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The Eternal Itch: Dante's Eighth Circle of Hell

Onchocerciasis or River Blindness is caused by a parasite endemic to Africa that is transferred to a person by the bite of a blackfly. The parasite matures in the host within a year, and then reproduces up to a thousand tiny worms per day.

When untreated, those microfilarial worms invade the skin and travel throughout the body. That results in extreme, extensive, and persistent itching, along with subcutaneous bumps and eventual blindness after they burrow into the eyes.

The parasite has infected up to 25 million people (almost all in Africa), and suicide due to the debilitating itch is unfortunately not uncommon.

There are many reports of people in Africa who never get relief despite deep and intense scratching. In the worst cases, individuals have resorted to heating machetes over a fire and using the hot blades to "numb" or skin their backs out of desperation. Some have used broken shards of ceramic pots to try to gouge the worms out to no avail, and others have dumped boiling hot water on themselves in an attempt to feel "better" -- anything to make the itching stop.

Two of this year's Nobel Prize winners in Medicine, Drs. Omura (Japan) and Campbell (USA) were recognized for their discovery of a drug used to treat River Blindness. More:

Source: +Johnathan Chung responds to a question in the +Science on Google+ community. The best comments or answers to questions will be posted as part of our  #Askascientist  series. Do you have science questions for us? Use the Science Outreach category to ask the science community. 
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You've probably seen the Mandelbrot set before, but you may never have seen how it evolves from one iteration to the next.
Today in Mathematics History: Happy Birthday, Benoit Mandelbrot

Benoit B. Mandelbrot  (20 November 1924 – 14 October 2010) was a Polish-born, French and American scientist-mathematician. He has been most widely recognized and honored for his discoveries in the field of fractal geometry.

Science writer Arthur C. Clarke credits fractals as being "one of the most astonishing discoveries in the entire history of mathematics".

Studying complex dynamics in the 1970s, Benoit Mandelbrot had a key insight about a particular set of mathematical objects: that these self-similar structures with infinitely repeating complexities were not just curiosities, as they'd been considered since the turn of the century, but were in fact a key to explaining non-smooth objects and complex data sets -- which make up, let's face it, quite a lot of the world. Mandelbrot coined the term "fractal" to describe these objects, and set about sharing his insight with the world.

The Mandelbrot set (expressed as z² + c) was named in Mandelbrot's honor by Adrien Douady and John H. Hubbard. Its boundary can be magnified infinitely and yet remain magnificently complicated, and its elegant shape made it a poster child for the popular understanding of fractals. Led by Mandelbrot's enthusiastic work, fractal math has brought new insight to the study of pretty much everything, from the behavior of stocks to the distribution of stars in the universe.

Read more>>

Animation explanation: this beautiful Mandelbrot Set has been developed in R Programming Language.
Read more at source>>

Further reading

Mandelbrot biography in Mac Tutor archive>>

For Italian speakers a my article about fractal geometry>>

#history_of_mathematics #benoit_mandelbrot #fractals
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The Elephant Alarm for Humans : African elephants have a signal for humans. And it spells trouble. Studies show that elephants react quickly to human voices, becoming more vigilant and running away from the source of human sounds. But we already knew Elephants had a vocabulary. ....

Study shows how elephants react : Researchers from Oxford University carried out a series of audio experiments in which recordings of the voices of the Samburu, a local tribe from North Kenya, were played to resting elephants. The elephants quickly reacted, becoming more vigilant and running away from the sound whilst emitting a distinctive low rumble. When the team, having recorded this rumble, played it back to a group of elephants they reacted in a similar way to the sound of the Samburu voices; running away and becoming very vigilant, perhaps searching for the potentially lethal threat of human hunters.

Is it language? : Lucy explains: 'Interestingly, the acoustic analysis done by Joseph Soltis at his Disney laboratory showed that the difference between the ''bee alarm rumble'' and the ''human alarm rumble'' is the same as a vowel-change in human language, which can change the meaning of words (think of ''boo'' and ''bee''). Elephants use similar vowel-like changes in their rumbles to differentiate the type of threat they experience, and so give specific warnings to other elephants who can decipher the sounds.'

