Física Interessante
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A Física interessante, sim! É incrível como maus professores transformaram a Física naquele amontoado de fórmulas sem sentido! A Física é mais surpreendente do que a Ficção Científica! Mais incrível que Arquivo X. Newton, Einstein ou Gauss fazem parte da nossa cultura tanto quanto os Beatles, Picasso ou Marx.
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Without a Proof, Mathematicians Wonder How Much Evidence Is Enough 

Without a Proof, Mathematicians Wonder How Much Evidence Is Enough  | Física Interessante | Scoop.it
Alexander Smith’s work on the Goldfeld conjecture reveals fundamental characteristics of elliptic curves.

 

Four researchers have recently come out with a model that upends the conventional wisdom in their field. They have used intensive computational data to suggest that for decades, if not longer, prevailing opinion about a fundamental concept has been wrong.

 

These are not biologists, climatologists or physicists. They don’t come from a field in which empirical models get a say in determining what counts as true. Instead they are mathematicians, representatives of a discipline whose standard currency — indisputable logical proof — normally spares them the kinds of debates that consume other fields. Yet here they are, model in hand, suggesting that it might be time to re-evaluate some long-held beliefs.

 

The model, which was posted in 2016 and is forthcoming in the Journal of the European Mathematical Society, concerns a venerable mathematical concept known as the “rank” of an algebraic equation. The rank is a measurement that tells you something about how many of the solutions to that equation are rational numbers as opposed to irrational numbers. Equations with higher ranks have larger and more complicated sets of rational solutions.

 

Since the early 20th century mathematicians have wondered whether there is a limit to how high the rank can be. At first almost everyone thought there had to be a limit. But by the 1970s the prevailing view had shifted — most mathematicians had come to believe that rank was unbounded, meaning it should be possible to find curves with infinitely high ranks. And that’s where opinion stuck even though, in the eyes of some mathematicians, there weren’t any strong arguments in support of it.

 

“It was very authoritarian the way people said it was unbounded. But when you looked into it, the evidence seemed very slim,” said Andrew Granville, a mathematician at the University of Montreal and University College London. Now evidence points in the opposite direction. In the two years since the model was released, it has convinced many mathematicians that the rank of a specific type of algebraic equation really is bounded. But not everyone finds the model persuasive. The lack of resolution raises the kinds of questions that don’t often attend mathematical results — what weight should you give to empirical evidence in a field where all that really counts is proof?

 

“There is really no mathematical justification for why this model is exactly what we want,” said Jennifer Park, a mathematician at Ohio State University and a co-author of the work. “Except that experimentally, a lot of things seem to be working out.”


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CRISPR might soon create spicy tomatoes by switching on their chili genes 

CRISPR might soon create spicy tomatoes by switching on their chili genes  | Física Interessante | Scoop.it

Looking for perfect heat and lots of it? Gene engineers in Brazil think they might be able to create eye-watering tomatoes.

 

Even though chili peppers and tomato plants diverged from a common ancestor millions of years ago, tomatoes still possess the genetic pathway needed to make capsaicinoids, the molecules that make chilis hot.

 

Now, Agustin Zsögön from the Federal University of Viçosa in Brazil writes in the journal Trends in Plant Science that gene-editing tools like CRISPR could turn it back on.

 

Spicy biofactories: Tomatoes are much easier to grow than peppers, so making them hot could turn them into spice factories. “Capsaicinoids are very valuable compounds; they are used in [the] weapons industry for pepper spray, they are also used for anaesthetics [and] there is some research showing that they promote weight loss,” he told the Guardian.

 

Strange fruit: Tomatoes are not the first food that scientists have suggested could be given an unusual new twist using CRISPR. Sweeter strawberriesnon-browning mushrooms, and tastier ground-cherries have all been either attempted or mooted in the past.


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Matter Sucked in by Black Holes May Travel into the Future to Get Spit Back Out 

Matter Sucked in by Black Holes May Travel into the Future to Get Spit Back Out  | Física Interessante | Scoop.it
A new theory tries to explain the mysterious phenomena that exists at the center of black holes.

 

Black holes are among the most mysterious places in the universe; locations where the very fabric of space and time are warped so badly that not even light can escape from them. According to Einstein's theory of general relativity, at their center lies a singularity, a place where the mass of many stars is crushed into a volume with exactly zero size. However, two recent physics papers, published on Dec.10 in the journals Physical Review Letters and Physical Review D, respectively, may make scientists reconsider what we think we know about black holes. Black holes might not last forever, and it's possible that we've completely misunderstood their nature and what they look like at the center, according to the papers. [read: Stephen Hawking's Most Far-Out Ideas About Black Holes]

 

Astronomers and physicists have long held that the idea of a singularity simply must be wrong. If an object with mass has no size, then it has infinite density. And, as much as researchers throw around the word "infinity," infinities of that kind don't exist in nature. Instead, when you encounter an infinity in a real, physical, science situation, what it really means is that you've pushed your mathematics beyond the realm where they apply. You need new math.

 

It's easy to give a familiar example of this. Newton's law of gravity says that the strength of the gravitational attraction changes as one over the distance squared between two objects. So if you took a ball located far from Earth, it would experience a certain weight. Then, as you brought it closer to Earth, the weight would increase. Taking that equation to the extreme, as you brought the object near to the center of Earth, it would experience an infinite force. But it doesn't. Instead, as you bring the object close to the surface of Earth, Newton's simple law of gravity no longer applies. You have to take into account the actual distribution of Earth’s mass, and this means that you need to use different and more complex equations that predict different behavior. Similarly, while Einstein's theory of general relativity predicts that a singularity of infinite density exists at the center of black holes, this can't be true. At very small sizes, a new theory of gravity must come into play. This theory is called quantum gravity.


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Rare microbe leads scientists to discover new branch on the tree of life 

Rare microbe leads scientists to discover new branch on the tree of life  | Física Interessante | Scoop.it

Canadian researchers have discovered a new kind of organism that's so different from other living things that it doesn't fit into the plant kingdom, the animal kingdom, or any other kingdom used to classify known organisms. Two species of the microscopic organisms, called hemimastigotes, were found in dirt collected on a whim during a hike in Nova Scotia by Dalhousie University graduate student Yana Eglit.

