12 Snipers From The Soviet 3rd Shock Army With 775 Confirmed Kills. Germany, May 4th 1945.

Aphasia: The disorder that makes you lose your words

It’s hard to imagine being unable to turn thoughts into words. But, if the delicate web of language networks in your brain became disrupted by stroke, illness or trauma, you could find yourself truly at a loss for words. This disorder, called “aphasia,” can impair all aspects of communication. Approximately 1 million people in the U.S. alone suffer from aphasia, with an estimated 80,000 new cases per year.  About one-third of stroke survivors suffer from aphasia, making it more prevalent than Parkinson’s disease or multiple sclerosis, yet less widely known.

There are several types of aphasia, grouped into two categories: fluent (or “receptive”) aphasia and non-fluent (or “expressive”) aphasia. 

People with fluent aphasia may have normal vocal inflection, but use words that lack meaning. They have difficulty comprehending the speech of others and are frequently unable to recognize their own speech errors. 

People with non-fluent aphasia, on the other hand, may have good comprehension, but will experience long hesitations between words and make grammatical errors. We all have that “tip-of-the-tongue” feeling from time to time when we can’t think of a word. But having aphasia can make it hard to name simple everyday objects.  Even reading and writing can be difficult and frustrating.

It’s important to remember that aphasia does not signify a loss in intelligence. People who have aphasia know what they want to say, but can’t always get their words to come out correctly. They may unintentionally use substitutions, called “paraphasias” – switching related words, like saying dog for cat, or words that sound similar, such as house for horse. Sometimes their words may even be unrecognizable.  

So, how does this language-loss happen? The human brain has two hemispheres. In most people, the left hemisphere governs language.  We know this because in 1861, the physician Paul Broca studied a patient who lost the ability to use all but a single word: “tan.” During a postmortem study of that patient’s brain, Broca discovered a large lesion in the left hemisphere, now known as “Broca’s area.” Scientists today believe that Broca’s area is responsible in part for naming objects and coordinating the muscles involved in speech. Behind Broca’s area is Wernicke’s area, near the auditory cortex. That’s where the brain attaches meaning to speech sounds. Damage to Wernicke’s area impairs the brain’s ability to comprehend language. Aphasia is caused by injury to one or both of these specialized language areas.

Fortunately, there are other areas of the brain which support these language centers and can assist with communication.  Even brain areas that control movement are connected to language. Our other hemisphere contributes to language too, enhancing the rhythm and intonation of our speech. These non-language areas sometimes assist people with aphasia when communication is difficult.

However, when aphasia is acquired from a stroke or brain trauma, language improvement may be achieved through speech therapy.  Our brain’s ability to repair itself, known as “brain plasticity,” permits areas surrounding a brain lesion to take over some functions during the recovery process. Scientists have been conducting experiments using new forms of technology, which they believe may encourage brain plasticity in people with aphasia.  

Meanwhile, many people with aphasia remain isolated, afraid that others won’t understand them or give them extra time to speak. By offering them the time and flexibility to communicate in whatever way they can, you can help open the door to language again, moving beyond the limitations of aphasia.

What was your favorite prop or costume from the “Harry Potter” films?

“Men want to beat me. I play men, six, seven hours a day. Men… they do not beat me.”

- Masako “Katsy” Katsura, first woman to compete for a world’s title in billiards

The “First Lady of Billiards” learned from her brother-in-law and in the 50s became Japan’s only female billiards pro. She paved the way for women to come, then left the spotlight and lived a quiet life. She died in 1995.

fangtooth moray photos by Sacha Lobenstein

Christ the Redeemer (Portuguese: Cristo Redentor) is an Art Deco statue of Jesus Christ in Rio de Janeiro, Brazil, created by French sculptor Paul Landowski and built by the Brazilian engineer Heitor da Silva Costa, in collaboration with the French engineer Albert Caquot. It is 30 metres (98 ft) tall, not including its 8-metre (26 ft) pedestal, and its arms stretch 28 metres (92 ft) wide.

