Look into hunters' eyes

    Have you ever been face to face with a cat or a sheep? If you have,you probably noticed that cats narrow their eyes to vertical (垂直的) slits (狭缝),while sheep have horizontal pupils (瞳孔).

     Why is the difference?

    Scientists from the Universities of California Berkeley and Durham in Britain may have the answer. Their research, published recently in the journal Science Advances, suggested that pupils' shapes could tell whether an animal is a hunter or gets hunted.

    The researchers took a close look at the eyes of 214 land animals.The challenge was to see if they could find a relationship between an animal's role in the food chain and the pupils' shapes.

    They found a pattern. Species with pupils that are vertical slits are more likely to be small ambush predators (捕猎者) – creatures that lie in wait for their lunch.In contrast,those with horizontal pupils are more likely to be plant-eating prey (猎物) species.

    Evolution chose the arrangement for a good reason.For hunters such as household cats,it appears that vertical pupils not only improve their ability to keep track of moving objects like mice,but also maximize (使最大化) their ability to judge the distances of the animals they hunt.

    However, an interesting discovery from the study is that the slit pupils are mostly linked to hunters that are close to the ground. Therefore, bigger cats who actively hunt down their prey, like tigers and lions, don't have slit pupils.

    On the other hand, for plant-eating prey animals, horizontal pupils give them a wider field of vision.When stretched (伸展) horizontally,the pupils allow for more light to enter from the front, back, and sides. Meanwhile, they also limit the amount of light from the sun above so the animal can see the ground better.“ Once they do find a predator,they need to see where they are running,” said leading researcher Martin Banks,a UC Berkeley professor of optometry (视光学).“They have to see well enough out of the corner of their eye to run quickly and jump over things.”

    But what happens when they bend down to eat? Researchers checked this by watching prey animals in the Oakland Zoo in California, US. They believe that when goats lower their heads to eat,their eyes rotate (旋转) to keep their pupils horizontal.

    So it seems that the eyes are indeed the window to the soul!

    Reading can be a social activity. Think of the people who belong to book groups. They choose books to read and then meet to discuss them. Now the website BookCrossing.com turns the page on the traditional idea of a book group.

    Members go on the site and register the books they own and would like to share. BookCrossing provides an identification number to stick inside the book. Then the person leaves it in a public place, hoping that the book will have an adventure, traveling far and wide with each new reader who finds it.

    Bruce Pederson, the managing director of BookCrossing, says, “The two things that change your life are the people you meet and books you read. BookCrossing combines both.”

    Members leave books on park benches and buses, in train stations and coffee shops. Whoever finds their book will go to the site and record where they found it.

    People who find a book can also leave a journal entry describing what they thought of it. E-mails are then sent to the BookCrossers to keep them updated about where their books have been found. Bruce Peterson says the idea is for people not to be selfish by keeping a book to gather dust on a shelf at home.

BookCrossing is part of a trend among people who want to get back to the “real” and not the virtual(虚拟). The site now has more than one million members in more than one hundred thirty-five countries.

    You may have never heard of Lanthanum, Cerium or Neodymium, but these elements (元素) and others known as “rare earth” play a major role in modern technology. They can actually be found in many places on the earth, but not in quantities that can be mined. Only a few countries — China, America, India, Australia, Brazil and Malaysia have any that can be mined enough to be traded.

Even though some of these elements such as Cerium are as abundant as Copper, they are not found in concentrated amounts on the earth's surface. They are often mixed together with other metals, which makes extraction (提取) of these elements an expensive and an environmentally messy process. It was due to this reason that the term “rare earth” was invented.

    Rare earth metals are used widely in our life. Rechargeable car batteries, computers, iPhones, DVD players, computer monitors, televisions, lighting, lasers, glass polishing, and superconductors all use quantities of rare earth metals. Also, with the advancement in “green” technology like solar panels, these shiny materials are becoming more important than ever. An average electric car uses 10 pounds of Lanthanum for its rechargeable battery!

    America has large deposits (存储量) of rare earths and has one of the first mines. It was openedin Southern California in 1940. The element “Europium” was the first metal to be separated in quantity for use in color televisions. However, in the 1980's and 1990's, as China started producing these elements in Inner Mongolia, the mines in America and elsewhere could not keep pace. The mine in Mountain Pass, California also failed environmental regulations and shut down in 2002.

    Now, recognizing the importance of having more than one supplier of this important resource, other rare earth owning countries like India and Australia are either dusting off their rare earth mines or speeding up their production. It is believed that the debate over rare earths will become louder in the coming months and years.

