Maps of magnesium/silicon (left) and thermal neutron absorption (right) across Mercury's surface (red indicates high values, blue low). These maps, together with maps of other elemental abundances, reveal the presence of distinct geochemical terranes. Volcanic smooth plains deposits are outlined in white.

Two new papers from members of the MESSENGER Science Team provide global-scale maps of Mercury's surface chemistry that reveal previously unrecognized geochemical terranes -- large regions that have compositions distinct from their surroundings. The presence of these large terranes has important implications for the history of the planet.

The MESSENGER mission was designed to answer several key scientific questions, including the nature of Mercury's geological history. Remote sensing of the surface's chemical composition has a strong bearing on this and other questions. Since MESSENGER was inserted into orbit about Mercury in March 2011, data from the spacecraft's X-Ray Spectrometer (XRS) and Gamma-Ray Spectrometer (GRS) have provided information on the concentrations of potassium, thorium, uranium, sodium, chlorine, and silicon, as well as ratios relative to silicon of magnesium, aluminum, sulfur, calcium, and iron.

Until now, however, geochemical maps for some of these elements and ratios have been limited to one hemisphere and have had poor spatial resolution. In "Evidence for geochemical terranes on Mercury: Global mapping of major elements with MESSENGER's X-Ray Spectrometer," published this week in Earth and Planetary Science Letters, the authors used a novel methodology to produce global maps of the magnesium/silicon and aluminum/silicon abundance ratios across Mercury's surface from data acquired by MESSENGER's XRS.

These are the first global geochemical maps of Mercury, and the first maps of global extent for any planetary body acquired via the technique of X-ray fluorescence, by which X-rays emitted from the Sun's atmosphere allow the planet's surface composition to be examined. The global magnesium and aluminum maps were paired with less spatially complete maps of sulfur/silicon, calcium/silicon, and iron/silicon, as well as other MESSENGER datasets, to study the geochemical characteristics of Mercury's surface and to investigate the evolution of the planet's thin silicate shell.

The most obvious of Mercury's geochemical terranes is a large feature, spanning more than 5 million square kilometers. This terrane "exhibits the highest observed magnesium/silicon, sulfur/silicon, and calcium/silicon ratios, as well as some of the lowest aluminum/silicon ratios on the planet's surface," writes Shoshana Weider, a planetary geologist and Visiting Scientist at the Carnegie Institution. Weider and colleagues suggest that this "high-magnesium region" could be the site of an ancient impact basin. By this interpretation, the distinctive chemical signature of the region reflects a substantial contribution from mantle material that was exposed during a large impact event.

A second paper, "Geochemical terranes of Mercury's northern hemisphere as revealed by MESSENGER neutron measurements," now available online in Icarus, presents the first maps of the absorption of low-energy ("thermal") neutrons across Mercury's surface. The data used in this second study were obtained with the GRS anti-coincidence shield, which is sensitive to neutron emissions from the surface of Mercury.

"From these maps we may infer the distribution of thermal-neutron-absorbing elements across the planet, including iron, chlorine, and sodium," writes lead author Patrick Peplowski of The Johns Hopkins University Applied Physics Laboratory. "This information has been combined with other MESSENGER geochemical measurements, including the new XRS measurements, to identify and map four distinct geochemical terranes on Mercury."

According to Peplowski, the results indicate that the smooth plains interior to the Caloris basin, Mercury's largest well-preserved impact basin, have an elemental composition that is distinct from other volcanic plains units, suggesting that the parental magmas were partial melts from a chemically distinct portion of Mercury's mantle. Mercury's high-magnesium region, first recognized from the XRS measurements, also contains high concentrations of unidentified neutron-absorbing elements.

"Earlier MESSENGER data have shown that Mercury's surface was pervasively shaped by volcanic activity," notes Peplowski. "The magmas erupted long ago were derived from the partial melting of Mercury's mantle. The differences in composition that we are observing among geochemical terranes indicate that Mercury has a chemically heterogeneous mantle."

"The consistency of the new XRS and GRS maps provides a new dimension to our view of Mercury's surface," Weider adds. "The terranes we observe had not previously been identified on the basis of spectral reflectance or geological mapping."

