General features of Bianchi-I cosmological models in Lovelock gravity

We derived equations of motion corresponding to Bianchi-I cosmological models in the Lovelock gravity. Equations derived in the general case, without any specific ansatz for any number of spatial dimensions and any order of the Lovelock correction. We also analyzed the equations of motion solely taking into account the highest-order correction and described the drastic difference between the cases with odd and even numbers of spatial dimensions. For power-law ansatz we derived conditions for Kasner and generalized Milne regimes for the model considered. Finally, we discuss the possible influence of matter in the form of perfect fluid on the solutions obtained.Comment: extended version of published Brief Repor

On the naturalness of Einstein's equation

We compute all 2-covariant tensors naturally constructed from a semiriemannian metric which are divergence-free and have weight greater than -2. As a consequence, it follows a characterization of the Einstein tensor as the only, up to a constant factor, 2-covariant tensor naturally constructed from a semiriemannian metric which is divergence-free and has weight 0 (i.e., is independent of the unit of scale). Since these two conditions are also satisfied by the energy-momentum tensor of a relativistic space-time, we discuss in detail how these theorems lead to the field equation of General Relativity.Comment: 12 pages, added references, corrected typo

Moon Prism Boys: The Magical Boy as Queering Device

Through a queer lens, this thesis examines the role that the magical boy character plays in the manga Magical Boy Majorian (2007-2008), and in season 15 of the popular magical girl genre anime franchise Pretty Cure, entitled Hugtto! PreCure (2018-2019). Using queer theory and gender studies research, this thesis argues that the magical boy figure challenges problematic forms of masculinity by performing what I call ‘shōjoness,’ a particular form of feminine aesthetic mainly found in shōjo (for girls) manga, and anime. The thesis contends that henshin (transformation) sequences allow a space for gender negotiation, which disrupts a heteronormative structure through the crossing, and blending, of gender expression and form. Acting as what Sedgwick calls a queer survival object (1993), the magical boy becomes a site for queer representation, but also what I call a queering device. In other words, this thesis argues that Majorian and Hugtto serve as escapes from the burden of heteronormativity, while also holding to some extent the power to inspire change in attitudes toward queerness within, and beyond the pages of the manga, or the screen of anime. Analyzing key scenes from both works mentioned above, this thesis explores how medium specificity (manga structure, and animation techniques) renders queerness by contrasting it with more standard ways of drawing, and animating, consequently challenging normative ways of being. Informed by Scott McCloud’s theorizing of the gutter, Thomas Lamarre’s work on the interval, and Sara Ahmed’s discussion on queer orientation, Moon Prism Boys frames particular forms of interstices as spaces that have the potential to positively disturb a monolithic form of masculinity when brought into contact with queerness

Variational Principles for Natural Divergence-free Tensors in Metric Field Theories

Let $T^{ab}=T^{ba}=0$ be a system of differential equations for the components of a metric tensor on $R^m$. Suppose that $T^{ab}$ transforms tensorially under the action of the diffeomorphism group on metrics and that the covariant divergence of $T^{ab}$ vanishes. We then prove that $T^{ab}$ is the Euler-Lagrange expression some Lagrangian density provided that $T^{ab}$ is of third order. Our result extends the classical works of Cartan, Weyl, Vermeil, Lovelock, and Takens on identifying field equations for the metric tensor with the symmetries and conservation laws of the Einstein equations

Cosmology in three dimensions: steps towards the general solution

We use covariant and first-order formalism techniques to study the properties of general relativistic cosmology in three dimensions. The covariant approach provides an irreducible decomposition of the relativistic equations, which allows for a mathematically compact and physically transparent description of the 3-dimensional spacetimes. Using this information we review the features of homogeneous and isotropic 3-d cosmologies, provide a number of new solutions and study gauge invariant perturbations around them. The first-order formalism is then used to provide a detailed study of the most general 3-d spacetimes containing perfect-fluid matter. Assuming the material content to be dust with comoving spatial 2-velocities, we find the general solution of the Einstein equations with non-zero (and zero) cosmological constant and generalise known solutions of Kriele and the 3-d counterparts of the Szekeres solutions. In the case of a non-comoving dust fluid we find the general solution in the case of one non-zero fluid velocity component. We consider the asymptotic behaviour of the families of 3-d cosmologies with rotation and shear and analyse their singular structure. We also provide the general solution for cosmologies with one spacelike Killing vector, find solutions for cosmologies containing scalar fields and identify all the PP-wave 2+1 spacetimes.Comment: 35 pages, 2 figure

