L'espace communal, essai de modélisation

La modélisation spatiale appliquée à un espace communal (Châtillon, Hauts-de- Seine) permet d'identifier un secteur sensible qui nécessiterait un aménagement spécifique

The adjustment and monitoring of freeform surfaces using inertial tolerancing.

International audienceAt present, the manufacturing process allows one to make parts easily having one or several freeform surfaces thanks to the numerical link between Computer Aided Design (CAD) and Computer Numerical Control (CNC). Indeed, from a part defined by a CAD software the designer realizes the program of the CNC and can produce, if the CNC is supplied. However, during the step of production, the operator meets some difficulties to monitor and control. Indeed the ISO tolerancing of this kind of part is often complex and the setting of the manufacturer process is complex to adjust a part to its target values (numerical model). In this paper, we propose an original approach which simplifies the monitoring of freeform surface. We introduce this approach, we present the concept and we conclude by two industrial cases

Impact des terrils houillers sur la qualité des eaux souterraines (bassin minier Nord-Pas-de-Calais, France) : approche géochimique et isotopique

L'exploitation du charbon dans le Nord-Pas-de-Calais (France) a engendré le dépôt d'importantes quantités de résidus miniers sous forme de terrils, essentiellement constitués de schistes houillers. Le lessivage de ces stériles par les eaux météoriques et l'oxydation des sulfures de fer contenus sont susceptibles de contribuer à l'enrichissement en sulfates et métaux associés de l'aquifère de la craie, principale ressource en eau de la région. Des analyses chimiques et isotopiques (S & C) ont été effectuées sur des prélèvements d'eau en amont et en aval hydraulique des sites d'étude ainsi que sur la fraction minérale des terrils. Afin de déterminer les modalités d'infiltration des eaux météoriques au sein des terrils, des prospections radio-magnétotelluriques, couplées à des mesures de perméabilité et de granularité ont été effectuées. Les analyses ont permis de mettre en évidence que le lessivage des terrils entraîne un flux d'ions sulfate et de carbone vers l'aquifère de la craie. L'approche géophysique a permis de mettre en évidence un phénomène d'infiltration des eaux météoriques. Elle a montré en outre l'existence de barrières de perméabilité en profondeur. Il apparaît donc que les eaux météoriques, lorsqu'elles s'infiltrent dans le terril, ne peuvent pénétrer à plus de quelques mètres de profondeur. L'existence de zones imperméables, en limitant l'infiltration des eaux en profondeur, limite également la quantité de sulfure potentiellement oxydable et donc la quantité de sulfates entraînée vers l'aquifère de la craie.In the Nord-Pas-de-Calais region (France), coal mining activity has induced a build-up of many mine tips. The tip materials are dominantly composed of siltstones, locally rich in iron sulfide. Weathering of pyrite might be expected to release sulfate ions and associated metals within the run-off waters down to the underlying aquifer, which is composed of a thick Cretaceous chalk formation. The objectives of this study were twofold: (1) to determine the possible role of the mine tips in the sulfate mineralization of the chalk aquifer and; (2) to assess the amount of waste material that can be leached and may supply sulfate ions to the water table.Two sites were selected for this study. Site 1 rests directly on the Senonian-Turonian chalk, whereas site 2 lies on sandy-clayey Cenozoic formations overlying the chalk formations (Figs. 1-2). Water samples were collected within the chalk aquifer (Fig. 3), which represents a free water table except for where the almost impermeable Cenozoic formations confine this table (site 2). Rock samples were collected at the surface and at a depth of <12 m at both sites. Various analyses were performed on these samples including mineralogical analyses carried out on both the bulk fraction and the clayey fraction, as well as elementary analyses of total carbon, total sulfur and CaCO3 contents. Elemental analyses were carried out by Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES: major and minor elements) or Inductively Coupled Plasma-Mass Spectrometry (ICP-MS: trace elements). Chemical and isotopic (C, S) analyses were performed on water sampled from upstream and downstream of the mine tips. In situ measurements were also carried out during sampling. Finally, to assess the degree of rainwater seeping through the coal mine tips, two radio-magnetotelluric surveys were carried out in September and November, 1999 following rainy periods. Permeability measurements and grain-size analyses of subsurface samples were also performed at site 2.The carbon and sulfur contents showed superficial leaching on the mine tips (Fig. 4). The use of sulfur isotopes as tracers of the sulfate origin allowed identification of two sources for the two sites: a "mine tip" source with a slightly negative d34 S (-2.8‰ to -3.9‰), which corresponds to the oxidation of sulfides contained by the Carboniferous shales, and another source (d34 S=-20‰) corresponding to the gypsum of the Cenozoic formations, which was only present at site 2 (Figs. 5 & 6).This study outlined different behavior for the tips of the two sites. At site 1, where there is a free water-table zone, the mine tip leachates carry sulfate ions directly to the water table, whereas in the case of a confined aquifer zone such as the one present at site 2, a proportion of the sulfate was reduced once exported to the water table (the redox potential showed negative values; Table 1). This suggestion of bacterially-mediated reduction is supported by the d34 S of the sulfate content in the water table. The bacterial activity was fueled by the organic carbon release that accompanies the sulfur leaching on the mine tips. This carbon contribution was confirmed by the 14C activity that characterized the chalk aquifer waters at the upstream region of the mine tip and noticeably decreased downstream. The decrease is a result of the supply of "dead carbon" from the mine tips (Fig. 7).The oxidation of pyrite also results in H+ production. However, the pH decrease observed downstream from the sites was very slight. Waters derived from leaching of the mine tip seeped through the buffered environment of the chalk aquifer. The distribution of metal content showed no surface to depth gradient for samples taken from both sites. The only evidence of "neutral acid mining drainage" (NAMD) was the sulfate amounts exported, and the increase in Mg, Ca, HCO3- and Sr contents observed downstream from the sites (Table 2a-b).The decrease in the apparent resistivity of radio-magnetotelluric profiles demonstrated that rain waters could deeply penetrate in some parts of the tip at site 2 (Fig. 9). Considering the constant nature of the waste material (grain size and porosity), a decrease in resistivity accompanied by an increase in conductivity between the two surveys indicated water seepage. Permeability measurements showed the occurrence of deep permeability barriers (Fig. 10), limiting not only rainwater seepage, but also the amount of mobilizable sulfide and consequently the amount of sulfates exported to the chalk aquifer. Grain size is not the only reason for the permeable or impermeable nature of waste material - the grain ordering and the compaction of levels at depth also have a role

