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Wednesday, November 30, 2016

Eye Surgery Of The Future: Gentle, Efficient, Out-Patient Surgery

The eye surgery of the future will be performed on an out-patient basis, will be gentle and efficient. "Our vision for the future is an eye clinic with no beds," says Ursula Schmidt-Erfurth, Head of the Department of Ophthalmology and Optometrics, speaking at a press conference prior to the ART 2016 specialist conference (Advanced Retinal Therapy), taking place in Vienna this coming Saturday.

Gentle out-patient treatment means that it is pain-free, non-invasive, does not require anaesthesia and only involves a short stay in a day clinic. "This is efficient for the doctors, the patients, who can go straight home – and for the health system, because it is extremely cost saving," says Schmidt-Erfurth, in summary.

Advanced Retinal Therapy conference "ART 2016" in Vienna on 3 December 
Image: Fotolia

For many years now, cataract operations have been done on a day-surgery basis and now the last bastion of complex eye surgery is also about to take this revolutionary step. There is lively debate among the scientific ophthalmology community as to whether an eye hospital still needs patient beds and whether the standard follow-up examinations following major eye procedures are even necessary. Schmidt-Erfurth: "Colleagues in the USA are already performing major retinal procedures in the ophthalmologist’s office rather than in hospitals."

New approaches for more efficient eye surgery

As in many other areas of medicine, new technological advances have fundamentally changed the operating techniques used in retinal surgery. For example, hitherto relevant paradigms such as keeping patients face down for days with a gas tamponade in their eye or the procedure for pathological membranes on the macula, which can greatly affect patients' vision, are now the subject of controversial debate.

As MedUni Vienna experts Schmidt-Erfurth, Rupert Menapace and Michael Georgopoulos explained on Wednesday in Vienna, the international trend in retinal surgery is moving towards the use of microscopically thin endoscopes and establishing the use of digital imaging in vitreoretinal surgery. “Having real-time virtual images of the wafer-thin retina during the operation and being able to identify discrete pathological changes, enables us to perform much more careful, gentle and efficient eye surgery," explains Michael Georgopoulos, a surgeon at MedUni Vienna’s Department of Ophthalmology and Optometrics.

Further improvement is possible through the use of ultra-modern femtosecond laser technology, which MedUni Vienna's ophthalmology department has had at its disposal for two years now, in the form of a mobile unit with low-level laser technology. This allows highly accurate incisions to be made according to an individually tailored treatment plan: this means that, in a cataract operation, the corneal incision, capulostomy and fragmentation of the clouded lens content can be done accurately and in an absolutely reproducible manner. Schmidt-Erfurth: "This helps to further improve uncorrected visual acuity and to avoid potential re-clouding." It also allows simultaneous correction of corneal curvature by making corneal relaxing incisions with a precision that has not previously been possible.

Contacts and sources:

Man-Made Noise Can Affect How Animals Use Information From Scents

Research by scientists at the University of Bristol has, for the first time, found that man-made noise can have a detrimental impact on an animal’s use of scent – putting them at greater risk of being attacked by predators.

Using field-based experimental trials on dwarf mongooses in South Africa, the researchers combined sound recordings and faecal samples to demonstrate that road-noise playback negatively affected the mongooses' ability to detect predator faeces. Even after detection, the additional noise led to less information gathering and less vigilance, making the mongooses more vulnerable to danger.

Professor Andy Radford from the School of Biological Sciences said: "We've known for a long time that noise from urbanisation, traffic and airports can detrimentally affect humans by causing stress, sleep deprivation, cardiac problems and slower learning. What’s becoming increasingly clear is that a lot of other species – mammals, birds, fish, insects and amphibians – are also impacted in all sorts of ways by anthropogenic, or man-made, noise."

Two dwarf mongooses who took part in the experiment

Credit: Shannon Benson

One obvious way in which man-made noise can cause animals problems is through the masking of valuable acoustic information. Lead author Amy Morris-Drake says: "What our study shows for the first time is that there could also be disruption to the use of olfactory information; man-made noise could affect decision-making based on information gathered using a different sense."

The Bristol team's experiment used groups of wild dwarf mongooses that were so familiar with the researchers’ close presence that they could walk within a few feet of them. Co-author Dr Julie Kern adds: "This habituation allows us to conduct ecologically relevant experiments in the mongooses' natural habitat while collecting incredibly detailed and accurate information."

Closely monitoring the mongooses, the team found that their adaptive responses to predatory cues, such as increased inspection of the cue, vigilance scanning for danger and more time spent near the safety of the burrow, were all disrupted by road-traffic noise.

Morris-Drake said: "While lots of work on the impacts of man-made noise has shown effects on animal vocalisations, movement patterns and foraging, it is often difficult to determine what that might mean for survival or reproductive success. By looking at responses to cues about a predator’s presence, there is a direct link to survival; making the wrong decision can result in death."

Professor Radford concluded: "Our study suggests that noise pollution can have a negative effect in terms of information use – in this case the impact on responses to smell, a very common information source in mammals. Given the demonstrated effects, considering the interactions among multiple sensory channels is critically important if we are to understand fully the consequences of human-induced environmental change." 

Contacts and sources:

‘Cross-modal impacts of anthropogenic noise on information use’ by Amy Morris-Drake, Julie M. Kern and Andrew N. Radford in Current Biology.

Free Big History Massive Open Online Course from the Big Bang to Now From the University of Amersterdam

On 28 November, the University of Amsterdam’s Institute for Interdisciplinary Studies (ISS) launched the Big History Massive Open Online Course (MOOC) on the Coursera, YouTube and ChronoZoom platforms. The MOOC, which has been established with the assistance of a grant from the Dutch Ministry of Education, is freely available in all countries.

In this academic MOOC, 20 prominent researchers, from astronomers to historians, will give an integrated overview of the history of everything, from the Big Bang to now.

The MOOC takes approximately 4 weeks on Coursera, but the parts will also be offered separately on YouTube and via the virtual zoomable timeline ChronoZoom. As a result, it is possible to integrate the content oneself into one’s own education. In this way, the MOOC Big History provides context to the various disciplines that are reviewed within this subject.

A better understanding of history

Esther Quaedackers, big history lecturer at the UvA and coordinator of the MOOC: 'This Big History MOOC brings together 20 top researchers from various disciplines in one course, serving as a beautiful, accessible introduction to better understanding history from the Big Bang up until life on earth as it is today.'

Lucy Wenting, Director of the IIS: 'With the help of the MOOC, the UvA is aiming, as a pioneer in the field of big history, to meet the fast-growing global demand for big history education. By offering this on different platforms, such as YouTube and ChronoZoom, it offers anyone the opportunity to use the material, and to expand or modernise their education.'


If you would you like to register for this MOOC, please visit www.iis.uva.nl/moocbighistory and select one of the different platforms on which this MOOC is offered.

ICT in teaching and education
The UvA is developing various initiatives in the field of ICT in education. An increasing amount of lectures can be viewed online – via livestream or afterwards. The development of and experimentation with MOOCs is in keeping with the drive to make knowledge broadly available and to demonstrate the attractiveness of a scientific study.

Contacts and sources:
University of Amsterdam’s Institute for Interdisciplinary Studies (ISS)

First Signs of Weird Quantum Property of Empty Space?

VLT observations of neutron star may confirm 80-year-old prediction about the vacuum

By studying the light emitted from an extraordinarily dense and strongly magnetised neutron star using ESO’s Very Large Telescope, astronomers may have found the first observational indications of a strange quantum effect, first predicted in the 1930s. The polarisation of the observed light suggests that the empty space around the neutron star is subject to a quantum effect known as vacuum birefringence.

This artist’s view shows how the light coming from the surface of a strongly magnetic neutron star (left) becomes linearly polarised as it travels through the vacuum of space close to the star on its way to the observer on Earth (right). The polarisation of the observed light in the extremely strong magnetic field suggests that the empty space around the neutron star is subject to a quantum effect known as vacuum birefringence, a prediction of quantum electrodynamics (QED). 