"The crust we see on Mercury was largely formed more than three billion years ago," says Carnegie's Larry Nittler, Deputy Principal Investigator of the mission and co-author of both studies. "The remarkable chemical variability revealed by MESSENGER observations will provide critical constraints on future efforts to model and understand Mercury's bulk composition and the ancient geological processes that shaped the planet's mantle and crust."

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Saturn moon's ocean may harbor hydrothermal activity, spacecraft data suggest

This cutaway view of Saturn's moon Enceladus is an artist's rendering that depicts possible hydrothermal activity that may be taking place on and under the seafloor of the moon's subsurface ocean, based on recently published results from NASA's Cassini mission.

NASA's Cassini spacecraft has provided scientists the first clear evidence that Saturn's moon Enceladus exhibits signs of present-day hydrothermal activity which may resemble that seen in the deep oceans on Earth. The implications of such activity on a world other than our planet open up unprecedented scientific possibilities.

"These findings add to the possibility that Enceladus, which contains a subsurface ocean and displays remarkable geologic activity, could contain environments suitable for living organisms," said John Grunsfeld, astronaut and associate administrator of NASA's Science Mission Directorate in Washington. "The locations in our solar system where extreme environments occur in which life might exist may bring us closer to answering the question: are we alone in the universe."

Hydrothermal activity occurs when seawater infiltrates and reacts with a rocky crust and emerges as a heated, mineral-laden solution, a natural occurrence in Earth's oceans. According to two science papers, the results are the first clear indications an icy moon may have similar ongoing active processes.

The first paper, published this week in the journal Nature, relates to microscopic grains of rock detected by Cassini in the Saturn system. An extensive, four-year analysis of data from the spacecraft, computer simulations and laboratory experiments led researchers to the conclusion the tiny grains most likely form when hot water containing dissolved minerals from the moon's rocky interior travels upward, coming into contact with cooler water. Temperatures required for the interactions that produce the tiny rock grains would be at least 194 degrees Fahrenheit (90 degrees Celsius).

"It's very exciting that we can use these tiny grains of rock, spewed into space by geysers, to tell us about conditions on -- and beneath -- the ocean floor of an icy moon," said the paper's lead author Sean Hsu, a postdoctoral researcher at the University of Colorado at Boulder.

Cassini's cosmic dust analyzer (CDA) instrument repeatedly detected miniscule rock particles rich in silicon, even before Cassini entered Saturn's orbit in 2004. By process of elimination, the CDA team concluded these particles must be grains of silica, which is found in sand and the mineral quartz on Earth. The consistent size of the grains observed by Cassini, the largest of which were 6 to 9 nanometers, was the clue that told the researchers a specific process likely was responsible.

On Earth, the most common way to form silica grains of this size is hydrothermal activity under a specific range of conditions; namely, when slightly alkaline and salty water that is super-saturated with silica undergoes a big drop in temperature.

"We methodically searched for alternate explanations for the nanosilica grains, but every new result pointed to a single, most likely origin," said co-author Frank Postberg, a Cassini CDA team scientist at Heidelberg University in Germany.

Hsu and Postberg worked closely with colleagues at the University of Tokyo who performed the detailed laboratory experiments that validated the hydrothermal activity hypothesis. The Japanese team, led by Yasuhito Sekine, verified the conditions under which silica grains form at the same size Cassini detected. The researchers think these conditions may exist on the seafloor of Enceladus, where hot water from the interior meets the relatively cold water at the ocean bottom.

The extremely small size of the silica particles also suggests they travel upward relatively quickly from their hydrothermal origin to the near-surface sources of the moon's geysers. From seafloor to outer space, a distance of about 30 miles (50 kilometers), the grains spend a few months to a few years in transit, otherwise they would grow much larger.

The authors point out that Cassini's gravity measurements suggest Enceladus' rocky core is quite porous, which would allow water from the ocean to percolate into the interior. This would provide a huge surface area where rock and water could interact.

The second paper, recently published in Geophysical Research Letters, suggests hydrothermal activity as one of two likely sources of methane in the plume of gas and ice particles that erupts from the south polar region of Enceladus. The finding is the result of extensive modeling to address why methane, as previously sampled by Cassini, is curiously abundant in the plume.

