Martinez A.,University of Iowa |
Spak S.N.,University of Iowa |
Spak S.N.,the University of Iowa |
Petrich N.T.,University of Iowa |
And 3 more authors.
Atmospheric Environment | Year: 2015
Indiana Harbor and Ship Canal (IHSC) in East Chicago is an industrial waterway on Lake Michigan and a source of PCBs to Lake Michigan and the overlying air. We hypothesized that IHSC is an important source of airborne PCBs to surrounding communities. We used AERMOD to model hourly PCB concentrations, utilizing emission fluxes from a prior study and hourly meteorology provided by the State of Indiana. We also assessed dispersion using hourly observed meteorology from a local airport and high resolution profiles simulated by the Weather Research and Forecasting model. We found that emissions from IHSC waters contributed about 15% of the observed ∑PCB concentrations close to IHSC when compared on an hourly basis and about 10% of observed annual concentrations at a nearby school. Concentrations at the school due to emissions from IHSC ranged from 0 to 18,000 pg m- 3, up to 20 times higher than observed background levels, with an annual geometric mean (GSD) of 19 (31) pg m- 3. Our findings indicate that IHSC is an important source of PCBs to East Chicago, but not the only source. Four observed enriched PCB3 samples suggest a nearby non-Aroclor source. © 2015 Elsevier Ltd.
In the 1967 animated Disney film The Jungle Book, the feral boy Mowgli encounters a jazz-singing orangutan named King Louie, who implores Mowgli to teach him the secret of fire. King Louie presented a challenge for the producers of Disney’s live-action, CGI-enhanced remake of the film, opening April 15. “We had this notion that we would be as authentic as we could be to the region,” says producer Brigham Taylor. The problem: Orangutans are not native to India. In fact, King Louie himself is not native to Rudyard Kipling’s original stories. But instead of scrapping the character, the filmmakers got creative. While researching India’s wildlife, the film’s art department learned that a colossal ape named Gigantopithecus once roamed the region. Various species of Gigantopithecus lived in India, China and Southeast Asia from about 6.5 million years ago until as recently as a few hundred thousand years ago. The ape was truly gigantic — by some estimates, twice as big as a gorilla. So King Louie morphed from orangutan to Gigantopithecus. The switch was a “fun justification,” Taylor says, to keep the character and play up his size while still staying true to India’s fauna. (Yes, the ape is extinct, but this is a movie about talking animals. And fossil evidence does suggest that the ape at least mingled with the human ancestor Homo erectus.) Using the scientific information they could find on the Internet, visual effects artists imagined how the animal would look and move, Taylor says. The result: an ape that resembles an overgrown orangutan, Gigantopithecus’ closest living relative. The movie ape has shaggy hair, flaring cheeks and a saggy pouch that hangs from the throat like a double chin — and towers about 12 feet tall. It’s difficult to judge how accurate Disney’s rendering is. Despite possibly having been the largest primate ever to have lived, Gigantopithecus left behind few fossils. Scientists have just four lower jaws and over a thousand teeth, says biological anthropologist Russell Ciochon of the University of Iowa. That’s not much to go on, but Ciochon and colleagues made their own reconstruction a couple decades ago. The researchers took a jaw from China and made an outline of a skull that could fit such a jaw. Because most primate skulls scale to body size, Ciochon says, his group could estimate Gigantopithecus’ weight, 800 to 900 pounds, and height, about 9 feet from head to toe. (The species that lived in India was actually probably smaller.) Adding other details like hair to the animal is a matter of conjecture, Ciochon says. But the teeth do offer some solid details about the ape’s lifestyle. Wear patterns and microscopic debris stuck to the teeth indicate Gigantopithecus dined on fruits, leaves, shoots, roots and perhaps even bamboo. Last year, researchers confirmed those details after analyzing the ratios of carbon isotopes in teeth found in Southeast Asia. The analysis also determined that Gigantopithecus was a strict forest dweller, even though it also lived near grasslands in some areas. In fact, the researchers contend, Gigantopithecus’ reliance on forests and its big size — and therefore big appetite — may have been the animal’s undoing. As Southeast Asia’s jungles gave way to expanding grasslands during the last glacial period, Gigantopithecus may have been unable to cope. Perhaps if our ancestors had shared the secret of fire with Gigantopithecus, the giant ape would still be around today.
News Article | September 5, 2016
What could we do without fear? I, for one, could interface with more than one other human simultaneously without drinking all of the alcohol. That would be OK. I might be a better rock climber, though I might also be a more reckless, dangerous rock climber. I guess it would really be a big package deal, where fear and its anxiety kin just stop making sense. A lot of things would be more boring, I think. This isn't strictly a theoretical idea. In a famous case, a patient known as SM has managed to live most of her life with no fear thanks to a rare calcification of her amygdala, the region of the brain most associated with the emotion. Her actual identity is closely guarded, but NPR's Invisibilia managed a rare interview with her in an episode last season. It's worth listening to (see: "Fearless"). That episode is why some research published today in Nature Neuroscience especially caught my eye. It describes a "new pathway for fear." Neuroscientists have some understanding of the routes leading from the various sensory organs that converge in the amygdala, but less so about those running in the opposite direction. In other words, we know how information makes it from the outside world to the formation of fear-memories, but not so much how those fear-memories are accessed again as, well, fear. The new paper describes an opposing pathway running from the lateral amygdala (LA) to the auditory cortex (ACx), which was discovered by the researchers using electron microscopy and fear conditioning in mice. The circuit appears to have a role in the process of expressing learned defensive responses to sounds. We have fear-sounds, integrated into fear-memories, and we have learned defensive reactions to these sounds. This is where all of that comes from. The group behind the new paper, a large team based at the Shanghai Institutes for Biological Sciences, further explored this using mice who had had their LA to ACx circuit limited either chemically or by using optogenetics (where light is able to control various brain functions via cells genetically-engineered to respond to it). "To determine the function of this previously uncharacterized LA–ACx pathway, the authors trained mice with auditory fear conditioning," explains Bo Li, a neuroscientist at Cold Spring Harbor Laboratory, in a separate Nature Neuroscience commentary. "After the training, normal mice would freeze in response to the sound. However, in mice in which the LA–ACx pathway was specifically inhibited by either chemogenetics or optogenetics during the memory recall test, sound no longer induced freezing. In other words, the LA–ACx pathway is necessary for the recall of the aversive memory." What's weird is that this doesn't seem to work in the other direction. If you block the pathway leading from the auditory cortex to the amygdala, fear-inputs still manage to get through and form fear-memories. We're really just now starting to get a handle on all of this. In any case, it at least seems very likely that we will eventually be able to manipulate our fear machinery in useful ways. But SM, the fearless patient, is also an illustration of what fear even is. For one thing, as one of the many doctors studying her, the University of Iowa's Daniel Tranel, told NPR's Science Friday in 2010, fear is not the same as worry. And, thus, it is not necessarily the same thing as anxiety. "There's a very fundamental difference between fear and worry, and she does worry," Tranel explained. "Worry is more in the domain of anxiety and has a lot to do with something we humans do a lot of, which is the future, spending time in the future." And the future, it seems, is something we're stuck with.
