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 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.

LIST OF SCIENTIFIC HIGHLIGHTS

Format: 2017
  • The importance of `silent' mutations in cancer (2014)

    Lehner, Ben (CRG)
    Gabaldón Estevan, Toni (CRG)
    Valcárcel Juárez, Juan (CRG)

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    'Silent’ (or synonymous) mutations change the sequence of a gene without directly altering the sequence of the protein that it encodes.  Through an analysis of the DNA sequences of  >3000 human tumours this study - which involved three ICREA professors from the Centre for Genomic Regulation (CRG) - showed that these silent mutations frequently contribute to cause cancer in humans.  The mechanisms by which these mutations function may be diverse, but it was shown that they often alter how the different parts of a gene are spliced together to encode proteins.   In total, it was estimated that between 1 in 2 and 1 in 5 of the silent mutations observed in known oncogenes (cancer promoting genes) contributed to the development of a tumour.  The computational methodology developed in the study also revealed that genes that cause cancer when they are overexpressed - i.e. when they produce too much protein - often harbour mutations in regulatory regions at the ends of the genes (i.e. in their 3’-untranslated regions).

  • Quantum nonlocality in many body systems (2014)

    Lewenstein, Maciej Andrzej (ICFO)
    Acín Dal Maschio, Antonio (ICFO)

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    Science has recently published a study carried out at ICFO with collaboration from the Institute for Nuclear Research, Hungarian Academy of Sciences, in which the researchers have been able to detect non-locality in many-body quantum systems by constructing multipartite Bell inequalities involving two-body correlations only.

    Numerous studies have been carried out regarding entanglement of many-body quantum systems particles, since it proves to be a fundamental key aspect to understanding their properties. However, very little work has been done concerning the nonlocality of these systems, simply because the known Bell inequalities involve correlations among many parties which are out of reach within the current experimental technology. As a consequence, nonlocality of many-body quantum systems cannot be tested experimentally.

    In this study, entitled “Detecting nonlocality in many-body quantum states”, ICFOnians Jordi Tura, Remigiusz Augusiak, Belen Sainz and ICREA Professors at ICFO Antonio Acín and Maciej Lewenstein, in collaboration with T. Vértesi from Hungary, designed classes of multipartite Bell inequalities constructed from the easiest-to-measure quantities, the two-body correlators. These inequalities are, nevertheless, capable of revealing the nonlocality properties of many-body quantum states, in particular those relevant for nuclear and atomic physics. In addition, the inequalities proposed by this study, can be verified by measuring the total spin components of the particles, which opens a new window to experimental detection of many-body nonlocality in physical systems in which individual particles cannot be addressed.

  • A study suggests that North Africans domesticated cereal crops at least 500 years earlier than previously thought (2014)

    Madella, Marco (UPF)

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    Neolithic North Africans began exploiting cereal crops at least 500 years earlier than previously thought, according to new research published in PLOS ONE.Cereal crops such as wheat and barley were first domesticated in the Near East some 10,500 years ago, then spread west, to Europe and the Mediterranean, and east, through central and south Asia.Working at two Neolithic cemeteries in northern and central Sudan, the researchers examined phytoliths obtained from samples of dental plaque from 20 of the skeletons and from other archaeological deposits. Sometimes referred to as ‘plant stones,’ phytoliths are formed when silica in ground water is taken up by plants and deposited between the cells, giving rise to tiny, skeleton-like structures.The phytoliths were compared to a reference collection to confirm that they were indeed cereal crops. Radiocarbon dating further revealed that the phytoliths predated evidence of cereals previously found in Africa from the Neolithic Fayum.  Those from the cemetery in northern Sudan were at least 7,000 years old, and that those from central Sudan were between 7,500 and 6,500 years old.

