A new range of turbomolecular pumps based on a Compact Metal Spring Damper (CMSD) system is described. The CMSD is essentially a support mechanism for the lower mechanical bearing which takes the form of a three-armed radial leaf spring. The result is that the design allows for small radial movement but has very high axial stiffness. The impact the CMSD has on the design of a new drag stage is described as is the constant very low vibration signature. Pumps fitted with a CMSD achieve such low vibration without the need for high-speed balancing and are fully end-user serviceable.
A new range of turbomolecular pumps, nEXT, has been developed. This incorporates a new damping mechanism and pumping stage options. A new Siegbahn drag stage in combination with a regenerative mechanism are described in their combination with pure turbomolecular stages. Consequent increased backing pressures, high compression ratios and the facilitation of a boost port being used to create additional pumping capacity in the viscous flow regime will be described.
In this article, we address the question of how organizational practices are diffused within networks of practice. We do so by drawing on the results of an ethnographic study of the diffusion of a complex mental health care treatment modality - the Democratic Therapeutic Community - that involved the attempted spread of novel work practices within a professional network of psychiatrists and their associated multi-disciplinary teams at two new clinical sites. We orientate the study within the networks of practice (NOP) literature on the diffusion of new work practices, considering in particular the issue of organizational power, which has been neglected hitherto. After presenting our ethnographic material, we draw attention to the role of clinical ideology, derived from founders and upheld by new, local clinical leaders in the appropriation process. By bringing in a concern for organizational power, we add to the existing literature through stressing the importance of ideological power, in supplying collective meaning, and the influential role of founders as creators and 'institutionalizers' of underlying ideologies.
