Friday, August 31, 2012

The myth of the 100-year flood

Casual handling of statistics make me cranky.  So we take a break from job-seeking and a SQL tutorial for this public service announcement about the so-called 100-year flood.

WaPost's Five myths about Hurricane Katrina included this tidbit:
4. New Orleans’s levees are fixed and could withstand another Katrina.
After Katrina, Washington committed $14.5 billion to flood-protection improvements that are supposed to survive a 100-year storm — a term of art that refers to storms that have a 1 percent chance of striking in any given year.
Kudos to writer Jed Horne for using "term of art" to emphasize that the term has a specific actuarial and regulatory definition.

Unfortunately, most people are not so careful.

If an area has a 1% chance of flooding each year, it does NOT mean that it will flood once per century.

I fired up python in an OS X terminal, but you can use any calculator or programming language you like to replicate these results.

Assuming each year is independent of every other year, you have a 99% chance of NOT being flooded in any given year.  Over a 100 years,

>>> .99**100
you have a 36.6% chance of escaping flooding.
You also have a 1 - 0.3660323412732292 = 63.4% chance of being flooded at least once per century.

Over 50 years,
>>> .99**50
you have a 60.5% chance of escaping flooding.
Conversely, you have a 1 - 0.60500606713753635 = 39.5% chance of being flooded at least once.

Suppose you have a 2% chance of flooding each year.  Over 100 years, 
>>> .98**100
you have only a 13.3% chance of escaping flooding.

Hey, that doesn't scale (linearly)!  ;-)

The power of powers never ceases to amaze.

You may also want to read What planet are they on? for another illustration of nonlinear phenomena.

Tuesday, August 28, 2012


How do you use your collections?  First In-First Out?  Last In-First Out?

Sometimes, I sew the latest fabric purchase on top of the stack.  Other times, I rummage through the bins for a specific color and unearth pieces purchased long ago.  This project is LIFO because it was sewn up within a week of arrival.

I purchased this costly Liberty of London Tana Lawn during my last visit to Elfriede's Fine Fabrics in August.  (BTW, though the fabric is costly by my standards, it was only $40/yd at Elfriede's for the 54" Tana Lawn vs. $50/yd I've seen elsewhere for the exact same thing.)

I purchased 3/4 of a yard, or $30 worth because it perfectly matched a cardigan I was knitting at the time, I love the feel of Tana Lawn, and the shell in Vogue 1071 uses the fabric very efficiently. 

The last time I made this blouse, it rode up slightly at the hips.  For this version, I added about 1.5" around the hips and it fits much more smoothly.  Of course, I only have photos of it worn tucked in so you can't see that. ;-)

You can see the nice buttons that I recycled from an old and (sadly) shrunken linen blouse (another Calvin Klein pattern).  The front is lined with red/white cotton batiste rescued from the SBQG share table.  I like this blouse so much, I pulled out a cotton lawn remnant purchased from Poppy Fabrics about 25 years ago to make another!  If that is one of the oldest fabrics in my collection, does that make it FIFO?

It's a high-low outfit because I purchased the skirt fabric from barrels at Trash For Teaching for $1/pound. The fabric is factory waste from American Apparel; their factory is only a few miles from T4T.
At T4T we strive to source wonderful, clean, safe, interesting items that local businesses discard in abundance, and make them available to shoppers at the warehouse. Over the past 8 years we’ve collected materials from over 200 companies, most of those original manufacturers still donate to T4T today. Since we first opened our doors in 2004, T4T has diverted over 50,000 pounds of materials from local landfill. Those materials include an abundance of plastic and cardboard thread cones, in all colors shapes and sizes, beautiful wood from a shutter company, plastic color chips, glass tubes, fabric and trim, colorful rubber mats, tiles, tubes, Styrofoam….and the list goes on.
BTW, if you are visiting LA and have a rental car, it's worth visiting T4T and exploring their warehouse neighborhood (near the intersection of I-110 and I-105) to learn just how much (besides celluloid) the region manufactures.  T4T also sells science "teacher kits" made up of trash with lesson plans at bargain basement prices.  The kit for teaching optics is genius!  I say that in earnest.

Anyway, the linen was celadon green and the jersey was light olive green.  I dyed the linen to match the jersey and then lined it with gray rayon lining, which deepens the green of the linen.  Notice also that the hip yoke has darts incorporated into the seams.   The linen is cut on the bias.  I drafted the pattern.  I made a bias top to go with it.  The set deserves it's own post at a later time.

