10 resultados para Instant messaging

em Helda - Digital Repository of University of Helsinki


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In recent years, XML has been widely adopted as a universal format for structured data. A variety of XML-based systems have emerged, most prominently SOAP for Web services, XMPP for instant messaging, and RSS and Atom for content syndication. This popularity is helped by the excellent support for XML processing in many programming languages and by the variety of XML-based technologies for more complex needs of applications. Concurrently with this rise of XML, there has also been a qualitative expansion of the Internet's scope. Namely, mobile devices are becoming capable enough to be full-fledged members of various distributed systems. Such devices are battery-powered, their network connections are based on wireless technologies, and their processing capabilities are typically much lower than those of stationary computers. This dissertation presents work performed to try to reconcile these two developments. XML as a highly redundant text-based format is not obviously suitable for mobile devices that need to avoid extraneous processing and communication. Furthermore, the protocols and systems commonly used in XML messaging are often designed for fixed networks and may make assumptions that do not hold in wireless environments. This work identifies four areas of improvement in XML messaging systems: the programming interfaces to the system itself and to XML processing, the serialization format used for the messages, and the protocol used to transmit the messages. We show a complete system that improves the overall performance of XML messaging through consideration of these areas. The work is centered on actually implementing the proposals in a form usable on real mobile devices. The experimentation is performed on actual devices and real networks using the messaging system implemented as a part of this work. The experimentation is extensive and, due to using several different devices, also provides a glimpse of what the performance of these systems may look like in the future.

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In recent years, XML has been accepted as the format of messages for several applications. Prominent examples include SOAP for Web services, XMPP for instant messaging, and RSS and Atom for content syndication. This XML usage is understandable, as the format itself is a well-accepted standard for structured data, and it has excellent support for many popular programming languages, so inventing an application-specific format no longer seems worth the effort. Simultaneously with this XML's rise to prominence there has been an upsurge in the number and capabilities of various mobile devices. These devices are connected through various wireless technologies to larger networks, and a goal of current research is to integrate them seamlessly into these networks. These two developments seem to be at odds with each other. XML as a fully text-based format takes up more processing power and network bandwidth than binary formats would, whereas the battery-powered nature of mobile devices dictates that energy, both in processing and transmitting, be utilized efficiently. This thesis presents the work we have performed to reconcile these two worlds. We present a message transfer service that we have developed to address what we have identified as the three key issues: XML processing at the application level, a more efficient XML serialization format, and the protocol used to transfer messages. Our presentation includes both a high-level architectural view of the whole message transfer service, as well as detailed descriptions of the three new components. These components consist of an API, and an associated data model, for XML processing designed for messaging applications, a binary serialization format for the data model of the API, and a message transfer protocol providing two-way messaging capability with support for client mobility. We also present relevant performance measurements for the service and its components. As a result of this work, we do not consider XML to be inherently incompatible with mobile devices. As the fixed networking world moves toward XML for interoperable data representation, so should the wireless world also do to provide a better-integrated networking infrastructure. However, the problems that XML adoption has touch all of the higher layers of application programming, so instead of concentrating simply on the serialization format we conclude that improvements need to be made in an integrated fashion in all of these layers.

