86,780 research outputs found
Yb9+xCuMg4x (x = 0.034): A Phase Formed by Lanthanoids
No full textAtom order in the crystal structures of Yb2Cu2-xMg (x = 0.17; Mo2FeB2-type; P4/mbm; a = 0.75592(2) nm; c = 0.40282(1) nm) and Yb9 + xCuMg4 - x (x = 0.034; Hf9Mo4B-type; P63/mmc; a = 1.0169(5) nm; c = 1.0290(5) nm) was determined from powder and X-ray single-crystal counter data analyses supported by electron probe microanalyses. Among the group of the so-called κ -phases, Yb9 + xCuMg4 - x is the first representative formed by a lanthanoid element. The structure of this κ -phase can be viewed as a typical network of corner-connected empty Yb6-octahedra, which encompass Yb6Mg6-icosahedra (filled by a mix of Mg/Yb atoms) and Yb6-trigonal prisms centered by Cu atoms to complete the three-dimensional metal framework. From another point of view, the same structure is considered as built from in finite polyicosahedral columns of Yb9Mg4 composition with Cu atoms located in trigonal prismatic interstices, highlighting similarities with other Yb-rich Yb−Cu−Mg phases. Density functional theory (DFT) calculations classify Yb9CuMg4 as a polar intermetallic. Metallic-like behavior is inferred from the Sommerfeld constant, γ = 49.2 mJ/molK2, derived from the electronic density of states, calculated at the Fermi level. DFT integration of the f-density of states indicates almost completely filled f-states, revealing 13.6 and 13.7 electrons in the valence band for Yb1 and Yb2 atoms, respectively, close to the Yb2+ ground state (1S0) for both Yb atoms. Magnetic susceptibility data recorded on the same compound are consistent with a nonmagnetic divalent Yb2+ state. Temperature-dependent heat capacity data display a metallic behavior characterized by a small Sommerfeld constant γ = 64.8 mJ/molK2 and a rather low Debye temperature ΘD = 140 K as typical for soft materials
Principal Bundles and Gauge Theories
No full textThis set of lecture notes fills a hole that in the authors opinion currently exists in the available literature on (prequantum or first quantised) gauge theory: theoretical physics texts do lots of calculations in coordinates and fail to appreciate the underlying geometry of their equations; mathematics texts develop the geometric theory of fibre bundles in its full abtract glory, but, in their attempt to keep things abstract, completely miss out on describing fascinating physical interpretations of their mathematical objects.
In these notes, the mathematical theory of fibre bundles is built up from the ground in great generality, slowly adding more structure and converging to the structures we see in modern physics. At this point, we are in the perfect position to fit some modern theories of physics in the framework.
This unconventional exposition of the material can hopefully shed new light on the topic for both mathematicians and physicists, serving as a brief introduction to the other discipline's point of view
Curvature weighted metrics on shape space of hypersurfaces in n-space
No full textAbstractLet M be a compact connected oriented (n−1)-dimensional manifold without boundary. In this work, shape space is the orbifold of unparametrized immersions from M to Rn. The results of M. Bauer, P. Harms, P.W. Michor (2001) [1] where mean curvature weighted metrics were studied, suggest incorporating Gauß curvature weights in the definition of the metric. This leads us to study metrics on shape space that are induced by metrics on the space of immersions of the formGf(h,k)=∫MΦ.g¯(h,k)vol(f⁎g¯). Here f∈Imm(M,Rn) is an immersion of M into Rn and h,k∈C∞(M,Rn) are tangent vectors at f. g¯ is the standard metric on Rn, f⁎g¯ is the induced metric on M, vol(f⁎g¯) is the induced volume density and Φ is a suitable smooth function depending on the mean curvature and Gauß curvature. For these metrics we compute the geodesic equations both on the space of immersions and on shape space and the conserved momenta arising from the obvious symmetries. Numerical experiments illustrate the behavior of these metrics
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
[Newspaper Clipping: Author Claims Evidence of Second JFK Assassin #1]
No full textNewspaper article titled "Author Claims Evidence of Second JFK Assassin." The article states that author Richard J. Whalen concluded "that there is circumstantial evidence to support the theory of a second assassin in the shooting of President John F. Kennedy.
Structural Phase Transition and Magnetic Anisotropy of La substituted M-Type Sr Hexaferrite
No full textAlso By The Same Author: AKTiveAuthor, a Citation Graph Approach to Name Disambiguation
No full textThe desire for definitive data and the semantic web drive for inference over heterogeneous data sources requires co-reference resolution to be performed on those data. In particular, name disambiguation is required to allow accurate publication lists, citation counts and impact measures to be determined. This paper describes a graph-based approach to author disambiguation on large-scale citation networks. Using self-citation, co-authorship and document source analyses, AKTiveAuthor clusters papers, achieving precision of 0.997 and recall of 0.818 over a test group of eight surname clusters
John F. Kennedy telegram to Roosevelt
No full textJersey Homesteads (later the Borough of Roosevelt) was established in the 1930s as an agro-industrial cooperative community. It was established specifically for urban Jewish garment workers, many of whom had emigrated from Europe. President John F. Kennedy sent a telegram to the citizens of Roosevelt, New Jersey, apologizing for not being able to attend the memorial dedication in honor of former President Franklin Delano Roosevelt. (Jersey Homesteads became Roosevelt in 1945 in honor of the president.) President Kennedy expressed his gratitude to the people of Roosevelt for constructing the memorial, and commented that it will serve as a constant reminder of Roosevelt's good works
Logarithmic variance profiles and the corresponding f-1 spectra of temperature fluctuations in turbulent Rayleigh-Bénard convection
No full textWe report experimental results for the temperature variance 2(z) and the corresponding frequency spectra P(f) in turbulent Rayleigh-Bénard convection (RBC) in a cylindrical sample of aspect ratioT= D/L = 1:00 (D = 1:12 m is the diameter and L = 1:12 m the height). The measurements were conducted in the Rayleigh-number range 1011 < Ra < 1:35 1014 and Pr ' 0:8. For Ra = 1:35x1014, 2(z) could be described well by a logarithmic dependence on the vertical position z in a range of z 1 < z < z 2 with z 1 ' 70 and z 2 = 0:1L. Here L=(2Nu) is the thickness of a thin thermal sublayer adjacent to the horizontal plate where the heat flux (denoted by the Nusselt number Nu) is carried mostly by thermal diffusion. In the log layer, we found that the temperature spectra had a significant frequency range over which P(f) f with close to 1. As Ra decreased, increased so that the log layer became thinner. At Ra = 2:05 1011, z 2 < z 1 and therefore there was no range for a log layer. Correspondingly, the temperature spectrum near the horizontal plate did not have the f1 scaling form either
Maine author Franklin F. Gould recalls his first glimpse of the outside world
No full textMaine author Franklin F. Gould recalls his first glimpse of the outside world as he relates how, as a young farm boy in the late 1800\u27s, he drove his father\u27s horses on an errand to an icebound river
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