The behaviour of granular material in pure shear, direct shear and simple shear

In biaxial compression tests, the stress calculations based on boundary information underestimate the principal stresses leading to a significant overestimation of the shear strength. In direct shear tests, the shear strain becomes highly concentrated in the mid-plane of the sample during the test. Although the stress distribution within the specimen is heterogeneous, the evolution of the stress ratio inside the shear band is similar to that inferred from the boundary force calculations. It is also demonstrated that the dilatancy in the shear band significantly exceeds that implied from the boundary displacements. In simple shear tests, the stresses acting on the wall boundaries do not reflect the internal state of stress but merely provide information about the average mobilised wall friction. It is demonstrated that the results are sensitive to the initial stress state defined by K0 = sh/sv. For all cases, non-coaxiality of the principal stress and strain-rate directions is examined and the corresponding flow rule is identified. Periodic cell simulations have been used to examine biaxial compression for a wide range of initial packing densities. Both constant volume and constant mean stress tests have been simulated. The characteristic behaviour at both the macroscopic and microscopic scales is determined by whether or not the system percolates (enduring connectivity is established in all directions). The transition from non-percolating to percolating systems is characterised by transitional behaviour of internal variables and corresponds to an elastic percolation threshold, which correlates well with the establishment of a mechanical coordination number of ca. 3.0. Strong correlations are found between macroscopic and internal variables at the critical state.

Privatisation, state ownership and productivity:evidence from China

This paper examines the relationship between the transfer of ownership between the public and private sectors of Chinese industry, and its impacts on performance. We link ownership changes to productivity growth, and demonstrate that privatisation contributes significantly. We offer an extension that is generally ignored in the literature, in looking at firms that are taken back into state ownership, and evaluating the productivity growth effects of this. Further, we highlight the well-understood simultaneity problems, and demonstrate the hazard of ignoring the issue by comparing various estimators, including the modified control function approach. In general, the results stress the importance of allowing for such endogeneity when evaluating the productivity effects of ownership change.

Governance in contemporary Germany:the semisovereign State revisited

Throughout the 1970s and 1980s, West Germany was considered to be one of the world’s most successful economic and political systems. In his seminal 1987 analysis of West Germany’s ‘semisovereign’ system of governance, Peter Katzenstein attributed this success to a combination of a fragmented polity, consensus politics and incremental policy changes. However, unification in 1990 has both changed Germany’s institutional configuration and created economic and social challenges on a huge scale. This volume therefore asks whether semisovereignty still exists in contemporary Germany and, crucially, whether it remains an asset in terms of addressing these challenges. By shadowing and building on the original study, an eminent team of British, German and American scholars analyses institutional changes and the resulting policy developments in key sectors, with Peter Katzenstein himself providing the conclusion. Together, the chapters provide a landmark assessment of the outcomes produced by one of the world’s most important countries. Contents: 1. Introduction: semisovereignty challenged Simon Green and William E. Paterson; 2. Institutional transfer: can semisovereignty be transferred? The political economy of Eastern Germany Wade Jacoby; 3. Political parties Thomas Saalfeld; 4. Federalism: the new territorialism Charlie Jeffery; 5. Shock-absorbers under stress. Parapublic institutions and the double challenges of German unification and European integration Andreas Busch; 6. Economic policy management: catastrophic equilibrium, tipping points and crisis interventions Kenneth Dyson; 7. Industrial relations: from state weakness as strength to state weakness as weakness. Welfare corporatism and the private use of the public interest Wolfgang Streeck; 8. Social policy: crisis and transformation Roland Czada; 9. Immigration and integration policy: between incrementalism and non-decisions Simon Green; 10. Environmental policy: the law of diminishing returns? Charles Lees; 11. Administrative reform Kluas H. Goetz; 12. European policy-making: between associated sovereignty and semisovereignty William E. Paterson; 13. Conclusion: semisovereignty in United Germany Peter J. Katzenstein.

Illness perceptions predict reassurance following a negative exercise stress testing result

Many patients are not reassured after receiving normal results following cardiac investigations. While previous studies have shown anxiety to be a contributing factor, little research has investigated the influence of patients’ illness perceptions on reassurance. In this study we investigated whether illness perceptions predicted patients’ reassurance following normal exercise stress test results. Sixty-two chest pain patients without prior diagnosed cardiac pathology completed questionnaires assessing anxiety and illness perceptions prior to exercise stress testing. Patients completed a reassurance questionnaire immediately following their appointment and again one month later. Illness perceptions (consequences, timeline, identity, illness concern, and emotional effect) but not anxiety, significantly predicted reassurance immediately following testing. We found both state anxiety and illness perceptions to predict reassurance one month later. After controlling for anxiety, longer timeline and lower treatment control beliefs predicted lower reassurance. The results suggest that an intervention targeting patients who have high anxiety and negative illness perceptions prior to testing may improve reassurance and decrease disability and the subsequent use of medical care.

Measurement of residual stress by load and depth sensing indentation with spherical indenters

A new experimental technique is presented for making measurements of biaxial residual stress using load and depth sensing indentation (nanoindentation). The technique is based on spherical indentation, which, in certain deformation regimes, can be much more sensitive to residual stress than indentation with sharp pyramidal indenters like the Berkovich. Two different methods of analysis were developed: one requiring an independent measure of the material's yield strength and the other a reference specimen in the unstressed state or other known reference condition. Experiments conducted on aluminum alloys to which controlled biaxial bending stresses were applied showed that the methods are capable of measuring the residual stress to within 10-20% of the specimen yield stress. Because the methods do not require imaging of the hardness impressions, they are potentially useful for making localized measurements of residual stress, as in thin films or small volumes, or for characterization of point-to-point spatial variations of the surface stress.

Intracellular redox state modulates the T cell surface proteome – relevance to ageing

During ageing an altered redox balance has been observed in both intracellular and extracellular compartments, primarily due to glutathione depletion and metabolic stress. Maintaining redox homeostasis is important for controlling proliferation and apoptosis in response to specific stimuli for a variety of cells. For T cells, the ability to generate specific response to antigen is dependent on the oxidation state of cell surface and cytoplasmic protein-thiols. Here we describe the effects of depleting intracellular glutathione concentration for T cell exofacial expression of thioredoxin 1 and IL-2 production, and have determined the distribution of Trx1 with ageing. Using buthionine sulfoximine to deplete intracellular glutathione in Jurkat T cells we show using Western blotting that cell surface thioredoxin-1 is lowered and that the response to the lectin phytohaemagglutinin measured by ELISA as IL-2 production is also decreased. Using flow cytometry we show that the distribution of Trx1 on primary CD4+ T cells is age-dependent, with lower surface Trx1 expression and greater variability of surface expression observed with age. Together these data suggest that a relationship exists between the intracellular redox compartment and exofacial surface. Redox imbalance may be important for impaired T cell function during ageing.