In an excellent article, Justin Gillis highlights a new paper that shows the West Antarctic Ice sheet to be one of the fastest warming places on Earth.
The black star shows the Byrd Station. The colors show the number of melting days over Antarctica in January 2005. This number increases with warming temperatures (image from supplementary material in Bromwich et al., 2012).
Note to math students: The scientists use linear regression to get the rate of temperature increase.
The record reveals a linear increase in annual temperature between 1958 and 2010 by 2.4±1.2 °C, establishing central West Antarctica as one of the fastest-warming regions globally.
A fascinating study of 56,000 generations of bacteria, in 12 different populations, carefully documents how a new ability evolved in one of the populations — the ability to use citrate for food in addition to glucose.
About the key step in the process:
“It wasn’t a typical mutation at all, where just one base-pair, one letter, in the genome is changed,” he said. “Instead, part of the genome was copied so that two chunks of DNA were stitched together in a new way. One chunk encoded a protein to get citrate [for food] into the cell, and the other chunk caused that protein to be expressed.”
The first stage was potentiation, when the E. coli accumulated at least two mutations that set the stage for later events. The second step, actualization, is when the bacteria first began eating citrate, but only just barely nibbling at it. The final stage, refinement, involved mutations that greatly improved the initially weak function. This allowed the citrate eaters to wolf down their new food source and to become dominant in the population.
Note
I’ve been discussing different genres of scientific writing with my middle school class, so it’s interesting to point out that the article this post refers to is just a press release about the actual research paper. These are two very distinct types of scientific writing.
The rate of radioactive decay of Chlorine-36 (blue x's) seems to be related to the distance between the Earth and the Sun (red line). (Image from Dekant, 2012).
In pre-Calculus, we’re figuring out how to match curves to data. The scientists in this study do something similar, trying to see what types of sinusoidal curves will match the data, then seeing what natural phenomena have the same period (the time it takes for one cycle).
It has always strained credibility that the 98% of our DNA not used to code proteins would be useless. But this non-coding DNA picked up the name “junk DNA” because no-one quite knew what it did. In fact, one study (Nóbrega, 2004) found that deleting large chunks of DNA had no discernible effect on mice; the mice born without these pieces of non-coding DNA were viable.
However, a slew of papers from the Encode project indicate that the part of our genome formerly known as junk DNA, regulates the 2% that does the protein coding:
The researchers … have identified more than 10,000 new “genes” that code for components that control how the more familiar protein-coding genes work. Up to 18% of our DNA sequence is involved in regulating the less than 2% of the DNA that codes for proteins. In total, Encode scientists say, about 80% of the DNA sequence can be assigned some sort of biochemical function.
The appendix has long been supposed to be a vestigial, useless organ. But a 2007 study suggests that it might have had — and may still have in many developing countries — an important role in digestion. It may provide a refuge for helpful, commensal bacteria to repopulate our guts after we purge when we get sick (Bollinger et al., 2007):
The organs of the lower digestive system. The appendix is located in the lower left, near where the small and large intestines meet. Image from Wikipedia.
… the human appendix is well suited as a “safe house” for commensal bacteria, providing support for bacterial growth and potentially facilitating re-inoculation of the colon in the event that the contents of the intestinal tract are purged following exposure to a pathogen.
The shape of the appendix is perfectly suited as a sanctuary for bacteria: Its narrow opening prevents an influx of the intestinal contents, and it’s situated inaccessibly outside the main flow of the fecal stream.
Crude oil is extracted from layers of sand that can be deep beneath the land surface, but it was not created there. Oil comes from organic material, dead plants and animals, that sink to the bottom of the ocean or large lakes. Since organic material is not very dense, it only reaches the bottom of ocean in calm places where there are not a lot of currents or waves that can mix it back into the water. In these calm places, other very small particles like clay can also settle down.
Figure 1. Formation of sandstone (reservoir) and shale (source bed).
Over time, millions of years, this material gets buried beneath other sediments, compressing it and heating it up. Together the organic material and the clay form a type of sedimentary rock called shale. As the shale gets buried deeper and deeper and it gets hotter and hotter, and the organic matter gets cooked which causes it to release the chemical we know as natural gas (methane) and the mixture of organic chemicals we call crude oil (see the formation of oil and natural gas).
Figure 2. The trapping of oil and natural gas by a fault.
Shale beds tend to be pretty tightly packed, and they slowly release the oil and natural gas into the layers of sediment around them. If these layers are made of sandstone, where there is much more space for fluids to move between the grains of sand, the hydrocarbons will flow along the beds until they are trapped (Figure 2).
In this exercise, we will use the wave tank to simulate the formation of the geologic layers that produce oil.
Materials
Wave tank
Play sand (10x 20kg bags)
Colored sand (2 bags)
Observations
For your observations, you will sketch what happens to the delta in the tank every time something significant changes.
Procedure
Fill the upper half of the tank with sand leaving the lower half empty.
Fill the empty part with water until it starts to overflow at the lower outlet.
Move the hose to the higher end so that it creates a stream and washes sand down to the bottom end — observe the formation of the delta.
Observe how the delta builds out (progrades) into the water.
After about 10 minutes dump the colored sand into the stream and let it be transported onto the delta.
After most of the colored sand has been transported, raise the outlet so that the water level in the tank rises to the higher level. — Note how the delta forms at a new place.
After about 10 more minutes dump another set of colored sand and allow it to be deposited on the delta.
Now lower the outlet to the original, low level and observe what happens.
After about 10 minutes, turn off the hose and drain all of the water from the tank.
When the tank is dry, use the shovel to excavate a trench down the middle of the sand tank to expose the cross-section of the delta.
Analysis
1. How did changing the water level affect the formation of the delta.
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2. When you excavated the trench, did you observe the layers of different colored sand in the delta? Draw a diagram showing what you observed. Describe what you observed here.
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3. Was this a realistic simulation of the way oil reservoirs are formed. Please describe all of the things you think are accurate, and all of the things you think are not realistic?
It skims over pyrolysis; chemiluminescence, where the chemical reaction (combustion/oxidation) produces excited atoms and molecules that need spit out (emit) blue light to get to their ground state); and the incandescent light emission of microscopic soot particles which produce the yellow parts of the flame.
I’m not sure who the guy chained to the rock is. It might be Prometheus, who stole fire from the gods, but I don’t remember him being sent into hell in the myth.
Shadow of the planet Venus during it's transit of the Sun on June 5th, 2012 at approximately 18:00 Central Time. Photograph taken from the MH Solar Observatory in St. Louis, MO, USA.
It’s pretty amazing how ecstatic seeing a simple circle with a little blobby dot can make a person feel. Following Ron Hipschman’s instructions, I installed a small aperture (~0.5 mm) solar projector at the newly established Muddle Home Solar Observatory (MHSO). The kids and I used it, and SunAeon’s app, to observe Venus transiting the Sun. It was, in a word, awesome.
The MHSO's small aperture (pinhole), solar projector.
For us the transit occurred late in the day, so by the end we had trees getting in the way.
Trees beginning to obscure the Sun.
If it seems odd that the trees are at the top of the image, it’s because the images in pinhole projectors are inverted. If I flip it around the right way, the image would actually look like this.
Corrected (inverted) image from the pinhole projector.
