ALBERT

Description: Atmospheric carbon dioxide records indicate that the land surface has acted as a strong global carbon sink over recent decades, with a substantial fraction of this sink probably located in the tropics, particularly in the Amazon. Nevertheless, it is unclear how the terrestrial carbon sink will evolve as climate and atmospheric composition continue to change. Here we analyse the historical evolution of the biomass dynamics of the Amazon rainforest over three decades using a distributed network of 321 plots. While this analysis confirms that Amazon forests have acted as a long-term net biomass sink, we find a long-term decreasing trend of carbon accumulation. Rates of net increase in above-ground biomass declined by one-third during the past decade compared to the 1990s. This is a consequence of growth rate increases levelling off recently, while biomass mortality persistently increased throughout, leading to a shortening of carbon residence times. Potential drivers for the mortality increase include greater climate variability, and feedbacks of faster growth on mortality, resulting in shortened tree longevity. The observed decline of the Amazon sink diverges markedly from the recent increase in terrestrial carbon uptake at the global scale, and is contrary to expectations based on models.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Brienen, R J W -- Phillips, O L -- Feldpausch, T R -- Gloor, E -- Baker, T R -- Lloyd, J -- Lopez-Gonzalez, G -- Monteagudo-Mendoza, A -- Malhi, Y -- Lewis, S L -- Vasquez Martinez, R -- Alexiades, M -- Alvarez Davila, E -- Alvarez-Loayza, P -- Andrade, A -- Aragao, L E O C -- Araujo-Murakami, A -- Arets, E J M M -- Arroyo, L -- Aymard C, G A -- Banki, O S -- Baraloto, C -- Barroso, J -- Bonal, D -- Boot, R G A -- Camargo, J L C -- Castilho, C V -- Chama, V -- Chao, K J -- Chave, J -- Comiskey, J A -- Cornejo Valverde, F -- da Costa, L -- de Oliveira, E A -- Di Fiore, A -- Erwin, T L -- Fauset, S -- Forsthofer, M -- Galbraith, D R -- Grahame, E S -- Groot, N -- Herault, B -- Higuchi, N -- Honorio Coronado, E N -- Keeling, H -- Killeen, T J -- Laurance, W F -- Laurance, S -- Licona, J -- Magnussen, W E -- Marimon, B S -- Marimon-Junior, B H -- Mendoza, C -- Neill, D A -- Nogueira, E M -- Nunez, P -- Pallqui Camacho, N C -- Parada, A -- Pardo-Molina, G -- Peacock, J -- Pena-Claros, M -- Pickavance, G C -- Pitman, N C A -- Poorter, L -- Prieto, A -- Quesada, C A -- Ramirez, F -- Ramirez-Angulo, H -- Restrepo, Z -- Roopsind, A -- Rudas, A -- Salomao, R P -- Schwarz, M -- Silva, N -- Silva-Espejo, J E -- Silveira, M -- Stropp, J -- Talbot, J -- ter Steege, H -- Teran-Aguilar, J -- Terborgh, J -- Thomas-Caesar, R -- Toledo, M -- Torello-Raventos, M -- Umetsu, R K -- van der Heijden, G M F -- van der Hout, P -- Guimaraes Vieira, I C -- Vieira, S A -- Vilanova, E -- Vos, V A -- Zagt, R J -- England -- Nature. 2015 Mar 19;519(7543):344-8. doi: 10.1038/nature14283.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉School of Geography, University of Leeds, Leeds LS2 9JT, UK. ; 1] School of Geography, University of Leeds, Leeds LS2 9JT, UK. [2] Geography, College of Life and Environmental Sciences, University of Exeter, Rennes Drive, Exeter EX4 4RJ, UK. ; 1] Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot, Berkshire SL5 7PY, UK. [2] School of Marine and Tropical Biology, James Cook University, Cairns, 4870 Queenland, Australia. ; Jardin Botanico de Missouri, Prolongacion Bolognesi Mz.e, Lote 6, Oxapampa, Pasco, Peru. ; Environmental Change Institute, School of Geography and the Environment, University of Oxford, Oxford OX1 3QK, UK. ; 1] School of Geography, University of Leeds, Leeds LS2 9JT, UK. [2] Department of