An analysis of the use of graphics for information retrieval

Several research groups have addressed the problem of retrieving vector graphics. This work has, however, focused either on domain-dependent areas or was based on very simple graphics languages. Here we take a fresh look at the issue of graphics retrieval in general and in particular at the tasks which retrieval systems must support. The paper presents a series of case studies which explored the needs of professionals in the hope that these needs can help direct future graphics IR research. Suggested modelling techniques for some of the graphic collections are also presented

Education and Youth Unemployment in South Africa

The problem of high youth unemployment is a global phenomenon. According to an International Labour Office study in 2004, youth (15-24) make up nearly half (47%) of the world's unemployed, 88 million out of 186 million, even though youth are only 25% of the world's working age population. Of the world's 550 million working poor who cannot lift themselves above US $1 per day poverty measure, 150 million are youth. The ILO estimated in 2004 that halving global youth unemployment would increase global GDP by US$2.2 trillion, 4% of global GDP. These statistics lend weight to the notion that youth unemployment is a problem worthy of attention. In addition, one may argue that addressing unemployment in general would also lower poverty levels and add to GDP (World Bank 2006).

Our Vulnerable Teenagers: Their Victimization, Its Consequences, and Directions for Prevention and Intervention

Teenagers are twice as likely as any other age group to be victims of violent crime, and one in five teenagers report being the victim of a violent crime, according to a new report. The single greatest factor in predicting criminal behavior on the part of teenagers, the report also found, was not teenage pregnancy, drug use, or truancy, but whether they had been a victim of crime. This publication provides a new and comprehensive analysis of existing -- but largely unnoticed -- research and data on the crime experiences of American teenagers ages 12-19, who make up about 14 percent of the general population, but represent 25 percent of victims of violent crime

Low Cost and Compact Quantum Cryptography

We present the design of a novel free-space quantum cryptography system, complete with purpose-built software, that can operate in daylight conditions. The transmitter and receiver modules are built using inexpensive off-the-shelf components. Both modules are compact allowing the generation of renewed shared secrets on demand over a short range of a few metres. An analysis of the software is shown as well as results of error rates and therefore shared secret yields at varying background light levels. As the system is designed to eventually work in short-range consumer applications, we also present a use scenario where the consumer can regularly 'top up' a store of secrets for use in a variety of one-time-pad and authentication protocols.Comment: 18 pages, 9 figures, to be published in New Journal of Physic

Guarding Networks Through Heterogeneous Mobile Guards

In this article, the issue of guarding multi-agent systems against a sequence of intruder attacks through mobile heterogeneous guards (guards with different ranges) is discussed. The article makes use of graph theoretic abstractions of such systems in which agents are the nodes of a graph and edges represent interconnections between agents. Guards represent specialized mobile agents on specific nodes with capabilities to successfully detect and respond to an attack within their guarding range. Using this abstraction, the article addresses the problem in the context of eternal security problem in graphs. Eternal security refers to securing all the nodes in a graph against an infinite sequence of intruder attacks by a certain minimum number of guards. This paper makes use of heterogeneous guards and addresses all the components of the eternal security problem including the number of guards, their deployment and movement strategies. In the proposed solution, a graph is decomposed into clusters and a guard with appropriate range is then assigned to each cluster. These guards ensure that all nodes within their corresponding cluster are being protected at all times, thereby achieving the eternal security in the graph.Comment: American Control Conference, Chicago, IL, 201

Using resource graphs to represent conceptual change

We introduce resource graphs, a representation of linked ideas used when reasoning about specific contexts in physics. Our model is consistent with previous descriptions of resources and coordination classes. It can represent mesoscopic scales that are neither knowledge-in-pieces or large-scale concepts. We use resource graphs to describe several forms of conceptual change: incremental, cascade, wholesale, and dual construction. For each, we give evidence from the physics education research literature to show examples of each form of conceptual change. Where possible, we compare our representation to models used by other researchers. Building on our representation, we introduce a new form of conceptual change, differentiation, and suggest several experimental studies that would help understand the differences between reform-based curricula.Comment: 27 pages, 14 figures, no tables. Submitted for publication to the Physical Review Special Topics Physics Education Research on March 8, 200