Distortion control for delay-sensitive sources

We investigate the problem of finding minimum-distortion policies for streaming delay-sensitive but distortion-tolerant data. We consider cross-layer approaches which exploit the coupling between presentation and transport layers. We make the natural assumption that the distortion function is convex and decreasing. We focus on a single source-destination pair and analytically find the optimum transmission policy when the transmission is done over an error-free channel. This optimum policy turns out to be independent of the exact form of the convex and decreasing distortion function. Then, for a packet-erasure channel, we analytically find the optimum open-loop transmission policy, which is also independent of the form of the convex distortion function. We then find computationally efficient closed-loop heuristic policies and show, through numerical evaluation, that they outperform the open-loop policy and have near optimal performance.

ClubADSL: When your neighbors are your friends

ADSL is becoming the standard form of residential and small-business broadband Internet access due to, primarily, its low deployment cost. These ADSL residential lines are often deployed with 802.11 Access Points (AP) that providewireless connectivity. Given the density of ADSL deployment, it is often possible for a residential wireless client to be in range of several other APs, belonging to neighbors, with ADSL connectivity. While the ADSL technology has showed evident limits in terms of capacity (with speeds ranging 1-10 Mbps), the short-range wireless communication can guarantee a muchhigher capacity (up to 20 Mbps). Furthermore, the ADSL links in the neighborhood are generally under-utilized, since ADSL subscribers do not connect 100% of the time. Therefore, it is possible for a wireless client to simultaneously connect to several APs in range and effectively aggregate their available ADSL bandwidth.In this paper, we introduce ClubADSL, a wireless client that can simultaneously connect to several APs in range on different frequencies and aggregate both their downlink and uplink capacity. ClubADSL is a software that runs locally on the client-side, and it requires neither modification to the existing Internet infrastructure, nor any hardware/protocol upgradesto the 802.11 local area network. We show the feasibility of ClubADSL in seamlessly transmitting TCP traffic, and validate its implementation both in controlled scenarios and with current applications over real ADSL lines. In particular we show that a ClubADSL client can greatly benefit from the aggregated download bandwidth in the case of server-client applications such as video streaming, but can also take advantage of the increased upload bandwidth greatly reducing download times with incentive-based P2P applications such as BitTorrent.

Digital storytelling: un’applicazione didattica per ripensare ai media attraverso i media

El presente trabajo de investigación propone un proyecto de investigación centrado en los pre-adolescentes para estudiar, a través deautobiografías digitales (digital storytelling, DST) producidas por ellos, laspracticas cultural-medial y las representaciones que ellos han construido sobre los medios, en relación con los contextos de uso significativos, como el hogar, la escuela o su grupo de par. Los medios forman parte de las actividades cotidianas de los niños quien los emplean en prácticas de socialización, aprendizaje, juego y de construcción de la identidad y del conocimiento. Los digital storytelling,insertados en el contexto escolar, serán empleados como metodología didácticapara la adquisición de competencias tecnológicas y como instrumento de lainvestigación. Los DST, como practica cultural de los chicos, constituirán nuestrocampo para la observación de las modalidades de uso de los medios por parte delos jóvenes y sus capacidad de recombinar lenguajes y construir contenidos. LosDST proporcionaran, además, la posibilidad de acceder al universo simbólicoinfantil para comprender el significado que las tecnologías tienen en sus cotidianidad

Elokuvien levittäminen Internetissä

Movie distribution on the Internet has become more common in recent years along with fast broadband internet connections. The problem so far has been that the greatest part of movie distribution on the Internet has been illegal. This is about to change because the major film distributors are finally starting to rent and sell movies more and more on the Internet due to their growing confidence in new copy protection methods. The importance of movie online distribution to the movie industry is still tiny but it is increasing rapidly as is investing in new business models and distribution methods in the USA and Europe. This thesis examines the basic concepts of online movie distribution, such as distribution techniques and copy protection, the main companies that rent and sell movies on the internet and their business models, the effects of movie piracy and non-commercial distribution channels. The intention was to provide the reader with an overview of different aspects of movie distribution on the Internet and its future. The conclusion was that movie distribution on the Internet will play a bigger financial part in the future although it was still too early to say just how significant that will be. We will probably see many corresponding distribution techniques, like peer-to-peer networks and streaming servers distributing and broadcasting movies to different end-user platforms like television, PC and portable media players. Internet distribution of movies will not revolutionize movie distribution in the next couple of years but it will make possible new efficient and inexpensive ways to distribute movies globally which will in turn increase the possibilities for revenue, especially for small independent movie producers and distributors.