Monday, August 27, 2012


I succumbed to impulse purchases at Elfriede's Fine Fabrics this summer.  This 1/2 yard piece of 54" wide silk shot chiffon (fuchsia in one direction, black in the other) was only $4 so it came home with me.  It would have made a rather short scarf on it's own.

But, then I saw Habu N-80, a silk-wrapped merino yarn, at Twist during their summer sale.  I bought a 1 oz skein (187 yds), cast on 40 sts and knit in elongated seed stitch on size 7 (4.5 mm) needles until I ran out of yarn.

I sewed the chiffon into a tube in the long direction and inserted the knit piece in between the short ends to form a tube about 80" in circumference and 9" wide.  It can be worn looped three times (above) or twice (below).

I just love the textural contrast between the smooth chiffon and the seed stitched wool.  The wool is surprisingly not scratchy after I washed and blocked it (before sewing it to the chiffon).

Does your stash grow while you sleep?  I do not understand how this ~2 yard piece of silk came to be in my luggage.  When I unpacked my purchases from the trip, there it was.  Where did it come from?

@ Shams: The silk was folded up in a 1 quart ziploc bag, which stores don't usually use.  It's extremely odd.  I don't think that Stone Mountain and Daughter gifted this to me--though, in the 1980s, they used to gift me quite a bit of fabric with their generous cuts.  I actually thought that I was able to buy 1/4-1/3 less fabric all the time because I was so efficient with layout.  Another seamster insisted that I measure my fabric and she was right.  Remember the rule about "a yard and a thumb"?  Well, the cutters at SM&D had very fat thumbs for their regular customers.  I shopped there both for my personal needs and for the costume shops of Berkeley Shakespeare and Repertory so the cutters knew me.

Thursday, August 23, 2012

Staged Fight

They aren't really fighting. It only looks that way because I saw the two carcasses lying in the sand close to one another and thought they looked like two creatures from a B horror movie.  So I staged a mock fight between them.

BTW, the picture above was taken at Limantour Beach, part of Point Reyes National Seashore.  From the beach, I also saw puffins fishing offshore.  I had to use binoculars to see that the black birds were, indeed, puffins with bright blue heads and yellow beaks.

We spent a lovely two days at a friend's cabin.  Here's the view from the deck where we sat reading side by side.

We crossed CA Hwy 1, the Pacific Coast Highway, on our way between the cabin and Pt Reyes.  I mentioned that it's possible to follow PCH all the way home.  The cabin and our house are both about a mile east of PCH, but hundreds of miles of coastline apart.

On our way up to the cabin, we were able to stop and meet Shams for lunch.  While I was in the restroom, TFN* confessed to Shams that she was nervous about spending two days in a small cabin alone with me without wi-fi.

I am happy to report that we got along very well.  If she wanted to eat chocolate cake for dinner, I let her.  I wasn't going to let an argument ruin my relaxation.  I suspect (hope?) she played up the tension for comic effect.  Or to manipulate me into letting her eat junk food.  Whatever.

BTW, on the beach, she showed me how to stage fight.  Only she said I did it wrong.

* Shams renamed her TFN.  We are not sure what that means but, some days, the Urban Dictionary's TFN definition #2 rings true.

Wednesday, August 22, 2012

Bribing teachers, yeah or nay?

Today's blurb from the good people* at Proctor and Gamble via their Home Made Simple website and email.
Get the school year off to a good start and surprise teachers with one of our 16 simple handmade gift ideas.
Honestly, I never thought of giving anything at the start of the school year with the exception of one or two items from the teacher's wishlist sent home with the student early in the school year.  The district is chronically short on funds and I don't think teachers should shoulder the cost of equipping a classroom.  We buy Costco-sized quantities of some of the items on the list so it is no problem to send a subset of it to school with my child.

But personal gifts at the .beginning. of the school year just seem too blatant for my taste.

I really do want to know what you think.  I am especially interested in customs and social norms outside of the United States.  So what do you think?
  • Is it appropriate to give a gift at the start of school? 
  • Or would you wait until the  end of school** (as I do)?  
  • Or skip it altogether? 
  • Or would you stick to the teacher's published "wishlist" of office & classroom supplies? 
* I don't mean that facetiously. I think that P&G is one of the better companies out there. At least, they publish their ingredient lists--though you have to do some digging around in their website to find them. Did you know that, since the 1980s, manufacturers of household chemicals are .not. required to tell you what is in your formulations? If your household cleaners contained toxins, carcinogens (cancer-causing chemicals) or endocrine disruptors (synthetic hormone-like chemicals), wouldn't you want to know?