References and Sources


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The Incredible Shrinking Atom: The trick is to take the electron in a hydrogen atom and replace it with a muon.  This is a particle 207 times heavier than an electron, but otherwise very similar.  Unfortunately a muon has a half-life of just 2 microseconds: then it decays into an electron and some other crud.  
Miniature atoms

In The Incredible Shrinking Man, a guy exposed to radiation becomes smaller and smaller.   Eventually he realizes he'll shrink forever - even down to subatomic size.  Of course that's impossible.  But guess what: we can now make miniature atoms!

In fact we can make atoms almost like hydrogen, but 1/186 times as big across.  Unfortunately they only last 2 microseconds.  But that's still long enough for them to form molecules, and for us to do chemical experiments with them.  Chemists have gotten really good at this stuff.

The trick is to take the electron in a hydrogen atom and replace it with a muon.  This is a particle 207 times heavier than an electron, but otherwise very similar.  Unfortunately a muon has a half-life of just 2 microseconds: then it decays into an electron and some other crud.  

Why is an ordinary hydrogen atom the size it is, anyway?  It's the uncertainty principle.  The atom is making its energy as small as possible while remaining consistent with the uncertainty principle.  

A hydrogen atom is made of an electron and a proton.  If it were bigger, its potential energy would increase, because the electron would be further from the proton.  So, the atom "wants to be small".  And without quantum mechanics to save it, it would collapse down to a point: The Incredible Shrinking Atom.

But if the atom were smaller, you'd know the position of its particles more precisely - so the uncertainty principle says you'd know their momentum less precisely.  They'd be wiggling around more wildly and unpredictably  So the kinetic energy would, on average, be higher.  

So there's a tradeoff!  Too big means lots of potential energy.  Too small means lots of kinetic energy.  Somewhere in the middle is the best - and you can use this to actually calculate how big a hydrogen atom is!   

But what if you could change the mass of the electron?  This would change the calculation.  It turns out that making electrons heavier would make atoms smaller!  

While we can't make electrons heavier, we can do the next best thing: use muons.

Muonic hydrogen is a muon orbiting a proton.  It's like an atom, but much smaller than usual, so it does weirdly different things when it meets an ordinary atom.  It's a whole new exotic playground for chemists.  

And, you can do nuclear fusion more easily if you start with smaller atoms!  It's called muon-catalyzed fusion, and people have really done it.  The only problem is that it takes a whole lot of energy to make muons, and they don't last long.  So, it's not practical - it doesn't pay off.  At least not yet.  Maybe we just need a few more brilliant ideas:

By the way: a while ago I talked about making a version of hydrogen where we keep the electron and replace the proton by a positively charged antimuon.  That's called muonium.  Muonium is lighter than ordinary hydrogen but almost the same size, just a tiny bit bigger.  It's chemically almost the same as hydrogen, except that it decays in 2 microseconds.  

With muonic hydrogen it's the reverse: it's a lot smaller, but it's just a bit heavier.  It's chemically very different from ordinary hydrogen.

Finally, for the übernerds:

If you do the calculation, you can show that the radius of a hydrogen-like atom is proportional to


where m is the mass of the lighter particle and M is the mass of the heavier one.  If we say an electron has mass 1, then a muon has mass 207 and a proton has mass 1836.  You can use this formula to see that muonic hydrogen has a radius 1/186 as big as ordinary hydrogen, while muonium has a radius 1.004 times as big.  
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Order is essential in the definition of multiplication because not all forms of multiplication are commutative, such as matrix multiplication. This is why it is taught as a separate property.
Why Was 5 x 3 = 5 + 5 + 5 Marked Wrong?

