11,836 research outputs found

    Factors Affecting Biodiversity Protection in the Mediterranean Basin

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    Earth’s biodiversity includes all extant species; however, species are not evenly distributed across the planet. Species tend to be clustered in densely populated areas known as “biodiversity hotspots;” species which inhabit only a single area are also termed “endemic,” and tend to be highly vulnerable to population-reducing changes in their environment. Biodiversity hotspots are considered priorities for conservation if the area has a high rate of endemism as well as a notable and continual habitat loss (Noss et al., 2015). Preventing biodiversity loss is a complex and multi-level decision-making process about setting priorities and defining clear biodiversity protection areas. Biodiversity loss, or the loss of entire species or sub-populations in an area, can be driven by multiple processes, including land use changes, climate change, and the introduction of invasive species (Plexida et al. 2018). The Mediterranean Basin is one such hotspot, transecting multiple countries surrounding the Mediterranean Sea, including European, Middle Eastern, and North African countries with different systems of government and cultural perceptions of environmental resources and biodiversity. Furthermore, the basin is one the most species-rich biodiversity hotspots on Earth in terms of endemic vascular plants and has high rates of endemism for amphibians and fish, as well as being an important migration corridor for many bird species (Cuttelod et al., 2008). The hotspot is at high risk for continued biodiversity loss due to 53 several human-driven factors including population increase and government-level environmental policies (Grainger, 2003)

    Festes d'infants

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    Intravitreal anti-VEGF agents and cardiovascular risk

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    Universal conductivity and dimensional crossover in multi-layer graphene

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    We show, by exact Renormalization Group methods, that in multi-layer graphene the dimensional crossover energy scale is decreased by the intra-layer interaction, and that for temperatures and frequencies greater than such scale the conductivity is close to the one of a stack of independent layers up to small corrections

    Defect turbulence in inclined layer convection

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    We report experimental results on the defect turbulent state of undulation chaos in inclined layer convection of a fluid withPrandtl number ≈1\approx 1. By measuring defect density and undulation wavenumber, we find that the onset of undulation chaos coincides with the theoretically predicted onset for stable, stationary undulations. At stronger driving, we observe a competition between ordered undulations and undulation chaos, suggesting bistability between a fixed-point attractor and spatiotemporal chaos. In the defect turbulent regime, we measured the defect creation, annihilation, entering, leaving, and rates. We show that entering and leaving rates through boundaries must be considered in order to describe the observed statistics. We derive a universal probability distribution function which agrees with the experimental findings.Comment: 4 pages, 5 figure

    Reinforcement Learning for Agents with Many Sensors and Actuators Acting in Categorizable Environments

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    In this paper, we confront the problem of applying reinforcement learning to agents that perceive the environment through many sensors and that can perform parallel actions using many actuators as is the case in complex autonomous robots. We argue that reinforcement learning can only be successfully applied to this case if strong assumptions are made on the characteristics of the environment in which the learning is performed, so that the relevant sensor readings and motor commands can be readily identified. The introduction of such assumptions leads to strongly-biased learning systems that can eventually lose the generality of traditional reinforcement-learning algorithms. In this line, we observe that, in realistic situations, the reward received by the robot depends only on a reduced subset of all the executed actions and that only a reduced subset of the sensor inputs (possibly different in each situation and for each action) are relevant to predict the reward. We formalize this property in the so called 'categorizability assumption' and we present an algorithm that takes advantage of the categorizability of the environment, allowing a decrease in the learning time with respect to existing reinforcement-learning algorithms. Results of the application of the algorithm to a couple of simulated realistic-robotic problems (landmark-based navigation and the six-legged robot gait generation) are reported to validate our approach and to compare it to existing flat and generalization-based reinforcement-learning approaches

    Introduction : solidarities in motion : hybridity and change in migrant support practices

