Asynchronous Learning Networks (ALNs) make the process of collaboration more transparent, because a transcript of conference messages can be used to assess individual roles and contributions and the collaborative process itself. This study considers three aspects of ALNs: the design; the quality of the resulting knowledge construction process; and cohesion, role and power network structures. The design is evaluated according to the Social Interdependence Theory of Cooperative Learning. The quality of the knowledge construction process is evaluated through Content Analysis; and the network structures are analyzed using Social Network Analysis of the response relations among participants during online discussions. In this research we analyze data from two three-monthlong ALN academic university courses: a formal, structured, closed forum and an informal, nonstructured, open forum. We found that in the structured ALN, the knowledge construction process reached a very high phase of critical thinking and developed cohesive cliques. The students took on bridging and triggering roles, while the tutor had relatively little power. In the non-structured ALN, the knowledge construction process reached a low phase of cognitive activity; few cliques were constructed; most of the students took on the passive role of teacher-followers; and the tutor was at the center of activity. These differences are statistically significant. We conclude that a well-designed ALN develops significant, distinct cohesion, and role and power structures lead the knowledge construction process to high phases of critical thinking.

Asynchronous Learning Networks (ALNs) make the process of collaboration more transparent, because a transcript of conference messages can be used to assess individual roles and contributions and the collaborative process itself. This study considers three aspects of ALNs: the design; the quality of the resulting knowledge construction process; and cohesion, role and power network structures. The design is evaluated according to the Social Interdependence Theory of Cooperative Learning. The quality of the knowledge construction process is evaluated through Content Analysis; and the network structures are analyzed using Social Network Analysis of the response relations among participants during online discussions. In this research we analyze data from two three-month-long ALN academic university courses: a formal, structured, closed forum and an informal, non-structured, open forum. We found that in the structured ALN, the knowledge construction process reached a very high phase of critical thinking and developed cohesive cliques. The students took on bridging and triggering roles, while the tutor had relatively little power. In the non-structured ALN, the knowledge construction process reached a low phase of cognitive activity; few cliques were constructed; most of the students took on the passive role of teacher-followers; and the tutor was at the center of activity. These differences are statistically significant. We conclude that a well-designed ALN develops significant, distinct cohesion, and role and power structures lead the knowledge construction process to high phases of critical thinking.

Cloud-to-ground lightning flashes usually consist of one or several strokes coming in very short temporal succession and close spatial proximity. A commonly used method for converting stroke data into flashes is using the National Lightning Detection Network (NLDN) thresholds of maximum temporal separation of 0.5 s and maximum lateral distance of 10 km radius between successive strokes. In the present study, we tested a location-based algorithm with several spatial and temporal ranges, and analyzed stroke data obtained by the Israel Lightning Location System (ILLS) during one year (1.8.2009–31.7.2010). We computed the multiplicity, the percentage of single stroke flashes and the geographical distribution of average multiplicity values for thunderstorms in the Eastern Mediterranean region. Results show that for the NLDN thresholds, the percentage of single stroke flashes in Israel was 37% and the average multiplicity was 1.7. We reanalyzed the data with a spatial range that equals twice the ILLS location error and shorter times. For the new thresholds of maximum distance of 2.5 km and maximum allowed temporal separation of 0.2 s we find that the mean multiplicity of negative CGs is lowered to 1.4 and find a percentage of 58% of single stroke flashes. A unique severe storm from 30 October 2009 is analyzed and compared with the annual average of 2009/2010, showing that large deviations from the mean values can occur in specific events.

The discharges of lightning flashes in different, physically separate, convective cells are traditionally considered to be a memory-less system of stochastic, independent events as the electric field within any individual cell exceeds the local breakdown threshold. The present work offers additional insight into the properties of the network of thunderstorm cells, suggested to be mutually coupled and synchronized by Yair et al. (2006, 2009). We analyzed lightning data from a storm that occurred on 30.10.2009 in the eastern Mediterranean, which produced over 20,000 cloud-to-ground flashes in less than 20 hours, registered by the LPATS operated by the Israeli Electrical Company. Each half-hour of the storm was separately analyzed. Clustering algorithms revealed geographically packed active cells, thus enabling us to assign each flash to a cell. We analyzed pairs of subsequent flashes. We show that the consecutive cells are probabilistically interdependent – when the network is up to creating a flash in a new cell, it remembers the cell of the previous flash. Furthermore, the inter-arrival time between flashes occurring in same cell follow a highly skewed, nonexponential distribution, which means that the network remember the elapsed time. Finally, there is an inverse relation between the interdependence level in the network, quantified by its mutual information, and the median of that inter-arrival time distribution of flashes within the same cell; higher levels of interdependence decrease the median down to a certain lower bound. That is, the interactions between the cells in the network accelerate the creation of flashes within cells, up to a critical limit, which represents the minimal charging time in clouds.

