On the 1/Q correction to the C-parameter at two loops

We provide an analytical calculation at the two loop level of the real non-abelian contribution to the leading (1/Q) correction to the mean value of the C parameter in e+e- annihilation, to complement the existing calculation of the abelian contribution; and we compare the result with the numerical `Milan factor' obtained using the soft approximation. We find agreement with the previous results. The use of the pinch technique to separate the various contributions yields insights into the structure of renormalon-type diagrams in a non-abelian theory.Comment: 17 pages, 2 figure

Power Corrections to Fragmentation Functions in Non-Singlet Deep Inelastic Scattering

We investigate the power-suppressed corrections to the fragmentation functions of the current jet in non-singlet deep inelastic lepton-hadron scattering. The current jet is defined by selecting final-state particles in the current hemisphere in the Breit frame of reference. Our method is based on an analysis of one-loop Feynman graphs containing a massive gluon, which is equivalent to the evaluation of leading infrared renormalon contributions. We find that the leading corrections are proportional to $1/Q^2$, as in $e^+e^-$ annihilation, but their functional forms are different. We give quantitative estimates based on the hypothesis of universal low-energy behaviour of the strong coupling.Comment: 14 pages, 4 figures, LaTeX2e, uses JHEP.cls (included) and epsfi

Aboriginal Mental Health - What Works Best

In July 1999, the first meeting of the Aboriginal Mental Health Committee was held at the Longhouse, UBC . This discussion paper represents the discussions of the Committee\u27s working group based on their viewpoints and the literature available in the area of Aboriginal Mental Heath, including information from the Assembly of First Nations (AFN) and Inuit Tapirisat of Canada (ITC) Environmental Scan (Federal) and the Royal Commission Reports on Aboriginal Peoples. The paper is intended for distribution across the province for input in focus group format

Imaging of nuclear magnetic resonance spin–lattice relaxation activation energy in cartilage

Samples of human and bovine cartilage have been examined using magnetic resonance imaging to determine the proton nuclear magnetic resonance spin–lattice relaxation time, T1, as a function of depth within through the cartilage tissue. T1 was measured at five to seven temperatures between 8 and 38°C. From this, it is shown that the T1 relaxation time is well described by Arrhenius-type behaviour and the activation energy of the relaxation process is quantified. The activation energy within the cartilage is approximately 11 ± 2 kJ mol−1 with this notably being less than that for both pure water (16.6 ± 0.4 kJ mol−1) and the phosphate-buffered solution in which the cartilage was immersed (14.7 ± 1.0 kJ mol−1). It is shown that this activation energy increases as a function of depth in the cartilage. It is known that cartilage composition varies with depth, and hence, these results have been interpreted in terms of the structure within the cartilage tissue and the association of the water with the macromolecular constituents of the cartilage

Undulation instability in a bilayer lipid membrane due to electric field interaction with lipid dipoles

Bilayer lipid membranes [BLMs] are an essential component of all biological systems, forming a functional barrier for cells and organelles from the surrounding environment. The lipid molecules that form membranes contain both permanent and induced dipoles, and an electric field can induce the formation of pores when the transverse field is sufficiently strong (electroporation). Here, a phenomenological free energy is constructed to model the response of a BLM to a transverse static electric field. The model contains a continuum description of the membrane dipoles and a coupling between the headgroup dipoles and the membrane tilt. The membrane is found to become unstable through buckling modes, which are weakly coupled to thickness fluctuations in the membrane. The thickness fluctuations, along with the increase in interfacial area produced by membrane buckling, increase the probability of localized membrane breakdown, which may lead to pore formation. The instability is found to depend strongly on the strength of the coupling between the dipolar headgroups and the membrane tilt as well as the degree of dipolar ordering in the membrane.Comment: 29 pages 8 fig