Ambient connections realising conformal Tractor holonomy

For a conformal manifold we introduce the notion of an ambient connection, an affine connection on an ambient manifold of the conformal manifold, possibly with torsion, and with conditions relating it to the conformal structure. The purpose of this construction is to realise the normal conformal tractor holonomy as affine holonomy of such a connection. We give an example of an ambient connection for which this is the case, and which is torsion free if we start the construction with a C-space, and in addition Ricci-flat if we start with an Einstein manifold. Thus for a $C$-space this example leads to an ambient metric in the weaker sense of \v{C}ap and Gover, and for an Einstein space to a Ricci-flat ambient metric in the sense of Fefferman and Graham.Comment: 17 page

Wake Development behind Paired Wings with Tip and Root Trailing Vortices: Consequences for Animal Flight Force Estimates

Recent experiments on flapping flight in animals have shown that a variety of unrelated species shed a wake behind left and right wings consisting of both tip and root vortices. Here we present an investigation using Particle Image Velocimetry (PIV) of the behaviour and interaction of trailing vortices shed by paired, fixed wings that simplify and mimic the wake of a flying animal with a non-lifting body. We measured flow velocities at five positions downstream of two adjacent NACA 0012 aerofoils and systematically varied aspect ratio, the gap between the wings (corresponding to the width of a non-lifting body), angle of attack, and the Reynolds number. The range of aspect ratios and Reynolds number where chosen to be relevant to natural fliers and swimmers, and insect flight in particular. We show that the wake behind the paired wings deformed as a consequence of the induced flow distribution such that the wingtip vortices convected downwards while the root vortices twist around each other. Vortex interaction and wake deformation became more pronounced further downstream of the wing, so the positioning of PIV measurement planes in experiments on flying animals has an important effect on subsequent force estimates due to rotating induced flow vectors. Wake deformation was most severe behind wings with lower aspect ratios and when the distance between the wings was small, suggesting that animals that match this description constitute high-risk groups in terms of measurement error. Our results, therefore, have significant implications for experimental design where wake measurements are used to estimate forces generated in animal flight. In particular, the downstream distance of the measurement plane should be minimised, notwithstanding the animal welfare constraints when measuring the wake behind flying animals

Macrophage migration inhibitory factor expression in male and female ethanol-fed rats

Macrophage migration inhibitory factory (MIF) regulates macrophage accumulation at sites of injury and can promote the inflammatory response. We studied MIF expression in the intragastric feeding rat model for alcoholic liver injury. Male and age-matched female rats were fed ethanol or dextrose with fish oil. Two groups of male rats were fed medium-chain triglycerides with ethanol or dextrose. Analysis of liver histopathology, lipid peroxidation, endotoxin, mRNA, and immunohistochemistry for MIF, tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) were carried out. Male and female rats fed fish oil and ethanol showed necroinflammatory liver injury and had the highest expression of MIF, TNF-α, and IFN-γ in the liver. Decreased levels of MIF protein were seen in rats with higher endotoxin levels, suggesting that preformed MIF is released into the circulation. MIF is an important mediator of the inflammatory response in alcoholic liver disease and a potential therapeutic target.published_or_final_versio

Einstein metrics in projective geometry

It is well known that pseudo-Riemannian metrics in the projective class of a given torsion free affine connection can be obtained from (and are equivalent to) the solutions of a certain overdetermined projectively invariant differential equation. This equation is a special case of a so-called first BGG equation. The general theory of such equations singles out a subclass of so-called normal solutions. We prove that non-degerate normal solutions are equivalent to pseudo-Riemannian Einstein metrics in the projective class and observe that this connects to natural projective extensions of the Einstein condition.Comment: 10 pages. Adapted to published version. In addition corrected a minor sign erro

Signatures of hermitian forms and the Knebusch Trace Formula

Signatures of quadratic forms have been generalized to hermitian forms over algebras with involution. In the literature this is done via Morita theory, which causes sign ambiguities in certain cases. In this paper, a hermitian version of the Knebusch Trace Formula is established and used as a main tool to resolve these ambiguities. The last page is an erratum for the published version. We inadvertently (I) gave an incorrect definition of adjoint involutions; (II) omitted dealing with the case $(H\times H, \widehat{\phantom{m}}\,)$. As $W(H\times H, \widehat{\phantom{m}}\,)= W(R\times R, \widehat{\phantom{m}}\,)=0$, the omission does not affect our reasoning or our results. For the sake of completeness we point out where some small changes should be made in the published version.Comment: This is the final version before publication. The last page is an updated erratum for the published versio

