1/22/12

Daylight

Because I was up before sunrise and missing the sun, I got to wondering when it would rise.  One thing led to another and I graphed the sunrise and sunset times for 2012.

Two questions:

  1. Why isn't it symmetric about the date or time axes?
  2. What are all the discontinuities? 

Inquiring minds want to know.  In any event, it seems I'll be up before sunrise for another month and a half, sadly.

8/16/11

How to create a reviewable, scientific document, in html-compatible format

Though not the only way, this is a working method for creating a document written in html-compatible code.
  • For equations:  Download "Math Cast" and create your equation.  Your saved file can be opened in a text editor to grab the html code.  (It is actually MathML, but will work in html editors.)
  • For images (of diagrams, apparatus, etc.):  Upload your image to flickr.com.  Once uploaded, the image has its own web address and html code.  Use the "share" option to grab the code. 
  • For text:  Just type!  Use a text editor.  Insert your equations, diagrams and images using the grabbed code previously discussed.
For LaTeX junkies, all of this can be done with WinEdt or a similar TeX editor.  There is a steep learning curve, but the results are stunning. Why use LaTeX instead of Word or similar?  Two "words":  html code.  You *can* get html out of Word, but it contains a bunch of extraneous gobbletygook that is inevitably buggy and cumbersome.  

If you want to share your document in html, use the method in this post (or LaTeX, for more formal, "camera-ready" documents).

8/15/11

What's in your document?

Awhile back, I posted about how to insert equations into google documents.  The link I blogged about is no longer functioning so I needed to find another way, and a better way.  A way to insert equations that aren't images only, but editable pieces of information that flow seamlessly into a document. 

I haven't.

There is some interesting information out there regarding the paucity of html-compatible mathematical and scientific communication.  I'm running into it because of a calibrated peer review project I'm part of at Stout.  I wanted to enable my students to post real homework solutions for other students to review.  The sad thing I'm finding is that it is easier for them to hand-write a solution, scan it into a digital PDF document, post it to flickr or similar as an image and link to the uploaded image!!!

Where are digital chalkboards when you need them?  We have those, you say.  Yes, we do.  But, trying to share what you've written with anyone on the web is difficult, unless you are sharing an image.  Why can't we share scientific writing like we can share text?  Something editable by groups, easily typeset, etc?

I'm calling it.  Whoever develops this technology will be a physicist.  And it will revolutionize communications and networking yet again.  Web 4.0, that's my prediction.  A system that would allow communication in this way would not just be for scientists, mathematicians and engineers.  If you can draw a diagram, you can also collaboratively share artwork, photography, logos, anything you can scrawl into the sand, or paint on a wall.

Ok somebodies, get to work, please.  We educators are waiting on you.

5/31/10

Yoga Foam

I enjoy yoga. At right is a closeup of a section of my very first yoga mat. It came as part of one of those kits, with the DVD and everything, that you find in your local discount store.

As a materials person, I am intrigued by this structure. I thought I'd share it here.

This mat is probably PVC, wholly or in part. PVC stands for polyvinyl chloride. It is a thermoplastic polymer, a type of plastic. PVC in itself is non-toxic. Without additives, it has the feel of vinyl siding on houses. Many of the PVC products, however, have been softened with the use of plasticizers called phthalates. Phthalate is toxic to humans and other critters. It outgasses for awhile after the softened PVC has been manufactured. (That "new car smell", for example.) Most plastics manufacturers have ceased using phthalates in PVC construction. If you're concerned, ask about the additives used.

All that is well and good to know. However, I always like to find out the microstructure of these beasties. It is fascinating to me to think how the tiny structure has emergent properties at higher levels of complexity. In other words, a monomer molecule of PVC ain't nothing like the real thing, baby.

The aforementioned monomer is a carbon atom with 3 single bonds to hydrogen, and one to chlorine. But there is so much more!

When you get a bunch of these puppies together, they form chains of inert molecules. Multiple chains conglomerate like spaghetti noodles in a bowl. The ability of the chains to slip past one another accounts for the softness/hardness of the material. You can do stuff to change the hardness. Raising the temperature makes it soft. Lowering, hardens it. But there is yet more!

