Towards Large-scale Inconsistency Measurement

We investigate the problem of inconsistency measurement on large knowledge bases by considering stream-based inconsistency measurement, i.e., we investigate inconsistency measures that cannot consider a knowledge base as a whole but process it within a stream. For that, we present, first, a novel inconsistency measure that is apt to be applied to the streaming case and, second, stream-based approximations for the new and some existing inconsistency measures. We conduct an extensive empirical analysis on the behavior of these inconsistency measures on large knowledge bases, in terms of runtime, accuracy, and scalability. We conclude that for two of these measures, the approximation of the new inconsistency measure and an approximation of the contension inconsistency measure, large-scale inconsistency measurement is feasible.Comment: International Workshop on Reactive Concepts in Knowledge Representation (ReactKnow 2014), co-located with the 21st European Conference on Artificial Intelligence (ECAI 2014). Proceedings of the International Workshop on Reactive Concepts in Knowledge Representation (ReactKnow 2014), pages 63-70, technical report, ISSN 1430-3701, Leipzig University, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-15056

Cities on and off the map: A bibliometric assessment of urban globalisation research

Growing out of writings on Global (North) cities, urban globalisation research (UGR) has expanded its canon to engage with an increasing diversity of cities and locations. Yet, this broadening has been uneven and controversial in its theoretical horizons and empirical universe. Focusing on the latter, this paper combines bibliometric, demographic, economic and georeferenced data to assess how UGR maps onto internationally documented cities ( n : 1692). Our study analyses city-themed publications by city location, demographic size and home-country income (2000–2014). Drawing on social science publications indexed in English (Scopus database), our results provide grounds for cautious optimism: recent publications offer broader, though still uneven coverage. The moving spatial average of publication counts also implies that the topical centre of published research gravity is shifting away from Euro-America. Yet, UGR lags in its coverage of the urban geographical universe, failing to keep pace with the economic/demographic trends that are resulting in southward/eastward shifts in worldwide urbanisation. Furthermore, while smaller cities and those in lower-income countries are still sidelined, cities in upper-middle income countries exhibit the largest gaps between observed and expected publication values. In our conclusion, we contend that urban bibliometrics could be further mobilised to identify publication foci and lacunae. Applied to cities on and off the map and a broader universe of urban knowledges, bibliometrics could help move contentious debates forward, identifying newer paradigms that may be engaging the world of cities beyond the globalisation umbrella and charting out multiple and complex topical relations across variegated worlds of urbanism

Volatile hydrocarbons inhibit methanogenic crude oil degradation

Methanogenic degradation of crude oil in subsurface sediments occurs slowly, but without the need for exogenous electron acceptors, is sustained for long periods and has enormous economic and environmental consequences. Here we show that volatile hydrocarbons are inhibitory to methanogenic oil biodegradation by comparing degradation of an artificially weathered crude oil with volatile hydrocarbons removed, with the same oil that was not weathered. Volatile hydrocarbons (nC5-nC10, methylcyclohexane, benzene, toluene, and xylenes) were quantified in the headspace of microcosms. Aliphatic (n-alkanes nC12-nC34) and aromatic hydrocarbons (4-methylbiphenyl, 3-methylbiphenyl, 2-methylnaphthalene, 1-methylnaphthalene) were quantified in the total hydrocarbon fraction extracted from the microcosms. 16S rRNA genes from key microorganisms known to play an important role in methanogenic alkane degradation (Smithella and Methanomicrobiales) were quantified by quantitative PCR. Methane production from degradation of weathered oil in microcosms was rapid (1.1 ± 0.1 μmol CH4/g sediment/day) with stoichiometric yields consistent with degradation of heavier n-alkanes (nC12-nC34). For non-weathered oil, degradation rates in microcosms were significantly lower (0.4 ± 0.3 μmol CH4/g sediment/day). This indicated that volatile hydrocarbons present in the non-weathered oil inhibit, but do not completely halt, methanogenic alkane biodegradation. These findings are significant with respect to rates of biodegradation of crude oils with abundant volatile hydrocarbons in anoxic, sulphate-depleted subsurface environments, such as contaminated marine sediments which have been entrained below the sulfate-reduction zone, as well as crude oil biodegradation in petroleum reservoirs and contaminated aquifers

Planet formation around stars of various masses: Hot super-Earths

We consider trends resulting from two formation mechanisms for short-period super-Earths: planet-planet scattering and migration. We model scenarios where these planets originate near the snow line in ``cold finger'' circumstellar disks. Low-mass planet-planet scattering excites planets to low periastron orbits only for lower mass stars. With long circularisation times, these planets reside on long-period eccentric orbits. Closer formation regions mean planets that reach short-period orbits by migration are most common around low-mass stars. Above ~1 Solar mass, planets massive enough to migrate to close-in orbits before the gas disk dissipates are above the critical mass for gas giant formation. Thus, there is an upper stellar mass limit for short-period super-Earths that form by migration. If disk masses are distributed as a power law, planet frequency increases with metallicity because most disks have low masses. For disk masses distributed around a relatively high mass, planet frequency decreases with increasing metallicity. As icy planets migrate, they shepherd interior objects toward the star, which grow to ~1 Earth mass. In contrast to icy migrators, surviving shepherded planets are rocky. Upon reaching short-period orbits, planets are subject to evaporation processes. The closest planets may be reduced to rocky or icy cores. Low-mass stars have lower EUV luminosities, so the level of evaporation decreases with decreasing stellar mass.Comment: Accepted to ApJ. 13 pages of emulateap

A study of ore genesis and geochronology in the sub-volcanic tin belt of the Eastern Andes, Bolivia

Imperial Users onl

The NASA Astrophysics Data System: Overview

The NASA Astrophysics Data System Abstract Service has become a key component of astronomical research. It provides bibliographic information daily, or near daily, to a majority of astronomical researchers worldwide. We describe the history of the development of the system and its current status. We show several examples of how to use the ADS, and we show how ADS use has increased as a function of time. Currently it is still increasing exponentially, with a doubling time for number of queries of 17 months. Using the ADS logs we make the first detailed model of how scientific journals are read as a function of time since publication. The impact of the ADS on astronomy can be calculated after making some simple assumptions. We find that the ADS increases the efficiency of astronomical research by 333 Full Time Equivalent (2000 hour) research years per year, and that the value of the early development of the ADS for astronomy, compared with waiting for mature technologies to be adopted, is 2332 FTE research years. The ADS is available at http://adswww.harvard.edu/.Comment: 19 pages, 22 figure

Oxidative stress via hydrogen peroxide and menadione does not induce the secretion of IGFBP-5 in primary rat hepatocytes

Conference abstract describing how oxidative stress via hydrogen peroxide and menadione does not induce the secretion of IGFBP-5 in primary rat hepatocytes. Presented at the 2010 annual congress of the british toxicology societ