Book Reviews

Book Reviews: Ha'ena: Through the Eyes of the Ancestors by Carlos Andrade ; Ben: A Memoir, From Street Kid to Governor by Benjamin J. Cayetano ; Asian Settler Colonialism: From Local Governance to the Habits of Everyday Life in Hawai'i edited by Candace Fujikane and Jonathan Y. Okamura ; Encyclopedia of Islands edited by Rosemary G. Gillespie and David A. Clague ; The Healthy Ancestor: Embodied Inequality and the Revitalization of Native Hawaiian Health by Juliet McMullin ; Alexander Cartwright: The Life Behind the Baseball Legend by Monica Nucciarone ; Island World: A History of Hawai'i and the United States by Gary Y. Okihiro ; A Japanese Robinson Crusoe by Jenichiro Oyabe and edited by Greg Robinson and Yujin Yaguchi ; A Tragedy of Democracy: Japanese Confinement in North America by Greg Robinso

Neodymium evidence for increased circumpolar deep water flow to the North Pacific during the Middle Miocene Climate Transition

Low salinity surface water inhibits local deepwater formation in the modern North Pacific. Instead, southern-sourced Circumpolar Deep Water (CDW) fills the basin, which is the product of water masses formed from cold sinking centers in the Southern Ocean and North Atlantic. This CDW is responsible for transporting a significant amount of global heat and dissolved carbon in the deep Pacific Ocean. The history of its flow and the broader overturning circulation are widely assumed to be sensitive to climate perturbations. However, insufficient records exist of CDW presence in the deep North Pacific with which to evaluate its evolution and role in major climate transitions of the past 23 Ma. Here we report sedimentary coatings and fish teeth neodymium isotope values—tracers for water-mass mixing—from deepwater International Ocean Discovery Program Site U1438 (4.7 km water depth) in the Philippine Sea, northwest Pacific Ocean. Our results indicate the water mass shifted from a North Pacific source in the early Miocene to a southern source by ~14 Ma. Within the age model and temporal constraints, this major reorganization of North Pacific water mass structure may have coincided with ice sheet build up on Antarctica and is most consistent with an increased northward flux ofCDWdue to enhanced sinking of cold water forced by Antarctic cooling. The northward extent of this flux may have remained relatively constant during much of the past 14Ma

Uniform selenization of crack-free films of Cu(In,Ga)Se2 nanocrystals

Crack-free films of Cu(In,Ga)Se2 (CIGS) nanocrystals were deposited with uniform thickness (>1 μm) on Mo-coated glass substrates using an ink-based, automated ultrasonic spray process, then selenized and incorporated into photovoltaic devices (PVs). The device performance depended strongly on the homogeneity of the selenized films. Cracks in the spray-deposited films resulted in uneven selenization rates and sintering by creating paths for rapid, uncontrollable selenium (Se) vapor penetration. To make crack-free films, the nanocrystals had to be completely coated with capping ligands in the ink. The selenization rate of crack-free films then depended on the thickness of the nanocrystal layer, the temperature, and duration of Se vapor exposure. Either inadequate or excessive Se exposure leads to poor device performance, generating films that were either partially sintered or exhibited significant accumulation of carbon and selenium. The deposition of uniform nanocrystal films is expected to be important for a variety of electronic and optoelectronic device applications.Fil: Harvey, Taylor B.. Texas A&M University; Estados UnidosFil: Bonafé, Franco Paúl. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Updegrave, Ty. University of Texas at Austin; Estados UnidosFil: Voggu, Vikas Reddy. University of Texas at Austin; Estados UnidosFil: Thomas, Cherrelle. University of Texas at Austin; Estados UnidosFil: Kamarajugadda, Sirish C.. University of Texas at Austin; Estados UnidosFil: Stolle, C. Jackson. University of Texas at Austin; Estados UnidosFil: Pernik, Douglas. University of Texas at Austin; Estados UnidosFil: Du, Jiang. University of Texas at Austin; Estados UnidosFil: Korgel, Brian A.. University of Texas at Austin; Estados Unido

Galileons as Wess-Zumino Terms

We show that the galileons can be thought of as Wess-Zumino terms for the spontaneous breaking of space-time symmetries. Wess-Zumino terms are terms which are not captured by the coset construction for phenomenological Lagrangians with broken symmetries. Rather they are, in d space-time dimensions, d-form potentials for (d+1)-forms which are non-trivial co-cycles in Lie algebra cohomology of the full symmetry group relative to the unbroken symmetry group. We introduce the galileon algebras and construct the non-trivial (d+1)-form co-cycles, showing that the presence of galileons and multi-galileons in all dimensions is counted by the dimensions of particular Lie algebra cohomology groups. We also discuss the DBI and conformal galileons from this point of view, showing that they are not Wess-Zumino terms, with one exception in each case.Comment: 49 pages. v2 minor changes, version appearing in JHE