Increase in Hippocampal Theta Oscillations during Spatial Decision Making

The processing of spatial and mnemonic information is believed to depend on hippocampal theta oscillations (5–12 Hz). However, in rats both the power and the frequency of the theta rhythm are modulated by locomotor activity, which is a major confounding factor when estimating its cognitive correlates. Previous studies have suggested that hippocampal theta oscillations support decision-making processes. In this study, we investigated to what extent spatial decision making modulates hippocampal theta oscillations when controlling for variations in locomotion speed. We recorded local field potentials from the CA1 region of rats while animals had to choose one arm to enter for reward (goal) in a four-arm radial maze. We observed prominent theta oscillations during the decision-making period of the task, which occurred in the center of the maze before animals deliberately ran through an arm toward goal location. In speed-controlled analyses, theta power and frequency were higher during the decision period when compared to either an intertrial delay period (also at the maze center), or to the period of running toward goal location. In addition, theta activity was higher during decision periods preceding correct choices than during decision periods preceding incorrect choices. Altogether, our data support a cognitive function for the hippocampal theta rhythm in spatial decision making

Increased hippocampal excitability and impaired spatial memory function in mice lacking VGLUT2 selectively in neurons defined by tyrosine hydroxylase promoter activity

Three populations of neurons expressing the vesicular glutamate transporter 2 (Vglut2) were recently described in the A10 area of the mouse midbrain, of which two populations were shown to express the gene encoding, the rate-limiting enzyme for catecholamine synthesis, tyrosine hydroxylase (TH).One of these populations (‘‘TH– Vglut2 Class1’’) also expressed the dopamine transporter (DAT) gene while one did not ("TH–Vglut2 Class2"), and the remaining population did not express TH at all ("TH-Vglut2-only"). TH is known to be expressed by a promoter which shows two phases of activation, a transient one early during embryonal development, and a later one which gives rise to stable endogenous expression of the TH gene. The transient phase is, however, not specific to catecholaminergic neurons, a feature taken to advantage here as it enabled Vglut2 gene targeting within all three A10 populations expressing this gene, thus creating a new conditional knockout. These knockout mice showed impairment in spatial memory function. Electrophysiological analyses revealed a profound alteration of oscillatory activity in the CA3 region of the hippocampus. In addition to identifying a novel role for Vglut2 in hippocampus function, this study points to the need for improved genetic tools for targeting of the diversity of subpopulations of the A10 area

Qualidade de vida no trabalho da Emater-RN: validação de um instrumento síntese de pesquisa e diagnóstico

The theoretical recital of the present study it is initiated of the evidence that the work occupies an important space in the man s life in way that the majority of the people works and passes great part of its time inside organizati ons. However, it is verified that the relation between man and work is becoming increasingly disagreement a time that the employees had started to complain work s routines, stress, not use all their potential and inadequate work s conditions. It can be observed by the way of Dejours (1994) studies. Thus, as contribution for the quality of work life s (QWL) studies the research developed here objectified to characterize the public employees quality of work life at EMATER -RN taking as reference an instrumen t of research synthesized from the typical academic literature of the subject. The synthesis of an ampler instrument is a necessity not taken care to the literature that treats on the subject but already perceived by some studies like Moraes et al (1990); Rodrigues (1989); Siqueira & Coleta (1989); Moraes et al (1992); Carvalho & Souza (2003); El -Aouar & Souza (2003) and Mourão, Kilimnick & Fernandes (2005); Adorno, Marques & Borges (2005) amongst others. These studies point out weak points of the existing models in the QWL s literature, as well as they recommend the elaboration of a model more flexible, that contemplates Brazilian cultural characteristics, and that contemplates the entire variable studied in the main existing models. For reach this objectiv e the adopted methodology was characterized as a case study with collected data in qualitative and quantitative way. Questionnaires and comments had been used as sources of evidences. These evidences had been tabulated through of statistical package SPSS ( Statistical Package for Social Science), in which the main technique of multivariate analysis used were the factorial analysis. As for the gotten results, it was verified the grouping of the quality of work life s indicators in 11 factors which are: Work s execution, Individual accomplishment, Work s equity, Relation individual and organization, Work s organization, Adequacy of the remuneration, Relation between head and subordinate, Effectiveness of the communication and the learning, Relation between work and personal life, Participation and Effectiveness of the work processes. Whatever to the characterization of the EMATER -RN s quality of work life it was clearly that to the measure that the satisfaction s evaluation with the QWL in the organization walks to intrinsic factors for extrinsic factors this level of satisfaction goes diminishing what points to the importance to improve these extrinsic factors in the institution. In summary it is possible to conclude that the organization studied has offered a significant set of referring variable to the quality of work life of the individual

