Showing papers by "University of Delaware published in 1970"
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TL;DR: In this paper, the use of ridge regression methods is discussed and recommendations are made for obtaining a better regression equation than that given by ordinary least squares estimation. But the authors focus on the RIDGE TRACE which is a two-dimensional graphical procedure for portraying the complex relationships in multifactor data.
Abstract: This paper is an exposition of the use of ridge regression methods. Two examples from the literature are used as a base. Attention is focused on the RIDGE TRACE which is a two-dimensional graphical procedure for portraying the complex relationships in multifactor data. Recommendations are made for obtaining a better regression equation than that given by ordinary least squares estimation.
2,345 citations
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TL;DR: In this article, it was shown that the kinematics of the velocity field in this apparatus are approximately those of Lagrangian-unsteady extensional deformations, and the results are consequently of interest in distinguishing between alternate constitutive predictions of the stress levels in extensional flows, and in fluid mechanical applications in which such deformation fields occur.
Abstract: Direct measurements have been made of the stress levels developed in viscoelastic media issuing from small orifices at high velocities. Previous studies have shown the kinematics of the velocity field in this apparatus to be approximately those ofLagrangian-unsteady extensional deformations; the results are consequently of interest in distinguishing between alternate constitutive predictions of the stress levels in extensional flows, and in fluid mechanical applications in which such deformation fields occur. The ratio of the elongational viscosity to the shear viscosity, equal to three for Newtonian fluids, is seen to vary between 270 and 1730 for the several polymeric fluids studied, when estimates of deformation rate which lead to the most conservative values of this ratio are employed. Alternate and more probable estimates of the actual deformation rate levels yield ratios as great as 29,000. The apparatus described would appear to be useful for quantitative rheological studies of extensional flows provided data of the kind reported are accompanied by measurements of the velocity field, so that the deformation rate levels, their spatial variation and any attendant momentum corrections are all known precisely. While such velocity measurements are tedious to obtain no alternative for the direct study of rapid extensional flows appears to be available and in this light the suggestion may not be unattractive.
180 citations
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TL;DR: It was concluded that the findings of the present experiment can be explained most parsimoniously in terms of increased sensitivity of REM-deprived subjects to environmental stimulation.
Abstract: Four experiments were performed to test the behavioral effects of REM deprivation on rats. Two studies of avoidance learning showed that shuttle avoidance and runway avoidance were unaffected by REM deprivation. REM deprivation produced an enhancement of activity, and the addition of periodic shock demonstrated a failure of adaptation for REM-deprived subjects.
These data were interpreted as indicating that REM deprivation produces motivational effects on rat behavior and that electric shock-induced pain and REM deprivation interact to change activity patterns. It was concluded that the findings of the present experiment can be explained most parsimoniously in terms of increased sensitivity of REM-deprived subjects to environmental stimulation.
124 citations
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111 citations
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TL;DR: In the earliest stages of the development of mouse embryos, RNA synthesis can be blocked without inhibition of protein synthesis; but stopping protein synthesis depresses RNA synthesis.
Abstract: In the earliest stages of the development of mouse embryos, RNA synthesis can be blocked without inhibition of protein synthesis; but stopping protein synthesis depresses RNA synthesis.
85 citations
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TL;DR: In this paper, Coulomb-attractive centers due to a deformation of the potential around the center and induced by the external field are estimated, using a classical model, and are given as a function of the external force.
Abstract: At field strengths which can lie markedly below the critical values for impact ionization and Zener extraction, field induced changes in the capture cross section, barrier height, and frequency factor of Coulomb-attractive centers due to a deformation of the potential around the center and induced by the external field can cause a marked redistribution of carriers over these centers (field-enhanced ionization). These changes in the kinetic parameters of the centers are estimated, using a classical model, and are given as a function of the external field. For a typical semiconductor at T = 200 °K, a possible decrease of trap-occupation up to a factor of two, already, at fields of the order of 102 V/cm is calculated.
Fur Feldstarken, die betrachtlich unterhalb der kritischen Werte fur Stosionisation und fur Feldemission liegen, konnen feldbedingte Anderungen des Einfangquerschnittes, der Barrierenhohe und des Frequenzfaktors von Coulomb-attraktiven Zentren, verursacht durch eine Potentialdeformation in der Nahe des Zentrums durch das ausere elektrische Feld, eine merkliche Umverteilung von Ladungstragern uber diese Zentren hervorrufen („field-enhanced ionization”). Die Anderungen der kinetischen Parameter dieser Zentren werden in einem klassischen Modell und als Funktion des auseren Feldes angegeben. Es wird ausgerechnet, das fur einen typischen Halbleiter bei T = 200 °K die Hafttermbesetzung bis um einen Faktor zwei schon bei Feldstarken in der Nahe von 100 V/cm absinken kann.
