(Logo) About the PPS Web Pages

Index Index

On any page without the "navigation bars", clicking on the small logo (or text, if you have loaded the text-only version of this page) in the top left corner gets you back to the Main Index.

When producing these Web pages the idea has been to avoid using too many fancy images in order to minimize the time it takes to load them. However I thought it was worth including a few in-line images to try make the pages look smart. But see below.

Naturally, with a subject like protein structure, images are an absolutely integral part of the course material, so the above doesnt apply to those pages. Some of the images in the course are quite large (some very) but many of these are "iconized" and we will give an indication of how just how large these are to give you due warning.

Setting your Web-browser so that it ignores images

This is very easily done- for example with Netscape, make sure Auto Load Images (under Options) is not selected. If you are using Mosaic, select Delay Image Loading (under Options). The result is that when any WWW page is loaded, the position of any image is shown (along with its substitute text if provided) without the image itself being displayed.

The Text-only Pages

Having said that, I also considered it worth providing text-only pages, generated automatically. Again, this only applies to the main and sub-index pages of the course hypertree- not to the course material. Here is the text-only version of the Main Index.

WWW Browsers and Cached Files

When you view WWW pages, the browser stores a local copy of the HTML documents and their associated images and other files; i.e. caches them so they don't have to be downloaded from a remote site again the next time you want to access them. The size of these local caches are limited (by options you set on your browser); they therefore generally store the most recently accessed files.

The drawback is that you retain old copies of these cached files- this is a problem when repeatedly accessing a site whose pages are continually being changed- such as the PPS pages.

To overcome this problem, you can force your browser to download a file from its site of origin, instead of using a cached copy- i.e. by pressing the Reload button on Netscape or Mosaic. The course e-mail archives are constantly changing (they are updated every hour at Birkbeck, and every day at the mirror sites), so we recommend that you reload these pages each time you look at them.

Confused caches

You probably have a fixed limit to the disk space you can use and perhaps also to the number of files that you can store on your local system. Its possible for this limit to be reached as a result of files cached by your web-browser, even though the size of the cache itself is less than the amount defined in the options set on the browser. As a result the browser does not report that it can't cache any more files, and it may do strange things such as stubbornly refusing to download the latest version of a file, no matter how many times you press the Reload button. Instead, it carries on displaying an older cached copy. It can be difficult to realize that you are actually in this situation, so this is something to be aware of. The solution is to empty your disk cache (this is under Network Preferences under Options on the latest Netscape), and to ensure you do this periodically before your quota is reached again.

Another problem to be aware of, relating to caches and proxy servers.


Last updated 21st Jan '96