Thursday, November 30, 2017

When the 'Mind's Eye" Blinks, It Proves 'Paying Attention' Is Not Just a Figure of Speech



When your attention shifts from one place to another, your brain blinks. The blinks are momentary unconscious gaps in visual perception and came as a surprise to the team of Vanderbilt psychologists who discovered the phenomenon while studying the benefits of attention.

"Attention is beneficial because it increases our ability to detect visual signals even when we are looking in a different direction," said Assistant Professor of Psychology Alex Maier, who directed the study. "The 'mind's eye blinks' that occur every time your attention shifts are the sensory processing costs that we pay for this capability."

Details of their study are described in a paper titled "Spiking suppression precedes cued attentional enhancement of neural responses in primary visual cortex" published online Nov. 23 by the journal Cerebral Cortex.

When your attention shifts, your brain 'blinks.'

Credit: Keith Wood, Vanderbilt University


"There have been several behavior studies in the past that have suggested there is a cost to paying attention. But our study is the first to demonstrate a sensory brain mechanism underlying this phenomenon," said first author Michele Cox, who is a psychology doctoral student at Vanderbilt.

The research was conducted with macaque monkeys that were trained to shift their attention among different objects on a display screen while the researchers monitored the pattern of neuron activity taking place in their brains. Primates are particularly suited for the study because they can shift their attention without moving their eyes. Most animals do not have this ability.

"We trained macaques to play a video game that rewarded them with apple juice when they paid attention to certain visual objects. Once they became expert at the game, we measured the activity in their visual cortex when they played," said Maier.

By combining advanced recording techniques that simultaneously track large numbers of neurons with sophisticated computational analyses, the researchers discovered that the activity of the neurons in the visual cortex were momentarily disrupted when the game required the animals to shift their attention. They also traced the source of the disruptions to parts of the brain involved in guiding attention, not back to the eyes.

Mind's eye blink is closely related to "attentional blink" that has been studied by Cornelius Vanderbilt Professor of Psychology David Zald and Professor of Psychology René Marois. Attentional blink is a phenomenon that occurs when a person is presented with a rapid series of images. If the spacing between two images is too short, the observer doesn't detect the second image. In 2005, Zald determined that the time of temporary blindness following violent or erotic images was significantly longer than it is for emotionally neutral images.




Contacts and sources:
David F Salisbury
Vanderbilt University

Diet Success May Depend on Your DNA



We can add one more thing to the list of traits affected by genetics: how our bodies respond to a particular diet. Who we are may be as important as what we eat when it comes to weight and health, research says

Research in animal models with different genetics shows that one diet really doesn't fit all, and what works for some may not be best for others, according to a Texas A&M study published in the journal Genetics.

"Dietary advice, whether it comes from the United States government or some other organization, tends to be based on the theory that there is going to be one diet that will help everyone," said David Threadgill, PhD, with the Texas A&M College of Medicine and College of Veterinary Medicine & Biomedical Sciences, senior author of the study. "In the face of the obesity epidemic, it seems like guidelines haven't been effective."

Credit: Texas A&M University Health Science Center

Threadgill thinks he knows why. The researchers used four different groups of animal models to look at how five diets affect health over a six-month period. The genetic differences within each group were almost non-existent, while the genetics between any two of the groups would translate to roughly the same as those of two unrelated people. The researchers chose the test diets to mirror those eaten by humans--an American-style diet (higher in fat and refined carbs, especially corn) and three that have gotten publicity as being 'healthier': Mediterranean (with wheat and red wine extract), Japanese (with rice and green tea extract) and ketogenic, or Atkins-like (high in fat and protein with very few carbs). The fifth diet was the control group who ate standard commercial chow.

Although some so-called healthy diets did work well for most individuals, one of the four genetic types did very poorly when eating the Japanese-like diet, for example. "The fourth strain, which performed just fine on all of the other diets, did terrible on this diet, with increased fat in the liver and markings of liver damage," said William Barrington, lead author on the study and a recently graduated PhD student from the Threadgill lab.

A similar thing happened with the Atkins-like diet: two genetic types did well, and two did very badly. "One became very obese, with fatty livers and high cholesterol," Barrington said. The other had a reduction in activity level and more body fat, but still remained lean. "This equates to what we call 'skinny-fat' in humans, in which someone looks to be a healthy weight but actually has a high percentage of body fat."

"In humans, you see such a wide response to diets," Barrington said. "We wanted to find out, in a controlled way, what was the effect of the genetics." They measured physical signs, especially evidence of metabolic syndrome, which is a collection of signs of obesity-related problems, including high blood pressure and cholesterol, fatty liver and levels of blood sugar. They also studied any behavioral differences, from how much they moved around to how much they ate.

"I wanted to get the diets as close to popular human diets as possible," Barrington said. "We matched fiber content and matched bioactive compounds thought to be important in disease."

Perhaps as could be expected, both in earlier research and in anecdotal evidence in humans, the animal models tended not to do great on the American-style diet. A couple of the strains became very obese and had signs of metabolic syndrome. Other strains showed fewer negative effects, with one showing few changes except for having somewhat more fat in the liver. With the Mediterranean diet, there was a mix of effects. Some groups were healthy, while others experienced weight gain, although it was less severe than in the American diet. Interestingly, these effects held, even though the quantity of consumption was unlimited.

The results demonstrated that a diet that makes one individual lean and healthy might have the complete opposite effect on another. "My goal going into this study was to find the optimal diet," Barrington said. "But really what we're finding is that it depends very much on the genetics of the individual and there isn't one diet that is best for everyone."

The research team's future work will focus on determining which genes are involved in the response to the diets. "One day, we'd love to develop a genetic test that could tell each person the best diet for their own genetic makeup," Barrington said. "There might be a geographical difference based on what your ancestors ate, but we just don't know enough to say for sure yet."




Contacts and sources:
Christina B. Sumners
 Texas A&M  University

Gravitational Waves May Reveal Black Hole Origin Clues

The detection of gravitational waves has given astronomers a new way of looking at the universe, and a new study shows how these ripples in the fabric of spacetime might confirm or rule out the existence of a certain type of black hole.

 A new study published in Physical Review Letters outlines how scientists could use gravitational wave experiments to test the existence of primordial black holes, gravity wells formed just moments after the Big Bang that some scientists have posited could be an explanation for dark matter.

“We know very well that black holes can be formed by the collapse of large stars, or as we have seen recently, the merger of two neutron stars,” said Savvas Koushiappas, an associate professor of physics at Brown University and coauthor of the study with Avi Loeb from Harvard University. “But it’s been hypothesized that there could be black holes that formed in the very early universe before stars existed at all. That’s what we’re addressing with this work.”

The LIGO experiment has made several detections of colliding black holes. Future gravitational wave experiments might detect such events much further back in time, which could shed light on how black holes form.
Credit: The SXS (Simulating eXtreme Spacetimes) Project

The idea is that shortly after the Big Bang, quantum mechanical fluctuations led to the density distribution of matter that we observe today in the expanding universe. It’s been suggested that some of those density fluctuations might have been large enough to result in black holes peppered throughout the universe. These so-called primordial black holes were first proposed in the early 1970s by Stephen Hawking and collaborators but have never been detected — it’s still not clear if they exist at all.

The ability to detect gravitational waves, as demonstrated recently by the Laser Interferometer Gravitational-Wave Observatory (LIGO), has the potential to shed new light on the issue. Such experiments detect ripples in the fabric of spacetime associated with giant astronomical events like the collision of two black holes. LIGO has already detected several black hole mergers, and future experiments will be able to detect events that happened much further back in time.

“The idea is very simple,” Koushiappas said. “With future gravitational wave experiments, we’ll be able to look back to a time before the formation of the first stars. So if we see black hole merger events before stars existed, then we’ll know that those black holes are not of stellar origin.”

Cosmologists measure how far back in time an event occurred using redshift — the stretching of the wavelength of light associated with the expansion of the universe. Events further back in time are associated with larger redshifts. For this study, Koushiappas and Loeb calculated the redshift at which black hole mergers should no longer be detected assuming only stellar origin.

They show that at a redshift of 40, which equates to about 65 million years after the Big Bang, merger events should be detected at a rate of no more than one per year, assuming stellar origin. At redshifts greater than 40, events should disappear altogether.

“That’s really the drop-dead point,” Koushiappas said. “In reality, we expect merger events to stop well before that point, but a redshift of 40 or so is the absolute hardest bound or cutoff point.”

A redshift of 40 should be within reach of several proposed gravitational wave experiments. And if they detect merger events beyond that, it means one of two things, Koushiappas and Loeb say: Either primordial black holes exist, or the early universe evolved in a way that’s very different from the standard cosmological model. Either would be very important discoveries, the researchers say.