82 citations
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TL;DR: The relatively minor instrumental modifications necessary to allow the operation of a CEC-21-110B mass spectrometer at pressures as high as 0·5 torr are discussed in this article.
Abstract: The relatively minor instrumental modifications necessary to allow the operation of a CEC-21-110B mass spectrometer at pressures as high as 0·5 torr are discussed. The chemical ionization mass spectra of a series of substituted benzophenones have been investigated with several reactant gases: methane, ethane, propane and isobutane. The spectra and behavior of these gases are discussed in general and the specific fragmentation processes of these substituted benzophenones with propane are presented in some detail.
55 citations
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TL;DR: In this article, simple rules are developed to estimate the maximum uplift pressures induced on the underside of a flat plate by various types of incident waves, including standing waves, regular progressive waves, and dispersive waves.
Abstract: Simple rules are developed to estimate the maximum uplift pressures induced on the underside of a flat plate by various types of incident waves. Theoretical prediction techniques are provided for both the slow-rise pressure component and the fast-rise pressure component (impact) for different incident waves: standing waves, regular progressive waves, and dispersive waves, all in constant water depth. Laboratory experiments were conducted in a dispersive wave basin partially to check the validity of prediction techniques and partially to provide additional information so that the prediction techniques can be extended empirically to cover the more complicated but more practical situation of a plate in shoaling water. The fast-rise pressure should be of engineering concern not only because the magnitude of its peak is enormous but also because the magnitude of the corresponding impulse is significant. The slow-rise pressure component was found to range from one to two times the hydrostatic pressure.
52 citations
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51 citations
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40 citations
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TL;DR: Colors, sizes and distribution of retinal oil globules differ in the two species of turtles investigated, and Pseudemys has an additional concentration in the inferior temporal area, and area which can participate in binocular vision, whileChelonia has no such concentration.
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TL;DR: In this paper, a two-phase isotropic homogeneous poroelastic material is taken as a model of the living bone in the sense that the osseous tissue is considered as a linear perfectly elastic solid and the fluid substances filling the cavities as a Newtonian viscous fluid.
Abstract: Two-phase isotropic homogeneous poroelastic material is taken as a model of the living bone in the sense that the osseous tissue is considered as a linear perfectly elastic solid and the fluid substances filling the cavities as a Newtonian viscous fluid. Using the Heinrich-Desoyer formulation of the consolidation theory of Terzaghi-Biot adapted to the spherical bodies and the Laplace transformation, the pressure head function is determined first. The complimentary solution of the equation for the displacement of the solid phase is then adapted from the classical elastic solution in terms of the Legendre polynomials. For simplicity, only the axisymmetric case is considered. The integration constants are determined from the third governing equation as well as from the boundary and initial conditions. Three illustrative examples are investigated in detail, assuming hydrostatic load: (1) a thick-walled shell if the fluid pressure may be disregarded, (2) a solid poroelastic sphere, (3) a thin-walled poroelastic shell. In case 2, the rheological model describing the behavior of the body seems to correspond to the Kelvin-Voigt model proposed for osseous tissues by Zarek and Edwards.
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TL;DR: Fecal pellets voided by 70 invertebrate species are described, 66 of these for the first time, and cross-sectional shape, sculpture, differentiation, composition, and shape are described.
Abstract: Fecal pellets voided by 70 invertebrate species are described, 66 of these for the first time. Pellet size is related to size of animals, and linear regressions are given for two species. Pellet characteristics described are cross-sectional shape, sculpture, differentiation, composition, and shape. The morphology is specific for many animals. However, certain species void feces which are 1) diffuse, 2) morphologically inconsistent, or 3) lack differentiating characteristics.
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TL;DR: Along the western shore of Delaware Bay, the polychaetous annelid Sabellaria vulgaris builds reefs which are formed of sand grains cemented together in rounded masses of dwelling tubes as discussed by the authors.
Abstract: Along the western shore of Delaware Bay the polychaetous annelidSabellaria vulgaris builds reefs which are formed of sand grains cemented together in rounded masses of dwelling tubes. They occur principally near the low tide line on sandy beaches in the lower part of the bay, where higher salinity waters, turbulence from wave action, a supply of sand, and a firm or hard substrate occur together. These reefs have important geological and biological effects on the immediate environment, modifying and stabilizing beach sediments, and supporting a distinct community of associated organisms.
