23 resultados para Experimental behavior


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This paper examines the notions of illusions and beliefs, discussing some advantages offered by the study of these phenomena based on the concepts of superstitious behavior, superstition and superstitious rules. Among these advantages, the study highlights the possibility of researching these relationships in different levels of analysis, not only at the individual level, focusing on cultural level, this paper presents Cultural Materialism as an anthropological proposal for the consideration of these phenomena on the cultural level and based on adaptive principles, besides it discusses the experimental analysis of cultural practices and points Out how they can help to understand how people in groups behave such as they are being effective in the control of the surrounding environment (when, sometimes, in fact, they are not). The paper offers an integrative proposal which makes easier behavior analysts' dialogue with social psychologists and offers some routes from cultural analysis of illusions and beliefs.

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The effect of different propionaldehyde ratios on the properties of bis-GMA-based comonomers and copolymers diluted with propoxylated bis-GMA (CH3bis-GMA) was evaluated. Five experimental comonomers were prepared combining bis-GMA with CH3bis-GMA and propionaldehyde at 0, 2, 8, 16, 24 mol%. Light polymerization was effected with the use of 0.2 wt. (%) each of camphorquinone and N,N-dimethyl-p-toluidine. Resin degrees of conversion (%DC) were evaluated by FT-IR spectrophotometry and Tg by Differential Scanning Calorimeter. Complex viscosity (η*), the effect of temperature on η*, and Microhardness (H) for dry and wet samples were also determined. Data were analyzed by Student's t-test, one-way ANOVA and Tukey-Kramer test (α = 0.05). The group with 24 mol% additive had a significant increase in %DC and H, and the lowest comonomer Tg and η*. No remarkable variation was noted in copolymers Tg s. All resins presented Newtonian behavior of viscosity, which linearly decreased with increased temperature. The η* decreased sigmoidally as the additive ratio increased.

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This study investigated the effects of perinatal cadmium exposure on sexual behavior, organ weight, and testosterone levels in adult rats. We examined whether immediate postpartum testosterone administration is able to reverse the toxic effects of the metal. Forty pregnant Wistar rats were divided into three groups: 1) control, 2) 10 mg kg-1 cadmium chloride per day, and 3) 20 mg kg-1 cadmium chloride per day. These dams were treated on gestational days 18 and 21 and from lactation 1 to 7. Immediately after birth, half of the offspring from the experimental and control groups received 50 μl (i.p.) of 0.2% testosterone. Male sexual behavior, histological analysis and weight of organs as well as serum testosterone levels were assessed. Results showed that both cadmium doses disrupted sexual behavior in male rats, and postnatal treatment with testosterone reversed the toxic effects of 10 mg kg-1 cadmium and attenuated the effects of 20 mg kg-1 cadmium. Body weight and absolute testis, epididymis, and seminal vesicle weight were decreased by the higher cadmium dose, and testosterone supplementation did not reverse these effects. Serum testosterone levels were unaffected by both cadmium doses. No histological changes were detected in all organs analyzed. Maternal cadmium exposure effects in sexual parameters of male rat offspring were explained by the altered masculinization of the hypothalamus. We suggest that cadmium damaged cerebral sexual differentiation by its actions as an endocrine disruptor and supported by the changes discretely observed from early life during sexual development to adult life, reflected by sexual behavior. Testosterone supplementation after birth reversed some crucial parameters directly related to sexual behavior.

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This paper is the first part of an extensive work focusing the technological development of steel fiber reinforced concrete pipes (FRCP). Here is presented and discussed the experimental campaign focusing the test procedure and the mechanical behavior obtained for each of the dosages of fiber used. In the second part ("Steel fiber reinforced concrete pipes. Part 2: Numerical model to simulate the crushing test"), the aspects of FRCP numerical modeling are presented and analyzed using the same experimental results in order to be validated. This study was carried out trying to reduce some uncertainties related to FRCP performance and provide a better condition to the use of these components. In this respect, an experimental study was carried out using sewage concrete pipes in full scale as specimens. The diameter of the specimens was 600 mm, and they had a length of 2500 mm. The pipes were reinforced with traditional bars and different contents of steel fibers in order to compare their performance through the crushing test. Two test procedures were used in that sense. In the 1st Series, the diameter displacement was monitored by the use of two LVDTs positioned at both extremities of the pipes. In the 2nd Series, just one LVDT is positioned at the spigot. The results shown a more rigidity response of the pipe during tests when the displacements were measured at the enlarged section of the socket. The fiber reinforcement was very effective, especially when low level of displacement was imposed to the FRCP. At this condition, the steel fibers showed an equivalent performance to superior class pipes made with traditional reinforced. The fiber content of 40 kg/m3 provided a hardening behavior for the FRCP, and could be considered as equivalent to the critical volume in this condition.

