Showing papers by "University of Delaware published in 1976"
TL;DR: A metabolic system composed of nucleic acid enzymes is proposed to have existed prior to the evolution of ribosomal protein synthesis, rationalizing the fact that many coenzymes are nucleotide or heterocyclic bases which could be derived from nucleotides.
Abstract: A metabolic system composed of nucleic acid enzymes is proposed to have existed prior to the evolution of ribosomal protein synthesis. Vestiges of these nucleic acid enzymes persist in contemporary coenzymes. This proposal rationalizes the fact that many coenzymes are nucleotides or heterocyclic bases which could be derived from nucleotides.
465 citations
TL;DR: The experimental observations and the extent of theoretical understanding of the instabilities in shear and extensional flows in polymeric liquids are discussed in this paper, where the experimental observations are compared with theoretical understanding.
Abstract: Instabilities which arise in shear and extensional flows in the processing of polymeric liquids are reviewed. The experimental observations and the extent of theoretical understanding of the instabilities are discussed.
406 citations
TL;DR: In this article, the enthalpy of dilution of all one-and two-solute aqueous mixtures of a series of compounds were measured from about 0.2 to 2.0 mole-kg−1 at 25°C.
Abstract: The enthalpy of dilution of all one-and two-solute aqueous mixtures of a series of compounds were measured from about 0.2 to 2.0 mole-kg−1 at 25°C. The compounds included in the study wereN-methylformamide,N-methylacetamide,N-methylpropionamide,N-butylacetamide, urea, ethylene glycol, pentaerythritol, glucose, and sucrose. The results of the enthalpy measurements were used to calculate the pairwise enthalpy of interaction for each compound with all the other compounds. A simple additivity principle is used to correlate the data. The principle assumes that each functional group on one molecule interacts with every functional group on the other molecule and that each of these interactions has a characteristic effect on the enthalpy that is independent of the positions of the functional groups in the two molecules. The resulting equation gives a rough but useful correlation of the results. Of the six interactions between the CH2, CONH, and CHOH functional groups, the CONH−CONH interaction is the strongest, the CHOH−CHOH interaction is the weakest, and the CH2−CH2 interaction is about equal in magnitude to the rest of the interactions. Thus, the CH2−CH2 and CONH−CONH are not the only interactions making important contributions to the enthalpy of a wide variety of systems.
324 citations
TL;DR: Destruction of the suprachiasmatic nuclei in the golden hamster by bilateral radiofrequency lesions abolishes three well-documented circadian rhythms--locomotor activity, estrous cyclicity, and photoperiodic photosensitivity.
Abstract: Destruction of the suprachiasmatic nuclei in the golden hamster by bilateral radiofrequency lesions abolishes three well-documented circadian rhythms--locomotor activity, estrous cyclicity, and photoperiodic photosensitivity. Entrainment of these rhythms by light cycles fails in lesioned hamsters; females become persistently estrous; in both sexes locomotor activity becomes sporadic, confined primarily to the light instead of darkness, and is totally arrhythmic when lesioned animals are exposed to continuous darkness; the photoperiodic gonadal response (gonadal regression induced by short day lengths) is abolished; lesioned animals remain reproductively mature irrespective of photoperiodic treatment.
277 citations
254 citations
TL;DR: The symbolic distance effect as mentioned in this paper has been shown to increase the time required to compare two symbols with respect to the distance between their referents on the judged dimension, by disentangling ordinal and interval distances between the referent of compared symbols.
241 citations
218 citations
TL;DR: In this paper, an iterative method is given for selecting the biasing parameter, k, in RIDGE regression, which produces a distribution of squared errors for the regression coefficients that has a smaller mean and a smaller variance than least squares or the single iteration estimate.
Abstract: An iterative method is given for selecting the biasing parameter, k, in RIDGE regression. The method produces a distribution of squared errors for the regression coefficients that has a smaller mean and a smaller variance than least squares or the single iteration estimate .
