Évaluation d'un modèle a priori basé sur un seuillage de la TCD en super-résolution et comparaison avec d'autres modèles a priori

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Aide au processus décisionnel pour la gestion par bassin versant au Québec : étude de cas et principaux enjeux

Les conditions particulières prévalant lors de l’application d’une approche de gestion par bassin versant au Québec (Canada) font appel à de nouvelles méthodologies intégrées pour faciliter l’analyse et le partage des informations, les conditions de négociation entre les parties prenantes et la mise en oeuvre des choix d’aménagement ou de gestion retenus. Cet article met en perspective la modélisation des processus décisionnels territoriaux à l’échelle des bassins versants (BV). Il dégage certains enjeux méthodologiques se rattachant à cette problématique de gestion dans sa dimension informationnelle, dans le contexte du Québec. Il montre l’interconnexion des préoccupations décisionnelles aux conditions d’utilisation d’une plate-forme géomatique à même de modéliser de tels processus territoriaux dans le cadre d’un système intégré d’aide à la décision (SIAD). Finalement, il recommande l’évaluation de l’utilisation d’un tel système (SIAD-BV) pour faciliter l’émergence des conditions d’application de l’approche de la gestion intégrée par bassin versant au Québec, à partir des discussions réalisées avec des intervenants des bassins Chaudière et Outaouais.The unique conditions that prevail when a political approach to watershed management in Quebec (Canada) is taken, requires a need for integrated methodologies to promote the following: information sharing and analysis, negotiation of conditions among stakeholders and introduction of selected management alternatives. This article brings the modelling of regional decision-making processes that apply to watershed management (WM) into perspective. It discusses the methodological challenges relating to information that are inherent to this management issue, particularly in a Québec (Canada) context. It shows links between decisional concerns and geomatic skills for modelling these regional processes, as an integrated decision support system (IDSS). Lastly, it recommends assessing the use of this type of system to promote the emergence of conditions where such an approach to watershed management in Québec could be implemented, based on interviews conducted with regional professionals in the Chaudière and Outaouais basins

Modeling RNA tertiary structure motifs by graph-grammars

A new approach, graph-grammars, to encode RNA tertiary structure patterns is introduced and exemplified with the classical sarcin–ricin motif. The sarcin–ricin motif is found in the stem of the crucial ribosomal loop E (also referred to as the sarcin–ricin loop), which is sensitive to the α-sarcin and ricin toxins. Here, we generate a graph-grammar for the sarcin-ricin motif and apply it to derive putative sequences that would fold in this motif. The biological relevance of the derived sequences is confirmed by a comparison with those found in known sarcin–ricin sites in an alignment of over 800 bacterial 23S ribosomal RNAs. The comparison raised alternative alignments in few sarcin–ricin sites, which were assessed using tertiary structure predictions and 3D modeling. The sarcin–ricin motif graph-grammar was built with indivisible nucleotide interaction cycles that were recently observed in structured RNAs. A comparison of the sequences and 3D structures of each cycle that constitute the sarcin–ricin motif gave us additional insights about RNA sequence–structure relationships. In particular, this analysis revealed the sequence space of an RNA motif depends on a structural context that goes beyond the single base pairing and base-stacking interactions

Tracking larvae with molecular markers reveals high relatedness and early seasonal recruitment success in a partially spawning marine bivalve

The partial synchronized spawning strategy\ud adopted by some marine invertebrate broadcast-spawners\ud can lead to the production of many distinct pools of larvae\ud within a single reproductive cycle. Following the fate of\ud these larval groups from birth to settlement with molecular\ud markers might shed light on mechanisms regulating their\ud population recruitment. Larvae and recruits of Mya arenaria,\ud a partially spawning marine bivalve, were monitored\ud and collected over 13 consecutive weeks during an entire\ud reproductive cycle. Each sampled individual (n = 218)\ud was sorted according to size (early veligers, late veligers,\ud post-larval recruits) and genotyped at seven microsatellite\ud loci for comparisons among samples and with adult reference\ud samples (n = 270). While traditional differentiation\ud statistics (e.g., pairwise ϴST, allelic richness) suggested\ud the absence of sweepstakes reproductive success, the level of relatedness found within and among larvae and recruit\ud samples suggested otherwise. Four samples out of ten were\ud observed to have higher within-sample relatedness values\ud than randomly expected, including the very first group\ud of early veligers produced in the season (E1) and the last\ud group of post-larvae who survived recruitment (P10). E1\ud individuals were also found to be more related than randomly\ud expected to individuals of more than 80 % of all\ud other samples including the last surviving recruits (P8 and\ud P10). These results suggest that the first larvae produced\ud in the season were the most successful to survive recruitment.\ud Results also show direct evidence for larval retention\ud and demonstrate for the first time larval and post-larval kin\ud aggregation in a marine bivalve

Are Paleomagnetic Records From U‐Channels Appropriate for Studies of Reversals and Excursions?

