538 research outputs found
Primordial black hole isocurvature modes from non-Gaussianity
Theoretical Physic
Occurrence, Fate, and Related Health Risks of PFAS in Raw and Produced Drinking Water
This study investigates
human exposure to per- and polyfluoroalkyl
substances (PFAS) via drinking water and evaluates human health risks.
An analytical method for 56 target PFAS, including ultrashort-chain
(C2–C3) and branched isomers, was developed. The limit of detection
(LOD) ranged from 0.009 to 0.1 ng/L, except for trifluoroacetic-acid
and perfluoropropanoic-acid with higher LODs of 35 and 0.24 ng/L,
respectively. The method was applied to raw and produced drinking
water from 18 Dutch locations, including groundwater or surface water
as source, and applied various treatment processes. Ultrashort-chain
(300 to 1100 ng/L) followed by the group of perfluoroalkyl-carboxylic-acids
(PFCA, ≥C4) (0.4 to 95.1 ng/L) were dominant. PFCA and perfluoroalkyl-sulfonic-acid
(≥C4), including precursors, showed significantly higher levels
in drinking water produced from surface water. However, no significant
difference was found for ultrashort PFAS, indicating the need for
groundwater protection. Negative removal of PFAS occasionally observed
for advanced treatment indicates desorption and/or degradation of
precursors. The proportion of branched isomers was higher in raw and
produced drinking water as compared to industrial production. Drinking
water produced from surface water, except for a few locations, exceed
non-binding provisional guideline values proposed; however, all produced
drinking waters met the recent soon-to-be binding drinking-water-directive
requirements
Examination of the role of Mycoplasma bovis in bovine pneumonia and a mathematical model for its evaluation
The authors screened 34 large cattle herds for the presence of Mycoplasma bovis infection by examining slaughtered cattle for macroscopic lung lesions, by culturing M. bovis from lung lesions and at the same time by testing sera for the presence of antibodies against M. bovis. Among the 595 cattle examined, 33.9% had pneumonic lesions, mycoplasmas were isolated from 59.9% of pneumonic lung samples, and 10.9% of sera from those animals contained antibodies to M.bovis. In 25.2% of the cases M. bovis was isolated from lungs with no macroscopic lesions. The proportion of seropositive herds was 64.7%. The average seropositivity rate of individuals was 11.3% but in certain herds it exceeded 50%. A probability model was developed for examining the relationship among the occurrence
of pneumonia, the isolation of M. bovis from the lungs and the presence of M. bovis specific antibodies in sera
Fast automatic quantitative cell replication with fluorescent live cell imaging
Hoffmann N, Keck M, Neuweger H, et al. Combining peak- and chromatogram-based retention time alignment algorithms for multiple chromatography-mass spectrometry datasets. BMC Bioinformatics. 2012;13(1): 21.Background
Modern analytical methods in biology and chemistry use separation techniques coupled to sensitive detectors, such as gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS). These hyphenated methods provide high-dimensional data. Comparing such data manually to find corresponding signals is a laborious task, as each experiment usually consists of thousands of individual scans, each containing hundreds or even thousands of distinct signals. In order to allow for successful identification of metabolites or proteins within such data, especially in the context of metabolomics and proteomics, an accurate alignment and matching of corresponding features between two or more experiments is required. Such a matching algorithm should capture fluctuations in the chromatographic system which lead to non-linear distortions on the time axis, as well as systematic changes in recorded intensities. Many different algorithms for the retention time alignment of GC-MS and LC-MS data have been proposed and published, but all of them focus either on aligning previously extracted peak features or on aligning and comparing the complete raw data containing all available features.
Results
In this paper we introduce two algorithms for retention time alignment of multiple GC-MS datasets: multiple alignment by bidirectional best hits peak assignment and cluster extension (BIPACE) and center-star multiple alignment by pairwise partitioned dynamic time warping (CEMAPP-DTW). We show how the similarity-based peak group matching method BIPACE may be used for multiple alignment calculation individually and how it can be used as a preprocessing step for the pairwise alignments performed by CEMAPP-DTW. We evaluate the algorithms individually and in combination on a previously published small GC-MS dataset studying the Leishmania parasite and on a larger GC-MS dataset studying grains of wheat (Triticum aestivum).
Conclusions
We have shown that BIPACE achieves very high precision and recall and a very low number of false positive peak assignments on both evaluation datasets. CEMAPP-DTW finds a high number of true positives when executed on its own, but achieves even better results when BIPACE is used to constrain its search space. The source code of both algorithms is included in the OpenSource software framework Maltcms, which is available from http://maltcms.sf.net webcite. The evaluation scripts of the present study are available from the same source
Interobserver variability between experienced and inexperienced observers in the histopathological analysis of Wilms tumors:a pilot study for future algorithmic approach
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