Ser bacharel e professor: sentidos e relações entre o bacharelado e a docência universitária

The need to research about meanings and relationships between individuals with Bachelor s degrees and Teaching can be considered an exercise capable of aiding in the comprehension of the very performance of the Bachelor as teacher. The guiding question of this study asks: what relationships are established by Bachelors, who are teachers, between their professional education and their performance as a teacher? My objective is to understand the meanings attributed by the Bachelor teachers to teaching at the university level, seeking indicators about the relationships established by them, between their professional education and being a teacher. For this, the methodology used was the Comprehensive Interview, which permits, through the individual s oral discourse, the interpretation of meanings and values expressed by the teachers about their actions. The research is done through oral discourse collected in interviews and from these I analyze the elements that are revealed, and those which help me in the development of this object of study. I understand that the contribution about the possibilities of action and continued education for Bachelors who act as instructors in Higher Education is increasingly necessary, through research, because through continuing education teachers can revisit their actions and reformulate meanings they attribute to teaching as a profession. I consider the debate about meanings about teaching and the relationships with the initial education is not only necessary in the investigation of the Bachelors who act as professors, but also the credentialed teachers, because the teacher s sense of identity and their professional development is constructed through a historical process and in relation to the alternative positioning in the contexts of which they are a part

Diferentes critérios de formulação de rações para frangos de corte no período de 1 a 21 dias de idade

Dois experimentos foram realizados com o objetivo de avaliar diferentes critérios de formulação de rações, baseados em aminoácidos totais e digestíveis, para frangos de corte no período de 1 a 21 dias de idade. As dietas foram formuladas para atender às exigências de metionina, metionina+cistina, lisina e treonina. No primeiro experimento, foram utilizados 800 pintos machos, Hubbard, distribuídos em delineamento inteiramente casualizado com 4 critérios de formulação, para atender às exigências em aminoácidos totais - NRC (1994), Rostagno et al. (1992), Degussa (1997) e AEC (1993), com 4 repetições de 50 aves. No segundo experimento, foram utilizados 600 pintos machos, Cobb, distribuídos em delineamento inteiramente casualizado com 3 critérios de formulação, para atender às exigências em aminoácidos digestíveis - Rostagno et al. (2000), Baker & Han (1994) e Degussa (1997), com 4 repetições de 50 aves. Foram avaliados ganho de peso, consumo de ração e conversão alimentar. Os resultados obtidos demonstraram não haver diferença no desempenho das aves ao serem alimentadas com diferentes critérios de formulação baseados em aminoácidos totais. Ao formular dietas com aminoácidos digestíveis, o padrão estabelecido por Baker & Han (1994) resultaram em melhor desempenho das aves no período avaliado.

Da resistência à ação política, a educação pelo consenso: a ação educativa de Pe. Sabino em Mãe Luiza Natal/RN

This study focuses on a methodology of unchained action by Father Sabino Gentili in Mãe Luiza, suburb of Natal-RN, which has enhanced social participation in what Castells calls project identity. The perception of collective actions, focused on the development of subjects from the perspective of Alain Touraine occurs continuously in a popular neighborhood, whose history marked by conflict mainly related to the resistance in the remaining living space. It is argued that there was an appropriation of resistance identity, which was already present in the community of Mãe Luiza, in order to channel it to create a project identity, through an implicit methodology that has been identified as Pedagogy of Consensus, based on Paulo Freire s concepts of dialogue and participation. Therefore, by means of qualitative research, using tools such as semi-structured interviews and documented sources, we tried to describe the intent of the action of a social actor and the political and educational strategies that motivate the collective action aiming a social change, observing the elements present in this action that allowed the continuity of organizational and participating processes through the dynamics of Mãe Luiza s neighborhood

Reconceitualização das categorias de skemp de compreensão relacional e compreensão instrumental como critérios globais

