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At least 91 records · Page 5Linked to original sources
PubMed1982

Inverse frequency dependence of simultaneous tone-on-tone masking patterns at low levels.

Using the Békésy tracking method, tone-on-tone masking patterns were measured with eight subjects at eight masker frequencies between 250 Hz and 6.03 kHz. Masking patterns were obtained for five masker levels between 20 and 60 dB SPL. Test-tone frequencies were chosen within two critical bands above and below the masker frequency. A level-dependent frequency asymmetry of masking was observed at all masker frequencies except at 250 Hz. At low levels there was a greater spread of masking towards the lower frequencies than toward the higher frequencies, but at high levels there was a greater spread of masking towards the higher frequencies than toward the lower frequencies. Only at masker levels of 40 dB SPL were the masking patterns approximately symmetrical.

Auditory Threshold↗
PubMed1984

Receiving beam patterns and directivity indices of the Atlantic bottlenose dolphin Tursiops truncatus.

The receiving beam patterns of an Atlantic bottlenose dolphin was measured in both the vertical and horizontal planes for frequencies of 30, 60, and 120 kHz. Measurements in the vertical plane were performed by training the dolphin to rotate on its side and station on a vertically oriented biteplate device. A signal source was positioned 3.5 m directly in front of the animal on an arc while the position of a broadband noise source was varied in azimuth along the arc, with the animal stationed at the origin of the arc. Using a go/no-go response procedure, the masked threshold of the dolphin was determined by varying the intensity of the noise source via a tracking method of stimulus presentation, for different azimuth's of the noise source. Measurements in the horizontal plane were obtained with the dolphin stationing on a horizontal biteplate. Two masking noise sources, projecting equal levels of uncorrelated noise, were located at +/- 20 degrees on either side of the arc midpoint. The levels of the noise source were held constant and the masked thresholds determined by varying the level of the signal source while positioned at different azimuths along the arc. Results indicated that maximum sensitivity in the vertical plane (the major axis of the beam) occurred between 5 degrees and 10 degrees above the midline of the animal's mouth and that the beam patterns were not symmetrical about the major axis. The sensitivity dropped off more quickly with increasing angle above the head than below. The beam patterns in the horizontal plane were directed forward and were fairly symmetrical about the midline of the animal's body.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Individual differences in auditory capabilities. I.

Twenty-eight audiometrically normal adult listeners were given a variety of auditory tests, ranging from quiet and masked thresholds through the discrimination of simple and moderately complex temporal patterns. Test-retest reliability was good. Individual differences persisted on a variety of psychoacoustic tasks following a period of training using adaptive threshold-tracking methods, and with trial-by-trial feedback. Large individual differences in performance on temporal-sequence-discrimination tasks suggest that this form of temporal processing may be of clinical significance. In addition, high correlations were obtained within given classes of tests (as, between all tests of frequency discrimination) and between certain classes of tests (as, between tests of frequency discrimination and those of sequence discrimination). Patterns of individual differences were found which support the conclusion that individual differences in auditory performance are, in part, a function of patterns of independent abilities.

Adolescent↗
PubMed1995

Modulation of microtubule dynamic instability in vivo by brain microtubule associated proteins.

Heat-stable brain microtubule associated proteins (MAPs) and purified microtubule associated protein 2 (MAP-2) were microinjected into cultured BSC-1 cells which had been previously injected with rhodamine-labeled tubulin. The dynamic instability behavior of individual microtubules was then examined using low-light-level fluorescence microscopy and quantitative microtubule tracking methods. Both MAP preparations suppressed microtubule dynamics in vivo, by reducing the average rate and extent of both growing and shortening events. The average duration of growing events was not affected. When measured as events/unit time, heat-stable MAPs and MAP-2 did not significantly alter the frequency of rescue; the frequency of catastrophe was decreased approximately two-fold by heat-stable MAPs and MAP-2. When transition frequencies were calculated as events/unit distance, both MAP preparations increased the frequency of rescue, without altering the frequency of catastrophe. The percentage of total time spent in the phases of growth, shrink and pause was determined. Both MAP-2 and heat-stable MAPs decreased the percentage of time spent shortening, increased the percentage of time spent paused, and had no effect on percentage of time spent growing. Heat-stable MAPs increased the average pause duration, decreased the average number of events per minute per microtubule and increased the probability that a paused microtubule would switch to growing rather than shortening. The results demonstrate that addition of MAPs to living cells reduces the dynamic behavior of individual microtubules primarily by suppressing the magnitude of dynamic events and increasing the time spent in pause, where no change in the microtubule length can be detected. The results further suggest that the expression of MAPs directly contributes to cell type-specific microtubule dynamic behavior.

