Análise da sobre-reação e sub-reação nos ativos de primeira e segunda lina do mercado acionário brasileiro

The Behavioral Finance develop as it is perceived anomalies in these markets efficient. This fields of study can be grouped into three major groups: heuristic bias, tying the shape and inefficient markets. The present study focuses on issues concerning the heuristics of representativeness and anchoring. This study aimed to identify the then under-reaction and over-reaction, as well as the existence of symmetry in the active first and second line of the Brazilian stock market. For this, it will be use the Fuzzy Logic and the indicators that classify groups studied from the Discriminant Analysis. The highest present, indicator in the period studied, was the Liabilities / Equity, demonstrating the importance of the moment to discriminate the assets to be considered "winners" and "losers." Note that in the MLCX biases over-reaction is concentrated in the period of financial crisis, and in the remaining periods of statistically significant biases, are obtained by sub-reactions. The latter would be in times of moderate levels of uncertainty. In the Small Caps the behavioral responses in 2005 and 2007 occur in reverse to those observed in the Mid-Large Cap. Now in times of crisis would have a marked conservatism while near the end of trading on the Bovespa speaker, accompanied by an increase of negotiations, there is an overreaction by investors. The other heuristics in SMLL occurred at the end of the period studied, this being a under-reaction and the other a over-reaction and the second occurring in a period of financial-economic more positive than the first. As regards the under / over-reactivity in both types, there is detected a predominance of either, which probably be different in the context in MLCX without crisis. For the period in which such phenomena occur in a statistically significant to note that, in most cases, such phenomena occur during the periods for MLCX while in SMLL not only biases are less present as there is no concentration of these at any time . Given the above, it is believed that while detecting the presence of bias behavior at certain times, these do not tend to appear to a specific type or heuristics and while there were some indications of a seasonal pattern in Mid- Large Caps, the same behavior does not seem to be repeated in Small Caps. The tests would then suggest that momentary failures in the Efficient Market Hypothesis when tested in semistrong form as stated by Behavioral Finance. This result confirms the theory by stating that not only rationality, but also human irrationality, is limited because it would act rationally in many circumstances

Relação entre padrão comportamental, estágios do ciclo de muda e atividade de enzimas digestivas proteolíticas em juvenis do camarão marinho Litopenaeus vannamei (Crustacea: Penaeidae)

Shrimp farming in Brazil is a consolidated activity, having brought economical and social gains to several states with the largest production concentrated in the northeast. This fact is also reflected in higher feed intake, necessitating a more efficient feed management. Currently, management techniques already foresee food loss due to molting. In this sense, studies relating shrimp s digestive physiology, molting physiology and behavioral response of shrimp feed can optimize the feed management. Thus, our study aimed to evaluate the behavioral response of the marine shrimp L. vannamei (Crustacea: Penaeidae) in accordance with the stages of moulting cycle and feeding schedules based on higher or lower activity of proteolytic digestive enzymes; also, to investigate the influence of feeding schedule on hepatosomatic index and non-specific and specific protease activity (trypsin). Experiments were carried out at the Laboratory of Shrimp Behavioral Studies at UFRN in partnership with the Laboratory of Enzimology UFPE. Juveniles of L. vannamei weighting 5.25 g (+ 0.25 g) were kept in aquaria at a density of 33 shrimp m -2. In the first experiment, shrimp were fed in the light phase or in the dark phase for 8 days; in the ninth day, the animals were observed for 15 minutes every hour during the 12 hours of each phase of the photoperiod. We recorded the frequency of inactivity, exploration, food intake, burrowing, swimming and crawling behavior. At the end of the 12th observation session, the shrimp were sacrified and classified by the method of setogenesis in the molt cycle stages A, B, C, D0, D1, D2 or D3. We found that the shrimp in A stage show high levels of inactivity. Moreover, the frequency of food intake was very low. The shrimp in D3 stage also had low food intake and high inactivity associated with elevated frequencies of burrowing. In the second experiment, shrimp were kept in physiological acclimation to experimental conditions for 28 days, distributed in 12 treatments in the light phase and 12 treatments in the dark phase. In the end, the animals were sacrified and dissected to assess non-specific and specific protease activity (trypsin) activity. In general, these parameters did not vary among animals fed in the light phase and those fed in the dark phase. However, significant differences were found in the activity of specific and nonspecific proteases in relation to food treatment. In the light phase, the major proteolytic activities converged to 10 hours after the start of the light phase, while the lowest activities converged to 6 hours after the beginning of this phase. In the dark phase, the highest enzyme activity converged to 12 hours after the onset of phase, while the lowest activities converged to 3 hours after the onset of phase. In the third experiment, we sought to evaluate the behavioral responses of shrimp in relation to dietary treatments based on higher or lower activity of proteolytic enzymes, considering the results of the second experiment. The behavioral categories observed were the same as the ones in the first experiment, with observations of 30 minutes (15min before and 15min after food supply). We found variation in behavioral responses as a function of the treatments, with greater intake of food in shrimp fed during the period of greatest activity of proteolytic enzymes, in the light phase. Thus we see that periodic events associated with the shrimp s physiology interfere in their behavioral responses, revealing situations that are more adjustable to the provision of food, and consequently optimizing feeding management

