While millions of people are out hunting Pokémon, biologists are conducting an equally fervent hunt for new and rare species. And instead of 151 species, they estimate that they need to find another 4,000 or so before they become the very best.
A new study builds a compendium of all the tree species collected from the Amazon over past three centuries, and concludes that we won’t find them all until 2316. In total, researchers from the Field Museum say researchers have, so far, collected 11,676 unique tree species from the Amazon rainforest, and that there are likely some 16,000 there in total, based on recent projections. Read More
In the quest for dark energy, astronomers have created an unprecedented 3-D map of galaxies in a volume of about 650 cubic billion light years.
Hundreds of astronomers from the Sloan Digital Sky Survey III (SDSS-III) and the Max Planck Institutes for Extraterrestrial Physics (MPE) and for Astrophysics (MPA) contributed to this map. The astronomers found that the map agrees with the current cosmological model (the Lambda Cold Dark Matter model) and confirmed that dark energy is a cosmological constant.
Understanding how dark energy interacts and affects our universe is crucial to unraveling how the universe came to be and how it may end. Dark energy is believed to be what contradicts the force of gravity and is what is accelerating the expansion of the universe. These findings were submitted to the Monthly Notices of the Royal Astronomical Society (MNRAS) as a collection of papers.
“We have spent a decade collecting measurements of 1.2 million galaxies over one quarter of the sky to map out the structure of the universe over a volume of 650 cubic billion light-years,” says Dr. Jeremy Tinker of New York University in a press release.
The Baryon Oscillation Spectroscopic Survey (BOSS) of the SDSS-III carried out the precise measurements found. By studying the tugs between dark energy and dark matter, the scientists were able to determine the Baryonic Acoustic Oscillation (BAO) between the galaxies in the map to measure the expansion rate of the universe.
The normal BAO size is found from pressure waves that traveled throughout the universe when it was only 400,000 years old (the universe is currently 13.8 billion years old). The distribution of matter throughout the galaxy represents a frozen image of the life of these waves. All galaxies are therefore separated preferentially by a characteristic distance in what is called the BAO scale.
Using observations from the cosmic microwave background (CMB), the size of the acoustic scale at the universe’s current age can be determined. This is because the light that is emitted corresponds to when the pressure waves became frozen. Seeing how the distribution of galaxies has changed since then can give astronomers clues to how dark energy and dark matter have battled over the expansion rate of the universe. Ariel Sanchez, from MPE, was the astronomer who led the search to find the total amounts of dark energy and dark matter in the universe.
“Measuring the acoustic scale across cosmic history gives a direct ruler with which to measure the universe’s expansion rate,” says Sanchez in the same press release. “ With BOSS, we have traced the BAO’s subtle imprint on the distribution of galaxies spanning a range of time from 2 to 7 billion years ago.”
These very precise measurements had to be analyzed many times, in particular the distances from Earth to the galaxies in the map. Using a spectrometer, the light from a galaxy appears red-shifted as it is moving away from us. The red-shift in light is how the astronomers were able to correlate the galaxy’s distance from Earth; the farther a galaxy is, the faster it moves and therefore the more it is red-shifted. Dr. Shun Saito from MPA contributed models to the BOSS data analysis.
“However, galaxies also have peculiar motions and the peculiar velocity component along the line-of-sight leads to the so-called redshift space distortion,” says Saito in the same press release. “This makes the galaxy distribution anisotropic because the line-of-sight direction is now special — only along this direction the distance is measured through a redshift, which is contaminated by peculiar velocity. In other words, the characteristic anisotropic pattern allows us to measure the peculiar velocity of galaxies — and because the motion of galaxies is governed by gravity, we can use this measurement to constrain to what level Einstein’s general relativity is correct at cosmological scales. In order to properly interpret the data, we have developed a refined model to describe the galaxy distribution.”
Another possible approach is to use the angular positions of the galaxies in the sky rather than the 3-D physical positions in the universe.