A satisfação dos clientes internos e o comprometimento organizacional: um estudo à luz do modelo ASH nas indústrias alimentícias no RN

Currently the organizations are passing for continuous cycles of changes due to necessity of survival in the work market. The administration of the future points a way to the organizations of today and tomorrow, the search of the competitiveness from loyalty and motivation of its staff. Of this form, the model of the Auditoria do Sistema Humano (ASH), developed for Spanish researchers and that now it is being applied in Brazil, contemplates a series of dimensions about Human Resources management quality in the companies and the organizational effectiveness, such as the environment where the company is inserted, the strategies, the organizational drawing, the psychological and psychosocial processes, e the reached results. In this direction, the present research analyzed the factors of job satisfaction and organizational commitment, making, also, a relation of causality between the same ones. The quantitative-descriptive research had as population the employees of twenty three nourishing industries of the State of Rio Grande do Norte (Brazil), registered in the Federacy of the Industries of the state. The collection of the data occurred for the months of October of 2005 and March of 2006, by means of the application of questionnaire of model ASH. The sample was composed for 197 employees, however it was observed presence of five outliers, that they had been excluded from the analysis of the data. To extract the dimensions of the satisfaction and the commitment and identification the factorial analysis was used, with extraction method of principal components, rotation Varimax and normalization Kaiser. The gotten dimensions had been evaluated with the calculation of the coefficient Alpha of Cronbach. The factorial analysis of the pointers of the organizational commitment and identification had extracted ten factors. Of these, four had gotten significance of the analyses inside: affective commitment, values commitment, continuance commitment and necessity commitment. The result of the analysis of the pointers of job satisfaction indicated four factors: extrinsic, motivations, relation with the friends and auto-accomplishment. To deal with the data the relation between job satisfaction and organizational commitment it was used technique of multiple regression. The correlation between commitment and satisfaction was satisfactory, detaching the affective commitment with bigger index of correlation, followed of the affective one

Avaliação do potencial antiinflamatório, anticoagulante e hemorrágico de heparinóides presentes em "Artemia franciscana"

Heparan sulfate (HS) and Heparin (Hep) glycosaminoglycans (GAGs) are heterogeneous and highly charged polysaccharides. HS is structurally related to Hep but is much less substituted with sulfo groups than heparin and has a more varied structure (or sequence). Because of structural similiarities between these two polymers, they have been described together as heparinoids . Both chains bind a variety of proteins and mediate various physiologically important processes including, blood coagulation, cell adhesion and growth factor regulation. Heparinoids with structural characteristics similar to these described from HS and/or Hep from mammalian tissues have been isolated from different species of invertebrates, although only a few heparinoids from unusual sources have been characterized. The present study describes the presence of unusual heparinoids population from Artemia franciscana, isolated after proteolysis and fractionation by ion exchange resin and named, F-3.0M. The study model in vivo were hemostasis (rat tail scarification) and inflamatoty activity. The tests in vitro were used for coagulations assays (PT and APTT). The analyse of the heparinoids eluted with 3,0M NaCl showed electrophoretic migration in different buffer systems a single band with a behaviour intermediate between those of mammalian HEP and HS. The main products obtained from Artemia heparinoids after enzymatic degradation with heparitinases I and II from F. heparinum were N-sulphated disaccharides (∆U-GlcNS,6S/ ∆U,2S-GlcNS and ∆U-GlcNS) and N-acetylated disaccharides (∆U, GlcNAc). This heparinoid had a lower hemorrhagic effect (400μg/ml) when compared to unfractiionated heparins(25μg/ml).The results also suggest a negligible APTT activity of this heparinoid (62.2s). No action was observed on PT indicating that F-3.0M haven t action on the extrinsic pathway. The results showed that the fraction F- 3.0M have inhibitory effect on migration of leukocytes, 64.5% in the concentration of 10 μg/ml (P<0.001). The search for new heparin and/or heparan sulphates analogs devoid of anticoagulant activity is an atractive alternative and may open up a wide variety of new therapeutic applications

