检索结果-南通市图书馆

Empirical formulae to describe some physical properties of small groups of protogalaxies with multiplicity

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2021年第8期21卷 141-158页

作者： guillermo Arreaga-Garcia Departamento de Investigacion en Fisica Universidad de Sonora Apdo.Postal 14740C.P.83000HermosilloSonoraMexico

By means of identical cubic elements,we generate a partition of a volume in which a particle-based cosmological simulation is carried *** each cubic element,we determine the gas particles with a normalized density greater than an arbitrarily chosen density *** using a proximity parameter,we calculate the neighboring cubic elements and generate a list of *** imposing dynamic conditions on the gas particles,we identify gas clumps and their neighbors,so that we calculate and fit some properties of the groups so identified,including the mass,size and velocity dispersion,in terms of their multiplicity(here defined simply as the number of member galaxies).Finally,we report the value of the ratio of kinetic energy to gravitational energy of such dense gas clumps,which will be useful as initial conditions in simulations of gravitational collapse of gas clouds and clusters of gas clouds.

关键词： galaxies:kinematics and dynamics hydrodynamics methods:numerical

Macrobioerosion and Microbioerosion in Marine Molluscan Shells from Holocene and Modern Beaches (39°-40°S, South of Buenos Aires province, Argentina)

在线全文

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 2017年第4期91卷 1215-1230页

作者： Melisa p. CHARO Jose L. CAVALLOTTO guillermo ACENOLAZA Instituto Superior de Correlacion Geologica (INSUGEO/CONICET-UNT) Miguel Lillo 205 4000 Tucuman Argentina Servicio de Hidrografia Naval Av. Montes de Oca 2124 C1270ABWBuenos Aires Argentina

The marine sediments of the area of Verde peninsula - Jabali Island （39°28＇S/62°19%V-40°28＇ S/62°11＇W） Holocene in age （3-2 ky）, and modern beaches contain a significant amount of bioeroded mollusc shells. Fifteen sites were analyzed, in which 20.11% of the mollusc shells （2168 valves） presented bioerosion traces, in 54 species （30 bivalves and 24 gastropods）. Fourteen ichnogenera were reported： Entobia, Maeandropolydora, Iramena, Caulostrepsis, pennatichnus, pinaceocladichnus, Trypanites, and Gastrochaenolites （Domichnia）, Gnathichnus and Radulichnus （pascichnia）, Finichnus and Centrichnus （Fixichnia）, Oichnus （praedicnia）（macrobioerosion）, y Semidendrina （microbioerosion）, the latter is first reported in mollusc shells in Argentina. Eleven ichnospecies were identified Finichnus peristroma, Maeandropolydora sulcans, Gnathichnus pentax, pinaceocladichnus onubensis, Caulostrepsis taeniola, Centrichnus eccentricus, Radulichnus inopinatus, Oichnus simplex, Oichnus paraboloides, Oichnus gradatus, and Gastrochaenolites torpedo （lithic remains）. The dominant ichnogenera in the Holocene deposits are Iramena, Entobia and Oichnus. The same ichnogenera are constant with different abundance in the modern beaches, and increasing representation of pinaceocladichnus and pennatichnus. The dominant ichnofacies in the Holocene deposits is Trypanites, revealing a benthonic marine community composed of cheilostome bryzoans, clionaid sponges, predator gastropods, regular echinoids, polychaete annelids, bivalves, thallophytas and fungi. Generally, the area was described as a sublittoral, low-energy, stable environment with high rate of oxygenation, and sandy bottoms, with rocky bottoms at Villalonga locality.