The team found that, at the high pressures expected in the moon's ocean, icy materials called clathrates could form that imprison methane molecules within a crystal structure of water ice. Their models indicate that this process is so efficient at depleting the ocean of methane that the researchers still needed an explanation for its abundance in the plume.

In one scenario, hydrothermal processes super-saturate the ocean with methane. This could occur if methane is produced faster than it is converted into clathrates. A second possibility is that methane clathrates from the ocean are dragged along into the erupting plumes and release their methane as they rise, like bubbles forming in a popped bottle of champagne.

The authors agree both scenarios are likely occurring to some degree, but they note that the presence of nanosilica grains, as documented by the other paper, favors the hydrothermal scenario.

"We didn't expect that our study of clathrates in the Enceladus ocean would lead us to the idea that methane is actively being produced by hydrothermal processes," said lead author Alexis Bouquet, a graduate student at the University of Texas at San Antonio. Bouquet worked with co-author Hunter Waite, who leads the Cassini Ion and Neutral Mass Spectrometer (INMS) team at Southwest Research Institute in San Antonio.

Cassini first revealed active geological processes on Enceladus in 2005 with evidence of an icy spray issuing from the moon's south polar region and higher-than-expected temperatures in the icy surface there. With its powerful suite of complementary science instruments, the mission soon revealed a towering plume of water ice and vapor, salts and organic materials that issues from relatively warm fractures on the wrinkled surface. Gravity science results published in 2014 strongly suggested the presence of a 6-mile- (10-kilometer-) deep ocean beneath an ice shell about 19 to 25 miles (30 to 40 kilometers) thick.

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Engineers create chameleon-like artificial 'skin' that shifts color on demand

Developed by engineers from the University of California at Berkeley, this chameleon-like artificial "skin" changes color as a minute amount of force is applied.

Borrowing a trick from nature, engineers from the University of California at Berkeley have created an incredibly thin, chameleon-like material that can be made to change color -- on demand -- by simply applying a minute amount of force.

This new material-of-many-colors offers intriguing possibilities for an entirely new class of display technologies, color-shifting camouflage, and sensors that can detect otherwise imperceptible defects in buildings, bridges, and aircraft.

"This is the first time anybody has made a flexible chameleon-like skin that can change color simply by flexing it," said Connie J. Chang-Hasnain, a member of the Berkeley team and co-author on a paper published today in Optica, The Optical Society's (OSA) new high-impact journal.

By precisely etching tiny features -- smaller than a wavelength of light -- onto a silicon film one thousand times thinner than a human hair, the researchers were able to select the range of colors the material would reflect, depending on how it was flexed and bent.

A Material that's a Horse of a Different Color

The colors we typically see in paints, fabrics, and other natural substances occur when white, broad spectrum light strikes their surfaces. The unique chemical composition of each surface then absorbs various bands, or wavelengths of light. Those that aren't absorbed are reflected back, with shorter wavelengths giving objects a blue hue and longer wavelengths appearing redder and the entire rainbow of possible combinations in between. Changing the color of a surface, such as the leaves on the trees in autumn, requires a change in chemical make-up.

Recently, engineers and scientists have been exploring another approach, one that would create designer colors without the use of chemical dyes and pigments. Rather than controlling the chemical composition of a material, it's possible to control the surface features on the tiniest of scales so they interact and reflect particular wavelengths of light. This type of "structural color" is much less common in nature, but is used by some butterflies and beetles to create a particularly iridescent display of color.

Controlling light with structures rather than traditional optics is not new. In astronomy, for example, evenly spaced slits known as diffraction gratings are routinely used to direct light and spread it into its component colors. Efforts to control color with this technique, however, have proved impractical because the optical losses are simply too great.

The authors of the Optica paper applied a similar principle, though with a radically different design, to achieve the color control they were looking for. In place of slits cut into a film they instead etched rows of ridges onto a single, thin layer of silicon. Rather than spreading the light into a complete rainbow, however, these ridges -- or bars -- reflect a very specific wavelength of light. By "tuning" the spaces between the bars, it's possible to select the specific color to be reflected. Unlike the slits in a diffraction grating, however, the silicon bars were extremely efficient and readily reflected the frequency of light they were tuned to.

