Friday, September 28, 2012

Shirt Woot's "Propaganda...FOR SCIENCE!" contest

Speaking of blue lasers, my friend was like: "check out this shirt."
And I was just like: "OMG I need it."

Fuck yeah, it's a dinosaur shooting a blue laser out of his mouth with a nuclear explosion in the background!

From the Shirt Woot shop:
...Science isn't all dinosaurs and laserbeams. Being a scientist takes hard work, attention to detail, and making imaginary women come to life with your computers... Science is serious business. Just ask any professional scientist who has ever turned a sports car into a time machine, stolen plutonian from a group of Libyan terrorists, and sent your teenage friend back to 1995 just as you are shot by the terrorists. It's a job just like any other.

This design was the winning finalist for Shirt Woot's science propaganda themed design contest.  Check out the other finalists here.

Wednesday, September 26, 2012

Blue lasers are blue

Sam Brown (a.k.a. Adam Culbert) at Exploding Dog Comics draws single-pane comics based on user-submitted titles.  I submitted a title to him via twitter in June of 2010 and was pleased to see it made into a comic.  


The phrase "I make lasers. They are blue." was inspired by my dissertation work on GaN-based laser diodes in the pure blue spectrum.  I used to think this drawing was a representation of the Icarus myth, which is perhaps appropriate because academic research can certainly have overabundant manifestations of hubris and tragedy. But the real reason I like it: it's a robot with friggin lazers shooting out of it's face.  

Check out Sam's other "lazer" themed drawings, of which I'm a fan.
If you're into the Icarus theme, check out his recent drawing, "The moon is big."

Monday, September 24, 2012

Lightbulbs and the Lumen

To help consumers shop for energy-efficient lighting products, the Federal Trade Commission explains the difference between watts and lumens.  Sort of.

To understand the difference between watts and lumens, you first need to understand a few fundamental properties of light.

The best way to think about light is as a wave of energy that travels through the air and bounces off things and then into your eyeball.  The difference between visible light and other kinds of wavy radiation in the electromagnetic spectrum, such as x-rays, microwaves and radio waves, is the wavelength -- the distance between the peaks of the wave, measured in meters.  Your eyeball has these rod and cone photoreceptor cells that just happen to be sensitive to a certain range of these wavelengths, which we call the visible spectrum.  Remember ROYGBIV?  Yeah, that.  

How bright something looks by your eyeball is related to (a) the rate of energy and (b) the wavelength

Radiant power or radiant flux is the total energy emitted over the entire electromagnetic spectrum, per unit time.  This power is in units of watts, the common unit that everyone is used to shopping for the old-school incandescent bulbs.  A 60 watt incandescent bulb consumes 60 watts of total electrical power and gives off approximately 45 watts of total radiant power (the other 15 watts are lost in the electronics).  

Yet, of these 45 watts of energy emitted from an incandescent lightbulb, most of it is completely invisible to the human eye.  That is, incandescents give off a whole bunch of light your eyeholes can't fucking see.  

Emission spectrum of an incandescent bulb (red dashed line) and human eye sensitivity (black dashed line) versus wavelength in nanometers (nm).  The visible spectrum ranges from around 390 nm (violet) to 700nm (red).  Longer wavelengths fall in the infrared (IR) range and shorter wavelengths are ultraviolet (UV).  

Only a small slice of the emitted "light" from an incandescent bulb falls in the range of wavelengths visible to the human eye (390 to 700 nanometers), and the rest falls in the invisible infrared (IR) range, as shown in the figure above.  An incandescent bulb is actually more efficient at making heat than light.

To complicate matters, the human eye does not see visible wavelengths equally.  The average daytime color sensitivity of your cone cells, shown above in the black dashed line above, a curve sometimes referred to as the luminosity function.  Your eye is most sensitive to wavelengths in the middle of the visible range, corresponding to green light.  It's just a nature of how your eyeball works.  Think of it as a filter that happens to pass more green light through your eyes to your brain.

Because the human eye is only sensitive to a small range of wavelengths, and some of those wavelengths more than others, we need another way to measure and represent useful light.  After all, a lightbulb will only appear bright if we can see the light it emits. 

