Best Research Achievements

Best Research Achievements

Every year, the University of Ljubljana recognises ten best research achievements from the previous 12 months. This year, we received 45 proposals from 19 members of the University. The Working Group of the Research and Development Committee, comprising Prof. Dr. Maja Bučar, Prof. Dr. Rok Kostanjšek, Prof. Dr. Damjana Rozman, Prof. Dr. Bogdan Štefane, Prof. Dr. Miha Škerlavaj, Assoc. Prof. Dr. Nadja Zgonik, Asst. Prof. Dr. Tomaž Curk and Vice-Rector Prof. Dr. Matjaž Krajnc, evaluated and finalised the selection of the ten best achievements by focusing on their international impact, comprehensiveness, current relevance for the wider professional and general public, and applicability. All the proposals were assessed equally, regardless of the discipline, and regardless of whether they involved pure or applied research.

The interdisciplinary group of researchers from the Biotechnical Faculty, Faculty of Electrical Engineering, Faculty of Civil and Geodetic Engineering of the University of Ljubljana and the Jožef Stefan Institute (Assoc. Prof. Dr. Boštjan Murovec, a junior researcher Leon Deutsch, Prof. Dr. Blaž Stres) achieved a significant milestone in the production and mass evolutionary analysis of microbial genomes with the development of the MAGO information platform.

Microbes (bacteria, archaea, fungi, protozoa, viruses) perform key metabolic processes. The knowledge of genomes is crucial for modelling their interactions, understanding their physiology and the molecular evolution of life, and the detection of microbes in the environment. Due to the complexity of interactions and the composition of microbial populations, we employ top-down approaches in research such as metagenomics and metatranscriptomics. The main obstacle is the reconstruction of genomes from omics data.

As the first platform to combine different programmes, the Metagenome-Assembled Genomes Orchestra (MAGO) removes this obstacle by drastically simplifying and speeding up the assembly and completion of draft genomes from metagenomes and metatranscriptomes, increasing completeness (MIMAG, MISAG standards) and enabling genome annotation (GenBank) and evolutionary placement (phylogeny of the highest probability) on a large number of markers, and delimitations of species boundaries and genomic operational taxonomic units (ANIs).

MAGO is the first fully parallelised, open source, scalable platform for the mass reconstruction of genomes from environmental omics data and their direct inclusion in the new Genome Taxonomy Database (https://gtdb.ecogenomic.org/). It has been released in three versions appropriate for high-performance computer clusters (HPC, Singularity, Docker, virtual machine) and suitable for research, teaching and industry. It enables the discovery of new microbial groups, both from small single-cell projects and large-scale and complex environmental metagenomes currently running at eight HPCs worldwide. The article by the interdisciplinary group was published in the journal Molecular Biology and Evolution, IF = 14.797, quarter 1, within the top 10 percent in the field.

Source: Murovec B., Deutsch L., Stres, B. Computational Framework for High-Quality Production and Large-Scale Evolutionary Analysis of Metagenome Assembled Genomes. Mol. Biol. Evol., 37 (2020), 593-598. doi: 10.1093/molbev/msz237.

This was found in an international study by the 5C consortium in which Assoc. Prof. Dr. Robert Kaše played a major part. The study establishes an important basis for an emerging field of research dealing with international comparative aspects of careers.

The article based on this study is the result of many years of work in the international research consortium 5C, “Cross-Cultural Collaboration on Contemporary Careers”, whose primary purpose is to examine the differences in perceptions of careers around the world. Dr. Robert Kaše, Associate Professor of Management and Organisation at the School of Economics and Business of the University of Ljubljana, joined the consortium from Slovenia. The article examines how people in different countries perceive career success in relation to the cultural-institutional environment in which they are embedded. An innovative methodological approach is employed that combines the network analysis technique developed at the University of Ljubljana and a qualitative comparative analysis (QCA).

Using the theory of the influence of institutions in an analysis of data from 13 countries and assessment of data significance, the article proposes four archetypes of the perception of subjective career success linked to typical configurations of institutional factors in the environment. The article establishes an important basis for an emerging field of research dealing with international comparative aspects of careers. In addition, the article is a clear example of the benefits and challenges of a highly inclusive process in an international research consortium.

