Small signal stability has always been an important concern for analog designers. Recent advances such as the Loop Finder algorithm allows designers to detect and identify local, potentially unstable return loops without the need to identify and add breakpoints. However, this method suffers from extremely high time and memory complexity and thus cannot be scaled to very large analog circuits. In this research work, we first take an in-depth look at the loop finder algorithm so as to identify certain key enhancements that can be made to overcome these shortcomings. We next propose pole discovery and impedance computation methods that address these shortcomings by exploring only a certain region of interest in the s-plane. The reduced time and memory complexity obtained via the new methodology allows us to extend automatic stability checking to much larger circuits than was previously possible.

This thesis explores and implements techniques for frequency domain modelling and time domain simulation of overhead transmission lines. The popular Vector Fitting algorithm is employed to approximate the frequency domain model using rational functions, and the recursive convolution technique is applied to the rational approximation to generate a time domain form. The frequency domain model is translated into the time domain using delay extraction, modal decomposition, passivity enforcement, and rational approximation. Several approaches to each of these procedures are investigated. The thesis also discusses several choices for the integration method used within the recursive convolution procedure. In order to make the transmission line modeller and simulator easy to use, a Java-based library and partial graphical interface were developed. Specifically, the goal was to develop a platform-independent program that can run either stand-alone or as an applet inside a web page. / October 2005

It might seem obvious that public opinions should be included in the planning process. However, it is not clear to what extent. Statutory forms of public participation attract little interest since many people feel that it is hard to make a difference. The purpose of this study was to engage those that normally do not get to speak their mind in the planning process. In this study, two methods for conducting “on-street surveys” were investigated. The place for the “on-street surveys” was Centralplan in Gävle. The two methods had different approaches. The “Stationary” method was a structured interview of pedestrians who had just crossed Centralplan. The “Follower” method was a structured interview that took place as the administrator and the participant crossed Centralplan in tandem. A total of 40 “Stationary” and 22 “Follower” interviews were conducted. The majority of the participants responded positively on making themselves heard within the planning process, indicating that they have important views to share. The methods used in this study can serve as an icebreaker for communication between planners and the public. / Det kan kännas självklart att allmänhetens åsikter ska vägas in i planeringsprocessen men i vilken utsträckning det ska ske är oklart. Lagstadgade former av medborgardeltagande väcker svalt intresse eftersom många upplever det som svårt att påverka. Syftet med den här studien var att engagera de människor som normalt inte kommer till tals i planeringsprocessen. I studien undersöktes två olika metoder för att genomföra gatuundersökningar, så kallade ”on-street surveys”. Platsen för genomförandet av gatuundersökningarna var Centralplan i Gävle. De två metoderna hade olika tillvägagångssätt. Metod ”Stationär” var en form av stillastående strukturerad intervju som utövades på platsen. Administratören frågade ut personer som alldeles precis hade förflyttat sig genom gaturummet. Metod ”Följeslagare” var en form av rörlig strukturerad intervju som utövades på platsen men där administratören slog följe med personen och ställde frågorna under tiden de passerade genom gaturummet. Totalt 62 personer medverkade i studien, varav 40 för metod ”Stationär” och 22 för metod ”Följeslagare”. Resultaten visade att allmänheten hade viktiga synpunkter att dela med sig av, till exempel om attityder och åsikter. Majoriteten av de medverkande ställde sig positiva till att få sin röst hörd inom planeringsprocessen. Metoderna som användes i studien skulle kunna fungera som dörröppnare för dialog mellan planerare och allmänheten.

The main topic of this thesis is the development of computational search methods that are useful in drug design applications. The emphasis is on exhaustiveness of the search method such that it can guarantee a certain level of geometric accuracy. In particular, the following two problems are addressed: (i) Prediction of binding mode of a drug molecule to a receptor and (ii) prediction of crystal structures of drug molecules. Predicting the binding mode(s) of a drug molecule to a target receptor is pivotal in structure-based rational drug design. In contrast to most approaches to solve this problem, the idea in this work is to analyze the search problem from a computational perspective. By building on top of an existing docking tool, new methods are proposed and relevant computational results are proven. These methods and results are applicable for other place-and-join frameworks as well. A fast approximation scheme for the docking of rigid fragments is described that guarantees certain geometric approximation factors. It is also demonstrated that this can be translated into an energy approximation for simple scoring functions. A polynomial time algorithm is developed for the matching phase of the docked rigid fragments. It is demonstrated that the generic matching problem is NP-hard. At the same time the optimality of the proposed algorithm is proven under certain scoring function conditions. The matching results are also applicable for some of the fragment-based de novo design methods. On the practical side, the proposed method is tested on 829 complexes from the PDB. The results show that the closest predicted pose to the native structure has the average RMS deviation of 1.06 °A. The prediction of crystal structures of small organic molecules has significantly improved over the last two decades. Most of the new developments, since the first blind test held in 1999, have occurred in the lattice energy estimation subproblem. In this work, a new efficient systematic search method that avoids random moves is proposed. It systematically searches through the space of possible crystal structures and conducts search space cuts based on statistics collected from the structural databases. It is demonstrated that the fast search method for rigid molecules can be extended to include flexible molecules as well. Also, the results of some prediction experiments are provided showing that in most cases the systematic search generates a structure with less than 1.0°A RMSD from the experimental crystal structure. The scoring function that has been developed for these experiments is described briefly. It is also demonstrated that with a more accurate lattice energy estimation function, better results can be achieved with the proposed robust search method.

