16,037 research outputs found

    Unusual Features of Varying Speed of Light Cosmologies

    Get PDF
    We contrast features of simple varying speed of light (VSL) cosmologies with inflationary universe models. We present new features of VSL cosmologies and show that they face problems explaining the cosmological isotropy problem. We also find that if c falls fast enough to solve the flatness and horizon problems then the quantum wavelengths of massive particle states and the radii of primordial black holes can grow to exceed the scale of the particle horizon. This may provide VSL cosmologies with a self-reproduction property. The constraint of entropy increase is also discussed. The new problems described in the this letter provide a set of bench tests for more sophisticated VSL theories to pass.Comment: expanded version, 12 page

    Moduli constraints on primordial black holes

    Get PDF
    The amount of late decaying massive particles (e.g., gravitinos, moduli) produced in the evaporation of primordial black holes (PBHs) of mass \Mbh\la10^9 g is calculated. Limits imposed by big-bang nucleosynthesis on the abundance of these particles are used to constrain the initial PBH mass fraction ÎČ\beta (ratio of PBH energy density to critical energy density at formation), as: \beta\la 5\times10^{-19} (\xp/6 10^{-3})^{-1} (\Mbh/10^9 {\rm g})^{-1/2} (\bar{\Yp}/10^{-14}); \xp is the fraction of PBH luminosity going into gravitinos or moduli, \bar{\Yp} is the upper bound imposed by nucleosynthesis on the number density to entropy density ratio of gravitinos or moduli. This notably implies that such PBHs should never come to dominate the cosmic energy density.Comment: 8 page

    Common exercise prescription for management of weight and osteoarthritis : a systematic review : a thesis presented in partial fulfilment of the requirements for the degree of Master of Sport and Exercise at Massey University, Wellington, New Zealand

    Get PDF
    Background: Obesity and osteoarthritis are two debilitating conditions that are increasing in prevalence. Obese populations are at an increased risk for developing osteoarthritis in later life. Exercise has been shown to be successful in improving both weight status and musculoskeletal pain, yet it remains unclear if there is an exercise intervention that results in improved weight status while preventing the development of osteoarthritis. Objective: The purpose of this systematic review is to investigate the existence of a natural overlap in exercise prescription for obese and osteoarthritic populations and recommend an evidence-based exercise intervention for the management of weight and prevention of musculoskeletal pain. Methods: A structured electronic review was conducted using the following electronic databases: MEDLINE, PubMed, and SPORTDiscus. Two searches were performed using the search strings “obes*” AND “exercise” AND “interven*” AND “musculoskeletal pain OR knee pain OR hip pain” and “osteoarth*” AND “exercise” AND “interven*” AND “musculoskeletal pain OR knee pain OR hip pain”. Studies were then reviewed using inclusion/exclusion criteria (exclusion criteria: menopausal, cancer, review, obesity related co-morbidities, animal studies; inclusion criteria: studies had to be randomised controlled trials, participants aged 18-50, include non-exercise control, and outcomes must include physical function or musculoskeletal pain). Included studies were ranked by change in measured outcome variables (descending order); a summary of recommended exercise prescription was based on common prescription used in the interventions with greatest change. A Downs and Black checklist was completed for all studies included in this review to assess methodological quality. Results: Twenty-one studies met inclusion criteria and were included in this review (obesity n = 11; OA n = 7; obesity & OA n= 3). Exercise significantly improved weight status and/or musculoskeletal pain. Similarities in exercise intensity (40-80% VO2max), frequency (3 times per week), duration (30-60 minutes), and exercise mode (treadmill, cross-trainer, stationary bike, aquatic exercise) were observed between studies. Conclusion: Substantial overlap in exercise prescription for obese and OA populations exist. These findings suggest that moderate intensity exercise for 30-60 minutes, 3 times per weeks can achieve effective improvements in weight and musculoskeletal pain. Exercise and weight loss are effective treatments for obesity and musculoskeletal symptoms and should be recommended to all at-risk individuals

