28,129 research outputs found

    Very Extended E8E_8 and A8A_8 at low levels, Gravity and Supergravity

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    We define a level for a large class of Lorentzian Kac-Moody algebras. Using this we find the representation content of very extended AD−3A_{D-3} and E8E_8 (i.e. E11E_{11}) at low levels in terms of AD−1A_{D-1} and A10A_{10} representations respectively. The results are consistent with the conjectured very extended A8A_8 and E11E_{11} symmetries of gravity and maximal supergravity theories given respectively in hep-th/0104081 and hep-th/0107209. We explain how these results provided further evidence for these conjectures.Comment: 16 pages, plain tex (equation 3.3 modified and one reference expanded

    Generalised geometry, eleven dimensions and E11

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    We construct the non-linear realisation of E11 and its first fundamental representation in eleven dimensions at low levels. The fields depend on the usual coordinates of space-time as well as two form and five form coordinates. We derive the terms in the dynamics that contain the three form and six form fields and show that when we restricted their field dependence to be only on the usual space-time we recover the correct self-duality relation. Should this result generalise to the gravity fields then the non-linear realisation is an extension of the maximal supergravity theory, as previously conjectured. We also comment on the connections between the different approaches to generalised geometry.Comment: 17 pages, Trivial typos corrected in version one and a substantial note added which gives the equation of motion relating the gravity field to its dua

    How the Cervical Microbiota Contributes to Cervical Cancer Risk in Sub-Saharan Africa

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    Despite ongoing efforts, sub-Saharan Africa faces a higher cervical cancer burden than anywhere else in the world. Besides HPV infection, definitive factors of cervical cancer are still unclear. Particular states of the cervicovaginal microbiota and viral infections are associated with increased cervical cancer risk. Notably, HIV infection, which is prevalent in sub-Saharan Africa, greatly increases risk of cervicovaginal dysbiosis and cervical cancer. To better understand and address cervical cancer in sub-Saharan Africa, a better knowledge of the regional cervicovaginal microbiome is required This review establishes current knowledge of HPV, HIV, cervicovaginal infections, and the cervicovaginal microbiota in sub-Saharan Africa. Because population statistics are not available for the region, estimates are derived from smaller cohort studies. Microbiota associated with cervical inflammation have been found to be especially prevalent in sub-Saharan Africa, and to associate with increased cervical cancer risk. In addition to high prevalence and diversity of HIV and HPV, intracellular bacterial infections such as Chlamydia, Gonorrhea, and Mycoplasma hominis are much more common than in regions with a low burden of cervical cancer. This suggests the prevalence of cervical cancer in sub-Saharan Africa may be partially attributed to increased cervical inflammation resulting from higher likelihood of cervical infection and/or microbial dysbiosis

    An anatomical study of additional radial wrist extensors including a unique extensor carpi radialis accessorius

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    Background: In this study, 82 forearms from 41 cadavers were dissected to establish the incidence of variant additional radial wrist extensors. Three variants have been described in the literature: extensor carpi radialis intermedius (ECRI), extensor carpi radialis accessorius (ECRA) and extensor carpi radialis tertius (ECRT). Materials and methods: Of the 41 cadavers studied, 5/41 (12%) had an additional radial wrist extensor. Of these 5 individuals, 2 had bilateral additional muscles and 3 were unilateral. Of the 82 forearms, 7/82 (9%) had additional radial wrist extensors. Results: We found 4 examples of ECRI and 3 examples of ECRA. We did not find any examples of ECRT. One specimen of ECRA had an atypical, previously undescribed, course. Conclusions: These accessory muscles are of clinical relevance, as they may be a contributing factor in tennis elbow and nerve entrapment, or cause diagnostic confusion, especially in ultrasound scans. However, they may also be used for tendon transfer. Of the 7 muscles found in the current study, 3 would have been suitable for such procedures.

    Voles: Wildlife Damage Management Series

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    Duality Symmetries and G^{+++} Theories

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    We show that the non-linear realisations of all the very extended algebras G^{+++}, except the B and C series which we do not consider, contain fields corresponding to all possible duality symmetries of the on-shell degrees of freedom of these theories. This result also holds for G_2^{+++} and we argue that the non-linear realisation of this algebra accounts precisely for the form fields present in the corresponding supersymmetric theory. We also find a simple necessary condition for the roots to belong to a G^{+++} algebra.Comment: 35 pages. v2: 2 appendices added, other minor corrections. v3: tables corrected, other minor changes, one appendix added, refs. added. Version published in Class. Quant. Gra

    The Fragmenting Superbubble Associated with the HII Region W4

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    New observations at high latitudes above the HII region W4 show that the structure formerly identified as a chimney candidate, an opening to the Galactic halo, is instead a superbubble in the process of fragmenting and possibly evolving into a chimney. Data at high Galactic latitudes (b > 5 degrees) above the W3/W4 star forming region at 1420 and 408 MHz Stokes I (total power) and 1420 MHz Stokes Q and U (linear polarization) reveal an egg-shaped structure with morphological correlations between our data and the H-alpha data of Dennison, Topasna, & Simonetti. Polarized intensity images show depolarization extending from W4 up the walls of the superbubble, providing strong evidence that the radio continuum is generated by thermal emission coincident with the H-alpha emission regions. We conclude that the parts of the HII region hitherto known as W4 and the newly revealed thermal emission are all ionized by the open cluster OCl 352. Assuming a distance of 2.35 kpc, the ovoid structure is 164 pc wide and extends 246 pc above the mid-plane of the Galaxy. The shell's emission decreases in total-intensity and polarized intensity in various locations, appearing to have a break at its top and another on one side. Using a geometric analysis of the depolarization in the shell's walls, we estimate that a magnetic field line-of-sight component of 3 to 5 uG exists in the shell. We explore the connection between W4 and the Galactic halo, considering whether sufficient radiation can escape from the fragmenting superbubble to ionize the kpc-scale H-alpha loop discovered by Reynolds, Sterling & Haffner.Comment: 42 pages, 14 figures; Accepted for publication in Ap

    The local symmetries of M-theory and their formulation in generalised geometry

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    In the doubled field theory approach to string theory, the T-duality group is promoted to a manifest symmetry at the expense of replacing ordinary Riemannian geometry with generalised geometry on a doubled space. The local symmetries are then given by a generalised Lie derivative and its associated algebra. This paper constructs an analogous structure for M-theory. A crucial by-product of this is the derivation of the physical section condition for M-theory formulated in an extended space.Comment: 20 pages, v2: Author Name corrected, v3: typos correcte

    Evolutionary theory and the ultimate-proximate distinction in the human behavioral sciences

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    To properly understand behavior, we must obtain both ultimate and proximate explanations. Put briefly, ultimate explanations are concerned with why a behavior exists, and proximate explanations are concerned with how it works. These two types of explanation are complementary and the distinction is critical to evolutionary explanation. We are concerned that they have become conflated in some areas of the evolutionary literature on human behavior. This article brings attention to these issues. We focus on three specific areas: the evolution of cooperation, transmitted culture, and epigenetics. We do this to avoid confusion and wasted effort—dangers that are particularly acute in interdisciplinary research. Throughout this article, we suggest ways in which misunderstanding may be avoided in the future
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