Showing papers by "University of California, Santa Barbara published in 1984"
TL;DR: The cold dark matter hypothesis as mentioned in this paper suggests that the dark matter that appears to be gravitationally dominant on all scales larger than galactic cores may consist of axions, stable photinos, or other collisionless particles whose velocity dispersion in the early Universe is so small that fluctuations of galactic size or larger are not damped by free streaming.
Abstract: The dark matter that appears to be gravitationally dominant on all scales larger than galactic cores may consist of axions, stable photinos, or other collisionless particles whose velocity dispersion in the early Universe is so small that fluctuations of galactic size or larger are not damped by free streaming. An attractive feature of this cold dark matter hypothesis is its considerable predictive power: the post-recombination fluctuation spectrum is calculable, and it in turn governs the formation of galaxies and clusters. Good agreement with the data is obtained for a Zeldovich (|δk|2 ∝ k) spectrum of primordial fluctuations.
1,448 citations
TL;DR: In this article, it was shown that non-Abelian gauge fields arise in the adiabatic development of simple quantum mechanical systems and are related to energy splittings, which may be observable in real systems.
Abstract: Generalizing a construction of Berry and Simon, we show that non-Abelian gauge fields arise in the adiabatic development of simple quantum mechanical systems. Characteristics of the gauge fields are related to energy splittings, which may be observable in real systems. Similar phenomena are found for suitable classical systems.
1,432 citations
TL;DR: In this article, it was shown that if rich clusters formed where the primordial density enhancement, when averaged over an appropriate volume, was unusually large, then they give a biased measure of the large-scale density correlation function determiend by the probability distribution of the density fluctuations on a rich cluster mass scale.
Abstract: If rich clusters formed where the primordial density enhancement, when averaged over an appropriate volume, was unusually large, then they give a biased measure of the large-scale density correlation function determiend by the probability distribution of the density fluctuations on a rich cluster mass scale. If this distribution was Gaussian, the correlation function is amplified. The amplification for rich clusters is estimated to be eaual about ten and predicted trend of amplification with richness agrees qualitatively with that observed. Some implications of these results for the large-scale density correlations are discussed.
1,220 citations
TL;DR: The zero-temperature equation of state of metals, in the absence of phase transitions, was shown to be accurately predicted from zero-pressure data in this article, and a simple universal relation was found.
Abstract: The zero-temperature equation of state of metals, in the absence of phase transitions, is shown to be accurately predicted from zero-pressure data. Upon appropriate scaling of experimental pressure-volume data a simple universal relation is found. These results provide further experimental confirmation of the recent observation that the total-binding-energy---versus---separation relations for metals obey a universal scaling relation. Important to our results is a parameter $\ensuremath{\eta}$, which is a measure of the anharmonicity of a crystal. This parameter is shown to be essential in predicting the equation of state. A simple formula is given which predicts the zero-temperature derivative of the bulk modulus with respect to pressure.
1,208 citations
TL;DR: In this article, the Weinberg-Salam solution of the classical field equations is given, where the weak mixing angle is considered to be small and the energy increases from 8 TeV to 14 TeV as the Higgs coupling.
Abstract: We give a close approximation to a static, but unstable, solution of the classical field equations of the Weinberg-Salam theory, where the weak mixing angle ${\ensuremath{\Theta}}_{w}$ is considered to be small. Its energy increases from \ensuremath{\sim}8 TeV to \ensuremath{\sim}14 TeV as the Higgs coupling $\ensuremath{\lambda}$ runs from $0 \mathrm{to} \ensuremath{\infty}$. Furthermore, it has a large magnetic dipole moment and its baryonic (and leptonic) charge is \textonehalf{}. The possible physical relevance of this solution is discussed.
1,026 citations
TL;DR: In this paper, the phase transition restoring chiral symmetry at finite temperatures is considered in a linear σ-sigma model. But the model is not suitable for the case of massless flavors.
Abstract: The phase transition restoring chiral symmetry at finite temperatures is considered in a linear $\ensuremath{\sigma}$ model. For three or more massless flavors, the perturbative $\ensuremath{\epsilon}$ expansion predicts the phase transition is of first order. At high temperatures, the ${\mathrm{U}}_{A}(1)$ symmetry will also be effectively restored.
