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Mathematisch-naturwissenschaftliche Fakultät


  • Women in Science Kampagne 2023

    Wir stellen von Februar bis Juni 2023 jeweils eine unserer aktuellen Professorinnen und eine internationale Pionierin des Forschungsgebiets vor – denn Frauen in der Wissenschaft müssen gesehen werden. Mit dieser Initiative und ihrem vielfältigen Begleitprogramm wollen wir ALLEN die Wissenschaft näherbringen und insbesondere die nächste Generation inspirieren.

    Die Women in Science Kampagne der MNF mit Prof. Meredith (Merry) Christine Schuman - Prof. Corinna Ulcigrai  - Prof. Alexandria (Ali) Liang - Prof. Ravit Helled - Prof. Catalina Pimiento Hernandez.

    Korinna Esfeld, Dr.
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    2023-02-27, News
  • Weniger Fake News, aber zunehmende Polarisierung auf Twitter

    Social media has been transforming political communication dynamics for over a decade. Any social media user has the potential to directly reach millions of users, in a few minutes, and influence political campaigns. Such control over political discussions used to be the privilege of just a few persons, principally journalists. On social media, they now have to compete directly with politicians, users spreading fake news, and members of the public for our attention. To better understand the role of these new dynamics in politics, together with an international team of researchers, Alexandre Bovet, Assistant Professor in Quantitative Network Science at the Department of Mathematics and the Digital Society Initiative, analyzed nearly a billion tweets sent during the 2016 and 2020 US presidential elections.

    The team measured the volume of politically biased content and the number of users propagating such information. By reconstructing the networks of news diffusion they were able to identify news influencers, i.e. the users with the greatest ability to spread news in the Twitter network. Collecting data from two subsequent elections enabled the team to see trends in participation, polarization, and stability of different kinds of influencers. In a broader sense, it revealed the role that the social media platform played in the elections.

    On the positive side, they measured a decrease in the number of tweets and users propagating fake and extremely biased news in 2020 compared to 2016, probably due to the measures put in place by Twitter to tackle such content. But they also revealed an increase in polarization, at the level of the top influencers and of the average users, in 2020, i.e. users were less likely to share information from other users with opposite political ideologies. This indicates increasing echo chambers for users with a lack of contrary views.

    They also observed interesting changes in the top news influencers. Between 2016 and 2020, for influencers with center and right-leaning political ideologies, the number of influencers affiliated with media organizations (journalists and accounts belonging to news outlets) declined by 10%, replaced mostly by politicians. On the other hand, influencers spreading fake news, who were largely comprised of users not affiliated with political or media organizations in 2016, have been replaced in good part by new users affiliated with media organizations that emerged between 2016 and 2020. This change in the news media landscape on Twitter indicates a shift in the relative influence of journalists and political organizations as well as a professionalization of the disinformation industry.

    This research reveals the quickly changing dynamics of social media platforms. It also asks the question of how platforms should be designed and regulated in order to control the increase of polarization and echo chambers.

    Alexandre Bovet was joined in the research by Boleslaw Szymanski, James Flamino, and Brendan Cross from the Rensselaer Polytechnic Institute, Alessandro Galeazzi of the University of Brescia and Ca’ Foscari University of Venice, Stuart Feldman of Schmidt Futures, Michael W. Macy of Cornell University, Zhenkun Zhou of the Capital University of Economics and Business in Beijing, Hernán A. Makse and Matteo Serafino of the City College of New York.


    Top, the latent ideology of the top five influencers of each category is shown as a box plot representing the distribution of the ideology of the users who retweeted them. Bottom, the distributions for the users are shown in green and the distributions for the top 100 influencers of each news media category (computed as the median of the ideology of their retweeters) are displayed in purple. Box plots indicate the median and the 25th and 75th percentiles of the distributions with whiskers indicating the 5th and 95th percentiles. The sample size used for the computation of each box plot is reported to their side. Pie charts next to the influencers’ names represent the news categories to which they belong (weighted by their respective CI ranks in each category). (link to figure:

    Alexandre Bovet
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    2023-04-28, Sci. Publication
  • Arthropoden in artenreichen Wäldern verbessern die Produktivität

    An international team of Chinese, German and Swiss researchers has shown that forests with higher tree species richness tend to have a greater diversity of arthropods. In addition, the study shows that higher tree diversity promotes productivity, due to the suppression of herbivores by enemy arthropods. The results have recently been published in the journal Nature Ecology & Evolution. These findings underscore the importance of arthropod diversity as a mediator of tree diversity effects on forest productivity. The work suggests that managing forests for increased productivity will require both increased tree diversity and multitrophic diversity.

    Forests are home to 80% of terrestrial plant and animal diversity, making them a crucial component of global biodiversity conservation. However, biodiversity in forests is under serious threat from anthropogenic disturbance and climate change. Species-rich groups, such as arthropods, are declining dramatically due to the degradation of forests and loss of plant diversity. Most studies on biodiversity–ecosystem functioning (BEF) relationships have focused solely on plant diversity, neglecting the impact of the diversity of other trophic groups. In consequence, it remains unclear how the diversity of herbivores and their enemies affects ecosystem functions. Given the importance of forests to providing essential ecosystem services and global biodiversity, it is vital to understand these interconnections and take action to protect them.

