Photon pair generation by intermodal spontaneous four wave mixing in birefringent, weakly guiding optical fibers

We present a theoretical and experimental study of the generation of photon pairs through the process of spontaneous four wave mixing (SFWM) in a few-mode, birefringent fiber. Under these conditions, multiple SFWM processes are in fact possible, each associated with a different combination of transverse modes for the four waves involved. We show that in the weakly guiding regime, for which the propagation modes may be well approximated by linearly polarized modes, the departure from circular symmetry due to the fiber birefringence translates into conservation rules which retain elements from azimuthal and rectangular symmetries: both OAM and parity must be conserved for a process to be viable. We have implemented a SFWM source based on a "bow-tie" birefringent fiber, and have measured for a collection of pump wavelengths the SFWM spectra of each of the signal and idler photons in coincidence with its partner photon. We have used this information, together with knowledge of the transverse modes into which the signal and idler photons are emitted, as input for a genetic algorithm which accomplishes two tasks: i) the identification of the particular SFWM processes which are present in the source, and ii) the characterization of the fiber used.Comment: 11 pages, 6 figure

Evaluation of cholinergic markers in Alzheimer's disease and in a model of cholinergic deficit

Cognitive deficits in neuropsychiatric disorders, such as Alzheimer's disease (AD), have been closely related to cholinergic deficits. We have compared different markers of cholinergic function to assess the best biomarker of cognitive deficits associated to cholinergic hypoactivity. In post-mortem frontal cortex from AD patients, acetylcholine (ACh) levels, cholinacetyltransferase (ChAT) and acetylcholinesterase (AChE) activity were all reduced compared to controls. Both ChAT and AChE activity showed a significant correlation with cognitive deficits. In the frontal cortex of rats with a selective cholinergic lesion, all cholinergic parameters measured (ACh levels, ChAT and AChE activities, "in vitro" and "in vivo" basal ACh release) were significantly reduced. AChE activity was associated to ChAT activity, and even more, to "in vivo" and "in vitro" basal ACh release. Quantification of AChE activity is performed by an easy and cheap method and therefore, these results suggest that determination of AChE activity may be used as an effective first step method to evaluate cholinergic deficits

Travels in Louisiana: journeys into ethnicity and heritage by two Hispanic groups

This thesis addresses how the notions of ethnicity and heritage are experienced, negotiated, and displayed by two Hispanic groups in Louisiana. Hispanic identity is a nebulous term anywhere and Louisiana is no exception. In this investigation the two groups- a heritage foundation of descendants of Canary Islanders and descendants of the of the Los Adaes communities- both profess Hispanic heritage, display it, and promote this heritage in divergent ways, with significant differences in the meaning of their heritages. Differences between groups are also reflected in the historical spatial representations of the two groups, with Isleños connecting with a far-away but set of islands which they visit, and the Los Adaes peoples connecting with a long gone Spanish mission and fort that can only be reached through historical recreation and storytelling. Conceptions of ethnicity can remain powerful even while the common understanding of the meaning of “Spanish” is vaguely conceived. These two groups expressing an historic Louisiana Spanish heritage are, in fact, exceedingly dissimilar

Facilitation of cholinergic transmission by combined treatment of ondansetron with flumazenil after cortical cholinergic deafferentation

We have studied the effects of concomitant blockade of 5-HT(3) and GABA(A) receptors on acetylcholine (ACh) release in the frontal cortex of rats with a selective cholinergic lesion. Lesions were performed by microinjection of the cholinergic toxin 192 IgG-saporin into the nucleus basalis magnocellularis. Single treatment with either the 5-HT(3) receptor antagonist ondansetron, 0.1 microg/kg, or the GABA(A) receptor benzodiazepine site antagonist flumazenil, 10 mg/kg, did not affect ACh release. However, the combined ondansetron + flumazenil administration significantly increased ACh release to a similar extent as a depolarising stimulus with K(+), 100 mM, at both 7 and 30 days post-lesion. Cortical perfusion with the combined ondansetron + flumazenil treatment also increased [(3)H]ACh efflux "in vitro" 30 days after lesion, suggesting that local events within the frontal cortex may participate in the interaction of ondansetron with GABAergic neurons, modulating ACh release in situations of cholinergic hypoactivity. No differences in the expression of 5-HT(3) and GABA(A) receptors in the frontal cortex were found after the cholinergic lesion. These results suggest that a combined ondansetron + flumazenil treatment would contribute to restoring a diminished cholinergic function and may provide a basis for using this treatment in the therapy of cognitive disorders associated with degeneration of the cholinergic system

