At very the moment I was hemming and hawing over how to articulate my feelings about this development, someone used an AR-15 to murder twenty seven people, including twenty children, ages six and seven at Sandy Hook Elementary School. Now I know exactly how I feel.
I love 3D printing. I love the maker movement. I love the idea of people building home-brew versions of all sorts of devices, and inventing entirely new classes of devices. 3D printing has played, and will continue to play, an important role in that.
When I was fourteen, like many boys at that age, I thought missiles and fighter planes and tanks were pretty awesome. I read a lot of Tom Clancy books, and I indulged in my interest by dragging my family to the Wright Patterson Air Force Base Museum, the Smithsonian Air & Space Museum, the California Science Center’s Air & Space Museum, and the Intrepid Air, Sea & Space Museum. At Wright Patterson, I visited the F-117 Nighthawk as many times as I could. The author of Thing 11770 calls himself "Have Blue," the codename for the Nighthawk demonstrator aircraft.
When I was sixteen, I went to boarding school, where I learned vector calculus and farming. I learned how to grub potatoes out of the freezing ground in the driving rain, how to make maple syrup, how to lay in beets and squash and onions for the winter. I stood on a windy mountain top and learned how to find the orbital ephemera of a comet. I learned how to milk cows, how to care for cows when they are sick, and how to make the most delicious yogurt and mozzarella cheese you could possibly imagine. I learned how to repair a tractor engine with a mallet and a wrench. One freezing night, I found myself covered in blood and shit and urine and fear as I helped bring a new life gasping and staggering into the world.
Farming also means slaughtering and butchering. One morning, I walked into the barn. I was handed a weapon. I was asked to take a life.
I found that I could not.
The instant my shoulders took up the weight of the strange, snub nosed machine, it felt like the weight of the metal hung from my heart, stretching and distorting it. I wanted the weight of it to tear me apart, but I knew it was a weight I could carry, if I wanted to. I quietly handed the gun back to the farm manager, and walked out into the thawing snow, and spent the rest of the black pre-dawn puking into the mud behind the water tower.
Many people have wondered why I do not eat meat. This is why. For the rest of my life, I will feel the weight of that terrible little machine.
There are reasons to make, to have and to use guns. To defend your country, yes. To humanely put down an animal before butchering it, perhaps. For vainglory? For entertainment? No.
Tools are sacred things. We are a tool-using species; our tools are projections of our hopes and aspirations. When we are filled with joy, we pick up our tools and hammer the air into music. We need to understand and to be understood, and so we shape our voices into language. We send our tools delicately probing into the bodies of our loved ones, seeking out cancers and blood clots and infections. We invest huge amounts of effort building and maintaining tools that allow us to speak to one another across great distances. We hurl our tools across the void to other planets to satisfy our craving for knowledge. When we grieve, we take up our tools and carve the names of those we have lost into the living rock of our planet. Our tools are our souls. They are our defining characteristic. Love may be what makes us alive, but our tools are what make us human.
A gun is a tool. It is a simple tool. Any man or woman or child can use one. A gun is not much more complicated than a can opener, and not nearly as sophisticated as cordless screwdriver. Like all tools, a gun reveals something fundamental about its maker, its wielder and its abuser. This is true for all weapons.
As a strong supporter of the maker movement, of free and open source software, of open science, I want people to have as much freedom as possible to make and remake and experiment. I also believe very, very strongly in the responsibly we have to one another. I believe that we each have a responsibility not make things that hurt and kill and destroy.
I am not yet prepared to call for a law to prohibit Have Blue from posting functional 3D printable assault rifle parts on the internet. The law is a blunt instrument, and would cause a great deal of collateral damage. However, I am prepared to say that Have Blue is a fucking asshole. I am prepared to call Justin Halford, who created the original CNC model, a fucking asshole. I am prepared to say that anyone who considers themselves a "gun enthusiast" and is older than about sixteen needs to grow the fuck up. The maker community should not tolerate this behavior. Meditate on the meaning of the word antisocial for a moment. What could be more antisocial than gleefully proliferating machines whose principal function is murder?