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TL;DR: In this paper, the authors examined droplet movement and its effect on the liquid film in annular two-phase flow and found that droplet formation and movement both axially and circumferentially were investigated by using transient techniques.
Abstract: The liquid film in annular two-phase flow is maintained by droplet movement to and from the gas core and by wave action. This work examines droplet movement and its effect on the liquid film. Film formation and movement both axially and circumferentially were investigated by using transient techniques.
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TL;DR: In this article, it was shown that the observed steep decrease of the electron density in photoconducting CdS(Al, Ag) with field in the range between 20 and 70 kV/cm is caused by a redistribution of holes from slow to fast recombination centers (field quenching).
Abstract: It is shown that the observed steep decrease of the electron density in photoconducting CdS(Al, Ag) with field in the range between 20 and 70 kV/cm is caused by a redistribution of holes from slow to fast recombination centres (field quenching). This redistribution is produced by field-enhanced ionization of holes from Coulomb-attractive slow recombination centers. The abrupt onset of the field quenching occurs because of the slow recombination traffic masking the fast center traffic until it becomes predominant. Competing infrared quenching reduces the masking effect and uncovers the earlier phases of field quenching already near 1 kV/cm (at 200 °K). Impact ionization and Zener extraction of holes from slow centers cannot explain the observed behavior. However, quantitative agreement between experiment and field quenching via field-enhanced ionization can be reached.
Es wird gezeigt, das der steile Abfall der Elektronenkonzentration in photoleitendem CdS(Al, Ag) mit dem elektrischen Feld zwischen 20 und 70 kV/cm durch eine Umverteilung von Lochern von langsamen zu schnellen Rekombinationszentren verursacht wird (Feldtilgung). Diese Umverteilung wird durch „field-enhanced ionization” von Lochern aus Coulomb-attraktiven langsamen Zentren verursacht. Der abrupte Einsatz der Feldtilgung tritt auf, weil die langsame Rekombination eine Rekombination uber schnelle Zentren ver-deckt, bis diese uberwiegt. Eine konkurrierende Infrarottilgung vermindert den Verdeckungseffekt und macht eine fruhere Phase der Feldtilgung bereits in der Nahe von 1 kV/cm sichtbar. Eine Stosionisation oder Feldemission von Lochern aus langsamen Zentren kann das experimentell beobachtete Verhalten nicht erklaren; jedoch kann eine quantitative Ubereinstimmungzwisehen Experiment und Feldtilgung durch „field-enhanced ionization” erreicht werden.
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TL;DR: In this paper, the optical absorption spectra of twinned cubic cubic crystals of chromium-doped zinc sulfide between 5000 and 29 000 µm (2-0.34 µm) at 4.2-500 µm.
Abstract: We have measured the optical absorption spectra of twinned cubic crystals of chromiumdoped zinc sulfide between 5000 and 29 000 ${\mathrm{cm}}^{\ensuremath{-}1}$ (2-0.34 \ensuremath{\mu}m) at 4.2-500\ifmmode^\circ\else\textdegree\fi{}K. Two broad absorption bands are specific to chromium; at 77\ifmmode^\circ\else\textdegree\fi{}K, one has a maximum at 24 400 ${\mathrm{cm}}^{\ensuremath{-}1}$, the other, at 5700 ${\mathrm{cm}}^{\ensuremath{-}1}$. Weak photoconductivity is observed in the former; but none in the latter. Twelve narrow bands between 5100 and 5250 ${\mathrm{cm}}^{\ensuremath{-}1}$ are identified as zero-phonon transitions in ${\mathrm{Cr}}^{2+}$ (3${\mathrm{d}}^{4}$) substitutional at cation sites, two for the cubic structure, ten for the twin boundaries. The cubic crystal field is determined. Thirteen phonon-assisted transitions are identified and the phonon wave numbers are evaluated. We propose that the 24 400-${\mathrm{cm}}^{\ensuremath{-}1}$ band involves transitions to the conduction band edge.
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TL;DR: The results are interpreted as being evidence for the genetic control of adult-life span as a function of the total developmental pattern of the organism.
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TL;DR: In this article, the authors considered resonance transfer from effective mass electronic states of donor-acceptor pairs to tightly-bound states of impurities in semiconductors and showed that the transfer matrix depends on the overlap of the effective mass function of donor and acceptor.
