8,484 research outputs found

    First the forest: conservation, 'community' and 'participation' in South West Cameroon

    Get PDF
    Western concern with ‘conserving’ or ‘managing’ the rain forests of Africa has led to the setting up of a number of conservation projects. In such projects the ‘participation’ of the ‘community’ in forest conservation has become the new orthodoxy. However, proposals about local people's participation presume that defining the future of the forest is a straight contest between the alternatives of conservation or forest clearing. Such proposals also presume that the existence of communities is non-problematic. In contrast, this article documents that there is already considerable local debate about forest use and conservation, much of it among those excluded from the formal arena of politics and policy-making. Concern with ‘the environment’ includes concern about the perpetuation of society, and represents a clear continuation of West African village cosmologies focused on the societalisation of space. At the same time, conservation aims of ‘keeping the forest as it is’ have few resonances, since forest people see society itself as an artful, but often problematic, construction in which the conversion of the forest plays a central part. In conclusion, the article suggests that the key to environmental management must be for external agencies to articulate with the interests and values of those who hold a legitimate stake in African forest resources

    Notes on nonabelian (0,2) theories and dualities

    Get PDF
    In this paper we explore basic aspects of nonabelian (0,2) GLSM's in two dimensions for unitary gauge groups, an arena that until recently has largely been unexplored. We begin by discussing general aspects of (0,2) theories, including checks of dynamical supersymmetry breaking, spectators and weak coupling limits, and also build some toy models of (0,2) theories for bundles on Grassmannians, which gives us an opportunity to relate physical anomalies and trace conditions to mathematical properties. We apply these ideas to study (0,2) theories on Pfaffians, applying recent perturbative constructions of Pfaffians of Jockers et al. We discuss how existing dualities in (2,2) nonabelian gauge theories have a simple mathematical understanding, and make predictions for additional dualities in (2,2) and (0,2) gauge theories. Finally, we outline how duality works in open strings in unitary gauge theories, and also describe why, in general terms, we expect analogous dualities in (0,2) theories to be comparatively rare.Comment: 93 pages, LaTeX; v2: typos fixe

    Partially quenched chiral perturbation theory without Φ0\Phi_0

    Get PDF
    This paper completes the argument that lattice simulations of partially quenched QCD can provide quantitative information about QCD itself, with the aid of partially quenched chiral perturbation theory. A barrier to doing this has been the inclusion of Φ0\Phi_0, the partially quenched generalization of the η\eta', in previous calculations in the partially quenched effective theory. This invalidates the low energy perturbative expansion, gives rise to many new unknown parameters, and makes it impossible to reliably calculate the relation between the partially quenched theory and low energy QCD. We show that it is straightforward and natural to formulate partially quenched chiral perturbation theory without Φ0\Phi_0, and that the resulting theory contains the effective theory for QCD without the η\eta'. We also show that previous results, obtained including Φ0\Phi_0, can be reinterpreted as applying to the theory without Φ0\Phi_0. We contrast the situation with that in the quenched effective theory, where we explain why it is necessary to include Φ0\Phi_0. We also compare the derivation of chiral perturbation theory in partially quenched QCD with the standard derivation in unquenched QCD. We find that the former cannot be justified as rigorously as the latter, because of the absence of a physical Hilbert space. Finally, we present an encouraging result: unphysical double poles in certain correlation functions in partially quenched chiral perturbation theory can be shown to be a property of the underlying theory, given only the symmetries and some plausible assumptions.Comment: 45 pages, no figure

    Quantization of Fayet-Iliopoulos Parameters in Supergravity

    Full text link
    In this short note we discuss quantization of the Fayet-Iliopoulos parameter in supergravity theories. We argue that in supergravity, the Fayet-Iliopoulos parameter determines a lift of the group action to a line bundle, and such lifts are quantized. Just as D-terms in rigid N=1 supersymmetry are interpreted in terms of moment maps and symplectic reductions, we argue that in supergravity the quantization of the Fayet-Iliopoulos parameter has a natural understanding in terms of linearizations in geometric invariant theory (GIT) quotients, the algebro-geometric version of symplectic quotients.Comment: 21 pages, utarticle class; v2: typos and tex issue fixe

