Trees of semi-simple algebras

To a tree of semi-simple algebras we associate a qurve (or formally smooth algebra) S. We introduce a Zariski- and etale quiver describing the finite dimensional representations of S. In particular, we show that all quotient varieties of the etale quiver have a natural Poisson structure induced by a double Poisson algebra structure on a certain universal localization of its path algebra. Explicit calculations are included for the group algebras of the arithmetic groups (P)SL2(Z) and GL2(Z) but the methods apply as well to congruence subgroups

Non-commutative covers and the modular group

We use non-commutative geometry to study the bulk of finite dimensional representations of the modular group SL(2,Z). We give specific 2n-parameter families of 6n-dimensional representations obtained from the quotient singularity C^2/Z_6

Corrigendum to: ‘Shy trout grow faster: do personality traits predict fitness of brown trout in the wild?’ by Bart Adriaenssens and Jörgen I. Johnsson. 22:135–143

No abstract available

Torsion/bending elements for dr modelling of tubular bearing structues

The paper presents a three degree of freedom formulation for the dynamic relaxation modelling of tubular bearing systems applied in arch supported membranes and closed hoop supported cable net bridging structures. For tubular arch structures the numerical modelling method has been validated against analytical and finite element models with span/rise ratios up to 20. Beyond this, and particularly as arches flatten under limit state loads the method becomes impractical. A revised process is given for the modelling when approaching failure states, and is applied and validated for the case of a very flexible arch supported membrane structure subject to snap through buckling. The paper also illustrates how the torsion/bending theory can be used to cover different closed hoop supporting systems, and the numerical modelling is applied to a multi-span bridging structure employing tubular hoops of various sizes and shapes around which spiral a prestressed cable network

Telomere length covaries with personality in wild brown trout

The prevalence of consistent among-individual differences in behaviour, or personality, makes adaptive sense if individuals differ in stable state variables that shift the balance between the costs and benefits of their behavioural decisions. These differences may give rise to both individual differences in, and covariance among, behaviours that influence an individual's exposure to risks. We here study the link between behaviour and a candidate state variable previously overlooked in the study of state-dependent personality variation: telomere length. Telomeres are the protective endcaps of chromosomes and their erosion with age is thought to play a crucial role in regulating organismal senescence and intrinsic lifespan. Following evidence that shorter telomeres may reduce the lifespan of animals in a wide range of taxa, we predict individuals with shorter telomeres to behave more boldly and aggressively. In order to test this, we measured telomere length and behaviour in wild juvenile brown trout (Salmo trutta). We found individuals with shorter fin telomeres to behave consistently more boldly and aggressively under controlled conditions in the laboratory. No such relationship was found with muscle telomere length 3–4 months after the behavioural assays. We suggest that telomere dynamics are an important factor integrating personality traits with other state variables thought to be important in the regulation of behaviour, such as metabolism, disease resistance and growth

Paracetamol metabolism in man

The absorption, metabolism and elimination of paracetamol was investigated in healthy subjects after therapeutic doses and also in patients with paracetamol overdosage, some of whom developed liver damage. Paracetamol disposition was also studied in relation to treatment with N-acetylcysteine (NAG),cysteamine and methionine, which were used to prevent paracetamol hepatotoxicity. Sensitive, specific and reproducible analytical methods were developed for the estimation of paracetamol and its sulphate, glucuronide, mercaoturic acid and cysteine conjugates in plasma and urine. These methods, which employed high-performance liquid chromatography, were significant improvements on existing procedures, especially in terms of simplicity and total assay times. N Following a therapeutic dose, absorption and metabolism of paracetamol was rapid and essentially complete. Paracetamol metabolism showed wide but reproducible individual variation. NAC had little appreciable effect on paracetamol elimination after a therapeutic dose but may have delayed absorption. The renal clearance of paracetamol was very low, indicating extensive renal tubular reabsorption whereas that of the sulphate and glucuronide conjugates was high, suggesting active tubular secretion. The mercapturic acid and cysteine conjugates were probably also actively secreted since they were not measureable ( <C 1 fig/ml) in plasma. Renal clearance of paracetamol and its conjugates wan not appreciably altered at high plasma concentrations following overdosage. Following overdosage, paracetamol elimination was rapid but prolonged relative to therapeutic dosage, particularly in patients who developed severe liver damage. The proportions of overall drug recovery excreted as the sulphate and glucuronide conjugates were lower and higher respectively, indicating saturation of sulphate conjugation. Also, the proportion excreted as the mercapturic acid and cysteine conjugates was increased in patients who developed severe liver damage. Early treatment of paracetamol overdosage with NAG was associated with reduced hepatotoxicity, enhanced formation of paracetamol sulphate, increased excretion of the mercapturic acid and cysteine conjugates and decreased plasma paracetamol half-life. Cysteamine treatment also resulted in reduced toxicity and enhanced formation of paracetamol sulphate but decreased excretion of the mercapturic acid and cysteine conjugates. Methionine had little appreciable effect on the metabolism of paracetamol and was the least effective treatment. NAG probably protects the liver by "unsaturating" sulphate conjugation and assisting removal of the toxic intermediate metabolite of paracetamol by direct conjugation and/or repleting hepatic glutathione. Cysteamine apparently inhibits the microsomal oxidation of paracetamol to its toxic intermediate metabolite