On soft gluon effects in deep-inelastic structure functions

The behaviour of the quark coefficient functions in deep-inelastic scattering is investigated for large values of the Bjorken variable x. By combining results of soft-gluon resummation and fixed-order calculations, we determine the coefficients of the four leading large-x logarithms, alpha_s^k [{ln(1-x)}^{2k-l}/(1-x)]_+, l = 1, ...4, to all orders in the strong coupling constant alpha_s. This result includes two more terms for the three-loop coefficient functions than previously specified in the literature. The effect of the fifth logarithmic contribution is approximately evaluated. The terms derived here are required, but also seem to be sufficient, for a reliable representation of the coefficient functions at large x.Comment: 10 pages, 3 figures, misprints in third line of eq. (15) correcte

Atmospheric Gaseous Sulfuric Acid Measurements:Implications for Aerosol Formation by Homogeneous Nucleation

This work is focused on the presentation and interpretation of measurements of gaseous sul- furic acid, which we have made at Hyytiälä (Finland) in the framework of the European pro- jects BACCI (Research Unit on Biosphere-Aerosol-Cloud-Climate-Interactions) and QUEST (Quantification of Aerosol Nucleation in the European Boundary Layer). These measurements were conducted using Chemical Ionization Mass Spectrometry (CIMS) and represent one of the few long-term gaseous sulfuric acid measurements. Sulfuric Acid is probably the key trigger of new particle formation by nucleation. On the basis of our sulfuric acid measu- rements the nucleation process was examined considering the aerosol size distributions which were simultaneously measured. The H2SO4 data were compared with particle and meteorological parameters in order to characterize conditions for nucleation. In the next step it was examined to what extent the number concentration of small particles depends on the sulfuric acid concentration. Previous theoretical and experimental investigations showed that new particle concentrations obey a linear or a quadratic dependence on the gaseous sulfuric acid concentration. Both dependencies were observed in this work which indicates that activation (linear) as well as kinetic nucleation theory (quadratic) can explain the formation of new particles in this region

A Note on Extrema of Linear Combinations of Elementary Symmetric Functions

This note provides a new approach to a result of Foregger and related earlier results by Keilson and Eberlein. Using quite different techniques, we prove a more general result from which the others follow easily. Finally, we argue that the proof given by Foregger is flawed.Comment: (v2) revision based on suggestions by refere

Prediction of service life of polymeric sealant compositions for fuel tanks in aerospace structures from measurements of viscoelastic properties Annual report

Prediction of service life of polymeric sealers for fuel tanks from viscoelastic measurement

Reconciling credibility and accountability: how expert bodies achieve credibility through accountability processes

Arguments about the legitimate role of expert bodies in Europe often centre on the following question: Does their independence help to make policies credible or should they be made democratically accountable to principals and stakeholders? This article claims this is a false dichotomy. It does so by arguing theoretically that credibility can be achieved through accountability processes. Then, drawing on exemplary case studies, this article identifies distinctive accountability processes for ensuring credibility: revisable competencies, deliberation over institutional design, and engagement in public justification. Credibility and accountability are thus not conflicting, but co-constitutive aims of delegation to expert bodies. The analysis provides European policy makers and others with a guide for thinking beyond the contrast between ‘democratic accountability’ and ‘independent credibility’