  • Generation of a macroscopic singlet state (2014)

    Mitchell, Morgan W. (ICFO)

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    The ancient Greek philosopher Epicurus posed the deeply scientific question "what microscopic entities make up the world we see ?"  His speculations gave us the idea of atoms, and indeed the word "atom."  Only in the 20th century did measurements of Brownian motion, and arguments by Albert Einstein, prove beyond any doubt the existence of atoms.  Today, a twin question continues to resist rational explanation and to challenge our best experimentalists.  The question is "how do these microscopic entities  produce the behaviour we see ?"Striking macroscopic phenomena, including high-temperature superconductivity and exotic magnetic phases, are thought to be produced by large-scale entanglement of spins in matter. These massively entangled states cannot, however, be simulated even on our most powerful computers, so the question remains open whether these hypothesized states of matter really exist. A promising experimental approach, known as quantum simulation, aims to produce and study highly-entangled states in artificial material systems.  Here we have taken a step in this direction, by producing a "macroscopic spin singlet," (MSS) in a cloud of about one million cold atoms.  The MSS is an archetypal entangled state, consisting of a macroscopic number of atoms organized into spin singlets, the same kind of entanglement believed to underlie superconductivity and some exotic magnetic phases.  Our experiment found the majority of the atoms, more than 500.000, participating in the entangled state.  The article, published in Physical Review Letters, highlighted by the editors, and popularized in Scientific American, describes how we used quantum non-demolition measurements to both produce and detect large-scale entanglement.  This brings a very powerful quantum optical technique to the study of quantum many-body physics.

  • Unveiling the mechanisms controlling the regenerative capacity loss during aging (2014)

    Muñoz-Cánoves, Pura (UPF)

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    Dr. Pura Muñoz-Cánoves’ Group recently published in Nature the description of an irreversible ageing process responsible for the loss of regeneration capacity in very old muscle stem cells. In geriatric mice, corresponding to humans of 75 years of age and beyond, muscle stem cells were found to lose their regenerative capacity due to activation of a signaling pathway associated with cellular senescence, a state characterized by the incapacity of the cell to divide. Similar processes may also be involved in muscle degeneration associated with advanced ageing in humans (sarcopenia).Regeneration of skeletal muscle depends on a population of adult stem cells (satellite cells) that are normally in a dormant ‘quiescent’ state, which allows the cells to be activated and divide in response to damage or stress, to eventually form new muscle fibers and repair the damaged muscle. The regenerative functions of these cells are known to decline with ageing. The causes, however, are poorly understood. Pura Muñoz-Cánoves and colleagues have reported that geriatric satellite cells suffer intrinsic irreversible changes that cause the cells to switch from a quiescent state (responsive to external damage and allowing cell expansion) into a permanent senescent state (where satellite cell expansion no longer occurs). This work shows that satellite in old mice (up to 24 months of age) maintain this quiescent state through repressing the expression of p16INK4a (an inhibitor of cell division and proliferation which also induces cell senescence).  In contrast, satellite cells in geriatric mice (28 months and beyond) no longer repress p16INK4a , and this drives cells to enter senescence, constituting a point of “no-return”. Geriatric satellite cells are therefore refractory to activation by tissue damage and incapable of forming new muscle.As cellular senescence mediated by 16INK4a  is also dysregulated in human geriatric muscle stem cells, the findings may provide a basis for attenuating loss of muscle regenerative capacity in geriatric humans.  

  • Infall-driven Protostellar Accretion and the Solution to the Luminosity Problem. (2014)

    Padoan, Paolo (UB)

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    In this work we provide a definitive solution to the protostellar luminosity problem. For many years, astronomers have been puzzled by the low luminosity of protostars, the progenitors of stars. They have also wondered about the origin of the large scatters in the observed luminosities. We have shown that the problem arised from an oversimplification of current star formation models. We overcame the problem, and were able to accuratly reproduce the observed protostellar luminosities, by developing the largest star formation simulation to date, thanks to a very large supercomputer award from NASA High-End Computing.

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