Is psychology a young or mature science?

"There's a thought that's haunted me for years: we're doing all this research in psychology, but are we learning anything? We run these studies and publish these papers and...then what? The stack of papers just gets taller?"

"I've got this picture in my head: we're all on a bus that's supposedly going to Cincinnati. But there are no road signs and we don't have a GPS, so we have no idea if we're going in the right direction. We can't measure our progress by how much gas we're burning, or whether we've upgraded from a manual transmission to an automatic, or whether the government bought us a new bus. And you can't just look out the window and go, 'I dunno, kinda feels like we're headed toward Arkansas,' which, I realize now, is what I've been doing so far."

"Instead, you first gotta ask: how could we know we're getting closer to Cincinnati?"

"In my estimation, there are five ways to measure psychology's progress, and we are succeeding in exactly one of them."

The 5 are:

1. Overturning intuitions,

2. Pitting people armed with the psychological literature and against people armed only with their own intuitions,

3. Helping people make better decisions,

4. Producing useful technology, and

5. Seeing old ideas become nonsensical after paradigm shifts.

"The philosopher Michael Strevens says that doing science requires an 'alien mindset' where you entertain ridiculous thoughts like 'perhaps Aristotle needs some updating' or 'maybe we should toss balls of varying weights off a tower and see which one hits the ground first.' Those thoughts don't seem alien anymore, of course, because they worked out. But going full alien-brain today means you will have to entertain thoughts that incur reputational risk, like 'maybe you don't have to pay attention to the literature' and 'maybe we should ask people how their toothbrush could be different'. Once you get into the alien mindset, the best thing to think about is mysteries. What are the self-evident phenomena: things that definitely happen, but that we cannot explain?"

Is psychology going to Cincinnati? - by Adam Mastroianni

#discoveries #psychology

"A headset-based device that can be used to noninvasively assess a patient's stroke risk by monitoring changes in blood flow and volume while a participant holds their breath" has been developed.

The innovation here is (believe it or not) not AI -- it's a laser and camera setup.

"Stroke is caused by the blockage or rupture of an artery in the brain, which results in a reduction in blood flow. Starved of oxygen, the brain's cells die rapidly -- about 2 million every minute during a stroke."

"The Caltech team developed a compact device that shines infrared laser light through the skull and into the brain in one location and then uses a special camera nearby to collect the light that bounces back after it is scattered by blood flowing within the blood vessels. The approach, called speckle contrast optical spectroscopy (SCOS), measures the decrease in the light's intensity from the spot where it enters the skull to the place where the bounced-back light is collected to determine the volume of blood in the brain's blood vessels; it also looks at the way light scatters and creates speckles in the camera's field of view. The speckles fluctuate in images depending on the rate of blood flow in the blood vessels. The faster the blood is flowing, the more rapidly the speckle field changes."

"The researchers can use those measurements to calculate a ratio of the flow over the volume of blood streaming through the vessel to get an idea of that patient's stroke risk."

"Holding your breath stresses your brain as it begins to notice that it is taking in too much carbon dioxide and not enough oxygen. It goes into what Mahler refers to as 'panic mode,' and starts to pump oxygen from the rest of the body to itself. This greatly increases blood flow in the brain. Once you stop holding your breath, oxygen levels return to baseline. While this happens in both people at low and high risk of stroke, the researchers found that there were differences between the groups in terms of how the blood moved through the vessels."

"The SCOS technique allows the researchers to measure how much the blood vessels expand while the subject holds their breath and how much faster blood flows through the vessels in response. 'These reactive measurements are indicative of vessel stiffness,' Yang says. 'Our technology makes it possible to make these type of measurements noninvasively for the first time.'"

New laser-based headset can measure blood flow, assess risk of stroke

#discoveries #medical #spectroscopy

"The Body Roundness Index is a novel body composition measurement that is touted as being a more accurate alternative to Body Mass Index."

The calculation is based on height and weight, and waist and hip circumference.

"In a large retrospective study of 33,000 US adults, researchers found a 'U-shaped' curve, indicating those with a Body Roundness Index below and above the normal range had an increased risk of death from any cause."

So... don't be a ball... or a twig.

Is the Body Roundness Index the New BMI?

#discoveries #medicine

Transparent mice.

"The addition of common dye molecules that absorb in the near ultraviolet and blue regions improve optical transparency in nearby longer wavelengths. In essence, by causing sharp absorption in the blue region, the refractive index in the red part of the spectrum is increased without increasing absorption."

"By applying the Lorentz oscillator model for the dielectric properties of tissue components and absorbing molecules, we predicted that dye molecules with sharp absorption resonances in the near-ultraviolet spectrum (300 to 400 nm) and blue region of the visible spectrum (400 to 500 nm) are effective in raising the real part of the refractive index of the aqueous medium at longer wavelengths when dissolved in water, which is in agreement with the Kramers-Kronig relations. As a result, water-soluble dyes can effectively reduce the refractive index contrast between water and lipids, leading to optical transparency of live biological tissues."

The dye molecule they used? Tartrazine. Also known as "Yellow 5". Used in Doritos.

"So far, the scientists behind the new discovery have used the method to see the organs in a mouse's intact abdomen, glimpse the pulsing vessels surrounding a rodent skull, and to get an exceptionally clear view of muscle tissue through a microscope."

The dye in Doritos can make mice transparent | Popular Science

#discoveries #biology #biotech #microscopy

"A new tool shows how much air quality has changed since the Industrial Revolution in cities across the world. It generates a single image made up of different colored stripes representing pollution each year in each major city."

I wondered how they go all the way back to the 1800s. Nobody had pollution sensors back then, did they?

"Satellite and ground-level readings of PM2.5 provide data for roughly the past two decades. Since that was largely lacking before 2000, they also rely on computer model simulations to peer back in time."

So they've really only got about 20 years of real data -- the rest is guesswork. And PM2.5 isn't all there is to air quality. But it's a start.

Scroll down and have a look at Delhi, India. :O OMG.

Clicking through to the website, I found some other pretty shocking cities: Dhaka, Bangladesh. Ulaanbaatar, Mongolia. Doha, Qatar. Riyadh, Saudi Arabia.

I somehow thought, air quality, around the world, in general, was trending towards improvement. But clicking around this site, now I don't think so. It seems a lot more random. And if you want really good air quality, go to a remote island somewhere. New Zealand. Iceland. Etc.

Hope and disparity: a colorful new way to visualize air quality around the world

#discoveries #environment

"Psychedelics reopen the social reward learning critical period."

This came out last year but I only found out about it today.

"During specific periods of brain development, the nervous system exhibits heightened sensitivity to ethologically relevant stimuli, as well as increased malleability for synaptic, circuit and behavioural modifications."

"Ethologically relevant" means... relevant to how an animal relates to its natural environment?

"These mechanistically constrained windows of time are called critical periods and neuroscientists have long sought methods to reopen them for therapeutic benefit. Recently, we have discovered a novel critical period for social reward learning and shown that the empathogenic psychedelic MDMA is able to reopen this critical period. This mechanism shares a number of features with the therapeutic effects of MDMA-assisted psychotherapy for the treatment of PTSD, including rapid onset, durability and context dependence."

Ok, so this experiment is based on a technique called "social reward conditioned place preference" for mouse experiments.

