New Problem Linked to "Jet Lag" etc.

Many processes in the body naturally turn on or off with a near-clocklike precision. Sleeping and changes in body temperature， mood and metabol-ism - the process of turning food into energy - all follow a cycle. The body clock can get out of whack when a person travels to a distant place in a different time zone or works the night shift. Such disruptions may cause extreme tiredness.

Cells of the immune system usually help fight off infections and toxic invaders， but if they get too many together at one time， they could get rowdy. They can cause problems. And that's the case with TH17 cells. These cells normally kill germs by causing inflammation. Its a common body response to injuries. But too much inflammation can backfire. It could even underlie a variety of diseases， including asthma， allergies.

A research team reset the body clocks of mice by six hours. They did this by changing when the animals woke up and were exposed to light. The experiment mimicked the jet lag travelers experience when they journey far enough that their waking and sleeping times no longer match what their body clock was used to. Changes occurred in the gut of mice experiencing lab version of jet lag. Lots of TH17 cells accumu-lated. The scientists didn't find a similar hoard of immune cells in the guts of mice whose body clocks continued to keep normal time.

The scientists also exposed mice to chemicals that can trigger immune problems. These chemicals were more likely to trigger inflammation in jet-lagged mice than in mice whose body clocks were operating normally. That suggests that resetting the internal clock may make an animal more likely to develop immune disorders.

人体内的许多生物过程都以近似时钟的精确度自然地打开或关闭。睡眠、体温变化、情绪以及将食物转变为能量的新陈代谢等，都是按照一定周期运行的。当人们进行长距离旅行，到达不同时区或者上晚班时，生物钟就可能被打乱，从而导致极度疲倦。

免疫细胞通常能帮助抵抗感染和有毒入侵者，但是如果它们过多地聚集在一起，就会变得杂乱无章、引起麻烦。TH17型细胞即如此。免疫细胞用激发炎症的方式来杀灭细菌，这是人体对伤害的正常反应。但是炎症过于严重会起反作用，甚至可能引起哮喘、过敏、心脏病等疾病。

研究团队通过改变苏醒时间以及与灯光接触时间，对老鼠的生物钟进行了时差6个小时的重置。该实验模仿了旅行者的飞行时差体验。实验室中的老鼠在体验了实验环境中的飞行时差后体内发生了改变，大量免疫细胞堆积，而生物钟没有被扰乱的老鼠体内却没有类似的免疫细胞聚集现象。

另外，科学家们还让老鼠接触了会引起免疫问题的化学物质，结果发现相对于生物钟正常运转的老鼠而言，这些化学物质在有时差反应的老鼠身上引起炎症的可能性更大，这表明：重置生物钟容易使动物患上免疫性疾病。

（注意斜体字的译法）

One warm summer day， I heard the familiar tune of an ice cream truck outside my window. That night as I was going to bed I heard it again， faintly in the distance. But why was an ice cream truck cruising the neighborhood so late， at nearly （1） m ？ It wasn't. Gradually I realized the tune was not coming from outside my window. It had been playing inside my head.

It's true that some types of hallucinations（幻觉）are associated with mental （A） i . But many healthy people also experience "phantom" （幽灵）senses. Some hear music that isn't there. Some see visions. Others live with imaginary smells filling up their noses.

Hallucination is a unique and special （B） c of consciousness and mental life. Though hallucinations are probably as old as the human brain， our understanding of them has greatly increased over the last few （C） d . That's happening because of new technology that lets experts peer inside the （2） b . There is still a lot to discover about these ghosts in our heads.

Sometimes people hear a （3） m . Is the melody that you hear real， or is it all in your head？ Some people have a hard time telling. In one case， a woman woke to the sound of loud music. She asked her apartment manager to tell her （D） n to turn down their radio. In fact， there had been no music. But the woman didn't believe it， so she called the police to make a complaint about the noise！

Some researchers have looked at the brains of people who hear phantom tunes. Tim Griffiths is a UK neurologist. He used a （E） t called PET（Positron Emission Tomography， 正电子成像术）to view the brains of six people. All had hearing loss and heard phantom music. The PET scans showed blood flow in the brain， revealing which brain （F） r were most active. When his patients "heard" phantom music， a network of brain regions became very active. This （4） a

was similar to what neurologists see in the brains of normal people listening to real music.

（A， B， C， D， E， F FOR CROSS， 1， 2， 3， 4 FOR DOWN. The first letters of the absents were given）

They call me a man， but I'll never have a wife.

I was given a body， but not given life.

They made me a mouth， but didn't give me breath.

Water gives me life and sun brings me death.

What am I？