David Kirkpatrick

September 16, 2010

NASA’s LRO finds diversity in the moon’s past

Here’s a release hot from the inbox. (I’m in light blogging mode for the middle of this week due to multiple projects, so I’m taking the easy way out here. Of course presenting the entire release is standard procedure with this blog anyway, so, um, enjoy!)

The release:

NASA’s LRO Exposes Moon’s Complex, Turbulent Youth

GREENBELT, Md., Sept. 16 /PRNewswire-USNewswire/ — The moon was bombarded by two distinct populations of asteroids or comets in its youth, and its surface is more complex than previously thought, according to new results from NASA’s Lunar Reconnaissance Orbiter (LRO) spacecraft featured in three papers appearing in the Sept. 17 issue of Science.

(Logo: http://photos.prnewswire.com/prnh/20081007/38461LOGO)
(Logo: http://www.newscom.com/cgi-bin/prnh/20081007/38461LOGO)

In the first paper, lead author James Head of Brown University in Providence, R.I., describes results obtained from a detailed global topographic map of the moon created using LRO’s Lunar Orbiter Laser Altimeter (LOLA). “Our new LRO LOLA dataset shows that the older highland impactor population can be clearly distinguished from the younger population in the lunar ‘maria’ — giant impact basins filled with solidified lava flows,” says Head. “The highlands have a greater density of large craters compared to smaller ones, implying that the earlier population of impactors had a proportionally greater number of large fragments than the population that characterized later lunar history.”

Meteorite impacts can radically alter the history of a planet. The moon, Mars, and Mercury all bear scars of ancient craters hundreds or even thousands of miles across. If Earth was subjected to this assault as well — and there’s no reason to assume our planet was spared — these enormous impacts could have disrupted the initial origin of life. Large impacts that occurred later appear to have altered life’s evolution. The approximately 110-mile-diameter, partially buried crater at Chicxulub, in the Yucatan Peninsula of Mexico, is from an impact about 65 million years ago that is now widely believed to have led or contributed to the demise of the dinosaurs and many other life forms.

Scientists trying to reconstruct the meteorite bombardment history of Earth face difficulty because impact craters are eroded by wind and water, or destroyed by the action of plate tectonics, the gradual movement and recycling of the Earth’s crust. However, a rich record of craters is preserved on the moon, because it has only an extremely thin atmosphere — a vacuum better than those typically used for experiments in laboratories on Earth. The moon’s surface has no liquid water and no plate tectonics. The only source of significant erosion is other impacts.

“The moon is thus analogous to a Rosetta stone for understanding the bombardment history of the Earth,” said Head. “Like the Rosetta stone, the lunar record can be used to translate the ‘hieroglyphics’ of the poorly preserved impact record on Earth.”

Even so, previous lunar maps had different resolutions, viewing angles, and lighting conditions, which made it hard to consistently identify and count craters. Head and his team used the LOLA instrument on board LRO to build a map that highlights lunar craters with unprecedented clarity. The instrument sends laser pulses to the lunar surface, measures the time that it takes for them to reflect back to the spacecraft, and then with a very precise knowledge of the orbit of the LRO spacecraft, scientists can convert this information to a detailed topographic map of the moon, according to Head.

Objects hitting the moon can be categorized in different “impactor populations,” where each population has its own set of characteristics. Head also used the LOLA maps to determine the time when the impactor population changed. “Using the crater counts from the different impact basins and examining the populations making up the superposed craters, we can look back in time to discover when this transition in impactor populations occurred. The LRO LOLA impact crater database shows that the transition occurred about the time of the Orientale impact basin, about 3.8 billion years ago. The implication is that this change in populations occurred around the same time as the large impact basins stopped forming, and raises the question of whether or not these factors might be related. The answers to these questions have implications for the earliest history of all the planets in the inner solar system, including Earth,” says Head.

In the other two Science papers, researchers describe how data from the Diviner Lunar Radiometer Experiment instrument on LRO are showing that the geologic processes that forged the lunar surface were complex as well. The data have revealed previously unseen compositional differences in the crustal highlands, and have confirmed the presence of anomalously silica-rich material in five distinct regions.