"Mice were socially housed (3-5 males) in a cage containing corncob bedding until the pre-determined age for social reward conditioned place preference testing. Each mouse was used for only one behavioural time point. At the pre-determined age, mice were placed in an open field activity chamber equipped with infrared beams and a software interface to monitor the position of the mouse. The apparatus was partitioned into two equally sized zones using a clear Plexiglas wall, with a 5 cm diameter circular hole at the base; each zone contained one type of novel bedding. The amount of time spent freely exploring each zone was recorded during 30-min test sessions. For example, a score of 900 means that the mouse spent exactly 50% of its time on each of the two beddings, whereas a score of 1,800 means that it spent the full 30 min in the bedding that would be subsequently assigned as the social conditioning cue, and no time in the bedding that would be assigned as the isolation conditioning cue. After an initial pre-conditioning trial to establish baseline preference for the two sets of bedding cues, mice were assigned to receive social conditioning (with cage mates) for 24 h on one type of bedding, followed by 24 h of isolation conditioning (without cage mates) on the other bedding cue. To assure unbiased design, chamber assignments were counterbalanced for side and bedding cues. Immediately after the isolation conditioning, a 30-min post-conditioning trial was conducted to establish preference for the two conditioned cues. Conditioned place preference is a learned association between a condition (for example, social) and a cue (bedding). It does not require scent from the other mice, as the bedding itself serves as the cue."

Got that? I'm going to deliberately avoid quoting more from the paper because they use a lot of, um, chemical names that these online information distribution systems such as the one you're using right now disapprove of. (I'm going to let "MDMA" slip though and see if I get away with it.)

Basically the research shows MDMA reinstates social reward learning in a serotonin receptor 2A-independent manner.

"To directly compare treatment-related transcriptional changes specific to the shared ability of psychedelics to reopen the social reward learning critical period, we analysed the gene expression dataset between conditions in which the critical period is in the open state versus conditions where the critical period remains in or returns to the closed state. Using this approach, we identified 65 genes that were significantly differentially expressed. Gene set enrichment analysis of this list identified significant enrichment of ontologies associated with endothelial development, regulation of angiogenesis, vascular development and tissue morphogenesis. Of note, many of the top scoring genes are components of the extracellular matrix or have been implicated in its remodelling, including: Fn1, Mmp16, Trpv4, Tinagl1, Nostrin41, Cxcr4, Adgre5, Robo4 and Sema3g45."

I didn't Google all those genes to see what is known about their function but you're welcome to. I wish I had more time to study the brain, but there is so much to learn and I don't have more time to devote to it right now.

"Additionally, the differentially expressed gene set includes the immediate early genes Fos, Junb, Arc and Dusp. When we did not control for the psychedelic-specific psychoactive response, we identified 39 differentially expressed genes; however, enrichment analysis identified no significant ontologies associated with this gene set, and only 6 genes (Hspa12b, Sema3g, Eng, Flt4, Cavin1, and Ube4b) overlapped with the differentially expressed genes in the open state versus closed state dataset. These results provide evidence that the shared ability of psychedelics to reopen the social reward learning critical period converges at transcriptional regulation of the extracellular matrix. On the basis of these findings, our working model posits that psychedelics act at a diverse array of binding targets (such as sodium-dependent serotonin transporter (SERT), serotonin receptor 2A (5-HT2AR), N-methyl-d-aspartate receptor (NMDA), and kappa-opioid receptor (KOR)), to trigger a downstream signalling response that leads to activity-dependent (perhaps via immediate early genes-mediated coincidence detection) degradation of the extracellular matrix, which in turn is the permissive event that enables metaplasticity. In this model, transcriptional upregulation of extracellular matrix components (for example, Fibronectin (FN1)) and downregulation of extracellular matrix proteolytic enzymes (for example, Matrix Metalloproteinase 16 (MMP-16)), reflects the homeostatic response to these long-lasting cellular changes."

There's a lot more technical work in the paper. But basically, the researchers were able to find evidence of reopening of social learning with the "social reward conditioned place preference" technique, identify brain receptors and even an assortment of genes involved. This is all in mice. Implications for humans not yet known.

#discoveries #neuroscience #psychedelics #criticalperiod #mdma

https://www.nature.com/articles/s41586-023-06204-3

Lifespan of different species correlated with mutation rate of non-reproductive (somatic) cells. This research came out in 2022 but for some reason I only found out about it today. But it seems worth sharing as it seems a key insight into the nature of lifespan. Humans have 47 substitutions per year, while mice have 796 and live much shorter lives.

"To study somatic mutations across a diverse set of mammals, we isolated 208 individual intestinal crypts from 56 individuals across 16 species with a wide range of lifespans and body sizes: black-and-white colobus monkey, cat, cow, dog, ferret, giraffe, harbour porpoise, horse, human, lion, mouse, naked mole-rat, rabbit, rat, ring-tailed lemur, and tiger."

"We chose intestinal crypts for several reasons. First, they are histologically identifiable units that line the epithelium of the colon and small intestine and are amenable to laser microdissection. Second, human studies have confirmed that individual crypts become clonally derived from a single stem cell and show a linear accumulation of mutations with age, which enables the estimation of somatic mutation rates through genome sequencing of single crypts. Third, in most human crypts, most somatic mutations are caused by endogenous mutational processes common to other tissues, rather than by environmental mutagens."

"Across species, the mutational spectra showed clear similarities, with a dominance of cytosine-to-thymine (C>T) substitutions at CpG sites, as observed in human colon, but with considerable variation in the frequency of other substitution types."

"Across the 15 species with age information, we found that substitution rates per genome ranged from 47 substitutions per year in humans to 796 substitutions per year in mice, and indel rates from 2.5 to 158 indels per year, respectively."

"Indel", short for insertion/deletion, is a general term that may refer to any combination of insertions and deletions in DNA.

"To investigate the relationship between somatic mutation rates, lifespan and other life-history traits, we first estimated the lifespan of each species using survival curves. We used a large collection of mortality data from animals in zoos to minimize the effect of extrinsic mortality. We defined lifespan as the age at which 80% of individuals reaching adulthood have died, to reduce the effects of outliers and variable cohort sizes that affect maximum lifespan estimates. Notably, we found a tight anticorrelation between somatic mutation rates per year and lifespan across species. A log-log allometric regression yielded a strong linear anticorrelation between mutation rate per year and lifespan (fraction of inter-species variance explained = 0.85, P = 1 x 10^-6), with a slope close to and not significantly different from -1. This supports a simple model in which somatic mutation rates per year are inversely proportional to the lifespan of a species (rate is approximately equal to 1/lifespan), such that the number of somatic mutations per cell at the end of the lifespan (the end-of-lifespan burden) is similar in all species."

"To further study the relationship between somatic mutation rates and life-history variables, we used linear mixed-effects regression models. These models account for the hierarchical structure of the data (with multiple crypts per individual and multiple individuals per species), as well as the heteroscedasticity of somatic mutation rate estimates across species. Using these models, we estimated that the inverse of lifespan explained 82% of the inter-species variance in somatic substitution rates (rate = k/lifespan) (P = 2.9 x 10^-9), with the slope of this regression (k) representing the mean estimated end-of-lifespan burden across species (3,206.4 substitutions per genome per crypt, 95% confidence interval 2,683.9-3,728.9). Of note, despite uncertainty in the estimates of both somatic mutation rates and lifespans, and despite the diverse life histories of the species surveyed--including around 30-fold variation in lifespan and around 40,000-fold variation in body mass--the estimated mutation load per cell at the end of lifespan varied by only around threefold across species."

"Analogous results were obtained when repeating the analysis with estimates of the protein-coding mutation rate, which may be a better proxy for the functional effect of somatic mutations (85% of variance explained; end-of-lifespan burden: 31 coding substitutions per crypt)."

