Silicon Rival MoS2 Promises Small, Low-Energy Chips
|7:43:25 PM, Monday, December 05, 2011|
"The first computer chip made out of a substance described as a "promising" alternative to silicon has been tested by researchers.
The Switzerland-based team used molybdenite disulfide (MoS2) - a dark-coloured, naturally occurring mineral.
The group said the substance could be used in thinner layers than silicon, which is currently the most commonly used component in electronics.
It said MoS2 could make smaller, more flexible chips that used less energy.
The substance is currently used as an ingredient in engine lubricants, ski waxes and as a strengthening agent for plastics.
Prof Andras Kis, the director of the Laboratory of Nanoscale Electronics and Structures (LANES) in Lausanne, published details of the research in the latest edition of the ACS Nano journal.
He said the team chose to experiment with this semiconductor, rather than another material, in part because it was easily available.
"There is something like 19 million metric tonnes around," Prof Kis told the BBC.
"You can just go on some websites on the internet and buy a 1cm by 1cm crystal for around $100 [Ł64]."
To obtain a thin layer of the material to work with, Prof Kis's team put a strip of sticky plastic over the crystal, peeled it off and then attached the sliver to a support. The plastic was then peeled off to leave the very thin layer of MoS2 exposed.
Using this, the team built a prototype microchip circuit to which they attached up to six serial transistors allowing them to carry out simple logic operations.
Although the integrated circuit was basic, Prof Kis said it proved that more complex designs would be possible on thinner chips than could be produced with silicon.
"The problem with silicon is that you cannot make very thin things from it because it is very reactive," he said.
"The surface likes to oxidise - to bind with oxygen and hydrogen - and that makes its electrical properties degrade when you want to make a very thin film."
As a result the thinnest usable layers of silicon used in computer chips have been around two nanometres thick. MoS2, by contrast, can be used in layers just three atoms thick, allowing chips to be made at least three times smaller.
Stiff as steel
A key advantage of having a thinner material is that the transistors can also be shrunk in size.
"If you have a transistor that is very thin it will also automatically dissipate less power - so it spends less power. So in a nutshell it allows you to make electronics that spend less electrical energy," Prof Kis said.
MoS2 also has the advantage that it is as stiff as stainless steel, but is also capable of being flexible.
"It can be bent to large angles and can be stretched a lot," said Prof Kis.
"If you take a sheet of molybdenite you can stretch it so that it increases its length by 10% - that is a lot in this context.
"If you did the same with silicon it would break like glass."
Astronomers Discover Biggest Black Holes Ever
|5:40:59 PM, Monday, December 05, 2011|
"University of California, Berkeley, astronomers have discovered the largest black holes to date two monsters with masses equivalent to 10 billion suns that are threatening to consume anything, even light, within a region five times the size of our solar system.
These black holes are at the centers of two galaxies more than 300 million light years from Earth, and may be the dark remnants of some of the very bright galaxies, called quasars, that populated the early universe.
"In the early universe, there were lots of quasars or active galactic nuclei, and some were expected to be powered by black holes as big as 10 billion solar masses or more," said Chung-Pei Ma, UC Berkeley professor of astronomy. "These two new supermassive black holes are similar in mass to young quasars, and may be the missing link between quasars and the supermassive black holes we see today."
Black holes are dense concentrations of matter that produce such strong gravitational fields that even light cannot escape. While exploding stars, called supernovas, can leave behind black holes the mass of a single star like the sun, supermassive black holes have presumably grown from the merger of other black holes or by capturing huge numbers of stars and massive amounts of gas.
"These black holes may shed light on how black holes and their surrounding galaxies have nurtured each other since the early universe," said UC Berkeley graduate student Nicholas McConnell, first author of a paper on the discovery being published in the Dec. 8 issue of the British journal Nature by McConnell, Ma and their colleagues at the university of Toronto, Texas and Michigan, as well as by the National Optical Astronomy Observatory in Arizona.
To date, approximately 63 supermassive black holes have been found sitting in the cores of nearby galaxies. The largest for more than three decades was a 6.3 billion solar mass black hole in the center of the nearby galaxy M87.
One of the newly discovered black holes is 9.7 billion solar masses and located in the elliptical galaxy NGC 3842, the brightest galaxy in the Leo cluster of galaxies, 320 million light years away in the direction of the constellation Leo. The second is as large or larger and sits in the elliptical galaxy NGC 4889, the brightest galaxy in the Coma cluster about 336 million light years from Earth in the direction of the constellation Coma Berenices.
According to McConnell, these black holes have an event horizon – the "abandon all hope" edge from which not even light can escape – that is 200 times the orbit of Earth, or five times the orbit of Pluto. Beyond the event horizon, each black hole has a gravitational influence that would extend over a sphere 4,000 light years across.
"For comparison, these black holes are 2,500 times as massive as the black hole at the center of the Milky Way Galaxy, whose event horizon is one fifth the orbit of Mercury," McConnell said..."
Kepler 22-b: Earth-Like Planet Confirmed
|5:32:30 PM, Monday, December 05, 2011|
"Astronomers have confirmed the existence of an Earth-like planet in the "habitable zone" around a star not unlike our own.
The planet, Kepler 22-b, lies about 600 light-years away and is about 2.4 times the size of Earth, and has a temperature of about 22C.
It is the closest confirmed planet yet to one like ours - an "Earth 2.0".
However, the team does not yet know if Kepler 22-b is made mostly of rock, gas or liquid.
During the conference at which the result was announced, the Kepler team said that it had spotted some 1,094 new candidate planets.