The statue weighs 635 metric tons (625 long, 700 short tons), and is located at the peak of the 700-metre (2,300 ft) Corcovadomountain in the Tijuca Forest National Park overlooking the city of Rio. As a symbol of Brazilian Christianity, the statue has become an icon for Rio de Janeiro and Brazil. It is made of reinforced concrete and soapstone, and was constructed between 1922 and 1931.

The statue of Christ the Redeemer with open arms, a symbol of peace, was chosen. Local engineer Heitor da Silva Costa designed the statue; it was sculpted by Polish-French sculptor Paul Landowski. Gheorghe Leonida contributed by portraying Jesus Christ’s face on the statue, which made him famous.

A group of engineers and technicians studied Landowski’s submissions and the decision was made to build the structure out of reinforced concrete (designed by Albert Caquot) instead of steel, more suitable for the cross-shaped statue. The outer layers are soapstone, chosen for its enduring qualities and ease of use. Construction took nine years, from 1922 to 1931 and cost the equivalent of US$250,000 ($3,300,000 in 2015). The monument was opened on October 12, 1931.During the opening ceremony, the statue was lit by a battery of floodlights turned on remotely by shortwave radio pioneer Guglielmo Marconi, stationed 5,700 miles (9,200 km) away in Rome.(x)

Tough as a Tardigrade

Without water, a human can only survive for about 100 hours. But there’s a creature so resilient that it can go without it for decades. This one millimeter animal can survive both the hottest and coldest environments on Earth, and can even withstand high levels of radiation. This is the tardigrade, and it’s one of the toughest creatures on Earth, even if it does look more like a chubby, eight-legged gummy bear. 

Most organisms need water to survive. Water allows metabolism to occur, which is the process that drives all the biochemical reactions that take place in cells. But creatures like the tardigrade, also known as the water bear, get around this restriction with a process called anhydrobiosis, from the Greek meaning life without water. And however extraordinary, tardigrades aren’t alone. Bacteria, single-celled organisms called archaea, plants, and even other animals can all survive drying up.

For many tardigrades, this requires that they go through something called a tun state. They curl up into a ball, pulling their head and eight legs inside their body and wait until water returns. It’s thought that as water becomes scarce and tardigrades enter their tun state, they start synthesize special molecules, which fill the tardigrade’s cells to replace lost water by forming a matrix. 

Components of the cells that are sensitive to dryness, like DNA, proteins, and membranes, get trapped in this matrix. It’s thought that this keeps these molecules locked in position to stop them from unfolding, breaking apart, or fusing together. Once the organism is rehydrated, the matrix dissolves, leaving behind undamaged, functional cells.

Beyond dryness, tardigrades can also tolerate other extreme stresses: being frozen, heated up past the boiling point of water, high levels of radiation, and even the vacuum of outer space. This has led to some erroneous speculation that tardigrades are extraterrestrial beings.

While that’s fun to think about, scientific evidence places their origin firmly on Earth where they’ve evolved over time. In fact, this earthly evolution has given rise to over 1100 known species of tardigrades and there are probably many others yet to be discovered. And because tardigrades are so hardy, they exist just about everywhere. They live on every continent, including Antarctica. And they’re in diverse biomes including deserts, ice sheets, the sea fresh water, rainforests, and the highest mountain peaks. But you can find tardigrades in the most ordinary places, too, like moss or lichen found in yards, parks, and forests. All you need to find them is a little patience and a microscope.

Scientists are now to trying to find out whether tardigrades use the tun state, their anti-drying technique, to survive other stresses. If we can understand how they, and other creatures, stabilize their sensitive biological molecules, perhaps we could apply this knowledge to help us stabilize vaccines, or to develop stress-tolerant crops that can cope with Earth’s changing climate. 

And by studying how tardigrades survive prolonged exposure to the vacuum of outer space, scientists can generate clues about the environmental limits of life and how to safeguard astronauts. In the process, tardigrades could even help us answer a critical question: could life survive on planets much less hospitable than our own?

