Cardiac arrest happens when the heart suddenly stops beating. This can be caused by a heart attack in which the heart's demand for oxygen is not met and the heart muscle begins to die. With cardiac arrest, normal circulation of blood stops, because of a failure of the heart to contract. This results in the body not getting enough oxygenated blood, which causes cells to start to die from oxygen starvation. Cerebral hypoxia (lack of oxygen to the brain) makes a person lose consciousness and stop breathing, and this makes the heart stop completely. Unless the person is in hypothermia, brain damage usually occurs after three to five minutes. (In some cases, the person is put into hypothermia on purpose, to help the person recover better with less damage.)
Cardiac arrest is a medical emergency. If it is treated early enough, some of the damage done can be reversed in certain groups of patients. When cardiac arrest leads to a person's death, this is called sudden cardiac death (SCD). First aid treatment for cardiac arrest usually begins with cardiopulmonary resuscitation (CPR) to keep oxygenated blood flowing until medical treatment is available.
Huguenots
From the 16th to the 18th century the name Huguenot was describing a member of the Protestant Reformed Church of France. They are sometimes known as the French Calvinists.
After the Saint Bartholomew's Day Massacre in 1572 and the French Wars of Religion hundreds of thousands of French Protestants fled France, some to the East End of London, specifically Soho and Spitalfields. The Treaty of Nantes allowed them to stay in France without being massacred
La Rochelle
La Rochelle is a city in the Charente-Maritime department and a seaport in western France near the Bay of Biscay. The Huguenots there rebelled in 1627 and 1628.
La Rochelle Business School is in the city.
La Rochelle is twinned with:
Combustion
Combustion is a reaction of a fuel with an oxidant to give out heat. The release of heat can produce light in the form of a flame.
Car engines and rocket engines both work by combustion. Combustion in a Ferrari car motor is different from combustion in a rocket engine. Car combustion is gas burning and exploding in cylinders called pistons again and again to push them up and down, making the car move. Rocket combustion is made by rocket fuel exploding out of the back of the rocket moving it up. The burning of most substances is bad for the environment and the ozone layer because it can let off greenhouse gases such as carbon dioxide. Hydrogen burns cleanly and gives off a lot of heat, but it does not produce much power, and is highly explosive.
During combustion, fuel reacts with oxygen and heat, then releases energy. Complete combustion happens in a plentiful supply of oxygen. Complete combustion releases more energy than incomplete combustion. Incomplete combustion occurs when the supply of air is limited, or poor. Incomplete combustion also creates carbon monoxide, and more soot. Several factors must be considered when choosing the best fuel for a particular purpose. Fuels are substances that react with oxygen to release useful energy. Most of the energy is released as heat, but light energy is also released. About 21 per cent of the air is oxygen. When a fuel burns in plenty of air, it receives enough oxygen for complete combustion. Complete combustion needs a plentiful supply of air so that the elements in the fuel react fully with oxygen. Fuels such as natural gas and petrol contain hydrocarbons. These are compounds of hydrogen and carbon only. Combustion is a high-temperature oxidation reaction.
Nanometre
The nanometre (symbol: nm) is a unit used to measure length in the metric system. It is equal to one billionth of a metre (). The name combines the SI prefix "nano-" (from the Ancient Greek , ', "dwarf") with the parent unit name "metre" (from Greek , ', "unit of measurement"). It can be written in scientific notation as 1×10 m.
The nanometre is often used to express very tiny dimensions, such as measuring atoms. The nanometre is also commonly used to measure the wavelength of electromagnetic radiation near the part of the spectrum that can be seen by humans. Visible light ranges from around 400 to 800 nm.
The nanometre was formerly called the millimicrometre (or the millimicron). This is because it is 1/1000 of a micrometre, and was written with the symbol mµ (or sometimes µµ).
Caterpillar
A caterpillar is a young butterfly or moth that has just hatched out of its egg. A caterpillar is a kind of larva. When it is older, the caterpillar will turn into a pupa (also known as a chrysalis), and then later the pupa will turn into a butterfly.
Caterpillars usually have three pairs of small, but noticeable, true legs at the front and up to 5 pairs of fleshy false legs at the back.
Caterpillars are commonly found feeding on leaves, but they are also found inside living stems and branches or on the roots of plants and dead wood.
Most caterpillars are shades of green or brown and are relatively hairless, although in many families caterpillars are very hairy and often brightly coloured. Some species are pests of growing plants, carpets, woollens, organic fabrics and stored food products.
Caterpillars are an important source of food for birds and other invertebrates and many species help dead animals and plants decompose.
Examples of different kinds of caterpillars.
Hummingbird
Hummingbirds are small birds of the family Trochilidae.
They are among the smallest of birds: most species measure 7.5–13 cm (3–5 in). The smallest living bird species is the 2–5 cm Bee Hummingbird. They can hover in mid-air by rapidly flapping their wings 12–80 times per second (depending on the species). They are also the only group of birds able to fly backwards. Their rapid wing beats do actually hum. They can fly at speeds over 15 m/s (54 km/h, 34 mi/h).
Hummingbirds help flowers to pollinate, though most insects are best known for doing so. The hummingbird enjoys nectar, like the butterfly and other flower-loving insects, such as bees.
Hummingbirds do not have a good sense of smell; instead, they are attracted to color, especially the color red. Unlike the butterfly, the hummingbird hovers over the flower as it drinks nectar from it, like a moth. When it does so, it flaps its wings very quickly to stay in one place, which makes it look like a blur and also beats so fast it makes a humming sound. A hummingbird sometimes puts its whole head into the flower to drink the nectar properly. When it takes its head back out, its head is covered with yellow pollen, so that when it moves to another flower, it can pollinate. Or sometimes it may pollinate with its beak.
Like bees, hummingbirds can assess the amount of sugar in the nectar they eat. They reject flowers whose nectar has less than 10% sugar. Nectar is a poor source of nutrients, so hummingbirds meet their needs for protein, amino acids, vitamins, minerals, etc. by preying on insects and spiders.
Most hummingbirds have bills that are long and straight or nearly so, but in some species the bill shape is adapted for specialized feeding. Thornbills have short, sharp bills adapted for feeding from flowers with short corollas and piercing the bases of longer ones. The Sicklebills' extremely decurved bills are adapted to extracting nectar from the curved corollas of flowers in the family Gesneriaceae. The bill of the Fiery-tailed Awlbill has an upturned tip, as in the Avocets. The male Tooth-billed Hummingbird has barracuda-like spikes at the tip of its long, straight bill.
The two halves of a hummingbird's bill have a pronounced overlap, with the lower half (mandible) fitting tightly inside the upper half (maxilla). When hummingbirds feed on nectar, the bill is usually only opened slightly, allowing the tongue to dart out into the nectar.