2D multi-objective placement algorithm for free-form components

This article presents a generic method to solve 2D multi-objective placement problem for free-form components. The proposed method is a relaxed placement technique combined with an hybrid algorithm based on a genetic algorithm and a separation algorithm. The genetic algorithm is used as a global optimizer and is in charge of efficiently exploring the search space. The separation algorithm is used to legalize solutions proposed by the global optimizer, so that placement constraints are satisfied. A test case illustrates the application of the proposed method. Extensions for solving the 3D problem are given at the end of the article.Comment: ASME 2009 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference, San Diego : United States (2009

La dégradation de la matière organique dissoute comme indicateur de la réactivité écosystémique du fleuve Saint-Laurent

La matière organique dissoute (MOD) joue un rôle clé dans le fonctionnement des rivières à titre de vecteur de carbone organique et d’énergie, tout en contribuant au transport de nutriments, de métaux et de divers contaminants. Elle est principalement dégradée à travers la minéralisation photochimique et la respiration bactérienne. La vitesse à laquelle se produit cette dégradation est influencée à la fois par la composition chimique et moléculaire de la MOD et par les conditions environnementales dans lesquelles elle est transformée. Toutefois, les études évaluant simultanément ces effets intrinsèques et extrinsèques sont rares en milieu fluvial et la plupart se concentrent sur un seul des processus de dégradation. De plus, les résultats de ces expériences sont rarement transposés à une colonne d’eau entière, ce qui limite l’évaluation de la réactivité écosystémique en rivière. Durant l’été 2019, nous avons échantillonné 40 sites le long d’un transect de 207 kilomètres sur le fleuve Saint-Laurent, une grande rivière tempérée dans laquelle s’écoulent côte-à-côte deux masses d’eau contrastées en termes de propriétés chimiques et physiques. En laboratoire, nous avons évalué la bio- et la photo-réactivité de la MOD au moyen d’incubations et d'expositions sous un simulateur solaire pour ensuite transposer ces données à l’écosystème en estimant pour tous les sites échantillonnés des taux surfaciques de dégradation in situ à partir de profils lumineux et bathymétriques. Nos résultats indiquent que la dégradation in situ de la MOD est essentiellement déterminée par la dégradation biologique. Cette dernière est généralement un à deux ordres de grandeur plus importante que la dégradation photochimique. Les taux surfaciques totaux de dégradation (calculés comme la somme des taux de dégradation photochimique et biologique) vont de 36,7 à 892,1 mg C m-2 j-1. Les taux surfaciques de dégradation photochimique sont principalement influencés par la photoréactivité de la MOD. En revanche, nous avons identifié un pool relativement constant de MOD bioréactive qui semble indépendant de la concentration initiale, de la composition ou des conditions environnementales. Des taux disproportionnellement élevés de biodégradation (2,5 à 4 fois la moyenne) ont été observés pour quelques sites peu profonds et situés près d’effluents urbains ou d’îles. Ces taux sont probablement stimulés par une combinaison de concentrations élevées en nutriments et une proportion plus importante de composantes protéiniques dans la MOD. Nos travaux fournissent l’une des rares démonstration expérimentale de la dominance de la dégradation biologique dans les grandes rivières, mais révèlent que la dégradation photochimique peut être d’importance comparable dans certaines zones de faible profondeur plus fortement connectées au milieu terrestre. En somme, ces observations suggèrent l’existence de points de contrôle écosystémiques pour la réactivité de la MOD dans les grandes rivières et laissent entrevoir de nouveaux questionnements quant à leur rôle dans l’export et le transport de matière terrestre.Dissolved organic matter (DOM) is central to rivers functioning as it is a complex mixture composed of vast amounts of organic carbon and energy, also acting as a vector for nutrients, metals and various contaminants. Both the chemical and molecular composition of the DOM and the environmental conditions in which it is processed can influence its rate of removal from the water column, mainly through photochemical mineralization and bacterial respiration. Studies evaluating these intrinsic and extrinsic aspects simultaneously, particularly on both the biological and photochemical degradation are rare, particularly in large fluvial systems. During the summer of 2019, we sampled a 207 km transect of the St. Lawrence (SLR), a large temperate river in which flows two strikingly distinct water masses in terms of origin as well as chemical and physical properties. We then assessed DOM bio- and photo-reactivity at 40 sites along the river through a series of standardized incubations and exposure to simulated sunlight, and then used water irradiance and morphometric profiles to estimate in situ areal rates of processing across the river. We found that the in situ reactivity was mostly driven by biological degradation, which was typically one to two order of magnitude higher than photochemical degradation. Total daily processing (calculated as the sum of photochemical and biological degradation) across the whole water column ranged from 36.7 to 892.1 mg C m-2 d-1. In situ photochemical degradation was largely driven by DOM photoreactivity. In contrast, we found a relatively constant baseline pool of biolabile DOM that appeared to be independent from changes in concentration and environmental conditions. Disproportionately high biodegradation rates (2.5-4x the average) were found in a few shallower sites, near effluents or islands, potentially driven by a combination of local increases in nutrient concentration and compositional changes in the proportion of protein-like DOM. We provide rare experimental evidence for the often-assumed dominance of biodegradation over photodegradation in large rivers, but also emphasize that photodegradation can locally be just as important in terrestrially connected areas of low depth. In turn, these observations hint at the presence of ecosystem control points in large and heterogenous rivers with contrasting sources and composition of DOM, opening new research perspectives into the role of large rivers in the export and retention of terrestrial matter

