1,997 research outputs found

    What causes the irregular cycle of the atmospheric tape recorder signal in HCN?

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    Variations in the mixing ratio of long-lived trace gases entering the stratosphere in the tropics are carried upward with the rising air with the signal being observable throughout the tropical lower stratosphere. This phenomenon, referred to as "atmospheric tape recorder" has previously been observed for water vapor, CO2, and CO which exhibit an annual cycle. Recently, based on Microwave Limb Sounder (MLS) and the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) satellite measurements, the tape recorder signal has been observed for hydrogen cyanide (HCN) but with an approximately two-year period. Here we report on a model simulation of the HCN tape recorder for the time period 2002-2008 using the Chemical Lagrangian Model of the Stratosphere (CLaMS). The model can reproduce the observed pattern of the HCN tape recorder signal if time-resolved emissions from fires in Indonesia are used as lower boundary condition. This finding indicates that inter-annual variations in biomass burning in Indonesia, which are strongly influenced by El Nino events, control the HCN tape recorder signal. A longer time series of tropical HCN data will probably exhibit an irregular cycle rather than a regular biannual cycle. Citation: Pommrich, R., R. Muller, J.-U. Grooss, G. Gunther, P. Konopka, M. Riese, A. Heil, M. Schultz, H.-C. Pumphrey, and K. A. Walker (2010), What causes the irregular cycle of the atmospheric tape recorder signal in HCN?, Geophys. Res. Lett., 37, L16805, doi:10.1029/2010GL044056

    Mechanism of imidazolium ionic liquids toxicity in Saccharomyces cerevisiae and rational engineering of a tolerant, xylose-fermenting strain

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    Additional file 3. Fermentation profiles of Y133 and Y133-IIL in the presence of 1 % [BMIM]Cl at pH 6.5 and pH 5.0, and either aerobic or anaerobic conditions (n = 3, Mean ± S.E, except n = 2 for Y133 pH 6.5 anaerobic 72 h)

    Foreign capital in a growth model

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    Within an endogenous growth framework, this paper empirically investigates the impact of financial capital on economic growth for a panel of 60 developing countries, through the channel of domestic capital formation. By estimating the model for different income groups, it is found that while private FDI flows exert beneficial complementarity effects on the domestic capital formation across all income-group countries, the official financial flows contribute to increasing investment in the middle income economies, but not in the low income countries. The latter appears to demonstrate that the aid-growth nexus is supported in the middle income countries, whereas the misallocation of official inflows is more likely to exist in the low income countries, suggesting that aid effectiveness remains conditional on the domestic policy environment

    An Engineered Methanogenic Pathway Derived from the Domains Bacteria and Archaea

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    A plasmid-based expression system wherein mekB was fused to a constitutive Methanosarcina acetivorans promoter was used to express MekB, a broad-specificity esterase from Pseudomonas veronii, in M. acetivorans. The engineered strain had 80-fold greater esterase activity than wild-type M. acetivorans. Methyl acetate and methyl propionate esters served as the sole carbon and energy sources, resulting in robust growth and methane formation, with consumption of >97% of the substrates. Methanol was undetectable at the end of growth with methyl acetate, whereas acetate accumulated, a result consistent with methanol as the more favorable substrate. Acetate was consumed, and growth continued after a period of adaptation. Similar results were obtained with methyl propionate, except propionate was not metabolized

    Observations of TeV gamma-rays from Mrk 421 during Dec. 2005 to Apr. 2006 with the TACTIC telescope

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    The TACTIC Îł\gamma-ray telescope has observed Mrk 421 on 66 clear nights from Dec. 07, 2005 to Apr. 30, 2006, totalling ∌\sim 202 hours of on-source observations. Here, we report the detection of flaring activity from the source at ≄\geq 1 TeV energy and the time-averaged differential Îł\gamma-ray spectrum in the energy range 1-11 TeV for the data taken between Dec. 27, 2005 to Feb. 07, 2006 when the source was in a relatively higher state as compared to the rest of the observation period. Analysis of this data spell, comprising about ∌\sim97h reveals the presence of a ∌12.0σ\sim 12.0 \sigma Îł\gamma-ray signal with daily flux of >> 1 Crab unit on several days. A pure power law spectrum with exponent −3.11±0.11-3.11\pm0.11 as well as a power law spectrum with an exponential cutoff (Γ=−2.51±0.26(\Gamma = -2.51\pm0.26 and E0=(4.7±2.1)TeV)E_0=(4.7\pm2.1) TeV) are found to provide reasonable fits to the inferred differential spectrum within statistical uncertainties. We believe that the TeV light curve presented here, for nearly 5 months of extensive coverage, as well as the spectral information at Îł\gamma-ray energies of >> 5 TeV provide a useful input for other groups working in the field of Îł\gamma-ray astronomy.Comment: 13pages,4figures; Accepted for publication in Astroparticle Physic

    Integrating high-throughput genetic interaction mapping and high-content screening to explore yeast spindle morphogenesis

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    A combination of yeast genetics, synthetic genetic array analysis, and high-throughput screening reveals that sumoylation of Mcm21p promotes disassembly of the mitotic spindle
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