omenti

natural conditions

a minipost

Natural conditions impact outdoor sports.  Tokyo in late July and early August is "interesting" - it's very hot with humidity rated as oppressive about 60% of the time.  Pleasant weather doesn't return until the Fall, but TV demands drive the Olympic schedule.  Some endurance events will probably be run at night and athletes will be adding high temperature conditioning to their training routines in the next month or two.   Excessive heat has important physics and physiology consequences and the understanding of physiology has changed a lot in the past decade (you can drink too much in endurance events and electrolyte drinks are ineffective).  Perhaps something for future posts, but for now let's stick with the wind.  

 

During the Olympics Tokyo will probably have consistent winds around 7 mph mostly from the South or East.  To establish a record events like the 100 and 200 meter sprint, 110 meter hurdles and the long and triple jumps record the wind velocity and require a trailing windspeed to be less than 2 meters per second - about 4.5 mph - measured at the track.  The wind doesn't matter much within a race, but qualifications can be biased if the wind changes much between qualifying events. 

 

You'd think a tailwind would always be advantageous for hurdlers, but they have to mentally adjust their strides and launch points for a variety of winds and only the best can handle a variety of conditions.  Long jumpers have to adjust their approach to launch as close to the takeoff point as possible and not foul. Assuming they succeed, a trailing wind can be a big advantage.  Except for record setting pole vaulting is similar.  The height they clear is related to the square of takeoff speed so a tailwind can be a big help.  Oddly there's no wind assistance limit for records. Perhaps an approaching hurricane would be useful in world record attempts.

 

Closed road course races are problematic.  One might think tailwind and headwind portions average out, but if the wind is at a constant velocity, the headwind portions are always slower (here's a simple explanation).  Of course there's the larger problem of shoe performance so maybe we're at a point where records aren't terribly meaningful in running.

 

For some sports the wind adds an interesting dimension.  The density of a beach volleyball is low compared to other most other sports balls, so the wind makes a big difference.  Additionally volleyballs have interesting aerodynamic properties in airspeeds between 14 and 17 meters per second - speeds commonly seen in the women's game and exploited by the better players.  Teams must to adjust for windspeed and direction, but events often go on in strong  and gusty winds - sometimes with heavy rain, which is not unlikely in Tokyo during the Olympics.  

 

Many other sports are impacted by the wind, but last Spring the final project in a science of sports class I taught got my attention.  An amateur bicycle racer/biology major proposed human powered flight.   You would charge a battery by frantically pedaling  generator.  After some amount of time you'd take flight adding whatever power you could muster with your legs to what the motor could produce. Finding the right limits for weight,  charging times, and allowable technologies would make or break the sport.  It probably wouldn't be tmuch of a spectator sport, but it would make a great project for engineering students. 

 

looking at the algorithmic economy

minipost

If you think about how society and the Internet, you probably know about Joan Donovan of Harvard's Shorenstein Center.  Among other things she's known for rejecting the notion of the "attention economy" as being somewhat gas lighting.  Instead she uses the phrase "algorithmic economy."

Andy Revkin of Columbia interviewed her this past Friday as part of his Sustain What series.  She talks about the possibility of a path to a public interest Internet while safeguarding speech.  Also how disinformation memes develop and need to be watched and how the current control of interests on the Internet fail.   You may or may not agree with her, but she's one of the deeper thinkers in this area and this is a particularly clear introduction to what she's about.  Andy does a great interview job, pushing back here and there to go deeper.  An excellent way to spend an hour.

leaps of faith

minipost

Yesterday I had my first jab of a Covid-19 vaccine - specifically the Pfizer mRNA vaccine.  Despite political, production, and distribution issues several vaccines appeared and more are coming.  Going from decoding the SARS-CoV-2 genome to first injections took only about a half year and a year later a few hundred million doses have been produced. While some corners were safely cut, the real story - at least for the new mRNA vaccines - began nearly thirty years earlier.  

 

Katalin Karikó's work will certainly win her a Nobel Prize next year.   Here's a good telling of the story.  A major point is the work was judged unworthy and finding support was nearly impossible.  After about ten years another player, Drew Weissman, entered and the two of them managed to crack the final bits of the problem.  He'll certainly be sprinkled with the Swedish holy water too. The mRNA approach is important well beyond the current pandemic - it may mark a fundamental change in medicine.  It wouldn't have happened - at least not as soon as it did - without a certain type of reserch.  