"Giraffe and naked mole-rat, for instance, have similar somatic mutation rates (99 and 93 substitutions per year, respectively), in line with their similar lifespans (80th percentiles: 24 and 25 years, respectively), despite a difference of around 23,000-fold in adult body mass. Similarly, cows, giraffes and horses weigh much more than an average human, and yet have somatic mutation rates that are several fold higher, in line with expectation from their lifespan but not their body mass."

Somatic mutation rates scale with lifespan across mammals

#discoveries #biology #genetics #dna #gwas #lifespan #longevity

15-year study says increase in vegetarianism is women-only.

"Over 15 years, students at an American university (N = 12,704) described their dietary habits. Multilevel modeling analyses (participants nested within semesters) found that overall, the percentage of vegetarians increased over time, whereas the percentage of omnivores decreased over time; however, these changes occurred only for women. The dietary habits of men did not change over time. In a second study, in a sample of 363 adult vegetarians from the US, we found that women were more likely than men to become vegetarians due to concerns about the ethics of raising animals for food and eating them, suggesting that increased societal concern about animal rights may be responsible in part for the gender differences over time in vegetarianism."

Recent increases in vegetarianism may be limited to women: A 15-year study of young adults at an American University -- Sex Roles

#discoveries #nutrition #vegetarianism #sociology

"Something is pumping out large amounts of oxygen at the bottom of the Pacific Ocean, at depths where a total lack of sunlight makes photosynthesis impossible."

"Andrew Sweetman, a sea-floor ecologist at the Scottish Association for Marine Science in Oban, UK, and his collaborators first noticed something amiss during field work in 2013. The researchers were studying sea-floor ecosystems in the Clarion-Clipperton Zone, an area between Hawaii and Mexico that is larger than India and a potential target for the mining of metal-rich nodules. During such expeditions, the team releases a module that sinks to the sea floor to perform automated experiments. Once there, the module drives cylindrical chambers down to close off small sections of the sea floor -- together with some seawater -- and create 'an enclosed microcosm of the seafloor'." "The lander then measures how the concentration of oxygen in the confined seawater changes over periods of up to several days."

"Without any photosynthetic organisms releasing oxygen into the water, and with any other organisms consuming the gas, oxygen concentrations inside the chambers should slowly fall. Sweetman has seen that happen in studies he has conducted in areas of the Southern, Arctic and Indian oceans, and in the Atlantic. Around the world, sea-floor ecosystems owe their existence to oxygen carried by currents from the surface, and would quickly die if cut off."

"But in the Clarion-Clipperton Zone, the instruments showed that the sequestered water became richer, not poorer, in oxygen. At first, Sweetman attributed the readings to a sensor malfunction. But the phenomenon kept occurring during subsequent trips in 2021 and 2022, and was confirmed by measurements with an alternative technique."

"We have another source of oxygen on the planet, other than photosynthesis."

Mystery oxygen source discovered on the sea floor -- bewildering scientists

#discoveries #oxygen #marinescience

"Some venomous snakes can bite and kill even when they're dead and decapitated."

File under "Today I learned."

"Snakes are energy-efficient creatures." "Even when their heart has stopped beating, their tissues can retain enough oxygen to allow nerves to fire, triggering a bite reflex if you put a finger in or on its mouth."

Soon, we will have CRISPR for snake venom? (see below)

Why some venomous snakes can bite and kill even when they're dead and decapitated

#discoveries #snakes

The world's biggest digital camera is 3.2 gigapixels. It weighs nearly three tons. And it was created for astronomy. It was installed in the Vera C. Rubin Observatory on the top of a mountain called Cerro Pachón in the Coquimbo region in northern Chile, on the edge of the Atacama desert.

https://gdb.voanews.com/b135c51e-f9a6-45d4-b11d-ecd7f3306330_cx0_cy10_cw0_w1200_r1.jpg

#solidstatelife #discoveries #astronomy

The harms of meditation. Wha? Meditation has harms? I never heard this.

Willoughby Britton started off as a meditation enthusiast and did her dissertation on the effects of meditation on sleep as measured by brain waves in a lab. She "knew" without any hesitation that meditation was going to improve sleep, but no, the data showed it basically caused cortical arousal and insomnia.

She didn't publish the data. "This is the wrong answer."

She went on a meditation retreat and told a meditation instructor about her lab findings, and the instructor kind of chastised her and was like, I don't know why all you clinical psychologists are trying to make meditation into a relaxation technique -- everyone knows if you meditate enough you stop sleeping.

What else do meditation teachers know that they're not telling researchers?

During one residency at an impatient psychiatric hospital there were two yogis who came off a meditation retreat completely psychotic. She went back to the same teacher and asked, have you ever seen this before? "And I just remember that I never got a verbal answer -- I just got this look that was kind of like oh... yeah we know about that... and I wish you hadn't asked..."

From there, she (Willoughby Britton) documented 59 categories of meditation related issues across seven different "domains". Here she runs through the most common. Things like making your thoughts speed up to an insane pace, or conversely, they disappear altogether so there's no thoughts at all (this is called "mind emptiness").

You can lose the ability to form concepts -- this is called "concept loss". There was a woman driving home from a meditation retreat who couldn't remember what a "red light" means.

There's perceptual hypersensitivity -- colors get brighter, sounds get louder, you can hear clocks ticking, you can hear your own breathing and the blood in your ears. Maybe in the retreat that's not so bad but you get back to the city and suddenly every car door slamming feels like it slams right through your body.

Sometimes perceptual hypersensitivity leads to hallucinations in any modality -- visual, auditory, or motor.

Meditation can amplify emotions such as fear (anxiety, paranoia), can increase rather than decrease re-experiencing of past traumas or stressful events. It can conversely lead to the loss of emotion -- that's called "affective blunting".

It can lead to bodily sensations described as "electricity energy pressure movement". It can be sufficiently overwhelming that people are unable to work.

There can be changes in sense of self. Loss of self is called "ego death" or "ego dissolution". This is actually actively sought after by certain spiritual practices.

A lot of these changes can be positive in one person but negative in another -- or can even be positive in the same person in one context and negative in another.

In North India one of her students on a Tibetan meditation retreat committed suicide, and the Buddhist concept of bodhisattva was apparently integral to it. Suicide is one of the most sensitive and least talked about issues in meditation. Meditation may reduce the likelihood of suicide in people who are suicidal to start with, but it may also increase odds of suicide in others, and it may depend on how "intensive" the meditation is.

Kundalini Awakening is an experience where sensations go up the spine, but she feels, beyond that the label is too nonspecific and can be attached to any kind of sensations. "Everything is Kundalini" so the concept is not helpful.

She feels there's this kind of bait-and-switch where people get into meditation for secular health-oriented reasons -- to manage their stress, to help them manage their emotions, to work through grief or loss -- then they experience these weird sensations and somebody says oh, it's Kundalini Awakening, and now they have to deal with chakras and all these spiritual interpretations of their experience. Meditation is marketed as "scientific" and "neuroscientific" and now suddenly people find themselves in this "magical sacred practice".

A lot of the discussion concerns how meditation is a large, for-profit industry.

Some of the hype surrounding meditation has waned because psychedelics are "the new guy on the scene". The last half hour or so of the conversation is about how she feels both should be approached as having risks and not being free of side effects, and they are not things that magically turn people into "enlightened beings of endless compassion."

Why do so many meditators want to silence this neuroscientist? - Scott Carney

#discoveries #psychology #meditation

"In theory, at least according to quantum chromodynamics (our theory of the strong nuclear force), there should be multiple ways to make a bound state of quarks, antiquarks, and/or gluons alone."

