Catenaries, Square Wheels, and Washboarding

      The square-wheeled bike at Macalester College in St. Paul, Minnesota, is the inspiration for this week's PEOTS. 

    

     Mom, Zoë, and I had fun riding the blue-wheeled trike along the catenary curves:

     It really is a smooth ride and one does not feel the bumpiness of a washboarded dirt road as the length of the squares' sides roll perfectly into the endpoints of the catenaries. It is intriguing that quarter circles were used to move large square blocks of marble around the pyramids.

       So all those jokes about square wheels really aren't quite as funny any more. . .

     Jan's questions about washboarding on dirt roads dovetails into our square wheel discussion:

     This article discusses why wash board ripples or corrigations form whenever a vehicle travels more than 5 miles (8 km) per hour over a gravelly or sandy surface. My best guess as to why they extend over the whole road is that drivers try to avoid existing ripples, thereby inevitably creating more right next to them. 

      The most mysterious part of the researchers' results is that the ripples appear even when the springy suspension of the car and the rolling shape of the wheel are eliminated.

       Letting some air out of tires when going over washboarded roads approaches traveling over catenary-like bumps with a square-ish tire.

         What other questions spring from square wheels, catenaries (which makes me think of a cat who ate the canary) and washboarded roads?

Sponge Steph, Square Pants

Blue Earth, Green Giant, and Tidings from Mac

      We are taking a detour from the traditional PEOTS meanderings to our return road trip from The Cities through southwest Minnesota:

     We had a great time in Blue Earth as Maizie frolicked beneath the giant's size 78 shoes.

     Of course, in all the cement arrow searchings, this was the definite highlight. Congrats to Zoe, Macalester Class of 2015. May your meanderings in Ethiopia be long, safe, and fruitful! 

        What a great, l o n g trip it's been! Thelma and Louise-ing it. . .

Very bittersweet moments here,
Steph

Road Tripping the Cement Arrows Fantastic and Ten Geologic Images

          Road tripping here in search of large cement arrows. ;-) Perhaps you can tell where Mom, Maizie and I have been from a few photos and knowing what time of year it is:

       And for this shortened week, enjoy Ten pictures that will "make you want to become a geologist."

     Checking my quiver carefully.

Enjoy,
Steph and Co

Century-Old Cat Tongue: Papillae-On

      I'm short on time this week so will present you with this link to a 100-year-old image of a cat's tongue in today's Science Friday :

      The text from the NPR Science Friday link is also reproduced below:

       "You’re looking at a 3 mm-wide section of a cat tongue more than a century old. David Linstead’s captivating image was a winner in this year’s Wellcome Image Awards.


       "The picture is actually a composite of 30 polarized light micrographs, or photographs taken with a digital camera and a microscope. A retired cell biologist, Linstead used microscopes professionally as a research tool, and later formed his “hobby addiction” after purchasing one, then another, and still more microscopes on eBay (also his go-to source for specimen-plated slides like this one). His particular interest is in combining modern illumination techniques with vintage slides dating from 1860 to 1910, the heyday of slide-making."

      “The original person who made this slide likely had no thought of how it would be used in 100 years’ time,” says Linstead, who estimates that it dates back to the 1890s. “But when I saw it, I immediately knew it had great potential.”

     "The promise lay in the way the slide was prepared. It wasn’t stained, for one, which allowed the cross-section’s true colors to be observed with polarized light—a feature of most cutting-edge microscopes of the Victorian age. Those yellow streaks, for instance, are horizontal muscles, and the sparse purple ones are muscles that run vertically."

      "Furthermore, the original tissue had been injected with a dye—probably a solution of iron salt in warm gelatin, Linstead surmises—to make the capillaries, seen here as black squiggles, apparent. (The only alteration Linstead made to the image was to Photoshop the background gray, because the original magenta “didn’t go well with the rest of the slide.”)"

      "Colors aside, the serrated ridge may be the most intriguing aspect of this picture. Those rough bumps, or papillae, are the reason that a kitty’s tongue feels like sandpaper when it licks you. When a cat grooms herself, the papillae

 act like a comb to remove dirt and loose hair. But they also serve a grislier purpose: rasping meat off of bones. Fluffy might look sweet, but Linstead’s striking image is a reminder that the cat napping on the couch is a fierce predator."