Source: KAŠE, Robert, DRIES, Nicky, BRISCOE, Jon P., COTTON, Richard D., APOSPORI, Eleni, BAGDADLI, Silvia, ÇAKMAK-OTLUOĞLU, K. Ővgű, CHUDZIKOWSKI, Katharina, DYSVIK, Anders, GIANECCHINI, Martina, SAXENA, Richa, SHEN, Yan, VERBRUGGEN, Marijke, ADELEYE, Ifedapo, BABALOLA, Olusegun, CASADO, Tania, CERDIN, Jean-Luc, KIM, Najung, KUMAR MISHRA, Sushanta, UNITE, Julie, FEI, Zhangfeng. Career success schemas and their contextual embeddedness: a comparative configurational perspective. Human resource management journal, ISSN 0954-5395, Spec. ed., Jul. 2020, vol. 30, iss. 3, pp. 422-440.

Prof. Dr. Mitja Velikonja from the Department of Cultural Studies at the Faculty of Social Sciences of the University of Ljubljana published a monograph on the importance of political graffiti and street art as a subversive political medium in our region with the renowned Routledge Publishing House.

This is the first book worldwide to deal extensively with current political graffiti and street art as a subversive political medium in both our region and the broader global context, first theoretically and methodologically, and then empirically. It is based on two decades of the author's systematic fieldwork on several continents and approximately 25,000 original photographs.

The book is divided into two main parts: the first three chapters are dedicated to terminological, theoretical and methodological reflections. These bases are verified in the second, empirical part through eight case studies examining topics such as pro- and anti-Yugoslav graffiti, appropriations of Triglav in graffiti, comparisons of Balkan nationalist graffiti, hate speech in graffiti, pro- and anti-refugee graffiti, fan graffiti, etc.

The book represents an original and essential contribution to (sub)cultural studies in the contemporary Balkans and Central Europe, transitology, visual cultural studies, art theory, anthropology, sociology, and studies of radical politics. The book was supported by a number of renowned researchers in this field, who contributed short notes to the text:

  • Maria Todorova (University of Illinois at Urbana-Champaign),
  • Dubravka Ugrešić (writer and publicist),
  • Igor Štiks (writer, Singidunum University in Belgrade),
  • Paul Mojzes (Rosemont College),
  • Jasmin Mujanović (publicist from the USA),
  • Svein Mønnesland (University of Oslo) and
  • Volker Berghahn (Columbia University).

The author will also use the book as study material in courses at all three levels of study at the Faculty of Social Sciences and the Academy of Fine Arts and Design of the University of Ljubljana. This academic year, he used it as a visiting professor in his course at Yale University European Studies Council. The book was launched at Columbia University in New York on 19 November this year. Next year it will be published in Slovene by Mladinska knjiga, and it is expected to be published in Polish by the academic publishing house Universitas from Kraków.

Source: Velikonja M. (2019). Post-socialist Political Graffiti in the Balkans and Central Europe. New York, London: Routledge

The methodology for the global evaluation of solar power plants with the new Köppen-Geiger-Photovoltaic (KGPV) classification scheme developed at the Faculty of Electrical Engineering of the University of Ljubljana classifies the Earth into 12 zones.

With the increase in renewable energy sources, particularly solar power plants, the introduction of simple and robust solutions for classifying the suitability of areas for solar energy generation is crucial for the global evaluation of the energy potential and efficiency of solar power plants and the aging of photovoltaic systems.

On the basis of research, a group of researchers from the Laboratory for Photovoltaics and Optoelectronics (LPVO) of the Faculty of Electrical Engineering of the University of Ljubljana (Julian Ascencio-Vasquez, Dr. Kristijan Brecl and Prof. Dr. Marko Topič) developed a new methodology that divides the entire Earth into 12 photovoltaic climate zones. The new KGPV classification scheme upgrades the established Koeppen-Geiger (KG) climate zone scheme with key climatic parameters for photovoltaics and determines 12 zones (Figure). The developed scheme was applied in a study on the suitability of the construction of solar power plants at the global level, and in PV performance projections by 2100 under various climate change scenarios.

The contribution to the global development of photovoltaics and the importance of a simple climate classification for photovoltaics is illustrated by the publication of a news item in PV Magazine Int. summarising the research results.