The Kepler space telescope was designed to look at a fixed swathe of the night sky, staring intently at about 150,000 stars. The telescope is sensitive enough to see when a planet passes in front of its host star, dimming the star's light by a minuscule amount.
Kepler identifies these slight changes in starlight as candidate planets, which are then confirmed by further observations by Kepler and other telescopes in orbit and on Earth.
Kepler 22-b was one of 54 candidates reported by the Kepler team in February, and is just the first to be formally confirmed using other telescopes.
More of these "Earth 2.0" candidates are likely to be confirmed in the near future, though a redefinition of the habitable zone's boundaries has brought that number down to 48.
Kepler 22-b lies at a distance from its sun about 15% less than the distance from the Earth to the Sun, and its year takes about 290 days. However, its sun puts out about 25% less light, keeping the planet at its balmy temperature that would support the existence of liquid water.
The Kepler team had to wait for three passes of the planet before upping its status from "candidate" to "confirmed".
"Fortune smiled upon us with the detection of this planet," said William Borucki, Kepler principal investigator at Nasa's Ames Research Center.
"The first transit was captured just three days after we declared the spacecraft operationally ready. We witnessed the defining third transit over the 2010 holiday season."
The results were announced at the Kepler telescope's first science conference, alongside the staggering number of new candidate planets. The total number of candidates spotted by the telescope is now 2,326 - of which 207 are approximately Earth-sized.
In total, the results suggest that planets ranging from Earth-sized to about four times Earth's size - so-called "super-Earths" - may be more common than previously thought."
Your Brain Knows a Lot More Than You Realize
|1:12:18 AM, Wednesday, November 30, 2011|
"Only a tiny fraction of the brain is dedicated to conscious behavior. The rest works feverishly behind the scenes regulating everything from breathing to mate selection. In fact, neuroscientist David Eagleman of Baylor College of Medicine argues that the unconscious workings of the brain are so crucial to everyday functioning that their influence often trumps conscious thought. To prove it, he explores little-known historical episodes, the latest psychological research, and enduring medical mysteries, revealing the bizarre and often inexplicable mechanisms underlying daily life.
Eagleman’s theory is epitomized by the deathbed confession of the 19th-century mathematician James Clerk Maxwell, who developed fundamental equations unifying electricity and magnetism. Maxwell declared that “something within him” had made the discoveries; he actually had no idea how he’d achieved his great insights. It is easy to take credit after an idea strikes you, but in fact, neurons in your brain secretly perform an enormous amount of work before inspiration hits. The brain, Eagleman argues, runs its show incognito. Or, as Pink Floyd put it, “There’s someone in my head, but it’s not me.”
There is a looming chasm between what your brain knows and what your mind is capable of accessing. Consider the simple act of changing lanes while driving a car. Try this: Close your eyes, grip an imaginary steering wheel, and go through the motions of a lane change. Imagine that you are driving in the left lane and you would like to move over to the right lane. Before reading on, actually try it. I’ll give you 100 points if you can do it correctly.
It’s a fairly easy task, right? I’m guessing that you held the steering wheel straight, then banked it over to the right for a moment, and then straightened it out again. No problem.
Like almost everyone else, you got it completely wrong. The motion of turning the wheel rightward for a bit, then straightening it out again would steer you off the road: you just piloted a course from the left lane onto the sidewalk. The correct motion for changing lanes is banking the wheel to the right, then back through the center, and continuing to turn the wheel just as far to the left side, and only then straightening out. Don’t believe it? Verify it for yourself when you’re next in the car. It’s such a simple motor task that you have no problem accomplishing it in your daily driving. But when forced to access it consciously, you’re flummoxed.
The lane-changing example is one of a thousand. You are not consciously aware of the vast majority of your brain’s ongoing activities, nor would you want to be—it would interfere with the brain’s well-oiled processes. The best way to mess up your piano piece is to concentrate on your fingers; the best way to get out of breath is to think about your breathing; the best way to miss the golf ball is to analyze your swing. This wisdom is apparent even to children, and we find it immortalized in poems such as “The Puzzled Centipede”:
A centipede was happy quite,
Until a frog in fun
Said, “Pray tell which leg comes after which?”
This raised her mind to such a pitch,
She lay distracted in the ditch
Not knowing how to run.
The ability to remember motor acts like changing lanes is called procedural memory, and it is a type of implicit memory—meaning that your brain holds knowledge of something that your mind cannot explicitly access. Riding a bike, tying your shoes, typing on a keyboard, and steering your car into a parking space while speaking on your cell phone are examples of this. You execute these actions easily but without knowing the details of how you do it. You would be totally unable to describe the perfectly timed choreography with which your muscles contract and relax as you navigate around other people in a cafeteria while holding a tray, yet you have no trouble doing it. This is the gap between what your brain can do and what you can tap into consciously.
The concept of implicit memory has a rich, if little-known, tradition. By the early 1600s, René Descartes had already begun to suspect that although experience with the world is stored in memory, not all memory is accessible. The concept was rekindled in the late 1800s by the psychologist Hermann Ebbinghaus, who wrote that “most of these experiences remain concealed from consciousness and yet produce an effect which is significant and which authenticates their previous existence.”
To the extent that consciousness is useful, it is useful in small quantities, and for very particular kinds of tasks. It’s easy to understand why you would not want to be consciously aware of the intricacies of your muscle movement, but this can be less intuitive when applied to your perceptions, thoughts, and beliefs, which are also final products of the activity of billions of nerve cells. We turn to these now.
