To refine the assumption that the contrast threshold of the human eye(Crt)remains constant in general visibility theory,we integrated an artificial intelligence-based approach with a mechanistic model(AI-SD)to derive ...To refine the assumption that the contrast threshold of the human eye(Crt)remains constant in general visibility theory,we integrated an artificial intelligence-based approach with a mechanistic model(AI-SD)to derive the equivalent contrast threshold at 488 nm(C_(488))from remote sensing reflectance on a pixel-by-pixel basis.The derived C_(488) was then applied to estimate Secchi depth(Z_(sd)).We trained and validated the AI-SD model using an extensive fieldmeasured dataset(N=1577)encompassing oceanic,coastal,and inland waters and compared its performance with a traditional mechanistic model.Our findings indicate that C_(488) theoretically ranges from 1.85×10^(−5) sr^(−1) to 0.138 sr^(−1) and improves the accuracy of Z_(sd) estimates from field-measured or satellite-derived remote sensing reflectance(R_(rs))by over 10%compared to the traditional model.Furthermore,applying the AI-SD model to global R_(rs) data revealed that C_(488) exhibits spatial and temporal variability across the world’s oceans.We linked this variability to the observed,yet traditionally unexplained,non-monotonic relationship between Z_(sd) and solar zenith angle-related water-leaving radiance.These results highlight the potential for enhancing global water transparency monitoring via ocean color satellites by incorporating accurate,pixel-level C_(488) values.展开更多
At peak granulite-facies metamorphic conditions, lower continental crust is arguably fluxed by large amounts of two key low water activity fluids： （i） high-density CO2 and/or （ii） concentrated saline so- lutions....At peak granulite-facies metamorphic conditions, lower continental crust is arguably fluxed by large amounts of two key low water activity fluids： （i） high-density CO2 and/or （ii） concentrated saline so- lutions. These fluids are either internally-derived, generated by mineral reactions or dehydration melting or, notably for CO2, externally-derived, issued from the underlying mantle. Postmetamorphic evolution results in complete disappearance of these fluids, except for minute remnants preserved in minerals as fluid inclusions. Two major processes are involved： （i） at peak conditions, granitoid magmas form, migrate upward, and crystallize as shallow intrusions in the upper crust （mineralized porphyry types or reduced intrusions）; （ii） during the rapid decompression which almost systematically follows a period of post-peak isobaric cooling, especially for ultrahigh-temperature granulites （anticlockwise P-T paths）, quartz-carbonate megashear zones are formed by repeated periods of seismic activity. Seismic activity may continue until all free fluids have disappeared, resulting in the ultramylonites and pseudotachylites that are found in many granulite domes. A great majority of vein-type Au deposits worldwide occur in the above-mentioned settings or nearby. We suggest that the Au has been scavenged by the granulite fluids, then redistributed and concentrated during the formation of veins and related phenomena.展开更多
The formation of continents involves a combination of magmatic and metamorphic processes. These processes become indistinguishable at the crust-mantle interface, where the pressure-temperature（P-T）conditions of（ul...The formation of continents involves a combination of magmatic and metamorphic processes. These processes become indistinguishable at the crust-mantle interface, where the pressure-temperature（P-T）conditions of（ultra） high-temperature granulites and magmatic rocks are similar. Continents grow laterally, by magmatic activity above oceanic subduction zones（high-pressure metamorphic setting）, and vertically by accumulation of mantle-derived magmas at the base of the crust（high-temperature metamorphic setting）. Both events are separated from each other in time; the vertical accretion postdating lateral growth by several tens of millions of years. Fluid inclusion data indicate that during the high-temperature metamorphic episode the granulite lower crust is invaded by large amounts of low H2O-activity fluids including high-density CO2 and concentrated saline solutions（brines）. These fluids are expelled from the lower crust to higher crustal levels at the end of the high-grade metamorphic event. The final amalgamation of supercontinents corresponds to episodes of ultra-high temperature metamorphism involving large-scale accumulation of these low-water activity fluids in the lower crust.This accumulation causes tectonic instability, which together with the heat input from the subcontinental lithospheric mantle, leads to the disruption of supercontinents. Thus, the fragmentation of a supercontinent is already programmed at the time of its amalgamation.展开更多
Recalling some of the most important events and persons during his education and career, the author sketches his growth from a young engineer, educated in the sanctuary of solid state reactions, to an involved fully d...Recalling some of the most important events and persons during his education and career, the author sketches his growth from a young engineer, educated in the sanctuary of solid state reactions, to an involved fully devoted scientific career for the study of fluids in the deep Earth. Most important in this respect was the discovery of C02 inclusions in granulites, which triggered years of discussion on fluid- absent or fluid-assisted granulite metamorphism. To some extent, this debate is a continuation of the former granite controversy, but it shows also how the famous battle of ＂soaks against pontiffs＂ could have been easily avoided.展开更多
Fluid （and melt） inclusion studies have shown a marked devel- opment in the last decades, as indicated by the increasing number of papers and as covered under major themes in specialized meetings （e.g. ECROFI in Eu...Fluid （and melt） inclusion studies have shown a marked devel- opment in the last decades, as indicated by the increasing number of papers and as covered under major themes in specialized meetings （e.g. ECROFI in Europe, PACROFI in America, ACROFI in Asia）. However, a basic text book is lacking in current literature, available information being either somewhat outdated （e,g. Roedder, 1984） or scattered in multi-author ＂short course＂, mainly organized by the Mineralogical Societies of Canada, America or Europe. A result is that basic features of fluid inclusion studies, notably its key technique, microthermometry, and recently supplemented by micro Raman of infrared spectroscopy, is rarely taught in most universities, leaving the student alone to discover a field of study which has grown to the dimensions of a major science.展开更多