       The other 19 images in this year's Wellcome awards, including these specialized Purkinje brain cells, are also quite intriguing.

     Let me know what you think. . .Hoping the cat doesn't have your tongue, er, thumbs. 

     [With fond thoughts of Lego's Noosie.]

Digitally,

Steph

Purkinje cells showing well-defined organization:

Fluoride and Fluorite: First Change since 1962: Decreased Levels of Recommended Fluoride in Drinking Water by the United States

          On Monday, April 27, 2015, the U. S. Department of Health and Human Services decreased the recommended amount of added fluorite in drinking water to about half the original recommendation. It is the first change in the recommended amount since 1962.

       
          The main documented side effect to over-fluoridation is fluorosis, a condition marked by white marks on the teeth. There are proven great benefits to low fluoride amounts to decreasing dental caries. Most people in the U. S are already getting fluoride directly on their teeth in the form of toothpaste and dental rinses. The NPR link above notes some believe fluoridation at higher levels is linked to other problems including thyroid issues, skeletal fluorosis, and ADHD.

           Much of the western world has already eliminated or decreased fluoride amounts in water supplies. There are some areas of the world that have naturally occurring fluoride which is over 1.5 mg/l (See world map here.) The high fluoride levels are linked to types of granite with the naturally occurring fluorite mineral (the purplish mineral in the pinkish granite below):

           The mineral fluorite, CaF2, is a member of the halide sequence.

          And, of course, fluorite is the namesake poster child for fluorescence under ultraviolet light:

          I am curious to hear about your views on the fluoride controversy. What is yours? Surely, the decreasing of the acceptable level by half is significant. 

Going with the fluo,

Steph

Capitanian: A Sixth Major Extinction 262 Million Years Ago?

      One of the first things geologists learn about is the major extinction at the end of the Permian Period (and Paleozoic Era) 250 million years ago. 96 percent of all species died during that mass extinction.

       Now geologists have discovered new evidence that may point to another extinction during the mid-Permian, 262 million years ago, just 12 million years before the major Permian-ending event. An April, 2015, Geologic Society of America (GSA) paper (Lead author David Bond) notes that the "Capitanian" saw the extinction of 87% of all brachiopod species.

        The Capitanian was named 20 years ago based on research in tropical to sub-tropical areas in China and elsewhere and believed originally to be more localized. Newest research in northern Norway suggests that this extinction may actually be more global (though several dissenters have commented on the publication in the well-respected GSA paper).

      
          Dr, Bond et al  write that the Capitanian extinction was likely triggered by the eruption of the Emeishan Traps, located in the southwestern Chinese province of Sichuan. Volcanic eruptions release large amounts of carbon dioxide, causing ocean acidification. Seafloor oxygen depletion may also have played a role.

             The major shift after the acidification and oxygen depletion was from domination of brachiopods to domination by bivalves after the Capitanian extinction:

      Brachiopods and bivalves differ in the number of adducting muscles, the way they eat, in their very classification, and in the symmetry of their shells. The two shells of bivalves are mirror images of each other; they are not in brachiopods.

          So, why were bivalves better suited than brachiopods for life after the Capitanian? Any guesses?

Shellfishly (and sleepily),

Steph

Exquisite Dating Tool: Zircons as Indicators of Earlier Closing of the Land Bridge Between North and South America

          New research indicates that the connection between North and South America was created 13-15 million years ago rather than 3-5 million years as previously thought. The age of zircons was the main indicator of the much older closing age. Here's an image of a  zircon (greenish elongate diamond) in crossed nichols polarization:

           Zircons are crystals that form when magma cools. Newly-formed zircons contain some uranium, but no lead.  Therefore, any lead found in an old zircon must have originated in the radioactive decay of uranium. Thus, zircons are a favorite tool for dating in geology. (as well as dinner and a movie ;-)).

          Zircons found in streams in Colombia and Panama have dated the closing of the gap and formation of the "land bridge" at 13-15 million years.

           The biggest mystery is why animals, especially mammals like this racoon ancestor, 

Chapalmalania, 

did not make the mass movement across the land bridge until 3-5 million years ago (as seen in the fossil record). Perhaps the "land bridge" was more like a series of volcanos with shallow waters in between so it took ten million years for a solid, continuous land bridge to form. 