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Wireless technologies are continuously evolving. Second generation cellular networks have gained worldwide acceptance. Wireless LANs are commonly deployed in corporations or university campuses, and their diffusion in public hotspots is growing. Third generation cellular systems are yet to affirm everywhere; still, there is an impressive amount of research ongoing for deploying beyond 3G systems. These new wireless technologies combine the characteristics of WLAN based and cellular networks to provide increased bandwidth. The common direction where all the efforts in wireless technologies are headed is towards an IP-based communication. Telephony services have been the killer application for cellular systems; their evolution to packet-switched networks is a natural path. Effective IP telephony signaling protocols, such as the Session Initiation Protocol (SIP) and the H 323 protocol are needed to establish IP-based telephony sessions. However, IP telephony is just one service example of IP-based communication. IP-based multimedia sessions are expected to become popular and offer a wider range of communication capabilities than pure telephony. In order to conjoin the advances of the future wireless technologies with the potential of IP-based multimedia communication, the next step would be to obtain ubiquitous communication capabilities. According to this vision, people must be able to communicate also when no support from an infrastructured network is available, needed or desired. In order to achieve ubiquitous communication, end devices must integrate all the capabilities necessary for IP-based distributed and decentralized communication. Such capabilities are currently missing. For example, it is not possible to utilize native IP telephony signaling protocols in a totally decentralized way. This dissertation presents a solution for deploying the SIP protocol in a decentralized fashion without support of infrastructure servers. The proposed solution is mainly designed to fit the needs of decentralized mobile environments, and can be applied to small scale ad-hoc networks or also bigger networks with hundreds of nodes. A framework allowing discovery of SIP users in ad-hoc networks and the establishment of SIP sessions among them, in a fully distributed and secure way, is described and evaluated. Security support allows ad-hoc users to authenticate the sender of a message, and to verify the integrity of a received message. The distributed session management framework has been extended in order to achieve interoperability with the Internet, and the native Internet applications. With limited extensions to the SIP protocol, we have designed and experimentally validated a SIP gateway allowing SIP signaling between ad-hoc networks with private addressing space and native SIP applications in the Internet. The design is completed by an application level relay that permits instant messaging sessions to be established in heterogeneous environments. The resulting framework constitutes a flexible and effective approach for the pervasive deployment of real time applications.

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I boken behandlas nya kommunikationstekniker och olika marknadsföringsmetoder som har uppkommit till följd av den tekniska utvecklingen. Marknadsföring via de nya kommunikationskanalerna har givit upphov till vissa olägenheter för mottagarna. Olägenheterna som mottagarna förorsakas vid marknadsföring via de nya teknikerna kan delas in i tre kategorier; 1) meddelandet förorsakar kostnader för mottagaren, 2) meddelandet hindrar mottagaren samt 3) meddelandet upplevs vara påträngande och utgöra ett intrång i mottagarens privatliv. Under de senaste åren har det förekommit hektiska lagstiftningsåtgärder på många håll i världen. Såväl enskilda stater, nationella myndigheter samt internationella organisationer har utarbetat regler om marknadsföring via de nya teknikerna. En av kärnfrågorna i regleringen är huruvida man skall ha ett system med ”opt-in” eller ”opt-out”. En opt-in-lösning innebär att marknadsföraren måste inhämta mottagarens samtycke på förhand, medan en opt-out-lösning innebär att det är tillåtet att sända marknadsföring om inte mottagaren motsatt sig detta. Enligt gällande lagstiftning faller marknadsföring via följande tre tekniker under opt-in: automatiserade uppringningssystem, telefax samt e-post. Det huvudsakliga syftet med avhandlingen är att utreda om nuvarande opt-in-lista är tillräckligt omfattande med beaktande av de olägenheter som marknadsföring via de nya teknikerna förorsakar, eller om den bör utvidgas. I genomgången av marknadsföring via nya tekniker har marknadsföring via bl.a. följande tekniker undersökts: Internet (www-sidor), reklamfönster, reklambanner, e-post, mobiltelefon, telefax, bloggar, RSS, Instant Messaging samt Internettelefoni. Vid sidan av nya tekniker har även vissa ”traditionella” marknadsföringsmetoder undersökts, i syfte att utreda huruvida även de bör falla in under en opt-in-lösning. De traditionella marknadsföringsmetoder som ingår i avhandlingen är hemförsäljning, telemarketing, TV- och radioreklam samt adresserad och oadresserad direktreklam. En annan central del i avhandlingen är frågan hur påföljdssystemet vid överträdelser av opt-in-bestämmelserna bör utformas. Hur skall de enskilda mottagarna få ersättning för de kostnader de åsamkats av marknadsföringen? Är det dags att införa straffskadestånd i Finland? Hög tid att även Finland får grupptalan? Kan tvisterna avgöras virtuellt via domstolar on-line eller ODR?