With the rapid growth of mobile devices and networked systems and applications, the demand for effective computer security is increasing. Our security is challenged increasingly by non-traditional threats from adversaries, from hostile regimes and international criminals and terrorists, who use new ways of attack by exploring new technologies and the world’s increasing openness (Bosch, 2012). Thus, it is essential to devise security strategies to prevent cyber attacks on critical infrastructures and other essential information systems. Most computer systems are protected through a process of user identification and authentication. While identification is usually non-private information provided by users to identify themselves and can be known to system administrators and other system users, authentication is any protocol or process that permits one entity to establish the identity of another entity. The world of information technology offers a multitude of approaches and techniques, from knowledge-based authentication like passwords to biometrics-based authentication like physical fingerprints or touch screen tapping behavior (Erlich & Zviran, 2009). As mobile devices and smartphones become more widely used, receive regular data transitions from desktop systems and store increasing amounts of sensitive information, the imperative of ensuring their data security has become a major challenge. The ultimate goal for mobile devices is to provide the appropriate level of security and protection in a manner that the user can understand and use (Botha, Furnell, & Clarke, 2009). This article reviews the three main approaches to user authentication: knowledge-based, possessionbased and biometrics-based. BACKGROUND

With the rapid growth of information systems and networks, security is a major concern of organizations. The main goals of information systems security are confidentially, integrity, and availability. The cornerstone of an organization’s security lies in designing, developing and implementing proper information systems’ security policy that balances security goals with the organization’s needs. In this paper, the authors discuss the goals of information systems security and the techniques to achieve them. Specifically, the paper focuses on access control and the various authentication approaches, as well as intrusion detection and prevention systems. As attacks become more frequent and devastating, ongoing research is required to adapt and improve security technologies and policies to reflect new modes of attack to keep information systems secure.

To assess the CT features of sealed rupture of abdominal aortic aneurysm.

The development and emergence of new technologies in distance learning has opened a broad range of options for promoting learning. New technologies and the latest generation of Web-based tools have been increasingly adopted in distance learning. Integrating these technologies into education has a profound impact on all areas of learning, from course management to problem-solving instruction. The new technologies have provided a valuable addition to interactivity and interactions in the process of teaching and learning. In recent years, there has been a rapid increase in the use of the latest generation of Web-based tools (Web 2.0), such as wikis, blogs, and podcasts, in distance learning. The possibilities of wikis and blogs and other new Web tools are countless. Any topic that needs to be discussed openly, quickly, or in a collaborative manner can benefit from these tools.

With the rapid growth of networked systems and applications such as e-commerce, the demand for effective computer security is increasing. Most computer systems are protected through a process of user identification and authentication. While identification is usually non-private information provided by users to identify themselves and can be known by system administrators and other system users, authentication provides secret, private user information which can authenticate their identity. There are various authentication approaches and techniques, from passwords to public keys (Smith, 2002). This article presents the three main authentication approaches, their technology and implementation issues, and the factors to be considered when choosing an authentication method.

The philosophy underlying open source software (OSS) is enabling programmers to freely access the software source by distributing the software source code, thus allowing them to use the software for any purpose, to adapt and modify it, and redistribute the original or the modified source for further use, modification, and redistribution. The modifications, which include fixing bugs and improving the source, evolve the software. This evolutionary process can produce better software than the traditional proprietary software, in which the source is open only to a very few programmers and is closed to everybody else who blindly use it but cannot change or modify it. The idea of open source software arose about 20 years ago and in recent years is breaking out into the educational, commercial, and governmental world. It offers many opportunities when implemented appropriately. The chapter will present a detailed definition of open source software, its philosophy, its operating principles and rules, and its strengths and weaknesses in comparison to proprietary software. A better understanding of the philosophy underlying open source software will motivate programmers to utilize the opportunities it offers and implement it appropriately.

Studies indicate that the use of technologies as teaching aids and tools for self-study is influenced by students' attitudes toward computers and their applications. The purpose of this study is to determine whether taking a Computer Literacy and Applications (CLA) course has an impact on students' attitudes toward computer applications, across various undergraduate disciplines. A Computer Application Attitude (CAA) questionnaire was administered at the beginning and at the end of the semester to social science students enrolled in a CLA course. The study population was divided into two groups according to the students' field of study: quantitative-oriented and qualitative-oriented. A significant difference was found in attitudes before and after the CLA course only in the quantitative group. Based upon the results of this study, it is recommended to offer different computer literacy courses to the different groups to improve students' attitudes toward the use of these applications.

The goal of this research is to explore the nature of the response relation in online learning networks. We ask whether actors choose their response partners at random or whether certain special mechanisms are at work. We compare the observed values of clustering of responses in 95 online learning networks with the predictions of two suitable Random Graph models. All the online distance learning networks exhibit clustering that is incompatible with the random choices of response partners, with no constraints on the response capacities of actors. But the observed clustering in all networks is compatible with the random choices of response partners subject to constraints on their total response capacities. We provide a possible explanation for this behavior, based on the nature and goal of the online learning networks, and discuss the practical implications for online distance education.

