1,928 research outputs found

    APLICAÇÃO DE REDES NEURAIS ARTIFICIAIS NA PREDIÇÃO DE PREÇOS DE AÇÕES POR INDICADORES FINANCEIROS

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    Resumo: O trabalho tem como objetivo desenvolver um modelo previsão de preços de ações negociadas na BM&Fbovespa, utilizando forma conjunta os indicadores tradicionais de rentabilidade, de liquidez e de endividamento utilizados em estudos empíricos sobre a temática, por meio de 8 indicadores. O modelo foi desenvolvido através das Redes Neurais Artificias, uma metodologia ainda pouco aplicada na área de finanças. Os dados foram extraídos da base de dados Economatica, com séries trimestrais, o período de análise compreende os anos de 2012 a 2017 e a amostra é composta 371 companhias. Como resultado, o modelo de rede neural artificial proposto apresentou desempenho relativamente satisfatório, entretanto os indicadores de desempenho não são capazes de, sozinhos, fornecer informações suficientes para a rede

    Analysis of secondary refining slag parameters with focus on inclusion cleanliness

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    Secondary refining slag samples with different chemical compositions (45-54 % CaO, 7-13 % Al2O3, 20-29 % SiO2, 9-16 % MgO, 0-5 % CaF2) were investigated to verify the influence of their effective viscosity on inclusion cleanliness of DIN 38MnS6 in a steelmaking plant. The steel samples were collected during the production process for analysis of inclusions. Using the commercial software FactSage 6.4, thermodynamic calculations were performed to determine the effective viscosity, solid fraction, liquid fraction and MgO saturation point of these slags at 1560ºC. The results showed that all the slags were saturated in MgO, revealing a better protection of the ladle refractory. The addition of 2 to 5 % of CaF2 reduced the effective viscosity values for the analyzed slags from 0.45 Pa∙s to 0.10 Pa∙s , in comparison to the slags without the addition of CaF2, with an effective viscosity of 0.40 Pa∙s, 0.27 Pa∙s and 0.22 Pa∙s, decreasing the level of non-metallic inclusions for some of the analysed heats. However, it was detected during the manufacturing process that high slag fluidity and re-oxidation events continue to be a challenge associated with reducing the level of non-metallic inclusions

    Analysis of spinel based inclusions during the last stage of the steelmaking process of SAE 52100

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    Al2 O3 (alumina) and MgO·Al2 O3 (spinel) inclusions cause valve obstruction (clogging) in continuous casting and can deteriorate the quality of the final product. In this context, industrial heats of the bearing steel SAE 52100 was examined. Samples were collected in the final steps of the steelmaking process, both after vacuum treatment and during continuous casting. A scanning electron microscope (SEM) equipped with a energy-dispersive spectrometer (EDS) and automated particle characterization analysis was used to characterize the inclusions present in the steel samples. Thermodynamic calculations were performed with the commercial software FactSageTM 7.2. Based on thermodynamic predictions, parameters such as solid fraction, liquid fraction, MgO saturation point of the slags, content of dissolved elements in steel (Al, Mg, Ca,...) and the construction of a phase stability diagram were determined. The results in this study showed a tendency for increase in MgO content in the inclusions with the decrease of %FeO and SiO2 contents in the slag, an increase of binary basicity (%CaO/%SiO2 ). It is verified that the MgO contents in the slag were close to the saturation, increasing the probability for the formation of inclusions rich in MgO and/or spinel. On the other hand, stability diagrams confirm the formation of spinel inclusions for each of the heats analyzed. During the final step of the steelmaking process, there is a tendency for re-oxidation, which is verified by an increase in the density of inclusions (or total oxygen TO values)

    The insecurity of Vale’s dams in Minas Gerais, Brazil: applying activity theory to disaster analysis