It seems absurd at first glance: we all know that 5 x 3 is equal to 3 x 5, which is 15. But check out the formal definition of multiplication:

The multiplication of two whole numbers, when thinking of multiplication as repeated addition, is equivalent to adding as many copies of one of them (multiplicand, written second) as the value of the other one (multiplier, written first).

In other words, 5 x 3 = 3 + 3 + 3 + 3 + 3

Why should this matter? It matters because the term equal is not the same as equivalent. Although 5 x 3 is equal to 5 + 5 + 5 it is not equivalent to 3 + 3 + 3 + 3 + 3. Suppose you were buying chocolates for your sweethearts on Valentine's Day. You would have 3 boxes of 5 chocolates each in one case, and 5 boxes of 3 chocolates in the other case. What you choose to buy depends on how many sweethearts you are trying to impress, right? 

Perhaps more importantly, the difference is also a fundamental concept in computer science. 

Notice that the second problem is marked incorrect as well. That's because keeping rows and columns straight in matrix multiplication is important. As explained in the link below: "Order is essential in the definition of multiplication because not all forms of multiplication are commutative, such as matrix multiplication. This is why it is taught as a separate property."

So, what do you think? Do you agree with the teacher or not?
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By the way, I made a similar error when I was seventeen. I've lived with a ruined left arm and loss of sight in my left eye now for fifty-eight years. Originality and innovation are very important, but mathematics must, by nature be exact!
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The center of a black hole is not so much a place as  a moment in time. It is literally as inescapable as tomorrow.
Falling into a black hole with a flashlight.

It's a common misconception that, because an observer falling into a black hole appears to stop, time stops for that observer. That's not really true.

Think of it this way. The event horizon is the point where light cannot escape the black hole, right? Well, suppose I jump into a black hole carrying a flashlight and you watch. As I get closer to the event horizon, the light rays from my flash light will have a harder and harder time getting away from the black hole to your eyes.

Eventually, they won't be able to get to your eyes at all... after I pass the event horizon. But, the instant before I fall in, the light rays will take a huge, but finite time to reach you. 

The effect is that, for the age of the universe, you will see the light rays I emitted just before I passed the event horizon. And I will appear to have stopped.

Past the event horizon

Although to outside observers, I appear to have stopped. I may not actually notice anything strange as I pass the event horizon (depending on the size of the black hole). I will eventually be torn apart by tidal forces, but for a large black hole, these are weak near the event horizon.

From my perspective, I'm just travelling through space, and I experience time somewhat normally. This is the difference between proper time and coordinate time. Proper time is the time experience by a person. Coordinate time is just a label.

However, one strange thing will happen to me inside the black hole... and that is that the singularity, the center of the black hole, is irrevocably in my future. The center of a black hole is not so much a place as  a moment in time. It is literally as inescapable as tomorrow.

This post was inspired by a question on the +Science on Google+ community by +Dustin Thurston . Original post here:

Image is a simulation of gravitational of the milky way by a black hole. (Said black hole does not exist.) The creator, Ute Krauss, has a 
lot of great relativity visualizations. You can find them here:

Source: The description I just gave can be found in most general relativity textbooks. For a free treatment, I recommend Sean Carroll's lecture notes, published online:

#physics   #astrophysics   #science  
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OOH looks gross
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Have them in circles
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How fast is the universe expanding?

A galaxy cluster one megaparsec away from us is probably moving away from us at about 70 km/s. That's Hubble's law:'s_law

The basic idea is that new empty space is being created at a (roughly) constant rate throughout the universe. Therefore, the further away an object is from us, the more empty space is being created between it and us, because there's more space. And so it appears to be moving faster.

That means stuff forty-five billion lightyears from us appears to be moving away from us at the speed of light. But that's an illusion. It's not really moving.

Think about somebody baking raisin bread in the oven. As the bread bakes, it expands. The raisins don't move, but they appear to get further away from each other.

That's why it can look like things are going away from us faster than light, when they're really not.

(The rate of creation of empty space used to be considered constant, but we believe it's changing. We don't know what's causing that change.,... but we've given it the name dark energy.

