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Wednesday, 20 November 2019

More than 140 new Nazca geoglyphs have been discovered


In 1927, archaeologists discovered for the first time from the air stylized representations of humans, animals and objects of various sizes (between a few tens of meters and several kilometers) drawn in the soil of the Nazca desert in southern Peru. Called the Nazca Geoglyphs, the purpose in which they were traced by the Nazca civilization is still unknown. Recently, a team of archaeologists discovered 143 new geoglyphs, including one thanks to artificial intelligence . This discovery could help to better understand the functions of these representations.

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Scientists have discovered more than 140 new geoglyphs, known as Nazca Geoglyphs (or Nazca Lines): an ancient and mysterious group of giant characters engraved in the desert of southern Peru. These massive and sprawling representations of human beings, animals and objects can be as old as 2500 years old and so impressive that many of them can only be identified from the air.

Archaeologists at the Japanese University of Yamagata report that a long-term study conducted since 2004 has uncovered 143 previously unknown Nazca geoglyphs, including a figure who escaped human detection and discovered by artificial intelligence.

Humanoid geoglyph (about 10 meters long). Credits: Yamagata University

Geoglyphs with still unexplained objectives

The newly identified geoglyphs would have been created between at least 100 BCE and 300 EC. Although the purpose of these great motifs inspired by the ancient culture of Nazca remains controversial, the way they were made is known to archaeologists. " All these figures were created by removing the black stones that cover the earth, exposing the white sand underneath, " says the research team.

Geoglyph representing a bird (about 100 meters long). Credits: Yamagata University

Previous assumptions have suggested that the Nazca people have shaped the giant geoglyphs - some of which are hundreds of meters long - to be seen by deities in the sky or to serve astronomical purposes.

In the new research, led by anthropologist and archaeologist Masato Sakai, the team analyzed the high-resolution satellite imagery of the Nazca region, also conducted fieldwork and identified two main types of geoglyphs.

Two types of geoglyphs with potentially distinct functions

The oldest geoglyphs (100 AECs), called type B, are generally less than 50 meters, while the slightly more recent ones (100 and 300 EC), called type A, extend over 50 meters, with the largest geoglyph discovered by the team measuring more than 100 meters.

Researchers believe that type A geoglyphs, larger, often shaped like animals, were ritual places where people organized ceremonies involving the destruction of various pottery vases.

Geoglyph representing a two-headed serpent (about 30 meters long). Credits: Yamagata University

On the other hand, the smaller Type B patterns were located along trails and could have served as a relay to guide travelers - possibly to a larger Type A ritual space where people would gather. Some of these Type B designs are really tiny, the smallest of new discoveries measuring less than 5 meters, making it difficult to find this type of line.

The help of artificial intelligence in the discovery of geoglyphs

To this end, as part of a recent experimental collaboration that began in 2018 with IBM researchers, the team used a company-developed Deep Learning artificial intelligence that runs on a geospatial analysis system. called IBM PAIRS geoscope.

Humanoid geoglyph discovered by IBM's artificial intelligence (about 4 meters long). Credits: Yamagata University

The Learning Network - IBM Watson Machine Learning Accelerator (WMLA) - has screened huge volumes of images of drones and satellites to see if it can spot hidden marks related to the Nazca lines.

The system found a match: the faded outline of a small humanoid type B, resting on two feet. Although the symbolic meaning of this strange and ancient character is not yet clear, the researchers point out that the geoglyph was located near a path, which makes it perhaps one of the supposed beacons.

Source

Tuesday, 19 November 2019

NASA confirms the presence of water vapor on the surface of Europa


The fourth largest natural satellite of Jupiter and sixth largest in the Solar System, Europa has been of interest to planetologists for many years. About forty years ago, the Voyager program provided the first detailed picture of the veined surface of the icy moon. In the last decades, the data collected on Europa has made it a priority target for space agencies in the search for life. And recently, planetologists have confirmed the presence of water vapor in Europe.

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What makes this moon so attractive is the possibility that it has all the ingredients necessary for life. Planetologists have evidence that one of these ingredients, liquid water, is present under the icy surface and can sometimes burst into space in the form of gigantic geysers. But so far no one has been able to confirm the presence of water in these plumes by directly detecting the water molecule.

Europa: water vapor and a potential ocean of liquid water

Now, an international research team led by NASA's Goddard Space Flight Center has directly detected water vapor for the first time over the surface of Europa. The team did this detection by surveying Europa through one of the largest telescopes in the world in Hawaii.

By confirming the presence of water vapor over Europa, planetologists can better understand the inner workings of the moon. For example, it helps to support the idea that there is an ocean of liquid water, perhaps twice as large as the Earth's, beneath the thick ice shell of that moon. Some astrophysicists suspect that another source of water for the plumes could be shallow reservoirs of melted water ice.

Although planetologists have still not surveyed the interior of Europe, the predominant hypothesis suggests the existence of an ocean of liquid water beneath its frozen surface. Credits: NASA

" The essential chemical elements (carbon, hydrogen, oxygen, nitrogen, phosphorus and sulfur) and energy sources, two of the three requirements of life, are present throughout the Solar System. But the third - liquid water - is a little hard to find beyond the Earth, "said Lucas Paganini, NASA's planetologist. " Although the scientists have not yet detected the liquid water directly, we have found the second best thing: water in the form of steam ."

First direct detection of water molecules over Europa

In Nature Astronomy , Paganini and his team said they detected enough water ejected from Europa (at a rate of 2360 kilograms per second) to fill an Olympic pool in minutes. However, the authors also discovered that water appears too rarely, at least in sufficient quantity, to be detected from Earth.

" For me, the interest of this work is not only the first direct detection of water over Europa, but also its absence within the limits of our detection method, " says Paganini.

