Eclipsing binary systems as tests of low-mass stellar evolution theory

Stellar fundamental properties (masses, radii, effective temperatures) can be extracted from observations of eclipsing binary systems with remarkable precision, often better than 2%. Such precise measurements afford us the opportunity to confront the validity of basic predictions of stellar evolution theory, such as the mass-radius relationship. A brief historical overview of confrontations between stellar models and data from eclipsing binaries is given, highlighting key results and physical insight that have led directly to our present understanding. The current paradigm that standard stellar evolution theory is insufficient to describe the most basic relation, that of a star's mass to its radius, along the main sequence is then described. Departures of theoretical expectations from empirical data, however, provide a rich opportunity to explore various physical solutions, improving our understanding of important stellar astrophysical processes.Comment: 9 pages, 2 figures. To appear in proceedings of "Living Together: Planets, Host Stars, and Binaries" convened in memory of Zdenek Kopa

Tagging mortality experiments on Pacific mackerel, Pneumatophorus japonicus

Two experiments were conducted to compare tagging mortality rates when Pacific mackerel are tagged using a traditional method and a modified method. Tagged and control fish in equal numbers were held in tanks on board the R/V ALASKA and observed for mortality. The experiments revealed mortality rates of 24% when the tag passes between the pterygiophores or neural spines and 1.5% when the tag is placed in the lateral musculature. Mortality from handling the fish for tagging was 4%, tank trauma was 2%, and the initial tag loss was 2.5%. (20pp.

Collapsing regions and black hole formation

Up to a conjecture in Riemannian geometry, we significantly strengthen a recent theorem of Eardley by proving that a compact region in an initial data surface that is collapsing sufficiently fast in comparison to its surface-to-volume ratio must contain a future trapped region. In addition to establishing this stronger result, the geometrical argument used does not require any asymptotic or energy conditions on the initial data. It follows that if such a region can be found in an asymptotically flat Cauchy surface of a spacetime satisfying the null-convergence condition, the spacetime must contain a black hole with the future trapped region therein. Further, up to another conjecture, we prove a strengthened version of our theorem by arguing that if a certain function (defined on the collection of compact subsets of the initial data surface that are themselves three-dimensional manifolds with boundary) is not strictly positive, then the initial data surface must contain a future trapped region. As a byproduct of this work, we offer a slightly generalized notion of a future trapped region as well as a new proof that future trapped regions lie within the black hole region.Comment: 11 pages, REVTeX 3.

A Case for Capacity Building: A Report on the High Desert's Fragile Social Services Infrastructure

Presents survey results from community organizations in California's High Desert region about governance, planning, marketing, program operations, funding, human resources, infrastructure, and the challenges they face in providing social services

The Core Virtue of Christian Librarianship

Christian librarians should derive their professional ethics from methodical exegesis of the Bible. The New Testament\u27s most salient ethical statements center on love-for God, neighbor, and fellow believers. Each of these has significant implications for library practice. Identifying love as the core virtue of librarianship represents a radical departure from secular approaches to library ethics. While the biblical and secular models converge on some significant points, they are fundamentally opposite. Where the two reach similar conclusions, the biblical model proves to be more philosophically consistent. The Scriptures speak with enduring relevance to the issues facing librarians