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C W Turner

Publications and source records attributed to C W Turner.

At least 73 records · Page 4Linked to original sources
PubMed1991

Health science information management. An approach to improving QA and clinical practice.

To help quality assurance (QA) professionals and clinical practitioners keep up with advances in health care knowledge and technology, we describe a prototype Health Science Information Management (HSIM) publication. We conceptualize HSIM to include: (a) identification of unique science information needs; (b) rapid retrieval of valid needed information; and (c) use the information to improve health care benefits. To more adequately accomplish these functions, we suggest that five specific categories of information will be essential: (1) reports of recent advances in Science Information Management methods; (2) original reports of Science Information Syntheses (SISs) providing information immediately applicable for QA; (3) previously published reports of "classic" SISs relevant to QA; (4) reviews of new technologies and products immediately applicable to quality management; (5) cumulative indexing of the above methods and products. Making the above information available to QA professionals might substantially improve the impact of quality management.

Abstracting and Indexing↗
PubMed1991

Exploring a new best information algorithm for Iliad.

Iliad is a diagnostic expert system for internal medicine. One important feature that Iliad offers is the ability to analyze a particular patient case and to determine the most cost-effective method for pursuing the work-up. Iliad's current "best information" algorithm has not been previously validated and compared to other potential algorithms. Therefore, this paper presents a comparison of four new algorithms to the current algorithm. The basis for this comparison was eighteen "vignette" cases derived from real patient cases from the University of Utah Medical Center. The results indicated that the current algorithm can be significantly improved. More promising algorithms are suggested for future investigation.

Algorithms↗
PubMed1991

Iliad training effects: a cognitive model and empirical findings.

Iliad is a diagnostic expert system consisting of an "inference engine" (collection of rules and procedures for making decisions) and a "knowledge base" (collection of medical facts). Iliad's internal medicine knowledge base recognizes 5000 medical findings and covers 1150 diagnostic conditions in 10 subspecialty fields. We used Iliad's simulator mode to train diagnostic skills in junior-year medical students. The results corroborate previous findings documenting Iliad's teaching efficacy. Recent developments in cognitive psychology provide a framework for explaining Iliad's training effects.

Clinical Clerkship↗
PubMed1990

Type of hemodialysis and preference for behavioral involvement: interactive effects on adherence in end-stage renal disease.

Examined the effects of hemodialysis type (i.e., staff controlled, in center vs. patient controlled, home) and patient preference for behavioral involvement on adherence and emotional adjustment in a sample of 53 patients with end-stage renal disease. Consistent with person x treatment interaction models, higher levels of preference for behavioral involvement were associated with better dietary adherence (i.e., lower serum potassium) for patients receiving dialysis at home but worse dietary adherence for patients receiving treatment in a dialysis center. A similar though weaker patient x treatment type matching pattern was observed for fluid-intake adherence (i.e., interdialytic weight gain). No effects were observed for patients' self-reported depression levels. Possible mechanisms for the interactional effect on adherence are discussed.

Adult↗
PubMed1990

Recognition of voiceless fricatives by normal and hearing-impaired subjects.

The purpose of this study was to investigate the sufficient perceptual cues used in the recognition of four voiceless fricative consonants [s, f, theta, integral of] followed by the same vowel [i:] in normal-hearing and hearing-impaired adult listeners. Subjects identified the four CV speech tokens in a closed-set response task across a range of presentation levels. Fricative syllables were either produced by a human speaker in the natural stimulus set, or generated by a computer program in the synthetic stimulus set. By comparing conditions in which the subjects were presented with equivalent degrees of audibility for individual fricatives, it was possible to isolate the factor of lack of audibility from that of loss of suprathreshold discriminability. Results indicate that (a) the friction burst portion may serve as a sufficient cue for correct recognition of voiceless fricatives by normal-hearing subjects, whereas the more intense CV transition portion, though it may not be necessary, can also assist these subjects to distinguish place information, particularly at low presentation levels; (b) hearing-impaired subjects achieved close-to-normal recognition performance when given equivalent degrees of audibility of the frication cue, but they obtained poorer-than-normal performance if only given equivalent degrees of audibility of the transition cue; (c) the difficulty that hearing-impaired subjects have in perceiving fricatives under normal circumstances may be due to two factors: the lack of audibility of the frication cue and the loss of discriminability of the transition cue.

Adult↗
PubMed1990

Pure-tone increment detection in harmonic and inharmonic backgrounds.

