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- Aharonian, F., et al.
(författare)
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Simultaneous multiwavelength observations of the second exceptional gamma-ray flare of PKS2155-304 in July 2006
- 2009
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 502:3, s. 749-770
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Forskningsöversikt (refereegranskat)abstract
- Aims. The X-ray-TeV connection and the evolution of the emitting particle population is studied in high-energy peaked BL Lac objects, by obtaining spectral information in both bands on sub-hour timescales. Methods. Simultaneous observations with HESS, Chandra and the Bronberg optical observatory were performed on the BL Lac object PKS 2155-304 in the night of July 29-30 2006, when the source underwent a major gamma-ray outburst during its high-activity state of Summer 2006. This event took place about 44 h after the other major outburst of the night of July 27-28, which is known for its ultrafast variability. An unprecedented 6 to 8 h of simultaneous, uninterrupted coverage was achieved, with spectra and light curves measured down to 7 and 2 min timescales, respectively. Results. The source exhibited one major flare along the night, at high energies. The gamma-ray flux reached a maximum of similar to 11 times the Crab flux (>400 GeV), with rise/decay timescales of similar to 1 h, plus a few smaller-amplitude flares superimposed on the decaying phase. The emission in the X-ray and VHE gamma-ray bands is strongly correlated, with no evidence of lags. The spectra also evolve with similar patterns, and are always soft ( photon index G > 2), indicating no strong shift of the peaks in the spectral energy distribution towards higher energies. Only at the flare maximum is there evidence that the gamma-ray peak is inside the observed passband, at similar to 400-600 GeV. The VHE spectrum shows a curvature that is variable with time and stronger at higher fluxes. The huge VHE variations (similar to 22x) are only accompanied by small-amplitude X-ray and optical variations (factor 2 and 15% respectively). The source has shown for the first time in a high-energy peaked BL Lac object a large Compton dominance (L(C)/L(S) similar to 10) - rapidly evolving - and a cubic relation between VHE and X-ray flux variations, during a decaying phase. These results challenge the common scenarios for the TeV-blazar emission.
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- Sever, Mehmet Sukru, et al.
(författare)
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A roadmap for optimizing chronic kidney disease patient care and patient-oriented research in the Eastern European nephrology community
- 2021
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Ingår i: Clinical Kidney Journal. - : Oxford University Press. - 2048-8505 .- 2048-8513. ; 14:1, s. 23-35
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Forskningsöversikt (refereegranskat)abstract
- Chronic kidney disease (CKD) is a major health problem because of its high prevalence, associated complications and high treatment costs. Several aspects of CKD differ significantly in the Eastern European nephrology community compared with Western Europe because of different geographic, socio-economic, infrastructure, cultural and educational features. The two most frequent aetiologies of CKD, DM and hypertension, and many other predisposing factors, are more frequent in the Eastern region, resulting in more prevalent CKD Stages 3-5. Interventions may minimize the potential drawbacks of the high prevalence of CKD in Eastern Europe, which include several options at various stages of the disease, such as raising public, medical personnel and healthcare authorities awareness; early detection by screening high-risk populations; preventing progression and CKD-related complications by training health professionals and patients; promoting transplantation or home dialysis as the preferred modality; disseminating and implementing guidelines and guided therapy and encouraging/supporting country-specific observational research as well as international collaborative projects. Specific ways to significantly impact CKD-related problems in every region of Europe through education, science and networking are collaboration with non-nephrology European societies who have a common interest in CKD and its associated complications, representation through an advisory role within nephrology via national nephrology societies, contributing to the training of local nephrologists and stimulating patient-oriented research. The latter is mandatory to identify country-specific kidney disease-related priorities. Active involvement of patients in this research via collaboration with the European Kidney Patient Federation or national patient federations is imperative to ensure that projects reflect specific patient needs.
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- Wilson, Stephen A., et al.
(författare)
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New materials for micro-scale sensors and actuators An engineering review
- 2007
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Ingår i: Materials science & engineering. R, Reports. - : Elsevier BV. - 0927-796X .- 1879-212X. ; 56:06-jan, s. 1-129
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Forskningsöversikt (refereegranskat)abstract
- This paper provides a detailed overview of developments in transducer materials technology relating to their current and future applications in micro-scale devices. Recent advances in piezoelectric, magnetostrictive and shape-memory alloy systems are discussed and emerging transducer materials such as magnetic nanoparticles, expandable micro-spheres and conductive polymers are introduced. Materials properties, transducer mechanisms and end applications are described and the potential for integration of the materials with ancillary systems components is viewed as an essential consideration. The review concludes with a short discussion of structural polymers that are extending the range of micro-fabrication techniques available to designers and production engineers beyond the limitations of silicon fabrication technology.
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- Delanaye, Pierre, et al.
(författare)
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CKD : A Call for an Age-Adapted Definition
- 2019
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Ingår i: Journal of the American Society of Nephrology. - 1046-6673. ; 30:10, s. 1785-1805
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Forskningsöversikt (refereegranskat)abstract
- Current criteria for the diagnosis of CKD in adults include persistent signs of kidney damage, such as increased urine albumin-to-creatinine ratio or a GFR below the threshold of 60 ml/min per 1.73 m2 This threshold has important caveats because it does not separate kidney disease from kidney aging, and therefore does not hold for all ages. In an extensive review of the literature, we found that GFR declines with healthy aging without any overt signs of compensation (such as elevated single-nephron GFR) or kidney damage. Older living kidney donors, who are carefully selected based on good health, have a lower predonation GFR compared with younger donors. Furthermore, the results from the large meta-analyses conducted by the CKD Prognosis Consortium and from numerous other studies indicate that the GFR threshold above which the risk of mortality is increased is not consistent across all ages. Among younger persons, mortality is increased at GFR <75 ml/min per 1.73 m2, whereas in elderly people it is increased at levels <45 ml/min per 1.73 m2 Therefore, we suggest that amending the CKD definition to include age-specific thresholds for GFR. The implications of an updated definition are far reaching. Having fewer healthy elderly individuals diagnosed with CKD could help reduce inappropriate care and its associated adverse effects. Global prevalence estimates for CKD would be substantially reduced. Also, using an age-specific threshold for younger persons might lead to earlier identification of CKD onset for such individuals, at a point when progressive kidney damage may still be preventable.
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