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B Lindsay

Publications and source records attributed to B Lindsay.

7 recordsLinked to original sources
PubMed1992

Computer-assisted analysis of mixtures (C.A.MAM): statistical algorithms.

This paper presents various algorithmic approaches for computing the maximum likelihood estimator of the mixing distribution of a one-parameter family of densities and provides a unifying computer-oriented concept for the statistical analysis of unobserved heterogeneity (i.e., observations stemming from different subpopulations) in a univariate sample. The case with unknown number of population subgroups as well as the case with known number of population subgroups, with emphasis on the first, is considered in the computer package C.A.MAN (Computer Assisted Mixture Analysis). It includes an algorithmic menu with choices of the EM algorithm, the vertex exchange algorithm, a combination of both, as well as the vertex direction method. To ensure reliable convergence, a step-length menu is provided for the three latter methods, each achieving monotonicity for the direction of choice. C.A.MAN has the option to work with restricted support size-that is, the case when the number of components is known a priori. In the latter case, the EM algorithm is used. Applications of mixture modelling in medical problems are discussed.

Algorithms↗
PubMed1990

Cardiovascular response to isokinetic endurance exercise testing.

The purpose of this study was to compare specific cardiovascular responses; maximal heart rate (MHR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and the calculated pressure rate product (PRP) [SPB X HR X 10(-2)] achieved during a Cybex+ isokinetic endurance test to those generated during a maximal graded exercise test (GXT). Nine untrained college females underwent a Bruce GXT and a maximal effort Cybex knee endurance test. Independent t-tests were used to analyze the differences between the means for MHR, SPB, DBP, and PRP elicited during both tests. There was no significant difference (p less than 0.01) between SBP and DBP means elicited during either test. MHR was significantly higher on the GXT with Cybex values ranging from 71 to 88% of GXT values. PRP was significantly lower during Cybex exercise but ranged from 58 to 102% of maximal GXT values. The results of this study demonstrate the high demands that a Cybex endurance test places on the cardiovascular system of this healthy population and also emphasize the need to carefully evaluate and monitor these parameters for clients of all ages and diagnoses.

Adult↗
PubMed1977

Relation between cell wall turnover and cell growth in Bacillus subtilis.

The kinetics of cell wall turnover in Bacillus subtilis have been examined in detail. After pulse labeling of the peptidoglycan with N-acetylglucosamine, the newly formed peptidoglycan is stable for approximately three-quarters of a generation and is then degraded by a process that follows first-order kinetics. Deprivation of an auxotroph of amino acids required for protein synthesis results in a cessation of turnover. If a period of amino acid starvation occurs during the lag phase of turnover, then the initiation of turnover is delayed for a period of time equivalent to the starvation period. During amino acid starvation, new cell wall peptidoglycan is synthesized and added to preexisting cell wall. This peptidoglycan after resumption of growth is also subject to degradation (turnover). It is suggested that cell wall turnover is dependent on cell growth and elongation. Several possible control mechanisms for cell wall autolytic enzymes are discussed in light of these observations.

Acetylglucosamine↗
PubMed1976

Characterization of the N-acetylmuramic acid L-alanine amidase from Bacillus subtilis.

The N-acetylmuramic acid L-alanine amidase from Bacillus subtilis W-23 has been purified to apparent homogeneity. The enzyme is a monomer of molecular weight 51,000, which binds extremely tightly to homologous cell walls but not to heterologous cell walls, even of the closely related strain B. subtilis ATCC 6051. This difference in binding is only in part due to differences in teichoic acid between these two strains and to a large extent appears to represent differences in the arrangement of the peptidoglycan. A comparison of the amidase from B. subtilis W-23 and the enzyme previously purified from B. subtilis ATCC 6051 (Herbold and Glaser, 1975) shows that the two proteins, which cleave the same bond and are of the same size, do not cross-react immunologically and that the two enzymes are, therefore, not closely related in structure.

Amidohydrolases↗