منابع مشابه
Impacts, Tillites, and the Breakup of Gondwanaland
Mathematical analysis demonstrates that substantial impact crater deposits should have been produced during the last 2 Gy of Earth's history. Textures of impact deposits are shown to resemble textures of tillites and diamictites of Precambrian and younger ages. The calculated thickness distribution for impact crater deposits produced during 2 Gy is similar to that of tillites and diamictites <2...
متن کاملDid the breakout of laurentia turn gondwanaland inside-out?
Comparative geology suggests that the continents adjacent to northern, western, southern, and eastern Laurentia in the Late Proterozoic were Siberia, Australia-Antarctica, southern Africa, and Amazonia-Baltica, respectively. Late Proterozoic fragmentation of the supercontinent centered on Laurentia would then have been followed by rapid fan-like collapse of the (present) southern continents and...
متن کاملScaling a Given System to a Larger
Scaling the size of parallel systems while maintaining the system performance is an important problem. A default scaling approach by using larger networks to interconnect more processors works only up to a limited extent and the derived conngurations using this approach are not cost-eeective. Recent advents in VLSI and packaging technologies now ooer multiple processors on a single multi-chip m...
متن کاملLarger osteotomies result in larger ostia in external dacryocystorhinostomies.
OBJECTIVE To evaluate whether final ostium size is determined by the osteotomy created during dacryocystorhinostomy (DCR). DESIGN Prospective nonrandomized study. Intraoperative measurements of bony osteotomy were taken during external DCR. Endonasal endoscopy with functional endoscopic dye testing and internal ostium photography were performed 3 months after surgery. RESULTS Fifty patients...
متن کاملWhy do larger mothers produce larger offspring? A test of classic theory.
Across a wide range of taxa, larger mothers produce larger offspring. Theory assumes that larger, more fecund mothers create higher local densities of siblings, and so larger mothers produce larger offspring to offset sibling competition. This assumption has been debated for over 30 yr, but direct empirical tests are surprisingly rare. Here, we test two key assumptions of classic theories that ...
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ژورنال
عنوان ژورنال: Nature
سال: 1974
ISSN: 0028-0836,1476-4687
DOI: 10.1038/250016a0