 

Curiosity-driven fundamental research requires a certain type of scientist, time and resources.  While much of it fails to produce an immediately useful result,  it has an established track record of changing the world.  Industries don't do this kind of work anymore.  Most universities shy from it - there's a tendency to want results-focused work.  When it's funded you usually find it in physics and astronomy  rather than the biological sciences and that's a problem.   These leaps are driven by hope and curiosity.  They open doors that often require more than a decade of work - usually by other people in different organizations.   Expanding this work is how you create radical change.  I'd never argue results-driven research should be cut - after all, that's where the next five to twenty years come from.  But I'd love to see the Katalin Karikós of the world given more of a space.  And then there are the spin-offs - a good deal of the instrumentation used in medicine came out of  fundamental physics - but that's another set of stories.

 

making the whole more than the sum of the parts

Basketball is my first love, but the athleticism of beach volleyball is amazing.

_____

Watching the men and women spike, block, and dive around a court that is almost impossible for two people to adequately cover makes one appreciate the elite level of athleticism necessary to be competitive on an international level. After basketball, it may very well may be the second-most exciting international sport.  

Kareem Abdul-Jabbar 

 

Sport is often seen as a microcosm of society.  It brings disparate groups come together to peacefully play, watch and cheer.  Sometime it's a vehicle for highlighting social issues and even bringing change.  Looking around more carefully you find more - teamwork is a good example and I'll go there.  

 

People tend to have favorite events.  My wife likes gymnastics, ice skating, and weight lifting (she lifted as an amateur).  I like a few Winter sports, but my favorite sport is beach volleyball.  Requiring little in the way of equipment and having simple rules it's a fairly clean sport.  Easy for some people to get together and knock a ball around as well as being very difficult to master.  Played at the highest levels it's a mental game of strategy and tactics.  Successful two person teams require a set  skills a single player rarely has forcing a mixture of  specialization along with a generalist's skill.  It's this  difficult simplicity that attracts me.¹  

 

The real reason for the post is to focus on what makes a successful team.  The best teams tend to have a mixture of physical characteristics, types of athleticism and approaches to the game play.  Communication and reading the game and the other players are critically important.  High level players develop court sense - they know where the other players and ball are as well as how that information is changing with time.    And it's just them - they can't use a coach during the game.

 

Sarah Pavan is a friend and half of the current women's world champion team that was just named one of the most significant volleyball teams of the last decade.  (the link is worth checking out as it shows some of what makes them an unusual and great team)   They're an example of finding success by celebrating differences.   Sarah is shy and somewhat introverted while Melissa Humana-Paredes, known in the sport as the smiling assassin,  is a five alarm joyful extravert.  Sarah is a strategic player, some call her the most cerebral player in the game, while Melissa is one of the most intuitive players.  They manage to bring their differences together without changing each other.  

 

Social scientists who study teamwork in the workplace, military and other areas regularly point out three main components of the most successful teams (individual skill is not one of them): the ability to communicate freely, empathy (that's a loaded word, but I'll leave it at that), and having women on the team.   I sent a video link to a match to a professor who studies verbal and non-verbal communication.  She noted Sarah and Melissa appear to have mastered an almost off-the-chart skill level.  Empathy is more difficult to nail down, but these two seem to know what each other is thinking on and off the court.  And, of course, they have women on the team nailed down.

 

There are probably lessons here and in other areas of sports applicable to teams outside of sports.  I've had a couple of fascinating discussions comparing and contrasting the dynamics of physics collaborations, movie animation teams and beach volleyball. 

__________

¹ Not quite the whole story.  There isn't a lot of money in the sport and the players are very approachable and enthusiastic. It's part of the sport's atmosphere.   I'm also interested in the physics of what's going on, but that would probably happen in any sport - the first time I seriously watched curling I had to work out why the stone curled the "wrong" way. 