Sampling of sediment cores using plastic U‐channels has made possible the acquisition of detailed records of paleomagnetic secular variation, geomagnetic polarity, environmental magnetic studies, and relative paleointensity over the past several million years. U‐channel measurements provide the great advantage of rapid measurements of long sediment cores, but the signal resolution is attenuated by the response function of the magnetometer sensors, which therefore restrains the recovery of rapid and large‐amplitude field changes. Here we focus on the suitability of the dynamics of reversals and excursions derived from U‐channel measurements. We compare successive individual paleomagnetic directions of 1.5 cm × 1.5 cm × 1.5 cm cubic discrete samples with those of a 1.5‐m equivalent U‐channel sample train obtained by placing the samples adjacent to each other. We use varying excursion and transition lengths and generate transitional directions that resemble those of the most detailed paleomagnetic records. Excursions with opposite polarity directions recorded over less than 7.5 cm are barely detected in U‐channel measurements. Regarding reversals, U‐channel measurements smooth the signal of low‐resolution records and generate artificial transitional directions. Despite producing misleading similarities with the overall structure of transition records, longer transitional intervals fail also to reproduce the complexity of field changes. Finally, we test the convolution of magnetization by different response functions. The simulation reveals that even small response function changes can generate significant differences in results. -- Keywords : geomagnetic reversals ; geomagnetic excursions ; paleomagnetic measurements

Recent sedimentation in three adjacent fjord-lakes on the Québec North Shore (eastern Canada): facies analysis, laminae preservation, and potential for varve formation

Cet article analyse de courtes carottes gravitaires échantillonnées le long de transects dans trois lacs de fjord profonds adjacents (les lacs Pentecôte, Walker et Pasteur) sur la Côte-Nord du Québec (est du Canada), afin d’évaluer la répartition de sédiments laminés et le potentiel de formation de varves. L’analyse des faciès basée sur la description lithologique, des photos numériques, des images par tomodensitométrie et des données bathymétriques, a permis l’identification de quatre principaux faciès sédimentaires : des sédiments laminés, des sédiments partiellement laminés, des sédiments bioturbés et des sédiments massifs. Des preuves directes sur la stratification thermique du Lac Walker ont été acquises de 2014 à 2016. Les taux de sédimentation moyens et les flux de sédimentation postglaciaires dans les bassins distaux des trois lacs étudiés sont ≤0,12 cm a−1 et de 0,03 à 0,16 g cm−2 a−1, respectivement, à la lumière de la datation aux 210Pb, 137Cs et radiocarbone par SMA. Sur la base de l’analyse d’images de lames minces et d’un modèle de chronologie du 210Pb (CIC), le Lac Pentecôte contient des sédiments principalement massifs à partiellement laminés, alors que le Lac Pasteur contient des sédiments partiellement laminés et des sédiments laminés non annuels ressemblants à des varves. Le Lac Walker contient toutefois des sédiments laminés qui sont vraisemblablement des varves. Le plus grand potentiel de préservation de laminations observé pour le lac Walker par rapport aux lacs Pentecôte et Pasteur est associé à des caractéristiques morphologiques plus favorables, dont sa profondeur relative, sa profondeur moyenne, sa profondeur maximum et son exposition topographique plus importantes. -- Keywords : Limnogeology ; sedimentary structures ; laminations ; varves ; CT-scan ; Québec North Shore

Experts Consensus Recommendations for the Management of Calcium Channel Blocker Poisoning in Adults

Objective: To provide a management approach for adults with calcium channel blocker poisoning. Data Sources, Study Selection, and Data Extraction: Following the Appraisal of Guidelines for Research & Evaluation II instrument, initial voting statements were constructed based on summaries outlining the evidence, risks, and benefits. Data Synthesis: We recommend 1) for asymptomatic patients, observation and consideration of decontamination following a potentially toxic calcium channel blocker ingestion (1D); 2) as first-line therapies (prioritized based on desired effect), IV calcium (1D), high-dose insulin therapy (1D-2D), and norepinephrine and/or epinephrine (1D). We also suggest dobutamine or epinephrine in the presence of cardiogenic shock (2D) and atropine in the presence of symptomatic bradycardia or conduction disturbance (2D); 3) in patients refractory to the first-line treatments, we suggest incremental doses of high-dose insulin therapy if myocardial dysfunction is present (2D), IV lipid-emulsion therapy (2D), and using a pacemaker in the presence of unstable bradycardia or high-grade arteriovenous block without significant alteration in cardiac inotropism (2D); 4) in patients with refractory shock or who are periarrest, we recommend incremental doses of high-dose insulin (1D) and IV lipid-emulsion therapy (1D) if not already tried. We suggest venoarterial extracorporeal membrane oxygenation, if available, when refractory shock has a significant cardiogenic component (2D), and using pacemaker in the presence of unstable bradycardia or high-grade arteriovenous block in the absence of myocardial dysfunction (2D) if not already tried; 5) in patients with cardiac arrest, we recommend IV calcium in addition to the standard advanced cardiac life-support (1D), lipid-emulsion therapy (1D), and we suggest venoarterial extracorporeal membrane oxygenation if available (2D). Conclusion: We offer recommendations for the stepwise management of calcium channel blocker toxicity. For all interventions, the level of evidence was very low

