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- Korablev, O., et al.
(författare)
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The Atmospheric Chemistry Suite (ACS) of Three Spectrometers for the ExoMars 2016 Trace Gas Orbiter
- 2018
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Ingår i: Space Science Reviews. - : Springer. - 0038-6308 .- 1572-9672. ; 214:1
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Tidskriftsartikel (refereegranskat)abstract
- The Atmospheric Chemistry Suite (ACS) package is an element of the Russian contribution to the ESA-Roscosmos ExoMars 2016 Trace Gas Orbiter (TGO) mission. ACS consists of three separate infrared spectrometers, sharing common mechanical, electrical, and thermal interfaces. This ensemble of spectrometers has been designed and developed in response to the Trace Gas Orbiter mission objectives that specifically address the requirement of high sensitivity instruments to enable the unambiguous detection of trace gases of potential geophysical or biological interest. For this reason, ACS embarks a set of instruments achieving simultaneously very high accuracy (ppt level), very high resolving power (>10,000) and large spectral coverage (0.7 to 17 μm—the visible to thermal infrared range). The near-infrared (NIR) channel is a versatile spectrometer covering the 0.7–1.6 μm spectral range with a resolving power of ∼20,000. NIR employs the combination of an echelle grating with an AOTF (Acousto-Optical Tunable Filter) as diffraction order selector. This channel will be mainly operated in solar occultation and nadir, and can also perform limb observations. The scientific goals of NIR are the measurements of water vapor, aerosols, and dayside or night side airglows. The mid-infrared (MIR) channel is a cross-dispersion echelle instrument dedicated to solar occultation measurements in the 2.2–4.4 μm range. MIR achieves a resolving power of >50,000. It has been designed to accomplish the most sensitive measurements ever of the trace gases present in the Martian atmosphere. The thermal-infrared channel (TIRVIM) is a 2-inch double pendulum Fourier-transform spectrometer encompassing the spectral range of 1.7–17 μm with apodized resolution varying from 0.2 to 1.3 cm−1. TIRVIM is primarily dedicated to profiling temperature from the surface up to ∼60 km and to monitor aerosol abundance in nadir. TIRVIM also has a limb and solar occultation capability. The technical concept of the instrument, its accommodation on the spacecraft, the optical designs as well as some of the calibrations, and the expected performances for its three channels are described.
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| 3. |
- Nelson, A. J., et al.
(författare)
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Soft x-ray free electron laser microfocus for exploring matter under extreme conditions
- 2009
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Ingår i: Optics Express. - 1094-4087. ; 17:20, s. 18271-18278
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Tidskriftsartikel (refereegranskat)abstract
- We have focused a beam (BL3) of FLASH (Free-electron LASer in Hamburg: lambda = 13.5 nm, pulse length 15 fs, pulse energy 10-40 mu J, 5Hz) using a fine polished off-axis parabola having a focal length of 270 mm and coated with a Mo/Si multilayer with an initial reflectivity of 67% at 13.5 nm. The OAP was mounted and aligned with a picomotor controlled six-axis gimbal. Beam imprints on poly(methyl methacrylate) -PMMA were used to measure focus and the focused beam was used to create isochoric heating of various slab targets. Results show the focal spot has a diameter of <= 1 mu m. Observations were correlated with simulations of best focus to provide further relevant information.
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| 6. |
- Grouwels, G., et al.