Potential vectors of equine arboviruses in the UK

There is growing concern about the increasing risk of disease outbreaks caused by arthropod-borne viruses (arboviruses) in both humans and animals. There are several mosquito-borne viral diseases that cause varying levels of morbidity and mortality in horses and that can have substantial welfare and economic ramifications. While none has been recorded in the UK, vector species for some of these viruses are present, suggesting that UK equines may be at risk. We undertook, therefore, the first study of mosquito species on equine premises in the UK. Mosquito Magnet traps and red-box traps were used to sample adults, and larvae were collected from water sources such as tyres, buckets, ditches and pools. Several species which are known to be capable of transmitting important equine infectious arboviruses were trapped. The most abundant, with a maximum catch of 173 in 72 hours was Ochlerotatus detritus, a competent vector of some flaviviruses; the highest densities were found near saltmarsh habitats. The most widespread species, recorded at >75% of sites, was Culiseta annulata. This study demonstrates that potential mosquito vectors of arboviruses, including those known to be capable of infecting horses, are present and may be abundant on equine premises in the UK

Culex pipiens, an Experimental Efficient Vector of West Nile and Rift Valley Fever Viruses in the Maghreb Region

West Nile fever (WNF) and Rift Valley fever (RVF) are emerging diseases causing epidemics outside their natural range of distribution. West Nile virus (WNV) circulates widely and harmlessly in the old world among birds as amplifying hosts, and horses and humans as accidental dead-end hosts. Rift Valley fever virus (RVFV) re-emerges periodically in Africa causing massive outbreaks. In the Maghreb, eco-climatic and entomologic conditions are favourable for WNV and RVFV emergence. Both viruses are transmitted by mosquitoes belonging to the Culex pipiens complex. We evaluated the ability of different populations of Cx. pipiens from North Africa to transmit WNV and the avirulent RVFV Clone 13 strain. Mosquitoes collected in Algeria, Morocco, and Tunisia during the summer 2010 were experimentally infected with WNV and RVFV Clone 13 strain at titers of 107.8 and 108.5 plaque forming units/mL, respectively. Disseminated infection and transmission rates were estimated 14–21 days following the exposure to the infectious blood-meal. We show that 14 days after exposure to WNV, all mosquito st developed a high disseminated infection and were able to excrete infectious saliva. However, only 69.2% of mosquito strains developed a disseminated infection with RVFV Clone 13 strain, and among them, 77.8% were able to deliver virus through saliva. Thus, Cx. pipiens from the Maghreb are efficient experimental vectors to transmit WNV and to a lesser extent, RVFV Clone 13 strain. The epidemiologic importance of our findings should be considered in the light of other parameters related to mosquito ecology and biology

North American blastomycosis

North American blastomycosis (Gilchrist's disease) in a granulomatous, infectious disease caused by the fungus, Blastomyces dermatitidis (Gilchrist and Stokes, 1898). The malady, in its cutaneous form, was first described by Gilchrist1 in 1894. A few years later, together with Stokes, he was able to isolate and culture that causative organisms which he designated as B. dermatitibis.23 The first description of the disease in its systemic form was made by Walker and Montgomery4 in 1902.The first reports by Gilchrist were followed by an era of confusion during which the disease was confounded with other entities, particularly cryptococcosis and candidiasis, all caused by morphologically similar budding organisms. Nineteen new names were suggested for the causative fungus. During the last two decades, however, a clearer picture of the disease process has emerged, particularly as a result of studies by the Duke Medical School group, headed by Smith, Martin, and Conant. Numerous clinical and laboratory reports have contributed significantly to a fuller understanding of the disease, but there are still some fundamental question to be answered. Excellent review articles on North American blastomycosis are available.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32504/1/0000592.pd