Recrutement des poissons dans le fjord du Saguenay

La faune ichtyologique du fjord du Saguenay est composée de plus de 60 espèces de poissons marins, diadromes et dulcicoles dont plusieurs font l’objet d’une pêche récréative comme l’éperlan arc-en-ciel anadrome (Osmerus mordax), le sébaste (Sebastes spp.), la morue franche (Gadus morhua), la morue ogac (Gadus ogac) et le flétan du Groenland (Reinhardtius hippoglossoides). On ignore si le recrutement des poissons marins exploités par la pêche récréative dans le Saguenay dépend de la production des stocks locaux ou des échanges avec les populations de l’estuaire du Saint-Laurent. Nous avons donc étudié la distribution spatio-temporelle de l’ichtyoplancton dans le fjord du Saguenay afin d’identifier les zones de production, de rétention et d’advection larvaires dans le but d’y préciser les mécanismes de recrutement des stocks de poissons. L’ichtyoplancton a été échantillonné à 21 stations sur le fjord du Saguenay à six occasions, de mai à octobre 2004, et à cinq occasions, de juin à septembre 2005. Les résultats montrent que le recrutement du capelan et de l’éperlan arc‑en‑ciel anadrome repose sur la production et la rétention des larves dans le fjord du Saguenay. Cependant, le recrutement des sébastes et des morues dépendrait de l’immigration de juvéniles en provenance de l’estuaire du Saint-Laurent. Ces résultats sont supportés par une revue des résultats des études antérieures sur les poissons du fjord du Saguenay. L’étude des mécanismes de recrutement des stocks de poissons du fjord du Saguenay favorise l’exploitation durable de ces ressources halieutiques conformément à la mission de Pêches et Océans Canada et dans le respect du programme de conservation du parc marin du Saguenay‑Saint-Laurent.In the Saguenay Fjord, the fish community is composed of more than 60 marine, diadromous and freshwater species, including many species exploited by the winter sport fishery such as the rainbow smelt (Osmerus mordax), redfish (Sebastes spp.), Atlantic cod (Gadus morhua), Greenland cod (Gadus ogac), and Greenland halibut (Reinhardtius hippoglossoides). We do not know if the recruitment of the fish species exploited by the winter sport fishery depends on the local production of recruits in the Saguenay Fjord or on exchanges with the St. Lawrence Estuary populations. Hence, we measured the spatio-temporal distribution of ichthyoplankton in the Fjord to identify zones of larval production, retention or advection, in order to investigate the recruitment mechanisms of these stocks. We sampled ichthyoplankton at 21 stations on six occasions, from May to October 2004, and on five occasions, from June to September 2005. Results indicated that the recruitment of capelin (Mallotus villosus) and of the anadromous rainbow smelt (Osmerus mordax) relied on the local production and retention of larvae within the Fjord. However, the recruitment of redfish (Sebastes spp.) and cods (Gadus spp.) depended on the immigration of juveniles from the St. Lawrence Estuary. Our results are corroborated by a review of previous studies of these fish populations. Studying the recruitment mechanisms of fish populations in the Saguenay Fjord supports a sustainable exploitation of these locally important fisheries resources, in accordance with the mission of Fisheries and Oceans Canada and consistent with the conservation program of the Saguenay St. Lawrence Marine Park

An Optimal Algorithm To Recognize Robinsonian Dissimilarities

International audienceA dissimilarity D on a finite set S is said to be Robinsonian if S can be totally ordered in such a way that, for every $i < j < k, D(i, j) ≤ D(i, k)$ and $D(j, k) ≤ D(i, k)$. Intuitively, D is Robinsonian if S can be represented by points on a line. Recognizing Robinsonian dissimilarities has many applications in se-riation and classification. In this paper, we present an optimal $O(n 2)$ algorithm to recognize Robinsonian dissimilarities, where n is the cardinal of S. Our result improves the already known algorithms

First radial velocity results from the MINiature Exoplanet Radial Velocity Array (MINERVA)

The MINiature Exoplanet Radial Velocity Array (MINERVA) is a dedicated observatory of four 0.7m robotic telescopes fiber-fed to a KiwiSpec spectrograph. The MINERVA mission is to discover super-Earths in the habitable zones of nearby stars. This can be accomplished with MINERVA's unique combination of high precision and high cadence over long time periods. In this work, we detail changes to the MINERVA facility that have occurred since our previous paper. We then describe MINERVA's robotic control software, the process by which we perform 1D spectral extraction, and our forward modeling Doppler pipeline. In the process of improving our forward modeling procedure, we found that our spectrograph's intrinsic instrumental profile is stable for at least nine months. Because of that, we characterized our instrumental profile with a time-independent, cubic spline function based on the profile in the cross dispersion direction, with which we achieved a radial velocity precision similar to using a conventional "sum-of-Gaussians" instrumental profile: 1.8 m s$^{-1}$ over 1.5 months on the RV standard star HD 122064. Therefore, we conclude that the instrumental profile need not be perfectly accurate as long as it is stable. In addition, we observed 51 Peg and our results are consistent with the literature, confirming our spectrograph and Doppler pipeline are producing accurate and precise radial velocities.Comment: 22 pages, 9 figures, submitted to PASP, Peer-Reviewed and Accepte

An Optimal Algorithm To Recognize Robinsonian Dissimilarities

International audienceA dissimilarity D on a finite set S is said to be Robinsonian if S can be totally ordered in such a way that, for every $i < j < k, D(i, j) ≤ D(i, k)$ and $D(j, k) ≤ D(i, k)$. Intuitively, D is Robinsonian if S can be represented by points on a line. Recognizing Robinsonian dissimilarities has many applications in se-riation and classification. In this paper, we present an optimal $O(n 2)$ algorithm to recognize Robinsonian dissimilarities, where n is the cardinal of S. Our result improves the already known algorithms

10 W-level gain-switched all-fiber laser at 2.8 μm

We report a simply designed gain-switched all-fiber laser emitting a maximum average output power of 11.2 W at 2.826 μm. The corresponding extracted pulse energy is 80 μJ at a pulse duration of 170 ns. These performances significantly surpass previous gain-switched demonstrations and are close to the state-of-the-art Q-switched laser performances near 2.8 μm, but with a much simpler and robust all-fiber design. The spliceless laser cavity is made of a heavily erbium-doped fluoride glass fiber and is bounded by fiber Bragg gratings written directly in the gain fiber through the protective polymer coating

Periodic Chronic Myelogenous Leukaemia: Spectral Analysis of Blood Cell

Summary. Of 24 published clinical reports of periodic chronic myelogenous leukaemia (PCML), 21 had sufficient data to analyse for periodicity, and 12 showed significant periodicity ( p р 0·05) using the Lomb periodogram. Leucocyte oscillations had periods T ranging from 37 to 83 d. When data were also reported for platelets and reticulocytes there was no significant difference between their periods and those of the leucocytes. These data and their analysis provide strong circumstantial evidence for a haemopoietic stem cell origin of PCML. Namely, the known chromosomal changes in CML patients may, on occasion, also be accompanied by a destabilization resulting in an oscillatory efflux into the leucocyte, platelet and erythrocytic pathways