Sunday, May 31, 2020
Saturday, May 30, 2020
Anesthesia's mechanism of action discovered
The cell membrane lipid complex GM1 is disrupted, leaks PLD2 which associates with PIP2 which allows TREK1 ion channels to spill potassium out of neurons, shutting down neural transmission.
Friday, May 29, 2020
Trading by playing the psychology of round numbers
Astronauts experienced reversed jugular venous blood flow.
""Reverse flow is really interesting, and we're uncertain if it harmful," Stenger said. "Reverse flow in the jugular vein could be completely harmless as the blood is simply leaving the head via one of the other venous pathways. However, reverse flow implies altered venous pressure dynamics, which could impact the ability of the brain to drain cerebral spinal fluid and possibly increase pressure in the brain."
https://amp.cnn.com/cnn/2019/11/15/health/astronaut-blood-flow-clot-scn-trnd/index.html
Here's the original paper:
Here's the original paper:
Assessment of Jugular Venous Blood Flow Stasis and Thrombosis During Spaceflight
"stagnant or reverse flow in the internal jugular vein was observed in 6 crew members (55%) on approximate flight day 50. Notably, 1 crew member was found to have an occlusive internal jugular vein thrombus, and a potential partial thrombus was identified in another crew member retrospectively."
YouTube algorithm
This podcast goes to a dark place. But along the way, it includes a discussion at about 18 minutes about the algorithm for selecting YouTube videos, and efforts (discouraged by Google) to prevent someone from getting an unbalanced view of hearing only one side of an issue.
Thursday, May 28, 2020
Flocking Birds
(Just the first 8 minutes)
A beautifully elegant description, and demonstration by modeling, of how birds fly in a flock.
1) fly towards the center of all the birds
2) avoid nearby birds
3) match the speed and direction of nearby birds
His "smarter every day" videos are consistently good.
How many nearby birds does each bird align itself with and follow?
How many nearby birds does each bird align itself with and follow?
How many neighboring birds does one bird align itself with in a huge flock?
"Turns out the magic number is seven: Each bird keeps tabs on its seven closest neighbors and ignores all else."
Beautiful murmuration:
https://youtu.be/V4f_1_r80RY
Monday, May 25, 2020
Dating and Relationships in the Digital Age | Pew Research Center
Sunday, May 24, 2020
It’s Time to Rethink America’s Corn System - Scientific American
"Although U.S. corn is a highly productive crop, with typical yields between 140 and 160 bushels per acre, the resulting delivery of food by the corn system is far lower. Today's corn crop is mainly used for biofuels (~40%...) and as animal feed (~36 %, plus distillers grains left over from ethanol production, is fed to cattle, pigs and chickens). Much of the rest is exported. Only a tiny fraction of the national corn crop is directly used for food for Americans, much of that for high-fructose corn syrup."
The rapid pace of computer animation improvements.
I like this fellow's enthusiasm - he always says "what a great time to be alive!" in each video.
Here's another mesmerizing video of simulating viscous fluids and jellies:
And his remorse at missing a paper from 8 years ago that was revolutionarily simple in adding bubbles, foam, and spray to water simulation by searching for acutely angled constrictions in the water-air interface.
@5:50 "One simple, brilliant idea changes everything" in computing depth maps of video footage without the crutch of having to use human input.
What the Tesla autopilot computer "sees"
Thought you'd like this video which shows what the onboard computer sees and interprets from its cameras. There's a lot of object recognition going on.
Thursday, May 21, 2020
How many solar panels to charge your electric car?
"...To consider this question, we'll use the standard Tesla Model S as a baseline for estimates. This Tesla has a battery with a 75-kWh capacity... "The average 250 W solar panel can generate around 30-40 kWh of AC power each month... "since the average driver will travel approximately 37 miles a day – this translates to roughly 12 kWh of electricity. With that in mind, a much more realistic set would require approximately 12 solar panels..."
"for an average American driver, a typical EV will require about 4,000 kWh of electricity per year. According to the most recent EnergySage Solar Marketplace Intel report, the most frequently offered solar panels on EnergySage are in the 320 to 330 Watt range. Finally, the production from your solar panels will vary from region to region...Depending upon where you live, charging an electric vehicle typically requires 7 or 9 solar panels." https://news.energysage.com/how-many-panels-do-you-need-for-your-ev/
Monday, May 18, 2020
IBD improves even when the patient knows they're taking placebo
Placebos have been accepted in science as a means of comparing the effect of doing "nothing" compared to some medication under study. But the effect of the placebo is known to be beneficial - so what happens if you tell the patient that they are getting a placebo? You also empathetically listen and encourage them that they will improve - is that positive interaction able to produce results? The surprising answer is yes.