 

A genetic analysis shows they're more different from other organisms than animals and fungi (which are in different kingdoms) are from each other, representing a completely new part of the tree of life, Eglit and her colleagues report in Nature.,

 

"They represent a major branch that we didn't know we were missing," said Dalhousie biology professor Alastair Simpson, Eglit's supervisor and co-author of the new study. "There's nothing we know that's closely related to them." In fact, he estimates you'd have to go back a billion years — about 500 million years before the first animals arose — before you could find a common ancestor of hemimastigotes and any other known living things.

 

The hemimastigotes analyzed by the Dalhousie team were found by Eglit during a spring hike with some other students along the Bluff Wilderness Trail outside Halifax a couple of years ago. She often has empty sample vials in her pockets or bags, and scooped a few tablespoons of dirt into one of them from the side of the trail. Back at the lab, she soaked the soil in water, which often revives microbes that have gone dormant, waiting for the next big rainstorm. Over the next few weeks, she checked on the dish through a microscope to see what might be swimming around.

 

Then, one day, about three weeks later, she saw something that caught her eye — something shaped like the partially opened shell of a pistachio. It had lots of hairs, called flagella, sticking out. Most known microbes with lots of flagella move them in co-ordinated waves, but not this one, which waved them in a more random fashion.  "It's as if these cells never really learned that they have many flagella," Eglit said with a laugh. She had seen something with that strange motion once before, a few years ago, and recognized it as a rare hemimastigote.

 

Hemimastigotes were first seen and described in the 19th century. But at that time, no one could figure out how they fit into the evolutionary tree of life. Consequently, they've been "a tantalizing mystery" to microbiologists for quite a long time, Eglit said.


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Measles cases spike globally due to gaps in vaccination coverage, WHO reports 

Measles cases spike globally due to gaps in vaccination coverage, WHO reports  | Física Interessante | Scoop.it
Reported measles cases spiked in 2017, as multiple countries experienced severe and protracted outbreaks of the disease. This is according to a new report published today by leading health organizations.

 

Because of gaps in vaccination coverage, measles outbreaks occurred in all regions, while there were an estimated 110 000 deaths related to the disease.  Using updated disease modelling data, the report provides the most comprehensive estimates of measles trends over the last 17 years. It shows that since 2000, over 21 million lives have been saved through measles immunizations. However, reported cases increased by more than 30 percent worldwide from 2016. 

 

The Americas, the Eastern Mediterranean Region, and Europe experienced the greatest upsurges in cases in 2017, with the Western Pacific the only World Health Organization (WHO) region where measles incidence fell. “The resurgence of measles is of serious concern, with extended outbreaks occurring across regions, and particularly in countries that had achieved, or were close to achieving measles elimination,” said Dr Soumya Swaminathan, Deputy Director General for Programmes at WHO. “Without urgent efforts to increase vaccination coverage and identify populations with unacceptable levels of under-, or unimmunized children, we risk losing decades of progress in protecting children and communities against this devastating, but entirely preventable disease.”

 

Measles is a serious and highly contagious disease. It can cause debilitating or fatal complications, including encephalitis (an infection that leads to swelling of the brain), severe diarrhoea and dehydration, pneumonia, ear infections and permanent vision loss. Babies and young children with malnutrition and weak immune systems are particularly vulnerable to complications and death.

 

The disease is preventable through two doses of a safe and effective vaccine. For several years, however, global coverage with the first dose of measles vaccine has stalled at 85 percent. This is far short of the 95 percent needed to prevent outbreaks, and leaves many people, in many communities, susceptible to the disease. Second dose coverage stands at 67 percent.

 

“The increase in measles cases is deeply concerning, but not surprising,” said Dr Seth Berkley, CEO of Gavi, the Vaccine Alliance. “Complacency about the disease and the spread of falsehoods about the vaccine in Europe, a collapsing health system in Venezuela and pockets of fragility and low immunization coverage in Africa are combining to bring about a global resurgence of measles after years of progress. Existing strategies need to change: more effort needs to go into increasing routine immunization coverage and strengthening health systems. Otherwise we will continue chasing one outbreak after another.”


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Re-programming the body's energy pathway boosts kidney self-repair 

Re-programming the body's energy pathway boosts kidney self-repair  | Física Interessante | Scoop.it
A team of researchers led by Jonathan Stamler, MD, of Case Western Reserve University School of Medicine and University Hospitals Cleveland Medical Center, has discovered a pathway for enhancing the self-repair efforts of injured kidneys The finding may pave the way for new drugs to stop or even reverse the progression of serious kidney disease in humans—and other potentially lethal conditions of the heart, liver, and brain as well.

 

 

Kidneys filter waste and excess fluid from the blood, excreting the unsafe molecules in urine. As kidneys are injured or fail, waste builds up, potentially resulting in death. The newly-discovered pathway involves reprogramming the body's own metabolism in order to save damaged kidneys. Normally, a process called glycolysis converts glucose from food into energy, which is necessary for life to continue. But the new discovery shows that when tissue is injured, the body can switch the process in to one of repair to damaged cells.

 

Until now, the mechanisms by which the body switches between energy generation (for maximal performance) and repair (in injury) were poorly understood. Moreover, the body rarely maximizes the potential for repair, usually favoring energy production. In the new findings, published online today and in the November 29th issue of Nature, the science team discovered how to intensify the switching process, resulting in a cascade of tissue-repair molecules that successfully stopped progression of kidney disease in mice.

 

When injured, the body slows down use of sugar for energy, using it for repair instead," said Stamler. "We show that we can control and amplify this process by shunting glucose away from energy generation into pathways that protect and repair cells. By giving a 'lift and push' to the body's own self-healing we improve lifespan of injured animals. We can think of it as a blueprint for new lines of future therapy against injured and damaged tissue." Normally, when cells break down fat, sugars, and proteins into glucose, the three substances are converted into intermediate products that move into the mitochondria, the powerhouse of cells, providing fuel for life. Stamler's team reports that things work very differently in injured tissues: in the kidneys for example, the body triggers a "Plan B," converting the glucose into new molecules that carry out cell repair instead.

 

Stamler and colleagues found that a protein called PKM2 controls whether fuel (glucose) is used to power the cell or shift into repair mode. Disabling PKM2 resulted in a significant increase in cell-repair and a concomitant decrease in energy-generation. "After injury or disease, the body tries to disable the PKM2 protein in order to divert glucose into recovery mode. In our research, we amplified its inhibition. This resulted in significant protection against kidney injury in mice."

