Fundamento geométrico y cinemático de la modelización teórica y experimental de deformaciones no-coaxiales

La combinación de dos componentes longitudinales en condiciones de no cambio de área, con un componente de cizalla paralelo a la dirección del componente de extensión, permite generar un espectro continuo de tipos de deformación entre la cizalla pura y la cizalla simple. El grado de no coaxialidad o la vorticidad se pueden definir por el ángulo que forman entre si las lineas de no rotación. La aplicación de sucesivos incrementos idénticos, mantiene constante la orientación de las lineas de no rotación. Sobre este principio se plantean dos vias de investigación en el campo de la génesis de estructuras de deformación dúctil en regimenes no coaxiales: la modelización analógicautilizandomateriaies artificiaies y la modelización matemática. Las propiedades de las lineas materiales de no rotación, son utilizadas vara diseñar una célula de deformación ex~erimental que cubra todo el espectro. Adicionalmente se presentan dos ejemplos de modelización teórica que muestran la influencia del grado de coaxialidad en la asimetria y orientación de pliegues.Combination of both longitudinal components with a shear component parallel to the direction of the longitudinal extension component leads to a continuum spectrum with pure and simple shear as end members. The degree of non coaxiality or the vorticity can be specified by means of the angle formed by lines undergoing no rotation. The application of successive identical strain increments, keeps uncbanged the orientation of the lines of no rotation after the first increment. On this basis two approaches are presented in order to enhance understanding of the formation of ductile structures under non coaxial strain regimes: experimental modelling using analogue materials and deformation stage, which should cover the whole spectrum between pure and simple shear. Additionally, by means of two examples of mathematical modelling it is shown how the non coaxiality controls fold asymmetry and orientation

Fluctuations of the correlation dimension at metal-insulator transitions

We investigate numerically the inverse participation ratio, $P_2$, of the 3D Anderson model and of the power-law random banded matrix (PRBM) model at criticality. We found that the variance of $\ln P_2$ scales with system size $L$ as $\sigma^2(L)=\sigma^2(\infty)-A L^{-D_2/2d}$, being $D_2$ the correlation dimension and $d$ the system dimension. Therefore the concept of a correlation dimension is well defined in the two models considered. The 3D Anderson transition and the PRBM transition for $b=0.3$ (see the text for the definition of $b$) are fairly similar with respect to all critical magnitudes studied.Comment: RevTex, 5 pages, 4 eps figures, to be published in Phys. Rev. Let

Variación en la contaminación por virus de una semilla de papa sembrada en tres zonas diferentes.

En el Laboratorio de Virología del Centro Nacional de Investigaciones Agropecuarias Tibaitatá, del ICA y en el campo, se sembraron semillas de un origen común y tres meses después se tomaron muestras de hojas y tubérculos de papa variedad Parda Pastusa en tres lotes en los municipios de Suesca, Usme y Mosquera, con diferente altura sobre el nivel del mar. El propósito era conocer la evolución de una semilla homogenea en la infección por tres virus de la papa (PVX, PVY y PLRV). Para determinar los porcentajes de infección por PVX se efectuaron inoculaciones mecánicas sobre Gomphrena globosa L. y reacciones serológicas por el método de latex sensibilizado. En el caso de PVY, las inoculaciones mecánicas se hicieron en Solanum demissum A-6 y Physalis floridana Ryadb, igualmente se efectuaron reacciones serológicas, utilizando látex sensibilizado con anticuerpos específicos para PVY. Para detectar PLRV se utilizó el método de coloración de la calosa con una solución de resorcina azul. La técnica serológica empleada para detectar PVX y PVY demostró alta sensibilidad y sus resultados presentan la asociación de los virus PVX y PVY con incidencia de 43 y 52 por ciento en las fincas de Suesca, 43 y 50 por ciento en Tibaitatá y muy baja en la finca de Usme con 32 y 36 por ciento. Con el método histológico de diagnóstico para el PLRV se encontró que la finca de Tibaitatá tiene una infección de 79 por ciento y las fincas de Suesca y Usme la infección es del 65 por cientoPapa-Solanum tuberosumMaestría en CienciasMaestrí

