Estimating loss of Brucella abortus antibodies from age-specific serological data in elk

Serological data are one of the primary sources of information for disease monitoring in wildlife. However, the duration of the seropositive status of exposed individuals is almost always unknown for many free-ranging host species. Directly estimating rates of antibody loss typically requires difficult longitudinal sampling of individuals following seroconversion. Instead, we propose a Bayesian statistical approach linking age and serological data to a mechanistic epidemiological model to infer brucellosis infection, the probability of antibody loss, and recovery rates of elk (Cervus canadensis) in the Greater Yellowstone Ecosystem. We found that seroprevalence declined above the age of ten, with no evidence of disease-induced mortality. The probability of antibody loss was estimated to be 0.70 per year after a five-year period of seropositivity and the basic reproduction number for brucellosis to 2.13. Our results suggest that individuals are unlikely to become re-infected because models with this mechanism were unable to reproduce a significant decline in seroprevalence in older individuals. This study highlights the possible implications of antibody loss, which could bias our estimation of critical epidemiological parameters for wildlife disease management based on serological data

Every Vote Counts: Ensuring Integrity in Large-Scale DRE-based Electronic Voting

This paper presents a new and complete cryptographic e-voting system, called Direct Recording Electronic with Integrity (DRE-i). The DRE is a widely deployed voting system that commonly uses touch-screen technology to directly record votes. However, a lack of tallying integrity has been considered the most contentious problem with the DRE system. In this work, we take a broad interpretation of the DRE: which includes not only touch-screen machines, as deployed at polling stations, but also remote voting systems conducted over the Internet or mobile phones. In all cases, the system records votes directly. The DRE-i protocol is generic for both on-site and remote voting; it provides a drop-in mathematical solution to ensure tallying integrity even if the DRE machine is completely corrupted. Besides the tallying integrity, we also describe procedural means to protect voter\u27s privacy in a complete system. As compared with the currently well-known Helios e-voting system, our work represents a significant improvement in two main aspects. First, it permits a thin client: a web-based implementation of DRE-i does not require any Java plug-in to be installed or Javascript to be enabled. Second, it is self-tallying: as we adopt a novel technique to encrypt votes, anyone can tally votes by simply multiplying ciphertexts without needing any private keys or tallying authority involvement