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The problem of this study was to test and compare the impact of two alternative educational treatments on the rate of success among high-risk students enrolled in the United States History telecourse at Richland College, DCCCD during the Spring Semester of 1980. The purposes of the study were to determine whether 1. The rate of success, that is, the proportion of students completing the course with a grade of "C" or higher, would increase among high-risk students in either experimental group; 2. The rate of success would increase among high-risk students with poor reading skills in either experimental group; 3. The rate of success would increase among high-risk students with poor academic motivation for telecourses in either experimental group; 4. The rate of success would increase among high-risk students when related to the demographic variables used as predictors and collected for the students who were in either experimental group; 5. There would be a difference in the effects of experimental treatment I and experimental treatment II in helping students with poor reading skills to complete the course with a grade of "C" or higher; 6. There would be a difference in the effects of experimental treatment I and experimental treatment II in aiding students with different levels and types of motivation to complete the course with a grade of "C" or higher; 7. There would be a difference in the effects of experimental treatment I and experimental treatment II in helping students with the various demographic characteristics used in the prediction equation to complete the course with a grade of "C" or higher.

In this dissertation, new approaches that utilize the one-way cryptographic hash functions in designing improved network security protocols are investigated. The proposed approaches are designed to be scalable and easy to implement in modern technology. The first contribution explores session cookies with emphasis on the threat of session hijacking attacks resulting from session cookie theft or sniffing. In the proposed scheme, these cookies are replaced by easily computed authentication credentials using Lamport's well-known one-time passwords. The basic idea in this scheme revolves around utilizing sparse caching units, where authentication credentials pertaining to cookies are stored and fetched once needed, thereby, mitigating computational overhead generally associated with one-way hash constructions. The second and third proposed schemes rely on dividing the one-way hash construction into a hierarchical two-tier construction. Each tier component is responsible for some aspect of authentication generated by using two different hash functions. By utilizing different cryptographic hash functions arranged in two tiers, the hierarchical two-tier protocol (our second contribution) gives significant performance improvement over previously proposed solutions for securing Internet cookies. Through indexing authentication credentials by their position within the hash chain in a multi-dimensional chain, the third contribution achieves improved performance. In the fourth proposed scheme, an attempt is made to apply the one-way hash construction to achieve user and broadcast authentication in wireless sensor networks. Due to known energy and memory constraints, the one-way hash scheme is modified to mitigate computational overhead so it can be easily applied in this particular setting. The fifth scheme tries to reap the benefits of the sparse cache-supported scheme and the hierarchical scheme. The resulting hybrid approach achieves efficient performance at the lowest cost of caching possible. In the sixth proposal, an authentication scheme tailored for the multi-server single sign-on (SSO) environment is presented. The scheme utilizes the one-way hash construction in a Merkle Hash Tree and a hash calendar to avoid impersonation and session hijacking attacks. The scheme also explores the optimal configuration of the one-way hash chain in this particular environment. All the proposed protocols are validated by extensive experimental analyses. These analyses are obtained by running simulations depicting the many scenarios envisioned. Additionally, these simulations are supported by relevant analytical models derived by mathematical formulas taking into consideration the environment under investigation.

