Igor Pereira - Academia.edu (original) (raw)

Papers by Igor Pereira

Research paper thumbnail of Impacto econômico da execução do projeto estrutural em uma residência localizada no bairro Tarumã em Manaus/Amazonas

Brazilian Journal of Development

O projeto estrutural na execução de obras influencia diretamente a eficácia construtiva final, ta... more O projeto estrutural na execução de obras influencia diretamente a eficácia construtiva final, tanto em obras de baixa quanto de alta complexidade. Através de dimensionamentos estruturais é possível obter dados específicos relevantes ao levantamento de materiais, decisões de métodos construtivos, técnicas de planejamento e otimização de cronograma, além de corroborar no efetivo orçamento de uma obra, controle de riscos e patologias. Nesse contexto, o trabalho tem como objetivo estudar o impacto econômico estrutural em uma obra residencial no localizada no bairro Tarumã, em Manaus/Amazonas. Foi verificado através das planilhas de custos e análises de dados, que os serviços da estrutura possuem significante diferença entre o custo estimado e executado. Contudo, as etapas finalizadas demonstraram que a construção da residência ocorreu de maneira satisfatória.

Research paper thumbnail of Estudo do processo construtivo de um protótipo que servirá como base para uma residência unifamiliar utilizando painel monolítico em Manaus/Amazonas

Brazilian Journal of Development

As tecnologias construtivas da engenharia avançam em diversos segmentos simultaneamente, o que co... more As tecnologias construtivas da engenharia avançam em diversos segmentos simultaneamente, o que contribui para a aplicação de sistemas construtivos diferentes dos convencionais, entretanto com boa eficiência competitiva ao mercado. Dessa forma, o sistema construtivo monolítico com placas de poliestireno expandido (EPS) é um sistema estruturado por duas malhas de aço eletrossoldadas entre si, em sua maioria com fundação de lajes de concreto, sem pilares ou vigas em até dois pavimentos, o que garante rapidez na execução e economia de custo. Esse artigo, portanto, demonstra o processo construtivo de um protótipo que servirá como base para uma residência unifamiliar usando painel monolítico de EPS, em Manaus/Amazonas. A confecção do protótipo de poliestireno expandido teve duração de dois dias enxutos dividido em etapas de execução e após a conclusão dos serviços o protótipo mostrou-se aplicável e eficaz ao que se propõe um sistema monolítico.

Research paper thumbnail of Análise do processo elétrico industrializado de um edifício em Manaus / Analysis of the industrialized electrical process of a building in Manaus

Brazilian Journal of Development

A industrialização no setor da Construção Civil está evoluindo nas últimas décadas, devido a comp... more A industrialização no setor da Construção Civil está evoluindo nas últimas décadas, devido a competitividade do mercado entre as empresas, dessa forma, os aprimoramentos dos métodos construtivos estão sendo cada vez mais estudados, fazendo com que a busca por otimização, produtividade e diminuição de desperdícios de materiais alavanquem na atualidade. Através da literatura, pesquisa bibliográfica e estudo de caso, foi feito o acompanhamento da produtividade desse sistema em um empreendimento de grande porte. Sendo assim, o objetivo deste artigo é conhecer o desenvolvimento e o processo de fabricação, entendendo o método construtivo da Rede Elétrica Otimizada, a qual veio para garantir a diminuição de tempo na entrega de obras multifamiliares. Para oferecer embasamento teórico no estudo em questão, foi realizado o levantamento de todo o material didático necessário através da pesquisa bibliográfica, apresentando conceitos de diferentes autores, possibilitando assim o comparativo e um...

Research paper thumbnail of Are the Liabilities of Newness and Smallness the Same for Male and Female Informal Entrepreneurs? Evidence from Brazil

Entrepreneurship Research Journal, 2020

Though challenges to female entrepreneurship are widely acknowledged in the settings of developed... more Though challenges to female entrepreneurship are widely acknowledged in the settings of developed countries or the context of formal firms, the challenges faced by female informal entrepreneurs in developing markets are less explored. Based on the liabilities of newness and smallness framework in organizational ecology, we draw on a sample of 2562 Brazilian informal firms, to examine the unique differences in the experience of newness and smallness between male and female informal entrepreneurs. With increasing firm age, female informal entrepreneurs realized lower firm revenues (inverted-U), however, the firm age and firm revenue association are linear for males. Informal firm performance did not vary by size between male and female informal entrepreneurs. The distinctive differences in firm revenues for male and female entrepreneurs have implications for informal entrepreneurship.

Research paper thumbnail of Closed versus open reduction of facial fractures in children and adolescents: A systematic review and meta-analysis

Journal of Clinical and Experimental Dentistry, 2021

Research paper thumbnail of Application-Level Load Balancing for Reactive Wireless Sensor Networks: An Approach Based on Constraint Optimization Problems

Intelligent Systems, 2020

As Wireless Sensor Networks-WSNs are being used more and more in applications with high demand fo... more As Wireless Sensor Networks-WSNs are being used more and more in applications with high demand for the processing of videos and images, the processing load of the nodes also must be considered by energy-saving strategies. Usually, these strategies focused only on communication. The overloading of nodes can result in a degraded performance regarding the network lifetime and availability of the provided services. A few algorithms, based on heuristics, have been proposed in the literature to balance the load at the application level. These algorithms drawnback are the lack of quality assurance. Thus, this work presents a novel semi-distributed solution, applying techniques to solve Constraint Optimization Problem-COP on the load balancing in a WSN. Our approach guarantee that all events are processed during the lifetime of the network and that there is a fixed number of exchanged messages per event, only reducing the lifetime of the network by an estimable time. Experimental results pointed out that the proposed approach allows the network, while alive, to sense all happened events each day, and its performance is better than the one achieved by the state-of-the-art for lower density networks.

