4,438 research outputs found
Formation Rates of Black Hole Accretion Disk Gamma-Ray Bursts
While many models have been proposed for GRBs, those currently favored are
all based upon the formation of and/or rapid accretion into stellar mass black
holes. We present population synthesis calculations of these models using a
Monte Carlo approach in which the many uncertain parameters intrinsic to such
calculations are varied. We estimate the event rate for each class of model as
well as the propagation distance for those having significant delay between
formation and burst production, i.e., double neutron star (DNS) mergers and
black hole-neutron star (BH/NS) mergers. For reasonable assumptions regarding
the many uncertainties in population synthesis, we calculate a daily event rate
in the universe for i) merging neutron stars: ~100/day; ii) neutron-star black
hole mergers: ~450/day; iii) collapsars: ~10,000/day; iv) helium star black
hole mergers: ~1000/day; and v) white dwarf black hole mergers: ~20/day. The
range of uncertainty in these numbers however, is very large, typically two to
three orders of magnitude. These rates must additionally be multiplied by any
relevant beaming factor and sampling fraction (if the entire universal set of
models is not being observed). Depending upon the mass of the host galaxy, half
of the DNS and BH/NS mergers will happen within 60kpc (for a Milky-Way massed
galaxy) to 5Mpc (for a galaxy with negligible mass) from the galactic center.
Because of the delay time, neutron star and black hole mergers will happen at a
redshift 0.5 to 0.8 times that of the other classes of models. Information is
still lacking regarding the hosts of short hard bursts, but we suggest that
they are due to DNS and BH/NS mergers and thus will ultimately be determined to
lie outside of galaxies and at a closer mean distance than long complex bursts
(which we attribute to collapsars).Comment: 57 pages total, 23 figures, submitted by Ap
Maine Corporation Law & Practice
The scarcity of case law in Maine on corporate law issues of the day is a fact of life for corporate law practitioners in this State. While courts in more populous states fill library shelves with an ever-growing mix of corporate law decisions, we in Maine often can only wonder which way our own courts would turn if presented with those same issues. Faced with a limited amount of local case law, corporate lawyers here might rarely venture beyond well-hewn traditions were it not for two-and now three-fortunate developments. First and foremost is the Maine Business Corporation Act. The Act is the product of immense effort on the part of a committee of Maine business lawyers who in 1971 presented the Legislature with a statutory framework so pragmatic and flexible as to have survived the last two tumultuous decades with surprisingly few signs of age. The second fortunate development is a set of post-1971 decisions from the Maine Supreme Judicial Court, sitting as the Law Court, that have been broadly supportive of the corporate form and of directors\u27 managerial discretion. The third fortunate development has been the recent appearance of James Zimpritch\u27s treatise Maine Corporation Law & Practice, a large and patient work that helps the reader place the Maine Business Corporation Act and Maine Law Court decisions (both old and new) in a broader analytical framework. In Maine Corporation Law & Practice James Zimpritch has not been content merely to summarize the Act and cross-reference the case law. Every chapter attempts to place the relevant statutory provisions in some useful context-in context with other provisions of the Act, in context with prior Maine corporation statutes, in context with the Model Business Corporation Act or with statutory provisions from certain other states, in context with decisions of courts in Maine and selected cases from other jurisdictions, and so forth. In the words of the author, A purpose of this book has been to draw together the authorities that exist, in an effort to explain the corporate law of Maine. \u2
Maine Corporation Law & Practice
The scarcity of case law in Maine on corporate law issues of the day is a fact of life for corporate law practitioners in this State. While courts in more populous states fill library shelves with an ever-growing mix of corporate law decisions, we in Maine often can only wonder which way our own courts would turn if presented with those same issues. Faced with a limited amount of local case law, corporate lawyers here might rarely venture beyond well-hewn traditions were it not for two-and now three-fortunate developments. First and foremost is the Maine Business Corporation Act. The Act is the product of immense effort on the part of a committee of Maine business lawyers who in 1971 presented the Legislature with a statutory framework so pragmatic and flexible as to have survived the last two tumultuous decades with surprisingly few signs of age. The second fortunate development is a set of post-1971 decisions from the Maine Supreme Judicial Court, sitting as the Law Court, that have been broadly supportive of the corporate form and of directors\u27 managerial discretion. The third fortunate development has been the recent appearance of James Zimpritch\u27s treatise Maine Corporation Law & Practice, a large and patient work that helps the reader place the Maine Business Corporation Act and Maine Law Court decisions (both old and new) in a broader analytical framework. In Maine Corporation Law & Practice James Zimpritch has not been content merely to summarize the Act and cross-reference the case law. Every chapter attempts to place the relevant statutory provisions in some useful context-in context with other provisions of the Act, in context with prior Maine corporation statutes, in context with the Model Business Corporation Act or with statutory provisions from certain other states, in context with decisions of courts in Maine and selected cases from other jurisdictions, and so forth. In the words of the author, A purpose of this book has been to draw together the authorities that exist, in an effort to explain the corporate law of Maine. \u2
Late-Time Convection in the Collapse of a 23 Solar Mass Star
The results of a 3-dimensional SNSPH simulation of the core collapse of a 23
solar mass star are presented. This simulation did not launch an explosion
until over 600ms after collapse, allowing an ideal opportunity to study the
evolution and structure of the convection below the accretion shock to late
times. This late-time convection allows us to study several of the recent
claims in the literature about the role of convection: is it dominated by an
l=1 mode driven by vortical-acoustic (or other) instability, does it produce
strong neutron star kicks, and, finally, is it the key to a new explosion
mechanism? The convective region buffets the neutron star, imparting a 150-200
km/s kick. Because the l=1 mode does not dominate the convection, the neutron
star does not achieve large (>450 km/s) velocities. Finally, the neutron star
in this simulation moves, but does not develop strong oscillations, the energy
source for a recently proposed supernova engine. We discuss the implications
these results have on supernovae, hypernovae (and gamma-ray bursts), and
stellar-massed black holes.Comment: 31 pages (including 13 figures), submitted to Ap
The intermediate state in Paul
The intermediate state in PaulThe point of view taken in this paper is that the apostle Paul envisions, between death and the resurrection of the body at the Parousia, an interim period during which the disembodied soul is in the immediate presence of Christ, though in a state of 'nakedness'. The background of Paul's view lies neither in contemporary Hellenistic religious-philosophical speculations nor in 'late-Judaism'. Two crucial 'forces' in particular moulded his perspective, viz the teachings of Jesus and His own raptureto 'Paradise'
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