478 research outputs found
XML for Domain Viewpoints
Within research institutions like CERN (European Organization for Nuclear
Research) there are often disparate databases (different in format, type and
structure) that users need to access in a domain-specific manner. Users may
want to access a simple unit of information without having to understand detail
of the underlying schema or they may want to access the same information from
several different sources. It is neither desirable nor feasible to require
users to have knowledge of these schemas. Instead it would be advantageous if a
user could query these sources using his or her own domain models and
abstractions of the data. This paper describes the basis of an XML (eXtended
Markup Language) framework that provides this functionality and is currently
being developed at CERN. The goal of the first prototype was to explore the
possibilities of XML for data integration and model management. It shows how
XML can be used to integrate data sources. The framework is not only applicable
to CERN data sources but other environments too.Comment: 9 pages, 6 figures, conference report from SCI'2001 Multiconference
on Systemics & Informatics, Florid
Intrinsic and extrinsic x-ray absorption effects in soft x-ray diffraction from the superstructure in magnetite
We studied the (001/2) diffraction peak in the low-temperature phase of
magnetite (Fe3O4) using resonant soft x-ray diffraction (RSXD) at the Fe-L2,3
and O-K resonance. We studied both molecular-beam-epitaxy (MBE) grown thin
films and in-situ cleaved single crystals. From the comparison we have been
able to determine quantitatively the contribution of intrinsic absorption
effects, thereby arriving at a consistent result for the (001/2) diffraction
peak spectrum. Our data also allow for the identification of extrinsic effects,
e.g. for a detailed modeling of the spectra in case a "dead" surface layer is
present that is only absorbing photons but does not contribute to the
scattering signal.Comment: to appear in Phys. Rev.
A database for on-line event analysis on a distributed memory machine
Parallel in-memory databases can enhance the structuring and parallelization of programs used in High Energy Physics (HEP). Efficient database access routines are used as communication primitives which hide the communication topology in contrast to the more explicit communications like PVM or MPI. A parallel in-memory database, called SPIDER, has been implemented on a 32 node Meiko CS-2 distributed memory machine. The spider primitives generate a lower overhead than the one generated by PVM or PMI. The event reconstruction program, CPREAD of the CPLEAR experiment, has been used as a test case. Performance measurerate generated by CPLEAR
Object Serialization and Deserialization Using XML
Interoperability of potentially heterogeneous databases has been an ongoing
research issue for a number of years in the database community. With the trend
towards globalization of data location and data access and the consequent
requirement for the coexistence of new data stores with legacy systems, the
cooperation and data interchange between data repositories has become
increasingly important. The emergence of the eXtensible Markup Language (XML)
as a database independent representation for data offers a suitable mechanism
for transporting data between repositories. This paper describes a research
activity within a group at CERN (called CMS) towards identifying and
implementing database serialization and deserialization methods that can be
used to replicate or migrate objects across the network between CERN and
worldwide centres using XML to serialize the contents of multiple objects
resident in object-oriented databases.Comment: 14 pages 7 figure
CeRuSn: a strongly correlated material with nontrivial topology
Topological insulators form a novel state of matter that provides new
opportunities to create unique quantum phenomena. While the materials used so
far are based on semiconductors, recent theoretical studies predict that also
strongly correlated systems can show non-trivial topological properties,
thereby allowing even the emergence of surface phenomena that are not possible
with topological band insulators. From a practical point of view, it is also
expected that strong correlations will reduce the disturbing impact of defects
or impurities, and at the same increase the Fermi velocities of the topological
surface states. The challenge is now to discover such correlated materials.
Here, using advanced x-ray spectroscopies in combination with band structure
calculations, we infer that CeRuSn is a strongly correlated material
with non-trivial topology.Comment: 10 pages, 6 figures, submitted to Scientific Report
High resolution exposure modelling of heat and air pollution and the impact on mortality
Background Elevated temperature and air pollution have been associated with increased mortality. Exposure to heat and air pollution, as well as the density of vulnerable groups varies within cities. The objective was to investigate the extent of neighbourhood differences in mortality risk due to heat and air pollution in a city with a temperate maritime climate. Methods A case-crossover design was used to study associations between heat, air pollution and mortality. Different thermal indicators and air pollutants (PM10, NO2, O3) were reconstructed at high spatial resolution to improve exposure classification. Daily exposures were linked to individual mortality cases over a 15 year period. Results Significant interaction between maximum air temperature (Tamax) and PM10 was observed. During “summer smog” days (Tamax > 25 °C and PM10 > 50 μg/m3), the mortality risk at lag 2 was 7% higher compared to the reference (Tamax 15 °C and PM10 15 μg/m3). Persons above age 85 living alone were at highest risk. Conclusion We found significant synergistic effects of high temperatures and air pollution on mortality. Single living elderly were the most vulnerable group. Due to spatial differences in temperature and air pollution, mortality risks varied substantially between neighbourhoods, with a difference up to 7%
Crystal-field ground state of the non-centrosymmetric superconductor CePt3Si: a combined polarized soft X-ray absorption and polarized neutron study
We determined the crystal-field split Hund's rule ground state of the
non-centrosymmetric heavy fermion superconductor CePt3Si with polarization
dependent soft X-ray absorption spectroscopy (XAS) and polarized neutron
scattering. We are also able to give the sequence of the crystal-field states
from the temperature evolution of the linear dichroic signal in the XAS. The
quantitative analysis of the XAS temperature dependence together with the
neutron transition energies complete the identification of the crystal-field
level scheme.Comment: 6 pages, 5 figures, submitted to PR
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