Archive for category Uncategorized
Banging my head against the wall about concussions in football
Posted by mark in sports, Uncategorized on October 17, 2021
Being a big fan of football at all levels—grade school (oldest grandson Archer, pictured, going good on the gridiron), high school, college (season-ticket holder for Golden Gophers) and NFL (long-suffering Vikings fan), I hate to see players going down with concussions and their long-term effects of chronic traumatic encephalopathy (CTE). I suffered several sports-related concussions myself, which makes me even more keen to see advancements in their prevention. Therefore, I was excited to see this report by ESPN on soft-shelled helmets being tested by NFL players.
Unfortunately, however, the statistics on impact reduction, less than 10%, do not appear to warrant putting on a comically squishy covering over a hard-shell football helmet. The advantage is just too marginal. On the other hand, when doing anything involving an appreciable risk without a helmet, for example, riding a bicycle, wearing one becomes essential for concussion reduction. According to this 2017 article in the Journal of Neurosurgery on helmet efficacy they provide significant protection against “devastating intracranial injury”—skull fractures and the like.
Therefore, I am pleased that, unlike most of his teammates, Archer wears his unglamorous helmet.
However, the bad news from neuroscientists is that helmets are “not efficacious” for protection against concussions.
Heads up!
Fly often, fail often, test often
Posted by mark in science, Uncategorized on September 27, 2021
Being addicted to experimenting, I greatly admire the “fly often, fail often, test often” spirit of the University of Minnesota Rocket Team. On Thursday these student rocketeers updated us engineering and other U Mn alums on their latest exploits, including a win and Overall Award in the 30k bracket of the Spaceport America Cup 2021.
Having grown up during the Space Race and celebrated my golden 16th birthday the day Apollo 11 launched off to put the first man on the Moon, I am keen to see such great leaps in technology for amateur rocketry. It astounds me that a group comprised mainly of undergrad aeronautical engineers can design and build an aircraft reaching 30,000 feet (and much higher if not prohibited by the FAA). That beats my personal-best for rocketry by 29,970 feet or so, ha ha.
“It all looked so easy when you did it on paper — where valves never froze, gyros never drifted, and rocket motors did not blow up in your face.”
Milton W. Rosen, rocket engineer and project manager in the US space program between the end of World War II and the early days of the Apollo Program.
With such great “can do” spirit, willingness to fail, and the high-tech resources of our College of Science and Engineering, the flying Gophers will go far in future, I feel sure.
Tomatoes may turn you into a zombie
Posted by mark in Nature, Uncategorized on August 24, 2021
The latest issue of Chemical & Engineering News reports alerted me to the discovery by a team of Brazilian botanists that tomatoes communicate sensory information back to their parent plant. The scientists worked this out by letting a hungry caterpillar gorge on wired-up Micro Toms much like my ripening cherry tomatoes (pictured). This seems a bit callous to me from the perspective of a plant. However, it is sweet for the sake of science (and the future butterfly).
Based on statistical analysis of the variation in signals*, the researchers concluded that the tomato plant sensed its fruit being eaten. Therefore, they hypothesized that the parent could fight back by emitting chemicals such as this one discovered by a University of Wisconsin biologist that makes attacking caterpillars eat each other .
Be careful the next time you squeeze tomatoes on the vine to check their ripeness—they might not like it and take revenge by turning you into a zombie. (Wow, that took a dark turn!)
* For experimental details, see Fruit Herbivory Alters Plant Electrome: Evidence for Fruit-Shoot Long-Distance Electrical Signaling in Tomato Plants, Frontiers of Sustainable Food Systems, 20 July 2021.
Squids out of water seeking escape from vicious double-jawed eels
Posted by mark in Nature, Uncategorized on June 23, 2021
Two science reports on squids caught my eye today. On the one hand, the New York Times informed me that “When an Eel Climbs a Ramp to Eat Squid From a Clamp, That’s a Moray”. It’s not so funny for the squid who get sucked down off of dry land by creatures with two jaws—an outer one to seize their prey and an inner one that leaps forward to drag it deeper. That’s really creepy. If you have a strong stomach, check out this video by Rita S. Mehta, an evolutionary biologist at the University of California, Santa Cruz. She and her colleague report all the gory experimental details in this month’s Journal of Experimental Biology.
The second bit of news about squids—this one from Complex—seems a bit cheerier: NASA Launches Dozens of Baby Squid Into Space for Experiment. Learn more about this mission by University of Florida researcher Jamie Foster here. Check out the video of the cute little baby squids. Far out!
PS: Heads up: Squids can fly, as detailed in this January 2021 TED-Ed video:
Illuminating results from sparkler experiment
Posted by mark in Education, pop, Uncategorized on April 16, 2021
This video, concluding with the obligatory lighting up of multiple sparklers, lays out the results of another fun and educational experiment by Chemical and Biological Engineering (CBE) students at South Dakota School of Mines and Technology (SDSMT) for their Applied Design of Experiments for the Chemical Industry class.