"You can have baryons (with 3 quarks each) or antibaryons (with 3 antiquarks each)."

"You can have mesons (with a quark-antiquark pair)."

"You can have exotic states like tetraquarks (2 quarks and 2 antiquarks), pentaquarks (4 quarks and 1 antiquark or 1 quark and 4 antiquarks), or hexaquarks (6 quarks, 3 quarks and 3 antiquarks, or 6 antiquarks), etc."

"Or, you can also have states made of gluons alone -- with no valence quarks or antiquarks -- known as glueballs."

Just to joggle your memory, in the Standard Model, protons and neutrons are made of quarks. Electrons aren't made of quarks -- they aren't made of anything, they're their own elementary particle. Particles made of quarks are called hadrons. There's this big machine called the Large Hadron Collider (maybe you have heard of it?) that collides hadrons together -- usually protons, because they are easy to accelerate with magnetic fields. Protons and neutrons are also baryons, which appears in the list above, which have 3 quarks and combine in certain ways dictated by "quantum numbers".

This raises the question of what glues quarks together into larger particles? The Standard Model answer is another particle -- gluons. Gluons carry the so-called "strong force". The subfield of physics for studying the interactions of quarks and gluons is called quantum chromodynamics, because for some reason, physicists decided to name properties of quarks that govern how they interact "color", even though this has nothing to do with actual color, the kind you see with your eyes, because quarks are vastly smaller than the smallest wavelength of light that your eyes can see and therefore don't have any color. (The smallest wavelength of light your eyes can see is about 400 nanometers. The diameter of a proton is about 0.84 femtometers. Remember, your metric prefixes go milli-, micro-, nano-, pico-, femto-, each 1000x smaller than the previous. So protons are about 470 million times smaller than the smallest wavelength of light your eyes can see. As protons are made of quarks, quarks must be smaller still.) They called other properties of quarks "flavors". If you haven't realized by now scientists give weird names to everything, maybe now is the time.

Anyway, based on this, you might not think it's possible to make a particle composed only of gluons. But not only is that what these physicists are claiming to have spotted, but they came up with the most obvious possible name for it, the "glueball".

This wasn't at the Large Hadron Collider (LHC), though, this was at an electron-positron collider in Beijing known as Beijing Spectrometer III (BES III). ("Positrons" are anti-matter electrons.)

"In a radical new paper just published in the journal Physical Review Letters, the BES III collaboration just announced that an exotic particle, previously identified as the X(2370), may indeed be the lightest glueball predicted by the Standard Model."

The article goes on to describe a technique called "Lattice QCD".

"By treating spacetime as a discrete grid with a very small inherent spacing, we can make predictions for larger-scale phenomena: the confinement of QCD bound states, the conditions under which a quark-gluon plasma should arise, and even a prediction for the masses of various bound states, including not only the proton and neutron, but heavy and exotic bound states as well."

This is not a theory of physics, suggesting that space and matter are discrete on small enough scales -- there is such a theory and the scale is known as the Planck length -- it's another, well, to get from our proton diameter down to the Planck length, we'd need to keep going from femto- down 7 more metric prefixes. Anyway, no, that's not what this is about. The "Lattice" in "Lattice QCD" is a numerical approximation technique. As the spacing between lattice sites approaches zero, this approximation method approaches the values predicted by the QCD theory, which uses continuous rather than discrete mathematics.

New particle at last! Physicists detect the first "glueball"

#discoveries #physics #standardmodel

"Surgeons in Japan have transplanted kidney tissue from one rat fetus to another, while the recipient was still in its mother's womb."

Whoa.

"In their study, Takashi Yokoo, a nephrologist at Jikei University School of Medicine in Tokyo, and his colleagues genetically modified rats to express a green fluorescent protein in their kidneys, so that the tissue could be tracked. They then extracted the green kidney tissue from rat fetuses, and used a tiny needle to insert it under the skin of the backs of 18-day-old rat fetuses developing in their mothers' wombs. The rat pups were born after the normal gestation period of around 22 days."

"The tissue gradually developed, forming waste-filtering units known as glomeruli and well-divided inner and outer kidney structures. Two-and-a-half weeks later, the kidneys began to produce urine. 'The timeline is considered to be almost identical to normal development,' says Yokoo. But because the transplanted kidney was not connected to the ureter, the urine had nowhere to go, so the researchers drained the kidney continuously until the rats were euthanized at around five months of age."

"Of the nine fetuses that underwent surgical transplants in four pregnant rats, eight developed fluorescent-green kidneys. In the ninth fetus, the transplanted tissue probably did not embed successfully."

"A close look at the kidneys revealed that the fetuses' blood vessels had grown inside the donated tissue, which made them less likely to be rejected by the immune system. A major cause of organ-transplant rejection is incompatibility between donor blood vessels and the host's body."

First fetus-to-fetus transplant demonstrated in rats

#discoveries #organtransplants

"Two lifeforms merge in once-in-a-billion-years evolutionary event."

"Last time this happened, Earth got plants."

"The phenomenon is called primary endosymbiosis, and it occurs when one microbial organism engulfs another, and starts using it like an internal organ."

The article says the first time was 2.2 billion years ago when mitochondria went from free-standing bacteria to internal organelles of archaea, eventually to become the mitochondria in animals and in us, and the second time was 1.6 billion years ago when free-standing cyanobacteria became organelles of plants called chloroplasts. This time we have a cyanobacterium called UCYN-A that can do nitrogen fixation becoming an organelle of a species of algae called B. bigelowii

What mitochondria do is take energy in the form of sugar (glucose) or ketones derived from fat and turn it into ATP (adenosine triphosphate), which is the chemical form it needs to be in to power the activity of the cell.

What chloroplasts do is photosynthesis, turning sunlight into the energy-storage molecule glucose.

What nitrogen "fixation" is all about -- strange term, I know -- it doesn't mean the nitrogen is "broken", it means the nitrogen is unavailable to biological systems before it gets "fixed" -- don't ask me why people use this term -- is converting atmospheric nitrogen (N2) to a form biological organisms can use. You see, the air we breathe is about 70% nitrogen, but these N2 molecules have a triple bond that is hard to break, so atmospheric N2 basically doesn't react with anything. You breath it in, you breathe it out, nothing happens. You get the nitrogen you need for your cells elsewhere.

And biological cells do need nitrogen. It's a key element in amino acids, the building blocks of protein. It's also part of nucleic acids -- DNA and RNA. You get yours from your food, primarily from the protein. But where does your food get it? It has to come from the atmosphere somewhere along the line. There has to be something analogous to how chloroplasts pull CO2 out of the atmosphere and use it to make glucose.

To get bioavailable nitrogen, cyanobacteria with special cells and enzymes convert atmospheric nitrogen to ammonia (NH4). (Equation below -- I'm going to skip here.) The special enzymes are an enzyme complex called the "nitrogenase complex". The special cells are called heterocysts. The reason the special cells are necessary is the nitrogenase complex enzymes don't work in the presence of oxygen. Heterocysts have extra thick cell walls to keep oxygen out.

The simple way to think of this is as an exchange of N (nitrogen) for C (carbon): The cyanobacteria provides the N and the algae provides the C. The two do an exchange as a symbiotic relationship. And apparently they've taken the next step and merged into a single organism, rather than remaining free-standing symbionts.

