Elettrogeosmosi a limite mobile     

Arnaldo Belluigi 《Pure and Applied Geophysics》1960,47(1):55-68

Riassunto Viene studiato l'andamento EGO quando all'anodo si crea uno strato isolante progrediente nel tempo:EGO a limite mobile. Dalla teoria discende una prassi operativa EGO atta a contenere lo strato tampone (elettricamente resistivo).

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Summary The electro-osmotic phenomenon (EGO) is studied with regard to an insulating layer which builds up at the anod (mobile-limit EGO). An efficient operative method may be to lower the input voltage by the same ratio as the ohmic resistance increases. Practically it may be sufficient to lower the input voltage by a fixed percentage now and then, i. e.; at the time the ohmic resistance increases, or some time before. The aim is to prevent the formation of «stopper resistances» in order bo get a suitable electric current flow i. e., keep low the ohmic resistance lowering continually the voltage.

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A missing piece from a bigger puzzle: declining occurrence of a transient group of bottlenose dolphins off Southeastern Brazil     

Liliane Lodi  Maurício Cantor  Fábio G. Daura‐Jorge  Cassiano Monteiro‐Neto 《Marine Ecology》2014,35(4):516-527

Bottlenose dolphins are widespread off South America with patchy distributions throughout coastal, nearshore and offshore waters. Only limited information on the connectivity between individuals from these different habitats exists, despite the importance of understanding the overall population structure. A group of bottlenose dolphins in an insular habitat off Brazil may help provide evidence of the structure of a larger pelagic population in Brazilian waters. It is unknown whether the dolphins that use this habitat seasonally are part of an open population, a closed population of transient animals, or even individuals from offshore or nearshore groups. To explore the nature of these seasonal visitors we combined two strategies. First, by assessing the population parameters, we described a small group of individuals (maximum of 38 individuals in 2004 and five individuals in 2010) characterized by wide‐ranging behavior, low survival probabilities (64%) and an apparent population decline. Secondly, by exploring their social organization at a fine scale, we observed that within a stable group, the dyadic associations are fluid and mostly of short duration, similar to well‐known coastal bottlenose dolphin societies. The evidence of a non‐structured social network seems to be coupled with apparent seasonal use of this insular protected area for calf rearing and/or reproductive strategies. Overall, our findings suggest that this group may not be an aggregation of individuals from different populations in a specific area, but a relatively stable group formed by the same animals. While continuing research efforts are necessary along the South America coast, the abandonment of the study area by this group may hamper the understanding of population structure and connectivity among pelagic and coastal populations of bottlenose dolphins, as well as the ecological and behavioral mechanisms driving their seasonal occurrence in oceanic habitats.  相似文献   

The Itaja�� foreland basin: a tectono-sedimentary record of the Ediacaran period, Southern Brazil     

M. A. S. Basei  C. O. Drukas  A. P. Nutman  K. Wemmer  L. Dunyi  P. R. Santos  C. R. Passarelli  M. C. Campos Neto  O. Siga Jr  L. Osako 《International Journal of Earth Sciences》2011,100(2-3):543-569

The Itajaí Basin located in the southern border of the Luís Alves Microplate is considered as a peripheral foreland basin related to the Dom Feliciano Belt. It presents an excellent record of the Ediacaran period, and its upper parts display the best Brazilian example of Precambrian turbiditic deposits. The basal succession of Itajaí Group is represented by sandstones and conglomerates (Baú Formation) deposited in alluvial and deltaic-fan systems. The marine upper sequences correspond to the Ribeir?o Carvalho (channelized and non-channelized proximal silty-argillaceous rhythmic turbidites), Ribeir?o Neisse (arkosic sandstones and siltites), and Ribeir?o do Bode (distal silty turbidites) formations. The Apiúna Formation felsic volcanic rocks crosscut the sedimentary succession. The Cambrian Subida leucosyenogranite represents the last felsic magmatic activity to affect the Itajaí Basin. The Brusque Group and the Florianópolis Batholith are proposed as source areas for the sediments of the upper sequence. For the lower continental units the source areas are the Santa Catarina, S?o Miguel and Camboriú complexes. The lack of any oceanic crust in the Itajaí Basin suggests that the marine units were deposited in a restricted, internal sea. The sedimentation started around 600?Ma and ended before 560?Ma as indicated by the emplacement of rhyolitic domes. The Itajaí Basin is temporally and tectonically correlated with the Camaqu? Basin in Rio Grande do Sul and the Arroyo del Soldado/Piriápolis Basin in Uruguay. It also has several tectono-sedimentary characteristics in common with the African-equivalent Nama Basin.  相似文献   

Relationship between sedimentation rates and benthic impact on Maërl beds derived from fish farming in the Mediterranean     

Sanz-Lázaro C  Belando MD  Marín-Guirao L  Navarrete-Mier F  Marín A 《Marine environmental research》2011,71(1):22-30

