How to Handle Concomitant Asymptomatic Prosthetic Joints During an Episode of Hematogenous Periprosthetic Joint Infection:a Multicenter Analysis

BACKGROUND: Prosthetic joints are at risk of becoming infected during an episode of bacteremia, especially during Staphylocococcus aureus bacteremia. However, it is unclear how often asymptomatic periprosthetic joint infection (PJI) occurs, and whether additional diagnostics should be considered. METHODS: In this multicenter study, we retrospectively analyzed a cohort of patients with a late acute (hematogenous) PJI between 2005-2015 who had concomitant prosthetic joints in situ. Patients without at least 1 year of follow-up were excluded. RESULTS: We included 91 patients with a hematogenous PJI and 108 concomitant prosthetic joints. The incident PJI was most frequently caused by Staphylococcus aureus (43%), followed by streptococci (26%) and Gram-negative rods (18%). Of 108 concomitant prosthetic joints, 13 were symptomatic, of which 10 were subsequently diagnosed as a second PJI. Of the 95 asymptomatic prosthetic joints, 1 PJI developed during the follow-up period and was classified as a "missed" PJI at the time of bacteremia with S. aureus (1.1%). Infected prosthetic joints were younger than the noninfected ones in 67% of cases, and prosthetic knees were affected more often than prosthetic hips (78%). CONCLUSIONS: During an episode of hematogenous PJI, concomitant asymptomatic prosthetic joints have a very low risk of being infected, and additional diagnostic work-up for these joints is not necessary

Combining farmers' decision rules and landscape stochastic regularities for landscape modelling

International audienceLandscape spatial organization (LSO) strongly impacts many environmental issues. Modelling agricultural landscapes and describing meaningful landscape patterns are thus regarded as key-issues for designing sustainable landscapes. Agricultural landscapes are mostly designed by farmers. Their decisions dealing with crop choices and crop allocation to land can be generic and result in landscape regularities, which determine LSO. This paper comes within the emerging discipline called "landscape agronomy", aiming at studying the organization of farming practices at the landscape scale. We here aim at articulating the farm and the landscape scales for landscape modelling. To do so, we develop an original approach consisting in the combination of two methods used separately so far: the identification of explicit farmer decision rules through on-farm surveys methods and the identification of landscape stochastic regularities through data-mining. We applied this approach to the Niort plain landscape in France. Results show that generic farmer decision rules dealing with sunflower or maize area and location within landscapes are consistent with spatiotemporal regularities identified at the landscape scale. It results in a segmentation of the landscape, based on both its spatial and temporal organization and partly explained by generic farmer decision rules. This consistency between results points out that the two modelling methods aid one another for land-use modelling at landscape scale and for understanding the driving forces of its spatial organization. Despite some remaining challenges, our study in landscape agronomy accounts for both spatial and temporal dimensions of crop allocation: it allows the drawing of new spatial patterns coherent with land-use dynamics at the landscape scale, which improves the links to the scale of ecological processes and therefore contributes to landscape ecology.L'organisation du paysage influe sur les problèmes environnementaux. Modéliser les paysages pour les décrire à l'aide de formes significatives est une étage clé. Les paysages agricoles sont principalement construits par les agriculteurs dont les décision d'assolement peuvent être génériques et déterminer des régularités dans l'organisation du paysage. Cet article contribue à l'agronomie des paysage qui est une discipline émergente. Nous cherchons à articuler les échelles du paysage et de l'exploitation agricole en développant deux méthodes : l'une consiste à identifier les décisions des agriculteurs par le bais d'enquêtes, l'autre consiste à retrouver des régularités stochastiques dans le paysage par le bais de fouille de données. Nous avons appliqué cette approche au paysage de la plaine de Niort en France. Les résultats montrent que les décisions des agriculteurs en matière de tournesol et maïs sont génériques et ont des effets sur le paysages que des méthodes de fouille de données révèlent et quantifient

Prospective : l'eau et les milieux aquatiques: Enjeux de sociétés et défis pour la recherche

National audienc

En guise de conclusion

Sébillotte Jean, Cochet J.-C. En guise de conclusion. In: Économie rurale. N°93, 1972. Les concepts et les méthodes d'établissement du revenu agricole et des revenus des agriculteurs. pp. 111-113

Elaboration du rendement du ble dur en conditions semi-arides en Tunisie : relations entre composantes du rendement sous differents regimes de nutrition azotee et hydrique

