21,973 research outputs found
Numerical Method for Shock Front Hugoniot States
We describe a Continuous Hugoniot Method for the efficient simulation of
shock wave fronts. This approach achieves significantly improved efficiency
when the generation of a tightly spaced collection of individual steady-state
shock front states is desired, and allows for the study of shocks as a function
of a continuous shock strength parameter, . This is, to our knowledge, the
first attempt to map the Hugoniot continuously. We apply the method to shock
waves in Lennard-Jonesium along the direction. We obtain very good
agreement with prior simulations, as well as our own benchmark comparison runs.Comment: 4 pages, 3 figures, from Shock Compression of Condensed Matter 200
An Introduction to Slice-Based Cohesion and Coupling Metrics
This report provides an overview of slice-based software metrics. It brings together information about the development of the metrics from Weiser’s original idea that program slices may be used in the measurement of program complexity, with alternative slice-based measures proposed by other researchers. In particular, it details two aspects of slice-based metric calculation not covered elsewhere in the literature: output variables and worked examples of the calculations. First, output variables are explained, their use explored and standard reference terms and usage proposed. Calculating slice-based metrics requires a clear understanding of ‘output variables’ because they form the basis for extracting the program slices on which the calculations depend. This report includes a survey of the variation in the definition of output variables used by different research groups and suggests standard terms of reference for these variables. Our study identifies four elements which are combined in the definition of output variables. These are the function return value, modified global variables, modified reference parameters and variables printed or otherwise output by the module. Second, slice-based metric calculations are explained with the aid of worked examples, to assist newcomers to the field. Step-by-step calculations of slice-based cohesion and coupling metrics based on the vertices output by the static analysis tool CodeSurfer (R) are presented and compared with line-based calculations
The Effect of the Internet on the Advertising Industry in a Consumer Culture
A revolution is under way, possibly of the same magnitude as the 19th Century industrial revolution. The information age is upon us at an unparalleled rate of growth. The Internet spearheads the drive forward towards a world where knowledge that shapes our lives is truly common, affecting every culture on the planet. Commercial advertising is the science of disseminating information in a meaningful way and it is therefore relevant to wonder how this new-world order will affect both advertising and the underlying cultures. When will it happen? Who will it affect? What form will it take? How will it affect our national cultures and what benefits or disbenefits will follow? What will happen to the advertising industry? Where will the opportunities be? This study has aimed to answer these questions and to apply them to our underlying consumer culture, targeting the impact of the Internet on advertising and its’ direction
Research and development program on magnetic electrical conductor, electrical insulation, and bore seal materials - Electrical conductor and electrical insulation materials topical report
Electrical, mechanical, and thermo-physical properties of conductor and insulation materials for application to advanced space electric power system
The bird: A pressure-confined explosion in the interstellar medium
The non-thermal radio continuum source G5.3-1.0, mapped at 20 cm with the Very Large Array (VLA) by Becker and Helfand, has an unusual bird-like shape. In order to determine possible interaction of this source with adjacent cold gas, we have mapped this region in the J=1-0 line of CO using the AT and T Bell Laboratories 7m antenna and the FCRAO 14m antenna. The map shown contains 1859 spectra sampled on a 1.5 arcminute grid; each spectrum has an rms noise of 0.2 K in 1 MHz channels. There are several molecular clouds at different velocities along the line of sight. The outer regions of a previously unknown Giant Molecular Cloud (GMC) at l=4.7 deg., b=-0.85 deg., v=200 km s(-1) appears to be interacting with G5.3-10: the molecular cloud has a bird-shaped hole at the position of the continuum source, except that the brightest continuum point (the bird's head) appears to be embedded in the cloud. The velocity of this GMC indicates it is within 2 kpc of the galactic center. The morphology suggests that a supernova or other explosive event occurred near the outside of the GMC, in a region where (n) is approximately 300 cm(-3), and expanded into a region of lower density and pressure. The pressures, densities, and velocity gradients of molecular clouds near the galactic center are on average higher than those of clouds near the Sun. We therefore expect that Type II supernovae near the galactic center would be distorted by their interactions with their parent molecular clouds
Scotin, a novel p53-inducible proapoptotic protein located in the ER and the nuclear membrane
p53 is a transcription factor that induces growth arrest or apoptosis in response to cellular stress. To identify new p53-inducible proapoptotic genes, we compared, by differential display, the expression of genes in spleen or thymus of normal and p53 nullizygote mice after γ-irradiation of whole animals. We report the identification and characterization of human and mouse Scotin homologues, a novel gene directly transactivated by p53. The Scotin protein is localized to the ER and the nuclear membrane. Scotin can induce apoptosis in a caspase-dependent manner. Inhibition of endogenous Scotin expression increases resistance to p53-dependent apoptosis induced by DNA damage, suggesting that Scotin plays a role in p53-dependent apoptosis. The discovery of Scotin brings to light a role of the ER in p53-dependent apoptosis
Monoids, Embedding Functors and Quantum Groups
We show that the left regular representation \pi_l of a discrete quantum
group (A,\Delta) has the absorbing property and forms a monoid
(\pi_l,\tilde{m},\tilde{\eta}) in the representation category Rep(A,\Delta).