(författare)
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Differentiating neural crest stem cells induce proliferation of cultured rodent islet beta cells
- 2012
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 0012-186X .- 1432-0428. ; 55:7, s. 2016-2025
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Tidskriftsartikel (refereegranskat)abstract
- Aims/hypothesisEfficient stimulation of cycling activity in cultured beta cells would allow the design of new strategies for cell therapy in diabetes. Neural crest stem cells (NCSCs) play a role in beta cell development and maturation and increase the beta cell number in co-transplants. The mechanism behind NCSC-induced beta cell proliferation and the functional capacity of the new beta cells is not known.MethodsWe developed a new in vitro co-culture system that enables the dissection of the elements that control the cellular interactions that lead to NCSC-dependent increase in islet beta cells.ResultsMouse NCSCs were cultured in vitro, first in medium that stimulated their proliferation, then under conditions that supported their differentiation. When mouse islet cells were cultured together with the NCSCs, more than 35% of the beta cells showed cycle activity. This labelling index is more than tenfold higher than control islets cultured without NCSCs. Beta cells that proliferated under these culture conditions were fully glucose responsive in terms of insulin secretion. NCSCs also induced beta cell proliferation in islets isolated from 1-year-old mice, but not in dissociated islet cells isolated from human donor pancreas tissue. To stimulate beta cell proliferation, NCSCs need to be in intimate contact with the beta cells.Conclusions/interpretationCulture of islet cells in contact with NCSCs induces highly efficient beta cell proliferation. The reported culture system is an excellent platform for further dissection of the minimal set of factors needed to drive this process and explore its potential for translation to diabetes therapy.
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| 7. |
- Hanna-Mitchell, Ann T, et al.
(författare)
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The impact of neurotrophin-3 on the dorsal root transitional zone following injury
- 2008
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Ingår i: Spinal Cord. - 1362-4393 .- 1476-5624. ; 46:12, s. 804-810
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Tidskriftsartikel (refereegranskat)abstract
- Study design: Morphological and Stereological assessment of the dorsal root transitional zone (DRTZ) following complete crush injury, using light microscopy (LM) and transmission electron microscopy (TEM).Objectives: To assess the effect of exogenous neurotrophin-3 (NT-3) on the response of glial cells and axons to dorsal root damage.Setting: Department of Anatomy, University College Cork, Ireland and Department of Physiology, UMDS, University of London, UK.Methods: Cervical roots (C6-8) from rats which had undergone dorsal root crush axotomy 1 week earlier, in the presence (n = 3) and absence (n = 3) of NT-3, were processed for LM and TEM.Results: Unmyelinated axon number and size was greater in the DRTZ proximal ( Central Nervous System; CNS) and distal ( Peripheral Nervous System; PNS) compartments of NT-3-treated tissue. NT-3 was associated with a reduced astrocytic response, an increase in the proportion of oligodendrocytic tissue and a possible inhibition or delay of microglial activation. Disrupted-myelin volume in the DRTZ PNS and CNS compartments of treated tissue was lower, than in control tissue. In the PNS compartment, NT-3 treatment increased phagocyte and blood vessel numbers. It decreased myelinating activity, as sheath thickness was significantly lower and may also account for the noted lower Schwann cell and organelle volume in the test group.Conclusions: Our observations suggest that NT-3 interacts with non-neuronal tissue to facilitate the regenerative effort of damaged axons. This may be as a consequence of a direct action or indirectly mediated by modulation of non-neuronal responses to injury.
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| 8. |
- Kozlova, Anna P., et al.
(författare)
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Luminescence and vacuum ultraviolet excitation spectroscopy of cerium doped Gd3Ga3Al2O12 single crystalline scintillators under synchrotron radiation excitations
- 2020
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Ingår i: Results in Physics. - : Elsevier BV. - 2211-3797. ; 16
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Tidskriftsartikel (refereegranskat)abstract
- Cerium doped Gd3Ga3Al2O12 (GGAG) single crystals as well as GGAG:Ce single crystals co-doped by divalent (Mg2+, Ca2+), trivalent (Sc3+) or tetravalent (Zr4+, Ti4+) ions have been studied by means of the excitation luminescence spectroscopy in vacuum ultraviolet spectral range. Synchrotron radiation from the undulator beam was utilized for the luminescence excitation in the energy range from 4.5 to 800 eV. The influence of the co-dopant ions on the excitonic transitions as well as on the intrinsic defects in GGAG was revealed examining the luminescence emission and excitation spectra of both Gd3+ and Ce3+ ions in all single crystals studied. Special attention was paid to the analysis of Ce3+ excitation spectra in VUV spectral range (4.5–45 eV) where multiplication of electronic excitation (MEE) processes occur. It was obtained that GGAG:Ce single crystals having different co-dopant ions reveal distinguished efficiency of MEE. The role of intrinsic defects in MEE processes in the co-doped GGAG:Ce single crystals was elucidated.
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