-
Activation Breakpoint
-
Any cell may be designated
(typically a
Microscope Window)
as an activation breakpoint, such that whenever the
cell is activated during a trial,
the trial is immediately discontinued
and control returns to the user or script.
-
AppFun
-
An abbreviation for "application function", this refers to a CESLab scripting function
that is associated with an instance of the CESLab application, and not a particular
Bench.
-
Automatic Cell
-
A cell that self-activates whenever a certain temporal
interval (known as the automatic
period) has elapsed since its last completion of recovery. In biological hearts, most
cells possess
some degree of automaticity, but in CESLab, this characteristic is typically applied
only to SA nodal cells.
-
Automatic Period
-
For automatic cells, the temporal
interval after recovery is complete at which the
cell will spontaneously reactivate
(unless activated earlier by a neighboring cell).
-
Axial Conduction Speed
-
The speed at which a given cell propagates activation in
directions parallel to the fiber orientation at that cell
(if any).
-
Bench
-
A Bench is comprised of the preparation
and the
instruments through which the user interacts with the
preparation.
Each Bench is associated with a particular Macintosh file, and may
opened/launched, renamed, copied, modified, and saved just like any other
Macintosh document file.
-
BenchFun
-
An abbreviation for "Bench function", this refers to a scripting function that is
associated with a particular Bench,
as opposed to application functions.
-
Bench Script
-
A sequence of ESL
statements that may be edited/executed as a unit. Each Bench Script is
associated with a particular Bench,
and is saved on disk when the Bench is saved.
-
Border
-
The boundaries that delimit simple shapes in the CESLab shape
modeling subsystem.
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Cell
-
In CESLab, the term "cell" refers not to microscopic biological cells, but to the small cubes
(finite elements) which together comprise the modelled heart. Each CESLab cell thus
represents a small group of biological cells, and captures their behavior and interactions
with other simulated cells.
-
Cell Neighborhood
-
The rule that establishes to which nearby cells a given
cell
may directly propagate activation. For reasons of computability and symmetry,
finite element excitable network models such as CESLab that
employs cubic cells usually set the neighborhood size at
either 18 (cells contacting at sides and edges)
or 26 (cells contacting at sides, edges, and corners).
-
Cell Set
-
Within any preparation,
cells are divided up into one or more distinct cell sets.
Each possesses
its own Cartesian coordinate system and cell size,
and can communicate
excitation with other cell sets via junctions.
Cell Set Viewer windows may be used to examine/modify particular cell sets.
-
Cell Size
-
The length of an edge of a cubic cell.
All cells
within a given cell set have the same size.
-
Color Key
-
A small retangular area within certain CESLab instrument
windows that displays placards of
different colors, each accompanied by an explanatory legend, that associate names or numeric
values with the displayed data.
-
Compound Shape
-
A set of shapes that share common borders,
used to represent objects with complex nested components (e.g. the geometry
of the heart).
-
Coupling Interval
-
The temporal offset from the beginning of a given trial
at which a given
automatic cell will first spontaneously activate.
-
Current Bench
-
The bench
associated with the frontmost window of the CESLab application. If
the Application Log Window
is the frontmost window, then there is no current Bench.
Note that the current bench persists even if the CESLab application is moved
to the background.
-
Curve
-
A one dimensional entity that represents a connected set of
points in three-space. Curves may be viewed/edited using
Shape Editor windows.
Note that the term "Curve" is also used in its non-geometric mathematical sense to
describe the functional parametric mappings used to define decremental conduction,
interval/duration, and interval/potential effects.
-
Decremental Conduction
-
A phenomenon observed in biological heart cells in which the speed at which activation
is propagated is slowed if the duration since the last activation (and, to some extent,
preceding ones) is shortened. This is generally associated with decreased phase 0 upstroke
velocity.
-
Default Interactivation Interval
-
A temporal value used as the assumed
interactivation interval
for the purposes of computing
relevant electrophysiological characteristics (interval/potential and interval/duration
factors) for the first activation of a given cell
in a given trial. Succeeding
activations employ the actual per-cell
interactivation interval.
-
Dipole Generation Checksum
-
A hexadecimal number computed for each trial
upon automatic termination due to achievement of
electrophysiological statis, representing a unique combination of the current
dipole generated over time throughout the trial.
It is statistically guaranteed (with the likelihood of
error being 1 in 232) that the checksums computed for any
two trials will differ if and only if
the current dipole generated at corresponding instants during the
trials differs to any degree.