Animals↗
PubMed1977

A simultaneous discrimination procedure for the measurement of vision in nonverbal children.

Few nonverbal developmentally disabled children ever receive adequate vision assessment because of their limited language skills. The present study details a simultaneous discrimination procedure for measuring subjective visual acuity in such children. A stimulus fading procedure was used to train a discrimination between Snellen Es differing in orientation, and a psychophysical tracking method was used to determine acuity thresholds. The procedure was tested with 11 nonverbal autistic and schizophrenic children and validated with four nonpsychotic children. Eight of the psychotic children were successfully examined in one to three sessions. Two of these children were identified as having significant acuity losses. The validity assessment showed that the experimental procedure resulted in thresholds equal to or slightly lower than those obtained with the Illiterate E chart.

Adolescent↗
PubMed1989

MR angiography and dynamic flow evaluation of the portal venous system.

We studied the value of MR angiographic techniques in imaging the portal venous system. Projection angiograms were created by postprocessing a series of two-dimensional, flow-compensated gradient-echo images. Flow velocity was determined by a bolus-tracking method with radiofrequency tagging and multiple data readout periods. Each image was acquired during a breath-hold. MR angiography was applied to six normal subjects and four patients with abnormal hemodynamics in the portal venous system. Flow velocity determined by MR was correlated with the results of duplex sonography. The main portal vein and intrahepatic branches were shown in all cases. Portosystemic collaterals were identified in all patients with portal hypertension. In normal subjects, peak flow velocities (17.9 +/- 2.8 cm/sec) on MR correlated well with values determined by duplex sonography (17.5 +/- 2.2 cm/sec) (r = .846, p less than .04). Reversed portal blood flow was shown in two patients. One patient with portal vein thrombosis had no evidence of flow by MR angiography. Our results indicate that MR angiography can provide a three-dimensional display of normal and abnormal vascular anatomy as well as functional information in the portal venous system.

Blood Flow Velocity↗
PubMed1982

Uranium content in porcelain denture teeth and in porcelain powders for ceramic crowns.

Some porcelain denture teeth and porcelain powders marketed in Sweden haven been analyzed for the content of uranium. The fission track method and the delayed neutron technique were the methods used. Compared to results published previously the content of uranium was generally found to be lower in the brands analyzed. The denture teeth contained 23-186 ppm for Anatoform, 35-137 ppm for Myerson, 15-45 ppm for Candulor G and 20-53 ppm for Vivopearl. The baked and fired porcelain powders showed values of about 2.8 ppm at most, those in the form of powder about 25 ppm at most. The radiation dose to the mucosa of the upper lip was calculated and is discussed.

Crowns↗
PubMed1986

Concentration and particle-size distribution of uranium and some trace elements in airborne dust collected in Tsukuba.

Uranium and some other trace elements were determined in the size-separated airborne dust collected in Tsukuba with an Andersen-type high-volume cascade impactor. The fission track method and the instrumental neutron activation method were applied to the determination of uranium and other elements, respectively. Selenium, antimony, arsenic and zinc were found to be rich in particulates of smaller size, while scandium, iron and cobalt showed a reverse trend, depending on their main origins, i.e. whether industrial or terrestrial. Uranium was distributed in both the larger and smaller particles to the same extent, suggesting that it is derived from both the terrestrial and artificial sources.

Dust↗
PubMed1987

Distribution of uranium in human lungs.

