Voice over IP (VoIP) is a key enabling technology for the migration of circuit-switched PSTN architectures to packet-based IP networks. However, this migration is successful only if the present problems in IP networks are addressed before deploying VoIP infrastructure on a large scale. One of the important issues that the present VoIP networks face is the problem of unwanted calls commonly referred to as SPIT (spam over Internet telephony). Mostly, these SPIT calls are from unknown callers who broadcast unwanted calls. There may be unwanted calls from legitimate and known people too. In this case, the unwantedness depends on social proximity of the communicating parties. For detecting these unwanted calls, I propose a framework that analyzes incoming calls for unwanted behavior. The framework includes a VoIP spam detector (VSD) that analyzes incoming VoIP calls for spam behavior using trust and reputation techniques. The framework also includes a nuisance detector (ND) that proactively infers the nuisance (or reluctance of the end user) to receive incoming calls. This inference is based on past mutual behavior between the calling and the called party (i.e., caller and callee), the callee's presence (mood or state of mind) and tolerance in receiving voice calls from the caller, and the social closeness between the caller and the callee. The VSD and ND learn the behavior of callers over time and estimate the possibility of the call to be unwanted based on predetermined thresholds configured by the callee (or the filter administrators). These threshold values have to be automatically updated for integrating dynamic behavioral changes of the communicating parties. For updating these threshold values, I propose an automatic calibration mechanism using receiver operating characteristics curves (ROC). The VSD and ND use this mechanism for dynamically updating thresholds for optimizing their accuracy of detection. In addition to unwanted calls to the callees in a VoIP network, there can be unwanted traffic coming into a VoIP network that attempts to compromise VoIP network devices. Intelligent hackers can create malicious VoIP traffic for disrupting network activities. Hence, there is a need to frequently monitor the risk levels of critical network infrastructure. Towards realizing this objective, I describe a network level risk management mechanism that prioritizes resources in a VoIP network. The prioritization scheme involves an adaptive re-computation model of risk levels using attack graphs and Bayesian inference techniques. All the above techniques collectively account for a domain-level VoIP security solution.

Thesis (MA)--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: This thesis explores the existence of misperceptions regarding the peer‐drinking norm among undergraduate students at Stellenbosch University and the role of these misperceptions in explaining students’ drinking behaviour. A more permissive perception of the drinking norm has been associated with heavier alcohol consumption and negative consequences for oneself, others and property. Perceptions of the academic norm and its relation to personal academic and drinking behaviour are also investigated. Furthermore, the study examines the role of perceptions of the drinking norm in personal drinking behaviour in the context of other cognitive factors (perceptions), experiences prior to enrolling at university, as well as socio‐demographic and contextual factors. The theoretical framework used to understand the origin, occurrence and perpetuation of misperceptions regarding the social norm includes Bourdieu’s theory of habitus, social norms theory, social learning theory and attribution theory. Data were collected from 640 students out of a random sample of 3 177 who had been invited to participate in a web‐based survey during September 2009. In addition, 18 personal semi‐structured interviews were conducted with students.   Similar to findings of research in other countries, the results of this research show that students at Stellenbosch University tend to perceive other students’ drinking behaviour (descriptive norm) and approval of drinking behaviour (injunctive norm) as more permissive than their own. The degree of misperception increases as the social distance of reference groups increases and is also significantly related to personal alcohol consumption. There is also evidence of misperceptions regarding the academic norm and its association with personal drinking behaviour and academic behaviour. Multiple regression analysis reveals that the perceived drinking norm of close friends is the best predictor of personal drinking behaviour, followed by personal approval of drinking and drinking behaviour during the last year of high school. The data presented here for Stellenbosch University students extend the evidence that peer drinking norms are misperceived and highlights the importance of a student’s experiences before