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    The objective of this article is to point out hypotheses of contradictions historically incubated in Vale’s activity systems and that may have led to Brazil’s biggest environmental disaster, the B I dam break in Brumadinho, and the interdiction of many other dams owned by Vale in the state of Minas Gerais, Brazil. This is a case analysis from secondary data available in interviews, documents, and texts published in different media between 2011 and 2021. We try to demonstrate, from the Historical-Cultural Theory of Activity, the contradictions verified in and between Vale’s activity systems, since the company distributed large dividends to its shareholders, remunerated its directors as never before, reduced costs in relation to incomes, and brutally reduced internal debt, but keeping insufficient investments in dam management, culminating with the break of B I in 2019 and with 29 dams interdicted in March 2021. Financialization has become central to the company’s operations. This study points to a methodological path of the interdisciplinary dialogue to help clarify how strategic managerial decisions, especially those of financial management, could influence the production, maintenance, and safety management of tailings dams.O objetivo deste artigo é apontar hipóteses de contradições que estariam incubadas historicamente nos sistemas de atividades da Vale, e que podem ter levado ao maior desastre ambiental do Brasil: o rompimento da barragem B I em Brumadinho, bem como à interdição de muitas outras barragens da empresa no estado de Minas Gerais, Brasil. Trata-se de uma análise de caso a partir de dados secundários disponíveis em entrevistas, documentos e textos publicados em diferentes mídias entre 2011 e 2021. Procuramos demonstrar, a partir da Teoria Histórico-Cultural da Atividade, as contradições verificadas em e entre sistemas de atividades da Vale, pois a empresa distribuiu dividendos vultosos aos seus acionistas, remunerou como nunca seus diretores, reduziu os custos em relação às receitas e diminuiu brutalmente a dívida interna, mas manteve investimentos insuficientes na gestão das barragens, culminando no rompimento da B I em 2019 e em 29 barragens interditadas em março de 2021. A financeirização tornou-se central para as operações da empresa. Este estudo aponta para um caminho metodológico do diálogo interdisciplinar que ajuda a esclarecer como as decisões gerenciais estratégicas, especialmente aquelas da gestão financeira, poderiam influenciar a gestão de produção, de manutenção e de segurança das barragens de rejeitos

    Microdissection testicular sperm extraction causes spermatogenic alterations in the contralateral testis

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    Testicular sperm extraction (TESE) associated with intracytoplasmic sperm injection has allowed many men presenting non-obstructive azoospermia to achieve fatherhood. Microdissection TESE (microTESE) was proposed as a method to improve sperm retrieval rates in these patients; however, there have been failures. Little is known about whether microTESE leads to spermatogenic alterations in the contralateral testis. We assessed histological outcomes of experimental microTESE in the contralateral testis of adult male rabbits. Nine adult male rabbits were divided into three groups: control (testicular biopsy to observe normal histological and morphometric values), sham (incision of the tunica vaginalis, and a contralateral testicular biopsy to observe histological and morphometric patterns, 45 days later), and study (left testicular microTESE, and a right testicular biopsy to observe histological and morphometric patterns, 45 days later). Sections were assessed by calculating Johnsen-like scores, and measuring total tubule diameter, lumen diameter and epithelial height. the results were compared using ANOVA and Bonferroni's statistical analysis. Morphometric evaluation of the seminiferous tubules did not demonstrate differences between the three groups. However, microTESE caused spermatogenic alterations, leading to maturation arrest in the contralateral testis.Universidade Federal de São Paulo, Dept Cirurgia, Div Urol, Secao Reprod Humana, São Paulo, BrazilUniv Estadual Paulista, Dept Biol, Inst Biociencias Letras & Ciencias Exatas Sao Jos, Sao Jose Do Rio Preto, SP, BrazilUniversidade Federal de São Paulo, Dept Cirurgia, Div Urol, Secao Reprod Humana, São Paulo, BrazilWeb of Scienc

    Fatores que influenciam o impacto da saúde bucal nas atividades diárias de adolescentes, adultos e idosos

