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A 17-year batch of cicadas is expected to emerge in the greater Chicago area (where I live) this May or early June. Known as Brood XIII, these cicadas are Magicicadas and are periodicals, meaning they emerge to mate and lay eggs only once every 13 or 17 years, depending on the brood. (Annuals, on the other hand, appear every year in smaller numbers.) The last time Brood XIII emerged in Chicago was in 1990, creating a outdoor spectacle I still remember, even though I was only six at the time. This year I'll try to get some pictures to post.

The Lake County Forest Preserves has an informative article about cicadas. The hat tip for that link goes to Cicada Mania, a unique blog tracking everything that has to do with these loud and remarkable bugs.

Below is a painting of Magicicada septendecim from Robert E. Snodgrass's 1930 book, "Insects, Their Ways and Means of Living."

image by R.E. Snodgrass. not in copyright. 

For any of you interested in such things, I've come across an interesting recent article criticizing how the Dead Sea Scrolls are often presented. Apparently the Qumran-Essene theory (the theory that the biblical scrolls were written and deposited by a religious sect called the Essenes) has been accepted and presented without question at certain Scroll exhibitions and press releases. Last August an alternative theory of the Qumran settlement made the news after being published in Biblical Archaeology Review.

The article, by Norman Golb of the University of Chicago, is scholarly and long, but here's the abstract:

This article examines a series of efforts initiated over the past decade by traditional Dead Sea Scrolls scholars in defense of the original Qumran-Essene theory of Scroll origins. These efforts notably include: (1) declarations to the press concerning DNA analyses, the results of which were thereafter never released; (2) unverifiable claims concerning an ostracon found at Qumran, repeated in several publications and never retracted; (3) a series of Scroll exhibits that appear designed to lead the public towards acceptance of the Qumran-Essene theory as factually correct; and (4) a recently organized press campaign also appearing to encourage the public, on the basis of parasitological organisms found near Khirbet Qumran, to acquiesce in the truth of that theory. The author argues that the totality of these efforts raises serious concerns regarding the treatment of archaeological and manuscript discoveries and their public presentation.

 The link(pdf).

I haven't read it, so if anyone takes the time to do so please drop a comment and tell me what you think.

I was perusing an issue of NewScientist (an old one--from January 20-26 of this year) and found a fascinating article about accelerated gold formation. The article link is here, but unfortunately you can't view most of it without a subscription. (Notice I shamelessly stole their title for use on this post.) Luckily, there's another article on the same subject here, published in the Geotimes.

In the article science journalist Phil McKenna explores how theories of slow gold formation have been turned on their head in light of recent empirical evidence that gold can form quickly. At the center of interest is the Lihir gold mine on Papua New Guinea's Lihir Island, where lies a gold deposit containing around 1600 metric tons of the lovely stuff. The mine is unique not only for the large size of its deposit but for the ongoing volcanic activity in the region. Hydrothermal activity is continuous at the mine, and several miles south of the island there are seafloor vents containing the world's highest underwater gold concentration rate.

 It turns out that the Lihir deposit is still being formed as you read this. Kevin Brown, a geochemist from a New Zealand research center, knew gold deposits could form from the heated water in hydrothermal vents. As the water turned into steam, minerals--including gold, if the geologic location was right--were left behind as a deposit. He decided to conduct a test at Lihir to see if the deposits there might have been formed in this way. Sure enough.

 It turns out that at the current rate of hydrothermal activity, 24 new kilograms of gold are accruing to the Liher deposit every year. At that rate, says Brown and his colleague, Stuart Simmons, the entire deposit could have formed in 55,000 years. Their findings were published in Science last year.

Christoph Heinrich, a Zurich researcher who has discovered very high concentrations of gold trapped in quartz crystals, thinks the deposit at Lihir could have formed even faster:

 [Heinrich] thinks the hydrothermal system investigated by Brown and Simmons may have passed its prime and could once have contained greater concentrations of gold. "We have found fluids that had a thousand times higher concentrations," Heinrich says of sites he has studied in Argentina, Indonesia, south-east Europe and the US. "If you spin the same argument that they are using with a thousand times higher concentrations, then the time it takes might have been a thousand times shorter--50 or 60 years."   --NewScientist

 All this to say that, surprise, gold can form quickly. Please be aware that not all geologists are happy about this prospect, particularly when it conflicts with other favored gold deposition theories. Says Stuart Simmons, "Geologists hate each other for life over their opinions on this stuff. These are highly emotive debates that take on an almost religious fervor."

