505 research outputs found
Semantic Matchmaking as Non-Monotonic Reasoning: A Description Logic Approach
Matchmaking arises when supply and demand meet in an electronic marketplace,
or when agents search for a web service to perform some task, or even when
recruiting agencies match curricula and job profiles. In such open
environments, the objective of a matchmaking process is to discover best
available offers to a given request. We address the problem of matchmaking from
a knowledge representation perspective, with a formalization based on
Description Logics. We devise Concept Abduction and Concept Contraction as
non-monotonic inferences in Description Logics suitable for modeling
matchmaking in a logical framework, and prove some related complexity results.
We also present reasonable algorithms for semantic matchmaking based on the
devised inferences, and prove that they obey to some commonsense properties.
Finally, we report on the implementation of the proposed matchmaking framework,
which has been used both as a mediator in e-marketplaces and for semantic web
services discovery
Gamma-Ray Astronomy around 100 TeV with a large Muon Detector operated at Very High Altitude
Measurements at 100 TeV and above are an important goal for the next
generation of high energy gamma-ray astronomy experiments to solve the still
open problem of the origin of galactic cosmic rays. The most natural
experimental solution to detect very low radiation fluxes is provided by the
Extensive Air Shower (EAS) arrays. They benefit from a close to 90% duty cycle
and a very large field of view (about 2 sr), but the sensitivity is limited by
their angular resolution and their poor cosmic ray background discrimination.
Above 10 TeV the standard technique for rejecting the hadronic background
consists in looking for "muon-poor" showers.
In this paper we discuss the capability of a large muon detector (A=2500 m2)
operated with an EAS array at very high altitude (>4000 m a.s.l.) to detect
gamma-ray fluxes around 100 TeV. Simulation-based estimates of energy ranges
and sensitivities are presented.Comment: 4 pages, proceedings of the 30th ICRC, Merida, Mexico, 200
Structured Knowledge Representation for Image Retrieval
We propose a structured approach to the problem of retrieval of images by
content and present a description logic that has been devised for the semantic
indexing and retrieval of images containing complex objects. As other
approaches do, we start from low-level features extracted with image analysis
to detect and characterize regions in an image. However, in contrast with
feature-based approaches, we provide a syntax to describe segmented regions as
basic objects and complex objects as compositions of basic ones. Then we
introduce a companion extensional semantics for defining reasoning services,
such as retrieval, classification, and subsumption. These services can be used
for both exact and approximate matching, using similarity measures. Using our
logical approach as a formal specification, we implemented a complete
client-server image retrieval system, which allows a user to pose both queries
by sketch and queries by example. A set of experiments has been carried out on
a testbed of images to assess the retrieval capabilities of the system in
comparison with expert users ranking. Results are presented adopting a
well-established measure of quality borrowed from textual information
retrieval
Identification of Showers with Cores Outside the ARGO-YBJ Detector
In any EAS array, the rejection of events with shower cores outside the
detector boundaries is of great importance. A large difference between the true
and the reconstructed shower core positions may lead to a systematic
miscalculation of some shower characteristics. Moreover, an accurate
determination of the shower core position for selected internal events is
important to reconstruct the primary direction using conical fits to the shower
front, improving the detector angular resolution, or to performe an efficient
gamma/hadron discrimination. In this paper we present a procedure able to
identify and reject showers with cores outside the ARGO-YBJ carpet boundaries.
A comparison of the results for gamma and proton induced showers is reported.Comment: 4 pages, to be published in the Proceedings of the 28th International
Cosmic Ray Conference (Tsukuba, Japan 2003
Study of RPC gas mixtures for the ARGO-YBJ experiment
The ARGO-YBJ experiment consists of a RPC carpet to be operated at the
Yangbajing laboratory (Tibet, P.R. China), 4300 m a.s.l., and devoted to the
detection of showers initiated by photon primaries in the energy range 100 GeV
- 20 TeV. The measurement technique, namely the timing on the shower front with
a few tens of particles, requires RPC operation with 1 ns time resolution, low
strip multiplicity, high efficiency and low single counting rate. We have
tested RPCs with many gas mixtures, at sea level, in order to optimize these
parameters. The results of this study are reported.Comment: 6 pages, 3 figures. To be published in Nucl. Instr. Meth. A, talk
given at the "5th International Workshop on RPCs and Related Detectors", Bari
(Italy) 199
Idiopathic sensorineural hearing loss is associated with endothelial dysfunction
Hearing impairment is the most prevalent sensory deficit [1].
Sensorineural hearing loss (SNHL) is the most common type of permanent
hearing loss and it occurswhen there is damage to the inner ear
(cochlea), or to the nerve pathways fromthe inner ear to the brain.Most
of the time, SNHL cannot be medically or surgically corrected.
SNHL can result from genetic, environmental, or combined etiologies
that prevent normal function of hearing, but, despite detailed investigation,
the main cause remains usually unknown. Clinical and experimental
studies have shown that ischemia contributes to several SNHL [2], suchas
sudden sensoneural hearing loss, presbyacusis and noise-induced hearing
loss. All of these SNHL can be related to alteration in blood flow [3].
The aim of the study is finding a relationship between idiopathic
SNHL and endothelial dysfunction
Moregrasp: Restoration of Upper Limb Function in Individuals with High Spinal Cord Injury by Multimodal Neuroprostheses for Interaction in Daily Activities
The aim of the MoreGrasp project is to develop a noninvasive, multimodal user interface including a brain-computer interface (BCI) for intuitive control of a grasp neuroprosthesis to support individuals with high spinal cord injury (SCI) in everyday activities. We describe the current state of the project, including the EEG system, preliminary results of natural movements decoding in people with SCI, the new electrode concept for the grasp neuroprosthesis, the shared control architecture behind the system and the implementation of a user-centered design
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