388 research outputs found
LSST optical beam simulator
We describe a camera beam simulator for the LSST which is capable of
illuminating a 60mm field at f/1.2 with realistic astronomical scenes, enabling
studies of CCD astrometric and photometric performance. The goal is to fully
simulate LSST observing, in order to characterize charge transport and other
features in the thick fully depleted CCDs and to probe low level systematics
under realistic conditions. The automated system simulates the centrally
obscured LSST beam and sky scenes, including the spectral shape of the night
sky. The doubly telecentric design uses a nearly unit magnification design
consisting of a spherical mirror, three BK7 lenses, and one beam-splitter
window. To achieve the relatively large field the beam-splitter window is used
twice. The motivation for this LSST beam test facility was driven by the need
to fully characterize a new generation of thick fully-depleted CCDs, and assess
their suitability for the broad range of science which is planned for LSST. Due
to the fast beam illumination and the thick silicon design [each pixel is 10
microns wide and over 100 microns deep] at long wavelengths there can be
effects of photon transport and charge transport in the high purity silicon.
The focal surface covers a field more than sufficient for a 40x40 mm LSST CCD.
Delivered optical quality meets design goals, with 50% energy within a 5 micron
circle. The tests of CCD performance are briefly described.Comment: 9 pages, 9 figure
On the relativistic field theory model of the deuteron II
The relativistic field theory model of the deuteron is applied to the
calculation of the cross sections of the low-energy radiative neutron-proton
capture n + p -> D + gamma and the low-energy two-proton fusion p + p -> D +
e^+ + nu_e. For the low-energy radiative neutron-proton capture n + p -> D +
gamma our result agrees well with both the experimental data and the potential
model prediction. In the case of the two-proton fusion the cross section
obtained is 2.9 times as much as that given by the potential approach. The
obtained result is discussed in connection with the solar neutrino problem.
ERRATUM: We correct the value of the cross section for pp-fusion p + p -> D +
e^+ + nu_e. We find a contribution to the astrophysical factor \delta S_pp(0) =
2.01 x 10^{-25} (1 +/- 0.30) MeV b which is obtained only due to weak and
strong low-energy interactions of the protons and the deuteron when neglecting
the Coulomb repulsion between protons in the intermediate state. Minor
misprints are corrected.Comment: 35 pages, LaTeX, plus 5 figures added as postscript files, ERRATUM: 3
pages, to appear in Nucl. Phys. A added at the en
Rascal: From Algebraic Specification to Meta-Programming
Algebraic specification has a long tradition in bridging the gap between
specification and programming by making specifications executable. Building on
extensive experience in designing, implementing and using specification
formalisms that are based on algebraic specification and term rewriting (namely
Asf and Asf+Sdf), we are now focusing on using the best concepts from algebraic
specification and integrating these into a new programming language: Rascal.
This language is easy to learn by non-experts but is also scalable to very
large meta-programming applications.
We explain the algebraic roots of Rascal and its main application areas:
software analysis, software transformation, and design and implementation of
domain-specific languages. Some example applications in the domain of
Model-Driven Engineering (MDE) are described to illustrate this.Comment: In Proceedings AMMSE 2011, arXiv:1106.596
From foe to friend: using animal toxins to investigate ion channel function
Ion channels are vital contributors to cellular communication in a wide range of organisms, a distinct feature that renders this ubiquitous family of membrane-spanning proteins a prime target for toxins found in animal venom. For many years, the unique properties of these naturally-occurring molecules have enabled researchers to probe the structural and functional features of ion channels and to define their physiological roles in normal and diseased tissues. To illustrate their considerable impact on the ion channel field, this review will highlight fundamental insights into toxin-channel interactions as well as recently developed toxin screening methods and practical applications of engineered toxins
On the S-wave piD-scattering length in the relativistic field theory model of the deuteron
The S-wave scattering length of the strong pion-deuteron (pi D) scattering is
calculated in the relativistic field theory model of the deuteron suggested in
[1,2].The theoretical result agrees well with the experimental data. The
important role of the Delta-resonance contribution to the elastic pi
D-scattering is confirmed.Comment: 7 pages, no figures, accepted for publication in Z. Phys.
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