Saturday, July 29, 2023

I finally understand carbon dating.

From the La Brea tar pits museum in L.A. -

Radiocarbon Dating

At this moment, as in the past, a relatively constant amount of radioactive carbon, or carbon-14, is formed in the upper atmosphere by cosmic ray bombardment of nitrogen (14N). As the carbon-14 spreads through the atmosphere, it combines with oxygen (O), forming carbon dioxide (CO2) which is eventually absorbed by plants. Plant eaters ingest the carbon-14 and it is eventually passed up the food chain to the carnivores. When they die, no new carbon-14 is added to their tissues, and the carbon-14 present gradually changes back to nitrogen at a fixed rate. Therefore, the amount of carbon-14 relative to normal carbon tells scientists how long ago an organism died. After 5,730 years, only one-half of the original carbon-14 is present and after about 45,000 years essentially all carbon-14 has reverted back to nitrogen. 

Tuesday, July 25, 2023

Biomimicry in architecture

This video is particularly well researched and illustrated. If you don't have time, you can start watching at 7:47



10:51 "with every new technology that's introduced... they're able to more closely mimic nature's designs, and they're able to better optimize the characteristics of each material leading to stronger and more resource-efficient structures that don't look like anything else that's been built before."

11:34 Neri Oxman's work at MIT, co-creating structures with nature, is also fascinating. 

Sunday, July 23, 2023

Bees actually prefer purple flowers

Bees prefer purple, and their vision is attuned to the violet end of the spectrum.
"In nectar-rich flowers, there are often pigmented patterns on the petals that absorb UV light and create a 'guide' to ferry the bee towards its nectaries. Remember, flowers want to be pollinated so that they can survive and produce offspring, so this UV pigment development is no accident." 

 It's a brilliant example of "co-evolution."
"The two groups have coevolved for mutual success. Adult bees evolved behavioral and physiological adaptations to gather and transport pollen more efficiently...[e.g.] buzz-pollination: flight muscles can create sound vibrations that dislodge pollen from flowers... Many flowers signal pollinators by changing color at different stages of development, attracting pollinators when they need them most, thus increasing the efficiency of the pollinators"


And an interesting co-evolution is the shift, among several species of the same genus, from attracting bees to attracting hummingbirds, which must be even more effective pollinators. These flowers changed their structure in specific ways from attracting bees (blue color, wide corolla, landing platform) to promoting hummingbirds (red color, long thin tubular corolla)

Which came first - flowers or bees? This video answers that. 
https://youtu.be/iyvXZcWUbI0

This hummingbird and its favorite flower co-evolved so the two are uniquely dependent on each other. 
https://youtu.be/7xRxpicxeFQ


Friday, July 21, 2023

Athletic dominance of African Americans

The athletic dominance of African Americans—Is there a genetic basis? 1996 Harpalani

"...1939, Eleanor Metheny...study of physical and athletic performance differences between races... concluded that African Americans surpassed European Americans in...weight, shoulder breadth, chest depth and width, neck and limb girths, and length of arm, forearm, hand, leg, and lower leg. European Americans were higher in sitting height, total fat, and hip width...went on to postulate athletic consequences of her study...physical features of African Americans yielded advantages in various sports. Greater body weight due to heavier bones and more musculature, coupled with lower body fat..."
"African Americans have faster reaction times than do Europeans, on average, although it is unclear whether this effect is inherited or acquired through training (Jordan, 1969, 96). Studies have shown that African Americans dissipate heat more effectively than do European Americans, due to longer limbs and greater quantity of sweat glands."

"African Americans appear to exhibit advanced skeletal and motor development in comparison to European Americans (Malina, 1988)"

"the African American athlete has a greater power-to-weight ratio than does the European American athlete, regardless of the athlete's size. This would yield an advantage in events such as sprints and jumps (Kane 1971)"

"a study that showed Ugandan infants had
 extremely precocious muscular development compared to European infants (Kane, 1971.) Kane also mentions two common hypotheses: slave selection and slave breeding."

"...Edwards offered several criticisms [of Kane.] First, he claimed that the evidence for physical differences between the races was derived from exceptional African American athletes and not from a random sample of the African American population. Second, Edwards noted that anthropologists have not been successful in deriving criteria to divide humans into discrete "races." Third, he pointed out that because of the many complex factors that determine athletics performance, it is difficult to draw any conclusions about such performance based observable variables."

