13,605 research outputs found
CO on Ru(001): Formation and dissolution of islands of CO at low coverages
The present paper deals with the benefits and difficulties of using ion scattering spectroscopy as a spectrometric technique
Principles of Antifragile Software
The goal of this paper is to study and define the concept of "antifragile
software". For this, I start from Taleb's statement that antifragile systems
love errors, and discuss whether traditional software dependability fits into
this class. The answer is somewhat negative, although adaptive fault tolerance
is antifragile: the system learns something when an error happens, and always
imrpoves. Automatic runtime bug fixing is changing the code in response to
errors, fault injection in production means injecting errors in business
critical software. I claim that both correspond to antifragility. Finally, I
hypothesize that antifragile development processes are better at producing
antifragile software systems.Comment: see https://refuses.github.io
Direct measurement of xenon flashtube opacity
Opacity measurement of xenon flash tube - optical mase
Strange two-baryon interactions using chiral effective field theory
We have constructed the leading order strangeness S=-1,-2 baryon-baryon
potential in a chiral effective field theory approach. The chiral potential
consists of one-pseudoscalar-meson exchanges and non-derivative four-baryon
contact terms. The potential, derived using SU(3)_f symmetry constraints,
contains six independent low-energy coefficients. We have solved a regularized
Lippmann-Schwinger equation and achieved a good description of the available
scattering data. Furthermore a correctly bound hypertriton has been obtained.Comment: 3 pages, 2 PostScript figures, talk to appear in the proceedings of
the "20th European Conference on Few-Body Problems in Physics (EFB20), Pisa,
Italy, 10-14 September 2007
Using Perturbative Least Action to Recover Cosmological Initial Conditions
We introduce a new method for generating initial conditions consistent with
highly nonlinear observations of density and velocity fields. Using a variant
of the Least Action method, called Perturbative Least Action (PLA), we show
that it is possible to generate several different sets of initial conditions,
each of which will satisfy a set of highly nonlinear observational constraints
at the present day. We then discuss a code written to test and apply this
method and present the results of several simulations.Comment: 24 pages, 6 postscript figures. Accepted for publication in
Astrophysical Journa
Oxidation of carbon monoxide over Ag (111) by preadsorbed active oxygen studied by XPS and UPS
N/
NVV auger spectra from W(100)
The NVV Auger spectrum from a clean W(100) surface has been measured in the second derivative, d^2N (E)/dE^2, mode to enhance fine structure. This measurement is compared with spectra generated from both the self‐convolution of the tungsten valence‐band bulk density of states (obtained from a relativistic APW energy band calculation) and a "restricted convolution" in which only transitions involving electrons from the same valence energy are allowed. The restricted convolution for a model of the Auger process in which both N_6VV and N_7VV transitions contribute offers the best match of theory and experiment. No distinct evidence of Auger emission involving the surface resonance present on W(100) is observed. Effects of H_2 and O_2 adsorption on the Auger spectrum of the W(100) surface are reported
Cosmological Density Perturbations with a Scale-Dependent Newton's G
We explore possible cosmological consequences of a running Newton's constant
, as suggested by the non-trivial ultraviolet fixed point
scenario in the quantum field-theoretic treatment of Einstein gravity with a
cosmological constant term. In particular we focus here on what possible
effects the scale-dependent coupling might have on large scale cosmological
density perturbations. Starting from a set of manifestly covariant effective
field equations derived earlier, we systematically develop the linear theory of
density perturbations for a non-relativistic, pressure-less fluid. The result
is a modified equation for the matter density contrast, which can be solved and
thus provides an estimate for the growth index parameter in the
presence of a running . We complete our analysis by comparing the fully
relativistic treatment with the corresponding results for the non-relativistic
(Newtonian) case, the latter also with a weakly scale dependent .Comment: 54 pages, 4 figure
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