diversity of pollination mechanisms within a lineage increases via adaptive radiation and/or character displacement involving simple shifts in floral presentation is expanded to include the role of phylogenetic constraint. Specifically, possession of the meranthium flower in Moraea (ca. 195 spp.) and Ferraria (ca. 14 spp.) of subfamily Iridoideae limits the number of pollination shifts in these genera. More pollination shifts occur in subfamily Crocoideae (ca. 1000 spp.) because the ancestral flower includes tepals united basally into a floral tube and bilateral symmetry. With 16 derived pollination mechanisms described for this family in sub-Saharan Africa it is obvious that phylogenetic constraint is sufficiently flexible to explain the shifts in pollination mode

Development of a simulation and evaluation environment for a traffic flow analysis system.

A system for analysis of the traffic flow on public streets and highways through the use of Floating Car Data (FCD) relies completely on the number of simultaneously contributing vehicles, a fact that is no barrier for the phases of conception and development but poses a serious issue for the testing of such a system. Especially for smaller institutions or companies where the ability and resources to field the required number of participants is not given which in turn leads to the need for computational support to substitute the use of real vehicles by simulation. This thesis focuses on the task of the design and development of a simulation and evaluation environment for a pre-developed Traffic Flow Analysis System. The objective of this environment is to simulate the behavior of real vehicles on the existing street network including their most relevant characteristics for the purpose of congestion recognition. It is shown how simulation methods can be effectively used to create such an environment while using mathematical methods to model the characteristics of the participating system parts (vehicles) as well as the environmental influence on the external communication components (GPS, Radio)

Dynamics of policymaking : stepping back to leap forward, stepping forward to keep back

We study dynamic policy-making when: today's policy agreement becomes tomorrow's status quo; agents account for the consequences of today's policies for future policy outcomes; and there is uncertainty about who will hold future political power to propose and veto future policy changes. Today's agenda-setter holds back from fully exploiting present opportunities to move policy toward her ideal point whenever future proposer and veto players are likely to be aligned either in favor of reform, or against it. Otherwise, agenda-setters advance their short-run interests. Optimal proposals can vary discontinuously and non-monotonically with political fundamentals

Reelection and renegotiation : the political economy of international agreements

We study dynamic international agreements when one of the negotiating parties faces a threat of electoral replacement during negotiations, when agreements made before the election are the starting point for any subsequent renegotiation, and when governments cannot commit to future negotiation strategies. Conflicts of interest between governments may be softened or intensified by the governments’ conflicts of interest with voters. We characterize when the threat of electoral turnover strengthens the prospect for successful negotiations, when it may cause negotiations to fail, and how it affects the division of the surplus from cooperation. We also show how changes in domestic politics—including uncertainty about the preferences of domestic political parties—affect a domestic government’s ability to extract greater concessions in negotiations

Marine Pollution and the Law of the Sea

This article reviews, Marine Pollution and the Law of the Sea, by John Warren Kindt, published by William S. Hem & Co., Inc. in 1986

The race to the base

We study multi-district legislative elections between two office-seeking parties when the election pits a relatively strong party against a weaker party ; when each party faces uncertainty about how voter preferences will evolve during the campaign; and, when each party cares not only about winning a majority, but also about its share of seats in the event that it holds majority or minority status. When the initial imbalance favoring one party is small, each party targets the median voter in the median district, in pursuit of a majority. When the imbalance is moderate, the advantaged party continues to hold the centre-ground, but the disadvantaged party retreats to target its core supporters; it does so to fortify its minority share of seats in the likely event that it fails to secure a majority. Finally, when the imbalance is large, the advantaged party advances toward its opponent, raiding its moderate supporters in pursuit of an outsized majority

Ermittlung des Energiebedarfs zur Bewegung von Fahrzeugen in mikroskopischen Verkehrssimulationen

Die Integration von Modellen für Fahrzeuge mit alternativen Antrieben in Verkehrssimulationen erfordert eine genauere Betrachtung der Energieflüsse in den einzelnen Fahrzeugen. Diese Arbeit betrachtet den Energiebedarf für die Bewegung von Fahrzeugen und evaluiert vorhandene klassische Modelle zur Abstraktion der physikalischen Einflüsse. Aufgrund der fehlenden Einstimmigkeit der Autoren bei der Beschreibung solcher Modelle in der Literatur wird letztlich der Ansatz verfolgt, ein entsprechendes Modell von der physikalischen Basis ausgehend neu zu entwickeln. Zusätzlich dazu wird festgestellt, dass die Beschränkungen der geläufigen Verkehrssimulationsumgebungen einen signifikanten Einfluss auf die Berechenbarkeit einzelner Komponenten derartiger Modelle haben. Das geschaffene Modell wird anschließend in verschiedenen Varianten in einem Vergleich mit einem weit verbreiteten Modell evaluiert. Zu guter Letzt muss konstatiert werden, dass eine Erhöhung der Realitätsnähe der Simulation – insbesondere im situativen Bereich – erreicht werden konnte, für wesentliche Verbesserungen jedoch eine Beseitigung bestehender Restriktionen der Simulationsumgebungen erforderlich wäre.The integration of models for alternative fuel vehicles in traffic simulation requires a closer examination of the energy flows in the individual vehicles. This work considers the energy required for the movement of vehicles and evaluates existing classical models for the abstraction of the physical influences. Due to the lack of unanimity of the authors in the discribing of such models in the literature, the approach ultimately pursued requires redeveloping an appropriate model of the physical basis as a starting point. Additionally, it has been established that the restrictions of the common traffic simulation environments have a significant impact on the computability of individual components of such models. The created model is then evaluated in different variants in comparison with a widely used model. Finally, it is notable that increasing simulation realism could be achieved, however, for in order to see substantial improvements, the elimination of certain restrictions of current simulation environments would be required