Expanding the application of facial ceramic veneers

"Full veneers," restorations similar in depth to ceramic veneers but extending over the lingual or occlusal surface as well as the facial surface, are a conservative option to conventional crowns. They have been used successfully at the UCLA Center for Esthetic Dentistry for three years. Indications, technique and a patient study are presented.     

Euclidean controllable realizations of linear hereditary systems

A realization problem for a class of linear hereditary systems is formulated and state space representations are constructed from inputoutput relations. The resulting hereditary models are shown to be Euclidean controllable, and comparisons are made between these hereditary realizations and other recently developed theories.This research was supported in part by the Air Force Flight Dynamics Laboratory under grant AFOSR-77-3221.     

Perthes' disease treated by prolonged recumbency and femoral head containment: a long-term appraisal

The results of a long-term review of 102 hips in eighty-seven patients with Perthes' disease are described, the mean follow-up interval being seventeen years. All had been treated by an extremely rigorous conservative regime in which the patients were kept in hospital for an average period of twenty-six months, during which time they were confined to bed with the legs in wide abduction, first in traction and later in "broomstick" plasters to ensure "containment" of the femoral head. The patients were assessed by the joint clincial and radiological method described by Ratliff (1956). The results were very satisfactory, with only 2 per cent poor results and 10 per cent fair. The remaining 88 per cent were good. The radiological results at the end of treatment have also been compared with control series described by Catterall (1972) and with the osteotomy series of Lloyd-Roberts, Catterall and Salamon (1976). From this it appears that the described regime offers no benefit compared with the natural history in Catterall's Groups I and II, and in Group III the results were only marginally better than those following osteotomy. In Group IV cases, however, where the femoral head was totally involved, the benefit was important, and since these are the cases which carry the worst natural prognosis it is suggested that the use of the method described in such instances must be seriously considered in spite of its social disadvantages. The theoretical implications of the findings are considered, and it is concluded that the benefits of the method cannot be ascribed wholly to the application of the "containment" principle.     

A DSP-based mixed-signal waveform generator

As it currently stands, waveform generators are being employed in many diverse areas, such as radar applications, communication systems, simulation, and testing. There is considerable interest in exploring the beacon of opportunity posed by using digital signal processor (DSP)-based systems to replace costly and inadequate conventional waveform generators. The availability of high performance DSPs allows for the design of highly flexible equipment capable of real-time processing. The arbitrary waveform generator introduced in this paper consists of a DSP, a FIFO memory, a video palette, and a PC interface. A program running on the PC creates a digital representation of a waveform according to user parameters and sends it to the DSP's RAM. The DSP algorithmically converts the digital representation to a point-by-point representation of the desired analog signal. The data points are sent to the FIFO buffer, which latches the data to a video palette that serves a three-channel digital-to-analog converter. The system employs a high-speed serial port interface to communicate with a PC, to allow for readily programmed signals. In addition to the production of traditional signals, such as sinusoids and squarewaves, a mathematical tool known as splines is employed to aid in the development of customized arbitrary waveforms. Finally, a picture of our new device is presented in the paper.     

An adaptive production control system utilizing agent technology

Agents are intelligent software objects capable of reasoning about, and interacting with, their environment. This paper presents conceptual and prototypical models of an adaptive production control system based on agent technology. In the system presented both workpieces and resources are represented by agents. Supervisory agents are introduced as the production load on the resources increases and removed as the load decreases. These supervisory agents serve to balance the production load across resources and maximize overall throughput. Simulation studies are presented demonstrating improvements in throughput, resource utilization, and work-in-process inventories over systems invariant to production load.     

Texting While Driving: An Empirical Investigation of Students’ Attitudes and Behaviors

The distracting effects of texting while driving activity of young adults are receiving increasing attention. The findings indicate that individuals involved in texting while driving also engage in other risky behaviors. Furthermore, frequency of texting while driving appears to be related to several factors, including self-control, attitudes toward texting and responsible driving, and opinions of peers, but interestingly not with social responsibility. In conclusion, the frequency of texting while driving of young adults appears to be related to several factors, suggesting possible ways the frequency of texting while driving may be affected.