Η δημοφιλής τάση για ασύρματη επικοινωνία συμβολίζει την ανάγκη μας για ανεξαρτησία και ευελιξία. Σε συνδυασμό με την έμφυτη ανάγκη του ανθρώπου για επικοινωνία, ανταλλαγή σκέψεων και εμπειριών, η τάση αυτή περιλαμβάνει τα τελευταία χρόνια την απαίτηση για ασύρματα πολυμέσα. Η ασύρματη επικοινωνία πολυμέσων έχει τη δυνατότητα να αλλάξει πολλές από τις παραμέτρους της καθημερινότητάς μας. Η πληθώρα των εφαρμογών που προσφέρονται περιορίζεται μόνο από τη δυνατότητα του ασύρματου καναλιού να διαθέσει πόρους, ενέργεια και χρόνο. Η χωρητικότητα του ασύρματου διαύλου επικοινωνίας είναι το κλειδί και η έρευνα εστιάζει στη βελτιστοποίηση της μετάδοσης εφαρμογών ροής βίντεο, αξιοποιώντας όσο το δυνατόν καλύτερα το ασύρματο κανάλι. Στα πλαίσια της διατριβής προτείνεται μια νέα αναλυτική μέθοδος δημιουργίας συνθετικών βίντεο ροών MPEG-4 που μεταδίδονται σε ένα ετερογενές ασύρματο περιβάλλον. Η κίνηση που δημιουργούν πολλαπλές ροές βίντεο μοντελοποιείται από μια αλυσίδα Μαρκόφ δύο διαστάσεων. Προκειμένου να διατηρηθεί η ποιότητα παρεχόμενης υπηρεσίας, προτείνεται ένας μηχανισμός μεταγωγής των ροών βίντεο με βάση τις πιθανότητες μετάβασης καταστάσεων του μοντέλου. Επιπλέον, παρουσιάζεται ένα αναλυτικό μοντέλο εκτίμησης της αλλοίωσης της αντιλαμβανόμενης ποιότητας κωδικοποιημένου βίντεο Η.264/AVC. Το μοντέλο αυτό αξιοποιεί τα ιδιαίτερα χαρακτηριστικά της κωδικοποίησης Η.264/AVC και ιδιαίτερα τις αλληλεξαρτήσεις μεταξύ των πλαισίων βίντεο, ώστε να εξασφαλίσει την ακριβή εκτίμηση της συνολικής αλλοίωσης. Η μελέτη περιλαμβάνει συνδυασμούς πιθανών σφαλμάτων στο ασύρματο κανάλι ώστε να αποδειχθεί η δυνατότητα εκτίμησης της αλλοίωσης από το προτεινόμενο μοντέλο σε κάθε συνθήκη του δικτύου. Στη συνέχεια, αναλύονται μηχανισμοί προγραμματισμού της μετάδοσης πακέτων βίντεο και διαφοροποίησης της σημαντικότητας των πακέτων με βάση τον αντίκτυπό τους στη συνολική αλλοίωση του βίντεο. Η σημασία κάθε πακέτου εκτιμάται από το προτεινόμενο μοντέλο εκτίμησης της αλλοίωσης. Εξασφαλίζεται, έτσι, η προσαρμογή του ρυθμού μετάδοσης του βίντεο στις διαφορετικές συνθήκες του δικτύου. Η αξιολόγηση του μοντέλου εκτίμησης επεκτείνεται ώστε να συμπεριλάβει το πρωτόκολλο 802.11e το οποίο διαθέτει μηχανισμούς διασφάλισης της ποιότητας υπηρεσίας. Τέλος, παρουσιάζονται αλγόριθμοι επιλογής βέλτιστων διαδρομών μεταξύ πηγής και παραλήπτη σε ασύρματα δίκτυα αισθητήρων πολυμέσων. Προτείνεται μια επέκταση του πρωτοκόλλου LEACH ώστε να είναι δυνατή η δρομολόγηση πακέτων βίντεο από πολλαπλές διαδρομές με στόχο τη μικρότερη δυνατή αλλοίωση της ποιότητας και την εξοικονόμηση ενέργειας στους κόμβους. / The popular trend for wireless communications marks our demand for freedom and flexibility. Recently, the inherent human need for communication and sharing of ideas and experiences has been enriched with the need for wireless multimedia. Wireless multimedia communications have the ability to alter several parameters of our daily life. The great variety of offered services is only limited by the available resources of the wireless medium. The key is the capacity of the wireless medium and this research focuses on optimizing the video traffic while fully utilizing the wireless channel. This thesis introduces a new analytical method of creating synthetic MPEG-4 video streams over heterogeneous wireless networks. The aggregate video traffic generated by multiple wireless video sources is modeled by a two-dimensional Marcov chain. In order to achieve a guaranteed quality of service, a handoff mechanism is proposed based on the state transition probabilities of the statistical model. Moreover, an analytical distortion prediction model for H264/AVC coded video is presented. In order to precisely estimate the received video distortion, the proposed model utilizes the inherent characteristics of H.264/AVC coding and in particular, the correlation among neighboring video frames. The distortion prediction model’s ability to estimate the received video distortion is studied under different channel conditions. Hence, complex combinations of errors due to the wireless channel are considered in this thesis. Moreover, an analysis of video packet scheduling algorithms and traffic differentiation schemes, based on the video packet’s impact to the overall video distortion, is included. The importance of each video packet is estimated by the proposed distortion prediction model. Therefore, the transmission rate of a video source can be adapted to the varying wireless channel conditions. The evaluation of the model has been extended in order to include the study of the 802.11e standard, which incorporates mechanisms for guaranteeing quality of service. Finally, the thesis proposes algorithms for optimised video multipath routing in wireless multimedia sensor networks. A proposed extension of the LEACH protocol is implemented that ensures multipath video packet routing. Thus, significantly improved received video distortion and power consumption in the wireless sensor nodes, is achieved.

