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Saturday, June 18, 2011

Sewers hold the secrets of the city

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Sewers hold the secrets of the city


Your toilet knows what you did last summer.

Apparently, one way to estimate drug-use rates in a city is to tap into its sewers. The city of Oslo did this with what's called a Passive Sampler—filters that continuously collect samples of chemicals in the environment. After several weeks, old filters are replaced with new ones and the collection membranes are taken to a lab and analyzed with mass spectrometry. The same system has been used to look for pollution near oil derricks. But it can be configured to check for other substances, too.

For instance, in Oslo, levels of the drug ecstasy spiked in the city's sewer water, increasing 10 fold, during the two weeks when Norwegian teenagers celebrate high school graduation.

Image: Toilet.CapitolHill.SE.WDC.22sep05, a Creative Commons Attribution (2.0) image from perspective's photostream

[Richard Dawkins]: Sex selection and the shortage of women: is science to blame?

[Lots of interesting food for thought. -egg]

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[Richard Dawkins]: Sex selection and the shortage of women: is science to blame?

A couple watch their baby inside a waiting hall at the Nanjing railway station, capital of Jiangsu province. [Reuters/2006]

In nature, the balance of males and females is maintained by natural selection acting on parents. As Sir Ronald Fisher brilliantly pointed out in 1930, a surplus of one sex will be redressed by selection in favour of rearing the other sex, up to the point where it is no longer the minority. It isn't quite as simple as that. You have to take into account the relative economic costs of rearing one sex rather than the other. If, say, it costs twice as much to rear a son to maturity as a daughter (e.g. because males are bigger than females), the true choice facing a parent is not "Shall I rear a son or a daughter?" but "Shall I rear a son or two daughters?"

So, Fisher concluded, what is equlibrated by natural selection is not the total numbers of sons and daughters born in the population, but the total parental expenditure on sons versus daughters. In practice, this usually amounts to an approximately equal ratio of males to females in the population at the end of the period of parental expenditure.

Note that the word 'decision' doesn't mean conscious decision: we employ the usual 'selfish gene' metaphorical reasoning, in which natural selection favours genes that produce behaviour 'as if' decisions are being made.

Interestingly, Fisher's reasoning remains intact, even in harem-based societies such as those of elephant seals, where a minority of males monopolise the females and the majority of males hang about as disconsolate bachelors. From a parent's point of view, a daughter is a 'safe' choice, likely to yield an average number of grandchildren. A son is a high risk choice. He is most likely to give you no grandchildren at all. But if he does give you grandchildren he'll give you lots. The figures balance out and Fisher's equilibrium still holds.

That's what happens in nature. But what if we are dealing with a human society in which cultural traditions over-ride the genetic imperatives (yet another example, this time not necessarily a benign one, of 'rebelling against the selfish genes'). What if the religion of a country fosters a deep-rooted undervaluing of women? What if there is an ancient culture of despising women, whether for religious or otherwise traditional or economic reasons?

In past centuries such cultures might have fostered selective infanticide of newborn girls. But now, what if scientific culture makes it possible to know the sex of a fetus, say by amniocentesis or ultrasound scanning? There is then an obvious temptation selectively to abort female embryos, which could have far-reaching and probably pernicious social c...

Thursday, June 16, 2011

Bubble-in forms betray individual, traceable "handwriting"

Bubble-in forms betray individual, traceable "handwriting": "

Original research from Princeton's Joe Calandrino, Ed Felten and Will Clarkson show that machine analysis can make very accurate guesses about the identity of people who complete bubble-in forms -- that is, there's something like a recognizable, individual 'penmanship' for the small scribbles used to fill in the bubbles on machine-readable forms.

These individuals have visibly different stroke directions, suggesting a means of distinguishing between both individuals. While variation between bubbles may be limited, stroke direction and other subtle features permit differentiation between respondents. If we can learn an individual's characteristic features, we may use those features to identify that individual's forms in the future.

To test the limits of our analysis approach, we obtained a set of 92 surveys and extracted 20 bubbles from each of those surveys. We set aside 8 bubbles per survey to test our identification accuracy and trained our model on the remaining 12 bubbles per survey. Using image processing techniques, we identified the unique characteristics of each training bubble and trained a classifier to distinguish between the surveys' respondents. We applied this classifier to the remaining test bubbles from a respondent. The classifier orders the candidate respondents based on the perceived likelihood that they created the test markings. We repeated this test for each of the 92 respondents, recording where the correct respondent fell in the classifier's ordered list of candidate respondents.

New Research Result: Bubble Forms Not So Anonymous


Is the world ready for this jelly?

