234,462 research outputs found
The Angular Momenta of Neutron Stars and Black Holes as a Window on Supernovae
It is now clear that a subset of supernovae display evidence for jets and are
observed as gamma-ray bursts. The angular momentum distribution of massive
stellar endpoints provides a rare means of constraining the nature of the
central engine in core-collapse explosions. Unlike supermassive black holes,
the spin of stellar-mass black holes in X-ray binary systems is little affected
by accretion, and accurately reflects the spin set at birth. A modest number of
stellar-mass black hole angular momenta have now been measured using two
independent X-ray spectroscopic techniques. In contrast, rotation-powered
pulsars spin-down over time, via magnetic braking, but a modest number of natal
spin periods have now been estimated. For both canonical and extreme neutron
star parameters, statistical tests strongly suggest that the angular momentum
distributions of black holes and neutron stars are markedly different. Within
the context of prevalent models for core-collapse supernovae, the angular
momentum distributions are consistent with black holes typically being produced
in GRB-like supernovae with jets, and with neutron stars typically being
produced in supernovae with too little angular momentum to produce jets via
magnetohydrodynamic processes. It is possible that neutron stars are imbued
with high spin initially, and rapidly spun-down shortly after the supernova
event, but the available mechanisms may be inconsistent with some observed
pulsar properties.Comment: ApJ Letters, accepte
Improved dispensing targets for ion beam particle generators
Beam impinges on palladium-silver tube, which is target, and heats impinged surface causing local hot spot. Contained gas diffuses through hot spot to meet incoming beam and produce desired particles. When beam is turned off, target spot cools and stops dispensing contained gas
Conflicts between the Massachusetts Supreme Judicial Court and the Legislature: Campaign Finance Reform and Same-Sex Marriage
[Excerpt] This article will examine recent interactions and dialogues between the Supreme Judicial Court of Massachusetts (“SJC” or “Supreme Judicial Court”) and the Massachusetts State Legislature. The interactions between courts and legislatures are often cordial, but sometimes these interactions are also highly conflictual. During the 1980s and 1990s, the relationship between the Massachusetts legislature and the Supreme Court was indeed mainly cooperative. Recently, however, in several high profile cases the Supreme Court has been willing to challenge directly the decisions of the legislature and vice versa. Among other controversies, the Court’s 2002 decision requiring that the state legislature fund the campaign finance reform initiative known in Massachusetts as the Clean Elections law, and the Court’s 2003 decision that same-sex couples could not be denied marriage licenses under the state constitution, have created a great deal of friction between the Supreme Court and the legislature. This article will examine these controversies in some detail in order to gain a better understanding of the different institutional perspectives and different institutional wills that drive the relationship between these two institutions of government. My conclusion is that there needs to be greater communication between the legislative and judicial branches, and that each institution needs to have greater respect for the other body
Low to high temperature energy conversion system
A method for converting heat energy from low temperature heat sources to higher temperature was developed. It consists of a decomposition chamber in which ammonia is decomposed into hydrogen and nitrogen by absorbing heat of decomposition from a low temperature energy source. A recombination reaction then takes place which increases the temperature of a fluid significantly. The system is of use for the efficient operation of compact or low capital investment turbine driven electrical generators, or in other applications, to enable chemical reactions that have a critical lower temperature to be used. The system also recovers heat energy from low temperature heat sources, such as solar collectors or geothermal sources, and converts it to high temperatures
The lunar cart
Expanded experiment-carrying capability, to be used between the Apollo 11 capability and the lunar roving vehicle capability, was defined for the lunar surface crewmen. Methods used on earth to satisfy similar requirements were studied. A two-wheeled cart was built and tested to expected mission requirements and environments. The vehicle was used successfully on Apollo 14
Class numbers of totally real fields and applications to the Weber class number problem
The determination of the class number of totally real fields of large
discriminant is known to be a difficult problem. The Minkowski bound is too
large to be useful, and the root discriminant of the field can be too large to
be treated by Odlyzko's discriminant bounds. We describe a new technique for
determining the class number of such fields, allowing us to attack the class
number problem for a large class of number fields not treatable by previously
known methods. We give an application to Weber's class number problem, which is
the conjecture that all real cyclotomic fields of power of 2 conductor have
class number 1.Comment: Accepted for publication by Acta Arithmetic
The Full Wealth of Conviction and Cognition: Psychology\'s Modernist Critique of Fundamentalism in Postmodern Perspective
The author draws parallels between psychology and religious modernism as exemplified in the writings of such figures as Harry Emerson Fosdick. Miller suggests that psychological research arguing that fundamentalists are \"cognitivcly challenged\" is more reflective of psychology\'s unacknowledged modernist assumptions than descriptive of fundamentalists. A post-modernist recognition of psychology\'s bias should help redirect efforts toward understanding fundamentalists\' pressing desire to preserve a particular orderly culture
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