944 resultados para Redes ad hoc móveis
Resumo:
La tesi sviluppa, attraverso un processo definito e gestito, una libreria Android che permette di far comunicare diversi dispositivi mobili tramite Bluetooth. Inoltre gestisce: • le richieste di connessione sia che esse provengano dall’esterno, sia che partano dal dispositivo stesso; • la dinamicità del sistema utilizzando dispositivi mobili, cioè capaci di muoversi in diverse direzioni costantemente. In tal senso, la lista dei dispositivi vicini è costantemente aggiornata. • la comunicazione in stile Peer-to-Peer(P2P). In questo caso si viene a formare un gap in quanto la libreria Android di Bluetooth usa lo stile Master-Slave per i suoi dispositivi. Per colmare questo gap, la libreria sviluppata crea un layer soprastante la libreria Bluetooth di Android e maschera lo stile di comunicazione di quest’ultima a favo- re di una comunicazione paritaria, nella quale un dispositivo può sia accettare le richieste di connessione, sia connettersi ad altri dispositivi.
Resumo:
In dieser Masterarbeit wird ein, aus einer Interaktion bzw. einem gedolmetschten medizinischen Aufklärungsgespräch bestehendes Korpus mithilfe der Instrumente und der methodischen Vorgehensweise der Konversationsanalyse untersucht. Die Gesprächspartner sind ein privater Arzt, eine Patientin und ihre, als Dolmetscherin fungierende Tochter. Die Untersuchung des Gesprächsverhaltens der Ad-hoc-Dolmetscherin durch die Anwendung der participation framework Theorie dient zur Festlegung der folgenden, nicht a priori festgelegten Verhaltensmuster: Die Dolmetscherin nimmt de facto im Gespräch eine invasive Rolle ein, die auf die Umstände ihrer Zweisprachigkeit und ihres Verwandtheitsgrades zur Patientin zurückzuführen ist. Die Tochter der Patientin – eine ausgebildete Krankenpflegerin – agiert als Laiengesprächsdolmetscherin, da sie zu einem früheren Zeitpunkt als ihre Mutter ins Gastland ausgewandert ist und die Landessprache bereits gemeistert hat. Es wird also erstmals das Bild der medizinisch ausgebildeten dolmetschenden Tochter geprägt, die die markante Tendenz aufweist, eine Advocate- und Proxyrolle einzunehmen, welche konversational als nicht neutral eingestuft wird. Dies scheint trotzdem die Qualität des gedolmetschten Textes nicht zu beeinträchtigen, da die Kommunikation zumeist reibungslos verläuft, obwohl die widergegebenen Inhalte sichtlich manipuliert werden. Aus der Analyse der gewählten Gesprächssituation lässt sich schließen, dass diese Ad-Hoc Dolmetscherin, die – im Fall des behandelten Gesprächs aus beruflichen Gründen – im behandelten medizinischen Fachbereich ausreichendes Hintergrundwissen aufweist, verglichen mit jenen Ad-Hoc Dolmetschern, die nicht über dieses Wissen verfügen, trotz stellenweiser fehlerhafter Dolmetschung und Abänderung der gesprochenen Inhalte kaum Missverständnisse aufwirft und so einen vergleichsweise ungestörten Gesprächsfluss ermöglicht.
Resumo:
OBJECTIVE: To determine the prevalence and independent predictors of significant atherosclerotic renal artery stenosis (RAS) in unselected hypertensive patients undergoing coronary angiography and to assess the 6-month outcome of those patients with a significant RAS. METHODS: One thousand, four hundred and three consecutive hypertensive patients undergoing drive-by renal arteriography were analyzed retrospectively. Univariate and multivariate logistic regression analyses were performed to identify independent predictors of RAS. In patients with significant RAS (>or=50% luminal narrowing), 6-month follow-up was assessed and outcome was compared between patients with or without renal revascularization. RESULTS: The prevalence of significant RAS was 8%. After multivariate analysis, coronary [odds ratio 5.3; 95% confidence interval (CI) 2.7-10.3; P < 0.0001], peripheral (odds ratio 3.3; 95% CI 2.0-5.5; P < 0.0001), and cerebral artery (odds ratio 2.8; 95% CI 1.5-5.3; P = 0.001) diseases, and impaired renal function (odds ratio 2.9; 95% CI 1.8-4.5; P < 0.0001) were found as independent predictors. At least one of these predictors was present in 96% of patients with RAS. In 74 patients (66%) with significant RAS, an ad hoc revascularization was performed. At follow-up, creatinine clearance was significantly higher in revascularized than in nonrevascularized patients (69.2 vs. 55.5 ml/min per 1.73 m, P = 0.029). By contrast, blood pressure was comparable between both groups, but nonrevascularized patients were taking significantly more antihypertensive drugs as compared with baseline (2.7 vs. 2.1, follow-up vs. baseline; P = 0.0066). CONCLUSION: The prevalence of atherosclerotic RAS in unselected hypertensive patients undergoing coronary angiography was low. Coronary, peripheral, and cerebral artery diseases, and impaired renal function were independent predictors of RAS. Ad hoc renal revascularization was associated with better renal function and fewer intake of antihypertensive drugs at follow-up.
