Detour and break optimising distance, a new perspective on transport and urbanism

International audienceFrom a discussion about the mathematical properties of metrics, we identify three fundamental characteristics of distance, which are optimality, detour and break. We then explore the implications of these properties for transport planning, urbanism and spatial planning. We state that distances contain the idea of optimum and that any distance is associated to a search for optimisation. Pedestrian movements obey this principle and sometimes depart from designed routes. Local sub-optimality conveyed by public transport maps has to be corrected by interventions on public space to relieve the load on central parts of networks. The second principle we state is that detour in distances is most often a means to optimise movement. Fast transport systems generates most of the detour observed in geographical spaces at regional scale. This is why detour has to be taken into account in regional transport policies. The third statement is that breaks in movement contribute to optimising distances. Benches, cafés, pieces of art, railway stations are examples of the urban break. These facilities of break represent an urban paradox: they organise the possibility of a break, of a waste of time in a trip, and they also contribute to optimising distances in a wider network. In that sense break should be considered as a relevant principle for the design of urban space in order to support a pedestrian oriented urban form

Le débit morphogène : un concept évolutif en lien avec les enjeux environnementaux

International audienc

Les lâchers morphogènes depuis un barrage justification opérationnelle et protocole d'intervention

International audience-Nous proposons une nouvelle approche méthodologique pour évaluer la pertinence et mettre en oeuvre des « lâchers morphogènes » en aval de barrages hydroélectriques. Ces lâchers correspondent à des débits relativement élevés lâchés par les barrages afin de générer des changements dans les caractéristiques physiques des lits fluviaux (par exemple, décolmatage, désensablement, élargissement des bandes actives alluviales, augmentation de la charge sédimentaire grossière, gestion de la végétation riveraine...) et de créer ou d'améliorer les habitats aquatiques et riverains. La méthodologie proposée repose sur une analyse de la littérature scientifique et sur nos propres expériences. Nous introduisons quelques méthodes de dimensionnement de ces lâchers (intensité, durée, forme de l'hydrogramme, variation saisonnière et récurrence), et évaluons les conflits potentiels avec divers enjeux environnementaux, socioéconomiques et opérationnels associés aux barrages. Nous proposons également des solutions alternatives lorsque ces lâchers ne peuvent être mis en oeuvre, du fait notamment de contraintes trop lourdes. La procédure d'évaluation et de mise en oeuvre des lâchers morphogènes se veut rigoureuse, itérative et basée sur plusieurs étapes, dont la plupart doivent être validées par les diverses parties prenantes : un diagnostic préliminaire quantifiable, la définition d'objectifs clairs, la prise en compte des contraintes présentes sur les sites, le dimensionnement du lâcher et sa mise en oeuvre. Une phase d'évaluation est également proposée pour tirer des leçons des expériences et améliorer les actions

From flushing flows to (eco)morphogenic releases: evolving terminology, practice, and integration into river management

International audienc

From flushing flows to (eco)morphogenic releases: evolving terminology, practice, and integration into river management

International audienc

Channel response to sediment replenishment in a large gravel-bed river: The case of the Saint-Sauveur dam in the Buech River (Southern Alps, France)

International audienceThe Saint-Sauveur dam was built in 1992 in the middle section of the Buech River. Downstream of the dam, a channel incision by several meters was observed. A gravel replenishment operation was planned in order to restore the active channel. An equivalent of two times the mean annual bedload-transport capacity (43,500 m(3)) was replenished downstream of the dam in September 2016. The aim of this paper is to quantify morphological change associated with sediment remobilization in order to evaluate the efficiency of the restoration works. The monitoring was based on a combination of (a) change detection using sequential high-resolution digital elevation models (from airborne LiDAR data), (b) bedload tracing using active ultrahigh-frequency radio-frequency identification technology, and (c) complementary field surveys of channel grain-size distribution and morphology for bedload-transport computation. Field monitoring allows us to capture a net aggradation along a 2-km reach after the first post-replenishment flood. A sediment balance analysis was performed to back-calculate bedload supply coming from the sluicing operation during the flood. Although the sediment replenishment operation clearly had a positive impact on the morphological conditions of the starved river reach, the effective bedload supply from artificial berms (22,650 m(3)) was insufficient to initiate substantial channel shifting along the restored reach and a subsequent amplification of the sediment recharge. The combination of high-resolution topographic resurveys and sediment tracing was successful to evaluate the downstream propagation of sediment replenishment effects

Malignant pleural mesothelioma with osteoblastic heterologous elements: CT and MR imaging findings

[DOI:\hrefhttps://dx.doi.org/10.2214/ajr.178.4.178094910.2214/ajr.178.4.1780949] [PubMed:\hrefhttps://www.ncbi.nlm.nih.gov/pubmed/1190688011906880

Accelerated coronary artery disease after heart transplantation: the role of enhanced platelet aggregation and thrombosis.

International audienceThe present study is a prospective examination of the relationship between platelet aggregation and the occurrence of graft failure in a single cohort of heart transplantation (HT) recipients. One-hundred-and-twenty-four patients underwent platelet function study and were then followed for 1 to 24 months (mean 6.7 months). There were nine re-transplantations and 13 deaths (11 related to ischaemic events, and two others). In 15 patients, pathologic examination confirmed or revealed that recent acute myocardial infarction was the obvious cause of the graft failure. In five patients, myocardial fibrosis related to severe and diffuse coronary disease was the only microscopic finding. In the last two patients, the cause of the heart failure was not clearly identified. In recent myocardial infarction there was a high incidence (14/15) of coronary thrombi. Thrombi were multiple, disseminated in the coronary tree end of different age. Their presence at autopsy or after explantation was associated with an enhanced ex vivo platelet aggregability as compared with patients without coronary thrombi (n = 8): 43.3 +/- 1.7% of maximal aggregation vs. 34.4 +/- 2.4 (P = 0.006) and 48.4 +/- 5.2 vs. 22.6 +/- 4.9 (P = 0.003) for the primary and secondary waves of ADP-induced aggregation. These results suggest that thrombosis and platelets may play a major role in the process of accelerated coronary artery disease after HT

[Value of coronary angiography in the diagnosis of coronary artery disease of the transplanted heart. Coronary angiography and arteriosclerosis of the graft]

International audienceThe diagnostic value of coronary angiography, a widespread method of detection of transplant coronary artery disease, was studied in 17 cardiac transplant patients with reference to histological examination. In the 6 coronary segments studied, the only significant but weak correlation that was found was for the distal left anterior descending artery: the correlations were not statistically significant in the other 5 segments. Coronary angiography underestimated lesions and false negative results were frequently reported (66 and 27% respectively). The limitations of coronary angiography may be explained by the technical artefacts related to both methods of evaluation and the anatomically diffuse and distal nature of transplant coronary artery atherosclerosis. A more reliable diagnostic method would seem to be required in view of the clinical importance of this pathology