For example, primordial black holes fall into a category of entities known as MACHOs, or Massive Compact Halo Objects. Some scientists have proposed that dark matter — the unseen stuff that is thought to comprise most of the mass of the universe — may be made of MACHOs in the form of primordial black holes. A detection of primordial black holes would bolster that idea, while a non-detection would cast doubt upon it.

The only other possible explanation for black hole mergers at redshifts greater than 40 is that the universe is “non-Gaussian.” In the standard cosmological model, matter fluctuations in the early universe are described by a Gaussian probability distribution. A merger detection could mean matter fluctuations deviate from a Gaussian distribution.

“Evidence for non-Gaussianity would require new physics to explain the origin of these fluctuations, which would be a big deal,” Loeb said.

The rate at which detections are made past a redshift of 40 — if indeed such detections are made — should indicate whether they’re a sign of primordial black holes or evidence for non-Gaussianity. But a non-detection would present a strong challenge to those ideas.



Contacts and sources:
Kevin Stacey 
Brown University

The Origin of Rain and Smells

Everyday questions like what really causes clouds and rain, what gives sparkling wines their distinctive aroma and why do tires generate so much smoke when they burn have answers that are intimately connected.

The University of Seville teacher Alfonso Gañán has developed a particularly exact model to show the origin of all these phenomena from a universal microscopic mechanism that occurs on the surface of liquids, independently of mere evaporation. His results have been published in an article in Physical Review Letters, the general Physics review Physical Review Letters, which receives the most citations in the world.

It deals with one of the most common phenomena since the liquid phase appeared in the universe: all liquid, especially when it is in continuous movement like in the sea, always contains gases in a greater or lesser concentration, depending on the pressure and temperature to which it is subjected. Almost always, these gases end up as more or less small bubbles on the surface of the liquid. When these bubbles explode, especially if they are microscopic, minuscule drops are expelled at great velocity, and these drops almost instantly travel notable distances from the surface of the liquid that they came from.


Credit:  University of Seville

These microscopic drops generate the seed of clouds (microscopic grains of salt that form the condensation nuclei of the drops of the clouds) on the surface of the sea, or they can spread all the flavours of a broth in the air independently of its volatility, or form smoke on burning liquids.

The size of these “ghost drops” and their speed are the principle factors that the model designed by Gañán explains and precisely determines, predicting perfectly the results of hundreds of exhaustive experiments carried out from the start of the 20th century until the present day. In accordance with this model, in function of the properties of a determined liquid, there exists a critical size of gas bubble which determines a remarkable singularity: the drop expelled becomes incredibly small, while its speed increases limitlessly at the same time as the size of the bubble shrinks and approaches this limit. Below this limit, no drops are expelled. Specifically, when this size is small enough (as in the case of small bubbles in water), the new model shows that the “ghost” micro-drops can reach supersonic speeds and reach truly meaningful heights.

This finally, and precisely, answers the questions at the beginning of this text. In the particular case of the sea, pollution and waste – which are especially concentrated on the surface, so lessening the surface tension, the principal origin of the problem – the model would explain a drastic decline in the production and size of these “cloud seeds”. If it could be checked, this fact would show us a new pernicious human effect on climate, due to its impact on precipitation.



Contacts and sources:
University of Seville

Citation:  Revision of Bubble Bursting: Universal Scaling Laws of Top Jet Drop Size and Speed Alfonso M. Gañán-Calvo Phys. Rev. Lett. 119, 204502 – Published 16 November 2017
https://doi.org/10.1103/PhysRevLett.119.204502

Copy of Jesus’ Secret Revelations to His Brother Discovered

The first-known original Greek copy of a heretical Christian writing describing Jesus' secret teachings to his brother James has been discovered at Oxford University by biblical scholars at The University of Texas at Austin.

To date, only a small number of texts from the Nag Hammadi library -- a collection of 13 Coptic Gnostic books discovered in 1945 in Upper Egypt -- have been found in Greek, their original language of composition. But earlier this year, UT Austin religious studies scholars Geoffrey Smith and Brent Landau added to the list with their discovery of several fifth- or sixth-century Greek fragments of the First Apocalypse of James, which was thought to have been preserved only in its Coptic translations until now.

"To say that we were excited once we realized what we'd found is an understatement," said Smith, an assistant professor of religious studies. "We never suspected that Greek fragments of the First Apocalypse of James survived from antiquity. But there they were, right in front of us."

A piece of the Coptic translation of the First Apocalypse of James from the Nag Hammadi Codex V.
Image of artifact from the Nag Hammadi Library, Oxford University.


The ancient narrative describes the secret teachings of Jesus to his brother James, in which Jesus reveals information about the heavenly realm and future events, including James' inevitable death.

"The text supplements the biblical account of Jesus' life and ministry by allowing us access to conversations that purportedly took place between Jesus and his brother, James -- secret teachings that allowed James to be a good teacher after Jesus' death," Smith said.

Such apocryphal writings, Smith said, would have fallen outside the canonical boundaries set by Athanasius, Bishop of Alexandria, in his "Easter letter of 367" that defined the 27-book New Testament: "No one may add to them, and nothing may be taken away from them."

With its neat, uniform handwriting and words separated into syllables, the original manuscript was probably a teacher's model used to help students learn to read and write, Smith and Landau said.

"The scribe has divided most of the text into syllables by using mid-dots. Such divisions are very uncommon in ancient manuscripts, but they do show up frequently in manuscripts that were used in educational contexts," said Landau, a lecturer in the UT Austin Department of Religious Studies.

The teacher who produced this manuscript must have "had a particular affinity for the text," Landau said. It does not appear to be a brief excerpt from the text, as was common in school exercises, but rather a complete copy of this forbidden ancient writing.

Smith and Landau announced the discovery at the Society of Biblical Literature Annual Meeting in Boston in November and are working to publish their preliminary findings in the Greco Roman Memoirs series of the Oxyrhynchus Papyri.


Contact and sources:
Rachel Griess
University of Texas Austin

What Adornments Told about the Culture of a Prehistoric People

Vladislav Zhitenev, a Russian archaeologist from  Lomonosov Moscow State University (MSU), studied bone jewelry found at Sungir Upper Paleolithic site. A group led by Vladislav Zhitenev found out that many items were crafted specifically for burial purposes, while others were worn on a daily basis. The style of the jewelry was influenced by many cultures of Europe and the Russian Plain. The article was published in EPAUL 147.

Sungir Upper Paleolithic site is located in Vladimir Region and is dated back to 29,000-31,000 years. Scientist began to study his place over thirty years ago. The encampment of prehistoric hunters includes a burial site of a 40-50 year old man and a grave of two children who died 10-14 years of age. Archaeological excavation revealed over 80 thousand different objects.

"This children's grave contains more adornments and other burial items than any other Upper Paleolithic burial site in Eurasia," - says Vladislav Zhitenev, the author of the study, doctor of historical sciences, and assistant professor of the Archaeology Department of the Faculty of History, MSU. Currently all findings are kept in the State Vladimir-Suzdal Museum Reserve.

This is bone jewelry found at Sungir in the burial of children (1-3) and in the cultural layer (4).
 
Credit: Vladislav Zhitenev

Having studied pendants made from the teeth of Arctic fox, bone beads, and other personal ornaments, scientists found out that these items were worn for a long time as they exhibited rubbing marks and other signs of tear. Other ornaments found at the burials were made in a hurry and don't look so smooth and convenient. Evidently, they were crafted specifically for the burial ceremony. These items include a large horse figurine with a disproportionately short back led. Although the surface of the figurine had been polished, it has a lot of manufacturing and processing marks.

It is still unknown why the grave of children appeared to contain so many objects including worn ones. According to one version, people used the child burial to make a sacrifice to save the community from an adversity of some kind, such as illness or hunger. Burial items were made not only by experienced craftsmen, but by children as well. One of the tusk disks found in the children's grave was made carelessly and unskillfully. It is likely it was crafted by a kid.

Adornments are elements of a non-verbal language used by prehistoric people to tell friends from enemies and to learn about one's social status and standing. By studying personal ornaments scientists learn more about different aspects of intercultural communication in the Upper Paleolithic period.

Vladislav Zhitenev found out that the man and the children lived relatively at the same time separated by several generations at most. This is confirmed by the identical style of peronal ornaments found in their graves. The children were buried at the same time, but the time period between their death and the passing of the man is still unknown. Radiocarbon dating method failed to provide an answer as it is not accurate to the year when applied to such prehistoric specimens. But when radiocarbon dating gives only approximate results, archaeologists turn to implicit data.

"When looking at an item, one can always see a master's hand. Many adornments from the burial sites of the man and the children were crafted in the same way, as if by the same person. Alternatively, this technique could have been passed within the family, say, from father to son or from grandmother to granddaughter," - explains Vladislav Zhitenev. Therefore, the man and the children were separated in time by no more than several dozen years.

