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.


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  • Publication book "Ultracold Atoms in Optical Lattices: Simulating Quantum Many-Body Systems" (2012)

    Lewenstein, Maciej Andrzej (ICFO)
    Sanpera Trigueros, Anna (UAB)

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    Publication book "Ultracold Atoms in Optical Lattices: Simulating Quantum Many-Body Systems"

    The book "Ultracold Atoms in Optical Lattices: Simulating Quantum Many-Body Systems" (Oxford University Press, Oxford, 2012), written by ICREA Research Professors Maciej Lewenstein and Anna Sanpera, and former ICREA researcher Veronica Ahufinger, is the first book ever that treats extensively (460 pages and several thousands references) the rapidly developing subject of quantum computers of special purpose, a.k.a. quantum simulators. Quantum simulators are currently being realized in various experiments, in particular in experiments with ultracold atoms or molecules in optical lattices, or ultracold trapped ions. It is expected that in the next future quantum simulators will help us to understand better quantum many-body phenomena, from high temperature superconductivity to quark confinement. The book focuses on atoms and molecules in optical lattices and, besides providing a general introduction to the subject, it discusses in great detail ultracold atomic/molecular systems that can simulate spin models, dipolar systems, disordered systems, frustrated systems and systems under influence of intense gauge fields. The book focuses on atoms and molecules in optical lattices and, apart of providing general introduction to the subject, discusses in great detail ultracold atomic/molecular systems that can simulate spin models, dipolar systems, disordered systems, frustrated systems and systems under influence of intense gauge fields.

  • The Discovery of a Higgs-Like Boson at the LHC (2012)

    Martínez Pérez, Mario (IFAE)

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    The Discovery of a Higgs-Like Boson at the LHC

    Since 2009, the Large Hadron Collider (LHC) at CERN (Geneva, Switzerland) collides protons at center-of-mass energies of up to 8 TeV, the highest energy ever reached by a particle accelerator. One of the main goals of the LHC is the search for the Higgs boson, the last missing piece of the Standard Model (SM). The Higgs boson is the particle associated with a quantum field postulated to permeate the Universe and responsible for endowing elementary particles with their mass. Unfortunately, the mass of the Higgs boson is not predicted, making its search particularly challenging.
    During the last 48 years, particle physicists have searched for the Higgs boson. In the 90's, the LEP electron-positron collider at CERN concluded that the Higgs boson, if it exists, should have a mass larger than 114.4 GeV at 95% confidence level (C.L). The search continued at the 1.96 TeV proton-antiproton Tevatron collider at Fermilab (Chicago, USA), till the accelerator was shut down on September 2011. While the Tevatron experiments achieved sensitivity to a SM Higgs boson up to a mass of 185 GeV, no definite signal was established.
    On July 4, 2012, under lots of excitement and extensive media coverage, the ATLAS and CMS experiments reported at a public seminar at CERN the results of their searches for the SM Higgs boson using the data collected during 2010-2012. In particular, the combination of searches at the ATLAS experiment excluded at 95% C.L. the presence of a Higgs boson with mass between 111 GeV and 559 GeV, with the exception of the range 122-131 GeV [1]. In this mass range a signal-like excess was observed at a mass of ~126 GeV, primarily in the searches targeting the decay modes into two photons (see Fig. 1) and into four charged leptons (see Fig. 2). The significance of the excess was estimated at 5.9 standard deviations from the background-only hypothesis, with a similar signal also observed by the CMS experiment [2]. This represents the discovery of a new boson with properties compatible with those of the SM Higgs boson, marking the beginning of a new era in particle physics. The ATLAS discovery has been recently discussed in a special edition of the Science journal [3].
    In order to unravel the nature of this particle, precise measurements of its properties are of crucial importance. A. Juste and M. Martínez lead the analysis effort of the ATLAS data at IFAE, playing a central role in those channels where the Higgs boson is produced in association with a pair of top quarks or a Z boson in the final state, and decay

  • Global convergence in the vulnerability of forests to drought (2012)

    Mencuccini, Maurizio (CREAF)

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    Global convergence in the vulnerability of forests to drought

    Shifts in rainfall patterns and increasing temperatures associated with climate change are likely to cause widespread forest decline in regions where droughts are predicted to increase in duration and severity. One primary cause of productivity loss and plant mortality during drought is hydraulic failure. Drought stress creates trapped gas emboli in the water transport system, which reduces the ability of plants to supply water to leaves for photosynthetic gas exchange and can ultimately result in desiccation and mortality. At present we lack a clear picture of how thresholds to hydraulic failure vary across a broad range of species and environments, despite many individual experiments. Here we draw together published and unpublished data on the vulnerability of the transport system to drought-induced embolism for a large number of woody species, with a view to examining the likely consequences of climate change for forest biomes. We show that 70% of 226 forest species from 81 sites worldwide operate with narrow hydraulic safety margins against injurious levels of drought stress and therefore potentially face long-term reductions in productivity and survival if temperature and aridity increase as predicted for many regions across the globe. Safety margins are largely independent of mean annual precipitation, showing that there is global convergence in the vulnerability of forests to drought, with all forest biomes equally vulnerable to hydraulic failure regardless of their current rainfall environment. These findings provide insight into why drought-induced forest decline is occurring not only in arid regions but also in wet forests not normally considered at drought risk.

