What not to wear to a dinner hosted by mosquitos
Posted by mark in Nature, Uncategorized on August 2, 2024
Yesterday I stopped by Minnesota’s Metropolitan Mosquito Control District (MMCD) booth at our local county fair. They display live mosquito larvae swimming in a shallow pan of water. Visitors can pipette them on to a slide and view them with a microscope. Fascinating!
Thanks to the mosquito control services by MMCD (and/or developments reducing habitat) I’ve seen a dramatic decrease in these pests since moving into my home in Stillwater almost 30 years ago. However, there were plenty of ‘skeeters at the Anderson family get-together up north at Pine Terrace Resort last month. While packing for our getaway, my wife advised that to be less attractive to these flying insects I bring white or lightly colored clothes and none with any reds. Being a professional skeptic of such assertions, I immediately looked for any science to support her advice. As usual, she was right, as you can see in this 2022 publication by Nature on The olfactory gating of visual preferences to human skin and visible spectra in mosquitoes.
If you are put off by too much information, watch this LIVENOW interview of co-author Jeffrey A. Riffell—a biology professor at the University of Washington, Seattle. I like his heads-up that mosquitos learn not to bite people swatting them away and go for easier prey. In other words, if you are going for a hike in the woods, bring along someone who would rather get bitten up than look like a city slicker. Then diligently swat all mosquitos over to your trail-mate—better to look like a fool than be bitten-upped cool.
PS: I am a big fan of DEET repellants for deterring mosquitos and, equally important, ticks. I also wear a cap treated with permethrin, which is a real game changer as advised by Hiking Thru Life. Of course, in areas where mosquitos gather in visible clouds, covering up completely, starting with a head net, is the only way to go. Given the huge increase in mosquito-borne and tick-borne diseases in the United States and elsewhere, it’s best to “fight the bite”.
Design of experiments (DOE): Secret weapon for model rocketry
Posted by mark in science, Uncategorized on June 27, 2024
Attracted by its focus on model rockets, I took a summer class on physics at Macalester College in my early teens. What a blast—literally! I really enjoyed learning about force, mass, acceleration and all the other aspects underlying aerospace. (Keep in mind this being the height of the 1960s race to the Moon.) But the best part was building a scale model of the Saturn V featuring multiple solid propellant motors and a parachute recovery system. For the grand finale of our class, we successfully launched our rocket. The parachute did deploy. However, our ship drifted over Saint Paul’s magnificent urban forest (soon to be decimated by Dutch elm disease) and got hopelessly hung up 100 feet overhead.
These great memories from my youth came back to me earlier this year when asked for advice on validating the OpenRocket simulator. The question came in from a mentor using Stat-Ease® 360 software on a low-cost educator license to support a high-school rocket club achieve the American Rocketry Challenge goals for altitude and flight duration. I happily deferred this request for stat help to my colleague Joe—a physics PhD who plays a dual role providing statistical advice and programming. Without getting into the details (after all, this is rocket science!), suffice it to say that, yes, our DOE software does provide “the right stuff.”
By the way, just last week a NASA sounding rocket carrying student experiments reached an altitude of 70 miles. See the video for the launch. (I advanced it to the countdown. After the blast off, move on. That is the only exciting bit.)
What I find most amazing is that the nose cone on this rocket can carry up to 80 plastic cubes as payload. These accommodate experiments by 11-18 year old students. Check out this Cubes in Space STEM program. Page down to the BREAKING NEWS about an important discovery made by a group of elementary students from Ottawa. I recommend you watch the CTV video—very impressive to hear from such science-savvy grade-schoolers. They will go far!
Coin-flip hack: How to call it—heads or tails—to improve your odds
Posted by mark in Basic stats & math on June 12, 2024
As I reported in this 2009 StatsMadeEasy blog, math and stats experts Persi Diaconis, Susan Holmes and Richard Montgomery long ago worked out that “vigorously flipped coins tend to come up the same way they started.”* Based on principles of physics, the “DHM” model predicts about a 0.51 chance that a coin will come up as started. That is not a big difference over 0.50 but worth knowing by its cumulative impact over time providing an appreciable winning edge.
Now in a publication revised on June 2nd the DHM model gains support by evidence from 350,757 flips that fair coins tend to land on the same side they started. All but three of the 50 (!) co-authors—researchers at the University of Amsterdam—flipped coins in 46 different currencies and finally settled on 0.508 as the “same-side bias,” thus providing compelling statistical confirmation for the DHM physics model of coin tossing.
