Papers by Pablo Rodriguez
Analysis of the Diierent Caching Systems for the Web
The increasing demand in use of the World Wide Web in combination of the ease with which large vi... more The increasing demand in use of the World Wide Web in combination of the ease with which large video and audio data types can be incorporated, create great demand on bandwidth through the Inter-net. Therefore there is a need for more eecient mechanisms to reduce the latency, bandwidth and servers load. Document caching can improve this performance by exploiting the geographic and temporal locality of reference properties exhibited in client access patterns. We present a review of the diierent caching schemes and propose a new way to treat very popular and frequently changed WWW pages. We believe that this could be implemented using a reliable multicast transport protocol where information would be continuously multicasted from servers towards clients downstream.
En este trabajo presentamos algunas reflexiones sobre los aprendizajes realizados por los autores... more En este trabajo presentamos algunas reflexiones sobre los aprendizajes realizados por los autores como catedra tras veinte anos de experiencia ensenando metodos y tecnicas de investigacion a alumnos del ultimo ano de la carrera de antropologia con orientacion sociocultural en la Facultad de Ciencias Naturales y Museo de la U.N.L.P. Parte de estas reflexiones derivan de un analisis de las expectativas manifestadas por los alumnos con respecto a la materia al inicio de la cursada en los ultimos anos.
Ventilación Mecánica Asistida: Hacia una mejor adaptación del respirador a las necesidades del paciente
La Ventilación Mecánica es rutinariamente aplicada a los pacientes internados en las Unidades de ... more La Ventilación Mecánica es rutinariamente aplicada a los pacientes internados en las Unidades de Cuidados Intensivos con la finalidad de reducir el trabajo de la respiración, mejorar la oxigenación o corregir acidosis respiratoria. Aunque con los modos tradicionales de Ventilación Mecánica se alcanzan muchos de estos objetivos, ellos tienen importantes limitaciones. Los modos alternativos podr'ian superar alguna de estas limitaciones y ahora están disponibles en los respiradores más modernos. En este art'iculo revisaremos aspectos generales del funcionamiento y las limitaciones de los modos de Ventilación Mecánica asistida tradicionales y el potencial interés de algunos nuevos modos promisorios.
Real Effectiveness of Anti-drug Campaigns. An Exploratory Analysis in the Young Spanish People
Models as the Protection Motivation Theory (PMT) aim to understand those data and variables consi... more Models as the Protection Motivation Theory (PMT) aim to understand those data and variables considered by individuals when facing the challenge of a behavioural change, as well as the more or less important they are. It is a key issue for social marketing responsibles, as they need a better understanding of the reasons for compliance or not with a suggested
2010 IEEE International Conference on Communications, 2010
In wireless multihop networks, techniques such as multipath, local retransmissions and network co... more In wireless multihop networks, techniques such as multipath, local retransmissions and network coding have been successfully used to increase throughput and reduce losses. However, while these techniques improve forwarding performance for UDP, they often introduce side effects such as packet reordering and delay that heavily affect TCP traffic. In this paper we introduce CoMP, a network coding multipath forwarding scheme that improves the reliability and the performance of TCP sessions in wireless mesh networks. CoMP exploits the wireless mesh path diversity using network coding, performs congestion control and uses a credit-based method to control the rate at which linear combinations are transmitted. CoMP uses a simple algorithm to estimate losses and to send redundant linear combinations in order to maintain the decoding delay at a minimum and to prevent TCP timeouts and retransmissions. We evaluate CoMP through extensive simulations and compare it to state-of-the-art protocols. We show that CoMP not only achieves a higher throughput, but also is more efficient than existing protocols, making TCP sessions feasible for wireless mesh networks even under heavy losses.
Revista Española de Cardiologia, 2004
Proceedings of the 6th ACM SIGCOMM on Internet measurement - IMC '06, 2006
In this paper we present the first implementation of a P2P content distribution system that uses ... more In this paper we present the first implementation of a P2P content distribution system that uses Network Coding. Using results from live trials with several hundred nodes, we provide a detailed performance analysis of such P2P system. In contrast to prior work, which mainly relies on monitoring P2P systems at particular locations, we are able to provide performance results from a variety of novel angles by monitoring all components in the P2P distribution. In particular, we show that Network Coding is practical in a P2P setting since it incurs little overhead, both in terms of CPU processing and I/O activity, and it results in smooth, fast downloads, and efficient server utilization. We also study the importance of topology construction algorithms in real scenarios and study the effect of peers behind NATs and firewalls, showing that the system is surprisingly robust to large number of unreachable peers. Finally, we present performance results related to verifying network encoded blocks on-the-fly using special security primitives called Secure-Random-Checksums.
