Seleção de modelos de variabilidade espacial para elaboração de mapas temáticos de atributos físicos do solo e produtividade da soja

Pesquisas sobre a variabilidade espacial dos atributos do solo que influenciam a produtividade são de uma grande importância para o desenvolvimento de novas técnicas que beneficiam a agricultura. A variabilidade desses atributos pode ser avaliada por técnicas de geoestatística e auxiliar no mapeamento e manejo do solo. Este trabalho teve por objetivo avaliar a qualidade do ajuste dos modelos teóricos espaciais segundo o Critério de Informação de Akaike, de Filliben, de Validação Cruzada e o valor máximo do logaritmo da função verossimilhança, de dados da umidade do solo, da densidade do solo e da resistência do solo à penetração, nas camadas de 0 a 0,1, 0,1 a 0,2 e 0,2 a 0,3 m, e de produtividade da soja do ano agrícola 2004-2005. Os parâmetros dos modelos de variabilidade espacial foram estimados por meio dos métodos de mínimos quadrados ordinários, mínimos quadrados ponderados e máxima verossimilhança. A pesquisa foi desenvolvida em uma área de 57 ha de um Latossolo Vermelho distroférrico, utilizando-se uma malha de 75 x 75 m georreferenciada. Concluiu-se que, dos métodos de avaliação de ajustes estudados, o da Validação Cruzada foi o mais adequado para escolha do melhor ajuste do modelo de variabilidade espacial; conseqüentemente têm-se mapas temáticos mais acurados.

Root abundance of maize in conventionally-tilled and zero-tilled soils of Argentina

Maize root growth is negatively affected by compacted layers in the surface (e.g. agricultural traffic) and subsoil layers (e.g. claypans). Both kinds of soil mechanical impedances often coexist in maize fields, but the combined effects on root growth have seldom been studied. Soil physical properties and maize root abundance were determined in three different soils of the Rolling Pampa of Argentina, in conventionally-tilled (CT) and zero-tilled (ZT) fields cultivated with maize. In the soil with a light Bt horizon (loamy Typic Argiudoll, Chivilcoy site), induced plough pans were detected in CT plots at a depth of 0-0.12 m through significant increases in bulk density (1.15 to 1.27 Mg m-3) and cone (tip angle of 60 º) penetrometer resistance (7.18 to 9.37 MPa in summer from ZT to CT, respectively). This caused a reduction in maize root abundance of 40-80 % in CT compared to ZT plots below the induced pans. Two of the studied soils had hard-structured Bt horizons (clay pans), but in only one of them (silty clay loam Abruptic Argiudoll, Villa Lía site) the expected penetrometer resistance increases (up to 9 MPa) were observed with depth. In the other clay pan soil (silty clay loam Vertic Argiudoll, Pérez Millán site), penetrometer resistance did not increase with depth but reached 14.5 MPa at 0.075 and 0.2 m depth in CT and ZT plots, respectively. However, maize root abundance was stratified in the first 0.2 m at the Villa Lía and Pérez Millán sites. There, the hard Bt horizons did not represent an absolute but a relative mechanical impedance to maize roots, by the observed root clumping through desiccation cracks.

Anisotropia no estudo da variabilidade espacial de algumas variáveis químicas do solo

No estudo do mapeamento da fertilidade do solo, pelas técnicas de geoestatística, algumas características estruturais da variabilidade espacial devem ser consideradas, tais como continuidade espacial e ausência de anisotropia. Neste contexto, o presente trabalho apresenta uma análise da anisotropia no estudo da variabilidade espacial das variáveis químicas do solo: ferro (Fe), acidez potencial (H + Al), matéria orgânica (MO) e Mn, de um conjunto de dados de 128 parcelas sem manejo químico localizado, espacialmente referenciados, estudados entre 1998 e 2002, em um Latossolo Vermelho distroférrico, em Cascavel-PR. A identificação da anisotropia foi realizada por meio da construção de semivariogramas direcionais com modelos ajustados, e a correção da anisotropia realizou-se por meio de transformações lineares e de modelos combinados. Em seguida, utilizou-se um modelo ajustado ao semivariograma omnidirecional para construção de mapas temáticos de variabilidade das variáveis estudadas. Observou-se a existência de anisotropia geométrica para a variável H + Al. Já as variáveis MO, Mn e Fe mostraram a presença de anisotropia combinada, sendo corrigida inicialmente a anisotropia geométrica e, posteriormente, a anisotropia zonal. Por meio do estudo da anisotropia, foi possível eliminar as direções privilegiadas, melhorando assim o ajuste dos semivariogramas e produzindo mapas temáticos das variáveis químicas estudadas com maior acurácia.

