277 research outputs found
Estrutura interna de testes de cohecimento em Física : um exemplo em mecânica
Research findings are presented concerning the internal structure analysis of a multiple choice test constructed to detect whether or not the student has the Newtonian conception of the interrelationship between force and motion. These findings show that the test has two different but related factors: one subset of items checks students' ability to identify forces in certain physical situations according to the Newtonian view while another subset checks whether or not they relate the resultant force with acceleration. In addition, the analysis also shows that the two subsets have slightly different predicting power concerning student performance in mechanics. This kind of analysis might be very relevant for teacher's work regarding learning evaluation
Failure regime in (1+1) dimensions in fibrous materials
In this paper, we introduce a model for fracture in fibrous materials that
takes into account the rupture height of the fibers, in contrast with previous
models. Thus, we obtain the profile of the fracture and calculate its
roughness, defined as the variance around the mean height. We investigate the
relationship between the fracture roughness and the fracture toughness.Comment: 4 pages, 4 figures.eps, Revte
Manejo do solo utilizando plantas de cobertura, híbridos e nitrogênio na produtividade do milho.
O experimento foi conduzido com milho safrinha na Embrapa Arroz e Feijão, em Latossolo Vermelho Distrófico para verificar o efeito do manejo do solo com a utilização de plantas de cobertura, híbridos e doses de nitrogênio em cobertura na produtividade do milho. O delineamento experimental foi o de blocos ao acaso com três repetições em arranjo de parcelas sub-sub-divididas
Nitrogen fluxes from irrigated common-bean as affected by mulching and mineral fertilization.
The objective of this work was to measure the fluxes of N2O‑N and NH3‑N throughout the growing season of irrigated common‑bean (Phaseolus vulgaris), as affected by mulching and mineral fertilization. Fluxes of N2O‑N and NH3‑N were evaluated in areas with or without Congo signal grass mulching (Urochloa ruziziensis) or mineral fertilization. Fluxes of N were also measured in a native Cerrado area, which served as reference. Total N2O‑N and NH3‑N emissions were positively related to the increasing concentrations of moisture, ammonium, and nitrate in the crop system, within 0.5 m soil depth. Carbon content in the substrate and microbial biomass within 0.1 m soil depth were favoured by Congo signal grass and related to higher emissions of N2O‑N, regardless of N fertilization. Emission factors (N losses from the applied mineral nitrogen) for N2O‑N (0.01?0.02%) and NH3‑N (0.3?0.6%) were lower than the default value recognized by the Intergovernmental Panel on Climate Change. Mulch of Congo signal grass benefits N2O‑N emission regardless of N fertilization
"A Nova Eletricidade: Aplica\c{c}\~oes, Riscos e Tend\^encias da IA Moderna -- "The New Electricity": Applications, Risks, and Trends in Current AI
The thought-provoking analogy between AI and electricity, made by computer
scientist and entrepreneur Andrew Ng, summarizes the deep transformation that
recent advances in Artificial Intelligence (AI) have triggered in the world.
This chapter presents an overview of the ever-evolving landscape of AI, written
in Portuguese. With no intent to exhaust the subject, we explore the AI
applications that are redefining sectors of the economy, impacting society and
humanity. We analyze the risks that may come along with rapid technological
progress and future trends in AI, an area that is on the path to becoming a
general-purpose technology, just like electricity, which revolutionized society
in the 19th and 20th centuries.
A provocativa compara\c{c}\~ao entre IA e eletricidade, feita pelo cientista
da computa\c{c}\~ao e empreendedor Andrew Ng, resume a profunda
transforma\c{c}\~ao que os recentes avan\c{c}os em Intelig\^encia Artificial
(IA) t\^em desencadeado no mundo. Este cap\'itulo apresenta uma vis\~ao geral
pela paisagem em constante evolu\c{c}\~ao da IA. Sem pretens\~oes de exaurir o
assunto, exploramos as aplica\c{c}\~oes que est\~ao redefinindo setores da
economia, impactando a sociedade e a humanidade. Analisamos os riscos que
acompanham o r\'apido progresso tecnol\'ogico e as tend\^encias futuras da IA,
\'area que trilha o caminho para se tornar uma tecnologia de prop\'osito geral,
assim como a eletricidade, que revolucionou a sociedade dos s\'eculos XIX e XX.Comment: In Portugues
Proposição de um sistema de produção de mudas de mandioquinha-salsa.
O objetivo desta publicação é trazer subsídios para a produção de mudas de alta qualidade genética, fitossanitária e fisiológica, com responsabilidade técnica, passíveis de certificação, em atendimento a demandas da cadeia produtiva e da sociedade como um todo. Assim, visa à melhoria do processo e da qualidade do produto, com consequente redução dos problemas fitossanitários e aumento na produtividade
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