The thesis presents a systematic description about the meaning, as Skemp, relational understanding and understanding instrumental, in the context of mathematics learning, being that we had as a guide his understanding of the schema. Especially, we analyze some academic productions, in the area of Mathematics Education, who used the categories of understanding relational and instrumental understanding how evaluative instrument and we see that in most cases the analysis is punctual. Being so, whereas the inherent understanding relational schema has a network of connected ideas and non-insulated, we investigated if the global analysis, where it is the understanding of the diversity of contributory concepts for formation of the concept to be learned, is more appropriate than the punctual, where does the understanding of concepts so isolated. For this, we apply a teaching module, having as main content the Quaternos Pythagoreans using History of Mathematics and the work of Bahier (1916). With the data we obtained the teaching module to use the global analysis and the punctual analysis, using research methodology the Case Study, and consequently we conduct our inferences about the levels of understanding of the subject which has made it possible for us to investigate the ownership of global analysis at the expense of punctual analysis. On the opportunity, we prove the thesis that we espouse in the course of the study and, in addition, we highlight as a contribution of our research evidence of need for a teaching of mathematics that entices the relational understanding and that evaluation should be global, being necessary to consider the notion of schema and therefore know the schematic diagram of the concept that will be evaluated

Ingressar na ufrn: trajetórias escolares e universitárias de estudantes egressos da educação básica da rede pública

On the beginnings of the XXI century the brazilian universities was claimed by the Government and by the society to rebuild your ways of selecting students. Many questions are behind this theme, that goes since the concernings of the higher education institutions about select and graduate students, and now also students from disadvantaged sectors of the society; but also about personal issues, like concerns of the everyday of millions of youngs that integrates the brazilian society and that need to decide about your professional future after the finish of the Basic Education. The present thesis has as objective analyse the processes of the transition between the Basic Education and Higher Education on the point of view of students that achieved a place on the public university. This study was accomplished on the Federal University of Rio Grande do Norte [UFRN on the original language], that implemented an Access and Social Inclusion Policy (PAIS [on the original language]) on the year of 2003, and since than a series of social actions had been developed. Among the main, we highlight the Inclusion Score action, an adicional score [on the entrance selection exam] for graduated students from public schools, which considers social and economic criteria and the academic development of these candidates on your Basic Education. Through quizzes and interviews with the graduated university students from public network, we could know the social, economic and academic profile of the students that entered on the UFRN by the time of the development of your PAIS, your schools and university trajectories, revealing some of the dilemmas, strategies, difficulties and personal cost of those that try to remain on the educational system besides the adversity conditions of schooling. For the theory foundation, we use authors like Bourdieu (1992, 1996, 2003); Coulon (1993, 2008); Ramalho (2004, 2007, 2008, 2010); Ramalho, et al (2011); Charlot (2001, 2003, 2005); Zago (2011); Nogueira, Romanelli e Zago (2011), among others, that contributed for a better analysis and understanding of thought and actions of the students in your own formative trajectories. Although we know that the educational inequalities are many, we found that the UFRN policy brought and is bringing many significant results, on the perspective of contribute with the increase of access for graduated students from the public network, and with the inclusion of these on the university

Em busca de novas territorialidades pedagógicas para a identidade da Educação Física no Ensino Médio integrado: uma perspectiva pós-crítica

