869 resultados para [JEL:D11] Microeconomics - Household Behavior and Family Economics - Consumer Economics: Theory


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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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We analyze new results on a magnetically levitated body (a block including a magnet whose bottom pole is set in such a way as to repel the upper pole of a magnetic base) excited by a non-ideal energy source (an unbalanced electric motor of limited power supply). These new results are related to the jump phenomena and increase of power required of such sources near resonance are manifestations of a non-ideal system and they are referred as the Sommerfeld effect, which emulates an energy sink. In this work, we also discuss control strategies to be applied to this system, in resonance conditions, in order to decrease its vibration amplitude and avoiding this apparent energy sink.

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This dissertation studies environmental regulation issues in the hog production industry as well as forces behind the reorganization of the industry during the past two decades. Federal and State-level environmental regulations imposed on U.S. hog production during the year 2003 are examined in Chapter 1. Based on the number of regulations passed by the Federal government and states, the 2003 regulatory index is constructed. The regulatory stringency index suggests that state-level regulations vary across states and have increased over the years. In addition, state-level regulations are more stringent than federal regulations. Chapter 2 develops an empirically implementable theoretical model which allows us to investigate the long-run effects of environmental regulations on the U.S. hog industry. Hog feeding operations (HFOs) are divided into large feeding operations (LHFOs) and small feeding operations (SHFOs). The impact of the presence of a large number of LHFOs on the entry and exit of CHFOs is also examined. Results of this study suggest that: Increased state-level regulation stringency significantly lowers the output of SHFOs; increased state-level regulation stringency significantly lowers the output of LHFOs; increased state-level regulation stringency significantly lowers the number of SHFOs; SHFO output rises significantly in states that have a greater number of LHFOs; LHFO output rises significantly in states that have a greater number of LHFOs; the number of SHFOs significantly increases in states that have a greater numbers of LHFOs; regulation increases the average SHFO size; and regulation decreases the average LHFO size. Chapter 3 examines the importance of input availability, market attractiveness, agglomeration economies and environmental regulations on the reorganization of U.S. hog production for a panel of 22 U.S. hog producing states which include, Northern states, Southern states and Midwest states for the period 1994-2006. Results from this study suggest that: Hog production in a state is positively affected by hog production in a nearby state, confirming the presence of agglomeration economies; Environmental regulations and high corn price have negative effects on state-level U.S. hog production; High hog prices, and favorable labor cost, and land values attract hog production; and transportation cost has no effect on hog production. Advisors: Azzeddine Azzam and Karina Schoengold

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Family estate planning is a phrase used to describe the acquisition, enjoyment, and disposition of the family's possessions. The estate plan organizes the resources of the family of an effort to provide for the present and future needs of the family and other heirs. A plan which is started early usually has a better chance of accomplishing the desired objectives.

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It has been known for centuries that light (photoperiod) is possibly the major environmental stimuli affecting bird behavior and physiology. The length of the light period stimulates the breeding cycle, migration, fat deposition, and molt in most species of birds. Therefore, it is only natural that one would think of using light as a means of bird control. In fact, light has already been used as a bird control; flood-light traps have been used to trap blackbirds (Meanley 1971); Meanley states that 2000-W search lights have been used to alleviate depredation by ducks in rice fields. Pulsing light is already used on aircraft, aircraft hangers and high towers as a means of detourinq birds (Schaefer, 1968). With some positive results already obtained with light as a bird control, the next step is to see if a better light source (the laser) might not have a greater effect. The laser is basically an intense and coherent light with extreme directivity and, thus, might have greater influence on a bird’s behavioral and physiological responses.

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How do capuchin monkeys learn to use stones to crack open nuts? Perception-action theory posits that individuals explore producing varying spatial and force relations among objects and surfaces, thereby learning about affordances of such relations and how to produce them. Such learning supports the discovery of tool use. We present longitudinal developmental data from semifree-ranging tufted capuchin monkeys (Cebus apella) to evaluate predictions arising from Perception-action theory linking manipulative development and the onset of tool-using. Percussive actions bringing an object into contact with a surface appeared within the first year of life. Most infants readily struck nuts and other objects against stones or other surfaces from 6 months of age, but percussive actions alone were not sufficient to produce nut-cracking sequences. Placing the nut on the anvil surface and then releasing it, so that it could be struck with a stone, was the last element necessary for nut-cracking to appear in capuchins. Young chimpanzees may face a different challenge in learning to crack nuts: they readily place objects on surfaces and release them, but rarely vigorously strike objects against surfaces or other objects. Thus the challenges facing the two species in developing the same behavior (nut-cracking using a stone hammer and an anvil) may be quite different. Capuchins must inhibit a strong bias to hold nuts so that they can release them; chimpanzees must generate a percussive action rather than a gentle placing action. Generating the right actions may be as challenging as achieving the right sequence of actions in both species. Our analysis suggests a new direction for studies of social influence on young primates learning sequences of actions involving manipulation of objects in relation to surfaces.