Efeito da salinidade da água do mar no rendimento, composição e atividades biológicas de frações polissacarídicas da Chlorophyta Caulerpa cupressoides var. flabellata

Seaweeds sulfated polysaccharides have been described as having various pharmacological activities. However, nothing is known about the influence of salinity on the structure of sulfated polysaccharides from green seaweed and pharmacological activities they perform. Therefore, the main aim of this study was to evaluate the effect of salinity of seawater on yield and composition of polysaccharides-rich fractions from green seaweed Caulerpa cupressoides var. flabellata, collected in two different salinities beaches of the coast of Rio Grande do Norte, and to verify the influence of salinity on their biological activities. We extracted four sulfated polysaccharides-rich fractions from C. cupressoides collected in Camapum beach (denominated CCM F0.3; F0.5; F1.0; F2.0), which the seawater has higher salinity, and Buzios beach (denominated CCB F0.3; F0.5; F1.0; F2.0). Different from that observed for other seaweeds, the proximate composition of C. cupressoides did not change with increased salinity. Moreover, interestingly, the C. cupresoides have high amounts of protein, greater even than other edible seaweeds. There was no significant difference (p>0.05) between the yield of polysaccharide fractions of CCM and its CCB counterparts, which indicates that salinity does not interfere with the yield of polysaccharide fractions. However, there was a significant difference in the sulfate/sugar ratio of F0.3 (p<0.05) and F0.5 (p<0.01) (CCM F0.3 and CCB F0.5 was higher than those determined for their counterparts), while the sulfate/sugar ratio the F1.0 and F2.0 did not change significantly (p>0.05) with salinity. This result suggested that the observed difference in the sulfate/sugar ratio between the fractions from CCM and CCB, is not merely a function of salinity, but probably also is related to the biological function of these biopolymers in seaweed. In addition, the salinity variation between collection sites did not influence algal monosaccharide composition, eletrophoretic mobility or the infrared spectrum of polysaccharides, demonstrating that the salinity does not change the composition of sulfated polysaccharides of C. cupressoides. There were differences in antioxidant and anticoagulant fractions between CCM and CCB. CCB F0.3 (more sulfated) had higher total antioxidant capacity that CCM F0.3, since the chelating ability the CCM F0.5 was more potent than CCB F0.5 (more sulfated). These data indicate that the activities of sulfated polysaccharides from CCM and CCB depend on the spatial patterns of sulfate groups and that it is unlikely to be merely a charge density effect. C. cupressoides polysaccharides also exhibited anticoagulant activity in the intrinsic (aPTT test) and extrinsic pathway (PT test). CCB F1.0 and CCM F1.0 showed different (p<0,001) aPTT activity, although F0.3 and F0.5 showed no difference (p>0,05) between CCM and CCB, corroborating the fact that the sulfate/sugar ratio is not a determining factor for biological activity, but rather for sulfate distribution along the sugar chain. Moreover, F0.3 and F0.5 activity in aPTT test was similar to that of clexane®, anticoagulant drug. In addition, F0.5 showed PT activity. These results suggest that salinity may have created subtle differences in the structure of sulfated polysaccharides, such as the distribution of sulfate groups, which would cause differences in biological activities between the fractions of the CCM and the CCB

Aspectos estruturais, farmacológicos e biológicos de fucanas da alga marrom sargassum vulgare