Chicken Sexers and Plane Spotters
When chicken hatchlings are born, large commercial hatcheries usually set about dividing them into males and females, and the practice of distinguishing gender is known as chick sexing. Sexing is necessary because the two genders receive different feeding programs: one for the females, which will eventually produce eggs, and another for the males, which are typically destined to be disposed of because of their uselessness in the commerce of producing eggs; only a few males are kept and fattened for meat. So the job of the chick sexer is to pick up each hatchling and quickly determine its sex in order to choose the correct bin to put it in. The problem is that the task is famously difficult: male and female chicks look exactly alike.
Well, almost exactly. The Japanese invented a method of sexing chicks known as vent sexing, by which experts could rapidly ascertain the sex of one-day-old hatchlings. Beginning in the 1930s, poultry breeders from around the world traveled to the Zen-Nippon Chick Sexing School in Japan to learn the technique.
The mystery was that no one could explain exactly how it was done. It was somehow based on very subtle visual cues, but the professional sexers could not say what those cues were. They would look at the chick’s rear (where the vent is) and simply seem to know the correct bin to throw it in.
And this is how the professionals taught the student sexers. The master would stand over the apprentice and watch. The student would pick up a chick, examine its rear, and toss it into one bin or the other. The master would give feedback: yes or no. After weeks on end of this activity, the student’s brain was trained to a masterful—albeit unconscious—level..."
The Xinjiang Procedure: Beijing’s ‘New Frontier’ is Ground Zero for the Organ Harvesting of Political Prisoners
|9:12:22 PM, Tuesday, November 29, 2011|
"To figure out what is taking place today in a closed society such as northwest China, sometimes you have to go back a decade, sometimes more. Photo of Chinese Flag with surgical stitches in it
One clue might be found on a hilltop near southern Guangzhou, on a partly cloudy autumn day in 1991. A small medical team and a young doctor starting a practice in internal medicine had driven up from Sun Yat-sen Medical University in a van modified for surgery. Pulling in on bulldozed earth, they found a small fleet of similar vehicles—clean, white, with smoked glass windows and prominent red crosses on the side. The police had ordered the medical team to stay inside for their safety. Indeed, the view from the side window of lines of ditches—some filled in, others freshly dug—suggested that the hilltop had served as a killing ground for years.
Thirty-six scheduled executions would translate into 72 kidneys and corneas divided among the regional hospitals. Every van contained surgeons who could work fast: 15-30 minutes to extract. Drive back to the hospital. Transplant within six hours. Nothing fancy or experimental; execution would probably ruin the heart.
With the acceleration of Chinese medical expertise over the last decade, organs once considered scraps no longer went to waste. It wasn’t public knowledge exactly, but Chinese medical schools taught that many otherwise wicked criminals volunteered their organs as a final penance.
Right after the first shots the van door was thrust open and two men with white surgical coats thrown over their uniforms carried a body in, the head and feet still twitching slightly. The young doctor noted that the wound was on the right side of the chest as he had expected. When body #3 was laid down, he went to work.
Male, 40-ish, Han Chinese. While the other retail organs in the van were slated for the profitable foreigner market, the doctor had seen the paperwork indicating this kidney was tissue-matched for transplant into a 50-year-old Chinese man. Without the transplant, that man would die. With it, the same man would rise miraculously from his hospital bed and go on to have a normal life for 25 years or so. By 2016, given all the anti-tissue-rejection drug advances in China, they could theoretically replace the liver, lungs, or heart—maybe buy that man another 10 to 15 years.
Body #3 had no special characteristics save an angry purple line on the neck. The doctor recognized the forensics. Sometimes the police would twist a wire around a prisoner’s throat to prevent him from speaking up in court. The doctor thought it through methodically. Maybe the police didn’t want this prisoner to talk because he had been a deranged killer, a thug, or mentally unstable. After all, the Chinese penal system was a daily sausage grinder, executing hardcore criminals on a massive scale. Yes, the young doctor knew the harvesting was wrong. Whatever crime had been committed, it would be nice if the prisoner’s body were allowed to rest forever. Yet was his surgical task that different from an obstetrician’s? Harvesting was rebirth, harvesting was life, as revolutionary an advance as antibiotics or steroids. Or maybe, he thought, they didn’t want this man to talk because he was a political prisoner.
Nineteen years later, in a secure European location, the doctor laid out the puzzle. He asked that I keep his identity a secret. Chinese medical authorities admit that the lion’s share of transplant organs originate with executions, but no mainland Chinese doctors, even in exile, will normally speak of performing such surgery. To do so would remind international medical authorities of an issue they would rather avoid—not China’s soaring execution rate or the exploitation of criminal organs, but rather the systematic elimination of China’s religious and political prisoners. Yet even if this doctor feared consequences to his family and his career, he did not fear embarrassing China, for he was born into an indigenous minority group, the Uighurs.
Every Uighur witness I approached over the course of two years—police, medical, and security personnel scattered across two continents—related compartmentalized fragments of information to me, often through halting translation. They acknowledged the risk to their careers, their families, and, in several cases, their lives. Their testimony reveals not just a procedure evolving to meet the lucrative medical demand for living organs, but the genesis of a wider atrocity..."
Giant Nasa Rover Launches to Mars
|2:33:17 PM, Saturday, November 26, 2011|
"Nasa has launched the most capable machine ever built to land on Mars.
The near one-tonne rover, tucked inside a capsule, left Florida on an Atlas 5 rocket at 10:02 local time (15:02 GMT).
Nicknamed Curiosity, the rover will take eight and a half months to cross the vast distance to its destination.
