290 research outputs found

    Another new species of the genus Habrophlebia Eaton, 1881 (Ephemeroptera, Leptophlebiidae) from the Maghreb.

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    A new species belonging to the genus Habrophlebia Eaton, 1881 is described at the nymphal stage from the Rif Mountains of Morocco. This species presents unique features, such as the chorionic arrangement of the egg and the ornamentation of the posterior margin of abdominal tergites. It is compared to all west European Habrophlebia species and a table with discriminating characters is given. A phylogenetic reconstruction based on COI sequences fully supports the hypothesis of a new species in the Rif Mountains, with possible further distribution in southern Spain

    A new species of the genus Alainites Waltz & McCafferty, 1994 (Ephemeroptera, Baetidae) from the north of Morocco.

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    A new species of Alainites is described from northern of Morocco Alainitesalbaisp. nov. It can be separated from the other west Palearctic species by the gill number, the spination of the distal margin of tergites, the leg setation, and the paraproct shape and spination. This species is widespread in the study area but never abundant. It prefers small to medium streams with slow flow, and does not seem to be very sensitive to pollution and water logging activities

    Impact du zooplancton métazoaire sur le phytoplancton et les protozoaires ciliés dans le réservoir Sahela (Maroc)

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    L'impact du zooplancton métazoaire sur le phytoplancton et les protozoaires ciliés a été mesuré durant la période de juillet à décembre 1999 dans le réservoir Sahela sous climat méditerranéen semi-aride.Les expériences ont été réalisées à l'aide de chambres de diffusion immergées in situ pendant 7 heures en absence (chambres témoins) et en présence (chambres expérimentales) du zooplancton.Les résultats indiquent que la mortalité moyenne à 4 m des algues est de 0,13 + 0,03 h-1, et celle des protozoaires ciliés de 0,07 + 0,03 h-1. Cryptomonas ovata et Halteria grandinella ont subi la plus forte prédation, respectivement, 0,31 + 0,14 h-1 et 0,11 + 0,04 h-1 à 4 m. Toutefois, les algues de grande taille (Pediastrum sp, Ceratium hirundinella et Peridinium cinctum) n'ont été que très peu ou pas consommées.The Sahela reservoir, located in Taounate at 90 km from Fès, lying at an altitude of 325 m, was built to provide drinking water for the population of Taounate and to contribute to irrigate neighbouring farming perimeters.In order to assess the impact of metazoan zooplankton on phytoplankton and protozoan ciliates in the Sahela reservoir under semi-arid climate, we conducted experiments during the period from July to December 1999 at the deepest point in the lake (15 m).Sampling and measurements were carried out in diffusion chambers submerged in situ over a period of 7 h without (control chambers) and with (experimental chambers) zooplankton. During these experiments, counts were conducted on phytoplankton and ciliates to determine the abundance and the mortality of these organisms due to zooplankton in each diffusion chambers at t=0 and t=7 h incubation. The metazooplankton were counted and dry weight of each taxa was calculated.In summer the highest zooplankton biomass (150 µg·L-1) mainly composed of cyclopoid Tropocyclops prasinus, caused mortality of the small-sized ciliates, such as Halteria grandinella (0.10 h-1). In Autumn, the zooplankton biomass (75 µg·l-1), dominated by Daphnia longispina, induced a higher mortality for phytoplankton (0.10 h-1) than for ciliates (0.05 h-1). In Winter, the zooplankton biomass (100 µg·L-1), also represented by Daphnia longispina, had a low impact on ciliate mortality (< 0.02 h-1).The study showed that a heavy predation by the metazoan zooplankton was exerted on small-sized phytoplankton and ciliates and clearly demonstrated the relationships between protozoans and metazoan zooplankton to transfering the matter and energy in aquatic food webs

