35 research outputs found
A semi-parametric approach to estimate risk functions associated with multi-dimensional exposure profiles: application to smoking and lung cancer
A common characteristic of environmental epidemiology is the multi-dimensional aspect of exposure patterns, frequently reduced to a cumulative exposure for simplicity of analysis. By adopting a flexible Bayesian clustering approach, we explore the risk function linking exposure history to disease. This approach is applied here to study the relationship between different smoking characteristics and lung cancer in the framework of a population based case control study
Male circumcision and prevalence of genital human papillomavirus infection in men : a multinational study
Background: Accumulated evidence from epidemiological studies and more recently from randomized controlled trials suggests that male circumcision (MC) may substantially protect against genital HPV infection in men. The purpose of this study was to assess the association between MC and genital HPV infection in men in a large multinational study. Methods: A total of 4072 healthy men ages 18-70 years were enrolled in a study conducted in Brazil, Mexico, and the United States. Enrollment samples combining exfoliated cells from the coronal sulcus, glans penis, shaft, and scrotum were analyzed for the presence and genotyping of HPV DNA by PCR and linear array methods. Prevalence ratios (PR) were used to estimate associations between MC and HPV detection adjusting for potential confounders. Results: MC was not associated with overall prevalence of any HPV, oncogenic HPV types or unclassified HPV types. However, MC was negatively associated with non-oncogenic HPV infections (PR 0.85, 95% confident interval: 0.76-0.95), in particular for HPV types 11, 40, 61, 71, and 81. HPV 16, 51, 62, and 84 were the most frequently identified genotypes regardless of MC status. Conclusions: This study shows no overall association between MC and genital HPV infections in men, except for certain non-oncogenic HPV types for which a weak association was found. However, the lack of association with MC might be due to the lack of anatomic site specific HPV data, for example the glans penis, the area expected to be most likely protected by MC
Moonstruck Primates: Owl Monkeys (Aotus) Need Moonlight for Nocturnal Activity in Their Natural Environment
Primates show activity patterns ranging from nocturnality to diurnality, with a few species showing activity both during day and night. Among anthropoids (monkeys, apes and humans), nocturnality is only present in the Central and South American owl monkey genus Aotus. Unlike other tropical Aotus species, the Azara's owl monkeys (A. azarai) of the subtropics have switched their activity pattern from strict nocturnality to one that also includes regular diurnal activity. Harsher climate, food availability, and the lack of predators or diurnal competitors, have all been proposed as factors favoring evolutionary switches in primate activity patterns. However, the observational nature of most field studies has limited an understanding of the mechanisms responsible for this switch in activity patterns. The goal of our study was to evaluate the hypothesis that masking, namely the stimulatory and/or inhibitory/disinhibitory effects of environmental factors on synchronized circadian locomotor activity, is a key determinant of the unusual activity pattern of Azara's owl monkeys. We use continuous long-term (6–18 months) 5-min-binned activity records obtained with actimeter collars fitted to wild owl monkeys (n = 10 individuals) to show that this different pattern results from strong masking of activity by the inhibiting and enhancing effects of ambient luminance and temperature. Conclusive evidence for the direct masking effect of light is provided by data showing that locomotor activity was almost completely inhibited when moonlight was shadowed during three lunar eclipses. Temperature also negatively masked locomotor activity, and this masking was manifested even under optimal light conditions. Our results highlight the importance of the masking of circadian rhythmicity as a determinant of nocturnality in wild owl monkeys and suggest that the stimulatory effects of dim light in nocturnal primates may have been selected as an adaptive response to moonlight. Furthermore, our data indicate that changes in sensitivity to specific environmental stimuli may have been an essential key for evolutionary switches between diurnal and nocturnal habits in primates
Wild redfronted lemurs (Eulemur rufifrons) use social information to learn new foraging techniques
Recent research has claimed that traditions are not a unique feature of human culture, but that they can be found in animal societies as well. However, the origins of traditions in animals studied in the wild are still poorly understood. To contribute comparative data to begin filling this gap, we conducted a social diffusion experiment with four groups of wild redfronted lemurs (Eulemur rufifrons). We used a ‘two-option’ feeding box, where these Malagasy primates could either pull or push a door to get access to a fruit reward to study whether and how these two behavioural traits spread through the groups. During a pre-training phase, two groups were presented with boxes in which one technique was blocked, whereas two groups were presented with unblocked boxes. During a subsequent unconstrained phase, all four groups were confronted with unblocked boxes. Nearly half of the study animals were able to learn the new feeding skill and individuals who observed others needed fewer unsuccessful task manipulations until their first successful action. Animals in the two groups with pre-training also discovered the corresponding alternative technique but preferred the seeded technique. Interestingly, animals in the two groups without pre-training discovered both techniques, and one group developed a group preference for one technique whereas the other did not. In all groups, some animals also scrounged food rewards. In conclusion, redfronted lemurs appear to use social information in acquiring a novel task, and animals in at least in one group without training developed a group preference for one technique, indicating that they have the potential to develop behavioural traditions and conformity