Is the world ready for this jelly?: "Idontthinkyoureready.jpg

You can't tell from the photo, but this jellyfish is huge. Nomura jellyfish, native to the waters off China and Japan, can grow to be the size of a refrigerator, and weigh up to 400 pounds. And, since the 1990s, there's a lot more of them. Swarms, 500 million jellies strong, have sunk ships, writes Brandon Keim in Wired. It's part of a global increase in jellyfish populations. Right now, nobody's sure whether this is a blip, or a new normal. But everybody would like to know how jellyfish affect ecosystems, and new research offers some sobering analysis.

In what may be the most comprehensive jellyfish study to date, Condon's group spent nearly four years gathering data from Chesapeake Bay on Mnemiopsis leidyi and Chrysaora quinquecirrha, two species that have caused trouble elsewhere and are considered representative of jellyfish habits worldwide.

The researchers counted them at sea, measured the nutrients in surrounding water, and calculated the composition of nearby bacterial communities. In the lab, they observed how bacteria in seawater reacted to jellyfish, and tracked chemicals flowing through their aquariums.

They found that jellyfish, like many other marine species, excrete organic compounds as bodily wastes and as slime that covers their bodies. But whereas the excretions of other species are consumed by bacteria that form important parts of oceanic food webs, jellyfish excretions nourish gammaproteobacteria, a class of microbes that little else in the ocean likes to eat, and that produces little of further biological use.

'Lots of marine creatures make this dissolved organic matter that bacteria use to live. But the point of this paper is that the organic matter produced by jellies doesn't make it back up the food web,' said study co-author Deborah Steinberg, also a Virginia Institute of Marine Science biologist. 'When jellies are around, they're shunting this energy into a form that's just not very usable. They're just shunting energy away from the rest of the food web.'

Nomura jellyfish photo by KENPEI, used via CC


NYC cyclist vs. bike lanes - kamikaze law-abiding

NYC cyclist vs. bike lanes - kamikaze law-abiding: "

A NYC cyclist who received a fine for straying out of the bike-lane recorded this video of his attempt to ride around town without leaving the bike-lane, instead crashing merrily into any obstacle that he encountered, from taxis to construction equipment.

Guy Crashes Multiple Times To Make Point About NYPD Ticketing Bicyclists


Very bad late '90s hip-hop cover art

Very bad late '90s hip-hop cover art: "90shiphopart.jpg

An academic appreciation of very bad late '90s Hip-Hop cover art. (thanks, David)


3D printed trigonometry calculator

3D printed trigonometry calculator: "

Lalbritton's 'Ideal Harmonic Transformer' is a 3D printed mechanism for calculating sines and cosines: '
It is a thing to hold, enjoy turning the crank, and look at. If you can't find your calculator, and need to know the sine or cosine of an angle real quick, you can dial in the angle and read off of the Scotch Yokes. It also works in reverse.'

Ideal Harmonic Transformer by lalbritton

(via Make)


White man from Georgia is "Gay Girl from Damascus"

[Watch! As the very concept of identity dissolves before your very eyes! -e]
White man from Georgia is "Gay Girl from Damascus": "


For weeks, journalists, bloggers, and human rights advocates have been trying to track down a 'disappeared' mideast blogger named Amina, who identified herself on her blog as a 'Gay Girl from Damascus.' The journal purported to chronicle 'an out Syrian lesbian's thoughts on life, the universe and so on.'

Well, not so much. After she went missing, people started digging. And it turns out Amina is a 40-year-old white man from Stone Mountain, Georgia named Tom MacMaster.

Christ, what an asshole.

Update: Andy Carvin (@acarvin) of NPR deserves credit for pushing this story from the start, poking at cracks early on, and doing much of the sleuthing that led to the ultimate realization that this was an exploitative hoax. Here's his post at As usual, Andy's doing tireless and important work.


Evolved, 3D printed creatures

Evolved, 3D printed creatures: "

Dolf sez, 'I am growing creatures I call Entoforms using the open source Blender 3D software. To do so, I've written the equivalent of a 300 page book in python scripts, which though a work in progress, are already available. The Entoforms have text as DNA, and can thus be based on words, or names. I print them out in 3D, then pin, and label them in insect boxes like collected invertebrates. These I am selling as limited issue collectible art pieces. To help me create the first larger series, and exhibit them this summer and fall at art galleries... I started a crowdfunding campaign.'


(Thanks, Dolf!)


Remix of The View's "Sextape" episode

[Weird weird weird. -e]
Remix of The View's "Sextape" episode: "

[Video Link] Nick Denboer did a good job of increasing the informational content of The View's 'Sextape' episode. (NSFW)