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Numerical Modeling of Mass Transfer in the Interaction between River Biofilm and a Turbulent Boundary Layer

Open Journal of Fluid Dynamics 2024年第1期14卷 1-23页

作者： Falilou Coundoul Evrad M. D. Ngom Frédéric Y. Moulin Institut Polytechnique de Saint-louis Université Gaston Berger Saint-Louis Senegal Institut de Mécanique des Fluides de Toulouse UMR 5502-Université de Toulouse Occitanie France

In this article dedicated to the modeling of vertical mass transfers between the biofilm and the bulk flow, we have, in the first instance, presented the methodology used, followed by the presentation of various results obtained through analyses conducted on velocity fields, different fluxes, and overall transfer coefficients. Due to numerical constraints (resolution of relevant spatial scales), we have restricted the analysis to low Schmidt numbers (Sc=0.1, Sc=1, and Sc=10) and a single roughness Reynolds number (Re*=150). The analysis of instantaneous concentration fields from various simulations revealed logarithmic concentration profiles above the canopy. In this zone, the concentration is relatively homogeneous for longer times. The analysis of results also showed that the contribution of molecular diffusion to the total flux depends on the Schmidt number. This contribution is negligible for Schmidt numbers Sc≥0.1, but nearly balances the turbulent flux for Sc=0.1. In the canopy, the local Sherwood number, given by the ratio of the total flux (within or above the canopy) to the molecular diffusion flux at the wall, also depends on the Schmidt number and varies significantly between the canopy and the region above. The exchange velocity, a purely hydrodynamic parameter, is independent of the Schmidt number and is on the order of 10% of in the present case. This study also reveals that nutrient absorption by organisms near the wall depends on the Schmidt number. Such absorption is facilitated by lower Schmidt numbers.

关键词： Epilithic Biofilm Passive Scalar Transport Direct Numerical Simulation Navier-Stokes

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Effect of High-Speed Solar Winds Turbulence Upstream of the Earth’s Magnetosphere: Case of the Outer Minima of Solar Cycles 20, 21, 22, 23 and 24

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Open Journal of Applied Sciences 2023年第7期13卷 1145-1162页

作者： Inza Gnanou Salfo Kabore Aristide Marie Frédéric Gyebre Christian Zoundi Jean-louis Zerbo Frédéric Ouattara É cole Normale Supérieure Koudougou Burkina Faso Department of Physics Laboratoire de Recherche en énergétique et Météorologie de l’Espace (LAREME) Université Norbert ZONGO Koudougou Burkina Faso Department of Physics Laboratoire de Matériaux d’Héliophysique et Environnement (LaMHE) Université Nazi BONI Bobo-Dioulasso Burkina Faso

Highly turbulent environment, the solar wind is a stream of very energetic particles mainly made of protons and electrons. During its trip in the interplanetary space, this solar flow becomes more accelerated during the outer minima (descending phases) of the solar cycles and can therefore influence all of humanity and its technology. These disturbances lead to socio-economic consequences requiring a precise knowledge of the climate variability. Using a statistical approach, we evaluate the response of the Earth’s magnetosphere to the High-Speed Solar Winds (HSSW) forcing during the peaks of the last five outer minima. To do so, 1UA data of solar wind and magnetic field parameters were extracted from OMNI browser. Analysis of the energetic solar plasma particles shows that strong geomagnetic field variations can occur even in the absence of large solar disturbances. While the normalized reconnection rate was estimated to be ~21% of the total variance of the magnetospheric variables, the upstream of the magnetic cavity was perturbed 80% of the time with large energies recorded. As a result, Earth’s magnetosphere becomes denser (i.e., more drag), which is a problem for spacecraft. Thus, the coupled solar wind-magnetosphere system follows scale-invariant dynamics and is in a state far from equilibrium. Our analysis provides insight into the main cause of geomagnetic storms with more than 97% of HSSW imposed in the range 300 - 850 km/s. These high-speeds lead to auroras that can disrupt electrical and communication systems.

关键词： Solar Wind Outer Minimum Magnetosphere Geomagnetic Field Solar Disturbances

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Comparative transcriptomics of anadromous and resident brook charr Salvelinus fontinalis before their first salt water transition

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Current Zoology 2012年第1期58卷 158-170页

作者： Boulet, Marylène Normandeau, Éric Bougas, Bérénice Audet, Céline Bernatchez, louis IBIS (Institut de Biologie Intégrative et des Systèmes) Université Laval Québec QC G1V 0A6 Canada ISMER Université du Québec à Rimouski Rimouski QC G5L 3A1 Canada