    LES BIO-ESSAIS DANS L’ÉVALUATION D’IMPACT DES POLLUANTS SUR LES ÉCOSYSTÈMES DULÇAQUICOLES

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    Les bioessais écotoxicologiques constituent un outil de choix dans le domaine de l’évaluation des effets des polluants sur la composante biologique des écosystèmes, ils traduisent les teneurs analysés par des outils de la chimie conventionnelle en effets mesurables sur des variables biologiques chez des populations des organismes tests. Plusieurs espèces, représentatives des écosystèmes aquatiques ou terrestres, ont fait l’objet de normalisation pour l’évaluation de la toxicité aiguë et/ou chronique. A cet égard, le cladocère Daphnia magna Straus est un organisme test qui occupe une place confirmée pour l’évaluation de la toxicité aiguë et chronique de polluants sur les écosystèmes d’eau douce. Cette espèce est choisie en raison de son rôle clé dans la chaîne trophique, sa sensibilité, sa facilité d’élevage et son cycle de vie qui est mis à profit pour le test de reproduction de 21 jours. Outre la détermination des CE50 dans des essais de toxicité aiguë (24 ou 48 H), l’étude de la toxicité chronique permet la détermination de la LOEC (Lowest effect concentration) et de la NOEC (No effect concentration) qui sont des valeurs remarquables adoptées dans les études d’évaluation de risque de nouvelles molécules par les instances de réglementation internationales

    Gravitational Waves from Preheating in Gauss-Bonnet Inflation

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    We study gravitational wave production in an expanding Universe during the first stages following inflation, and investigate the consequences of the Gauss-Bonnet term on the inflationary parameters for a power-law inflation model with a GB coupling term. Moreover, we perform the analyses on the preheating parameters involving the number of e-folds NpreN_{pre}, and the temperature of thermalization Tth,T_{th}, and show that it's sensitive to the parameters nn, and γ\gamma, the parameter γ\gamma is proposed to connect the density energy at the end of inflation to the preheating energy density. We set a correlation of gravitational wave energy density spectrum with the spectral index nsn_{s} detected by the cosmic microwave background experiments.. The density spectrum Ωgw\Omega_{gw} shows good consistency with observation for γ=103\gamma = 10^{3} and 10610^{6}. Our findings suggest that the generation of gravitational waves (GWs) during preheating can satisfy the constraints from Planck's data

    Two new species of Centroptilum Eaton, 1869 from North Africa (Ephemeroptera, Baetidae).

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    Based on recently collected larvae from Algeria and Morocco, the species delimitation within the genus Centroptilum Eaton, 1869 in that region is validated. Two new species are described and illustrated, one from north-eastern Algeria, and one from North Morocco, using an integrated approach with morphological and molecular evidence. A table summarising the morphological differences between the new species and Centroptilumluteolum (Müller, 1776) from Central Europe is provided. Further, molecular evidence for additional undescribed species of Centroptilum in other regions of the West Palearctic is provided and discussed

    Dark matter via Baryogenesis: Affleck-Dine Mechanism in the Minimal Supersymmetric Standard Model

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    We conducted an investigation into Affleck-Dine baryogenesis within the context of D-term inflation, specifically focusing on its relationship with a recent reheating formalism. It was found that by considering a specific reheating temperature, the observed baryon asymmetry can be accounted through Affleck-Dine baryogenesis. Additionally, the majority of gravitinos are inferred to be generated from the decay of the next-to-lightest supersymmetric particle, with Q-balls potentially serving as a source of gravitinos via NSP decay. The temperature at which decay occurs depends on the charge of the Q-balls, which is determined by the fragmentation of the Affleck-Dine condensate. Remarkably, the gravitino mass required for dark matter aligns naturally with the theoretical gravitino mass.Comment: 11 pages, 4 figure

    Contribution à la connaissance des Trichoptères (Trichoptera) du Rif (Nord du Maroc)