The present study examines the chemical composition and their effects on free radicals, inflammation, angiogenesis, coagulation, VEGF effects and cellular proliferation of a polysaccharides from alga Sargassum vulgare. The sulfated polysaccharide was extracted from brown seaweed by proteolysis with enzymes maxataze. The presence of proteins and sugars were observed in crude polysaccharides. Fractionation of this crude extract was made with growing concentration of acetone (0.3-1.5 v) and produced four groups of polysaccharides. Anionic polysaccharides from brown seaweed Sargassum vulgare, SV1and PSV1 were fractionated (SV1) and purified (PSV1), and displayed with high total sugars and sulfate content and very low level of protein. This fucan SV1 contains low levels of protein and high carbohydrate and sulfate content. This polysaccharides prolonged activated partial thromboplastin time (aPTT) at 50 μg (>240 s). SV1 was found to have no effect on prothrombin time (PT), corresponding to the extrinsic pathway of coagulation. SV1 exhibits high antithrombotic action in vivo, with a concentration ten times higher than heparin. Polysaccharides from S. vulgare promoted direct inhibition enzymatic activity of thrombin and stimulated enzymatic activity of FXa. SV1 showed optimal inhibitory activity of thrombin (50.2±0.28%) at a concentration of 25 μg/mL. Its antioxidant action on scavenging radicals by DPPH was (22%), indicating the polymer has no cytotoxic action (hemolytic) on ABO and Rh blood types in different erythrocyte groups and displays strong anti-inflammatory action on all concentrations tested in the carrageenan-induced paw edema model, demonstrated by reduced edema and cellular infiltration. Angiogenesis is a dynamic process of proliferation and differentiation. It requires endothelial proliferation, migration, and tube formation. In this context, endothelial cells are a preferred target for several studies and therapies. The antiangiogenic efficacy of polysaccharides was examined in vivo in the chick chorioallantoic membrane (CAM) model by using fertilized eggs. Decreases in the density of the capillaries were assessed and scored. The results showed that SV1 and PSV1 have an inhibitory effect on angiogenesis. These results were also confirmed by inhibition tubulogenesis in rabbit aorta endothelial cell (RAEC) in matrigel. These compounds were assessed in Apoptosis assay (Annexin V - FITC / PI) and cell viability by MTT assay of RAEC. These polysaccharides do not affect the viability and do not have apoptotic or necrotic action. RAEC cell when incubated with SV1 and PSV1showed inhibition of VEGF secretion, observed when compounds were incubated at 25, 50 and 100 μg/μL. The VEGF secretion with the RAEC cell line for 24 h, was more effective for PSV1 at 50 μg/μL(71.4%) than SV1 100 μg/μL (75.9%). SV1 and PSV1 had an antiproliferative action (47%) against tumor cell line HeLa. Our results indicate that these sulfated polysaccharides have antiangiogenic and antitumoral actions

Caracterização estrutural e avaliação das atividades farmacológicas da fucana B extraída da alga Dictyota menstrualis

Seaweeds are a major source of biologically active compounds . In the extracellular matrix of these organisms are sulfated polysaccharides that functions as structural components preventing it against dehydration. The fraction 0.9 (FucB) rich in sulfated fucans obtained from brown seaweed Dictyota menstrualis was chemical characterized and evaluated for pharmacological activity by testing anticoagulant activity, stimulatory action on the synthesis of an antithrombotic heparan sulfate, antioxidant activity and its effects in cell proliferation. The main components were FucB carbohydrates (49.80 ± 0.10 %) and sulfate (42.30 ± 0.015 %), with phenolic compounds ( 3.86 ± 0.016 %) and low protein contamination ( 0.58 ± 0.001 % ) . FucB showed polydisperse profile and analysis of signals in the infrared at 1262, 1074 and 930 cm -1 and 840 assigned to S = O bonds sulfate esters , CO bond presence of 3,6- anhydrogalactose , β -D- galactose non- sulfated sulfate and the axial position of fucose C4 , respectively. FucB exhibited moderate anticoagulant activity , the polysaccharides prolonged time (aPTT ) 200 ug ( > 90s ) partial thromboplastin FucB no effect on prothrombin time (PT), which corresponds to the extrinsic pathway of coagulation was observed. This stimulation promoted fraction of about 3.6 times the synthesis of heparan sulfate (HS) by endothelial cells of the rabbit aorta ( RAEC ) in culture compared with cells not treated with FucB . This has also been shown to compete for the binding site with heparin. The rich fraction sulfated fucans exhibited strong antioxidant activity assays on total antioxidant (109.7 and 89.5 % compared with BHT and ascorbic acid standards ) , reducing power ( 71 % compared to ascorbic acid ) and ferric chelation ( 71 , comparing with 5 % ascorbic acid). The fraction of algae showed cytostatic activity on the RAEC cells revealed that the increase of the synthesis of heparan sulfate is not related to proliferation. FucB showed antiproliferative action on cell lines modified as Hela and Hep G2 by MTT assay . These results suggest that FucB Dictyota menstrualis have anticoagulant , antithrombotic , antioxidant potential as well as a possible antitumor action, promoting the stimulation of the synthesis of antithrombotic HS by endothelial cells and is useful in the prevention of thrombosis, also due to its inhibitory action on species reactive oxygen ( ROS ) in some in vitro systems , being involved in promoting a hypercoagulable state