Health-related quality of life in stroke patients questionnaire, short version (HRQOLISP-40): validation for its use in Colombia

Abstract Background: The health-related quality of life in stroke patients (HRQOLISP-40, short version) survey was developed in Nigeria and constitutes a 40-item, multidimensional, self-administrated questionnaire. We assessed the validity and reliability of the HRQOLISP-40 Spanish version for stroke patients in Colombia. Methods: The analysis included factor analysis, confirmatory factor analysis, Rasch analysis, convergent validity, internal consistency (261 stroke patients), test-retest reliability (73 patients assessed at two different times) and sensitivity to change (46 patients assessed before and after a rehabilitation intervention). Results: We found an 8-domain structure. None of the items had a significant impact on the global alpha value in order to be removed. Lin ’ s concordance correlation coefficient indicated test-retest reliability (Rho IC: 0.76 to 0.95), suggesting an adequate stability of the instrument. Regarding sensitivity to change differences, they were only significant in the psychological and eco-social domains ( p <0.05). When comparing SF-36 with HRQOLISP-40, all the correlation coefficients values were significantly different from zero, except those related to vitality. The highest scores were found in the physical and physical functioning domains, with a value of 0.722. Conclusions: The HRQOLISP-40 scale is valid and reliable for assessing patients ’ quality of life after a stroke. Validating quality of life assessment instruments is necessary in order to improve the effectiveness of rehabilitation programs for Colombian stroke patients

Chromatin immunoprecipitation improvements for the processing of small frozen pieces of adipose tissue.

Chromatin immunoprecipitation (ChIP) has gained importance to identify links between the genome and the proteome. Adipose tissue has emerged as an active tissue, which secretes a wide range of molecules that have been related to metabolic and obesity-related disorders, such as diabetes, cardiovascular failure, metabolic syndrome, or cancer. In turn, epigenetics has raised the importance in discerning the possible relationship between metabolic disorders, lifestyle and environment. However, ChIP application in human adipose tissue is limited by several factors, such as sample size, frozen sample availability, high lipid content and cellular composition of the tissue. Here, we optimize the standard protocol of ChIP for small pieces of frozen human adipose tissue. In addition, we test ChIP for the histone mark H3K4m3, which is related to active promoters, and validate the performance of the ChIP by analyzing gene promoters for factors usually studied in adipose tissue using qPCR. Our improvements result in a higher performance in chromatin shearing and DNA recovery of adipocytes from the tissue, which may be useful for ChIP-qPCR or ChIP-seq analysis

New Results for Diffusion in Lorentz Lattice Gas Cellular Automata

New calculations to over ten million time steps have revealed a more complex diffusive behavior than previously reported, of a point particle on a square and triangular lattice randomly occupied by mirror or rotator scatterers. For the square lattice fully occupied by mirrors where extended closed particle orbits occur, anomalous diffusion was still found. However, for a not fully occupied lattice the super diffusion, first noticed by Owczarek and Prellberg for a particular concentration, obtains for all concentrations. For the square lattice occupied by rotators and the triangular lattice occupied by mirrors or rotators, an absence of diffusion (trapping) was found for all concentrations, except on critical lines, where anomalous diffusion (extended closed orbits) occurs and hyperscaling holds for all closed orbits with {\em universal} exponents ${\displaystyle{d_f = \frac{7}{4}}}$ and ${\displaystyle{\tau = \frac{15}{7}}}$. Only one point on these critical lines can be related to a corresponding percolation problem. The questions arise therefore whether the other critical points can be mapped onto a new percolation-like problem, and of the dynamical significance of hyperscaling.Comment: 52 pages, including 18 figures on the last 22 pages, email: [email protected]