The maker community should not tolerate these designs, or the ideas and opinions of their designers until they show evidence of behaving like adults. It's clear that the CNC Gunsmithing community has a lot of talented, clever people. It's clear from reading his blog that Have Blue is neither ignorant nor stupid.
So, I'm calling you folks out. There are twenty children dead in Connecticut. Their bodies were ripped apart by the very machines you are "democratizing." As far as I know, nobody has used your designs to kill anyone. If you continue down this path, some future version of Thing 11770 will be used to murder little children. It's just a matter of time, and probably a lot less time than you think. However, there is still time to take a stand. Do the right thing. Take down the designs. Apologize for what you've done. Find a new project. Use your talents for something good. This will not stop people from murdering children with 3D printed guns, but perhaps you can buy us some time before that day comes. You know that this is true.
If making home-brew assault rifles is really what you want to do, there is perhaps one venue where this might actually make sense. Freight your CNC machine to Istanbul, and smuggle it into Homs or Aleppo. Help the Free Syrian Army get rid of Bashar Assad. Oh wait, what’s that? You don't want to get shot? Fancy that.
It takes courage to admit you are wrong. Show us some courage.
Update : It appears that MakerBot has decided to remove Thing 11770 from Thingiverse. If you follow the link to the item, the files have been removed and a message says, "This Thing is currently under moderation for violating the Thingiverse Terms of Service. Files and images for this Thing are currently unavailable." I'm glad it's no longer up, but I am disappointed in how this was handled. I'm disappointed that MakerBot left it up for so long, but I'm also disappointed that Have Blue didn't just take it down himself.
Since then, the intersection where she died has been redesigned. It is now a three-way stop with modern LED lighting. Watching over the scene, there is a new flashing red beacon.
This sort of infrastructure is easy to take for granted. As a Commissioner for the City of Davis, I suppose I pay closer attention to these things that most people do. I've payed particular attention to this little piece of city infrastructure because I pass through it several times a day.
Something has changed there since the red beacon went up. Up and down the boulevard, for almost a mile, there are crossings to access the bicycle path. Drivers now stop and let me cross. They never did that before. I am not exaggerating when I say that wherever the beacon's light falls, the feel of the street has changed. It's no longer the tail end of a lonely country road. It's a neighborhood street, and people act accordingly.
I would like to think that drivers feel the significance of the flashing beacon. I would like to think that they have noticed that the intersection has been redesigned. I would like to think that they know that Megan Glanville died there. In all likelihood, they are oblivious to these things. They stop and smile and waive me through anyway.
Good design matters. That's why.
The rocky ledge runs far into the sea,-- The Lighthouse, Henry Wadsworth Longfellow
And on its outer point, some miles away,
The Lighthouse lifts its massive masonry,
A pillar of fire by night, of cloud by day.
Even at this distance I can see the tides,
Upheaving, break unheard along its base,
A speechless wrath, that rises and subsides
In the white lip and tremor of the face.
And as the evening darkens, lo! how bright,
Through the deep purple of the twilight air,
Beams forth the sudden radiance of its light
With strange, unearthly splendor in the glare!
Not one alone; from each projecting cape
And perilous reef along the ocean's verge,
Starts into life a dim, gigantic shape,
Holding its lantern o'er the restless surge.
Like the great giant Christopher it stands
Upon the brink of the tempestuous wave,
Wading far out among the rocks and sands,
The night-o'ertaken mariner to save.
On a superficial level, a flashing red beacon is a utilitarian thing. If you look more closely, you will see that it is also a thing of beauty. It is an avatar of the compulsion we all feel to protect, to warn, to guide. The humble beacon is one of the better angels of our nature, sculpted with massive limbs of galvanized steel and eyes of electrically exuberant gallium phosphide. It sends our message out into the world, again, and again, and again.