The magnetic and electric field directions of the light rays are shown by the red and blue lines. Model simulations by Roberto Taverna (University of Padua, Italy) and Denis Gonzalez Caniulef (UCL/MSSL, UK) show how these align along a preferred direction as the light passes through the region around the neutron star. As they become aligned the light becomes polarised, and this polarisation can be detected by sensitive instruments on Earth. 
Credit: ESO/L. Calçada

A team led by Roberto Mignani from INAF Milan (Italy) and from the University of Zielona Gora (Poland), used ESO’s Very Large Telescope (VLT) at the Paranal Observatory in Chile to observe the neutron star  RX J1856.5-3754, about 400 light-years from Earth [1].

Despite being amongst the closest neutron stars, its extreme dimness meant the astronomers could only observe the star with visible light using the FORS2  instrument on the VLT, at the limits of current telescope technology.

This wide field image shows the sky around the very faint neutron star RX J1856.5-3754 in the southern constellation of Corona Australis. This part of the sky also contains interesting regions of dark and bright nebulosity surrounding the variable star R Coronae Australis (upper left), as well as the globular star cluster NGC 6723. The neutron star itself is too faint to be seen here, but lies very close to the centre of the image.

Credit: ESO/Digitized Sky Survey 2 Acknowledgement: Davide De Martin

Neutron stars are the very dense remnant cores of massive stars — at least 10 times more massive than our Sun — that have exploded as supernovae at the ends of their lives. They also have extreme magnetic fields, billions of times stronger than that of the Sun, that permeate their outer surface and surroundings.

This artist’s view shows how the light coming from the surface of a strongly magnetic neutron star (left) becomes linearly polarized as it travels through the vacuum of space close to the star on its way to the observer on Earth (right). The polarization of the observed light in the extremely strong magnetic field suggests that the empty space around the neutron star is subject to a quantum effect known as vacuum birefringence, a prediction of quantum electrodynamics (QED). This effect was predicted in the 1930s but has not been observed before.

The magnetic and electric field directions of the light rays are shown by the red and blue lines. Model simulations by Roberto Taverna (University of Padua, Italy) and Denis Gonzalez Caniulef (UCL/MSSL, UK) show how these align along a preferred direction as the light passes through the region around the neutron star. As they become aligned the light becomes polarised, and this polarisation can be detected by sensitive instruments on Earth.

Credit: ESO/L. Calçada

These fields are so strong that they even affect the properties of the empty space around the star. Normally a vacuum is thought of as completely empty, and light can travel through it without being changed. But in quantum electrodynamics (https://en.wikipedia.org/wiki/Quantum_electrodynamics) (QED), the quantum theory describing the interaction between photons and charged particles such as electrons, space is full of virtual particles that appear and vanish all the time. Very strong magnetic fields can modify this space so that it affects the polarisation of light passing through it.

Mignani explains: “According to QED, a highly magnetised vacuum behaves as a prism for the propagation of light, an effect known as vacuum birefringence.”

Among the many predictions of QED, however, vacuum birefringence (https://en.wikipedia.org/wiki/Vacuum_polarization) so far lacked a direct experimental demonstration. Attempts to detect it in the laboratory have not yet succeeded in the 80 years since it was predicted in a paper by Werner Heisenberg (https://en.wikipedia.org/wiki/Werner_Heisenberg) (of uncertainty principle (https://en.wikipedia.org/wiki/Uncertainty_principle fame)) and Hans Heinrich Euler (https://en.wikipedia.org/wiki/Hans_Heinrich_Euler).

"This effect can be detected only in the presence of enormously strong magnetic fields, such as those around neutron stars. This shows, once more, that neutron stars are invaluable laboratories in which to study the fundamental laws of nature." says Roberto Turolla (University of Padua, Italy).

After careful analysis of the VLT data, Mignani and his team detected linear polarisation ) — at a significant degree of around 16% — that they say is likely due to the boosting effect of vacuum birefringence  occurring in the area of empty space surrounding RX J1856.5-3754 [2].

Vincenzo Testa (INAF, Rome, Italy) comments: "This is the faintest object for which polarisation has ever been measured. It required one of the largest and most efficient telescopes in the world, the VLT, and accurate data analysis techniques to enhance the signal from such a faint star."

Colour composite photo of the sky field around the lonely neutron star RX J1856.5-3754 and the related cone-shaped nebula. It is based on a series of exposures obtained with the multi-mode FORS2 instrument at VLT KUEYEN through three different optical filters. The trail of an asteroid is seen in the field with intermittent blue, green and red colours. RX J1856.5-3754 is exactly in the centre of the image.

Credit: ESO

"The high linear polarization that we measured with the VLT can’t be easily explained by our models unless the vacuum birefringence effects predicted by QED are included," adds Mignani.

This video sequence takes us from a broad view of the spectacular central regions of the Milky Way deep into the small constellation of Corona Australis. Here, as well as seeing clouds of glowing gas and dark regions of dust, we find the very faint neutron star RX J1856.5-3754. This extremely dense and magnetic object is the first place that indications of a strange quantum effect called vacuum birefringence may have been detected in new observations made using ESO’s Very Large Telescope.

Credit: ESO/N. Risinger (skysurvey.org)/Digitized Sky Survey 2

"This VLT study is the very first observational support for predictions of these kinds of QED effects arising in extremely strong magnetic fields," remarks Silvia Zane (UCL/MSSL, UK).

Mignani is excited about further improvements to this area of study that could come about with more advanced telescopes: “Polarisation measurements with the next generation of telescopes, such as ESO’s European Extremely Large Telescope (http://eso.org/e-elt) , could play a crucial role in testing QED predictions of vacuum birefringence effects around many more neutron stars.”

"This measurement, made for the first time now in visible light, also paves the way to similar measurements to be carried out at X-ray wavelengths," adds Kinwah Wu (UCL/MSSL, UK).

Contacts and sources: 
Roberto Mignani, INAF - Istituto di Astrofisica Spaziale e Fisica Cosmica Milano
Vincenzo Testa. INAF - Osservatorio Astronomico di Roma
Roberto Turolla, University of Padova
Richard Hook, European Southern Observatory - ESO

Earth’s ‘Technosphere’ Now Weighs 30 Trillion Tons

The planet’s technosphere now weighs some 30 trillion tons – a mass of more than 50 kilos for every square metre of the Earth’s surface

Numbers of technofossil ‘species’ now outnumber numbers of biotic species on planet Earth
Technosphere includes physical human-made structures such as houses, factories, smartphones, computers and landfill

“The technosphere is a major new phenomenon of this planet – and one that is evolving extraordinarily rapidly” – Professor Mark Williams, University of Leicester

Credit: University of Leicester

An international team led by University of Leicester geologists has made the first estimate of the sheer size of the physical structure of the planet’s technosphere – suggesting that its mass approximates to an enormous 30 trillion tons.

The technosphere is comprised of all of the structures that humans have constructed to keep them alive on the planet – from houses, factories and farms to computer systems, smartphones and CDs, to the waste in landfills and spoil heaps.

In a new paper published in the journal The Anthropocene Review, Professors Jan Zalasiewicz, Mark Williams and Colin Waters from the University of Leicester Department of Geology led an international team suggesting that the bulk of the planet’s technosphere is staggering in scale, with some 30 trillion tons representing a mass of more than 50 kilos for every square metre of the Earth’s surface.

Professor Zalasiewicz explained: “The technosphere is the brainchild of the USA scientist Peter Haff – also one of the co-authors of this paper. It is all of the structures that humans have constructed to keep them alive, in very large numbers now, on the planet: houses, factories, farms, mines, roads, airports and shipping ports, computer systems, together with its discarded waste.

“Humans and human organisations form part of it, too – although we are not always as much in control as we think we are, as the technosphere is a system, with its own dynamics and energy flows – and humans have to help keep it going to survive.”

The Anthropocene concept – a proposed epoch highlighting the impact humans have made to the planet - has provided an understanding that humans have greatly changed the Earth.

Professor Williams said: “The technosphere can be said to have budded off the biosphere and arguably is now at least partly parasitic on it. At its current scale the technosphere is a major new phenomenon of this planet – and one that is evolving extraordinarily rapidly.

“Compared with the biosphere, though, it is remarkably poor at recycling its own materials, as our burgeoning landfill sites show. This might be a barrier to its further success – or halt it altogether.”