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This study evaluates how the advection of precipitation, or wind drift, between the radar volume and ground affects radar measurements of precipitation. Normally precipitation is assumed to fall vertically to the ground from the contributing volume, and thus the radar measurement represents the geographical location immediately below. In this study radar measurements are corrected using hydrometeor trajectories calculated from measured and forecasted winds, and the effect of trajectory-correction on the radar measurements is evaluated. Wind drift statistics for Finland are compiled using sounding data from two weather stations spanning two years. For each sounding, the hydrometeor phase at ground level is estimated and drift distance calculated using different originating level heights. This way the drift statistics are constructed as a function of range from radar and elevation angle. On average, wind drift of 1 km was exceeded at approximately 60 km distance, while drift of 10 km was exceeded at 100 km distance. Trajectories were calculated using model winds in order to produce a trajectory-corrected ground field from radar PPI images. It was found that at the upwind side from the radar the effective measuring area was reduced as some trajectories exited the radar volume scan. In the downwind side areas near the edge of the radar measuring area experience improved precipitation detection. The effect of trajectory-correction is most prominent in instant measurements and diminishes when accumulating over longer time periods. Furthermore, measurements of intensive and small scale precipitation patterns benefit most from wind drift correction. The contribution of wind drift on the uncertainty of estimated Ze (S) - relationship was studied by simulating the effect of different error sources to the uncertainty in the relationship coefficients a and b. The overall uncertainty was assumed to consist of systematic errors of both the radar and the gauge, as well as errors by turbulence at the gauge orifice and by wind drift of precipitation. The focus of the analysis is error associated with wind drift, which was determined by describing the spatial structure of the reflectivity field using spatial autocovariance (or variogram). This spatial structure was then used with calculated drift distances to estimate the variance in radar measurement produced by precipitation drift, relative to the other error sources. It was found that error by wind drift was of similar magnitude with error by turbulence at gauge orifice at all ranges from radar, with systematic errors of the instruments being a minor issue. The correction method presented in the study could be used in radar nowcasting products to improve the estimation of visibility and local precipitation intensities. The method however only considers pure snow, and for operational purposes some improvements are desirable, such as melting layer detection, VPR correction and taking solid state hydrometeor type into account, which would improve the estimation of vertical velocities of the hydrometeors.

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Event-based systems are seen as good candidates for supporting distributed applications in dynamic and ubiquitous environments because they support decoupled and asynchronous many-to-many information dissemination. Event systems are widely used, because asynchronous messaging provides a flexible alternative to RPC (Remote Procedure Call). They are typically implemented using an overlay network of routers. A content-based router forwards event messages based on filters that are installed by subscribers and other routers. The filters are organized into a routing table in order to forward incoming events to proper subscribers and neighbouring routers. This thesis addresses the optimization of content-based routing tables organized using the covering relation and presents novel data structures and configurations for improving local and distributed operation. Data structures are needed for organizing filters into a routing table that supports efficient matching and runtime operation. We present novel results on dynamic filter merging and the integration of filter merging with content-based routing tables. In addition, the thesis examines the cost of client mobility using different protocols and routing topologies. We also present a new matching technique called temporal subspace matching. The technique combines two new features. The first feature, temporal operation, supports notifications, or content profiles, that persist in time. The second feature, subspace matching, allows more expressive semantics, because notifications may contain intervals and be defined as subspaces of the content space. We also present an application of temporal subspace matching pertaining to metadata-based continuous collection and object tracking.