If you want a more complete description, including some about the history of Hubble and his law, you could read this article I wrote a while back.

Source: +Jonah Miller  responds to a question in the +Science on Google+ community. The best answers to questions will be posted as part of our  #Askascientist  series. Do you have science questions for us? Use the Science Outreach category to ask the science community. 

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+Alan Kerlin that's right, massless particles all always go the speed of light.
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We've all read the headlines about the link between processed meat link and cancer. But what exactly is the risk, and should we give up bacon and burgers? Is it really as bad as smoking? What is the underlying mechanism behind the increased risk of developing cancer? Join us for a +Science on Google+ and +Cancer Research UK  Hangout on Air as we speak to Dr Kathryn Bradbury and Professor Owen Sansom about this story. 

Kathryn is a nutritional epidemiologist at the University of Oxford who studies the links between diet and cancer. Owen is a molecular biologist at the Cancer Research UK Beatson Institute in Glasgow, who is investigating the cell signalling pathways that are activated in colon cancer. 

This HOA will be hosted by Dr +Buddhini Samarasinghe and Dr +Kat Arney  . You can tune in on Friday November 27th at 4 PM UK time. The hangout will also be available for viewing on our YouTube channel ( after the event.
This Hangout On Air is hosted by Science on Google+. The live video broadcast will begin soon.
Processed Meat and Cancer: What is the risk?
Tomorrow, November 27, 11:00 AM
Hangouts On Air - Broadcast for free

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Sorry can't attend, but, I will watch! +Cheryl Ann MacDonald 
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Human intelligence, then, cannot be traced to a single organ, no matter how large; it emerged from a serendipitous confluence of adaptations throughout the body. Despite our ongoing obsession with the size of our noggins, the fact is that our intelligence has always been so much bigger than our brain.
Quanta Discusses Recent Brain Research

Many of you already read Quanta but this is another excellent article that I thought deserved a summary share, How Humans Evolved Supersized Brains. The article delves into the ongoing puzzle as to why and how human brains came to be so big and powerful; why over less than 3 million years they quadrupled in size from 350g to 1,300g, when primates took 60 million years to reach 350g brains in the first place. 

Some points of interest:

➤ New techniques to dissolve brains and extract and count cell nuclei give much more accurate cell counts for brains and, for example, show that larger brains do not always have more neurons and neuronal distribution is often different. The human brain has more neurons in the cerebral cortex than any other animal. 

➤ While an elephant has a brain 2.5 times as large as a human (2.8kg vs 1.2kg), the cerebral cortex of the human brain has 3 times as many neurons (16.3 billion vs 5.6 billion). This is the first time I’ve come across this fact. 

➤ While the human brain as about 86 billion neurons, 69 billion are in the cerebellum and only 16 billion are in the cerebral cortex for high-order intelligence and reasoning. To me this suggests a sort of computational overhang with regard to developing neuromorphic AI: you won’t need hardware that can replicate 86 billion neurons, but only 20% of that - so ~2.5 doublings or ~5 years earlier than expected. 

➤ Human brain makes up 2% of body mass but consumes 20% of total energy, whereas a chimpanzee requires only half that. 
Analysis of cellular glucose-importing genes in the brain and muscle reveals that such genes are 3.2 times more active in human brains compared to chimp brains, but 1.6 times more active in chimp muscles compared to human muscles, and identically active in the respective livers. Human regulatory sequences for these genes show signs of accelerated evolution. Accounting for size and weight, chimp muscles are about twice as strong as humans. 

➤ Key regulatory sequences active in brain development were taken from humans and chimps and introduced into mice: mice with the human version developed brains 12% larger and had cells that divide and multiply in 9 hours instead of 12. 

Goldilocks Factors for Human Intelligence

The development of human intelligence appears dependent on a fortuitous confluence of many different factors:

➤ Development of bipedalism to free up hands for tool-making, at the expense of slower movement compared to predators. 

