Showing papers by "University of North Carolina at Chapel Hill published in 1978"

Physical constraints on acoustic communication in the atmosphere: Implications for the evolution of animal vocalizations

Abstract: 1. Acoustic communication requires not only detection of the signal but also discrimination of differences among signals by the receiver. Attenuation and degradation of acoustic signals during transmission through the atmosphere will impose limits on acoustic communication. Attenuation of sound during atmospheric transmission results primarily from atmospheric absorption, ground attenuation, scattering of a sound beam, and deflection of sound by stratified media. For maximum range of detection, therefore, animals should favor optimal positions in their habitat and optimal weather conditions. Frequency-dependent attenuation seems not to differ consistently among major classes of terrestrial habitats, such as forests and fields. Increased scattering of higher frequencies from vegetation in forests is in part matched by scattering from micrometerological heterogeneities in the open. 2. In addition to frequency-dependent attenuation, two kinds of degradation during atmospheric transmission will limit a receiver's ability to resolve differences among acoustic signals: the accumulation of irregular amplitude fluctuations from nonstationary heterogeneities, often atmospheric turbulence, and reverberation. Both types of degradation affect temporal patterns of amplitude or intensity modulation more than patterns of frequency modulation. Both effects should increase with carrier frequency, as they depend on the relationship between wavelength and the dimensions of scattering heterogeneities. Irregular amplitude fluctuations are more severe in open habitats and primarily mask low frequencies of amplitude modulation; reverberations are more severe in forested habitats and primarily mask high frequencies of amplitude modulation and rapid, repetitive frequency modulation. This difference between forested and open habitats could explain previous reports that birds in the undergrowth of tropical forests avoid rapid frequency modulation in their long-range vocalizations. 3. Maximum range of detection is probably not the primary selection pressure on many animal vocalizations, even for territorial advertisement, except perhaps in tropical forests. Instead, acoustic signals might incorporate features that degrade predictably with range to permit a receiver to estimate the signaler's distance. Future investigations might explore the propagation of animal vocalizations in relation to the usual spacing of animals in their habitat. Features that encode different kinds of information, such as individual and species identity, might propagate to different distances. 4. Measurements of the transmission of sound in natural environments have often not controlled several important parameters. First, the effects of gound attenuation and scattering are not linear with range; consequently measurements of excess attenuation over different ranges in the same environment might differ. Second, the directionality of speakers and microphones will affect measurements of attenuation and reverberations in scattering environments. Third, as stationary waves shift with frequency, any single microphone placement will lie in a null for some frequencies and in a maximum for others.

Immunohistochemical localization of enkephalin in rat brain and spinal cord.

Abstract: The distribution of immunoreactive enkephalin in rat brain and spinal cord was studied by immunoperoxidase staining using antiserum to leucine-enkephalin ([Leu5]-enkephalin) or methionine-enkephalin ([Met5]-enkephalin). Immunoreactive staining for both enkephalins was similarly observed in nerve fibers, terminals and cell bodies in many regions of the central nervous system. Staining of perikarya was detected in hypophysectomized rats or colchicine pretretated rats. The regions of localization for enkephalin fibers and terminals include in the forebrain: lateral septum, central nucleus of the amygdala, area CA2 of the hippocampus, certain regions of the cortex, corpus striatum, bed nucleus of the stria terminalis, hypothalamus including median eminence, thalamus and subthalamus; in the midbrain: nucleus interpeduncularis, periaqueductal gray and reticular formation; in the hind brain: nucleus parabrachialis, locus ceruleus, nuclei raphes, nucleus cochlearis, nuclear tractus solitarii, nucleus spinalis nervi trigemini, motor nuclei of certain cranial nerves, nucleus commissuralis and formatio reticularis; and in the spinal cord the substantia gelatinosa. In contrast enkephalin cell bodies appear sparsely distributed in the telencephalon, diencephelon, mensencephalon and rhombencephalon. The results of the histochemical staining show that certain structures which positively stain for enkephalin closely correspond to the distribution of opiate receptors in the brain and thus support the concept that the endogenous opiate peptides are involved in the perception of pain and analgesia. The localization of enkephalin in the preoptic-hypothalamic region together with the presence of enkephalin perikarya in the paraventricular and supraoptic nuclei suggest a role of enkephalin in the regulation of neuroendocrine functions.