 

A key molecule in the process is nitric oxide (NO). It was already known that NO protects kidneys and other tissue. NO is the active ingredient in nitroglycerine used for addressing heart disease so it was assumed that NO worked by dilating blood vessels. But the research team found that NO attached to a critical molecule called Co-enzyme A—known as a metabolite—linked to the glycolysis and energy production. Co-enzyme A binds to and transports NO into many different proteins, including PKM2, "turning them off." This determines whether the kidney cells are using their pathways for energy or repair.

 

In addition to finding that adding NO to PKM2 activates repair, Stamler's team found that a protein called AKR1A1 subsequently removes the NO from PKM2, re-activating a robust energy-generating process. This reversal, after healing is complete, allows glucose to be converted efficiently into fuel. "This helps explain why people regain the capacity to do strenuous activity after they recover from an injury or illness," said Stamler. When the research team disabled AKR1A1, the kidneys remained in repair mode and were highly protected from disease.


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Spotting nature's own evolution of quantum tricks could transform quantum technology 

Spotting nature's own evolution of quantum tricks could transform quantum technology  | Física Interessante | Scoop.it

A new test to spot where the ability to exploit the power of quantum mechanics has evolved in nature has been developed by physicists at the University of Warwick.

 

The test identifies a tell-tale hallmark of quantum coherence, classifying the properties of particles in a quantum state that are interacting with a real-world environment. The test should allow scientists to quantify and track quantum coherence in the natural world using laboratory experiments.

 

Published this week in the journal Physical Review A, the theoretical work could lead to experiments that help solve the debate on whether biological processes exploit quantum mechanics to their advantage, and whether evolution could provide us with a template for quantum technologies such as computers, sensors and energy sources.

 

Microscopic particles in a quantum state are very difficult to spot as the act of observing them changes their state. These stealthy particles can exist in many locations or configurations simultaneously, a feature known as quantum coherence.

 

The effect underpins technologies such as quantum computers, quantum sensors and quantum communication systems, which use ordered systems isolated from the rest of the world. However, whether quantum coherence exists in the noisier and messier real world is more difficult to identify.

 

The test involves a procedure to destroy quantum coherence, and then to observe the change in later measurements. Where a measurably large impact is observed, scientists can demonstrate that there must have been quantum coherence in the system. The new work clarifies the possible exceptions to this conclusion, which depend on how quickly the special procedure can destroy the coherence.

 

Dr. George Knee, 1851 Royal Commission Research Fellow from the University's Department of Physics, said: "To demonstrate the presence of quantum coherence in a biological system would constitute a paradigm shift, away from the idea that only humans have the ability to engineer systems capable of exhibiting and exploiting quantum coherence. It would also be a step toward the Schroedinger's Cat thought experiment, where a living organism is placed in a state where it is, quantum coherently, both dead and alive."

 

Co-author Dr. Animesh Datta said: "The results from this test will be valuable in improving our understanding of how chemistry and biology works, and may allow us to answer the question of whether quantum physics has played a part in evolutionary processes."


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How biologists are creating life-like cells from scratch

How biologists are creating life-like cells from scratch | Física Interessante | Scoop.it
Built from the bottom up, synthetic cells and other creations are starting to come together and could soon test the boundaries of life.

 

There were just eight ingredients: two proteins, three buffering agents, two types of fat molecule and some chemical energy. But that was enough to create a flotilla of bouncing, pulsating blobs — rudimentary cell-like structures with some of the machinery necessary to divide on their own. To biophysicist Petra Schwille, the dancing creations in her lab represent an important step towards building a synthetic cell from the bottom up, something she has been working towards for the past ten years, most recently at the Max Planck Institute of Biochemistry in Martinsried, Germany. “I have always been fascinated by this question, ‘What distinguishes life from non-living matter?’” she says. The challenge, according to Schwille, is to determine which components are needed to make a living system. In her perfect synthetic cell, she’d know every single factor that makes it tick.

 

Another key to making a cell is getting the software right. Enabling a synthetic cell to follow scientists’ instructions and to replicate itself will require some way of storing and retrieving information. For living systems, this is done by genes — from hundreds for some microbes, to tens of thousands for humans. How many genes a synthetic cell will need to run itself is a matter of healthy debate. Schwille and others would like to keep it in the neighbourhood of a few dozen. Others think that synthetic cells need 200–300 genes.

 

Some have chosen to start with something living. Synthetic biologist John Glass and his colleagues at the J. Craig Venter Institute (JCVI) in La Jolla, California, took one of the smallest-known microbial genomes on the planet, that of the bacterium Mycoplasma mycoides, and systematically disrupted its genes to identify the essential ones. Once they had that information, they chemically stitched together a minimal genome in the laboratory.

 

This synthesized genome contained 473 genes — about half of what was in the original organism — and it was transplanted into a related bacterial species, Mycoplasma capricolum9. In 2016, the team showed that this minimal synthetic genome could ‘boot up’ a free-living, although slow-growing organism10. Glass thinks that it will be hard to decrease that number much more: take any gene away, and it either kills the cells or slows their growth to near zero, he says.

 

He and his JCVI colleagues are compiling a list of ‘cellular tasks’ based on the latest version of their creation, JCVI-syn3.0a, which could act as a blueprint of a cell’s minimal to-do list. But for about 100 of these genes, they can’t identify what they do that makes them essential. As a next step, and supported by an NSF grant of nearly $1 million, Glass and Adamala will attempt to install the JCVI-syn3.0a genome into a synthetic liposome containing the machinery needed to convert DNA into protein, to see whether it can survive. In that case, both the software and the hardware of the cell would be synthetic from the start.

 

If it could grow and divide, that would be a tremendous step. But many argue that to truly represent a living system, it would also have to evolve and adapt to its environment. This is the goal with the most unpredictable results and also the biggest challenges, says Schwille. “A thing that just makes itself all the time is not life — although I would be happy with that!” she says. “For a cell to be living, it needs to develop new functionality.”

 

Glass’s team at the JCVI has been doing adaptive laboratory evolution experiments with JCVI-syn3.0a, selecting for organisms that grow faster in a nutrient-rich broth. So far, after about 400 divisions, he and his team have obtained cells that grow about 15% faster than the original organism. And they have seen a handful of gene-sequence changes popping up. But there’s no evidence yet of the microbe developing new cellular functions or increasing its fitness by leaps and bounds.