Batman is perhaps the most high maintenance of any superhero: An arsenal of high-tech gadgets working together in batty synchrony provides assistance against in his never-ending war on crime. His Bat Mobile would be vulnerable without his Bat Cave. And he would be helpless without his old friend Robin. The human body—known in some circles as a superorganism—is not all that different from a high-maintenance superhero. We, too, have different munitions that work in harmony towards our war against pathogens. Or, at least, we had them. At one point in the not too distant past we had three lines of defense against disease: the immune system, the microbiome, and fauna, like intestinal worms. William Parker, an immunologist at Duke University Medical Center likens these lines of defense to a three-legged stool to illustrate this relationship. The extinction of any one of the legs has the potential to seriously weaken our defenses against pathogens. As it turns out, this may have already happened. The intestinal worms, known as helminths, are part of the macrobiome—a term largely unknown in the realms of the general public and science nerds alike. This is partly due to the fact that current research on the macrobiome is dwarfed by the over-abundance of research on the microbiome (ironic, isn’t it?). But more likely it’s a novel term due to the fact that since the 1960s, in developed nations, we’ve all but eradicated the macrobiome. Without that third leg, our defense system collapses. The immune system has evolved alongside worms and bacteria in an evolutionary tug of war. The worms and bugs would attack, and the immune system would evolve a counter defense. Now there’s growing evidence that the constant pressure actually helped tone and develop our immune systems as our immunity evolved along with the worms and bugs that lived inside of us. Without that constant pressure our immune systems have an annoying tendency to over-react, much like the Hulk, blowing out of proportion over that harmless pollen grain that could trigger allergic responses, and misinterpreting our own bodies as something that needs to be destroyed, as can be seen in autoimmune disorders. “The idea is that we’re so far out of our evolutionary adaptedness that our immune systems are very dysregulated,” Parker says. Parker’s claim is bold, but not completely batty. Researchers at the University of Michigan had a similar hunch when, in 2010, they took on the brave task of trying to dissect the interconnected web of human immunity. They wanted to know what happens to the microbiome in the presence of worms. “I started looking at the microbiome before it was fashionable,” says Vince Young, associate professor of microbiology and immunology at University of Michigan and senior author on the 2010 study. His research had been focused on mouse models of inflammatory bowel disease (IBD) and bacterial GI infection but, as he pointed out, “We were ignoring everything else that’s going on in there.” It had been known for some time from research in Joel Weinstock’s lab, then at the University of Iowa, that giving helminths to mice with IBD improved the symptoms of IBD and could offer a protective benefit even before symptoms occur. Weinstock’s group went on to show this in humans, as well. So the Michigan team joined forces with Weinstock to investigate further. They conducted an experiment comparing the microbiome profiles of helminth-infected mice to non-infected mice testing their hypothesis that helminths would alter the gut microbiome. And that’s exactly what they found. Their study allowed the researchers to show that, yes, worms did do something to the microbiome. But, we “need to figure out what is really going on,” Young says. Noted in their paper is the statement that they had no idea what the heck it all meant in terms of clinical importance...in not so many words. But like any good study, it prompted more questions. In a recent study published in Gut Microbes in March 2015, Parker’s group conducted a follow up and found a strikingly similar result. His group went a step further by characterizing the shifts in the gut microbes that they were seeing. They found that by adding a single helminth they saw the microbiome shift to a much more “healthy-looking” state. “It’s very difficult to decipher the fingerprint of a healthy microbiome,” admits Erin McKenney, a Ph.D. candidate in the biology department at Duke University, and lead author on the study. “But, what you can do is eyeball these big shifts in bacterial communities.” A huge chunk of the bacterial demographic changes from a more “fend for yourself type of organism,” to bacteria that have a deep evolutionary history of working with a host, she says, adding that helminths should have a slogan: “Helminths for a better partnership.” So, what are the implications of studies like Young’s and Parker’s? “We need to look at the biome as a whole and not the microbiome in isolation,” Parker says. He might be on to something. Although these interactions between the host immune system and the biome are dizzyingly complex, imagine if allergies and autoimmune diseases could be treated by introducing a worm or fiddling with our microbiome—or fiddling with the microbiome with worms. “I think within five years, as more and more data with the effects of the helminths come out, things are going to change,” Parker says. “Altering the microbiome itself is not curing disease, but altering the biome as a whole is having a profound effect.”
More than 30 universities have banned or restricted hoverboards on their campuses in recent weeks, saying the two-wheeled, motorized scooters are unsafe. Beyond the risk of falls and collisions, colleges are citing warnings from federal authorities that some of the self-balancing gadgets have caught on fire. "It's clear that these things are potentially dangerous," said Len Dolan, managing director of fire safety at Kean University in Union, New Jersey. The public school of 14,000 students issued a campus-wide ban effective on Monday, telling students in an email that any hoverboards found on campus would be confiscated. "These things are just catching fire without warning, and we don't want that in any of our dorms," Dolan said. Outright bans also have been issued at schools such as American University and George Washington University, both in Washington, D.C. Other schools said they will forbid the scooters in dorm rooms or campus buildings, a policy adopted at colleges including Louisiana State University, the University of Iowa and the University of Arkansas. After banning hoverboards from dorms in December, officials at the University of Hartford in Connecticut are now considering a full ban because of concerns over how to store them safely, said David Isgu, a school spokesman. Some of the reported fires have occurred while the boards were being charged, authorities say. At Ohio State University and at Xavier University in Cincinnati, students were told they can bring a hoverboard only if it came with a seal showing that the board meets certain safety standards. Schools have issued bans as recently as Thursday, when the University of Connecticut announced that the devices aren't welcome on campus. The University of Alabama and the University of Kentucky declared bans on Wednesday as students prepare to return from break. "We are not willing to risk your safety and our community's safety," University of Kentucky Fire Marshal Greg Williamson told students in a statement. Bryce Colegrove, a sophomore at Shawnee State University in Ohio, got an email from his school on Tuesday telling students to leave their hoverboards at home after the holidays. It was bad timing for Colegrove, who had just received one as a gift from his girlfriend and had even plotted his new routes to class. "Honestly I was really disappointed," said Colegrove, 20. "I don't think it's right to ban them. I mean, it's a college campus; it's not a high school." Others took to social media to voice their frustration, with some saying they planned to bring their scooters to school anyway. Hoverboards, which are made by several brands, already have been banned by the three largest U.S. airlines, citing potential