                Using five years of data on aboveground herbivorous, predatory, and parasitoid arthropods along with tree growth data within a large-scale forest biodiversity experiment in southeast China (BEF-China), the authors reveal that the effects of increased tree species richness were consistently positive for species richness and abundance of herbivores, predators, and parasitoids. This finding is consistent with a previous study from another large grassland biodiversity experiment (Jena Experiment) and reinforces the importance of conserving plant diversity for preserving arthropod diversity.

    However, in contrast to the bottom-up control of arthropod diversity by plant diversity in the grassland study from central Europe, the new study in the species-rich forests of south-east China reveals that higher tree diversity can enhance the top-down control of enemies over herbivores, thereby contributing to increased productivity. An earlier study conducted at the same sites demonstrated that increasing plant diversity can promote forest productivity directly. The new study further shows that increasing plant diversity can also indirectly increase forest productivity by promoting arthropod diversity and trophic interactions. Prof. Xiaojuan Liu, a former postdoc at UZH and last author of the study, says, “this underscores the critical role of conservation efforts aimed at preserving biodiversity in forests.”

    Overall, although several recent studies have documented declines in terrestrial arthropod biodiversity, few have explored the consequences for ecosystems. “This work closes this gap by revealing the important role of arthropod diversity in BEF relationships”, says Prof. Bernhard Schmid, one of the senior authors of the study.


    Article: Yi Li, Bernhard Schmid, Andreas Schuldt, Shan Li, Ming-Qiang Wang, Felix Fornoff, Michael Staab, Peng-Fei Guo, Perttu Anttonen, Douglas Chesters, Helge Bruelheide, Chao-Dong Zhu, Keping Ma, Xiaojuan Liu. Multitrophic arthropod diversity mediates tree diversity effects on primary productivity. Nature Ecology & Evolution. 2023.

    Article link:



    Bernhard Schmid
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    2023-05-04, Sci. Publication
  • 1 Million von der Werner Siemens-Stiftung für Projektidee

    Greta Patzke und David Tilley gehören mit ihrem Projekt zur Entwicklung von grünem Wasserstoff zu den sechs Projektgruppen die von der Werner Siemens-Stiftung (WSS) 1 Million Franken für ihre Forschung erhalten. Die WWS hatte zu ihren 100-jährigen Bestehen einen Ideenwettbewerb für ein WSS-Forschungszentrum «Technologien für eine nachhaltige Ressourcennutzung» ausgeschrieben. Damit fördern sie ein WSS-Forschungszentrum, das Technologien für eine nachhaltige Ressourcennutzung erforschen und entwickeln wird. Ausgestattet wird das Zentrum mit gesamthaft 100 Millionen Schweizer Franken für einen Förderzeitraum von zehn Jahren. Dieser Entscheid wird im Dezember 2023 fallen.

    Email Author

    2023-05-04, Awards and Honors
  • Ehrendoktorwürde für Maude Barlow

    Im Rahmen des Dies Academicus der UZH am 29. April 2023 bekam Maude Barlow die Ehrendoktorwürde der Mathematisch-naturwissenschaftlichen Fakultät verliehen. Die Fakultät würdigt damit die Anstrengungen von Maude Barlow für die Anerkennung des grundlegenden Menschenrechts auf Wasser. Zudem ist sie Gründungsmitglied der «Blue Community», der die UZH im Mai 2022 beigetreten ist.

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    2023-05-25, Event
  • Integrating Diverse Forms of Knowledge in Health Care Research

    Dr. Chloe Pasin, fellow at the Collegium Helveticum, is organising a workshop on Tuesday June 20: Integrating Diverse Forms of Knowledge in Health Care Research. 

    How can interdisciplinary studies in health help bridge between the biomedical field and other academic fields as well as non-academic settings to expand our global understanding of health and address health inequalities? This is the main question, which this workshop wants to discuss. Structured around two panels, the workshop seeks to bring experts from various fields into dialog with each other.

    Chloé Pasin
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    Collegium Helveticum


    2023-06-02, Event
  • 3-2-1 Go Euclid!

    The UZH Space Hub, in collaboration with the Euclid members at Institute for Computational Science , will be organizing a special Space Cafe event dedicated to Euclid next month. Euclid is an ESA mission designed to map the large-scale structure of the Universe with unprecedented accuracy. It aims to tackle the most pressing open questions in Cosmology, including the nature of dark matter and dark energy.

    As the launch of Euclid is scheduled for the first half of July, we would like to take this opportunity to share with you the objectives of the Euclid mission and what we expect to discover over the next decade. Moreover, this event will serve as a celebration of the imminent launch, and we would be delighted to have you join us.

    The event will take place on June 16th at the Irchel Campus, starting at 2:30 pm. It will feature short presentations from the Euclid members, followed by an Apero commencing at approximately 4:30 pm. To view the full program, please visit the following link:

    We kindly request that you register via the webpage, as it will assist us in planning the catering. However, spontaneous participation is also welcomed.

    We hope to see many of you there, as your presence will make the event even more enjoyable.

    Francesca Lepori
    Email Author


    2023-06-07, Event