Cet étude s agit du domaine de l Éducation Physique comme composante curriculaire dans le contexte de l Ensino médio integrado (l enseignement secondaire professionnel intégré) dans le IFRN, Campus Natal Zona Norte (Régio Nord). Son objectif principal est sur le plan éducatif des actions de l enseingant au procès des convivialités avec la culture corporale à partir des expériences, désires, besoins et volontés des apprenants dans la perspective de l imersion dans le monde de la créativité, de la recherche, de la connaissance et de la transformation de l identité pédagogique de la composante curriculaire. Dans ce sens, l étude a eu comme objectif l élaboration d une propisition pédagogique, fondamentée sur la Théorie Post-critique de l éducation qui contribue pour la configuration de l identité de l Éducation Physique dans les cours téchniques intégrés de niveau secondaire. La recherche s est configuré dans une intervention pédagogique fondamenté sur les préssuppositions methodologique d une expérience empirique du genre recherche-action apliqué dans l univers scolaire des cours thécniques intégrés de l enseignement secondaire de l IFRN, Campus Natal Zona Norte. Les sujets qui ont participé de la recherche, sont les apprenants des groupes de la première année du cours de Commerce et Éléctronique de la soirée (13h à 18h), inscrit à partir de l année 2012. Les instruments utilisés pour la recherche ont été deux questionaires et une cahier de bord. Les résultats obtenus sont disposés dans des graphiques qui représentent les paroles des sujets après le procès d intervantion et les analyses réalisées sous l étude-recherche, qui ont été faites por l analyse de contenu, de l image principale de la population recherchée. On considère que les résultats de la recherche ont été plausibles à la mesure que au-delà du support et de la participation dans la recherche, les réponses obtenues ont démontré que le procès d intervantion pédagogique a été pertinent pour les apprenants des cours téchniques intégrés de niveau secondaire de Commerce et Électronique de l IFRN, Campus Natal Zona Norte. Le sense essentielle de cette thèse s est concentrée dans la dimension interculturelle pour l Éducation Physique dans le secondaire intégré, comme un travail fondamenté à partir des temoignage des apprenants et par la conception post-critique du curriculum qui refuse les explications évidentes et instituées comme des véritées finales dans l objectif de réguler et controler les sujets de l éducation. L option faite par cet abordage de thèse a été pour rompre avec l établi à partir de la proposition d un dialògue, avec les apprenants, à la recherche de nouveaux territoires pédagogiques pour l Education Physique à l enseignement intégré de l IFRN, Campus Natal Zona Norte. Des territoires qui occupent des espaces dans la culture scolaire, dans une dynamique dialogique avec les apprenants, qui se défine politique et pédagogiquement pour la diversité culturelle du mouvement, qui aborde le concept de mouvement dans la proximité des actions corporales cotidiennes et qui propose de nouvelles possibilités et de recréations pour les pratiques de la culture corporale. La perspective post-critique ouvre des possibilités pour de nouvelles langages en fortifiant les narratives de ce qui ont toujours entendu et cependant ont silencié ses voix et ainsi, la thèse a confirmé que, l étude présent et la recherche supporté par la théorie post-critique du curriculum ont possibilité une nouvelles configuration pour l identité pédagogique de l Éducation Physique dans la condition de composant curriculaire des cours téchniques intégrés de niveau secondaire de l IFRN au Campus Natal Zona Norte

Contar no caminho: escritas de si, percursos de formação e inserção institucional de professores da infância

El trabajo tiene como objeto de estudio la percepción de profesores de la infancia respecto sus itinerarios de formación y proyectos de inserción institucional, y como objetivo analizar como los participantes de la investigación articulan, narrativamente, sus itinerarios de formación y proyectos de actuación profesional para inserción institucional en un Colegio de Aplicación. Adopta principios epistemológicos y métodos de la investigación (auto)biográfica: Ferrarotti 2010); Delory-Momberger (2008, 2011, 2012); Josso (2010); Nóvoa (2007); Nóvoa y Finger (2010); Dosse (2009); Passeggi (2011, 2012, 2013); Souza (2004, 2010, 2013). El corpus está constituido por diez memoriales académicos; diez proyectos de actuación profesional; la transcripción de entrevistas realizadas en dos grupos de discusión y el diario de campo de la investigadora. Las analises se basan en las contribuciones de Jovchelovitch y Bauer (2010), Schütze (2010) y Weller (2006). Los resultados de la investigación permitiran concluir que el proceso de biografización y el proyecto de actuación profesional introduce una doble función: constituirse en una herramienta de evaluación y como dispositivo de formación, permitiendo a los profesores la reflexión sobre las particularidades del proceso de biografización en el contexto de injunción institucional y el conocimiento de las potencialidades de sus percursos de formación. Permitiran, todavia, la definición de tres eixos organizadores de una cartografía de formación, tomando lo que Nóvoa (2007) sugiere sobre los procesos de Adesión, Acción y Autoconsciencia en la constitución de la identidad docente. Ao relatar sus percursos de formación los profesores reconstituyen adesiones a los principios, valores y proyectos en diferentes contextos de formación, revisitan acciones desarrolladas en el ejercicio de la profesión y elaboran reflexiones que resultan en la autoconciencia de potencialidades y limitaciones de sus acciones en la institución. El trabajo contribuye para pensar la producción de memoriales y proyectos académicos de experiencia profesional como espacio fundador de reflexión sobre la formación del profesorado de la infancia

O currículo e as práticas pedagógicas na EJA: concepções e crenças dos professores da escola municipal Francisca Leonísia Cruz