The researchers believe the technosphere is some measure of the extent to which we have reshaped our planet.

“There is more to the technosphere than just its mass,” observes Professor Waters. “It has enabled the production of an enormous array of material objects, from simple tools and coins, to ballpoint pens, books and CDs, to the most sophisticated computers and smartphones. Many of these, if entombed in strata, can be preserved into the distant geological future as ‘technofossils’ that will help characterize and date the Anthropocene.”

If technofossils were to be classified as palaeontologists classify normal fossils - based on their shape, form and texture – the study suggests that the number of individual types of ‘technofossil’ now on the planet likely reaches a billion or more – thus far outnumbering the numbers of biotic species now living.

The research suggests the technosphere is another measure of the extraordinary human-driven changes that are affecting the Earth.

Professor Zalasiewicz added: “The technosphere may be geologically young, but it is evolving with furious speed, and it has already left a deep imprint on our planet.”

The research is associated with the major new project of Berlin’s Haus der Kulturen der Welt on the technosphere. More information about the project is available here:

The paper is part of a forthcoming special issue that explores various aspects of the technosphere concept, and that is edited by Sara Nelson, Christoph Rosol and Jürgen Renn, all of the Max Planck Institute for the History of Science, Berlin.

Contacts and sources:
University of Leicester

 The paper ‘Scale and diversity of the physical technosphere: A geological perspective’ is published in The Anthropocene Review / DOI: 10.1177/2053019616677743 and is available here: http://anr.sagepub.com/content/early/2016/11/25/2053019616677743.full.pdf+html

Technion Researchers Create First “Water-Wave” Laser

Technion researchers have demonstrated, for the first time, that laser emissions can be created through the interaction of light and water waves. This “water-wave laser” could someday be used in tiny sensors that combine light waves, sound and water waves, or as a feature on microfluidic “lab-on-a-chip” devices used to study cell biology and to test new drug therapies.

For now, the water-wave laser offers a “playground” for scientists studying the interaction of light and fluid at a scale smaller than the width of a human hair, the researchers write in the new report, published November 21 in Nature Photonics.

Artist impression
Credit: Technion 

The study was conducted by Technion-Israel Institute of Technology students Shmuel Kaminski, Leopoldo Martin, and Shai Maayani, under the supervision of Professor Tal Carmon, head of the Optomechanics Center at the Mechanical Engineering Faculty at Technion. Carmon said the study is the first bridge between two areas of research that were previously considered unrelated to one another: nonlinear optics and water waves.

A typical laser can be created when the electrons in atoms become “excited” by energy absorbed from an outside source, causing them to emit radiation in the form of laser light. Professor Carmon and his colleagues now show for the first time that water wave oscillations within a liquid device can also generate laser radiation.

The possibility of creating a laser through the interaction of light with water waves has not been examined, Carmon said, mainly due to the huge difference between the low frequency of water waves on the surface of a liquid (approximately 1,000 oscillations per second) and the high frequency of light wave oscillations (1014 oscillations per second). This frequency difference reduces the efficiency of the energy transfer between light and water waves, which is needed to produce the laser emission.

Graduate student Shai Maayani and Professor Tal Carmon

Credit: Technion 

To compensate for this low efficiency, the researchers created a device in which an optical fiber delivers light into a tiny droplet of octane and water. Light waves and water waves pass through each other many times (approximately one million times) inside the droplet, generating the energy that leaves the droplet as the emission of the water-wave laser.

The interaction between the fiber optic light and the miniscule vibrations on the surface of the droplet are like an echo, the researchers noted, where the interaction of sound waves and the surface they pass through can make a single scream audible several times. In order to increase this echo effect in their device, the researchers used highly transparent, runny liquids, to encourage light and droplet interactions.

Furthermore, a drop of water is a million times softer than the materials used in current laser technology. The minute pressure applied by light can therefore cause droplet deformation that is a million times greater than in a typical optomechanical device, which may offer greater control of the laser’s emissions and capabilities, the Technion scientists said.

Contacts and sources: 

To the Paper in Nature Photonics

Acoustics Stop Damaging Coconut Rhinoceros Beetles

What would the paradise of Hawaii be without swaying coconut palms, with succulent fruit that is almost synonymous with the tropical island? Unfortunately, that may be the future of the island unless scientists find some way to stop the destructive Coconut Rhinoceros Beetle which feeds on the coconut palms, stripping them of their leaves and decimating the vegetation. A team of researchers at the University of Hawaii in Honolulu are using acoustics to help to understand this beetle, its habits and movements in order to protect the state’s valuable natural resources.

Coconut Rhinoceros Beetle 

  Credit: USDA

The Coconut Rhino Beetle is an invasive species that has plagued Hawaii since 2013. The goal of the state of Hawaii, with funding from the U.S. Department of Agriculture, is to eradicate the beetle before its devastating effects on the state's palm trees reach the level of destruction Guam experienced, where the trees were stripped of their leaves and significant amounts of vegetation were lost. The beetle has few known predators in Hawaii and the impacts on the agricultural and tourism industries to Hawaii could be devastating if left unmitigated.

It may not seem as though tracking and finding black beetles that can grow to three inches in length would be a challenge. But these beetles migrate only at night and finding a way to track their movement is critical.

“Stridulation, or chirping, sounds produced by the beetles have been reported with respect to mating and aggressive male behavior, and while previous studies proposed the mechanism and reported on some preliminary acoustic recording of the chirps, the chirp characteristics have not been examined extensively,” explained John Allen, a scientist at the University of Hawaii.

During the 172nd Meeting of the Acoustical Society of America and the 5th Joint Meeting with Acoustical Society of Japan, being held Nov. 28-Dec. 2, 2016, in Honolulu, Hawaii, Allen explained how the team expanded on previous work, combining acoustical, high speed optical and infrared camera measurements to determine mechanisms of sound generation for adult male and female beetles, as well as larvae, during their different stages of development. This kind of information could prove invaluable for tracking and mitigating the beetles’ migration.

"Obtaining a sufficient number of recordings for individual beetles has been difficult and we developed a triggering method for long-term recording from beetle movement or flight take-off," said Allen. "Field collection of acoustic data is also challenging since the beetles fly only at night and the sound is hard to detect above the ambient background noise."

Researchers are hopeful that they will be able to use acoustics to track the movement of beetles since other methods, such as optical, have had limited success.

“Since this beetle is more massive than other species, the acoustic frequency is less likely to be confused with [that of] other species,” said Allen. “We may be able to use passive detection using long term acoustic microphone recorders by characterizing their chirp signatures.”

In taking and analyzing data, the team revealed a novel harmonic structure not previously reported, and were able to create a spectrogram of a distress chirp. The chirps, and harmonics that appear, can indicate different behaviors ranging from distress to aggression. Whether this information can be used in tracking or anticipating beetle movement or behavior remains to be seen.


Contacts and sources
 Acoustical Society of America (ASA)

Presentation 2pABa4, "Time frequency analysis of the coconut rhinoceros beetle chirps," by John S. Allen is at 1:45 p.m. HAST, Nov. 29, 2016 in Room Coral 2.

Study Explains Evolution Phenomenon That Puzzled Darwin

Why do some animals have extravagant, showy ornaments -- think elk and deer antlers, peacock feathers and horns on dung beetles -- that can be a liability to survival? Charles Darwin couldn’t figure it out, but now a Northwestern University research team has a possible explanation for this puzzling phenomenon of evolution.

The researchers developed a mathematical model that made a surprising prediction: In animals with ornamentation, males will evolve out of the tension between natural selection and sexual selection into two distinct subspecies, one with flashy, “costly” ornaments for attracting mates and one with subdued, “low-cost” ornaments.

“Ornamentation does persist in nature, and our quantitative model reveals that a species can split into two subspecies as a result of the ornamentation battle that occurs over time,” said Daniel M. Abrams, an associate professor of engineering sciences and applied mathematics in the McCormick School of Engineering.

