Caracterização e classificação dos solos do Campo Experimental do Cerrado da Embrapa Amapá, Estado do Amapá.

bitstream/item/63154/1/Oriental-Doc43.pd

A Dynamic Model of Cascades on Random Networks with a Threshold Rule

Cascades on random networks are typically analyzed by assuming they map onto percolation processes and then are solved using generating function formulations. This approach assumes that the network is infinite and weakly connected, yet furthermore approximates a dynamic cascading process as a static percolation event. In this paper we propose a dynamic Markov model formulation that assumes a finite network with arbitrary average nodal degree. We apply it to the case where cascades follow a threshold rule, that is, that a node will change state ("flip") only if a fraction, exceeding a given threshold, of its neighbors has changed state previously. The corresponding state transition matrix, recalculated after each step, records the probability that a node of degree k has i flipped neighbors after j steps in the cascade's evolution. This theoretical model reproduces a number of behaviors observed in simulations but not yet reported in the literature. These include the ability to predict cascades in a domain previously predicted to forbid cascades without assuming that the network is locally tree-like, and, due to the dynamic nature of the model, a "near death" behavior in which cascades initially appear about to die but later explode. Cascades in the "no cascades" region require a sufficiently large seed of initially flipped nodes whose size scales with the size of the network or else the cascade will die out. Our theory also predicts the well known properties of cascades, for instance that a single node seed can start a global cascade in the appropriate regime regardless of the (finite) size of the network. The theory and simulations developed here are compared with a foundational paper by Watts which used generating function theory.Comment: Rev 1: Added citation to prior work by Gleeson and Cahalane. Revised abstract to sui

Mineralogical controls on mobility of rare earth elements in acid mine drainage environments

Supplementary data related to this article can be found at https://doi.org/10.1016/j.chemosphere.2018.04.095.Rare earth elements (REE) were analyzed in river waters, acid mine waters, and extracts of secondary precipitates collected in the Iberian Pyrite Belt. The obtained concentrations of the REE in river water and mine waters (acid mine drainage - AMD) were in the range of 0.57 μg/L (Lu) and 2579 μg/L (Ce), which is higher than previously reported in surface waters from the Iberian Pyrite Belt, but are comparable with previous findings from AMD worldwide. Total REE concentrations in river waters were ranged between 297 μg/L (Cobica River) and 7032 μg/L (Trimpancho River) with an average of 2468 μg/L. NASC (North American Shale Composite) normalized REE patterns for river and acid mine waters show clear convex curvatures in middle-REE (MREE) with respect to light- and heavy-REE. During the dissolution experiments of AMD-precipitates, heavy-REE and middle-REE generate the most enriched patterns in the solution. A small number of precipitates did not display MREE enrichment (an index Gdn/Lun < 1.0) in NASC normalized pattern and produced relatively lower REE concentrations in extracts. Additionally, very few samples, which mainly contained aluminum sulfates, e.g., pickeringite and alunogen, displayed light-REE enrichment relative to heavy-REE (HREE). In general, the highest retention of REE occurs in samples enriched in magnesium (epsomite or hexahydrite) and aluminum sulfates, mainly pickeringite.Financial support was provided by the Andalusian Autonomous Government Excellence Project, code P06-RNM-02167. This work was also co-funded by the European Union through the European Regional Development Fund, based on COMPETE 2020, project ICT (UID/GEO/04683/2013), reference POCI-01-0145-FEDER-007690, national funds provided by FCT. Post-Doctoral Fellowship through Erasmus Mundus SAT program and Young Scientist Research Grant (SEAS-2015−14) of the National University of Mongolia were supported for T.-O. Soyol-Erdene. The authors also appreciate the valuable comments and suggestions made by the anonymous reviewers

A country-wide probability sample of public attitudes toward stuttering in Portugal

