Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99


Any time

2019 ( 224 )

2018 ( 372 )

2017 ( 355 )

2016 ( 488 )

Custom range...

Search Results: 1 - 10 of 265074 matches for " álvaro C;Silva "
All listed articles are free for downloading (OA Articles)
Page 1 /265074
Display every page Item
Qualidade física do solo em pomar de laranjeira no noroeste do paraná com manejo da cobertura permanente na entrelinha
Fidalski, Jonez;Tormena, Cássio Antonio;Silva, álvaro Pires da;
Revista Brasileira de Ciência do Solo , 2007, DOI: 10.1590/S0100-06832007000300002
Abstract: the traffic of agricultural machinery and soil compaction occur near the canopy of citrus trees, which increases soil physical restrictions to root growth. soil management strategies include the use of permanent groundcover in the interrows of orange tree plantations, although the effects of these practices on the soil physical quality are largely unknown. the objective of this study was to assess the impact of groundcover management systems on some indicators of soil physical quality for orange tree orchards. the study was performed in a long-term experiment with 'pêra' orange grafted onto 'rangpur' lime combined with groundcover systems, established in 1993, in the alto paraná county, northwestern paraná state, brazil, in a typic paleudult with a sandy surface horizon. bahiagrass (paspalum notatum) or perennial peanut (arachis pintoi) groundcover treatments were compared with the usual management in which weeds are controlled by post-emergence herbicide. the experimental design consisted of randomized blocks with three replications. in may 2003, soil samples were collected from under and between the wheel tracks. the following indicators were assessed in undisturbed soil samples from the mid 0-15 cm layer: water content at field capacity, total porosity and bulk density. the data were used to estimate soil aeration and water storage capacity indicators. disturbed soil samples were collected in the 0-5 cm and 10-15 cm depths to measure the organic carbon content and calculate the soil organic carbon stratification ratio. the soil aeration capacity, water storage capacity and organic carbon stratification ratio were efficient indicators to evaluate groundcover management systems in citrus. bahiagrass maintained better soil physical conditions both under and between wheel tracks. the soil physical quality was negatively affected under the wheel tracks on perennial peanut groundcover and under the wheel tracks and between tracks on the usual control of spontaneous veg
Least limiting water range and physical quality of soil under groundcover management systems in citrus
Fidalski, Jonez;Tormena, Cássio Antonio;Silva, álvaro Pires da;
Scientia Agricola , 2010, DOI: 10.1590/S0103-90162010000400012
Abstract: machinery-based farming operations used for perennial fruit crops often damage soils, particularly if the soil is wet and prone to compaction. we hypothesized that perennial vegetation growing in the interrows of orange orchards can mitigate the soil physical degradation from machinery traffic. the objective of this study was to investigate the effects of different groundcover management systems on the soil physical quality indicators including the least limiting water range (llwr). an experiment was started in 1993 in a typic paleudult to evaluate three groundcover management systems: bahia grass (paspalum notatum) with mowing, perennial peanut (arachis pintoi), and natural regrowth in which weeds were controlled by herbicide. the experimental design was randomized complete block with three replications. in may 2003, 216 undisturbed soil samples were collected at 0-0.15-m depths under and between wheel tracks in the orchard interrows. the soil bulk density, soil organic carbon content, resistance to penetration, soil water retention curve and soil resistance to penetration curve were determined in order to estimate the llwr. the higher llwr under wheel tracks in bahia grass compared to perennial peanut or natural regrowth suggest that a better soil physical quality was achieved with bahia grass.
Evaluation of the sticky MosquiTRAP? for detecting Aedes (Stegomyia) aegypti (L.) (Diptera: Culicidae) during the dry season in Belo Horizonte, Minas Gerais, Brazil
Gama, Renata A.;Silva, Eric M.;Silva, Ivoneide M.;Resende, Marcelo C.;Eiras, álvaro E.;
Neotropical Entomology , 2007, DOI: 10.1590/S1519-566X2007000200018
Abstract: mosquitrap? is a sticky trap specifically designed to capture gravid females of aedes aegypti (l.) and allows the identification of the mosquito in the field during the inspection of the trap. this study aims to compare this sticky trap to larval and ovitrap surveys for field monitoring of a. aegypti during the dry season. the study was conducted from march to june of 2003 in 20 blocks of the district of itapo?, belo horizonte, mg. the traps were monitored every week while the larval survey was conducted on a monthly basis. the larval index: premise index (pi) and breteau index (bi) had equal values throughout the experiment (1.72 in the first two months and zero in the last two). the container index (ci) during the first two months was 0.09 and 0.1%, respectively and zero in the last two. the ovitrap positive index (opi) ranged from 16.7 to 76.9%, and the mosquitrap positive index (mpi) ranged from 0 to 31.5%. the egg density index (edi) ranged from 26.6 to 82.8, while the adult density index ranged from 0 to 1.6 throughout the experiment. temperature and rainfall did not affect the positive and density indices, although these environmental variables seemed to have affected the larvae indices. although the mosquitrap caught a low number of aedes mosquitoes during the study, it was more sensitive than the larval survey to detect the presence of aedes mosquitoes.
