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I am Professor of Statistics and Econometrics at IFMG - Campus Formiga in Brazil. My research interests include Applied Statistics and Econometrics, Bayesian Methods, Statiscal Learning and Data Science.
Cement factories are the main sources of environmental pollutants among the different industrial activities, including soil contamination by potentially toxic metals. The karst region of Southeastern Brazil is known for the implementation of large cement producing facilities. This study aims to evaluate whether there is an increase in the concentration of PTM in the soil surrounding the cement plants and to estimate their harmfulness to both local human population and environment. In total, 18 soil samples were collected from the surroundings of three cement plants as well as four soil samples from areas outside the influence of cement plants and concentration of the following potentially toxic metals (PTM) were estimated: Cd, Pb, Co, Cu, Cr, Mn, Ni, and Zn. The results revealed that all PTM concentrations from cement plant surroundings were significantly higher than PTM concentrations from control areas and no PTM concentrations from CPS or CA soil samples exceeded national and global contamination thresholds. However, Igeo Index indicated low level soil contamination by Pb, Cu, and Cr, as well as high levels for Co. We could not verify significant non-carcinogenic risk to health for any soil sample, but carcinogenic risk analysis revealed different levels of carcinogenic risk among the sampled locations, for both adults and children. Our results indicate that exclusively evaluating the concentration of potentially toxic metals is not enough to verify the potential harmful effects of cement production for the surrounding population. Here we evidence that additional indices, based on both contamination indices and health risk assessments, should be considered for better evaluation of the impacts of cement production activity.
Thiago Silva; Marcos Paula; Washington Silva; Gustavo Lacorte. Deposition of Potentially Toxic Metals in the Soil from Surrounding Cement Plants in a Karst Area of Southeastern Brazil. Conservation 2021, 1, 137 -150.
AMA StyleThiago Silva, Marcos Paula, Washington Silva, Gustavo Lacorte. Deposition of Potentially Toxic Metals in the Soil from Surrounding Cement Plants in a Karst Area of Southeastern Brazil. Conservation. 2021; 1 (3):137-150.
Chicago/Turabian StyleThiago Silva; Marcos Paula; Washington Silva; Gustavo Lacorte. 2021. "Deposition of Potentially Toxic Metals in the Soil from Surrounding Cement Plants in a Karst Area of Southeastern Brazil." Conservation 1, no. 3: 137-150.
O trabalho teve como objetivo analisar a presença do viés de confirmação em gestores e contadores em um processo de tomada de decisão gerencial, bem como analisar se a forma com que as informações econômico-financeiras são apresentadas influencia o viés de confirmação desses indivíduos em suas decisões. Para atender ao objetivo da pesquisa, utilizou-se a metodologia experimental, aplicada a uma amostra de 86 contadores, 68 gestores e de 118 pessoas com atividades diversas (grupo controle). Os resultados demonstraram que a maioria dos gestores e dos contadores apresentaram viés de confirmação em processos de tomada de decisões gerenciais, que os fatores tipo (positiva ou negativa) e nível (simples ou complexa) não influenciam o viés de confirmação na tomada da decisão gerencial e que a informação negativa pode atenuar o viés de confirmação na escolha da informação mais importante.
Daniel Fonseca Costa; Francisval De Melo Carvalho; Bruno César De Melo Moreira; Washington Santos Silva. Viés de confirmação na tomada de decisão gerencial: um estudo experimental com gestores e contadores. Revista de Contabilidade e Organizações 2020, 14, e164200 -e164200.
AMA StyleDaniel Fonseca Costa, Francisval De Melo Carvalho, Bruno César De Melo Moreira, Washington Santos Silva. Viés de confirmação na tomada de decisão gerencial: um estudo experimental com gestores e contadores. Revista de Contabilidade e Organizações. 2020; 14 ():e164200-e164200.
Chicago/Turabian StyleDaniel Fonseca Costa; Francisval De Melo Carvalho; Bruno César De Melo Moreira; Washington Santos Silva. 2020. "Viés de confirmação na tomada de decisão gerencial: um estudo experimental com gestores e contadores." Revista de Contabilidade e Organizações 14, no. : e164200-e164200.
The use of system dynamics techniques to model the sales and operations planning (S&OP), associated with the economic and financial processes, is an innovative proposal. The objectives of this article are to model and simulate the S&OP process integrated with the financial management in a Brazilian lime processing industry, based on the system dynamics approach. Initially, the model was validated. Then, over twenty scenarios were simulated to assess the behavior of the system with its key factors variation. In the microenvironment scenarios, the company's internal perspective was the only element taken into account. In turn, regarding the macro environment scenarios, the basis was the projection of lime consumption related to the country's GDP. The results have genuinely contributed to the industry researched, since the lime processing industry is struggling with obtaining enough supply due to lime acquisition price fluctuations and, consequently, the oscillation of its production costs.
Nayara Teixeira Santos; Gisele Tessari Santos; Washington Santos Silva; Wanyr Romero Ferreira; Ifnmg; Ietec; Ibmec; Ifmg. A System Dynamics Model for Sales and Operations Planning. International Journal of System Dynamics Applications 2020, 9, 1 -17.
AMA StyleNayara Teixeira Santos, Gisele Tessari Santos, Washington Santos Silva, Wanyr Romero Ferreira, Ifnmg, Ietec, Ibmec, Ifmg. A System Dynamics Model for Sales and Operations Planning. International Journal of System Dynamics Applications. 2020; 9 (1):1-17.
