@article{DzhanoevSchmidtLiuetal.2016, author = {Dzhanoev, Arsen R. and Schmidt, J. and Liu, X. and Spahn, Frank}, title = {Charging of small grains in a space plasma: Application to Jovian stream particles}, series = {International psychogeriatrics}, volume = {591}, journal = {International psychogeriatrics}, publisher = {EDP Sciences}, address = {Les Ulis}, issn = {1432-0746}, doi = {10.1051/0004-6361/201527891}, pages = {647 -- 684}, year = {2016}, abstract = {Context. Most theoretical investigations of dust charging processes in space have treated the current balance condition as independent of grain size. However, for small grains, since they are often observed in space environments, a dependence on grain size is expected owing to secondary electron emission (SEE). Here, by the term "small" we mean a particle size comparable to the typical penetration depth for given primary electron energy. The results are relevant for the dynamics of small, charged dust particles emitted by the volcanic moon Io, which forms the Jovian dust streams. Aims. We revise the theory of charging of small (submicron sized) micrometeoroids to take into account a high production of secondary electrons for small grains immersed in an isotropic flux of electrons. We apply our model to obtain an improved estimate for the charge of the dust streams leaving the Jovian system, detected by several spacecraft. Methods. We apply a continuum model to describe the penetration of primary electrons in a grain and the emission of secondary electrons along the path. Averaging over an isotropic flux of primaries, we derive a new expression for the secondary electron yield, which can be used to express the secondary electron current on a grain. Results. For the Jupiter plasma environment we derive the surface potential of grains composed of NaCl (believed to be the major constituent of Jovian dust stream particles) or silicates. For small particles, the potential depends on grain size and the secondary electron current induces a sensitivity to material properties. As a result of the small particle effect, the estimates for the charging times and for the fractional charge fluctuations of NaCl grains obtained using our general approach to SEE give results qualitatively different from the analogous estimates derived from the traditional approach to SEE. We find that for the charging environment considered in this paper field emission does not limit the charging of NaCl grains.}, language = {en} } @article{YanXueJiangetal.2022, author = {Yan, Xiaoli and Xue, Zhike and Jiang, Chaowei and Priest, E. R. and Kliem, Bernhard and Yang, Liheng and Wang, Jincheng and Kong, Defang and Song, Yongliang and Feng, Xueshang and Liu, Zhong}, title = {Fast plasmoid-mediated reconnection in a solar flare}, series = {Nature Communications}, volume = {13}, journal = {Nature Communications}, number = {1}, publisher = {Nature Publishing Group UK}, address = {London}, issn = {2041-1723}, doi = {10.1038/s41467-022-28269-w}, pages = {14}, year = {2022}, abstract = {Magnetic reconnection is a multi-faceted process of energy conversion in astrophysical, space and laboratory plasmas that operates at microscopic scales but has macroscopic drivers and consequences. Solar flares present a key laboratory for its study, leaving imprints of the microscopic physics in radiation spectra and allowing the macroscopic evolution to be imaged, yet a full observational characterization remains elusive. Here we combine high resolution imaging and spectral observations of a confined solar flare at multiple wavelengths with data-constrained magnetohydrodynamic modeling to study the dynamics of the flare plasma from the current sheet to the plasmoid scale. The analysis suggests that the flare resulted from the interaction of a twisted magnetic flux rope surrounding a filament with nearby magnetic loops whose feet are anchored in chromospheric fibrils. Bright cusp-shaped structures represent the region around a reconnecting separator or quasi-separator (hyperbolic flux tube). The fast reconnection, which is relevant for other astrophysical environments, revealed plasmoids in the current sheet and separatrices and associated unresolved turbulent motions. Solar flares provide wide range of observational details about fundamental processes involved. Here, the authors show evidence for magnetic reconnection in a strong confined solar flare displaying all four reconnection flows with plasmoids in the current sheet and the separatrices.