Highlights

Every year, a committee of experts sits down with a tough job to do: from among all ICREA publications, they must find a handful that stand out from all the others. This is indeed a challenge. The debates are sometimes heated and always difficult but, in the end, a shortlist of  the most outstanding publications of the year is produced. No prize is awarded, and the only additional acknowledge is the honour of being chosen and highlighted by ICREA. Each piece has something unique about it, whether it be a particularly elegant solution, the huge impact it has in the media or the sheer fascination it generates as a truly new idea. For whatever the reason, these are the best of the best and, as such, we are proud to share them here.

LIST OF SCIENTIFIC HIGHLIGHTS

Format: yyyy
  • Super resolution microscopy reveals how DNA supercoiling shapes the genome (2021)

    Cosma, Maria Pia (CRG)

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    Super resolution microscopy reveals how DNA supercoiling shapes the genome

    The biological mechanisms that enable the DNA to be squeezed into a tight space in each human cell is matter of deep investigation. In this condensed state, the DNA, also known as chromatin, contains many loops that bring together different regions of the genome that would normally be far apart. The resulting physical proximity is important for transcribing DNA into RNA which then makes proteins, making chromatin looping a fundamental biological mechanism for human health and disease.

    In this work we pictured individual loops of DNA. The images reveal how the human genome organises itself in three-dimensional space at much higher resolution than previously possible. Moreover, we found that DNA supercoiling, which is produced as a byproduct of transcription activity, generates a force that causes structural proteins known as cohesins to ‘surf’ across DNA strands and generate loops, finally morphing the overall shape of the genome.

  • SARDO: Rescuing Lost Victims through their Mobile Phones with Drones (2021)

    Costa Perez, Xavier (i2CAT)

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    SARDO: Rescuing Lost Victims through their Mobile Phones with Drones

    Natural disasters affect millions of people every year. Finding missing persons in the shortest possible time is of crucial
    importance to reduce the death toll. This task is especially challenging when victims are sparsely distributed in large and/or
    difficult-to-reach areas and cellular networks are down.

    Unmanned Aerial Vehicles (UAVs) or Drones have recently emerged as a cost-efficient alternative to address emergency scenarios for multiple reasons. First, UAVs can be rapidly deployed in disaster areas providing on-demand mobile networks. Second, UAVs may rapidly approach difficult-to-reach locations, such as mountains, deserts, or devastated areas and cover large search areas with sparse victims distribution. Finally, given the high penetration rate of mobile devices in our society, it can be reasonably assumed that victims are equipped with smart devices, e.g., smart phones and wearables, that can be detected by UAV mobile networks.

    In this work we present SARDO, a drone-based search and rescue solution that leverages the high penetration rate of mobile phones
    in the society to localize missing people. SARDO is an autonomous, all-in-one drone-based mobile network solution that does not
    require infrastructure support or mobile phones modifications. It builds on novel concepts such as pseudo-trilateration combined with
    machine-learning techniques to efficiently locate mobile phones in a given area.

    Our results, with a prototype implementation in a field-trial, show that SARDO rapidly determines the location of mobile phones (~3 min/UE) in a given area with an accuracy of few tens of meters and at a low battery consumption cost (~5%).

    State-of-the-art localization solutions for disaster scenarios rely either on mobile infrastructure support or exploit onboard cameras for
    human/computer vision, IR, thermal-based localization. To the best of our knowledge, SARDO is the first drone-based cellular
    search-and-rescue solution able to accurately localize missing victims through their mobile phones.

  • Towards quantum repeaters: Telecom heralded entanglement between solid-state quantum memories (2021)

    de Riedmatten, Hugues (ICFO)

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    Towards quantum repeaters: Telecom heralded entanglement between solid-state quantum memories

    Entanglement is one of the main properties of quantum physics, which leads to very strong correlations between spatially separated systems. The distribution of entanglement between the nodes of a quantum network will allow new advances e.g. in long distance quantum communication, distributed quantum computing and quantum sensing. On the ground, quantum information can be distributed across the nodes using single photons at telecommunication wavelengths traveling in optical fibers. The maximal distance that can be reached in optical fibers with direct transmission is however limited to a few hundred km due to the loss in the fiber. In classical communications, this problem is solved by placing amplifiers every 50 to 100 km in the fiber network (so called repeaters). However, this kind of repeaters cannot be used with quantum bits, due to the unavoidable noise they produce. One solution to reach longer, continental distances is to use quantum repeaters which use entanglement between quantum memories as main building block.

    In a study published in Nature that was featured on the cover of the issue, ICFO researchers led by ICREA Prof. Hugues de Riedmatten , have achieved entanglement between two solid-state quantum memories located in different laboratories 10 m appart. The entanglement was heralded by a photon at teleccomunication wavelength and stored in the quantum memories in a multiplexed fashion.  These two key features have been achieved together for the first time and define the stepping stone in extending this scheme to much longer distances.

    These results constitute an important milestone towards the practical realization of quantum repeaters using the installed fiber optic telecom network.

