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At least 19 recordsLinked to original sources
PubMedDate not supplied

Acoustic reflex thresholds using conventional and tracking methods.

Relationship between acoustic reflex thresholds obtained using conventional and tracking procedures was investigated. In the tracking method, the intensity of the stimulus from a self-recording audiometer is adjusted by the experimenter to bracket the acoustic reflex threshold as visually observed on the meter of an acoustic impedance measuring device. Acoustic reflex thresholds were obtained to pure tones of 500, 1000, and 4000 Hz. High correlations and no significant differences were obtained between the two threshold methods. It was concluded that the tracking method which allows easier control of stimulus parameters and response recording can provide acoustic reflex threshold data similar to those obtained using a conventional method.

Audiometry↗
PubMed2025

Comparison of three tracking methods to assess usage of two pediatric powered mobility devices for young children with cerebral palsy.

Powered mobility devices are underutilized for promoting self-initiated mobility in young children with cerebral palsy due to prioritization of walking, caregiver effort, device characteristics, and environmental factors. Understanding device usage patterns is important to assess the impact of powered mobility interventions on child outcomes. As part of clinical trial (NCT04684576), three objective tracking methods including integrated loggers, Global Positioning System trackers (GPST), and caregiver reported activity logs (CRAL) were compared to provide insights into device usage patterns. Metrics included play session frequency, session duration, total usage minutes, and unique usage days for two powered mobility devices: Modified Ride-on Cars (MROC) and the Permobil Explorer Mini (EM). Twelve children with cerebral palsy used each device for eight consecutive weeks in home and community settings (16 weeks total), with device ordered randomized. Results showed no significant differences among tracking methods for the MROC. For the EM, only session duration differed between GPST and CRAL. Correlation analysis revealed variable relationships amongst tracking methods for both devices. The EM was used more frequently than the MROC, with significantly greater total usage minutes and session duration via CRAL, not GPST. The findings highlight the need for reliable tracking technologies that can be used across powered mobility devices.

Child, Preschool↗
PubMed1975

Animal psychophysics: improvements in the tracking method.

It is difficult to maintain stimulus control in animal psychophysical studies using the tracking method. Loss of stimulus control is characterized by wandering thresholds and responses in the absence of the stimulus. Rats were trained to make a variable number of licking responses to turn on an auditory stimulus. A response on a lever in the presence of the stimulus was reinforced with food. Two precedures were added to improve stimulus control. First, lever responses in the absence of the stimulus raised the intensity of the stimulus at the next presentation; second, rate of reinforcement in the threshold region was maintained at about the same level as that in the suprathreshold region by reducing the number of licking responses required to turn on the stimulus. Using these two procedures, stimulus control was improved and maintained and reliable auditory intensity thresholds were obtained.

Acoustic Stimulation↗
PubMed1979

Trialwise tracking method for measuring drug-affected sensory threshold changes in animals.

Rats and rhesus monkeys were trained under a multiple schedule, the components of which were random ratio schedules for food presentation and for shock presentation. The discriminative stimulus for the shock presentation component was a pure tone for the rats and a light for the rhesus monkeys. In the test session under the extinction condition for the shock presentation component, the intensity of the discriminative stimulus was successively either decreased by fixed units when the conditioned suppression was observed or increased when the conditioned suppression was not observed. The levels finally oscillated within a narrow range around the threshold. The auditory thresholds of rats were increased by intramuscular administration of quinidine at 20 mg/kg and also by repeated intramuscular administration of kanamycin at 250 and 500 mg/kg/day. In rhesus monkeys, visual thresholds were raised by application of pilocarpine at 0.02-0.16 mg/kg to the eyes and also by subcutaneous administration of LSD-25 at 4-8 micrograms/kg in one monkey and at 20-30 micrograms/kg in another. The method used for tracking the animals' sensory thresholds was sensitive enough to test the selective effect of the drugs and was also a relatively easy way to obtain a stable behavioral baseline for experimental purposes.

Animals↗
PubMed1977

Determination of uranium in human teeth, bones and tissues by the fission track method.

The uranium content of several human tooth, bone and soft tissue samples was determined by the fission tract method. The average uranium content in teeth, bones and soft tissues were 6.7, 8.4 and 64 ppb ash, respectively. The distribution of uranium in bones is less uniform than that of teeth, and the uranium content of soft tissues is generally higher than that of teeth and bone. The presence of thorium does not interfere with the uranium determination in most cases.

Bone and Bones↗
PubMed1992

An adaptive method for tracking voicing irregularities.

