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Showing papers by "University of California, San Diego published in 1986"


Journal ArticleDOI
TL;DR: In this paper, a natural generalization of the ARCH (Autoregressive Conditional Heteroskedastic) process introduced in 1982 to allow for past conditional variances in the current conditional variance equation is proposed.

17,555 citations


Book ChapterDOI
01 Jan 1986
TL;DR: This chapter proposes a theoretical framework structured around the notion of a set of active schemas, organized according to the particular action sequences of which they are a part, awaiting the appropriate set of conditions so that they can become selected to control action.
Abstract: Much effort has been made to understand the role of attention in perception; much less effort has been placed on the role attention plays in the control of action Our goal in this chapter is to account for the role of attention in action, both when performance is automatic and when it is under deliberate conscious control We propose a theoretical framework structured around the notion of a set of active schemas, organized according to the particular action sequences of which they are a part, awaiting the appropriate set of conditions so that they can become selected to control action The analysis is therefore centered around actions, primarily external actions, but the same principles apply to internal actions—actions that involve only the cognitive processing mechanisms One major emphasis in the study of attentional processes is the distinction between controlled and automatic processing of perceptual inputs (eg, Shiffrin & Schneider, 1977) Our work here can be seen as complementary to the distinction between controlled and automatic processes: we examine action rather than perception; we emphasize the situations in which deliberate, conscious control of activity is desired rather than those that are automatic

4,060 citations


Journal ArticleDOI
TL;DR: The TRACE model, described in detail elsewhere, deals with short segments of real speech, and suggests a mechanism for coping with the fact that the cues to the identity of phonemes vary as a function of context.

2,663 citations


Journal ArticleDOI
TL;DR: In this article, the authors discuss the current research in building models of conditional variances using the Autoregressive Conditional Heteroskedastic (ARCH) and Generalized ARCH (GARCH) formulations.
Abstract: This paper will discuss the current research in building models of conditional variances using the Autoregressive Conditional Heteroskedastic (ARCH) and Generalized ARCH (GARCH) formulations. The discussion will be motivated by a simple asset pricing theory which is particularly appropriate for examining futures contracts with risk averse agents. A new class of models defined to be integrated in variance is then introduced. This new class of models includes the variance analogue of a unit root in the mean as a special case. The models are argued to be both theoretically important for the asset pricing models and empirically relevant. The conditional density is then generalized from a normal to a Student-t with unknown degrees of freedom. By estimating the degrees of freedom, implications about the conditional kurtosis of these models and time aggregated models can be drawn. A further generalization allows the conditional variance to be a non-linear function of the squared innovations. Throughout empirical...

2,055 citations


Journal ArticleDOI
TL;DR: Etude des equations paraboliques du type (Δ−q/x,t)−∂/∂t)u(x, t)=0 sur une variete riemannienne generale as discussed by the authors.
Abstract: Etude des equations paraboliques du type (Δ−q/x,t)−∂/∂t)u(x,t)=0 sur une variete riemannienne generale. Introduction. Estimations de gradients. Inegalites de Harnack. Majorations et minorations des solutions fondamentales. Equation de la chaleur et noyau de Green. Operateur de Schrodinger

1,671 citations


Journal ArticleDOI
18 Dec 1986-Nature
TL;DR: The cDNA sequence of human c-erb-A indicates that the protein encoded by the gene is related to the steroid hormone receptors, and binding studies show it to be a receptor for thyroid hormones.
Abstract: The cDNA sequence of human c-erb-A, the cellular counterpart of the viral oncogene v-erb-A, indicates that the protein encoded by the gene is related to the steroid hormone receptors. Binding studies with the protein show it to be a receptor for thyroid hormones.

