567 research outputs found
The Essentials of NY Mental Health Law: A Straightforward Guide for Clinicians of All Disciplines
Table of Contents onlyhttps://digitalcommons.nyls.edu/fac_books/1122/thumbnail.jp
Ariel - Volume 6 Number 2
Editors
Mark Dembert
J.D. Kanofsky
Frank Chervenak
John Lammie
Curt Cummings
Entertainment
Robert Breckenridge
Joe Conti
Gary Kaskey
Photographer
Larry Glazerman
Overseas Editor
Mike Sinason
Humorist
Jim McCann
Staff
Ken Jaffe
Bob Skarloff
Halley Faust
Jim Burk
Time varying in N=8 extended Supergravity
There has been some evidence that the fine structure "constant" may
vary with time. We point out that this variation can be described by a scalar
field in some supergravity theory in our toy model, for instance, the N=8
extended supergravity in four dimensions which can be accommodated in M-theory.Comment: 5 pages,1 figures. Accepted for publication in JHE
Power spectrum and correlation function errors: Poisson vs. Gaussian shot noise
Poisson distributed shot noise is normally considered in the Gaussian limit
in cosmology. However, if the shot noise is large enough and the correlation
function/power spectrum conspires, the Gaussian approximation mis-estimates the
errors and their covariance significantly. The power spectrum, even for
initially Gaussian densities,acquires cross correlations which can be large,
while the change in the correlation function error matrix is diagonal except at
zero separation. Two and three dimensional power law correlation function and
power spectrum examples are given. These corrections appear to have a large
effect when applied to galaxy clusters, e.g. for SZ selected galaxy clusters in
2 dimensions. This can increase the error estimates for cosmological parameter
estimation and consequently affect survey strategies, as the corrections are
minimized for surveys which are deep and narrow rather than wide and shallow.
In addition, a rewriting of the error matrix for the power spectrum/correlation
function is given which eliminates most of the Bessel function dependence (in
two dimensions) and all of it (in three dimensions), which makes the
calculation of the error matrix more tractable. This applies even when the shot
noise is in the (usual) Gaussian limit.Comment: 22 pages, 4 figures, 3 equations corrected/figures updated, results
unchange
Radiation recoil from highly distorted black holes
We present results from numerical evolutions of single black holes distorted
by axisymmetric, but equatorially asymmetric, gravitational (Brill) waves. Net
radiated energies, apparent horizon embeddings, and recoil velocities are shown
for a range of Brill wave parameters, including both even and odd parity
distortions of Schwarzschild black holes. We find that a wave packet initially
concentrated on the black hole throat, a likely model also for highly
asymmetric stellar collapse and late stage binary mergers, can generate a
maximum recoil velocity of about 150 (23) km/sec for even (odd) parity
perturbations, significantly less than that required to eject black holes from
galactic cores.Comment: 15 pages, 8 figure
Black hole boundaries
Classical black holes and event horizons are highly non-local objects,
defined in relation to the causal past of future null infinity. Alternative,
quasilocal characterizations of black holes are often used in mathematical,
quantum, and numerical relativity. These include apparent, killing, trapping,
isolated, dynamical, and slowly evolving horizons. All of these are closely
associated with two-surfaces of zero outward null expansion. This paper reviews
the traditional definition of black holes and provides an overview of some of
the more recent work on alternative horizons.Comment: 27 pages, 8 figures, invited Einstein Centennial Review Article for
CJP, final version to appear in journal - glossary of terms added, typos
correcte
Pragmatic Software Innovation
Part 2: Creating Value through Software DevelopmentInternational audienceWe understand software innovation as concerned with introducing innovation into the development of software intensive systems, i.e. systems in which software development and/or integration are dominant considerations. Innovation is key in almost any strategy for competitiveness in existing markets, for creating new markets, or for curbing rising public expenses, and software intensive systems are core elements in most such strategies. Software innovation therefore is vital for about every sector of the economy. Changes in software technologies over the last decades have opened up for experimentation, learning, and flexibility in ongoing software projects, but how can this change be used to facilitate software innovation? How can a team systematically identify and pursue opportunities to create added value in ongoing projects? In this paper, we describe Deweyan pragmatism as the philosophical foundation for Essence – a software innovation methodology – where unknown options and needs emerge as part of the development process itself. The foundation is illustrated via a simple example
Instrumentation progress at the Giant Magellan Telescope project
Instrument development for the 24m Giant Magellan Telescope (GMT) is described: current activities, progress, status, and schedule. One instrument team has completed its preliminary design and is currently beginning its final design (GCLEF, an optical 350-950 nm, high-resolution and precision radial velocity echelle spectrograph). A second instrument team is in its conceptual design phase (GMACS, an optical 350-950 nm, medium resolution, 6-10 arcmin field, multiobject spectrograph). A third instrument team is midway through its preliminary design phase (GMTIFS, a near-IR YJHK diffraction-limited imager/integral-field-spectrograph), focused on risk reduction prototyping and design optimization. A fourth instrument team is currently fabricating the 5 silicon immersion gratings needed to begin its preliminary design phase (GMTNIRS, a simultaneous JHKLM high-resolution, AO-fed, echelle spectrograph). And, another instrument team is focusing on technical development and prototyping (MANIFEST, a facility robotic, multifiber-feed, with a 20 arcmin field of view). In addition, a medium-field (6 arcmin, 0.06 arcsec/pix) optical imager will support telescope and AO commissioning activities, and will excel at narrow-band imaging. In the spirit of advancing synergies with other groups, the challenges of running an ELT instrument program and opportunities for cross-ELT collaborations are discussed
Improving the Performance of the SYND Stream Cipher
International audience. In 2007, Gaborit et al. proposed the stream cipher SYND as an improvement of the pseudo random number generator due to Fischer and Stern. This work shows how to improve considerably the e ciency the SYND cipher without using the so-called regular encoding and without compromising the security of the modi ed SYND stream cipher. Our proposal, called XSYND, uses a generic state transformation which is reducible to the Regular Syndrome Decoding problem (RSD), but has better computational characteristics than the regular encoding. A rst implementation shows that XSYND runs much faster than SYND for a comparative security level (being more than three times faster for a security level of 128 bits, and more than 6 times faster for 400-bit security), though it is still only half as fast as AES in counter mode. Parallel computation may yet improve the speed of our proposal, and we leave it as future research to improve the e ciency of our implementation
A New Relativistic High Temperature Bose-Einstein Condensation
We discuss the properties of an ideal relativistic gas of events possessing
Bose-Einstein statistics. We find that the mass spectrum of such a system is
bounded by where is the usual chemical
potential, is an intrinsic dimensional scale parameter for the motion of an
event in space-time, and is an additional mass potential of the
ensemble. For the system including both particles and antiparticles, with
nonzero chemical potential the mass spectrum is shown to be bounded by
and a special type of high-temperature
Bose-Einstein condensation can occur. We study this Bose-Einstein condensation,
and show that it corresponds to a phase transition from the sector of
continuous relativistic mass distributions to a sector in which the boson mass
distribution becomes sharp at a definite mass This phenomenon
provides a mechanism for the mass distribution of the particles to be sharp at
some definite value.Comment: Latex, 22 page
- …