Abstract: After briefly reviewing the formulation of resonance energy transfer, we consider resonance transfer from effective mass electronic states of donor-acceptor pairs to tightly-bound electronic states of impurities in semiconductors. Two general cases requiring different theoretical analyses are considered: 1. transfer from the donor-acceptor pair to a distant point fluorescer and 2. transfer from the pair to intra-core fluorescer states of the donor or acceptor. The energy transfer matrices for both cases are shown to depend on the radiative transition matrix for the fluorescer. For case 1, the transfer matrix depends on the overlap of the effective mass function of donor and acceptor; for case 2 the main contribution arises from effective mass functions in the unit cell within which is the fluorescer core. The analyses are applied qualitatively to ZnS:Cu, Ga, Mn and to ZnS:Cu, Tb, and comparisons made with other transfer mechanisms. Finally, transfer involving intra-donor transitions is predicted.
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TL;DR: In this article, the mobility of carriers at different energies is discussed and it is shown that hopping conductivity competes unfavorably with a conductivity higher inside the bands, which is not in contradiction to the measured small values of the Hall effect in semiconducting glasses, as pointed out earlier.
Abstract: The mobility of carriers at different energies is discussed and it is shown that hopping conductivity competes unfavorably with a conductivity higher inside the bands. The magnitude of the carrier mobility is estimated as a function of the carrier energy and it is shown that an effective carrier mobility of the order of 100 cm2/V sec can be expected even in highly disordered structures of predominately covalently bonded materials. These high mobilities are not in contradiction to the measured small values of the Hall-effect in semiconducting glasses, as pointed out earlier, because of the potential barriers caused by Coulomb-repulsive centers and of the essentially ambipolar character of the conductivity. Moreover, some additional evidence of a high carrier mobility is given by analysing the carrier transport during switching of Ovonic devices, yielding essentially the same order of magnitude for the carrier mobility (100 cm2/V sec).
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TL;DR: In this article, it was suggested that the carrier mobility of semiconducting glasses is considerably larger than the Hall-mobility because of potential perturbations due to a large density of charged defects and because of the ambipolar character of the conductivity.
Abstract: It is suggested that the carrier mobility of semiconducting glasses is considerably larger than the Hall-mobility because of potential perturbations due to a large density of charged defects and because of the ambipolar character of the conductivity. These potential perturbations force the main carrier transport to occur farther inside the bands at a distance E from the band edges, which is essentially given by the height of potential saddles between Coulomb-repulsive defects E ⋍ 0.2 eV for N rep. ⋍ 10 19 cm −3 ) , explaining the larger slope of the semiconductivity. The mean free path of carriers is estimated to be of the order of 100 A in agreement with the large pre-exponential factor of the semiconductivity. The Seebeck-effect—Hall-effect anomaly and the p-type semiconductivity can be explained due to the difference in effective masses of holes and electrons in simple bands.
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TL;DR: In this article, it was shown that the aging characteristics depend on spherulite size and that indeed the spherule size effects reported by others very likely reflect chain rearrangements upon aging, rather than some property associated with the as-crystallized material.
Abstract: The mechanical behavior of isotactic polypropylene following primary crystallization is known to be dependent on the aging time (e.g., at room temperature). This aging time effect is believed to be related to a form of additional crystallization (sometimes called secondary crystallization). We show in the present work that the aging characteristics depend on spherulite size and that indeed the spherulite size effects reported by others very likely reflect chain rearrangements upon aging, rather than some property associated with the as-crystallized material.
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TL;DR: In this article, a simple change of the conduction mechanism, as the barriers are rendered ineffective at elevated temperatures, during the switching transition is suggested for explanation of the Ovshinsky effect.
Abstract: Potential perturbations caused by about 1020 cm-3 of charged defects are characteristic for real glasses and cause a marked reduction of the mobility near the mobility edge as compared to ideal glasses. The conduction mechanism in real glasses is suggested to be carrier drift at a conductivity edge over barriers provided by Coulomb-repulsive defects. Evidence is given by analysis of numerous optical and electrical properties that the carrier mobility is of the order of 102 cm2/Vs in spite of a Hall mobility which is at least three orders of magnitude smaller. A simple change of the conduction mechanism, as the barriers are rendered ineffective at elevated temperatures, during the switching transition is suggested for explanation of the Ovshinsky effect.