 

A little bit of messiness in biological systems is what allows them to improve their performance. Synthetic cells could lead to insights about how life might look on other planets. And synthetic bioreactors under a researcher’s complete control might offer new solutions to treating cancer, tackling antibiotic resistance or cleaning up toxic sites. Releasing such an organism into the human body or the environment would be risky, but a top-down engineered organism with unknown and unpredictable behaviors might be even riskier.

 

Synthetic living cells can also bring other philosophical and ethical questions: Will this be a life? Will it be autonomous? Will we control it? These conversations should take place between scientists and the public, before going too far into the projects. As for concerns that synthetic cells will run amok, many scientists are less worried. Many synthetic biologists will keep pushing ahead exploring the frontiers of life. The timing seems right, and scientists have the genomes, the parts list to work with. The minimal cell needs only a few hundred genes to have something that looks sort of alive. Hundreds of parts is a tremendous challenge, but it’s not thousands and that’s very exciting.

 

Nature 563, 172-175 (2018).

doi: 10.1038/d41586-018-07289-x

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What makes a mammal a mammal? Our spine, say scientists 

What makes a mammal a mammal? Our spine, say scientists  | Física Interessante | Scoop.it
Mammals are unique in many ways. We're warm-blooded and agile in comparison with our reptilian relatives.

But a new study, funded by the National Science Foundation (NSF) and led by Harvard University researchers Stephanie Pierce and Katrina Jones, suggests we're unique in one more way -- the makeup of our spines. The researchers describe their finding in a paper published this week in the journal Science.

"The spine is basically like a series of beads on a string, with each bead representing a single bone -- a vertebra," said Pierce, curator of vertebrate paleontology at Harvard. "In most four-legged animals, like lizards, the vertebrae all look and function the same.

"But mammal backbones are different. The different sections or regions of the spine -- like the neck, thorax and lower back -- take on very different shapes. They function separately and so can adapt to different ways of life, like running, flying, digging and climbing."

While mammal backbones are specialized, the regions that underlie them were believed to be ancient, dating back to the earliest land animals.

Mammals made the most of the existing anatomical blueprint, or so scientists believed. However, the new study is challenging this idea by looking into the fossil record.

"There are no animals alive today that record the transition from a 'lizard-like' ancestor to a mammal," said Jones, lead author of the study. "To do that, we have to dive into the fossil record and look at the extinct forerunners of mammals, the non-mammalian synapsids."

These ancient ancestors hold the key to understanding the origin of mammal-specific characteristics, including the spine.

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The role of random nanostructures for the omnidirectional anti-reflection properties of the glasswing butterfly 

The role of random nanostructures for the omnidirectional anti-reflection properties of the glasswing butterfly  | Física Interessante | Scoop.it

Glasswing butterflies develop nanostructures on their wings that actually give them “anti-reflective” properties. This allows them to reduce the amount of light bouncing their wings & remain transparent in a terrestrial environment, something few animals on the planet can do.

 

The glasswing butterfly (Greta oto) has, as its name suggests, transparent wings with remarkable low haze and reflectance over the whole visible spectral range even for large view angles of 80°. This omnidirectional anti-reflection behaviour is caused by small nanopillars covering the transparent regions of its wings. In difference to other anti-reflection coatings found in nature, these pillars are irregularly arranged and feature a random height and width distribution. Scientists now simulate the optical properties with the effective medium theory and transfer matrix method and show that the random height distribution of pillars significantly reduces the reflection not only for normal incidence but also for high view angles.


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Mum’s a Neanderthal, Dad’s a Denisovan: Researchers Sequence First Ancient Human Hybrid 

Mum’s a Neanderthal, Dad’s a Denisovan: Researchers Sequence First Ancient Human Hybrid  | Física Interessante | Scoop.it
Genetic analysis uncovers a direct descendant of two different groups of early humans.

 

A female who died around 90,000 years ago was half Neanderthal and half Denisovan, according to genome analysis of a bone discovered in a Siberian cave. This is the first time scientists have identified an ancient individual whose parents belonged to distinct human groups. The findings were published on 22 August in Nature1.

 

“To find a first-generation person of mixed ancestry from these groups is absolutely extraordinary,” says population geneticist Pontus Skoglund at the Francis Crick Institute in London. “It’s really great science coupled with a little bit of luck.” The team, led by palaeogeneticists Viviane Slon and Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, conducted the genome analysis on a single bone fragment recovered from Denisova Cave in the Altai Mountains of Russia. This cave lends its name to the ‘Denisovans’, a group of extinct humans first identified on the basis of DNA sequences from the tip of a finger bone discovered [2] there in 2008. The Altai region, and the cave specifically, were also home to Neanderthals.

 

Given the patterns of genetic variation in ancient and modern humans, scientists already knew that Denisovans and Neanderthals must have bred with each other — and with Homo sapiens. But no one had previously found the first-generation offspring from such pairings, and Pääbo says that he questioned the data when his colleagues first shared them. “I thought they must have screwed up something.” Before the discovery of the Neanderthal–Denisovan individual, whom the team has affectionately named Denny, the best evidence for so close an association was found in the DNA of a Homo sapiens specimen who had a Neanderthal ancestor within the previous 4–6 generations [3].


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DNA Nanostructures Strengthened to Survive Harsh Environments 

DNA Nanostructures Strengthened to Survive Harsh Environments  | Física Interessante | Scoop.it

Enhanced durability now makes DNA nanostructures functional for in vivo applications About six years ago, Hendrik Dietz and his team of researchers at Technische Universitaet Muenchen (TUM) finally proved that DNA can assemble an object so that all the parts fit together with atomic precision. Not only that, but Dietz’s research shortened the process from weeks to just minutes.

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These beautiful maps show our impact on the planet

These beautiful maps show our impact on the planet | Física Interessante | Scoop.it

From global shipping to undersea cables and population density, these maps highlight our impact on the planet.

 

In a short amount of time, humans have changed the face of planet Earth. Our impact has been so profound, in fact, that scientists have declared the dawn of the Anthropocene epoch, or the age of human influence. Today’s ambitious graphic comes to us from Reldresal, and it looks at this human footprint from a number of different angles. Here are some of the ones we found most interesting.

