ideas

Limits of the diaphane. But he adds: in bodies.

29.jpg

The ship of Theseus is a thought experiment that raises the question of whether a ship that has had all of its components replaced remains fundamentally the same object.

Suppose that the famous ship sailed by the hero Theseus in a great battle has been kept in a harbour as a museum piece. As the years go by some of the wooden parts begin to rot and are replaced by new ones. After a century or so, all of the parts have been replaced. Is the “restored” ship still the same object as the original?

{ Wikipedia | Continue reading }

Does the Human Body Really Replace Itself Every 7 Years?

Recent research has confirmed that different tissues in the body replace cells at different rates, and some tissues never replace cells. So the statement that we replace every cell in the body every seven years or every ten years is wrong. […]

Neurons in the cerebral cortex are never replaced.

Fat cells are replaced at the rate of about 10% per year in adults. […]

Cardiomyocyte cells [muscle cells of the heart] are replaced at a reducing rate as we age. At age 25, about 1% of cells are replaced every year. Replacement slows gradually to about 0.5% at age 70. Even in people who have lived a very long life, less than half of the cardiomyocyte cells have been replaced. Those that aren’t replaced have been there since birth.

{ Ask a Naturalist | Continue reading }

Your lungs are six weeks old - and your taste buds just ten days! […]

Liver cells only have a life span of around 150 days. […] “I can take 70 per cent of a person’s liver away in an operation and around 90 per cent of it will grow back within two months,” explains David Lloyd, consultant liver surgeon at Leicester Royal Infirmary. […]

Your eyes are one of the few body parts that don’t really change during your life. The only part that is constantly being renewed is the cornea, the transparent top layer.

{ Daily Mail | Continue reading }

A collection of the replacement rates of different cells in our body:

490-t1-cellsbodyreplacementrate-16.png

[…]

We note that hair elongates at about 1 cm per month while fingernails grow at about 0.3 cm per month, which is about the same speed as the continental spreading in plate tectonics that increases the distance between North America and Europe.

{ Cell Biology by the Numbers | Continue reading }

For decades, scientists believed that neurogenesis—the creation of new neurons—whirs along nicely in the brains of embryos and infants, but grinds to a halt by adulthood. But from the 1980s onward, this dogma started to falter. Researchers showed that neurogenesis does occur in the brains of various adult animals, and eventually found signs of newly formed neurons in the adult human brain. Hundreds of these cells are supposedly added every day to the hippocampus—a comma-shaped structure involved in learning and memory. The concept of adult neurogenesis is now so widely accepted that you can find diets and exercise regimens that purportedly boost it.

The trouble is: This stream of fresh neurons might not actually exist.

In a new study, and one of the biggest yet, a team led by Arturo Alvarez-Buylla at the University of California at San Francisco completely failed to find any trace of young neurons in dozens of hippocampus samples, collected from adult humans.

{ The Atlantic, March 2018 | Continue reading }

People as old as 79 may still generate new brain cells, US researchers said Thursday. […] Using autopsied brain samples from 28 people who died suddenly between the ages of 14-79, researchers looked at “newly formed neurons and the state of blood vessels within the entire human hippocampus soon after death.” […]

A study last month led by Arturo Alvarez-Buylla of the University of California in San Francisco found the opposite, however.

{ Medical Express, April 2018 | Continue reading }

The generation of cells in the human body has been difficult to study, and our understanding of cell turnover is limited. Testing of nuclear weapons resulted in a dramatic global increase in the levels of the isotope 14C in the atmosphere, followed by an exponential decrease after 1963.

We show that the level of 14C in genomic DNA closely parallels atmospheric levels and can be used to establish the time point when the DNA was synthesized and cells were born. We use this strategy to determine the age of cells in the cortex of the adult human brain and show that whereas nonneuronal cells are exchanged, occipital neurons are as old as the individual, supporting the view that postnatal neurogenesis does not take place in this region.

