Legionnaire's disease

Legionnaire's Disease is a bacterial infection that causes pneumonia. Symptoms range from mild to very severe and include fatigue, fever and a dry cough. In serious cases, patients develop difficulty in breathing and diarrhoea. About 20% of people who contract the disease die. However, antibiotics are generally an effective treatment.

The bacteria that cause the disease live in water and under favourable conditions they can multiply to high levels. Warm stagnant water, found in hot water tanks or large air conditioning systems, is a favourite breeding ground. People can be infected if they inhale airborne water droplets that contain the bacteria.



Lyme disease

Lyme disease is caused by the bacterium Borrelia burgdorferi and is spread by deer ticks. The bacteria enter the skin when the ticks bite and, up to a month after the bite, spread to other organs through the blood stream or the lymph system.

The main symptoms of Lyme disease are a large red spot where the bite occurred, fatigue, chills, fever, headache and muscle and joint aches. Some people also suffer from vomiting, sore throat and enlarged lymph glands whilst a few people go on to develop arthritis or problems with nerve function.

Lyme disease can be treated with antibiotics but prevention by covering up skin when walking through areas where there are deer is best.

M



magnetism

Magnetism is the property that certain substances display of attracting or repelling each other. Only some materials, such as iron or nickel, can freely align their internal structure to produce this effect.

The Earth possesses its own magnetic field, which is generated by dynamic motions in its molten iron core. Magnetic materials can align themselves with this field. Magnetite (a form of iron oxide) was known to the ancient Chinese, who are thought to have used its magnetic properties in making compasses as far back as 2,500 BC.



mass (ie atomic mass)

Different types of atoms [see atoms] contain different numbers of protons, neutrons and electrons. The total mass of an atom, called its atomic mass, is made up of all the particles it contains. Protons and neutrons have nearly the same mass as each other, but electrons have far less. Therefore the atomic mass of an atom is normally taken to be the sum of its protons and neutrons.

This atomic mass can be written before the symbol for the element. For example, normal carbon contains six protons and six neutrons, and can be written 12C.



menopausal

Menopausal is a term used to describe women who are going through or have gone through the menopause. During the menopause, menstruation (periods) tends to become erratic and eventually stops altogether. The menopause is not fully understood but it is thought that as women age, their ovaries gradually stop responding to the hormones that stimulate ovulation. The ovaries also produce less of the hormone oestrogen and it is thought that this might be the cause of some of the physical and emotional changes experienced by women during the menopause.



meteorological

Meteorological is an adjective used to describe topics that fall into the science of meteorology. Meteorology deals with atmosphere, the processes within it and how it interacts with the surface of the Earth. The state of the atmosphere at a specific place and time is known as the weather.



microbes

Microbe is a term for any organism that is too small to be seen with the naked eye. They are also called micro-organisms. Some common microbes are viruses, bacteria, yeasts and moulds.



microbiologists

Microbiologists study organisms such as viruses, bacteria, yeasts and moulds that are too small to see with the naked eye. These tiny organisms are called micro-organisms or sometimes microbes.

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Nasa

Nasa is an abbreviation of National Aeronautics and Space Administration. Nasa is responsible for all civil space activities, including research and development, in the US. The European equivalent is called, unsurprisingly, Esa.

The Nasa website is at www.Nasa.gov and has huge amounts of information on all aspects of Nasa's work.



nature/nurture debate

Are we the product of our genes alone or are we dependent on the environment in which we grow up? This is the basis of the nature/nurture debate but few, if any, people now hold such polarised views. Most now believe that our individual characteristics are the result of an interaction between our genes and our environment. However, there is still much debate about this interaction and how it might work.

The debate also raises ethical issues – if a person is found to possess a gene that has been linked with crime, does this mean that nothing can be done to prevent this person committing crime? Should they be locked away for the good of society even if they have not yet committed a crime?



neurotransmitter

A neurotransmitter is a chemical that transmits a signal between nerve cells. An electrical impulse along a nerve activates the release of a neurotransmitter chemical at the nerve ending.

The chemical is then released across the gap between two nerves and creates an electrical impulse in the next cell. In this way a signal is relayed from nerve cell to nerve cell.



nitric acid

Nitric acid, known to alchemists as aqua fortis (strong water), was one of the first strong mineral acids to be discovered. It was obtained by distilling together saltpetre (potassium nitrate) and green vitriol (iron sulphate) or alum (potassium aluminium sulphate). Nitric acid could be used to separate silver from gold, as silver dissolves in the acid while gold does not.

Today it is used in many chemical processes, particularly in the making of nitrate-based fertilisers.

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obstetrics

This is the branch of medicine concerned with pregnancy and birth. Specialists are known as obstetricians.

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pagan

Before Christianity spread throughout Europe, people followed many different religions. As most tribes had a common Indo-European ancestor, common gods and themes can be traced between them.

The pagan religions were polytheistic, worshipping more than one god. The oldest ones had a mother-goddess as the central figure, but by pre-Christian times whole pantheons of gods and goddesses were worshipped, each with their own attributes. Nature was seen as a powerful force in peoples' lives, and was treated with a reverence and importance not seen in Christianity.



pathogen

A pathogen is any micro-organism that is capable of causing disease. A pathogen will only infect a certain species; human pathogens will only infect us.



plague

There are two main kinds of plague: bubonic and pneumonic. Both are caused by the bacterium Yersinia pestis, which is spread by flea bites or caught through inhaling infected droplets from coughs and sneezes.

Bubonic plague develops when the bacteria infect the lymph nodes which then swell and are called buboes.

Pneumonic plague develops when the bacteria infect the lungs which then quickly fill with a frothy bloody liquid.

Early treatment with antibiotics is often very effective and vaccines are available for those most at risk.



proteins

Proteins are the body's building blocks and humans have over 10,000 different types. Proteins are incredibly complex molecules made up of one or more sequences of amino acids. The order of the amino acids in a protein is genetically determined – genes are the recipes for making proteins.



protein crystals (also see crystal growth)

Proteins are the body's building blocks and humans have over 10,000 different types. Scientists want to find out how proteins work so that they can understand the body's chemistry and hopefully develop new pharmaceuticals.

Proteins are incredibly complex molecules made up of one or more sequences of amino acids and how they work is directly related to their shape. Their shape and structure can be studied by shining X-rays through protein crystals – but to do this accurately very pure crystals are needed. The weightless conditions of the ISS mean that the solutions from which the protein crystals are grown are not subject to the same convection currents as on Earth. This allows larger, purer crystals to be produced.



pneumonic plague – see plague