<p>In September of 2011 protestors filled the streets of New York City&rsquo;s Wall Street Financial District as part of the social movement known as Occupy Wall Street. Prior to their protests in the streets, Occupy Wall Street was a movement that originated and spread online through various social media such as Facebook, YouTube, Twitter, and interactive webpages. The strategy of using Internet communication as a tool for activism is not new. Social movements since the 1990s have utilized the Internet. </p><p> The growing use of Web 2.0 technologies in our everyday lives is a topic that is not yet fully understood or researched by anthropologists, nor is its potential for ethnographic research fully realized. This thesis addresses both of these points by presenting a case study of how, as anthropologists, we can collect data from both the online and in-person presences of a group. </p><p> This thesis focuses on the social movement, Occupy Wall Street, because of its beginnings and continuing activity online. In-person data of the Occupy Wall Street movement were collected at Occupy movements in Flint, Michigan and New York City, New York using traditional ethnographic methods such as interviews and participant observation. Online data were collected using computer scripts (programs that automate computer tasks), that recursively downloaded websites onto my personal, locally owned hard drive. Once the online data was collected, I also used computer scripts to filter through data and locate phenomena on the websites that I had chosen to focus. By analyzing both online and in-person data I am able to gain a more holistic view and new ways of understanding social movements. </p>

<p> The purpose of this quantitative experimental study was to test the impact of three learning interventions on student learning and satisfaction when the interventions were embedded in the instructional design of case-based, Computer-Assisted Instruction (CAI) modules for learning liver pathology in an in-class, self-study, laboratory exercise during a Year-2 medical school Pathology course. The hypothesis was that inclusion of the learning interventions would enhance student satisfaction in using the CAI and improve subsequent CAI-directed exam performance. Three learning interventions were studied, including the use of microscopic virtual slides instead of only static images, the use of interactive image annotations instead of only still annotations, and the use of guiding questions before presenting new information. Students were randomly assigned to with one of eight CAI learning modules configured to control for each of the three learning interventions. Effectiveness of the CAI for student learning was assessed by student performance on questions included in subsequent CAI-directed exams in a pretest and on posttests immediately after the lab exercise, at two weeks and two months. Student satisfaction and perceived learning was assessed by a student survey. </p><p> Results showed that the learning interventions did not improve subsequent student exam performance, although satisfaction and perceived learning with use of the CAI learning modules was enhanced. Student class rank was evaluated to determine if the learning interventions might have a differential effect based on class rank, but there were no significant differences. Class rank at the time of the lab exercise was itself the strongest predictor of exam performance. </p><p> The findings suggest that the addition of virtual slides, interactive annotations and guiding questions as learning interventions in self-study, case-based CAI for learning liver pathology in a medical class room setting are not likely to increase performance on subsequent MCQ-based exams, but student satisfaction with use of the CAI can be enhanced, which could provide to be an incentive for students to use similar CAI learning modules for future self-directed learning.</p>

