The remarkably good curve-fitting of our clinical data to the sigmoid curve is additional evidence that a gradual, rather than an abrupt, change in slope describes the compli- ance properties of the ARDS lung. However, usu- ally there is not a true linear segment in the P-V curve, but rather a gradual change from upward concavity to downward, and recruitment may be taking place all along the P-V curve (6,17,22). This has been interpreted as the pressure above which recruitment has been completed (1,21). has been described as the point where compliance suddenly changes to become "straight" or the "knee" of the curve (4, 15). Points of maximum compliance increase or decrease falling outside the range of data col- lected ( 0 cm H 2 O or the highest data point collected in cm H 2 O) were not included in the.
The point of maximum compliance increase (P mci, where the rate of change of upward slope is maximal or where the second derivative of the function has a maximum) is: c -1.317 d (17). Initial guess co- efficients were a 0 L, b 3 L, c 20 cm H 2 O, d 10 cm H 2 O. The algorithm was set to run until the resulting sum of squared residuals changed by 0.0001, yielding estimates of the pa- rameters a, b, c, and d and the best-fit coefficient R 2. Using the program DeltaGraph (SPSS Inc., Chicago, IL), the equation was fitted to the P-V data using the Leven- berg-Marquardt iterative algorithm to minimize the sum of squared residuals. This equation has four fitting parameters: a, in units of volume, representing the lower asymptote b, in units of volume, representing the distance from a to the upper as- ymptote, or inspiratory capacity c, in units of pressure, representing the true inflection point (where concavity changes direction) d, in units of pressure, representing the distance from c of the zone of high compliance ( Figure 1). If you can live with DeltaGraph’s minor annoyances and limitations, most of which Red Rock says it will correct later this year, you’ll reap the reward of an almost unlimited number of ways to get your message across. The charting functions in Microsoft Excel and PowerPoint may be sufficient for simple jobs, but DeltaGraph 5.0.2 offers many more specialized chart formats than either program. You can use DeltaGraph to handle an entire presentation - charts and text - with one application. The results aren’t as stunning as those you can get from dedicated diagramming programs such as The Omni Group’s OmniGraffle, but they’re adequate for many tasks. Double-click on the symbol next to the top-level entry, and DeltaGraph generates a standard organizational chart or a bulleted text list. You enter text into an outliner view that mimics a standard yellow notepad, complete with ruled lines and a red margin.
Deltagraph curvefit pdf#
Apple’s Keynote achieved the best results by converting our charts into PDF files, but we had to use the Save As PDF feature in Keynote’s Print dialog box to do so.ĭeltaGraph also reaches beyond traditional numerical charting by letting you work with text-based hierarchical data.
DeltaGraph supports several export formats, but PDF isn’t one of them.
Still, we suspect that most users will opt to transfer DeltaGraph charts to dedicated presentation applications. Another feature leverages DeltaGraph’s ability to store multiple pages of charts in a single document it lets you display your graphs sequentially in slide-show format.
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