A new mathematical model developed by Northwestern University researchers explains why two distinct subspecies evolve in ornamented animals: one with flashy, “costly” ornaments for attracting mates and one with subdued, “low-cost” ornaments. Here, two male taurus scarab beetles, a type of dung beetle, illustrate the subdued subgroup (left) and the showy subgroup (right).
Credit: Douglas Emlen, University of Montana

Evidence from nature agrees. The researchers studied available data on animal ornaments, such as deer antlers, peacock feathers, brightness of certain fish and tail length of some birds, from 15 species. They found the same distribution pattern of ornament sizes across many of the species: The animals often split into the two subgroups predicted by the model, one showy and one subdued, with very few in the middle.

It was deer antlers that first made Abrams, an applied mathematician, wonder why some animals spend precious energy to grow and carry around something that could compromise life. It’s not unusual for male deer and their antlers to get stuck in trees or fences -- or to each other in a fight -- and die.

“Animals with extravagant ornaments are showing just how fit and strong they are -- that they can overcome the costs of these ornaments -- and this attracts the opposite sex,” said Abrams, who led the study.

In fact, the subdued subgroup’s existence is a factor in the ability of individuals in the flashy subgroup to pass on their genes. The contrast gives the more ostentatious individuals physical distinction and cachet, helping to woo mates and propagate themselves.

The study, which aids our understanding of how life has evolved on Earth, will be published Nov. 29 (Nov. 30 in the U.K.) by the biological sciences journal Royal Society Proceedings B.

The study’s other authors are Sara M. Clifton, a graduate student in Abrams’ group, and Rosemary I. Braun, a computational biologist and assistant professor of preventive medicine at Northwestern University Feinberg School of Medicine.

“This is a study of evolution using mathematical biology -- how sexual selection and natural selection play off each other and produce some of the strange things we see in the animal world,” said Clifton, the paper’s first author. “The horned dung beetle from our study is a good example of how large horns really handicap the animal, yet they exist.”

Abrams, Braun and Clifton started with Zahavi’s handicap principle, from 1975, which offers an elegant explanation for the evolution of the flashy ornaments: Ornaments signal individual quality and the ability to overcome high costs. This ensures “honest advertising” to the opposite sex, making mate selection more efficient.

The researchers incorporated both the assumptions of the handicap principle and what evolving ornaments would look like over a long period of time into a mathematical model. The results showed the assumptions are sufficient to explain the previously puzzling observation of the two distinct subgroups of flashy, high-cost ornaments and subdued, low-cost ornaments in a variety of species spanning the animal kingdom.

After developing their model, the researchers studied 23 data sets from 15 different animal species from the published scientific literature and found that all were consistent with their model. There were no exceptions.

“The model is completely independent of the underlying genetic mechanism that causes these ornaments to grow, which I find fascinating,” Braun said. “It tells us that if you have these two competing forces, natural selection and sexual selection, two morphs, or subgroups, will emerge. The model is so general it can be applied to many different species and still have the same explanatory power.”

Where do humans fit in?

“I don’t want to push it too far, but the natural analogy is that individuals also can try to appear more appealing by spending resources on things that cost a lot of money -- expensive homes, cars, clothes or jewelry, for example,” Abrams said.

“The only way you can afford to spend so much money on these things is if you already have a lot of money. It’s demonstrating wealth by throwing away a lot of wealth on these objects, which is similar to deer having showy but costly antlers,” he said.

The James S. McDonnell Foundation (Grant No. 220020230) and the National Science Foundation Graduate Research Fellowship No. DGE-1324585 supported the research.

The title of the Royal Society Proceedings B paper is “Handicap Principle Implies Emergence of Dimorphic Ornaments.”

Contacts and sources: : 
Danny Abrams 
Northwestern University

Tuesday, November 29, 2016

Mongoose Mobs Help Their Friends

In their notorious battles with snakes, dwarf mongooses are more likely to help attack the enemy if they are closely bonded to the individual raising the alarm, reports new experimental research from scientists at the University of Bristol.

Strong bonds, or 'friendships', occur between group members in many species, not just humans. Lead author Dr Julie Kern from the University's School of Biological Sciences, said: "It's well-known that strong bonds can provide long-term health and fitness benefits, but we're only just beginning to understand that there are short-term benefits too."

A short video of a puff adder being mobbed by a group of dwarf mongooses.

Credit: Fiona Carr

For the study, part-funded by a crowd-funding campaign and published in the journal Biology Letters, researchers used grooming and foraging data to establish which mongooses were 'friends'. They then conducted field-based experimental trials to demonstrate that individuals were more likely to respond to the mobbing calls of these groupmates with whom they are more strongly bonded.

Co-author Professor Andy Radford added: "Our results are exciting because they show that strong bonds within social groups may provide key anti-predator benefits. Groupmates may directly improve the survival chances of their 'friends' when they respond to mobbing calls, but may also increase the likelihood of being helped themselves in the future."

One of the dwarf mongooses from the experiment.

Credit; Shannon Benson

The Bristol team studied groups of wild dwarf mongooses in South Africa that have become familiar with their close presence, allowing the researchers to walk within a few metres of them. Dr Kern said: "This habituation gives us a rare opportunity to conduct ecologically relevant experiments in the mongooses' natural habitat and permits the collection of incredibly detailed and accurate information."

Professor Radford concluded: "By looking at responses to mobbing calls, which directly indicate a predator's presence, we can investigate a direct link between friendship and survival; making a mistake during a mobbing event could result in death. It seems that for dwarf mongooses at least, a friend in need is a friend indeed."

Contacts and sources: 
Richard Cottle
University of Bristol

LED Lights Are Much Less Attractive To Nuisance Insects Say Researchers

New research by scientists from the University of Bristol has revealed that domestic LED lights are much less attractive to nuisance insects such as biting midges than traditional filament lamps.

The team now highlights the urgent need for further research on other heat-seeking flies that transmit disease, including mosquitoes that are carriers of pathogens that cause damaging diseases such as malaria and Zika fever.

Midges around a filament light
Credit; University of Bristol

The study, funded by the Natural Environment Research Council and UK lighting manufacturer Integral LED, used customised traps at 18 field test sites across south-west England, illuminated by a series of LED, filament and fluorescent light sources. Over 4,000 insects were carefully identified. The results showed that LEDs attracted four times fewer insects compared with the traditional incandescent lamps, and half as many as were attracted to a compact fluorescent lamp.

Notably, for biting flies (midges in the genus Culicoides, some species of which are vectors of wildlife disease), 80 percent were attracted to the filament lamp, 15 percent to the compact fluorescent and only 2-3 percent to each of the two different LED lamps.

Dr Andy Wakefield led the field research in a project supervised by Professors Gareth Jones and Stephen Harris from the University’s School of Biological Sciences. Dr Wakefield said: "We were surprised by the number of biting flies drawn to the traditional tungsten lights. We do not know why this is but we know that some insects use thermal cues to find warm-blooded hosts in the night, so perhaps they were attracted to the heat given off by the filament bulb."

Co-sponsors of the study, Integral LED were instrumental in the commissioning of the project and provided technical and financial support.

The UK company’s Marketing Director Sanjiv Kotecha said: "As lighting manufacturers, we welcome that a link between LED lights and low attraction to insects has been proven. The energy saving advantages of solid-state lighting are well known, yet the benefits to well-being are only beginning to be revealed."

Contacts and sources:
University of Bristol

Citation: ‘Experimentally comparing the attractiveness of domestic lights to insects: Do LEDs attract fewer insects than conventional light types?’ by A. Wakefield, MEJ Broyles, E Stone, G Jones and S Harris in Ecology and Evolution

Nuclear Powered Diamond Battery Could Last 5000 Years, Solve Nuclear Waste Problem

New technology has been developed that uses nuclear waste to generate electricity in a nuclear-powered battery. A team of physicists and chemists from the University of Bristol have grown a man-made diamond that, when placed in a radioactive field, is able to generate a small electrical current.

The development could solve some of the problems of nuclear waste, clean electricity generation and battery life.

This innovative method for radioactive energy was presented at the Cabot Institute’s sold-out annual lecture - ‘Ideas to change the world’- on Friday, 25 November.

Unlike the majority of electricity-generation technologies, which use energy to move a magnet through a coil of wire to generate a current, the man-made diamond is able to produce a charge simply by being placed in close proximity to a radioactive source.

