Friday, May 13, 2011

Catching Up

Sheesh, it's been more than a month since my last real post. We've been busy.

As always, click on the small photos to go to a photo album for each story.


New York Weekend


At the beginning of April we went to New York for a weekend to visit my friend Brady and his daughter Isabel and attend Sleep No More.

We had a great weekend. Saturday we all went to the Metropolitan Museum. We weren't sure if the girls would enjoy it, but we promised them they'd see suits of armor. On the way to the armor we passed through the Egyptian section (including the temple) and the Art Deco section. They liked all of it. After the museum we went across the street to the Ancient Playground where the girls had a blast.

Saturday night we spent at the performance, which was fascinating. Our friends had seen it in Boston last year when it was staged in an empty school and had raved about it. It lived up to the hype. Just the "set" was amazing: five floors of multiple adjoining warehouses, all meticulously constructed and decorated and available for audience exploration. And the performance was intriguing, too. It consists of about eight or nine non-speaking characters moving through the space and periodically interacting. Audience members just follow whichever character they want, or none at all. We're very glad we went.

On Sunday morning we went to Cafe Centosette, which was Brady and Isabel's favorite breakfast spot. Unfortunately we found out during our meal that it was their last day in business. The rent was raised and was now too high. Bummer. But Brady asked the secret of their delicious Dutch Babies: it's Bisquick! And a cast iron skillet.

Crane Estate May Day Open House


We subscribe to a weekly email list called Boston Central that lists stuff to do with kids. It's been a fantastic resource and probably once a month we do one of the activities we learn about from that source. The most recent was the Crane Estate Open House on May Day. The Crane Estate was the summer home of plumbing fixture magnate Richard Crane. It is now owned by the Trustees of Reservations, a New England open space and heritage site preservation group. Another part of the property is Crane Beach which is very popular in the summer.

Carol packed a picnic for us and off we went. There were a few hundred people there but the grounds are huge so it didn't feel crowded. We played croquet and chased each other around and had a delicious lunch. The Castle Hill mansion was open for self-guided tours. Then local high school girls danced around a may pole. We wandered down the Grand Allee to Steep Hill Beach and played on the beach for a good long time. I drew a maze in the sand. It was the first time I've ever drawn a maze; it turned out to be not too difficult to solve. Of course being in only two dimensions didn't help since you could see right over the "walls".

Mystic Seaport


We visited Mystic Seaport last April and had such a great time we've sort of decided to make it our annual first camping trip of the year. So the first weekend in May we drove down after the girls' ballet lessons on Saturday and arrived mid-afternoon.

The girls were excited to go straight to the playground, which consists of three boat play structures that kids can climb in and on: a tugboat, a fishing boat and a sailboat. They could play there for a very long time. Right next door is the "Children's Museum" which is the ground floor of a converted house that contains: another fishing boat structure with fish they can catch and decks to swab and woodwork to paint; a couple of sailor's berths; and a galley in which they can pretend to cook up a feast.

This year there's a new indoor area in one of the real museum buildings that has a puppet theater, period dress-up clothes (Mystic Seaport mainly focuses on the mid-19th century when Mystic was a thriving shipbuilding center), and some cool old games and puzzles. So we spent a lot of time there as well.

We only had a couple of hours on Saturday before closing, but tickets are good for a second day. So we headed to the local KOA campground and made dinner. While we were eating a thunderstorm approached from the southeast. We quickly cleaned up and got in the van as it started to rain a little. We were hoping it would roll right over us because that would have been cool in the van, but it just brushed us with a little wind and rain. We could see plenty of lightning nearby though and hear thunder.

Sunday was Mother's Day. I had researched local breakfast places and decided on Kitchen Little. It's very near Mystic Seaport so we had passed it on Saturday. It's definitely little. Although once inside we found it packs people in very efficiently and can actually hold probably 40 people, partially in a covered outdoor area overlooking the river.

Back at Mystic Seaport we revisited the huge scale model of the Mystic River that does a great job of showing what the area was like in the 1850s, including the many shipyards and ships in various stages of construction. We also spent a fair bit of time aboard the Charles W. Morgan, the last surviving wooden whaling ship which is being painstakingly restored. The restoration is an amazing process with a fascinating facility. They rebuild parts of the ship using the same materials and techniques as were originally used.

Finally, the most popular activity with kids is a little shop where they can build their own boats. There are small pieces of wood in various shapes plus paper, string and hot glue guns that they can use to build whatever they want on top of a bare hull. They love it.

We had just as much fun as last year, so our plan of making it an annual event is confirmed.

Oh, the campground also has a big jumping pillow that we all love.

Everything Else


Boy, there is lot of other spring news, too.

Charlotte is wrapping up Pre-K and will go to full-day Kindergarten next year at the same school Audrey attends. We're very excited for everyone to be able to walk to and from school together. Audrey is wrapping up first grade and has had a great year. She's becoming quite the reader, which warms my heart to no end. She has recently taken up the habit of spontaneously curling up with a book.

