Notes on Five-dimensional Kerr Black Holes

The geometry of five-dimensional Kerr black holes is discussed based on geodesics and Weyl curvatures. Kerr-Star space, Star-Kerr space and Kruskal space are naturally introduced by using special null geodesics. We show that the geodesics of AdS Kerr black hole are integrable, which generalizes the result of Frolov and Stojkovic. We also show that five-dimensional AdS Kerr black holes are isospectrum deformations of Ricci-flat Kerr black holes in the sense that the eigenvalues of the Weyl curvature are preserved.Comment: 23 pages, 5 figures; analyses on the Weyl curvature of AdS Kerr black holes are extended, an appendix and references are adde

The solubility and oxidation state of nickel in silicate melt at low oxygen fugacities: Results using a mechanically assisted equilibration technique

The solubility of Ni in a silicate melt has been measured using a new, mechanically assisted equilibration technique over a wide range of controlled ƒO2 values. The melt composition corresponds to the 1 atm eutectic in the system CaAl2Si2O8-CaMgSi2O6 + 10 wt% CaO. The experiments were performed at 1300°C and over an ƒO2 range of 10−8.5 to 10−13.75, and over a temperature range of 1270 to 1390°C at a constant gas mixing ratio ( ). The experiment consists of a sample of melt contained within a crucible of Ni metal and held in a 1 atm gas mixing furnace. A Ni spindle is entered into the sample from above and continuously rotated at a constant angular velocity using a viscometer head. The stirring of the sample serves to accelerate the approach to equilibrium between the liquid sample and the metal crucible (and spindle). This arrangement allows relatively rapid equilibration of Ni content following changes to higher or lower ƒO2 values. Samples of the melt may be taken at any time for analysis and thus the equilibrium solubility of Ni in the silicate melt may be determined from unambiguous experimental reversals. The Ni contents of samples, analysed both by INAA and by ICP-AES, range from 25 to 5300 ppm. The data presented in this paper indicate that the oxidation state of Ni in the investigated melt is Ni2+ over the entire range of ƒO2 investigated. This conclusion contrasts with recent reports in the literature of an inflection in the ƒO2 dependence of Ni solubility, which has been interpreted as solution of neutral Ni at low ƒO2 (Morse et al., 1991; Colson, 1992; Ehlers et al., 1992). We also present data for the temperature dependence of Ni solubility in the investigated melt. The solubility decreases with increasing temperature at constant ƒO2. The present results are in good agreement with the metal-loop-equilibration experiments reported by Holzheid et al. (1994)

The solubility of rhenium in silicate melts: Implications for the geochemical properties of rhenium at high temperatures

The solubility of rhenium (Re) in a haplobasaltic melt (anorthite-diopside eutectic composition) has been experimentally determined using the mechanically assisted equilibration technique at 1400°C as a function of oxygen fugacity (10−12 < fO2 ≤ 10−7 bar), imposed by CO-CO2 gas mixtures. Samples were analysed by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). This is a true microanalytical technique, which allows small-scale sample heterogeneity to be detected, while providing a limit of detection of 2 ppb Re. Time-resolved LA-ICP-MS spectra revealed the presence of suboptically sized micronuggets of Re in all samples, which, because they are present at the 0.5 to 10 ppm level, dominate the true solubilities of Re (<1 ppm at the conditions of the experiment) in bulk analyses of the samples. Nevertheless, the micronuggets could be filtered out from the time-resolved spectra to reveal accurate values of the true Re solubility. A number of time series of samples were taken at constant fO2 to demonstrate that the solubilities converge to a constant value. In addition, solubilities were measured after increasing and decreasing the imposed fO2. The results show that Re dissolves in the silicate melt as ReO2 (Re4+) and ReO3 (Re6+) species, with the latter predominating at typical terrestrial upper-mantle oxygen fugacities. The total solubility of Re is described by the following expression (fO2 in bars): [Re/ppb] = 9.7(±1.9) × 109 (fO2) + 4.2 (±0.3) × 1014 (fO2)1.5Assuming an activity coefficient for Re in Fe-rich metal of 1, this gives a value of DRemet/sil of 5 × 1010 at log fO2 = IW-2, appropriate for metal-silicate partitioning in an homogenously accreting Earth. Thus, Re is indeed very highly siderophile, and the mantle’s abundance cannot be explained by homogenous accretion

Culinary resistance?