 

measurement grounded activity recommendations

A minipost on staying healthy

 

For the last twenty years or so it's been increasingly clear that exercise is a powerful drug large benefits and few if any downsides.  Recommendations for how much across wide ranges of populations are improving, but historically have been educated guesses and extrapolations based on inadequately sized studies.  Fitbits, Apple watches and other wearables that measure and record movement are revolutionizing how the science is done.  Study sizes and data quality have increased dramatically and are being correlated with real measures of health from physicals and other widespread measures.  New targeted recommendations based on the improved studies are emerging with recommendations for various age groups and differing physical abilities and medical conditions, acceptable sedentary behavior, a better understanding of the depression-fighting power of physical movement and so on.  

 

The British Journal of Sports Medicine has dedicated their latest issue to the new device-grounded WHO physical activity recommendations and has posted it outside their paywall. Perhaps most important is the WHO 2020 Guidelines article, but most of the articles are interesting and written for the non-specialist.  They also posted an informative twenty minute podcast episode:

BMJ talk medicine · The 2020 WHO Guidelines on Physical Activity with Prof Fiona Bull and Dr Juana Willumsen. Ep #456

 

If you're looking for some serious strength and conditioning exercises, Sarah has put together a few on her YouTube page. They're aimed more at those already in good shape who don't have access to a gym.  Just look for those labeled strengthening and conditioning - the rest are aimed at beginning volleyball players.  At the other end of the scale walking is an excellent exercise.

And a simple recommendation from me.  Getting out in the cold weather away from people is an excellent way to get exercise.  As a native Montanan I offer one bit of advice on dressing for the cold: layered clothing.  It can make the difference between a pleasant bit of outdoor activity and being cold, wet and miserable. 

 

 

 

checking out your neighborhood

minipost and recommendation

The books you wore out when you were fourteen or fifteen are probably serious hints about your dreams and direction.  One of the two I wore out was a Norton's Star Atlas and Reference Handbook.   Beautiful, wonderful star charts to find your way around the night sky.  The graphical design was (and still is) stunning and it just works.  It cost a fortune in the day, but so wonderful.

 

Every now and again someone publishes a survey that claims only a small fraction of Americans under 30 or 35 have seen the Milky Way. That's a shame.  On a sufficiently clear dark night it's about as beautiful as anything I've seen in Nature.  Light pollution has largely taken it from us.

 

But even in suburban areas you can still see some stars and planets and the Fall in much of Europe and North America offers crisp clear skies.  Checking out our stellar neighborhood is much more inspiring than watching TV, but you need a guide to make any progress. Although I still love my Norton's (I've been through several editions), the better entryway is to use an app.  At least a dozen exist.  My clear favorite on iOS is Sky Safari at about three dollars on the App Store.  (they also have an Android version, but I haven't used it).  Go for the low-end version - currently Sky Safari 6 AR - the more expensive versions are used to drive computerized telescopes.

 

The beauty of apps like this is they know location and the time of day.  Then, using the phone or pad's compass and gyroscope, they calculate and display the section of sky you're pointed at.   Change the display magnification to roughly match the sky and it's sort of augmented reality. You can identify stars and planets as well as search for them and learn the constellations. Playing around with the settings is useful (particularly turning off the background music), but the defaults for star brightnesses displayed roughly matches the human eye in a semi-dark area.  You can also turn off the compass and gyros and explore the sky indoors.

 

If you get hooked the next thing would be a good pair of binoculars .. stay away from telescopes for awhile. 

 

 

 

take it outside

a minipost

 

Other than the new graduate student, most of us have worked together for a few years.  This morning we carried our folding chairs across the large lawn struck by the novelty of seeing each other without glass, silicon and coordinated electrical signals getting in the way. It was our first face to face meeting since late February.

 

It would have happened earlier if we didn't believe the SARS-CoV-2 coronavirus couldn't be effectively carried by aerosols, but there's too much evidence to the contrary.  Aerosol clouds move and disperse quickly outdoors, so here we were with our face masks and some distance from each other.  Someone brought an easel with large sheets of paper and a few markers and we were off.  

 

A few things cropped up right away.   It gets hot sitting in the Sun for any length of time (you'd think we'd have more sense, but my type generally lacks it).  It was difficult hearing each other.  I can imagine a smartphone app that could take care of that - a local audio conference cloud.  (Gregg - this would be a good student project - I can think of several ways to do it).  One could also imagine iPad screen sharing, but I don't think it would work as well for our discussions - your mileage may vary.

 

We did manage to get a lot done - much more than the Zoom calls we've had.  There's a lot of "out of band" communication that takes place when you're face to face. 