217 citations
TL;DR: In this article, the mechanics of isothermal melt spinning are studied for a viscoelastic liquid with a power law viscosity and a constant shear modulus, and the onset of the draw resonance instability, the magnitude of diameter fluctuations in the unstable region, and a second stable region at high draw ratio are predicted accurately.
Abstract: The mechanics of isothermal melt spinning are studied for a viscoelastic liquid with a power law viscosity and a constant shear modulus. Steady state velocities and stresses are in agreement with experiment. The onset of the draw resonance instability, the magnitude of diameter fluctuations in the unstable region, and a second stable region at high draw ratio are predicted accurately.
183 citations
TL;DR: Patients with right-hemisphere damage, who ostensibly have no linguistic impairment, are relatively incapable of solving two-term series problems in which comparative adjectives in the premise and question are antonymic, suggesting that verbal reasoning depends, in part, upon nonlinguistic imaginal processes subserved by the right hemisphere.
151 citations
TL;DR: In this article, a model for simultaneous heat transfer, mass transfer, and chemical reaction in the oxidation of carbon monoxide over platinum containing monoliths is presented. But the model is not suitable for predicting the behavior of the Nusselt number.
Abstract: Mathematical models are developed which account for simultaneous heat transfer, mass transfer, and chemical reaction in the oxidation of carbon monoxide over platinum containing monoliths. A two-dimensional model is shown to predict unusual behavior of the Nusselt number in the presence of rapid reaction. However, a simpler one-dimensional model is adequate for predicting monolith behavior.
TL;DR: The results suggest that sensation seekers may be characterized as having strong excitatory CNS processes, which are consistent with findings by others using anxiety neurotics as subjects.
Abstract: The relationship between sensation seeking and the orienting reflex (OR) using skin conductance change is investigated in two experiments. In Experiment I, high sensation seekers gave a greater initial OR In novel visual stimuli while not differing in habituation on subsequent trials. In Experiment II. the paradigm was extended to include auditory as well as visual stimuli. Again, high sensation seekers were found to be more arousable with respect to initial ORs while not differing in habituation rates. The results suggest that sensation seekers may be characterized as having strong excitatory CNS processes. In Experiment II, anxiety (trait and state) was also related to the OR. There were no effects due to trait anxiety but state anxiety did yield significant differences. The more highly anxious (state) subjects had weaker initial ORs than lows in both novel tones, but not to repeated tones. The findings with state anxiety are consistent with findings by others using anxiety neurotics as subjects.
TL;DR: In this paper, a unified treatment of the hygrothermal response of the laminated composite plate element is derived, which develops effective mois ture inplane force resultants and bending resultants, which when coupled with mechanical and thermal loadings, yield laminae stresses resulting from the total...
Abstract: The hygroscopic nature of polymeric systems, which find widespread application as matrices in advanced composite materials, requires that dila tations induced by the absorption of moisture be considered m the stress analysis of composite laminates. Considerable attention has recently been focused upon the reduction m both strength and constitutive properties of fiber-reinforced polymeric composites at elevated temperatures when the composite has been subjected to environments which enhance moisture diffusion. This apparent degradation in elevated temperature properties may be magnified even more by residual stresses induced by both the hygroscopic and thermoelastic characteristics of the unidirectional com posite.A unified treatment of the hygrothermal response of the laminated composite plate element is derived. The analysis develops effective mois ture inplane force resultants and bending resultants, which when coupled with mechanical and thermal loadings, yield laminae stresses resulting from the total...
TL;DR: It is proposed that evolutionarily significant substitutions may be identified by monitoring changes in functional density and weighted functional density, and it is shown that a certain category of changes in the internal environment of the organism can be integrated into the constantenvironment model for selection.
