This paper presents a mathematical model for a model-scale unmanned helicopter robot, with emphasis on the dynamics of the flybar. The interaction between the flybar and the main rotor blade is explained in detail; it is shown how the flapping of the flybar increases the stability of the helicopter robot as well as assists in its actuation. The model helicopter has a fast time-domain response due to its small size, and is inherently unstable. Therefore, most commercially available model helicopters use the flybar to augment stability and make it easier for a pilot to fly. Working from first principles and basic aerodynamics, the equations of motion for full six degree-of-freedom with flybar-degree of freedom are derived. System identification experiments and results are presented to verify the mathematical model structure and to identify model parameters such as inertias and aerodynamic constants.

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The rate of synthesis of secretory proteins increases significantly in rat parotid glands after stimulated discharge of stored proteins. How any difference in the amount of secretory protein discharge affects the rate of subsequent protein synthesis, and whether this post-secretory synthesis is regulated at the level of messenger RNA, was now examined. One group of rats was stimulated to secrete 97% of stored secretory proteins by an intraperitoneal injection of isoproterenol. The other group received a much smaller dose to induce the discharge of about 40% of the proteins. Despite this difference in secretion, the subsequent rates of total protein synthesis, as well as of amylase, were increased to about the same extent. The amylase messenger RNA (mRNA) was identified and quantified by hybridization with a 32P-labelled amylase complementary DNA (cDNA) probe. The amylase mRNA in stimulated and unstimulated rats was of the same molecular size (Northern blot analyses). The amount of amylase mRNA, determined by dot blot analyses, were also increased in stimulated rats, although this increase was not as great as that in the rate of amylase protein synthesis. The implications of this discrepancy concern the possibility that the mechanism of regulation of secretory protein synthesis in parotid glands is at the translational level.

Abstracl. An unu.sually large and old ameloblastoma. which revealed a diverse histological appearance, was studied by light and electron microscopy. In the tumor, the epithelial component formed several patterns in the collagenous stroma. The epithelial islands, consisting of tall columnar cells surrounding the inner core of stellate cells, mimicked the cells ofthe inner enamel epithelium and stellate reticulum. respectively, of the normal enamel organ. The uUrastructural appearances of the columnar cells, however, were only similar to those which are seen in undifferentiated preameloblasts. Areas of .squaiiious metaplasia were present, and these squamous cells were structurally similar to the cells at the base of the oral epithelium. Some epithelial cells containing numerous lipid granules and mitochondria formed a network of cords. The connective tissue stroma was made up of fibroblast-like cells which appear to be metabolically active. In addition, multinucleated giant cells were present in the connective tissue stroma near the epithelial component.