110 research outputs found
Composite Boson Mapping for Lattice Boson Systems
We present a canonical mapping transforming physical boson operators into
quadratic products of cluster composite bosons that preserves matrix elements
of operators when a physical constraint is enforced. We map the 2D lattice
Bose-Hubbard Hamiltonian into composite bosons and solve it at mean
field. The resulting Mott insulator-superfluid phase diagram reproduces well
Quantum Monte Carlo results. The Higgs boson behavior along the particle-hole
symmetry line is unraveled and in remarkable agreement with experiment. Results
for the properties of the ground and excited states are competitive with other
state-of-the-art approaches, but at a fraction of their computational cost. The
composite boson mapping here introduced can be readily applied to frustrated
many-body systems where most methodologies face significant hurdles.Comment: 8 pages, 4 figure
Composite fermion-boson mapping for fermionic lattice models
We present a mapping of elementary fermion operators onto a quadratic form of
composite fermionic and bosonic operators. The mapping is an exact isomorphism
as long as the physical constraint of one composite particle per cluster is
satisfied. This condition is treated on average in a composite particle
mean-field approach, which consists of an ansatz that decouples the composite
fermionic and bosonic sectors. The theory is tested on the one- and
two-dimensional Hubbard models. Using a Bogoliubov determinant for the
composite fermions and either a coherent or Bogoliubov state for the bosons, we
obtain a simple and accurate procedure for treating the Mott insulating phase
of the Hubbard model with mean-field computational cost
Estudio mineralógico, textural y físico-mecánico de morteros de cal hidráulica curados en distintas condiciones de humedad relativa
This work focuses on the chemical-mineralogical, textural and physical-mechanical properties of hydraulic lime mortars made with siliceous and calcareous aggregate. Mortars were cured at 60% and 90% of relative humidity, so as to assess the variability of mortar petrophysical properties in the hardened state due to the moisture conditions. The final aim was to determine the most adequate moisture conditions to be maintained during application and hardening of hydraulic mortars intended for repair interventions. We found out that using a calcareous aggregate and curing mortar at 90% of relative humidity give place to better textural and mechanical properties. However, these characteristics mostly depend on the maximum size of the aggregate grains, which should be smaller than 6 mm, in order to avoid the occurrence of mechanical discontinuities in the mortar.En este trabajo se han estudiado las propiedades químico-mineralógicas, texturales y físico-mecánicas de morteros de cal hidráulica elaborados con áridos silíceo y calcítico. Estos morteros se han curado al 60% y 90% de humedad relativa, con el fin de evaluar las eventuales diferencias en las propiedades petrofísicas de los morteros una vez endurecidos y así establecer cuál de los dos ambientes es recomendable durante la aplicación y fraguado de morteros de cal hidráulica destinados a obras de restauración. Se ha encontrado que el uso de un árido de composición calcítica y el curado al 90% de humedad relativa dan lugar a morteros hidráulicos con mejores características texturales y propiedades mecánicas. De todas formas, estas características dependen principalmente del tamaño máximo del árido empleado, que debería ser inferior a 6 mm para evitar discontinuidades mecánicas en el mortero
Estudio mineralógico, textural y físico-mecánico de morteros de cal hidráulica curados en distintas condiciones de humedad relativa
This work focuses on the chemical-mineralogical, textural and physical-mechanical properties of hydraulic lime mortars made with siliceous and calcareous aggregate. Mortars were cured at 60% and 90% of relative humidity, so as to assess the variability of mortar petrophysical properties in the hardened state due to the moisture conditions. The final aim was to determine the most adequate moisture conditions to be maintained during application and hardening of hydraulic mortars intended for repair interventions. We found out that using a calcareous aggregate and curing mortar at 90% of relative humidity give place to better textural and mechanical properties. However, these characteristics mostly depend on the maximum size of the aggregate grains, which should be smaller than 6 mm, in order to avoid the occurrence of mechanical discontinuities in the mortar.En este trabajo se han estudiado las propiedades químico-mineralógicas, texturales y físico-mecánicas de morteros de cal hidráulica elaborados con áridos silíceo y calcítico. Estos morteros se han curado al 60% y 90% de humedad relativa, con el fin de evaluar las eventuales diferencias en las propiedades petrofísicas de los morteros una vez endurecidos y así establecer cuál de los dos ambientes es recomendable durante la aplicación y fraguado de morteros de cal hidráulica destinados a obras de restauración. Se ha encontrado que el uso de un árido de composición calcítica y el curado al 90% de humedad relativa dan lugar a morteros hidráulicos con mejores características texturales y propiedades mecánicas. De todas formas, estas características dependen principalmente del tamaño máximo del árido empleado, que debería ser inferior a 6 mm para evitar discontinuidades mecánicas en el mortero.This study was financially supported by the Spanish research group RNM179 of the Junta de Andalucía, by the research project MAT-2012-34473 and by the Institute of Conservation and Restoration of Cultural Heritage of the CICOP foundation (ICON-CICOP)
Accurate placement of epiescleral plaque in brachytherapy of choroideal melanoma
Salvadó Jassans, JosepPla general de l'obra: A Lluís Millet. Es veu la figura, en bronze,
del músic i fundador de l'Orfeó Català, en el gest de dirigir.