1,433 citations



Journal ArticleDOI
TL;DR: The brains of 12 AIDS patients were studied using in situ hybridization to identify human immunodeficiency virus nucleic acid sequences and immunocytochemistry to identify viral and cellular proteins, suggesting that CNS dysfunction is due to indirect effects rather than neuronal or glial infection.
Abstract: Dysfunction of the central nervous system (CNS) is a prominent feature of the acquired immune deficiency syndrome (AIDS). Many of these patients have a subacute encephalitis consistent with a viral infection of the CNS. We studied the brains of 12 AIDS patients using in situ hybridization to identify human immunodeficiency virus [HIV, referred to by others as human T-cell lymphotropic virus type III (HTLV-III), lymphadenopathy-associated virus (LAV), AIDS-associated retrovirus (ARV)] nucleic acid sequences and immunocytochemistry to identify viral and cellular proteins. Nine patients had significant HIV infection in the CNS. In all examined brains, the white matter was more severely involved than the grey matter. In most cases the infection was restricted to capillary endothelial cells, mononuclear inflammatory cells, and giant cells. In a single case with severe CNS involvement, a low-level infection was seen in some astrocytes and neurons. These results suggest that CNS dysfunction is due to indirect effects rather than neuronal or glial infection.

1,221 citations



Book
29 Apr 1986
TL;DR: The Bradford Book as mentioned in this paper provides a general introduction to neurophysiology, neuroanatomy, and neuropsychology, and a discussion of some of the most promising theoretical developments currently under exploration in functional neurobiology and in the connectionist models within artificial intelligence research.
Abstract: Five chapters in the book's first part, "Some Elementary Neuroscience," sketch the history of the science of nervous systems and provide a general introduction to neurophysiology, neuroanatomy, and neuropsychology. In the second part, "Recent Developments in the Philosophy of Science," chapters place the mind-body problem within the wider context of the philosophy of science. Drawing on recent research in this area, a general account of intertheoretic reduction is explained, arguments for a reductionist strategy are developed, and traditional objections from dualists and other anti reductionists are answered in novel ways. The third part, "A Neurophilosophical Perspective," concludes the book with a presentation and discussion of some of the most promising theoretical developments currently under exploration in functional neurobiology and in the connectionist models within artificial intelligence research. A Bradford Book.

954 citations


Journal ArticleDOI
TL;DR: In this article, a nonlinear relationship between electricity sales and temperature is estimated using a semiparametric regression procedure that easily allows linear transformations of the data and accommodates introduction of covariates, timing adjustments due to the actual billing schedules, and serial correlation.
Abstract: A nonlinear relationship between electricity sales and temperature is estimated using a semiparametric regression procedure that easily allows linear transformations of the data. This accommodates introduction of covariates, timing adjustments due to the actual billing schedules, and serial correlation. The procedure is an extension of smoothing splines with the smoothness parameter estimated from minimization of the generalized cross-validation criterion introduced by Craven and Wahba (1979). Estimates are presented for residential sales for four electric utilities and are compared with models that represent the weather using only heating and cooling degree days or with piecewise linear splines.

Journal ArticleDOI
29 Aug 1986-Cell
TL;DR: Characterization of 27 insertional mutants of the hGR allowed the location of at least four functional domains, two of which correspond to the predicted DNA- and steroid-binding domains, raising the possibility that other regions in the receptor are necessary for full transcriptional activation but are not specifically involved in steroid or DNA binding.

