Exact solutions of the Dirac equation and induced representations of the Poincare group on the lattice

We deduce the structure of the Dirac field on the lattice from the discrete version of differential geometry and from the representation of the integral Lorentz transformations. The analysis of the induced representations of the Poincare group on the lattice reveals that they are reducible, a result that can be considered a group theoretical approach to the problem of fermion doubling.Comment: LaTeX, 4 pages, (late submission

Continuous vs. discrete models for the quantum harmonic oscillator and the hydrogen atom

The Kravchuk and Meixner polynomials of discrete variable are introduced for the discrete models of the harmonic oscillator and hydrogen atom. Starting from Rodrigues formula we construct raising and lowering operators, commutation and anticommutation relations. The physical properties of discrete models are figured out through the equivalence with the continuous models obtained by limit process.Comment: LaTeX, 14 pages (late submission

Causal spin foams and the ontology of spacetime

We present some modern theories on the structure of spacetime that can be classified as relational theories in the direction of Leibniz's ontology. In order to analyze the nature of spacetime we consider three levels of knowledge -observational, theoretical and ontological- to which the different models can be adscribed. Following similar approach to these models mentioned at the first sections, we present our theoretical model of the structure of spacetime, some physical applications, and the ontological interpretation of the model.Comment: Communication presented to the Second International Conference on the Ontology of Spacetime, 9-11, June 2006, Concordia University, Montreal. Latex. 22 page

El Seminari de Pedagogia del Col·legi Oficial de Doctors i Llicenciats de València : la lluita per la democratització de l’educació i la utopia pedagògica, 1966-1976

Al llarg dels anys seixanta del segle XX es produirà una transformació molt significativa en les funcions habituals dels col·legis oficials de doctors i llicenciats. En els anys finals del franquisme els col·legis tindran una presència social i política fonamental, en especial pel que fa a la lluita per aconseguir un sistema educatiu democràtic en una societat que també ho fóra. Estos organismes professionals acullen en els anys setanta algunes de les iniciatives més fructíferes de renovació pedagògica que es plantegen en el país, i donen als grups de docents que les sustenten —en un context autoritari i repressor, d’absència de llibertats civils i polítiques— cobertura legal, mitjans i suport institucional. El Seminari de Pedagogia del Col·legi Oficial de Doctors i Llicenciats de València entre 1966-1976 és un excel·lent exemple de tot això. Un col·lectiu, reduït però compromès, de docents d’ensenyança primària i secundària que inicia el seu camí en el curs escolar 1965-1966 i que es constitueix en Comissió d’Estudis Pedagògics, i que, al llarg d’una dècada fonamental, tindrà un paper d’indubtable importància en la lluita per l’extensió en el País Valencià de la renovació pedagògica i la difusió dels mètodes i plantejaments de l’escola activa, d’un credo pedagògic en gran manera clarament deutor del pensament d’Henri Wallon. Dues fites d’enorme importància i significació en eixa tasca seran l’elaboració, discussió i difusió d’Una alternativa per a l’ensenyança en el País Valencià en 1975 i la posada en marxa l’any següent de la I Escola d’Estiu del País Valencià.During the 1960s a very significant transformation will take place in the usual functions of the Doctors’ and Graduates’ Associations. In the last years of Franco Regime, the Doctors’ and Graduates’ Associations had a social and political presence that will become essential in the fight for achieving a democratic educational system in a democratic society. During the seventies, these official organisations provided some of the most productive initiatives of pedagogical renovation in the country, giving the teachers who sustain them —in the authoritarian and repressive context of the moment and the absence of civil and political liberties— legal coverage, resources and institutional support. The Seminari de Pedagogia of the Valencian Doctors’ and Graduates’ Association is an excellent example of it. A small but compromised group of primary and secondary education teachers that constituted in 1965- 1966 a Commission of Pedagogical Studies, and that throughout a decade will play a fundamental role in the fight for the expansion of Pedagogical Renovation to the Valencian Country and the diffusion of the methods and approaches of the Progressive School, a pedagogical creed clearly debtor of Henri Wallon’s thought. Two milestones of enormous importance and significance in this task will be the elaboration, discussion and diffusion of an Alternativa (Alternative) for teaching in the Valencian Country in 1975 and the start, in the next year, of the First Summer School of the Valencian [email protected]

