@article{CsehKavitha2021, author = {Cseh, {\´A}gnes and Kavitha, Telikepalli}, title = {Popular matchings in complete graphs}, series = {Algorithmica : an international journal in computer science}, volume = {83}, journal = {Algorithmica : an international journal in computer science}, number = {5}, publisher = {Springer}, address = {New York}, issn = {0178-4617}, doi = {10.1007/s00453-020-00791-7}, pages = {1493 -- 1523}, year = {2021}, abstract = {Our input is a complete graph G on n vertices where each vertex has a strict ranking of all other vertices in G. The goal is to construct a matching in G that is popular. A matching M is popular if M does not lose a head-to-head election against any matching M ': here each vertex casts a vote for the matching in {M,M '} in which it gets a better assignment. Popular matchings need not exist in the given instance G and the popular matching problem is to decide whether one exists or not. The popular matching problem in G is easy to solve for odd n. Surprisingly, the problem becomes NP-complete for even n, as we show here. This is one of the few graph theoretic problems efficiently solvable when n has one parity and NP-complete when n has the other parity.}, language = {en} } @article{MuellerNeugebauerBenDoretal.2022, author = {M{\"u}ller, Daniela and Neugebauer, Ina and Ben Dor, Yoav and Enzel, Yehouda and Schwab, Markus Julius and Tjallingii, Rik and Brauer, Achim}, title = {Phases of stability during major hydroclimate change ending the Last Glacial in the Levant}, series = {Scientific reports}, volume = {12}, journal = {Scientific reports}, number = {1}, publisher = {Macmillan Publishers Limited, part of Springer Nature}, address = {London}, issn = {2045-2322}, doi = {10.1038/s41598-022-10217-9}, pages = {12}, year = {2022}, abstract = {In-depth understanding of the reorganization of the hydrological cycle in response to global climate change is crucial in highly sensitive regions like the eastern Mediterranean, where water availability is a major factor for socioeconomic and political development. The sediments of Lake Lisan provide a unique record of hydroclimatic change during the last glacial to Holocene transition (ca. 24-11 ka) with its tremendous water level drop of similar to 240 m that finally led to its transition into the present hypersaline water body-the Dead Sea. Here we utilize high-resolution sedimentological analyses from the marginal terraces and deep lake to reconstruct an unprecedented seasonal record of the last millennia of Lake Lisan. Aragonite varve formation in intercalated intervals of our record demonstrates that a stepwise long-term lake level decline was interrupted by almost one millennium of rising or stable water level. Even periods of pronounced water level drops indicated by gypsum deposition were interrupted by decades of positive water budgets. Our results thus highlight that even during major climate change at the end of the last glacial, decadal to millennial periods of relatively stable or positive moisture supply occurred which could have been an important premise for human sedentism.}, language = {en} } @article{ChangKhalilSchulze2021, author = {Chang, Der-Chen and Khalil, Sara and Schulze, Bert-Wolfgang}, title = {Analysis on regular corner spaces}, series = {The journal of geometric analysis}, volume = {31}, journal = {The journal of geometric analysis}, number = {9}, publisher = {Springer}, address = {New York}, issn = {1050-6926}, doi = {10.1007/s12220-021-00614-3}, pages = {9199 -- 9240}, year = {2021}, abstract = {We establish a new approach of treating elliptic boundary value problems (BVPs) on manifolds with boundary and regular corners, up to singularity order 2. Ellipticity and parametrices are obtained in terms of symbols taking values in algebras of BVPs on manifolds of corresponding lower singularity orders. Those refer to Boutet de Monvel's calculus of operators with the transmission property, see Boutet de Monvel (Acta Math 126:11-51, 1971) for the case of smooth boundary. On corner configuration operators act in spaces with multiple weights. We mainly study the case of upper left entries in the respective 2 x 2 operator block-matrices of such a calculus. Green operators in the sense of Boutet de Monvel (Acta Math 126:11-51, 1971) analogously appear in singular cases, and they are complemented by contributions of Mellin type. We formulate a result on ellipticity and the Fredholm property in weighted corner spaces, with parametrices of analogous kind.}, language = {en} } @article{CohenKrauseAbouChadi2024, author = {Cohen, Denis and Krause, Werner and Abou-Chadi, Tarik}, title = {Comparative vote switching}, series = {The journal of politics}, volume = {86}, journal = {The journal of politics}, number = {2}, publisher = {University of Chicago Press}, address = {Chicago, IL}, issn = {0022-3816}, doi = {10.1086/726952}, pages = {597 -- 607}, year = {2024}, abstract = {Large literatures focus on voter reactions to parties' policy strategies, agency, or legislative performance. While many inquiries make explicit assumptions about the direction and magnitude of voter flows between parties, comparative empirical analyses of vote switching remain rare. In this article, we overcome three challenges that have previously impeded the comparative study of dynamic party competition based on voter flows: we present a novel conceptual framework for studying voter retention, defection, and attraction in multiparty systems, showcase a newly compiled data infrastructure that marries comparative vote switching data with information on party behavior and party systems in over 250 electoral contexts, and introduce a statistical model that renders our conceptual framework operable. These innovations enable first-time inquiries into the polyadic vote switching patterns underlying multiparty competition and unlock major research potentials on party competition and party system change.