Comportamento do camarão de água doce macrobrachium rosenbergii (De Man, 1879) em cultivos misto e monossexo

Understanding the behavioral activities of freshwater shrimp in captivity is of paramount importance for the appropriate management of the species. In Brazil, the shrimp Macrobrachium rosenbergii is currently the most widely used species in the freshwater shrimp culture due to its high potential for cultivation and good market acceptance. Thus, the present study aimed to describe and characterize the behavioral activities of M. rosenbergii in monosex and in mixed (male and female) (manuscript 1, 2 and 3) populations and the growth performance of this species in restrictive feeding conditions and in different feeding management (manuscript 4 and 5, respectively) . Juvenile and adult shrimps were collected from ponds of the Aquaculture Station - Unidade Especializada em Ciências Agrárias - Universidade Federal do Rio Grande do Norte (UFRN), Macaíba/RN and then transferred to the Laboratório de Estudos do Comportamento do Camarão LECC (Laboratory for Shrimp Behavioral Studies) of the Universidade Federal do Rio Grande do Norte (UFRN). For each treatment , eight aquaria of 250 L (50 cm x 50 cm x 100 cm) were used in a closed recirculating water system with artificial lighting, constant aeration , continuous filtration through a biochemical and biological filter (canister filter), and fine sand as substrate . The water quality was monitored daily. The lab consisted of two rooms with artificial lighting system , controlled by a timer with dark / light cycle of 12:12 h . In manuscript 1, the behavioral categories of the species were presented through an ethogram, which described 31 behaviors, subdivided into general and agonistic behaviors. Manuscript 2 compared the behavioral profile of shrimps in male and in female monosex and mixed populations over 24 hours in laboratory. In three types (mixed, male monosex and female monosex) of populations during the light and dark phases of the 24 hour cycle, the shrimps showed higher occurrence of cleaning behavior. Manuscript 3 examined the influence of the color of the shelter on the frequency of its use and behavioral activities of shrimp in mixed, in male monosex and in female monosex populations over 24 hours. We observed that the shrimp M. rosenbergii burrow more frequently during the light phase in male monosex and mixed populations; they also tend to choose the black shelters. Female monosex populations tend to use red and orange shelters. In manuscript 4, we evaluated in laboratory the behavioral activities and growth performance of juvenile shrimps under food restriction. We observed that a mild food restriction may be used since there is no loss concerning the growth of the animals; feeding management on alternate days , compared to daily management can be financially productive both reducing labor costs and reducing the amount of feed used . Manuscript 5 evaluated the behavior of shrimps in monosex and in mixed populations, as well as the latency of reach the food according to feed offer (tray or food dispersal) . Our results indicate that animals adjust to both types of feed offer food dispersal as much as tray, but they spend more time to reach the feed when it is offered in trays (feeders). Comparing culture types (mixed, male monosex and female monosex), the latency to reach the food was lower for female monosex population. The data obtained in this study demonstrate the importance of identifying different pressures and environmental stimuli on the behavioral responses of this species. This knowledge would support management improvement to optimize the levels of animals‟ welfare, resulting in a better zootecnical performance