If it can land safely next August, the robot will then scour Martian soils and rocks for any signs that current or past environments on the planet could have supported microbial life.
The Atlas flight lasted almost three-quarters of an hour.
By the time the encapsulated rover was ejected on a path to the Red Planet, it was moving at 10km/s (6 miles per second).
Spectacular video taken from the upper-stage of the rocket showed it drifting off into the distance.
"Our spacecraft is in excellent health and it's on its way to Mars," said Curiosity project manager Peter Theisinger.
Nasa received a first communication from the cruising spacecraft about 50 minutes after lift-off through a tracking station in Canberra, Australia.
Controllers will command a course correction manoeuvre in two weeks to refine the trajectory to the Red Planet.
The rover - also known as the Mars Science laboratory (MSL) - is due to arrive at the Red Planet in early August 2012. Then, the hard part begins - landing safely.
One senior space agency official this week called Mars the "Death Planet" because so many missions have failed to get down in one piece.
The Americans, though, have a good recent record and they believe a new rocket-powered descent system will be able to place the rover very precisely in one of the most exciting locations on the planet.
It is being aimed at a deep equatorial depression called Gale Crater, which contains a central mountain that rises some 5km (3 miles) above the plain below.
The crater was chosen as the landing site because satellite imagery has suggested that surface conditions at some point in time may have been benign enough to sustain micro-organisms.
This included pictures of sediments at the base of the peak that were clearly laid down in the presence of abundant water.
MSL is equipped with 10 sophisticated instruments to study the rocks, soils and atmosphere in Gale Crater.
The $2.5bn (Ł1.6bn) mission is funded for an initial two Earth years of operations, but MSL-Curiosity has a plutonium battery and so should have ample power to keep rolling for more than a decade.
It is likely the mechanisms on the rover will wear out long before its energy supply.
"The agency is ecstatic," observed Doug McCuistion, Nasa's Mars exploration programme director.
"We have started a new era of exploration, not just technologically but scientifically as well.
"I hope we have more work than the scientists can handle. When we get to the surface, I expect them all to be overrun with data they've never seen before. I expect the public to have images, vistas that we've never seen before.
"Down in the bottom of Gale Crater, those images are going to be just stunning I believe. It will be like sitting at the bottom of the Grand Canyon, I think.""
'US Should Freeze Deployment of Anti-Missile Systems in European Countries'
|3:12:42 AM, Friday, November 25, 2011|
"Russia is pushing hard for a joint European missile defense system with NATO, a system which is spearheaded by the US. But as of late, Moscow has been complaining about lukewarm co-operation from its Western partners.
The US should freeze the current deployment of US anti-missile systems in certain European countries, Konstantin Kosachev, the head of the State Duma Foreign Affairs Committee told RT.
At the G8 summit in France last week, Russia’s president Dmitry Medvedev said the US could spark a new arms race if it keeps building its missile defense system in Europe. According to Kosachev, there are some ways to avoid this, though “nobody believes we will ever have a joint button to be pushed simultaneously by the two participants.”
“Number one is not to take any practical steps immediately to create a future global anti-missile system. Number two is to make a legally-binding agreement on the purposes of the future system and to ensure the US or NATO system will not be aimed at Russia. And number three is to start practical co-operation on exchange of information on missile launches and to introduce certain elements of joint commander on the future integrated anti-missile system,” said Kosachev.
Whether or not the US decides to keep building up its missile defense system and military potential in Europe, and Russia’s response to that is a matter for the future negotiations, said Kosachev.
“As for tactical nuclear weapons, Russia now does not have any tactical nuclear weapons outside its borders, while the US have deployed certain amounts of these armaments in five or six European countries, so the first step to be taken here is to get tactical nuclear weapons inside national borders of each country that possesses these types of weapons and, later on, start further negotiations. When that happens, Russia will be ready to enter the process,” Kosachev said.
Missile defense, along with its global implications, is to become one of the main issues at the meeting between Russian and the NATO defense ministers in Berlin on June 9, and also of the next summit of Russia and the European Union in Nizhny Novgorod on June 9 and 10.
Russia warned it would consider withdrawing from the latest Russian-American Strategic Arms Reduction Treaty, New START, if there was no progress.
“There was no sufficient progress in any of the cases because NATO countries in Europe are not ready to take on the expenditures for the expensive system. They want the US to spend their money on European security. And in the dialogue between NATO and Russia, we discuss all possible options. But as nobody knows how NATO will behave, we are not making any progress here either,” Kosachev believes."
Mystery of Dead Sea Scroll Authors Possibly Solved
|2:57:26 AM, Friday, November 25, 2011|
"The Dead Sea Scrolls may have been written, at least in part, by a sectarian group called the Essenes, according to nearly 200 textiles discovered in caves at Qumran, in the West Bank, where the religious texts had been stored.
Scholars are divided about who authored the Dead Sea Scrolls and how the texts got to Qumran, and so the new finding could help clear up this long-standing mystery.
The research reveals that all the textiles were made of linen, rather than wool, which was the preferred textile used in ancient Israel. Also they lack decoration, some actually being bleached white, even though fabrics from the period often have vivid colours. Altogether, researchers say these finds suggest that the Essenes, an ancient Jewish sect, "penned" some of the scrolls.
Not everyone agrees with this interpretation. An archaeologist who has excavated at Qumran told LiveScience that the linen could have come from people fleeing the Roman army after the fall of Jerusalem in A.D. 70, and that they are in fact responsible for putting the scrolls into caves.
