The threshold for jigsaw percolation on random graphs

Jigsaw percolation is a model for the process of solving puzzles within a social network, which was recently proposed by Brummitt, Chatterjee, Dey and Sivakoff. In the model there are two graphs on a single vertex set (the `people' graph and the `puzzle' graph), and vertices merge to form components if they are joined by an edge of each graph. These components then merge to form larger components if again there is an edge of each graph joining them, and so on. Percolation is said to occur if the process terminates with a single component containing every vertex. In this note we determine the threshold for percolation up to a constant factor, in the case where both graphs are Erd\H{o}s--R\'enyi random graphs.Comment: 13 page

A Review of Issues Pertaining to Transgenic Turfgrasses

Recombinant DNA technology is a rapidly growing field in plant and animal breeding. This technology involves the transfer of pieces of DNA, or genes, regardless of the organisms involved or how they are related. Transformation procedures in plants were first developed for important crop and model plant systems. Although turfgrass management and production is one of the fastest growing areas of agriculture, genetic transformation of turfgrasses lags behind that of many other important crop plants. Turfgrasses are becoming more important primarily because of their association with the ever-increasing urban population. The size of the turfgrass seed market is second only to that of hybrid seed corn (Lee, 1996). However, much less is known about the genetics and physiology of turfgrasses. Many are polyploid, perennial, and/or outcrossing. These characteristics make them more difficult to study than many other crop plants. Use of transgenic technology in turfgrasses will likely follow as interest and corporate motivations allow. Application of transgenic technology is virtually limitless. The past few years have seen a rapid increase in releases of transgenic plants. Between 1987 and 1997, 3330 permits and notifications were filed with the U.S. Dept. of Agriculture (USDA–APHIS, 1998) for release of genetically engineered organisms in the United States. Twenty-nine percent involved herbicide tolerance and 24% insect resistance. Compared with the major crop species, genetically engineered turfgrasses are uncommon. By Dec. 1998, 31 permits and notifications had been filed on creeping bentgrass (Agrostis stolonifera L.) and two notifications on Kentucky bluegrass (Poa pratensis L.) (USDA–APHIS, 1998). But as additional genes are identified and cloned, a myriad of traits will probably be introduced into the turfgrasses. The first applications of transformation in turfgrasses were the incorporation of glufosinate [N,N-bis (phosphomethyl)glycine] resistance into creeping bentgrass (Lee et al., 1996; Liu et al., 1998), allowing application of a very effective nonselective herbicide to control unwanted weeds or other turfgrasses. In the future, recombinant DNA technology may be used to introduce other traits, such as insect resistance, disease resistance, and improved environmental stress tolerance. Transformation technology may offer many economic and agronomic benefits that are difficult or impossible to achieve through traditional breeding techniques (Dale, 1993). Essential steps of recombinant DNA technology include identification of the gene of interest, its isolation (cloning), study of the gene’s function and regulation, and introduction of the gene and expression factors into cells (Marois et al., 1991). Finally, the traits must be evaluated in an agriculturally desirable genotype

Compiler support for parallel evaluation of C++ constant expressions

Metaprogramming, the practice of writing programs that manipulate other programs at compile-time, continues to impact software development; enabling new approaches to optimisation, static analysis, and reflection. Nevertheless, a significant challenge associated with advanced metaprogramming techniques, including the constexpr functionality introduced to C++ in 2011, is an increase in compilation times. This paper presents ClangOz, a novel Clang-based research compiler that addresses this issue by evaluating relevant constant expressions in parallel, thereby reducing compilation time

Affordable Mobile-based Simulator for Robotic Surgery

Robotic surgery and novel surgical instrumentation present great potentials towards safer, more accurate and consistent minimally invasive surgery. However, their adoption is dependent to the access to training facilities and extensive surgical training. Robotic instruments require different dexterity skills compared to open or laparoscopic. Surgeons, therefore, are required to invest significant time by attending extensive training programs. Contrary, hands on experiences represent an additional operational cost for hospitals as the availability of robotic systems for training purposes is limited. All these technological and financial barriers for surgeons and hospitals hinder the adoption of robotic surgery. In this paper, we present a mobile dexterity training kit to develop basic surgical techniques within an affordable setting. The system could be used to train basic surgical gestures and to develop the motor skills needed for manoeuvring robotic instruments. Our work presents the architecture and components needed to create a simulated environment for training sub-tasks as well as a design for portable mobile manipulators that can be used as master controllers of different instruments. A preliminary study results demonstrate usability and skills development with this system.Comment: Hamlyn Symposium on Medical Robotics 201