Síntese e caracterização de ferrita ni-zn pelo método dos precursores poliméricos calcinada por energia de microondas

Magnetic ceramics have been widely investigated, especially with respect to intrinsic and extrinsic characteristics of these materials. Among the magnetic ceramic materials of technological interest, there are the ferrites. On the other hand, the thermal treatment of ceramic materials by microwave energy has offered various advantages such as: optimization of production processes, high heat control, low consumption of time and energy among others. In this work were synthesized powders of Ni-Zn ferrite with compositions Ni1- xZnxFe2O4 (0.25 ≤ x ≤ 0.75 mols) by the polymeric precursor route in two heat treatment conditions, conventional oven and microwave energy at 500, 650, 800 and 950°C and its structural, and morphological imaging. The materials were characterized by thermal analysis (TG/ DSC), X-ray diffraction (XRD), absorption spectroscopy in the infrared (FTIR), scanning electron microscopy (SEM), X-ray spectroscopy and energy dispersive (EDS) and vibrating sample magnetometry (VSM). The results of X-ray diffraction confirmed the formation of ferrite with spinel-type cubic structure. The extrinsic characteristics of the powders obtained by microwave calcination and influence significantly the magnetic behavior of ferrites, showing particles ferrimagnéticas characterized as soft magnetic materials (soft), is of great technological interest. The results obtained led the potential application of microwave energy for calcining powders of Ni-Zn ferrite

Estudo epidemiológico das parasitoses oculares na população de escolares da cidade de Natal-RN, Brasil

The objective of this study is to estimate the prevalence of Ocular Toxocariasis, Diffuse Unilateral Subacute Neuroretinitis (DUSN), Toxoplasma gondii infection and Ocular Toxoplasmosis in a student population in Natal-RN/Brazil and relate it to demographic, epidemiologic and socio-economic risk factors. The incidence of DUSN was observed in patients at the Federal University of Rio Grande do Norte Ophthalmology Service and the Prontoclinica de Olhos Ophthalmology clinic in Natal. In cases where a worm was found in the subretinal space, the result of treatment with photocoagulation using Green Laser (Eye Light ALCON) was evaluated in relation to final visual result. The sample was randomly selected among the schools of the four districts of Natal, according to the type of institution (public or private), its level (elementary or secondary), and study period (morning, afternoon or evening). The school population was studied from March to May, 2001. Initially, the students answered a questionnaire to evaluate demographic, epidemiologic and socio-economic risk factors. Afterwards, the following procedures were carried out: blood samples were taken for Toxoplasmosis (IgG, IgM) serology, hemogram, ophthalmological examination, consisting of clinical history, measurement of visual acuity, refraction under cycloplegia, biomicroscopy of the anterior segment and annexa, funduscopy and examination of extrinsic motility. The prevalence of Toxocariasis was 0.2% or 2 per one thousand students. The sample was insufficient to estimate the prevalence of DUSN. Seventy patients with DUSN diagnosis were examined from January, 2001 to January, 2003. A live worm was found in the subretinal space of all four patients in the acute phase, and these were treated with laser photocoagulation. After follow-up (average = 11.5 months), visual acuity improved in three eyes and remained unaltered in one eye. Worms were found in 22 of the 66 patients in the chronic phase, and these also were treated with laser photocoagulation. After a follow-up period of 13.1 months, on average, visual acuity improved in two of the patients, remained unchanged in 19 and worsened in one. The comparison of visual result before and after treatment was not statistically significant (p = 0.302). The diagnosis of DUSN in the acute phase, followed by prompt localization and destruction of the worm by photocoagulation, can improve the patient s vision. However, destruction of the worm by laser photocoagulation in eyes with DUSN in the chronic phase does not improve visual acuity. Seroprevalence for IgG was 46% (Confidence Interval CI 95%-42.9-49.2%) and for IgM it was 1.4% (CI 95% = 0.8-2.4%). The prevalence of ocular lesion was 1.15% (CI 95% = 0.6 - 2.0%). Socio-economic conditions were determinants in the prevalence of Systemic and Ocular Toxoplasmosis in the bivaried analysis and confirmed in the multivaried analysis (mother s scholarity illiterate/ OR = 2.9 and p < 0.001). The T. gondii infection prevalence, although high, was less than that found in studies performed in the South and Southeast of Brazil and that of Ocular Toxoplasmosis was completely discrepant, varying from 5 to 17 times less. Although important epidemiological variables such as owning a cat, drinking unfiltered water, and coming into contact with rivers or lakes showed an association in the preliminary analysis, they lost their influence when included in the logistic model. Future studies are scheduled to begin in March, 2004, in collaboration with other Brazilian and American universities in an attempt to discover the reason for these findings, as well as identifying the different strains of Toxoplasma gondii, and studying the sources of water utilized by the population of Natal Brazil

