1,720,958 research outputs found
Variação circadiana na habituação da resposta exploratoria a estimulos sonoros em pombos (Columba livia), submetidos a condições de claro-escuro e de claro constante
No full textOrientador : Elenice A. de Moraes FerrariDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de BiologiaResumo: Este trabalho analisou a habituação a sons no contexto da organização temporal do comportamento. O processo de habituação da resposta exploratória ao som foi analisado em três experimentos. O objetivo principal desses experimentos foi a análise dessa resposta em função do horário das sessões de habituação, i.e., matutinas ou vespertinas Os experimentos diferiram quanto aos ciclos de iluminação aos quais pombos adultos foram expostos: ciclo claro-escuro de 12:12h, no Experimento 1; claro continuo, no Experimento 2; e dois dias de claro continuo, interposto a um ciclo claro-escuro de 12:12h, no Experimento 3. Os três experimentos foram igualados quanto aos horários de teste. Os testes matutinos foram realizados às 7:30h, uma hora após o acender da luz, e às 19:30h. uma hora após o desligar da luz. Os pombos foram submetidos a apresentações de um som de 1000-Hz, 83-dB, 1s (estimulo A), a cada 30 s, até habituação das respostas exploratórias ou até um máximo de 100 estimulos, quando o critério de aprendizagem não era observado O critério de aprendizagem estabelecia a ocorrência de 10 estimulos sem o registro de respostas exploratórias. Uma segunda sessão de habituação, com a apresentação de um som de 500-Hz, 85-dB, 1s (estimulo B>, foi realizada 24h depois. O reteste, com a mesma sequência de procedimentos e inversão do horário de teste. foi realizado 18 dias ap6s a segunda sessão. Os resultados do Experimento 1 mostraram que nos testes noturnos, em comparação com os matutinos. houve um maior número de estimulações até habituação (p(O.05), tanto para o estímulo A quanto para o estimulo B. No Experimento 2 foram observadas diferenças na velocidade da habituação nos testes matutinos e noturnos, apenas nas sessees com o estimulo A (p(0,05). Os pombos expostos a dois dias de iluminação continua antes dos testes do Experimento 3 também mostraram uma di~erença noite-dia embora não significante. O conjunto de dados desses exxperimentos sugerem uma organização temporal dos processos de habituação e colocam questões relativas ao significado biológico da estimulação sonora em condições de claro e de escuro. As diferenças observadas entre os três experimentos também sugerem uma função para a melatonina na regulação desses processos. Os pombos mantidos sob iluminação constante e aqueles que ~oram expostos a dois dias de luz continua antes do teste. provavelmente caracterizados por baixos niveis de melatonina plasmática. mostraram menor velocidade de habituação em comparação com os pombos mantidos em ciclo claroescuro. Os baixos níveis de melatonina poderiam atuar no sentido de uma facilitação da habituação. Também foi argumentado um possivel efeito de estresse devido à exposição a dois dias de luz continua. Nesta condição provavelmente não haveria tempo suficiente para adaptações à nova situação de iluminação. A caracterização precisa dessas diferenças noite-dia na habituação ao som como expressão de um ritmo circadiano necessita ainda de outros estudosAbstract: The present work investigated habituation learning to acoustic stimulation in the context of temporal organization of behavior. The process of habituation of the exploratory responses to sound was analvsed in three experiments. The main purpose of these experiments was the analysis of these responses as function of the time of habituation sessions, i.e., mornins or nisht tests. The experiments differed in relation to the light cycles to which adult pigeons were exposed : 12:12h light-dark cycle in Experiment 1; continuous ilumination in Experiment 2 and twodays of continuous ilumination interposedto a 12:12 light-dark cycle, in Experiment3. Time for testins was matched for the three experimentswith morning tests at 7:30 a.m., one hour after light onset. and night tests at 7:30 p.m., one hour after turn out of light. Piseons were exposed to 1000-Hz.83-dB. ls sound (stimulus A) at 30 seconds intervals until habituation of the exploratory and startle response or until a maximum of 100 stimulus when the learning criterion was not observed. The learnins criterionwas 10 trials without the occurrence of these responses. Twenty-fourhours after habituation to stimulus A the birds were tested with a SOO-Hz, 8S-dB, 1s sound (stimulus B). Retesting. with the same sequence of proceduresbut reversal of the time of test was carried out 18 days after stimulus B habituation. Results from Experiment 1 showed an increased number of habituation trials in nocturnal (p(0,05) as compared to the morning tests for both stimulus A and B. The number of trials until habituation in the Experiment 2 showed differences between morning-night test onlv for stimulus A session. Pigeons exposed to two-davs Df continuous ilumination in Experiment 3 also showed a morning-night difference. although it was not significant. Taken together the data from these experiments suggest one temporal organization of the habituation learning processes and raises issues concerning the biological meaning of sound stimulation in light and dark environmental conditions. The differences observed between the three experiments also sugsest a role for the melatonin hormone in these processes. Pigeons maintained under continuous lisht or exposed to two-days of continuous il1umination prior to tests. which were probably characterized by decreased levels of melatonin, showed facilitation of habituationwhen compared to pigeons maintained under light-darkcycle. The lower levels of melatonin may act toward a facilitation of habituation. lt was also arsued a possible stress variable due to exposition to two-days ofcontinuous lisht. In this condition the animaIs probablv did not have enough time for adaptation to the new situation of constant light. Further studies are necessary for a precise characterization of those morning-night differences in habituation to sound as expression of a circadian rhvthmiticyMestradoFisiologiaMestre em Ciências Biológica