Flexibility Is the Key to Control

Since the spacing, or period, of the bars is the key to controlling the color they reflect, the researchers realized it would be possible to subtly shift the period -- and therefore the color -- by flexing or bending the material.

"If you have a surface with very precise structures, spaced so they can interact with a specific wavelength of light, you can change its properties and how it interacts with light by changing its dimensions," said Chang-Hasnain.

Earlier efforts to develop a flexible, color shifting surface fell short on a number of fronts. Metallic surfaces, which are easy to etch, were inefficient, reflecting only a portion of the light they received. Other surfaces were too thick, limiting their applications, or too rigid, preventing them from being flexed with sufficient control.

The Berkeley researchers were able to overcome both these hurdles by forming their grating bars using a semiconductor layer of silicon approximately 120 nanometers thick. Its flexibility was imparted by embedding the silicon bars into a flexible layer of silicone. As the silicone was bent or flexed, the period of the grating spacings responded in kind.

The semiconductor material also allowed the team to create a skin that was incredibly thin, perfectly flat, and easy to manufacture with the desired surface properties. This produces materials that reflect precise and very pure colors and that are highly efficient, reflecting up to 83 percent of the incoming light.

Their initial design, subjected to a change in period of a mere 25 nanometers, created brilliant colors that could be shifted from green to yellow, orange, and red -- across a 39-nanometer range of wavelengths. Future designs, the researchers believe, could cover a wider range of colors and reflect light with even greater efficiency.

Chameleon Skin with Multiple Applications

For this demonstration, the researchers created a one-centimeter square layer of color-shifting silicon. Future developments would be needed to create a material large enough for commercial applications.

"The next step is to make this larger-scale and there are facilities already that could do so," said Chang-Hasnain. "At that point, we hope to be able to find applications in entertainment, security, and monitoring."

For consumers, this chameleon material could be used in a new class of display technologies, adding brilliant color presentations to outdoor entertainment venues. It also may be possible to create an active camouflage on the exterior of vehicles that would change color to better match the surrounding environment.

More day-to-day applications could include sensors that would change color to indicate that structural fatigue was stressing critical components on bridges, buildings, or the wings of airplanes.

"This is the first time anyone has achieved such a broad range of color on a one-layer, thin and flexible surface," concluded Change-Hasnain. "I think it's extremely cool."

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Underground ocean on Jupiter's largest moon, Ganymede

Observation of Aurorae on Ganymede. NASA's Hubble Space Telescope observed a pair of auroral belts encircling the Jovian moon Ganymede. The belts were observed in ultraviolet light by the Space Telescope Imaging Spectrograph and are colored blue in this illustration. They are overlaid on a visible-light image of Ganymede taken by NASA's Galileo orbiter. The locations of the glowing aurorae are determined by the moon's magnetic field, and therefore provide a probe of the moon's interior, where the magnetic field is generated. The amount of rocking of the magnetic field, caused by its interaction with Jupiter's own immense magnetosphere, provides evidence that the moon has a subsurface ocean of saline water.

NASA's Hubble Space Telescope has the best evidence yet for an underground saltwater ocean on Ganymede, Jupiter's largest moon. The subterranean ocean is thought to have more water than all the water on Earth's surface.

Identifying liquid water is crucial in the search for habitable worlds beyond Earth and for the search for life, as we know it.

"This discovery marks a significant milestone, highlighting what only Hubble can accomplish," said John Grunsfeld, assistant administrator of NASA's Science Mission Directorate at NASA Headquarters, Washington, D.C. "In its 25 years in orbit, Hubble has made many scientific discoveries in our own solar system. A deep ocean under the icy crust of Ganymede opens up further exciting possibilities for life beyond Earth."

Ganymede is the largest moon in our solar system and the only moon with its own magnetic field. The magnetic field causes aurorae, which are ribbons of glowing, hot electrified gas, in regions circling the north and south poles of the moon. Because Ganymede is close to Jupiter, it is also embedded in Jupiter's magnetic field. When Jupiter's magnetic field changes, the aurorae on Ganymede also change, "rocking" back and forth.

By watching the rocking motion of the two aurorae, scientists were able to determine that a large amount of saltwater exists beneath Ganymede's crust, affecting its magnetic field.

