Gravitational Lensing in the Charged NUT-de Sitter Spacetime

It is a long-standing open question if a gravitomagnetic charge, the gravitational analogon to a hypothetical magnetic charge in electrodynamics, exists in nature. It naturally occurs in certain exact solutions to Einstein's electrovacuum-field equations with cosmological constant. The charged NUT-de Sitter metric is such a solution. It describes a black hole with electric and gravitomagnetic charges and a cosmological constant. In this paper we will address the question how we can observe the gravitomagnetic charge using gravitational lensing. For this purpose we first solve the equations of motion for lightlike geodesics using Legendre's canonical forms of the elliptic integrals and Jacobi's elliptic functions. We fix a stationary observer in the domain of outer communication and introduce an orthonormal tetrad. The orthonormal tetrad relates the direction under which the observer detects a light ray to its latitude-longitude coordinates on the observer's celestial sphere. In this parametrization we rederive the angular radius of the shadow, formulate a lens map, discuss the redshift, and the travel time. We also discuss relevant differences with respect to spherically symmetric and static spacetimes and how we can use them to determine if an astrophysical black hole has a gravitomagnetic charge.Comment: v2: 41 pages and 16 figures; all figures in very high resolution; adapted to match publish version (except format and minor details); minor postprint changes to fix nonessential typos; part of this work is extended to massive particles in arXiv:2304.1256

THE DEEP STRUCTURE OF AN ENNOVATTVE ACCOUNTING INFORMATION SYSTEM

For centuries accounting was the only formal information system in existence for business enterprises. Now accounting is often only a small part of an integrated information system. While numerous attempts have been made to clarify the exact structure of accounting, they have all been encumbered by past traditions that, while optimal under manual methods, did not do justice to accounting in a database environment. This paper shows how an informal model of accounting as movement of sand in a sandbox can be mapped to an ontologically complete financial accounting information system. Finally, the new model is contrasted with three competing models, and its implications for design and use of accounting information systems are discussed

Archaeology and Historical Ecology of Late Holocene San Miguel Island

California’s northern Channel Islands have one of the longest and best-preserved archaeological records in the Americas, spanning some 13,000 calendar years. When European explorers first traveled to the area, these islands were inhabited by the Chumash, some of the most populous and culturally complex hunter-gatherers known. Chumash society was characterized by hereditary leaders, sophisticated exchange networks and interaction spheres, and diverse maritime economies. Focusing on the archaeology of five sites dated to the last 3,000 years, this book examines the archaeology and historical ecology of San Miguel Island, the westernmost and most isolated of the northern Channel Islands. Detailed faunal, artifact, and other data are woven together in a diachronic analysis that investigates the interplay of social and ecological developments on this unique island. The first to focus solely on San Miguel Island archaeology, this book examines issues ranging from coastal adaptations to emergent cultural complexity to historical ecology and human impacts on ancient environments.Series: Perspectives in California Archaeology

Gravitational Lensing by Charged Accelerating Black Holes

Current astrophysical observations show that on large scale the Universe is electrically neutral. However, locally this may be quite different. Black holes enveloped by a plasma in the presence of a strong magnetic field may have acquired a significant electric charge. We can also expect that some of these charged black holes are moving. Consequently to describe them we need spacetime metrics describing moving black holes. In general relativity such a solution is given by the charged C-de Sitter-metric. In this article we will assume that it can be used to describe moving charged black holes. We will investigate how to observe the electric charge using gravitational lensing. First we will use elliptic integrals and functions to solve the geodesic equations. Then we will derive lens equation, travel time and redshift. We will discuss the impact of the electric charge on these observables and potential limitations for its observation.Comment: Submitted Conference Proceedings for 16th Marcel Grossmann Meeting, fixed typos/formulation

The Partisan Politics of New Social Risks in Advanced Postindustrial Democracies: Social Protection for Labor Market Outsiders

Advanced postindustrialization generates numerous challenges for the European social model. Central among these challenges is declining income, unstable employment, and inadequate training of semi- and unskilled workers. In this chapter, I assess the partisan basis of support for social policies that address the needs of these marginalized workers. I specifically consider the impacts of postindustrial cleavages among core constituencies of social democratic parties on the capacity of these parties to pursue inclusive social policies. I argue – and find support for in empirical analyses – that encompassing labor organization is the most important factor in strengthening the ability of left parties to build successful coalitions in support of outsider-friendly policies. I go beyond existing work on the topic by considering the full array of postindustrial cleavages facing left parties, by more fully elaborating why encompassing labor organization is crucial, and by considering a more complete set of measures of outsider policies than extant work. I compare my arguments and findings to important new work that stresses coalition building and partisan politics but minimizes the role of class organization

International transmission of transitory and persistent monetary shocks under imperfect information

We analyze the transmission of monetary shocks in a new openeconomy macroeconomics model with one-period nominal contracts and imperfect information. Shocks may have transitory and persistent components, which only through accumulation of information over time becomes known. Responses to shocks are altered compared to the case of full information. There are persistent effects on international relative prices, and delayed exchange-rate overshooting is possible following a persistent shock. In some cases, there are (ex post) excess returns as a positive interest rate spread is accompanied by an appreciating currency (or vice versa). Lastly, it is demonstrated that staggering re-inforce persistence

Propagation of nominal shocks in open economies

Empirical evidence documents substantial persistence in the adjustment process to nominal shocks. Existing open-economy models have failed either to generate interesting dynamics or found that the mechanisms are quantitatively weak. We consider the propagation of nominal shocks in a fully specified stochastic intertemporal open-economy model with incomplete capital markets and staggered nominal wage contracts. It is shown that persistence depends on wage-price interdependencies (spiral), which in turn in a general-equilibrium setting depends on structural parameters characterizing both the demand and the supply side of markets. Parameter choices strengthening wage-price interdependencies thus strengthen persistence as is demonstrated analytically and illustrated numerically. A further product of the paper is that it develops a method by which to solve explicitly for a stochastic intertemporal version of the New Open-Economy Macroeconomics model in which the expenditure switching effect is effective

Noisy Financial Signals and Persistent Effects of Nominal Shocks in Open Economies

Floating exchange rates display substantial short-run volatility causing a nontrivial information problem in disentangling temporary from permanent changes. Although agents observe current market signals they are imperfectly informed about the future, but they accumulate information and learn over time. We analyze how this basic information problem in the presence of one-period nominal contracts affects the dynamic adjustment process to nominal shocks. Specifically we use a general equilibrium two-country model with specialized production and one-period nominal contracts and consider the propagation of nominal shocks. Informational problems are shown to have important qualitative and potentially strong quantitative importance for the propagation of nominal shocks.