5,778 research outputs found

    Etnički sukob kao unutar-grupna pojava: preliminarni okvir

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    The literature on "ethnic conflict" tends to focus solely on external sources of such conflict. But this unquestioning focus on ethnic conflict as due to factors in the relationship between "ethnic groups" or their elites may at times be misleading. Drawing on a critique of conflict theory as developed in the field of international relations, I point out the conceptual and methodological problems associated with the analysis of inter-group conflict, and point to the importance of within-group conflict, especially conflict between elites, as sources of external conflict. I apply this critique to the concept of ethnic conflict and point out the consequences of such questioning for understanding the causes of violent conflict along ethnic lines.U literaturi posvećenoj etničkim sukobima postoji tendencija da se u obzir uzmu samo izvanjski izvori sukoba. Takvo stajalište - da su glavni uzroci etničkih sukoba u karakteru odnosa među etničkim skupinama, odnosno njihovim elitama - može, međutim, biti pogrešno. U radu se izlaže kritika konfliktne teorije razrađene unutar znanstvenog (politologijskoga) područja međunarodnih odnosa. Kritika obuhvaća koncepcijske i metodološke probleme analize među-grupnih sukoba i ukazuje na važnost unutar-grupnih sukoba (sukoba među "domaćim" elitama) kao izvora onih prvih. U zaključku, autor ističe važnost izložene kritike za razumijevanje uzroka i izvora nasilnih sukoba koji slijede etničke markere

    The direct evaluation of attosecond chirp from a streaking measurement

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    We derive an analytical expression, from classical electron trajectories in a laser field, that relates the breadth of a streaked photoelectron spectrum to the group-delay dispersion of an isolated attosecond pulse. Based on this analytical expression, we introduce a simple, efficient and robust procedure to instantly extract the attosecond pulse's chirp from the streaking measurement.Comment: 4 figure

    Leading Order Calculation of Shear Viscosity in Hot Quantum Electrodynamics from Diagrammatic Methods

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    We compute the shear viscosity at leading order in hot Quantum Electrodynamics. Starting from the Kubo relation for shear viscosity, we use diagrammatic methods to write down the appropriate integral equations for bosonic and fermionic effective vertices. We also show how Ward identities can be used to put constraints on these integral equations. One of our main results is an equation relating the kernels of the integral equations with functional derivatives of the full self-energy; it is similar to what is obtained with two-particle-irreducible effective action methods. However, since we use Ward identities as our starting point, gauge invariance is preserved. Using these constraints obtained from Ward identities and also power counting arguments, we select the necessary diagrams that must be resummed at leading order. This includes all non-collinear (corresponding to 2 to 2 scatterings) and collinear (corresponding to 1+N to 2+N collinear scatterings) rungs responsible for the Landau-Pomeranchuk-Migdal effect. We also show the equivalence between our integral equations obtained from quantum field theory and the linearized Boltzmann equations of Arnold, Moore and Yaffe obtained using effective kinetic theory.Comment: 45 pages, 22 figures (note that figures 7 and 14 are downgraded in resolution to keep this submission under 1000kb, zoom to see them correctly

    Difference schemes with point symmetries and their numerical tests

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    Symmetry preserving difference schemes approximating second and third order ordinary differential equations are presented. They have the same three or four-dimensional symmetry groups as the original differential equations. The new difference schemes are tested as numerical methods. The obtained numerical solutions are shown to be much more accurate than those obtained by standard methods without an increase in cost. For an example involving a solution with a singularity in the integration region the symmetry preserving scheme, contrary to standard ones, provides solutions valid beyond the singular point.Comment: 26 pages 7 figure

    Contaminant (PAHs, OCs, PCBs and trace metals) concentrations are declining in axial tissue of sand flathead (Platycephalus bassensis) collected from an urbanised catchment (Port Phillip Bay, Australia)

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    © 2016 Elsevier Ltd. Concentrations of PAHs, OCs, PCBs and trace metals were determined in the white muscle of sand flathead Platycephalus bassensis collected at 6 locations in Port Phillip Bay during 2015. No PAHs, OCs or PCBs were detected in the white muscle of sand flathead at any of the locations, however measurable levels of As, Cu, Hg, Se and Zn were detected at all sites. Only As and Hg exhibited regional difference in white muscle concentrations, with As present only in a non-toxic organic form and Hg measured at levels that are comparable to levels reported in reference sites in other studies. All contaminants detected in the white muscle of sand flathead collected in Port Phillip Bay in 2015 were below Australian Food Standards guideline values, and by world standards, the Port Phillip Bay sand flathead population is considered minimally contaminated. Furthermore, tissue contaminant concentrations appear to be decreasing over time

    Symmetries of differential-difference dynamical systems in a two-dimensional lattice

