Biomedical subjects
C J Brown
Publications and source records attributed to C J Brown.
Masking-level difference in filtered-random and amplitude-modulated noise.
The masking characteristics of filtered-random noise and amplitude-modulated noise (40-dB pressure-spectrum level) were studied in a series of four experiments using a masking-level difference paradigm, that is, 500-Hz thresholds in S0N0 and SpiN0 binaural conditions. In Experiment 1 a filtered noise (200-800 Hz) and an amplitude-modulated noise (425-575 Hz) produced equal thresholds in S0N0; for SpiN0, however, the thresholds in amplitude-modulated noise were 1.6 dB lower than were the thresholds in filtered noise. In Experiment 2 S0N0 and SpiN0 thresholds were established in three filtered noise bandwidths (200-800 Hz, 335-685 Hz, and 410-600 Hz) and in the amplitude-modulated noise (425-575 Hz). When the bandwidths of the filtered-random and amplitude-modulated noises were similar, the SpiN0 thresholds were the same but the S0N0 thresholds were different. Experiments 3 and 4 indicated that with amplitude-modulated noise when the zero amplitude crossings of the tone and the noise coincided, the S0N0, SpiN0, and SmNm thresholds were 1.2-2.0 dB higher than were the thresholds when the zero crossings of the tone and noise did not coincide. The data indicate that the masking characteristics of filtered-random noise and amplitude-modulated noise are different. The findings are interpreted as an indication that perceptual phenomena depend on the temporal characteristics as well as the power spectrum of the signal and masker.
Employee assistance I. Building an in-house service.
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Target portion of marketing efforts to public: surveys.
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A proposal for a monitoring and aversive feedback device to maintain drug abstinence or controlled drug use.
A device implanted in a patient could monitor blood levels of addictive substances on an intermittent or continuous basis. Excessive levels of a given substance would trigger release of an aversive chemical agent into the bloodstream, in essence creating an artificial allergy. Implications of the concept are discussed.
Evidence that calmodulin is in the chloroplast of peas and serves a regulatory role in photosynthesis.
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Hospital management of chronic illness in adolescence: a development model.
Attaining adulthood has always been a difficult process in the management and guidance of our adolescent populations. The stress of chronic illness during this developmental stage cna complicate an already overpowering dilemma in adolescents struggling for independence. Too often, health care professionals react to the adolescent patient out of context. In managing their care, it is important to understand the framework of child development theory and also become aware of our own feelings in relating to adolescents. Adolescents have their own concepts of illness and hospitalization that must be assessed in formulating a comprehensive management plan. Taking all of these dynamics into account, hospital staff can present a more educational and preventative approach that involves that adolescent in helping him cope with his development during a vulnerable time.
Heritabilities for regression and progression of rous sarcomas in the chicken.
Variance components for hatch, line, and sire expressed as percentages of the total variance for each parameter of regression and progression of Rous sarcomas in chickens were obtained. Some parameters measured specific stages of regression or progression, and other parameters measured the entire process of regression or progression of Rous sarcomas. Heritabilities of each parameter were estimated. Additive genetic variation is strongly implicated in the defense of the chicken against early tumor growth and during the entire process of regression. Environmental variation is important in influencing the point in time of tumor growth when the first reduction in size of tumor occurs. There is evidence of genetic variation exclusive of the R-Rs-1 gene locus that assists the chicken to resist tumor growth. The coefficient of variation for each of the parameters is very large as compared with the coefficient of variation for economic traits such as body weight at broiler age.
Neonatal mortality review: a basis for improving care.
Neonatal deaths in Iowa were reviewed to assess educational needs at each of the three levels of care. The review was oriented toward a clinical rather than a pathologic impression of cause of death. Five major categories of disease accounted for 90% of the deaths surveyed in the two years reported, 1978 and 1979. They were: congenital anomalies, birth weight less than or equal to 750 gm, respiratory distress syndrome, bacterial sepsis, and asphyxia. Defects in the care system were noted and remedial measures suggested. Based on the mortality data accumulated, an idealized neonatal death rate was calculated, and from this, an estimate of potentially salvageable deaths was offered. Small hospitals with low neonatal death rates were found to be an important source of potentially preventable deaths. Other states and regions interested in evaluating a regionalized system of perinatal health care may wish to consider a review of causes of neonatal deaths similar to the approach illustrated for Iowa.
Vocational rehabilitation for dialysis and transplant patients.
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Thirst and vasopressin release in the dog: an osmoreceptor or sodium receptor mechanism?