Comportamento social de botos-cinza, sotalia guianensis, na praia de Pipa, RN, Brasil: dinâmica, sequência, sincronia e respostas ao turismo de observação

Social behavior of Guiana dolphins, Sotalia guianensis, at Pipa Beach, RN, Brazil: dynamics, sequence, breathing synchrony, and responses to dolphin watching. Social animals form groups that can range from temporary to permanent. Depending on the nature of the social relationships developed between individuals, groups present a particular social organization and the effect of these interactions shapes the activity patterns of these animals. This study investigates: (i) fission-fusion dynamics of Guiana dolphins, through the analysis of three dimensions of the social system (variation in spatial cohesion, variation in size and composition of groups), (ii) sequence, routine and behavioral stability, (iii) breathing intervals in synchronized groups and (iv) behavioral responses of the animals to dolphin watching. Systematic observations of Guiana dolphins were made from a platform located in cliffs about 25 m above sea level that surround Madeiro Bay, Pipa Beach. Sampling occurred from December 2007 to February 2009 between 0600 h and 1600 h, and the groups of Guiana dolphins were investigated according to their size (alone and group) and composition (adults, adults and juveniles, and adults and calves). According to the analysis of fission-fusion dynamics, Guiana dolphin groups frequently changed their composition, modifying their patterns of spatial grouping and cohesion every 20 minutes on average. More than 50% of the individuals maintained a distance of up to 2 m from other group members and new individuals were attracted to the group, especially during feeding, leaving it for foraging. Large groups were more unstable than small, while groups containing only adults were more stable than groups of adults and juveniles. According to the Z-score analysis to investigate the sequence and behavioral routine, lone individuals were more ! .7! ! involved in foraging and feeding, while resting was more common in groups. Foraging and feeding were more common in homogeneous groups (individuals of the same age class), while heterogeneous groups (different age classes) were often involved in socialization, displaying a broader behavioral repertoire. Foraging and resting behavior presented higher stability (continuous duration in minutes) than the other behaviors. The analysis of breathing intervals in synchronized groups showed significant differences depending on type of behavior, composition and area preference. During resting, breathing intervals were of longer duration, and groups with calves showed shorter breathing intervals than groups without calves. Lone individuals also preferred areas called corral , often used for the entrapment of fishes. The Markov chain analysis revealed behavioral changes in the presence of boats, according to the type of group composition. Groups composed of adults presented decreased resting and increased in traveling during the presence of boats. Groups of adults and juveniles showed a massive reduction of socialization, while the behavior transition probability traveling-traveling was higher in groups of adults and calves. In the presence of the boats, stability of resting was reduced by one third of its original duration and traveling more than doubled. The behavioral patterns analyzed are discussed in light of socio-ecological models concerning costs and benefits of proximity between individuals and behavioral optimization. Furthermore, significant changes in behavioral patterns indicate that Guiana dolphins, at Pipa Beach, have suffered the effects of tourism as a result of violation of rules of conduct established for the study area

Efeitos de diferentes tipos estressores sobre a memória e aprendizagem de ratas

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

Indicadores da resposta ao estresse agudo associados com a familiaridade ao ambiente e aos procedimentos de banho e tosa em cães (Canis familiaris) da raça poodle

