Composition of woody species in a dynamic forest-woodland-savannah mosaic in Uganda: implications for conservation and management

Forest¿woodland¿savannah mosaics are a common feature in the East African landscape. For the conservation of the woody species that occur in such landscapes, the species patterns and the factors that maintain it need to be understood. We studied the woody species distribution in a forest¿woodland¿savannah mosaic in Budongo Forest Reserve, Uganda. The existing vegetation gradients were analyzed using data from a total of 591 plots of 400 or 500 m2 each. Remotely sensed data was used to explore current vegetation cover and the gradients there in for the whole area. A clear species gradient exists in the study area ranging from forest, where there is least disturbance, to wooded grassland, where frequent fire disturbance occurs. Most species are not limited to a specific part of the gradient although many show a maximum abundance at some point along the gradient. Fire and accessibility to the protected area were closely related to variation in species composition along the ordination axis with species like Cynometra alexandri and Uvariopsis congensis occurring at one end of the gradient and Combretum guenzi and Lonchocarpus laxiflorus at the other. The vegetation cover classes identified in the area differed in diversity, density and, especially, basal area. All vegetation cover classes, except open woodland, had indicator species. Diospyros abyssinica, Uvariopsis congensis, Holoptelea grandis and all Celtis species were the indicator species for the forest class, Terminalia velutina and Albizia grandbracteata for closed woodland, Grewia mollis and Combretum mole for very open woodland and Lonchocarpus laxiflorus, Grewia bicolor and Combretum guenzi for the wooded grassland class. Eleven of the species occurred in all cover classes and most of the species that occurred in more than one vegetation cover class showed peak abundance in a specific cover class. Species composition in the study area changes gradually from forest to savannah. Along the gradient, the cover classes are distinguishable in terms of species composition and vegetation structure. These classes are, however, interrelated in species composition. For conservation of the full range of the species within this East African landscape, the mosaic has to be managed as an integrated whole. Burning should be varied over the area with the forest not being burnt at all and the wooded grassland burnt regularly. The different vegetation types that occur between these two extremes should be maintained using a varied fire regim

Effects of Anacetrapib in Patients with Atherosclerotic Vascular Disease

BACKGROUND: Patients with atherosclerotic vascular disease remain at high risk for cardiovascular events despite effective statin-based treatment of low-density lipoprotein (LDL) cholesterol levels. The inhibition of cholesteryl ester transfer protein (CETP) by anacetrapib reduces LDL cholesterol levels and increases high-density lipoprotein (HDL) cholesterol levels. However, trials of other CETP inhibitors have shown neutral or adverse effects on cardiovascular outcomes. METHODS: We conducted a randomized, double-blind, placebo-controlled trial involving 30,449 adults with atherosclerotic vascular disease who were receiving intensive atorvastatin therapy and who had a mean LDL cholesterol level of 61 mg per deciliter (1.58 mmol per liter), a mean non-HDL cholesterol level of 92 mg per deciliter (2.38 mmol per liter), and a mean HDL cholesterol level of 40 mg per deciliter (1.03 mmol per liter). The patients were assigned to receive either 100 mg of anacetrapib once daily (15,225 patients) or matching placebo (15,224 patients). The primary outcome was the first major coronary event, a composite of coronary death, myocardial infarction, or coronary revascularization. RESULTS: During the median follow-up period of 4.1 years, the primary outcome occurred in significantly fewer patients in the anacetrapib group than in the placebo group (1640 of 15,225 patients [10.8%] vs. 1803 of 15,224 patients [11.8%]; rate ratio, 0.91; 95% confidence interval, 0.85 to 0.97; P=0.004). The relative difference in risk was similar across multiple prespecified subgroups. At the trial midpoint, the mean level of HDL cholesterol was higher by 43 mg per deciliter (1.12 mmol per liter) in the anacetrapib group than in the placebo group (a relative difference of 104%), and the mean level of non-HDL cholesterol was lower by 17 mg per deciliter (0.44 mmol per liter), a relative difference of -18%. There were no significant between-group differences in the risk of death, cancer, or other serious adverse events. CONCLUSIONS: Among patients with atherosclerotic vascular disease who were receiving intensive statin therapy, the use of anacetrapib resulted in a lower incidence of major coronary events than the use of placebo. (Funded by Merck and others; Current Controlled Trials number, ISRCTN48678192 ; ClinicalTrials.gov number, NCT01252953 ; and EudraCT number, 2010-023467-18 .)

Growth and Structure of Cu and Au on the Nonpolar ZnO(101̅0) Surface: STM, XPS, and DFT Studies

The morphology and electronic structure of Cu and Au clusters deposited via thermal evaporation onto ZnO(101̄0) substrates have been studied via scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). The initial stages of nucleation and growth (∼0.2 ML) of both Cu and Au are compared with density functional theory (DFT) calculations, which show an excellent agreement with the cluster morphologies observed by STM, with Cu nucleating three-dimensional (3D) islands even at small coverage while Au nucleates single-layer islands that grow layer by layer. DFT also gives insight into the diffusion behavior of Cu and Au adatoms on the ZnO substrate, showing strongly anisotropic diffusion barriers for Cu atoms which results in the experimentally observed preferential cluster nucleation along [0001] step edges, whereas Au shows no such anisotropy and Au clusters are observed to have no preferred nucleation sites. XPS results show a slight positive charging of the small Cu clusters at 0.2 ML coverage, which disappears at higher coverage. The single-layer Au islands formed at low coverage show some evidence of positive charging as well, which likewise disappears with increasing cluster size. Additionally, the Au clusters show a trend of increasing metallicity as the clusters grow and transition from single-layer islands to 3D structures, demonstrated by the increasing asymmetry in the Au 4f line shape as a function of Au coverage. In general, the observed charge transfer trends are supported by Bader charge analysis. © 2013 American Chemical Society

Time structure of the extensive air shower muon component measured by the KASCADE experiment

The temporal structure of the extensive air shower (EAS) muon component (E-thres = 2.4 GeV) is studied at sea level by measurements of the muon arrival time distributions using the muon detection facilities of the KASCADE central detector. Data have been analysed for EAS core distances up to 110 m for primary energies around the knee region. The time structure of the EAS muon component is represented by the distributions of the mean, median, first quartile and the third quartile of the muon arrival time distributions relative to the foremost muon. The EAS time profiles (variation with the distance from the EAS center) are studied along their dependencies on the angle of incidence and the energy-indicative muon number N-mu(tr). Effects of the fluctuation of the arrival time of the first registered muon are scrutinised and corrected. The experimental results are compared with EAS Monte Carlo (CORSIKA-GEANT) simulations, fully including the detector responses and illustrating the phenomenological features. The comparisons, though generally in fair global agreement, revealed that the simulations underestimate the shower thickness and show nearly no dependence on the mass composition if the time resolution of the apparatus is realistically taken into account. (C) 2001 Elsevier Science B.V. All rights reserved