Indeed, Paganini's team detected the weak but distinct signal of water vapor during 17 nights of observation between 2016 and 2017. Looking at the moon from WM Keck observatory at the top of Mauna Kea volcano in Hawaii, researchers have seen water molecules on the main hemisphere of Europa. (Europa, like the Earth's moon, is gravitationally locked on its host planet, so the main hemisphere is always oriented in the direction of the orbit, while the secondary hemisphere is always in the opposite direction).

Differentiate terrestrial water vapor from that of Europa: models in reinforcement

For this, the researchers used a Keck observatory spectrometer, which measures the chemical composition of planetary atmospheres by means of the infrared light they emit or absorb. Molecules such as water emit specific frequencies of infrared light when they interact with solar radiation.

When interacting with solar radiation, water molecules emit specific infrared frequencies. Credits: Michael Lentz / NASA Goddard

Detecting water vapor on other worlds is a challenge. Existing spacecraft have limited capabilities to detect it, and scientists using ground-based telescopes must take into account the distortion effects of the Earth's atmosphere.

To minimize this effect, Paganini's team used complex mathematical and computer modeling to simulate the conditions of the Earth's atmosphere, in order to differentiate between atmospheric water from Earth and Europa from the atmosphere. data returned by the Keck spectrograph.

We conducted rigorous safety checks to eliminate potential contaminants in ground observations, " said Avi Mandell, a planetologist on the Paganini team. " But in the end, we will have to get closer to Europa to see what is really happening ."

Structure of Europa: study it in detail thanks to the Europa Clipper mission

Scientists will soon be able to get close enough to Europa to resolve their outstanding questions about the internal and external functioning of this possibly habitable world. The next mission, Europa Clipper, which is scheduled for launch in the mid-2020s, will complete half a century of scientific discoveries that began with a modest photo.

When it arrives in Europa, the Clipper orbiter will carry out a detailed study of the surface, the deep interior, the weak atmosphere, the submarine ocean and possibly even smaller active vents. Clipper will try to take images of all the plumes and sample the molecules he will find in the atmosphere to study with his mass spectrometers. He will also look for a site from which a future lander could collect a sample.

In this video, NASA returns in detail on the detection of water vapor in Europa:



Bibliography:

Article: A measurement of water vapour amid a largely quiescent environment on Europa

authors: L. Paganini, G. L. Villanueva, L. Roth, A. M. Mandell, T. A. Hurford, K. D. Retherford & M. J. Mumma

Nature Astronomy

Source

New material breaks all records for thermoelectric power generation


More and more technologies are using thermoelectricity to supply energy. Thermoelectric energy comes from the conversion of heat into electricity through temperature differences. However, the usual thermoelectric materials generate a relatively small amount of energy. But recently, Austrian physicists have developed a brand new thermoelectric material breaking all records of the amount of energy generated. Such a material could equip the sensors and processors to self-power.

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Thermoelectric materials can convert heat into electrical energy. This is due to the Seebeck effect: if there is a temperature difference between the two ends of such a material, an electrical voltage can be generated and the current can begin to flow. The amount of electrical energy that can be generated at a given temperature difference is measured by the so-called ZT value: the higher the ZT value of a material, the better its thermoelectric properties.

The best thermoelectric materials to date have been measured at ZT values ​​of about 2.5 to 2.8. The physicists of the Technical University of Vienna have succeeded in developing a brand new material with a ZT value of 5 to 6. It is a thin layer of iron, vanadium, tungsten and aluminum applied on a silicon crystal.

The new material is so efficient that it could be used to provide power to sensors or even small computer processors. Instead of connecting small electrical devices to cables, they could generate their own electricity from temperature differences. The study was published in the journal Nature .

A combination of iron, vanadium, tungsten and aluminum

" A good thermoelectric material must have a strong Seebeck effect and must meet two important requirements, which are difficult to reconcile, " says physicist Ernst Bauer of the Institute of Solid Physics at TU Wien. " On the one hand, he must conduct electricity as well as possible; on the other hand, it must conduct the heat as little as possible. This is a challenge because electrical conductivity and thermal conductivity are usually closely related .

At the Christian Doppler laboratory for thermoelectricity, created by Ernst Bauer at TU Wien in 2013, various thermoelectric materials for different applications have been studied in recent years. This research has now revealed a particularly remarkable material: a combination of iron, vanadium, tungsten and aluminum.

Atomic structure of the new material. Credits: B. Hinterleitner et al. 2019

The atoms of this material are generally arranged in a strictly regular manner in a face-centered cubic lattice. The distance between two iron atoms is always the same, and the same goes for the other types of atoms. The whole crystal is therefore perfectly regular, "explains Bauer.

Weyl fermions and low thermal conductivity in crystalline structure

However, when a thin layer of material is applied to silicon, something amazing happens: the structure changes dramatically. Although atoms always form a cubic pattern, they are now arranged in a space-centered structure, and the distribution of different types of atoms becomes completely random.

" Two iron atoms can be assembled next to each other, adjacent sites can be filled with vanadium or aluminum, and there is no longer a rule dictating the location of the next iron atom in the crystal ".

This mixture of regularity and irregularity of the atomic arrangement also modifies the electronic structure, which determines the way in which the electrons move in the solid. " The electric charge moves in a particular way in the material in order to protect it from diffusion processes .  The charges passing through the material are called Weyl Fermions . In this way, a very low electrical resistance is obtained.

Graphics showing the thermoelectric properties of the material. Credits: B. Hinterleitner et al. 2019

On the other hand, the vibrations of the network, which carry the heat from the high temperature zones to the low temperature zones, are inhibited by the irregularities of the crystalline structure. As a result, the thermal conductivity decreases. This is important if the electrical energy has to be generated permanently from a temperature difference - because if the temperature differences could be balanced very quickly and all the material had the same temperature everywhere, the thermoelectric effect 'stop.

Equip interconnected technologies with standalone power

Of course, such a thin layer can not generate a particularly large amount of energy, but it has the advantage of being extremely compact and adaptable. We want to use it to provide energy for sensors and small electronic applications . "

The demand for such small-scale generators is growing rapidly: in the "Internet of Things", more and more devices are connected together online, so they automatically coordinate their behavior with each other. This is particularly promising for future production plants, where one machine must react dynamically to another.

