Zeptonewtons: Tiny Units of Measure of FORCE

     A single atom can gauge tiny electromagnetic forces.
The unit of measure of force, a zeptonewton, is equal to one billionth of a trillionth of a newton.    

      Scientists detected a tiny force using a charged atom (illustrated as a red sphere above), which moved (orange) when pelted with laser light (purple). A lens focused light emitted from the atom into a moving image (black arrow).

     Scientists used an atom of the element ytterbium (above) to sense an electromagnetic force smaller than 100 zeptonewtons, researchers report March 23, 2018,  in Science Advances. That’s less than 0.0000000000000000001 newtons (with 18 zeroes after the decimal.) At about the same strength as the gravitational pull between a person in Dallas and another in Washington, D.C., that’s downright feeble.

     After removing one of the atom’s electrons, researchers trapped the atom using electric fields and cooled it to less than a thousandth of a degree above absolute zero (–273.15° Celsius) by hitting it with laser light. 

      That light, counterintuitively, can cause an atom to chill out. The laser also makes the atom glow, and scientists focused that light into an image with a miniature Fresnel lens (as pictured above), a segmented lens like those used to focus lighthouse beams.

     Monitoring the motion of the atom’s image allowed the researchers to study how the atom responded to electric fields, and to measure the minuscule force caused by particles of light scattering off the atom, a mere 95 zeptonewtons.

I'm a little early for May, but, May the Fo(u)rth be with you,
Steph
    

Ice-VII: Deep Ice, Tectonic Slabs, and Diamond Inclusions

      Ice is found deep within the hot interior of the earth. Let that statement sink in. In research published today, a form of super-compact ice, found embedded in diamonds, offers the first direct clue that there is abundant water more than 610 kilometers deep in the mantle.

      This ice, identified by its crystal structure and called ice-VII, doesn’t exist at Earth’s surface. It forms only at pressures greater than about 24 gigapascals — corresponding to depths between 610 and 800 kilometers, researchers report today in Science. The structure of ice-VII comprises a hydrogen bond framework in the form of two interpenetrating (but non-bonded) sublattices. Hydrogen bonds pass through the center of the water hexamers (as shown above, and, to some degree below) and thus do not connect the two lattices. 

  

      Ice-VII's presence in diamonds suggests that there is water-rich fluid in the transition zone between the upper and lower mantle, and even into the top of the lower mantle.

     “This is really the first time that we see water at such depths,” says Dr. Oded Navon, a mantle petrologist at the Hebrew University of Jerusalem.

      When slabs of earth’s crust sink into the mantle layer below, they drag ocean water with them. How deep the slabs sink has been a long-standing question. Researchers have suspected that abundant aqueous fluid exists in the deep mantle, carried there by slabs bearing water-rich minerals that shed their water when they reach the transition zone. But scientists have not previously found direct evidence of that water.

     That is where diamonds come in. Diamonds form at high temperatures and pressures, crystallizing in pockets rich in the mineral carbonate before being carried to the surface with erupting magma. As the diamond crystals form, they can enclose tiny amounts of fluid or rock from their surroundings. These impurities represent tiny capsules of mantle. Diamond inclusions are the only direct window scientists have into the fabric of earth more than a kilometer beneath the surface.

     Dr. Oliver Tschauner, a mineralogist at the University of Nevada, Las Vegas, and his colleagues set out to study diamond inclusions, but they weren’t looking for ice. They were hunting for signs of a molecular form of carbon dioxide that might help reveal clues to the cycling of carbon from slabs into the mantle. The researchers used a variety of techniques, including X-ray diffraction, infrared spectroscopy and X-ray fluorescence, to try to identify the composition of the inclusions within three diamonds, one from China and two from southern Africa.

      Instead of carbon dioxide, the team saw a telltale pattern in how some of the X-rays scattered as they passed through the diamond. That pattern pointed to ice-VII. The presence of that extremely high-pressure form of ice was a powerful clue to the depth at which the diamond must have formed. The diamonds also contained separate inclusions of fluids rich in certain salts, such as magnesium calcite and halite, and of carbon-rich fluids. 