Sungir adornments are difficult to classify and include into a certain cultural tradition, as they had been influenced by many cultures. On the one hand, they have a lot in common with the Aurignacian culture that was widely spread in Western and Central Europe in the Early Upper Paleolithic Stone Age. On the other hand, Sungir findings resemble those from some early sites in Kostenki. Finally, all these items are combined with stone objects crafted using a Neanderthal technology, although the remains found in Sungir belonged to Homo sapiens.

Having studied Sungir adornments, scientists found out that a part of them was crafted specifically for the burial ceremony, and another one was worn on a daily basis; the man and the children lived roughly at the same time; and the crafting style was influenced by many cultures including the Aurignacian culture and the culture of the Russian Plain.

In his further studies Vladislav Zhitenev plans to focus on intercultural communication, for example, to find difference between the sites with and without a Neanderthal component.



Contacts and sources:'
Yana Khlyustova 
Lomonosov Moscow State University (MSU)

Wednesday, November 29, 2017

New Interpretation of The Red Queen's Hypothesis: It's about Expansion



In a new publication in the journal Nature, Indre Zliobaite and Mikael Fortelius from the University of Helsinki and Nils Christian Stenseth from the University of Oslo present a new interpretation of one of the classic theories of evolutionary theory, the Red Queen's Hypothesis, proposed by Leigh Van Valen in 1973.

Alice in Wonderland meets the Red Queen

A search for 'Red Queen' on Google Scholar gives over a million hits, reflecting the enormous influence this idea has had and continues to have in a wide sector of science. Its name refers to Lewis Carroll's book Alice Through the Looking Glass, where the Red Queen explains how her country differs from Alice's: "Now, here, you see, it takes all the running you can do, to keep in the same place. If you want to get somewhere else, you must run at least twice as fast as that!"

This is the Red Queen walking randomly.


Credit: Ika Österblad

The half-life of species

Leigh Van Valen originally thought that species should age: the longer a species has been around, the more likely it should be to go extinct. He tried to test this hypothesis on fossil data and found to his surprise that they don't seem to do so - old and young species with similar ways of life (inhabiting the same adaptive zone) have about the same probability to go extinct at any point in time. This is roughly similar to the decay of radioactive nuclei and means that adaptive zones (or in practice the biological groupings that reflect them, such as families and orders) have characteristic half-lives, just as radioactive elements do.

Just over a decade ago, another pattern was discovered in the fossil record of land mammals by Finnish scientists Jukka Jernvall and Mikael Fortelius. This pattern, later described in many other groups as well, has become known as the Hat Pattern, a name drawn from its shape: species and genera typically begin as rare, expand to become more common and widespread, and then contract and go extinct. In most cases there is only a single peak; more than three peaks is quite rare. The Hat Pattern seems to suggest that species and genera past their peak become more likely to go extinct as they age and decline towards extinction, in apparent contradiction to the Law of Constant Extinction.

The road from the top and down - the Hat Pattern

In the new paper, Indre Zliobaite, Mikael Fortelius and Nils Chr. Stenseth propose a new interpretation of the Law of Constant Extinction that focusses on the expansion and peaking of species rather than on their extinction. Supporting their argument by data analysis and simulations, they show that the apparent contradiction is only an illusion and that the Hat Pattern is not only compatible with the Law of Constant Extinction, or perhaps better Law of Constant Peaking, but actually predicted by the Red Queen's Hypothesis.


Credit: University of Helsinki

Of all the scientists in the world, Stenseth and Fortelius are among those who really should have seen this earlier. Both were among the first to write about the 'hat' pattern, and Stenseth has worked on the Red Queen since the 1970s. Although Fortelius hasn't published on the Red Queen, he does have a history of hidden research on the closely related topic, the Law of Constant Extinction. He also participated in a round table meeting on this topic in 2008, convened by Stenseth and featuring Leigh Van Valen himself as a participant. And in the last few years they have again joined forces for a new attempt at this problem, when Fortelius has been a visiting professor at Stenseth's centre of excellence in Oslo.

But the fact is that they didn't. In the end it took the fresh perspective of an outsider to realise that the two theories were connected and actually parts of the same puzzle. Zliobaite, with a background in computer science and credit analysis, who knew that a cessation of growth may signal the impending failure of businesses.

This is assistant professor Indre Zliobaite from the Department of Computer Science, University of Helsinki.


Credit: Susan Heikkinen

Zliobaite was also the one who read with a fresh eye the now almost forgotten theoretical papers where Van Valen further developed his theory, emphasising the expansion of species as the most useful measure of their success. In this perspective, the final extinction emerges as simply the inevitable outcome of the species' failure to expand. Bringing this perspective into the discussion was the key to developing the new, integrated theory.

Quotes:

Zliobaite: "I had no idea that the Red Queen's hypothesis is such a big deal. I thought it is just another research question. Perhaps this allowed me to think about it anew without being burdened by its legacy."

Fortelius: "My job as Kristine Bonnevie Professor during the last three years in Oslo was very much related to the Red Queen. I've been telling people I'm actually there at Her Majesty's secret service."

Stenseth: "The Red Queen's Hypothesis has fascinated me from the very beginning since it, as an evolutionary hypothesis, explicitly brings in ecological interactions to explain large scale evolutionary patterns, such as rate of extinctions."





Contacts and sources:
Assistant Professor Indre Zliobaite, Department of Computer Science,
 Professor Mikael Fortelius, Department of Geosciences and Geography  
University of Helsinki 

Citation: Indre Zliobaite, Mikael Fortelius and Nils Christian Stenseth: Reconciling taxon senescence with the Red Queen's Hypothesis. DOI 10.1038/nature24656 http://www.nature.com

Sea-Level Rise Predicted to Threaten >13,000 Archaeological Sites in Southeastern US

Sea-level rise may impact vast numbers of archaeological and historic sites, cemeteries, and landscapes on the Atlantic and Gulf coasts of the southeastern United States, according to a study published November 29, 2017 in the open-access journal PLOS ONE by David Anderson from the University of Tennessee, Knoxville, USA, and colleagues.

To estimate the impact of sea-level rise on archaeological sites, the authors of the present study analyzed data from the Digital Index of North American Archaeology (DINAA). DINAA aggregates archaeological and historical data sets developed over the past century from numerous sources, providing the public and research communities with a uniquely comprehensive window into human settlement.

Tens of thousands of known archaeological sites are threatened by sea level rise in the southeast, and far more currently unknown and unrecorded, as shown here at low spatial resolution.
Credit: Anderson et al., 2017

Just in the remainder of this century, if projected trends in sea-level rise continue, the researchers predict that over 13,000 recorded archaeological sites in the southeast alone may be submerged with a 1 m rise in sea-level, including over 1,000 listed on the National Register of Historic Places as important cultural properties. Many more sites and structures that have not yet been recorded will also be lost.

Large linked data sets, such as DINAA, that show what may be impacted and what could be lost across entire regions, are essential to developing procedures for sampling, triage, and mitigation efforts. Such research is essential to making accurate forecasts and public policy decisions about the consequences of rapid climate change, extreme weather events, and displaced populations. These are factors that could shape our civilization profoundly in the years to come.

Anderson notes: "Sea-level rise in the coming years will destroy vast numbers of archaeological sites, buildings, cemeteries, and cultural landscapes. Developing informatics capabilities at regional and continental scales like DINAA (Digital Index of North American Archaeology) is essential if we are to effectively plan for, and help mitigate, this loss of human history."


 Contacts and sources:
David Anderson
PLOS

Citation: Anderson DG, Bissett TG, Yerka SJ, Wells JJ, Kansa EC, Kansa SW, et al. (2017) Sea-level rise and archaeological site destruction: An example from the southeastern United States using DINAA (Digital Index of North American Archaeology). PLoS ONE 12(11): e0188142. https://doi.org/10.1371/journal.pone.0188142 http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0188142

First-Of-Its-Kind Mummy Study Reveals Clues to Girl's Story



Who is she, this little mummy girl? Northwestern University scientists and students are working to unravel some of her mysteries, including how her body was prepared 1,900 years ago in Egypt, what items she may have been buried with, the quality of her bones and what material is present in her brain cavity.

As part of a comprehensive scientific investigation, the mummy traveled from Evanston to Argonne National Laboratory on Nov. 27 for an all-day X-ray scattering experiment. It was the first study of its kind performed on a human mummy.

"This is a unique experiment, a 3-D puzzle," said Stuart R. Stock, research professor of cell and molecular biology at Northwestern University Feinberg School of Medicine, who led the synchrotron experiment. "We have some preliminary findings about the various materials, but it will take days before we tighten down the precise answers to our questions. We have confirmed that the shards in the brain cavity are likely solidified pitch, not a crystalline material."

Portrait mummy of a girl, late 1st century CE, mummified remains of 5-year-old girl wrapped in linen, with a portrait in beeswax and pigments on wood. Garrett-Evangelical Theological Seminary, Evanston, Illinois.

