143 research outputs found
Modeling Biomass Production in Seasonal Wetlands Using MODIS NDVI Land Surface Phenology
Plant primary production is a key driver of several ecosystem functions in seasonal marshes, such as water purification and secondary production by wildlife and domestic animals. Knowledge of the spatio-temporal dynamics of biomass production is therefore essential for the management of resources—particularly in seasonal wetlands with variable flooding regimes. We propose a method to estimate standing aboveground plant biomass using NDVI Land Surface Phenology (LSP) derived from MODIS, which we calibrate and validate in the Doñana National Park’s marsh vegetation. Out of the different estimators tested, the Land Surface Phenology maximum NDVI (LSP-Maximum-NDVI) correlated best with ground-truth data of biomass production at five locations from 2001–2015 used to calibrate the models (R2 = 0.65). Estimators based on a single MODIS NDVI image performed worse (R2 ≤ 0.41). The LSP-Maximum-NDVI estimator was robust to environmental variation in precipitation and hydroperiod, and to spatial variation in the productivity and composition of the plant community. The determination of plant biomass using remote-sensing techniques, adequately supported by ground-truth data, may represent a key tool for the long-term monitoring and management of seasonal marsh ecosystems.We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI).David Aragonés, Isabel Afán, Ricardo Díaz-Delgado and Diego García Díaz (EBD-LAST)
provided support for remote-sensing and LSP analyses. Alfredo Chico, José Luis del Valle and Rocío Fernández
Zamudio (ESPN, ICTS-RBD) provided logistic support and taxonomic expertise during the field work (validation
dataset). Ernesto García and Cristina Pérez assisted with biomass harvesting and processing (calibration dataset).
Gerrit Heil provided support in the project design. This study received funding from Ministerio de Medio
Ambiente-Parque Nacional de Doñana, Consejeria de Medio Ambiente, Junta de Andalucia (1999–2000): RNM118
Junta de Andalucia (2003); the European Union’s Horizon 2020 Research and Innovation Program under grant
agreement No. 641762 to ECOPOTENTIAL project; and the Spanish Ministry of Economy, Plan Estatal de I+D+i
2013–2016, under grant agreement CGL2016-81086-R to GRAZE project
Magnetic-dipole spin effects in noncommutative quantum mechanics
A general three-dimensional noncommutative quantum mechanical system mixing spatial and spin degrees of freedom is proposed. The analogous of the harmonic oscillator in this description contains a magnetic dipole interaction and the ground state is explicitly computed and we show that it is infinitely degenerated and implying a spontaneous symmetry breaking. The model can be straightforwardly extended to many particles and the main above properties are retained. Possible applications to the Bose-Einstein condensation with dipole-dipole interactions are briefly discussed.Instituto de Física La Plat
Competencias adquiridas y aplicadas por pasantes del Instituto de Fisiopatología Cardiovascular
En Argentina, los alumnos universitarios participan poco en investigación. El Instituto de Fisiopatología Cardiovascular (INFICA), Facultad de Medicina, Universidad de Buenos Aires, los incluyó en tareas investigativas desde 1992. El objetivo del trabajo es analizar qué competencias adquirieron quienes fueron o son pasantes del INFICA y en qué aspectos de su vida académica y profesional las aplican. Se administró una encuesta estructurada, voluntaria y anónima, con datos personales y académicos, conocimientos y habilidades adquiridas y utilidad de los mismos. La tasa de respuesta fue: 66%; 71% fueron mujeres; edad promedio 28,7 años (DE= 7,37). El 88% tiene como carrera medicina, siendo el 52%, graduado. Los alumnos aprendieron recopilación (86,6%) y análisis (80%) de datos. El 80% lo utiliza para comprender temas en clases y el 60% para elaborar trabajos escritos. El 94% de los graduados realizó formación de postgrado, aplicando las siguientes competencias: análisis (93,3%) y recopilación (80%) de datos y elaboración y exposición de trabajos científicos (80%). Las utilizan en la participación (93,3%) y comprensión (73.3%) de temas en actividades académicas. El 66% de los graduados tiene actividad profesional, aplicando las competencias en exposición (100%) y elaboración (90,9%) de trabajos científicos. En consecuencia, los pasantes adquieren competencias relacionadas con recopilar, analizar datos y elaborar y exponer trabajos científicos, siendo aplicables en varios aspectos de su formación y profesión. En definitiva, la pasantía les ha brindado las bases a los futuros profesionales acerca de la metodología de la investigación e incentivado la producción científica.Fil: Rancich, Ana María. