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In recent years, social networks and their related theories and applications attract widespread attentions in computer science. Many applications are designed by exploring the social information among users, such as social peer-to-peer systems, mobile cloud, and online recommendation systems. Most of the existing works only focus on how to use social information but ignore the fact that social information itself may cause severe security and privacy problems. In this dissertation, we first present some social information-assisted application systems that we have designed, and then, we present several social information-involved privacy and security risks and their countermeasures. Generally speaking, the design procedure of any social information-assisted application involves three tasks: publishing, accessing, and using social information. However, all of these tasks contain privacy and security issues. Social information can be published from a centralized system or a distributed one. For the centralized scheme, the social information is directly published from online social networking systems, such as Facebook or Twitter. However, we found that the data of a social network essentially is a time-evolving graph. Most of the existing approaches fail to preserve users' identity privacy once a malicious attacker has the external knowledge about the victim's time-varying behaviors. For avoiding the new privacy issue, we propose a time-based anonymization scheme. For the distributed social information-sharing scheme, each user's information is propagated from friend to friend's friends, and so on. We design a new scheme to gradually enhance the privacy protection along a propagation path, in the meanwhile, maximally preserve the overall utility of the user's data. From a data accessing aspect, social information can be used by malicious users for launching new attacks. In this dissertation, we find a friendship-based privacy disclosure attack, and a corresponding defense approach is designed. Location-based service has been widely adopted. In order to preserve location privacy, users usually turn off the corresponding applications when visiting sensitive locations. However, once social relationships are known, attackers are able to infer these hidden locations, which disclose users' location privacy. For preserving the location privacy, we design a fake location-based approach, which efficiently disorders the social-geographic relationships among users. From the data usage aspect, social information and its related data may come from users. A system may lose functioning if some malicious users inject plenty of fake information. Mobile clouds and Friend Locator are two typical systems, which are vulnerable to the fake information-related attacks. Mobile clouds explore the idle computing resources of surrounding devices by recruiting nearby friends to participate in the same task. However, malicious users may inject wrong friendships information to mess up the system. When visiting a new place, Friend Locator provides navigation services for participators by creating a map based their trajectories. The functioning of the system is based on the trust among participators. Once a user's device is controlled by attackers, all other users may receive wrong navigation. For defending these attacks, we provide different countermeasure. / Computer and Information Science

While both social information processing and cortisol secretion in childhood aggression have generated a great deal of interest and research in the past few decades, these social-cognitive and physiological components of aggressive behavior have not been examined in the context of an integrative model. This lack of an integrative framework may underlie some of the inconsistencies that have plagued the literature in this area to date, especially with respect to hypothalamic-pituitary-adrenal (HPA) axis functioning in aggressive children. This investigation tested a mediational model of the relationship between social-information processing, cortisol secretion, and reactive and proactive aggression. Specifically, it was hypothesized that social-information processing variables would mediate the proposed relationship between reactive and proactive aggression and cortisol secretion. One hundred and twenty-six children between the ages of 13 and 18 were administered the Child Behavior Rating Form (CBR), the Home Interview with Child (HIC), the Response Decision and Social Goals Instrument (RDSGI), the Antisocial Processes Screening Device (APSD), the Buss-Durkee Hostility Inventory (BDHI), the Children's Depression Inventory (CDI), and the Revised Children's Manifest Anxiety Scale (RCMAS). Each child also contributed two samples of saliva for cortisol assay, and each child's teacher completed a teacher-version of the APSD and the CBR. Regression analyses revealed no significant associations between proactive or reactive aggression and cortisol secretion, or between any of the social-information processing variables and cortisol secretion. Predicted associations between proactive and reactive aggression and social-information processing variables were found. Overall, therefore, the mediational model was not supported. However, cortisol secretion was found to be associated with both anxiety and depression, and exploratory analyses revealed significant associations between cortisol secretion and Psychopathy as measured by the APSD. Taken together, the findings suggest that while the specific relationship proposed here among social-cognitive, psychophysiological, and behavioral variables was not found, an integrative model examining each of these components may be useful in further investigations of the complex phenomenon of childhood aggression. / Ph. D.

The present study investigated the impact of certain and uncertain socialinformation on pain perception and memory. We hypothesized that theuncertain feedback group would experience higher pain intensity. Further, thatthe uncertain group would remember fewer pictures than the certain group.Participants were 42 undergraduate students from a medium-sized universityin Sweden who received, depending on group assignment, either certain oruncertain feedback about the pain intensity in the upcoming cold-pressor test.Following feedback, the participants performed two categorization tasksduring which they had to indicate whether the picture showed a living thing oran object. During the second task they also had to perform the cold-pressortest. Thirty minutes after the cold-pressor test participants performed asurprise recall test with regard to the pictures presented during thecategorization tasks. The two groups did not differ in self-reported uncertaintyabout their expectation of pain during the cold-pressor test but the uncertainfeedback group expected the cold-pressor test to be more painful than thecertain feedback group. We found no differences between the groups in eitherperception or recall. Finally, recall was impaired for pictures presentedduring the cold-pressor test, independent of group. In sum, our hypotheseswere not supported. Suggestion for future research is to manipulate thefeedback in another way to make it clearer for the participants. / Den aktuella studien utredde betydelsen av osäker och säker socialinformation för smärtintensitet och minne. Studiens hypotes var att den osäkragruppen skulle uppleva högre smärtintensitet och att den osäkra gruppenskulle komma ihåg mindre bilder än den grupp som fick säker information.Deltagarna var 42 studenter på ett medelstort universitet i Sverige, beroendepå vilken grupp de hamnade i fick de antingen osäker eller säker socialinformation om smärtintensiteten på det kommande kallvattentestet. Efter densociala informationen utfördes två kategoriseringsuppgifter där de skulle angeom en bild föreställde något levande eller ett objekt, både före och underkallvattentestet, med ett överraskande minnestest 30 minuter efterkallvattentestet på de bilder som visades under kategoriseringsuppgiften. Detvar ingen skillnad på grupperna i osäkerheten om deras förväntan avkallvattentestet. Däremot förväntade sig den gruppen som fick osäkerinformation att kallvattentestet skulle vara smärtsammare än de som fick densäkra informationen. Vi hittade ingen skillnad mellan grupperna i varkensmärtupplevelsen eller minnet. Till sist, minnet försämrades för bilderna sompresenterades under kallvattentestet, oberoende av vilken grupptillhörighetdeltagarna hade. För att summera så stöddes ingen av våra hypoteser. Förslagför kommande forskning är att manipulera hur den sociala informationen gesför att göra det mer tydligt för deltagarna.

