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.


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  • Holography, Cosmological Phase Transitions and Gravitational Waves (2021)

    Mateos, David (UB)

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    Holography, Cosmological Phase Transitions and Gravitational Waves

    Phase transitions are ubiquitous in Nature. When we boil liquid water, bubbles of vapour appear and expand until the entire volume is filled by gas. It is conjectured that the Universe may have undergone a similar process many billions of year ago: As it expanded and cooled down, bubbles of a new phase may have appeared and expanded until the new phase filled the entire Universe. 

    This process, known as a cosmological phase transition, would have produced tiny ripples in the fabric of spacetime, known as Gravitational Waves, that would have been traveling through the Universe ever since they were emitted. The most exciting aspect is that we may be able to detect them in the near future. 

    Maximising the discovery potential requires the determination of a few parameters controlling the phase transition. The most important one is the bubble wall velocity, namely the velocity at which the bubbles of the new phase expand. This parameter is extremely challenging to compute with conventional methods because it involves out-of-equilibrium physics. For this reason, we have used a string-theoretical tool known as "holography", which maps the properties of the bubbles in our four-dimensional world to those of … a black hole in five dimensions! 

    By solving Einstein's equations in five dimensions we have determined the time evolution of the black hole horizon, and from this the wall velocity. We have been able to go even further and we are currently computing the spectrum of four-dimensional Gravitational Waves directly in terms of the five-dimensional black hole dynamics. 

  • Advanced nanobiosensors for diagnostics of COVID19 and more (2021)

    Merkoçi, Arben (ICN2)

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    Advanced nanobiosensors for diagnostics of COVID19 and more

    Nanobiosensors represent the next generation of biosensors that has emerged in the last two decades thanks to the contribution from new nanotechnologies and nanomaterials.  One of the urgent application of nanobiosensors is related to the diagnostics in various clinical scenarios of COVID19 pandemics for which we have shown the recent advanced of these devices, the raised issues and the work requested to implement them in the clinical practice. [1] We also reported an electrochemical aptamer-based (EAB) sensor for the rapid and efficient detection of the SARS-CoV-2 spike protein. The clinical potential of the sensor, was demonstrated in biological fluids (serum and artificial saliva) allowing for rapid (minutes) and single-step detection of the S protein in its clinical range. [2]

    The broad range of nanomaterials with interesting optical or electrical properties and nanotechnologies is allowing breakthrough achievements in the field of nanobiosensors reaching extremely low detection limits (attomolar levels). [3] Nanobiosensors are also expected to contribute as smart devices in food and agriculture areas thanks also to their combination with artificial intelligence and machine learning tools as discussed in our recent invited news & views article at Nature Food. [4]

  • Relationship between chromosomal instability and senescence revealed in the fly Drosophila (2021)

    Milán Kalbfleisch, Marco (IRB Barcelona)

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    Relationship between chromosomal instability and senescence revealed in the fly Drosophila

    Chromosomal instability (CIN), the continuous change in chromosome number and structure, is a feature of most solid tumours. Likewise, cellular senescence is a process that is highly related to cellular ageing and its link to cancer is becoming increasingly clear. The work carried out by Jery Joy and colleagues in the laboratory of Marco Milán has utilized Drosophila as model system to show that in an epithelial tissue with high levels of CIN those cells with an altered balance of chromosome number detach from their neighbouring cells and enter senescence. Senescent cells are characterised by a permanently halted cell cycle and by the secretion of a large number of proteins. This abnormal secretion of proteins alters the surrounding tissue, alerting the immune system and causing inflammation. Cells with an unbalanced number of chromosomes present high levels of proteotoxic stress, accumulate aberrant mitochondria and, therefore, a high level of oxidative stress, which in turn activates the  c-Jun N-terminal kinase (JNK) signalling pathway, triggering entry into senescence. Interestingly, removing dysfunctional mitochondria or reducing proteotoxic stress by different means rescue the deleterious effects of CIN. These findings open new avenues of research to find therapeutic targets and reduce senescence levels caused by chromosomal instability in solid tumours.

