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This study was designed to evaluate whether subjects with amyloid beta (Aβ) pathology, detected using florbetapir positron emission tomorgraphy (PET), demonstrated greater cognitive decline than subjects without Aβ pathology. Sixty-nine cognitively normal (CN) controls, 52 with recently diagnosed mild cognitive impairment (MCI) and 31 with probable Alzheimer's disease (AD) dementia were included in the study. PET images obtained in these subjects were visually rated as positive (Aβ+) or negative (Aβ-), blind to diagnosis. Fourteen percent (10/69) of CN, 37% (19/52) of MCI and 68% (21/31) of AD were Aβ+. The primary outcome was change in ADAS-Cog score in MCI subjects after 36 months; however, additional outcomes included change on measures of cognition, function and diagnostic status. Aβ+ MCI subjects demonstrated greater worsening compared with Aβ- subjects on the ADAS-Cog over 36 months (5.66 ± 1.47 vs -0.71 ± 1.09, P = 0.0014) as well as on the mini-mental state exam (MMSE), digit symbol substitution (DSS) test, and a verbal fluency test (P0.05). Similar to MCI subjects, Aβ+ CN subjects showed greater decline on the ADAS-Cog, digit-symbol-substitution test and verbal fluency (P0.05), whereas Aβ+ AD patients showed greater declines in verbal fluency and the MMSE (P0.05). Aβ+ subjects in all diagnostic groups also showed greater decline on the CDR-SB (P0.04), a global clinical assessment. Aβ+ subjects did not show significantly greater declines on the ADCS-ADL or Wechsler Memory Scale. Overall, these findings suggest that in CN, MCI and AD subjects, florbetapir PET Aβ+ subjects show greater cognitive and global deterioration over a 3-year follow-up than Aβ- subjects do.

Within several years of establishment of the CIE's Standard Observer, Neugebauer based upon it a device-independent interpretation of ink mixture in halftone color reproduction. Despite limitations of the model, his approach is of fundamental importance at a time in which document preparation in distributed computing environments is coming of age. Fruition of this technology demands a device independent or colorimetric method for representing and rendering color. A commercial, digital system for implementing such an approach (Kodak Designmaster® 8000) has been described and will be reviewed here with particular regard to the output of color imagery on four-color printers. Inversion of Neugebauer's model for conversion of color to device specific signals must be constrained by the color gamut of the output medium and the utilization of the black printer (Gray Component Replacement). The interaction of the black printer with the device gamut and its effect on image quality and metamerism will receive detailed consideration. It will be shown that colorimetry is a powerful tool in maintaining accurate color reproduction during substitution of black for chromatic components, but that properties of the colorants must also be considered in order to realize commercially acceptable GCR. Section 7 of the paper is an enumeration of summary conclusions.

NEURONES which respond preferentially to slits of light of a given orientation have been found at the ganglion cell level of the retina1, as well as at higher centres of the visual system2–4. Present knowledge about the morphology of such cells and the organisation of the inputs to these cells does not account for the origins of their specialised receptive field properties. We report here that the horizontal cells impaled in the visual streak of the turtle retina (a specialised linear area centralis5 analogous to the fovea of higher vertebrates) respond preferentially to slits of light oriented parallel to the streak and thus parallel to the horizontal meridian of the animal's visual field5. Anatomical studies demonstrate that these horizontal cells are all elongated and oriented in the direction of the streak. Thus, our findings show that a class of neurones exists in the retina whose morphologies may form the basis for their specialised receptive field properties.