I find it extremely frustrating that most people do not look beyond the (usually imagined) behavior of the people involved in an accident like the one that almost killed my sister, or that did kill Megan Glanville. Either they identify with the frustrating experience of driving, and blame the victim, or they side with the law, and place the responsibility at the feet of the operator of the more dangerous vehicle. I will always side with the person who suffered more, but both views are myopic. When someone has been killed in an accident, the question of who was more "right" in that sliver of time is irrelevant. It is worse than irrelevant; it is an insult to the lives of all the people affected.
There are other, far more urgent questions that need to be raised. If you see a problem, the first question you should always ask is, "In what way am I responsible for this?" We are all bound together by bonds of mutual responsibility, and nothing happens among people, good or bad, for which each of us are not in some sense responsible. That is what words like "society," "community," and "civilization" mean. They describe the fact that the bonds that link us together are fundamentally inescapable. There is such a thing as integrity, but there is no such thing as self-reliance. Interdependence is the very essence of what makes us human. And so, if you see something that upsets you, the first thing you should look at is your own role in causing it. Through our choices, we were all present on morning that George Souza killed Megan Glanville. You. Me. Everyone. We all had a hand in it.
Clearly, we failed. You failed. I failed. Someone is dead as a consequence of that failure.
So, let us set aside the choices of George Souza and Megan Glanville, and look at the choices we made that contributed to this terrible thing. They are easy enough to see :
This is the crosswalk where Megan was killed, which is part of a system of roads that belong to the City of Davis. The arrow on the yellow sign is pointing almost directly at the spot. The laws that govern the design of the road are a kaleidoscopic fugue of local, county, state, federal and international regulations. Within that often contradictory matrix of statutes, the city government has a small keyhole of authority within which it may choose what the road looks like and how it works.
From an engineering point of view, it's pretty clear what the problem is. The road on the left is just a stone's throw from the border of the city. Beyond the border, it is a wide county road that cuts a nearly straight line for miles among orchards and farms. When it crosses into the city, this road suddenly plunges into a dense residential neighborhood with no transition whatsoever. The intersection where Megan was killed is the very first intersection an eastbound driver encounters in the City of Davis. So, drivers come in from the county road going at county road speeds, and roar through this intersection where people are trying to cross to the bike path that parallels the road. Add a little darkness and bit of fog, and the accident was basically inevitable.
Why was this intersection designed this way? I don't know. According to the laws and statutes that regulate its engineering, there is nothing particularly wrong with it. But then again, houses that catch fire and burn people alive inside are often built to code. Compliance with the law is not enough. Only thoughtful design can keep people safe, and the absence of that thoughtfulness killed someone.
So, who is to blame? The legislators who wrote the statues describing how intersections should be designed? The engineers whose designs were constrained by those statutes? The City of Davis Public Works Department that built and maintained it? Surely, some of the responsibility falls to them. But not very much. If you've ever driven, walked or bicycled through the intersection of Lake and Russell, then a great deal of the responsibility falls on you. If you've ever felt uncomfortable or unsafe while passing through it, then you knew someone would get hurt there sooner or later.
The Council Chambers are open to the public. The meetings and agendas are available weeks in advance for all to see, at CityOfDavis.org. You can even submit your concerns in writing if you don't have time to come to the meetings. In other words, you had the reason and the means to get this fixed, or at least play a part in getting it fixed, before Megan Glanville was killed. I share in this responsibility; I serve on the commission charged with advising the City Council on these things, and I did not raise this issue either. And I use this intersection several times a day. And I always feel unsafe. It is my fault too.
So, here is what is going to happen. The City Council was asked, and agreed, to take steps to prevent anyone else from getting killed. The proposed changes will add stop signs on Russell Boulevard in both directions, a blinking red light in case drivers don't see the stop signs in the fog, and four new street lights for better illumination overall. It will cost about $20,000.
This is a much better design. It's impossible to know if it would have saved Megan's life had it been in place in December, but it seems likely that it would have. I strongly support it.
Roads are not natural phenomena. They are public infrastructure, and they are designed and built and maintained in exactly the way the public asks them to be. Let's try to do a better job of holding up our end of that conversation.
