Showing papers by "University of Utah published in 1976"

Special points for brillouin-zone integrations

Abstract: A method is given for generating sets of special points in the Brillouin zone which provides an efficient means of integrating periodic functions of the wave vector. The integration can be over the entire Brillouin zone or over specified portions thereof. This method also has applications in spectral and density-of-state calculations. The relationships to the Chadi-Cohen and Gilat-Raubenheimer methods are indicated.

Texture and reflection in computer generated images

Abstract: In 1974 Catmull developed a new algorithm for rendering images of bivariate surface patches. This paper describes extensions of this algorithm in the areas of texture simulation and lighting models. The parametrization of a patch defines a coordinate system which is used as a key for mapping patterns onto the surface. The intensity of the pattern at each picture element is computed as a weighted average of regions of the pattern definition function. The shape and size of this weighting function are chosen using digital signal processing theory. The patch rendering algorithm allows accurate computation of the surface normal to the patch at each picture element, permitting the simulation of mirror reflections. The amount of light coming from a given direction is modeled in a similar manner to the texture mapping and then added to the intensity obtained from the texture mapping. Several examples of images synthesized using these new techniques are included.

Why be an hermaphrodite

Abstract: MANY animals and most higher plants are hermaphrodites. The basic argument of this paper is that the sex habit of a species is determined by selection acting on the number of offspring produced by individuals of different types. The argument differs radically from most earlier explanations of the evolution of hermaphroditism (reviewed by Ghiselin)1,2, although it is formally similar to a recent explanation3 of sequential hermaphroditism, in which individuals function first as one sex and then the other.

Diagnosis and treatment of minimal brain dysfunction in adults: a preliminary report.

Abstract: • Minimal brain dysfunction (MBD) has long been considered a disorder limited to childhood. A number of longitudinal and adoption studies suggest that MBD may persist into adult life where its existence is concealed by the application of a variety of diagnostic labels. In order to test the hypothesis that MBD does persist into adulthood, 15 putative MBD adults were identified on the basis of current MBD-like complaints, self-description of MBD characteristics in childhood, and a parental rating (on a standardized form) of "hyperactivity" in childhood. Eleven of the 15 subjects were given a double-blind trial of methylphenidate hydrochloride, and all 15 were given an open trial of pemoline, imipramine hydrochloride, or amitryptiline hydrochloride. Eight of the 11 showed a significant response to the double-blind trial of methylphenidate. Of the 15, eight showed a good response to stimulants or tricyclic antidepressants, two showed a moderately favorable response, and five were unresponsive to drug therapy.

Toward a theory of personal space expectations and their violations

Abstract: Proxemics literature is synthesized and placed in a theoretical framework based on norms and expectations. Two major and three subordinate propositions are supported, and a model for predicting effects of violations of proxemic expectations is advanced. A sample of hypotheses generated from the model is included.

Flow-Field-Flow Fractionation: A Versatile New Separation Method

Abstract: Flow-field-fractionation is a new separation technique that seems likely to have broad applicability. Its theoretical scope includes any solute for which one can find a solvent and a semipermeable membrane. The principles on which the technique is based are presented. Some experiments with polystyrene beads, viruses, and proteins verify that retention depends solely on diffusion coefficients.

Issues underlying prevalence of "doctor-shopping" behavior.

Abstract: Data were collected on all persons within a sample of upper-and lower-income households who had seen physicians for illness episodes within a year prior to the interview. Forty-eight percent of upper-and 37 percent of lower-income families in the sample had changed doctors because of dissatisfaction with some aspect of the care. Factors related to tendency to shop for doctors in both upper-and lower-income groups were a lack of confidence in doctors' competence, unwillingness of doctors to spend time talking with patients, hostile feelings toward doctors, high cost of services, inconvenience of location and hours, and unfavorable attitudes toward doctors' personal qualities. Hypochondriasis was related to doctorshopping in the upper-income group. Results of this investigation suggest that patients may be becoming more discriminating in their choice of physicians.