The testers: Anthony Best, Henry Brouwer, and Jordyn Tygesen, uncovered significant interactions of wind, water and lighting position on the burn time as illustrated by the Pareto chart of effects from Design-Expert software.
I expect these three experimenters will be enjoying extremely sparkly celebrations this summer!
Killer reveals contents of International Shark Attack File
Posted by mark in Nature, Uncategorized on January 26, 2021
I will bet the caught your attention. It did mine but for reasons more benign than indicated by my sensational blog title: The report comes from an outdoors columnist for Florida’s Treasure Coast Newspapers named Ed Killer. He passed along the latest statistics on shark attacks released Monday by the Florida Museum on Natural History. It turns out that “interactions” with these dreaded aquatic carnivores decreased by nearly 10% to 129 worldwide in 2020. Unfortunately, deaths increased to 13, up by 2 from 2019, including the first ever in Maine. Australia led the world for shark fatalities and came in second to the USA for bites.
“When a surfer gets bit in New Smyrna Beach [Florida], it’s often by a blacktip and requires some stitches to recover from. But when a surfer gets bit in Australia, it’s by a 2000-pound 15-foot-long great white shark. A nibble from a white shark can take off a leg.”
– Gavin Naylor, Director, Florida Program for Shark Research*
All this talk about sharks makes me feel a lot better being homebound in Minnesota for the time being. In 1975 my wife and I moved to California just in time for the premier of Jaws at the local drive-in movie theater. I suffered twitchy-legged nightmares for some time afterwards imagining a great white shark lurking at the foot of my bed. Watching this Danish advertisement provides an antidote my now-revived shark fears.
*See details on the data science behind their The International Shark Attack File (ISAF), and a fascinating animated graphic showing attacks by location worldwide over 50 years, here.
Experiment reveals secret to maximizing microwave popcorn—Part two: Results
Posted by mark in pop, Uncategorized on January 3, 2021
Nothing beats microwave popcorn for snacking. That’s what makes unpopped kernels (UPK) so aggravating—not just for the loss of yummy yield, but also for the pain from accidentally biting down on them. Therefore, I am quite pleased to report significantly reduced UPK discovered by my designed experiment detailed in part 1 of this blog.
The big reveal comes from the interaction plot showing that the effect of preheating depends on the timing method.
First off, look up at the upper left of the graph and notice that the default GE timing, done by a humidity sensor, creates significantly greater UPKs—the lower end of the least significant difference (LSD) bars (p<0.5) fall above the higher ends of all other LSDs. The actual results using my GE microwave popcorn button, shown by the red (no preheat) and green (yes-preheat) circles on the left, ranged from 41 to 92—far too many UPKs per bag.
Next, see how the combination of GE++ (adding time) with no preheating wins out overall. The actual counts, shown by the red circles at middle bottom, ranged from 23 to 34—far fewer UPKs than before.
Life is good: Best not bother to put in 1 cup of water and wait for a minute; also, no complications introduced by setting up my cell phone, quieting the household, and standing by to turn off the microwave when alerted by Popcorn Expert. All I need to do is press the popcorn button and then 9 twice for the extra time. Easy! And, by the way, the popcorn tastes great—no burning!
I never would have made this significant improvement without the more-precise:
- measurement of UPK counts (versus weight) and
- Poisson-regression (versus ordinary least squares) modeling*
*(available in the newly released version 13 of Design-Expert® software)
I encourage you to do your own microwave popcorn experiment, ideally multifactor ones using Design-Expert version 13, now available as a free, fully functional, 14-day trial. Many factors can be tested—first and foremost being brand of popcorn and time in the microwave. Two ‘hacks’ posted to the question-and-answer website Quora intrigue me:
Another hack botched by me (as confessed in part 1) is pouring the popcorn into a vented microwave container. Throw one or more of these factors into your design of experiment (DOE) and please let me know the statistical outcome along with the raw data.
I remain a few dozen kernels short of the perfect microwave popcorn: Zero UPK with every exploded morsel being incredibly delicious.
Every once in a while, someone will mail me a single popcorn kernel that didn’t pop. I’ll get out a fresh kernel, tape it to a piece of paper and mail it back to them.
Orville Redenbacher
Experiment reveals secret to maximizing microwave popcorn—Part one: Setup
Posted by mark in design of experiments, Uncategorized on December 27, 2020
Energized by a new tool in Design-Expert® software (DX) for modeling counts (to be discussed in Part 2—Analysis of results), I laid out a design of experiment (DOE) aimed at reducing the number of unpopped kernels (UPK) from microwaved popcorn. I figured that counting the UPKs would be a far more precise measure of popcorn loss than weighing them, as done in this prior study by me and my son Hank).
