As the development of software applications and Internet, the security issues that come with get more serious. Buffer Overflow is an unavoidable problem while software programming. According to the advisories of each year, they show that many security vulnerabilities are from Buffer Overflow. Buffer Overflow is also the cause of intrusion made by hackers. The users of software applications usually depend on the software updates released by software venders to prevent the attacks caused by Buffer Overflow. So before applying software updates, that how to avoid attacks to software and prolong the save period of software is an important issue to prevent Buffer Overflow. By collecting and analyzing the exploit codes used by hackers, we can build the overall pattern of Buffer Overflow attacks, and we can take this pattern as the basis for preventing future Buffer Overflow attacks. Association rules can find the relations of unknown things, so it can help to build the common pattern between Buffer Overflow attacks. So this work applies association rules to build the pattern of Buffer Overflow attacks, and to find out the relations of system calls inside the exploit codes. We experiment and build a group of system call rules that can differentiate the attack behavior and the normal behavior. These rules can detect the Buffer Overflow attacks exactly and perform well in false positives. And then they can help to do further defenses after detecting attacks and alleviate the seriousness of Buffer Overflow attacks to computer systems.

Det pågår en intensiv debatt i Sverige om revisionspliktens vara eller inte vara i små aktiebolag. Sverige är ett av få europeiska länder som fortfarande har kvar en lagstadgad revisionsplikt för samtliga aktiebolag, och debatten är även av än mer intresse när Svensk redovisnings- och revisionsstandard alltmer anpassas till internationell standard. Ett medlemsland i Europeiska Unionen har möjligheten att undanta små aktiebolag från revisionsplikt. Men på grund av rådande regler i Sverige ska alla aktiebolag följa samma regler, något som ifrågasätts i debatten. Debatten om revisionsplikten är aktuell och viktig eftersom ungefär 200 000 aktiebolag skulle påverkas om revisionsplikten skulle tas bort. Det övergripande syftet med uppsatsen är att bidra till debatten om revisionsplikt för små aktiebolag, genom att gå bakom “ja- och nejdebatte.” Vi kommer att beskriva och förklara attityderna till revisionsplikten, samt till de existerande redovisningsreglerna hos mikroföretag i två olika branscher. För att uppfylla syftet har vi genomfört en kvalitativ studie. Vi har intervjuat ägarna till sex mikroföretag från två olika branscher, nämligen organisationskonsulter och byggnadsentreprenörer. De viktigaste slutsatserna från den här studien är, att oberoende av deras respektive attityd till revisionsplikten är det ingen av respondenterna, som skulle vilja ta bort revisionsplikten för små aktiebolag. Vidare uppfattar respondenterna inom byggnadsentreprenörsbranschen redovisningsreglerna som mer komplicerade än respondenterna inom organisationskonsultbranschen och en förenkling av reglerna skulle inte förändra någon av respon-denternas attityd till revisionsplikten / There is an extensive debate going on in Sweden about the being or not being of the statutory audit for small limited companies. Sweden is one of the few European countries that still have a statutory audit for all limited companies, and the debate is even more of immediate interest when the Swedish accounting and auditing standards are converging more and more to international standards. A member state in the European Union has the possibility to exempt small limited companies from the statutory audit. But due to the current regulations in Sweden, all limited companies are to follow the same rules, which is questioned in the debate. This debate is a current and important issue due to that approximately 200 000 limited companies would be affected if the statutory audit would be abolished. The overall purpose of this thesis is to contribute to the debate about the statutory audit for small limited companies, by moving beyond the “yes and no debate”. We will describe and explain the attitudes towards the statutory audit and the existing accounting regulations among micro companies in two different business sectors. In order to fulfil the purpose, we have conducted a qualitative study. We have interviewed the owners of six micro companies from two different business sectors, namely organizational consultants and building contractors. The main conclusions from this study are that independent of their respective attitudes towards the statutory audit, none of the respondents would like the statutory audit to be abolished for small limited companies. Further, the respondents within the building contractors business perceive the accounting rules as more complicated than the respondents within the organizational consultants sector do, and a simplification of regulation would not change any of the respondents’ attitudes towards the statutory audit.

The Canadian C-Spine (CS) and CT-Head (CT) Rules are tools aimed at improving the accuracy and efficiency of radiography use in emergency departments. This study evaluated whether the Theory of Planned Behaviour (TPB) could explain the inconsistent results from implementation studies of these two rules at 12 Canadian hospitals, where the same intervention resulted in a significant reduction in CS radiography but not CT radiography. It was demonstrated that the TPB model’s proposed relationships between constructs and behaviour could explain the ordering of CS but not CT radiography. However, after examining longitudinal changes of the TPB constructs, it was clear that these changes could not explain the changes in CS radiography ordering. Overall, TPB is unlikely to suggest important ways by which to improve radiography use, for CT because its constructs are not related to radiography ordering, and for CS because of high baseline levels of intention to clinically clear.