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    OBJETIVO: Analisar se variáveis clínicas, sociodemográficas e de acesso aos serviços odontológicos influenciam o impacto da saúde bucal nas atividades diárias de adolescentes, adultos e idosos. MÉTODOS: Estudo transversal com dados secundários da Pesquisa Estadual de Saúde Bucal (SB São Paulo 2015) realizada em 163 municípios de São Paulo. Participaram do inquérito 17.560 indivíduos de três grupos etários: adolescentes de 15–19 anos (n = 5.558), adultos de 35–44 anos (n = 6.051) e idosos de 65 anos ou mais (n = 5.951). A seleção foi feita por amostra probabilística por conglomerados em dois estágios. A variável desfecho foi o impacto da saúde bucal sobre as atividades diárias, avaliado pelo questionário Oral Impacts on Daily Performances, contendo questões sobre comer, falar, higiene bucal, relaxamento, prática esportiva, sorriso, estudo ou trabalho, contato social e sono. O Oral Impacts on Daily Performances foi dicotomizado em com e sem impacto. As variáveis independentes foram as sociodemográficas, clínicas e de acesso, divididas em três blocos. Realizou-se análise de regressão logística múltipla hierarquizada considerando o plano amostral complexo de conglomerados. Cada observação recebeu um peso específico, dependendo da localização que resultou em frequências ponderadas e ajustadas para o efeito do delineamento. RESULTADOS: A presença de impacto da saúde bucal foi constatada em 27,9% dos indivíduos. No bloco 1, o sexo feminino e o grupo étnico preto/pardo tiveram maior chance de impacto da saúde bucal na qualidade de vida, bem como os adultos e idosos em relação aos adolescentes. No bloco 2, a renda familiar até R1.500teveassociac\ca~ocomapresenc\cadeimpacto.Nobloco3,osindivıˊduosquerelataramdordedente,frequentaramoservic\copuˊblicoeprocuraramtratamentoodontoloˊgicotiverammaiorchancedeimpacto.CONCLUSO~ES:Asvariaˊveissociodemograˊficas,clıˊnicaedeacessoaoservic\codesauˊdeinfluenciamoimpactodasauˊdebucalnasatividadesdiaˊriasdeadolescentes,adultoseidosos.OBJECTIVE:Analyzeifclinical,sociodemographicandaccesstodentalservicesvariablesinfluencetheimpactoforalhealthonthedailyactivitiesofadolescents,adultsandolderadults.METHODS:Across−sectionalstudywithsecondarydatafromtheStateOralHealthSurvey(SBSa~oPaulo2015)conductedin163citiesofSa~oPaulo.Atotalof17,560individualsfromthreeagegroups:15–19−year−old(n=5,558),35–44−year−old(n=6,051),andolderpeopleof65yearsormore(n=5,951)participatedinthesurvey.Theselectionwasmadebyprobabilisticsamplebyconglomeratesintwostages.Theendpointvariablewastheimpactoforalhealthondailyactivities,evaluatedbytheOralImpactsonDailyPerformancesquestionnaire,containingquestionsabouteating,talking,oralhygiene,relaxation,sportspractice,smile,studyorwork,socialcontact,andsleep.OralImpactsonDailyPerformanceswasdichotomizedwithandwithoutimpact.Theindependentvariablesweresociodemographic,clinicalandaccessvariables,dividedintothreeblocks.Ahierarchicalmultiplelogisticregressionanalysiswasperformedconsideringthecomplexsamplingplanofclusters.Eachobservationreceivedaspecificweight,dependingonthelocationthatresultedinweightedfrequenciesandadjustedforthedesigneffect.RESULTS:Thepresenceoforalhealthimpactwasobservedin27.91.500 teve associação com a presença de impacto. No bloco 3, os indivíduos que relataram dor de dente, frequentaram o serviço público e procuraram tratamento odontológico tiveram maior chance de impacto. CONCLUSÕES: As variáveis sociodemográficas, clínica e de acesso ao serviço de saúde influenciam o impacto da saúde bucal nas atividades diárias de adolescentes, adultos e idosos.OBJECTIVE: Analyze if clinical, sociodemographic and access to dental services variables influence the impact of oral health on the daily activities of adolescents, adults and older adults. METHODS: A cross-sectional study with secondary data from the State Oral Health Survey (SB São Paulo 2015) conducted in 163 cities of São Paulo. A total of 17,560 individuals from three age groups: 15–19-year-old (n = 5,558), 35–44-year-old (n = 6,051), and older people of 65 years or more (n = 5,951) participated in the survey. The selection was made by probabilistic sample by conglomerates in two stages. The endpoint variable was the impact of oral health on daily activities, evaluated by the Oral Impacts on Daily Performances questionnaire, containing questions about eating, talking, oral hygiene, relaxation, sports practice, smile, study or work, social contact, and sleep. Oral Impacts on Daily Performances was dichotomized with and without impact. The independent variables were sociodemographic, clinical and access variables, divided into three blocks. A hierarchical multiple logistic regression analysis was performed considering the complex sampling plan of clusters. Each observation received a specific weight, depending on the location that resulted in weighted frequencies and adjusted for the design effect. RESULTS: The presence of oral health impact was observed in 27.9% of the individuals. In block 1, female gender and black/brown ethnic group had a greater chance of impact of oral health on quality of life, as well as the adults and the older adults in relation to adolescents. In block 2, family income up to R1,500 was associated with the presence of impact. In block 3, individuals who reported toothache, used the public service and sought dental treatment had a greater chance of impact. CONCLUSIONS: Sociodemographic, clinical and access to health services variables influence the impact of oral health on the daily activities of adolescents, adults and older adults

