The genetic role of dykes on the mineralization of the Monsabrais sector, Blake River Group, Abitibi greenstone belt

Le secteur de Monsabrais est un centre volcano-plutonique situé au nord-ouest du Groupe de Blake River. Il est situé entre les réseaux de failles internes et externes de la caldeira de Misema, basée sur le modèle de méga-caldeira pour le Groupe de Blake River. La présence d'une séquence volcanique recoupée par un essaim de dykes radiaux et concentriques autour de la suite plutonique de Monsabrais est un facteur clé du secteur. Cet environnement est généralement très favorable pour la formation de minéralisations volcanogènes. Le projet avait pour objectif principal la mise en place et le rôle génétique des dykes sur la minéralisation. Une série de techniques ont été utilisées: cartographie et échantillonnage, étude pétrographique des échantillons frais, altérés et minéralisés, lithogéochimie des dykes et des roches encaissantes, et étude des sulfures basée sur la signature des éléments traces analysés par LA-ICP-MS. Comme résultat de l'application de ces techniques, il est possible de déterminer le caractère co-magmatique de ce système volcano-plutonique de composition intermédiaire et d'affinité magmatique transitionnelle. Les lithologies intrusives sont: dykes majeurs, dykes équigranulaires, dykes porphyriques, la suite plutonique de Monsabrais et les dykes aplitiques. Les dykes majeurs sont interprétés comme des conduits d'alimentation de la séquence volcanique. La suite plutonique de composition gabbroique à granodioritique recoupe les unités précédentes. Les dykes aplitiques de composition granodioritique à granitique sont une phase plus felsique et tardive du pluton. Les dykes équigranulaires et porphyriques recoupent les autres lithologies, et ont la même composition que le pluton, mais se distinguent texturalement par leur granulométrie plus fine. L'altération hydrothermale a une distribution diffuse interprétée comme résultant de la superposition de zones d'altération semi-conformes. Les zones d'altération sont envahissantes et se manifestent sous la forme des minéraux suivants: quartz, épidote, chlorite et carbonate. Les veines de quartz-carbonates sont considérées comme étant syn-génétiques à l'altération hydrothermale. Ces modifications sont la conséquence de l'action des fluides hydrothermaux et du lessivage d'éléments dans une zone distale suivi par leur précipitation dans une zone proximale plus chaude. La source du fluide est interprétée comme étant l'eau de mer chauffée et possiblement des fluides hydrothermaux tardifs provenant de la suite plutonique. La minéralisation est représentée par la présence de pyrite, de pyrrhotite et de chalcopyrite sous trois formes: disséminée dans la matrice de la roche, en remplissage d'amygdules et moins communément dans les veines de quartzcarbonate. La classification texturale des pyrites met en évidence deux familles qui partagent les mêmes signatures géochimiques. La pyrrhotite a une signature géochimique similaire à celle des pyrites, attestant que les sulfures résultent d'un même événement hydrothermal. De plus, ces textures et signatures géochimiques sont comparables à celles d'autres gisements volcanogènes connus. Le modèle d'évolution définit le complexe de Monsabrais comme un événement magmatique formé en deux étapes. Un premier événement extrusif responsable de la formation de la séquence volcanique, où les dykes majeurs étaient des conduits nourriciers du magma. Le deuxième événement magmatique est responsable de la mise en place de la suite plutonique. Les autres dykes sont mis en place pendant les deux événements. Ces caractéristiques appuient la présence d'une ou plusieurs chambres magmatiques. L'activité hydrothermale résulte pour la plupart de la percolation d'eau de mer durant l'édification volcanique sous marine. - The Monsabrais area is a volcano-plutonic center located at the Northwest of the Blake River Group. It is situated between the inner and outer ring faults of the interpreted Misema Caldera based on the mega caldera complex model for the Blake River. The presence of a volcanic sequence intruded by a swarm of radial and concentric dykes within the plutonic suite of Monsabrais is the key features of the sector, and commonly very favourable for volcanogenic mineralization. The project had for main objective the establishment of the genetic role of the dykes on the mineralization. A series of techniques were used: mapping and sampling, pétrographie study of fresh and altered and mineralized samples, lithogeochemistry of dykes and host rocks and sulfide studies based on trace element signature yields by LA-ICP-MS. As result of the application of those techniques, it is possible to determine the co-magmatic character of this predominant intermediate, transitional magmaticvolcanic system. The intrusive lithologies are: major dykes, equigranular dykes, porphyritic dykes, Monsabrais plutonic suite and aplitic dykes. The major gabbroic dykes are interpreted as feeder conduits for the volcanic sequence. The gabbro to granodiorite plutonic suite crosscuts the precedent units. The granodiorite to granite aplitic dykes are a late and felsic phase from the pluton. The equigranular and porphyritic dykes have the same plutonic composition but a finer granulometry and occur crosscutting the other lithologies. The hydrothermal alteration has a random distribution interpreted as resulting from the analogous overprinting of semi-conformable alteration zones. The alteration zones are represented by the pervasive alteration of the following minerals: quartz, epidote, chlorite and carbonate. The quartz-carbonate veins are considered as related to the alteration zone genesis. Those alterations are the consequence of the distal leaching of elements from the rocks by hydrothermal fluids and the following precipitation of those elements in a proximal, hotter zone. The fluid source is interpreted as heated sea water and possibly later magmaticfluids from the plutonic suite. The mineralization is manifested by the occurrence of pyrite, pyrrhotite and chalcopyrite that occur on the area in three forms: disseminated in the whole rock, filling amygdules and less recurrent in quartz-carbonate veins. The pyrite defines texturally two families that share similar elemental signatures. The pyrrhotite has similar elemental signature to the pyrite families, evidencing that sulfides result from the same event. These are chemically and texturally comparable to other known volcanogenic deposits. Evolution model defines the Monsabrais complex as a two stage magmatic event. A first extrusive event is responsible for the formation of the volcanic sequence, fed by the major dykes. The second magmatic event is responsible for the plutonic suite emplacement. The other dykes are emplaced continuously during and between both events. Those features support the presence of one or more magmatic chambers in a volcanic center with complex and long evolution magmatism. Hydrothermal activity, mostly by seawater percolation was related to the volcanic edification under water