Occurrence of strange axiom a attractors near quasi periodic flows on tm, m is greater than or equal to 3

Abstract: It is shown that by a smallC 2 (resp.C ∞) perturbation of a quasiperiodic flow on the 3-torus (resp. them-torus,m>3), one can produce strange AxiomA attractors. Ancillary results and physical interpretation are also discussed.

The Relationship Among Heart Rate, Carotid dP/dt, and Blood Pressure in Humans as a Function of the Type of Stress

Abstract: In three experiments involving young adult males, beta-adrenergic influences on heart rate and carotid dP/dt were evaluated as a function of the degree of individual control over stressful events. Beta-adrenergic effects were more pronounced under conditions in which the subjects were either led to believe they had control or where some control was actually provided, i.e., a shock avoidance task. Beta-adrenergic influences were either minimal or rapidly dissipated under conditions where no control was possible, i.e., the cold pressor, a pornographic film, inescapable shocks, or conditions which provided ready mastery of the task. Where beta-adrenergic effects were maximal, systolic blood pressure was more appreciably elevated while diastolic blood pressure was less elevated than when beta-adrenergic effects were minimal. A pharmacological blocking agent (propranolol) was used in one experiment to specify the extent the various cardiovascular changes were influenced by beta-adrenergic activity. The results are discussed with respect to issues concerning stimulus parameters, blood pressure control mechanisms, individual differences in cardiovascular reactivity, and some methodological problems of the current study.

The medical interview satisfaction scale: Development of a scale to measure patient perceptions of physician behavior

Abstract: Patient satisfaction is a variable of increasing interest to researchers, clinicians, and medical educators. Of several studies reviewed, only a few have shown evidence of careful methodology. Most surveys have focused on general evaluations of doctors and/or health care services or of a particular facility. The present article reports the development of a scale to measure patient satisfaction with an encounter with a physician or other primary care provider. Methods of item generation and pretesting are detailed. The overall reliability of the scale (Cronbach's coefficient alpha) is 0.93. The distribution of satisfaction scores is broader than that reported for other scales and approaches the normal in shape. Clinical and research applications of the scale are suggested.

Modified t Tests and Confidence Intervals for Asymmetrical Populations

Abstract: This article considers a procedure that reduces the effect of population skewness on the distribution of the t variable so that tests about the mean can be more correctly computed. A modification of the t variable is obtained that is useful for distributions with skewness as severe as that of the exponential distribution. The procedure is generalized and applied to the jackknife t variable for a class of statistics with moments similar to those of the sample mean. Tests of the correlation coefficient obtained using this procedure are compared empirically with corresponding tests determined using Fisher's z transformation and the usual jackknife estimate.

Excitation of marginal and substantia gelatinosa neurons in the primate spinal cord: indications of their place in dorsal horn functional organization.

Abstract: Elecrophysiological recordings were made from superficial parts of the spinal dorsal horn in monkeys, using dye-filled micropipette electrodes to permit iontophoretic marking of the recording sites for subsequent histological recovery. Focal field potentials and unitary activity evoked by dorsal root volleys including slowly-conducting components (both myelinated and unmyelinated) were found in the posteromarginal zone and the substantia gelatinosa (SG). Unitary potentials identified as being of the type recorded from cellular regions wee separated into categories according to which groups of slowly-conducting fibers and which kinds of cutaneous stimulation evoked the discharge. Recording locations for units exicted by volleys in myelinated fibers conducting under 35 m/sec, by the types of skin stimulation activating either highthreshold mechanoreceptors (nociceptos) or cooling thermoreceptors, and giving no evidence of suprathreshold C-fiber excitation were centered on the posteromarginal zone. In conrast, recording loci for units exhibiting a strong C-fiber excitation and responses to cutaneous stimulation known to effectively excite C-fiber polymodal nociceptors or C-mechanoreceptors were centered in the SG. There appeared varying degrees of convergence of primary afferent input to the neuronal units, although most showed substantial specificity in their afferent excitation. On the bases of these esults and consideration of existing morphological daa, it is proposed that the marginal zone is a major synaptic termination region for the affeent fibers from high-threshold mechanoreceptors, cooling thermoreceptors, and perhaps otehr receptors with fine myelinated peripheral fibers. The SG, on the other hand, is suggested to be the terminal region for all types of unmyelinated primary afferent sensory neurons, and to have the complex role of integrating and distributing this input.