** I've blogged about making teachers' gifts many times previously.  Most recently, I transformed some boxy math meet t-shirts into a more fitted and feminine style for several of the math teachers who volunteered their time to mentor the team.  When the Pattern Magic book came out in English, I purchased them again and gave the Japanese language edition to the teacher that teaches both Geometry  .and. Japanese.

Monday, August 20, 2012

Museum Gems

Our family went to see the completely uninspired ... Is James Bond exhibit at LACMA (Los Angeles County Museum of Art).  Do you really need to devote a gallery to screens showing the James Bond opening sequences without curation?  One can learn more by staying at home to view them and read the DVD inserts.

However, if you really want to learn about the gems on view, ask the security guards for their favorite shows.  I asked one lady at the top of the stairs in the Ahmanson building what I should see if I was particularly interested in textiles.  She didn't skip a beat before enthusiastically recommending that I see the molas in the back back corner of the Art of the Americas section.

Wow.  I've never seen molas like this before.  Even though the exhibit is confined to one small gallery in the back corner, it packs quite a punch.  Molas are small, so there are many of them on view.  Additionally, many of them were loaned by a collector with exceptional taste and access to some of the finest mola art I have seen anywhere.

Most of the molas you see for sale and bought by travelers are necessarily quickly made to keep the prices low enough to easily sell.  You don't see such detailed (and expensive) molas very often.  All of the pieces were exceptional in craftsmanship and the curation is first-rate.  The show gives a broad view of the history, meaning and purpose of molas--from the spiritual to the political to the economic--and it includes a broad cross-section of the themes found in molas.

The show closes on October 13, 2012 so visit it soon.  The lighting is dim and I don't think that photography is allowed, so bring your notebook to take down notes and ideas.  This is a show I need to go back and revisit.  It's that good.

Stitching Worlds: Mola Art of the Kuna

The next time I go, I want to check out the newly-opened Ohie Toshio and the Perfection of the Japanese Book, in the Japanese pavilion.  Check out the beauty of that inlaid leather and the asymmetric, yet pleasingly balanced composition. It's on view through October 21, 2012.
Anyone want to make a museum and lunch date? Little Ethiopia with it's plethora of dining options is very close to LACMA.  Museum admission is always free for children 17 and under.  Each child can bring in one adult companion for free.

Wednesday, August 15, 2012

Some nerds go on a hike

along the mesa trail after being kicked out of the computer lab at NCAR's Mesa Lab (aka the Sleeper building).
Unlike the previous days, there were no afternoon thunderstorms and the mid-afternoon heat and altitude were challenging.

Nerd 1: (Looks at watch.  4:45 PM)  What do you think?  600 watts per square meter?

Nerd 2: (Looks at sky.)  Given the altitude, perhaps 650.

Nerd 2 works at the Department of Energy's Atmospheric Radiation Measurement (ARM) Program Southern Great Plains (SGP) Central Facility, Oklahoma so she looks at solar irradiance data for a living. Nerd 1 has no excuse other than being a nerd.

A quick search yielded a compendium of solar irradiance data servers put together by NREL.  Following the link to National Wind Technology Center, enter in the day of the hike and voila.  Click to make the graph below bigger and you will note that, taking into effect daylight savings time and averaging over the noise of passing clouds, Nerd 2 was spot on!

Check out the solar irradiance back at the beach on an exceptionally sunny and cloud-free day.

BTW, solar irradiance is a measure of the amount of light energy per unit area from the sun, integrated over all light frequencies.  See the solar spectrum and images of the sun at different frequencies, including the UV and X-rays.  Fortunately, the ozone layer screens out much of the UV so we don't fry here on the surface.

If you want to see how much power you can generate with photovoltaic cells on your house, take a look at the climatology of solar irradiance near you and multiply by the efficiency factor for the type of panel (a number much less than 1 or 100% efficiency).  Does the sun generally shine when you need to draw power?

The reliability and availability of solar power deserves it's own post.  Later.

Monday, August 13, 2012

Two nerds drive up a mountain pass...

The minivan gives the outside temperature.
The GPS unit gives the altitude.

She: Our lapse rate is slower than the saturated adiabatic lapse rate.

He: That's because we are driving into a storm front.

She: Isn't that what I just said?

Bystander in the backseat: Huh?

Background: If a parcel of dry air is lifted adiabatically (without exchanging heat with its surroundings), then the temperature cools off 9.8 degrees Celsius per 1000 meters altitude.  If the air is saturated, it cools off more slowly,  about 5 degrees C per 1000 meters.

Traveling between Durango and Silverton, along the Million Dollar Highway, our elevation went up by over 3000 feet or about a 1000 meters, but the temperature only changed about 3 degrees C.

