1,089 research outputs found

    Central Peripheries: Nationhood in Central Asia

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    Central Peripheries explores post-Soviet Central Asia through the prism of nation-building. Although relative latecomers on the international scene, the Central Asian states see themselves as globalized, and yet in spite of – or perhaps precisely because of – this, they hold a very classical vision of the nation-state, rejecting the abolition of boundaries and the theory of the ‘death of the nation’. Their unabashed celebration of very classical nationhoods built on post-modern premises challenges the Western view of nationalism as a dying ideology that ought to have been transcended by post-national cosmopolitanism. Marlene Laruelle looks at how states in the region have been navigating the construction of a nation in a post-imperial context where Russia remains the dominant power and cultural reference. She takes into consideration the ways in which the Soviet past has influenced the construction of national storylines, as well as the diversity of each state’s narratives and use of symbolic politics. Exploring state discourses, academic narratives and different forms of popular nationalist storytelling allows Laruelle to depict the complex construction of the national pantheon in the three decades since independence. The second half of the book focuses on Kazakhstan as the most hybrid national construction and a unique case study of nationhood in Eurasia. Based on the principle that only multidisciplinarity can help us to untangle the puzzle of nationhood, Central Peripheries uses mixed methods, combining political science, intellectual history, sociology and cultural anthropology. It is inspired by two decades of fieldwork in the region and a deep knowledge of the region’s academia and political environment

    Energy spectra of quasiperiodic systems via information entropy

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    We study the relationship between the electronic spectrum structure and the configurational order of one-dimensional quasiperiodic systems. We take the Fibonacci case as an specific example, but the ideas outlined here may be useful to accurately describe the energy spectra of general quasiperiodic systems of technological interest. Our main result concerns the {\em minimization} of the information entropy as a characteristic feature associated to quasiperiodic arrangements. This feature is shown to be related to the ability of quasiperiodic systems to encode more information, in the Shannon sense, than periodic ones. In the conclusion we comment on interesting implications of these results on further developments on the issue of quasiperiodic order.Comment: REVTeX 3.0, 8 pages, 3 figures available on request from FD-A ([email protected]), Phys Rev E submitted, MA/UC3M/02/9

    Locomotor hyperactivity in 14-3-3Zeta KO mice is associated with dopamine transporter dysfunction

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    Dopamine (DA) neurotransmission requires a complex series of enzymatic reactions that are tightly linked to catecholamine exocytosis and receptor interactions on pre- and postsynaptic neurons. Regulation of dopaminergic signalling is primarily achieved through reuptake of extracellular DA by the DA transporter (DAT) on presynaptic neurons. Aberrant regulation of DA signalling, and in particular hyperactivation, has been proposed as a key insult in the presentation of schizophrenia and related neuropsychiatric disorders. We recently identified 14-3-3ζ as an essential component of neurodevelopment and a central risk factor in the schizophrenia protein interaction network. Our analysis of 14-3-3ζ-deficient mice now shows that baseline hyperactivity of knockout (KO) mice is rescued by the antipsychotic drug clozapine. 14-3-3ζ KO mice displayed enhanced locomotor hyperactivity induced by the DA releaser amphetamine. Consistent with 14-3-3ζ having a role in DA signalling, we found increased levels of DA in the striatum of 14-3-3ζ KO mice. Although 14-3-3ζ is proposed to modulate activity of the rate-limiting DA biosynthesis enzyme, tyrosine hydroxylase (TH), we were unable to identify any differences in total TH levels, TH localization or TH activation in 14-3-3ζ KO mice. Rather, our analysis identified significantly reduced levels of DAT in the absence of notable differences in RNA or protein levels of DA receptors D1–D5. Providing insight into the mechanisms by which 14-3-3ζ controls DAT stability, we found a physical association between 14-3-3ζ and DAT by co-immunoprecipitation. Taken together, our results identify a novel role for 14-3-3ζ in DA neurotransmission and provide support to the hyperdopaminergic basis of pathologies associated with schizophrenia and related disorders.H Ramshaw, X Xu, EJ Jaehne, P McCarthy, Z Greenberg, E Saleh, B McClure, J Woodcock, S Kabbara, S Wiszniak, Ting-Yi Wang, C Parish, M van den Buuse, BT Baune, A Lopez and Q Schwar

    Fermi-Edge Singularities in AlxGa1-xAs Quantum Wells : Extrinsic Versus Many-Body Scattering Processes

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    A Fano resonance mechanism is evidenced to control the formation of optical Fermi-edge singularities in multi-subband systems such as remotely doped AlxGa1-xAs heterostructures. Using Fano parameters, we probe the physical nature of the interaction between Fermi-sea electrons and empty conduction subbands. We show that processes of extrinsic origin like alloy-disorder prevail easily at 2D over multiple diffusions from charged valence holes expected by many-body scenarios.Comment: 4 pages, 3 figures, accepted for publication in Physical Review Letter

