Servicios avanzados de telefonía IP mediante SIP

La telefonía IP es una evolución de la telefonía convencional, que funciona mediante conmutación de circuitos, hacia conmutación de paquetes, un tipo de conmutación, en principio no pensada para este fin y que gracias al crecimiento de la popularidad de las redes de acceso de banda ancha aparece como una realidad viable. SIP es el protocolo de señalización utilizado en este tipo de telefonía. La incorporación de servidores de aplicaciones SIP permite la implementación de servicios avanzados en el marco de la telefonía IP que incrementan las posibilidades que ofrece la telefonía convencional. Para disponer de un servidor de aplicaciones dentro de un entorno hay que definir los elementos básicos de la arquitectura a la que pertenece tales como la integración con otros servidores de aplicaciones, con servidores SIP, con puertas de enlace, etc. La interacción de todos estos elementos se muestra en la explicación de un ejemplo real.Peer Reviewe

Application layer multicast algorithm

This paper presents a multicast algorithm, called MSM-s, for point-to-multipoint transmissions. The algorithm, which has complexity O(n2) in respect of the number n of nodes, is easy to implement and can actually be applied in other point-to multipoint systems such as distributed computing. We analyze the algorithm and we provide some upper and lower bounds for the multicast time delay.Peer Reviewe

Topologías para la distribución de contenidos en redes de comunicación

The peer-to-peer (P2P) overlay networks are distribution topologies that take advantage of the ability that their nodes have to forward the information that they receive. For the particular case of video transmission using P2P networks, known as streaming P2P, there are implementations based on BitTorrent protocol data dissemination for files downloading. These networks use a pseudorandom topology which makes difficult to determine both the size of the network -defined as the maximum number of nodes which can receive information with a given quality of service- and the distribution delay. Despite this lack of definition, in the current thesis we present a structured network in which the nodes establish both incoming and outgoing connections according to a deterministic joining algorithm. That topology allows to calculate exactly the number of nodes that may join the network and that in stable conditions may get the flow with guaranteed quality of service, and also one very fitted bound for the total distribution delay. In our case, we have defined networks which contain a single source node with a bandwidth weater than the bandwidth of the information flow, and also a set of nodes with a bandwidth lower than the bandwidth of the flow. This constraint is used to distinguish the high capacity nodes from the terminal nodes which either have physical limitations due to their access link bandwidth or do not consider to allocate all their bandwidth to the forwarding of the information flow. In fact, high capacity nodes can be considered sources either because they produce the flow physically or because, receiving it from another distribution network, they forward it as source to the low bandwidth nodes that belong to the P2P network. Once the distribution topology is described, we define the mathematical model for its analysis. With this purpose, we normalize the flow bandwidth and we define a network joining algorithm with the aim of optimizing distribution delay. Following, the network topology is characterized by means of three parameters: the number of nodes that can be served directly by the source, the number of download connections that must arrive to a node to guarantee the reception at unitary rate, and the maximum number of upload connections that a node can establish. Likewise, the information flow is segmented into generic information units called objects, which are transmitted into the network by means of a certain set of dissemination trees. The number of dissemination trees corresponds to the number of download connections of a node. With this background material, we calculate the maximum number of peers which can be connected, under stable conditions, to the network, and also a very fitted bound for the transmission delay. Besides, we present a simulation that allows to evaluate the performance of the described topology in the field of VANET networks. Finally, in the last chapter we present a proposal for application-layer multicast distribution network which can be used to send the information flow from the node that initially produces it to the source nodes of the P2P distribution network that we have described.Las redes superpuestas peer-to-peer (P2P) son topologías de distribución que aprovechan la capacidad que tienen sus nodos de retransmitir a otros nodos la información que reciben. En el caso particular de la transmisión de vídeo mediante redes P2P, conocida como streaming P2P, existen implementaciones basadas en la diseminación de datos del protocolo BitTorrent de descarga de ficheros. Estas redes emplean una topología pseudoaletoria que hace difícilmente caracterizable tanto el tamaño que puede tener la red -entendido como el máximo número de nodos a los que se puede garantizar una calidad de servicio determinada- como el retardo de distribución. Frente a esta falta de definición, en el presente trabajo se presenta una red estructurada en la que los nodos establecen conexiones tanto de recepción como de retransmisión según un algoritmo de ingreso determinista. Dicha topología permite calcular exactamente el número máximo de nodos que pueden formar la red y que, en condiciones de estabilidad, reciben el flujo con garantías de calidad, así como una cota muy ajustada del retardo total de distribución. En nuestro caso, hemos definido redes formadas por un único nodo fuente con una capacidad mayor que el ancho de banda de la transmisión del flujo, así como por una serie de nodos cuya capacidad es inferior al ancho de banda de dicho flujo. Esta restricción sirve para separar los nodos de alta capacidad de los nodos terminales que o bien tienen limitaciones físicas debido a la capacidad de su enlace o bien no quieren destinar toda su capacidad a la retransmisión del flujo de información. De hecho, los nodos de alta capacidad pueden considerarse fuentes o bien porque generan físicamente el flujo o bien porque, recibiéndolo a través de otra red de distribución, lo retransmiten como fuente a los nodos de baja capacidad que conforman la red P2P. Una vez descrita la topología de distribución, se define el modelo matemático para su análisis. Para ello se normaliza el ancho de banda del flujo y se propone un algoritmo de ingreso de nodos en la red con el objeto de optimizar el retardo de distribución. A continuación, se caracteriza la topología de la red mediante tres parámetros: el número de nodos a los que puede servir el nodo fuente, el número de conexiones de descarga que deben llegar a un nodo para recibir el flujo a tasa unitaria y el número máximo de conexiones de subida que puede establecer un nodo. Asimismo, se segmenta el flujo de información en unidades genéricas, denominadas objetos, que se diseminan en la red a través de un determinado conjunto de árboles de difusión. El número de árboles de difusión se corresponde con el número de conexiones de descarga de los nodos. Todo esto permite obtener una expresión del número de nodos que, en condiciones de estabilidad, pueden conectarse a la red, así como una cota muy ajustada del retardo total de transmisión. Presentamos además una simulación que permite evaluar el rendimiento de la topología descrita en el entorno de redes VANET. De forma complementaria, en el último capítulo se presenta una propuesta de distribución multicast en la capa de aplicación que puede emplearse para transmitir el flujo de información desde el nodo que lo produce inicialmente hasta los nodos fuentes de las redes P2P de distribución.Postprint (published version

