Spinning Down a Black Hole With Scalar Fields

We study the evolution of a Kerr black hole emitting scalar radiation via the Hawking process. We show that the rate at which mass and angular momentum are lost by the black hole leads to a final evolutionary state with nonzero angular momentum, namely $a/M \approx 0.555$.Comment: 4 pages (including 3 postscript figures), Revtex, uses epsf.tex, twocolumn.sty and header.sty (included). Submitted to Physical Review Letter

Independent Domestication of Two Old World Cotton Species

Domesticated cotton species provide raw material for the majority of the world\u27s textile industry. Two independent domestication events have been identified in allopolyploid cotton, one in Upland cotton ( Gossypium hirsutum L.) and the other to Egyptian cotton ( Gossypium barbadense L.). However, two diploid cotton species, Gossypium arboreum L. and Gossypium herbaceum L., have been cultivated for several millennia, but their status as independent domesticates has long been in question. Using genome resequencing data, we estimated the global abundance of various repetitive DNAs. We demonstrate that, despite negligible divergence in genome size, the two domesticated diploid cotton species contain different, but compensatory, repeat content and have thus experienced cryptic alterations in repeat abundance despite equivalence in genome size. Evidence of independent origin is bolstered by estimates of divergence times based on molecular evolutionary analysis of f7,000 orthologous genes, for which synonymous substitution rates suggest that G. arboreum and G. herbaceum last shared a common ancestor approximately 0.4–2.5 Ma. These data are incompatible with a shared domestication history during the emergence of agriculture and lead to the conclusion that G. arboreum and G. herbaceum were each domesticated independently

Self-interest And Public Interest: The Motivations Of Political Actors

Self-Interest and Public Interest in Western Politics showed that the public, politicians, and bureaucrats are often public spirited. But this does not invalidate public-choice theory. Public-choice theory is an ideal type, not a claim that self-interest explains all political behavior. Instead, public-choice theory is useful in creating rules and institutions that guard against the worst case, which would be universal self-interestedness in politics. In contrast, the public-interest hypothesis is neither a comprehensive explanation of political behavior nor a sound basis for institutional design

Do Child Soldiers Influence UN Peacekeeping?

The use of child soldiers in conflicts has received increasing academic attention in recent years. This article examines post-conflict periods to see whether the use of child soldiers mobilizes United Nations peacekeeping operations (UN PKO) in the aftermath of a conflict. Taking into consideration how child soldiers affect conflict and how important their reintegration is to sustainable peace and post-conflict development, we analyse whether the presence of child soldiers in a civil war increases the likelihood of the presence of a PKO. We argue that the UN deems a conflict with child soldiers as a difficult case for conflict resolution, necessitating a response from the international community. This is in line with our empirical results confirming that the use of child soldiers significantly increases the likelihood of peacekeeping

Components of Effective Leadership

[First paragraph] The effective schools literature demonstrates that the principal\u27s leadership is key to the revitalization of schools. The purpose of this article is to feature those components of leadership on which principals need to place attention and to provide suggested activities to enhance these components

Leadership Styles

[First paragraph] Effective schools literature shows clearly that the leadership of the principal is key to the effectiveness of the school (Hoy and Miskell, 1982, and Arnn and Mangieri, 1988). To be effective, principals must use leadership styles appropriate to the situation

Semiclassical effects in black hole interiors

First-order semiclassical perturbations to the Schwarzschild black hole geometry are studied within the black hole interior. The source of the perturbations is taken to be the vacuum stress-energy of quantized scalar, spinor, and vector fields, evaluated using analytic approximations developed by Page and others (for massless fields) and the DeWitt-Schwinger approximation (for massive fields). Viewing the interior as an anisotropic collapsing cosmology, we find that minimally or conformally coupled scalar fields, and spinor fields, decrease the anisotropy as the singularity is approached, while vector fields increase the anisotropy. In addition, we find that massless fields of all spins, and massive vector fields, strengthen the singularity, while massive scalar and spinor fields tend to slow the growth of curvature.Comment: 29 pages, ReVTeX; 4 ps figure

Grievances

[First Paragraph] The Virginia Board of Education has adopted a procedure for resolving disputes concerning the application of local board policies, rules, and regulations as they impact the work or disciplinary actions of teachers. It is vital that the principal be aware of the process and the timeline involved in the grievance procedure since the solution should be secured at the lowest administrative level in the process. It is beyond the scope of this article to provide every detail of the grievance process. For a complete detailing of procedure, please refer to Chapter 15, Article 3, Sections 22.1-306 through 22.1-314 of the Code of Virginia

Virginia\u27s Plan for Dual Enrollment

[First paragraph] There is a plan where Virginia pays Average Daily Membership (ADM) monies to a school system for a student attending a community college - and the community college collects the Full Time Equivalency (FTE) from the State. Principals must be aware of this dual enrollment plan for secondary students with community colleges approved in September of 1988. This plan provides options for students which were not available before. Dual enrollment allows high school students to accumulate credits for graduation while simultaneously earning college credit. The courses to be offered are to be mutually agreed upon by the school division and the community college