The effects of intravenous infusion of hypertonic NaCl, sucrose, glucose, urea, or isotonic NaCl solution on thirst and plasma arginine vasopressin concentration (AVP) were studied in five conscious dogs. The changes in osmolality and sodium concentration of plasma and cerebrospinal fluid (CSF) were measured at the threshold of drinking, or after 45 min if no drinking occurred. Hypertonic NaCl and sucrose stimulated drinking in all dogs and significantly elevated plasma AVP. Equally hypertonic glucose, urea, or isotonic NaCl failed to stimulate any drinking or vasopressin secretion. All hypertonic solutions caused significant and similar increases in the osmolality and sodium concentration of CSF. Plasma osmolality was increased by the hypertonic solutions. Plasma sodium was increased by hypertonic NaCl, decreased by sucrose and glucose, and not changed by urea. Isotonic NaCl had no effect on either plasma or CSF composition. These data are not consistent with either a sodium or an osmoreceptor mechanism located within the blood-brain barrier (BBB) or with a peripheral sodium receptor mechanism. An intracranial osmoreceptor located on the blood side of the BBB is proposed to explain these results.
Drinking and vasopressin release during ventricular infusions of hypertonic solutions.
Six dogs were administered third ventricular infusions of artificial cerebrospinal fluid (CSF) (292 mosmol/l) alone or artificial CSF to which neither NaCl, sucrose, glucose, or urea was added to yield a final osmolar concentration of 500 mosmol/l. The volume of water drunk during 45 min of infusion was measured and blood was sampled for determination of plasma vasopressin concentration at 15-min intervals. Artificial CSF made hypertonic by addition of NaCl or sucrose stimulated water intakes of 9.0 +/- 3.2 ml/kg (mean +/- SE) and 7.3 +/- 3.7 ml/kg, respectively. There was no statistical difference in the amounts drunk and the latencies. In contrast, artificial CSF containing glucose, urea, or artificial CSF alone were without effect. Plasma vasopressin concentration increased significantly in response to intraventricular NaCl and sucrose but was not affected by glucose, urea, or artificial CSF alone. These data are compatible with an osmoreceptor mechanism mediating drinking and vasopressin release.
Estimates of partial efficiency of young beef bulls.
Gain, feed consumption and feed efficiency records of 1,409 bulls that were individully fed at central test stations were analyzed. Feed for maintenance and feed for gain were estimated and used to study partial and gross efficiency and relative feed intake. Among the eight breed groups represented there was a range of 3.4% in the breed means for partial efficiency and of 1.6% in the means for gross efficiency. Relative feed consumption ranged from 2.82 to 3.10 times maintenance among the eight breed groups. Effects associated with location, year, breed and the interactions among these effects were significant for traits related to partial efficiency. If the bulls presented to these central tests are representative of their respective breeds, these results emphasize the importance of making comparisons within tests and finding more efficient cattle within the breed of choice.
Method of delivery and developmental outcome at five years of age.
A controlled follow-up study examined the impact of delivery method on developmental outcome of the child. The modes of delivery investigated were low forceps delivery (188 infants), midcavity forceps delivery (51 infants), forceps rotation with forceps delivery (57 infants), manual rotation with forceps delivery (67 infants), elective caesarean section (101 infants) and spontaneous delivery (control, 207 infants). Breech presentation (100 infants) was separately compared with the vertex presentation groups. Sample selection controlled for complications during pregnancy and low birthweight and was restricted to married English-speaking mothers. The children were assessed at the age of five years on verbal and non-verbal subtests of a standardized intelligence scale, tests of gross motor coordination, and auditory and visual tests. A full paediatric examination was also performed. Breech presentation children performed less well on tests of balance and fine motor coordination and on visual acuity and stereopsis testing than children who presented in the vertex position. No deleterious effect of delivery method was found. In the absence of other complicating events (like a poor antenatal history, prematurity, and a disorganized home environment) delivery complication constitutes an early risk factor which the growing child is able to overcome.
Size and shape of Kedah-Kelantan cows.
Body weight and nine body measurements were recorded on 79 mature Kedah-Kelantan cows at two locations. The Kedah-Kelantan is an indigenous cattle of Malaysia. A principal component analysis was used to study size and shape as indicated by the dependence structure among measurements. The total variation among measurements associated with the first principal component which was interpreted as a measure of general size was 40.8%. The second principal component contrasted cows tall at the withers, and deep at the chest with top line sloping downward and under line sloping upward from front to rear with those having less wither height and chest depth and straighter lines. This contrast accounted for 14.3% of the variation in body dimensions. The third principal component contrasted long, narrow, and deeper cows with a more compact type. This contrast accounted for 10.7% of the variation in body dimensions.
Immune response in progressor and regressor strains of chickens at specific intervals after a primary challenge with Rous sarcoma virus.
A progressor line and a regressor line of chickens were compared for development of immune response, after an initial inoculation of Rous sarcoma virus in the wing-web. Quantitative measures of immunity were determined for the two contrasting lines of chickens at specific intervals after the initial challenge. It was found that subsequent challenges, with either Rous sarcoma virus or tumor homogenate, in the opposite wing-web were met by an early immune response from the regressor line. This early response was absent in the progressor line. However, both lines showed a similar immune response after a time interval of 15 days from the initial challenge. The genes for regression exert this early immune response which is the key to spontaneous regression of Rous sarcomas.
Infants' response to facelike patterns: developmental changes between 10 and 15 weeks of age.
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