Scientists Use a CT Scanner to Give Whales a Hearing Test

Ted Cranford
Ted Cranford

It's hard to study how whales hear. You can't just give the largest animals in the world a standard hearing test. But it's important to know, because noise pollution is a huge problem underwater. Loud sounds generated by human activity like shipping and drilling now permeate the ocean, subjecting animals like whales and dolphins to an unnatural din that interferes with their ability to sense and communicate.

New research presented at the 2018 Experimental Biology meeting in San Diego, California suggests that the answer lies in a CT scanner designed to image rockets. Scientists in San Diego recently used a CT scanner to scan an entire minke whale, allowing them to model how it and other whales hear.

Many whales rely on their hearing more than any other sense. Whales use sonar to detect the environment around them. Sound travels fast underwater and can carry across long distances, and it allows whales to sense both predators and potential prey over the vast territories these animals inhabit. It’s key to communicating with other whales, too.

A CT scan of two halves of a dead whale
Ted Cranford, San Diego State University

Human technology, meanwhile, has made the ocean a noisy place. The propellers and engines of commercial ships create chronic, low-frequency noise that’s within the hearing range of many marine species, including baleen whales like the minke. The oil and gas industry is a major contributor, not only because of offshore drilling, but due to seismic testing for potential drilling sites, which involves blasting air at the ocean floor and measuring the (loud) sound that comes back. Military sonar operations can also have a profound impact; so much so that several years ago, environmental groups filed lawsuits against the U.S. Navy over its sonar testing off the coasts of California and Hawaii. (The environmentalists won, but the new rules may not be much better.)

Using the CT scans and computer modeling, San Diego State University biologist Ted Cranford predicted the ranges of audible sounds for the fin whale and the minke. To do so, he and his team scanned the body of an 11-foot-long minke whale calf (euthanized after being stranded on a Maryland beach in 2012 and preserved) with a CT scanner built to detect flaws in solid-fuel rocket engines. Cranford and his colleague Peter Krysl had previously used the same technique to scan the heads of a Cuvier’s beaked whale and a sperm whale to generate computer simulations of their auditory systems [PDF].

To save time scanning the minke calf, Cranford and the team ended up cutting the whale in half and scanning both parts. Then they digitally reconstructed it for the purposes of the model.

The scans, which assessed tissue density and elasticity, helped them visualize how sound waves vibrate through the skull and soft tissue of a whale’s head. According to models created with that data, minke whales’ hearing is sensitive to a larger range of sound frequencies than previously thought. The whales are sensitive to higher frequencies beyond those of each other’s vocalizations, leading the researchers to believe that they may be trying to hear the higher-frequency sounds of orcas, one of their main predators. (Toothed whales and dolphins communicate at higher frequencies than baleen whales do.)

Knowing the exact frequencies whales can hear is an important part of figuring out just how much human-created noise pollution affects them. By some estimates, according to Cranford, the low-frequency noise underwater created by human activity has doubled every 10 years for the past half-century. "Understanding how various marine vertebrates receive and process low-frequency sound is crucial for assessing the potential impacts" of that noise, he said in a press statement.

Periodic Table Discovered at Scotland's St Andrews University Could Be World's Oldest

Alan Aitken
Alan Aitken

The oldest surviving periodic table of elements in the world may have been found at the University of St Andrews in Scotland, according to the Scottish newspaper The Courier.

University researchers and international experts recently determined that the chart, which was rediscovered in a chemistry department storage area in 2014, dates back to 1885—just 16 years after Russian chemist Dmitri Mendeleev invented the method of sorting the elements into related groups and arranging them by increasing atomic weight.

Mendeleev’s original periodic table had 60 elements, while the modern version we use today contains 118 elements. The chart found at St Andrews is similar to Mendeleev’s second version of the table, created in 1871. It’s thought to be the only surviving table of its kind in Europe.

The periodic table soaks in a washing treatment
Richard Hawkes

The St Andrews table is written in German, and was presumably produced for German universities to use as a teaching aid, according to St Andrews chemistry professor David O’Hagan. The item itself was dated 1885, but St Andrews researcher M. Pilar Gil found a receipt showing that the university purchased the table from a German catalog in 1888. A St Andrews chemistry professor at the time likely ordered it because he wanted to have the latest teaching materials in the scientific field, even if they weren't written in English.

When university staffers first found the table in 2014, it was in “bad condition,” O’Hagan tells The Courier in the video below. The material was fragile and bits of it flaked off when it was handled. Conservators in the university's special collections department have since worked to preserve the document for posterity.

The 19th century table looks quite a bit different from its modern counterparts. Although Mendeleev laid the groundwork for the periodic table we know today, English physicist Henry Moseley improved it in 1913 by rearranging the elements by the number of protons they had rather than their atomic weight. Then, in the 1920s, Horace Deming created the boxy layout we now associate with periodic tables.

Learn more about the St Andrews discovery in the video below.

[h/t The Courier]

Can You Tell an Author’s Identity By Looking at Punctuation Alone? A Study Just Found Out.

iStock.com/RyersonClark
iStock.com/RyersonClark

In 2016, neuroscientist Adam J Calhoun wondered what his favorite books would look like if he removed the words and left nothing but the punctuation. The result was a stunning—and surprisingly beautiful—visual stream of commas, question marks, semicolons, em-dashes, and periods.

Recently, Calhoun’s inquiry piqued the interest of researchers in the United Kingdom, who wondered if it was possible to identify an author from his or her punctuation alone.

For decades, linguists have been able to use the quirks of written texts to pinpoint the author. The process, called stylometric analysis or stylometry, has dozens of legal and academic applications, helping researchers authenticate anonymous works of literature and even nab criminals like the Unabomber. But it usually focuses on an author's word choices and grammar or the length of his or her sentences. Until now, punctuation has been largely ignored.

But according to a recent paper led by Alexandra N. M. Darmon of the Oxford Centre for Industrial and Applied Mathematics, an author’s use of punctuation can be extremely revealing. Darmon’s team assembled nearly 15,000 documents from 651 different authors and “de-worded” each text. “Is it possible to distinguish literary genres based on their punctuation sequences?” the researchers asked. “Do the punctuation styles of authors evolve over time?”

Apparently, yes. The researchers crafted mathematical formulas that could identify individual authors with 72 percent accuracy. Their ability to detect a specific genre—from horror to philosophy to detective fiction—was accurate more than half the time, clocking in at a 65 percent success rate.

The results, published on the preprint server SocArXiv, also revealed how punctuation style has evolved. The researchers found that “the use of quotation marks and periods has increased over time (at least in our [sample]) but that the use of commas has decreased over time. Less noticeably, the use of semicolons has also decreased over time.”

You probably don’t need to develop a powerful algorithm to figure that last bit out—you just have to crack open something by Dickens.

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