Checksums provide a way of uniquely characterizing a particular configuration
of all dipole-related preparation
parameters, enabling the user to prove that two preparations are
functionally equivalent (at least in terms of generated dipole), or
that a preparation
has been successfully brought back to an earlier configuration.
-
Dipole Sampling Interval
-
The temporal interval over which simulated current dipole is permitted to accumulate
in temporary storage before it is delivered to instruments for
display.
In general, smaller dipole sampling intervals yield better results in
instruments
that display dipole or surface potentials, as the data is less granular over time.
However, the time required for execution of a given trial
varies inversely with the
dipole sampling interval.
-
Dipole Source Location (DSL)
-
The location corresponding to the centroid of a
Regional Dipole. This term is typically used to refer to the location in
the torso Cartesian space, after the locations in cell space have been transformed
by the relevant matrix.
-
ElectroWorld
-
The subset of the preparation
composed of the polyhedra, electrodes, and the
Regional Dipoles. It exists solely in the torso Cartesian space.
-
Employment
-
A flag associated with certain types of Preparation objects
(e.g. polyhedra) that indicates whether it is to be
used in simulation trials.
-
ESL
-
An acronym for "Electrophysiological Scripting Language", this is a proprietary
language that is used to define automated scripts under CESLab.
-
Excitable Cell
-
A Cell that is capable of being electrophysiologically activated.
-
Excitation Threshold
-
The electrical potential (Voltage) that must be exceeded by the
Transmembrane Action Potential of a neighboring
Cell in order to trigger activation of a given
Cell.
-
Fiber
-
A subtissue that is represented by a connected
set of cells positioned along a particular curve in three-space.
-
Fractional Depth
-
For most cells associated with
subtissue walls, CESLab is able to assign
a numerical value representing its fractional depth: this is defined to be
zero at the epicardial surface, unity at the endocardial surface; intramural
cells
have their fractional depths assigned by interpolation between these values.
Fractional depths are typically used to compute fiber orientations and
assign repolarization gradients.
-
Frozen Window
-
An instrument window for which the data currently displayed
is to preserved as-is despite any subsequent trial activity.
Display parameters for frozen windows may still be changed,
e.g. to view extant tracings from different axes. Like all accumulated
Instrument data
in CESLab, frozen data is not stored on disk if
the Bench is closed; the window will be unfrozen and without data
when the Bench file is re-opened.
Windows are usually frozen in order to save displayed
data from earlier trials while changes
are made to the preparation. This makes it easy to
perform A/B comparisons
with data from later trials (either between
windows, or within the same window if it is later unfrozen).
-
Heart Dipole
-
The total instantaneous vector
dipole produced by the entire preparation,
equal to the vectorial sum of
the dipole at each DSL. Sometimes referred to
as a Single Moving Dipole vector.
By its nature, the Heart Dipole is independent of the number of
regional dipoles and the torso model.
-
Heart Dipole Graph
-
An instrument
that graphs the axial components of the instantaneous
heart dipole
over time. This is qualitatively similar to an ECG,
but does not involve the torso model or electrodes.
-
Heart Dipole Scope
-
An instrument
that displays the tracing made by the instantaneous
heart dipole
over time in 3-D. This is qualitatively similar to a VCG,
but does not involve the torso model or electrodes.
-
Instrument
-
A window associated with some particular Bench, using which the user may
interact with the Bench's preparation.
-
Interactivation Interval
-
The elapsed time between two activations of a given cell.
-
Interval/Duration Effect
-
A phenomenon observed in biological hearts in which the action duration (the length
of phases 2 and 3) is shorter if the
interactivation interval is decreased.
-
Interval/Potential Effect
-
A phenomenon observed in biological hearts in which the action potential magnitude
(relative to resting potential) decreases when the
interactivation interval is decreased.
-
Intracavitary Polyhedron
-
A polyhedron defined within the simulated heart for the purposes of delimiting the
highly conductive blood masses within the ventricles.
These polyhedra improve the accuracy of the computed SPTC.
-
Intramural Phase 2 Duration Gradient
-
A quantity (measured in seconds per meter) used to determine the
activation and recovery duration of a given cell dependent upon
its depth within the associated subtissue wall.
-
Junction
-
An association between two cells that
permits activation to be propagated from
one to the other though they may reside in different cell sets. Junctions are typically used
to propagate excitation from the atrial myocardium to the His tree, from there to the Purkinje
layers, and from there to the ventricular myocardium.
-
Junctional Delay
-
The temporal interval required for activation to propagate across a
junction.
-
Locus
-
A zero-dimensional geometric entity (point), represented on exactly one
editable slice in a Compound Shape. Loci can
be examined, defined, and moved using Shape Editors.