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    Classification of differential-difference equation of the form u¨nm=Fnm(t,{upq}(p,q)Γ)\ddot{u}_{nm}=F_{nm}\big(t, \{u_{pq}\}|_{(p,q)\in \Gamma}\big) are considered according to their Lie point symmetry groups. The set Γ\Gamma represents the point (n,m)(n,m) and its six nearest neighbors in a two-dimensional triangular lattice. It is shown that the symmetry group can be at most 12-dimensional for abelian symmetry algebras and 13-dimensional for nonsolvable symmetry algebras.Comment: 24 pages, 1 figur

    Validation of a suite of biomarkers of fish health in the tropical bioindicator species, tambaqui (Colossoma macropomum)

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    Here we explore the dose-dependent response of the tropical fish tambaqui (Colossoma macropomum) to intraperitoneal injection of benzo[a]pyrene (BaP) at doses of 0 (carrier control), 1, 10, 100 and 1000 µmolar BaP Kg-1 Hepatic ethoxyresorufin-O-deethylase (EROD) activity showed a bell-shaped dose-dependent response curve, where the highest injected BaP dose caused enzyme inactivation. Activities of hepatic catalase (CAT) and superoxide dismutase (SOD) increased at the highest dose relative to the carrier control group. Lipid peroxidation (LPO), serum-sorbitol dehydrogenase (s-SDH) and DNA damage in blood cells were higher for all BaP doses when compared to the carrier control group. At high dosage, the production of BaP metabolites was paralleled by induced activity of the antioxidant enzyme SOD, and high levels of DNA damage in blood cells. In a similar way, high LPO was concomitant to elevated s-SDH in the bloodstream, suggesting that lipid peroxidation caused the loss of membrane integrity and leakage of s-SDH from hepatocytes into the bloodstream. These biomarkers were also positively co-correlated. The results demonstrate the potential use of a suite of biomarkers for tambaqui living in contaminated tropical aquatic environments. In particular, we recommend the analysis of DNA damage in blood cells, as this was highly correlated with all other biomarkers. © 2016 Elsevier Lt

    Participation and co-production in climate adaptation:Scope and limits identified from a meta-method review of research with European coastal communities

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    As climate change impacts increase, there are growing calls for strengthening relationships between researchers and other stakeholders to advance adaptation efforts. Participation and co-production are widely held to be key to such relationships, both intended to open substantive engagement in science and research to non-experts. Gains commonly attributed to participation and co-production include improved understanding of user needs and contexts, enhanced trust, creating actionable knowledge for adaptation planning and decision-making, and other new outcomes and practices supporting adaptation progress. At the same time, scrutiny of existing efforts to use participation and co-production reveals limits and gaps in understanding the conditions and processes required to undertake them in meaningful, appropriate and effective ways. This review assesses such limitations and gaps across the growing volume of research focused on adapting coastal and island communities within Europe. We systematically reviewed 60 peer-reviewed papers, drawing on a novel meta-method review approach to synthesise patterns in participation and co-production implementations, types of outcomes, and the latter’s associations with study research designs. We identify a propensity towards using more simplistic definitions of community, more conventional, extractive research methods in working with study communities, and emphasising knowledge generation over other outcomes. These issues are all limits on participation and co-production effectiveness, and we make recommendations to reduce them. We also recommend further recourse to systematic review methods to aid the development of participation and co-production knowledge for adaptation

    Fluid-Induced Propulsion of Rigid Particles in Wormlike Micellar Solutions

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    In the absence of inertia, a reciprocal swimmer achieves no net motion in a viscous Newtonian fluid. Here, we investigate the ability of a reciprocally actuated particle to translate through a complex fluid that possesses a network using tracking methods and birefringence imaging. A geometrically polar particle, a rod with a bead on one end, is reciprocally rotated using magnetic fields. The particle is immersed in a wormlike micellar (WLM) solution that is known to be susceptible to the formation of shear bands and other localized structures due to shear-induced remodeling of its microstructure. Results show that the nonlinearities present in this WLM solution break time-reversal symmetry under certain conditions, and enable propulsion of an artificial "swimmer." We find three regimes dependent on the Deborah number (De): net motion towards the bead-end of the particle at low De, net motion towards the rod-end of the particle at intermediate De, and no appreciable propulsion at high De. At low De, where the particle time-scale is longer then the fluid relaxation time, we believe that propulsion is caused by an imbalance in the fluid first normal stress differences between the two ends of the particle (bead and rod). At De~1, however, we observe the emergence of a region of network anisotropy near the rod using birefringence imaging. This anisotropy suggests alignment of the micellar network, which is "locked in" due to the shorter time-scale of the particle relative to the fluid
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