Showing papers by "University of Utah published in 1968"

A head-mounted three dimensional display

Abstract: The fundamental idea behind the three-dimensional display is to present the user with a perspective image which changes as he moves. The retinal image of the real objects which we see is, after all, only two-dimensional. Thus if we can place suitable two-dimensional images on the observer's retinas, we can create the illusion that he is seeing a three-dimensional object. Although stereo presentation is important to the three-dimensional illusion, it is less important than the change that takes place in the image when the observer moves his head. The image presented by the three-dimensional display must change in exactly the way that the image of a real object would change for similar motions of the user's head. Psychologists have long known that moving perspective images appear strikingly three-dimensional even without stereo presentation; the three-dimensional display described in this paper depends heavily on this "kinetic depth effect."

The effect of a circular inclusion on the stresses around a line crack in a sheet under tension

Abstract: Based on the two-dimensional theory of elasticity and by the use of Muskhelishvili technique, the effect of a circular inclusion of different elastic material on the stress state around a line crack in an infinite plate subject to tension is discussed. Here, the circular inclusion is supposed to be on the line of prolongation of the crack. Numerical calculations were carried out and the variation of the crack-tip stress intensity factor due to the geometry and elastic properties of two media was clarified.

A clipping divider

Abstract: When compared with a drawing on paper, the pictures presented by today's computer display equipment are sadly lacking in resolution. Most modern display equipment uses 10 bit digital to analog converters, providing for display in a 1024 by 1024 square raster. The actual resolution available is usually somewhat less since adjacent spots or lines will overlap. Even large-screen displays have limited resolution, for although they give a bigger picture, they also draw wider lines so that the amount of material which can appear at one time is still limited. Users of larger paper drawings have become accustomed to having a great deal of material presented at once. The computer display scope alone cannot serve the many tasks which require relatively large drawings with fine details.

An electron microscope study of cells in the matrix and intermediate laminae of the cerebral hemisphere of the 45 mm rabbit embryo.

Abstract: The morphology and intercellular relations of cells in the matrix, lower intermediate, and upper intermediate laminae of the cerebral hemisphere of rabbit embryos was studied with the electron microscope. Models of cells reconstructed from serial sections confirm previous observations made with the Golgi technique. Most cells in the matrix lamina appear to be spongioblasts; there are relatively few neuroblasts and columnar epithelial cells. Neuroblasts predominate in the intermediate lamina. Their short processes are intercalated among axons and spongioblast processes in the lower part. A large process, the preapex, distinguishes nerve cells in the upper part of the intermediate lamina, and its orientation in the direction of movement suggests that it may actively participate in the migration of neuroblasts. Serial section analysis confirms the fact that mitotic cells in the matrix lamina are spherical and have no processes. Assuming that neuroblasts are incapable of further division, it seems probable that intermitotic germinal cells have the form of spongioblasts and columnar epithelial cells and that they give rise to neuroblasts and other spongioblasts.

Defects in Rutile. III. Optical and Electrical Properties of Impurities and Charge Carriers

Abstract: Optical absorption spectra of various OH (OD) complexes in rutile have been studied as a function of light polarization, impurity concentration, and temperature. It is shown that the ${\mathrm{H}}^{+}$ (${\mathrm{D}}^{+}$) occupies sites in the basal plane, probably displaced somewhat from \textonehalf{}00, and can associate with various +3 substitutional cations, causing a shift of the OH (OD) stretching vibration to higher frequencies. Harmonic and combination-mode absorption has also been observed. Detailed absorption spectra and their polarization dependence for conduction-band electrons and for electrons in an Fe impurity band are presented, and the strength of the absorptions is related to the carrier concentration. These spectra apparently result from intra- or interband transitions of electrons. In neither case is a simple Drude-type absorption (as in a metal) adequate to account for the spectra. Preliminary data on the Fe impurity band indicate conductivity g0.1 ${\mathrm{\ensuremath{\Omega}}}^{\ensuremath{-}1}$ ${\mathrm{cm}}^{\ensuremath{-}1}$ at room temperature for a carrier density of \ensuremath{\sim}7\ifmmode\times\else\texttimes\fi{}${10}^{19}$/${\mathrm{cm}}^{3}$. Qualitative information on diffusion and solubility of various cation impurities is given. These data and results presented in the preceding papers permit a fairly complete, though not yet quantitative, description of the electronic defect structure of rutile. In particular, it is concluded that rutile does not normally exhibit $p$-type conductivity, because of the ease of formation of ${\mathrm{Ti}}^{4+}$ interstitials; and that the donor defect in "reduced" rutile may be either ${\mathrm{Ti}}^{4+}$ or ${\mathrm{H}}^{+}$, depending on reduction temperature and ambient atmosphere, or may be any of a wide variety of metal impurities if these are present.

