457 research outputs found
Quantum Fokker-Planck models: the Lindblad and Wigner approaches
In this article we try to bridge the gap between the quantum dynamical
semigroup and Wigner function approaches to quantum open systems. In particular
we study stationary states and the long time asymptotics for the quantum
Fokker-Planck equation. Our new results apply to open quantum systems in a
harmonic confinement potential, perturbed by a (large) sub-quadratic term.Comment: 19 pages, corrected typos and quoted Theorem 6 more precisel
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Ecosystem Service Supply in the Antarctic Peninsula Region: Evaluating an Expert-Based Assessment Approach and a Novel Seascape Data Model
The Southern Ocean and coastal Antarctica provide a variety of ecosystem services with
benefits for humankind that are of regional and global importance. Despite being nearly
uninhabited, increasing exploitation of natural resources, a growing human presence, and
environmental change threaten the sustained provisioning of these services. Ecosystem
service assessments have proven as a suitable tool to understand the relevance
of ecosystems for human well-being and guide decision-making, but the fluid and
transboundary nature of marine ecosystems poses challenges to analyzing ecosystem
services in regions with large marine sections. New methods to objectively assess the
supply of ecosystem services for such realms are needed, and this need is exemplified by
the Antarctic Peninsula region which encompasses rich marine, coastal, and terrestrial
ecosystems but faces growing impacts and needs for taking action. In this study we
applied the matrix method, an expert-based approach that employs a tabular matrix of
ecosystem services and service providing units (SPUs) to elicit expert knowledge and
rate the actual supply of key ecosystems services from the Antarctic Peninsula region.
Further, we tested the applicability of this method on conventional definitions of SPUs
and on objectively defined physico-chemical seascape units for a subset of the study
region. Our results show high variations in the estimated supply of ecosystem services
for the Antarctic Peninsula region, both with respect to the applied data models and in
terms of the assessed service
Elucidating the Role of Microstructure in Thiophosphate Electrolytes – a Combined Experimental and Theoretical Study of β ‐Li 3 PS 4
Solid-state batteries (SSBs) are promising candidates to significantly exceed the energy densities of today\u27s state-of-the-art technology, lithium-ion batteries (LIBs). To enable this advancement, optimizing the solid electrolyte (SE) is the key. β-LiPS (β-LPS) is the most studied member of the LiS-PS family, offering promising properties for implementation in electric vehicles. In this work, the microstructure of this SE and how it influences the electrochemical performance are systematically investigated. To figure this out, four batches of β-LPS electrolyte with different particle size, shape, and porosity are investigated in detail. It is found that differences in pellet porosities mostly originate from single-particle intrinsic features and less from interparticle voids. Surprisingly, the β-LPS electrolyte pellets with the highest porosity and larger particle size not only show the highest ionic conductivity (up to 0.049 mS cm at RT), but also the most stable cycling performance in symmetrical Li cells. This behavior is traced back to the grain boundary resistance. Larger SE particles seem to be more attractive, as their grain boundary contribution is lower than that of denser pellets prepared using smaller β-LPS particles
Effect of the 3D Structure and Grain Boundaries on Lithium Transport in Garnet Solid Electrolytes
Lithium metal anodes are vital enablers for high-energy all-solid-state batteries (ASSBs). To promote ASSBs in practical applications, performance limitations such as the high lithium interface resistance and the grain boundary resistance in the solid electrolyte (SE) need to be understood and reduced by optimization of the cell design. In this work, we use our 3D microstructure-resolved simulation approach combined with a modified grain boundary transport model for the SE to shed some light on the aforementioned limitations in garnet ASSBs. Using high-resolution volume images of the SE electrode sample, we are able to reconstruct the SE microstructure. Using a grain segmentation algorithm, we further distinguish individual grains and account for the influence of the SE grain size and grain boundaries. We focus our simulation work on the trilayer cell architecture, consisting of two porous SE electrodes separated by a dense layer. Even though the highly porous SE electrodes reduce the lithium interface resistance by providing a higher active surface area, the increased electrode tortuosity also reduces the effective ionic conductivity in the SE. We confirm via impedance simulation studies and validation against experimental results that with increasing SE electrode porosity, the lithium transport becomes limited by grain boundaries. We also correlate the area-specific resistance to different lithium infiltration stages in the trilayer cell by spatially resolving the current density distribution. This analysis allows us to suggest a plausible deposition mechanism, and moreover, we identify current density hot spots in the proximity of the dense layer. These hot spots might lead to dendrite formation and long-term cell failure. The joint theoretical and experimental study gives guidelines for cell design and optimization which allow further improvement of the trilayer architecture
Elucidating the Role of Microstructure in Thiophosphate Electrolytes - a Combined Experimental and Theoretical Study of beta-Li3PS4