897 citations
TL;DR: In this paper, the statistics of quasiparticles entering the quantum Hall effect were deduced from the adiabatic theorem, and these excitations were found to obey fractional statistics, a result closely related to their fractional charge.
Abstract: The statistics of quasiparticles entering the quantum Hall effect are deduced from the adiabatic theorem. These excitations are found to obey fractional statistics, a result closely related to their fractional charge.
835 citations
TL;DR: The relationship between the actual charge and the renormalized charge by solving the Boltzmann-Poisson equation numerically in a spherical Wigner-Seitz cell was analyzed in this article.
Abstract: The interactions between charged colloidal particles with sufficient strength to cause crystallization are shown to be describable in terms of the usual Debye–Huckel approximation, but with a renormalized charge. The effective charge in general is smaller than the actual charge. We calculate the relationship between the actual charge and the renormalized charge by solving the Boltzmann–Poisson equation numerically in a spherical Wigner–Seitz cell. We then relate the numerical solutions and the effective charge to the osmotic pressure and the bulk modulus of the crystal. Our calculations also reveal that the renormalization of the added electrolyte concentration is negligible, so that the effective charge computations are useful even in the presence of salts.
827 citations
TL;DR: In this article, the ground-state density n of a many-electron system obeys a Schroedinger-like differential equation which may be solved by standard Kohn-Sham programs.
Abstract: The present investigation is concerned with relations studied by Hohenberg and Kohn (1964) and Kohn and Sham (1965). The properties of a ground-state many-electron system are determined by the electron density. The correct differential equation for the density, as dictated by density-functional theory, is presented. It is found that the ground-state density n of a many-electron system obeys a Schroedinger-like differential equation which may be solved by standard Kohn-Sham programs. Results are connected to the traditional exact Kohn-Sham theory. It is pointed out that the results of the current investigations are readily extended to spin-density functional theory.
721 citations
TL;DR: In this article, the fractal dimension of colloidal aggregates of small silica particles is measured by both light and x-ray scattering, showing that the aggregates are fractal.
Abstract: Measurement of the fractal dimension, $D$, of colloidal aggregates of small silica particles is reported. We observe power-law decay of the structure factor $[S(k)\ensuremath{\sim}{k}^{\ensuremath{-}D}]$ by both light and x-ray scattering showing that the aggregates are fractal. $D$ is found to be 2.12\ifmmode\pm\else\textpm\fi{}0.05, which is intermediate between recent numerical results for the kinetic models of diffusion-limited aggregation ($D=2.5$) and cluster aggregation ($D=1.75$), but is rather close to the value for lattice animals ($D=2.0$), which are equilibrium structures.
637 citations
TL;DR: The hypothesis that separate neural systems mediate the reinforcing properties of opioid and psychomotor stimulant drugs was tested by examining the role of mesolimbic dopamine neurons in maintaining intravenous heroin and cocaine self-administration and data support the hypothesis that independent neural subtrates are responsible for the reinforcing actions of these two drugs.
Abstract: The hypothesis that separate neural systems mediate the reinforcing properties of opioid and psychomotor stimulant drugs was tested by examining the role of mesolimbic dopamine (DA) neurons in maintaining intravenous heroin and cocaine self-administration. After local destruction of the DA terminals in the nucleus accumbens (NAcc) with 6-hydroxydopamine (6-OHDA), rats trained to self-administer cocaine and heroin on alternate days were observed for changes in their drug-seeking behaviors. Postlesion responding for cocaine showed a time-dependent decrease or extinction, whereas heroin self-administration showed a time-dependent recovery. By the fifth trial postlesion, heroin self-administration had recovered to 76% of prelesion baseline levels, but cocaine self-administration had dropped to 30% of prelesion baseline rates. Thus, selective lesions of the DA terminals in the nucleus accumbens significantly attenuate cocaine but not heroin self-administration. These data support the hypothesis that independent neural substrates are responsible for the reinforcing actions of these two drugs.
TL;DR: In this paper, the physical processes occuring when solid surfaces are used to modify, in a substantial way, the spectroscopic properties of molecules located nearby are reviewed, which is achieved by enhancement of the local laser field, increase in molecular emission, and decrease in excited state lifetime.
TL;DR: In this paper, it was shown that the angular momentum of galaxies grows to first order (in proportion to t) during the linear phases of protogalactic evolution, and this result is confirmed in N-body simulations of the formation of structure.