Every mineral, and therefore every rock, absorbs and emits energy with a unique spectral signature that can be measured to reveal its identity and formation mechanisms. For the first time ever, LRO’s Diviner instrument is providing scientists with global, high-resolution infrared maps of the moon, which are enabling them to make a definitive identification of silicate minerals commonly found within its crust. “Diviner is literally viewing the moon in a whole new light,” says Benjamin Greenhagen of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., lead author of one of the Diviner Science papers.

Lunar geology can be roughly broken down into two categories – the anorthositic highlands, rich in calcium and aluminium, and the basaltic maria, which are abundant in iron and magnesium. Both of these crustal rocks are what’s deemed by geologists as ‘primitive’; that is, they are the direct result of crystallization from lunar mantle material, the partially molten layer beneath the crust.

Diviner’s observations have confirmed that most lunar terrains have spectral signatures consistent with compositions that fall into these two broad categories. However they have also revealed that the lunar highlands may be less homogenous than previously thought.

In a wide range of terrains, Diviner revealed the presence of lunar soils with compositions more sodium rich than that of the typical anorthosite crust. The widespread nature of these soils reveals that there may have been variations in the chemistry and cooling rate of the magma ocean which formed the early lunar crust, or they could be the result of secondary processing of the early lunar crust.

Most impressively, in several locations around the moon, Diviner has detected the presence of highly silicic minerals such as quartz, potassium-rich, and sodium-rich feldspar — minerals that are only ever found in association with highly evolved lithologies (rocks that have undergone extensive magmatic processing).

The detection of silicic minerals at these locations is a significant finding for scientists, as they occur in areas previously shown to exhibit anomalously high abundances of the element thorium, another proxy for highly evolved lithologies.

“The silicic features we’ve found on the moon are fundamentally different from the more typical basaltic mare and anorthositic highlands,” says Timothy Glotch of Stony Brook University in Stony Brook, N.Y., lead author of the second Diviner Science paper. “The fact that we see this composition in multiple geologic settings suggests that there may have been multiple processes producing these rocks.”

One thing not apparent in the data is evidence for pristine lunar mantle material, which previous studies have suggested may be exposed at some places on the lunar surface. Such material, rich in iron and magnesium, would be readily detected by Diviner.

However, even in the South Pole Aitken Basin (SPA), the largest, oldest, and deepest impact crater on the moon — deep enough to have penetrated through the crust and into the mantle — there is no evidence of mantle material.

The implications of this are as yet unknown. Perhaps there are no such exposures of mantle material, or maybe they occur in areas too small for Diviner to detect.

However, it’s likely that if the impact that formed this crater did excavate any mantle material, it has since been mixed with crustal material from later impacts inside and outside SPA. “The new Diviner data will help in selecting the appropriate landing sites for potential future robotic missions to return samples from SPA. We want to use these samples to date the SPA-forming impact and potentially study the lunar mantle, so it’s important to use Diviner data to identify areas with minimal mixing,” says Greenhagen.

The research was funded by NASA’s Exploration Systems Missions Directorate at NASA Headquarters in Washington. LRO was built and is managed by NASA’s Goddard Space Flight Center in Greenbelt, Md. LOLA was built by NASA Goddard. David E. Smith from the Massachusetts Institute of Technology and NASA Goddard is the LOLA principal investigator. The Diviner instrument was built and is managed by NASA’s Jet Propulsion Laboratory in Pasadena, Calif. UCLA is the home institution of Diviner’s principal investigator, David Paige.

For images and more information about LRO, visit:

http://www.nasa.gov/lro

Photo:  http://www.newscom.com/cgi-bin/prnh/20081007/38461LOGO
PRN Photo Desk photodesk@prnewswire.com
http://photos.prnewswire.com/prnh/20081007/38461LOGO
Source: NASA

Web Site:  http://www.nasa.gov/

June 26, 2009

Nanotech v. medical implant infection

Nanotechnology is proving to have many very useful medical applications.

The release from today:

Implant bacteria, beware: Researchers create nano-sized assassins

IMAGE: Erik Taylor is a graduate student in engineering at Brown University.

Click here for more information. 