Wireless communication is a rapidly growing field with many of its aspects undergoing constant enhancement. The use of cross-layer design (CLD) in current technologies has improved system performance in terms of Quality-of-Services (QoS) guarantees. While multimedia transmission is difficult to achieve, CLD is capable of incorporating techniques to achieve multimedia transmission without high complexity. Many systems have incorporated some form of adaptive transmission when using a cross-layer design approach. Various challenges must be overcome when transmitting multimedia traffic; the main challenge being that each traffic type, namely voice; image; and data, have their own transmission QoS; delay; Symbol Error Rate (SER); throughput; and jitter requirements. Recently cross-layer design has been proposed to exchange information between different layers to optimize the overall system performance. Current literature has shown that the application layer and physical layer can be used to adequately transmit multimedia over fading channels. Using Reed-Solomon coding at the application layer and Rate Adaption at the physical layer allows each media type to achieve its QoS requirement whilst being able to transmit the different media within a single packet. The following dissertation therefore strives to improve traffic through-put by introducing an unconventional rate adaption scheme and by using power adaption to achieve Symbol Error Rate (SER) QoS in multimedia transmission. Firstly, we introduce a system which modulates two separate sets of information with different modulation schemes. These two information sets are then concatenated and transmitted across the fading channel. The receiver uses a technique called Blind Detection to detect the modulation schemes used and then demodulates the information sets accordingly. The system uses an application layer that encodes each media type such that their QoS, in terms of SER, is achieved. Simulated results show an increase in spectral efficiency and the system achieves the required Symbol Error Rate constraint at lower Signal to Noise Ratio (SNR) values. The second approach involves adapting the input power to the system rather than adapting the modulation scheme. The two power adaptive schemes that are discussed are Water- Filling and Channel Inversion. Channel Inversion allows the SER requirement to be maintained for low SNR values, which is not possible with Rate Adaption. Furthermore, the system uses an application layer to encode each media type such that their QoS is achieved. Simulated results using this design show an improvement in through-put and the system achieves the SER constraint at lower SNR values. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2013.

Thesis (Ph. D.)--University of Hawaii at Manoa, 2003. / Includes bibliographical references (leaves 142-151). Also available via World Wide Web.

Thesis (M.S.)--Rochester Institute of Technology, 2006. / Typescript. Includes bibliographical references (p. 158-168).

x, 160 p. : ill. (some col.) / Although the web appears to be a welcoming space for women, online spaces--like offline spaces--are rendered female through associations with the personal/private, embodiment, or an emphasis on intimacy. As such, these spaces are marked, marginalized, and often dismissed. Using an explicitly interdisciplinary approach that combines cultural studies models with feminist theory, new media studies, and performance, Beyond Resistance uses fandom as a way to render visible the invisible ways that repressive discourses of gender are woven throughout digital culture. I examine a variety of online fan practices that use popular media to perform individual negotiations of repressive ideologies of sex and gender, such as fan-authored fiction, role-playing games, and vids and machinima--digital videos created from re-editing television and video game texts. Although many of these negotiations are potentially resistive, I demonstrate how that potential is being limited and redirected in ways that actually reinforce constructions of gender that support the dominant culture. The centrality of traditional notions of sex and gender in determining the value of fan practices, through both popular representation and critical analysis, serves as a microcosm of how discourses of gender are operating within digital culture to support the continued gendering of the public and private spheres within digital space. This gendering contributes to the ongoing subordination of women under patriarchy by marginalizing or dismissing their concerns, labor, and cultural tastes. / Committee in charge: Priscilla Ovalle, Chairperson; Kathleen Karlyn, Member; Michael Aronson, Member; Kate Mondloch, Outside Member