Most salmonid taxa have an anadromous life history strategy, whereby fish migrate to saltwater habitats for a growth period before returning to freshwater habitats for spawning. Moreover, several species are characterized by different life history tactics whereby resident and anadromous forms may occur in genetically differentiated populations within a same species, as well as polymorphism within a population. The molecular mechanisms underlying the physiological differences between anadromous and resident forms during the first transition from freshwater to saltwater environments are only partially understood. Insofar research has typically focused on species of the genusSalmo. Here, using a 16,000 cDNA array, we tested the hypothesis that ana-dromous brook charrSalvelinus fontinalisare characterized by differences in their transcriptome relative to resident brook charr before the anadromous fish migration. Families originating from parapatric populations of anadromous and resident charr were reared in controlled environments mimicking natural temperature and photoperiod, and sampled in spring, while still in fresh water. While anadromous and resident charr showed similar transcriptome profiles in white muscle, they were characterized by striking differences in their gill transcriptome profiles. Genes that were upregulated in the gills of anadromous charr were principally involved in metabolism (mitochondrial electron transport chain, glucose metabolism, and protein synthesis), development (tissue differentiation) and innate immunity. We discuss the nature of these transcriptomic differences in relation to molecular mechanisms underlying the expression of anadromous and resident life history tactics and suggest that the anadromous charr express some of the molecular processes present in other migratory salmonids.

关键词：居民生活红点鲑转录生活史策略咸水 cDNA阵列分子机制海水环境

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Comment on “Locating the source field lines of Jovian decametric radio emissions” by YuMing Wang et al.

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Earth and Planetary Physics 2022年第1期6卷 10-12页

作者： Laurent Lamy Baptiste Cecconi Stéphane Aicardi C.K.louis LESIA Observatoire de ParisUniversitéPSLCNRSSorbonne UniversitéUniversitéde Paris5 place Jules Janssen92195 MeudonFrance Station de Radioastronomie de Nançay Observatoire de ParisUniversitéPSLCNRSUniv.Orléans18330 NançayFrance LAM PythéasAix Marseille UniversitéCNRSCNES38 Rue Frédéric Joliot Curie13013 MarseilleFrance DIO UMS2201 CNRSObservatoire de ParisUniversitéPSL61 avenue de l’Observatoire75014ParisFrance School of Cosmic Physics DIAS Dunsink ObservatoryDublin Institute for Advanced StudiesDublinIreland

In this comment on the article“Locating the source field lines of Jovian decametric radio emissions”by Wang YM et al.,2020,we discuss the assumptions used by the authors to compute the beaming angle of Jupiter’s decametric emissions induced by the moon *** method,relying on multi-point radio observations,was applied to a single event observed on 14th March 2014 by Wind and both STEREO A/B spacecraft from~5 to~16 *** have erroneously identified the emission as a northern(Io-B type)instead of a southern one(Io-D type).We encourage the authors to update their results with the correct hemisphere of origin and to test their method on a larger sample of Jupiter-Io emissions.

关键词： planetary magnetosphere Jupiter auroral radio emissions planet-moon interaction

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Annual and Diurnal Variabilities in the Critical Frequency (foF2) during Geomagnetic Fluctuating Activity over Solar Cycles 21 and 22 at Ouagadougou

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Atmospheric and Climate Sciences 2018年第4期8卷 435-445页

作者： Abidina Diabaté Frédéric Ouattara Jean louis Zerbo Laboratoire de Recherche en Energétique et Météorologie de l’Espace (LAREME) Université Norbert Zongo Koudougou Burkina Faso Université Nazi Boni Bobo Dioulasso Burkina Faso Laboratoire d’Energies Thermiques Renouvelables (L.E.T.RE) Université Ouaga 1 Pr Joseph Ki-Zerbo Ouagadougou Burkina Faso

Geomagnetic activity is characterized by four solar wind conditions. Each condition has specific impact on ionosphere. This paper review on fluctuating activity effects on ionosphere F2 layer through its critical frequency foF2 variations. Under fluctuating wind conditions, we have investigated on annual, diurnal and seasonal variations of foF2 during solar cycles 21 and 22 phases covered by Ouagadougou ionosonde station data (Lat: 12.5°N;Long: 358.5°E;dip: 1.43°). Our investigations show that foF2 annual’ variability is in phase with solar cycle. The diurnal variation is “noon bite out” most of the time except for the solar maximum where we have a morning peak testifying to the fact that the vertical drift E × B is disturbed. The seasonal variations show that the fluctuating activity has no particular effect on certain characteristics of the equatorial ionosphere such as electrojet and vertical drift E × B. However, the increase of the electric field pre-reversal phenomenon in autumn is a characteristic effect observed during the fluctuating activity.