This thesis seeks to examine why the Lavalas elite faction and its oppositions have failed to make and implement mutual agreements, to resolve regime crises and to create an environment conducive to democratic norms. The study derives explanations stemming from three alternative models: modernization, rational choice and misperception. Three periods of consensus-building attempt between the Lavalas elite and its oppositions (1991-1995: Consensus-Building attempt I; 1996-2000: Consensus-Building attempt II; 2000-2004: Consensus-Building attempt III) are considered. By using interpreted models a la Graham Allison, the thesis applies the criteria produced by each model to help interpret the failure of consensus-building in these three historical periods. The thesis' conclusion then assesses the models' strengths and weaknesses, prompting interesting questions for further research in the near future.

No description available.

BACKGROUND: When it comes to corporate decision making, the traditional rational model suggests that deliberative analysis yields good results. Thus, when contemplating strategic moves, executives are “required” to conduct deliberative analyses. As today’s business environment is becoming increasingly complex and fast-paced, however, executives often face the dilemma of having to make carefully considered strategic decisions on the one hand and not having enough time on the other hand. Intuition offers an efficient solution in this situation. PURPOSE: The purpose of this study is to investigate how corporate executives employ both rationality and intuition in making strategic decisions under uncertain, complex and time-pressured circumstances. RESEARCH METHOD: We conducted three face-to-face interviews with executives from three companies in Sweden. Each interview lasted around one hour.    RESULTS: Drawing on previous psychological and managerial research, we argue that rationality and intuition are better viewed as being complementary rather than separate. Findings from the study suggest that intuition could serve as an effective and efficient means for managers to make strategic decisions; and that intuition indeed plays a role in strategic decision making under complex, uncertain and time limited contexts.

The main topic of this thesis is the development of computational search methods that are useful in drug design applications. The emphasis is on exhaustiveness of the search method such that it can guarantee a certain level of geometric accuracy. In particular, the following two problems are addressed: (i) Prediction of binding mode of a drug molecule to a receptor and (ii) prediction of crystal structures of drug molecules. Predicting the binding mode(s) of a drug molecule to a target receptor is pivotal in structure-based rational drug design. In contrast to most approaches to solve this problem, the idea in this work is to analyze the search problem from a computational perspective. By building on top of an existing docking tool, new methods are proposed and relevant computational results are proven. These methods and results are applicable for other place-and-join frameworks as well. A fast approximation scheme for the docking of rigid fragments is described that guarantees certain geometric approximation factors. It is also demonstrated that this can be translated into an energy approximation for simple scoring functions. A polynomial time algorithm is developed for the matching phase of the docked rigid fragments. It is demonstrated that the generic matching problem is NP-hard. At the same time the optimality of the proposed algorithm is proven under certain scoring function conditions. The matching results are also applicable for some of the fragment-based de novo design methods. On the practical side, the proposed method is tested on 829 complexes from the PDB. The results show that the closest predicted pose to the native structure has the average RMS deviation of 1.06 °A. The prediction of crystal structures of small organic molecules has significantly improved over the last two decades. Most of the new developments, since the first blind test held in 1999, have occurred in the lattice energy estimation subproblem. In this work, a new efficient systematic search method that avoids random moves is proposed. It systematically searches through the space of possible crystal structures and conducts search space cuts based on statistics collected from the structural databases. It is demonstrated that the fast search method for rigid molecules can be extended to include flexible molecules as well. Also, the results of some prediction experiments are provided showing that in most cases the systematic search generates a structure with less than 1.0°A RMSD from the experimental crystal structure. The scoring function that has been developed for these experiments is described briefly. It is also demonstrated that with a more accurate lattice energy estimation function, better results can be achieved with the proposed robust search method.

<p>Large-scale, in vitro vaccine screening is an expensive and slow process, while rational vaccine design is faster and cheaper. As opposed to the emperical ways to design vaccines in biology laboratories, rational vaccine design models the structure of vaccines with computational approaches. Building an effective predictive computer model requires extensive knowledge of the process or phenomenon being modelled. Given current knowledge about the steps involved in immune system responses, computer models are currently focused on one or two of the most important and best known steps; for example: presentation of antigens by major histo-compatibility complex (MHC) molecules. In this step, the MHC molecule selectively binds to some peptides derived from antigens and then presents them to the T-cell. One current focus in rational vaccine design is prediction of peptides that can be bound by MHC.<p>Theoretically, predicting which peptides bind to a particular MHC molecule involves discovering patterns in known MHC-binding peptides and then searching for peptides which conform to these patterns in some new antigenic protein sequences. According to some previous work, Hidden Markov models (HMMs), a machine learning technique, is one of the most effective approaches for this task. Unfortunately, for computer models like HMMs, the number of the parameters to be determined is larger than the number which can be estimated from available training data.<p>Thus, heuristic approaches have to be developed to determine the parameters. In this research, two heuristic approaches are proposed. The rst initializes the HMM transition and emission probability matrices by assigning biological meanings to the states. The second approach tailors the structure of a fully connected HMM (fcHMM) to increase specicity. The effectiveness of these two approaches is tested on two human leukocyte antigens(HLA) alleles, HLA-A*0201 and HLAB* 3501. The results indicate that these approaches can improve predictive accuracy. Further, the HMM implementation incorporating the above heuristics can outperform a popular prole HMM (pHMM) program, HMMER, in terms of predictive accuracy.

This essay takes the three models from Allison and Zelikow book Essence of decision and applies them on the Swedish defense system. After the cold war the Swedish defense system had to undergo changes to be a more modern defense and be able to defend Sweden against threats. To also be able to cooperate with other countries in peacekeeping operations the Swedish defense had to be reorganized. The solution was to change direction from a defense system that was organized for invasion to instead be a movable defense ready for any challenge in Sweden or abroad. This reorganization will be analyzed according to the three different models.