Photo courtesy of Northwestern University


The Roman-Egyptian mummy -- which resides at the Garrett-Evangelical Theological Seminary on Northwestern's Evanston campus -- is one of only approximately 100 portrait mummies in the world. These mummies have an extremely lifelike painting of the deceased individual incorporated into the mummy wrappings and placed directly over the person's face. The Romans introduced to Egypt these 2-D portraits of the dead after almost 3,000 years of idealized 3-D images. (Think King Tut).

Just over three feet long, the little girl's body is swaddled in a copious amount of linen. The outermost wrappings have been arranged in an ornate geometric pattern of overlapping rhomboids and also serve to frame the portrait. The face, painted with beeswax and pigment, gazes serenely outward, her dark hair gathered at the back. She is wearing a crimson tunic and gold jewelry.

The study of this rare archeological object, owned by Garrett-Evangelical, is part of an interdisciplinary class at Northwestern focused, in part, on filling out the contextual story of where this mummy came from and who she was.

Thirteen materials science and humanities students are examining the materials and methods used to create both this intact portrait mummy and a well-preserved collection of Roman-Egyptian mummy portraits for an upcoming exhibition at Northwestern's Block Museum of Art. Earlier in the quarter, the class traveled to California to study the portraits at the Phoebe A. Hearst Museum of Anthropology at the University of California, Berkeley, which will loan the portraits to the Block Museum. (Unlike the Garrett mummy, each of these portraits has been separated from its mummy.)

The students already have discovered that the Garrett mummy's portrait was put together in a very different way from the Hearst Museum portraits and likely is from a different workshop. These findings and others yet to come, including results from the synchrotron X-ray study of the Garrett mummy, will culminate in the Block Museum exhibition, "Paint the Eyes Softer: Mummy Portraits from Roman Egypt."

Northwestern University's Stuart Stock and The Art Institute of Chicago's Rachel Sabino discuss the X-ray scattering experiment at Argonne National Laboratory performed Nov. 27 on an 1,900-year-old portrait mummy.

Photo credit Jim Prisching


"Intact portrait mummies are exceedingly rare, and to have one here on campus was revelatory for the class and exhibition," said Marc Walton, a research professor of materials science and engineering at Northwestern's McCormick School of Engineering. He is teaching the fall quarter class with Taco Terpstra, assistant professor of classics and history at the Weinberg College of Arts and Sciences.

The "Paint the Eyes Softer" exhibition will reunite ancient neighbors: the girl portrait mummy is from the site of Hawara, a site close to Tebtunis, where the Hearst Museum's mummy portraits are originally from. The Hawara, or Garrett, mummy is believed to be from a high-status family and was entombed in an underground chamber with four other mummies.

"This is a once-in-a-lifetime opportunity for our undergraduate students -- and for me -- to work at understanding the whole object that is this girl mummy," Walton said. "Today's powerful analytical tools allow us to nondestructively do the archaeology scientists couldn't do 100 years ago."

The synchrotron experiment at Argonne is a modern-day version of 19th-century England's "mummy unwrapping" parties, Walton said. The Northwestern team collaborated with scientists at Argonne and used the extremely brilliant high-energy synchrotron X-rays produced by Argonne's Advanced Photon Source to probe the materials and objects inside the mummy, while leaving the mummy and her wrappings intact.

"From a medical research perspective, I am interested in what we can learn about her bone tissue," Stock said. "We also are investigating a scarab-shaped object, her teeth and what look like wires near the mummy's head and feet."

Prior to its trip to Argonne, the mummy had a CT scan at Northwestern Memorial Hospital in August, also led by Stock. The scan gave the researchers a 3-D map of the structure of the mummy and enabled them to confirm the girl is 5 years old (give or take nine months).


Northwestern University scientists performed an X-ray scattering experiment Nov. 27 at Argonne National Laboratory on a 1,900-year-old portrait mummy -- the first study of its kind.

Photo credit Jim Prisching


At the Advanced Photon Source, Stock and his team shined the pencil-shaped X-ray beam (about twice the diameter of a human hair) on areas of high-density in the mummy that were identified by the CT scan. They now will use the X-ray diffraction patterns as "fingerprints" to identify each crystalline material. For example, is the black rounded object seen on the CT scan a gold object or a rock?

The findings from the synchrotron experiment, CT scan and other scientific analyses and studies of history conducted by the students will help researchers and historians better understand the context in which the Garrett mummy was excavated in 1911 as well as Roman-period mummification practices. Also, conservators will use the information to best preserve the mummy.

"We're basically able to go back to an excavation that happened more than 100 years ago and reconstruct it with our contemporary analysis techniques," Walton said. "All the information we find will help us enrich the entire historic context of this young girl mummy and the Roman period in Egypt."




Contacts and sources:
Megan Fellman 
Northwestern University

Prehistoric Women Had Stronger Arms Than Today's Elite Rowing Crews

A new study comparing the bones of Central European women that lived during the first 6,000 years of farming with those of modern athletes has shown that the average prehistoric agricultural woman had stronger upper arms than living female rowing champions.



Researchers from the University of Cambridge's Department of Archaeology say this physical prowess was likely obtained through tilling soil and harvesting crops by hand, as well as the grinding of grain for as much as five hours a day to make flour.

Until now, bioarchaeological investigations of past behaviour have interpreted women's bones solely through direct comparison to those of men. However, male bones respond to strain in a more visibly dramatic way than female bones.

The Cambridge scientists say this has resulted in the systematic underestimation of the nature and scale of the physical demands borne by women in prehistory.

Cambridge University Women's Boat Club openweight crew rowing during the 2017 Boat Race on the river Thames in London. The Cambridge women's crew beat Oxford in the race. The members of this crew were among those analyzed in the study.

Credit: Alastair Fyfe for the University of Cambridge

"This is the first study to actually compare prehistoric female bones to those of living women," said Dr Alison Macintosh, lead author of the study published today in the journal Science Advances.

"By interpreting women's bones in a female-specific context we can start to see how intensive, variable and laborious their behaviours were, hinting at a hidden history of women's work over thousands of years."

The study, part of the European Research Council-funded ADaPt (Adaption, Dispersals and Phenotype) Project, used a small CT scanner in Cambridge's PAVE laboratory to analyse the arm (humerus) and leg (tibia) bones of living women who engage in a range of physical activity: from runners, rowers and footballers to those with more sedentary lifestyles.

The bones strengths of modern women were compared to those of women from early Neolithic agricultural eras through to farming communities of the Middle Ages.

"It can be easy to forget that bone is a living tissue, one that responds to the rigours we put our bodies through. Physical impact and muscle activity both put strain on bone, called loading. The bone reacts by changing in shape, curvature, thickness and density over time to accommodate repeated strain," said Macintosh.

"By analysing the bone characteristics of living people whose regular physical exertion is known, and comparing them to the characteristics of ancient bones, we can start to interpret the kinds of labour our ancestors were performing in prehistory."

Over three weeks during trial season, Macintosh scanned the limb bones of the Open- and Lightweight squads of the Cambridge University Women's Boat Club, who ended up winning this year's Boat Race and breaking the course record. These women, most in their early twenties, were training twice a day and rowing an average of 120km a week at the time.

The Neolithic women analysed in the study (from 7400-7000 years ago) had similar leg bone strength to modern rowers, but their arm bones were 11-16% stronger for their size than the rowers, and almost 30% stronger than typical Cambridge students.

The loading of the upper limbs was even more dominant in the study's Bronze Age women (from 4300-3500 years ago), who had 9-13% stronger arm bones than the rowers but 12% weaker leg bones.

A possible explanation for this fierce arm strength is the grinding of grain. "We can't say specifically what behaviours were causing the bone loading we found. However, a major activity in early agriculture was converting grain into flour, and this was likely performed by women," said Macintosh.

"For millennia, grain would have been ground by hand between two large stones called a saddle quern. In the few remaining societies that still use saddle querns, women grind grain for up to five hours a day.

"The repetitive arm action of grinding these stones together for hours may have loaded women's arm bones in a similar way to the laborious back-and-forth motion of rowing."

However, Macintosh suspects that women's labour was hardly likely to have been limited to this one behaviour.

"Prior to the invention of the plough, subsistence farming involved manually planting, tilling and harvesting all crops," said Macintosh. "Women were also likely to have been fetching food and water for domestic livestock, processing milk and meat, and converting hides and wool into textiles.

"The variation in bone loading found in prehistoric women suggests that a wide range of behaviours were occurring during early agriculture. In fact, we believe it may be the wide variety of women's work that in part makes it so difficult to identify signatures of any one specific behaviour from their bones."

Dr Jay Stock, senior study author and head of the ADaPt Project, added: "Our findings suggest that for thousands of years, the rigorous manual labour of women was a crucial driver of early farming economies. The research demonstrates what we can learn about the human past through better understanding of human variation today."