Now, the researchers here have not proven unequivocally that such a merger has happened -- for that they would need to prove gene migration between the two organisms. That may be done in time. For now, they have provide pretty compelling evidence: size ratios and synchronized cell division. The article talks about size ratios and that's because the sizes of the two organisms usually move in lockstep after they merge. They show a tight coupling for three sublineages of UCYN-A (called UCYN-A1, UCYN-A2, and UCYN-A3). This makes sense when you consider both want to optimize the underlying metabolic interconnection.

They've also synchronized their cell division, so they reproduce in lockstep. Another hallmark of endosymbiotic merger.

Two lifeforms merge in once-in-a-billion-years evolutionary event

#discoveries #biology #chemistry

"In a series of painstakingly precise experiments, a team of researchers at MIT has demonstrated that heat isn't alone in causing water to evaporate. Light, striking the water's surface where air and water meet, can break water molecules away and float them into the air, causing evaporation in the absence of any source of heat."

"The effect is strongest when light hits the water surface at an angle of 45 degrees. It is also strongest with a certain type of polarization, called transverse magnetic polarization. And it peaks in green light -- which, oddly, is the color for which water is most transparent and thus interacts the least."

They go on to say:

"The astonishing new discovery could help explain mysterious measurements over the years of how sunlight affects clouds, and therefore affect calculations of the effects of climate change on cloud cover and precipitation. It could also lead to new ways of designing industrial processes such as solar-powered desalination or drying of materials."

Does this effect from barely-absorbed visible light really have enough energy for high-performance water desalination driven by solar energy? The paper is paywalled so I guess I'll have to take them at their word.

How light can vaporize water without the need for heat

#discoveries #chemistry #evaporation

Plastics. We think so much about the exponential growth of computer technology that we forget about other things growing exponentially.

It's like that line from the 1967 movie, "I just want to say one word to you... just one word: Plastics."

We may be paying more attention to computers, but plastics haven't gone away. They've kept growing exponentially.

I'm going to quote a boatload of stuff from this PlastChem report, but, in actuality it's going to look like a lot but in reality it's about 2 pages from an 87-page report. Actually once you add in all the appendices it's a 181-page report. And I'm going to quote these parts rather than summarize because I can't think of a way to compress this down much further, so since I can't do a better job of it myself I'm just going to present the choice quotes from the report. Here we go:

"The plastics economy is one of the largest worldwide. The global plastic market was valued at 593 billion USD in 2021. In the same year, the global trade value of plastic products was 1.2 trillion USD or 369 million metric tons, China, the USA, and European states are the major plastic-producing countries with emerging economies experiencing a rapid expansion of local production capacities. The plastics economy is tightly embedded in the petrochemical sector, consuming 90% of its outputs to make plastics. This, in turn, creates strong linkages with the fossil industry, as 99% of plastic is derived from fossil carbon, production mostly relies on fossil energy, and the plastic and fossil industries are economically and infrastructurally integrated."

"Plastic production increases exponentially. The global production of plastics has doubled from 234 million tons in 2000 to 460 million tons in 2019 and its demand grows faster that cement and steel. On average, production grew by 8.5% per year from 1950-2019. Business-as-usual scenarios project that plastic production will triple from 2019 to 2060 with a growth rate of 2.5-4.6% per year, reaching 1230 million tons in 2060. By 2060, 40 billion tons of plastic will have been produced, with about 6 billion tons currently present on Earth."

"The projected increase in plastic use is driven by economic growth and digitalization across regions and sectors. China is expected to remain the largest plastic user, but plastic demand is expected to grow stronger in fast-growing regions, such as Sub-Saharan Africa, India, and other Asian countries. Plastic use is projected to increase substantially across all sectors until 2060, and polymer types used in applications for packaging, construction and transportation make up the largest share of the projected growth.14 Importantly, the OECD predicts that petroleumbased, non-recycled plastics will continue to dominate the market in 2060. Single-use plastics, currently 35-40% of global production, are expected to grow despite regional phase-outs."

"Globally, seven commodity polymers dominate the plastics market. These include polypropylene (PP, 19% of global production), low-density polyethylene (LDPE, 14%), polyvinylchloride (PVC, 13%), high-density polyethylene (HDPE, 13%), polyethylene terephthalate (PET, 6%), polyurethane (PUR, 6%), and polystyrene (PS, 5%). Over 80% of Europe's total polymer demand is met by these, mostly in virgin form). Their usage varies by sector, with HDPE, LDPE, PET, and PP mainly being applied for packaging, and PS and PVC in construction."

"Plastic waste generation is expected to almost triple by 2060. In line with the growth in plastic use, the future plastic waste generation is projected to almost triple, reaching 1014 million tons in 2060. Waste generated from short-lived applications, including packaging, consumer products and textiles, and plastic used in construction are expected to dominate. The latter is relevant because long-lived applications will continue to produce 'locked-in' plastic waste well into the next century. Despite some improvements in waste management and recycling, the OECD projects that the amount of mismanaged plastic waste will continue to grow substantially and almost double to 153 million tons by 2060."

"The scale of plastic pollution is immense. The OECD estimates that 22 million tons of plastic were emitted to the environment in 2019 alone.14 While there are uncertainties in these estimates, they illustrate the substantial leakage of plastics into nature. Accordingly, approximately 140 million tons of plastic have accumulated in aquatic ecosystems until 2019. Emissions to terrestrial systems amount to 13 million tons per year (2019), but the accumulating stocks remain unquantified due to data gaps. While mismanaged waste contributes 82% to these plastic emissions, substantial leakages originate further upstream and throughout the plastic life cycle, such as from the release of micro- and nanoplastics. While the latter represent a relatively small share in terms of tonnage, the number of these particles outsizes that of larger plastic items emitted to nature."

"Plastic pollution is projected to triple in 2060. A business-as-usual scenario with some improvement in waste management and recycling predicts that the annual plastic emissions will double to 44 million tons in 2060. This is in line with other projections which estimate annual emissions of 53-90 million tons by 2030 and 34-55 million tons by 2040 to aquatic environments. According to the OECD, the accumulated stocks of plastics in nature would more than triple in 2060 to an estimated amount of 493 million tons, including the marine environment (145 million tons, 5-fold increase) and freshwater ecosystems (348 million tons, 3-fold increase). Since the impacts of plastic pollution are diverse and occur across the life cycle of plastics, the OECD concludes that 'plastic leakage is a major environmental problem and is getting worse over time. The urgency with which policymakers and other societal decision makers must act is high.'"

"Plastic monomers (e.g., ethylene, propylene, styrene) are mainly derived from fossil resources and then reacted (or, polymerized) to produce polymers (e.g., polyethylene, polypropylene, and polystyrene) that form the backbone of a plastic material. A mixture of starting substances (i.e., monomers, catalysts, and processing aids) is typically used in polymerization reactions. To produce plastic materials, other chemicals, such as stabilizers, are then added. This creates the so-called bulk polymer, usually in the form of pre-production pellets or powders. The bulk polymer is then processed into plastic products by compounding and forming steps, like extrusion and blow molding. Again, other chemicals are added to achieve the desired properties of plastic products, in particular additives. Importantly, such additives were crucial to create marketable materials in the initial development of plastics, and a considerable scientific effort was needed to stabilize early plastics. Throughout this process, processing aids are used to facilitate the production of plastics."

"At the dawn of the plastic age, scientists were unaware of the toxicological and environmental impacts of using additives in plastics. Their work to make plastic durable is essentially what has made plastics both highly useful, but also persistent and toxic."

