University of Cincinnati (UC) neuroradiologists believe a brain imaging approach that combines standard magnetic resonance imaging (MRI) scans with specialized contrast-enhanced techniques could lead to more effective diagnoses in patients with difficult-to-detect blood clots in veins of the brain.
James Leach, MD, reports these findings in the April issue of the American Journal of Neuroradiology. This is the first study to correlate the clinical importance of data gleaned from standard MRI scans and detailed contrast-enhanced imaging techniques in patients with chronic thrombosis (blood clots) in veins of the brain.
"Detailed contrast-enhanced techniques produce more defined distinctions between abnormal and normal veins in the membrane around the brain," explains Leach, a neuroradiologist and associate professor at UC and principal investigator of the study. "Evaluating patients using a combination of imaging tools could give us a better understanding of the disease process."
Science & Technology
sing a quartet of space observatories, University of Maryland astronomers may have cracked a 45-year mystery surrounding two ghostly spiral arms in the galaxy M106.
The Maryland team, led by Yuxuan Yang, took advantage of the unique capabilities of NASA's Chandra X-ray Observatory, NASA's Spitzer Space Telescope, the European Space Agency's XMM-Newton X-ray observatory, and data obtained almost a decade ago with NASA's Hubble Space Telescope.
M106 (also known as NGC 4258) is a stately spiral galaxy 23.5 million light-years away in the constellation Canes Venatici. In visible-light images, two prominent arms emanate from the bright nucleus and spiral outward. These arms are dominated by young, bright stars, which light up the gas within the arms. "But in radio and X-ray images, two additional spiral arms dominate the picture, appearing as ghostly apparitions between the main arms," says team member Andrew Wilson of the University of Maryland. These so-called "anomalous arms" consist mostly of gas.
The Maryland team, led by Yuxuan Yang, took advantage of the unique capabilities of NASA's Chandra X-ray Observatory, NASA's Spitzer Space Telescope, the European Space Agency's XMM-Newton X-ray observatory, and data obtained almost a decade ago with NASA's Hubble Space Telescope.
M106 (also known as NGC 4258) is a stately spiral galaxy 23.5 million light-years away in the constellation Canes Venatici. In visible-light images, two prominent arms emanate from the bright nucleus and spiral outward. These arms are dominated by young, bright stars, which light up the gas within the arms. "But in radio and X-ray images, two additional spiral arms dominate the picture, appearing as ghostly apparitions between the main arms," says team member Andrew Wilson of the University of Maryland. These so-called "anomalous arms" consist mostly of gas.
The Hahn-Meitner Institute in Berlin has contracted with the National High Magnetic Field Laboratory and Florida State University to build an $8.7-million hybrid magnet for "neutron scattering" experiments.
As any experienced angler will know, some knots are better than others -- but exactly why a "blood knot" should be stronger than, say, a "reef knot" is far from clear. Now, physicists in Japan have tried to unravel this mystery by carrying out the first experiments into how fishing lines with knots in them actually break. Surprisingly, it turns out that some knots that are strong when made using traditional nylon fishing line are in fact the weakest when made in a more modern material called PVDF
Determining exactly where a knot breaks in a material is not easy. First, the shape of the knot changes as it is tightened. Second, it is difficult to watch how the broken strands recoil, which takes place very quickly. Third, most knots unravel after breaking, making it hard to reconstruct a broken knot.
Determining exactly where a knot breaks in a material is not easy. First, the shape of the knot changes as it is tightened. Second, it is difficult to watch how the broken strands recoil, which takes place very quickly. Third, most knots unravel after breaking, making it hard to reconstruct a broken knot.
Sandstone and granite are very different types of rock, so it might come as a surprise that both materials appear to crack in the same way -- at least according to physicists in Canada and Germany who have measured the sounds given off by rocks before they shatter. What's even more curious is that sounds from the small samples of rock studied by the group have similar characteristics as those detected after an earthquake, suggesting cracking is a universal process that occurs in many different materials over a wide range of size and time scales
Humans have been cracking rocks for at least one million years - first to make tools and then to quarry and shape building materials. While both stone-age toolmakers and modern-day mechanical engineers have developed a practical understanding of the cracking process, a microscopic theory of cracking has remained elusive. The problem is that most rocks are made of grains that come in many different shapes and are arranged in many different ways. This makes it very difficult to predict when and where a crack will begin and how it will propagate.
Humans have been cracking rocks for at least one million years - first to make tools and then to quarry and shape building materials. While both stone-age toolmakers and modern-day mechanical engineers have developed a practical understanding of the cracking process, a microscopic theory of cracking has remained elusive. The problem is that most rocks are made of grains that come in many different shapes and are arranged in many different ways. This makes it very difficult to predict when and where a crack will begin and how it will propagate.
NASA officials say the space agency is capable of finding nearly all the asteroids that might pose a devastating hit to Earth, but there isn't enough money to pay for the task so it won't get done.
The cost to find at least 90 percent of the 20,000 potentially hazardous asteroids and comets by 2020 would be about $1 billion, according to a report NASA will release later this week. The report was previewed Monday at a Planetary Defense Conference in Washington.