Kinematical conditions in the construction of spacetime

Abstract: We adopt the point of view that a solution of Einstein's equations is an evolution of given initial Cauchy data. Implementing the evolution equations necessarily requires a determination, not directly dictated by the field equations, of the kinematics of the observers in terms of which the evolution is represented. In this paper we study the observers' kinematics (velocities and accelerations) in terms of the geometry of their congruences of world lines relative to families of time slicings of spacetime, which contrasts with the more usual approach of imposing particular "gauge" or "coordinate conditions." The types of conditions we suggest are adapted to the exact Einstein equations for general strong-field, dynamic spacetimes that have to be calculated numerically. Typically, the equations are three-dimensionally covariant, elliptic, and linear in the kinematical functions (the lapse function and shift vector) that they determine. The gravitational field enters in nonlinear form through the presence of curvature in the equations. We present a flat-space model of such elliptic equations (e.g. for maximal slicing) which suggests that this curvature leads to an exponential decrease in the proper time between time slices at late times. We show how the use of maximal slicing with minimal-distortion observers generalizes the notion of a stationary rest frame to dynamical asymptotically flat spacetimes. In cosmological spacetimes the use of minimum-distortion observers is shown to differentiate between those universes which contain only kinematic time dependence (e.g. open Kasner universe) and those in which dynamical degrees of freedom are present (e.g. mixmaster universe). We examine many examples and construct new coordinate systems in both asymptotically flat and cosmological solutions to illustrate these properties.

X-ray photoelectron spectroscopy of alkylaminesilanes bound to metal oxide electrodes

Abstract: Abstract : ESCA results are presented for SnO2, RuO2, TiO2, and Pt/PtO oxide electrodes silanized with trialkoxyalkylaminesilanes. Observations include effects of reaction conditions, assay of the fraction of amine-like surface nitrogen, assay of N/Si surface atom ratios, O 1s spectra, and fluoride dopant depth profile in SnO2. The silanized surfaces are amine-like but also exhibit other chemical features. The implications of various alkylaminesilane surface structures on electrochemical applications are discussed. (Author)

Purification and Localization of Acidic Epididymal Glycoprotein (AEG): A Sperm Coating Protein Secreted by the Rat Epididymis

Abstract: A protein designated acidic epididymal glycoprotein (AEG) was purified from rat epididymis using ion exchange chromatography on DEAE-Sephadex, gel filtration in Sephadex G-75 and affinity chromatography on Concanavalin-A Sepharose. AEG is a major secretory product of the epididymis making up 2–3 per cent of total soluble protein. Antibody to AEG was raised in rabbits and purified by affinity chromatography on AEG-Sepharose. Quantitation of AEG in cytosol using “rocket” immunoelectrophoresis showed AEG to increase in epididymal segments from caput to cauda. Ligation of the midcorpus decreased AEG in the cauda. Localization of AEG using an immunoperoxidase method revealed that it is secreted largely by the epithelium of caput and corpus beginning with the region distal to the initial segment. It appears to be secreted by a specific cell type, probably the so-called “principal” cell. Specific staining of AEG was also noted in “clear” cells in the cauda. Spermatozoa become coated with AEG as they leave the initial segment and remain so during passage through the cauda.

Antecedents of child abuse and neglect in premature infants: a prospective study in a newborn intensive care unit

Abstract: Families of premature and ill newborns admitted to a regional newborn intensive care unit were studied prospectively to assess the incidence of reported child abuse and neglect. Of the 255 infants discharged to their parents, ten were subseqtiently reported as victims of maltreatment during the first year of life. The high incidence of maltreatment (3.9%) in these Prelnatttre and ill newborns supports the findings of retrospective studies that there is an increased risk of maltreatment in these special infants. Thirteen family psychosocial characteristics, assessed by admission interview, showed significant association with later maltreatment. These family characteristics included social isolation, a family history of child abuse and neglect, serious marital problems, inadequate child care arrangements, apathetic and dependent personality styles, and inadequate child spacing. Maltreated infants were less mature at birth and had more congenital defects than their nursery mates. There was also less family-infant contact during the prolonged nursery hospitalization in families in which maltreatment eventually occurred.