As for me, I'm writing this post for the girl on the Dover train who gave me a funny look. Um... Hi.
Don't know if this will work, but stranger things have happened.
For my mom's birthday, she and my sister came over and slept on the floor of my apartment in Davis, despite the availability of perfectly comfortable and reasonably priced lodgings downtown. For her birthday, we found a fetid puddle of water near Lake Berryessa with some tadpoles in it. She was delighted.
For my dad's birthday, he's celebrating his election to the National Academy of Engineering (the sister organization to the Institute of Medicine. He also got this birthday card from his longtime college friend Bruce Reznick :
Bruce is a professor of mathematics at the University of Illinois. He studies the identities of high-order polynomials. So, this really is the a birthday card only he would think to send.
That is all.
Haw! This thing is cool.
The speaking docket got shuffled around a lot, and I ended up having to give my talk much earlier than planned. I suppose this is the inevitable downside of procrastination. While I was scrambling to finish it, I didn't have much time for blog updates!
I survived the talk. There were lots and lots of excellent questions, and I have a lot to think about now. Anyway, back to the updates from Uzon.
Panorama overlooking Orange Fields in Uzon Caldera
We just arrived back in Petropavlovsk after a week in the field. I was very sad to leave Uzon, and it was a privilege and an honor of the highest order to have spent those days there.
The expedition was, I think, a great success. We'll know for sure once we're back at our labs and can use more sophisticated methods to examine our samples. I am very confident, though.
It was a bit touch-and-go right at the end. Our high speed centrifuge crapped out last night, just as Sarah was in the middle of the last big run of DNA extractions. The Russian team brought their own centrifuge, but we couldn't run it on our generator. Much to our relief, Albert was able to magically get the thing working again by holding it at just the right angle. They worked through the night to finish processing the samples; I think Albert must have had his thumb wedged under the centrifuge for the entire run.
I'm sorry I wasn't able to send many Twitter updates toward the end of the expedition. Once I had identified my sampling targets, I suddenly had a lot less free time on my hands (and I didn't have much to begin with). Also, I'm sorry for updating in ALL CAPS. Iridium handsets are essentially 1993 technology. Composing text messages is extremely painful, and the battery only lasts long enough to compose two or three of them. This is a pain when you have to recharge on generator power, and the generator only cranks up for a few hours a night, and even then only to power lab equipment for DNA extractions. Hats off to my dad for relaying the messages!
Right now, I'm sitting in a friendly internet cafe in Petropavlovsk where they've let me use their wireless connection. When we arrived at our crowded little apartment, the hot water was broken, and thus no showers yet. A wide selection of interesting geologic samples are wedged under my fingernails, and I think I have wads of some sort of hardened liquid sulfur caked in my hair. The helicopter arrived ridiculously early, and we just barely get everything aboard. As a result, I'm still wearing my field clothes from yesterday, which are splattered with volcanic mud. I may actually be the worst-smelling person in Petropavlovsk. Perhaps it is fortunate that this internet cafe caters mainly to kids playing StarCraft.
I composed blog entries for each day we were in Uzon, and I'll be posting them as soon as I run them past the rest of the team. I also have almost two thousand photos to sort, tag and upload.
That said, I have a correction for one of my Twitter updates. I wrote :
YERTERDAY ALBERT & TEAM WERE CHASED AWAY FROM A SITE BY A BEAR THAT WAS ACTUALY A BUSH IN THE FOG.Albert pointed out that they were interrupted for a few minutes, but not actually chased away. He stepped forward and shouted see if he bear (or bears) would go away, with his signal torch uncapped and ready. The bears were revealed to be bushes as the wind shifted and created a channel in the mist. It's funny, but given how foggy it was that day, it wasn't actually that surprising. We were at the same site the next day, and were surprised by an actual bear. It wandered pretty close to us before we could actually see it (the full story will come with the article for that day).
A bear interrupting important EisenLab work at Boiling Spring.