[EN] Interaction is defined as the realization of a reciprocal action between two or more people or things. Particularly in computer science, the term interaction refers to the discipline that studies the exchange of information between people and computers, and is generally known by the term Human-Computer Interaction (HCI). Good design decisions and an adequate development of the software is required for efficient HCI to facilitate the acceptability of computer-based applications by the users. In clinical settings it is essential to eliminate any barrier and facilitate the interaction between patients and the system. A smooth communication between the user and the computer-based application is fundamental to maximise the advantages and functionalities offered by the system. The design of these applications must consider the personal and current needs of the user by applying a User-Centered Design methodology. The main purpose of this research work is to contribute in the improvement of HCI-based applications addressed to the clinical context, particularly to enhance computer-based interactive sessions to support people suffering from a mental disorder such as Major Depression (MD). Thanks to the advances in Artificial Intelligence techniques, it is now possible to partially automate complex tasks such as the continuous provision of Cognitive-Behavioural Therapies (CBTs) to patients. These CBTs require good levels of adaptability and variability during the interaction with the patient that facilitates the acceptability in the user, an optimal usability and good level of engagement for a successful mid/long term use of the application and treatment adherence. The modelling of complex deliberative and affective processes in artificial systems can be applied to support the prevention and treatment of mental health related issues, enhancing the continuous and remote assistance of patients, saving some economical and clinical resources and reducing the waiting lists in the health services. In this regard, the efforts of this Thesis have been concentrated on the research of two main lines: (1) the generation and planning of adequate contents in an interactive system to support the prevention and treatment of MD based on characteristics of the user; and (2) the modelling of relevant affective processes able to communicate the contents in an emotional effective way taking into account the importance of the affective conditions associated with the MD in the users. Rule Based Systems and the appraisal theory of emotions have been the roots used to develop the main two modules of the computational Framework presented: the Contents Management and the Emotional Modules. Finally, the obtained Framework was integrated into two interactive systems to evaluate the achievement of the research objectives. The first system has been developed in the context of the Help4Mood European research project and its main aim was to support the remote treatment of patients with MD. The second scenario was a system developed to prevent MD and suicidal thoughts in the University community, which was developed in the context of the local PrevenDep research project. These evaluations have indicated that the proposed Framework has reached good levels of usability and acceptability in the target users thanks to the personalizations and adaptation capabilities of the contents and in the way how these contents are communicated to the user. The research work and the obtained results in this Thesis has contributed to the state of the art in HCI-based systems used as support in therapeutic interventions for the prevention and treatment of MD. This was obtained by the combination of a personalized content management to the patient, and the management of the affective processes associated to these pathologies. The developed work also identifies some research lines that need to be addressed in future works to get better HCI systems used for therapeutic purposes. / [ES] Interactuar se define como la realización de una acción recíproca entre dos o más personas o cosas. Particularmente en informática, el término interacción se refiere a la disciplina que estudia el intercambio de información entre las personas y computadoras, y suele conocerse por el término anglosajón Human-Computer Interaction (HCI). Un buen diseño y un adecuado desarrollo del software es necesario para lograr una HCI eficiente que facilite la aceptabilidad del sistema por el usuario. En entornos clínicos es fundamental eliminar cualquier tipo de barrera y facilitar la interacción entre los pacientes y el computador. Es de vital importancia que haya una buena comunicación entre usuario y computador, por este motivo el sistema debe de estar diseñado pensando en las necesidades actuales, cambiantes y personales del usuario, basándose en la metodología de diseño centrado en el usuario. El propósito principal de esta investigación es la identificación de mejoras en HCI aplicada en entornos clínicos, en concreto para dar soporte a personas con trastornos mentales como la Depresión Mayor (DM) y que precisan de terapias psicológicas adecuadas y continuas. Gracias a técnicas de Inteligencia Artificial, es posible automatizar eficientemente ciertas acciones asociadas a los procesos de las terapias cognitivo-conductuales (CBTs, del inglés Cognitive-Behavioural Therapies). Los sistemas de ayuda a la