A method has been developed for tracking irregularities in the acoustic waveform of a sustained phonation using the adaptive Wiener filter. Irregularities are determined by the technique of correlation cancellation. The algorithm is evaluated using sustained vowels produced by a formant synthesizer and by subjects with and without phonatary disorders. Results indicate that the method is capable of differentiating between normal and abnormal voices. Most significantly, however, it can also track sporadic or nonstationary irregularities in the shape of an individual acoustic wavelet. This method is expected to be a useful tool for the acoustics analysis of voice production.

Adult↗
PubMed1976

A simple method of tracking mammals and locating triatomine vectors of Trypanosoma cruzi in Amazonian forest.

A simple method of tracking mammals from capture points to their refuges was developed to study Trypanosoma cruzi reservoir-vector associations in Belém forest. A device containing a spool of fine line was carried by released mammals so that the line unwound under minimum tension as the animal proceeded and could be followed the day after release. Twenty-three triatomine bugs of five species were found with 3 of 15 mammals retrieved.

Animals↗
PubMed1992

Tracking high-risk adolescents longitudinally.

Longitudinal tracking methods rarely have been documented. A discussion is provided here of tracking methods and strategies used in assessing the effectiveness of an AIDS prevention intervention with high-risk adolescents over four years. We demonstrated an ability to follow 92% of a sample of unstable youths in a difficult urban environment. Successful recontacting of youths depended on the structure of the project in the recruitment phases, strategic choice of interviewers, a cost-effective payment schedule and other motivators, knowledge of appropriate social service agencies that could provide information on youths, and methods to elicit cooperation. Confidentiality and other ethical issues are discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1978

Effects of instructional set on the comfortable loudness range.

Ten normal-hearing young adult subjects measured their Comfortable Loudness Ranges (CLRs) using two instructional sets. The first instructional set (range tracking) was similar to the Bekesy Comfortable Loudness tracking method described by Jerger and Jerger (1974). The second instructional set (limit tracking) required the subjects to perform separate trackings of each limit (upper and lower) of their CLRs. Results demonstrated a 34.4 dB difference between CLRs for the two instructional sets. The range tracking method yielded the narrowest CLR. Both instructional sets yielded similar upper limits of the CLR. The results of the present investigation demonstrate the importance of instructions employed in research and clinical measurements of the CLR.

Adult↗
PubMed1979

The effect of psychophysical method on the loudness of continuous and interrupted pure tones.

Using the Bekesy tracking method for loudness judgement tasks such as most comfortable loudness (MCL) and recalled loudness (RL) measurements, normal listeners have tracked continuous (C) tones at lesser intensities than interrupted (I) tones. The resulting continuous/interrupted (C/I) separations have ranged up to 22 dB. Explanations of the unexpected C/I separations have not been in agreement. The purpose of this study was to investigate whether psychophysical method has a significant effect on the C/I separation. Subjects were six normal-hearing adults, each of whom participated in three practice and ten test sessions of one hour each. Thirty-six experimental conditions were presented. The test signals were C tones, 200/200 msec I tones and 200/800 msec I tones, all at 1 kHz. The reference intensities wer 20, 50 and 80 dB SPL. The four methods were Bekesy tracking method (BTM), method of adjustment (MAdj), method of limits (ML) and method of constant stimuli difference (MCSD). Mean values for Point of Subjective Equality and C/I separation were calculated. C/I separations obtained with the BTM were significantly larger than C/I separations obtained with any other psychophysical method. These results demonstrate that C/I separations obtained during suprathreshold Bekesy tracking tasks by normal hearers are largely caused by the measurement method itself rather than by differences in C and I tone loudness. Time order errors could explain the BTM effect.

Adult↗
PubMed1991

A syntactic analysis method for sinusoidal tracking eye movements.

A syntactic method for the recognition of sinusoidal eye movements is presented. The method is based on a piecewise transformation of an eye movement signal to strings of a formal language and use of a formal grammar which generates the formal language. Gain and phase parameters of sinusoidal eye movements between a stimulus and its response are computed after the recognition of eye movements and after removing corrective saccades from the transformed signal. The method is used at an otoneurological laboratory.

Diagnosis, Computer-Assisted↗
PubMed1991

Itch and atopic dermatitis: clinical and experimental studies.