The Dead Sea Scrolls consist of nearly 900 texts, the first batch of which were discovered by a Bedouin shepherd in 1947. They date from before A.D. 70, and some may go back to as early as the third century B.C. The scrolls contain a wide variety of writings including early copies of the Hebrew Bible, along with hymns, calendars and psalms, among other works.
Nearly 200 textiles were found in the same caves, along with a few examples from Qumran, the archaeological site close to the caves where the scrolls were hidden.
Orit Shamir, curator of organic materials at the Israel Antiquities Authority, and Naama Sukenik, a graduate student at Bar-Ilan University, compared the white-linen textiles found in the11 caves to examples found elsewhere in ancient Israel, publishing their results in the most recent issue of the journal Dead Sea Discoveries.
A breakthrough in studying these remains was made in 2007 when a team of archaeologists was able to ascertain that colorful wool textiles found at a site to the south of Qumran, known as the Christmas Cave, were not related to the inhabitants of the site. This meant that Shamir and Sukenik were able to focus on the 200 textiles found in the Dead Sea Scroll caves and at Qumran itself, knowing that these are the only surviving textiles related to the scrolls.
They discovered that every single one of these textiles was made of linen, even though wool was the most popular fabric at the time in Israel. They also found that most of the textiles would have originally been used as clothing, later being cut apart and re-used for other purposes such as bandages and for packing the scrolls into jars.
Some of the textiles were bleached white and most of them lacked decoration, even though decoration is commonly seen in textiles from other sites in ancient Israel.
According to the researchers the finds suggest that the residents of Qumran dressed simply.
"They wanted to be different than the Roman world," Shamir told LiveScience in a telephone interview. "They were very humble, they didn't want to wear colorful textiles, they wanted to use very simple textiles."
The owners of the clothing likely were not poor, as only one of the textiles had a patch on it."This is very, very, important," Shamir said. "Patching is connected with [the] economic situation of the site."
Shamir pointed out that textiles found at sites where people were under stress, such as at the Cave of Letters, which was used in a revolt against the Romans, were often patched. On the other hand "if the site is in a very good economic situation, if it is a very rich site, the textiles will not be patched," she said. With Qumran, "I think [economically] they were in the middle, but I'm sure they were not poor."
Robert Cargill, a professor at the University of Iowa, has written extensively about Qumran and has developed a virtual model of it. He said that archaeological evidence from the site, including coins and glassware, also suggests the inhabitants were not poor..."
New Find Sheds Light on Ancient Site in Jerusalem
|2:41:56 PM, Wednesday, November 23, 2011|
"JERUSALEM (AP) — Newly found coins underneath Jerusalem's Western Wall could change the accepted belief about the construction of one of the world's most sacred sites two millennia ago, Israeli archaeologists said Wednesday.
The man usually credited with building the compound known to Jews as the Temple Mount and to Muslims as the Noble Sanctuary is Herod, a Jewish ruler who died in 4 B.C. Herod's monumental compound replaced and expanded a much older Jewish temple complex on the same site.
But archaeologists with the Israel Antiquities Authority now say diggers have found coins underneath the massive foundation stones of the compound's Western Wall that were stamped by a Roman proconsul 20 years after Herod's death. That indicates that Herod did not build the wall — part of which is venerated as Judaism's holiest prayer site — and that construction was not close to being complete when he died.
"The find changes the way we see the construction, and shows it lasted for longer than we originally thought," said the dig's co-director, Eli Shukron.
The four bronze coins were stamped around 17 A.D. by the Roman official Valerius Gratus. He preceded Pontius Pilate of the New Testament story as Rome's representative in Jerusalem, according to Ronny Reich of Haifa University, one of the two archaeologists in charge of the dig.
The coins were found inside a ritual bath that predated construction of the renovated Temple Mount complex and which was filled in to support the new walls, Reich said.
They show that construction of the Western Wall had not even begun at the time of Herod's death. Instead, it was likely completed only generations later by one of his descendants.
The coins confirm a contemporary account by Josephus Flavius, a Jewish general who became a Roman historian. Writing after a Jewish revolt against Rome and the destruction of the Temple by legionnaires in 70 A.D., he recounted that work on the Temple Mount had been completed only by King Agrippa II, Herod's great-grandson, two decades before the entire compound was destroyed.
Scholars have long been familiar with Josephus' account, but the find is nonetheless important because it offers the "first clear-cut archaeological evidence that part of the enclosure wall was not built by Herod," said archaeologist Aren Maeir of Bar-Ilan University, who was not involved in the dig.
Josephus also wrote that the end of construction left 18,000 workmen unemployed in Jerusalem. Some historians have linked this to discontent that eventually erupted in the Jewish revolt.
The compound, controlled since 1967 by Israel, now houses the Al-Aqsa Mosque and the golden-capped Muslim shrine known as the Dome of the Rock. The fact that the compound is holy both to Jews and Muslims makes it one of the world's most sensitive religious sites.
The dig in which the coins were discovered cleared a Roman-era drainage tunnel that begins at the biblical Pool of Siloam, one of the city's original water sources, and terminates with a climb up a ladder out onto a 2,000-year-old street inside Jerusalem's Old City. The tunnel runs by the foundation stones of the compound's western wall, where the coins were found.
The drainage tunnel was excavated as part of the dig at the City of David, which is perhaps Israel's richest archaeological excavation and its most contentious.
The dig is being carried out inside the Palestinian neighborhood of Silwan, and is funded by a group associated with the Israeli settlement movement that opposes any division of the city as part of a future peace deal.
The excavation of the tunnel has also yielded a Roman sword, oil lamps, pots and coins that scholars believe are likely debris from an attempt by Jewish rebels to hide in the underground passage as they fled from the Roman soldiers."
