Translation

Whenpeopleloselegs afteraccidents orillnesses, emergency care and artificial limbs often allow them to walk again. But newts in the same situation don't need doctors or artificial body parts. They can grow limbs back on their own.

A team of British scientists started their study with two simple observations: When you cut off a newt's leg at the ankle, only the foot grows back. If you cut off a leg at the base, the whole leg grows back. In both cases, the regrowth begins with stem cells.

But how do a newt's stem cells know when to regrow only a foot and when to regrow an entire leg? This question relates to another mystery: In newts, a severed leg will grow back only if the bundle of nerves in it also grows back. But if something prevents the nerve bundle from growing, the stem cells atthe siteof the wound won't multiply to produce a new leg.

In their study, the scientists zeroed in on a protein called nAG. When the team prevented nerves in a limb from growing, but added the nAG protein to stem cells in the limb, the limb still regrew.

The scientists suspect that nerves in the stub of a limb signal the release of the nAG protein. That protein seems to guide limb regrowth.

Peopleandothermammalshaveproteinsthatare similar to nAG. Further research into these compounds may someday help human limbs and organs heal themselves.

蝾螈重新长肢

当人们由于事故或疾病失去腿时，急诊加假肢常常能使他们重新行走。但蝾螈在同样的情况下却不需要医生或是假肢，它们自己会重新长出肢体。

一组英国科学家是从两个简单的观察结果开始他们对这问题的研究的：你如果在踝关节处切断蝾螈的腿，重新长出来的只是脚；而如果你把蝾螈的腿从根部切断，就会长出一整条腿。在以上两种情况下，重新生长的过程都是从干细胞开始的。

但是蝾螈的干细胞怎么知道什么时候只要重新长一只脚，什么时候要重新长一整条腿呢？这个问题牵涉到另一个谜：在蝾螈身上，受到重伤的腿只有在腿里的神经束也在重新生长的情况下才会重新生长。但如果有什么东西阻碍神经束生长，伤口处的干细胞就不会繁殖，因而长不出新腿。

科学家们在研究时把他们的注意力集中在一种叫做nAG的蛋白质上。当他们设法阻止肢体里的神经生长，但同时又把nAG蛋白质加进肢体的干细胞中时，这个肢体仍然会重新长出来。

科学家们猜想，肢体残余部分里的神经发出释放nAG蛋白质的信号，看来正是释放出来的这种蛋白质导致了肢体的重新生长。

人类和其他哺乳动物也有类似于nAG的蛋白质。对这种化合物做进一步研究有可能有朝一日能帮助人类肢体和器官自我疗伤。

（注意斜体部分的译法）

ListeningDevice Provides LandslideEarlyWarning

A device that provides early warning of a landslide by monitoring vibrations in soil is being tested by UK researchers. The (A) d________could save thousands of lives each year by warning when an area should be evacuated. Such natural disasters are (1) c_________in countries that experience sudden, heavy rainfall, and can also be triggered by earthquakes and even water (2) e______.

The most common way to monitor a slope for signs of an imminent (B) l________is to watch for changes in its shape. Surveyors can do this by measuring a site directly, or sensors sunk into boreholes or fixed above ground can be used to (C) m________the shape of aslope. Slopescan, however, changeshape without triggering a landslide, so either method is prone to causing false alarms. Now scientists have developed a device that listens for the vibrations caused when particles begin(3) m_________within a slope.

The device takes the form of a steel pipe dropped into a borehole in a slope. The borehole is filled in with gravel around the pipe to help(4) t________high-frequency vibrations generated by particles within the slope. These vibrations pass up the tube and are picked up by a sensor on the surface. Software analyses the (5) v_________signal to determine whether a landslide may be imminent.

The device iscurrentlybeingtestedina6-metre-tallartificial clay embankment in Newcastle, UK. Once it has been carefully and thoroughly tested, the device could be used to create a complete early-warning (6) s________fordangerous slopes. Locationswith asignificant risk oflandslides could definitely (D) b________from a machine like this. (A,B,C,D FOR CROSS, 1,2,3,4,5,6 FOR DOWN. The first letters of the absents were given)

Lucas'Puzzle

Leaving now the questions of formal geometrical propositions, I proceed to enumerate a few games or puzzles which depend mainly on the relative position of things. Some writers regard draughts, solitaire, chess, and such like games as subjects for geometrical treatment in the same way as they treat dominoes, backgammon, and games with dice in connection with arithmetic: but these discussions require too many artificial assumptions to correspond with the games as actually played or to be interesting.

The amusements to which I refer are of a more trivial description, in some cases it is difficult to say whether they should be classified as mainly arithmetical or geometrical, but the point is of no importance.

A problem with pawns (this problem was invented by the famous French mathematician Lucas) : on a row of seven squares on a chess-board, 3 white pawns (or counters) are placed on the 3 squares at one end, and 3 black pawns (or counters) are placed on the 3 squares attheotherend - themiddlesquare being left vacant. Each piece can move only in one direction; the white pieces can move from left to right, and the black pieces from right to left. If the square next to a piece is unoccupied, it can move on to that; or if the square beyond that is occupied by a piece of the opposite colour and the square next to it is unoccupied, then it can leap over that piece on to the unoccupied square beyond it. The object is to get all the white pawns in the places occupied initially by the black pawns and vice versa.

上期Read&

Comprehension答案

1. A 2. C

3. C 4. B

上期Crossword答案

A. controlB. scientists

C. better D. cloud

E. severeF. century

1. level 2. worst

3. treatment 4. greenhouse