Ab-initio calculations of the proton location in topaz-OH, Al2SiO4(OH)2

The position of hydrogen in the structure of topaz-OH was determined by means of ab-initio quantum-mechanic calculations. Static lattice energy calculations predict the existence of four non-equivalent positions of protons, which are characterized by O4-H1... O1, O4-H2... O2, O4-H3... O3 and O4-H4... O4 hydrogen bonds. The distribution of the protons between positions of local equilibrium is controlled by the proton-proton avoidance rule and the strength of the hydrogen bonds. The most favourable configuration of hydrogen atoms is achieved for adjacent protons, which form O4-H3... O3 and O4-H4... O4 hydrogen bonds, respectively. The thermal excitation of atoms at a temperature of 55 K is large enough for the hydrogen atoms occasionally to change their positions to form O4-H1... O1 and O4-H2... O2 bonds. At ambient pressures and higher temperatures the protons are in a dynamic exchange between the allowed positions of local minima. As a consequence, for nearly room-temperature conditions, the dynamic change between different structural configurations leads to the violation of all possible symmetry elements and with that to space group #E5/E5#1. The flipping of the protons between different sites is achieved by simple rotation of the OH-dipole and does not produce any significant distortion of the framework of topaz, whose symmetry remains that of the space group Pbnm. Therefore, no reduction of symmetry has been observed in former X-ray studies on topaz-OH. Calculated IR absorption spectra of topaz-OH were found to be in good agreement with measured spectra. According to the calculations, the two favourable configurations of protons might correspond to the measured peak splitting within the OH-stretching range. An experimentally observed low-frequency band at 3520 cm−1 was assigned to the OH-stretching of the O4-H3... O3 bond, while the band at 3600 cm−1 was attributed to OH-stretching of the O4-H4... O4 hydrogen bond. The broad peak in FAR-IR frequency range at 100-150 cm−1 is attributed to the stretching of H3... O3 and H4... O4 contacts. The rate of proton exchange at 670 K among different sites was estimated by ab-inito molecular dynamic simulations. The calculations predict that flipping of adjacent protons between O4-H3... O3 and O4-H4... O4 bonds at 670 K occur at a rate of about 1.96 TH

The dynamics of solo self-employment: Persistence and transition to employership

This study examines dynamics of solo self-employment. In particular, we investigate the extent of true state dependence and cross state dependence, i.e., whether experiencing solo self-employment causally affects the probability of becoming an employer in the future. We use data from the German Socio-Economic Panel to estimate dynamic multinomial logit models. Our results show that the extent of true (cross) state dependence is rather small. The observed persistence in solo self-employment as well as transitions from solo self-employment to employership can largely be explained by observed and unobserved heterogeneity.Diese Studie untersucht die Dynamik der Solo-Selbständigkeit (Verbleib,Zu- und Abgänge). Wir berechnen das Ausmaß genuiner Zustandsabhängigkeit für den Verbleib in Solo-Selbständigkeit und schätzen den kausalen Effekt der Solo-Selbstständigkeit auf die Wahrscheinlichkeit, Arbeitgeber zu werden. Die Berechungen basieren auf dynamischen multinomialen Logit-Modellen, die mit Daten des Sozio-oekonomischen Panels geschätzt wurden. Unsere Ergebnisse deuten auf eine nur geringe genuine Zustandsabhängigkeit hin: Sowohl die beobachtete Persistenz in Solo-Selbständigkeit als auch die Übergänge zum Arbeitgeber-Status lassen sich größtenteils durch (beobachtete und unbeobachtete) individuelle Merkmale erklären

Development of consumption-based land use indicators

With this UFOPLAN project on land use indicators, the German Federal Environment Agency aimed at further developing indicators from a consumption perspective in support of Germany’s sustainability strategy, covering both area-based and impact-oriented land footprint indicators.The project also aimed at calculating selected land footprint indicators for Germany and the EU. These indicators should provide an improved understanding of the global teleconnections of consumption and land use relevant for policy making towards achieving sustainable land use. This synthesis report presents the key results from this project. First, we present a structured overview of existing approaches for estimating land footprintsand describe their technical and structural characteristicsas well as their strengths and weaknesses. This leads to the specification of a hybrid methodology as the preferred calculation approach. In the second part, we present the developed innovative hybrid land footprint method, consisting of a global land flow accounting and trade model capturing commodity flows in physical units to track embodied land along global supply chains. For non-food commodities the supply chains were complemented by an environmental input-output model. This method was used to calculate the cropland, grassland and forestland footprint of Germany and the EU. Finally, an overview of existing indicator systems for representing the environmental impacts of land use was provided and their complementary usage to extend area-based land footprints was discussed. A few of these complementary indicators were also quantified, most notably the deforestation footprint. The synthesis report closes with an overview of the thematic areas that need to be addressed in future research

Hope for Bohemian ecologists – comments on “A possible role of social activity to explain differences in publication output among ecologists?” by Tomáš Grim, Oikos 2008

No abstract available

Spatial patterns of carbon, biodiversity, deforestation threat, and REDD+ projects in Indonesia

