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Search Results: 1 - 10 of 23871 matches for " Francisco Eugenio "
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Featured-Based Algorithm for the Automated Registration of Multisensorial / Multitemporal Oceanographic Satellite Imagery
Francisco Eugenio,Javier Marcello
Algorithms , 2009, DOI: 10.3390/a2031087
Abstract: Spatial registration of multidate or multisensorial images is required for many applications in remote sensing. Automatic image registration, which has been extensively studied in other areas of image processing, is still a complex problem in the framework of remote sensing. In this work we explore an alternative strategy for a fully automatic and operational registration system capable of registering multitemporal and multisensorial remote sensing satellite images with high accuracy and avoiding the use of ground control points, exploiting the maximum reliable information in both images (coastlines not occluded by clouds), which have been coarsely geometrically corrected only using an orbital prediction model. The automatic feature-based approach is summarized as follows: i) Reference image coastline extraction; ii) Sensed image gradient energy map estimation and iii) Contour matching, mapping function estimation and transformation of the sensed images. Several experimental results for single sensor imagery (AVHRR/3) and multisensorial imagery (AVHRR/3-SeaWiFS-MODIS-ATSR) from different viewpoints and dates have verified the robustness and accuracy of the proposed automatic registration algorithm, demonstrating its capability of registering satellite images of coastal areas within one pixel.
Fernández de Buján, Federico (con la colaboración de Luis Eugenio Oliver), Sistema contractual romano (2a ed., Madrid, Dykinson, 2004, incluye CD-Rom), 525 págs
Francisco Eugenio Díaz
Revista de estudios histórico-jurídicos , 2005,
Abstract:
Influence of the COD to sulphate ratio on the anaerobic organic matter degradation kinetics
Francisco José Vela, Marcelo Zaiat, Eugenio Foresti
Water SA , 2002,
Abstract: The influence of the COD to sulphate ratio on the substrate consumption kinetic parameters was evaluated using a differential reactor filled with polyurethane foam matrices, taken from a horizontal-flow anaerobic immobilised biomass (HAIB) reactor. Experiments were carried out with synthetic substrate containing glucose, ammonium acetate and methanol, besides sodium bicarbonate. Micronutrients were provided by adding salts and trace metals from a stock solution. The influent chemical oxygen demand (COD) was maintained as constant as possible around 2 000 mg·l-1 in all the experiments. The reactors were subjected to increasing sulphate concentrations from 100 to 2 800 mg·l-1. First-order apparent kinetic parameters (K1 a pp ) decreased from 1.96 x 10-4 to 1.55 x 10-4l·mg VSS-1·h-1 as the COD to sulphate ratio decreased from 22.6 to 0.8. The progressive but moderate inhibition of the organic matter conversion observed indicates that high sulphate concentrations can be accommodated in HAIB reactors even at very low COD to sulphate ratios. WaterSA Vol.28(2) 2002: 213-216
Holographic Gravitational Anomaly in First and Second Order Hydrodynamics
Megias, Eugenio;Pena-Benitez, Francisco
High Energy Physics - Phenomenology , 2013,
Abstract: We compute, in the framework of the fluid/gravity correspondence, the transport coefficients of a relativistic fluid affected by chiral and gauge-gravitational anomalies, including external electromagnetic fields. The computation is performed at first and second order in the hydrodynamical expansion. We use a 5-dim holographic model with pure gauge and mixed gauge-gravitational Chern-Simons terms in the action. We reproduce at first order previous results on the anomaly induced current of a magnetic field and a vortex in a relativistic fluid, and compute at second order the anomalous and non anomalous transport coefficients by using a Weyl covariant formalism. We find a dissipative and anomalous correction to the chiral magnetic conductivity due to the time dependence of the magnetic field. We also find a new contribution from the mixed gauge-gravitational anomaly to the shear waves dispersion relation. The role played by the chiral and gravitational anomalies in other transport coefficients is discussed.
Holographic Gravitational Anomaly in First and Second Order Hydrodynamics
Eugenio Megias,Francisco Pena-Benitez
Physics , 2013, DOI: 10.1007/JHEP05(2013)115
Abstract: We compute, in the framework of the fluid/gravity correspondence, the transport coefficients of a relativistic fluid affected by chiral and gauge-gravitational anomalies, including external electromagnetic fields. The computation is performed at first and second order in the hydrodynamical expansion. We use a 5-dim holographic model with pure gauge and mixed gauge-gravitational Chern-Simons terms in the action. We reproduce at first order previous results on the anomaly induced current of a magnetic field and a vortex in a relativistic fluid, and compute at second order the anomalous and non anomalous transport coefficients by using a Weyl covariant formalism. We find a dissipative and anomalous correction to the chiral magnetic conductivity due to the time dependence of the magnetic field. We also find a new contribution from the mixed gauge-gravitational anomaly to the shear waves dispersion relation. The role played by the chiral and gravitational anomalies in other transport coefficients is discussed.