“This method uses only observables,” says Dr. Salvador Salazar, a junior MPE researcher, in the same press release. “We make no prior assumptions about the cosmological model.”
Many approaches have been used to try and analyze the huge BOSS data set. “We now have seven measurements, which are slightly different, but highly correlated,” Sanchez says in a separate press release. “To extract the most information about the cosmological parameters, we had to find not only the best methods and models for data analysis but also the optimal combination of these measurements.”
Their strenuous efforts have paid off as the BOSS data show that dark energy is causing the expansion of the universe with an error of only 5 percent in the cosmological constant found. The cosmological constant is called Lambda, as coined by Albert Einstein as a repellant effect in the universe. These findings are still consistent with the relatively young theory of the cosmological model.
The map also reveals that galaxies tend to move to areas with more matter, staying true to the laws of gravity as well as the infall of material following the laws of general relativity. This suggests that the idea of the expansion of the universe is caused by a phenomenon like dark energy that works on large cosmic scales and dismisses the notion that our laws of gravity are breaking down.
This post originally appeared on Astronomy.com.
The struggle between humans and viruses stretches back far into the dusty depths of history, and it appears that we wear the scars of this epic battle in that most personal of places: our genome.
Whenever a viral epidemic tears through a community, there are those lucky enough to possess mutations rendering them immune to the disease. If the epidemic is large enough, this mutation can become embedded in our genome, both because of its protective powers, and because those with it will be overrepresented in the surviving population.
Many of the genetic alterations wrought by viruses ares still present in our genome today, and in a new paper, researchers at Stanford University suggests that as much as 30 percent of the adaptions seen in our proteins since the split with chimpanzees millions of years ago could be a direct result of viral infections. Read More
When you step off a plane in another country, the first thing you usually want to do is hit the hay. It’s the sleepy side effect of travel known as jet lag.
Experienced travelers power through fatigue and wait until nighttime to get some shut-eye in an attempt to match the natural cycles of their new locale. While some people acclimate to time-zone jumping better than others, most agree that traveling eastward is a more daunting challenge to our sleep cycle, but it’s not clear why that is. Read More
On July 4, space enthusiasts awaited word that the Juno probe had entered orbit around Jupiter. The journey was perilous, as the craft was going incredibly fast. Once that was done, it turned its solar panels towards the sun and began its first orbit. Now, a safe distance from Jupiter has been attained and the system is slowly coming online, giving NASA its first photo opportunity since it made its own jovian fireworks. Read More
A first-of-its-kind underwater microscopic imaging system is giving scientists an up-close perspective on the frenzied daily lives of corals.
Corals appear fairly sedate when viewed from on high, but they’re abuzz with activity that occurs on scales too small for us to see with the naked eye. Fully zoomed in, scientists observed coral polyps engaging in the “three Fs” of existence: fighting, feasting and…making love within their vast colonies. Spying on the way coral engage in these essential behaviors will give researchers new insights into how the coral communities live and how they die — important work during a period of unprecedented bleaching events. Read More
A new study on the possible health benefits of thumb sucking bolsters the decades-old, controversial “hygiene hypothesis,” which claims that exposure to some bacteria early in life could improve health down the road.
The latest results come from the Dunedin Multidisciplinary Study, which has followed more than 1,000 people in New Zealand over four decades. Researchers from the University of Otago used the data to see if thumb-sucking and nail biting, both common childhood behaviors, were correlated with lower rates of allergic reactions later in life. Read More
There are plenty of weird planets in the Milky Way, but HD 131399Ab may be one of the weirdest.
Discovered in a survey of 100 young stars, the 16 million-year-old planet still glows hot enough for astronomers to image it directly. Somehow in those short few million years, it migrated out 80 astronomical units (AU; one AU is the average Earth-Sun distance) from its parent star.
But also accompanying the parent star, which is a little bit bigger than the Sun, are two companion stars in orbit around each other at a distance of 300 to 400 AU. Read More
Researchers have genetically engineered mice to be super smellers, and they could one day be used to help detect land mines, diagnosis diseases or make perfume with just the right amount of musk.