关键词： Critical Frequency Solar Cycle Seasonal Diurnal Fluctuating Activity

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Integrating fossils in a molecular-based phylogeny and testing them as calibration points for divergence time estimates in Menispermaceae

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Journal of Systematics and Evolution 2011年第1期49卷 25-49页

作者： Frdric M.B. JACQUES Rosa Del C. ORTIZ Department of Biodiversity and Biogeography Kunming Institute of Botany Chinese Academy of Sciences State Key Laboratory of Systematic and Evolutionary Botany Institute of Botany Chinese Academy of Sciences Missouri Botanical Garden St. Louis MO 63166-0299 USA

The phylogeny of extant Menispermaceae (Ranunculales) is reconstructed based on DNA sequences of two chloroplast genes (rbcL and atpB) from 94 species belonging to 56 genera. Fossilized endocarps represent 34 genera. The positions of these are inferred using 30 morphological characters and the molecular phylogeny as a backbone constraint. Nine of the thirteen nodes that are each dated by a fossil are used as calibration points for the estimates of molecular divergence times. BEAST is used to estimate stem age (121.2 Myr) and crown age (105.4 Myr) for Menispermaceae. This method does not require an input tree topology and can also account for rate heterogeneity among lineages. The sensitivity of these estimates to fossil constraints is then evaluated by a cross-validation procedure. The estimated origin for Menispermaceae is dated to the mid-Jurassic if the customary maximum age of 125 Myr for eudicots is not implemented. All constraints when used alone failed to estimate node ages in some parts of the tree. Fossils from the Palaeocene and Eocene impose strict constraints. Likewise, the use of Prototinomiscium as a dating constraint for Menispermaceae appears to be a conservative approach.

关键词： age calibration cross-validation fossil Menispermaceae molecular scaffold phylogeny.

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Solar Activity and Meteorological Fluctuations in West Africa: Temperatures and Pluviometry in Burkina Faso, 1970-2012

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International Journal of Astronomy and Astrophysics 2013年第4期3卷 408-411页

作者： Jean-louis Zerbo Frédéric Ouattara Emmanuel Nanéma LERSEM University of Koudougou Koudougou Burkina Faso UFR/ST Polytechnic University of Bobo Dioulasso Bobo-Dioulasso Burkina Faso

In this paper we investigate the fluctuations of solar activity and their links with climatic parameters in West Africa. We achieve our research by investigating several data plotted using averages. Mean to our results we can assume that active solar is associated with weak incident cosmic ray consequently with low cloudiness which brings warming. Likewise, quiet solar is associated with important cloud cover and consequently brings important precipitations and chills terrestrial atmosphere. This implies the necessity to deal with space phenomenon by considering the severe interconnection between solar activity indices for interplanetary and earth environment weather forecasting.

关键词： Solar Activity Temperatures Precipitations Cloud Cover Solar Cycle

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Variability of the Critical Frequency foF2 for Equatorial Regions during Solar Cycle’s Minima and Maxima at Ouagadougou and Manila Stations

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International Journal of Geosciences 2019年第10期10卷 833-844页

作者： Kaboré M’Bi Zerbo Jean louis Zoundi Christian Ouattara Frédéric Laboratoire de Recherche en Energétique et Météorologie de l’Espace (LAREME) Université Norbert Zongo Koudougou Burkina Faso Laboratoire de Matériaux d’Héliophysique et Environnement (LAMHE) Université Nazi Boni Bobo Dioulasso Burkina Faso.

In this paper we report on the foF2 variabilities for two equatorial regions (Ouagadougou: Lat. 12.4°N;Long. 358.5°E, Dip. 1.43°S;and Manila: Lat. 14°36'15.12''N;Long. 120°58'55.92''E;Dip. 0.6°S) during solar cycles 20 and 21 minima and maxima phases. Many previous works have argued on the diurnal and seasonal variation of foF2 for different solar events conditions for latitudinal position. But there are few investigations for Africa equatorial region longitudinal variation. The present paper’s goal is to outline possible similarity in foF2 behavior between variations for better understanding of physical process lead to some observed phenomenon in Asia-Africa equatorial sector. The F-layer critical frequency (foF2) data observed from the two equatorial ionosonde stations have been used for the present comparative study. The results show significant similarity between the critical frequency (foF2) seasonal variations over the time intervals 1976-1996. During day-time measured data from Manila station are higher than those from Ouagadougou station. That may lie in that Manila is closer to equatorial ionization crest region. During solar minimum phase, the longitudinal variation of foF2 shows two crossing points (11:00 UT and 22:00 UT) between the foF2 profiles form the two stations for all seasons regardless of the solar cycle. However during intense solar activity condition, the number of crossing-point between measured data from Manila and Ouagadougou stations varies by seasons and solar cycle. This phenomenon may be due to the compilations of severe activities (storms, coronal mass ejection, heliosheet fluctuations) during the solar maximum phases.

