Electronic and photonic switching in the atm era

Broadband networks require high-capacity switches in order to properly manage large amounts of traffic fluxes. Electronic and photonic technologies are being used to achieve this objective both allowing different multiplexing and switching techniques. Focusing on the asynchronous transfer mode (ATM), the inherent different characteristics of electronics and photonics makes different architectures feasible. In this paper, different switching structures are described, several ATM switching architectures which have been recently implemented are presented and the implementation characteristics discussed. Three diverse points of view are given from the electronic research, the photonic research and the commercial switches. Although all the architectures where successfully tested, they should also follow different market requirements in order to be commercialised. The characteristics are presented and the architectures projected over them to evaluate their commercial capabilities.Peer ReviewedPostprint (published version

Re-estructuración de los sistemas metropolitanos hacia modelos policéntricos?: bipolaridad o sistema policéntrico equipotencial: un análisis para la Región Metropolitana de Barcelona

Esta comunicación forma parte del trabajo de investigación pre-doctoral realizado, cuyo objetivo era poner las bases para la actual investigación doctoral. Dicha investigación realizada se resume en: el funcionamiento actual de los sistemes urbanos en los últimos decenios se ha ido alejando de forma progresiva de la estructura urbana monocéntrica desarrollada a partir de los trabajos de Von Thünen , Christaller, Alonso, Mills y Muth entre otros, hacia un nuevo paradigma de estructura urbana basado en una progresiva aparición y consolidación de sistemas complejos, en parte dispersos y en parte policéntricos; donde este último, el policéntrico, se ha ido erigiendo como el modelo urbano más deseado en la medida que se propugna como objetivo normativo por la Pespectiva de Desarrollo Espacial Europea por ser considerado como el modelo de estructura urbana que afavorece más claramente el refuerzo de la competividad y de la cohesión territorial, es decir sistemas metropolitanos más eficientes y sostenibles.Peer Reviewe

Noninvasive ventilation in acute respiratory failure

After the institution of positive-pressure ventilation, the use of noninvasive ventilation (NIV) through an interface substantially increased. The first technique was continuous positive airway pressure; but, after the introduction of pressure support ventilation at the end of the 20th century, this became the main modality. Both techniques, and some others that have been recently introduced and which integrate some technological innovations, have extensively demonstrated a faster improvement of acute respiratory failure in different patient populations, avoiding endotracheal intubation and facilitating the release of conventional invasive mechanical ventilation. In acute settings, NIV is currently the first-line treatment for moderate-to-severe chronic obstructive pulmonary disease exacerbation as well as for acute cardiogenic pulmonary edema and should be considered in immunocompromised patients with acute respiratory insufficiency, in difficult weaning, and in the prevention of postextubation failure. Alternatively, it can also be used in the postoperative period and in cases of pneumonia and asthma or as a palliative treatment. NIV is currently used in a wide range of acute settings, such as critical care and emergency departments, hospital wards, palliative or pediatric units, and in pre-hospital care. It is also used as a home care therapy in patients with chronic pulmonary or sleep disorders. The appropriate selection of patients and the adaptation to the technique are the keys to success. This review essentially analyzes the evidence of benefits of NIV in different populations with acute respiratory failure and describes the main modalities, new devices, and some practical aspects of the use of this technique

La «digitalització» de l’altre

Mai abans en la Història l’individu havia disposat de tants artefactes tecnològics per dir a través de les paraules, de les imatges, dels sons. Si en l’ADN de la democràcia està inscrit el concepte d’àgora com a la necessitat de compartir informacions i experiències, les tecnologies de la comunicació culminen el somni de qualsevol intel·lectual il·lustrat