{ Cell | PDF }

If the cells of our skin are replaced regularly, why do scars and tattoos persist indefinitely?

The cells in the superficial or upper layers of skin, known as the epidermis, are constantly replacing themselves. This process of renewal is basically exfoliation (shedding) of the epidermis. But the deeper layers of skin, called the dermis, do not go through this cellular turnover and so do not replace themselves. Thus, foreign bodies, such as tattoo dyes, implanted in the dermis will remain.

{ Scientific American | PDF }

inkjet and acrylic on canvas { imp kerr (b.1980), not confirmed as alive, 59th st, nyc, 1977, 2018 }

This is being marketed as “psychedelic soul,” and while it has some rock trappings, I’m having a hard time finding the psych in this

33.jpg

a lot of luck comes from doing things that are interesting, and sort of creating your own luck

{ Eric Schmidt | Continue reading }

image { Bill Arsenault, Nonplussed Some Some More exhibition poster, 1969 }

The winner takes it all

6.jpg

People often conduct visual searches in which multiple targets are possible (e.g., medical x-rays can contain multiple abnormalities). In this type of search, observers are more likely to miss a second target after having found a first one.

{ PsyArXiv | Continue reading }

The streetlight effect, or the drunkard’s search principle, is a type of observational bias that occurs when people only search for something where it is easiest to look.

{ Wikipedia | Continue reading }

Modern scientific instruments can extensively process “observations” before they are presented to the human senses, and particularly with computerized instruments, there is sometimes a question as to where in the data processing chain “observing” ends and “drawing conclusions” begins. This has recently become an issue with digitally enhanced images published as experimental data in papers in scientific journals. The images are enhanced to bring out features that the researcher wants to emphasize, but this also has the effect of supporting the researcher’s conclusions.

{ Wikipedia | Continue reading }

related { Errors/Biases in Clinical Decision Making }

photo { Richard Avedon, Christy Turlington for Revlon, 1990 }

The man who invented autocorrect should burn in hello

imp-kerr-looped-breathing-tubes.jpg

50% of human experience has happened after 1309 AD. 15% of all experience has been experienced by people who are alive right now. […]

{ Eukaryote Writes Blog | Continue reading }

inkjet and acrylic on canvas { imp kerr, looped breathing tubes, 2018 }

‘If it ain’t broke, don’t fix it.’ –Ronald Reagan

221.jpg

“What are the odds, if everything is random?” Wang wondered.

In a new paper, Wang investigates whether “hot-streak” periods are more than just a lucky coincidence. […]

Looking at the career histories of thousands of scientists, artists, and film directors, the team found evidence that hot streaks are both real and ubiquitous, with virtually everyone experiencing one at some point in their career. While the timing of an individual’s greatest successes is indeed random, their top hits are highly likely to appear in close proximity. […]

“If we know where your best work is, then we know very well where your second-best work is, and your third,” he says, “because they’re just around the corner.”

{ Kellogg School of Management | Continue reading }

On ne sait pas ce que peut le corps

544.jpg

The new “eyes wide shut” illusion uses a standard enlarging (shaving or makeup) mirror. Close one eye and look at the closed eye in the mirror; the eye should take up most of the mirror. Switch eyes to see the other closed eye. Switch back-and-forth a few times, then open both eyes. You see an open eye. Which eye is it? To find out, close one eye. Whichever you close, that’s the eye you see. How can this be possible? The brain is fusing two images of the two eyes.

{ Perception | Continue reading | Thanks Brad! }

However, no one has hitherto laid down the limits to the powers of the body, that is, no one has as yet been taught by experience what the body can accomplish solely by the laws of nature, in so far as she is regarded as extension. No one hitherto has gained such an accurate knowledge of the bodily mechanism, that he can explain all its functions; nor need I call attention to the fact that many actions are observed in the lower animals, which far transcend human sagacity, and that somnambulists do many things in their sleep, which they would not venture to do when awake: these instances are enough to show, that the body can by the sole laws of its nature do many things which the mind wonders at.

