Habitada palabra: Claudia Trujillo

Cuando se comienza a estar en la vida, no necesitamos sino tenernos a nosotros mismos. Nada nos lleva a relacionarnos con nadie ni con nada. Vivimos en la condición de quién es nuevo en esa vida, de quién la inicia y que no siente necesidad, al decir de sí mismo, de ese su decirse a sí mismo. Y lo que sabe lo sabe, sin duda, para sí mismo. Y lo que no sabe, no le interesa saberlo. En esa su vida no debe causar inquietud el no saber nada. Es la nada en su intensidad más derribadora. Es lo real que se hace en uno mismo. Cada momento de ello, del comienzo de la vida, es como quién está desnudo y lo sabe. Y siente que está desnudo. No tiene sentido no estarlo y no hace nada por no estarlo. No quiere hacerlo. Nadie le dice, todavía, en ese todavía maravilloso, que tiene que hacerlo. Desnudo se mueve entonces en el comienzo. Aquí no es necesario decir nada a nadie, sino con uno mismo. Esa es la incendiaria inclinación por vivir. Es instalarse como en una maravillosa nada del decir. Decir de la nada. Óscar Jairo González Hernández Profesor Facultad de Comunicación Universidad de Medellín, presenta la obra Habitada Palabra de la poeta Claudia Trujillo, libro editado por la Universidad de Antioquia

Clément Rosset: entre el más acá y el más allá de su muerte

El pensamiento de Clément Ros­set (1939-2018), se nos muestra siempre y en todo momento, como un pensamiento construido y formado desde la perspectiva de la necesidad interior, de la actividad exterior y de la resolución en el deslumbramiento del descubrimiento de lo que buscaba conocer, en la que se mantiene constantemente arrebatado y dominado por la cer­teza y la incertidumbre del pensar. ; Profesor Facultad de Comunicación. Co­municación y Lenguajes Audiovisuales. Uni­versidad de Medellín

A convolve-and-MErge approach for exact computations on high-performance reconfigurable computers

This work presents an approach for accelerating arbitrary-precision arithmetic on high-performance reconfigurable computers (HPRCs). Although faster and smaller, fixed-precision arithmetic has inherent rounding and overflow problems that can cause errors in scientific or engineering applications. This recurring phenomenon is usually referred to as numerical nonrobustness. Therefore, there is an increasing interest in the paradigmof exact computation, based on arbitrary-precision arithmetic. There are a number of libraries and/or languages supporting this paradigm, for example, the GNUmultiprecision (GMP) library. However, the performance of computations is significantly reduced in comparison to that of fixed-precision arithmetic. In order to reduce this performance gap, this paper investigates the acceleration of arbitrary-precision arithmetic on HPRCs. A Convolve-And-MErge approach is proposed, that implements virtual convolution schedules derived from the formal representation of the arbitraryprecision multiplication problem. Additionally, dynamic (nonlinear) pipeline techniques are also exploited in order to achieve speedups ranging from 5x (addition) to 9x (multiplication), while keeping resource usage of the reconfigurable device low, ranging from 11% to 19%

Topology of 2D and 3D Rational Curves

In this paper we present algorithms for computing the topology of planar and space rational curves defined by a parametrization. The algorithms given here work directly with the parametrization of the curve, and do not require to compute or use the implicit equation of the curve (in the case of planar curves) or of any projection (in the case of space curves). Moreover, these algorithms have been implemented in Maple; the examples considered and the timings obtained show good performance skills.Comment: 26 pages, 19 figure

Dehydration accelerates reductions in cerebral blood flow during prolonged exercise in the heat without compromising brain metabolism

Dehydration hastens the decline in cerebral blood flow (CBF) during incremental exercise, while the cerebral metabolic rate for oxygen (CMRO2) is preserved. It remains unknown whether CMRO2 is also maintained during prolonged exercise in the heat and whether an eventual decline in CBF is coupled to fatigue. Two studies were undertaken. In study 1, ten male cyclists cycled in the heat for ~2 h with (control) and without fluid replacement (dehydration) while internal (ICA) and external (ECA) carotid artery blood flow and core and blood temperature were obtained. Arterial and internal jugular venous blood samples were assessed with dehydration to evaluate the CMRO2. In study 2 (8 males), middle cerebral artery blood velocity (MCA Vmean) was measured during prolonged exercise to exhaustion in both dehydrated and euhydrated states. After a rise at the onset of exercise, ICA flow declined to baseline with progressive dehydration (P < 0.05). However, cerebral metabolism remained stable through enhanced oxygen and glucose extraction (P < 0.05). ECA flow increased for one hour but declined prior to exhaustion. Fluid ingestion maintained cerebral and extra-cranial perfusion throughout non-fatiguing exercise. During exhaustive exercise, however, euhydration delayed but did not prevent the decline in cerebral perfusion. In conclusion, during prolonged exercise in the heat dehydration accelerates the decline in CBF without affecting CMRO2 and also restricts extra-cranial perfusion. Thus fatigue is related to reduction in CBF and extra-cranial perfusion rather than in CMRO2.The study was supported by a grant from the Gatorade Sports Science Institute, PepsiCo Inc, USA

