Aguirre J.,CSIC - National Institute of Aerospace Technology |
Papo D.,Technical University of Madrid |
Buldu J.M.,Technical University of Madrid |
Buldu J.M.,Complex Systems Group
Nature Physics | Year: 2013
Competitive interactions represent one of the driving forces behind evolution and natural selection in biological and sociological systems. For example, animals in an ecosystem may vie for food or mates; in a market economy, firms may compete over the same group of customers; sensory stimuli may compete for limited neural resources to enter the focus of attention. Here, we derive rules based on the spectral properties of the network governing the competitive interactions between groups of agents organized in networks. In the scenario studied here the winner of the competition, and the time needed to prevail, essentially depend on the way a given network connects to its competitors and on its internal structure. Our results allow assessment of the extent to which real networks optimize the outcome of their interaction, but also provide strategies through which competing networks can improve on their situation. The proposed approach is applicable to a wide range of systems that can be modelled as networks. Copyright © 2013 Macmillan Publishers Limited. All rights reserved.
Ruiz-Mirazo K.,University of the Basque Country |
Briones C.,CSIC - National Institute of Aerospace Technology |
De La Escosura A.,Autonomous University of Madrid
Chemical Reviews | Year: 2014
In order to explain how the first organisms might have appeared on Earth, or elsewhere, it is necessary to develop chemistries that enable the synthesis of information-bearing polymers, protometabolic networks, and protocellular compartments under compatible prebiotic conditions. In this direction, the first step would be the synthesis of the monomeric units that constitute peptides, nucleic acids or their analogue polymers, and vesicle membranes. Some of these building blocks could have been delivered to Earth from extraterrestrial sources, while their endogenous synthesis on our planet is another feasible option. Catalysis, in particular organocatalysis and organometallic catalysis, could have enlarged and diversified the set of compounds potentially present in different prebiotic scenarios. Vesicles composed of mixtures of simple amphiphilic molecules and surfactants, on the other hand, have shown the required stability and permeability for encapsulation of nucleic acids and peptides.
Alves J.,University of Vienna |
Bouy H.,CSIC - National Institute of Aerospace Technology
Astronomy and Astrophysics | Year: 2012
Aims. The aim of this work is to characterize the stellar population between Earth and the Orion A molecular cloud where the well-known star formation benchmark Orion nebula cluster (ONC) is embedded. Methods. We used the denser regions the Orion A cloud to block optical background light, effectively isolating the stellar population in front of it. We then used a multi-wavelength observational approach to characterize the cloud's foreground stellar population. Results. We find that there is a rich stellar population in front of the Orion A cloud, from B-stars to M-stars, with a distinct 1) spatial distribution; 2) luminosity function; and 3) velocity dispersion from the reddened population inside the Orion A cloud. The spatial distribution of this population peaks strongly around NGC 1980 (iota Ori) and is, in all likelihood, the extended stellar content of this poorly studied cluster. We infer an age of ∼4-5 Myr for NGC 1980 and estimate a cluster population of about 2000 stars, which makes it one of the most massive clusters in the entire Orion complex. This newly found population overlaps significantly with what is currently assumed to be the ONC and the L1641N populations, and can make up for more than 10-20% of the ONC population (30-60% if the Trapezium cluster is excluded from consideration). What is currently taken in the literature as the ONC is then a mix of several intrinsically different populations, namely 1) the youngest population, including the Trapezium cluster and ongoing star formation in the dense gas inside the nebula; 2) the foreground population, dominated by the NGC 1980 cluster; and 3) the poorly constrained population of foreground and background Galactic field stars. Conclusions. Our results support a scenario where the ONC and L1641N are not directly associated with NGC 1980, i.e., they are not the same population emerging from its parental cloud, but are instead distinct overlapping populations. The nearest massive star formation region and the template for massive star-and cluster formation models is then substantially contaminated by the foreground stellar population of the massive NGC 1980 cluster, formed about 4-5 Myr ago in a different, but perhaps related, event in the larger Orion star formation complex. This result calls for a revision of most of the observables in the benchmark ONC region (e.g., ages, age spread, cluster size, mass function, disk frequency, etc.). © 2012 ESO.
Munoz Caro G.M.,CSIC - National Institute of Aerospace Technology |
Dartois E.,CNRS Paris Institute of Astrophysics
Chemical Society Reviews | Year: 2013
A compendium of different solid carbonaceous materials detected in space is presented, focussing on the search for organic matter of prebiotic interest. This journey takes us from the carbon grains likely formed in the atmospheres of evolved stars to organic grain mantles made from ice processing thought to be present in dense interstellar clouds and circumstellar regions, making a stop in solar system objects that could have delivered organic species to the early Earth. The most abundant carbon materials detected to date in space appear to be of little biological relevance. On the other hand, organic refractory residues, made in the laboratory from UV-photoprocessing followed by warm-up of interstellar ice analogs, are a hydrocarbon material rich in O and N containing chemical compounds that could act as initiators of prebiotic chemistry. A similar material might be present in dust grains inside dense clouds or circumstellar regions, some comets, and as a minor component in carbonaceous chondrites. We use infrared spectroscopy as a tool to spot organic refractory matter in various space environments. The delivery of organic materials via comets, (micro-) meteorites, and interplanetary dust particles to the primitive Earth might have contributed as a starting material for prebiotic chemistry. To test this hypothesis, it is first essential to characterize the composition of exogenous organic matter. This journal is © The Royal Society of Chemistry.