    It may sound strange, but cutting down a real tree for Christmas is actually greener than going with the artificial kind, one scientist says.

    “It is a little confusing to people,” said Clint Springer, a biologist at Saint Joseph's University in Philadelphia. Because of concerns over deforestation（砍伐森林）around the world, many people naturally worry that buying a real tree might contribute to that problem. But most Christmas trees for sale these days are grown not in the forest but on tree farms for the purpose of being cut.

    Moreover, from the viewpoint of greenhouse gases, real trees are “the obvious choice”. Live trees actively release oxygen as they grow, and meanwhile remove carbon dioxide from the atmosphere. After they have been cut and Christmas is over, they're usually cut into smaller pieces for mulch（覆盖物）. As mulch, the bits of trees very slowly release carbon dioxide back into the atmosphere. So in the end, a real Christmas tree is carbon neutral, putting the same amount of carbon dioxide back into the air as it took out (although much more slowly).

    The tree farms that grow the trees also replant after the trees are cut.  Artificial trees, on the other hand, don't come out even in the carbon balance. Petroleum（石油）is used to make the plastics in artificial trees and lots of carbon dioxide-creating energy is required to make and transport them. Because these trees just end up in the places where waste is buried under the ground after use, “those greenhouse gases are lost forever,” Springer said.

    Festivals are a great way to experience a destination in a different way. This article will fuel your wanderlust（漫游癖）and guide you to the best festivals.

    St Patrick's Day

    Where: Dublin, Ireland & New York, USA

    When: 17 March

    St Patrick's Day has taken place in New York city on March 17th since 1762. On this day, the whole city turns green. Many Irish make traditional bread on this day. It is one of the most fun days the of the year in New York City every year, when the whole city turns into a big green party.

    SXSW

    Where: Austin, USA

    When: 10-19 March

    Like free things? Yeah me too! Free food, drink and music sound good? Welcome to Austin, Texas. SXSW is a festival for those who work in the music and film industries. There are "free" shows. You di have to pay but not by handing over cash; you have to give some time to queue but it is worth it to see some popular stars.

    King's Day

    Where: Amsterdam, Netherlands

    When: 27 April

    Every year on April 27 Amsterdam turns a very bright color of orange for King's Day, which is the birthday of King Willem-Alexander. It is a crazy fun celebration when the center of the city is car, bus, and bike-free. It is a market day, when anyone can sell pretty much anything. Tips: Take a jacket with you, wear orange, and bring cash.

    Just for Laughs

    Where: Montreal, Canada

    When: 14-30 July

    For comedy lovers there is no other festival in the world better than Montreal's Just for Laughs. The festival concentrates most of its shows in the Latin Quarter. During the day street performers delight the crowds and at night the city comes alive with comedy all over the city.

Learning New Vocabulary during Deep Sleep

    Sleeping time is sometimes considered unproductive time. This raises the question whether the time spent asleep could be used more productively, e.g. for learning a new language? Up-to-now sleep research focused on the stabilization and strengthening of memories that had been formed during wakefulness. However, learning during sleep has rarely been examined. There is enough evidence for wake-learned information undergoing a revision by replay in the sleeping brain. The replay during sleep strengthens the still weak memory and leaves the newly acquired information in the pre-existing store of knowledge.

    If re-play during sleep improves the storage of wake-learned information, then first-play, i.e. the initial processing of new information, should also be possible during sleep.

    The research group of Katharina Henke examined whether a sleeping person is able to form new semantic（语义的）associations between played foreign words and translation words during the brain cells' active states, the so-called "Up-states." It turned out to be that what they thought was reasonable. When we reach deep sleep stages, our brain cells progressively coordinate their activity. During deep sleep, the brain cells are commonly active for a brief period of time before they jointly enter into a state of brief inactivity. The active state is called "Up-state" and the inactive state "Down-state". The two states alternate（交替）about every half-second.

    New evidence for sleep-learning challenges current theories of sleep and theories of memory. The concept of sleep that we are separated from the physical environment is no longer reasonable. "It's false that complex learning be impossible during deep sleep," says Simon Ruch, co-first-author. "In how far and with what consequences deep sleep can be applied for the acquisition of new information will be a topic of research in upcoming years," says Katharina Henke.

    The research group of Katharina Henke is part of the Interfaculty Research Cooperation (IRC). Thirteen research groups in medicine, biology and psychology are part of the IRC. The aim of these research groups is to gain a better understanding of the mechanisms（原理）involved in sleep and consciousness.