In case you were wondering, Simmons and Brown have already tried designing a gold trap. (Were you hoping you had thought of it first?) Unfortunately, the cost of collecting the gold would appear to outweigh the metal's value. Harvesting deposits from hydrothermal vents would probably have to be incorporated into existing hydrothermal plants in order to be cost effective. Simmons and Brown are still working on that one.

Image copyright: Silvia Silva. Used by permission.

A nice new satellite pic (actually a composite of images from NASA's Landsat) from the Earth Observatory.  The volcano, Tarso Toussidé, is located on Chad's Tibesti Mountain Range.  From the EO's site:

Looking like the result of a giant inkwell tipped on its side, Tarso Toussidé underwent a violent eruption in the recent geologic past, and the remains of that eruption have stained the ground black. The volcano ejected tephra, fragments of rock and volcanic glass, lava, and ash. Tephra does not last on the landscape as long as consolidated volcanic rocks such as tuff or lava, so the presence of tephra suggests fairly recent activity. In the middle of the field of dark tephra is Pic Toussidé, a lava dome poking out of the current caldera.

Volcanoes often sport multiple calderas, particularly as the primary site for eruptive activity shifts over time. East of Pic Topussidé are two calderas, the southern one bearing a white splotch roughly 2 kilometers long. This white color could result from salt. Water pooling in the caldera would not have an outlet, and as the water evaporated, minerals such as salt would be left behind.

Image courtesy Robert Simmon/Earth Observatory.

Also: NASA released some cool movies today of Saturn revolving in orbit with its moons. They're sharp enough to look like computer animation but are really compilations of images taken by Hubble over periods of several hours.

Surrounding the beautiful planet we call home, a powerful but invisible shield acts as a barrier to protect us from the sun.  The magnetosphere, reaching 40,000 miles beyond the earth on the sunward side, blocks high levels of solar particles that would otherwise harm life.

The Earth's magnetic field is formed by the rotation of molten iron in the core.  The movement of the iron works like a power plant dynamo, building an electrical current and producing a local electromagnetic field--only in this case the dynamo is planet-sized. The field turns the earth into a giant magnet, with north and south poles.

However, in the 1960's, scientists testing the magnetism of igneous rocks along the Mid-Atlantic Ridge found that the polarity of the rocks frequently reversed--an indication that the earth's magnetic poles have reversed several times in the past.  The question was, why?

Well, our knowledge of the earth's inner currents is still too sketchy to offer a complete answer. But scientists in recent years have come up with some cool ways of testing the relationship between the earth's core and magnetosphere.  In 1999, for example, a team of researchers in Latvia demonstrated that spinning a cylinder of liquid sodium produced a magnetic field, although in their field the poles did not change.

Last week news broke of another experiment using a cylinder full of sodium.  Michaël Berhanu and his Parisian team of scientists created an earth core simulation by rotating two disks--the ends of the cylinder containing the molten metal--in opposite directions.  By adjusting the speeds of the disks, they figured out how to induce the magnetic poles to flip.

When the disks were spun at equal but opposite rates, this field stayed constant. But if the rotation rates were different, the behaviour was more complex . . .

 Under these conditions the magnetic field switches polarity apparently at random, typically every minute or so. It happens just as it happens to the Earth, with the field declining slowly to zero and then reappearing quickly in the opposite orientation. They find that one field orientation persists more often than the other, presumably because of a bias introduced by the Earth's magnetic field.

  The reversals seem to happen when the energy needed to spin the driving disks — which varies because the turbulence of the liquid produces a variable amount of friction — is lower than average.  -Nature

Although many theories of polar reversal point to movement in the mantle as a trigger, Berhanu's group believes that all the ingredients needed for reversal are contained in the core.  As far as I can tell though, the experiment does not rule out the possibility of external influences.

*To give credit where credit is due, I must add that my uncle, Martin Devine, a science teacher currently teaching anatomy at Indiana University, thought of this "spinning cylinder" experiment idea all by himself one day a couple months ago, when he and I were discussing the problem of polar reversal over lunch. His idea, though, was to use an actual sphere.  He says that MRI could possibly be used to map the current patterns as they spin inside. Oh the things we could do if we had the time and money. . .