Abstract: An analysis by Doroshkevich (1970) which shows that the angular momentum of galaxies grew to first order (in proportion to t) during the linear phases of protogalactic evolution is expanded. This result is confirmed in N-body simulations of the formation of structure. The well-known study of Peebles (1969) found growth at second order only (in proportion to t to the 5/3-power) because its analysis was restricted to spherical regions. In such regions growth occurs purely as a result of convective effects on the bounding surface; the material initially within a spherical volume gains no angular momentum in second-order perturbation theory. These considerations do not affect estimates of the total angular momentum acquired by a galaxy in the gravitational instability picture.
TL;DR: In this paper, the authors present a new method of electrochemical polymerization of poly(thiophene) using dithiophene as the starting material, from which they obtain a high-quality film with a sharp interband absorption edge.
Abstract: We present a new method of electrochemical polymerization of poly(thiophene) using dithiophene as the starting material, from which we obtain a high-quality film with a sharp interband absorption edge. An in situ study of the absorption spectrum during the electrochemical doping process has been carried out. In the dilute regime, the results are in detailed agreement with charge storage via bipolarons; weakly confined soliton pairs with confinement parameter $\ensuremath{\gamma}\ensuremath{\cong}0.1\ensuremath{-}0.2$. At the highest doping levels, the data are characteristic of the free-carrier absorption expected for a metal. From a parallel electrochemical voltage spectroscopy study, we find evidence of charge injection near the band edge and charge removal from the bipolaron gap states. In the dilute regime, the position of the chemical potential is consistent with charge storage in weakly confined bipolarons. The high Coulombic recovery over a charge-discharge cycle indicates that poly (thiophene) may be an excellent cathode-active material in battery applications.
TL;DR: In this paper, the universal relation between critical exponents and the amplitude of the correlation length divergence as a function of finite size at the critical point of two-dimensional systems is shown to be a consequence of conformal invariance.
Abstract: The universal relation between critical exponents and the amplitude of the correlation length divergence as a function of finite size at the critical point of two-dimensional systems is shown to be a consequence of conformal invariance. Both periodic and free boundary conditions are considered.
TL;DR: A functional analysis of communicative behaviors indicated that, despite a wide variation in communicative means, the autistic subjects displayed a relatively homogeneous profile of communative functions that was both quantitatively and qualitatively different from the normal profile.
Abstract: The purpose of this study was to examine profiles of communicative and cognitive-social abilities in a small group of autistic children functioning in the prelinguistic and early stages of language...
TL;DR: In this article, a cascade of two sections is proposed for finite impulse response (FIR) digital filters, where the first section generates a sparse set of impulse response samples and the other section generates the remaining samples by using interpolation.
Abstract: A new approach to implement computationally efficient finite impulse response (FIR) digital filters is presented. The filter structure is a cascade of two sections. The first section generates a sparse set of impulse response samples and the other section generates the remaining samples by using interpolation. The method can be used to implement most practical FIR filters with significant savings in the number of arithmetic operations. Typically 1/2 to 1/8 of the number of multipliers and adders of conventional FIR filters are required in the implementation. The saving is achieved both in the linear phase and the non-linear phase cases. In addition, the new implementation gives smaller coefficient sensitivities and better roundoff noise properties than conventional implementations.
TL;DR: In this article, it was shown that cosmic strings would generate anisotropy of the microwave background temperature with a very distinctive feature; the temperature would have steplike discontinuities on curves on the sky.
Abstract: There has been much interest in the cosmological consequences of line-like topological defects (‘cosmic strings’) which may be produced in a phase transition in the early Universe1–8. Such strings would produce density fluctuations on a broad range of scales and may have been responsible for the formation of galaxies. In view of this possibility, it would be useful to have more direct evidence of the existence of strings than the observed clustering of matter. We show here that cosmic strings would generate anisotropy of the microwave background temperature with a very distinctive feature; the temperature would have steplike discontinuities on curves on the sky. Present anisotropy measurements limit the line density parameter, Gμ to be <10−5. Popular values of this parameter, for the purpose of galaxy formation, are only an order of magnitude below this. The anisotropy that we discuss will exist in addition to that produced by curvature fluctuations due to strings and matter at the time that the Universe becomes optically thin.
