299 research outputs found

    Non-Invasive Bleaching of the Human Lens by Femtosecond Laser Photolysis

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    Background: Globally, cataract is the leading cause of blindness and impaired vision. Cataract surgery is an attractive treatment option but it remains unavailable in sufficient quantity for the vast majority of the world population living in areas without access to specialized health care. Reducing blindness from cataract requires solutions that can be applied outside operating theatres. Cataract is a protein conformational disease characterized by accumulation of light absorbing, fluorescent and scattering protein aggregates. The aim of the study was to investigate whether these compounds were susceptible to photobleaching by a non-invasive procedure and whether this would lead to optical rejuvenation of the lens. Methodology/Principal Findings: Nine human donor lenses were treated with an 800 nm infra-red femtosecond pulsed laser in a treatment zone measuring 16160.52 mm. After laser treatment the age-induced yellow discoloration of the lens was markedly reduced and the transmission of light was increased corresponding to an optical rejuvenation of 3 to 7 years. Conclusions/Significance: The results demonstrate that the age-induced yellowing of the human lens can be bleached by a non-invasive procedure based on femtosecond laser photolysis. Cataract is a disease associated with old age. At the current technological stage, lens aging is delayed but with a treatment covering the entire lens volume complete optical rejuvenation is expected. Thus, femtosecond photolysis has the potential clinical value of replacing invasive cataract surgery by a non-invasive treatment modality that can be placed in mobile units, thus breaking down many of the barriers impedin

    Selfrando: Securing the Tor Browser against De-anonymization Exploits

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    Abstract Tor is a well-known anonymous communication system used by millions of users, including journalists and civil rights activists all over the world. The Tor Browser gives non-technical users an easy way to access the Tor Network. However, many government organizations are actively trying to compromise Tor not only in regions with repressive regimes but also in the free world, as the recent FBI incidents clearly demonstrate. Exploiting software vulnerabilities in general, and browser vulnerabilities in particular, constitutes a clear and present threat to the Tor software. The Tor Browser shares a large part of its attack surface with the Firefox browser. Therefore, Firefox vulnerabilities (even patched ones) are highly valuable to attackers trying to monitor users of the Tor Browser. In this paper, we present selfrando-an enhanced and practical load-time randomization technique for the Tor Browser that defends against exploits, such as the one FBI allegedly used against Tor users. Our solution significantly improves security over standard address space layout randomization (ASLR) techniques currently used by Firefox and other mainstream browsers. Moreover, we collaborated closely with the Tor Project to ensure that selfrando is fully compatible with AddressSanitizer (ASan), a compiler feature to detect memory corruption. ASan is used in a hardened version of Tor Browser for test purposes. The Tor Project decided to include our solution in the hardened releases of the Tor Browser, which is currently undergoing field testing

    Psychometric evaluation of the Questionnaire about the Process of Recovery (QPR)

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    Background: Supporting recovery is the aim of national mental health policy in many countries, including England. There is a need for standardised measures of recovery, to assess policy implementation and inform clinical practice. Only one measure of recovery has been developed in England: the Questionnaire about the Process of Recovery (QPR) which measures recovery from the perspective of adult mental health service users with a psychosis diagnosis. Aims: To independently evaluate the psychometric properties of the 15-item and 22-item versions of QPR. Method: Two samples were used: Dataset 1 (n=88) involved assessment of QPR at baseline, two weeks and three months. Dataset 2 (n=399; ISRCTN02507940) involved assessment of QPR at baseline and one year. Results: For the 15-item version, internal consistency was 0.89, convergent validity was 0.73, test-retest reliability was 0.74 and sensitivity to change was 0.40. Confirmatory factor analysis showed the 15-item version offered a good fit. For the 22 item version comprising two sub-scales, the Interpersonal sub-scale was found to under-perform and the Intrapersonal sub-scale overlaps substantially with the 15 item version. Conclusions: Both the 15-item and the Intrapersonal sub-scale of the 22-item versions of the QPR demonstrated satisfactory psychometric properties. The 15-item version is slightly more robust and also less burdensome, so it can be recommended for use in research and clinical practice. Declaration of interest: None
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