A user space implementation of the AODVv2 routing protocol

Ad hoc On Demand Distance Vector Routing (AODV) protocol is a reactive MANET routing protocol frequently used as reference for either developing new ad hoc routing protocols or performance assessment purposes. Although it is present in several general-purpose network simulators (e.g. ns2, omnetpp, etc.), there are few implementations that can be used under real conditions for on-field research or performance evaluation. This paper presents a user space implementation of the last version of this protocol, the AODVv2, that can be deployed in any device able to run the Linux O.S. The goal is developing a fresh, open source and easy-to-maintain implementation of the AODVv2 protocol that can be used by the research community for testing purposes. The paper provides a description of the main design and encoding decisions taken in order to implement the protocol, and explains the main testing actions carried out to prove its correctness.Postprint (published version

Implementation and analysis of the AODVv2 routing protocol in ARM devices

​© 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.AODVv2 is a well-known routing protocol used in MANETs (Mobile Ad hoc Networks). Formerly known as DYMO (DYnamic MANET On-demand), it is frequently used as a reference for routing protocols assessment. However, implementations of these protocols are scarce and the few ones available are currently outdated, no longer maintained and hardly upgradeable. This paper provides the details of a new AODVv2 implementation to be used in embedded devices working with the ARM microprocessor architecture. A user-space approach has been followed so both the upgradability and platformindependence are favored. A WiFi ad hoc network, modeling representative real scenarios, has been deployed to verify the correctness of the developed AODVv2 code and assess the performance of the protocol under realistic traffic conditions. A virtual machine has been used to perform a cross-compilation of a the code that implements the DYMO protocol in the Intel x86 computer architecture. Once compiled for being used in ARMbased devices, the code has been tested in Raspberry Pi devices to verify the proper behaviour. Simple scenarios and scenarios with high density of nodes have been deployed and data have been collected and analysed.Postprint (author's final draft

