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有关于刀的事实

(2010-06-07 08:10:25)
标签:

杂谈

分类: 英译汉

大多数的刀,使用起来都是安全的。

 

英国莱斯特大学的法医工程专家,萨拉海恩斯沃思,问过自己类似的问题。制作家庭用刀需要降低刀具的危险性,就不需要降低其实用性吗?在一些国家中,如英国,最新数据显示,30%的谋杀案件都与刀或其他利器有关,其中许多都是从厨房抽屉里取出的,这个问题于此密切相关。

 

她和英国的法医病理学组的同事们经过研究得出的结论是“是的”。使用猪的尸体,这在某些方面类与人类的相类似,海恩斯沃思博士和她的同事研究了,刀具从不同的高度落下,要产生同样的作用力,就需要调节刀的重量,来得到同样的伤口。这个研究小组对刀的四项属性进行研究,刀末端的半径,末端的形状,刀刃的厚度和边缘的锐利程度,以确定到底是哪一部分,才能对物体造成最大程度的伤害。

 

答案竟然是尖端的半径。原因是,皮肤具有弹性,并且与刀的接触面积仅为一条线,与刀接触时,会对刀的压力进行分散。在某种程度上,一旦压力达到了皮肤的临界水平,皮肤就会破裂,刀片便进入到肌肉组织里面。锋利的刀就会以最快的速度克服皮肤对刀的分散力。

 

刀切得更深时需要的力量要比刀插入的力量小得多。事实上,那些被定罪的杀手们,主要的“功劳”要归功于他们的刀。鉴于有许多重要器官于皮肤的表面有着密切的关系(取决于受力面积,每2厘米深的伤口,就有41%肺部被扎破的可能性,超过60%的可能性会伤害到肝脏或动脉和6%的可能性会导致心脏穿透)这就意味着每一个(通常无意)造成的伤口都是很容易致命的。这也解释了为什么末端的锋利程度要比刀刃锋利程度最终造成的损伤严重的得多原因。

 

这一切回想起来是如此的显而易见,但它却是至关重要的,因为大多数菜刀工作的部分是刀刃,而并非是刀的末端。这意味着,刀具有系统的重新设计的主要宗旨是让刀的破坏性更小,而并非是让刀具更加有效。显然会有例外,圆角刀,后来被证明是破坏性最强的刀,毫无疑问是它们的末端所起的作用。不过,海恩斯沃思博士对面包刀进行测试,与它们的“羊脚”般的末端,根本就不能对皮肤造成一丁点的伤害。对于其他类型的厨房用具来说,也许亦是如此吧?


           Safer knives:The blunt truth

Most knives could be much safer yet still do their job

 

COULD household knives be made less dangerous without being made less useful? In countries such as Britain, where the latest figures suggest that 30% of murders are committed with knives or other sharp instruments, many of which have come out of a kitchen drawer, that is a pertinent question. It is one that Sarah Farnsworth, a forensic-engineering specialist at the University of Leicester, asked herself.

 

The answer that she and her colleagues at Britain’s Forensic Pathology Unit have now come up with is “Yes”. Using a pig’s carcass, which is similar in some ways to a human’s, Dr Farnsworth and her team studied the wounds made by different blades falling from a height that was adjusted, depending on the weight of the knife, to result in the same force. The team looked at four of a knife’s properties—the radius of the tip, the shape of the tip, the thickness of the blade and the sharpness of the edge—in order to determine what was doing the most damage.

 

The answer turned out to be the radius of the tip. The reason is that skin is elastic and will at first stretch and deflects a knife. At some point, however, a critical level of stress is reached and the skin is ruptured, allowing the blade to enter the muscle beneath. A sharp-pointed knife overcomes the initial deflection faster.

 

The force needed to go deeper is much less than that required for the entry. In fact, some convicted killers have commented on how their knife seemed to “fall into” the body of their victim after breaching his skin. That, combined with the closeness of many vital organs to the surface (depending on the area, a wound a mere 2cm deep has a 41% chance of puncturing the lungs, more than a 60% chance of rupturing the liver or the femoral artery and even a 6% chance of penetrating the heart) means a lethal wound is easily (and often unintentionally) inflicted. It also explains why the sharpness of the knife’s edge is less relevant to the damage ultimately caused than is the sharpness of its tip.

 

All this may sound obvious in retrospect, but it is important because the working part of most kitchen knives is the edge of the blade, not the tip. That suggests a systematic redesign might make most such knives less lethal without making them less effective. Obviously there would be exceptions. Filleting knives, which turned out to be the most lethal of all, certainly need their tips. But the bread knives tested by Dr Farnsworth, with their “sheep’s foot” shaped tips often failed to pierce the skin at all. A model for other kitchen equipment, perhaps?

 

原文出处:http://www.economist.com/sciencetechnology/tm/displayStory.cfm?story_id=13135660


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