1,477,381 research outputs found
Hidden parameters in open-system evolution unveiled by geometric phase
We find a class of open-system models in which individual quantum
trajectories may depend on parameters that are undetermined by the full
open-system evolution. This dependence is imprinted in the geometric phase
associated with such trajectories and persists after averaging. Our findings
indicate a potential source of ambiguity in the quantum trajectory approach to
open quantum systems.Comment: QSD analysis added; several stylistic changes; journal reference
adde
Towards a compendium of process technologies: The jBPT library for process model analysis
This paper presents the idea of a compendium of process technologies, i.e., a concise but comprehensive collection of techniques for process model analysis that support research on the design, execution, and evaluation of processes. The idea originated from observations on the evolution of process-related research disciplines. Based on these observations, we derive design goals for a compendium. Then, we present the jBPT library, which addresses these goals by means of an implementation of common analysis techniques in an open source codebase
Concepts, Developments and Advanced Applications of the PAX Toolkit
The Physics Analysis eXpert (PAX) is an open source toolkit for high energy
physics analysis. The C++ class collection provided by PAX is deployed in a
number of analyses with complex event topologies at Tevatron and LHC. In this
article, we summarize basic concepts and class structure of the PAX kernel. We
report about the most recent developments of the kernel and introduce two new
PAX accessories. The PaxFactory, that provides a class collection to facilitate
event hypothesis evolution, and VisualPax, a Graphical User Interface for PAX
objects
Observational properties of the open cluster system of the Milky Way and what they tell us about our Galaxy
Almost 80 years have passed since Trumpler's analysis of the Galactic open
cluster system laid one of the main foundations for understanding the nature
and structure of the Milky Way. Since then, the open cluster system has been
recognised as a key source of information for addressing a wide range of
questions about the structure and evolution of our Galaxy. Over the last
decade, surveys and individual observations from the ground and space have led
to an explosion of astrometric, kinematic and multiwavelength photometric and
spectroscopic open cluster data. In addition, a growing fraction of these data
is often time-resolved. Together with increasing computing power and
developments in classification techniques, the open cluster system reveals an
increasingly clearer and more complete picture of our Galaxy. In this
contribution, I review the observational properties of the Milky Way's open
cluster system. I discuss what they can and cannot teach us now and in the near
future about several topics such as the Galaxy's spiral structure and dynamics,
chemical evolution, large-scale star formation, stellar populations and more.Comment: 11 pages, 3 figures, to appear in proc. IAUS 266 "Star clusters:
basic galactic building blocks "(eds. R. de Grijs, J. R. D. Lepine
SYGMA: Stellar Yields for Galactic Modeling Applications
The stellar yields for galactic modeling applications (SYGMA) code is an
open-source module that models the chemical ejecta and feedback of simple
stellar populations (SSPs). It is intended for use in hydrodynamical
simulations and semi-analytic models of galactic chemical evolution. The module
includes the enrichment from asymptotic giant branch (AGB) stars, massive
stars, SNIa and neutron-star mergers. An extensive and extendable stellar
yields library includes the NuGrid yields with all elements and many isotopes
up to Bi. Stellar feedback from mechanic and frequency-dependent radiative
luminosities are computed based on NuGrid stellar models and their synthetic
spectra. The module further allows for customizable initial-mass functions and
supernova Ia (SNIa) delay-time distributions to calculate time-dependent ejecta
based on stellar yield input. A variety of r-process sites can be included. A
comparison of SSP ejecta based on NuGrid yields with those from Portinari et
al. (1998) and Marigo (2001) reveals up to a factor of 3.5 and 4.8 less C and N
enrichment from AGB stars at low metallicity, a result we attribute to NuGrid's
modeling of hot-bottom burning. Different core-collapse supernova explosion and
fallback prescriptions may lead to substantial variations for the accumulated
ejecta of C, O and Si in the first at . An online
interface of the open-source SYGMA module enables interactive simulations,
analysis and data extraction of the evolution of all species formed by the
evolution of simple stellar populations.Comment: 18 pages, 10 figures, 3 tables, published in ApJ
Open-Source PC-Based Software Routers: a Viable Approach to High-Performance Packet Switching
Abstract. We consider IP routers based on off-the-shelf personal computer (PC) hardware running the Linux open-source operating system. The choice of building IP routers with off-the-shelf hardware stems from the wide availability of documentation, the low cost associated with large-scale production, and the continuous evolution driven by the market. On the other hand, open-source software provides the opportunity to easily modify the router operation so as to suit every need. The main contribution of the paper is the analysis of the performance bottlenecks of PC-based open-source software routers and the evaluation of the solutions currently available to overcome them.
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