The computational complexity of the Chow form

We present a bounded probability algorithm for the computation of the Chow forms of the equidimensional components of an algebraic variety. Its complexity is polynomial in the length and in the geometric degree of the input equation system defining the variety. In particular, it provides an alternative algorithm for the equidimensional decomposition of a variety. As an application we obtain an algorithm for the computation of a subclass of sparse resultants, whose complexity is polynomial in the dimension and the volume of the input set of exponents. As a further application, we derive an algorithm for the computation of the (unique) solution of a generic over-determined equation system.Comment: 60 pages, Latex2

A new convergent algorithm to approximate potentials from fixed angle scattering data

We introduce a new iterative method to recover a real compact supported potential of the Schr\"odinger operator from their fixed angle scattering data. The method combines a fixed point argument with a suitable approximation of the resolvent of the Schr\"odinger operator by partial sums associated to its Born series. Convergence is established for potentials with small norm in certain Sobolev spaces. As an application we show some numerical experiments that illustrate this convergence.Comment: 25 pages, 6 figure

Local Government, Taxes, and Guns: Successful Policy Innovation in Three Colombian Cities

This paper evaluates transformative policy innovations with respect to security and taxation in the three main Colombian cities: Bogotá, Medellín, and Cali. In the first two, such policies were associated with huge success. Elsewhere we (Gutiérrez et al. 2009) have tagged these transformation processes as ‘urban/metropolitan miracles’. The term comes from the fact that both common citizens and pundits considered these to be extremely unlikely, that they were fast, and that they were large-scale. We argue, that the success of Bogotá and Medellín was the result of a set of institutional underpinnings basically related to the 1991 constitution; the opening of a window of opportunity for new political actors; and, as a result, the formation of a new government coalition and ‘governance formula’. Anti-particularism was a language related to political demands— linked organically with the pro-1991 constitution movement—which became effective .../urban security, state building, public policies

Using weibull mixture distributions to model heterogeneous survival data

In this article we use Bayesian methods to fit a Weibull mixture model with an unknown number of components to possibly right censored survival data. This is done using the recently developed, birth-death MCMC algorithm. We also show how to estimate the survivor function and the expected hazard rate from the MCMA output

División de la opinión pública española sobre las estrategias sostenibles del agua. Metodología EASW para la acción consensuada

Conflicts and devided opinion over the water strategies have sharpened in Spain during the years 2000-2001, in which the new National Plan on Water was drawn up by the Government. The main solution launched by the Government, in order to cope with increasing water consumption in the long term, is a large transfer of water from the northern region to southern and eastern regions of the country. Groups of experts and community based associations consider this strategy scarcely satisfactory as a technical and social solution for water. Social actors, who are active or passively involved in the decision-making process concerning the future of water resources, give different reasons for their support or rejection of that plan. This article analyzes the arguments expressed by the different social sectors, i.e., the public administration; the private business and enterprises, the scientific and technological sector, and the community based organizations. With the information they provide, we try to built the structural problematic regarding water sustainability of the coming years. Basically the problematics consist in the following: wether solution is through massive public spending on water transfer, considering that the cost of water will be liberalized in the coming years, and will habe to be paid for by regions and citizens; or throught the inmediate involvement of general population in reducing consumption and in maximising profit from available water, by means of the new environmental technologies.Los conflictos y división de opiniones sobre las estrategias del agua en España se han agudizado en os años 2000-2001 con motivo del nuevo Plan idrológico Nacional, elaborado por el Gobierno, que a establecido como rincipal solución, frente al aumento del consumo a largo plazo, un trasvase asivo de agua de las regiones del Norte a las regiones del Sur y Este del territorio acional. Esta strategia se considera poco satisfactoria como solución écnica y social para el agua, por parte de rupos de expertos y de asociaciones iudadanas os actores sociales, protagonistas implicados por ctiva o por pasiva en el roceso de toma de decisiones sobre el futuro del agua, alegan distintas razones para posicionarse a favor o en contra de este plan. En este artículo se analizan los argumentos comunicados por distintos sectores sociales: el sector público o administración del Estado; el sector privado-empresarial, el sector técnico-científico y el sector asociativo-ciudadano. Con la información que ellos aportan se construye la problemática estructural que se perfila en torno a la sostenibilidad del agua en los próximos años. Básicamente la problemática radica en: si solucionar el agua desde un masivo gasto público, cuando en cinco años se va a liberalizar el agua y repercutir los costes a regiones y ciudadanos, o solucionar el agua implicando a la población «desde ya» en reducir su consumo y aprovechar el agua impulsando las nuevas tecnologías medioambientales. Ante el carácter, social y tecnológicamente, insostenible del escenario tendencial marcado por el PHN para el agua en España, se recomienda implicar a las entidades ciudadanas en la gestión consorciada de los fondos destinados a campañas de sensibilización para el ahorro de agua y la incorporación de nuevas tecnologías medioambientales. La metodología que se recomienda aplicar tanto al diseño de las campañas de sensibilización, como para la sensibilización en sí es el Escenario Workshop EASW con observación del seguimiento

Informative Path Planning for Active Field Mapping under Localization Uncertainty

Information gathering algorithms play a key role in unlocking the potential of robots for efficient data collection in a wide range of applications. However, most existing strategies neglect the fundamental problem of the robot pose uncertainty, which is an implicit requirement for creating robust, high-quality maps. To address this issue, we introduce an informative planning framework for active mapping that explicitly accounts for the pose uncertainty in both the mapping and planning tasks. Our strategy exploits a Gaussian Process (GP) model to capture a target environmental field given the uncertainty on its inputs. For planning, we formulate a new utility function that couples the localization and field mapping objectives in GP-based mapping scenarios in a principled way, without relying on any manually tuned parameters. Extensive simulations show that our approach outperforms existing strategies, with reductions in mean pose uncertainty and map error. We also present a proof of concept in an indoor temperature mapping scenario.Comment: 8 pages, 7 figures, submission (revised) to Robotics & Automation Letters (and IEEE International Conference on Robotics and Automation

Mental Health Services in Mexico

The history of mental health services in Mexico is traced from the time of the Spanish conquest to modern times. The present structure of mental health services is outlined as it relates to the overall social services and health\care system in Mexico. Inpatient, aftercare, partial hospitalization, and outpatient service are outlined and described. Levels of service and distribution of facilities and staff by region are given. Methods of intervention are described from traditional healers, to highly specialized modern psychiatry, to innovative community self-management programs. Key issues in the future are financial resources, distribution of services and staff, and ways to optimally use human resources

Listeriosis

El género Listeria está formado por bacilos grampositivos, no encapsulados ni esporulados y anerobios facultativos. Actualmente comprende diez especies: Listeria monocytogenes, Listeria ivanovii, L. grayi (murrayi), L. innocua, L. marthii, L. rocourtiae, L. seeligeri, L. welshimeri, L. fleischmanni y L. weihenstephanensis. Desde el punto de vista de la seguridad alimentaria es de interés la especie L. monocytogenes, patógena en humanos y animales, mientras que L. ivanovii es patógena en animales y raramente en humanos. Si bien la presencia de factores de virulencia varía con las cepas, a falta de métodos de carácter rutinario para diferenciar entre las cepas de mayor y menor virulencia, todas las cepas de L. monocytogenes son consideradas potencialmente patógenas (EFSA, 2007). L. monocytogenes es un patógeno intracelular, capaz de infectar un amplio tipo de células (epiteliales, endoteliales, hepáticas, fibroblastos, fagocitos), y de atravesar la barrera intestinal, placentaria y hematoencefálica tanto en humanos como en animales (Rahimi et al., 2014).Publishe