Various accessibility activities are improving blind access to the increasingly indispensable WWW. These approaches use various metrics to measure the Web's accessibility. “Ease of navigation” (navigability) is one of the crucial factors for blind usability, especially for complicated webpages used in portals and online shopping sites. However, it is difficult for automatic checking tools to evaluate the navigation capabilities even for a single webpage. Navigability issues for complete Web applications are still far beyond their capabilities. This study aims at obtaining quantitative results about the current accessibility status of real world Web applications, and analyzes real users' behavior on such websites. In Study 1, an automatic analysis method for webpage navigability is introduced, and then a broad survey using this method for 30 international online shopping sites is described. The next study (Study 2) focuses on a fine-grained analysis of real users' behavior on some of these online shopping sites. We modified a voice browser to record each user's actions and the information presented to that user. We conducted user testing on existing sites with this tool. We also developed an analysis and visualization method for the recorded information. The results showed us that users strongly depend on scanning navigation instead of logical navigation. A landmark-oriented navigation model was proposed based on the results. Finally, we discuss future possibilities for improving navigability, including proposals for voice browsers.

The measurement by IOL Master in a large population of highly myopic patients clearly showed that the axial length continued to increase in a span of 2 years even in the 4th decade of life. The eyes with longer axial length showed a greater increase of axial length, suggesting the possibility that the more myopic eyes become more myopic with increasing age.

Accessibility-related regulations and guidelines are contributing to the steady improvement of Web accessibility. There are various accessibility evaluation tools, and they also help Web authors make their pages compliant with guidelines. As a result, an increasing number of Web pages are compliant with the evaluation tools. These days, however, blind people face the serious problem that reading Web pages is quite difficult. Improvements in information density by using visual effects such as two-dimensional layouts are making it difficult for blind people to understand the page structure. Also, inappropriate alternative texts mislead or confuse blind users.In this paper, to evaluate these kinds of usability problems, we introduce two metrics: navigability and listenability. Navigability evaluates how well structured the Web content is by using headings, intra-page links, labels, etc. Listenability denotes how appropriate the alternative texts are. By using these metrics, we summarize the historical transition of Web usability for blind people.

In this paper, we present a method of QoS mapping between user's preference on video quality and a required bandwidth to transport the video across the network. We first investigate the mapping method from QoS parameters to the required bandwidth on the network. For this purpose, we assume that the underlying network supports some bandwidth allocation mechanism, such as DBR service class in ATM, RSVP, IPv6 and so on. Then, for given QoS parameters in terms of spatial, SNR, and timely resolutions, the required bandwidth to support the MPEG-2 video transmission is determined by analyzing the traced MPEG-2 streams. We next consider the mapping method between QoS parameters and the user's perceived video quality, which is quantified by MOS (Mean Opinion Score) evaluation. Based on the above results, we discuss a systematic method to estimate the required bandwidth to guarantee user's preference on video quality.

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The low incidence of nystagmus transition in patients with apogeotropic nystagmus suggests a difference in pathophysiology between apogeotropic nystagmus and other types of BPPV. Stenosis and filling defect (obturation) of canals on MRI, which would indicate an innate narrowing and/or an otoconial jam of the semicircular canal, may account for the intractability of BPPV.

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