Monitoring performance of nucleic acid-based diagnostic measurement system users by EQA

External quality assurance (EQA) programmes allow a laboratory to monitor independently its performance and provide feedback to identify and investigate potential areas of concern. However, both the definition of appropriate ‘performance indicators’ and their statistical analysis vary across EQA providers. Typically, performance scores have an unknown statistical distribution and hence arbitrary thresholds are used to measure performance. In this paper, we introduce a scoring system based on well-known statistical principles. The system is simple, flexible and easy to interpret. It can be used to measure performance for single samples or across a panel so providing useful and meaningful information to participants in EQA programmes. The score is illustrated using the 2005 QCMD Hepatitis B Virus Proficiency programme.     

Boundary scattering in the principal chiral model

An introduction to our recent work (hep-th/0104212) on the (G ×G-invariant) principal chiral model with boundary is presented. We found that both classically integrable boundary conditions and quantum boundary is presentedS-matrices were classified by the symmetric spacesG/H. Presented at the 10th International Colloquium on Quantum Groups: “Quantum Groups and Integrable Systems”, Prague, 21–23 June 2001.     

The application of capillary SFC,packed column SFC,and capillary SFC-MS in the analysis of controlled drugs

Multi–component mixtures of controlled drugs, drug impurities, and adulterants have been analyzed by capillary SFC-FID, packed column SFC-UV, and capillary SFC-MS. Isocratic packed column SFC has been performed with binary and ternary mobile phases using a single syringe pump. The combination of capillary SFC and double focusing MS is described with reference to MS source pressures and the spectra obtained. The use of negative temperature programming in SFC is described.     

Acid-triggered transformation of diortho ester phosphocholine liposome

The use of pH-sensitive liposomes for acid-triggered site-specific drug delivery is one of the more promising approaches to improve the therapeutic index of drugs. Here, we report the synthesis, assembly, and hydrolysis of the first ortho ester phosphocholine (OEPC). The acid hydrolysis of OEPC liposomes consists of a lag phase and a burst phase. The lag time is pH-dependent-the lower the pH, the shorter the time. Upon acid hydrolysis, the OEPC liposomes were transformed into leaky metastable vesicles that rapidly collapsed in the presence of albumin. OEPC, when formulated with cationic lipid, significantly enhanced the transfection efficiency compared with that of the pH-insensitive formulation.     

Boundary integrability of nonlinear sigma models

We describe recent work on the classical integrability of the principal chiral model and general sigma models with boundaries in (compact) symmetric spaces.Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 142, No. 2, pp. 322–328, February, 2005.     

Kinetic resolution of allylic alcohols using a chiral phosphine catalyst

[reaction: see text] The kinetic resolution of racemic allylic alcohols 3, 6, and 12--17 has been explored using the PBO catalyst 7 for activation of isobutyric anhydride. Trisubstituted allylic alcohols (12--15; 17) are the best substrates and react with an enantioselectivity of s = 32--82 at -40 degrees C.     

Probability on Graphs: Random Processes on Graphs and Lattices,by G. Grimmett

The 12 member states of the European high energy physics laboratory CERN are considering the construction of a huge new accelerator. This article outlines our understanding of the fundamental forces of nature and the subnuclear structure of matter, and describes the accelerator that will enable some of their mysteries to be explained.