Research paper thumbnail of The relation between public assistance and self-employment in census tracts: a long-term perspective

Journal of Evolutionary Economics, 2021

We present evidence on the long-term relationship between the breadth (the proportion of househol... more We present evidence on the long-term relationship between the breadth (the proportion of households) and depth (the amount per household) of public assistance and the prevalence of self-employment in US neighbourhoods. The analysis of decennial data of 71,437 census tracts over four decades (1970 to 2000) shows that the poverty ratio lowers self-employment, and that breadth (but not depth) of public assistance mitigates the negative relationship between the poverty ratio and self-employment. The results are robust to alternate model specifications and are informative about the distributional effects of welfare spendings.

Research paper thumbnail of Impact of the COVID-19 pandemic on the hours lost by self-employed racial minorities: evidence from Brazil

Small Business Economics, 2021

month. The disproportionate loss of work hours by the self-employed from racial minority groups d... more month. The disproportionate loss of work hours by the self-employed from racial minority groups during the COVID-19 pandemic in a developing country context calls for a closer examination and assessment of the long-term impact of COVID-19 on racial minorities. Plain English Summary Large-scale evidence from Brazil: racial minorities lost more hours per month than other groups during the COVID-19 pandemic. Racial minorities face systemic discrimination in setting up and developing their businesses, especially in developing countries. We test whether during the COVID-19 pandemic self-employed racial minorities in Brazil lost more hours of work relative to employed racial minorities. We create a matched sample of employed and self-employed individuals based on age, sex, education categories, COVID-19 self-reported symptom index, income deciles, house ownership categories, week of the interview, state of the interview, and industry. We find that across racial minority groups, the hours lost by the self-employed were substantive during the pandemic, signaling that Brazilian policymakers should pay greater attention to the relief funds allocated to and policies geared towards self-employed racial minorities.

Research paper thumbnail of Determining Methamphetamine in Urine by Molecularly Imprinted Polymer Assisted Paper Spray Ionization Mass Spectrometry

Journal of the Brazilian Chemical Society, 2021

The usefulness of molecularly imprinted polymer assisted paper spray ionization mass spectrometry... more The usefulness of molecularly imprinted polymer assisted paper spray ionization mass spectrometry (MIP-PSI-MS) for the determination of methamphetamine in urine has been demonstrated. MIP-PSI-MS is a method in which a MIP is synthesized on the surface of a paper, producing a chemically selective paper surface with molecular recognition sites for a target analyte. The analyte is extracted by the MIP substrate, which is posteriorly used for conventional PSI-MS analysis. As methamphetamine is one of the most widely used drugs of abuse in the world, it was selected to be studied in synthetic urine by the MIP-PSI-MS method. Methamphetamine was detected at higher ion signals compared to other different drugs, such as lysergic acid diethylamide (LSD) and cocaine, suggesting that MIP-PSI-MS has a chemical affinity for methamphetamine. In experiments to validate the method, a linear calibration curve was achieved with R-squared (R 2) > 0.99. Limit of detection (LOD) and limit of quantification (LOQ) were determined to be 0.8 and 2.8 µg L-1 , respectively. Precision (relative standard deviation) and accuracy (relative error) were less than 10%, and the recoveries were close to 100%. The matrix effect was below 10%. These data demonstrate the possibility of using MIP-PSI-MS as an analytical tool for a specific/ selective analysis of methamphetamine in forensic sciences.

Research paper thumbnail of Paper Spray Ionization Mass Spectrometry as a Potential Tool for Early Diagnosis of Cervical Cancer

Research paper thumbnail of Decentralized Governance of Digital Platforms

Journal of Management, 2020

Over the past decade, the rise of blockchain technology has led to the emergence of a growing num... more Over the past decade, the rise of blockchain technology has led to the emergence of a growing number of decentralized platforms that are governed less by platform owners and more through community efforts. The emergence of blockchain platforms offers a unique opportunity to examine alternative structures for platform governance and to develop a theory around the value of centralized, semi-decentralized, and decentralized governance. Drawing on mechanism design theory, we evaluate the tradeoffs between centralization and decentralization and hypothesize semi-decentralization as a higher performing governance structure. Empirical evidence from the blockchain industry shows that decentralization has an inverted U-shaped relationship with platforms’ market capitalization, developer attention, and development activity. We further examine factors driving the decentralization of platform governance and find that digital platforms of the infrastructure layer—relative to those of the applica...

Research paper thumbnail of Efeito Da Adubação Nitrogenada Em Cobertura Na Severidade Da Ferrugem Comum Do Milho

JOURNAL OF NEOTROPICAL AGRICULTURE, 2017

A adubação nitrogenada pode interferir positivamente ou negativamente na intensidade de diversas ... more A adubação nitrogenada pode interferir positivamente ou negativamente na intensidade de diversas doenças das plantas. Neste contexto, este estudo objetivou avaliar o efeito da aplicação de doses de nitrogênio em cobertura na severidade da ferrugem comum do milho (Puccinia sorghi). O experimento foi instalado na Fazenda Experimental da EPAMIG, em Prudente de Morais (MG), utilizando-se o híbrido de milho-verde AG 4051. O delineamento experimental adotado foi de blocos ao acaso com cinco tratamentos e três repetições. Os tratamentos constituíram da aplicação de cinco doses de N (0, 60, 120, 180 e 240 kg ha-1) na forma de ureia em cobertura. Foram realizadas cinco avaliações (em intervalo semanal) da severidade da doença em 3 folhas marcadas (2 acima e 1 abaixo da espiga) em seis plantas por parcela e ao final, calculou-se a área abaixo da curva de progresso da doença (AACPD). A equação polinomial quadrática (y = 707,9 + 3,34x – 0,0107x2) foi a que melhor se ajustou (R2 = 0,86). A sever...