关键词： molluscan bioerosion Holocene south of Buenos Aires province

A thick-disk galaxy model and simulations of equal-mass galaxy pair collisions

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2020年第11期20卷 333-353页

作者： guillermo Arreaga-Garcıa Departamento de Investigacion en Fsica Universidad de Sonora.Apdo.Postal 14740C.P.83000HermosilloSonoraMexico

We implement a numerical model reported in the literature to simulate the evolution of a galaxy composed of four matter components,such as:a dark-matter halo;a rotating disk of stars;a spherical bulge of stars and a ring of molecular *** show that the evolution of this galaxy model is stable at least for 10 Gyr(Gyr=109 years).We characterize the resulting configuration of this galaxy model by figures of the circular velocity and angular momentum distribution;the tangential and radial components of the velocity;the peak density evolution and the radial density ***,we calculate several models of equal-mass galaxy binary collisions,such as:(i)frontal and(ii)oblique(with an impact parameter),(iii)two models with initial conditions taken from a 2-body orbit and(iv)a very close *** allow comparison with the galaxy model,we characterize the dynamics of the collision models in an analogous ***,we determine the de Vaucouleurs fitting curves of the radial density profile,on a radial scale of 0–100 kpc,for all the collision models irrespective of the pre-collision *** study the radial mass density and radial surface density profiles at a smaller radial scale,0–20 kpc,we use a four-parameter fitting curve.

关键词： galaxies kinematics and dynamics galaxies interaction methods numerical

Over 9% efficiency achieved for all-polymer solar cells processed by a green solvent

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2017年第8期60卷 1109-1110页

作者： guillermo C.Bazan Departments of Chemistry ＆ Biochemistry and Materials University of California Santa Barbara CA 93106 USA

Bulk-heterojunction polymer solar cells （pSCs） have at- tracted considerable attention owning to their potential for fabricating flexible, light-weight and large area solar cell panels via high-throughput roll-to-roll technologies. Compared with conventional pSCs comprising small mol- ecule acceptors, such as fullerenes, all-polymer solar cells （all-pSCs） containing blends of p-type/n-type polymers in the photoactive layer provide advantages including easily tunable absorption band, enhanced absorption coefficient,

关键词： pSCs on in is for efficiency achieved for all-polymer solar cells processed by a green solvent Over 9 by

Using Cartesian Slice plots of a Cosmological Simulation as Input of a Convolutional Neural Network

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2024年第11期24卷 225-242页

作者： guillermo Arreaga-García Departamento de Investigación en Física Universidad de Sonora.Apdo.Postal 14740C.P.83000HermosilloSonoraMexico

Using a uniform partitioning of cubic cells,we cover the total volume of aΛCDM cosmological simulation based on *** define a visualization cell as a spatial extension of the cubic cell,so that we collect all simulation particles contained in this visualization cell to create a series of Cartesian plots in which the overdensity of matter is clearly *** then use these plots as input to a convolutional neural network(CNN)based on the Keras library and TensorFlow for image *** assign a class to each plot,we approximate the Hessian of the gravitational potential in the center of the cubic *** selected cubic cell is then assigned a label of 1,2 or 3,depending on the number of positive eigenvalues obtained for the Householder reduction of the Hessian *** apply the CNN to several models,including two models with different visualization volumes,one with a cell size of type L(large)and the other with a cell type S(small).A third model combines the plots of the previous L and S cell *** far,we have mainly considered a slice parallel to the XY plane to make the *** last model is considered based on visualizations of cells that also include slices parallel to the ZX and ZY *** find that the accuracy in classification plots is acceptable,and the ability of the models to predict the class works *** results allow us to demonstrate the aim of this paper,namely that the usual Cartesian plots contain enough information to identify the observed structures of the cosmic web.