The aims of the study were to develop and evaluate methods for quantitative measurement of itch, to investigate the perception of itch in patients with atopic dermatitis (AD), and to measure itch in such patients during treatment with H1-receptor antagonists or cyclosporin A, thereby exploring possible mechanisms in the pathogenesis of itch in AD. In a double-blind, randomized, placebo-controlled, cross-over study of 30 AD patients using a potent, topical, antipruritic corticosteroid, two methods for measuring itch both successfully detected the itch-relieving effect of the corticosteroid. The two methods comprised new portable data-loggers (Pain-Track) for continuous recording of itch, and conventional visual analogue scale (VAS) forms for retrospective recording. The main advantages of the Pain-Track method are possibilities for frequent sampling, surveillance of compliance, and analysis of a large amount of data. Induction and measurement of experimental histamine-induced itch were studied in 38 healthy subjects. It was shown that pruritic stimuli should be presented in a random order so as to avoid systematic errors in the perception of itch. Two rating scales, a seven-stepped non-verbal scale on a Pain-Track logger, and a 100-mm VAS on a potentiometer, were found valid for continuous recording of itch. The perception of experimental itch was studied in 32 AD patients and 32 healthy controls. The itch responses provoked by wool fibres were significantly stronger in AD patients than in controls, whereas the histamine-induced dose-response curves for itch did not differ significantly between the two groups, who discriminated equally well between weak and strong histamine stimuli. No increased skin mast cell releasability was shown in vivo to compound 48/80 in AD patients. Their itch responses to the different pruritic stimuli did not correlate with clinical itch intensity, eczema score or serum IgE-level. In a double-blind, randomized, placebo-controlled, cross-over study of 25 AD patients, the effect on clinical itch of a sedative (clemastine) and of a non-sedative (terfenadine) antihistamine did not differ from that of placebo, although both drugs had a pronounced H1-receptor-antagonizing effect in the skin and clemastine was significantly sedative. These findings support the view that histamine is not the major pruritogen in AD, and that sedation is not necessarily associated with itch relief. In a double-blind, randomized, placebo-controlled, cross-over study of 10 AD patients, 10 days' treatment with cyclosporin A (CSA), 5 mg/kg/day, significantly reduced itch intensity, eczema score and the number of peripheral blood eosinophils.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1992

On the feasibility of pulse-echo speed of sound estimation in small regions: simulation studies.

Computer simulations are used to study the feasibility of the estimation of sound speed in small regions with precision better than 1% using the Beam Tracking method. The speed of sound is estimated in a 10-mm by 10-mm region by considering a number of parallel tracks confined to the small region. The transducer focusing and the step sizes for the tracking and tracked transducers required to extract the maximum amount of uncorrelated data from the 10-mm by 10-mm region is evaluated. The results show that the speed of sound can be estimated with error less than 1% in a small region using a typical medical transducer. The statistical comparison of estimates in small areas with different speed of sound is also considered.

Acoustics↗
PubMedDate not supplied

Automated local maximum-intensity projection with three-dimensional vessel tracking.

Despite the simplicity and widespread acceptance of the maximum-intensity-projection (MIP) technique for displaying three-dimensional (3D) magnetic resonance angiographic data, several disadvantages are associated with MIP as it is applied to all of the 3D data. These include elevated noise level, reduced contrast between small vessels and background tissue, and the inability to distinguish arteries from veins. The authors have developed a 3D vessel tracking method combined with a local MIP around a given vessel to complement conventional MIP and alleviate these problems. The method is referred to as a traveling MIP (TMIP). TMIP was evaluated in both patients and healthy volunteers. The results indicate that TMIP provides better contrast between vessels and background tissue, better lumen definition, and better vascular visualization than either MIP or vessel tracking alone.

Algorithms↗
PubMed1991

Single particle tracking. Analysis of diffusion and flow in two-dimensional systems.

Analysis of the trajectories of small particles at high spatial and temporal resolution using video enhanced contrast microscopy provides a powerful approach to characterizing the mechanisms of particle motion in living cells and in other systems. We present here the theoretical basis for the analysis of these trajectories for particles undergoing random diffusion and/or systematic transport at uniform velocity in two-dimensional systems. The single particle tracking method, based on observations of the trajectories of individual particles, is compared with methods that characterize the motions of a large collection of particles such as fluorescence photobleaching recovery. Determination of diffusion coefficients or transport velocities either from correlation of positions or of velocities of the particles is discussed. A result of practical importance is an analysis of the dependence of the expected statistical uncertainty of these determinations on the number of position measurements. This provides a way of judging the accuracy of the diffusion coefficients and transport velocities obtained using this approach.

Diffusion↗