Nuestros investigadores

Maykel Alonso Arce

Publicaciones científicas más recientes (desde 2010)

Autores: Añorga, Javier, (Autor de correspondencia); Arrizabalaga, Saioa; Sedano, Beatriz; et al.
ISSN 1380-7501  Vol. 77  Nº 7  2018  págs. 7977 - 8000
The popular Internet service, YouTube, has adopted by default the HyperText Markup Language version 5 (HTML5). With this adoption, YouTube has moved to Dynamic Adaptive Streaming over HTTP (DASH) as Adaptive BitRate (ABR) video streaming technology. Furthermore, rate adaptation in DASH is solely receiver-driven. This issue motivates this work to make a deep analysis of YouTube's particular DASH implementation. Firstly, this article provides a state of the art about DASH and adaptive streaming technology, and also YouTube traffic characterization related work. Secondly, this paper describes a new methodology and test-bed for YouTube's DASH implementation traffic characterization and performance measurement. This methodology and test-bed do not make use of proxies and, moreover, they are able to cope with YouTube traffic redirections. Finally, a set of experimental results are provided, involving a dataset of 310 YouTube's videos. The depicted results show a YouTube's traffic pattern characterization and a discussion about allowed download bandwidth, YouTube's consumed bitrate and quality of the video. Moreover, the obtained results are cross-validated with the analysis of HTTP requests performed by YouTube's video player. The outcomes of this article are applicable in the field of Quality of Service (QoS) and Quality of Experience (QoE) management. This is valuable information for Internet Service Providers (ISPs), because QoS management based on assured download bandwidth can be used in order to provide a target end-user's QoE when YouTube service is being consumed.
Autores: Alonso-Arce, Maykel; Bustamante, Paul; Schmidt, C.; et al.
Revista: IRBM
ISSN 1959-0318  Vol. 35  Nº 6  2014  págs. 362 - 369
New advances in biosensor and electronic technologies will merge in new health assistance paradigms strongly based on the remote biomonitoring. Biomedical circuit and systems have much to say on this, as for example the Central Venous Catheters (CVC). Central venous catheters are commonly used in clinical practice to improve a patient's quality of life. Nevertheless, there remains a large risk of infection associated with microbial biofilm (about 80% of all human bacterial infections). The standardization bodies, the radiofrequency devices and the biosensor technology are taking their positions, and the integration of all that effort is the work proposed in this paper. An ultra-low power active medical implant is presented for in-body monitoring of Electrical BioImpedance (EBI) based sensors with a new 3-D antenna. Transmission test and detailed evaluation have been done based on two typical monitoring parameters: the frequency of the internal sensor measuring and the frequency of external communication requests. The results show up to 20 months lifetime powered with a 50 mA coin-cell battery. (C) 2014 Elsevier Masson SAS. All rights reserved.
Autores: Paredes, J; Alonso-Arce, Maykel; Schmidt, C.; et al.
ISSN 1387-2176  Vol. 16  Nº 3  2014  págs. 365 - 374
Central venous catheters (CVC) are commonly used in clinical practice to improve a patient's quality of life. Unfortunately, there is an intrinsic risk of acquiring an infection related to microbial biofilm formation inside the catheter lumen. It has been estimated that 80 % of all human bacterial infections are biofilm-associated. Additionally, 50 % of all nosocomial infections are associated with indwelling devices. Bloodstream infections account for 30-40 % of all cases of severe sepsis and septic shock, and are major causes of morbidity and mortality. Diagnosis of bloodstream infections must be performed promptly so that adequate antimicrobial therapy can be started and patient outcome improved. An ideal diagnostic technology would identify the infecting organism(s) in a timely manner, so that appropriate pathogen-driven therapy could begin promptly. Unfortunately, despite the essential information it provides, blood culture, the gold standard, largely fails in this purpose because time is lost waiting for bacterial or fungal growth. This work presents a new design of a venous access port that allows the monitoring of the inner reservoir surface by means of an impedimetric biosensor. An ad-hoc electronic system was designed to manage the sensor and to allow communication with the external receiver. Historic data recorded and stored in the device was used as the reference value for the detection of bacterial biofilm. The RF communication system sends an alarm signal to the external receiver when a microbial colonization of the port occurs. The successful in vitro analysis of the biosensor, the electronics and the antenna of the new indwelling device prototype are shown. The experimental conditions were selected in each case as the closest to the clinical working conditions for the smart central venous catheter (SCVC) testing. The results of this work allow a new generation of this kind of device that could potentially provide more efficient treatments for catheter-related infections.