From the TED-Ed Lesson Meet the tardigrade, the toughest animal on Earth - Thomas Boothby

Animation by Boniato Studio

Could you explain this tfw no ZF joke? I really dont get it... :D

Get ready for a long explanation! For everyone’s reference, the joke (supplied by @awesomepus​) was:

Q: What did the mathematician say when he encountered the paradoxes of naive set theory?A: tfw no ZF

You probably already know the ‘tfw no gf’ (that feel when no girlfriend) meme, which dates to 2010. I’m assuming you’re asking about the ZF part.

Mathematically, ZF is a reference to Zermelo-Fraenkel set theory, which is a set of axioms commonly accepted by mathematicians as the foundation of modern mathematics. As you probably know if you’ve taken geometry, axioms are super important: they are basic assumptions we make about the world we’re working in, and they have serious implications for what we can and can’t do in that world. 

For example, if you don’t assume the Parallel Postulate (that consecutive interior angle measures between two parallel lines and a transversal sum to 180°, or twice the size of a right angle), you can’t prove the Triangle Angle Sum Theorem (that the sum of the angle measures in any triangle is also 180°). It’s not that the Triangle Angle Sum Theorem theorem is not true without the Parallel Postulate — simply that it is unprovable, or put differently, neither true nor false, without that Postulate. Asking whether the Triangle Angle Sum Theorem is true without the Parallel Postulate is really a meaningless question, mathematically. But we understand that, in Euclidean geometry (not in curved geometries), both the postulate and the theorem are “true” in the sense that we have good reason to believe them (e.g., measuring lots of angles in physical parallel lines and triangles). Clearly, the axioms we choose are important.

Now, in the late 19th and early 20th century, mathematicians and logicians were interested in understanding the underpinnings of the basic structures we use in math — sets, or “collections,” being one of them, and arithmetic being another. In short, they were trying to come up with an axiomatic set theory. Cantor and Frege were doing a lot of this work, and made good progress using everyday language. They said that a set is any definable collection of elements, where “definable” means to provide a comprehension (a term you’re familiar with if you program in Python), or rule by which the set is constructed.

But along came Bertrand Russell. He pointed out a big problem in Cantor and Frege’s work, which is now called Russell’s paradox. Essentially, he made the following argument:

Y’all are saying any definable collection is a set. Well, how about this set: R, the set of all sets not contained within themselves. This is, according to you, a valid set, because I gave that comprehension. Now, R is not contained within itself, naturally: if it is contained within itself, then it being an element is a violation of my construction of R in the first place. But R must be contained within itself: if it’s not an element of itself, then it is a set that does not contain itself, and therefore it is an element of itself. So we have that R ∈ R and also R ∉ R. This is a contradiction! Obviously, your theory is seriously messed up.

This paradox is inherently a part of Cantor and Frege’s set theory — it shows that their system was inconsistent (with itself). As Qiaochu Yuan explains over at Quora, the problem is exactly what Russell pointed out: unrestricted comprehension — the idea that you can get away with defining any set you like simply by giving a comprehension. Zermelo and Fraenkel then came along and offered up a system of axioms that formalizes Cantor and Frege’s work logically, and restricts comprehension. This is called Zermelo-Fraenkel set theory (or ZF), and it is consistent (with itself). Cantor and Frege’s work was then retroactively called naive set theory, because it was, of course, pretty childish:

There are two more things worth knowing about axiomatic systems in mathematics. First, some people combine Zermelo-Fraenkel set theory with the Axiom of Choice¹, resulting in a set theory called ZFC. This is widely used as a standard by mathematicians today. Second, Gödel proved in 1931 that no system of axioms for arithmetic can be both consistent and complete — in every consistent axiomatization, there are “true” statements that are unprovable. Or put another way: in every consistent axiomatic system, there are statements which you can neither prove nor disprove.For example, in ZF, the Axiom of Choice is unprovable — you can’t prove it from the axioms in ZF. And in both ZF and ZFC, the continuum hypothesis² is unprovable.³ Gödel’s result is called the incompleteness theorem, and it’s a little depressing, because it means you can’t have any good logical basis for all of mathematics (but don’t tell anyone that, or we might all be out of a job). Luckily, ZF or ZFC has been good enough for virtually all of the mathematics we as a species have done so far!