Several human lung samples were dissected into lobes and uranium and silicon contents in each lobe were determined by the fission track method and the inductively coupled plasma-atomic emission spectrometry (ICP-AES), respectively. It was found that both uranium and silicon concentrations were high in the upper lobe compared with those in the lower one. Though the tendency may be mainly interpreted by the deposition way of airborne dust in the lung, the higher U/Si concentration ratio in the upper part than that in the lower part of lungs may suggest the partial removal of uranium deposited in the lower part of the tissue.

Air Pollution, Radioactive↗
PubMed1987

Distribution of uranium in human bones.

Uranium and calcium contents in human bones (skull, rib and femur) were determined by the fission track method and the inductively coupled plasma-atomic emission spectroscopic method (ICP-AES), respectively. The U/Ca concentration ratio in the bones was found to decrease in the order of rib greater than femur greater than skull, which is in accordance with the decreasing order of the mean annual replacement percentage of bone components. Several femur bones were cut into several longitudinal segments, and uranium and calcium contents in each segment were determined. Among these, the U/Ca ratio in the epiphysis was higher than those in the diaphysis.

Adult↗
PubMed1987

Plutonium and uranium in Japanese human tissues.

Plutonium and uranium in human tissues obtained from residents of the Tokyo area were determined by a-spectrometry and the fission track method, respectively. The distribution pattern of each element was estimated on the basis of mean concentration obtained. Plutonium is concentrated in some special organs, while uranium is distributed rather generally throughout the whole body. This difference of distribution tendency is considered to be due to the characteristics of stable chemical states of the elements in body fluid; Pu4+ for plutonium and UO2(2+) for uranium.

Asian People↗
PubMedDate not supplied

Biocybernetic investigations of pursuit and posture motor control--a strategy for a detailed characterization of movement disorders in brain-damaged children.

By means of a biocybernetic approach the pursuit and posture motor control of brain-damaged children with spastic hemiparesis and disturbed motor coordination of mild extent were investigated. The postural motor control system was loaded by pseudostochastic binary torque sequences applied to the wrist. The dynamics of this system were characterized on the basis of the parameters forearm displacement as well as surface-EMG of M. Biceps and Triceps (calculations of weight functions). The pursuit motor control was analyzed by a pursuit tracking method. By this way the motor capacity for fine and rough motor coordination, motor rhythm, motor adaptation, the maximal speed of movements and motor reaction time could be tested. Considering these results a characterization of movement control on different levels of motor regulation was possible (dynamics of muscular, spinal, and supraspinal components of motor control).

Brain Damage, Chronic↗
PubMed1989

[Analysis of oculomotor disorders in motor neuron disease].

Oculomotor disorders have been considered to be one of the negative symptoms in motor neuron disease (MND). However, recently, ophthalmoplegia, abnormal Bell's phenomenon and disturbance of pursuit movement have been reported. We tried to evaluate 32 patients with MND (19 males and 13 females; age, 35 to 77 years; 52.4 +/- 10.1 years) by bedside examination and electro-oculography (EOG) using an eye tracking method. Twenty-three of them were classified as amyotrophic lateral sclerosis (ALS) and seven as bulbospinal muscular atrophy, and two were unclassified. One hundred healthy persons for bedside examination and twenty-two for EOG were investigated as controls. Findings by bedside examinations were as follows; 1) Slight limitations of upward only, up & downward and upward & horizontal gaze were observed in 5 cases (15.6%), 1 case (3.1%) and 1 case (3.1%), respectively. 2) Incomplete convergence was observed in 11 cases. (34.4%) 3) Horizontal gaze nystagmus was observed in 6 cases. (18.8%) 4) As regards the frequency of limitation of upward gaze and incomplete convergence, there were no statistically significant differences from those in controls. Electrooculographic results were: 1) square wave jerks (SWJs) were recorded in 3 cases. (9.4%) 2) Amplitude ratio of saccade was significantly higher in MND than that in controls with the risk less than 0.1%. 3) The degree of ocular dysmetria was significantly higher in MND than that in controls with the risk less than 0.5%. These abnormalities were not directly related to suffering period. Although the mechanism is not known, several reports of the effectiveness of thyrotropin releasing hormone (TRH) in ALS were recently published.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[Ocular motor abnormalities in progressive supranuclear palsy].