That very low lapse rate implied that we had crossed the boundary between two distinct air parcels--what is commonly called a front.  It might have also implied that we got caught in the upslope of a diurnal mountain-valley circulation, but it was the opposite of the type of calm and sunny day that sets up that type of wind pattern.  It was cloudy and cold.  When two air masses collide, a violent storm can erupt.

Sure enough, it started to rain as we crested the pass, gradually becoming heavier and there were even a small amount of hail.  What a great day for a picnic!  ;-)

On that day, it did NOT look like this picture from Wikipedia commons, but it was beautiful nonetheless.

Thursday, August 09, 2012

No more bubbles! (of the bad kind)

There was an internet rant about sewing tutorials written by hipsters who learned how to sew 10 minutes ago that promulgate very bad techniques.  I stayed out of the fray, but nodded my head in agreement.  Some of those blogs give information that is just flat out wrong.  The best sewing advice I have seen have usually come from women who have sewn for decades and are not as photogenic and thin as the hipsters with their beautifully-styled blogs. 

One of the best sewing tutorials sites is run by Pam Erny, proprietress of Fashion Sewing Supply.  Her recent tutorial on how to make two exactly identical shirt pockets was fantastic.  I emailed her right away to ask if there was a way for me to send a micropayment to her for the sewing lesson.  She said that was not necessary, but she would appreciate if I spread the word about her business.

If you read sewing blogs of experienced seamsters, you may notice that many most of us purchase interfacing and notions from FSS.  To save on shipping, I put in an order every year or so, whenever I run low.

Actually, I don't recommend .ever. using fusible interfacing from big box sewing/craft stores.   The Pellon stuff will bubble eventually, ruining all of your hard work.  The Handler Textiles interfacing from independent fabric stores is slightly better, though it's a drag to wash and rewash the stuff to shrink it before application.

But, if you really want your work to hold up, wash after wash, and you don't want the hassle of prewashing your interfacing, you need to use the stuff Pam sells at FSS.  It's preshrunk, before the adhesive is sprayed on the back.  That means, the interfacing won't shrink when you iron it on your fashion fabric, causing the dreaded bubbling.  Moreover, the adhesive is applied evenly and thinly; no dots of adhesive that show through here.

I have no affiliation with FSS except that I am a satisfied customer and I am not paid for this plug.  But, I would like to point out that Pam is having a huge sale right now to celebrate her 7th year in business.

The sale runs through August 15 so take stock of what you need soon and place your order. She often runs out of some type of interfacing I want during her sales. But, last time, she held off shipping my order until she was able to restock, so I only had to pay for shipping for one package. Her shipping rates are reasonable; she charges only what it actually costs her (unlike other places!).

Monday, August 06, 2012

Congrats and oops

My daughter and I watched this NASA video of the Mars rover landing last night.  The tension and the joy among the team were palpable.  Congrats!

We had to go back and watch this conceptual animation of the landing sequence so that she could follow along with the audio commentary calling out key milestones in the landing sequence.  It is truly worthy of Rube Goldberg.

It's pretty neat to think about how the robot I watched being assembled back in 2010 in the JPL clean room in Space Day is now on Mars.  Go see the photos in the post!

The dark cloud is how many of the JPL team will be laid off.

Tangential oops

I read some internet chattering about how Scripps Local News, a for profit company, had blocked NASA from showing the top video on Youtube.  Motherboard gives an excellent summary and analysis of the problem of fraudulent claims of ownership  on Youtube.  I was surprised that this also happened in April and that the process/software had not been changed to prevent this sort of thing from repeating.

And that, the miscreant, Scripps, is .still. able to claim ownership of NASA videos after they were caught last time.  It's a wonder that they are able to claim ownership of .any. videos after their repeated abuses of posting other people's content and claiming ownership.

Youtube has a massive problem of policing pirated content on their platform.  Remember the days of uploading your content to Google Video and waiting hours for a human to view and approve the content?  Youtube automates the review process and the turnaround time for videos to go live has gone down to just minutes.  However, robots are only as good as their algorithms and they make mistakes.

Here's a laymen's description of the system.  Data and software geeks may want to go to the source and read an IEEE paper written by Google engineers, Video2Text: Learning to Annotate Video Content.  Robots, metadata and supervised learning, oh, my!  While reading about their training methods and how they calculate correlation functions for video content with multiple time offsets, can you feel the heat coming off their servers?  That's a seriously hot process!