Here's the actual formal study of placebo effect from knowingly taking placebos.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2832199/
And here's a podcast including an intriguing interview with one of the patients doubting herself but willing to try placebo, and desperately wanting it continued after the trial ended!
https://podcasts.google.com/?feed=aHR0cHM6Ly9mZWVkcy5ucHIub3JnLzUxMDMwOC9wb2RjYXN0LnhtbA&ep=14&episode=ZWZlZmMxZWEtOGQxMy00MzM3LTg4N2ItMzhiYmFmMTI3MmU3
https://www.npr.org/2020/05/11/853753307/all-the-worlds-a-stage-including-the-doctor-s-office
Here's the actual formal study of placebo effect from knowingly taking placebos.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2832199/
And here's a podcast including an intriguing interview with one of the patients doubting herself but willing to try placebo, and desperately wanting it continued after the trial ended!
https://podcasts.google.com/?feed=aHR0cHM6Ly9mZWVkcy5ucHIub3JnLzUxMDMwOC9wb2RjYXN0LnhtbA&ep=14&episode=ZWZlZmMxZWEtOGQxMy00MzM3LTg4N2ItMzhiYmFmMTI3MmU3
https://www.npr.org/2020/05/11/853753307/all-the-worlds-a-stage-including-the-doctor-s-office
Also, here's a freakonomics episode about placebos
https://freakonomics.com/podcast/is-the-placebo-effect-for-real/
Sunday, May 17, 2020
Two young African inventor's stories
https://youtu.be/XOLOLrUBRBY
Where is he now? - Avoidin the medi circus.
"The plan is to complete my current diploma program in Toronto, Canada, apply and hopefully be accepted in the Management Engineering program at the University of Waterloo to learn about data analytics, analysis, evidence-based thinking – things needed in the future if I am to plan, think things through, present cases for funding, support claims, and have successful projects in Sierra Leone.
Unfortunately, the cost of an education for an international student is roughly 60k CDN a year...I now have a mentoring team here in Canada that is focused on turning off the circus, helping me find myself, managing my finances, turning me into a ‘normal’, professional student, and guiding me through this next part of my life. The mentoring team is providing advice, helping me recover…, and some are helping with my schooling costs." https://ktvsl.com/2018/08/13/kelvin-doe-revealed-his-true-story/
https://youtu.be/nPkr9HmglG0
Where is he now?
Right now what I’m working on is to put up an innovation center in Malawi. The innovation center is going to allow people to come and work with me to develop their ideas. Because I know there are so many talented young people all over the world but sometimes lack of space to help them build their ideas, it’s lacking sometimes so I want to enable that, making sure that anyone who has an idea they can have a space where they can think and build and be connected to professionals in the field that they are working on.
https://www.redbull.com/za-en/William-Kamkwamba-on-life-after-harnessing-the-wind
Where is he now?
Right now what I’m working on is to put up an innovation center in Malawi. The innovation center is going to allow people to come and work with me to develop their ideas. Because I know there are so many talented young people all over the world but sometimes lack of space to help them build their ideas, it’s lacking sometimes so I want to enable that, making sure that anyone who has an idea they can have a space where they can think and build and be connected to professionals in the field that they are working on.
https://www.redbull.com/za-en/William-Kamkwamba-on-life-after-harnessing-the-wind
Friday, May 15, 2020
Placebo effect: randomised controlled trial in irritable bowel syndrome
Wednesday, May 13, 2020
Fluid simulations
Less scientific, but equally mesmerizing are these real-life paint splatters in slow motion.
And, if you're not getting tired of slow motion color,
Monday, May 11, 2020
Bluetooth keeps disconnecting on my MAC ( Mojave )
Tried all the fixes listed below, rebooted, and the problem persisted. Fionally tried this approach - disable "Handoff between this MAC and iCloud devices." under System Preferences --> General.
Holding the Shift + Option (Alt) keys on your Mac's keyboard, click the Bluetooth symbol in the top-right corner of the macOS menu bar.* Holding the Shift + Option (Alt) keys on your Mac's keyboard, click the Bluetooth symbol in the top-right corner of the macOS menu bar. (If you don't see it there, you need to check Show Bluetooth in menu bar in System Preferences -> Bluetooth.) Now, restart your Mac.
You'll notice a couple of other potentially useful options in the Debug submenu. Factory reset all connected Apple devices does exactly what it says – forces any Apple-branded Bluetooth accessories back to the default settings they came with out of the box. It's a reliable fallback option if you've tried everything else to fix a connection issue, including resetting the Bluetooth module.
*(If you don't see it there, you need to check Show Bluetooth in menu bar in System Preferences -> Bluetooth.)
Follow-up June 30: the problem persisted despite all the above maneuvers, and taking it for a diagnostic servicing, where (of course) everything worked perfectly, only to reurn as soon as I got home. The problem may ahve been Bluettoth interference from a nearby wifi, or perhaps a neighbor's wifi range extender - I'll never know. But I ended up buying a "wired" keyboard and mouse, which was surprisingly difficult to find these days.