A team of scientists led by Joachim Saur of the University of Cologne in Germany came up with the idea of using Hubble to learn more about the inside of the moon.

"I was always brainstorming how we could use a telescope in other ways," said Saur. "Is there a way you could use a telescope to look inside a planetary body? Then I thought, the aurorae! Because aurorae are controlled by the magnetic field, if you observe the aurorae in an appropriate way, you learn something about the magnetic field. If you know the magnetic field, then you know something about the moon's interior."

If a saltwater ocean were present, Jupiter's magnetic field would create a secondary magnetic field in the ocean that would counter Jupiter's field. This "magnetic friction" would suppress the rocking of the aurorae. This ocean fights Jupiter's magnetic field so strongly that it reduces the rocking of the aurorae to 2 degrees, instead of 6 degrees if the ocean were not present.

Scientists estimate the ocean is 60 miles (100 kilometers) thick -- 10 times deeper than Earth's oceans -- and is buried under a 95-mile (150-kilometer) crust of mostly ice.

Scientists first suspected an ocean in Ganymede in the 1970s, based on models of the large moon. NASA's Galileo mission measured Ganymede's magnetic field in 2002, providing the first evidence supporting those suspicions. The Galileo spacecraft took brief "snapshot" measurements of the magnetic field in 20-minute intervals, but its observations were too brief to distinctly catch the cyclical rocking of the ocean's secondary magnetic field.

The new observations were done in ultraviolet light and could only be accomplished with a space telescope high above Earth's atmosphere, which blocks most ultraviolet light.

The team's results will be published online in the Journal of Geophysical Research: Space Physics on March 12.

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Diabetes, depression predict dementia risk in people with slowing minds

People with mild cognitive impairment are at higher risk of developing dementia if they have diabetes or psychiatric symptoms such as depression, finds a new review led by UCL researchers.

Mild cognitive impairment (MCI) is a state between normal ageing and dementia, where someone's mind is functioning less well than would be expected for their age. It affects 19% of people aged 65 and over, and around 46% of people with MCI develop dementia within 3 years compared with 3% of the general population.

The latest review paper, published in the American Journal of Psychiatry, analysed data from 62 separate studies, following a total of 15,950 people diagnosed with MCI. The study found that among people with MCI, those with diabetes were 65% more likely to progress to dementia and those with psychiatric symptoms were more than twice as likely to develop the condition.

"There are strong links between mental and physical health, so keeping your body healthy can also help to keep your brain working properly," explains lead author Dr Claudia Cooper (UCL Psychiatry). "Lifestyle changes to improve diet and mood might help people with MCI to avoid dementia, and bring many other health benefits. This doesn't necessarily mean that addressing diabetes, psychiatric symptoms and diet will reduce an individual's risk, but our review provides the best evidence to date about what might help."

The Alzheimer's Society charity recommends that people stay socially and physically active to help prevent dementia. Their guidelines also suggest eating a diet high in fruit and vegetables and low in meat and saturated fats, such as the Mediterranean diet.

"Some damage is already done in those with MCI but these results give a good idea about what it makes sense to target to reduce the chance of dementia," says senior author Professor Gill Livingston (UCL Psychiatry). "Randomised controlled trials are now needed."

Professor Alan Thompson, Dean of the UCL Faculty of Brain Sciences, says: "This impressive Systematic Review and meta-analysis from The Faculty of Brain Science's Division of Psychiatry underlines two important messages. Firstly, the impact of medical and psychiatric co-morbidities in individuals with mild cognitive impairment and secondly, the importance and therapeutic potential of early intervention in the prevention of dementia. Confirming these findings and incorporating appropriate preventative strategies could play an important part in lessening the ever-increasing societal burden of dementia in our ageing population."

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Ancient and modern cities aren't so different

Despite notable differences in appearance and governance, ancient human settlements function in much the same way as modern cities, according to new findings by researchers at the Santa Fe Institute and the University of Colorado Boulder.

Previous research has shown that as modern cities grow in population, so do their efficiencies and productivity. A city’s population outpaces its development of urban infrastructure, for example, and its production of goods and services outpaces its population. What's more, these patterns exhibit a surprising degree of mathematical regularity and predictability, a phenomenon called "urban scaling."

But has this always been the case?