Està situada a l'exterior del Palau de la Música Catalana
Colonization of Vitis vinifera L. by the Endophyte Trichoderma sp. Strain T154: Biocontrol Activity Against Phaeoacremonium minimum
[EN] Trichoderma strains used in biological control products usually exhibit high efficiency in the control of plant diseases. However, their behavior under field conditions is difficult to predict. In addition, the potential of indigenous strains has been poorly assayed as well as their possible behavior as endophytes. Hence, niche colonization is a key feature for an effective protection. In this study, we aimed to: (i) explore the possibility of using a new Trichoderma strain isolated from vine to control pathogens, (ii) study the in planta interaction with the pathogen Phaeoacremonium minimum W. Gams, Crous, M.J. Wingf. & L. Mugnai (formerly Phaeoacremonium aleophilum), a pioneer fungus involved in Grapevine Trunk Diseases (GTDs) such as esca. For this purpose, fluorescently tagged Trichoderma sp. T154 and a P. minimum strain were used for scanning electron microscopy and confocal scanning laser microscopy analyses. Data showed that the Trichoderma strain is able to colonize plants up to 12 weeks post inoculation and is located in xylem, fibers, as well as in parenchymatic tissues inside the wood. The beneficial fungus reduced colonization of the esca-related pathogen colonizing the same niches. The main observed mechanism involved in biocontrol of Trichoderma against the esca pathogen was spore adhesion, niche exclusion and only few typical hypha coiling was found between Trichoderma and the pathogen. These results suggest that the Trichoderma strain has potential for reducing the colonization of Phaeoacremonium minimum and thus, an inoculation of this biological control agent can protect the plant by limiting the development of GTD, and the strain can behave as an endophyte.SIThe grant awarded to GC-H (FPU15/04681) comes from the Ministry of Education, Culture, and Sport (Spain). We thank Pago de Carraovejas winery for the project “GLOBALVITI IDI- 20120746” “Solució n global para mejorar la producció n vitivinı́ cola frente al cambio climá tico basada en robó tica, tecnologı́ a IT y en estrategias biotecnoló gicas y de manejo del viñedo” (Global solution for enhancing viticulture production against: climatic change based on: robotics, IT technology, biotechnological strategies, and vineyard management) that was granted by the Centro para el Desarrollo Tecnoló gico Industrial –CDTI-. SC and MG received funding via DaFNE Project Nr. 101384 from the Austrian Federal Ministry for Sustainability and Tourism (BMNT)
Constructor paralelo de planificaciones
Scheduling es un área activa de investigación en Inteligencia Artificial Aplicada. El interés en esta área es planificar adecuadamente la asignación de un número limitado de recursos a determinadas tareas que se deben desarrollar en el tiempo. Existen un número de técnicas heurísticas que han realizado contribuciones notables al problema de scheduling, entre ellas los algoritmos genéticos y otras variantes de la Computación Evolutiva. Estos algoritmos tienen la capacidad de descubrir planificaciones cercanas a las óptimas mucho más rápido debido a su paralelismo implícito. Varias implementaciones ya realizadas en esta dirección muestran que los algoritmos genéticos trabajan mejor cuando en la representación del cromosoma que utilizan se incorpora conocimiento específico del problema de modo tal que permita trabajar con operadores de recombinación avanzados. La elección de este tipo de representación indirecta del cromosoma requiere de un decodificador o "schedulers builder ", el cual transforme la representación del cromosoma en una planificación legal. En otras palabras los schedule builder deben garantizar la factibilidad y consistencia de cada planificación.Eje: Procesamiento concurrente, paralelo y distribuido. Procesamiento de imágenes.Red de Universidades con Carreras en Informática (RedUNCI
Vineyard Management and Physicochemical Parameters of Soil Affect Native Trichoderma Populations, Sources of Biocontrol Agents against Phaeoacremonium minimum
[EN] Native strains of Trichoderma in vineyard soil represent an opportunity for reducing the
incidence of grapevine trunk diseases (GTDs) in vineyards. Moreover, its relationship with the
environment (physicochemical soil characteristics and farming management practices) remains