Research paper thumbnail of Substratos Orgânicos Na Produção De Mudas De Cafeeiro Em Tubetes

REVISTA DE AGRICULTURA NEOTROPICAL, 2017

Considerando-se a importância das mudas na formação de lavoura cafeeira (Coffea arabica L.), obje... more Considerando-se a importância das mudas na formação de lavoura cafeeira (Coffea arabica L.), objetivou-se avaliar características agronômicas e índices de qualidade de mudas do cafeeiro cv. Topázio MG 1190, produzidos em tubetes com a utilização de diferentes proporções de materiais orgânicos no substrato comercial. O experimento foi em delineamento experimental em blocos casualizados, dispostos em esquema fatorial 4 x 4, sendo quatro fontes de esterco: bovino, cama de frango, coelho e suíno em quatro proporções (0, 20, 40 e 60%) no substrato comercial Bioplant® com quatro repetições. As parcelas foram formadas por sete plantas dispostas em tubetes com volume de 180 mL. Foram avaliadas as características agronômicas: altura da planta, número de par de folhas, área foliar, diâmetro de caule, massa seca da parte aérea, massa seca da raiz, relação altura da planta e diâmetro de caule, relação massa seca de parte aérea e massa seca da raiz e índice de qualidade de Dickson (IQD). Os res...

Research paper thumbnail of Determinação De Designer Drugs Em Saliva Por Paper Spray Mass Spectrometry

Química Nova, 2019

Recebido em 23/01/2019; aceito em 06/05/2019; publicado na web em 27/06/2019 DETERMINATION OF DES... more Recebido em 23/01/2019; aceito em 06/05/2019; publicado na web em 27/06/2019 DETERMINATION OF DESIGNER DRUGS IN SALIVA BY PAPER SPRAY MASS SPECTROMETRY. Determination of two drugs of abuse in saliva has been performed by Paper Spray Ionization Mass Spectrometry (PSI-MS) using a Molecularly Imprinted Polymer (MIP) coated paper as substrate. The method has been optimized for quantification of 3,4-methylenedioxy-N-methylamphetamine (MDMA) and methamphetamine, 3,4-methylenedioxyamphetamine (MDA) from synthetic saliva samples. Rapid analysis (~ 1 min) of designer drugs in saliva is demonstrated using MIP-PSI-MS. Both precursor ions of MDMA and MDA were confirmed by tandem mass spectrometry (MS/MS) experiments by elucidating the fragmentation patterns formed via collisioninduced dissociation (CID). The MIP-PSI-MS method showed greater selectivity for MDMA and MDA in comparison with other analytes. Signal intensity ratios of the most important transitions for MDMA (194 → 163) and MDA (180 → 163) were found linear (R > 0,99) in the range 25-500 µg L-1. The LOD and LOQ for MDMA were 1.11 µg L-1 and 18.73 µg L-1 , respectively, and for MDA were 3.42 µg L-1 and 21.66 µg L-1 , respectively. The precision and accuracy values were determined below 4%, and the recoveries about 100%, without pre-concentration/enrichment or separation steps. The MIP-PSI-MS method displays the potential for rapid screening for selective quantitative determination of illicit drugs in saliva samples.

Research paper thumbnail of INTERAÇÃO Allium cepa X Stemphylium spp ASSOCIADOS AO USO DO INDUTOR DE RESISTÊNCIA ACIBENZOLAR S-METIL

Agrarian Academy, 2018

RESUMO Diversos agentes vêm sendo estudados como indutores de respostas de defesa em plantas. Ent... more RESUMO Diversos agentes vêm sendo estudados como indutores de respostas de defesa em plantas. Entre esses destaca-se o Acibenzolar S-metil (ASM) que age induzindo a expressão de proteínas PR e enzimas relacionadas com a síntese de lignina como as peroxidases bem como fitoalexinas que são compostos tóxicos aos patógenos, possibilitando aumento da resistência das plantas. Desse modo, objetivou-se estudar o efeito do ASM na manifestação de respostas de defesa a Stemphylium spp. em mudas de cebola, por meio da determinação da atividade da peroxidase. O delineamento experimental utilizado foi o inteiramente casualizado no esquema de parcelas subdivididas no tempo. Foram realizados cinco tratamentos, quatro avaliações no intervalo de 1, 24, 48 e 72 horas após a inoculação do patógeno e quatro repetições. Os tratamentos foram T1-Testemunha absoluta, T2-com ASM e sem patógeno, T3-sem ASM e com patógeno, T4-com o patógeno e ASM 0,2 mg/mL e T5-com patógeno e ASM 0,4 mg/mL. Os valores da atividade da enzima peroxidase foram menores, durante os períodos de avaliação, nos tratamentos com ASM ou Stemphylium spp. em comparação com a testemunha. Nos tratamentos com a inoculação do patógeno, independente da presença do ASM a atividade de peroxidase diminuiu ao longo do período de avaliação. Os resultados sugerem que a presença do patógeno é mais efetiva em induzir alterações na atividade enzimática de peroxidase que o ASM, porém somente o comportamento da peroxidase não foi suficiente para entender o seu papel na defesa do vegetal. PALAVRAS-CHAVE: Bion ® , cebola, peroxidase.