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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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Biological membranes are constituted from lipid bilayers and proteins. Investigation of protein-membrane interaction, essential for biological function of cells, must rest upon solid knowledge of lipid bilayer behavior. Thus, extensive studies of an experimental model for membranes, lipid bilayers in water solution, have been undertaken in the last decades. These systems present structural, thermal and electrical properties which depend on temperature, ionic strength or concentration. In this talk, we shall discuss statistical models for lipid bilayers, as well as the relation between their properties and results for properties of lipid dispersions investigated by the laboratories supervised by Teresa Lamy (IF-USP) and Amando Ito (FFCL-USP).

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Nerve-related complications have been frequently reported in dental procedures, and a very frequent type of occurrence involves the inferior alveolar nerve (IAN). The nerve injury in humans often results in persistent pain accompanied by allodynia and hyperalgesia. In this investigation, we used an experimental IAN injury in rats, which was induced by a Crile hemostatic clamp, to evaluate the effects of laser therapy on nerve repair. We also studied the nociceptive behavior (von Frey hair test) before and after the injury and the behavioral effects of treatment with laser therapy (emitting a wavelength of 904 nm, output power of 70 Wpk, a spot area of *0.1 cm2, frequency of 9500 Hz, pulse time 60 ns and an energy density of 6 J/cm2). As neurotrophins are essential for the process of nerve regeneration, we used immunoblotting techniques to preliminarily examine the effects of laser therapy on the expression of nerve growth factor (NGF) and brainderived neurotrophic factor (BDNF). The injured animals treated with laser exhibited an improved nociceptive behavior. In irradiated animals, there was an enhanced expression of NGF (53%) and a decreased BDNF expression (40%) after laser therapy. These results indicate that BDNF plays a locally crucial role in pain-related behavior development after IAN injury, increasing after lesions (in parallel to the installation of pain behavior) and decreasing with laser therapy (in parallel to the improvement of pain behavior). On the other hand, NGF probably contributes to the repair of nerve tissue, in addition to improving the pain-related behavior.

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The reduction of friction and wear in systems presenting metal-to-metal contacts, as in several mechanical components, represents a traditional challenge in tribology. In this context, this work presents a computational study based on the linear Archard's wear law and finite element modeling (FEM), in order to analyze unlubricated sliding wear observed in typical pin on disc tests. Such modeling was developed using finite element software Abaqus® with 3-D deformable geometries and elastic–plastic material behavior for the contact surfaces. Archard's wear model was implemented into a FORTRAN user subroutine (UMESHMOTION) in order to describe sliding wear. Modeling of debris and oxide formation mechanisms was taken into account by the use of a global wear coefficient obtained from experimental measurements. Such implementation considers an incremental computation for surface wear based on the nodal displacements by means of adaptive mesh tools that rearrange local nodal positions. In this way, the worn track was obtained and new surface profile is integrated for mass loss assessments. This work also presents experimental pin on disc tests with AISI 4140 pins on rotating AISI H13 discs with normal loads of 10, 35, 70 and 140 N, which represent, respectively, mild, transition and severe wear regimes, at sliding speed of 0.1 m/s. Numerical and experimental results were compared in terms of wear rate and friction coefficient. Furthermore, in the numerical simulation the stress field distribution and changes in the surface profile across the worn track of the disc were analyzed. The applied numerical formulation has shown to be more appropriate to predict mild wear regime than severe regime, especially due to the shorter running-in period observed in lower loads that characterizes this kind of regime.