Contacts and sources:
Fred Lewsey
University of Cambridge

Do Dogs Possess More Brain Power Than Cats?

There's a new twist to the perennial argument about which is smarter, cats or dogs.

It has to do with their brains, specifically the number of neurons in their cerebral cortex: the "little gray cells" associated with thinking, planning and complex behavior --all considered hallmarks of intelligence.

The first study to actually count the number of cortical neurons in the brains of a number of carnivores, including cats and dogs, has found that dogs possess significantly more of them than cats.



“In this study, we were interested in comparing different species of carnivorans to see how the numbers of neurons in their brains relate to the size of their brains, including a few favorite species including cats and dogs, lions and brown bears,” said Associate Professor of Psychology and Biological Sciences Suzana Herculano-Houzel, who developed the method for accurately measuring the number of neurons in brains.

(Carnivora is a diverse order that consists of 280 species of mammals all of which have teeth and claws that allow them to eat other animals.)

The results of the study are described in a paper titled “Dogs have the most neurons, though not the largest brain: Trade-off between body mass and number of neurons in the cerebral cortex of large carnivoran species” accepted for publication in the open access journal Frontiers in Neuroanatomy.

As far as dogs and cats go, the study found that dogs have about 530 million cortical neurons while cats have about 250 million. (That compares to 16 billion in the human brain.)


Carnivores and their brains.


Credit:   Jeremy Teaford / Vanderbilt 

“I believe the absolute number of neurons an animal has, especially in the cerebral cortex, determines the richness of their internal mental state and their ability to predict what is about to happen in their environment based on past experience,” Herculano-Houzel explained.

“I’m 100 percent a dog person,” she added, “but, with that disclaimer, our findings mean to me that dogs have the biological capability of doing much more complex and flexible things with their lives than cats can. At the least, we now have some biology that people can factor into their discussions about who’s smarter, cats or dogs.”

Herculano-Houzel and her collaborators—graduate students Débora Messeder and Fernanda Pestana from the Universidade Federal do Rio de Janeiro in Brazil; Professor Kelly Lambert at Randolph-Macon College; Associate Professor Stephen Noctor at the University of California, Davis School of Medicine; Professors Abdulaziz Alagaili and Osama Mohammad from King Saud University in Saudi Arabia; and Research Professor Paul R. Manger at the University of the Witwatersrand in South Africa—picked carnivorans to study because of their diversity and large range of brain sizes as well as the fact that they include both domesticated and wild species.


Illustration showing the brains of six carnivores.

Suzana Herculano-Houzel / Vanderbilt

The researchers analyzed the brains of one or two specimens from each of eight carnivoran species: ferret, mongoose, raccoon, cat, dog, hyena, lion and brown bear.

They expected that their measurements would confirm the intuitive hypothesis that the brains of carnivores should have more cortical neurons than the herbivores they prey upon. That is because hunting is more demanding, cognitively speaking, compared to the herbivore’s primary strategy of finding safety in sheer numbers.

However, that proved not to be the case. The researchers determined that the ratio of neurons to brain size in small- and medium-sized carnivores was about the same as that of herbivores, suggesting that there is just as much evolutionary pressure on the herbivores to develop the brain power to escape from predators as there is on carnivores to catch them.

In fact, for the largest carnivorans the neuron-to-brain-size ratio is actually lower. They found that the brain of a golden retriever has more neurons than a hyena, lion or brown bear, even though the bigger predators have brains up to three times as large. The bear is an extreme example. Its brain is 10 times larger than a cat’s, but has about the same number of neurons.

“Meat eating is largely considered a problem-solver in terms of energy, but, in retrospect, it is clear that carnivory must impose a delicate balance between how much brain and body a species can afford,” said Herculano-Houzel.

Hunting requires a lot of energy, particularly for large predators, and the intervals between successful kills are unpredictable. That explains why large meat-eating carnivorans like lions spend most of their time resting and sleeping. In terms of energy, the brain is the most expensive organ in the body and its requirements are proportional to the number of neurons. It also needs energy continuously. As a consequence, the quantity of meat that large hunters can kill and consume and the intermittent nature of feeding appears to limit their brain development.


Suzana Herculano-Houzel with her dog Mielina.

 Courtesy of Herculano-Houzel

The study’s findings also challenge the prevailing view that domesticated animals have smaller brains than their wild cousins. The ratios of brain size to body weight of the domestic species they analyzed—ferret, cat and dog—did not scale in a significantly different manner from those of their wild relatives—mongoose, raccoon, hyena, lion and brown bear.

The analysis also discovered that the raccoon was an outlier—on the brainy side: It packs the same number of cortical neurons as a dog into a brain the size of a cat’s.

“Raccoons are not your typical carnivoran,” said Herculano-Houzel. “They have a fairly small brain but they have as many neurons as you would expect to find in a primate … and that’s a lot of neurons.”

According to the neuroscientist, studying the brains of different species teaches an important lesson: “Diversity is enormous. Not every species is made the same way. Yes, there are recognizable patterns, but there are multiple ways that nature has found of putting brains together—and we’re trying to figure out what difference that makes.”

The study was funded by the James S. McDonnell Foundation; the Schapiro Undergraduate Research Fund at Randolph-Macon College; the Vice Deanship of Research Chairs at the King Saud University; the National Research Foundation of South Africa; and Brazilian crowdfunding contributors.



Contacts and sources:
David F Salisbury
Vanderbilt University

Dogs May Have a Functional Understanding of Emotional Information



Animal behaviour researchers in the UK and Brazil have found that dogs lick their mouths as a response to angry human faces, according to new study.

Scientists examined the behaviour of dogs in response to emotionally significant images and sounds, and found that mouth licking in domestic dogs is not simply a response to food or uncertainty, but appears to be used as a signal to try to communicate with humans in response to visual cues of anger.

Significantly, audio cues of angry human voices did not elicit the same response.

Pictured is a dog in the experiment licking its lips when the image of an angry human is shown, suggest that dogs may have a functional understanding of emotional information.

Credit: Natalia Albuquerque

Dogs were exposed simultaneously to two facial expressions (one positive and one negative from the same individual), which could be either human or canine of either sex, along with a sound, which could be positive or negative from the same species and gender.

The findings, published in the scientific journal Behavioural Processes, shine new light on our understanding of the emotional world of dogs.
The research was conducted by researchers from the University of Sao Paulo, Brazil, and the University of Lincoln, UK.

This video shows a dog licking its lips when the image of an angry female human is shown, suggest that dogs may have a functional understanding of emotional information.

Credit: Natalia Albuquerque

Lead author Natalia Albuquerque from the University of Sao Paulo, said: "Mouth-licking was triggered by visual cues only (facial expressions). There was also a species effect, with dogs mouth-licking more often when looking at humans than at other dogs. Most importantly, the findings indicate that this behaviour is linked to the animals' perception of negative emotions."

The researchers believe that this behavioural trait may have been selected during domestication. The findings, combined with previous evidence of the cognitive processing of emotional expressions, suggest that dogs may have a functional understanding of emotional information and greatly increase our understanding of their emotional world.

Co-author Professor Daniel Mills of the School of Life Sciences at the University of Lincoln, said: "Humans are known to be very visual in both intra and inter-specific interactions, and because the vision of dogs is much poorer than humans, we often tend to think of them using their other senses to make sense of the world. But these results indicate that dogs may be using the visual display of mouth-licking to facilitate dog-human communication in particular."




Contacts and sources:
Natalia Albuquerque
University of Lincoln

Citation:  Mouth-licking by dogs as a response to emotional stimuli Behavioural Processes Volume 146, January 2018, Pages 42-45  \\\

Eruption Clues: Researchers Create Snapshot of Volcano Plumbing

Much like a forensic team recreates a scene to determine how a crime was committed, researchers at the University of New Hampshire are using scientific sleuthing to better understand the journey of magma, or molten rock, in one of Europe’s largest and most active volcanos, Mount Etna. Researchers applied several techniques, in a new way, to create a more accurate picture of the volcano’s plumbing system and how quickly the magma rises to the top to cause an eruption. Their findings contribute to our understanding of how and when volcanoes erupt.

Mount Etna seen from International Space Station

Credit: Chris Hadfield

In their study, recently published in the journal Geochemical Perspective Letters, the UNH team set out to determine if the magma lingers below in pockets of the volcano or if it pushes up all at once. To put the pieces of the puzzle together, they combined three approaches previously not used together to reconstruct the ancient magma plumbing system by looking for chemical signatures in lava rock collected from flows on the surface. They looked at the minerals and the trace elements in the rocks because the tracers can help identify where the minerals have been by how they crystallized.

“As magma moves up through Earth’s crust beneath the volcano, it starts to crystallize,” says Sarah Miller, of UNH’s department of Earth sciences and lead author of the study. “Some elements move rapidly and some more slowly, so there is a chemical record of events in those crystals that can help us determine their journey.”

