How to use Hermes Viewer

Choosing data to view

To choose a record (and, optionally, a set of annotations) to view, click on the Record Selection tab to make it active. Select a database first. Hermes then shows menus of records and annotators available within that database.

Verify your choices by looking at the Selected values shown above each drop-down menu, and click on Load Record if satisfied. After doing this, the Waveform Viewer tab becomes active.

To look at a different record or set of annotations, click again on the Record Selection tab. To view data from a different database, click on Select New Database to refresh the Record and Annotator menus.

Moving through a record

Waveforms from the chosen record are drawn over a grid with intervals of 0.2 seconds and 0.5 mV. If a set of annotations was chosen, these appear along the bottom edge of the plot.

Controls for moving through the record are below the waveforms; move your mouse pointer over them to view their functions, which are shown as "tooltips".

• To view the record as a movie, simply click (Play Waveform as movie). Click (Pause waveform) to interrupt playback, and 'Play' again to resume the movie. The 'Adjust Speed' slider to control the playback rate (network delays may limit your speed, however).
• You can also navigate using the 'Next' and 'Previous' buttons. Four such buttons allow you to move by half or all of the width of the window, forward or back, and two more allow you to search through the record for the next or previous occurrence of an annotation (which you may choose from the drop-down list between the search buttons).
• There is also a time line representing the entire record, just below the waveform plot. Drag the time line's pointer to any desired location in the record.

Use 'Reset' to move to the beginning of the record and re-initialize the zoom and speed slider controls to their default postitions.

Signal Visibility

It can be difficult to understand a view of many signals. When viewing a record with multiple signals, you may right-click over the waveform plot to obtain a popup menu of the available signals appears. Click on any of these signals to hide them or to make them reappear. (This feature is unavailable in "movie" mode.)

Saving Waveform Plots

Even if your system offers a way to record screenshots (not available on all platforms), a better way to save your output is to get a high-resolution PostScript plot by email. Erase the words "ENTER YOUR ADDRESS" and type your email address in the box, then click on 'Email To:'. Your plot is made with better than screen resolution on the PhysioNet server and sent to you immediately by email.

Note that applet windows are not printed by web browsers, so you cannot use your browser's Print option to record Hermes output.

About Hermes

Hermes is intended to provide an easy and intuitive mechanism to serve users as a web-based portal for viewing incoming data and/or analysis results retrospectively and in real-time. Hermes Viewer is a simplified version of Hermes customized for PhysioNet.

Hermes was designed and implemented by Matt Oefinger (System for remote multichannel real-time monitoring of mouse ECG via the Internet, S.M. thesis, MIT EECS, 2003). Matt's implementation, which includes many additional capabilities, was adapted for PhysioNet by Ali Saeed. George Moody has provided further minor revisions.

Matt writes: "Members of MIT's LCP and Biology Department were instrumental in providing user requirements, test feedback and architectural considerations that were incorporated into the original design. Specifically Roger Mark, George Moody, Wei Zong, Thomas Heldt, Ali Saeed and Monty Krieger, all from MIT, provided an exceptional and knowledgeable core of insight and experience that helped propel development. Similarly in later stages of development Nic Chronos and Fernando Tondato, both of the American Cardiovascular Research Institute in Atlanta, provided exceptional user feedback and suggestions for further development of Hermes into a cardiovascular toxicity screening tool."

Matt's project included not only the original Hermes software, with substantially greater functionality, but also the design and construction of networked data-logging hardware, built using a combination of standard and custom components. Matt writes, with reference to both the hardware and the software: "Nic Chronos in particular devoted substantial time, effort, and financial resources toward building Hermes into a tool that could be considered the beginnings of a marketable product. The development of Hermes as a commercial product would not have been possible without Doug Pierce, who applied his extensive experience in technology commercialization to help Oefinger Enterprises, Inc. to transition Hermes from academia into a licensed technology product. He has continued to provide substantial devotion of time, money and effort toward building business logic to complement and otherwise raw technology."