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Biomedical subjects

D B Marshall

Publications and source records attributed to D B Marshall.

7 recordsLinked to original sources
PubMed2001

The effect of fathers or father figures on child behavioral problems in families referred to child protective services.

This study examines some possible effects of the presence and quality of parent-child interaction of fathers and father figures on the behavior of young children in a sample of families reported to child protective services. Whereas the presence or absence of a father or father figure seemed to make little difference in child behavioral problems at age 4, lower levels of aggression and depression were observed for children by age 6 if an adult male in some form of father-like relationship was present in the child's life. When controlling for mother's ethnicity, child's gender, the number of referrals to child protective services, and the presence of domestic violence, the direct effect of a father/father figure was no longer significant but remained in the multivariate models as a significant interaction term.

Adult↗
PubMed2000

Neural network modeling of risk assessment in child protective services.

The advantages of using neural network methodology for the modeling of complex social science data are demonstrated, and neural network analysis is applied to Washington State Child Protective Services risk assessment data. Neural network modeling of the association between social worker overall assessment of risk and the 37 separate risk factors from the State of Washington Risk Assessment Matrix is shown to provide case classification results superior to linear or logistic multiple regression. The improvement in case prediction and classification accuracy is attributed to the superiority of neural networks for modeling nonlinear relationships between interacting variables; in this respect the mathematical framework of neural networks is a better approximation to the actual process of human decision making than linear, main effects regression. The implications of this modeling advantage for evaluating social science data within the framework of ecological theories are discussed.

Child↗
PubMed1999

Assessment of Amblyseius fallacis (Acari: Phytoseiidae) for biological control of tetranychid mites in an Ontario peach orchard.

We introduced a mass-reared pyrethroid-resistant strain of the predatory phytoseiid mite Amblyseius fallacis (Garman) into an Ontario peach orchard in an attempt to control populations of the phytophagous mites Panonychus ulmi Koch and Tetranychus urticae Koch (Acari: Tetranychidae). Releases of 1,000 and 2,000 mites per tree were made, at three different times. The release of 2,000 mites per tree in June and in July resulted in significantly higher phytoseiid densities than was observed on control trees. However, densities of P. ulmi or T. urticae were not significantly affected by any release rate or by timing. The release of 1,000 A. fallacis per tree, or of any density in August, did not significantly increase phytoseiid abundance. In the following year, population dynamics of both phytoseiid and phytophagous mites were not significantly affected by the previous year's release. Amblyseius fallacis can be a useful predator in some fruit orchards. However, further research is necessary into the timing and rate of release, modified spray programmes, and with different crops, in order to clarify the role of this species for biological control in Ontario peach orchards.

Aerosols↗
PubMed1996

Mapping leaf surface landscapes.

Leaf surfaces provide the ecologically relevant landscapes to those organisms that encounter or colonize the leaf surface. Leaf surface topography directly affects microhabitat availability for colonizing microbes, microhabitat quality and acceptability for insects, and the efficacy of agricultural spray applications. Prior detailed mechanistic studies that examined particular fungi-plant and pollinator-plant interactions have demonstrated the importance of plant surface topography or roughness in determining the outcome of the interactions. Until now, however, it has not been possible to measure accurately the topography--i.e., the three-dimensional structure--of such leaf surfaces or to record precise changes in patterns of leaf surface elevation over time. Using contact mode atomic force microscopy, we measured three-dimensional coordinates of upper leaf surfaces of Vaccinium macrocarpon (cranberry), a perennial plant, on leaves of two age classes. We then produced topographic maps of these leaf surfaces, which revealed striking differences between age classes of leaves: old leaves have much rougher surfaces than those of young leaves. Atomic force microscope measurements were analyzed by lag (1) autocorrelation estimates of leaf surfaces by age class. We suggest that the changes in topography result from removal of epicuticular lipids and that the changes in leaf surface topography influence phylloplane ecology. Visualizing and mapping leaf surfaces permit detailed investigations into leaf surface-mediated phenomena, improving our understanding of phylloplane interactions.

Journal Article↗
PubMed1975

A survey of the use of on-line computer-based scientific search services by academic libraries.

To explore their use of on-line computer-based bibliographic search services, a one-page questionnaire was sent to 100 academic libraries in the United States having separate departmental chemistry or science libraries. An attempt was made to determine the background training of the persons performing the searches, who the end users were, the growth trend, the funding, the data bases used, and the value to the users. Of the 73 replies, 49.3% indicated use of such services, while 24.6% were planning to use them primarily by faculty and graduate students. Of those reporting, 83.3% used searchers with a background in library or information science; 47.2% had a background in scientific discipline. Two or more on-line services were used by 72.2%. A majority of respondents stated that the user paid all expenses or a portion of the expenses. The searches met the needs of the user most of the time in 83.3% of the cases, and all of the time in 5.4%.

Information Systems↗
PubMedDate not supplied

Equine post-anesthetic lameness. A retrospective study.

The incidence of post-anesthetic lameness in 655 horses undergoing 733 anesthetic episodes over a 3 year period was 6.4%. Nineteen factors previously reported or proposed to play a role in the development of post-anesthetic lameness were evaluated statistically. Only hypotension and the duration of the anesthetic period were significant factors.

Age Factors↗