Tom Scott, Professor in Materials in the University’s Interface Analysis Centre and a member of the Cabot Institute, said: “There are no moving parts involved, no emissions generated and no maintenance required, just direct electricity generation. By encapsulating radioactive material inside diamonds, we turn a long-term problem of nuclear waste into a nuclear-powered battery and a long-term supply of clean energy.”

The team have demonstrated a prototype ‘diamond battery’ using Nickel-63 as the radiation source. However, they are now working to significantly improve efficiency by utilising carbon-14, a radioactive version of carbon, which is generated in graphite blocks used to moderate the reaction in nuclear power plants. Research by academics at Bristol has shown that the radioactive carbon-14 is concentrated at the surface of these blocks, making it possible to process it to remove the majority of the radioactive material. The extracted carbon-14 is then incorporated into a diamond to produce a nuclear-powered battery.

Credit:  The University of Bristol

The UK currently holds almost 95,000 tonnes of graphite blocks and by extracting carbon-14 from them, their radioactivity decreases, reducing the cost and challenge of safely storing this nuclear waste.

Dr Neil Fox from the School of Chemistry explained: “Carbon-14 was chosen as a source material because it emits a short-range radiation, which is quickly absorbed by any solid material. This would make it dangerous to ingest or touch with your naked skin, but safely held within diamond, no short-range radiation can escape. In fact, diamond is the hardest substance known to man, there is literally nothing we could use that could offer more protection.”

Despite their low-power, relative to current battery technologies, the life-time of these diamond batteries could revolutionize the powering of devices over long timescales. The actual amount of carbon-14 in each battery has yet to be decided but one battery, containing 1g of carbon-14, would deliver 15 Joules per day. This is less than an AA battery. Standard alkaline AA batteries are designed for short timeframe discharge: one battery weighing about 20g has an energy storage rating of 700J/g. If operated continuously, this would run out in 24 hours. Using carbon-14 the battery would take 5,730 years to reach 50 per cent power, which is about as long as human civilization has existed.

Professor Scott added: “We envision these batteries to be used in situations where it is not feasible to charge or replace conventional batteries. Obvious applications would be in low-power electrical devices where long life of the energy source is needed, such as pacemakers, satellites, high-altitude drones or even spacecraft.

“There are so many possible uses that we’re asking the public to come up with suggestions of how they would utilise this technology by using #diamondbattery.”

Contacts and sources:
The University of Bristol 

Learning Makes Animals Intelligent

The fact that animals can use tools, have self-control and certain expectations of life can be explained with the help of a new learning model for animal behaviour. Researchers at Stockholm University and Brooklyn College have combined knowledge from the fields of artificial intelligence, ethology and the psychology of learning to solve several problems concerning the behaviour and intelligence of animals.

Animals are often very effective; an oystercatcher opens mussels quickly, a baboon takes every opportunity to steal food from tourists or a rat navigates with ease between the bins in a park. Previously these behaviours have been considered to be inherited instincts, even though it is well known that animals have great learning abilities.

An orangutan builds an umbrella against the rain. Efficient and intelligent behavior that can be explained by new research from Stockholm University and Brooklyn College.
Credit: Johan Lind/N.

Researchers from Stockholm University and Brooklyn College have now created an associative learning model that explains how effective behaviours can arise. This means that an animal does not only learn that the last step of a behaviour chain, the one that is rewarding, is valuable. An animal can learn that all steps towards the reward are valuable.

"Our learning model may also explain how advanced behaviours are created at an individual level. Behaviours like self-control, chimpanzee tool use as well as other phenomena like animals having certain expectations of live", says Magnus Enquist, professor of ethology at Stockholm University. "Similar models are used in the field of artificial intelligence, but they have been ignored in animal studies."

A pigeon takes the subway instead of flying. Efficient and intelligent behavior can be explained by new research from Stockholm University and Brooklyn College.

Photo: Johan Lind/N.

Since the 1970s it has been known that animals weigh the cost of a certain behaviour against the profit and that they, to a high degree, make optimal decisions, which is assumed to be genetically determined. The research group's new model deals not only with learning, it also takes into account the idea that what animals are able to learn can be genetically regulated.

"Young animals are often a bit clumsy, while adult animals are extremely skilled. A small cub does not even consider a vole as food, while an adult fox is an expert vole catcher", says Johan Lind associate professor of ethology at Stockholm University. "Our model shows how genetic regulation of learning can influence the development of species-specific behaviour and intelligence since evolution can affect curiosity and the speed of learning among other things."

The researchers' new model could also explain counterproductive behaviour in artificial environments.

"Many learning models can explain optimal behaviour, but to explain counterproductive behaviour an understanding of the mechanisms of the behaviour is needed. Using our model, we manage to explain why animals get stuck in suboptimal behaviour. Like a hamster running in its hamster wheel despite having food next to it. Our model has captured fundamental aspects of learning", says Stefano Ghirlanda, professor of psychology at Brooklyn College in New York.

The learning model and the research results were recently published in the journal Royal Society Open Science ("The power of associative learning and the ontogeny of optimal behavior"). [link]

Contacts and sources:
Magnus Enquist, professor of ethology at Stockholm University

Timing The Shadow Of A Potentially Habitable Extrasolar Planet Paves The Way To Search For Alien Life

A group of researchers from the National Astronomical Observatory of Japan (NAOJ), the University of Tokyo, and the Astrobiology Center among others has observed the transit of a potentially Earth-like extrasolar planet known as K2-3d using the MuSCAT instrument on the Okayama Astrophysical Observatory 188-cm telescope.

A transit is a phenomenon in which a planet passes in front of its parent star, blocking a small amount of light from the star, like a shadow of the planet. While transits have previously been observed for thousands of other extrasolar planets, K2-3d is important because there is a possibility that it might harbor extraterrestrial life.

By observing its transit precisely using the next generation of telescopes, such as TMT, scientists expect to be able to search the atmosphere of the planet for molecules related to life, such as oxygen.

This collage summarizes the research. Using the Okayama 188-cm Reflector Telescope and the observational instrument MuSCAT (See real photo on the bottom left.), researchers succeeded in observing the extrasolar planet K2-3d, which is about the same size and temperature as the Earth, pass in front of its host star blocking some of the light coming from the star (See artistic visualization at the top.), making it appear to dim (See real data on the bottom right.).
Credit: NAOJ

With only the previous space telescope observations, however, researchers can't calculate the orbital period of the planet precisely, which makes predicting the exact times of future transits more difficult. This research group has succeeded in measuring the orbital period of the planet with a high precision of about 18 seconds. This greatly improved the forecast accuracy for future transit times. So now researchers will know exactly when to watch for the transits using the next generation of telescopes. This research result is an important step towards the search for extraterrestrial life in the future.


K2-3d is an extrasolar planet about 150 light-years away that was discovered by the NASA K2 mission (the Kepler telescope's "second light") (Note 1). K2-3d's size is 1.5 times the size of the Earth. The planet orbits its host star, which is half the size of the Sun, with a period of about 45 days. Compared to the Earth, the planet orbits close to its host star (about 1/5 of the Earth-Sun distance). But, because the temperature of the host star is lower than that of the Sun, calculations show that this is the right distance for the planet to have a relatively warm climate like the Earth's. There is a possibility that liquid water could exist on the surface of the planet, raising the tantalizing possibility of extraterrestrial life.

K2-3d's orbit is aligned so that as seen from Earth, it transits (passes in front of) its host star. This causes, short, periodic decreases in the star's brightness, as the planet blocks some of the star's light. This alignment enables researchers to probe the atmospheric composition of these planets by precise measurement of the amount of blocked starlight at different wavelengths.

About 30 potentially habitable planets that also have transiting orbits were discovered by the NASA Kepler mission, but most of these planets orbit fainter, more distant stars. Because it is closer to Earth and its host star is brighter, K2-3d is a more interesting candidate for detailed follow-up studies (See Figure 2). The brightness decrease of the host star caused by the transit of K2-3d is small, only 0.07%. However, it is expected that the next generation of large telescopes (Note 2) will be able to measure how this brightness decrease varies with wavelength, enabling investigations of the composition of the planet's atmosphere. If extraterrestrial life exists on K2-3d, scientists hope to be able to detect molecules related to it, such as oxygen, in the atmosphere.

