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

  • Marine bacteria are sensitive to human-induced ocean acidification (2016)

    Pelejero Bou, Carles (CSIC - ICM)

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    Marine bacteria are sensitive to human-induced ocean acidification

    In addition to causing global warming, anthropogenic emissions of CO2 are altering the chemistry of Earth’s seas and oceans, turning them more acidic. This change has important implications for many organisms, especially those whose shells or skeletons are made of calcium carbonate, like corals and shellfish. Strong efforts have been devoted to study the potential effects of acidification on these particular species demonstrating, in the majority of occasions, detrimental effects. However, acidification may also interfere with the development of marine bacteria (Fig. 1), which play a crucial role in the global cycle of elements necessary to life. Bacteria act as the primary degraders of organic material produced through photosynthesis of microscopic algae in the ocean, or material released through wastewater. When algae or other organisms die and are degraded by bacteria, at the same time bacteria mediate the release of elements like nitrogen or phosphorous that are essential to the food chain. Thus, bacteria in the sea play a critical role in determining the health of marine ecosystems. In addition, bacteria synthesize vitamins on which algae and other organisms in the sea depend. Despite these important roles, possible ocean acidification effects on marine bacteria have mostly been ignored or neglected. In order to tackle this issue, we performed a metatranscriptome analyses of a phytoplankton bloom mesocosm experiment conducted at Institut de Ciències del Mar with water from the Blanes Bay, north of Barcelona (Fig. 2). Our results demonstrated that marine bacteria exposed to acidification are indeed forced to significantly alter their metabolism. In particular, they respond to low pH by enhancing the expression of genes encoding proton pumps, such as respiration complexes, proteorhodopsin and membrane transporters. Thus, bacteria need to invest extra energy for activating mechanisms to counterbalance the stress produced by acidification. This study, conducted by researchers from Catalonia, Spain and Sweden, suggests that bacterioplankton adaptation to ocean acidification could have long-term effects on the energy balance of ocean ecosystems.

  • Local environmental knowledge enhances human adaptive capacity (2016)

    Reyes García, Victoria (UAB)

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    Local environmental knowledge enhances human adaptive capacity

    Local environmental knowledge refers to the knowledge of natural resources and ecosystems and the associated management practices, beliefs, and institutions, developed by societies with long histories of interactions with particular environments. This ERC-funded research aimed to assess whether, across societies and domains of knowledge, people with more local environmental knowledge enjoy better livelihoods than people with less local environmental knowledge. Specifically, we aimed to explore the benefits that knowledge related to hunting and plants medicinal properties conferred to individuals in three indigenous societies, the Baka (Congo Basin), the Punan (Borneo), and the Tsimane’ (Amazonia).

    Overall, we found that people with more hunting knowledge obtained higher hunting yields than peoples with less hunting knowledge, and that people with more medicinal plant knowledge were sick less often than respondents with less medicinal plant knowledge. Our data, however, did not support the hypotheses that people with more hunting and/or medicinal plant knowledge have better nutritional status than other respondents in the same society. The paradoxical finding that local environmental knowledge provides some individual benefits related to their ability to obtain food and prevent sickness but –overall- does not contribute to better nutrition could potentially be explained through the prevalence of sharing and cooperation. Sharing and cooperation allow resources (i.e., bushmeat) and information (i.e., where to find a medicinal plant) to flow from the more knowledgeable or skilful to the rest of the group, thus potentially contributing to group-level improvements in nutritional status. Our study points to the idea that local knowledge systems might enhance adaptation by first boosting individual ability to obtain food and protect health and then establishing the mechanisms so that these benefits are shared across the various members of the group.

  • Understanding Spin Hall Effect in Dirac Matter (2016)

    Roche, Stephan (ICN2)
    Valenzuela, Sergio O. (ICN2)

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    Understanding Spin Hall Effect in Dirac Matter

    Spin is a fundamental quantum property of particles which behaves similarly to a permanent magnet attached to the quantum object and takes two values + or - half the Planck constant. Spin Hall effect (SHE) is a fundamental mechanism occurring in strong spin-orbit materials and which manifests as an accumulation of up and down spins at the opposite edges of a sample, upon the application of an electrical field. SHE actually converts charge to pure spin current in the direction perpendicular to the charge flow. The great challenge for developing spin-based information-processing technologies requires optimizing the spin Hall angle which measures the strength of SHE. The further use of graphene and other two-dimensional materials has sparked great expectations for the design of innovative heterostructures of superior spintronic performances which could be used in improving STT-MRAM (spin transfer-torque magnetic random access memories) technologies or engineering new spin logic architectures.

    Large values of SHE have been recently reported in graphene decorated with adatoms but those experiments have raised a considerable debate, given the complexity of the underlying phenomenon and multiplicity of parasitic background effects. In collaboration with researchers in the USA and France, we have performed the first fully quantum simulation of the fundamental characteristics of SHE able to revisit these controversial experimental results. We have succeeded in computing the spin Hall angle in large scale disordered forms of chemically functionalized graphene and have analysed how such quantity scales with the density of chemical defects, their spatial distribution and segregation, temperature and device geometry effects.