Abstract: The distinction between molecular sites that mainly carry out general functions and sites committed to specific functions is analyzed, notably in terms of different evolutionary variabilities. Functional density is defined as the proportion of sites involved in specific functions. Weighted functional density, by representing the relative variability at specific-function sites is to some extent a measure of the specificity of molecular interactions. The relationship between general- and specific-function sites on the one hand the covarions of Fitch on the other is discussed. The functional "degeneracy" of amino acids is described as increasing the interdependence of general functions. It is predicted that proteins tht do not possess general-function sites besides their specific-function sites tend to "freeze" their primary structure, according to an evolutionary process that is an autocatalytic function of the decrease in site variability. This limits the use of weighted functional density as an indicator of the overall degree of interaction specificity of a protein to values that are not close to unity.
TL;DR: By considering that the electrostatic charge on biological surfaces arises from the presence of multiple ionizable groups, the surface potential of and double-layer force between two plane surfaces were evaluated by numerically solving the non-linear Poisson-Boltzmann equation.
TL;DR: Treatment of endothelial cells with tannic acid-glutaraldehyde results in an increase in thickness and electron density of the outer leaflet of surface membranes, and the dependency of this effect upon subsequent staining with heavy metals indicates that enhanced density results from binding of heavy metals to sites of tannics acid deposition at the cell surface.
TL;DR: In this paper, the problem of rupture of a thin liquid film flowing down a vertical surface is considered, and it is assumed that both the continuous film and the rivulets carry the same mass flow and total (surface plus kinetic) energy.
TL;DR: Third-order neurons from the pontine taste area (PTA) were analyzed and it was concluded that the PTA is functionally as well as anatomically intermediate between the solitary nucleus and thalamus in the taste processing chain.
TL;DR: In this article, a simulation study of the relative impact of due-date assignment, dispatching and labor assignment decision rules on the performance of a dual-constrained job shop is presented.
Abstract: This paper describes a simulation study of the relative impact of due-date assignment, dispatching and labor assignment decision rules on the performance of a hypothetical dual-constrained job shop. Six criteria are used to measure the performance of the decision rules. They are mean flow-time, variance of flow-time, mean lateness, variance of lateness, proportion of jobs late, and total labor transfers.
Multiple regression is the principal method of analysis of the results of the experiments. This technique provides regression coefficients and analysis of variance statistics for the decision rules for the various performance measures. Since the objective of this study is to go beyond simple statements of the significance of the various decision rules, the multiple regression results are used with analysis of variance statistics to indicate the relative impact of the decision rules. The regression coefficients and the omega squared ω2 indices [Hays, W. L. 1962. Statistics. Holt, Rinehart and Winston, New York, 406--408.] indicate that the relative importance of the due-date assignment, dispatching and labor assignment decision rules is dependent upon the measure of performance considered. In addition, the relative importance and optimality of the dispatching rules is dependent upon the due-date tightness for selected performance measures.
TL;DR: In this paper, a unified theoretical framework is developed to study the stability of stagnant films having a wide range of thicknesses and located on a solid surface immersed in a viscous fluid.
TL;DR: The subjective weights an organizational buyer gave to different cues were estimated by regression procedures with data from an in-office product-concept evaluation task to provide insight on the validity of cue-weighting evidence gathered under field conditions.
Abstract: The subjective weights an organizational buyer gave to different cues were estimated by regression procedures with data from an in-office product-concept evaluation task. Multiple validity tests of the estimated weighting coefficients were performed including cross-validations, comparisons with a “known-groups” model, and comparisons with self-reports. The effects on the estimated models of variations in the product-concept profiles used in the task also were examined. The results provide insight on the validity of cue-weighting evidence gathered under field conditions.
TL;DR: Five species of unicellular algae of the same age, cultured bacteria-free under standard growth conditions, were analyzed for chemical composition and fed to different size classes of Artemia salina, finding growth, survival, rate of sexual maturtion, and sex ratio were dependent on the growth and assimilation efficiencies obtained from each respective algal food.
