685 research outputs found
Data Warehousing Scenarios for Model Management
Model management is a framework for supporting meta-data related
applications where models and mappings are manipulated as first class objects
using operations such as Match, Merge, ApplyFunction, and Compose. To demonstrate
the approach, we show how to use model management in two scenarios
related to loading data warehouses. The case study illustrates the value of model
management as a methodology for approaching meta-data related problems. It
also helps clarify the required semantics of key operations. These detailed
scenarios provide evidence that generic model management is useful and, very
likely, implementable
Generic Schema Matching with Cupid
Schema matching is a critical step in many applications, such as XML message mapping, data warehouse loading, and schema integration. In this paper, we
investigate algorithms for generic schema matching, outside of any particular data model or application. We first present a taxonomy for past solutions, showing that a rich range of techniques is available. We then propose a new algorithm, Cupid, that discovers mappings between schema elements based on their names, data types, constraints, and schema structure, using a broader set of techniques than past approaches. Some of our innovations are the integrated use of linguistic and structural matching, context-dependent matching of shared types, and a bias toward leaf structure where much of the schema content resides. After describing our algorithm, we present experimental results that compare Cupid to two other schema matching systems
A survey of approaches to automatic schema matching
Schema matching is a basic problem in many database application domains, such as data integration, E-business, data warehousing, and semantic query processing. In current implementations, schema matching is typically performed manually, which has significant limitations. On the other hand, previous research papers have proposed many techniques to achieve a partial automation of the match operation for specific application domains. We present a taxonomy that covers many of these existing approaches, and we describe the approaches in some detail. In particular, we distinguish between schema-level and instance-level, element-level and structure-level, and language-based and constraint-based matchers. Based on our classification we review some previous match implementations thereby indicating which part of the solution space they cover. We intend our taxonomy and review of past work to be useful when comparing different approaches to schema matching, when developing a new match algorithm, and when implementing a schema matching component
e-Social Science and Evidence-Based Policy Assessment : Challenges and Solutions
Peer reviewedPreprin
Allies Already Poised to Comply: How Social Proximity Affects Lactation-at-Work Law Compliance
This study demonstrates how legal compliance may be better achieved when organizations include individuals who will advocate for newly codified rights and related accommodations. To understand compliance with a new law and the rights it confers, this article examines as its case study the Lactation at Work law, which amends the Fair Labor Standards Act to mandate basic provisions for employees to express breast milk at work. In particular, this study interviewed those organizational actors who translate the law into the policies affecting workers\u27 daily lives: supervising mangers and human resources personnel. Those studied in this article were âAllies Already:â friends or relatives of breastfeeding workers, or ones themselves, who held proâbreastfeeding values and understood the complexities of combining lactation and employment. They mobilized within their organization to comply with the law swiftly and fullyâoften even overcomplying. This article demonstrates how heightened compliance, particularly with new laws, may be achieved even without directly affected actors mobilizing their own rights if allies champion needed accommodations
The XMM Cluster Survey: evolution of the velocity dispersionâtemperature relation over half a Hubble time
We measure the evolution of the velocity dispersionâtemperature (ÏvâTX) relation up to z = 1 using a sample of 38 galaxy clusters drawn from the XMM Cluster Survey. This work improves upon previous studies by the use of a homogeneous cluster sample and in terms of the number of high-redshift clusters included. We present here new redshift and velocity dispersion measurements for 12 z > 0.5 clusters observed with the Gemini Multi Object
Spectographs instruments on the Gemini telescopes. Using an orthogonal regression method,we find that the slope of the relation is steeper than that expected if clusters were self-similar, and that the evolution of the normalization is slightly negative, but not significantly different from zero (Ïv âT0.86±0.14E(z)â0.37±0.33). We verify our results by applying our methods to cosmological hydrodynamical simulations. The lack of evolution seen in our data is consistent with simulations that include both feedback and radiative cooling
LSST Science Book, Version 2.0
A survey that can cover the sky in optical bands over wide fields to faint
magnitudes with a fast cadence will enable many of the exciting science
opportunities of the next decade. The Large Synoptic Survey Telescope (LSST)
will have an effective aperture of 6.7 meters and an imaging camera with field
of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over
20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with
fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a
total point-source depth of r~27.5. The LSST Science Book describes the basic
parameters of the LSST hardware, software, and observing plans. The book
discusses educational and outreach opportunities, then goes on to describe a
broad range of science that LSST will revolutionize: mapping the inner and
outer Solar System, stellar populations in the Milky Way and nearby galaxies,
the structure of the Milky Way disk and halo and other objects in the Local
Volume, transient and variable objects both at low and high redshift, and the
properties of normal and active galaxies at low and high redshift. It then
turns to far-field cosmological topics, exploring properties of supernovae to
z~1, strong and weak lensing, the large-scale distribution of galaxies and
baryon oscillations, and how these different probes may be combined to
constrain cosmological models and the physics of dark energy.Comment: 596 pages. Also available at full resolution at
http://www.lsst.org/lsst/sciboo
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