 

I doubt that many would do this on a regular basis, but it raises an interesting point.  Indoors plus an aerosol transmission vector are a bad combination.  To make indoors work you need good fresh air exchange - perhaps a room volume every few minutes.  (Exactly how thoroughly and quickly isn't well-known yet.  This isn't anywhere as bad as measles for example.) Opening windows and doors using fans can do it.  The same with a properly balanced HVAC system .. but that can be difficult and expensive.  Most building systems recirculate air.  You can pass the air through a high-spec HEPA filter (note - HEPA is not a type of filter, but rather a standard).  Unfortunately they restrict airflow and it takes a lot of power to push air enough through.  I'd bet a fair amount of money most classrooms and offices aren't up to the task.

 

I jokingly suggested perfume, cigarette smoke, or incense smoke as a test to someone who studies aerosol physics.  They said it was a good idea.  You shouldn't be able to smell these kind of sources in a properly ventilated room unless you're very close.  Another test is CO₂ level.  A classroom full of people shouldn't register over 800ppm after an hour has gone by.  Building managers are often equipped to test CO₂ and volatile gas levels (you shouldn't be able to smell the carpet either). 

 

In many countries this won't be a big deal.  They've managed to get a handle on the situation with the ability to find and isolate hotspots.  How safe it is to have k-12 kids in schoolrooms is likely to be an experiment we'll see played out.  Colleges, restaurants and bars are probably a clearer call. Such decisions are well beyond my pay grade. 

 

 

there were always roads

I had the pleasure of chatting with and, more importantly, listening to Rhinnon Giddens.  She's become well known for tracing the importance of African Americans in music and, at the same time pointing out origins are complex and probably too complex to disentangle.

 

She's a singer, composer, and a fine claw hammer banjo player.¹  These days the banjo is most associated with the white South.  It turns out it came from the Caribbean with slavery and was almost exclusively a black instrument until the 1830s and 40s when white America started to absorb it. From there you can follow it back to Africa and from there to the middle East.  

 

Here she plays an Appalachian piece with Francesco Turrisi accompanying on  a middle Eastern frame drum.

Oddly enough the Irish bodhrán is a very recent instrument based on frame drums from the Middle East - so it fits.  

 

Many - probably most - of our musical styles have has roots elsewhere.  These ancestors also have roots and interconnections.  Trade created a cultural connection machine that made its presence known to people who had no idea where the influences were coming from.  It doesn't take too many people to show up on another shore something new - what can seem like straight-up magic.   Then culture takes and modifies what it finds as it grows.

 

There is no unique source or single direction.  

 

There were always roads...

__________

¹ She's also a MacArthur fellow.  Her music is powerful.  You need to listen.

 

playing with popcorn

A minipost

 

Chatting with Sarah the topic of snack foods somehow came up.  She mentioned problems getting all of the popcorn kernels to pop and sometimes there was burning. We wandered to something else, but afterwards it struck me that proper popcorn popping was something I know how to do.  In fact a few scientific papers have been written and it's a good area for home experimentation. But first the recipe:

 

Our next door neighbor when I was in high school, had it down.

° 1/3 cup of fresh popcorn .. he'd keep it in a sealed glass jar.  

°  3 tablespoons of vegetable oil in a 3 quart heavy bottomed sauce pan over medium high head. Add 3 or 4 kernels of popcorn and wait.

° When they pop add the rest of the popcorn and lift the pot away from the heat for about 30 seconds.  Put on the cover and return to heat.   If you can it's a good idea to leave the lid slightly ajar to release some of the steam (his lid had a vent)  When the popping slows to once every second or two, dump the popped corn into a bowl and add salt and melted butter to taste.

I use an inexpensive light olive oil (not a rich or expensive one) and add a bit of salt when the popcorn goes into the oil.  I prefer white popcorn, but your taste may vary. Jolly Time comes in thick plastic bags that are fairly air-tight.  Upscale popcorns come in glass jars, but I'm cheap.  

