1522 research outputs found
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Performance Implications of IPSec Deployment
Get PDFVirtual Private Networks (VPNs) use the Internet or other data network service as a backbone to provide a secure connection across a potentially hostile WAN. Such security guarantees provide the motivation for VPN deployment. This security does, however, come at a performance cost brought about by the increased processing overhead. This paper presents an investigation into these overheads. In particular, this investigation will consider different user resource availability in addition to router type and encryption algorithms
Adapting access rights to the changing profile of user sets present in a ubicomp environment : progression and therapeutic approaches
No full textMacular Pigment and Percentage of Body Fat.
Get PDFPurpose. To Investigate the relationship between percentage of body fat and macular pigment (MP) optical density.
Methods. One hundred healthy subjects of ages between 22 and 60 years volunteered to participate in this study. MP optical density was measured psychophysically, serum lutein and zeaxanthin were quantified by HPLC, and dietary intake of lutein and zeaxanthin was assessed using a validated food frequency questionnaire. Body fat was measured by dual energy x-ray absorptiometry (DEXA); body mass index (BMI) was also calculated fro each subject. Clinical and personal details were recorded, with particular attention directed towards putative risk factors for AMD
Experimental Investigation of a Bistable System in the Presence of Noise and Delay
No full textWe experimentally analyze the behavior of a non-Markovian bistable system with noise, using a vertical cavity surface emitting laser with time-delayed optoelectronic feedback. The effects of the delayed feedback are observed in the probability distribution of the residence times of the two orthogonal polarization states, and in the polarization-resolved power spectrum. They agree well with recent theoretical predictions based on a two-state model with transition rates depending on an earlier state of the system. We also observe experimentally and explain theoretically that the residence time probability distribution deviates from exponential decay for residence times close to (and smaller than) the delay time
Infrastructure Requirements for Smart Spaces and Managed Zones
No full textThis paper discusses the underlying infrastructural
requirements for Smart Spaces and Managed
Zones. The focus is on generic technologies rather
than specific solution to specific problems. At a
political ownership level, who owns the
infrastructure is key. This paper addresses the
issues of Open Access Networks (OANs) with
pointers to the issues they raise. Such networks
allow the reuse of a single underlying
infrastructure for multiple purposes, allowing
logically distinct smart spaces to overlay each other
in a single physical wireless or fixed IP-based
network. At the network protocol level, one key
assumption is that smart space infrastructures are
based on the Internet Protocol (IPv4, IPv6). This
paper will argue that, for mobile devices, IPv6 is
the obvious choice. The reasons include the
available address range for a large proliferation of
devices, the ability to allow p2p (peer-to-peer)
interactions and lightweight services end-to-end
across such IPv6 networks, the ability to allow
auto-configuration (allowing flexible lightweight
management), and the ability to support redirection
of traffic to new locations (mobile IPv6).
[The M-Zones research programme has been
funded by the Irish Higher Education Authority,
PRTLI Cycle 3
Feedback induced polarisation switching in vertical cavity surface emitting lasers
Get PDFWe analyse the behaviour of a bistable vertical cavity semiconductor laser under the influence of optical feedback.
Without feedback, this laser emits either vertically or horizontally polarised light with a region where polarisation
bistability is observed. In this paper, we show that weak optical feedback can induce polarisation switching regardless
of the polarisation of the re-injected light. These switches are quite similar to those observed in the current noise induced
case. However, remarkable differences appear in the probability distribution of switching times depending on the
polarisation state of the re-injected light. Experimental results detailing these differences are presented and the possible
contributing mechanisms discussed
A portrait of OLAS as a young information literacy tutorial
Get PDFThis article begins with an analysis of the Information Society, discussing its repercussions and defining the term, information literacy. It also describes the need for, as well as the creation and development of, an online information literacy tutorial, named OLAS* at Waterford Institute of Technology Libraries. OLAS follows international best practice and its overall framework is based on US, Australian and UK information literacy models, while its learning outcomes follow those produced both by CAUL and Peter Godwin, South Bank University, London. OLAS aims to introduce basic and advanced concepts of information literacy to the broadest possible range of learners both on-campus and remotely. Dewald’s (1999) characteristics of good library instruction form the basis of its pedagogy. OLAS is currently being piloted at WIT. It is freely available from WIT Libraries’ website, apart from the integrated commercial database product to which access is contractually limited to WIT students & staff. Further development is focussed on building an improved version of the course in the WebCT virtual learning environment. The WebCT version will include more richly interactive content, will facilitate credited assessment of WIT registered students, and will address outstanding accessibility issues
Integration, Isolation and IT Education for an improved Architecture Engineering and Construction (AEC) Industry
Get PDFThis paper concerns the IT Education of Architecture Engineering and Construction (AEC) professionals. It reflects on the relationship between these professionals and how the AEC Industry should change for the better of all stakeholders.
These changes include a greater and improved use of IT, but the implementation of such changes has been disappointingly slow. Central to the associated complications are the difficulties in integrating a variety of people, processes and technologies.
The creation of separate professional groupings within the AEC Industry over the past centuries and the associated ‘traditional’ working processes has had some benefits, but it has hindered integration. The majority of AEC education, including that relating to IT and particularly at undergraduate level, continues to be carried out in isolation.
The discussions in this paper include reference to the author’s personal experience on interdisciplinary programmes and in the activities of the Construction IT Alliance (CITA). It concludes that if the AEC Industry is to make faster progress towards harnessing the true potential of IT, the education of the different professionals at all levels should be carried out in a more proactive and integrated manner
Addressing Fraud Detection and Management in Next-Generation Telecommunications Networks
No full textThis paper examines the problem of detecting and managing fraud in next-generation telecommunications networks and presents work in progress on implementing a rules-based fraud detection system. The motivations for committing fraud and the different types of fraud that can be perpetrated in next generation networks are examined. The fraud detection system provides an interface that allows users to enter rules that describe possible fraud scenarios. If a rule proves true, an alert is raised indicating that the analyzed record warrants more attention. Features of the system include the use of flexible data formats, spreadsheet based rules specification and the deployment of data reduction techniques to efficiently profile user behavior