Geography, University College London, Pearson Building, Gower Street, London WC1E 6BT, UK. ; School of Anthropology and Conservation, Marlowe Building, University of Kent, Canterbury CT1 3EH, UK. ; Servicios Ecosistemicos y Cambio Climatico, Jardin Botanico de Medellin, Calle 73 no. 51 D-14, C.P. 050010, Medellin, Colombia. ; Center for Tropical Conservation, Duke University, Box 90381, Durham, North Carolina 27708, USA. ; Biological Dynamics of Forest Fragment Project (INPA &STRI), C.P. 478, Manaus AM 69011-970, Brazil. ; 1] Geography, College of Life and Environmental Sciences, University of Exeter, Rennes Drive, Exeter EX4 4RJ, UK. [2] National Institute for Space Research (INPE), Av. Dos Astronautas, 1758, Sao Jose dos Campos, Sao Paulo 12227-010, Brazil. ; Museo de Historia Natural Noel Kempff Mercado, Universidad Autonoma Gabriel Rene Moreno, Casilla 2489, Av. Irala 565, Santa Cruz, Bolivia. ; Alterra, Wageningen University and Research Centre, PO Box 47, 6700 AA Wageningen, The Netherlands. ; UNELLEZ-Guanare, Programa de Ciencias del Agro y el Mar, Herbario Universitario (PORT), Mesa de Cavacas, Estado Portuguesa, 3350 Venezuela. ; Biodiversiteit en Ecosysteem Dynamica, University of Amsterdam, Postbus 94248, 1090 GE Amsterdam, The Netherlands. ; 1] Institut National de la Recherche Agronomique, UMR EcoFoG, Campus Agronomique, 97310 Kourou, French Guiana. [2] International Center for Tropical Botany, Department of Biological Sciences, Florida International University, Miami, Florida 33199, USA. ; Universidade Federal do Acre, Campus de Cruzeiro do Sul, Rio Branco, Brazil. ; INRA, UMR 1137 ''Ecologie et Ecophysiologie Forestiere'' 54280 Champenoux, France. ; Embrapa Roraima, Caixa Postal 133, Boa Vista, RR, CEP 69301-970, Brazil. ; Universidad Nacional San Antonio Abad del Cusco, Av. de la Cultura N degrees 733, Cusco, Peru. ; 1] School of Geography, University of Leeds, Leeds LS2 9JT, UK. [2] International Master Program of Agriculture, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung 40227, Taiwan. ; Universite Paul Sabatier CNRS, UMR 5174 Evolution et Diversite Biologique, Batiment 4R1, 31062 Toulouse, France. ; Northeast Region Inventory and Monitoring Program, National Park Service, 120 Chatham Lane, Fredericksburg, Virginia 22405, USA. ; Andes to Amazon Biodiversity Program, Puerto Maldonado, Madre de Dios, Peru. ; Universidade Federal do Para, Centro de Geociencias, Belem, CEP 66017-970 Para, Brazil. ; Universidade do Estado de Mato Grosso, Campus de Nova Xavantina, Caixa Postal 08, CEP 78.690-000, Nova Xavantina MT, Brazil. ; Department of Anthropology, University of Texas at Austin, SAC Room 5.150, 2201 Speedway Stop C3200, Austin, Texas 78712, USA. ; Department of Entomology, Smithsonian Institution, PO Box 37012, MRC 187, Washington DC 20013-7012, USA. ; Cirad, UMR Ecologie des Forets de Guyane, Campus Agronomique, 97310 Kourou, French Guiana. ; 1] School of Geography, University of Leeds, Leeds LS2 9JT, UK. [2] Instituto de Investigaciones de la Amazonia Peruana, Av. A. Jose Quinones km 2.5, Iquitos, Peru. ; World Wildlife Fund, 1250 24th Street NW, Washington DC 20037, USA. ; Centre for Tropical Environmental and Sustainability Science (TESS) and School of Marine and Environmental Sciences, James Cook University, Cairns, Queensland 4878, Australia. ; Instituto Boliviano de Investigacion Forestal, C.P. 6201, Santa Cruz de la Sierra, Bolivia. ; National Institute for Research in Amazonia (INPA), C.P. 478, Manaus, Amazonas, CEP 69011-970, Brazil. ; 1] FOMABO, Manejo Forestal en las Tierras Tropicales de Bolivia, Sacta, Bolivia. [2] Escuela de Ciencias Forestales (ESFOR), Universidad Mayor de San Simon (UMSS), Sacta, Bolivia. ; Universidad Estatal Amazonica, Facultad