 

Popcorn is a special variety of corn.  The kernel has a hard thin hull on the outside. Inside is the seed along with enough water and a starchy food to get it sprouting.   The trick is to get the water inside to boil.  The hull is strong enough that it takes quite a bit of pressure to get it to burst. As the starch heats it gelatinizes.  The hull bursts at a weak spot and the gelatinous starch cools and solidifies as it expands outwards. The expansion is asymmetrical starting at the weak spot where the hull burst giving the mass a kick. The sound comes from the expanding gas resonating against the expanding kernel and not the breaking hull. No one figured the sound part out until a couple of years ago.

 

If you have kids or some curiosity on your own you can figure out a few things:

 

Find an oven-safe bowl with a lid and heat your oven to about 190°C (375°F).  Add a small number of kernels - say 20.  You may have to shake the bowl around a bit as it heats.  After the popping stops count successful pops.  Now try it at about 170° C (about 340°F).. your count should be different.  If you like you can find the threshold.  You might need to calibrate your oven.  I use an infrared thermometer.   (180°C seems to be the threshold for fresh Jiffy Pop white).

 

If you have a good scale weigh 20 or 30 kernels and calculate the average weight of a kernel.  Put them in the hotter oven and pop as many as you can.  Weigh the popped kernels and calculate the moisture percentage.  I get close to the 14% moisture content good popcorn is supposed to have.

 

You can try different types and freshnesses of popcorn and find popping yields (percent popped). You can also measure the average size.  Try it at a different altitude if you can or enlist a friend.  Try slicing the kernels and see what that does to the size.  How different are the fancy varieties?  And of course you can try toppings other than butter.

 

While on the subject of snack food. Sarah told me about maple cotton candy.  It isn't easy to find in the US, but I finally did.  Expensive, but very good and addictive.  Be warned.

 

 

 

order! - a minipost

Apparently a math puzzler became something of a theme on the Internet..  a half dozen people asked me what I thought the answer was

8÷2(2+2)=?

Some came up with 1, others with 16.  Apparently there were near-religious arguments. A mathematician would tell you both are incorrect - the question posed is ambiguous and not an answerable bit of math ..  at least not generally.

 

The problem is the order in which one evaluates expressions.  It turns out the one you learned in grade school is a bit different from the one you may have had when you learned algebra. If you remembered grade school you probably get 16.. algebra people are more likely to get 1.¹  If your algebra teacher was more careful they would have said the expression is wrong - you need to add parenthesis to make it unambiguous. The exception would be if the only people you communicate with agree on representation. That can be a big if..

 

Taking it a bit further, the simple rules you learn in secondary education don't cover don't cover unary ±, which implicitly have lower precedence than exponents on one side and higher on the other!  For example

-x³ → -(x³)
x^-3 → x(^-3)

This is so well agreed upon that no one uses parenthesis in this case.  Historically juxtaposition was treated as implicit multiplication, but that led to ugliness like

1/3x →  1/3*x →  (1/3)*x
a^2x →  a^2*x →  (a²)*x

uck! 

People decided juxtaposition of numeric literals is like a unary operator ..  so the 2 in 2x is attached to the x like the - in  -x.  

 

Back to the original problem. The fact that people had different interpretations and mentioned rules from school meant a better rule was required.  The problem needs to be unambiguous to anyone who might encounter it.  This is an issue for computer languages - different languages can parse the same written expression differently and come to different results.  Agreement on standards is an issue too ..  the Mars Climate Orbiter was lost as  teams at JPL and Lockheed Martin had different takes on a single critical bit of data - one used metric units, the other english..   when the retrorockets on the spacecraft were fired to go into Martian orbit the spacecraft burned up in the Martian atmosphere - it was literally lost in translation.  And this was code that passed multiple very careful reviews - code written for space probes is some of the carefully crafted software period.  Just wait for complex coordination systems and things that move with people nearby or inside.

 

That said there are some areas were common agreement among practitioners creates a local set of standards..  Einstein summation notation in physics is confusing to outsiders, but all physicists know it. And then there's my favorite - the double factorial.  In math (n!)! is not n!! ...  (note that I also have the problem of people interpreting ! as an exclamation point:-)

 

This local agreement is probably true in most fields - even descriptions of an action in a sport are local to the sport.  We all use local shorthand - it's a form of jargon, but we need to know when we can use it and when we need to be more general even it it's awkward.

__________

¹ In one case 8÷2(2+2) → (8÷2)*(2+2) = 4*4 =16

   in the other 8÷2(2+2) → 8÷(2*(2+2)) = 8÷(8) = 1