Luminous power (also called luminous flux or photometric power), is a way to represent the power of light taking into account this wavelength-dependent sensitivity of the human eyeLuminous power is perceived radiant power.  Luminous power is the power of light you can actually see with your eyeball.  

The unit for this luminous power is the lumen (lm). To measure lumens, you must measure the total radiant power in watts for the entire range of wavelengths (the red curve above) and then take a weighted average with the luminosity function of the human eye (the black curve above).  The result of this mathematical magic is luminous power, which represents the perceived power of visible light.

For a standard 60 watt incandescent lightbulb, although most of the energy it emits is totally invisible, the output is still equivalent 800 lumens of visible light.

If you buy a compact fluorescent (CFL) or LED-based bulb rated at 800 lumens, that means it has the same luminous power and thus appears equally bright as a 60 watt equivalent incandescent bulb.  Their actual spectrum of energy they emit looks totally different, but the CFL and LED bulbs happen to use much less electrical power to achieve the same brightness of an incandescent, which is the whole fucking point!  

It turns out there a lot of technical jargon and complicated concepts when it comes to lighting products, but the US Department of Energy has designed new Lighting Facts labels for lighting products to make shopping easier.  I'll cover some of the other terms like color rendering index and color temperature in later posts.

You may have comments or questions, such as: 
 - CFLs are ugly and I hate them.
 - LED bulbs are also ugly and I hate them too.
 - Why is the sky blue?
 - Other
Leave a comment, and I will try to address it in a future post as well!

Sunday, September 23, 2012

Music that got me through college - Part 1

This is an understatement for those who know me well, but I was in college for a long time.  I started attending community college at 18 years old, bounced around two undergrad universities, then endured a long stint in graduate school before finally finishing my Ph.D just after my 33rd birthday.

Another understatement: I love music.  A LOT.  Music has been a constant companion of mine and certain bands, songs and albums will always remind me of particular times in my life.  And not in a general "this song reminds me of being 20" way, but specific moments, like "this song reminds me of moving into my first apartment."

This series, cross-posted to my music/miscellaneous blog, Auntie Cake, explores music that got me through my years as a college student.

Part 1. Community College  (1997 - 1999)
Memories of commuting to class and taking the scenic route, sitting in the dining room of my parents house while I plowed through Calculus or Physics homework, or on the computer chatting with geeky guys on IRC and obsessively reading online bulletin boards for The X-Files.  (Yes, I was still very much a virgin.)

The Cure - "A Forest"

R.E.M.  - "South Central Rain"

The Smiths - "What Difference Does It Make"

You might tell from the playlist that I was morose and a bit of a recovering goth.

x-posted to Auntie Cake

Thursday, September 20, 2012

DIY circuit boards & Cal Poly

This video from Make magazine shows you how to make your own printed circuit board using parts available from Jameco and other household items.  Neat!

As a Cal Poly undergrad, I took an Electronics Manufacturing class in the Industrial Manufacturing Engineering Department, a required course for electrical engineering majors.  The lab portion was more professionally equipped than this video but covered everything shown: CAD printed circuit board design, circuit board fabrication, and circuit assembly.  We also learned how to measure, cut, and bend metal sheeting to make housings for the final projects, typically a two-channel DC power supply. (I spray-painted mine purple.)

This video brings back memories of that class and how satisfying it was to design and build an electronics project from the design stage through the final product.  Some students hated it, probably because they had no prior experience soldering or handling power tools and really struggled, but I loved it!  In fact, I loved it so much I became a teaching assistant for the course for several quarters afterwards.

Cal Poly emphasized a lot of hands-on lab work, honoring the school motto: Discere Faciendo, or Learn by Doing.  My experience being a TA in electronics manufacturing gave me the confidence to dive into being a TA and lab assistant in grad school.  Unfortunately, a lab-heavy undergraduate curriculum can fall short on the academic and theoretical background required for graduate-level solid-state physics courses... which I later found myself woefully unprepared for.  Luckily, by the time you're a grad student, your GPA doesn't matter so much.  (Does it??)

Tuesday, September 18, 2012

GoldieBlox : An engineering toy for girls

Debbie Sterling, an engineering major from Stanford, has designed an engineering toy for little girls aged 5 - 9 called GoldieBlox.  Here's her Kickstarter campaign video to help raise money to see them into production.

