DBI equations and holographic dc conductivity

We provide a simple method for writing the Dirac-Born-Infeld equations of a Dp-brane in an arbitrary static background whose metric depends only on the holographic radial coordinate z. Using this method we revisit the Karch-O'Bannon procedure to calculate the dc conductivity in the presence of constant electric and magnetic fields for backgrounds where the boundary is four- or three-dimensional and satisfies homogeneity and isotropy. We find a frame-independent expression for the dc conductivity tensor. For particular backgrounds we recover previous results on holographic metals and strange metals. © 2013 American Physical Society.

Deposition and photo-induced electrical resistivity of dip-coated NiO thin films from a precipitation process

Thin films of the semiconductor NiO are deposited using a straightforward combination of simple and versatile techniques: the co-precipitation in aqueous media along with the dip- coating process. The obtained material is characterized by gravimetric/differential thermal analysis (TG-DTA) and X-ray diffraction technique. TG curve shows 30 % of total mass loss, whereas DTA indicates the formation of the NiO phase about 578 K (305 C). X-ray diffraction (XRD) data confirms the FCC crystalline phase of NiO, whose crystallinity increases with thermal annealing temperature. UV-Vis optical absorption measurements are carried out for films deposited on quartz substrate in order to avoid the masking of bandgap evaluation by substrate spectra overlapping. The evaluated bandgap is about 3.0 eV. Current-voltage (I-V) curves measured for different temperatures as well as the temperature-dependent resistivity data show typical semiconductor behavior with the resistivity increasing with the decreasing of temperature. The Arrhenius plot reveals a level 233 meV above the conduction band top, which was attributed to Ni2+ vacancy level, responsible for the p-type electrical nature of NiO, even in undoped samples. Light irradiation on the films leads to a remarkable behavior, because above bandgap light induced a resistivity increase, despite the electron-hole generation. This performance was associated with excitation of the Ni 2+ vacancy level, due to the proximity between energy levels. © 2012 Springer Science+Business Media New York.

CaCu3Ti4O12 thin films with non-linear resistivity deposited by RF-sputtering

Calcium copper titanate, CaCu3Ti4O12, CCTO, thin films with polycrystalline nature have been deposited by RF sputtering on Pt/Ti/SiO2/Si (100) substrates at a room temperature followed by annealing at 600 °C for 2 h in a conventional furnace. The CCTO thin film present a cubic structure with lattice parameter a = 7.379 ±0.001 Å free of secondary phases. The observed electrical features of CCTO thin films are highly dependent on the [CaO12], [CaO 4], [CuO11], [CuO11Vx 0] and [TiO5.VO] clusters. The CCTO film capacitor showed a dielectric loss of 0.40 and a dielectric permittivity of 70 at 1 kHz. The J-V behavior is completely symmetrical, regardless of whether the conduction is limited by interfacial barriers or by bulk-like mechanisms. © 2013 Elsevier B.V. All rights reserved.

The resistivity piezocone for high resolution geo-environmental site investigation: A Brazilian example

A suit able decision-making on managing a contaminated site characterization program is strongly dependent of the diagnosis process. A detailed diagnosis can be done based on a Conceptual Site Model (CSM) elaboration using high resolution site characterization tools. The piezocone (CPTu) test is a high resolution tool which allows attaching several specific sensors, like the resistivity probe. This hybrid device is called the resistivity piezocone (RCPTu). A simulated geo-environmental site characterization program was performed on an erosion site using different tools (direct push tools soil samplers, hollow stem auger (HSA) drilling and RCPTu tests) to develop the CSM for a site similar to the Brazilian conditions. It was observed a good agreement between the site profiles interpreted by the different methods. The resistivity sensor attached to the piezocone improved the interpretation and the decision-making process on site was significantly better for the CSM elaboration. The RCPTu test data also allowed identifying the hydrogeological heterogeneities. The present study shows that the RCPTu test is also a useful and powerful tool to development an accurate CSM in a Brazilian condition, especially in an approach that prioritizes high resolution geo-environmental investigation. © 2013 Taylor & Francis Group.

Observer-based control design for switched affine systems and applications to DC-DC converters

This paper deals with the problem of establishing a state estimator for switched affine systems. For that matter, a modification on the Luenberger observer is proposed, the switched Luenberger observer, whose idea is to design one output gain matrix for each mode of the original system. The efficiency of the proposed method relies on a simplification on estimation error which is proved always valid, guaranteeing the estimation error to asymptotically converge to zero, for any initial state and switching law. Next, a dynamic output-dependent switching law is formulated. Then, design methodologies using linear matrix inequalities are proposed, which, to the authors's knowledge, have not yet been applied to this problem. Finally, observers for DC-DC converters are designed and simulated as application examples. © 2013 Brazilian Society for Automatics - SBA.

Mating in the pseudogamic apomictic Anemopaegma acutifolium DC: Another case of pseudo-self-compatibility in Bignoniaceae?

Self-compatibility in apomictic pseudogamic species is considered fundamental to assure reproduction by seeds in extreme situations, making apomictic species more advantageous than sexual ones in these scenarios. Anemopaegma acutifolium is a polyploidy, apomictic sporophytic species with no endosperm development in ovules of unpollinated pistils, which indicates obligate pseudogamy. Thus, the aim of the present work is to study the breeding system and post-pollination events to test if there is similar pseudogamous development irrespective of pollination treatment. We analysed fruit and seed set obtained in controlled experimental pollinations, as well as embryo number per seed, and the progress of ovule penetration, fertilisation and early endosperm development between self- and cross-pollinated pistils. We found that the species is self-fertile and that spontaneous selfing fruit set is also possible, although emasculated flowers never form fruits. Selfed pistils were as efficient as crossed ones for all parameters analysed, except for a delay in endosperm development observed in the former that may be an effect of the late-acting self-incompatibility. Therefore, the avoidance of selfed pistil abortion seems to be promoted by the presence of adventitious embryos and a normal endosperm. We conclude that A. acutifolium shows apomixis-related pseudo-self-compatibility, as in other self-fertile apomictic species of Bignoniaceae, which confer reproductive assurance and increases fruit-set and persistence ability in fast-changing tropical habitats. © 2012 German Botanical Society and The Royal Botanical Society of the Netherlands.

Germinação de sementes de Passiflora setacea DC: temperatura, luz e reguladores vegetais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efeito da predação por Acanthoscelides schrankiae(Coleoptera: Bruchidae) e de altas temperaturas na germinação de sementes de Mimosa bimucronata (DC.) Kuntze (Fabaceae: Mimosoideae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Compostos orgânicos como substratos na formação de mudas de ipê amarelo [Tabebuia chrysotricha (Mart. ex DC) Standl.] irrigado com água residuária

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Aplicação do eletrocapilaridade na manipulação de microgotas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cordia verbenacea DC: perfil morfo-anatômico, histoquímico, farmacognóstico e avaliação da atividade anti-candida do extrato hidroetanólico e suas frações

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efeitos do extrato de Baccharis dracunculifolia DC em diferentes mediadores da inflamação intestinal induzida por TNBS em ratos

Pós-graduação em Ciências Biológicas (Farmacologia) - IBB

Estudo farmacognóstico e avaliação das atividades antibacteriana e imunomoduladora de Melampodium divaricatum (Rich. In Pers) DC. (Asteraceae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Transporte e características de onda de densidade de carga na ludwigita nomometálica Fe3O2BO3

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Marcha de absorção de macronutrientes e acúmulo de fenólicos totais em [(Baccharis Trimera (Less.) DC.] var. CPQBA-1, sob diferentes podas no plantio

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)