232 research outputs found

    BTZ Black Hole as Solution of 3d Higher Spin Gauge Theory

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    BTZ black hole is interpreted as exact solution of 3d higher spin gauge theory. Solutions for free massless fields in BTZ black hole background are constructed with the help of the star-product algebra formalism underlying the formulation of 3d higher spin theory. It is shown that a part of higher spin symmetries remains unbroken for special values of the BTZ parameters.Comment: 31 pages, LaTeX; references correcte

    Thermal Giant Graviton with Non-commutative Dipole Field

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    Using the type II near-extremal 3D-branes solution we apply the T-duality and smeared twist to construct the supergravity backgrounds which dual to the 4D finite temperature non-commutative dipole field theories. We first consider the zero-temperature system in which, depending on the property of dipole vectors it may be N=2, N=1 or N=0 theory. We investigate the rotating D3-brane configurations moving on the spactimes and show that, for the cases of N=2 and N =1 the rotating D3-brane could be blowed up to the stable spherical configuration which is called as giant graviton and has a less energy than the point-like graviton. The giant graviton configuration is stable only if its angular momentum was less than a critical value of PcP_c which is an increasing function of the dipole strength. For the case of non-supersymmetric theory, however, the spherical configuration has a larger energy than the point-like graviton. We also find that the dipole field always render the dual giant graviton to be more stable than the point-like graviton. The relation of dual giant graviton energy with its angular momentum, which in the AdS/CFT correspondence being the operator anomalous dimension is obtained. We furthermore show that the temperature does not change the property of the giant graviton, while it will render the dual giant graviton to be unstable.Comment: Latex 20 pages, add comments about BPS bound below (3.8

    Factors promoting larch dominance in central Siberia: fire versus growth performance and implications for carbon dynamics at the boundary of evergreen and deciduous conifers

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    The relative roles of fire and climate in determining canopy species composition and aboveground carbon stocks were investigated. Measurements were made along a transect extending from the dark taiga zone of Central Siberia, where Picea and Abies dominate the 5 canopy, into the Larix zone of Eastern Siberia. We test the hypotheses that the change in canopy species composition is based (1) on climate-driven performance only, (2) on fire only, or (3) on fire-performance interactions. We show that the evergreen conifers Picea obovata and Abies sibirica are the natural late-successional species both in Central and Eastern Siberia, provided there has been no fire for an 10 extended period of time. There are no changes in the climate-driven performance of the observed species. Fire appears to be the main factor explaining the dominance of Larix. Of lesser influence were longitude, hydrology and active-layer thickness. Stand-replacing fires decreased from 300 to 50 yr between the Yenisei Ridge and the upper Tunguska. Repeated non-stand-replacing surface fires eliminated the regenera15 tion of Abies and Picea. With every 100 yr since the last fire, the percentage of Larix decreased by 20 %. Biomass of stems of single trees did not show signs of age-related decline. Relative diameter increment was 0.41±0.20% at breast height and stem volume increased linearly over time with a rate of about 0.36 tCha−1 yr−1 independent of age class and 20 species. Stand volumes reached about 130 tCha−1 (equivalent to about 520m3 ha−1). Individual trees of Larix were older than 600 yr. The maximum age and biomass seemed to be limited by fungal rot of heart wood. 60% of old Larix and Picea and 30% of Pinus sibirica trees were affected by stem rot. Implications for the future role of fire and of plant diseases are discussed.JRC.H.3-Forest Resources and Climat

    Technical note: A view from space on global flux towers by MODIS and Landsat: The FluxnetEO dataset

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    Funding Information: Acknowledgements. We thank the team at the ICOS Carbon Portal for their support in publishing the FluxnetEO data sets, with great thanks in particular to Ute Karstens and Zois Zogopoulos. SW acknowledges funding from an ESA Living Planet Fellowship in the project Vad3e mecum. Alexey Vasilevich Panov acknowledges funding from the Max Planck Society (Germany), Russian Foundation for Basic Re- search, Krasnoyarsk Territory and Krasnoyarsk Regional Fund of Science, project no. 20-45-242908. Frederik Schrader and Christian Brümmer acknowledge funds from the German Federal Ministry of Food and Agriculture (BMEL) received through Thünen Institute of Climate-Smart Agriculture. Simon Besnard acknowledges funding from the European Union through the BIOMAS-CAT (project code: 4000115192/18/I/NB) (https://eo4society.esa. int/projects/biomascat/, last access: 3 May 2022) and VERIFY (project code: BO-55-101-006) (https://cordis.europa.eu/project/id/ 776810, last access: 3 May 2022) projects. Funding Information: Financial support. This research has been supported by the Euro- Publisher Copyright: © 2022 Sophia Walther et al.The eddy-covariance technique measures carbon, water, and energy fluxes between the land surface and the atmosphere at hundreds of sites globally. Collections of standardised and homogenised flux estimates such as the LaThuile, Fluxnet2015, National Ecological Observatory Network (NEON), Integrated Carbon Observation System (ICOS), AsiaFlux, AmeriFlux, and Terrestrial Ecosystem Research Network (TERN)/OzFlux data sets are invaluable to study land surface processes and vegetation functioning at the ecosystem scale. Space-borne measurements give complementary information on the state of the land surface in the surroundings of the towers. They aid the interpretation of the fluxes and support the benchmarking of terrestrial biosphere models. However, insufficient quality and frequent and/or long gaps are recurrent problems in applying the remotely sensed data and may considerably affect the scientific conclusions. Here, we describe a standardised procedure to extract, quality filter, and gap-fill Earth observation data from the MODIS instruments and the Landsat satellites. The methods consistently process surface reflectance in individual spectral bands, derived vegetation indices, and land surface temperature. A geometrical correction estimates the magnitude of land surface temperature as if seen from nadir or 40g off-nadir. Finally, we offer the community living data sets of pre-processed Earth observation data, where version 1.0 features the MCD43A4/A2 and MxD11A1 MODIS products and Landsat Collection 1 Tier 1 and Tier 2 products in a radius of 2 km around 338 flux sites. The data sets we provide can widely facilitate the integration of activities in the eddy-covariance, remote sensing, and modelling fields.publishersversionpublishe

    Electrified BPS Giants: BPS configurations on Giant Gravitons with Static Electric Field

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    We consider D3-brane action in the maximally supersymmetric type IIB plane-wave background. Upon fixing the light-cone gauge, we obtain the light-cone Hamiltonian which is manifestly supersymmetric. The 1/2 BPS solutions of this theory (solutions which preserve 16 supercharges) are either of the form of spherical three branes, the giant gravitons, or zero size point like branes. We then construct specific classes of 1/4 BPS solutions of this theory in which static electric field on the brane is turned on. These solutions are deformations about either of the two 1/2 BPS solutions. In particular, we study in some detail 1/4 BPS configurations with electric dipole on the three sphere giant, i.e. BIons on the giant gravitons, which we hence call BIGGons. We also study BPS configurations corresponding to turning on a background uniform constant electric field. As a result of this background electric field the three sphere giant is deformed to squashed sphere, while the zero size point like branes turn into circular or straight fundamental strings in the plane-wave background, with their tension equal to the background electric field.Comment: 32 pages, 1 eps figure; v2: Presentation of derivation of light-cone Hamiltonian improved, Refs adde
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