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Hi~~~ 周一的科技又跟大家见面了，
新的一个月，一个学期开始了，
希望大家一如既往的在努力，一如既往的支持阅读小分队！！
加油！！
今天的文章都不长，time2，3为一篇文章，time4，5为一篇文章，time6，time7各为一篇，除了第一篇外都是关于天体、宇宙类的，希望大家enjoy~
Part I：Speaker
[Rephrase 1]
Different Placebos Can Have Different Effects
[Dialog, 1:20]
[transcript hided]
When it comes to providing pain relief, expectations can be a powerful prescription. That’s part of the theory behind the placebo effect, in which people often report feeling better—even after a sugar pill or sham procedure—simply because they expect improvement.
Now a study finds that there may be levels of placebo effect.
Forty-five healthy volunteers had a heating electrode placed on their skin to cause discomfort. Over multiple sessions, they were either given nothing, or Tylenol, or traditional acupuncture or electro-acupuncture, in which the needles carry a slight current.
Painkillers should let them tolerate the heat longer. The hitch was that the Tylenol and conventional acupuncture were fakes.
The subjects were later interviewed about their expectations. And their feelings about each treatment largely determined its effect. Those who thought the acupuncture would work were more likely to report pain reduction in both the real and fake acu-treatments. The findings are in the journal PLOS ONE.
They suggest a variable placebo effect, one that may depend on whether you swallow that sugar pill with a grain of salt.
Source: Scientific American
http://www.scientificamerican.com/podcast/episode.cfm?id=different-placebos-can-have-differe-13-08-27
Part II：Speed
Babies learn words before birth
Brain responses suggest infants can distinguish distinct sounds from altered versions
[TIME 2]
Parents-to-be better watch their language. Babies can hear specific words in the womb and remember them in the days after birth, a new study reports. The results add to the understanding of how the early acoustical environment shapes the developing brain.
Earlier studies have found that fetuses can hear and learn certain sounds. Nursery rhymes, vowel sounds and mothers’ voices can all influence a developing baby. But the new study, published August 26 in the Proceedings of the National Academy of Sciences, shows that a fetus can detect and remember discrete words, says study coauthor Eino Partanen of the University of Helsinki. “The fetal learning capabilities are much more specific than we thought,” he says.
Partanen and colleagues used a fake word, tatata, to test whether a particular word can worm its way into the fetal brain. Five to seven times a week during their third trimester, 17 pregnant Finnish women were instructed to blast a recording of a woman saying the word in two bursts of four minutes. The pregnant women were instructed to turn the volume up so loud that a conversation would be difficult, but not so loud that it hurt. Most of the recording was the same delivery of tatata, but every so often, there was a curveball. The pitch in the middle syllable would change, something that rarely happens in spoken Finnish.
(words:227)
[TIME 3]
Five days after their birth, babies once again heard the recordings. Electrodes attached to the babies’ heads allowed Partanen and his colleagues to look for a specific sign of recognition: An outsized neural jolt, called a mismatch response, tells the brain to pay attention because something is different. This response indicates a level of familiarity, Partanen says. Adults acquire similar neural reactions as they learn a new language, for instance.
When the recording reached the altered version of tatata, babies who had been exposed to the recordings in utero showed this mismatch response, while the 16 babies who hadn’t heard the recordings didn’t, the team found. These results suggest that babies could learn and remember the normal version of tatata.
It’s not clear how long these word memories last. In the study, the fetuses last heard the recording five days before birth, but the memory could be older than that.
The study goes beyond earlier work, much of which relied on indirect behavioral changes such as sucking on a pacifier or turning the head, and instead reveals effects in the brain, says psychologist Christine Moon of Pacific Lutheran University in Tacoma, Wash. “We’ve had quite a bit of research on behavior and not so much on the brain,” she says.
The finding has implications for early intervention in kids who might be at risk of language problems, which can accompany certain kinds of dyslexia, says Partanen. Carefully designed words or features of speech played during pregnancy might prove beneficial, he says.
(words:251)
Source: Science News
http://www.sciencenews.org/view/generic/id/352781/description/Babies_learn_words_before_birth
The sun's older twin, 250 light-years away
Almost twice as ancient, star gives glimpse of sun's future
[TIME 4]
When the sun enters its twilight years, chances are it will look just like HIP 102152.
In terms of mass, temperature and chemical composition, the star HIP 102152 is the closest match to the sun ever found, astronomers announced August 28 at a press conference. But it’s also almost 4 billion years older, providing a tantalizing glimpse of what might happen to our 4.6-billion-year-old sun as it ages.
