Generalized model for IGC growth in aluminum alloys

A generalized brick wall model is developed to describe intergranular corrosion in Equi-axed AA7178-T6 and Wingskin AA7178-T6 aluminum alloys. The intergranular corrosion rate is highly related to grain size and shape. High strength aluminum alloys are often elongated and anisotropic, with the fastest nominal IGC growth rate in the longitudinal direction (L) or long transverse direction (T) and the slowest in the short transverse direction (S). We propose a three-way intersection model and use it to simulate the corrosion kinetics for each direction. With a proper combination of model parameters, the generalized IGC model provides a good fit to experimental data developed by the foil penetration technique.     

Social work and day care: a role looking for a profession

The profession's present role in day care is assessed through a review of the social work literature. This analysis suggests that the profession is not systematically involved enough in child care systems on a local or national basis. The author discusses why this is so, and suggests professional points of access for social workers interested in providing social services in different types of child care. In addition, it is recommended that more policy and programmatic emphases be put on providing social services to family day care homes, the care of children by their relatives, and for centers that serve ethnic minorities and disadvantaged families.I wish to thank Beatrice Saunders and Eleanor Brilliant for their help in writing this article.     

A Comparison of Address-Based Sampling (ABS) Versus Random-Digit Dialing (RDD) for General Population Surveys

Valid and reliable public health data are becoming more difficultto obtain through random-digit dial (RDD) telephone surveys.As a result, researchers are evaluating different survey designs(i.e., sampling frame and survey mode combinations) as complementsor alternatives to RDD. Traditionally, mail surveys of the generalpublic have been limited due to a lack of a complete samplingframe of households. Recent advances in electronic record keeping,however, have allowed researchers to develop a sample from aframe of addresses (e.g., the U.S. Postal Service Delivery SequenceFile, which appears to provide coverage which rivals or possiblyexceeds that obtained through RDD sampling methods). To testthe use of this frame for surveying adults aged 18 years andolder across a wide geographic area, a pilot study was conductedas part of the 2005 Behavioral Risk Factor Surveillance System(BRFSS). The pilot compared use of a traditional, RDD telephonesurvey methodology to an approach using a mail version of thequestionnaire completed by a random sample of households drawnfrom an address-based frame. The findings indicate that themail survey approach can achieve higher response rates in low-response-ratestates (<40%) than RDD (particularly when two mailings aresent). Additionally, the address frame with mail survey designprovides access to cell phone only households and offers costsavings over the telephone approach. The resulting sample, however,significantly overrepresents non-Hispanic whites and peoplewith higher levels of education.