fire danger from the lithium-ion batteries that power them. The devices also are prohibited on New York City streets, and a new law in California requires riders to be at least 16 and wear a helmet in public. On Monday, the U.S. Consumer Product Safety Commission reported that it's now investigating 28 fires in 19 states tied to the motorized scooters. Fire officials from New Jersey to California have blamed the boards for fires that damaged homes. The federal commission also said there have been serious injuries caused by falls. Colleges reported that even though the gadget has been gaining popularity, it's still relatively rare on campuses. Dolan, of Kean University, said he saw about six students riding the scooters last fall. News of swift sales over the holidays, plus the reports of fires, led him to propose the ban. "If that may inconvenience a couple dozen students, then that's what it's going to have to be," he said. Fire officials in several states have issued their own warnings about the devices, including in New Jersey, were authorities recommended that all public colleges ban them. Still, several colleges have suggested that they may allow hoverboards in the future. American University said its ban is temporary, but will last "until further notice." At Wellesley College near Boston, a policy bans the motorized scooters "until safety standards can be developed and implemented by the manufacturers." Explore further: U.S. colleges going smoke-free
In Lewis Carroll's book Through the Looking Glass, the Red Queen tells Alice, "It takes all the running you can do, to keep in the same place." Evolutionary biologists have drawn from the phrase to hypothesize that organisms engage in sexual reproduction to keep pace with an ever-changing world. They contend that male-female mating—factored over generations—produces offspring with enough genetic diversity to resist varied, evolving threats—from disease to changed climate. A team of biologists led by the University of Iowa further scrutinized the hypothesis by testing whether female New Zealand freshwater snails that reproduce sexually would be more resilient to outside perils than females that produce offspring by themselves. The researchers documented the concentration of sexual females and asexual females at multiple sites in the same lake and compared how their populations were affected by a parasitic worm commonly associated with the snails. The researchers found that in areas of the lake where the worm was prevalent, male snails were plentiful (indicating sexually reproducing female snails were present). They even found male snails roaming in areas where the parasite concentration was as low as four percent, as well as in higher numbers where parasite activity was heavier. The results offered another encouraging sign that sexually produced offspring are getting a genetic boost from mommy and daddy. For instance, the offspring get two genetic blueprints (one from each parent), rather than just their mother's genome, which they would if they were born to an asexual female. Viewed over generations, sexual reproduction can produce new gene combinations that are needed to deal with changing environments. "These results are consistent with the idea that there are advantages to sex related to the ability to produce diverse offspring," says Maurine Neiman, associate professor in biology at the UI and corresponding author on the paper published this week in the New Zealand Journal of Ecology. "Snails born with rare gene combinations would be harder to infect because the parasites have rarely, if ever, encountered those shuffled genetic combinations." Neiman and others in her field have been studying the freshwater snails for years, in large part because some females can bear offspring without males. The snails also are vulnerable to a well-documented threat—a parasitic worm (Microphallus livelyi) that lives within the snail as it awaits a chance to glom on to its final host: ducks that eat infected snails. Previous studies have shown an association between parasite concentration and the number of sexual female snails. Where parasite activity is low, sexual females are few; where parasite activity is high, sexual females are abundant. This study adds to other analyses linking parasite activity to sexual and asexual female populations within a small mountain lake, Lake Grasmere. This study is distinctive because the researchers found dramatic differences in the percentage of female sexual and asexual snails (using males' presence as a proxy) and parasite prevalence between sites as close as two football fields apart, "suggesting that these evolutionary links between sex and parasites can operate at a remarkably small scale," Neiman says. Neiman and her colleagues think the parasitic worm invades the snail by tricking its immune system into believing it's not a threat. Some diseases do the same with humans, fooling our immune system just enough to lodge themselves within our bodies and make us ill. Yet, over time, humans have inherited and passed down new gene combinations that protect better against those diseases. That's genetic diversity and natural selection at work. Like humans, the snails' best defense against the parasitic worm is to pass down gene combinations that are new to the parasite. That shuffling of genes is much more likely to occur through male-female mating than asexual reproduction, where the daughter inherits her mother's exact genetic makeup. The team visited Lake Grasmere in January 2014. There, 25 undergraduates from Carleton College, in Minnesota, assisted Neiman and the paper's first author, Carleton College biologist Mark McKone, by collecting 1,800 snails at 18 sites, either on foot or by kayak, and examining each under a microscope to catalog sex and infection rates. Five Carleton undergraduates are included as authors on the paper. "The students who took the lead on the project helped in all aspects of the research, including framing the experimental question, organizing data collection, analyzing the results, and ultimately submitting a manuscript for publication," McKone says. "It is rare for undergraduates to gain such broad exposure to the complete process of science." Explore further: Study finds role for parasites in evolution of sex
News Article | December 29, 2015
Scientists from the University of Iowa have determined that a particular liver hormone may tell our brain when it's time to put down the candy bars. It's called FGF21, and when released, it causes the body to crave less sugar. "This is the first liver-derived hormone we know that regulates sugar intake specifically," says Matthew Potthoff, co-senior author on the paper, in a press release. Researchers have known for some time that certain hormones can affect appetite, but this is the first study showing a specific hormone is tasked with regulating the intake of a macronutrient. One conclusion could be that people with a pronounced "sweet tooth" may have low FGF21, or fibroblast growth factor 21, production. The hormone has also been linked to insulin sensitivity. The research involved injecting specially-engineered mice with FGF21 and observing their appetites. The mice given the hormone ate a seventh as much sugar as they did before the injection. The scientists also noted that the hormone didn't cause the animals to eat fewer complex carbs. The role of FGF21 has not yet been studied in humans. "We've known for a while that FGF21 can enhance insulin sensitivity," says Lucas BonDurant, also a co-author of the study. "Now, there's this dimension where FGF21 can help people who might not be able to sense when they've had enough sugar, which may contribute to diabetes." The next step will be to find out which parts of the brain respond to FGF21, so that this research might be turned into treatment. It will also give a hint as to where to look for hormones that regulate other macronutrients, like fat and protein. According to the Centers for Disease Control and Prevention, 29 million Americans, fully 9 percent of the population, have diabetes. More than a third of U.S. adults are obese. The research on FGF21 was published online in the journal Cell Metabolism.