"The growth in additives production mirrors that of plastics. The amount of additives in plastics can significantly vary, ranging from 0.05-70% of the plastic weight. For example, antioxidants in PE, PS, and ABS (acrylonitrile butadiene styrene) account for 0.5-3% of their weight. Light/UV stabilizers in PE, PP, and PVC constitute 0.1-10% by weight. Flame retardants can make up 2-28% of the weight, while plasticizers in PVC can be as high as 70% by weight. About 6 million tons of additives have been produced in 2016 and the annual growth rate is 4% in the additives sector. Accordingly, additive production can be expected to increase by 130-280 thousand tons per year. By 2060, the joint production volume of a range of additive classes is the projected to increase by a factor of five, closely mirroring the growth in overall plastic production."

"Plastics also contain non-intentionally added substances. Non-intentionally added substances include impurities, degradation products, or compounds formed during the manufacturing process of plastics, which are not deliberately included in the material. Examples include degradation products of known additives (e.g., alkylphenols from antioxidants) and polymers (e.g., styrene oligomers derived from polystyrene). Unlike intentionally added substances (IAS), which are in principle known and therefore can be assessed and regulated, non-intentionally added substances are often complex and unpredictable. Thus, their identity remains mostly unknown and these compounds, though present in and released from all plastics, cannot easily be analyzed, assessed, and regulated. Despite these knowledge gaps, non-intentionally added substances probably represent a major fraction of plastic chemicals."

"The number and diversity of known plastic chemicals is immense. A recent analysis by the United Nations Environment Programme suggests that there are more than 13 000 known plastic chemicals, including polymers, starting substances, processing aids, additives, and non-intentionally added substances. The main reason for such chemical complexity of plastics is the highly fragmented nature of plastic value chains that market almost 100 000 plastic formulations and more than 30 000 additives, 16,000 pigments, and 8000 monomers. While this represents the number of commercially available constituents of plastics, not necessarily the number of unique plastic chemicals, it highlights that the diversity of the plastics sector creates substantial complexity in terms of plastic chemicals."

"A full overview of which chemicals are present in and released from plastics is missing, mostly due to a lack of transparency and publicly available data. Nonetheless, the available scientific evidence demonstrates that most plastic chemicals that have been studied are indeed released from plastic materials and products via migration into liquids and solids (e.g., water, food, soils) and volatilization into air. Additional chemical emissions occur during feedstock extraction and plastic production as well as at the end-of-life (e.g., during incineration). This is problematic because upon release, these chemicals can contaminate natural and human environments which, in turn, results in an exposure of biota and humans."

"Most plastic chemicals can be released. The release of chemicals from plastics has been documented in a multitude of studies, especially in plastic food contact materials, that is, plastics used to store, process or package food. A systematic assessment of 470 scientific studies on plastic food packaging indicates that 1086 out of 1346 analyzed chemicals can migrate into food or food simulants under certain conditions. Accordingly, 81% of the investigated plastic chemicals are highly relevant for human exposure. Newer research with advanced methods to study previously unknown plastic chemicals illustrates that this probably represents the tip of the iceberg. Studies using so-called nontargeted or suspect screening approaches show that commonly more than 2000 chemicals leach from a single plastic product into water. While less information is available on non-food plastics, this highlights two important issues. Firstly, plastics can release a large number of chemicals which, secondly, then become relevant for the exposure of biota, including humans (termed 'exposure potential' in this report)."

"Many plastic chemicals are present in the environment. Upon release, plastic chemicals can enter the environment at every stage of the plastic life cycle. Accordingly, plastic chemicals are ubiquitous in the environment due to the global dispersal of plastic materials, products, waste, and debris. For instance, a recent meta-analysis suggests that more than 800 plastic chemicals have been analyzed in the environment. However, this evidence is fragmented, and a systematic assessment of which compounds have been detected in the environment is lacking. Yet, the evidence on well-studied plastic chemicals indicates that these are present in various environments and biota across the globe, including remote areas far away from known sources. Examples include many phthalates, organophosphate esters, bisphenols, novel brominated flame retardants, and benzotriazoles. Based on the existing evidence on well-researched compounds, it is prudent to assume that many more plastic chemicals are omnipresent in the natural and human environment, including in wildlife and humans."

"Humans are exposed to plastic chemicals across the entire life cycle of plastics. This ranges from the industrial emissions during production, affecting fence line communities, to the releases during use, affecting consumers, and at the end-of-life, including waste handling and incineration. These releases have resulted in extensive exposures of humans to plastic chemicals. For example, many phthalates, bisphenols, benzophenones, parabens, phenolic antioxidants as well as legacy brominated and organophosphate flame retardants have been detected in human blood, urine, and tissues in different global regions. Humans can be exposed to plastic chemicals directly, such as phthalates and other additives leaching from PVC blood bags used for transfusion or leaching into saliva in children mouthing plastic toys. Indirect exposure occurs through the ingestion of contaminated water and foodstuffs that have been in contact with plastics (e.g., processing, packaging). The inhalation and ingestion of plastic chemicals from air, dust and other particulate matter are other important routes of exposure. Importantly, research shows that women, children, and people in underprivileged communities often have higher levels of exposure."

"Non-human organisms are exposed to plastic chemicals. The scientific literature provides rich information on the exposure of wildlife to plastic chemicals, in particular on bisphenols and phthalates in terrestrial and aquatic ecosystems as well as persistent organic pollutants, and antioxidants in marine environments. The United Nations Environment Programme highlights a global biomonitoring study which showed that seabirds from all major oceans contain significant levels of brominated flame retardants and UV stabilizers, indicating widespread contamination even in remote areas. Beyond seabirds, various other species are exposed to plastic chemicals according to the United Nations Environment Programme, such as mussels and fish containing with high levels of hazardous chemicals like HBCDD (hexabromocyclododecane), bisphenol A, and PBDEs (polybrominated diphenyl ethers), suggesting plastics as a probable source. Land animals, including livestock, are exposed to chemicals from plastics, such as PBDEs in poultry and cattle. and phthalates in insects. Importantly, plastic chemicals can also accumulate plants, including those for human consumption. This highlights a significant cross-environmental exposure that spans from marine to terrestrial ecosystems and food systems. However, while research on plastic chemical in non-human biota is abundant, it remains fragmented and has not been systematically compiled and assesses thus far."

"Endocrine disrupting chemicals in plastics represent a major concern for human health. The plastic chemicals nonylphenol and bisphenol A were among the earliest identified compounds that interfere with the normal functioning of hormone systems. These findings marked the beginning of a broader recognition of the role of plastic chemicals in endocrine disruption and dozens have since been identified as endocrine disrupting chemicals. This includes several other bisphenols, phthalates (used as plasticizers), benzophenones (UV filters), and certain phenolic antioxidants, such as 2,4-ditertbutylphenol. For example, strong scientific evidence links bisphenols to cardiovascular diseases, diabetes, and obesity. Accordingly, there is a strong interconnection between plastic chemicals and endocrine disruption."

"Additional groups of plastic chemicals emerge as health concern. The Minderoo-Monaco Commission's recent report comprehensively assesses the health effects of plastics across the life cycle, including plastic chemicals. In addition to phthalates and bisphenols, the report highlights per- and polyfluoroalkyl substances (PFAS) widely utilized for their non-stick and water-repellent properties. PFAS are strongly associated with an increased risk of cancer, thyroid disease, and immune system effects, including reduced vaccine efficacy in children. Additional concerns pertain to their persistence and their tendency to bioaccumulate in humans. In addition, brominated and organophosphate flame retardants have been linked to neurodevelopmental effects and endocrine disruption, adversely affecting cognitive function and behavior in children, as well as thyroid and reproductive health. Several other plastic chemicals are known to cause harm to human health, for example because they are mutagens (e.g., formaldehyde) or carcinogens with other modes of action, like melamine."