The philosophy underlying open source software (OSS) is enabling programmers to freely access the software source by distributing the software source code, thus allowing them to use the software for any purpose, to adapt and modify it, and redistribute the original or the modified source for further use, modification, and redistribution. The modifications, which include fixing bugs and improving the source, evolve the software. This evolutionary process can produce better software than the traditional proprietary software, in which the source is open only to a very few programmers and is closed to everybody else who blindly use it but cannot change or modify it. The idea of open source software arose about 20 years ago and in recent years is breaking out into the educational, commercial, and governmental world. It offers many opportunities when implemented appropriately. The chapter will present a detailed definition of open source software, its philosophy, its operating principles and rules, and its strengths and weaknesses in comparison to proprietary software. A better understanding of the philosophy underlying open source software will motivate programmers to utilize the opportunities it offers and implement it appropriately.

Computer-based information systems in general, and Internet e-commerce and e-business systems in particular, employ many types of resources that need to be protected against access by unauthorized users. Three main components of access control are used in most information systems: identification, authentication, and authorization. In this paper we focus on authentication, which is the most problematic component. The three main approaches to user authentication are: knowledge-based, possession-based, and biometric-based. We review and compare the various authentication mechanisms of these approaches and the technology and implementation issues they involve.Our conclusion is that there is no silver bullet solution to user authentication problems. Authentication practices need improvement. Further research should lead to a better understanding of user behavior and the applied psychology aspects of computer security.

The development of new communication technologies and their applications has opened a broad spectrum of options to promote learning, of which a significant one is CMC – Computer-Mediated Communication. Yet, students use this medium to a relatively small extent. Our premise is that the use of these technologies depends on the level of skills and expertise of the individuals using them. The purpose of this study is to determine whether taking a Computer Literacy and Applications course (CLA) before taking CMC courses has an impact on students' participation in CMC courses and on the effective use of various CMC tools. The sample consisted of 153 students enrolled in CMC courses in the Social Sciences in the Spring 2001/2 and Fall 2002/3 semesters. Participants were divided into two groups: 80 students who had taken CLA, and 73 students who had not. A questionnaire to assess the impact of CLA on participation in CMC courses was administered to the two groups. The results of the study indicate that participation in CMC courses is more intensive in the group that had taken CLA. Based on these findings, we recommend mandating a CLA course, like the one developed at the Open University of Israel (OUI), before taking CMC courses.

The development of new communication technologies has opened a broad range of options for promoting learning, of which a significant one is CMC—computer-mediated communication. CMC refers to communication that utilizes a combination of telecommunication technologies and computer networks, and enables users to transmit, store, and receive information using synchronous and asynchronous tools.

Theoretical foundation of Response mechanisms in networks of online learners are revealed by Statistical Analysis of p* Markov Models for the Networks. Our comparative analysis of two networks shows that the minimal-effort hunt-for-social-capital mechanism controls a major behavior of both networks: negative tendency to respond. Differences in designs of the networks enhance certain mechanisms while suppressing others: cognition balance, predicted by the theories of cognitive balance, and peer pressure, predicted by the theories of collective action are enhanced in a team like network but suppressed in a Q&A like forum. On the other hand, exchange mechanism, predicted by the theory of exchange & resource dependency and tutor’s responsibility mechanism are enhanced in the Q&A type forum but suppressed in the team like network. Contagion mechanism, predicted by the theory of collective action did not develop in both networks. The different mechanisms lead to the formation of different micro and macro structures in the topologies of the responses of the networks and hence in the buildup of collaborative knowledge. The techniques presented in this work can be extended to other types of mechanisms and networks.

Online communities are described in terms of collections of virtual neighborhoods, each of which is a subset of interdependent members. The significant virtual neighborhoods are revealed by fitting parametric Markov field models (p*) to the response relations of the communities. The underlying theoretical mechanisms are then deduced by matching the revealed virtual neighborhoods with the predictions of network emergence theories. We demonstrate that the underlying mechanisms are related to specific design features of the communities. This method can be extended to other relations in online communities and to longitudinal analysis, and applied to real-time monitoring of online communications.

We outline and evaluate a binary-positive clustering model. It is based on a binary representation of data records in rows where column entries, either ‘1’ or ‘0’, correspond to all possible data values that tributes may take. A new group similarity index (GSI) is devised which takes into account only the positive attributes as basis for the grouping and clustering algorithm. The model is compared with standard clustering models. For the comparison we define an objective measure about two similarity factors: within-class similarity (WCS) and between-class similarity (BCS), seeking a maximum intra-group and minimum inter-group proximity, respectively. A coefficient of variation (CV) statistic is then employed to combine the two factors into a measure of relative diversity between records and groups. When applied to a common data set our binary clustering shows significant advantages over standard clustering models.