POPULATION DENSITY

While there are humans present in nearly every part of the world, the overall distribution of population is far from even. As the map above vividly demonstrates, humans cluster in specific places that have the right conditions to support a large population. Massive river deltas such as Ganges-Brahmaputra (Bangladesh) and the Nile (Egypt) are obvious bright spots on the map. Not surprisingly, sparsely populated countries like Australia and Canada are nearly indistinguishable as most people cluster in more habitable places.


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New Caledonian crows infer the weight of objects from observing their movements in a breeze 

New Caledonian crows infer the weight of objects from observing their movements in a breeze  | Física Interessante | Scoop.it

Humans use a variety of cues to infer an object's weight, including how easily objects can be moved. For example, if we observe an object being blown down the street by the wind, we can infer that it is light. A team of scientists tested now whether New Caledonian crows make this type of inference. After training that only one type of object (either light or heavy) was rewarded when dropped into a food dispenser, birds observed pairs of novel objects (one light and one heavy) suspended from strings in front of an electric fan. The fan was either on—creating a breeze which buffeted the light, but not the heavy, object—or off, leaving both objects stationary. In subsequent test trials, birds could drop one, or both, of the novel objects into the food dispenser. Despite having no opportunity to handle these objects prior to testing, birds touched the correct object (light or heavy) first in 73% of experimental trials, and were at chance in control trials. These results suggest that birds used pre-existing knowledge about the behavior exhibited by differently weighted objects in the wind to infer their weight, using this information to guide their choices.


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Humans and Leaf-Cutter Ants Contribute to Global Warming through Carbon Dioxide Emissions 

Humans and Leaf-Cutter Ants Contribute to Global Warming through Carbon Dioxide Emissions  | Física Interessante | Scoop.it

Humans are not the only animals to build elaborate housing and grow crops—or to add carbon dioxide (CO2) to the atmosphere through their industry. A new study shows that the leaf-cutter ant Atta cephalotes is also a master builder and cultivator and a significant source of greenhouse gas emissions.

 

Found in ecosystems throughout the New World, Atta species excavate massive, several-meter-deep underground nests that include complex tunnels and chambers, exits, and entrances. The ants drag vast quantities of vegetation into the nests to feed their main food source: a fungus called Leucoagaricus gongylophorus. To maintain the proper concentrations of CO2 and oxygen belowground, the nests also feature air vents and chimney-like turrets that enhance ventilation.

 

Warming soils are releasing ever-increasing amounts of CO2 into the atmosphere, but most climate models don’t account for contributions from animals such as Atta cephalotes, which stir up the soil and release gases at a faster rate. To determine just how much CO2 leaf-cutter ant nests emit, Fernandez-Bou et al. spent more than 2 years monitoring 15 nests in La Selva Biological Station, a rainforest research station in northeast Costa Rica. Each study site included a leaf-cutter ant nest and a similar plot of nestless soil, where the team inserted stainless-steel tubes to collect gas at different depths and measured CO2 emissions from soils and nest openings.

 

They found that the amount of CO2 wafting from the ant nests and the surrounding soils was 15%–60% higher than from nearby nestless soils. Nest openings were the major source of this increase, with emissions up to 100,000 times greater than from control soil plots.


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COSINE-100 Apparently Refutes DAMA's Positive Dark Matter Signal

COSINE-100 Apparently Refutes DAMA's Positive Dark Matter Signal | Física Interessante | Scoop.it

Astrophysical evidence suggests that the universe contains a large amount of non-luminous dark matter, yet no definite signal of it has been observed despite concerted efforts by many experimental groups. One exception to this is the long-debated claim by the DArk MAtter (DAMA) collaboration, which has reported positive observations of dark matter in its sodium-iodide detector array.

 

The new COSINE-100 experiment, based at an underground, dark-matter detector at the Yangyang Underground Laboratory in South Korea, has begun to explore DAMA's claim. It is the first experiment sensitive enough to test DAMA and use the same target material of sodium iodide.

 

COSINE-100 has been recording data since 2016 and now has initial results that challenge the DAMA findings. Those findings are published online this week in the journal Nature." For the first time in 20 years, we have a chance to resolve the DAMA conundrum," said Yale physics professor Reina Maruyama, who is co-spokesperson for COSINE-100 and co-author of the new study.

 

The first phase of COSINE-100's work searches for dark matter by looking for an excess of signal over the expected background in the detector, with the right energy and characteristics. In this initial study, the researchers found no excess of signal in its data, putting DAMA's annual modulation signal at odds with with results from other experiments. COSINE-100 scientists noted that it will take several years of data to fully confirm or refute DAMA's results.

 

The COSINE-100 experiment uses eight low-background, thallium-doped sodium iodide crystals arranged in a 4-by-2 array, giving a total target mass of 106 kg. Each crystal is coupled by two photo sensors to measure the amount of energy deposited in the crystal.

The sodium iodide crystal assemblies are immersed in 2,200 L of light-emitting liquid, which allows for the identification and subsequent reduction of radioactive backgrounds observed by the crystals. The detector is contained within a nested arrangement of copper, lead, and plastic shielding components to reduce the background contribution from external radiation, as well as cosmic ray muons.

 

The COSINE-100 collaboration includes 50 scientists from the U.S., South Korea, the United Kingdom, Brazil, and Indonesia. The Yangyang Underground Laboratory, where the experiment is based, is operated by the Center for Underground Physics of the Institute for Basic Science (IBS) in South Korea.

 

"The initial results carve out a fair portion of the possible dark matter search region drawn by the DAMA signal. In other words, there is little room left for this claim to be from the dark matter interaction unless the dark matter model is significantly modified," said Hyun Su Lee, the other co-spokesperson for COSINE-100, and an associate director of the Center for Underground Physics at IBS.


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A Traversable Wormhole: Newfound Wormhole Allows Information to Escape Black Holes 

A Traversable Wormhole: Newfound Wormhole Allows Information to Escape Black Holes  | Física Interessante | Scoop.it

In 1985, when Carl Sagan was writing the novel Contact, he needed to quickly transport his protagonist Dr. Ellie Arroway from Earth to the star Vega. He had her enter a black hole and exit light-years away, but he didn’t know if this made any sense. The Cornell University astrophysicist and television star consulted his friend Kip Thorne, a black hole expert at the California Institute of Technology (who won a Nobel Prize earlier this month). Thorne knew that Arroway couldn’t get to Vega via a black hole, which is thought to trap and destroy anything that falls in. But it occurred to him that she might make use of another kind of hole consistent with Albert Einstein’s general theory of relativity: a tunnel or “wormhole” connecting distant locations in space-time.

