The Pan American (2007-06-14)

https://scholarworks.utrgv.edu/panamerican/1732/thumbnail.jp

Enhancing multi-source content delivery in content-centric networks with fountain coding

Fountain coding has been considered as especially suitable for lossy environments, such as wireless networks, as it provides redundancy while reducing coordination overheads between sender(s) and receiver(s). As such it presents beneficial properties for multi-source and/or multicast communication. In this paper we investigate enhancing/increasing multi-source content delivery efficiency in the context of Content-Centric Networking (CCN) with the usage of fountain codes. In particular, we examine whether the combination of fountain coding with the in-network caching capabilities of CCN can further improve performance. We also present an enhancement of CCN's Interest forwarding mechanism that aims at minimizing duplicate transmissions that may occur in a multi-source transmission scenario, where all available content providers and caches with matching (cached) content transmit data packets simultaneously. Our simulations indicate that the use of fountain coding in CCN is a valid approach that further increases network performance compared to traditional schemes

Bilingual preschool education: a comparative study between Hong Kong and Shanghai

Global and local factors have recently pushed English-Chinese bilingualism to the forefront of early childhood education in Hong Kong and Shanghai. Signaling new sociolinguístic alignments, each city is pursuing language policies according to its own political and economic imperatives. Using Bronfenbrenner’s (1977) ecological system's theory as a framework for analysis, this research study examines the contextual layers that shape the linguistic environments of the two cities, focusing on the macrosystem’s forces of globalization, the exosystem’s social networks, the mesosystem's institutions and human players, the microsystem's schools and homes, and the chronosystem’s biology, acknowledging all factors that affect child development. In the hope of providing better strategies and interventions for developing second language learning, it looks at the stakeholders' attitudes towards, beliefs about, and expectations of English, as well as at parental involvement in children’s English education, perceptions about NETs (native English-speaking teachers), and curriculum implementation. Quantitative and qualitative data collected (from four schools in each city and a total of 438 respondents) through questionnaires, interviews and archival documents are then triangulated to identify differences and similarities between the two cities. The results show that English is universally promoted for its economic benefits, both to individuals and society. The form of preschool bilingualism advocated by the governments of Hong Kong and Shanghai, however, is unduly influenced by political and nationalist considerations. This has lead in Shanghai to conceptualizations of bilingualism that allow only for the acquisition of English without its attendant cultural and philosophical dimensions. In Hong Kong, the government's attempt to arbitrarily reduce the size of English-medium education, has lead, due to blowback, to extremely high English literacy expectations for preschoolers, delivered through overly ambitious programmes. In both cities, attempts to safeguard the use of the mother tongue as the primary medium of Instruction stand in the way of early bilingual development through immersion or partial immersion. In addition, the stakeholders' disparate expectations about when, how and why English at preschool is important have given rise to conflicts and dilemmas that distort the two cities' cultures of learning and the extent and form of their education reforms. The recommendations made seek to create for bilingual preschool education, sufficient space, given the current political, social, and economic conditions in both cities, to allow educators to pursue it with the most effective pedagogies

A Conceptual Model for the Development of a National Cybersecurity Index: An Integrated Framework

As ICT and cyberspace become sources of impressive innovation, the reliance of organizations, governments, and people on them will increase. However, with this vast reliance, hazardous vulnerabilities have emerged. These vulnerabilities may be exploited, resulting in information and cybersecurity issues at the national as well as the international levels. Cybersecurity is critical for sustaining resilience in critical infrastructures (CI) as well as information infrastructures (CII). Accordingly, cybersecurity should be incorporated into the economic and national security model of a nation. With this in mind, a cybersecurity index is a necessary tool to compare the performance of nations in terms of cybersecurity initiatives, and in articulating effective cybersecurity policies and strategies. This paper proposes a holistic framework for building a cybersecurity index taking into consideration the technological, legal, economic, cultural, and international relations factors pertinent to countries and paves the way for cybersecurity measures and metrics to be established and tested

In-network cache management and resource allocation for information-centric networks

We introduce the concept of resource management for in-network caching environments. We argue that in Information-Centric Networking environments, deterministically caching content messages at predefined places along the content delivery path results in unfair and inefficient content multiplexing between different content flows, as well as in significant caching redundancy. Instead, allocating resources along the path according to content flow characteristics results in better use of network resources and therefore, higher overall performance. The design principles of our proposed in-network caching scheme, which we call ProbCache, target these two outcomes, namely reduction of caching redundancy and fair content flow multiplexing along the delivery path. In particular, ProbCache approximates the caching capability of a path and caches contents probabilistically to: 1) leave caching space for other flows sharing (part of) the same path, and 2) fairly multiplex contents in caches along the path from the server to the client. We elaborate on the content multiplexing fairness of ProbCache and find that it sometimes behaves in favor of content flows connected far away from the source, that is, it gives higher priority to flows travelling longer paths, leaving little space to shorter-path flows. We introduce an enhanced version of the main algorithm that guarantees fair behavior to all participating content flows. We evaluate the proposed schemes in both homogeneous and heterogeneous cache size environments and formulate a framework for resource allocation in in-network caching environments. The proposed probabilistic approach to in-network caching exhibits ideal performance both in terms of network resource utilization and in terms of resource allocation fairness among competing content flows. Finally, and in contrast to the expected behavior, we find that the efficient design of ProbCache results in fast convergence to caching of popular content items