关键词： methods numerical cosmology theory (cosmology:)large scale structure of universe

Nestling sex ratio is unaffected by individual and population traits in the griffon vulture

在线全文

学校读者我要写书评

暂无评论

Current Zoology 2023年第3期69卷 227-235页

作者： guillermo Gomez-Lopez Felix Martinez Ana Sanz-Aguilar Martina Carrete guillermo Blanco Department of Evolutionary Ecology National Museum of Natural Sciences(MNCN)Spanish National Research Council(CSiC)Jose Gutierrez Abascal 228006 MadridSpain Escuela Internacional de Doctorado Universidad Rey Juan Carlos(URJC)Tulipan s/n28933 MostolesMadridSpain Animal Demography and Ecology Group Institut Mediterrani d'Estudis Avangats(IMEDEA)Miquel Marques 217020 EsporlesMallorcaSpain Applied Zoology and Conservation Group Universitat de les Illes Balears(UIB)Ctra.De Valldemossa km.7.507122PalmaSpain Department of physical Chemical and Natural SystemsUniversidad Pablo de Olavide(UPO)Ctra.de Utrera km.141013 SevillaSpain

Variation in offspring sex ratios is a central topic in animal demography and population *** studies have focused on bird species with marked sexual dimorphism and multiple-nestling broods,where the offspring sex ratio is often biased due to different individual or environmental ***,biases in offspring sex ratios have been far less investigated in monomorphic and single-egg laying species,and few studies have evaluated long-term and large-scale variations in the sex ratio of nestling ***,we explore individual and environmental factors potentially affecting the secondary sex ratio of the monomorphic griffon vulture Gyps *** used information collected at three breeding nuclei from central Spain over a 30-year period(1990–2020)to analyse the effects of nestling age,parental age,breeding phenology,conspecific density,population reproductive parameters,and spatial and temporal variability on nestling *** ratio did not differ from parity either at the population or the nuclei *** significant between-year differences were detected,even under highly changing conditions of food availability associated with the mad-cow *** found that tree nesting breeders tend to have more sons than daughters,but as this nesting behavior is rare and we consequently have a small sample size,this issue would require additional *** further research is needed to assess the potential effect of breeder identity on nestling sex ratio,this study contributes to understanding the basic ecology and population dynamics of Griffon Vultures,a long-lived species with deferred maturity and low fecundity,whose minor deviations in the offspring sex ratio might imply major changes at the population level.

关键词： offspring sex ratio nestling sex Gyps fulvus monomorphism mad-cow crisis demography

Approximate Expressions to Evaluate the performance in Butene-1 purification Units

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 1998年第3期6卷 87-92页

作者： Sergio p.Bressa Nestor O.Ardiaca Osvaldo M.Martinez guillermo F.Barreto Depto.de Ing.Qca. Fac.de Ing.U.N.L.P.l esq.47(1900)La PlataDepto.de Ing.Qca.Fac.de Ing.U.N.L.P.l esq.47(1900)La PlataDepto.de Ing.Qca.Fac.de Ing.U.N.L.P.l esq.47(1900)La PlataDepto.de Ing.Qca.Fac.de Ing.U.N.L.P.l esq.47(1900)La Plata

1 INTRODUCTIONSelective hydrogenatioll of small amounts of butynes and butadiene is industrially employedfor obtaining high purity butene-l used as co-monomer in the production of linear *** this purpose,the content o... 详细信息

关键词： selective hydrogenation butene-1 1 3-butadiene trickle bed reactor

Interspecific differences in plasma carotenoid profiles in nestlings of three sympatric vulture species

在线全文

学校读者我要写书评

暂无评论

Current Zoology 2023年第6期69卷 658-669页

作者： guillermo Blanco Damaso Hornero-Mendezb Department of Evolutionary Ecology Museo Nacional de Ciencias Naturales(CSIC)Jose Gutierrez Abascal 228006 MadridSpain Departament of Food phytochemistry Instituto de la Grasa(CSiC)Campus Universidad Pablo de Olavide41013 SevilleSpain

