1,721,089 research outputs found
Aviator Elly Beinhorn standing in front of a Klemm D-2160 aeroplane, 1932 [picture] /
No full textPart of collection: E.A. Crome collection of photographs on aviation.; Autograph in ink on top left.; Inscription: "Elly Beinhorn, Berlin-Sydney, 1931-1932, Klemm - D-2160"--Bottom right.; Title devised by cataloguer from inscription.; Also available in an electronic version via the Internet at: http://nla.gov.au/nla.pic-vn3723153; E.A. Crome collection relating to aviation in Australia, 1914-2005; located at; National Library of Australia Manuscript collection MS 1925
Supersymmetric near-horizon geometry and Einstein-Cartan-Weyl spaces
Full text linkWe show that the horizon geometry for supersymmetric black hole solutions of minimal five-dimensional gauged supergravity is that of a particular Einstein-Cartan-Weyl (ECW) structure in three dimensions, involving the trace and traceless part of both torsion and nonmetricity, and obeying some precise constraints. In the limit of zero cosmological constant, the set of nonlinear partial differential equations characterizing this ECW structure reduces correctly to that of a hyper-CR Einstein-Weyl structure in the Gauduchon gauge, which was shown by Dunajski, Gutowski and Sabra to be the horizon geometry in the ungauged BPS case
Einstein manifolds with torsion and nonmetricity
Full text linkManifolds endowed with torsion and nonmetricity are interesting both from the physical and the mathematical points of view. In this paper, we generalize some results presented in the literature. We study Einstein manifolds (i.e., manifolds whose symmetrized Ricci tensor is proportional to the metric) in d dimensions with nonvanishing torsion that has both a trace and a traceless part, and analyze invariance under extended conformal transformations of the corresponding field equations. Then, we compare our results to the case of Einstein manifolds with zero torsion and nonvanishing nonmetricity, where the latter is given in terms of the Weyl vector (Einstein-Weyl spaces). We find that the trace part of the torsion can alternatively be interpreted as the trace part of the nonmetricity. The analysis is subsequently extended to Einstein spaces with both torsion and nonmetricity, where we also discuss the general setting in which the nonmetricity tensor has both a trace and a traceless part. Moreover, we consider and investigate actions involving scalar curvatures obtained from torsionful or nonmetric connections, analyzing their relations with other gravitational theories that appeared previously in the literature. In particular, we show that the Einstein-Cartan action and the scale invariant gravity (also known as conformal gravity) action describe the same dynamics. Then, we consider the Einstein-Hilbert action coupled to a three-form field strength and show that its equations of motion imply that the manifold is Einstein with totally antisymmetric torsion
Elly Beinhorn following her solo flight in a Klemm D-2160 from Berlin to Newcastle Waters, Australia, March 1932 [picture] /
No full textInscription: "Elly Beinhorn, Solo flight Berlin - Newcastle Waters, March 1932, in Klemm D-2160"--In ink on image.; Part of collection: E.A. Crome collection of photographs on aviation.; Title devised by cataloguer from inscription and reference sources.; Also available in an electrionic version via the Internet at: http://nla.gov.au/nla.pic-vn3723156; E.A. Crome collection relating to aviation in Australia, 1914-2005; located at; National Library of Australia Manuscript collection MS 1925
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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