    Laboratório de mudança: método para compreensão da crise entre universidade pública e sociedade

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    The purpose of this article is to analyze if a method of developmental intervention helps the professionals of the activities in interinstitutional crises to form a historical understanding of the problems faced and to create solutions for them. We present a method called Change Laboratory (CL), inspired by the Theory of Historical-Cultural Activity (THCA). It is illustrated with an empirical case of intervention where the historical genesis and the contradictions that led to the crisis in the collaborative relationship between a public university and an educational health center were identified, between 2013 and 2015. Data obtained from records made during the intervention as well as interviews and comments from the participants were used for the study. As a result, the participants analyzed their activities historically and designed the future collaboration activity aimed at a solution to the crisis, within the scope of possible academicpedagogical relations linked to the Brazilian National Health System (SUS). The analysis suggests contradictions in the objects of health care and education activities that may be at the heart of the problematic relationship among institutions that need to develop activities collaboratively. The CL as a methodology of developmental intervention integrates diagnosis, learning, the participants’ protagonism and the creation of solutions as part of the same process.O objetivo deste artigo é analisar se um método de intervenção formativa contribui para que os profissionais de atividades colaborativas formem uma compreensão histórica dos problemas enfrentados em crises interinstitucionais e criem soluções para essas situações. Apresentamos o método Laboratório de Mudança (LM), inspirado na Teoria da Atividade Histórico-Cultural (TAHC). Ele é ilustrado com um caso empírico de intervenção na qual foi identificada a gênese histórica e as contradições que levaram à crise entre uma universidade pública e um centro de saúde escola. Para o estudo foram utilizados dados obtidos a partir de registros efetuados ao longo da intervenção, entre 2013 e 2015, assim como entrevistas e comentários dos participantes. Como resultado, eles analisaram historicamente suas atividades e desenharam novos cenários de colaboração futura, visando uma solução para a crise, no âmbito de possíveis relações acadêmico-pedagógicas vinculadas ao Sistema Único de Saúde (SUS). A análise sugere a existência de contradições nos objetos das atividades de assistência à saúde e educação que podem estar no cerne da relação problemática entre outras instituições semelhantes que precisam desenvolver atividades colaborativamente. O LM, enquanto metodologia de intervenção formativa, integra diagnóstico, aprendizagem, protagonismo dos participantes e criação de soluções como parte de um mesmo processo

    Individual And Contextual Factors Related To Dental Caries In Underprivileged Brazilian Adolescents