Integrerad rapportering (IR) sprider sig inom redovisningsvärlden och modellen ska enligt förespråkarna skänka en transparent bild över hur företagen sammanlänkar finansiell och icke-finansiell information. Genom intressent- och legitimitetsteoretiska postulat syftar studien till att visa vilka faktorer (storlek, skuldsättningsgrad, ägarkoncentration och bransch) som kan påverka valet att tillämpa IR-principer. Vidare undersöks om mängden integrerad information verkligen skiljer sig mellan företag som tillämpar IR och övriga. Fokus ligger på social- och miljöinformation som finns integrerad med övriga upplysningar.  Empirin har genererats genom en i huvudsak kvantitativ innehållsanalys av 67 årsredovisningar från företag noterade på Nasdaq OMX Large Cap. Regressionsanalyser och Mann-Whitney test har använts för att analysera den insamlade empirin.  De statistiska testerna visar att storlek och branschtillhörighet har signifikanta samband med mängden integrerad miljö- och social information i årsredovisningarna. Ägarkoncentration och skuldsättningsgrad visade dock inget samband vilket talar för att finansiella intressenter inte pressar företag mot IR-principer. Signifikanta skillnader kunde konstateras mellan årsredovisningarna som uppgavs vara integrerade i förhållande till övriga. Denna upptäckt kan tolkas som att IR-tillämpande företag även har en starkare hängivenhet till hållbarhetsfrågor.  Studien bidrar med en bild över hur IR-principer förekommer på svensk börs samt hur detta ur ett hållbarhetsperspektiv skiljer sig från övriga årsredovisningar. Vidare indikerar studien att paralleller kan dras mellan IR och frivillig rapportering i övrigt då företagens storlek och branschtillhörighet påverkat årsredovisningens utformning.  Som fortsatt forskning föreslås studier kring IR ur ett användarperspektiv då utbudet av detta idag är skralt och samtidigt kritiskt för fortsatt utveckling av IR. / Integrated reporting (IR) is spreading in the accounting world and according to proponents the model should give a transparent picture of how the companies are linking financial and non-financial disclosures. Through postulates from stakeholder- and legitimacy theory this study aims to demonstrate which factors (size, debt ratio, ownership concentration and industry) that may affect the choice of applying IR principles. Furthermore, the study also examines whether the amount of integrated information really differs between companies who allege to apply IR and others. Focus lays on social- and environmental information.  The empirical data is essentially generated by a quantitative content analysis of 67 annual reports from companies listed on Nasdaq OMX Large Cap. Regression analysis and Mann-Whitney tests were used to analyze the collected empirical data.  The statistical tests show that size and industry has significant effect on the amount of integrated information within the annual reports. Debt ratio and ownership concentration however, showed no relationship which leads to the conclusion that financial stakeholders is not pressuring the companies towards IR principles. Significant differences between the annual reports claimed to be integrated and other annual reports where observed. This finding could be interpreted as companies that apply IR also have a stronger devotion to sustainability issues.  Future research is suggested to be conducted from a user perspective. The supply of this type of studies is poor but crucial for continued development of IR.

Peer aggression and victimization are currently of national concern due to their high association with maladjustment. Moreover, peer aggression and victimization can occur as different forms (overt, relational) and functions (proactive, reactive), which are usually not examined within the same model. Peer aggression and victimization within the school context can be the result of individually developed negative social cognitions. These negative cognitions, based within social information processing theory, include outcome expectancies and values for pain and suffering. In addition, positive cognitions such as perceived social competence can decrease adverse outcomes such as peer aggression and victimization. This project seeks to take previous research and expand upon it in two ways: 1) examine overt, relational, proactive, and reactive aggression and victimization as separate constructs, within the same model, in association with outcome values, expectancies, and perceived social competence; and 2) examine the potential of extracurricular activities to serve as a buffer between maladjusted cognitions and aggression and victimization. In addition, this study will examine if these relationships differ by activity type, age and gender. Participants included 371 middle and high school students. Findings point toward the importance of examining the separate functions of aggression and victimization, as outcome values and expectancies are associated specifically with higher levels of proactive aggression and victimization and reactive aggression. Activity participation, particularly activities that are not associated with the school that the participant attends, seems to be serving as a buffer against maladjusted cognitions and functions of aggression and victimization. Specifically, having high efficacy for activity participation (ability to meet expectations within activity) serves a buffer for both reactive aggression and reactive victimization. Activity participation benefits appear to not be present if the individual is only participating because their parents are forcing them to be there. No group differences were found. These findings serve to demonstrate the importance of establishing fit of activity context for youth as well as their motivation for participation. More broadly, it is important to examine functions of aggression and victimization in the same model as the forms of aggression and victimization. By better understanding the moderating role of activities, schools can potentially have a low cost intervention tool for peer aggression and victimization difficulties.