APRENDIZAGEM OBSERVACIONAL, FORMAÇÃO E EXPANSÃO DE CLASSES DE ESTÍMULOS EQUIVALENTES

This study investigated conditional discrimination acquisition, stimulus class formation and stimulus class expansion through a modeling procedure. Six college students were taught conditional discriminations with five stimulus sets. Stimuli were black line drawings of common objects against white backgrounds. BA relations were taught individually, in a manner similar to that typically described by the literature, without modeling, followed by the teaching of CA relations, taught through a modeling procedure. During the teaching of BA relations, correct and incorrect comparison selections were followed by differential reinforcement. During CA, subsequent DA relations and EA relations training, subjects were instructed to observe a model that actually made the selections and received differential reinforcement for that. After the teaching of BA and CA relations, symmetry, transitivity and equivalence tests were introduced, followed by DA and EA teaching and tests for equivalence class expansion. All participants showed equivalence class formation and all but one participant showed expanded classes to include stimulus sets D and E into the previously formed class. Whether the observed results were an exclusive function of modeling or a combination of modeling and sequential effects of the directing teaching of BA requires further investigation. Key words: modeling, stimulus equivalence, conditional discriminations, observational learningEste estudo teve como objetivo investigar se um procedimento de ensino por modelação pode produzir discriminações condicionais, formar classes de estímulos equivalentes, e expansão de classes, em seis estudantes universitários. Foram ensinadas discriminações condicionais entre cinco conjuntos de estímulos, através de tarefas de escolha de acordo com o modelo. Foram usados como estímulos desenhos de objetos comuns produzidos em linhas pretas sobre fundo branco. As relações BA foram ensinadas da maneira tipicamente descrita pela literatura, sem modelo, seguidas de ensino das relações CA, com modelo. No ensino das relações BA, os participantes escolhiam os estímulos de comparação e recebiam conseqüências diferenciais para escolhas corretas e incorretas. No ensino de CA, assim como no de DA e EA, os participantes foram instruídos a observar um demonstrador que selecionava os estímulos de comparação e recebia conseqüências diferenciais por suas escolhas. Após o ensino das relações BA CA, foram introduzidos os testes para verificar a emergência de simetria, transitividade e equivalência. Todos os participantes mostraram formação de classes equivalentes e cinco deles expansão de classes para os estímulos D e E. Discute-se se os resultados produzidos foram função exclusiva do ensino por modelação, ou uma combinação desses com efeitos seqüenciais do ensino individual e direto da primeira relação condicional. Palavras-chave: ensino por modelação, equivalência de estímulos, discriminações condicionais, escolha de acordo com o modelo, aprendizagem observaciona

Nanostructured Al-ZrAl3 materials consolidated via spark plasma sintering: Evaluation of their mechanical properties

Aluminium based nanostructured materials with additions of 0.5, 1 and 1.5 wt.% of zirconium have been produced and sintered using the spark plasma sintering technique in order to promote the nucleation of ZrAl3 platelets. The mechanical behaviour of all these nanocomposites was determined by means of the Small Punch Test. Zirconium additions significantly decrease the mechanical properties of these products when sintering time at the sintering temperature (625 °C) is short (3 min). Nevertheless, when the sintering time increases to 1 h (intermetallic crystallization), the zirconium additions show the expected effect: the stiffness and the yield strength increase while ductility and toughness decrease. The maximum load increases until a 0.5 wt.% Zr is attained and suddenly drops when the Zr content surpasses 1 wt.%. © 2012 Elsevier B.V. All rights reserved.The authors want to acknowledge the financial support of the Ministerio de Educación y Ciencia (Plan Nacional I+D+i), through the project numbers MEC-04-MAT2004-06992-C02-01 and MAT2008-06879-C03-00.Peer Reviewe

Desarrollo de un Hierro Nodular Bainítico para fabricar Piezas de Equipos de la Construcción

C

A supervisory strategy to improve work performance for lower functioning retarded clients in a sheltered workshop.

A multiple component strategy was investigated for aiding staff responsible for supervising production of lower functioning retarded clients on contract tasks in an institution-based sheltered workshop. The strategy was assessed in a combined multi-element, multiple baseline across groups design with a reversal component. Production performance increased during the production supervisory strategy with all 16 clients, with the range of increase varying from a few percentage points to 150% of baseline production. Both the clients and staff (responsible for conducting the research) preferred working under experimental conditions rather than under baseline conditions which approximated those found in "typical" sheltered workshops

High-chromium (22-34 per cent) Cast Iron Alloys and Their Simulated Behaviour at the Sugar Industry

583-588The good results obtained by cast iron with Cr and Cr- Ni investigated in the making of part for pumping equipment in sugar cane industry are given. Cast iron alloy coupons were prepared in order to study their hardness, resilience, corrosion resistance, and wear-out behaviour by means of simulating the conditions found at the sugar industry processes. Microstructural characterisation of alloys was made by scanning electron microscopy (SEM), and the electrochemical trials in order to assess corrosion susceptibility were performed with a specific sugar solution. The behaviour of alloys to wear-out and corrosion depends mainly on the chemical composition and effect of the alloying elements the formation of carbides during soliditication, and the presence of impurities and inclusions at a surface level. The results obtained in this study made possible the selection of better alloys, which can be employed at the sugar industry such as 0.78 C-33 , 5 Cr-7.7 Ni which have a high-chromium content. This material implies a considerable economic saving for sugar industry