Discovery of a new population of high-energy gamma-ray sources in the Milky Way

One of the great mysteries of the high-energy gamma-ray sky is the group of approximately 170 unidentified point sources found along the Galactic plane. They are more numerous than all other high-energy gamma-ray sources combined and, despite 20 years of effort, no clear counterparts have been found at other wavelengths. Here we report a new population of such objects. A cluster of approximately 20 faint sources appears north of the Galactic Centre, which is part of a broader class of faint objects at mid-latitudes. In addition, we show in a model-independent way that the mid-latitude sources are distinct from the population of bright unidentified sources along the Galactic plane. The distribution on the sky indicates that the faint mid-latitude sources are associated with the Gould belt of massive stars and gas clouds at approximately 600 light years distance, as has been previously suggested.     

Mutations in MERTK, the human orthologue of the RCS rat retinal dystrophy gene, cause retinitis pigmentosa

Mutation of a receptor tyrosine kinase gene, Mertk, in the Royal College of Surgeons (RCS) rat results in defective phagocytosis of photoreceptor outer segments by the retinal pigment epithelium (RPE) and retinal degeneration. We screened the human orthologue, MERTK, located at 2q14.1 (ref. 10), in 328 DNA samples from individuals with various retinal dystrophies and found three mutations in three individuals with retinitis pigmentosa (RP). Our findings are the first conclusive evidence implicating the RPE phagocytosis pathway in human retinal disease.     

Growth patterns in the developing brain detected by using continuum mechanical tensor maps

The dynamic nature of growth and degenerative disease processes requires the design of sensitive strategies to detect, track and quantify structural change in the brain in its full spatial and temporal complexity. Although volumes of brain substructures are known to change during development, detailed maps of these dynamic growth processes have been unavailable. Here we report the creation of spatially complex, four-dimensional quantitative maps of growth patterns in the developing human brain, detected using a tensor mapping strategy with greater spatial detail and sensitivity than previously obtainable. By repeatedly scanning children (aged 3-15 years) across time spans of up to four years, a rostro-caudal wave of growth was detected at the corpus callosum, a fibre system that relays information between brain hemispheres. Peak growth rates, in fibres innervating association and language cortices, were attenuated after puberty, and contrasted sharply with a severe, spatially localized loss of subcortical grey matter. Conversely, at ages 3-6 years, the fastest growth rates occurred in frontal networks that regulate the planning of new actions. Local rates, profiles, and principal directions of growth were visualized in each individual child.     

Optimal Aminco-Bowman spectrophotofluorometer slit sizes and arrangements for the analysis of serotonin-O.P.T.

Résumé Une sélection des dimensions et des arrangements optimaux des fentes a été étudiée pour l'évaluation du complexe sérotonine-O.P.T. (o-phthaldialdéhyde) au moyen du spectrophotofluorimètre Aminco-Bowman. Les meilleures conditions ont été réalisées avec les dimensions de 5.0, 4.0, 5.0, 5.0, 4.0, 5.0 et 5.0 mm dans les positions 1–7 respectivement.