➤ Development fire-building and hunting to source easier-to-digest and higher-quality foods due to energy allocation away from gut and muscles.

➤ Development of extreme manual dexterity. 

➤ Development of vocal tract capable of complex communication at the expense of choking hazards. 

➤ Development of extremely dense and dangerously energy hungry neural cortex at the expense of muscle power.  

➤ Development of extreme sociality to facilitate large, stable groups of individuals, requiring a long childhood and retention of play and curiosity with age, at the expense of more than a decade of youthful defenselessness. 

➤ I think the general process of neoteny, the retention of juvenile characteristics into adulthood is important here in general to facilitate a great many of these factors. 

➤ A complex environment nonetheless conducive to the survival of such a physically weak animal is also important. 

When considering the development of intelligence not only on Earth, but also elsewhere in the Universe, these are all important factors that should feed into and influence the Drake Equation and Fermi Paradox. There are a lot of subtle factors that were required to be present in just the right way at just the right time for human intelligence to begin to emerge and develop; a lot of luck seems to have been involved. Primate brains were quite content to remain at 350g for 60 million years, not to mention the dinosaur brains before them that were content to remain smaller for a much longer period of time. I hope as we learn more about these different factors we gain a clearer idea of how astronomically improbable the development of our intelligence was and so a greater degree of confidence that the Great Filter is behind us. 

Main article here: 

#brain   #intelligence   #evolution
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The authors talk about the increased availability of opioid painkillers, and the increased use of heroin within this group, as a possible contributing factor, but it seems hard to ignore the ties between this rise and the collapse of the prospective economic futures of people in this group.
You may have seen this story circulating around the press: non-Hispanic whites in the US, aged 45-54, are dying at an alarming rate. I'm sad to say that, after going through the original research fairly carefully, they appear to have done a good job – the results are real, and telling.

First of all, a link: The research itself is available online at . It's a very readable paper, and if you're comfortable with the scientific literature, I encourage you to read it. The Washington Post article (linked below) is probably the best general-public summary so far.

Second, let me summarize what the research did and found. They looked at records of mortality and morbidity (M&M for short; morbidity in this case means medical conditions which significantly affect one's ability to function in daily life) from the Centers for Disease Control (CDC), which study these things carefully, and dug into the statistics. What they found is that for all groups in the developed world, M&M has been steadily decreasing – with one notable exception.

Note that this doesn't mean that all groups have good M&M rates: for example, the rate for black, non-Hispanic adults in the US is much worse than the rate for white, non-Hispanic adults, but that rate in 2013 is much better (almost 50% better!) than it was in 1998. Improvements have been happening across the board.

The one marked exception was white, non-Hispanic adults with less than a Bachelor's degree. For this group, three particular sources of death have been surging since 1998: suicide, drug and alcohol poisoning, and chronic liver disease and cirrhosis. This surge has affected all age groups, and appears to affect men and women equally; but it affects people with less than a high school diploma the most, people with a high school diploma or some college significantly, and people with a college degree or more very little.

For people aged 45-54 in particular, this surge has been so high as to completely counter all other improvements in mortality. The graph below shows the annual death rate for various groups for that age range.

The scale of this effect is tremendous, corresponding to roughly half a million excess deaths during this 15-year period. That's on the same scale as the US death toll from the AIDS epidemic, which claimed 650,000 lives from 1981 to 2015. And like with epidemic diseases, for every one person who dies, many more are sickened and their lives are impaired.

And given what appears to be a very rigorous analysis of the data, I think we have to accept that this result is real. 

The authors talk about the increased availability of opioid painkillers, and the increased use of heroin within this group, as a possible contributing factor, but it seems hard to ignore the ties between this rise and the collapse of the prospective economic futures of people in this group.

If I had to look at this for unexpected patterns besides the blindingly obvious, a few things strike me:

* Its limitation to the non-Hispanic white population is interesting, because most things that go horribly wrong will also hit the black and Hispanic population as well. The one notable exception is when things are already bad for those populations and don't get any worse.