This finding creates many potential repercussions, for example on NFL football games going into overtime, particularly under the old rules when a team that won the coin toss could immediately win with a touchdown. The current rules provide one chance for the opposing team to tie under these circumstances. Nevertheless, it seems to me that referees should randomly pull their coin out without knowing which side came up, keep it covered up from sight of the caller and then flip it.
Let’s keep things totally fair at 50/50. (But do sneak a peek at the coin if you can!)
*Dynamical Bias in the Coin Toss, SIAM (Society for Industrial and Applied Mathematics) Review, Vol. 49, No. 2, pp. 211–235, 2007.
Common confusion about probability can be a life or death matter
Posted by mark in Basic stats & math on June 3, 2024
As a certified quality engineer (CQE), I often focused on the defect rates of manufactured products. They either passed or failed—a binary outcome.
I learned quickly that even a small probability of failure would build up quickly when applying a series of operations. For example, I worked as chief CQE on a chemical plant startup that involved several unit operations in the process line—all to a scale never attempted before. It did not go well. By my reckoning afterwards, each of the steps probably had about a 80/20 chance of succeeding. That led to optimism by the engineers in the company who design our plant. Unfortunately, though, multiplying 0.8 repeatedly is not a winning strategy for process improvement (or gambling!).
As we approach the 80th anniversary of D-Day this diabolic nature of binary outcomes takes on a deadly aspect when you consider how many times our warriors were sent into harms way. The odds continually waver as technology ratchets forward on the offense versus defense. This can be assessed statistically with specialized software such a that provided by Stat-Ease with its logistic regression tools. For example, see this harrowing tutorial on surface-to-air missile (SAM) antiaircraft firing.
Thanks to a heads up from statistician Nathan Yau in one of his daily Flowing Data newsletters, I became aware that many people, even highly educated scientists, get confused about a series of unfortunate or fortunate events (to borrow a phrase from Lemony Snicket).
Yau reports that a noted podcaster with a PhD in neuroscience suggested that chances could be summed, thus if your chance of getting pregnant was 20%, you should see a doctor if not successful after 5 tries. It seems that this should be 100% correct (5 x 20), but not so. By my more productive math (lame pun—taking the product, not summation), the probability of pregnancy comes to 67%. The trick is to multiply the chance of not getting pregnant—0.8—5 times over, subtracting this from 1 and then times 100.
If you remain unconvinced, check out the odds via Yau’s entertaining and enlightening simulation for probability of success for repeated attempts at a binomial process.
Enjoy!
A solution for saving migrating birds from disorienting light pollution
Posted by mark in Education, Nature, science, Uncategorized on May 3, 2024
My grandson Archer and his class of sixth graders at Stillwater Middle School advanced to last week’s national Solve for Tomorrow competition in Washington, DC–an amazing accomplishment at their age. The event, sponsored by Samsung, empowers students in grades 6–12 to leverage the power of STEM (science, technology, engineering and math) to create innovative solutions addressing critical issues in their local communities.
Archer and his classmates focused their attention on reducing the impact of light on bird migration patterns in the St. Croix Valley. They developed a very inventive plan that featured bioluminescence; sensors to reduce unnecessary light and a flower-petaled, controllable cover for directing streetlights downward.
Being one of just 10 schools across the country to be named national finalists, they earn $50,000 in Samsung technology and supplies for their classroom. To top it off, Archer and his classmates won an additional $10,000 by winning the Community Choice award based on a popular vote.
I expect Archer and all will go far by their STEM power. Hopefully, the birds will also continue to go far by being better protected from light pollution along their way.
A “divine and cosmic” geometric shape—practical and pleasing
Posted by mark in architecture, geometry on April 15, 2024
The Venice Beach Pavilion—just a short walk away from my winter home in Florida—features a distinctive hyperbolic paraboloid roof dating back 50 years. I love its elegant wavy shape that sails into the sky. Therefore, I am rooting that the City succeeds in getting this iconic structure—characteristic of the Sarasota School of Architecture—registered as an historic landmark, thus enabling funding for badly needed repairs.
Check out an overhead view of the Pavilion here. It is far more impressive when seen from below. There’s no better place to enjoy a fried shrimp basket at a shady mid-century modern, round-concrete table being cooled by the ocean breeze and soothed by the sounds of crashing waves.
