ScienceCache
Vol. 171
May 13, 2004
RESEARCH WITH IMPACT: AUSTRALIA WAS LIKELY SITE OF COLOSSAL WALLOP
Evidence is mounting that 251 million years ago, long before the dinosaurs
dominated the Earth, a meteor the size of Mount Everest smashed into
what is now northern Australia, heaving rock halfway around the globe,
triggering mass volcanic eruptions, and wiping out all but about 10
percent of the species on the planet. The “Great Dying,” as
it's called, was by far the most cataclysmic extinction event in Earth's
history, yet scientists have been unable to finger a culprit as they
have with the dinosaur extinction. A new paper published in Science,
however, claims to identify the crater made by that meteor, and it
builds upon an ongoing body of evidence by researchers at the University
of Rochester and the University of California at Santa Barbara (UCSB)
that points the finger for the Great Dying squarely at the heavens. “This
is very likely the impact site we've been looking for,” says
Robert Poreda, professor of earth and environmental sciences at Rochester.
Many experts have scoffed at the idea of a giant meteor causing the
mass extinction between the Permian and Triassic periods, but Poreda
points out that many also scoffed at the idea that a meteor was responsible
for a later and lesser extinction at the Cretaceous/Tertiary boundary
that marks the end of the dinosaurs. Now, the impact theory is largely
accepted. Simulations of a six-mile wide rock striking the site, known
as Bedout, suggest a crater rim should be visible about 60 miles from
the central dome, and despite the extreme age of the impact site and
the rearrangement of continental plates since then, there is evidence
of a rim at that distance. Coincidentally, the Bedout crater, at 120
miles across, is almost exactly the same size as the Chicxulub crater
in the Caribbean that has been identified as the impact site of the
meteorite that dealt the dinosaurs their death blow.
Full story
DAD’S DEATH HELPS NATIONAL EXPERT EVALUATE END-OF-LIFE
CARE
End-of-life options for seriously ill patients have improved considerably,
but still have a ways ago, says a national expert who drew upon the recent
experience of his father’s death to take stock of the status of
end-of-life care in the United States. Physician Timothy Quill was asked
by the New England Journal of Medicine to provide an update on developments
in the field since 1991, when he wrote an article for NEJM detailing
his role in the death of a terminally ill patient. Quill turned to his
own father’s recent death in September 2003 to help illustrate
the good and the bad in end-of-life care, in a piece in today’s
issue of NEJM. In the months leading up to the death of his father, Joseph
Quill, the family experienced several improvements in end-of-life care
from what Timothy Quill witnessed in 1991. These included greater availability
of palliative care, to keep the patient as comfortable as possible while
simultaneously treating the underlying disease; flexibility for admission
into a hospice program; and more “last-resort” options to
ease the suffering of very ill patients. “All the elements of good
end-of-life care are known right now, but what’s not there is any
kind of consistent availability,” says Quill, who is professor
of medicine, psychiatry, and medical humanities and the head of the University’s
Program for Biopsychosocial Studies.
Full story
PREDICTING WHICH SHINGLES PATIENTS WILL HAVE PAIN LONG AFTER RASH HEALS
Older age and severe acute pain are two indicators that put shingles
patients at risk of developing persistent pain after the shingles rash
heals, according to a study led by Robert Dworkin, director of the Anesthesiology
Clinical Research Center, that appeared in last week’s issue of
the journal Neurology. Having symptoms before the rash appeared, the
extent of the rash, and being female are also significant risk factors
for developing pain that persists at least four months beyond the onset
of the rash. Approximately one out of every four or five shingles patients
develops such long-term pain, known as postherpetic neuralgia or PHN. “In
future research, it will be important to examine whether additional risk
factors, such as sensory thresholds or psychological distress, and various
methods of weighting risk factors can increase the accuracy of this prediction,” says
Dworkin. Shingles affects about half a million Americans annually and
is a reactivation of the virus responsible for chicken pox.
Full story
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