Using OGRO and CertiVeR to improve OCSP validation for Grids

Authentication and authorization in many distributed systems rely on the use of cryptographic credentials that in most of the cases have a defined lifetime. This feature mandates the use of mechanisms able to determine whether a particular credential can be trusted at a given moment. This process is commonly named validation. Among available validation mechanisms, the Online Certificate Status Protocol (OCSP) stands out due to its ability to carry near real time certificate status information. Despite its importance for security, OCSP faces considerable challenges in the computational Grid (i.e. Proxy Certificate’s validation) that are being studied at the Global Grid Forum’s CA Operations Work Group (CAOPS-WG). As members of this group, we have implemented an OCSP validation infrastructure for the Globus Toolkit 4, composed of the CertiVeR Validation Service and our Open GRid Ocsp (OGRO) client library, which introduced the Grid Validation Policy. This paper summarizes our experiences on that work and the results obtained up to now. Furthermore we introduce the prevalidation concept, a mechanism analogous to the Authorization Push-Model, capable of improving OCSP validation performance in Grids. This paper also reports the results obtained with OGRO’s prevalidation rules for Grid Services as a proof of concept.

Real time 3D face and facial feature tracking

Detecting and tracking human faces in video sequences is useful in a number of applications such as gesture recognition and human-machine interaction. In this paper, we show that online appearance models (holistic approaches) can be used for simultaneously tracking the head, the lips, the eyebrows, and the eyelids in monocular video sequences. Unlike previous approaches to eyelid tracking, we show that the online appearance models can be used for this purpose. Neither color information nor intensity edges are used by our proposed approach. More precisely, we show how the classical appearance-based trackers can be upgraded in order to deal with fast eyelid movements. The proposed eyelid tracking is made robust by avoiding eye feature extraction. Experiments on real videos show the usefulness of the proposed tracking schemes as well as their enhancement to our previous approach.

Competitive exploration of rectilinear polygons

Exploring a polygon with robots when the robots do not have knowledge of the surroundings can be viewed as an online problem. Typical for online problems is that decisions must be made based on past events without complete information about the future. In our case the robots do not have complete information about the environment. Competitive analysis can be used to measure the performance of methods solving online problems. The competitive ratio of such a method is the ratio between the method's performance and the performance of the best method having full knowledge of the future. We prove constant competitive strategies and lower bounds for exploring a simple rectilinear polygon in the _L1$L_1$ metric.     

Higher education scholars' participation and practices on Twitter

Scholars participate in online social networks for professional purposes. In such networks, learning takes the form of participation and identity formation through engagement in and contribution to networked practices. While current literature describes the possible benefits of online participation, empirical research on scholars' use of online social networks in the educational technology literature is negligible. The purpose of this paper is to understand scholars' naturalistic practices in social networks in general, and on Twitter in particular. Tweets from 45 scholars were analysed qualitatively to arrive at dominant themes describing online social network practice. Findings indicate that scholars participating on Twitter (1) shared information, resources, and media relating to their professional practice; (2) shared information about their classroom and their students; (3) requested assistance from and offered suggestions to others; (4) engaged in social commentary; (5) engaged in digital identity and impression management; (6) sought to network and make connections with others; and (7) highlighted their participation in online networks other than Twitter. These findings assist the field in understanding the emerging practice of scholarly participation in online networks.     

Attitudes of college students enrolled in 2-year health care programs towards online learning

Colleges offering 2-year diplomas to high-school graduates were among the forefront leaders in online learning however studies illustrating appropriate course construction for such student populations are scarce. Pharmacy Math (MATH16532) is a core course for students enrolled in the Practical Nursing (PN) and Pharmacy Technician (PT) programs at Sheridan Institute. PT and PN students enrolled in MATH16532 during their first term were surveyed to determine student attitudes and skills gained from participating in an online course. Students were then followed up during their second term studies to determine transferability of skills gained. Initially, students did not exhibit a positive attitude towards the online version of Math16532. Participation in the online version of MATH16532 however allowed students to enhance their written ability and critical appraisal skills, gain time management skills, and become independent learners. PT and PN students preferred an orientation session at the beginning of the course and a well organized, easy-to-navigate course. Even though considered as predominantly digital native students, both student groups remained anxious throughout the course regarding the online delivery and preferred a hybrid mode of delivery. Despite the initial resistance to an online math course, students indicated that they would retake the course again in an online format towards the end of the course and there appeared to be a trend to enrol in another online course. Several recommendations regarding the design and construct of online courses in a 2-year college program are provided to facilitate acceptance of online learning for students enrolled in such programs.     

