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PubMed1994

Measurements of the acoustic input impedance of cat ears: 10 Hz to 20 kHz.

The acoustic input impedence of the ear is a useful measure of the behavior of the middle ear and of its effect on the acoustics of the external ear. A high-impedance acoustic source with an integral microphone was designed for acoustic-impedance measurements. The source's Norton equivalent circuit was determined from measurements of the sound pressure it generated in known acoustic loads. Tests on simple acoustic configurations show errors in impedance measurements of less than 10% in magnitude and 7 degrees in angle over a frequency range from 10 Hz to 10 kHz with increasing errors at higher frequencies. Measurements at the tympanic membrane (TM) on five cat ears with widely opened middle-ear cavities show an impedance that is compliance-like below 0.3 kHz and approximately resistive above 2 kHz. With the cavities intact the impedance magnitude is somewhat larger for low frequencies, has a sharp maximum near 4 kHz, and at the highest frequencies is little affected by the state of the cavities. Impedance magnitude varies among ears by a factor of 3. The pressure reflection-coefficient that is determined from the impedance is frequency dependent with magnitude between 0.2 and 1. To characterize the motion transformation of the TM we calculate the ratio of tympanic-membrane volume velocity to the velocity of the mallear umbo, called here the kinematic area ATK. This complex quantity is constant with an angle of zero for frequencies below 0.6 kHz, but at higher frequencies both magnitude and angle of ATK vary with frequency.

Acoustic Impedance Tests↗
PubMed2002

Development of force control and timing in a finger-tapping sequence with an attenuated-force tap.

We conducted an experiment to examine age-related differences in the control of force and timing in a finger-tapping sequence with an attenuated-force tap. Participants between 7 and 20 years old tapped on a load cell with feedback on practice trials. They were required to recall the force pattern (300 g, 300 g, 300 g, 100 g) and the intertap interval (400 ms) without feedback on test trials. Analysis indicated that the last attenuated tap affected the first three taps of the tapping sequence in adults and adolescents but not in children. Adults and adolescents appeared to respond with four taps as a chunk, resulting in a contextual effect on the timing of force control, but younger children had difficulty with such chunking. Further, adults and adolescents were able to more accurately produce individual force magnitudes to match target magnitudes than younger children. For the ratio of force in serial positions 1:4, 2:4, and 3:4, consequently, 7- to 8-year-old children had lower ratios than the other age groups. Although there was no difference among age groups for timing control of peak force to press duration as a control strategy of force, 7- to 8-year-old children spent more time to produce force than the other age groups. Peak force with a decreased force was more variable in the attenuated force serial position (4) than in the other serial positions in all five age groups. Peak force variability was particularly robust in younger children. These findings suggest that younger children have difficulty with both temporal and spatial (i.e., magnitude) components of force control.

Adolescent↗
PubMed1971

Basic drives.

Explore the source record for details and available documents.

Age Factors↗
PubMed2003

Spatial representation of predictive motor learning.

A key feature of skilled motor behavior is the ability of the CNS to predict the consequences of its actions. Such prediction occurs when one hand pulls on an object held in the other hand; the restraining hand generates an anticipatory increase in grip force, thereby preventing the object from slipping. When manipulating a novel object, the CNS adapts its predictive response to ensure that predictions are accurately tuned to the dynamics of the object. Here we examine whether learning to predict the consequences of an action on a novel object is restricted to the actions performed during manipulation or generalizes to novel actions. A bimanual task in which subjects held an object in each hand and the relationship between actions on one object and the motion of the other could be computer controlled from trial-to-trial was used. In four conditions we varied the spatial relationship between the direction of force subjects applied to the left-hand object and the consequent direction of motion of an object held in their right hand, which subjects were required to restrain. The results show that predictive learning was local to the direction of forces experienced during learning and that the magnitude of predictive responses was greatly reduced for novel directions of action of the left hand. The pattern of generalization shows that the representation of predictive learning is spatially local and can be approximated as having a spatially narrow Gaussian basis function.

Conditioning, Psychological↗
PubMed2006

Edge integration and the perception of brightness and darkness.

How do induced brightness and darkness signals from local and remote surfaces interact to determine the final achromatic color percept of a target surface? An emerging theory of achromatic color perception posits that brightness and darkness percepts are computed by weighting and summing the induction signals generated at edges in a scene. This theory also characterizes how neighboring edges interact to modulate the gain of brightness and darkness signals induced from one another. Here we assess evidence for this edge integration theory by means of computational modeling and a psychophysical experiment. We quantitatively show how local and remote edge induction signals in disk-ring displays give rise to either contrast or assimilation effects. Spatial integration of same-polarity edge signals supports a contrast effect, whereas integration of opposite-polarity signals supports an assimilation effect, particularly when the remote induction signal is much stronger than the local induction signal. The results confirm a key prediction of edge integration theory, namely, that strong assimilation effects can lead subjects to ignore the polarity of local edge information when setting achromatic color matches. The conditions necessary for strong assimilation effects are also associated with greater difficulty in setting matches, suggesting that caution is required when interpreting matching data in terms of gain control. We describe several avenues for further study of contrast, assimilation, and gain control.