unclear. In the current study, a survey was carried out on farming management used by viticulturists,
and soil samples were studied to analyze their physicochemical properties and to isolate
Trichoderma strains. Later, statistical analyses were performed to identify possible correlations between
Trichoderma populations, soil management and soil characteristics. In addition, in vitro tests,
including antibiosis and mycoparasitism, were performed to select those Trichoderma strains able to
antagonize Phaeoacremonium minimum. In this study a positive correlation was found between the
iron content and pH in the soil, and a lower pH increases Trichoderma populations in soils. Vineyard
management also affects Trichoderma populations in the soil, negatively in the case of fertilization
and tillage and positively in the case of herbicide spraying. Two Trichoderma native strains were
selected as potential biocontrol agents (Trichoderma gamsii T065 and Trichoderma harzianum T087)
using antibiosis and mycoparasitism as mechanisms of action. These results led to the conclusion
that native Trichoderma strains hold great potential as biological control agents and as producers of
secondary metabolites.SIThis research was funded by project GLOBALVITI ‘Solución global para mejorar la’ Centro para el Desarrollo Tecnológico Industrial–CDTI—(Madrid, Spain) Project, GLOBALVITI project (CIEN Program) IDI-20160746, the project LowpHwine (CIEN Program) IDI ‘Estudio de nuevos factores relacionados con el suelo, la planta y la microbiota enológica que influyen en el equilibrio de la acidez de los vinos y en su garantía de calidad y estabilidad en climas cálidos’ and Bodega Pago de Carraovejas S.L.U. Thanks to all the wineries and viticulturists who kindly let us sample their vineyards. Thanks also to the research staff of the GUIIAS group for their technical support
Constructor paralelo de planificaciones
Scheduling es un área activa de investigación en Inteligencia Artificial Aplicada. El interés en esta área es planificar adecuadamente la asignación de un número limitado de recursos a determinadas tareas que se deben desarrollar en el tiempo. Existen un número de técnicas heurísticas que han realizado contribuciones notables al problema de scheduling, entre ellas los algoritmos genéticos y otras variantes de la Computación Evolutiva. Estos algoritmos tienen la capacidad de descubrir planificaciones cercanas a las óptimas mucho más rápido debido a su paralelismo implícito. Varias implementaciones ya realizadas en esta dirección muestran que los algoritmos genéticos trabajan mejor cuando en la representación del cromosoma que utilizan se incorpora conocimiento específico del problema de modo tal que permita trabajar con operadores de recombinación avanzados. La elección de este tipo de representación indirecta del cromosoma requiere de un decodificador o "schedulers builder ", el cual transforme la representación del cromosoma en una planificación legal. En otras palabras los schedule builder deben garantizar la factibilidad y consistencia de cada planificación.Eje: Procesamiento concurrente, paralelo y distribuido. Procesamiento de imágenes.Red de Universidades con Carreras en Informática (RedUNCI
Activation of the Receptor Tyrosine Kinase, RET, improves long-term Hematopoietic Stem Cell outgrowth and potency
Expansion of Human Hematopoietic Stem Cells (HSCs) is a rapidly advancing field showing great promise for clinical applications. Recent evidence has implicated the nervous system and glial family ligands (GFLs) as potential drivers of hematopoietic survival and self-renewal in the bone marrow niche, but how to apply this to HSC maintenance and expansion is yet to be explored. We demonstrate a role for the GFL receptor, RET, at the cell surface of HSCs, in mediating sustained cellular growth, resistance to stress and improved cell survival throughout in vitro expansion. HSCs treated with the key RET ligand/co-receptor complex, GDNF/GFRa1, show improved progenitor function at primary transplantation and improved long-term HSC function at secondary transplantation. Finally, we demonstrate that RET drives a multi-faceted intracellular signalling pathway, including key signalling intermediates AKT, ERK1/2, NFkB and p53, responsible for a wide range of cellular and genetic responses which improve cell growth and survival under culture conditions
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