Hemolysin and Peroxide Activity of Mycoplasma Species

Abstract: Various methods for the detection of hemolysin production by Mycoplasma species were compared. Inoculation of blood-agar by the push-block method and by use of concentrated mycoplasma cell suspensions was compared with the agar-overlay technique. The preferred method was direct surface inoculation of concentrated suspensions onto the blood-agar. Among the conditions tested, refrigeration of 48-hr cultures gave the best results. A wide variety of mycoplasma species were tested for hemolytic activity towards rabbit, sheep, guinea pig, duck, and chicken bloods. Guinea pig erythrocytes were found to be the most susceptible to lysis by mycoplasma, and rabbit erythrocytes were found to be the least susceptible. A sensitive technique for the detection of peroxide production by mycoplasma strains, employing agar containing benzidine and sheep blood, was used. With this method, peroxide production could be correlated with hemolysis on blood-agar. Peroxidase and catalase inhibited both the benzidine reaction and hemolysis. It was concluded that the major hemolysin of the Mycoplasma species examined is a peroxide. Images

Dorsal root potentials and ventral root reflexes evoked by nonmyelinated fibers.

Abstract: Electrical stimulation of C-fibers in the cat superficial peroneal nerve, with the A-fibers either conducting or blocked by cold, evoked dorsal root potentials having the same polarity as those evoked by A-fibers. Ventral root reflexes evoked by A-fibers were facilitated by a pure C-volley in the same or another nerve, but dorsal root potentials evoked by A-fibers were reduced by isolated dorsal root potentials from C-fibers. In the absence of anesthetics, single C-volleys produced brisk and prolonged reflex discharges in ventral roots.

Computer-based monitoring of cardiovascular functions in postoperative patients

Abstract: INDUSTRIAL application of computers to complex control problems has led to speculation among the members of the medical profession regarding the possibility of computers monitoring acutely ill patients. A system directed toward this ultimate end has been in operation in the Latter-day Saints Hospital in Salt Lake City, Utah, since March, 1966. To date, 215 patients have been monitored with this system. Many of these patients developed complications which were detected by the computer system earlier than would have been the case by the usual methods of monitoring. Decisions regarding change of therapy were often made as a result of information gathered through the monitoring system. The system, operating 24 hours a day, seven days a week, has now established itself as an integral part of the postoperative care of open-heart surgery patients in this hospital and is well received by the patient, nurse, and physician alike. The purpose of this paper is to describe the goals of this project, techniques currently being used to achieve these goals, and experience with the system to date.

Dense-gas chromatography of nonvolatile substances of high molecular weight.

Abstract: Working at pressures of up to 2000 atmospheres, more than ten times higher than in previous gas chromatography, we used the solvent power of dense gases to enable migration of chromatographic substances of molecular weights as high as 400,000. Carotenoids, corticol steroids, sterols, nucleosides, amino acids, carbohydrates, and several polymers have been caused to migrate, separated, and detected in NH3 and CO2 carrier gases at temperatures of 140° and 40°C, just above the respective critical points. Previously such compounds either defied separation by gas chromatography or had to be chromatographed as their more volatile derivatives.

Light microscopy of glial cells in turtles and birds.

