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 24 publications 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.


Format: yyyy
  • New physics effects in fusion plasmas revealed by three-dimensional computations   (2019)

    Mantsinen, Mervi Johanna (BSC-CNS)

    view details

    New physics effects in fusion plasmas revealed by three-dimensional computations  

    Shear Alfvén instabilities are of considerable interest in fusion plasma research. These instabilities can be driven by energetic particles such as fusion products. Not only can the Alfvén instabilities degrade the confinement and heating efficiency of energetic particles by channeling them but they can also cause severe damage to the plasma-facing components of the plasma confining vessel through high heat fluxes. Thus, investigations of their control, better performance and comprehensive understanding are required.

    We have carried out detailed modelling and analysis of experimentally observed energetic particle-driven Alfvénic instabilities in tokamak and stellarator plasmas using three dimensional (3D) numerical tools based on the reduced magnetohydrodynamics (MHD) model.

    To explain experimental observations of Alfvén instabilities in TJ-II flexible heliac plasmas, we have compared experimental results with the results obtained through theoretical model of shear Alfvén waves in a 3D toroidal geometry and obtained qualitative agreement.

    We have also modelled bifurcated MHD equilibria with 3D helical core surrounded by an axisymmetric 2D mantle for the ASDEX Upgrade tokamak plasmas and compared them to an axisymmetrical 2D case (cf. figure). Our modelling results reveal interesting new physics effects due to 3D helical core such as continuum splitting and variation of mode frequency around the frequency accumulation point as well as new frequency gaps due to helical distortion.

  • Research on HIV/AIDS enables new treatments for Ebola virus (2019)

    Martínez Picado, Javier (IrsiCaixa)

    view details

    Research on HIV/AIDS enables new treatments for Ebola virus

    Dendritic cells are the most potent antigen presenting cells found in humans and their immune function is key to initiate immunity against invading viruses. These cellular sentinels patrol distinct mucosae and upon infection, viral sensing triggers rapid innate immune responses that might initially contain viral spread. Activation of dendritic cells subsequently elicits their cellular migration towards lymphoid tissues, where they trigger a more selective immune response against the assaulting pathogens.

    In 2012, while working on immune pathogenic mechanisms involving HIV-1 –the AIDS virus–, the retrovirology team at the IrsiCaixa AIDS Research Institute described a new interaction between specific glycolipids (dubbed gangliosides) in the viral membrane and the protein Siglec-1 (or CD169) on the dendritic cell membrane. The characterization of this new ligand-receptor interaction opened a wide range of translational possibilities, not only including HIV-1 control, but also other enveloped viruses.

    Filoviruses, such as Ebola virus, cause a severe fever having a very high case fatality rate. Since 1976 several Ebola viruses cause outbreaks in humans. The largest one ever recorded occurred in West-Africa between 2014-2016, with 28,646 infected patients and 11,323 reported deaths. At that time, the research group was investigating other potential ganglioside-containing viruses that could exploit Siglec-1 as an attachment receptor in myeloid cells, which are in vivo targets of filoviruses. They have now found that Ebola virus-like particles also bind to Siglec-1 on activated dendritic cells upon recognition of their gangliosides.

    This observation opens the door to develop pan-viral inhibitors based on this mechanism of action. The team has generated a series of monoclonal antibodies that specifically bind to Siglec-1. Blockage of the Siglec-1 receptor by anti-Siglec-1 antibodies halts Ebola viral uptake and cytoplasmic entry, offering cross-protection against other ganglioside-containing viruses such as HIV-1. As a result, two patents have been filed to protect these antibodies as potential therapeutic agents.

  • Color Superconductivity, Neutron Stars and Holography  (2019)

    Mateos, David (UB)

    view details

    Color Superconductivity, Neutron Stars and Holography 

    Under ordinary conditions quarks and gluons are confined inside the protons and neutrons contained in the atoms that make us and the things around us. However, quarks and gluons may form a completely different type of matter at the core of neutron stars, where the strong gravitational force compresses them to the highest densities known in Nature. It is conjectured that one such phase may be a "color superconductor". This is an analog of the ordinary electromagnetic superconductors that are used, for example, to make trains levitate. The key difference is that, in a color superconductor, the electromagnetic force is replaced by the strong nuclear force. Color superconductors might be discovered experimentally via the gravitational wave signals emitted in neutron star mergers like the one first detected in August 2017. 

    The presence of the strong nuclear force makes the theoretical description of color superconductors by conventional methods extremely difficult. For this reason we have used a string-theoretical tool known as “holography”, which maps the properties of matter in our four-dimensional world to those of … string theory in ten dimensions!