" If you need a lot of sensors in a plant, you can not connect them together. It's much smarter for the sensors to be able to generate their own power using a small thermoelectric device, "concludes Bauer.

Bibliography:

Article: Thermoelectric performance of a metastable thin-film Heusler alloy

Authors: B. Hinterleitner, I. Knapp, E. Bauer

Nature (2019)

Source


Monday, 18 November 2019

New device allows dressing to be applied directly to wounds



Placing bandages or bandages directly on a wound may be difficult in some medical emergencies. The staff must handle the bandages carefully to preserve both sterility and integrity. To get around this problem, a team of bioengineers has developed a portable electrospinning device that, like a spray of paint, can spray a medical dressing directly onto a wound.

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With this new technology, medical personnel can fabricate a dressing with drug delivery capabilities directly to a wound. Electrospinning is a method of developing polymer fibers for a wide variety of applications. If biocompatible materials are used, the fibers produced can be used for biomedical applications.


However, electrospinning requires very high voltages, which makes it dangerous to deposit fiber directly on biological material because of the risk of electrocution it creates.

A group of researchers at Montana Technological University has developed a portable electrospinning device with a confined electric field that can safely deposit bandages and drugs directly onto biological surfaces. The team described the instrument in the journal Journal of Vacuum Science & Technology B .

Spray dressings on the wound like a paint spray

Instead of using the difference in tension between the tool and a surface to deposit the fibers, the new device uses air to spray the fibers on the surface, in the manner of a spray paint. " In spray painting, the pressurized gas forces the particles to go to a surface, creating a kind of deposited material, " said Lane Huston, engineer at Montana Tech.

Demonstration of the dressing projection on a gloved hand, 1 min after projection (A) and 3 min after (B). Credits: Lane G. Huston et al. 2019

As with spray painting, the EStAD device is used by directing its nozzle on the desired surface during operation, which causes the deposition of a mat of fibers on this surface ."

By applying this mechanism similar to aerosol paint, the device can be used to cover wounds and allow controlled release of the drug over time. The deposited fibers adhere to materials containing internal moisture, such as human skin.

The researchers tested the dressing projection on pork skin (top) and on fruits (bottom). Fibers adhere to many types of surfaces. Credits: Lane G. Huston et al. 2019

Although the use of electrospun fibers for effective drug delivery has been established in the past, the foregoing methods required that a wound be placed directly in the path of the electric field. In this configuration, the only safe option is to pre-deposit fibers on a surface, such as parchment paper, to collect them and store them for later use.

Assist medical staff in areas inaccessible to emergency care

The device was tested on a pork skin incision as well as on a gloved human hand. This is the first demonstration of safely depositing fibers delivering the drug directly to the wound site.

The authors hope that this new technology will be used to help doctors, first responders and medical staff treat wounds in rural areas, where immediate medical care may not be readily available.

" The bandage, as well as the drug used, can be chosen on demand if the situation warrants it, thus allowing for modular and adaptable treatment of the accessible drug in isolated areas " Huston. Although the direct deposit method is its preferred application, the researchers' new device can also be used as a traditional table electrospinning device.



Bibliography:

 Article: Combined electrostatic and air driven electrospinning for biomedical applications featured

Journal of Vacuum Science & Technology B 37, 062002 (2019);

https://doi.org/10.1116/1.5122659

Lane G. Hustona), Emily A. Kooistra-Manning,  Jack L. Skinner, and Jessica M. Andriolo

Source


New technology makes it possible to project 3D tactile and sound images


The dream of science fiction writers, holograms are now an active field of research, and more and more advanced prototypes have emerged in recent years. If the technology is not yet to match the holographic projectors of the Star Wars franchise, engineers are continually surpassing new limits. This is the case of a recently developed pseudo-holographic technology, based on an ultrasound system, for projecting shapes and touching them.

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Researchers in Sussex have developed a device that projects animated objects in 3D that can interact with viewers. A demonstration showed a butterfly flapping its wings, a countdown detailed by numbers hanging in the air and a planet Earth in rotation and multicolored. Beyond digital signs and interactive animations, scientists want to use it to visualize and better perceive data.

Although the images are similar, the camera is not the kind of holographic projector for Star Wars movies. Instead, he uses a 3D field of ultrasonic waves to levitate a polystyrene bead and model it at high speed to draw shapes in the air. The study was published in the journal Nature .


3D images created with a pearl and ultrasound

The 2 mm wide bead moves so fast, at speeds approaching 20 km / h, that it traces the shape of an object in less than a tenth of a second. At such a speed, the brain does not see the pearl in motion, only the complete form it creates. The colors are added by integrated LEDs on the screen, which illuminate the pearl as it moves.

Diagram describing the projection device used, as well as some forms created by the device. Credits: Ryuji Hirayama et al. 2019

Because images are created in a 3D space, they can be viewed from any angle. And by carefully controlling the ultrasonic field, scientists can make objects talk or add sound effects and musical accompaniments to moving images. Further manipulation of the sound field allows users to interact with objects and even feel them in their hands.

A step towards next-generation visual entertainment

Sriram Subramanian, team director, explains that besides digital signage, the display could also be used for new forms of visual entertainment. " Let's say you want to create a Harry Potter experience. You can reach out to cast a spell and, as you move it, you can see and feel a glowing ball grow in your palm, and we could also have a sound coming out of it . "

Ryuji Hirayama, who participated in the construction of the screen, says that making such a device was a long-time dream. But he considers that "the display of multimodal acoustic traps" is a step towards more sophisticated systems. " I think that in the future, such screens will allow us to interact with our family and friends as if they were nearby, so we can see them, touch them and hear them ."

Sound and tactile images

The images are created between two horizontal plates dotted with small ultrasonic transducers. These create an inaudible 3D sound field containing a tiny pocket of low pressure air that traps the polystyrene bead.