Background: Negative public attitudes toward stuttering have been widely reported, although differences among countries and regions exist. Clear reasons for these differences remain obscure. Purpose: Published research is unavailable on public attitudes toward stuttering in Portugalas well as a representative sample that explores stuttering attitudes in an entire country. This study sought to (a) determine the feasibility of a country-wide probability samplingscheme to measure public stuttering attitudes in Portugal using a standard instrument (the Public Opinion Survey of Human Attributes–Stuttering [POSHA–S]) and (b) identify demographic variables that predict Portuguese attitudes. Methods: The POSHA–S was translated to European Portuguese through a five-step process. There after, a local administrative office-based, three-stage, cluster, probability sampling scheme was carried out to obtain 311 adult respondents who filled out the questionnaire. Results: The Portuguese population held stuttering attitudes that were generally within the average range of those observed from numerous previous POSHA–S samples. Demographicvariables that predicted more versus less positive stuttering attitudes were respondents’age, region of the country, years of school completed, working situation, and number of languages spoken. Non-predicting variables were respondents’ sex, marital status, and parental status. Conclusion: A local administrative office-based, probability sampling scheme generated a respondent profile similar to census data and indicated that Portuguese attitudes are generally typical

Mapeamento de solos das áreas de duas mesobacias hidrográficas no Nordeste paraense.

Este trabalho cumpre parte das necessidades de levantar e caracterizar os solos de duas áreas de mesobacias hidrográficas inseridas no projeto Gestabacias, previstas no diagnóstico do meio biofísico dessas áreas. O Projeto Gestabacias foi elaborado com o intuito de desenvolver uma rede de informações que permita integrar resultados de pesquisa sobre a integridade dos recursos solo, vegetação, água e fauna aquática em mesobacias hidrográficas relacionadas com diferentes sistemas de uso da terra praticados, como subsídio à construção de um modelo de gestão participativa dos recursos naturais nessas bacias. Ao ultrapassar os limites da academia e dos centros de pesquisa, prevê a socialização das informações disponíveis e a participação de diferentes atores envolvidos na elaboração de modelos de gestão dos recursos naturais em bacias hidrográficas localizadas no nordeste do Estado do Pará

Fiber reinforced concrete. Part II: Application

The present paper is the second part of two companion papers related with the design and application of fiber reinforced concrete (FRC) in structural elements. It is presented a case study regarding the use of FRC in the development and construction of a new sustainable building system based on the assembly of structural prefabricated sandwich panels formed by thin outer layers of steel fiber reinforced self-compacting concrete (SFRSCC) and an insulation core. The outer layers of SFRSCC are connected with innovative glass fiber reinforced polymer (GFRP) connectors. The structural concept is presented and the numerical and experimental work carried out for the construction of a real scale prototype is briefly describe

A multiscale model for optimizing the flexural capacity of FRC structural elements

In the present work, a multiscale model for fibre reinforced concrete (FRC) beams failing in bending is presented. At the microstructural level, the fibre is modelled as a one-dimensional continuum with axial, shear and bending deformability, with cohesive-like interfaces to simulate the interaction with the surrounding concrete. At the macroscopic level, the response of the beam is simulated by discretising the cross-section into layers and by enforcing the proper compatibility conditions between the layers. In the post-cracking stage, the tensile capacity is assured by the fracture energy of the concrete and the fibre resisting mechanisms simulated by the fibre pullout constitutive laws determined at the microstructural level. The model can account for fibre distribution and orientation, controlled by the casting conditions and geometry of the mould. By using experimental data available from the open literature, it is proved that such an integrated approach is able to derive, by inverse analysis, the stress-crack width relationship of FRC, which is the fracture mode I information in the material nonlinear analysis of FRC structures with approaches based on the finite element method.J.O.A. Barros, T. dos Santos Valente and I. G. Costa wish to acknowledge the support by FEDER through the Operational Program for Competitiveness Factors - COMPETE and Internationalization Program (POCI), under the project NG TPfib POCI-01-0247-FEDER-03371

Use of 2,4-D as a burndown treatment for soybeans in no-till cropping systems in the Cerrados region