A case of functional vitamin B12 deficiency after recreational nitrous oxide use

Highlights Vitamin B12 and holotranscobalamin may be normal in chronic nitrous oxide users Nitrous oxide induces a defect in vitamin B12-mediated functions Homocysteine and methylmalonic acid help identify N2O-users with B12 deficiency The recreational use of nitrous oxide as laughing gas becomes a real public health issue among adolescents and young adults. Chronic use is deleterious and can lead to severe neurological disorders. Nitrous oxide inactivates vitamin B12, and the functional defect of vitamin B12 plays a major role in the pathogenesis of nitrous oxide-related neurological disorders. Here we report the case of a 22-year-old woman who came to the hospital after an unexplained loss of consciousness. She exhibited typical features of vitamin B12 or folate deficiency such as macrocytic anemia and hypersegmented neutrophils. However, serum concentrations of folate and vitamin B12 were normal. In contrast, circulating concentrations of total homocysteine and methylmalonic acid were significantly increased. These results clearly indicated a defect in vitamin B12 functions. The reason for this defect was clarified when she revealed that she had been consuming nitrous oxide recreationally for over a year. The present case points out the challenges in diagnosing vitamin B12 deficiency in the context of nitrous oxide abuse due to normal concentrations of total serum vitamin B12 in a significant proportion of cases. The medical community should be aware of how difficult it can be to interpret B12 status in this specific population

Les valeurs d'ouverture à l'altérité dans les manuels de français libanais : aspects d'un traitement paradoxal