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Restricted stimulus control refers to discrimination learning with atypical limitations in the range of controlling stimuli or stimulus features In the study reported here 4 normally capable individuals and 10 individuals with Intellectual disabilities (ID) performed two-sample delayed matching to sample Sample stimulus observing was recorded with an eye tracking apparatus High accuracy scores indicated stimulus control by both sample stimuli for the 4 nondisabled participants and 4 participants with ID and eye tracking data showed reliable observing of all stimuli Intermediate accuracy scores indicated restricted stimulus control for the remaining 6 participants Their eye tracking data showed that errors were related to failures to observe sample stimuli and relatively brief observing durations Five of these participants were then given interventions designed to improve observing behavior For 4 participants the interventions resulted initially in elimination of observing failures increased observing durations and Increased accuracy For 2 of these participants contingencies sufficient to maintain adequate observing were not always sufficient to maintain high accuracy subsequent procedure modifications restored It however For the 5th participant initial improvements in observing were not accompanied by improved accuracy in apparent Instance of observing without attending accuracy improved only after an additional intervention that imposed contingencies on observing behavior Thus interventions that control observing behavior seem necessary but may not always be sufficient for the remediation of restricted stimulus control

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The main constituents of red mud produced in Aluminio city (S.P., Brazil) are iron, aluminum, and silicon oxides. It has been determined that the average particle diameter for this red mud is between 0.05 and 0.002 mm. It is observed that a decrease in the percentage of smaller particles occurs at temperatures greater than 400 degrees C. This observation corresponds with the thermal analysis and X-ray diffraction (XRD) data, which illustrate the phase transition of goethite to hematite. A 10% mass loss is observed in the thermal analysis patterns due to the hydroxide-oxide phase transitions of iron (primary phase transition) and aluminum (to a lesser extent). The disappearance and appearance of the different phases of iron and aluminum confirms the decomposition reactions proposed by the thermal analysis data. This Brazilian red mud has been classified as mesoporous at all temperatures except between 400 and 500 degrees C where the classification changes to micro/mesoporous.

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The microstructural behavior of industrial standardized cocoa butter samples and cocoa butter samples from three different Brazilian states is compared. The cocoa butters were characterized by their microstructural patterns, crystallization kinetics and polymorphic habits. The evaluation of these parameters aided in establishing relationships between the chemical compositions and crystallization behavior of the samples, as well as differentiating them in terms of technological and industrial potential for use in tropical regions.

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We investigate the nonequilibrium roughening transition of a one-dimensional restricted solid-on-solid model by directly sampling the stationary probability density of a suitable order parameter as the surface adsorption rate varies. The shapes of the probability density histograms suggest a typical Ginzburg-Landau scenario for the phase transition of the model, and estimates of the "magnetic" exponent seem to confirm its mean-field critical behavior. We also found that the flipping times between the metastable phases of the model scale exponentially with the system size, signaling the breaking of ergodicity in the thermodynamic limit. Incidentally, we discovered that a closely related model not considered before also displays a phase transition with the same critical behavior as the original model. Our results support the usefulness of off-critical histogram techniques in the investigation of nonequilibrium phase transitions. We also briefly discuss in the appendix a good and simple pseudo-random number generator used in our simulations.

