8 resultados para Long memory stochastic process
em Universidade Federal do Rio Grande do Norte(UFRN)
Resumo:
This research investigated the dance piece Caldo da Cana which premiered in João Pessoa-PB, in September 1984. It problematizes theoretical and practical way to make dance history, investigating this possibility through the dance itself. Arises from the fact that the dance has specific characteristics that can not be neglected by the historical account. In this sense, it was initiated by the raising of a theoretical framework that speaks to the indicated issues and unfolds through a field study, which included collecting testimonies from people who participated in the show, documentary research, gathering material traces and finally consists a practical part by transposing elaborated historical knowledge into the body through a creative process, resulting on this moment, in the construction of a duo dance
Resumo:
The seismic method is of extreme importance in geophysics. Mainly associated with oil exploration, this line of research focuses most of all investment in this area. The acquisition, processing and interpretation of seismic data are the parts that instantiate a seismic study. Seismic processing in particular is focused on the imaging that represents the geological structures in subsurface. Seismic processing has evolved significantly in recent decades due to the demands of the oil industry, and also due to the technological advances of hardware that achieved higher storage and digital information processing capabilities, which enabled the development of more sophisticated processing algorithms such as the ones that use of parallel architectures. One of the most important steps in seismic processing is imaging. Migration of seismic data is one of the techniques used for imaging, with the goal of obtaining a seismic section image that represents the geological structures the most accurately and faithfully as possible. The result of migration is a 2D or 3D image which it is possible to identify faults and salt domes among other structures of interest, such as potential hydrocarbon reservoirs. However, a migration fulfilled with quality and accuracy may be a long time consuming process, due to the mathematical algorithm heuristics and the extensive amount of data inputs and outputs involved in this process, which may take days, weeks and even months of uninterrupted execution on the supercomputers, representing large computational and financial costs, that could derail the implementation of these methods. Aiming at performance improvement, this work conducted the core parallelization of a Reverse Time Migration (RTM) algorithm, using the parallel programming model Open Multi-Processing (OpenMP), due to the large computational effort required by this migration technique. Furthermore, analyzes such as speedup, efficiency were performed, and ultimately, the identification of the algorithmic scalability degree with respect to the technological advancement expected by future processors
Resumo:
Memory and anxiety are related phenomena. Several evidences suggest that anxiety is fundamental for learnining and may facilitate or impair the memory formation process depending of the context. The majority of animal studies of anxiety and fear use only males as experimental subjects, while studies with females are rare in the literature. However, the prevalence in phobic and anxiety disorders is greater in women than in men. Moreover, it is known that gender maybe influence benzodiazepine effects, the classic drugs used for anxiety disorders treatment. In this respect, to further investigate if fear/anxiety aspects related to learning in female subjects would contribute to the study of phobic and anxiety disorders and their relationship with learning/memory processes, the present work investigates (a) the effects of benzodiazepine diazepam on female rats performance in a aversive memory task that assess concomitantly anxiety/emotionality, as the interaction between both; (b) the influence of estrous cycle phases of female rats on diazepam effects at aversive memory and anxiety/emotionality, and the interaction between both and (c) the role of hormonal fluctuations during estrous cycle phases in absence of diazepam effects in proestrus, because female rats in this phase received or not mifepristone, the antagonist of progesterone receptor, previously to the diazepam treatment. For this purpose, the plus maze discriminative avoidance task, previously validated for studies of anxiety concomitantly to learning/memory, was used. The apparatus employed is an adaptation of a conventional plus maze, with two opens arms and two closed arms, one of which presenting aversive stimulation (noise and light). The parameters used were: time in non-aversive arm compared to time in aversive and percentage of time in aversive arm on several temporal divisions, in order to evaluate memory; percentage of time in open arms, risk assessment, head dipping and end exploring to evaluate anxiety ; and distance traveled for locomotion. In experiment I, we found anxiolytic effect of diazepam only for 4 mg/kg dose, however the amnestic effect appear at a dose of 2 mg/kg. In second experiment, rats were divided in groups according estrous cycle phase (metaestrus/diestrus, proestrus e estrus). In this experiment, when we considered estrous cycle phase or diazepam treatment, the results did not demonstrate any differences in anxiety/emotionality parameters. The amnestic effects of diazepam occur in female rats in metestrus/diestrus and estrus and is absent in proestrous rats. Proestrous female rats that received mifepristone exhibited the amnestic effect of diazepam and also anxiolytic effects, that it was not previously observed in this dose. The results have demonstrated dissociation of anxiolytic and amnestic diazepam effects, not previously observed in males; the absence of amnestic effect of diazepam in proestrous phase; and the possible role of progesterone in aversive memory over diazepam effect, because the mifepristone, associated with diazepam, caused amnestic effect in proestrus
