- me: *owns 264 unread books*
- me: *buys 17 new books*
- me: *rereads harry potter*
Images: 1) P. vortex exposed to a chemotherapy substance 2) P. vortex 3) Vortex Blue (P. vortex) 4) A close look at P. dendritiformis 5) Bacterial Dragon (Paenibacillus dendritiformis)
Israeli physicist Eshel Ben-Jacob uses bacteria as an art medium, shaping colonies in petri dishes into bold patterns
Major Galaxy Mergers Led to the Formation Early Supermassive Black Holes
At the center of most galaxies in the observable universe there’s a supermassive black hole (SMBH). How these black holes formed has been an open question. “The presence of such massive BHs at such early times, when the Universe was less than a billion years old, implies that they grew via either super-Eddington accretion, or nearly uninterrupted gas accretion near the Eddington limit” said Takamitsu Tanaka with the Max Plank Institute for Astrophysics. According to Tanaka, “major mergers of galaxies have long been associated with quasar activity.”
The objects in question are luminous quasars at a redshift z >∼ 6 or when the universe was roughly 900 Myr old (900 million years after the Big Bang). Tanaka reasons that these supermassive black holes accreted mass continuously at the Eddington limit or they went through periods of super-Eddington accretion. Continuous accretion at the Eddington limit doesn’t fit observations at lower redshifts like z >~ 2 where accretion occurs for 1 to 100 Myr. Cosmological redshift is a combination of Doppler, cosmological expansion and other effects. However, the cosmological redshift dominates over other effects once z > ~.01 or when the universe is 12.5 Gyr old. Distant objects can be used to study cosmic history because high redshift implies large distances. This also implies that when a given object emitted light, the universe was younger. The Eddington limit is the theoretical estimate for the maximum luminosity an object, like a star, can reach given a balance between the gravitational force acting inward and the force of radiation acting outward. According to Tanaka, “light exerts a force and so a significantly bright object can counter its own gravitational pull.” The luminosity of a quasar, for instance, could stop gas from falling in.
In a correspondence, Tanaka said that “for z > ~6 SMBHs to have grown to a billion solar masses in less than a billion years since the Big Bang, their time-averaged accretion rate must have been close to the Eddington limit, something like 60-80%.” He added that “they could achieve this if they are growing at the Eddington limit 80% of the time, or if they are growing at 80% of the Eddington limit 100% of the time, or something in between. That would mean that SMBHs were growing almost continuously. This sounds a little uncomfortable to many astronomers, because SMBHs grow only a small fraction of the time at lower redshifts, which is where we’ve built up most of our knowledge about quasars and SMBHs.”
Galaxy mergers can explain the growth of SMBHs in the early universe. If a major merger—that is a merger between two objects of comparable mass, like the impending merger between the Milky Way and M31—triggers a quasar or the growth of an SMBH in our local universe or at z < 1, when the black hole is done feeding, another merger doesn’t occur for billions of years. The feeding period is much shorter than the time between mergers and thus, SMBH growth is rare in the local universe. This same scenario had different results in the early universe or at z > 10 since the period between mergers is comparable to or even shorter than the feeding time. Black holes could have been fed continuously. This agrees with the galaxy merger rate, which is held to have been higher in the early universe.
Tanaka proposes an ansatz “that for the most part, the evolution of galaxies and their SMBHs are governed by how massive they are. Galaxies had already grown to be very massive by z > 6, and in the process their central black holes had grown very massive.” He suggests the possibility that SMBHs and galaxies formed and evolved without the need for rare mechanisms like super-Eddington accretion. SMBHs grew due to frequent mergers between galaxies and feeding times that were mostly uninterrupted.
Edited on June 21, 2014: The original article used doppler shift and redshift interchangeably. This wasn’t accurate. Also, the symbol ~ doesn’t equal 650 Myr. The symbol ~ can be read as around, which is a looser variation of approximately equal to. The original article also included some information related to a paper that wasn’t relevant to Tanaka’s paper. Vegetti’s paper focuses on clusters in the local universe.
Journal Reference: http://arxiv.org/abs/1406.3023
More information can be found online:
The problem of choosing an optimal strategy for moving in the rain has attracted considerable attention among physicists and other scientists. Taking a novel approach, this paper shows, by studying simple shaped bodies, that the answer depends on the shape and orientation of the moving body and on wind direction and intensity. For different body shapes, the best strategy may be different: in some cases, it is best to run as fast as possible, while in some others there is an optimal speed.