My new experiment varied the following two factors in a replicated, full, multilevel, categorical design done with my General Electric (GE) Spacemaker microwave oven:
A. Preheat with 1 cup of water at 1 minute on high, No [L1] vs Yes [L2]
B. Timing, GE default [L1] vs GE++ [L2] vs Popcorn Expert app [L3]
I tested the preheating (factor A) before and found it to be unproductive. However, after seeing it on this list of microwave ‘hacks’, I decided to try again. Perhaps my more precise measuring of UPK might show preheating to be of some help after all.
The timing alternatives (factor B) came about when I discovered Popcorn Expert AI Cooking Assistant for systematically applying the #1 hack—the two-second rule: When this much time passes between pops, stop.
By the way, I also tried the third hack—pouring the popcorn into a covered glass bowl, but that failed completely—causing a very alarming “SENSOR ERROR”. It turns out that the GE Spacemaker uses humidity to determine when your popcorn is done. The plastic cover prevented moisture from escaping. Oops! Next time I try this it will be with a perforated lid.
While researching the user manual for the first time since buying the Spacemaker 15 years ago (engineers rarely read instructions) and learning about the humidity angle for the first time, I also found out that pressing 9 twice after beginning the popcorn cook added 20 and then 10 more seconds (++) at the end.
The original experiment-design of 12 runs (2×3 replicated) was laid out in a randomized recipe sheet by DX, all of them done using 3 ounce bags of Jolly Time, Simply Popped Sea Salt microwave popcorn. Due to a few mistakes by the machine operator (me) misreading the run sheet, two extra runs got added—no harm done: more being better for statistical power.
Part 2 of this two-part blog will delve into the analysis details, but it became readily apparent from a one-to-one comparison that the default popcorn setting of my GE microwave came up far short of Popcorn Expert for reducing UPK. However, the “++” adjustment closed the gap, as you will see.
To be continued…
Moving averages creating coronavirus confusion
Posted by mark in Uncategorized, Wellness on October 26, 2020
The statistics being reported on Covid-19 keep pouring in—far too much information by my reckoning. Per the nation’s top infectious disease expert, Dr. Anthony Fauci, I focus on positivity rates as a predictor of the ups and down of the coronavirus. However, the calculations for even this one statistic cause a great deal of controversy, especially in times like now with rising cases of Covid-19.
For example, as reported by The Las Vegas Review-Journal last week, positivity rates for the Nevada now vary by an astounding five-fold range depending on the source of the statistics. It doesn’t help that the State went from 7-day to 14-day moving averages, thus dampening down an upsurge.
“We’re trying to get that trend to be as smooth as possible, so that an end user can look at it and really follow that line and understand what’s happening.”
State of Nevada Chief Biostatistician Kyra Morgan, Nevada changed how it measures COVID’s impact. Here’s why., The Las Vegas Review-Journal, 10/22/20
My preference is 7 days over 14 days, but, in any case, I would always like to see the raw data graphed along with the smoothed curves. The Georgia Rural Health Innovation Center provided an enlightening primer on moving averages this summer just as State Covid-19 cases spiked. Notice how the 7-day averaging takes out most of the noise in the data. The 14-day approach goes a bit too far in my opinion—blunting the spike at the end.
I advise that you pay attention to the nuances behind Covid-19 statistics, in particular the moving averages and how they get shifted from time to time.
PS My favorite method for smoothing is exponentially weighted moving averages. See it explained at this NIST Engineering Statistics Handbook post. It is quite easy to generate with a simple spreadsheet. With a smoothing constant of 0.2 (my preference) you get an averaging similar to a moving average of 5 periods, but it is far more responsive to more current results.
Engineer detects “soul crushing” patterns in “A Million Random Digits”
Posted by mark in Basic stats & math, Uncategorized on September 27, 2020
Randomization provides an essential hedge against time-related lurking variables, such as increasing temperature and humidity. It made all the difference for me succeeding with my first designed experiment on a high-pressure reactor placed outdoors for safety reasons.
Back then I made use of several methods for randomization:
- Flipping open a telephone directory and reading off the last four digits of listings
- Pulling out number from pieces of paper put in my hard hat (easiest approach)
- Using a table of random numbers.
All of these methods seem quaint with the ubiquity of random-number generators.* However, this past spring at the height of the pandemic quarantine, a software engineer Gary Briggs of Rand combatted boredom by bearing down on his company’s landmark 1955 compilation of “A Million Random Digits with 100,000 Normal Deviates”.**
“Rand legend has it that a submarine commander used the book to set unpredictable courses to dodge enemy ships.”
Wall Street Journal
As reported here by the Wall Street Journal (9/24/20), Briggs discovered “soul crushing” flaws.
No worries, though, Rand promises to remedy the mistakes in their online edition of the book — worth a look if only for the enlightening foreword.
* Design-Expert® software generates random run orders via code based on the Mersenne Twister. For a view of leading edge technology, see the report last week (9/21/20) by HPC Wire on IBM, CQC Enable Cloud-based Quantum Random Number Generation.
**For a few good laughs, see these Amazon customer reviews.