Move the pouch slightly changing the output of the transducers and the pearl moves with it. The most basic version of the display creates 3D color animations, but the authors describe how they improved the display to produce sounds and tactile responses.

Technology can create a variety of colorful 3D shapes, accompanied by sounds and a tactile response. Credits: Ryuji Hirayama et al. 2019

Speech and other sounds, such as musical accompaniment, were added by vibrating the polystyrene bead when it was around it. Vibrations can be tuned to produce sound waves across the entire range of human hearing, creating, for example, clear, clear speech. Another trick is making touch display by manipulating the ultrasound field to create a virtual "button" in suspension.


Towards advanced holographic technology for everyone

The prototype uses a single bead and can create images in an air cube 10 cm wide. But future displays could use more powerful transducers to create larger animations and use multiple beads at once.

Subramanian stated that existing computer software could be used to prevent small pearls from colliding with each other, although the choreography of lighting several beads in the air is another problem. If technology can be improved, it could transform 3D printing by building objects from tiny droplets of different levitating materials.

" What's interesting about the tactile content is that it was created using ultrasonic waves. Unlike the simple vibrations that most people experience via smartphones or game consoles, ultrasound moves through the air to create precise patterns against the hands. This allows for multimedia experiences where the objects you feel are as rich and vibrant as the ones you see on the screen, "says Euan Freeman of the University of Glasgow.


Julie Williamson, also from Glasgow, says that levitating screens are a first step towards truly interactive 3D displays. " I imagine a future where 3D displays can create experiences that are indistinguishable from the physical objects they simulate ."

This video summarizes the work of researchers and shows technology in action:



Bibliography:

Article: A volumetric display for visual, tactile and audio presentation using acoustic trapping

Authors: Ryuji Hirayama, Diego Martinez Plasencia ', Nobuyuki Masuda' & Sriram Subramanian

DOI:  https://doi.org/1o1038/s41586-019-1739-5

Source

Sunday, 17 November 2019

Another mystery on Mars: Oxygen appears and disappears without explanation



With the mystery of Mars methane still unresolved , the space robot Curiosity brought scientists a new puzzle: Martian oxygen.

The information came by measuring the seasonal levels of all gases in the atmosphere directly above the surface of the Gale Crater, where Curiosity is located. The result is disconcerting.

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On Mars, oxygen, the gas most creatures on Earth use to breathe, behaves in a way that scientists have so far failed to explain through any known chemical process.

Over the course of three Martian years (nearly six years of Earth), a Curiosity instrument called SAM ( Sample Analysis at Mars ) inhaled the air of the Gale Crater and analyzed its composition.

The results confirmed the composition of the Martian surface atmosphere: 95% by volume of carbon dioxide (CO2), 2.6% of molecular nitrogen (N2), 1.9% of argon (Ar), 0.16% of molecular oxygen. (O 2), and 0.06% carbon monoxide (CO).

Measurements also revealed how molecules in Martian air blend and circulate with changes in air pressure throughout the year. These changes are induced when CO2 gas freezes at the poles in winter, lowering air pressure across the planet after air redistribution to maintain pressure balance. When CO2 evaporates in spring and summer and mixes on Mars, the air pressure increases.

The oxygen mystery of Mars

In this environment, data show that nitrogen and argon follow a predictable seasonal pattern, with their concentration increasing and decreasing over the year relative to the amount of CO2 in the air.

Scientists expected oxygen to keep pace, but that is not the case. Instead, the amount of oxygen in the air rises throughout spring and summer by up to 30 percent, and then returns to the levels predicted by known autumn chemistry. This pattern repeats each spring, although the amount of oxygen added to the atmosphere varies, implying that something is producing oxygen and then taking it away.

"The first time we saw this, we were racking our brains," said Sushil Atreya, professor of climate and space science at the University of Michigan.

The team set out to look for possible explanations, first considering the possibility that CO2 or water (H2O) molecules could release oxygen when they separate into the atmosphere, leading to a brief rise in oxygen. But that would consume five times more water than there is in the atmosphere of Mars, and CO2 decomposes too slowly to generate it in such a short time. What about decreasing oxygen? Couldn't solar radiation break oxygen molecules into two atoms, which would then leak into space? No, the scientists concluded, as it would take at least 10 years for oxygen to disappear through this process.

"We are struggling to explain this," said Melissa Trainer, planetary scientist at NASA's Goddard Space Flight Center. "The fact that oxygen behavior doesn't repeat perfectly every season makes us think it's not a problem that has to do with atmospheric dynamics. It has to be a chemical source and a sinkhole that we can't yet explain."

The amount of oxygen in the air increases throughout spring and summer by up to 30 percent, and then returns to the levels predicted by known autumn chemistry

Methane and oxygen, biological and abiotic

The history of oxygen is curiously similar to the methane mystery of Mars. Methane is constantly in the air inside the Gale Crater in such small quantities (0.00000004% on average) that it almost goes unnoticed by the most sensitive instruments ever sent to Mars. Although methane increases and decreases seasonally, it increases abundantly by about 60% in the summer months for unexplained reasons - in fact, methane also fires randomly and dramatically, but no one has yet any idea why.

With the new oxygen discoveries at hand, the NASA team wonders if a chemistry similar to the one that is generating the natural seasonal variations of methane can also explain the variations in oxygen - the two gases even float together, but only occasionally.

"We are beginning to see this tantalizing correlation between methane and oxygen for much of the year on Mars," said Atreya. "I think there's something there. I don't have the answers yet. No one has."

Oxygen and methane can be produced biologically (from microbes, for example) and abiotically (from water and rock-related chemicals). Scientists are considering all options, although we have no convincing evidence of biological activity on Mars.

The Curiosity robot has no instruments that can definitely tell whether the source of methane or oxygen on Mars is biological or geological. With current data, nonbiological explanations are more likely.

