716 research outputs found
A new integration algorithm for ordinary differential equations based on continued fraction approximations
A new integration algorithm is found, and an implementation is compared with other programmed algorithms. The new algorithm is a step by step procedure for solving the initial value problem in ordinary differential equations. It is designed to approximate poles of small integer order in the solutions of the differential equations by continued fractions obtained by manipulating the sums of truncated Taylor series expansions. The new method is compared with the Gragg- Bulirsch-Stoer, and the Taylor series method. The Taylor series method and the new method are shown to be superior in speed and accuracy, while the new method is shown to be most superior when the solution is required near a singularity. The new method can finally be seen to pass automatically through singularities where all the other methods which are discussed will have failed
Database independent Migration of Objects into an Object-Relational Database
This paper reports on the CERN-based WISDOM project which is studying the
serialisation and deserialisation of data to/from an object database
(objectivity) and ORACLE 9i.Comment: 26 pages, 18 figures; CMS CERN Conference Report cr02_01
Higher Fertilizer Inputs Increase Fitness Traits of Brown Planthopper in Rice.
Rice (Oryza sativa L.) is the primary staple food source for more than half of the world's population. In many developing countries, increased use of fertilizers is a response to increase demand for rice. In this study, we investigated the effects of three principal fertilizer components (nitrogen, phosphorus and potassium) on the development of potted rice plants and their effects on fitness traits of the brown planthopper (BPH) [Nilaparvata lugens (Stål) (Homoptera: Delphacidae)], which is a major pest of rice in Bangladesh and elsewhere. Compared to low fertilizer inputs, high fertilizer treatments induced plant growth but also favored BPH development. The BPH had higher survival, developed faster, and the intrinsic rate of natural increase (r m ) was higher on well-fertilized than under-fertilized plants. Among the fertilizer inputs, nitrogen had the strongest effect on the fitness traits of BPH. Furthermore, both the "Plant vigor hypothesis" and the "Plant stress hypothesis" were supported by the results, the former hypothesis more so than the latter. These hypotheses suggest that the most suitable/attractive hosts for insect herbivores are the most vigorous plants. Our findings emphasized that an exclusive focus on yield increases through only enhanced crop fertilization may have unforeseen, indirect, effects on crop susceptibility to pests, such as BPH
Dynamic wetting with two competing adsorbates
We study the dynamic properties of a model for wetting with two competing
adsorbates on a planar substrate. The two species of particles have identical
properties and repel each other. Starting with a flat interface one observes
the formation of homogeneous droplets of the respective type separated by
nonwet regions where the interface remains pinned. The wet phase is
characterized by slow coarsening of competing droplets. Moreover, in 2+1
dimensions an additional line of continuous phase transition emerges in the
bound phase, which separates an unordered phase from an ordered one. The
symmetry under interchange of the particle types is spontaneously broken in
this region and finite systems exhibit two metastable states, each dominated by
one of the species. The critical properties of this transition are analyzed by
numeric simulations.Comment: 11 pages, 12 figures, final version published in PR
Mobile Computing in Physics Analysis - An Indicator for eScience
This paper presents the design and implementation of a Grid-enabled physics
analysis environment for handheld and other resource-limited computing devices
as one example of the use of mobile devices in eScience. Handheld devices offer
great potential because they provide ubiquitous access to data and
round-the-clock connectivity over wireless links. Our solution aims to provide
users of handheld devices the capability to launch heavy computational tasks on
computational and data Grids, monitor the jobs status during execution, and
retrieve results after job completion. Users carry their jobs on their handheld
devices in the form of executables (and associated libraries). Users can
transparently view the status of their jobs and get back their outputs without
having to know where they are being executed. In this way, our system is able
to act as a high-throughput computing environment where devices ranging from
powerful desktop machines to small handhelds can employ the power of the Grid.
The results shown in this paper are readily applicable to the wider eScience
community.Comment: 8 pages, 7 figures. Presented at the 3rd Int Conf on Mobile Computing
& Ubiquitous Networking (ICMU06. London October 200
Scalar radius of the pion in the Kroll-Lee-Zumino renormalizable theory
The Kroll-Lee-Zumino renormalizable Abelian quantum field theory of pions and
a massive rho-meson is used to calculate the scalar radius of the pion at next
to leading (one loop) order in perturbation theory. Due to renormalizability,
this determination involves no free parameters. The result is . This value gives for , the low energy constant of
chiral perturbation theory, , and , where F
is the pion decay constant in the chiral limit. Given the level of accuracy in
the masses and the coupling, the only sizable uncertainty in this
result is due to the (uncalculated) NNLO contribution
Pion form factor in the Kroll-Lee-Zumino model
The renormalizable Abelian quantum field theory model of Kroll, Lee, and
Zumino is used to compute the one-loop vertex corrections to the tree-level,
Vector Meson Dominance (VMD) pion form factor. These corrections, together with
the known one-loop vacuum polarization contribution, lead to a substantial
improvement over VMD. The resulting pion form factor in the space-like region
is in excellent agreement with data in the whole range of accessible momentum
transfers. The time-like form factor, known to reproduce the Gounaris-Sakurai
formula at and near the rho-meson peak, is unaffected by the vertex correction
at order (g_\rpp^2).Comment: Revised version corrects a misprint in Eq.(1
Design Patterns for Description-Driven Systems
In data modelling, product information has most often been handled separately
from process information. The integration of product and process models in a
unified data model could provide the means by which information could be shared
across an enterprise throughout the system lifecycle from design through to
production. Recently attempts have been made to integrate these two separate
views of systems through identifying common data models. This paper relates
description-driven systems to multi-layer architectures and reveals where
existing design patterns facilitate the integration of product and process
models and where patterns are missing or where existing patterns require
enrichment for this integration. It reports on the construction of a so-called
description-driven system which integrates Product Data Management (PDM) and
Workflow Management (WfM) data models through a common meta-model.Comment: 14 pages, 13 figures. Presented at the 3rd Enterprise Distributed
Object Computing EDOC'99 conference. Mannheim, Germany. September 199
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