Laminar origins of spinothalamic projections in the cat as determined by the retrograde transport of horseradish peroxidase

Abstract: The method of retrograde axonal transport of horseradish peroxidase (HRP) was used to identify the locations of cells of origin of the spinothalamic tract in the cat. Injections of from 0.2–3.0 μl of 30% HRP were made unilaterally in various regions of the somatosensory thalamus. Massive injections of the caudal thalamus in several cats showed the spinothalamic cells of origin to be located mainly in laminae I, VII and VIII in the lumbar enlargement, and in laminae I, V and VII–VIII in the cervical enlargement. Small injections of HRP were made into the three major spinothalamic terminal zones in the thalamus, to determine the laminar origin(s) of the spinal projections to each zone. Neurons in lamina I in both cervical and lumbar enlargements were found to project almost exclusively to the rostral VB-caudal VL border zone. A small number of neurons in laminae VII and VIII also project there but a larger number project to the intralaminar region. Neurons projecting to the PO regions were located mainly in laminae IV and V. This anatomical segregation of thalamic afferents probably reflects a functional segregation of input, since the functional properties of spinal neurons vary according to their laminar location. Comparison of these data with the differential projection spinothalamic neurons in the rat and monkey indicate that it is unlikely that the proposed “paleo-” and “neospinothalamic” systems would arise from anatomically separate groups of spinal neurons.

Acoustic features and auditory perceptions of the cries of newborns with prenatal and perinatal complications.

Abstract: This article describes 2 experiments which examine the relation between neonatal cry features and obstetric histories. Experiment 1 shows that 24 clinically healthy, normal newborns who may be at risk due to a high number of prenatal and perinatal complications can be distinguished from 24 low-complications infants by harmonic and durational features of the cry. High-complications infants required more stimulation to elicit the cry, had a longer latency to cry onset, a shorter first cry expiration, a higher cry pitch, and cried less in total time than low-complications infants. In experiment 2, naive adults rated the high-complications infant cries as more aversive, grating sick, urgent, distressing, piercing, discomforting, and arousing than low-complications infant crues. Factor analyses showed that although the low-complications infant cries were described along one dimension of discomfort, a second factor emerged conveying the "sick" nature of the sound of the cry of the high-complications infants. It was suggested that certain cry features may reflect the risk status of the infant.

Forest vegetation of the colorado front range: patterns of species diversity*

Abstract: Plant species diversity patterns of the Rocky Mountain forests were found to be at variance with patterns reported from other regions. The most centrally located forests in terms of elevation, site moisture and successional status were found to have the lowest diversity. In contrast, the peripheral and environmentally more severe sites were found to have relatively high diversity. In particular, the forest-grassland transition and the low elevation riparian forests have species diversity values as high as any yet reported from western North America. When diversity was examined in terms of variation across elevation or moisture gradients, varying results were obtained due to the interaction of these factors. The failure of previous studies to converge on generalizations about plant diversity reflects, in part, the failure of most investigators to view diversity in a regional context of variation across several interacting gradients. Diversity was seen to vary inversely with the degree of development of the forest canopy. The interaction of different components of the forest community is one reason for the failure of general patterns of plant species diversity to emerge from previous studies. A potentially rich herb community can be greatly suppressed by a single species tree stratum. Among the most successful work to date on species diversity is that on birds, a distinct albeit large and functional group. It is unlikely that similar success could have been achieved through work on all animal species simultaneously. This suggests the need to examine plant species diversity, not in terms of total diversity, but in terms of component functional groups, perhaps guilds, growing under similar microclimatic conditions and subject to similar competitive pressures.