TL;DR: In this article, a study of geometric properties of convex sets in topological vector spaces (which are always assumed to be separated) is presented, which are closely related to fixed point theorems.
Abstract: This paper is a study of certain geometric properties of convex sets in topological vector spaces (which are always assumed to be separated). These properties are closely related to fixed point theorems. While Theorems 7, 9, and 10 are explicitly fixed point or coincidence theorems for non-compact convex sets, Theorem 8 includes Theorem 9 (a coincidence theorem) as a special case. Theorems 1, 2, and 3 may be called "matching theorems", as the conclusions in these theorems assert the existence of a certain "matching". Consider for example, the conclusion of Theorem 3: "then there exists a non-empty finite subset {xl, x2 . . . . , x,} of X such that the convex hull of {x~, xz ..... x,} contains a point of the corresponding intersection (~ A(xi)". Notice that when n = 1, this becomes i=1 x~eA(x 0, a fixed point. The property required of the finite subset {Xl, x2 . . . . . x,} is a "matching" property involving two intuitively opposite conditions: a larger subset {xl, x2 . . . . . x,} of X would make its convex hull larger (and thus make it easier to have the required property), but would make the corresponding intersection
TL;DR: In this article, the mass and couplings of the invisible axion are derived, followed by suggestions for experiments to detect axions via the macroscopic forces they mediate.
Abstract: The forces mediated by spin-0 bosons are described, along with the existing experimental limits. The mass and couplings of the invisible axion are derived, followed by suggestions for experiments to detect axions via the macroscopic forces they mediate. In particular, novel tests of the T-violating axion monopole-dipole forces are proposed.
TL;DR: Good quantitative agreement was found when the microspectrophoto-metrically measured absorbance spectra were used to predict the behavioural sensitivity of individual animals to long wavelengths and suggests that the behavioural variation arises from variation in the retinal photopigments.
Abstract: The squirrel monkey (Saimiri sciureus) exhibits a polymorphism of colour vision: some animals are dichromatic, some trichromatic, and within each of these classes there are subtypes that resemble the protan and deutan variants of human colour vision. For each of ten individual monkeys we have obtained (i) behavioural measurements of colour vision and (ii) microspectrophotometric measurements of retinal photopigments. The behavioural tests, carried out in Santa Barbara, included wavelength discrimination, Rayleigh matches, and increment sensitivity at 540 and 640 nm. The microspectrophotometric measurements were made in London, using samples of fresh retinal tissue and a modified Liebman microspectrophotometer: the absorbance spectra for single retinal cells were obtained by passing a monochromatic measuring beam through the outer segments of individual rods and cones. The two types of data, behavioural and microspectrophotometric, were obtained independently and were handed to a third party before being interchanged between experimenters. From all ten animals, a rod pigment was recorded with $\lambda \_{\max}$ (wavelength of peak absorbance) close to 500 nm. In several animals, receptors were found that contained a short-wave pigment (mean $\lambda \_{\max}$ = 433.5 nm): these violet-sensitive receptors were rare, as in man and other primate species. In the middle- to long-wave part of the spectrum, there appear to be at least three possible Saimiri photopigments (with $\lambda \_{\max}$ values at about 537, 550 and 565 nm) and individual animals draw either one or two pigments from this set, giving dichromatic or trichromatic colour vision. Thus, those animals that behaviourally resembled human protanopes exhibited only one pigment in the red--green range, with $\lambda \_{\max}$ = 537 nm; other behaviourally dichromatic animals had single pigments lying at longer wavelengths and these were the animals that behaviourally had higher sensitivity to long wavelengths. Four of the monkeys were behaviourally judged to be trichromatic. None of the latter animals exhibited the two widely separated pigments (close to 535 and 567 nm) that are found in the middle- and long-wave cones of macaque monkeys. But the spread of $\lambda \_{\max}$ values for individual cones was greater in the trichromatic squirrel monkeys than in the dichromats; than in the case of three, behaviourally deuteranomalous, trichromats there was clear evidence that the distribution of $\lambda \_{\max}$ values was bimodal, suggesting photopigments at approximately 552 and 565 nm. The fourth, behaviourally protanomalous, trichromat exhibited a spread of individual $\lambda _{\max}$ values that ranged between 530 and 550 nm. Good quantitative agreement was found when the microspectrophotometrically measured absorbance spectra were used to predict the behavioural sensitivity of individual animals to long wavelengths. The concordance of the two sets of measurements places beyond question the existence of a polymorphism of colour vision in Saimiri sciureus and suggests that the behavioural variation arises from variation in the retinal photopigments. Heterozygous advantage may explain the polymorphism.
