Uniform families of minimal rational curves on Fano manifolds

It is a well-known fact that families of minimal rational curves on rational homogeneous manifolds of Picard number one are uniform, in the sense that the tangent bundle to the manifold has the same splitting type on each curve of the family. In this note we prove that certain --stronger-- uniformity conditions on a family of minimal rational curves on a Fano manifold of Picard number one allow to prove that the manifold is homogeneous

Nestings of rational homogeneous varieties

In this paper we study the existence of sections of universal bundles on rational homogeneous varieties -- called nestings -- classifying them completely in the case in which the Lie algebra of the automorphism group of the variety is simple of classical type. In particular we show that, under this hypothesis, nestings do not exist unless there exists a proper algebraic subgroup of the automorphism group acting transitively on the base variety.Comment: Major revision of the exposition. To appear in Tranformation Group

Wear-resistant ball bearings for space applications

Ball bearings for hostile environments were developed. They consist of normal ball bearing steel parts of which the rings are coated with hard, wear-resistant, chemical vapor deposited (C.V.D) TiC. Experiments in ultrahigh vacuum, using cages of various materials with self-lubricating properties, have shown that such bearings are suitable for space applications

Embryo Donation: The Government Adopts a Cause

The disposition of cryopreserved supernumerary embryos has become a divisive issue that puts to test the tenets of the culture of life promoted by the Vatican and President George W. Bush. The Bush administration has spent millions of dollars to promote embryo adoptions while imposing restrictions on federal funding for embryonic stem cell research. On the other hand, contemporary Catholic moral theologians and philosophers disagree on the question of the morality of embryo rescue or adoption because the Church strongly opposes in vitro fertilization, the donation of gametes and embryo cryopreservation, as evidenced recently during the Italian fertility law referendum. President Bush has relied on ideologically charged culture of life rhetoric to promote embryo adoptions as the only alternative to dispose of cryopreserved ( frozen ) human embryos. In doing so, he has alienated an important segment of Christian pro-lifers who support embryonic stem cell research. From a Catholic perspective, the culture of life as conceived by Pope John Paul II vigorously opposes stem cell research, but embryo donation has not found its place within the Catholic culture of life, and substituting the word adoption for donation does not solve the perplexing dilemma

Embryo Donation: The Government Adopts a Cause

The disposition of cryopreserved supernumerary embryos has become a divisive issue that puts to test the tenets of the culture of life promoted by the Vatican and President George W. Bush. The Bush administration has spent millions of dollars to promote embryo adoptions while imposing restrictions on federal funding for embryonic stem cell research. On the other hand, contemporary Catholic moral theologians and philosophers disagree on the question of the morality of embryo rescue or adoption because the Church strongly opposes in vitro fertilization, the donation of gametes and embryo cryopreservation, as evidenced recently during the Italian fertility law referendum. President Bush has relied on ideologically charged culture of life rhetoric to promote embryo adoptions as the only alternative to dispose of cryopreserved ( frozen ) human embryos. In doing so, he has alienated an important segment of Christian pro-lifers who support embryonic stem cell research. From a Catholic perspective, the culture of life as conceived by Pope John Paul II vigorously opposes stem cell research, but embryo donation has not found its place within the Catholic culture of life, and substituting the word adoption for donation does not solve the perplexing dilemma