The present investigation deals with the Curriculum and Pedagogical Practices of Young and Adults, EJA, and articulates with the conceptions and beliefs of teachers sitting. The empirical scope of this investigation consisted in the Municipal School Francisca Leonísia, located in the Agrarian Reform Settlement Serra Nova, city of Florânia/RN. Seeks to analyze the relationship between the Curriculum and Educational Practices of Young and Adult EJA - conceptions beliefs of these teachers. This work is based on qualitative research, interpretative character reflective and makes use of documentary analysis, structured interviews and reflective sessions as methodological procedures which ensure the achievement of our goals in research. These procedures allowed us to enter the practice setting and curriculum for teachers to understand how they think, prepare and practice of adult education in school curriculum research field. The documentary analysis provided the rethinking of the curriculum selected references, Political Pedagogical Project and Proposed Course of EJA, from a critical reading of concepts and conceptions given in these references, with a view to construction and reconstruction of concepts that reclaim the identity of young people and adult field, inserted in the Rural Workers Movement landless/MST. As reflective sessions were constituted in spaces of collective training and allowed the group to selfreflection e collective reflection about the ideas and beliefs that permeate the curriculum and guide their practices education in adult education. In these areas of training are also discussed current problems of adult education, the construction of an educational project of the adult education field to, warranties of learning and cultural identity of the adult education field and placed in the context of the MST. Under this view, it is concluded that the conceptions and beliefs of teachers seated directly relate to the curriculum designed, developed and practiced in adult education, as well as the educational practices that permeate the curriculum. This relation is in the midst of adversities of Rural Education, inserted in the Movement of Landless Rural Workers-MST, and requires the commitment of teachers to the necessary changes to an education are critical and emancipatory

Acompanhamento do memorial de formação: entre formar e formar-se

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

O processo de cuidar em Unidade de Terapia Intensiva

The environment of Intensive Care Unit (ICU) is commonly referred to as a place where caring is inextricably linked to high technology. The care in ICU often changes the patient into a taxpayer being left apart from its complexity and sometimes seen through a reductionist perspective. Thus, studies circa the care process are needed oriented from a historical ransom, raising the prospect of a more centralized human care. Hence, this study aimed to analyze the care process in a nursing intensive care unit from the perspective of the professional, family and patients. The study is characterized from a qualitative, descriptive and exploratory methodological approach. The actors were participating nursing professionals, patients and family members of an intensive care unit of Mossoró / RN. Data were collected in the period of May-June 2011, through interviews and observation of activities performed by nursing professionals, and their records in the chart. Data analysis was divided into topics and subtopics representing the phases and shapes that formed the collection. The analysis and discussion of the interviews were based on Bardin's proposal, when we created categories from a process of sorting and grouping criteria adequately defined. The observation of nursing records intended to observe the emphasis which is described in those notes as well as their consistency with practice of FCN and resolution 358/2009. The analysis showed that the nursing staff also performs work focused on mechanized activities and technical-bureaucratic institution that seem to override the needs of patients. In an overview, the care provided by professionals occurs either fragmented or insipient, however there is a service that involves other aspects beyond technical-curative practice, considering that major attention is given to the family and patient, focused on the concern of Nursing guiding their actions in not only the performance of procedures. However, the process of humanizing not always ends with an engagement between professional and patient, which mischaracterizes the true meaning of human care. The records also showed a tendency to focus on caring in a positivist line, where, in most cases, the factors of the disease and the obligation to meet the productivity have overshadowed other relevant aspects to a holistic understanding of caring. Regarding FCN Resolution No. 358/2009, which guides a systematization of nursing care, it is confirmed a technical view, a fragmented and superficial view of the patient, as well as a weakness of care, caused by ignorance and unpreparedness of the entire team. The perspective of caring demonstrates a reality with dialectic between what is proposed in a humane nursing and what happens in this performance space. Besides, it was shown a daily full of important considerations that arise in professional practice, in their views and also those people who were participants in the process

Diagnósticos de enfermagem em pacientes no pós-operatório imediato de prostatectomia de um Hospital Universitário de Natal-RN