Implementación en el espacio de usuario del protocolo de encaminamiento AODVv2

El protocolo AODV es un protocolo reactivo de encaminamiento para redes MANET que se utiliza frecuentemente como referencia tanto para desarrollar nuevos protocolos de encaminamiento en redes ad hoc como para evaluar su rendimiento. Aunque el protocolo está presente en varios simuladores de red (por ejemplo, ns2, OMNeT++, etc.), existen pocas implementaciones que puedan emplearse en condiciones reales para la investigación de campo o de evaluación. Este documento presenta una implementación en el espacio de usuario de la última versión del protocolo, el AODVv2, que se puede utilizar en cualquier dispositivo capaz de ejecutar Linux. El objetivo del proyecto ha sido el desarrollo de una implementación de AODVv2 de codigo abierto y fácil mantenimiento, para ser utilizada con fines experimentales por la comunidad científica. El presente documento proporciona una descripción de los principales criterios de diseño y codificación considerados para implementar el protocolo, y expone además las principales pruebas que se han realizado con el fin de verificar su correcto funcionamiento.Postprint (published version

Drought impacts on vegetation activity, growth and primary production in humid and arid ecosystems

Ponencia presentada en: VIII Congreso de la Asociación Española de Climatología celebrado en Salamanca entre el 25 y el 28 de septiembre de 2012.[EN]We have evaluated the response of the Earth biomes to drought using a new global dataset that captures drought effects on vegetation at various time scales. We show that arid and humid biomes are both affected by drought, and that the time scale on which droughts most intensively affects vegetation plays a key role in determining the sensitivity of biomes to drought. Arid biomes respond to drought at short time scales because plants have mechanisms allowing them to rapidly adapt to changing water availability. Humid biomes also respond to drought at short time scales, probably because there plant species show a poor adaptability to water shortage. Sub-humid biomes respond to drought at long time scales because plants are adapted to withstand water deficit, but they lack the rapid post-drought recovery observed in arid biomes.[ES]En este trabajo se evalúa la respuesta de los diferentes biomas terrestre a la sequía mediante una base de datos nueva que captura el efecto de la sequía sobre la vegetación a diferentes escalas temporales. Se ha comprobado que los biomas característicos de zonas áridas y húmedas se ven afectados por la sequía, y que la escala temporal de la sequía juega un papel clave al determinar la sensibilidad de los biomas a la sequía. Los biomas áridos responden a las sequías medidas a escalas temporales cortas, debido a que las plantas tienen mecanismos que les permitan adaptarse rápidamente a la disponibilidad de agua. Los biomas húmedos también responden a la sequía a escalas temporales cortas, probablemente debido a que las especies ubicadas allí muestran una mala adaptación a la escasez de agua. Los biomas subhúmedos responden a la sequía a escalas de tiempo más largas, porque las plantas están adaptadas para soportar el déficit de agua, pero carecen de la rápida recuperación observada tras la sequía en los biomas áridos.This work was supported by projects financed by the Spanish Commission of Science and Technology (CGL2011-27574-CO2-02, CGL2011-27536 and CGL2011-26654) and the Aragón Government. J.J.C. thanks the support of ARAID and A.S-L. was supported by a postdoctoral fellowship from the Generalitat de Catalunya (2009 BP-A 00035)

Health status in gilthead seabream (Sparus aurata) juveniles fed diets devoid of fishmeal and supplemented with Phaeodactylum tricornutum