}, language = {en} } @misc{LiuTkachovKomberetal.2014, author = {Liu, W. and Tkachov, R. and Komber, H. and Senkovskyy, V. and Schubert, M. and Wei, Z. and Facchetti, A. and Neher, Dieter and Kiriy, A.}, title = {Chain-growth polycondensation of perylene diimide-based copolymers}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-98724}, pages = {8}, year = {2014}, abstract = {Herein, we report the chain-growth tin-free room temperature polymerization method to synthesize n-type perylene diimide-dithiophene-based conjugated polymers (PPDIT2s) suitable for solar cell and transistor applications. The palladium/electron-rich tri-tert-butylphosphine catalyst is effective to enable the chain-growth polymerization of anion-radical monomer Br-TPDIT-Br/Zn to PPDIT2 with a molecular weight up to Mw ≈ 50 kg mol-1 and moderate polydispersity. This is the second example of the polymerization of unusual anion-radical aromatic complexes formed in a reaction of active Zn and electron-deficient diimide-based aryl halides. As such, the discovered polymerization method is not a specific reactivity feature of the naphthalene-diimide derivatives but is rather a general polymerization tool. This is an important finding, given the significantly higher maximum external quantum efficiency that can be reached with PDI-based copolymers (32-45\%) in all-polymer solar cells compared to NDI-based materials (15-30\%). Our studies revealed that PPDIT2 synthesized by the new method and the previously published polymer prepared by step-growth Stille polycondensation show similar electron mobility and all-polymer solar cell performance. At the same time, the polymerization reported herein has several technological advantages as it proceeds relatively fast at room temperature and does not involve toxic tin-based compounds. Because several chain-growth polymerization reactions are well-suited for the preparation of well-defined multi-functional polymer architectures, the next target is to explore the utility of the discovered polymerization in the synthesis of end-functionalized polymers and block copolymers. Such materials would be helpful to improve the nanoscale morphology of polymer blends in all-polymer solar cells.}, language = {en} } @article{LiuTkachovKomberetal.2014, author = {Liu, W. and Tkachov, R. and Komber, H. and Senkovskyy, V. and Schubert, M. and Wei, Z. and Facchetti, A. and Neher, Dieter and Kiriy, A.}, title = {Chain-growth polycondensation of perylene diimide-based copolymers: a new route to regio-regular perylene diimide-based acceptors for all-polymer solar cells and n-type transistors}, series = {Polymer Chemistry}, volume = {5}, journal = {Polymer Chemistry}, number = {10}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1759-9954}, doi = {10.1039/c3py01707a}, pages = {3404 -- 3411}, year = {2014}, abstract = {Herein, we report the chain-growth tin-free room temperature polymerization method to synthesize n-type perylene diimide-dithiophene-based conjugated polymers (PPDIT2s) suitable for solar cell and transistor applications. The palladium/electron-rich tri-tert-butylphosphine catalyst is effective to enable the chain-growth polymerization of anion-radical monomer Br-TPDIT-Br/Zn to PPDIT2 with a molecular weight up to M-w approximate to 50 kg mol(-1) and moderate polydispersity. This is the second example of the polymerization of unusual anion-radical aromatic complexes formed in a reaction of active Zn and electron-deficient diimide-based aryl halides. As such, the discovered polymerization method is not a specific reactivity feature of the naphthalene-diimide derivatives but is rather a general polymerization tool. This is an important finding, given the significantly higher maximum external quantum efficiency that can be reached with PDI-based copolymers (32-45\%) in all-polymer solar cells compared to NDI-based materials (15-30\%). Our