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Biomedical subjects

C N Johnson

Publications and source records attributed to C N Johnson.

28 records · Page 2Linked to original sources
PubMed1997

Relatedness structure detected by microsatellite analysis and attempted pedigree reconstruction in an endangered marsupial, the northern hairy-nosed wombat Lasiorhinus krefftii.

The northern hairy-nosed (NHN) wombat is perhaps Australia's most endangered mammal. Being fossorial and nocturnal as well as rare, NHN wombats are difficult to observe in the wild. Hence little is known of their social biology, such as their mating and dispersal systems. A hypothesis has been advanced that adult females of the species disperse post-breeding, leaving their young to inhabit the natal burrow. Female-biased dispersal is expected to result in higher relatedness amongst males in a burrow cluster than amongst females in a burrow cluster. The usefulness of a panel of microsatellite markers in estimating the relatedness structure, and in reconstructing pedigrees for, the sole known population of NHN wombats was assessed. Microsatellite genotypes at eight or nine loci were obtained from 58 of the 85 known individuals, and used to estimate pairwise individual relatedness using Queller & Goodnight's (1989) RELATEDNESS 4.2. Our analysis gave the unexpected result that both males and females were significantly more closely related to their same-sex burrow cluster mates than random, while opposite-sex animals sharing burrows were only slightly (nonsignificantly) more related than random. This raises the possibility of dispersal patterns which lead to association of same-sex relatives. The observed relatedness structure is not expected to make likely a high incidence of inbred matings, as close relatives of the opposite sex are not significantly associated in space. Parentage analysis was attempted using genetic exclusion and LOD likelihood ratios, but proved difficult because of low genetic variation, incomplete sampling of potential parents, and paucity of ecological data such as known mother/offspring pairs and ages of individuals.

Animals↗
PubMed1997

Crazy children, fantastical theories, and the many uses of metaphysics.

Woolley rightly challenges the incredible idea, held by some adults, that it is children who are peculiarly "fantastical" in their thinking. However, Woolley expresses little appreciation for "fantastical thinking" as it underlies the capacity for both grand delusions and amazing insights. In reducing "fantastical thinking" to conceptual error, she overlooks the mythical underpinnings of her own theorizing and neglects the many constructive roles of "fantastical thinking" in development.

Adult↗
PubMed1996

Orthodontia.

Explore the source record for details and available documents.

Child↗
PubMed1990

Synthesis and evaluation of a series of aryl[e]fused pyrazolo[4,3-c]pyridines with potential anxiolytic activity.

A series of pyrazolo[4,3-c]pyridines has been synthesized and evaluated as potential anxiolytic agents. Selected compounds from this series show a pharmacological profile of action different from that of diazepam. A number of the compounds possess higher affinity for central benzodiazepine receptors than diazepam, yet show less anticonvulsant activity and are less sedative. The structure-activity relationships of these potential anxiolytic agents are discussed.

Animals↗
PubMed1990

If you had my brain, where would I be? Children's understanding of the brain and identity.

When do children distinguish a person's subjective identity from their outward bodily characteristics? As adults this distinction is evident in our commonsense recognition that a hypothetical brain transplant would entail a transplant of the mind or self. 4 studies were conducted to examine children's judgments about hypothetical body part transplants, including transplants of the brain, heart, mouth, and face. The results showed that during the elementary school years children are acquiring a firm understanding of the brain as the primary locus of psychological attributes and identity. The early school years, between the ages of 5 and 7 years, appeared to be a transitional phase, with performance being variable and subject to task conditions. While children this age readily imagined the consequences of transplants between themselves and another character of categorically different status (i.e., a pig or baby), they had great difficulty with proposed transplants between themselves and another child of the same status. Knowledge about categorical differences appeared to provide a needed framework for children's budding thinking about psychological differences.

Body Image↗
PubMed1988

Dispersal and the sex ratio at birth in primates.

The females of many species of primates settle for life within the home ranges of their mothers, whereas males disperse as immatures. According to the theory of sex allocation, the costs incurred by mothers through local competition for resources with their philopatric daughters should favour the evolution of male-biased sex ratios at birth. I report here two tests of this hypothesis based on data from 15 genera of primates. First, I show that the intensity of competition for resources within kin groups is strongly and positively correlated with sex ratios at birth. Second, I show that sex ratios at birth are higher in genera with female-biased philopatry than in genera in which philopatry is not female-biased. These analyses suggest that local resource competition among kin powerfully influences the evolution of sex ratios in primates.

Animals↗
PubMed1982

Children's developing conceptions of the mind and brain.

Previous investigators have examined children's knowledge about particular cognitive performances such as metamemory, or particular mental acts, such as dreams. The present research adds a new dimension by considering children's concepts of the mind as a whole. The development of concepts of both the mind and brain is examined in subjects from preschool age through adulthood. Evidence is presented to show that by ages 4 and 5 years children commonly regard the brain as an internal mindlike entity associated with a class of distinctly mental acts. This runs counter to previous characterizations of young children as failing to distinguish mental from overt behavioral acts. Young children begin with undifferentiated conceptions of the mind and brain. Both entities are regarded as necessary for mental, but not sensory-motor actions. In subsequent developments, the concepts of the mind and brain are differentiated along 2 lines. Ontologically, the mind is distinguished by its immateriality; functionally, the brain is distinguished by its involvement in bodily actions. The development of knowledge about the brain is discussed with respect to acquiring "popular" and "technical" definitions. The results are regarded as contributing toward understanding how children come to organize information about the mental world as a whole.

Adult↗
PubMedDate not supplied

An experimental test of affect, subjective craving, and alcohol outcome expectancies as motivators of young adult drinking.

Research on motivations for alcohol use suggests that both positive and negative affect, craving, and outcome expectancies are good predictors of alcohol consumption. The present study tested the utility of these variables in predicting laboratory measures of alcohol consumption among young social drinkers. Two conditioning models of alcohol procurement guided analyses: the conditioned withdrawal model (represented by negative affect and craving) and the appetitive-motivational model (represented by positive outcome expectancies and subjective evaluations). Results showed that negative affect and craving did not significantly influence either subjects' latencies to begin drinking or speed of consuming one placebo beverage. Positive outcome expectancies and evaluations, however, had a marked impact on speed of drinking. Thus, the appetitive-motivational model appears to better characterize the drinking patterns of young social drinkers than does the conditioned withdrawal model.

Adult↗