Hemeroteca del mes mayo, 2012

Las funciones de la ciencia en el modelo económico cubano

Por • 31 may, 2012 • Category: Internacionales

Cuba ha logrado un balance positivo de su comercio exterior, y eso es un importantísimo logro, después de la desaparición del campo socialista europeo y ante el mantenimiento de la guerra económica de los Estados Unidos contra la Isla. Eso no se puede minimizar, pero también es cierto que ese balance se alcanza a expensas de la exportación de servicios. En la de bienes, sigue siendo negativo. Tal situación puede y debe mejorar con la disminución de importaciones de alimentos —cuyos precios no cesan de crecer—; pero en un país con escasos recursos naturales, y con una población de edad promedio cada vez mayor, y elevada calificación, el balance positivo externo hay que lograrlo con productos de alto valor agregado. Así se recoge en el número 78 de los Lineamientos…, que indica: «Diversificar la estructura de las exportaciones de bienes y servicios, con preferencia las de mayor valor agregado y contenido tecnológico». La ciencia y las producciones de la ciencia, deben ocupar algún día el primer lugar de la economía nacional. Pero partiendo de los escasos recursos, sobre todo de los recursos energéticos que tenemos en nuestro país, tenemos que desarrollar las producciones de la inteligencia, y ese es nuestro lugar en el mundo, no habrá otro.



La trampa del ingreso medio

Por • 31 may, 2012 • Category: Nacionales

En relación a las manufacturas de mano de obra intensiva resulta imposible competir con China



Variation of Mass with Velocity: “Kugeltheorie” or “Relativtheorie”

Por • 30 may, 2012 • Category: Ambiente

This paper deals with four topics: The first subject is Abraham’s spherical electron, Lorentz’s contracted electron and B\”ucherer’s electron. The second topic is Einstein’s 1905 relativity theory of the motion of an electron. Einstein obtained expressions for the longitudinal and transverse masses of the electron using the principle of relativity and that of the constancy of the velocity of light. The third topic is Einstein’s reply to Ehrenfest’s query. Einstein’s above solution appeared to Ehrenfest very similar to Lorentz’s one: a deformed electron. Einstein commented on Ehrenfest’s paper and characterized his work as a theory of principle and reasoned that beyond kinematics, the 1905 heuristic relativity principle could offer new connections between non-kinematical concepts. The final topic is Kaufmann’s experiments. Kaufmann concluded that his measuring procedures were not compatible with the hypothesis posited by Lorentz and Einstein. However, unlike Ehrenfest, he gave the first clear account of the basic theoretical difference between Lorentz’s and Einstein’s views. Finally, B\”ucherer conducted experiments that confirmed Lorentz’s and Einstein’s models; Max Born analyzed the problem of a rigid body and showed the existence of a limited class of rigid motions, and concluded, “The main result was a confirmation of Lorentz’s formula”.



The Missing Memristor: Novel Nanotechnology or rather new Case Study for the Philosophy and Sociology of Science?

Por • 30 may, 2012 • Category: Educacion

In 2008, it was widely announced that the missing memristor, a basic two-terminal electrical circuit element, had finally been discovered. The memristor is the fourth and last such circuit element and thus completes circuit theory. Predicted already in 1971, the eventual discovery of something seemingly so basic needed almost 40 years. However, this discovery is doubted. The predicted memristor has no material memory and is based on magnetic flux, but the discovered devices constitute analogue memory storage that do not involve magnetism. The person who originally proposed the memristor did not reject the discovery but instead changed his mind about what a memristor is. We briefly introduce the history and then carefully memristance and the memristor as such. We discuss its status as a model rather than a device. We discuss the discovered devices, their stability, and how stability relates to the consistency of the theoretical entities. A thought experiment assumes a world without magnetism. Inductors cannot exist there, but memory resistors could still be constructed. On the same grounds as the memristor was historically predicted, an “inductor” could then be predicted. Likely, somebody would also ‘discover’ one. A tentative sociological analysis compares to the flawed detection of gravitational waves but comes to very different conclusions.



