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It has been a long time since I wrote about my ongoing fight against cancer. A lot has happened in several months—many changes, several surprises, lots of ups and downs—and I have a backlog of half-finished posts that I hope to publish eventually. For now though, I wanted to write about one recent development and some interesting medical technology that I encountered because of it.

Last June I tweeted that one of my pupils was much smaller than the other. That medical mystery prompted several scans and tests. Unfortunately one of the scans revealed a small tumor in the back right of my brain. It is still a mystery whether that actually caused the problems with my eye, but it is obviously a(nother) serious problem.

I was strangely unbothered by the news. I already had tumors in my lungs and leg; what was one more when I was already undergoing chemotherapy? The problem is that the brain is protected by the blood-brain barrier that also prevents many chemotherapy drugs from acting on tumors in the brain. Fortunately, radiation therapy provides an alternative treatment for brain tumors, since the brain can withstand a larger dose of radiation than other tissues. My oncologist quickly referred me to a radiation oncologist. Within just two days, I had an appointment scheduled for radiosurgery.

There are several forms of radiosurgery, but all essentially bombard a tumor with a lethal dose of high-energy radiation. It sounds violent, but the treatment is noninvasive, painless, and has few side effects. The radiation oncologist recommended a particular technique/machine/brand called Novalis that is similar to the more widely-known (or at least better-marketed) Gamma Knife.

To hold the patient's head absolutely still and to calibrate the machine, it is necessary to brace the patient's head with a custom-molded plastic mask. The mask is made out of thermoform plastic mesh that is bolted directly to the table. Forming the mask was the most interesting part of a long day in the hospital.

The mask started at the back of the head. The technician laid a piece of the plastic mesh across a bracket, forming a headrest.

Next, two strips passed across the forehead and below the nose. Biting down on a small tab kept the upper jaw in place.

The strips formed the foundation for the mesh body of the mask.

The technicians heated all of the plastic pieces in a steaming vat of water. It started out transparent, malleable, and uncomfortably hot, but quickly cooled, solidified, and turned opaque.

With the mesh solidly in place, the technicians marked key points for calibration. During the treatment itself, they attached small infrared beacons (which looked like glossy silver marbles) to the calibration points, allowing the machine to precisely determine the location of the tumor.

The completed mask looked like a crocheted statue head and fit like a clamshell.

It took several hours for the radiation oncologist and technicians to plan the treatment itself. They combined two earlier scans with the new calibration points to calculate the precise path of the machine. When they finished, the treatment took just 20 minutes. I simply laid on the table, the technicians reattached the mask, and the machine made ominous buzzing noises. A followup appointment in a month should show whether the treatment was effective.

(Thanks, Dad, for taking pictures.)

Last April I bought a slide rule.

It is a Post model 1447 made by Sun Hemmi in Japan. I found it in an antique store buried under a pile of other slide rules and slide rule instruction booklets. Its beautiful bamboo-and-brass construction caught my eye, and I had to get it. As a computer scientist and programmer, so much of what I build is nonphysicial, so I love the idea of holding a physical computing device.

That is why I was especially excited when last week I came across the following book in the library:

It is called An Easy Introduction to the Slide Rule. I found it completely by accident. Only after taking it off the shelf did I notice the most surprising feature of the book: it was written by Isaac Asimov, he of science fiction super-fame.

The book explains the slide rule starting from first principles. It is informative and very enjoyable to read, even though some of the motivating stories show their age. Here is an excerpt from the first chapter:

We have all heard, these days, of electronic computers. These marvelous instruments, which came into use during World War II, are capable of performing in a few seconds work that might take years if all we could use were pen and paper.

There are times when arithmetical problems come our way and we might wish that we ourselves owned such a computer to do the work for us. Such a situation would have its disadvantages, however. Electronic computers are bulky, expensive, complicated, and can be handled only by people with special training.

Besides, electronic computers aren't at their best when used for everyday problems. That would be like trying to shoot a fly with naval artillery.

For a fly, an ordinary swatter is much better, and for ordinary mathematical problems, we could best use a really simple computer.