     Water-rich fluids deep in the mantle could be important for driving the circulation that fuels the movements of tectonic plates and the eruptions of volcanoes. The presence of water can make it easier for rocks to melt, Dr.  Navon says, by lowering the melting point of hot rock under pressure. Additionally, fluids can help redistribute heat within the mantle.

     In addition, some large, heat-producing radioactive elements such as potassium, thorium and uranium don’t fit easily into the rigid crystalline structures of minerals, so scientists prefer melted rock when it’s available. “You just need a little bit of fluid, and they are moving into the melt,” Dr. Navon adds.

     The study also raised another mystery. Fluid inclusions within diamonds originating at shallower depths, perhaps 150 to 200 kilometers below the surface, contain a mélange of water, salt, and carbonates. But Dr. Tschauner and his colleagues found that in their deep diamonds, the inclusions are sequestered individually: ice in one inclusion, carbonates in another, salts in yet a third. “We were surprised that they were all separate rather than occurring together,” Dr. Tschauner said.  

Any ideas about this mysterious separation in the materials in inclusions? 

And, how cool to have remnants of tectonic slabs as inclusions in your jewelry!
Steph

Extensive Mid-Oceanic Magma Eruption at the Cretaceous-Paleogene Time Boundary

     The asteroid that hit earth 66 million years ago appears to have caused large amounts of magma to spew out of the bottom of the ocean, a new study of seafloor data finds.

      The discovery, described today in the journal Science Advances, adds to the picture of an extinction event that was as complex as it was deadly.

      For decades, researchers have pointed to a cataclysmic asteroid crashing into the planet as the reason the dinosaurs, and many other species of life on Earth, were wiped out during the Cretaceous-Paleogene (K-Pg) extinction event. That impact, which scientists think left the roughly 110-mile-wide Chicxulub crater in the Gulf of Mexico, would have vaporized living things nearby and sent choking clouds of debris into the air, obscuring the sun.

      But scientists have also pointed to another culprit: the Deccan Traps in present-day India, one of the largest volcanic provinces in the world, which just happened to be very active at the time of the extinction event. The ash and noxious gases from the Deccan Traps are really what killed the dinosaurs, some scientists say, downplaying the asteroid's role.

     "People still argue about which one was actually the primary driver of environmental changes that resulted in the death of dinosaurs," said senior author Dr. Leif Karlstrom, an earth scientist at the U. of Oregon.

     Researchers have also suggested that perhaps the two were connected — perhaps the asteroid triggered Deccan Trap volcanism, producing a brutal one-two punch that ultimately knocked out roughly three-quarters of the earth's plant and animal species. But recent work has shown that the traps started spewing roughly a quarter-million years before the asteroid hit, Dr. Karlstrom said.

     Yet, scientists have wondered if there might indeed be some kind of connection between the two. And lead author Dr. Joseph Byrnes, a geophysicist at the U. of Minnesota, realized something: If the asteroid impact had had a major impact on volcanism at the time, that effect should have shown up in the activity along the Earth's mid-ocean ridges. So he and Dr. Karlstrom went looking for it.

     As we've discussed here at Partial Ellipsis of the Sun before, the mid-ocean ridges are long cracks in the Earth's crust at the bottom of the ocean floor where tectonic plates meet. As the plates pull apart, hot magma rises up between them, flowing out on either side of the crack before cooling, creating new seafloor in the process. With more than 40,000 miles of ridges, this network of cracks forms the longest mountain chain on earth.

   
     Scientists used magnetic data compiled by other researchers and combined it with another data set showing the gravitational field of the surface beneath the ocean. The stronger the gravitational field in a given spot, the more mass there is. 