The methodology was developed as part of the doctoral research by a junior researcher Julian Ascencio-Vasquez. The scientific article describing the methodology and zone classification for photovoltaics at the global level was published in the journal Solar Energy. The article published in the journal attracted a huge readership, and it is the one in Solar Energy that readers downloaded most often in the first 90 days after its publication.

Source: ASCENCIO-VÁSQUEZ, Julián, BRECL, Kristijan, TOPIČ, Marko. Methodology of Köppen-Geiger-Photovoltaic climate classification and implications to worldwide mapping of PV system performance. Solar energy, ISSN 0038-092X, Oct. 2019, vol. 191, pp. 672-685. https://www.sciencedirect.com/science/article/pii/S0038092X19308527, doi: 10.1016/j.solener.2019.08.072. [COBISS.SI-ID 12728916].

The authors (doctoral student Lucas Sa and Pedro Ribeiro from the University of Lisbon and Prof. Dr. Tomaž Prosen from the Faculty of Mathematics and Physics of the University of Ljubljana) show that the distribution of the ratios between the spacings of a randomly selected own value of a non-Hermitian operator to the nearest and next-to-nearest neighbours is a very robust statistic that successfully diagnoses integrability (exact solvability), or, alternatively, chaos, in a wide panel of dissipative quantum and classical stochastic systems.

Quantum chaos is a field of theoretical and mathematical physics with a large number of possible applications, from condensed matter physics and atomic physics to high energy physics and the holographic theory of black holes. One of the main problems is quantum chaos diagnostics (or the absence of an exact solution/integrability), which is particularly problematic in multiparticle systems without any proper classical correspondence or in the absence of a small effective coupling constant. The only robust indication of chaos in such systems is matching the prediction of random-matrix theory. It is especially important to find an indicator that is robust and universal, i.e. independent of the non-universal properties of the model, such as the density of states.

In their scientific work, Sa, Ribeiro and Prosen introduced new universal statistic which is adapted to non-Hermitian or non-normal operators with a complex spectrum, and which is completely independent of the density of states or spectral density in the complex plane and of other details of the model. This statistic of the ratios between the spacings of a randomly selected own value to the nearest and next-to-nearest neighbours shows the universal behaviour in limit cases of the spectra with Poisson statistics which we expect in integrable models, and the spectra of the Ginibre ensemble of non-Hermitian Gaussian random matrices expected in the case of chaotic dissipative models. The new method was successfully tested in the detection of integrability in open quantum multiparticle systems and in classical stochastic (Markov) systems.

Source: Lucas Sa, Pedro Ribeiro in Tomaž Prosen, Complex Spacing Ratios: A Signature of Dissipative Quantum Chaos, Physical Review X 10, 021019 (2020)

Machine learning methods and artificial intelligence have become a driver for change in science, engineering and society. Computational approaches that can extract interesting patterns from comprehensive databases and develop predictive models are becoming ubiquitous. But only a few experts and even fewer lay individuals understand the basics of data science. What is needed is the democratisation of machine learning and the development of ways in which we can explain to anyone on a conceptual level what machine learning can do and how it can be used. The Bioinformatics Laboratory at the Faculty of Computer and Information Science of the University of Ljubljana developed a suitable environment, computational techniques and pedagogical approaches for this purpose.

In articles published in the journals Nature Communications and Bioinformatics, the researchers from the Faculty of Computer and Information Science (researcher Dr. Primož Godec, Assistant Matjaž Pančur, Technical Specialist Aleš Erjavec, Assistant Ajda Pretnar, Prof. Janez Demšar, Assistant Marko Toplak, researcher Jaka Kokošar, researcher Vesna Tanko, Assistant Pavlin Gregor Poličar, Assistant Lan Žagar, researcher Jan Hartman, Prof. Blaž Zupan) and Prof. Uroš Petrovič from the Biotechnical Faculty described and proposed an approach that facilitates the use of machine learning techniques, offering it to domain experts from biomedical laboratories for the purposes of image analysis (Nature Communications) or analysis of the expression profiles of individual cells (Bioinformatics).

