429 research outputs found
On the oxide formation on stainless steels AISI 304 and incoloy 800H investigated with XPS
The influence of cold work on the initially formed oxide layer on the stainless steels AISI 304 and Incology 800H has been studied by XPS. Oxidations were performed at pressures of 10-6-10-4 Pa and temperatures of 300–800 K. All samples showed a similar oxidation behaviour. The oxidation rates of iron and chromium are of the same order of magnitude at temperatures below 650 K. Subsequent oxidation results in an iron oxide on top of a chromium oxide layer. At temperatures above 650 K the metal surface becomes enriched in chromium, which is preferentially oxidized at these temperatures and pressures. Even prolonged oxidation does not result in an iron-rich oxide surface. Nickel has never been found in its oxidized form. The binding energy of oxygen, in the various oxide layers, is independent of the extent of oxidation and is 530.6 eV
Nonlocal effects in the shot noise of diffusive superconductor - normal-metal systems
A cross-shaped diffusive system with two superconducting and two normal
electrodes is considered. A voltage is applied between the normal
leads. Even in the absence of average current through the superconducting
electrodes their presence increases the shot noise at the normal electrodes and
doubles it in the case of a strong coupling to the superconductors. The
nonequilibrium noise at the superconducting electrodes remains finite even in
the case of a vanishingly small transport current due to the absence of energy
transfer into the superconductors. This noise is suppressed by
electron-electron scattering at sufficiently high voltages.Comment: 4 pages, RevTeX, 2 eps figure
The Recurrent Nature of Central Starbursts
New hydrodynamic models with feedback show that feedback driven turbulence
and subsequent relaxation can drive recurrent starbursts, though most of these
bursts fizzle due to premature, asymmetric ignition. Strong bursts are
terminated when the turbulence inflates the multiphase central disk. The period
between bursts is about twice a free-fall time onto the central disk. Transient
spirals and bars are common through the burst cycle.Comment: 7 pages + 3 figs. Conf. paper for "Starbursts: from 30 Doradus to
Lyman Break Galaxies," held at Inst. of Astronomy, Cambridge Univ., Sept.
6-10, 2004. Kluwer Academic Publishers, eds. R. de Grijs and R. M. Gonzalez
Delgado + additional materia
Can free-electron lasers answer critical questions in ultraviolet photobiology?
No abstract prepared
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Soft x-ray circular dichroism and scattering using a modulated elliptically polarizing wiggler and double synchronous detection
We have constructed an experimental station (beamline) at the National Synchrotron Light Source to measure circular dichroism (CD) using soft x-rays (250 {le} hv {le} 900 eV) from a time modulated elliptically polarizing wiggler. The polarization of the soft x-ray beam switches periodically between two opposite polarizations, hence permitting the use of phase-sensitive (lock-in) detection. While the wiggler can be modulated at frequencies up to 100 Hz, switching transients limit the actual practical frequency to {approx}25 Hz. With analog detection, switching transients are blocked by a chopper synchronized to the frequency and phase of the wiggler. The CD is obtained from the ratio of the signal recovered at the frequency of polarization modulation, f, to the average beam intensity, which is recovered by synchronous detection at frequency 2f
Conservation practice could benefit from routine testing and publication of management outcomes
Effective conservation requires a step change in the way practitioners can contribute to science and
can have access to research outputs. The journal Conservation Evidence was established in 2004 to
help practitioners surmount several obstacles they face when attempting to document the effects of
their conservation actions scientifically. It is easily and freely accessible online. It is free to publish in
and it enables global communication of the effects of practical trials and experiments, which are
virtually impossible to get published in most scientific journals. The driving force behind
Conservation Evidence is the need to generate and share scientific information about the effects of
interventions
Beyond convenience: practical considerations with using routine health data for evaluations
As digital routine health information systems (RHIS) become more prevalent, there is a growing interest in using them for evaluations. Rakha et al. used data from an integrated management of childhood illness (IMCI) database to evaluate under-5 mortality and the timing of IMCI implementation in 213 districts in Egypt. Bennett et al. used data from Zambia’s RHIS to evaluate an insecticide-treated net program and confirmed outpatient malaria incidence. Lalla-Edward et al. used data collected from nine roadside wellness centers in South Africa to evaluate the services accessed by long-distance truck drivers and the drivers’ sociodemographic characteristics. Brennan et al. used data from the National Health Service (NHS) in Leicester to assess hospital cost efficiency
Inozemtsev's hyperbolic spin model and its related spin chain
In this paper we study Inozemtsev's su(m) quantum spin model with hyperbolic
interactions and the associated spin chain of Haldane-Shastry type introduced
by Frahm and Inozemtsev. We compute the spectrum of Inozemtsev's model, and use
this result and the freezing trick to derive a simple analytic expression for
the partition function of the Frahm-Inozemtsev chain. We show that the energy
levels of the latter chain can be written in terms of the usual motifs for the
Haldane-Shastry chain, although with a different dispersion relation. The
formula for the partition function is used to analyze the behavior of the level
density and the distribution of spacings between consecutive unfolded levels.
We discuss the relevance of our results in connection with two well-known
conjectures in quantum chaos.Comment: 22 pages, RevTeX, 7 figure
On the solutions of multicomponent generalizations of the Lam{\'e} equation
We describe a class of the singular solutions to the multicomponent analogs
of the Lam{\'e} equation, arising as equations of motion of the elliptic
Calogero--Moser systems of particles carrying spin 1/2. At special value of the
coupling constant we propose the ansatz which allows one to get meromorphic
solutions with two arbitrary parameters. They are quantized upon the
requirement of the regularity of the wave function on the hyperplanes at which
particles meet and imposing periodic boundary conditions. We find also the
extra integrals of motion for three-particle systems which commute with the
Hamiltonian for arbitrary values of the coupling constant.Comment: 8 pages, 1 table, no figures, revtex
Thermal radiation processes
We discuss the different physical processes that are important to understand
the thermal X-ray emission and absorption spectra of the diffuse gas in
clusters of galaxies and the warm-hot intergalactic medium. The ionisation
balance, line and continuum emission and absorption properties are reviewed and
several practical examples are given that illustrate the most important
diagnostic features in the X-ray spectra.Comment: 37 pages, 16 figures, accepted for publication in Space Science
Reviews, special issue "Clusters of galaxies: beyond the thermal view",
Editor J.S. Kaastra, Chapter 9; work done by an international team at the
International Space Science Institute (ISSI), Bern, organised by J.S.
Kaastra, A.M. Bykov, S. Schindler & J.A.M. Bleeke
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