Chicago/Turabian StyleNayara Teixeira Santos; Gisele Tessari Santos; Washington Santos Silva; Wanyr Romero Ferreira; Ifnmg; Ietec; Ibmec; Ifmg. 2020. "A System Dynamics Model for Sales and Operations Planning." International Journal of System Dynamics Applications 9, no. 1: 1-17.
Biospeckle or dynamic speckle can be used as a method for analysing activity, biologic or not, from materials illuminated with laser beam. The Spatial Temporal Speckle (STS) contains data of time information of dynamic speckle and it is used as input for many techniques allowing the analysis of the activity which is being monitored. One question that rises from the manipulation of the STS is related with the information inside it, in particular, whether it is possible to access different frequency behaviors in the time series presented in the STS pattern. This study presents the Inertia Moment, the Wavelets based Entropy and the Cross-Spectrum analysis as approaches that can be used for evaluating the STS spectral content. In a simulation, STS lines have been created based on many frequencies of the fundamental harmonic. This was done for verifying as each method acts when analysing different frequencies, varying harmonics offset and amplitude. These techniques were applied to real database, to validate their action mechanism in real samples. The results present that all techniques were able to verify the spectral content of different harmonics. Inertia Moment was more efficient on analysing high frequencies, because it is a second order moment, being able to obtain more information from high variations on activity. Entropy and Cross-Spectrum, in turn, were better on differing lower frequencies. This was attributed to the convolution proccess, which is present in both methods, filtering high frequencies. Although, any of them returned informations on both high and low frequencies at the same time, they can be used simultaneously, since Entropy and Cross-Spectrum were complementary to Inertia Moment.
C.M.B. Nobre; R.A. Braga; A.G. Costa; R.R. Cardoso; W.S. da Silva; T. Sáfadi. Biospeckle laser spectral analysis under Inertia Moment, Entropy and Cross-Spectrum methods. Optics Communications 2009, 282, 2236 -2242.
AMA StyleC.M.B. Nobre, R.A. Braga, A.G. Costa, R.R. Cardoso, W.S. da Silva, T. Sáfadi. Biospeckle laser spectral analysis under Inertia Moment, Entropy and Cross-Spectrum methods. Optics Communications. 2009; 282 (11):2236-2242.
Chicago/Turabian StyleC.M.B. Nobre; R.A. Braga; A.G. Costa; R.R. Cardoso; W.S. da Silva; T. Sáfadi. 2009. "Biospeckle laser spectral analysis under Inertia Moment, Entropy and Cross-Spectrum methods." Optics Communications 282, no. 11: 2236-2242.
The dynamic speckle analysis has been done because speckle interference began to be evaluated as an important source of information, especially those related to biological samples under laser beam. The time history speckle pattern, a THSP image, is an approach to analyze, which allows a summary to represent the activity monitored. THSP adoption has compelled the research to evaluate the information and the reliability of its inner pattern. This study presents a statistical approach to analyze the data using white noise tests and cross-spectrum analysis. The data analyzed was a set of THSP from animal sperm samples. The evaluation of white noise among lines was conducted using the Fischer test over eight THSP and the cross-spectral approach has been conducted by comparing the information in each THSP. The results presented that the THSP of the sperm did not behave as a white noise in a global evaluation, and specifically in the Gaussian white noise test over 4096 lines; only six lines presented the behavior of a white noise pattern. The strong rejection of white noise test confirms that the THSP pattern allows reliable information. The results obtained with the cross-spectral analysis presented differences between lines within the same THSP, showing that the information of an inner pattern varies in relation to space, which is against the findings in literature.
R.A. Braga; Washington Silva; T. Sáfadi; C.M.B. Nobre. Time history speckle pattern under statistical view. Optics Communications 2008, 281, 2443 -2448.
AMA StyleR.A. Braga, Washington Silva, T. Sáfadi, C.M.B. Nobre. Time history speckle pattern under statistical view. Optics Communications. 2008; 281 (9):2443-2448.
Chicago/Turabian StyleR.A. Braga; Washington Silva; T. Sáfadi; C.M.B. Nobre. 2008. "Time history speckle pattern under statistical view." Optics Communications 281, no. 9: 2443-2448.
Examinou-se o processo da volatilidade dos retornos de duas importantes commodities agrícolas brasileiras, o café e a soja, por meio de modelos da classe ARCH. Os resultados empíricos sugerem fortes sinais de persistência e assimetria na volatilidade de ambas as séries. Além disso, os resultados sugerem que a implementação de políticas que criem, facilitem o acesso e estimulem a utilização de instrumentos de hedging baseados no mercado podem ser estratégias adequadas para tais setores diante da persistência de choques e volatilidade pronunciadas constatadas para os retornos destas commodities
Washington Santos Da Silva; Thelma Sáfadi; Luiz Gonzaga De Castro Júnior. Uma análise empírica da volatilidade do retorno de commodities agrícolas utilizando modelos ARCH: os casos do café e da soja. Revista de Economia e Sociologia Rural 2005, 43, 119 -134.
AMA StyleWashington Santos Da Silva, Thelma Sáfadi, Luiz Gonzaga De Castro Júnior. Uma análise empírica da volatilidade do retorno de commodities agrícolas utilizando modelos ARCH: os casos do café e da soja. Revista de Economia e Sociologia Rural. 2005; 43 (1):119-134.
Chicago/Turabian StyleWashington Santos Da Silva; Thelma Sáfadi; Luiz Gonzaga De Castro Júnior. 2005. "Uma análise empírica da volatilidade do retorno de commodities agrícolas utilizando modelos ARCH: os casos do café e da soja." Revista de Economia e Sociologia Rural 43, no. 1: 119-134.