Linnaeus University Centre for Intermedial and Multimodal Studies (IMS)

Understanding an evolving world of human communication through multimodality and intermediality

The Linnaeus University Centre for Intermedial and Multimodal Studies (IMS) is an internationally known Centre of Excellence dedicated to intermediality, multimodality, and media research. It is an active environment bringing together doctoral candidates and researchers from a wide range of disciplines. The Centre sustains a vibrant seminar series, often featuring leading scholars.

IMS collaborates within the Linnaeus Media Observatory (LiMO).

Why research on Intermediality and Multimodality matters

We are encountering new ways of combining texts, images and sounds, which we send and share in ways previously unimaginable. The boundaries between proximity and distance, original and copy, human and machine, private and public are now more fluid and complex.

The development is changing the way we learn, work, socialize, communicate and create knowledge. Intermediality and multimodality are both flexible and nuanced tools that help us understand the mix of resources and media in all forms of communication.

The centre's interdisciplinary approach brings together the fields of intermediality, multimodality, and media research, making the research at the Center unique and important in a rapidly evolving world.

Current Activities

23 September 2026
3:00 PM6:30 PM
Film Cultures of Protest: 1968 and Beyond

All Lnu-employees as well as Lnu Master students are welcome to join the IMS-seminars.

See previous activities

Research Visit Programme

Do you focus on topics related to intermediality and multimodality in the humanities and social sciences?

IMS invites scholars from all over the world at all career levels, from PhD candidates to full professors. You can visit the Centre for a period of between two weeks until three months.

If you are accepted to the programme, we expect you to participate in the Centre's activities and research groups. This includes presenting at seminars and taking part in workshops and other events.

Application

It’s preferable if you are sponsored by a member of the Centre. If so, the member can submit your application anytime during the year, and it usually takes about two months to process. If no direct collaboration is possible, but the visit would still be valuable (e.g., for PhD students), you can contact the Director, Jørgen Bruhn or Helena Rydén, the Centre's Administration Officer.

The visiting positions are unpaid. Visitors must have a salary or grant from their home institution. The Centre offers office space and access to its research activities, as well as university library services. In some cases, the Centre can provide basic accommodation and cover travel and extra living costs.

Marie Skłodowska-Curie Actions Individual Fellowships (MSCA-IF)

You can visit us with a Marie Skłodowska-Curie Actions Individual Fellowships (MSCA-IF). You are welcome to submit a proposal for participating in a workshop. The call for proposals opens approximately six months prior to the MSCA-IF deadline.

The workshop and ensuing contacts with our Grants and Innovation Office (GIO) should lead to an application for funding from MSCA-IF, allowing you to fulfil a research project and participate in activities at the Centre.

Residency Programmes

IMS is the academic host of the HULT residency in Kronoberg. Residens - Konst i Kronoberg. The residency provides curators and artists with the opportunity to explore the relationship between humans and to connect art, climate change and community development.

[Hillside Projects | Office for Continuing Research on Birds] Fågelskådning på liv och död - Konst Sydost

IMS also take part in the Linnaeus Residency Programme.

Lars Elleström Memorial Fellowship

Every year the Centre invites a guest lecturer to honor the memory its founder, Lars Elleström. The guest lecturers aim to foster new research in intermedial and multimodal studies, illustrating how one can both follow in Elleström’s footsteps and challenge his principles.

Interested? Please contact the Director, Jørgen Bruhn or Helena Rydén, the Centre's Administration Officer.

Professor Lars Elleström

Lars Elleström (1960–2021) was a Professor of Comparative Literature at Linnaeus University, Sweden. He founded the Linnaeus University’s Centre for Intermedial and Multimodal Studies (IMS) in 2014, and was leader of the Centre until he passed away. Elleström’s medial framework on media types and media modalities significantly influences much of the ongoing research.

The critical legacy of Elleström
The study of media interrelations is a critical area of research that explores how different forms of media – ranging from personal bodies and their extensions to written texts and films – interact in ways that profoundly impact the production and transfer of meaning. By refining the theoretical frameworks needed to analyze these interrelations, IMS researchers aim to address gaps in earlier models.

Stay updated on Facebook and YouTube.

Shortcuts

• Publications • Researchers • Education

Research Clusters

The transdisciplinary research clusters explore how intermedial and multimodal communication shapes current social challenges.

