The stochastic control of process capability indices

In manufacturing science, process capability indices play a role analogous to economic indices in government statistics. The existing capability indices are passive devices whose main role is to retroactively monitor process capability. The have been developed under the restrictive assumption of process stability, and the procedures for using them are based on ad hoc rules. Using the normative point of view for decision making, it can be shown that some of the indices are, at best, convoluted special cases of a more general strategy; they can be justified only under special assumptions, and the manner in which they are currently used could lead to incoherent actions. The available process capability indices should therefore be abandoned and replaced by procedures that are normative, and also proactive with respect to both, prediction and control. An approach towards achieving this goal is proposed. Research Sponsored by The National Institute of Standards and Technology Gaithersburg, Maryland 20899-0001 (Under Purchase Order No. 43NANB610868), The U.S. Army Research Office Grant DAAG-55-97-1-0323, and The Air Force Office of Scientific Research Grant AFOSR-F-49620-95-0107     

Cholesterol mobilization and regression of atheroma in cholesterol-fed rabbits induced by large unilamellar vesicles

The antiatherogenic properties of repeated injections of egg phosphatidylcholine large unilamellar vesicles (LUVs) of 100 nm diameter were tested in an experimental model for atherosclerosis. Forty eight rabbits were divided into two diet groups fed standard rabbit chow or fed a cholesterol-enriched diet (0.5% by weight) to induce the formation of atherosclerotic lesions. Prior to the initiation of LUV therapy, the cholesterol diet was ceased and all animals were returned to standard rabbit chow. The treatment protocol consisted of a total of 10 bolus injections of vesicles, at a phospholipid dose of 300 mg/kg body weight or the equivalent volume of saline, with one injection given to each animal every 10 days. LUV injections brought about a large movement of cholesterol into the blood pool and resulted in a significant reduction in the cholesterol content as well as the degree of surface plaque involvement of aortic tissue in atherosclerotic animals. Most notably, the thoracic aorta of LUV-treated animals exhibited a 48% reduction in tissue cholesterol content per gram of protein compared to saline-treated controls. Histochemical analyses revealed that aortas from animals receiving the repeated injections of LUVs displayed less cholesterol deposits in lesions, and a moderate reduction in intimal-to-medial thickness. This regression of atheroma, induced by LUV therapy, was observed even though animals possessed persistent elevated plasma cholesterol levels after the cholesterol-enriched diet was ceased. These results suggest that repeated injections of LUVs, working with endogenous HDL, may be a useful therapy in the management of atherosclerosis.     

Time, technology and groups: An integration

This paper summarizes main findings of the five empirical papers in this issue, and discusses certain themes that connect them.     

Decentralized suboptimal load-frequency control of a hydro-thermal power system using the state variable model

State space modelling and synthesis of decentralized suboptimal load-frequency control for hydro-thermal power systems are described in this paper. The state space models are derived by the partial fraction technique for reheat steam turbines, hydro turbines and hydro governors having numerator dynamics. Decentralized suboptimal load-frequency controls are synthesized by using the method of minimum error excitation and their performance is analysed as a function of tie-line power level. It is shown that the suboptimal control with feedback of some, but not all, of the remote area state variables is a feasible alternative to the optimal control, whereas local control without feedback of any remote state variable is inadequate for stabilizing the system.     

Formation of stable Langmuir-Blodgett multilayers from oxiran carboxylic acids

Long-chain carboxylic acids, having oxiran groups at various positions along the chain, were synthesized and tested for their capacity to form ordered monolayers and multilayers. The oxiran groups were included because of their potential for polymerization during electron beam lithography. The hydrophilic nature of both the carboxylic acid and the oxiran groups in the same molecule afforded some difficulties in film formation, but one of these compounds provided stable monolayers and multilayers. Initial investigations have revealed that these multilayers are sensitive to electron beam polymerization.     

A study of the drawing behavior of polyvinylidene fluoride

The drawing behavior of different molecular weight PVDF grades has been investigated over the temperature range 140–160°C, with particular reference to the production of material with enhanced mechanical and electrical properties. Lower molecular weight grades, which have been subjected to a slow-cooled rather than a quenched moulding procedure yield higher Young's moduli when drawn to a given draw ratio. X-ray diffraction measurements have demonstrated that the crystalline regions of specimens drawn to high draw ratios under these conditions consist predominantly of the piezo- and pyroelectric form I phase. The relationship between the proportion of from I phase and the final drawing stress has been shown to be unique over the temperature range investigated, irrespective of molecular weight and thermal processing history.     

Increasing xylazine dose-enhanced anesthetic properties of telazol-xylazine combination in swine

We evaluated combinations of telazol, ketamine, and xylazine (TKX), telazol and xylazine (TX), telazol, xylazine, and xylazine (T2X), and ketamine and xylazine (KX) for chemical restraint and anesthesia induction in swine. Forty healthy mixed-breed pigs were randomly assigned to the four treatment groups with 10 pigs in each group. For TKX, TX, and T2X combinations, anesthetics were premixed by adding xylazine and ketamine, sterile water and xylazine, or xylazine alone directly into the telazol vial. For KX, anesthetic agents were drawn up separately, then mixed in the same syringe immediately before injection. All anesthetics were given as a single intramuscular injection. All four anesthetic combinations induced a rapid onset of sternal recumbency within 1.55 +/- 0.5 min and lateral recumbency within 2.27 +/- 0.6 min in pigs after intramuscular injection. There was no significant difference among treatments in these regards. The T2X combination induced a significantly longer duration of analgesia than did either TKX, TX, or KX. The T2X combination also induced a significantly longer duration of tolerance for endotracheal intubation and duration of lateral recumbency. Heart and respiratory rates were not significantly different among the four treatment groups. Vomiting was not observed in any of the treated pigs throughout the procedure. Recovery quality and duration from time of drug administration to recovery of pig walking unassisted were similar in three treatment groups but was shorter in KX-treated pigs. We concluded that all four anesthetic combinations were suitable for chemical restraint but that only TKX, TX, and T2X were suitable for anesthesia induction in pigs.(ABSTRACT TRUNCATED AT 250 WORDS)     

There is more to pain measurement in children than "ouch".

Describes the advances of pain measurement in children. There are excellent self report measures of pain for children over the age of about 5 yrs. There are both broadband and fine-grained behavioral measures that have been extensively studied. Among the fine-grained measures, facial action scales appear to be most sensitive. Broadband behavioral measures have been shown to be valid and sensitive for short, sharp pain and for pain in the recovery room in infants and children. There is evidence that these measures habituate when a child is in pain for several hours. Some measures are not specific to pain and may also reflect anxiety and depression. Although the progress has been impressive, there are significant deficiencies in the measurement of longer term pain when self report measures cannot be used. There are significant economic and political barriers to adequate pain measurement that are as important as technical problems. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)