Abstract: Four classes of glial cells can be recognized in the central nervous system of turtles and birds on the basis of nuclear characteristics (methylene blue) and external morphology (Golgi technique). It seems likely that astrocytes and ependymal cells have a similar origin and function, but no evidence has been seen to indicate that transitional forms exist between astrocytes and oligodendrocytes or microgliacytes. Ependymal cells in the tectum and forebrain are covered by lamellate excrescences which are absent on cells in the spinal cord. Protoplasmic astrocytes are restricted to the gray matter. In the turtle they have an elongate shape characteristic of primitive elements, but stellate forms typical of mammals predominate in the bird. Fibrous astrocytes are abundant in the white matter. Endfeet are lacking in the turtle except on cells located near the pia; they are common for all elements in the bird and can sometimes be observed to outline the course of capillaries. Oligodendrocytes are identical to mammalian and amphibian forms. Small, round somata and long, thin processes are typical of types I and II while a tubular reticulum or membranous sheath characterizes type IV. The lack of a well defined somata and absence of transitional forms (type III) are compatible with the possibility that type IV is not a true cell type but corresponds to the inner cytoplasmic tongue of myelin. Microgliacytes are present in gray and white matter; they have a smaller overall size in the turtle and young chicken than in adult birds.

The effects of reinforcement on the modification, maintenance, and generalization of social responses of mental patients.

Abstract: Social greeting responses of three withdrawn, chronic schizophrenics were experimentally modified. Initially, none of the subjects spoke to an experimenter. Prompts and cigarette reinforcement were employed to produce increases in the rates of greetings. Then, the prompts were faded so that the greetings came under the control of the presence of the experimenter. Reversal and subsequent reinforcement procedures were employed to demonstrate that the responses were controlled by their consequences. Next, the schedule of cigarette reinforcement was leaned out so that greetings continued to occur in the absence of cigarette reinforcement. However, low or zero rates of greetings occurred in the presence of a second experimenter. Five new experimenters employed the prompting, fading, reinforcement, and schedule-leaning procedures. Subsequently, all subjects emitted appropriately high rates of greetings in the presence of the second experimenter. Without further application of the experimental procedures, greetings were still occurring in the presence of both the first and second experimenters almost three months later.

On Newton-like methods

Abstract: where x 0 is prechosen and M is some, not necessarily continuous, correspondence between /2 o and L(Y, X). For a practical problem, such as the simultaneous solution of nonlinear equations, NEWTON'S method is usually absurd because of the relative impossibility of doing the calculations necessary to find x,+ 1 exactly. Any number of expediencies suggest themselves, such as the use of a matr ix of difference approximations in place of the Jacobian matrix. Some very ingenious algorithms for the solution of this problem are given by BROYDEN [61 and BROWN and CONTE [7]. All the methods suggested there are of the type listed above. These two papers abound with excellent numerical examples illustrating the imminent practicality of these methods. Many authors have studied methods of this type. Among them [8] and [ t t ] s tudy the method as stated here and the bibliography is composed of references in which some variant of this method is studied. Many more could be listed. In [8], the author, by this approach, obtained a generalization of a theorem due to MYSOVSKIH [t2] on the convergence of NEWTON'S method and a convergence theorem for Newton-like methods. This latter theorem yielded only linear convergence. Here we present sufficient conditions on M(x) for the sequence of error bounds of the iteration to be of order p, 1 <=p<= 2.

Metabolism of Glycine in the Nonketotic Form of Hyperglycinemia

Abstract: Extract: Hyperglycinemia is a disorder of amino acid metabolism characterized by the presence of increased concentrations of glycine in the blood, urine, and cerebrospinal fluid. It is now recognized that there are two forms of hyperglycinemia each representing distinct diseases. These studies were designed to assess the metabolism of glycine in the nonketotic form of hyperglycinemia. Isotope content was assessed in respiratory CO2 and in glycine, serine and the β carbon of serine of plasma after the separate intravenous injections of glycine-I-14C and glycine-2-14C. The specific activities of 14CO2 isolated from expired air after the injection of glycine-1-14C (fig. 2) declined in control subjects from peak values at 10 to 15 minutes in nearly linear fashion over a 2-hour period. In contrast, curves obtained in the patients were rather flat, rising slowly after injection to highest values at about 60 minutes. At 15 minutes, values for the control individuals exceeded those of the patients by a factor of 5− to 10-fold. These data indicate a defect in the formation of 14CO2 from the first carbon of glycine. When the control subjects were infused with nonisotopic glycine to produce pools comparable to those found in the patient, the specific activities of the serine isolated from plasma after the injection of glycine-1-14C (table II) were virtually the same in both groups. The rate of conversion of glycine-2-14C to serine (fig. 3) in the patients was, however, considerably slower than it was in the control subjects for at least the first 30 minutes, and the curves were flat throughout. Degradation of the serine isolated from plasma and precipitation of the β carbon as formaldemethone indicated that the incorporation of the α carbon of glycine into the β carbon of serine was much higher in the controls than in the patients (fig. 4). The curves for the patients approximated the abscissa indicating virtually no conversion. These data indicate that in nonketotic hyperglycinemia there is a defect in the oxidation of carbon 1 of glycine to CO2 and in the conversion of carbon 2 of glycine to carbon 3 of serine. This is consistent with a defect in an enzyme catalyzing the transformation of glycine to CO2, NH3 and hydroxymethyltetrahydrofolate. Speculation: The data obtained indicate that patients with nonketotic hyperglycinemia are unable in vivo to convert the first carbon of glycine directly to CO2 and the second carbon of glycine to the third carbon of serine. This is consistent with a genetic defect in an enzyme which catalyzes decarboxylation and formation of hydroxymethyltetrahydrofolate from glycine. It should be possible to document such a defect at a cellular and subcellular level.