studies revealed that PPDIT2 synthesized by the new method and the previously published polymer prepared by step-growth Stille polycondensation show similar electron mobility and all-polymer solar cell performance. At the same time, the polymerization reported herein has several technological advantages as it proceeds relatively fast at room temperature and does not involve toxic tin-based compounds. Because several chain-growth polymerization reactions are well-suited for the preparation of well-defined multi-functional polymer architectures, the next target is to explore the utility of the discovered polymerization in the synthesis of end-functionalized polymers and block copolymers. Such materials would be helpful to improve the nanoscale morphology of polymer blends in all-polymer solar cells.}, language = {en} } @article{CourtinAndreevRaschkeetal.2021, author = {Courtin, J{\´e}r{\´e}my and Andreev, Andrei and Raschke, Elena and Bala, Sarah and Biskaborn, Boris and Liu, Sisi and Zimmermann, Heike and Diekmann, Bernhard and Stoof-Leichsenring, Kathleen R. and Pestryakova, Luidmila Agafyevna and Herzschuh, Ulrike}, title = {Vegetation changes in Southeastern Siberia during the late pleistocene and the holocene}, series = {Frontiers in Ecology and Evolution}, volume = {9}, journal = {Frontiers in Ecology and Evolution}, publisher = {Frontiers Media}, address = {Lausanne}, issn = {2296-701X}, doi = {10.3389/fevo.2021.625096}, pages = {18}, year = {2021}, abstract = {Relationships between climate, species composition, and species richness are of particular importance for understanding how boreal ecosystems will respond to ongoing climate change. This study aims to reconstruct changes in terrestrial vegetation composition and taxa richness during the glacial Late Pleistocene and the interglacial Holocene in the sparsely studied southeastern Yakutia (Siberia) by using pollen and sedimentary ancient DNA (sedaDNA) records. Pollen and sedaDNA metabarcoding data using the trnL g and h markers were obtained from a sediment core from Lake Bolshoe Toko. Both proxies were used to reconstruct the vegetation composition, while metabarcoding data were also used to investigate changes in plant taxa richness. The combination of pollen and sedaDNA approaches allows a robust estimation of regional and local past terrestrial vegetation composition around Bolshoe Toko during the last similar to 35,000 years. Both proxies suggest that during the Late Pleistocene, southeastern Siberia was covered by open steppe-tundra dominated by graminoids and forbs with patches of shrubs, confirming that steppe-tundra extended far south in Siberia. Both proxies show disturbance at the transition between the Late Pleistocene and the Holocene suggesting a period with scarce vegetation, changes in the hydrochemical conditions in the lake, and in sedimentation rates. Both proxies document drastic changes in vegetation composition in the early Holocene with an increased number of trees and shrubs and the appearance of new tree taxa in the lake's vicinity. The sedaDNA method suggests that the Late Pleistocene steppe-tundra vegetation supported a higher number of terrestrial plant taxa than the forested Holocene. This could be explained, for example, by the "keystone herbivore" hypothesis, which suggests that Late Pleistocene megaherbivores were able to maintain a high plant diversity. This is discussed in the light of the data with the broadly accepted species-area hypothesis as steppe-tundra covered such an extensive area during the Late Pleistocene.}, language = {en} } @article{HuangStoofLeichsenringLiuetal.2021, author = {Huang, Sichao and Stoof-Leichsenring, Kathleen R. and Liu, Sisi and Courtin, Jeremy and Andreev, Andrej A. and Pestryakova, Luidmila. A. and Herzschuh, Ulrike}, title = {Plant sedimentary ancient DNA from Far East Russia covering the last 28,000 years reveals different assembly rules in cold and warm climates}, series = {Frontiers in Ecology and Evolution}, volume = {9}, journal = {Frontiers in Ecology and Evolution}, publisher = {Frontiers Media}, address = {Lausanne}, issn = {2296-701X}, doi = {10.3389/fevo.2021.763747}, pages = {15}, year = {2021}, abstract = {Woody plants are expanding into the Arctic in response to the warming climate. The impact on arctic plant communities is not well understood due to the limited knowledge about plant assembly rules. Records of past plant diversity over long time series are rare. Here, we applied sedimentary ancient DNA metabarcoding targeting the P6 loop of the chloroplast trnL gene to a sediment record from Lake Ilirney (central Chukotka, Far Eastern Russia) covering the last 28 thousand years. Our results show that forb-rich steppe-tundra and dwarf-shrub tundra dominated during the cold climate before 14 ka, while deciduous erect-shrub tundra was abundant during the warm period since 14 ka. Larix invasion during the late Holocene substantially lagged behind the likely warmest period between 10 and 6 ka, where the vegetation biomass could be highest. We reveal highest richness during 28-23 ka and a second richness peak during 13-9 ka, with both periods being accompanied by low relative abundance of shrubs. During the cold period before 14 ka, rich plant assemblages were phylogenetically clustered, suggesting low genetic divergence in the assemblages despite the great number of species. This probably originates from environmental filtering along with niche differentiation due to limited resources under harsh environmental conditions. In contrast, during the warmer period after 14 ka, rich plant assemblages were phylogenetically overdispersed. This results from a high number of species which were found to harbor high genetic divergence, likely originating from an erratic recruitment process in the course of warming. Some of our evidence may be of relevance for inferring future arctic plant assembly rules and diversity changes. By analogy to the past, we expect a lagged response of tree invasion. Plant richness might overshoot in the short term; in the long-term, however, the ongoing expansion of deciduous shrubs will eventually result in a phylogenetically more diverse community.}, language = {en} } @article{DentonOfmanShpritsetal.2019, author = {Denton, Richard E. and Ofman, L. and Shprits, Yuri and Bortnik, J. and Millan, R. M. and Rodger, C. J. and da Silva, C. L. and Rogers, B. N. and Hudson, M. K. and Liu, K. and Min, K. and Glocer, A. and Komar, C.}, title = {Pitch Angle Scattering of Sub-MeV Relativistic Electrons by Electromagnetic Ion Cyclotron Waves}, series = {Journal of geophysical research : Space physics}, volume = {124}, journal = {Journal of geophysical research : Space physics}, number = {7}, publisher = {American Geophysical Union}, address = {Washington}, issn = {2169-9402}, doi = {10.1029/2018JA026384}, pages = {5610 -- 5626}, year = {2019}, abstract = {Electromagnetic ion cyclotron (EMIC) waves have long been considered to be a significant loss mechanism for relativistic electrons. This has most often been attributed to resonant interactions with the highest amplitude waves. But recent observations have suggested that the dominant energy of electrons precipitated to the atmosphere may often be relatively low, less than 1 MeV, whereas the minimum resonant energy of the highest amplitude waves is often greater than 2 MeV. Here we use relativistic electron test particle simulations in the wavefields of a hybrid code simulation of EMIC waves in dipole geometry in order to show that significant pitch angle scattering can occur due to interaction with low-amplitude short-wavelength EMIC waves. In the case we examined, these waves are in the H band (at frequencies above the He+ gyrofrequency), even though the highest amplitude waves were in the He band frequency range (below the He+ gyrofrequency). We also present wave power distributions for 29 EMIC simulations in straight magnetic field line geometry that show that the high wave number portion of the spectrum is in every case mostly due to the H band waves. Though He band waves are often associated with relativistic electron precipitation, it is possible that the He band waves do not directly scatter the sub-megaelectron volts (sub-MeV) electrons, but that the presence of He band waves is associated with high plasma density which lowers the minimum resonant energy so that these electrons can more easily resonate with the H band waves.