渡辺 隆行

WCAG 2.0 has played an important role on Web accessibility. Evaluation of Web accessibility is carried out to conform to WCAG 2.0. Authors and evaluators consult specific techniques of WCAG 2.0 to achieve Web accessibility. Web accessibility, however, is not techniques issues but a communication problem. W3C/WAI has just started a task force to perform preliminary development of a new version of accessibility guidelines. So, now is a good time to reconsider Web accessibility guidelines which focus on communication problems of users. To have a rationale of requirements for upcoming version of Web accessibility guidelines, the proposed paper tries to draw a holistic view of Web accessibility in terms of communication model, which is derived from semiotics. This model uses triangle relationship, authors (developers), content, and users, of WAI model. Authors have a message they want to present to users. The message is encoded with Web technologies into content. Multi-modal content is decoded by user agents and assistive technologies to send a message as view-ports to users. You must notice that the relation between authors and content is unidirectional. The relation between content and users, however, is bidirectional. Users, who have a goal, interact with content through user agents and assistive technologies in a specific context of use. Based on this model, the following 4 points are discussed: (1) It is possible that users interact with content but it is not possible that users interact with authors, which makes communication difficult. (2) We must pay more attention to users’ goal and context when evaluating Web accessibility. (3) Evaluation guideline which does not focus on WCAG but approach Web accessibility from user side is needed. User-centered evaluation is important. (4) To compensate a lack of communication between authors and users, an intelligent content is needed.

視覚障害者のコンピュータ利用に適した超早口音声の音質を改善することが望まれている.しかし超早口音声の評価のためには,聞き手の慣れの効果の考慮が重要である.本研究では親密度を統制した超早口音声の聴取において(1)実験の途中での親密度条件の変化,(2)親密度に関する教示の有無,の要因が聞き手の課題への慣れに与える影響を検証した.約21モーラ/秒という超早口音声の聴取における了解度と心的負荷に着目した実験から,「慣れによって親密度が高いという自覚が促された場合に,特にトップダウン情報としての心的辞書へのアクセスが促進され,その結果として了解度が高くなり心的負荷が少なくなる」という仮説を支持する結果が得られた.

Audio CAPTCHA systems, which distinguish between software agents and human beings, are especially important for persons with visual disability. The popular approach is based on mixing-based methods (MBM), which use the mixed sounds of target speech and noises. We have proposed a deletion-based method (DBM) which uses the phonemic restoration effects. Our approach can control the difficulty of tasks simply by the masking ratio. In this paper, we propose a design principle of CAPTCHA, according to which the tasks should be designed so that the large difference of performance between the machines and human beings can be provided. We also show the experimental results that support the hypotheses as follows: (1) only using MBM, the degree of task difficulty can not be controlled easily, (2) using DBM, the degree of task difficulty and safeness of CAPTCHA system can be controlled easily.

Audio CAPTCHA systems, which distinguish between software agents and human beings, are especially important for persons with visual disability. The popular approach is based on mixing-based methods (MBM), which use the mixed sounds of target speech and noises. We have proposed a deletion-based method (DBM) which uses the phonemic restoration effects. Our approach can control the difficulty of tasks simply by the masking ratio. According to our design principle of CAPTCHA, the tasks should be designed so that the large difference of performance between the machines and human beings can be provided. In this paper, we show the experimental results that support the hypotheses as follows: (1) only using MBM, the degree of task difficulty can not be controlled easily, (2) using DBM, the degree of task difficulty and safeness of CAPTCHA system can be controlled easily.

Purpose.To evaluate if marking up heading elements of Web sites improves usability and accessibility. Method.Task completion times and questionnaire responses were collected from sighted and blind users for two kinds of Web sites: sites marked up appropriately with heading elements, and sites with the same visual appearance but with no heading elements marked up. The experiment was carried out with user agents that could navigate through heading elements. Results.1 Heading elements improved usability both for sighted and blind users in terms of significantly reduced task completion time and also higher user satisfaction with the structured site. 2 A significant difference in accessibility i.e., if reduction of task completion time is larger for blind users than sighted users was not observed when heading elements were marked up. The lack of significant effect in this case might have been due to blind users making use of the user-agent's navigation functions to find the target information efficiently when the heading elements were not present. Conclusions.A combination of content with heading elements marked up, user agents with functions that utilise structure markup, and users with sufficient knowledge about user agents functionality, improves usability for both sighted and blind users and may improve accessibility for blind users. © 2009 Informa UK Ltd All rights reserved.