enrolling at university. Furthermore, it provides evidence that misperceiving the drinking norm is a pervasive problem that may have behavioural consequences. Various American higher education institutions have developed and implemented campaigns aimed at correcting these misperceptions. This has resulted in significant reductions in misperceptions as well as in heavy drinking among students. Students at Stellenbosch University and elsewhere might also benefit from these types of intervention strategies. / AFRIKAANSE OPSOMMING: Hierdie tesis ondersoek die bestaan van wanpersepsies aangaande die portuurgroep‐drinknorm onder voorgraadse studente aan Universiteit Stellenbosch en die rol daarvan in die verduideliking van studente se drinkgedrag. ’n Meer liberale persepsie van die drinknorm hou verband met swaarder alkoholgebruik en meer negatiewe gevolge vir die persoon self, ander en eiendom. Die studie ondersoek ook persepsies van die akademiese norm en die verband daarvan met persoonlike akademiese en drinkgedrag. Verder word die rol van persepsies van die drinknorm in persoonlike alkoholgebruik in die konteks van ander bewussynsfaktore (persepsies), ervarings voor inskrywing by die universiteit, asook sosiaal‐demografiese en kontekstuele faktore ondersoek. Die studie maak gebruik van die teoretiese raamwerke van Bourdieu se habitus, sosiale norm‐teorie, sosiale leer‐teorie en attributasieteorie om die oorsprong, aanwesigheid en voortsetting van wanpersepsies te verstaan. Data is versamel onder 640 studente uit ’n ewekansige steekproef van 3 177 studente wat uitgenooi was om gedurende September 2009 aan ’n webgebaseerde opname deel te neem. Daar is ook 18 in‐diepte semi‐gestruktureerde onderhoude met studente gevoer.   Soortgelyk aan bevindinge van navorsing in ander lande, toon resultate van hierdie navorsing dat studente aan Universiteit Stellenbosch geneig is om ander studente se drinkgedrag (beskrywende norm) en goedkeuring van alkoholverbruik (injunktiewe norm) as meer liberaal as hulle eie waar te neem. Die graad van wanpersepsie neem toe namate die sosiale afstand van verwysingsgroepe toeneem en hou ook betekenisvol verband met persoonlike alkoholgebruik. Daar is ook bewyse van wanpersepsies aangaande die akademiese norm en die verband daarvan met persoonlike drink‐  en akademiese gedrag. Resultate van ’n meervoudige regressie‐ontleding wys dat die waargenome drinknorm van goeie vriende die beste voorspeller van persoonlike drinkgedrag is, gevolg deur persoonlike goedkeuring van alkoholgebruik en drinkgedrag gedurende die laaste jaar van hoërskool. Die data van Stellenbosse studente lewer verder bewys dat portuurgroep‐drinknorme verkeerdelik waargeneem word en beklemtoon die belangrikheid van studente se vorige ervarings. Dit bewys ook dat die verkeerde waarneming van die drinknorm ’n konstante probleem is wat gedragsgevolge kan hê. Verskeie Amerikaanse universiteite het al veldtogte ontwikkel en geïmplementeer gemik op die regstel van dié wanpersepsies, en dit het wanpersepsies en swaar drankgebruik onder studente betekenisvol verminder. Studente aan Universiteit Stellenbosch en elders sal waarskynlik ook by soortgelyke intervensiestrategieë baat vind. / jfl2011 / Imported from http://etd.sun.ac.za

Excerpt:Misperceptions about personal weight are common and include both under- and overestimates.1–6 Overweight misperception is found among both males and females across different racial/ethnic and age groups but is generally more common among females. Studies also indicate that body weight misperception is common among university students.2,4,7,8 In a study assessing the prevalence of weight misperception among U.S. college students, 12.9% of students had inflated body weight perception and 15.1% considered themselves to be thinner than they actually were.7 Gender and racial/ethnic differences in weight misperception have been observed among normal-weight college adults. According to the 2008 National College Health Assessment (NCHA), 28.8% of college females and 39.4% of college males were overweight or obese. However, more females (38.0%) than males (30.8%) described themselves as overweight or obese.8 Non-Hispanic white people are also more likely to report overweight misperception than other racial/ethnic minority groups.8,9