The aim of this work was to study the dispersion of particulate wastes derived from marine fish farming and correlate the data with the impact on the seabed. Carbon and nutrients were correlated with the physico-chemical parameters of the sediment and the benthic community structure. The sedimentation rates in the benthic system were 1.09, 0.09 and 0.13 g m?2 day?1 for particulate organic carbon (POC), particulate organic nitrogen (PON) and total phosphorus (TP), respectively. TP was a reliable parameter for establishing the spatial extent of the fish farm particulate wastes. Fish farming was seen to influence not only physico-chemical and biological parameters but also the functioning of the ecosystem from a trophic point of view, particularly affecting the grazers and the balance among the trophic groups. POC, PON and TP sedimentation dynamics reflected the physico-chemical status of the sediment along the distance gradient studied, while their impact on the benthic community extended further. Therefore, the level of fish farm impact on the benthic community might be underestimated if it is assessed by merely taking into account data obtained from waste dispersion rates. The benthic habitat beneath the fish farm, Ma?rl bed, was seen to be very sensitive to aquaculture impact compared with other unvegetated benthic habitats, with an estimated POC-carrying capacity to maintain current diversity of 0.087 g C m?2 day?1 (only 36% greater than the basal POC input). Environmental protection agencies should define different aquaculture waste load thresholds for different benthic communities affected by finfish farming, according to their particular degree of sensitivity, in order to maintain natural ecosystem functions.  相似文献   

Qualitative analysis of cosmological models in Brans-Dicke theory     

C. Romero  H. P. Oliveira  J. R. T. De Mello Neto 《Astrophysics and Space Science》1989,158(2):229-257

Isotropic and homogeneous cosmological models with a perfect fluid cource in Brans-Dicke theory are investigated from the point of view of dynamical system theory.Work partially supported by CNPq (Brazil).  相似文献   

Continuum hydrodynamics of dry granular flows employing multiplicative elastoplasticity     

Alomir H. Fávero Neto  Ronaldo I. Borja 《Acta Geotechnica》2018,13(5):1027-1040

We present a Lagrangian formulation for simulating the continuum hydrodynamics of dry granular flows based on multiplicative elastoplasticity theory for finite deformation calculations. The formulation is implemented within the smoothed particle hydrodynamics (SPH) method along with a variant of the usual dynamic boundary condition. Three benchmark simulations on dry sands are presented to validate the model: (a) a set of plane strain collapse tests, (b) a set of 3D collapse tests, and (c) a plane strain simulation of the impact force generated by granular flow on a rigid wall. Comparison with experimental results suggests that the formulation is sufficiently robust and accurate to model the continuum hydrodynamics of dry granular flows in a laboratory setting. Results of the simulations suggest the potential of the formulation for modeling more complex, field-scale scenarios characterized by more elaborate geometry and multi-physical processes. To the authors’ knowledge, this is the first time the multiplicative plasticity approach has been applied to granular flows in the context of the SPH method.  相似文献   

New method for estimating reference evapotranspiration and comparison with alternative methods in a fruit-producing hub in the semi-arid region of Brazil     

de Souza  Luciana Sandra Bastos  Silva  Maiara Tatiane Lima  Alba  Elisiane  de Moura  Magna Soelma Beserra  da Cruz Neto  José Francisco  de Souza  Carlos André Alves  da Silva  Thieres George Freire 《Theoretical and Applied Climatology》2022,149(1-2):593-602

Theoretical and Applied Climatology - Analysing alternative methods for estimating reference evapotranspiration (ET0) is essential for improving the management of water resources, especially where...  相似文献   

A multivariate analysis of Antarctic sea ice since 1979   总被引：1，自引：0，他引：1  

Newton de Magalh?es Neto  Heitor Evangelista  Kenny Tanizaki-Fonseca  Margareth Sim?es Penello Meirelles  Carlos Eiras Garcia 《Climate Dynamics》2012,38(5-6):1115-1128

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Unusual Carbonatite Lavas from Active Volcano, Oldoinyo Lengai     

?ngelo R. Silva Neto  Mércia J. D. Bezerra  Maria Cláudia S. Farias  Ródio Luis Brand?o Camara 《Journal of the Geological Society of India》2009,74(1):145

News and Notes

Unusual Carbonatite Lavas from Active Volcano, Oldoinyo Lengai  相似文献   

Instrumental and digital coronagraphy for the observation of the Uranus satellites’ upcoming mutual events     

M. Assafin  R.P. Campos  D.N. da Silva Neto  A.H. Andrei 《Planetary and Space Science》2008,56(14):1882-1887

Ground-based observations of faint satellites nearby their planets with 1-2 m class telescopes usually do not allow for high quality astrometry and photometry, due to saturation by the primary or to poor S/N ratio on the satellite images, generally embedded on the scattered light of the planet. Earth-based observations of the Uranus satellites’ upcoming mutual events in 2007-2008 are no exception. In most cases, the event will take place at 4 arcs or less from the planet, with “planet minus satellite” brightness differences of 10 magnitudes. So as to make feasible the observations of these important phenomena, we have developed a prototype of a coronagraph of simple design making use of good quality commercial optical systems. Pilot tests made with this coronagraph with a telescope of show that it is possible to obtain S/N ratios of 50 or higher for 10 s exposures, for satellites as close as 2 Uranus radii from the planet center. We have also developed numerical algorithms which perform digital coronagraphy in the images, with the elimination of the influence of the planets’ scattered light. This procedure considerably improves the S/N ratio of the satellite images (with or without a coronagraph instrument) and shall be applied in the reduction of the observations of the Uranus events so as to achieve the highest possible photometric and astrometric quality.  相似文献