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又是新的一期了
大家跟上节奏没有啊？！！
反正我是没有跟上~~~噼里啪啦！！示众暴打！！o(╯□╰)o
新的一期大家继续努力！ 坚持就是胜利~~~~
好了，上作业~~ enjoy！`(*∩_∩*)′
Part I：Speaker
[Rephrase 1] Ancient Europeans Added Zing To Meals
[Dialog, 1:13]
[transcript hided]
Spicy, tangy, sharp, complex—spices add vibrancy to modern meals. Prehistoric cuisine, however, was thought of as, well, bland, based on scientists’ focusing on the energy value of our ancestors’ food: you catch the caribou, you cook the caribou, you eat the caribou. But bland is now a bygone view. Because researchers have found evidence in prehistoric pots that add spice, literally, to that ancient world. The study is in the journal PLoS ONE. [Hayley Saul et al, Phytoliths in Pottery Reveal the Use of Spice in European Prehistoric Cuisine] Archaeologists analyzed the remains of cooking pots at three sites in Northern Europe from more than 6000 years ago, during the transition from hunting and gathering to agriculture. They found what are called phytoliths. These are mineralized bits of plant residue. And some of the phytoliths closely resemble modern-day garlic mustard seeds. Such seeds have little nutritional value, but lend a sharp peppery bite to foods. Researchers had previously identified aromatic substances in really leftover food—dating back around 5,000 years. Anything earlier than that, though, was tough to discern. But these phytoliths have now provided what the researchers say is the earliest known use of spice in cuisine. Bon appetite! Sources:http://www.scientificamerican.com/podcast/episode.cfm?id=ancient-europeans-added-zing-to-mea-13-08-23
5 Ways To Protect YourBrain, And Boost Your Career
【 Time2 】
Not so long ago, conventional wisdom among neuroscientists held that the human brain was doomed to deteriorate with the passage of time, and there wasn't much anyone could do about it.
Instead, a raft of recent studies, aided by brain-imaging technology, all point to a much different conclusion: Our grey matter can keep on regenerating throughout life, producing new active cells all the time. "Your brain is a living and constantly developing dense forest with billions of neurons and synapses, " says Alvaro Fernandez, founderand CEO of market research firm SharpBrains.
The emerging science of neuro plasticity, which studies how our brains change and adapt, is revealing that, as with muscles,it's a case of "use it or lose it, " he adds. "Once new neurons appear in your brain, where they stay and how long they survive depends on how you use them."
Fernandez is co-author of a book called The Sharp Brains Guide to Brain Fitness that boils down the current explosion of new research in this area to specific advice on what to do now to guard against Alzheimer's and other forms of cognitive impairment later on.
By a lucky coincidence, there's plenty ofoverlap between what's good for your brain and what could turbo-charge your career. Consider these five tips: 1. Never stop learning. The latest research shows conclusively that, the better educated a person is, the less likely sheis to suffer from age-related decline. "Highly educated people are likely to have mentally stimulating jobs, " Fernandez notes, and that fosters the birth of new neurons. If you get into the habit of learning new skills throughout your career -- which also happens to make you more marketable and promotable -- your brain will thank you later.
2. Immerse yourself in another culture. In particular, learn another language. As U.S. business (especially marketing) becomes ever more bilingual, Spanish would be smart -- but, for the ultimate brain workout, pick Russian, Mandarin, or Arabic, whose different alphabets make them that much more challenging.
If you can, volunteer for overseas gigs, too.Not only do these make your resume stand out from the crowd, but"exploring and adjusting to new locations forces you to pay more attention to your environment" than staying home, Fernandez notes. Navigating an unfamiliar culture, even for a short time, is like calisthenics for your brain. （words：392）
【 Time3 】
3. Seek out tough "stretch"assignments. "The goal is to be exposed to novelty and increasing levels of challenge, so the task never becomes too easy or routine, " Fernandezwrites, adding that this means "expending effort and getting out of your comfort zone." Variety is as important as challenge, several new studies show:"Excessive specialization is not the best strategy for maintaining long-term brain health. A bond trader may thus want to try an artistic activity, to stimulate brain cells that he or she rarely uses otherwise."
4. Manage stress. "Excessive stress, no matter whether induced by external events or by your own thoughts, actually kills neurons and prevents the formation of new ones, " Fernandez notes.Obviously, you don't want that. The Sharp Brains Guide to Brain Fitness goesinto detail on how physical exercise, meditation, and even having a good laugh help to protect your brain from the ravages of too much pressure, while heading off job burn out too. Taking a real vacation once in a while is also a proven stress fighter.