Interpretation of primary growth markers (modules) is neglected in sustainable resource management processes, yet it opens up prospects for long time series on tree crown development, necessary for their characterizat...Interpretation of primary growth markers (modules) is neglected in sustainable resource management processes, yet it opens up prospects for long time series on tree crown development, necessary for their characterization in the current context of climate change. This study aimed to assess the morphological variation of crown shoots in <i><span style="font-family:Verdana;">Parkia biglobosa</span></i><span style="font-family:Verdana;"> in the face of a changing environment. Axis growth modules of 420 individuals of different ages were retrospectively analyzed in the presence or absence of shading during the wet and dry seasons in seven localities in Cote d’Ivoire. The results showed that the developmental environment of individuals did not influence the growth modules dimensions (P > 0.05). However, module size remained significantly different between locations (P < 0.05). The southern part of the gradient is still favourable and has priority for the establishment of permanent plots. The modules morphology differs from the youngest to the oldest individuals (P < 0.05). The rainy season remains the ideal period for the implementation of agroforestry reforestation programmes based on this species (P < 0.05). </span><i><span style="font-family:Verdana;">Parkia biglobosa</span></i><span style="font-family:Verdana;"> is a monochasial sympod (Pseudo-monopod) with a relay axis that follows the Paul Champagnat architectural model in the young stage, and transits to the Wilhelm Troll model later in the adult and old stage. This information contributes to the understanding of the functioning of crown and the adaptation of this species to a varying environment. It could guide choice of suitable environment and ideal genotype for the implementation of a reforestation or agroforestry programme based on </span><i><span style="font-family:Verdana;">Parkia biglobosa</span></i><span style="font-family:Verdana;">.</span>展开更多
The rapid rate of deforestation in Cote d’Ivoire has led to loss of plant species diversity and also threatens some commercial tree species with extinction.Some reforestation and aff orestation has been completed.How...The rapid rate of deforestation in Cote d’Ivoire has led to loss of plant species diversity and also threatens some commercial tree species with extinction.Some reforestation and aff orestation has been completed.However,for some species,the numbers of surviving transplants has declined.Hence,it is necessary to develop properly adapted and resilient genotypes that can eff ectively support the programs of forest restoration.In this context we evaluated the eff ects of the provenances of seeds and of various treatments on the germination rates and on plant growth of four commercial trees species(Pycnanthus angolensis,Terminalia superba,Mansonia altissima and Pterygota macrocarpa).We analyzed these parameters for seeds of three provenances(Daloa,Akoupéand Daoukro)of four species and for thirty plants aged 6 months per provenance.Time to begin germination and time to reach maximum germination were similar among species,and were not infl uenced by either treatment or provenance.Untreated seeds and those soaked for 24 and 48 h in water at room temperature yielded the highest germination rates,irrespective of species or provenance.The one exception was P.angolensis,for which no germination was recorded.Within species,some provenances produced higher germination percentages than did others.No clear relationship was computed between the germination rate and the morphometric characteristics of the seeds which varied signifi cantly between provenances.Plant growth and morphological variability also depended greatly on provenance.Genetic factors might be implicated,therefore provenance trials should be undertaken and evaluated.Furthermore,molecular analysis should be undertaken to confi rm the implications of genetic factors and allow for genetic selection.展开更多
Fluid infiltration into retrograde granulites of the Southern Marginal Zone （Limpopo high grade terrain） is exemplified by hydration reactions, shear zone hosted metasomatism, and lode gold mineralisation. Hydration...Fluid infiltration into retrograde granulites of the Southern Marginal Zone （Limpopo high grade terrain） is exemplified by hydration reactions, shear zone hosted metasomatism, and lode gold mineralisation. Hydration reactions include the breakdown of cordierite and orthopyroxene to gedrite ＋ kyanite, and anthophyllite, respectively. Metamorphic petrology, fluid inclusions, and field data indicate that a low H2O-activity carbon-saturated CO2-rich and a saline aqueous fluid infiltrated the Southern Marginal Zone during exhumation. The formation of anthophyllite after orthopyroxene established a regional retrograde anthophyllite-in isograd and occurred at P-Tconditions of -6 kbar and 610 ℃, which fixes the minimum mole fraction of H20 in the CO2-rich fluid phase at ~ 0.1. The maximum H20 mole fraction is fixed by the lower temperature limit （~800 ℃） for partial melting at -0.3. C-O-H fluid calculations show that the CO2-rich fluid had an oxygen fugacity that was 0.6 log10 units higher than that of the fayalite-magnetite- quartz buffer and that the CO2/（CO2＋CH4） mole ratio of this fluid was 1. The presence of dominantly relatively low density CO2-rich fluid inclusions in the hydrated granulites indicates that the fluid pressure was less than the lithostatic pressure. This can be explained by strike slip faulting and/or an increase of the rock permeability caused by hydration reactions.展开更多
Soil microbial biomass carbon (MBC), β-glucosidase, acid phosphatase and fluorescein diacetate (FDA) activities and bacterial community structure were assessed in a long-term (26 years) experiment, at physiological s...Soil microbial biomass carbon (MBC), β-glucosidase, acid phosphatase and fluorescein diacetate (FDA) activities and bacterial community structure were assessed in a long-term (26 years) experiment, at physiological stages of sorghum growth, comparing different management methods for organic (manure, straw residues) and inorganic (urea) amendments at the INERA field station in Saria (Burkina Faso). Annual application of manure led to the highest soil microbial biomass and enzyme activities. Investigations indicated that only microbial biomass and β-glucosidase activities were affected during the cropping season. Phosphatase and FDA enzyme activities did not depend on the crop development stages. The application of N fertilizer modified phosphatase and FDA enzyme activities, the activities being higher in soils amended with N fertilizer. The bacterial community structure was analyzed by PCR-denaturing gradient gel electrophoresis (PCR-DGGE) targeting the eubacterial 16S rRNA gene. Cluster analysis of PCR-DGGE patterns showed two major clusters, the first containing the mineral fertilization and straw treatments and the second, the straw + urea, manure and manure + urea treatments. Sorghum grain yields were the highest for manure treatments. In this long-term experiment, applying straw did not produce a better grain yield than that obtained in the un-amended plot.展开更多