Where do our planet’s oceans come from? New research done in part at Brookhaven shows it may come from the rocks deep in the Earth’s mantle.
The water is trapped inside a blue rock called ringwoodite that sits between the Upper Mantle and Lower Mantle in a spot called the Transition Zone about 450 miles beneath the Earth’s surface.
Northwestern geophysicist Steve Jacobsen and University of New Mexico seismologist Brandon Schmandt have found deep pockets of magma in this zone, an indicator of water that is squeezed out of the rocks by enormous pressures and temperatures.
Jacobsen and his team used a diamond-anvil cell at one of the UV beamlines at our National Synchrotron Light Source to mimic those pressures on a sample of ringwoodite. Compressed between two tiny diamonds and laser-heated to almost 3000 degrees Fahrenheit, the sample sweated out its water.
But it’s not in a form familiar to us — it’s not liquid, ice, or vapor. It’s water trapped in the molecular structure of the minerals in the mantle rock. If just one percent of the weight of mantle rock located in the Transition Zone is H2O, that would be equivalent to nearly three times the amount of water in our oceans!!
Magnesium chloride, a chemical used to make tofu and bath salts, can replace the harmful and costly cadmium chloride in solar cells.
A toxic and expensive compound called cadmium chloride is used to make solar cells. Solar cell manufacturers have been forced to adopt strict safety measures to ensure their workers are protected when using this substance.
Researchers at the University of Liverpool in the UK have found that magnesium chloride, a chemical extracted from seawater that’s used to make tofu and bath salts, can replace cadmium chloride, providing a safe and cheaper option for solar cell manufacturers. One gram of cadmium chloride costs US$0.3 dollars whereas a gram of magnesium chloride costs only US$0.001 dollars.
“If renewable energy is going to compete with fossil fuels, then the cost has to come down. Great strides have already been made, but the findings in this paper have the potential to reduce costs further,” lead author of the study, physicist Jon Major, said in a release.
“Cadmium chloride is toxic and expensive and we no longer need to use it. Replacing it with a naturally occurring substance could save the industry a vast amount of money and reduce the overall cost for generating power from solar.”
The results of this study were published in the journal Nature.
Materials scientist John Rogers and his firm MC10 have developed flexible electronic circuits that stick directly to the skin like temporary tattoos and monitor the wearer’s health. The Biostamp is a thin electronic mesh that stretches with the skin and monitors temperature, hydration and strain.
(NASA) Puffing Sun Gives Birth To Reluctant Eruption
A suite of NASA’s sun-gazing spacecraft have spotted an unusual series of eruptions in which a series of fast puffs forced the slow ejection of a massive burst of solar material from the sun’s atmosphere. The eruptions took place over a period of three days, starting on Jan. 17, 2013. Nathalia Alzate, a solar scientist at the University of Aberystwyth in Wales, presented findings on what caused the puffs at the 2014 Royal Astronomical Society’s National Astronomy Meeting in Portsmouth, England.
The sun’s outermost atmosphere, the corona, is made of magnetized solar material, called plasma, that has a temperature of millions of degrees and extends millions of miles into space. On Jan. 17, the joint European Space Agency and NASA’s Solar and Heliospheric Observatory, or SOHO, spacecraft observed puffs emanating from the base of the corona and rapidly exploding outwards into interplanetary space. The puffs occurred roughly once every three hours. After about 12 hours, a much larger eruption of material began, apparently eased out by the smaller-scale explosions.
Meet the red-eyed gaper, Chaunax sp., more commonly known as “by-catch” in commercial fishery operations. Gapers are Lophiformes, in the anglerfish group, with big heads, a network of open sensory canals,
and a lateral canal extending posteriorly along a compressed trunk and tail. They are sit-and-wait, ambush predators. These red-eyed gapers and their ilk can be found as deep as 2000 m around the world.
- Credit: Anne Richards, NEFSC/NOAA
NASA To Aliens: Stay Tuned For A Group Message From Humanity:
Apparently, NASA doesn’t worry too much that hostile aliens might receive a message from Earth and say, in so many of their word-forms, “Thanks for the invitation.”
That must be the attitude of this most optimistic of governmental agencies, considering news that the New Horizons spacecraft is expected to carry a digital greeting from our species as it heads out of our solar system.
