1,543 research outputs found
Saturn's aurora observed by the Cassini camera at visible wavelengths
The first observations of Saturn's visible-wavelength aurora were made by the
Cassini camera. The aurora was observed between 2006 and 2013 in the northern
and southern hemispheres. The color of the aurora changes from pink at a few
hundred km above the horizon to purple at 1000-1500 km above the horizon. The
spectrum observed in 9 filters spanning wavelengths from 250 nm to 1000 nm has
a prominent H-alpha line and roughly agrees with laboratory simulated auroras.
Auroras in both hemispheres vary dramatically with longitude. Auroras form
bright arcs between 70 and 80 degree latitude north and between 65 and 80
degree latitude south, which sometimes spiral around the pole, and sometimes
form double arcs. A large 10,000-km-scale longitudinal brightness structure
persists for more than 100 hours. This structure rotates approximately together
with Saturn. On top of the large steady structure, the auroras brighten
suddenly on the timescales of a few minutes. These brightenings repeat with a
period of about 1 hour. Smaller, 1000-km-scale structures may move faster or
lag behind Saturn's rotation on timescales of tens of minutes. The persistence
of nearly-corotating large bright longitudinal structure in the auroral oval
seen in two movies spanning 8 and 11 rotations gives an estimate on the period
of 10.65 0.15 h for 2009 in the northern oval and 10.8 0.1 h for 2012
in the southern oval. The 2009 north aurora period is close to the north branch
of Saturn Kilometric Radiation (SKR) detected at that time.Comment: 39 pages, 8 figures, 1 table, 6 supplementary movies, accepted to
Icaru
Application of amplitude thresholding to aid minimum energy adaptive subtraction for multiple attenuation
Model based multiple prediction approaches require an adaptive subtraction step that is able to correct for differences between the real and predicted multiples. The commonly used subtraction process derives shaping operators, in the least squares sense, to minimize the energy difference between the predicted multiples and the field record. Although the minimum energy assumption allows a computationally efficient adaptive subtraction, it can lead to attenuation of primary information. This abstract illustrates how a simple amplitude clipping approach can significantly improve the effectiveness of the least squares adaptive subtraction and minimize primary attenuation
Prevalence of sulfonamide resistance genes in bacterial isolates from manured agricultural soils and pig slurry in the United Kingdom
Prevalence of three sulfonamide resistance genes, sul1, sul2 and sul3 and sulfachloropyridazine (SCP) resistance was determined in bacteria isolated from UK manured agricultural clay soils and slurry samples, over a two year period. Slurry from tylosin-fed pigs amended with SCP and oxytetracycline (OTC) was used for manuring. Sul gene positive isolates were further screened for the presence of class 1 and 2 integrons. Phenotypic resistance to SCP was significantly higher in pig slurry and post application soil than in pre-application soil. Of 5isolates, 23 % carried sul1, 18 % sul2 and 9 % sul3 only. Two percent of isolates contained all three sul genes. Class 1 and class 2 integrons were identified in 5 % and 11.7 % of sul positive isolates. In previous reports, sul1 was linked to class 1 integrons, but in this study only 8 % of sul1 positive isolates carried the intI1 gene. Sulfonamide resistant pathogens were identified in slurry amended soil and soil leachate, including Shigella flexneri, Aerococcus spp. and Acinetobacter baumanni, suggesting a potential environmental reservoir. Sulfonamide resistance in Psychrobacter, Enterococcus and Bacillus spp. is reported for the first time, and this study also provides the first description of the genotype sul1, sul2 and sul3 outside the Enterobacteriacae, and in the soil environment
Microbial imbalance in inflammatory bowel disease patients at different taxonomic levels
Background
Inflammatory bowel disease (IBD), is a debilitating group of chronic diseases including Crohnās Disease (CD) and ulcerative colitis (UC), which causes inflammation of the gut and affects millions of people worldwide. At different taxonomic levels, the structure of the gut microbiota is significantly altered in IBD patients compared to that of healthy individuals. However, it is unclear how these IBD-affected bacterial groups are related to other common bacteria in the gut, and how they are connected across different disease conditions at the global scale.
