Hamiltonian Noether theorem for gauge systems and two time physics

The Noether theorem for Hamiltonian constrained systems is revisited. In particular, our review presents a novel method to show that the gauge transformations are generated by the conserved quantities associated with the first class constraints. We apply our results to the relativistic point particle, to the Friedberg et al. model and, with special emphasis, to two time physics.Comment: 20 pages, Latex, references added, the "massless" sense of (87) is clarifie

Evaluación de la asignatura Exploración Topográfica Manual

[Resumen] En este artículo exponemos los objetivos generales y específicos, los contenidos y la metodología de enseñanzas y evaluación de una asignatura de libre configuración ofertada por la Escuela Universitaria de Fisioterapia de la Universidad de A Coruña, cuyo título es Exploración Topográfica Manual[Abstract] A description is made o/ the general and specific aims, content, teaching method and evaluation of an optinal course offered at the University School o/ Physical Therapy o/ La Coruña, Spain, known as Manual Topographic Examination

Snail blocks the cell cycle and confers resistance to cell death

The Snail zinc-finger transcription factors trigger epithelial-mesenchymal transitions (EMTs), endowing epithelial cells with migratory and invasive properties during both embryonic development and tumor progression. During EMT, Snail provokes the loss of epithelial markers, as well as changes in cell shape and the expression of mesenchymal markers. Here, we show that in addition to inducing dramatic phenotypic alterations, Snail attenuates the cell cycle and confers resistance to cell death induced by the withdrawal of survival factors and by pro-apoptotic signals. Hence, Snail favors changes in cell shape versus cell division, indicating that with respect to oncogenesis, although a deregulation/increase in proliferation is crucial for tumor formation and growth, this may not be so for tumor malignization. Finally, the resistance to cell death conferred by Snail provides a selective advantage to embryonic cells to migrate and colonize distant territories, and to malignant cells to separate from the primary tumor, invade, and form metastasis

Microbially-Mediated Fluorescent Organic Matter Transformations in the Deep Ocean. Do the chemical precursors matter?

Original research paperThe refractory nature of marine dissolved organic matter (DOM) increases while it travels from surface waters to the deep ocean. This resistant fraction is in part composed of fluorescent humic-like material, which is relatively difficult to metabolize by deep water prokaryotes, and it can also be generated by microbial activity. It has been recently argued that microbial production of new fluorescent DOM (FDOM) requires the presence of humic precursors in the surrounding environment. In order to experimentally test how the chemical quality of the available organic compounds influences the production of new FDOM, three experiments were performed with bathypelagic Atlantic waters. Microbial communities were incubated in three treatments which differed in the quality of the organic compounds added: (i) glucose and acetate; (ii) glucose, acetate, essential amino acids, and humic acids; and (iii) humic acids alone. The response of the prokaryotes and the production of FDOM were simultaneously monitored. Prokaryotic abundance was highest in treatments where labile compounds were added. The rate of humic-like fluorescence production, scaled to prokaryotic abundance, varied depending on the quality of the additions. The precursor compounds affected the generation of new humic-like FDOM, and the cell-specific production of this material was higher in the incubations amended with humic precursors. Furthermore, we observed that the protein-like fluorescence decreased only when fresh amino acids were added. These findings contribute to the understanding of FDOM variability in deep waters and provide valuable information for studies where fluorescent compounds are used in order to track water masses and/or microbial processes.Spanish Ministry of Economy and Competitivity, CSIC, ESF and Danish Research Council for Independent ResearchVersión del edito

Optimization of sonic crystal attenuation properties by ev-MOGA multiobjective evolutionary algorithm

[EN] This paper shows a promising method for acoustic barrier design using a new acoustic material called Sonic Crystals (SCs). The configuration of these SCs is set as a multiobjective optimization problem which is very difficult to solve with conventional optimization techniques. The paper presents a new parallel implementation of a Multiobjective Evolutionary Algorithm called ev-MOGA (also known as (sic)-MOGA) and its application in a complex design problem. ev-MOGA algorithm has been designed to converge towards a reduced, but well distributed, representation of the Pareto Front (solution of the multiobjective optimization problem). The algorithm is presented in detail and its most important properties are discussed. To reduce the ev-MOGA computational cost when.Partially supported by MEC (Spanish Government) and FEDER funds: projects DPI2005-07835, MAT2006-03097 and Generalitat Valenciana (Spain) projects GV06/026, GV/2007/191Herrero Durá, JM.; Garcia-Nieto, S.; Blasco, X.; Romero García, V.; Sánchez Pérez, JV.; García-Raffi, LM. (2009). Optimization of sonic crystal attenuation properties by ev-MOGA multiobjective evolutionary algorithm. Structural and Multidisciplinary Optimization. 39(2):203-215. https://doi.org/10.1007/s00158-008-0323-7S203215392Alander J (2002) An indexed bibliography of genetic algorithms & pareto and constrainedoptimization. Tech Rep, Dpt of Information Technology, University of VaasaCantú-Paz E (1997) A survey of parallel genetic algorithms. Tech Rep 97003, Illimois Genetic Algorithms LaboratotyCervera F, Sanchis L, Sánchez-Pérez JV, Martínez-Sala R, Rubio C, Meseguer F, López C, Caballero D, Sánchez-Dehesa J (2002) Refractive acoustic devices for airborne sound. 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Morgan Kaufmann, San Francisco, pp 265–283Fonseca C, (1995) Multiobjective genetic algorithms with application to control engineeringproblems. PhD thesis, Dpt of Automatic Control and Systems Engineering, University of SheffieldFuster E, Romero-García V, García-Raffi LM, Sánchez-Pérez EA, Sopena M, Sánchez-Pérez JV (2006) A phenomenological model for sonic crystals based on artificial neural networks. J Acoust Soc Am 120(2):1–6García-Pablos D, Sigalas M, de Espinosa FM, Torres M, Kafesaki M, García, N (2000) Theory and experiments on elastic band gaps. Phys Rev Lett 84:4349–4352Gazonas GA, Weile DS, Wildman R, Mohan A (2006) Genetic algorithm optimization of phononic bandgap structures. Int J Solids Struct 43:5851–5866Hakkansson A, Cervera F, Sánchez-Dehesa J (2005) Sound focusing by flat acoustic lenses without negative refraction. 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Quantifying the decay of quantum properties in single-mode states

