Large lianas as hyperdynamic elements of the tropical forest canopy

Lianas (woody vines) are an important component of lowland tropical forests. We report large liana and tree inventory and dynamics data from Amazonia over periods of up to 24 years, making this the longest geographically extensive study of liana ecology to date. We use these results to address basic questions about the ecology of large lianas in mature forests and their interactions with trees. In one intensively studied site we find that large lianas (≥10 cm diameter) represent ,5% of liana stems, but 80% of biomass of well-lit upper canopy lianas. Across sites, large lianas and large trees are both most successful in terms of structural importance in richer soil forests, but large liana success may be controlled more by the availability of large tree supports rather than directly by soil conditions. Long-term annual turnover rates of large lianas are 5–8%, three times those of trees. Lianas are implicated in large tree mortality: liana-infested large trees are three times more likely to die than liana-free large trees, and large lianas are involved in the death of at least 30% of tree basal area. Thus large lianas are a much more dynamic component of Amazon forests than are canopy trees, and they play a much more significant functional role than their structural contribution suggests

Thermal Decomposition Of [m3(co)12] (m = Ru, Os) Physisorbed Onto Porous Vycor Glass: A Route To A Glass/ruo2 Nanocomposite

This paper reports the preparation and characterization of oxide/glass nanocomposites, obtained by the impregnation and thermal decomposition of the trinuclear metal carbonyl clusters[M3(CO)12] (M = Ru, Os) inside the pores of porous Vycor glass (PVG). The intermediate species formed during the thermal treatment of the [M3(CO)12] adsorbed PVG materials were studied by UV-VIS-NIR and diffuse reflectance infrared (DR-IR) spectroscopy. At 65°C (M-Ru) and 110°C (M = Os), formation of surface bound [HM3(CO)10(μ- OSi≃)] species occurs, as a result of oxidative addition of a PVG surface silanol group to a cluster M-M bond. At T > 130°C (M = Ru) and T > 200°C (M = Os) cluster breakdown is observed, with formation of [M(CO)(n)(OSi≃)2] (n = 2 and/or 3) species. When [Ru3(CO)12] incorporated PVG is heated in air at T >250°C, decomposition of the cluster and formation of RuO2 nanoparticles are observed. AT 1200 °C, collapse of the glass pores leads to the formation of a transparent silica glass/RuO2 nanocomposite of particle average size 45 Å.92519523Borreli, N.F., Morse, D.L., (1983) Appl. Phys. Lett., 43, p. 1Borreli, N.F., Morse, D.L., Schreus, J.W.H., (1983) J. Appl. Phys., 54, p. 3344Simon, R., Gafney, H.D., (1983) Inorg. Chem., 22, p. 573Darsillo, M.S., Gafney, H.D., Paquete, M.S., (1987) J. Am. Chem. Soc., 109, p. 3275Simon, R.C., Gafney, H.D., Morse, D.L., (1985) Inorg. Chem., 24, p. 2565Gafney, H.D., (1990) J. Macromol. Sci-Chem. A, 27, p. 1187Sunil, D., Sokolov, J., Rafailovich, M.H., Duan, X., Gafney, H.D., (1993) Inorg. Chem., 32, p. 4489Mendoza, E.A., Wolkow, E., Sunil, D., Wong, P., Sobokov, J., Rafailovich, M.H., DeuBoer, M., Gafney, H.D., (1991) Langmuir, 7, p. 3046Sunil, D., Sokolov, J., Rafailovich, M.H., Kotyuzhanskii, B., Gafney, H.D., Wilkens, B.J., Harson, A.L., (1993) J. Appl. Phys., 74, p. 3768Gafney, H.D., Xu, S.P., (1995) Inorg. Chim. Acta., 240, p. 645Luong, J.C., (1988) Superlatt. Microstruct., 4, p. 385Wang, Y., Herron, N., (1991) Res. Chem. Interm., 15, p. 17Stramel, R.D., Nakamura, T., Thomas, J.K., (1988) J. Chem. Soc., Faraday