The proposed approach is based on the Orange environment being developed in the Bioinformatics Laboratory. Orange employs visual programming with which the user determines the course of an analysis by assembling the basic analytical building blocks. In the article published in the journal Nature Communications, the authors presented the use of this tool in four different image collections, including mouse bone healing, the development of mouse egg cells, morphogenesis of social amoebae, and protein localisation in yeast cells. They demonstrated that accurate models for predicting phenotypes can be easily constructed in the Orange environment from image collections.

A different problem, but again with the application of the visual programming approach, was addressed in the article published in the journal Bioinformatics, where they presented the use of the Orange environment to analyse the gene expressions of individual cells. Here as well, the main achievement is the breaking down of the data analysis problem into simple analytical building blocks which the user can then stack like Lego blocks into an analytical scheme to search for laws in a given set of data by combining graphical representations, building models and interactive research interfaces. Although the articles focus on molecular biology domains, the approach they have developed is generally applicable in science, industry and elsewhere where we handle data.

Source: Godec P., Pančur M., Ilenič N., Čopar A., Stražar M., Erjavec A., Pretnar A., Demšar J., Starič A., Toplak M., Žagar L., Hartman J., Wang H., Bellazzi R., Petrovič U., Garagna S., Zuccotti M., Park D., Shaulsky G., Zupan B. (2019). Democratised image analytics by visual programming through integration of deep models and small-scale machine learning, Nature Communications 10(1):4551. doi: 10.1038/s41467-019-12397-x, [COBISS.SI-ID 32755751], IF(2019)=12.1, »multidisciplinary sciences«: 1A1 (Z, A'', A', A1/2). Stražar M., Žagar L., Kokošar J., Tanko V., Erjavec A., Poličar P., Starič A., Demšar J., Shaulsky G., Menon V., Lamire A., Parikh A., and Zupan B. (2019). scOrange – A Tool for Hands-On Training of Concepts from Single Cell Data Analytics, Bioinformatics 35(14):i4-i12, doi: 10.1093/bioinformatics/btz348, [COBISS.SI-ID 1538307523], IF(2019)=5.6, »mathematical & computational biology«: 1A1 (Z, A'', A', A1/2).

Based on thirty years of monitoring of Slovenian youth, the researchers at the Faculty of Sport of the University of Ljubljana identified a halt to the trend of being overweight and obese before the onset of the COVID-19 epidemic.

Obesity in children has been linked to both short- and long-term adverse health outcomes. Moreover, childhood obesity tracks well into adulthood, and leads to risks of premature mortality. Childhood obesity increased dramatically over the last few decades of the twentieth century, especially in developed countries Since then childhood obesity has been recognised as public health priority, as a result of which various preventive strategies are being implemented worldwide.

Despite such efforts, no country had previously presented reliable evidence on the achievement of a reversal of this trend, but the researchers of the Faculty of Sport at the University of Ljubljana were the first to do so on the basis of the SLOfit data (Research Fellow Dr. Maroje Sorić, Prof. Gregor Jurak, Asist. Saša Đurić, Prof. Marjeta Kovač, Prof. Janko Strel and Assoc. Prof. Gregor Starc). On the basis of 6,738,510 data points collected in a thirty-year period of measuring the body mass of Slovenian children and adolescents in the period 1989–2018, they examined the prevalence of being overweight and obese in three age groups (7–10, 11–14 and 15–18 years).

They found that obesity almost tripled between 1989 and 2009, while the incidence of being overweight doubled in both sexes, but during the last decade this trend was reversed or at least stopped. This reversal of the trend was more pronounced in boys than in girls, and in young children compared to adolescents.

The perceived trends are least favourable for adolescents, especially female adolescents with the still growing trend of being overweight and obese indicating a need for interventions tailored specifically to these groups. Despite a noticeable reduction in being overweight and obese among Slovenian children and adolescents, both rates are still very high. The existing efforts to combat obesity should therefore continue with unabated intensity. The results are published in the seventh most-cited journal in the world, Scientific Reports – Nature, with an impact factor of 4.576.

