Investigadores lograron descifrar el genoma de un homínido primitivo, el hombre de Denisova, y compararlo con el de los hombres de Neanderthal y los seres humanos modernos, usando una muestra de ADN extraída de un hueso que tiene unos 80,000 años.
Uno de nuestros más distantes antepasados, el Ichthyostega, es también uno de los primeros tetrápodos que pisaron tierra.
Hasta hace poco, se creyó que esta criatura reptaba sobre el barro en cuatro patas como una salamandra. Pero las primeras reconstrucciones en 3-D del esqueleto del Ichthyostega indican que su antebrazo no podía rotar y doblarse lo suficiente como para que el animal anduviera en cuatro patas.
Researchers at The University of Texas at Dallas (UTD), led by Dr. Lee Bulla, have demonstrated for the first time the selective cytotoxicity of Bacillus thuringiensis subsp. israelensis Cry4B toxin is mediated by BT-R3.
Imagine if you could just breathe on a little device and it would tell you whether you had asthma or lung cancer. If only you could point a camera to a fish to find out if it’s tainted. Or how about photographing the smoke from a chimney or an exhaust pipe and immediately be able to identify which pollutants are being emitted?
All this could become possible thanks to an invention by three scientists from the Department of Photonics Engineering at the Technical University of Denmark (DTU).
They have invented an extremely sensitive and compact camera accessory, which can capture radiation in the mid-infrared region, and can be used to identify a wide range of chemicals from a distance.
The device operates by detecting the characteristic spectral fingerprints emitted by chemical substances. Gas molecules vibrate in very specific ways. When they do, they absorb or emit an infrared light corresponding to the vibrational mode of the individual molecule. Measuring this light makes it possible to identify the type of gas. The camera can not only measure the radiation from the molecules, it can also reveal when the molecules absorb the radiation.
Our planet's magnetic field is in a constant state of change, say researchers who are beginning to understand how it behaves and why.
Every few years, scientist Larry Newitt of the Geological Survey of Canada goes hunting. He grabs his gloves, parka, a fancy compass, hops on a plane and flies out over the Canadian arctic. Not much stirs among the scattered islands and sea ice, but Newitt's prey is there--always moving, shifting, elusive. His quarry is Earth's north magnetic pole. Scientists have long known that the magnetic pole moves. James Ross located the pole for the first time in 1831 after an exhausting arctic journey during which his ship got stuck in the ice for four years. No one returned until the next century. In 1904, Roald Amundsen found the pole again and discovered that it had moved--at least 50 km since the days of Ross.
The pole kept going during the 20th century, north at an average speed of 10 km per year, lately accelerating "to 40 km per year," says Newitt. At this rate it will exit North America and reach Siberia in a few decades. Keeping track of the north magnetic pole is Newitt's job. "We usually go out and check its location once every few years," he says. "We'll have to make more trips now that it is moving so quickly." Earth's magnetic field is changing in other ways, too: Compass needles in Africa, for instance, are drifting about 1 degree per decade. And globally the magnetic field has weakened 10% since the 19th century. When this was mentioned by researchers at a recent meeting of the American Geophysical Union, many newspapers carried the story. A typical headline: "Is Earth's magnetic field collapsing?" Probably not. As remarkable as these changes sound, "they're mild compared to what Earth's magnetic field has done in the past," says University of California professor Gary Glatzmaier.
Sometimes the the whole magnetic field of Earth completely flips. The north and the south poles swap places. Such reversals, recorded in the magnetism of ancient rocks, are unpredictable. They come at irregular intervals averaging about 300,000 years; the last one was 780,000 years ago. Are we overdue for another? No one knows.
Last week, a video of this mysterious blob floating 5000 feet under the sea was all over the Internet. Was it a whale placenta? A jellyfish? After some collective ooing and aahing, folks on the interwebs put their thinking hats on. Craig McClain at Deep Sea News dug through the literature and found a 1988 paper describing just such a jellyfish, calling it Deepstaria reticulum.
Now the Monterey Bay Aquarium Research Institute has posted a stunning video of Deepstaria jellyfish. Watch it to learn more about Deepstaria—and to look at pretty images. Win win for a Friday afternoon.
Quando ondas tomaram tamanhos quase titânicos e salvaram uma cidade grega das garras de um exército persa há aproximadamente 2.500 anos, Heródoto registrou o evento como um ato de misericórdia do deus dos mares, Poseidon...
L’homme moderne c’est-à-dire toute la population terrestre sans exception, noirs, blancs, jaunes, peaux rouges sont des descendants d’un groupe de quelques 10 000 Africains noirs environ. L’équivalent d’un grand village congolais. Ce groupe a marqué de son empreinte indélébile la planète toute entière…