Trans, 1, 84, p. 1287Hendershot, D.G., Gaskill, D.K., Justus, B.L., Fatemi, M., Berry, A.D., (1993) Appl. Phys. Lett., 63, p. 3324Luong, J.C., Borreli, N.F., (1989) Mater. Res. Soc. Symp. Proc., 114, p. 695Justos, B.L., Tonucci, R., Berry, A.D., (1992) Appl. Phys. Lett., 61, p. 3151Dvorak, M.D., Justus, B.L., Gaskill, D.K., Hendershot, D.G., (1995) Appl. Phys. Lett., 66, p. 804Yamashita, H., Ichihashi, Y., Harada, M., Stewart, G., Fox, M.A., Anpo, M., (1996) J. Catal., 158, p. 97Elmer, T.H., Holland, H.J., (1987) Am. Ceram. Soc. Bull., 66, p. 1265Huston, A.L., Justus, B.L., Johnson, T.L., (1996) Appl. Phys. Lett., 68, p. 3327Ozin, G.A., (1992) Adv. Mater., 4, p. 612Wang, Y., Herron, N., (1987) J. Phys. Chem., 91, p. 5005Brus, L., (1986) J. Phys. Chem., 90, p. 2555Steigerwald, M.L., Brus, L.E., (1990) Acc. Chem. Res., 23, p. 183Weller, H., (1996) Angew. Chem., Int. Ed. Engl., 35, p. 1079Wang, Y., Herron, N., Mahler, W., Suna, A., (1989) J. Opt. Soc. Am. B, 6, p. 4Cao, G., Rabenberg, L.K., Numm, C.M., Mallouk, T.E., (1991) Chem. Mater., 3, p. 149Murray, C.B., Norris, D.J., Bawendi, M.G., (1993) J. Am. Chem. Soc., 115, p. 8706Carpenter, J.P., Lukehart, C.M., Henderson, D.O., Mu, R., Jones, B.D., Glosser, R., Stock, S.R., Zhu, J.G., (1996) Chem. Mater., 8, p. 1268Hagfeldt, A., Gratzel, M., (1995) Chem. Rev., 95, p. 49MacDougall, J.E., Eckert, H., Stucky, G.D., Herron, N., Wang, Y., Moller, K., Bein, T., Cox, D., (1989) J. Am. Chem. Soc., 111, p. 8006Watzke, H.J., Fendler, J.H., (1987) J. Phys. Chem., 91, p. 854Giannelis, E.P., (1996) Adv. Mater., 8, p. 29Gehr, R.J., Boyd, R.W., (1996) Chem. Mater., 8, p. 1807Judeinstein, P., Sanchez, C., (1996) J. Mater. Chem., 6, p. 511Corning glass work (1979) Mater. Eng., 90, p. 92Levitz, P., Ehret, G., Sinha, S.K., Drake, J.M., (1991) J. Chem. Phys., 95, p. 6151Gafney, H.D., (1990) Coord. Chem. Rev., 104, p. 113Law, M.J.D., Ramasubramanian, N., (1966) J. Phys. Chem., 70, p. 2740Fan, J., Gafney, H.D., (1994) J. Phys. Chem., 98, p. 13058Gates, B.C., Guczi, L., Knözinger, H., (1996) Metal Clusters in Catalysis, , Elsevier Science Publishing, New YorkMoskovits, M., (1996) Metal Clusters, , Wiley-Interscience Publishing, New YorkMingos, D.M.P., Wales, D.J., (1990) Introduction to Cluster Chemistry, , Prentice Hall, Englewood Cliffs, NJBarth, R., Gates, B.C., Zhao, Y., Knözinger, H., Hulse, J., (1983) J. Catal., 82, p. 147Psaro, R., Ugo, R., Zanderighi, G.M., Besson, B., Smith, A.K., Basset, J.M., (1981) J. Organomet. Chem., 213, p. 215Asakura, K., Yamada, M., Iwasawa, Y., Kuroda, H., (1985) Chem. Lett., p. 511Knözinger, H., Zhao, Y., (1981) J. Catal., 71, p. 337Smith, A.K., Besson, B., Basset, J.M., Psaro, R., Fusi, A., Ugo, R., (1980) J. Organomet. Chem., 192, pp. C31Alexiev, V.D., Binsted, N., Evans, J., Greaves, G.N., Price, R.J., (1987) J. Chem. Soc., Chem. Commun., p. 395Deeba, M., Gates, B.C., (1981) J. Catal., 67, p. 303Theolier, A., Choplin, A., D'Ornelas, L., Basset, J.-M., (1983) Polyhedron, 2, p. 119Walter, T.H., Frauenhoff, G.R., Shapley, J.R., Oldfield, E., (1991) Inorg. Chem., 30, p. 4732Besson, B., Moraweck, B., Smith, K., Basset, J.M., (1980) J. Chem. Soc., Chem. Commun., p. 569Wade, W.H., (1974) Soc. Petroleum Eng. J., p. 139Straley, C., Matteson, A., Feng, S., Schwartz, L.M., Kenyon, W.E., Banavar, J.R., (1989) Appl. Phys. Lett., 51, p. 1146Okubo, T., Inoue, H., (1987) J. Chem. Eng. Jpn., 20, p. 590Tyler, D.R., Levenson, R.A., Gray, H.B., (1978) J. Am. Chem. Soc., 100, p. 7888Huang, Y.S., Pollak, F.H., (1982) Solid State Commun., 43, p. 92