de Ingenieria Ambiental, Paso lateral km 2 1/2 via Napo, Puyo, Pastaza, Ecuador. ; National Institute for Research in Amazonia (INPA), C.P. 2223, 69080-971, Manaus, Amazonas, Brazil. ; Universidad Autonoma del Beni, Campus Universitario, Av. Ejercito Nacional, Riberalta, Beni, Bolivia. ; 1] Instituto Boliviano de Investigacion Forestal, C.P. 6201, Santa Cruz de la Sierra, Bolivia. [2] Forest Ecology and Forest Management Group, Wageningen University, PO Box 47, 6700 AA Wageningen, The Netherlands. ; 1] Center for Tropical Conservation, Duke University, Box 90381, Durham, North Carolina 27708, USA. [2] The Field Museum, 1400 South Lake Shore Drive, Chicago, Illinois 60605-2496, USA. ; Forest Ecology and Forest Management Group, Wageningen University, PO Box 47, 6700 AA Wageningen, The Netherlands. ; Universidad Nacional de la Amazonia Peruana, Iquitos, Loreto, Peru. ; Instituto de Investigaciones para el Desarrollo Forestal (INDEFOR), Universidad de Los Andes, Facultad de Ciencias Forestales y Ambientales, Conjunto Forestal, C.P. 5101, Merida, Venezuela. ; Iwokrama International Centre for Rainforest Conservation and Development, 77 High Street Kingston, Georgetown, Guyana. ; Museu Paraense Emilio Goeldi, Av. Magalhaes Barata, 376 - Sao Braz, CEP 66040-170, Belem PA, Brazil. ; UFRA, Av. Presidente Tancredo Neves 2501, CEP 66.077-901, Belem, Para, Brazil. ; Museu Universitario, Universidade Federal do Acre, Rio Branco AC 69910-900, Brazil. ; European Commission - DG Joint Research Centre, Institute for Environment and Sustainability, Via Enrico Fermi 274, 21010 Ispra, Italy. ; 1] Naturalis Biodiversity Center, PO Box, 2300 RA, Leiden, The Netherlands. [2] Ecology and Biodiversity Group, Utrecht University, PO Box 80084, 3508 TB Utrecht, The Netherlands. ; Museo de Historia Natural Alcide D'Orbigny, Av. Potosi no 1458, Cochabamba, Bolivia. ; 1] School of Earth and Environmental Science, James Cook University, Cairns, Queensland 4870, Australia. [2] Centre for Tropical Environmental and Sustainability Science (TESS) and School of Marine and Tropical Biology, James Cook University, Cairns, Queensland 4878, Australia. ; 1] Northumbria University, School of Geography, Ellison Place, Newcastle upon Tyne, Newcastle NE1 8ST, UK. [2] University of Wisconsin, Milwaukee, Wisconsin 53202, USA. [3] Smithsonian Tropical Research Institute, Apartado Postal 0843-03092, Panama, Republic of Panama. ; Van der Hout Forestry Consulting, Jan Trooststraat 6, 3078 HP Rotterdam, The Netherlands. ; Universidade Estadual de Campinas, NEPAM, Rua dos Flamboyants, 155- Cidade Universitaria Zeferino Vaz, Campinas, CEP 13083-867, Sao Paulo, Brazil. ; 1] Universidad Autonoma del Beni, Campus Universitario, Av. Ejercito Nacional, Riberalta, Beni, Bolivia. [2] Centro de Investigacion y Promocion del Campesinado, regional Norte Amazonico, C/ Nicanor Gonzalo Salvatierra N degrees 362, Casilla 16, Riberalta, Bolivia. ; Tropenbos International, PO Box 232, 6700 AE Wageningen, The Netherlands.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25788097" target="_blank"〉PubMed〈/a〉

Description: In prokaryotes, genome size is associated with metabolic versatility, regulatory complexity, effective population size, and horizontal transfer rates. We therefore analyzed the covariation of genome size and operon conservation to assess the evolutionary models of operon formation and maintenance. In agreement with previous results, intraoperonic pairs of essential and of highly expressed genes are more conserved. Interestingly, intraoperonic pairs of genes are also more conserved when they encode proteins at similar cell concentrations, suggesting a role of cotranscription in diminishing the cost of waste and shortfall