abstract: The increased risk of falling and the worse ability to perform other daily physical activities in the elderly cause concern about monitoring and correcting basic everyday movement. In this thesis, a Kinect-based system was designed to assess one of the most important factors in balance control of human body when doing Sit-to-Stand (STS) movement: the postural symmetry in mediolateral direction. A symmetry score, calculated by the data obtained from a Kinect RGB-D camera, was proposed to reflect the mediolateral postural symmetry degree and was used to drive a real-time audio feedback designed in MAX/MSP to help users adjust themselves to perform their movement in a more symmetrical way during STS. The symmetry score was verified by calculating the Spearman correlation coefficient with the data obtained from Inertial Measurement Unit (IMU) sensor and got an average value at 0.732. Five healthy adults, four males and one female, with normal balance abilities and with no musculoskeletal disorders, were selected to participate in the experiment and the results showed that the low-cost Kinect-based system has the potential to train users to perform a more symmetrical movement in mediolateral direction during STS movement. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2016

abstract: Long before “fake news” dominated the conversation within and about the media, media literacy advocates have championed the need for media literacy education that provides the tools for people to understand, analyze, and evaluate media messages. That the majority of U.S. adults now consume news on social media underscores the importance for students of all ages to be critical users of media. Furthermore, the affordances of social media to like, comment, and share news items within one’s network increases an individual’s responsibility to ascertain the veracity of news before using a social media megaphone to spread false information. Social media’s shareability can dictate how information spreads, increasing news consumers’ role as a gatekeeper of information and making media literacy education more important than ever. This research examines the media literacy practices that news consumers use to inform their gatekeeping decisions. Using a constant comparative coding method, the author conducted a qualitative analysis of hundreds of discussion board posts from adult participants in a digital media literacy Massive Open Online Course (MOOC) to identify major themes and examine growth in participants’ sense of responsibility related to sharing news information, their feeling of empowerment to make informed decisions about the media messages they receive, and how the media literacy tools and techniques garnered from the MOOC have affected their daily media interactions. Findings emphasize the personal and contextual nature of media literacy, and that those factors must be addressed to ensure the success of a media literacy education program. / Dissertation/Thesis / Doctoral Dissertation Journalism and Mass Communication 2018

This dissertation examines the strategic practice of virtual racial embodiment, as a case study of African Americans attempting to complicate current constructions of race and social justice in new media. I suggest that dominant racial constructions online teeter between racial stereotypes and the absence of race. Virtual racial classification and racial stereotypes of criminality and limited interaction with communication technologies prevalent in the digital divide literature frame the dominant online culture, which purports a Universalist ideal that avoids race through which racial hierarchy is nevertheless articulated. Based on qualitative and quantitative analyses—fieldwork, interviews with Black website founders, and an online survey—this case study provides an analytical framework that situates African Americans’ negotiations of race within everyday online discourse. I suggest that the strategy of racial embodiment has a sociohistorical and cultural basis in the racial and political strategies of offline African American communities. This study approaches these matters by locating political message board members’ agency in creating a safe space for daily critical discussions of race. Virtual safe spaces allow users to address social injustices, parse popular constructions of race, project respectability, and explore complex definitions of blackness. Ethnographic material drawn from the observation of four mainstream Black websites’ political message boards within the time frame of 2007–2008 provides information to discuss the unofficial message board practices I identify as safe house practices. I introduce the conceptual metaphor of safe house based on the physical and symbolic safe house of enslaved Africans of the antebellum era and their twentieth- and twenty-first-century successors—neighborhood meeting places, barbershops, and book stores. As a result of the analysis of the ethnographic material, I suggest racial embodiment is the transference of offline practices steeped in historic political and cultural practices of the Black community into online interactions. I use the Bourdieuan concept of the habitus to conceptualize the historical significance of the African American community’s virtual racial embodiment. I propose that this racial embodiment evidenced in the safe house practices exemplifies a dynamic Black habitus wherein black people exercise the ability to redefine black identity and community.