Efficient plot-based floristic assessment of tropical forests

The tropical flora remains chronically understudied and the lack of floristic understanding hampers ecological research and its application for large-scale conservation planning. Given scarce resources and the scale of the challenge there is a need to maximize the efficiency of both sampling strategies and sampling units, yet there is little information on the relative efficiency of different approaches to floristic assessment in tropical forests. This paper is the first attempt to address this gap. We repeatedly sampled forests in two regions of Amazonia using the two most widely used plot-based protocols of floristic sampling, and compared their performance in terms of the quantity of floristic knowledge and ecological insight gained scaled to the field effort required. Specifically, the methods are assessed first in terms of the number of person-days required to complete each sample (‘effort’), secondly by the total gain in the quantity of floristic information that each unit of effort provides (‘crude inventory efficiency’), and thirdly in terms of the floristic information gained as a proportion of the target species pool (‘proportional inventory efficiency’). Finally, we compare the methods in terms of their efficiency in identifying different ecological patterns within the data (‘ecological efficiency’) while controlling for effort. There are large and consistent differences in the performance of the two methods. The disparity is maintained even after accounting for regional and site-level variation in forest species richness, tree density and the number of field assistants. We interpret our results in the context of selecting the appropriate method for particular research purposes

Changes in growth of tropical forests: evaluating potential biases

Over the past century almost every ecosystem on Earth has come under the influence of changes in atmospheric composition and climate caused by human activity. Tropical forests are among the most productive and extensive ecosystems, and it has been hypothesized that both the dynamics and biomass of apparently undisturbed, old-growth tropical forests have been changing in response to atmospheric changes. Long-term forest sample plots are a critical tool in detecting and monitoring such changes, and our recent analysis of pan-tropical-forest plot data has suggested that the biomass of tropical forests has been increasing, providing a modest negative feedback on the rate of accumulation of atmospheric CO2. However, it has been argued that some of these old forest plot data sets have significant problems in interpretation because of the use of nonstandardized methodologies. In this paper we examine the extent to which potential field methodological errors may bias estimates of total biomass change by detailed examination of tree-by-tree records from up to 120 Neotropical plots to test predictions from theory. Potential positive biases on measurements of biomass change include a bias in site selection, tree deformities introduced by the measurement process, poor methodologies to deal with tree deformities or buttresses, and nonrecording of negative growth increments. We show that, while it is important to improve and standardize methodologies in current and future forest-plot work, any systematic errors introduced by currently identified biases in past studies are small and calculable. We conclude that most tropical-forest plot data are of useful quality, and that the evidence does still weigh conclusively in favor of a recent increase of biomass in old-growth tropical forests

An international network to monitor the structure, composition and dynamics of Amazonian forests (RAINFOR)

The Amazon basin is likely to be increasingly affected by environmental changes: higher temperatures, changes in precipitation, CO2 fertilization and habitat fragmentation. To examine the important ecological and biogeochemical consequences of these changes, we are developing an international network, RAINFOR, which aims to monitor forest biomass and dynamics across Amazonia in a co-ordinated fashion in order to understand their relationship to soil and climate. The network will focus on sample plots established by independent researchers, some providing data extending back several decades. We will also conduct rapid transect studies of poorly monitored regions. Field expeditions analysed local soil and plant properties in the first phase (2001–2002). Initial results suggest that the network has the potential to reveal much information on the continental-scale relations between forest and environment. The network will also serve as a forum for discussion between researchers, with the aim of standardising sampling techniques and methodologies that will enable Amazonian forests to be monitored in a coherent manner in the coming decades