    Six Pillars of Social Policy: The State of Pensions and Health Care in Canada

    Get PDF
    William B.P. Robson, a co-author with David Slater of a series of papers on pension issues, has written an ambitious survey of the state of Canadian economic policy in the areas of pensions and health care. He argues that it is appropriate to tackle both issues in the same paper because they are both major spending programs strongly related to the life cycle of Canadians, and face challenges arising from the aging of the population. Robson notes that the pension debate uses the metaphor of three pillars to describe a comprehensive pension system: a safety net to guard against destitution in old age; a mandatory employment-related system to provide basic replacement income; and a voluntary system supported by provisions that reduce the double-taxation of saving. The main elements of public policy related to pensions in Canada cover these pillars. He recognizes that all three of the pillars cannot be directly applied to health care, but he argues that the three-pillar metaphor is still a fruitful perspective because it facilitates constructive responses to the pressures confronting Canada’s health system and illuminates interactions between the pension and health systems. Hence his title “six pillars of social policy”. Based on his examination of Canada’s pension and health-care systems, Robson makes a number of recommendations. First, he advocates more prefunding in both the pension and health areas to cover the future cost of the aging baby-boom cohort. Second, he recommends a gradual increase in the normal age of eligibility for pension benefits. Third, he recommends the creation of a second pillar, a mandatory contribution scheme in the health area as a way to avoid the development of a means-tested system that would exacerbate the disincentives to work and save. Fourth, he puts forward the idea of a new type of saving vehicle that provides tax-relief on distributions rather than on contributions so that Canadians can avoid the high marginal effective tax rates associated with means-tested programs.Health, Health Care, Health-care, Healthcare, Canada, Pensions, CPP, Retirement, Mandatory Contribution, Aging, Ageing

    Chiral operators in two-dimensional (0,2) theories and a test of triality

    Full text link
    In this paper we compute spaces of chiral operators in general two-dimensional (0,2) nonlinear sigma models, both in theories twistable to the A/2 or B/2 model, as well as in non-twistable theories, and apply them to check recent duality conjectures. The fact that in a nonlinear sigma model, the Fock vacuum can act as a section of a line bundle on the target space plays a crucial role in our (0,2) computations, so we begin with a review of this property. We also take this opportunity to show how even in (2,2) theories, the Fock vacuum encodes in this way choices of target space spin structures, and discuss how such choices enter the A and B model topological field theories. We then compute chiral operators in general (0,2) nonlinear sigma models, and apply them to test the recent Gadde-Gukov-Putrov triality proposal, which says that certain triples of (0,2) GLSMs should RG flow to nontrivial IR fixed points. We find that different UV theories in the same proposed universality class do not necessarily have the same space of chiral operators -- but, the mismatched operators do not contribute to elliptic genera and are in non-integrable representations of the proposed IR affine symmetry groups, suggesting that the mismatched states become massive along RG flow. We find this state matching in examples not only of different geometric phases of the same GLSMs, but also in phases of different GLSMs, indirectly verifying the triality proposal, and giving a clean demonstration that (0,2) chiral rings are not topologically protected. We also check proposals for enhanced IR affine E_6 symmetries in one such model, verifying that (matching) chiral states in phases of corresponding GLSMs transform as 27s, 27^*s.Comment: 51 pages, LaTeX. v2: minor revisions. v3: some references adde

    Development of the elevation drive assembly for orbiting solar observatory I (EYE)

    Get PDF
    The requirements for pointing accuracy, friction, and power for the elevation drive assembly of an orbiting space observatory are discussed briefly. A description of the components making up the assembly is presented. Special features requiring development testing prior to unit fabrication are more fully described together with a review of the test programs conducted and results obtained

    Heavy-Meson Observables at One-Loop in Partially Quenched Chiral Perturbation Theory

    Get PDF
    I present one-loop level calculations of the Isgur-Wise functions for B -> D^{(*)} + e + nu, of the matrix elements of isovector twist-2 operators in B and D mesons, and the matrix elements for the radiative decays D^* -> D + gamma in partially quenched heavy quark chiral perturbation theory. Such expressions are required in order to extrapolate from the light quark masses used in lattice simulations of the foreseeable future to those of nature.Comment: 13 pages, 3 fig

    Introduction to the new usability

    Get PDF
    This paper introduces the motivation for and concept of the "new usability" and positions it against existing approaches to usability. It is argued that the contexts of emerging products and systems mean that traditional approaches to usability engineering and evaluation are likely to prove inappropriate to the needs of "digital consumers." The paper briefly reviews the contributions to this special issue in terms of their relation to the idea of the "new usability" and their individual approaches to dealing with contemporary usability issues. This helps provide a background to the "new usability" research agenda, and the paper ends by posing what are argued to be the central challenges facing the area and those which lie at the heart of the proposed research agenda
    corecore