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PRECONDITIONED SPECTRAL PROJECTED GRADIENT METHOD ON CONVEX SETS

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Journal of Computational Mathematics 2005年第3期23卷 225-232页

作者： LenysBello MarcosRaydan dpto.deMatemdtica FacultaddeCiencias(FACYT)UniversidaddeCaraboboValenciaVenezuela dpto.deComputación UniversidadCentraldeVenezuelaAp.47002Caracas1041-AVenezuela

The spectral gradient method has proved to be effective for solving large-scale unconstrained optimization problems. It has been recently extended and combined with the projected gradient method for solving optimization problems on convex sets. This combination includes the use of nonmonotone line search techniques to preserve the fast local convergence. In this work we further extend the spectral choice of steplength to accept preconditioned directions when a good preconditioner is available. We present an algorithmthat combines the spectral projected gradient method with preconditioning strategies toincrease the local speed of convergence while keeping the global properties. We discuss implementation details for solving large-scale problems.

关键词： Spectral gradient method Projected gradient method Preconditioning tech-niques Nonmonotone line search

Seed bank dynamics of an invasive alien species, Helianthus annuus L.

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Journal of Plant Ecology 2020年第3期13卷 313-322页

作者： Alejandro Presotto Fernando Hernández Mauricio Casquero Roman Vercellino Claudio Pandolfo Mónica Poverene Miguel Cantamutto dpto.agronomía Universidad Nacional del Sur(UNS)San Andrés 8008000 Bahía BlancaArgentina CERZOS Universidad Nacional del Sur(UNS)-CONICETCamino La Carrindanga Km 78000 Bahía BlancaArgentina Corteva Agriscience.Integrated field Sciences RN N178 Km 112700 PergaminoArgentina Estación Experimental Agropecuaria Hilario Ascasubi Instituto Nacional de Tecnología Agropecuaria(INTA)RN N3 Km 7948142 Hilario AscasubiArgentina

Aims The ability to form persistent seed banks is one of the best predictors of species’potential to establish in new *** sunflower is native to North America where the formation of persistent seed banks is promoted by disturbance and it plays a key role on the establishment and persistence of native ***,the role of the seed banks on the establishment and persistence of invasive populations has not been ***,we evaluated the role of seed bank and disturbance on the establishment and fitness,and seed persistence in the soil in several sunflower biotypes collected in ruderal(wild Helianthus annuus)and agrestal(natural crop–wild hybrid)habitats of Argentina as well as volunteer populations(progeny of commercial cultivars).Methods In a seed-bank experiment,we evaluated emergence,survival to reproduction,survival of emerged seedlings,inflorescences per plant and per plot under disturbed and undisturbed conditions over 2 years;in a seed-burial experiment,we evaluated seed persistence in the soil over four springs(6,18,30 and 42 months).Important Findings Overall,seedling emergence was early in the growing season(during winter),and it was promoted by disturbance,especially in the first *** this,the number of inflorescences per plot was similar under both conditions,especially in *** the second year,emergence from the seed bank was much lower,but the survival rate was *** the seed-burial experiment,genetic differences were observed but seeds of ruderals and agrestals persisted up to 42 months while seeds of the volunteer did not persist longer than 6 *** agrestal biotype showed an intermediate behavior between ruderals and volunteers in both *** findings showed that wild and crop–wild sunflower can form persistent seed banks outside its native range and that disturbance may facilitate its establishment in new areas.

关键词： seed bank seed persistence wild sunflower invasive alien species ruderal agrestal

Ecosystem Services of Grazed Grasslands in the Flooding Pampa

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Phyton-International Journal of Experimental Botany 2024年第6期93卷 1179-1202页

作者： Elizabeth J.Jacobo Adriana M.Rodríguez Facultad de agronomía Área de AgroecologíaUniversidad de Buenos AiresBuenos Aires1417Argentina Facultad de agronomía Departamento de Producción AnimalUniversidad de Buenos AiresBuenos Aires1417Argentina

The Flooding Pampa grasslands are the last remnant of the Rio de la Plata grasslands in ***-genic interventions have led to severe degradation and,as a result,the ecosystem services provided by the grass-lands are declining,in terms of provisioning,regulating,and supporting *** synthesized the existing literature on the ecosystem goods and services provided by these grasslands under grazing in different conditions and conservation *** found that plant and animal diversity and primary production are the most studied ecosystem services,while climate regulation,water supply,nutrient cycling,meat production and erosion control,in that order,are less *** services are *** grazing and glyphosate spraying are the main drivers of grassland *** grazing and conservative stocking rates have been shown to reverse degradation and demonstrate that livestock production is compatible with ecosystem conserva-tion by maintaining regulating and provisioning *** these management strategies are poorly integrated,improving their implementation will require important changes in farmers’decisions and the development of policies that create the economic conditions for this to *** is needed to understand the conditions that prevent the knowledge generated from being transferred to producers and translated into practices that would improve the provision of ecosystem services.

