Hepatitis C virus infection in South Australian prisoners : seroprevalence, seroconversion, and risk factors

Objectives : To determine entry antibody seroprevalence and seroconversion to hepatitis C virus (HCV) and associated risk factors in newly incarcerated prisoners.

Methods : Males and females entering South Australian prisons completed risk factor surveys and were offered HCV-antibody testing. Participants completed additional surveys and, if HCV-negative at last test, underwent further antibody tests at 3-monthly intervals for up to 15 months. Data were analyzed using univariate and multivariate techniques.

Results : HCV seroprevalence among 662 prison entrants was estimated at 42%. Previous injecting history was highly prevalent at entry (64%) and both community and prison injecting independently predicted entry HCV status. Tattooing was not an important risk factor. While community exposure could not be ruled out, three seroconversions were noted in 148 initially HCV-seronegative individuals occurring in a median 121 days – 4.6 per 100 person-years. Prison injecting was infrequently reported, but HCV-seropositive participants were significantly more likely to commence IDU in prison than seronegative participants (p = 0.035).

Conclusions : Entry HCV seroprevalence in South Australian prisoners is extremely high and may have contributed to a ‘ceiling effect’, minimizing the observable seroconversion rate. Greater frequency of injecting among those already infected with HCV represents a significant threat to other prisoners and prison staff.

Invasive species can't cover their tracks : using microsatellites to assist management of starling (Sturnus vulgaris) populations in Western Australia

Invasive species are known to cause environmental and economic damage, requiring management by control agencies worldwide. These species often become well established in new environments long before their detection, resulting in a lack of knowledge regarding their history and dynamics. When new invasions are discovered, information regarding the source and pathway of the invasion, and the degree of connectivity with other populations can greatly benefit management strategies. Here we use invasive common starling (Sturnus vulgaris) populations from Australia to demonstrate that genetic techniques can provide this information to aid management, even when applied to highly vagile species over continental scales. Analysis of data from 11 microsatellites in 662 individuals sampled at 17 localities across their introduced range in Australia revealed four populations. One population consisted of all sampling sites from the expansion front in Western Australia, where control efforts are focused. Despite evidence of genetic exchange over both contemporary and historical timescales, gene flow is low between this population and all three more easterly populations. This suggests that localized control of starlings on the expansion front may be an achievable goal and the long-standing practice of targeting select proximal eastern source populations may be ineffective on its own. However, even with low levels of gene flow, successful control of starlings on the expansion front will require vigilance, and genetic monitoring of this population can provide essential information to managers. The techniques used here are broadly applicable to invasive populations worldwide.

Long-term changes in abundance and distribution of microzooplankton in the NE Atlantic and North Sea

Long-term changes in mesozooplankton and phytoplankton populations have been well documented in the North Atlantic region, whereas data for microzooplankton are scarce. This neglected component of the plankton is a vital link in marine food-webs, grazing on smaller flagellates and cyanobacteria and in turn providing food for the larger mesozooplankton. We use the latest tintinnid (Ciliophora, Protista) data from the Continuous Plankton Recorder (CPR) survey in the NE Atlantic and North Sea to examine the phenology, distribution and abundance of this important group of ciliates. Presence/absence data came from 167 122 CPR samples collected between 1960 and 2009 and abundance data from 49 662 samples collected between 1996 and 2009. In the North Atlantic the genus Dictyocysta spp. dominated and Parafavella gigantea showed an increase in abundance around Iceland and Greenland. In the North Sea higher densities of Tintinnopsis spp., Favella serrata and Ptychocylis spp. were found. The presence of tintinnids in CPR samples collected in the North Atlantic has increased over the last 50 years and the seasonal window of high abundance has lengthened. Conversely in the North Sea there has been an overall reduction in abundance. We discuss possible drivers for these long-term changes and point the way forward to more holistic studies that examine how ecosystems, rather than just selected taxa, are responding to climate change.

Reconfigurable multipurpose haptic interface

This paper presents a low-cost haptic interface providing four different kinematic configurations. The different configurations are achieved using two Phantom Omni haptic devices combined with a series of clip-on attachments. Aside from the flexibility to easily reconfigure the interface, three of the four configurations provide functionality which is either not readily available or is cost prohibitive for many applications.

The 0-1 Knapsack polytope – a starting point for cryptanalysis of Knapsack ciphers?

The Knapsack Cryptosystem of Merkle and Hellman, 1978, is one of the earliest public-key cryptography schemes. The security of the method relies on the difficulty in solving Subset Sum Problems (also known as Knapsack Problems). In this paper, we first provide a brief history of knapsack-based cryptosystems and their cryptanalysis attacks. Following that, we review the advances in integer programming approaches to 0 − 1 Knapsack Problems, with a focus on the polyhedral studies of the convex hull of the integer set. Last of all, we discuss potential future research directions in applying integer programming in the cryptanalysis of knapsack ciphers.