Research projects

Written about IMS

View all news

Publications

Publications available in DiVA

Researchers

Staff

PhD Students

Guest Researchers and Postdocs

2025

Silvia Kurr (Visiting researcher)
Youngmin Kim (Visiting Professor)
Guo Rongrong (Visiting PhD)

2024

Luca Diani (Visiting PhD)
Alexandra Huang-Kokina (Visiting researcher)
Youngmin Kim (Vistiting Professor)

2023

Panagiotis Zestanakis (Marie Curie postdoc 2023-)
Yikun Wu (External postdoc)
Xiaoshang Shuiping (Guest researcher)
Heidi Hart (Guest researcher)
Youngmin Kim (Visiting Professor)

2022

Anne Gjelsvik (Lars Elleström Guest Researcher)
Gibran de Souza (Guest PhD)
Giulia Bigongiari (Guest PhD)
Maddalena Carfora (Guest PhD)

2021

Eleni Timplalexi (Guest Researcher 2021)

2020

Péter Makai (External postdoc 2018-2020)
Emma Tornborg (Associated researcher and postdoc 2015-2020)
Lea Wierød (External postdoc 2018-2020)

2019

Mieke Bal (Visiting Professor 2019)
Fátima Chinita (External postdoc 2015-2019)
Ania Gutowska (Marie Curie postdoc 2017-2019)
Rong Ou (External postdoc 2019)

2018

Ana Munari (External postdoc 2018)

Affiliated Researchers

Research Network

Within Linnaeus University

National

Within Europe

University of Edinburgh. Intermediality: Literature, Film and the Arts in Dialogue
University of Liège. CIPA - Centre Interdisciplinaire de Poétique Appliquée.
Literature Among Media, Aarhus University
Finnish Centre of Excellence in Research on Intersubjectivity in Interaction, University of Helsinki
Nordic Network for Literature and Mediality
Opera in Scandinavia, Sibelius Academy
Institut für Kirchenmusik und Musikwissenschaft, University of Greifswald
Musik und Gender, Hochschule für Theater, Musik und Medien, Hanover
Research Group in Media Studies, Jan-Noël Thon as Chair, University of Tübingen
Music and Media, International Musicological Society, Utrecht University
The RECODE Team, University of Sheffield
Metaphors in end-of-life care (MELC), Lancaster University
Research group in Intermediality, Agnes Pethö as Chair, Sapientia University
Research group in Film and Intermediality, Claudiu Turcus as Chair, Babes-Bolyai University
The Frankfurt Memory Studies Platform
Multimodalitätsforschung in Bremen - Universität Bremen (uni-bremen.de)
Journalistisches Seminar Mainz (uni-mainz.de)

Worldwide

Department for Music and Theatre Studies, Maseno University
National Institute of Education, Nanayang Technological University
Iconicity research group, Federal University of Juiz de Fora
Iconicity in Language and Literature
Inter-Disciplinary.Net
International Society for the Study of Self Injury
Screenwriting Research Network
Word and Music Association Forum

Expert Panel

IMS has arrangements with several external, internationally acknowledged scholars, referred to as our 'expert panel', working within a range of disciplines of relevance to the developing fields of intermediality and multimodality.

The individual members of the expert panel are for example called upon as advisors when new IMS-founding applications have to be developed, or as guest presenters at our IMS seminars, doctoral courses and internal colloquiums and research workshops.