PROVIDENCE, R.I. [Brown University] — Staphylococcus epidermidis is quite an opportunist. Commonly found on human skin, the bacteria pose little danger. But S. epidermidis is a leading cause of infections in hospitals. From catheters to prosthetics, the bacteria are known to hitch a ride on a range of medical devices implanted into patients.

Inside the body, the bacteria multiply on the implant’s surface and then build a slimy, protective film to shield the colony from antibiotics. According to a study in the journal Clinical Infectious Diseases, up to 2.5 percent of hip and knee implants alone in the United States become infected, affecting thousands of patients, sometimes fatally.

More ominously, there is no effective antidote for infected implants. The only way to get rid of the bacteria is to remove the implant. “There is no [easy] solution,” said Thomas Webster, a biomedical engineer at Brown University.

IMAGE: Thomas Webster is an associate professor in engineering and orthopedics at Brown University.

Click here for more information. 

Now, Webster and Brown graduate student Erik Taylor have created a nano-sized headhunter that zeroes in on the implant, penetrates S. epidermidis‘s defensive wall and kills the bacteria. The finding, published in the International Journal of Nanomedicine, is the first time iron-oxide nanoparticles have been shown to eliminate a bacterial infection on an implanted prosthetic device.

In lab tests, Taylor, the lead author, and Webster, associate professor of engineering and orthopaedics, noted that up to 28 percent of the bacteria on an implant had been eliminated after 48 hours by injecting 10 micrograms of the nanoparticle agents. The same dosage repeated three times over six days destroyed essentially all the bacteria, the experiments showed.

The tests show “there will be a continual killing of the bacteria until the film is gone,” said Webster, who is editor-in-chief of the peer-reviewed journal in which the paper appears.

A surprising added benefit, the scientists learned, is the nanoparticles’ magnetic properties appear to promote natural bone cell growth on the implant’s surface, although this observation needs to be tested further.

IMAGE: Iron-oxide nanoparticles developed at Brown University target an infected prosthesis, penetrate a bacterial film on the implant’s surface and thwart the colony by killing the bacteria. The nanoparticles also are…

Click here for more information. 

To carry out the study, the researchers created iron-oxide particles (they call them “superparamagnetic”) with an average diameter of eight nanometers. They chose iron oxide because the metallic properties mean the particles can be guided by a magnetic field to the implant, while its journey can be tracked using a simple magnetic technique, such as magnetic resonance imaging (MRI). Moreover, previous experiments showed that iron seemed to cause S. epidermidis to die, although researchers are unsure why. (Webster said it may be due to iron overload in the bacteria’s cell.)

Once the nanoparticles arrive at the implant, they begin to penetrate the bacterial shield. The researchers are studying why this happens, but they believe it’s due to magnetic horsepower. In the tests, the researchers positioned a magnet below the implant, producing a strong enough field to force the nanoparticles above to filter through the film and proceed to the implant, Webster explained.

The particles then penetrate the bacterial cells because of their super-small size. A micron-sized particle, a thousand times larger than a nanoparticle, would be too large to penetrate the bacterial cell wall.

 

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The researchers plan to test the iron-oxide nanoparticles on other bacteria and then move on to evaluating the results on implants in animals. The research was funded by the private Hermann Foundation Inc. In addition, Taylor’s tuition and stipend are funded through the National Science Foundation GK-12 program.

October 30, 2008

Do political media endorsements matter?

Filed under: Media, Politics — Tags: , , , , — David Kirkpatrick @ 1:01 am

Maybe according to this Brown University study.

The release:

Endorsement Effects: Are Voters Influenced by Newspaper Picks?

More than 150 newspapers across the country have already endorsed Sen. JohnMcCain or Sen. Barack Obama for president, with more to come in the remaining days before the election. Do these endorsements really matter? In a new paper, economist Brian Knight investigates the effect of endorsements on voter decision making and finds that they are, in fact, influential.

PROVIDENCE, R.I. [Brown University] — Newspaper endorsements for presidential candidates can influence voting decisions, according to new research by two Brown University economists. In a working paper, Brian Knight and graduate student Chun Fang Chiang demonstrate that voters are more likely to support the recommended candidate following the publication of an endorsement, but any degree of influence depends on the credibility of the paper’s pick.

