Shop-floor bargaining and the struggle for job control in the British automobile and aerospace industries 1950-1982

In the UK automobile and aerospace industries, the struggle over job control and rewards for labour expended in the production process was particularly intense in the period of steady economic growth, high and stable employment, and low inflation, following the Second World War. This struggle reached its zenith during a phase of increasing output in the 1950s and early 1960s. By the late 1960s, however, as wages and unemployment began to rise and the rate of growth slowed there was a discernible shift in management industrial relations strategy and efforts by government to curb the authority and influence of shop-stewards. Despite disparities both between and within these respective industries, particularly the higher skill levels required by the aerospace sector, common experiences of the transformation of labour conditions of work are noticeable. In mapping some key historical struggles of automobile and aerospace workers against management forms of authority and control, it should be possible to distinguish the critical dynamics prevalent in both industries. Knowledge of the trajectory of labour relations and the pattern and character of conflict is critical to understanding and accounting for continuity and change in the social relations of production

Arc Phenomena in low-voltage current limiting circuit breakers

Circuit breakers are an important safety feature in most electrical circuits, and they act to prevent excessive currents caused by short circuits, for example. Low-voltage current limiting circuit breakers are activated by a trip solenoid when a critical current is exceeded. The solenoid moves two contacts apart to break the circuit. However, as soon as the contacts are separated an electric arc forms between them, ionising the air in the gap, increasing the electrical conductivity of air to that of the hot plasma that forms, and current continues to flow. The currents involved may be as large as 80,000 amperes. Critical to the success of the circuit breaker is that it is designed to cause the arc to move away from the contacts, into a widening wedge-shaped region. This lengthens the arc, and then moves it onto a series of separator plates called an arc divider or splitter. The arc divider raises the voltage required to sustain the arcs across it, above the voltage that is provided across the breaker, so that the circuit is broken and the arcing dies away. This entire process occurs in milliseconds, and is usually associated with a sound like an explosion and a bright ash from the arc. Parts of the contacts and the arc divider may melt and/or vapourise. The question to be addressed by the Study Group was to mathematically model the arc motion and extinction, with the overall aim of an improved understanding that would help the design of a better circuit breaker. Further discussion indicated that two key mechanisms are believed to contribute to the movement of the arc away from the contacts, one being self-magnetism (where the magnetic field associated with the arc and surrounding circuitry acts to push it towards the arc divider), and the other being air flow (where expansion of air combined with the design of the chamber enclosing the arc causes gas flow towards the arc divider). Further discussion also indicated that a key aspect of circuit breaker design was that it is desirable to have as fast a quenching of the arc as possible, that is, the faster the circuit breaker can act to stop current flow, the better. The relative importance of magnetic and air pressure effects on quenching speed is of central interest to circuit design

Economic Outlook for Representative Cotton Farms Given the August 2005 FAPRI/AFPC Baseline

The Agricultural and Food Policy Center (AFPC) at Texas A&M University develops and maintains data to simulate eighteen representative cotton operations in major production areas of seven states. The chief purpose of this analysis is to project those farms’ economic viability for 2005 through 2009. The data necessary to simulate the economic activity of these operations is developed through ongoing cooperation with panels of agricultural producers in each of these states. The Food and Agricultural Policy Research Institute (FAPRI) provided projected prices, policy variables, and input inflation rates in their August 2005 Baseline. Under the August 2005 Baseline, only the moderately sized Tennessee cotton farm (TNC1900) and Louisiana cotton farm (LAC2640) are considered in good liquidity condition (less than a 25 percent chance of negative ending cash during 2005-2009). Five cotton farms (TXSP3745, TXRP2500, TXMC3500, TXCB1850, and TNC4050) have between a 25 percent and a 50 percent likelihood of negative ending cash. The remaining eleven cotton farms have greater than a 50 percent chance of negative ending cash. Additionally, TNC1900 is the only farm in the set considered in good equity position (less than a 25 percent chance of decreasing real net worth during 2005-2009). Three cotton farms (TXRP2500, TXMC3500, and TXCB1850) have between a 25 percent and 50 percent likelihood of losing real net worth, and the remaining fourteen cotton farms have greater than a 50 percent probability of decreasing real net worth.Agribusiness, Agricultural and Food Policy, Crop Production/Industries,

Counterion Condensation on Spheres in the Salt-free Limit

A highly-charged spherical colloid in a salt-free environment exerts such a powerful attraction on its counterions that a certain fraction condenses onto the surface of a particle. The degree of condensation depends on the curvature of the surface. So, for instance, condensation is triggered on a highly-charged sphere only if the radius exceeds a certain critical radius \collrad^{*}. \collrad^{*} is expected to be a simple function of the volume fraction of particles. To test these predictions, we prepare spherical particles which contain a covalently-bound ionic liquid, which is engineered to dissociate efficiently in a low-dielectric medium. By varying the proportion of ionic liquid to monomer we synthesise nonpolar dispersions of highly-charged spheres which contain essentially no free co-ions. The only ions in the system are counterions generated by the dissociation of surface-bound groups. We study the electrophoretic mobility of this salt-free system as a function of the colloid volume fraction, the particle radius, and the bare charge density and find evidence for extensive counterion condensation. At low electric fields, we observe excellent agreement with Poisson-Boltzmann predictions for counterion condensation on spheres. At high electric fields however, where ion advection is dominant, the electrophoretic mobility is enhanced significantly which we attribute to hydrodynamic stripping of the condensed layer of counterions from the surface of the particle.Comment: 13 pages, 9 figures and two table

Singular limit of Hele-Shaw flow and dispersive regularization of shock waves

We study a family of solutions to the Saffman-Taylor problem with zero surface tension at a critical regime. In this regime, the interface develops a thin singular finger. The flow of an isolated finger is given by the Whitham equations for the KdV integrable hierarchy. We show that the flow describing bubble break-off is identical to the Gurevich-Pitaevsky solution for regularization of shock waves in dispersive media. The method provides a scheme for the continuation of the flow through singularites.Comment: Some typos corrected, added journal referenc

Improved chemistry restraints for crystallographic refinement by integrating the Amber force field into Phenix.

The refinement of biomolecular crystallographic models relies on geometric restraints to help to address the paucity of experimental data typical in these experiments. Limitations in these restraints can degrade the quality of the resulting atomic models. Here, an integration of the full all-atom Amber molecular-dynamics force field into Phenix crystallographic refinement is presented, which enables more complete modeling of biomolecular chemistry. The advantages of the force field include a carefully derived set of torsion-angle potentials, an extensive and flexible set of atom types, Lennard-Jones treatment of nonbonded interactions and a full treatment of crystalline electrostatics. The new combined method was tested against conventional geometry restraints for over 22 000 protein structures. Structures refined with the new method show substantially improved model quality. On average, Ramachandran and rotamer scores are somewhat better, clashscores and MolProbity scores are significantly improved, and the modeling of electrostatics leads to structures that exhibit more, and more correct, hydrogen bonds than those refined using traditional geometry restraints. In general it is found that model improvements are greatest at lower resolutions, prompting plans to add the Amber target function to real-space refinement for use in electron cryo-microscopy. This work opens the door to the future development of more advanced applications such as Amber-based ensemble refinement, quantum-mechanical representation of active sites and improved geometric restraints for simulated annealing