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This thesis consists of four research papers and an introduction providing some background. The structure in the universe is generally considered to originate from quantum fluctuations in the very early universe. The standard lore of cosmology states that the primordial perturbations are almost scale-invariant, adiabatic, and Gaussian. A snapshot of the structure from the time when the universe became transparent can be seen in the cosmic microwave background (CMB). For a long time mainly the power spectrum of the CMB temperature fluctuations has been used to obtain observational constraints, especially on deviations from scale-invariance and pure adiabacity. Non-Gaussian perturbations provide a novel and very promising way to test theoretical predictions. They probe beyond the power spectrum, or two point correlator, since non-Gaussianity involves higher order statistics. The thesis concentrates on the non-Gaussian perturbations arising in several situations involving two scalar fields, namely, hybrid inflation and various forms of preheating. First we go through some basic concepts -- such as the cosmological inflation, reheating and preheating, and the role of scalar fields during inflation -- which are necessary for the understanding of the research papers. We also review the standard linear cosmological perturbation theory. The second order perturbation theory formalism for two scalar fields is developed. We explain what is meant by non-Gaussian perturbations, and discuss some difficulties in parametrisation and observation. In particular, we concentrate on the nonlinearity parameter. The prospects of observing non-Gaussianity are briefly discussed. We apply the formalism and calculate the evolution of the second order curvature perturbation during hybrid inflation. We estimate the amount of non-Gaussianity in the model and find that there is a possibility for an observational effect. The non-Gaussianity arising in preheating is also studied. We find that the level produced by the simplest model of instant preheating is insignificant, whereas standard preheating with parametric resonance as well as tachyonic preheating are prone to easily saturate and even exceed the observational limits. We also mention other approaches to the study of primordial non-Gaussianities, which differ from the perturbation theory method chosen in the thesis work.

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Les participes présents apparaissent, entre autres, dans des constructions à prédication seconde détachées : (1) Intervenant hier soir à Ankara, […], Vladimir Poutine s’est risqué à […]. (Le Figaro 7.12.2004 : 4) Même si les gérondifs, formes adverbiales du verbe (« converbes », cf. Haspelmath & König 1995), n’ont pas d’incidence nominale, contrairement aux participes présents, formes adjectivales du verbe, et ne sont donc pas toujours comptés parmi les constructions à prédication seconde (p.ex. Neveu 1998), les deux ont des emplois assez proches : dans des énoncés du type (2a-b), le participe adjoint peut être paraphrasé par un gérondif, même si son statut fonctionnel n’est pas le même (Halmøy, 2003 : 156-157) : (2a) Arrivant à Paris, Emile a proposé à Léa de [...]. (2b) En arrivant à Paris, Emile a proposé à Léa de[...]. (Halmøy, 2003 : 157) Le finnois ne connaît ni ce genre de constructions détachés ni de forme appelée ‘gérondif’, et les deux participes présents finnois (actif et passif) ne correspondent jamais à un participe présent détaché français : en plus de subordonnées, on trouve à leur place le deuxième infinitif, soit à l’inessif, soit à l’instructif, formes nominales qu’on trouve également dans la traduction des gérondifs : (3a) […] ? me demanda-t-elle sèchement en me montrant l’une des lignes incriminées. (Nothomb, p. 62) […] : hän kysyi minulta kuivakkaasti näyttäen erästä Unajin moittimaa riviä. (Suni, p. 4) (3b) L’espace d’un instant, il sourit, croyant que […] je m’étais trompée de commodités. (Nothomb, p. 138-139) Hetken hän hymyili luullen, että minä […] olin erehtynyt mukavuuslaitoksesta. (Suni, p. 94) : Dans cette communication, nous examinerons quatre traductions littéraires en nous demandant dans quels cas et de quelle manière la différence entre le participe et le gérondif a éventuellement été prise en considération.