}, language = {en} } @article{KrauseGahn2023, author = {Krause, Werner and Gahn, Christina}, title = {Should we include margins of error in public opinion polls?}, series = {European journal of political research}, volume = {Early view}, journal = {European journal of political research}, publisher = {Wiley-Blackwell}, address = {Oxford}, issn = {0304-4130}, doi = {10.1111/1475-6765.12633}, pages = {26}, year = {2023}, abstract = {Public opinion polls have become vital and increasingly visible parts of election campaigns. Previous research has frequently demonstrated that polls can influence both citizens' voting intentions and political parties' campaign strategies. However, they are also fraught with uncertainty. Margins of error can reflect (parts of) this uncertainty. This paper investigates how citizens' voting intentions change due to whether polling estimates are presented with or without margins of error. Using a vignette experiment (N=3224), we examine this question based on a real-world example in which different election polls were shown to nationally representative respondents ahead of the 2021 federal election in Germany. We manipulated the display of the margins of error, the interpretation of polls and the closeness of the electoral race. The results indicate that margins of error can influence citizens' voting intentions. This effect is dependent on the actual closeness of the race and additional interpretative guidance provided to voters. More concretely, the results consistently show that margins of error increase citizens' inclination to vote for one of the two largest contesting parties if the polling gap between these parties is small, and an interpretation underlines this closeness. The findings of this study are important for three reasons. First, they help to determine whether margins of error can assist citizens in making more informed (strategic) vote decisions. They shed light on whether depicting opinion-poll uncertainty affects the key features of representative democracy, such as democratic accountability. Second, the results stress the responsibility of the media. The way polls are interpreted and contextualized influences the effect of margins of error on voting behaviour. Third, the findings of this paper underscore the significance of including methodological details when communicating scientific research findings to the broader public.}, language = {en} } @article{JagtianiWellek2022, author = {Jagtiani, Sharinee L. and Wellek, Sophia}, title = {In the Shadow of Ukraine}, series = {Survival}, volume = {64}, journal = {Survival}, number = {3}, publisher = {Routledge, Taylor \& Francis Group}, address = {Abingdon}, issn = {126962024X}, doi = {10.1080/00396338.2022.2078045}, pages = {29 -- 48}, year = {2022}, abstract = {In 2022, India captured global attention over its response to the war in Ukraine. While calling for both parties' return to diplomacy, India abstained from several United Nations resolutions condemning Russian aggression. For a country that ostensibly subscribes to the values of democracy and territorial integrity, its response appeared frustrating and contradictory, but it is broadly consistent with its long-standing policy of non-alignment. Although India's relationship with China is increasingly contentious, New Delhi is not yet fully convinced that it is in India's interest to swing westwards. The country's relations with Russia and China are deep, complex and substantive. In addition to the military and economic benefits it derives from its connection with Russia, New Delhi and Moscow share an avowed preference for a more equal, multipolar world. India will eventually have to reflect on the extent to which it can sustain its balancing act.}, language = {en} } @article{KurilovichMantsevichMardoukhietal.2022, author = {Kurilovich, Aleksandr A. and Mantsevich, Vladimir N. and Mardoukhi, Yousof and Stevenson, Keith J. and Chechkin, Aleksei and Palyulin, Vladimir V.}, title = {Non-Markovian diffusion of excitons in layered perovskites and transition metal dichalcogenides}, series = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, volume = {24}, journal = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, number = {22}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1463-9076}, doi = {10.1039/d2cp00557c}, pages = {13941 -- 13950}, year = {2022}, abstract = {The diffusion of excitons in perovskites and transition metal dichalcogenides shows clear anomalous, subdiffusive behaviour in experiments. In this paper we develop a non-Markovian mobile-immobile model which provides an explanation of this behaviour through paired theoretical and simulation approaches. The simulation model is based on a random walk on a 2D lattice with randomly distributed deep traps such that the trapping time distribution involves slowly decaying power-law asymptotics. The theoretical model uses coupled diffusion and rate equations for free and trapped excitons, respectively, with an integral term responsible for trapping. The model provides a good fitting of the experimental data, thus, showing a way for quantifying the exciton diffusion dynamics.