Sedimentary heterogeneity and petrophysical characterization of Barremian tsunami and barrier island/inlet deposits: The Aliaga outcrop as a reservoir analogue (Galve sub-basin, eastern Spain)

The present study examined two sandstone deposits in the Aliaga outcrop as a reservoir analogue over a distance of 200-m-long and attempted to establish a correlation between sand facies and the petrophysical properties of the sandstones in order to investigate the reservoir heterogeneity. The Aliaga reservoir analogue represents the upper part of Camarillas Fm., deposited during the Barremian synrift phase of the Galve sub-basin (Iberian Basin, Spain). It is characterized by a transitional sedimentary interval from sandy-dominant deposits to carbonate-dominant deposits, which were deposited under the same palaeoenvironmental conditions (in relation to systems of back-barrier sedimentation). The description of the Aliaga outcrop provided here consists of lithological descriptions of two sandstone deposits: a tsunami and a barrier island/inlet, at both mesoscopic (decimetres to tens of metres) and microscopic scales (millimetres to centimetres). Both deposits recognized at the basin scale were described in terms of sand grain size, sand sorting and cementation; further cores were drilled along outcrop to collect samples for porosity and permeability measurements. Both sandstone reservoirs are the result of different sedimentary processes that determined facies characteristics, as the different petrophysical properties observed in these deposits. Consequently, the sedimentary process controls the heterogeneity of the sandstones facies and thus, the sand heterogeneity controls the distribution of the petrophysical properties. The classification of sand facies in terms of sand sorting seems to be more appropriate for describing sand heterogeneity; accordingly, petrophysical parameters in both deposits were also influenced by sand sorting. The sand facies and petrophysics heterogeneity of the described deposits can be hierarchically ordered. First-order heterogeneity is related to the basin scale, second-order heterogeneity is related to genesis and the conditions of sediment deposition, and third-order heterogeneity is related to synsedimentary faults and/or post-sedimentation events.This research is a contribution to the project: Análisis de Cuencas Sedimentarias Continentales, of the Gobierno de Aragón, the Análisis de Cuencas Sedimentarias Group of the UCM-CAM, and the projects CGL2011-23717 (Ministerio de Ciencia e Innovación of the Spanish Government and FEDER) and UZ2015-CIE-10 (University of Zaragoza). Additional financial support was provided by a Cnpq (Conselho Nacional de Pesquisa e Desenvolvimento Tecnologico, Brasil) Research Grant (200147/2011-0) and an IAS Schema 1st session 2014 Postgraduate Grant to F. Veloso.Peer reviewe

Pressure effect in the X-ray intrinsic position resolution in noble gases and mixtures

A study of the gas pressure effect in the position resolution of an interacting X- or gamma-ray photon in a gas medium is performed. The intrinsic position resolution for pure noble gases (Argon and Xenon) and their mixtures with CO2 and CH4 were calculated for several gas pressures (1-10bar) and for photon energies between 5.4 and 60.0 keV, being possible to establish a linear match between the intrinsic position resolution and the inverse of the gas pressure in that energy range. In order to evaluate the quality of the method here described, a comparison between the available experimental data and the calculated one in this work, is done and discussed. In the majority of the cases, a strong agreement is observed

The Resistive-Plate WELL with Argon mixtures - a robust gaseous radiation detector

A thin single-element THGEM-based, Resistive-Plate WELL (RPWELL) detector was operated with 150 GeV/c muon and pion beams in Ne/(5%CH$_4$), Ar/(5%CH$_4$) and Ar/(7%CO$_2$); signals were recorded with 1 cm$^2$ square pads and SRS/APV25 electronics. Detection efficiency values greater than 98% were reached in all the gas mixtures, at average pad multiplicity of 1.2. The use of the 10$^9${\Omega}cm resistive plate resulted in a completely discharge-free operation also in intense pion beams. The efficiency remained essentially constant at 98-99% up to fluxes of $\sim$10$^4$Hz/cm$^2$, dropping by a few % when approaching 10$^5$ Hz/cm$^2$. These results pave the way towards cost-effective, robust, efficient, large-scale detectors for a variety of applications in future particle, astro-particle and applied fields. A potential target application is digital hadron calorimetry.Comment: presented at the 2016 VIenna Conf. On instrumentation. Submitted to the Conference proceeding

Simulation of VUV electroluminescence in micropattern gaseous detectors: the case of GEM and MHSP