Ágnes Pethö: Professor of Film Studies, Sapientia University
Anne Gjelsvik: Professor of Film Studies, Norwegian University of Science and Technology
Asbjørn Grønstad: Professor, Department of Information Science and Media Studies, University of Bergen
Bridgette Wessels: Professor in the Sociology of Inequalities (Sociology), University of Glasgow
Carey Jewitt: Professor of Learning and Technology, University College London
Chiel Kattenbelt: Associate Professor, Department of Media and Culture Studies, Universiteit Utrecht
Christina Ljungberg: Titularprofessorin für Englische und Amerikanische Literaturwissenschaft, University of Zurich
Claus Clüver: Professor Emeritus of Comparative Literature
Crispin Thurlow: Professor of Language and Communication, University of Bern
Eleni Timplalexi: National & Kapodistrian University of Athens
Irina Rajewsky: Professor of Comparative Literature, Johannes Gutenberg University Mainz
Jana Holšánová: Associate Professor in Cognitive Science, Lund University
Jens Schröter: Professor, Medienkulturwissenschaft, Lehrstuhl der Universität Bonn
João Queiroz: Professor, Institute of Arts and Design, Federal University of Juiz de Fora
John A. Bateman: Professor of Applied Linguistics at the University of Bremen
Kamilla Elliot: Professor of Literature and Media, Lancaster University
Katherine Hayles: James B. Duke Distinguished Professor Emerita of Literature, Duke Trinity College of Arts & Sciences
Kay O'Halloran: Chair Professor and Head of Department of Communication and Media, University of Liverpool
Klaus Bruhn Jensen: Professor, Department of Communication, University of Copenhagen
Marie-Laure Ryan: Literary scholar and critic
Masako Hiraga: Professor of Linguistics, Rikkyo University
Mieke Bal: Cultural theorist and critic, Video artist
Morten Kyndrup: Professor, School of Communication and Culture - Aesthetics and Culture, Aarhus University
Pentti Haddington: Professor of English Philology, University of Oulu
Siglind Bruhn: Musicologist
Sigrid Norris: Professor of Multimodal (Inter)action, Auckland University of Technology
Thomas Leitch: Professor of English, Unidel Andrew B. Kirkpatrick Chair in Writing, University of Delaware
W. J. T. Mitchell: Gaylord Donnelley Distinguished Service Professor, Department of English, Department of Art History, Department of Visual Arts, The University of Chicago
Werner Wolf: Professor, Chair of English and General Literature, University of Graz
Yvonne Spielmann: Professor, Institute of Professional Development

Education

PhD Studies and Graduate Schools

MIDWorld

IMS runs the interdisciplinary graduate school MIDWorld in collaboration with the Centre for Research in the Humanities and the research team in Multimodal Communication at Örebro University. The interdisciplinary graduate school MIDWorld provides emerging researchers in the Humanities theories and methods to critically analyse the mix of modes and media in our digital world.

MIDWorld PhD students from LNU and Örebro

FUDEM

IMS is collaborating with the research school The Future of Democracy: Cultural Analyses of Illiberal Populism in Times of Crises (FUDEM), a multi-disciplinary environment in which junior and senior researchers in cultural studies, ethnology, gender studies, and musicology are doing research on the variety of cultural forms in which illiberal populism reveals itself in times of crises. The researchers and PhD students are located at six Swedish universities: Linnæus University, Linköping University, Lund University, Södertörn University, University of Gothenburg and Uppsala University. FUDEM is financially supported by the Swedish Research Council.

Master programmes

Courses

Previous Activities

Concluded Research

Seminars etc

Conferences and Workshops

2025

Workshop: ICLA Colloquium 'Intermedial studies and New Materialisms'. May 21-23 May.
Conference: Annual Swedish Phonetics Conference, FONETIK 2025. May 21-23.
Workshop: Gaming Intermediality: New Methods for Studying Digital Games. May 19-21.
Collaboration: IMS with new HULT artists in residence, Sara Rossling and Hillside Projects. With Region Kronoberg. May 8.
Workshop (Ph D): Stronger Together: How Multimodality and Intermediality Can Support Each Other. May 8-9.

2024

Conference: Intermedial Networks: The Digital Present and Beyond. The 7th Conference of the International Society for Intermedial Studies. October 23-25.
Conference programme.
Workshop: Transmediating Authorship. Tove Jansson and Astrid Lindgren. June 12.
Workshop: Comics och lärande. May 16.
Concert: Digital transformations. A dynamic encounter between music, art and technology. March 12.

2023

Conference: Media and Emotional Mobilization, 12-13 October.
Conference programme.
Workshop: Comics literacy and learning. May 4.
Seminar and Concert: Living scores. Intermediality and artistic research. April 12.
Conference: Environmental Emergencies Across Media, March 16-18.
Conference programme.

2022

Open lecture Series: Meeting Media Minds – Critical Legacies of Lars Elleström. (publication Future Directions in Intermediality and Multimodality: Conversations Inspired by the Work of Lars Elleström, forth 2024).
Wonderland Escape Room. European Researcher’s Night, Sept 22.
Teaching Intermediality March 23.

