CREATIVITY AND SOFTWARE DESIGN

Formal processes are increasingly recommended for those who build software. However, an analysis of the methods used by top software designers shows that cognitive, creative processes—in some ways the polar opposite of formal processes—are closer to the essence of the design task. Further analysis of the work of top designers exposes additional facts about design that challenge the traditional, textbook views. The implications of these findings to software builders are explored in this article.     

Unifying model for associative thickener influences on waterborne coatings: II. Competitive adsorption of nonionic surfactants and HEUR thickeners on titanium dioxide pretreated with inorganic stabilizers and organic oligomeric dispersants

Size exclusion chromatography in tandem with UV absorbance of the surfactant is used to separate and quantify the amount of nonionic surfactant and model hydrophobically modified ethoxylated urethane (HEUR) thickeners adsorbed on different organic oligomeric polyacid, metal oxide-treated TiO₂ surfaces. The isoelectric point imposed on TiO₂ by the metal oxide surface treatment determines the amount of organic dispersant adsorbed. The size of the α-olefin on the maleic acid dispersant is also important in the adsorption of the dispersant. The size of the α-olefin on the organic acid dispersant, in turn, determines the amount of surfactant and HEUR thickener adsorbed. The surfactant, unlike the HEUR thickener, exhibits a dependence on the metal oxide treatment in neutral media, independent in several aspects of the amount of organic dispersant adsorbed. The adsorption dependence of HEUR thickeners and nonionic surfactant on the hydrophobe size of the HEUR is discussed. Presented at the 69th Annual Meeting of the Federation of Societies for Coatings Technology, on October 23, 1996 in Chicago, IL Polymers and Coatings Dept., Dunbar Hall, Fargo, ND 58105. Chestnut Run, Building 709, Wilmington, DE 19898.     

Ruby masers for maximum G/Top

The Deep-Space Network (DSN) includes world-wide networks of 26-, 34- and 70-m antennas in Australia, Spain, and the USA. Ruby masers are used on the 34and 70-m antennas to maximize the system operating noise temperature and thereby maximize the DSN receiving system figure of merit, antenna gain divided by system operating noise temperature. These systems are used for deep-space telecommunications, solar system radar, and radio astronomy. Cavity, traveling-wave, and reflected-wave maser designs and performance characteristics from 960 MHz to 34 GHz are summarized. Effective noise temperatures of ruby masers are addressed with emphasis on a 33.68-GHz maser where quantum noise is a major source of noise     

Dark time yellowing of white rigid vinyl outdoor weatherable compounds

White PVC siding which has been exposed to sunlight will after removal from the sunlight develop a darker color (yellow-brown). The longer this sample remains unexposed to sunlight the greater the color development. Testing has indicated that one or more photochemical mechanisms are occurring during this color development. A sample which appears yellow upon arrival at the home location after outside exposure can be re-whitened by re-exposing the sample to sunlight. Drastic color change will occur within a short period of time, usually less than 72 hours. This sample will have attained its white color with little or no yellowing visible when an original unexposed sample is held next to it. Testing conducted at an Arizona test site has confirmed these theories. Six months and one year weathered white siding samples, when measured at the test site, both experimental and commercial, showed that when the weathered samples are removed from the test racks and tristimulus values are measured daily, marked color changes occur rapidly. This paper addresses data which indicate that color development does occur but only in the very thin surface (5 to 10 micron layer) of the weathered samples. If these samples are washed and the abrasive action is sufficient to remove the surface layer, color development will no longer occur during non-exposure to sunlight.     

Evidence for strain specificity in cytotoxic T-lymphocyte-mediated, major histocompatibility complex class I-dependent killing of Theileria annulata-infected cells

Cattle immunised against Theileria annulata with one parasite strain have been found to be immune to re-challenge with different strains of the parasite. However, recent evidence of apparent strain specificity has been documented in cattle immunised with attenuated parasite-infected cells. In this study the strain specificity of major histocompatibility complex class I-restricted cytotoxic T-lymphocytes (CTL), a major anti-parasite effector mechanism, was examined. CTL generated following challenge with the Hissar (Indian) strain effectively lysed autologous cells infected with this strain of the parasite. However, CTL were less effective against cells infected with the Gharb (Moroccan) strain and showed virtually no reactivity against the Ankara (Turkish) strain, providing the first direct evidence for strain specificity in immune responses against T. annulata.     

Real-time checkout: The ‘source error first’ approach

This paper proposes some improvements to the archaic methodologies currently used for checkout of real-time software. The emphasis is placed on removing errors from the computer program source code in the host computer environment, and deferring target computer checkout until those errors have been largely removed. Specific tools and techniques to make this possible are described. This improvement is seen to be risk-free and to reduce cost. It is, however, controversial.