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Search Results: 1 - 10 of 324890 matches for " S. Griffa* "
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Morphological evaluation of buffelgrass cultivar “Lucero INTA-PEMAN” in drought conditions
GRIFFA, S.,RIBOTTA, A,LUNA, C,BOLLATI, G
RIA : Revista de Investigaciones Agropecuarias , 2011,
Abstract: In searching for new cultivars that are better adapted to edapho-climatic constraints existing in northwestern Argentina, mainly drought and salinity stress, a hybrid of buffelgrass (Cenchrus ciliaris L.) named Lucero INTA PEMAN was obtained by controlled crosses at the Instituto de Fitopatología y Fisiología Vegetal, INTA. The objective was to morphologically evaluate and compare Cenchrus ciliaris cv Lucero with Texas-4464, Biloela and Molopo cultivars in Dean Funes (North of the Province of Córdoba, Argentina) under drought field conditions using a randomized complete block design with three replications in two crop cycles (2006/2007 and 2007/2008) considering one-year plant and re-growth as ontogenic stages of the plant, respectively. Thirteen morphological characters were analyzed by ANOVA and DGC testing (p <0.05). Although most of the thirteen morphological characters evaluated showed decreased re-growth over one-year plants, Lucero was least affected by low water availability, showed highest values for seed production components in both ontogenic stages and was superior to Texas-4464 in biomass production characters and to Biloela and Molopo cultivars in most of them. Lucero showed a promising and considerable forage value for drought-affected regions, such as northwestern Argentina.
Evaluación morfológica del cultivar de buffelgrass “Lucero INTA-PEMAN” en condiciones de sequía
GRIFFA, S,RIBOTTA, A,LUNA, C,BOLLATI, G
RIA : Revista de Investigaciones Agropecuarias , 2011,
Abstract: En la búsqueda de nuevos cultivares nacionales mejor adaptados a las restricciones edafo-climáticas presentes en el noroeste argentino, principalmente estrés por sequía y salinidad, un híbrido de buffelgrass (Cenchrus ciliaris L.) denominado Lucero INTA-PEMAN fue obtenido mediante cruzamientos controlados en el Instituto de Fitopatología y Fisiología Vegetal (IFFIVE), INTA. El objetivo fue evaluar morfológicamente al cultivar Lucero en comparación a los cultivares Texas-4464, Biloela y Molopo, en Deán Funes (Norte de Córdoba, Argentina) a campo bajo condiciones de sequía, en un dise o en bloques completos aleatorizados con tres repeticiones y por dos ciclos de cultivo (2006/2007 y 2007/2008), considerándose como estados ontogénicos planta de un a o y rebrote, respectivamente. Se analizaron 13 caracteres morfológicos mediante ANAVA y test DGC (p<0,05). A pesar de que la expresión de la mayoría de los 13 caracteres morfológicos evaluados disminuyó en rebrote, con respecto al primer a o de implantación, Lucero INTA-PEMAN fue el menos afectado por la baja disponibilidad de agua y se comportó superior en ambos estados ontogénicos, en caracteres componentes de producción de semillas y fue similar inclusive superior, en caracteres de producción de biomasa a los cultivares Biloela, Molopo y Texas-4464. Lucero INTA-PEMAN se muestra como promisorio y de considerable valor forrajero para las regiones afectadas por sequía, tales como el noroeste argentino.
Implementation of position assimilation for ARGO floats in a realistic Mediterranean Sea OPA model and twin experiment testing
V. Taillandier,A. Griffa
Ocean Science (OS) & Discussions (OSD) , 2006, DOI: 10.5194/os-2-223-2006
Abstract: In this paper, a Lagrangian assimilation method is presented and implemented in a realistic OPA OGCM with the goal of providing an assessment of the assimilation of realistic Argo float position data. We focus on an application in the Mediterranean Sea, where in the framework of the MFSTEP project an array of Argo floats have been deployed with parking depth at 350 m and sampling interval of 5 days. In order to quantitatively test the method, the "twin experiment" approach is followed and synthetic trajectories are considered. The method is first tested using "perfect" data, i.e. without shear drift errors and with relatively high coverage. Results show that the assimilation is effective, correcting the velocity field at the parking depth, as well as the velocity profiles and the geostrophically adjusted mass field. We then consider the impact of realistic datasets, which are spatially sparse and characterized by shear drift errors. Such data provide a limited global correction of the model state, but they efficiently act on the location, intensity and shape of the described mesoscale structures of the intermediate circulation.