The best way to describe the hyperbolic paraboloid is it being the shape of a Pringles potato chip. It’s easy to create in Stat-Ease software by setting up a full three-level response surface design on two factors and then entering a quadratic equation via its simulation tools. The 3D view below stems from a model that includes only a two-factor interaction term, which creates the simple, but pleasing, twisty surface similar to the Venice Pavilion. However, the colors may be a bit much. ; )
“The hyperbolic paraboloid has been seen as a representation of the divine and the cosmic. Its symmetry (one axis but no center of symmetry) and balance have been seen as a reflection of the inherent order and beauty of the universe.”
Nick Stafford, Pringles, A Reflection of the Order and Beauty of the Universe
Weather Tiger predicts a “hyperactive” hurricane season
Posted by mark in Uncategorized on April 3, 2024
Owning a second home In Venice, Florida just a few blocks from the Gulf is great for me and my wife Karen to dodge winter (she really, really hates the cold!). However, there’s always a catch to the good things in life: From June 1 through Nov. 30 our snow haven stands in harm’s way of hurricanes.
Hurricane Ian created quite a scare in September of 2022 before veering south just before landfall. Whew! Last year our closest call came from Idalia in late August—it hitting hard at Category 3 in the Big Bend region of Florida.
This year could be a doozy according to the Weather Tiger, who provides “expert analysis of Florida hurricane threats, with a twist of dad humor” (my kind of guy!). He predicts a “75% chance of hyperactive hurricane season with likely US landfalls.”
“Our model boldly suggests a 10% to 15% chance that 2024 bests 1933’s record for the most intense season, though laying firm probabilities on outliers is a statistical mug’s game.”
– WeatherTiger President and Chief Meteorologist Ryan Truchelut, 3/28 Sarasota Herald
Accuweather’s forecast for the 2024 hurricane season is even more hyperbolic—describing it as “explosive” and “super-charged” and warning that “forecasters may even run out of names for storms amid a frenzy of tropical systems.” Oh, my!
Good thing I just did an extensive remodel to bolster our 1960 cinder block home with a new roof, high impact windows, flood vents, etc. Bring it on!
On second thought…do not.
Scroll sawers put blades to the statistical test by cutting out ducks
Posted by mark in Uncategorized on March 3, 2024
Years ago I helped Quality Assurance Manager John Engler solve a tricky issue at Robinson Rubber via design of experiments (DOE). He contacted me last fall to help him apply DOE to a nagging question about scroll sawing: Does it pay to buy pricier blades?
We worked together to design a simple-comparative randomized-block experiment on 10 competitive blades. John enlisted 20 fellow hobbyists in his NorthStar Scrollers club to cut out a duck from pine (see pattern below) using the selected blades (such as the one taped on the board) in a random order.
They then rated the results on a 1 to 9 scale—higher the better—for speed of cut, blade jumpiness, fuzzies (undesirable!), edge smoothness, burns and line following.
The blades differed significantly by all attributes at p < 0.0001 other than the line following (p = 0.3419). For the most critical measure—speed of cut, blades 3, 8 and 9 stood above all others on average.
The power of doing 21 replicates—widely spread as indicated by the red dots—and, furthermore, blocking out the scroller-to-scroller differences, is seen by the narrowness of the least significant differences (based on a p of 0.05).
Accounting for all the attributes via Stat-Ease software’s multiple response optimization these three blades held up overall with number 3 being the winner by costing less than the other two.
After I reported my findings to the group, John laid out a number of mitigating factors:
- Experience of the scroll sawers
- Type of wood, e.g., something a lot harder
- The life of the blades (important to consider for the cost)
But all-in-all, this planned experiment proved to be a big hit with the NorthStar Scroller hobbyists. What impressed me was their depth of knowledge on scroll-saw blades and why we observed such significant differences due to the patterns and orientation of their teeth, etc. I was also struck by how some individuals could tell right away which blades worked best—even before seeing the entire set of data. This reinforces my feeling that laying out and analyzing experiments works best by combining the know-how of a DOE expert (like me) with subject matter experts (not me in this case—far from it!).
“This went much better for me than I thought it might and I learned some things about blades along the way. This was fun!”
–Helen (a NorthStar Scroller blade-tester)
Classic case of sensory testing snubbing off a beer snob
Posted by mark in food science on February 26, 2024
The feature story on sensory evaluation in the new issue of ASTM Standardization News brings back a fond memory of a rare victory over an overly smug colleague.