The goal of this thesis is to find provably correct methods for detecting conflicts between XACML rules. A conflict occurs when one rule permits a request and another denies that same request. As XACML deals with access control, we can help prevent unwanted access by verifying that it contains rules that do not have unintended conflicts. In order to help with this, we propose an algorithm to find these conflicts then use the Coq Proof Assistant to prove correctness of this algorithm. The algorithm takes a rule set specified in XACML and returns a list of pairs of indices denoting which rules conflict. It is then up to the policy writer to see if the conflicts are intended, or if they need modifying. Since we will prove that this algorithm is sound and complete, we can be assured that the list we obtain is complete and only contains true conflicts.

In this study, I used two independent perciform lineages (Neotropical Cichlidae and Nearctic Centrarchidae) to examine patterns of species richness and species coexistence a two spatial scales (e.g., macrohabitat and mesohabitat) and to examine inter-faunal patterns of ecomorphological convergence. The study was conducted during the low-water periods in four lowland rivers: the Cinaruco in Venezuela, the Tambopata in Peru, and the Neches and the Brazos rivers in Texas (USA). These rivers were chosen because of their similar characteristics, in terms of geomorphology, sediments, and water quality. The Cinaruco River and the Neches River have clear slightly-stained waters, whereas the Tambopata and the Brazos River have turbid waters with high loads of suspended sediments. I used morphological approaches as a surrogate to investigate patterns of species distribution in niche space, and predict patterns of species richness at different spatial scales. Despite high variation in the number of species in these two perciform assemblages, morphological analysis based on the means and standard deviations of nearest neighbor distance (NND) and mean distance to centroid (CD) revealed similar trends of morphological similarity in relation to species richness. Comparison of observed versus randomized data mesohabitat scale for all four rivers generally supported the niche expansion model of response to increase in species richness. At the scale of mesohabitats within rivers, most species assemblages appear to be organized by competitive interactions in accordance with the niche expansion model. The tropical species-rich Cinaruco River revealed particularly strong support for the niche expansion model. Intercontinental comparison of functional morphology and diets based on analysis of stomach contents and stable isotope ratios indicated broad morphological and dietary overlap between cichlid and centrarchid assemblages. For the most part, morphological ordinations showed that the two groups have diversified in a parallel manner within the confines of ram-suction modes of prey ingestion. This study concludes that even though differences are observed in historical and stochastic factors structuring fish assemblages in different geographic regions, consistent patterns of convergence at the species and assemblage levels results from natural selection under similar environmental conditions.

I investigated the role of extra-pair paternity on use of public information and the interaction between public information and personal information for patch fidelity decisions. It is unknown if songbirds use public information about the number of conspecific fledglings for patch fidelity decisions when extra-pair paternity is uncommon. I tested if probability of patch fidelity was associated with (1) number of fledglings in adjacent territories (public information), and (2) number of fledglings raised with a social mate (personal information). I used logistic regression to predict probability of patch fidelity of males and females based on the 2 uncorrelated predictor variables (Spearman’s rank correlation, S = 21895.28, n = 50, P = 0.723, r = –0.051). I monitored patch fidelity of 107 territories, counted the number of fledglings in each territory, and assessed parentage of 102 young from 36 nests for white-eyed vireos (Vireo griseus) from 2008–2010 in a 100 ha patch of woodland in central Texas, USA. I excluded the social male as the father of 3 of the 102 young and did not exclude any of the social females as the mother with parentage analysis using 6 microsatellite loci. The number of fledglings in adjacent territories was not a good predictor of probability of patch fidelity for males (beta 1 = 0.166, df = 35, P = 0.247, Nagelkerke’s R2 = 0.054) or females (beta 1 = 0.121, df = 17, P = 0.670, Nagelkerke’s R2 = 0.016). The number of fledglings raised with a social mate was also not a good predictor of probability of patch fidelity for males (beta 1 = –0.296, df = 43, P = 0.360, Nagelkerke’s R2 = 0.029), whereas it was a good predictor for females (beta 1 = 1.281, df = 21, P = 0.048, Nagelkerke’s R2 = 0.409). The dominant ecological concepts for explaining site fidelity in songbirds, win-stay lose-switch (based on personal reproductive success with a social mate) and public information, did not predict probability of patch fidelity well for male white-eyed vireos. The win-stay lose-switch model, but not public information was a good predictor of probability of patch fidelity for females. My results suggest that use of public information may depend on frequency of extra-pair paternity. Males may primarily use other information for patch fidelity decisions beyond reproductive success of conspecifics for patch fidelity decisions in some circumstances. My results support the need to ensure high levels of nesting success for females to return and maintain populations in areas managed for breeding songbirds for conservation efforts to be successful.

The Canadian C-Spine (CS) and CT-Head (CT) Rules are tools aimed at improving the accuracy and efficiency of radiography use in emergency departments. This study evaluated whether the Theory of Planned Behaviour (TPB) could explain the inconsistent results from implementation studies of these two rules at 12 Canadian hospitals, where the same intervention resulted in a significant reduction in CS radiography but not CT radiography. It was demonstrated that the TPB model’s proposed relationships between constructs and behaviour could explain the ordering of CS but not CT radiography. However, after examining longitudinal changes of the TPB constructs, it was clear that these changes could not explain the changes in CS radiography ordering. Overall, TPB is unlikely to suggest important ways by which to improve radiography use, for CT because its constructs are not related to radiography ordering, and for CS because of high baseline levels of intention to clinically clear.