Research paper thumbnail of Surgical treatment of Adenomatoid Odontogenic Tumor: A 5-year follow-up

Revista Portuguesa de Estomatologia, Medicina Dentária e Cirurgia Maxilofacial, 2017

Adenomatoid odontogenic tumor (AOT) is a rare odontogenic tumor with limited growth and usually a... more Adenomatoid odontogenic tumor (AOT) is a rare odontogenic tumor with limited growth and usually associated with an unerupted permanent tooth. It is a benign lesion, with a low rate of recurrence after surgical treatment. This is a case report of an 11-year-old female with an asymptomatic tumor growth on the maxilla and palatal displacement of the lateral incisor. A unilocular lesion surrounding the coronal impacted right upper canine and the displacement of premolars were observed radiographically. After incisional biopsy, the tumor was diagnosed as AOT. The enucleation of the lesion and the removal of the impacted canine was performed. Four months later, the patient had not shown any signs of recurrence and was referred for orthodontic treatment. New surgical procedure was performed to remove the gums that covered the premolars to promote their eruption. Five years later, the premolars are in position in the dental arch and there are no signs of recurrence of the lesion.

Research paper thumbnail of Taking advantage of an unerupted third molar: a case report

Dental Press Journal of Orthodontics, 2017

Introduction: Treatments with dental surgery seek to displace tooth to the correct position withi... more Introduction: Treatments with dental surgery seek to displace tooth to the correct position within the dental arch. Objective: To report a clinical case that took advantage of an unerupted third molar. Case history: A male patient, 18 years of age, was referred by his dentist to evaluate the third molars. The clinical exam revealed no visible lower third molars. The computed tomography (CT) exam showed the presence of a supernumerary tooth in the region of the mandibular ramus, on the left side, and impaction of the third molar, which was causing root resorption on the second molar, thus making it impossible to remain in the buccal cavity. The preferred option, therefore, was to remove both second molar and the supernumerary tooth, in addition to attaching a device to the third molar during surgery for further traction. Results: After 12 months, the third molar reached the proper position. Conclusion: When a mandibular second permanent molar shows an atypical root resorption, an imp...

Research paper thumbnail of Laser Ablation Electrospray Ionization Mass Spectrometry with Ion Mobility Separation Reveals Metabolites in the Symbiotic Interactions of Soybean Roots and Rhizobia

The Plant journal : for cell and molecular biology, Jan 10, 2017

Technologies enabling in situ metabolic profiling of living plant systems are invaluable for unde... more Technologies enabling in situ metabolic profiling of living plant systems are invaluable for understanding physiological processes and could be used for rapid phenotypic screening (e.g., to produce plants with superior biological nitrogen fixing ability). The symbiotic interaction between legumes and nitrogen-fixing soil bacteria results in a specialized plant organ (i.e., root nodule) where the exchange of nutrients between host and endosymbiont occurs. Laser ablation electrospray ionization mass spectrometry (LAESI-MS) is a method that can be performed under ambient conditions requiring minimal sample preparation. Here, we employed LAESI-MS to explore the well-characterized symbiosis between soybean (Glycine max L. Merr.) and its compatible symbiont, Bradyrhizobium japonicum. The utilization of ion mobility separation (IMS) improved the molecular coverage, selectivity, and identification of the detected biomolecules. Specifically, incorporation of IMS resulted in an increase of 15...

Research paper thumbnail of Differentiation of Toxic and Non-Toxic Leaves of Jatropha curcas L. Genotypes by Leaf Spray Mass Spectrometry

Journal of the Brazilian Chemical Society, 2016

Jatropha curcas L. is an oil crop that has been studied as a potential source of biodiesel. A hig... more Jatropha curcas L. is an oil crop that has been studied as a potential source of biodiesel. A high protein pie is produced as a byproduct of the biodiesel production, which could be used as animal feed. However, the pie has toxic compounds, as phorbol esters and other toxins, which prevents the use as animal feed. For this reason, Embrapa (Brazilian Agricultural Research Corporation) has been working in genetic breeding to develop non-toxic J. curcas genotypes. To evaluate this process, a simple and fast analytical technique was employed to obtain responses in a short time. Leaf spray (LS) is a recent ambient ionization mass spectrometry technique in which the sample itself serves as support and ion source. Here, toxic and non-toxic J. curcas leaves were differentiated by LS using a linear ion trap mass spectrometer and partial least squares discriminant analysis (PLS-DA) model chemometrics. It was possible to differentiate toxic and non-toxic leaves and to identify the m/z values that contribute to discrimination between the groups.

Research paper thumbnail of Repositório Digital: instrumento de aprendizagem na Educação Profissional

Anais do XXII Workshop de Informática na Escola (WIE 2016), 2016

Este trabalho tem o objetivo de apresentar o desenvolvimento e implementação de um repositório di... more Este trabalho tem o objetivo de apresentar o desenvolvimento e implementação de um repositório digital e a simultânea criação de um website. Concebido por alunos do curso Técnico em Informática para Internet integrado ao ensino médio, esse instrumento de aprendizagem para a Educação Profissional foi dividido em duas etapas: o desenvolvimento do banco de dados e a implementação do website, ambos utilizando linguagens de programação como SQL e PHP, respectivamente. A plataforma visa estruturar um centro de documentação de referência que reflita informações atualizadas e contextualizadas sobre as dimensões regionais da Educação Profissional e Tecnológica (EPT) para servir de apoio para estudos posteriores.