Russia's Stranded Mars Probe Sends Signal to Earth
|2:37:07 PM, Wednesday, November 23, 2011|
"Engineers fought desperately on Wednesday to save Russia's Phobos-Grunt spacecraft after the Martian probe sent "a first sign of life" more than two weeks after being stranded in orbit.
After days of frustrating silence, contact with the probe was made on Tuesday at 2025 GMT at a European Space Agency ground station in Perth, Western Australia, the Paris-based ESA said.
"ESA teams are working closely with engineers in Russia to determine how best to maintain communication with the spacecraft," it said.
A spokesman at European Space Operations Centre (ESOC) in Darmstadt, Germany, told AFP: "We sent an instruction to (the probe) to switch on its transmitter and the probe sent us telemetric data.
"However, we do not have all the details and we are not very sure of what we received. It's a first sign of life," he said.
The probe is in a "very low, very unfavourable orbit (that) is difficult to identify accurately," the spokesman added.
The task is being complicated by very narrow windows for communication "of between five and 10 minutes," he explained.
The five-billion-ruble ($165-million) mission is one of the most ambitious in the history of Martian exploration.
It is designed to travel to the moon of Phobos, scoop up soil and return the sample to Earth by 2014.
But mission control lost radio contact with the craft hours after launch on November 8, leaving engineers bewildered as to where it was. On Tuesday, Russia's space agency had said it saw "little chance" of saving the 13.5-tonne vessel.
In Moscow, the Russian space agency Roskosmos confirmed the ESA report.
It said the Perth station had received a radio signal from Phobos-Grunt during a scheduled monitoring period and European and Russian were "appraising the situation."
The probe blasted off successfully from the Baikonur cosmodrome but did not manage to leave its Earth orbit as planned.
Motors failed to fire twice to steer it on a course for Mars, and it is still carrying the fuel that would have been used in this manoeuvre.
But before losing control of the probe, the Russians sent out instructions for it to deploy its solar panels, an ESA official said.
"Initially, it was thought that the spacecraft would die after three days when its battery ran out.
"But the solar panels played a crucial role yesterday, enabling the ground station in Perth to make contact," the source said.
Perth is the sole means of communicating with Phobos-Grunt as it is the only listening post in a part of the Earth that is in daylight when the probe passes overhead, the official explained.
Exposure to the sunlight provides electricity to the spacecraft, enabling to briefly talk to the ground. But it loses power when it moves over ground stations in parts of the globe that are in night.
Phobos-Grunt is also carrying a Chinese satellite, Yinghuo-1, which was to go into orbit around Mars in a landmark space cooperation between Moscow and Beijing.
Orbiting Mars at just under 10,000 kilometres (6,000 miles) distance, Phobos is believed to be the closest moon to any planet in the Solar System. It has long intrigued scientists, who believe it holds secrets about the origins of the planets."
Olympus BioScapes Competition 2011 Winners: Incredible Microscopic Images Of The Natural World
|6:38:39 PM, Sunday, November 20, 2011|
"The Olympus BioScapes competition has produced some of the world's most stunning microscopic digital images and videos of life science.
Now in its eighth year running, the winning entry is a photograph by Charles Krebs of Issaquah, Washington showing an underwater Rotifer Floscularia that relies on rapidly beating cilia to bring food-laden water in so it can feed.
From live green brain coral captured underwater to stink bug eggs snapped in Greece, you'll see some breathtaking photos of nature at its most beautiful.
Other images not to be missed include the reproductive system of a fruit fly and the golden chloroplasts in a living diatom..."
Scientists Create Light from Vacuum
|5:38:31 PM, Sunday, November 20, 2011|
"Scientists at Chalmers University of Technology have succeeded in creating light from vacuum - observing an effect first predicted over 40 years ago. The results will be published tomorrow (Wednesday) in the journal Nature. In an innovative experiment, the scientists have managed to capture some of the photons that are constantly appearing and disappearing in the vacuum.
The experiment is based on one of the most counterintuitive, yet, one of the most important principles in quantum mechanics: that vacuum is by no means empty nothingness. In fact, the vacuum is full of various particles that are continuously fluctuating in and out of existence. They appear, exist for a brief moment and then disappear again. Since their existence is so fleeting, they are usually referred to as virtual particles.
Chalmers scientist, Christopher Wilson and his co-workers have succeeded in getting photons to leave their virtual state and become real photons, i.e. measurable light. The physicist Moore predicted way back in 1970 that this should happen if the virtual photons are allowed to bounce off a mirror that is moving at a speed that is almost as high as the speed of light. The phenomenon, known as the dynamical Casimir effect, has now been observed for the first time in a brilliant experiment conducted by the Chalmers scientists.
"Since it's not possible to get a mirror to move fast enough, we've developed another method for achieving the same effect," explains Per Delsing, Professor of Experimental Physics at Chalmers. "Instead of varying the physical distance to a mirror, we've varied the electrical distance to an electrical short circuit that acts as a mirror for microwaves.
The "mirror" consists of a quantum electronic component referred to as a SQUID (Superconducting quantum interference device), which is extremely sensitive to magnetic fields. By changing the direction of the magnetic field several billions of times a second the scientists were able to make the "mirror" vibrate at a speed of up to 25 percent of the speed of light.
"The result was that photons appeared in pairs from the vacuum, which we were able to measure in the form of microwave radiation," says Per Delsing. "We were also able to establish that the radiation had precisely the same properties that quantum theory says it should have when photons appear in pairs in this way."