The published historical evidence on the transatlantic slave trade and New World slavery (from the 16th century to the 19th century) reveals that conditions existed for "natural selection," and therefore, genetic changes were virtually inevitable in the slave populations. (Wilson and Grim, 1991)...It is also important to note that Wilson and Grim's work is controversial; other sources claim it is completely invalid."

Norde concluded that...slave breeding was a common practice (Norde, 1985). Moreover,
 the major motive behind slave breeding was profit. Norde noted advertisements for the sale of thousands of female slaves on a daily basis. Many of these advertisements stated that the female slaves were "'good' or 'fine' for breeding..." 

"For argument's sake...a multifactorial trait like speed or any athletic endeavor would probably be normally distributed. The slight advantage may cause a small shift in the African American normal curve, such that the top 0.1 % of individuals on the speed index (i.e., the fastest 0.1 % of the population) would consist almost exclusively of African Americans..."
 
"Slow-twitch (type I, oxidative) muscle fibers contract slowly and are necessary for endurance events (e.g., long-distance run- ning). Fast-twitch (type Ila and lib, oxidative and glycolytic respectively) muscle fibers contract much faster and are necessary for events requiring sudden bursts of energy...46 male subjects, 23 European Canadians and 23 Africans from Cameroon, Senegal, Zaire, Ivory Coast, and Burundi. All subjects were matched for age, weight, height, and body mass index. They were...involved only in sedentary activities at the time of the study... Africans were significantly higher in fast-twitch muscle fiber proportion and area (for both type Ila and lib). Africans also had significantly higher activity levels for glycolytic enzymes hexokinase, phosphofructokinase, lactate dehydrogenase and for the phosphagenic enzyme creatine kinase."

"Is there a genetic basis for the success of African American athletes? The evidence is unclear at this time. Several lines of data seem to point to genetic factors, but these lines do not fit together, and in some cases they even contradict each other. The issue warrants further study before any conclusions can be made..."

Vinay Harpalani
Journal of African American Men, Vol. 2, 1997, pp. 39-56



However, as a counterpoint to this, an editorial from 2018 is relevant. 
"even if African-Americans were genetically [superior]... It is not possible to categorize an entire racial group as being genetically or physiologically distinct from one another because of the vast genetic heterogeneity of our populations."

"...treat African-Americans as a genetically homogenous group...we should reject the premise of genetic determinism and essential black abnormality and not think of racial groups as fundamentally distinct in terms of biology or physiology."


Androgen and survival advantages in African Americans

Another hypothesis on genetic difference in African Americans that offered a survival advantage during the passage from Africa... 

"... slaves possessing more responsive androgen receptors experienced a survival advantage engendered by the enhanced anabolic effects which accrued such as increased red cell mass and therefore greater oxygen carrying capacity and tissue oxygen delivery enabling these slaves to tolerate stifling conditions in the hull of the slave ship..."

"African-Americans having the highest prostate cancer incidence rate and the Caribbean having the highest prostate cancer mortality rates in the world are consistent with this hypothesis as is the observation that the 10 fastest men and 9 fastest women of all time are exclusively the descendants of West African slaves who survived the middle passage." 



However, to quote a related editorial, 
"even if African-Americans were genetically [different]... It is not possible to categorize an entire racial group as being genetically or physiologically distinct from one another because of the vast genetic heterogeneity of our populations."

"Overcoming this bias and refusing to treat African-Americans as a genetically homogenous group is critical for our nation's health because minorities receive less and lower quality healthcare than do Caucasians...we should reject the premise of genetic determinism and essential black abnormality and not think of racial groups as fundamentally distinct in terms of biology or physiology."

https://journals.physiology.org/doi/full/10.1152/advan.00070.2018

The “African gene” theory: it is time to stop teaching and promoting the slavery hypertension hypothesis

This is the perfect medical editorial - taking a simple and oft-repeated widespread medical folk hypothesis and placing it in the broader context and then  going beyond that to expound on the dangers of biases that should be eradicated in medicine and society in general. 
Myth: "African-Americans today are afflicted by hypertension at higher rate than whites because of genes passed on by their ancestors, genes that favored salt retention and that, in turn, cause high blood pressure... [slaves were] subjected to limited water and salt supplies and bouts of dehydration. As a result, a genetic predisposition for salt retention evolved in individuals of African descent. A higher sodium-retention mechanism enhanced survival during these extreme weather conditions, but the same mechanism would lead to hypertension..."

