Effects of mastication on the distribution of molecular weights and on the mechanical properties of native and commercial dental gutta percha (trans-polyisoprene)

Mastication of gutta percha (trans-polyisoprene) resulted in the selective scission of molecules, producing a narrower distribution of lower molecular weights. The mechanical properties of the samples also underwent a significant change due to mastication. The greater the content of incompatible substances (salts and oxides) in commercial gutta percha. the more substantial were these effects. The atmosphere (air, N₂, O₂) in which the experiments were conducted yielded significantly different results. The decrease in molecular weight was far greater in an O₂ atmosphere than under a current of nitrogen or air, owing to the combination of double bonds with O₂.     

Connections to cerebellar cortex (Larsell's HVI) in the rabbit: A WGA-HRP study with implications for classical eyeblink conditioning.

Conditioned eyeblink responses are presumably learned in the cerebellum and relayed to motoneurons by way of the red nucleus. Projections from the red nucleus to cerebellar cortex (Larsell's lobule HVI) could be important for shaping temporally adaptive features of the conditioned response. Rabbits that had pipettes containing wheat germ agglutinated horseradish peroxidase (WGA-HRP) implanted unilaterally into HVI showed retrograde labeling of neurons within subregions of the contralateral red nucleus implicated in eyeblink conditioning by lesioning and recording studies. Retrogradely labeled neurons were also observed in the pontine nuclei, inferior olive, and spinal trigeminal nucleus pars oralis. Projections to HVI provide a possible neural substrate for implementing time-derivative computational models of learning in the cerebellum. Time-derivative models are capable of describing the timing and topography of conditioned responses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Control of a Batch Processing Machine Serving Compatible Job Families

We consider the control of a single batch processing machine with random arrivals, random processing times, and compatible job families (jobs from different families may be processed together in the same batch, with the processing time distribution of the entire batch determined by the job family in the batch having the greatest expected processing time). The objective is to minimize the long-run average time that jobs spend in the system. We present properties possessed by the optimal policies and discuss the structure of these policies. We next develop a simple heuristic scheduling policy to control the machine. Simulation results are provided to demonstrate the effectiveness of our heuristic over a wide range of problem instances.     

Improved quality of continuous flow manufacturing through the combination of statistical process control and conventional computer process control

This paper represents a portion of the evaluation of the use of Statistical Process Control within the realm of Conventional Computer Process Control. Various control charts commonly utilized in continuous processes are evaluated when subjected to process disturbances typical of continuous processes. The control charts considered are the Moving Average and Moving Range Chart combination, the Individual and Moving Range Chart combination, and the Exponentially Weighted moving Average Chart. The types of process disturbances considered are unit step and linear trend disturbances to the process average. The evaluation is based on the determination of the Average Run Lengths (ARLs) resulting from computer simulations.     

Current gasket standards development in Europe

There are a large number of standards concerned with gasketed joints in the UK that are derived from the applications and practice of different industries. Many other countries also have equivalent standards. John Hoyes, technical director of Flexitallic and chairman of the British Standards Committee concerned with gaskets describes the European initiatives to rationalize the standards and improve the technical basis by which they will lead a user to select the joint design and material.