News Article | January 29, 2016
Here’s more good news for fuel cell electric vehicle fans: the California company HyperSolar, which has been developing a system for producing hydrogen with an assist from solar energy, has announced a new tweak that will help bump down the cost of its process. If all goes well the result will be a competitive price for hydrogen fuel with which to fuel up your new FCEV. CleanTechnica first took note of HyperSolar back in 2011, when it patented a process for making renewable hydrogen with solar energy. In 2012 we described the company’s vision for large scale solar farms that mimic photosynthesis and “split” water to produce hydrogen instead of veggies, but the company dropped off our radar after that. We should have been paying more attention because a lot has happened since then. Among the recent developments, earlier this month HyperSolar renewed its sponsored solar powered hydrogen production research program with the University of California – Santa Barbara for another six months. That follows on the heels of an announcement last December, in which the company noted some progress in developing a new solar powered water-splitting catalyst. The new catalyst eliminates the need for more expensive materials — namely, platinum — which is a key factor in the cost of solar powered hydrogen production. In its latest announcement, HyperSolar reports that test results have been promising: Test results indicate that this low cost catalyst will reduce overall voltage requirements, significantly increase photocurrents, improve hydrogen production efficiency, and further reduce the cost of the Company’s hydrogen production process. HyperSolar’s press materials are a bit thin on the details about that new catalyst, except to note that it was developed by Syed Mubeen Hussaini of the University of Iowa. We took a little stroll through the Intertubes to find out more so this is just a wild guess, but that could be the one described in a study published last year by the Electrochemical Society, authored with fellow University of Iowa researchers Wei Cheng and Alan M. Rassoolkhani under the title “Low-Cost Synthetic Routes for Fabricating Tandem/Multi-Junction Photoelectrochemical Devices.“ In the study, the authors note the efficiency limitations of water-splitting catalysts based on a single material. The use of combinations of materials (aka multi-junction) boosts efficiency, but results in an overly complex, expensive device. The solution they propose is a photoelectrochemical device that uses a low cost process to deposit an inexpensive, efficient metal oxide/sulfide onto a conventional silicon solar cell. The metal acts as an anode, and the solar cell itself acts as a cathode. Last fall HyperSolar renewed its research relationship with the University of Iowa to April 2016, so it looks like additional improvements are expected. Here’s the company’s rundown on the progress with both research partners as of last fall: The Company announced in September 2015 that it had surpassed 1.5 Volts (V), the practical voltage needed to effectively split water molecules to produce hydrogen in real world systems…The collaboration between the two Universities led to the rapid development of the technology, as the Company surpassed both the theoretical minimum (1.23 V) then the recent 1.55 V breakthrough, within one year. CleanTechnica has generally given hydrogen fuel cell electric vehicles the stinkeye for a number of reasons, including the use of fossil natural gas to produce hydrogen fuel. Deploying solar energy to generate renewable hydrogen from water leaps over that hurdle, though it does raise the potential for water scarcity issues. On the other hand, potable water is not necessarily an issue for renewable hydrogen. HyperSolar is among a number of companies and research institutions that are developing solar-powered processes that can run efficiently on non-potable water, including water drawn directly from rivers and other natural sources as well as wastewater from industrial operations. Seawater is another potential source of hydrogen. Last year, for example, we noticed the US Navy’s interest in a transportable system that could be used to produce fuel on the go. The primary purpose is to capture carbon dioxide from seawater and convert it to a usable carbon-based fuel, but the contraption also produces hydrogen as a byproduct. As for fuel cell EVs, Toyota is a big fan, and the company has been exploring the “hydrogen economy” concept in Japan. Toyota has already rolled out its Mirai FCEV in California, thought there appears to be a glitch (we’re thinking a temporary one) in terms of hydrogen fuel station availability In addition, Switzerland is among several countries developing large scale power-to-gas systems that leverage renewable energy to produce hydrogen, and that deploy existing natural gas pipelines and storage facilities to distribute hydrogen. Follow me on Twitter and Google+. Image: via Hypersolar. Get CleanTechnica’s 1st (completely free) electric car report → “Electric Cars: What Early Adopters & First Followers Want.” Come attend CleanTechnica’s 1st “Cleantech Revolution Tour” event → in Berlin, Germany, April 9–10. Keep up to date with all the hottest cleantech news by subscribing to our (free) cleantech newsletter, or keep an eye on sector-specific news by getting our (also free) solar energy newsletter, electric vehicle newsletter, or wind energy newsletter.
Home > Press > Made to order: Researchers discover a new form of crystalline matter: Experiments reveal a new type of imposed ordering of particles in dusty plasma Abstract: Dust is everywhere: under the bed, on the stairs and even inside of plasmas. A team of researchers from Auburn University, the University of Iowa and the University of California, San Diego, using the new Magnetized Dusty Plasma Experiment (MDPX), the first U.S. experiment of its kind, recently discovered a new form of crystalline-like matter in strongly magnetized dusty plasma. A feature of dusty plasmas is that under the proper conditions, usually at higher gas pressures, the dust particles can form self-organized, hexagonal structures--a configuration known as a "plasma crystal." The striking aspect of the newly discovered crystal structures is that the lattice (spacing between crystal particles) properties can be imposed arbitrarily by an external grid/mesh structure (Figure 1). These new made-to-order crystals can have any geometric pattern, making them distinct from the crystal lattices of ordinary solids and traditional plasma crystals, which are self-organized structures not imposed by external boundary conditions. In space, scientists observe large dust structures in star-forming regions such as planetary nebula. Small dust grains--the thickness of human hair or smaller--form amazing structures such as Saturn's rings and the long tails of comets. Most of these naturally-occurring dusty plasma systems have a very complex interaction between plasma, magnetic fields and these tiny, charged grains of dust. On the Earth, this same mixture of plasma, magnetic fields and charged dust grains, is often present in many industrial and research plasmas from semiconductor manufacturing to fusion experiments. In some cases, the dust is considered to be a source of contamination that needs to be controlled and safely removed from the plasma. But, if the properties of smaller (nanometer-scale) particles can be controlled and manipulated, they could prove to be an important tool in the future of plasma manufacturing. Ongoing studies on the MDPX show the ability to control the shape of these ordered structures and where they are suspended in the plasma (Figure 2). In the future, this discovery could lead to new approaches to trapping and controlling micro-particles in plasma and further efforts in designing their properties for both fundamental physics investigations and possible processing and industrial applications. For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.
A DNA-damaging protein in typhoid bacteria might keep infected animals alive and provide a safe haven for the microbes. Typhoid toxin, a protein produced by the typhoid fever-causing bacterium Salmonella enterica Typhi, tears DNA molecules apart. But the protein actually prolonged survival and reduced gut inflammation in mice infected with S. enterica, an international team of researchers reports April 7 in PLOS Pathogens. The deadly, mouse-infecting version of S. enterica doesn’t normally make the typhoid toxin. So the scientists modified mouse S. enterica with typhoid toxin genes from the human-infecting strain responsible for the high fever, headache and rash of typhoid fever. The team thought that typhoid toxin’s DNA slashing might cause tumors, but in mice fed the toxin-making S. enterica, no increased cancer risk appeared compared with mice given the toxin-free microbes. To the researchers’ surprise, though, more mice with the toxin survived 20 days of infection than did mice with the toxin-free strain. “When I first saw the data on the survival of the mice, I said, ‘No, we mixed up the strain,’ because we were expecting exactly the opposite,” says study coauthor Teresa Frisan, a cellular microbiologist at the Karolinska Institute in Stockholm. “We were chasing cancer, and we found biology of the toxin.” Mice infected with the typhoid toxin-making strain also had less intestinal inflammation after 10 days. Several genes linked to inflammation and immunity became less active after exposure to the toxin-making microbes, the team found. “Basically, what this toxin does is it modulates the host immune response,” Frisan says. This effect varied in other organs, with mouse livers showing increased inflammation regardless of the bacterial strain. Increased survival and decreased immunity may extend S. enterica’s stay within its host’s body. After six months, mice that survived infection with the typhoid toxin-free strain had no detectable S. enterica in their livers. But five out of six mice infected with the toxin-making strain still had substantial amounts of the bacteria in their livers. These results suggest that typhoid toxin promotes long-term, symptom-free infections, the researchers say. “Bacteria don’t want to kill their host; that makes no good sense,” says microbiologist Bradley Jones of the University of Iowa’s Carver College of Medicine in Iowa City. “You want to establish a low-level infection in your host, and then you just basically can grow … and you don’t have to go through this constant fighting for resources.” It appears that bacteria use typhoid toxin to ward off attacking immune cells, Jones says. Distinct differences exist between the mouse-infecting and human-infecting strains of S. enterica, even with the modifications made in the study, Jones says. Such differences could limit the clinical applicability of the results. But future studies could explore the possibility of disabling typhoid toxin to bolster an infected animal’s immune defenses, Jones says. Frisan says the scientists next hope to figure out exactly how typhoid toxin and its DNA-breaking action manipulate a host’s immune system. But given the toxin’s apparent ability to keep infected animals alive — and infectious bacteria around — the team suggests that the label of “toxin” may actually be undeserved.