Bibliography:

Article: Seasonal variations in atmospheric composition as measured in Gale Crater, Mars

Authors: Melissa G. Trainer, Michael H. Wong, Timothy H. McConnochie, Heather B. Franz, Sushil K. Atreya, Pamela G. Conrad, Franck Lefèvre , Paul R. Mahaffy, Charles A. Malespin, Heidi LK Manning, Javier Martín-Torres, Germán M. Martínez, Christopher P. McKay, Rafael Navarro-González, Alvaro Vicente-Retortillo, Christopher R. Webster, Maria-Paz Zorzano

Magazine : Journal of Geophysical Research: Planets

DOI: 10.1029 / 2019JE006175  

The glowing iris of a patient reveals a severe form of a rare eye syndrome


The human optical system is a complex arrangement of several anatomical components working in concert, and the pathological disorders of which it can be reached are equally complex in their turn. This is particularly the case of a rare disease, the syndrome of dispersion of pigments, which causes a depigmentation of the iris and its transillumination. In other words, exposed to light, the iris glows in a singular way. Recently, a team of doctors described the case of a particularly severe form of this syndrome.

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According to the doctors' analysis, this strange appearance turned out to be the sign of a rare disorder that caused the disappearance of the pigmentation of the eye. The 44-year-old man went to a clinic after moving to a new area to get an appointment with an ophthalmologist.

He said he has a family history of glaucoma, an eye disease that can damage the optic nerve, the bundle of nerve fibers that connects the back of the eye to the brain. This damage is usually caused by increased eye pressure. Indeed, according to the authors of the article published in The New England Journal of Medicine , the man had already been diagnosed with high eye pressure and was taking medication to reduce it.

Pigment dispersion syndrome: transillumination of the iris

Nevertheless, tests revealed that the pressure in his eye was very slightly higher than normal. In addition, when the doctor performed an eye examination using a microscope and a bright light, the evaluation revealed "transillumination of the iris" in both eyes of the patient. In other words, the light shone through the iris. This occurs when sections of pigment are missing at the iris, allowing the light to pass through.

In pigment dispersion syndrome, pigment agglomerates separate from the iris, allowing light to pass through and be reflected in the background. Credits: OPTH

Doctors have diagnosed in humans a syndrome of dispersion of pigments. According to this eye condition, the pigment is detached from the back of the iris. These pigment clumps can clog the drainage system of the eye, causing an increase in eye pressure, which can lead to glaucoma. Pigment dispersion syndrome is rare, although it is more commonly diagnosed in men aged 20 to 30 and may have a genetic component.

In this case, the man was laser treated to open the drainage channels of the blocked eyes. This therapy helps liquids to flow out of the eye and reduces eye pressure. However, patients often need to continue taking pressure-reducing eye medication after surgery, as was the case for this patient.

Source

Saturday, 16 November 2019

Discovery of a new state of matter: metallic Cooper pairs


Described for the first time in 1956, the Cooper pairs are low temperature electron bound states responsible for the superconductivity phenomenon. In today's quantum models, these pairs can be either zero electrical resistance or electrical insulation. However, physicists have discovered a new state of matter in which Cooper pairs conduct electricity while generating some resistance, just like ordinary metal. A phenomenon not foreseen by the physics of condensed matter and which could lead to the development of new electronic devices.

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For years, physicists have assumed that the Cooper pairs, the electron pairs that allow superconductors to drive electricity without resistance, were binary systems. The pairs slide freely, creating a superconducting state, or an insulating state by getting stuck in a material, unable to move.


Pairs of Cooper: they can combine conductivity and electrical resistance

But in a new article published in the journal Science , a team of researchers has shown that Cooper's pairs can also conduct electricity with some resistance, as do ordinary metals. The results describe a new state of matter, according to the researchers, which will require a new theoretical explanation.

" It had been proven that this metallic state would form in thin-film superconductors as they cooled down to their superconducting temperature, but the question of whether this state involved Cooper pairs is an open question, " says Jim. Valles, professor of physics at Brown University.

" We have developed a technique that allows us to answer this question and we have shown that, as a result, Cooper pairs are responsible for carrying the charge in this metallic state. What's interesting is that no one is really sure how it works. This discovery will therefore require more theoretical and experimental work to understand exactly what is happening."

Cooper pairs and superconductivity

Cooper's pairs are named after Leon Cooper, professor of physics at Brown, who won the Nobel Prize in 1972 for describing their role in superconductivity. Resistance is created when electrons vibrate in the atomic network of a material as they move. But when the electrons unite to become Cooper pairs, they undergo a remarkable transformation.

The BCS theory explains the phenomenon of superconductivity by the appearance of Cooper pairs. At very low temperatures, the electrons pair together (b), forming many Cooper pairs within the material (c). These pairs occupy the same fundamental quantum state and form a single quantum wave (d). Cooper pairs are treated as bosons, they obey Bose-Einstein statistics and are not subject to the Pauli exclusion principle. Credits: CNRS


The electrons themselves are fermion s, particles that obey the Pauli exclusion principle, which means that each electron tends to maintain its own quantum state. The Cooper pairs, however, act as bosons, which can share with the same state. This bosonic behavior allows Cooper pairs to coordinate their movements with other sets of Cooper pairs, so as to reduce electrical resistance to zero.


A new bosonic state of Cooper pairs

In 2007, Valles, in collaboration with Jimmy Xu, Professor of Engineering and Physics at Brown, showed that Cooper's pairs could also produce insulating states as well as superconductivity. In very thin materials, rather than moving together, couples stay in place, grouped by islands without means to join those around.

Scanning electron microscope observation of the material used for the experiment: a YBCO superconductor with a network of tiny holes to study the dynamics of the Cooper pairs. Credits: Brown University

For this new study, Valles, Xu and his colleagues searched for non-superconducting metallic Cooper pairs using a technique similar to that which revealed insulators of Cooper pairs. This technique consists of modeling a thin-film superconductor, in this case a high-temperature superconducting yttrium, barium and copper oxide (YBCO), with networks of tiny holes.