Dredging and canal gate technologies in Portus, the ancient harbour of Rome, reconstructed from event stratigraphy and multi-proxy sediment analysis

Ancient harbours are rich archives of human-environment interaction. However, dating harbour deposits and correlating their stratigraphy is a major challenge because of typically high sedimentation rates over short periods and possible curative dredging events. Portus, the maritime harbour of Rome at the height of the Roman Empire, was a port complex composed of basins and canals connecting the commercial harbour to Rome via the Tiber River. Sediment core CPS1 in the narrowest of these canals, Canale Traverso, is located centrally in what was the capital city's commercial hub and contains a continuous harbour depositional record with average sedimentation rates greater than 1 cm per year. Here we use piston coring, high-resolution core scanning and a multi-proxy sediment analysis including for the first time paleo- and rock-magnetism, and bulk and clay mineralogy in order to overcome the problems of dating harbour deposits and correlating their stratigraphy. The method allowed precise identification of major reworked events, including a dredged deposit and a hyperpycnal deposit, which improve the chronostratigraphy and water depth reconstruction, and sheds light on harbour technologies at the height of the Roman Empire. A debris layer with abundant ceramic fragments and rocks marks the decommissioning of Canale Traverso and provides a new chronostratigraphic marker at Portus. Multi-proxy riverine input signatures point to the possible use of canal gate technology for water flow management

Sleep and energy intake in early childhood

Background And Objectives: Shorter sleep is associated with higher weight in children, but little is known about the mechanisms. The aim of this study was to test the hypothesis that shorter sleep was associated with higher energy intake in early childhood. Methods: Participants were 1303 families from the Gemini twin birth cohort. Sleep duration was measured using the Brief Infant Sleep Questionnaire when the children were 16 months old. Total energy intake (kcal per day) and grams per day of fat, carbohydrate and protein were derived from 3-day diet diaries completed by parents when children were 21 months old. Results: Shorter nighttime sleep was associated with higher total energy intake (P for linear trend=0.005). Children sleeping <10 h consumed around 50 kcal per day more than those sleeping 11–<12 h a night (the optimal sleep duration for children of this age). Differences in energy intake were maintained after adjustment for confounders. As a percentage of total energy intake, there were no significant differences in macronutrient intake by sleep duration. The association between sleep and weight was not significant at this age (P=0.13). Conclusions: This study provides the first evidence that shorter nighttime sleep duration has a linear association with higher energy intake early in life. That the effect is observed before emergence of associations between sleep and weight indicates that differences in energy intake may be a mechanism through which sleep influences weight gain

Fifteen years of research on oral–facial–digital syndromes: from 1 to 16 causal genes

Oral–facial–digital syndromes (OFDS) gather rare genetic disorders characterised by facial, oral and digital abnormalities associated with a wide range of additional features (polycystic kidney disease, cerebral malformations and several others) to delineate a growing list of OFDS subtypes. The most frequent, OFD type I, is caused by a heterozygous mutation in the OFD1 gene encoding a centrosomal protein. The wide clinical heterogeneity of OFDS suggests the involvement of other ciliary genes. For 15 years, we have aimed to identify the molecular bases of OFDS. This effort has been greatly helped by the recent development of whole-exome sequencing (WES). Here, we present all our published and unpublished results for WES in 24 cases with OFDS. We identified causal variants in five new genes (C2CD3, TMEM107, INTU, KIAA0753 and IFT57) and related the clinical spectrum of four genes in other ciliopathies (C5orf42, TMEM138, TMEM231 and WDPCP) to OFDS. Mutations were also detected in two genes previously implicated in OFDS. Functional studies revealed the involvement of centriole elongation, transition zone and intraflagellar transport defects in OFDS, thus characterising three ciliary protein modules: the complex KIAA0753-FOPNL-OFD1, a regulator of centriole elongation; the Meckel-Gruber syndrome module, a major component of the transition zone; and the CPLANE complex necessary for IFT-A assembly. OFDS now appear to be a distinct subgroup of ciliopathies with wide heterogeneity, which makes the initial classification obsolete. A clinical classification restricted to the three frequent/well-delineated subtypes could be proposed, and for patients who do not fit one of these three main subtypes, a further classification could be based on the genotype