Interestingly, that exception appears to apply to the recent economic downturn. I recently wrote a post about the effects of redlining and economic policy on people's wealth (, and one of the interesting things which showed up in the main data graph which drove that post (which that particular article didn't spend too much time on) was how the Great Recession of 2007 had a huge effect on the net wealth of the white population, but very little on the Hispanic and black population. In no small part, that's because the economic policies of previous decades left those populations with so little wealth (and so little housing wealth, in particular) that they had little left to lose in that recession. 

In fact, this sort of effect would synchronize well with the results of this new paper, since non-Hispanic white Americans with less than a college degree were (by all metrics) the ones most affected by the recent economic troubles: entire job sectors which this group dominated prior to this period, such as manufacturing, have essentially crashed and seem unlikely ever to recover, at least to the extent of providing quasi-middle-class existences to anyone.

* The gender balance of the effect was somewhat surprising to me. I would have guessed that a process like this would affect men more than women, as they are more likely to occupy the position of "breadwinner." However, the effects of an economic crash will hit all of a family, and the male/female breadwinner ratio has been declining for decades, so apparently this is not a statistically significant difference.

* The extreme specificity of the causes of death which triggered this rise surprised me. I would expect that any rise in causes of death would be fairly broad, if nothing else because of the fraction of suicides misclassified as accidents or other causes of death. Apparently, this was not the case.

* Poisoning – that is, accidental or "intent undetermined" deaths from overdoses of alcohol, prescription, and illegal drugs – has surpassed lung cancer as a cause of death in this 45-54 group, and suicide is likely to do so within the next two or three years.

* Other things that you may expect to correlate with this shift in death rates, such as obesity, don't. While people with a BMI over 30 have higher rates of all of the various morbidity and mortality types, they have seen the same rates of change as the greater population, and the change in rates of obesity itself contributed only a small amount to total health rate changes.

* Other countries in this study had similar economic problems, but none of them showed the same shift in M&M rates. The paper notes that these countries use different methods for retirement: defined-benefit pension plans, as opposed to the US, which has shifted largely to defined-contribution plans, which are much more vulnerable to stock market risk. While I think there isn't enough data to strongly link these two (there are, after all, quite a few other differences between the countries), the reasons for these differences definitely bear further investigation.

So I don't have any strong public policy recommendations here, except one: there is a real, severe, and lethal public health crisis spreading over the country, and we need to treat it as one. Further study is definitely needed to identify not simply the root cause, but the factors which make this so much more lethal for one group than for others. And we need to be ready to act seriously in order to stanch the bleeding.
Drugs, alcohol and suicide appear to be taking a toll on men and women ages 45-54 with no college education.
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+David Carlson Africa needs you .
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What would happen if you dropped a billion grains of sand on top of each other and let them cascade into a stable pattern following a simple mathematical rule? Find out more below. (The answer is in the picture.)
The sandpile model with a billion grains of sand

This picture by Wesley Pegden shows an example of a stable configuration in the abelian sandpile model on a square lattice. This consists of a rectangular square array of a large number of pixels. Each pixel has one of four possible colours (blue, cyan, yellow and maroon) corresponding to the numbers 0, 1, 2 and 3 respectively. These numbers should be thought of as representing stacks of tokens, often called chips, which in this case might be grains of sand.

Despite its intricate fractal structure, this picture is generated by a simple iterative process, as follows. If a vertex of the grid (i.e., one of pixels) holds at least 4 chips, it is allowed to fire, meaning that it transfers one chip to each of its neighbours to the north, south, east and west. The boundary of the grid can be thought of as the edge of a cliff, meaning that any chips that cross the boundary will fall off and be lost. If no vertices can fire in a particular chip configuration, then the configuration is called stable. For example, the configuration in the picture is stable, because no pixel holds 4 or more chips.