Update : Albert also says that I'm wrong about having to wedge his thumb under the centrifuge the whole time. It started working again after shaking it around in the air a bit, and placing it just so on the table. He only had his thumb wedged underneath it for a minute or two to check to see if it was overheating.
I've been working on the analysis of environmental samples from two sites at Uzon Caldera (about 10,000 Sanger reads from each sequenced at the JGI), and I'm hoping that I'll be able to reprocess the DNA here at the UC Davis Genome Center using some of our high-throughput machines. Licensing and customs restrictions will probably make it impossible to bring my own samples back, but I may be able to entrust them to a colleague with fancier credentials than my own.
Insofar as it will be possible, I will be blogging from Kamchatka and uploading photographs and data, so please ask questions in the comments!
I'll be arriving in Petropavlovsk on the 30th of July, with the help of a generous grant from the Carnegie Institution for Science Deep Carbon Observatory.
I hate giving blood. They didn't need very much, but I don't get along very well with steel needles. I count it as a major victory that I didn't barf until I got home.
Now we all wait for the results.
Good luck, whoever you are.
My twenties; better than my teens. Some good times, and some pretty awful times, and on average kind of meh. If the trend holds, my thirties should be in the tolerable to nice range. Hopefully the underlying process is geometric, and not linear or logarithmic.
Hence the awkward sort of half-smile.
I will miss her terribly.Terry Young: She is gone Sent: 2:54PM
It's actually quite useful to have this data, especially if it's correlated with some richer information. For example, I've consulted the data to answer questions like, "Where was that awesome sandwich place I ate at last month?" It's also extremely useful to be able to share this data with Google because it allows me to quickly cross-reference location coordinates with Google's database of businesses and addresses. You can also download your complete location history in one giant blob (just ignore the warning that the History map only displays 500 datapoints, and download the KML file). Once you have the KML file, you can do whatever you want with it. For example, I uploaded mine to Indiemapper to map my wanderings for the last six months (Indiemapper is cool, but I quickly found that this dataset is really much too big for a Flash-based web application).
Not surprisingly, I spent most of my time in California, mostly in Davis and the Bay Area, with a few trips to Los Angeles via I-5, the Coast Starlight, and the San Joaquin (the density of points along those routes is indicative of the data service along the way).
The national map shows my trip to visit my dad's family in New Jersey and Massachusetts, as well as a layover in Denver that I'd completely forgotten about.
I have somewhat mixed feelings about this dataset. On one hand, it's very useful to have, and sharing it with my friends and with Google is very useful. It's also cool to have this sort of quantitative insight into my recent past so easily accessible. On the other hand, I'm not particularly happy with the idea that Google controls this data. I chose the word controls deliberately. I don't mind that they have the data -- after all, I did give it to them. As far as I know, Google has been a good citizen when it comes to keeping personal location data confidential. The Latitude documentation makes their policy pretty clear :
So, that's what they'll do with it, and I'm happy with that. What bothers me is this: Who owns this data?
PrivacyGoogle Location History is an opt-in feature that you must explicitly enable for the Google Account you use with Google Latitude. Until you opt in to Location History, no Latitude location history beyond your most recently updated location if you aren't hiding is stored for your account. Your location history can only be viewed when you're signed in to your Google Account.
You may delete your location history by individual location, date range, or entire history. Keep in mind that disabling Location History will stop storing your locations from that point forward but will not remove existing history already stored for your Google Account.
If I delete my history, does Google keep a copy or can I recover it?
No. When you delete any part of your location history, it is deleted completely and permanently within 24 hours. Neither you nor Google can recover your deleted location history.
This question leads directly to one of the most scorchingly controversial questions you could ask for, and there are profound legal, social, economic and moral outcomes riding on how we answer it. This isn't just about figuring out what coffee shops I like. If you want to see how high the stakes go, buy one of 23andMe's DNA tests. You're giving them access to perhaps the most personal dataset imaginable. In fairness, 23andMe has a very strong confidentiality policy.
