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Biomedical subjects

L K Miller

Publications and source records attributed to L K Miller.

At least 217 records · Page 12Linked to original sources
PubMed1975

Effects of auditory stimulation upon non-nutritive sucking by premature infants.

Changes in non-nutritive sucking contingent upon presentation of an auditory stimulus previously found capable of eliciting heart-rate acceleration was investigated in a sample of 24 premature infants. Across 30 10-sec. presentations of the stimulus, only transient changes in sucking rate during the first 6 trials were observed, and these effects obtained primarily for those infants showing few abnormalities in their non-nutritive sucking behavior. These results were discussed as reflecting possible differences in infants' attention associated with sucking pathology and the dependence of psychological assessment upon the specific response index used.

Attention↗
PubMed1974

Nature of phi chi 174 linear DNA from a DNA ligase-defective host.

Linear DNAs have been prepared from phiX phage and from phiX RF II (double-stranded circular form of phiX DNA, formed during infection and nicked in one or both strands) molecules derived from infection at the restrictive temperature of Escherichia coli ts7, a host mutant with a temperature-sensitive DNA ligase activity. The linear DNA from these phages can be circularized by annealing with fragments of phiX RF DNA produced by the Haemophilus influenzae restriction nuclease. The circularization experiment indicated that the site of breakage of the linear phage DNAs is not unique nor confined to a particular region of the genome. These linear DNAs were less than 0.1% as infective as circular phage DNA. The linear, positive strand of late RF II DNA, however, is uniquely nicked in the region of the phiX genome corresponding to cistron A. Although a low level of infectivity is associated with the linear DNA derived from late RF II, this infectivity appears to be a result of the association of linear positive and linear negative strands during the infectivity assay.

Coliphages↗
PubMed1974

A procedure for maintaining student progress in a personalized university course.

Ten students in a personalized university course were given target dates for completing each of 26 lessons. The lessons could be completed before those dates, but not after. The first two failures to complete a lesson by the target date led to "warnings"; the next failure required the student to withdraw from the course. When each student's rate of lesson completion was compared with and without target dates, it was found that students completed an average of 1.0 lesson a day with the target-date contingency and 0.3 without it. Individual data indicated that most students did few or no lessons without the contingency. It was concluded that a target-date contingency is an effective method for maintaining student progress in personalized university courses.

Journal Article↗
PubMed1971

Nucleoside diphosphokinase activity associated with DNA polymerases.

Nucleoside diphosphokinase activity is present in highly purified preparations of DNA polymerase from Micrococcus luteus and Escherichia coli, and in a partially purified DNA polymerase from avian myeloblastosis virus. The activity is also observed in the protein fragment of molecular weight 76,000 that is produced by subtilisin cleavage of DNA polymerase I from E. coli. The NDP kinase activity in DNA polymerase preparations from M. luteus uses various ribo- and deoxyribonucleoside di- and triphosphates as substrates. The presence of this activity in preparations of DNA polymerase results in the apparent use of deoxyribonucleoside diphosphates as substrates for DNA synthesis, provided that some triphosphate is present to serve as a phosphate donor.

Adenosine Diphosphate↗
PubMed1970

Dinucleotides as products of an exonucleolytic activity association with the Micrococcus luteus DNA polymerase.

The partially purified DNA polymerase from Micrococcus luteus contains a low level of exonucleolytic activity. The enzyme preparation (1200-fold purified) contains approximately 100 times more polymerase than exonuclease activity. Both single- and double-stranded DNA are degraded at the same rate. The predominant products are dinucleoside diphosphates (d-pXpY); mononucleotides and a trace of trinucleotides are also produced. Each of these products is formed at a constant rate throughout the course of the reaction. The nuclease degrades a DNA chain from the 5'-end. The enzyme preparation contains no detectable endonuclease activity.

Carbon Isotopes↗
PubMed1970

The use of a token system in project Head Start.

The present experiment sought to develop a practical and effective method for teaching the beginning elements of hand-writing in a Head Start program. The method consisted of reinforcing responses to a writing program by giving the children access to a variety of activities normally available in the pre-school classroom. Tokens were presented for correct responses. The children then used the tokens to select reinforcers, such as snacks and access to a variety of play activities. In an experimental evaluation of the token system, it was found that responding was maintained as long as access to the reinforcing activities was contingent upon responding. When reinforcement was no longer contingent upon responding, virtually no responding occurred. Informal observations suggested that the token system had several unanticipated effects: the children's vocabulary and ability to understand instructions improved; a favorable attitude toward school developed; and their ability to play cooperatively with other children increased. It was concluded that the token system is a practical and effective method for teaching beginning writing skills and that it has other desirable, if unanticipated, effects.

Journal Article↗