Archive for category science
Tiny rotifers defeat the Red Queen
This week’s NPR Science Friday presented a fascinating report on rotifers, also known as “wheel animalcules”* due to the way they rotor food into their cylindrical bodies.** Besides being so funny-looking, these critters are unique in being only female — no guys to bother with (a bit of a bummer coming up as we are to Valentine’s Day). According to the Red Queen hypothesis this single gender situation should have put rotifers at an evolutionary disadvantage. However, these animalcules manage to thrive, albeit plagued by parasites. They survive by tolerating dehydration for amazing-long periods while riding the wind to their next home – typically a single drop of water.
Check out this entertaining Science Friday video on rotifers, which features new research by Paul Sherman and Chris Wilson of Cornell University. Warning: Although this production would be rated “G” for gender, it may not be suitable for children due to some horrifying imagery of lethal fungal parasites.
*Detailed in Welcome to the Wonderfully Weird World of Rotifers
**Seen in the brief video Life in a Drop of Water: Rotifer
Apples and oranges comparison of diets?
Posted by mark in science, Uncategorized, Wellness on January 21, 2010
While exercising on my elliptical machine this morning watching ABC’s Good Morning America the show captured my attention with a report that Weight Watchers (“WW”) this week filed a lawsuit against one of its top competitors, Jenny Craig (“JC”). The dispute stems from a claim by JC that their clients lost, on average, over twice as much weight as those on the largest weight loss program. WW alleges that this claim is deceptive due it comparing a study by JC done this year versus one done by WW 10 years ago. According to this news release by Weight Watchers the complaint states that generally accepted standards of biomedical research require Jenny Craig to compare the two current offerings of both companies through a head-to-head randomized clinical trial.
“You can’t compare studies that were done in different locations at different times using different groups of people.”
- Louis Aronne, M.D, New York Presbyterian Hospital weight loss expert and author of Eat This, Not That
Although the judge has put a temporary restraining order against their offending ad, I wouldn’t rule out the JC claim prima facie. After all, as Smartmoney Magazine writer Angie Marek stated in her column on The Skinny on Big, Fat Diet Programs “the science on most of these plans is hardly conclusive, since most of the research has been paid for by the diet companies themselves.” In fact, I predict that this case will keep at least two statisticians fat and sassy as expert witnesses (one on each side of this tug-of-war).
Atlantic claws coming to town this Christmas
I came across this unusually bold crab a few weeks ago while beach-walking in Florida.
Perhaps the size of this creature is explained by findings of marine geologist Justin Ries of the University of North Carolina, who reports that rising levels of atmospheric carbon dioxide may lead to larger crabs, shrimp and lobsters.
See a summary of Ries’s research and a picture of a monster lobster in this post by NPR. Wow, these exoskeletoned creatures really like carbon!
PS. All this talk of large lobsters reminds me of an illustration of evolutionary operation (EVOP) by Box and Draper.* Their process improvement method calls an ongoing series of two-level factorial designs that illuminate a path to more desirable manufacturing conditions. I will talk more about this in a future blog.
*Box, G. E. P. and N. R. Draper, Evolutionary Operation, Wiley New York, 1969. (Wiley Classics Library, paperback edition, 1998.)
Running hot and cold in Apalachicola – steaming to cook clams and steaming to make ice
My wife and I are celebrating our 35th anniversary with a Thanksgiving week getaway on the panhandle of Florida. Later today we will enjoy a southern version of the traditional banquet, this one will featuring all sorts of grits – the chef’s specialty. I expect some oysters too – mainly harvested just down-beach at Apalachicola. Also, at the local Piggly-Wiggly I noticed lots of sweet potato pies laid out, along with pecan pies, of course. If I lay off the grits, maybe I will keep some room for a piece of the pecan pie, preferably with some whipped cream on top.
Earlier this week we stopped by an interesting museum in Apalach’ (as the locals refer to it). It celebrates the achievements of a local physician, John C. Gorrie, who invented the ice-making machine. He is also considered to be the father of refrigeration and air conditioning. Obviously the folks here in Florida hold Dr. Gorrie in high esteem for his dedication to cooling things off. What interests me, being that I am a chemical engineer, is how steam powered Gorrie’s ice machine. That seems very counter-intuitive, but the thermodynamics are explained nicely here by the inventor:
“If the air were highly compressed, it would heat up by the energy of compression. If this compressed air were run through metal pipes cooled with water, and if this air cooled to the water temperature was expanded down to atmospheric pressure again, very low temperatures could be obtained, even low enough to freeze water in pans in a refrigerator box.”
For a picture of what he patented in 1851 and historical background, see this Wired magazine article by Randy Alfred.