The aim of this study was to test the impact of Rhizophagus irregularis, an arbuscular mycorrhizal fungus (AMF), on durum wheat growth and soil microbial functionalities in a field inoculation trial conducted in Moroc...The aim of this study was to test the impact of Rhizophagus irregularis, an arbuscular mycorrhizal fungus (AMF), on durum wheat growth and soil microbial functionalities in a field inoculation trial conducted in Morocco. The results showed that i) the R. irregularis inoculum effectively improved wheat growth, ii) wheat growth promotion depended on the soil mycorrhizal infectivity and iii) functional abilities of soil microflora depended on AMF inoculation. This study confirms that field AMF inoculation can be proposed as an effective agronomic practice in wheat production and as a sustainable cultural practice to manage soil biofunctioning. To fully promote inoculation practices, a better knowledge of AMF ecology has to be acquired to better adapt AMF inoculation to environmental conditions, and thus warrant better yields and agricultural sustainability.展开更多
This study presents the ore texture, mineralogy and whole rock geochemistry of iron occurrence from the Edea North area located at the upper limit of the Nyong Unit, part of the Congo craton. This iron mineralization ...This study presents the ore texture, mineralogy and whole rock geochemistry of iron occurrence from the Edea North area located at the upper limit of the Nyong Unit, part of the Congo craton. This iron mineralization is of magnetite quartzite type enclosed by metamorphic rocks of the granulite facies. Two main facies have been identified over the study area including the banded and the massive facies. The mineralogical set of these facies is in majority represented by magnetite, quartz and pyroxene martite in addition to minor biotite, apatite, and amphibole. Magnetite presents as irregular and elongated minerals which can contain quartz inclusions of various shapes and sizes, as blasts clustering, around pyroxenes and isolated xenomorphic magnetite minerals in the silicate phases. Quartz varies from fine to coarse-grained and ribbon quartz. This indicates re-crystallization and deformation during metamorphism. Electron microprobe analysis on magnetite and martite show Fe2O3 contents that vary between 96.11 and 99.76. Whole rock chemical data showed that Fe-contents are as high as 62.9 wt%. The SiO2 content varies between 33.8 wt% and 51.2 wt%. Iron oxides and SiO2 are negatively correlated. Moreover, the low positive correlations between Al2O3 and HFSE, and LILE suggest a contribution of clastic materials in the protolith of studied materials. The samples show low contents of V, Cr, Ba, Zr with respect to igneous rocks. This may infer a sedimentary origin for the studied rocks;furthermore, these materials may have undergone hydrothermal alteration. The REE patterns reveal enrichment in LREE compared to HREE. Some samples show positive Eu (1.82) and other negative anomalies Eu (0.54 to 0.97). The lack of Ce anomalies suggests that the depositional environment of the Edea North iron occurrence was anoxic or suboxic. Overall, the Edea North iron occurrence may have undergone significant input from hydrothermal sources with imprints of the clastic during its deposition.展开更多
To distinguish species or populations using morphometric data is generally processed through multivariate analyses, in particular the discriminant analysis. We explored another approach based on the maximum likelihood...To distinguish species or populations using morphometric data is generally processed through multivariate analyses, in particular the discriminant analysis. We explored another approach based on the maximum likelihood method. Simple statistics based on the assumption of normal distribution at a single variable allows to compute the chance of observing a particular data （or sample） in a given reference group. When data are described by more than one variable, the maximum likelihood （MLi） approach allows to combine these chances to find the best fit for the data. Such approach assumes independence between variables. The assumptions of normal distribution of variables and independence between them are frequently not met in morphometrics, but improvements may be obtained after some mathematical transformations. Provided there is strict anatomical correspondence of variables between unknown and reference data, the MLi classification produces consistent classification. We explored this approach using various input data, and compared validated classification scores with the ones obtained after the Mahalanobis distance-based classification. The simplicity of the method, its fast computation, performance and versatility, make it an interesting complement to other classification techniques.展开更多
In this work we compared the effect of the growth regulator content of the culture medium on the growth of in vitro shoot tips of five yam accessions belonging to four yam species (one Dioscorea alata, one D. rotundat...In this work we compared the effect of the growth regulator content of the culture medium on the growth of in vitro shoot tips of five yam accessions belonging to four yam species (one Dioscorea alata, one D. rotundata, one D. cayenensis and two D. trifida). Medium S contained 0.6 μM benzyl adenine, 1.07 μM naphthalene acetic acid and 0.23 μM gibberellic acid while medium EBR contained 0.23 μM gibberellic acid and 0.1 μM 24-epibrassinolide. After 2 months of culture, oxidation level was significantly reduced on medium EBR compared to medium S for four of the five accessions tested. By contrast, medium EBR did not have any positive effect on shoot length since length of shoots produced after 2 months of culture on medium S and EBR were similar, except with accession 3-45T, for which shoot length was shorter on medium S compared to medium EBR. These results underline the potential of 24-epibrassinolide to reduce oxidation phenomena during in vitro culture and call for its utilization for regeneration of cryopreserved yam shoot tips, which is often impeded by oxidation phenomena.展开更多