Au Liban, la décennie 1990 a été marquée par la sortie de la guerre et par la mise en œuvre d'une importante réforme éducative mettant la question des valeurs du vivre ensemble et du rapport à l'altérité au centre des préoccupations. Nous abordons ces valeurs et cette éducation à l'altérité telles qu'elles s'énoncent dans les textes officiels d'une part, et telles qu'elles apparaissent dans les manuels de français d'autre part, à travers les représentations du Liban et des pays francophones. La particularité du contexte libanais, entre éducation post-conflit et tensions intercommunautaires encore vives, rend complexes la construction de l'unité nationale et les modalités d'ouverture à l'Autre : la description scolaire revêt ainsi des allures paradoxales, lorsqu'elle entreprend d'éduquer à l'altérité sans représenter la diversité sociale libanaise, ni traiter de la ou des cultures cibles comme de cultures étrangères. Nous décrivons des procédés d'occultation et de contournement divers tout comme nous tentons de cerner le rôle que joue l'enseignement du français dans l'éducation aux valeurs.In Lebanon, after the 1975-1990 war, an important educational reform emphasized the question of coexistence, respect of otherness and values. In this paper I examine these values and education to otherness as they appear in the official instructions of the ministry of education, and how teaching French textbooks convey them, through representations of Lebanon and of French-speaking countries. Lebanon's particular background, between post-conflict education and strained inter-community relationships, complicates the shaping of national unity and openness to others ; the textbooks' discourses become paradoxical when they try to teach a way of living together without showing Lebanese social diversity, nor presenting the target cultures as foreign cultures. I try to highlight how they avoid such taboo subjects, and which role French teaching plays in passing down educational values

Emerging perspectives on once-weekly insulins in type 1 and type 2 diabetes: a mini-review

The development of once-weekly basal insulin analogues, such as insulin icodec and efsitora alfa, represents a promising strategy to reduce injection burden and improve adherence in diabetes management. This mini-review summarizes the recent findings from clinical trials evaluating once-weekly insulin therapies in both type 1 and type 2 diabetes. In type 1 diabetes, available data remain limited; however, the ONWARDS 6 and QWINT-5 trials demonstrated that once-weekly icodec and efsitora, respectively, achieved comparable reductions in HbA1c to once-daily insulin degludec, when used in combination with prandial insulin. In type 2 diabetes, accumulating evidences from randomized clinical trials supports the efficacy of once-weekly icodec and efsitora, showing non-inferiority—and in some cases, superiority—compared to once-daily basal insulin, both in insulin-naïve individuals and in those previously treated with insulin. Safety profiles of once-weekly insulins in type 2 diabetes are reassuring, with similar rates of clinically significant and severe hypoglycemia compared to once-daily regimens. In contrast, trials in type 1 diabetes reported higher hypoglycemia rates with once-weekly insulins. Recent findings from the COMBINE program demonstrated that the fixed-ratio combination of icodec and semaglutide (IcoSema) produced superior HbA1c reductions compared to either agent alone, though not superior to a basal-bolus regimen with glargine and aspart insulin. However, several important questions remain to be addressed regarding once-weekly insulins, including their long-term efficacy on cardiovascular outcomes and overall long-term safety

Hierarchical Factor Classification of Dendrochronological Time-Series

In this paper, Hierarchical Factor Classification (HFC), an exploratory method of classification of characters is introduced, in comparison with Principal Component Analysis (PCA) in order to show its advantages, in particular when dealing with time series. Exploratory data analysis may play a very relevant role in the understanding of the structure of a data set prior the use of statistical methods – as hypothesis testing and inference, and models. The study of tree-rings time series through exploratory methods may also take advantages, by allowing some interpretation to be further checked via a small number of statistical tests. In particular, while providing overall results close to those of PCA, HFC complements it, by providing a classification of the time-series and estimating a representative chronology for each group, common to the clustered ones. As case study, a data set is taken from literature, composed by five synchronous 79 years-long chronologies of Pinus pinea L., from five different populations scattered along the Tyrrhenian coast in peninsular Italy. HFC suggests how conveniently aggregate the chronologies, by showing similarities and differences between them, otherwise unnoticed, suggesting to limit the aggregation to three chronologies only