There happens to be a simple computer, just suitable for everyday computations, that was invented about 350 years ago. It isn't electronic; there are no electric currents involved. In fact, it is no more than a piece of wood with some marks on it. It looks like a ruler except that it has a middle piece that can slide back and forth, so that it is called a slide rule.

If a 45 year old book on slide rules sounds interesting to you (and how couldn't it!?), then you might also like How Round Is Your Circle, which explains how one would actually make a slide rule using nothing but a pencil, a piece of string, and three pieces of wood.

Update Tuesday, August 17, 2010

While antique shopping, I came across this handmade (!), four-foot-long slide rule.

The tag says, "For the slide rule collector who has everything, this is a home made demonstration classroom slide rule. I've had others that were company produced, but this is the first [that was made by hand]."

I would love to meet whoever made it. I would ask how he or she machined the hardware and determined the positions of the markings.

Today I got a new artificial leg.

It is hard to believe that it has been two years since I got my first permanent prosthesis. In that time, my leg has shrunk considerably, and I have gone through two other temporary legs. The size difference is remarkable.

I have written before about how these legs were made; in the following video, I show how this newest leg works.

Related

• Credit where it is due: all of my prostheses were custom-made by Ed and Mike at Advanced OrthoPro.
• The liner and locking mechanism are manufactured by Össur.
• Aimee Mullins discusses how her 12 pairs of prosthetic legs give her super powers

Two-factor authentication is a security procedure that verifies a user's identity using two pieces of information: one that a person knows (such as a secret password) and another provided by something he or she has (such as an ID card). Recently, VeriSign released an an iPhone application that provides a one-time password, enabling two-factor authentication on "40 web sites that are part of the VIP Network, including eBay, PayPal and AOL".

Two-factor authentication using a mobile device is an excellent idea. People rarely leave the house without their mobile phone, and as smart phones become more widespread, such an application could remove the need for easily-misplaced security tokens. But why just 40 websites? What the press release does not mention is that since VeriSign is an OpenID identity provider, the iPhone application can provide two-factor authentication for any site that accepts an OpenID login.

Fortunately, there is no reason why this kind of two-factor authentication must be tied to VeriSign. MyOpenID provides a service called CallVerifID that verifies identity with a call to one's mobile phone. The only thing still missing (as far as I am aware) is an open-source implementation independent of any third-party service.

Therefore, I make the following request to the LazyWeb. I use phpMyID on this website, making it my OpenID identity provider. It should be possible to make this simple application accept a second authentication factor provided by a mobile phone application. Any takers?

I have been around computers for my entire life. I remember playing DOOM across the home network; dialing into a bulletin board system on a 14.4 Kbit/s modem; helping my father install one of the first 1 gigabyte hard disks; and writing games in Excel's macro language. I recently came across two photos showing even earlier examples of the technology I had around me.

Here is a picture of my sister, father, and I using a cutting-edge (in 1987) Compaq 286. Obviously, my sister and I were already pair programming, 13 years before the advent of eXtreme Programming.

And here we are in 1988 playing a video game on our Commodore 64. Note the Atari joysticks.

What is your earliest memory involving computers?

Previously

• Personal recollections inspired by the book Grown Up Digital

In his book Grown Up Digital: How the Net Generation is Changing Your World*, Don Tapscott examines how technology has affected the "Baby Boom Generation" (born 1946 through 1964) and the "Net Generation" (born 1977 through 1997). My father, a Boomer, and I, a Net Genner, have always been heavily involved in technology, and this book echoes many of of our conversations about how we approach technology differently. In particular, the themes from the book reminded me of three stories: one about how ubiquitous technology becomes unremarkable, another about text versus voice communication, and a third about the shift from broadcast (i.e. television and newspapers) to participative media (i.e. the web).