Follow-up June 30: the problem persisted despite all the above maneuvers, and taking it for a diagnostic servicing, where (of course) everything worked perfectly, only to reurn as soon as I got home. The problem may ahve been Bluettoth interference from a nearby wifi, or perhaps a neighbor's wifi range extender - I'll never know. But I ended up buying a "wired" keyboard and mouse, which was surprisingly difficult to find these days.
How long does a COVID-positive patient remain infectious?
I wanted to know how long a patient remains infective after testing COVID positive, given that we are planning on waiting 2 weeks after a positive test before retesting, and given that the second test has a non-negligible false negative rate. Is two weeks long enough? It appears so, as much as we can tell from available data. These data are all right-skewed bell curves, so obviously one can't be precise in giving an exact number of days because of the long skinny "tail" of a bell curve. This was a quick Google search, not a careful review. My comments are in square brackets.
[It's important to distinguish between infectiveness vs. detection of virus. The duration of infectiveness with COVID seems to start 2 days before symptoms and declines rapidly 7 days after symptom onset, even though vital particles are detectable for 21 days after symptom onset: ]
Temporal dynamics in viral shedding and transmissibility of COVID-19. Nature Apr 15, 2020
"We estimated that 44% (95% confidence interval, 25–69%) of secondary cases were infected during the index cases’ presymptomatic stage..."
"serial interval (duration between symptom onsets of successive cases in a transmission chain)...based on 77 transmission pairs obtained from publicly available sources within and outside mainland China...the serial interval was estimated to have a mean of 5.8 days (95% confidence interval (CI), 4.8–6.8 days) and a median of 5.2 days (95% CI, 4.1–6.4 days)...we inferred that infectiousness started from 2.3 days (95% CI, 0.8–3.0 days) before symptom onset and peaked at 0.7 days (95% CI, −0.2–2.0 days) before symptom onset... Infectiousness was estimated to decline quickly within 7 days.
"We detected high viral loads soon after symptom onset, which then gradually decreased towards the detection limit at about day 21."
https://www.nature.com/articles/s41591-020-0869-5#Fig1
[The sensitivity and specificity of COVID PCR testing: In the lab, tests achieve "at least 96 percent specificity on negative samples"
https://spectrum.ieee.org/the-human-os/biomedical/diagnostics/testing-tests-which-covid19-tests-are-most-accurate ]
[But real-world clinical specificity has to do with multiple factors (reaching nasopharynx accurately with the swab, contamination of the specimen, storing and transporting the sample, delays etc.)
https://diagnostics.roche.com/us/en/roche-blog/COVID-19-testing-what-you-need-to-know-about-test-accuracy.html ]
False Negatives and Reinfections: the Challenges of SARS-CoV-2 RT-PCR Testing. Am So Microbiol Apr 27, 2020
"There currently is no gold-standard diagnostic test for SARS-CoV-2 since the virus is new to us."
"NP swabs have on the order of 100,000 (10E5) to 1,000,000 (10E6) cp/mL [viral copies per mL] of viral RNA. Even the less sensitive tests have LODs in the range of 1000s [10E3] of cp/mL, so the levels of RNA in clinical samples during acute infections should be easily detectable."
"...a test with good analytical sensitivity and specificity does not necessarily have good clinical sensitivity and specificity."
"We are learning something new every day about the best specimen types, collection methods and testing platforms for SARS2-CoV detection. These variables could help explain why some SARS-CoV-2 tests are negative when in fact, the patient has clinical disease...RNA is less stable than DNA, so if a specimen is not transported or stored appropriately, the risk of a false-negative RT-PCR result increases."
"peer-reviewed study...demonstrated that the virus was detectable by RT-PCR in patients who survived COVID-19 for up to 37 days, with a median time of 20 days...Lingering positive results are possibly explained if viral RNA remains in tissues for a considerable amount of time, even when the viral particles capable of causing infection have been cleared."
"As yet, there is no consensus on how accurate our testing is, and given the potential for asymptomatic carriage and prolonged viral shedding post-infection, we likely have a long road ahead and many lessons to learn."
https://asm.org/Articles/2020/April/False-Negatives-and-Reinfections-the-Challenges-of
Sunday, May 10, 2020
US mishandled COVID
"...Rudderless, blindsided, lethargic, and uncoordinated, America has mishandled the COVID-19 crisis."
Wednesday, May 6, 2020
Choosing is inventing.
A person who has spent her lifetime researching how we make choices emphasized this quotation - "Invention consists of avoiding the construction of useless combinations, and consists of constructing useful combinations which are an infinite minority. To invent is to discern is to choose"- Henri Poicarre
...So for her, "To choose is to invent. We can use choices to construct those most meaningful combinations. And that's when we can really experience the power of choice. Choice is not about being reactive to whatever's in front of you, it's about being proactive about creating those choices that enable you to go from who you are today to whom you want to be tomorrow."
