TY - JOUR A1 - Yadav, Himanshu A1 - Husain, Samar A1 - Futrell, Richard T1 - Do dependency lengths explain constraints on crossing dependencies? JF - Linguistics vanguard : multimodal online journal N2 - In syntactic dependency trees, when arcs are drawn from syntactic heads to dependents, they rarely cross. Constraints on these crossing dependencies are critical for determining the syntactic properties of human language, because they define the position of natural language in formal language hierarchies. We study whether the apparent constraints on crossing syntactic dependencies in natural language might be explained by constraints on dependency lengths (the linear distance between heads and dependents). We compare real dependency trees from treebanks of 52 languages against baselines of random trees which are matched with the real trees in terms of their dependency lengths. We find that these baseline trees have many more crossing dependencies than real trees, indicating that a constraint on dependency lengths alone cannot explain the empirical rarity of crossing dependencies. However, we find evidence that a combined constraint on dependency length and the rate of crossing dependencies might be able to explain two of the most-studied formal restrictions on dependency trees: gap degree and well-nestedness. KW - crossing dependencies KW - dependency length KW - dependency treebanks KW - efficiency KW - language processing KW - syntax Y1 - 2021 U6 - https://doi.org/10.1515/lingvan-2019-0070 SN - 2199-174X VL - 7 PB - De Gruyter Mouton CY - Berlin ; New York, NY ER - TY - JOUR A1 - Zhong, Yufei A1 - Causa, Martina A1 - Moore, Gareth John A1 - Krauspe, Philipp A1 - Xiao, Bo A1 - Günther, Florian A1 - Kublitski, Jonas A1 - BarOr, Eyal A1 - Zhou, Erjun A1 - Banerji, Natalie T1 - Sub-picosecond charge-transfer at near-zero driving force in polymer:non-fullerene acceptor blends and bilayers JF - Nature Communications N2 - Organic photovoltaics based on non-fullerene acceptors (NFAs) show record efficiency of 16 to 17% and increased photovoltage owing to the low driving force for interfacial charge-transfer. However, the low driving force potentially slows down charge generation, leading to a tradeoff between voltage and current. Here, we disentangle the intrinsic charge-transfer rates from morphology-dependent exciton diffusion for a series of polymer:NFA systems. Moreover, we establish the influence of the interfacial energetics on the electron and hole transfer rates separately. We demonstrate that charge-transfer timescales remain at a few hundred femtoseconds even at near-zero driving force, which is consistent with the rates predicted by Marcus theory in the normal region, at moderate electronic coupling and at low re-organization energy. Thus, in the design of highly efficient devices, the energy offset at the donor:acceptor interface can be minimized without jeopardizing the charge-transfer rate and without concerns about a current-voltage tradeoff. KW - organic solar cell KW - electron-transfer KW - Donor-Acceptor (DA) interface KW - transfer dynamics KW - donor KW - seperation KW - efficiency KW - impact KW - energy KW - photovoltaics Y1 - 2020 U6 - https://doi.org/10.1038/s41467-020-14549-w SN - 2041-1723 VL - 11 IS - 1 SP - 1 EP - 10 PB - Nature Publishing Group UK CY - London ER - TY - JOUR A1 - Kuhlmann, Sabine A1 - Wayenberg, Ellen T1 - Institutional impact assessment in multi-level systems: conceptualizing decentralization effects from a comparative perspective JF - International review of administrative sciences : an international journal of comparative public administration N2 - Comparative literature on institutional reforms in multi-level systems proceeds from a global trend towards the decentralization of state functions. However, there is only scarce knowledge about the impact that decentralization has had, in particular, upon the sub-central governments involved. How does it affect regional and local governments? Do these reforms also have unintended outcomes on the sub-central level and how can this be explained? This article aims to develop a conceptual framework to assess the impacts of decentralization on the sub-central level from a comparative and policy-oriented perspective. This framework is intended to outline the major patterns and models of decentralization and the theoretical assumptions regarding de-/re-centralization impacts, as well as pertinent cross-country approaches meant to evaluate and compare institutional reforms. It will also serve as an analytical guideline and a structural basis for all the country-related articles in this Special Issue. Points for practitioners Decentralization reforms are approved as having a key role to play in the attainment of ‘good governance’. Yet, there is also the enticement on the part of state governments to offload an ever-increasing amount of responsibilities to, and overtask, local levels of government, which can lead to increasing performance disparities within local sub-state jurisdictions. Against this background, the article provides a conceptual framework to assess reform impacts from a comparative perspective. The analytical framework can be used by practitioners to support their decisions about new decentralization strategies or necessary adjustments regarding ongoing reform measures. KW - administrative reform KW - comparison KW - coordination KW - effectiveness KW - efficiency KW - impact assessment KW - institutional reform KW - local government Y1 - 2016 U6 - https://doi.org/10.1177/0020852315583194 SN - 0020-8523 SN - 1461-7226 VL - 82 IS - 2 SP - 233 EP - 272 PB - Sage CY - London ER -