Staying safe and visible via message sharing in online social networks

As an imperative channel for fast information propagation, online social networks (OSNs) also have their defects. One of them is the information leakage, i.e., information could be spread via OSNs to the users whom we are not willing to share with. Thus the problem of constructing a circle of trust to share information with as many friends as possible without further spreading it to unwanted targets has become a challenging research topic but still remained open. Our work is the first attempt to study the Maximum Circle of Trust problem seeking to share the information with the maximum expected number of poster’s friends such that the information spread to the unwanted targets is brought to its knees. First, we consider a special and more practical case with the two-hop information propagation and a single unwanted target. In this case, we show that this problem is NP-hard, which denies the existence of an exact polynomial-time algorithm. We thus propose a Fully Polynomial-Time Approximation Scheme (FPTAS), which can not only adjust any allowable performance error bound but also run in polynomial time with both the input size and allowed error. FPTAS is the best approximation solution one can ever wish for an NP-hard problem. We next consider the number of unwanted targets is bounded and prove that there does not exist an FPTAS in this case. Instead, we design a Polynomial-Time Approximation Scheme (PTAS) in which the allowable error can also be controlled. When the number of unwanted targets are not bounded, we provide a randomized algorithm, along with the analytical theoretical bound and inapproximaibility result. Finally, we consider a general case with many hops information propagation and further show its #P-hardness and propose an effective Iterative Circle of Trust Detection (ICTD) algorithm based on a novel greedy function. An extensive experiment on various real-world OSNs has validated the effectiveness of our proposed approximation and ICTD algorithms. Such an extensive experiment also highlights several important observations on information leakage which help to sharpen the security of OSNs in the future.     

Likelihood and higher-order approximations to tail areas: A review and annotated bibliography

Recent developments in higher-order asymptotic theory for statistical inference have emphasized the fundamental role of the likelihood function in providing accurate approximations to cumulative distribution functions. This paper summarizes the main results, with an emphasis on classes of problems for which relatively easily implemented solutions exist. A survey of the literature indicates the large number of problems solved and solvable by this method. Generalizations and extensions, with suggestions for further development, are considered.     

Differential impact of Web site content: Exploring the influence of source (public relations versus news), modality,and participation on college students’ perceptions

This experiment examined the impact of source, modality, and participation on perceptions of credibility, salience, attitudes, and general Web site evaluation. The data showed no significant differences between online stories coming from either public relations or news sources on any of the study's dependent variables. However, significant differences did emerge for the effects of multimedia and audience engagement.     

The Effect of Gender Context on Children's Social Behavior in a Limited Resource Situation: An Observational Study

Knowing when to compete and when to cooperate to maximize opportunities for equal access to activities and materials in groups is critical to children's social and cognitive development. The present study examined the individual (gender, social competence) and contextual factors (gender context) that may determine why some children are more successful than others. One hundred and fifty‐six children (M age=6.5 years) were divided into 39 groups of four and videotaped while engaged in a task that required them to cooperate in order to view cartoons. Children within all groups were unfamiliar to one another. Groups varied in gender composition (all girls, all boys, or mixed‐sex) and social competence (high vs. low). Group composition by gender interaction effects were found. Girls were most successful at gaining viewing time in same‐sex groups, and least successful in mixed‐sex groups. Conversely, boys were least successful in same‐sex groups and most successful in mixed‐sex groups. Similar results were also found at the group level of analysis; however, the way in which the resources were distributed differed as a function of group type. Same‐sex girl groups were inequitable but efficient whereas same‐sex boy groups were more equitable than mixed groups but inefficient compared to same‐sex girl groups. Social competence did not influence children's behavior. The findings from the present study highlight the effect of gender context on cooperation and competition and the relevance of adopting an unfamiliar peer paradigm when investigating children's social behavior.     

Personal heroes,religion, and transcendental metanarratives

With the increased sociological interest in popular culture, many studies have examined the hero types lauded by the media from situation comedies to movies, books, and magazines. Few studies, however, have examined who, if anybody, actual individuals identify as personal heroes. To the extent that the hero identification of individuals has been examined at all, it has generally been the hero identification of children and adolescents that has been studied. The study of heroes is important because heroes are one indicator of who we are and what we stand for. That is partly what motivates the recent attention to the media's identification of heroes. Yet while the media represent a very visible aspect of culture, who individuals privately cite as their heroes is, although less visible, just as much a part of who we are as a culture. Accordingly, this paper reports on findings from two telephone surveys conducted in Philadelphia that, among other questions pertaining to the meaning of life, asked adults over 18 whether they had any heroes and if so who those heroes were. The tendency to identify with heroes was found to be related to transcendental concerns with the meaning of life and to religiosity. Overall, the pattern of findings discloses an unstudied dimension of cultural disenchantment.     

Demographic Foundations of Political Empowerment in Multiminority Cities

As U.S. cities accommodate increasing ethnic and racial diversity, political choices may unify or divide their local populations. Those choices pull communities toward two different modes of pluralism: traditional “melting pot” assimilation or a complex mosaic of racial and ethnic assertiveness. Central to this issue is equity and empowerment, which may be accentuated by minority populations’ size, structure, and spatial concentration. We examine two potential modes of local empowerment: “dominance,” whereby each group is the majority of voters in single election districts (reinforcing separative tendencies), and “influence,” whereby a group gains “influential minority” status in several districts (reinforcing unifying tendencies).