关键词： Critical Frequency (foF2) Longitudinal Variation Seasonal Solar Cycle

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Analysis of Spatio-Temporal Dynamics of Land Use in the Bouba Ndjidda National Park and Its Adjacent Zone (North Cameroun)

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Open Journal of Forestry 2020年第1期10卷 39-57页

作者： José Elvire Boukeng Djiongo André Desrochers Marie louise Tiencheu Avana Damase Khasa louis Zapfack éric Fotsing Department of Wood and Forest Sciences Faculty of Forestry Geography and Geomatics Laval University Quebec Canada Garoua Wildlife School Garoua Cameroun Department of Forestry Faculty of Agronomy and Agricultural Sciences University of Dschang Dschang Cameroon Department of Plant Biology Faculty of Sciences University of Yaoundé 1 Yaoundé Cameroon Department of Computer Engineering University Institute of Technology Fotso Victor University of Dschang Bandjoun Cameroon

We evaluated the dynamics of land use in the Bouba Ndjidda National Park (BNNP) and adjacent areas, in northern Cameroon. Using a maximum likelihood supervised classification of satellite images from 1990 to 2016, coupled with field and a socio-economic survey, we performed a robust land-use classification. Between 1990 and 2016, the area included eight classes of land use, with the largest in 1990 being the woody savannah (42.9%) followed by the gallery forest (20.2%) and the clear forest (16.3%). Between 1990 and 1999, the gallery forest lost 64.8% of its area mostly to the benefit of woody savannahs. Between 1999 and 2016, the largest loss of area was that of the clear forest, which decreased generally by 43.2% in favor of woody savannah. Rates of increase of crop field areas were 59.6% and 78.8% respectively for the periods of 1990 to 1999 and 1999 to 2016 to the detriment of woody savannahs. We attribute the changes in land use observed mainly to the increasing human population and associated agriculture, overgrazing, fuelwood harvesting and bush fires. The exploitation of non-timber forest products and climatic factors may also have changed the vegetation cover. We recommend the implementation of farming techniques with low impact on the environment such as agroforestry.

关键词： Remote Sensing Spatio-Temporal Dynamics Bouba Ndjidda National Park Vegetation Cover Land Use

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Solar Activity, Solar Wind and Geomagnetic Signatures

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Atmospheric and Climate Sciences 2013年第4期3卷 610-617页

作者： Jean-louis Zerbo Frédéric Ouattara Christine Amory Mazaudier Jean-Pierre Legrand John D. ric.ardson Ecole Normale Supérieure de l’Université de Koudougou Koudougou Burkina Faso Institut National des Sciences de l’Univers (INSU) Paris France Kavli Institute for Astrophysics and Space Research Massachusetts Institute of Technology Cambridge USA LPP-Laboratoire de Physique des Plasmas/UPMC/Polytechnique/CNRS Saint-Maur-des-Fossés France Université Polytechnique de Bobo-Dioulasso Bobo-Dioulasso Burkina Faso

The present study investigates solar events through geomagnetic activity and physical processes on the Sun: 1) Quiet activity (QA) related to the slow solar wind, 2) Recurrent activity (RA) related to high and moderate speed solar wind streams from coronal holes, 3) Shock activity (SA) identified by observations of SSCs and 4) Unclear activity (UA) which contains all activity not covered by the first three cases. For recent cycles, we analyze and emphasize some important results: Quiet activity is predominant for cycle 23, comprising 40% of the total activity and over 80% of the activity near solar minimum. Shock and recurrent activity contributions to total geomagnetic activity are largest in cycle 20. The most fluctuating events are observed during cycles 21 and 22. Throughout solar cycle 23, the contribution, from each type of activity, differs from recent solar cycles, with larger percentages of quiet and recurrent activity and less unclear activity. These percentages are similar to those in solar cycles observed in the late 1800s. Since 1963, solar wind data are available. We analyze the distribution of the solar wind velocity for each geomagnetic class of activity and find that: 1) Within each activity type aa does not depend on V, 2) Approximately 80% of the solar wind has V 450 km/s for RA, 3) SA and UA both have 60% of the solar wind V > 450 km/s. We found the following conditions for all four solar cycles: 1) For QA 95% of solar wind speeds are in the range 399 ± 69 km/s, 2) For RA 95% of the solar wind speeds range from 582 ± 110 km/s, 3) For SA 95% of the solar wind velocities are order of 482 ± 101.4 km/s, and 4) For UA 95% of solar wind speeds are 480 ± 85.82 km/s. These results confirm the classification scheme that QA reflects slow wind effects, RA effects high wind stream and UA answers to the fluctuations between high wind stream (~60%) and slow wind (~40%). The study shows that high wind stream (

关键词： Solar Wind Geomagnetic Activity Solar Activity Geomagnetic Index aa

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