Modelling waving crops using large-eddy simulation: Comparison with experiments and a linear stability analysis

International audienceIn order to investigate the possibility of modelling plant motion at the landscape scale, an equation for crop plant motion, forced by an instantaneous velocity field, is introduced in a large-eddy simulation (LES) airflow model, previously validated over homogeneous and heterogeneous canopies. The canopy is simply represented as a poroelastic continuous medium, which is similar in its discrete form to an infinite row of identical oscillating stems. Only one linear mode of plant vibration is considered. Two-way coupling between plant motion and the wind flow is insured through the drag force term. The coupled model is validated on the basis of a comparison with measured movements of an alfalfa crop canopy. It is also compared with the outputs of a linear stability analysis. The model is shown to reproduce the well-known phenomenon of honami which is typical of wave-like crop motions on windy days. The wavelength of the main coherent waving patches, extracted using a bi-orthogonal decomposition (BOD) of the crop velocity fields, is in agreement with that deduced from video recordings. The main spatial and temporal characteristics of these waving patches exhibit the same variation with mean wind velocity as that observed with the measurements. However they differ from the coherent eddy structures of the wind flow at canopy top, so that coherent waving patches cannot be seen as direct signatures of coherent eddy structures. Finally, it is shown that the impact of crop motion on the wind dynamics is negligible for current wind speed values. No lock-in mechanism of coherent eddy structures on plant motion is observed, in contradiction with the linear stability analysis. This discrepancy may be attributed to the presence of a nonlinear saturation mechanism in LES. © 2010 Cambridge University Press

Médecin ou comédien : analyse de l'acquisition et de l'emploi du rôle dans voyage au bout de la nuit de Céline

Ma recherche est une analyse de la fonction de médecin qu'occupe le narrateur du roman de Céline : Voyage au bout de la nuit. Bien qu'on ne puisse ignorer la profession médicale du personnage de Bardamu, le choix de celle-ci plutôt qu'une autre laisse planer quelques questions qui ont nourri ma curiosité. L'introduction explique le pourquoi d'un tel questionnement après avoir fait un bref résumé du récit. Elle indique aussi le choix de la théorie d'Erving Goffman qui a servi à l'analyse et a permis de mieux saisir le fonctionnement du rôle de médecin. Le premier chapitre fait un survol des travaux du sociologue en énumérant quelques outils de base qui ont été utilisés au cours du travail. Le deuxième chapitre montre comment Bardamu, à travers une multitude d'expériences et d'observations, développe une attitude particulière envers l'existence et comment celle-ci influence les choix à venir. Ainsi, je passe en revue les trois étapes de son périple autour du monde, soit la guerre, l'Afrique et l'Amérique, et je montre comment chacun de ces moments participe à l'acquisition d'un rôle ultérieur. J'analyse donc chaque événement en fonction du rôle de médecin à venir et des caractéristiques singulières qu'il présente. Le troisième chapitre utilise la théorie de Goffman pour voir comment Bardamu, une fois le rôle adopté, l'utilise, en demeurant toujours en lien étroit avec les quelques idées dégagées du premier chapitre. Se déployant aussi sur trois parties, le chapitre aborde la figure de médecin sur trois tableaux : le médecin de banlieue à la Garenne-Rancy; le médecin mêlé à l'intimité de la famille Henrouille; et le médecin travaillant au sein d'une équipe de collègues dans une institution. La conclusion revient sur les principales particularités du personnage de Bardamu et de son rôle tout en montrant comment celles-ci parviennent à rendre à l'acteur une certaine distinction par rapport à son rôle

Caractérisation des canaux AmNav1, AmNav2 et VdNav1 : nouvelles méthodes pour évaluer la toxicité d'insecticides