}, language = {en} } @techreport{BrodeurMikolaCooketal.2024, type = {Working Paper}, author = {Brodeur, Abel and Mikola, Derek and Cook, Nikolai and Brailey, Thomas and Briggs, Ryan and Gendre, Alexandra de and Dupraz, Yannick and Fiala, Lenka and Gabani, Jacopo and Gauriot, Romain and Haddad, Joanne and Lima, Goncalo and Ankel-Peters, J{\"o}rg and Dreber, Anna and Campbell, Douglas and Kattan, Lamis and Fages, Diego Marino and Mierisch, Fabian and Sun, Pu and Wright, Taylor and Connolly, Marie and Hoces de la Guardia, Fernando and Johannesson, Magnus and Miguel, Edward and Vilhuber, Lars and Abarca, Alejandro and Acharya, Mahesh and Adjisse, Sossou Simplice and Akhtar, Ahwaz and Lizardi, Eduardo Alberto Ramirez and Albrecht, Sabina and Andersen, Synve Nygaard and Andlib, Zubaria and Arrora, Falak and Ash, Thomas and Bacher, Etienne and Bachler, Sebastian and Bacon, F{\´e}lix and Bagues, Manuel and Balogh, Timea and Batmanov, Alisher and Barschkett, Mara and Basdil, B. Kaan and Dower, Jaromneda and Castek, Ondrej and Caviglia-Harris, Jill and Strand, Gabriella Chauca and Chen, Shi and Chzhen, Asya and Chung, Jong and Collins, Jason and Coppock, Alexander and Cordeau, Hugo and Couillard, Ben and Crechet, Jonathan and Crippa, Lorenzo and Cui, Jeanne and Czymara, Christian and Daarstad, Haley and Dao, Danh Chi and Dao, Dong and Schmandt, Marco David and Linde, Astrid de and Melo, Lucas De and Deer, Lachlan and Vera, Micole De and Dimitrova, Velichka and Dollbaum, Jan Fabian and Dollbaum, Jan Matti and Donnelly, Michael and Huynh, Luu Duc Toan and Dumbalska, Tsvetomira and Duncan, Jamie and Duong, Kiet Tuan and Duprey, Thibaut and Dworschak, Christoph and Ellingsrud, Sigmund and Elminejad, Ali and Eissa, Yasmine and Erhart, Andrea and Etingin-Frati, Giulian and Fatemi-Pour, Elaheh and Federice, Alexa and Feld, Jan and Fenig, Guidon and Firouzjaeiangalougah, Mojtaba and Fleisje, Erlend and Fortier-Chouinard, Alexandre and Engel, Julia Francesca and Fries, Tilman and Fortier, Reid and Fr{\´e}chet, Nadjim and Galipeau, Thomas and Gallegos, Sebasti{\´a}n and Gangji, Areez and Gao, Xiaoying and Garnache, Clo{\´e} and G{\´a}sp{\´a}r, Attila and Gavrilova, Evelina and Ghosh, Arijit and Gibney, Garreth and Gibson, Grant and Godager, Geir and Goff, Leonard and Gong, Da and Gonz{\´a}lez, Javier and Gretton, Jeremy and Griffa, Cristina and Grigoryeva, Idaliya and Grtting, Maja and Guntermann, Eric and Guo, Jiaqi and Gugushvili, Alexi and Habibnia, Hooman and H{\"a}ffner, Sonja and Hall, Jonathan D. and Hammar, Olle and Kordt, Amund Hanson and Hashimoto, Barry and Hartley, Jonathan S. and Hausladen, Carina I. and Havr{\´a}nek, Tom{\´a}š and Hazen, Jacob and He, Harry and Hepplewhite, Matthew and Herrera-Rodriguez, Mario and Heuer, Felix and Heyes, Anthony and Ho, Anson T. Y. and Holmes, Jonathan and Holzknecht, Armando and Hsu, Yu-Hsiang Dexter and Hu, Shiang-Hung and Huang, Yu-Shiuan and Huebener, Mathias and Huber, Christoph and Huynh, Kim P. and Irsova, Zuzana and Isler, Ozan and Jakobsson, Niklas and Frith, Michael James and Jananji, Rapha{\"e}l and Jayalath, Tharaka A. and Jetter, Michael and John, Jenny and Forshaw, Rachel Joy and Juan, Felipe and Kadriu, Valon and Karim, Sunny and Kelly, Edmund and Dang, Duy Khanh Hoang and Khushboo, Tazia and Kim, Jin and Kjellsson, Gustav and Kjelsrud, Anders and Kotsadam, Andreas and Korpershoek, Jori and Krashinsky, Lewis and Kundu, Suranjana and Kustov, Alexander and Lalayev, Nurlan and Langlois, Audr{\´e}e and Laufer, Jill and Lee-Whiting, Blake and Leibing, Andreas and Lenz, Gabriel and Levin, Joel and Li, Peng and Li, Tongzhe and Lin, Yuchen and Listo, Ariel and Liu, Dan and Lu, Xuewen and Lukmanova, Elvina and Luscombe, Alex and Lusher, Lester R. and Lyu, Ke and Ma, Hai and M{\"a}der, Nicolas and Makate, Clifton and Malmberg, Alice and Maitra, Adit and Mandas, Marco and Marcus, Jan and Margaryan, Shushanik and M{\´a}rk, Lili and Martignano, Andres and Marsh, Abigail and Masetto, Isabella and McCanny, Anthony and McManus, Emma and McWay, Ryan and Metson, Lennard and Kinge, Jonas Minet and Mishra, Sumit and Mohnen, Myra and M{\"o}ller, Jakob and Montambeault, Rosalie