960 research outputs found

    Conservation planning with spatially explicit models : a case for horseshoe bats in complex mountain landscapes

    Get PDF
    This work was partly Funded by the French Ministry of Ecology, Sustainable Development and Energy, France in support of the development of the DEB-MOCHAB project (2013–2015) (Species distribution modelling: a tool for evaluation the conservation of species’ habitats and ecological continuities). This work was also partially supported by the OpenNESS project funded from the European Union’s Seventh Programme for research, technological development and demonstration under grant agreement n° 308428.Context Bats are considered as an ecological indicator of habitat quality due to their sensitivity to human-induced ecosystem changes. Hence, we will focus the study on two indicator species of bats as a proxy to evaluate structure and composition of the landscape to analyze anthropic pressures driving changes in patterns. Objectives This study develops a spatially-explicit model to highlight key habitat nodes and corridors which are integral for maintaining functional landscape connectivity for bat movement. We focus on a complex mountain landscape and two bat species: greater (Rhinolophus ferrumequinum) and lesser (Rhinolophus hipposideros) horseshoe bats which are known to be sensitive to landscape composition and configuration. Methods Species distribution models are used to delineate high-quality foraging habitat for each species using opportunistic ultrasonic bat data. We then performed connectivity analysis combining (modelled) suitable foraging habitat and (known) roost sites. We use graph-theory and the deviation in the probability of connectivity to quantify resilience of the landscape connectivity to perturbations. Results Both species were confined to lowlands (<1000 m elevation) and avoided areas with high road densities. Greater horseshoe bats were more generalist than lesser horseshoe bats which tended to be associated with broadleaved and mixed forests. Conclusions The spatially-explicit models obtained were proven crucial for prioritizing foraging habitats, roost sites and key corridors for conservation. Hence, our results are being used by key stakeholders to help integrate conservation measures into forest management and conservation planning at the regional level. The approach used can be integrated into conservation initiatives elsewhere.PostprintPeer reviewe

    Entanglement of four qubit systems: a geometric atlas with polynomial compass I (the finite world)

    Full text link
    We investigate the geometry of the four qubit systems by means of algebraic geometry and invariant theory, which allows us to interpret certain entangled states as algebraic varieties. More precisely we describe the nullcone, i.e., the set of states annihilated by all invariant polynomials, and also the so called third secant variety, which can be interpreted as the generalization of GHZ-states for more than three qubits. All our geometric descriptions go along with algorithms which allow us to identify any given state in the nullcone or in the third secant variety as a point of one of the 47 varieties described in the paper. These 47 varieties correspond to 47 non-equivalent entanglement patterns, which reduce to 15 different classes if we allow permutations of the qubits.Comment: 48 pages, 7 tables, 13 figures, references and remarks added (v2

    Algebraic invariants of five qubits

    Full text link
    The Hilbert series of the algebra of polynomial invariants of pure states of five qubits is obtained, and the simplest invariants are computed.Comment: 4 pages, revtex. Short discussion of quant-ph/0506073 include

    Ab-initio vibrational properties of transition metal chalcopyrite alloys determined as high-efficiency intermediate-band photovoltaic materials

    Get PDF
    In this work, we present frozen phonon and linear response ab-initio research into the vibrational properties of the CuGaS2 chalcopyrite and transition metal substituted (CuGaS2)M alloys. These systems are potential candidates for developing a novel solar-cell material with enhanced optoelectronic properties based in the implementation of the intermediate-band concept. We have previously carried out ab-initio calculations of the electronic properties of these kinds of chalcopyrite metal alloys showing a narrow transition metal band isolated in the semiconductor band gap. The substitutes used in the present work are the 3d metal elements, Titanium and Chromium. For the theoretical calculations we use standard density functional theory at local density and generalized gradient approximation levels. We found that the optical phonon branches of the transition metal chalcopyrite, are very sensitive to the specific bonding geometry and small changes in the transition metal environment

    The ADAMTS (A Disintegrin and Metalloproteinase with Thrombospondin motifs) family

