University of Vienna

About: University of Vienna is a education organization based out in Vienna, Austria. It is known for research contribution in the topics: Population & Stars. The organization has 44686 authors who have published 95840 publications receiving 2907492 citations.

Biomarkers for In Situ Detection of Anaerobic Ammonium-Oxidizing (Anammox) Bacteria

Abstract: The existence of anaerobic ammonium oxidation (anammox) was hypothesized based on nutrient profiles and thermodynamic calculations (5, 31, 44). It was first discovered about 1 decade ago (25) in a pilot plant treating wastewater from a yeast-producing company in Delft, The Netherlands. The anammox reaction is the oxidation of ammonium under anoxic conditions with nitrite as the electron acceptor and dinitrogen gas as the product. Hydroxylamine and hydrazine were identified as important intermediates (51). Due to their very low growth rates (doubling time in enrichments is at best 11 days) the cultivation of the anammox bacteria proved to be tedious and required very efficient biomass retention (41, 43). A physical purification of anammox organisms from enrichment cultures was achieved with percoll density centrifugation (42). The purified cells performed the anammox reaction after activation by hydrazine. Based on phylogenetic analysis, the discovered anammox organism branched deep in the Planctomycetes phylum (Fig. 1A and B, [42]) and was named “Candidatus Brocadia anammoxidans” (19). FIG. 1. (A) 16S rRNA gene-based phylogenetic tree reflecting the relationship of “Ca. Scalindua,” “Ca. Brocadia,” and “Ca. Kuenenia” to other Planctomycetes and other reference organisms. Tree reconstruction was ... After the first discovery, nitrogen losses, which could only be explained by the anammox reaction, were reported in other wastewater treatment facilities including landfill leachate treatment plants in Germany, Switzerland, and England (11, 14, 15, 36), as well as in semitechnical wastewater treatment plants in Germany (34), Belgium (30), Japan (12), Australia (48), and the United States (10, 45). Molecular techniques showed the presence of organisms affiliated with the anammox branch within the Planctomycetes in all these wastewater treatment plants. Nutrient profiles and 15N tracer studies in suboxic marine and estuarine environments indicated that anammox is also a key player in the marine nitrogen cycle (8, 46, 49). In addition, 16S rRNA gene analysis, fluorescence in situ hybridization (FISH), the distribution of specific anammox membrane lipids, nutrient profiles, and tracer experiments with [15N]ammonia showed the link between the anammox reaction and the occurrence of the anammox bacterium “Candidatus Scalindua sorokinii” in the suboxic zone of the Black Sea (20). The anammox reaction has also been tested for implementation for full-scale removal of ammonia in wastewater treatment (13, 52, 53). The detection and identification of active anammox organisms in environmental samples combined with information on environmental conditions can facilitate the search for possible biomass sources to be used as an inoculum for laboratory, semitechnical, or full-scale anammox reactors. Additionally, such information could provide insights into the niche differentiation of anammox organisms. This review summarizes the recent advances made in the 16S rRNA gene-based techniques for the detection of anammox bacteria. A convenient PCR detection method for anammox organisms is presented in which anammox-specific FISH probes were used as primers. Furthermore, methods which link activity and the detection of anammox bacteria, such as the combination of FISH and microautoradiography (FISH-MAR) (22) as well as FISH targeting the intergenic spacer region (ISR) between the 16S and 23S rRNA are discussed and compared to conventional methods to detect anammox activity. Each of these approaches by itself only addresses limited aspects, such as abundance, activity, or physiology. Thus, a combination of rRNA-based and non-rRNA-based methods is necessary to allow a comprehensive study of anammox bacteria in their ecosystems.

Newton-X: a surface-hopping program for nonadiabatic molecular dynamics

Abstract: The Newton-X program is a general-purpose program package for excited-state molecular dynamics, including nonadiabatic methods. Its modular design allows Newton-X to be easily linked to any quantum-chemistry package that can provide excited-state energy gradients. At the current version, Newton-X can perform nonadiabatic dynamics using Columbus, Turbomole, Gaussian, and Gamess program packages with multireference configuration interaction, multiconfigurational self-consistent field, time-dependent density functional theory, and other methods. Nonadiabatic dynamics simulations with a hybrid combination of methods, such as Quantum-Mechanics/Molecular-Mechanics, are also possible. Moreover, Newton-X can be used for the simulation of absorption and emission spectra. The code is distributed free of charge for noncommercial and nonprofit uses at www.newtonx.org. WIREs Comput Mol Sci 2014, 4:26–33. doi: 10.1002/wcms.1158 The authors have declared no conflicts of interest in relation to this article. For further resources related to this article, please visit the WIREs website.

What have we learned from three decades of research on the productivity of public capital

Abstract: The last three decades have witnessed a great deal of research effort devoted to measuring the private output elasticity of public capital. The wide range of available estimates have precluded any consensus so far, however. This paper reconciles the empirical findings of the literature by quantitatively analyzing a sample of 578 estimates collected from 68 studies for the 1983–2008 period. Using meta-regression analysis, we show how study design characteristics and publication bias can explain a large fraction of the variation across estimates. We find a short-run output elasticity of public capital supplied at the central government level of 0.083, which increases to 0.122 in the long run. If, in addition, only core infrastructure at a regional/local level of government is considered, these estimates are almost doubled. The average output elasticity of public capital amounts to 0.106. Our results suggest that public capital is undersupplied in OECD economies.

Global rise in emerging alien species results from increased accessibility of new source pools.

Abstract: Our ability to predict the identity of future invasive alien species is largely based upon knowledge of prior invasion history Emerging alien species—those never encountered as aliens before—therefore pose a significant challenge to biosecurity interventions worldwide Understanding their temporal trends, origins, and the drivers of their spread is pivotal to improving prevention and risk assessment tools Here, we use a database of 45,984 first records of 16,019 established alien species to investigate the temporal dynamics of occurrences of emerging alien species worldwide Even after many centuries of invasions the rate of emergence of new alien species is still high: One-quarter of first records during 2000–2005 were of species that had not been previously recorded anywhere as alien, though with large variation across taxa Model results show that the high proportion of emerging alien species cannot be solely explained by increases in well-known drivers such as the amount of imported commodities from historically important source regions Instead, these dynamics reflect the incorporation of new regions into the pool of potential alien species, likely as a consequence of expanding trade networks and environmental change This process compensates for the depletion of the historically important source species pool through successive invasions We estimate that 1–16% of all species on Earth, depending on the taxonomic group, qualify as potential alien species These results suggest that there remains a high proportion of emerging alien species we have yet to encounter, with future impacts that are difficult to predict