and Montpetit, S{\´e}bastien and Morin, Louis-Philippe and Morris, Todd and Moser, Scott and Motoki, Fabio and Muehlenbachs, Lucija and Musulan, Andreea and Musumeci, Marco and Nabin, Munirul and Nchare, Karim and Neubauer, Florian and Nguyen, Quan M. P. and Nguyen, Tuan and Nguyen-Tien, Viet and Niazi, Ali and Nikolaishvili, Giorgi and Nordstrom, Ardyn and N{\"u}, Patrick and Odermatt, Angela and Olson, Matt and ien, Henning and {\"O}lkers, Tim and Vert, Miquel Oliver i. and Oral, Emre and Oswald, Christian and Ousman, Ali and {\"O}zak, {\"O}mer and Pandey, Shubham and Pavlov, Alexandre and Pelli, Martino and Penheiro, Romeo and Park, RyuGyung and Martel, Eva P{\´e}rez and Petrovičov{\´a}, Tereza and Phan, Linh and Prettyman, Alexa and Proch{\´a}zka, Jakub and Putri, Aqila and Quandt, Julian and Qiu, Kangyu and Nguyen, Loan Quynh Thi and Rahman, Andaleeb and Rea, Carson H. and Reiremo, Adam and Ren{\´e}e, La{\"e}titia and Richardson, Joseph and Rivers, Nicholas and Rodrigues, Bruno and Roelofs, William and Roemer, Tobias and Rogeberg, Ole and Rose, Julian and Roskos-Ewoldsen, Andrew and Rosmer, Paul and Sabada, Barbara and Saberian, Soodeh and Salamanca, Nicolas and Sator, Georg and Sawyer, Antoine and Scates, Daniel and Schl{\"u}ter, Elmar and Sells, Cameron and Sen, Sharmi and Sethi, Ritika and Shcherbiak, Anna and Sogaolu, Moyosore and Soosalu, Matt and Srensen, Erik and Sovani, Manali and Spencer, Noah and Staubli, Stefan and Stans, Renske and Stewart, Anya and Stips, Felix and Stockley, Kieran and Strobel, Stephenson and Struby, Ethan and Tang, John and Tanrisever, Idil and Yang, Thomas Tao and Tastan, Ipek and Tatić, Dejan and Tatlow, Benjamin and Seuyong, F{\´e}raud Tchuisseu and Th{\´e}riault, R{\´e}mi and Thivierge, Vincent and Tian, Wenjie and Toma, Filip-Mihai and Totarelli, Maddalena and Tran, Van-Anh and Truong, Hung and Tsoy, Nikita and Tuzcuoglu, Kerem and Ubfal, Diego and Villalobos, Laura and Walterskirchen, Julian and Wang, Joseph Taoyi and Wattal, Vasudha and Webb, Matthew D. and Weber, Bryan and Weisser, Reinhard and Weng, Wei-Chien and Westheide, Christian and White, Kimberly and Winter, Jacob and Wochner, Timo and Woerman, Matt and Wong, Jared and Woodard, Ritchie and Wroński, Marcin and Yazbeck, Myra and Yang, Gustav Chung and Yap, Luther and Yassin, Kareman and Ye, Hao and Yoon, Jin Young and Yurris, Chris and Zahra, Tahreen and Zaneva, Mirela and Zayat, Aline and Zhang, Jonathan and Zhao, Ziwei and Yaolang, Zhong}, title = {Mass reproducibility and replicability}, series = {I4R discussion paper series}, journal = {I4R discussion paper series}, number = {107}, publisher = {Institute for Replication}, address = {Essen}, issn = {2752-1931}, pages = {250}, year = {2024}, abstract = {This study pushes our understanding of research reliability by reproducing and replicating claims from 110 papers in leading economic and political science journals. The analysis involves computational reproducibility checks and robustness assessments. It reveals several patterns. First, we uncover a high rate of fully computationally reproducible results (over 85\%). Second, excluding minor issues like missing packages or broken pathways, we uncover coding errors for about 25\% of studies, with some studies containing multiple errors. Third, we test the robustness of the results to 5,511 re-analyses. We find a robustness reproducibility of about 70\%. Robustness reproducibility rates are relatively higher for re-analyses that introduce new data and lower for re-analyses that change the sample or the definition of the dependent variable. Fourth, 52\% of re-analysis effect size estimates are smaller than the original published estimates and the average statistical significance of a re-analysis is 77\% of the original. Lastly, we rely on six teams of researchers working independently to answer eight additional research questions on the determinants of robustness reproducibility. Most teams find a negative relationship between replicators' experience and reproducibility, while finding no relationship between reproducibility and the provision of intermediate or even raw data combined with the necessary cleaning codes.}, language = {en} }