The present study investigated the effect of increasing the number and frequency range of background components upon the detection of an increment to the intensity of the center component. Previous studies [e.g., Green et al., J. Acoust. Soc. Am. 75, 1163-1167 (1984)] have demonstrated that, for background stimuli consisting of logarithmically spaced pure-tone components, as the number of background components is increased, the threshold for detection of an increment to the center component is decreased. The present study investigated this effect using harmonically spaced, as well as logarithmically spaced, backgrounds, because many natural sounds, including voiced speech sounds, consist of harmonically spaced components. Two conditions were employed for both types of backgrounds, fixed-level and roving-level within a trial. Group results revealed a small decrease in threshold with increasing number of components only for the fixed-level, logarithmically spaced backgrounds. No decrease in threshold was observed for the other three conditions, including the roving-level, logarithmically spaced backgrounds which were the same as those used by Green et al. (1984). The present results suggest that the decrease in signal threshold with increasing number of background components exists only under limited conditions and that it is a highly individual phenomenon. The present results also suggest that the effect does not occur for harmonically spaced complexes such as most natural sounds including voiced speech.

Attention↗
PubMed1990

Summation bandwidths at threshold in normal and hearing-impaired listeners.

The bandwidths for summation at threshold were measured for subjects with normal hearing and subjects with sensorineural hearing loss. Thresholds in quiet and in the presence of a masking noise were measured for complex stimuli consisting of 1 to 40 pure-tone components spaced 20 Hz apart. The single component condition consisted of a single pure tone at 1100 Hz; additional components were added below this frequency, in a replication of the Gässler [Acustica 4, 408-414 (1954)] procedure. For the normal subjects, thresholds increased approximately 3 dB per doubling of bandwidth for signal bandwidths exceeding the critical bandwidth. This slope was less for the hearing-impaired subjects. Summation bandwidths, as estimated from two-line fits, were wider for the hearing-impaired than for the normal subjects. These findings provide evidence that hearing-impaired subjects integrate sound energy over a wider-than-normal frequency range for the detection of complex signals. A second experiment used stimuli similar to those of Spiegel [J. Acoust. Soc. Am. 66, 1356-1363 (1979)], and added components both above and below the frequency of the initial component. Using these stimuli, the slope of the threshold increase beyond the critical bandwidth was approximately 1.5 dB per doubling of bandwidth, thus replicating the Spiegel (1979) experiment. It is concluded that the differences between the Gässler (1954) and Spiegel (1979) studies were due to the different frequency content of the stimuli used in each study. Based upon the present results, it would appear that the slope of threshold increase is dependent upon the direction of signal expansion, and the size of the critical bands into which the signal is expanded.

Adult↗
PubMed1989

Perceived family support as a moderator psychological well-being in end-stage renal disease.

End-stage renal disease (ESRD) is associated with an increased incidence of psychological distress. The present research examined the salutary effects of a supportive family environment on the psychological well-being of ESRD patients receiving renal transplants. Patients (N = 57) completed a measure of perceived family support and an assessment of the physical impact of their illness. Psychological well-being was assessed utilizing two measures of depression and two measures of anxiety. One group of patients was classified as experiencing high illness-related physical dysfunction. In this group, patients perceiving a less supportive family environment displayed significantly higher levels of psychological symptoms of depression and anxiety than patients with a more supportive family environment. A second group of patients was classified as experiencing low illness-related physical dysfunction. In this group, the perceived level of family support was not significantly related to their relatively lower reported levels of depression and anxiety.

Adaptation, Psychological↗
PubMed1989

The relation between vowel recognition and measures of frequency resolution.

The purpose of this study was to employ measures of frequency resolution obtained from individual subjects to predict each subject's vowel recognition performance. Input filter patterns at six test frequencies were obtained from normal-hearing and hearing-impaired subjects. These patterns were used to correlate frequency resolution with vowel recognition in those same subjects. Vowels were presented at levels at which the entire spectrum was fully audible to each subject. Using each subject's measured filter characteristics (and interpolated values for intermediate frequencies), an "internal spectrum" of each vowel was calculated by determining the outputs of all filter channels for the vowel as the input signal. It was speculated that the more similar two internal spectra for a subject were, the more often they would be confused in the vowel recognition task. This expectation received some support when the measure of similarity was a point-by-point Euclidean distance between the two internal spectra. Stronger support was obtained when the measure of similarity was based upon Klatt's (1982) "weighted slope metric" that emphasizes similarities of spectral peak locations. The present study demonstrates a relation between impairments of frequency resolution and vowel recognition. The described filter-bank model of vowel recognition suggests that measures of frequency resolution along with the acoustic spectra of vowel stimuli may be useful in predicting the recognition of vowels by individuals.