The goal of this thesis is to find provably correct methods for detecting conflicts between XACML rules. A conflict occurs when one rule permits a request and another denies that same request. As XACML deals with access control, we can help prevent unwanted access by verifying that it contains rules that do not have unintended conflicts. In order to help with this, we propose an algorithm to find these conflicts then use the Coq Proof Assistant to prove correctness of this algorithm. The algorithm takes a rule set specified in XACML and returns a list of pairs of indices denoting which rules conflict. It is then up to the policy writer to see if the conflicts are intended, or if they need modifying. Since we will prove that this algorithm is sound and complete, we can be assured that the list we obtain is complete and only contains true conflicts.

La tesis de doctorado "Understanding, Evaluating and Selecting Voting Rules Through Games and Axioms" de Danilo Santa Cruz Coelho está compuesta de cuatro capítulos. La introducción es el primero y describe brevemente el contenido de los capítulos siguientes. En el Capítulo 2, en el contexto de un modelo de votación probabilística propuesto por Rae (1969), el autor investiga las consecuencias de elegir reglas de votación según el criterio de maximin. En el modelo, una regla de votación es el número mínimo de votantes favorables necesarios a una propuesta para que esta sea aceptada. El autor demuestra que la regla de votación que satisface el criterio de maximin puede ser distinta de la mayoría simple que es la que maximiza la suma de las utilidades esperadas de los votantes. El autor proporciona una caracterización de las reglas de votación que satisfacen el criterio de maximin. En el Capítulo 3, dos juegos que pueden ser inducidos por la regla de los k nombres son propuestos y analizados. El autor proporciona para cada uno de los juegos una caracterización del conjunto de los resultados del equilibrio fuerte de Nash. Estas caracterizaciones permiten al autor discutir las preferencias de los jugadores sobre diferentes variantes de la regla de los k nombres. Una parte importante de la regla de los k nombres es el procedimiento utilizado para seleccionar los k nombres que son propuestos al individuo que toma la decisión final. Seis reglas diferentes de selección que son utilizadas en la realidad por diferentes cuerpos decisorios alrededor del mundo son documentadas. En el Capítulo 4, el autor estudia si estas reglas satisfacen la propiedad de estabilidad. Una regla cumple esta propiedad si esta siempre selecciona un conjunto Weak Condorcet y cuando exista un conjunto con esta característica. El autor demuestra que todas estas seis reglas violan esta propiedad si los votantes no actúan estratégicamente. El autor entonces propone dos reglas estables. Finalmente, él proporciona dos justificaciones para el uso extensivo de las reglas inestables. / The dissertation entitled "Understanding, Evaluating and Selecting Voting Rules Through Games and Axioms" by Danilo Santa Cruz Coelho is composed of four chapters. The introduction is the first one and describes briefly the contents of the following chapters. In Chapter 2, in the context of a probabilistic voting model proposed by Rae (1969), the author investigates the consequences of choosing among threshold voting rules according to the maximin criterion. A threshold voting rule is given by the minimum number of votes needed to approve a proposal of change from the status quo. The author shows that the voting rules that satisfy the maximin criterion are different from the simple majority rule which is the one that maximizes the sum of voter's expected utilities. He provides a characterization of the threshold voting rules that satisfy this criterion as a function of the distribution of voters' probabilities to favour change from the status quo. In Chapter 3, two different game theoretical models that can be induced by the rule of k names are proposed and analysed. A characterization of the set of strong Nash Equilibrium outcomes of each of the games is provided. These characterizations enable the author to discuss the preferences of the players over different variants of the rule of k names. An important part of the rule of k names is the procedure used to screen out the k names to be proposed to the individual who takes the final decision. Six different screening rules which are used in reality by different decision bodies around the world are documented. In Chapter 4, he studies whether these screening rules satisfy stability. A screening rule is stable if it always selects a weak Condorcet set whenever such set exists. He shows that all of the six screening rules violate stability if the voters act not strategically. He then proposes two screening rules which satisfy stability. Finally, he provides two possible justifications for the widespread use of unstable screening rules.

The aim of this work was to design a set of rules for levodopa infusion dose adjustment in Parkinson’s disease based on a simulation experiments. Using this simulator, optimal infusions dose in different conditions were calculated. There are seven conditions (-3 to +3)appearing in a rating scale for Parkinson’s disease patients. By finding mean of the differences between conditions and optimal dose, two sets of rules were designed. The set of rules was optimized by several testing. Usefulness for optimizing the titration procedure of new infusion patients based on rule-based reasoning was investigated. Results show that both of the number of the steps and the errors for finding optimal dose was shorten by new rules. At last, the dose predicted with new rules well on each single occasion of majority of patients in simulation experiments.