Genetic and environmental constraints causing species’ range limits

Human-caused global change has led to shifts in the geographic distribution of many wild species. This has renewed the interest of understanding the factors that shape species’ contemporary range limits from both an ecological and evolutionary perspective. Recent evolutionary theory particularly emphasized the role of past demographic processes and neutral evolution in contributing to range limits. The aim of my thesis was to study these factors and their interaction with the environment experienced at range edges in an empirical system, the North American plant Arabidopsis lyrata. By crossing populations of varying range position and demographic history, and raising their offspring in gardens distributed across and beyond the species range, I found that populations with a history of small size due to past range expansion or rear-edge isolation suffered from increased expression of mutational load driven by genetic drift. This latter effect was even stronger under environmental stress, particularly under a warmer climate. Furthermore, populations at range edges with heightened past exposure to genetic drift had a reduced signature of climate adaptation. Finally, I compared A. lyrata and a novel species it gave rise to, A. arenicola, with a more northern distribution, in a climate chamber experiment. This new taxon diverged from A. lyrata in coping with a cool climate and strong reproductive isolation, most likely allowing it to to colonize subarctic regions and escape maladaptive gene flow. Results generally support the newer evolutionary theory about a predominant role of neutral evolution in contributing to geographic range limits, via genetic drift opposing purifying and directional selection. The study of sister taxa however shows that these constraints to evolution at range limits are not absolute, and can be broken

La bourgeoisie catholique au Conseil d'État (1789-1914)

Prenant appui sur une prosopographie des membres du Conseil d’État entre 1879 et 1914, l’article se propose de présenter les outils dont dispose l’historien pour apprécier la nature du catholicisme de la bourgeoisie de fonction. Il s’agit de comprendre comment révéler une «foi des tièdes», discrète mais essentielle, à partir d’archives et de témoignages sur un groupe social, mais aussi de discuter des catégories traditionnelles de l’histoire religieuse et de mettre en lumière une partie peu étudiée du peuple des fidèles. Les résultats de l’enquête permettent d’esquisser le tableau d’un monde où la religion est d’abord appréciée comme une pratique sociale. Se révèle alors la nature des liens entre les conventions bourgeoises, la religion catholique et les pratiques juridiques.Based on a prosopography of the members of the Conseil d’État between 1879 and 1914, this article attempts to present the means whereby the historian can analyse the Catholicism of the bourgeoisie in state service. The challenge is to reveal the discreet but crucial ‘faith of the lukewarm’, by using archives and testimony relating to a social group, but also to examine the traditional categories of religious history and to illuminate a rarely studied part of the faithful. The results of the enquiry enable us to portray a world in which religion is primarily valued as a social practice. This in turn reveals the nature of the connections between bourgeois conventions, the Catholic religion and juridical practices

3D musculo-skeletal finite element analysis of the foot kinematics under muscle activation with and without ankle arthrodesis

International audienceThe choice between arthrodesis and arthroplasty in the context of advanced ankle arthrosis remains a highly disputed topic in the field of foot and ankle surgery. Arthrodesis, however, represents the most popular option. Biomechanical modeling has been widely used to investigate static loading of cadaveric feet as well as consequences of arthrodesis on bony structures. Although foot kinematics has been studied using motion analysis, this approach lacks accuracy in capturing internal joints motion due to limitations inherent to external “marker sets” and the fact that it imposed the foot to be considered as a rigid solid. The consequences of arthrodesis on kinematics of the unloaded foot are not well understood although it is of crucial importance during the swing phase and at heel contact. Investigating ankle mobility during muscle contraction with and without arthrosis could explain how the motion is produced by extrinsic muscles activations affected by an arthrodesis. This study aims at defining if a biomechanical model with Finite Elements could help arthrodesis understanding

Modéliser les tissus mous pour mieux prévenir les escarres.

National audienceLa prévalence des escarres du blessé médullaire reste aujourd'hui très (trop) importante. Quatre briques devraient selon nous être assemblées pour constituer un dispositif efficace de prévention des escarres : (1) la présence d'un support optimisant la répartition des pressions de surface, (2) la mesure en continu de ces pressions de surface, (3) l'estimation des déformations internes aux tissus mous avec (4) la détection d'un risque d'escarre et l'envoi d'une alerte en direction de la personne. Cet article focalise sur les trois dernières briques qui restent à assembler pour construire un dispositif efficace de prévention des escarres

Dynamic biomechanical modelling for foot ulcer prevention.