A French programme, “Réseau de mesure de la qualité des sols: biodiversité des organismes” (RMQS BioDiv) was developed in Brittany (27,000 km2 in the western part of France) as an initial assessment o...A French programme, “Réseau de mesure de la qualité des sols: biodiversité des organismes” (RMQS BioDiv) was developed in Brittany (27,000 km2 in the western part of France) as an initial assessment of soil biodiversity on a regional scale in relation to land use and pedoclimatic parameters. The nematode community assemblages were compared among the land use categories. Crops were characterised by a high abundance of bacterial-feeders, particularly opportunistic bacterial-feeders belonging to Rhabditidae. Meadows presented a higher total abundance of nematodes than did crops (20.6 ind·g-1 dry soil vs. 13.1 ind·g-1 dry soil), and they were mainly linked to the great abundance of plant-parasitic nematodes, particularly Meloidogyne, but with a very high heterogeneity between sampled plots. The nematodes were most abundant in forests (23.7 ind·g-1 dry soil) and presented the most structured community (SI = 82.2 in forests vs. 58.6 and 55.5 in crops and meadows, respectively). Forests had also the higher fungal component (fungal-feeders and facultative plant-feeders belonging to the Tylenchidae) leading to a significant higher part of the fungal decomposition pathway in forests than in crops. The ability of different taxonomic levels of nematode identifica- tion to discriminate among different cropping systems (i.e., continuous cropping system, crop with meadow in the rota- tion, meadow with crop in the rotation and permanent meadow) was also tested. The family level (48 families identified in these samples) was more efficient than the other taxonomic levels (86 taxa, 17 functional guilds and 6 trophic groups): best statistical significant discrimination for time spent in identification. The relation between the nematode ecological indices, the abundance of nematode trophic groups and the crop management practices were studied. The effects of fertilization, ploughing frequency, use of pesticides and management systems on ecological indices, particu- larly on the Maturity Indices, were observed.展开更多
Various studies on the difference of distal femoral condyles between genders have been reported recently in order to provide anatomic information for knee prosthesis design and surgical planning in total knee arthropl...Various studies on the difference of distal femoral condyles between genders have been reported recently in order to provide anatomic information for knee prosthesis design and surgical planning in total knee arthroplasty. They also had the objective to be used as a sex recognition character, as may be needed in forensic medicine. Except for a recent 3D approach on the distal femur, most of the studies used dimensional information or aspect ratio but not shape. Our 2D study aimed to determine the size and shape variation of femoral condyles in Thais, considering age, sex and sides. One hundred and twenty-four cadaveric femurs （male 84 legs and female 40 legs） were dissected. The specimens were photographed by digital camera and images were analyzed using three geometric techniques： （i） the landmark-based method （5 landmarks）, （ii） with or without addition of 23 sliding semilandmark and （iii） the outline-based methods. From the resulting geometric coordinates, size and shape were extracted for comparisons between genders and sides. Between sides, directional asymmetry could be detected only for shape variation, and only when introducing curves in the analyses （either through the semilandmarks technique or through the outline-based one）. Non-directional asymmetry, probably fluctuating asymmetry, was detected for size, as well as for shape, in both genders. Sex discrimination was performed for each geometric technique using two classification methods： the Mahalanobis distance classification and the Maximum likelihood classification. The latter provided much more satisfactory gender validated reclassification （87%） than shape （72%）.展开更多
<i>Khaya senegalensis</i><span><span><span style="font-family:;" "=""><span style="font-family:Verdana;"> is one of the largest and most majestic ...<i>Khaya senegalensis</i><span><span><span style="font-family:;" "=""><span style="font-family:Verdana;"> is one of the largest and most majestic trees in Africa. Overexploited for its precious wood and medicinal values, the natural stands of this species are in danger of extinction in Cote d’Ivoire. Its sustainable management through regeneration techniques and assessment of its degree of adaptation to the changing climate is necessary. </span><span style="font-family:Verdana;">The aim of this study is</span><span style="font-family:Verdana;"> to evaluate the effect of different environments on seedling germination and development in </span><span style="font-family:Verdana;"><i>Khaya senegalensis</i></span><span style="font-family:Verdana;">. A total of 2160 seeds from different mother plants and 540 individuals from seed germination were selected and evaluated. The trials were conducted on three sites that were distinct by their microclimate (two nurseries in Cote d’Ivoire and one greenhouse in France). Analysis of variance showed that germination and morphology parameters were not influenced by the characteristics of the mother plants used (p > 0.05), but rather by the study sites (P < 0.05). The stable and controlled greenhouse climate was more advantageous for latency time (12.66 ± 0.80 days), germination delay (16.96 96 ± 0.54 days), germination speed (19.66 ± 2.95 days), germination duration (10.83 ± 2.27 days) and germination rate (88.88 ± 7.97) with more vigorous sowing than the other two sites. The results showed in general that the higher the height of the seedlings, the thicker the diameter of the seedlings (r = 0.796) and the higher the number of leaves (r = 0.946). This savannah species is native to the arid zones of Africa, but this study highlighted its adaptive potential to changing and different climates. These results are decision support tools for the regeneration of native pioneer forest species with high agroforestry potential and socio-economic importance such as </span><span style="font-family:Verdana;"><i>Khaya senegalensis</i></span><span style="font-family:Verdana;">. This study could be extended to other species </span><span style="font-family:Verdana;">in order to</span><span style="font-family:Verdana;"> restore disturbed ecosystems.</span></span></span></span>展开更多
Many publications describe cryopreservation techniques but only a few studies have focused on the biochemical and physiological changes occurring in plants regenerated from seeds exposed to liquid nitrogen. This paper...Many publications describe cryopreservation techniques but only a few studies have focused on the biochemical and physiological changes occurring in plants regenerated from seeds exposed to liquid nitrogen. This paper aims at describing the effect of common bean seed cryostorage on mineral nutrition of young plantlets. The following elements were measured on leaves of 10-day-old plantlets from non-cryopreserved and cryopreserved seeds: Al, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, S, Se, Sr and Zn. At 10 days after sowing, both treatments (control and cryopreserved seeds) showed 100% seed germination without any visual phenotypic difference. However, contents of several elements in the leaves were different. Exposure of seeds to liquid nitrogen decreased Cu, Cd and Na uptake and increased absorption of B and Al. Further studies are required to understand the mechanisms underlying the relationship between seed exposure to liquid nitrogen and mineral nutrition during the early stages of plantlet growth.展开更多
基金The National Key R&D Program of China under contract No.2022YFB3903003-2the Shaanxi Key Research and Development Program under contract No.2022ZDLSF06-09.