Diagnostic techniques applied in geostatistics for agricultural data analysis

The structural modeling of spatial dependence, using a geostatistical approach, is an indispensable tool to determine parameters that define this structure, applied on interpolation of values at unsampled points by kriging techniques. However, the estimation of parameters can be greatly affected by the presence of atypical observations in sampled data. The purpose of this study was to use diagnostic techniques in Gaussian spatial linear models in geostatistics to evaluate the sensitivity of maximum likelihood and restrict maximum likelihood estimators to small perturbations in these data. For this purpose, studies with simulated and experimental data were conducted. Results with simulated data showed that the diagnostic techniques were efficient to identify the perturbation in data. The results with real data indicated that atypical values among the sampled data may have a strong influence on thematic maps, thus changing the spatial dependence structure. The application of diagnostic techniques should be part of any geostatistical analysis, to ensure a better quality of the information from thematic maps.

Pedotransfer functions to estimate proctor test parameters under different tillage systems

The Proctor test is time-consuming and requires sampling of several kilograms of soil. Proctor test parameters were predicted in Mollisols, Entisols and Vertisols of the Pampean region of Argentina under different management systems. They were estimated from a minimum number of readily available soil properties (soil texture, total organic C) and management (training data set; n = 73). The results were used to generate a soil compaction susceptibility model, which was subsequently validated using a second group of independent data (test data set; n = 24). Soil maximum bulk density was estimated as follows: Maximum bulk density (Mg m-3) = 1.4756 - 0.00599 total organic C (g kg-1) + 0.0000275 sand (g kg-1) + 0.0539 management. Management was equal to 0 for uncropped and untilled soils and 1 for conventionally tilled soils. The established models predicted the Proctor test parameters reasonably well, based on readily available soil properties. Tillage systems induced changes in the maximum bulk density regardless of total organic matter content or soil texture. The lower maximum apparent bulk density values under no-tillage require a revision of the relative compaction thresholds for different no-tillage crops.

Selecting statistical models to study the relationship between soybean yield and soil physical properties

Statistical models allow the representation of data sets and the estimation and/or prediction of the behavior of a given variable through its interaction with the other variables involved in a phenomenon. Among other different statistical models, are the autoregressive state-space models (ARSS) and the linear regression models (LR), which allow the quantification of the relationships among soil-plant-atmosphere system variables. To compare the quality of the ARSS and LR models for the modeling of the relationships between soybean yield and soil physical properties, Akaike's Information Criterion, which provides a coefficient for the selection of the best model, was used in this study. The data sets were sampled in a Rhodic Acrudox soil, along a spatial transect with 84 points spaced 3 m apart. At each sampling point, soybean samples were collected for yield quantification. At the same site, soil penetration resistance was also measured and soil samples were collected to measure soil bulk density in the 0-0.10 m and 0.10-0.20 m layers. Results showed autocorrelation and a cross correlation structure of soybean yield and soil penetration resistance data. Soil bulk density data, however, were only autocorrelated in the 0-0.10 m layer and not cross correlated with soybean yield. The results showed the higher efficiency of the autoregressive space-state models in relation to the equivalent simple and multiple linear regression models using Akaike's Information Criterion. The resulting values were comparatively lower than the values obtained by the regression models, for all combinations of explanatory variables.