Modelação temporal de processos de aprendizagem : Implicações praticas e teoricas
No full textOrientador: Elenice A. de Moraes Ferrari, Fred W. TurekTese (doutorado) - Universidade Estadual de Campinas, Instituto de BiologiaResumo: Estudos da variação temporal de processos de aprendizagem e memória são relativamente escassos e inconsistentes, fundamentalmente, devido à falta de uma padronização dos métodos utilizados e especificação dos tipos de controles necessários, que permitam isolar componentes temporais endógenos da aprendizagem propriamente dita. Assim, no presente trabalho discutimos as dificuldades deste tipo de estudo e sugerimos estratégias que poderiam ajudar a controlar alguns dos fatores mascaradores. Foram realizados três estudos tentando aplicar algumas destas estratégias. No primeiro, analisamos o efeito da hora do dia na habituação a um contexto novo em camundongos, quantificando o comportamento ambulatório por meio de observação direta. Em condições de claroescuro um ritmo diurno foi detectado, porém nenhum efeito temporal foi observado em animais submetidos a um fotoperíodo esqueleto, situação em que se evita os efeitos mascaradores de um ciclo claro-escuro. Estes resultados demonstram que o ciclo de iluminação pode alterar significativamente a resposta a um contexto, reafirmando a necessidade de um controle preciso desta condição externa. Em estudos de ritmicidade de aprendizagem, devido à elevada freqüência de amostragem necessária e à necessidade de testes em horários pouco convenientes, a automatização da medida comportamental resulta indispensável. Assim, no segundo estudo foi validado um equipamento computadorizado para a medida do comportamento de imobilização em situações de condicionamento aversivo. As medidas comportamentais obtidas por este método automático mostraram uma elevada correlação com as medidas obtidas por observação direta. Conseqüentemente, este sistema foi utilizado no terceiro estudo onde se analisou o condicionamento aversivo durante as fases de atividade e de inatividade de camundongos submetidos a um fotoperíodo esqueleto. Uma diferença significativa entre os testes matutinos e os testes vespertinos foi detectada na expressão e extinção do condicionamento aversivo a um contexto, enquanto que nenhum efeito temporal foi observado no condicionamento aversivo a um som. O fato de que estes dois tipos de aprendizagens envolvem estruturas neurais diferentes sugere que o relógio biológico estaria tendo um efeito modulatório nas vias responsáveis pelo condicionamento a um contextoAbstract: Studies that analyze a temporal variation in learning and memory processes are relatively scattered and inconsistent, mainly due to the lack of systematic methods and specifications of the necessary controls that would allow the dissection of a temporal component in the learning process per se. Here we analyze the difficulties of this kind of study and suggest a few strategies that could help control some of the masking factors. Three studies were performed applying some of these strategies. In the first study we analyzed habituation to a novel environment in mice by quantifying ambulation in an open field through direct observation. Mice submitted to a light-dark cycle showed a
diurnal rhythm in learning however, no temporal effect was observed in animals submitted to a skeleton photoperiod (tw015-minute bright light pulses separated by 12 h of green dim light). Under these conditions the masking effects of a light-dark cyc1e are avoided. These results demonstrate that the response to a novel environment is strongly affected by the illumination cycle, thus reinforcing the need for precise control and specification of this condition. When analyzing learning at different times of the day automation of behavioral sCO1:ing becomes essential due to the need for high frequency in data collection and testing which occurs around the clock. Therefore, a second study was performed where a computer-assisted system for scoring freezing behavior in mice during fear conditioning situations was validated. The computer measures obtained during fear conditioning tests showed high correlations with hand-scored freezing. Consequently, this data collection system was used in a third study where fear conditioning was analyzed during the active and inactive phases of mice submitted to a skeleton photoperiod. A significant difference in the expression and extinction rate of context-dependent fear conditioning was observed between mice trained and tested in the morning versus the evening. In contrast, no diurnal rhythm was detected for tone-cued fear conditioning. The biological clock may have a modulating effect on the hippocampal-dependent pathway which underlies context fear conditioning and no effect on the hippocampal-independent pathway underlying tone-fear conditioningDoutoradoFisiologiaDoutor em Ciências Biológica
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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