Cell death of motoneurons in the chick embryo spinal cord. III. The differentiation of motoneurons prior to their induced degeneration following limb‐bud removal

Abstract: The differentiation of motoneurons following early limb-bud ablation was studied in chick embryos from four days to hatching. Following the removal of the normal targets of these cells about 90% of the neurons in the lateral motor column (LMC) of segments 23–29 (lumbar) were found to disappear. By counting degenerating cells it was shown that virtually all of the cell loss could be accounted for by cell death, rather than impaired proliferation or enhanced migration away from the LMC. Quantitative comparisons of cell death between the peripherally deprived and the control, non-deprived side demonstrated that limb-bud removal not only enhanced the 50% natural cell death known to occur in this system, but also greatly accelerated the whole process. By stage 30 (6.5-7 days) 75% of the final cell loss had occurred on the deprived side, whereas only 40% of the final cell loss had occurred on the control side. In both cases, however, cell death was confined to the period of limb innervation. Axon counts of the peripherally deprived ventral root showed that all the deprived neurons initially had sent an axon out of the spinal cord. Most of these, however, became caught in a neuroma before reaching the site of limb attachment. Though no synapses were found in the neuroma the axons were shown to be able to transport HRP back to the spinal cord. Before they began to degenerate, the deprived LMC motoneurons developed dendritic processes and these were able to form synapses with axons in the prospective lateral white matter. In early stages, frequent axo-glial “synapses” were observed in the prospective lateral white matter of both deprived and control sides of the spinal cord. Since by stage 36 (day 10) these had virtually all disappeared, it was suggested that synapse formation in this region of the spinal cord may initially be under few constraints. In late stages (i.e., after day 8) it was noted that there were frequently signs of axonal degeneration in the lateral white matter on both sides of the spinal cord, suggesting a retrograde transneuronal degeneration initiated by the earlier cell death of motoneurons. Electron microscopic examination of the deprived LMC cells at different stages prior to degeneration failed to uncover any obvious differences between them and control cells on the non-deprived side of the spinal cord. By histochemical and neurochemical methods the cholinergic enzymes acetylcholinesterase and choline acetyltransferase were found to develop normally up until the onset of frank degeneration in the deprived motoneurons, on day 5 or 6. After this the enzymes decreased at a rate comparableto the morphological loss of motoneurons by cell death. On the basis of these various lines of evidence, it is argued that all the motoneurons in the LMC have a remarkable intrinsic capacity to initiate differentiation and that neurons experimentallydeprived of their normal target are no different in this respect.

Prevalence of self-injurious behaviors in a large state facility for the retarded: a three-year follow-up study.

Abstract: A combined informant questionnaire and interview survey of self-injurious behavior (SIB) at a large state facility for the retarded was conducted independently three times over a 3-year period. Prevalence consistently was about 10% of the population. SIB cases tended to be younger and institutionalized longer than the rest of the population. Severe cases had a longer history of chronic SIB. SIB cases had more seizure disorders, severe language handicaps, visual impairments, and severe or profound retardation than the rest of the population. They appeared to fulfill most of the Rutter (1966) criteria for autism. But unlike the severely autistic, there was little relation of sex to incidence of SIB. Over 90% of SIB cases changed status over 3 years, suggesting that SIB was amenable to behavior modification in most cases (94%). Psychotropic behavior control medications helped in some intervention programs (52%). SIB remitted spontaneously in 27% of SIB cases where there had been no behavioral or drug intervention.

The principal components of mixed measurement level multivariate data: An alternating least squares method with optimal scaling features

Abstract: A method is discussed which extends principal components analysis to the situation where the variables may be measured at a variety of scale levels (nominal, ordinal or interval), and where they may be either continuous or discrete. There are no restrictions on the mix of measurement characteristics and there may be any pattern of missing observations. The method scales the observations on each variable within the restrictions imposed by the variable's measurement characteristics, so that the deviation from the principal components model for a specified number of components is minimized in the least squares sense. An alternating least squares algorithm is discussed. An illustrative example is given.

Grouping Observations in Digital Simulation

Abstract: This paper presents a method for deriving a confidence interval for a population mean from the output of a simulation run. The method groups the observations on a run into batches and uses these batches as the basic data for analysis. The technique is not new. What is new is the procedure for determining how to group the observations into batches that satisfy certain assumptions necessary for the technique to work correctly. It is inexpensive and requires a moderate knowledge of statistics. The results of testing the method on a single server queuing model with Poisson distributed arrivals of exponentially distributed service times M/M/1, indicate that the proposed technique performs as theory suggests for moderate activity levels. However, for higher activity levels performance is below theoretical expectation for small sample sizes n. As n increases, performance converges to expectation. Moreover, two calculations of the sample sizes needed to obtain results with moderate accuracy indicate that these sample sizes are in a range where the procedure is expected to perform with small error.

