MI weekly selection #3

Honolulu (Oahu Island) | Credit: Wikimedia Commons

The lifespan of words

A recent analysis has found that as a language grows over time, it becomes more set in its ways. New words are always being added, according to this study, but few become widely used and part of the standard vocabulary.

The scientists found that as the vocabulary of a language grew, a word’s popularity would change less and less, until the modern era where the most popular words have remained constant for decades. It wasn’t just English that “cooled” as it grew. They find this overwhelming trend across all languages studied.

Live Science

Alexander M. Petersen, Joel N. Tenenbaum, Shlomo Havlin, H. Eugene Stanley & Matjaž Perc Languages cool as they expand: Allometric scaling and the decreasing need for new words Scientific Reports 2, Article number: 943 doi:10.1038/srep00943

Motivation and hard work are the clues to excel in mathematics

Just how innate math skills are is a controversial question. Some studies show that math skills emerge in babies, while others show that culture plays a huge role in shaping those skills. For instance, men consistently outperform women on standardized math tests. But those differences may be due to math anxiety, or cultural influences, other studies have shown. And in opinion surveys, people in Eastern countries often rate effort as most important to math ability, while Westerners typically say math ability is inborn.

To find out which factor was more important, researchers tracked about 3,500 children from Bavaria as they completed an IQ test and an assessment of their algebraic and geometric know-how from 5th grade to 10th grade.

They found that the children who improved in math over the years were disproportionately those who said they “agreed” or “strongly agreed” with statements such as, “When doing math, the harder I try, the better I perform,” or “I invest a lot of effort in math, because I am interested in the subject”– even if they had not started out as high-achieving students. In contrast, kids who said they were motivated purely by the desire to get good grades saw no greater improvement over the average. As for study strategies, those who said they tried to forge connections between mathematical ideas typically improved faster than kids who employed more cursory rote-learning techniques.

Time

Murayama, K., Pekrun, R., Lichtenfeld, S. and vom Hofe, R. (2012), Predicting Long-Term Growth in Students’ Mathematics Achievement: The Unique Contributions of Motivation and Cognitive Strategies. Child Development. doi: 10.1111/cdev.12036

Blinking to power down

Discovered less than a decade ago, the default mode network is the brain’s “idle” setting. In times when our attention is not required by a cognitive task such as reading or speaking, this far-flung cluster of brain regions comes alive, and our thoughts wander freely. In idle mode, however, our thoughts seldom stray far from home: We contemplate our feelings; we wonder what a friend meant by a recent comment; we consider something we did last week, or imagine what we’ll do tomorrow. Most of us take between 15 and 20 such moments of downtime per minute, and scientists have observed that most blinking takes place near or at the point of an “implicit stop”: While reading or listening to another person, that generally comes at the end of a sentence; while watching a movie, for instance, we’re most likely to blink when an actor turns to leave the scene or when the camera shifts to follow the dialogue.

When subjects blinked, the researchers detected a momentary stand-down within the brain’s visual cortex and somatosensory cortex – both involved with processing visual stimuli – and in areas that govern attention. The circuitry of the Default Mode Network stepped up to fill the momentary lapse in attention, and then yielded again as order – and attention – was restored.

Medical Express

Tamami Nakanoa, Makoto Katoc,Yusuke Moritoc, Seishi Itoid, Shigeru Kitazawaa, Blink-related momentary activation of the default mode network while viewing videos PNAS December 24, 2012, DOI:10.1073/pnas.1214804110

Optically controlling the motion of levitating graphite

Magnetic levitation has been demonstrated for a variety of objects, from trains to frogs, but so far no one has developed a practical maglev-based actuator that converts some external source of energy into motion. Now in a new study, researchers for the first time have used a laser to control the motion of a magnetically levitating graphite disk. By changing the disk’s temperature, the laser can change the disk’s levitation height and move it in a controlled direction, which has the potential to be scaled up and used as a light-driven human transportation system. Laser light or sunlight can also cause the levitating disk to rotate at over 200 rpm, which could lead to a new type of light energy conversion system. Phys.org

Masayuki Kobayashi and Jiro Abe Optical Motion Control of Maglev Graphite J. Am. Chem. Soc., 2012, 134 (51), pp 20593–20596 DOI:10.1021/ja310365k

Basaltic islands are dissolving from within

The Hawaiian Islands are slowly dissolving. Eventually, Oahu’s Koolau and Waianae mountains will dwindle to little more than a flat, low-lying island like Midway. While erosion is certainly a guilty party, researchers contend that the mountains of Oahu are, in fact, dissolving from within.

Scientists calculated the mass Oahu loses each year. Although one might expect rain to carry away most of the soil in such a wet climate, underground freshwater springs actually removed the bulk of the mineral material from Oahu, the researchers found.

Science Recorder

Stephen T. Nelson, David G. Tingey, Brian Selck, The denudation of ocean islands by ground and surface waters: The effects of climate, soil thickness, and water contact times on Oahu, Hawaii Geochimica et Cosmochimica Acta Volume 103, 15 February 2013, Pages 276–294 DOI 10.1016/j.gca.2012.09.046

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