News Article | November 18, 2015
Animals are constantly surprising us when it comes to science—just look at the dogs who can sniff out testicular cancer or the giant rats helping disarm land mines in Mozambique. The latest species to add to that list is the common pigeon (Columba livia). According to a study by a team of researchers in the US published in PLOS One, pigeons have an amazing ability to generalize patterns—something that could have serious future consequences in medical research. In a series of experiments, a team comprising researchers from UC Davis, the University of Iowa, and Emory University placed pigeons in front of images of benign and malignant breast cancer cells and rewarded them with food when they pressed a button correctly identifying each of them. Over time, the pigeons became so adept at recognising the cells’ properties that when the researchers changed the images to a never-before-seen set, they found the pigeons were able to generalize the patterns from one set to the other and distinguish benign cells from malignant cells. Example images of benign and malignant breast tissue slides at different levels of magnification. Image: Levenson et al. Over the course of approximately two weeks, they found they were able to train pigeons from 50 percent accuracy up to 85 percent—the same level of accuracy recorded in trained medical professionals. So what makes pigeons such natural pathologists? “There are predators in the wild that are very well-camouflaged, so it’s in the pigeon’s best interest to be able to detect the patterns that might reveal if there’s any danger in the bushes or not,” author Richard Levenson of UC Davis told Motherboard. The same faculties that allow them to detect predators allow the pigeons to recognise the difference between cancer cells. “Those problems [of evading predators] are mapped quite well to the problems of distinguishing between different kinds of medical images,” Levenson added. So what are the implications of these results? In the words of the authors, “Overall, our results suggest that pigeons can be used as suitable surrogates for human observers in certain medical image perception studies, thus avoiding the need to recruit, pay, and retain clinicians as subjects for relatively mundane tasks.” Does that mean a future of battery-farmed pigeon pathologists could be just around the corner? Levenson is hesitant to suggest anything quite so sensational just yet. After all, the role of radiologists is much more than just reading images for signs of cancer. For now, slightly smaller steps are on the radar. With regard to future research, Levenson said, “We are in discussion with some of my colleagues in artificial intelligence and pathology, and there are some harder data sets that I think we are going to attempt.” We might have to start being a bit nicer to our birdbrain friends.
Hobbits disappeared from their island home nearly 40,000 years earlier than previously thought, new evidence suggests. This revised timeline doesn’t erase uncertainty about the evolutionary origins of these controversial Indonesian hominids. Nor will the new evidence resolve a dispute about whether hobbits represent a new species, Homo floresiensis, or were small-bodied Homo sapiens. Hobbits vanished about 50,000 years ago at Liang Bua Cave on Flores, an island situated between Borneo and Australia’s northern coast, say archaeologist Thomas Sutikna of the University of Wollongong, Australia, and his colleagues. Cave sediment dating to about 12,000 years ago, which lies just above soil that yielded H. floresiensis remains, provided an initial estimate of when these diminutive hominids died out. But that sediment washed into the cave long after H. floresiensis was gone, covering much older, hobbit-bearing soil, the researchers report in the March 31 Nature. Using the initial age estimate, researchers had previously concluded that hobbits survived for tens of thousands of years after Homo sapiens passed through Indonesia and reached Australia around 50,000 years ago. It now appears that hobbits instead hit an evolutionary dead end around that time, Sutikna’s group says. The centerpiece of hobbit finds, a partial skeleton, comes from an individual who lived well before then, the scientists add. Measurements of the decay of radioactive elements in an arm bone from the partial skeleton indicate that the find dates to between 86,900 and 71,500 years ago. Until now, researchers suspected these bones were only about 18,000 years old. Based on the new dates, “there was possibly no overlap or interactions between H. floresiensis and H. sapiens on Flores,” says paleoanthropologist Richard Potts of the Smithsonian Institution in Washington, D.C. Hobbits disappeared before the earliest skeletal evidence of humans on Flores, says paleoanthropologist and study coauthor Matthew Tocheri of Lakehead University in Thunder Bay, Canada. H. sapiens bones date to around 11,000 years ago on the Indonesian island. That undermines a controversial argument that a partial hobbit skeleton comes from a human with a developmental disorder (SN: 11/18/06, p. 330), Tocheri says. Paleoanthropologist Russell Ciochon of the University of Iowa in Iowa City agrees. H. floresiensis probably descended from a large-bodied Asian Homo erectus group that reached Flores roughly 1 million years ago, he says. On islands, large-bodied mammals tend to become smaller, presumably in response to limited food sources and other factors. But in a joint e-mail to Science News, two researchers who regard hobbits as humans — and the partial hobbit skeleton as displaying signs of Down syndrome — stick to their guns. Regardless of the new dates from Liang Bua Cave, hobbit bones fall within the range of skeletal sizes and shapes observed in people today, assert Robert Eckhardt of Penn State and Maciej Henneberg of the University of Adelaide in Australia. H. sapiens could have reached Flores and nearby islands (SN: 2/6/16, p. 7) when Sutikna’s group says hobbits were alive, they claim. It’s not known whether humans or other Asian hominids, such as Denisovans (SN Online: 3/17/16), reached Flores more than 50,000 years ago at a time of lowered sea levels and possible drought on the island, Potts says. If they did, intruding species might have pushed an already reeling hobbit population to extinction. Liang Bua Cave excavations also suggest that other Flores animals, including vultures, giant marabou storks and an extinct elephant relative, vanished around the same time that the hobbits did. Annual excavations from 2007 through 2014 clarified how sediment accumulated in the cave. A thick soil deposit containing hobbit remains had substantially eroded before being covered by soil layers that washed into the cave starting around 20,000 years ago. Techniques for dating soil, rock, volcanic ash and bone indicated that hobbits’ skeletal remains ranged in age from 100,000 to 60,000 years ago. Stone tools probably made by hobbits dated to between around 190,000 and 50,000 years ago. Liang Bua Cave preserves a late slice of H. floresiensis life on an island probably reached by toolmaking hobbit ancestors around 1 million years ago (SN: 6/3/06, p. 341), Tocheri says. Researchers don’t know what happened during the roughly 800,000 years between hobbit ancestors’ arrival on Flores and hobbits’ last evolutionary stages. “If there was a book that chronicled the evolutionary history of H. floresiensis, we would have only a few tattered and torn pages with the rest missing,” Tocheri says. Editor’s Note: This story was updated April 4, 2016, to clarify the description of hobbits and the scientific discipline of one of the researchers.