A prototype lunch delivery web system for visually impaired was developed based on the analysis of human (a visually impaired who wants to order a lunch) to human (a sighted person who helps the visually impaired to decide lunch by reading aloud lunch menu) dialog. Based on the analysis, a prototype system was developed, which consists of three steps: 1) rough selection, 2) selection of favorites, and 3) final selection. The evaluation of the prototype system is performed by the visually impaired only with synthesized speech and key-board. The results showed that our system is effective and easy to use.

To determine how well user agents conform to UAAG 1.0, capabilities of user agents were investigated with UAAG 1.0 Test Suite. It was found that 20 Priority 1 checkpoints were met by all the user agents, while 12 Priority 1 checkpoints, relating to multimedia control and time-dependent interactions, were failed by all of them. The results showed that two major Japanese user agents did not have enough functions to navigate through the Web, whereas the latest ones did have those functions. These results show that there are user agents which meet many requirements of UAAG 1.0 but Web authors still have to pay attention to the capability of the user agents that are considered to be used to browse their content. © Springer-Verlag 2007.

Capabilities of major Japanese user agents, three screen readers and one voice browser, were investigated with the following test files: W3C UAAG 1.0 Test Suite for HTML 4.01, an accessible PDF file, an accessible Flash file, and test files which test Japanese specific issues. Using the UAAG 1.0 Test Suite, 20 out of 48 Priority 1 checkpoints were met by all user agents, while all of the user agents failed to meet 11 of the checkpoints. Test results of all test files were assigned into three categories: capabilities satisfied by almost all user agents, capabilities not satisfied by any of the user agents, and capabilities that were satisfied by some of the user agents only. The test results indicated that 1) two major Japanese user agents do not have enough functions to navigate through a Web page using the structure information of the content, and 2) none of the user agents have enough functions to control multimedia and time-dependent interactions. These results provide an objective evidence to define the Japanese baseline, a set of technologies that a user agent is assumed to support, which is required in the WCAG 2.0 working draft. Accessibility responsibility between Web content and user agents is also determined by the current survey. Copyright 2006 ACM.

The Internet becomes a fundamental infrastructure of the current life. The fundamental technology must be accessible to anyone; otherwise, there arises a digital-divide between the people who can use these technologies and the people who cannot. We must resolve this problem by some means or many people are isolated from the society. To resolve a part of this problem, the author launched Bilingual Emacspeak Project. This open-source project develops a highly capable bilingual speech synthesis system for Japanese visually impaired computer users. In this paper, based on the experiences of Bilingual Emacspeak Project and other projects that concern well-being activities, the prospect, problems, and important points of resolving a digital-divide by open-source project assisted by the Internet is discussed in detail.

An experiment to search for hypothetical neutralino dark matter using lithium fluoride bolometer array is underway. This bolometer array consists of eight pieces of 21 g LiF bolometers. Fluorine has large sensitivity for axially coupled neutralino compared with other nuclei. We report on the first results from the pilot run in a shallow depth site (15 m w.e.). From the measured energy spectra the exclusion limits for the cross section of the elastic neutralino scattering off protons are evaluated.

An experiment to search for hypothetical particle dark matter using cryogenic thermal detector, or bolometer is ongoing. The bolometer consists of eight pieces of 21 g LiF absorbers and sensitive NTD germanium thermistors attached to them and is installed in the Nokogiriyama underground cell which is a shallow depth site (similar to 15 m w.e.). We report on the results from the first running for about ten days using this arrayed bolometer system together with appropriate shieldings and muon veto counters. From the obtained energy spectra the exclusion limits for the cross section of the elastic neutralino-proton scattering are derived under commonly accepted astrophysical assumptions. The sensitivity for the light neutralino with a mass below 5 GeV is improved by this work. (C) 1999 Published by Elsevier Science B,V. All rights reserved.

Exclusive measurements of neutrino-less double beta decays(0 nu beta beta) of Mo-100 were made by means of ELEGANT V at Kamioka Underground Laboratory. Oto Cosmo Observatory has been constructed for underground laboratory for ELEGANT V and VI for the study of 0 nu beta beta of Mo-100 and Ca-48, search for dark matters and so on.

The performance of a 21-g lithium fluoride bolometer is presented. The background spectrum was measured in the surface laboratory. We derive an exclusion plot for the spin-dependent coupled Weakly Interacting Massive Particles (WIMPs) cross section. © 1998 Elsevier Science B.V.

We developed a bolometer with a 0.5 g CdTe absorber using a high-sensitivity NTD germanium thermistor. An energy resolution of 24 keV (FWHM) is obtained for 0.66 to 1.8 MeV γ-rays. It shows a good linearity of the response in the energy range between 0.66 and 5.5 MeV. The gain is found to be stable for a period of 72 days of continuous operation and relatively insensitive to temperature changes of the refrigerator. The temperature change of the refrigerator for this period is within ± 1 mK. Since this material contains double positron emission (β+β+) nuclides 106Cd, 108Cd and 120Te, a new series of double beta decay experiments may become possible with this new method.