 

While the simplest theoretical wormholes immediately collapse and disappear before anything can get through, Thorne wondered whether it might be possible for an “infinitely advanced” sci-fi civilization to stabilize a wormhole long enough for something or someone to traverse it. He figured out that such a civilization could in fact line the throat of a wormhole with “exotic material” that counteracts its tendency to collapse. The material would possess negative energy, which would deflect radiation and repulse space-time apart from itself. Sagan used the trick in Contact, attributing the invention of the exotic material to an earlier, lost civilization to avoid getting into particulars. Meanwhile, those particulars enthralled Thorne, his students and many other physicists, who spent years exploring traversable wormholes and their theoretical implications. They discovered that these wormholes can serve as time machines, invoking time-travel paradoxes — evidence that exotic material is forbidden in nature. 

 

Now, several decades later, a new species of traversable wormhole has emerged, free of exotic material and full of potential for helping physicists resolve a baffling paradox about black holes. This paradox is the very problem that plagued the early draft of Contact and led Thorne to contemplate traversable wormholes in the first place; namely, that things that fall into black holes seem to vanish without a trace. This total erasure of information breaks the rules of quantum mechanics, and it so puzzles experts that in recent years, some have argued that black hole interiors don’t really exist — that space and time strangely end at their horizons.

 

The flurry of findings started last year with a paper that reported the first traversable wormhole that doesn’t require the insertion of exotic material to stay open. Instead, according to Ping Gao and Daniel Jafferis of Harvard University and Aron Wall of Stanford University, the repulsive negative energy in the wormhole’s throat can be generated from the outside by a special quantum connection between the pair of black holes that form the wormhole’s two mouths. When the black holes are connected in the right way, something tossed into one will shimmy along the wormhole and, following certain events in the outside universe, exit the second. Remarkably, Gao, Jafferis and Wall noticed that their scenario is mathematically equivalent to a process called quantum teleportation, which is key to quantum cryptography and can be demonstrated in laboratory experiments.

 

 

John Preskill, a black hole and quantum gravity expert at Caltech, says the new traversable wormhole comes as a surprise, with implications for the black hole information paradox and black hole interiors. “What I really like,” he said, “is that an observer can enter the black hole and then escape to tell about what she saw.” This suggests that black hole interiors really exist, he explained, and that what goes in must come out.


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Jupiter’s moon Europa may have a belt of 15-meter-tall ice spikes 

Jupiter’s moon Europa may have a belt of 15-meter-tall ice spikes  | Física Interessante | Scoop.it

Landing on Jupiter’s moon Europa will be even harder than we thought due to a forbidding belt of huge ice spikes that could trap or incapacitate a spacecraft.

 

If you want to attempt a landing on Europa, you’d better bring a repair kit. Parts of its surface may be covered in meters-long blades of ice that could make exploring Jupiter’s frigid moon a dangerous endeavor.

 

In the driest, coldest places on Earth, sunlight bouncing off of small depressions in ice and snow creates pointy formations called penitentes, which can reach several meters tall, as shown in the picture above. As the sunlight hits the bottom of the divot it turns the ice directly from a solid to a gas, which floats away and leaves icy spikes behind.

 

Europa is much colder and much drier than Earth because it has almost no atmosphere, and it has lower gravity. Daniel Hobley at Cardiff University, UK, and his colleagues calculated that means it could build even bigger penitentes.

 

The researchers found that, over Europa’s lifetime, they could reach heights of 15 meters, with holes about 7.5 meters across between them. Because penitentes grow faster when the sun is directly overhead, they are likely to mostly appear around the equator. That would give the moon a spiked belt around its middle.

This could be a problem for any spacecraft hoping to land in the region, either because of the spikes or the perfectly spacecraft-sized holes between them.

 

“You can imagine something getting lodged in there and flopping around,” Hobley says. “But if you already know the surface is likely to be spiky and full of holes, you can probably plan around that.”

 

Publication: 

Nature GeoscienceDOI: 10.1038/s41561-018-0235-0


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Physicists finally calculated where the proton’s mass comes from 

Physicists finally calculated where the proton’s mass comes from  | Física Interessante | Scoop.it

New study indicates that the proton is much more than just the sum of its parts.

 

A proton’s mass is more just than the sum of its parts. And now scientists know just what accounts for the subatomic particle’s heft. Protons are made up of even smaller particles called quarks, so you might expect that simply adding up the quarks’ masses should give you the proton’s mass. However, that sum is much too small to explain the proton’s bulk. And new, detailed calculations show that only 9 percent of the proton’s heft comes from the mass of constituent quarks. The rest of the proton’s mass comes from complicated effects occurring inside the particle, researchers report in the Nov. 23 Physical Review Letters.

 

Quarks get their masses from a process connected to the Higgs boson, an elementary particle first detected in 2012 (SN: 7/28/12, p. 5). But “the quark masses are tiny,” says study coauthor and theoretical physicist Keh-Fei Liu of the University of Kentucky in Lexington. So, for protons, the Higgs explanation falls short.

Instead, most of the proton’s 938 million electron volts of mass is due to complexities of quantum chromodynamics, or QCD, the theory which accounts for the churning of particles within the proton. Making calculations with QCD is extremely difficult, so to study the proton’s properties theoretically, scientists rely on a technique called lattice QCD, in which space and time are broken up into a grid, upon which the quarks reside.

 

Using this technique, physicists had previously calculated the proton’s mass (SN: 12/20/08, p. 13). But scientists hadn’t divvied up where that mass comes from until now, says theoretical physicist André Walker-Loud of Lawrence Berkeley National Laboratory in California. “It’s exciting because it’s a sign that … we’ve really hit this new era” in which lattice QCD can be used to better understand nuclear physics.

 

In addition to the 9 percent of the proton’s mass that comes from quarks’ heft, 32 percent comes from the energy of the quarks zipping around inside the proton, Liu and colleagues found. (That’s because energy and mass are two sides of the same coin, thanks to Einstein’s famous equation, E=mc2.) Other occupants of the proton, massless particles called gluons that help hold quarks together, contribute another 36 percent via their energy.