Magnitude and frequency of reinforcement and frequencies of interresponse times.

Abstract: The relative magnitude and relative frequency of reinforcement for two concurrent interresponse times (1.5 to 2.5 sec and 3.5 to 4.5 sec) were simultaneously varied in an experiment in which pigeons obtained grain by pecking on a single key. Visual discriminative stimuli accompanied the two time intervals in which reinforcements were arranged by a one-minute variable-interval schedule. The resulting interresponse times of each of three pigeons fell into two groups; "short" (1.0 to 2.5 sec) and "long" (3.0 to 4.5 sec). Steady-state relative frequencies of these interresponse times were orderly functions of both reinforcement variables. The combined effects of both independent variables were well summarized by a linear function of one variable, relative access to food. Unlike corresponding two-key concurrent variable-interval schedules, the present schedule did not produce an equality between the relative frequency of an operant and either the relative magnitude or the relative frequency of reinforcement of that operant. A tentative account is provided for this difference between one-key and two-key functions.

Neutrophil releasing activity in plasma of normal human subjects injected with endotoxin.

Abstract: SummaryNormal human subjects were injected with endotoxin and their plasma was harvested at various times thereafter. This plasma was later infused into the same subject, to determine if neutrophil...

Electron Irradiation and Recovery of Tungsten

Abstract: Damage rates and recovery of 99.99% pure tungsten have been investigated after electron irradiation near 4 °K by means of electrical resistivity. The damage rate data tend to a value of T0 = 38 to 42 eV. The recovery of the residual electrical resistivity shows three major stages: Stage I from 4.2 to 100 °K, Stage II from 100 to 500 °K, Stage III from 500 to 1000 °K. Stage I is dominated by only one major peak at 70 °K. An analysis based on second-order kinetics yielded a good fit to the data through 95% of the recovery. The energy derived was 0.17 eV. Only ≈ 26% recovery is seen in Stage I and we propose that the suppression is due to interstitial trapping by impurities. Stage III accounts for about 40% recovery of the induced resistivity and has a center temperature of 760 °K. The stage was analysed assuming second-order kinetics; this analysis gave an energy of 1.1 eV. Messungen der elektrischen Leitfahigkeit wurden benutzt, um Schadigungsraten und Erholungsverhalten von 99,99% reinem Wolfram nach Elektronenbestrahlung bei etwa 4 °K zu untersuchen. Die Mesergebnisse fur die Schadigungsraten lassen eine Verlagerungsenergie zwischen 38 und 42 eV vermuten. Die Erholung des elektrischen Restwiderstands weist drei grose Bereiche auf: Bereich I von 4,2 bis 100 °K, Bereich II von 100 bis 500 °K, Bereich III von 500 bis 1000 °K. Im Bereich I dominiert eine Stufe bei 70 °K. Die Mesdaten uber einen Bereich von 95% der Erholung in dieser Stufe stimmen gut mit einer Reaktion zweiter Ordnung uberein. Die Aktivierungsenergie wurde zu 0,17 eV ermittelt. Nur ≈ 26% der bestrahlungsinduzierten Widerstandsanderung heilen in Bereich I aus. Es wird vorgeschlagen, das der Einfang von Zwischengitteratomen durch Verunreinigungen eine Verkleinerung von Bereich I bewirkt. Etwa 40% der Erholung finden in Bereich III statt, dessen mittlere Temperatur bei 760 °K liegt. Dieser Bereich wurde unter der Annahme einer Kinetik zweiter Ordnung analysiert. Es wurde eine Aktivierungsenergie von 1,1 eV erhalten.