Extracting the timing and magma source information for ancient volcanism demonstrates how long-lived pre-eruptive processes of transport and storage work at Mount Etna. The researchers found a range of crystallization depths, suggesting there were discrete sites beneath the volcano where the rising magma crystallized. Their chemical forensic work showed two interesting things about the volcano. 

First, the source that produced magma in the ancient Mount Etna is much the same as what happens in Mount Etna in the present-day. Secondly, they showed that the crystals were virtually chemically identical to the lavas in which they erupted. This second finding suggests that in Mount Etna the length of time for crystal storage beneath the volcano is likely relatively short, a result which could help provide insight with recent findings for larger more explosive eruptive systems like Yellowstone.

“This proof-of-concept work puts us in a position to apply our approach more widely to other volcanoes,” said Julie Bryce, professor and chair of Earth sciences and a co-author of this paper. “Our work advances ways we can examine and think about volcanic plumbing systems beneath frequently active volcanic centers. Reconstructing the dynamics of these plumbing systems, and knowing how long-lived they are, helps in anticipating future changes in eruptive potential.”



Contacts and sources:
Robbin Ray
The University of New Hampshire 

Why Is Massive Star Formation Quenched in Galaxy Centers?

A study led by a researcher at the Instituto de Astrofísica de Canarias (IAC) and published this week in Nature Astronomy points to the role of the magnetic field as responsible for decelerating the formation of massive stars in the center of galaxies. Without this process the Big Bang would be questioned.

The current cosmological model to explain our universe, the “Big Bang” model, aims to describe all the phenomena we observe, which includes the galaxies and their evolution from earliest times to the present day. One of the major problems faced by the standard form of this model is that it has predicted a star formation rate –speed at which new stars are born- which is far too big.

Magnetic fields control the collapse of the molecular clouds in the nuclear ring of the galaxy NGC 1097. As a result, formation of massive stars is suppressed in zones of strong magnetic fields (contours).

Credit: Gabriel Pérez, SMM (IAC).

 All the star forming material in galaxies should have been turned into stars when the universe had only a fraction of its present age, 13,8 billion years. However, over half the galaxies we see, mainly the spirals, are very actively forming stars right now. This discrepancy between theoretical prediction and observation has forced to look much more closely at processes which can slow down the rate of star formation during the lifetimes of galaxies, collectively known as “star formation quenching”. Without quenching the standard Big Bang model fails to predict the universe as we know it.

There have been a number of mechanisms proposed for quenching, for example “feedback” from supernovae or active galactic nuclei which breaks up the star forming clouds and reduces the star formation rate, but the measurement and verification of yet other possible processes is of great importance. One of this mechanisms has just been published in Nature Astronomy led by the Instituto de Astrofísica de Canarias (IAC) researcher,Fatemeh Tabatabaei. The study points to magnetic fields and cosmic rays as responsible for massive stars forming slowly.

Studying in great detail the star formation parameters of the central region of the spiral galaxy NGC 1097, they concluded that the presence of a relatively large magnetic field is acting as a quenching agent, due to a magnetic field that exerts a pressure within a gas cloud which can slow down or stop its tendency to collapse and form stars. But the results have gone further, because researchers have shown that this mechanism is in fact working around the center of NGC 1097. They combined observations in the visible and the near infrared from the Hubble Space Telescope with radio observations from the Very Large Array and the Submillimeter Array to explore the effect of the turbulence, stellar radiation, and magnetic field on massive star formation in the galaxy's nuclear ring. This ring contains a number of clearly distinct zones where stars are forming inside huge molecular cloud complexes. The principal result they obtained was an inverse relation between the star formation rate in a given molecular cloud and the magnetic field within it: the larger the field the slower is the star formation rate.



“To do this, we made a specific separation of the magnetic field and its energy from other sources of energy in the interstellar medium, which are the thermal energy, and the general non-thermal but non-magnetic energy” explains Fatemeh Tabatabaei. “Only by combining the high quality observations at very different wavelengths could we do this and when we separated these energy sources the effect of the magnetic field was surprisingly clear”. Almudena Prieto, another of the authors adds in the same sense: “although I have been working on the central zone of NGC 1097 at optical and infrared wavelengths for some time, only when we took into account the magnetic field could we realize its relevance in decreasing the rate at which stars are formed”.

This result has several interesting consequences and throws light on several types of interrelated astrophysical puzzles. Firstly, as the magnetic field does not allow very large molecular clouds to collapse and form stars, star formation can occur only after the clouds break up into smaller clouds. This means that this region will have a higher fraction of low-mass stars than in other zones of the galaxy. The tendency of very massive galaxies to contain a high fraction of low-mass stars at their centers is a recent discovery, and is still in some ways controversial, but is reinforced by the work reported here. Also of interest is the fact that the presence of supermassive black holes in the centers of galaxies does tend to enhance the nuclear magnetic field, so that this quenching mechanism should be most effective in the bulges of galaxies.



Contact:s and sources: 
Fatemeh Tabatabaei
Almudena Prieto
Instituto de Astrofísica de Canarias (IAC)

Citation: “Discovery of massive star formation quenching by non-thermal effects in the center of NGC 1097” por F. S. Tabatabaei et al. Reference: http://rdcu.be/zCQm
DOI: http://dx.doi.org/10.1038/S41550-017-0298-7

Traces of Life on Nearest Exoplanets May Be Hidden in Equatorial Trap

New simulations show that the search for life on other planets may well be more difficult than previously assumed, in research published today in the journal Monthly Notices of the Royal Astronomical Society. The study indicates that unusual air flow patterns could hide atmospheric components from telescopic observations, with direct consequences for formulating the optimal strategy for searching for (oxygen-producing) life such as bacteria or plants on exoplanets.

Current hopes of detecting life on planets outside of our own Solar System rest on examining the planet’s atmosphere to identify chemical compounds that may be produced by living beings. Ozone – a variety of oxygen – is one such molecule, and is seen as one of the possible tracers that may allow us to detect life on another planet from afar.

In Earth's atmosphere, this compound forms the ozone layer that protects us from the Sun's harmful ultraviolet (UV) radiation. On an alien planet, ozone could be one piece in the puzzle that indicates the presence of oxygen-producing bacteria or plants.

Artist's impression of TRAPPIST 1d (right) and its host star TRAPPIST 1 (left). The new research shows how planets like this could hide traces of life from astronomers' observations. C
redit: MPIA Graphics Department. Click for a larger image

But now researchers, led by Ludmila Carone of the Max Planck Institute for Astronomy in Germany, have found that these tracers might be better hidden than we previously thought. Carone and her team considered some of the nearest exoplanets that have the potential to be Earth-like: Proxima b, which is orbiting the star nearest to the Sun (Proxima Centauri), and the most promising of the TRAPPIST-1 family of planets, TRAPPIST-1d.

These are examples of planets that orbit their host star in 25 days or fewer, and as a side effect have one side permanently facing their star, and the other side permanently facing away. Modelling the flow of air within the atmospheres of these planets, Carone and her colleagues found that this unusual day-night divide can have a marked effect on the distribution of ozone across the atmosphere: at least for these planets, the major air flow may lead from the poles to the equator, systematically trapping the ozone in the equatorial region.

Earth's atmosphere has a "transportation belt" of air flows which move ozone from the main production areas near the equator towards the poles. This mechanism is important for creating Earth's global ozone layer
. Credit: L. Carone / MPIA Graphics Department. Click for a larger image

Carone says: “Absence of traces of ozone in future observations does not have to mean there is no oxygen at all. It might be found in different places than on Earth, or it might be very well hidden.”

Such unexpected atmospheric structures may also have consequences for habitability, given that most of the planet would not be protected against UV radiation. “In principle, an exoplanet with an ozone layer that covers only the equatorial region may still be habitable,” Carone explains. “Proxima b and TRAPPIST-1d orbit red dwarfs, reddish stars that emit very little harmful UV light to begin with. On the other hand, these stars can be very temperamental, and prone to violent outbursts of harmful radiation including UV.”

The combination of advances in modelling and much better data from telescopes like the James Webb Space Telescopeis likely to lead to significant progress in this exciting field. “We all knew from the beginning that the hunt for alien life will be a challenge,” says Carone. “As it turns out, we are only just scratching the surface of how difficult it really will be.”




Contacts and sources:
Dr Markus Pössel, Max-Planck-Institut für Astronomie
Dr Morgan Hollis, Royal Astronomical Society
 

Time Between World-Changing Volcanic Super-Eruptions Shorter Than Previously Thought

After analyzing a database of geological records dated within the last 100,000 years, a team of scientists from the University of Bristol has discovered the average time between so-called volcanic super-eruptions is actually much less than previously thought.

Volcanoes and bolides, such as asteroids, are geohazards powerful enough to be destructive on a global scale.

One recent assessment described them as capable of returning humanity to a pre-civilization state.

