### Sick Kids: Shriners, IHOP, and the Austin Digg Community Help

On February 12th in Austin, TX, IHOP and the Shriners will be teaming up to raise money for the Shriner's Hospitals for Children. IHOP will be giving away free stacks of pancakes that day and inviting their customers to donate to Shriner's Hospital for Children.

Each year, the Shriner's hospitals attend to the medical needs of more than 125,000 patients. All of the patients are children with orthopaedic conditions, burn injuries of all degrees, spinal cord injuries and cleft lips and/or palates. And all of the medical procedures are provided free of charge!

And this year, the Austin Digg community is getting into the act also! Austin is a very tech oriented community that plays host to several hardware, software, and IT firms. So, this year, we're using digg to get the word out about free pancakes and a chance to give back to the community. If you are in the Austin area, please digg this article and send it to all your contacts. Then, please plan on eating some free pancakes on the 12th!

A map of all the IHOP locations is shown below. To show how involved digg users are in their communities, you can print the digg image out below and hand it to a Shriner with your donation that day. We'll tally up all the digg donations, and post the totals here!

Austin IHOP locations

View Larger Map

Anonymous said…
um, I thought the purpose of Pancake Day was to help celebrate Shrove Tuesday-the day before the Lenten season begins when people swear off eating animal fats (like butter) and have a hearty pancake feast. Problem is, Shrove Tuesday is on February 5 this year, so countless religioso's will not be able to partake and the Shrine will lose countless donations. Oops!

### Cool Math Tricks: Deriving the Divergence, (Del or Nabla) into New (Cylindrical) Coordinate Systems

The following is a pretty lengthy procedure, but converting the divergence, (nabla, del) operator between coordinate systems comes up pretty often. While there are tables for converting between common coordinate systems, there seem to be fewer explanations of the procedure for deriving the conversion, so here goes!

What do we actually want?

To convert the Cartesian nabla

to the nabla for another coordinate system, say… cylindrical coordinates.

What we’ll need:

1. The Cartesian Nabla:

2. A set of equations relating the Cartesian coordinates to cylindrical coordinates:

3. A set of equations relating the Cartesian basis vectors to the basis vectors of the new coordinate system:

How to do it:

Use the chain rule for differentiation to convert the derivatives with respect to the Cartesian variables to derivatives with respect to the cylindrical variables.

The chain rule can be used to convert a differential operator in terms of one variable into a series of differential operators in terms of othe…

### Lost Phone

We were incredibly lucky to have both been in university settings when our kids were born.  When No. 1 arrived, we were both still grad students.  Not long after No. 2 arrived, (about 10 days to be exact), mom-person defended her dissertation and gained the appellation prependage Dr.

While there are lots of perks attendant to grad school, not the least of them phenomenal health insurance, that’s not the one that’s come to mind for me just now.  The one I’m most grateful for at the moment with respect to our kids was the opportunities for sheer independence.  Most days, we’d meet for lunch on the quad of whatever university we were hanging out at at the time, (physics research requires a bit of travel), to eat lunch.  During those lunches, the kids could crawl, toddle, or jog off into the distance.  There were no roads, and therefore no cars.  And, I realize now with a certain wistful bliss I had no knowledge of at the time, there were also very few people at hand that new what a baby…

### Lab Book 2014_07_10 More NaI Characterization

Summary: Much more plunking around with the NaI detector and sources today.  A Pb shield was built to eliminate cosmic ray muons as well as potassium 40 radiation from the concreted building.  The spectra are much cleaner, but still don't have the count rates or distinctive peaks that are expected.
New to the experiment?  Scroll to the bottom to see background and get caught up.
Lab Book Threshold for the QVT is currently set at -1.49 volts.  Remember to divide this by 100 to get the actual threshold voltage. A new spectrum recording the lines of all three sources, Cs 137, Co 60, and Sr 90, was started at approximately 10:55. Took data for about an hour.
Started the Cs 137 only spectrum at about 11:55 AM

Here’s the no-source background from yesterday
In comparison, here’s the 3 source spectrum from this morning.

The three source spectrum shows peak structure not exhibited by the background alone. I forgot to take scope pictures of the Cs137 run. I do however, have the printout, and…