Can James C. Scott’s model of resistance be extended to the field of cuisine? To what extent can a group resist through food and cooking? This paper poses these two queries within the context of a Malaysian foodscape: the Kristangs, or Portuguese Eurasians, of polyethnic Malacca. A series of cultural 'worlds' has architectured this multicultural Creole group and includes Indian, Chinese, and Malay worlds in action prior to the arrival of Portuguese colonos in 1511, as well as the later Dutch and British colonial regimes. By simply persisting, or enduring, the group is also resisting; cuisine comprises a key element in this persistence. By sidestepping the dominant/dominated lens, we can focus more clearly on the group’s positive strategies of resistance through cooking. One major implication for Action Theory is that they have practiced the Art of Resisting via the Art of Persisting.info:eu-repo/semantics/publishedVersio

The Energy-Momentum tensor on SpincSpin^c manifolds

On $Spin^c$ manifolds, we study the Energy-Momentum tensor associated with a spinor field. First, we give a spinorial Gauss type formula for oriented hypersurfaces of a $Spin^c$ manifold. Using the notion of generalized cylinders, we derive the variationnal formula for the Dirac operator under metric deformation and point out that the Energy-Momentum tensor appears naturally as the second fundamental form of an isometric immersion. Finally, we show that generalized $Spin^c$ Killing spinors for Codazzi Energy-Momentum tensor are restrictions of parallel spinors.Comment: To appear in IJGMMP (International Journal of Geometric Methods in Modern Physics), 22 page

Taking General Education Seriously: Expanding The Boundary Of A Principles Of Macroeconomics Course

Does teaching a course that “counts” for general education credit carry with it any responsibilities beyond discipline content? How might you entice students to view a discipline specific course in more general terms? What might be done to link a course in one discipline to courses in related disciplines so that students see connections? These are some of the questions that I have been attempting to answer within the context of a Principles of Macroeconomics course at the University of North Dakota. This paper describes two initiatives undertaken over the past two years. The first initiative occurred during the Spring 2003 semester within two sections of Principles of Macroeconomics. In one section students were given a traditional lecture-based course. In the other section, in addition to lectures, students were asked to read, think about, discuss, and write about how economics relates to other disciplines and how economic thinking might be applied when examining issues beyond economics. The main vehicle used for this latter aspect of the course was to have the students explore the book Dollars and Change: Economics In Context by Louis Putterman. The second initiative took place during the Spring 2004 semester. During this semester, within two sections of Principles of Macroeconomics, all students were asked to read, think about, discuss, and write about general education (liberal learning). The main vehicle used for this initiative was to have the students explore the book A Student’s Guide to Liberal Learning by James V. Schall and the description of general education in the University catalog. A detailed description of each of these two initiatives is provided, including copies of assignment sheets and grading rubrics. A discussion of the outcomes of each of these initiatives is presented, from the perspective of the students as well as of the faculty member. The analysis presented is primarily qualitative

Practice theory in practice: critical anthropology in Galicia and Portugal in the 1970s

What links are there between feldwork sites and the specifc authors, texts, and theories which inspired the ethnographer before and after the stint? Here are some retrospective meanderings on two terrains studied in the 1970s – the Caurel mountains in eastern Galicia and north-eastern Trás-os-Montes in Portugal. Neither of these places seemed to ft anywhere within the expansive British anthropology of the Mediterranean dominant throughout that decade. These hamlets certainly looked nothing like minuscule, egalitarian rural paradises. Dual family structures, complex household dynamics, asymmetrical labour exchanges, alternative marriages, and rampant bastardy required a radically different analysis. Inspiration came from Goody’s comparative sociology of Eurasian inheritance strategies and Bourdieu’s practice theory. My earlier undergraduate work on realist literature and descriptive dissection now heard – following the feldwork itself – a loud echo. Both Goody’s and Bourdieu’s rebel and pervasive hyper-critical spirits provided the spark.info:eu-repo/semantics/publishedVersio

Remarks on the Reeh-Schlieder property for higher spin free fields on curved spacetimes

The existence of states enjoying a weak form of the Reeh-Schlieder property has been recently established on curved backgrounds and in the framework of locally covariant quantum field theory. Since only the example of a real scalar field has been discussed, we extend the analysis to the case of massive and massless free fields either of spin 1/2 or of spin 1. In the process, it is also shown that both the vector potential and the Proca field can be described as a locally covariant quantum field theory.Comment: 28 pages, references and remarks added, typos correcte