Right now, New Horizons is somewhere beyond Jupiter, hurtling toward a flyby of ex-planet Pluto in about a year. Launched in 2006, the probe’s job description includes taking the first close photos of Pluto’s surface and, after that, exploration of the asteroid-and-planetoid traffic jam otherwise known as the Kuiper Belt.
At that point, the plan is to transmit a digital message representing humanity to the craft, safely tucked inside until some alien can read it and decide whether we’re worth invading.
The previous four Earth-born objects to leave the solar system — Pioneers 10 and 11 and Voyagers 1 and 2 — all carried greetings for extraterrestrials. The Pioneers had message plaques, and the Voyagers bore Golden Records. So we didn’t want the aliens to think, when they gobbled up New Horizons, that we weren’t still thinking of them.
Last September, the Hawaii-based New Horizons Message Initiative (NHMI) launched a petition to transmit a One Earth message to New Horizons.
The effort was conceived and developed by astronomical artist Jon Lomberg, who was the design director for the Voyager Golden Records and a collaborator of astronomer and science educator Carl Sagan. He announced in May that, in response to the petition, NASA has given thumbs up to the project.
The plaques and records, however, were intended to last eons, while the computer storage of the message on New Horizons is expected to last only a few decades — unless, of course, the aliens have some killer message-recovering tech.
NHMI wants the 100MB message to represent a self-portrait of planet Earth, although it’s not yet clear if the planet can sit still long enough to get a good one. To make what NHMI is calling the digital “human fingerprint” will require the combined effort of scientists, artists, writers, musicians, entertainers, and “the input of people from every walk of life and many different perspectives.”
The names of the first 10,000 humans who signed the petition to NASA will also be included in the message. Content finalists will be determined by online voting — but, fortunately for Earth’s reputation out there, NHMI and NASA will have final approval.
At the very least, the alien recipients might get an enjoyable relief from their weird life.
The collection and merging of those many content contributions over the next three years will cost about $500,000, which will be entirely funded with non-NASA money via a Kickstarter campaign conducted by NHMI. It is expected to kick off in August.
The ear is an important organ that allows us to perceive the world around us. However, very few of us are aware that not only the ear cup but also our skull bone can receive and conduct sounds. Tatjana Tchumatchenko from the Max Planck Institute for Brain Research in Frankfurt and Tobias Reichenbach from Imperial College London have now developed a new model explaining how the vibrations of the surrounding bone and the basilar membrane are coupled. These new results can be important for the development of new headphones and hearing devices.
Our sense of hearing, which is the ability to perceive sounds, arises exclusively in the inner ear. When sound waves travel through the air and reach our ear canal they cause different regions of the basilar membrane in the inner ear to vibrate. Which regions of the membrane they vibrate depends on their frequency. It is these microscopic vibrations of the membrane that we perceive as sound. However, the inner ear is surrounded by a bone that can also vibrate.
With the help of fluid dynamics calculations Tchumatchenko and Reichenbach have now discovered that the vibrations of the bone and basilar membrane are coupled. In other words, they can also mutually excite each other.
This gives rise to fascinating phenomena which, thanks to the new model, can now be understood: For example, two sounds with slightly different frequencies that arrive in the inner ear at the same time can overlap and excite the same regions on the basilar membrane. In this case, combination tones, or so-called otoacoustic emissions, are produced in the inner ear through the nonlinearity of the membrane. Precisely how these sounds leave the inner ear and how they spread inside the cochlea is currently a matter of scientific debate. “In our study we have shown that the combination tones can leave the inner ear in the form of a fast wave along the bone surface, and not, as previously assumed, by a wave along the basilar membrane,” explains Tatjana Tchumatchenko from the Max Planck Institute for Brain Research.
Moreover, the new model proves that the travelling waves along the basilar membrane can be generated by both the vibrations of the cochlear bone and the vibrations of the air inside the ear canal. “Our results provide an elegant explanation for this long-known but poorly understood observation,” says Tobias Reichenbach from Imperial College London.
These results will help advance our understanding of the complex interaction between the dynamics of fluids and the mechanics of the bone. This understanding can prove essential for ever more fascinating future clinical and commercial applications of bone conduction, such new-generation hearing aids and combinations between headphones and glasses.
All of this was based on the pioneering work for Andrija Puharich.
GoT: fan art
Art director and designer Jerry Liu has designed a series of minimalist prints of popular characters from Game of Thrones.