Showing papers by "University of Oregon published in 1973"
TL;DR: The spectrum of the Fokker-Planck operator for weakly coupled gases is considered in this paper, where the operator is decomposed into operators acting on functions whose angular dependence is given by spherical harmonics.
Abstract: The spectrum of the Fokker-Planck operator for weakly coupled gases is considered. The operator is decomposed into operators acting on functions whose angular dependence is given by spherical harmonics. It is shown that the operator corresponding to l = 0 has zero for a point eigenvalue (the eigenfunction is the Maxwell distribution). There are no other point eigenvalues and the continuous spectrum of all of the operators is the entire negative real axis. Some consequences are briefly discussed.
1,270 citations
TL;DR: The properties of four igneous rocks (a tholeiitic and an alkali-olivine basalt, an andesite, and a rhyolite) and a synthetic lunar sample have been determined at atmospheric pressure over a range of temperatures including their melting interval as discussed by the authors.
Abstract: The properties of four igneous rocks (a tholeiitic and an alkali-olivine basalt, an andesite, and a rhyolite) and a synthetic lunar sample have been determined at atmospheric pressure over a range of temperatures including their melting interval. Viscosity, density, electrical and thermal conductivity, ultrasonic wave velocities, surface tension, and vesiculation rates were measured directly; these data have been used to calculate values for thermal expansion, compressibility, ultrasonic wave attenuation, and activation-energy coefficients.
953 citations
TL;DR: Many combinatorial enumeration problems may be expressed in terms of the numbers Pc (“m”).
Abstract: Given a positiver integer m and an ordered k-tuple c = (c1, ··· , ck) of not necessarily distinct positive integers, then any ordered k-tuple s = (s1, ··· , sk) of nonnegative integers such that m = ∑ki-1sici is said to be a partition of m restricted to c. Let Pc(m) denote the number of distinct partitions of m restricted to c. The subroutine COUNT, when given a k-tuple c and an integer n, computes an array of the values of Pc(m) for m = 1 to n. Many combinatorial enumeration problems may be expressed in terms of the numbers Pc(m). We mention two below.
647 citations
515 citations
421 citations
TL;DR: In a recognition memory experiment, the time allowed for retrieval was controlled by using the offset of the probe as a signal to terminate retrieval and respond, indicating that this procedure effectively eliminated fast-guess strategies.
Abstract: In a recognition memory experiment, the time allowed for retrieval was controlled by using the offset of the probe as a signal to terminate retrieval and respond. The response latencies measured in the experiment indicate that this procedure effectively eliminated fast-guess strategies. The recognition signal-to-noise ratio, d', grows at a negatively accelerated rate as the allowed retrieval time is increased from 0.5 second to 1 and 2 seconds.
343 citations
TL;DR: The secondary task technique uses the interference between a primary task and a secondary task to assess the extent to which the primary task makes processing demands on the central limited system.
Abstract: Man possesses a central system of limited capacity. Theorists at first described this system as a single limited capacity channel Two current theoretical alternatives to single-channel theory are (1) the undifferentiated capacity hypothesis that man possesses a pool of capacity units so that interference occurs oniy if the total number of capacity units that mental operations demand exceeds the system limit and (2) the hypothesis that some, but not all, mental operations require space in a limited capacity central mechanism and that any operation that requires space will interfere with any other operation that also demands space. Time on task fails as a sensitive measure of capacity demands because some task components require time but not full processing capacity. The secondary task technique uses the interference between a primary task and a secondary task to assess the extent to which the primary task makes processing demands on the central limited system. Processing demands have been measured for five categories of mental operation: (1) encoding, (2) multiple input, (3) rehearsal, (4) transformation, and (5) responding.
300 citations
TL;DR: The behavioral patterns of reef fishes make clear the relationships between underwater light and the visual pigments, and crepuscular predators obtain a visual advantage by having moderate numbers of very large cones, which provide adequate sensitivity and sufficient resolution for motion detection.
273 citations
TL;DR: A preparation of the desert locust has been developed, in which it was possible to work with identified neurons while still allowing some behavior, and it is inferred that impulses are initiated in a zone tentatively identified with the region of emergence of the motor axon from the neuropil.
