Disgraced Korean Cloner Blew It: He Did Make History

A new report by a team of US researchers says the human embryonic stem cells generated in a now-discredited experiment in South Korea, actually were a first. When Woo Suk Hwang announced three years ago he had created the first human patient-specific ESC, he was hailed as a science hero.

He said he did it with a cloning technique called somatic cell nuclear transfer, a tricky process in which a nucleus is inserted into a cell. Last year he and other researchers were fired after it turned out they fabricated data. But now, Harvard scientists say analysis of Hwang’s embryos show they were in fact the first-ever human cells created by parthenogenesis, virgin birth. The multiplying cells were the result of an egg alone.

The kicker is the Korean team had apparently hit upon a technique that scientists say could have resulted in a major advance for stem cell research, and were years ahead of anyone else. Had they been truthful, Hwang and colleagues might still be heroes, and embryonic stem cell therapies would be that much closer to reality.

Source: http://www.esa.int/esaCP/SEM9A3XAIPE_index_0.html

Geometric Construction of Roots of Quadratic Equation

A quadratic equation

with the leading coefficient a ≠ 0, has two roots that may be real - equal or different - or complex. The roots can be found from the quadratic formula:

In addition to the four arithmetic operations, the formula includes a square root. This is exactly the kind of operations that produce constructible numbers from constructible numbers. (By being "constructible" we mean a length (of a straight line) segment that could be constructed by straightedge and compass, given a unit length.) In fact, Descartes used this example to introduce his ideas of analytic geometry.

I came across a a generalization of Descartes' construction in an old translation (1910) of the classic The Theory of Geometric Constructions by August Adler (1863-1923).

(Read more...)

Source: http://www.cut-the-knot.org/changes.shtml