Resumo:
This article describes the Mobile Ad Hoc Networking Interoperability and Cooperation (MANIAC) Challenge, a competition in MANETs. The primary objective of the competition was to assess the trade-offs between network-wide connectivity and resource utilization in a MANET comprising autonomous self-interested nodes. The competition attracted participants from academic institutions in the United States, Europe, and Africa. The data collected provide a better understanding of link stability, route effectiveness, cooperation, and competition in an autonomously deployed MANET.
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The American Psychological Association Board of Directors established an ad hoc task force on psychopharmacology to explore the desirability and feasibility of psychopharmacology prescription privileges for psychologists. In this context, the Task Force's charges were to determine the competence criteria necessary for training psychologists to provide service to patients receiving medications and to develop and evaluate the necessary curricular models. This article summarizes the Task Force's major recommendations and provides specific information regarding its training recommendations . It is hoped that this article will encourage broad discussion of psychology's most appropriate integration of psychopharmacology knowledge and its applications into its training programs and professional activities.
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A large number of proposals for estimating the bivariate survival function under random censoring has been made. In this paper we discuss nonparametric maximum likelihood estimation and the bivariate Kaplan-Meier estimator of Dabrowska. We show how these estimators are computed, present their intuitive background and compare their practical performance under different levels of dependence and censoring, based on extensive simulation results, which leads to a practical advise.
Resumo:
Target localization has a wide range of military and civilian applications in wireless mobile networks. Examples include battle-field surveillance, emergency 911 (E911), traffc alert, habitat monitoring, resource allocation, routing, and disaster mitigation. Basic localization techniques include time-of-arrival (TOA), direction-of-arrival (DOA) and received-signal strength (RSS) estimation. Techniques that are proposed based on TOA and DOA are very sensitive to the availability of Line-of-sight (LOS) which is the direct path between the transmitter and the receiver. If LOS is not available, TOA and DOA estimation errors create a large localization error. In order to reduce NLOS localization error, NLOS identifcation, mitigation, and localization techniques have been proposed. This research investigates NLOS identifcation for multiple antennas radio systems. The techniques proposed in the literature mainly use one antenna element to enable NLOS identifcation. When a single antenna is utilized, limited features of the wireless channel can be exploited to identify NLOS situations. However, in DOA-based wireless localization systems, multiple antenna elements are available. In addition, multiple antenna technology has been adopted in many widely used wireless systems such as wireless LAN 802.11n and WiMAX 802.16e which are good candidates for localization based services. In this work, the potential of spatial channel information for high performance NLOS identifcation is investigated. Considering narrowband multiple antenna wireless systems, two xvNLOS identifcation techniques are proposed. Here, the implementation of spatial correlation of channel coeffcients across antenna elements as a metric for NLOS identifcation is proposed. In order to obtain the spatial correlation, a new multi-input multi-output (MIMO) channel model based on rough surface theory is proposed. This model can be used to compute the spatial correlation between the antenna pair separated by any distance. In addition, a new NLOS identifcation technique that exploits the statistics of phase difference across two antenna elements is proposed. This technique assumes the phases received across two antenna elements are uncorrelated. This assumption is validated based on the well-known circular and elliptic scattering models. Next, it is proved that the channel Rician K-factor is a function of the phase difference variance. Exploiting Rician K-factor, techniques to identify NLOS scenarios are proposed. Considering wideband multiple antenna wireless systems which use MIMO-orthogonal frequency division multiplexing (OFDM) signaling, space-time-frequency channel correlation is exploited to attain NLOS identifcation in time-varying, frequency-selective and spaceselective radio channels. Novel NLOS identi?cation measures based on space, time and frequency channel correlation are proposed and their performances are evaluated. These measures represent a better NLOS identifcation performance compared to those that only use space, time or frequency.