CBT, requieren de una adaptabilidad y variabilidad en la interacción para favorecer la usabilidad del sistema y asegurar la continuidad de la motivación del paciente. Una buena gestión de esta automatización influiría en la aceptabilidad de los pacientes y podría mejorar su adherencia a los tratamientos y por consiguiente mejorar su estado de salud. Adicionalmente, la unión de procesos deliberativos dinámicos pueden liberar recursos clínicos, mejorando el control de los pacientes, y reduciendo los tiempos de espera y los costes económicos. En este sentido, los esfuerzos de esta Tesis se han centrado en la investigación de dos líneas diferentes: (1) la selección y planificación adecuada de los contenidos presentados durante la interacción a través de una planificación dinámica y personalizada, y (2) la adecuación de la comunicación de los contenidos hacia el paciente tomando en cuenta la importancia de los procesos afectivos asociados a estas patologías. Los Sistemas Basados en Reglas (SBR) han sido la herramienta utilizada para dar soporte a los dos módulos principales que componen el Framework presentado en esta Tesis: el módulo de gestión de los contenidos y el módulo emocional. Concluida la fase de diseño, desarrollo y testeo, el Framework fue adaptado e integrado en sistemas reales, para validar la viabilidad y la adecuación del marco de trabajo de esta Tesis. En primer lugar, el sistema se aplicó durante tres años en el tratamiento de la DM en varios centros clínicos europeos en el contexto del Proyecto Europeo de investigación Help4Mood. Finalmente, el sistema fue evaluado en la tarea de prevención de la DM y del suicidio en el Proyecto Local de investigación PrevenDep, de un año de duración. El feedback de estas evaluaciones demostraron que el HCI del Framework tiene unos niveles altos de usabilidad y aceptación, gracias a la personalización, variabilidad y adaptación de los contenidos y de la comunicación de los mismos. Los experimentos computacionales llevados a cabo en esta Tesis han permitido avanzar el estado del arte de sistemas computacionales emocionales aplicados en entornos terapéuticos para la prevención y tratamiento de la DM. Principalmente, gracias a la combinación de una gestión personalizada de los contenidos hacia el paciente tomando en cuenta la importancia de los procesos afectivos asociados a estas patologías. Este trabajo abre nuevas líneas de investigación, como la aplicación de este sistema en otras patologías de salud mental en las qu / [CA] Interactuar es defineix com la realització d'una acció recíproca entre dos o més persones o coses. Particularment en informàtica, el terme interacció es refereix a la disciplina que estudia l'intercanvi d'informació entre les persones i computadores, i es sol conèixer pel terme anglosaxó Human-Computer Interaction (HCI). Un bon disseny i un adequat desenvolupament del software és necessari per aconseguir una HCI eficient que faciliti l'acceptabilitat del sistema per l'usuari. En entorns clínics és fonamental eliminar qualsevol tipus de barrera i facilitar la interacció entre els pacients i el computador. És de vital importància que hi hagi una bona comunicació entre l'usuari (o pacient) i el computador, per aquest motiu el sistema ha d'estar dissenyat pensant en les necessitats actuals, cambiants i personals de l'usuari, basant-se en la metodologia de disseny centrat en l'usuari. El propòsit principal d'aquesta investigació és la identificació de millores en HCI aplicada en entorns clínics, en concret per donar suport a persones amb trastorns mentals com la Depressió Major (DM) i que precisen de teràpies psicològiques adequades i contínues. Gràcies a tècniques d'Intel·ligència Artificial, és possible automatitzar eficientment certes accions asociades al processos de les teràpies cognitiu-conductuals. Els sistemes computacionals de ajuda a la CBT, requereixen d'una adaptabilitat i variabilitat en la interacció per afavorir la usabilitat del sistema i assegurar la continuïtat de la motiviació del pacient. Una bona gestió d'aquesta automatització influiria en l'acceptabilitat dels pacients i podria millorar la seva adherència als tractaments i per tant millorar el seu estat de salut. Addicionalment, la unió de processos deliberatius dinàmics poden alliberar recursos clínics, millorant el control dels pacients, i reduint els temps d'espera i els costos econòmics. En aquest sentit, els esforços d'aquesta Tesi s'han centrat en la investigació de dues línies diferents: (1) la selecció i planificació adequada dels continguts presentats durant la interacció a través d'una planificació dinàmica i personalitzada, i (2) l'adequació de la comunicació dels continguts cap al pacient tenint en compte la importància dels processos afectius associats a aquestes patologies. Els Sistemes Basats en Regles (SBR) han estat la eina utilitzada per donar suport als dos mòduls principals que componen el Framework presentat en aquesta Tesi: el mòdul de gestió dels continguts oferits a l'usuari; i el mòdul emocional. Conclosa la fase de disseny, desenvolupament i testeig, el Framework va ser adaptat als dominis corresponents i integrat en sistemes madurs per ser avaluat en dos escenaris reals, per validar la viabilitat i l'adequació del Framework d'aquesta tesi. Primerament, el sistema es va aplicar durant tres anys en el tractament de la DM major en diversos centres clínics