in gene expression. Larger genomes have fewer and smaller operons that are also less conserved. Importantly, lower conservation in larger genomes was observed for all classes of operons in terms of gene expression, essentiality, and balanced protein concentration. We reached very similar conclusions in independent analyses of three major bacterial clades (α- and β-Proteobacteria and Firmicutes). Operon conservation is inversely correlated to the abundance of transcription factors in the genome when controlled for genome size. This suggests a negative association between the complexity of genetic networks and operon conservation. These results show that genome size and/or its proxies are key determinants of the intensity of natural selection for operon organization. Our data fit better the evolutionary models based on the advantage of coregulation than those based on genetic linkage or stochastic gene expression. We suggest that larger genomes with highly complex genetic networks and many transcription factors endure weaker selection for operons than smaller genomes with fewer alternative tools for genetic regulation.

Description: Stellar intensity interferometers will achieve stellar imaging with a tenth of a milli-arcsecond resolution in the optical band by taking advantage of the large light collecting area and broad range of intertelescope distances offered by future gamma-ray Air Cherenkov Telescope (ACT) arrays. Up to now, studies characterizing the capabilities of intensity interferometers using ACTs have not accounted for realistic effects such as telescope mirror extension, detailed photodetector time response, excess noise and night sky contamination. In this paper, we present the semiclassical quantum optics Monte Carlo simulation we developed in order to investigate these experimental limitations. In order to validate the simulation algorithm, we compare our first results to models for sensitivity and signal degradation resulting from mirror extension, pulse shape, detector excess noise and night sky contamination.

Description: Optical interferometry has been successful at achieving milliarcsecond resolution on bright stars. Imaging performance can improve greatly by increasing the number of baselines, which has motivated proposals to build large (~100 m) optical interferometers with tens to hundreds of telescopes. It is also desirable to adaptively correct atmospheric turbulence to obtain direct phased images of astrophysical sources. When a natural guide star is not available, we investigate the feasibility of using a modified laser-guide-star technique that is suitable for large diluted apertures. The method consists of using subsets of apertures to create an array of artificial stars in the sodium layer and collecting back-scattered light with the same subapertures. We present some numerical and laboratory simulations that quantify the requirements and sensitivity of the technique.

Description: Future large arrays of telescopes, used as intensity interferometers, can be used to image the surfaces of stars with unprecedented angular resolution. Fast-rotating, hot stars are particularly attractive targets for intensity interferometry since shorter (blue) wavelength observations do not pose additional challenges. Starting from realistic surface brightness simulations of fast-rotating stars, we discuss the capabilities of future intensity interferometers for imaging effects such as gravity darkening and rotational deformation. We find that two-telescope intensity correlation data allow reasonably good imaging of these phenomena, but can be improved with additional higher order (e.g. three-telescope) correlation data, which contain some Fourier phase information.