1 You have signs of infection, such as: 2  Increased pain, swelling, warmth, or redness around the bite. 3  Red streaks leading from the bite. 4  Pus draining from the bite.  A fever.
A negative index of refraction due to three-dimensional chirality is demonstrated for abilayered metamaterial based on pairs of mutually twisted planar metal patterns in parallel planes, which alsoshows negative electric and magnetic responses and exceptionally strong optical activity and circular dichro-ism.
Refractive Index Every medium through which waves can move has a refractive index that indicates how fast they will travel. In the case of light, this is found by dividing its speed in a vacuum by its speed in that particular medium. It is a ratio between the speeds of the mediums, so it is not measured in any unit. The refractive index generally increases with the density of the medium: it is one for a vacuum and is greater than one for all known natural materials. Air typically has a refractive index of about 1.00029, but this varies with temperature and pressure. For water, the value is about 1.33, and for glass, about 1.50 â 1.75, depending on the type. Diamond has a very high refractive index of 2.417, which produces the well-known sparkling effect. Everyday Examples. The most common example used when discussing refraction is a straw in water. When a straw is placed in a glass of water and viewed from the side, it appears to be broken or bent. This is due to the difference in the refractive indices of air and water.