2021

Conference: "Trust Me!" Truthfulness and Truth Claims across Media", 9-12 March, 2021.
- Conference programme
- Conference book of abstracts
Workshop: "Från bok till film: Utvandrarna och Aniara." (about screenwriting, screenplay development, and adaptations). https://lnu.se/mot-linneuniversitetet/aktuellt/kalender/2021/fran-bok-till-film-utvandrarna-och-aniarany-sida/

2019

Workshop: “Mediation, transmediation and truthfulness II”, 20 Nov, 2019.
Symposium: Performativity across Media, 3-4 October 2019
Conference: Sounds of Mass Media: Music in Journalism and Propaganda, 7-9 June 2019, Eleventh meeting of the International Musicological Society (IMS) Study Group Music and Media (MaM)
Workshop: “Mediation, transmediation and truthfulness I”, 30 Jan, 2019
Conference: Multispecies Storytelling in Intermedial Practices, 23-25 January 2019

2018

Workshop: Interrelations among different forms of human communication, 29-31 October 2018
Conference: Symbiotic Cinema, Confluences between film and other Media, 6-8 September 2018, 24th Sercia Conference
Workshop: “Transmedial Narration: Current Approaches” with Jan Noël Thon, 11 April, 2018.

2016

Conference: Transmediations! Communication across Media Borders13-15 October 2016

2013

Conference: Disturbing Adaptations, 26-27 September 2013, The 8thAnnual Conference of the Association of Adaptation Studies

2012

Symposium: New Positions in Adaptation Studies, 8 February 2012

2011

Conference: Transmedial Interaction: Western/non-Western Media Arts, 8-10 December 2011
Symposium: Eighth International Symposium on Iconicity in Language and Literature, 16-18 June 2011
Symposium: Adaptation and Media Transformations, 13–14 May 2011
Symposium: Narration as a Transmedial Phenomenon, 11–12 March 2011

2010

Symposium: Virtual Space and Time, 8-9 October 2010

Researcher Interviews

IMS Research and Society is a series of ultra-short interviews originally published on Facebook. The intention behind the series has been to provide a quick entry point into what we are doing in IMS and why we are doing it. Please note that not all interviews below are part of the original series.

The interviews are centred around three questions:

what the research is about
why the research is important
how it engages with challenges in society

Lars Elleström on Media Relations

1. My research is about media interrelations. People use different kinds of media (including one’s own body and its extensions and external things such as written texts and movies) and these media forms interact in various ways that deeply affect how information and meaning is produced and transferred. I try to elaborate concepts that are helpful for understanding all forms of media interrelations.

2. Human communication is at the centre of virtually all human endeavours. Thus, getting a grip of how meaning can be on the one hand boosted and one the other hand corrupted through shifts of media appears to be imperative. I try to improve those theoretical frameworks that we need for understanding and analysing media interrelations. To my mind, earlier models are largely biased towards verbal communication and not sufficiently fine-grained.

3. As media are central at all levels of society, from the personal to the public, and as new media forms are constantly developed, understanding media interrelations is of perennial significance. My research will not solve any acute problems, but it might contribute a little bit to the long-term endeavour to better understand and act upon the complexity of human communication

Liviu Lutas on transmediality and intermedial ecocriticism

1. My project is mainly about transmediality of certain devices, especially narrative ones. Transmediality is the possibility to appear in different media, such as literature, film, music, newspapers, news reports, didactic material, etc. One interesting aspect to study is how the different devices differ according to the medium they appear in.

A more specific part of this project has to do with the representation of environmental issues in different media. “Intermedial Ecocriticism” is the term we coined to describe this. One of the most interesting environmental issues to study from such a perspective is the Anthropocene, that is the alleged epoch in our planet’s life dating from the start of significant human impact on the Earth's geology and ecosystems.

2. The research I am conducting is important since it brings together topical research fields: narrative studies, intermediality and ecocriticism. It does so in a rigorous way since the theoretical framework of narrative studies and intermediality are very well established at our research centre. At the same time, this research is also meant to contribute to the development of the theoretical framework.

The innovative aspect lies exactly in this bringing together of the three research fields.

3. My research engages with challenges in society in different ways. The most obvious way is in relation with the study of the representation of environmental issues. Research on a rigorous theoretical ground is important in today’s discourse on these vital matters.