Solid-state batteries (SSBs) are promising candidates to significantly exceed the energy densities of today's state-of-the-art technology, lithium-ion batteries (LIBs). To enable this advancement, optimizing the solid electrolyte (SE) is the key. β-Li3PS4 (β-LPS) is the most studied member of the Li2S-P2S5 family, offering promising properties for implementation in electric vehicles. In this work, the microstructure of this SE and how it influences the electrochemical performance are systematically investigated. To figure this out, four batches of β-LPS electrolyte with different particle size, shape, and porosity are investigated in detail. It is found that differences in pellet porosities mostly originate from single-particle intrinsic features and less from interparticle voids. Surprisingly, the β-LPS electrolyte pellets with the highest porosity and larger particle size not only show the highest ionic conductivity (up to 0.049 mS cm–1 at RT), but also the most stable cycling performance in symmetrical Li cells. This behavior is traced back to the grain boundary resistance. Larger SE particles seem to be more attractive, as their grain boundary contribution is lower than that of denser pellets prepared using smaller β-LPS particles
Update of the Minimum Information About BIobank Data Sharing (MIABIS) Core Terminology to the 3<sup>rd</sup> Version
Introduction: The Minimum Information About BIobank Data Sharing (MIABIS) is a biobank-specific terminology enabling the sharing of biobank-related data for different purposes across a wide range of database implementations. After 4 years in use and with the first version of the individual-level MIABIS component Sample, Sample donor, and Event, it was necessary to revise the terminology, especially to include biobanks that work more in the data domain than with samples.Materials & Methods: Nine use-cases representing different types of biobanks, studies, and networks participated in the development work. They represent types of data, specific sample types, or levels of organization that were not included earlier in MIABIS. To support our revision of the Biobank entity, we conducted a survey of European biobanks to chart the services they provide. An important stakeholder group for biobanks include researchers as the main users of biobanks. To be able to render MIABIS more researcher-friendly, we collected different sample/data requests to analyze the terminology adjustment needs in detail. During the update process, the Core terminology was iteratively reviewed by a large group of experts until a consensus was reached.Results: With this update, MIABIS was adjusted to encompass data-driven biobanks and to include data collections, while also describing the services and capabilities biobanks offer to their users, besides the retrospective samples. The terminology was also extended to accommodate sample and data collections of nonhuman origin. Additionally, a set of organizational attributes was compiled to describe networks.Discussion: The usability of MIABIS Core v3 was increased by extending it to cover more topics of the biobanking domain. Additionally, the focus was on a more general terminology and harmonization of attributes with the individual-level entities Sample, Sample donor, and Event to keep the overall terminology minimal. With this work, the internal semantics of the MIABIS terminology was improved
Perspektive der Leistungserbringer - Modul 4 des Projekts "Evaluation von Leistungen zur Teilhabe behinderter Menschen am Arbeitsleben - Abschlussbericht"
Der Abschlussbericht zum Projektmodul "Perspektive der Leistungserbringer" betrachtet den Prozess der beruflichen Rehabilitation aus Sicht der Leistungserbringer. Dabei wird ein gemischt-methodisches Forschungsdesign verwendet. Im Rahmen des Berichts werden die Leistungserbringer näher charakterisiert und interne sowie externe Organisationsprozesse dargestellt. Des Weiteren wird die Zusammenarbeit mit der Bundesagentur für Arbeit und mit den Betrieben näher beleuchtet. Schließlich werden aktuelle Herausforderungen der Leistungserbringer betrachtet und unterschiedliche Definitionen von Maßnahmeerfolg.The report "Perspectives of Rehabilitation Providers" looks at the organization of the process of occupational rehabilitation from the perspective of rehabilitation providers using a mixed-methods approach. It presents main characteristics of providers and the internal and external organization of the rehabilitation process. Furthermore, main aspects of the joint work of rehabilitation providers with the Federal Employment Agency and employers are discussed. Finally, main provider-specific challenges and approaches to define successful rehabilitation are provided
Higgs Bundles, Gauge Theories and Quantum Groups
The appearance of the Bethe Ansatz equation for the Nonlinear Schr\"{o}dinger
equation in the equivariant integration over the moduli space of Higgs bundles
is revisited. We argue that the wave functions of the corresponding
two-dimensional topological U(N) gauge theory reproduce quantum wave functions
of the Nonlinear Schr\"{o}dinger equation in the -particle sector. This
implies the full equivalence between the above gauge theory and the
-particle sub-sector of the quantum theory of Nonlinear Schr\"{o}dinger
equation. This also implies the explicit correspondence between the gauge
theory and the representation theory of degenerate double affine Hecke algebra.
We propose similar construction based on the gauged WZW model leading to
the representation theory of the double affine Hecke algebra. The relation with
the Nahm transform and the geometric Langlands correspondence is briefly
discussed.Comment: 48 pages, typos corrected, one reference adde
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