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Search Results: 1 - 10 of 3844 matches for " Susana Sargento "
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Social-aware Opportunistic Routing Protocol based on User's Interactions and Interests
Waldir Moreira,Paulo Mendes,Susana Sargento
Computer Science , 2014, DOI: 10.1007/978-3-319-04105-6_7
Abstract: Nowadays, routing proposals must deal with a panoply of heterogeneous devices, intermittent connectivity, and the users' constant need for communication, even in rather challenging networking scenarios. Thus, we propose a Social-aware Content-based Opportunistic Routing Protocol, SCORP, that considers the users' social interaction and their interests to improve data delivery in urban, dense scenarios. Through simulations, using synthetic mobility and human traces scenarios, we compare the performance of our solution against other two social-aware solutions, dLife and Bubble Rap, and the social-oblivious Spray and Wait, in order to show that the combination of social awareness and content knowledge can be beneficial when disseminating data in challenging networks.
Opportunistic Routing Based on Daily Routines
Waldir Moreira,Paulo Mendes,Susana Sargento
Computer Science , 2014, DOI: 10.1109/WoWMoM.2012.6263749
Abstract: Opportunistic routing is being investigated to enable the proliferation of low-cost wireless applications. A recent trend is looking at social structures, inferred from the social nature of human mobility, to bring messages close to a destination. To have a better picture of social structures, social-based opportunistic routing solutions should consider the dynamism of users' behavior resulting from their daily routines. We address this challenge by presenting dLife, a routing algorithm able to capture the dynamics of the network represented by time-evolving social ties between pair of nodes. Experimental results based on synthetic mobility models and real human traces show that dLife has better delivery probability, latency, and cost than proposals based on social structures.
Assessment Model for Opportunistic Routing (LatinCom)
Waldir Moreira,Paulo Mendes,Susana Sargento
Computer Science , 2014, DOI: 10.1109/LatinCOM.2011.6107393
Abstract: Due to the increased capabilities of mobile devices and through wireless opportunistic contacts, users can experience new ways to share and retrieve content anywhere and anytime, even in the presence of link intermittency. Due to the significant number of available routing solutions, it is difficult to understand which one has the best performance, since all of them follow a different evaluation method. This paper proposes an assessment model, based on a new taxonomy, which comprises an evaluation guideline with performance metrics and experimental setup to aid designers in evaluating solutions through fair comparisons. Simulation results based on the proposed model revisit the performance results published by Epidemic, PROPHET, and Bubble Rap, showing how they perform under the same set of metrics and scenario.
Assessment Model for Opportunistic Routing
Waldir Moreira,Paulo Mendes,Susana Sargento
Computer Science , 2014,
Abstract: This paper proposes an assessment model, based on a new taxonomy, which comprises an evaluation guideline with performance metrics and experimental setup to aid designers in evaluating solutions through fair comparisons. Simulation results are provided based on the proposed model considering Epidemic, PROPHET, Bubble Rap, and Spray and Wait, and showing how they perform under the same set of metrics and scenario
Experimental Evaluation of the Usage of Ad Hoc Networks as Stubs for Multiservice Networks
Miguel Almeida,Rafael Sarr?,Jo?o Paulo Barraca,Susana Sargento
EURASIP Journal on Wireless Communications and Networking , 2007, DOI: 10.1155/2007/62967
Abstract: This paper describes an experimental evaluation of a multiservice ad hoc network, aimed to be interconnected with an infrastructure, operator-managed network. This network supports the efficient delivery of services, unicast and multicast, legacy and multimedia, to users connected in the ad hoc network. It contains the following functionalities: routing and delivery of unicast and multicast services; distributed QoS mechanisms to support service differentiation and resource control responsive to node mobility; security, charging, and rewarding mechanisms to ensure the correct behaviour of the users in the ad hoc network. This paper experimentally evaluates the performance of multiple mechanisms, and the influence and performance penalty introduced in the network, with the incremental inclusion of new functionalities. The performance results obtained in the different real scenarios may question the real usage of ad-hoc networks for more than a minimal number of hops with such a large number of functionalities deployed.
Experimental Evaluation of the Usage of Ad Hoc Networks as Stubs for Multiservice Networks
Almeida Miguel,Sarr? Rafael,Barraca Jo?oPaulo,Sargento Susana
EURASIP Journal on Wireless Communications and Networking , 2007,
Abstract: This paper describes an experimental evaluation of a multiservice ad hoc network, aimed to be interconnected with an infrastructure, operator-managed network. This network supports the efficient delivery of services, unicast and multicast, legacy and multimedia, to users connected in the ad hoc network. It contains the following functionalities: routing and delivery of unicast and multicast services; distributed QoS mechanisms to support service differentiation and resource control responsive to node mobility; security, charging, and rewarding mechanisms to ensure the correct behaviour of the users in the ad hoc network. This paper experimentally evaluates the performance of multiple mechanisms, and the influence and performance penalty introduced in the network, with the incremental inclusion of new functionalities. The performance results obtained in the different real scenarios may question the real usage of ad-hoc networks for more than a minimal number of hops with such a large number of functionalities deployed.