Audrey has also started losing her baby teeth. On the bottom the new teeth came in behind the old ones and in January the dentist pulled the two front bottom baby teeth (with some kind of magic: Audrey liked the experience!). The top two front teeth were loose seemingly forever but finally came out a couple of weeks ago. She looks damn cute with her gap-toothed smile.

Both girls have been excited about riding their bikes this spring. Audrey shed her training wheels last summer and she picked up right where she left off. Charlotte has decided to ride with training wheels after not liking them last year. On nice days they both ride their bikes to Audrey's school with mom walking along.

Carol took the girls to the deCordova Sculpture Park and Museum one afternoon and they enjoyed all the outdoor sculpture as well as the indoor exhibits.

We also attended the MIT Open House on April 30. It was the first campus-wide open house in 30 years. A fellow robot team mentor works at the Plasma Science and Fusion Center and had specifically told me about events there, so we made sure to attend the Plasma and Pickles presentation. We also saw some robot demonstrations and Audrey got to fly a quadracopter. I got to see a lot more of the MIT campus, which I ride my bike past every day on my way to and from work.

Finally: several years ago I read an article about the invention of colored bubbles. It's a very difficult problem because:
  1. soap bubbles are very thin and dye is heavy enough that it just flows to the bottom of the bubble
  2. it was hard to come up with a dye that wouldn't stain kids' clothes
But after more than a decade of work an inventor figured it out.

After reading the story I was excited for the bubbles to hit the market so I could try them out. But that never happened. Then a week or two ago we saw an ad on TV for Crayola Washable Colored Bubbles. I'm not sure if it is the same chemistry as that described in the article, but they are the first colored bubbles I have seen on the market. Carol picked up a the pink and green varieties for the girls (and for me).

Unfortunately, they are a bit of a disappointment. The green ones have a fair bit of color to them but the pink ones are very faintly colored. However, even though they are "washable" the fluid is very dark colored (the pink looks like slightly watered down blood) and it's very hard to believe that they aren't going to stain anything they touch. We did prove that it washes right off of concrete and that it can be easily blotted out of cotton clothing.

It was interesting to close the loop on the story. I'm not sure if we'll be buying any more of them.

Whew, we're all caught up now.

Sunday, April 17, 2011

New Old Videos

I recently received notice that Google Video is moving from dormancy to complete shutdown, so I had to rescue some old videos and move them to my current video host: Vimeo. I thought methot.net readers might like to take a little trip down memory lane.


Belltown Crane Erection: in 1999 a new apartment building was built right outside my apartment window in Seattle's Belltown. I happened to be home the day they erected the tower crane and I made a time-lapse movie of the 14-hour process.


My Mother the Car: A video from April 2008 in our Seattle kitchen


The Bed Cave: A video from April 2008 of the girls playing in our Seattle house


New Swing Set: from June 2008. While the girls were visiting grandparents I assembled the new swing set. When they got out of the car from the trip home they jumped right on.


Thomas Stop-motion: a stop-motion animation experiment from March 2008.


Scared Bot: a robot I built with LEGO Mindstorms in June 2008. It is afraid of everything.

Thursday, April 7, 2011

Fairies and Birds

On March 20 we visited the Wenham Museum for a workshop run by fabric artist Elizabeth Golz Rush. She provided kits she had prepared and the girls (about a dozen were in attendance) assembled the dolls and then decorated them as they wished. Audrey and Charlotte loved it.

Neither Carol or I felt like fighting the hair-brushing battle on the way out the door, but then we were a little embarrassed to have girls with rats' nest heads. Especially with one of the museum volunteers taking photos. Oh well. Live and learn.

After the workshop we wandered around the museum. There was a wonderful temporary exhibit of miniature houses. And a very cool permanent exhibit of dolls, doll houses and doll clothing. There was also a very small photography exhibit that included two film cameras that kids could handle. I tried explaining the concept of "film" to the girls but I don't think it really sunk in.

By then we were hungry and headed to the town of Hamilton very nearby for some lunch. In the Boston area there is a particular kind of casual food joint. They all have the same menu (pizza, subs, gyros, maybe spaghetti) and in fact they all have the exact same physical menu (example). The Hamilton House of Pizza was typical. And good.

The towns of Wenham and Hamilton border the south edge of the Ipswich River Audubon Sanctuary (which by now you know has become our favorite place) so we headed there next. We had finally bought our own bird seed after relying on the generosity of others on previous visits so we were excited to try it out.

Upon our arrival, though, we first of course had to visit the Rockery - the 50' tall pile of washing-machine-size boulders that were arranged 100 years ago into an artificial mountain with stairs and paths and a grotto. Unfortunately, the paths were all still covered with compacted snow and ice (the Rockery is very shaded) and it was treacherous. So we went off on a hike instead.

We often go geocaching for fun. I had discovered that there was a fairly new cache in the sanctuary so we set off toward that. Along the way we found a spot near the Old Stone Bridge where the birds were especially hungry. We fed them for a long time. Then I finally coaxed the girls to continue on to the cache. We had to travel down a trail that was new to us, along an esker. There was a cold wind blowing off the marsh, so we hurried along. We found the cache, and we also found a very friendly nuthatch so Audrey spent some time feeding him (they are much more shy than the chickadees). Then we found another new trail that was a shortcut back to the car. A very fun day.