When the material is traversed by a current and is exposed to a magnetic field, the charge carriers of the material gravitate around the holes like water surrounding a drain. " We can measure the frequency with which these charges revolve around. In this case, we found that the frequency is compatible with the fact that two electrons circulate at once instead of one. So we can conclude that the charge carriers in this state are Cooper pairs and not electrons, "says Valles.


Towards the potential development of new electronics

The fact that this phenomenon has been detected in a high temperature superconductor will make future research more practical. The YBCO type begins its superconductivity at about -181 ° C and the metal phase begins at a temperature just above that. This higher temperature facilitates the use of spectroscopy and other techniques to better understand what is happening in this metallic phase.

According to the researchers, it may be possible to exploit this bosonic metal state for new types of electronic devices. " The problem with bosons is that they tend to be in a wave state more like electrons. We are talking about a phase and interference similar to that of light. So there may be new ways to move the load in the devices by playing with interference between the bosons "concludes Valles.

Bibliography:

Intermediate bosonic metallic state in the superconductor-insulator transition

Science 14 Nov 2019:
eaax5798
DOI: 10.1126/science.aax5798 

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Friday, 15 November 2019

Artificial intelligence can predict the risk of death in the short term, and researchers are confused about how it works


Artificial intelligence can predict the risk of an individual's short-term death (during the year) by examining the results of his or her heart tests, which sometimes may seem "normal" to doctors. Scientists currently do not know exactly how this AI works to achieve this.

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Brandon Fornwalt, from health care provider Geisinger in Pennsylvania (US) and colleagues, asked artificial intelligence to examine some 1.77 million ECG results from nearly 400,000 people , in order to predict which would be at higher risk of death in the next year.

As a first step, you should know that an ECG records the electrical activity of the heart: it changes in case of heart disease, including before or after heart attacks, in people with atrial fibrillation (a disorder of rhythm cardiac) or other diseases.

The team created two versions of the AI. A first whose algorithm only received the raw ECG data (which reveals the electrical activity over time). And a second who received the ECG data combined with the age and sex of the patients.

The researchers then measured the performance of the AI ​​using a metric called AUC, which defines to what extent a model distinguishes two groups of people: in this case, the patients who died during the year and those who survived ... The AI ​​consistently scored above 0.85 (the perfect score being 1, and a score of 0.5 would not distinguish between the two groups). " The AUCs for the risk rating models currently used by physicians range from 0.65 to 0.8,  " explains Fornwalt.

For comparison, the researchers also created an algorithm based on ECG features currently measured by physicians, such as certain record regularities. " Anyway, the stress-based model has always been better than any model we can build from features we already measure from an ECG, " says Fornwalt.

AI has accurately predicted the risk of death, even among those considered by cardiologists to have a normal ECG result. The three cardiologists who examined the normal-looking ECGs separately were not able to detect the risk profiles identified by the AI.


This discovery suggests that the AI ​​identifies risks that doctors probably can not see, or at least they ignore and think normal,  " says Fornwalt. " Artificial intelligence can potentially teach us things that we may have misunderstood for decades, " he added.

At present, we still do not know which specific patterns are detected by the AI, which makes some doctors reluctant to use such algorithms. "  This research is based on historical data, and it will be important to demonstrate in clinical studies that such an algorithm improves outcomes for patients,  " says Christopher Haggerty, a Fornwalt collaborator.

Two studies on the performance of this new AI will be presented tomorrow, November 16, 2019, at the American Heart Association's Scientific Sessions.

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Thursday, 14 November 2019

The Japanese space probe Hayabusa-2 returns to Earth with samples of an asteroid


Yesterday, the Japanese space probe Hayabusa-2 left its orbit around a distant asteroid and is now heading for the Earth after an exemplary mission. The latter will yield important samples, which could help scientists solve some of the mysteries about the origins of the Solar System.

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For the spacecraft, the long return journey began Wednesday, Nov. 13, 2019, and is expected to reach Earth "by the end of 2020," said Japan Aerospace Exploration Agency (JAXA).

"  We hope that Hayabusa-2 will provide us with new scientific knowledge, " said project director Yuichi Tsuda. The probe will bring back to Earth "carbon and organic matter", which will provide data on "how matter is dispersed in the solar system, why it exists on the asteroid and how it is related to the Earth", Tsuda added.

Below: The images taken by the Hayabusa-2 probe as it leaves the orbit of the asteroid are also displayed in the control room. This is a camera that continues to take scientifically valid photographs, but this time, the pictures were taken for the pleasure of all.



The mission of the Japanese space probe (the size of a large fridge) took her to some 300 million kilometers from the Earth, where she was able to analyze and explore the asteroid Ryugu, whose name means "Palace of Dragon "in Japanese. A name referring to a castle at the bottom of the ocean, in an ancient fable.

In April 2019, the Hayabusa-2 space probe launched an "impactor" on the asteroid in order to "stir" materials that had never been exposed to the atmosphere. The probe was then able to collect dust samples from the surface of the asteroid and never exposed to space vacuum so far. A first !

Scientists hope this will provide clues to the nature of the Solar System at birth, about 4.6 billion years ago. " I feel half-sad and half-determined, so we can do our best to bring the probe home. Ryugu has been at the heart of our daily lives for a year and a half ...  "said Tsuda.

The surface of the asteroid Ryugu, photographed in detail by the Hayabusa-2 probe at 64 and 67 meters altitude. Credits: JAXA

Now, the Hayabusa-2 space probe has begun its return to planet Earth. It will be released permanently from the gravity of the asteroid on November 18, and can start at full speed its main engines at the beginning of December.

Tsuda said the six-year mission, whose total cost is around 30 billion yen (about $ 278 million), had exceeded expectations at the scientific level, but he also admitted that his team had to deal with many technical problems. It took three and a half years for the probe to get to the asteroid, but the return trip should be much shorter because now the Earth and the Ryugu asteroid are much closer (because of their respective current positions).