Gene dosage compensation and the evolution of sex chromosomes.

Abstract: Dosage compensation is a mechanism by means of which the activity of X-linked or Z-linked genes is made equal in the two sexes of organisms with an XX compared to XY or ZZ compared to ZW basis of sex determination. In mammals, compensation is achieved by the inactivation of one X chromosome in somatic cells of females. In Drosophila, compensation does not involve inactivation. The two X chromosomes in females as well as the single X in males are regulated, and individual genes are thought to respond independently to the regulatory mechanism. It is proposed that in both groups of organisms the evolution of heteromorphic sex chromosomes was gradual and occurred as the direct result of the evolution of dosage compensation rather than the reverse.

Diarylamidine derivatives with one or both of the aryl moieties consisting of an indole or indole-like ring. Inhibitors of arginine-specific esteroproteases

Abstract: A series of 62 diarylamidine derivatives was evaluated for their antiproteolytic activity. In all but two of the compounds one or both of the amidino-substituted aryl moieties was either an indole or an indole-like ring. The latter included indene, benzimidazole, benzofuran, benzol[beta]thiophene, and several other related nitrogen-containing heterocycles. Several of the compounds exhibited considerable inhibitory potency against thrombin, trypsin, and pancreatic kallikrein. An outstanding inhibitor of trypsin was found in bis(5-amidino-2-benzimidazolyl)methane (compound 42) with a Ki value of 1.7 X 10(-8) M(pH. 8.1, 37 degrees C). Another derivative, 1,2-di(4-amidino-2-benzofuranyl)ethane (compound 21), proved to be a highly effective inhibitor of the overall blood clotting process. From a general structure-activity standpoint these compounds demonstrate that minor structural variations of low-molecular-weight inhibitors can result in significant changes in specificity and potency with regard to antiproteolytic activity.

Hand structure and function in an industrial setting.

Abstract: The influence of patterns of usage on the structure and function of the hands was formally tested. Three groups of female textile workers, each employed in a distinct and defined, atraumatic, repetitive, stereotyped manual task for at least 20 years, were identified in a single rural mill. Replicate data were obtained for the following measures of structure and function: range of motion, a score for the degree of radiographic degenerative changes at each hand joint, malalignment at digital joints determined radiographically, and a quantitative measure of osteophyte formation. Significant and consistent differences in the right hand when compared to the left were detected. Furthermore, highly significant task-related differences were demonstrated. These task-related differences in the structure and function of the hands were consistent with the pattern of usage. Therefore these three patterns of usage influence hand structure and function in the population studied.

Verbal Response Modes and Dimensions of Interpersonal Roles: A Method of Discourse Analysis.

Abstract: Utterances in dyadic communication can be described as concerning the speaker's or the other's experience, using the speaker's or the other's frame of reference, and being focused on the speaker or the other (where "focus" means presuming or not presuming knowledge of the other). The intersection of these three dichotomous principles of classificatio n defines eight familiar verbal response modes: disclosure, question, edification, acknowledgment, advisement, interpretation, confirmation, and reflection. Each mode has a distinctive grammatical form as well as a distinctive interpersonal intent, so the form and the intent of an utterance can be coded separately. The modes can be used to define three conceptually orthogonal dimensions of interpersonal roles, tentatively labeled attentiveness, acquiescence, and presumptuousness. The system of verbal response modes and role dimensions is similar in purpose to Bales's interaction process analysis but has certain methodological and conceptual advantages. A verbal response mode is a category of language behavior that implies a particular interpersonal intent or microrelation ship between communicator and recipient. For example, a question asks for information or advice from the recipient; a self-disclosur e reveals feelings, attitudes, or intentions to the recipient; advice suggests that certain things be done by the recipient. A summary »of the modes used during an interpersonal encounter describes the relationship that existed during the encounter. For example, one dyadic interaction might consist mostly of self-disclosures by both members, whereas another might consist mostly of questions by one member and advice by the other. Verbal response modes describe and quantify the clear differences between the dyad members' relationships in these two interactions.