Media Aesthetics: Two Examples in the Spanish Art

Este artículo descubre una estética basada en la intervención de las máquinas en los procedimientos creativos del arte. El estudio profundiza en una estética del maquinismo desde la reflexión filosófica, que abarca desde la incursión de las tecnologías ópticas (fotografía, cinematografía) a las tecnologías electrónicas (videografía, computer graphics, redes). La investigación aporta nuevas luces sobre la noción del Media Art. Los medios han abierto a los artistas las posibilidades del laboratorio de experimentación estética entre arte, ciencia e innovación tecnológica. En este sentido, el texto demuestra como la nueva creatividad mediática ensaya formas más representativas del pensamiento posmoderno. Para una mejor ejemplaridad de la cuestión planteada, el artículo ha analizado brevemente las obras de dos artistas españoles representativos de momentos distintos. En el primer ejemplo, se expone el comienzo de un incipiente Arte de Medios en la cavilaciones tecnológicas y místicas de José Val del Omar. En el segundo ejemplo, se muestra&nbsp; la evolución contemporánea en el ensayo con Internet de Antoni Muntadas. &nbsp;This article unveils an aesthetic based on the intervention of machinery into creative art procedures. The study goes deeply into a machine-related aesthetic from philosophic reflections, which range from the incursions of, firstly, optical technologies (photography, cinematography) and then electronic technologies (videograph, computer graphics, networks). The research throws new light on the notion of Media Art. The media have opened up to artists the possibilities of the laboratory for aesthetic experimentation and the innovative inter-relationship of art, science, and technology.&nbsp; In this sense, the text demonstrates how new media creativity experiments with forms more representative of postmodern thinking.&nbsp; For the purposes of a better exemplification of the question raised, this article has briefly analysed the works of two Spanish artists, representative of the two different phases. The first example opens with the commencement of an incipient Media Art in the technological and mystical ruminations of José Val del Omar. In the second example, the contemporary evolution into internet experimentation of Antoni Muntadas is demonstrated

Holocene paleo-earthquakes recorded at the transfer zone of two majorfaults: the Pastores and Venta de Bravo fault (Trans-Mexican Volcanic Belt).

We present evidence of fi ve late Holocene earthquake ruptures observed at two paleoseismological trenches in the Laguna Bañí sag pond (Trans-Mexican Volcanic Belt, central Mexico). The trenches exposed two fault branches of the western termination of the Pastores fault, one of the major fault systems within the central Trans-Mexican Volcanic Belt. The site was studied by combining geomorphological and structural approaches, volcanic mapping, ground-penetrating radar, and paleoseismological analysis. The study revealed that coseismic surface rupture was noncharacteristic, and that the exposed fault branches had not always moved simultaneously. The fault tip has ruptured at least 5 times within the past 4 k.y., and the rupture events followed and preceded the deposition of an ignimbrite. The close temporal relationship of the seismic rupture with the volcanic activity of the area could be the result of volcanism triggered by faulting and its associated seismicity. The relatively high recurrence of seismic events (1.1 2.6 k.y.) and the noncharacteristic fault behavior observed at this tip of the Pastores fault suggest that the fault might have been active as a primary fault rupturing along segments of variable length or depth, and/or that the fault ruptured eventually as a secondary fault. The secondary ruptures would likely be related to earthquakes produced at major neighboring faults such as the Acambay fault, which moved during the 1912 Acambay earthquake, or the Venta de Bravo fault. A relatively large slip rate estimated for this fault branch (0.23 0.37 mm/yr) leads us to contemplate the possible connection at depth between the Pastores and the Venta de Bravo faults, increasing the maximum expected magnitude for central Mexico

Localized to extended states transition for two interacting particles in a two-dimensional random potential

We show by a numerical procedure that a short-range interaction $u$ induces extended two-particle states in a two-dimensional random potential. Our procedure treats the interaction as a perturbation and solve Dyson's equation exactly in the subspace of doubly occupied sites. We consider long bars of several widths and extract the macroscopic localization and correlation lengths by an scaling analysis of the renormalized decay length of the bars. For $u=1$, the critical disorder found is $W_{\rm c}=9.3\pm 0.2$, and the critical exponent $\nu=2.4\pm 0.5$. For two non-interacting particles we do not find any transition and the localization length is roughly half the one-particle value, as expected.Comment: 4 two-column pages, 4 eps figures, Revtex, to be published in Europhys. Let