A direct dark matter search experiment is now under preparation at the University of Tokyo. An array of LiF bolometers with a total mass of roughly one kilogram is to be used aiming at a direct detection of spin-dependently interacting supersymmetric neutralinos. A dedicated low-radioactivity dilution refrigerator for the bolometer has been constructed along with a small on-line helium requefier to help the detector operation in the underground laboratory where liquid helium supply is not always available. A long term test operation of a bolometer at the University of Tokyo proved the stability of the detector for more than 45 days. The detector will be installed in the Nokogiri-yama underground laboratory of the Institute for Cosmic Ray Research of the University of Tokyo. The laboratory is 200 m w.e. deep and located about 60 km to the south of Tokyo.

A direct dark matter search experiment is now under preparation at the University of Tokyo. An array of LiF bolometers with a total mass of roughly one kilogram is to be used aiming at a direct detection of spin-dependently interacting supersymmetric neutralinos. A dedicated low-radioactivity dilution refrigerator for the bolometer has been constructed along with a small on-line helium requefier to help the detector operation in the underground laboratory where liquid helium supply is not always available. A long term test operation of a bolometer at the University of Tokyo proved the stability of the detector for more than 45 days. The detector will be installed in the Nokogiri-yama underground laboratory of the Institute for Cosmic Ray Research of the University of Tokyo. The laboratory is 200 m w.e. deep and located about 60 km to the south of Tokyo.

Bolometers are being developed at the University of Tokyo aiming at a search for galactic dark matter. We have succeeded in constructing a small-sized bolometer with 2.8 gram of lithium fluoride crystal with an rms energy resolution of 3.8 ke V for 60-ke V γ rays. Both lithium and fluorine are expected to be suitable for the detection of possible particle dark matter with a spin-dependent interaction like supersymmetric neutralinos. Fabrication of Neutron Transmutation Doped (NTD) germanium is also in progress to make a number of thermistors with uniform sensitivities to be used for multi-module bolometers. When the development of a full-sized detector with a total mass of order one kilogram is completed, we plan to install it in the Kamioka underground laboratory. © 1993 Plenum Publishing Corporation.

A cryogenic thermal detector with a 2.8 g LiF crystal is constructed. A photoelectric peak of 60 keV γ-rays is clearly seen with LiF crystal with an RMS energy resolution of 3.8 keV. LiF is suitable for the detection of possible particle dark matter with a spin-dependent interaction like neutralinos since both Li and F are expected to have high interaction rates with such particles. © 1993.

A large and thin source film with area of S almost-equal-to 10(3) cm2 and thickness of t is similar to 20 mg/cm2 has been fabricated for measuring nuclear rare decays. The uniformity is within 10%, and contaminations of U and Th radioactive isotopes are less than 0.5 ppb. It can be used for studying rare nuclear (beta) decays with decay rates of 10(-20)-10(-23) yr-1.

Double beta (betabeta) decays of Mo-100 and charge nonconserving (CNC) X-ray and gamma-ray transitions in I-127 were studied by means of ELEGANTS V.A finite half-life of T1/2(2nu) = 1.15(-0.20)+0.30 x 10(19)yr(68%CL) for the two neutrino betabeta decay and the lower limit of T1/2(0nu) > 7 x 10(21)yr(68%CL) for the neutrino-less betabeta decay were obtained. This corresponds to the mass limit of m(nu) < 7eV. Lower limits on the mean fives of the CNC inelastic and elastic processes, I-127 + e(K) --> I-127* + nu and I-127 + e(K) --> I-127 + nu were obtained as tau > 5.8 x 10(22)yr and tau > 1.2 . 10(23)yr, respectively. Upper limits on the ratios of the CNC strengths to the charge conserving ones for the weak and electromagnetic processes were obtained as epsilon(W)2 < 3.0 x 10(-30) and epsilon(gamma)2 < 1.5 x 10(-46), respectively.

Double beta (betabeta) decays of Mo-100 and charge nonconserving (CNC) X-ray and gamma-ray transitions in I-127 were studied by means of ELEGANTS V.A finite half-life of T1/2(2nu) = 1.15(-0.20)+0.30 x 10(19)yr(68%CL) for the two neutrino betabeta decay and the lower limit of T1/2(0nu) > 7 x 10(21)yr(68%CL) for the neutrino-less betabeta decay were obtained. This corresponds to the mass limit of m(nu) < 7eV. Lower limits on the mean fives of the CNC inelastic and elastic processes, I-127 + e(K) --> I-127* + nu and I-127 + e(K) --> I-127 + nu were obtained as tau > 5.8 x 10(22)yr and tau > 1.2 . 10(23)yr, respectively. Upper limits on the ratios of the CNC strengths to the charge conserving ones for the weak and electromagnetic processes were obtained as epsilon(W)2 < 3.0 x 10(-30) and epsilon(gamma)2 < 1.5 x 10(-46), respectively.