Tuesday, May 5, 2020
Carbon footprint of your food
"'Eating local'...[although this] might make sense intuitively – after all, transport does lead to emissions – it is one of the most misguided pieces of advice... emissions from transportation make up a very small amount of the emissions from food and what you eat is far more important than where your food traveled from. "Transport is a small contributor to emissions. For most food products, it accounts for less than 10%" 
A summary of some of the main global impacts:
Food accounts for over a quarter (26%) of global greenhouse gas emissions.
Half of the world’s habitable (ice-free and desert-free) land is used for agriculture.
70% of global freshwater withdrawals are used for agriculture.
78% of global ocean and freshwater eutrophication (the pollution of waterways with nutrient-rich pollutants) is caused by agriculture.
94% of mammal biomass (excluding humans) is livestock. This means livestock outweigh wild mammals by a factor of 15-to-1.
Of the 28,000 species evaluated to be threatened with extinction on the IUCN Red List, agriculture and aquaculture is listed as a threat for 24,000 of them.
Contact time for disinfecting COVID
The fastest disinfection, requiring 30 seconds of contact with wet disinfectant, is with diluted bleach or the highest concentration of benzalkonium chloride (the stuff in many disinfectant wipes.)
https://www.ecri.org/components/HDJournal/Pages/Disinfectant-Concentrations-for-EPA-list-N-COVID-19.
https://www.ecri.org/components/HDJournal/Pages/Disinfectant-Concentrations-for-EPA-list-N-COVID-19.
Monday, May 4, 2020
Do we have coal deposits cuz bacteria couldn't digest trees? - lignin, bacteria, and evolution.
Although the following hypothesis has gained a lot of traction..."Such geobiological hypotheses sometimes persist based largely on the strength of their novelty, without sufficient predictive testing."
"The first trees...could not grow very tall because they didn't have lignin or cellulose, the tough fibers that make the woody trunks of trees. Trees eventually evolved lignin and cellulose and began to grow very tall – up to 160 feet or more."
"Although trees had evolved lignin and cellulose, no bacteria that could digest these woody substances had yet evolved. In fact, those bacteria would take another 60 million years to evolve."
Not so fast. The above "evolutionary lag" hypothesis didn't hold water when examined more closely.
"Boyce and his colleagues took a closer look at this "evolutionary lag" hypothesis, examining the idea from various biochemical and geological perspectives. "Our analysis demonstrates that an evolutionary lag explanation for the creation of ancient coal is inconsistent with geochemistry, sedimentology, paleontology, and biology...showed that shifts in lignin abundance in ancient plant fossils had no obvious impact on coal formation. In fact, many Carboniferous coal layers were dominated by the remains of lycopsids, an ancient group of largely unlignified plants...The scientists instead argue that the waxing and waning of coal deposits during the Carboniferous period was closely tied to a unique combination of tectonics and climate conditions that existed during the assembly of Pangea...you need a productive environment where you're making lots of plant matter and you also need some way to prevent that plant matter from decaying. Where that happens is in wet environments...forces were herding several large land masses together into what would eventually become the massive supercontinent Pangea...as the mountains rose, the basins deepened, and even more plant material could pile up."
Furthermore,
"only ∼70% of the coal organic matter is consistent with the possibility of a lignin origin, the rest being broadly attributed to microbes or algae..."
It would have taken only about a thousand years to accumulate the world's coal reserves, not 60 million years - as follows: "Even if terrestrial productivity were only 25% of the modern levels of ∼55–60 gigatons per year and lignin accounted for 20% of that production [lignin content generally ranges from 5% to 35% in most extant tracheophytes], carbon deposition in the form of lignin would have amounted to ∼3 gigatons per year. The extremity of this number is placed in perspective by considering that modern global coal reserves spanning the entire 420-million-year history of lignified vascular plants are only on the order of a few thousand gigatons. Actual rates of organic accumulation are thought to be at least two orders of magnitude lower, even in the Carboniferous. Despite feedbacks with weathering rates, much smaller imbalances would have resulted in the complete removal of atmospheric CO2 in less than a million years. Without evidence of such dire consequences, lignin production in the absence of lignin decay for more than 100 million years into the early Permian is untenable. Most organic matter decays, regardless of composition, and only accumulates where local stagnant waterlogging results in substrate anoxia"
Saturday, May 2, 2020
Breakthrough Solid State Battery - 900 Wh/L Samsung
At 3:40 - "they achieved a 50% increase in battery energy density"
At 5:39 - "they used a matrix of silver instead of silica to hold the lithium ion, increasing the density of lithium."
At 5:39 - "they used a matrix of silver instead of silica to hold the lithium ion, increasing the density of lithium."
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