            This research was performed by Camilo Montes et al. This article also contains a link to terror birds (if you dare). [And a new terror bird species has just been discovered as reported on April 13, 2015.]

             Any ideas as to what was going on in the 10 million years between the possible closing of the North and South American continents and the mass mammal migration (say that 5 times fast!)?

Zirconly,

Steph

Yawn, Yawn, Yawn: Emotional Closeness in Wolves and Other Species

     Here's hoping this post will make you yawn. 

       Researchers at the University of Tokyo collected data to show that yawns among wolves are related to emotional connection between individuals. The stronger the bond-- the more likely the yawn. The research is discussed here.

        There's evidence of interspecies transfer when it comes to yawns as well.

      

       Savor the etymology of yawn:

c.1300, yenen, yonen, from Old English ginian, gionian "open the mouth wide, yawn, gape," from Proto-Germanic *gin- (cognates: Old Norse gina "to yawn," Dutch geeuwen, Old High German ginen, German gähnen "to yawn"), from PIE *ghai- "to yawn, gape" (cognates: Old Church Slavonic zijajo "to gape," Lithuanian žioju, Czech zivati "to yawn," Greek khainein, Latin hiare "to yawn, gape," Sanskrit vijihite "to gape, be ajar"). Modern spelling is from 16c.

       May your day have lots of  yawns with whatever species you encounter today.

Here's to many more yawns,

Steph

And, seen at the Smith President's House yesterday (not far from the river otters):

Slab Melting: Quite Continental!

       Plate tectonics theory has generally espoused that all continental crust, rich in silica, has been recycled. 

     Virginia Technical University geologists have published research today indicating some of that continental crust may actually be new or "juvenile" crust.

       Some of the type areas for this discovery are in Costa Rica and Panama:

The March 31, 2015, research includes this description of continental and oceanic crust:

     "The researchers used geochemical and geophysical data to reconstruct the evolution what is now Costa Rica and Panama, which was generated when two oceanic plates collided and melted iron- and magnesium-rich oceanic crust over the past 70 million years."

      "Melting of the oceanic crust originally produced what today are the Galapagos islands, reproducing Achaean-like conditions to provide the "missing ingredient" in the generation of continental crust."

     "The researchers discovered the geochemical signature of erupted lavas reached continental crust-like composition about 10 million years ago. They tested the material and observed seismic waves traveling through the crust at velocities closer to the ones observed in continental crust worldwide."

        The study continues "It raises questions about the global impact newly generated continental crust has had over the ages, and the role it has played in the evolution of not just continents, but life itself. 

        For example, the formation of the Central American land bridge resulted in the closure of the seaway, which changed how the ocean circulated, separated marine species, and had a powerful impact on the climate on the planet."

        Older names for continental and oceanic crust are SIAL and SIMA, respectively. Sial is a short for silica aluminum (or aluminum silicate) and sima is short for silica magnesium (or magnesium silicate). The sial is less dense than the sima. And now, researchers have shown that some of that sial is juvenile. 

SIAL LATER!

Steph




        

A Picture a Day Picnic: Down the NASA Rabbit Hole with the Pelican Nebula and Opals

     Today I discovered this "A Picture a Day" site from NASA. Today's post on the Powers of Ten includes an intriguing video moving away and inward from a picnic by the powers of ten. Each post includes extraordinary images and descriptions by astronomers.

          The past posts from the NASA site lead you down many a fascinating rabbit hole. Click on the "Discover the Cosmos" link at the NASA site to enjoy exploring!

           The March 4, 2015, image from the NASA site of pillars and jets in the Pelican Nebula is particularly striking:

          And this particular Rabbit Hole led me to the Rabbit Hole Mine in Black Desert, Nevada, (red pin below) near the Burning Man Festival site. Based on what I know about the Burning Man Festival, their proximity cannot be an accident!

          The Rabbit Hole Mine is rich in sulphur, alunite, cinnabar, gypsum and opal.

           The powers of ten may also provide a colorful journey from opals to nebulae . . .and back, via the rabbit hole.

            Let me know your favorite past image on the NASA site. . .and do enjoy your trip down the rabbit hole. Please--come back!

Enjoy the ride,
Steph