Next we show that an absorbing monoid in an abstract tensor *-category C gives
rise to an embedding functor E:C->Vect_C, and we identify conditions on the
monoid, satisfied by (\pi_l,\tilde{m},\tilde{\eta}), implying that E is
*-preserving. As is well-known, from an embedding functor E: C->\mathrm{Hilb}
the generalized Tannaka theorem produces a discrete quantum group (A,\Delta)
such that C is equivalent to Rep_f(A,\Delta). Thus, for a C^*-tensor category C
with conjugates and irreducible unit the following are equivalent: (1) C is
equivalent to the representation category of a discrete quantum group
(A,\Delta), (2) C admits an absorbing monoid, (3) there exists a *-preserving
embedding functor E: C->\mathrm{Hilb}.Comment: Final version, to appear in Int. Journ. Math. (Added some references
and Subsection 1.2.) Latex2e, 21 page
The susceptibility of roots to infection by an arbuscular mycorrhizal fungus in relation to age and phosphorus supply
An apparatus in which plant roots may be challenged uniformly with inoculum of arbuscular mycorrhizal fungi is described. Seedlings of leek (Allium porrum L.) or clover (Trifolium repens L.) were first grown non-symbiotically in the apparatus for 21 d at three rates of phosphorus (P) addition to soil (1 50 (PI), 450 (P3) and 750 (P5) mg P kg-1 soil). The positions of individual root tips were recorded, and the root systems then challenged with inoculum of Glomus mosseae (Nicol & Gerd.) Gerdemann & Trappe. Roots were excised 14 d later, and the probability of occurrence of internal infection in successive 3 mm (clover) or 5 mm (leek) sections of root was estimated in first-order laterals (clover) or main axes (leek) from the proportion of sections at each location of replicate roots that bore internal fungal structures. Only in the region of a root proximal to the position of the root tips at inoculation could data be used to investigate change of probability of infection with cell age. Here, there were sharp declines in probability of infection with proximal distance, in both hosts and in all P treatments. The decline of probability was greater in clover: when expressed in terms of cell age at the time of challenge, there was no infection at Pl in cells > 10 d old in leek and none in cells > 7 d old in clover. Models of the form log(e) [p(i)/(1-p(i))] = alpha + beta x distance, where p(i) is the estimated probability of infection and alpha and beta are constants, were fitted to these data. The odds on infection are [p(i)/(1-p(i))]. For leek, 8 was unaltered by P addition (P3 and P5 curves were parallel to P1) but from alpha it could be calculated that on average the odds on successful infection at any particular distance were reduced by 3 7 % and 70 % by P3 and P5 rates of P addition respectively. In clover the curves for the three P treatments were not parallel. Addition of P appeared to reduce the odds on infection of clover much more than those of leek. We conclude that the simplest explanation for the patterns of infection in leek is that P addition increased the time taken for soil inoculum of G. mosseae to infect roots: the mechanism in clover might be more complex
Statistical Geometry in Quantum Mechanics
A statistical model M is a family of probability distributions, characterised
by a set of continuous parameters known as the parameter space. This possesses
natural geometrical properties induced by the embedding of the family of
probability distributions into the Hilbert space H. By consideration of the
square-root density function we can regard M as a submanifold of the unit
sphere in H. Therefore, H embodies the `state space' of the probability
distributions, and the geometry of M can be described in terms of the embedding
of in H. The geometry in question is characterised by a natural Riemannian
metric (the Fisher-Rao metric), thus allowing us to formulate the principles of
classical statistical inference in a natural geometric setting. In particular,
we focus attention on the variance lower bounds for statistical estimation, and
establish generalisations of the classical Cramer-Rao and Bhattacharyya
inequalities. The statistical model M is then specialised to the case of a
submanifold of the state space of a quantum mechanical system. This is pursued
by introducing a compatible complex structure on the underlying real Hilbert
space, which allows the operations of ordinary quantum mechanics to be
reinterpreted in the language of real Hilbert space geometry. The application
of generalised variance bounds in the case of quantum statistical estimation
leads to a set of higher order corrections to the Heisenberg uncertainty
relations for canonically conjugate observables.Comment: 32 pages, LaTex file, Extended version to include quantum measurement
theor
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