Local influence for spatial analysis of soil physical properties and soybean yield using student's t-distribution

The modeling and estimation of the parameters that define the spatial dependence structure of a regionalized variable by geostatistical methods are fundamental, since these parameters, underlying the kriging of unsampled points, allow the construction of thematic maps. One or more atypical observations in the sample data can affect the estimation of these parameters. Thus, the assessment of the combined influence of these observations by the analysis of Local Influence is essential. The purpose of this paper was to propose local influence analysis methods for the regionalized variable, given that it has n-variate Student's t-distribution, and compare it with the analysis of local influence when the same regionalized variable has n-variate normal distribution. These local influence analysis methods were applied to soil physical properties and soybean yield data of an experiment carried out in a 56.68 ha commercial field in western Paraná, Brazil. Results showed that influential values are efficiently determined with n-variate Student's t-distribution.

Nonrelativistic bound states at finite temperature. II. Muonic hydrogen

We illustrate how to apply modern effective field-theory techniques and dimensional regularization to factorize the various scales, which appear in QED bound states at finite temperature. We focus here on the muonic hydrogen atom. Vacuum polarization effects make the physics of this atom at finite temperature very close to that of heavy quarkonium states. We comment on the implications of our results for these states in the quark gluon plasma. In particular, we estimate the effects of a finite-charm quark mass in the dissociation temperature of bottomonium.

N2O emissions from a cultivated mollisol: optimal time of day for sampling and the role of soil temperature

The correct use of closed field chambers to determine N2O emissions requires defining the time of day that best represents the daily mean N2O flux. A short-term field experiment was carried out on a Mollisol soil, on which annual crops were grown under no-till management in the Pampa Ondulada of Argentina. The N2O emission rates were measured every 3 h for three consecutive days. Fluxes ranged from 62.58 to 145.99 ∝g N-N2O m-2 h-1 (average of five field chambers) and were negatively related (R² = 0.34, p < 0.01) to topsoil temperature (14 - 20 ºC). N2O emission rates measured between 9:00 and 12:00 am presented a high relationship to daily mean N2O flux (R² = 0.87, p < 0.01), showing that, in the study region, sampling in the mornings is preferable for GHG.

Financial crisis: theory and practice

In the last 50 years, we have had approximately 40 events with characteristics related to financial crisis. The most severe crisis was in 1929, when the financial markets plummet and the US gross domestic product decline in more than 30 percent. Recently some years ago, a new crisis developed in the United States, but instantly caused consequences and effects in the rest of the world.This new economic and financial crisis has increased the interest and motivation for the academic community, professors and researchers, to understand the causes and effects of the crisis, to learn from it. This is the one of the main reasons for the compilation of this book, which begins with a meeting of a group of IAFI researchers from the University of Barcelona, where researchers form Mexico and Spain, explain causes and consequences of the crisis of 2007.For that reason, we believed this set of chapters related to methodologies, applications and theories, would conveniently explained the characteristics and events of the past and future financial crisisThis book consists in 3 main sections, the first one called "State of the Art and current situation", the second named "Econometric applications to estimate crisis time periods" , and the third one "Solutions to diminish the effects of the crisis". The first section explains the current point of view of many research papers related to financial crisis, it has 2 chapters. In the first one, it describe and analyzes the models that historically have been used to explain financial crisis, furthermore, it proposes to used alternative methodologies such as Fuzzy Cognitive Maps. On the other hand , Chapter 2 , explains the characteristics and details of the 2007 crisis from the US perspective and its comparison to 1929 crisis, presenting some effects in Mexico and Latin America.The second section presents two econometric applications to estimate possible crisis periods. For this matter, Chapter 3, studies 3 Latin-American countries: Argentina, Brazil and Peru in the 1994 crisis and estimates the multifractal characteristics to identify financial and economic distress.Chapter 4 explains the crisis situations in Argentina (2001), Mexico (1994) and the recent one in the United States (2007) and its effects in other countries through a financial series methodology related to the stock market.The last section shows an alternative to prevent the effects of the crisis. The first chapter explains the financial stability effects through the financial system regulation and some globalization standards. Chapter 6, study the benefits of the Investor activism and a way to protect personal and national wealth to face the financial crisis risks.