Adult↗
PubMed1989

Forward-masking properties of multicomponent signals in normal and hearing-impaired subjects.

The forward-masking properties of inharmonic complex stimuli were measured both for normal and hearing-impaired subjects. The signal threshold for a 1000-Hz pure-tone probe was obtained for six different maskers, which varied in the number of pure-tone components. The masking stimuli consisted of 1, 3, 5, 7, 9, or 11 components, logarithmically spaced in frequency surrounding the signal and presented at a fixed level of 80 dB SPL per component. In most normal-hearing subjects, the threshold for the probe decreased as the number of masking components was increased, demonstrating that stimuli with more components tended to be less effective maskers. Results from hearing-impaired subjects showed no decrease in threshold with increasing number of masking components. Instead, the thresholds increased as more components were added to the first masker. These results appear to be consistent with suppression effects within the multicomponent maskers for the normal subjects and a lack of suppression effects for the hearing-impaired subjects. The results from the normal-hearing subjects are also consistent with "across-channel" cuing.

Adult↗
PubMed1989

Intensity discrimination determined with two paradigms in normal and hearing-impaired subjects.

The literature on auditory intensity jnd's is ambiguous with respect to the relationship between the jnd's measured with gated and continuous pedestals and with respect to changes in this relationship in the presence of loudness recruitment accompanying cochlear pathology. In an attempt to clarify these issues and to lay a foundation for systematic investigations of the dependence on the jnd's on loudness functions, the jnd's for pure tones with gated- and continuous-pedestal paradigms of two groups of subjects, one with normal hearing and one with hearing loss of cochlear origin, were measured. The experiments were performed at 0.5, 2, and 6 kHz, and at a wide range of sensation levels (SLs) by means of an adaptive two-alternative, forced-choice (2IFC) procedure. The jnd's obtained with the continuous-pedestal method were smaller than those obtained with the gated-pedestal method for both groups of subjects. They also had smaller intersubject standard deviations. When jnd's of the two groups were compared on the basis of equal SLs, the group with hearing loss showed smaller jnd values than the group with normal hearing for both pedestal paradigms. When the comparisons were made on the basis of equal sound-pressure levels (SPLs), both groups showed similar values for moderate and high SPLs. At relatively low SPLs, the group with hearing loss tended to have somewhat higher values.

Acoustic Stimulation↗
PubMed1989

Utility of the MMPI in a geriatric population.

Despite the popularity of the Minnesota Multiphasic Personality Inventory (MMPI), there exists a relative dearth of normative and validity research regarding its use with persons over the age of 60. Our investigation was designed to examine the MMPI performance of both a normal and a clinical sample of older men and women. Specifically, a nonpatient community sample of 204 subjects and an outpatient psychiatric sample of 30 subjects, between the ages of 60 and 90, were administered the MMPI as well as structured psychiatric interview, the Psychiatric Status Schedule (PSS). Results revealed that, on most of the MMPI scales, the mean scores were well above the norms (i.e., 5-10 t-score points). Through comparisons between the clinical and community subjects as well as between MMPI and PSS performance, the MMPI demonstrated substantial discriminative and concurrent criterion validity within this geriatric sample. The results of the study suggest that, with a few important exceptions, the MMPI, as generally utilized, is valid for use in the geriatric population.

Aged↗
PubMed1988

Disease based spectrum bias in referred samples and the relationship between type A behavior and coronary artery disease.

Using referred samples to study predictors of disease produces statistical problems that reduce the likelihood of obtaining statistically significant results even when a substantial relationship is present between a risk factor and a disease. The present paper refers to these problems as disease based spectrum (DBS) bias. DBS bias is present when subjects are directed into or excluded from the study sample according to their disease status. For example, healthy individuals are excluded from and diseased individuals are directed into referred samples. Therefore, DBS bias is present in referred samples. Examples from the literature on Type A behavior and coronary artery disease (CAD) are presented to illustrate how DBS bias reduces statistical associations. The results of the current research indicate DBS bias has reduced the association between Type A behavior and CAD in a number of studies reported in recent years. In addition, the present article discusses techniques for assessing and controlling for DBS bias.