Fluid/Gravity Correspondence, Second Order Transport and Gravitational Anomaly
Eugenio Megias,Francisco Pena-Benitez
Physics , 2013, DOI: 10.1051/epjconf/20146604018
Abstract: We study the transport properties of a relativistic fluid affected by chiral and gauge-gravitational anomalies. The computation is performed in the framework of the fluid/gravity correspondence for a 5 dim holographic model with Chern-Simons terms in the action. We find new anomalous and non anomalous transport coefficients, as well as new contributions to the existing ones coming from the mixed gauge-gravitational anomaly. Consequences for the shear waves dispersion relation are analyzed.
Consequences of phosphoenolpyruvate:sugar phosphotranferase system and pyruvate kinase isozymes inactivation in central carbon metabolism flux distribution in Escherichia coli
Meza Eugenio,Becker Judith,Bolivar Francisco,Gosset Guillermo
Microbial Cell Factories , 2012, DOI: 10.1186/1475-2859-11-127
Abstract: Background In Escherichia coli phosphoenolpyruvate (PEP) is a key central metabolism intermediate that participates in glucose transport, as precursor in several biosynthetic pathways and it is involved in allosteric regulation of glycolytic enzymes. In this work we generated W3110 derivative strains that lack the main PEP consumers PEP:sugar phosphotransferase system (PTS-) and pyruvate kinase isozymes PykA and PykF (PTS-pykA- and PTS-pykF-). To characterize the effects of these modifications on cell physiology, carbon flux distribution and aromatics production capacity were determined. Results When compared to reference strain W3110, strain VH33 (PTS-) displayed lower specific rates for growth, glucose consumption and acetate production as well as a higher biomass yield from glucose. These phenotypic effects were even more pronounced by the additional inactivation of PykA or PykF. Carbon flux analysis revealed that PTS inactivation causes a redirection of metabolic flux towards biomass formation. A cycle involving PEP carboxylase (Ppc) and PEP carboxykinase (Pck) was detected in all strains. In strains W3110, VH33 (PTS-) and VH35 (PTS-, pykF-), the net flux in this cycle was inversely correlated with the specific rate of glucose consumption and inactivation of Pck in these strains caused a reduction in growth rate. In the PTS- background, inactivation of PykA caused a reduction in Ppc and Pck cycling as well as a reduction in flux to TCA, whereas inactivation of PykF caused an increase in anaplerotic flux from PEP to OAA and an increased flux to TCA. The wild-type and mutant strains were modified to overproduce L-phenylalanine. In resting cells experiments, compared to reference strain, a 10, 4 and 7-fold higher aromatics yields from glucose were observed as consequence of PTS, PTS PykA and PTS PykF inactivation. Conclusions Metabolic flux analysis performed on strains lacking the main activities generating pyruvate from PEP revealed the high degree of flexibility to perturbations of the central metabolic network in E. coli. The observed responses to reduced glucose uptake and PEP to pyruvate rate of conversion caused by PTS, PykA and PykF inactivation included flux rerouting in several central metabolism nodes towards anabolic biosynthetic reactions, thus compensating for carbon limitation in these mutant strains. The detected cycle involving Ppc and Pck was found to be required for maintaining the specific growth and glucose consumption rates in all studied strains. Strains VH33 (PTS-), VH34 (PTS-pykA-) and VH35 (PTS-pykF-) have useful prop
ANALYSES OF MITOCHONDRIAL DNA POLYMORPHISMS IN SKELETAL REMAINS AND EXTANT POPULATIONS OF NORTHERN CHILE
Mauricio Moraga,Eugenio Aspillaga,Pilar Carvallo,Francisco Rothhammer
Chungará (Arica) - Revista de Antropología Chilena , 2000,
Abstract:
Frequency dependence of the Chiral Vortical Effect
Karl Landsteiner,Eugenio Megias,Francisco Pe?a Benítez
Physics , 2013, DOI: 10.1103/PhysRevD.90.065026
Abstract: We study the frequency dependence of all the chiral vortical and magnetic conductivities for a relativistic gas of free chiral fermions and for a strongly coupled conformal field theory with holographic dual in four dimensions. Both systems have gauge and gravitational anomalies, and we compute their contribution to the conductivities. The chiral vortical conductivities and the chiral magnetic conductivity in the energy current show a frequency dependence in the form of a delta centered at zero frequency. This highly discontinuous behavior is a natural consequence of the Ward identities that include the energy momentum tensor. We discuss the physical interpretation of this result and its possible implications for the quark gluon plasma as created in heavy ion collisions. In the Appendix we discuss why the chiral magnetic effect seems to vanish in the consistent current for a particular implementation of the axial chemical potential.
Gravitational Anomaly and Transport
Karl Landsteiner,Eugenio Megias,Francisco Pena-Benitez
Physics , 2011, DOI: 10.1103/PhysRevLett.107.021601
Abstract: Quantum anomalies give rise to new transport phenomena. In particular a magnetic field can induce an anomalous current via the chiral magnetic effect and a vortex in the relativistic fluid can also induce a current via the chiral vortical effect. The related transport coefficients can be calculated via Kubo formulas. We evaluate the Kubo formula for the anomalous vortical conductivity at weak coupling and show that it receives contributions proportional to the gravitational anomaly coefficient. The gravitational anomaly gives rise to an anomalous vortical effect even for an uncharged fluid.
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