Research paper thumbnail of Impacto econômico da execução do projeto estrutural em uma residência localizada no bairro Tarumã em Manaus/Amazonas

Brazilian Journal of Development

O projeto estrutural na execução de obras influencia diretamente a eficácia construtiva final, ta... more O projeto estrutural na execução de obras influencia diretamente a eficácia construtiva final, tanto em obras de baixa quanto de alta complexidade. Através de dimensionamentos estruturais é possível obter dados específicos relevantes ao levantamento de materiais, decisões de métodos construtivos, técnicas de planejamento e otimização de cronograma, além de corroborar no efetivo orçamento de uma obra, controle de riscos e patologias. Nesse contexto, o trabalho tem como objetivo estudar o impacto econômico estrutural em uma obra residencial no localizada no bairro Tarumã, em Manaus/Amazonas. Foi verificado através das planilhas de custos e análises de dados, que os serviços da estrutura possuem significante diferença entre o custo estimado e executado. Contudo, as etapas finalizadas demonstraram que a construção da residência ocorreu de maneira satisfatória.

Research paper thumbnail of Estudo do processo construtivo de um protótipo que servirá como base para uma residência unifamiliar utilizando painel monolítico em Manaus/Amazonas

Brazilian Journal of Development

As tecnologias construtivas da engenharia avançam em diversos segmentos simultaneamente, o que co... more As tecnologias construtivas da engenharia avançam em diversos segmentos simultaneamente, o que contribui para a aplicação de sistemas construtivos diferentes dos convencionais, entretanto com boa eficiência competitiva ao mercado. Dessa forma, o sistema construtivo monolítico com placas de poliestireno expandido (EPS) é um sistema estruturado por duas malhas de aço eletrossoldadas entre si, em sua maioria com fundação de lajes de concreto, sem pilares ou vigas em até dois pavimentos, o que garante rapidez na execução e economia de custo. Esse artigo, portanto, demonstra o processo construtivo de um protótipo que servirá como base para uma residência unifamiliar usando painel monolítico de EPS, em Manaus/Amazonas. A confecção do protótipo de poliestireno expandido teve duração de dois dias enxutos dividido em etapas de execução e após a conclusão dos serviços o protótipo mostrou-se aplicável e eficaz ao que se propõe um sistema monolítico.

Research paper thumbnail of Análise do processo elétrico industrializado de um edifício em Manaus / Analysis of the industrialized electrical process of a building in Manaus

Brazilian Journal of Development

A industrialização no setor da Construção Civil está evoluindo nas últimas décadas, devido a comp... more A industrialização no setor da Construção Civil está evoluindo nas últimas décadas, devido a competitividade do mercado entre as empresas, dessa forma, os aprimoramentos dos métodos construtivos estão sendo cada vez mais estudados, fazendo com que a busca por otimização, produtividade e diminuição de desperdícios de materiais alavanquem na atualidade. Através da literatura, pesquisa bibliográfica e estudo de caso, foi feito o acompanhamento da produtividade desse sistema em um empreendimento de grande porte. Sendo assim, o objetivo deste artigo é conhecer o desenvolvimento e o processo de fabricação, entendendo o método construtivo da Rede Elétrica Otimizada, a qual veio para garantir a diminuição de tempo na entrega de obras multifamiliares. Para oferecer embasamento teórico no estudo em questão, foi realizado o levantamento de todo o material didático necessário através da pesquisa bibliográfica, apresentando conceitos de diferentes autores, possibilitando assim o comparativo e um...

Research paper thumbnail of Are the Liabilities of Newness and Smallness the Same for Male and Female Informal Entrepreneurs? Evidence from Brazil

Entrepreneurship Research Journal, 2020

Though challenges to female entrepreneurship are widely acknowledged in the settings of developed... more Though challenges to female entrepreneurship are widely acknowledged in the settings of developed countries or the context of formal firms, the challenges faced by female informal entrepreneurs in developing markets are less explored. Based on the liabilities of newness and smallness framework in organizational ecology, we draw on a sample of 2562 Brazilian informal firms, to examine the unique differences in the experience of newness and smallness between male and female informal entrepreneurs. With increasing firm age, female informal entrepreneurs realized lower firm revenues (inverted-U), however, the firm age and firm revenue association are linear for males. Informal firm performance did not vary by size between male and female informal entrepreneurs. The distinctive differences in firm revenues for male and female entrepreneurs have implications for informal entrepreneurship.

Research paper thumbnail of Closed versus open reduction of facial fractures in children and adolescents: A systematic review and meta-analysis

Journal of Clinical and Experimental Dentistry, 2021

Research paper thumbnail of Application-Level Load Balancing for Reactive Wireless Sensor Networks: An Approach Based on Constraint Optimization Problems

Intelligent Systems, 2020

As Wireless Sensor Networks-WSNs are being used more and more in applications with high demand fo... more As Wireless Sensor Networks-WSNs are being used more and more in applications with high demand for the processing of videos and images, the processing load of the nodes also must be considered by energy-saving strategies. Usually, these strategies focused only on communication. The overloading of nodes can result in a degraded performance regarding the network lifetime and availability of the provided services. A few algorithms, based on heuristics, have been proposed in the literature to balance the load at the application level. These algorithms drawnback are the lack of quality assurance. Thus, this work presents a novel semi-distributed solution, applying techniques to solve Constraint Optimization Problem-COP on the load balancing in a WSN. Our approach guarantee that all events are processed during the lifetime of the network and that there is a fixed number of exchanged messages per event, only reducing the lifetime of the network by an estimable time. Experimental results pointed out that the proposed approach allows the network, while alive, to sense all happened events each day, and its performance is better than the one achieved by the state-of-the-art for lower density networks.