关键词： Salado basin sustainability biodiversity rangelands meat production adaptative multi paddock grazing process technologies agroecology

Classification of Some Nilpotent Class of Leibniz Superalgebras

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Acta Mathematica Sinica,English Series 2010年第5期26卷 799-816页

作者： Luisa M.CAMACHO José R.GóMEZ Rosa M.NAVARRO Bakhrom A.OMIROV dpto. Matemática Aplicada I Universidad de Sevilla dpto. de Matemáticas Universidad de Extremadura Institute of Mathemátics and Information Technologues Uzbekistan Academy of Science

The aim of this work is to present the description of Leibniz superalgebras up to isomorphism with characteristic sequence （n｜m - 1, 1） and nilindex n ＋ m.

关键词： Lie superalgebras Leibniz superalgebras nilindex charasteristic sequence

Some Smoothness Results for Classical Problems in Optimal Design and Applications

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Chinese Annals of Mathematics,Series B 2015年第5期36卷 703-714页

作者： Juan CASADO-DIAZ dpto.de Ecuaciones Diferenciales y Analisis Numerico University of Seville41012 SevillaSpain

The author considers two classical problems in optimal design consisting in maximizing or minimizing the energy corresponding to the mixture of two isotropic materials or two-composite material. These results refer to... 详细信息

关键词： Optimal design Two-phase material Non-existence Relaxation

Early detection of tomato bacterial canker by reflectance indices

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Information Processing in Agriculture 2022年第2期9卷 184-194页

作者： Gabriela Cordon Carolina Andrade Lucia Barbara Ana Maria Romero Universidad de Buenos Aires Consejo Nacional de Investigaciones Cientı´ficas y Te´cnicasInstituto de Investigaciones Fisiolo´gicas y Ecolo´gicas Vinculadas a la Agricultura(IFEVA)Facultad de Agronomı´aBuenos AiresArgentina Universidad de Buenos Aires Facultad de Agronomı´aA´rea de Educacio´n AgropecuariaBuenos AiresArgentina Universidad de Buenos Aires Facultad de Agronomı´aCa´tedra de Fitopatologı´aBuenos AiresArgentina

Early detection of infected asymptomatic plants could prevent the dissemination of tomatobacterial canker throughout the crop and, thus, reduce associated economic losses. Reflectance spectroscopy has been proposed for the detection of diseases in plants, mainlycaused by foliar fungal pathogens. In contrast, bacterial canker is a vascular disease thatdoes not produce visible foliar symptoms until it is too late to avoid contagion to otherplants. The effects of the disease on the conductivity of the xylem have an impact onthe water content of the leaves;initially, a subtle effect that cannot be assessed with thenaked eye but can be evaluated by reflectance spectroscopy. The objective of this workwas to identify indices, based on the reflectance spectral signature of the plants, for thedetection of tomato plants affected by bacterial canker prior to the appearance of symptoms. To verify that the proposed methodology is applicable to a broad range of tomatogenotypes, two experiments were carried out with different tomato cultivars grown in potsand another on the ground in a greenhouse. Plants were inoculated with the pathogenicbacteria and the reflectance spectrum of the apical leaflet of two leaves per plant wereobtained before symptoms expression;several spectral indices were calculated from thereflectance spectra. Three indices, of the shortwave-infrared zone, allowed the detectionof bacterial canker inoculated plants in a fast and non-destructive way, up to one weekbefore symptoms were visible: Normalized Difference Water Index (NDWI), Simple Ratioof Water Index (SRWI) and Water Index 1 180 (WI1180). Our research demonstrates, forthe first time, the usefulness of spectral indices sensitive to water content for the identifi-cation of diseased plants. These indices arise as a promising tool for the early detection ofvascular plant diseases, that could be integrated into sustainable management plans.

关键词： Clavibacter michiganensis subsp. michiganensis Bacterial wilt Reflectance indices Solanum lycopersicum L

The Effect of Water and Salt Stress on Paspalum dilatatum,a Constituent of Pampas Natural Grasslands

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Phyton-International Journal of Experimental Botany 2024年第8期93卷 2009-2018页

作者： Claudia A.Porcelli Gerardo Rubio Flavio H.Gutiérrez Boem Raul S.Lavado Departamento de Química Facultad de AgronomíaUniversidad de Buenos AiresBuenos AiresC1417DSEArgentina Instituto de Investigaciones en Biociencias Agricolas y Ambientales(INBA) Facultad de AgronomíaUniversidad de Buenos AiresBuenos AiresC1417DSEArgentina