ATP5H/KCTD2 locus is associated with Alzheimer's disease risk

To identify loci associated with Alzheimer disease, we conducted a three-stage analysis using existing genome-wide association studies (GWAS) and genotyping in a new sample. In Stage I, all suggestive single-nucleotide polymorphisms (at P<0.001) in a previously reported GWAS of seven independent studies (8082 Alzheimer's disease (AD) cases; 12 040 controls) were selected, and in Stage II these were examined in an in silico analysis within the Cohorts for Heart and Aging Research in Genomic Epidemiology consortium GWAS (1367 cases and 12904 controls). Six novel signals reaching P<5 × 10-6 were genotyped in an independent Stage III sample (the Fundació ACE data set) of 2200 sporadic AD patients and 2301 controls. We identified a novel association with AD in the adenosine triphosphate (ATP) synthase, H+ transporting, mitochondrial F0 (ATP5H)/Potassium channel tetramerization domain-containing protein 2 (KCTD2) locus, which reached genome-wide significance in the combined discovery and genotyping sample (rs11870474, odds ratio (OR)=1.58, P=2.6 × 10 -7 in discovery and OR=1.43, P=0.004 in Fundació ACE data set; combined OR=1.53, P=4.7 × 10 -9). This ATP5H/KCTD2 locus has an important function in mitochondrial energy production and neuronal hyperpolarization during cellular stress conditions, such as hypoxia or glucose deprivation

Seasonal drought limits tree species across the Neotropics

Within the tropics, the species richness of tree communities is strongly and positively associated with precipitation. Previous research has suggested that this macroecological pattern is driven by the negative effect of water-stress on the physiological processes of most tree species. This process implies that the range limits of taxa are defined by their ability to occur under dry conditions, and thus in terms of species distributions it predicts a nested pattern of taxa distribution from wet to dry areas. However, this ‘dry-tolerance’ hypothesis has yet to be adequately tested at large spatial and taxonomic scales. Here, using a dataset of 531 inventory plots of closed canopy forest distributed across the Western Neotropics we investigated how precipitation, evaluated both as mean annual precipitation and as the maximum climatological water deficit, influences the distribution of tropical tree species, genera and families. We find that the distributions of tree taxa are indeed nested along precipitation gradients in the western Neotropics. Taxa tolerant to seasonal drought are disproportionally widespread across the precipitation gradient, with most reaching even the wettest climates sampled; however, most taxa analysed are restricted to wet areas. Our results suggest that the ‘dry tolerance’ hypothesis has broad applicability in the world's most species-rich forests. In addition, the large number of species restricted to wetter conditions strongly indicates that an increased frequency of drought could severely threaten biodiversity in this region. Overall, this study establishes a baseline for exploring how tropical forest tree composition may change in response to current and future environmental changes in this region

Epidemiological trends of HIV/HCV coinfection in Spain, 2015-2019

Altres ajuts: Spanish AIDS Research Network; European Funding for Regional Development (FEDER).Objectives: We assessed the prevalence of anti-hepatitis C virus (HCV) antibodies and active HCV infection (HCV-RNA-positive) in people living with HIV (PLWH) in Spain in 2019 and compared the results with those of four similar studies performed during 2015-2018. Methods: The study was performed in 41 centres. Sample size was estimated for an accuracy of 1%. Patients were selected by random sampling with proportional allocation. Results: The reference population comprised 41 973 PLWH, and the sample size was 1325. HCV serostatus was known in 1316 PLWH (99.3%), of whom 376 (28.6%) were HCV antibody (Ab)-positive (78.7% were prior injection drug users); 29 were HCV-RNA-positive (2.2%). Of the 29 HCV-RNA-positive PLWH, infection was chronic in 24, it was acute/recent in one, and it was of unknown duration in four. Cirrhosis was present in 71 (5.4%) PLWH overall, three (10.3%) HCV-RNA-positive patients and 68 (23.4%) of those who cleared HCV after anti-HCV therapy (p = 0.04). The prevalence of anti-HCV antibodies decreased steadily from 37.7% in 2015 to 28.6% in 2019 (p < 0.001); the prevalence of active HCV infection decreased from 22.1% in 2015 to 2.2% in 2019 (p < 0.001). Uptake of anti-HCV treatment increased from 53.9% in 2015 to 95.0% in 2019 (p < 0.001). Conclusions: In Spain, the prevalence of active HCV infection among PLWH at the end of 2019 was 2.2%, i.e. 90.0% lower than in 2015. Increased exposure to DAAs was probably the main reason for this sharp reduction. Despite the high coverage of treatment with direct-acting antiviral agents, HCV-related cirrhosis remains significant in this population