“Work with solar twins is helping us contextualize the sun as a star,” says Gustavo Porto de Mello, an astronomer at the Federal University of Rio de Janeiro who was not involved in the research. “This is another step toward finding stars that represent the sun at various stages of evolution.”
HIP 102152 has given the researchers insight on lithium, an element that exists in high amounts in some stars but is virtually absent in the sun. Some astronomers have wondered whether that makes the sun an outlier, Porto de Mello says. But the researchers found that HIP 102152 contains even less lithium than the sun, while a previously identified younger solar twin named 18 Scorpii has more. The findings suggest that the hot, churning interiors of sunlike stars gradually burn through lithium as the stars age. “This might be trying to tell us about the inner workings of the sun,” Porto de Mello says.
(words:223)
[TIME 5]
Like the sun, HIP 102152 has relatively low amounts of iron, magnesium and silicon, elements that tend to make up the bulk of the mass of rocky planets such as Earth. That could be a sign that the newly discovered star hosts planets, says study coauthor Iván Ramírez from the University of Texas at Austin. The researchers are using the La Silla 3.6-meter telescope in Chile to find out. So far they have ruled out the existence of Jupiter-mass planets, but small rocky ones are still possible.
Finding stars nearly identical to the sun is a difficult task because stars tend to have quirks and anomalies. Plus, it is time consuming and expensive to precisely measure a star’s properties.
An international team of astronomers has been hunting solar twins since 2006, when it began picking out promising candidates from a sky survey. One was HIP 102152, which is located about 250 light-years away in the constellation Capricornus.
Now the researchers have performed a detailed analysis with the European Southern Observatory’s Very Large Telescope in Chile, which will be published in Astronomical Journal Letters. HIP 102152 is 97 percent as massive as the sun, 54 degrees Celsius cooler and has very similar abundances of more than 20 chemical elements. “It’s about as dead-on a twin as you could reasonably hope to find,” says David Soderblom, an astronomer at the Space Telescope Science Institute in Baltimore who was not on the research team.
At 8.2 billion years old, HIP 102152 is the oldest solar twin ever found. In less than 2 billion years, the star will run out of hydrogen in its core and start ballooning to hundreds of times its current size. When that happens to our star, the sun will fry Earth and probably engulf it.
(words:296)
Source: Science NEWs
http://www.sciencenews.org/view/generic/id/352866/description/The_suns_older_twin_250_light-years_away
'Trojan' Asteroids in Far Reaches of Solar System More Common Than Previously Thought
[TIME 6]
Trojans are asteroids that share the orbit of a planet, occupying stable positions known as Lagrangian points. Astronomers considered their presence at Uranus unlikely because the gravitational pull of larger neighbouring planets would destabilize and expel any Uranian Trojans over the age of the Solar System.
To determine how the 60 kilometre-wide ball of rock and ice ended up sharing an orbit with Uranus the astronomers created a simulation of the Solar System and its co-orbital objects, including Trojans.
"Surprisingly, our model predicts that at any given time three per cent of scattered objects between Jupiter and Neptune should be co-orbitals of Uranus or Neptune," says Mike Alexandersen, lead author of the study to be published tomorrow in the journalScience. This percentage had never before been computed, and is much higher than previous estimates.
Several temporary Trojans and co-orbitals have been discovered in the Solar System during the past decade. QF99 is one of those temporary objects, only recently (within the last few hundred thousand years) ensnared by Uranus and set to escape the planet's gravitational pull in about a million years.
"This tells us something about the current evolution of the Solar System," says Alexandersen. "By studying the process by which Trojans become temporarily captured, one can better understand how objects migrate into the planetary region of the Solar System."
(words:221)
Source: Science Daily
http://www.sciencedaily.com/releases/2013/08/130829145214.htm
Part III： Obstacle
Ultracold Big Bang Experiment Successfully Simulates Evolution of Early Universe
[TIME 7]
"This is the first time an experiment like this has simulated the evolution of structure in the early universe," said Cheng Chin, professor in physics. Chin and his associates reported their feat in the Aug. 1 edition of Science Express, and it will appear soon in the print edition of Science.
Chin pursued the project with lead author Chen-Lung Hung, PhD'11, now at the California Institute of Technology, and Victor Gurarie of the University of Colorado, Boulder. Their goal was to harness ultracold atoms for simulations of the big bang to better understand how structure evolved in the infant universe.