文摘To refine the assumption that the contrast threshold of the human eye(Crt)remains constant in general visibility theory,we integrated an artificial intelligence-based approach with a mechanistic model(AI-SD)to derive the equivalent contrast threshold at 488 nm(C_(488))from remote sensing reflectance on a pixel-by-pixel basis.The derived C_(488) was then applied to estimate Secchi depth(Z_(sd)).We trained and validated the AI-SD model using an extensive fieldmeasured dataset(N=1577)encompassing oceanic,coastal,and inland waters and compared its performance with a traditional mechanistic model.Our findings indicate that C_(488) theoretically ranges from 1.85×10^(−5) sr^(−1) to 0.138 sr^(−1) and improves the accuracy of Z_(sd) estimates from field-measured or satellite-derived remote sensing reflectance(R_(rs))by over 10%compared to the traditional model.Furthermore,applying the AI-SD model to global R_(rs) data revealed that C_(488) exhibits spatial and temporal variability across the world’s oceans.We linked this variability to the observed,yet traditionally unexplained,non-monotonic relationship between Z_(sd) and solar zenith angle-related water-leaving radiance.These results highlight the potential for enhancing global water transparency monitoring via ocean color satellites by incorporating accurate,pixel-level C_(488) values.
文摘At peak granulite-facies metamorphic conditions, lower continental crust is arguably fluxed by large amounts of two key low water activity fluids： （i） high-density CO2 and/or （ii） concentrated saline so- lutions. These fluids are either internally-derived, generated by mineral reactions or dehydration melting or, notably for CO2, externally-derived, issued from the underlying mantle. Postmetamorphic evolution results in complete disappearance of these fluids, except for minute remnants preserved in minerals as fluid inclusions. Two major processes are involved： （i） at peak conditions, granitoid magmas form, migrate upward, and crystallize as shallow intrusions in the upper crust （mineralized porphyry types or reduced intrusions）; （ii） during the rapid decompression which almost systematically follows a period of post-peak isobaric cooling, especially for ultrahigh-temperature granulites （anticlockwise P-T paths）, quartz-carbonate megashear zones are formed by repeated periods of seismic activity. Seismic activity may continue until all free fluids have disappeared, resulting in the ultramylonites and pseudotachylites that are found in many granulite domes. A great majority of vein-type Au deposits worldwide occur in the above-mentioned settings or nearby. We suggest that the Au has been scavenged by the granulite fluids, then redistributed and concentrated during the formation of veins and related phenomena.
文摘The formation of continents involves a combination of magmatic and metamorphic processes. These processes become indistinguishable at the crust-mantle interface, where the pressure-temperature（P-T）conditions of（ultra） high-temperature granulites and magmatic rocks are similar. Continents grow laterally, by magmatic activity above oceanic subduction zones（high-pressure metamorphic setting）, and vertically by accumulation of mantle-derived magmas at the base of the crust（high-temperature metamorphic setting）. Both events are separated from each other in time; the vertical accretion postdating lateral growth by several tens of millions of years. Fluid inclusion data indicate that during the high-temperature metamorphic episode the granulite lower crust is invaded by large amounts of low H2O-activity fluids including high-density CO2 and concentrated saline solutions（brines）. These fluids are expelled from the lower crust to higher crustal levels at the end of the high-grade metamorphic event. The final amalgamation of supercontinents corresponds to episodes of ultra-high temperature metamorphism involving large-scale accumulation of these low-water activity fluids in the lower crust.This accumulation causes tectonic instability, which together with the heat input from the subcontinental lithospheric mantle, leads to the disruption of supercontinents. Thus, the fragmentation of a supercontinent is already programmed at the time of its amalgamation.
文摘Recalling some of the most important events and persons during his education and career, the author sketches his growth from a young engineer, educated in the sanctuary of solid state reactions, to an involved fully devoted scientific career for the study of fluids in the deep Earth. Most important in this respect was the discovery of C02 inclusions in granulites, which triggered years of discussion on fluid- absent or fluid-assisted granulite metamorphism. To some extent, this debate is a continuation of the former granite controversy, but it shows also how the famous battle of ＂soaks against pontiffs＂ could have been easily avoided.