Study of the effects of in vivo telomere elongation mechanisms in cancer and aging

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Bioquímica. Fecha de lectura: 30-01-2020Short and dysfunctional telomeres are sufficient to induce a persistent DNA damage response at chromosome ends, which leads to the induction of senescence and/or apoptosis and trigger age-related pathologies including a group of diseases known as “telomere syndromes”, and shorter lifespans in mice and humans. In turn, maintenance of longer telomeres owing to telomerase overexpression in adult tissues delays aging and increases mouse longevity. This opens the possibility of using telomerase activation as a potential therapeutic strategy to rescue short telomeres both in telomere syndromes and in agerelated diseases. However, telomerase has been found re-activated in most of human cancers making telomerase therapy a potential risk in treating short telomere accumulation. In this regard, telomere elongation avoiding the overexpression of telomerase could be a safer answer to prevent short telomeres delaying or even avoiding short telomere related pathologies. Based on this, the first aim of this thesis is to test the safety of telomerase gene therapy in the context of a cancer prone mouse model. To this end, we treated a well stablished K-Ras mediated lung cancer mouse model with AAV9-Tert for telomerase overexpression. As control, we also treated mice with AAV9 vectors carrying a catalytically inactive form of Tert, known to inhibit endogenous telomerase activity. We found that overexpression of Tert does not accelerate the onset or progression of lung carcinomas, even when in the setting of a p53-null background. These findings indicate that telomerase activation by using AAV9-mediated Tert gene therapy has no detectable cancer-prone effects in the context of oncogene-induced mouse tumors. On the other hand, the second aim of this thesis is to address whether embryonic stem (ES) cells carrying telomeres elongated in the absence of genetic modifications could contribute to the formation of a healthy organism and whether these elongated telomeres may have any deleterious effects. In this regard, we generated mice in which 100% of their cells are derived from hyper-long telomere ES cells. We found that these mice have longer telomeres and less DNA damage with aging. Interestingly, they are leaner than normal due to lower body fat accumulation. They also show less metabolic aging as indicated by lower cholesterol and LDL levels, and by improved glucose and insulin tolerance. Importantly, mice with hyper-long telomeres have less cancer and show an increased longevity. These findings demonstrate that longer telomeres than normal in a given species are not deleterious but instead, show beneficial effects.La acumulación de telomeros cortos es suficiente para inducir una respuesta de daño persistente en el ADN, induciendo sensecencia y/o apoptosis. Este fenómeno es la principal causa de las patologías relacionadas con la edad, incluyendo un grupo de enfermedades conocidas como “síndromes teloméricos”, así como de una menor esperanza de vida tanto en ratones como en humanos. Consecuentemente, la sobreexpresión de telomerasa en adultos es capaz de retrasar el envejecimiento y aumentar la esperanza de vida en ratones, pudiendo usar esta enzima como una potencial estrategia terapéutica para tratar estas enfermedades. Sin embargo, la telomerasa se ha visto re-activada en la mayoría de cánceres humanos, haciendo de esta terapia un riesgo potencial a la hora de tratar las enfermedades relacionadas con los telómeros. A este respecto, la elongación de los telómeros evitando la sobreexpresión de telomerasa podría ser una forma más segura de tratar dichas patologías retrasando o incluso evitando la aparición de telómeros cortos. En base a esto, el primer objetivo de esta tesis es probar la seguridad de la terapia génica con telomerasa en el contexto de un modelo animal propenso a padecer cáncer. Para ello, hemos tratado un modelo de ratón muy establecido que desarrolla cáncer de pulmón con AAV9-Tert. Como control, también hemos tratado estos animales con vectores virales AAV9 que contienen una forma catalíticamente inactiva de Tert, conocida por inhibir la actividad telomerasa endógena. Los resultados de este ensayo mostraron que la sobreexpresión de Tert no es capaz de acelerar la aparición ni la progresión del cáncer de pulmón, incluso en un fondo genético que carece de p53. Este descubrimiento indica que la activación de telomerasa usando la terapia génica mediada por vectores AAV9 no tiene ningún efecto oncogénico en el cáncer de pulmón en ratones. Por otro lado, el segundo objetivo de esta tesis ha sido demostrar si células madre embrionarias poseedoras de telómeros elongados sin necesidad de modificaciones genéticas podrían contribuir a la formación de organimos sanos y si estos telómeros podrían tener algún efecto deletéreo. Por ello, fuimos capaces de generar ratones en los que el 100% de sus células derivan de las células madre con telómeros súper-largos. Encontramos que estos animales presentan telómeros más largos y menor daño en el ADN con la edad. Interesantemente, eran más delgados de lo normal debido a una menor acumulación de grasa corporal. También mostraron una menor edad metabólica indicada por bajos niveles de colesterol y LDL y por una mejorada tolerancia a la glucosa y la insulina. Importantemente, estos animales tienen menos cáncer y una mayor longevidad. Estos descrubrimientos demuestran que tener telómeros más largos de los habituales para una especie no es deletéreo, sino que presenta efectos beneficiosos