TL;DR: This paper examined the dynamics of partisanship and voting behavior by utilizing national survey panel data gathered in 1965, 1973, and 1982 from two strategically situated generations (members of the high school senior class of 1965 and their parents).
Abstract: The present study examines the dynamics of partisanship and voting behavior by utilizing national survey panel data gathered in 1965, 1973, and 1982 from two strategically situated generations—members of the high school senior class of 1965 and their parents. At the aggregate level, generational effects appeared in the persistently weaker partisan attachments of the younger generation. At the individual level, strong effects based on experience and habituation appeared in the remarkable gains occurring in the stability of partisan and other orientations among the young as they aged from their mid-20s to their mid-30s. Dynamic modeling of the relationship between partisanship and voting choice demonstrated that the younger voters had stabilized at an overall weaker level of partisanship, leading to more volatile voting behavior which, in turn, failed to provide the consistent reinforcement needed to intensify preexisting partisan leanings.
TL;DR: A plot of spin rate-versus-orientation for Hyperion at the pericenter of its orbit has revealed a large, chaotic zone surrounding Hyperion's synchronous spin-orbit state as mentioned in this paper.
TL;DR: This article explored three kinds of aids to text comprehension: aids for selecting information, such as behavioral objectives, or underlining; aids for building internal connections, e.g., outline headings or structured notetaking; and aids for constructing external connections such as concrete advance organizers or elaboration activities.
Abstract: This article explores three kinds of aids to text comprehension: aids for selecting information, such as behavioral objectives, or underlining; aids for building internal connections, such as outline headings or structured notetaking; aids for building external connections, such as concrete advance organizers or elaboration activities. Progress in understanding and using aids‐to‐text‐comprehension can be made by determining how various aids affect the internal cognitive processing of text information during reading.
TL;DR: Crustose red algae induce substratum-specific settlement, attachment and metamorphosis of the planktonic larvae of Haliotis rufescens Swainson, upon direct contact by the larvae with any of a number of algal species tested.
TL;DR: A large number of start mutations are isolated which confer on S. cerevisiae cells a conditional inability to complete start, presumably because they define genes which must be expressed for the start event to be successfully completed.
Abstract: In the budding yeast, Saccharomyces cerevisiae, division is controlled in response to nutrient limitation and in preparation for conjugation. Cells deprived of an essential nutrient or responding to mating pheromones cease division and become synchronous in the G1 interval, apparently constrained from completing a critical event. This event has been given the operational designation of 'start'. We have isolated a large number of start mutations which confer on S. cerevisiae cells a conditional inability to complete start (Fig. 1) presumably because they define genes which must be expressed for the start event to be successfully completed. We have described the isolation on plasmids of one of the start genes, CDC28, by genetic complementation and initial characterization of its product. We now describe the DNA sequence of the gene CDC28.
TL;DR: In this article, the synthesis and physical properties of poly(thiophene) with a molecular weight of approximately 4000 consisting of 46-47 thiophene rings (184- 188 carbons along the backbone).
TL;DR: In this article, it was shown that the predicted number of low-energy cosmic-ray antiprotons is comparable to the observed flux of cosmic rays and gamma rays in the galactic halo and that the cosmological photino density and the masses of scalar quarks and leptons determined the present annihilation rate.
Abstract: Observational tests of the hypothesis that the universe is flat and dominated by dark matter in the form of massive photinos include the production of significant fluxes of cosmic rays and gamma rays in our galactic halo. Specification of the cosmological photino density and the masses of scalar quarks and leptons determines the present annihilation rate. The predicted number of low-energy cosmic-ray antiprotons is comparable to the observed flux.
TL;DR: When there are many flavors of massless fermions, both three-dimensional electrodynamics, and a supersymmetric variant thereof, each spontaneously break chiral symmetry.
Abstract: When there are many flavors of massless fermions, both three-dimensional electrodynamics, and a supersymmetric variant thereof, each spontaneously break chiral symmetry. For the latter, this occurs without breaking supersymmetry, and without a photino condensate.