| 1. |
- Arridge, Christopher S., et al.
(författare)
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Uranus Pathfinder : exploring the origins and evolution of Ice Giant planets
- 2012
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Ingår i: Experimental astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 33:2-3, s. 753-791
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Tidskriftsartikel (refereegranskat)abstract
- The "Ice Giants" Uranus and Neptune are a different class of planet compared to Jupiter and Saturn. Studying these objects is important for furthering our understanding of the formation and evolution of the planets, and unravelling the fundamental physical and chemical processes in the Solar System. The importance of filling these gaps in our knowledge of the Solar System is particularly acute when trying to apply our understanding to the numerous planetary systems that have been discovered around other stars. The Uranus Pathfinder (UP) mission thus represents the quintessential aspects of the objectives of the European planetary community as expressed in ESA's Cosmic Vision 2015-2025. UP was proposed to the European Space Agency's M3 call for medium-class missions in 2010 and proposed to be the first orbiter of an Ice Giant planet. As the most accessible Ice Giant within the M-class mission envelope Uranus was identified as the mission target. Although not selected for this call the UP mission concept provides a baseline framework for the exploration of Uranus with existing low-cost platforms and underlines the need to develop power sources suitable for the outer Solar System. The UP science case is based around exploring the origins, evolution, and processes at work in Ice Giant planetary systems. Three broad themes were identified: (1) Uranus as an Ice Giant, (2) An Ice Giant planetary system, and (3) An asymmetric magnetosphere. Due to the long interplanetary transfer from Earth to Uranus a significant cruise-phase science theme was also developed. The UP mission concept calls for the use of a Mars Express/Rosetta-type platform to launch on a Soyuz-Fregat in 2021 and entering into an eccentric polar orbit around Uranus in the 2036-2037 timeframe. The science payload has a strong heritage in Europe and beyond and requires no significant technology developments.
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| 2. |
- Adnan, Md Mohsinur Rahman, et al.
(författare)
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Anisotropic Beer-Lambert law in β - Ga2 O3 : Polarization-dependent absorption and photoresponsivity spectra
- 2024
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Ingår i: Physical Review Applied. - 2331-7019. ; 21:5
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Tidskriftsartikel (refereegranskat)abstract
- Due to its low symmetry, β-Ga2O3 exhibits a strongly anisotropic optical response. As a result, the absorption spectra change with the polarization state of the incoming photons. To understand this phenomenon, here we calculate the complete electromagnetic wave equation solutions as a function of linear polarization angle and photon energy for β-Ga2O3 using its previously measured complex dielectric function tensor. The significant off-diagonal terms in this tensor can result in a nonexponential decay in the photon flux, indicating that the Beer-Lambert law is not generally valid in this anisotropic material. However, for above-band-gap spectral regions that depend on crystallographic orientations [>5.8 eV (001-plane) and >5.2 eV (010-plane)], an effective absorption coefficient closely approximates the photon flux decay with depth. On the other hand, near the optical absorption edge [4.9-5.8 eV (001-plane) and 4.65-5.2 eV (010-plane)], the photon flux decay exhibits a sum of two exponential decays, such that two effective absorption coefficients are necessary to model the loss behavior versus the absorption depth. This behavior manifests from the presence of dichroism in β-Ga2O3. A single effective absorption coefficient can only be recovered for this energy range by augmenting the isotropic Beer-Lambert law with a critical penetration depth and polarization dependence. Using these results, we calculate the polarization-dependent photoresponsivity spectra for light polarized along different crystallographic directions.
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| 3. |
- David, Romain, et al.
(författare)
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Converging on a Semantic Interoperability Framework for the European Data Space for Science, Research and Innovation (EOSC)
- 2023
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Konferensbidrag (refereegranskat)abstract
- Semantic interoperability (SI) is at the heart of the FAIR principles and of the design of large scale cross disciplinary infrastructures. The European Open Science Cloud (EOSC) is a European-wide effort towards such an infrastructure, aiming to deepen the regional research collaboration and realising a shared data space for science, research and innovation. In this context, the research community’s voice is represented by the EOSC Association (EOSC-A) and a number of advisory groups with a broad range of representatives from different stakeholder organisations. The advisory group on metadata and data quality has formed a task force focusing on developing and implementing recommendations for SI (EOSC SI Task Force) with the ambition to converge on globally relevant and scalable SI solutions for EOSC. This paper provides context to SI in EOSC, the various components contributing to it, as well as some views on the socio-technical challenges to arriving at a consensus. In particular, the paper provides motivation for exploring the heterogeneity of SI solutions demonstrated across scientific communities and insight into the task force’s planned approach to conduct a survey to identify relevant components and structures. The paper is also an invitation to the global community to align and engage with the task force’s activities going forward.