Eleven patients, 7 males and 4 females, of progressive supranuclear palsy (PSP) were examined neuro-otologically for the purpose of elucidating the characteristics of ocular motor abnormalities. All cases were admitted to our hospital and age at onset was from 52 to 71 years old, duration of illness was 2 to 11 years. Range of voluntary eye movements and abnormal eye movements including nystagmus were examined on naked eyes and with electronystagmography (ENG). Smooth pursuit movements and saccadic eye movements were tested both horizontally and vertically by using visual tracking method with ENG recordings. Optokinetic nystagmus test and caloric test with visual suppression test were also performed. These neurotological examinations were made repetitively in 5 cases and their progressions were observed. Vertical gaze palsy and convergence palsy were observed in all cases as the initial symptom. In this study downward gaze was more severely disturbed than upward gaze. Using ENG, saccadic eye movements (saccades) were disturbed earlier than smooth pursuit movements. Hypometric saccades and decreased saccadic velocity were common abnormalities. In the later stage of the disease, horizontal eye movements were also disturbed. In four cases bilateral adduction palsy was added to vertical gaze paralysis so that the lesion of the MLF to oculomotor nucleus was suggested to exist. These voluntary eye movements were worsened gradually as the disease progressed. By using ENG we could find so called abnormal eye movements more frequently than the previous reports. Eight patients demonstrated horizontal gaze nystagmus, and rebound nystagmus were observed in four cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1986

[Organization of the median and intralaminar nuclei of the thalamus: hypotheses on their role in the onset of certain central pain].

Afferent neurons from thalamic median and intralaminar (IL) nuclei arise in the spinal cord, brain stem synapses, substantia nigra, internal pallidum and cerebral cortex, directly and through the intermediary of the reticular nucleus of the thalamus (RT). Efferent neurons terminate in the anterior thalamic nuclei, RT, striatum and cerebral cortex. Tracking methods in the rat have demonstrated that some RT neurons which project towards the IL are surrounded by endings from the posterior ventral nucleus (VP). Electrical stimulation of multiple prosencephalic structures (mainly VP) and of sensory pathways induce responses in IL of brief latency followed by inhibition. Whereas the responses appear to be related to activation of excitatory projections (under the tonic facilitating control of cerebral cortex) the inhibition phases could be related to activation of RT, since they disappear after lesion of the RT. This nucleus could act as a common final pathway of inhibitions exerted on IL in the rat. Studies in this species have demonstrated that a lateral lesion of the thalamus that includes the RT provokes the appearance in IL of abnormal neuronal hyperactivity of a tonic nature and yet still exaggerated by stimuli normally capable of inducing responses of brief duration followed by inhibition. Human studies using a tomoscintigraphic method to determine regional blood flow have shown "hyperactivity" of the thalamic region in patients with pain of central origin during a natural stimulus provoking hyperpathia. This was not observed during painful states without hyperpathia. The working hypothesis proposed is that of a central lesion inducing a hyperpathia provoking pathologic hyperactivity in certain thalamic nuclei.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Orientation in birds. Satellite tracking: a new method in orientation research.

The study of bird migration by satellite tracking began in the 1980s, after transmitters had become sufficiently small to allow the monitoring of larger migrating species. The initial studies in this direction were all successful with respect to establishing this method (Section 2) of elucidating new migration patterns and various aspects of orientation. These pilot studies are summarized in Section 3, Table 1, Figures 1-4. We believe that studies on avian orientation and navigation will, in general, greatly benefit from satellite tracking if some prerequisites are fulfilled and adequate experiments planned (Section 4). In future studies, smaller transmitters with increased life expectancies are needed, and possible effects of these transmitters on bird behaviour must be examined. Considerable improvement of satellite tracking in avian orientation research is to be expected, along with the development of a new generation of satellites allowing communication between satellites and transmitters (Sections 4, 5).

Animals↗