Epidermal iontophoresis device

Abstract: An improved iontophoresis device for topical administration of ionic drugs or chemicals through epidermal tissue for anesthetizing or sterilizing local tissue or for applying various medicaments without mechanical penetration. An ionic form of drug is conducted through the epidermal tissue by means of direct current generated from a battery powered current source. Pulse-width modulated DC current is regulated by feedback circuitry which varies the pulse duration and adjusts and stabilizes the average current at a desired level. A high voltage capability together with feedback control enables maintenance of a constant current through the highly resistive epidermal tissue. To prevent excessive voltage buildup and the accompanying dangers of shock and burns, a comparator circuit monitors current flow and voltage across the electrodes and automatically triggers an SCR shutdown circuit when impedance readings are outside predetermined limits. The ionic drug is suspended in a conductive gel mixture which acts as the conducting medium in direct communication with the patient's skin. This gel is carried in a receptacle mounted on an electrode pad which uses a conducting foil surface to make electrical contact with the gel.

"Braille" reading by a blind volunteer by visual cortex stimulation.

Abstract: THE possibility of developing functional visual prostheses was supported by the pioneering case of Brindley and Lewin1,2 and confirmed by our subsequent report on two other blind patients3.

Diffuse reflectance from a finite blood medium: applications to the modeling of fiber optic catheters

Abstract: The scattering and absorption of light by randomly oriented, discretely scattering, red blood cells imbedded in a homogeneous plasma medium can be described by the P1 approximation to the one-speed transport equation, where the cells have the dual role of anisotropic sources for first scattering events and of scattering and absorption sites for subsequent scattering events. Equations for diffuse reflectance defined for a finite size receiver in the plane of a normally incident cylindrical photon beam are derived and compared with experimental data to fundamentally justify the basic sending-receiving characteristics of a fiber optic catheter model. A model of the fiber optic catheter used for the spectrophotometric measurement of oxygen content in blood is developed from the theory and compared with experimental results to further substantiate the theoretical approach.

Organization in memory and behavior.

Abstract: SOME COMMON REINFORCEMENT CONTINGENCIES MAKE THE DELIVERY OF A REINFORCER DEPEND ON THE OCCURRENCE OF BEHAVIOR LACKING SIGNIFICANT TEMPORAL STRUCTURE: a reinforcer may be contingent on nearly instantaneous responses such as a pigeon's key peck, a rat's lever press, a human's button press or brief verbal utterance, and so on. Such a reinforcement contingency conforms much more closely to the functionalist tradition in experimental psychology than to the structuralist tradition. Until recently, the functionalist tradition, in the form of a kind of associationism, typified most research on human learning and memory. Recently, however, research on human memory has focused more on structural issues: now the basic unit of analysis often involves an organized temporal pattern of behavior. A focus on the interrelations between the function and structure of behavior identifies a set of independent and dependent variables different from those identified by certain common kinds of "molar" behavioral analyses. In so doing, such a focus redefines some of the significant issues in the experimental analysis of behavior.

Analytic continuation of the holomorphic discrete series of a semi-simple Lie group

Abstract: O. Introduction In this paper, we are mainly interested in the construction of certain Hilbert spaces of holomorphic functions on an irreducible hermitian symmatric space D = G/K on which G acts by a natural unitary representation. Our construction will produce some new irreducible representations of the simple group G. In this introduction we shall indicate the nature of our methods and results, leaving the full statements to the text. We shall be looking at the unbounded realization of G/K, as a Siegel domain D = D(~2, Q) of type II; however our methods are here more easily explained for tube domains. Thus, in this introduction, we shall consider G/K as a tube domain D =R~§ c C ~, where ~2 is a homogeneous irreducible self-dual convex cone in R ~. We reiterate that our results appear, in the text, for the general case. Let G(~2)= {g E GL(R~), g(~)= ~}. Let G(D) be the connected component of the group of holomorphie transformations of D and ~(D) the universal covering of G(D). There is a natural unitary irreducible representation of G(D) on the I-Iilbert space of holomorphic functions on D which are square integrable, i.e., the Bergman space

Oncogenic transformation of human embryo lung cells by human cytomegalovirus.

Abstract: Persistent infection of human embryo lung fibroblasts with a genital isolate of cytomegalovirus resulted in oncogenic transformation of these cells. Immunofluorescence techniques detected virus-specific antigens, while microcytotoxicity tests established that the transformed cells share a membrane antigen with hamster cells transformed by inactivated cytomegalovirus. The transformed human cells induced progressively growing tumors in weanling athymic nude mice.