In a more general, and thus less obvious, way, my research can contribute to bringing a critical distance to our approach to different discourses. By applying concepts derived from well-established theoretical frameworks, the truthfulness and reliability of different discourses can be studied thoroughly.

Read more about Liviu Lutas here: https://lnu.se/en/staff/liviu.lutas/

You can find more information about the research project "Transmediating the Anthropocene" here: https://lnu.se/.../project-transmediating-the-anthropocene/

Makai Péter Kristóf on evolution as represented in popular media

1. What is your project about?

Makai: I research how a scientific theory, the theory of evolution by natural selection, is expressed in different media, from fiction to nonfiction books, computer and board games, or TV documentaries. At the heart of this inquiry is my desire to see how truthful statements are articulated in different media, what media can and cannot do to convey factual content, and what else is needed besides the accuracy of the facts in order to make the subject entertaining and commercially successful.

2. Why is it important to do this kind of research? How is your research innovative?

Makai: How knowledge transfer occurs is something that researchers in education, science studies and the public understanding of science have been investigating, but media studies seems to be lagging behind. I want to have a large panorama view of different artists’ and scientists’ strategies of making evolution understandable, entertaining and factually correct at the same time. Media studies can help us become more aware of how different cultural forms shape the things that can be said and shown about the world. I use the results of cognitive science, psychology and studies of narrative to make sense of how we communicate evolution.

3. How does your research engage with challenges in society?

Makai: As a global society, we should be on the same page about basic facts of life in order to make good decisions, which have far-reaching consequences. The scientific method provides our best source of knowledge about the world, but it has been under attack from various political, religious and economic stakeholders because truth produced by science can challenge one’s worldview. Unfortunately, human minds have developed not to see the world as it is, but to help us make quick, unconscious decisions. If we do not become aware of how media affects the expression of true and false ideas, and how they connect with our personal values and societal goals, people will be more easily led astray by other people who exploit our ancient psychological instincts for their own gain.

Find more information about the research project "The Greatest Story Ever Told: Evolution’s journey across mediascapes" here: https://lnu.se/.../project-evolutions-journey-across.../

Beate Schirrmacher and Corina Löwe on Representation of Trials in other Media

1. We analyse the representation of trials in literature, news media, and film. When you think about it, it is a very complex task to re-present a trial, the interaction in the courtroom, the conflicting stories all with strong truth claims, how can you sum up all this? Which parts of the trial are considered representative for the whole, and how can a single story convey the complexity of conflicting stories presented at court? Besides, you also have to explain to your audience how the legal system works.

2. What we can see is that the representation of a trial in other media not only tells a true crime story but also touches upon general questions of evaluation, credibility, and truth claims in media.

Narratologist research often focuses mostly on the differences between stories in court and stories in the legal system and news media. From an intermedial perspective, we can analyze how these very differences are transmediating central conflicts and explaining the importance of what happened at court.

3. Reading a court report or watching a film about a trial is not only about “whodunit”. The question “how do we know what is true?” is always present. We think this is one explanation for the current interest in true crime and courtroom stories because here it is possible to witness a process of truth production: how (legal) facts are created out of conflicting stories. We are confronted with conflicting stories with strong truth claims in our daily use of digital media as well, and we have to learn how to evaluate credibility. Representations of trials can mediate how truth and facts are not only there, but produced - truth claims and the evaluation of credibility are made more explicit. Thus, our results can provide important knowledge for media literacy in the digital age.

Read more about Beate Schirrmacher here: https://lnu.se/en/staff/beate.schirrmacher/

Read more about Corina Löwe here: https://lnu.se/en/staff/corina.lowe/

You can find more information about the research project "Representation of Trials in other Media" here: https://lnu.se/.../project-narrating-the-trial.../

Martin Knust on developing critical perspectives on the evolution of news media

1. What is your project about?

Knust: My research focuses on present changes in media and journalism. “News” is no longer a format that is bound exclusively to classical mass media like tv, radio and print but has become more difficult to grasp. News spread in new ways that have a backlash on its content. The mediality and intermediality of the new environment for news have created an ecosystem of technical tools – partly deriving from fictional genres like computer games or movies – and information channels in which the borders between the traditional mass media become blurred and new media types emerge. Today, the presentation of news employs texts, (moving) pictures and most often also music. The latter has been ignored virtually completely in media research.