SFI Professor Luis Bettencourt researches urban dynamics as a lead investigator of SFI's Cities, Scaling, and Sustainability research program. When he gave a talk in 2013 on urban scaling theory, Scott Ortman, now an assistant professor in the Department of Anthropology at CU Boulder and a former Institute Omidyar Fellow, noted that the trends Bettencourt described were not particular to modern times. Their discussion prompted a research project on the effects of city size through history.

To test their ideas, the team examined archaeological data from the Basin of Mexico (what is now Mexico City and nearby regions). In the 1960s — before Mexico City’s population exploded — surveyors examined all its ancient settlements, spanning 2000 years and four cultural eras in pre-contact Mesoamerica.

Using this data, the research team analyzed the dimensions of hundreds of ancient temples and thousands of ancient houses to estimate populations and densities, size and construction rates of monuments and buildings, and intensity of site use.

Their results indicate that the bigger the ancient settlement, the more productive it was.

“It was shocking and unbelievable,” says Ortman. “We were raised on a steady diet telling us that, thanks to capitalism, industrialization, and democracy, the modern world is radically different from worlds of the past. What we found here is that the fundamental drivers of robust socioeconomic patterns in modern cities precede all that.”

Bettencourt adds: “Our results suggest that the general ingredients of productivity and population density in human societies run much deeper and have everything to do with the challenges and opportunities of organizing human social networks.”

Though excited by the results, the researchers see the discovery as just one step in a long process. The team plans to examine settlement patterns from ancient sites in Peru, China, and Europe and study the factors that lead urban systems to emerge, grow, or collapse.

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Greenland is melting: The past might tell what the future holds

A team of scientists lead by Danish geologist Nicolaj Krog Larsen have managed to quantify how the Greenland Ice Sheet reacted to a warm period 8,000-5,000 years ago. Back then temperatures were 2-4 degrees C warmer than they are in the present. Their results have just been published in the scientific journal Geology, and are important as we are rapidly closing in on similar temperatures.

While the world is preparing for a rising global sea-level, a group of scientists led by Dr. Nicolaj Krog Larsen, Aarhus University in Denmark and Professor Kurt Kjær, Natural History Museum of Denmark ventured off to Greenland to investigate how fast the Greenland Ice Sheet reacted to past warming.

With hard work and high spirits the scientists spent six summers coring lakes in the ice free land surrounding the ice sheet. The lakes act as a valuable archive as they store glacial meltwater sediments in periods where the ice is advanced. That way is possible to study and precisely date periods in time when the ice was smaller than present.

"It has been hard work getting all these lake cores home, but is has definitely been worth the effort. Finally we are able to describe the ice sheet's response to earlier warm periods," says Dr. Nicolaj Krog Larsen of Aarhus University, Denmark.

Evidence has disappeared

The size of the Greenland Ice Sheet has varied since the Ice Age ended 11,500 years ago, and scientists have long sought to investigate the response to the warmest period 8,000-5,000 years ago where the temperatures were 2-4 °C warmer than they are in the present.

"The glaciers always leave evidence about their presence in the landscape. So far the problem has just been that the evidence is removed by new glacial advances. That is why it is unique that we are now able to quantify the mass loss during past warming by combining the lake sediment records with state-of-the-art modelling," says Professor Kurt Kjær, Natural History Museum of Denmark.

16 cm of global sea-level rise from Greenland

Their results show that the ice had its smallest extent exactly during the warming 8,000-5,000 years ago -- with that knowledge in hand they were able to review all available ice sheet models and choose the ones that best reproduced the reality of the past warming.

The best models show that during this period the ice sheet was losing mass at a rate of 100 Gigaton pr. year for several thousand years, and delivered the equivalent of 16 cm of global sea-level rise when temperatures were 2-4 °C warmer. For comparison, the mass loss in the last 25 years has varied between 0-400 Gigaton pr. year, and it is expected that the Arctic will warm 2-7 °C by the year 2100.

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Key indicator for successful treatment of infertile couples

Couples have choices in infertility treatments. A recent finding by Marlene Goldman, MS, ScD of the Geisel School of Medicine at Dartmouth and colleagues, published in Fertility and Sterility, gives doctors and couples a new tool to determine which technique may be more effective for their situation.

