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Technical Corner

Exponents

A word about how we represent numbers containing exponents. Owing to the limitations of many present Web browsers, we have chosen not to encode exponents, at least at this stage. Instead we have elected to use the symbol ^ to indicate "ten raised to the power of." For example, 5^3 means 5 multiplied by 10 raised to the power of 3, or 5 times 1000 (which equals 5000). Likewise, 5^-3 means 5 times 10 raised to minus 3, or 5 multiplied by 1/1000, which equals 0.005.

Many numbers with exponents appear in the Cosmos in a Computer exhibit, for example in these documents:

"In the Beginning"

"To the Fourth Power"

Images

In-lined images are numerous within the Expo and may cause slower than satisfactory loading times for people with slower connections. If you are concerned about this, we suggest you turn off automatic-image-loading on your browser. In many instances we provide text alternatives for the inlined images featured, as well as text links for all available material. However, if not viewing the exhibit with a modem, let your broswer "auto-load" image in order to gain the most from the exbibits. Some of the in-lined images and most of the linked images are in JPEG format, so if you are having trouble viewing them, make sure you are using a browser that can handle JPEGs - see below for details.

Movies and Sounds

All movies and sounds were created on the desktop using an Apple Macintosh Quadra 840 AV, in conjunction with Radius VideoVision Studio (v.2.0) hardware and software for digitizing and Adobe Premiere (v.4.0.1) for processing and editing the clips.

Video (160x120 pixels; 15 f.p.s.) and audio (22 KHz; 16 bit) were digitized from betacam SP or 3/4 inch SP tape. QuickTime movies were outputted (Video: 160 x 120 pixels; 15 f.p.s. Audio: 22.05 KHz; 16 bit.) using the Apple Video codec (medium-high quality), then "flattened" before uploading to the server. AIFF sound clips were generated from the QuickTime movies using Premiere's intrinsic capabilities. Unflattened, QuickTime movies were converted into MPEG clips with Sparkle (v.2.02).

Whether downloading movies or soundfiles, the main thing to remember is to "be patient". Filesizes range from under 500K (kilobytes) to more than 10 megabytes (MB). Estimated file sizes are indicated in text underneath all of the movie buttons in order to help you decide whether or not you would like to download a movie or soundfile. Below we've provided estimated download times for each of the three major computing platforms: X/Unix, Macintosh and PC. However, please bear in mind that these estimates were obtained using a direct ethernet (1-10 megabits/second) connection to the Internet. Download times could be considerably longer if the bandwidth of your connection is smaller.

In some exciting new developments, QuickTime and MPEG movies can now be streamed, allowing the movies to be played before all the data has been sent, thus greatly decreasing your waiting time for downloading. Currently, several of the Expo movies are in streamed QuickTime format. See the appropraite platform sections below to find out more about what you need to view them. Especially with emerging standardized technology from Netscape, streaming of QuickTime movies should become a more standard cross-platform alternative in the very near future.

As much as we've tried to make the exhibit accessible to all of our viewers, fact is that 14.4K and even faster modems cannot handle the amount of data required in "reasonable" amounts of time. For instance, it would take 129 minutes to download the introductory movie with a 14.4K modem.

As an alternative, we have provided a series of still frames or "thumbnails" for each scientific movie. You can view the thumbnails by simply clicking on the center image in the movie window. This feature is not available for on-camera videobytes because the picture doesn't change much. In this case, it might be informative to look at the or text. A text caption is is available for some of the scientific movies -- if you are interested in learning more about what the movie shows.

Connectivity Suggestions: A Summary

If you have an ethernet connection:

If you have a slow ethernet connection or ISDN:

If you have a 14.4K modem:

Technical Information According to Platform

Any problems? Report these via the Technical Scorecard in our comments page, or simply send mail to kmackie@ncsa.uiuc.edu

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Copyright 1995, The Board of Trustees of the University of Illinois


NCSA, 11/18/95. kmackie@ncsa.uiuc.edu