Studies on bag models and properties of hadrons

This thesis is devoted to theoretical studies on the properties of hadrons on the basis of bag models. It contains some applications of the traditional.HIT bag model to the spectroscopy and decay of hadrons. The inadequacies of the model are brought out and a new version of the model, called the variable pressure bag model, is developed. Some of the Phenomenological applications of this model are discussed and the predictions are compared with experiment.

"Strictly models and objects first" - Unterrichtskonzept und -methodik für objektorientierte Modellierung im Informatikunterricht

Objektorientierte Modellierung (OOM) im Unterricht ist immer noch ein breit diskutiertes Thema - in der Didaktik akzeptiert und gewünscht, von der Praxis oft als unnötiger Overhead oder als schlicht zu komplex empfunden. Ich werde in dieser Arbeit zeigen, wie ein Unterrichtskonzept aufgebaut sein kann, das die lerntheoretischen Vorteile der OOM nutzt und dabei die berichteten Schwierigkeiten größtenteils vermeidet. Ausgehend von den in der Literatur dokumentierten Konzepten zur OOM und ihren Kritikpunkten habe ich ein Unterrichtskonzept entwickelt, das aus Erkenntnissen der Lernpsychologie, allgemeiner Didaktik, Fachdidaktik und auch der Softwaretechnik Unterrichtsmethoden herleitet, um den berichteten Schwierigkeiten wie z.B. dem "Lernen auf Vorrat" zu begegnen. Mein Konzept folgt vier Leitideen: models first, strictly objects first, Nachvollziehbarkeit und Ausführbarkeit. Die strikte Umsetzung dieser Ideen führte zu einem Unterrichtskonzept, das einerseits von Beginn an das Ziel der Modellierung berücksichtigt und oft von der dynamischen Sicht des Problems ausgeht. Da es weitgehend auf der grafischen Modellierungsebene verbleibt, werden viele Probleme eines Programmierkurses vermieden und dennoch entstehen als Ergebnis der Modellierung ausführbare Programme.

Optimising contributions of goat farming to household economic success and food security in three production systems in Ethiopia

The study aims to analyse factors affecting contributions of goat farming to household economic success and food security in three goat production systems of Ethiopia. A study was conducted in three districts of Ethiopia representing arid agro-pastoral (AAP), semi-arid agro-pastoral (SAAP) and highland mixed crop-livestock (HMCL) systems involving 180 goat keeping households. Gross margin (GM) and net benefit (NB1 and NB2) were used as indicators of economic success of goat keeping. NB1 includes in-kind benefits of goats (consumption and manure), while NB2 additionally constitutes intangible benefits (insurance and finance). Household dietary diversity score (HDDS) was used as a proxy indicator of food security. GM was significantly affected by an off-take rate and flock size interaction (P<0.001). The increment of GM due to increased off-take rate was more prominent for farmers with bigger flocks. Interaction between flock size and production system significantly (P<0.001) affected both NB1 and NB2. The increment of NB1 and NB2 by keeping larger flocks was higher in AAP system, due to higher in-kind and intangible benefits of goats in this system. Effect of goat flock size as a predictor of household dietary diversity was not significant (P>0.05). Nevertheless, a significant positive correlation (P<0.05) was observed between GM from goats and HDDS in AAP system, indicating the indirect role of goat production for food security. The study indicated that extent of utilising tangible and intangible benefits of goats varied among production systems and these differences should be given adequate attention in designing genetic improvement programs.

The Control of Human Arm Movement Models and Mechanical Constraints

A serial-link manipulator may form a mobile closed kinematic chain when interacting with the environment, if it is redundant with respect to the task degrees of freedom (DOFs) at the endpoint. If the mobile closed chain assumes a number of configurations, then loop consistency equations permit the manipulator and task kinematics to be calibrated simultaneously using only the joint angle readings; endpoint sensing is not required. Example tasks include a fixed endpoint (0 DOF task), the opening of a door (1 DOF task), and point contact (3 DOF task). Identifiability conditions are derived for these various tasks.

Economic crisis and the financial system amplification effect

A well informed and cautious financial system can improves the welfare outcome of an economy by driving lenders surplus to borrow-ers. Nevertheless in a crisis situation the financial system cautious behavior can become a crisis amplifier given that the credit approval conditions are hardly meet, so there could be a credit crunch even in a low interest rates environment. This paper illustrates the previous by developing a general equilibrium model where the collateral credit condition defines the prudential behavior of the financial sys-tem. This and some other conditions amplify the magnitude of a negative productivity shock.

The international economic crisis and the colombian economy

The purpose of this research is to provide an approximation to the likely effects of the crisis on the Colombian economy and to the effectiveness of policy response. For this, the most relevant transmission channels and policy measures are simulated in the setting of a static computable general equilibrium model (CGE). The results obtained are interesting in their own right and are in line with what could be expected given the information available on the behavior of the Colombian economy. Furthermore, they call into question the effectiveness of governmental intervention as judged by its intended countercyclical effects.

Economic integration. an overview of basic economic theory and other related issues

Este documento presenta una visión amplia de la Teoría de Integración Económica desde el punto de vista de la teoría de unión aduanera. Se argumenta que dicha teoría carece de integración y que los recientes desarrollos en el tema no parecen resolver esta falla. A pesar de esto, se sugiere que los desarrollos teóricos surgidos a partir del trabajo seminal de Viner y posteriormente desarrollados por otros teóricos, son aún útiles como herramienta de investigación empírica en el tema.

Economic shocks and crime: evidence from the crash of ponzi schemes

In November 2008, Colombian authorities dismantled a network of Ponzi schemes, making hundreds of thousands of investors lose tens of millions of dollars throughout the country. Using original data on the geographical incidence of the Ponzi schemes, this paper estimates the impact of their break down on crime. We find that the crash of Ponzi schemes differentially exacerbated crime in affected districts. Confirming the intuition of the standard economic model of crime, this effect is only present in places with relatively weak judicial and law enforcement institutions, and with little access to consumption smoothing mechanisms such as microcredit. In addition, we show that, with the exception of economically-motivated felonies such as robbery, violent crime is not affected by the negative shock.

Extractivism, economic diversification and prospects for sustainable development in Ecuador

The objectives of this paper are first, evaluating economic, social and environmental effects on oil extraction in Ecuador during the last 41 years, and second, discussing prospects to achieving a sustainable and equitable development path in the future, in the context of declining oil reserves. The current government is pursuing an extractivist policy, based on expanding oil extraction in formerly unexploited fields -including those inside the Yasuni National Park- and starting largescale mining exploitation. Two future options will be evaluated, first, an expansion of extractive activities, and second an alternative based on conservation, with sustainable use of natural resources (e.g. ecotourism, agroforestry, bio-knowledge), without expansion of oil field expansion and mining.