Possibility, actuality, and the growth of imagination : the many-worlds approach to quantum physics

Las interpretaciónes de la física cuántica de Everett-DeWitt hablan de una multiplicidad de mundos físicamente coexistenrtes. Éstas imaginativas reacciones a los problemas conceptuales de la mecánica cuántica estándar forman una família de propuestas de "universos múltiples" (PMW en su siglas inglesas) que, sin pleno éxito, han sido tachadas de incoherentes.Everett-DeWitt interpretations of quantum physics speak of a multiplicity of physically coexisting worlds. These imaginative reactions to the conceptual problems of standard quantum mechanics form a family of physicalist "many-worlds" proposals (PMW for short) that have been variously dismissed as "incoherent", so far without full success. A renewed charge by Hilary Putnam now seems to pose deeper trouble for PMW. In a recent paper, he seizes on "Schrödinger's cat" situations to expose how PMW relativization of actuality and basic combinatorics jointly ruin probabilistic talk. Putnam focuses on confirmation and luck. His case against PMW is thought-provoking but also questionable, or so I suggest in this paper. First I argue that, as presented, Putnam's charge doesn't go through. I then consider his argument proper. According to Putnam, experimental DeWittians must count themselves as "lucky" in a seriously incoherent sense. I consider his take on "luck" and deny that defenders of PMW need to so regard themselves. Although extravagant, their position cannot be fruitfully dismissed as incoherent on metascientific grounds. Indeed it attests to the way science rationally helps the imagination to grow

Realism and the Infinitely Faceted World : Intimations from the 1950s

Breaking away from logical-empiricism, in the early 1950s Stephen Toulmin presented empirical theories as maps, thereby opening a fertile line of reflection about background interests and their impact on abstraction in scientific theorizing. A few years later, pointing to the "qualitative infinity of nature," David Bohm denounced what he regarded as counterproductive constraints on the scientific imagination. In realist circles, these two strands of suggestions would be variously supplemented over the following decades with further recognitions of the epistemic merits of partial approximate descriptions and the role of background knowledge and interests in scientific theorizing.Rompiendo con el empirismo lógico, en la década de 1950 Stephen Toulmin presenta como mapas las teorías empíricas, abriendo así una línea fértil de reflexión sobre los intereses que motivan cada teoría y el impacto de dichos intereses en la abstracción en la teorización teórico/científica. Unos años más tarde David Bohm, señalando el "infinito cualitativo de la naturaleza", denunció lo que él consideraba restricciones contraproducentes en la imaginación científica. En los círculos realistas, estas dos visiones serán complementadas de diversas maneras durante las siguientes décadas con reconocimientos de los méritos epistémicos de las descripciones aproximadas parciales y el papel de los intereses y conocimientos previos en la teorización científica

Quasiperiodic graphs at the onset of chaos

We examine the connectivity fluctuations across networks obtained when the horizontal visibility (HV) algorithm is used on trajectories generated by nonlinear circle maps at the quasiperiodic transition to chaos. The resultant HV graph is highly anomalous as the degrees fluctuate at all scales with amplitude that increases with the size of the network. We determine families of Pesin-like identities between entropy growth rates and generalized graph-theoretical Lyapunov exponents. An irrational winding number with pure periodic continued fraction characterizes each family. We illustrate our results for the so-called golden, silver and bronze numbers.Comment: arXiv admin note: text overlap with arXiv:1205.190

The effect of confinement on the deformation of microfluidic drops

We study the deformation of drops squeezed between the floor and ceiling of a microchannel and subjected to a hyperbolic flow. We observe that the maximum deformation of drops depends on both the drop size and the rate of strain of the external flow and can be described with power laws with exponents 2.59 +/- 0.28 and 0.91 +/- 0.05 respectively. We develop a theoretical model to describe the deformation of squeezed drops based on the Darcy approximation for shallow geometries and the use of complex potentials. The model describes the steady-state deformation of the drops as a function of a non-dimensional parameter Ca d^2, where Ca is the capillary number (proportional to the strain rate and the drop size) and d is a confinement parameter equal to the drop size divided by the channel height. For small deformations, the theoretical model predicts a linear relationship between the deformation of drops and this parameter, in good agreement with the experimental observations.Comment: 6 pages, 7 figure

Experimental analysis of 3D cracking in drying soils using ground-penetrating radar

This paper describes the capabilities of a novel technique to investigate crack formation and propagation in drying soils. The technique is a relatively simple, non-destructive indirect technique using a ground-penetrating-radar (GPR) system to detect cracks that form and propagate inside a soil specimen during desiccation. Although GPR devices have been used for multiple applications, their use in soils for the detection of small desiccation cracks has not been demonstrated yet. The experiment and the methodology used to test the accuracy of a small compact commercial GPR device for crack identification are described. The main objective was to identify what type of signals and what crack width and separation between them can be detected using the GPR device. The results indicate that cracks of 1 or 2mm wide can be detected depending on its position and shape, whereas sub-millimeter cracks are undetectable with the currently existing devices in the market. Regardless of this limitation, the GPR method can be useful to find time-related bounds of when the cracks appear, to point at their location and sometimes at the separation between two of them. Detection of cracks with origin at the bottom or within the specimen was accomplished with this system. Distances of 5 cm or more between cracks can be detected and measured, as well, with accuracy.Peer ReviewedPostprint (author's final draft