5. Have lots of friends. Not only is a vast and varied network of pals a huge advantage when you want to change jobs (or hirethe right person), but it turns out that "social engagement contributes to brain health, " Fernandez writes. New research shows that regularly interacting with a wide range of other people contributes to "both short-term performance boosts and the build up of cognitive reserve."
Is there an ideal number of friends? The human cerebral cortex, it seems, can efficiently process only a limited number of relationships, and that number (known to neuroscientists as Dunbar's number,after the researcher who found it) is 150. In an interesting aside, Fernandeznotes that, although some people have thousands of Facebook friends, "the typical number is around 120, which corresponds roughly to Dunbar's number --that is, the number of friends and acquaintances people generally have in reallife. （words：324） http://xue.youdao.com/biarticle.a?articleId=6879462389697643237&date=2013-08-24&position=read-history&channelType=public
Top 10 Myths About Animals
【 Time4 】
With around 8.7 million animal species gracing our planet, it’s no wonder that we have some facts about animals totally wrong.Some animals and their behavior remain mysterious to scientists and it’s only through long term research and observation that they’ve been able to bust a number of animal myths. Here’s a list of well-known but utterly false facts about the fury, scaly and slimy creatures that grace our planet. 10. Myth: Bats are blind.
Often associated with darkness, witches and black magic, bats have a lot of mythology and misconceptions surrounding them,making them seem like foreboding creatures of the night. Although people often think bats are blind due to their only hunting at night, the fact is that all species of bats can see, although their vision is poorly developed. To compensate they have excellent senses of smell and hearing, and are able to use echo-location and sonar abilities to navigate and hunt at night. Their sonar abilities are so exceptional that they’re often better than military-grade sonar, which is amazing for such small animals.
9. Myth: Elephants are the only animals that cannot jump. It’s true, elephants can’t jump – if by jumping we mean the state at which an animal propels itself off the ground by its own force, with all feet off the ground at the same time – but they’re definitely not the only ones. A few other animals that can’t jump are the sloth, hippo,rhino, giraffe, rockhopper penguin, and countless others. Could you imagine ahippo gliding gracefully through the air? Perhaps only if you’re into Disney cartoons.
8. Myth: A goldfish has a 3-second memory. If you’ve ever been told that you have the memory of a goldfish, you’ll understand why this myth is so ingrained insociety. The actual memory span of goldfish is at least three months, and some researchers have managed to prove that goldfish can remember what they have been taught up to a year later. In addition to a very good memory, goldfish also have good vision, being able to distinguish between shapes and colors. Sothe next time someone ignorantly compares your memory to that of a goldfish,don’t forget to thank them! （words:366）
【 Time5 】
7. Myth: Ostriches bury their heads in the sand when scared or threatened. Although this myth serves as the perfect metaphorfor someone who’s clearly in denial about something or other, the fact is thatit’s patently untrue. The truth is that ostriches, or any other bird or mammal,would not be able to breathe if its head were buried in the sand. The simple explanation for this myth is that ostriches bury their eggs in holes in the ground and often turn the eggs (with their beaks) and tend to the eggs several times a day. From a distance it often seems like the ostrich has its head buried in the sand.
6. Myth: Mother birds will reject their young once touched by humans. Birds have a very limited sense of smell, and the slight scent left by touching a baby bird will definitely not get detectedby its mother. In fact, birds are very devoted to their young and are unlikely to leave the nest because of an unknown scent – although they have been known to abandon their nests due to disturbance. Hardly ever will a bird abandon the nest with chicks, which is plainly against the nature of raising offspring.Returning a young bird to its nest can save the chick, and as long as there areno other major disturbances, it is highly unlikely that the mother will detect human contact.
5. Myth: Wild dolphins are friendly and will save humans in trouble. Dolphins don’t particularly care for humans;why would they? They are after all wild carnivores of the ocean. The myth that wild dolphins are friendly and will haste to your assistance when you’re introuble is a result of their curious nature which is often mistaken for caringor friendliness. For example, dolphins swimming next to boats are doing so in order to ride the boats wake, allowing them to use less energy to swim; not because of their love for all things human. In fact many people have been bitten or injured while attempting to swim with wild dolphins (we’re nottalking about the trained dolphins seen at marine parks). There is, however,one way in which dolphins are helping humans: recent research is helping scientists understand how dolphins survive shark attacks, and their tissue-regeneration and anti-bacterial properties are considered nothing short of a medical miracle. (words:399)
【 Time6 】
4. Myth: One human year is equivalent to sevendog years. Here’s something to think about: at a young age, a small dog is older than a large dog, but with age, the small dog becomes younger than the larger breed. How can this be? Turns out dog aging is quite complex, and the most important factor is that it’s related to the dogs physical size. Larger breeds age much faster than smaller breeds. It’s thoughtthat on average a two-year old dog compares to a teenager of 14 or 15 years ora young adult of 18 to 25 years, depending on the breed. Dog aging slows down after two years, debunking the seven to one ratio. The ratio between dog years and human years is therefore much more complex than seven to one, and there isno specific dog-to-human age ratio that is universally accepted.