But some animals carry more than two complete sets of the genome, referred to as polyploidy. Biologists have long wondered whether these extra chromosomes help or hinder those species. In a study involving multiple generations of a freshwater snail in New Zealand, researchers at the University of Iowa found that polyploidy appears to be neither an asset nor a drawback for females bearing offspring without the help of a male. Instead, it's the snails' sexuality that creates an advantage: Asexual females, the study found, grew twice as fast during the late juvenile phase and reached reproductive maturity 30 percent faster than female snails that mated with males. That in itself raises fundamental biological questions: If asexual females grow faster and bear children much more quickly than sexual females, what's the purpose of sex, and why is it the dominant method of reproduction in the animal world? "When we did the study, we thought polyploidy would be bad for asexuals, but we didn't find any evidence of that," says Maurine Neiman, associate professor of biology at the UI and corresponding author on the paper, published in the journal Ecology and Evolution. "This is making the role of sex even harder to explain." The mud snails, Potamopyrgus antipodarum, live in lakes and streams all over New Zealand. They were also discovered in Idaho in 1987 and have since spread to the Great Lakes and farther east to Chesapeake Bay, according to the U.S. Department of Agriculture, which classifies the animals as an invasive species. Sexual and asexual females are known to live in the same lakes in New Zealand, although they also exist separately in other lakes. Males will mate with either, but their genes are not passed on in encounters with asexual females. Those factors, and the snails' abundance, made them a good species in which to test the effects of polyploidy. The UI team compared sexually reproductive female snails with only two copies of their genome to asexual females carrying three and four copies. Together, they produced enough generations to occupy 1,500 cups—one cup per snail. "When we began, we thought the project would take six to nine months," says Katelyn Larkin, who earned her bachelor's and master's degrees in biology at the UI and has worked in Neiman's lab since she was a sophomore. "Instead, it took more than three years. We learned that these snails grow at a snail's pace." The asexual females, regardless of the number of genomic copies they possessed, grew faster and reached reproductive maturity quicker than the sexual females, the researchers discovered. In human terms, it'd be as if the asexual females could produce children at 13 years of age, whereas the sexual females wouldn't reach reproductive age until age 18. Couple that with the fact that asexual females produce only female offspring, and you wonder why sexual female snails still exist. "It's not only that (the asexuals) are not making males. The asexual daughters are growing up faster too," Neiman notes. Before her study, Neiman thought the asexual females would bear extra costs for each additional genome because they would be chock full of metabolically expensive ingredients like RNA and proteins. Such is the case with plants, like wheat. But there was no difference in growth rate, shell length, or time to reproductive maturity between asexual females with three genomic copies and those with four, ruling out that theory. Instead, the surprise lay in the fact the asexual females didn't seem to pay any price whatsoever for having those extra genomes. In fact, there was no discernible disadvantage at all. So, why do sexual female snails exist, and how do they survive when they're co-existing and competing with asexual females? The answer may lie in part to a parasitic worm that preys upon the snails. The asexual females are more vulnerable because their offspring's genomes are exact replicas of their own, making them easier to target and wipe out. The sexual females, because they mate, inherit a separate, distinct genomic set that diversifies the gene pool and thus makes them better able to withstand parasitic attacks. Still, sexual females have been found alongside asexuals in lakes without the parasitic worms, which muddies the whole idea that genetic diversity is the sole reason why sexual snails persist. Neiman seems to like it that way. "You could argue that our genome is the most important thing we have, yet we don't know why humans have two copies when a lot of organisms do fine with one, or three, or more," she says. "This research speaks to that question." Explore further: Parasites keep things sexy in 'hotspots' More information: Katelyn Larkin et al. Effects of polyploidy and reproductive mode on life history trait expression, Ecology and Evolution (2016). DOI: 10.1002/ece3.1934
News Article | April 28, 2016
When you think of a neuron, imagine a tree. A healthy brain cell indeed looks like a tree with a full canopy. There's a trunk, which is the cell's nucleus; there's a root system, embodied in a single axon; and there are the branches, called dendrites. Neurons in your brain pass signals from one to another like they're playing an elaborate, lightning-quick game of telephone, using axons as the transmitters and dendrites as the receivers. Those signals originate in the brain and are passed throughout the body, culminating in simple actions, such as wiggling a toe, to more complex instructions, such as following through on a thought. Just as you can judge a healthy tree by its canopy, so too can scientists judge a healthy neuron by its dendritic branches. But it had been unclear what causes dendrites to grow, and where those instructions to grow come from. Biologists at the University of Iowa have determined a group of genes associated with neurons help regulate dendrites' growth. But there's a catch: These genes, called gamma-protocadherins, must be an exact match for each neuron for the cells to correctly grow dendrites. The findings may offer new insight into what causes aggressive or stunted dendrite growth in neurons, which could help explain the biological reasons for some mental-health diseases, as well as help researchers better understand brain development in babies born prematurely. "Disrupted dendrite arborization is seen in the brains of people with autism and schizophrenia, so processes like the one we have uncovered here may have relevance to human disorders," said Joshua Weiner, a molecular biologist at the UI and corresponding author on the paper, published online this month in the journal Cell Reports. Gamma-protocadherins are called "adhesion molecules" because they stick out from a cell's membrane to bind and hold cells together. The researchers learned about their role by giving a developing brain cell in a mouse the same gamma-protocadherin as in surrounding cells. When they did, the cells grew longer, more complex dendrites. But when the researchers outfitted a mouse neuron with a different gamma-protocadherin than the cells around it, dendritic growth was stunted. The human brain is filled with neurons. Scientists think adults have 100 billion brain cells, each in close proximity to others and all seeking to make contact through their axons and dendrites. The denser a neuron's dendritic network, the more apt a cell is to be in touch with another and aid in passing signals. Gamma-protocadherins act like molecular Velcro, binding neurons together and instructing them to grow their dendrites. Weiner and his team figured out their role when they observed paltry dendritic growth in mouse brain cells where the gamma-protocadherins had been silenced. The researchers went further in the new study. Using mice, they expressed the same type of gamma-protocadherin (labeled either as A1 or C3) in neurons in the cerebral cortex, a region of the brain that processes language and information. After five weeks, the neurons had sizeable dendritic networks, indicative of a healthy, normally functioning brain. Likewise, when they turned on a gamma-protocadherin gene in a neuron different from the gamma-protocadherin gene with the cells surrounding it, the mice had limited dendrite growth after the same time period. That's important because human neurons carry up to six gamma-protocadherins, meaning there are many combinations potentially in play. Yet, it seems the "grow your dendrite" signal only happens when neurons carrying the the same gamma-protocadherin gene pair up. "The neurons actually care who they match with," said Weiner, associate professor in the Department of Biology, part of the College of Liberal Arts and Sciences. "It takes what we knew from biochemical studies in a dish and shows that protocadherins really mediate these matching interactions in the developing brain." The team reports that star-looking cells called astrocytes also play a role in neurons' dendrite development. Astrocytes are glial (Greek for "glue") cells that help to bridge the gap between neurons and speed signals along. When the molecular binding between an astrocyte and neurons is an exact match, the neurons grow fully formed dendrites, the researchers report. "Our data indicate that g-Pcdhs (gamma-protocadherins) act locally to promote dendrite arborization via homophilic matching and confirm that connectivity in vivo depends on molecular interactions between neurons and between neurons and astrocytes," the authors write.