Implementation of position assimilation for ARGO floats in a realistic Mediterranean Sea OPA model and twin experiment testing
V. Taillandier,A. Griffa
Ocean Science Discussions (OSD) , 2006,
Abstract: In this paper, a Lagrangian assimilation method is presented and implemented in a realistic OPA OGCM with the goal of providing an assessment of the assimilation of realistic Argo float position data. We focus on an application in the Mediterranean Sea, where in the framework of the MFSTEP project an array of Argo floats have been deployed with parking depth at 350 m and sampling interval of 5 days. In order to quantitatively test the method, the ''twin experiment'' approach is followed and synthetic trajectories are considered. The method is first tested using ''perfect'' data, i.e. without shear drift errors and with relatively high coverage. Results show that the assimilation is effective, correcting the velocity field at the parking depth, as well as the velocity profiles and the geostrophically adjusted mass field. We then consider the impact of realistic datasets, which are spatially sparse and characterized by shear drift errors. Such data provide a limited global correction of the model state, but they efficiently act on the location, intensity and shape of the described mesoscale structures of the intermediate circulation.
Lenguaje, gramatica y derecho
Norberto Luiz Griffa
Sequência : Estudos Juridicos e Politicos , 1981,
Abstract:
Relationship between seed yield and its component characters in Cenchrus spp.
S. Griffa*, M. Quiroga, A. Ribotta, E. López Colomba, E. Carloni, E. Tommasino, C. Luna and K. Grunber
Electronic Journal of Plant Breeding , 2012,
Abstract: Cenchrus setigerus, C. sp., eleven obligate apomictic cultivars and a sexual line of Cenchrus ciliaris L. were studied to determinethe relationship between seed production and its component characters, through principal component analysis, path correlationanalysis and analysis of variance. A completely randomized field design was used. Ten vegetative and reproductivemorphological characters were measured. Seed production was influenced directly by panicle weight and indirectly by paniclelength, 1000 seed weight, length and width of flag leaf lamina and length of flag leaf sheath. Panicle weight showed highheritability and variability among genotypes. Hence, panicle weight can be considered a selection criterion to obtain increasedseed production in Cenchrus. The cultivar Lucero INTA PEMAN exhibited the highest panicle weight and, therefore, greatestseed production, which makes it suitable for selection as parental cultivar to obtain new germplasm in Cenchrus with high seedyield.
Assessment of the impact of TS assimilation from ARGO floats in the Mediterranean Sea
A. Griffa, A. Molcard, F. Raicich,V. Rupolo
Ocean Science (OS) & Discussions (OSD) , 2006, DOI: 10.5194/os-2-237-2006
Abstract: In this paper, the impact of assimilating Temperature (T) and Salinity (S) profiles from Argo floats in the Mediterranean Sea is quantitatively investigated using the Observing System Simulation Experiments (OSSE) approach. The impact of varying the number of floats and their launch positions is considered, using numerical simulations with a MOM model and a reduced-order multivariate Optimal Interpolation scheme (SOFA) for assimilation. Realistic float coverage and launch positions used during the first MFSTEP phase are considered, as well as "ideal" density coverage that can be envisioned for the future, corresponding to a double coverage with respect to MFSTEP and with floats released along the VOS tracks. The most effective float trajectories are identified, showing that frontal regions play a major role, and that it is crucial to maintain a sufficient coverage of them. In addition to this, a comparison is also performed between the results obtained from MEDARGO floats in ideal conditions and results from "ideal" profiles taken at fixed points along the VOS tracks, as for the XBT data. For consistency the coverage considered is double the actual XBT coverage during MFSTEP, resulting in a threefold increase in the number of profiles compared to the MEDARGO experiment. The maximum error reduction is of approximately 10%, suggesting that spatially coarser profiles from floats can be more efficient since they follow flow features.