The dissipative dynamics of Gaussian squeezed states (GSS) and coherent superposition states (CSS) are analytically obtained and compared. Time scales for sustaining different quantum properties such as squeezing, negativity of the Wigner function or photon number distribution are calculated. Some of these characteristic times also depend on initial conditions. For example, in the particular case of squeezing, we find that while the squeezing of CSS is only visible for small enough values of the field intensity, in GSS it is independent of this quantity, which may be experimentally advantageous. The asymptotic dynamics however is quite similar as revealed by the time evolution of the fidelity between states of the two classes.Comment: Accepted versio

EL GOBIERNO CORPORATIVO UNA NECESIDAD PARA EL DESARROLLO DE LAS MIPYMES

La relevancia de que las MIPYMES puedan transitar de una nula organización interna hacia la implementación del Gobierno Corporativo (GC), será posible si se capacita a los dueños de las empresas de manera tal que todos participantes interactúen para lograr el desarrollo mediante la alineación de una política interna de crecimiento donde todos colaboren para lograr el objetivo planteado por el administrador. IMEF (2010) define (GC) como “Un conjunto de prácticas y controles cuyo objetivo es llevar una administración transparente y equitativa alineada con los intereses de sus accionistas, teniendo como premisa prevenir conflictos de intereses y posibles abusos, así como el menoscabo en el patrimonio de sus inversionistas”. De acuerdo a información de la CONDUSEF (2016) del total de las empresas en México el 99.8% corresponden a MIPyMEs, que generan el 72% del empleo y contribuyen con el 52% del PIB. Estableciéndose como agentes claves para el desarrollo económico local, sin embargo, uno de los problemas centrales que enfrentan dichas empresas es el financiamiento. Ante ello la presente investigación muestra resultados preliminares de investigación producto de la aplicación a una encuesta aplicada a una muestra 309 empresas del total de empresas en 19 estados de la república mexicana atendidas por Financiera Provident, organización que otorga financiamiento y cuenta con una experiencia de más de 130 años de presencia tanto nacional como internacional. Dentro de los resultados obtenidos es posible mencionar que el 48 %de las empresas atendidas son micro, 44% pequeñas y 8% medianas; el 80.91% desempeña su actividad en el mercado local, el 37 % se dedican al comercio, el 9.39% de los dueños cuenta con licenciatura, el 69.26% son mujeres, el 48.19 de las empresas se ubica en el Estado de Puebla, el 49% de las empresas tuvo un crecimiento regular y finalmente concluyendo con la recomendación la capacitación a los integrantes de dichas empresas en las diferentes áreas con la finalidad de buscar la implementen el GC y tener posibilidades de acceder al financiamiento

Extraction of 2′-O-apiosyl-6′-O-crotonic acid-betanin from the ayrampo seed (Opuntia soehrensii) cuticle and its use as an emitting layer in an organic light-emitting diode

The molecule 2′-O-apiosyl-6′-O-crotonic acid-betanin (called Achkiy) was obtained after an ecofriendly and low-cost purification process of the extract from the ayrampo seed cuticle. Results from EDS give us an idea of the organic elements present in the ayrampo cuticle layer composed of carbon, oxygen and nitrogen. Further characterization analysis of ayrampo extract by Fourier Transform Infrared Spectrophotometry (FTIR) corroborated the presence of characteristic functional groups corresponding to carboxyl, carbonyls, hydroxyls and secondary amines. On the other hand, we have confirmed by absortion peak the glucose, apiosyl, crotonic acid and betanin at 227 nm, 276 nm, 291 nm and 534 nm bands respectively. Mass Spectrometry (MS) characterization was used finally to identify the electroactive Achkiy molecule. This molecule was tested in an Organic Light Emitting Diode (OLED) achieving a luminance of 4.8 Cd m$^{−2}$ when bias voltage of 16.5 V and a current of 34.1 mA was applied. In addition, the irradiance generated by the Achkiy layer reaches a value of ≈ 113.3 μW m$^{−2}$ emitting light with a λ ≈ 390.10 nm. These preliminary results report an interesting molecule extracted from a natural pigment wich emits light in the blue region