7 research outputs found
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Relation between leaf area index and NDVI for subarctic deciduous vegetation
We consider the relationship between leaf area index (LAI) and normalised difference vegetation index (NDVI) for green-leaf vegetation from a subarctic study site, specifically to test whether relationships optimised for lower-latitude vegetation can be assumed to hold at higher latitudes. We focus attention particularly on dwarf-shrub vegetation, which has received little previous investigation.
We have collected hyperspectral measurements of the optical properties (reflectance and absorptance) of single leaves from dwarf shrub and tree species common to northern European Russia, and have developed a simple physical model of the properties of assemblages (‘leaf stacks’) of these leaves. The model is shown to provide a satisfactory explanation of the effect of varying the number of leaves in a stack on its NDVI, and can be easily adapted to make simple measurements using relatively inexpensive equipment. Our results show that the LAI-NDVI relationship for a vegetation canopy will saturate (approach within 10% of its limiting value) when the LAI reaches a value of around 2 to 3. Values this low are not uncommon in subarctic vegetation. It is also shown that dwarf shrub vegetation may show lower NDVI than trees for the same LAI.British Council Institutional Links Programme, grant 352397111
Ministry of Science and Higher Education of the Russian Federation, project RFMEF161618X009
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Three decades of remote sensing subarctic vegetation in northern Russia: A case study in science diplomacy
Abstract
The vegetation at and beyond the northern edge of the world’s boreal forest plays an important though imperfectly understood role in the climate system. This is particularly true within Russia, where only a small proportion of the boreal land area has been studied in depth, and little is known about its recent evolution over time. We describe a long-term collaboration between institutions in Russia and the United Kingdom, aimed at developing a better understanding of high-latitude vegetation in Russia using remote sensing methods. The focus of the collaboration has varied over time; in its most recent form, it is concerned with the dynamics of the Russian boreal forest during the 21st century and its relation to climate change. We discuss the support framework within which it has been developed and reflect on its relationship to science diplomacy. We consider the factors that have contributed to the success of a decades-long international collaboration and make recommendations as to how such joint efforts can be encouraged in future.British Council Institutional Links grant 352397111; Ministry of Education and Science of the Russian Federation grant 14.616.21.0099; Russian Government Assingnment AAA-A19-119022190168-8; Global Britain and International Funds of the UK FCD
Post-Soviet Psychology and Individual Differences in Cognition: A Psychophysiological Perspective
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Advances in molecular quantum chemistry contained in the Q-Chem 4 program package
A summary of the technical advances that are incorporated in the fourth major release of the Q-Chem quantum chemistry program is provided, covering approximately the last seven years. These include developments in density functional theory methods and algorithms, nuclear magnetic resonance (NMR) property evaluation, coupled cluster and perturbation theories, methods for electronically excited and open-shell species, tools for treating extended environments, algorithms for walking on potential surfaces, analysis tools, energy and electron transfer modelling, parallel computing capabilities, and graphical user interfaces. In addition, a selection of example case studies that illustrate these capabilities is given. These include extensive benchmarks of the comparative accuracy of modern density functionals for bonded and non-bonded interactions, tests of attenuated second order Møller-Plesset (MP2) methods for intermolecular interactions, a variety of parallel performance benchmarks, and tests of the accuracy of implicit solvation models. Some specific chemical examples include calculations on the strongly correlated Cr2 dimer, exploring zeolite-catalysed ethane dehydrogenation, energy decomposition analysis of a charged ter-molecular complex arising from glycerol photoionisation, and natural transition orbitals for a Frenkel exciton state in a nine-unit model of a self-assembling nanotube
Advances in molecular quantum chemistry contained in the Q-Chem 4 program package
© 2014 © 2014 Taylor & Francis.A summary of the technical advances that are incorporated in the fourth major release of the Q-Chem quantum chemistry program is provided, covering approximately the last seven years. These include developments in density functional theory methods and algorithms, nuclear magnetic resonance (NMR) property evaluation, coupled cluster and perturbation theories, methods for electronically excited and open-shell species, tools for treating extended environments, algorithms for walking on potential surfaces, analysis tools, energy and electron transfer modelling, parallel computing capabilities, and graphical user interfaces. In addition, a selection of example case studies that illustrate these capabilities is given. These include extensive benchmarks of the comparative accuracy of modern density functionals for bonded and non-bonded interactions, tests of attenuated second order Møller-Plesset (MP2) methods for intermolecular interactions, a variety of parallel performance benchmarks, and tests of the accuracy of implicit solvation models. Some specific chemical examples include calculations on the strongly correlated Cr2 dimer, exploring zeolite-catalysed ethane dehydrogenation, energy decomposition analysis of a charged ter-molecular complex arising from glycerol photoionisation, and natural transition orbitals for a Frenkel exciton state in a nine-unit model of a self-assembling nanotube.Link_to_subscribed_fulltex
Advances in molecular quantum chemistry contained in the Q-Chem 4 program package
A summary of the technical advances that are incorporated in the fourth major release of the Q-Chem quantum chemistry program is provided, covering approximately the last seven years. These include developments in density functional theory methods and algorithms, nuclear magnetic resonance (NMR) property evaluation, coupled cluster and perturbation theories, methods for electronically excited and open-shell species, tools for treating extended environments, algorithms for walking on potential surfaces, analysis tools, energy and electron transfer modelling, parallel computing capabilities, and graphical user interfaces. In addition, a selection of example case studies that illustrate these capabilities is given. These include extensive benchmarks of the comparative accuracy of modern density functionals for bonded and non-bonded interactions, tests of attenuated second order Moller-Plesset (MP2) methods for intermolecular interactions, a variety of parallel performance benchmarks, and tests of the accuracy of implicit solvation models. Some specific chemical examples include calculations on the strongly correlated Cr-2 dimer, exploring zeolite-catalysed ethane dehydrogenation, energy decomposition analysis of a charged ter-molecular complex arising from glycerol photoionisation, and natural transition orbitals for a Frenkel exciton state in a nine-unit model of a self-assembling nanotube.11827616Nsciescopu