But therein lays the problem -- it's a policy. Ambiguous or fungible confidentiality policies are at the heart of an increasing number of lawsuits and public snarls. For example, there is the case of the blood samples taken from the Havasupai Indians for use in diabetes research that turned up in research on schizophrenia. The tribe felt insulted and misled, and sued Arizona State University (the case was recently settled, the tribe prevailing on practically every item).
You can't mention informed consent and not revisit HeLa, the first immortal human cells known to science. HeLa was cultured from a tissue biopsy from Henrietta Lacks and shared among thousands of researchers -- even sold as a commercial product -- making her and her family one of the most studied humans in medical history. The biopsy, the culturing, the sharing and the research all happened without her knowledge or consent, or the knowledge or consent of her family.
And, of course, there is Facebook -- again. Their new "Instant Personalization" feature amounts to sharing information about personal relationships and cultural tastes with commercial partners on an op-out basis. Unsurprisingly, people are pissed off.
Some types of data are specifically protected by statute. If you hire a lawyer, the data you share with them is protected by attorney-client privilege, and cannot be disclosed even by court order. Conversations with a psychiatrist are legally confidential under all but a handful of specifically described circumstances. Information you disclose to the Census cannot be used for any purpose other than the Census. Nevertheless, there are many types of data that have essentially no statutory confidentiality requirements, and these types of data are becoming more abundant, more detailed, and more valuable.
While I appreciate Google's promises, I'm disturbed that the only thing protecting my data is the goodwill of a company. While a company might be full of a lots of good people, public companies are always punished for altruistic behavior sooner or later. There is always a constituency of assholes among shareholders who believe that the only profitable company is a mean company, an they'll sue to get their way. Managers must be very mindful of this fact as they navigate the ever changing markets, and so altruistic behavior in a public company can never be relied upon.
We cannot rely on thoughtful policies, ethical researchers or altruistic companies to keep our data under our control. The data we generate in the course of our daily lives is too valuable, and the incentives for abuse are overwhelming. I believe we should go back to the original question -- who owns this data? -- and answer it. The only justifiable answer is that the person described by the data owns the data, and may dictate the terms under which the data may be used.
People who want the data -- advertisers, researchers, statisticians, public servants -- fear that relinquishing their claim on this data will mean that they will lose it. I strongly disagree. I believe that people will share more freely if they know they can change their mind, and that the law will back them up.
UpdateThe EFF put together a very sad timeline of Facebook's privacy policies as they've evolved from 2005 to now. They conclude, depressingly :
Viewed together, the successive policies tell a clear story. Facebook originally earned its core base of users by offering them simple and powerful controls over their personal information. As Facebook grew larger and became more important, it could have chosen to maintain or improve those controls. Instead, it's slowly but surely helped itself — and its advertising and business partners — to more and more of its users' information, while limiting the users' options to control their own information.
Oddly, the fleas don't seem to like Neil very much, nor do they like me. It's just poor Buzz that's beset by the nasty little critters.
Figure 1: A flea.
As it happens, I've been thinking about endogenous metrics for estimating the sampling quality of an environmental shotgun sequencing dataset, and Buzz's little problem presented an opportunity to play with a simplified problem. So, I have decided to make Buzz, or rather his fleas, into a small experiment in ecology. I am going to try to see if I can drive them into extinction.
Now, this is normally what a pet owner does when they discover their pet has contracted some sort of annoying parasite, but I decided to take a more quantitative approach.
Figure 2: A cat.
It's simple enough to count fleas on a cat, if the cat is willing to cooperate. Buzz loves the flea comb, and will gleefully hop onto the coffee table and wait to be combed if you show it to him. So, in the interest of science, I convinced my roommate to count the number of passes I made with the flea comb and how many fleas I captured (posterity will remember your efforts, Mehdi). Using his tally, I plotted the cumulative number of passes verses the cumulative number of fleas.