The characterization of the nursing diagnoses in prostatectomized patients is important to provide an unique nursing language, facilitating the communication between professionals and patients. The objective of this study was to analyze the nursing diagnoses of patients in the immediate prostatectomy postoperative period. This is a cross-sectional and descriptive study, developed at the surgical-clinic of Onofre Lopes University Hospital, in the Natal City RN - Brazil. The sample was composed of 50 patients included by the criteria: have presented a diagnosis of a benign prostatic hyperplasia or a prostate cancer, have been subjected to a prostate surgery at the mentioned hospital, and have been in the immediate postoperative period at the moment of the data collection. The exclusion criteria were: haven t been in an appropriate physical and mental condition, have presented a brain vascular disease, a lung disease, an advanced liver disease, a heart disease or a extensive coronary artery disease. The data collection instruments were: the script of an interview and physical examination. The data collection period was between November 2010 and April 2011. The data were organized in two phases: the diagnostic process and the construction of the database. The project was approved by the Ethics Committee of the Federal University of Rio Grande do Norte The results showed that most patients came from the countryside, was living with partners, had an average of 67.78 years, was pensionerthose with low schooling, Catholic and often did not perform preventive examinations of prostatic disease. The patients showed an average of 9.48 nursing diagnoses, defining characteristics 21.70 and 20.72 related or risk factors per patient. We identified 30 nursing diagnoses, of which 7 were above the 75 percentile: Risk of falls, Impaired ambulation, Risk of infection, Self-care deficit bath / hygiene and dress up and Risk for deficient fluid volume. The top six nursing diagnoses were in all patients, and therefore could not apply any statistical test. The others ND were associated with their defining characteristics and related or risk factors. We conclude that the nursing diagnoses identified in this study contribute to the progress of the nursing care to the prostatectomized patients in post-surgery period, allowing the deployment of nursing actions for the effective resolution of identified problems

Validação de conteúdo do instrumento para consulta de enfermagem na visita domiciliar às pessoas com lesão medular: um enfoque no autocuidado

This study aimed to validate the contents of an Instrument for Nursing Consultation in the Home Visit of people with Spinal Cord Injury (INCEVDOP-LM), based on the Self-Care Deficit Theory. The methodological development study was conducted with spinal cord injured (SCI) people ascribed in the Family Health Units the city of Natal/RN/Brazil, and with the nurses of these institutions. The study was conducted from Januray 2012 to January 2013 in two phases: the first aimed to identify the need for self-care of persons with SCI, and the second to develop and validate the INCEVDOP-LM. The first phase consisted of a census study of people with SCI living in Natal/RN. In the second phase, a non-probabilistic convencience sample of subjects was selected to form two groups: First stage - Group 1 of the first stage was comprised by 73 adults with SCI diagnosed with paraplegia or tetraplegia, with cognitive function preserved and that were registered to some family health unit; Group 2 of the Second phase was composed of six experts that were nurses with doctoral formation, scientific experience in the area of technology development or assistance to persons with SCI, and with publications in periodicals Qualis A2. Data collection of the first phase was conducted through home visits of people with SCI that responded three instruments: Questionnaire I (comprised of demographic and socioeconomic variables), The Competency Rating Scale for Self-care (ASA) and the Barthel Index (an instrument for evaluation of functional capacity). The research for the second phase was conducted in two stages: I-construction of the INCEVDOP LM; II-validation of the INCEVDOP-LM. The instrument and an evaluation form were forwarded to the experts for the validation. The correlations between the responses were analyzed by the Kappa test, with accepting values of>0.75. The evaluation criteria were: organization, clarity, simplicity, readability, appropriateness of vocabulary, objectivity, accuracy, reliability and suitability and the positive responses with frequency values of≥90% were considered excellent. The chi-square test was used to investigate the differences between proportions. The study attended to the principles of Human Rights CNS Resolution 196/96. Results were reported by means of four articles derived from the study. The findings indicate that the items that showed disagreement among experts (k=0.02) were diagnoses, interventions and evaluation of the nursing features pertaining to the domains of Nutrition, Hygiene, Elimination, Physical, Social and Psychological, and of the Ability to perform work activities feature. Agreement among the experts were reported for the other items, with kappa ranging from 0.72 to 1. After removing items with disagreement, all criteria achieved excellent rates and no significant differences were observed between the proportions of responses of evaluation of experts (p>0.05). We conclude that the instrument shows validity to serve as a guide for nurses to conduct a systematic consultation during the home visit to people with spinal cord injury, with emphasis on self-care. The instrument must go through other levels of validation when applied in the clinical setting