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    L´étude de 6376 spécimens des Trichoptères récoltés dans 103 localités de la chaîne rifaine marocaine entre 2006 et 2010 et la compilation des citations bibliographiques concernant ce groupe d´insectes, ont permis l´identification de 41 espèces dans la zone. Cet inventaire faunistique a enrichi la faune du Rif de 7 espèces non citées antérieurement dans cette zone. Une check-list des Trichoptères identifiées est fournie et la distribution géographique à l´intérieur et à l´extérieur des bassins versants Rifains est discutée pour chacune des espèces, ainsi que quelques notes taxonomiques concernant quelques espèces

    Nuevos datos de tricópteros en ríos de referencia de clima mediterráneo en la Península Ibérica y norte de África: aspectos taxonómicos, faunísticos y ecológicos

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    Trichoptera is a very rich order in the Western Mediterranean, but knowledge of caddisflies in the Iberian Peninsula and northern Africa is still not complete. We present records of caddisflies collected in 114 sites of the Mediterranean climate region of the Iberian Peninsula and the western Rif. We also provide notes on ecological aspects and taxonomical remarks on some species. Atotal of 86 species were identified and 8 species extended their distribution range. Considering the four differentiated geological regions in the western Mediterranean Basin during the Tertiary, 60 species were collected in the Iberian plate region, 29 in the Transition, 30 in the Betic and 18 in the Rif. Local richness was not significantly different between the four regions but significant differences were found among several river ecotypes within regions. Temporary sites had lower local richness than other ecotypes in all regions except in the Rif, whereas headwaters had similar richness in any region regardless of their geology. The Rif region had the lowest Trichoptera richness, which is not only the result of the scarcity of faunistic studies in the area but also of the high frequency of temporary rivers and the isolation of the area. Our results suggest that conservation measures addressed to preserve the biodiversity of the Western Mediterranean should be enforced, especially in the Rif region.El orden Trichoptera es rico en especies en la zona del Mediterráneo Occidental, pero el conocimiento de este grupo en la Península Ibérica y el norte de África resta aún de ser completo. Presentamos datos de tricópteros recolectados en 114 localidades de la región Mediterránea de la Península Ibérica y del Rif occidental. Además, proporcionamos datos sobre la ecología de algunas especies así como notas taxonómicas. Se identificaron un total de 86 especies y el rango de distribución aumentó para 8 de ellas. Sesenta especies se recolectaron en la región de la placa Ibérica, 29 en la de Transición, 30 en la Bética y 18 en el Rif, las cuatro regiones geológicas diferenciadas durante el Terciario en el Mediterráneo Occidental. La riqueza local no fue significativamente diferente entre regiones geológicas, pero sí entre varios ecotipos fluviales. Los tramos temporales presentaron una riqueza local menor que los demás ecotipos, excepto en el Rif, mientras que las cabeceras presentaban una riqueza similar en cada región independientemente de su geología. Globalmente el Rif presentó una menor riqueza de tricópteros, lo que se explica no sólo por la escasez de estudios faunísticos en la zona sino también por la elevada frecuencia de ríos temporales y su aislamiento geográfico. Nuestros resultados sugieren que en la zona del Mediterráneo Occidental se deben de llevar a cabo medidas de conservación urgentes para preservar su biodiversidad, especialmente en la región del Rif

    Design and optimization of a new compact 2.4 GHz-bandpass filter using DGS technique and U-shaped resonators for WLAN applications

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    The objective of this work is the study, the design and the optimization of an innovative structure of a network of coupled copper metal lines deposited on the upper surface of a R04003 type substrate of height 0.813 with a ground deformed by slots (DGS). This structure is designed in an optimal configuration for use in the design of narrowband bandpass filter for wireless communication systems (WLAN), the aim of use the defected ground structure is to remove the unwanted harmonics in the rejection band, the simulation results obtained from this structure using CST software show a very high selectivity of the designed filter, a very low level of losses (less than-0.45 dB) with a size overall size of 43.5x34.3 mm
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