Tableau d'honneur de la Faculté des études supérieures et postdoctorales, 2016-2017.Les canaux sodiques dépendants du voltage (NaV) participent à la genèse et la transmission de l'influx nerveux via l'initiation du potentiel d'action. Chez l'insecte, ces protéines sont la cible de nombreux insecticides neurotoxiques. Étant donné le déclin des populations d'insectes pollinisateurs observé récemment, il devient désormais important d'avoir des méthodes permettant le développement d'insecticides qui ne ciblent pas les pollinisateurs. L'objectif général de ma thèse a donc été de mettre au point des méthodes in-vitro et insilico pouvant être appliquées à grande échelle dans le but d'évaluer le risque potentiel que certains insecticides pourraient représenter pour l'abeille. Pour ce faire, nous avons procédé à la caractérisation biophysique et pharmacologique des canaux sodiques NaV1 et NaV2 d'abeille. Nous avons aussi créé un modèle moléculaire du canal NaV1 d'abeille permettant la conception rationnelle d'insecticides. De plus, nous avons caractérisé le canal NaV1 de Varroa destructor, un parasite important de l'abeille. Les études insérées dans cette thèse ont permis de démontrer que le canal NaV2 n'est pas une cible secondaire des insecticides pyréthroïdes. De plus, nous avons pu mesurer les effets et l'affinité d'insecticides sur leur cible moléculaire chez l'abeille suite à l'expression du canal NaV1 d'abeille en ovocyte de grenouille. Cela permet le criblage de composé à haut débit afin de sélectionner des composés représentant un faible risque pour l'abeille. De même, l'expression du canal NaV1 de Varroa destructor en système d'expression hétérologue permettrait l'utilisation de la méthode de criblage de composés à haut débit dans le but d'identifier des insecticides qui représentent un risque important pour cette peste. D'ailleurs, nous avons déterminé que le fluvalinate, un insecticide pyréthroïde utilisé pour contrôler les populations de Varroa destructor dans les ruches d'abeille, a une affinité différente pour le canal NaV1 d'abeille que pour celui de Varroa destructor. Cela indique une différence dans les sites de liaisons du composé qui pourrait éventuellement être exploitée. Mes travaux ouvrent donc la voie au développement de composés ciblant davantage des animaux nuisibles comme le Varroa destructor que des animaux utiles comme l'abeille. De plus, les caractérisations effectuées pourraient être utiles pour des études centrées sur les rôles et l'évolution des canaux ioniques appartenant aux familles NaV et CaV.Voltage-gated sodium channels (NaV) are implicated in the genesis and transmission of action potentials. In insects, these proteins are the target of a number of neurotoxic insecticides. In the background of the pollinator decline observed recently, it has become necessary to develop insecticides which do not target beneficial insects such as bees. The main objective of my thesis was to develop in-vitro and in-silico methods which could be used on a large scale to evaluate the risk associated with the use of certain compounds for bees. To do so, we assessed the biophysical and pharmacological properties of the honeybee's NaV1 and NaV2 channels. We also created a molecular model for the NaV1 channel which enables the rational design of insecticides. Furthermore, we have characterized the Varroa destructor NaV1 channels. The investigations featured in this thesis demonstrate that the NaV2 channel is not a secondary target of pyrethroïd insecticides. However, following expression in frog oocytes, it is possible to quantify the effects and affinity of those insecticides for their molecular target in the honeybee, the NaV1 channel. This makes possible the use of high throughput screening technologies for the selection of insecticides which would represent a small risk for bees. Moreover, the expression of Varroa destructor NaV1 channels in frog oocytes enables the use of medium throughput screening technologies to identify compounds which could be deleterious for this pest. Indeed, we determined that fluvalinate, a pyrethroïd insecticide used to control Varroa population in honeybee hives, has an affinity for the honeybee NaV1 channel that is different than that for the Varroa channel. This indicates that the binding site of this compound on the Varroa channel would differ from the binding site on the bee channel. This difference could be exploited to improve the specificity of fluvalinate. The work presented here represents a first step in the development of methods which could be used to decrease the toxicity of insecticides for bees while increasing their specificity of against pests such as Varroa destructor. Furthermore, the characterizations performed provide new insights on topics such as the roles and the evolution of NaV et CaV channels