"However, pathophysiological, historical, and anthropological data strongly dispute the hypothesis... the results of sodium balance studies... consistently demonstrate that, in response to salt loading, normal salt-resistant subjects (individuals resistant to the pressor effects of salt) retain just as much sodium as salt-sensitive subjects (individuals with a pressor response to salt). Despite retaining just as much salt as salt-sensitive subjects, salt-resistant subjects do not develop hypertension...even if African-Americans were genetically programmed to conserve more salt (which is highly unlikely), this alone would not elevate their blood pressure. "

"even if African-Americans were genetically programmed to conserve more salt (which is highly unlikely), this alone would not elevate their blood pressure... It is not possible to categorize an entire racial group as being genetically or physiologically distinct from one another because of the vast genetic heterogeneity of our populations."

"Overcoming this bias and refusing to treat African-Americans as a genetically homogenous group is critical for our nation's health because minorities receive less and lower quality healthcare than do Caucasians...we should reject the premise of genetic determinism and essential black abnormality and not think of racial groups as fundamentally distinct in terms of biology or physiology."




Thursday, July 20, 2023

What it takes to buy a Ferrari

Can you believe this? 
You have to cultivate a relationship with your dealer, proving you are genuinely interested in the car by going to rallies and races, before they'll put you in their secret list to buy a car. They obviously don't want people buying a car on spec and selling it as soon as they get it. 

Saturday, July 15, 2023

Does leaving a light on use less energy than turning it off and on?

This myth is not true for fluorescent, and especially not true for LED bulbs.
"The energy consumed to start a typical lamp is the equivalent of 2 seconds running time, so it is wrong to say it takes a lot of power to start them. It is true there is a current surge but this takes place in less than one-eighth of a second and because it happens so quickly it takes very little energy.

It is true that switching on/off fluorescents reduces lamp life but lamps are designed to be switched on/off up to seven times a day without any effect on their life."    https://www.environment.admin.cam.ac.uk/resources/mythbusters-facts-top-tips/fluorescent-myth
"The operating life of a LED is unaffected by turning it on and off. While lifetime is reduced for fluorescent lamps the more often they are switched on and off, there is no negative effect on LED lifetime." 
I'll reluctantly admit that there's an argument for leaving incandescent bulbs on continuously, or starting them gradually each time with a dimmer switch. The in-rush of current can damage and eventually thin the filament leading to failure. 

Wednesday, July 12, 2023

California Duck Curve Getting Deeper With Solar Growth - CleanTechnica



The duck curve is deepening, because solar is generating more mid-day energy, but battery storage of solar energy may help alleviate the evening rise in power demand

Thursday, July 6, 2023

How to Create a Custom Map in Google Sheets

Free mapping extension 
Open a new or existing spreadsheet in Google Sheets.
Go to the Extensions menu and select Add-ons.
Click on Get add-ons. This will open the Google Workplace Marketplace.
In the marketplace, search for Mapping Sheets and click on it.
Click on Install and then allow the necessary permissions.


Make your spreadsheet: Mapping Sheets requires at least three columns of data to function correctly: Name, address or coordinates, and category

Tuesday, July 4, 2023

Pachelbel's Canon in D but it keeps getting jazzier

 

Brilliant!

Saab still lives!

 


Placing the motors inside the wheels frees up a lot of space, 7:32 allowing a "cab-forward" design that's more aerodynamic...lower roofline...mass reduction...more efficient because the motors don't have gears... 

8:10 - leads to a vehicle that is able to transport a unit of volume in a much more efficient manner from A to B, so that means less charging, smaller batteries for a given range, lower cost.

11:32 In-wheel motors were invented by Porsche himself in 1925. [They're also in the Aptera.]

Sunday, July 2, 2023

Tesla repairs eg coolant leak into motor




QC Charge in California repairs Tesla motors - upgrading the seals so coolant doesn't leak into the engine at 100K miles, and upgrading the bearing seals.

Here's how to check for coolant leak:

 

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