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Introduction: The identification of stages of dietary change and the factors affecting food choices can direct more effective nutritional intervention against coronary heart disease progression. Objective: Identify the stages of change of eating behavior and its relation with nutritional status, food consumption and previous cardiovascular events in patients who underwent coronary angioplasty. Methods: A cross-sectional study with 200 hospitalized patients from a specialized cardiology hospital, after elective coronary angioplasty. They were applied an algorithm that identifies the provision of change of eating habits for a healthier pattern. Variables measured were stages of change of eating behavior, nutritional status, food consumption and cardiovascular events (previous myocardial infarction or angioplasty). It was realized comparison of averages by analysis of variance or Student's test and Chi-square test for qualitative variables. Value of significance was taken at 5%. Results: The patients were classified in the following stages: 36% maintenance, 26% preparation, 17% precontemplation, 12% action and 9% contemplation. It was observed higher cardiovascular events in maintenance/action group (p = 0.04), higher consumption of calories (p = 0.04), meat/eggs (p = 0.01) and sweets (p = 0.03) in preparation stage, comparing to maintenance group, and no association between nutritional status and stages of change (p = 0.13), although 62% of the individuals in maintenance stage were overweight. Conclusions: This work contributed to identifying the stages of change and conditions that favor changes in eating pattern. Even patients that classified themselves into the maintenance stage need to adjust their eating habits in order to reach a healthy weight.

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Abstract Background Neonatal STZ treatment induces a state of mild hyperglycemia in adult rats that disrupts metabolism and maternal/fetal interactions. The aim of this study was investigate the effect of neonatal STZ treatment on the physical development, behavior, and reproductive function of female Wistar rats from infancy to adulthood. Methods At birth, litters were assigned either to a Control (subcutaneous (s.c.) citrate buffer, n = 10) or STZ group, (streptozotocin (STZ) - 100 mg/kg-sc, n = 6). Blood glucose levels were measured on postnatal days (PND) 35, 84 and 120. In Experiment 1 body weight, length and the appearance of developmental milestones such as eye and vaginal opening were monitored. To assess the relative contribution of the initial and long term effects of STZ treatment this group was subdivided based on blood glucose levels recorded on PND 120: STZ hyperglycemic (between 120 and 300 mg/dl) and STZ normoglycemic (under 120 mg/dl). Behavioral activity was assessed in an open field on PND 21 and 75. In Experiment 2 estrous cyclicity, sexual behavior and circulating gonadotropin, ovarian steroid, and insulin levels were compared between control and STZ-hyperglycemic rats. In all measures the litter was the experimental unit. Parametric data were analyzed using one-way or, where appropriate, two-way ANOVA and significant effects were investigated using Tukey’s post hoc test. Fisher’s exact test was employed when data did not satisfy the assumption of normality e.g. presence of urine and fecal boli on the open field between groups. Statistical significance was set at p < 0.05 for all data. Results As expected neonatal STZ treatment caused hyperglycemia and hypoinsulinemia in adulthood. STZ-treated pups also showed a temporary reduction in growth rate that probably reflected the early loss of circulating insulin. Hyperglycemic rats also exhibited a reduction in locomotor and exploratory behavior in the open field. Mild hyperglycemia did not impair gonadotropin levels or estrous cylicity but ovarian steroid concentrations were altered. Conclusions In female Wistar rats, neonatal STZ treatment impairs growth in infancy and results in mild hyperglycemia/hypoinsulinemia in adulthood that is associated with changes in the response to a novel environment and altered ovarian steroid hormone levels.

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Adolescence has been linked to greater risk-taking and novelty-seeking behavior and a higher prevalence of drug abuse and risk of relapse. Decreases in cyclic adenosine monophosphate response element binding protein (CREB) and phosphorylated CREB (pCREB) have been reported after repeated cocaine administration in animal models. We compared the behavioral effects of cocaine and abstinence in adolescent and adult mice and investigated possible age-related differences in CREB and pCREB levels. Adolescent and adult male Swiss mice received one daily injection of saline or cocaine (10 mg/kg, i.p.) for 8 days. On day 9, the mice received a saline injection to evaluate possible environmental conditioning. After 9 days of withdrawal, the mice were tested in the elevated plus maze to evaluate anxiety-like behavior. Twelve days after the last saline/cocaine injection, the mice received a challenge injection of either cocaine or saline, and locomotor activity was assessed. One hour after the last injection, the brains were extracted, and CREB and pCREB levels were evaluated using Western blot in the prefrontal cortex (PFC) and hippocampus. The cocaine-pretreated mice during adolescence exhibited a greater magnitude of the expression of behavioral sensitization and greater cocaine withdrawal-induced anxiety-like behavior compared with the control group. Significant increases in CREB levels in the PFC and hippocampus and pCREB in the hippocampus were observed in cocaine-abstinent animals compared with the animals treated with cocaine in adulthood. Interestingly, significant negative correlations were observed between cocaine sensitization and CREB levels in both regions. These results suggest that the behavioral and neurochemical consequences of psychoactive substances in a still-developing nervous system can be more severe than in an already mature nervous system