Possibilidades de autoformação docente em uma jornada narrativa

Este texto busca tecer considerações sobre uma jornada narrativa, de uma professora de matemática e formadora de professores, recentemente trilhada pela autora, em sua pesquisa de doutoramento. A partir de cinco percursos formativos, cada um com o objetivo de trazer preocupações e questionamentos típicos da docência e de como esta se caracteriza, seja na formação de professores, seja na educação básica, a jornada narrativa trouxe possibilidades de autoformação (transformação). Algumas destas possibilidades serão descritas neste trabalho, a título de resultado. Diversos artefatos foram utilizados, tais como aulas audiogravadas, e-mails, áudio do exame de qualificação, assim como as interferências de companheiros de jornada, para a produção de dados. Esta foi uma pesquisa com viés interpretativo realizada a partir de percursos metodológicos, que se abriram diante da sistematização da investigação. Optou-se por uma apresentação insubordinada criativa, como uma postura epistemopolítica diante do que é pesquisar junto ao professor de matemática e, a partir dele mesmo, como foi o caso. Pesquisas deste tipo trazem toda a complexidade de dentro da escola para o meio acadêmico: afinal, tenta responder, ainda que parcialmente, como nos tornamos os professores que somos hoje

Bacillus subtilis no biocontrole de Ceratocystis fimbriata em mudas de Acacia mearnsii