Research paper thumbnail of The relation between public assistance and self-employment in census tracts: a long-term perspective

Journal of Evolutionary Economics, 2021

We present evidence on the long-term relationship between the breadth (the proportion of househol... more We present evidence on the long-term relationship between the breadth (the proportion of households) and depth (the amount per household) of public assistance and the prevalence of self-employment in US neighbourhoods. The analysis of decennial data of 71,437 census tracts over four decades (1970 to 2000) shows that the poverty ratio lowers self-employment, and that breadth (but not depth) of public assistance mitigates the negative relationship between the poverty ratio and self-employment. The results are robust to alternate model specifications and are informative about the distributional effects of welfare spendings.

Research paper thumbnail of Impact of the COVID-19 pandemic on the hours lost by self-employed racial minorities: evidence from Brazil

Small Business Economics, 2021

month. The disproportionate loss of work hours by the self-employed from racial minority groups d... more month. The disproportionate loss of work hours by the self-employed from racial minority groups during the COVID-19 pandemic in a developing country context calls for a closer examination and assessment of the long-term impact of COVID-19 on racial minorities. Plain English Summary Large-scale evidence from Brazil: racial minorities lost more hours per month than other groups during the COVID-19 pandemic. Racial minorities face systemic discrimination in setting up and developing their businesses, especially in developing countries. We test whether during the COVID-19 pandemic self-employed racial minorities in Brazil lost more hours of work relative to employed racial minorities. We create a matched sample of employed and self-employed individuals based on age, sex, education categories, COVID-19 self-reported symptom index, income deciles, house ownership categories, week of the interview, state of the interview, and industry. We find that across racial minority groups, the hours lost by the self-employed were substantive during the pandemic, signaling that Brazilian policymakers should pay greater attention to the relief funds allocated to and policies geared towards self-employed racial minorities.

Research paper thumbnail of Determining Methamphetamine in Urine by Molecularly Imprinted Polymer Assisted Paper Spray Ionization Mass Spectrometry

Journal of the Brazilian Chemical Society, 2021

The usefulness of molecularly imprinted polymer assisted paper spray ionization mass spectrometry... more The usefulness of molecularly imprinted polymer assisted paper spray ionization mass spectrometry (MIP-PSI-MS) for the determination of methamphetamine in urine has been demonstrated. MIP-PSI-MS is a method in which a MIP is synthesized on the surface of a paper, producing a chemically selective paper surface with molecular recognition sites for a target analyte. The analyte is extracted by the MIP substrate, which is posteriorly used for conventional PSI-MS analysis. As methamphetamine is one of the most widely used drugs of abuse in the world, it was selected to be studied in synthetic urine by the MIP-PSI-MS method. Methamphetamine was detected at higher ion signals compared to other different drugs, such as lysergic acid diethylamide (LSD) and cocaine, suggesting that MIP-PSI-MS has a chemical affinity for methamphetamine. In experiments to validate the method, a linear calibration curve was achieved with R-squared (R 2) > 0.99. Limit of detection (LOD) and limit of quantification (LOQ) were determined to be 0.8 and 2.8 µg L-1 , respectively. Precision (relative standard deviation) and accuracy (relative error) were less than 10%, and the recoveries were close to 100%. The matrix effect was below 10%. These data demonstrate the possibility of using MIP-PSI-MS as an analytical tool for a specific/ selective analysis of methamphetamine in forensic sciences.

Research paper thumbnail of Paper Spray Ionization Mass Spectrometry as a Potential Tool for Early Diagnosis of Cervical Cancer

Research paper thumbnail of Decentralized Governance of Digital Platforms

Journal of Management, 2020

Over the past decade, the rise of blockchain technology has led to the emergence of a growing num... more Over the past decade, the rise of blockchain technology has led to the emergence of a growing number of decentralized platforms that are governed less by platform owners and more through community efforts. The emergence of blockchain platforms offers a unique opportunity to examine alternative structures for platform governance and to develop a theory around the value of centralized, semi-decentralized, and decentralized governance. Drawing on mechanism design theory, we evaluate the tradeoffs between centralization and decentralization and hypothesize semi-decentralization as a higher performing governance structure. Empirical evidence from the blockchain industry shows that decentralization has an inverted U-shaped relationship with platforms’ market capitalization, developer attention, and development activity. We further examine factors driving the decentralization of platform governance and find that digital platforms of the infrastructure layer—relative to those of the applica...

Research paper thumbnail of Efeito Da Adubação Nitrogenada Em Cobertura Na Severidade Da Ferrugem Comum Do Milho

JOURNAL OF NEOTROPICAL AGRICULTURE, 2017

A adubação nitrogenada pode interferir positivamente ou negativamente na intensidade de diversas ... more A adubação nitrogenada pode interferir positivamente ou negativamente na intensidade de diversas doenças das plantas. Neste contexto, este estudo objetivou avaliar o efeito da aplicação de doses de nitrogênio em cobertura na severidade da ferrugem comum do milho (Puccinia sorghi). O experimento foi instalado na Fazenda Experimental da EPAMIG, em Prudente de Morais (MG), utilizando-se o híbrido de milho-verde AG 4051. O delineamento experimental adotado foi de blocos ao acaso com cinco tratamentos e três repetições. Os tratamentos constituíram da aplicação de cinco doses de N (0, 60, 120, 180 e 240 kg ha-1) na forma de ureia em cobertura. Foram realizadas cinco avaliações (em intervalo semanal) da severidade da doença em 3 folhas marcadas (2 acima e 1 abaixo da espiga) em seis plantas por parcela e ao final, calculou-se a área abaixo da curva de progresso da doença (AACPD). A equação polinomial quadrática (y = 707,9 + 3,34x – 0,0107x2) foi a que melhor se ajustou (R2 = 0,86). A sever...