The world’s most intense online gaming culture: Addiction and high-engagement prevalence rates among South Korean adolescents and young adults

Failure to establish agreed-upon criteria by which to measure and identify online video game addiction has resulted in a lack of reliable evidence of the actual percentage of individuals who are pathologically dependent. Building upon prior research, the present study sought to better determine the magnitude of pathological online video game play using a distinction between core and peripheral criteria for behavioral addiction. Preferences and perceptions towards online video games and addiction were also examined to better understand players’ habits. A questionnaire was administered to 1332 South Korean students across 11 high schools and 1 middle school in an area surrounding the capital of Seoul. Using a monothetic and a polythetic classification system, findings showed rates ranging between 1.7% and 25.5%, with a 2.7% addiction rate when distinguishing core from peripheral criteria. These results may suggest that online video game addiction rates in intense gaming cultures such as South Korea are not as high as otherwise believed. The findings will be of assistance to educators, policymakers, clinicians, and researchers in understanding the challenges in deriving meaningful video game addiction prevalence rates, and thus being able to better separate reality from conjecture with regard to the notion of pathological game play.     

The effect of moderator’s facilitative strategies on online synchronous discussions

Moderators play an important role within a computer supported collaborative learning environment, and thus facilitative strategies and communication technology are nowadays used to enhance students’ learning. This study proposed facilitative strategies as a guide for students’ learning, and explored the influence of these strategies on the students’ online synchronous discussion. A total of 331 senior high school students from eight computer classes in northern Taiwan were recruited to participate in this study. They were randomly assigned into an experimental condition, with the moderators’ facilitation to complete online learning tasks, and the control condition without moderators’ support. To fulfill the goal of the research, four strategies—helping students focus on the main topic, facilitating students’ making argumentation, giving students positive feedback, and helping students sustain threaded discussion—were adopted to facilitate the online synchronous discussion in the experimental condition. According to the results of the content analysis, four group discussion patterns were revealed, including collaboration, centralization, partial contribution, and non-interaction. The findings suggest that the moderator helped enhance the collaboration pattern and increase the online participation rate. In addition, it was found that the strategies of helping students focus on the main topic and giving students positive feedback were frequently employed.     

Predicting social cues during online discussions: Effects of evaluations and knowledge content

This study examined whether evaluations (agreements, disagreements), knowledge content (new ideas, justifications), or social cues (SCs) in recent messages affected a current message’s positive or negative SC during asynchronous, online discussions. Using statistical discourse analysis, we modeled 894 messages by 183 participants on 60 high school mathematics topics (typically eight people posted per topic) on a mathematics problem solving website not connected to any class or school. Results showed that recent agreements increased the likelihood of positive SC, whereas justifications reduced it. Disagreements increased the likelihood of negative SC, whereas new ideas reduced it. Meanwhile, recent positive or negative SCs did not affect the likelihood of a subsequent SC. Together, these results suggest that judicious use of positive SCs rather than negative SCs during disagreements can help students both construct knowledge and maintain social relationships.     

The role of self-construal in consumers’ electronic word of mouth (eWOM) in social networking sites: A social cognitive approach

The current study reconceptualized self-construal as a social cognitive indicator of self-observation that individuals employ for developing and maintaining social relationship with others. From the social cognitive perspective, this study investigated how consumers’ self-construal can affect consumers’ electronic word of mouth (eWOM) behavior through two cognitive factors (online community engagement self-efficacy and social outcome expectations) in the context of a social networking site. This study conducted an online experiment that directed 160 participants to visit a newly created online community. The results demonstrated that consumers’ relational view became salient when the consumers’ self-construal was primed to be interdependent rather than independent. Further, the results showed that such interdependent self-construal positively influenced consumers’ eWOM behavioral intentions through their community engagement self-efficacy and their social outcome expectations.