In vitro fertilisation

In vitro fertilization or fertilisation (IVF) is a process by which an egg is fertilised by sperm outside the body: in vitro ("in glass"). The process involves monitoring and stimulating a woman's ovulatory process, removing an ovum or ova (egg or eggs) from the woman's ovaries and letting sperm fertilise them in a liquid in a laboratory. The fertilised egg (zygote) is cultured for 2–6 days in a growth medium and is then implanted in the same or another woman's uterus, with the intention of establishing a successful pregnancy.

IVF techniques can be used in different types of situations. It is a technique of assisted reproductive technology for treatment of infertility. IVF techniques are also employed in gestational surrogacy, in which case the fertilised egg is implanted into a surrogate's uterus, and the resulting child is genetically unrelated to the surrogate. In some situations, donated eggs or sperms may be used. Some countries ban or otherwise regulate the availability of IVF treatment, giving rise to fertility tourism. Restrictions on availability of IVF include to single females, to lesbians and to surrogacy arrangements. Due to the costs of the procedure, IVF is mostly attempted only after less expensive options have failed.

Test tube baby (disambiguation)

Test tube baby may refer to:

Other uses include:

Chain gang

A chain gang is a group of prisoners chained together to perform menial or physically challenging work as a form of punishment. Such punishment might include repairing buildings, building roads, or clearing land. This system existed primarily in the southern parts of the United States, and by 1955 had been phased out nationwide, with Georgia the last state to abandon the practice. Chain gangs were reintroduced by a few states during the "get tough on crime" 1990s, with Alabama being the first state to revive them in 1995. The experiment ended after about one year in all states except Arizona, where in Maricopa County inmates can still volunteer for a chain gang to earn credit toward a high school diploma or avoid disciplinary lockdowns for rule infractions. The introduction of chain gangs into the United States began shortly after the Civil War. The southern states needed finances and public works to be performed. Prisoners were a free way for these works to be achieved.

Synonyms and disambiguation

Chain gang (disambiguation)

A chain gang is a system of labor (usually forced) that involves groups of prisoners, chained together, doing menial labor.

Chain gang may also refer to:

Chain gang (cycling)

In the sport of cycling, a chain gang is a group of cyclists in a close knit formation usually of two parallel lines.

The formation comes from the fact that it is harder to cycle at the front of a group than in the shelter of another rider. The rider behind enjoys the slipstream of the rider in front. If one rider were to stay at the front all the time, he would tire and the whole group would slow down. If the lead is rotated, the effort is distributed across the group and the speed can be higher or the individual effort less.

This effect is very significant - up to a 40% reduction in effort for the slip-streaming riders while the lead rider also benefits from reduced drag (somewhat under 10%) due to the air not closing up after him.

The name chain gang is an allusion to the formation that riders adopt. The rider in the front of the group will take their share of the lead, then swing to the side and let the rest of the line come through, led by a new leader. The first rider then eases up and drops in behind the last rider in the line, staying in their slipstream until once again their turn comes to ride at the front.