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| 4. |
- Mollenhauer, Brit, et al.
(författare)
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Antibody-based methods for the measurement of α-synuclein concentration in human cerebrospinal fluid - method comparison and round robin study.
- 2019
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Ingår i: Journal of neurochemistry. - : Wiley. - 1471-4159 .- 0022-3042. ; 149:1, s. 126-138
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Tidskriftsartikel (refereegranskat)abstract
- α-Synuclein is the major component of Lewy bodies and a candidate biomarker for neurodegenerative diseases in which Lewy bodies are common, including Parkinson's disease and dementia with Lewy bodies. A large body of literature suggests that these disorders are characterized by reduced concentrations of α-synuclein in cerebrospinal fluid (CSF), with overlapping concentrations compared to healthy controls and variability across studies. Several reasons can account for this variability, including technical ones, such as inter-assay and inter-laboratory variation (reproducibility). We compared four immunochemical methods for the quantification of α-synuclein concentration in 50 unique CSF samples. All methods were designed to capture most of the existing α-synuclein forms in CSF ('total' α-synuclein). Each of the four methods showed high analytical precision, excellent correlation between laboratories (R2 0.83-0.99), and good correlation with each other (R2 0.64-0.93), although the slopes of the regression lines were different between the four immunoassays. The use of common reference CSF samples decreased the differences in α-synuclein concentration between detection methods and technologies. Pilot data on an immunoprecipitation mass spectrometry (IP-MS) method isalso presented. Our results suggest that the four immunochemical methods and the IP-MS method measure similarforms of α-synuclein and that a common reference materialwould allow harmonization of results between immunoassays.
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| 5. |
- Poppi, Stefano, et al.
(författare)
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Simulation study of cascade heat pump for solar combisystems
- 2014
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Ingår i: ISES Conference Proceedings EuroSun 2014. - : International Solar Energy Society (ISES).
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper focuses on the study of cascade heat pump systems in combination with solar thermal for the production of hot water and space heating in single family houses with relatively high heating demand. The system concept was developed by Ratiotherm GmbH and simulated with TRNSYS 17. The basic cascade system uses the heat pump and solar collectors in parallel operation while a further development is the inclusion of an intermediate store that enables the possibility of serial/parallel operation and the use of low temperature solar heat. Parametric studies in terms of compressor size, refrigerant pair and size of intermediate heat exchanger were carried out for the optimization of the basic system. The system configurations were simulated for the complete year and compared to a reference of a solar thermal system combined with an air source heat pump. The results show ~13% savings in electricity use for all three cascade systems compared to the reference. However, the complexity of the systems is different and thus higher capital costs are expected.
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| 6. |
- Richter, Steffen, et al.
(författare)
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High-field/high-frequency electron spin resonances of Fe-doped β-Ga2 O3 by terahertz generalized ellipsometry : Monoclinic symmetry effects
- 2024
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Ingår i: Physical Review B. - 2469-9950. ; 109:21
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate detection and measurement of electron paramagnetic spin resonances (EPR) of iron defects in β-Ga2O3 utilizing generalized ellipsometry at frequencies between 110 and 170 GHz. The experiments are performed on an Fe-doped single crystal in a free-beam configuration in reflection at 45∘ and magnetic fields between 3 and 7 T. In contrast with low-field, low-frequency EPR measurements, we observe all five transitions of the s=5/2 high-spin state Fe3+ simultaneously. We confirm that ferric Fe3+ is predominantly found at octahedrally coordinated Ga sites. We obtain the full set of fourth-order monoclinic zero-field splitting parameters for both octahedrally and tetrahedrally coordinated sites by employing measurements at multiple sample azimuth rotations. The capability of high-field EPR allows us to demonstrate that simplified second-order orthorhombic spin Hamiltonians are insufficient, and fourth-order terms as well as consideration of the monoclinic symmetry are needed. These findings are supported by computational approaches based on density-functional theory for second-order and on ligand-field theory for fourth-order parameters of the spin Hamiltonian. Terahertz ellipsometry is a way to measure spin resonances in a cavity-free setup. Its possibility of varying the probe frequency arbitrarily without otherwise changing the experimental setup offers unique means of truly disentangling different components of highly anisotropic spin Hamiltonians.
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