Towards an understanding of nucleon spin structure: from hard to soft scales

The workshop "The Helicity Structure of the Nucleon" (BNL June 5, 2006) was organized as part of the 2006 RHIC & AGS Users' Meeting to review the status of the spin problem and future directions. The presentations can be found at http://www.phenix.bnl.gov/WWW/publish/caidala/UsersHelicityWorkshop2006/ . Recent data suggests small polarized glue and strangeness in the proton. Here we present a personal summary of the main results and presentations. What is new and exciting in the data, and what might this tell us about the structure of the proton ?Comment: 20 pages, to appear in Int. J. Mod. Phys.

Peaks in the Hartle-Hawking Wave Function from Sums over Topologies

Recent developments in ``Einstein Dehn filling'' allow the construction of infinitely many Einstein manifolds that have different topologies but are geometrically close to each other. Using these results, we show that for many spatial topologies, the Hartle-Hawking wave function for a spacetime with a negative cosmological constant develops sharp peaks at certain calculable geometries. The peaks we find are all centered on spatial metrics of constant negative curvature, suggesting a new mechanism for obtaining local homogeneity in quantum cosmology.Comment: 16 pages,LaTeX, no figures; v2: some changes coming from revision of a math reference: wave function peaks sharp but not infinite; v3: added paragraph in intro on interpretation of wave functio

The double torus as a 2D cosmos: groups, geometry and closed geodesics

The double torus provides a relativistic model for a closed 2D cosmos with topology of genus 2 and constant negative curvature. Its unfolding into an octagon extends to an octagonal tessellation of its universal covering, the hyperbolic space H^2. The tessellation is analysed with tools from hyperbolic crystallography. Actions on H^2 of groups/subgroups are identified for SU(1, 1), for a hyperbolic Coxeter group acting also on SU(1, 1), and for the homotopy group \Phi_2 whose extension is normal in the Coxeter group. Closed geodesics arise from links on H^2 between octagon centres. The direction and length of the shortest closed geodesics is computed.Comment: Latex, 27 pages, 5 figures (late submission to arxiv.org

Mutation analysis of HIF prolyl hydroxylases (PHD/EGLN) in individuals with features of phaeochromocytoma and renal cell carcinoma susceptibility

Germline mutations in the von Hippel–Lindau disease (VHL) and succinate dehydrogenase subunit B (SDHB) genes can cause inherited phaeochromocytoma and/or renal cell carcinoma(RCC). Dysregulation of the hypoxia-inducible factor (HIF) transcription factors has been linked to VHL and SDHB-related RCC; both HIF dysregulation and disordered function of a prolyl hydroxylase domain isoform 3 (PHD3/EGLN3)-related pathway of neuronal apoptosis have been linked to the development of phaeochromocytoma. The 2-oxoglutarate-dependent prolyl hydroxylase enzymes PHD1 (EGLN2), PHD2 (EGLN1) and PHD3 (EGLN3) have a key role in regulating the stability of HIF-a subunits (and hence expression of the HIF-a transcription factors). A germline PHD2 mutation has been reported in association with congenital erythrocytosis and recurrent extra-adrenal phaeochromocytoma. We undertook mutation analysis of PHD1, PHD2 and PHD3 in two cohorts of patients with features of inherited phaeochromocytoma (nZ82) and inherited RCC (nZ64) and no evidence of germline mutations in known susceptibility genes. No confirmed pathogenic mutations were detected suggesting that mutations in these genes are not a frequent cause of inherited phaeochromocytoma or RCC

The hydrolysis of geminal ethers: A kinetic appraisal of orthoesters and ketals

© 2016 Repetto et al. A novel approach to protecting jet fuel against the effects of water contamination is predicated upon the coupling of the rapid hydrolysis reactions of lipophilic cyclic geminal ethers, with the concomitant production of a hydrophilic acyclic hydroxyester with de-icing properties (Fuel Dehydrating Icing Inhibitors - FDII). To this end, a kinetic appraisal of the hydrolysis reactions of representative geminal ethers was undertaken using a convenient surrogate for the fuel-water interface (D2 O/CD3 CN 1:4). We present here a library of acyclic and five/six-membered cyclic geminal ethers arranged according to their hydroxonium catalytic coefficients for hydrolysis, providing for the first time a framework for the development of FDII. A combination of 1H NMR, labelling and computational studies was used to assess the effects that may govern the observed relative rates of hydrolyses