1,936 research outputs found
Editorial: Controversies and solutions in environmental sciences: Addressing toxicity of sediments and soils
This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2007 Ecomed Publishers
Dynamics of the hydrocarbon-degrading Cycloclasticus bacteria during mesocosm-simulated oil spills
Original research articleWe used catalysed reported deposition – fluorescence in situ hybridization (CARD-FISH) to analyse changes in the abundance of the bacterial groups Alphaproteobacteria, Gammaproteobacteria and Bacteroidetes, and of hydrocarbon-degrading Cycloclasticus bacteria in mesocosms that had received polycyclic aromatic hydrocarbons (PAHs) additions. The effects of PAHs were assessed under four contrasting hydrographic conditions in the coastal upwelling system of the RÃas Baixas: winter mixing, spring bloom, summer stratification and autumn upwelling. We used realistic additions of water soluble PAHs (approximately 20–30 μg l−1 equivalent of chrysene), but during the winter period we also investigated the effect of higher PAHs concentrations (10–80 μg l−1 chrysene) on the bacterial community using microcosms. The most significant change observed was a significant reduction (68 ± 5%) in the relative abundance of Alphaproteobacteria. The magnitude of the response of Cycloclasticus bacteria (positive with probe CYPU829) to PAHs additions varied depending on the initial environmental conditions, and on the initial concentration of added PAHs. Our results clearly show that bacteria of the Cycloclasticus group play a major role in low molecular weight PAHs biodegradation in this planktonic ecosystem. Their response was stronger in colder waters, when their background abundance was also higher. During the warm periods, the response of Cycloclasticus was limited, possibly due to both, a lower bioavailability of PAHs caused by abiotic factors (solar radiation, temperature), and by inorganic nutrient limitation of bacterial growth.This research was supported by the MEC contract IMPRESION (VEM2003-20021); an European Community Marie Curie Reintegration Fellowship (MERG-CT-2004-511937) and a Juan de la Cierva-MEC contract.Versión del editor5,84
Casting Alloys: the Materials and "the Clinical Effects"
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67282/2/10.1177_08959374920060011101.pd
Stochastic optimization of a cold atom experiment using a genetic algorithm
We employ an evolutionary algorithm to automatically optimize different
stages of a cold atom experiment without human intervention. This approach
closes the loop between computer based experimental control systems and
automatic real time analysis and can be applied to a wide range of experimental
situations. The genetic algorithm quickly and reliably converges to the most
performing parameter set independent of the starting population. Especially in
many-dimensional or connected parameter spaces the automatic optimization
outperforms a manual search.Comment: 4 pages, 3 figure
Single-particle-sensitive imaging of freely propagating ultracold atoms
We present a novel imaging system for ultracold quantum gases in expansion.
After release from a confining potential, atoms fall through a sheet of
resonant excitation laser light and the emitted fluorescence photons are imaged
onto an amplified CCD camera using a high numerical aperture optical system.
The imaging system reaches an extraordinary dynamic range, not attainable with
conventional absorption imaging. We demonstrate single-atom detection for
dilute atomic clouds with high efficiency where at the same time dense
Bose-Einstein condensates can be imaged without saturation or distortion. The
spatial resolution can reach the sampling limit as given by the 8 \mu m pixel
size in object space. Pulsed operation of the detector allows for slice images,
a first step toward a 3D tomography of the measured object. The scheme can
easily be implemented for any atomic species and all optical components are
situated outside the vacuum system. As a first application we perform
thermometry on rubidium Bose-Einstein condensates created on an atom chip.Comment: 24 pages, 10 figures. v2: as publishe
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