Getting back to the Thanksgiving feast this afternoon and thinking about the oysters, I suppose we will be given a choice of raw ones laid out on ice (thanks to the local inventor) or one cooked with steam. Coming from the middle of our continent, it may be too much of a stretch to eat uncooked shellfish. In fact, it makes me a bit queasy just thinking of it. Although I fancy myself an experimentalist, sometimes I must draw a line in the sand.
PS. One thing I find curious is that the oystermen (sorry ladies) still do their harvesting the old-fashioned way with tongs – see this video, for example .
Statisticians do not see global cooling trend
This story by Seth Borenstein, AP Science Writer, is sure to create a lot of heat from those who dispute global warming. Without revealing what the numbers represented, his news organization gave temperature data to four independent statisticians and asked them to look for trends. They found no evidence of any decline – only a long-term increase over the last 130 years, thus taking away fuel for the fire that the world is now cooling.
I like the idea of this being a blind analysis, although I wonder if these four statisticians might’ve seen through this. Also, what is a good sample size for statisticians? Four seems meager. Do you pick statisticians at random, or what?
Anyways, I am more concerned about my Minnesota Gophers going to a new outdoor stadium in what will turn out to be one of the coldest Octobers ever in this region. They play Saturday night, which is Halloween – scary enough on a college campus –but it might be wickedly cold as well. Fortunately I have a good collection of Gopher shirts, sweats and jackets to put on layer-by-layer. I noticed something funny about being outdoors after so many years of under the Metrodome: People clapping with mittens on just doesn’t work as well for cheering purposes.
NASA shoots the Moon
I got up a bit earlier than usual to set up my 8-inch reflector telescope for a view of the 6:31 AM CDT collision of NASA’s Lunar Crater Observation and Sensing Satellite (LCROSS). The weather was ideal – clear skies with no wind. Never mind that we had our first frost – Minnesotans like me don’t mind temperatures at the freezing point (knowing full well that soon this will be considered balmy!). However, despite a spectacular view of the Moon’s South Pole, I saw no evidence of the “man in the moon” getting ‘goosed.’ To placate the alarmists who thought the Moon might be destroyed, NASA likened their crash to an eyelash hitting a jetliner. From what I could see myself and the video by NASA, that is an apt analogy, assuming the eyelash came off a gnat.
So LCROSS proved to be a lot less dramatic than us skywatchers hoped for. However, if the follow-up satellite sensed water blown up by its self-destructive predecessor, the mission will be a big success. This will take a while to decipher as noted by Wired magazine’s GeekDad blogger Brian McLaughlin. If you are geeky like me, you will keep an eye out for the final outcome of this shoot-for-the-moon experiment.
PS. All this is mindful of the book by Jules Verne From the Earth to Moon posted with illustrations from an 1886 edition by NASA in their Space Educators Handbook
(“One small click for all mankind.”). It’s fantastic!
Math messed with future astronaut’s mind and made him think faster
Last Thursday I enjoyed an inspirational speech by USAF Lieutenant Colonel Duane “Digger” Carey – a Saint Paul guy like me, but one who went far further than possibly any other from our home city. Digger was invited by the University of Minnesota’s Institute of Technology to speak about his experiences as pilot of the Columbia Space Shuttle mission of March 1-12, 2002,* that successfully upgraded the Hubble Space Telescope.**
Although Digger has many stories to tell, not the least of which is his record as a combat fighter pilot, he is most passionate about the benefits of math and science. He feels that his Masters in Aeronautical Engineering, while not directly relevant to flying a jet, enabled him to solve mission-critical problems at afterburner speed.
It was great seeing a hero like Digger Carey talk up math and science to our young people. I recall taking a summer physics camp and working out the equations for rocketry while building a model of the Saturn V. At the end of the course we blasted it off with 5 solid-propellant engines. Unfortunately it went way up and out of sight, so we never recovered the parachuted parts that floated somewhere back to Earth. However, even if we’d found the rocket, there would be no way to recapture the joy of seeing math and science put into action on that first launch. Anyways, that was enough for me. Imagine actually being inside a rocket blasting off! That takes a lot of courage and faith in technology.
“The most important thing we can do is inspire young minds and to advance science, math and technology education.”
– John Glenn, one of NASA’s original astronauts
* The last mission before the disaster of 2003
**See these spectacular new images from Hubble produced by the space telescope after the latest (and likely last) upgrade made by Shuttle Discovery astronauts who just landed Friday.
Coriolis effect continues to make the rounds despite efforts to flush it down the drain
Upon hearing a travel report from an acquaintance spending time this summer in Ecuador, I could not resist asking her to observe which way her sink and toilet drained. I’d heard that, due to the Coriolis effect, when you flush water in the northern hemisphere it swirls one way (clockwise), but below the equator it goes the opposite way.* Here is her enthusiastic report:
“Hi Mark, Yesterday I tested it – it´s true! We went to the Mitad del Mundo (Centre of the World), a big monument where the equator line is supposed to be. Unfortunately, they made a mistake when measuring, so the real equator line is a five minute walk away from the monument. By the real line they built a museum and there you can do funny experiments. For example, they put a sink on one side of the equator and let the water flush down, and then they move it to the other side and the water flushes the other way. On the line itself the water just goes straight down – no kidding! It was very interesting!”
