Efficient Implicit Parallel Patterns for Geographic Information System

International audienceWith the data growth, the need to parallelize treatments become crucial in numerous domains. But for non-specialists it is still difficult to tackle parallelism technicalities as data distribution, communications or load balancing. For the geoscience domain we propose a solution based on implicit parallel patterns. These patterns are abstract models for a class of algorithms which can be customized and automatically transformed in a parallel execution. In this paper, we describe a pattern for stencil computation and a novel pattern dealing with computation following a pre-defined order. They are particularly used in geosciences and we illustrate them with the flow direction and the flow accumulation computations

An Hierarchical Labeling Technique for Interactive Computation of Watersheds

International audience—The watershed computation is a prevalent task in the geographical information systems. It is used, among other purposes, to forecast the pollutant concentration and its impact on the water quality. The algorithm to compute the watershed can be hard to parallelize and with the increasingly data growth, the need for parallel computation increases. In this paper we propose a new method to parallelize the watershed computation. Our algorithm is decomposed into two tasks, the parallel watershed segmentation into a hierarchy that allows in a second task to retrieve randomly large watersheds at run-time in interactive time

Slip Distribution of the 1952 Kamchatka Great Earthquake Based on Near-Field Tsunami Deposits and Historical Records

We explore the magnitude and slip distribution of the 1952 Kamchatka earthquake (MW 8.8–9.0) using constraints from the 1952 Kamchatka tsunami. Our new field data provide more comprehensive coverage of the near-field tsunami than had been available to date. We examine the effects of internal slip distribution within complex earthquake ruptures on near-field tsunami runup and evaluate some of the limitations of this approach. Our approach compares tsunami-deposit distribution with simulated runup from tsunamis generated by different configurations of seafloor deformation from hypothetical earthquakes resembling that of the 1952 Kamchatka earthquake. We identify areas of high slip because different distributions of seafloor deformation result in variations in tsunami runup in the near field. Mapped deposits and local observations of the 1952 Kamchatka tsunami indicate that near-field runup in central Kamchatka was consistently less than 10 m (averaging 6 m), while south Kamchatka to the northern Kuril Islands had more variability and higher average runup (8 m runup in South Kamchatka and 10 m runup in the northern Kuril Islands). Our simulations show that in order to produce the distribution of runup indicated by tsunami deposits and historical observations, the 1952 earthquake had regions of high slip off the coast of southern Kamchatka, and the location of high slip is shallower in the subduction zone than previously interpreted

Neutral Assessment of the National Research Council Canada Evaluation Function

Federal government departments and agencies are required to conduct a neutral assessment of their evaluation function once every five years under the Treasury Board Secretariat’s Policy on Evaluation (2009). This article describes the National Research Council’s experience conducting the first neutral assessment of its evaluation function. Based on learning from this first assessment, best practices that NRC intends on replicating, as well as lessons learned for future assessments, are discussed. This article may be of interest to both federal and non-federal organizations seeking to conduct a neutral assessment in an effort to improve their evaluation services and products.Les ministères et les agences du gouvernement fédéral doivent effectuer un examen neutre de leur fonction d’évaluation une foisà tous les cinq ans selon la politique du Secrétariat du Conseildu Trésor sur l’évaluation (2009). Cet article décrit l’expérience du Conseil national de recherches du Canada dans le cadre de la réalisation du premier examen neutre de sa fonction d’évaluation. À partir des apprentissages découlant du premier examen, les bonnes pratiques ainsi que les leçons apprises que le CNRC entend répliquer dans des exercices futures sont discutées. Cet article pourrait s’avérer d’intérêt pour les organisations fédérales et non-fédérales cherchant à mener un examen neutre dans le but d’améliorer leurs services et produits d’évaluation

The use of antidepressants in Belgian nursing homes : focus on indications and dosages in the PHEBE study

Background : Since antidepressants are prescribed for multiple indications, the use of an antidepressant cannot be equated with a diagnosis of depression. Objective : The objective of this study was to examine the quality of antidepressant prescribing in Belgian nursing homes, with a critical evaluation of indications and dosages, to see whether depression was appropriately treated in terms of drug choice, the indications for which antidepressants were being prescribed and whether there was underdosing. Methods : This analysis was based on data obtained in the Prescribing in Homes for the Elderly in Belgium (PHEBE) study, a cross-sectional, descriptive study of a representative, stratified, random sample of 1,730 residents from 76 Belgian nursing homes. The PHEBE study investigated overall drug utilization in Belgian nursing homes in 2006. Clinical and medication data for the present study were obtained from this study. A 28-item checklist of clinical conditions was designed ad hoc for the PHEBE study and sent to the residents' general practitioners (GPs) to collect clinical information. We copied the residents' medication charts, classified the drugs using the Anatomical Therapeutic Chemical (ATC) classification system codes and transferred the drug names and dosages into a database. Information on indications was retrospectively obtained from the GPs, so that we could link the indication to each medication. Minimum effective doses (MEDs) of antidepressants to treat major depression were obtained from the literature to assess underdosing. Results : The overall use of antidepressants in nursing homes was 39.5 % (95 % CI 37.2, 41.8). The physicians classified 34.2 % (95 % CI 32.0, 36.4) of the residents as having depression, and 80.9 To of these patients were treated with an antidepressant. Indications among the single antidepressant users (n = 551) were depression (66.2 %), insomnia (13.4 %), anxiety (6.2 %) and neuropathic pain (1.6 %). In the indication of depression, 74.8 % used a selective serotonin reuptake inhibitor (SSRI), predominantly citalopram, sertraline and escitalopram. Venlafaxine was used by 10.7 % of the residents. Dosages for these antidepressants were equal to or higher than the MED. But when trazodone, amitriptyline or mirtazapine were used to treat depression, respectively, 92.3, 55.5 and 44.5 % of prescribed dosages were below the MED. In the indication of insomnia, most of the time, trazodone (90.5 %) or mirtazapine (5.4 %) were used, and in lower dosages than those required for depression treatment (<MED). Tricyclic antidepressants were predominantly used for the treatment of neuropathic pain and were also used at lower dosages. Of all the residents receiving a medication for anxiety, only 13.9 % received an antidepressant (mostly an SSRI), and the remaining received a benzodiazepine. Conclusions : The number one indication for the use of an antidepressant was depression. Within this indication, mostly the recommended SSRIs were used, in dosages equal to or higher than the MED. Furthermore, we noticed that there was substantial use of sedative antidepressants for insomnia and that the physicians preferred to prescribe benzodiazepines over the recommended SSRIs to treat anxiety chronically