文摘Fluid （and melt） inclusion studies have shown a marked devel- opment in the last decades, as indicated by the increasing number of papers and as covered under major themes in specialized meetings （e.g. ECROFI in Europe, PACROFI in America, ACROFI in Asia）. However, a basic text book is lacking in current literature, available information being either somewhat outdated （e,g. Roedder, 1984） or scattered in multi-author ＂short course＂, mainly organized by the Mineralogical Societies of Canada, America or Europe. A result is that basic features of fluid inclusion studies, notably its key technique, microthermometry, and recently supplemented by micro Raman of infrared spectroscopy, is rarely taught in most universities, leaving the student alone to discover a field of study which has grown to the dimensions of a major science.
文摘Interpretation of primary growth markers (modules) is neglected in sustainable resource management processes, yet it opens up prospects for long time series on tree crown development, necessary for their characterization in the current context of climate change. This study aimed to assess the morphological variation of crown shoots in <i><span style="font-family:Verdana;">Parkia biglobosa</span></i><span style="font-family:Verdana;"> in the face of a changing environment. Axis growth modules of 420 individuals of different ages were retrospectively analyzed in the presence or absence of shading during the wet and dry seasons in seven localities in Cote d’Ivoire. The results showed that the developmental environment of individuals did not influence the growth modules dimensions (P > 0.05). However, module size remained significantly different between locations (P < 0.05). The southern part of the gradient is still favourable and has priority for the establishment of permanent plots. The modules morphology differs from the youngest to the oldest individuals (P < 0.05). The rainy season remains the ideal period for the implementation of agroforestry reforestation programmes based on this species (P < 0.05). </span><i><span style="font-family:Verdana;">Parkia biglobosa</span></i><span style="font-family:Verdana;"> is a monochasial sympod (Pseudo-monopod) with a relay axis that follows the Paul Champagnat architectural model in the young stage, and transits to the Wilhelm Troll model later in the adult and old stage. This information contributes to the understanding of the functioning of crown and the adaptation of this species to a varying environment. It could guide choice of suitable environment and ideal genotype for the implementation of a reforestation or agroforestry programme based on </span><i><span style="font-family:Verdana;">Parkia biglobosa</span></i><span style="font-family:Verdana;">.</span>
文摘The rapid rate of deforestation in Cote d’Ivoire has led to loss of plant species diversity and also threatens some commercial tree species with extinction.Some reforestation and aff orestation has been completed.However,for some species,the numbers of surviving transplants has declined.Hence,it is necessary to develop properly adapted and resilient genotypes that can eff ectively support the programs of forest restoration.In this context we evaluated the eff ects of the provenances of seeds and of various treatments on the germination rates and on plant growth of four commercial trees species(Pycnanthus angolensis,Terminalia superba,Mansonia altissima and Pterygota macrocarpa).We analyzed these parameters for seeds of three provenances(Daloa,Akoupéand Daoukro)of four species and for thirty plants aged 6 months per provenance.Time to begin germination and time to reach maximum germination were similar among species,and were not infl uenced by either treatment or provenance.Untreated seeds and those soaked for 24 and 48 h in water at room temperature yielded the highest germination rates,irrespective of species or provenance.The one exception was P.angolensis,for which no germination was recorded.Within species,some provenances produced higher germination percentages than did others.No clear relationship was computed between the germination rate and the morphometric characteristics of the seeds which varied signifi cantly between provenances.Plant growth and morphological variability also depended greatly on provenance.Genetic factors might be implicated,therefore provenance trials should be undertaken and evaluated.Furthermore,molecular analysis should be undertaken to confi rm the implications of genetic factors and allow for genetic selection.
基金DDvR would like to thank the NRF(Grant No. IFR1202190048)the University of Johannesburg for financial support
文摘Fluid infiltration into retrograde granulites of the Southern Marginal Zone （Limpopo high grade terrain） is exemplified by hydration reactions, shear zone hosted metasomatism, and lode gold mineralisation. Hydration reactions include the breakdown of cordierite and orthopyroxene to gedrite ＋ kyanite, and anthophyllite, respectively. Metamorphic petrology, fluid inclusions, and field data indicate that a low H2O-activity carbon-saturated CO2-rich and a saline aqueous fluid infiltrated the Southern Marginal Zone during exhumation. The formation of anthophyllite after orthopyroxene established a regional retrograde anthophyllite-in isograd and occurred at P-Tconditions of -6 kbar and 610 ℃, which fixes the minimum mole fraction of H20 in the CO2-rich fluid phase at ~ 0.1. The maximum H20 mole fraction is fixed by the lower temperature limit （~800 ℃） for partial melting at -0.3. C-O-H fluid calculations show that the CO2-rich fluid had an oxygen fugacity that was 0.6 log10 units higher than that of the fayalite-magnetite- quartz buffer and that the CO2/（CO2＋CH4） mole ratio of this fluid was 1. The presence of dominantly relatively low density CO2-rich fluid inclusions in the hydrated granulites indicates that the fluid pressure was less than the lithostatic pressure. This can be explained by strike slip faulting and/or an increase of the rock permeability caused by hydration reactions.