Reference intervals for common carotid intima-media thickness measured with echotracking: relation with risk factors.

AIMS: Common carotid artery intima-media thickness (CCIMT) is widely used as a surrogate marker of atherosclerosis, given its predictive association with cardiovascular disease (CVD). The interpretation of CCIMT values has been hampered by the absence of reference values, however. We therefore aimed to establish reference intervals of CCIMT, obtained using the probably most accurate method at present (i.e. echotracking), to help interpretation of these measures. METHODS AND RESULTS: We combined CCIMT data obtained by echotracking on 24 871 individuals (53% men; age range 15-101 years) from 24 research centres worldwide. Individuals without CVD, cardiovascular risk factors (CV-RFs), and BP-, lipid-, and/or glucose-lowering medication constituted a healthy sub-population (n = 4234) used to establish sex-specific equations for percentiles of CCIMT across age. With these equations, we generated CCIMT Z-scores in different reference sub-populations, thereby allowing for a standardized comparison between observed and predicted ('normal') values from individuals of the same age and sex. In the sub-population without CVD and treatment (n = 14 609), and in men and women, respectively, CCIMT Z-scores were independently associated with systolic blood pressure [standardized βs 0.19 (95% CI: 0.16-0.22) and 0.18 (0.15-0.21)], smoking [0.25 (0.19-0.31) and 0.11 (0.04-0.18)], diabetes [0.19 (0.05-0.33) and 0.19 (0.02-0.36)], total-to-HDL cholesterol ratio [0.07 (0.04-0.10) and 0.05 (0.02-0.09)], and body mass index [0.14 (0.12-0.17) and 0.07 (0.04-0.10)]. CONCLUSION: We estimated age- and sex-specific percentiles of CCIMT in a healthy population and assessed the association of CV-RFs with CCIMT Z-scores, which enables comparison of IMT values for (patient) groups with different cardiovascular risk profiles, helping interpretation of such measures obtained both in research and clinical settings.

Uusien tuotantotapojen haasteet : esimerkkitapauksina mobiili-TV ja monimediaisuus YLE Uutisissa