Dozens of scientists and others with expertise in climate change today called for U.S. presidential candidates to spell out how they intend to make the U.S. the world leader in clean energy. “The global transformation of our energy system away from fossil fuels is both a moral imperative, grounded in science, and one of the greatest economic opportunities of our time,” says a letter to the presidential candidates. The missive, organized by the Union of Concerned Scientists (UCS), an advocacy group, is signed by 74 climate experts, including former members of the Intergovernmental Panel on Climate Change and a former energy secretary. The letter urges candidates to “meet and exceed” the short-term pledge President Barack Obama has made: that the U.S. will reduce its greenhouse gas emissions 26–28% below 2005 levels by 2025. Obama made the promise in the run-up to negotiations now under way in Paris on a new global climate change treaty. “It’s imperative for the next President to build on the commitments the U.S. is making in Paris,” Peter Frumhoff, director of science and policy at UCS, told reporters at the Paris meeting. The letter, he said, is designed to “build demand among voters to expect all candidates to have clear and convincing answers about their commitments to a clean energy future.” The issue of climate change has received little attention on the presidential campaign trail thus far. A few Republican candidates, including top-polling Donald Trump, have dismissed the notion of human-caused climate change. Others seeking the Oval Office, including Democratic front-runner Hillary Clinton, accept the science about global warming, but they differ on whether or how to address it. “We need a president who will make good decisions and choices based on the available science,” said one of the letter’s signers, Katherine Hayhoe, director of the Climate Science Center at Texas Tech University. “There is certainly plenty of debate over what those solutions could look like, but the debate should not focus on whether there’s a real problem or not.” Clean energy technologies are already advancing “in leaps and bounds,” she said. Other signers of the letter include former Energy Secretary Steven Chu, a Stanford University physics professor; Scott C. Doney, chair of the marine chemistry & geochemistry department at the Woods Hole Oceanographic Institution; and Jerald L. Schnoor, professor of environmental engineering at the University of Iowa.
News Article | November 18, 2015
If pigeons went to medical school and specialized in pathology or radiology, they'd be pretty good at distinguishing digitized microscope slides and mammograms of normal from cancerous breast tissue, according to a new study from the University of Iowa and the University of California, Davis.
News Article | October 29, 2013
The last time we heard from TC50 alum Jibe, it locked up a $10 million Series B from the likes of Longworth Venture Partners (which led the round), Polaris Partners, Lerer Ventures, DFJ Gotham, and Thrive Capital in a bid to make it easier to apply for jobs from smartphones. This time around, though, Jibe has more money to expand its operations but without having to offer up any equity in exchange — the team recently announced that it’s secured a $4 million credit facility from Silicon Valley Bank as it prepares to flesh out its backend services for enterprise partners looking to hire the right people. “We’re helping to process hundreds of thousands of applications now,” CEO Joe Essenfeld told me. “But these companies really want to rely on data to see how the application and hiring process differs for different kinds of jobs.” Speaking of hiring, he also noted the Jibe team isn’t complete just yet and that hiring would continue as the company prepares to move into a new office in Greenwich Village. As it happens, Jibe has already put part of its new plan into motion. Earlier this month it rolled out a suite of backend tools meant for recruiters. If you thought applying for a job was tough, think about what it must be like for the poor recruiter/HR person stuck trying to sift through that pile of applications. Essenfeld said that three (sadly unnamed) Fortune 1000 companies jumped on the bandwagon when the startup released its recruiter analytics tools, which lets business insiders see where its applicants are coming from, how they stumbled upon the job opening, and how much time they spend on the application. Perhaps most important is the ability to pinpoint the moment those would-be employees give up on filling out their applications, which should give those companies some insight into how to smooth out the onboarding process.
News Article | June 30, 2016
The Juno spacecraft will become the seventh robotic vehicle to visit Jupiter when the observatory speeds past the planet on July 4. This vehicle, packed with a bevy of scientific instruments, will join a short list of six other space vehicles that have visited the largest planet in the solar system over the last 45 years. Pioneer 10 was launched to the Jovian system in 1972, reaching its destination in December 1973. The NASA mission measured concentrations of hydrogen and helium gas in the atmosphere of the giant world. The vehicle discovered the powerful magnetosphere surrounding the globe, and was the first spacecraft to endure the rigors of Jupiter's powerful radiation belt. The year 1979 saw a pair of revolutionary observatories fly past Jupiter — Voyager One and Two. These vehicles, managed by NASA, soared past the gas giant in March and July of that year. As the observatories soared past the world, a look at the dark side of Jupiter revealed massive lightning strikes taking place across the face of the globe. The Voyager observatories were able to photograph the surfaces of many of Jupiter's moons, allowing researchers to develop maps of the satellites for the first time. The innermost moon of Jupiter, Io, was found to be geologically active, with volcanoes erupting on the surface. Due to advances in technology since the Pioneer visit, the Voyager mission was able to return far more data than its predecessor. Both vehicles are now traveling out of the solar system, to interstellar space. "The prime mission science payload consisted of 10 instruments (11 investigations including radio science). Only five investigator teams are still supported, though data are collected for two additional instruments. With the exception of the Voyager 1 PLS instrument, all of the above are working well and are capable of continuing operations in the expected environment," Jet Propulsion Laboratory reports. Galileo became the first spacecraft to orbit Jupiter, after being launched to that world in 1989. Since its arrival in the Jovian system, the observatory has carried out careful examinations of the gas giant, as well as its dozens of attendant moons. The vehicle was named in honor of Galileo Galilei, the Italian astronomer who carried out the first telescopic observations of the system during the early 17th century. Launched in October 1990, the Ulysses spacecraft passed by Jupiter on its way toward a polar orbit over the sun. As the vehicle swung through the massive gravitational well of Jupiter, the observatory found the solar wind affects the magnetosphere of the world to a much greater extent than astronomers had predicted. On June 30, 2016, Juno passed into the magnetic field of Jupiter, marking the spacecraft's imminent arrival at the giant world. "If Jupiter's magnetosphere glowed in visible light, it would be twice the size of the full moon as seen from Earth," said William Kurth of the University of Iowa. Juno promises to answer a number of questions investigators are currently asking themselves about the largest planetary body in the solar system. If history is any guide, discoveries by the mission will reveal additional questions. © 2016 Tech Times, All rights reserved. Do not reproduce without permission.
Nabhan C.,University of Chicago |
Zhou X.,Biometrics |
Day B.-M.,Genentech |
Dawson K.,Genentech |
And 5 more authors.
American Journal of Hematology | Year: 2016
We aimed to comprehensively study sex differences in disease and patients' characteristics, treatment and outcomes in patients with follicular lymphoma (FL) in the United States (USA) utilizing the National LymphoCare Study registry (2004–2014). Among evaluable males (n = 1277) and females (n = 1375) with FL, females less commonly received anthracyclines and were more likely to receive rituximab monotherapy. Overall response rates were comparable between sex groups. With a median follow-up of 8.1 years, male sex emerged as an adverse factor for PFS (HR, 0.84, 95% CI, 0.72–0.97). Lymphoma-related mortality (HR, 0.46; 0.23–0.93) and overall survival (HR, 0.63; 0.41–0.97) favored females aged ≤60 years. There are subtle differences in outcomes between male and female FL patients diagnosed and treated in the contemporary era. These data represent the largest prospective analysis of FL patients in the USA based on sex and can aid design of clinical trials for this disease. Am. J. Hematol. 91:770–775, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.