Adult↗
PubMed1988

Perceptions held by obese children and their parents: implications for weight control intervention.

The study was designed to identify some of the psychosocial barriers to compliance in a hospital-based weight control intervention program for adolescents. Forty obese adolescents, 10 to 16 years of age, and their parents were surveyed prior to participation in a behavioral change weight control program at a major teaching hospital. Significant correlations were obtained between weight loss outcome and six factors. In obese adolescents, weight loss was significantly associated with their beliefs regarding: (1) personal control over weight, (2) barriers or difficulty of losing weight, (3) medical problems as a cause of their obesity, (4) family problems as a cause of their obesity, and (5) perceived willingness of family members to diet. It is suggested that greater weight loss in children who perceived more barriers/difficulty and less family willingness to diet may reflect the importance of having realistic expectations related to behavioral compliance. In addition, a positive parental attitude or expectation that the child was less likely to be overweight in the future was associated with greater weight loss compliance. Other parental health beliefs, however, did not generally predict the child's weight loss response to the intervention. The findings lend support to the significance of the adolescent's beliefs regarding weight and family support in explaining weight loss response to a behavioral change intervention program.

Adolescent↗
PubMed1998

How body size affects middle-ear structure and function and auditory sensitivity in gekkonoid lizards.

Gekkonoid lizards increase in body size throughout life, and the present study investigates whether changes in auditory function accompany these increases. Middle-ear structures in four groups of animals, adults and juveniles of two gekkonoid species (Eublepharis macularius and Oedura marmorata), were examined. Tympanic membrane velocity and phase were also measured in all four groups. An indication of peripheral auditory function was obtained for each group by measuring compound action potentials (CAPs) from the round window membrane. The middle-ear contribution to CAP thresholds was obtained by comparing threshold levels of the CAP response with and without an intact middle-ear system. The results from these studies indicated that significant changes occurred in middle-ear structure, tympanic membrane velocity and CAP threshold between the younger and older animals. In addition, the adults of both species exhibited better auditory function when the acoustic stimulus was delivered to the tympanic membrane than when it was delivered to the columella footplate. The findings show clearly that increased body size (or age) is accompanied by functional changes in the auditory periphery.

Action Potentials↗
PubMed1990

Effect of alcohol on sensory and sensorimotor visual functions.

The literature on the effect of alcohol on sensory and sensorimotor visual functions is extensive. The findings are often contradictory and early studies did not correlate the effects with blood alcohol levels. This study was designed to test the effects of alcohol on various visual functions using equipment that is freely available to the clinician. A significant loss of visual field, accommodation and convergence that correlated with increasing blood alcohol levels was found. Visual acuity, color vision and stereoacuity were not significantly altered by alcohol.

Accommodation, Ocular↗
PubMed1971

Evidence of interaction between deprivation effects and stimulus control.

Discriminative responding in pigeons was studied under multiple variable-interval extinction and variable-ratio extinction schedules, as deprivation was varied. Generally, the greater the accuracy of discrimination that developed during training, the smaller the effect of deprivation upon subsequent performance. This was true both in terms of changes in response rates, and in the relationship between response rates during food reinforcement and extinction. When discrimination was inaccurate, increases in deprivation resulted in disproportionate increases in responding during extinction, as compared to increases during food reinforcement components of the schedule. The results suggest that as stimulus control (accuracy) of responding increases, discriminative performance becomes less and less susceptible to influence by deprivation.

Acoustic Stimulation↗
PubMed2004

The effectiveness of Web-based vs. non-Web-based interventions: a meta-analysis of behavioral change outcomes.

