Images Dated 6th March 2003

Childhood asthma

Childhood asthma. Artwork of a child's respiratory system showing the mucus (yellow) and narrowing of the airways (bronchioles) in paediatric asthma. The mucus is revealed inside the bronchioles by sectioning the right lung (lower centre). An inset (lower right) shows the severe restriction of the air supply that results. In asthma, a trigger such as an allergen causes bronchiole narrowing. It is this that causes the inflammation and production of mucus. This mucus production is also seen in bronchitis, where inflammation usually arises from infection. Treatment is with bronchodilator drugs. Asthma is a chronic disease that usually arises in childhood and improves as the patient matures

© JOHN BAVOSI/SCIENCE PHOTO LIBRARY

Intra-cloud lightning at night, over Phoenix, USA

Lightning. Night-time view of intra-cloud lightning. Lightning occurs when a large, electrical charge builds up in a cloud. This is probably due to the rapid movement of water droplets and ice particles within the cloud. Large thunderclouds generally have very turbulent interiors. The charge induces an opposite charge somewhere else within the cloud, and a few "leader electrons" travel to this area. When one makes contact, there is a huge backflow of energy up the path of the electron. This produces a bright flash of light and temperatures of up to 30, 000 degrees celsius. Photographed over Phoenix, Arizona, USA

© Keith Kent/Science Photo Library

Photograph by Cyril Herbert, showing a graphic high level view of railway tracks

Photograph by Cyril Herbert, showing a graphic high level view of railway tracks on the approach to King's Cross Station

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