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Biomedical subjects

S H Brown

Publications and source records attributed to S H Brown.

62 records · Page 4Linked to original sources
PubMedDate not supplied

Control of simple arm movements in elderly humans.

Eight elderly subjects (aged 68-95 years) and 6 young adults (aged 21-24 years) performed elbow flexion and extension movements in a visual step-tracking paradigm. Movement amplitudes ranging from 10 degrees-80 degrees were made under two instructions: "move at own speed" and "move fast and accurate." In a second experiment, 5 elderly subjects practiced 30 degrees movements for a total of 180 flexion and 180 extension movements under the instruction to increase movement speed, while maintaining accuracy, during practice. Movement trajectories became more variable as both movement amplitude and speed increased. Trajectory variability was greater in the elderly subjects for both the acceleratory and deceleratory phases of movements. This was due primarily to a greater rate of increase in trajectory variability during the acceleration phase in the elderly. With practice, elderly subjects could substantially reduce trajectory variability with little change in movement speed. The agonist burst initiating movements was qualitatively normal in the elderly subjects. However, there was considerable tonic cocontraction of agonist and antagonist muscles prior to and during movement. Phasic antagonist EMG activity was obviously abnormal in many elderly subjects. There was often no clear antagonist burst associated with deceleration of the movements or, if present, it was timed inappropriately early. With practice, combined agonist-antagonist EMG variability decreased. A clear antagonist burst also developed during practice in most elderly subjects, but its inappropriate timing remained in all but one subject. The results show that movement trajectories are less accurately controlled in the elderly.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Kinematics of arm movements in elderly humans.

Changes in the kinematics of arm movements with age were studied. "Young" (aged 21-23) and "elderly" (aged 68-95) subjects performed a visually guided, step tracking task. Each subject performed movements of eight different amplitudes (10-80 deg) at two volitionally determined speeds ("own speed," "fast and accurate"). Movement durations and maximum velocities were similar for both groups and increased with movement amplitude under all conditions. The young subjects made movements in which approximately the same length of time was spent in accelerating as in decelerating the movement. In contrast, movements by the elderly subjects were temporally asymmetrical, the deceleration phase being longer than the acceleration phase. The ratio of maximum to average velocities (Vm/Vav) was markedly different between the young and elderly subjects, particularly in the smaller amplitude movements (less than 40 deg). Values of this parameter ranged from 1.5 to 6 in the elderly subjects. Movements made by the elderly subjects were more variable than those of the young subjects, particularly so at smaller amplitudes. Variability was most apparent in the deceleratory phase of movement where the elderly subjects often showed hypermetria. Some elderly subjects also showed movement decomposition, the movements being made as a series of discrete submovements. Thus, the elderly subjects displayed some of the characteristics classically described as arising from cerebellar dysfunction.

Adult↗
PubMedDate not supplied

Automated enhancement of description logic-defined terminologies to facilitate mapping to ICD9-CM.

Compositional (post-coordinated) terminologies are one potential solution to the problem of content completeness. However, they have the potential to render data incomparable. For computers to determine that compositional expressions are comparable, the relations between the composed components that are understood implicitly by human readers must be represented explicitly for computer manipulation. We discuss a technique for discovering and formalizing the implicit semantic relationships in two vocabularies: the International Classification of Disease Version 9 Clinical Modification (ICD9-CM), and SNOMED-Reference Terminology (SNOMED-RT). The results of this technique are used to augment the existing SNOMED-RT relation ontology, which is a necessary step in automated concept mapping between systems. The reference terminology must contain all the semantics implicit in the classification in order to map concepts between the two representations. We also provide an explicit representation of the implied semantics of ICD9-CM. This tabulation will be useful for other knowledge engineering efforts involving ICD9-CM.

Automation↗
PubMedDate not supplied

Changes in physicians' computer anxiety and attitudes related to clinical information system use.

UNLABELLED: STUDY OVERVIEW: Interns' anxiety about computer use ("computer anxiety") and their attitudes toward medical computer applications were determined by a standardized questionnaire. Participants were surveyed before and after three months of differential exposure to three clinical information systems (CISs), including one with provider-entered encounters. POPULATION: Fifty-one interns completed both surveys. Their average age was 27 years. Thirty-three percent were female, 7% were African American, and 8% were foreign graduates. RESULTS: The most common previous exposures to computers were for literature searching and retrieval of patient information (both 92%). Factors that commonly emerged as predictive of anxiety about computer use included self-rated skills, typing ability, and computer attitudes. Factors predictive of attitudes toward computers included self-rated skills, typing ability, maximal frequency of prior computer use, computer ownership, and computer anxiety. Factors that were not predictive of computer anxiety or attitudes toward computers included age, gender, and physician input of data. CONCLUSION: Identification of markers for negative psychological reactions to computer use may allow development of interventions to improve acceptance of computer base patient records (CBPRs).

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PubMedDate not supplied

Derivation and evaluation of a document-naming nomenclature.

OBJECTIVE: The Computerized Patient Record System is deployed at all 173 Veterans Affairs (VA) medical centers. Providers access clinical notes in the system from a note title menu. Following its implementation at the Nashville VA Medical Center, users expressed dissatisfaction with the time required find notes among hundreds of irregularly structured titles. The authors' objective was to develop a document-naming nomenclature (DNN) that creates informative, structured note titles that improve information access. DESIGN: One thousand ninety-four unique note titles from two VA medical centers were reviewed. A note-naming nomenclature and compositional syntax were derived. Compositional order was determined by user preference survey. MEASUREMENTS: The DNN was evaluated by modeling note titles from the Salt Lake City VA Medical Center (n=877), Vanderbilt University Medical Center (n=554), and the Mayo Clinic (n=42). A preliminary usability evaluation was conducted on a structured title display and sorting application. RESULTS: Classes of note title components were found by inspection. Components describe characteristics of the author, the health care event, and the organizational unit providing care. Terms were taken from VA medical center information systems and national standards. The DNN model accurately described 97 to 99 percent of note titles from the test sites. The DNN term coverage varied, depending on component and site. Users found the DNN title format useful and the DNN-based title sorting and note review application easy to learn and quick to use. CONCLUSION: The DNN accurately models note titles at five medical centers. Preliminary usability data indicate that DNN integration with title parsing and sorting software enhances information access.

Abstracting and Indexing↗