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Biomedical subjects

M Donahue

Publications and source records attributed to M Donahue.

13 recordsLinked to original sources
PubMed2000

Evidence for X-Ray Emission from a Large-Scale Filament of Galaxies?

Cosmological simulations predict that a large fraction of the baryonic mass of the universe exists as 105-107 K diffuse, X-ray-emitting gas, tracing low-density filament and sheetlike structures exterior to massive clusters of galaxies. If present, this gas helps reconcile the current shortfall in observed baryon counts relative to the predictions of the standard big bang model. We present here the discovery and analysis of a 5 sigma significance half-degree filamentary structure, which is present in both the I-band galaxy surface density and the unresolved X-ray emission in a deep ROSAT PSPC field. The estimated diffuse X-ray emission component of this structure has a surface brightness of approximately 1.6x10-16 ergs s-1 cm-2 arcmin-2 (0.5-2 keV), comparable to the predictions for intercluster gas, and may represent a direct detection of this currently unconfirmed baryonic component.

Journal Article↗
PubMed1995

Brief report: four years after a preterm birth: children's development and their mothers' beliefs and expectations.

Examined the development of preterm-born 4 1/2-year-olds who lived in environments free from socioeconomic disadvantages often associated with deleterious outcomes. Beliefs and expectations of their mothers were also assessed. Thirty-two preterm and 41 comparison children and their mothers participated. Results indicated that although the preterm children were performing at or above age norms on most measures, they scored lower than comparison children in receptive vocabulary, syntactic complexity, articulation, and visual-motor skill. In addition, preterm and comparison group mothers differed in some beliefs and expectations. Results suggest that a preterm birth remains a factor in development during the preschool period, even in a social environment most likely to provide compensatory mechanisms for preterm birth.

Analysis of Variance↗
PubMed1992

The impact of converting to a biphasic blood-culture system on the overall cost and the incidence of pseudobacteremia.

After converting from a conventional broth (CB) system to a biphasic (BP) agar-slide blood-culture system (Septi-Chek), our laboratory noted an increase in positive blood cultures in general, and in coagulase-negative staphylococci (CNS) in particular. To investigate these findings, we compared all blood cultures collected over a 21-month period using CB and then BP systems, totaling 28,199 blood cultures. The frequency of positive blood cultures increased from 9.2% to 12.7% (p less than 0.0001), whereas CNS isolation increased from 2.6% to 5.2% (p less than 0.0001). There was no significant change in the incidence of true primary or secondary bacteremia due to CNS (p = 0.9). The isolation of other pathogens, including Staphylococcus aureus, Candida albicans, Bacteroides species, and Gram-negative bacilli increased from 6.5% to 7.1% (p less than 0.05). We estimated the cost of processing 28,000 blood cultures by both CB and BP systems, using positivity rates of 9.2% and 12.7%, respectively, and standards provided by the College of American Pathologists (CAP, 1991) for workload hours of technologist time. We calculated a higher overall cost for the BP system. However, the use of this system eliminated the use of needles and syringes for subculture of bottles showing no growth, thus decreasing the risk of technologist exposure to body fluids. Despite the increased cost and more frequent occurrence of pseudobacteremia, the enhanced sensitivity and increased safety of the BP system justified its use in the prompt identification of patients with true bacteremia.

Bacteremia↗
PubMed1984

Conversational interactions between mothers and learning-disabled or nondisabled children during a problem-solving task.

This study focused on mother-child interactions during a problem-solving task to determine whether (a) mothers of learning-disabled children engage in conversational buffering to facilitate their child's participation in the task, and (b) whether learning-disabled children differ from nondisabled children in their use of language with their mothers. The results of this study provide some evidence that mothers of both learning-disabled and nondisabled children engage in conversational buffering, although there were few differences between the mothers of the learning-disabled and nondisabled children. Differences between learning-disabled and nondisabled children showed that the learning-disabled were more likely to agree with and less likely to disagree with their mothers than were the nondisabled children. These findings provide some evidence of maternal conversational buffering and suggest that learning-disabled children's previously reported unassertive conversational style in peer interactions extends to talk with their mothers.

Child↗
PubMed1982

Learning disabled children's syntactic proficiency on a communicative task.

Previous studies have generally examined learning disabled children's syntactic ability either on structured tasks or by analyzing oral language samples collected under conditions not typical of natural communicative settings. Thus, these studies are of limited value in exploring the impact of learning disabled children's deficits in linguistic structure on their use of language in social contexts. The purpose of this study was to investigate learning disabled children's syntactic proficiency during a task requiring them to convey information to a listener. Subjects were selected on the bases of teacher ratings, reading achievement scores, and Peabody Picture Vocabulary Test IQ scores within the normal range; those children identified as learning disabled received low ratings and demonstrated underachievement (below 40th percentile for their grade) in reading. Oral language samples were collected by having learning disabled and normally achieving children in grades two, four, six, and eight participate in a referential communication task in which they described abstract shapes to an experimenter. The length and syntactic complexity of the children's descriptions were assessed. Learning disabled children in all grades were found to produce shorter mean t-units and shorter mean main clauses than nondisabled children even on this relatively simple communicative task. Although learning disabled children's linguistic problems have previously been characterized as subtle, these findings suggest that their productive language deficits may be significant enough to interfere with even the informal and elliptical conversations characteristic of communication among peers and family members.

Adolescent↗
PubMed1980

Sex differences in social responsiveness between six months and twelve months.

14 male and 14 female infants were observed interacting with their mothers for 4 min in a free-play situation at 6, 9, and 12 months, using a cross-sectional design. Both mother and infant initiations of interaction and responses to the other's initiations were recorded using an observational technique similar to that used by Clarke-Stewart. There were no age or sex differences in either maternal responsiveness or the number of attempts the mothers made to initiate interaction with the infants. Although no sex difference in responsiveness was observed when the mother used toys to elicit the infant's attention, girls were significantly more responsive when the mother merely spoke to them (vocal initiations). The frequency of social initiations made by the infants increased significantly from 6 to 9 months, but at all 3 ages girls initiated more interactions than did boys. These sex differences in sociability did not reflect differences in the amount of time spent manipulating toys, nor did they reflect sex differences in the frequency of vocalizations, although between 6 and 9 months there was a significant increase for both sexes in the percentage of vocalizations which were used to initiate interactions.

Female↗