Statistical ecology comes of age

The desire to predict the consequences of global environmental change has been the driver towards more realistic models embracing the variability and uncertainties inherent in ecology. Statistical ecology has gelled over the past decade as a discipline that moves away from describing patterns towards modelling the ecological processes that generate these patterns. Following the fourth International Statistical Ecology Conference (1-4 July 2014) in Montpellier, France, we analyse current trends in statistical ecology. Important advances in the analysis of individual movement, and in the modelling of population dynamics and species distributions, are made possible by the increasing use of hierarchical and hidden process models. Exciting research perspectives include the development of methods to interpret citizen science data and of efficient, flexible computational algorithms for model fitting. Statistical ecology has come of age: it now provides a general and mathematically rigorous framework linking ecological theory and empirical data.Peer reviewe

A Review of National-Level Adaptation Planning with Regards to the Risks Posed by Climate Change on Infectious Diseases in 14 OECD Nations

Climate change is likely to have significant implications for human health, particularly through alterations of the incidence, prevalence, and distribution of infectious diseases. In the context of these risks, governments in high income nations have begun developing strategies to reduce potential climate change impacts and increase health system resilience (i.e., adaptation). In this paper, we review and evaluate national-level adaptation planning in relation to infectious disease risks in 14 OECD countries with respect to “best practices” for adaptation identified in peer-reviewed literature. We find a number of limitations to current planning, including negligible consideration of the needs of vulnerable population groups, limited emphasis on local risks, and inadequate attention to implementation logistics, such as available funding and timelines for evaluation. The nature of planning documents varies widely between nations, four of which currently lack adaptation plans. In those countries where planning documents were available, adaptations were mainstreamed into existing public health programs, and prioritized a sectoral, rather than multidisciplinary, approach. The findings are consistent with other scholarship examining adaptation planning indicating an ad hoc and fragmented process, and support the need for enhanced attention to adaptation to infectious disease risks in public health policy at a national level

A Proton Leak Current through the Cardiac Sodium Channel Is Linked to Mixed Arrhythmia and the Dilated Cardiomyopathy Phenotype

Cardiac Na+ channels encoded by the SCN5A gene are essential for initiating heart beats and maintaining a regular heart rhythm. Mutations in these channels have recently been associated with atrial fibrillation, ventricular arrhythmias, conduction disorders, and dilated cardiomyopathy (DCM)

Global, regional, and national disability-adjusted life-years (DALYs) for 333 diseases and injuries and healthy life expectancy (HALE) for 195 countries and territories, 1990–2016: a systematic analysis for the Global Burden of Disease Study 2016