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Within the field of philosophy, animals have traditionally been studied from two perspectives: that of self-knowledge and that of ethics. The analysis of the differences between humans and animals has served our desire to understand our own specificity, whereas ethical discussions have ultimately aimed at finding the right way to treat animals. This dissertation proposes a different way of looking at non-human animals: it investigates the question of how non-human animals appear to us humans in our perceptual experience. The analysis focuses on the empathetic, embodied understanding of animals diverse movements and other expressions. The theoretical point of departure for the research is phenomenological philosophy, in particular Maurice Merleau-Ponty s phenomenology of the body. Edmund Husserl s and Edith Stein s analyses of empathy and embodiment are also crucial to the work. In this tradition, empathy means understanding the other s experience through her bodily expressions and seeing the other body as living, as well as motivated and directed towards the surrounding world. The dissertation both explicates and criticizes the earlier phenomenological notions of empathy and human specificity. In order to elucidate the fundamental structures of our experience of non-human animals, it also applies the phenomenological method, which consists of a phenomenological reduction and a free variation of the different aspects of experience. It is shown that our experiences of non-human animals involve a recognition of both similarities and differences. This recognition, however, is not primarily based on intellectual comparisons but is lived as an embodied relationship to another body, and its manifestations vary from one instant to the next. The analysis also reveals that the object of empathy is not the other s experience as such, not even as it is manifested by the other s movements, but rather the other s embodied situation, enriched by elements that remain outside the scope of the other s experience. The dissertation shows that human existence is intertwined with the existence of non-human animals on four levels: those of empathetic sensations, reciprocal communication, experience of the surrounding world and self-definitions. The animals different modes of perception prove to expand our understanding of what is perceivable and how things can be perceived. The presence of non-human animals in our perceptual world is revealed as something that both shows us the limits of our own embodiment and enables us to overcome these limits in empathetic acts. Finally, it is demonstrated that the life of non-human animals is intertwined with ours in a far more complex way than has been presupposed in traditional descriptions of human-animal differences.

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Aim of this master's thesis paper for consumer economics, is to research gambling advertisements in Finland over a period of 35 years, from 1970 to 2006. Veikkaus Oy (later Veikkaus), was founded in 1940, as one of the three licensed gambling organizations in Finland. Material for the current research comprised 1494 advertisements published by Veikkaus in newspapers and magazines at that time. Veikkaus has the exclusive licence to organize lotto games, sport games, instant games and other draw games in Finland. The other two operators, The Finnish Slot Machine Association RAY and Fintoto (on-track horse betting), were not included in the current analysis. This study has been completed according to research contract and grand by the Finnish Foundation for Gaming Research (Pelitoiminnan tutkimussäätiö). In general, advertisements reflect surrounding culture and time, and their message is built on stratified meanings, symbols and codes. Advertising draws the viewer's attention, introduces the advertised subject, and finally, affects the individual's consumption habits. However, advertisements not only work on individual level, but also influence public perception of the advertised product. Firstly, in order to assess gambling as a phenomenon, this paper discusses gambling as consumer behaviour, and also reviews history of gambling in Finland. Winning is a major feature of gambling, and dreaming about positive change of life is a centre of most gambling ads. However, perceived excitement through risk of losing can also be featured in gambling ads. Secondly, this study utilizes Veikkaus’ large advertising archives, were advertising data is analyzed by content analysis and the semiotic analysis. Two methods have been employed to support analyzing outcome in a synergistic way. Content analysis helps to achieve accuracy and comprehensiveness. Semiotic analysis allows deeper and more sensitive analysis to emerged findings and occurrences. It is important to understand the advertised product, as advertising is bound to the culture and time. Hence, to analyze advertising, it is important to understand the environment where the ads appear. Content analysis of Veikkaus data discovered the main gambling and principal advertisement style for each.period. Interestingly, nearly half of Veikkaus’ advertisements promoted topic other than “just winning the bet”. Games of change, like Lotto, typically advertised indirectly represented dreams about winning. In the category of skill gambling, features were represented as investment, and the excitement of sporting expertise was emphasized. In addition, there were a number of gambling ads that emphasize social responsibility of Veikkaus as a government guided organization. Semiotic methods were employed to further elaborate on findings of content analysis. Dreaming in the advertisements was represented by the product of symbols, (e.g. cars and homes) that were found to have significance connection with each other. Thus, advertising represents change of life obtained by the winning. Interestingly, gambling ads promoting jackpots were often representing religious symbolisms. Ads promoting social responsibility were found to be the most common during economical depression of the 90’s. Deeper analysis showed that at that time, advertisements frequently represented depression-related meanings, such as unemployment and bank loans. Skill gaming ads were often represented by sports expertise – late 90’s, their number started sky rocketing, and continued increasing until 2006 (when this study ended). One may conclude that sport betting draws its meanings from the relevant consumer culture, and from the rules and features of the betted sport.