Modelos para análise e dimensionamento de painéis de alvenaria estrutural

The main objective of this thesis was the study of bracing panels of structural masonry, by applying the Finite Element Method and Strut and Tie Method. It was analyzed the following aspects: the effect of orthotropy on the behavior of the panels; distribution of horizontal forces between panels for buildings; comparison between Equivalent Frame and Finite Elements models; panels design with the Strut and Tie Method. The results showed that one should not disregard the orthotropy, otherwise this can lead to models stiffer than the real. Regarding the distribution of horizontal forces, showed that the disregard of lintels and shear deformation leads to significant differences in the simplified model. The results showed also that the models in Finite Element and Equivalent Frame exhibit similar behavior in respect to stiffness of panels and stress distribution over the sessions requested. It was discussing criteria for designing Strut and Tie Method models in one floor panels. Then, the theoretical strength these panels was compared with the rupture strength of panels tested in the literature. The theoretical maximum strength were always less than the rupture strength of the panels obtained in tests, due to the fact that the proposed model cannot represent the behavior of the masonry after the start of the panel cracking due to plasticization of the reinforcement

Argamassas do grupo escolar Augusto Severo/RN: caracterização e incidência de manifestações patológicas

The search for cultural heritage preservation should be a constant, in order to minimize the lost of historical and cultural identity of a country. As part of this cultural heritage, highlights the importance of historical buildings. For the principles of restoration are met its important to know the state of conservation and the existing materials. Given the above, this work aims to study the pathological manifestations of the mortar coating from the Grupo Escolar Augusto Severo. For this, was conducted historical survey of the building, on-site visits with visual observation, collecting samples of mortar coating and characterization through visual and laboratory analysis, XRF, XRD, TG/DTG, OM and SEM-EDS. From the observations, pathological manifestations were found as: cracks, detachment of the coating, dirt, use of inappropriate material basis of cement, efflorescence, mold and mildew and also incompatible material base of cement. It was found that the pathological manifestations were intensified due to lack of coverage in some spots and especially the abandonment of the building, that many years does not have restoration or any other type of preventive and corrective maintenance. The results of laboratory tests indicated that the mortars studied are based on lime, with calcitic nature, and siliceous aggregate, with the presence of clay in two samples. From the samples collected, two are composed of lime, sand and clay and two by lime and sand. In this regard, it is important to conduct periodic inspections and maintenance, as well as carrying out restoration with use of material compatible with the original

Avaliação da Usabilidade de Interfaces Web segundo Critérios Ergonômicos de Bastien e Scapin: Pesquisa com os Ambientes Virtuais de Educação à Distância Aulanet, E-Proinfo e Teleduc

Este trabalho tem dois objetivos: avaliar a usabilidade de três interfaces de ambientes virtuais de educação à distância através de duas técnicas avaliativas e identificar os fatores influenciadores da percepção de usabilidade dos ambientes avaliados. Os sistemas de educação à distância escolhidos foram o AulaNet, o E-Proinfo e o Teleduc, por serem desenvolvidos no Brasil e terem distribuição gratuita. A avaliação da usabilidade foi realizada através de duas técnicas documentadas na literatura. A primeira técnica de avaliação, do tipo preditiva ou diagnóstica, foi realizada pelo autor e um concluinte do curso de Sistemas de Informação do Centro Federal de Educação Tecnológica do estado do Piauí (CEFET-PI), mediante a observação de um checklist denominado Ergolist. A segunda avaliação, do tipo prospectivo, foi efetivada com o usuário sendo o próprio avaliador das interfaces, através de um questionário. A amostra foi composta de 15 professores e 15 alunos do CEFET-PI. Os resultados colhidos foram analisados a partir da estatística descritiva e testes de chi-quadrado. Os resultados mostraram que os ambientes apresentarem problemas de adaptabilidade, pois não possuem flexibilidade e nem levam em consideração a experiência do usuário. Na análise inferencial, foi constatado que o tempo de uso da Internet não afetou significativamente sua avaliação da usabilidade dos três ambientes, assim como na maior parte das variáveis de usabilidade não foram influenciadas pelo tipo de usuário , sexo e escolaridade . Por outro lado, em vários dos critérios ergonômicos avaliados, as variáveis de sistema tipo de ambiente e experiência com computador e a variável demográfica faixa etária afetaram a percepção de usabilidade dos ambientes virtuais de educação à distância