Electroluminescence produced during avalanche development in gaseous avalanche detectors is an useful information for triggering, calorimetry and tracking in gaseous detectors. Noble gases present high electroluminescence yields, emitting mainly in the VUV region. The photons can provide signal readout if appropriate photosensors are used. Micropattern gaseous detectors are good candidates for signal amplification in high background and/or low rate experiments due to their high electroluminescence yields and radiopurity. In this work, the VUV light responses of the Gas Electron Multiplier and of the Micro-Hole Strip Plate, working with pure xenon, are simulated and studied in detail using a new and versatile C++ toolkit. It is shown that the solid angle subtended by a photosensor placed below the microstructures depends on the operating conditions. The obtained absolute EL yields, determined for different gas pressures and as functions of the applied voltage, are compared with those determined experimentally.Comment: Accepted for publication in Journal of Instrumentatio

First in-beam studies of a Resistive-Plate WELL gaseous multiplier

We present the results of the first in-beam studies of a medium size (10$\times$10 cm$^2$) Resistive-Plate WELL (RPWELL): a single-sided THGEM coupled to a pad anode through a resistive layer of high bulk resistivity ($\sim$10$^9 \Omega$cm). The 6.2~mm thick (excluding readout electronics) single-stage detector was studied with 150~GeV muons and pions. Signals were recorded from 1$\times$1 cm$^2$ square copper pads with APV25-SRS readout electronics. The single-element detector was operated in Ne\(5% $\mathrm{CH_{4}}$) at a gas gain of a few times 10$^4$, reaching 99$\%$ detection efficiency at average pad multiplicity of $\sim$1.2. Operation at particle fluxes up to $\sim$10$^4$ Hz/cm$^2$ resulted in $\sim$23$\%$ gain drop leading to $\sim$5$\%$ efficiency loss. The striking feature was the discharge-free operation, also in intense pion beams. These results pave the way towards robust, efficient large-scale detectors for applications requiring economic solutions at moderate spatial and energy resolutions.Comment: Accepted by JINS

A dynamic method for charging-up calculations: the case of GEM

The simulation of Micro Pattern Gaseous Detectors (MPGDs) signal response is an important and powerful tool for the design and optimization of such detectors. However, several attempts to simulate exactly the effective charge gain have not been completely successful. Namely, the gain stability over time has not been fully understood. Charging-up of the insulator surfaces have been pointed as one of the responsible for the difference between experimental and Monte Carlo results. This work describes two iterative methods to simulate the charging-up in one MPGD device, the Gas Electron Multiplier (GEM). The first method uses a constant step for avalanches time evolution, very detailed, but slower to compute. The second method uses a dynamic step that improves the computing time. Good agreement between both methods was reached. Despite of comparison with experimental results shows that charging-up plays an important role in detectors operation, should not be the only responsible for the difference between simulated and measured effective gain, but explains the time evolution in the effective gain.Comment: Minor changes in grammatical statements and inclusion of some important information about experimental setup at section "Comparison with experimental results

Conjectures of Mathematical Logic and Educational Games for Basic Education Based on the Guidelines of NCP, NCG and NBC

Current technological advances allow us to create, adapt or simply use numerous resources to achieve improvements in teaching-learning. The purpose of this article is to show the result of an analysis of the current normative documents and recommendations for national education in Brazil (National Curricular Guidelines - National Curricular Parameters and National Common Curricular Base), primary and secondary education, regarding the contents recommended in mathematical logic, complementing with the analysis of a pedagogical political project of the fundamental education of a public school, to verify the existence of this content, in it. From this analysis and reflection on the importance of educational games in teaching, the article proposes the development of an educational game especially to assist in teaching the functionalities on the symbols of logic. It highlights the contribution of this game to the teaching-learning of these rules and symbols and, finally, concludes by showing the importance of this activity in the educational process

Influência de diferentes densidades de plantio sobre o desenvolvimento do primeiro ciclo da bananeira 'Pacovan'.