    We have shown that, in the string theory description, the properties of the color superconductor are encoded in the bending in the extra dimensions of higher-dimensional objects known as "D-branes", as shown in the figure. This geometrization of the problem provides a completely new (and higher-dimensional) perspective on color superconductors. As usual in physics, such a new viewpoint brings with it a new level of understanding that we are just beginning to unravel.

  • Cost-efficient nanodevices for pathogens detection (2019)

    Merkoçi, Arben (ICN2)

    view details

    Cost-efficient nanodevices for pathogens detection

    There is an urgent need for the development of cost-efficient devices for in-field detection of pathogens. Nanobiosensors are a very good alternative for such applications. The first example is an integrated label-free in situ isothermal amplification/detection based on the use of screen-printed electrodes modified with gold nanoparticles and employing impedance for diagnostic of a plant disease (Citrus tristeza virus, CTV). The developed in-situ isothermal amplification/detection sensor showed advantages in terms of simplicity, sensitivity, and portability together with allowing quantitative analysis of nucleic acid. The proposed biosensor is of high potential interest for in-field applications for plant pathogen early detection, which would overcome the limitations of classical molecular methods such as PCR (polymerase chain reaction). The second example includes a fast and reliable way to detect pathogenic bacteria. The developed assay is based on the conversion of an electrochemical signal into a more convenient optical readout for the visual detection of Escherichia coli (E.coli). By electropolymerizing polyaniline (PANI) on an indium tin oxide screen-printed electrode (ITO SPE), we achieved not only the desired electrochromic behavior but also a convenient way to modify the electrode surface with antibodies (taking advantage of the many amine groups of PANI). Applying a constant potential to the PANI-modified ITO SPE induces a change in their oxidation state, which in turn generates a color change on the electrode surface. The presence of E. coli on the electrode surface increases the resistance in the circuit affecting the PANI oxidation states, producing a different electrochromic response. Using this electrochromic sensor, we could measure concentrations of E. coli spanning 4 orders of magnitude with a limit of detection of 102 colony forming unit per 1 mL (CFU mL−1) by the naked eye and 101 CFU mL−1 using ImageJ software. In this work we show that merging the sensitivity of electrochemistry with the user-friendliness of an optical readout can generate a new and powerful class of biosensors, with potentially unlimited applications in a variety of fields.

  • Identifying the Achilles heel of RAS-malignant tumors (2019)

    Milán Kalbfleisch, Marco (IRB Barcelona)

    view details

    Identifying the Achilles heel of RAS-malignant tumors

    More than 30% of all human tumors arise from mutations that encode a RAS protein essentially locked in a constitutively activated form. Despite more than three decades of effort by Academia and Industry, only recently have effective RAS inhibitors started to be identified. We have used the fruit fly Drosophila as model system to identify strategies to specifically eliminate tumor cells that activate this oncogene. We have presented evidence that RAS drives active cell proliferation through the regulation of the G1-S transition, induces DNA damage, and most interestingly, silences the response to this damage by blocking the DNA damage response (DDR) pathway as well as the induction of cell death by the tumor suppressor protein Dp53. Given the inherent induction of DNA damage and additional blockade of the DDR at different levels by the RAS oncogene, we have used genetic or chemical inhibition of ERK activity coupled to ionizing radiation as a therapeutic approach to selectively eliminate RAS-malignant tissues. In particular, we have used TRAMETINIB, a drug prescribed for human melanoma, to inhibit the ability of RAS to block cell death, thus leading to the elimination of malignant tumors—selectively and by cell death—without affecting the development of organs or the flies themselves. Our results open up the possibility of combining radiation therapies with RAS inhibitors to selectively eliminate tumor cells.


  • Single-photon, single-atom matchmaking (2019)

    Mitchell, Morgan W. (ICFO)

    view details

    Single-photon, single-atom matchmaking

    Single trapped atoms are greatly valued in quantum technology. They are ideal standards because they are the same everywhere in the world, they make extraordinary sensors and clocks, and they can be used as nodes in quantum information networks and quantum computing. Because an atom is a truly tiny quantity of matter, special techniques must be used to interface them even to ordinary laser beams. In these works, we approached the problem of strongly coupling a single trapped atom to individual photons and to photon pairs. We built an optical system of four high numerical-aperture lenses around a single 87Rb atom held in an “optical tweezer” trap. This allowed us to shape the photons’ wave-fronts to match the atom’s radiation pattern, to ensure both efficient absorption of single photons by a single atom, and efficient collection of photons emitted by the atom. At the same time, we developed the world’s first source of entangled photon pairs, both of which are resonant to optical transitions in the 87Rb atom. These new technologies enable study of light-matter interactions at the level of individual quanta, of interest to both quantum technologies and other technologies based on light mattter interactions, e.g. super-resolution imaging.