Resumo:
This research investigated the dance piece Caldo da Cana which premiered in João Pessoa-PB, in September 1984. It problematizes theoretical and practical way to make dance history, investigating this possibility through the dance itself. Arises from the fact that the dance has specific characteristics that can not be neglected by the historical account. In this sense, it was initiated by the raising of a theoretical framework that speaks to the indicated issues and unfolds through a field study, which included collecting testimonies from people who participated in the show, documentary research, gathering material traces and finally consists a practical part by transposing elaborated historical knowledge into the body through a creative process, resulting on this moment, in the construction of a duo dance
Resumo:
This paper deals with the fundamental elements of a curricular proposal aiming at the formation of alphabetizers of young and adults, as long as it concerns the relation between the academic knowledge and that one arising from the classroom experience. The empirical field of the research comes from the work of the teachers responsible for the formation of the alphabetizers of the GerAção Cidadã Program (2004-2005) linked, as an Extension Program, to Federal University of Rio Grande do Norte. Indeed, it tries to understand how these young and adult educators makers figure out the link between the experienced knowledge, which their lives give testimony of, with the scientific knowledge, which they are entitled to mediate in class. This work is funded in the principles of the Collaborative Research, which constitutes a kind of qualitative research. It makes use of procedures supported by qualitative research, especially those ones related to reflexive sessions, as well as to documental researches and semi-structured interviews. These spaces have afforded the group of alphabetizers the opportunity to talk over their practice, not only individually but also collectively, in order to work out contributive proposals having in view changes in the educative actions. As elaborated contributions, we present a discussion about the specificities in the making of educators to EJA, in their differentiated social roles. Reflecting on the experiences of the educators makers, we highlight those elements we regard as essential to the constitution of a formation proposal, like formative times and spaces, dialogue and social memory. The curricular organization is compreneded as part of an enlarged dimension that does not restraint itself to school; rather, it is visualized as a structuring instance that connects different knowledge surpassing community and university. Under this optics, we come to the conclusion that the connection the scientific knowledge establishes with the experienced one, which is immersed in the cultural practices of those who are involved in the formative process, is the basement to a curricular proposal of a formation course destined to educators committed with the need of changing society
Resumo:
In the behavioral paradigm of discriminative avoidance task, both short and long-term memories have been extensively investigated with behavioral and pharmacological approaches. The aim of the present study was to evaluate, using the abovementioned model, the hippocampal expression of zif-268 - a calcium-dependent immediate early gene involved with synaptic plasticity process - throughout several steps of memory formation, such as acquisition, evocation and extiction. The behavioral apparatus consisted of a modified elevaated plus-maze, with their enclosed arms disposed in "L". A pre-exposure to the maze was made with the animal using all arms enclosed, for 30 minutes, followed by training and test, during 10 minutes each. The between sections interval was 24h. During training, aversive stimuli (bright light and loud noise) were actived whenever the animals entered one of the enclosed armas (aversive arm). Memory acquisiton, retention and extinction were evaluated by the percentage of the total time spent exploring the aversive arm. The parameters evaluated (time spent in the arms and total distance traveled) were estimated with an animal tracking software (Anymaze, Stoelting, USA). Learning during training was estimated by the decrease of the time spent exploring the aversive arm. One hour after the beginning of each section, animals were anaesthetized with sodium-thiopental (i.p.) and perfused with 0.9% heparinized saline solution followed by 4% paraformaldehyde. Brains were cryoprotected with 20% sucrose, separeted in three blocks and frozen. The middle block, containing the hippocampus, was sectioned at 20 micro meters in the coronal plane and the resutant sections were submitted to zif-268 immunohistochemistry. Our results show an increased expression of zif-268 in the dentate gyrus (DG) during the evocation and extinction stages. There is a distinct participation of the DG during the memory evocation, but not during its acquisition. Inaddition, all hippocampal regions (CA1, CA3 and DG) presented an increased zif-268 expression during the process of extinction.