A Social Influence Model Based On Circuit Theory

Por • 30 may, 2012 • Category: sociologia

Understanding the behaviors of information propagation is essential for the effective exploitation of social influence in social networks. However, few existing influence models are tractable and efficient for describing the information propagation process, especially when dealing with the difficulty of incorporating the effects of combined influences from multiple nodes. To this end, in this paper, we provide a social influence model that alleviates this obstacle based on electrical circuit theory. This model vastly improves the efficiency of measuring the influence strength between any pair of nodes, and can be used to interpret the real-world influence propagation process in a coherent way. In addition, this circuit theory model provides a natural solution to the social influence maximization problem. When applied to realworld data, the circuit theory model consistently outperforms the state-of-the-art methods and can greatly alleviate the computation burden of the influence maximization problem.



A model structure on categories related to categories of complexes

Por • 30 may, 2012 • Category: Opinion

We prove a theorem of Hinich type on existence of a model structure on a category related by an adjunction to the category of differential graded modules over a graded commutative ring.



Foreword: A Computable Universe, Understanding Computation and Exploring Nature As Computation

Por • 30 may, 2012 • Category: Ciencia y tecnología

I am most honoured to have the privilege to present the Foreword to this fascinating and wonderfully varied collection of contributions, concerning the nature of computation and of its deep connection with the operation of those basic laws, known or yet unknown, governing the universe in which we live. Fundamentally deep questions are indeed being grappled with here, and the fact that we find so many different viewpoints is something to be expected, since, in truth, we know little about the foundational nature and origins of these basic laws, despite the immense precision that we so often find revealed in them. Accordingly, it is not surprising that within the viewpoints expressed here is some unabashed speculation, occasionally bordering on just partially justified guesswork, while elsewhere we find a good deal of precise reasoning, some in the form of rigorous mathematical theorems. Both of these are as should be, for without some inspired guesswork we cannot have new ideas as to where look in order to make genuinely new progress, and without precise mathematical reasoning, no less than in precise observation, we cannot know when we are right — or, more usually, when we are wrong



La propuesta petrolera

Por • 29 may, 2012 • Category: Nacionales

La industria petrolera y por lo tanto el país han gozado de elevados ingresos en divisas (renta) en momentos en que los precios del barril de petróleo se han elevado en forma considerable por razones atinentes al mercado mundial de hidrocarburos. Esa situación ocurrió luego de los primeros años de la administración del presidente Chávez. En esta ocasión, el barril venezolano alcanzó un precio por encima de los 130 dólares, debido a la alta demanda de petróleo por parte de las economías emergentes, en especial las de China e India. Este gobierno ha dispuesto hasta ahora, por esta razón, de más de un billón de dólares, cantidad más que suficiente para haber arrancado la producción de derivadas del petróleo de mucho mayor valor agregado que la simple materia prima que seguimos exportando.



Fiasco latino

Por • 27 may, 2012 • Category: Nacionales

Es posible que muy pronto empecemos a ver una caída de los precios del petróleo



Velocidades de Internet Venezuela vs. El Mundo

Por • 27 may, 2012 • Category: Nacionales

Podemos iniciar diciendo que el promedio de velocidad de descarga de información en Venezuela considerando todos los proveedores de acceso a la Internet es de solo 1.69 Mbps, esto nos ubica en laposición 149 de un total de 176 países del mundo desde los cuales se hacen estas mediciones, siendo solo superados en peor velocidad por países muy atrasados al respecto como Malawi, Bolivia, Irán, Bostwana, Argelia, Bangladesh y Afganistán entre otros muy pocos. Ahora bien, el principal proveedor de acceso a Internet es CANTV Servicios que tiene un promedio de descargas de 0,71 Mbps lo que nos ubica (para la mayoría de los Venezolanos) en la muy penosa posición 175 de 176 países!!!.