"As a woman approaches menopause, her level of follicle stimulating hormone (FSH) rises," explained Goldman. "A higher FSH level is a key indicator that the woman may not be as fertile as necessary to conceive using certain common methods of infertility treatment."

The study determined if FSH and estrogen at the upper limits of normal, as measured on day three of the menstrual cycle, could predict treatment success as measured in live birth rates. The essential question was: should women with higher levels of FSH and estrogen be "fast-tracked" to in vitro fertilization (IVF), bypassing the conventional treatment trajectory?

Goldman and collaborators recorded no live births in the group with FSH and estrogen at the upper limits of normal, yet when the couples later pursued IVF, 33% were able to have babies.

"Some women express a preference to begin treatment for infertility with controlled ovarian hyper-stimulation (COH), whether by pill or injection, along with intrauterine insemination (IUI)," said Goldman. "When counseling women with day-three testing for FSH or estrogen at the upper limits of normal, it may be helpful for them to know that COH-IUI has not been successful in others with similar levels. Fortunately, IVF is a successful treatment for many women and if we can 'fast-track' them to IVF, bypassing COH-IUI, treatments will be quicker and may be less expensive."

Insurance companies may use FSH levels to determine if they will continue payments for future treatment cycles in women with high levels.

The next steps for Goldman include probing what makes IVF so successful and how to keep the success rate while reducing costs.

Marlene Goldman, MS, ScD, is Professor of Obstetrics & Gynecology, and of Community & Family Medicine at Dartmouth's Geisel School of Medicine. Her work in cancer is facilitated by Dartmouth's Norris Cotton Cancer Center in Lebanon, NH. She is the Vice-chair for Research in the Department of Obstetrics & Gynecology at Dartmouth-Hitchcock Medical Center. This work was funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development and National Institutes of Health grants RO1 HD38561 and RO1 HD44547. Her collaborators included Richard Reindollar, MD PI; Daniel J. Kaser, MD, first author; June L. Fung, PhD, all from Dartmouth; and Michael M. Alper, MD from Boston IVF.

About Norris Cotton Cancer Center at Dartmouth-Hitchcock Norris Cotton Cancer Center combines advanced cancer research at Dartmouth and the Geisel School of Medicine with patient-centered cancer care provided at Dartmouth-Hitchcock Medical Center in Lebanon, NH, at Dartmouth-Hitchcock regional locations in Manchester, Nashua, and Keene, NH, and St. Johnsbury, VT, and at 12 partner hospitals throughout New Hampshire and Vermont. It is one of 41 centers nationwide to earn the National Cancer Institute's "Comprehensive Cancer Center" designation. Learn more about Norris Cotton Cancer Center research, programs, and clinical trials online at cancer.dartmouth.edu.

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Mars exploration: NASA's MAVEN spacecraft completes first deep dip campaign

This image shows an artist concept of NASA's Mars Atmosphere and Volatile Evolution (MAVEN) mission.

NASA's Mars Atmosphere and Volatile Evolution has completed the first of five deep-dip maneuvers designed to gather measurements closer to the lower end of the Martian upper atmosphere.

"During normal science mapping, we make measurements between an altitude of about 150 km and 6,200 km (93 miles and 3,853 miles) above the surface," said Bruce Jakosky, MAVEN principal investigator at the University of Colorado's Laboratory for Atmospheric and Space Physics in Boulder. "During the deep-dip campaigns, we lower the lowest altitude in the orbit, known as periapsis, to about 125 km (78 miles) which allows us to take measurements throughout the entire upper atmosphere."

The 25 km (16 miles) altitude difference may not seem like much, but it allows scientists to make measurements down to the top of the lower atmosphere. At these lower altitudes, the atmospheric densities are more than ten times what they are at 150 km (93 miles).

"We are interested in the connections that run from the lower atmosphere to the upper atmosphere and then to escape to space," said Jakosky. "We are measuring all of the relevant regions and the connections between them."

The first deep dip campaign ran from Feb. 10 to 18. The first three days of this campaign were used to lower the periapsis. Each of the five campaigns lasts for five days allowing the spacecraft to observe for roughly 20 orbits. Since the planet rotates under the spacecraft, the 20 orbits allow sampling of different longitudes spaced around the planet, providing close to global coverage.