It was around 1998 or 1999. My father, who has always been my family's technology evangelist and sysadmin, bought a WebTV for my grandmother, and I got to test it out at home for several days. I found out years later that most people hated the system due to its clumsy interface and poor website rendering, but at the time I greatly enjoyed surfing from the couch. When my parents asked what I thought about the gift, I remember saying, "she might find it useful, but, really, having the internet isn't such a big deal." I quickly rethought this statement. Even in those pre-Google, pre-YouTube, pre-blog days, my family already checked the weather forecast, read product reviews, and downloaded software updates online. I did not intuitively grasp the novelty and power of having instant access to a world's worth of information. In Grown Up Digital, Tapscott relates several similar stories in which technology has become "like the air", an unremarkable feature of the Net Generation's environment.

One such "unremarkable feature" is the mobile phone. Last year, half of the world's population carried a mobile phone. When people leave their home, all carry at least three things: their keys, money, and mobile phone. Because of this amazing growth, I always find it jarring to watch older movies in which the protagonist must find a pay phone to warn another character of impending doom. Similarly, the information systems in classic science fiction stories (say, pre-Neuromancer) seem faint and attenuated compared to today's dense and ubiquitous media. Interestingly, this seems to contradict the Net Generation's preference for text (i.e. short message service, instant messages, and email) over voice communication. Why do we communicate through low-bandwidth channels despite having high-bandwidth methods available to us?

Grown Up Digital mentions this tendency only briefly, but it is a characteristic I have noticed often and in many contexts. I think it appears because the web is inherently built around text, URLs, pages, and XML. To illustrate, I recently got a call from a friend I had not spoken to in several months. She and I talked for several minutes. During the conversation, I mentioned two YouTube videos I had seen, and she described her rock climbing club whose website she promised to send me. Then, the topic switched to a mutual friend who, since I had my laptop next to me (natch), I noticed was on AIM at the time. I suggested we hang up and resume talking online in a chat room I started. There, I sent her links to the videos, she sent me the club website, the mutual friend entered the conversation, and all three of us continued chatting for several times longer than we had been on the phone.

Just as person-to-person communication has been transformed by mobile phones, instant messages, and email, broadcast media is being supplanted by participative media such as websites, blogs, wikis, and aggregators. I find this the most exciting aspect of new media, and Grown Up Digital spends several chapters describing its effects on learning, institutions, business, family, and politics. One important effect has been that the Net Generation watches less TV than the Boomers (17.4 hours per week versus 22.4). The difference instead goes toward online activities. Clay Shirky calculates, for example, that Wikipedia alone required something like 100 million years of human thought, cognitive energy that would have otherwise languished watching sitcoms.

The same shift appears in my family's living room. I rarely just sit and watch. Instead, I usually have my laptop open, and my sister and I often IM silently across the room while my parents sit unaware. When watching a movie, I check reviews and trivia on IMDB; when watching a nonfiction program, I read about related topics on Wikipedia. However, I work better when I can devote my attention to a task, so when I need to focus, I, unlike many Net Generation multitaskers, tend to work in silence with my email and IM clients closed.

Grown Up Digital is filled with many other stories that resonate with my personal experiences. Further, it is all backed up with deep quantitative research and detailed citations. Its breathlessly positive assessment of the effects on society are reassuring, though I am surprised that the only major downsides voiced in the work involve online bullying and risks to privacy. What about the risks to content providers not from piracy but from an economy built on advertising? How can we ensure that the "Non-Net Generation" and those without access are not left behind? Nevertheless, I cannot wait to see what all generations can accomplish online.

* Forgive the Amazon affiliate link. It is something new I'm trying. If you click the link and buy something—it doesn't have to be Grown Up Digital—I get a small percent of the purchase price. And you get my gratitude.

On a private mailing list populated by my computer science friends, Sam asked the following question:

We're going to define the "future" as the first time a real space pirate hijacks a spaceship in space. The question is, how far away are we from the future?

A rousing and deep discussion ensued. Guesses ranged from 50 to 500 years, with an average around 200.

I think we are already in the future and better off not having to worry about space piracy, but that's a separate discussion.

The following is my slightly edited response to a comment about space pirates launching ships from the surface of the Earth (or another planet).

Let's address just the issue of getting into space. There are four ways to escape a planetary gravity well: chemical fuels, atomic energy, a space elevator, and some unknown future technology.