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    Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Background: Investigate the individual and contextual variables related to caries in underprivileged adolescents, and the disparity in distribution of the disease. Methods: Cross-sectional analytical study, conducted in the city of Piracicaba, SP, Brazil, in 2012. The probabilistic sample was composed of 1,179 adolescents from 15-19 years of age, randomly selected from 21 state schools and 34 Primary Health Units - Family Health (PHU-FH). The dependent variables studied were number of decayed teeth and caries experience (DMFT). The independent variables were classified into individual (clinical, sociodemographic, psychosocial, self-perception, impact on oral health, access to services, and quality of life) and contextual (social exclusion index, total number of residents in suburb, literacy rate, and the following variables given in percentages: residences in the home ownership category, provision of domestic sewerage, trash collection, families with income of over 1 minimum wage per month, and families without monthly income) variables. The multilevel regression model was estimated by the PROC GLIMMIX (Generalized Linear Models-Mixed) procedure, considering the individual variables as Level 1 and the contextual variables of the suburbs as Level 2. Adjustment of the model was evaluated by -2 Res Log Likelihood with alpha = 0.05. Results: As regards the individual variables, adolescents who declared having a prison inmate in the Family and resided in homes with a larger number of persons, showed a higher number of decayed teeth. There were a larger number of decayed teeth, a higher DMFT value, and worse self-perception as regards the health of their teeth and mouth. Other variables, such as being of the female gender, age and time since last visit to the dentist were related to the DMFT index. As regards the contextual variables, the DMFT was lower in suburbs with greater access to domestic sewage, and the number of decayed teeth was higher in suburbs with the worst social exclusion indices. Conclusion: Individual and contextual variables were associated with the presence of caries and DMFT index in underprivileged adolescents, indicating that they must be taken into consideration in the formulation of policies directed towards oral health promotion and prevention activities in this group.15Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [2011/03657-5, 2011/01768-4

    O Laboratório de Mudança como ferramenta para transformação colaborativa de atividades de trabalho: uma entrevista com Jaakko Virkkunen

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    On September 2012, the School of Public Health, University of São Paulo (FSP-USP), in cooperation with the University of Helsinki - Finland, held a Training Course for the Change Laboratory Method conducted by Professor Emeritus Jaakko Virkkunen, Ph.D. in Work Psychology and Professor at the Center for Research on Activity, Development and Learning (CRADLE), University of Helsinki. He has a broader experience in formative interventions and conceded this interview to Saúde e Sociedade Magazine. During the interview, the trajectory and history of this Center was presented, which has a long tradition in research based on the Cultural-Historical Activity Theory (CHAT) based on the work of L. S. Vygotsky and his followers. Jaakko Virkkunen took part along with other CRADLE researchers in the development of a method called Change Laboratory (CL), a consolidated tool already applied in many countries and different areas of activity. Theoretical aspects, principles, the importance of demand and experience of application of CL were presented during the interview. Furthermore, other differences among participatory research methods are mentioned. At the end, the interviewee presents suggestions about the use of the CL.Em setembro de 2012, a Faculdade de Saúde Pública da Universidade de São Paulo (FSP-USP), em cooperação com a Universidade de Helsinque (Finlândia), promoveu um curso de capacitação sobre o método do Laboratório de Mudança (LM) ministrado pelo Professor Emérito Jaakko Virkkunen, doutor em psicologia do trabalho e professor do Centro de Pesquisa em Atividade, Desenvolvimento e Aprendizagem (CRADLE), daquela instituição. Com uma ampla experiência em intervenções formativas, ele concedeu esta entrevista à Saúde e Sociedade. Durante a entrevista, foi apresentada a trajetória e história desse Centro, que possui uma longa tradição em pesquisas baseadas na teoria da atividade histórico-cultural (CHAT), por sua vez baseada no trabalho de L. S. Vygostky e seus seguidores. Virkkunen, juntamente com pesquisadores do CRADLE, desenvolveu o LM, uma ferramenta consolidada, já aplicada em vários países e em diferentes áreas de atividade. Aspectos teóricos, princípios, a importância da demanda e experiências de aplicação desse método foram apresentados durante a entrevista. Além disso, são mencionadas diferenças com outros métodos de intervenção e de pesquisas participativas. Ao final o entrevistado apresenta sugestões para o uso do LM
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