一本教会你“做对”题的6级阅读书 day6 passage2
  • 00:00/00:00
  • LRC文本加载中...

    提示:点击文章中的单词,就可以看到词义解释

    Passage 2 Medibots: The World’s Smallest Surgeons 105
    世界上最小的外科医生 《新科学家》


    [00:02]Medibots : The world's smallest surgeons
    [00:06]A man lies unconscious on an operating table.
    [00:10]The enormous spider that hangs above him
    [00:13]has plunged four apparatus into his belly. The spider, made of white steel,
    [00:20]probes around inside the man's abdomen then withdraws one of its arms.
    [00:25]Held in the machine's claw is a neatly sealed bag
    [00:29]containing a scrap of bloody tissue.
    [00:32]This is a da Vinci robot. It has allowed a surgeon,
    [00:37]sitting at a control desk, to remove the patient's gland in a manner
    [00:42]that has several advantages over conventional methods.
    [00:45]Yet the future of robotic surgery may lie not only
    [00:49]with these large beasts but also with devices at the other end of
    [00:54]the size spectrum. The surgeons of tomorrow will include tiny robots
    [01:00]that enter humans' bodies and do their work from the inside,
    [01:04]with no need to open patients up or knock them out.
    [01:09]While tiny robots that swim through the blood
    [01:12]are still in the realm of fantasy, several groups are developing devices
    [01:17]a few millimetres in size. The first generation of "mini-medibots"
    [01:23]may enter our bodies through our ears, eyes and lungs, to deliver drugs,
    [01:28]take tissue samples or install medical devices.
    [01:33]The engineering challenges are great,
    [01:35]including developing new methods of driving force and power supply.
    [01:40]Nevertheless, the first prototypes are already being tested in animals
    [01:46]and could move into tests on people in the not-too-distant future.
    [01:51]"It's not impossible to think of this happening in five years," says Brad Nelson,
    [01:57]a roboticist at the Swiss Federal Institute of Technology in Zurich.
    [02:03]"I'm convinced it's going to get there."
    [02:06]It was the 1970s that saw the arrival of minimally invasive surgery
    [02:12]or keyhole surgery as it is also known. Instead of cutting open the body
    [02:17]with large cuts, surgical tools are inserted through holes as small as
    [02:23]1 centimetre in diameter and controlled with external handles.
    [02:28]Some operations are now done this way, reducing blood loss,
    [02:32]pain and recovery time.
    [02:36]Combining keyhole surgery with the da Vinci system
    [02:40]means the surgeon no longer handles the instruments directly,
    [02:44]but via a computer control panel. This allows greater precision,
    [02:49]as large hand gestures can be scaled down to small instrument movements,
    [02:55]and any hand tremor is eliminated.
    [02:57]There are over 1000 da Vincis being used in clinics around the world.
    [03:04]Heart crawler
    [03:06]There are several ways that such robotic surgery may be further enhanced.
    [03:12]Various jointed, snake-like tools
    [03:15]are being developed to access hard-to-reach areas. One such device,
    [03:21]the "i-Snake", is controlled by a vision-tracking device
    [03:25]worn over the surgeon's eyes.
    [03:28]It should be ready for testing on patients within four years,
    [03:32]says developer Guang-Zhong Yang, a roboticist at Imperial College London.
    [03:38]With further advances in miniaturisation,
    [03:41]the opportunities grow for getting medical devices
    [03:45]inside the body in novel ways. One miniature device
    [03:49]that is already tried and tested is a camera in a capsule
    [03:54]small enough to be swallowed.
    [03:58]In conventional test, a camera on the end of a flexible tube
    [04:02]is inserted through the mouth,
    [04:04]but this does not allow it to reach the middle part of the gut.
    [04:09]The 25-millimetre-long capsule camera, on the other hand,
    [04:13]can observe the entire gut on its journey.
    [04:17]More sophisticated versions are being developed
    [04:20]that can also release drugs and take samples.
    [04:25]The capsule camera has no need to propel itself
    [04:28]because it is pushed along by the normal muscle contractions of the gut.
    [04:34]For devices used elsewhere in the body,
    [04:37]some scientists are developing new mechanisms for driving force
    [04:42]and power supply on a miniature scale.
    [04:46]One solution is to have wires connecting the robot to a control unit
    [04:51]that remains on the outside of the body.
    [04:54]This is the case for a robot being developed for heart surgery,
    [04:58]called HeartLander.
    [05:01]Operating on the heart has always presented enormous challenges,
    [05:05]says Marco Zenati, a heart surgeon at the University of Pittsburgh,