Gestión de la información territorial de salud: México

Este trabajo es parte del proyecto de investigación del observatorio geográfico de salud y riesgos en México, aprobado por el CONACYT. El objetivo de este trabajo es presentar la gestión de la información territorial de salud en específico de la morbilidad general de México. Con un enfoque multiescalar. La Organización Mundial de la Salud define a la salud no solo como la ausencia de la enfermedad, sino como el estado completo de bienestar físico, social y psíquico de la población, aunado al aspecto medioambiental. Lo que implica que los contextos locales, regionales y globales tienen influencia en el estado de salud de la población. De ahí la importancia de la gestión de la información territorial a varias escalas de análisis, para generar bases de datos e indicadores que reflejen la salud de la población y las características de los lugares en donde habita esa población. En México existen datos de salud, sin embargo no están georeferenciados, por lo que una de las etapas en este proyecto es el diseño de las bases de datos espaciales, a fin de detectar los problemas a diversas escalas geográficas: regionales, estatales, a nivel de jurisdicción sanitaria, zonas metropolitanas y municipales, con el propósito de proponer estrategias focalizadas. Las bases de datos espaciales incluyen cinco grandes grupos de información: geográficos, de distribución de la población; de salud: mortalidad, morbilidad, servicios públicos de salud; socioeconómicos y riesgos a la salud. La implementación de las geotecnologías, como los Sistemas de información Geográfica son fundamentales cuando se trata de una gran cantidad de unidades espaciales o una gran cantidad de variables e indicadores. Disponer de bases de datos espaciales actualizadas son la base para la generación de cartografía para la ordenación territorial y para la toma de decisiones. A partir de las bases de datos se efectuarán análisis geoestadísticos, generación de indicadores y cartografía entre otros productos y estarán en la web para la consulta

Modelización espacial de trips (insecta: thysanoptera) en el cultivo de aguacate (persea americana)

SE LOGRÓ ESTABLECER MEDIANTE MODELIZACIÓN ESPACIAL LA DISTRIBUCIÓN DE LAS POBLACIONES DE TRIPS EN AGUACATE EN EL ESTADO DE MÉXICO.México es el principal productor y exportador de aguacate en el mundo. Los trips son considerados una de las principales plagas de este cultivo, ya que se alimentan del fruto pequeño y forman crestas o protuberancias, las cuales al crecer el fruto son más visibles, y este pierde valor económico. Además de este daño, las heridas causadas por los trips son el principal causante para que entre la enfermedad denominada roña de fruto. Las alternativas de control de los trips han carecido de eficacia debido, entre otras causas, a que se desconoce su distribución espacial dentro de las huertas de aguacate. Este trabajo tuvo por objetivo determinar la distribución espacial de las poblaciones de trips en aguacate mediante el uso de técnicas de estadística espacial que condujeron a la generación de mapas por medio del “krigeado”. Los resultados demostraron que las poblaciones de trips presentan una distribución de tipo agregada, que fue corroborada por los mapas de densidad. Las infestaciones se distribuyeron en el 100 % de la superficie de las dos parcelas experimentales, lo cual resulta interesante para dirigir las medidas de control sobre áreas específicas de infestación. Se logró determinar estabilidad espacial y temporal a corto plazo de las poblaciones de trips

The defence of insanity in the International Criminal Court Statute and its possible application in the case against Dominic Ongwgen