Influência da carga mecanica de máquina sobre propriedades físicas de um cambissolo háplico
Cavalieri, Karina Maria Vieira;Silva, álvaro Pires da;Arvidsson, Johan;Tormena, Cássio Antonio;
Revista Brasileira de Ciência do Solo , 2009, DOI: 10.1590/S0100-06832009000300001
Abstract: the objective of this study was to evaluate the effects of different mechanical loads on soil physical properties of a eutric cambisol with loam sandy texture. the soil load distribution (kpa) was measured in situ by sensors placed in different soil layers. the soil physical properties evaluated were the bulk density (ds) and the soil penetration resistance (rp) on sugarbeet (beta vulgaris l.) row and interrow down to 0.30 m depth. the treatments were: without extra pressure exerted by the sowing machine, or no-compaction (sc); low pressure exerted by the sowing machine, named low load (bc); high pressure exerted the sowing machine, named high load (ac) and load pressure exerted by the tractor wheels used in the seedbed preparation, or tractor load (ct). the soil load distribution data indicated that the 0-0.10 m layer had soil stresses values higher than 120 kpa, which are considered very high. the increase on soil stresses from treatments sc to ac caused higher stress on topsoil than in the 0.10-0.20 m depth, while that under ct treatment showed higher stress at the 0.10-0.20 m layer. as a consequence of the soil stress load it was verified an increase on ds in the more superficial soil layer (0-10 cm), and it followed the sequence: sc
Quantifica??o da resistência tênsil e da friabilidade de um latossolo vermelho distroférrico sob plantio direto
Tormena, Cássio Antonio;Araújo, Marcelo Alessandro;Fidalski, Jonez;Imhoff, Silvia;Silva, álvaro Pires da;
Revista Brasileira de Ciência do Solo , 2008, DOI: 10.1590/S0100-06832008000300004
Abstract: the soil structural quality is important for plant emergence as well as for crop growth, development and yield. a wide range of soil tensile strength values indicates that soil structure conditions meet these requirements. the objective of this study was to evaluate the tensile strength and friability of an oxisol (acrudox) under no-tillage with crop rotation and crop succession. the soil management treatments consisted of: crop succession with wheat and soybean (sds); crop rotation with corn-oats-soybean-oats-soybean-wheat (sdr) and sdr plus periodic soil chiseling (sde). ten soil blocks (0.15 x 0.20 x 0.10 m) were randomly collected from the 0-0.20 m layer for each treatment, on two sampling dates (october 2003 and april 2004). the soil tensile strength and soil friability was estimated in 450 soil aggregates from each treatment and sampling date. the soil organic carbon content of the aggregates was also measured. there was no effect of soil organic carbon on soil tensile strength and friability. results showed lower tensile strength in sde soil collected in 2003. crop succession (sds) temporarily changed the friability classification from very friable to friable. crop rotation (sdr) was effective in maintaining the soil structure at the very friable class, resulting in a better structure and soil physical quality. the parameters tensile strength and friability proved sensitive enough to evaluate soil structural quality under the crop management systems studied.
Fun??es de pedotransferência para as curvas de reten??o de água e de resistência do solo à penetra??o
Silva, álvaro Pires da;Tormena, Cássio Antonio;Fidalski, Jonez;Imhoff, Silvia;
Revista Brasileira de Ciência do Solo , 2008, DOI: 10.1590/S0100-06832008000100001
Abstract: pedotransfer functions (ptfs) are useful tools to obtain estimates of soil physical properties such as the soil water retention curve (swrc) and the soil resistance to penetration curve (srpc), which are important inherent soil properties and difficult to measure. most of the studies in the literature report ptfs only in relation to swrc estimates. an important and necessary advance in this research area would be the development of ptfs for a simultaneous estimation of the swrc and srpc, which is the objective of this paper. an area with wide variation in soil texture was selected where 180 samples were collected for the measurement of swrc, srpc, bulk density, soil texture and organic carbon content. both swrc and the srpc were successfully estimated with the coefficient of determination (r2 > 0.9). clay content was the most important soil property to dewtermine the ptfs and its effect on swrc and srpc was demonstrated.
Quantification of the soil physical quality of a tropical oxisol using the S index
Tormena, Cássio Antonio;Silva, álvaro Pires da;Imhoff, Silvia Del Carmen;Dexter, Anthony Roger;
Scientia Agricola , 2008, DOI: 10.1590/S0103-90162008000100008