Source: SORIĆ, Maroje, JURAK, Gregor, ĐURIĆ, Saša, KOVAČ, Marjeta, STREL, Janko, STARC, Gregor. Increasing trends in childhood overweight have mostly reversed: 30 years of continuous surveillance of Slovenian youth. Scientific reports, ISSN 2045-2322, 3. Jul. 2020, vol. 10, article no. 11022, str. 1–8, ilustr. https://www.nature.com/articles/s41598-020-68102-2. epdf?sharing_token=gMTtUKi47j8Ry6s86Cqsf9RgN0jAjWel9jnR3ZoTv0MaNa_8Qc64WJ7troUHlHY6CNqvAfhtXzT9n758unRW0cjQRLXjCLiHM5Rh6YnMn8khj3siyLC-BAwKM kVnoPcmYrfQjzF94FkDqNfJwSLsCp_Hv88XHSFBeL0J6WrzLbc%3D, https://www.nature.com/articles/s41598-020-68102-2, doi: 10.1038/s41598-020-68102-2.

Researchers from the Faculty of Medicine and the Faculty of Arts at the University of Ljubljana found a reduction in spatial working memory capacity in adolescents with type 1 diabetes (T1D) in comparison to healthy peers during acute hypoglycaemia, while there were no statistically significant differences between the two groups when blood sugar levels were normal.

Children with T1D experience mild cognitive changes in comparison to healthy peers. The reasons for this are not yet known. The objective of the researchers from the Faculty of Medicine of the University of Ljubljana (Jasna Šuput Omladič (lead author), Dr. Andrej Vovk, Prof. Dušan Šuput, Asst. Prof. Klemen Dovč, Assoc. Prof. Nataša Bratina, Asst. Prof. Magdalena Avbelj Stefanija, Prof. Tadej Battelino (corresponding author)) and the Faculty of Arts of the University of Ljubljana (Dr. Anka Slana Ozimič) and Prof. Grega Repovš was to investigate the effect of acute hypoglycaemia on brain function in adolescents with T1D.

The study took the form of an open clinical study. It included 20 participants with T1D (aged 14.64 ± 1.78 years) and 20 age-matched healthy control subjects (aged 14.40 ± 2.82 years). All participants underwent structural MRI and completed two functional MRI sessions. Participants with T1D completed the first functional MRI session with a normal blood sugar concentration and the second with a blood sugar concentration increased by 20 mmol/L; blood sugar concentration was not changed in the control group.

In comparison to healthy peers, a reduction in spatial working memory capacity occurred in the group with T1D during acute hypoglycaemia. When blood sugar values were normal there was no statistically significant difference between the two groups. As far as the researchers are aware, this is the first study to look at brain activation during acute hypoglycaemia.

Acute hypoglycaemia negatively affects spatial working memory capacity in adolescents with T1D. This may be because of poorer brain activation during the stimulus-encoding phase. Reduced spatial working memory capacity is relevant for daily functioning and can affect the academic performance of this age group.

Using advanced MRI techniques and spectroscopy, the authors also indicated the most probable cause of impaired brain function, since they observed a reduction in the concentration of all measured metabolites in brain tissue, which points to the formation of micro-oedemas in the brain caused by hypoglycaemia.

Reference: ŠUPUT, Jasna, SLANA OZIMIČ, Anka, VOVK, Andrej, ŠUPUT, Dušan, REPOVŠ, Grega, DOVČ, Klemen, BRATINA, Nataša, AVBELJ, Magdalena, BATTELINO, Tadej. Acute hyperglycemia and spatial working memory in adolescents with type 1 diabetes. Diabetes Care, ISSN 0149-5992, Aug 2020, Vol. 43, No. 8, pp. 1941–1944.

Researchers from the Faculty of Medicine and the Faculty of Mathematics and Physics of the University of Ljubljana became the first in the world to discover phase transitions to a nonequilibrium chiral state in liquid crystals and explain this in theoretical terms.

The orientational order in liquid crystals has a key influence on the remarkable optical properties of these anisotropic liquids and is at the same time responsible for their unusual rheological response. The structural regulation of liquid-crystal molecules in microfluidic channels can be precisely controlled using modern research equipment by surface treatment, temperature change and flow regulation with adjustable pressure difference.