Kriging Surrogate Models for Predicting the Complex Eigenvalues of Mechanical Systems Subjected to Friction-Induced Vibration

This study focuses on the kriging based metamodeling for the prediction of parameter-dependent mode coupling instabilities. The high cost of the currently used parameter-dependent Complex Eigenvalue Analysis (CEA) has induced a growing need for alternative methods. Hence, this study investigates capabilities of kriging metamodels to be a suitable alternative. For this aim, kriging metamodels are proposed to predict the stability behavior of a four-degree-of-freedom mechanical system submitted to friction-induced vibrations. This system is considered under two configurations defining two stability behaviors with coalescence patterns of different complexities. Efficiency of kriging is then assessed on both configurations. In this framework, the proposed kriging surrogate approach includes a mode tracking method based on the Modal Assurance Criterion (MAC) in order to follow the physical modes of the mechanical system. Based on the numerical simulations, it is demonstrated by a comparison with the reference parameter-dependent CEA that the proposed kriging surrogate model can provide efficient and reliable predictions of mode coupling instabilities with different complex patterns

Extreme hyperferritinemia in the setting of acute myeloid leukaemia: a case report of hemophagocytic lymphohistiocytosis.

Introduction: Major hyperferritinemia is a rare feature in clinical laboratories associated with a wide variety of disorders, including hemophagocytic lymphohistiocytosis (HLH). The diagnosis of HLH is based on clinical and biological criteria, such as those proposed by the Histiocyte Society. However, several of these criteria are not relevant in the specific setting of hematologic malignancies. Materials and methods: A 69-year-old male was treated for an acute myeloid leukaemia. On day 15 after the start of chemotherapy, he developed severe sepsis with high fever, low blood pressure and hepatosplenomegaly. Results: Blood tests were marked by extreme hyperferritinemia (191,000 µg/L, reference range: 26-388 µg/L) with increased C-reactive protein (87.0 mg/L) and procalcitonin (1.94 µg/L) and aspartate aminotransferase (499 U/L 37 °C) in the setting of chemotherapy-induced aplasia. This unusual extreme ferritinemia led to suspect HLH triggered by an invasive infection. Under intensive treatment, the clinical status improved and ferritin levels significantly decreased. Conclusions: The diagnosis of HLH is usually based on clinical and biological criteria, mainly fever, splenomegaly, cytopenias, hypertriglyceridemia, hypofibrinogenemia, hemophagocytosis and hyperferritinemia. In this patient, the diagnosis of HLH was challenging because several criteria, such as hypertriglyceridemia, hemophagocytosis and hypofibrinogenemia, were absent. In addition, some criteria of HLH are not relevant in the setting of hematologic malignancy, in which fever, splenomegaly, cytopenias and elevated lactate dehydrogenase are commonly observed independently of HLH. This unusual case of extremely high ferritinemia emphasizes the important weight of the ferritin level for the diagnosis of HLH in adult patients in the setting of hematologic malignancies

Crack-damage quantification based on stochastic optimization of finite element models with data-driven features

International audienceThe vibration-based Structural Health Monitoring plays a central role in ensuring the safe operation of infrastructures by monitoring their structural integrity based on data collected by sensors. While damage detection has reached maturity, the localization and the quantification of small-scale damage remain an open challenge. To address it, both the localization and the quantification of damage are often posed as an updating problem of a Finite Element Model (FEM) of the operating structure, minimizing the misfit between some features computed from response measurements of a faulty structure and its FEM in a reference, healthy condition. This paper investigates the choice of the features for the design of the objective function to quantify structural cracks. For this purpose, a FEM of a beam with a transverse crack is developed and parametrized by the second moment of area of the elements to locate and quantify the crack-related damage. Subsequently, the impact on the choice of the objective function is discussed based on a small-samples Monte Carlo study