Abstract: A preparation of the desert locust, Schistocera gregaria, has been developed, in which it was possible to work with identified neurons while still allowing some behavior. A total of 26 motorneurons to the hind leg were studied singly, and in various pairs, both by direct stimulation, and by recording during spontaneous activity and various reflex actions. Motorneurons were identified by passing current into their somata and correlating the evoked somata spikes with extracellularly or intracellularly recorded events in the muscles. Tension of the muscle was also recorded and motor axons were stimulated to evoke antidromic spikes in the somata. Both epsp's and ipsp's can be seen clearly in recordings from the somata; spikes appear as electrotonically conducted remnants only. Somata exhibited little or no electrogenesis. It is inferred that impulses are initiated in a zone tentatively identified with the region of emergence of the motor axon from the neuropil. Integration occurs in the neuropilar segment, with the soma serving as a parallel RC element. Data was obtained on the central mechanisms of coordination of synergistic and antagonistic motorneurons and on the modes of excitation of slow and fast neurons to the same muscles.
248 citations
TL;DR: The basic microvascular anatomy of the human dura is described, which gives rise to two outer anastomotic sets of vessels that descend to supply a rich capillary network located near the arachnoid.
Abstract: The basic microvascular anatomy of the human dura is described. The named dural arteries give rise to two outer anastomotic sets of vessels. From the outer arteries, penetrating vessels descend to supply a rich capillary network located near the arachnoid. Arteriovenous shunts are present in the midportion of the dura, which may function to bypass the capillary network.
TL;DR: In this article, the authors examined the relationship between a child's auditory and verbal skills and the noisiness of his home and found that children living on the lower floors of 32-story buildings showed greater impairment of auditory discrimination and reading achievement than children living in higher-floor apartments.
TL;DR: It is shown that alertness does not affect the buildup of information within the memory system but only the rate at which a later system responds to that information, and in standard reaction-time tasks, increased alertness produces a reduction in reaction ’time but no decrease in errors.
Abstract: In a previous paper, it was argued that alertness, selectivity (set), and processing capacity (consciousness) could be identified and studied as separate components of attention. The current paper develops this theme by showing that alertness does not affect the buildup of information within the memory system but only the rate at which a later system responds to that information. Thus, in standard reaction-time tasks, increased alertness produces a reduction in reaction ’time but no decrease in errors. In contrast, providing a model of the signal the S is to process improved both speed and accuracy. The,. presence of a model of what the S is to process varies the vertex neural response to that specific signal as compared to a mismatching signal in the first 200–300 msec after its presentation. Three accounts of this effect are: speeded processing of a matching stimulus, habituation of the electrical response to a matching stimulus, and prolonged or enhanced processing of a mismatch. Evidence favors the first of these explanations, but the other two cannot be dismissed as possible contributors to this effect.
TL;DR: The model explains europium anomalies in plagioclase synthesized under controlled laboratory conditions as well as the variations of the anomaly observed in natural terrestrial and extraterrestrial igneous rocks.
Abstract: The partition of europium between plagioclase feldspar and magmatic liquid is considered in terms of the distribution coefficients for divalent and trivalent europium. A model equation is derived giving the europium anomaly in plagioclase as a function of temperature and oxygen fugacity. The model explains europium anomalies in plagioclase synthesized under controlled laboratory conditions as well as the variations of the anomaly observed in natural terrestrial and extraterrestrial igneous rocks.
TL;DR: A retrospective examination was made of a total of 48 patients with infected prosthetic cardiac valves implanted in 1,236 patients during 1960-1972 to determine the factors which aided or decreased patient survival and to develop a program of treatment with antimicrobial agents.