Abstract: soil physical quality is fundamental for the sustainability of agro ecosystems. soil physical quality assessment must be developed using parameters that describe physical behavior. s, a new soil physical parameter has recently been introduced for assessing the soil physical quality. a good soil physical quality has been associated with values of s > 0.035 in soils from temperate climates. however, s has not been evaluated in tropical soils yet. therefore we tested the hypothesis that s is a reliable soil physical quality indicator of a typic hapludox cropped with maize under no-tillage (nt) and conventional tillage (ct). undisturbed samples were collected from each tillage system in the row and interrow positions. soil bulk density was determined in the samples and the s parameter was calculated using a pedotransfer function from the same samples. the parameter s was able to differentiate tillage and position with snt < sct independent of the row and interrow sampling positions. higher s values were verified in row position than in the interrow in both tillage systems. with the use of a pedotransfer function it was also possible to establish a negative relationship between s and soil compaction. the results confirmed our hypothesis and suggest that further studies should be carried out to evaluate s in other tropical soils and management systems.
Organizational performance from the social, environmental and corporate image perspectives: a study of the six largest Brazilian banks Análise do desempenho organizacional sob as perspectivas socioambiental e de imagem corporativa: um estudo apoiado em DEA sobre os seis maiores bancos no Brasil
Marcelo álvaro da Silva Macedo,Fabrício Carvalho Cípola,Ant?nio Francisco Ritter Ferreira
Rege : Revista de Gest?o , 2008,
Abstract: Data envelopment analysis of information from the social balance sheets and about corporate images of these six banks was made for characteristics related to performance in two respects. First was the use of the social and environmental investment capacity and second was the achievement of corporate image gains from this investment. The relationship between this investment capacity and results was studied and compared to identify the efficiency and performance of each bank. Results show that the "Caixa Economica Federal" and the "Banco do Brasil" were the best at converting investment capacity into social and environmental benefits, while "Santander-Banespa" and "Bradesco" were best in terms of the capacity of usage of social and environmental investments to achieve image benefits. Consolidating these aspects over time in a multi-dimensional analysis, "Banco do Brasil" stands out. Este trabalho tem como objetivo, através da aplica o da análise envoltória de dados às informa es dos balan os sociais e sobre imagem corporativa dos bancos que fazem parte da amostra, expor características do desempenho destes sob duas óticas: primeiramente, a da utiliza o da capacidade de investimento socioambiental e, depois, a da obten o de ganhos de imagem corporativa a partir desse investimento. A lógica do estudo é observar a rela o entre capacidade de investimento e benefícios socioambientais. De acordo com essa lógica, quanto maiores forem os benefícios para uma menor capacidade de investimento, maior será a eficiência e, por conseguinte, o desempenho socioambiental da empresa. Além disso, pretende-se verificar, a partir da hipótese de que investimentos socioambientais geram benefícios de imagem, qual a eficiência de convers o desses investimentos em ganhos de imagem corporativa para cada institui o analisada. Os resultados mostram que a CEF e o BB s o os destaques positivos na convers o de capacidade de investimento em benefícios socioambientais, enquanto o Santander-Banespa e o Bradesco s o os melhores em capacidade de utiliza o de investimentos socioambientais na obten o de benefícios de imagem. Na consolida o dos modelos, ao longo do período, em uma análise multidimensional, destaca-se o BB.
Concep es de pedagogia universitária uma análise do Questionário de Avalia o do Ensino Ministrado na Universidade do Minho
Maria Melo do Céu,José Luís Silva,álvaro Gomes,Flávia Vieira
Revista Portuguesa de Educa??o , 2000,
Abstract: The project Conceptions of University Pedagogy a Study in the University of Minho seeks to identify conceptions of pedagogy in this context, by focussing on instances of the official regulatory discourse and on the opinions of teachers and students from all the initial training courses. The authors present the results of the first stage of the project, by analysing an instrument used within this University since 1991, whereby students evaluate teaching, seeking to question its function, object and implications as a regulation tool. We conclude that the conception of pedagogy that underlies the questionnaire undermines its pedagogical value.
Periodicidade de captura de Anopheles darlingi Root (Diptera: Culicidae) em Porto Velho, RO
Gama, Renata A;Santos, Roseli L C;Santos, Fátima dos;Silva, Ivoneide M;Resende, Marcelo C;Eiras, álvaro E;
Neotropical Entomology , 2009, DOI: 10.1590/S1519-566X2009000500019
Abstract: anopheles darlingi root is the principal malaria vector in amazonia region. the objectives of this work were to study the periodicity of anopheles darlingi root, the host preference for peri or extra-domestic environments and the parous rate in four field sites in porto velho (ro) by human-landing. all of the anopheles specimens collected were identified, but only a. darlingi was dissected for the parous study. the results showed that human-landing colleted a total of 985 anophelines, with a. darlingi (972) being the most abundant species. female mosquitoes were more abundant at extra-domestic environments in two of the locations studied (s?o jo?o e candeias do jamari) (p < 0.05). the parous rate was 96% and no periodicity was observed for captures of females of a. darlingi in the field sites.
Page 1 /265074
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.