The aim of this study was to evaluate the effect of Ceratocystis fimbriata isolates, obtained from Actinidia deliciosa (kiwifruit), on black wattle (Acacia mearnsii De Wild.) seedlings, the potential biological control exerted in vitro by Bacillus subtilis on C. fimbriata, and the in vivo effect of B. subtilis against C. fimbriata on black wattle seedlings. Isolates of C. fimbriata obtained and identified from kiwi plantations were used in pathogenicity tests on A. mearnsii seedlings. In vitro, the antagonistic potential of B. subtilis on the pathogen was analyzed by direct confrontation tests. To evaluate the effect of B. subtilis in vivo, black wattle seedlings were inoculated with Rhizolyptus® seven days before and after pathogen inoculation. On black wattle seedlings, C. fimbriata isolates caused 44,15% to 100% severity. Direct confrontation tests revealed that the strains were effective in the biological control of C. fimbriata isolates in vitro. In vivo, Rizolyptus® was not efficient in controlling C. fimbriata.O objetivo deste trabalho foi avaliar o comportamento de isolados de Ceratocystis fimbriata obtidos de kiwi (Actinidia deliciosa) em mudas de acácia-negra (Acacia mearnsii De Wild.), o potencial de biocontrole in vitro de Bacillus subtilis sobre C. fimbriata e o comportamento in vivo de B. subtilis contra C. fimbriata em mudas de acácia-negra. Isolados de C. fimbriata obtidos e identificados em plantios de kiwi foram utilizados em testes de patogenicidade em mudas de A. mearnsii. O potencial antagônico in vitro de B. subtilis sobre o patógeno foi analisado em testes de confrontação direta. Para avaliar o comportamento in vivo de B. subtilis, as mudas de acácia-negra foram inoculadas com Rizolyptus® sete dias antes e após a inoculação do patógeno. Nas mudas de acácia-negra os isolados de C. fimbriata exibiram percentuais de severidade que variam de 44,15% a 100%. Nos testes de confrontação direta as cepas mostraram-se eficientes no biocontrole in vitro sobre os isolados de C. fimbriata. In vivo, o produto Rizolyptus® não foi eficiente no controle de C. fimbriata

High Performance dynamic voltage/frequency scaling algorithm for real-time dynamic load management and code mobility

Modern cyber-physical systems assume a complex and dynamic interaction between the real world and the computing system in real-time. In this context, changes in the physical environment trigger changes in the computational load to execute. On the other hand, task migration services offered by networked control systems require also management of dynamic real-time computing load in nodes. In such systems it would be difficult, if not impossible, to analyse off-line all the possible combinations of processor loads. For this reason, it is worthwhile attempting to define new flexible architectures that enable computing systems to adapt to potential changes in the environment. We assume a system composed by three main components: the first one is responsible of the management of the requests arisen when new tasks require to be executed. This management component asks to the second component about the resources available to accept the new tasks. The second component performs a feasibility analysis to determine if the new tasks can be accepted coping with its real-time constraints. A new processor speed is also computed. A third component monitors the execution of tasks applying a fixed priority scheduling policy and additionally controlling the frequency of the processor. This paper focus on the second component providing a "correct" (a task never is accepted if it is not schedulable) and "near-exact" (a task is rarely rejected if it is schedulable) algorithm that can be applicable in practice because its low/medium and predictable computational cost. The algorithm analyses task admission in terms of processor frequency scaling. The paper presents the details of a novel algorithm to analyse tasks admission and processor frequency assignment. Additionally, we perform several simulations to evaluate the comparative performance of the proposed approach. This evaluation is made in terms of energy consumption, task rejection ratios, and real computing costs. The results of simulations show that from the cost, execution predictability, and task acceptance points of view, the proposed algorithm mostly outperforms other constant voltage scaling algorithms. © 2011 Elsevier Inc. All rights reserved.This work has been supported by the Spanish Government as part of the SIDIRELI project (DPI2008-06737-C02-02), COBAMI project (DPI2011-28507-C02-02) and by the Generalitat Valenciana (Project ACOMP-2010-038).Coronel Parada, JO.; Simó Ten, JE. (2012). High Performance dynamic voltage/frequency scaling algorithm for real-time dynamic load management and code mobility. Journal of Systems and Software. 85(4):906-919. https://doi.org/10.1016/j.jss.2011.11.284S90691985

Accelerated aging of onion seeds (Allium cepa L.) submitted to saturated salt solution

The objective of the present study was to evaluate the methodology of the accelerated aging test to evaluate the physiological potential of onion seeds, as well as verify the possibility of using unsaturated and saturated solutions of sodium chloride (NaCl) as an option for water uptake control in seeds during the test without reducing sensitivity. Five lots of onion seeds were tested for germination, seedling emergence, emergence speed and accelerated aging (periods of 24, 48, 72, or 96 hours, with or without the use of a saturated saline solution of NaCl). The use of unsaturated and saturated solutions of NaCl reduced water absorption by onion seeds during the accelerated aging test, resulting in a less pronounced rate of deterioration, and less drastic and more uniform results. The 48 hour treatment with unsaturated and saturated NaCl solutions is an option for use because it promotes a better classification of the onion seed lots at different vigor levels