Opinnäytetyön tavoitteena oli selvittää, millaisia ovat uusien tuotantotapojen haasteet uudenlaiselle sisällöntuotannolle ja uutisympäristölle. Monimediaisen tuotannon esimerkkitapauksiksi rajattiin mobiili-TV ja YLE Uutiset. Mobiili-TV:n tutkimusta varten kootulle testiryhmälle tehtiin subjektiivisen laadun kokemista mittaava MOS-testi (Mean Opinion Score), jossa selvitettiin testattavien mielipiteitä matkapuhelimen kautta esitettyjen videotiedostojen kuvan- ja äänenlaadusta sekä eri pakkaustapojen käyttökelpoisuudesta mobiili-TV:ssä. Testillä haettiin esille myös sisällöllisesti sopiva ja käyttökelpoinen suhde, jolla mobiili-TV:n lähetteen kokonaiskaistanleveys olisi kuvan ja äänen välillä hyvä jakaa. Lisäksi samalla testiryhmällä tutkittiin, mitä mobiili-TV:stä yleensä tiedetään, millaisena palvelu koetaan ja millaista sisältöä siihen kaivattaisiin. Tämän kuluttajatutkimuksen mukaan mobiili-TV:hen soveltuvimmiksi sisältötyypeiksi koettiin uutiset, ajankohtaisohjelmat ja osin urheilu. Mobiili-TV:ssä ei ole vielä paljoakaan tarjontaa, joten väline on suurelle yleisölle oikeastaan täysin tuntematon. Testiryhmän mielestä se voisi kuitenkin joissakin tilanteissa korvata tai täydentää perinteisen TV-vastaanottimen käyttöä. Mobiili-TV:n sisältötyyppitutkimuksen lisäksi tutkittiin YLE Uutisten sisällöntuotantomenettelyjä. Teemahaastattelujen avulla selvitettiin, millainen on toimituksen tuotantotapa, miten ylivälineellinen sisällöntuotanto siellä mahdollisesti toteutuu, millainen on sen mahdollinen mobiili-TV-palvelu ja miten siellä suhtaudutaan niin sanottuun kansalaisjournalismiin. Haastattelujen johtopäätöksinä YLE Uutisissa ei vielä toteudu aito ylivälineellinen tuotanto, mutta merkkejä muutoksesta on näkyvissä. Kansalaisjournalismin nousu on havaittu, mutta käytännön vastauksia siihen ei vielä ole. YLE Uutisten nykyinen 3G-matkapuhelimillakin käytettävä internet-TV-palvelu on toteutettu suoratoistopalveluna (engl. streaming), eikä vielä DVB-H-verkkotekniikkaa hyödyntäen, joten se on teknisesti melko matalalaatuista. Esimerkkinä toteutuneesta ylivälineellisestä tuotannosta on opinnäytetyössä esitelty Kansainvälisen Jean Sibelius -viulukilpailun monimediainen uutispalvelu. Lopuksi esitetään tutkimuksen pohjalta löytyneitä mahdollisuuksia, jotka tukevat YLE Uutisten tuotannon järjestämistä ylivälineelliseksi ja kansalaisten sisällöntuotantoa. aktivoivaksi.

Premissas historicas do surgimento e desenvolvimento dos mass-media nos paises lusofonos

A nossa investigacao esta dedicada a paises que falam essencialmente a lingua portuguesa, nao sera de admirar que a maioria dos livros por nos usados sejam de autores e ediccao portuguesa. No decorrer deste trabalho recorremos a livros e trabalhos academicos de autores como: Carvalho, Arons de: A Censura À Imprensa Na Época Marcelista; Minerva,Coimbra, 1999; Evora, Silvino Lopes: As fontes jornalísticas na televisão caboverdiana, ediccoes FCC, Universidade do Minho,2004; Fontcuberta: Mar de, A Notícia – Pistas para compreender o mundo; Editorial Notícias “Tradução de Fernando Cascais”,Lisboa, 1999; Mata, Maria José: A Autocrítica no Jornalismo – O ombudsman na imprensa nacional e estrangeira; Minerva Editora,Coimbra, 2002; Pigeat, Henri: Médias et Déontologie – Règles du jeu ou jeu sans règles; Presses Universitaires Francaises, Paris, 1997; Sodré, Nelson Werneck. História da imprensa no Brasil. 2ª ed., Rio de Janeiro: Graal, 1977; Sousa, Jorge Pedro: As Notícias e os seus Efeitos; Minerva Editora,Coimbra, 2000; Veiga Manuel: Cabo Verde insularidade e Literatura, editions Karthala, Paris, 1998; Bem como, um conjunto de leis e projectos de lei ligados a comunicacao social, e algumas entrevistas. Estrutura do trabalho: Esta tese e constituida de: introducao, tres capitulos, conclusao, bibliografia e alguns anexos num total de . Na introducao explica-se a escolha do tema, a sua actualidade, o objecto de investigacao e claro a sua inovacao. No primeiro capitulo estudamos o context do aparecimento dos media nos paises lusofonos nos exemplos de Cabo Verde, Brasil, e Portugal. No Segundo cappitulo, analizamos as leis, os processos de controlo e financiamento dos mass-media e a regulacao dos conteudos dos programas de radio e televisao. No terceiro capitulo, a situacao actual dos meios de comunicacao social e do Jornalismo na CPLP, nele esta tambem exposta a parte practica do trabalho ou seja a analize da relacao do publico com os media e o nivel de confianca do publico na informacao por eles veiculada.