This month's deep dip maneuvers began when team engineers fired the rocket motors in three separate burns to lower the periapsis. The engineers did not want to do one big burn, to ensure that they didn't end up too deep in the atmosphere. So, they "walked" the spacecraft down gently in several smaller steps.

"Although we changed the altitude of the spacecraft, we actually aimed at a certain atmospheric density," said Jakosky. "We wanted to go as deep as we can without putting the spacecraft or instruments at risk."

Even though the atmosphere at these altitudes is very tenuous, it is thick enough to cause a noticeable drag on the spacecraft. Going to too high an atmospheric density could cause too much drag and heating due to friction that could damage spacecraft and instruments.

At the end of the campaign, two maneuvers were conducted to return MAVEN to normal science operation altitudes. Science data returned from the deep dip will be analyzed over the coming weeks. The science team will combine the results with what the spacecraft has seen during its regular mapping to get a better picture of the entire atmosphere and of the processes affecting it.

One of the major goals of the MAVEN mission is to understand how gas from the atmosphere escapes to space, and how this has affected the planet's climate history through time. In being lost to space, gas is removed from the top of the upper atmosphere. But it is the thicker lower atmosphere that controls the climate. MAVEN is studying the entire region from the top of the upper atmosphere all the way down to the lower atmosphere so that the connections between these regions can be understood.

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Brain's iconic seat of speech goes silent when we actually talk

New findings will better help map out the brain's speech regions.

For 150 years, the iconic Broca's area of the brain has been recognized as the command center for human speech, including vocalization. Now, scientists at UC Berkeley and Johns Hopkins University in Maryland are challenging this long-held assumption with new evidence that Broca's area actually switches off when we talk out loud.

The findings, reported in the Proceedings of the National Academy of Sciences journal, provide a more complex picture than previously thought of the frontal brain regions involved in speech production. The discovery has major implications for the diagnoses and treatments of stroke, epilepsy and brain injuries that result in language impairments.

"Every year millions of people suffer from stroke, some of which can lead to severe impairments in perceiving and producing language when critical brain areas are damaged," said study lead author Adeen Flinker, a postdoctoral researcher at New York University who conducted the study as a UC Berkeley Ph.D. student. "Our results could help us advance language mapping during neurosurgery as well as the assessment of language impairments."

Flinker said that neuroscientists traditionally organized the brain's language center into two main regions: one for perceiving speech and one for producing speech.

"That belief drives how we map out language during neurosurgery and classify language impairments," he said. "This new finding helps us move towards a less dichotomous view where Broca's area is not a center for speech production, but rather a critical area for integrating and coordinating information across other brain regions."

In the 1860s, French physician Pierre Paul Broca pinpointed this prefrontal brain region as the seat of speech. Broca's area has since ranked among the brain's most closely examined language regions in cognitive psychology. People with Broca's aphasia are characterized as having suffered damage to the brain's frontal lobe and tend to speak in short, stilted phrases that often omit short connecting words such as "the" and "and."

Specifically, Flinker and fellow researchers have found that Broca's area -- which is located in the frontal cortex above and behind the left eye -- engages with the brain's temporal cortex, which organizes sensory input, and later the motor cortex, as we process language and plan which sounds and movements of the mouth to use, and in what order. However, the study found, it disengages when we actually start to utter word sequences.

"Broca's area shuts down during the actual delivery of speech, but it may remain active during conversation as part of planning future words and full sentences," Flinker said.

The study tracked electrical signals emitted from the brains of seven hospitalized epilepsy patients as they repeated spoken and written words aloud. Researchers followed that brain activity -- using event-related causality technology -- from the auditory cortex, where the patients processed the words they heard, to Broca's area, where they prepared to articulate the words to repeat, to the motor cortex, where they finally spoke the words out loud.

In addition to Flinker, other co-authors and researchers on the study are Robert Knight and Avgusta Shestyuk at the Helen Wills Neuroscience Institute at UC Berkeley, Nina Dronkers at the Center for Aphasia and Related Disorders at the Veterans Affairs Northern California Health Care System, and Anna Korzeniewska, Piotr Franaszczuk and Nathan Crone at Johns Hopkins School of Medicine.

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