The research group from the University of Ljubljana (Simon Čopar (lead author), assistant professor of physics at the Faculty of Mathematics and Physics; Žiga Kos, postdoctoral researcher at the Faculty of Mathematics and Physics and at MIT (USA), Tadej Emeršič, former junior researcher at the Faculty of Medicine and current postdoctoral researcher at the University of Chicago (USA) and Asst. Prof. Uroš Tkalec (corresponding author), research associate at the Faculty of Medicine), which was led by Dr. Tkalec, reported in Nature Communications (impact factor 12.12) on the experimental establishment, dynamic stabilisation and theoretical analysis of previously unobserved but topologically significant chiral states which they had previously only studied under equilibrium conditions. The authors of the research explained the mechanism of the sequence of phase transitions between topologically different states in the pressure-driven flow of a liquid crystal using a phenomenological model based on the anisotropy of elastic constants that logically complements the phase diagram of all possible hydrodynamic states. The work thus completes a decade-long period of research in the field of nematofluidics and promises the application of these concepts in lyotropic and active liquids with nematic order.

The research has met with a notable response from other experts, with Dr. Tkalec lecturing on it at the University of Chicago, ESPCI Paris and Johns Hopkins University and at the Gordon Research Conference in the USA. At the invitation of the editors, the paper has been presented in popular form on the Nature Research Device and Materials Engineering Community website and additionally promoted on the Nature Research Instagram feed. A review article on these findings has also been published by the French research equipment manufacturer Elveflow on the Microfluidic Reviews page of its website. Last but not least, the achievement has contributed to enabling two of paper’s co-authors to continue their postdoctoral research at two prestigious institutions: MIT and the Pritzker School of Molecular Engineering at the University of Chicago.

Reference: ČOPAR, Simon, KOS, Žiga, EMERŠIČ, Tadej, TKALEC, Uroš. Microfluidic control over topological states in channel-confined nematic flows. Nature Communications, ISSN 2041-1723, Jan 2020, Vol. 11, Art. No. 59: https://www.nature.com/articles/s41467-019-13789-9.

A group of researchers from the Faculty of Natural Sciences and Engineering of the University of Ljubljana (UL NTF), the Scientific Research Centre of the Slovenian Academy of Sciences and Arts (ZRC-SAZU), the Jožef Stefan Institute (JSI) and the CNRS and LSCE institutes from France studied 6,600 years of the impacts of climate and humans on Lake Bohinj.

Today the impact of human activity on nature is immense. It is so significant that we rarely find pristine environments on Earth. When and to what extent did this “devastating" influence of man begin? An international team of researchers (UL NTF (Prof. Andrej Šmuc, (lead author), Assoc. Prof. Matej Dolenec, (co-author), ZRC-SAZU (Dr. Maja Andrič, first author), JSI (Prof. Nives Ogrinc) and the CNRS and LSCE institutes from France) was searching for the answer to this question deep down at the bottom of Lake Bohinj in sedimentary archives that have been recording natural and anthropogenic environmental changes for more than 10,000 years.

They reconstructed the evolution of the wider surrounding area of Bohinj over the last 6,600 years on the basis of a wide range of interdisciplinary research on environmental proxies (geochemistry, sedimentology, isotopes, palynology, archaeology). The most shocking discovery was not that the impact of humans (agriculture, grazing, mining) has been significant since the Bronze Age, but that it was already catastrophic more than 3,000 years ago. Since the arrival of people, their activities have affected flora and fauna as well as erosion, soil evolution and the hydrology of the lake, thus completely changing the landscape of Bohinj.

Another interesting fact: in the past, the water did not flow into Lake Bohinj only from the direction of the Savica River (as it does today), but also from the opposite direction, from Stara Fužina. The researchers attribute this phenomenon to changes in climate and a wetter climate.

The research and the resulting article is unique in the entire Mediterranean area, since it opens up new horizons with regard to the more than 6,000-year-old fragile balance between the natural and human orders that determine the origin and existence of today's landscape. The article was published in the journal A'' and is one of the outstanding achievements.

Source: Andrič M., Sabatier P., Rapuc W., Ogrinc N., Dolenec M., Arnaud F., Grafenstein U., Šmuc A. 6600 years of human and climate impacts on lake-catchment and vegetation in the Julian Alps (Lake Bohinj, Slovenia). Quat. Sci. Rev., 227 (2020), 1–18.