I then had to do some research to see if this phenomenon could be independently verified. I hate to be a party pooper (ha, ha!), but, from what I read, in reality the Coriolis effect is so small that it’s easily overwhelmed the shape of the bowl and the other factors. Thus, most toilets flush in only one direction — clockwise or counterclockwise — regardless of location. This is explained very nicely by Alistair B. Fraser, Emeritus Professor of Meteorology Pennsylvania State University, in his white paper on Bad Coriolis.
In any case, it is fascinating to watch the last gallon of water from a hot bath twirl down the drain, so why not observe whether it exits clockwise or counter? I’ve never been south of the equator myself – the nearest I came was in Singapore. My hope is to do some personal validation on the Coriolis effect, or lack thereof. Why not?
*In a memorable episode (I thought it extremely funny) of the television cartoon The Simpsons (16th one in the 6th season), Bart, purporting to be an official with the “International Drainage Commission,” convinces an Australian boy to do a similar ‘down-under’ experiment. The results proved inconclusive, but very humorous. 
Does good experimental design require changing only one factor at a time (OFAT)?
Posted by mark in design of experiments, science on June 23, 2009
“Good experimental design usually requires that we change only one factor at a time” according to an article I read recently in The Scientist magazine (“Why Don’t We Share Data,” page 33, Issue 4, Volume 23). This guide for science fairs tells students that “you conduct a fair test by making sure that you change only one factor at a time while keeping all other conditions the same.”
Obviously changing two variables together makes no sense, such as the time that as science project one of my kids asked me to do a blind taste test on Coke versus Pepsi, but to keep them straight in their mind, she poured one cola in blue plastic cup and the other in white Styrofoam! Needless to say I was completely confounded.
The OFAT method is so engrained that it’s literally become the law according to scientist who told me that, when as an expert witness he presented statistically significant evidence, it was thrown out of court due to the experiment design having changed multiple factors simultaneously. What a crime!
Multifactor testing is far more effective for statistical power, screening efficiency and detection of interactions. Industrial experimenters are well-advised to forget their indoctrination in OFAT and make use of multifactorial designs. For reasons why, see my two-part series on Trimming the FAT out of Experimental Methods and No-FAT Multifactor Design of Experiments.
Good experimental design does NOT require changing only one factor at a time!
Inverse transformation puts mileage comparisons on track
Tomorrow the IRS adds 8 cents per mile to their allowable rate for deductions on automobile use for business purposes. Precipitated by the rapid rise in fuel prices, this is an unprecedented mid-year boost of over 15 percent from the previous rate of 50.5 cents per mile.
When the price of gas went over 4 dollars a gallon, I started paying attention to which of my three cars went where. For example, my wife and her sister traveled 100 miles the other day to do some work at the home of their elderly parents. They had our old minivan loaded up, but, after thinking about it getting only about 15 miles per gallon (mpg), I moved all the stuff over to my newer Mazda 6 Sport Wagon, which gets 25 mpg. That meant no zoom-zoom for me that day going to work, but it was worth enduring the looks of scorn from the other road warriors.
A few weeks ago, National Public Radio’s All Things Considered led off with this quiz: “Which saves more gas: trading in a 16-mile-a-gallon gas guzzler for a slightly more efficient car that gets 20 mpg? Or going from a gas-sipping sedan of 34-mpg to a hybrid that gets 50 mpg?” Of course the counter-intuitive answer is the one that’s correct – the first choice.
This is a “math illusion” studied by Richard Larrick, a management professor at Duke University. According to a recent article in the journal Science, Larrick found it easy to fool college students into making the wrong choice in puzzlers like that posed by NPR. He suggest that it makes far more sense to report fuel efficiency in terms of gallons per 10,000 miles — an average distance driven per year by the typical USA car owner. Most of you who are likely to read this blog can easily apply this inverse transformation on mpg, but to check your math see this table posted by Duke University’s Fuqua School of Business.
According to this report by Reuter’s Professor Larrick was inspired to promote “gpm” (vs mpg) after realizing in the end that he’d be better off trading in the family minivan and only gaining 10 miles per gallon with a station wagon; rather than swapping his second car, a small sedan, for a highly efficient hybrid. This must be the basis for the NPR’s quiz.
This is definitely an issue where all things should be considered, but most importantly, just how much gas money might be saved one way or the other. Do the math!
PS. News flash: You can rest easy tonight – there will be no leap second, positive or negative, according to this post by the Time & Frequency Division of the National Institute of Standards and Technology (NIST).