The design of a rotating associative memory for relational database applications

Abstract: The design and motivation for a rotating associative relational store (RARES) is described. RARES is designed to enhance the performance of an optimizing relational query interface by supporting important high level optimization techniques. In particular, it can perform tuple selection operations at the storage device and also can provide a mechanism for efficient sorting. Like other designs for rotating associative stores, RARES contains search logic which is attached to the heads of a rotating head-per-track storage device. RARES is distinct from other designs in that it utilizes a novel “orthogonal” storage layout. This layout allows a high output rate of selected tuples even when a sort order in the stored relation must be preserved. As in certain other designs, RARES can usually output a tuple as soon as it is found to satisfy the selection criteria. However, relative to these designs, the orthogonal layout allows an order of magnitude reduction in the capacity of storage local to the search logic.

A dielectric study of molecular relaxation in oxidized and chlorinated polyethylenes

Abstract: A study was made of the dielectric relaxation in polyethylenes rendered dielectrically active through oxidation (0.5–1.7 carbonyls/1000 CH2) and chlorination (14–22 Cl/1000 CH2). Both linear and branched polymers were studied. All of the relaxations between the melt and −196° were studied in the frequency range 10 Hz to 10kHz (100 kHz in the chlorinated samples). In the linear samples a wide range of crystallinities was studied (55% in quenched specimens to 95% in extended-chain specimens obtained by crystallization at 5 kbar). As is consistent with its being a crystalline process, the α peak was found to discontinously disappear on melting of the samples and reappear on recrystallizing on cooling. The disappearance of the smaller crystals before the larger ones appeared to be evident in the isothermal loss versus frequency curves. The relaxation strength of the α process increases with crystallinity. The measured relaxation strength is less than that expected on the basis of direct proportionality to the crystalline fraction with full contribution of all dipoles in the crystalline material. However, the intensity is not sufficiently low for the process to be interpreted in terms of reorientation of localized conformational defects in the crystal. The variation of intensity with crystallinity is best interpreted in terms of full participation of crystalline dipoles but with selective partitioning of both carbonyls and chlorines favoring the amorphous domains. A strong correlation of the α loss peak location (Tmax at constant frequency or log fmax at constant T) with crystallinity for both carbonyl and chlorine containing polymers was found. This variation is interpreted in terms of chain rotations in the crystal where the activation free energy depends on crystal thickness. The dependence of log fmax and Tmax on lamellar thickness as well as a comparison with the loss peaks of ketones dissolved in parafins indicates that the chain rotation is not rigid and is accompanied by twisting as the rotation propagates through the crystal. In agreement with previous studies the β process is found to be strong only in the branched polymers but can be detected in the chlorinated linear polymer. The β process was resolved from the α in the branched samples by curve fitting and its activation parameters determined. The γ relaxation peak in oxidized polymers including its high asymmetry (low-temperature tail) and increasing emax with increasing frequency and temperature when plotted isochronally can be interpreted in terms of a simple nearly symmetrical relaxation time spectrum that narrows with increasing temperature. No increase in relaxation strength with temperature was found. The chlorinated polymers behave similarly but appear to have some Boltzmann enhancement (450–750 cal/mole) of relaxation strength with temperature. The dependence of relaxation strength on crystallinity indicates that the process is an amorphous one. Further, no evidence of relaxation peak shape changes with crystallinity that could be interpreted in terms of a crystalline component in addition to the amorphous one was found. The comparison of the γ relaxation strength with that expected on the basis of full participation of amorphous dipoles indicates that only a small fraction (∼10% in oxidized linear polymers) of them are involved in the relaxation. Thus it would seem that a glass–rubber transition interpretation is not indicated but rather a localized chain motion. It is suggested that the γ process, including its intensity, width, and activation parameters, can be interpreted in terms of an (unspecified) localized conformational (bond rotation) motion that is perturbed by differing local packing environments. The thermal expansion lessens the effects of variations in packing and leads to narrowing with increasing temperature. The conformational motion itself leads to increase in thermal expansion and hence a transition in the latter property. Some previously proposed localized amorphous phase conformational motions appear to be suitable candidates for the bond rotation motion. A weak relaxation peak found at temperatures below the γ and at 10 kHz may possibly be the dielectric analog of the δ cryogenic peak found previously mechanically at lower frequencies.