Transiting planets located in the habitable zone (the orbital region where a planet could hold liquid water on the surface), plotted in terms of planet radius vs. host star magnitude (brightness). Black circles represent confirmed planets discovered by the Kepler mission and white circles represent unconfirmed planet candidates. The orange triangles represent the Earth sized planets TRAPPIST-1c and TRAPPIST-1d observed 40 light-years away by a ground based telescope. TRAPPIST-1c and TRAPPIST-1d are thought to be just outside the habitable zone, but they are plotted for reference. The host star of K2-3d (red star) is the brightest in this figure.(credit: NAOJ)

Credit: NAOJ

[MuSCAT Observations and Transit Ephemeris Improvements]

The orbital period of K2-3d is about 45 days. Since the K2 mission's survey period is only 80 days for each area of sky, researchers could only measure two transits in the K2 data. This isn't sufficient to measure the planet's orbital period precisely, so when researchers attempt to predict the times of future transits, creating something called a "transit ephemeris," there are uncertainties in the predicted times. 

These uncertainties grow larger as they try to predict farther into the future. Therefore, early additional transit observations and adjustments to the ephemeris were required before researchers lost track of the transit. Because of the importance of K2-3d, the Spitzer Space Telescope observed two transits soon after the planet's discovery, bringing the total to four transit measurements. However, the addition of even a single transit measurement farther in the future can help to yield a significantly improved ephemeris.

Using the Okayama 188-cm Reflector Telescope and the latest observational instrument MuSCAT, the team observed a transit of K2-3d for the first time with a ground based telescope. Though a 0.07% brightness decrease is near the limit of what can be observed with ground based telescopes, MuSCAT's ability to observe three wavelength bands simultaneously enhanced its ability to detect the transit. By reanalyzing the data from K2 and Spitzer in combination with this new observation, researchers have greatly improved the precision of the ephemeris, determining the orbital period of the planet to within about 18 seconds (1/30 of the original uncertainty). This improved transit ephemeris (Figure 3) ensures that when the next generation of large telescopes come online, they will know exactly when to watch for transits. Thus these research results help pave the way for future extraterrestrial life surveys.

Fiture 3.  Predicted transit time deviation from the improved K2-3d transit ephemeris based on this research. The solid red line indicates the predicted times based on this research, the shaded area shows the uncertainty range. 

Squares, triangles, and circles are respectively the transit time data from the Kepler Telescope, Spitzer Space Telescope, and the latest observing instrument MuSCAT on the Okayama 188-cm Reflector Telescope. Gray marks show the values calculated in previous research and black marks represent the values re-calculated in this research.  Purple and orange dotted lines are the transit ephemerides calculated in previous research using the K2 and the K2+Spitzer data, respectively. This research succeeded in correcting the predictions for the 2018 transit times by more than an hour. 

Credit: NAOJ

Future Work

The NASA K2 mission will continue until at least February 2018, and is expected to discover more potentially habitable planets like K2-3d. Furthermore, K2's successor, the Transiting Exoplanet Survey Satellite (TESS), will be launched in December 2017. TESS will survey the whole sky for two years, and is expected to detect hundreds of small planets like K2-3d near our Solar System. To characterize a 'Second Earth' using the next generation of large telescopes, it will be important to measure the ephemerides and characteristics of planets with additional transit observations using medium sized ground-based telescopes. The team will continue using MuSCAT for research related to the future search for extraterrestrial life.

Contacts and sources:
Dr. Akihiko Fukui
National Institutes Of Natural Sciences

National Astronomical Observatory of Japan

1. The discovery of K2-3d was reported by a research team led by Ian Crossfield (University of California, Santa Cruz) in 2015.

2. The next generation of large telescopes includes the James Webb Space Telescope (JWST), which NASA will launch in 2018, and the Thirty Meter Telescope (TMT), which is being pursued through international collaboration including Japan.

Citation: Ground-BasedTransit Observation Of The Habitable-Zone Super-Earth K2-3D The Astronomical Journal, Volume 152, Number 6

New Study Shows Marijuana Users Have Low Blood Flow to the Brain

Hippocampus, the brain's key memory and learning center, has the lowest blood flow in marijuana users suggesting higher vulnerability to Alzheimer's.

As the U.S. races to legalize marijuana for medicinal and recreational use, a new, large scale brain imaging study gives reason for caution. Published in the Journal of Alzheimer's Disease, researchers using single photon emission computed tomography (SPECT), a sophisticated imaging study that evaluates blood flow and activity patterns, demonstrated abnormally low blood flow in virtually every area of the brain studies in nearly 1,000 marijuana users compared to healthy controls, including areas known to be affected by Alzheimer's pathology such as the hippocampus.

This shows a sample case of a visual 3-D rendering of a baseline SPECT scan of a longstanding marijuana user compared to a control subject. The marijuana user has multiple perfusion defects with lower perfusion shown as scalloping and gaps in perfusion of the temporal and parietal areas.

Credit:  Journal of Alzheimer's Disease

All datawere obtained for analysis from a large multisite database, involving 26,268 patients who came for evaluation of complex, treatment resistant issues to one of nine outpatient neuropsychiatric clinics across the United States (Newport Beach, Costa Mesa, Fairfield, and Brisbane, CA, Tacoma and Bellevue, WA, Reston, VA, Atlanta, GA and New York, NY) between 1995-2015. Of these, 982 current or former marijuana users had brain SPECT at rest and during a mental concentration task compared to almost 100 healhty controls. 

Predictive analytics with discriminant analysis was done to determine if brain SPECT regions can distinguish marijuana user brains from controls brain. Low blood flow in the hippocampus in marijuana users reliably distinguished marijuana users from controls. The right hippocampus during a concentration task was the single most predictive region in distinguishing marijuana users from their normal counterparts. Marijuana use is thought to interfere with memory formation by inhibiting activity in this part of the brain.

According to one of the co-authors on the study Elisabeth Jorandby, M.D., "As a physician who routinely sees marijuana users, what struck me was not only the global reduction in blood flow in the marijuana users brains , but that the hippocampus was the most affected region due to its role in memory and Alzheimer's disease. Our research has proven that marijuana users have lower cerebral blood flow than non-users. Second, the most predictive region separating these two groups is low blood flow in the hippocampus on concentration brain SPECT imaging. This work suggests that marijuana use has damaging influences in the brain - particularly regions important in memory and learning and known to be affected by Alzheimer's."

Dr. George Perry, Editor in Chief of the Journal of Alzheimer's Disease said, "Open use of marijuana, through legalization, will reveal the wide range of marijuana's benefits and threats to human health. This study indicates troubling effects on the hippocampus that may be the harbingers of brain damage."

According to Daniel Amen, M.D., Founder of Amen Clinics, "Our research demonstrates that marijuana can have significant negative effects on brain function. The media has given the general impression that marijuana is a safe recreational drug, this research directly challenges that notion. In another new study just released, researchers showed that marijuana use tripled the risk of psychosis. Caution is clearly in order."

Contacts and sources:
Natalie Buchoz
IOS Press

Platypus Venom Could Hold Key to Diabetes Treatment

Australian researchers have discovered remarkable evolutionary changes to insulin regulation in two of the nation's most iconic native animal species - the platypus and the echidna - which could pave the way for new treatments for type 2 diabetes in humans.

The findings, now published in the Nature journal Scientific Reports, reveal that the same hormone produced in the gut of the platypus to regulate blood glucose is also surprisingly produced in their venom.

The research is led by Professor Frank Grutzner at the University of Adelaide and Associate Professor Briony Forbes at Flinders University.

The hormone, known as glucagon-like peptide-1 (GLP-1), is normally secreted in the gut of both humans and animals, stimulating the release of insulin to lower blood glucose.

A platypus. The same hormone produced in the gut of the platypus to regulate blood glucose is also produced in their venom, researchers have found -- and that hormone could be used in possible type 2 diabetes treatments.
Credit:  NIH

But GLP-1 typically degrades within minutes.

