Adaptive optical networks using photorefractive crystals

The capabilities of photorefractive crystals as media for holographic interconnections in neural networks are examined. Limitations on the density of interconnections and the number of holographic associations which can be stored in photorefractive crystals are derived. Optical architectures for implementing various neural schemes are described. Experimental results are presented for one of these architectures

A critique of the SACE Review panel's report on community views

The South Australian Certificate of Education (SACE), introduced in 1992-93, is a credential and formal qualification within the Australian Qualifications Framework (AQF). SACE was recently subjected to a review that led to a series of significant recommendations. These recommendations came out of a process that began with the Review Panel scrutinising existing SACE structures for continuing validity and effectiveness. This paper critically examines claims made by the Review Panel of a resounding confirmation of the need for reform. Since the panel's claims are built upon qualitative data (community submissions), they are critiqued using widely-accepted standards for qualitative research. In particular, this paper examines the panel's evidence regarding 'academic creep', the dominance of the academic pathway, and issues regarding the Tertiary Entrance Rank. The findings suggest that the panel's case for reform may apply more to government schools than to the SACE itself. This paper concludes that the case for reform is poorly developed and largely supported by research lacking transparency and unsuited to making generalisations

A method for monitoring sub-trends in country-level mathematics achievement on TIMSS

The Trends in International Mathematics and Science studies provide country-level data for tracking changes in student achievement over time. In this paper the author has developed a method for identifying and monitoring trends in student achievement above or below any specified cut-point on these tests. The method involved the use of the Foster, Greer, and Thorbecke indices, as well as a modified version of these indices. The ability to identify and monitor trends in student achievement at various cut-points on the test should prove useful to policy analysts as well as to governmental and international funding agencies wishing to obtain data on the effectiveness of various programs and policies. [Author abstract

The SACE Review panel's final report : significant flaws in the analysis of statistical data.

The South Australian Certificate of Education (SACE) is a credential and formal qualification within the Australian Qualifications Framework. A recent review of the SACE outlined a number of recommendations for significant changes to this certificate. These recommendations were the result of a process that began with the review panel 'scrutinizing carefully [existing SACE structures for] continuing validity and effectiveness'. This paper critiques the 'careful examination' of statistical trends and patterns used to build the case for reform. Central to these trends and patterns are measures of retention, socio-economic status and student achievement, all of which are problematic. This paper also challenges the appropriateness of the statistical techniques used in the review. The paper concludes by arguing that making significant policy changes based upon such limited and flawed analyses is problematic

Mécanismes de social engineering (phishing): étude technique et économique

Les escroqueries sur internet sont nombreuses et variées. Toute personne est susceptible d’être la cible d’une attaque lors d’une navigation sur le net. De plus en plus d’escrocs n’hésitent pas à recourir au Social Engineering comme levier pour acquérir des données sensibles de manière déloyale en exploitant les failles humaines. Le phishing est une technique de Social Engineering employée par ces pirates. Il est utilisé pour subtiliser des informations personnelles dans le but de commettre une usurpation d’identité à l’insu de leurs victimes. La force de persuasion de ces escrocs est la clé de voûte d’une attaque réussie. Le but de ce travail est tout d’abord d’explorer les différentes techniques de phishing utilisées par les pirates pour ensuite identifier les mesures de protection disponibles contre ce phénomène. Enfin, nous aborderons les moyens de lutte mis en œuvre par des organismes pour tenter de combattre ce fléau

Preserving the Ocean Circulation: Implications for Climate Policy

Climate modelers have recognized the possibility of abrupt climate changes caused by a reorganization of the North Atlantic's current pattern (technically known as a thermohaline circulation collapse). This circulation system now warms north-western Europe and transports carbon dioxide to the deep oceans. The posited collapse of this system could produce severe cooling in north-western Europe, even when general global warming is in progress. In this paper we use a simple integrated assessment model to investigate the optimal policy response to this risk. Adding the constraint of avoiding a thermohaline circulation collapse would significantly reduce the allowable greenhouse gas emissions in the long run along an optimal path. Our analysis implies that relatively small damages associated with a collapse (less than 1 % of gross world product) would justify a considerable reduction of future carbon dioxide emissions.

Chameleon: a Blind Double Trapdoor Hash Function for Securing AMI Data Aggregation

Data aggregation is an integral part of Advanced Metering Infrastructure (AMI) deployment that is implemented by the concentrator. Data aggregation reduces the number of transmissions, thereby reducing communication costs and increasing the bandwidth utilization of AMI. However, the concentrator poses a great risk of being tampered with, leading to erroneous bills and possible consumer disputes. In this paper, we propose an end-to-end integrity protocol using elliptic curve based chameleon hashing to provide data integrity and authenticity. The concentrator generates and sends a chameleon hash value of the aggregated readings to the Meter Data Management System (MDMS) for verification, while the smart meter with the trapdoor key computes and sends a commitment value to the MDMS so that the resulting chameleon hash value calculated by the MDMS is equivalent to the previous hash value sent by the concentrator. By comparing the two hash values, the MDMS can validate the integrity and authenticity of the data sent by the concentrator. Compared with the discrete logarithm implementation, the ECC implementation reduces the computational cost of MDMS, concentrator and smart meter by approximately 36.8%, 80%, and 99% respectively. We also demonstrate the security soundness of our protocol through informal security analysis

Inside a Student Cohort: Teacher Education from a Social Capital Perspective

In this article, we report on student teachers perceptions of their cohort experiences. Using the lens of social capital theory, we analyzed their responses to an open-ended question on a survey and faculty members responses in focus groups. The structural properties of cohorts closure, stability, interdependence, and shared ideology facilitated the development of social capital. Closure and stability promoted social and emotional support while interdependence and shared ideology prompted both positive and negative effects. The cohort model better served some students than others. We found that students were more likely to develop social capital by bonding with their cohort peers than by bridging with those outside their cohorts. Key words: teacher candidates, student cohorts, social capital theory, bonding, bridging Dans cet article, nous présentons les perceptions détudiants en pédagogie quant aux expériences de leur cohorte. À laide de la théorie du capital social, nous avons analysé leurs réponses à une question ouverte au sujet dun sondage et des réponses de professeurs réunis en groupes de discussion. Les propriétés structurelles des cohortes fermeture, stabilité, interdépendance et idéologie commune ont facilité le développement dun capital social. La fermeture et la stabilité ont favorisé le soutien social et émotif tandis que linterdépendance et lidéologie commune ont entraîné des effets à la fois positifs et négatifs. Certains étudiants plus que dautres ont bénéficié du modèle de la cohorte. Nous avons découvert que les étudiants avaient plus chances de développer un capital social en tissant des liens avec les membres de leur cohorte quavec des personnes en dehors de leur cohorte. Mots clés: futurs enseignants, cohortes détudiants, théorie du capital social, établissement de liens