Potentialverbiegungen, die durch etwa 1020 cm-3 geladene Storstellen hervorgerufen werden, sind charakteristisch fur ein Realglas und verursachen eine betrachtliche Verminderung der Beweglichkeit an der Beweglichkeitskante, verglichen mit einem Idealglas. Es wird vorgeschlagen, das der Leitungsmechanismus durch Stromtragerdrift an der Leitfahigkeitskante erklart wird, die uber Barrieren hinweg funktioniert, welche durch Coulombrepulsive Zentren erzeugt werden. Durch die Analyse zahlreicher optischer und elektrischer Eigenschaften werden Hinweise dafur gegeben, das die Stromtragerbeweglichkeit von der Grosenordnung 102 cm2/Vs ist, obwohl die Hallbeweglichkeit mehr als drei Grosenordnungen kleiner ist. Ein einfacher Wechsel im Leitungsmechanismus durch Unwirksamwerden der Barrieren bei hoheren Temperaturen wahrend des Schaltvorganges wird zur Erklarung des Ovshinsky-Effektes vorgeschlagen.
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TL;DR: In this article, the time necessary to reach a critical temperature by Joule's heating after switching-on a certain voltage (delay time) is calculated, using the thermal balance equation in an essentially one-dimensional sandwich of a semiconducting glass, which is imbedded in a spherical material of high heat conductivity.
Abstract: Assuming that a critical temperature must be reached for initiating of the electronic switching process, the time necessary to reach this temperature by Joule's heating after switching-on a certain voltage (delay time) is calculated, using the thermal balance equation in an essentially one-dimensional sandwich of a semiconducting glass, which is imbedded in a spherical material of high heat conductivity (electrodes). It is shown that the delay time for high overvoltages decreases exponentially with the same slope as the conductivity increases with voltage. Near the critical voltage a steep increase of the delay time results. The thermal conductivity of the glass can be obtained by adjusting the theoretical curve to the experiments. Excellent agreement between theory and experiment can be achieved.
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TL;DR: In this article, the one-dimensional electrothermal balance equation is solved for a thin sandwich of a semiconductor with field-independent conductivity between two highly conductive electrodes.
Abstract: The one-dimensional electro-thermal balance equation is solved for a thin sandwich of a semiconductor with field-independent conductivity between two highly conductive electrodes. Temperature- and field-profiles are calculated. It is shown that the current—voltage characteristics are monotonous (not S-shaped) and contain a branch parallel to the current axis. This branch may be identified with the holding branch of Ovonics in agreement with the experiment.
Die eindimensionale elektro-thermische Gleichgewichtsgleichung wird fur einen Schichtkondensator eines Halbleiters mit feldunabhangiger Leitfahigkeit zwischen zwei hochleitenden Elektroden gelost. Temperatur-und Feldprofile werden berechnet. Es wird gezeigt, das die Strom—Spannungs-Kennlinie monoton ist (nicht S-formig), und das sie einen Zweig parallel zur Stromachse enthalt. Dieser Zweig kann mit dem Haltezweig von Ovonics in Ubereinstimmung mit experimentellen Daten identifiziert werden.
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TL;DR: In this article, a small sieve-tray column operated in the cycling mode with alternate flow of vapor and liquid was used for desorbing ammonia from water by air.
Abstract: Tray efficiencies were measured for desorbing ammonia from water by air in a small sieve-tray column operated in the cycling mode, that is, with alternate flow of vapor and liquid. The actual efficiency improvement obtained was compared with that theoretically possible assuming the liquid flows without mixing when dropped. A mixing model was proposed and the mixing parameter evaluated from the experimental data.
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TL;DR: In this paper, the variations in a natural salt-marsh were evaluated for a three year period in the southwestern coast of the Delaware Estuary, and several mechanisms were postulated to explain the seasonal fluctuations in the phosphorus concentrations.
Abstract: Dissolved phosphorus concentrations, salinity, pH, and related physical parameters were used to evaluate the variations in a natural salt-marsh. Diel, tidal, lunar, and seasonal variations in phosphorus concentrations were evaluated for a three year period in a natural marsh, situated along the southwestern coast of the Delaware Estuary. Seasonal concentrations of dissolved phosphorus reached a maximum during the summer months (150 μg at .l-1) and a minimum during the winter months (10 μg at .l-1). An equation representing the relationship of the measured parameters to the dissolved phosphorus concentrations is presented. Several mechanisms are postulated to explain the seasonal fluctuations in the phosphorus concentrations.
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TL;DR: By photoselective excitation of pyrazine molecules randomly oriented in rigid glassy solvents, this paper confirmed an earlier assignment of the principal axes of the magnetic fine structure tensor.