Since its launch in 1984, the VW Beetle-sized craft has circled Earth at an altitude of about 700 kilometers more than 130,000 times — once every 99 minutes, says Kristi Kline, program manager for Landsat at the U.S. Geological Survey’s Center for Earth Resources Observation and Science in Sioux Falls, S.D.

Sensors on the polar-orbiting craft collect data at seven different wavelengths from near ultraviolet to the far infrared. Except for central Antarctica and far northern Greenland, the satellite passes over each spot on land once every 16 days, and can distinguish features as small as 30 meters across, Kline notes. http://louisdjdsheehan.blogspot.com

Besides providing before-and-after shots of landscapes that have suffered natural disasters such as volcanic eruptions, floods, tsunamis or hurricanes, the archive of Landsat data — 2.3 million images strong and gathered since Landsat 1 launched in 1972 — also chronicles the effects of human activity such as urban sprawl and deforestation.  Louis J. Sheehan, Esquire.

So why has Landsat 5, originally designed to operate just three years, lasted so long? In part, because the craft was designed with extra fuel capacity so it could occasionally be brought to lower orbit and serviced by astronauts onboard the space shuttle — a feature that hasn’t been used. The fuel instead has served to keep the satellite in orbit and oriented properly. “That, plus some really good engineering and a lot of luck,” Kline adds.

Hitting “print” is easy. Getting a perfect printout is not. All too often, inkjet printers spew out smudged or smeared pages. Now, a new study of the physics of ink concludes that the culprit is the gloopiest ink.

Inkjet printers have a tiny nozzle, or inkjet, that squirts droplets of ink onto the paper as it passes through. Ideally, the ink forms into a perfect round droplet as it launches from the inkjet, hitting the paper right on target. But droplet formation is affected by ink properties including density, surface tension and viscosity, which is the measure of resistance to flow or “gloopiness.” And if the droplets aren’t just right, a splotch appears instead of a crisp line of text, the researchers say.

Scientists use a ratio called the Z number to describe the surface tension and viscosity of a particular ink. Inks with lower Z are more viscous, while inks with higher Z have more surface tension, explains material scientist and study coauthor Jooho Moon of Yonsei University in Seoul, Korea.

Recent theoretical work found that the most printable inks would have Z values between one and 10. But the new research suggests the best droplets form from inks with Z values between four and 14, Moon and his colleagues report in the March 3 Langmuir. That means, of the inks now in common use, the more free-flowing ones print better, Moon says.

“A kind of balance is what is needed for the most printable inks,” explains material scientist Damien Vadillo of the University of Cambridge in England.

When ink is launched from the inkjet, a teardrop-shaped ball hurtles toward the paper. The teardrop elongates until a tail of ink, called a filament, stretches away like the tail of a comet.

In the study, researchers captured images of the droplets of different types of lab-made inks, up to a Z score of 17. Inks with Z values above 14 had filaments that easily broke away from the ink drop, forming a secondary ink drop that created a smear. Droplets of inks with Z values below 14 held together better, and the viscosity of the ink pulled the filament back into the droplet. But droplets of very viscous inks with Z values below four stuck to the inkjet instead of launching properly, the scientists note.

The researchers acknowledge in the paper that the work only tested ink on one printer, and the best Z values could vary slightly depending on how far a printer’s inkjet is from the paper’s surface.

Despite the new range of Z values, it’s not necessary to rush out to purchase new ink cartridges. The study’s conclusion “is not really a big surprise, just refining what we already knew,” Vadillo says.

But understanding the properties of the most printable inks will help in future printer and ink design. And inkjet printers are useful for more than desktop publishing. http://louisdjdsheehan.blogspot.com  “Droplets of chemicals could be printed onto a substrate, then we could test thousands of different reactions at once,” Vadillo speculates. “Understanding how to make the chemicals into good ‘inks’ will help us to do that.”  http://louisdjdsheehan.blogspot.com

Bone and chemical analyses indicate horses were harnessed and even milked more than 5,000 years ago in central Asia

By Bruce Bower

Web edition : Thursday, March 5th, 2009

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A horse's tooth found at an ancient settlement in Kazakhstan displays parallel bands of wear (at left) typically produced by bits held in the mouths of bridled animals, researchers say.Science/AAAS

Central Asia’s vast grasslands hosted a prehistoric revolution in transportation, communication and warfare, thanks to the humble horse. Remains from Kazakhstan’s more than 5,000-year-old Botai culture have yielded the earliest direct evidence for domestication of these versatile beasts, scientists report.