A team led by biologist Paul Feinstein of Hunter College in New York modified the genetic code of mouse embryos to produce mice with more neurons tuned to detect specific odors. Apart from homing in on targeted scents, the so-called MouSensor mice could also help answer basic questions about how humans smell.
“Sense of smell is one of our most fundamental senses, and it’s really abysmal that in 25 years we still don’t know how it’s coded,” says Feinstein. “This could be the trick that gets us to understand.”
The 25-year milestone—to which Feinstein refers—is when researchers discovered a family of genes that code for odor receptors, located in olfactory neurons of the nose. Each gene codes for one type of receptor, which can only detect a limited set of odors. Signals from olfactory neurons ultimately converge in the brain, allowing us to experience an array of smells and the memories they evoke.
What we don’t understand—and what MouSensors may reveal—is how the olfactory system is genetically programmed to wire itself.
Mice have about 1,000 types of odor receptors, while humans have roughly 400. The types are distributed amongst millions of olfactory neurons, so that only about 0.1 percent of neurons have the same receptors, making the nose a “broad detector sheet,” says Feinstein.
“The system is rigged so everyone has a fair shake at being expressed,” explains Feinstein. He sought to alter the odds, and “force the neuron to choose the receptor that I was interested in.”
In MouSensors, Feinstein and colleagues added an enhancer gene that increased the number of neurons with specific odor receptors, above the normal 0.1 percent distribution. They created one line of mice that had 1 to 2 percent of neurons devoted to a receptor for acetophenone molecules, which smell sweet like jasmine. Another mouse line had 13 percent of neurons with receptors that could detect carvone molecules that smell like mint.
The increased concentration of neurons altered the mice’s brains and behavior: Fluorescent imaging showed the extra receptors were indeed activating the correct neural pathway through the brain, and the MouSensors could smell the target odors at much lower concentrations than regular mice. The researchers trained both regular and MouSensor mice to avoid the odors by pairing them with injections of a chemical that causes “gastric malaise,” or stomachache.
The mice were then given a choice between pure water or water laced with decreasing concentrations of the odor molecules. Compared to normal mice, the acetophenone-tuned mice were about twice as sensitive to the odors, and the carvone-tuned mice were about 100 times as sensitive. The team published its results Thursday in Cell Reports.
The MouSensor technology—the ability to increase the number of neurons with specific odor receptors—has far reaching applications. The flavor and fragrance industry could use the mice to better understand odor detection and then design products more efficiently. The Department of Defense has funded the Feinstein group to develop super-smeller rats that could sniff-out explosives.
MouSensors could also have important medical applications. Odors below the limits of human detection may signal that a person has a disease, even before symptoms manifest.
“Every disease is going to change your body chemistry in some way … Can we create a platform to detect it and use it as a diagnostic tool?” says Feinstein.
People who have lost their sense of smell—through normal aging or neurological disorders—often become undernourished because smell is integral to appetite. MouSensor technology may pave the way for restoring this vital function.
Those possibilities are “just scratching the surface of what we can do,” says Feinstein. “We hope to make our dreams come true and decode human olfaction.”
Drinking alcohol doesn’t only lower our inhibitions on the dance floor, it also directly affects the structures in our brains that inhibit our desire to drink.
Specifically, alcohol influences the dopamine receptors that convince us to start drinking and tell us when its time to stop. The more often we drink, the greater the effect, proving something that even casual drinkers are well aware of: nothing gets you in the mood for another beer like having a beer.
Alcohol prompts the release of dopamine in our brains, the “feel-good” chemical that is responsible for eliciting sensations of pleasure. But dopamine has a darker side: Drugs that flood our brain with the chemical can make our brain dependent on that outsize reward, leading to addiction. And it’s more than just the amount of dopamine that leads to addiction. In a pair of studies in mice, researchers from Texas A&M University show that specific receptors in the brain may adapt when exposed to high levels of dopamine, reshaping itself to more readily react to the chemical. Read More