(ScienceDaily coverage) 

Image credit: NASA Marshall Space Flight Center (NASA-MSFC)

The New York Times has published an article spotlighting critics--scientists, let's be clear--who don't agree with all the claims made in Al Gore's documentary "An Inconvenient Truth."  While some say that notwithstanding minor debatable points, Gore was accurate "in terms of the big picture," others have come out of the closet to challenge the "alarmism" contained in Gore's gospel.

“Nowhere does Mr. Gore tell his audience that all of the phenomena that he describes fall within the natural range of environmental change on our planet,” Robert M. Carter, a marine geologist at James Cook University in Australia, said in a September blog. “Nor does he present any evidence that climate during the 20th century departed discernibly from its historical pattern of constant change.”

In October, Dr. Easterbrook made similar points at the geological society meeting in Philadelphia. He hotly disputed Mr. Gore’s claim that “our civilization has never experienced any environmental shift remotely similar to this” threatened change.

Nonsense, Dr. Easterbrook told the crowded session. He flashed a slide that showed temperature trends for the past 15,000 years. It highlighted 10 large swings, including the medieval warm period. These shifts, he said, were up to “20 times greater than the warming in the past century.”

Getting personal, he mocked Mr. Gore’s assertion that scientists agreed on global warming except those industry had corrupted. “I’ve never been paid a nickel by an oil company,” Dr. Easterbrook told the group. “And I’m not a Republican.”

 Benny J. Peiser, an anthropologist in the UK who edits a climate change newsletter, told the Times "Hardly a week goes by without a new research paper that questions part or even some basics of climate change theory."

Yesterday the BBC reported on a global project to compile the world's scientific knowledge of rocks, and make the info accessible from a single online portal.  The OneGeology project, as it's being called, is being spearheaded by the British Geological Survey, and aims to make earth surface rock data available at a scale of 1:1,000,000.

The project, which has the backing of Unesco and five other global umbrella bodies, will be a centrepiece of the International Year of Planet Earth in 2008.

Scientists would expect to have the first release of their portal up and running by then. It will present the information with the use of a "virtual globe", in much the same way as Google Earth now presents satellite images.

 Google Earth became a useful tool for archaeologists, who were able to see faint discolorations in surface vegetation above unknown, buried structures. The OneGeology project promises surprises of its own. Whenever information is made freely available to people, scientists among them, new theories take form and old riddles find answers. I envision the OneGeology project becoming a major resource for new geologic models like flood geology. --Speaking of which, in July Cedarville University will be hosting a geology conference that will focus on (my favorite) young earth creation geology.

In Astronomy: A Max Planck Institute report says scientists have physically detected a tiny speed increase in the rotation rate of an asteroid. They say the acceleration is due to the heat from sunlight--an effect called YORP theory (here's a mouthfull: Yarkovsky-O’Keefe-Radzievskii-Paddack effect), which had been predicted but never observed. You can view a 7 Meg QuickTime movie of the asteroid in question hurtling through space here.  (An idea similar to this was supposed to propel the private Cosmos 1 spacecraft to high speeds, except in that case I believe it was light pressure, not heat, that was expected to energize the craft.  Cosmos 1 was lost during launch in 2005.)

A study that will probably turn out to be controversial claims that mice can think about what they know or don't know, and make decisions accordingly. Read the evidence for yourself.  Could this explain those occasional mice who never seem to get caught in mousetraps?  "What are we going to do tomorrow night, Brain?" (Sorry.)

Even more controversial may be a neural theory proposed by Copenhagen University scientists who argue sound waves, not electric signals, are the driving force of nerve impulses. From CBC News:

The Copenhagen University researchers argue that biology and medical textbooks that say nerves relay electrical impulses from the brain to the rest of the body are incorrect.

"For us as physicists, this cannot be the explanation," said Thomas Heimburg, an associate professor at the university's Niels Bohr Institute. "The physical laws of thermodynamics tell us that electrical impulses must produce heat as they travel along the nerve, but experiments find that no such heat is produced."

. . .  

Heimburg and [Copenhagen University's Andrew] Jackson theorize that sound propagation is a much more likely explanation. Although sound waves usually weaken as they spread out, a medium with the right physical properties could create a special kind of sound pulse or "soliton" that can propagate without spreading or losing strength.

The physicists say because the nerve membrane is made of a material similar to olive oil that can change from liquid to solid through temperature variations, they can freeze and propagate the solitons.

 Such a theory, if proven to be true, would revolutionize our view of the nervous system.