128 research outputs found
RadioPropa - A Modular Raytracer for In-Matter Radio Propagation
Experiments for radio detection of UHE particles such as e.g. ARA/ARIANNA or
NuMoon require detailed understanding of the propagation of radio waves in the
surrounding matter. The index of refraction in e.g. polar ice or lunar rock may
have a complex spatial structure that makes detailed simulations of the radio
propagation necessary to design the respective experiments and analyze their
data. Here, we present RadioPropa as a new modular ray tracing code that solves
the eikonal equation with a Runge-Kutta method in arbitrary refractivity
fields. RadioPropa is based on the cosmic ray propagation code CRPropa, which
has been forked to allow efficient incorporation of the required data
structures for ray tracing while retaining its modular design. This allows for
the setup of versatile simulation geometries as well as the easy inclusion of
additional physical effects such as e.g. partial reflection on boundary layers
in the simulations. We discuss the principal design of the code as well as its
performance in example applications.Comment: Proceedings of the ARENA Conference 201
Detecting Local Deflection Patterns of Ultra-high Energy Cosmic Rays using the Principal Axes of the Directional Energy Distribution
From deflections in galactic and extragalactic magnetic fields energy
dependent structures in the arrival directions of ultra-high energy cosmic rays
(UHECR) are expected. We propose to characterize these structures by the
strength of collimation of energy along the principal axes in selected regions
in the sky. While the strength of collimation are indicators of anisotropy in
the arrival distribution of UHECR, the orientation of the principal system
holds information about the direction of the deflections of UHECR. We discuss
the method and present expected limits on the strength of deflection and
density of sources using simulated scenarios of UHECR proton propagation.Comment: Contribution no. 1063 to the 33rd International Cosmic Ray
Conference, Rio de Janeiro, Brazil, July 201
PARSEC: A Parametrized Simulation Engine for Ultra-High Energy Cosmic Ray Protons
We present a new simulation engine for fast generation of ultra-high energy
cosmic ray data based on parametrizations of common assumptions of UHECR origin
and propagation. Implemented are deflections in unstructured turbulent
extragalactic fields, energy losses for protons due to photo-pion production
and electron-pair production, as well as effects from the expansion of the
universe. Additionally, a simple model to estimate propagation effects from
iron nuclei is included. Deflections in galactic magnetic fields are included
using a matrix approach with precalculated lenses generated from backtracked
cosmic rays. The PARSEC program is based on object oriented programming
paradigms enabling users to extend the implemented models and is steerable with
a graphical user interface.Comment: 10 pages, 6 figures, accepted for publication in Astroparticle
Physic
Cosmic ray propagation with CRPropa 3
Solving the question of the origin of ultra-high energy cosmic rays (UHECRs)
requires the development of detailed simulation tools in order to interpret the
experimental data and draw conclusions on the UHECR universe. CRPropa is a
public Monte Carlo code for the galactic and extragalactic propagation of
cosmic ray nuclei above eV, as well as their photon and neutrino
secondaries. In this contribution the new algorithms and features of CRPropa 3,
the next major release, are presented. CRPropa 3 introduces time-dependent
scenarios to include cosmic evolution in the presence of cosmic ray deflections
in magnetic fields. The usage of high resolution magnetic fields is facilitated
by shared memory parallelism, modulated fields and fields with heterogeneous
resolution. Galactic propagation is enabled through the implementation of
galactic magnetic field models, as well as an efficient forward propagation
technique through transformation matrices. To make use of the large Python
ecosystem in astrophysics CRPropa 3 can be steered and extended in Python.Comment: 16th International workshop on Advanced Computing and Analysis
Techniques in physics research (ACAT 2014) proceedings, 6 pages, 6 figure
CRPropa 3.0 - a Public Framework for Propagating UHE Cosmic Rays through Galactic and Extragalactic Space
The interpretation of experimental data of ultra-high energy cosmic rays
(UHECRs) above 10^17 eV is still under controversial debate. The development
and improvement of numerical tools to propagate UHECRs in galactic and
extragalactic space is a crucial ingredient to interpret data and to draw
conclusions on astrophysical parameters. In this contribution the next major
release of the publicly available code CRPropa (3.0) is presented. It reflects
a complete redesign of the code structure to facilitate high performance
computing and comprises new physical features such as an interface for galactic
propagation using lensing techniques and inclusion of cosmological effects in a
three-dimensional environment. The performance is benchmarked and first
applications are presented.Comment: 4 pages, 3 figures. Proceedings of the 33rd International Cosmic Ray
Conference (ICRC), Rio de Janeiro, Brazil, 2-9 July 201
Cyclooxygenase 2: understanding the pathophysiological role through genetically altered mouse models
El pdf del artÃculo es la versión post-print.Cyclooxygenase (COX) -1 and –2 catalyze the first step in the biosynthesis of prostanoids. COX-1 is constitutively expressed in many tissues and seems to be involved in the house keeping function of prostanoids. COX-2, the inducible isoform, accounts for the elevated production of prostaglandins in response to various inflammatory stimuli, hormones and growth factors. COX-2 expression has been also associated with cell growth regulation, tissue remodelling and carcinogenesis. More of these characteristics have been elucidate through using COX selective inhibitors. Recent advances in transgenic and gene-targeting approaches allow a sophisticated manipulation of the mouse genome by gene addition, gene deletion or gene modifications. The development of COX-2 genetically altered mice has provided models to elucidate the physiological and pathophysiological roles of this enzyme.This work was supported by grants from Instituto de Salud Carlos III (Red de Centros C03/01), Generalitat Valenciana (GRUPOS03/072), Ministerio de Educación y Ciencia (SAF2004-00957) and Comunidad de Madrid (CAM2004-GR/SAL/0388).Peer reviewe
A field study of data analysis exercises in a bachelor physics course using the internet platform VISPA
Bachelor physics lectures on particle physics and astrophysics were
complemented by exercises related to data analysis and data interpretation at
the RWTH Aachen University recently. The students performed these exercises
using the internet platform VISPA, which provides a development environment for
physics data analyses. We describe the platform and its application within the
physics course, and present the results of a student survey. The students
acceptance of the learning project was positive. The level of acceptance was
related to their individual preference for learning with a computer.
Furthermore, students with good programming skills favor working individually,
while students who attribute themselves having low programming abilities favor
working in teams. The students appreciated approaching actual research through
the data analysis tasks.Comment: 21 pages, 8 figures, 1 table, for the internet platform VISPA see
http://vispa.physik.rwth-aachen.d
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