Absence of squirt singularities for the multi-phase Muskat problem

In this paper we study the evolution of multiple fluids with different constant densities in porous media. This physical scenario is known as the Muskat and the (multi-phase) Hele-Shaw problems. In this context we prove that the fluids do not develop squirt singularities.Comment: 16 page

The current financial crisis: what should we learn from the great depressions of the Twentieth Century?

Studying the experience of countries that have experienced great depressions during the twentieth century teaches us that massive public interventions in the economy to maintain employment and investment during a financial crisis can, if they distort incentives enough, lead to a great depression.

Nonexistence of self-similar singularities for the 3D incompressible Euler equations

We prove that there exists no self-similar finite time blowing up solution to the 3D incompressible Euler equations. By similar method we also show nonexistence of self-similar blowing up solutions to the divergence-free transport equation in $\Bbb R^n$. This result has direct applications to the density dependent Euler equations, the Boussinesq system, and the quasi-geostrophic equations, for which we also show nonexistence of self-similar blowing up solutions.Comment: This version refines the previous one by relaxing the condition of compact support for the vorticit

Breakdown of smoothness for the Muskat problem

In this paper we show that there exist analytic initial data in the stable regime for the Muskat problem such that the solution turns to the unstable regime and later breaks down i.e. no longer belongs to $C^4$.Comment: 93 pages, 10 figures (6 added

Evaluación de variedades de caña de azúcar (Saccharum spp.) para la producción de panela en linares departamento de Nariño

Con el fin de mejorar la producción de panela, en el municipio de Linares, Nariño (01º 21’ 22.4”Norte y 77º 31’ 77.5”Oeste), se evaluó el comportamiento agronómico y agroindustrial de siete variedades de caña de azúcar. Se empleó un diseño estadístico de bloques completos al azar con siete tratamientos y tres repeticiones. Los resultados mostraron que las variedades CC 84-75, CC 85-92, CC 85-47 y RD 75-11, presentaron bajo volcamiento, las cuales pueden ser consideradas promisorias para la producción de panela. Las seis variedades de caña y el testigo presentaron buen comportamiento fitosanitario ante la presencia de las enfermedades Bipolaris sacchari (mancha de ojo) y Leptosphaeria sacchari (mancha de anillo) y por tanto se clasifica como resistente bajo condiciones naturales de infección. Las seis variedades introducidas mostraron comportamiento similar al testigo en incidencia de daño por el barrenador Diatraea spp. y rendimiento de panela el cual osciló entre 10.77 t.ha-1 y 16.15 t.ha-1 sin diferencias significativas entre tratamientos (p > 0.05)

La rauda del Alcázar de Córdoba

The aims of this study are to review the types of information which can be potentially obtained in the research of the populational dynamic on Xth century in Cordoba, based on an anthropological sample proceeding from an islamic cemetery. Preservation introduces a multitude of confounding factors to give a false appearance to the osteological samples, pointing to the paleopathological aspects as the more conditioned.El objetivo de este estudio es mostrar las diferentes informaciones que pueden ser obtenidas potencialmente en la investigación de la dinámica de poblaciones en el siglo X en Córdoba, basada en una muestra antropológica procedente de una necrópolis islámica. La preservación aporta múltiples factores que enmascaran las muestras osteológicas, con los aspectos paleopatológicos como los más condicionados

Ricci flow, quantum mechanics and gravity

It has been argued that, underlying any given quantum-mechanical model, there exists at least one deterministic system that reproduces, after prequantisation, the given quantum dynamics. For a quantum mechanics with a complex d-dimensional Hilbert space, the Lie group SU(d) represents classical canonical transformations on the projective space CP^{d-1} of quantum states. Let R stand for the Ricci flow of the manifold SU(d-1) down to one point, and let P denote the projection from the Hopf bundle onto its base CP^{d-1}. Then the underlying deterministic model we propose here is the Lie group SU(d), acted on by the operation PR. Finally we comment on some possible consequences that our model may have on a quantum theory of gravity.Comment: 8 page

Neutrino mixing and masses in a left-right model with mirror fermions

In the framework of a left-right model containing mirror fermions with gauge group SU(3)$_{C} \otimes SU(2)_{L} \otimes SU(2)_{R} \otimes U(1)_{Y^\prime}$, we estimate the neutrino masses, which are found to be consistent with their experimental bounds and hierarchy. We evaluate the decay rates of the Lepton Flavor Violation (LFV) processes $\mu \rightarrow e \gamma$, $\tau \rightarrow \mu \gamma$ and $\tau \rightarrow e\gamma$. We obtain upper limits for the flavor-changing branching ratios in agreement with their present experimental bounds. We also estimate the decay rates of heavy Majorana neutrinos in the channels $N \rightarrow W^{\pm} l^{\mp}$, $N \rightarrow Z \nu_{l}$ and $N \rightarrow H \nu_{l}$, which are roughly equal for large values of the heavy neutrino mass. Starting from the most general Majorana neutrino mass matrix, the smallness of active neutrino masses turns out from the interplay of the hierarchy of the involved scales and the double application of seesaw mechanism. An appropriate parameterization on the structure of the neutrino mass matrix imposing a symmetric mixing of electron neutrino with muon and tau neutrinos leads to Tri-bimaximal mixing matrix for light neutrinos.Comment: Accepted by European Physical Journal

Public and private sector wages interactions in a general equilibrium model

This paper develops a dynamic general equilibrium model in which the public and the private sector interact in the labor market. Previous studies that analyze the labor market effects of public sector employment and wages have mostly assumed exogenous rules for public wage and public employment. We show that theories that equalize wages with marginal products in the private sector can rationalize the interaction of public and private sector wages when extended to accommodate a non-trivial government sector/public sector union that endogenously determines public employment and wages. Our model suggests a positive correlation between public and private sector wages. Any increase in tax revenues, coupled with the existence of a positive public-private sector wage gap, makes working in the public sector an attractive option. Thus, a positive neutral productivity shock increases public and private sector wages. More interestingly, even a private-sector specific productivity shock spills-over to the public sector, increasing public wages. These facts lend some support to the wage leading role of the private sector. Nevertheless, at the same time, a positive shock to public sector wages would lead to an increase in private sector wages, via the flow of workers from the private to the public sector. JEL Classification: C32, J30, J51, J52, E62, E63, H50Labor market, public employment, public wages, Trade Unions