Wednesday, April 29, 2020

You can play with Real Dough as well! Sweet Bread Snails!

Who knew you could play with real dough just as well as the toy variety?

My son called my Sweet Hawaiian bread "boring", so he helped make it more interesting. Notice the eyestalks! I started making spiral buns and he decided some of them needed bodies to become snails!

This is the recipe from a few weeks ago (link) on this blog, with the exception that the recipe was made more flavorful:

* Fresh grated ginger increased from 1 teaspoon to 1 tablespoon
* 2 tsp. of ground Cardamon added

Otherwise they are the same as before - though we forgot to brush them with egg whites before baking, so the crust isn't shiny.

Have fun!

Tuesday, April 28, 2020

City Lights and Spectroscopy

Ever look out at the city at night wondering what the technology behind the glittering lights might be? I do...

Turns out there is a simple way to find out what is making the light. This picture was taken through a 1000 lines-per-millimeter diffraction grating (the cheap kind from Rainbow Symphony that come in a 35mm slide frame). I placed it in contact with the camera case and parallel to it, then adjusted the rotation of the grating until the spectra were generally directly over the light source creating them.

The verdict?

This view of Los Angeles has a remarkable diversity of lighting technologies on display. One to the left of center stands out to me, as unlike most of the spectra in view (which are continuous stripes of color), this one is made from distinct spectral lines (not all colors of the rainbow are present).

Line Spectra are like fingerprints for atoms and molecules: the light is made of just a few select colors at characteristic wavelengths. Each line relates to a very specific transition in the orbiting electron clouds of specific atoms. In many cases the complete list of elements in a sample can be teased out of a careful examination of the spectrum.

The temperature of the plasma (assuming the emissions are coming from an electrically charged hot gas, as in a mercury vapor or sodium vapor light) can also be determined by understanding how much energy is released in each transition. There is a simple relationship for the average kinetic energy of atoms moving in a gas and their temperature:

K = (3/2)*(R/N)*T = (1/2)*m*v*v

Note that R=8.314J/mole-K, N=6.022x1023 particles/mole, T is temperature in Kelvins. K is the average kinetic energy of the atoms moving in the gas, with m being the mass of a given atom, and v being the root-mean-squared velocity of the atom.

There are several good sites discussing the kinetics of gasses. NASA has a nice one where you can select your grade and the material is selected appropriate to your grade level. See

A variant of this thinking lead to Einstein's first Nobel Prize, which is for the Photoelectric Effect (light striking a metal causes no emission of electrons if the photos are below a certain energy, while above this threshhold the energy of the electrons emitted increases with increasing photon energy).

Incidentally, this is where "Absolute Zero" comes from - at Zero degrees Kelvin, all motion stops. (there are semantics about whether spreading of wavefunctions via the Heisenberg Uncertainty Principle amounts to some form of motion, for example).

We were just looking at pretty colors, right? Turns out it is a great entry point to explore some amazing physics and how our universe works.

Tuesday, April 21, 2020

Finding the Bats in Los Angeles

Ever try to find something that is dark, at night, that flies fast and in anything but a straight line?

I can think of a dozen ways to find them - the way just described does not top the list.

This evening after sunset I went looking for bats. I installed a bit of software on my cell phone called "Physics Toolbox Apps" by Vieyra Software (Disclaimer: I have no ties to these folks, no vested interest, and no contact). It reads data from the sensors built into the phone and presents it (as well as saves data files conveniently in ".csv" format) graphically.

One of its tricks is to process inputs from the microphone and perform what I presume is a Fast Fourier Transform. This takes the signal and transforms it into the frequency-intensity plane (among other things). The result is a picture of the soundscape showing the audio spectrogram over time.

Bats often echolocate with very fast chirps at 18kHz and above. You can see a bunch of fast, faint pulses from a distant bat at the top of this plot, around 22kHz (they are faint and about ten per second, horizontal dashes on the right edge of the picture):

Another species of bat came by at a slightly different time, producing chirps lasting tens of milliseconds every half second or so, with broad intensity between 20kHz and 24kHz (the upper limit is the upper limit of my sensor). These are the horizontal dashes on the right side of this image:

While these may not be National Geographic cover material, they do beat my best photo using visible light of a bat (I cannot find it myself - it was near center of the frame, but likely was moving too fast for this exposure):

My son was with me when these were taken, and he didn't need the phone spectrogram to find bats - he could hear the chirps and got fairly good at pointing at the bat, which would occasionally become visible when backlit by the twilight sky. "Sometimes one was a clicking sound almost, and the other was like a high-pitched squeak sound".