In people with type 2 diabetes, the short stimulus triggered by GLP-1 isn't sufficient to maintain a proper blood sugar balance. As a result, medication that includes a longer lasting form of the hormone is needed to help provide an extended release of insulin.

"Our research team has discovered that monotremes - our iconic platypus and echidna - have evolved changes in the hormone GLP-1 that make it resistant to the rapid degradation normally seen in humans," says co-lead author Professor Frank Grutzner, from the University of Adelaide's School of Biological Sciences and the Robinson Research Institute.

"We've found that GLP-1 is degraded in monotremes by a completely different mechanism. Further analysis of the genetics of monotremes reveals that there seems to be a kind of molecular warfare going on between the function of GLP-1, which is produced in the gut but surprisingly also in their venom," he says.

The platypus produces a powerful venom during breeding season, which is used in competition among males for females.

"We've discovered conflicting functions of GLP-1 in the platypus: in the gut as a regulator of blood glucose, and in venom to fend off other platypus males during breeding season. This tug of war between the different functions has resulted in dramatic changes in the GLP-1 system," says co-lead author Associate Professor Briony Forbes, from Flinders University's School of Medicine.

"The function in venom has most likely triggered the evolution of a stable form of GLP-1 in monotremes. Excitingly, stable GLP-1 molecules are highly desirable as potential type 2 diabetes treatments," she says.

Professor Grutzner says: "This is an amazing example of how millions of years of evolution can shape molecules and optimise their function.

"These findings have the potential to inform diabetes treatment, one of our greatest health challenges, although exactly how we can convert this finding into a treatment will need to be the subject of future research."

GLP-1 has also been discovered in the venom of echidnas. But while the platypus has spurs on its hind limbs for delivering a large amount of venom to its opponent, there is no such spur on echidnas.

"The lack of a spur on echidnas remains an evolutionary mystery, but the fact that both platypus and echidnas have evolved the same long-lasting form of the hormone GLP-1 is in itself a very exciting finding," Professor Grutzner says.

Contacts and sources:
Professor Frank Grutzner
School of Biological Sciences and Robinson Research Institute
The University of Adelaide

Associate Professor Briony Forbes
School of Medicine
Flinders University

Low-Mass Supernova Triggered Formation Of Solar System: Supernova Left Forensic Evidence In Meteorites

A research team led by University of Minnesota School of Physics and Astronomy Professor Yong-Zhong Qian uses new models and evidence from meteorites to show that a low-mass supernova triggered the formation of our solar system.

The findings are published in the most recent issue of Nature Communications, a leading scientific journal.

About 4.6 billion years ago, a cloud of gas and dust that eventually formed our solar system was disturbed. The ensuing gravitational collapse formed the proto-Sun with a surrounding disc where the planets were born. A supernova—a star exploding at the end of its life-cycle—would have enough energy to compress such a gas cloud. Yet there was no conclusive evidence to support this theory. In addition, the nature of the triggering supernova remained elusive. 

That cloud might be similar to some region in this much larger complex of gas and dust about 4,500 light-years away in the constellation Cygnus observed by NASA's Spitzer Telescope. 
Image credit: NASA/JPL-Caltech/Harvard-Smithsonian CfA 

Qian and his collaborators decided to focus on short-lived nuclei present in the early solar system. Due to their short lifetimes, these nuclei could only have come from the triggering supernova. Their abundances in the early solar system have been inferred from their decay products in meteorites. As the debris from the formation of the solar system, meteorites are comparable to the leftover bricks and mortar in a construction site. They tell us what the solar system is made of and in particular, what short-lived nuclei the triggering supernova provided.

“This is the forensic evidence we need to help us explain how the solar system was formed,” Qian said. “It points to a low-mass supernova as the trigger.”

Qian is an expert on the formation of nuclei in supernovae. His previous research has focused on the various mechanisms by which this occurs in supernovae of different masses. His team includes the lead author of the paper, Projjwal Banerjee, who is a former Ph.D. student and postdoctoral research associate, and longtime collaborators Alexander Heger of Monash University, Australia, and Wick Haxton of the University of California, Berkeley. Qian and Banerjee realized that previous efforts in studying the formation of the solar system were focused on a high-mass supernova trigger, which would have left behind a set of nuclear fingerprints that are not present in the meteoric record.

Qian and his collaborators decided to test whether a low-mass supernova, about 12 times heavier than our sun, could explain the meteoritic record. They began their research by examining Beryllium-10, a short-lived nucleus that has 4 protons (hence the fourth element in the periodic table) and 6 neutrons, weighing 10 mass units. This nucleus is widely distributed in meteorites.

In fact the ubiquity of Beryllium-10 was something of a mystery in and of itself. Many researchers had theorized that spallation—a process where high-energy particles strip away protons or neutrons from a nucleus to form new nuclei—by cosmic rays was responsible for the Beryllium-10 found in meteorites. Qian said that this hypothesis involves many uncertain inputs and presumes that Beryllium-10 cannot be made in supernovae.

Using new models of supernovae, Qian and his collaborators have shown that Beryllium-10 can be produced by neutrino spallation in supernovae of both low and high masses. However, only a low-mass supernova triggering the formation of the solar system is consistent with the overall meteoritic record.

“The findings in this paper have opened up a whole new direction in our research,” Qian said. “In addition to explaining the abundance of Beryllium-10, this low-mass supernova model would also explain the short-lived nuclei Calcium-41, Palladium-107, and a few others found in meteorites. What it cannot explain must then be attributed to other sources that require detailed study.”

Qian said the group would like to examine the remaining mysteries surrounding short-lived nuclei found in meteorites. The first step, however is to further corroborate their theory by looking at Lithium-7 and Boron-11 that are produced along with Beryllium-10 by neutrino spallation in supernovae. Qian said they may examine this in a future paper and urged researchers studying meteorites look at the correlations among these three nuclei with precise measurements.

The research is funded by the Department of Energy Office of Nuclear Physics. Qian, Banerjee, and Heger are also scientific participants of the Joint Institute for Nuclear Astrophysics-Center for the Evolution of the Elements, a National Science Foundation Physics Frontier Center.

Contacts and sources:
Rhonda Zurn 
University of Minnesota

Citation: “Evidence from stable isotopes and Be-10 for solar system formation triggered by a low-mass supernova,” Nature Communications website.

A First Antarctic Ground Beetle Found

Ball's Antarctic Tundra Beetle is also the second known beetle for the southernmost continent with living descendants.

Fossilised forewings from two individuals, discovered on the Beardmore Glacier, revealed the first ground beetle known from the southernmost continent. It is also the second beetle for the Antarctic insect fauna with living descendants. 

The new species, which for now is also the sole representative of a new genus, is to be commonly known as Ball's Antarctic Tundra Beetle. Scientists Dr Allan Ashworth, North Dakota State University, and Dr Terry Erwin, Smithsonian Institution, published their findings in the open access journal ZooKeys.

The fossilized forewings of the new ground beetle A. balli.

Credit: Dr. Allan Ashworth

The insect fauna in Antarctica is so poor that today it consists of only three species of flightless midges, with one of them having been probably introduced from the subantarctic island of South Georgia. The absence of biodiversity is considered to be a result of lack of moisture, vegetation and low temperatures.

Following their study, the authors conclude that the beetle must have inhabited the sparsely-vegetated sand and gravel banks of a meltwater-fed stream that was once part of an outwash plain at the head of a fjord in the Transantarctic Mountains. Plants associated with the extinct beetle include southern beech, buttercup, moss mats, and cushion plants, all typical for a tundra ecosystem. The species may or may not have been able to fly.

The type locality for A. balli sp. n. is a siltstone lens within a sequence of lodgement tills exposed in the gulley wall to the left of the person highest in the gully.
Credit: Dr. Allan Ashworth

The closest modern relatives to the extinct species live in South America, the Falkland Islands, South Georgia, Tasmania and Australia. Tracking the ancient lineage of this group of beetles, known as the carabid beetle tribe Trechini, confirms that they were once widely distributed in Gondwana, the supercontinent that used to unite what today we recognise as Antarctica, South America, Africa, Madagascar, Australia, the Arabian Peninsula and the Indian Subcontinent. Ball's Antarctic Tundra Beetle is also an evidence that even after Gondwana broke apart, the tundra ecosystem persevered in Antarctica for millions of years.

