Nano- and meso-measurement methods in the study of dielectrics

Measurements of the physical form and morphology of dielectrics and of their chemical characteristics and physical properties have become increasingly important at micron and sub-micron length scales. Such length scales are accessible by different forms of microscopy but scanning probe methods allow both chemical and physical measurements to be made, in addition to morphological and typographical imaging, at nanoscopic and mesoscopic length scales. These measurements are described in this paper with examples drawn from many areas of dielectric research and applications, including polymer morphology, surface and subsurface charge measurements along with the dynamics of charge-decay, surface potential and work function, microelectronics, ferroelectrics, photocharging, dielectric response and nanoscopic relaxation and nanoscopic Raman spectroscopy. The future of scanning probe methods for dielectric measurements is assured but more effort is required to both develop and consolidate this form of nano-metrology.     

The Imbrication Model for the integration of social services in a community

An innovative model for organising social services in a community, the Imbrication Model, is contrasted with two traditional models, the Entrepreneurial and the Umbrella Agency. The structural characteristics and dynamics of the three models are illustrated with actual case histories. Imbrication Model calls for the interlocking of personnel from several agencies, with the purpose of redirecting the dysfunctional interagency rivalry prevalent in the traditional models. Imbrications at all organisational levels--Board of Directors, Administrators and Staff--facilitate adoption of the superordinate goal of providing clients with the best services available, regardless of which particular agency delivers the service. Few observers of the current social service scene would challenge the statement that needs for service are unlimited and resources limited. In the USA the imbalance between needs and resources persists despite a decade of massive governmental programmes intended to alleviate social ills. Recent substantial cutbacks in federal funds, moreover are not likely to improve the situation. The resource shortage involves more than a limitation of funds. Deliverers of service and competent programme administrators are also on critically short supply. These shortages are more often than not exacerbated by a chronic spirit of competition among agencies and programmes at the local level. Three organizational models for the delivery and administration of social services, two conventional and one of more recent date, are examined in this article. The innovative model, which has been named the Imbrication Model, explicitly calls for redirecting interagency rivalry and competition. Its ambitious goal is to integrate the efforts of those attempting to meet a community's social service needs.     

Dietary energy restriction does not inhibit pancreatic carcinogenesis by N-nitrosobis-2-(oxopropyl)amine in the Syrian hamster

Dietary energy restriction was previously shown to be effective in preventing a wide range of experimentally induced cancers. Studies were conducted to assess the influence on pancreatic carcinogenesis of dietary energy restrictions (reduced fat and carbohydrate) of 10%, 20% or 40% in comparison with control in Syrian hamsters treated with N-nitrosobis(2-oxopropyl)amine (BOP). Two carcinogenesis studies were conducted. One used a single treatment with 20 mg BOP/kg body weight and followed hamsters for 102 weeks following treatment, and the other used three weekly treatments of 20 mg BOP/kg body weight and followed hamsters for 45 weeks after treatment. Hamsters were fed control or energy restricted diet beginning the week following the last BOP treatment. Pancreatic carcinomas were induced in 9-18% of the hamsters in the first experiment and in 59-66% of the animals in the second. Dietary energy restriction did not influence carcinoma incidence in either study, and in the second experiment the multiplicity of tumors was higher in the 40% energy restriction (ER) group than in control hamsters. Plasma corticosterone was suppressed by BOP treatment, particularly in the 20% and 40% ER hamsters in the second experiment, and diet or BOP treatment did not significantly alter plasma cortisol. Pancreatic protein kinase Czeta measured by Western blot was highest in the cytosol and particulate fractions of the 40% ER hamsters in the first experiment. These results indicate that dietary energy restriction is not effective in the prevention of BOP induced pancreatic carcinogenesis in the Syrian hamster.     

Positive DC Coronas with Arbitrary Outer-Conductor Geometries

The two-dimensional Poisson's equation for a positive dc corona in air with arbitrarily-shaped boundaries-is solved using numerical methods. Solutions to the problem give the potential, electric field, space charge density, ion trajectories, and current density for all points in the field of interest, and the corona current flowing to any boundary. Good agreement is obtained between the theory and experimental measurements.