Research paper thumbnail of Substratos Orgânicos Na Produção De Mudas De Cafeeiro Em Tubetes

REVISTA DE AGRICULTURA NEOTROPICAL, 2017

Considerando-se a importância das mudas na formação de lavoura cafeeira (Coffea arabica L.), obje... more Considerando-se a importância das mudas na formação de lavoura cafeeira (Coffea arabica L.), objetivou-se avaliar características agronômicas e índices de qualidade de mudas do cafeeiro cv. Topázio MG 1190, produzidos em tubetes com a utilização de diferentes proporções de materiais orgânicos no substrato comercial. O experimento foi em delineamento experimental em blocos casualizados, dispostos em esquema fatorial 4 x 4, sendo quatro fontes de esterco: bovino, cama de frango, coelho e suíno em quatro proporções (0, 20, 40 e 60%) no substrato comercial Bioplant® com quatro repetições. As parcelas foram formadas por sete plantas dispostas em tubetes com volume de 180 mL. Foram avaliadas as características agronômicas: altura da planta, número de par de folhas, área foliar, diâmetro de caule, massa seca da parte aérea, massa seca da raiz, relação altura da planta e diâmetro de caule, relação massa seca de parte aérea e massa seca da raiz e índice de qualidade de Dickson (IQD). Os res...

Research paper thumbnail of Determinação De Designer Drugs Em Saliva Por Paper Spray Mass Spectrometry

Química Nova, 2019

Recebido em 23/01/2019; aceito em 06/05/2019; publicado na web em 27/06/2019 DETERMINATION OF DES... more Recebido em 23/01/2019; aceito em 06/05/2019; publicado na web em 27/06/2019 DETERMINATION OF DESIGNER DRUGS IN SALIVA BY PAPER SPRAY MASS SPECTROMETRY. Determination of two drugs of abuse in saliva has been performed by Paper Spray Ionization Mass Spectrometry (PSI-MS) using a Molecularly Imprinted Polymer (MIP) coated paper as substrate. The method has been optimized for quantification of 3,4-methylenedioxy-N-methylamphetamine (MDMA) and methamphetamine, 3,4-methylenedioxyamphetamine (MDA) from synthetic saliva samples. Rapid analysis (~ 1 min) of designer drugs in saliva is demonstrated using MIP-PSI-MS. Both precursor ions of MDMA and MDA were confirmed by tandem mass spectrometry (MS/MS) experiments by elucidating the fragmentation patterns formed via collisioninduced dissociation (CID). The MIP-PSI-MS method showed greater selectivity for MDMA and MDA in comparison with other analytes. Signal intensity ratios of the most important transitions for MDMA (194 → 163) and MDA (180 → 163) were found linear (R > 0,99) in the range 25-500 µg L-1. The LOD and LOQ for MDMA were 1.11 µg L-1 and 18.73 µg L-1 , respectively, and for MDA were 3.42 µg L-1 and 21.66 µg L-1 , respectively. The precision and accuracy values were determined below 4%, and the recoveries about 100%, without pre-concentration/enrichment or separation steps. The MIP-PSI-MS method displays the potential for rapid screening for selective quantitative determination of illicit drugs in saliva samples.

Research paper thumbnail of INTERAÇÃO Allium cepa X Stemphylium spp ASSOCIADOS AO USO DO INDUTOR DE RESISTÊNCIA ACIBENZOLAR S-METIL

Agrarian Academy, 2018

RESUMO Diversos agentes vêm sendo estudados como indutores de respostas de defesa em plantas. Ent... more RESUMO Diversos agentes vêm sendo estudados como indutores de respostas de defesa em plantas. Entre esses destaca-se o Acibenzolar S-metil (ASM) que age induzindo a expressão de proteínas PR e enzimas relacionadas com a síntese de lignina como as peroxidases bem como fitoalexinas que são compostos tóxicos aos patógenos, possibilitando aumento da resistência das plantas. Desse modo, objetivou-se estudar o efeito do ASM na manifestação de respostas de defesa a Stemphylium spp. em mudas de cebola, por meio da determinação da atividade da peroxidase. O delineamento experimental utilizado foi o inteiramente casualizado no esquema de parcelas subdivididas no tempo. Foram realizados cinco tratamentos, quatro avaliações no intervalo de 1, 24, 48 e 72 horas após a inoculação do patógeno e quatro repetições. Os tratamentos foram T1-Testemunha absoluta, T2-com ASM e sem patógeno, T3-sem ASM e com patógeno, T4-com o patógeno e ASM 0,2 mg/mL e T5-com patógeno e ASM 0,4 mg/mL. Os valores da atividade da enzima peroxidase foram menores, durante os períodos de avaliação, nos tratamentos com ASM ou Stemphylium spp. em comparação com a testemunha. Nos tratamentos com a inoculação do patógeno, independente da presença do ASM a atividade de peroxidase diminuiu ao longo do período de avaliação. Os resultados sugerem que a presença do patógeno é mais efetiva em induzir alterações na atividade enzimática de peroxidase que o ASM, porém somente o comportamento da peroxidase não foi suficiente para entender o seu papel na defesa do vegetal. PALAVRAS-CHAVE: Bion ® , cebola, peroxidase.