"Plastic chemicals also impact human health when released from production and disposal sites. These more indirect effects include the contribution of plastic chemicals to water and air pollution across the life cycle. For instance, chlorofluorocarbons, previously used as blowing agents in plastic production, can deplete the stratospheric ozone layer and thereby indirectly affect human health. Other issues include the promotion of antimicrobial resistance due to the dispersion of biocides transferring from plastics in the environment and the release of dioxins and PCBs from the uncontrolled burning of plastic wastes. The latter are especially toxic and persistent, and accumulate in the food chain, leading to increased human exposure."

"The health impacts of well-researched plastic chemicals are established. Arguably, there is a large body of evidence that links certain groups of plastic chemicals to a range of adverse health effects. These include but is not limited to bisphenols, phthalates, PFAS, and brominated and organophosphate flame retardants. Research focusses particularly on their endocrine disrupting effects, include adverse impacts on reproduction, development, metabolism, and cognitive function. However, it should be noted that research into other groups of plastic chemicals and other types of health effects remains largely fragmented and has rarely been systematically assessed. Here, initiatives such as the Plastic Health Map75 can support a more strategic approach."

"Plastic chemicals exert a host of adverse impacts on wildlife. This includes both acute and chronic toxicity in individual organisms and populations, as well as indirect effects across food webs. Ecotoxicological effects of heavy metals, such as cadmium and lead, as well as endocrine disrupting chemicals used in plastics, such as bisphenols, phthalates, and brominated flame retardants, have received the most research attention to date. Oftentimes, these endocrine disrupting chemicals induce environmental impacts at very low concentrations."

Jumping to page 24 for "Key Findings" of Part II of the report, "What is known about plastic chemicals":

"There are at least 16,000 known plastic chemicals. The report identifies 16,325 compounds that are potentially used or unintentionally present in plastics."

"There is a global governance gap on plastic chemicals. 6% of all compounds are regulated internationally and there is no specific policy instrument for chemicals in plastics."

"Plastic chemicals are produced in volumes of over 9 billion tons per year. Almost 4000 compounds are high-production volume chemicals, each produced at more than 1000 tons per year."

"At least 6300 plastic chemicals have a high exposure potential. These compounds have evidence for their use or presence in plastics, including over 1500 compounds that are known to be released from plastic materials and products."

"Plastic chemicals are very diverse and serve multiple functions. In addition to well-known additives, such as plasticizers and antioxidants, many plastic chemicals often serve multiple functions, for instance, as colorants, processing aids, and fillers."

"Grouping of plastic chemicals based on their structures is feasible. Over 10,000 plastic chemicals are assigned to groups, including large groups of polymers, halogenated compounds, and organophosphates."

Jumping to page 28, they have a visualization of the number of different plastic chemicals by use category:

3674 Colorants
3028 Processing aids
1836 Fillers
1741 Intermediates
1687 Lubricants
1252 Biocides
959 Monomers
897 Crosslinkers
883 Plasticizers
862 Stabilizers
843 Odor agents
764 Light stabilizers
723 Catalysts
595 Antioxidants
478 Initiators
389 Flame retardants
215 Heat stabilizers
205 Antistatic agents
128 Viscosity modifiers
103 Blowing agents
83 Solvents
74 Other additives
56 NIASs (non-intentionally added substances)
47 Others
31 Impact modifiers

On page 30 they have a table that gives you numbers by chemical category (with many groups missing because apparently there is a "long tail" of categories with fewer than 10 members that they didn't bother to include):

802 Alkenes
443 Silanes, siloxanes, silicones
440 PFAS (per- and polyfluoroalkyl substances)
376 Alkanes
202 Carboxylic acids salts
140 PCBs (polychlorinated biphenyls)
124 Aldehydes simple
89 Azodyes
75 Dioxines and furans
66 Alkylphenols
61 Ortho-phthalates
52 Aceto- and benzophenones
50 Phenolic antioxidants
45 PAHs (polycyclic aromatic hydrocarbons)
34 Bisphenols
29 Iso/terephthalates and trimellitates
28 Benzotriazoles
25 Ketones simple
24 Benzothiazole
22 Aromatic amines
20 Alkynes
20 Alkane ethers
18 Chlorinated paraffins combined
15 Aliphatic ketones
14 Aliphatic primary amides
11 Salicylate esters
10 Parabens
10 Aromatic ethers

Page 57 has a table of the number of chemicals by category considered hazardous. Page 61 has a table of the number of chemicals considered hazardous by usage category instead of chemical structure.

Last section is policy recommendations.

The report is 87 pages, but the document is 181 pages. The rest is a series of appendices, which they call the "Annex", which has the glossary, abbreviations, and detailed findings for everything summarized in the rest of the report.

https://plastchem-project.org/

#discoveries #chemistry #health #environment

"Prickly paddy melon weed enzymes show potential as sustainable cement alternative." "An invasive weed that has long plagued the Australian agricultural industry could become a game-changing economic crop due to its potential to produce a cement alternative. Prickly paddy melon costs the agricultural industry around $100 million a year in lost grain yields, cattle deaths and control measures."

"But now researchers say enzymes produced by the paddy melon could be used to create a more sustainable form of cement and prevent soil erosion."

It took me a while to figure out what this was about. What it's about is a type of enzymes called urease enzymes. The reaction urease enzymes catalyze is urea + water = ammonia + carbon dioxide. What this has to do with concrete is there's this concept in concrete of "self healing" concrete, which works (to a limited extent) by having enzymes in the concrete that, when combined with water, precipitate calcium carbonate. Astute observers amoung you will at this point point out that calcium carbonate is not part of the chemical reaction that urease enzymes catalyze. Obviously you also need calcium present to precipitate calcium carbonate, but the real key is that the ph level is changed (more specifically increased, more specifically by the ammonia) such that dissolved calcium ions in the concrete will react with the carbon dioxide to precipitate calcium carbonate.

For those of you who like chemical formulas (helps me understand what's going on but I hear some people are scared off by formulas) , the reaction that the urease enzymes catalyze is:

(NH2)2CO + H2O -> 2NH3 + CO2

(that is, two of the (NH2) groups -- the lack of subscripts can be confusing).

And the formula for calcium carbonate is CaCO3.

What does all this have to do with the Australian weed prickly paddy melon? Apparently it's possible to produce these urease enzymes in massive quantities by extracting them from this plant.

I was disappointed by this as we humans consume crazy amounts of sand and are depleting the planet of sand for use in concrete, and I was hoping this would help with that. But no. In fact if you chase down the actual research paper (or the abstract, the full paper is paywalled), you'll find the researchers were primarily interested in urease enzymes for soil. Since ammonia increases pH, if a soil is acidic (remember, pH numbers under 7.0 are acidic, the lower the more acidic, while pH numbers above 7.0 are basic/alkaline, the higher the more basic/alkaline), adding these enzymes can reduce the acidity. Since ammonia is a nitrogen compound, it also helps to make nitrogen available for crops.

So, this won't help with concrete production from sand, and the article doesn't even try but instead talks about carbon footprint. Might be useful for limited "self-healing" concrete, and probably most useful for agricultural crop soil.

Prickly paddy melon weed enzymes show potential as sustainable cement alternative

#discoveries #chemistry #agriculture

How "top heavy" is YouTube? 65% of videos have fewer than 100 views. 87% have fewer than 1,000 views. Only 3.7% of videos exceed 10,000 views, which is the threshold for monetization. Those 3.7% of views get 94% of views. The top 0.16% of videos get 50% of video views.