If you bubble the clumps of chains by blowing air through them (think blowing bubbles in your drink with a straw, but with 10 x the force and an 100 x smaller straw), you can create plastic bubbles! Tiny bubbles, everywhere. Like the foam on a glass of milk, the bubbles in plastic form their own structure, depending on a host of factors.

Plastic bubbles don't collapse as liquid bubbles do. Plastics are, after all, not liquid at room temperature. However, they do reshape over time. New bubbles are roundish. Established bubbles are polygon-shaped. Foam is born.

I'm no plastics engineer, but I find this stuff fascinating. Somebody figured out how to blow bubbles in PVC to form foams that stay foamy! Like the yoga mats in their original incarnation. Current mats are made of many different materials, not all of which are plastics.

Next time I'm doing a down dog, I will no doubt be looking at a spot on my mat like the one shown, imagining blowing bubbles in my spaghetti that stay!

It is great to be a geek.

6/12/09

Equations in docs

Doing Math and Physics Collaboratively using Google docs


You can use this equation maker (a LaTeX style editor) to create gif files


and paste them into Google docs, like the one above.

Steps: 

  1. Go to thornahawk.unitedti.org/equationeditor/equationeditor.php.
  2. Click the boxes to create your equation. 
  3. Click "Render Expression".
  4. Right-click on your equation that appears, and select "View Image".
  5. The image appears in a new web page.
  6. Copy the url from that page.
  7. Go to a Google doc you're working on. 
  8. Click "Insert" and select "Image". 
  9. In the dialog that opens, select "From the web (URL)".  Paste the URL into the provided line.
  10. Click OK.
  11. Voila!



3/8/08

Aunt Amy's Hot Butterscotch Pecan Cinnamon Rolls

The recipe for these rolls is famous in my family. It was created by my aunt Amy. This picture was my attempt at making a plain version of them. They are much better when she makes them! It is said that once in front of you, there is no resisting them, no matter how many you've already had! Here's her recipe:

1 cake fresh or package granular yeast
1 cup lukewarm milk
1/4 cup sugar
1 teaspoon salt
2 well-beaten eggs
3-1/2 cups flour
1/4 cup melted shortening (part butter for flavoring if possible)


  1. Mix dough as for bread, i.e., let it rise once.
  2. Roll to rectangle 1/4 inch thick and twice as long as it is wide. Then brush rectangle with soft butter, sprinkle with 1/4 cup (white) sugar mixed with 1 teaspoon cinnamon. Roll out and pinch to seal.
  3. Place 1-inch slices in this mix: Melt 2 Tablespoons butter, add 1/2 cup brown sugar, 1/4 cup dark corn syrup. (Can use white corn syrup.)
  4. Heat to dissolve sugar and let cool.
  5. Sprinkle with 1/2 cup pecans, 1/4 cup raisins (optional).
  6. Place rolls in 9 inch square or round baking pan. Let rise about 30 minutes. Bake in moderately hot oven (375 degrees) 25 to 30 minutes.
  7. Turn on to rack or cookie sheet.

    Skid Control

    For those of us who learned to drive in sub-tropical climates, here's a physics professor's take on how to avoid spinning off of an iced road:

    If you turn in the direction you want to go while sliding, you may notice that you continue to slide. Very disconcerting. The trick to getting out of the slide is to turn your wheels in the opposite direction you want to go. This can give you control back and avert continued sliding.

    Why does this work? Let's say I'm sliding to the left on a road going straight ahead. I frantically turn my wheels to the right, but I slide even more easily now... Imagine what the tires look like in the direction of slide. By turning them to the right to correct for the left-slide, you've put the tires perpendicular to the slide direction, preventing them from turning in that direction.

    Now let's try turning to the left to correct. Imagine the tires now. Their rotation axis is perpendicular to the slide direction, and thus the tire tread is free to rotate along the slide direction.

    If you're lucky, the tires will begin to rotate on the slippery surface, giving you a bit of traction back. It is the backward force of friction on the rotating tires that allows your engine to push the car forward, after all.


    Moral of the story: TURN INTO THE SLIDE!