Entre as fruteiras tropicais de relevante importância econômica mundial, destaca-se a bananeira (Musa ssp.), apresentando o mais alto índice de consumo "per capita" entre as frutas tropicais (Sebrae, 2000). Dados referentes ao ano de 1998 destacam o Brasil como o terceiro maior produtor de bananas, com produção anual em torno de 5,5 milhões de toneladas, depois da Índia e Equador, com 10,2 e 7,5 milhões de toneladas por ano, respectivamente (FAO, 1999). A bananeira é uma planta tipicamente tropical, a qual exige calor constante, precipitações bem distribuídas e elevada umidade para seu bom desenvolvimento e produção (Alves, 1999). O espaçamento de plantio é um fator importante no sistema de produção de banana, pois a adequada escolha da densidade de plantio proporciona melhor desenvolvimento e produção da cultura, gerando um maior lucro para o produtor. Os sistemas de espaçamentos de plantio normalmente conduzem a um bom aproveitamento da luz, solo, mão-de-obra e insumos, o que resulta na melhoria substancial de produtividade e qualidade do produto (Pereira et al. 1999; Pereira et al. 2000). A escolha da densidade ótima de plantio para bananeira é função de vários fatores, tais como: cultivar, fertilidade do solo, tipo de muda, seleção de seguidores (rebentos), nível de tecnologia aplicada, controle de plantas daninhas, velocidade do vento, topografia, aspectos econômicos, entre outros (Stover & Simmonds, 1987; Soto Ballestero, 1992). Vários estudos sobre densidade de plantio têm mostrado a sua influência sobre o ciclo da cultura. Autores como Daniells et al. (1985), Robinson & Nel (1989) e Lichtemberg et al. (1990) observaram que, de maneira geral, o aumento da densidade ocasiona um alongamento no ciclo da banana. De acordo com Lichtemberg et al. (1997), esta resposta é mais freqüente após o primeiro ciclo, onde a competição interplantas começa a ser intensificada. O aumento do ciclo conduz, invariavelmente, a uma redução progressiva na produtividade dos bananais submetidos a plantios mais densos, quando avaliada em t ha-1 ano-1 (Robinson & Nel, 1989). Vários são os fatores que influenciam o desenvolvimento da bananeira, sendo estes variáveis de acordo com a cultivar utilizada, as condições climáticas, edáficas, densidade de plantio, tratos culturais, entre outros fatores. Os estudos relacionando densidade de plantio e desenvolvimento da planta são de relevante importância, já que estes fatores irão influenciar a produtividade e qualidade dos frutos. O presente trabalho teve como objetivo avaliar o efeito do adensamento sobre algumas características de desenvolvimento na cultura da bananeira

Simulation of gain stability of THGEM gas-avalanche particle detectors

Charging-up processes affecting gain stability in Thick Gas Electron Multipliers (THGEM) were studied with a dedicated simulation toolkit. Integrated with Garfield++, it provides an effective platform for systematic phenomenological studies of charging-up processes in MPGD detectors. We describe the simulation tool and the fine-tuning of the step-size required for the algorithm convergence, in relation to physical parameters. Simulation results of gain stability over time in THGEM detectors are presented, exploring the role of electrode-thickness and applied voltage on its evolution. The results show that the total amount of irradiated charge through electrode's hole needed for reaching gain stabilization is in the range of tens to hundreds of pC, depending on the detector geometry and operational voltage. These results are in agreement with experimental observations presented previously

Propriedades químicas de um latossolo amarelo cultivado com pastagens na Amazônia Oriental.

A pesquisa foi conduzida com o objetivo de avaliar as modificações das propriedades químicas de um Latossolo Amarelo com cultivo de pastagens, submetidos a dois modelos de sistemas rotacionados, nos períodos chuvoso e seco, um com Brachiaria brizantha e o outro com Panicum maximum, nos anos de 1996 e 1997. O delineamento experimental utilizado foi em blocos casualizados, com os tratamentos dispostos num esquema de parcelas subdivididas, com doze repetições. As parcelas foram constituídas pelas forrageiras braquiarão e tobiatã e as subparcelas foram constituídas pelos períodos chuvoso e seco dentro de cada ano. Para o estudo das propriedades químicas do solo, foram coletadas amostras nos períodos chuvoso e seco. O material orgânico incorporado ao solo através de restos de vegetais e a presença de excremento animal alterou as propriedades químicas nos anos estudados. Os teores de Ca, Mg, K, P, MO e o valor de pH foram maiores no ano de 1997. Teores mais elevados de Ca e Mg foram obtidos no sistema de pastejo com tobiatã do que no sistema com braquiarão. No período chuvoso os teores de Mg, K, MO e o valor de pH foram maiores, com exceção de P e Ca para o ano de 1997