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- Jonsson, Per R., 1957, et al.
(författare)
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Making water flow: a comparison of the hydrodynamic characteristics of 12 different benthic biological flumes
- 2006
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Ingår i: Aquatic Ecology. - : Springer Science and Business Media LLC. - 1386-2588 .- 1573-5125. ; 40:4, s. 409-438
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Tidskriftsartikel (refereegranskat)abstract
- Flume tanks are becoming increasingly important research tools in aquatic ecology, to link biological to hydrodynamical processes. There is no such thing as a "standard flume tank", and no flume tank is suitable for every type of research question. A series of experiments has been carried out to characterise and compare the hydrodynamic characteristics of 12 different flume tanks that are designed specifically for biological research. These facilities are part of the EU network BioFlow. The flumes could be divided into four basic design types: straight, racetrack, annular and field flumes. In each facility, two vertical velocity profiles were measured: one at 0.05 m s(-1) and one at 0.25 m s(-1). In those flumes equipped with Acoustic Doppler Velocimeters (ADV), time series were also recorded for each velocity at two heights above the bottom: 0.05 m and 20% of the water depth. From these measurements turbulence characteristics, such as TKE and Reynolds stress, were derived, and autocorrelation spectra of the horizontal along-stream velocity component were plotted. The flume measurements were compared to two sets of velocity profiles measured in the field. Despite the fact that some flumes were relatively small, turbulence was fully developed in all channels. Straight and racetrack flumes generally produced boundary layers with a clearly definable logarithmic layer, similar to measurements in the field taken under steady flow conditions. The two annular flumes produced relatively thin boundary layers, presumably due to secondary flows developing in the curved channels. The profiles in the field flumes also differed considerably from the expected log profile. This may either have been due the construction of the flume, or due to unsteady conditions during measurement. Constraints imposed by the different flume designs on the suitability for different types of boundary layer research, as well as scaling issues are discussed.
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| 2. |
- Precht, H., et al.
(författare)
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Comparison of image quality in chest, hip and pelvis examinations between mobile equipment in nursing homes and static indirect radiography equipment in the hospital
- 2020
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Ingår i: Radiography. - : Elsevier BV. - 1078-8174. ; 26:2, s. 31-37
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: A hospital environment can be a significant burden and a health risk especially for dementia patients. Mobile x-ray equipment (ME) is used to enable imaging of these patients at home. The aim was to compare image quality (IQ) of chest, hip and pelvis images from ME to the stationary equipment (SE) used in a hospital department. Methods: We analysed examinations of the chest (n = 20), hip (n = 64) and pelvis (n = 32). Images were equally obtained from each setting of ME and SE. All images were graded using Visual Grading Analysis (VGA) by three radiographers (hip and pelvis) and three radiologists (chest). Technical IQ assessment was done by 80 additional images of a Contrast-Detail Radiography phantom (CDRAD). Results: All chest images were approved for diagnostic use, as well as the hip AP and pelvis images from SE. ‘Approved proportion of ME images was for HIP antero-posterior (AP) and pelvis, 78% [95% CI: 52–94%] and 81% [95% CI: 54–96%] respectively. Hip axial had an overall low, but not significant different approval rate. Ordered logistic regression indicated higher IQ of HIP AP and pelvic images from SE. This contrasts that the CDRAD substudy indicated better IQ, expressed as IQFinv, from ME. Conclusion: The VGA showed higher IQ for the SE system, while the CDRAD showed higher IQ for the ME system. Implications for practice: Dementia patients can be examined at their home if the acquisition is optimised according to image quality in conjunct to radiation dose. Performing imaging out of the hospital and coordinating the patients’ further treatment are new work areas for radiographers and requires excellent communication skills.
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| 3. |
- Schröder, Björn, et al.
(författare)
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Paneth cell α-defensin 6 (HD-6) is an antimicrobial peptide
- 2015
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Ingår i: Mucosal Immunology. - : Nature Publishing Group. - 1933-0219 .- 1935-3456. ; 8:3, s. 661-671
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Tidskriftsartikel (refereegranskat)abstract
- Defensins protect human barriers from commensal and pathogenic microorganisms. Human α-defensin 6 (HD-6) is produced exclusively by small intestinal Paneth cells but, in contrast to other antimicrobial peptides (AMPs) for HD-6, no direct antibacterial killing activity has been detected so far. Herein, we systematically tested how environmental factors, like pH and reducing conditions, affect antimicrobial activity of different defensins against anaerobic bacteria of the human intestinal microbiota. Remarkably, by mimicking the intestinal milieu we detected for the first time antibacterial activity of HD-6. Activity was observed against anaerobic gut commensals but not against some pathogenic strains. Antibiotic activity was attributable to the reduced peptide and independent of free cysteines or a conserved histidine residue. Furthermore, the oxidoreductase thioredoxin, which is also expressed in Paneth cells, is able to reduce a truncated physiological variant of HD-6. Ultrastructural analyses revealed that reduced HD-6 causes disintegration of cytoplasmic structures and alterations in the bacterial cell envelope, while maintaining extracellular net-like structures. We conclude that HD-6 is an antimicrobial peptide. Our data suggest two distinct antimicrobial mechanisms by one peptide: HD-6 kills specific microbes depending on the local environmental conditions, whereas known microbial trapping by extracellular net structures is independent of the reducing milieu.
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