Double beta (beta-beta) decays of Mo-100 were studied by means of ELEGANTS V. A finite half-life of T1/2(2v) = (1.15(-0.20)+0.30) X 10(19) yr (68% CL) for 2v-beta-beta decay and the most stringent lower limit of T1/2(0v) > 4.7 X 10(21) yr (68% CL) on the half-life for the 0v-beta-beta decay were obtained. The observed T1/2(2v) indicates very severe cancellation of the components of the relevant nuclear matrix element.

The normal double beta decay with two neutrinos (2 nu beta beta ) has been studied for 100Mo in order to study experimentally the 2 nu beta beta nuclear matrix element (M2 nu). A low background spectrometer, ELEGANTS-IV, which consists of eleven Si(Li) beta -detectors and surrounding 4 pi -NaI(Tl) gamma -detectors, has been used for the present experiment. natMo and 94% enriched 100Mo source-disks have been measured simultaneously for 8006 hours. A lower limit for the 2 nu half-life was obtained as 7.9(6.2)*1018 years at the 68(90)% confidence level. The present experiment suggests a finite 2 nu half-life of the order of 1019 years. However, it is necessary to estimate the contribution from contamination in the 100Mo disks by a Monte Carlo calculation.

The normal double beta decay with two neutrinos (2-nu-beta-beta) has been studied for Mo-100 in order to study experimentally the 2-nu-beta-beta nuclear matrix element (M2-nu). A low background spectrometer, ELEGANTS-IV, which consists of eleven Si(Li) beta-detectors and surrounding 4-pi-NaI (Tl) gamma-detectors, has been used for the present experiment. (nat)Mo and 94% enriched Mo-100 source-disks have been measured simultaneously for 8006 hours. A lower limit for the 2-nu half-life was obtained as 7.9(6.2) x 10(18) years at the 68(90) % confidence level. The present experiment suggests a finite 2-nu half-life of the order of 10(19) years. However, it is necessary to estimate the contribution from contamination in the Mo-100 disks by a Monte Carlo calculation.

Double beta (beta-beta) decays of Mo-100 and charge nonconserving excitations of I-127 were studied by means of ELEGANTS V. A finite half-life of T1/2(2-nu) = 1.15(-0.20)+0.30 x 10(19)y (68 % CL) for the two neutrino beta-beta-decay of Mo-100 and the most stringent lower limit of T1/2(0-nu) > 4.7 x 10(21) y (68 % CL) on the half-life for the neutrino-less beta-beta-decay of Mo-100 were obtained. Lower limits on the mean life of the charge nonconserving (CNC) processes I-127 + e(K) --> I-127* + nu leading to the first excited states of I-127 were obtained as tau > 1.1 x 10(23)y by searching for the gamma-decay.

Double beta decays ( beta beta ) from the 76Ge ground state (0+) to the 0+ and 2+ states in 76Se have been studied by means of a 171 cm3 Ge detector surrounded by a 4 pi -geometry NaI detector for 8621 h at the Kamioka underground laboratory. All beta -ray signals from the Ge detector and gamma -ray ones from the NaI detector were recorded on magnetic tape with a list mode, and were used to select candidates of beta beta events from background events. Lower limits on the neutrinoless double beta decays (0 nu beta beta ) are obtained as T 12/0 nu0+ to 0+)&gt 0. 73*1023 year and T12/0 nu(0+ to 2+)&gt 0.57*1023 year at the 68% confidence level (CL). The limit on T12/0 nu(0+ to 0 +) gives an upper limit on the Majorana neutrino mass of (m nu)&lt 1.8-4.7 eV, depending on the matrix elements used. The 0 + to 2+ 0 nu beta beta is due to the right-handed weak current. The present value gives the most stringent limit on the T 12/0 nu(0+ to 2+). The lower limit on the half-life for the 0+ to 0+ 0 nu beta beta process accompanied by the Majoron is T12/0 nu M(0+ to 0+)&gt 2*1020 year. This leads to an upper limit on the coupling strength with the Majoron field as mod (gB) mod &lt (0.7-1.8)*10-3. The lower limit on the half-life for the two-neutrino beta beta is T12/2 nu(0+ to 0 +)&gt 1*1020 year.