    Our results suggest substantial capability of graphene for generating large SHE signals provided an atomic-scale control of chemical modification of graphene is achieved, whereas new device geometry has been proposed to reduce parasitic effects and quantitatively size the maximum charge to current conversion efficiency of such two-dimensional materials.

     

  • European seasonal mortality and influenza incidence due to winter temperature variability (2016)

    Rodó i López, Xavier (IC3)

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    European seasonal mortality and influenza incidence due to winter temperature variability

    Adaptation measures taken by different countries to adapt to climate change have resulted in different levels of vulnerability of their population to air temperatures. This is one of the new results of a study led by scientists at the Catalan Institute of Climate Sciences (IC3), and the Universities of Monpetller and Geneva.

    The study also shows that extreme winters are not directly related to seasonal mortality increases nor to flu rises, in countries like the United Kingdom, Belgium and the Netherlands. Conversely, all other countries show different levels of response as a function of the season’s severity. Another interesting result describes the role of low temperatures on mortality rates in the European population, with other factors influencing winter mortality, like hypothermia, hypertension, thrombosis, pneumonia and flu. Not surprisingly, Mediterranean countries are those more vulnerable to low temperatures, with Portugal, Spain and Italy being 7, 4 and 3 times more sensitive to winter temperatures than central Europe countries.

    The study was performed on more than 160 regions, belonging to 16 countries in western Europe, representing more than 400 million people. These new results therefore highlight the key role played by adaptation measures to environmental temperatures. Similarly the variety in the degree of vulnerability to low temperatures can serve to better identify which measures would be more effective to counterbalance the effects exerted by climate change and help mitigate the associate burden in terms of morbidity and mortality.

  • Neurons find order in the noise (2016)

    Sánchez-Vives, María Victoria (FRCB-IDIBAPS)

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    Neurons find order in the noise

     

    High temporal precision sometimes emerges from noisy systems. This is often the case in recurrent networks of dynamic elements (from ionic channels to genes or lasers) that can exhibit emergent collective oscillations of substantial regularity even when the individual elements are considerably noisy. This phenomenon is called stochastic coherence and it can be observed in a large number of systems, for example, in dynamics of global climate. However, how noise-induced dynamics at the local level coexists with regular oscillations at the global level is still unclear. Here we studied the slow oscillation regime exhibited by the cerebral cortex network. Slow oscillations constitute a cortical state consisting of periods of activity or neuronal firing that are interspersed with periods of neuronal silence that alternate at a frequency of around 1 Hz (see Figure). Slow oscillations emerge from the recurrent interaction between cortical neurons, making them a network phenomenon.

    In a model of the cortical network, we observed that a combination of stochastic recurrence-based initiation with deterministic refractoriness lead to maximum collective coherence for an intermediate noise level, such that noise-induced dynamics at the local level coexisted with regular oscillations at the global level. Computational analysis of a biologically realistic network model revealed that an intermediate level of background noise lead to quasi-regular dynamics. We verified this prediction experimentally in cortical slices subject to varying amounts of extracellular potassium, which modulates neuronal excitability and thus synaptic noise (see Figure insets). For intermediate noise (or extracellular potassium) levels, the regularity of the slow oscillation was maximum. Furthermore, there was not only a maximum temporal but also spatial regularity. Taken together, these results allow us to construe the high regularity observed experimentally in the brain as an instance of collective stochastic coherence.

     

     

     

  • The hidden geometry of international trade (2016)

    Serrano, M. Ángeles (UB)

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    The hidden geometry of international trade

    International trade moves billions of euros annually and is one of the key mechanisms in the process of globalization. Its representation as a network of nodes and connections, where nodes are countries and the connections between them correspond to import and export relationships, reveals a complex architecture characterized by typical features of complex networks in different domains. Although the famous gravity model of trade reproduces flows well, it is unable to predict the existence of connections and, therefore, to explain the complex structure of the international trade network

    In our work, we combine economic size and the different dimensions that affect distance in international trade beyond mere geography to produce the World Trade Atlas 1870-2013 (http://morfeo.ffn.ub.edu/wta1870-2013/), a collection of annual world trade maps. Trade distances in these maps, based on a gravity model predicting the existence of significant trade channels, are such that the closer countries are in the hyperbolic trade space, the greater their chance of becoming connected. The atlas provides us with information regarding the long-term evolution of the international trade system and demonstrates that, in terms of trade, the world is not flat but hyperbolic, as a reflection of its complex architecture. The departure from flatness has been increasing since World War I, meaning that differences in trade distances are growing and trade networks are becoming more hierarchical. Smaller-scale economies are moving away from other countries except for the largest economies; meanwhile those large economies are increasing their chances of becoming connected worldwide. At the same time, Preferential Trade Agreements do not fit in perfectly with natural communities within the trade space and have not necessarily reduced internal trade barriers. We discuss an interpretation in terms of globalization, hierarchization, and localization; three simultaneous forces that shape the international trade system.

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