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Bioquímica y Medicina Molecular. Universidad de Buenos Aires. Facultad Medicina. Instituto de Bioquímica y Medicina Molecular; ArgentinaFil: Méndez Diodati, Nahuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Bioquímica y Medicina Molecular. Universidad de Buenos Aires. Facultad Medicina. Instituto de Bioquímica y Medicina Molecular; ArgentinaFil: Merino, Sabrina F.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Bioquímica y Medicina Molecular. Universidad de Buenos Aires. Facultad Medicina. Instituto de Bioquímica y Medicina Molecular; ArgentinaFil: Donato, Pablo Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Bioquímica y Medicina Molecular. Universidad de Buenos Aires. Facultad Medicina. Instituto de Bioquímica y Medicina Molecular; ArgentinaFil: Gelpi, Ricardo Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Bioquímica y Medicina Molecular. Universidad de Buenos Aires. Facultad Medicina. Instituto de Bioquímica y Medicina Molecular; Argentin
On the algebraic structure of rotationally invariant two-dimensional Hamiltonians on the noncommutative phase space
We study two-dimensional Hamiltonians in phase space with noncommutativity both in coordinates and momenta. We consider the generator of rotations on the noncommutative plane and the Lie algebra generated by Hermitian rotationally invariant quadratic forms of noncommutative dynamical variables. We show that two quantum phases are possible, characterized by the Lie algebras sl (2, ℝ) or su(2) according to the relation between the noncommutativity parameters, with the rotation generator related with the Casimir operator. From this algebraic perspective, we analyze the spectrum of some simple models with nonrelativistic rotationally invariant Hamiltonians in this noncommutative phase space, such as the isotropic harmonic oscillator, the Landau problem and the cylindrical well potential.Instituto de Física La Plat
On the algebraic structure of rotationally invariant two-dimensional Hamiltonians on the noncommutative phase space
We study two-dimensional Hamiltonians in phase space with noncommutativity both in coordinates and momenta. We consider the generator of rotations on the noncommutative plane and the Lie algebra generated by Hermitian rotationally invariant quadratic forms of noncommutative dynamical variables. We show that two quantum phases are possible, characterized by the Lie algebras sl (2, ℝ) or su(2) according to the relation between the noncommutativity parameters, with the rotation generator related with the Casimir operator. From this algebraic perspective, we analyze the spectrum of some simple models with nonrelativistic rotationally invariant Hamiltonians in this noncommutative phase space, such as the isotropic harmonic oscillator, the Landau problem and the cylindrical well potential.Instituto de Física La Plat
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Methodology for the analysis and comparison of protocols for glycaemic control in intensive care.
RATIONALE, AIMS, AND OBJECTIVES: The practice of glycaemic control of critically ill patients admitted to intensive care units (ICUs) is guided by clinical management protocols, designed locally by the ICUs. These protocols differ significantly in their aims and methods. The aim of this study was to develop a standardized methodology for the systematic and objective analysis and comparison of protocols for glycaemic control implemented in any ICU. METHOD: The protocols for glycaemic control implemented in seven ICUs of a UK-based ICU network were analysed using techniques of inductive content analysis, through an open coding process and the framework method. This involved the identification and classification of protocol instructions for glycaemic control, as well as of the processes and decisions pertaining to each of these instructions. These were used to develop a framework for the structured and systematic description and comparison of the protocols' contents, and to develop a technique for the protocols' graphic visualization. RESULTS: The following elements were identified or developed: (1) 35 quantifiable variables and 11 non-quantifiable subjects that could be present in an ICU protocol for glycaemic control, to be used as a framework for the description and comparison of contents; (2) a technique for condensing a protocol into a single, comprehensive flowchart; (3) using these flowcharts, a method for assessing the complexity and comprehensiveness of the protocols. CONCLUSIONS: The methodology developed in this study will allow for any future work analysing the contents of glycaemic control protocols to be carried out in a structured and standardized way. This may be done either as a standalone study, or as the essential first step in any investigation on the impact of new protocols. In turn, the methodology will facilitate the performance of regional, national, and international comparisons, demonstrating the usefulness of this study at a global scale
Arsenic and chromium topsoil levels and cancer mortality in Spain
