منابع مشابه
A Straight and Narrow Ionized Filament
We report the discovery of a extremely narrow, extremely linear, ionized filament. The filament is ∼ 2.5◦ long and has an Hα surface brightness of ∼0.5 rayleighs. It is at high galactic latitude, stretching from (l, b) = (140.8◦, 39.0◦) to (138.0◦, 37.7◦). The filament is approximately “Y” shaped. The vertical segment of the “Y” is ∼ 1.2◦ long and ∼ 20′′ wide, and the widest separation of the t...
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Neurons in visual cortex are selective for the orientation of a visual stimulus, while the receptive fields of their thalamic input are circular. Cortical orientation selectivity arises from the organization of both thalamic input and local cortical circuits. In this issue of Neuron, Schummers and colleagues provide evidence that the local circuit mechanisms contributing to orientation selectiv...
متن کاملFace-straight-down and face-near-straight-down positions in healthy, prone-sleeping infants.
OBJECTIVE To determine the frequency and physiologic consequences of the face-straight-down (FSD) position, a postulated mechanism for the sudden infant death syndrome in prone-sleeping infants. STUDY DESIGN A survey of 151 infants, aged 1 to 7 months, in Montreal showed that 33% slept prone. Ten healthy prone-sleeping infants were studied in their homes at age 10 to 22 weeks. Infrared video ...
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The past decade has seen a tremendous increase in the number of men treated for hypogonadism with the expectation of symptomatic benefit. However, the long-term cardiovascular safety of testosterone replacement remains unknown because retrospective studies of testosterone replacement have been inconsistent, and definitive, prospective, randomized studies are lacking. The purpose of this review ...
متن کاملThe straight and narrow path: the evolution of straight-line dispersal at a cane toad invasion front.
At the edge of a biological invasion, evolutionary processes (spatial sorting, natural selection) often drive increases in dispersal. Although numerous traits influence an individual's displacement (e.g. speed, stamina), one of the most important is path straightness. A straight (i.e. highly correlated) path strongly enhances overall dispersal rate relative to time and energetic cost. Thus, we ...
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ژورنال
عنوان ژورنال: Nature
سال: 1992
ISSN: 0028-0836,1476-4687
DOI: 10.1038/358195a0