Results
In this study, using faecal samples from patients with IBD, we show through diversity analysis of the microbial community structure based on the 16S rRNA gene that the gut microbiome of IBD patients is less diverse compared to healthy individuals. Furthermore, we have identified which bacterial groups change in abundance in both CD and UC compared to healthy controls. A substantial imbalance was observed across four major bacterial phyla including Firmicutes, Bacteroidetes, Proteobacteria and Actinobacteria, which together constitute >98% of the gut microbiota. Next, we reconstructed a bacterial family co-abundance network based on the correlation of abundance profiles obtained from the public gut microbiome data of >22000 samples of faecal and gut biopsies taken from both diseased and healthy individuals. The data was compiled using the EBI metagenomics database [1]. By mapping IBD-altered bacterial families to the network, we show that the bacterial families which exhibit an increased abundance in IBD conditions are not well connected to other groups, implying that these families generally do not coexist together with common gut organisms. Whereas, the bacterial families whose abundance is reduced or did not change in IBD conditions compared to healthy conditions are very well connected to other bacterial groups, suggesting they are highly important groups of bacteria in the gut that can coexist with other bacteria across a range of conditions.
Conclusions
IBD patients exhibited a less diverse gut microbiome compared to healthy individuals. Bacterial groups which changed in IBD patients were found to be groups which do not co-exist well with common commensal gut bacteria, whereas bacterial groups which did not change in patients with IBD were found to commonly co-exist with commensal gut microbiota. This gives a potential insight into the dynamics of the gut microbiota in patients with IBD
Should environmental effects be included when performing QTAIM calculations on actinide systems?:a comparison of QTAIM metrics for Cs2UO2Cl4, U(Se2PPh2)4 and Np(Se2PPh2)4 in gas phase, COSMO and PEECM
Quantum Theory of AtomsāināMolecules bond critical point and delocalisation index metrics are calculated for the actinide-element bonds in Cs2UO2Cl4, U(Se2PPh2)4 and Np(Se2PPh2)4, in gas-phase, continuum solvent (COSMO) and via the periodic electrostatic embedded cluster method. The effects of the environment are seen to be very minor, suggesting that they do not account for the differences previously observed between the experimental and theoretical QTAIM Ļb and ā2Ļb for the U-O bonds in Cs2UO2Cl4. With the exception of the local density approximation, there is only a small dependence of the QTAIM metrics on the exchangeācorrelation functional employed
Endometrial injury in women undergoing assisted reproductive techniques
ACKNOWLEDGEMENTS We would like to express our appreciation to Dra Abha Maheshwari for her important authorial contribution to the previous version of this review. We also acknowledge the important help provided by the Cochrane Menstrual Disorders and Subfertility Group team, specially by Marian Showell, Trials Search Co-ordinator; by Helen Nagels, Managing Editor; and by Prof. Cindy Farquhar, Co-ordinating Editor. Finally, we would like to express our gratitude to the following investigators, who provided essential information for the preparation of this review: TK Aleyamma, Erin F Wolff, Lukasz Polanski, Nava Dekel, Neeta Singh, Suleyman Guven and Tracy YeungPeer reviewedPublisher PD
Environmental monitoring of Mycobacterium bovis in badger feces and badger sett soil by real-time PCR, as confirmed by immunofluorescence, immunocapture, and cultivation
Real-time PCR was used to detect and quantify Mycobacterium bovis cells in
naturally infected soil and badger faeces. Immunomagnetic capture,
immunofluorescence and selective culture confirmed species identification and cell
viability. These techniques will prove useful for monitoring M. bovis in the
environment and for elucidating transmission routes between wildlife and cattle
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