The cosmic microwave background is the echo of the big bang. Extensive measurements of the CMB have come from the orbiting Cosmic Background Explorer in the 1990s, and later by the Wilkinson Microwave Anisotropy Probe and various ground-based observatories, including the UChicago-led South Pole Telescope collaboration. These tools have provided cosmologists with a snapshot of how the universe appeared approximately 380,000 years following the Big Bang, which marked the beginning of the universe.
It turns out that under certain conditions, a cloud of atoms chilled to a billionth of a degree above absolute zero (-459.67 degrees Fahrenheit) in a vacuum chamber displays phenomena similar to those that unfolded following the big bang, Hung said.
"At this ultracold temperature, atoms get excited collectively. They act as if they are sound waves in air," he said. The dense package of matter and radiation that existed in the very early universe generated similar sound-wave excitations, as revealed by COBE, WMAP and the other experiments.
The synchronized generation of sound waves correlates with cosmologists' speculations about inflation in the early universe. "Inflation set out the initial conditions for the early universe to create similar sound waves in the cosmic fluid formed by matter and radiation," Hung said.
Big bang's rippling echo
The sudden expansion of the universe during its inflationary period created ripples in space-time in the echo of the big bang. One can think of the big bang, in oversimplified terms, as an explosion that generated sound, Chin said. The sound waves began interfering with each other, creating complicated patterns. "That's the origin of complexity we see in the universe," he said.
These excitations are called Sakharov acoustic oscillations, named for Russian physicist Andrei Sakharov, who described the phenomenon in the 1960s. To produce Sakharov oscillations, Chin's team chilled a flat, smooth cloud of 10,000 or so cesium atoms to a billionth of a degree above absolute zero, creating an exotic state of matter known as a two-dimensional atomic superfluid.
Then they initiated a quenching process that controlled the strength of the interaction between the atoms of the cloud. They found that by suddenly making the interactions weaker or stronger, they could generate Sakharov oscillations.
The universe simulated in Chin's laboratory measured no more than 70 microns in diameter, approximately the diameter as a human hair. "It turns out the same kind of physics can happen on vastly different length scales," Chin explained. "That's the power of physics."
The goal is to better understand the cosmic evolution of a baby universe, the one that existed shortly after the big bang. It was much smaller then than it is today, having reached a diameter of only a hundred thousand light years by the time it had left the CMB pattern that cosmologists observe on the sky today.
In the end, what matters is not the absolute size of the simulated or the real universes, but their size ratios to the characteristic length scales governing the physics of Sakharov oscillations. "Here, of course, we are pushing this analogy to the extreme," Chin said.
380,000 years versus 10 milliseconds
"It took the whole universe about 380,000 years to evolve into the CMB spectrum we're looking at now," Chin said. But the physicists were able to reproduce much the same pattern in approximately 10 milliseconds in their experiment. "That suggests why the simulation based on cold atoms can be a powerful tool," Chin said.
None of the Science co-authors are cosmologists, but they consulted several in the process of developing their experiment and interpreting its results. The co-authors especially drew upon the expertise of UChicago's Wayne Hu, John Carlstrom and Michael Turner, and of Stanford University's Chao-Lin Kuo.
Hung noted that Sakharov oscillations serve as an excellent tool for probing the properties of cosmic fluid in the early universe. "We are looking at a two-dimensional superfluid, which itself is a very interesting object. We actually plan to use these Sakharov oscillations to study the property of this two-dimensional superfluid at different initial conditions to get more information."
The research team varied the conditions that prevailed early in the history of the expansion of their simulated universes by quickly changing how strongly their ultracold atoms interacted, generating ripples. "These ripples then propagate and create many fluctuations," Hung said. He and his co-authors then examined the ringing of those fluctuations.
Today's CMB maps show a snapshot of how the universe appeared at a moment in time long ago. "From CMB, we don't really see what happened before that moment, nor do we see what happened after that," Chin said. But, Hung noted, "In our simulation we can actually monitor the entire evolution of the Sakharov oscillations."
Chin and Hung are interested in continuing this experimental direction with ultracold atoms, branching into a variety of other types of physics, including the simulation of galaxy formation or even the dynamics of black holes.
"We can potentially use atoms to simulate and better understand many interesting phenomena in nature," Chin said. "Atoms to us can be anything you want them to be."
(words:940)
Source: Science Daily
http://www.sciencedaily.com/releases/2013/08/130829092845.htm
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发表于 2013-9-2 23:26:03
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