"Any girl you know is so much more than just a princess."  

This is exactly what I was talking about in my last post.  It's so nice to see a real engineering toy for girls that's not just a hot pink version of a boys toy.

I dropped $30 to pre-order my own GoldieBlox kit (which will likely go to my niece).  I encourage you to show your support as well.

via Female Computer Scientist

Wednesday, September 12, 2012

There's No Such Thing As Calculus For Girls

Even on vacation, I gravitate towards my passions in life: good food, good beer, and science. My human boyfriend and I were in Cincinnati, Ohio over Labor Day weekend and killed some time between meals at the Museum of Natural History and Science at the beautiful Cincinnati Museum Center, which was offering free admission to commemorate the passing of local hero, Neil Armstrong. I especially enjoyed the ice age exhibit, which emphasized the idea that scientists are like detectives and use clues from nature to learn when and where glaciers formed, and how the environment and animal populations change over millions of years. I thought was a great way to introduce kids to the idea of objective observation.

Afterwards, we explored the museum gift shop where I noticed the "boys section" had several science-related items, such as the The Dangerous Book for Boys Electronics Science Kit.  Yet the "girls section," glaringly obvious by all the hot pink packaging, only had jewelry-making and fashion design kits.

Back the fuck up.

Why do the cool electronics kits have to be gender specific at all?  Why no "Electronics kit for kids?"

OK, I don't intend to needlessly pick on an otherwise nice museum. I understand the goal of the store is to make money and simply stocks whatever sells. I also understand that The Dangerous Book for Boys is merely a popular brand and that an equivalent Daring Book for Girls also exists. I will also admit that, unlike other female scientists, I will tolerate Computer Engineering Barbie and hot pink science kits for girls as long as they have a sufficient amount of science in them, and as long as there are plenty of other, gender-neutral science toys available to choose from.  Which, in this case, appeared to be none.

What offended me is that nowhere else in the museum would anyone be lead to believe that gender had any role in science.  A poster in the paleontology room, in fact, showed a picture of a female paleontologist.  These days, even academics can't get away with merely suggesting females might have innately different aptitude in math and science.

Boys and girls are taught in the same way, in the same classes, are equally adept, why should their access to educational toys be any different?  It makes me sad to think of some little girl wanting an electronics kit but feeling like she can't have one because the box it comes in is blue. 

Yes, women have achieved a lot in the past 100 years.  Yet most people probably don't even notice how ridiculous and old-fashioned our views on gender are, particularly in the messages we send kids on what they should be interested in.  Yes, some girls like Barbies, kitty cats and even the color pink, but sometimes they also love bugs, computers, chemistry, and science fiction.  It's possible to love both.

Marketing has it all wrong.  In science, it doesn't matter what gender you are.  Girls love science for the same reasons boys do.  

Science writer Jonah Lehrer explains all children are natural scientists.  It's in their nature to ask questions about the world.  As a scientist, they get to put on their thinking caps and investigate the answers in an objective way.  They get to use microscopes to look at really tiny things up close, or telescopes to look at really big things from far away, or mix two chemicals and see what happens, or dig in the dirt, or set things on fire.  Fascinating things.  A lot of experimentation is just plain fun.

The other great thing about science is that, even as a grown-up, it doesn't matter who you are, where you came from, what you look like, if you're shy, or even if you're not a straight-A student.  Like anything that requires problem-solving and collaboration, diversity is a good thing.  What matters most in science is your willingness to learn, work hard, and get your hands dirty.  It also matters that you have the confidence to keep going when you run into challenges. 

The problem isn't getting girls interested in science-- they are already interested.  The problem is keeping girls encouraged to stick with science despite the challenges, even when seemingly little things get in the way, like the toys they want are marketed for boys.  They might have long hair and prefer the color pink over other colors, but they aren't these delicate little things that can't handle advanced concepts, small parts, or complicated instructions too.  They should feel welcome and comfortable in the world of science from a young age, just as they are.  After all, there's no such thing as calculus for girls.

There IS such thing as a hot pink TI-84 graphing calculator.
(I kind of want one.)

Saturday, September 8, 2012

I started a new Twitter account

Follow me @postdocproblems