Spatio-temporal cancer mortality studies in Spain have revealed patterns for some tumours which display a distribution that is similar across the sexes and persists over time. Such characteristics would be common to tumours that shared risk factors, including the chemical soil composition. The objective of the present study is to assess the association between levels of chromium and arsenic in soil and the cancer mortality. This is an ecological cancer mortality study at municipal level, covering 861,440 cancer deaths in 7917 Spanish mainland towns from 1999 to 2008. Chromium and arsenic topsoil levels (partial extraction) were determined by ICP-MS at 13,317 sampling points. To estimate the effect of these concentrations on mortality, we fitted Besag, York and Mollié models, which included, as explanatory variables, each town’s chromium and arsenic soil levels, estimated by kriging. In addition, we also fitted geostatistical-spatial models including sample locations and town centroids (non-aligned data), using the integrated nested Laplace approximation (INLA) and stochastic partial differential equations (SPDE). All results were adjusted for socio-demographic variables and proximity to industrial emissions. The results showed a statistical association in men and women alike, between arsenic soil levels and mortality due to cancers of the stomach, pancreas, lung and brain and non-Hodgkin’s lymphomas (NHL). Among men, an association was observed with cancers of the prostate, buccal cavity and pharynx, oesophagus, colorectal and kidney. Chromium topsoil levels were associated with mortality among women alone, in cancers of the upper gastrointestinal tract, breast and NHL. Our results suggest that chronic exposure arising from low levels of arsenic and chromium in topsoil could be a potential risk factor for developing cancer. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11356-016-6806-y) contains supplementary material, which is available to authorized users
Retrieval of canopy water content of different crop types with two new hyperspectral indices: Water Absorption Area Index and Depth Water Index
Crop canopy water content (CWC) is an essential indicator of the crop's physiological state. While a diverse range of vegetation indices have earlier been developed for the remote estimation of CWC, most of them are defined for specific crop types and areas, making them less universally applicable. We propose two new water content indices applicable to a wide variety of crop types, allowing to derive CWC maps at a large spatial scale. These indices were developed based on PROSAIL simulations and then optimized with an experimental dataset (SPARC03; Barrax, Spain). This dataset consists of water content and other biophysical variables for five common crop types (lucerne, corn, potato, sugar beet and onion) and corresponding top-of-canopy (TOC) reflectance spectra acquired by the hyperspectral HyMap airborne sensor. First, commonly used water content index formulations were analysed and validated for the variety of crops, overall resulting in a R2 lower than 0.6. In an attempt to move towards more generically applicable indices, the two new CWC indices exploit the principal water absorption features in the near-infrared by using multiple bands sensitive to water content. We propose the Water Absorption Area Index (WAAI) as the difference between the area under the null water content of TOC reflectance (reference line) simulated with PROSAIL and the area under measured TOC reflectance between 911 and 1271 nm. We also propose the Depth Water Index (DWI), a simplified four-band index based on the spectral depths produced by the water absorption at 970 and 1200 nm and two reference bands. Both the WAAI and DWI outperform established indices in predicting CWC when applied to heterogeneous croplands, with a R2 of 0.8 and 0.7, respectively, using an exponential fit. However, these indices did not perform well for species with a low fractional vegetation cover (<30%). HyMap CWC maps calculated with both indices are shown for the Barrax region. The results confirmed the potential of using generically applicable indices for calculating CWC over a great variety of crops
Magnetic-dipole spin effects in noncommutative quantum mechanics
A general three-dimensional noncommutative quantum mechanical system mixing spatial and spin degrees of freedom is proposed. The analogous of the harmonic oscillator in this description contains a magnetic dipole interaction and the ground state is explicitly computed and we show that it is infinitely degenerated and implying a spontaneous symmetry breaking. The model can be straightforwardly extended to many particles and the main above properties are retained. Possible applications to the Bose-Einstein condensation with dipole-dipole interactions are briefly discussed.Instituto de Física La Plat
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