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- Pennicard, David, et al.
(författare)
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LAMBDA 2M GaAs - A multi-megapixel hard X-ray detector for synchrotrons
- 2018
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Ingår i: Journal of Instrumentation. - 1748-0221 .- 1748-0221. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Synchrotrons can provide very intense and focused X-ray beams, which can be used to study the structure of matter down to the atomic scale. In many experiments, the quality of the results depends strongly on detector performance; in particular, experiments studying dynamics of samples require fast, sensitive X-ray detectors. "LAMBDA" is a photon-counting hybrid pixel detector system for experiments at synchrotrons, based on the Medipix3 readout chip. Its main features are a combination of comparatively small pixel size (55 μm), high readout speed at up to 2000 frames per second with no time gap between images, a large tileable module design, and compatibility with high-Z sensors for efficient detection of higher X-ray energies. A large LAMBDA system for hard X-ray detection has been built using Cr-compensated GaAs as a sensor material. The system is composed of 6 GaAs tiles, each of 768 by 512 pixels, giving a system with approximately 2 megapixels and an area of 8.5 by 8.5 cm2. While the sensor uniformity of GaAs is not as high as that of silicon, its behaviour is stable over time, and it is possible to correct nonuniformities effectively by postprocessing of images. By using multiple 10 Gigabit Ethernet data links, the system can be read out at the full speed of 2000 frames per second. The system has been used in hard X-ray diffraction experiments studying the structure of samples under extreme pressure in diamond anvil cells. These experiments can provide insight into geological processes. Thanks to the combination of high speed readout, large area and high sensitivity to hard X-rays, it is possible to obtain previously unattainable information in these experiments about atomic-scale structure on a millisecond timescale during rapid changes of pressure or temperature.
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| 2. |
- Sarajlic, P, et al.
(författare)
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Enhanced ventricular-arterial coupling during a 2-year physical activity programme in patients with rheumatoid arthritis : a prospective substudy of the physical activity in rheumatoid arthritis 2010 trial.
- 2018
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Ingår i: Journal of Internal Medicine. - : Wiley. - 0954-6820 .- 1365-2796. ; 284:6, s. 664-673
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To establish how guided physical activity in patients with rheumatoid arthritis (RA) without known cardiovascular disease affected vascular and cardiac function, and how these two entities were prospectively interconnected in this patient group.METHODS: Prospective substudy of 29 participants in the Physical Activity in RA (PARA) 2010 trial. All subjects were examined at baseline, at year 1 and 2 with measures of pulse wave velocity and arterial augmentation index, as well as echocardiographic evaluation of diastolic parameters and ventricular-arterial coupling. Muscle strength and aerobic exercise capacity were assessed at baseline and yearly. All participants performed physiotherapist-guided aerobic and muscle strength exercise during 2 years and were reminded through SMS to report physical activity progress.RESULTS: This cohort of patients with RA exhibited increased vascular stiffness despite normal blood pressure. At baseline, lower muscle strength was associated with increased vascular stiffness (β = 0.68; P = 0.004), whereas lower aerobic working capacity was associated with left ventricular diastolic dysfunction (β = 0.85; P = 0.03). There was a significant positive correlation between vascular stiffness and diastolic dysfunction at baseline (R2 = 0.64) and for the changes in those parameters observed during 2 years of guided physical activity. Finally, a significant improvement in ventricular-arterial coupling was observed after exercise (P < 0.001).CONCLUSION: These results indicate that although differentially associated with physical capacity parameters, improved vascular stiffness and improved diastolic dysfunction are interrelated, and that an optimization of the ventricular-arterial coupling may contribute to the beneficial effects of physical activity in patients with RA.
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