BACKGROUND: Measurement of changes in health across locations is useful to compare and contrast changing epidemiological patterns against health system performance and identify specific needs for resource allocation in research, policy development, and programme decision making. Using the Global Burden of Diseases, Injuries, and Risk Factors Study 2016, we drew from two widely used summary measures to monitor such changes in population health: disability-adjusted life-years (DALYs) and healthy life expectancy (HALE). We used these measures to track trends and benchmark progress compared with expected trends on the basis of the Socio-demographic Index (SDI). METHODS: We used results from the Global Burden of Diseases, Injuries, and Risk Factors Study 2016 for all-cause mortality, cause-specific mortality, and non-fatal disease burden to derive HALE and DALYs by sex for 195 countries and territories from 1990 to 2016. We calculated DALYs by summing years of life lost and years of life lived with disability for each location, age group, sex, and year. We estimated HALE using age-specific death rates and years of life lived with disability per capita. We explored how DALYs and HALE differed from expected trends when compared with the SDI: the geometric mean of income per person, educational attainment in the population older than age 15 years, and total fertility rate. FINDINGS: The highest globally observed HALE at birth for both women and men was in Singapore, at 75·2 years (95% uncertainty interval 71·9-78·6) for females and 72·0 years (68·8-75·1) for males. The lowest for females was in the Central African Republic (45·6 years [42·0-49·5]) and for males was in Lesotho (41·5 years [39·0-44·0]). From 1990 to 2016, global HALE increased by an average of 6·24 years (5·97-6·48) for both sexes combined. Global HALE increased by 6·04 years (5·74-6·27) for males and 6·49 years (6·08-6·77) for females, whereas HALE at age 65 years increased by 1·78 years (1·61-1·93) for males and 1·96 years (1·69-2·13) for females. Total global DALYs remained largely unchanged from 1990 to 2016 (-2·3% [-5·9 to 0·9]), with decreases in communicable, maternal, neonatal, and nutritional (CMNN) disease DALYs offset by increased DALYs due to non-communicable diseases (NCDs). The exemplars, calculated as the five lowest ratios of observed to expected age-standardised DALY rates in 2016, were Nicaragua, Costa Rica, the Maldives, Peru, and Israel. The leading three causes of DALYs globally were ischaemic heart disease, cerebrovascular disease, and lower respiratory infections, comprising 16·1% of all DALYs. Total DALYs and age-standardised DALY rates due to most CMNN causes decreased from 1990 to 2016. Conversely, the total DALY burden rose for most NCDs; however, age-standardised DALY rates due to NCDs declined globally. INTERPRETATION: At a global level, DALYs and HALE continue to show improvements. At the same time, we observe that many populations are facing growing functional health loss. Rising SDI was associated with increases in cumulative years of life lived with disability and decreases in CMNN DALYs offset by increased NCD DALYs. Relative compression of morbidity highlights the importance of continued health interventions, which has changed in most locations in pace with the gross domestic product per person, education, and family planning. The analysis of DALYs and HALE and their relationship to SDI represents a robust framework with which to benchmark location-specific health performance. Country-specific drivers of disease burden, particularly for causes with higher-than-expected DALYs, should inform health policies, health system improvement initiatives, targeted prevention efforts, and development assistance for health, including financial and research investments for all countries, regardless of their level of sociodemographic development. The presence of countries that substantially outperform others suggests the need for increased scrutiny for proven examples of best practices, which can help to extend gains, whereas the presence of underperforming countries suggests the need for devotion of extra attention to health systems that need more robust support. FUNDING: Bill & Melinda Gates Foundation

Hyperoxemia and excess oxygen use in early acute respiratory distress syndrome: insights from the LUNG SAFE study

Contains fulltext : 218568.pdf (publisher's version ) (Open Access)BACKGROUND: Concerns exist regarding the prevalence and impact of unnecessary oxygen use in patients with acute respiratory distress syndrome (ARDS). We examined this issue in patients with ARDS enrolled in the Large observational study to UNderstand the Global impact of Severe Acute respiratory FailurE (LUNG SAFE) study. METHODS: In this secondary analysis of the LUNG SAFE study, we wished to determine the prevalence and the outcomes associated with hyperoxemia on day 1, sustained hyperoxemia, and excessive oxygen use in patients with early ARDS. Patients who fulfilled criteria of ARDS on day 1 and day 2 of acute hypoxemic respiratory failure were categorized based on the presence of hyperoxemia (PaO2 > 100 mmHg) on day 1, sustained (i.e., present on day 1 and day 2) hyperoxemia, or excessive oxygen use (FIO2 >/= 0.60 during hyperoxemia). RESULTS: Of 2005 patients that met the inclusion criteria, 131 (6.5%) were hypoxemic (PaO2 < 55 mmHg), 607 (30%) had hyperoxemia on day 1, and 250 (12%) had sustained hyperoxemia. Excess FIO2 use occurred in 400 (66%) out of 607 patients with hyperoxemia. Excess FIO2 use decreased from day 1 to day 2 of ARDS, with most hyperoxemic patients on day 2 receiving relatively low FIO2. Multivariate analyses found no independent relationship between day 1 hyperoxemia, sustained hyperoxemia, or excess FIO2 use and adverse clinical outcomes. Mortality was 42% in patients with excess FIO2 use, compared to 39% in a propensity-matched sample of normoxemic (PaO2 55-100 mmHg) patients (P = 0.47). CONCLUSIONS: Hyperoxemia and excess oxygen use are both prevalent in early ARDS but are most often non-sustained. No relationship was found between hyperoxemia or excessive oxygen use and patient outcome in this cohort. TRIAL REGISTRATION: LUNG-SAFE is registered with ClinicalTrials.gov, NCT02010073

