K-T


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AcronymDefinition
K-TCretaceous-Tertiary
References in periodicals archive ?
Scientists first raised the idea of K-T impacts in 1979, after finding a thin layer of clay containing high concentrations of the element iridium in 65-million-yearold sediments, Because iridium is much more abundant in comets and asteroids than in Earth's crust, the scientists proposed that the clay layer represents the failout from a thick dust cloud created when an extraterrestrial body walloped Gravity data from Chicxulub show the buried crater.
Like a central piece in a puzzle, the date for Chicxulub pulls together many disparate clues in the K-T mystery.
Many scientists who support the impact theory have estimated that half of all life on Earth went belly up in abrupt extinctions at the K-T boundary.
While speaking at a conference that year, Penfield even proposed this site as a candidate crater to fit the Alvarez group's new theory about the K-T extinctions.
Botanical evidence from eastern Wyoming suggests that around the time of the K-T boundary, lotuses bloomed in late June, Wolfe says, indicating the impact occurred earlier, near the beginning of June.
This kind of geologic fingerprints fits with several structures proposed as the K-T impact site, including a round feature on the northern end of the Yucatan peninsula, identified last year as a leading candidate (SN: 11/17/90, p.319).
The K-T clay layer in Haiti is also unusually thick -- about 25 times the size of any other such deposit.
Since the discovery of the iridium layer at Gubbio, scientists have found the element at more than 100 K-T boundary sites worldwide.
They found the molecules tens of centimeters above and below the clay layer that marks the K-T boundary in Denmark.
In the past, scientists studying the K-T boundary have found only hints of this mineral.
For k-t BLAST/SENSE and k-t GRAPPA with the residual k-space method, in which the temporal invariant terms were calculated separately and subtracted from each frame before reconstruction, artificial sparsity was also successfully developed for dMRI applications [5, 6].
The k-t FOCUSS is a successful method, which imposes a sparsity constraint in the temporal transform domain by using the FOCUSS algorithm [9], and extends the FOCUSS technique with motion estimation and compensation to compressed sensing framework for cardiac cine MRI.