  • Mapping the dark matter in the Universe     (2021)

    Miquel Pascual, Ramon (IFAE)

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    Mapping the dark matter in the Universe    

    There is overwhelming evidence that most of the matter in the Universe is in a "dark" form that neither emits nor blocks light, and is therefore invisible to even the largest telescopes. While the detailed nature of this "dark matter" remains a mystery, its gravitational interactions can be used to detect it and map it. Particularly relevant is the so-called "weak gravitational lensing" effect, in which the observed size, shape and orientation of distant galaxies are slightly distorted by the gravitational pull of the masses between them and us. Then, the statistical properties of a large set of images of distant galaxies can be studied to determine the location of the intervening (mostly dark) matter.

    The Dark Energy Survey (DES) is an international collaboration of 400 scientists from 25 institutions in 7 countries that has surveyed an eighth of the sky using DECam, a 570-megapixel camera installed at the Blanco 4-meter telescope in the Cerro Tololo Inter-American Observatory in Chile. The IFAE group led by Ramon Miquel was responsible for the design and production of most of the read-out electronics for the 74 CCDs in DECam.

    Using half of the final data sample, DES has measured the shapes of over 100 million distant galaxies, and, analyzing their statistical properties, has produced the largest mass map to date (figure). In it, one can observe how regions with more dark matter (yellow) contain numerous visible galaxy clusters (green circles), while regions with less dark matter (black) are also relatively empty of ordinary matter. This analysis was co-led by Marco Gatti, a PhD student at IFAE at the time (now a postdoctoral researcher at the University of Pennsylvania).

    Studying the evolution in cosmic time of the clustering of matter, DES is also able to characterize the nature of the mysterious "dark energy," responsible for the current accelerated expansion of the Universe. The corresponding paper is currently under review in Physical Review D.

  • Coupling Metabolism and Differentiation to treat kidney disease (2021)

    Montserrat Pulido, Núria (IBEC)

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    Coupling Metabolism and Differentiation to treat kidney disease

    Chronic kidney disease affects more than 697 million people around the world. In total, it is estimated that 1.2 million people die each year due to this disease, which represents almost 5% of all annual deaths worldwide. Despite the enormous financial and personal burden that this entails, until now the biological mechanisms behind this condition were unknown, due to the structural and functional complexity of the kidney. 

    This study has uncovered that genes controlling lipid metabolism are switched off when the kidney is chronically damaged. Indeed, the loss of the healthy “signature” in the cells of the proximal tubule is related to estrogen related receptor alpha (ESRRa). To prove on the importance of the role of ESRRa we generated mini-kidneys and showed that when ESRRa was switched back on, the cells of the proximal tubuli of the kidney regain their function. Such observations occurred also in two animal models of chronic kidney damage from our collaborators in the study (University of Pennsylvania).

  • Fossil Apes and Human Evolution (2021)

    Moyà Solà, Salvador (ICP)

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    Fossil Apes and Human Evolution

    Ever since Charles Darwin, the idea that humans originated in Africa from an ape ancestor was hotly debated, but progressively gained support. The British naturalist, however, was unable to determine the kinship between humans and modern hominoid primates (gorillas, chimpanzees, orangutans, and gibbons). Recent molecular studies, however, have determined that humans and chimps share a common ancestor (LCA) that lived during the Upper Miocene, between 9 and 7 million years ago, a fact that is frequently interpreted as evidence that it was chimp-like. This idea has dominated discussions of human ancestry for decades, and consequently, the more primitive Miocene apes were excluded as potential candidates. There are two major points of view in assessing the role of the ape fossil record in our evolutionary history. One rejects the idea that they are relevant in the debate over the origins of humans, while others think they play a crucial role. The fact that today's hominoids are just the survivors of terminal specialized branches of a group that was much larger and more diverse in the past, provides little evidence for the evolutionary history of human ancestors. It is exactly for this reason that the study of Miocene apes is required.


    The inclusion of Miocene apes in the analysis sheds a new perspective on the reconstruction of the LCA of humans and chimps. The fossil record clearly indicates that living hominoids constitute a narrow representation of an ancient radiation of more widely distributed, diverse taxa, none of which exhibits the entire suite of locomotor adaptations present in their extant relatives. Introducing Miocene apes into the equation allows us to understand that some modern ape similarities might have evolved in parallel in response to similar selection pressures. Early hominins originated in Africa from a Miocene LCA that does not match any living ape. Despite phylogenetic uncertainties, fossil apes remain key to reconstructing the "starting point" from which humans and chimps diverged. Future research should focus on fieldwork in new areas and methodological advances in morphology-based phylogenetics and paleoproteomics.