europeus en el context del Projecte Europeu d'investigació Help4Mood. Finalment, el sistema va ser avaluat en la tasca de prevenció de la DM i del suïcidi al Projecte Local d'investigació PrevenDep, d'un any de durada. El feedback de les avaluacions han demostrat que el HCI del Framework obté uns nivells alts d'usabilitat i acceptació, gràcies a la personalització, variabilitat i adaptació dels continguts i de la comunicació. Els experiments computacionals duts a terme en aquesta Tesi han permès avançar l'estat de l'art de sistemes computacionals emocionals aplicats en entorns terapèutics per a la prevenció i tractament de la DM. Principalment, gracies a la combinació d'una gestió personalitzada dels continguts cap al pacient tenint en compte la importància dels processos afectius associats a aquestes patologies. Aquest treball obre noves línies d'investigació, com l'aplicació d'aquest sistema en altres patologies de salut mental en què sigui recomanable l'aplicació de sessions terapèutiques. / Bresó Guardado, A. (2016). A Computational Framework for Planning Therapeutical Sessions aimed to Support the Prevention and Treatment of Mental Health Disorders using Emotional Virtual Agents [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/64082

Vår intention med arbetet är att upptäcka olika metoder för att främja arbetet med högläsning. Syftet med litteraturöversikten är därför att granska tidigare forskning som redogör för olika metoder om högläsning för att gynna elevernas läsförmåga. Detta syftet leder till forskningsfrågan som litteraturöversikten utgår ifrån: Vilka metoder för högläsning gynnar utvecklingen av elevers läsförmåga? Datainsamlingen består av systematiska sökningar genom söksträngar i olika databaser som bland annat ERIC (EBSCO), Swepub, Scopus och DiVA. Forskningen är både internationell och nationell. Tematisk analys används för att analysera datainsamlingen. Utifrån analysen identifieras teman som utgör våra rubriker i resultatdelen. Studiens resultat visar att interaktiv högläsning är en metod som gynnar elevers literacyutveckling. Även andra faktorer såsom valet av bok och vid vilken tidpunkt på dagen påverkar främjandet av läsutvecklingen. Slutsatsen av litteraturstudien är att interaktiv högläsning, val av bok och tidpunkt med flera, främjar läskunnigheten och förståelsen. Ett aktivt lärande bidrar till en ökad motivation hos eleverna. / Our intention with this study is to discover different methods to promote the work with reading aloud. The purpose of this study is therefore to review previous research that outlines different approaches to reading aloud to benefit students' reading skills. This purpose leads to the research question on which this study is based: What methods of reading aloud benefit the development of students' reading skills? Data collection consists of systematic searches through search strings in various databases such as ERIC (EBSCO), Swepub, Scopus and Diva. The research is both international and national. Thematic analysis is used to analyze the data collection. Based on the analysis, themes are identified and form our headings in the results section. The results of the study shows that interactive reading aloud is a method that benefits students' literacy development. Other factors such as the choice of book and the time of day also influence the promotion of reading development. The conclusion of this study is that interactive reading aloud, choice of book and time of day, among others, promotes literacy and comprehension. Active learning contributes to increased motivation among students.

For many years, Latin America has faced many socioeconomic problems. The lack of education and the limitation of access to information have been highly harmful to people with limited economic resources. As a consequence of these two inequalities, the crime ratio in the region has surpassed the global average ratio, and the development growth rate is low compared to other developing economies. Many educators around the world have concluded that the root of the problem is the bad structured educational systems in many of these countries, where not only the lack of well trained teachers, but also the limitation of opportunities is evident. As a result, Latin American people face many problems to compete and to excel in different fields in this globalized society. TutorEs is an online platform which desires to lessen the gap between the different socioeconomic status in terms of education quality. By providing open access to high quality educational material and taking advantage of information technology and the Internet; the company desires to empower people with the necessary skills and knowledge to succeed and to create a positive impact to the Latin American society as a whole. Besides providing teaching sessions, TutorES will also be able to create job opportunities through the offering of informal job positions, where people with the right skills can provide their service as tutors and receive a payment. The special feature of TutorES platform is the free online tutoring sessions provided by people who want to donate time and efforts to learners who cannot afford a learning session at an academic institution which requires a monthly payment for the service. TutorES believes that education is a powerful tool that will promote a positive change in the Latin American region.

Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2017-06-05T16:27:22Z No. of bitstreams: 1 Maytê Ramos Pires_.pdf: 2905670 bytes, checksum: c4824756c93f3e47c8bc0e1074a0838a (MD5) / Made available in DSpace on 2017-06-05T16:27:22Z (GMT). No. of bitstreams: 1 Maytê Ramos Pires_.pdf: 2905670 bytes, checksum: c4824756c93f3e47c8bc0e1074a0838a (MD5) Previous issue date: 2017-03-30 / CNPQ – Conselho Nacional de Desenvolvimento Científico e Tecnológico / Esta pesquisa teve como objetivo geral investigar e compreender os processos de debate nas sessões comentadas realizadas na Ocupação Pandorga e na Sala Redenção, pensados na perspectiva de construção da cidadania comunicativa cinematográfica. Os conceitos que fundamentaram a investigação, essenciais para a realização do diálogo com o empírico na construção da análise, foram: recepção de cinema, espacialidades, cinefilia, cidadania comunicativa pensada para âmbito da recepção cinematográfica, midiatização, mediações, apropriações midiáticas e cineclubismo. Na concretização da pesquisa, foi realizada uma contextualização de aspectos relativos à constituição do circuito de cinemas de Porto Alegre, particularizando aqueles onde se realizam debates, considerando vínculos com elementos relativos ao contexto cinematográfico mais amplo, cineclubes, ocupações urbanas e de modo específico, o cenário da Ocupação Pandorga e da Sala Redenção. A dimensão metodológica da investigação foi construída na promoção do diálogo entre os campos teórico e empírico, num ir e vir que levou a constantes mudanças na investigação até estabelecer seu núcleo no momento dos debates. Os procedimentos metodológicos trabalhados foram de pesquisas teórica, de contextualização e pesquisa da pesquisa. A pesquisa empírica foi conduzida a partir de observações de sessões comentadas de cinema e de entrevistas, de distintas modalidades. Os resultados obtidos na investigação indicam que ambos os espaços têm potencialidades na construção de ações cidadãs no campo do cinema e são apontadas sugestões para que tanto a Ocupação Pandorga quanto a Sala Redenção possam avançar na direção de sessões comentadas de cinema cidadãs, em termos de uma cidadania comunicativa pensada para o campo cinematográfico. / This research had as general goal to investigate and to understand the processes of debate in the commented sessions realized in Ocupação Pandorga and in Sala Redenção conceived into the perspective of the construction of a communicative cinematographic citizenship. The concepts that underpinned the investigation, essential for the realization of the dialogue with the empirical in the construction of the analysis, were: reception of cinema, spatialities, cinephilia, communicative citizenship thought for the scope of the cinematographic reception, mediatization, mediations, media appropriations and cineclubism. In the concretization of the research, a contextualization of aspects related to the constitution of the circuit of cinemas in Porto Alegre was carried out, particularizing those where debates take place, considering links with elements related to the wider cinematographic context, cineclubs, urban occupations and, specifically, Ocupação Pandorga and Sala Redenção scenario. The methodological dimension of the research was built on the promotion of dialogue between the theoretical and empirical fields, in a coming and going that led to constant changes in the research until it establishes its nucleus at the moment of the debates. The methodological procedures worked were of theoretical research, of contextualization and research of the research. The empirical research was conducted from observations of commented cinema sessions and occasional interviews, of different modalities. The results obtained in the investigation indicate that both spaces have potentialities in the construction of citizen actions in the field of cinema and suggestions are proposed in order that both Ocupação Pandorga and Sala Redenção can advance in the direction of commented sessions of citizen cinema, in terms of a communicative citizenship designed for the cinematographic field.

Made available in DSpace on 2016-04-29T13:18:06Z (GMT). No. of bitstreams: 1 Moema Galindo de Almeida Pinto.pdf: 462264 bytes, checksum: 4926c07d34c9df40576cad138aa31acd (MD5) Previous issue date: 2007-10-11 / The purpose of this study has been to investigate the relationship between saying and doing in natural environment, in a therapeutic session. Another aim has been to determine whether any change of behavior in the therapist would occur as result of the interview about the correspondence, employing to this effect a multiple baseline procedure. An adult therapist, two years after graduation, participated in the study, with the therapeutic sessions audio-recorded and transcribed, to be later subjected to four interviews with an average of (12) twelve situations about the criteria of behavior of the therapist. Three criteria selected from psychotherapy manuals (two concerning therapist desirable behavior and one of undesirable behavior), were used as a target of each interview. Having the target behavior for each interview been previously selected, the researcher narrated the preceding piece and inquired of the therapist what he had done in that situation, and compared the narrated responses with those observed. The results suggest that there is correspondence between narrated and observed behaviors. They have also shown that the narration requested in the procedure of multiple baselines improved the therapist performance according to the criteria of the literature. The results are discussed in terms of production of verbal correspondence