Hamilton-Jacobi theory in multisymplectic classical field theories

The geometric framework for the Hamilton-Jacobi theory developed in previous works is extended for multisymplectic first-order classical field theories. The Hamilton-Jacobi problem is stated for the Lagrangian and the Hamiltonian formalisms of these theories as a particular case of a more general problem, and the classical Hamilton-Jacobi equation for field theories is recovered from this geometrical setting. Particular and complete solutions to these problems are defined and characterized in several equivalent ways in both formalisms, and the equivalence between them is proved. The use of distributions in jet bundles that represent the solutions to the field equations is the fundamental tool in this formulation. Some examples are analyzed and, in particular, the Hamilton-Jacobi equation for non-autonomous mechanical systems is obtained as a special case of our results.Comment: 44 p

In(Ga)As self-assembled quantum ring formation by molecular beam epitaxy

The effect of growth conditions on the morphological properties of InAs/GaAs(001) quantum dots covered by a thin (<3 nm) GaAs cap has been studied by atomic force microscopy. Each dot turns into an elongated nanostructure at 540 °C upon deposition of the cap in As4 atmosphere, while structures with two humps are obtained when capping at 500 °C. The use of As2 atmosphere instead of As4 at 500 °C leads to the formation of quantum rings. Photoluminescence spectroscopy and polarization photoluminescence (PL) at 15 K show dramatic changes due to the different kinds of confinement. This allows the possibility of tailoring PL emission by controlling the size and shape.The authors would like to thank J. L. Costa Kramer for help during writing and Axel Lorke and Richard Warburton for fruitful discussions. This work was partially supported by Project No. 07T/0062/2000 of the Comunidad Autónoma de Madrid, Project No. TIC99-1035-C02, Nanoself Project No. TIC2002-04096-C03 and by Nanomat of the EC Growth Program, Contract no. G5RD-CT-2001-00545.Peer reviewe

Cryopreservation of GABAergic neuronal precursors for cell-based therapy

Cryopreservation protocols are essential for stem cells storage in order to apply them in the clinic. Here we describe a new standardized cryopreservation protocol for GABAergic neural precursors derived from the medial glanglionic eminence (MGE), a promising source of GABAergic neuronal progenitors for cell therapy against interneuron-related pathologies. We used 10% Me2 SO as cryoprotectant and assessed the effects of cell culture amplification and cellular organization, as in toto explants, neurospheres, or individualized cells, on post-thaw cell viability and retrieval. We confirmed that in toto cryopreservation of MGE explants is an optimal preservation system to keep intact the interneuron precursor properties for cell transplantation, together with a high cell viability (>80%) and yield (>70%). Postthaw proliferation and self-renewal of the cryopreserved precursors were tested in vitro. In addition, their migration capacity, acquisition of mature neuronal morphology, and potency to differentiate into multiple interneuron subtypes were also confirmed in vivo after transplantation. The results show that the cryopreserved precursor features remained intact and were similar to those immediately transplanted after their dissection from the MGE. We hope this protocol will facilitate the generation of biobanks to obtain a permanent and reliable source of GABAergic precursors for clinical application in cell-based therapies against interneuronopathies.Ministerio de Economía y Competitividad 09-07746 y 12-36853Junta de Andalucía CTS- 256

The order of knowledge and digital organization

[Resumen] Foucault establece el orden de los saberes, donde el orden es la ley interior de las cosas mediante la cual se relacionan unas con otras. Este orden es alterado por el lenguaje y, una vez alterado, posibilita la organización de los saberes y del conocimiento científico. Este desplazamiento a través del lenguaje inicia, a su vez, la taxonomía y la clasificación. La red digital ha provocado revoluciones en el contexto científico y epistémico, y la nueva materialidad digital transforma la ciencia misma y su forma de organización. El futuro de la organización de la web depende de cómo se articule la web semántica, esta ha de ser interoperable sin estructuras previas de jerarquización y exclusión, una web asociativa. El gran potencial de la web semántica no puede establecerse con ordenación y jerarquía sino con integración, colaboración y cooperación

A aplicação do crowdsourcing e o modelo de Bazaar no desenvolvimento de classificações de bibliotecas: uma avaliação da Classificação Open Shelves