Revista Española de Patología, 2008
The new WHO classification of soft tissue tumours, has introduced some changes in the nomenclatur... more The new WHO classification of soft tissue tumours, has introduced some changes in the nomenclatura of pericytic lesions but also in its clinicopathologic definition. Among this kind of lesions, sinonasal-type hemangiopericytoma is considered a tumor with true pericytic differentiation. It is a upper aero-digestive tract neoplasm, slightly commoner in women than men, and occurs in all age groups but it is more commonly seen in the 6th and 7th decades of life. The most frequent clinical presentation is airway obstruction and/or epistaxis and there are no known etiologic factors linked with its development. In general, sinonasal-type hemangiopericytoma is an indolent tumor and local recurrence results from inadequate surgical excision. Tumors with an aggressive behaviour, locally destructive or metastatic, have been occasionally reported in the literature. We describe a case of this uncommon tumor with the characteristics clinical and pathologic findings in this lesion. A 85-year-old woman presented with a 2-year history of epistaxis. The tumor involved the left nasal cavity and also the homolateral paranasal sinuses, it was polypoid and the patient was treated by endonasal endoscopic surgery with a complete resection. Microscopically, it was constituted from sheets of uniform cells with a ovoid nuclei and indistinct cytoplasm distributed around characteristic hyalinized vascular spaces. Nuclear pleomorphism was absent and mitotic figures were identified a very low rate. The tumor was immunoreactive with vimentin, muscle specific actin, smooth muscle actin and CD34. After two-years of follow-up, the patient is alive and without evidence of disease.
Reducing channel change delay in IPTV by predictive pre-joining of TV channels
Signal Processing: Image Communication, 2011
ABSTRACT One of the major concerns of IPTV network deployment is channel change delay (also known... more ABSTRACT One of the major concerns of IPTV network deployment is channel change delay (also known as zapping delay). This delay can add up to 2s or more, and its main culprits are synchronisation and buffering of the media streams. Proving the importance of the problem is the already significant amount of literature addressing it. We start this paper with a survey of techniques proposed to reduce IPTV channel change delay.Then, by analysing an extensive dataset from an operational IPTV provider – comprising 255 thousand users, 150 TV channels, and covering a 6-month period – we have observed that most channel switching events are relatively predictable: users very frequently switch linearly, up or down to the next TV channel. This fact motivated us to use this dataset to analyse in detail a specific type of solutions to this problem, namely, predictive pre-joining of TV channels. In these schemes each set top box (STB) simultaneously joins additional multicast groups (TV channels) along with the one that is requested by the user. If the user switches to any of these channels the switching latency is virtually eliminated, not affecting therefore user's experience.We start by evaluating a simple scheme, where the neighbouring channels (i.e., channels adjacent to the requested one) are pre-joined by the STB during zapping periods. Notwithstanding the simplicity of this scheme, trace-driven simulations show that the zapping delay can be virtually eliminated for a significant percentage of channel switching requests. For example, when sending the previous and the next channel concurrently with the requested one, for only 1min after a zapping event, switching delay is eliminated for close to half of all channel switching requests. Importantly, this result is achieved with a negligible increase of bandwidth utilisation in the access link. Other more complex schemes where user behaviour is tracked were also evaluated, but the improvement over the simple scheme was insignificant.
Does Enterpreneurship Contribute to the Marketing of University Curric ula?
Academic Public …, 2010
Downloadable! Aiming justificative arguments to include entrepreneurship as a part of university ... more Downloadable! Aiming justificative arguments to include entrepreneurship as a part of university curricula, some results show in a comparison between two representative samples of students in their first and last academic year at the university. First, we assess respondents' perceptions ...
Intensive care …, 2006
Intensive Care Med (2006) 32:15151522 DOI 10.1007/s00134-006-0301-8 ORIGINAL ... Arnaud W. Thill... more Intensive Care Med (2006) 32:15151522 DOI 10.1007/s00134-006-0301-8 ORIGINAL ... Arnaud W. Thille Pablo Rodriguez Belen Cabello François Lellouche Laurent Brochard ... Received: 17 February 2006 Accepted: 29 June 2006 Published online: 1 August 2006 © ...
