782 research outputs found
Situación de familias productoras de papa en la sierra central del Ecuador: Linea de base productiva del Proyecto IssAndes.
Livestock rational use of Anaga Rural Park. Preliminary results
Anaga Rural Park is a natural protected space that is situated in the northeast of Tenerife isle in Canary Islands. With a 14.224 hectares, it’s characterised by high ecosystems diversity, debt to high incline that condition the coexistence of different ecological floors. This situation has determined the uses types of the local resources and the grazing. In this way, the study in the Anaga Rural Park, try to design specific strategy for the rational use of the natural resources in the zone. The methodology used is based on individuals interwievs and geographic information processing, with purpose to define the average stocking rate, annual distribution of stocking rate and animal production systems characteristics in Anaga Rural Park. After to analyse the secondary information, the interwievs realised and the direct observations of the productions systems, we have obtained enough data to locate the zone breed reality of the zone a make and unreliable outline of the production systems in Anaga.El Parque Rural de Anaga es un espacio natural protegido que se encuentra en el noreste de la Isla de Tenerife, en las Islas Canarias. Con unas dimensiones de 14.000 ha, se caracteriza por una alta diversidad de ecosistemas debido a las altas pendientes que condicionan la existencia de diferentes pisos ecológicos. Esto ha determinado las formas de aprovechamiento de los recursos locales en general y del pastoreo en particular. En este sentido, el estudio en el Parque Rural Anaga, trata de diseñar estrategias concretas para el uso racional de los recursos naturales en la zona. La metodología utilizada se basa en las entrevistas individuales y el tratamiento de información geográfica, con el fin de definir la Carga ganadera promedio, la distribución anual de la Carga ganadera y las características de los sistemas de producción animal en el Parque Rural de Anaga. Tras el análisis de la información secundaria, las entrevistas realizadas y la observación directa de los sistemas de producción, se han obtenido suficientes datos como para ubicarnos en la realidad ganadera de la zona y por tanto hacer un esbozo fiable de la situación de los sistemas de producción en Anaga
Livestock use research in canary protected areas. Methodology
Rural Parks are protected natural space included in the Protected Spaces Canary Law. Rural Park condition obliges to planning sustentable development, where the productivity and profitability complement with the sustentability, stability and equity. Anaga is situated in the Tenerife Isle northeast. With surface of 14.000 ha, is characterised by the high ecosystem diversity. Valle Gran Rey is situated in La Gomera Isle southeast. With surface approximately of 2.000 ha, is characterised by the presence of high productivity potential tableland. The study final result is strategy planning to adjust between livestock resources use and those resources potential with economical and ecological guidelines. Methodology is based on meticulous interview to farmers of each Park, to determine the Average Stocking Rate, its annual distribution and classification of production systems. Stoking Rate calculate is realised by livestock needs determination and supplementation determination, combined with treatment of geographical information to study of grazing zones. By unpredictable cuts, exclusion squares, transects and forage analysis is determined the Charge Capacity.Los Parques Rurales son espacios naturales protegidos recogidos en la Ley Canaria de Espacios Protegidos. La condición de Parque Rural obliga a plantear el desarrollo de forma sostenible, donde la productividad y rentabilidad se complementen con la sustentabilidad, estabilidad y equidad. Anaga está situado en el nordeste de la Isla de Tenerife. Con una superficie de aproximadamente 14.000 ha, se caracteriza por la alta diversidad de ecosistemas. Valle Gran Rey está situado en el suroeste de la Isla de la Gomera. Con una superficie aproximada de 2.000 ha, se caracteriza por la presencia de mesetas de alto potencial productivo. El resultado final del estudio es la definición de estrategias para el ajuste entre el uso de los recursos ganaderos y las posibilidades de dichos recursos con criterios de carácter económico y de carácter ecológico. La metodología se basa en la entrevista minuciosa de los ganaderos de cada uno de los Parques, haciendo hincapié en aquellos que realizan pastoreo, con el fin de determinar la carga ganadera promedio, su distribución anual y la caracterización de los sistemas de producción. El cálculo de la Carga ganadera se realiza mediante la determinación de las necesidades animales y la suplementación aportada, combinado con el tratamiento de información geográfica para el estudio de las zonas de pastoreo. Mediante la realización de cortes aleatorios, cuadros de exclusión, transectos y posterior analítica de muestras de plantas forrajeras, se determina la Capacidad de Carga ganadera
The Suaineadh Project : a stepping stone towards the deployment of large flexible structures in space
