Perception control systems and hierarchies of such systems are described. Perception control system theory asserts that human beings adjust their actions to control their perceptions. Purposive individuals adjust their actions to counter variable circumstances that prevent their perceptions from matching their objectives. Collective action can occur when two or more purposive individuals generate similar objectives independently, or when they do so interdependently, or when they adopt them from a third party. This explanation addresses the most characteristic feature of human behavior in temporary gatherings (crowds): alternating and vaned sequences of individual and collective action. A simulation program is described that varies up to three separate sets of control systems (seeking a destination, avoiding collisions, and seeking the path of other individuals) for each of 1 to 255 individuals constituting a gathering. The program features are illustrated with successive panels of screen prints of the development of nine different sequences of individual and collective action observed repeatedly in field research on temporary gathenngs. Theoretical, research, and practical implications are noted. An appendix descnbes program parameters.Computer simulation provides another tool with which social scientists can represent and examine complex human actions. In this essay we report on a new theory and methodology for simulating purposive individual and collective action in crowds. Although we are not the first to simulate crowd behavior, our simulations offer some theoretical and methodological innovations to that specific area of inquiry and to the understanding of purposive human behavior in genera!.t First, we briefly indicate some of the advantages and limitations of computer simulation as a methodology for studying human actions. Second, we review the theoretical model of purposive action on which our simulations are based. Third, we briefly describe the computer program derived from that theoretical model

The previous low-energy electron diffraction (LEED) work of the author on coincidence lattices formed by chemisorbed monolayers is extended to include two new structures, one formed by oxygen and the other by CO, on the (100) face of Rh. These structures are analyzed and found to be coincidence lattices, that is, high-coverage structures which are out of step with the substrate lattice in particular crystallographic directions but come into coincidence with it every several substrate lattice positions. The oxygen structure forms a slightly distorted close-packed arrangement which is out of step in the Rh [11] direction by 1/7 of the Rh-Rh separation. The CO structure is out of step in the Rh [10] direction by ⅙ of the Rh face-centered unit cell. It is concluded that the coincidence lattice is a general type of chemisorbed structure and that contrary to the general presumption, and particularly for high-coverage structures, the chemisorbed species do not always reside in positions of simple coordination with respect to the substrate.

Stability of deflected-beam metal-insulator-metal tunneling cathodes under high acceleration voltage J. Vac. Sci. Technol. B 31, 042203 (2013) Simple Si (111) surface preparation by thin wafer cleavage J. Vac. Sci. Technol. A 31, 023201 (2013) Novel techniques for modifying microtube surfaces with various periodic structures ranging from nano to microscale J. Vac. Sci. Technol. B 31, 011806 (2013) Decomposition and phase transformation in TiCrAlN thin coatings J. Vac. Sci. Technol. A 30, 061506 (2012) Surface modification of gold-carbon nanotube nanohybrids under the influence of near-infrared laser exposure Sputtered tungsten (W) coatings were investigated as potential high temperature nanophotonic material to replace bulk refractory metal substrates. Of particular interest are materials and coatings for thermophotovoltaic high-temperature energy conversion applications. For such applications, high reflectance of the substrate in the infrared wavelength range is critical in order to reduce losses due to waste heat. Therefore, the reflectance of the sputtered W coatings was characterized and compared at different temperatures. In addition, the microstructural evolution of sputtered W coatings (1 and 5 lm thick) was investigated as a function of anneal temperature from room temperature to 1000 C. Using in situ x-ray diffraction analysis, the microstrain in the two samples was quantified, ranging from 0.33% to 0.18% for the 1 lm sample and 0.26% to 0.20% for the 5 lm sample, decreasing as the temperature increased. The grain growth could not be as clearly quantified due to the dominating presence of microstrain in both samples but was in the order of 20 to 80 nm for the 1 lm sample and 50 to 100 nm for the 5 lm sample, as deposited. Finally, the 5 lm thick layer was found to be rougher than the 1 lm thick layer, with a lower reflectance at all wavelengths. However, after annealing the 5 lm sample at 900 C for 1 h, its reflectance exceeded that of the 1 lm sample and approached that of bulk W found in literature. Overall, the results of this study suggest that thick coatings are a promising alternative to bulk substrates as a low cost, easily integrated platform for nanostructured devices for high-temperature applications, if the problem of delamination at high temperature can be overcome.

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