-
Modulator
-
A simulated drug or electrolyte, for which an instantaneous
preparation-wide serum level may be specified by the user.
At any particular serum level, a Modulator may influence the
behavior of the preparation
in one or more of a fixed set of
Modulator Effect Modalities.
-
Modulator Effect Modality
-
One of a fixed set of ways in which a Modulator
can effect the activation potential
waveform or other characteristics of cells.
A suitable curve can be specified
for any combination of Modulator,
tissue type,
and Modulator Effect Modality.
-
Outward Depth
-
A value associated with each subtissue wall
cell, indicating its distance from the closest endocardial surface.
-
Polyhedron Max Facet Size
-
The maximum length to be used for the size of the facets that make up a
given polyhedron. Smaller values yield higher-quality polyhedra, but with
greater numbers of facets.
-
Preparation
-
A set of subtissues, tissue types,
and cells being modelled under CESLab.
-
Regional Dipole
-
For computability reasons, the dipole output of each cell during
trials is assumed to geometrically originate not
at the center of the cell, but at
the nearest of a restricted set of distinguished cells,
known as regional dipoles. These
regional dipoles accumulate dipole from their surrounding cells,
which is then treated as if
it originated at the center of the regional dipole. The number of regional dipoles is
controlled by the Regional Dipole Exclusion Radius
established for the preparation.
-
Regional Dipole Exclusion Radius
-
A parameter of each preparation, effectively specifying
the minimum distance between any
two regional dipole
centroids computed by CESLab. Lowering the exclusion radius tends to
increase the number of regional dipoles employed for electrophysiological simulation,
increasing simulation accuracy (within limits) at the cost of computational resources
(CPU time and main memory usage).
-
Script File
-
A file containing a series of ESL scripting commands. Script files
are executed by double-clicking on them, which causes them to be executed by the
current bench.
-
Shape
-
A free-form, contiguous region of three-space defined as part of a
Compound Shape. Shapes may be viewed and edited using CESLab
Shape Editor windows.
-
Static Trial
-
An initiated (or continued) trial
may enter a state (particularly if automatic cell
retriggering has been disabled) in which no cells
are going to undergo activation phase
transitions, i.e. all cells are again at
rest. The trial
is then denoted as static,
and is typically automatically terminated by CESLab to return control to the user or script.
-
Subtissue
-
A contiguous set of cells that share certain characteristics.
-
Subtissue Wall
-
A subtissue which is assumed to possess distinct
inside and outside surfaces. A fractional depth is automatically assigned to each subtissue
wall cell by CESLab, which may be used
to assign fiber orientations and establish repolarization gradients.
-
Surface Potential Mapping (SPM)
-
The computation of electrical potentials (Voltage) at each facet of a given polyhedron
(usually the outermost torso polyhedron) during a Trial.
SPM can only be generated for polyhedra for which the
Enable SPM checkbox
has been checked, and may be viewed using a
Polyhedron Editor
in Surface Potential facet display
modality.
-
Surface Potential Transfer Coefficients (SPTC)
-
Vectors that may be multiplied
by instantaneous current dipole vectors to yield
scalar potentials at polyhedral surfaces (usually corresponding to the surfaces of the torso,
lungs, or intracavitary blood
masses). The SPTC are computed as needed using zero or more iterations of the
procedure of Gelernter and Swihart (see the document
CESLab Technical Specifications for more information).
-
Time Segmentation
-
A Bench mode in which initiated
trials will be automatically paused after a fixed amount of
simulated time elapses, at which point control will be returned to the user or script.
-
Tissue Node
-
A Subtissue that is represented by one or more
Cells surrounding a particular Locus.
-
Tissue Type
-
An entity associated with each subtissue that captures various
characteristics that might be shared by multiple subtissues.
-
Transverse Conduction Speed
-
The speed at which a cell is to propagate activation in directions
perpendicular to the fiber orientation at that cell (if any).
-
Trial
-
In CESLab, this term refers to each sequence of simulated time (starting at zero)
in which electrophysiological simulation is conducted in the
preparation.
Trials are started via the menu bar command
Start New Trial. Trials may be paused
and continued in general, though certain major modifications made to a
preparation may render
any current trial uncontinuable, so that a new trial will have to be conducted.
-
Vertical Phase 2 Duration Gradient
-
A quantity (measured in seconds per meter) that is used (in
conjunction with the base action and recovery duration of the
associated subtissue) to compute the exact duration of activation
phase 2 for a given cell dependent on its vertical (Y-axis)
offset from the lowermost point of the subtissue.
2
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