The largest explosive eruptions are termed 'super-eruptions', and produce in excess of 1,000 gigatons of erupted mass, enough to blanket an entire continent with volcanic ash, and change global weather patterns for decades.

The Toba caldera was the site of a massive super-eruption 75,000 years ago.

Credit: NASA/METI/AIST/Japan Space Systems, and U.S./Japan ASTER Science Team.


The team from the University of Bristol's Schools of Earth Sciences and Mathematics estimated how often the largest explosive eruptions happen. Their analysis indicates that the average time between super-eruptions is only slightly longer than the age of our civilization -- dating from the Agricultural Revolution 12,000 years ago.

Jonathan Rougier, Professor of Statistical Science, said: "The previous estimate, made in 2004, was that super-eruptions occurred on average every 45 - 714 thousand years, comfortably longer than our civilization.

"But in our paper just published, we re-estimate this range as 5.2 - 48 thousand years, with a best guess value of 17 thousand years."

According to geological records, the two most recent super-eruptions were between 20 and 30 thousand years ago.

Professor Rougier added: "On balance, we have been slightly lucky not to experience any super-eruptions since then.

"But it is important to appreciate that the absence of super-eruptions in the last 20 thousand years does not imply that one is overdue. Nature is not that regular.

"What we can say is that volcanoes are more threatening to our civilization than previously thought."

Our civilization will change in unimaginable ways over the next thousand years, and there are many other ways in which it might suffer a catastrophic blow well before the next super-eruption.

On that basis, Professor Rougier says there is little need to plan now for a super-eruption, especially with many other pressing issues to address, which will affect the current and the next generation of humans. But large eruptions, which are much more frequent, can still be devastating for communities and even countries, and careful planning is a crucial part of disaster risk reduction.

Regarding the paper, Professor Rougier explained: "As well as improving our understanding of global volcanism, our paper develops relatively simple techniques to analyse incomplete and error-prone geological and historical records of rare events.

"These difficulties are ubiquitous in geohazards, and we expect our approach will be used for reappraising other types of hazard, such as earthquakes."




Contacts and sources
Shona East
University of Bristol 


Paper: "The global magnitude-frequency relationship for large explosive volcanic eruptions" by J. Rougier, S. Sparks, K. Cashman, and S. Brown, in Earth and Planetary Science Letters.

Tuesday, November 28, 2017

Site of Julius Caesar's Invasion of Britain Discovered

The first evidence for Julius Caesar's invasion of Britain has been discovered by archaeologists from the University of Leicester. The findings will be explored as part of the BBC Four's Digging For Britain on Wednesday 29 November.

Based on new evidence, the team suggests that the first landing of Julius Caesar's fleet in Britain took place in 54BC at Pegwell Bay on the Isle of Thanet, the north--east point of Kent.

This location matches Caesar's own account of his landing in 54 BC, with three clues about the topography of the landing site being consistent with him having landed in Pegwell Bay: its visibility from the sea, the existence of a large open bay, and the presence of higher ground nearby.

Credit: University of Leicester

The project has involved surveys of hillforts that may have been attacked by Caesar, studies in museums of objects that may have been made or buried at the time of the invasions, such as coin hoards, and excavations in Kent.

The University of Leicester project, which is funded by the Leverhulme Trust, was prompted by the discovery of a large defensive ditch in archaeological excavations before a new road was built. The shape of the ditch at Ebbsfleet, a hamlet in Thanet, is very similar to some of the Roman defences at Alésia in France, where the decisive battle in the Gallic War took place in 52 BC.

The site, at Ebbsfleet, on the Isle of Thanet in north-east Kent overlooking Pegwell Bay, is now 900 m inland but at the time of Caesar's invasions it was closer to the coast. The ditch is 4-5 metres wide and 2 metres deep and is dated by pottery and radiocarbon dates to the 1st century BC.

The size, shape, date of the defences at Ebbsfleet and the presence of iron weapons including a Roman pilum (javelin) all suggest that the site at Ebbsfleet was once a Roman base of 1st century BC date.

This is the Ebbsfleet 2016 defensive ditch under excavation.
Credit: University of Leicester

The archaeological team suggest the site may be up to 20 hectares in size and it is thought that the main purpose of the fort was to protect the ships of Caesar's fleet that had been drawn up on to the nearby beach.

Dr Andrew Fitzpatrick, Research Associate from the University of Leicester's School of Archaeology and Ancient History said: "The site at Ebbsfleet lies on a peninsular that projects from the south-eastern tip of the Isle of Thanet. Thanet has never been considered as a possible landing site before because it was separated from the mainland until the Middle Ages.

"However, it is not known how big the Channel that separated it from the mainland (the Wantsum Channel) was. The Wantsum Channel was clearly not a significant barrier to people of Thanet during the Iron Age and it certainly would not have been a major challenge to the engineering capabilities of the Roman army."

Caesar's own account of his landing in 54 BC is consistent with the landing site identified by the team.

This is the Ebbsfleet excavation with Pegwell Bay & Ramsgate.

Credit: University of Leicester

Dr Fitzpatrick explained: "Sailing from somewhere between Boulogne and Calais, Caesar says that at sunrise they saw Britain far away on the left hand side. As they set sail opposite the cliffs of Dover, Caesar can only be describing the white chalk cliffs around Ramsgate which were being illuminated by the rising sun.

"Caesar describes how the ships were left at anchor at an even and open shore and how they were damaged by a great storm. This description is consistent with Pegwell Bay, which today is the largest bay on the east Kent coast and is open and flat. The bay is big enough for the whole Roman army to have landed in the single day that Caesar describes. The 800 ships, even if they landed in waves, would still have needed a landing front 1-2 km wide.

Credit: University of Leicester

"Caesar also describes how the Britons had assembled to oppose the landing but, taken aback by the size of the fleet, they concealed themselves on the higher ground. This is consistent with the higher ground of the Isle of Thanet around Ramsgate.

"These three clues about the topography of the landing site; the presence of cliffs, the existence of a large open bay, and the presence of higher ground nearby, are consistent with the 54 BC landing having been in Pegwell Bay."

The last full study of Caesar's invasions was published over 100 years ago, in 1907.

This is a 3 Lidar model of topography of Thanet showing Ebbsfleet.
Credit: University of Leicester

It has long been believed that because Caesar returned to France the invasions were failures and that because the Romans did not leave a force of occupation the invasions had little or no lasting effects on the peoples of Briton. It has also been believed that because the campaigns were short they will have left few, if any, archaeological remains.

The team challenge this notion by suggesting that in Rome the invasions were seen as a great triumph. The fact that Caesar had crossed the sea and gone beyond the known world caused a sensation. At this time victory was achieved by defeating the enemy in battle, not by occupying their lands.

They also suggest that Caesar's impact in Briton had long-standing effects which were seen almost 100 years later during Claudius's invasion of Briton.

Professor Colin Haselgrove, the principal investigator for the project from the University of Leicester, explained: "It seems likely that the treaties set up by Caesar formed the basis for alliances between Rome and British royal families. This eventually resulted in the leading rulers of south-east England becoming client kings of Rome. Almost 100 years after Caesar, in AD 43 the emperor Claudius invaded Britain. The conquest of south-east England seems to have been rapid, probably because the kings in this region were already allied to Rome.

"This was the beginning of the permanent Roman occupation of Britain, which included Wales and some of Scotland, and lasted for almost 400 years, suggesting that Claudius later exploited Caesar's legacy."

The fieldwork for the project has been carried out by volunteers organised by the Community Archaeologist of Kent County Council who worked in partnership with the University of Leicester. The project was also supported by staff from the University of Leicester Archaeological Services (ULAS).

Kent County Council cabinet member Matthew Balfour said: "The council is delighted to have been able to work in partnership with the University of Leicester to help build on the incredible findings made during our road development. The archaeology of Thanet is very special and we are particularly pleased that such important findings have been made with the involvement of volunteers from the Kent community. When we built the road we ensured that the community played a big part in the archaeological works and it is satisfying to see the legacy of our original work continuing."

Principal Archaeological Officer for Kent County Council Simon Mason, who oversaw the original road excavations carried out by Oxford Wessex Archaeology, said: "Many people do not realise just how rich the archaeology of the Isle of Thanet is. Being so close to the continent, Thanet was the gateway to new ideas, people, trade and invasion from earliest times. This has resulted in a vast and unique buried archaeological landscape with many important discoveries being regularly made. The peoples of Thanet were once witness to some of the earliest and most important events in the nation's history: the Claudian invasion to start the period of Roman rule, the arrival of St Augustine's mission to bring Christianity and the arrival of the Saxons celebrated through the tradition of Hengist and Horsa. It has been fantastic to be part of a project that is helping to bring another fantastic chapter, that of Caesar, to Thanet's story."