The Suaineadh project aims at testing the controlled deployment and stabilization of space web. The deployment system is based on a simple yet ingenious control of the centrifugal force that will pull each of the four daughters sections apart. The four daughters are attached onto the four corners of a square web, and will be released from their initial stowed configuration attached to a central hub. Enclosed in the central hub is a specifically designed spinning reaction wheel that controls the rotational speed with a closed loop control fed by measurements from an onboard inertial measurement sensor. Five other such sensors located within the web and central hub provide information on the surface curvature of the web, and progression of the deployment. Suaineadh is currently at an advanced stage of development: all the components are manufactured with the subsystems integrated and are presently awaiting full integration and testing. This paper will present the current status of the Suaineadh project and the results of the most recent set of tests. In particular, the paper will cover the overall mechanical design of the system, the electrical and sensor assemblies, the communication and power systems and the spinning wheel with its control system
Infinitesimal and local convexity of a hypersurface in a semi-Riemannian manifold
Given a Riemannian manifold M and a hypersurface H in M, it is well known
that infinitesimal convexity on a neighborhood of a point in H implies local
convexity. We show in this note that the same result holds in a semi-Riemannian
manifold. We make some remarks for the case when only timelike, null or
spacelike geodesics are involved. The notion of geometric convexity is also
reviewed and some applications to geodesic connectedness of an open subset of a
Lorentzian manifold are given.Comment: 14 pages, AMSLaTex, 2 figures. v2: typos fixed, added one reference
and several comments, statement of last proposition correcte
Nuclear envelope defects cause stem cell dysfunction in premature-aging mice
Nuclear lamina alterations occur in physiological aging and in premature aging syndromes. Because aging is also associated with abnormal stem cell homeostasis, we hypothesize that nuclear envelope alterations could have an important impact on stem cell compartments. To evaluate this hypothesis, we examined the number and functional competence of stem cells in Zmpste24-null progeroid mice, which exhibit nuclear lamina defects. We show that Zmpste24 deficiency causes an alteration in the number and proliferative capacity of epidermal stem cells. These changes are associated with an aberrant nuclear architecture of bulge cells and an increase in apoptosis of their supporting cells in the hair bulb region. These alterations are rescued in Zmpste24−/−Lmna+/− mutant mice, which do not manifest progeroid symptoms. We also report that molecular signaling pathways implicated in the regulation of stem cell behavior, such as Wnt and microphthalmia transcription factor, are altered in Zmpste24−/− mice. These findings establish a link between age-related nuclear envelope defects and stem cell dysfunction
Ansiedad escolar infantojuvenil: una revisión de autoinformes
School anxiety is a set of cognitive, motor and psychophysiological responses emitted by a person in school situations that are perceived as a threat. The research objectives of this study were two. The first one was to describe school anxiety self-reports that have been elaborated and/or validated between 2005 and 2015: School Anxiety Inventory, School Anxiety Inventory-Short Version, Children’s Anxiety in Math Scale, and Test Anxiety Inventory for Children and Adolescents. The second aim was to analyze the reliability (internal consistency and temporal stability) and validity (factorial structure) of the inventories and the scale mentioned above. Results suggest that the psychometric properties of these instruments are suitable. Therefore, these can be used by clinical and educational professionals to assess the school anxiety of children and adolescents.La ansiedad escolar es el conjunto de reacciones cognitivas, motoras y psicofisiolóficas emitidas por una persona ante situaciones del ámbito escolar que son percibidas como una amenaza. Los objetivos de investigación de este trabajo fueron dos. El primero de ellos fue describir los autoinformes de ansiedad escolar que han sido elaborados y/o validados entre el año 2005 y el 2015: Inventario de Ansiedad Escolar, School Anxiety Inventory-Short Version, Children’s Anxiety in Math Scale y Test Anxiety Inventory for Children and Adolescents. El segundo propósito consistió en analizar la fiabilidad (consistencia interna y estabilidad temporal) y validez (estructura factorial) de los inventarios y de la escala mencionados antes. Los resultados sugieren que las propiedades psicométricas de estos instrumentos son adecuadas. Por tanto, pueden ser usados por profesionales clínicos y educativos para evaluar la ansiedad escolar de niños y adolescentes
Excited-state calculations with quantum Monte Carlo
Quantum Monte Carlo methods are first-principle approaches that approximately
solve the Schr\"odinger equation stochastically. As compared to traditional
quantum chemistry methods, they offer important advantages such as the ability
to handle a large variety of many-body wave functions, the favorable scaling
with the number of particles, and the intrinsic parallelism of the algorithms
which are particularly suitable to modern massively parallel computers. In this
chapter, we focus on the two quantum Monte Carlo approaches most widely used
for electronic structure problems, namely, the variational and diffusion Monte
Carlo methods. We give particular attention to the recent progress in the
techniques for the optimization of the wave function, a challenging and
important step to achieve accurate results in both the ground and the excited
state. We conclude with an overview of the current status of excited-state
calculations for molecular systems, demonstrating the potential of quantum
Monte Carlo methods in this field of applications
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