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showing 10 items of 2571 documents
A unified vegetation index for quantifying the terrestrial biosphere
2021
[EN] Empirical vegetation indices derived from spectral reflectance data are widely used in remote sensing of the biosphere, as they represent robust proxies for canopy structure, leaf pigment content, and, subsequently, plant photosynthetic potential. Here, we generalize the broad family of commonly used vegetation indices by exploiting all higher-order relations between the spectral channels involved. This results in a higher sensitivity to vegetation biophysical and physiological parameters. The presented nonlinear generalization of the celebrated normalized difference vegetation index (NDVI) consistently improves accuracy in monitoring key parameters, such as leaf area index, gross prim…
An Empirical Evaluation of the Utility of Convex Hull and Standard Ellipse Areas for Assessing Population Niche Widths from Stable Isotope Data
2013
Stable isotope analyses are increasingly employed to characterise population niche widths. The convex hull area (TA) in a δ¹³C–δ¹⁵N biplot has been used as a measure of isotopic niche width, but concerns exist over its dependence on sample size and associated difficulties in among-population comparisons. Recently a more robust method was proposed for estimating and comparing isotopic niche widths using standard ellipse areas (SEA), but this approach has yet to be tested with empirical stable isotope data. The two methods measure different kind of isotopic niche areas, but both are now widely used to characterise isotopic niche widths of populations. We used simulated data and an extensive e…
Interannual memory effects for spring NDVI in semi-arid South Africa
2008
[1] Almost 20 years of Normalized Difference Vegetative Index (NDVI) and precipitation (PPT) data are analysed to better understand the interannual memory effects on vegetation dynamics observed at regional scales in Southern Africa (SA). The study focuses on a semi-arid region (25°S–31°S; 21°E–26°E) during the austral early summer (September–December). The memory effects are examined using simple statistical approaches (linear correlations and regressions) which require the definition of an early summer vegetation predictand (December NDVI minus September NDVI) and a consistent set of potential predictors (rainfall amount, number of rainy days, rainfall intensity, NDVI and Rain-Use-Efficie…
Regulation of endocytosis by external stimuli in plant cells
2009
International audience; Endocytosis is an essential process for the normal growth and development of eukaryotic cells. This mini-review presents an overview of endocytosis regulation in challenging environmental conditions such as nutrient availability, hormonal treatment or abiotic/biotic stress in plant cells. Recent data establishing a relationship between endocytosis and reactive oxygen species (ROS) production are also discussed.
The influence of temperature model assumptions on the prognosis accuracy of extinction risk
2000
Abstract For a species whose abundance is well-known to correlate on the degree of heat different temperature model assumptions may affect the prognosis accuracy of persistence. Likewise, year-to-year autocorrelations in weather fluctuations are known to decrease extinction risk. Thus, we investigated the grey bush cricket Platycleis albopunctata . For this species is known that growth and reproduction is mainly influenced by temperature. We developed a stochastic individual based model for the bush cricket. This day–degree model described the demographic growth of the species that depends on temperature. Daily temperatures were generated by five different methods: (i) temperatures were seq…
Dynamic Modeling of Planar Multi-Link Flexible Manipulators
2021
A closed-form dynamic model of the planar multi-link flexible manipulator is presented. The assumed modes method is used with the Lagrangian formulation to obtain the dynamic equations of motion. Explicit equations of motion are derived for a three-link case assuming two modes of vibration for each link. The eigenvalue problem associated with the mass boundary conditions, which changes with the robot configuration and payload, is discussed. The time-domain simulation results and frequency-domain analysis of the dynamic model are presented to show the validity of the theoretical derivation.
Anomalías congénitas cardíacas en la Comunitat Valenciana 2007-2014, el registro poblacional de anomalías congénitas
2020
Resumen: Introducción: Las anomalías congénitas cardíacas (ACC) son el tipo de anomalías congénitas (AC) mayores de más prevalencia y gravedad. El objetivo fue determinar la frecuencia y distribución de las ACC en la Comunitat Valenciana desde 2007 hasta 2014, describiendo las características comunes de los pacientes y sus madres. Material y Métodos: Se seleccionaron del Registro poblacional de AC de la Comunitat Valenciana los pacientes con ACC nacidos vivos, nacidos muertos e interrupciones voluntarias del embarazo entre 2007-2014 (códigos Q20-Q26 de la Clasificación Internacional de Enfermedades 10.ª Revisión, Asociación Pediátrica Británica). Se calculó la prevalencia por 10.000 nacidos…
Consumo de medicamentos en el embarazo y riesgo de anomalías congénitas en la Comunitat Valenciana
2017
Resumen: Antecedentes: El consumo de medicamentos durante el embarazo se ha incrementado en las últimas décadas. Objetivo: Identificar el riesgo de anomalías congénitas (AC) asociado a la utilización de medicamentos en atención ambulatoria en embarazadas residentes en la Comunitat Valenciana. Métodos: Estudio de casos-controles, considerando caso a menores de un año nacidos vivos en 2009-2010 diagnosticados de AC y residentes en la Comunitat Valenciana, obtenidos del registro poblacional de AC. Los controles se seleccionaron del Registro de Metabolopatías y la medicación prescrita y dispensada se obtuvo del módulo Gestión Integral de Prestación Farmacéutica. Se calcularon las odds ratio (OR…
Synthesis and Cytotoxicity of 1,4-Dihydropyridines and an Unexpected 1,3-Oxazin-6-one
2016
Eight heterocycles have been prepared in a one-pot reaction manner based on the Hantzsch dihydropyridine synthesis. The synthesis afforded seven dihydropyridines (DHP) and one unexpected 1,3-oxazin-6-one. Their structures were confirmed based on NMR spectroscopy and mass spectrometry. The obtained products have been evaluated for their cytotoxicity against eight cancer cell lines and one normal cell line. Two halogenated DHPs (7 and 8) displayed cytotoxicity toward all the nine tested cancer cell lines with IC50 values from 4.10 to 58.90 μm, while others showed selective activities. DHPs (7 and 8) bearing a Me group at C(2) and C(6) as well as a halogenated substituent at C(4′) were more an…
Phosphorylation of CENP-A on serine 7 does not control centromere function.
2019
CENP-A is the histone H3 variant necessary to specify the location of all eukaryotic centromeres via its CENP-A targeting domain and either one of its terminal regions. In humans, several post-translational modifications occur on CENP-A, but their role in centromere function remains controversial. One of these modifications of CENP-A, phosphorylation on serine 7, has been proposed to control centromere assembly and function. Here, using gene targeting at both endogenous CENP-A alleles and gene replacement in human cells, we demonstrate that a CENP-A variant that cannot be phosphorylated at serine 7 maintains correct CENP-C recruitment, faithful chromosome segregation and long-term cell viab…