2,454 research outputs found
Habitat Variation in Vernal Pool Ecosystems on Both Sides of the Strait of Gibraltar
We studied vernal pool (VP) ecosystems along a latitudinal gradient crossing the Strait of Gibraltar in order to determine its role in the distribution of VP plant communities. We analyzed flora, vegetation, physical–chemical water parameters, and climatic data from two vernal pool areas on both the European (Iberian) and African (Moroccan) sides of the Strait. Despite the minor distance between both territories, the pools clearly differed in species composition and ecology. However, they showed a similar vegetation zonation in growth forms, including isoetid, batrachiid, and helophytic vegetation. The distribution of the plant communities was related to nutrient load, temperature, and precipitation. Water nitrate concentration was higher in Morocco, where VPs are characterized by Isoetes velata subsp. adspersa and Ranunculus saniculifolius communities. Iberian VPs had lower water nitrate content, and were characterized by Isoetes velata subsp. velata and Ranunculus peltatus communities. We think this nutrient difference is likely to be caused by the different land management regime on each side of the Strait, with more intensive agriculture in Morocco. Long-term (historical) and present-day (ecological) processes have been proposed to account for the habitat variation in vernal pool ecosystems on both sides of the Strait of Gibraltar
Analytical expressions for the dispersive contributions to the nucleon-nucleus optical potential
Analytical solutions of dispersion relations in the nucleon-nucleus optical model have been found for both volume and surface potentials. For the energy dependence a standard Brown-Rho function has been assumed
for both the volume and surface imaginary contributions multiplied in this later case by a decreasing exponential function. The solutions are valid for any even value of the powers appearing in these functional forms.Junta de AndalucÃa y CICYT FPA2001-0144-C05-03 FPA2001-4960-EUnión Europea KIW-CT-2000-0010
Asset Management System through the design of a Jadex Agent System
In this paper we have designed an agent system using JADEX platform in order to facilitate the asset management of an institution with several types of assets with some unknown similarities, and a high number of operators. Such environment would justify the use of a recommendation system that would provide an useful plan to be applied over an asset generated from previous maintenance operations hold over other assets. Here we provide the full design of such agent system, including the ontology, beliefs, plans, protocols and goals. This design has been implemented within GAIA: an information & asset management solution developed by Altran
Kerker Conditions Upon Lossless, Absorption, and Optical Gain Regimes
The directionality and polarization of light show peculiar properties when
the scattering by a dielectric sphere can be described exclusively by electric
and magnetic dipolar modes. Particularly, when these modes oscillate in-phase
with equal amplitude, at the so-called first Kerker condition, the zero optical
backscattering condition emerges for non-dissipating spheres. However, the role
of absorption and optical gain in the first Kerker condition remains
unexplored. In this work, we demonstrate that either absorption or optical gain
precludes the first Kerker condition and, hence, the absence of backscattered
radiation light, regardless of the size of the particle, incident wavelength,
and incoming polarization. Finally, we derive the necessary prerequisites of
the second Kerker condition of the zero forward light scattering, finding that
optical gain is a compulsory requirement
Integral measurement of the 12C(n, p)12B reaction up to 10 GeV
The integral measurement of the 12C(n, p)12B reaction was performed at the neutron time-offlight facility n TOF at CERN. The total number of 12B nuclei produced per neutron pulse of the n TOF
beam was determined using the activation technique in combination with a time-of-flight technique. The
cross section is integrated over the n TOF neutron energy spectrum from reaction threshold at 13.6 MeV
to 10 GeV. Having been measured up to 1 GeV on basis of the 235U(n, f) reaction, the neutron energy
spectrum above 200 MeV has been re-evaluated due to the recent extension of the cross section reference
for this particular reaction, which is otherwise considered a standard up to 200 MeV. The results from the
dedicated GEANT4 simulations have been used to evaluate the neutron flux from 1 GeV up to 10 GeV. The
experimental results related to the 12C(n, p)12B reaction are compared with the evaluated cross sections
from major libraries and with the predictions of different GEANT4 models, which mostly underestimate
the 12B production. On the contrary, a good reproduction of the integral cross section derived from measurements is obtained with TALYS-1.6 calculations, with optimized parameters.European Atomic Energy Communitys (Euratom) Seventh Framework Programme FP7/2007-2011-CHANDA (No. 605203)Narodowe Centrum Nauki (NCN)-UMO-2012/04/M/ST2/00700Croatian Science Foundation-No. 168
Capital social, metas del milenio y desarrollo local : el caso de la Iniciativa de Carapeguá en Desarrollo, Paraguay
¿Puede lo global y lo local generar una sinergia catalizadora del desarrollo comunitario en forma sostenible? ¿Puede la aplicación de la "caja de herramientas" de la gerencia social fortalecer el capital social, que a su vez impulsará el desarrollo local? ¿Puede la capacitación en gerencia social ser un elemento articulador y catalizador del desarrollo local? El objetivo a corto plazo del programa fue el de fortalecer el capital social local para catalizar una estrategia de desarrollo local sostenible, que mejore las condiciones de vida de la población en forma consistente con los objetivos de desarrollo del milenio. Para evaluar el impacto del programa sobre el capital social, se presentan y analizan las acciones y procesos del programa que pudieron haber impactado sobre los distintos elementos que constituyen el acervo de capital social de una comunidad
Solving Combinatorial Problems with Time Constrains Using Estimation of Distribution Algorithms and Their Application in Video-Tracking Systems
This work was supported in part by Projects CICYT TIN2008-06742-C02-02/TSI, CICYT
TEC2008-06732-C02-02/TEC, SINPROB, CAM MADRINET S-0505 /TIC/0255 and DPS2008-07029-C02-02
Level densities of transitional Sm nuclei
Experimentally determined level densities of the transitional isotopes 148, 149, 150, 152Sm at excitation energies below and around the neutron binding energy are compared with microcanonical calculations based on a Monte Carlo approach to noncollective level densities, folded with a collective enhancement estimated in the frame of the interacting boson model (IBM). The IBM parameters are adjusted so as to reproduce the low-lying discrete levels of both parities, with the exception of the odd-mass nucleus, 149Sm, where complete decoupling of the unpaired neutron from the core is assumed
Sistema de Recuperación de Sincronismo para el modo Wide Swath de ENVISAT
El presente proyecto tiene como objetivo el diseño e implementación del sistema de
recuperación de sincronismo de PRF que será utilizado en la versión aerotransportada
de SABRINA. El objetivo final es que el futuro prototipo sea capaz de adquirir de
forma eficiente la señal SAR recibida. Además, se desea que el sistema pueda trabajar con sistemas que operan en modo ScanSAR. Por ello, el sistema de recuperación de
sincronismo es presentado para los modos WSM (Wide Swath Mode) e IM (Image
Mode) de ENVISAT, sirviendo asà de base para su utilización en otros sistemas
ScanSAR y StripMap, respectivamente
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