The Hayabusa-2 probe is expected to deposit the collected samples in the southern Australian desert, but "JAXA is negotiating the details of this part of the mission with the Australian government," Tsuda said.

Note that this probe succeeds the first JAXA asteroid explorer, Hayabusa (which means "hawk" in Japanese). The first probe was sent back to Earth with dust samples of a small asteroid in 2010, despite several setbacks during its epic seven-year odyssey, and was hailed as a scientific triumph.

According to the current plan, Hayabusa-2 will continue its journey into space after depositing its capsule containing the samples on Earth, and could even " perform a new exploration of asteroid, " said spokesman JAXA Keiichi Murakami. "  The team has just started to study what could be done (after the probe has deposited the capsule), but there are no concrete plans for a new destination,  " Tsuda said.

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We finally know more about what would have preceded the Big Bang


In the framework of the "pre-Big Bang" model, implying that the Big Bang is preceded by a first inflation, scientists theorize that the universe was formed in two stages. It would first spread rapidly from a dense mass of matter, then entered a phase of expansion more progressive but very energetic, commonly called "Big Bang". However, the way in which these two stages are related has long been misunderstood by researchers. As part of a new study of this period of the Universe and involving this initial theory, physicists finally think they have solved this mystery remained unanswered for decades, and suggest a way to explain the connection between these two eras primitive.

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During the first primitive period, the Universe would have gone from a small dense mass of matter to nearly a half-million times (x 10 48 ) its size in less than a trillionth of a second (10 -12 s) . In the context of the pre-Big Bang model, this period of rapid inflation was followed by a more gradual but violent expansion phase, the Big Bang.

During the Big Bang, a "ball" of extremely hot matter composed of fundamental particles (protons, neutrons and electrons ) then developed and cooled to form the first atoms, stars and galaxies .

The standard Big Bang theory , which also describes cosmic inflation, remains the most widely supported explanation for the beginnings of our universe. However, scientists are still puzzled as to how these completely different expansion periods are nested.

To solve this mystery, a team of researchers from Kenyon College, the Massachusetts Institute of Technology (MIT) and the University of Leiden in the Netherlands, simulated the critical transition between cosmic inflation and the Big Bang as part of a pre-Big Bang model; a period called "reheat".

" The post-inflation warm-up period defines the conditions of the Big Bang and, in a sense, places the 'Bang' in the Big Bang,  " David Kaiser, a professor of physics at MIT , said in a statement . " It's a time of transfer, when hell is unleashed and the matter behaves in a complex way  ."

The history of the universe (standard model of the Big Bang). Above, inflation, which generates two types of waves: gravitational waves and density waves. Below, the radius of the visible Universe, from the Big Bang (t0), then the inflation (white / yellow), the formation of the protons, the beginning of the nuclear fusion, the end of the nuclear fusion (3 minutes), up to the 13.8 billion years that the Universe has today. Credits: DrBogdan / Yinweichen / Wikimedia

When the Universe developed into a "fraction of a second" during cosmic inflation, all existing matter spread out in all directions, leaving in space an empty, cold place, devoid of "soup." primordial "(dense and hot cluster of particles) necessary to start the Big Bang. During the warm-up period, it is thought that the energy that propelled inflation broke down into particles, said Rachel Nguyen, PhD student in physics at the University of Illinois and lead author of the study.

Once these particles are produced, they bounce off and bump into each other, transferring inertia and energy,  " Nguyen said. " And this is what thermises and warms the universe to define the initial conditions of the Big Bang  ".

In their model, Nguyen and his colleagues simulated the behavior of an exotic form of matter called inflaton. Scientists believe that the scalar field of this material, which is similar in nature to that of the Higgs boson, is responsible for creating the energy field that has led to cosmic inflation.

Their model showed that, under proper conditions, the hypothetical scalar field energy could be efficiently redistributed to create the diversity of particles needed to warm the primitive Universe. The results of the study are available in Physical Review Letters.

Gravity: it would react differently to very high energies

" When we study the primitive universe, we perform an experiment with particles at very high temperatures,  " said Tom Giblin, an associate professor of physics at Kenyon College in Ohio and co-author of the study. " The transition from the cold inflationary period to the warm period should contain essential evidence about the particles that actually exist at these extremely high energies."

A fundamental question that still afflicts physicists is how gravity behaves to the extreme energies present during inflation. Albert Einstein's theory of general relativity defines that all matter is affected by gravity in the same way, where the force of gravity is constant, regardless of the energy of the particle. However, because of the strange properties of quantum mechanics, scientists now think that at very high energies matter reacts differently to gravity.

The team incorporated this hypothesis into their model by modifying the interaction force of particles with gravity. They then discovered that the more they increased the force of gravity, the more the inflaton effectively transferred energy to produce the Hot Bang's field of hot material particles.

Additional clues needed to support the model

" The universe contains so many secrets, encoded in a very complex way  ," said Giblin. " It's our job to study the nature of reality by offering a 'decoding device' - a way to extract information from the universe. For this, we use simulations to predict what the universe should look like, so that we can actually begin to decode it. This warm-up period should have left an imprint somewhere. We just have to find it  . "

But identifying this footprint could prove to be a very complex task. Our first glimpse of the Universe is a "bubble of radiation" left a few hundred thousand years after the Big Bang: the cosmic microwave background (CMB). However, the CMB only evokes the state of the universe during the first critical seconds of its birth. Physicists hope that future observations of gravitational waves will provide the additional clues needed to support their model.


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Discover the Persian 11th Century Canon of Medicine, “The Most Famous Medical Textbook Ever Written”



It may never lend a catchy title to a steamy TV hospital drama, but Avicenna’s 11th-century Canon of Medicine has the distinction of being “the most famous medical textbook ever written.” It has remained, as William Osler wrote in a 1918 Yale lecture, “a medical bible for a longer time than any other work.” Completed in 1025, the compendium drew Greek, Roman, Arabic, Indian, and Chinese medical science together in five dense volumes of material informed by the theories of Galen and structured by the systematic philosophy of Aristotle, whom Avicenna (Abū-ʿAlī al-Ḥusayn ibn-ʿAbdallāh Ibn-Sīnā) called “The First Teacher.”

