António Sousa

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Database replication based on group communication systems has recently been proposed as an efficient and resilient solution for large-scale data management. However, its evaluation has been conducted either on simplistic simulation models, which fail to assess concrete implementations, or on complete system implementations which are costly to test with(More)
Several techniques for database replication using group communication have recently been proposed, namely, the Database State Machine, Postgres-R, and the NODO protocol. Although all rely on a totally ordered multicast for consistency, they differ substantially on how multicast is used. This results in different performance trade-offs which are hard to(More)
Partial replication is an alluring technique to ensure the reliability of very large and geographically distributed databases while, at the same time, offering good performance. By correctly exploiting access locality most transactions become confined to a small subset of the database replicas thus reducing processing, storage access and communication(More)
This paper presents a system which extends the use of the traditional white cane by the blind for navigation purposes in indoor environments. Depth data of the scene in front of the user is acquired using the Microsoft Kinect sensor which is then mapped into a pattern representation. Using neural networks, the proposed system uses this information to(More)
Deduplication is widely accepted as an effective technique for eliminating duplicated data in backup and archival systems. Nowadays, deduplication is also becoming appealing in cloud computing, where large-scale virtual-ized storage infrastructures hold huge data volumes with a significant share of duplicated content. There have thus been several proposals(More)
This paper describes a new methodology for lane detection in Thin-Layer Chromatography images. An approach based on the continuous wavelet transform is used to enhance the relevant lane information contained in the intensity profile obtained from image data projection. Lane detection proceeds in three phases: the first obtains a set of candidate lanes,(More)
Although epidemic or gossip-based multicast is a robust and scalable approach to reliable data dissemination, its inherent redundancy results in high resource consumption on both links and nodes. This problem is aggravated in settings that have costlier or resource constrained links, as happens in Cloud Computing infrastruc-tures composed by several(More)
INTRODUCTION Severity and outcome assessments are crucial in trauma. Our aim was to describe the role of a group of cytokines (TNFα, IL-6, IL-10, and HMGB-1) and ICAM-1 as severity and outcome assessment tools and their kinetics in the first 72 h after severe trauma. MATERIALS AND METHODS Authors designed a prospective cohort study of severe polytrauma(More)