 

The remaining 23 percent arises due to quantum effects that occur when quarks and gluons interact in complicated ways within the proton. Those interactions cause QCD to flout a principle called scale invariance. In scale invariant theories, stretching or shrinking space and time makes no difference to the theories’ results. Massive particles provide the theory with a scale, so when QCD defies scale invariance, protons also gain mass.

 

The results of the study aren’t surprising, says theoretical physicist Andreas Kronfeld of Fermilab in Batavia, Ill. Scientists have long suspected that the proton’s mass was made up in this way. But, he says, “this kind of calculation replaces a belief with scientific knowledge.”


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The approach to predictive medicine that is taking genomics research by storm 

The approach to predictive medicine that is taking genomics research by storm  | Física Interessante | Scoop.it

Polygenic risk scores represent a giant leap for gene-based diagnostic tests. Here is what they mean for predictive personalized medicine:

 

When researchers completed the first drafts of the human genome in the early 2000s, many expected that it would mark the start of a medical revolution. Geneticists started searching for the differences that might explain why one person develops diabetes or heart disease whereas another does not. The idea was simple: compare a group of people with the condition to a group without and look for differences in their DNA. The variations generally came in the form of DNA-letter swaps, known as single nucleotide polymorphisms, or SNPs. If people with a condition tended to have a T at a certain location whereas others had a C, that suggested that the SNP was associated in some way with the disease.

 

These genome-wide association studies — or GWASs, as they came to be known — became very popular. But after years of searching, scientists could still only explain a small bit of the inherited risk for common diseases. It turned out that most of these conditions were related to many more SNPs than scientists had first expected, says Ali Torkamani, a geneticist at the Scripps Research Institute, La Jolla, California.

 

Worse still, a majority of the variants conferred a very small risk — detectable only when surveying huge groups of people.“We didn’t have the sample size to really drive prediction as well as some people naively thought,” says Ewan Birney, director of the European Bioinformatics Institute in Hinxton, UK. By 2007, geneticists were fretting about something they called “missing heritability”. It was clear that many of these conditions had a genetic component, but GWASs clearly weren’t catching much of it.

 

Today, things are finally changing. With access to massive data sets, as well as advances in how data are analyzed, scientists are getting better at measuring those very small risks. A prime example is the technique geneticist Kathiresan used to generate his 6.6-million SNP score, which was published in August 20181. He and his team took data from a 2015 meta-analysis that combined 48 GWASs, consisting of 61,000 people with coronary artery disease and 120,000 controls2. They then tested their polygenic predictor on 290,000 people in the UK Biobank, finding that those scoring in the highest few percentiles had on average several times higher risk of developing the disease than did the rest of the population. Of the 23,000 people who received the highest scores, for example, 7% had coronary artery disease, compared with 2.7% of the remaining population. The group conducted similar analyses for four other disorders, including inflammatory bowel disease and breast cancer, each time identifying a group who scored in the top few percentiles and were at particularly high risk.

 

Understanding how people will react to polygenic scores is a high priority for researchers. Ripatti and his colleagues have given more than 7,000 individuals in Finland information about their likelihood of developing heart disease, based on both polygenic scores and conventional risk factors such as high blood pressure. Most of the respondents say that getting this information motivates them to make positive changes, says Ripatti. Preliminary results suggest that those with high genetic risk are the most likely to take actions such as losing weight or stopping smoking.

 

In nearby Estonia, researchers are in the process of genotyping 100,000 individuals, adding to the 50,000 the country has already sampled. And unlike many other biobanks, participants in the Estonian project can sign up to receive feedback. Among the results being returned to them are polygenic risk scores for type 2 diabetes and cardiovascular disease, says Lili Milani, a geneticist at the Estonian Genome Center at the University of Tartu, Estonia. Similar to the Finnish work, participants are shown graphs of how lifestyle changes could reduce or increase their risk. And, says Milani, initial indications are that people are glad for the advice.

 

For now, people are receiving their scores from genetic counsellors. But Milani is working with the Estonian government to work out how to integrate genomic data into the health-care system, so that it can be used every day by doctors. The country ultimately aims to genotype anyone who’s interested, right up to its entire population of 1.3 million, Milani says. “The goal is to build something so great that all doctors will want to recommend it and all of the population will want it.”

 


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Microplastics discovered in human stools across the globe in a 'first of its kind' study

Microplastics discovered in human stools across the globe in a 'first of its kind' study | Física Interessante | Scoop.it

Researchers monitored a group of participants from 8 countries across the world with results showing that every single stool sample tested positive for the presence of microplastic and up to 9 different plastic types were identified.

Microplastics have been found in the human food chain as particles made of polypropylene (PP), polyethylene-terephthalate (PET) and others were detected in human stools, research presented today at the 26th UEG Week in Vienna reveals.

Microplastics are small particles of plastic less than 5mm and are used in various products for specific purposes; as well as being created unintentionally by the breaking down of larger pieces of plastic through weathering, degradation, wear and tear. Microplastic may impact human health via the GI tract where it could affect the tolerance and immune response of the gut by bioaccumulation or aiding transmission of toxic chemicals and pathogens.

The pilot study was conducted with eight participants from across the globe. Each person kept a food diary in the week leading up to their stool sampling. The diaries showed that all participants were exposed to plastics by consuming plastic wrapped foods or drinking from plastic bottles. None of the participants were vegetarians and six of them consumed sea fish.

The stools were tested at the Environment Agency Austria for 10 types of plastics following a newly developed analytical procedure. Up to nine different plastics, sized between 50 and 500 micrometres, were found, with polypropylene (PP) and polyethylene terephthalate (PET) being the most common. On average, the researchers found 20 microplastic particles per 10g of stool.

Lead researcher Dr. Philipp Schwabl, who is presenting the findings at the 26th UEG Week, commented: "This is the first study of its kind and confirms what we have long suspected, that plastics ultimately reach the human gut. Of particular concern is what this means to us, and especially patients with gastrointestinal diseases. While the highest plastic concentrations in animal studies have been found in the gut, the smallest microplastic particles are capable of entering the blood stream, lymphatic system and may even reach the liver. Now that we have first evidence for microplastics inside humans, we need further research to understand what this means for human health."