Abstract: A retrospective examination was made of a total of 48 patients with infected prosthetic cardiac valves implanted in 1,236 patients during 1960-1972. Survival rate of the valvular infections was 40%. The purpose of the study was to determine the factors which aided or decreased patient survival and to develop a program of treatment with antimicrobial agents. Numerous antimicrobics and a variety of dosage schedules were used. Of 19 surviving patients, medical treatment alone was effective in 14, despite the continued presence of a valvular prosthesis. Reoperation was successful in five of nine patients. Lifelong chemoprophylactic or suppressive therapy was shown to be unnecessary to prevent relapse in 12 survivors. Prompt surgical replacement is indicated if antimicrobial therapy fails to eradicate infection of a prosthetic valve. A more systematic approach to antimicrobial therapy should improve survival of medically treated infections. Recommendations are made for prevention and treatment of prosthetic va...
TL;DR: The pH-dependent transitions and the thermal unfolding of defatted human serum albumin in 0.2 m KCl as followed by polarimetry at 233 nm are found to be independent processes that impart the ability to unfold simultaneously, but more or less independently.
TL;DR: It is found that specific neurons play clearly defined and invariant roles in control of escape-swimming and that the neuronal circuitry underlying the coordination of the sequence is the same in different individuals of the species.
Abstract: We have investigated the roles played by numerous identified brain cells in initiating and controlling the coordinated sequence of movements of an instinctive escape-swimming sequence in an intact animal preparation of the nudibranch mollusc Tritonia diomedia. Intracellular electrical activity in different neurons has been correlated with the various phases of the behavior. We recognized four major stages in the response: (1) reflex local withdrawal; (2) preparation for swimming; (3) swimming; and (4) termination. We have located and studied brain cells whose activity is associated with the following aspects of swimming: withdrawal; elongation; triggering behavior; dorsal flexion; ventral flexion; and neurons which excite both dorsal and ventral flexor neurons simulataneously.
We find that specific neurons play clearly defined and invariant roles in control of escape-swimming and that the neuronal circuitry underlying the coordination of the sequence is the same in different individuals of the species. Details of the neuronal circuitry and a number of the general functional attributes of interacting cell groups have been determined directly or inferred from observations of cell to cell interactions. A preliminary model of the neuronal apparatus which controls this behavior is discussed. The principal findings are: (1) a discrete group of electrically coupled neurons determines, by its output, whether or not escapeswimming will be executed; (2) the neuronal elements responsible for execution of the swimming stages of the sequence are maintained in an excited state for the required period, in part by a regenerative feedback system; (3) alternating bursts of impulses in functional antagonists are co-ordinated in part by reciprocal inhibition between them; and (4) termination of the sequence occurs abruptly at a particular phase in the swimming cycle and appears to be an active neural process, rather than a simple running-down.
TL;DR: The frequencies and intensities of the laser Raman spectra of poly‐L‐lysine (PLL) have been observed in the following studies: the thermally induced α‐to‐β transition which occurs with increasing temperature at high pH, and the ionized form to α transition at 10°C by increasing pH.
Abstract: The frequencies and intensities of the laser Raman spectra of poly-L-lysine (PLL) have been observed in the following studies: (1) the thermally induced α-to-β transition which occurs with increasing temperature at high pH; (2) the ionized form to α transition at 10°C by increasing pH; and (3) the ionized form to α transition by ionic strength at low pH.
The frequency-dependent bands which have been observed are the amide I (in H2O), amide I′ (in D2O), amide III, and C–C stretch. It has been found possible to assign an unique set of frequencies and intensities to each conformation of PLL of α, β, and ionized form. In this way the nature of the conformations intermediate in the transitions can be determined. The frequencies of the amide III and amide III′ are very weak in the α-helix and somewhat higher than usual in the β form. Hence it appears the amide III and amide III′ bands may differ from one type of polypeptide to another with the same backbone conformation.
TL;DR: This chapter discusses that, on the basis of the observations, one can say with some certainty that the ultimate recovery of progeny in drosophila probably represents the aggregation of a great number of largely uncontrollable physiological events.