La Corte Penal Internacional busca juzgar a los responsables de graves violaciones del derecho penal internacional según su grado de responsabilidad. Evidencia de esto es la persecución y juzgamiento de Señor Dominic Ongwen, uno de los cuatro lugartenientes del Ejército de Resistencia del Señor (LRA), por los crímenes de intento de asesinato, tortura, tratos crueles, actos inhumanos, esclavitud, atentados contra la dignidad personal, saqueo, destrucción de la propiedad y persecución entre otros. Esta situación se configura dentro de un interesante contexto, pues Dominic Ongwen fue abducido a los 10 años de edad por el grupo del cual fue lugarteniente hasta antes de su captura. En razón de lo anterior, la defensa del acusado ha alegado la incapacidad mental como una de las causales eximentes de responsabilidad penal (además del estado de necesidad), de acuerdo a lo consagrado en el Articulo 31 (1)(a) del Estatuto de Roma. Esta defensa se basa en dos elementos que deben probarse; (i) la existencia de una enfermedad o deficiencia mental; y (ii) que dicha enfermedad o deficiencia tenga tales características que lo priven (destruyan) al momento de cometer el hecho ilícito de: (a) su capacidad para apreciar la naturaleza o ilicitud de la conducta; o (b) controlar esa conducta a fin de no transgredir la Ley.Dominic Ongwen - one of the four Lieutenants of the Lord's Resistance Army (LRA) -, currently is being prosecuted by the ICC for crimes against humanity and war crimes, including attempted murder, torture, cruel treatment, inhumane acts, slavery, attacks against personal dignity, looting, destruction of property and persecution. Due to the fact that Dominic Ongwen was abducted and subjected to a brutal training at the age of ten (10) by the group of which he later became, until his detention, a Lieutenant (the highest position in the LRA below the Commander-in-Chief Joseph Kony), the Defense has alleged, pursuant to article 31(1)(a) of the ICC Statute, the defense of mental insanity. Article 31(1)(a) of the ICC Statute provides the following two elements of the mental insanity defense: (i) the existence of a disease or mental defect (including its severity and its development over time); and (ii) that such disease or defect caused, at the time in which the alleged crimes were committed, the deprivation of the defendant´s capacity (a) “to appreciate the unlawfulness or nature of his conduct”; or (b) “to control his conduct according to the requirements of law”. Insanity constitutes an excluding circumstance only if both elements are fully proven by the Defense. If only one of these elements is partially proven, insanity may only be considered as a mitigating circumstance or factor in the sentence

Tidally-induced thermonuclear Supernovae

We discuss the results of 3D simulations of tidal disruptions of white dwarfs by moderate-mass black holes as they may exist in the cores of globular clusters or dwarf galaxies. Our simulations follow self-consistently the hydrodynamic and nuclear evolution from the initial parabolic orbit over the disruption to the build-up of an accretion disk around the black hole. For strong enough encounters (pericentre distances smaller than about 1/3 of the tidal radius) the tidal compression is reversed by a shock and finally results in a thermonuclear explosion. These explosions are not restricted to progenitor masses close to the Chandrasekhar limit, we find exploding examples throughout the whole white dwarf mass range. There is, however, a restriction on the masses of the involved black holes: black holes more massive than $2\times 10^5$ M$_\odot$ swallow a typical 0.6 M$_\odot$ dwarf before their tidal forces can overwhelm the star's self-gravity. Therefore, this mechanism is characteristic for black holes of moderate masses. The material that remains bound to the black hole settles into an accretion disk and produces an X-ray flare close to the Eddington limit of $L_{\rm Edd} \simeq 10^{41} {\rm erg/s} M_{\rm bh}/1000 M$_\odot$), typically lasting for a few months. The combination of a peculiar thermonuclear supernova together with an X-ray flare thus whistle-blows the existence of such moderate-mass black holes. The next generation of wide field space-based instruments should be able to detect such events.Comment: 8 pages, 2 figures, EuroWD0