"The conflicting signals both in anatomical attributes and biogeography, and in ecological setting as well, leave open the question of relationships, thus giving us no alternative but to flag the species represented by fossil evidence through erection of new genus status, hence drawing attention to it and the need for further paleontological studies in Antarctica," speak of their discovery the authors.

The type locality for Antarctotrechus balli sp. n. is shown by the red star. Image map is a modified MODIS Mosaic of Antarctica from National Snow and Ice Data Center, http://nsidc.org/data/moa/

Credit: Dr. Allan Ashworth

The new Ball's Antarctic Tundra Beetle is scientifically identified as Antarctotrechus balli, where the genus name (Antarctotrechus) refers to its being related to the tribe Trechini, and the species name (balli) honours distinct expert of ground beetles Dr. George E. Ball, who celebrated his 90th birthday on 26th September, 2016.


Contacts and sources:
Dr. Allan Ashworth
Pensoft Publishers

Citation: Ashworth AC, Erwin TL (2016) Antarctotrechus balli sp. n. (Carabidae, Trechini): the first ground beetle from Antarctica. ZooKeys 635: 109-122. https://doi.org/10.3897/zookeys.635.10535

What Will They Make? Molecular Assembly Produces Complex DNA Nanostructures, Next Molecular Robots

Many self-organized systems in nature exploit a sophisticated blend of deterministic and random processes. No two trees are exactly alike because growth is random, but a Redwood can be readily distinguished from a Jacaranda as the two species follow different genetic programs. The value of randomness in biological organisms is not fully understood, but it has been hypothesized that it allows for smaller genome sizes—because not every detail must be encoded. Randomness also provides the variation underlying adaptive evolution.

In contrast to biology, engineering seldom takes advantage of the power of randomness for fabricating complex structures. Now, a group of Caltech scientists has demonstrated that randomness in molecular self-assembly can be combined with deterministic rules to produce complex nanostructures out of DNA.

Colored atomic force microscope image of self-assembled random tree structures on the surface of DNA tile arrays. Each tree has a single loop as the “root”.

Credit: Caltech / Grigory Tikhomirov, Philip Petersen and Lulu Qian

The work, done in the laboratory of Assistant Professor of Bioengineering Lulu Qian, appears in the November 28 issue of the journal Nature Nanotechnology.

Living things use DNA to store genetic information, but DNA can also be used as a robust chemical building block for molecular engineering. The four complementary molecules that make up DNA, called nucleotides, bind together only in specific ways: A's bind with T's, and G's bind with C's. In 2006, Paul Rothemund (BS '94), research professor of bioengineering, computing and mathematical sciences, and computation and neural systems at Caltech, invented a technique called DNA origami that takes advantage of the matching between long strands of DNA nucleotides, folding them into everything from nanoscale artwork to drug-delivery devices. The self-assembled structures formed through DNA origami may be functional by themselves or they may be used as templates to organize other functional molecules—such as carbon nanotubes, proteins, metal nanoparticles, and organic dyes—with unprecedented programmability and spatial precision.

Using DNA origami as a building block, researchers have made larger DNA nanostructures, such as periodic arrays of origami tiles. However, because the building block is just repeated everywhere, the complexity of patterns that can be formed on these larger structures is quite limited. Entirely deterministic assembly processes—controlling the design of each individual tile and its distinct position in the array—can give rise to complex patterns, but these processes do not scale up well.

 Conversely, if only random processes are involved and the global features of the array are not controlled by design rules, it is impossible to create complex patterns with desired properties without simultaneously generating a large fraction of undesired molecules that are wasted. Until the work by Qian and her colleagues, combining deterministic processes with random ones had never been systematically explored to create complex DNA nanostructures.

"We were looking for molecular self-assembly principles that embrace both deterministic and random aspects," says Qian. "We developed a simple set of rules that allow DNA tiles to bind randomly but only into specific controlled patterns."

The approach involves designing patterns on individual tiles, modulating the ratios of different tiles, and determining which tiles can bind together during self-assembly. This leads to large-scale emergent features with tunable statistical properties—a phenomenon the authors dub "programmable disorder."

"The structures that we can build have programmably random aspects," says Grigory Tikhomirov, a senior postdoctoral scholar in biology and biological engineering, and lead author on the paper. "For example, we can make structures that have lines that take seemingly random paths, but we can ensure that they never intersect and always eventually close up into loops."

In addition to loops, the team chose two other examples, mazes and trees, to demonstrate that many nontrivial properties of these structures can be controlled by simple local rules. They found these examples interesting because loop, maze, and tree structures widely exist in nature across multiple scales. For example, lungs are tree structures at the millimeter to centimeter scale, and neural dendrites are tree structures at the micrometer to millimeter scale. The controlled properties that they showed include the branching rules, the growth directions, the proximity between adjacent networks, and the size distribution.

The group was first inspired by the classic Truchet tiles, which are square tiles with two diagonally symmetrical arcs of DNA on the surface. There are two rotationally asymmetrical orientations of the arc pattern (see image below). Allowing a random choice of the two tile orientations at each location in the array, the pattern will continue through neighboring tiles, either becoming loops of various sizes or exiting from an edge of the array.

Left, Truchet tiles have two arcs that are rotationally asymmetrical. Right, popular board games inspired by Truchet tiles. 

 Courtesy of L. Qian

To create Truchet arrays at the molecular scale, the team used the DNA origami technique to fold DNA into square tiles and then designed the interactions between these tiles to encourage them to self-assemble into large two-dimensional arrays.

"Because all molecules bump into each other while floating around in a test tube during the process of self-assembly, the interactions should be weak enough to allow the tiles to rearrange themselves and avoid being trapped at any undesired configurations," says Philip Petersen, a graduate student in the Qian laboratory and co-first author on the paper. "On the other hand, the interactions should be specific enough so the desired interactions are always much preferred over undesired, spurious interactions."

Different types of global patterns emerge when tiles are marked with different local patterns. For example, if each randomly oriented tile carries a "T" rather than two arcs, the global pattern is a maze with branches and loops rather than only loops (see images below). If the self-assembly rules constrain the possible relative orientation of neighboring "T" tiles, it is possible to ensure that other than a single "root," the branches in the mazes never close into loops—producing trees. To explore the full generality of these principles, Qian's team developed a programming language for random DNA origami tilings.

 Self-assembled loop, maze, and tree structures on the surface of DNA tile arrays. Top row, random mazes with three-way and four-way junctions of varying distances between adjacent junctions versus only three-way junctions of a fixed distance between adjacent junctions. Middle row, random trees (each tree has a single loop as the "root") with longer branches of varying lengths versus shorter branches of fixed lengths. Bottom row, random loops with tunable lengths and number of crossings. 

Courtesy of L. Qian

"With this programming language, the design process starts with a high-level description of the tiles and arrays, which can be automatically translated to abstract array diagrams and numerical simulations, then moves to DNA origami tile design including how the tiles interact with each other on their edges. Finally, we design DNA sequences," Qian says. "With these DNA sequences, it is straightforward for researchers to order the DNA strands, mix them in a test tube, wait for the molecules to self-assemble into the designed structures overnight, and obtain images of the structures using an atomic force microscope."

The group's method of programmable disorder has diverse future applications. For example, it could be used to build complex testing environments for ever-more-sophisticated molecular robots—DNA-based nanoscale machines that can move on a surface, pick up or drop off proteins or other kinds of molecules as cargos, and make decisions about navigation and actions.

"The potential applications are much broader," Qian adds. Since the 1990s, random one-dimensional chains of polymers have been used to revolutionize chemical and material synthesis, drug delivery, and nucleic acid chemistry by creating vast combinatorial libraries of candidate molecules and then selecting or evolving the best ones in the laboratory. "Our work extends the same principle to two-dimensional networks of molecules and now creates new opportunities for fabricating more complex molecular devices organized by DNA nanostructures," she says.

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Written by Lori Dajose

The paper is titled "Programmable disorder in random DNA tilings." This work was funded by the National Science Foundation, a National Institutes of Health National Research Service Award, and the Burroughs Wellcome Fund.