Again, no one knows how or by what means the mind moves the body, nor how many various degrees of motion it can impart to the body, nor how quickly it can move it.

{ Spinoza, Ethics, III, Proposition II, Scholium | Continue reading }

unrelated { eye colour may not be a priority when choosing a partner }

I see, lady, the gentleman is not in your books

43.jpg

The familiarity of the phrase ‘much ado about nothing’ belies its complexity. In Shakespeare’s day ‘nothing’ was pronounced the same as ‘noting’, and the play contains numerous punning references to ‘noting’, both in the sense of observation and in the sense of ‘notes’ or messages. […]

‘Nothing’ was Elizabethan slang for the vagina (a vacancy, ‘no-thing’ or ‘O thing’). Virginity — a state of potentiality rather than actuality — is also much discussed in the play, and it is these twin absences — the vagina and virginity — that lead, in plot terms, to the ‘much ado’ of the title.

{ The Guardian | Continue reading }

photo { Olivia Rocher, I Fought the Law (Idaho), 2016 }

‘Time is a waste of money.’ –Oscar Wilde

74635.jpg

What happens when we unexpectedly see an attractive potential partner? Previous studies in laboratorial settings suggest that the visualization of attractive and unattractive photographs influences time. The major aim of this research is to study time perception and attraction in a realistic social scenario, by investigating if changes in subjective time measured during a speed dating are associated with attraction. […]

When there is a perception of the partner as being physically more attractive, women tend to overestimate the duration of that meeting, whereas men tend to underestimate its duration.

{ University of Minho | Continue reading }

On his wise shoulders through the checkerwork of leaves the sun flung spangles, dancing coins

dusty.jpg

Two theoretical frameworks have been proposed to account for the representation of truth and falsity in human memory: the Cartesian model and the Spinozan model. Both models presume that during information processing a mental representation of the information is stored along with a tag indicating its truth value. However, the two models disagree on the nature of these tags. According to the Cartesian model, true information receives a “true” tag and false information receives a “false” tag. In contrast, the Spinozan model claims that only false information receives a “false” tag, whereas untagged information is automatically accepted as true. […]

The results of both experiments clearly contradict the Spinozan model but can be explained in terms of the Cartesian model.

{ Memory & Cognition | PDF }

art { Richard Long, Dusty Boots Line, The Sahara, 1988 }

‘It depends on what the meaning of the word is is.’ –Bill Clinton

How do we navigate a deeply structured world? Why are you reading this sentence first - and did you actually look at the fifth word?

{ Neuroscience & Biobehavioral Reviews | Continue reading }

‘The trouble with comparing yourself to others is that there are too many others.’ –Sarah Manguso

26.jpg

The Game is a mental game where the objective is to avoid thinking about The Game itself. Thinking about The Game constitutes a loss. 

{ Wikipedia | Continue reading }

art { Taryn Simon, Finance package for the construction of the Baku-Tbilisi-Ceyhan pipeline. Baku, Azerbaijan, February 3, 2004, Paperwork and the Will of Capital, 2015 | Ralph Gibson, Beautiful Parlor, 1968 }

To remind me of. Lff!

21.jpg

Let’s begin with a simple fact: time passes faster in the mountains than it does at sea level. The difference is small but can be measured with precision timepieces that can be bought today for a few thousand pounds. This slowing down can be detected between levels just a few centimetres apart: a clock placed on the floor runs a little more slowly than one on a table.

It is not just the clocks that slow down: lower down, all processes are slower. Two friends separate, with one of them living in the plains and the other going to live in the mountains. They meet up again years later: the one who has stayed down has lived less, aged less, the mechanism of his cuckoo clock has oscillated fewer times. He has had less time to do things, his plants have grown less, his thoughts have had less time to unfold … Lower down, there is simply less time than at altitude. […]

Times are legion: a different one for every point in space. The single quantity “time” melts into a spiderweb of times.

{ Guardian | Continue reading }

photo { Julie Blackmon }