Edit: Turns out this obvious approach has been used for quite some time and has been reduced to a science. I have no ties to these sites, and find them very helpful.

The USGS (United States Geological Survey)has a great document called "Identifying Bats by Sound" at

The USGS has a great document on how to establish workflows to process acoustical data on bats called "A Guide to Processing Bat Acoustic Data for the North American Bat Monitoring Program" at 

If you want to identify the bats to species, there are several online resources

Sunday, April 19, 2020

Victory Garden on a Balcony: Starting Nasturtiums

We happen to have a balcony or two. One of them has a south-west exposure and one a less well illuminated exposure. We've been gardening on them since they are "easy access" in essentially all weather conditions.

While this means some plants never reach full size due to being eaten by some family member when they are tiny (all Peas, for example, appear to be isomorphic with Snowpeas to certain family members and get eaten as soon as the pods are bigger than the flower they came from...).

Back to Nasturtiums!

For Easter one of the items our son found in his basket was a packet of Nasturtium seeds. These are awesome - they are widely tolerant of growing conditions, fast growing, pretty, and tasty.

Additionally, the seedlings look wild (at least if you start them in moist vermiculite in a plastic humidity chamber):

Right after germination the seeds can still be seen.

My son tells me "You need to mist them a lot and give them a good home."

To plant them, we got some sandpaper and sanded a smooth spot on each seed (just until the white shows a little). Then we soaked the seeds for an hour in cool water. Then we dumped the water into the sink and spread them out on moist vermiculite (you can use almost any sort of starting material) in a plastic tub that takeout came in (after a brief wash...). We put an inch of so of moist (not sopping) vermiculite and closed the lid.

The container was placed on the kitchen counter away from sunlight for about a week. The seeds we sanded to expose a bit of the white part inside the seed are the ones that germinated. The ones we did not sand but soaked and planted at the same time we are still waiting on.

Thursday, April 9, 2020

Sweet Hawaiian Rolls - baking our way out of cabin fever

Today is another "remain at home" day, along with pretty steady rain - not even getting a walk today. What to do? Bake!

Here is the recipe, which is a merging of several different recipes we found online (I lost my notes - apologies!).

We used a bread machine to do the kneading of the dough.

Into the tub we placed:

  • 0.5 cup orange juice (pasteurized)
  • 1 tablespoon of instant dry yeast
  • 1/4 cup light brown sugar
  • 1/4 tsp Stevoside (the really, really strong powdered Stevia)
  • 1 teaspoon vanilla paste
  • 2 large eggs
  • 1 extra egg yolk (set the white aside - you need it later to brush the rolls before baking them)
  • 1/4 cup water
  • 1 teaspoon of freshly grated ginger root (peel, then grate the peeled ginger)
  • 1/4 cup unsalted butter - ok to drop a part of a stick in so long as it is not frozen, it does not need melted if using a bread machine to knead the dough
Mix this up and let it sit until the yeast has woken up (some bubbles start to form, often takes 15 minutes at 68 degrees Fahrenheit).

Add 3 cups of all-purpose flour and 1 teaspoon salt. Turn on the bread machine to mix it. Eventually the dough will be sticky but not stick to the container that it is mixing in. If too wet, add flour two tablespoons at a time (roughly) and reknead.

Allow it to rise till doubled, then turn the oven to 350 F and put a sheet of parchment paper on a cookie sheet.

Knead the dough again.

I spray oil on the cutting board (polypropylene slab) and turn the dough out. I then oil my hands with canola oil and form the dough into a long even log. Cut it in half. Repeat with each half. Repeat with each quarter. Repeat with each eighth. Now you should have 16 evenly sized balls of dough.

Arrange the balls of dough on the parchment paper, then whisk the egg white and about the same amount of water.  Paint the top of each roll with some of the egg white mix.

Now wait. Wait a bit more. When the rolls are doubled in size, put them into the oven for 20 to 22 minutes - keep an eye on them, ovens can vary quite a bit.

When the color of the photo, pull them out and put on a cooling rack.