3. Myth: A healthy dog’s nose is cold and wet. An old wives’ tale that has caused many apanic-stricken call to the vet. The temperature of your dogs nose typically fluctuates during the day, ranging from dry and hot (often when waking up inthe morning) to cold and wet later during the day. The moistness of your dog’snose is also no indicator of their health, as it could be moist due to a nasal cold, for example. As a dog owner, you can better understand your dog’s health by getting to know their typical behavior and noticing any changes from the norm. Are they not eating well lately, or sleeping restlessly? These behaviorswill give you a much better clue as to your dog’s well-being.
2. Myth: Dogs cannot see color, only black and white. Dogs can see color, but not as wide a spectrumas humans can. In addition to black, white and shades of grey they can also distinguish between blue-voilet and yellow-green colors. In would probably bemore correct to say that dogs are green-blind. Your pup may very well confusered, orange and green, as well as green-blue, gray, and shades of purple.Researchers have shown that a dog’s eye has both rods and cones, although theyonly have two cones whereas a human eye has three. Only if dogs had no cones atall would they have been restricted to seeing black and white.
1. Myth: Myth: Owls are the wisest among birds. Perhaps the earliest known link between owlsand wisdom is their association with Athena, as the Greek goddess of wisdom is often depicted holding an owl. With their overly large eyes and the constantserious, almost thoughtful look on their faces, owls give off the impression ofwisdom, of being a cut above the rest. From legends, folklore, children’s talesto Hollywood, owls have always been the night watchmen – sometimes sinister,always smart. Unfortunately owls are actually placed on the lower-end of intelligent birds, with the common crow considered the wisest among birds. (words:491) http://xue.youdao.com/biarticle.a?articleId=4158299928520254885&date=2013-08-19&position=read-history&channelType=public
How the Brain Remembers Pleasure:Implications for Addiction
【 Paraphrase7 】
Brain circuits have evolved to encourage behaviors proven to help our species survive by attaching pleasure to them. Eating rich food tastes good because it delivers energy and sex is desirable because it creates offspring. The same systems also connect in our mind's environmental cues with actual pleasures to form reward memories.
This study in rats supports the idea that the mammalian brain features several memory types, each using different circuits, with memories accessed and integrated as needed. Ancient memory types include those that remind us what to fear, what to seek out (reward), how to move (motor memory) and navigate (place memory). More recent developments enable us to remember the year Columbus sailed and our wedding day.
"We believe reward memory may serve as a good model for understanding the molecular mechanisms behind many types of learning and memory," said David Sweatt, Ph.D., chair of the UAB Department of Neurobiology, director of the Evelyn F. McKnight Brain Institute at UAB and corresponding author for the study. "Our results provide a leap in the field's understanding of reward-learning mechanisms and promise to guide future attempts to solve related problems such as addiction and criminal behavior."
The study is the first to illustrate that reward memories are created by chemical changes that influence known memory-related genes in nerve cells within a brain region called the ventral tegmental area, or VTA. Experiments that blocked those chemical changes -- a mix of DNA methylation and demethylation -- in the VTA prevented rats from forming new reward memories.
Methylation is the attachment of a methyl group (one carbon and three hydrogens) to a DNA chain at certain spots (cytosine bases). When methylation occurs near a gene or inside a gene sequence, it generally is thought to turn the gene off and its removal is thought to turn the gene on. This back-and-forth change affects gene expression without changing the code we inherit from our parents. Operating outside the genetic machinery proper, epigenetic changes enable each cell type to do its unique job and to react to its environment.
Furthermore, a stem cell in the womb that becomes bone or liver cells must "remember" its specialized nature and pass that identity to its descendants as they divide and multiply to form organs. This process requires genetic memory, which largely is driven by methylation. Note, most nerve cells do not divide and multiply as do other cells. They can't, according to one theory, because they put their epigenetic mechanisms to work making actual memories.