Figure 3: Fleas captured
As expected, it became somewhat more difficult to capture the next flea as more fleas were captured, suggesting a depletion curve. The value of the asymptote should be the actual number of fleas on Buzz at the time, and reaching that number would imply local extinction for the fleas. Of course, there are probably other fleas lurking about that would recolonize Buzz. In principle, if I were to repeat the exercise frequently enough, Buzz would become a sink for fleas, and their migration to his fur would gradually deplete them from the environment.
There are a couple of different ways to model the impact of the combing on the flea population, with various advantages and disadvantages. All we really want to do here is to estimate the value of the asymptote, and so a simple model is probably sufficient. I showed this data to my fried Sharon Shewmake, an economics graduate student. Sharon, after editorializing on the endeavor ("Ew."), suggested this very simple model.
Assume that Buzz is not going to sit still long enough for the fleas to reproduce, for more fleas to migrate to his fur, and that the fleas already on his fur are going to stay put unless captured. Thus, there is a fixed initial population which only changes as a result of capturing fleas. Next, we assume that any given flea is equally likely to be captured on a single pass of the comb. So, the expectation value for number of fleas captured on a single pass is the product of the current population and the probability of capturing a flea.
where N is the population of fleas and p is the probability of any particular flea being captured on a single pass. One could tart this up a bit by modeling it as a stochastic process and executing a bunch of Monte Carlo trials until the outcomes converge, but that seems like overkill for a simple single variable problem like this. We will put up with the intellectual inconvenience of capturing fractional fleas.
This is a little easier to see if we let N represent the number of fleas remaining on the cat, rather than the number of fleas captured.
If we stretch our credulity far enough to imagine this as a continuous function, we can express it as a differential equation.
Sorry if this bothers you. Not only are we extracting fractional fleas, but we are now modeling the combing process as a sort of flea-killing-combine continuously mowing its way through the fur. This is a model, so you shouldn't be surprised to find massless rope and spherical cows. Anyway, it has a nice easy solution.
Well, what the heck. This is a decaying function, so let's pluck a minus sign out of the exponential factor, and maybe tack on a scale factor for the initial population.
While we're at it, why don't we go back to letting the function stand for the number of fleas captured, rather than the fleas on the cat.
This gives us a nice function to use for a linear regression. A little help from scipy, and we find that the initial population is estimated at 39.7 fleas, and the decay factor is 0.011.
Figure 4: Flea population
I captured 34 fleas, so that means I missed about five or six. In order to be reasonably confident that I'd captured all 39 fleas, I would have had to continued for about 400 passes with the comb, instead of 173. Buzz is a patient cat, but he started to loose interest around 120 passes, and had to be fetched back onto the coffee table a few time times during the last 50 passes. My guess is that 400 passes would require some kind of sedative. On the other hand, he does seem to like Guinness, so there may be something to that.
Science has been served. I'm going to the pet store to buy some flea collars.
I'm still getting the hang of getting a decent pull of espresso out of it. I've found that my burr grinder doesn't quite go fine enough for espresso, so I'm going to have to take it apart and see if I can adjust the grinding wheels so they're closer together. Anyway, here is my latest effort :
Even asleep, Neil seems to understand.
I normally don't talk a lot about my personal life on my blog, and except for the occasional announcement, I'd like to keep it that way. People's little triumphs and tragedies are mainly interesting to those directly involved, and are at best kind of boring to everyone else. A lot of my friends and family do read this blog, but by and large most of you are strangers or acquaintances. I try to respect that.
Those of you who are close to me know that I'm going through a sad time in my life right now. Those of you who work or study with me have probably noticed that I've not been my usual cheerful self. In deference to the many people who aren't here to read about that, and the fact that I can barely think about it (never mind write about it), I'm not going to discuss what's happened on my blog.
The one thing that has helped has been hearing about all the cool things that other people are doing. So, even though I'm not exactly Mr. Social right now, please don't take that as a sign that I want to be left alone.
On the contrary. Now would be a great time to tell me about whatever is on your mind, especially if it's cool.
To those of you who've been kind enough to treat me like a normal person over the last two weeks despite my melancholy behavior, I owe you guys. Really.