Design and Development of a LEDs’ Roulette for its Application in Microscopy

The main goal of this experiment was the creation of a LED roulette that will be used in microscopy in such a way that samples can be analyze not only with white light, but also with LEDs with different wavelengths. Moreover, this experiment was focused in the creation of a calibration protocol for the LEDs, based on a sensor (photodetector), in such a way that it is possible to quantify as a function of the distance between the light source and the sample, as well as taking into account the aperture angle of the light source, the energy that will arrive to the sample for its posterior analysis. Therefore, this protocol would be used as a baseline for other experiment so that the correct components, the ones that better fits the needs of the new test, can be selected.Grado en Ingeniería Biomédic

Representations of the discrete inhomogeneous Lorentz group and Dirac wave equation on the lattice

We propose the fundamental and two dimensional representation of the Lorentz groups on a (3+1)-dimensional hypercubic lattice, from which representations of higher dimensions can be constructed. For the unitary representation of the discrete translation group we use the kernel of the Fourier transform. From the Dirac representation of the Lorentz group (including reflections) we derive in a natural way the wave equation on the lattice for spin 1/2 particles. Finally the induced representation of the discrete inhomogeneous Lorentz group is constructed by standard methods and its connection with the continuous case is discussed.Comment: LaTeX, 20 pages, 1 eps figure, uses iopconf.sty (late submission

Viejas variedades, nuevas oportunidades: un trabajo de investigación saca a la luz viejas variedades de vid desconocidas en peligro de extinción

El estudio molecular de la colección de vides recopiladas por la antigua Estación de Viticultura y Enología de Movera, actualmente integrada en el Centro de Transferencia Agroalimentaria del Departamento de Agricultura y Alimentación del Gobierno de Aragón, realizado en colaboración con la Estación Experimental de Aula Dei (CSIC), ha permitido descubrir un número importante de variedades desconocidas en peligro de extinción que podrían ser autóctonas de la región

The double torus as a 2D cosmos: groups, geometry and closed geodesics

The double torus provides a relativistic model for a closed 2D cosmos with topology of genus 2 and constant negative curvature. Its unfolding into an octagon extends to an octagonal tessellation of its universal covering, the hyperbolic space H^2. The tessellation is analysed with tools from hyperbolic crystallography. Actions on H^2 of groups/subgroups are identified for SU(1, 1), for a hyperbolic Coxeter group acting also on SU(1, 1), and for the homotopy group \Phi_2 whose extension is normal in the Coxeter group. Closed geodesics arise from links on H^2 between octagon centres. The direction and length of the shortest closed geodesics is computed.Comment: Latex, 27 pages, 5 figures (late submission to arxiv.org