The Botai people were hunter-gatherers who lived in large settlements for months or years. Their culture lasted from 5,600 to 5,100 years ago. Researchers have long suspected that the Botai rode domesticated horses while hunting for wild horses to eat but did not domesticate other animals or cultivate crops.

Butchered horse remains found at four Botai sites include two tell-tale signs of domestication: slender lower-leg bones like those of later domesticated horses and cheek teeth worn down by bits that attached to bridles or similar restraints, says a team led by archaeologist Alan Outram of the University of Exeter, England.

Chemical analyses of animal fat residue on the inside surfaces of Botai pottery fragments suggest that the vessels had once held mare’s milk, probably gathered in summer months, the researchers report in the March 6 Science. Modern Kazakh horse herders milk mares in the summer to produce a fermented, alcoholic drink called koumiss.

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A villager in northern Kazakhstan milks a mare, much as members of the Botai culture must have done more than 5,000 years ago, a new study concludes. A. Outram

Milking of horses and other animals arose in areas, such as northern Kazakhstan, that lacked agricultural practices often regarded as precursors of milking, Outram and his colleagues propose.

“This is certainly the earliest culture by some margin with such compelling evidence for domesticated horses,” Outram says.

The new report presents the first evidence for horse milk in Botai pots and for Botai horses having domesticated-looking leg bones, remark David Anthony and Dorcas Brown, archaeologists who teach at Hartwick College in Oneonta, N.Y., who study the origins of horse domestication. “If you’re milking horses, they are not wild,” Anthony says.

Outram’s group compared 18 lower-leg bones from Botai horses, excavated in 2005 and 2006, to corresponding bones already excavated by others at sites of the nearby, roughly 5,000-year-old Tersek culture. Comparisons were also made to leg bones from modern and 3,000-year-old domesticated horses and from wild Siberian horses that lived more than 20,000 years ago. Botai horses displayed the relatively slender legs of domesticated animals. Tersek horses’ legs looked more like those of wild horses.

Additionally, one Botai horse molar displayed deep, parallel grooves typically observed on the molars of domesticated horses that hold bits in their mouths, Outram says. Bits may also have produced less-pronounced tooth wear on two other Botai horses. Evidence of bone damage and regrowth appeared on four Botai horses’ jaws where bits or bridles would have rubbed through gums.

The evidence of bit use described by Outram’s team is interesting but preliminary, according to Anthony and Brown. Researchers are still debating whether other proposed signs of bit damage on Botai horses’ teeth, reported by Anthony and Brown in 1989, might instead have resulted from natural causes.

The Botai people didn’t invent horse domestication and milking, Anthony and Brown propose. These practices were borrowed from inhabitants of the nearby Russian steppes, who included possibly domesticated horses in sacrificial rituals with domesticated sheep and cattle by 6,500 years ago, they say. Those Botai neighbors probably domesticated horses after learning about cattle and sheep domestication from farming groups, in Anthony and Brown’s view.

If copying is the sincerest form of flattery, then journals are publishing a lot of amazingly flattering science. Of course to most of us, the authors of such reports would best be labeled plagiarists — and warrant censure, not praise.

But Harold R. Garner and his colleagues at the University of Texas Southwestern Medical Center at Dallas aren’t calling anybody names. They’re just posting a large and growing bunch of research papers — pairs of them — onto the Internet and highlighting patches in each that are identical.

Says Garner: “We’re pointing out possible plagiarism. You be the judge.” But this physicist notes that in terms of wrong-doing, authors of the newest paper in most pairs certainly appear to have been “caught with their hands in the cookie jar.”

Garner's team developed data-mining software about eight years ago that allows a resarcher to input lots of text — the entire abstract of a paper, for instance — and ask the program to compare it to everything posted on a database. Such as the National Library of Medicine's MEDLINE, which abstracts all major biomedical journal articles. The software then looks for matches to words, phrases, numbers — anything, and pulls up matches that are similar. The idea: to help scientists find papers that offer similar findings, contradictions, even speculations that might suggest promising new directions in a given research field.

Early on, Garner says, his team realized this software also had the potential for highlighting potential plagiarism. But that was not their first priority. In fact, his group didn't really begin looking in earnest for signs of copycatting until about two years ago.

