4,151 research outputs found

    Implantação e manejo de vinhedos de base ecológica.

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    Some boundary effects in quantum field theory

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    We have constructed a quantum field theory in a finite box, with periodic boundary conditions, using the hypothesis that particles living in a finite box are created and/or annihilated by the creation and/or annihilation operators, respectively, of a quantum harmonic oscillator on a circle. An expression for the effective coupling constant is obtained showing explicitly its dependence on the dimension of the box.Comment: 12 pages, Late

    The electric vehicle in smart homes: a review and future perspectives

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    The electric mobility dissemination is forcing the adoption of new technologies and operation paradigms, not only focusing on smart grids, but also on smart homes. In fact, the emerging technologies for smart homes are also altering the conventional grids toward smart grids. By combining the key pillars of electric mobility and smart homes, this paper characterizes the paradigms of the electric vehicle (EV) in smart homes, presenting a review about the state of the art and establishing a relation with future perspectives. Since the smart home must be prepared to deal with the necessities of the EV, the analysis of both on board and off board battery charging systems are considered in the paper. Moreover, the in-clusion of renewable energy sources, energy storage systems, and dc electrical appliances in smart homes towards sustainability is also considered in this paper, but framed in the perspective of an EV off board battery charging system. As a pertinent contribution, this paper offers future perspectives for the EV in smart homes, including the possibility of ac, dc, and hybrid smart homes. Covering all of these aspects, exemplificative and key results are presented based on numerical simulations and experimental results obtained with a proof of concept prototype.FCT – Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2019. This work has been supported by the FCT Project newERA4GRIDs PTDC/EEI-EEE/30283/2017, and by the FCT Project DAIPESEV PTDC/EEI-EEE/30382/2017. Tiago Sousa is supported by the doctoral scholarship SFRH/BD/134353/2017 granted by FC

    Development of geoprocessing applications for the Pantanal using automated compositions of web services.

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    This paper presents an approach to develop geo-processing applications for the Pantanal region using automated compositions of geographic Web Services. The procedure for the automatic construction of these compositions is based on rules of geo-data quality requirements which indicate the conditions for geo-data use by a geo-processing functionality. These rules can be defined to describe geospatial characteristics to select suitable geo-processing services for use in the Pantanal region. Therefore this approach produces more robust and reliable service compositions, generating better quality geo-data when compared with other composition approaches.Número especial

    Desenvolvimento de aplicações em geoprocessamento usando composição automatizada de serviços geográfcos.

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    Este trabalho apresenta uma abordagem para construção de aplicações em geoprocessamento através da composição automatizada de Web Services geográfcos. O problema de composição é modelado como um problema de planejamento condicional onde, regras semânticas de requisitos de qualidade de geodados são utilizadas como uma indicação de condições de uso de um dado por uma funcionalidade de geoprocessamento. Esta abordagem permite a criação de composições de serviços mais robustas, confáveis e capazes de produzir geodados de melhor qualidade.Geopantanal 2010

    Shell we cook it? An experimental approach to the microarchaeological record of shellfish roasting

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    In this paper, we investigate the microarchaeological traces and archaeological visibility of shellfish cooking activities through a series of experimental procedures with direct roasting using wood-fueled fires and controlled heating in a muffle furnace. An interdisciplinary geoarchaeological approach, combining micromorphology, FTIR (in transmission and ATR collection modes), TGA and XRD, was used to establish a baseline on the mineralogical transformation of heated shells from aragonite to calcite and diagnostic sedimentary traces produced by roasting fire features. Our experimental design focused on three main types of roasting procedures: the construction of shallow depressions with heated rocks (pebble cuvette experiments), placing shellfish on top of hot embers and ashes (fire below experiment), and by kindling short-lived fires on top of shellfish (fire above experiments). Our results suggest that similar shellfish roasting procedures will largely create microstratigraphic signatures of anthropogenically reworked combusted material spatially “disconnected” from the actual combustion locus. The construction of shallow earth ovens might entail an increased archaeological visibility, and some diagnostic signatures of in situ hearths can be obtained by fire below roasting activities. We also show that macroscopic visual modifications and mineralogical characterization of discarded shellfish might be indicative of specific cooking activities versus secondary burning

    Two-dimensional superconductivity at the (111)LaAlO3_3/SrTiO3_3 interface

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    We report on the discovery and transport study of the superconducting ground state present at the (111)LaAlO3_3/SrTiO3_3 interface. The superconducting transition is consistent with a Berezinskii-Kosterlitz-Thouless transition and its 2D nature is further corroborated by the anisotropy of the critical magnetic field, as calculated by Tinkham. The estimated superconducting layer thickness and coherence length are 10 nm and 60 nm, respectively. The results of this work provide a new platform to clarify the microscopic details of superconductivity at LaAlO3_3/SrTiO3_3 interfaces, in particular in what concerns the link with orbital symmetry.Comment: 4 pages, 4 figure

    Mineralization of 14C-diuron by Acinetobacter baumannii.

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    The diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] is an herbicide used in sugarcane and other crops. This work evaluated the mineralization of the herbicide diuron by Acinetobacter baumannii and also was developed protocols for extraction and quantification of 14C-diuron. The strain (D12-12), isolated from rhizosphere of sugarcane, grown in soils treated with the herbicide, was cultivated in mineral media J.E. plus diuron at 20 ug/ml and plus 14C-diuron (specific activity = 2.43 MBq/mg) applied at 39,3215 KBq/50 ml, and incubated for 32 days in duplicate. The 14C-diuron extraction was carried out on C-18 SEP-PAK columns, resuspended in scintillation cocktail and the activity determined by liquid scintillation counting. The recuperation of diuron was more than 96,2% and 14CO2 accumulated after 32 days was 1,77%

    An instability of higher-dimensional rotating black holes

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    We present the first example of a linearized gravitational instability of an asymptotically flat vacuum black hole. We study perturbations of a Myers-Perry black hole with equal angular momenta in an odd number of dimensions. We find no evidence of any instability in five or seven dimensions, but in nine dimensions, for sufficiently rapid rotation, we find perturbations that grow exponentially in time. The onset of instability is associated with the appearance of time-independent perturbations which generically break all but one of the rotational symmetries. This is interpreted as evidence for the existence of a new 70-parameter family of black hole solutions with only a single rotational symmetry. We also present results for the Gregory-Laflamme instability of rotating black strings, demonstrating that rotation makes black strings more unstable.Comment: 38 pages, 13 figure
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