Figure 1: [Left] Typical plasma crystal with a self-ordered, hexagonal arrangement of dust particles indicated by the bright white spots. [Middle] Made to order square pattern formed in an imposed dust crystalline-like structure. [Right] A typical dusty plasma illuminated by a green laser in the MDPX experiment at Auburn University. Credit: Max Planck Institute Dust is everywhere: under the bed, on the stairs and even inside of plasmas. A team of researchers from Auburn University, the University of Iowa and the University of California, San Diego, using the new Magnetized Dusty Plasma Experiment (MDPX), the first U.S. experiment of its kind, recently discovered a new form of crystalline-like matter in strongly magnetized dusty plasma. A feature of dusty plasmas is that under the proper conditions, usually at higher gas pressures, the dust particles can form self-organized, hexagonal structures—a configuration known as a "plasma crystal." The striking aspect of the newly discovered crystal structures is that the lattice (spacing between crystal particles) properties can be imposed arbitrarily by an external grid/mesh structure (Figure 1). These new made-to-order crystals can have any geometric pattern, making them distinct from the crystal lattices of ordinary solids and traditional plasma crystals, which are self-organized structures not imposed by external boundary conditions. In space, scientists observe large dust structures in star-forming regions such as planetary nebula. Small dust grains—the thickness of human hair or smaller—form amazing structures such as Saturn's rings and the long tails of comets. Most of these naturally-occurring dusty plasma systems have a very complex interaction between plasma, magnetic fields and these tiny, charged grains of dust. On the Earth, this same mixture of plasma, magnetic fields and charged dust grains, is often present in many industrial and research plasmas from semiconductor manufacturing to fusion experiments. In some cases, the dust is considered to be a source of contamination that needs to be controlled and safely removed from the plasma. But, if the properties of smaller (nanometer-scale) particles can be controlled and manipulated, they could prove to be an important tool in the future of plasma manufacturing. Ongoing studies on the MDPX show the ability to control the shape of these ordered structures and where they are suspended in the plasma (Figure 2). In the future, this discovery could lead to new approaches to trapping and controlling micro-particles in plasma and further efforts in designing their properties for both fundamental physics investigations and possible processing and industrial applications. Explore further: The sound in Saturn's rings: Physicists explain nonlinear dust acoustic waves in dusty plasmas More information: Abstracts: JP12.00034 Analysis of particle trajectories in a simulated, magnetized dusty plasma in a radially-increasing electric field NI2.00001 Summary of initial results from the Magnetized Dusty Plasma Experiment (MDPX) device UP12.00060 Imposed, ordered dust structures and other plasma features in a strongly magnetized plasma
In a first-of-its-kind study, the American Watershed Initiative gave the Mississippi River basin, the fourth largest in the world, its first report card – and it probably won’t be going up on the fridge. After five years of research, meetings, and symposiums — which brought together 700 people representing 400 organizations to analyze the basin’s water supply, transportation, flood control, economy, recreation, and ecosystem health – the Initiative gave the Mississippi River watershed an overall grade of D+, concluding that increased funding is needed to better manage the watershed. “Unless we as a population get behind supporting improvements behind the Mississippi River system, we’ll never get the political support for it and we’ll never be able to make changes,” said Larry Weber of the Iowa Flood Center at the University of Iowa. The Mississippi River watershed encompasses thousands of miles of waterways in 31 states and two Canadian provinces – stretching from Montana to Pennsylvania, Minnesota to Louisiana. They all ultimately drain into the Mississippi River and the Gulf of Mexico. According to the report, the system is used to produce more than half of the United States’ goods and services and generates a fourth of the country’s hydropower. And here’s where it fared particularly badly: Transportation. Of the six areas analyzed, transportation was given the lowest individual grade: D-. Heath Kelsey of the University of Maryland, the Initiative’s project lead, said that between two and three percent of the watershed’s locks – which regulate water levels to help ships travel along rivers – are in disrepair. “Two to three percent of the infrastructure in failing or near-failing condition is a big deal,” Kelsey said. “Because the system is really connected. If one of the locks fail, it could have a cascading effect on the [rivers’] transportation systems.” $54 billion in agricultural products are transported through the basin’s waterways annually, according to the report, encompassing 92 percent of the United States’ farm exports. Water quality. The overall quality of the water supply also received a low grade. The Initiative identified the growing dead zone in the Gulf of Mexico as a watershed-wide problem that needs to be addressed. Excess nutrients, particularly nitrates, draining into the Gulf deplete the water of oxygen, damaging the ecosystem. “It’s pretty obvious that the [dead zone] has not decreased over the years,” said Nancy Rabalais, Executive Director of the Louisiana Universities Marine Consortium. “The low oxygen is getting worse in severity and duration. So there is very strong evidence that the system, especially since the [1970s], has been exposed to low oxygen conditions probably each summer.” Tackling the Gulf’s dead zone will begin upstream with plans to reduce the amount of nutrients draining into the basin’s waterways. “The nitrate concentration loads started going up in the [1950s], coinciding with fertilizer use in the watershed,” Rabalais said. “The high nutrients that are affecting the Gulf area are also affecting water quality in the watershed. It’s not just a Gulf problem, it’s a watershed problem.” The Ohio and Tennessee River basin – one of the six sub-basins that make up the Mississippi River watershed – received one of the lowest individual grades for water quality. Forbes Walker, a soil scientist at the University of Tennessee, said erosion and soil discharge off of agricultural land are closely tied to the amount of nutrients that particular region dumps into the Gulf. “If we can control soil erosion, we can make great strides in reducing the loads that are going into the rivers and thereby into the Gulf,” Walker said. “We don’t consider ourselves to be one of the big [contributors], but that’s not to say we shouldn’t address it.” Flood Control. On flood control, which also received a low grade, Kelsey said the Initiative found that the Mississippi basin’s levees are in poor condition, and the population of people living in floodplains is only increasing. “Those things together add up to not such great news,” Kelsey said. Unless measures are taken to prevent or better prepare communities for levee breaches, floods like the one that hit Cedar Rapids, Iowa in 2008 could become more frequent. In June of that year, heavy rains caused the swollen Cedar River to burst through the city’s levees, flooding 14 percent of the city and prompting the evacuation of some 24,000 people. “Each decade as we add more data, we start realizing that these levees in some places are underbuilt,” Larry Weber said. “And we have to continue to fortify those levees – and that’s expensive.” America’s Watershed Initiative, which unveiled the report card in St. Louis on Wednesday, called for increased funding to tackle the watershed’s problems – to the tune of $1 billion annually. “We really need to increase the investment in the Mississippi River Basin,” the Initiative’s Executive Director Jordy Jordahl said. “From local, state, federal, and private funds.”