Abstract: Publisher Summary This chapter presents that from the beginning of the development of sperm in the testis of the male up to and including the ultimate recovery of that sperm in the form of progeny, variability is the only consistent feature in all aspects of the reproductive biology of drosophila This variability exists at virtually all levels of the reproductive systems in both the male and the female and, not surprisingly, is a reflection of a multitude of complex and, seemingly, hopelessly intertwined interactions between the genetic constitution of the organism and its particular environment This chapter discusses that, on the basis of the observations, one can say with some certainty that the ultimate recovery of progeny in drosophila probably represents the aggregation of a great number of largely uncontrollable physiological events The chapter also reviews that that in designing future experiments in drosophila, those whose interpretation depends on the control of this variability in reproduction
TL;DR: There is no relation between location in the ganglion and the muscle innervated, but locomotor motorneurons are clustered togethers in anterior, ventral, and lateral pockets.
Abstract: Somata of 26 of the motorneurons situated on the right side of the metathoracis ganglion of the locust S. gregaria were identified by correlating their electrical activity with extracellularly or intracellularly recorded muscle potentials evoked either reflexly or by direct elctrical stimulation of the somata through the recording microelectrode. The neurons identified included most of those innervating the major leg muscles. Each neuron occupies a relatively fixed site on the ventral surface of the ganglion. The identified neurons were filled with procion yellow, the ganglia fixed and photographed as whole mounts, and then serially sectioned to determine the three dimensional topography of the major dendrites and the pathway of the axons through the neuropil. The topographical features of individual motorneurons were sufficiently characteristic to permit identification, Nevertheless, it was not found possible to classify the neurons on the basis of branching pattern. There is no relation between location in the ganglion and the muscle innervated, but locomotor motorneurons are clustered togethers in anterior, ventral, and lateral pockets.
TL;DR: The special case of laughter to discrepant or incongruous stimulation is described in detail, and it is suggested that laughter serves the function of signaling to a caretaker that a given stimulus is within the child's tolerable limits of arousal.
Abstract: Research studies of laughter in children are reviewed, and a model describing eliciting conditions for laughter and related behavior is described. Following Spencer (1860), Berlyne (I960), and others, it is proposed that laughter occurs after conditions of heightened tension or arousal when at the same time there is a judgment that the situation is safe or inconsequential. The special case of laughter to discrepant or incongruous stimulation is described in detail, and it is suggested that laughter serves the function of signaling to a caretaker that a given stimulus is within the child's tolerable limits of arousal.
TL;DR: This article evaluated a set of previously assembled and proven behavior modification techniques and compared the effects of these techniques to a placebo treatment emphasizing status attention and expectancy features inherent in the procedures and found that the treatment condition milieu was characterized by a significantly higher rate of approval than the placebo condition.
TL;DR: His bundle electrograms (H) were recorded in 61 patients without evidence of conduction disease on the surface electrocardiogram, in order to establish the normal range ofConduction intervals, which will be of use in assessing patients with suspected cardiac conduction Disease.
TL;DR: An account of the brain (paired cerebral, pleural, and pedal ganglia) of the nudibranch mollusc Tritonia diomedia is presented and a standardized system of abbreviation and notation for the central ganglia, nerve trunks, and gaint somata is proposed.
Abstract: An account is presented of the brain (paired cerebral, pleural, and pedal ganglia) of the nudibranch mollusc Tritonia diomedia. The major efferent nerve fibers are related to their nerve cell bodies and their functional roles identified as far as possible. The channels of sesory input relating to some of these neurons are given so as to provide an overall view of the organization of the brain.
A standardized system of abbreviation and notation for the central ganglia, nerve trunks, and gaint somata is proposed. The system of references is intended to provide a guide to the location in the ganglia of many of the smaller neurons of which the functional attributes are known, but which cannot be consistently recognized on visual criteria alone. A system of rectangular coordinates is proposed which is applied to the natural outline of the ganglia. In addition, a system of cell notation is described which is independent of the co-ordinates used to define the position of the cell on the grid. Cell which by reason of their size, pigmentation, characteristic location and physiological attributes are consistently recognizable from animal to animal are numbered. Two principles were followed in numbering cells; (i) the series begins at unity in each ganglion; (ii) cell homologues in opposite ganglia are given the same number, but distinguished by prefixing the abbreviation for the ganglion in which they occur. It is considered that the system will facilitate the exchange of information between workers on the same species, and also benefit the comparison of neural organization of behavior in closely related forms.
