Author: Lensyl Urbano

Pollution and Crime: Leaded Gasoline and Murder

The startling correlation between the amount of lead pollution and the murder rate 21 years later. Graph from Nevin (2012).

Rick Nevin‘s research provides a lot of evidence that the amount of violent crime — murders, aggravated assault, etc. — are the result of lead pollution. Lead was added to gasoline until the 1970’s. When the gasoline was burned in car engines, the lead was released into the atmosphere where it could get into people’s systems just by breathing.

Quite a number of studies taken together have shown that high blood lead levels result in lower IQ’s, which, in turn, seems to increase aggressive behavior.

Long-term trends in paint and gasoline lead exposure are also strongly associated with subsequent trends in murder rates going back to 1900. The findings on violent crime and unwed pregnancy are consistent with published data describing the relationship between IQ and social behavior. The findings with respect to violent crime are also consistent with studies indicating that children with higher bone lead tend to display more aggressive and delinquent behavior.

— Nevin (2000): How Lead Exposure Relates to Temporal Changes in IQ, Violent Crime, and Unwed Pregnancy (pdf pre-print) in Environmental Research.

Kevin Drum summarizes the research and goes into the details to disprove the other theories for peaks in crime rates in the last century.

↬ The Dish

Learning the Periodic Table: A Prototype

My middle school class is about to cover some very basic chemistry so I’ve asked them to memorize the first 20 elements in their correct order on the periodic table. To help, I’ve put together this interactive exercise where they drag an icon of the element to its correct place on the table. It says the name of the element whenever you start dragging a tile with the symbol. It’s also timed so students can quantify and compare how good they are.

Prototype exercise for learning the first 20 elements of the periodic table.

In this first prototype the elements are presented in order, but I figure that additional levels could have:

  • The elements come up at random (done).
  • Have the elements come up by vertical column (group) (done).
  • Instead of tiles with the elements, have diagrams with their electron configuration.
  • The program say the name of the element and the student has to click on the right cell in the table.

This was put together using HTML5 and Javascript. KineticJS was particularly useful. It should, in theory, work in any browser (but I have only tested it in Firefox and Google Chrome) and on touch-screen tablets as well.

Gardens Reduce Violence

A fascinating article on the relationship between environmental conditions and sociology, explains how urban community gardens — in formerly vacant lots — actually reduced violence in the areas around them.

There’s been a growing body of research that suggests that urban farming and greening not only strengthen community bonds but also reduce violence. …

Over the course of 10 years, [gradens] reduced shootings in the areas surrounding these renewed lots. Part of it was practical: The vacant lots had previously been hiding places for guns. … and … “People just became more in touch with their neighbors. People felt more connected to each other.”

— Kotlowitz and Schiffer (2012): Plant Tomatoes. Harvest Lower Crime Rates in Mother Jones.

The Science of Champagne Bubbles

This nice little video combines a bit of physics, chemistry, and biology as it discusses how bubbles form in champagne: the gas is carbon dioxide; carbon dioxide forms from the fermentation of sugars by yeast — it’s a byproduct of the reaction that produces alcohol; the bubbles form at tiny flaws or bubbles in the glass (so you can put in tiny flaws to control where the bubbles form); the bubbles rise because the gas is less dense than the liquid around it; and the bubbles expand as they rise because the pressure of the liquid becomes less and less the closer to the surface you are.

↬ The Dish

Fish Genes in Tomatoes

PBS has a nice list of genetic modifications to four different plants. First on the list is the antifreeze gene from a fish that was inserted into a tomato. The tomato was infected with a bacteria that had the gene in a genetically engineered plasmid. The PBS site also discusses Bt Corn, which produces it’s own pesticide, Golden Rice, which produces it’s own beta-carotene, and the herbicide resistant Roundup Ready Soybeans.

Golden Rice produces beta-carotene, which the body uses to produce Vitamin A. Two genes, one from daffodils and one from a soil bacteria, were inserted into the rice DNA. Image from the International Rice Research Institute (IRRI) via Wikipedia.

Regression with Gnumeric

A test regression (linear equation) using Gnumeric.

Finally, I’ve found a spreadsheet application (Gnumeric) with a reliable Solver for doing regressions. And it’s free. The only tricky part is that there’s no native port for Macs; you have to use a command line package manager to install it (I used Fink).

Gnumeric, however, seems to be an excellent tool for data analysis.

Sending Invasive Species to Mars

George Dvorsky summarizes a new study showing six types of bacteria found in Siberia are able to survive, and even thrive, under Mars-like conditions.

The researchers took these cultures [from Siberian permafrost] and exposed them to similar conditions found on Mars, including a severe lack of oxygen, extreme cold temperatures, and very low pressure (about 150 times lower than the Earth’s, about 7 millibars). The experiment was run over the period of 30 days. Over 10,000 isolates were exposed to these conditions — and they all died.

Except six.

And in fact, these six surviving microbes actually did better under these conditions. Surprised by the result, the researchers took a closer look at the survivors, and following a genetic analysis concluded that they all came from the same genus: an extremely hardy extremophile called Carnobacterium.

— Dvorsky (2012): Scientists show that microbes from Earth can survive conditions found on Mars in io9.

So now we have to wonder if we’ve already, inadvertently, sent life to Mars.