  • Simple detection of circulating cancer cells using gold nanoparticles (2012)

    Merkoçi, Arben (ICN2)

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    Simple detection of circulating cancer cells using gold nanoparticles

    Circulating tumor cells (CTCs) are traveling cells in physiological fluids that are released from a main tumor or from metastasis. CTC quantification is of great interest for evaluating cancer dissemination, predicting patient prognosis, and also for the evaluation of therapeutic treatments representing a reliable potential alternative to invasive biopsies and subsequent proteomic and functional genetic analysis. In fact, isolation of CTCs from peripheral blood, as a "liquid biopsy", is expected to be able to complement conventional tissue biopsies of metastatic tumors for therapy guidance. A particularly important aspect of a "liquid biopsy" is that it is safe and can be performed frequently, because repeated invasive procedures may be responsible for limited sample accessibility. The main techniques reported for CTC detection consist in their labeling with tagged antibodies (immunocytometry) followed by fluorescence analysis or the detection of the expression of tumor markers by reverse-transcriptase polymerase chain reaction (RT-PCR). However, the required previous isolation of CTCs from the human fluids is limited to complex analytic approaches that often result in a low yield and purity. Merkoçi's groups in collaboration with colleagues at UAB have achieved a novel and rapid and simple detection of cancer circulating cells using gold nanoparticles (AuNP). The electrochemical detection and the characterization results demonstrate that this method is selective to Caco2 CTC and that the electrochemical signal is not affected by the presence of other circulating cells. The achieved detection is selective for the target tumor cells and can exclude the false positive results. The main advantages of the presented method compared with the already reported for CTC detection rely on the sensitive and quantitative electrochemical detection technique used in addition to the excellent properties of the AuNPs labels. The sensitivity, simplicity, low cost, easy-to-use mode, and miniaturization/portability of the electrochemical detection system make it ideal for point-of-care applications.

  • Oceans acidifying at unprecedented speed, at least over the past 300 million years (2012)

    Pelejero Bou, Carles (CSIC - ICM)

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    Oceans acidifying at unprecedented speed, at least over the past 300 million years

    In addition to causing global warming, anthropogenic emissions of CO2 are altering the chemistry of Earth's oceans, turning them more acidic. This change has important implications for marine organisms and ecosystems. Important insights on this have been obtained from laboratory experiments, in which marine organisms are exposed to future levels of ocean pH. This experimental approach, however, is limited by their reduced ecologic complexity compared to the real world and by the duration of the experiments. Crucial issues such as the possibility of acclimation or evolutionary adaptation of marine organisms is hard to be assessed from this perspective. In this context, a valuable complementary approach consists in scrutinizing the geological record, which contains signatures for a variety of global environmental perturbations, including ocean acidification, plus their associated biotic responses. In this study, we review the record of the past ~300 million years of Earth's history, which contain events that exhibit evidence for elevated atmospheric CO2, global warming, ocean acidification and deoxygenation, some of them with contemporaneous extinction or evolutionary turnover among marine calcifiers. An important event within this period of time is the so-called Paleocene-Eocene thermal Maximum, 56 million years ago, an event characterized by global warming, which caused ocean acidification and extinction of marine biota, mostly from the deep ocean. In this case, estimations indicate that, even though the amounts of carbon released into the system are of a magnitude similar to the current human perturbation, the injection of carbon then was at least 10 times slower than the current one. Further back in time, other major shocks include the asteroid impact at the end of the Cretaceous, 65 million years ago which, in addition to other major environmental changes, also involved a rapid acidification of the oceans. Other extinction events, such as the Permo-Triassic, 200 million years ago, and the end-Permian, 252 million years ago, could have also involved significant acidification. However, all these extinctions were also associated with decreases in the oxygen content of the oceans and major warming. In fact, these are the three main environmental pressures that are currently affecting in a more global way global oceans: warming, acidification and deoxygenation. Although similarities exist with past events in the geological record, our study concludes that, at least over the last 300 million years, none of the change

  • Sequencing of pig genomes (2012)

    Pérez Enciso, Miguel (UAB)

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    Sequencing of pig genomes

    Analyses of pig genomes provide insight into porcine demography and evolution: For 10,000 years pigs and humans have shared a close and complex relationship. From domestication to modern breeding practices, humans have shaped the genomes of domestic pigs. Here we present the assembly and analysis of the genome sequence of a female domestic Duroc pig (Sus scrofa) and a comparison with the genomes of wild and domestic pigs from Europe and Asia. Wild pigs emerged in South East Asia and subsequently spread across Eurasia. Our results reveal a deep phylogenetic split between European and Asian wild boars ~1 million years ago, and a selective sweep analysis indicates selection on genes involved in RNA processing and regulation. Genes associated with immune response and olfaction exhibit fast evolution. Pigs have the largest repertoire of functional olfactory receptor genes, reflecting the importance of smell in this scavenging animal. The pig genome sequence provides an important resource for further improvements of this important livestock species, and our identification of many putative disease-causing variants extends the potential of the pig as a biomedical model.