Low-dose theophylline enhances the anti-inflammatory effects of steroids during exacerbations of chronic obstructive pulmonary disease

ABSTRACT Background: Chronic obstructive pulmonary disease (COPD) is characterised by an abnormal inflammatory response mainly to cigarette smoke that flares up during exacerbations of the disease (ECOPD). Reduced activity of histone deacetylases (HDAC) contributes to enhanced inflammation in stable COPD. It was hypothesised that HDAC activity is further reduced during ECOPD and that theophylline, an HDAC activator, potentiates the antiinflammatory effect of steroids in these patients. A study was performed to investigate HDAC activity during ECOPD and the effects of theophylline on the anti-inflammatory effects of steroids in a randomised single-blind controlled study. Methods: 35 patients hospitalised with ECOPD and treated according to international guidelines (including systemic steroids) were randomised to receive or not to receive low-dose oral theophylline (100 mg twice daily). Before treatment and 3 months after discharge, HDAC and nuclear factor-kB (NF-kB) activity in sputum macrophages, the concentration of nitric oxide in exhaled air (eNO) and total antioxidant status (TAS), tumour necrosis factor a (TNFa), interleukin (IL)-6 and IL8 levels in sputum supernatants were measured. Results: Patients receiving standard therapy showed decreased NF-kB activity, eNO concentration and sputum levels of TNFa, IL6 and IL8, as well as increased TAS during recovery of ECOPD, but HDAC activity did not change. The addition of low-dose theophylline increased HDAC activity and further reduced IL8 and TNFa concentrations. Conclusions: During ECOPD, low-dose theophylline increases HDAC activity and improves the anti-inflammatory effects of steroids.

About IPERS, October 2011

It’s never too early to start thinking about retirement. Regardless of your retirement plans or anticipated retirement age, you want a financially secure retirement. IPERS provides the security you need through guaranteed benefits. With IPERS, unlike other retirement plans, benefits aren’t tied to the performance of the stock market and you don’t need to be an experienced investor to make your retirement dreams a reality. Remember, your IPERS benefits are only one part of your overall retirement savings. Your total retirement income will come from a combination of your IPERS benefits, social security, personal savings, and any other retirement plan benefits.

Un mosaico con tema de muralla en Tarragona

En los primeros días de octubre de 1973, al tener noticia del derribo de la casa nº19 de la calle Gobernador González, de ,Tarragona, recabamos la oportuna autorización al nuevo propietario del inmueble, don Angel Molinero Sisamón, para poder recuperar el mosaico allí existente. El mosaico estaba visible en parte, ya de antiguo, en un pequeño patio de luces de la casa derribada, por lo que se presentaba ahora la ocasión de excavarlo y extraerlo en su totalidad (lám. J, a). La extracción había que realizarla con relativa rapidez para no entorpecer los trabajos preparatorios de la nueva construcción, por lo que pedimos la colaboración de parte de la brigada del Patrimonio Artístico Nacional, que en esas fechas trabajaban en la Plaza del Rey, además del capataz de las excavaciones de Els Munts, práctico ya en el arranque de mosaicos. Nuestra labor no se limitó a salvar el mosaico sino que aprovecharnos la oportunidad para estudiar el solar resultante del derribo de la casa y del jardín situado al norte¡ de la misma. A este fin realizamos una zanja de 5 metros al norte del mosaico hasta llegar a un pozo negro y efectuamos cuatro catas de sondeo de 1,50 por 1,50 metros dentro del área del antiguo jardín. La zanja dio unos resultados positivos, aunque modestos, y no así las catas que nos patentizaron la falta absoluta de restos arqueológicos de alguna importancia en toda aquella zona. La parte situada al sur del mosaico ya había sido rebajada antiguamente hasta el nivel de la calle.

Aspectos que interferem na construção da acessibilidade em bibliotecas universitárias

Apresenta-se a evolução do conceito da acessibilidade, inicialmente associado apenas ao projeto livre de barreiras, para o que é hoje conhecido como desenho para todos, envolvendo aspectos tanto do mundo físico como do mundo digital. Discute-se a importância de as bibliotecas universitárias adotarem critérios de acessibilidade, contribuindo para isso o espaço digital. A partir do estudo de caso feito em uma universidade federal brasileira específica, focado nos aspectos de acesso à informação e comunicação e aspectos atitudinais, são elaboradas propostas de melhorias para as condições de acessibilidade em bibliotecas universitárias.