Abstract: Five species of unicellular algae of the same age, cultured bacteria-free under standard growth conditions, were analyzed for chemical composition and fed to different size classes of Artemia salina. The green algae Chlamydomonas sphagnicolo, Dunaliella viridis, Platymonas elliptica and Chlorella conductrix had significantly higher percentages of protein and lipid than did the diatom Nitzschia closterium. Total ash value was highest in populations of N. closterium. Shrimp fed Chlamydomonas sphagnicolo cells assimilated highest percentages of organic matter, while those fed Chlorella conductrix had lowest assimilation rate. Respiration rates were inversely proportional to animal size (weight) and algal cell volume. Growth, survival, rate of sexual maturtion, and sex ratio were dependent on the growth and assimilation efficiencies obtained from each respective algal food. Shrimp fed Chlamydomonas sphagnicolo, D. viridis, or P. elliptica cells displayed highest growth and assimilation efficiencies.
TL;DR: In this paper, the deactivation of 2.0-15 nm Pt crystallites supported on alumina and Pt black was studied in a fixed-bed differential reactor during NH 3 oxidation by molecular oxygen between 368 and 473 °K.
TL;DR: On the basis of data from seven cruises in the Amazon River-Atlantic Ocean area, and with 14 anchored stations extending over complete tidal cycles, the currents, suspended sediment concentration, temperature, and salinity were measured at various depths as mentioned in this paper.
Abstract: On the basis of data from seven cruises in the Amazon River–Atlantic Ocean area, and with 14 anchored stations extending over complete tidal cycles, the currents, suspended sediment concentration, temperature, and salinity were measured at various depths. The physical circulation of water shows Amazon River water thrusting out across the continental shelf and over the sea water with some entrainment and mixing with the sea water. The brackish plume from the Amazon is then turned northwestward along the outer shelf by the Guiana current and longshore currents to parallel the coastline for 500 to 700 km. Sea water upwells and flows landward under this plume. The sediments of the Amazon River are thrust out onto the outer shelf, where a gradual depositional process occurs: the sand is deposited first, followed by the silt, and most of the mud is carried shoreward by the landward-moving bottom waters. This combination of processes results in the existing depositional facies pattern; modern mud deposits along the shoreline grade outward into silt deposits and finally into modern sand. The depositional process occurring is contrary to the classic model with sand along the shoreline.
TL;DR: In this paper, the density dependence of the electron surface barrier for planar gold surfaces was determined by injection of electrons into the liquid and the dense vapor phases, and the results were consistent with a Wigner-Seitz calculation for atomic densities up to the experimental limit.
Abstract: The density dependence of the electron surface barrier for $^{3}\mathrm{He}$ and $^{4}\mathrm{He}$ fluids has been determined by injection of electrons from a planar gold surface into the liquid and the dense vapor phases. Barrier values for both isotopes are consistent with a Wigner-Seitz calculation for atomic densities up to the experimental limit of 1.8 \ifmmode\times\else\texttimes\fi{} ${10}^{22}$ ${\mathrm{cm}}^{\ensuremath{-}3}$ ($^{3}\mathrm{He}$) and 3.0 \ifmmode\times\else\texttimes\fi{} ${10}^{22}$ ${\mathrm{cm}}^{\ensuremath{-}3}$ ($^{4}\mathrm{He}$). Comparison of results with other theoretical and experimental values is presented.
TL;DR: In this paper, the physical basis of microanalysis using measurements of electron energy losses associated with atom ionization or plasmon excitation in thin electron microscope specimens is explained in a simple manner.
Abstract: SUMMARY
The physical basis of microanalysis using measurements of electron energy losses associated with atom ionization or plasmon excitation in thin electron microscope specimens is explained in a simple manner. In addition the equipment used to resolve both the high and low energy regions of the loss electron spectrum is described. It is shown that ionization loss analysis is still in its infancy, but plasmon loss analysis has now been providing quantitative microanalytical data on light metal alloys for 8 years. The results obtained from both techniques and their application to specific metallurgical problems are reviewed. Conclusions are drawn concerning the future use of these techniques in high resolution microanalysis.