I always find it comical when science fiction writers send a small handful of people into space on top of a rocket. With the earth's dwindling reserves of fossil fuels and the rising environmental costs of burning them, I think one would agree that chemically-powered space travel will be limited in the future and certainly out of the economic reach of a small band of space pirates.

Since the atomic golden age of the 1950s and 60s, we have learned that atomic energy is too dangerous for individual use due to the danger of accidents and atomic weapons. (Aside: Find one of Eisenhower's "civilian atomic energy" videos online. They're hilarious.) I don't see this danger dwindling except by the invention of force shields or other defensive systems. Atomic energy also has the same fuel discovery and transportation issues as chemical rockets.

The deeper problem with both chemical rockets and atomic energy is that the ship must lift both its own weight and the weight of its fuel. This inefficiency makes a space elevator a much more believable method of moving cargo into space. In that case, the energy source remains stationary and must lift only the weight of the payload.

Thus, a space elevator removes the need for surface-to-space ships that space pirates could board and loot. Criminals could certainly infiltrate the elevator "cars" and steal cargo, but as I have explained above, it is unlikely they could get the cargo into space without their own elevator. Furthermore, such a crime stretches the common definition of "piracy" in which criminals hijack an independent vessel in transit.

It is likely that future technologies will provide alternate energy sources or completely new ways of traveling from a planet's surface into space. However, there will always be a lower bound to how much energy is required to lift a certain amount of matter out of a planetary gravity well in a particular amount of time. This is a substantial amount of energy no matter where it comes from.

For these reasons, I don't expect that space pirates will launch from the ground to intercept interplanetary cargo shipments. Instead, if interplanetary commerce ever becomes widespread enough to support piracy, I would expect pirates to stay in space and smuggle stolen cargo through a space elevator or other public transport system.

We have deep discussions like this all the time.

Indianapolis Executive Airport is a small, single-runway airfield that serves Hamilton County northeast of Indianapolis. On June 14, while driving to my parents' house to celebrate Father's Day and my sister's birthday, I happened to pass the airport during an open house benefiting the Indiana Down Syndrome Foundation. The event gave me a close look at three interesting helicopters: a Vietnam-era Huey, an Indiana State Police "eye-in-the-sky", and an air medical transport.

The Huey, serial number 70-16369, was an Army air ambulance deployed to Vietnam in 1971. It returned in 1972 and continued to perform air evacuations in South Carolina, Texas, Illinois, and Ohio until the Army retired it in 2001. At that point, the army transferred ownership to the not-for-profit Down East Emergency Medicine Institute in Maine, which used it for emergency search and rescue. In 2005, brothers John and Allen Walker purchased the helicopter, trailered it 1,300 miles to Peru, Indiana, and formed the not-for-profit American Huey 369 Organization to preserve the aircraft.

The Huey still flies, and one can purchase "memberships" that allow one to go on rides. When I arrived at the airport, the pilot was preparing to take a load of new members into the air.

I desperately wanted a turn. I spoke to an attendant and filled out one of the membership forms, only to be turned away when I pulled out my credit card. They only accepted cash or check.

An Indiana State Police helicopter, a Bell L3, number N54SP, was parked near the Huey. It is one of three helicopters in the state police's fleet of 14 aircraft. The pilot said he and the helicopter had come directly from helping helping flood victims south of Indianapolis.

A 1985 Eurocopter BK117, number N112LL, came last in the line of helicopters. It is one of four Lifeline helicopters operated by Clarian Health. Since 1979, it and the other Lifeline helicopters have transported more than 29,000 patients. The pilot said he averages about one flight per day and can range up to 150 nautical miles.

The back of the helicopter opens completely to allow access to the gurney. As one might expect, the cabin is filled with all sorts of medical supplies.

It was fortunate that I stumbled upon the open house. I found it fascinating to see these purpose-built machines up close and to talk to the pilots and crew.

Champaign's May 31 geohashing coordinates fell between the runways at Willard Airport, so I could not have made it without breaking several trespassing laws. Fortunately, I was also driving to Chicago for a concert, so I could take the back roads past Aurora, Illinois' graticule instead. The coordinates fell in a remote region of farms about an hour and 45 minutes directly north of Champaign.

