Isotropy, shear, symmetry and exact solutions for relativistic fluid spheres

The symmetry method is used to derive solutions of Einstein's equations for fluid spheres using an isotropic metric and a velocity four vector that is non-comoving. Initially the Lie, classical approach is used to review and provide a connecting framework for many comoving and so shear free solutions. This provides the basis for the derivation of the classical point symmetries for the more general and mathematicaly less tractable description of Einstein's equations in the non-comoving frame. Although the range of symmetries is restrictive, existing and new symmetry solutions with non-zero shear are derived. The range is then extended using the non-classical direct symmetry approach of Clarkson and Kruskal and so additional new solutions with non-zero shear are also presented. The kinematics and pressure, energy density, mass function of these solutions are determined.Comment: To appear in Classical and Quantum Gravit

Increased Bufflehead (Bucephala albeola) Breeding Activity in Minnesota

Buffleheads (Bucephala albeola) predominantly nest in the boreal forests and aspen parklands of Canada and Alaska. Historically, Buffleheads were common migrants but not summer residents in Minnesota. However, recent observations in Minnesota and surrounding states suggest increased breeding activity in the region. In 1978, the first Bufflehead brood in Minnesota was recorded at East Park Wildlife Management Area. Annually, Agassiz National Wildlife Refuge (NWR) has conducted pair and brood surveys, with species-specific records available from 1990 to 2014. We report an increase in numbers of Bufflehead breeding pairs and broods at Agassiz NWR and new pair observations in surrounding areas

A Community of Procedure Scholars: Teaching Procedure and the Legal Academy

This article asks whether the way in which procedure is taught has an impact on the extent and accomplishments of a scholarly community of proceduralists. Not surprisingly, we find a strong correlation between the placement of procedure as a required course in an academic context and the resulting body of scholars and scholarship. Those countries in which more civil procedure is taught as part of a university degree — and in which procedure is recognized as a legitimate academic subject — have larger scholarly communities, a larger and broader corpus of works analyzing procedural issues, and a richer web of institutional support systems that inspire, fund, and shape the study of public justice

Invariant construction of solutions to Einstein's field equations - LRS perfect fluids II

The properties of LRS class II perfect fluid space-times are analyzed using the description of geometries in terms of the Riemann tensor and a finite number of its covariant derivatives. In this manner it is straightforward to obtain the plane and hyperbolic analogues to the spherical symmetric case. For spherically symmetric static models the set of equations is reduced to the Tolman-Oppenheimer-Volkoff equation only. Some new non-stationary and inhomogeneous solutions with shear, expansion, and acceleration of the fluid are presented. Among these are a class of temporally self-similar solutions with equation of state given by $p=(\gamma-1)\mu, 1<\gamma<2$, and a class of solutions characterized by $\sigma=-\Theta/6$. We give an example of geometry where the Riemann tensor and the Ricci rotation coefficients are not sufficient to give a complete description of the geometry. Using an extension of the method, we find the full metric in terms of curvature quantities.Comment: 24 pages, 1 figur

Modeling the target strength of Meganyctiphanes norvegica

Abstract only. Journal home page: http://scitation.aip.org/jasa

The Stability of an Isentropic Model for a Gaseous Relativistic Star

We show that the isentropic subclass of Buchdahl's exact solution for a gaseous relativistic star is stable and gravitationally bound for all values of the compactness ratio $u [\equiv (M/R)$, where $M$ is the total mass and $R$ is the radius of the configuration in geometrized units] in the range, $0 < u \leq 0.20$, corresponding to the {\em regular} behaviour of the solution. This result is in agreement with the expectation and opposite to the earlier claim found in the literature.Comment: 9 pages (including 1 table); accepted for publication in GR

Initial collateral measurements of some properties of Calanus finmarchicus

In general, acoustic quantification of zooplankton such as Calanus finmarchicus requires the use of models, among other reasons, to aid in the interpretations of data collected on animals whose scattering properties change with development stage, season, and other environmentally linked factors. In conjunction with a project to determine acoustic scattering signatures of zooplankton and fish, a study is being performed to measure physical, morphometric, and biochemical properties of selected euphausiid species and Calanus finmarchicus. An important feature of this study is the performance of a suite of measurements on animals collected at the same time and place. The measurement methods being used to study Calanus are presented here together with results from the initial field experiment. The criticism of interested parties is solicited