منابع مشابه
The Crowing Hen: Early Observations on Spontaneous Sex Reversal in Birds *
Occasionally, throughout the centuries, a farmer has seen an old hen gradually assuming masculine behavior and plumage, or a hunter has found that the "cock" pheasant he had shot was really a female. Such unnatural transformations sometimes chilled the observer with terror of evil things to come, or sometimes, more reasonably, stirred a naive or intelligent curiosity. As superstition flourished...
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We examine evidence supporting the associations among physical activity (PA), cognitive vitality, neural functioning, and the moderation of these associations by genetic factors. Prospective epidemiological studies provide evidence for PA to be associated with a modest reduction in relative risk of cognitive decline. An evaluation of the PA-cognition link across the life span provides modest su...
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of a widespread species than to be faced with the challenge of conserving every population because all are distinctive. Undoubtedly, some reptile species have already gone extinct before we even knew they existed. But a lot remain to be discovered: for example, a single square kilometre of Australian desert can contain 14 co-existing species of the lizard genus Ctenotus (many of them so similar...
متن کاملVitality of optical vortices
Optical vortices are always created or annihilated in pairs with opposite topological charges. However, the presence of such a vortex dipole does not directly indicate whether they are associated with a creation or an annihilation event. Here we propose a method to distinguish between vortex dipoles that have just been created and those that are about to be annihilated. We use first and second ...
متن کاملLuminous Phenomena of Earthquakes: Observations and Theories
Over the past few years, different theories (piezoelectric, positive holes, friction-vaporization, exo-electron emission, tribo- or fracture electrification) have been presented for the interpretation of earthquake lights. Although these theories can interpret earthquake luminous, each suffer from particular problems. There are also ambiguities and questions about the location of the light, the...
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ژورنال
عنوان ژورنال: Journal of the American Association of Instructors and Investigators of Poultry Husbandry
سال: 1918
ISSN: 2666-3651
DOI: 10.3382/ps.0050024a