Book
01 Nov 1986
TL;DR: A comparison of the Knapsack as a Nonlinear Function and Nonlinear Combining Functions with Memory, and the Summation Principle, which helps clarify the role of memory in the generation of sequences.
Abstract: 1. Introduction.- 2. Stream Ciphers.- 2.1. Theoretical versus Practical Security.- 2.2. The Key Stream Generator.- 2.3. The Synchronization (Problem) of Stream Ciphers.- 3. Algebraic Tools.- 3.1. Finite Fields and Polynomials.- 3.2. Linear Feedback Shift Registers (LFSRs) and Sequences.- 3.3. Minimal Polynomial and Traces.- 4. Random Sequences and Linear Complexity.- 5. Nonlinear Theory of Periodic Sequences.- 5.1. Nonlinear Operations on Phases of a Sequence with Irreducible Minimal Polynomial.- 5.2. Nonlinear Operations on Sequences with Distinct Minimal Polynomials.- 5.3. Correlation-Immunity of Memoryless Combining Functions.- 5.4. Summary and Conclusions.- 6. Multiple Speed: An Additional Parameter in Secure Sequence Generation.- 6.1. The Simulated Linear Feedback Shift Register.- 6.2. A Random Number Generator Suggested by a Linear Cipher Problem.- 6.2.1. The Random Sequence Generator.- 6.2.2. Analysis of the Random Sequence Generator.- 6.2.3. Extensions and Comments.- 7. The Knapsack as a Nonlinear Function.- 7.1. The Significance of the Knapsack for Secrecy Systems.- 7.2. Addition is a Cryptographically Useful Function.- 7.3. The Knapsack in GF(2)-Arithmetic.- 8. The Hard Knapsack Stream Cipher.- 8.1. System Description.- 8.2. Analysis of the Knapsack Stream Cipher.- 8.3. Conclusions and Design Considerations.- 8.4. Simulation Results of Small Scale Knapsack Stream Ciphers.- 9. Nonlinear Combining Functions with Memory.- 9.1. Correlation Immunity.- 9.2. The Summation Principle.- 9.3. Summary and Conclusions.- Literature References.

Journal ArticleDOI
TL;DR: This approach uncovers the limitations of the Gutzwiller approximation and clarifies its connection to the "auxiliary-boson" mean- field theory of the Anderson model, leading to a novel strong-coupling mean-field theory which allows for a unified treatment of antiferromagnetism and ferromagnets, metal-to-insulator transition, and Kondo compensation effects.
Abstract: We propose a new functional integral representation of the Hubbarda and Anderson models of lattice fermions. The simplest saddle-point approximation leads, at zero temperature, to the results derived from the Gutzwiller variational wave function. This approach uncovers the limitations of the Gutzwiller approximation and clarifies its connection to the "auxiliary-boson" mean-field theory of the Anderson model. This formulation leads to a novel strong-coupling mean-field theory which allows for a unified treatment of antiferromagnetism and ferromagnetism, metal-to-insulator transition, and Kondo compensation effects.

Journal ArticleDOI
14 Nov 1986-Science
TL;DR: Although light was detected in most organs in intact, transgenic plants (leaves, stems, and roots), the pattern of luminescence appeared to reflect both the organ-specific distribution of Luciferase and the pathway for uptake of luciferin through the vasculature of the plant.
Abstract: The luciferase gene from the firefly, Photinus pyralis, was used as a reporter of gene expression by light production in transfected plant cells and transgenic plants. A complementary DNA clone of the firefly luciferase gene under the control of a plant virus promoter (cauliflower mosaic virus 35S RNA promoter) was introduced into plant protoplast cells (Daucus carota) by electroporation and into plants (Nicotiana tabacum) by use of the Agrobacterium tumefaciens tumor-inducing plasmid. Extracts from electroporated cells (24 hours after the introduction of DNA) and from transgenic plants produce light when mixed with the substrates luciferin and adenosine triphosphate. Light produced by the action of luciferase was also detected in undisrupted leaves or cells in culture from transgenic plants incubated in luciferin and in whole transgenic plants "watered" with luciferin. Although light was detected in most organs in intact, transgenic plants (leaves, stems, and roots), the pattern of luminescence appeared to reflect both the organ-specific distribution of luciferase and the pathway for uptake of luciferin through the vasculature of the plant.

Journal ArticleDOI
TL;DR: In this paper, a new laminated composite plate theory was developed based upon a new variational principle proposed by Reissner (1984), which was achieved by including a zigzag-shaped C 0 function to approximate the thickness variation of in-plane displacements.
Abstract: In order to improve the accuracy of the in-plane response of the shear, deformable laminated composite plate theory, a new laminated plate theory has been developed based upon a new variational principle proposed by Reissner (1984). The improvement is achieved by including a zigzag-shaped C 0 function to approximate the thickness variation of in-plane displacements. The accuracy of this theory is examined by applying it to a problem of cylindrical bending of laminated plates which has been solved exactly by Pagano (1969). The comparison of the in-plane response with the exact solutions for symmetric three-ply and five-ply layers has demonstrated that the new theory predicts the in-plane response very accurately even for small span-to-depth ratios.

