The genus spectrum of a hyperbolic 3-manifold

In this article we study the spectrum of totally geodesic surfaces of a finite volume hyperbolic 3-manifold. We show that for arithmetic hyperbolic 3-manifolds that contain a totally geodesic surface, this spectrum determines the commensurability class. In addition, we show that any finite volume hyperbolic 3-manifold has many pairs of non-isometric finite covers with identical spectra. Forgetting multiplicities, we can also construct pairs where the volume ratio is unbounded

Nonminimally coupled topological-defect boson stars: Static solutions

We consider spherically symmetric static composite structures consisting of a boson star and a global monopole, minimally or non-minimally coupled to the general relativistic gravitational field. In the non-minimally coupled case, Marunovic and Murkovic have shown that these objects, so-called boson D-stars, can be sufficiently gravitationally compact so as to potentially mimic black holes. Here, we present the results of an extensive numerical parameter space survey which reveals additional new and unexpected phenomenology in the model. In particular, focusing on families of boson D-stars which are parameterized by the central amplitude of the boson field, we find configurations for both the minimally and non-minimally coupled cases that contain one or more shells of bosonic matter located far from the origin. In parameter space, each shell spontaneously appears as one tunes through some critical central amplitude of the boson field. In some cases the shells apparently materialize at spatial infinity: in these instances their areal radii are observed to obey a universal scaling law in the vicinity of the critical amplitude. We derive this law from the equations of motion and the asymptotic behavior of the fields.Comment: 17 pages, 24 figure

The Bianchi groups are subgroup separable on geometrically finite subgroups

We show that for certain arithmetic groups, geometrically finite subgroups are the intersection of finite index subgroups containing them. Examples are the Bianchi groups and the Seifert-Weber dodecahedral space. In particular, for manifolds commensurable with these groups, immersed incompressible surfaces lift to embeddings in a finite sheeted covering.Comment: 19 page

Asymmetric Policy Interaction among Subnational Governments: Do States Play Welfare Games?

This paper explores the possibility that states respond asymmetrically to increases versus decreases in their neighboring states’ welfare benefit levels. We present a theoretical model suggesting that states respond more to decreases than to increases in their neighbors’ benefit levels. To test this proposition empirically, we use a panel of annual state-level data from 1983 to 1994 for each of the contiguous United States and the District of Columbia, and we observe changes in state demographic and economic characteristics as well as changes in state welfare benefits. We find substantial empirical evidence that uniformly supports our argument. State responses to neighbor benefit decreases tend to be at least twice as large as their responses to neighbor benefit increases. Our empirical results are robust to modeling neighbor benefits as endogenous. Our results, therefore, have substantial implications for public policy in the wake of the increased decentralization of welfare policy associated with the welfare reforms of 1996.

Studies on legume nodule bacteria: I. variations in strains of clover nodule bacteria; II. effects of calcium in media on clover module bacteria; III. nodule bacteria of various legumes of Scotland

For convenience of presentation the thesis has been divided into three sections -- I. Variation in Strains of Clover Nodule Bacteria; II. Effects of Calcium in Media on Clover Nodule Bacteria; and III. Nodule Bacteria of Various Legumes of Scotland. In the first is discussed certain aspects of clover inoculation and field and glasshouse trials of strains of legume organisms in both New Zealand and Scotland. The second covers work on the effects of culture media on characters and efficiency of strains of the clover organism. In the third section an outline is presented of the nodule organisms of Scottish legumes together with an analysis of the classification of nodule bacteria.The outbreak of war unfortunately necessitated a return to New Zealand before these studies were completed; with the result that certain phases of the work had to be finalized in the Dominion. While at Edinburgh the work was carried out under the direction of Professor T.J. Mackie and Dr. T. Gibson of the University of Edinburgh