Natural pleasure versus addiction
The brain's pleasure center is known to proceed through nerve cells that signal using the neurochemical dopamine and generally is located in the VTA. Dopaminergic neurons exhibit a "remarkable capacity" to pass on pleasure signals. Unfortunately, the evolutionary processes that attached pleasure to advantageous behaviors also accidentally reinforced bad ones.
Addiction to all four major classes of abused drugs -- psychostimulants, opiates, ethanol and nicotine -- has been linked to increased dopamine transmission in the same parts of the brain associated with normal reward processing. Cues that predict both normal reward and effects of cocaine or alcohol also make dopamine nerve cells fire as do the experiences they recall. That had led to idea that drug addiction must take over normal reward-memory nerve pathways.
Along those lines, past research has argued that dopamine-producing neurons in the VTA -- and in a region that receives downstream dopamine signals from the VTA called the nucleus accumbens (NAC) -- both were involved in natural reward and drug-addiction-based memory formation. While that may true to some extent, this study revealed that blocking methylation in the VTA with a drug stopped the ability of rats to attach rewarding experiences to remembered cues but doing so in the NAC did not.
"We observed an important distinction, not in circuitry, but instead in the epigenetic regulation of that circuitry between natural reward responses and those that occur downstream with drugs of abuse or psychiatric illness," said Jeremy Day, Ph.D., a post-doctoral scholar in Sweatt's lab and first author for this study. "Although drug experiences may co-opt normal reward mechanisms to some extent, our results suggest they also may engage entirely separate epigenetic mechanisms that contribute only to addiction and that may explain its strength."
To investigate the molecular and epigenetic changes in the VTA, researchers took their cue from 19th century Russian physiologist Ivan Pavlov, who was the first to study the phenomenon of conditioning. By ringing a bell each day before giving his dogs food, Pavlov soon found that the dogs would salivate at the sound of the bell.
In this study, rats were trained to associate a sound tone with the availability of sugar pellets in their feed ports. This same animal model has been used to make most discoveries about how human dopamine neurons work since the 1990s, and most approved drugs that affect the dopamine system (e.g. L-Dopa for Parkinson's) were tested in it before being cleared for human trials.
To separate the effects of memory-related brain changes from those arising from the pleasure of the eating itself, the rats were separated into three groups. Rats in the "CS+" rats got sugar pellets each time they heard a sound cue. The "CS-" group heard the sound the same number of times and received as many sugar pellets -- but never together. A third tone-only group heard the sounds but never received sugar rewards.
Rats that always received sugar with the sound cue were found to poke their feed ports with their noses at least twice as often during this cue as control rats after three, 25-sound-cue sessions. Nose pokes are an established measure of the degree to which a rat has come to associate a cue with the memory of a tasty treat.
The team found that those CS+ rats (sugar paired with sound) that were better at forming reward memories had significantly higher expression of the genes Egr1 and Fos than control rats These genes are known to regulate memory in other brain regions by fine-tuning the signaling capacity of the connections between nerve cells. In a series of experiments, the team next revealed the methylation and demethylation pattern that drove the changes in gene expression seen as memories formed.
The study demonstrated that reward-related experiences caused both types of DNA methylation known to regulate gene expression.
One type involves attaching methyl groups to pieces of DNA called promoters, which reside immediately upstream of individual gene sequences (between genes), that tell the machinery that follows genetic instructions to "start reading here." The attachment of a methyl group to a promoter generally interferes with this and silences a nearby gene. However, ancient organisms such as plants and insects have less methylation between their genes, and more of it within the coding regions of the genes themselves (within gene bodies). Such gene-body methylation has been shown to encourage rather than silence gene expression.
Specifically, the team reported that two sites in the promoter for Egr1 gene were demethylated during reward experiences and, to a greater degree, in rats that associated the sugar with the sound cue. Conversely, spots within the gene body of both Egr1 and Fos underwent methylation as reward memories formed.
"When designing therapeutic treatments for psychiatric illness, addictions or memory disorders, you must profoundly understand the function of the biological systems you're working with," Day said. "Our field has learned from experience that attempts to treat addiction with something that globally impairs normal reward perception or reward memories do not succeed. Our study suggests the possibility that future treatments could dial down drug addiction or mental illness without affecting normal rewards."
(words:1272) http://www.sciencedaily.com/releases/2013/08/130825171530.htm
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发表于 2013-8-26 23:08:10
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very funny!