A novel method for detecting double compressed Facebook JPEG images

Images published on online social sites such as Facebook are increasingly prone to be misused for malicious purposes. However, existing image forensic research assumes that the investigator can confiscate every piece of evidence and hence overlooks the fact that the original image is difficult to obtain. Because Facebook applies a Discrete Cosine Transform (DCT)-based compression on uploaded images, we are able to detect the modified images which are re-uploaded to Facebook. Specifically, we propose a novel method to effectively detect the presence of double compression via the spatial domain of the image: We select small image patches from a given image, define a distance metric to measure the differences between compressed images, and propose an algorithm to infer whether the given image is double compressed without referring to the original image. To demonstrate the correctness of our algorithm, we correctly predict the number of compressions being applied to a Facebook image.

A competitive three-level pruning technique for information security

The reduction of size of ensemble classifiers is important for various security applications. The majority of known pruning algorithms belong to the following three categories: ranking based, clustering based, and optimization based methods. The present paper introduces and investigates a new pruning technique. It is called a Three-Level Pruning Technique, TLPT, because it simultaneously combines all three approaches in three levels of the process. This paper investigates the TLPT method combining the state-of-the-art ranking of the Ensemble Pruning via Individual Contribution ordering, EPIC, the clustering of the K-Means Pruning, KMP, and the optimisation method of Directed Hill Climbing Ensemble Pruning, DHCEP, for a phishing dataset. Our new experiments presented in this paper show that the TLPT is competitive in comparison to EPIC, KMP and DHCEP, and can achieve better outcomes. These experimental results demonstrate the effectiveness of the TLPT technique in this example of information security application.

Forensic identification of students outsourcing assignment projects from freelancer.com

This paper reports the increasing popularity of outsourcing academic works by university students motivated by the lure of lucrative dividends and visa opportunities. Due to a lack of formal methods in detecting such transactions, freelance websites are thriving in facilitating the trade of outsourced assignments. This is compounded by the fact that many university staff have neither the time nor training to perform complex media analysis and forensic investigations. This paper proposes a method to aid in the identification of those who outsource assignment works on the most popular site freelancer.com. We include a recent real-world case study to demonstrate the relevancy and applicability of our methodology. In this case study, a suspect attempts to evade detection via use of anti-forensics which demonstrates the capability and awareness of evasion techniques used by students.

A primer on phylogenetic generalised least squares

Phylogenetic generalised least squares (PGLS) is one of the most commonly employed phylogenetic comparative methods. The technique, a modification of generalised least squares, uses knowledge of phylogenetic relationships to produce an estimate of expected covariance in cross-species data. Closely related species are assumed to have more similar traits because of their shared ancestry and hence produce more similar residuals from the least squares regression line. By taking into account the expected covariance structure of these residuals, modified slope and intercept estimates are generated that can account for interspecific autocorrelation due to phylogeny. Here, we provide a basic conceptual background to PGLS, for those unfamiliar with the approach. We describe the requirements for a PGLS analysis and highlight the packages that can be used to implement the method. We show how phylogeny is used to calculate the expected covariance structure in the data and how this is applied to the generalised least squares regression equation. We demonstrate how PGLS can incorporate information about phylogenetic signal, the extent to which closely related species truly are similar, and how it controls for this signal appropriately, thereby negating concerns about unnecessarily ‘correcting’ for phylogeny. In addition to discussing the appropriate way to present the results of PGLS analyses, we highlight some common misconceptions about the approach and commonly encountered problems with the method. These include misunderstandings about what phylogenetic signal refers to in the context of PGLS (residuals errors, not the traits themselves), and issues associated with unknown or uncertain phylogeny.

Location privacy preserving for semantic-aware applications

With the increase use of location-based services, location privacy has recently raised serious concerns. To protect a user from being identified, a cloaked spatial region that contains other k-1 nearest neighbors of the user is used to replace the accurate position. In this paper, we consider location-aware applications that services are different among regions. To search nearest neighbors, we define a novel distance measurement that combines the semantic distance and the Euclidean distance to address the privacy preserving issue in the above-mentioned applications. We also propose an algorithm kNNH to implement our proposed method. The experimental results further suggest that the proposed distance metric and the algorithm can successfully retain the utility of the location services while preserving users’ privacy.

Australia

The book provides an analysis of the grocery retail market in a very large number of countries with an international report written by an economist. The chapter on Australia describes how the law in Australia addresses competition concerns arising from the grocery retail market, analyses its success in addressing these concerns and considers possible future reform.