The west must be ready to resort to a pre-emptive nuclear attack to try to halt the "imminent" spread of nuclear and other weapons of mass destruction, according to a radical manifesto for a new Nato by five of the west's most senior military officers and strategists.

Calling for root-and-branch reform of Nato and a new pact drawing the US, Nato and the European Union together in a "grand strategy" to tackle the challenges of an increasingly brutal world, the former armed forces chiefs from the US, Britain, Germany, France and the Netherlands insist that a "first strike" nuclear option remains an "indispensable instrument" since there is "simply no realistic prospect of a nuclear-free world".

The separation of individual blood components is done with a specialized centrifuge (see apheresis). The earliest manual forms of plateletpheresis are done by the separation of platelets from multiple bags of whole blood collected from donors or blood sellers. Since each blood bag (usually 250 ml or 500 ml) contains a relatively small number of platelets, it can take as many as a dozen blood bags (usually from 5 to 10 bags, depending on the size of the blood bags and each donor's platelet count) to accumulate a single unit of platelets (enough for one patient). This greatly increases the risks of the transfusion. Each unit of platelets separated from donated whole blood is called a "platelet concentrate".

Modern automatic plateletpheresis allows the blood donor to give a portion of his platelets, while keeping his or her red blood cells and at least a portion of blood plasma. Therefore, no more than three units of platelets are generally harvested in any one sitting from a donor. Most donors will donate a "single" or "double" unit, however the occurence of "triples" has been increasing as more suitable donors are recruited.

Because platelets have a life-span of just 5 days, more platelet donors are always needed. Some centers are experimenting with 7 day platelets, but this requires additional testing and the lack of any preservative solutions means that the product is far more effective when fresh.

Even though red blood cells can also be collected in the process, most blood donation organizations do not do so because it takes much longer for the human body to replenish their loss. If the donor donates both red blood cells and platelets, it takes months, rather than days or weeks, before they are allowed to donate again (the guidelines regarding blood donation intervals are country-specific).

In most cases, blood plasma is returned to the donor as well. However, in locations that have plasma processing facilities, a part of the donor's plasma can also be collected in a separate blood bag (see plasmapheresis).