    Dynamical phenomena in Fibonacci Semiconductor Superlattices

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    We present a detailed study of the dynamics of electronic wavepackets in Fibonacci semiconductor superlattices, both in flat band conditions and subject to homogeneous electric fields perpendicular to the layers. Coherent propagation of electrons is described by means of a scalar Hamiltonian using the effective-mass approximation. We have found that an initial Gaussian wavepacket is filtered selectively when passing through the superlattice. This means that only those components of the wavepacket whose wavenumber belong to allowed subminibands of the fractal-like energy spectrum can propagate over the entire superlattice. The Fourier pattern of the transmitted part of the wavepacket presents clear evidences of fractality reproducing those of the underlying energy spectrum. This phenomenon persists even in the presence of unintentional disorder due to growth imperfections. Finally, we have demonstrated that periodic coherent-field induced oscillations (Bloch oscillations), which we are able to observe in our simulations of periodic superlattices, are replaced in Fibonacci superlattices by more complex oscillations displaying quasiperiodic signatures, thus sheding more light onto the very peculiar nature of the electronic states in these systems.Comment: 7 pagex, RevTex, 5 Postscript figures. Physical Review B (in press

    A Russian Radical Conservative Challenge to the Liberal Global Order: Aleksandr Dugin

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    The chapter examines Russian political theorist Aleksandr Dugin’s (b. 1962) challenge to the Western liberal order. Even though Dugin’s project is in many ways a theoretical epitome of Russia’s contemporary attempt to profile itself as a regional great power with a political and cultural identity distinct from the liberal West, Dugin can also be read in a wider context as one of the currently most prominent representatives of the culturally and intellectually oriented international New Right. The chapter introduces Dugin’s role on the Russian right-wing political scene and his international networks, Russian neo-Eurasianism as his ideological footing, and his more recent “fourth political theory” as an attempt to formulate a new ideological alternative to liberalism as well as the two other main twentieth-century ideologies, communism and fascism. Dugin’s fourth ideology, essentially meant as an alternative to a unipolar post–Cold War global hegemony of victorious liberalism, draws inspiration from the German conservative revolutionary movement of the Weimar era. In particular, Martin Heidegger’s philosophy of history, with its thesis of the end of modernity and another beginning of Western thought, and Carl Schmitt’s pluralistic model of geopolitics are highlighted as key elements of Dugin’s eclectic political thought, which is most appropriately characterized as a form of radical conservatism

    Multifractal analysis of the electronic states in the Fibonacci superlattice under weak electric fields

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    Influence of the weak electric field on the electronic structure of the Fibonacci superlattice is considered. The electric field produces a nonlinear dynamics of the energy spectrum of the aperiodic superlattice. Mechanism of the nonlinearity is explained in terms of energy levels anticrossings. The multifractal formalism is applied to investigate the effect of weak electric field on the statistical properties of electronic eigenfunctions. It is shown that the applied electric field does not remove the multifractal character of the electronic eigenfunctions, and that the singularity spectrum remains non-parabolic, however with a modified shape. Changes of the distances between energy levels of neighbouring eigenstates lead to the changes of the inverse participation ratio of the corresponding eigenfunctions in the weak electric field. It is demonstrated, that the local minima of the inverse participation ratio in the vicinity of the anticrossings correspond to discontinuity of the first derivative of the difference between marginal values of the singularity strength. Analysis of the generalized dimension as a function of the electric field shows that the electric field correlates spatial fluctuations of the neighbouring electronic eigenfunction amplitudes in the vicinity of anticrossings, and the nonlinear character of the scaling exponent confirms multifractality of the corresponding electronic eigenfunctions.Comment: 10 pages, 9 figure

    Effects of N-acetylcysteine on amphetamine-induced sensitization in mice

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    Objective: N-acetylcysteine (NAC) is beneficial in psychiatric conditions, including schizophrenia. Patients with schizophrenia exhibit mesolimbic dopamine hyperfunction consequent to an endogenous sensitization process. This sensitization can be modeled in rodents by repeated exposure to psychostimulants, provoking an enduring amplified response at subsequent exposure. The aim of this study was to investigate the effects of NAC on amphetamine sensitization in mice. Methods: D-amphetamine was administered to C57BL/6 mice three times a week for 3 weeks; the dose was increased weekly from 1 to 3 mg/kg. NAC (60 mg/kg) or saline was administered intraperitoneally before saline or amphetamine during the second and third weeks. After a 4-week washout period, latent inhibition (LI) and the locomotor response to amphetamine 2 mg/kg were assessed. Results: Sensitization disrupted LI and amplified the locomotor response; NAC disrupted LI in control mice. In sensitized animals, NAC attenuated the enhanced locomotion but failed to prevent LI disruption. Conclusion: NAC warrants consideration as a candidate for early intervention in ultra-high risk subjects due to its safety profile and the relevance of its mechanism of action. Supplementing this proposition, we report that NAC attenuates sensitization-induced locomotor enhancement in mice. The finding that NAC disrupted LI incites a cautionary note and requires clarification
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