3,660 research outputs found
An Overview of a Grid Architecture for Scientific Computing
This document gives an overview of a Grid testbed architecture proposal for
the NorduGrid project. The aim of the project is to establish an inter-Nordic
testbed facility for implementation of wide area computing and data handling.
The architecture is supposed to define a Grid system suitable for solving data
intensive problems at the Large Hadron Collider at CERN. We present the various
architecture components needed for such a system. After that we go on to give a
description of the dynamics by showing the task flow
The NorduGrid architecture and tools
The NorduGrid project designed a Grid architecture with the primary goal to
meet the requirements of production tasks of the LHC experiments. While it is
meant to be a rather generic Grid system, it puts emphasis on batch processing
suitable for problems encountered in High Energy Physics. The NorduGrid
architecture implementation uses the \globus{} as the foundation for various
components, developed by the project. While introducing new services, the
NorduGrid does not modify the Globus tools, such that the two can eventually
co-exist. The NorduGrid topology is decentralized, avoiding a single point of
failure. The NorduGrid architecture is thus a light-weight, non-invasive and
dynamic one, while robust and scalable, capable of meeting most challenging
tasks of High Energy Physics.Comment: Talk from the 2003 Computing in High Energy Physics and Nuclear
Physics (CHEP03), La Jolla, Ca, USA, March 2003, 9 pages,LaTeX, 4 figures.
PSN MOAT00
Atlas Data-Challenge 1 on NorduGrid
The first LHC application ever to be executed in a computational Grid
environment is the so-called ATLAS Data-Challenge 1, more specifically, the
part assigned to the Scandinavian members of the ATLAS Collaboration. Taking
advantage of the NorduGrid testbed and tools, physicists from Denmark, Norway
and Sweden were able to participate in the overall exercise starting in July
2002 and continuing through the rest of 2002 and the first part of 2003 using
solely the NorduGrid environment. This allowed to distribute input data over a
wide area, and rely on the NorduGrid resource discovery mechanism to find an
optimal cluster for job submission. During the whole Data-Challenge 1, more
than 2 TB of input data was processed and more than 2.5 TB of output data was
produced by more than 4750 Grid jobs.Comment: Talk from the 2003 Computing in High Energy Physics and Nuclear
Physics (CHEP03), La Jolla, Ca, USA, March 2003, 7 pages, 3 ps figure
The propensity of molecules to spatially align in intense light fields
The propensity of molecules to spatially align along the polarization vector
of intense, pulsed light fields is related to readily-accessible parameters
(molecular polarizabilities, moment of inertia, peak intensity of the light and
its pulse duration). Predictions can now be made of which molecules can be
spatially aligned, and under what circumstances, upon irradiation by intense
light. Accounting for both enhanced ionization and hyperpolarizability, it is
shown that {\it all} molecules can be aligned, even those with the smallest
static polarizability, when subjected to the shortest available laser pulses
(of sufficient intensity).Comment: 8 pages, 4 figures, to be submitted to PR
Rotational diversity effects in a triticale-based cropping system
Research indicates that not all crops respond similarly to cropping diversity and the response of triticale (× Triticosecale ssp.) has not been documented. We investigated the effects of rotational diversity on cereals in cropping sequences with canola (Brassica napus L.), field pea (Pisum sativum L.), or an intercrop (triticale:field pea). Six crop rotations were established consisting of two, 2-yr low diversity rotations (LDR) (continuous triticale (T-T_LDR) and triticale-wheat (Triticum aestivum L.) (T-W_LDR)); three, 2-yr moderate diversity rotations (MDR) (triticale-field pea (T-P_MDR), triticale-canola (T-C_MDR), and a triticale: field pea intercrop (T- in P_MDR)); and one, 3-yr high diversity rotation (HDR) (canola-triticale-field pea (C-T-P_HDR)). The study was established in Lethbridge, Alberta (irrigated and rainfed); Swift Current (rainfed) and Canora (rainfed), Saskatchewan, Canada; and carried out from 2008 to 2014. Triticale grain yield for the 3-yr HDR was superior over the LDR rotations and the MDR triticale-field pea system; however, results were similar for triticale-canola, and removal of canola from the system caused a yield drag in triticale. Triticale biomass was superior for the 3-yr HDR. Moreover, along with improved triticale grain yield, the 3-yr HDR provided greater yield stability across environments. High rotational diversity (C-T-P_HDR) resulted in the highest soil microbial community and soil carbon concentration, whereas continuous triticale provided the lowest. Net economic returns were also superior for C-T-P_HDR (458 ha–1). Overall, triticale responded positively to increased rotational diversity and displayed greater stability with the inclusion of field pea, leading to improved profitability and sustainability of the system
Ionic structure and photoabsorption in medium sized sodium clusters
We present ground-state configurations and photoabsorption spectra of Na-7+,
Na-27+ and Na-41+. Both the ionic structure and the photoabsorption spectra of
medium-size sodium clusters beyond Na-20 have been calculated self-consistently
with a nonspherical treatment of the valence electrons in density functional
theory. We use a local pseudopotential that has been adjusted to experimental
bulk properties and the atomic 3s level of sodium. Our studies have shown that
both the ionic structure of the ground state and the positions of the plasmon
resonances depend sensitively on the pseudopotential used in the calculation,
which stresses the importance of its consistent use in both steps.Comment: 4 pages, 3 figures. Accepted for publication in PRB, tentatively July
15th, 1998 some typos corrected, brought to nicer forma
Classification of phase transitions in small systems
We present a classification scheme for phase transitions in finite systems
like atomic and molecular clusters based on the Lee-Yang zeros in the complex
temperature plane. In the limit of infinite particle numbers the scheme reduces
to the Ehrenfest definition of phase transitions and gives the right critical
indices. We apply this classification scheme to Bose-Einstein condensates in a
harmonic trap as an example of a higher order phase transitions in a finite
system and to small Ar clusters.Comment: 12 pages, 4 figures, accepted for publication in Phys. Rev. Let
Chemistry of layered d-metal pnictide oxides and their potential as candidates for new superconductors
Layered d-metal pnictide oxides are a unique class of compounds which
consists of characteristic d-metal pnictide layers and metal oxide layers. More
than 100 of these layered compounds, including the recently discovered Fe-based
superconducting pnictide oxides, can be classified into 9 structure types.
These structure types and the chemical and physical properties of the
characteristic d-metal pnictide layers and metal oxide layers of the layered
d-metal pnictide oxides are reviewed and discussed. Furthermore, possible
approaches to design new superconductors based on these layered d-metal
pnictide oxides are proposed.Comment: 29 pages including 6 tables and 2 figure
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