Syfte och frågeställningar: Syftet med studien var att i) undersöka validiteten i befolkningens skattning av stillasittande (SED) respektive måttlig till kraftig fysisk aktivitet (MVPA) samt ii) beskriva eventuella skillnader mellan de som under-, över- respektive korrekt skattar sitt beteende. Följande frågeställningar utformades: 1) Förekommer diskrepans mellan deltagarnas subjektiva skattning av SED och MVPA jämfört med objektivt mätt fysisk aktivitet med accelerometer? 2) Skiljer sig de deltagare som under-, över- respektive korrekt skattar sitt beteende avseende kön, socioekonomisk status, BMI, konditionsvärde respektive självskattad hälsa? Metod: Studien använder data från the Swedish CArdioPulmonary bioImage Study (SCAPIS) pilotstudie där deltagarna besvarade ett frågeformulär samt bar en accelerometer i sju på varandra följande dagar (N = 652). I denna studie har fyra frågor använts ur SCAPIS deltagarenkät för att mäta deltagarnas subjektiva nivå av fysiska aktivitet. Diskrepans av SED respektive MVPA räknades fram som subjektivt skattad tid (enkätfrågorna) minus accelerometerns registrerade tid. Data beskrivs deskriptivt där populationen har kategoriserats i kvintiler utefter medianskillnaden mellan subjektivt skattad och objektivt mätt tid. Resultat: Medianvärdet för diskrepans av SED och MVPA var -180,2 min/dag (under-) respektive 18,6 min/dag (överskattning). Avseende diskrepans av SED föreligger signifikanta skillnader mellan kvintilerna för diskrepans av SED (p = 0,000), accelerometermätt tid i SED (p = 0,000) samt totalt antal registrerade minuter (p = 0,000). Inga signifikanta skillnader ses för kön (p = 0,744), socioekonomisk status (p = 0,986), BMI (p = 0,806), konditionsvärde (p = 0,727) eller självskattad hälsa (p = 0,385). Avseende diskrepans av MVPA föreligger signifikanta skillnader för diskrepans av MVPA (p = 0,000), accelerometer-mätt tid i både SED (p = 0,000) och MVPA (p = 0,000), antal registrerade minuter totalt (p = 0,001), socioekonomisk status (p = 0,001) samt självskattad hälsa (p = 0,009). Slutsats: Resultaten visar att det är en stor diskrepans mellan hur svenska medelålders män och kvinnor skattar SED respektive MVPA om man jämför med objektivt accelerometermätt tid. Det verkar dock inte finnas en viss kategori människor som under- eller överskattar SED mer än andra avseende de undersökta variablerna. Beträffande diskrepans av MVPA ses dock en tendens till ökad diskrepans för de som bor i socioekonomiska högstatusområden samt att de med god självskattad hälsa överskattar mer. Studiens resultat tyder även på att mer registreringstid med accelerometern medför ökad diskrepans av SED respektive MVPA. Mer forskning kring hur olika registreringstider påverkar utfallen är därför önskvärt. / Aim: The aim of this study was to i) examine the validity of the population estimates of sedentary behaviour (SED) and moderate to vigorous physical activity (MVPA) and ii) describe possible differences between groups that are under-, over- and correctly classifying their behaviour. The following questions were designed to answer the above aim: 1. Are there discrepancies between the participants self-reported SED and MVPA compared to objective measurement by accelerometer? 2. Do the participants who under-, over- and correctly classify their behaviour differ with respect to gender, socioeconomic status, fitness factor and self-rated health? Method: This study used data from the Swedish CArdioPulmonary bioImage pilot Study  (SCAPIS) where participants answered a questionnaire and wore an accelerometer for seven subsequent days (N = 652). Four questions were used to measure the participants’ physical activity level. Discrepancy of SED and MVPA was calculated as the difference between subjectively and objectively measured time. The data is descriptively presented where misclassification has been categorized into quintiles and estimated as median differences. Results: The median time for discrepancy of SED was for the whole population -180,2 min/day (under-) and for MVPA 18,6 min/dag (overestimation). Regarding discrepancy of SED, there were significant differences between quintiles for discrepancy of SED (p = 0,000), accelerometer-registered time in SED (p = 0,000) and total number of minutes registered (p = 0,000). No significant differences existed for gender (p = 0,744), socioeconomic status (p = 0,986), BMI (p = 0,806), fitness factor (p = 0,727) or self-rated health (p = 0,385). Regarding discrepancy of MVPA there were significant differences for discrepancy of MVPA (p = 0,000), accelerometer-registered time in SED (p = 0,000) and MVPA (p = 0,000) and total number of minutes registered (p = 0,001). Significance also existed for socioeconomic status (p = 0,001) and self-rated health (p = 0,009). Conclusion: The results show that the population in this study misclassify SED and MVPA and the differences between the quintiles are large. However, there seems to be no particular category of people who misclassify SED more than others in regards to the examined variables. Concerning discrepancy of MVPA, the results suggest that the discrepancy is greater for those with high socioeconomic status and that those with good self-rated health tend to overestimate more. The results also suggest that more time registered with accelerometer entails greater discrepancy. More research examining how different recording times affect outcomes is warranted. / <p>Kursen Projektarbete.</p><p>SCAPIS-projektet</p>