The effects of the salt stress on plant growth are usually increased by the water *** studied the impact of both stresses in simultaneous pulses of drought and salinity on Paspalum *** forage species is native to South America,spread in grasslands in many tropical,subtropical,and temperate areas of the world,and very common in grasslands of the Flooding Pampas of *** what happens in *** compared a pot experiment,a non-stressed control against water stress for a month(midpoint between field capacity and wilting point),and two saline stresses(moderate,6 d·Sm^(−1)and strong,12 d·Sm^(−1)),also for a *** biomass(green leaf;non-leaf green material,and dry material)and roots were harvested,weighed,and analyzed for nitrogen,phosphorus,and *** biomass of all components significantly decreased when both stresses were *** plus strong saline stress reduced by half the total biomasses,compared to the *** proportion of aerial biomass/root biomass ratio as well as aerial green component/dry materials ratio tend to decrease when subjected to both *** concentration in plants was not significantly affected,but phosphorus concentration increased in aerial biomass components,from 0.10 to 0.18 mg·kg^(−1)between the extreme treatments,but did not change in *** concentration in plants increased(i.e.,in green leave sodium(Na)increased from 0.27 to 2.01 mg·kg^(−1)between the extreme treatments),whereas other cations either did not change or decreased,affecting the ratios between *** performance allows us to infer that the Na accumulation of *** behaves in an intermediate range,compared to very tolerant to salts or non-salt tolerant species of the Paspalum *** agreement,when salts were applied in the form of a pulse,*** tolerated higher salinity than that found by other authors for the same species,using continuous salinity.

关键词： Dallis grass salinity drought sodium in plants phosphorus in plants potassium/sodium ratio

Morphometric Attributes of Two Native Forage Species According to Water Source Distance in Semiarid Central Grasslands of Argentina

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Phyton-International Journal of Experimental Botany 2024年第8期93卷 2063-2074页

作者： Carla Etel Suárez María Sol Rossini Ernesto Francisco Atilio Morici Héctor Daniel Esterlich Laboratorio de Ecología en Ambientes Semiáridos Ecología VegetalFacultad de AgronomíaUNLPamSanta Rosa6300Argentina Facultad de Ciencias Veterinarias UNLPamGeneral Pico6360Argentina Becaria Doctoral CONICET APNFacultad de AgronomíaUNLPamSanta Rosa6300Argentina

The semiarid grasslands of Argentina’s central region have been modified by domestic livestock grazing,both in their composition and *** increase in the proportion of woody and non-forage species and the decrease in forage species are some of the most evident results of this *** is limited available information about the effect of differential grazing pressures on morphometric attributes of native species,and it also depends on the life histories of the species in this *** objective of this work was to evaluate some morphometric aspects in the grasses Poa ligularis Nees ex Steud and Piptochaetium napostaense(Speg.).Hack according to distance from the water source in communities in the central semiarid region of *** study area included areas of low grassland,golden forests,and secondary forests in grasslands(6 fields with 9 paddocks).Grazing pressure was established based on the distance to the water source,so sampling areas were designated near the water source(grazing pressure is greater)and far from the water source(grazing pressure light)in each of the *** both species,specimens were selected at random,and the following attributes were measured:crown diameter at ground level(cm),burial depth(cm),average tiller weight per plant(***^(−1)),and the density of tillers per unit of crown surface(***^(−2)crown).The morphometric attributes evaluated showed differences according to the distance to the watering hole and in the different *** species presented similar behaviors for the *** were significant differences in the depth of burial and the average weight of tillers per plant,being greater in the areas close to the water *** the distance to the watering hole,there were no significant differences in crown diameter and tiller density,but the highest values were recorded for the former near the watering hole and for the second far from the watering *** pastures with low

关键词： Grazing pressure tiller density tiller weight crown burial depth Poa ligularis Piptochaetium napostaense

A Protocol for Fractal Studies on Porosity of Porous Media: High Quality Soil Porosity Images

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Journal of Earth Science 2017年第5期28卷 888-896页

作者： Carlos García-Gutiérrez Fernando San José Martínez J.Caniego dpto.Matemática Aplicada E.T.S.I.Navales Universidad Politécnica de Madrid dpto.Matemática Aplicada E.T.S.I.Agrónomos Universidad Politécnica de Madrid

A protocol for obtaining digital images from natural porous media with a wide range of pore sizes, intended for fractal studies of the porosity, is proposed. Soil porosity is used as para- digm of complex natural porous media in this study. The use of several imaging devices and fluores- cent compounds to enhance the contrast between the solid and the pore phase is tested. Finally a protocol is reached using a photo camera and a confocal microscope. It is the first time that confocal microscopy is used for this purpose. Artificial porous images are created through random Sierpinski carpet fractals and the statistical information of real soil images. These ground truth images are used in an objective comparison of automatic segmentation algorithms for the obtained images. A statistical classification on the performance of several automatic segmentation algorithms for this tv^e of images is reached.

关键词： porous media micromorphology image segmentation confocal microscope fractal,porosity photography.