El comportamiento de la oferta turística

El presente trabajo investigativo se enfoca en determinar el impacto de la actividad turística, como el comportamiento que tiene la oferta turística en nuestro país así como en el departamento de Matagalpa. Reflejamos lo importante que es ofertar el turismo, debido al gran potencial que existe en nuestro país y que no esta siendo ofertado a como se debe por algunas instituciones. Hay Tener en cuenta la importancia que tiene proyectar la inversión hacia el sector turístico para sacar provecho de este y mejorar la economía nacional. El producto turístico es una combinación de elementos y prestaciones que es igual a servicios y productos que le ofrecen al turista nacional y extranjero, y el objetivo de este, es lograr la satisfacción al consumidor y si es posible el regreso de este al lugar. Cuando se habla de oferta turística es hablar del conjunto de bienes y servicios disponibles par satisfacer las necesidades del turista que esta dispuesto a consumir. La oferta del turismo tiene impacto ambiental, social y económico que de una u otra manera influyen en el comportamiento de la economía de nicaragua. El turismo es uno de los sectores que genera grandes divisas al país y es catalogado como una de las principales actividades por lo que se han venido implementando la conformación de los cluster en todos los departamentos, los cuales consisten en la concentración de empresas relacionadas a la misma actividad y con objetivos en comunes para desarrollar el turismo nicaragüens

Ostrogradski approach for the Regge-Teitelboim type cosmology

We present an alternative geometric inspired derivation of the quantum cosmology arising from a brane universe in the context of {\it geodetic gravity}. We set up the Regge-Teitelboim model to describe our universe, and we recover its original dynamics by thinking of such field theory as a second-order derivative theory. We refer to an Ostrogradski Hamiltonian formalism to prepare the system to its quantization. Our analysis highlights the second-order derivative nature of the RT model and the inherited geometrical aspect of the theory. A canonical transformation brings us to the internal physical geometry of the theory and induces its quantization straightforwardly. By using the Dirac canonical quantization method our approach comprises the management of both first- and second-class constraints where the counting of degrees of freedom follows accordingly. At the quantum level our Wheeler-De Witt Wheeler equation agrees with previous results recently found. On these lines, we also comment upon the compatibility of our approach with the Hamiltonian approach proposed by Davidson and coworkers.Comment: 11 pages, 2 figures, accepted for publication in Phys. Rev.

Dietary Diversity in Rural Households: The Case of Indigenous Communities in Sierra Tarahumara, Mexico

Rural populations have a bigger risk of suffering food and nutrition insecurity, mainly, where the indigenous population prevails. The purpose of this research was to analyse the dietary diversity through the Household Dietary Diversity Score (HDDS) in the indigenous communities of Sierra Tarahumara, State of Chihuahua, Mexico. The representative sample is formed of 123 households and it took place in February and March 2015. The households? characteristics were analysed, followed by a discriminant analysis (DA) by steps inclusion to determine which variables determine best the levels of the dietary diversity. The results show that the average HDDS of food consumption was of 6.89 foods. From the twelve food groups defined in this research, most of the respondents consume less than eight food groups (50.41%). The food groups most consumed by the sample of the study were the cereals (100%); legumes or nuts (96.7%); eggs (78.9%); sugar/honey (78%); oils/fats (77.2%). The DA determined that the variables that best explained the dietary diversity were food spending per capita, casual employment, the Prospera program and the marital status of the head of household. The level of low dietary diversity was the best to classify the DA. This research leads us to observe a consumption pattern of a diet based on carbohydrates that can be related to the nutrient deficiency to indicate family malnutrition. This tool can be used as diagnosis for the analysis of interventions on food and nutritional security

Explaining food insecurity among indigenous households of the Sierra Tarahumara in the Mexican state of Chihuahua

Numerous studies have analyzed the factors that determine food security and explored the problem from regional or national points of view. However, there has been less research targeting an understanding of the food security problem at the household level in specific rural locations like indigenous communities. Indigenous groups are recognized as priority groups in Mexico, because they live in a situation of poverty. For this reason, the objective of this research was to investigate the determinants of food insecurity among the indigenous communities of the Sierra Tarahumara in Mexico. We used the Latin American and Caribbean Household Food Security Measurement Scale (ELCSA). This scale is useful for measuring food insecurity levels in households. A questionnaire was administered to 123 households. We employed the method based on Cronbach's alpha to measure internal consistency, which was 0.96. In addition, we estimated the main determinants of household food insecurity using both ordered logit model and binomial logit model. We found that approximately 59.35% of households were living in a situation of severe food insecurity. The two predictive models applied suggest that: i) income is the most important determinant of access to food; ii) increased maize production improves food security; iii) farmers consume their seed stocks in times of food scarcity, and iv) households are food insecure when the householders are in casual employment. Akaike's information criterion and the Bayesian information criterion suggest that the goodness of fit to the data was better for the ordered logit model