Finiteness in derived categories of local rings

New homotopy invariant finiteness conditions on modules over commutative rings are introduced, and their properties are studied systematically. A number of finiteness results for classical homological invariants like flat dimension, injective dimension, and Gorenstein dimension, are established. It is proved that these specialize to give results concerning modules over complete intersection local rings. A noteworthy feature is the use of techniques based on thick subcategories of derived categories.Comment: 40 pages. Minor revisions. To appear in Commentarii Math. Helvetic

Oil film measurement in polytetrafluoroethylene-faced thrust pad bearings for hydrogenerator applications

There is a growing trend in the replacement of the babbit facing in thrust pad bearings with a composite polytetrafluoroethylene (PTFE) surface layer. The PTFE-faced bearings have been shown to allow a greater specific pressure, reduce thermal crowning, and, in some cases, negate the need for an oil-lift (jacking) system. These designs of bearing require new methods for the measurement of oil film thickness both to assist in their development and for plant condition monitoring. In this work, an ultrasonic method of oil film measurement is evaluated for this purpose. An ultrasonic transducer is mounted on the back face of the thrust pad. Pulses are generated and transmitted through the pad material, bonding interlayer, and PTFE surface layer. The proportion of the wave that reflects back from the oil film layer is determined. This is then related to the oil film thickness using a series of calibration experiments and a spring stiffness model. In practice, the reflected signal is difficult to distinguish, in the time domain, from other internal reflections from the pad. Signals are compared with reflections when no oil film is present and processing is carried out in the frequency domain. Experiments have been performed on a full size PTFE-faced thrust pad destined for a hydroelectric power station turbine. The instrumented pad was installed in a test facility and subjected to a range of loading conditions both with and without oil lift. Although there were some problems with the robustness of the experimental procedure, oil films were successfully measured and used to study the effect of the oil-lift system on film formation. © IMechE 2006

DG algebras with exterior homology

We study differential graded algebras whose homology is an exterior algebra over a commutative ring R on a generator of degree n, and also certain types of differential modules over these DGAs. We obtain a complete classification when R is the integers, or the prime field of characteristic p>0, and n is greater than or equal to -1. The examples are unexpectedly interesting.Comment: 15 page

The social security rights of older international migrants in the European Union

Europe is now home to a significant and diverse population of older international migrants. Social and demographic changes have forced the issue of social security in old age onto the European social policy agenda in the last decade. In spite of an increased interest in the financial well-being of older people, many retired international migrants who are legally resident in the European Union face structured disadvantages. Four linked factors are of particular importance in shaping the pension rights and levels of financial provision available to individual older migrants: migration history, socio-legal status, past relationship to the paid labour market, and location within a particular EU Member State. Building on a typology of older migrants, the paper outlines the ways in which policy at both the European Union and Member State levels serves to diminish rather than enhance the social security rights of certain older international migrants

The Effects of a Disaster’s Onset on the Humanitarian Aid Supply Chain

Through the development of an illustrative model, this conceptual paper argues that the relative timeframe of the onset of a disaster – whether slow or sudden - is related to the form of the supply chain response of the humanitarian aid organization. Further, a proposed method for researching the interrelationship between the nature of a disaster and how it affects the formulation of the humanitarian aid supply chain is offered. Several contributing characteristics of humanitarian aid supply chains are identified and described within the context of the model. Finally, several potential avenues for future research are described including the efficiencies that may be realized from prepartnering among humanitarian aid organizations and suppliers. The ultimate goal of this research is to aid humanitarian aid organizations in fully realizing their goals through better understanding and administration of their supply chains

Pickled wheat is safe for sheep : feeding trial

FARMERS are often left with a surplus of pickled grain from seed wheat supplies. Many would like to feed this to their stock, but do not do so because they think there may be a risk of poisoning. This trial was designed to investigate the effects of feeding such grain to sheep

The influence of clearance on friction, lubrication and squeaking in large diameter metal-on-metal hip replacements

Large diameter metal-on-metal bearings (MOM) are becoming increasingly popular, addressing the needs of young and more active patients. Clinical data has shown excellent short-to-mid-term results, though incidences of transient squeaking have been noted between implantation and up to 2 years post-operative. Geometric design features, such as clearance, have been significant in influencing the performance of the bearings. Sets of MOM bearings with different clearances were investigated in this study using a hip friction simulator to examine the influence of clearance on friction, lubrication and squeaking. The friction factor was found to be highest in the largest clearance bearings under all test conditions. The incidence of squeaking was also highest in the large clearance bearings, with all bearings in this group squeaking throughout the study. A very low incidence of squeaking was observed in the other two clearance groups. The measured lubricating film was found to be lowest in the large clearance bearings. This study suggests that increasing the bearing clearance results in reduced lubricant film thickness, increased friction and an increased incidence of squeaking

Contestable adulthood: variability and disparity in markers for negotiating the transition to adulthood

Recent research has identified a discreet set of subjective markers that are seen as characterizing the transition to adulthood. The current study challenges this coherence by examining the disparity and variability in young people’s selection of such criteria. Four sentence-completion cues corresponding to four differentcontexts in which adult status might be contested were given to 156 British 16- to 17-year-olds. Their qualitative responses were analyzed to explore patterns whilst capturing some of their richness and diversity. An astonishing amount of variability emerged, both within and between cued contexts.The implications of this variability for how the transition to adulthood is experienced are explored. The argument is made that markers of the transition to adulthood are not merely reflective of the bio–psycho–social development of young people. Rather, adulthood here is seen as an essentially contested concept,located within the discursive interactional environment in which young people participate