Charlotte & Dad One-on-One Day

Back in mid-March Audrey and Carol had a plan to go skiing with a friend for his birthday. He ended up canceling because he was sick, but Carol and Audrey went anyway. So Charlotte and I had a one-on-one day.

We started by going ice skating at the local public rink. Charlotte was nervous at first and used a milk crate, but after about half an hour she put the crate away and skated all on her own. She was even doing some turns in place! It took me a while to get my skating legs back but it came to me. It was also my first time on hockey skates and I decided I like them better than figure skates.

After skating for more than an hour we went and refueled with donuts. Charlotte got pink sprinkles, of course.

Then we drove to the T and rode it into town to visit the Children's Museum. I had never been and Charlotte had only been once. We had two hours until closing and it went by very quickly. There is a huge climbing structure in the main entrance area. Charlotte was tentative at first and would only climb up to about 6 feet off the floor. But I pointed out that she couldn't really fall anywhere and she started pushing her boundaries. Before you know it, she was climbing all the way to the top - three stories off the floor. After that she couldn't get enough and she went all the way down and back up three more times.

That used up at least half of our time before closing, so I coaxed Charlotte out of the tower and we explored a few other areas. She got to light up some lights by pedaling a bike and she got to ride in a vertical rail chair that I could raise and lower with a rope and pulleys. The we chased each other around a boat playground area.

We definitely didn't get enough time there and have to return. I finally broke down and bought a membership so we'll go there often.

The girls hardly ever get solo time with a parent. Carol and I decided we'll make it a regular occurrence: every couple of months we'll swap kids and take them off by ourselves on an adventure.

By the way, Carol and Audrey had a great time skiing but Carol was having so much fun she didn't take many photos.

Friday, April 1, 2011

What the heck are all those different units of radiation?

If you've been reading very much press about the ongoing nuclear disaster in Japan, then you have likely been confused by the wide variety of units in which radiation measurements are reported. I was. Yesterday I spent some time reading various Wikipedia articles (see links in text below) and organized the information into a guide that I hope is useful for someone with moderate scientific knowledge.


There are three aspects of radiation that are measured by various units: what is happening in the radioactive material; what exposure does a nearby object experience; and if that object is a living organism what biological effects does that exposure produce.

The material is undergoing radioactive decay. Unstable isotopes are decaying and emitting alpha particles, beta particles and gamma rays (there are other forms of ionizing radiation but these are the ones of concern with regard to nuclear fuels and their by-products).

The most basic measurement is the total number of disintegrations occurring per unit time in the material:

becquerel (SI unit) = 1 disintegration/second
curie (traditional unit) = 37 billion disintegrations/second

The emissions are in all directions. At a detector the most basic measurement is Counts Per Minute (CPM): the total number of disintegrations (alpha particles, beta particles and gamma rays) arriving at the detector. Keep in mind that the detector does not typically completely surround the source, so CPM is only the emissions  that reach the detector.

Emissions encountering an object accumulate in that object and add up to "exposure". Exposure units have a complicated history and taxonomy.

roentgen (traditional unit) is "the amount of radiation required to liberate positive and negative charges of one electrostatic unit of charge (esu) in 1 cm³ of dry air at standard temperature and pressure (STP). This corresponds to the generation of approximately 2.08×109 ion pairs." Use of roentgen units is now discouraged.

rad (traditional unit) is "the dose causing 0.01 joule of energy to be absorbed per kilogram of matter"

1 roentgen = 1 rad, approximately.

gray (SI unit) is "the absorption of 1 joule of radiation energy per kilogram of absorbing material". 1 Gy is approximately equal to 115 roentgens.

The effect of the radiation exposure on the object depends on the composition of the radiation (the proportion of alpha, beta and gamma radiation) and the object's material. So subsequent units use a conversion factor ("quality factor", Q) that reflects the biological effects on humans. Q ranges from 1 for x-rays, gamma rays and beta particles to 10 for neutrons to 20 for alpha particles.

rem ("roentgen equivalent in man", traditional unit) is a measure of "radiation dose equivalent" and is the product of the quality factor times rads (or roentgens).

rems = Q x rads

The SI unit of radiation dose equivalent is the sievert. 1 sievert (SI unit) = 100 rems.

But that's just a measurement of energy absorbed adjusted for biological effect on human tissue without regard to duration of exposure. One could absorb a given amount of energy in a minute or in a lifetime. The Wikipedia sievert article lists doses for single events like dental x-rays as well as dose/time examples such as average background radiation exposure for an American resident per year.

In most countries the current maximum permissible dose to radiation workers is 20 mSv per year averaged over five years, with a maximum of 50 mSv in any one year. This is over and above background exposure, and excludes medical exposure.

The sievert article also gives symptom benchmarks:

Symptoms of acute radiation (dose received within one day):[20]