Optimisation de placement dans les problèmes de conception

Dans les problèmes de conception, l'optimisation du placement des composants peut jouer un rôle prédéterminant sur les performances du système à concevoir. Le papier présenté propose une méthode de placement des composants, basée sur un algorithme évolutionnaire couplé à une méthode de séparation des composants. La méthode permet de traiter les problèmes multi-objectifs contraints, et permet au concepteur d'interagir avec les solutions proposées

International consensus guidelines on surveillance for pancreatic cancer in chronic pancreatitis. Recommendations from the working group for the international consensus guidelines for chronic pancreatitis in collaboration with the International Association of Pancreatology, the American Pancreatic Association, the Japan Pancreas Society, and European Pancreatic Club

Background: Patients with chronic pancreatitis (CP) have an increased risk of pancreatic cancer. We present the international consensus guidelines for surveillance of pancreatic cancer in CP. Methods: The international group evaluated 10 statements generated from evidence on 5 questions relating to pancreatic cancer in CP. The GRADE approach was used to evaluate the level of evidence available per statement. The working group voted on each statement for strength of agreement, using a nine-point Likert scale in order to calculate Cronbach's alpha reliability coefficient. Results: In the following domains there was strong consensus: (1) the risk of pancreatic cancer in affected individuals with hereditary pancreatitis due to inherited PRSS1 mutations is high enough to justify surveillance; (2) the risk of pancreatic cancer in patients with CP associated with SPINK1 p. N34S is not high enough to justify surveillance; (3) surveillance should be undertaken in pancreatic specialist centers; (4) surveillance should only be introduced after the age of 40 years and stopped when the patient would no longer be suitable for surgical intervention. All patients with CP should be advised to lead a healthy lifestyle aimed at avoiding risk factors for progression of CP and pancreatic cancer. There was only moderate or weak agreement on the best methods of screening and surveillance in other types of environmental, familial and genetic forms of CP. Conclusions: Patients with inherited PRSS1 mutations should undergo surveillance for pancreatic cancer, but the best methods for cancer detection need further investigation

A Microscope Automated Fluidic System to Study Bacterial Processes in Real Time

Most time lapse microscopy experiments studying bacterial processes ie growth, progression through the cell cycle and motility have been performed on thin nutrient agar pads. An important limitation of this approach is that dynamic perturbations of the experimental conditions cannot be easily performed. In eukaryotic cell biology, fluidic approaches have been largely used to study the impact of rapid environmental perturbations on live cells and in real time. However, all these approaches are not easily applicable to bacterial cells because the substrata are in all cases specific and also because microfluidics nanotechnology requires a complex lithography for the study of micrometer sized bacterial cells. In fact, in many cases agar is the experimental solid substratum on which bacteria can move or even grow. For these reasons, we designed a novel hybrid micro fluidic device that combines a thin agar pad and a custom flow chamber. By studying several examples, we show that this system allows real time analysis of a broad array of biological processes such as growth, development and motility. Thus, the flow chamber system will be an essential tool to study any process that take place on an agar surface at the single cell level

Melanocortin-1 receptor, skin cancer and phenotypic characteristics (M-SKIP) project

Background: For complex diseases like cancer, pooled-analysis of individual data represents a powerful tool to investigate the joint contribution of genetic, phenotypic and environmental factors to the development of a disease. Pooled-analysis of epidemiological studies has many advantages over meta-analysis, and preliminary results may be obtained faster and with lower costs than with prospective consortia. Design and methods. Based on our experience with the study design of the Melanocortin-1 receptor (MC1R) gene, SKin cancer and Phenotypic characteristics (M-SKIP) project, we describe the most important steps in planning and conducting a pooled-analysis of genetic epidemiological studies. We then present the statistical analysis plan that we are going to apply, giving particular attention to methods of analysis recently proposed to account for between-study heterogeneity and to explore the joint contribution of genetic, phenotypic and environmental factors in the development of a disease. Within the M-SKIP project, data on 10,959 skin cancer cases and 14,785 controls from 31 international investigators were checked for quality and recoded for standardization. We first proposed to fit the aggregated data with random-effects logistic regression models. However, for the M-SKIP project, a two-stage analysis will be preferred to overcome the problem regarding the availability of different study covariates. The joint contribution of MC1R variants and phenotypic characteristics to skin cancer dev

Melanocortin-1 Receptor, Skin Cancer and Phenotypic Characteristics (M-SKIP) Project: Study Design and Methods for Pooling Results of Genetic Epidemiological Studies

Background: For complex diseases like cancer, pooled-analysis of individual data represents a powerful tool to investigate the joint contribution of genetic, phenotypic and environmental factors to the development of a disease. Pooled-analysis of epidemiological studies has many advantages over meta-analysis, and preliminary results may be obtained faster and with lower costs than with prospective consortia. Design and methods: Based on our experience with the study design of the Melanocortin-1 receptor (MC1R) gene, SKin cancer and Phenotypic characteristics (M-SKIP) project, we describe the most important steps in planning and conducting a pooled-analysis of genetic epidemiological studies. We then present the statistical analysis plan that we are going to apply, giving particular attention to methods of analysis recently proposed to account for between-study heterogeneity and to explore the joint contribution of genetic, phenotypic and environmental factors in the development of a disease. Within the M-SKIP project, data on 10,959 skin cancer cases and 14,785 controls from 31 international investigators were checked for quality and recoded for standardization. We first proposed to fit the aggregated data with random-effects logistic regression models. However, for the M-SKIP project, a two-stage analysis will be preferred to overcome the problem regarding the availability of different study covariates. The joint contribution of MC1R variants and phenotypic characteristics to skin cancer development will be studied via logic regression modeling. Discussion: Methodological guidelines to correctly design and conduct pooled-analyses are needed to facilitate application of such methods, thus providing a better summary of the actual findings on specific fields

Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research