The researchers take into account that newspapers are potentially biased in favor of one of the candidates and found that voters rationally account for the credibility of any endorsement. That is, endorsements for the Democratic candidate from left-leaning newspapers are less influential than endorsements from neutral or right-leaning newspapers and likewise for endorsements for the Republican candidate. Knight said these results “suggest that voters are sophisticated and attempt to filter out any bias in media coverage of politics.”

To estimate the influence of newspaper endorsements, the researchers used individual-level data on voting intentions and newspaper readership in the months leading up to the 2000 and 2004 elections. They measured endorsement credibility based on the ideological leanings of newspapers, ownership, and reader preferences.

To provide a sense of the magnitude of endorsement effects, Knight and Chiang feature a data table that shows the estimated influence in the top 20 newspapers during the 2000 presidential campaign. They show the least credible endorsements were for Al Gore from The New York Times and for George W. Bush from the Dallas Morning News, which convinced less than 1 percent of their readers to switch allegiance to the endorsed candidate. By contrast, the endorsement with the largest effect came from the Chicago Sun Times, which was predicted to endorse Gore with a probability of 58 percent, but instead endorsed Bush. This endorsement convinced about 3 percent of readers to switch allegiance from Gore to Bush, according to the findings.  

These findings are particularly interesting considering the 2008 presidential endorsements. According to Editor and Publisher Magazine, more than 27 newspapers that backed George W. Bush in 2004 have endorsed Obama this year (as of Oct. 22), including large papers such as theDenver Post, Chicago Tribune and New York’s Daily News.

“We expect these Obama endorsements to be particularly influential since they have more credibility than endorsements from newspapers that always support the Democrat,” said Knight, associate professor of economics and public policy.

 A full copy of the paper is available to download (PDF) from Knight’s research web site. 

October 9, 2008

Professor to Speak on NASA’s Exploration of Moon and Planets

Filed under: et.al., Media, Science — Tags: , , , , , — David Kirkpatrick @ 5:00 pm

Press release from today. Sounds like a cool talk.

Professor to Speak on NASA’s Exploration of Moon and Planets

HAMPTON, Va., Oct. 9 /PRNewswire-USNewswire/ — The launch of Sputnik energized NASA’s exploration of the solar system, including the moon and all eight planets. According to Dr. James Head, a distinguished professor of Geological Sciences at Brown University, it was NASA’s exploration that “provided a new understanding of how the Earth and other planetary bodies formed and evolved.”

(LOGO:  http://www.newscom.com/cgi-bin/prnh/20081007/38461LOGO )

Head will speak on what he calls the “missing chapters of Earth history” in a colloquium lecture called “The Exploration of the Moon and Planets: A New Perspective on Earth” on Tuesday, Oct. 14, at 2 p.m. in the Reid Conference Center at NASA Langley. The talk is part of a series celebrating NASA’s 50th anniversary.

He will present the same lecture for the general public on Tuesday evening at 7:30 p.m. at the Virginia Air & Space Center on Settlers Landing Road in Hampton. The evening talk is free and no reservations are required.

Head is currently researching the processes that form and modify planetary surfaces. He also studies comparative planetology and the themes of planetary evolution, and looks for application of these to the study of early Earth history. He has conducted field studies on active volcanoes in Hawaii and at Mount St. Helens and on volcanic deposits on the seafloor with two deep-sea submersible dives.

Before his time at Brown University, Head worked with the NASA Apollo Lunar Exploration Program, where he helped select potential landing sites and train the Apollo astronauts. He also worked in mission operations and analyzed the returned lunar samples.

For more information on NASA Langley’s Colloquium and Sigma Series lectures, visit:

http://shemesh.larc.nasa.gov/Lectures/colloq/colloqsigma.htm

Photo:  http://www.newscom.com/cgi-bin/prnh/20081007/38461LOGO
AP Archive:  http://photoarchive.ap.org/
PRN Photo Desk photodesk@prnewswire.com
Source: NASA
   
Web Site:  http://www.nasa.gov/