6,757 research outputs found
On the Geographic Allocation of Open Source Software Activities
Open source software (OSS) is marked by free access to the software and its source code. OSS is developed by a 'community' consisting of thousands of contributors from all over the world. Some research was undertaken in order to analyze how global the OSS community actually is, i.e. analyze the geographic origin of OSS developers. But as members of the OSS community differ in their activity levels, information about the allocation of activities are of importance. Our paper contributes to this as we analyze not only the geographic origin of (active) developers but also the geographic allocation of OSS activities. The paper is based on data from the SourceForge research Data Archive, referring to 2006. We exploit information about the developers' IP address, email address and indicated time-zone. This enables us to properly assign 1.3 million OSS developers from SourceForge to their countries, that are 94% of all registered ones in 2006. In addition we have information about the number of posted messages which is a good proxy for activity of each developer. Thus we can provide a detailed picture of the world-wide allocation of open source activities. Such country data about the supply-side of OSS is a valuable stock for both, cross-country studies on OSS, as well as country-specific research and policy advice.Open Source Software, Geographical Location, Open Source Activities
Monte Carlo event generator validation and tuning for the LHC
We summarise the motivation for, and the status of, the tools developed by
CEDAR/MCnet for validating and tuning Monte Carlo event generators for the LHC
against data from previous colliders. We then present selected preliminary
results from studies of event shapes and hadronisation observables from e+e-
colliders, and of minimum bias and underlying event observables from the
Tevatron, and comment on the approach needed with early LHC data to best
exploit the potential for new physics discoveries at the LHC in the next few
years.Comment: Prepared for Proceedings of XII Advanced Computing and Analysis
Techniques in Physics Research, November 3-7 2008, Erice, Ital
The Effects of Function-Based Antecedent and Consequent Interventions for Increasing Appropriate Behavior and Decreasing Disruptive Behavior of Preschool Students in the School Setting
The Functional Behavior Assessment (FBA) literature suggests that functionbased interventions are effective at improving problem behavior for individuals in a variety of settings. However, the FBA literature is limited in the number of studies that examine the relative effectiveness of function-based antecedent and consequent interventions for reducing problem behavior and increasing appropriate replacement behaviors. Additionally, while there has been a recent increase in the number of studies conducted in the school setting, only a limited number of studies include children in the preschool setting. The purpose of the present study was to extend the literature by examining the relative effectiveness of function-based antecedent and consequent interventions for reducing problem behavior and increasing appropriate replacement behavior for preschool children of typical development. The following study included four preschool-age children. Following a functional behavior assessment, the relative effectiveness of a function-based antecedent and consequent intervention was examined using an alternating treatments design (ATD). Results indicate that both the function based antecedent intervention and consequent intervention were effective at decreasing problem behavior and increasing appropriately engaged behavior, with the function-based antecedent intervention being more effective than the function-based consequent intervention for two of the four participants
Efficient Process-to-Node Mapping Algorithms for Stencil Computations
Good process-to-compute-node mappings can be decisive for well performing HPC
applications. A special, important class of process-to-node mapping problems is
the problem of mapping processes that communicate in a sparse stencil pattern
to Cartesian grids. By thoroughly exploiting the inherently present structure
in this type of problem, we devise three novel distributed algorithms that are
able to handle arbitrary stencil communication patterns effectively. We analyze
the expected performance of our algorithms based on an abstract model of inter-
and intra-node communication. An extensive experimental evaluation on several
HPC machines shows that our algorithms are up to two orders of magnitude faster
in running time than a (sequential) high-quality general graph mapping tool,
while obtaining similar results in communication performance. Furthermore, our
algorithms also achieve significantly better mapping quality compared to