The brain is organized in an almost exactly bilaterally symmetrical manner. There are a few bilateral neural pathways, but the major functional routes are ipsilateral. A few motorneurons, which are uniquely identifiable anatomically, cause unique, discrete movements. Others are in small groups sharing overlapping or similar functions.
TL;DR: A spectral analysis reveals a remarkable similarity between the phospholipid bilayer regions in the cytochrome oxidase model membranes and bilayers formed by the isolated lipids, whereas the boundary lipid component has no counterpart in lipid bilayers.
01 Jun 1973
TL;DR: In this article, it was shown that in many cases the apparent zeta potential of cells and charged particles is raised when dextran or other neutral polymers are included in the suspending medium.
Abstract: Electrokinetic measurements have shown that in many cases the apparent zeta potential of cells and charged particles is raised when dextran or other neutral polymers are included in the suspending medium. A consideration of artifacts which could be introduced by the presence of polymer suggests that the experimental results reflect a true increase in the electrokinetic potential. The dependence of the relative zeta potential increase on the type of cell or particle used implicates polymer adsorption in the explanation of the effect. Previously suggested explanations involving a rearrangement of the surface region to expose additional charge groups or a dielectric constant change in the double layer region are shown not to apply in general. Furthermore, although dextran increases the solubility of NaCl in aqueous solution, electrophoretic evidence strongly suggests that ion binding to an adsorbed polymer layer is not responsible for the effect. No satisfactory explanation for the zeta potential increase appears to have been offered.
TL;DR: Face grooming sequences that involve coordination of the shoulders, tongue, and eyes develop remarkably normally in inbred mice with one or both forelimbs amputated from birth indicates endogenous control with a strong genetic component.
Abstract: Face grooming sequences that involve coordination of the shoulders, tongue, and eyes develop remarkably normally in inbred mice with one or both forelimbs amputated from birth. This indicates endogenous control with a strong genetic component. Evidence for the maturational expression of "sensory expectations" was also obtained.
TL;DR: Data on this and other patients with ataxia-telangiectasia suggest that mutant clones of lymphocytes with specific translocations sometimes arise and proliferate, perhaps representing a step toward the lymphoid neoplasia to which such patients are predisposed.
Abstract: A clone of lymphocytes marked by a chromosome translocation was followed in a patient with ataxia-telangiectasia over a period of 52 months until death at the age of 23. The translocation involved both chromosomes 14. Initially, the patient had a small proportion (1 to 2 per cent) of lymphocytes with the translocation, markedly reduced response to phytohemagglutinin and increased chromosome breakage. Later studies showed increasing proportions (25 to 46 per cent) of translocation lymphocytes, more vigorous response to phytohemagglutinin and less chromosome breakage. The translocation lymphocytes gradually became the main (56 to 78 per cent) population. Data on this and other patients with ataxia-telangiectasia suggest that mutant clones of lymphocytes with specific translocations sometimes arise and proliferate, perhaps representing a step toward the lymphoid neoplasia to which such patients are predisposed. Lymphocyte clones for ataxia-telangiectasia may thus be analogous to chronic-myelogenous-...
TL;DR: In this paper, the authors studied the discriminability of a target when presented in briefly flashed displays of upright T's and L's and found that an L and a tilted T were equal in discriminative ability when attention was focused or concentrated on one display position.
Abstract: Two experiments studied the peripheral discriminability of a target differing in its line slope (a tilted T) and in its line arrangement (an L) when presented in briefly flashed displays of upright Ts. The results showed that: (a) an L and a tilted T were equal in discriminability when attention was focused or concentrated on one display position, (b) the discriminability of an L decreased while the discriminability of a tilted T was not statistically significantly affected as the number of display positions that attention needed to be paid to increased, and (c) the reaction time to find a disparate tilted T was less than that to find a disparate L. The results are interpreted as supporting the hypothesis that, under distributed attention in peripheral vision, the visual system is more sensitive to differences in line slope than to differences in line arrangement The results are discussed in connection with hypotheses of how selective attention affects the discriminability of a target.