International audienceThis paper introduces a 3D Dynamic Finite Element biomechanical model of the human foot used for diabetic foot pressure ulcer prevention. The model estimates the internal strains and send an alert to the user in case of high strains values

Biomechanical Lower Limb Model to Predict Patellar Position Alteration after Medial Open Wedge High Tibial Osteotomy

Medial open-wedge high tibial osteotomy is a surgical treatment for patients with a varus deformity and early-stage medial knee osteoarthritis. Observations suggest that this surgery can negatively affect the patellofemoral joint and change the patellofemoral kinematics. However, what causes these effects and how the correction angle can change the surgery's impact on the patellofemoral joint has not been investigated before. The objective of this study was to develop a biomechanical model that can predict the surgery's impact on the patellar position and find the correlation between the opening angles and the patellar position after the surgery. A combined finite element and multibody model of the lower limb was developed. The model's capabilities for predicting the patellofemoral kinematics were evaluated by performing a passive deep flexion simulation of the native knee and comparing the outcomes with magnetic resonance images of the study subject at various flexion angles. The model at a fixed knee flexion angle was then used to simulate the high tibial osteotomy surgery virtually. The results showed a correlation between the wedge opening angles and the patellar position in various degrees of freedom. These results indicate that larger wedge openings result in increased values of patellar distalization, lateral patellar shift, patellar rotation, and patellar internal tilt. The developed model in this study can be used in future studies to monitor the stress distribution on the patellar cartilage and connecting tissues to investigate their relationship with observations of pain and cartilage injury due to post-operative altered patellar kinematics

Pressure Ulcers and Dressings: A Strain Sensitivity Analysis of the Boundary Conditions of a Finite Element Model

Recently, a new bi-layer dressing was proposed by Urgo RID to reduce the healing time of pressure ulcers (PU). This dressing was numerically evaluated in previously published work. In the current work, the influence on the maximal shear strains of modelling parameters such as the dressing local geometry, the pressure applied by the gauze inside the wound, the wound deepness, and the mattress stiffness, was assessed. A sensitivity analysis was performed on these four parameters. Among all experiments, the mean maximal Green--Lagrange shear strain was 0.29. The gauze pressure explained 60% of the model response in terms of the volume of tissues under strains of 0.3, while the wound deepness explained 28%. The mattress had a significant, but low impact, whereas the dressing local geometry had no significant impact. As expected, the wound deepness was one of the most influential parameters. The gauze turned out to be more significant than expected. This may be explained by the large range of values chosen for this study. The results should be extended to more subjects, but still suggest that the gauze is a parameter that might not be neglected. Care should also be taken in clinical practice when using gauze that could have either a positive or negative impact on the soft tissues' strains. This may also depend on the wound deepness

Smart Diabetic Socks: Embedded device for diabetic foot prevention

1) Objectives Most foot ulcers are the consequence of a trauma (repetitive high stress, ill-fitting footwear, or an object inside the shoe) associated to diabetes. They are often followed by amputation and shorten life expectancy. This paper describes the prototype of the Smart Diabetic Socks that has been developed in the context of the French ANR TecSan project. The objective is to prevent pressure foot ulcers for diabetic persons. 2) Material and methods A fully wireless, customizable and washable "smart sock" has been designed. It is made of a textile which fibers are knitted in a way they provide measurements of the pressure exerted under and all around the foot in real-life conditions. This device is coupled with a subject-specific Finite Element foot model that simulates the internal strains within the soft tissues of the foot. 3) Results A number of derived stress indicators can be computed based on that analysis, such as the accumulated stress dose, high internal strains or peak pressures near bony prominences during gait. In case of risks for pressure ulcer, an alert is sent to the person and/or to the clinician. A watch, a smart-phone or a distant laptop can be used for providing such alert

Short-Term cost impact of compliance with clinical practice guidelines for initial sarcoma treatment

Background: The impact of compliance to clinical practice guidelines (CPG) on outcomes and/or costs of care has not been completely clarified.Objective: To estimate relationships between medical expenditures and compliance to CPG for initial sarcoma treatment.Research design: Selected cohorts of patients diagnosed with sarcoma in 2005 and 2006, and treated at the University hospital and/or the cancer centre of the Rhône-Alpes region, France (n=90). Main outcome measurements were: patient characteristics, compliance with CPG, health outcomes, and costs. Data were mainly extracted from patient records. The logarithm of treatment costs was modelled using linear and Tobit regressions.Results: Rates of compliance with CPG were 86%, 66%, 88%, 89%, and 95% for initial diagnosis, primary surgical excision, wide surgical excision, chemotherapy, and radiotherapy, respectively. Total average costs reached €24,439, with €1,784, €11,225, €10,360, and €1,016 for diagnosis, surgery (primary and wide surgical excisions), chemotherapy, and radiotherapy, respectively. Compliance of diagnosis with CPG decreased the cost of diagnosis, whereas compliance of primary surgical excision increased the cost of chemotherapy. Compliance of chemotherapy with CPG decreased the cost of radiotherapy.Conclusion: Since chemotherapy is one of the major cost drivers, these results support that compliance with guidelines increases medical care expenditures in short term.Oncology; Sarcoma; Cost; Clinical guidelines; Efficacy; Medical Practices; Government Policy; Regulation; Public Health

Hypersonic flows for reentry problems

INRIA and GAMNI/SMAI have organized a Workshop open to the international scientific community on hypersonic flows for reentry problems which was held in Palais des Congres d'Antibes in January 1990 (part I) and April 1991 (part II). This workshop was focussed on the issues of validation of numerical methodolies for the computation of high-Mach number flows, and gathered experts in Scientifical computing, fluid mechanics and experimentalists associated with the R and D Hermes program. Several volumes are devoted to the results and the detailed syntheses. This report presents a general synthesis of the motivations for this initiative, the development of the meetings, and the main conclusions drawn. A shorter version of this document has served as notes corresponding to a lecture given at an AGARD meeting