Model Roman galley used in invasion of Britain
Credit: Alba Fucens / University of Leicester

Andrew Mayfield said: "The project has been a fantastic opportunity for us to explore the extraordinary archaeology of Thanet alongside the University of Leicester team. Volunteers, both locally from Thanet and further afield in Kent, enthusiastically give up their time and the success of the dig is very much down to their hard work and commitment. We were also lucky to welcome students from both Canterbury Universities, a local branch of the Young Archaeologists Club as well as the local school. This was very much a team effort."

The findings will be explored further as part of the BBC Four's Digging For Britain. The East episode, in which the Ebbsfleet site appears, will be the second programme in the series, and will be broadcast on Wednesday 29 November 2017.



Contacts and sources:
Dr Andrew Fitzpatrick
University of Leicester

Beating Heart Patch is Large Enough to Repair an Adult Heart

Biomedical engineers at Duke University have created a fully functioning artificial human heart muscle large enough to patch over damage typically seen in patients who have suffered a heart attack. The advance takes a major step toward the end goal of repairing dead heart muscle in human patients.

The study appears online in Nature Communications on November 28, 2017.

"Right now, virtually all existing therapies are aimed at reducing the symptoms from the damage that's already been done to the heart, but no approaches have been able to replace the muscle that's lost, because once it's dead, it does not grow back on its own," said Ilia Shadrin, a biomedical engineering doctoral student at Duke University and first author on the study. "This is a way that we could replace lost muscle with tissue made outside the body."



Unlike some human organs, the heart cannot regenerate itself after a heart attack. The dead muscle is often replaced by scar tissue that can no longer transmit electrical signals or contract, both of which are necessary for smooth and forceful heartbeats.

The end result is a disease commonly referred to as heart failure that affects over 12 million patients worldwide. New therapies, such as the one being developed by Shadrin and his advisor Nenad Bursac, professor of biomedical engineering at Duke, are needed to prevent heart failure and its lethal complications.

Current clinical trials are testing the tactic of injecting stem cells derived from bone marrow, blood or the heart itself directly into the affected site in an attempt to replenish some of the damaged muscle. While there do seem to be some positive effects from these treatments, their mechanisms are not fully understood. Fewer than one percent of the injected cells survive and remain in the heart, and even fewer become cardiac muscle cells.

Heart patches, on the other hand, could conceivably be implanted over the dead muscle and remain active for a long time, providing more strength for contractions and a smooth path for the heart's electrical signals to travel through. These patches also secrete enzymes and growth factors that could help recovery of damaged tissue that hasn't yet died.

Credit: Duke University
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For this approach to work, however, a heart patch must be large enough to cover the affected tissue. It must also be just as strong and electrically active as the native heart tissue, or else the discrepancy could cause deadly arrhythmias.

This is the first human heart patch to meet both criteria. "Creating individual cardiac muscle cells is pretty commonplace, but people have been focused on growing miniature tissues for drug development," said Bursac. "Scaling it up to this size is something that has never been done and it required a lot of engineering ingenuity."

The cells for the heart patch are grown from human pluripotent stem cells -- the cells that can become any type of cell in the body. Bursac and Shadrin have successfully made patches using many different lines of human stem cells, including those derived from embryos and those artificially forced or "induced" into their pluripotent state.

Various types of heart cells can be grown from these stem cells: cardiomyocytes, the cells responsible for muscle contraction; fibroblasts, the cells that provide structural framework for heart tissue; and endothelial and smooth muscle cells, the cells that form blood vessels. The researchers place these cells at specific ratios into a jelly-like substance where they self-organize and grow into functioning tissue.

Finding the right combination of cells, support structures, growth factors, nutrients and culture conditions to grow large, fully functional patches of human heart tissue has taken the team years of work. Every container and procedure had to be sized up and engineered from scratch. And the key that brought it all together was a little bit of rocking and swaying.

"It turns out that rocking the samples to bathe and splash them to improve nutrient delivery is extremely important," said Shadrin. "We obtained three-to-five times better results with the rocking cultures compared to our static samples."

The results improved on the researchers' previous patches, which were one square centimeter and four square centimeters. They successfully scaled up to 16 square centimeters and five to eight cells thick. Tests show that the heart muscle in the patch is fully functional, with electrical, mechanical and structural properties that resemble those of a normal, healthy adult heart.

"This is extremely difficult to do, as the larger the tissue that is grown, the harder it is to maintain the same properties throughout it," said Bursac. "Equally challenging has been making the tissues mature to adult strength on a fast timescale of five weeks while achieving properties that typically take years of normal human development."

Bursac and Shadrin have already shown that these cardiac patches survive, become vascularized and maintain their function when implanted onto mouse and rat hearts. For a heart patch to ever actually replace the work of dead cardiac muscle in human patients, however, it would need to be much thicker than the tissue grown in this study. And for patches to be grown that thick, they need to be vascularized so that cells on the interior can receive enough oxygen and nutrients. Even then, researchers would have to figure out how to fully integrate the heart patch with the existing muscle.

"Full integration like that is really important, not just to improve the heart's mechanical pumping, but to ensure the smooth spread of electrical waves and minimize the risk of arrhythmias," said Shadrin.

"We are actively working on that, as are others, but for now, we are thrilled to have the 'size matters' part figured out," added Bursac.

The research is part of a seven-year, $8.6 million grant from the National Institutes of Health. With the large heart patches in hand, the Bursac team is collaborating with researchers at the University of Alabama at Birmingham to develop procedures to successfully integrate the patch onto the hearts of pigs. Another affiliated team of researchers at the University of Wisconsin-Madison is working to develop improved stem cells for creating the main cell types that compose these heart patches, in the hopes of minimizing an immune response to the delivery of the engineered tissues.

This research was supported by Foundation Leducq and the National Institutes of Health (R01HL104326, R01HL12652, UG3TR002142, U01HL134764, 5T32GM007171, F30HL122079).



Contacts and sources:
Ken Kingery
Duke University

Citation: "Cardiopatch platform enables maturation and scale-up of human pluripotent stem cell-derived engineered heart tissues," Ilya Y. Shadrin, Brian W. Allen, Ying Qian, Christopher P. Jackman, Aaron L. Carlson, Mark E. Juhas, and Nenad Bursac. Nature Communications, 2017. DOI: 10.1038/s41467-017-01946-x http://dx.doi.org/10.1038/s41467-017-01946-x

Synthetic Biology and Chemistry Combine to Create New Antibiotics

Combining the innovations of synthetic biology with biology and chemistry, a team of scientists at the University of Bristol have generated a brand-new platform that will allow the production of desperately needed brand-new antibiotics.

With resistance growing to existing antibiotics, there is a vital and urgent need for the discovery and development of new antibiotics that are cost effective.

Promising developments are derivatives of the antibiotic pleuromutilin, with the core pleuromutilin isolated from the mushroom Clitopilus passeckerianus.

Pleuromutilin derivatives are potent antibacterial drugs but often require difficult chemical modifications.

Fruiting bodies from the mushroom Clitopilus passeckerianus generated in the laboratory
Credit: University of Bristol

In a new paper published today in Nature Communications, the Bristol team report the genetic characterisation of the steps involved in pleuromutilin biosynthesis through heterologous expression and generate a semi-synthetic pleuromutilin derivative with enhanced antibiotic activity.

This was achieved by taking the complete genetic pathway for pleuromutilin production, containing seven genes, from the mushroom, and rebuilding it in the industrially useful filamentous fungus Aspergillus oryzae, traditionally used to make soy sauce.

This then generated a unique platform of Aspergillus lines with combinations of the pathway genes to allow new compounds to be synthesized.

Professor Chris Willis, from the School of Chemistry, said: “This is a classic case where nature has produced something really useful, but combining nature with chemistry through a synthetic biology approach we are able to make things even better.”

These new compounds are some of the only new class of antibiotics to join the market recently as human therapeutics.

Furthermore, with their novel mode of action and lack of cross-resistance, pleuromutilins and their derivatives represent a class with further great potential, particularly for treating resistant strains such as methicillin-resistant Staphylococcus aureus (MRSA) and extensively drug resistant tuberculosis (XTB).

Professor Gary Foster from the School of Biological Sciences who led the team, with Dr Andy Bailey, added: “This research is very exciting as it also paves the way for future characterization of biosynthetic pathways of other basidiomycete natural products in ascomycete heterologous hosts.

“Many mushrooms have never even been examined and act as an untapped resource.

“The platform also opens up new possibilities of further chemical modification for the growing class of potent antibiotics.”





Contacts and sources:
Gary Foster
University of Bristol

Paper: ‘Heterologous expression reveals the biosynthesis of the antibiotic pleuromutilin and generates novel bioactive semi-synthetic derivatives’ by F. Alberti, K. Khairudin, E. Rodriguez Venegas, J. Davies, Patrick. Hayes, C. Willis, A. Bailey and G. Foster in Nature Communications