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- Backis, A., et al.
(författare)
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Time- and energy-resolved effects in the boron-10 based multi-grid and helium-3 based thermal neutron detectors
- 2021
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Ingår i: Measurement science and technology. - : IOP PUBLISHING LTD. - 0957-0233 .- 1361-6501. ; 32:3
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Tidskriftsartikel (refereegranskat)abstract
- The boron-10 based multi-grid detector is being developed as an alternative to helium-3 based neutron detectors. At the European Spallation Source, the detector will be used for time-of-flight neutron spectroscopy at cold to thermal neutron energies. The objective of this work is to investigate fine time- and energy-resolved effects of the Multi-Grid detector, down to a few mu eV, while comparing it to the performance of a typical helium-3 tube. Furthermore, it is to characterize differences between the detector technologies in terms of internal scattering, as well as the time reconstruction of similar to mu s short neutron pulses. The data were taken at the Helmholtz Zentrum Berlin, where the Multi-Grid detector and a helium-3 tube were installed at the ESS test beamline, V20. Using a Fermi-chopper, the neutron beam of the reactor was chopped into a few tens of mu s wide pulses before reaching the detector, located a few tens of cm downstream. The data of the measurements show an agreement between the derived and calculated neutron detection efficiency curve. The data also provide fine details on the effect of internal scattering, and how it can be reduced. For the first time, the chopper resolution was comparable to the timing resolution of the Multi-Grid detector. This allowed a detailed study of time- and energy resolved effects, as well as a comparison with a typical helium-3 tube.
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| 4. |
- Flesch, BK, et al.
(författare)
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Multicenter Study on Differential Human Neutrophil Antigen 2 Expression and Underlying Molecular Mechanisms
- 2020
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Ingår i: Transfusion medicine and hemotherapy : offizielles Organ der Deutschen Gesellschaft fur Transfusionsmedizin und Immunhamatologie. - : S. Karger AG. - 1660-3796. ; 47:5, s. 385-395
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Tidskriftsartikel (refereegranskat)abstract
- <b><i>Background:</i></b> The human neutrophil antigen 2 (HNA-2), which is expressed on CD177, is undetectable in 3–5% of the normal population. Exposure of these HNA-2<sub>null</sub> individuals to HNA-2-positive cells can cause immunization and production of HNA-2 antibodies, which can induce immune neutropenia and transfusion-related acute lung injury. In HNA-2-positive individuals, neutrophils are divided into a CD177<sup>pos.</sup> and a CD177<sup>neg.</sup> subpopulation. The molecular background of HNA-2 deficiency and the bimodal expression pattern, however, are not completely decoded. <b><i>Study Design:</i></b> An international collaboration was conducted on the genetic analysis of HNA-2-phenotyped blood samples, including HNA-2-deficient individuals, mothers, and the respective children with neonatal immune neutropenia and regular blood donors. <b><i>Results:</i></b> From a total of 54 HNA-2<sub>null</sub> individuals, 43 were homozygous for the <i>CD177</i>*<i>787A>T</i> substitution. Six carried the <i>CD177</i>*<i>c.1291G>A</i> single nucleotide polymorphism. All HNA-2-positive samples with >40% CD177<sup>pos.</sup> neutrophils carried the *<i>787A</i> wild-type allele, whereas a lower rate of CD177<sup>pos.</sup> neutrophils was preferentially associated with *<i>c.787AT</i> heterozygosity. Interestingly, only the *<i>c.787A</i> allele sequence was detected in complementary DNA (cDNA) sequence analysis carried out on all *<i>c.787AT</i> heterozygous individuals. However, cDNA analysis after sorting of CD177<sup>pos.</sup> and CD177<sup>neg.</sup> neutrophil subsets from HNA-2-positive individuals showed identical sequences, which makes regulatory elements within the promoter unlikely to affect <i>CD177</i> gene transcription in different CD177 neutrophil subsets. <b><i>Conclusion:</i></b> This comprehensive study clearly demonstrates the impact of single nucleotide polymorphisms on the expression of HNA-2 on the neutrophil surface but challenges the hypothesis of regulatory epigenetic effects being implicated in the bimodal CD177 expression pattern.
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| 5. |
- Luu, TT, et al.
(författare)
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Short-term IL-15 priming leaves a long-lasting signalling imprint in mouse NK cells independently of a metabolic switch
- 2021
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Ingår i: Life science alliance. - : Life Science Alliance, LLC. - 2575-1077. ; 4:4
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Tidskriftsartikel (refereegranskat)abstract
- IL-15 priming of NK cells is a broadly accepted concept, but the dynamics and underlying molecular mechanisms remain poorly understood. We show that as little as 5 min of IL-15 treatment in vitro, followed by removal of excess cytokines, results in a long-lasting, but reversible, augmentation of NK cell responsiveness upon activating receptor cross-linking. In contrast to long-term stimulation, improved NK cell function after short-term IL-15 priming was not associated with enhanced metabolism but was based on the increased steady-state phosphorylation level of signalling molecules downstream of activating receptors. Inhibition of JAK3 eliminated this priming effect, suggesting a cross talk between the IL-15 receptor and ITAM-dependent activating receptors. Increased signalling molecule phosphorylation levels, calcium flux, and IFN-γ secretion lasted for up to 3 h after IL-15 stimulation before returning to baseline. We conclude that IL-15 rapidly and reversibly primes NK cell function by modulating activating receptor signalling. Our findings suggest a mechanism by which NK cell reactivity can potentially be maintained in vivo based on only brief encounters with IL-15 trans-presenting cells.
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| 7. |
- Muraro, A., et al.
(författare)
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MBGEM : a stack of borated GEM detector for high efficiency thermal neutron detection
- 2021
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Ingår i: The European Physical Journal Plus. - : SPRINGER HEIDELBERG. - 2190-5444. ; 136:7
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Tidskriftsartikel (refereegranskat)abstract
- A new position-sensitive thermal neutron detector based on boron-coated converters has been developed as an alternative to todays standard -based technology for application to thermal neutron scattering. The key elements of the development are the boron-coated GEM foils (Sauli in Nucl Instrum Methods Phys Res Sect A Accel Spectrom Detect Assoc Equip 386:531, 1997) that are used as a multi-layer neutron converter via the reaction together with an efficient collection of the produced secondary electrons. This paper reports the test performed on a 3 layers converter prototype coupled to a GEMPix detector (Murtas in Radiat Meas 138:106421, 2020), carried out in order to study the possibility to produce a large-scale multi-layer neutron detector capable to reach high detection efficiency with high spatial resolution and able to sustain the high neutron flux expected in the new neutron spallation source under development like the ESS.
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| 8. |
- Ramos Santesmases, David, et al.
(författare)
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Quasi-3-dimensional simulations and experimental validation of surface leakage currents in high operating temperature type-II superlattice infrared detectors
- 2022
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 132:20, s. 204501-
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Tidskriftsartikel (refereegranskat)abstract
- The surface leakage in InAs/GaSb type-II superlattice (T2SL) is studied experimentally and theoretically for photodiodes with small sizes down to 10 x 10 mu m(2). The dependence of dark current density on mesa size is studied at 110 and 200 K, and surface leakage is shown to impact both generation-recombination (GR) and diffusion dark current mechanisms. A quasi-3-dimensional model to simulate the fabrication process using surface traps on the pixel's sidewall is presented and is used to accurately represent the dark current of large and small pixels with surface leakage in the different temperature regimes. The simulations confirmed that the surface leakage current has a GR and diffusion component at low and high temperature, respectively. Finally, the surface leakage current has been correlated with the change in minority carrier concentration at the surface due to the presence of donor traps.
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