    "We have a topographic map of the Earth's surface and we have topographic maps of Mars and Venus, but we don't have that for the ocean floor," Dr. Byrnes said. "We have it for places where people have taken ships, but it would take something like 900 years to survey the whole ocean floor. It's just too resource-intensive — so we have to use the gravitational anomalies as a proxy."

     The graph below shows a spike in the creation of new seafloor about 66 million years ago. That's when the Chicxulub asteroid struck the Earth, wiping out the dinosaurs. The impact also instigated the release of massive amounts of magma.

     Sure enough, the scientists found that at the time the asteroid hit the Earth, there was a sudden surge in the magma pouring out of these mid-ocean ridges, which put out on the order of a hundred thousand to a million cubic kilometers of volcanic material. That's not too far behind the estimated several million cubic kilometers or so of magma produced by the Deccan Traps.

     It's possible that the powerful seismic waves produced by the impact triggered the release of reservoirs of magma beneath the surface, Dr. Karlstrom said. And if it affected the mid-ocean ridges this way, it could have played a similar role in the Deccan Traps, triggering even more volcanism than before.

     The mid-ocean ridges, then, could be a bellwether for a similar phenomenon occurring in the already-active Deccan Traps.

       But did that marine magma release do any damage of its own? While it's unclear whether this extra load of ocean floor magma worsened the extinction event, it could potentially have played a role by further acidifying the oceans. Previous work indicates that marine species that were more sensitive to ocean acidification were worse hit by the extinction event. But probing that possibility will take more research, the scientists added.

      "That's what we need to work on next, I would say: trying to tease out what the effects on the environment were of the volcanic activity," Dr. Byrnes said.

Thoughts on this new data? Have you been to the Deccan Traps?
Steph

Speaking of stitches, here's the full quilt my friend made:

     

Bee Bedevilments: Colony Collapse Disorder and More

      Colony Collapse Disorder (CCD) was one of the most striking mysteries in the news 11-12 years ago; honeybee workers were vanishing fast for no clear reason. To this day, that puzzle has never been entirely solved, researchers say.

     And perhaps it never will be. Colony collapse disorder has faded in recent years as mysteriously as it began. It’s possible the disappearances could start up again, but meanwhile bees are facing other problems.

     CCD probably peaked around 2007 and has faded since, says Dr. Jeff Pettis, who during the height of national curiosity was running the Beltsville, MD, honeybee lab for the U.S. Department of Agriculture. Five years have passed since Dennis vanEngelsdorp, who studies bee health at the University of Maryland  has seen a “credible case” of colony collapse (see below in the lower part of the image.)

     Beekeepers still report some cases, but Dr. Pettis and Dr. vanEngelsdorp aren’t convinced such cases really are colony collapse disorder, a term that now gets used for a myriad of things that are bad for bees. To specialists, colony collapse is a specific phenomenon. An apparently healthy colony over the course of days or a few weeks loses much of its workforce, while eggs and larvae, and often the queen herself, remain alive. Also food stores in collapsing colonies don’t get raided by other bees as a failing colony’s treasures usually do.

      “I think I know what happened,” says Dr. Pettis, now in Salisbury, MD, consulting on pollinator health. His proposed scenario for CCD, like those of some other veterans of the furor, is complex and doesn’t rest on a single exotic killer. But so far, no experiment has nailed a proof.

     Looking back, Pettis realizes he had heard about what might have been early cases of CCD, described as colonies “just falling apart,” for several years before the phenomenon made headlines. Then in November 2006, Pennsylvania beekeeper David Hackenberg, as usual, sent his colonies to Florida for the winter. They arrived in fine shape. Soon after, however, many buzzing colonies had shrunk to stragglers. Yet there were no dire parasite infestations and no dead bee bodies in sight.

      “It was, ‘OK, something weird just happened,’ ” remembers Dr. Jay Evans of the USDA’s honeybee lab in Beltsville. “It looked like a ‘flu,’ something that kind of swept through miraculously fast.”