Carotenoids are diet-based micronutrients important in health and coloration *** species with similar diets can differ in the kinds and levels of circulating carotenoids,which suggests specific physiological mechanisms to efficiently utilize these micronutrients,regardless of their *** explored whether diet and parental provisioning of unusual sources of carotenoids(fresh vegetal matter and vertebrate feces)can explain the occurrence and concentrations of carotenoids in the cinereous vulture Aegypius monachus,griffon vulture Gyps fulvus,and Egyptian vulture Neophron percnopterus nestlings,even when these pigments appear to not be deposited in their integumentary system.A greater diversity of wild prey in diet could be behind the profile of higher concentrations of carotenoids in the Egyptian vulture,the species with carotenoid-dependent coloration during adulthood,while differences in diet composition between cinereous and griffon vultures do not translate to different carotenoid *** carotenoid profile appears to not be related to the ingestion of unusual matter rich in these compounds,although the infrequent occurrence of lycopene and unidentified y-carotene-like compounds suggest that these vultures may be exploiting vegetal matter that left no identifiable unconsumed remains in the nest of Egyptian *** consumption of green plant material by griffon vultures does not result in especially high levels of carotenoids when compared to the carotenoids found in cinereous vultures,which do not consume green plant *** feces were not provisioned to Egyptian vulture nestlings,despite the fact they contain carotenoids that adults need for appropriate ***,this study indicates that diet differences alone appear insufficient to explain contrasting *** carotenoid profiles,especially since all types of food consumed are considered to be poor in carotenoids,except vegetable *** suggest that n

关键词： avian scavengers carotenes coloration feeding habits micronutrients xanthophylls

Bioerosion on Late pleistocene Marine Mollusks:A paleoclimatological and paleoecological Comparison of MIS 7 and MIS 5e with Modern Beaches(Río Negro,Argentina)

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 2022年第4期96卷 1181-1198页

作者： Melisa p.CHARO Gisela D.CHARÓ guillermo ACEÑOLAZA Jose L.CAVALLOTTO Instituto Superior de Correlación Geológica(INSUGEO/CONICET-UNT)Miguel Lillo 205 4000 TucumánArgentina Laboratorio de Fluidodinámica Departamento de Ingeniería MecánicaFacultad de IngenieríaUniversidad de Buenos AiresPaseo Colón 850C1063ACVCiudad Autónoma de Buenos AiresArgentina Servicio de Hidrografía Naval Av.Montes de Oca 2124C1270ABW Buenos AiresArgentina

The Late pleistocene littoral ridges of southern South America,especially those of the north of Argentinean patagonia,contain remains of mollusk shells with bioerosion *** sites from marine isotope stages(2 from MIS 7,4 from MIS 5 e)and five sites from modern beaches from northern Río Negro province,with 40 taxa(17 bivalves and 23 gastropods)were analyzed,in the area between west of Baliza San Matías and Las Grutas(41°S).Three ichnogenera were identified in deposits of MIS 7:Entobia,Gastrochaenolites(Domichnia)and Oichnus(praedichnia)with one ichnospecies(***).Six ichnogenera were identified in deposits of MIS 5 e:Entobia,Meandropolydora,pinaceocladichnus,Iramena,Caulostrepsis and Oichnus with one ichnospecies(***).Seven ichnogenera were identified from modern beaches:Entobia,Meandropolydora,Iramena,Caulostrepsis,pinaceocladichnus,Gastrochaenolites(Domichnia)and Oichnus(praedicnia),with two ichnospecies(*** and ***).On this basis,it is inferred that pleistocene benthic communities were constituted from cheilostome bryzoans and polychaete annelids,together with drilling bivalves,predatory gastropods and overall warm-water species of *** these,Chama iudicai was found on plicatula gibbosa from MIS 7 and MIS 5 *** record of warm temperature species suggests a higher sea surface temperature(SST)than the present one and/or the influence of the warm southward Brazilian Current affecting the waters of Golfo San Matí*** the modern beaches surveyed,there is an increase in polychaete annelids,cheilostome bryzoans,temperate-cold species and drilling bivalves,as well as sandy substrate species,which together with an increase of Gastrochaenolites and Caulostrepsis,suggest a colder climate due to the greater influence of the Malvinas Current during the Holocene.

关键词： invertebrate paleontology ichnology Bivalvia Gastropoda polyplacophora bioerosion paleoclimatology paleoecology Quaternary/Holocene Argentina