4,635 research outputs found
Television: Peer-To-Peer’s Next Challenger
The entertainment industry has obsessed over the threat of peer-to-peer file sharing since the introduction of Napster in 1999. The sharing of television content may present a compelling case for fair use under the long-standing Betamax decision. Some argue that television sharing is fundamentally different than the distribution of music or movies since television is often distributed for free over public airwaves. However, a determination of fair use is unlikely because of the fundamental differences between recording a program and downloading it, recent regulation to suppress unauthorized content distribution and shifts in the television market brought on by new technology
The Effects of Inhomogeneities on Evaluating the Deceleration Parameter q
Analytic expressions for distance-redshift relations which have been
corrected for the effects of some inhomogeneities in the
Friedmann-Robertson-Walker (FRW) mass density are used to illustrate the
significance of inhomogeneities on a determination of made by using Type
Ia supernovae. The value of inferred from a given set of observations
depends on the fractional amount of matter in inhomogeneities and is up to 50
percent larger than that obtained by using the standard Mattig - result
for pure dust FRW models.Comment: 16 pages, 7 figures in separate uuencoded fil
Supernova Resonance-Scattering Profiles in the Presence of External Illumination
We discuss a simple model for the formation of a supernova spectral line by
resonance scattering in the presence of external illumination of the
line-forming region by light from circumstellar interaction (toplighting). The
simple model provides a clear understanding of the most conspicuous toplighting
effect: a rescaling or, as we prefer, a ``muting'' of the line profile relative
to the continuum. This effect would be present in more realistic models, but
would be harder to isolate. An analytic expression for a muting factor for a
P-Cygni line is derived that depends on the ratio E of the toplighting specific
intensity to the specific intensity from the supernova photosphere. If E<1, the
line profile is reduced in scale or ``muted''. If E=1, the line profile
vanishes altogether. If E>1, the line profile flips vertically: then having an
absorption component near the observer-frame line center wavelength and a
blueshifted emission component.Comment: accepted for publication in PAS
On the Spectrum and Nature of the Peculiar Type Ia Supernova 1991T
A parameterized supernova synthetic-spectrum code is used to study line
identifications in the photospheric-phase spectra of the peculiar Type Ia SN
1991T, and to extract some constraints on the composition structure of the
ejected matter. The inferred composition structure is not like that of any
hydrodynamical model for Type Ia supernovae. Evidence that SN 1991T was
overluminous for an SN Ia is presented, and it is suggested that this peculiar
event probably was a substantially super-Chandrasekhar explosion that resulted
from the merger of two white dwarfs.Comment: 1 text, 7 figures, submitted to MNRA
Managing the Regulatory State: The Experience of the Bush Administration
This Article traces the history of Presidential management of the regulatory state up to the administration of President George W. Bush. It focuses on the latter\u27s implementation of smarter regulation, an approach to regulation based on unfunded mandates on the private sector implemented through the Office of Management and Budget, an organization within the Executive Office of the President. It finds cost-benefit analysis an essential, yet often neglected, tool for implementing efficient and effective regulations. It concludes the policies promoted under President Bush\u27s OMB have effectively cut costs by streamlining the rule-making process and discouraging adopting new federal rules, but cautions there is still a sea of overlapping regulations and conflict over turf among agencies causing the administrative state to steadily rise in cost
SN 2005hj: Evidence for Two Classes of Normal-Bright SNe Ia and Implications for Cosmology
HET Optical spectra covering the evolution from about 6 days before to about
5 weeks after maximum light and the ROTSE-IIIb unfiltered light curve of the
"Branch-normal" Type Ia Supernova SN 2005hj are presented. The host galaxy
shows HII region lines at redshift of z=0.0574, which puts the peak unfiltered
absolute magnitude at a somewhat over-luminous -19.6. The spectra show weak and
narrow SiII lines, and for a period of at least 10 days beginning around
maximum light these profiles do not change in width or depth and they indicate
a constant expansion velocity of ~10,600 km/s. We analyzed the observations
based on detailed radiation dynamical models in the literature. Whereas delayed
detonation and deflagration models have been used to explain the majority of
SNe Ia, they do not predict a long velocity plateau in the SiII minimum with an
unvarying line profile. Pulsating delayed detonations and merger scenarios form
shell-like density structures with properties mostly related to the mass of the
shell, M_shell, and we discuss how these models may explain the observed SiII
line evolution; however, these models are based on spherical calculations and
other possibilities may exist. SN 2005hj is consistent with respect to the
onset, duration, and velocity of the plateau, the peak luminosity and, within
the uncertainties, with the intrinsic colors for models with M_shell=0.2 M_sun.
Our analysis suggests a distinct class of events hidden within the
Branch-normal SNe Ia. If the predicted relations between observables are
confirmed, they may provide a way to separate these two groups. We discuss the
implications of two distinct progenitor classes on cosmological studies
employing SNe Ia, including possible differences in the peak luminosity to
light curve width relation.Comment: ApJ accepted, 31 page
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