Shake and Break
Shake something quickly enough or strongly enough and it will break apart. That can happen on a large scale -- earthquakes come to mind -- but it can happen on a microscopic level too. Now, scientists have shown that small-scale shaking and breaking can be used to detect viruses in people.
The researchers, from the University of Cambridge in England, used a crystalline quartz disk as a detector. The crystal has piezoelectric qualities, meaning that it can move if an electric charge is applied and, conversely, can generate an electric charge if moved. In their technique, described in the journal Nature Biotechnology, the disk is coated with antibodies for herpes simplex virus and then exposed to a solution containing the virus. The viral particles, in turn, adhere to the antibodies.
An alternating electric charge is then applied to the disk and steadily increased, making the disk vibrate faster and faster. At some point, the shaking is enough to stretch the bonds between the virus and antibody until they break. When that happens, some of the elastic energy from the stretching of the bonds is converted to sound (think of the noise that occurs when a rubber band is stretched too far and breaks). Some of this sound hits the disk, making it vibrate anew and generating an electric charge that can be measured.
The researchers found that the charge produced was proportional to the concentration of viral particles in the solution, from a million or so per microliter down to about one.
So the technique, when fully developed, should prove useful for detecting even small amounts of virus in humans in a clinical setting. Other virus-detection methods involve amplifying the amount of virus, which requires lab work and introduces the possibility of contamination that may affect the results.Continue reading the main story
Surveying the Coral
There is little doubt that coral reefs around the world are in trouble, stressed and dying because of local problems like overfishing, pollution and sedimentation (from land erosion).
But just how much of the reefs, which exceed 200,000 square miles, is on the critical list has been difficult to determine. Satellite images cannot distinguish between sick and healthy coral, and while a scuba-diving scientist can, such underwater surveys are tedious and time-consuming.
Now, however, scientists in England, Monaco and the United States have devised a method to quickly assess the health of a reef, from the air. Their technique takes advantage of the fact that living and dead coral are slightly different colors.
They researchers, reporting in the journal Nature, used an airplane equipped with a spectrographic camera, one that records the spectral lines of light reflected off the reefs.
The camera, working at an altitude of 3,000 feet, took images in which each square meter of reef was a single pixel, of a uniform color. A computer then analyzed each pixel to determine if it represented living or dead coral or something else, like sand.
The researchers said they were able to survey about 25 acres of reef in about an hour, orders of magnitude faster than underwater survey methods.
Big Cats Get New Reserve
Some of the world's most endangered big cats are getting much-needed protection. China has agreed to establish a reserve in the northeastern part of the country, on the Russian border, to help protect the habitat of Siberian tigers and Far Eastern leopards.
Fewer than 400 Siberian tigers remain in the wild, and the leopard population is below 50. These cats have lost sources of food and have resorted to killing livestock, resulting in reprisal killings. Among other things, the reserve will protect wild prey so the cats will have enough to eat.
The reserve is being established in conjunction with the Wildlife Conservation Society, which will help manage it.Continue reading the main story