What happens during the experiment is that the "mirror" transfers some of its kinetic energy to virtual photons, which helps them to materialise. According to quantum mechanics, there are many different types of virtual particles in vacuum, as mentioned earlier. Goran Johansson, Associate Professor of Theoretical Physics, explains that the reason why photons appear in the experiment is that they lack mass.
"Relatively little energy is therefore required in order to excite them out of their virtual state. In principle, one could also create other particles from vacuum, such as electrons or protons, but that would require a lot more energy."
The scientists find the photons that appear in pairs in the experiment interesting to study in closer detail. They can perhaps be of use in the research field of quantum information, which includes the development of quantum computers.
However, the main value of the experiment is that it increases our understanding of basic physical concepts, such as vacuum fluctuations - the constant appearance and disappearance of virtual particles in vacuum. It is believed that vacuum fluctuations may have a connection with "dark energy" which drives the accelerated expansion of the universe. The discovery of this acceleration was recognized this year with the awarding of the Nobel Prize in Physics."
NASA Probe Data Show Evidence of Liquid Water on Icy Europa
|5:32:59 PM, Wednesday, November 16, 2011|
â€śData from a NASA planetary mission have provided scientists evidence of what appears to be a body of liquid water, equal in volume to the North American Great Lakes, beneath the icy surface of Jupiter's moon, Europa. The data suggest there is significant exchange between Europa's icy shell and the ocean beneath. This information could bolster arguments that Europa's global subsurface ocean represents a potential habitat for life elsewhere in our solar system. The findings are published in the scientific journal Nature. "The data opens up some compelling possibilities," said Mary Voytek, director of NASA's Astrobiology Program at agency headquarters in Washington. "However, scientists worldwide will want to take a close look at this analysis and review the data before we can fully appreciate the implication of these results." NASA's Galileo spacecraft, launched by the space shuttle Atlantis in 1989 to Jupiter, produced numerous discoveries and provided scientists decades of data to analyze. Galileo studied Jupiter, which is the most massive planet in the solar system, and some of its many moons. One of the most significant discoveries was the inference of a global salt water ocean below the surface of Europa. This ocean is deep enough to cover the whole surface of Europa and contains more liquid water than all of Earth's oceans combined. However, being far from the sun, the ocean surface is completely frozen. Most scientists think this ice crust is tens of miles thick. "One opinion in the scientific community has been if the ice shell is thick, that's bad for biology. That might mean the surface isn't communicating with the underlying ocean," said Britney Schmidt, lead author of the paper and postdoctoral fellow at the Institute for Geophysics, University of Texas at Austin. "Now, we see evidence that it's a thick ice shell that can mix vigorously and new evidence for giant shallow lakes. That could make Europa and its ocean more habitable." Schmidt and her team focused on Galileo images of two roughly circular, bumpy features on Europa's surface called chaos terrains. Based on similar processes seen on Earth -- on ice shelves and under glaciers overlaying volcanoes -- they developed a four-step model to explain how the features form. The model resolves several conflicting observations. Some seemed to suggest the ice shell is thick. Others suggest it is thin. This recent analysis shows the chaos features on Europa's surface may be formed by mechanisms that involve significant exchange between the icy shell and the underlying lake. This provides a mechanism or model for transferring nutrients and energy between the surface and the vast global ocean already inferred to exist below the thick ice shell. This is thought to increase the potential for life there. The study authors have good reason to believe their model is correct, based on observations of Europa from Galileo and of Earth. Still, because the inferred lakes are several miles below the surface, the only true confirmation of their presence would come from a future spacecraft mission designed to probe the ice shell. Such a mission was rated as the second highest priority flagship mission by the National Research Council's recent Planetary Science Decadal Survey and is being studied by NASA. "This new understanding of processes on Europa would not have been possible without the foundation of the last 20 years of observations over Earth's ice sheets and floating ice shelves," said Don Blankenship, a co-author and senior research scientist at the Institute for Geophysics, where he leads airborne radar studies of the planet's ice sheets. Galileo was the first spacecraft to directly measure Jupiter's atmosphere with a probe and conduct long-term observations of the Jovian system. The probe was the first to fly by an asteroid and discover the moon of an asteroid. NASA extended the mission three times to take advantage of Galileo's unique science capabilities, and it was put on a collision course into Jupiter's atmosphere in September 2003 to eliminate any chance of impacting Europa. The Galileo mission was managed by NASA's Jet Propulsion Laboratory in Pasadena, Calif., for the agency's Science Mission Directorate.â€ť
Transporter 5: Solving an Ancient Mystery of the Cell
|9:04:27 PM, Tuesday, November 15, 2011|
â€śThe discovery by scientists in Cambridge and Alberta of a fifth adaptor protein â€“ a tiny and vital component of many cells â€“will lay the foundations for a greater understanding of genetic disorders.
The people who work there call it the Titanic. The Cambridge Institute for Medical Research, a shiny building with funnel-like air vents on the Addenbrookeâ€™s complex, is the workplace of around 250 scientists, many of them internationally acclaimed in their fields. Its 40 research groups are dedicated to advancing the basic and clinical science that is needed to understand the molecular mechanisms of disease. It is in these laboratories that some of the foundational research takes place that will pave the way for the development of drugs and therapies that will save lives in the future.
Earlier this year one of these groups â€“ a team of seven scientists led by eminent cell biologist Professor Margaret Robinson â€“ made a discovery that will lead to some of the key information contained in cell biology textbooks being revised. Working with colleagues at the University of Alberta in Canada, the team showed that the cells of all eukaryotes (a term used to describe the cell structure of animals, plants and fungi) contain five adaptor protein complexes (APs). This finding confounds existing assumptions that only four APs are present in cells â€“ and will help scientists learn more about, and ultimately treat, certain genetic disorders.