    [05:10]Pennsylvania, who is one of the device's inventors.
    [05:14]Conventionally the heart is stopped
    [05:16]and the patient hooked up to a heart-lung machine.
    [05:20]A more recent approach is to perform keyhole surgery on the beating heart,
    [05:26]but even so several cuts must be made,
    [05:29]and the left lung must be partly deflated to allow access.
    [05:34]The HeartLander robot is designed to be delivered to the heart
    [05:38]through a single keyhole cut, from where it can crawl to the right.
    [05:43]The 20-millimetre-long HeartLander has front and rear foot-pads
    [05:48]with suckers on the bottom, which allow it to move along like a worm.
    [05:53]The surgeon watches the device with X-ray video or a magnetic tracker
    [05:58]and controls it with a control stick. Alternatively,
    [06:03]the device can navigate its own path to a spot chosen by the surgeon.
    [06:08]The HeartLander has several possible uses.
    [06:11]It can be fitted with a needle attachment to take tissue samples,
    [06:16]for example, or used to inject stem cells
    [06:20]or gene therapies directly into heart muscle.
    [06:24]There are several such agents in development,
    [06:27]designed to promote the regrowth of muscle or blood vessels
    [06:31]after a heart attack. The team is testing the device on pigs
    [06:36]and has so far shown
    [06:38]that it can crawl over a beating heart to inject a marker dye at a target site.
    [06:46]Another use would be to deliver pacemaker electrodes for a procedure,
    [06:51]when the heart needs help in coordinating its rhythm.
    [06:56]At the moment, the electrodes are delivered to the heart
    [06:59]by pushing them in through a vein. Riviere's group
    [07:03]is devising electrodes that the HeartLander
    [07:06]could attach to the outer surface of the heart.
    [07:10]They have tested this approach successfully on one live pig,
    [07:15]and expect to start trials in people in about four years.
    [07:19]Riviere says there is growing evidence to show that the technique works best
    [07:25]when the electrodes are sited in certain areas
    [07:28]that are hard to access from inside the veins.
    [07:32]"The HeartLander can crawl around to the best position," he notes.
    [07:38]While the robot could in theory be used in other parts of the body,
    [07:43]in its current incarnation it has to be introduced
    [07:46]through a keyhole incision thanks to its size and
    [07:50]because it trails wires to the external control box.
    [07:54]Not so for smaller robots under wireless control.
    [07:59]One such device in development is 5 millimetres long
    [08:04]and just 1 millimetre in diameter, with 16 vibrating legs.
    [08:10]Early versions of the "ViRob" had on-board power,
    [08:15]but the developers decided that made it too bulky.
    [08:19]Now it is powered externally, by a nearby electromagnet
    [08:23]whose field fluctuates about 100 times a second,
    [08:28]causing the legs to flick back and forth.
    [08:32]The legs on the left and right sides respond best to different frequencies,
    [08:37]so the robot can be steered by adjusting the frequency.
    [08:41]ViRob's developers at the Technion-Israel Institute of Technology in Haifa,
    [08:47]are investigating several applications including taking tissue samples,
    [08:51]delivering cancer drugs and getting a camera to hard-to-reach areas,
    [08:57]such as deep within the lungs. The size of the camera is a limiting factor
    [09:02]the smallest models in development are 1.5 millimetres in diameter
    [09:07]but cameras get smaller every year, notes engineer Moshe Shoham.
    [09:13]The team would like their device to operate inside large blood vessels,
    [09:19]but it is not yet powerful enough to withstand blood flow.
    [09:23]"We don't want it swept away," says Shoham.
    [09:27]One application for ViRob may benefit people born with fluid on the brain
    [09:33]as it may be able to extend the life of the shunts placed
    [09:37]in the brain to drain the excess fluid.
    [09:40]Over time such shunts tend to get blocked,
    [09:44]and so need replacing every five to 10 years,
    [09:48]entailing major brain surgery. Shoham says a self-cleaning shunt
    [09:53]could be made by installing a ViRob permanently inside.
    [09:58]In fact, if millimetre-sized devices prove their worth,
    [10:03]they will attract more funding to kick-start the research.
    [10:07]Small devices that do something useful will convince people
    [10:11]that it's not just science fiction.
     

    0/0
      上一篇:一本教会你“做对”题的6级阅读书 day6 passage1 下一篇:一本教会你“做对”题的6级阅读书 day6 passage3

      本周热门

      受欢迎的教程

      下载听力课堂手机客户端
      随时随地练听力!(可离线学英语)