In other words, video views on YouTube follow a power law distribution, as you might have expected, but it's a lot steeper than you might have expected.

How was this figured out? Using a new but simple technique called "dialing for videos".

You may not realize it, but those YouTube IDs that look like a jumble of letters and numbers, like "A-SyeJaMMjI", are actually numbers. Yes, all YouTube video IDs are actually numbers. They're just not written in base 10. They're 64-bit numbers written in base 64. If you're wondering how YouTube came up with 64 digits, think about it: digits 0-9 give you 10, then lower case letters a-z give you 26 more, bringing you up to 36, then uppercase letters A-Z give you 26 more, getting you up to 62. You still need 2 more for that, and YouTube chose the dash ("-") and the underscore ("_").

Because the numbers are randomly chosen 64-bit numbers, there are 2^64 possibilities, which in decimal is 18,446,744,073,709,551,616. That's much too large to try every number or even numbers at random. But the researchers discovered a quirk. Through the YouTube API they could do searches, and YouTube would do the search in a case-insensitive way. Well, except not for the last character for some reason. And it would allow 32 IDs to be searched on in the same query. So the researchers were about to find 10,000 videos (well, 10,016 actually) by doing millions of searchers. This collection of 10,000 videos is likely to be more representative of all of YouTube than any other sample academic researchers have ever hard. All previous attempts have resulted in biased results because they were influenced either by the recommendation system, personalized search results, or just whatever secret algorithms YouTube has that determines how it ranks videos that it enables you to find.

How big is YouTube? Their estimate is 9.8 billion videos. Or at least that's how big it was between October 5, 2022, and December 13, 2022, which is when they did their data collection. Their paper was finally published last December.

By looking at what percentage of their sample were uploaded in any given year, they can chart the growth of YouTube:

Year - Percentage of sample
2005 - 0.00%
2006 - 0.05%
2007 - 0.22%
2008 - 0.43%
2009 - 0.74%
2010 - 1.13%
2011 - 1.67%
2012 - 1.86%
2013 - 1.97%
2014 - 2.34%
2015 - 3.02%
2016 - 4.25%
2017 - 5.39%
2018 - 6.73%
2019 - 8.81%
2020 - 15.22%
2021 - 20.29%
2022 - 25.91%

Translating those numbers into millions of videos (remember, a thousand million is a billion), we get this list:

2005 - 0
2006 - 5
2007 - 27
2008 - 69
2009 - 142
2010 - 254
2011 - 418
2012 - 602
2013 - 796
2014 - 1,072
2015 - 1,325
2016 - 1,745
2017 - 2,278
2018 - 2,943
2019 - 3,813
2020 - 5,316
2021 - 7,321
2022 - 9,881

73% of videos had no comments. 1.04% of videos had 100 comments or more, and those accounted for 55% of all comments in the sample.

"Likes" are evn more skewed, with 0.08% of videos getting 55% of likes.

YouTube disabled the "Dislike" buttons in 2021.

Most channels had at least one subscriber and the average was 65. Subscriber counts, while less "top heavy", turned out to be weakly correlated with views. The researchers estimate 70% of views of any given video come from algorithms and not from subscribers or external links pointing to a video.

Median video length was 615 seconds (10 minutes, 15 seconds). 6.2% were 10 seconds or less, 38% were 1 minute or less, 82% were ten minutes or less, and only 3.9% were an hour or more.

Words that occurred most in metadata tags included "Sony" and "Playstation".

The researchers employed hand-coders to hand-code a subsample of 1,000 videos. They found only 3% of videos had anything to do with news, politics, or current events. 3.8% had anything to do with religion. 15.5% had just still images for the video part. (I actually see a lot of music videos like this -- just an album cover or photo of the artist and the rest is audio.). 19.5% were streams of video games. 8.4 was computer-generated but not a video game. 14.3% had a background design indicating they were produced on some sort of set. 84.3% were edited. 36.7% had text or graphics overlaid on the video. 35.7% was recorded indoors. 18.1% was recorded outdoors. (The remainder were both or unclear.) Cameras were "shaky" 52.3% of the time. A human was seen talking to the camera 18.3% of the time. 9.1% of videos recorded a public event. The video was something obviously not owned by the uploader, such as a movie clip, 4.8% of the time.

Sponsorships and "calls to action" were only present in 3.8% of videos.

96.8% of videos had audio. 40.5% were deemed by coders to be entirely or almost entirely music. Many of these were backgrounds for performances, video game footage, or slide shows.

53.8% had spoken language. 28.9% had spoken language on top of music.

For languages, "we built our own language detection pipeline by running each video's audio file using the VoxLingua107 ECAPA-TDNN spoken language recognition model."

Language distribution was:

English: 20.1%
Hindi: 7.6%
Spanish: 6.2%
Welsh: 5.7%
Portuguese: 4.9%
Latin: 4.6%
Russian: 4.2%
Arabic: 3.3%
Javanese: 3.3%
Waray: 3.2%
Japanese: 2.2%
Indonesian: 2.0%
French: 1.8%
Icelandic: 1.7%
Urdu: 1.5%
Sindhi: 1.4%
Bengali: 1.4%
Thai: 1.2%
Turkish: 1.2%
Central Khumer: 1.1%

"It is unlikely that Welsh is the fourth most common language on YouTube, for example, or that Icelandic is spoken more often than Urdu, Bengali, or Turkish. More startling still is that, according to this analysis Latin is not a 'dead language' but rather the sixth most common language spoken on YouTube. Of the top 20, Welsh, Latin, Waray-Waray, and Icelandic are not in the top 200 most spoken languages, and Sindhi and Central Khmer are not in the top 50 (Ethnologue, 2022). The VoxLingua107 documentation notes a number of languages which are commonly mistaken for another (Urdu for Hindi, Spanish for Galician, Norwegian for Nynorsk, Dutch for Afrikaans, English for Welsh, and Estonian for Finnish), but does not account for the other unusual results we have seen. We thought that some of the errors may be because of the amount of music in our sample, but removing the videos that are part of YouTube Music (which does not include all music) did not yield significantly different results."

"It is worth highlighting just how many of the most popular languages are not among the languages available in the YouTube autocaptioning system: Hindi, Arabic, Javanese, Waray-Waray, Urdu, Thai, Bengali, and Sindhi."

Dialing for videos: A random sample of YouTube

#solidstatelife #discoveries #winnertakeall #powerlawdistribution #youtube

"Attention deficits linked with proclivity to explore while foraging".

"Our findings suggest that ADHD attributes may confer foraging advantages in some environments and invite the possibility that this condition may reflect an adaptation favouring exploration over exploitation."

I first encountered the "exploration over exploitation" in the context of reinforcement learning in computer science. The basic idea is, should you go to your favorite restaurant, or a restaurant you've never been to before? If you're in a new city where you've been to few restaurants, you should probably go to a new one. If you're in a city where you've lived for 10 years, and have been to most restaurants, maybe just go to the favorite. Where is the crossover point in between? You get the idea. Do you "exploit" the knowledge you have already, or do you "explore" to obtain more knowledge?

For the simplest cases, mathematicians have come up with formulas, and for complex cases, computer scientists have run simulations. In reinforcement learning, algorithms often have a tunable "hyperparameter" that can be used to increase the "exploration". Some problems require more "exploration" than others.

It appears the process of evolution may have evolved a variety of personalities to prioritize "exploration" or "exploitation".

Attention deficits linked with proclivity to explore while foraging

#discoveries #psychology #evolution