Geoscience Reference
In-Depth Information
11.6 Spatio-Temporal Epidemiological Modeler (STEM)
The public domain Spatiotemporal Epidemiological Modeler (STEM) tool, initially
released by IBM, is designed to help scientists and public health officials create
and use spatial and temporal models of emerging infectious diseases. These models
could aid in understanding and potentially preventing the spread of such diseases.
Policymakers responsible for creating strategies to contain diseases and prevent epi-
demics need an accurate understanding of disease dynamics and the likely outcomes
of preventive actions. In an increasingly connected world with extremely efficient
global transportation links, the modes of infection can become quite complex.
STEM facilitates the development of advanced mathematical models, the creation
of flexible models involving multiple populations (species) and interactions between
diseases, and a better understanding of epidemiology.
The STEM application has built-in Geographical Information System (GIS) data
for almost every country in the world. It comes with data about country borders,
populations, shared borders (neighbors), interstate highways, state highways, and
airports. These data come from various public sources. STEM is designed to make
it easy for developers and researchers to plug in their own models.
It comes with spatiotemporal Susceptible/Infectious/Recovered (SIR) and
Susceptible/Exposed/Infectious/Recovered (SEIR) models pre-coded with both
deterministic and stochastic engines. The parameters in any model are specified
in XML configuration files. Users can easily change the weight or significance
of various disease vectors (such as the weights of highways, shared borders, air-
ports, etc.). Users can also create their own unique vectors for disease. Further
details are available in the user manual and design documentation. Download
and installation information is provided at the STEM Eclipse Setup webpage
(
http://wiki.eclipse.org/index.php/STEM_Eclipse_Setup
). Once STEM is installed
on the computer, a sample scenario gives more information about how diseases are
modeled in STEM (
http://wiki.eclipse.org/Creating_a_STEM_Scenario
).
11.7 Hydrologic Engineering Center River Analysis System
(HEC-RAS)
Hydrologic Engineering Center River Analysis System (HEC-RAS) is a river
hydraulic tool created by the U.S. Army Corps of Engineers (USACE) in 1994.
HEC-RAS is a next generation (NextGen) hydraulic successor of the HEC-2 water
surface program. The model can be linked to a geographic information system
(GIS), thereby greatly facilitating the prediction and monitoring of flooding through
visual and spatial analysis.
HEC-RAS is a one-dimensional, steady flow, water surface profiling program
(U.S. Army Corps of Engineers
2002
); it is capable of modeling a full network of
channels, a dendritic system, or a single river reach. HEC-RAS requires the input
of geometric data in order to plot water surface profiles for subcritical, critical, and
