DNA Curves

August 13, 2009

We all know of DNA (deoxyribonucleic acid) as the “double helix” molecule that carries the encoded genetic information of all living things.  We’ve seen it portrayed as a means of identifying people on shows like CSI.  But the remarkable properties of DNA mean that it can be used in other ways, too.

The Technology Review has an article on the use of DNA in nanotechnology.  DNA is useful in this field because it encodes not only the chemical composition of a substance (such as a protein), but also its shape.  (The proper functioning of many biological molecules is intimately related to their shape.)   Previous work has developed a technique called “DNA Origami”  for creating two-dimensional structures, such as lattices.

The new work, carried out by researchers at Harvard University and the Technische Universität München and reported in Science, extends the technique so that three-dimensional objects can be constructed from a DNA “recipe”.

The researchers created objects including nanoscale “gears,” a wireframe beach ball-shaped capsule, and triangles with either concave or convex sides.

(The Technology Review article has some impressive images of some of these structures.)

These laboratory techniques are still a long way from any practical utilization.  But it is very impressive that we have discovered a way to build structures on the same scale as a virus.  The possibilities for their use include drug delivery, truly tiny computing devices, and probably many more that are yet to be thought of.

Hurricane Frequency

August 13, 2009

The BBC News is reporting on a new study of annual hurricane activity, going back over 1,500 years, that has just been published in the journal Nature (press release).  According to the study, which was conducted by a team led my Dr. Michael Mann, of Penn State University, the number of hurricanes that have crossed the shoreline in the last ten years represents a peak comparable to one seen about 1,000 years ago.  Thus, there is evidence to support a natural, long-period cycle in the amount of hurricane activity in the Atlantic.

The study looked at what is called “overwash” – debris from the shore that is picked up by the storm and carried inland, into a lagoon or other body of water.  The sediment deposited can be dated via radio-carbon techniques.  The team also used a computer model to examine its correspondence with the historical data.

The model includes three factors known to be important in determining hurricane formation: sea surface temperature in the tropical Atlantic Ocean, the El Nino/La Nina cycle in the eastern Pacific, and another natural climatic cycle, the North Atlantic Oscillation.

Unfortunately, the interplay of these factors is not completely understood.  But this research should contribute some pieces of the puzzle.


August 13, 2009

Following on to Microsoft’s announcement and promotion of Bing, its new search engine, Google has made available a version of its next-generation search engine, code-named ‘Caffeine’,  for testing.  The Google “Webmaster Central Blog” has an overview of the test environment, and how to give feedback to Google on your results.

This is a test system, so I do not recommend using it routinely or for critical work, but it’s interesting to compare results from the new and existing production search engines.  My very limited experience so far suggests that the Caffeine search produces more up-to-date results; but try iot out for yourself if you’re interested.

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