Fast emergency paths schema to overcome transient link failures in ospf routing

A reliable network infrastructure must be able to sustain traffic flows, even when a failure occurs and changes the network topology. During the occurrence of a failure, routing protocols, like OSPF, take from hundreds of milliseconds to various seconds in order to converge. During this convergence period, packets might traverse a longer path or even a loop. An even worse transient behaviour is that packets are dropped even though destinations are reachable. In this context, this paper describes a proactive fast rerouting approach, named Fast Emergency Paths Schema (FEP-S), to overcome problems originating from transient link failures in OSPF routing. Extensive experiments were done using several network topologies with different dimensionality degrees. Results show that the recovery paths, obtained by FEPS, are shorter than those from other rerouting approaches and can improve the network reliability by reducing the packet loss rate during the routing protocols convergence caused by a failure.Comment: 18 page

Tras las ruinas del poema: el agotamiento lírico como clave interpretativa en Mordiendo el frío de Edwin Madrid (Crítica)

El autor interpreta el poemario Mordiendo el frío, del ecuatoriano Edwin Madrid. Lo hace a la luz de una afirmación del filósofo Alain Badiou: que el poema actual tiene solo una responsabilidad estética, ya no filosófica. Barreto afirma que Madrid muestra el deslinde entre filosofía y el poema moderno, para ello, se vale del lenguaje coloquial, el humor y la gozosa levedad sexual de Valerio, el personaje poético del libro. Según Barreto, el lenguaje poético, vacío, ya no cataliza la experiencia del sujeto: deviene en pura información. Añade que tal desconfianza en la poesía y el lenguaje líricos constituye una velada crítica a la institucionalización del género. Así, esta obra mostraría el agotamiento lírico de cierta poesía moderna. Barreto sugiere que dicho agotamiento se inserta en las condiciones globalizadas de las sociedades actuales, y que participa de la muerte de la experiencia en el sujeto moderno. Concluye que Madrid no lamenta la ruptura entre filosofía y poesía, por el contrario, busca trazar nuevas sensibilidades, signadas por la cotidianidad posmoderna.The author construes Mordiendo el frío, a poem book by the Ecuadorian writer Edwin Madrid. He does so in the light of philosopher Alain Badiou’s assertion: that current poetry has only an a esthetic responsibility, and not philosophical anymore. Barreto claims that Madrid shows us the detachment between philosophy and modern poetry, he achieves this by using colloquial language, humor, and the joyful sexual flippancy of Valerio, the poetic character of the book. According to Barreto, the poetic language, void of meaning, does not grasp the person’s experience: it turns out to be a mere report. This wariness about poetry and lyric language is a veiled criticism to the institutionalization of the genre, the author adds. Hence, this piece would show the lyric exhaustion of certain modern poetry. Barreto proposes that such exhaustion is embedded in the globalized conditions of today’s society, and that it plays a part in the death of experience of the modern person. Madrid closes with not lamenting the break up between philosophy and poetry, on the contrary, he strives to devise new sensitivities, marked by the everyday of post-modernism

Equation of state and transport processes in self--similar spheres

We study the effect of transport processes (diffusion and free--streaming) on a collapsing spherically symmetric distribution of matter in a self--similar space--time. A very simple solution shows interesting features when it is matched with the Vaidya exterior solution. In the mixed case (diffusion and free--streaming), we find a barotropic equation of state in the stationary regime. In the diffusion approximation the gravitational potential at the surface is always constant; if we perturb the stationary state, the system is very stable, recovering the barotropic equation of state as time progresses. In the free--streaming case the self--similar evolution is stationary but with a non--barotropic equation of state.Comment: 9 pages, 2 figure

The use of natural pigments in the treatment of leathers: identification under electronic microscopy (SEM-EDX) in experimental Stone tools

El trabajo sobre cuero ha sido ampliamente documentado en Patagonia meridional, pudiendo identificarse el uso de sustancias colorantes en su tratamiento, no sólo por cuestiones decorativas sino también para una mejor preservación del material. A nivel arqueológico, la evidencia de este tratamiento muchas veces resulta en una posible identificación a partir del estudio de otros materiales (líticos, óseos, etc.). Por lo tanto, el siguiente trabajo tiene por objetivo presentar los resultados obtenidos de una serie experimental para identificar residuos generados en el tratamiento del cuero y el uso de sustancias colorantes. La metodología aplicada incluye el análisis funcional y de residuos, a partir de estudios morfológicos y de composición elemental (SEM-EDX). Los resultados obtenidos permitieron registrar caracteres morfológicos diagnósticos y composicionales para la identificación de los residuos observados; al igual que comenzar a generar una colección de referencia para indagar acerca de las posibilidades técnicas de esta metodología y su aplicación a diferentes conjuntos líticos arqueológicos.In archaeological sites of southern Patagonia the work on hide and other animals remains has been widely documented and also the use of coloring substances in their treatment, not only for decorative reasons but also for better preservation of the material. However, archaeological identification of this treatment, often results in a possible identification from the analysis of other materials (lithics, bones, etc.). Therefore, this work present the results of an experimental series manufactured for the identification of residues generated on hide working and the use of natural pigments in their treatment. This investigation includes functional and residue analysis (morphological studies and elemental composition, SEM-EDX). The results allowed identifying certain morphological and compositional attributes to identified residues and also generate a reference collection to inquire about the technical possibilities of this methodology in its application to the archaeological recor

The Post-Quasistatic Approximation as a test bed for Numerical Relativity

It is shown that observers in the standard ADM 3+1 treatment of matter are the same as the observers used in the matter treatment of Bondi: they are comoving and local Minkowskian. Bondi's observers are the basis of the post--quasitatic approximation (PQSA) to study a contracting distribution of matter. This correspondence suggests the possibility of using the PQSA as a test bed for Numerical Relativity. The treatment of matter by the PQSA and its connection with the ADM 3+1 treatment are presented, for its practical use as a calibration tool and as a test bed for numerical relativistic hydrodynamic codes.Comment: 4 pages; to appear as a Brief Report in Physical Review