The drive was sublime. The sky was clear, and the fields were just beginning to turn green. I had the windows and sunroof open the entire time.

Near Gibson City I saw dozens of wind turbines spinning on the horizon. I turned and drove to get a closer look. They were further away than I had expected; I drove at least five miles before meeting the first.

As I got closer, more and more turbines appeared over the treetops.

I had no idea that such a large wind farm existed so close to Champaign. According to Horizon Wind Energy, the Twin Groves Wind Farm, of which I saw only a part, covers 22,000 acres and produces 396 megawatts with 240 turbines. The American Wind Energy Association says that Twin Groves produces about half of Illinois' wind power.

After driving among the windmills like an ant among giant flowers, I resumed the trip north to the geohashing coordinates. The precise point fell in a cornfield near Campus, Illinois, population 145. To reach the field, I drove down a poorly-marked but well-maintained gravel road.

I was not surprised that no other XKCD readers were there since I arrived about 30 minutes late and the coordinates were so far away from everything. I did not hike into the field this time.

A pickup truck passed as I was getting back into my car. The driver rolled down his window and asked if anything was wrong. I thought about how I could explain geohashing but instead told him I just stopped to take some pictures.

From there, I slowly made it back to the main roads and arrived in Chicago in time for the concert.

Last week was spring break, and since The Paper consumed the first three days of my vacation, I was eager to make the remainder count. I have wanted to take a trip to Chicago ever since I became an Illinois resident, and I finally got my chance last week.

Most of the other CS grads either went on trips of their own or had work to do over break. Lucas, Zach, and I were all free and ready for a road trip. We left early— or at least early for graduate students— at 11 AM on Thursday. The trip started out windy and overcast, but steadily calmed and cleared as we drove north along US 45.

I love driving on back roads. The trip takes a bit longer since one must slow down for stoplights and villages, but the scenery and personality of the road make up for the lost time. I am fascinated by the fractal grouping of humanity that one encounters when driving down a state highway. On nice weekends, I will often choose a random direction and drive or bike until it gets dark or I decide to turn around.

However, I dislike city traffic as much as anyone else, so we picked up the interstate in Chicago's southern suburbs. From there we drove to a Park N' Ride where we caught a train into the city. I think this plan was ideal because parking was cheap and we did not have to fight with the crazy downtown roads.

We disembarked in front of the Art Institute of Chicago.

Since the day was beautiful—warm, sunny, and cloudless—we decided to walk around downtown.

First we walked through Millennium Park where we saw the famous (and incredibly photogenic) Cloud Gate sculpture and Gehry-designed amphitheater.

Then we walked along the entire Magnificent Mile on our way to lunch consisting of traditional Chicago deep-dish pizza.

After eating, we returned to the art museum. It has free admission Thursdays after five, so we walked right in and browsed until it closed at eight. I certainly could have spent all day there, but we saw many amazing works despite the shortened visit. Unfortunately I forgot to keep my camera when I checked my bag, so I do not have pictures. Zach, meanwhile, posted a whole lot.

We were all incredibly tired by the time we left the museum, so we took the train back to the car, then found a hotel in the suburbs.

On the second day we started early again (11 AM) and drove to the Museum of Science and Industry.

I am very interested in the history of science and technology, so I greatly enjoyed the museum's many technological artifacts.

Especially the old locomotives. Very steampunk.

The museum also had a very interesting automated assembly line that made little toys that children could buy.

After about three hours of browsing the exhibits, we queued up to enter Body Worlds 2. This was the best part of the trip. I was particularly amazed by a specimen/sculpture/exhibit that displayed all sorts of orthopedic hardware and another "exploded" man that reminded me of the Incredible Cross-Sections books.

We spent several hours browsing the bodies. Afterward, we had hoped to see The Second City, but learned that they were (unsurprisingly, being a Friday night) sold out. Having quenched our thirst for seeing the city, we began the trip back to UIUC.