     

  • Revisiting the Global Workspace orchestrating the hierarchical organisation of the human brain (2021)

    Deco, Gustavo (UPF)

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    Revisiting the Global Workspace orchestrating the hierarchical organisation of the human brain

    It has been proposed that the human brain is similar to an orchestra in that it is hierarchically organised but that there is unlikely to be just a single conductor. In 1988 B Baars proposed the concept of a ‘global workspace’, where information is integrated in a small group of ‘conductors’ before being broadcast to the whole brain. This celebrated theory is an elegant solution to how hierarchical organisation allows the brain to orchestrate function and behaviour by organising the flow of information and the underlying computations necessary for survival. As such, this is a theory of consciousness as pointed out by neuroscientists S Dehaene and JP Changeux, who proposed the ‘global neuronal workspace’ hypothesis where associative perceptual, motor, attention, memory, and value areas interconnect to form a higher-level unified space where information is broadly shared and broadcast back to lower-level processors. Colloquially, the brain’s global workspace is akin to a small core assembly of people in charge of an organisation, like a group of many conductors leading an orchestra.

    It has not been known where and how this orchestration takes place in the brain. Now in ”Revisiting the Global Workspace orchestrating the hierarchical organisation of the human brain”, Nature Human Behaviour, researchers found the existence of a functional ‘rich club’ of brain regions incarnating this ‘global workspace’. This radical new discovery from Gustavo Deco and Morten L Kringelbach’s international collaboration is based on a large dataset of over 1000 human participants with fMRI recordings. The findings shed new light on the nature of consciousness.

    Deco: “To identify the global workspace, we determined the information flow between brain regions by means of a normalised directed transfer entropy framework applied to multimodal neuroimaging data from healthy participants. This revealed a set of unique brain regions orchestrating information from perceptual, long-term memory, evaluative and attentional systems across many different tasks. Also, we confirmed the causal significance and robustness of our results by systematically lesioning a generative whole-brain model”.

  • Want to tell 'blue' from 'green'? Avoid too much sun... (2021)

    Dediu, Dan (UB)

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    Want to tell 'blue' from 'green'? Avoid too much sun...

    Not all languages "cut" the spectrum of visible light into words for colours in the same way. While some languages function perfectly well with just 2 or 3 basic colour terms (roughly "light", "dark", and "red"), others have more than 10. In particular, while languages such as English, French and Spanish have a single basic term for the 'blue' region of the visible spectrum ("blue", "bleu" and "azul", respectively) and some even distinguish two shades (such as Russian: light "goluboy"/"голубой" and dark "siniy"/"синий"), many other languages do not make the difference between 'blue' and 'green', using instead a single basic colour term roughly translatable as "grue". Why do these differences between languages exit?

    To answer, we used a massive database of 142 populations spread across the globe, speaking widely different languages, and we showed that the languages spoken by more people, closer to large lakes, or further away from the equator, have a higher chance of distinguishing 'blue' and 'green'. While the first factor really is just an imperfect proxy for more complex technologies (including dyeing techniques) and the second seems to intuitively make sense (not all lakes are always "poster card" blue, but they are very salient and important parts of life), the third supports an older but intriguing suggestion.

    Long exposure, throughout the lifespan, to lots of ultraviolet light, especially to the medium-wave or type "B" (UV-B), has negative effects on the lens of the eye, resulting in progressive "lens brunescence" and decreased sensitivity to blue light. This progressive loss of blue light perception, acquired through unprotected exposure to intense UV-B light, would explain why languages closer to the equator (where UV-B intensity is higher) tend to not distinguish 'blue' and 'green'. However, this is just one factor among many others, but it brings home the fact that languages "live" in the real world and are shaped by it in complex and fascinating ways. 

  • Use of quantitative models to predict gene expression (2021)

    Di Croce, Luciano (CRG)

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    Use of quantitative models to predict gene expression

    Appropriate regulation of gene expression is necessary for correct development and homeostasis of organisms. Epigenetic mechanisms represent an additional layer of information, besides the genetic sequence, crucial for the correct functioning of each cell. Histone modifications, which modulate and are associated to transcriptional activation or repression, are a major epigenetic feature.

    We develop quantitative models to characterize the relationship of gene expression with histone modifications at enhancers or promoters. We use embryonic stem cells (ESCs), which contain a full spectrum of active and repressed (poised) enhancers, to train predictive models. As many poised enhancers in ESCs switch towards an active state during differentiation, predictive models can also be trained on poised enhancers throughout differentiation and in development. Remarkably, we determine that histone modifications at enhancers, as well as promoters, are predictive of gene expression in ESCs and throughout differentiation and development. Importantly, we demonstrate that their contribution to the predictive models varies depending on their location in enhancers or promoters. Moreover, we use a local regression (LOESS) to normalize sequencing data from different sources, which allows us to apply predictive models trained in a specific cellular context to a different one. We conclude that the relationship between gene expression and histone modifications at enhancers is universal and different from promoters. Our study provides new insight into how histone modifications relate to gene expression based on their location in enhancers or promoters.