      No single menace, however, could be tightly linked to every sick colony, or only to sick colonies. Varroa mites, small hive beetles, Nosema fungi, deformed wing virus, unusual signs of pesticide exposure, for instance —screening techniques at the time just weren’t picking up a clear pattern in any of these bee bedevilments.

     Entomologists were hounded by the press, not to mention leaned on by politicians and pursued by would-be entrepreneurs. “For me, what made it rewarding,” Dr. Pettis says, “was that people were learning about the value of pollination.”

      A Columbia University researcher who had identified pathogens in mysterious human disease outbreaks looked at the problem. Dr. Ian Lipkin had never worked with bees, but he and his lab collaborated with entomologists and other bee specialists to search for any genetic signature of a pathogen appearing only in collapsing colonies. The approach of searching through mass samples, with their messy traces of gut microbes and random parasites, is now familiar as metagenomics. At the time, this way of searching for pathogens was groundbreaking, says collaborator Diana Cox-Foster, then at Penn State U. The resulting paper, in Science, pointed to several viruses, especially the previously obscure Israeli Acute Paralysis Virus, or IAPV. That emphasis on IAPV, which got a lot of attention at the time, hasn’t held up well. “It’s not 100 percent ruled out,” Evans says. But the explanation’s main problem is shared by other threats proposed as a single cause of CCD. After finding IAPV or another presumed single menace in sick bees in one place, he says, “you could go to other apiaries that were collapsing and not find it, or you could find it in healthier colonies.”

      As an apiary inspector for Pennsylvania at the time, vanEngelsdorp monitored for signs of collapse in over 200 hives. “We tried to watch it happen but we couldn’t,” he says. None collapsed. Even finding the sickest bees in collapsing colonies was a challenge. Doomed bees presumably flew off in multiple directions, and birds or other scavengers usually found the bees before scientists could.

     Dr. Pettis now sees the disaster as a two-step process. Various stressors such as poor nutrition and pesticide exposure weakened bees so much that a virus, maybe IAPV, could quickly kill them in droves. Evans, too, sees various stressors mixing and matching. When pressed for his best guess, he says “all of the above.”

       Dr. Cox-Foster has managed to re-create part of the process, the vanishing effect that marked the end for stressed bees. When she infected honeybee colonies in a greenhouse with a virus, the sick bees left the hive but were trapped by the greenhouse walls before dispersing too far to be found. (Of course, this experiment doesn’t demonstrate how colonies with no sign of a virus died.

     That tendency for sick bees to leave hives, Dr. vanEngelsdorp proposes, could have developed as a hygiene benefit. “Altruistic suicide,” as social-insect biologists call it. Flying away from the colony could minimize a sick bee’s tendency to pass disease to the rest of the hive.

     Colony losses each year are still running higher than beekeepers say would be acceptable (gray bar in the image below). Even though hives can be split so numbers eventually build up again, the slowdown and expense raise the costs of pollination.

      Today, hive losses remain high even with CCD waning or gone, according to national surveys by the Bee Informed Partnership, a nonprofit bee health collaboration. Beekeepers typically note that they either expect or can tolerate annual losses between 15 and 20 percent of their total number of colonies. Yet from April 2016 until March 2017, losses across the United States ran at about a third of hives. And that was a so-called good year, the second-lowest loss in the seven years with data on annual losses.

      Classic CCD may not be as much of a threat these days, but the “four p’s” — poor nutrition, pesticides, pathogens and parasites — are, says Dr. Cox-Foster, now at a USDA lab for pollinating insects in Logan, Utah. Coping with the four p’s may not fire the imaginations of armchair entomologists. But it’s more than enough of a challenge for the bees.

       Answer? Choose B (but it's still a confounding mystery.)

