short notes?

Supersonics:
                      Supersonic speed is a rate of travel of an object that exceeds the speed of sound (Mach 1). For objects traveling in dry air of a temperature of 20 °C (68 °F) at sea level, this speed is approximately 343 m/sMost modern fighter aircraft are supersonic, but there have been supersonic passenger aircraft, namely Concorde and the Tupolev Tu-144 whose flights were suspended in 2003. Both these passenger aircraft and some modern fighters are also capable of super cruise, a condition of sustained supersonic flight without the use of an afterburner. Due to its ability to super cruise for several hours and the relatively high frequency of flight over several decades. Some large bombers, such as the Tupolev Tu-160 and Rockwell/Boeing B-1B are also supersonic-capable.

 What is Pollen Allergy?
                                         Allergy to Polen is called Pollinosis. These pollens are usually from animophilous plants. Although their mission is to fertilize parts of other plants, many never reach their targets. Instead, they enter human noses and throats, triggering a type of seasonal allergic rhinitis called pollen allergy, which many people know as hay fever or rose fever (depending on the season in which the symptoms occur). Of all the things that can cause an allergy, pollen is one of the most widespread. Many of the foods, drugs, or animals that cause allergies can be avoided to a great extent; even insects and household dust are escapable. Short of staying indoors when the pollen count is high--and even that may not help--there is no easy way to evade windborne pollen. Antihistamines are seen to be effective against such allergies and can be used on physician’s prescription only.