It ties in nicely to the Learning from Data course from Caltech.  Speaking of which, I should get back to the homework set for the class due tomorrow.  The Stanford/Coursera online AI class is a stroll in the park compared to the Caltech class, but I'm learning much more from the latter.

For more background, read Fight Back Against Content Theft.  Google search algorithms give a weighting to content "freshness" and "originality".  Scripps' robot software beat out NASA to appear as if they were the originator of the content.

Inside Search, the official Google Search Blog, recently wrote about some search tweaks. If you were a web crawler, you'd know how much badly-written dreck there is out there on the internets. They program their web crawler robots to search for original content that can't be found elsewhere. I put significant effort into What Do Automobiles and Spacecraft Have in Common? and it's not a connection that I've seen pointed out in the popular press. Unfortunately, the first time the web search robots encountered it was on a spam blog. Don't let that happen to you.

Sunday, August 05, 2012

Unsportsmanlike or defensible strategy?

When Bad Dad picked me up at the airport last night, he asked my opinion about the olympic badminton scandal. I had to confess to being too busy at the NCAR class and visiting with Boulder friends to follow the olympics.

When he explained it to me, I could see the everyone's point.
  • It wasn't fair to the fans that paid about $50 a ticket to see the thrown matches.
  • It wasn't fair to the players because throwing a match in order to get an easier match in the next round is not against the rules.  Who wouldn't want to preserve their energy for the single elimination round if you are already qualified to advance?  And why wouldn't you aim for the easier draw if you could?
  • At this high level of sport, the coach makes the call.  The Chinese coach has already apologized for ordering his players to throw the match.  
  • If the players had disobeyed their coach, how long do you think they will remain on the Chinese national team?
  • It was the fault of the officials for not anticipating this entirely rational response by the players and their coaches.
NBC paid a billion dollars for the right to broadcast the olympics.  The WSJ paid considerably less than that.  I laughed out loud when I saw this WTF video produced by WSJDigital.  Despite the clothespin players, this is a very good explanation of the events.  Besides, badminton is the fastest of all racket sports, exceeding 200 mi/hr initial speed at this level of competition.  You are unlikely to be able to follow along in a normal speed video.  The pom pom here is more illustrative.

In case you were wondering why Bad Dad wanted my opinion

I played on my high school badminton team. I made junior varsity as a freshman and varsity in my sophomore year as part of a doubles team. I played varsity singles my last two years of high school and was the top seed for my school in my senior year.

For the last two years, our HS coach was a former NFL football player and track and field star in college.  I have never spent that much time with such a gifted athlete before and it was a revelation.  Part of the revelation was how much preparation and thought he put into being a "gifted" athlete.

No coach before or since has ever kept such good statistics of my game stats and analyzed so minutely why I won or lost certain matches.  It's quite painful and enlightening to have your strengths and weaknesses catalogued like that.  It was excellent preparation for grad school.

And then there were my club volleyball years

Average-height girls (5'5") don't usually get much game time at the competitive club volleyball level but I developed some skills to compensate.  One VB coach used to put a towel on the court and watched as we took turns to serve a ball to the towel.  We'd have to run a (1/4 mi) lap after practice for every ball hit into the net or that went wide.  I became very accurate.

Statistically, it's a good practice to serve at the player closest to the setter in the rotation.  You can either draw and force the setter to take the serve return, or slow down the transition to the set by causing interference between that player and the setter.  Either gives the serving team an advantage.

In one game, the setter was in the middle, which meant that there was enough margin of error for me to serve "floaters", which can jump suddenly and unpredictably in the last split second.  I did what came naturally and the non-setting player muffed several passes.

Her coach called a time out to let her calm down.  My coach told me to keep serving to her.

We scored more points.  They called another time out.

Then her teammates crowded around her to give her protection, leaving the corners of the court open.  I served an ace into one of the corners and the players edged back into their normal positions.  I returned to serving the girl who was crying.

I served 15 balls in a row to wherever my coach signaled me to place them.  At the end of that match, I was emotionally worn out and crying, too.  I wasn't proud of myself for inflicting emotional damage to an opponent.  But, that was my coach's call and a winning strategy.

How can I fault another player for doing the same?

My heart goes out to the disqualified badminton players.

Wednesday, August 01, 2012

Back in Boulder

Having a challenging (but fun!) time learning how to run the CESM climate model on a supercomputer.    I figure, as long as I need to brush up on my high performance computing skills to enhance my employability (the unemployment counselor's terminology), then I might as well pick a use case that is intellectually interesting to me.  ;-)

This photo was taken after quite the afternoon thunderstorm.

You can see the back of this refashioned dress in Shirtdress shortcut.