Global, regional, and national disability-adjusted life-years (DALYs) for 333 diseases and injuries and healthy life expectancy (HALE) for 195 countries and territories, 1990-2016:a systematic analysis for the Global Burden of Disease Study 2016

BACKGROUND: Measurement of changes in health across locations is useful to compare and contrast changing epidemiological patterns against health system performance and identify specific needs for resource allocation in research, policy development, and programme decision making. Using the Global Burden of Diseases, Injuries, and Risk Factors Study 2016, we drew from two widely used summary measures to monitor such changes in population health: disability-adjusted life-years (DALYs) and healthy life expectancy (HALE). We used these measures to track trends and benchmark progress compared with expected trends on the basis of the Socio-demographic Index (SDI).METHODS: We used results from the Global Burden of Diseases, Injuries, and Risk Factors Study 2016 for all-cause mortality, cause-specific mortality, and non-fatal disease burden to derive HALE and DALYs by sex for 195 countries and territories from 1990 to 2016. We calculated DALYs by summing years of life lost and years of life lived with disability for each location, age group, sex, and year. We estimated HALE using age-specific death rates and years of life lived with disability per capita. We explored how DALYs and HALE differed from expected trends when compared with the SDI: the geometric mean of income per person, educational attainment in the population older than age 15 years, and total fertility rate.FINDINGS: The highest globally observed HALE at birth for both women and men was in Singapore, at 75·2 years (95% uncertainty interval 71·9-78·6) for females and 72·0 years (68·8-75·1) for males. The lowest for females was in the Central African Republic (45·6 years [42·0-49·5]) and for males was in Lesotho (41·5 years [39·0-44·0]). From 1990 to 2016, global HALE increased by an average of 6·24 years (5·97-6·48) for both sexes combined. Global HALE increased by 6·04 years (5·74-6·27) for males and 6·49 years (6·08-6·77) for females, whereas HALE at age 65 years increased by 1·78 years (1·61-1·93) for males and 1·96 years (1·69-2·13) for females. Total global DALYs remained largely unchanged from 1990 to 2016 (-2·3% [-5·9 to 0·9]), with decreases in communicable, maternal, neonatal, and nutritional (CMNN) disease DALYs offset by increased DALYs due to non-communicable diseases (NCDs). The exemplars, calculated as the five lowest ratios of observed to expected age-standardised DALY rates in 2016, were Nicaragua, Costa Rica, the Maldives, Peru, and Israel. The leading three causes of DALYs globally were ischaemic heart disease, cerebrovascular disease, and lower respiratory infections, comprising 16·1% of all DALYs. Total DALYs and age-standardised DALY rates due to most CMNN causes decreased from 1990 to 2016. Conversely, the total DALY burden rose for most NCDs; however, age-standardised DALY rates due to NCDs declined globally.INTERPRETATION: At a global level, DALYs and HALE continue to show improvements. At the same time, we observe that many populations are facing growing functional health loss. Rising SDI was associated with increases in cumulative years of life lived with disability and decreases in CMNN DALYs offset by increased NCD DALYs. Relative compression of morbidity highlights the importance of continued health interventions, which has changed in most locations in pace with the gross domestic product per person, education, and family planning. The analysis of DALYs and HALE and their relationship to SDI represents a robust framework with which to benchmark location-specific health performance. Country-specific drivers of disease burden, particularly for causes with higher-than-expected DALYs, should inform health policies, health system improvement initiatives, targeted prevention efforts, and development assistance for health, including financial and research investments for all countries, regardless of their level of sociodemographic development. The presence of countries that substantially outperform others suggests the need for increased scrutiny for proven examples of best practices, which can help to extend gains, whereas the presence of underperforming countries suggests the need for devotion of extra attention to health systems that need more robust support.FUNDING: Bill &amp; Melinda Gates Foundation.</p