Journal ArticleDOI
TL;DR: It is argued that technical theories must be considered in the context of the uses to which they are put and help the theorist to determine what is a good approximation, the degree of formalization that is justified, the appropriate commingling of qualitative and quantitative techniques, and encourages cumulative progress through the heuristic of divide and conquer.
Abstract: There is growing interest in the use of sound to convey information in computer interfaces. The strategies employed thus far have been based on an understanding of sound that leads to either an arbitrary or metaphorical relation between the sounds used and the data to be represented. In this article, an alternative approach to the use of sound in computer interfaces is outlined, one that emphasizes the role of sound in conveying information about the world to the listener. According to this approach, auditory icons, caricatures of naturally occurring sounds, could be used to provide information about sources of data. Auditory icons provide a natural way to represent dimensional data as well as conceptual objects in a computer system. They allow categorization of data into distinct families, using a single sound. Perhaps the most important advantage of this strategy is that it is based on the way people listen to the world in their everyday lives.

Journal ArticleDOI
TL;DR: A Monte Carlo algorithm to study properties of dilute magnetic alloys can treat a small number of magnetic impurities interacting wiith the conduction electrons in a metal, showing the expected universal behavior at low temperatures.
Abstract: The paper discusses a Monte Carlo algorithm to study properties of dilute magnetic alloys; the method can treat a small number of magnetic impurities interacting wiith the conduction electrons in a metal. Results for the susceptibility of a single Anderson impurity in the symmetric case show the expected universal behavior at low temperatures. Some results for two Anderson impurities are also discussed.

Journal ArticleDOI
TL;DR: In this paper, the effect of prolonged postmortem freezing storage (between 1 1/2 and 3 months at -20 degrees C) on the structural properties of the medial collateral ligament (MCL)-bone complex as well as the mechanical properties of MCL substance from the rabbit knee was examined.


Journal ArticleDOI
TL;DR: A method is presented to describe the geometry of the opened-up stress-free state of the artery, which is taken to be the reference state, and an algorithm is outlined for the identification of the stress-strain relationship of the arterial wall.
Abstract: In the study of vascular elasticity the unloaded state (one with zero transmural pressure and zero axial load) is commonly used as the reference state in which stresses and strains are considered as zero everywhere. Strains at loaded states are defined with respect to this state. Stress-strain relationships are identified under the assumption that the vessel wall is stress-free at this unloaded state. Evidence of the existence of residual stresses in the arterial wall at the unloaded state is given in Fung [4]. With a longitudinal cut along the vessel wall the unloaded specimen springs open and its cross section becomes a sector. The opening angle of the vessel wall is time-dependent after the sudden relief of the initial residual stress. It shows that the artery is not stress-free at the unloaded state. It is important to identify the stress-free state. When we use pseudoelasticity [3] to characterize the arterial wall, we need a stress-free state as the reference state for strain measurements. Correspondingly, we also want to define stress with respect to this same reference state so that we can relate stresses to strains easily. Presence of the residual stress at the unloaded tube state will certainly affect the evaluation of stress distribution in the arterial wall due to actual loadings in the physiological range. In this note we present a method to describe the geometry of the opened-up stress-free state of the artery, which is taken to be the reference state. An algorithm is outlined for the identification of the stress-strain relationship of the arterial wall. Residual stresses, and strains in the unloaded tube are evaluated. With the consideration of residual stresses the stress distributions due to loadings in the physiological range are also evaluated.

Journal ArticleDOI
TL;DR: The most recent status of immuno‐cryoultramicrotomy is reviewed and the technical aspects of each step of the method are analysed in detail to provide a useful source of information for investigators using this method.
Abstract: This paper reviews the most recent status of immuno-cryoultramicrotomy. The technical aspects of each step of the method are also analysed in detail with the intention of providing a useful source of information for investigators using this method.