    Get PDF
    The ADAMTS (A Disintegrin and Metalloproteinase with Thrombospondin motifs) enzymes are secreted, multi-domain matrix-associated zinc metalloendopeptidases that have diverse roles in tissue morphogenesis and patho-physiological remodeling, in inflammation and in vascular biology. The human family includes 19 members that can be sub-grouped on the basis of their known substrates, namely the aggrecanases or proteoglycanases (ADAMTS1, 4, 5, 8, 9, 15 and 20), the procollagen N-propeptidases (ADAMTS2, 3 and 14), the cartilage oligomeric matrix protein-cleaving enzymes (ADAMTS7 and 12), the von-Willebrand Factor proteinase (ADAMTS13) and a group of orphan enzymes (ADAMTS6, 10, 16, 17, 18 and 19). Control of the structure and function of the extracellular matrix (ECM) is a central theme of the biology of the ADAMTS, as exemplified by the actions of the procollagen-N-propeptidases in collagen fibril assembly and of the aggrecanases in the cleavage or modification of ECM proteoglycans. Defects in certain family members give rise to inherited genetic disorders, while the aberrant expression or function of others is associated with arthritis, cancer and cardiovascular disease. In particular, ADAMTS4 and 5 have emerged as therapeutic targets in arthritis. Multiple ADAMTSs from different sub-groupings exert either positive or negative effects on tumorigenesis and metastasis, with both metalloproteinase-dependent and -independent actions known to occur. The basic ADAMTS structure comprises a metalloproteinase catalytic domain and a carboxy-terminal ancillary domain, the latter determining substrate specificity and the localization of the protease and its interaction partners; ancillary domains probably also have independent biological functions. Focusing primarily on the aggrecanases and proteoglycanases, this review provides a perspective on the evolution of the ADAMTS family, their links with developmental and disease mechanisms, and key questions for the future

    Pt/CexPr1−xO2 (x = 1 or 0.9) NOx storage–reduction (NSR) catalysts

    Get PDF
    Model Pt/Ce0.9Pr0.1O2 and Pt/CeO2 NOx storage–reduction catalysts were prepared via nitrate calcination, co-precipitation and carbon-templating routes. Raman spectroscopic data obtained on the catalysts indicated that the introduction of praseodymium into the ceria lattice increased the concentration of defect sites (vacancies), arising from the higher reducibility of the Pr4+ cation compared to Ce4+. For the Pr-promoted samples, H2-TPR profiles contained high temperature bulk reduction peaks which were less pronounced compared with their ceria analogs, indicating that the presence of praseodymium enhances oxygen mobility due to the creation of lattice defects. Under lean-rich cycling conditions, the cycle-averaged NOx conversion of the Pt/Ce0.9Pr0.1O2 samples was in each case substantially higher than that of the Pt/CeO2 analog, amounting to a difference of 10–15% in the absolute NOx conversion in some cases. According to DRIFTS data, a double role can be assigned to Pr doping; on the one hand, Pr accelerates the oxidation of adsorbed NOx species during the lean periods. On the other hand, Pr doping destabilizes the adsorbed NOx species during the rich periods, and the kinetics of nitrate decomposition are faster on Pt/Ce0.9Pr0.1O2, leading to improved catalyst regeneration. These results suggest that ceria-based mixed oxides incorporating Pr are promising materials for NOx storage–reduction catalysts intended for low temperature operation.The financial support of Generalitat Valenciana (predoctoral stay BEFPI/2012), the Spanish Ministry of Economy and Competitiveness (Project CTQ2012-30703), and co-financing by FEDER resources is acknowledged. Partial financial support was also provided by the National Science Foundation and the U.S. Department of Energy (DOE) under award no. CBET-1258742

    Learned predictiveness influences rapid attentional capture:Evidence From the Dot Probe Task

    Get PDF
    Attentional theories of associative learning and categorization propose that learning about the predictiveness of a stimulus influences the amount of attention that is paid to that stimulus. Three experiments tested this idea by looking at the extent to which stimuli that had previously been experienced as predictive or nonpredictive in a categorization task were able to capture attention in a dot probe task. Consistent with certain attentional theories of learning, responses to the dot probe were faster when it appeared in a location cued by a predictive stimulus compared to a location cued by a nonpredictive stimulus. This result was obtained only with short (250-ms or 350-ms) but not long (1,000-ms) delays between onset of the stimuli and the dot probe, suggesting that the observed spatial cuing effect reflects the operation of a relatively rapid, automatic process. These findings are consistent with the approach to the relationship between attention and learning taken by the class of models exemplified by Mackintosh's (1975) theory.</p

    The effect of experience and instructions on learned attentional biases

    Get PDF
    Afiliaciones: Instituto de Investigación Biomédica de Málaga (IBIMA), University of Malaga, Spain Primary Care and Public Health Sciences, King’s College London, UK School of Psychology, UNSW Australia, Sydney, AustraliaIt has been shown that selective attention is allocated to the best available predictor of an outcome, which is known as learned predictiveness. Mitchell et al. (2012) have shown that instructions about the ‘relevance’ of each stimulus can influence (and even reverse) the learned predictiveness attentional bias, suggesting that propositional reasoning plays a crucial role in this phenomenon. Our experiment further explores the effects of instructions on this learned attentional bias. As a difference with previous work, we measured attentional capture through spatial cueing effects, which have been found to rely on rapid attentional processes (Le Pelley et al., 2013). Participants responded faster to events presented in the spatial location cued by stimuli that had previously been trained as predictive through trial-by-trial learning. However, verbal instructions regarding relevance failed to speed up participants’ responses or to modulate the effect of learned predictiveness on spatial cueing. These results suggest that predictive stimuli produce an attentional bias which is not (always) under voluntary control.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
    corecore