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Die vorliegende Dissertation besteht aus vier Kapiteln zum Thema Steuerfehlwahrnehmung. Kapitel 1 gibt einen Überblick über die bisherige Literatur und systematisiert sie durch die Entwicklung des Behavioral Taxpayer Response Model. Das Ausmaß der Steuerfehlwahrnehmung wird u.a. durch die Verfügbarkeit von Informationen und persönliche Merkmale beeinflusst. Auch wenn Steuerinformationen verfügbar sind, schätzen die Steuerpflichtigen die Steuerlast falsch ein, weil sie sich in einem begrenzten Maße rational verhalten. Die umfangreiche Literatur zeigt auch, dass es nur wenig Literatur in Bezug auf Unternehmen gibt. Wir schließen diese Forschungslücke in Kapitel 2, indem wir die Fehlwahrnehmung durch Unternehmen in Deutschland analysieren. Um Datenbeschränkungen zu überwinden, verwenden wir einen innovativen Ansatz, der robuste Schätzungen liefert. Im Allgemeinen nehmen die Unternehmen ihre durchschnittlichen Steuersätze und Grenzsteuersätze deutlich verzerrt wahr und haben Probleme mit dem Konzept des Grenzsteuersatzes. Fehlwahrnehmungen werden tendenziell von der Komplexität, dem Steuerwissen und der Unzufriedenheit mit dem Steuersystem beeinflusst. Im Zusammenhang mit der Vermögensbesteuerung zeigen wir in Kapitel 3 anhand eines Umfrageexperiments, dass die Fehlwahrnehmung der jährlichen Vermögensteuer aufgrund ihrer mathematischen Komplexität zu einer verzerrten Präferenz führt. Die Information über die tatsächliche Steuerbelastung führt zu deutlich niedrigeren präferierten Steuersätzen. In dem abschließenden Kapitel 4 überprüfen wir die Ergebnisse einer Studie zur Steuervermeidung, die von den Grünen/EFA im Europäischen Parlament in Auftrag gegeben wurde. Diese Studie erregte große Aufmerksamkeit, weil sie behauptete, dass Unternehmen in Deutschland weit weniger Steuern zahlen, als der gesetzliche Steuersatz vermuten ließe. Wir zeigen, dass die Ergebnisse falsch sind und tragen damit zur Steuertransparenz in Deutschland bei. / This dissertation consists of four chapters on tax misperception. Chapter 1 reviews the previous literature on tax misperceptions and systematizes it through the development of the Behavioral Taxpayer Response Model. The extent of tax misperception is determined by information availability and personal characteristics. Under the assumption that tax information is available, taxpayers may even misperceive the tax burden because they behave in a rational bounded manner. The extensive literature also shows that there is little literature on corporations. We address this research gap in Chapter 2, which analyzes the misperception of tax rates by firms in Germany. To overcome data limitations, we use an innovative approach to measure tax misperception that provides robust estimates. In general, firms significantly misperceive their average (ATR) and marginal tax rates (MTR) and have problems with the concept MTR. Misperceptions tend to be influenced by the complexity of the tax system, tax knowledge, and satisfaction with the current tax system. In the context of wealth taxation, we use a survey experiment in Chapter 3 to show that misperception of a yearly wealth tax, due to its mathematical complexity, leads to a biased preference for wealth taxation. Informing respondents about the actual tax burden leads to significantly lower preferred tax parameters. In the final Chapter 4, we question the findings of a study on tax avoidance commissioned by the Greens/EFA in the European Parliament. This study attracted media attention because it claimed that companies in Germany pay far less tax than the statutory tax rate would suggest. We demonstrate that their findings are wrong and help to increase tax transparency in Germany.

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The thesis: "The Causes of Iraqi War: Why the US Administration decided to invade Iraq in 2003" focuses on explanation why the administration of the USA made that step. The specification of the roots of war is based on five causes and seventeen subcauses according to the essay of Stephen Van Evera and other scholars, and the paper trough the methodology of text's analyzes investigates behavior, decision-making process and motivations of the US administration (the level of units) and some steps of the US president G. W. Bush (individual level) in the process leading to the war in Iraq. Concerning the causes of war, the paper introduces different concepts of the offense-defense balance and analyzes whether the balance was disrupted. Secondly, it examines the role of cumulative resources in Iraq like oil, territory and state structures and it shows how they influenced the decision. Third, it searches for the linkage among an emergence of a new threat and responses to it which mouthed to the acceptance of the concept of the first move advantage. Fourth, the thesis accounts for the roots of misperception, where they originate and how they operated in perception of the US administration of the Iraqi threat. Finally, the investigation of the last root of conflict explains why and how windows of...