Improving VANET Protocols via Network Science
Romeu Monteiro,Susana Sargento,Wantanee Viriyasitavat,Ozan K. Tonguz
Computer Science , 2013,
Abstract: Developing routing protocols for Vehicular Ad Hoc Networks (VANETs) is a significant challenge in these large, self- organized and distributed networks. We address this challenge by studying VANETs from a network science perspective to develop solutions that act locally but influence the network performance globally. More specifically, we look at snapshots from highway and urban VANETs of different sizes and vehicle densities, and study parameters such as the node degree distribution, the clustering coefficient and the average shortest path length, in order to better understand the networks' structure and compare it to structures commonly found in large real world networks such as small-world and scale-free networks. We then show how to use this information to improve existing VANET protocols. As an illustrative example, it is shown that, by adding new mechanisms that make use of this information, the overhead of the urban vehicular broadcasting (UV-CAST) protocol can be reduced substantially with no significant performance degradation.
HarborNet: A Real-World Testbed for Vehicular Networks
Carlos Ameixieira,André Cardote,Filipe Neves,Rui Meireles,Susana Sargento,Luís Coelho,Jo?o Afonso,Bruno Areias,Eduardo Mota,Rui Costa,Ricardo Matos,Jo?o Barros
Computer Science , 2013,
Abstract: We present a real-world testbed for research and development in vehicular networking that has been deployed successfully in the sea port of Leix\~oes in Portugal. The testbed allows for cloud-based code deployment, remote network control and distributed data collection from moving container trucks, cranes, tow boats, patrol vessels and roadside units, thereby enabling a wide range of experiments and performance analyses. After describing the testbed architecture and its various modes of operation, we give concrete examples of its use and offer insights on how to build effective testbeds for wireless networking with moving vehicles.
A Rare Case of Diaphragmatic Mass: The Key to Diagnosis of a Lung Adenocarcinoma  [PDF]
Cláudia Rocha, Vera Clérigo, Lígia Fernandes, André Rodrigues, Dora Sargento, Glória Silva
Advances in Lung Cancer (ALC) , 2014, DOI: 10.4236/alc.2014.33009
Abstract: Lung cancer is a leading cause of death due to malignancy worldwide. Diaphragmatic metastasis secondary to primary lung cancer is rare. In the literature, only a few cases have been described as the majority of cases of diaphragmatic metastasis which are secondary to gastrointestinal neoplasia. The authors report a rare case of diaphragmmatic metastasis from a primary adenocarcinoma of the lung in a 76-year-old female patient with no history of active or passive smoking with progressive worsening fatigue, asthenia, malaise, and unquantified weight loss with three months of evolution, associated with pleuritic chest pain and edema of the lower limbs for fifteen days previous to hospital admission. Chest X-ray showed elevation of the right hemi-diaphragm and thoracic-abdominal-pelvic computed tomography revealed a complex multilobuled mass with neoformative characteristics intersecting the diaphragm and invading the dome liver and the right lung region. Biopsy of the mass was performed whose histological examination was consistent with moderately differentiated adenocarcinoma. Immunohistochemical examination was positive for cytokeratin 7 and negative forcytokeratin 20, suggesting primary lung tumor. A positron emission tomography was performed without uptake in other locations. Diagnosis of adenocarcinoma with diaphragmatic metastasis was then admitted and the patient started chemotherapy with carboplatin and gemcitabine. The patient died six months after the diagnosis. The authors also present a brief theoretical discussion based on the current and scarce literature on this rare entity.
Infective Endocarditis with Negative Cultures: A Defiant Diagnosis  [PDF]
Cláudia Rocha, Vera Clérigo, Lígia Fernandes, André Rodrigues, Dora Sargento, Glória Silva
Case Reports in Clinical Medicine (CRCM) , 2014, DOI: 10.4236/crcm.2014.38101
Abstract:

The diagnosis and management of blood culture-negative endocarditis constitute a real clinical challenge and a systemic approach is necessary for a successful outcome. The authors report a case of a female patient aged 26, with previous clinical history of valve disease and heart failure NYHA class II, with decompensation of co-morbidities associated with fever, productive cough, nonselective anorexia and unquantified weight loss with one month of evolution with negative blood cultures. Transesophageal echocardiography revealed the presence of severe pulmonary hypertension and mitral valve vegetations in the context of positive serology for Q fever. Herein, the authors report a case of blood culture-negative endocarditis and present a brief review on the management of this medical condition. We highlighted the diagnostic difficulties of blood culture-negative endocarditis and subacute clinical presentation, which sometimes present with fever of unknown origin and complaints of deterioration of cardiac function, thus creating a challenging differential diagnosis.

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