196,843 research outputs found
Begon, M., Harper, J.L. & Townsend, C.R. — Ecology, Individuals, populations and communities. Blackwell, Oxford, 1986
No full textBourlière François. Begon, M., Harper, J.L. & Townsend, C.R. — Ecology, Individuals, populations and communities. Blackwell, Oxford, 1986. In: Revue d'Écologie (La Terre et La Vie), tome 42, n°2, 1987. p. 205
Demande de congés de M. le comte de La Rouzière, le 17 septembre 1789
No full textRouzière François Louis Begon de la. Demande de congés de M. le comte de La Rouzière, le 17 septembre 1789. In: Archives Parlementaires de 1787 à 1860 - Première série (1787-1799) Tome IX - Du 16 septembre au 11 novembre 1789. Paris : Librairie Administrative P. Dupont, 1877. p. 24
Demande de congés de M. le comte de La Rouzière, le 17 septembre 1789
No full textRouzière François Louis Begon de la. Demande de congés de M. le comte de La Rouzière, le 17 septembre 1789. In: Archives Parlementaires de 1787 à 1860 - Première série (1787-1799) Tome IX - Du 16 septembre au 11 novembre 1789. Paris : Librairie Administrative P. Dupont, 1877. p. 24
Cowpox virus infection in natural field vole Microtus agrestispopulations: significant negative impacts on survival
No full text1. Cowpox virus is an endemic virus circulating in populations of wild rodents. It has been implicated as a potential cause of population cycles in field voles Microtus agrestis L., in Britain, owing to a delayed density-dependent pattern in prevalence, but its impact on field vole demographic parameters is unknown. This study tests the hypothesis that wild field voles infected with cowpox virus have a lower probability of survival than uninfected individuals. 2. The effect of cowpox virus infection on the probability of an individual surviving to the next month was investigated using longitudinal data collected over 2 years from four grassland sites in Kielder Forest, UK. This effect was also investigated at the population level, by examining whether infection prevalence explained temporal variation in survival rates, once other factors influencing survival had been controlled for. 3. Individuals with a probability of infection, P(I), of 1 at a time when base survival rate was at median levels had a 22.4% lower estimated probability of survival than uninfected individuals, whereas those with a P(I) of 0.5 had a 10.4% lower survival. 4. At the population level, survival rates also decreased with increasing cowpox prevalence, with lower survival rates in months of higher cowpox prevalence. 5. Simple matrix projection models with 28 day time steps and two stages, with 71% of voles experiencing cowpox infection in their second month of life (the average observed seroprevalence at the end of the breeding season) predict a reduction in 28-day population growth rate during the breeding season from λ = 1.62 to 1.53 for populations with no cowpox infection compared with infected populations. 6. This negative correlation between cowpox virus infection and field vole survival, with its potentially significant effect on population growth rate, is the first for an endemic pathogen in a cyclic population of wild rodents
Effect of trunk sagittal attitude on shoulder, thorax and pelvis three-dimensional kinematics in able-bodied subjects during gait
No full textIt has been shown that an original attitude in forward or backward inclination of the trunk is maintained at gait initiation
and during locomotion, and that this affects lower limb loading patterns. However, no studies have shown the extent to
which shoulder, thorax and pelvis three-dimensional kinematics are modified during gait due to this sagittal inclination
attitude. Thirty young healthy volunteers were analyzed during level walking with video-based motion analysis. Reflecting
markers were mounted on anatomical landmarks to form a two-marker shoulder line segment, and a four-marker thorax
and pelvis segments. Absolute and relative spatial rotations were calculated, for a total of 11 degrees of freedom. The
subjects were divided into two groups of 15 according to the median of mean thorax inclination angle over the gait cycle.
Preliminary MANOVA analysis assessed whether gender was an independent variable. Then two-factor nested ANOVA was
used to test the possible effect of thorax inclination on body segments, planes of motion and gait periods, separately. There
was no significant difference in all anthropometric and spatio-temporal parameters between the two groups, except for
subject mass. The three-dimensional kinematics of the thorax and pelvis were not affected by gender. Nested ANOVA
revealed group effect in all segment rotations apart those at the pelvis, in the sagittal and frontal planes, and at the pushoff.
Attitudes in sagittal thorax inclination altered trunk segments kinematics during gait. Subjects with a backward thorax
showed less thorax-to-pelvis motion, but more shoulder-to-thorax and thorax-to-laboratory motion, less motion in flexion/
extension and in lateral bending, and also less motion during push-off. This contributes to the understanding of forward
propulsion and sideways load transfer mechanisms, fundamental for the maintenance of balance and the risk of falling
Begon, M., Townensend, C. R. & Harper, J. L. — Ecology. From individuals to ecosystems. 4e édition. Blackwell Publishing, Malden, Oxford & Carlton. 2005
No full textErard Christian. Begon, M., Townensend, C. R. & Harper, J. L. — Ecology. From individuals to ecosystems. 4e édition. Blackwell Publishing, Malden, Oxford & Carlton. 2005. In: Revue d'Écologie (La Terre et La Vie), tome 60, n°4, 2005. p. 383
A coupled hidden Markov model for disease interactions
No full textTo investigate interactions between parasite species in a host, a population of field voles was studied longitudinally, with presence or absence of six different parasites measured repeatedly. Although trapping sessions were regular, a different set of voles was caught at each session, leading to incomplete profiles for all subjects. We use a discrete time hidden Markov model for each disease with transition probabilities dependent on covariates via a set of logistic regressions. For each disease the hidden states for each of the other diseases at a given time point form part of the covariate set for the Markov transition probabilities from that time point. This allows us to gauge the influence of each parasite species on the transition probabilities for each of the other parasite species. Inference is performed via a Gibbs sampler, which cycles through each of the diseases, first using an adaptive Metropolis–Hastings step to sample from the conditional posterior of the covariate parameters for that particular disease given the hidden states for all other diseases and then sampling from the hidden states for that disease given the parameters. We find evidence for interactions between several pairs of parasites and of an acquired immune response for two of the parasites
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Automatic differentiation algorithms in model analysis
No full textTitle: Automatic differentiation algorithms in model analysisAuthor: M.J. HuiskesDate: 19 March, 2002In this thesis automatic differentiation algorithms and derivative-based methods are combined to develop efficient tools for model analysis. Automatic differentiation algorithms comprise a class of algorithms aimed at the derivative computation of functions that are represented as computer code. Derivative-based methods that may be implemented using these algorithms are presented for sensitivity analysis and statistical inference, particularly in the context of nonlinear parameter estimation.Local methods of sensitivity analysis are discussed for both explicit and implicit relations between variables. Particular attention is paid to propagation of uncertainty, and to the subsequent uncertainty decomposition of output uncertainty in the various sources of input uncertainty.Statistical methods are presented for the computation of accurate inferential information for nonlinear parameter estimation problems by means of higher-order derivatives of the model functions. Methods are also discussed for the assessment of the appropriateness of model structure complexity in relation to quality of data.To realize and demonstrate the potential of routines for model analysis based on automatic differentiation a software library is developed: a C++ library for the analysis of nonlinear models that can be represented by differentiable functions in which the methods for parameter estimation, statistical inference, model selection and sensitivity analysis are implemented. Several experiments are performed to assess the performance of the library. The application of the derivative-based methods and the routines of the library is further demonstrated by means of a number of case studies in ecological assessment. In two studies, large parameter estimation procedures for fish stock assessment are analyzed: for the Pacific halibut and North Sea herring species. The derivative-based methods of sensitivity analysis are applied in a study on the contribution of Russian forests to the global carbon cycle
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