previous state-of-the-art Cartesian grid mapping algorithms. This results in up
to a threefold performance improvement of an MPI_Neighbor_alltoall exchange
operation. Our new algorithms can be used to implement the MPI_Cart_create
functionality.Comment: 18 pages, 9 Figure
Fluorescence correlation spectroscopy in thin films at reflecting substrates as a means to study nanoscale structure and dynamics at soft-matter interfaces
Structure and dynamics at soft-matter interfaces play an important role in
nature and technical applications. Optical single-molecule investigations are
non-invasive and capable to reveal heterogeneities at the nanoscale. In this
work we develop an autocorrelation function (ACF) approach to retrieve tracer
diffusion parameters obtained from fluorescence correlation spectroscopy (FCS)
experiments in thin liquid films at reflecting substrates. This approach then
is used to investigate structure and dynamics in 100 nm thick 8CB liquid
crystal films on silicon wafers with five different oxide thicknesses. We find
a different extension of the structural reorientation of 8CB at the
solid-liquid interface for thin and for thick oxide. For the thin oxides, the
perylenediimide tracer diffusion dynamics in general agrees with the
hydrodynamic modeling using no-slip boundary conditions with only a small
deviation close to the substrate, while a considerably stronger decrease of the
interfacial tracer diffusion is found for the thick oxides.Comment: 8 figure
New developments in event generator tuning techniques
Data analyses in hadron collider physics depend on background simulations
performed by Monte Carlo (MC) event generators. However, calculational
limitations and non-perturbative effects require approximate models with
adjustable parameters. In fact, we need to simultaneously tune many
phenomenological parameters in a high-dimensional parameter-space in order to
make the MC generator predictions fit the data. It is desirable to achieve this
goal without spending too much time or computing resources iterating parameter
settings and comparing the same set of plots over and over again. We present
extensions and improvements to the MC tuning system, Professor, which addresses
the aforementioned problems by constructing a fast analytic model of a MC
generator which can then be easily fitted to data. Using this procedure it is
for the first time possible to get a robust estimate of the uncertainty of
generator tunings. Furthermore, we can use these uncertainty estimates to study
the effect of new (pseudo-) data on the quality of tunings and therefore decide
if a measurement is worthwhile in the prospect of generator tuning. The
potential of the Professor method outside the MC tuning area is presented as
well.Comment: To appear in the proceedings of the 13th International Workshop on
Advanced Computing and Analysis Techniques in Physics Research, ACAT2010,
Jaipur, India, February 22-27, 201
Role of cardiovascular magnetic resonance in the guidelines of the European Society of Cardiology
BACKGROUND: Despite common enthusiasm for cardiovascular magnetic resonance (CMR), its application in Europe is quite diverse. Restrictions are attributed to a number of factors, like limited access, deficits in training, and incomplete reimbursement. Aim of this study is to perform a systematic summary of the representation of CMR in the guidelines of the European Society of Cardiology (ESC). METHODS: Twenty-nine ESC guidelines were screened for the terms "magnetic", "MRI", "CMR", "MR" and "imaging". As 3 topics were published twice (endocarditis, pulmonary hypertension, NSTEMI), 26 guidelines were finally included. MRI in the context of non-cardiovascular examinations was not recognized. The main CMR-related conclusions and, if available, the level of evidence and the class of recommendation were extracted. RESULTS: Fourteen of the 26 guidelines (53.8 %) contain specific recommendations regarding the use of CMR. Nine guidelines (34.6 %) mention CMR in the text, and 3 (11.5 %) do not mention CMR. The 14 guidelines with recommendations regarding the use of CMR contain 39 class-I recommendations, 12 class-IIa recommendations, 10 class-IIb recommendations and 2 class-III recommendations. Most of the recommendations have evidence level C (41/63; 65.1 %), followed by level B (16/63; 25.4 %) and level A (6/63; 9.5 %). The four guidelines, which absolutely contained most recommendations for CMR, were stable coronary artery disease (n = 14), aortic diseases (n = 9), HCM (n = 7) and myocardial revascularization (n = 7). CONCLUSIONS: CMR is represented in the majority of the ESC guidelines. They contain many recommendations in favour of the use of CMR in specific scenarios. Issues regarding access, training and reimbursement have to be solved to offer CMR to patients in accordance with the ESC guidelines
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