BACKGROUND: A primary focus of self-care interventions for chronic illness is the encouragement of an individual's behavior change necessitating knowledge sharing, education, and understanding of the condition. The use of the Internet to deliver Web-based interventions to patients is increasing rapidly. In a 7-year period (1996 to 2003), there was a 12-fold increase in MEDLINE citations for "Web-based therapies." The use and effectiveness of Web-based interventions to encourage an individual's change in behavior compared to non-Web-based interventions have not been substantially reviewed. OBJECTIVE: This meta-analysis was undertaken to provide further information on patient/client knowledge and behavioral change outcomes after Web-based interventions as compared to outcomes seen after implementation of non-Web-based interventions. METHODS: The MEDLINE, CINAHL, Cochrane Library, EMBASE, ERIC, and PSYCHInfo databases were searched for relevant citations between the years 1996 and 2003. Identified articles were retrieved, reviewed, and assessed according to established criteria for quality and inclusion/exclusion in the study. Twenty-two articles were deemed appropriate for the study and selected for analysis. Effect sizes were calculated to ascertain a standardized difference between the intervention (Web-based) and control (non-Web-based) groups by applying the appropriate meta-analytic technique. Homogeneity analysis, forest plot review, and sensitivity analyses were performed to ascertain the comparability of the studies. RESULTS: Aggregation of participant data revealed a total of 11,754 participants (5,841 women and 5,729 men). The average age of participants was 41.5 years. In those studies reporting attrition rates, the average drop out rate was 21% for both the intervention and control groups. For the five Web-based studies that reported usage statistics, time spent/session/person ranged from 4.5 to 45 minutes. Session logons/person/week ranged from 2.6 logons/person over 32 weeks to 1008 logons/person over 36 weeks. The intervention designs included one-time Web-participant health outcome studies compared to non-Web participant health outcomes, self-paced interventions, and longitudinal, repeated measure intervention studies. Longitudinal studies ranged from 3 weeks to 78 weeks in duration. The effect sizes for the studied outcomes ranged from -.01 to .75. Broad variability in the focus of the studied outcomes precluded the calculation of an overall effect size for the compared outcome variables in the Web-based compared to the non-Web-based interventions. Homogeneity statistic estimation also revealed widely differing study parameters (Q(w16) = 49.993, P < or = .001). There was no significant difference between study length and effect size. Sixteen of the 17 studied effect outcomes revealed improved knowledge and/or improved behavioral outcomes for participants using the Web-based interventions. Five studies provided group information to compare the validity of Web-based vs. non-Web-based instruments using one-time cross-sectional studies. These studies revealed effect sizes ranging from -.25 to +.29. Homogeneity statistic estimation again revealed widely differing study parameters (Q(w4) = 18.238, P < or = .001). CONCLUSIONS: The effect size comparisons in the use of Web-based interventions compared to non-Web-based interventions showed an improvement in outcomes for individuals using Web-based interventions to achieve the specified knowledge and/or behavior change for the studied outcome variables. These outcomes included increased exercise time, increased knowledge of nutritional status, increased knowledge of asthma treatment, increased participation in healthcare, slower health decline, improved body shape perception, and 18-month weight loss maintenance.

Adult↗
PubMed2003

Covariation of sex differences in mental rotation with body size.

Sex difference in mental rotation ability was reconsidered. The Vandenberg-Kuse figures were administered to 120 male and 76 female students from the Medical School of BlackSea Technical University in Trabzon, Turkey to assess the mental rotation ability. Students' height and weight were measured. As expected, men outperformed women on this test and had greater height and weight. Number correct on mental rotation test significantly correlated with height and weight for the total sample and for men, but only with weight for women. Using weight as covariate, the sex difference was no longer significant. The mean mental rotation score was significantly higher for heavy women than for light men. There was a positive correlation between weight and mental rotation test scores for heavy women, but height and weight were negatively correlated with mental rotation test scores for light men. These results suggest that there is no sex difference in mental rotation ability as measured.

Adolescent↗
PubMedDate not supplied

[Effect of monochromatic light on the growth and development of larva of the brown frog Rana temporaria L].

Acceleration of the growth and development of R. temporaria larvae under the effect of short-wavelength light was observed in experiments. However, the highest linear and weight parameters of postmetamorphic juveniles were recorded upon exposure to yellow and green light, and the lowest parameters, upon exposure to blue light. The red zone of the light spectrum had no apparent effect on the development of tadpoles and juvenile frogs.

Animals↗
PubMed2006

Maternal estimation of fetal weight as a complementary method of fetal weight assessment: a prospective clinical trial.

OBJECTIVE: To assess the accuracy of fetal weight estimations performed by parturients vs. clinical and sonographic estimates. graphic estimates. STUDY DESIGN: Term parous women were included in this prospective trial. Each woman estimated the weight of her fetus. Fetal weight was also estimated sonographically and clinically. The clinical evaluations were performed by an attending gynecologist and a resident. Estimate accuracy for extreme fetal weights was evaluated separately. RESULTS: We enrolled 128 women. Maternal and resident estimations' accuracy was identical. The attending physician estimates were superior to the residents' and parturients', with a mean absolute error of 318 g and 67% of the evaluations within the 10% boundaries of the actual birth weight. Sonographic evaluation was the most accurate method, with a mean absolute error of 244 g and 76% of evaluations within 10% of the actual birth weight. When partitioned to extreme fetal weight groups (upper and lower 10th percentiles), the maternal evaluation was at least as accurate as the clinical evaluations of both the attending and resident. CONCLUSION: Maternal evaluation of the fetus's weight is as accurate as physicians' clinical estimations, and is advised as a complementary method of assessment. This estimation may greater relevance when intrauterine growth restriction or macrosomia is suspected.

Body Weights and Measures↗