American journal of …, 2006
Rationale and objectives: Duration of weaning from mechanical ventilation may be reduced by the u... more Rationale and objectives: Duration of weaning from mechanical ventilation may be reduced by the use of a systematic approach. We assessed whether a closed-loop knowledge-based algorithm introduced in a ventilator to act as a computer-driven weaning protocol can improve patient outcomes as compared to usual care. Methods and measurements: We conducted a multicenter randomized controlled study with concealed allocation to compare usual care for weaning to computer-driven weaning. The computerized protocol included an automatic gradual reduction in pressure support, automatic performance of spontaneous breathing trials (SBT), and generation of an incentive message when a SBT was successfully passed. One hundred forty-four patients were enrolled before weaning initiation. They were randomly allocated to computer-driven weaning or to physician-controlled weaning according to local guidelines. Weaning duration until successful extubation and total duration of ventilation were the primary endpoints. Main results: Weaning duration was reduced in the computer-driven group from a median of 5 to 3 days (P=0.01) and total duration of mechanical ventilation from 12 to 7.5 days (P=0.003). Reintubation rate did not differ (23 vs 16 %, P=0.40). Computer-driven weaning also decreased median intensive-care-unit stay duration from 15.5 to 12 days (P=0.02) and caused no adverse events. The amount of sedation did not differ between groups. In the usual care group compliance to recommended modes and to SBT was estimated respectively at 96% and 51%. Conclusions: The specific computer-driven system used in this study can reduce mechanical ventilation duration and intensive-care-unit length of stay, as compared to physician-controlled weaning process.
Proceedings of the …, 2004
MAR: A Commuter Router Infrastructure for the Mobile Internet Pablo Rodriguez Microsoft Research ... more MAR: A Commuter Router Infrastructure for the Mobile Internet Pablo Rodriguez Microsoft Research 7 JJ Thomson Avenue Cambridge, UK [email protected] Rajiv Chakravorty University of Cambridge Computer Laboratory Cambridge, UK [email protected] ...
IEEE/ACM Transactions on Networking …, 2002
AbstractPopular content is frequently replicated in multiple servers or caches in the Internet t... more AbstractPopular content is frequently replicated in multiple servers or caches in the Internet to offload origin servers and improve end-user experience. However, choosing the best server is a nontrivial task and a bad choice may provide poor end user experience. In contrast to ...
Proceedings of the 7th …, 2007
User Generated Content (UGC) is re-shaping the way people watch video and TV, with millions of vi... more User Generated Content (UGC) is re-shaping the way people watch video and TV, with millions of video producers and consumers. In particular, UGC sites are creating new view-ing patterns and social interactions, empowering users to be more creative, and developing new ...
… of the 5th International Workshop on …, 2006
In this paper we present our experiences with a P2P content dis-tribution system that uses Networ... more In this paper we present our experiences with a P2P content dis-tribution system that uses Network Coding. Using results from live trials, we are able to present a detailed performance analysis of such P2P system from a variety of novel perspectives. We show that Network ...
Internet traffic to homes is surging, driven by the demand for rich content and the proliferation... more Internet traffic to homes is surging, driven by the demand for rich content and the proliferation of home networks. This creates a huge problem for ISPs since residential customers expect the certainty of a fixed bill while ISPs do not want to upgrade backhaul equipment frequently in the absence of extra revenue streams. We consider simple variants on existing flat-rate schemes that will enable homes to self-select a portion of their peak hours traffic and move it to nonpeak hours to benefit from offered incentives. We present a well-defined formulation of the problem and characterize its computational complexity. We show that a simple fractional algorithm achieves the optimal traffic reallocation and is realizable with small modifications to existing infrastructure. The fractional model also captures the reality that homes may be willing to move a fraction of their delay-tolerant traffic in response to appropriate incentives. Using trace-driven simulations based on well-accepted utility models and actual backbone traffic from a large ISP, we demonstrate that our incentive scheme can substantially lower peak congestion while still satisfying the increased demand of home networks.
This article is an editorial note submitted to CCR. It has NOT been peer reviewed. The authors ta... more This article is an editorial note submitted to CCR. It has NOT been peer reviewed. The authors take full responsibility for this article's technical content. Comments can be posted through CCR Online.
Access networks include modems, home gateways, and DSL Access Multiplexers (DSLAMs), and are resp... more Access networks include modems, home gateways, and DSL Access Multiplexers (DSLAMs), and are responsible for 70-80% of total network-based energy consumption. In this paper, we take an in-depth look at the problem of greening access networks, identify root problems, and propose practical solutions for their user-and ISP-parts. On the user side, the combination of continuous light traffic and lack of alternative paths condemns gateways to being powered most of the time despite having Sleep-on-Idle (SoI) capabilities. To address this, we introduce Broadband Hitch-Hiking (BH 2), that takes advantage of the overlap of wireless networks to aggregate user traffic in as few gateways as possible. In current urban settings BH 2 can power off 65-90% of gateways. Powering off gateways permits the remaining ones to synchronize at higher speeds due to reduced crosstalk from having fewer active lines. Our tests reveal speedup up to 25%. On the ISP side, we propose introducing simple inexpensive switches at the distribution frame for batching active lines to a subset of cards letting the remaining ones sleep. Overall, our results show an 80% energy savings margin in access networks. The combination of BH 2 and switching gets close to this margin, saving 66% on average.
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Papers by Pablo Rodriguez