Úlcera de pressão em pacientes internados em um hospital universitário em Natal/RN: condições predisponentes e fatores de risco

The pressure ulcers (PU), also known as decubitus ulcers, are defined as injuries caused by the constant pressure exerted on a particular point of the body, causing impairment of blood supply with a decrease or interruption of tissue irrigation, causing occlusion of blood vessels and capillaries, ischemia and cell death. This is a descriptive study with longitudinal design, and panel type, with quantitative approach that aimed to examine the association between predisposing conditions (PC), intrinsic factors (IF) and extrinsic factors (EF) with the occurrence of PU, in hospitalized patients in the Intensive Care Unit (ICU), pain clinical, surgical clinical and neurology wards of a university hospital. The study population was composed of all patients who were restricted to bed during the period from December 2007 to February 2008. The study was approved by the Ethics Committee of HUOL / UFRN (No 135/07). The data-collection took place through a structured formulary of observation, data from medical records and physical examination of patients skins. The results were organized in SPSS 15.0 software, tabulated, categorized and analyzed by descriptive and inferential statistics. Of the 30 patients studied, 43.3% had been hospitalized in the pain clinical and surgical clinic wards, 20.0% in the ICU, 20.0% in the ICU / ward and 16.7% in neurology, being the length of hospitalization in those units of 7 to 18 days (63.3%) and from 19 to 30 days (36.7%), predominantly female and aged ≥ 60 years (60.0%). 19 PU were diagnosed in 43.3% of patients monitored, being 38.5% with one PU between 7 to 18 days and 46.2% with two or more between 19 to 30 days of hospitalization, showing significant relationship (ρ-value = 0029) between length of hospital stay and the number of PU. Was found an association of 35.7% of the PC (cardio-respiratory, hematological, metabolic and psychogenic), IF (age group, oedema, skin changes in humidity and change of body temperature) and EF (type of mattress and strength of body pressure) for all patients studied, statistically significant (ρ-value = 0001), between the average scores in patients with and without PU, with reason chance to 12.0 for the development of PU and there was moderate correlation ( r = 0618) in the presence of this association. Results show the influence of the multiplicity of factors and conditions on the occurrence of PU, which brings us to reflect on the assistance focused on prevention and reduction of these injuries which will encourage the reduction of hospitalization length, physical and psychological suffering, and the possibility of improving the clinical condition of the patient.

Uma perspectiva de extensão do modelo de aceitação de tecnologia para explicar o uso de linguagens de desenvolvimento WEB: pesquisa com desenvolvedores Pyton e Java

The spread of the Web boosted the dissemination of Information Systems (IS) based on the Web. In order to support the implementation of these systems, several technologies came up or evolved with this purpose, namely the programming languages. The Technology Acceptance Model TAM (Davis, 1986) was conceived aiming to evaluate the acceptance/use of information technologies by their users. A lot of studies and many applications have used the TAM, however, in the literature it was not found a mention of the use of such model related to the use of programming languages. This study aims to investigate which factors influence the use of programming languages on the development of Web systems by their developers, applying an extension of the TAM, proposed in this work. To do so, a research was done with Web developers in two Yahoo groups: java-br and python-brasil, where 26 Java questionnaires and 39 Python questionnaires were fully answered. The questionnaire had general questions and questions which measured intrinsic and extrinsic factors of the programming languages, the perceived usefulness, the perceived ease of use, the attitude toward the using and the programming language use. Most of the respondents were men, graduate, between 20 and 30 years old, working in the southeast and south regions. The research was descriptive in the sense of its objectives. Statistical tools, descriptive statistics, main components and linear regression analysis were used for the data analysis. The foremost research results were: Java and Python have machine independence, extensibility, generality and reliability; Java and Python are more used by corporations and international organizations than supported by the government or educational institutions; there are more Java programmers than Python programmers; the perceived usefulness is influenced by the perceived ease of use; the generality and the extensibility are intrinsic factors of programming languages which influence the perceived ease of use; the perceived ease of use influences the attitude toward the using of the programming language

