Dimensional Analysis: Overview and applications to problems of Soil-Structure Interaction

Dimensional Analysis is a long-established tool widely used in many branches of engineering and science. However, applications in geotechnical engineering, and in particular soil-structure interaction (SSI), have barely been explored, in spite of the method's potential to clarify parameter influence and shed light on the range of response regimes. The purpose of this text is twofold: (a) it intends to provide a brief introduction to Dimensional Analysis specifically tailored to geotechnical engineers by carefully choosing illustrative examples, (b) it uses Dimensional Analysis to study the parameter space in soil-building interaction problems, emphasizing modeling choices and using a finite-element model to demonstrate the concept of physical similarity. The suitability of using certain dimensionless parameters over others is discussed based on and their magnitude and sensitivity analysis

Quantum correlations versus Multisimultaneity: an experimental test

Multisimultaneity is a causal model of relativistic quantum physics which assigns a real time ordering to any set of events, much in the spirit of the pilot-wave picture. Contrary to standard quantum mechanics, it predicts a disappearance of the correlations in a Bell-type experiment when both analysers are in relative motion such that, each one in its own inertial reference frame, is first to select the output of the photons. We tested this prediction using acousto-optic modulators as moving beam-splitters and interferometers separated by 55 m. We didn't observe any disappearance of the correlations, thus refuting Multisimultaneity.Comment: 4 pages, 3 figures, RevTex 4 versio

Fast or Frugal, but not both: Decision Heuristics under Time Pressure

Heuristics are simple, yet effective, strategies that people use to make decisions. Because heuristics do not require all available information, they are thought to be easy to implement and to not tax limited cognitive resources, which has led heuristics to be characterized as fast-and-frugal. We question this monolithic conception of heuristics by contrasting the cognitive demands of two popular heuristics, Tallying and Take-the-Best. We contend that heuristics that are frugal in terms of information usage may not always be fast because of the attentional control required to implement this focus in certain contexts. In support of this hypothesis, we find that Take-the-Best, while being more frugal in terms of information usage, is slower to implement and fares worse under time pressure manipulations than Tallying. This effect is then reversed when search costs for Take-the-Best are reduced by changing the format of the stimuli. These findings suggest that heuristics are heterogeneous and should be unpacked according to their cognitive demands to determine the circumstances a heuristic best applies

Presencia del ejército en el desarrollo educativo de las provincias de Loja y el Oriente

Una de las grandes preocupaciones de los países del Tercer Mundo y de América Latina en particular, es el de hacer realidad uno de los deberes primordiales del Estado cual es la EDUCACION, la misma que constituye un derecho para toda la población, un valioso instrumento para mejorar la calidad de la vida y lograr el establecimiento de estructuras sociales más justas e igualitarias. Este propósito educativo tiende a favorecer el proceso de creación de un nuevo procedimiento que permita alcanzar el desarrollo multilateral e integral para las áreas más deprimidas de un Estado. En los últimos años, muchos organismos internacionales como la UNESCO y otros de diverso nivel, junto con los gobiernos de los países menos desarrollados, han realizado sustanciales esfuerzos para ejecutar políticas educativas que se orienten a la consecución de esos fines, particularmente en lo que se refiere a las zonas rurales, donde radica la población más afectada por la deficiente estructuración social de nuestros países. Sin embargo, no es menos cierto que las experiencias acumuladas en este aspecto espacialmente en el Ecuador no han podido solucionar aún los problemas educativos de que adolece la población marginada del campo, muy particularmente la de las provincias de Loja y de la Región Oriental, lo que hace necesario y urgente la búsqueda de nuevas alternativas, acordes con las expectativas de un desarrollo justo y una redención social efectiva para el pueblo ecuatoriano. La Comandancia General del Ejército, consiente de la importancia capital que representa la educación en el desarrollo de nuestro país y del problema que adolece en este campo, ha propuesto un trabajo de Investigación Individual al Instituto de Altos Estudios Nacionales, con el Tema: " LA PRESENCIA DEL EJERCITO EN EL DESARROLLO EDUCATIVO DE LAS PROVINCIAS DE LOJA Y EL ORIENTE" con el criterio de apoyar a la educación como colaboración al desarrollo social de nuestro país, tal cual reza en la Constitución de la República

Propulsion in a viscoelastic fluid

Flagella beating in complex fluids are significantly influenced by viscoelastic stresses. Relevant examples include the ciliary transport of respiratory airway mucus and the motion of spermatozoa in the mucus-filled female reproductive tract. We consider the simplest model of such propulsion and transport in a complex fluid, a waving sheet of small amplitude free to move in a polymeric fluid with a single relaxation time. We show that, compared to self-propulsion in a Newtonian fluid occurring at a velocity U_N, the sheet swims (or transports fluid) with velocity U / U_N = [1+De^2 (eta_s)/(eta) ]/[1+De^2], where eta_s is the viscosity of the Newtonian solvent, eta is the zero-shear-rate viscosity of the polymeric fluid, and De is the Deborah number for the wave motion, product of the wave frequency by the fluid relaxation time. Similar expressions are derived for the rate of work of the sheet and the mechanical efficiency of the motion. These results are shown to be independent of the particular nonlinear constitutive equations chosen for the fluid, and are valid for both waves of tangential and normal motion. The generalization to more than one relaxation time is also provided. In stark contrast with the Newtonian case, these calculations suggest that transport and locomotion in a non-Newtonian fluid can be conveniently tuned without having to modify the waving gait of the sheet but instead by passively modulating the material properties of the liquid.Comment: 21 pages, 1 figur