    Images of Peru: a national cinema in crisis

    Get PDF
    A brief look at the major trends in the history of the national cinema of Peru suggests that the relationship between the development of the moving image and the onset of modernity in that country has always been awkward. Many have argued that the advent of cinema coincided in most parts of the world with the decades when modernity was already ‘at full throttle . . . a watershed moment in which a series of sweeping changes in technology and culture created distinctive new modes of thinking about and experiencing time and space’. However, the reality for the majority of Latin American countries was quite different. As Ana M. López points out, it simply is not possible to link the rise of cinema in that part of the world to ‘previous large-scale transformations of daily experience resulting from urbanization, industrialization, rationality and the technological transformation of modern life’. Such developments were only just starting to emerge, so that as cinema was launched across the world, modernity in Latin America ‘was above all a fantasy and a profound desire.

    New configurations for Peruvian cinema: the rising star of Claudia Llosa

    Get PDF
    After a decade-long hiatus during which the existence of a home-grown cinema in Peru had been threatened by a lack of government and public support, a new generation of directors broke onto the scene in the twenty-first century with a distinctive approach to both the production and circulation of their films, as well as to their relationship with the ‘national’, in terms of policy, funding and audience engagement. This study takes one of those directors, Claudia Llosa, as the main case study, and considers the development of her profile as an internationally recognized Peruvian film-maker whose award-winning debut works (Madeinusa, 2006 and La Teta Asustada/Milk of Sorrow, 2009) sparked controversy and critical debate for their challenging portrayals of the Quechua culture of Peru. This article examines her successes on the international festival and commercial exhibition circuits, considers some of the scholarly and critical responses to her work, and asks what impact Llosa has had on the development of cinema in Peru through her engagement with the transnational

    Peruvian cinema, national identity and political violence 1988-2004

    Get PDF
    The role of national cinema in shaping, reflecting and contesting a complex national identity that is the site of conflict and struggle is the central interest of this study of contemporary Peruvian cinema, 1988-2004. This project examines the relationship between cinema, state and identity in Peru, with a specific focus on the representation of the political violence between the state and Sendero Luminoso (Shining Path) that began in 1980. It looks in particular at portrayals of important events, characters and consequences of the bloody conflict that for a time threatened to destabilize the nation entirely. It considers these representations in the context of a time of great change for Peruvian society and of transition for Peruvian national cinema, and addresses the relationship between developments in film policy and the formation of Peruvian national identity in cinema. As such, it draws on debates about the nature and function of national cinemas, as well as on discussions between artists, cultural theorists and sociologists about the evolution of peruanidad since the declaration of independence from Spain in the early nineteenth century. Once the main elements of the cinematic and social crises have been explored and established in Chapters Two and Three, the remainder of the project consists of three sets of chronologically ordered analyses of individual films that somehow defied the national cinema crisis, and that provoked debate on both the conflict itself, and on broader questions pertaining to the relationship between national identity and violence. The conclusion considers these films as an interlinked body of cinematic works that share similar themes and concerns. It summarises the issues they tackle, the ideological and formal approaches they take to those issues, the potential social and cultural impact, and their contribution to the crystallization of a Peruvian national identity at the start of the twenty-first century

    Stable Isotropic Cosmological Singularities in Quadratic Gravity

    Get PDF
    We show that, in quadratic lagrangian theories of gravity, isotropic cosmological singularities are stable to the presence of small scalar, vector and tensor inhomogeneities. Unlike in general relativity, a particular exact isotropic solution is shown to be the stable attractor on approach to the initial cosmological singularity. This solution is also known to act as an attractor in Bianchi universes of types I, II and IX, and the results of this paper reinforce the hypothesis that small inhomogeneous and anisotropic perturbations of this attractor form part of the general cosmological solution to the field equations of quadratic gravity. Implications for the existence of a 'gravitational entropy' are also discussed.Comment: 18 pages, no figure
    • 

    corecore