2. Why is it important to do this kind of research? How is your research innovative?

Knust: It is analyzing the design of news content from a historical and a critical perspective, showing the cultural mechanisms of how we perceive news, narratives and audio-visual media, raising awareness for the impact of form on media content. Given the intermedial character of my object it is interdisciplinary.

3. How does your research engage with challenges in society?

Knust: It does engage with it by posing these questions:

Short term: How does this design look like and what effects might it have on the spectator/listener? Which recent changes of politics have been triggered by the new media landscape? How are conflicts and crises described in media now compared to the pre-Internet era?

Long term: How does music work in non-fictional contexts? What are legitimate tools of journalism and what has to be considered manipulative in the context of the new media ecosystem?

....

You can read more about Martin Knust here: https://lnu.se/en/staff/martin.knust/

Find more information about the research project "Information, Desinformation and Media System Change": https://lnu.se/.../project-information-desinformation.../

Signe Kjær Jensen on animated films, music, and on listening to children's own voices when researching children's media

1. What is your project about?

In my PhD project, I focus on music in animated films for children. More specifically, I work with Frozen, Shrek the Third, and Up, and study how the music is used in these films in relation to the portrayal of characters. I then compare these insights to the way that children themselves (Danish children aged 7-11) talk about the music and their interpretations, to try and get a better understanding of how children make meaning from this complex medium.

2. Why is it important to do this kind of research? How is your research innovative?

I think it is really important to know more about how children themselves understand and interpret different stories and meaning carrying elements in the media, including music. We know from numerous research that music in films affects our interpretations, and some research even suggests that music can be used to manipulate audiences, but very little research has been focused on this intersection between children’s own descriptions, music, and animation films, despite music in animated films being such a large part of children's media culture.

3. How does your research engage with challenges in society?

Children are of course the future of our society, and stories in media aimed at children are a large part of their upbringing. I don’t think media are good or evil, or that we can create a simple formula for how media affect people, but given the widespread distribution and importance to many children's lives, I think it is important that we keep learning about and discussing children’s media. I also think it is important that we remember that children see and hear things in a story that we as adults don't, and that the 'content' of children's general media literacy is everchanging, but always different from that of the adult researcher. Stories are very rarely simply 'there' as objective unambiguous content, but are always to some degree 'flexible' and open to different interpretations dependent on the audience's interests, knowledge and experience. Children are, in my experience, very active and critical audiences, and we have to remember to talk to them, regularly, and to take their own words seriously when we research things like this that concern them.

....

You can read more about Signe Kjaer Jensen here: https://lnu.se/en/staff/signe.kjaerjensen/

Open Lecture Series: Meeting Media Minds – Critical Legacies of Lars Elleström

Following Lars Elleström's death in December 2021, we launched a series of online lectures with international scholars to commemorate his work. The invited speakers were asked to talk about and discuss one of Lars Elleström’s concepts in relation to their own work. The lectures will be published in an anthology in due time.

Linnaeus University Centre for Intermedial and Multimodal Studies (IMS)

Why research on Intermediality and Multimodality matters

Current Activities

Research Visit Programme

Application

Marie Skłodowska-Curie Actions Individual Fellowships (MSCA-IF)

Residency Programmes

Lars Elleström Memorial Fellowship

Shortcuts

Research Clusters

Research projects

Written about IMS

View all news

Publications

Publications available in DiVA

Researchers

Staff

PhD Students

Guest Researchers and Postdocs

2025

2024

2023

2022

2021

2020

2019

2018

Affiliated Researchers

Research Network

Expert Panel

Education

PhD Studies and Graduate Schools

PhD Studies and Graduate Schools

Master programmes

Courses

Previous Activities

Archive

Concluded Research

Seminars etc

Conferences and Workshops

2019

2018

2016

2013

2012

2011

2010

2009

2008

2007

2005

Researcher Interviews

Lars Elleström on Media Relations

Liviu Lutas on transmediality and intermedial ecocriticism

Makai Péter Kristóf on evolution as represented in popular media

Beate Schirrmacher and Corina Löwe on Representation of Trials in other Media

Martin Knust on developing critical perspectives on the evolution of news media

Signe Kjær Jensen on animated films, music, and on listening to children's own voices when researching children's media

Open Lecture Series: Meeting Media Minds – Critical Legacies of Lars Elleström