Goat Webs?

May 31, 2010

The silk produced by spiders to make their webs has some fairly special structural properties.  It is quite strong, similar in tensile strength to nylon, but is much more elastic (it can be stretched more without breaking or deforming).  It has been used for certain limited applications: for example, to make cross-hairs for optical instruments, and is potentially useful in many other applications:

For instance, due to its strength and elasticity, spider silk fiber could have several medical uses, such as for making artificial ligaments and tendons, for eye sutures, and for jaw repair. The silk could also have applications in bulletproof vests and improved car airbags.

Its wider use, though,  has been limited by the difficulty of obtaining it in quantity.   Spider “farming” has been tried, but spiders are territorial, and the experimental participants tend to end up eating each other.

Now, according to an article at PhysOrg.com, a group of scientists at the University of Wyoming has developed a method for inserting the spider genes that control silk production into goats.   Some of the resulting goat offspring will then produce the protein that makes up spider silk in their milk.  The protein can then be extracted from the goats’ milk, and purified into relatively large quantities of silk.  So far, the goats do not seem to suffer any adverse consequences from the genetic tinkering.  The work is described in more detail in an article at the National Science Foundation Web site.

The research group is now exploring the possibility of putting the silk gene into alfalfa plants.  Alfalfa is a widely-planted crop, which is less unruly and malodorous than goats.   It also has a relatively high protein content, so the potential yield of the silk protein might be quite large.

Sticky Mortar

May 30, 2010

One of the things that makes many monuments from the ancient world, from the Pyramids, to Stonehenge, to the Great Wall of China, so fascinating is that they were accomplished with so little in the way of technology.  One of the minor mysteries of Chinese construction has been how the builders managed to produce a very strong mortar to hold masonry structures together — structures that in many cases have withstood strong earthquakes and modern bulldozers.

According to an article at the PhysOrg.com Web site, scientists have discovered that the secret ingredient comes from sticky rice, a staple food in much of Asian cuisine.   In a paper [abstract] published in the American Chemical Society’s Accounts of Chemical Research, a group of Chinese researchers showed that the mixing of the standard mortar material, slaked lime, with sticky rice soup produced the extra-strong mortar.  The key ingredient in the rice is amylopectin, one of the two key components of starch.  Amylopectin is a polysaccharide, a highly-branched sugar polymer that typically contains 2,000 – 200,000 glucose units.  Sticky rice contains it in abundance; other foods, like waxy corn and waxy potatoes, also contain large amounts.

The addition of amylopectin to the calcium carbonate from the slaked lime results in an organic / inorganic composite material that has exceptional properties, apparently because the amylopectin causes the calcium carbonate to crystallize in a more compact and orderly way:

…  we found that amylopectin in the mortar acted as an inhibitor: The growth of the calcium carbonate crystal was controlled, and a compact microstructure was produced, which should be the cause of the good performance of this kind of organic-organic mortar

The researchers also concluded that using the same mixture was the best mortar to be used in restoring old structures.

And here you thought that rice was just important in Chinese cooking!

GPS to be Upgraded

May 29, 2010

The Global Positioning System [GPS], established beginning in 1973 by the US Department of Defense, has evolved from its secretive beginnings to something close to a household name.  The system is still used for military applications, of course, but it has a much wider customer base.  It is used in mobile phones, so they can be located by emergency services; in navigation devices for vehicles; and for many applications that rely on accurate time measurements.  (Part of the GPS signal is a time stamp from the atomic clock on board the satellite.)

Now, according to an article at the PhysOrg.com site,  the GPS is to receive a significant upgrade, at an estimated cost of $8 billion.   The existing system uses a “constellation” of 24 satellites in orbit around the Earth at an altitude of about 20,200 km; the orbits are arranged so that there are always six satellites above the horizon.  The GPS receiver calculates its position based on the signals from several satellites that it can “see”, and from the time information in those signals.  (In order for the calculation to be accurate enough, adjustments must be included for the effects of General Relativity.)  Current civilian GPS receivers can give horizontal position information accurate within about a five meter radius.

The new system upgrade involves the construction of 30 new satellites, to allow for six spares, by Boeing and Lockheed-Martin.  These satellites will have more available commercial signals, and more accurate atomic clocks, which should have the effect of reducing the error radius to less than two meters.  The upgrade

… will also make the system faster, and there will be provision to prevent disruptions such as accidental jamming of GPS, which in the recent past have caused disruption to emergency services and mobile phone services, as well as causing power outages.

The upgrade is expected to take about ten years to complete.