}, language = {en} } @article{GrischekCaprioglioZhangetal.2022, author = {Grischek, Max and Caprioglio, Pietro and Zhang, Jiahuan and Pena-Camargo, Francisco and Sveinbjornsson, Kari and Zu, Fengshuo and Menzel, Dorothee and Warby, Jonathan H. and Li, Jinzhao and Koch, Norbert and Unger, Eva and Korte, Lars and Neher, Dieter and Stolterfoht, Martin and Albrecht, Steve}, title = {Efficiency Potential and Voltage Loss of Inorganic CsPbI2Br Perovskite Solar Cells}, series = {Solar RRL}, volume = {6}, journal = {Solar RRL}, number = {11}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {2367-198X}, doi = {10.1002/solr.202200690}, pages = {12}, year = {2022}, abstract = {Inorganic perovskite solar cells show excellent thermal stability, but the reported power conversion efficiencies are still lower than for organic-inorganic perovskites. This is mainly caused by lower open-circuit voltages (V(OC)s). Herein, the reasons for the low V-OC in inorganic CsPbI2Br perovskite solar cells are investigated. Intensity-dependent photoluminescence measurements for different layer stacks reveal that n-i-p and p-i-n CsPbI2Br solar cells exhibit a strong mismatch between quasi-Fermi level splitting (QFLS) and V-OC. Specifically, the CsPbI2Br p-i-n perovskite solar cell has a QFLS-e center dot V-OC mismatch of 179 meV, compared with 11 meV for a reference cell with an organic-inorganic perovskite of similar bandgap. On the other hand, this study shows that the CsPbI2Br films with a bandgap of 1.9 eV have a very low defect density, resulting in an efficiency potential of 20.3\% with a MeO-2PACz hole-transporting layer and 20.8\% on compact TiO2. Using ultraviolet photoelectron spectroscopy measurements, energy level misalignment is identified as a possible reason for the QFLS-e center dot V-OC mismatch and strategies for overcoming this V-OC limitation are discussed. This work highlights the need to control the interfacial energetics in inorganic perovskite solar cells, but also gives promise for high efficiencies once this issue is resolved.}, language = {en} } @article{CaiToetzkeKaestneretal.2022, author = {Cai, Gaochao and T{\"o}tzke, Christian and Kaestner, Anders and Ahmed, Mutez Ali}, title = {Quantification of root water uptake and redistribution using neutron imaging: a review and future directions}, series = {The plant journal}, volume = {111}, journal = {The plant journal}, number = {2}, publisher = {Wiley-Blackwell}, address = {Oxford [u.a.]}, issn = {0960-7412}, doi = {10.1111/tpj.15839}, pages = {348 -- 359}, year = {2022}, abstract = {Quantifying root water uptake is essential to understanding plant water use and responses to different environmental conditions. However, non-destructive measurement of water transport and related hydraulics in the soil-root system remains a challenge. Neutron imaging, with its high sensitivity to hydrogen, has become an unparalleled tool to visualize and quantify root water uptake in vivo. In combination with isotopes (e.g., deuterated water) and a diffusion-convection model, root water uptake and hydraulic redistribution in root and soil can be quantified. Here, we review recent advances in utilizing neutron imaging to visualize and quantify root water uptake, hydraulic redistribution in roots and soil, and root hydraulic properties of different plant species. Under uniform soil moisture distributions, neutron radiographic studies have shown that water uptake was not uniform along the root and depended on both root type and age. For both tap (e.g., lupine [Lupinus albus L.]) and fibrous (e.g., maize [Zea mays L.]) root systems, water was mainly taken up through lateral roots. In mature maize, the location of water uptake shifted from seminal roots and their laterals to crown/nodal roots and their laterals. Under non-uniform soil moisture distributions, part of the water taken up during the daytime maintained the growth of crown/nodal roots in the upper, drier soil layers. Ultra-fast neutron tomography provides new insights into 3D water movement in soil and roots. We discuss the limitations of using neutron imaging and propose future directions to utilize neutron imaging to advance our understanding of root water uptake and soil-root interactions.}, language = {en} } @article{Marienfeldt2024, author = {Marienfeldt, Justine}, title = {Does digital government hollow out the essence of street-level bureaucracy?}, series = {Social policy \& administration}, journal = {Social policy \& administration}, publisher = {Wiley-Blackwell}, address = {Oxford}, issn = {0144-5596}, doi = {10.1111/spol.12991}, pages = {1 -- 25}, year = {2024}, abstract = {The growing use of digital tools in policy implementation has altered the work of street-level bureaucrats who are granted substantial discretionary power in decision-making. Digital tools can constrain discretionary power, like the curtailment thesis proposed, or serve as action resources, like the enablement thesis suggested. This article assesses empirical evidence of the impact of digital tools on street-level work and decision-making in service-oriented and regulation-oriented organisations based on a systematic literature review and thematic qualitative content analysis of 36 empirical studies published until 2021. The findings demonstrate different effects with regard to the role of digital tools and the core tasks of the public administration, depending on political and managerial goals and consequent system design. Leading or decisive digital tools mostly curtail discretion, especially in service-oriented organisations. In contrast, an enhanced information base or recommendations for actions enable decision-making, in particular in regulation-oriented organisations. By showing how street-level bureaucrats actively try to resist the curtailing effects caused by rigid design to address individual circumstances, for instance by establishing ways of coping like rule bending or rule breaking, using personal resources or prioritising among clients, this study demonstrates the importance of the continuation thesis and the persistently crucial role of human judgement in policy implementation.}, language = {en} }