Explicit Construction of Yang-Mills Instantons on ALE Spaces

We describe the explicit construction of Yang-Mills instantons on ALE spaces, following the work of Kronheimer and Nakajima. For multicenter ALE metrics, we determine the abelian instanton connections which are needed for the construction in the non-abelian case. We compute the partition function of Maxwell theories on ALE manifolds and comment on the issue of electromagnetic duality. We discuss the topological characterization of the instanton bundles as well as the identification of their moduli spaces. We generalize the 't Hooft ansatz to SU(2) instantons on ALE spaces and on other hyper-Kahler manifolds. Specializing to the Eguchi-Hanson gravitational background, we explicitly solve the ADHM equations for SU(2) gauge bundles with second Chern class 1/2, 1 and 3/2.Comment: 59 pages, epsf.tex, 2 figures included, uuencoded fil

The Law of Hammurabi and Its Audience

Since its discovery and decipherment at the turn of the twentieth century, the inscription of the Law Stele of Hammurabi, popularly known as the Code of Hammurabi, has been one of the most important sources for study of ancient Near Eastern law. But the Stele is more than just the vehicle for its inscription: its text and imagery were designed, quite deliberately, to incorporate elements of performativity and memorialization that would have resonated in its Mesopotamian cultural setting. Through a never-ending cycle of performance and reception, the Stele publicized to its audience standards for justice while simultaneously preserving an enduring record of Hammurabi\u27s commitment to just ways for the land

Phosphate-solubilizing potential of the nematophagous fungus Arthrobotrys oligospora

International audienceThe nematophagous fungus Arthrobotrys oligospora was tested in vitro and in vivo for its ability to solubilize rock phosphate. Three types of rock phosphate (RP) from Burkina Faso (KRP), Senegal (TRP), and Mali (TIRP) were used at four concentrations for the in-vitro experiment. All three types of RP were solubilized by the fungus. The maximum quantity of P recovered in solution was obtained with TRP, 12.5% for an application of 1 g L-1. The effect of TRP and A. oligospora applied separately or in combination was tested in vivo on the growth of A. holosericea. In a P-deficient soil without addition of RP, P solubilization was increased by addition of A. oligospora. The P uptake by plants growing in soil amended with TRP and inoculated with A. oligospora was significantly higher compared to noninoculated controls, thus demonstrating the ability of the fungus to solubilize additional phosphate from RP in vivo

Electroweak symmetry breaking and fermion masses from extra dimensions

We study higher-dimensional non-supersymmetric orbifold models where the Higgs field is identified with some internal component of a gauge field. We address two important and related issues that constitute severe obstacles towards model building within this type of constructions: the possibilities of achieving satisfactory Yukawa couplings and Higgs potentials. We consider models where matter fermions are localized at the orbifold fixed-points and couple to additional heavy fermions in the bulk. When integrated out, the latter induce tree-level non-local Yukawa interactions and a quantum contribution to the Higgs potential that we explicitly evaluate and analyse. The general features of these highly constrained models are illustrated through a minimal but potentially realistic five-dimensional example. Finally, we discuss possible cures for the persisting difficulties in achieving acceptable top and Higgs masses. In particular, we consider in some detail the effects induced in these models by adding localized kinetic terms for gauge fields