One of the key theorems about this particular sandpile model is that any chip configuration will become stable after firing various vertices a finite number of times. More surprisingly, the ultimate stable configuration obtained does not depend on the order in which the vertices were fired. The irrelevance of the order in which the vertices are fired is why the model is called “abelian”.

If we start with 2^{30} chips, all placed on the same pixel, and we then perform firings repeatedly until a stable configuration is reached, the resulting stable configuration is the one shown in the picture. (The number 2^{30} is just over a billion.) It is clear from the symmetrical nature of the firing rules that the resulting picture will be symmetric under rotation by a right angle or mirror-reflection, but the fractal-like structures are much more surprising.

Relevant links

Wesley Pegden is an Assistant Professor of Mathematics at Carnegie Mellon University. His home page includes an interactive zoomable version of this image:
The page also allows you to generate corresponding images on other lattices, including a triangular lattice with six colours, and a hexagonal lattice with three colours. You can also change the number of chips, like Dr Evil from Austin Powers. (One billion chips. No, one million chips.)

The article The Amazing, Autotuning Sandpile by Jordan Ellenberg appeared in Nautilus in April 2015:
The article discusses this picture, and also includes some details from it, including a close-up of the centre.

I have posted about the sandpile model before, here:
The other post includes more technical details, and describes how to construct a group out of certain sandpiles. A surprising feature of this is that the identity element of the group has a very complicated appearance.

David Perkinson is a Professor of Mathematics at Reed College. He has a gallery of images relating to abelian sandpiles:

(Found via Cliff Pickover (@pickover) on Twitter.)

#mathematics #scienceeveryday
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Finally, as noted in the press release (see the first link in this post), the researchers have not patented their technology as they want to make it freely available to everyone who needs access to the improved varieties of cassava.
Engineering Cassava to Combat Vitamin B6 Deficiency

Press release: (free)

Original research note: (paywall)

Vitamin B6 is an essential nutrient for humans. It is required for numerous biochemical processes in the human body, and deficiency in this vitamin is associated with numerous pathological conditions, including cardiovascular disease, diabetes, various neurological diseases, and nodding syndrome (NS), which is a childhood condition found rather commonly in eastern Africa in areas where vitamin B6 deficiency is endemic. (1,2)

A recent publication in Nature Biotechnology by a multinational group of scientists has found a possible way to solve vitamin B6 deficiency through genetic engineering of cassava. Cassava, also called Brazilian arrowroot, manioc, tapioca, and yuca (not the same as the unrelated plant known as yucca) is a New World plant that has become an important dietary staple throughout the tropical and subtropical world (3). Cassava is as important to African farmers as rice is to Asian farmers or as wheat and potatoes are to European farmers (4, citing a personal communication). Various researchers have suggested for some time that genetic engineering of cassava could be used to ameliorate malnutrition and dietary deficiencies (2, 4-7). The paper in Nature Biotechnology reports the successful engineering of cassava to produce vitamin B6 (1).

The enzymes PDX1 and PDX2 are needed to synthesize vitamin B6 in plants. Genes encoding PDX1 and PDX2 were taken from the plant Arabidopsis thaliana (8) and modified to put them under control of one of two promoters. One promoter (CaMV35S) allowed PDX1 and PDX2 to be expressed throughout the entire cassava plant, while the other promoter (Patatin) enhanced expression of the two genes in the cassava roots. Engineered cassava plants from each group, named 35S and PAT (based on the promoter that was used), were then grown from tissue culture in a greenhouse. Evaluation of the resulting plants showed no significant morphological differences but did show a large increase for vitamin B6 expressed in the plants' leaves and roots (35S) or in the roots (PAT). The amount of vitamin B6 expressed in the transgenic leaves was increased from 3.9-fold to 48.2-fold over wild-type cassava, while the amount of vitamin B6 expressed in transgenic roots increased 1.9- to 5.8-fold over wild type cassava. Evaluation in a test field in Shanghai, China, showed that the genetically engineered plants were stable when grown in wild-type conditions.