National audienceWe studied the yield components of durum wheat (Triticum durum Desf) under semi-arid conditions in Tunisia (fig 1). The relationships between several yield components were established in conditions where nitrogen and water were unlikely to be limiting. The level of each component was fitted to that of components determined during previous periods of the crop cycle. Resulting relationships were considered as describing the maximum values of each component. They were plotted together with coupled values of components observed in conditions where water or nitrogen could be limiting. This allowed diagnosis of the effects of varying levels of nitrogen and water supplies on each yield component. The experiments were carried out in two soils ("Tell" and "Hamri", see table II) and several levels of nitrogen fertilization (fig 2), for two years with contrasting rainfall. The relationships between yield components, observed in the wet year and for high levels of nitrogen supply had similar patterns compared with those established for wheat grown in temperate regions (table I). However, the values of fitted parameters (table III) were appreciably different. In "Tell" soil, the maximum levels of all yield components were reached during the wet year for nitrogen fertilization as low as 60 kg ha-1 applied at tillering and beginning of the stem elongation; in "Hamri" soil, the maximum levels could not be reached, even for a total nitrogen amount of 100 kg ha-1 yield components had very low levels during the dry year in the two soils, with no appreciable effect of fertilization (table IV). In both dry and wet years, yields correlated better with the number of kernels per m2 (fig 3) than with the kernel weight. This suggests that pre-anthesis environmental conditions had a overriding effect on yields (figs 4 and 5). The observed range of kernel weight was not large enough to induce high variations in yield, in spite of the wide range of water and nitrogen supply. We used these results to propose a way of deciding nitrogen fertilization in relationship with yield objective in wet conditions (table V).L’élaboration du rendement du blé dur en climat semi-aride tunisien est étudiée afin de disposer de références permettant le diagnostic de facteurs limitants au champ. On teste sur blé dur les relations entre composantes du rendement établies sur blé tendre en climat tempéré. En conditions où seuls la température et le rayonnement intercepté sont limitants, on obtient, sur blé dur, des relations analogues à celles établies sur blé tendre. Le paramétrage de ces relations est ici proposé. Le comportement du blé dur en conditions variables de nutrition azotée et hydrique au cours de 2 années de climat contrasté est étudié en utilisant les modèles préalables comme outils de diagnostic. Dans tous les cas, la principale composante liée au rendement est le nombre de grains par m2, qui dépend des conditions de croissance et de développement pendant la phase semis-floraison. La composante «poids d’un grain» est cependant affectée par les conditions d’alimentation hydrique, à travers la durée de la phase de remplissage du grain. On met en évidence en année humide l’influence du fractionnement de l’azote apporté sur plusieurs composantes du rendement. Une première formulation de références techniques sur la fertilisation azotée en conditions hydriques favorables est proposée et discutée

Élaboration du rendement du blé dur en conditions semi-arides en Tunisie : relations entre composantes du rendement sous différents régimes de nutrition azotée et hydrique

L'élaboration du rendement du blé dur en climat semi-aride tunisien est étudiée afin de disposer de références permettant le diagnostic de facteurs limitants au champ. On teste sur blé dur les relations entre composantes du rendement établies sur blé tendre en climat tempéré. En conditions où seuls la température et le rayonnement intercepté sont limitants, on obtient, sur blé dur, des relations analogues à celles établies sur blé tendre. Le paramétrage de ces relations est ici proposé. Le comportement du blé dur en conditions variables de nutrition azotée et hydrique au cours de 2 années de climat contrasté est étudié en utilisant les modèles préalables comme outils de diagnostic. Dans tous les cas, la principale composante liée au rendement est le nombre de grains par m2, qui dépend des conditions de croissance et de développement pendant la phase semis-floraison. La composante «poids d'un grain» est cependant affectée par les conditions d'alimentation hydrique, à travers la durée de la phase de remplissage du grain. On met en évidence en année humide l'influence du fractionnement de l'azote apporté sur plusieurs composantes du rendement. Une première formulation de références techniques sur la fertilisation azotée en conditions hydriques favorables est proposée et discutée.Analysis of yield components to diagnose limiting factors of durum wheat yield in semi-arid conditions: relationships under various water and nitrogen supplies. We studied the yield components of durum wheat (Triticum durum Desf) under semi-arid conditions in Tunisia (fig 1). The relationships between several yield components were established in conditions where nitrogen and water were unlikely to be limiting. The level of each component was fitted to that of components determined during previous periods of the crop cycle. Resulting relationships were considered as describing the maximum values of each component. They were plotted together with coupled values of components observed in conditions where water or nitrogen could be limiting. This allowed diagnosis of the effects of varying levels of nitrogen and water supplies on each yield component. The experiments were carried out in two soils ("Tell" and "Hamri", see table II) and several levels of nitrogen fertilization (fig 2), for two years with contrasting rainfall. The relationships between yield components, observed in the wet year and for high levels of nitrogen supply had similar patterns compared with those established for wheat grown in temperate regions (table I). However, the values of fitted parameters (table III) were appreciably different. In "Tell" soil, the maximum levels of all yield components were reached during the wet year for nitrogen fertilization as low as 60 kg ha-1, applied at tillering and beginning of the stem elongation; in "Hamri" soil, the maximum levels could not be reached, even for a total nitrogen amount of 100 kg ha-1; yield components had very low levels during the dry year in the two soils, with no appreciable effect of fertilization (table IV). In both dry and wet years, yields correlated better with the number of kernels per m2 (fig 3) than with the kernel weight. This suggests that pre-anthesis environmental conditions had a overriding effect on yields (figs 4 and 5). The observed range of kernel weight was not large enough to induce high variations in yield, in spite of the wide range of water and nitrogen supply. We used these results to propose a way of deciding nitrogen fertilization in relationship with yield objective in wet conditions (table V)