文摘Soil microbial biomass carbon (MBC), β-glucosidase, acid phosphatase and fluorescein diacetate (FDA) activities and bacterial community structure were assessed in a long-term (26 years) experiment, at physiological stages of sorghum growth, comparing different management methods for organic (manure, straw residues) and inorganic (urea) amendments at the INERA field station in Saria (Burkina Faso). Annual application of manure led to the highest soil microbial biomass and enzyme activities. Investigations indicated that only microbial biomass and β-glucosidase activities were affected during the cropping season. Phosphatase and FDA enzyme activities did not depend on the crop development stages. The application of N fertilizer modified phosphatase and FDA enzyme activities, the activities being higher in soils amended with N fertilizer. The bacterial community structure was analyzed by PCR-denaturing gradient gel electrophoresis (PCR-DGGE) targeting the eubacterial 16S rRNA gene. Cluster analysis of PCR-DGGE patterns showed two major clusters, the first containing the mineral fertilization and straw treatments and the second, the straw + urea, manure and manure + urea treatments. Sorghum grain yields were the highest for manure treatments. In this long-term experiment, applying straw did not produce a better grain yield than that obtained in the un-amended plot.
文摘The aim of this study was to test the impact of Rhizophagus irregularis, an arbuscular mycorrhizal fungus (AMF), on durum wheat growth and soil microbial functionalities in a field inoculation trial conducted in Morocco. The results showed that i) the R. irregularis inoculum effectively improved wheat growth, ii) wheat growth promotion depended on the soil mycorrhizal infectivity and iii) functional abilities of soil microflora depended on AMF inoculation. This study confirms that field AMF inoculation can be proposed as an effective agronomic practice in wheat production and as a sustainable cultural practice to manage soil biofunctioning. To fully promote inoculation practices, a better knowledge of AMF ecology has to be acquired to better adapt AMF inoculation to environmental conditions, and thus warrant better yields and agricultural sustainability.
文摘This study presents the ore texture, mineralogy and whole rock geochemistry of iron occurrence from the Edea North area located at the upper limit of the Nyong Unit, part of the Congo craton. This iron mineralization is of magnetite quartzite type enclosed by metamorphic rocks of the granulite facies. Two main facies have been identified over the study area including the banded and the massive facies. The mineralogical set of these facies is in majority represented by magnetite, quartz and pyroxene martite in addition to minor biotite, apatite, and amphibole. Magnetite presents as irregular and elongated minerals which can contain quartz inclusions of various shapes and sizes, as blasts clustering, around pyroxenes and isolated xenomorphic magnetite minerals in the silicate phases. Quartz varies from fine to coarse-grained and ribbon quartz. This indicates re-crystallization and deformation during metamorphism. Electron microprobe analysis on magnetite and martite show Fe2O3 contents that vary between 96.11 and 99.76. Whole rock chemical data showed that Fe-contents are as high as 62.9 wt%. The SiO2 content varies between 33.8 wt% and 51.2 wt%. Iron oxides and SiO2 are negatively correlated. Moreover, the low positive correlations between Al2O3 and HFSE, and LILE suggest a contribution of clastic materials in the protolith of studied materials. The samples show low contents of V, Cr, Ba, Zr with respect to igneous rocks. This may infer a sedimentary origin for the studied rocks;furthermore, these materials may have undergone hydrothermal alteration. The REE patterns reveal enrichment in LREE compared to HREE. Some samples show positive Eu (1.82) and other negative anomalies Eu (0.54 to 0.97). The lack of Ce anomalies suggests that the depositional environment of the Edea North iron occurrence was anoxic or suboxic. Overall, the Edea North iron occurrence may have undergone significant input from hydrothermal sources with imprints of the clastic during its deposition.
基金financed by the Chaires Merieux foundation(Paris,France)Pontifical Catholic University of Ecuador(M 13480)
文摘To distinguish species or populations using morphometric data is generally processed through multivariate analyses, in particular the discriminant analysis. We explored another approach based on the maximum likelihood method. Simple statistics based on the assumption of normal distribution at a single variable allows to compute the chance of observing a particular data （or sample） in a given reference group. When data are described by more than one variable, the maximum likelihood （MLi） approach allows to combine these chances to find the best fit for the data. Such approach assumes independence between variables. The assumptions of normal distribution of variables and independence between them are frequently not met in morphometrics, but improvements may be obtained after some mathematical transformations. Provided there is strict anatomical correspondence of variables between unknown and reference data, the MLi classification produces consistent classification. We explored this approach using various input data, and compared validated classification scores with the ones obtained after the Mahalanobis distance-based classification. The simplicity of the method, its fast computation, performance and versatility, make it an interesting complement to other classification techniques.
文摘In this work we compared the effect of the growth regulator content of the culture medium on the growth of in vitro shoot tips of five yam accessions belonging to four yam species (one Dioscorea alata, one D. rotundata, one D. cayenensis and two D. trifida). Medium S contained 0.6 μM benzyl adenine, 1.07 μM naphthalene acetic acid and 0.23 μM gibberellic acid while medium EBR contained 0.23 μM gibberellic acid and 0.1 μM 24-epibrassinolide. After 2 months of culture, oxidation level was significantly reduced on medium EBR compared to medium S for four of the five accessions tested. By contrast, medium EBR did not have any positive effect on shoot length since length of shoots produced after 2 months of culture on medium S and EBR were similar, except with accession 3-45T, for which shoot length was shorter on medium S compared to medium EBR. These results underline the potential of 24-epibrassinolide to reduce oxidation phenomena during in vitro culture and call for its utilization for regeneration of cryopreserved yam shoot tips, which is often impeded by oxidation phenomena.