O experimento foi conduzido em solo originalmente sob vegetação de Cerrado com textura leve. Utilizou-se para dessecação da cobertura vegetal, composta de plantas daninhas com predominância de Commelina benghalensis, o herbicida 2,4-D amina nas doses de 72, 144,216,288,432,576 e 720 g/ha, aplicadas em uma única vez. A semeadura da soja foi feita com um, dois, três, quatro, cinco, oito e dez dias após a dessecação. Os tratamentos foram constituídos pelas épocas de semeadura da soja após a aplicação do herbicida, combinadas com as doses do 2,4-D, no delineamento em blocos casualizados com três repetições. Avaliou-se a densidade e o crescimento das plantas de soja, através da medição da altura das plantas aos 45 dias após a semeadura e na pré-colheita, altura da inserção da primeira vagem, peso de grãos por planta e produtividade: Os resultados demonstraram que todas as variáveis analisadas foram influenciadas pelo herbicida quando aplicado de um até cinco dias antes da semeadura da soja. A produtividade, embora não tenha sido influenciada significativamente pelas épocas de semeadura, foi sensivelmente reduzida com o aumento das doses do herbicida. Mesmo em baixa concentração, o 2,4-D afetou o crescimento da soja nas seis épocas de semeadura após a aplicação. Desse modo, o uso do 2,4-D poderá ser recomendado para solos leves de Cerrados, nas aplicações de dessecação, até a dose de 720 g/ha, desde que aplicado com um intervalo mínimo de 8 dias antes da semeadura direta da soja.  A field experiment was carried out in the Cerrados region in Rondonõpolis, MT, Brazil, in order to evaluate the behavior of2,4-D amine, applied alone and as a pre-site preparation at 72, 144,216,288,432,576 and 720 grams per hectare, to control the weed spectrum in no-till soybean. Commelina benghalensis was the predominant weed species. Soybean was seeded at 1,2,3, 4,5,8 and 10 days after burndown treatment and the planting timing was crossed with 2,4-D rates, applied in a randomized block design in three replications. The crop response as measured by stand and plant height was evaluated at 45 days after spraying and as a pre-harvest evaluation at the first pod insertion. The number of pods per plant, dry weight and productivity were assessed. The results sbowed that ali the variables analyzed were affected by the herbicide when soybean was planted up to 5 days after spray treatment. Considering only the planting time, the productivity was not statisticaIly different, however it was significantly reduced when the rates of2,4-D were increased. Even at the lower rate, a plant growth reduction was observed. As conclusion, 2,4-D amine can be recommended as a burndown treatment for Cerrados sandy soil, up to 720 g/ha, since soybeans are planted at least 8 days after the herbicide application

Primate rhythmic categories analyzed on an individual basis

Rhythm is a fundamental feature characterizing communicative displays, and recent studies showed that primate songs encompass categorical rhythms falling on small integer ratios observed in humans. We individually assessed the presence and sexual dimorphism of rhythmic categories, analyzing songs emitted by 39 wild indris. Considering the intervals between the units given during each song, we extracted 13556 interval ratios and found three peaks (at around 0.33, 0.47, and 0.70). Two peaks indicated rhythmic categories corresponding to small integer ratios (1:1, 2:1). All individuals showed a peak at 0.70, and most showed those at 0.47 and 0.33. In addition, we found sex differences in the peak at 0.47 only, with males showing lower values than females. This work investigates the presence of individual rhythmic categories in a non-human species; further research may highlight the significance of rhythmicity and untie selective pressures that guided its evolution across species, including humans

Competition and Selection Among Conventions

In many domains, a latent competition among different conventions determines which one will come to dominate. One sees such effects in the success of community jargon, of competing frames in political rhetoric, or of terminology in technical contexts. These effects have become widespread in the online domain, where the data offers the potential to study competition among conventions at a fine-grained level. In analyzing the dynamics of conventions over time, however, even with detailed on-line data, one encounters two significant challenges. First, as conventions evolve, the underlying substance of their meaning tends to change as well; and such substantive changes confound investigations of social effects. Second, the selection of a convention takes place through the complex interactions of individuals within a community, and contention between the users of competing conventions plays a key role in the convention's evolution. Any analysis must take place in the presence of these two issues. In this work we study a setting in which we can cleanly track the competition among conventions. Our analysis is based on the spread of low-level authoring conventions in the eprint arXiv over 24 years: by tracking the spread of macros and other author-defined conventions, we are able to study conventions that vary even as the underlying meaning remains constant. We find that the interaction among co-authors over time plays a crucial role in the selection of them; the distinction between more and less experienced members of the community, and the distinction between conventions with visible versus invisible effects, are both central to the underlying processes. Through our analysis we make predictions at the population level about the ultimate success of different synonymous conventions over time--and at the individual level about the outcome of "fights" between people over convention choices.Comment: To appear in Proceedings of WWW 2017, data at https://github.com/CornellNLP/Macro