and adjustments made in responding, that narration produces in the performance / O presente estudo teve como objetivo investigar a correspondência entre dizer e fazer em ambiente natural, em uma sessão terapêutica. Um segundo objetivo foi verificar se haveria alguma mudança no comportamento do terapeuta como efeito da entrevista sobre a correspondência, utilizando para isso um procedimento de linha de base múltipla. Participou deste estudo um terapeuta adulto, com 2 anos de formado, que teve de suas sessões terapêuticas gravadas em áudio e transcritas para posteriormente ser submetido a 4 entrevistas com uma média de 12 situações sobre esses critérios do comportamento do terapeuta. Três critérios selecionados a partir de manuais de psicoterapia (dois a respeito de comportamento desejáveis e um de comportamento indesejável do terapeuta) foram utilizados como alvo de cada entrevista. Selecionado o comportamento alvo para cada entrevista previamente, a pesquisadora relatava o trecho antecedente e perguntava ao terapeuta o que ele tinha feito naquela situação, e comparava as respostas relatadas com as respostas observadas. Os resultados indicam que há correspondência entre o comportamento relatado e o comportamento observado. Mostraram também que o relatar solicitado no procedimento de linha de base múltipla, melhorou o desempenho do terapeuta segundo os critérios da literatura. Os resultados são discutidos em termos de produção de correspondência verbal e de ajustes no responder que o relatar produz no desempenho

Com a heterogeneidade de tecnologias de comunicação sem fio presentes na borda de redes de acesso, serviços providos na Internet podem ser acessados de forma quasi ubíqua através de dispositivos móveis ou portáteis. O acesso a esses serviços, contudo, está associado a atrasos e rupturas frequentes na comunicação devido a razões inerentes à mobilidade do dispositivo, como: i) perda de sinal em locais onde há pouca ou nenhuma cobertura de acesso móvel; ii) erros no quadro de dados durante a transmissão e, consequentemente, perdas de pacotes, que podem ser ocasionados por interferência no sinal ou enfraquecimento deste pelo distanciamento do dispositivo em relação à Estação Base; iii) mudanças de endereços IP durante transmissões em andamento causadas pela migração do dispositivo entre diferentes redes. Como consequência, aplicações falham com a ruptura de comunicações orientadas a conexão. Tratar a mobilidade de forma transparente à aplicação é um dos desafios da Computação Móvel e Ubíqua que vem sendo pesquisado ao longo da última década. Soluções foram propostas para operarem desde a Camada de Enlace à Aplicação. Muitas delas, entretanto, exigem modificações na pilha de protocolos TCP/IP e adição de infraestrutura específica de rede no suporte à comunicação fim-a-fim. Além de elevar o custo das etapas de implantação e manutenção, estratégias intrusivas e dependentes de infraestrutura adicional podem não apresentar desempenho satisfatório. Nesse contexto, propomos tratar a mobilidade no nível da própria aplicação através de Sessões de Comunicação que não falham com atrasos e desconexões. Operando somente nos nós-fim e de modo transparente às Camadas adjacentes de Aplicação e Transporte, as sessões não requerem infraestrutura adicional para intermediar ou controlar a comunicação entre pares, tampouco modificações em protocolos legados da pilha TCP/IP. O conceito de Sessões Tolerantes a Rupturas é implementado através de uma API de propósito geral em sistemas Linux que estende a interface de Sockets. A API é, na prática, uma camada transparente sobre o Socket que provê Ciência de Mobilidade à aplicação através de mecanismos para: acompanhar a localização de nós ao longo da duração de uma sessão; detectar rupturas nas transmissões causadas pela mobilidade do nó ou de seu par remoto; suspender e retomar sessões de forma eficiente, segura e confiável. Experimentos conduzidos em ambientes emulados e reais com equipamentos de uso comercial mostram a eficiência das sessões. Além de introduzir baixa degradação na vazão fim-a-fim, rupturas na transmissão podem ser detectadas em microssegundos e sessões suspensas são reabertas em milissegundos. Com um desempenho superior a solução de mobilidade geral da Camada IP, as sessões não necessitam de adaptações de software em equipamentos de rede / Nowadays services available on the Internet can be accessed from mobile devices while they roam across heterogeneous wireless networks. Due to the inherent reasons of device mobility, however, the access to such services is frequently involved with delay and disruptions. The most common reasons are: i) losing radio signal at places where mobile access coverage area is not available; ii) frame error, losses, and fading on the radio signal when the mobile device moves away from the Base Station; iii) changes on the devices IP address over ongoing transmission, while the mobile node migrates among different wireless networks. As result, networked application fails with disruptions on TCP connections established in the mobile users path. Handling seamlessly mobility on the Internet is a technical challenge of the Mobile Computing Paradigm. It has been widely researched over the last decade. Several solutions have been proposed to work from the Link Layer to the Application Layer. Most of them, however, work intrusively and require modifications in the classical TCP/IP protocol stack, as well as rely on additional network infrastructure to support mobile end-to-end communication. Besides increasing the cost of deployment and maintenance, intrusive and infrastructure dependent strategies may not present suitable