文摘A French programme, “Réseau de mesure de la qualité des sols: biodiversité des organismes” (RMQS BioDiv) was developed in Brittany (27,000 km2 in the western part of France) as an initial assessment of soil biodiversity on a regional scale in relation to land use and pedoclimatic parameters. The nematode community assemblages were compared among the land use categories. Crops were characterised by a high abundance of bacterial-feeders, particularly opportunistic bacterial-feeders belonging to Rhabditidae. Meadows presented a higher total abundance of nematodes than did crops (20.6 ind·g-1 dry soil vs. 13.1 ind·g-1 dry soil), and they were mainly linked to the great abundance of plant-parasitic nematodes, particularly Meloidogyne, but with a very high heterogeneity between sampled plots. The nematodes were most abundant in forests (23.7 ind·g-1 dry soil) and presented the most structured community (SI = 82.2 in forests vs. 58.6 and 55.5 in crops and meadows, respectively). Forests had also the higher fungal component (fungal-feeders and facultative plant-feeders belonging to the Tylenchidae) leading to a significant higher part of the fungal decomposition pathway in forests than in crops. The ability of different taxonomic levels of nematode identifica- tion to discriminate among different cropping systems (i.e., continuous cropping system, crop with meadow in the rota- tion, meadow with crop in the rotation and permanent meadow) was also tested. The family level (48 families identified in these samples) was more efficient than the other taxonomic levels (86 taxa, 17 functional guilds and 6 trophic groups): best statistical significant discrimination for time spent in identification. The relation between the nematode ecological indices, the abundance of nematode trophic groups and the crop management practices were studied. The effects of fertilization, ploughing frequency, use of pesticides and management systems on ecological indices, particu- larly on the Maturity Indices, were observed.
文摘Various studies on the difference of distal femoral condyles between genders have been reported recently in order to provide anatomic information for knee prosthesis design and surgical planning in total knee arthroplasty. They also had the objective to be used as a sex recognition character, as may be needed in forensic medicine. Except for a recent 3D approach on the distal femur, most of the studies used dimensional information or aspect ratio but not shape. Our 2D study aimed to determine the size and shape variation of femoral condyles in Thais, considering age, sex and sides. One hundred and twenty-four cadaveric femurs （male 84 legs and female 40 legs） were dissected. The specimens were photographed by digital camera and images were analyzed using three geometric techniques： （i） the landmark-based method （5 landmarks）, （ii） with or without addition of 23 sliding semilandmark and （iii） the outline-based methods. From the resulting geometric coordinates, size and shape were extracted for comparisons between genders and sides. Between sides, directional asymmetry could be detected only for shape variation, and only when introducing curves in the analyses （either through the semilandmarks technique or through the outline-based one）. Non-directional asymmetry, probably fluctuating asymmetry, was detected for size, as well as for shape, in both genders. Sex discrimination was performed for each geometric technique using two classification methods： the Mahalanobis distance classification and the Maximum likelihood classification. The latter provided much more satisfactory gender validated reclassification （87%） than shape （72%）.
文摘<i>Khaya senegalensis</i><span><span><span style="font-family:;" "=""><span style="font-family:Verdana;"> is one of the largest and most majestic trees in Africa. Overexploited for its precious wood and medicinal values, the natural stands of this species are in danger of extinction in Cote d’Ivoire. Its sustainable management through regeneration techniques and assessment of its degree of adaptation to the changing climate is necessary. </span><span style="font-family:Verdana;">The aim of this study is</span><span style="font-family:Verdana;"> to evaluate the effect of different environments on seedling germination and development in </span><span style="font-family:Verdana;"><i>Khaya senegalensis</i></span><span style="font-family:Verdana;">. A total of 2160 seeds from different mother plants and 540 individuals from seed germination were selected and evaluated. The trials were conducted on three sites that were distinct by their microclimate (two nurseries in Cote d’Ivoire and one greenhouse in France). Analysis of variance showed that germination and morphology parameters were not influenced by the characteristics of the mother plants used (p > 0.05), but rather by the study sites (P < 0.05). The stable and controlled greenhouse climate was more advantageous for latency time (12.66 ± 0.80 days), germination delay (16.96 96 ± 0.54 days), germination speed (19.66 ± 2.95 days), germination duration (10.83 ± 2.27 days) and germination rate (88.88 ± 7.97) with more vigorous sowing than the other two sites. The results showed in general that the higher the height of the seedlings, the thicker the diameter of the seedlings (r = 0.796) and the higher the number of leaves (r = 0.946). This savannah species is native to the arid zones of Africa, but this study highlighted its adaptive potential to changing and different climates. These results are decision support tools for the regeneration of native pioneer forest species with high agroforestry potential and socio-economic importance such as </span><span style="font-family:Verdana;"><i>Khaya senegalensis</i></span><span style="font-family:Verdana;">. This study could be extended to other species </span><span style="font-family:Verdana;">in order to</span><span style="font-family:Verdana;"> restore disturbed ecosystems.</span></span></span></span>
文摘Many publications describe cryopreservation techniques but only a few studies have focused on the biochemical and physiological changes occurring in plants regenerated from seeds exposed to liquid nitrogen. This paper aims at describing the effect of common bean seed cryostorage on mineral nutrition of young plantlets. The following elements were measured on leaves of 10-day-old plantlets from non-cryopreserved and cryopreserved seeds: Al, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, S, Se, Sr and Zn. At 10 days after sowing, both treatments (control and cryopreserved seeds) showed 100% seed germination without any visual phenotypic difference. However, contents of several elements in the leaves were different. Exposure of seeds to liquid nitrogen decreased Cu, Cd and Na uptake and increased absorption of B and Al. Further studies are required to understand the mechanisms underlying the relationship between seed exposure to liquid nitrogen and mineral nutrition during the early stages of plantlet growth.
