180,492 research outputs found
F (R, Rμν2) at one loop
No full textWe compute the one-loop divergences in a theory of gravity with a Lagrangian of the general form f(R,RμνRμν), on an Einstein background. We also establish that the one-loop effective action is invariant under a duality that consists of changing certain parameters in the relation between the metric and the quantum fluctuation field. Finally, we discuss the unimodular version of such a theory and establish its equivalence at one-loop order with the general case
Production of poly(B-hydroxyalkanoate)s by bacteria strains and transconjugant strains in biphase cultivation.
No full textT. Ohta and T. Homma (eds.), ", Univ. Acad. Press, F.S.S
Flow equation for f(R) gravity and some of its exact solutions
No full textWe write a Renormalization Group (RG) equation for the function f in a theory of gravity in the f(R) truncation. Our equation differs from previous ones due to the exponential parametrization of the quantum fluctuations and to the choice of gauge. The cutoff procedure depends on three free parameters, and we find that there exist discrete special choices of parameters for which the flow equation has fixed points where f=f_0+f_1 R+f_2 R^2. For other values of the parameters the solution seems to be continuously deformed
Renormalization group equation and scaling solutions for () gravity in exponential parametrization
No full textWe employ the exponential parametrization of the metric and a “physical” gauge fixing procedure to write a functional flow equation for the gravitational effective average action in an f(R) truncation. The background metric is a four-sphere and the coarse-graining procedure contains three free parameters. We look for scaling solutions, i.e. non-Gaussian fixed points for the function f. For a discrete set of values of the parameters, we find simple global solutions of quadratic polynomial form. For other values, global solutions can be found numerically. Such solutions can be extended in certain regions of parameter space and have two relevant directions. We discuss the merits and the shortcomings of this procedure. © 2016, The Author(s)
Binding Energy between a Vacancy and an Atom of Third Element and their Effects on the Initial Aging of Aluminium Binary Alloys
No full textAl-Zn, Al-Ag and Al-Cu base ternary alloys were studied by measurement of electrical resistivity. An approximate methods to estimate the binding energy between an atom of a third element and a vacancy was derived. The binding energy between a vacancy and an atom of Cu, Ag, Au, Be, Ca, Cd, In, Si, Ti, Ge, Zr, Sn, Pb or Mn was estimated to be 0.35, 0.28, 0.27, 0.32, 0.39, 0.28, 0.30, 0.33, 0.33, 0.43, >0.38 or <0.23 (±0.05) eV, respectively. The results may be summarized as follows: (I) The ratio of the time required to reach the maximum electrical resistivity in isothermal aging curves of the Al-Zn-X or Al-Ag-X ternary alloy to that in the Al-Zn or Al-Ag binary alloy may be inversely proportional to the ratio of the concentration of vacancies bound to Zn or Ag atoms immediately after quenching in the ternary alloy to that in the binary alloy. And also the ratio of initial rate of clustering for AI-Cu-X ternary alloy to that in the binary alloy may be inversely proportional to the ratio of the concentration of vacancies bound to Cu atoms immediately after quenching in the ternary alloy to that in the binary alloy. It is possible to deduce the binding energy
between an atom of X element and a vacancy using this relations. (2) The effect of the valence of the solute element on the binding energy between an atom of a third element and a vacancy was remarkable. (3) The effect of the radius of an atom of the solute element on the binding energy is also observed, but this effect is smaller than that of the valence
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Path integral of unimodular gravity
No full textWe compute the one-loop effective action in unimodular gravity, starting from two different classical formulations of the theory. We find that the effective action is the same in both cases, and agrees with the one of general relativity
Gauges and functional measures in quantum gravity II: higher-derivative gravity
No full textWe compute the one-loop divergences in a higher-derivative theory of gravity including Ricci tensor squared and Ricci scalar squared terms, in addition to the Hilbert and cosmological terms, on an (generally off-shell) Einstein background. We work with a two-parameter family of parametrizations of the graviton field, and a two-parameter family of gauges. We find that there are some choices of gauge or parametrization that reduce the dependence on the remaining parameters. The results are invariant under a recently discovered “duality” that involves the replacement of the densitized metric by a densitized inverse metric as the fundamental quantum variable
Fumi Kato Tanaka, Yasuko Kato Ohta, Amy Iwaki, Amy\u27s brother, and Jack Aoyagi kneeling in front of a car (L-R)
No full textPhoto of several Japanese American friends of Mary (Murakami) Doi, probably in Salt Lake City in the 1940s. Individuals are (L-R): Fumi Kato Tanaka, Yasuko Kato Ohta, Amy Iwaki, Amy\u27s brother, and Jack Aoyagi kneeling in front of a car
Towards the determination of the dimension of the critical surface in asymptotically safe gravity
No full textWe compute the beta functions of Higher Derivative Gravity within the Functional Renormalization Group approach, going beyond previously studied approximations. We find that the presence of a nontrivial Newtonian coupling induces, in addition to the free fixed point of the one-loop approximation, also two nontrivial fixed points, of which one has the right signs to be free from tachyons. Our results are consistent with earlier suggestions that the dimension of the critical surface for pure gravity is three
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