187 research outputs found
Increasing Automation in the Backporting of Linux Drivers Using Coccinelle
International audienceSoftware is continually evolving, to fix bugs and add new features. Industry users, however, often value stability, and thus may not be able to update their code base to the latest versions. This raises the need to selectively backport new features to older software versions. Traditionally, backporting has been done by cluttering the backported code with preprocessor directives, to replace behaviors that are unsupported in an earlier version by appropriate workarounds. This approach however involves writing a lot of error-prone backporting code, and results in implementations that are hard to read and maintain. We consider this issue in the context of the Linux kernel, for which older versions are in wide use. We present a new backporting strategy that relies on the use of a backporting compatability library and on code that is automatically generated using the program transformation tool Coccinelle. This approach reduces the amount of code that must be manually written, and thus can help the Linux kernel backporting effort scale while maintaining the dependability of the backporting process
Measurement of the reaction \gamma p \TO K^ + \Lambda(1520) at photon energies up to 2.65 GeV
The reaction \gamma p \TO K^+\Lambda(1520) was measured in the energy range
from threshold to 2.65 GeV with the SAPHIR detector at the electron stretcher
facility ELSA in Bonn. The production cross section was
analyzed in the decay modes , , , and
as a function of the photon energy and the squared
four-momentum transfer . While the cross sections for the inclusive
reactions rise steadily with energy, the cross section of the process \gamma p
\TO K^+\Lambda(1520) peaks at a photon energy of about 2.0 GeV, falls off
exponentially with , and shows a slope flattening with increasing photon
energy. The angular distributions in the -channel helicity system indicate
neither a nor a exchange dominance. The interpretation of the
as a molecule is not supported.Comment: 11 pages, 16 figures, 4 table
Role of the meson in photoproduction off the deuteron
Neutral kaon photoproduction off the nucleon and deuteron has been
reinvestigated by utilizing the new experimental data on both targets. An
isobar model for elementary operator and impulse approximation for the reaction
on the deuteron have been used. The available free parameters in the elementary
model have been extracted from both elementary and deuteron data. In contrast
to the elementary reaction, fitting the deuteron data requires an inclusion of
weighting factor. The result indicates that the angular distribution of the
elementary process does not show backward peaking behavior.Comment: 4 pages, 4 figures, prepared for the Fifth Asia-Pacific Conference on
Few-Body Problems in Physics 2011 (APFB2011), Seoul, Korea, August 22-26,
201
Gerasimov-Drell-Hearn Sum Rule and the Discrepancy between the New CLAS and SAPHIR Data
Contribution of the K^+\Lambda channel to the Gerasimov-Drell-Hearn (GDH) sum
rule has been calculated by using the models that fit the recent SAPHIR or CLAS
differential cross section data. It is shown that the two data sets yield quite
different contributions. Contribution of this channel to the forward spin
polarizability of the proton has been also calculated. It is also shown that
the inclusion of the recent CLAS C_x and C_z data in the fitting data base does
not significantly change the result of the present calculation. Results of the
fit, however, reveal the role of the S_{11}(1650), P_{11}(1710), P_{13}(1720),
and P_{13}(1900) resonances for the description of the C_x and C_z data. A
brief discussion on the importance of these resonances is given. Measurements
of the polarized total cross section \sigma_{TT'} by the CLAS, LEPS, and MAMI
collaborations are expected to verify this finding.Comment: 15 pages, 8 figure
Component-based programming for higher-order attribute grammars
This paper presents techniques for a component-based style of programming in the context of higher-oder attribute grammars (HAG). Attribute grammar components are "plugged in" into larger attribute grammar systems through higher-order attribute grammars. Higher-order attributes are used as (intermediate) "gluing" data structures.This paper also presents two attribute grammar components that can be re-used across different language-based tool specifications: a visualizer and animator of programs and a graphical user interface AG component. Both components are reused in the definition of a simple language processor. The techniques presented in this paper are implemented in LRC: a purely functional, higher-order attribute grammar-based system that generates language-based tools.(undefined
Study of nucleon resonances with electromagnetic interactions
Recent developments in using electromagnetic meson production reactions to
study the structure of nucleon resonances are reviewed. Possible future works
are discussed.Comment: 25 pages, 19 figure
High resolution amplitude and phase gratings in atom optics
An atom-field geometry is chosen in which an atomic beam traverses a field
interaction zone consisting of three fields, one having frequency propagating in the direction and the other two having
frequencies and propagating in the
- direction. For and , where and are positive integers and
is the pulse duration in the atomic rest frame, the atom-field interaction
results in the creation of atom amplitude and phase gratings having period . In this manner, one can use optical fields having
wavelength to produce atom gratings having periodicity much less
than .Comment: 11 pages, 14 figure
Measurement of gamma p --> K+ Lambda and gamma p --> K+ Sigma0 at photon energies up to 2.6 GeV
The reactions gamma p --> K+ Lambda and gamma p --> K+ Sigma0 were measured
in the energy range from threshold up to a photon energy of 2.6 GeV. The data
were taken with the SAPHIR detector at the electron stretcher facility, ELSA.
Results on cross sections and hyperon polarizations are presented as a function
of kaon production angle and photon energy. The total cross section for Lambda
production rises steeply with energy close to threshold, whereas the Sigma0
cross section rises slowly to a maximum at about E_gamma = 1.45 GeV. Cross
sections together with their angular decompositions into Legendre polynomials
suggest contributions from resonance production for both reactions. In general,
the induced polarization of Lambda has negative values in the kaon forward
direction and positive values in the backward direction. The magnitude varies
with energy. The polarization of Sigma0 follows a similar angular and energy
dependence as that of Lambda, but with opposite sign.Comment: 21 pages, 25 figures, submitted to Eur. Phys. J.
Quantum-state control in optical lattices
We study the means to prepare and coherently manipulate atomic wave packets
in optical lattices, with particular emphasis on alkali atoms in the
far-detuned limit. We derive a general, basis independent expression for the
lattice operator, and show that its off-diagonal elements can be tailored to
couple the vibrational manifolds of separate magnetic sublevels. Using these
couplings one can evolve the state of a trapped atom in a quantum coherent
fashion, and prepare pure quantum states by resolved-sideband Raman cooling. We
explore the use of atoms bound in optical lattices to study quantum tunneling
and the generation of macroscopic superposition states in a double-well
potential. Far-off-resonance optical potentials lend themselves particularly
well to reservoir engineering via well controlled fluctuations in the
potential, making the atom/lattice system attractive for the study of
decoherence and the connection between classical and quantum physics.Comment: 35 pages including 8 figures. To appear in Phys. Rev. A. March 199
K0-Sigma+ Photoproduction with SAPHIR
Preliminary results of the analysis of the reaction p(gamma,K0)Sigma+ are
presented. We show the first measurement of the differential cross section and
much improved data for the total cross section than previous data. The data are
compared with model predictions from different isobar and quark models that
give a good description of p(gamma,K+)Lambda and p(gamma,K+)Sigma0 data in the
same energy range. Results of ChPT describe the data adequately at threshold
while isobar models that include hadronic form factors reproduce the data at
intermediate energies.Comment: 4 pages, Latex2e, 4 postscript figures. Talk given at the
International Conference on Hypernuclear and Strange Particle Physics
(HYP97), Brookhaven National Laboratory, USA, October 13-18, 1997. To be
published in Nucl. Phys. A. Revised version due to changes in experimental
dat
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