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Translated into Latin in the 12th century and “often revised,” the Canon, notes the Stanford Encyclopedia of Philosophy, “formed the basis of medical instruction in European Universities until the 17th century.” A copy of excerpts from the text has even been found translated into 15th-century Irish, demonstrating a link between medieval Ireland and the Islamic world. Avicenna’s influence generally on the intellectual culture of medieval and early modern Europe and the Arab-speaking world can hardly be overstated.


Born in 980 A.D., the Persian philosopher and physician was instrumental in the recovery of Hellenic thought, first in the Islamic world, then later in Europe. He took to the study of medicine very early in his extraordinary career. “I became proficient in it in the shortest time,” he says, “until the excellent scholars of medicine began to study under me.” He also became a practicing physician, inspired by a desire to put his learning to the test. “Through my experiences I acquired an amazing practical knowledge and ability in methods of treatment.”

The practical knowledge in The Canon of Medicine was largely the basis for its continued use for centuries. It lays out rules for drug testing, which include an insistence on human trials and the importance of conducting multiple experiments and showing consistent results across cases. Like most classical scientific texts, it weaves empirical observation with metaphysics, theology, scholastic speculation, and cultural biases particular to its time and place. But the practical outlines of its medical knowledge transcend its archaisms.

The work presents “an integrated view of surgery and medicine,” notes the Journal of the Royal Society of Medicine. In addition to his imminently useful guide for assessing the effects of drugs, Ibn Sina tells his readers “how to judge the margin of healthy tissue to remove with an amputation,” an intervention that has saved countless numbers of lives. “The enduring respect in the 21st century for a book written a millennium earlier is testimony to Ibn Sina’s achievement.”


One of the defining features of the text is its insistence on the practice of medicine as a systematic scientific pursuit of equal merit to the theorizing of it:

    Someone might say to us that medicine is divided into theoretical and practical parts and that, by calling it a science, we have considered it as being all theoretical. To this we respond by saying that some arts and philosophy have theoretical and practical parts, and medicine, too, has its theoretical and practical parts. The division into theoretical and practical parts differs from case to case, but we need not discuss these divisions in disciplines other than medicine. If it is said that some parts of medicine are theoretical and other parts are practical, this does not mean that one part teaches medicine and the other puts it into practice – as many researchers in this subject believe. One should be aware that the intention is something else: it is that both parts of medicine are science, but one part is the science dealing with the principles of medicine, and the other with how to put those principles into practice.

Of course, much of the medical theory in the Canon has been disproven, but it remains of keen interest to students of the history of medicine and of European and Islamic intellectual cultural history more generally. Avicenna towers above his contemporaries, yet his work also bears witness to the larger “intellectual climate of his time,” as the site Medical History Tour points out. He emerged from a milieu “shaped by centuries of translation and cross-cultural scholarship” of Greek, Roman, Indian, Chinese, Persian, and Arabic literature. “A rich Persian medical tradition began 200 years before Avicenna.”

Nonetheless, “however the world came by the genius of Avicenna, his influence was lasting,” with The Canon of Medicine remaining a definitive “best practices” guide to medicine for centuries after its composition. See full scans of several Arabic copies of the text at the Library of Congress’s World Digital Library and read a full English translation of the massive 5-volume work, with its extensive chapters on definitions, anatomy, etiology, and treatments, at the Internet Archive.

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Tuesday, 12 November 2019

Two daily cleaning products have generated toxic fumes in a restaurant, killing an employee


The manager of a Buffalo Wild Wings restaurant died after being exposed to toxic fumes generated by blending two common cleaning products. Other employees (more than a dozen) were also affected by the toxic releases.

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On Thursday, November 7th, an employee of a Buffalo Wild Wings in Burlington, Mass., Began cleaning the back of the restaurant with a common cleaner called "Super 8". The incident occurred shortly thereafter.

The solution of Super 8 is based on sodium hypochlorite, a disinfectant and bleaching agent (used especially in the form of bleach). Its unique use does not represent a danger. However, unbeknownst to the employee, another acid-based cleaner, the Scale Kleen, had been spilled on the floor shortly before, according to NBC News .

A deadly mixture

Blending the two chemicals produced a substance that "turned green and started to bubble," said Michael Patterson, Burlington Fire Chief.

The first exposed employee quickly developed eye burns and began to experience breathing difficulties. He then left the premises. The restaurant manager then took over, trying to scrape the mixture, but he too developed severe symptoms, making him unable to continue.

The manager, Ryan Baldera, 32, died shortly after at the hospital, according to the local newspaper NBC Boston . Thirteen other people, also exposed to toxic fumes, were taken care of.

The chemical accident occurred at a Buffalo Wild Wings in Burlington, Massachusetts (United States). Credits: Google Street View

Common cleaning products can be dangerous or even deadly when mixed incorrectly. For example, bleach can react with ammonia, acids and other cleaners. The resulting reactions can give rise to potentially life-threatening toxic fumes.

Responsible potential: chlorine gas


When bleach is mixed with acid (such as vinegar or chemicals found in some window cleaners, drains and toilet bowls), chlorine gas is produced. Exposure to chlorine usually causes irritation of the eyes, throat and nose, causing coughing and breathing problems. Moreover, it should be known that due to its toxicity, the dichlore was one of the first combat gases used during the First World War.

At high concentrations, chlorine gas can cause severe breathing difficulties and fluid production in the lungs. At very high concentrations, a deep emanation can cause death.

A team specialized in dangerous substances was convened to treat the premises of the restaurant, which was temporarily closed by the city. Occupational Safety and Health Administration (OSHA) is also investigating the accident.

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