Bee well,
Steph

2017: 74 Interesting Science, Technology, and Health Links

     Here are 74 interesting science, technology, and health stories in this 2017 year-end article from The Atlantic. Enjoy all the links from how flamingos easily stand on one leg (#2). . .

in formation. . .

to a large waterfall in Antarctica where the Nansen Ice Shelf meets the sea (#19). . .

to the way hummingbirds drink nectar using tongues that are so long that, when retracted, they coil up inside the birds’ heads, around their skulls and eyes (#59). . .

to genetically distinct uptown versus downtown rats in New York City (#60). . .

to the oldest rocks on earth (4 billion years old having fossil traces in them in the Torngat Mountains in Canada (#67) to. . . wherever the links take you.

      Which links were most intriguing for you? Which did you skip past quickly (#13 for me)?

      I'll leave the mole rats and their oxygen needs for you to discover (#74).

All the best for a healthy, happy, and scientifically stimulating 2018!

Steph

Something to Crow About: Happy Hooking, a Relatively New Tool Skill

      New Caledonian crows are the only species besides humans known to manufacture hooked tools in the wild. These birds produce these remarkable tools from the side branches of certain plants, carefully 'crafting' a crochet-like hook that can be used for snagging insect prey.

      The study, published in Current Biology on December 7, 2017, reveals how crows manage to fashion particularly efficient tools, with well-defined 'deep' hooks.

      The hook is widely regarded as one of humankind's most important innovations, with skillful reshaping, a useless piece of raw material is transformed into a powerful tool. While our ancestors started making stone tools over 3 million years ago, hooks are a surprisingly recent advance; the oldest known fish hooks are just 23,000 years old.

         Project leader Dr. Christian Rutz has conducted field research on New Caledonian crows for over a decade. His team recently noticed that crows' hooked tools vary considerably in size and shape. While some tools only exhibit a small extension at the tip, others have deeper hooks.

     Dr. Rutz explains: "We suspected that tools with pronounced hooks are more efficient, and were able to confirm this in controlled experiments with wild-caught crows. The deeper the hook, the faster birds winkled (to extract with difficulty) bait from holes in wooden logs."

     This finding raised the intriguing question of what it takes to make such well-formed hooks. The researchers started planning their study by imagining how humans would approach a comparable task. "When a craftsperson carves a tool from a piece of wood, two things ensure a quality product: good raw materials and skill," Dr. Rutz said.

      Researchers found that the same, apparently, applies to New Caledonian crows. The researchers discovered that the depth of the hook was influenced by both the properties of the plant material, and the technique crows used for detaching branches. When birds made controlled cuts with their sharp bills, the resulting hooks were significantly deeper than when they used a 'sloppier' alternative method of simply pulling off branches. Careful cutting may leave more wooden material at the tip of the stick from which the hook can subsequently be 'sculpted'.

     Surprisingly, adult crows, which are expected to have considerable tool-making experience, did not produce the deepest hooks and regularly employed the 'quick-and-dirty' manufacture technique. Dr. Rutz notes that making very deep hooks may not be the best strategy in the wild: "It probably takes more time and effort to make such tools, and experienced birds may try to avoid these costs. It is also possible that deep hooks break more easily when inserted into narrow holes and crevices."

      Dr. Christophe Boesch, a world-leading chimpanzee expert and Director of the Max Planck Institute of Evolutionary Anthropology in Leipzig, Germany, comments: "We have recently discovered that chimpanzees routinely use naturally-hooked stems to fish for algae, but they don't actively craft these hooks. The crows can reshape plant material with their pointed bills, which act like 'precision pliers', but this would be very difficult for chimpanzees with their large fingers."

     The present study is the first to examine in a non-human animal what factors determine the morphology of crafted tools, and as a consequence, their foraging efficiency. Paleo-anthropologists try to understand how our ancestors produced relatively complex tool shapes from basic raw materials, such as wood, bone or seashell, but they face the challenge that the manufacture process cannot be directly observed.

      The New Caledonian crow, with its remarkable ability to fashion hooked tools from plant stems, provides a fascinating window into humans' evolutionary past.

Hooked on Crows,
Steph