Stoneley wave modeling in heterogeneous porous media with viscous pore fluids

We implemented Biot-type porous wave equations in a pseudo-spectral numerical modeling algorithm for the simulation of Stoneley waves in porous media. Fourier and Chebyshev methods are used to compute the spatial derivatives along the horizontal and vertical directions, respectively. To prevent from overly short time steps due to the small grid spacing at the top and bottom of the model as a consequence of the Chebyshev operator, the mesh is stretched in the vertical direction. As a large benefit, the Chebyshev operator allows for an explicit treatment of interfaces. Boundary conditions can be implemented with a characteristics approach. The characteristic variables are evaluated at zero viscosity. We use this approach to model seismic wave propagation at the interface between a fluid and a porous medium. Each medium is represented by a different mesh and the two meshes are connected through the above described characteristics domain-decomposition method. We show an experiment for sealed pore boundary conditions, where we first compare the numerical solution to an analytical solution. We then show the influence of heterogeneity and viscosity of the pore fluid on the propagation of the Stoneley wave and surface waves in general.

On commercial media bias

Within the spokes model of Chen and Riordan (2007) that allowsfor non-localized competition among arbitrary numbers of media outlets, we quantify the effect of concentration of ownership on qualityand bias of media content. A main result shows that too few commercial outlets, or better, too few separate owners of commercial outlets can lead to substantial bias in equilibrium. Increasing the number of outlets (commercial and non-commercial) tends to bring down this bias; but the strongest effect occurs when the number of owners is increased. Allowing for free entry provides lower bounds on fixed costs above which substantial commercial bias occurs in equilibrium.

Allergies aux produits de contraste radiologiques [Allergy to radiographic contrast media].

Allergy to radiographic contrast media Hypersensitivity reactions to radio-contrast media are common in the daily practice. These products are responsible for immediate (< or = 1 hour after administration) and non immediate (> 1 hour after administration) hypersensitivity reactions. A diagnostic work-up by an allergologist with skin tests and in some cases provocation tests is of value in reducing the risk of recurrent hypersensitivity reactions to iodinated contrast media. A careful selection of the patients is required because the incidence of breakthrough reactions is still concerning, even with proper premedication. Practical recommendations are presented in this article. For gadolinium-based contrast agents, data in the literature is not sufficient for suggesting guidelines.

Utilização dos New Media nas Empresas de Comunicação em São Vicente

Este trabalho científico refere-se aos New Media num contexto empresarial, demonstrando essa tecnologia como uma nova forma de comunicar. A delimitação é feita numa perspectiva da ilha de São Vicente, em Cabo Verde, concentrando assim nas empresas de comunicação. Objectiva-se verificar se essas ferramentas da Web 2.0 são utilizadas nesse contexto, se os funcionários são conhecedores dessa tecnologia, qual a prática na sua utilização e se sofrem algum tipo de influência social quando usam os New Media.

Os Media ao Serviço do Imaginário: uma Reflexão Sobre a Rtp Internacional e a Lusofonia

Neste trabalho, não pretendemos analisar detalhadamente a lógica de intervenção relacionada com o desenvolvimento do espaço Lusófono e com a criação da Comunidade dos Países de Língua Portuguesa. Iremos, simplesmente, examinar alguns elementos desta intervenção, nomeadamente no que diz respeito à criação de meios de comunicação especialmente concebidos para dar corpo a esta política. A RTP Internacional e a RTP África serão certamente os canais televisivos que mais visibilidade dão a esta intervenção política, mas o Estado Português tem vindo, também, a promover vários protocolos de cooperação na área da comunicação social. Assim, pretendemos concentrar-nos na lógica de produção e de distribuição de conteúdos televisivos portugueses para as comunidades e países de língua portuguesa e outras iniciativas dos governos portugueses que promovam a exportação e intercâmbio de produtos mediáticos em português. As pertinentes questões relacionadas com a análise da recepção dos produtos culturais não serão abordadas no âmbito deste ensaio.