One significant difference between engineered and wild-type cassava did emerge in the study. Using high-performance liquid chromatography (HPLC), the research group established that the vitamin B6 that accumulated in the engineered cassava plants' leaves and roots was mostly in the unphosphorylated form. Only the phosphorylated esters of vitamin B6 are active in the body, but the unphosphorylated forms of vitamin B6 are more stable to storage and to heating. Cassava is typically boiled before eating to remove toxic compounds known as cyanogens, and quite a bit (15%, up to 75%) of the vitamin B6 in cassava can be lost due to boiling (9, see also 1, at page 1031). Thus, having a cassava plant with enhanced vitamin B6 production means that more vitamin B6 will be available to the eater after the plant is cooked.

Finally, the authors examined the bioavailability of the vitamin B6 produced by the genetically engineered plants and found that the vitamin B6 produced by the transgenic cassava was highly available to be absorbed by the consumer of the cassava. Indeed, the authors noted that "[u]sing bioavailable 'vitamin B6 equivalents', we calculated that the vitamin B6 recommended dietary allowance for an adult person (1.3 mg/day) would be reached with 51 g of boiled 35S-5 leaves or 505 g (~1.7 lb) of boiled PAT-12 storage roots" (1, at page 1031).

This paper shows that cassava, an important dietary staple, can be genetically engineered to produce more vitamin B6. The increased amounts of vitamin B6 will help alleviate nutritional deficiencies in Africa, improving the health and well-being of people who depend on cassava as a key component of their diet. Further, other modifications to cassava are possible to further improve the nutritional quality of this important plant. Finally, as noted in the press release (see the first link in this post), the researchers have not patented their technology as they want to make it freely available to everyone who needs access to the improved varieties of cassava. The groups involved in this research are now working with African scientists to try and introduce this modified cassava to African farmers.


(1) Kuan-Te Li, et al. Increased bioavailable vitamin B6 in field-grown transgenic cassava for dietary sufficiency. Nature Biotechnology 33, 1029–1032 (2015), doi:10.1038/nbt.3318. (paywall)

(2) Ian S. Blagbrough, Soad A.L. Bayoumi, Michael G. Rowan, and John R. Beeching. Cassava: An appraisal of its phytochemistry and its biotechnological prospects. Phytochemistry 71, 1940–1951 (2010), doi:10.1016/j.phytochem.2010.09.001 

(3) Cassava. (2015, October 28). In Wikipedia, The Free Encyclopedia. Retrieved 20:23, November 1, 2015, from

(4) Montagnac, J. A., Davis, C. R. and Tanumihardjo, S. A. Nutritional Value of Cassava for Use as a Staple Food and Recent Advances for Improvement. Comprehensive Reviews in Food Science and Food Safety, 8, 181–194 (2009). doi: 10.1111/j.1541-4337.2009.00077.x. #openaccess paper available at 

5. Martina Newell McGloughlin. Modifying agricultural crops for improved nutrition. New Biotechnology 27(5), 494-504 (November 2010). Available at 

6. Teresa B. Fitzpatrick, et al. Vitamin Deficiencies in Humans: Can Plant Science Help? The Plant Cell, 24, 395–414 (February 2012). #openaccess available at 

7. Hervé Vanderschuren, et al. Strategies for vitamin B6 biofortification of plants. Front Plant Sci. 4, 143 (May 2013). Available at 

8. Arabidopsis thaliana. (2015, October 27). In Wikipedia, The Free Encyclopedia. Retrieved 20:42, November 1, 2015, from

9. A.Paula Cardoso, et al. Processing of cassava roots to remove cyanogens. Journal of Food Composition and Analysis, 18(5), 451-460 (August 2005). Available at and at
2 comments on original post
Alice Quinn's profile photoscott cheston's profile photoangel cavazos's profile photomohamed jalloh's profile photo
Also they should continue research how this plant can be grown in other parts of the world ! 
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