Use of Mangroves by Lemurs
Despite an increasing recognition of the ecosystem services provided by mangroves, we know little about their role in maintaining terrestrial biodiversity, including primates. Madagascar’s lemurs are a top global conservation priority with 94 % of species threatened with extinction, but records of their occurrence in mangroves are scarce. I used a mixed-methods approach to collect published and unpublished observations of lemurs in mangroves: I carried out a systematic literature search, and supplemented this with a targeted information request to 1243 researchers, conservation and tourism professionals and others who may have visited mangroves in Madagascar. I found references to, or observations of, at least 23 species in five families using mangroves, representing more than 20 % of lemur species and over 50 % of species whose distributions include mangrove areas. Lemurs used mangroves for foraging, sleeping and travelling between terrestrial forest patches, and some were observed as much as 3 km from the nearest permanently dry land. However most records were anecdotal and thus tell us little about lemur ecology in this habitat. Mangroves are more widely used by lemurs than has previously been recognised, and merit greater attention from primate researchers and conservationists in Madagascar
Intentional communication between wild bonnet macaques and humans
Comparative studies of nonhuman communication systems could provide insights into the origins and
evolution of a distinct dimension of human language: intentionality. Recent studies have provided
evidence for intentional communication in diferent species but generally in captive settings. We report
here a novel behaviour of food requesting from humans displayed by wild bonnet macaques Macaca
radiata, an Old World cercopithecine primate, in the Bandipur National Park of southern India. Using
both natural observations and feld experiments, we examined four diferent behavioural components—
coo-calls, hand-extension gesture, orientation, and monitoring behaviour—of food requesting for their
conformity with the established criteria of intentional communication. Our results suggest that food
requesting by bonnet macaques is potentially an intentionally produced behavioural strategy as all
the food requesting behaviours except coo-calls qualify the criteria for intentionality. We comment on
plausible hypotheses for the origin and spread of this novel behavioural strategy in the study macaque
population and speculate that the cognitive precursors for language production may be manifest in the
usage of combination of signals of diferent modalities in communication, which could have emerged in
simians earlier than in the anthropoid ape
Coordination of Group Movements in Wild Red-fronted Lemurs (Eulemur rufifrons): Processes and Influence of Ecological and Reproductive Seasonality
Development of foraging skills in two orangutan populations: needing to learn or needing to grow?
14 th Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes -2-6
Abstract: Dispersion modelling is often used to estimate potentially contaminated areas in case of accidental release of microorganisms in the atmosphere. In the specific case of Legionella, accidental spread in the atmosphere due to contaminated cooling towers system may occur over distance larger than 10km. In addition, most cooling towers are located in urban areas where dispersion due to obstacles is complex. In this case, dispersion models have to take into account complex flows and microphysical processes that occur within the plume and may have an impact on the survival of the microorganisms. To estimate the concentration of microorganisms in these areas, a specific module has been developed within the lagrangian dispersion model Micro Swift Spray (MSS, Aria technologies). This module takes into account microorganisms outside or inside water liquid droplets and microphysical interaction inside the plume. A simple biological module governing the survival of airborne microorganisms has also been implemented in the dispersion model. In order to evaluate this model, a field campaign of biological aerosols dispersion was performed by CSTB (Champs-sur-Marne, France) on June 23 rd , 2009. Spores of bacillus atrophaeus (usually referred to as BG) initially contained in a water tank were disseminated in a suburban area from a source at 3 meters above ground level. Air was sampled by DGA MNRBC (Vert-Le-Petit, France) at 4 various locations from 50 to 300 meters from the source to monitor NG concentration. Direct impaction onto Petri dishes was performed with slit-samplers and sixstage Andersen impactors. Wetted-wall cyclones and SKC Biosamplers were also implemented in order to sample air and generate liquid samples. Dispersion modelling for this campaign has been carried out by INERIS using the microorganism module developed in MSS. The results show that predicted concentrations and in situ measurements are in agreement. MSS Model was implemented to simulate legionella airborne dispersion from a virtual cooling tower at the same location. The biological model has been activated. Results show that the impact of biological model on airborne concentration is significant