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Microplastics discovered in human stools across the globe in a 'first of its kind' study

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The story of moonshine symmetry, number theory, and the monster

The story of moonshine symmetry, number theory, and the monster | Física Interessante | Scoop.it

In 1978, the mathematician John McKay noticed what seemed like an odd coincidence. He had been studying the different ways of representing the structure of a mysterious entity called the monster group, a gargantuan algebraic object that, mathematicians believed, captured a new kind of symmetry. Mathematicians weren’t sure that the monster group actually existed, but they knew that if it did exist, it acted in special ways in particular dimensions, the first two of which were 1 and 196,883.

 

McKay, of Concordia University in Montreal, happened to pick up a mathematics paper in a completely different field, involving something called the j-function, one of the most fundamental objects in number theory. Strangely enough, this function’s first important coefficient is 196,884, which McKay instantly recognized as the sum of the monster’s first two special dimensions.

 

Most mathematicians dismissed the finding as a fluke, since there was no reason to expect the monster and the j-function to be even remotely related. However, the connection caught the attention of John Thompson, a Fields medalist now at the University of Florida in Gainesville, who made an additional discovery. The j-function’s second coefficient, 21,493,760, is the sum of the first three special dimensions of the monster: 1 + 196,883 + 21,296,876. It seemed as if the j-function was somehow controlling the structure of the elusive monster group.


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Water-worlds are very common on Earth-size exoplanets – some may even contain vast amounts of water 

Water-worlds are very common on Earth-size exoplanets – some may even contain vast amounts of water  | Física Interessante | Scoop.it
Scientists have shown that water is likely to be a major component of those exoplanets (planets orbiting other stars) which are between two to four times the size of Earth. It will have implications for the search of life in our Galaxy.

 

Scientists have shown that water is likely to be a major component of those exoplanets (planets orbiting other stars) which are between two to four times the size of Earth. It will have implications for the search of life in our Galaxy. The work is presented at the Goldschmidt conference in Boston.

 

The 1992 discovery of exoplanets orbiting other stars has sparked interest in understanding the composition of these planets to determine, among other goals, whether they are suitable for the development of life. Now a new evaluation of data from the exoplanet-hunting Kepler Space Telescope and the Gaia mission indicates that many of the known planets may contain as much as 50% water. This is much more than the Earth's 0.02% (by weight) water content.

 

"It was a huge surprise to realize that there must be so many water-worlds," said lead researcher Dr Li Zeng (Harvard University),

Scientists have found that many of the 4000 confirmed or candidate exoplanets discovered so far fall into two size categories: those with the planetary radius averaging around 1.5 that of the Earth, and those averaging around 2.5 times the radius of the Earth.

 

Now a group of International scientists, after analyzing the exoplanets with mass measurements and recent radius measurements from the Gaia satellite, have developed a model of their internal structure. "We have looked at how mass relates to radius, and developed a model which might explain the relationship," said Li Zeng. The model indicates that those exoplanets which have a radius of around x 1.5 Earth radius tend to be rocky planets (of typically x5 the mass of the Earth), while those with a radius of x2.5 Earth radius (with a mass around x10 that of the Earth) are probably water worlds."

 

"This is water, but not as commonly found here on Earth," said Li Zeng. "Their surface temperature is expected to be in the 200 to 500 degree Celsius range. Their surface may be shrouded in a water-vapor-dominated atmosphere, with a liquid water layer underneath. Moving deeper, one would expect to find this water transforms into high-pressure ices before we reaching the solid rocky core. The beauty of the model is that it explains just how composition relates to the known facts about these planets."

 

Li Zeng continued, "Our data indicate that about 35% of all known exoplanets which are bigger than Earth should be water-rich. These water worlds likely formed in similar ways to the giant planet cores (Jupiter, Saturn, Uranus, Neptune) which we find in our own solar system. The newly-launched TESS mission will find many more of them, with the help of ground-based spectroscopic follow-up. The next generation space telescope, the James Webb Space Telescope, will hopefully characterize the atmosphere of some of them. This is an exciting time for those interested in these remote worlds."

 

Professor Sara Seager, Professor of Planetary Science at Massachusetts Institute of Technology, and deputy science director of the recently-launched TESS (Transiting Exoplanet Survey Satellite) mission, which will search for exoplanets, said:

"It's amazing to think that the enigmatic intermediate-size exoplanets could be water worlds with vast amounts of water. Hopefully atmosphere observations in the future -- of thick steam atmospheres -- can support or refute the new findings."


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Ness Crouch's curator insight, August 25, 2018 5:37 PM
This is an interesting field to discuss for children, as they are growing up a world where it is normal that planets exist around other stars. 
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Fake news enters a whole new level: This Face2Face software can make any person on video appear to say anything a source actor wants them to say. 

You know how they say, "Show me pictures or video, or it didn't happen"? Well, the days when you could trust what you see on video in real time are officially coming to an end thanks to a new kind of face tracking.

 

A team from Stanford, the Max Planck Institute for Informatics and the University of Erlangen-Nuremberg has produced a video demonstrating how its software, called Face2Face, in combination with a common webcam, can make any person on video appear to say anything a source actor wants them to say.

 

In addition to perfectly capturing the real-time talking motions of the actor and placing them seamlessly on the video subject, the software also accounts for real-time facial expressions, including distinct movements such as eyebrow raises.

 

To show off the system, the team used YouTube videos of U.S. President George W. Bush, Russian President Vladimir Putin and Republican presidential candidate Donald Trump. In each case, the facial masking is flawless, effectively turning the video subject into the actor's puppet.

 

It might be fun to mix this up with something like "Say it with Trump," but for now the software is still in the research phase. "Unfortunately, the software is currently not publicly available — it's just a research project," team member Matthias Niessner told Mashable. "However, we are thinking about commercializing it given that we are getting so many requests." We knew this kind of stuff was possible in the special effects editing room, but the ability to do it in real time — without those nagging "uncanny valley" artifacts — could change how we interpret video documentation forever.


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What Data Scientists Really Do, According to 35 Data Scientists 

What Data Scientists Really Do, According to 35 Data Scientists  | Física Interessante | Scoop.it
Many of my guests are skeptical not only of the fetishization of artificial general intelligence by the mainstream media (including headlines such as VentureBeat’s “An AI god will emerge by 2042 and write its own bible. Will you worship it?”), but also of the buzz around machine learning and deep learning

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