Age Factors↗
PubMed1988

A reexamination of forward masking in the auditory nerve.

Forward masking, as measured behaviorally, is defined as an increase in a signal's detection threshold resulting from a preceding masker. Previously, forward masking in the auditory nerve has been measured as a reduction in the neural response to a signal when preceded by a masker. However, detection threshold depends on both the magnitude of the response to the signal and the variance of the response. Thus changes in detectability cannot be inferred from response reduction alone. Relkin and Pelli (1987) have described a two-interval forced-choice procedure that may be used to measure the threshold for the detection of a probe signal in recordings of spike counts in single auditory neurons. These methods have been used to study the forward masking of characteristic frequency probe tones by characteristic frequency maskers as masker intensity was varied. Although the masker does reduce the detectability of the probe tone, it was found that the threshold shifts are much less than those observed behaviorally, particularly for intense maskers. In part, the small threshold shifts can be attributed to the reduction in response variance following the masker, which is the result of the adaptation of spontaneous activity. These results imply that behavioral forward masking must result from suboptimal processing of spike counts from auditory neurons at a location central to the auditory nerve.

Animals↗
PubMed1987

Blood pressure reactivity in adult male twins.

The purpose of the present investigation was to examine possible genetic contributions to cardiovascular reactivity by contrasting patterns of association in 82 monozygotic (MZ) and 88 dizygotic (DZ) adult male twin pairs (age range = 21 to 61 years, M = 35 years). Systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) were recorded during baseline and during a mental arithmetic task (i.e., serial subtraction). The task produced significant elevations in all three cardiovascular measures (i.e., 10 mmHg SBP, 8 mmHg DBP, and 6 bpm HR, respectively). Levels of SBP and DBP reactivity were significantly correlated in MZ pairs but not in DZ pairs. Statistical tests suggest a heritability estimate of about 50% that was marginally significantly for SBP and DBP changes during the task. There was no indication of a genetic influence on HR reactivity. Resting level and static task period measures of SBP, DBP, and HR demonstrated statistically significant heritability estimates of 60% to 80%.

Adult↗
PubMed1987

Audibility and recognition of stop consonants in normal and hearing-impaired subjects.

The purpose of this study was to examine the effect of spectral-cue audibility on the recognition of stop consonants in normal-hearing and hearing-impaired adults. Subjects identified six synthetic CV speech tokens in a closed-set response task. Each syllable differed only in the initial 40-ms consonant portion of the stimulus. In order to relate performance to spectral-cue audibility, the initial 40 ms of each CV were analyzed via FFT and the resulting spectral array was passed through a sliding-filter model of the human auditory system to account for logarithmic representation of frequency and the summation of stimulus energy within critical bands. This allowed the spectral data to be displayed in comparison to a subject's sensitivity thresholds. For normal-hearing subjects, an orderly function relating the percentage of audible stimulus to recognition performance was found, with perfect discrimination performance occurring when the bulk of the stimulus spectrum was presented at suprathreshold levels. For the hearing-impaired subjects, however, it was found in many instances that suprathreshold presentation of stop-consonant spectral cues did not yield recognition equivalent to that found for the normal-hearing subjects. These results demonstrate that while the audibility of individual stop consonants is an important factor influencing recognition performance in hearing-impaired subjects, it is not always sufficient to explain the effects of sensorineural hearing loss.

Adult↗
PubMed1987

Discrimination of spectral-peak amplitude by normal and hearing-impaired subjects.

The present study compared the abilities of normal and hearing-impaired subjects to discriminate differences in the spectral shapes of speechlike sounds. The minimum detectable change in amplitude of a second-formant spectral peak was determined for steady-state stimuli across a range of presentation levels. In many cases, the hearing-impaired subjects required larger spectral peaks than did the normal-hearing subjects. The performance of all subjects showed a dependence upon presentation level. For some hearing-impaired subjects, high presentation levels resulted in discrimination values similar to that of normal-hearing subjects, while for other hearing-loss subjects, increases in presentation level did not yield normal values, even when the second-formant spectral region was presented at levels above the subject's sensitivity thresholds. These results demonstrate that under certain conditions, some sensorineural hearing-impaired subjects require more prominent spectral peaks in certain speech sounds than normal subjects for equivalent performance. For the group of subjects who did not achieve normal discrimination results at any presentation level, application of high-frequency amplification to the stimuli was successful in returning those subjects' performance to within normal values.

Adult↗