Sex ratios of Mountain Plovers from egg production to fledging

Skewed sex ratios can have negative implications for population growth if they do not match a species’ life history. A skewed tertiary sex ratio has been detected in a population of Mountain Plover (Charadrius montanus), a grassland shorebird experiencing population declines. To study the cause of the observed male skew, we examined three early life stages between egg and fledgling in eastern Colorado from 2010 to 2012. This allows us to distinguish between egg production and chick survival as an explanation for the observed skew. We examined the primary sex ratio in eggs produced and the secondary sex ratio in hatched chicks to see if the sex ratio bias occurs before hatching. We also determined the sex ratio at fledging to reveal sex-specific mortality of nestlings. The primary sex ratio was 1.01 (± 0.01) males per female. The secondary sex ratio consisted of 1.10 (± 0.02) males per female. The probability of a chick surviving to fledging differed between males (0.55 ± 0.13) and females (0.47 ± 0.15), but the precision of these survival estimates was low. Sex ratios in early life stages of the Mountain Plover do not explain the skewed sex ratio observed in adults in this breeding population

Brucellosis in Montana Elk: Factors that Influence Disease Prevalence and the Social And Political Influences and Issues Associated with Managing a Disease of Concern for Livestock in a Free-Ranging Elk Population

Brucellosis is a bacterial disease that affects elk (Cervus elaphus), bison (Bison bison) and domestic cattle. Transmitted primarily through contact with birth tissues, the disease is a significant livestock disease resulting in significant costs to producers and is a USDA eradication program disease. Brucellosis was first documented in wildlife in the Greater Yellowstone Area (GYA) in the early 1900s and was brought into the region by livestock producers. The disease has since been eradicated in livestock, but persists in elk and bison populations of the GYA. Recently the seroprevalence of brucellosis in free-ranging elk populations of Montana has increased and its range has likely expanded resulting in increased pressure on Montana Fish, Wildlife and Parks (MFWP) to manage the disease in elk. We evaluated factors that potentially influence elk aggregation behaviors and the consequences of these factors on seroprevalence. We used a Bayesian spatial model to estimate seroprevalence across the designated surveillance area. This research approach allowed seroprevalence to be estimated for the first time in areas with limited surveillance data. The socio-political influences associated with managing wildlife potentially infected with a disease that threatens the cattle industry of Montana, the available tools for managing the disease in elk, and MFWP’s current strategy for managing brucellosis in one of Montana greatest public trusts is discussed

Meningococcal disease in children in Merseyside, England:a 31 year descriptive study

Meningococcal disease (MCD) is the leading infectious cause of death in early childhood in the United Kingdom, making it a public health priority. MCD most commonly presents as meningococcal meningitis (MM), septicaemia (MS), or as a combination of the two syndromes (MM/MS). We describe the changing epidemiology and clinical presentation of MCD, and explore associations with socioeconomic status and other risk factors. A hospital-based study of children admitted to a tertiary children's centre, Alder Hey Children's Foundation Trust, with MCD, was undertaken between 1977 to 2007 (n = 1157). Demographics, clinical presentations, microbiological confirmation and measures of deprivation were described. The majority of cases occurred in the 1-4 year age group and there was a dramatic fall in serogroup C cases observed with the introduction of the meningococcal C conjugate (MCC) vaccine. The proportion of MS cases increased over the study period, from 11% in the first quarter to 35% in the final quarter. Presentation with MS (compared to MM) and serogroup C disease (compared to serogroup B) were demonstrated to be independent risk factors for mortality, with odds ratios of 3.5 (95% CI 1.18 to 10.08) and 2.18 (95% CI 1.26 to 3.80) respectively. Cases admitted to Alder Hey were from a relatively more deprived population (mean Townsend score 1.25, 95% CI 1.09 to 1.41) than the Merseyside reference population. Our findings represent one of the largest single-centre studies of MCD. The presentation of MS is confirmed to be a risk factor of mortality from MCD. Our study supports the association between social deprivation and MCD