performance. In this sense, we devised an architecture to handle mobility at the Application level by means of communication sessions that do not fail with delay, disruption or disconnection. Such sessions work only at the end-systems in a such way that: are fully transparent to the adjacent layers of Transport and Application; do not require additional network infrastructure to forward and manage the communication between two mobile peers; and do not impose any modification on the legacy protocols from the TCP/IP stack. The concept of Disruption-Tolerant Sessions is implemented in Linux by means of a general purpose API extended from the Socket interface. Such API is a transparent layer placed on top of the Socket to provide mobility awareness to the Application Layer. To do so, session services are provided for: tracking mobile peers along the session duration; detecting disruptions over TCP connection caused by mobility of the local or remote peer; suspending and resuming sessions with efficiency, security and reliability. Experiments conducted in emulated and real systems (off-the-shelf hardware and open source software) showed the desired efficiency. Besides introducing little overhead on the goodput, disruptions are detected in a range of microseconds and suspended sessions are resumed in milliseconds. With performance greater than the general IP layer mobility solution, the proposed sessions do not require software adaptation in the core of the network infrastructure

<p>This thesis is a collection of seven papers reporting a research effort that started in January 1999. The theme of the thesis is interaction support for mobile CSCW (Computer Supported Cooperative Work). The interest in this theme is motivated by the trend towards a networked and nomadic society, the technical trends towards embedded, ubiquitous, and mobile technology, and the emergence of mobile CSCW settings. It is also motivated by current trends within the area of CSCW to focus on actual work practices, invisible and ubiquitous computer support, and mobile work settings where interaction with others is critical to get the work done.</p><p>For some time now mobile technology has been widely used to support dispersed mobile interaction, and recently the importance of co-located ”mobile meetings” to get the work done, has been recognized in the area of CSCW. However, current technology is not well suited when it comes to support interaction in mobile work settings across co-located and dispersed settings. Here, this problem is approached from an informatics perspective. Informatics can be described as a theory and design oriented study of information technology use. The scope of this thesis can be defined as understanding transformations of work practice through the use of mobile technology, and how it might be supported. The overall research question is: What are the specific needs of interaction support related to mobile meetings and dispersed interaction, how might these be supported, and what are the implications for current interaction models and support within CSCW? To answer this question several activities have been undertaken. This thesis contains empirical studies of mobile work among service technicians at Telia Nära, models of mobility and mobile meetings, and design and evaluations of a prototype system called RoamWare.</p><p>The overall conclusions related to the question stated in this thesis are that mobile interaction can be described as ongoing across mobile meetings, including both co-located face-to-face and dispersed interaction. Further, the interaction is maintained by the mobile workers through their efforts of re-establishing different threads of interaction across co-located and dispersed settings. Overall: There is a need to bridge co-located and dispersed meetings with sustained interaction support. Concerning the second part of the overall research question one conclusion is that sustained interaction across co-located and dispersed settings can be supported with mobile physical/virtual meetings support systems through the use of personal and public interaction histories. To illustrate and test this idea a prototype system called RoamWare was developed. However, evaluations of RoamWare revealed that synchronous support for sustained interaction divides users’ attention between co-located and dispersed interaction. As a consequence a second version of RoamWare was developed as an unobtrusive support for sustained interaction in between mobile meetings through seamless reestablishment of different threads of interaction, by offering support for converting interaction histories into project contexts. Finally, and according to the last part of the question stated above, this thesis concludes that current session management models need to be extended to handle sustained and dynamic sessions of interaction across co-located and dispersed mobile meetings and that, techniques for addressing groups need to be extended to enable dynamic addressing of participants in co-located mobile meeting. Finally, the exploration of how to support sustained interaction in between mobile meetings reveals important aspects to consider when trying to automatically frame spontaneous interaction with mobile technology.</p><p>Directions for future work include questions of how to design filters to support: maintenance, participation in, and negotiation about participation in between, different mobile meetings. Further, more work is needed related to how to capture spontaneous face-to-face interaction technically. Finally, new methods are needed to enable good evaluations of the impact of IT in mobile work settings.</p>