Calculation of the energy spectrum of a two-electron spherical quantum dot

We study the energy spectrum of the two-electron spherical parabolic quantum dot using the exact Schroedinger, the Hartree-Fock, and the Kohn-Sham equations. The results obtained by applying the shifted-1/N method are compared with those obtained by using an accurate numerical technique, showing that the relative error is reasonably small, although the first method consistently underestimates the correct values. The approximate ground-state Hartree-Fock and local-density Kohn-Sham energies, estimated using the shifted-1/N method, are compared with accurate numerical self-consistent solutions. We make some perturbative analyses of the exact energy in terms of the confinement strength, and we propose some interpolation formulae. Similar analysis is made for both mean-field approximations and interpolation formulae are also proposed for these exchange-only ground-state cases.Comment: 18 pages, LaTeX, 2 figures-ep

A PGD-based multiscale formulation for non-linear solid mechanics under small deformations

Model reduction techniques have became an attractive and a promising field to be applied in multiscale methods. The main objective of this work is to formulate a multiscale procedure for non-linear problems based on parametrized microscale models. The novelty of this work relies in the implementation of the model reduction technique known as Proper Generalized Decomposition for solving the high dimensional parametrized problem resulting from the microscale model. The multiscale framework here proposed is formulated to non-linear problems, specifically to material non-linearities, where material response is governed by a strain dependent evolution law. Two strategies to deal with this kind of problem under small deformations are detailed in this work. Both strategies based on parametrized microscale models solved by PGD have been applied to a problem with a rate-dependent isotropic damage model. First, a procedure where the problem is solved by uncoupling the equilibrium equation to the state variable expression has been explored. In order, to alleviate the parametrized microscale problem, a second strategy for problems with material non-linearity has been proposed, incorporating a parametrized microscale problem at each macroscale increment (FE-PGD). The basis of those procedures are described and compared, highlighting the solution accuracy and computer time consumption in comparison to a traditional finite element analysis

Rings whose class of projective modules is socle fine

A class C of modules over a unitary ring is said to be socle fine if whenever M, N ∈ C with Soc(M) ∼= Soc(N) then M ∼= N. In this work we characterize certain types of rings by requiring a suitable class of its modules to be socle fine. Then we study socle fine classes of quasi-injective, quasi-projective and quasicontinuous modules which we apply to find socle fine classes in special types of noetherian rings. We also initiate the study of those rings whose class of projective modules is socle fine

A new twist on Lorenz links

Twisted torus links are given by twisting a subset of strands on a closed braid representative of a torus link. T--links are a natural generalization, given by repeated positive twisting. We establish a one-to-one correspondence between positive braid representatives of Lorenz links and T--links, so Lorenz links and T--links coincide. Using this correspondence, we identify over half of the simplest hyperbolic knots as Lorenz knots. We show that both hyperbolic volume and the Mahler measure of Jones polynomials are bounded for infinite collections of hyperbolic Lorenz links. The correspondence provides unexpected symmetries for both Lorenz links and T-links, and establishes many new results for T-links, including new braid index formulas.Comment: This version will be published in J. Topology (2009). 31 pages, 6 figure

Ethiopia : history and legend

Bibliografía: p. 289-290Esta obra ofrece en 16 capítulos y 2 apéndices, una visión global de la antigua y rica historia de Etiopía, desde el surgimiento de la civilización aksumita hasta el reciente desarrollo político. El libro comienza con un capítulo sobre el ascenso de Aksum (Todo comenzó en Aksum), sin dejar de lado las leyendas, como la de la Reina de Saba y el Arca perdida. A continuación, da una visión general sobre el periodo medieval, la historia del Preste Juan y la época de la misión jesuita (Pedro Páez, misionero y constructor). En los siguientes capítulos, la narrativa se centra en el período más moderno, incluido el reinado de Tewodros II (Tewodros, el elegido de Dios), Menelik II (Fundador de la Etiopía moderna) y Hayle Selassie I (El último león de Judá). Luego, en un interludio, el autor analiza la singularidad de la ciudad de Harare, la historia y sociedad de Etiopía. Examina dos importantes episodios de la época contemporánea, la revolución Derg y la guerra etíope-eritrea. También analiza el papel de la religión en el país