Near Threshold Pion Production via 2-H(p,pi-0)3-He

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Photoinduced transient stark spectroscopy in organic semiconductors: a method for charge mobility determination in the picosecond regime.

Published versio

Pionium Production in the Cooler

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Possible Quantum Spin Liquid States on the Triangular and Kagome Lattices

The frustrated spin-one-half Heisenberg model on triangualr and Kagome Lattices is mapped onto a single specis of fermion carrying statistical flux. The corresponding Chern-Simons gauge theory is analyzed at the Gaussian level and found to be massive. This provides a new motivation for the spin-liquid Kalmeyer-Laughlin wave function. Good overlap of this wave function with the numerical ground state is found for small clusters.Comment: 13 pages, revtex. IUCM-920

Efficiency of Exciton and Charge Carrier Photogeneration in a Semiconducting Polymer

Euan Hendry, Juleon M. Schins, L. P. Candeias, L. D. A. Siebbeles, and Mischa Bonn, Physical Review Letters, Vol. 92, article 196601 (2004). "Copyright © 2004 by the American Physical Society."We determine the efficiencies for the formation of excitons and charge carriers following ultrafast photoexcitation of a semiconducting polymer (MEH-PPV). The simultaneous, quantitative determination of exciton and charge photoyields is achieved through subpicosecond studies of both the real and the imaginary components of the complex conductivity over a wide frequency range. Predominantly excitons, with near-unity quantum efficiency, are generated on excitation, while only a very small fraction (<10-2) of free charges are initially excited, consistent with rapid (∼100  fs) hot exciton dissociation. These initial charges are very short lived, decaying on subpicosecond time scales

Pionium Production in the Cooler

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

The glycerophosphocholine acyltransferase Gpc1 contributes to phosphatidylcholine biosynthesis, long-term viability, and embedded hyphal growth in Candida albicans.

This is the final version. Available from Elsevier via the DOI in this record. Data availability: Data available upon request to Jana Patton-Vogt ([email protected]).Candida albicans is a commensal fungus, opportunistic pathogen, and the most common cause of fungal infection in humans. The biosynthesis of phosphatidylcholine (PC), a major eukaryotic glycerophospholipid, occurs through two primary pathways. In Saccharomyces cerevisiae and some plants, a third PC synthesis pathway, the PC deacylation/reacylation pathway (PC-DRP), has been characterized. PC-DRP begins with the acylation of the lipid turnover product, glycerophosphocholine (GPC), by the GPC acyltransferase, Gpc1, to form Lyso-PC. Lyso-PC is then acylated by lysolipid acyltransferase, Lpt1, to produce PC. Importantly, GPC, the substrate for Gpc1, is a ubiquitous metabolite available within the host. GPC is imported by C. albicans, and deletion of the major GPC transporter, Git3, leads to decreased virulence in a murine model. Here we report that GPC can be directly acylated in C. albicans by the protein product of orf19.988, a homolog of ScGpc1. Through lipidomic studies, we show loss of Gpc1 leads to a decrease in PC levels. This decrease occurs in the absence of exogenous GPC, indicating that the impact on PC levels may be greater in the human host where GPC is available. A gpc1Δ/Δ strain exhibits several sensitivities to antifungals that target lipid metabolism. Furthermore, loss of Gpc1 results in both a hyphal growth defect in embedded conditions and a decrease in long-term cell viability. These results demonstrate for the first time the importance of Gpc1 and this alternative PC biosynthesis route (PC-DRP) to the physiology of a pathogenic fungus.National Institute of Healt