The stress responses can be parameters used in order to identify the welfare of animals. Behavior parameters can also be regarded as means to identify their relation to stressing situations. In this study, adult male and female poodle dogs, accustomed (group 1) or not (group 2) to the environment of a bath and grooming salon were analyzed through the plasmatic concentration of cortisol, cell counting of the immune system (total leukocytes and percentage of neutrophils and lymphocytes) and through observation of changes in behavior before and after the bath and grooming service. After arriving at the kennel, the dogs were taken to the bath and grooming facility, where they had their blood samples taken and were observed for ten minutes. The subsequent procedures consisted of the bath and grooming services and the collection of another blood samples. The research results were analyzed through non-parametric statistic tests and p < 0.05. Accustomed and non-accustomed dogs presented different hormonal and behavior responses: accustomed dogs presented an increasing of the cortisol level at the second blood samples collection, thus indicating stress towards the aforementioned procedures and presenting behavior responses which can be described as moderated stress. Non-accustomed dogs presented the same cortisol levels in both first and second samples suggesting that they were already reacting to the new environment. Dogs also shown behavioral responses which can be described as acute stress. Both male and female dogs showed similar immunological changes as well as different endocrine and behavioral profiles. Concerning aggression, this study demonstrates that biting the owner can be a predicting behavior of aggression during the bath and grooming service, male dogs were more aggressive than the female, and that males were more reactive to unknown caretaker. The results of this research propose that the familiarization of the animal with the bath and grooming environment and caretaker is important to the welfare of poodle dogs, especially to that of male dogs

Influência dos odores de gato e de cobra no comportamento defensivo e expressão de fos do sistema hipotalâmico de defesa de camundongo

Studies using neuronal tract-tracer in rat have shown that the anterior hypothalamic nucleus, dorsomedial division of the ventromedial nucleus of the hypothalamus and dorsal premammillary nucleus are highly connected. When the rat is exposed to predator or its odor these nuclei have shown a expression of Fos and their lesion reduces defensive behavior against predator. This set of nuclei was named the Hypothalamic Defense System. However, little is known about the response of this system to the odor of different predators or its role in mice. In this work, we exposed Swiss mice to two different predators odor (cat and snake) to verify the Fos expression in the Hypothalamic Defense System, as well as the defensive behaviors displayed. The analysis showed that the mice exposure to cat odor had an increased expression of Fos protein compared to control, while those exposed to snake odor showed no rise in Fos expression, which was corroborated by the behavioral data. Our results indicate that this distinct circuit in mice seems to act differentially to odorous stimuli of different predators, causing distinct behavioral responses of mice and that the odor of snake seems not to be perceived by Swiss mice as a threatening stimulus.

Análise da sobre-reação e sub-reação nos ativos de primeira e segunda linha do mercado acionário brasileiro

The Behavioral Finance develop as it is perceived anomalies in these markets efficient. This fields of study can be grouped into three major groups: heuristic bias, tying the shape and inefficient markets. The present study focuses on issues concerning the heuristics of representativeness and anchoring. This study aimed to identify the then under-reaction and over-reaction, as well as the existence of symmetry in the active first and second line of the Brazilian stock market. For this, it will be use the Fuzzy Logic and the indicators that classify groups studied from the Discriminant Analysis. The highest present, indicator in the period studied, was the Liabilities / Equity, demonstrating the importance of the moment to discriminate the assets to be considered "winners" and "losers." Note that in the MLCX biases over-reaction is concentrated in the period of financial crisis, and in the remaining periods of statistically significant biases, are obtained by sub-reactions. The latter would be in times of moderate levels of uncertainty. In the Small Caps the behavioral responses in 2005 and 2007 occur in reverse to those observed in the Mid-Large Cap. Now in times of crisis would have a marked conservatism while near the end of trading on the Bovespa speaker, accompanied by an increase of negotiations, there is an overreaction by investors. The other heuristics in SMLL occurred at the end of the period studied, this being a under-reaction and the other a over-reaction and the second occurring in a period of financial-economic more positive than the first. As regards the under / over-reactivity in both types, there is detected a predominance of either, which probably be different in the context in MLCX without crisis. For the period in which such phenomena occur in a statistically significant to note that, in most cases, such phenomena occur during the periods for MLCX while in SMLL not only biases are less present as there is no concentration of these at any time . Given the above, it is believed that while detecting the presence of bias behavior at certain times, these do not tend to appear to a specific type or heuristics and while there were some indications of a seasonal pattern in Mid- Large Caps, the same behavior does not seem to be repeated in Small Caps. The tests would then suggest that momentary failures in the Efficient Market Hypothesis when tested in semistrong form as stated by Behavioral Finance. This result confirms the theory by stating that not only rationality, but also human irrationality, is limited because it would act rationally in many circumstances