CODASYL Data-Base Management Systems

Abstract: This paper presents in tutorial fashion the concepts, notation, aud data-base languages that were defined by the CODASYL Data Description Language and Programming Language Committees. Data structure diagram notation is explained, and sample data-base definition is developed along with several sample programs. \" Advanced features of the languages are discussed, together with examples of their use. An extensive bibliography is included.

Phytoplankton production in the Great Salt Lake, Utah, and a laboratory study of algal response to enrichment1

Abstract: The annual production by phytoplankton in the southern basin of the Great Salt Lake as estimated at two stations in 1973 averaged 145 g C m−2. The majority of the production occurred during March and April and was due to an unidentified species of Dunaliella. Daily carbon fixation rates averaged 2.13 g C m−2 at both locations during this period. A minor phytoplankton bloom in August, due to a small, unidentified green flagellate contributed 5% of the total annual phytoplankton production. Phytoplankton production was probably limited during April by self-shading and during the remainder of the year by the availability of nitrogen, as shown by laboratory bioassays. Grazing by Artemia salina reduces the phytoplankton population in late summer when nutrient levels have partially increased due to regeneration. The meromictic character of the lake was indicated by profiles of temperature and density. The monimolimnion is postulated to act as a nutrient sink, reducing the rate of nutrient release to the mixolimnion.

Short-term memory in the pigeon: relative recency.

Abstract: Three pigeons pecked for food in an experiment in which each trial consisted of two phases. The first phase consisted of a pattern of three successively illuminated, randomly selected left or right keys. A subject was required to peck each of the lighted keys as they appeared. Thus, in the first phase, a subject emitted a pattern of three left- or right-key pecks. Over trials, all eight possible patterns appeared. A time interval separated the first phase from the second phase, which began with presentation of a randomly selected one of three cues. A reinforcer was delivered in the second phase if a subject pecked the side key that had appeared in the first phase in an ordinal position corresponding to the cue presented in the second phase. That is, the three cues probed a pigeon's memory for the side key it had pecked first, second, or third, in the first phase of a trial. The results show that a pigeon can remember for more than 4 sec the order in which it has just seen and pecked two lighted keys: a pigeon can remember the temporal organization or pattern of events in its recent environment. Consequently, the functional stimulus present when a reinforcer is delivered may include a subject's short-term memory for the temporal organization of recent events, such as the pattern of its own recent behavior. This possibility is consistent with a molecular analysis of operant behavior focusing on local patterns of behavior.

Interpersonal Relationships and Personal Space: Research Review and Theoretical Model'

Abstract: This article reviews research concerning interpersonal distance as a function of interpersonal relationships, attraction, and reactions to spatial invasion. To integrate research findings, we propose a simple model, based on the idea that people seek an optimal distance from others that becomes smaller with friends and larger for individuals who do not expect to interact. The model describes comfort-discomfort as a function of interaction distance in three situations: interacting friends, interacting strangers, and strangers who do not expect interaction. These three personal space profiles are discussed in terms of qualifying variables, such as seated vs. standing interaction, sex composition of the dyad, intimacy of conversation topics, and situational variables.

Acoustic examination, material characterization and imaging of the internal structure of a body by measurement of the time-of-flight of acoustic energy therethrough

Abstract: Pulses of acoustic energy are transmitted from a plurality of different directions through a plane of interest, or a number of adjacent planes of interest, of a body to be examined. The body may be biological or non-biological. Time-of-flight of the pulses is measured for individual paths through the body, and from the data thus obtained the spatial distribution of the acoustic velocity through the plane or planes within the body is reconstructed using a mathematical reconstruction technique. The velocity values thus obtained, which are uniquely determinative of the acoustic index of refraction at each point, have diagnostic value, and they can further be displayed by means of a cathode ray tube or other imaging device to provide an image of the internal structure along each plane. The disclosed technique has the advantage of being highly independent of acoustic attenuation and reflections occurring along the paths.