The joke is that, when confronted with Russell’s paradox in naive set theory, the mathematician despairs, and wishes he could use Zermelo-Fraenkel set theory instead — ‘that feel when no ZF.’

I thought the joke was incredibly funny, specifically because of the reference to ‘tfw no gf’ and the implication that mathematicians romanticize ZF (which we totally do). I’ve definitely borrowed the joke to impress friends and faculty in the math department…a sort of fringe benefit of having a math blog.

– CJH

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Plantigrade vs. Digitigrade Carnivores - the Polar Bear and the African Lion

The foot structure of many animals plays a critical role in their locomotion and environmental niche, and in carnivores, the clear distinction between plantigrade (walking with the podials and metatarsals both flat on the ground) and digitigrade (walking on the toes, with the heel and wrist permanently raised) animals is most evident.

In plantigrade beasts - which include humans, many rodents, bears, racoons, and opossums - the larger surface area that the many bones provide can act as both a stabilizer and a very effective bearer of great weights. In fact, the big ol’ flighted dinosaurs were plantigrade. At the same time, so were the first (and relatively small) mammals, since both of them needed lots of stability in their feet. The weight-bearing ability and stable platform comes at the cost of speed, as the energy and requirements for movement of so many bones and muscles is much greater than digitigrade feet or unguligrade feet.

Digitigrade animals walk on only their toes, leaving their wrists and ankles permanently raised. This affords more speed, much more silent movement. Cats, birds, and dogs are digitigrade. Digitigrade feet evolved long after plantigrade feet, to fit the niche of mid-sized carnivores. However, they cannot effectively sustain large loads, which is why you cannot use a lion as a pack mule. Well, among other reasons. Really, you just don’t want to try using any mid-sized (or large, in the lion’s case) carnivore as a pack mule.

On the Anatomy of Vertebrates. Richard Owen, 1866.

Survivorship Bias

I have posted about survivorship bias and how it affects your career choices: how a Hollywood actor giving the classic “follow your dreams and never give up” line is bad advice and is pure survivorship bias at work.

When I read up on the wikipedia page, I encountered an interesting story:

During WWII the US  Air Force wanted to minimize bomber losses to enemy fire. The Center for Naval Analyses ran a research on where bombers tend to get hit with the explicit aim of enforcing the parts of the airframe that is most likely to receive incoming fire. This is what they came up with:

So, they said: the red dots are where bombers are most likely to be hit, so put some more armor on those parts to make the bombers more resilient. That looked like a logical conclusion, until Abraham Wald - a mathematician - started asking questions: 

- how did you obtain that data? - well, we looked at every bomber returning from a raid, marked the damages on the airframe on a sheet and collected the sheets from all allied air bases over months. What you see is the result of hundreds of those sheets. - and your conclusion? - well, the red dots are where the bombers were hit. So let’s enforce those parts because they are most exposed to enemy fire.  - no. the red dots are where a bomber can take a hit and return. The bombers that took a hit to the ailerons, the engines or the cockpit never made it home. That’s why they are absent in your data. The blank spots are exactly where you have to enforce the airframe, so those bombers can return.

This is survivorship bias. You only see a subset of the outcomes. The ones that made it far enough to be visible. Look out for absence of data. Sometimes they tell a story of their own.

BTW: You can see the result of this research today. This is the exact reason the A-10 has the pilot sitting in a titanium armor bathtub and has it’s engines placed high and shielded.

Harmonograph, H. Irwine Whitty, 1893

“The facts that musical notes are due to regular air-pulses, and that the pitch of the note depends on the frequency with which these pulses succeed each other, are too well known to require any extended notice. But although these phenomena and their laws have been known for a very long time, Chladni, late in the last century, was the first who discovered that there was a connection between sound and form.”

source here