Resumo:
The exposure to stressors produces physiological changes of the organism in order to adapt the individual to the environment. Depending on the type, intensity and duration, stress can affect some cognitive functions, particularly processes of learning and memory. Several studies have also proposed that some level of anxiety would be necessary for memory formation. In this context, memories of previously aversive experiences may determine the manner and intensity with which are expressed fear responses, which explains the great interest in analyzing both anxiety and memory in animals. In addition, males and females demonstrate different reactions in relation to stressful stimuli, showing different levels of anxiety and differences in processing of the acquisition, retention and recall of information. Based on this information, the present study aimed to verify the effect of stress on learning, memory and anxiety behavioral parameters in rats exposed at different types of stressors of long duration (seven consecutive days): restraint (4h/day), overcrowding (18h/day) and social isolation (18h/day) in the different phases of the estrous cycle. Our results showed that the stress induced by restraint and social isolation did not cause changes in the acquisition process, but impaired the recall of memory in rats. Furthermore, it is suggested a protective effect of sex hormones on retrieval of aversive memory, since female rats in proestrus or estrus phase, characterized by high estrogen concentrations, showed no aversive memory deficits. Furthermore, despite the increased plasma levels of corticosterone observed in female rats subjected to restraint stress and social isolation, anxiety levels were unaltered, compared to those various stress conditions. Animal models based on psychological and social stress have been extensively discussed in the literature. Correlate behavioral responses, physiological and psychological have contributed in increasing the understanding of stress-induced psychophysiological disorders
Resumo:
Several studies have shown that there is a circadian modulation of explicit memory. This modulation can occur independently in each one of the mnemonic processes. The aim of this study was to evaluate the influence of time of training on short-term memory (STM) and long-term memory (LTM), using a recognition task. Moreover, a possible circadian modulation in retrieving was investigated when this process matched the acquisition hour (time stamp). The chronotype variable was also considered. Fifty-seven undergraduate students aging between 18 and 25 years (21,72 ± 2,14; 28 ♂) participated in this study. In the training phase (acquisition) the subjects heard a ten word list. Following this, they answered a recognition test to evaluate STM and one week later they answered a recognition test to evaluate LTM. In each chronotype, the subjects were divided in groups according to the training hour, part of them in the morning and the other in the afternoon. One week later some of the subjects in each group underwent LTM testing in the morning and others in the afternoon. When the subjects performances were analyzed together, independently of the chronotypes, a training hour effect was found in the LTM. The subjects trained in the afternoon had better performance. No time of day effect was found in the STM and in retrieving from the LTM. However, the morning types who were trained and tested in the same hour had a better performance in the LTM when compared to morning types trained and tested in different hours. This effect did not occur when the other chronotypes were analyzed. The circadian modulation seems to occur at least in two different ways. First, there is a circadian modulation in the acquisition/consolidation processes, with a better performance occuring in the afternoon. Secondly, there is a modulation in the retrieval mnemonic process, called time stamp phenomenon. This phenomenon, that occurred in the morning types, is showed for the first time in humans