63,831 research outputs found
Exact energy spectrum of a two-temperature kinetic Ising model
The exact energy spectrum is developed for a two temperature kinetic Ising
spin chain, and its dual reaction diffusion system with spatially alternating
pair annihilation and creation rates. Symmetries of the system
pseudo-Hamiltonian that enable calculation of the spectrum are also used to
derive explicit state vectors for small system sizes, and to make observations
regarding state vectors in the general case. Physical consequences of the
surprisingly simple form for the eigenvalues are also discussed
Fast pyrolysis of halogenated plastics recovered from waste computers
The disposal of waste computers is an issue that is gaining increasing interest around the world. In this paper, results from the fast pyrolysis in a fluidized bed reactor of three different waste computer monitor casings composed of mainly acrylonitrile-butadiene-styrene (ABS) copolymer and two different waste computer body casings composed of mostly poly(vinyl chloride) (PVC) type polymers are presented. Preliminary characterization of the waste plastics was investigated using coupled thermogravimetric analysis-Fourier transform infrared spectrometry (TGA-FT-IR). The results showed that the plastics decomposed in two stages. For the ABS-containing monitor casings, aromatic and aliphatic material were released in the first and second stages. The PVC-containing computer body casing samples showed a first-stage evolution of HCl and a second stage evolution of aromatic and aliphatic material and further HCl. In addition, each of the five plastics was fast-pyrolyzed in a laboratory-scale fluidized bed reactor at 500 °C. The fluidized bed pyrolysis led to the conversion of most of the plastics to pyrolysis oil, although the two PVC computer body cases produced large quantities of HCl. The pyrolysis oils were characterized by GC-MS and it was found that they were chemically very heterogeneous and contained a wide range of aliphatic, aromatic, halogenated, oxygenated, and nitrogenated compounds
Peering Forward, 10 Years After: International Policy and Consumer Credit Regulation
A key change since the financial crisis of 2008 is the internationalization of interest in consumer finance. International institutions monitor household credit because of its impact on financial stability and market expansion. Macroprudential concerns drove this interest, resulting in a sea change in approaches to consumer credit regulation in many jurisdictions. This article critically analyses the emerging international policy paradigm, contrasting pre-and post-crisis regulatory approaches and highlighting continuing tensions about key policy choices. It then uses two recent sites of contestation, debt adjustment and the regulation of high-cost credit to demostrate the persistence of conflict over the positioning of consumers within an emergent stability focused paradigm of financial consumer protection
Progress in Lunar Laser Ranging Tests of Relativistic Gravity
Analyses of laser ranges to the Moon provide increasingly stringent limits on
any violation of the Equivalence Principle (EP); they also enable several very
accurate tests of relativistic gravity. We report the results of our recent
analysis of Lunar Laser Ranging (LLR) data giving an EP test of \Delta
(M_G/M_I)_{EP} =(-1.0 +/- 1.4) x 10^{-13}. This result yields a Strong
Equivalence Principle (SEP) test of \Delta (M_G/M_I)_{SEP} =(-2.0 +/- 2.0) x
10^{-13}. Also, the corresponding SEP violation parameter \eta is (4.4 +/- 4.5)
x 10^{-4}, where \eta=4\beta-\gamma-3 and both \beta and \gamma are
parametrized post-Newtonian (PPN) parameters. Using the recent Cassini result
for the parameter \gamma, PPN parameter \beta is determined to be \beta-1=(1.2
+/- 1.1) x 10^{-4}. The geodetic precession test, expressed as a relative
deviation from general relativity, is K_{gp}=-0.0019 +/- 0.0064. The search for
a time variation in the gravitational constant results in \dot G/G=(4 +/- 9) x
10^{-13} yr^{-1}, consequently there is no evidence for local (~1AU) scale
expansion of the solar system.Comment: 4 pages, revtex4, minor changes made for publicatio
Stretching single polysaccharide molecules using AFM: A potential method for the investigation of the intermolecular uronate distribution of alginate?
Illustrative examples of the way in which the molecular force-extension behaviour of polysaccharides is governed by the nature of the linkage between their constituent pyranose rings are presented for a series of standard homopolymers. These results agree with previously proposed general hypotheses regarding the possibility of generating force-induced conformational transitions, and with the predictions of a model in which the inter-conversion of pyranose conformers is assumed to be an equilibrium process on the timescale of the molecular stretching. Subsequently, we investigate the potential of the technique in the characterisation of co-polymeric polysaccharides in which the nature of the glycan linkages is different between the two distinct residue types. Specifically, we explore the possibility that the ratio of mannuronic acid (M) to guluronic acid (G) in alginate chains will be reflected in their single molecule stretching behaviour, owing to their contrasting equatorial and axial linkages. Furthermore, as the technique described interrogates the sample one polymer at a time we outline the promise of, and the obstacles to, obtaining a new level of characterisation using this methodology where differences observed in the single molecule stretching curves obtained from single alginate samples reflectsomething of the real intermolecular distribution of the M / G ratio
A discrete time-dependent method for metastable atoms in intense fields
The full-dimensional time-dependent Schrodinger equation for the electronic
dynamics of single-electron systems in intense external fields is solved
directly using a discrete method.
Our approach combines the finite-difference and Lagrange mesh methods. The
method is applied to calculate the quasienergies and ionization probabilities
of atomic and molecular systems in intense static and dynamic electric fields.
The gauge invariance and accuracy of the method is established. Applications to
multiphoton ionization of positronium and hydrogen atoms and molecules are
presented. At very high intensity above saturation threshold, we extend the
method using a scaling technique to estimate the quasienergies of metastable
states of the hydrogen molecular ion. The results are in good agreement with
recent experiments.Comment: 10 pages, 9 figure, 4 table
Multivariate side-band subtraction using probabilistic event weights
A common situation in experimental physics is to have a signal which can not
be separated from a non-interfering background through the use of any cut. In
this paper, we describe a procedure for determining, on an event-by-event
basis, a quality factor (-factor) that a given event originated from the
signal distribution. This procedure generalizes the "side-band" subtraction
method to higher dimensions without requiring the data to be divided into bins.
The -factors can then be used as event weights in subsequent analysis
procedures, allowing one to more directly access the true spectrum of the
signal.Comment: 17 pages, 9 figure
Concurrent Image Processing Executive (CIPE)
The design and implementation of a Concurrent Image Processing Executive (CIPE), which is intended to become the support system software for a prototype high performance science analysis workstation are discussed. The target machine for this software is a JPL/Caltech Mark IIIfp Hypercube hosted by either a MASSCOMP 5600 or a Sun-3, Sun-4 workstation; however, the design will accommodate other concurrent machines of similar architecture, i.e., local memory, multiple-instruction-multiple-data (MIMD) machines. The CIPE system provides both a multimode user interface and an applications programmer interface, and has been designed around four loosely coupled modules; (1) user interface, (2) host-resident executive, (3) hypercube-resident executive, and (4) application functions. The loose coupling between modules allows modification of a particular module without significantly affecting the other modules in the system. In order to enhance hypercube memory utilization and to allow expansion of image processing capabilities, a specialized program management method, incremental loading, was devised. To minimize data transfer between host and hypercube a data management method which distributes, redistributes, and tracks data set information was implemented
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