Congress in 2005 asked NASA to come up with a plan to track most killer asteroids and propose how to deflect the potentially catastrophic ones.
The cost to find at least 90 percent of the 20,000 potentially hazardous asteroids and comets by 2020 would be about $1 billion, according to a report NASA will release later this week. The report was previewed Monday at a Planetary Defense Conference in Washington.
Congress in 2005 asked NASA to come up with a plan to track most killer asteroids and propose how to deflect the potentially catastrophic ones.
To David Morrison, a senior scientist at NASA, the Earth orbits the sun in a sort of cosmic shooting gallery. More than 1 million asteroids spin around the sun, and it is Morrison's job to figure out which of these bodies of rock, dust and metal could come crashing down on Earth.
Right now, NASA is tracking 127 asteroids that have a very small chance of striking the planet. That number is about to get a lot higher. Stronger telescopes, and a new mandate from Congress, will allow scientists to detect thousands of smaller asteroids more likely to hit Earth. And scientists are plotting ways to stop them, from "gravity tractors" to solar ray guns.
Right now, NASA is tracking 127 asteroids that have a very small chance of striking the planet. That number is about to get a lot higher. Stronger telescopes, and a new mandate from Congress, will allow scientists to detect thousands of smaller asteroids more likely to hit Earth. And scientists are plotting ways to stop them, from "gravity tractors" to solar ray guns.
An underwater survey off San Diego has revealed geological details of how sand builds up along Southern California's continental shelf and could help resource managers to locate deposits to rebuild beaches, according to a report by scientists at Scripps Institution of Oceanography at UC San Diego.
The newly acquired data show the depth of sand levels along 10 kilometers (6.2 miles) of shoreline from La Jolla Cove north to Torrey Pines State Beach and how the sediments are distributed on the shallow, gently sloping seabed adjacent to the shoreline.
The scientists also identified an area of the seafloor uplifted offshore of Torrey Pines State Park that results from a jog in the Rose Canyon fault, similar to the uplift that created Mount Soledad. This uplifted area appears to play a major role in the accumulation of sand in the area, according to Leah Hogarth, a Scripps graduate student and lead author of the article in the journal Geology of the Geological Society of America.
The newly acquired data show the depth of sand levels along 10 kilometers (6.2 miles) of shoreline from La Jolla Cove north to Torrey Pines State Beach and how the sediments are distributed on the shallow, gently sloping seabed adjacent to the shoreline.
The scientists also identified an area of the seafloor uplifted offshore of Torrey Pines State Park that results from a jog in the Rose Canyon fault, similar to the uplift that created Mount Soledad. This uplifted area appears to play a major role in the accumulation of sand in the area, according to Leah Hogarth, a Scripps graduate student and lead author of the article in the journal Geology of the Geological Society of America.
Livermore researchers have moved one step closer to being able to turn on and off the decay of a nuclear isomer.
The protons and neutrons in a nucleus can be arranged in many ways. The arrangement with the lowest energy is called the ground state and all others are called excited states. (This is analogous to the ground and excited states of electrons in an atom except that nuclear excited states are typically thousands of times higher in energy.) Excited nuclear states eventually decay to the ground state via gamma emission or to another nucleus via particle emission. Most excited states are short-lived (e.g., billionth of a second). However, a few are long-lived (e.g., hours) and are called isomers.
Turning the decay on and off is key to using isiomers as high-energy density storage systems such as batteries.
Researchers at Livermore studied an isomer of Thorium-229. This isomer is unique in that its excitation energy is near optical energies, implying that one day scientists may be able to transition Th229 nuclei between the ground and isomeric states using a table-top laser.
"This would then be the first time human control would be exerted over nuclear levels," said Peter Beiersdorfer, an LLNL physicist and co-author of a paper that appears in the April 6 issue of Physical Review Letters. "This only works if the laser is tuned to exactly the correct energy."
The protons and neutrons in a nucleus can be arranged in many ways. The arrangement with the lowest energy is called the ground state and all others are called excited states. (This is analogous to the ground and excited states of electrons in an atom except that nuclear excited states are typically thousands of times higher in energy.) Excited nuclear states eventually decay to the ground state via gamma emission or to another nucleus via particle emission. Most excited states are short-lived (e.g., billionth of a second). However, a few are long-lived (e.g., hours) and are called isomers.
Turning the decay on and off is key to using isiomers as high-energy density storage systems such as batteries.
Researchers at Livermore studied an isomer of Thorium-229. This isomer is unique in that its excitation energy is near optical energies, implying that one day scientists may be able to transition Th229 nuclei between the ground and isomeric states using a table-top laser.
"This would then be the first time human control would be exerted over nuclear levels," said Peter Beiersdorfer, an LLNL physicist and co-author of a paper that appears in the April 6 issue of Physical Review Letters. "This only works if the laser is tuned to exactly the correct energy."
A lifelong obsession leads to the mysterious hedecatope - a seemingly impossible geometric form that, in its own small way, links together the whole universe.
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| ©Computer model courtesy of Carlo Sequin |
| In this 3-D slice of the four-dimensional
hendecatope, colored beams represent the edges of triangles; some triangles are left out for simplicity. |
