Institution
University of Fribourg
Education•Fribourg, Freiburg, Switzerland•
About: University of Fribourg is a education organization based out in Fribourg, Freiburg, Switzerland. It is known for research contribution in the topics: Population & Context (language use). The organization has 6040 authors who have published 14975 publications receiving 542500 citations. The organization is also known as: UNIFR & Universität Freiburg.
Papers published on a yearly basis
Papers
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TL;DR: It is found that exposing PSCs to a temperature of 70 °C is enough to induce gold migration through the hole-transporting layer (HTL), spiro-MeOTAD, and into the perovskite material, which in turn severely affects the device performance metrics under working conditions.
Abstract: Perovskite solar cells (PSCs) have now achieved efficiencies in excess of 22%, but very little is known about their long-term stability under thermal stress. So far, stability reports have hinted at the importance of substituting the organic components, but little attention has been given to the metal contact. We investigated the stability of state-of-the-art PSCs with efficiencies exceeding 20%. Remarkably, we found that exposing PSCs to a temperature of 70 °C is enough to induce gold migration through the hole-transporting layer (HTL), spiro-MeOTAD, and into the perovskite material, which in turn severely affects the device performance metrics under working conditions. Importantly, we found that the main cause of irreversible degradation is not due to decomposition of the organic and hybrid perovskite layers. By introducing a Cr metal interlayer between the HTL and gold electrode, high-temperature-induced irreversible long-term losses are avoided. This key finding is essential in the quest for achieving...
914 citations
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Alfred Wegener Institute for Polar and Marine Research1, Geological Survey of Canada2, University of Lisbon3, George Washington University4, University of Alaska Fairbanks5, University of Ottawa6, Laval University7, Humboldt State University8, University of Fribourg9, University of Potsdam10, University of Oslo11, Technical University of Denmark12, Norwegian Meteorological Institute13, Hokkaido University14, Lund University15, Free University of Berlin16, University of Lausanne17, Rhodes University18, University of Barcelona19, University of Alcalá20, Stockholm University21
TL;DR: Climate change strongly impacts regions in high latitudes and altitudes that store high amounts of carbon in yet frozen ground, and the authors show that the consequence of these changes is global warming of permafrost at depths greater than 10 m in the Northern Hemisphere, in mountains, and in Antarctica.
Abstract: Permafrost warming has the potential to amplify global climate change, because when frozen sediments thaw it unlocks soil organic carbon. Yet to date, no globally consistent assessment of permafrost temperature change has been compiled. Here we use a global data set of permafrost temperature time series from the Global Terrestrial Network for Permafrost to evaluate temperature change across permafrost regions for the period since the International Polar Year (2007–2009). During the reference decade between 2007 and 2016, ground temperature near the depth of zero annual amplitude in the continuous permafrost zone increased by 0.39 ± 0.15 °C. Over the same period, discontinuous permafrost warmed by 0.20 ± 0.10 °C. Permafrost in mountains warmed by 0.19 ± 0.05 °C and in Antarctica by 0.37 ± 0.10 °C. Globally, permafrost temperature increased by 0.29 ± 0.12 °C. The observed trend follows the Arctic amplification of air temperature increase in the Northern Hemisphere. In the discontinuous zone, however, ground warming occurred due to increased snow thickness while air temperature remained statistically unchanged.
906 citations
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TL;DR: This review surveys the organization of the olfactory and gustatory systems in the imago and in the larva of Drosophila melanogaster, both at the sensory and the central level.
Abstract: This review surveys the organization of the olfactory and gustatory systems in the imago and in the larva of Drosophila melanogaster, both at the sensory and the central level. Olfactory epithelia of the adult are located primarily on the third antennal segment (funiculus) and on the maxillary palps. About 200 basiconic (BS), 150 trichoid (TS) and 60 coeloconic sensilla (CS) cover the surface of the funiculus, and an additional 60 BS are located on the maxillary palps. Males possess about 30% more TS but 20% fewer BS than females. All these sensilla are multineuronal; they may be purely olfactory or multimodal with an olfactory component. Antennal and maxillary afferents converge onto approximately 35 glomeruli within the antennal lobe. These projections obey precise rules: individual fibers are glomerulus-specific, and different types of sensilla are associated with particular subsets of glomeruli. Possible functions of antennal glomeruli are discussed. In contrast to olfactory sensilla, gustatory sensilla of the imago are located at many sites, including the labellum, the pharynx, the legs, the wing margin and the female genitalia. Each of these sensory sites has its own central target. Taste sensilla are usually composed of one mechano-and three chemosensory neurons. Individual chemosensory neurons within a sensillum respond to distinct subsets of molecules and project into different central target regions. The chemosensory system of the larva is much simpler and consists essentially of three major sensillar complexes on the cephalic lobe, the dorsal, terminal and ventral organs, and a series of pharyngeal sensilla.
900 citations
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TL;DR: Simulations on four real networks show that the proposed semi-local centrality measure can well identify influential nodes and is a tradeoff between the low-relevant degree centrality and other time-consuming measures.
Abstract: Identifying influential nodes that lead to faster and wider spreading in complex networks is of theoretical and practical significance. The degree centrality method is very simple but of little relevance. Global metrics such as betweenness centrality and closeness centrality can better identify influential nodes, but are incapable to be applied in large-scale networks due to the computational complexity. In order to design an effective ranking method, we proposed a semi-local centrality measure as a tradeoff between the low-relevant degree centrality and other time-consuming measures. We use the Susceptible–Infected–Recovered (SIR) model to evaluate the performance by using the spreading rate and the number of infected nodes. Simulations on four real networks show that our method can well identify influential nodes.
898 citations
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TL;DR: This paper introduces a new algorithm specifically to address the challenge of diversity and shows how it can be used to resolve this apparent dilemma when combined in an elegant hybrid with an accuracy-focused algorithm.
Abstract: Recommender systems use data on past user preferences to predict possible future likes and interests. A key challenge is that while the most useful individual recommendations are to be found among diverse niche objects, the most reliably accurate results are obtained by methods that recommend objects based on user or object similarity. In this paper we introduce a new algorithm specifically to address the challenge of diversity and show how it can be used to resolve this apparent dilemma when combined in an elegant hybrid with an accuracy-focused algorithm. By tuning the hybrid appropriately we are able to obtain, without relying on any semantic or context-specific information, simultaneous gains in both accuracy and diversity of recommendations.
891 citations
Authors
Showing all 6204 results
Name | H-index | Papers | Citations |
---|---|---|---|
Jens Nielsen | 149 | 1752 | 104005 |
Sw. Banerjee | 146 | 1906 | 124364 |
Hans Peter Beck | 143 | 1134 | 91858 |
Patrice Nordmann | 127 | 790 | 67031 |
Abraham Z. Snyder | 125 | 329 | 91997 |
Csaba Szabó | 123 | 958 | 61791 |
Robert Edwards | 121 | 775 | 74552 |
Laurent Poirel | 117 | 621 | 53680 |
Thomas Münzel | 116 | 1055 | 57716 |
David G. Amaral | 112 | 302 | 49094 |
F. Blanc | 107 | 1514 | 58418 |
Markus Stoffel | 102 | 620 | 50796 |
Vincenzo Balzani | 101 | 476 | 45722 |
Enrico Bertini | 99 | 865 | 38167 |
Sandeep Kumar | 94 | 1563 | 38652 |