To enhance fish general health, feeds can be supplemented with health-promoting additives, reducing the need to use chemotherapeutics. Incorporation of marine algae biomasses in aquafeeds has been shown to improve fish immune status by enhancing innate immune response. This study evaluated the effects of Phaeodactylum tricornutum incorporation in feed by two different processes, either as freeze-dried biomass or broken cell wall biomass, on fish health status and performance. Triplicate groups of gilthead seabream juveniles (13.3 ± 0.3 g) were either fed a control diet (CTRL) with an extreme (i.e., 0% fishmeal), nutritionally balanced, formulation, or two experimental diets formulated as the CTRL with 1% inclusion of the microalga P. tricornutum at the expense of wheat meal: BC diet contains P. tricornutum broken cells and WC diet microalgae whole cells. After 2 and 12 weeks of feeding, blood was collected for hematological procedures, whereas plasma and mucus were sampled for immune parameters. Head-kidney, liver, and white skeletal muscle were also collected for gene expression measurements. No major differences were observed in hematological nor plasma humoral parameters after 12 weeks irrespective of dietary treatment. Arrays of 29–31 genes were analyzed in the different tissues, revealing an early dietary effect (2 weeks) in a tissue-specific pattern. In the liver, the major effect was found in the GH/IGF axis and in muscle there was a late downregulation of myostatin (mstn) gene, mainly due to WC diet, even though all fish had similar growth performance. Regarding the head-kidney, BC diet led to alpha-2-macroglobulin (a2m) gene upregulation. Also, the same treatment showed increased mucus alternative complement pathway and bactericidal activity at 2 and 12 weeks, respectively. Hence, it seems that BC diet has a potential stimulatory effect that might be relevant as a prophylactic measure before a predictable stressful event.This work has been funded under the EU FP7 by the MIRACLES project No. 613588: Multi-product Integrated bioRefinery of Algae: from Carbon dioxide and Light Energy to high-value Specialties and by national funds through FCT - Foundation for Science and Technology within the scope of UIDB/04423/2020 and UIDP/04423/2020. B. Reis, L. Ramos-Pinto, B. Costas, and S. Engrola were supported by the Portuguese Foundation for Science and Technology (PD/BDE/129262/2017, PD/BDE/114436/2016, IF/00197/ 2015, and IF/00482/2014, respectively)

Telemedicine, Psychology and Diabetes: Evaluation of results and cost analysis

The Psychosocial Aspects of Diabetes (PSAD) Study Group is an official Study Group of the European Association for the Study of Diabetes (EASD).AIMS: Evidences of benefits of telemedicine in T1DM patients on continuous subcutaneous insulin infusion (CSII) treatment are limited. Aims: 1) to analyse the differences in clinical and psychological variables between subjects with T1DM on CSII treatment who were included in a Telecare (TC) program, and subjects with T1DM on CSII treatment who received Conventional care (CC); 2) Perform a cost analysis of the use of telemedicine in DM1 patients treated with CSII (TC versus CC). METHODS and PARTICIPANTS: Cross-over randomized clinical trial with duration of 18 months. 51 patients signed informed consent. Participants were randomly assigned to receive TC program or CC during 6 months, and after a 3 months wash-out period, patients changed to CC or to TC respectively. TC program included monthly visits using an Internet platform. CC comprised face-to-face visits every three months. Sociodemographic, clinical and psychological data was measured at the beginning and at the end of TC and CC. The direct and indirect costs were also measured. T Student was performed to assess differences between first and last visits in both groups (TC / CC). RESULTS: Patients with telemedicine at the end of treatment, have fewer hyperglycemia / week, less distress and greater adherence. Considering both direct and indirect costs, the cost per treatment (TC / CC) is similar. CONCLUSIONS: Telemedicine has significant implications for clinical and psychological variables and has the same cost (total) than the conventional treatment. Therefore, it can be a useful alternative for treatment of DM1 patients with CSII. However, studies with a larger sample size are needed.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Evaluación de la desnutrición hospitalaria dentro de los hospitales pediátricos por los Grupos de Apoyo Nutricional (GAN): primera experiencia cubana

La desnutrición hospitalaria constituye un importante problema de salud tanto en países desarrollados como subdesarrollados. La derogación de importantes cifras monetarias en el tratamiento de los niños ingresados en salas de cuidados críticos, servicios de oncología, quemados pudieran ser disminuidas si se prestara mayor atención por el personal directivo y médico a los cuidados nutricionales. En el presente reporte se hace un análisis de la epidemiología de la desnutrición hospitalaria exponiéndose a través de los resultados de los dos estudios pioneros de la desnutrición en hospitales pediátricos de Ciudad de la Habana con el objetivo de resaltar la importancia de la metodología de los Grupos de Apoyo Nutricional en el enfoque integral de la desnutrición hospitalaria como herramienta. Los autores concluyen que la desnutrición hospitalaria puede variar en cuanto a su incidencia de acuerdo a la complejidad de las patologías que en el mismo se atienden y que los Grupos de Apoyo Nutricional y/o las Unidades de Nutrición Enteral Pediátricas adjuntas a dichos grupos las pueden incidir de forma positiva en disminuir el impacto de la desnutrición hospitalaria