Assessment of the impact of TS assimilation from ARGO floats in the Mediterranean Sea
A. Griffa,A. Molcard,F. Raicich,V. Rupolo
Ocean Science Discussions (OSD) , 2006,
Abstract: In this paper, the impact of assimilating Temperature (T) and Salinity (S) profiles from Argo floats in the Mediterranean Sea (MEDARGO) is quantitatively investigated using the Observing System Simulation Experiments (OSSE) approach. The impact of varying the number of floats and their launch positions is considered, using numerical simulations with a MOM model and a reduced-order multivariate Optimal Interpolation scheme (SOFA) for assimilation. Realistic launch positions used during the first MFSTEP phase are considered, as well as ''ideal'' positions that can be envisioned for the future, along the VOS tracks. The most effective float trajectories are identified, showing that frontal regions play a major role, and that it is crucial to maintain a sufficient coverage of them. In addition to this, also a qualitative comparison is performed between the results obtained from MEDARGO floats in ideal conditions and results from ''ideal'' profiles taken along the VOS (Volunteer Observing Ships) tracks, as for the XBT (Expandable Baththermograph) data.
Lagrangian turbulence in the Adriatic Sea as computed from drifter data: effects of inhomogeneity and nonstationarity
Alberto Maurizi,Annalisa Griffa,Pierre-Marie Poulain,Francesco Tampieri
Physics , 2003, DOI: 10.1029/2003JC002119
Abstract: The properties of mesoscale Lagrangian turbulence in the Adriatic Sea are studied from a drifter data set spanning 1990-1999, focusing on the role of inhomogeneity and nonstationarity. A preliminary study is performed on the dependence of the turbulent velocity statistics on bin averaging, and a preferential bin scale of 0.25 is chosen. Comparison with independent estimates obtained using an optimized spline technique confirms this choice. Three main regions are identified where the velocity statistics are approximately homogeneous: the two boundary currents, West (East) Adriatic Current, WAC (EAC), and the southern central gyre, CG. The CG region is found to be characterized by symmetric probability density function of velocity, approximately exponential autocorrelations and well defined integral quantities such as di usivity and time scale. The boundary regions, instead, are significantly asymmetric with skewness indicating preferential events in the direction of the mean flow. The autocorrelation in the along mean flow direction is characterized by two time scales, with a secondary exponential with slow decay time of 11-12 days particularly evident in the EAC region. Seasonal partitioning of the data shows that this secondary scale is especially prominent in the summer-fall season. Possible physical explanations for the secondary scale are discussed in terms of low frequency fluctuations of forcings and in terms of mean flow curvature inducing fluctuations in the particle trajectories. Consequences of the results for transport modelling in the Adriatic Sea are discussed.
Effect of boundary vibration on the frictional behavior of a dense sheared granular layer
B. Ferdowsi,M. Griffa,R. A. Guyer,P. A. Johnson,J. Carmeliet
Physics , 2014, DOI: 10.1007/s00707-014-1136-y
Abstract: We report results of 3D Discrete Element Method (DEM) simulations aiming at investigating the role of the boundary vibration in inducing frictional weakening in sheared granular layers. We study the role of different vibration amplitudes applied at various shear stress levels, for a granular layer in the stick-slip regime and in the steady-sliding regime. Results are reported in terms of friction drops and kinetic energy release associated with frictional weakening events. We find that larger vibration amplitude induces larger frictional weakening events. The results show evidence of a threshold below which no induced frictional weakening takes place. Friction drop size is found to be dependent on the shear stress at the time of vibration. A significant increase in the ratio between the number of slipping contacts to the number of sticking contacts in the granular layer is observed for large vibration amplitudes. These vibration-induced contact rearrangements enhance particle mobilization and induces a friction drop and kinetic energy release. This observation provides some insight into the grain-scale mechanisms of frictional weakening by boundary vibration in a dense sheared granular layer. In addition to characterizing the basic physics of vibration induced shear weakening, we are attempting to understand how a fault fails in the earth under seismic wave forcing. This is the well know phenomenon of dynamic earthquake triggering. We believe that the granular physics are key to this understanding.
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