Scientists have known about the existence of APs â€“ which are vital to the functions of cells â€“ ever since the late 1970s. Four APs were identified by researchers in the space of some 20 years. â€śAs recently as 2004 I was quoted in the scientific literature stating categorically that there were no more than four APs,â€ť says Professor Robinson. â€śIt just goes to show that you canâ€™t be too certain that youâ€™ve found everything there is to find. And even more importantly it illustrates just how vital it is to carry out fundamental research, to provide the knowledge needed to feed into the translational research that could ultimately lead to cures for diseases.â€ť
Cells are often described as the building blocks of life. As every school child is taught, cells have a nucleus, a surrounding membrane and cytoplasm. The intricate workings of the cell, however, are much more complex and represent a fascinating puzzle for biologists. Cells are full of compartments, visible only through the most powerful microscopes. These compartments do not exist in isolation but communicate with each other â€“ for example, to send newly-made molecules from the place where they are manufactured to the place where they need to be in order to function.
Tiny spherical vesicles transport proteins and other molecules around the cell in a process that scientists call trafficking. But in order for the different compartments not to get mixed up, the cell needs to put some molecules into vesicles as cargo to be delivered to a new compartment, while leaving others behind. The machinery that selects which molecules will go into the vesicles includes the adaptor proteins. The word adaptor is used to describe their ability to connect two different types of molecules together: the cargo and the structural proteins that physically form the vesicle.
The way in which adaptor proteins pick up molecules from compartments can be likened to diners in a sushi bar, picking up dishes of food from a passing conveyor belt avoiding items they dislike and opting for those they desire. â€śAPs have different ways of recognising molecules. Itâ€™s a process that we are only just beginning to understand, but this fundamental research could impact on the study of diseases where certain molecules fail to get trafficked correctly,â€ť says Dr. Jennifer Hirst, who is a senior researcher in the Robinson lab and has discovered and characterised a number of new adaptorsâ€¦â€ť
Mimicking the Brain -- In Silicon: New Computer Chip Models How Neurons Communicate With Each Other at Synapses
|8:58:20 PM, Tuesday, November 15, 2011|
â€śFor decades, scientists have dreamed of building computer systems that could replicate the human brain's talent for learning new tasks.
MIT researchers have now taken a major step toward that goal by designing a computer chip that mimics how the brain's neurons adapt in response to new information. This phenomenon, known as plasticity, is believed to underlie many brain functions, including learning and memory.
With about 400 transistors, the silicon chip can simulate the activity of a single brain synapse -- a connection between two neurons that allows information to flow from one to the other. The researchers anticipate this chip will help neuroscientists learn much more about how the brain works, and could also be used in neural prosthetic devices such as artificial retinas, says Chi-Sang Poon, a principal research scientist in the Harvard-MIT Division of Health Sciences and Technology.
Poon is the senior author of a paper describing the chip in the Proceedings of the National Academy of Sciences the week of Nov. 14. Guy Rachmuth, a former postdoc in Poon's lab, is lead author of the paper. Other authors are Mark Bear, the Picower Professor of Neuroscience at MIT, and Harel Shouval of the University of Texas Medical School.
There are about 100 billion neurons in the brain, each of which forms synapses with many other neurons. A synapse is the gap between two neurons (known as the presynaptic and postsynaptic neurons). The presynaptic neuron releases neurotransmitters, such as glutamate and GABA, which bind to receptors on the postsynaptic cell membrane, activating ion channels. Opening and closing those channels changes the cell's electrical potential. If the potential changes dramatically enough, the cell fires an electrical impulse called an action potential.
All of this synaptic activity depends on the ion channels, which control the flow of charged atoms such as sodium, potassium and calcium. Those channels are also key to two processes known as long-term potentiation (LTP) and long-term depression (LTD), which strengthen and weaken synapses, respectively.
The MIT researchers designed their computer chip so that the transistors could mimic the activity of different ion channels. While most chips operate in a binary, on/off mode, current flows through the transistors on the new brain chip in analog, not digital, fashion. A gradient of electrical potential drives current to flow through the transistors just as ions flow through ion channels in a cell.
"We can tweak the parameters of the circuit to match specific ion channels," Poon says. "We now have a way to capture each and every ionic process that's going on in a neuron."
Previously, researchers had built circuits that could simulate the firing of an action potential, but not all of the circumstances that produce the potentials. "If you really want to mimic brain function realistically, you have to do more than just spiking. You have to capture the intracellular processes that are ion channel-based," Poon says.
The new chip represents a "significant advance in the efforts to incorporate what we know about the biology of neurons and synaptic plasticity onto CMOS [complementary metal-oxide-semiconductor] chips," says Dean Buonomano, a professor of neurobiology at the University of California at Los Angeles, adding that "the level of biological realism is impressive.
The MIT researchers plan to use their chip to build systems to model specific neural functions, such as the visual processing system. Such systems could be much faster than digital computers. Even on high-capacity computer systems, it takes hours or days to simulate a simple brain circuit. With the analog chip system, the simulation is even faster than the biological system itself.
Another potential application is building chips that can interface with biological systems. This could be useful in enabling communication between neural prosthetic devices such as artificial retinas and the brain. Further down the road, these chips could also become building blocks for artificial intelligence devices, Poon saysâ€¦.â€ť
HOME Older Posts »