Research paper thumbnail of Surgical treatment of Adenomatoid Odontogenic Tumor: A 5-year follow-up

Revista Portuguesa de Estomatologia, Medicina Dentária e Cirurgia Maxilofacial, 2017

Adenomatoid odontogenic tumor (AOT) is a rare odontogenic tumor with limited growth and usually a... more Adenomatoid odontogenic tumor (AOT) is a rare odontogenic tumor with limited growth and usually associated with an unerupted permanent tooth. It is a benign lesion, with a low rate of recurrence after surgical treatment. This is a case report of an 11-year-old female with an asymptomatic tumor growth on the maxilla and palatal displacement of the lateral incisor. A unilocular lesion surrounding the coronal impacted right upper canine and the displacement of premolars were observed radiographically. After incisional biopsy, the tumor was diagnosed as AOT. The enucleation of the lesion and the removal of the impacted canine was performed. Four months later, the patient had not shown any signs of recurrence and was referred for orthodontic treatment. New surgical procedure was performed to remove the gums that covered the premolars to promote their eruption. Five years later, the premolars are in position in the dental arch and there are no signs of recurrence of the lesion.

Research paper thumbnail of Taking advantage of an unerupted third molar: a case report

Dental Press Journal of Orthodontics, 2017

Introduction: Treatments with dental surgery seek to displace tooth to the correct position withi... more Introduction: Treatments with dental surgery seek to displace tooth to the correct position within the dental arch. Objective: To report a clinical case that took advantage of an unerupted third molar. Case history: A male patient, 18 years of age, was referred by his dentist to evaluate the third molars. The clinical exam revealed no visible lower third molars. The computed tomography (CT) exam showed the presence of a supernumerary tooth in the region of the mandibular ramus, on the left side, and impaction of the third molar, which was causing root resorption on the second molar, thus making it impossible to remain in the buccal cavity. The preferred option, therefore, was to remove both second molar and the supernumerary tooth, in addition to attaching a device to the third molar during surgery for further traction. Results: After 12 months, the third molar reached the proper position. Conclusion: When a mandibular second permanent molar shows an atypical root resorption, an imp...

Research paper thumbnail of Laser Ablation Electrospray Ionization Mass Spectrometry with Ion Mobility Separation Reveals Metabolites in the Symbiotic Interactions of Soybean Roots and Rhizobia

The Plant journal : for cell and molecular biology, Jan 10, 2017

Technologies enabling in situ metabolic profiling of living plant systems are invaluable for unde... more Technologies enabling in situ metabolic profiling of living plant systems are invaluable for understanding physiological processes and could be used for rapid phenotypic screening (e.g., to produce plants with superior biological nitrogen fixing ability). The symbiotic interaction between legumes and nitrogen-fixing soil bacteria results in a specialized plant organ (i.e., root nodule) where the exchange of nutrients between host and endosymbiont occurs. Laser ablation electrospray ionization mass spectrometry (LAESI-MS) is a method that can be performed under ambient conditions requiring minimal sample preparation. Here, we employed LAESI-MS to explore the well-characterized symbiosis between soybean (Glycine max L. Merr.) and its compatible symbiont, Bradyrhizobium japonicum. The utilization of ion mobility separation (IMS) improved the molecular coverage, selectivity, and identification of the detected biomolecules. Specifically, incorporation of IMS resulted in an increase of 15...

Research paper thumbnail of Differentiation of Toxic and Non-Toxic Leaves of Jatropha curcas L. Genotypes by Leaf Spray Mass Spectrometry

Journal of the Brazilian Chemical Society, 2016

Jatropha curcas L. is an oil crop that has been studied as a potential source of biodiesel. A hig... more Jatropha curcas L. is an oil crop that has been studied as a potential source of biodiesel. A high protein pie is produced as a byproduct of the biodiesel production, which could be used as animal feed. However, the pie has toxic compounds, as phorbol esters and other toxins, which prevents the use as animal feed. For this reason, Embrapa (Brazilian Agricultural Research Corporation) has been working in genetic breeding to develop non-toxic J. curcas genotypes. To evaluate this process, a simple and fast analytical technique was employed to obtain responses in a short time. Leaf spray (LS) is a recent ambient ionization mass spectrometry technique in which the sample itself serves as support and ion source. Here, toxic and non-toxic J. curcas leaves were differentiated by LS using a linear ion trap mass spectrometer and partial least squares discriminant analysis (PLS-DA) model chemometrics. It was possible to differentiate toxic and non-toxic leaves and to identify the m/z values that contribute to discrimination between the groups.

Research paper thumbnail of Repositório Digital: instrumento de aprendizagem na Educação Profissional

Anais do XXII Workshop de Informática na Escola (WIE 2016), 2016

Este trabalho tem o objetivo de apresentar o desenvolvimento e implementação de um repositório di... more Este trabalho tem o objetivo de apresentar o desenvolvimento e implementação de um repositório digital e a simultânea criação de um website. Concebido por alunos do curso Técnico em Informática para Internet integrado ao ensino médio, esse instrumento de aprendizagem para a Educação Profissional foi dividido em duas etapas: o desenvolvimento do banco de dados e a implementação do website, ambos utilizando linguagens de programação como SQL e PHP, respectivamente. A plataforma visa estruturar um centro de documentação de referência que reflita informações atualizadas e contextualizadas sobre as dimensões regionais da Educação Profissional e Tecnológica (EPT) para servir de apoio para estudos posteriores.