The static allometry of sexual and non-sexual traits in vervet monkeys

Sexual traits vary tremendously in static allometry. This variation may be explained in part by body size-related differences in the strength of selection. We tested this hypothesis in two populations of vervet monkeys, using estimates of the level of condition dependence for different morphological traits as a proxy for body size-related variation in the strength of selection. In support of the hypothesis, we found that the steepness of allometric slopes increased with the level of condition dependence. One trait of particular interest, the penis, had shallow allometric slopes and low levels of condition dependence, in agreement with one of the most consistent patterns yet detected in the study of allometry, namely that of genitalia exhibiting shallow allometries.This research was supported by NIH grant R01RR0163009

Calibration artefacts in radio interferometry. I. Ghost sources in WSRT data

This work investigates a particular class of artefacts, or ghost sources, in radio interferometric images. Earlier observations with (and simulations of) the Westerbork Synthesis Radio Telescope (WSRT) suggested that these were due to calibration with incomplete sky models. A theoretical framework is derived that validates this suggestion, and provides predictions of ghost formation in a two-source scenario. The predictions are found to accurately match the result of simulations, and qualitatively reproduce the ghosts previously seen in observational data. The theory also provides explanations for many previously puzzling features of these artefacts (regular geometry, PSF-like sidelobes, seeming independence on model flux), and shows that the observed phenomenon of flux suppression affecting unmodelled sources is due to the same mechanism. We demonstrate that this ghost formation mechanism is a fundamental feature of calibration, and exhibits a particularly strong and localized signature due to array redundancy. To some extent this mechanism will affect all observations (including those with non-redundant arrays), though in most cases the ghosts remain hidden below the noise or masked by other instrumental artefacts. The implications of such errors on future deep observations are discussed.Comment: 19 pages, 15 figures, submitted to MNRA

Comparative growth and static allometry in the genus Chlorocebus

Characterizing variation in growth across populations is critical to understanding multiple aspects of development in primates, including within-taxon developmental plasticity and the evolution of life history patterns. Growth in wild primates has often been reported and directly compared across larger taxonomic groups and within social groups, but comparisons are rarely investigated across widely dispersed populations of a single taxon. With the Vervet Phenome-Genome Project and the International Vervet Research Consortium, we trapped 936 vervet monkeys of all ages representing three populations (Kenyan pygerythrus, South African pygerythrus, and sabaeus from St. Kitts & Nevis). We gathered 10 different body measurements from each including mass, body breadth and length, segmental limb lengths, and chest circumference. To gain a better understanding of how ontogenetic patterns vary in these populations, we calculated bivariate allometry coefficients, derived using PCA on log-transformed and z-standardized trait values, and compared them to isometric vector coefficients. Within all population samples, around weaning age most traits showed a negative allometric relationship to body length. As each population ages, however, distinct patterns emerge, showing population differences in onset and intensity of growth among traits. In concordance with other analyses on growth in these populations, our results suggest that there exist relative differences in patterns of growth between Chlorocebus populations, further suggesting selection for unique developmental pathways in each

Lexicographic cones and the ordered projective tensor product

We introduce lexicographic cones, a method of assigning an ordered vector space \Lex(S) to a poset $S$, generalising the standard lexicographic cone. These lexicographic cones are then used to prove that the projective tensor cone of two arbitrary cones is a cone, and to find a new characterisation of finite-dimensional vector lattices.Comment: 8 page

HIV prevention trial design in an era of effective pre-exposure prophylaxis

Pre-exposure prophylaxis (PrEP) has demonstrated remarkable effectiveness protecting at-risk individuals from HIV-1 infection. Despite this record of effectiveness, concerns persist about the diminished protective effect observed in women compared with men and the influence of adherence and risk behaviors on effectiveness in targeted subpopulations. Furthermore, the high prophylactic efficacy of the first PrEP agent, tenofovir disoproxil fumarate/emtricitabine (TDF/FTC), presents challenges for demonstrating the efficacy of new candidates. Trials of new agents would typically require use of non-inferiority (NI) designs in which acceptable efficacy for an experimental agent is determined using pre-defined margins based on the efficacy of the proven active comparator (i.e. TDF/FTC) in placebo-controlled trials. Setting NI margins is a critical step in designing registrational studies. Under- or over-estimation of the margin can call into question the utility of the study in the registration package. The dependence on previous placebo-controlled trials introduces the same issues as external/historical controls. These issues will need to be addressed using trial design features such as re-estimated NI margins, enrichment strategies, run-in periods, crossover between study arms, and adaptive re-estimation of sample sizes. These measures and other innovations can help to ensure that new PrEP agents are made available to the public using stringent standards of evidence

Social media in the healthcare context: Ethical challenges and recommendations

The popularity of social media has grown rapidly and healthcare practitioners and students commonly use sites such as Facebook. The ethical and professional implications and their benefits and hazards must be considered. Concerns include blurring of boundaries between an individual’s public and professional lives, maintaining privacy and confidentiality of patient information, damaging the public image of the profession and inter-professional relationships. The same laws that apply to conduct in the real world also apply in cyberspace. Harmful or derogatory posts may result in a defamation lawsuit. The internet may also provide opportunities for patient education through peerreviewed websites and to build professional networks. Institutions should have policies on the uses of social media. Emerging technology will continue to change the landscape of social media and social networking and the way patients and practitioners use websites will continue to evolve. Practitioners should proactively manage digital identity by reviewing publicly available material and maintaining strict privacy settings about their information

Conceptualisation of an ethical risk assessment for higher education institutions

This article examines an ethical risk assessment conducted in one of South African largest higher education institutions. A statistical analysis of 1 687 respondents participating in the original ethical risk assessment survey was conducted. Confirmatory factor analyses supported a higher order, multidimensional model of three main factors, namely institutional ethical leadership orientation, individual/employee ethical orientation and institutional student-centeredness/orientation. Based on this examination and analysis this three-factor structure provides sufficient evidence of a conceptual ethical framework to be further tested empirically and used within higher education institutions

Religiousness: An Inter-Disciplinary, Multi-Demographical and Multi-Regional Study

This study was based on an interdisciplinary paradigm for religious research, with the manifestation of inter-disciplinarity in terms of content (the specific field being the psychology of religion which traditionally coincide within two separate disciplines), as well as the methodology (embracing a true positivistic approach). Although 40 624 individuals from a large public service institution in South Africa participated in the study, only 32 413 datasets were usable for this study. Religiousness, comprising of two factors, namely Salience and Participation was measured. The instrument reported an acceptable internal consistency in terms of the Cronbach alpha coefficient and inter-item correlation. High reliability scores were reported on the eight Salience and three Participation items. Overall, religion was seen as an important aspect in the lives of all the participants. All the participants had a positive attitude towards religion and all agreed that religion played an important part in their family life, their wellness, their work performance and in their relationships with others. The overall participation in religious activities, including the involvement in Religious leadership roles, the frequency of Religious participation, as well as the extent of Religious expression, measured high. Religiousness (expressed as the aggregate score of the two factors) measured high, which is an indication that the participants generally believed in a higher power and had positive attitudes towards institutional/religion-specific practices. The participants also indicated that they valued religion as an important aspect of their lives. No meaningful inferences could be made in terms of the impact of race, gender, age and the specific religion on Religiousness

Effects on mortality of a nutritional intervention for malnourished HIV-infected adults referred for antiretroviral therapy: a randomised controlled trial.

Malnourished HIV-infected African adults are at high risk of early mortality after starting antiretroviral therapy (ART). We hypothesized that short-course, high-dose vitamin and mineral supplementation in lipid nutritional supplements would decrease mortality