I developed a taste for sensory science as a young chemical engineer determined to prove that mass produced American lagers differed only imperceptibly—consumers being brain washed by deceptive advertisers. This hypothesis drew strong condemnation from one of my colleagues—a chemist named Harold who dissed lesser brews such as Old Milwaukee, which he deemed “Old Swillwaukee”.
To put this beer snob to the test, I organized a tasting at a Super Bowl party attended by a dozen or so fellow researchers. Beforehand, I engaged a sensory professional that our employer hired to guard against “off odors” from our manufacturing plants. She advised that we limit drinking of each beer to a small sip, then eat saltless crackers and wash them down with water before going to next brew. Also, both the presenter of the beer and the taster should be blind to the brand, thus avoiding bias.
However, given my mission to snub a beer snob, we first rated a selection of undisguised beers—including Miller, Budweiser, Old Milwaukee and others (in those days there were no ‘craft’ brews*). Harold rated “Old Swillwaukee” dead last. That was my plan! Then we repeated the tasting with the order re-randomized, but this time not revealing the names. Harold rated Old Milwaukee at the top of his list, thus providing a Super Bowl victory for me (badly needed being a Vikings fan).
My conclusion from this experience, and my work over the years helping food scientists improve the taste and other attributes of their products, is that it would be best to adhere by ASTM’s upcoming revision to Guidelines for the Selection and Training of Sensory Panel Members. For beer and the like, then bear down on the Standard Guide for Sensory Evaluation of Beverages Containing Alcohol (E1879).
We make panelists learn chemical names. For example, isoamyl acetate is a specific compound that smells like candy banana…I make panelists drink heavy cream for mouthfeel attributes. They’re unfazed by whatever we give them anymore because it’s always weird.
– Ali Schultz, sensory manager, New Belgium Brewing Company and leader of the current revision to E1879 (“Accounting for Taste”, ASTM Standardization News, January/February 2024)
However, if you are having a party, it’s more fun to be unprofessional and ignore the mandates to sip and spit, etc. ; )
*PS: The specialty beer brewers are getting a bit out of control nowadays, IMO. For example, I just got an alert from my Stillwater, Minnesota neighborhood microbrewer Lift Bridge to their release this weekend of Taking Care of Breakfast—a “barrel aged imperial breakfast stout aged in 10-year Willet and 6-year Wild Turkey bourbon barrels, infused with peanut butter and banana chips.” This new brew comes in at 12% ABV. Perhaps it may be best to go with orange juice first thing in the morning.
To bean or not to bean, that is the question for coffee
Posted by mark in food science on February 13, 2024
In my most recent blog post on coffee I reported that a finer grind may not always be better. Now another piece of the puzzle for producing java that jives falls into place: Spritz your beans with water.
Evidently this is not a new discovery—those who really know their coffee-making craft routinely moisturize their grind to reduce clumping. A new study reported here by New Scientist reveals the problem: static electricity. Following up on the link to the original publication, I see that the research team, led by a volcanologist (sensible considering the lightning generated by particle-laden eruptions), deployed this $3000 German-made, handcrafted machine to produce extremely uniform grinds. I will definitely buy one soon (after winning the lottery).
Another approach to better coffee takes a completely different route—create it from cells grown in bioreactors. Environmentalists like this because the demand for sun-grown beans leads to destruction of rain forests. Per this Phys.Org heads-up, a Finnish team just released a recipe to accelerate the creation of a new “coffee ecosystem.” This seems promising. But there is a problem: Though the current lab-grown concoctions contain twice as much caffeine as ever before, it remains much lower than those in farmed beans.
Another approach to avoid the problems keeping up traditional methods for making coffee is to go to a beanless brew, such as the imitation now being rolled out by Seattle-based Atomo Coffee. Based on this January 24th report by CBS Saturday Morning show, I would be willing to give it a try, especially given they load up their brew with caffeine at the upper end of the normal range of real coffee. Full steam ahead!
One last idea (my caffeine levels now running low) for improving the taste of coffee is being selective about the shape and material of your cup. For example, see what the Perfect Daily Grind says about pouring your brew into a wine glass or other specialty containers.
“A drinking vessel has a significant impact on perception of flavour and aroma because it changes the way the coffee smells and tastes, as well as how you drink coffee. What’s more, our senses, feelings, and emotions also impact how we experience coffee.”
Marek Krupa, co-founder and CFO of Kruve