Ozone Needle Mottle of Pine in Southern California

Abstract: The specific type of chlorotic mottling in ponderosa pine needles, as reported by various workers,1,8,9 justifies the assumption that X-diesase, needle dieback, chlorotic decline, and ozone needle mottle in various pine species described in this paper are one and the same disease. Experimental production of chlorotic needle mottling in ponderosa pine (Pinus ponderosa Laws) with ozone-polluted ambient air and with synthesized ozone by Miller8 further justifies this basic assumption. Controlled fumigation studies (1959 and 1960 at the Citrus Research and Agricultural Experiment Station, Riverside, Calif.)15 confirm needle mottle of pine as a distinctive physiogenic disease, and atmopheric ozone as the prime etiological factor. Basic experimental research together with the wide range of field studies and observations by the present authors10,15 have clarified the type and sequence in symptom expression essential for diagnosis, and have greatly extended the range of pine species visibly susceptible to atmosph...

The surface tension of binary liquid mixtures.

Abstract: There are several theories of surface tension of liquid mixtures.'-3 From a quasi-lattice model for the liquid state, Guggenheim' derived the equation which relates the surface tension of a binary mixture to the activities of its components in the bulk liquid and in the surface. However, this equation can be applied only to mixtures whose components are similar in molecular size and shape. Prigogine et al.2' I developed their theory by treating the equilibrium surface tension of a mixture as a perturbation on the \"dynamic surface tension\" using a smoothed potential function. This theory is applicable only to very nearly ideal systems. Hildebrand and Scott's equation4 is an extension of Guggenheim's ideal equation, taking into account the molecular size effect. Recently, Eckert and Prausnitzb obtained an equation for the surface tension of simple nonpolar binary liquid mixtures using the cell theory and the grand partition function of the surface. They expressed the surface tension in terms of the activity coefficients of the components. Formally, the Eckert-Prausnitz equation is an improved Guggenheim equation. All the above mentioned theories, however, are limited in their use. There are several ways'ea for obtaining the surface tension of pure liquids from the significant structure theory of liquids. An extension of the approach to binary liquid mixtures is made in this paper by assuming that the approximation of random mixing is valid and that the surface of the mixture consists of a monomolecular layer which makes the principal contribution to the surface tension. The advantage of our equation is that it can be applied to any system. (1) Formulation of Equation of Surface Tension of Liquid Mixtures.-(a) Partition function: If we accept the approximation of random mixing of components of mixtures and that the chief contribution to the surface tension comes from a monomolecular surface layer, the partition function of a liquid mixture is given by 6bW

Artificial heart system and method of pumping blood by electromagnetically pulsed fluid

Abstract: AN ARTIFICIAL HEART SYSTEM INCLUDING METHOD AND APPARATUS, THE APPARATUS COMPRISING, PREFERABLY, TWO INTERCONNECTED VENTRICLES, EACH INTERNALLY PROVIDED WITH AN ACCUMULATOR DIAPHRAGM WHICH IS, ACCORDING TO THE METHOD, SERIALLY FLEXED IN RESPONSE TO PULSATILE DISPLACEMENT OF ELECTRICALLY CONDUCTIVE FLUID OTHER THAN BLOOD, THE DISPLACEMENT BEING DEVELOPED BY AN ELECTROMAGNETIC FLUID DRIVING DEVICE POWERED BY THERMOELECTRICALLY DERIVED ELECTRICAL ENERGY.

Coherent cosmic-ray model based on ''direct'' muon production.

Abstract: We consider a cosmic-ray muon model in which a "directly produced" muon component with the same slope as the primary spectrum is added to the conventional pion-derived muons. It is found to be consistent with recent burst measurements, horizontal-air-shower data, atmospheric gamma-ray fluxes, and muon spectrograph measurements. It may also explain the anomalous mu-less air showers. The model requires that the photonuclear cross section increase at very high energies.