Development of an automated information retrieval system for the identification of antibiotics

The basic points in the development of a specialized computer information search system providing ientification of new antibiotics at early stages of their investigation are described. The system of coding the physico-chemical properties of the agents and the spectra of their antimicrobial activity presenting the substance in the information bank is developed. The task of identification is to find in the reference bank according to some specially organized keys such antibiotics which are identical or close by their properties to the substance being identified. Mini-computer of M-6000 type is used as the technical base of the information search system. Preliminary organization of the bank specified by the coding system markedly reduces the requirements to the computer operative memory.     

Deficient Ganglioside Biosynthesis: a novel human sphingolipidosis

An unusual lipid storage disese is chracterized by the accumulation of hematoside (Gms3) in the patient's liver and brain. In contrast to the other sphingoliidoses, the accumulation of Gm3 is not the result of a defective catabolic reaction, but is the first disorder caused by deficiency in ganglioside biosynthesis to be described in man.     

Π-representation: A clause representation for parallel search

An extension to the clause form of the first-order predicate calculus is described which facilitates parallel search operations. This notation, called parallel representation (Π-representation), permits the representation of sets of clauses as single “Π-clauses”. Extensions to the operations of unification, factoring, and resolution which apply to this notation are also described, and the advantages of Π-representation with respect to parallel searching, memory utilization, and the use of semantics are discussed.     

Origin of deficits in the flicker electroretinogram of the cone system in X-linked retinoschisis as derived from response nonlinearities

The aim of this study was to identify the origin of a high-frequency attenuation in the flicker electroretinogram (ERG) of patients with X-linked retinoschisis (XLRS) through an analysis of nonlinearities in the ERG response. The ERGs of six patients with XLRS and six age-similar control subjects were recorded in response to stimuli that consisted of pairs of sinusoids that had varying temporal frequencies and that differed by either 8 or 16 Hz. Compared with the control subjects, the patients with XLRS showed a significant reduction in the amplitude of the difference frequency to high-frequency stimuli that paralleled the high-frequency attenuation of their ERG response fundamental. This result indicates that a response attenuation at an initial linear filter, most likely photoreceptoral, was a major determinant of the reduced ERG amplitude of the XLRS patients at high temporal frequencies. Additional analyses of nonlinearities in the ERG responses provided evidence of a postreceptoral component to the flicker ERG deficits of the XLRS patients, as well.     

Formation of gas-saturated defects in titanium alloys during vacuum-arc remelting

The formation of gas-saturated defects in titanium alloys during vacuum-arc remelting is studied theoretically and experimentally. The defects of a metallurgical origin that were detected upon long-term monitoring of a commercial process of production are considered. The light-element contents are determined with a high-locality nuclear accelerator microanalysis technique. A theoretical model is developed to describe the dissolution of solid gas-saturated inclusions in liquid titanium; it is based on a mechanism of diffusion of modifying defects in melting. The critical parameters of defect sources (defect size, nitrogen concentration in a defect) at which defects do not dissolve in titanium upon melting are determined. The obtained dependence of the average light-element concentration in a defect on the defect size is explained.     

Changes in health care costs before and after smoking cessation.

Previous research on health care costs among former smokers suggests that quitters incur greater health care costs for up to 4 years after cessation compared with continuing smokers. However, little is known about the relationship between health care costs and utilization in the periods before as well as after cessation. The present study used a retrospective cohort design with automated health plan and primary data to examine the health care costs and clinical experiences before and after smoking cessation among former smokers compared with a sample of continuing smokers. Subjects were a random sample of adults (aged 25 and older) whose smoking status was identified by a physician during a primary care visit to the Group Health Cooperative (GHC), a nonprofit, integrated health care delivery system in western Washington state. Total direct health care costs among former smokers began to rise in the quarter prior to cessation and were significantly greater (p < .001) than those of continuing smokers in the quarter immediately following cessation. This difference dissipated within one quarter following cessation. We replicated the postquit cost spike among former smokers found by other research and showed that this spike dissipated within the first year postquit. Smoking cessation did not result in sustained cost increases among former smokers.     

A Comparison of Four Monte Carlo Methods for Estimating the Probability of s-t Connectedness

This paper describes and compares the performance of four alternative Monte Carlo sampling plans for estimating the probability that two nodes, s and t, are connected in an undirected network whose arcs fail randomly and independently. Models of this type are commonly used when computing the reliability of a system of randomly failing components. The first method, dagger sampling, relies for its advantage on inducing negative correlation between the outcomes of the replications in the sample. The second method, sequential destruction/construction exploits permutation properties of arc failures and successes. The third method uses easily determined bounds on the reliability probability to gain an advantage. The fourth approach enumerates all failure sets of the network to achieve its appeal. An example based on a 30-arc 20-node network illustrates the variance reducing features and the time and space needs of each sampling plan. Dagger sampling and sequential construction offer limited benefits when compared to the bounds and failure-sets methods. The failure-sets method performs best on the example for small failure probabilities. However, in general it offers no guarantee of a smaller variance than crude Monte Carlo and requires substantially more memory than the other methods. Moreover, this memory requirement can grow rapidly as the size of the network increases. By contrast, the bounds method guarantees a smaller variance than for crude Monte Carlo sampling and has modest memory requirements.