This paper presents a discussion of crowdsourcing approaches to knowledge organization and more specifically to the development of classification schemes. It analyzes the case of Open Shelves Classification, a terminated project that was developed by the LibraryThing community following the "open source model", and assesses its outcomes from methodological and sociological points of view. Working with all the documentation of the project that is freely available, the text conducts an analysis of the project following the structure of the methodological lessons for open source (Bazaar model) presented by Eric Raymond in his seminal work "The Cathedral and the Bazaar" and complementing it with the discussion of the sociological aspects presented in "Homesteading the Noosphere" and other writings. The paper concludes with some recommendations for the success of open source projects and some possibilities of research for crowdsourcing projects and social epistemology.O trabalho apresenta uma discussão sobre as abordagens de crowdsourcing para organização do conhecimento e, mais especificamente, para o desenvolvimento de sistemas de classificação. Além de analisar o caso da Open Shelves Classification, um projeto finalizado e desenvolvido pela comunidade LibraryThing seguindo o "modelo de código aberto", e avaliar o resultado de pontos de vista metodológicos e sociológicos, o artigo trabalha com a documentação do projeto disponível, realiza uma análise do projeto seguindo a estrutura dos pontos metodológicos para projetos de código aberto (modelo Bazar) apresentados por Eric Raymond em seu trabalho seminal "A Catedral e o Bazaar" e complementa com a discussão dos aspectos sociológicos apresentados em "Homesteading the Noosphere" e outras literaturas. A conclusão deste trabalho inclui recomendações para o sucesso de projetos de código aberto e algumas possibilidades de pesquisa para projetos de crowdsourcing e epistemologia social

Gymnocarpio dryopteridis-Abietion lasiocarpae nomen dubium et nomen ambiguum

Se propone una nueva clasificación para Gymnocarpio dryopteridis-Abietion lasiocarpa

Solving Sudoku with Membrane Computing

Sudoku is a very popular puzzle which consists on placing several numbers in a squared grid according to some simple rules. In this paper we present an efficient family of P systems which solve sudokus of any order verifying a specific property. The solution is searched by using a simple human-style method. If the sudoku cannot be solved by using this strategy, the P system detects this drawback and then the computations stops and returns No. Otherwise, the P system encodes the solution and returns Yes in the last computation step.Ministerio de Ciencia e Innovación TIN2008-04487-EMinisterio de Ciencia e Innovación TIN2009–13192Junta de Andalucía P08-TIC-0420

How Does a P System Sound?

P systems are computational devices versatile enough to represent many real-life scenarios. In this paper, we present a first interpretation for P systems where a computation produces a set of sounds. The idea is to associate sounds to the application of specific rules in the P system. The application of such rules produces sounds of one time unit. Different rules produce different sounds. The combination of such sounds along time can be interpreted as music.Ministerio de Ciencia e Innovación TIN2008-04487-EMinisterio de Ciencia e Innovación TIN-2009-13192Junta de Andalucía P08-TIC-0420

Spike Processing on an Embedded Multi-task Computer: Image Reconstruction

There is an emerging philosophy, called Neuro-informatics, contained in the Artificial Intelligence field, that aims to emulate how living beings do tasks such as taking a decision based on the interpretation of an image by emulating spiking neurons into VLSI designs and, therefore, trying to re-create the human brain at its highest level. Address-Event-Representation (AER) is a communication protocol that has embedded part of the processing. It is intended to transfer spikes between bioinspired chips. An AER based system may consist of a hierarchical structure with several chips that transmit spikes among them in real-time, while performing some processing. There are several AER tools to help to develop and test AER based systems. These tools require the use of a computer to allow the higher level processing of the event information, reaching very high bandwidth at the AER communication level. We propose the use of an embedded platform based on a multi-task operating system to allow both, the AER communication and processing without the requirement of either a laptop or a computer. In this paper, we present and study the performance of a new philosophy of a frame-grabber AER tool based on a multi-task environment. This embedded platform is based on the Intel XScale processor which is governed by an embedded GNU/Linux system. We have connected and programmed it for processing Address-Event information from a spiking generator.Ministerio de Educación y Ciencia TEC2006-11730-C03-0