Mendez J.,CSIC - Institute of Materials Science |
Lopez M.F.,CSIC - Institute of Materials Science |
Martin-Gago J.A.,CSIC - Institute of Materials Science |
Martin-Gago J.A.,CSIC - National Institute of Aerospace Technology
Chemical Society Reviews | Year: 2011
Creating or connecting together large organic molecules, as polycyclic aromatic hydrocarbons (PAH), by chemical reactions readily on surfaces is the first step to a true advance in the field of molecular electronics. On-surface synthesis can be regarded as an efficient means to build new molecular species by using bottom-up strategies. Recently, a collection of different reactions leading to large tailor-made organic molecules on single-crystal metal surfaces has been reported. The fundamental mechanisms controlling these reactions can be investigated from a surface science perspective. This discipline skillfully combines the use of characterization techniques at the nanoscale, with single-crystal metallic surfaces able to catalyse these reactions. We present a tutorial review that highlights the relevance of the new bottom up strategies and classifies most of the different molecular on-surface reactions involving aromatic organic molecules that have been published up to date. © 2011 The Royal Society of Chemistry.
Cernicharo J.,CSIC - National Institute of Aerospace Technology
EAS Publications Series | Year: 2012
The interpretation of molecular line surveys at millimetre and submillimetre wavelengths towards astrophysical objects requires a good knowledge of the spectroscopy of the molecules present in the gas phase, and of the basic collisional processes between them and molecular and atomic Hydrogen, Helium, and electrons. From the chemical point of view, the modeling of these data requires a large amount of laboratory information concerning the reactivity of these species in the gas phase and in the ice mantles of dust grains. In this contribution I will focus on the problems to interpret line surveys and I will discuss how we will have to proceed in the new era opened by ALMA where sensitivity and angular resolution will surpass by nearly a factor 10 those of existing facilities, and where the spectral confusion limit could be reached towards many sources. © The Author(s) 2013.
Javier Alvaro J.,CSIC - National Institute of Aerospace Technology
Basin Research | Year: 2013
The syn-rift/post-rift transition of the late Ediacaran-mid Cambrian Atlas rift is characterized by the interplay of several processes, such as a widespread episode of fracturing and tilting, associated with encasement of fault-controlled vein metallic ore deposits of economic importance, and carbonate production and phosphogenesis (Taguedit Bed, Tabia Member) bordering rift-flank uplifts. A correlatable unconformity marks the end of these processes and the beginning of a thermal subsidence-dominated regime with development of a more stable, carbonate, peritidal-dominated platform (Tifnout Member). Late Ediacaran microbial carbonate production and phosphogenesis extended in discontinuous belts around the periphery of uplifted rift shoulders and flanks. Karst development is interpreted to have formed along synsedimentary faults and fractures during abrupt tectonic uplift associated with emplacement of polymetallic hydrothermal dikes (rich in Cu, Fe and subsidiary Pb, Zn). Isotopic analysis indicates that speleothem precipitation in karstic palaeocaves displays significantly lighter δ13C and δ18O values as compared to the host dolomite, implying calcite precipitation by terrestrial fluids rich in decomposing organic matter and/or microbial activity in the cave system. © 2012 The Authors. Basin Research © 2012 Blackwell Publishing Ltd, European Association of Geoscientists & Engineers and International Association of Sedimentologists.
Crusats J.,University of Barcelona |
El-Hachemi Z.,CSIC - National Institute of Aerospace Technology |
Ribo J.M.,University of Barcelona
Chemical Society Reviews | Year: 2010
There are few unambiguous reports describing the transfer of chirality from stirring vortices down to the level of electronic transitions. In this tutorial review the methods reported are discussed as well as the structural trends that seem to be necessary conditions in order to detect this phenomenon. © 2010 The Royal Society of Chemistry.
Gonzalez-Pastor J.E.,CSIC - National Institute of Aerospace Technology
FEMS Microbiology Reviews | Year: 2011
A social behavior named cannibalism has been described during the early stages of sporulation of the Gram-positive Bacillus subtilis. This phenomenon is based on the heterogeneity of sporulating populations, constituted by at least two cell types: (1) sporulating cells, in which the master regulator of sporulation Spo0A is active, and (2) nonsporulating cells, in which Spo0A is inactive. Sporulating cells produce two toxins that act cooperatively to kill the nonsporulating sister cells. The nutrients released by the dead cells into the starved medium are used for growth by the sporulating cells that are not yet fully committed to sporulate, and as a result, sporulation is arrested. This review outlines the molecular mechanisms of the killing and immunity to the toxins, the regulation of their production and other examples of killing of siblings in microorganisms. The biological significance of this behavior is discussed. © 2010 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd.
Menor-Salvan C.,CSIC - National Institute of Aerospace Technology |
Marin-Yaseli M.R.,CSIC - National Institute of Aerospace Technology
Chemical Society Reviews | Year: 2012
A crystalline ice matrix at subzero temperatures can maintain a liquid phase where organic solutes and salts concentrate to form eutectic solutions. This concentration effect converts the confined reactant solutions in the ice matrix, sometimes making condensation and polymerisation reactions occur more favourably. These reactions occur at significantly high rates from a prebiotic chemistry standpoint, and the labile products can be protected from degradation. The experimental study of the synthesis of nitrogen heterocycles at the ice-water system showed the efficiency of this scenario and could explain the origin of nucleobases in the inner Solar System bodies, including meteorites and extra-terrestrial ices, and on the early Earth. The same conditions can also favour the condensation of monomers to form ribonucleic acid and peptides. Together with the synthesis of these monomers, the ice world (i.e., the chemical evolution in the range between the freezing point of water and the limit of stability of liquid brines, 273 to 210 K) is an under-explored experimental model in prebiotic chemistry. © 2012 The Royal Society of Chemistry.