Happy Birthday, COBOL

May 28, 2010

As an article at the Wired site reminds us, it was 51 years ago today that a meeting at the US Defense Department generated the initial impetus to the development of COBOL (an acronym for COmmon Business-Oriented Language), one of the first high-level computer programming languages (along with FORTRAN).   As its name implies, COBOL’s focus was to be on business data processing, just as FORTRAN was originally intended for scientific and engineering problems.  In both cases, the initial developers of the languages attempted to use syntax that would be familiar to the intended audience.  FORTRAN used a pseudo-mathematical notation (I am ignoring the issue of data types for the moment):


COBOL might have represented the same computation as:


As this example might suggest, COBOL was a very “chatty”, not to say verbose, language.  One of the initial design ideas was that having programs written in a language that, at least superficially, resembled English would lead to clearer programs that could be read by non-technical users and managers.  This was a nice idea that, as far as I know, never amounted to much; it is hard enough to get non-technical people to read documentation that is written in actual English.  And I think most programmers would agree that, except in the initial learning stages, most significant errors are semantic, not syntactical.

Nonetheless, the introduction of COBOL and FORTRAN really was an enormous step forward for the craft of software development; the two languages shared the common idea that a program could be represented in a form that was independent of the particular machine on which it would be run.  They represented early steps toward the idea of standardized computing, an idea that IBM developed with the introduction of the System/360 series of compatible computers in 1964, and one that is a commonplace today.

One of the early champions of the COBOL project was Grace Hopper, an officer in the US Naval Reserve, who was a Vassar graduate with a degree in math and physics, and subsequently a PhD in math from Yale.  She was on the faculty at Vassar until 1943, when she obtained a leave of absence to enlist in the US Navy Reserve.  She worked with many of the pioneers in computing, including work with Howard Aiken at Harvard on the Mark I computer.   According to a story which may be apocryphal, she also coined the term “debugging” after a particular computer problem was found to be due to a moth squashed inside a relay.  I also feel reasonably sure that she is the only female Naval officer to have retired three times, in 1966, 1971, and 1986, the last time as a Rear Admiral.

The original COBOL language was criticized — not without reason — as being too wordy and as encouraging the development of wildly unstructured programs.  Edsger Dijkstra, structured programming advocate and author of the seminal paper, A Case Against the GOTO Statement, was not a big fan of COBOL:

The use of COBOL cripples the mind; its teaching should, therefore, be regarded as a criminal offense.

A number of attempts have been made to introduce more structured language constructs into COBOL, but none of them has been notably successful.  Still, an awful lot of the world has been run on COBOL; although it may now miss the mark in terms of details, its development was an important milestone in the development of computing.

Don’t Touch Those Maps!

May 28, 2010

From time to time, various state legislatures make a bid to see who can pass the most ridiculous law.  (For many years, the Indiana legislature has had a strong competitive position, with its attempt in 1897 to set the value of pi [π] by legislation.)   Now, according to a report on the Nola.com Web site of the New Orleans Times–Picayune, the Louisiana  state legislature has made its own bid for fame in this area.

It seems that the House of Representatives in the Louisiana legislature unanimously [!] approved a bill submitted by State Senator Robert Adley.  The effect of the bill is to increase prison sentences for crimes committed with the use of a “virtual map”.

Adley’s bill defines a “virtual street-level map” as one that is available on the Internet and can generate the location or picture of a home or building by entering the address of the structure or an individual’s name on a website.

This would seem to include all of the usual suspects, such as MapQuest, Google Maps, and so on.  The bill would require that anyone convicted of a burglary who used a virtual map have at least one year added to his/her sentence.  Anyone convicted of an “act of terrorism” (whatever that is) would have a minimum of ten years added to the sentence.

Sometimes, with proposals that don’t make much overall sense, one can discern a sort of weird logic in the background.  In this case, I am at a loss to imagine even a crazy reason for this idea.   And, honestly, under the circumstances, I would think that the Louisiana legislature has more important issues to consider.

Google Releases Chrome 5

May 25, 2010

Google today announced the release of version 5 of its Chrome Web browser.  This version is the first for which stable stage releases have been made for Mac OS X and Linux, as well as for Windows.  (I have been using the Linux beta of Chrome 5 since it was made available roughly a month ago, and have been quite pleased with its speed and overall performance.  I don’t think it is yet quite as stable in use as Firefox, but Google has made impressive improvements since the early versions.)

The new version incorporates a number of HTML 5 compliance features, as well as more capabilities for synchronizing bookmarks and browser preferences across multiple computers.  This version also includes the Adobe Flash plugin by default, although the complete Flash integration that Google has promised is still being tested.  Google also claims that JavaScript execution has been speeded

Users of existing Chrome versions should have the update offered via the built-in update mechanisms.  Otherwise, you can download the new version here.

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