There are concerns that Reduced Emissions from Deforestation and forest Degradation (REDD+) may fail to deliver potential biodiversity cobenefits if it is focused on high carbon areas. We explored the spatial overlaps between carbon stocks, biodiversity, projected deforestation threats, and the location of REDD+ projects in Indonesia, a tropical country at the forefront of REDD+ development. For biodiversity, we assembled data on the distribution of terrestrial vertebrates (ranges of amphibians, mammals, birds, reptiles) and plants (species distribution models for 8 families). We then investigated congruence between different measures of biodiversity richness and carbon stocks at the national and subnational scales. Finally, we mapped active REDD+ projects and investigated the carbon density and potential biodiversity richness and modeled deforestation pressures within these forests relative to protected areas and unprotected forests. There was little internal overlap among the different hotspots (richest 10% of cells) of species richness. There was also no consistent spatial congruence between carbon stocks and the biodiversity measures: a weak negative correlation at the national scale masked highly variable and nonlinear relationships island by island. Current REDD+ projects were preferentially located in areas with higher total species richness and threatened species richness but lower carbon densities than protected areas and unprotected forests. Although a quarter of the total area of these REDD+ projects is under relatively high deforestation pressure, the majority of the REDD+ area is not. In Indonesia at least, first-generation REDD+ projects are located where they are likely to deliver biodiversity benefits. However, if REDD+ is to deliver additional gains for climate and biodiversity, projects will need to focus on forests with the highest threat to deforestation, which will have cost implications for future REDD+ implementation

Using ocean models to predict spatial and temporal variation in marine carbon isotopes

Natural-abundance stable isotope ratios provide a wealth of ecological information relating to food web structure, trophic level, and location. The correct interpretation of stable isotope data requires an understanding of spatial and temporal variation in the isotopic compositions at the base of the food web. In marine pelagic environments, accurate interpretation of stable isotope data is hampered by a lack of reliable, spatio-temporally distributed measurements of baseline isotopic compositions. In this study, we present a relatively simple, process-based carbon isotope model that predicts the spatio-temporal distributions of the carbon isotope composition of phytoplankton (here expressed as δ13CPLK) across the global ocean at one degree and monthly resolution. The model is driven by output from a coupled physics-biogeochemistry model, NEMO-MEDUSA, and operates offline; it could also be coupled to alternative underlying ocean model systems. Model validation is challenged by the same lack of spatio-temporally explicit data that motivates model development, but predictions from our model successfully reproduce major spatial patterns in carbon isotope values observed in zooplankton, and are consistent with simulations from alternative models. Model predictions represent an initial hypothesis of spatial and temporal variation in carbon isotopic baselines in ocean areas where a few data are currently available, and provide the best currently available tool to estimate spatial and temporal variation in baseline isotopic compositions at ocean basin to global scales

Molecular imaging: novel tools in visualizing rheumatoid arthritis

Molecular imaging is a rapidly emerging field in biomedical research, aiming at the visualization, characterization and quantification of molecular and cellular processes non-invasively within intact living organisms. To sense biological processes such as gene expression, angiogenesis, apoptosis or cell trafficking in vivo, imaging reporter agents that interact specifically with molecular targets and appropriate imaging systems are currently under development. In rheumatoid arthritis, these novel tools will be used to evaluate physiological and pathophysiological processes, to facilitate diagnosis and monitor therapeutic regimens, to enable reliable prognosis and to support the development of new therapies. In this review, we summarize the basic principles of molecular imaging, such as the development of molecular imaging agents, the actual capabilities of different imaging modalities and the most recent advances in molecular imaging, demonstrating the potential of this technology. With regard to their applicability in rheumatic diseases, we discuss potential molecular targets, current experimental approaches and the future prospects for molecular imaging in rheumatoid arthriti

Protecting biodiversity and economic returns in resource-rich tropical forests.

In pursuit of socioeconomic development, many countries are expanding oil and mineral extraction into tropical forests. These activities seed access to remote, biologically rich areas, thereby endangering global biodiversity. Here we demonstrate that conservation solutions that effectively balance the protection of biodiversity and economic revenues are possible in biologically valuable regions. Using spatial data on oil profits and predicted species and ecosystem extents, we optimise the protection of 741 terrestrial species and 20 ecosystems of the Ecuadorian Amazon, across a range of opportunity costs (i.e. sacrifices of extractive profit). For such an optimisation, giving up 5% of a year's oil profits (US$221 million) allows for a protected area network that retains of an average of 65$ 1.7 billion), and uses only marginally less land, to achieve equivalent levels of ecological protection. Applying spatial statistics to remotely sensed, historic deforestation data, we further focus the optimisation to areas most threatened by imminent forest loss. We identify Emergency Conservation Targets: areas that are essential to a cost-effective conservation reserve network and at imminent risk of destruction, thus requiring urgent and effective protection. Governments should employ the methods presented here when considering extractive led development options, to responsibly manage the associated ecological-economic trade-offs and protect natural capital. Article Impact Statement: Governments controlling resource extraction from tropical forests can arrange production and conservation to retain biodiversity and profits. This article is protected by copyright. All rights reserved

Symptoms and their Relationship to Disability Following Treatment for Lower Extremity Tumours

Purpose. The aims of this study were to describe the symptoms experienced by patients in the first year following treatment for lower extremity sarcoma by limb conservation and to describe the relationship between symptoms and physical disability