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    The so-called ‘Eurozone’ and ‘migration’ crises mark critical moments in Europe’s recent political history and share similarities to the extent that they both have increased political conflict, mobilised large parts of civil society, and put renewed attention upon the notion of ‘solidarity’. Focusing on the specific case of solidarity with migrants, this articles argues that times of crises have increasingly blurred the lines between contentious and non-contentious forms of civil society engagement. Scrutinising these dynamics of hybridisation, we bridge diverse, yet largely disconnected literatures, including social movement, civil society and humanitarian studies. In particular, we suggest that the disciplinary and analytical distinction between volunteering and non-profit activities on the one hand and social movements and political activism on the other is too rigid and does obscure parts of a complex phenomenon, which is characterised by activities that often intersect between humanitarian practices and contentious politics

    Linking urban design to sustainability : formal indicators of social urban sustainability field research in Perth, Western Australia

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    The making of a livable urban community is a complex endeavor. For much of the 20th Century plannersand engineers believed that modern and rational decision-making would create successful cities. Today, political leaders across the globe are considering ways to promote sustainable development and the concepts of New Urbanism are making their way from the drawing board to the ground. While much has changed in the world, the creation of a successful street is as much of an art today as it was in the 1960s.Our work seeks to investigate 'street life' in cities as a crucial factor towards community success. What arethe components of the neighborhood and street form that contributes to the richness of street life? To answer this question we rely on the literature. The aim of the Formal Indicators of Social Urban Sustainability studyis to measure the formal components of a neighborhood and street that theorists have stated important in promoting sustainability. This paper will describe how this concept helps to bridge urban design and sustainability. It will describe the tool and show how this was applied in a comparative assessment of Joondalup and Fremantle, two urban centers in the Perth metropolitan area

    Legal determinants of external finance revisited : the inverse relationship between investor protection and societal well-being

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    This paper investigates relationships between corporate governance traditions and quality of life as measured by a number of widely reported indicators. It provides an empirical analysis of indicators of societal health in developed economies using a classification based on legal traditions. Arguably the most widely cited work in the corporate governance literature has been the collection of papers by La Porta et al. which has shown, inter alia, statistically significant relationships between legal traditions and various proxies for investor protection. We show statistically significant relationships between legal traditions and various proxies for societal health. Our comparative evidence suggests that the interests of investors may not be congruent with the interests of wider society, and that the criteria for judging the effectiveness of approaches to corporate governance should not be restricted to financial metrics

    Weak Riemannian manifolds from finite index subfactors

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    Let N⊂MN\subset M be a finite Jones' index inclusion of II1_1 factors, and denote by UN⊂UMU_N\subset U_M their unitary groups. In this paper we study the homogeneous space UM/UNU_M/U_N, which is a (infinite dimensional) differentiable manifold, diffeomorphic to the orbit O(p)={upu∗:u∈UM} {\cal O}(p) =\{u p u^*: u\in U_M\} of the Jones projection pp of the inclusion. We endow O(p){\cal O}(p) with a Riemannian metric, by means of the trace on each tangent space. These are pre-Hilbert spaces (the tangent spaces are not complete), therefore O(p){\cal O}(p) is a weak Riemannian manifold. We show that O(p){\cal O}(p) enjoys certain properties similar to classic Hilbert-Riemann manifolds. Among them, metric completeness of the geodesic distance, uniqueness of geodesics of the Levi-Civita connection as minimal curves, and partial results on the existence of minimal geodesics. For instance, around each point p1p_1 of O(p){\cal O}(p), there is a ball {q∈O(p):∄q−p1∄<r}\{q\in {\cal O}(p):\|q-p_1\|<r\} (of uniform radius rr) of the usual norm of MM, such that any point p2p_2 in the ball is joined to p1p_1 by a unique geodesic, which is shorter than any other piecewise smooth curve lying inside this ball. We also give an intrinsic (algebraic) characterization of the directions of degeneracy of the submanifold inclusion O(p)⊂P(M1){\cal O}(p)\subset {\cal P}(M_1), where the last set denotes the Grassmann manifold of the von Neumann algebra generated by MM and pp.Comment: 19 page
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