Aprendizado por Reforço com Valores deInfluência em Sistemas Multi-Agente

We propose a new paradigm for collective learning in multi-agent systems (MAS) as a solution to the problem in which several agents acting over the same environment must learn how to perform tasks, simultaneously, based on feedbacks given by each one of the other agents. We introduce the proposed paradigm in the form of a reinforcement learning algorithm, nominating it as reinforcement learning with influence values. While learning by rewards, each agent evaluates the relation between the current state and/or action executed at this state (actual believe) together with the reward obtained after all agents that are interacting perform their actions. The reward is a result of the interference of others. The agent considers the opinions of all its colleagues in order to attempt to change the values of its states and/or actions. The idea is that the system, as a whole, must reach an equilibrium, where all agents get satisfied with the obtained results. This means that the values of the state/actions pairs match the reward obtained by each agent. This dynamical way of setting the values for states and/or actions makes this new reinforcement learning paradigm the first to include, naturally, the fact that the presence of other agents in the environment turns it a dynamical model. As a direct result, we implicitly include the internal state, the actions and the rewards obtained by all the other agents in the internal state of each agent. This makes our proposal the first complete solution to the conceptual problem that rises when applying reinforcement learning in multi-agent systems, which is caused by the difference existent between the environment and agent models. With basis on the proposed model, we create the IVQ-learning algorithm that is exhaustive tested in repetitive games with two, three and four agents and in stochastic games that need cooperation and in games that need collaboration. This algorithm shows to be a good option for obtaining solutions that guarantee convergence to the Nash optimum equilibrium in cooperative problems. Experiments performed clear shows that the proposed paradigm is theoretical and experimentally superior to the traditional approaches. Yet, with the creation of this new paradigm the set of reinforcement learning applications in MAS grows up. That is, besides the possibility of applying the algorithm in traditional learning problems in MAS, as for example coordination of tasks in multi-robot systems, it is possible to apply reinforcement learning in problems that are essentially collaborative

Localização de robôs móveis autônomos utilizando fusão sensorial de odometria e visão monocular

The development and refinement of techniques that make simultaneous localization and mapping (SLAM) for an autonomous mobile robot and the building of local 3-D maps from a sequence of images, is widely studied in scientific circles. This work presents a monocular visual SLAM technique based on extended Kalman filter, which uses features found in a sequence of images using the SURF descriptor (Speeded Up Robust Features) and determines which features can be used as marks by a technique based on delayed initialization from 3-D straight lines. For this, only the coordinates of the features found in the image and the intrinsic and extrinsic camera parameters are avaliable. Its possible to determine the position of the marks only on the availability of information of depth. Tests have shown that during the route, the mobile robot detects the presence of characteristics in the images and through a proposed technique for delayed initialization of marks, adds new marks to the state vector of the extended Kalman filter (EKF), after estimating the depth of features. With the estimated position of the marks, it was possible to estimate the updated position of the robot at each step, obtaining good results that demonstrate the effectiveness of monocular visual SLAM system proposed in this paper

Posicionamento e movimentação de um robô humanóide utilizando imagens de uma câmera móvel externa

This work proposes a method to localize a simple humanoid robot, without embedded sensors, using images taken from an extern camera and image processing techniques. Once the robot is localized relative to the camera, supposing we know the position of the camera relative to the world, we can compute the position of the robot relative to the world. To make the camera move in the work space, we will use another mobile robot with wheels, which has a precise locating system, and will place the camera on it. Once the humanoid is localized in the work space, we can take the necessary actions to move it. Simultaneously, we will move the camera robot, so it will take good images of the humanoid. The mainly contributions of this work are: the idea of using another mobile robot to aid the navigation of a humanoid robot without and advanced embedded electronics; chosing of the intrinsic and extrinsic calibration methods appropriated to the task, especially in the real time part; and the collaborative algorithm of simultaneous navigation of the robots