Today, Garner’s group has published a short paper in Science on results of a survey it conducted among authors of pairs of remarkably similar papers (identified from MEDLINE), and the editors who published those papers. The Texas team wanted to find out whether the apparent copycats — not only the authors but also the editors who published their work — would own up to plagiarism. And once confronted with this public finger pointing, what would they do about it?

The real surprise, says Garner — indeed, “the shock” — was that so few authors of the initial papers were aware of the copycat’s antics. Prior to emailing PDFs that highlighted identical passages in each set of paired papers, 93 percent said they had been unaware of the newer paper.

Since those newer papers were all available via MEDLINE searches, they should have come up every time authors of the first paper searched for work on topics related to their own. In fact, Garner points out, because MEDLINE posts search results in reverse chronological order, copycatted papers should turn up before the papers on which they had been based.

To date, 83 of the 212 pairs of largely identical papers identified so far by the data-mining software that Garner’s team has developed have triggered formal investigations by the journals involved. In 46 instances, editors of the second papers have issued retractions. However, what constitutes a retraction varied considerably. It might have been broad publication of problems with the offending second paper — both in the journal and in a notice sent to MEDLINE.

Other times, some website might have acknowledged the retraction of some or all of a paper, with no notification of the problem forwarded to MEDLINE. In such cases, Garner notes, anyone using MEDLINE's search function would get no warning that the abstract it pulled up relates to findings that have been discredited.

Have you ever shared this material on apparent plagiarism with the administrators of the second paper's authors, I asked Garner. "No, that would have put us into this situation where we would be acting more as police or an investigatory body," he said. And they're not anxious to serve as honesty cops.

Too bad.

So far, his team's software has turned up more than 9,000 'highly similar' papers in biomedical journals indexed by MEDLINE. And only 212 are copycats? Actually, Garner says, that estimate is probably way low. Of that big number, "We have only gotten through looking at 212 so far." Their investigations continue.

For more on the implications of such copycatting, check out my next post.

A standard chemotherapy drug may make a small but aggressive population of brain cancer cells even more deadly, a study in the March 6 Cell Stem Cell reports. Understanding how these cells turn dangerous may ultimately lead to better ways to destroy brain tumors.

“This really shows how important it is that we have therapies against different populations of cells,” says Anders Persson of the University of California, San Francisco, who coauthored a commentary in the same issue of Cell Stem Cell. “You can’t just give one treatment and think it will kill every cell.”

The most common cancer originating in adults’ brains — glioblastoma multiforme — is particularly complex and notoriously resistant to standard treatments. The resistance may be caused by small numbers of cancer cells called side populations, says Eric Holland, a neurosurgeon at Memorial Sloan-Kettering Cancer Center in New York City and coauthor of the new study.

The new study finds that these side population cells make up only 4 to 8 percent of all cells of a mouse brain tumor. And the cells may be able to produce multiple types of cancerous cells with different properties and rebuild the entire tumor from the ground up, like the noncancerous stem cells that can create entire organs.

Currently, a drug called temozolomide is the first-line treatment for glioblastoma in humans. When brain tumors are treated with temozolomide, many cancerous cells die, but the side populations live on in greater numbers, the new study shows. When treated with the drug, side populations of mouse cancer cells grew to make up as much as 30 percent of all cancerous cells, Holland and his team found.

When researchers applied temozolomide to mouse cancer cells lacking a known cancer-preventing gene PTEN, the side population cells made up 75 percent of all cancer cells. 

The new work supports the idea that “the treatment we throw at tumors” affects these small but dangerous populations of cancer cells, comments William Weiss, a neurologist at the University of California, San Francisco who coauthored the Cell Stem Cell commentary.

The researchers also tested temozolomide’s effects on how quickly tumors from side populations grow. On average, tumors formed after 25 days in cancer-free mice that were implanted with temozolomide-treated side population cells, while untreated cells took more than 40 days to grow into tumors.

Temozolomide may select for the most aggressive of the already aggressive side population cells, Holland suggests.

“The few cells that survive come roaring back and kill the patient.” But he does not advocate changing treatments: “It’s very clear that with temozolomide, patients survive longer.”

Whether these side populations of cancer cells are truly stem cells, with the capacity to grow back a complex cancer, is still unclear. The notion is “a very attractive hypothesis” that may help explain why chemotherapy treatments don’t always cure cancer, says Weiss. Louis J. Sheehan, Esquire