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Location-based information contained in publicly available GIS databases is invaluable for many applications such as disaster response, national infrastructure protection, crime analysis, and numerous others. The information entities of such databases have both spatial and textual descriptions. Likewise, queries issued to the databases also contain spatial(More)
A datatype with increasing importance in GIS is what we call the location history–a record of an entity's location in geographical space over an interval of time. This paper proposes a number of rigorously defined data structures and algorithms for analyzing and generating location histories. Stays are instances where a subject has spent some time at a(More)
STUDY DESIGN Retrospective study. OBJECTIVE To evaluate the clinical and functional outcomes in patients with spinal cord injury (SCI) and preexisting ankylosing spondylitis (AS). SUMMARY OF BACKGROUND DATA AS alters the strength and biomechanical properties of the spine that renders it susceptible to fracture with minimal trauma. Neurologic involvement(More)
Location information gathered from a variety of sources in the form of sensor data, video streams, human observations, and so on, is often imprecise and uncertain and needs to be represented approximately. To represent such uncertain location information, the use of a probabilistic model that captures the imprecise location as a probability density function(More)
Situational awareness (SA) applications monitor the real world and the entities therein to support tasks such as rapid decision-making, reasoning, and analysis. Raw input about unfolding events may arrive from variety of sources in the form of sensor data, video streams, human observations, and so on, from which events of interest are extracted. Location is(More)
Location-based services like reminders, electronic graffiti, and tourist guides normally require a custom, location-sensitive database that must be custom tailored for the application at hand. This deployment cost reduces the initial appeal of such services. However, there is much location-tagged data already available on the Web which can be easily used to(More)
1 Motivation Recent events (WTC attacks, Southeast Asia Tsunamis, Hurricane Katrina, London bombings) have illustrated the need for accurate and timely situational awareness tools in emergency response. Developing effective situational awareness (SA) systems has the potential to radically improve decision support in crises by improving the accuracy and(More)
In this paper, we consider the problem of discovering GIS data sources on the web. Source discovery queries for GIS data are specified using keywords and a region of interest. A source is considered relevant if it contains data that matches the keywords in the specified region. Existing techniques simply rely on textual metadata accompanying such datasets(More)