Journal ArticleDOI
TL;DR: Comparative studies have demonstrated that, in vivo, the enzyme exhibits a preference for one basic residue C-terminal to the phosphorylatable residue, as in the sequence: Ser/Thr-Xaa-Lys/Arg, where Xaa is usually an uncharged residue.
Abstract: Although the Ca2+/phospholipid-dependent protein kinase, protein kinase C, has a broad substrate specificity in vitro, the enzyme appears considerably less promiscuous in vivo. To date only a handful of proteins have been identified as physiological substrates for this protein kinase. In order to determine the basis for this selectivity for substrates in intact cells, we have probed the subsrate primary sequence requirements of protein kinase C using synthetic peptides corresponding to sites of phosphorylation from four of the known physiological substrates. We have also identified the acetylated N-terminal serine of chick muscle lactate dehydrogenase as an in vitro, site of phosphyorylation for this protein kinase. These comparative studies have demonstrated that, in vivo, the enzyme exhibits a preference for one basic residue C-terminal to the phosphorylatable residue, as in the sequence: Ser/Thr-Xaa-Lys/Arg, where Xaa is usually an uncharged residue. Additional basic residues, both N and C-terminal to the target amino acid, enhance the Vmax and Km parameters of phosphorylation. None of the peptides based on physiological phosphrylation sites of protein kinase C was an efficient substrate of cAMP-dependent protein kinase, emphasizing the distinct site-recognition selectivities of these two pleiotropic protein kinases. The favorable kinetic parameters of several of the synthetic peptides, coupled with their selectivity for phosphorylation by protein kinase C, will facilitate the assay of this enzyme in the presence of other protein kinases in tissue and cell extracts.

Journal ArticleDOI
TL;DR: Transport, thermal, and magnetic data for the heavy electron system URu2Si2 indicate that a charge- or spin-density-wave transition opens an energy gap over a portion of the Fermi surface below T0roughly-equal17.5 K and demonstrate that bulk superconductivity occurs below T/sub c/roughly
Abstract: Transport, thermal, and magnetic data for the heavy electron system ${\mathrm{URu}}_{2}$${\mathrm{Si}}_{2}$ indicate that a charge- or spin-density-wave transition opens an energy gap of \ensuremath{\sim}11 meV over a portion of the Fermi surface below ${\mathrm{T}}_{0}$\ensuremath{\approxeq}17.5 K and demonstrate that bulk superconductivity occurs below ${\mathrm{T}}_{\mathrm{c}}$\ensuremath{\approxeq}1.5 K. The pressure dependences of ${\mathrm{T}}_{0}$ and ${\mathrm{T}}_{\mathrm{c}}$ support this interpretation. The unusually large initial slope of the upper critical magnetic field (9.2 T/K) is consistent with the high values of the electronic-specific-heat coefficient and the electrical resistivity.

Journal ArticleDOI
TL;DR: Data suggest that when PT is placed in the anatomic and environmental milieu of the ACL, a “ligamentization” of the grafted tissue results; also the autograft initially depends on synovial fluid nutrition, as revascularization occurs after 6 weeks.

Journal ArticleDOI
TL;DR: Developmental norms by age for the Wisconsin Card Sorting Test are presented to complement and extend existing adult norms for theWCST and to facilitate the clinical use of the WCST as a neuropsychological test in child populations.
Abstract: While the Wisconsin Card Sorting Test (WCST) has been used widely among adult populations to evaluate the effects of frontal-lobe lesions, no comparable work has been done among younger populations due, in part, to the lack of an adequate normative base. This study presents developmental norms by age for the WCST for 105 school-age children. The data indicate that, by the time children are 10 years old, their performance on the WCST is indistinguishable from that of normal adults. Examination of the acquisition curves by age for Categories Achieved, Perseverative Errors, and Failures to Maintain Set reveals developmental changes that roughly correspond with neuroanatomical changes in the brain and cognitive stages of development. The present developmental norms are intended to complement and extend existing adult norms for the WCST and to facilitate the clinical use of the WCST as a neuropsychological test in child populations.

Journal Article
TL;DR: Data from these studies is discussed in relation to the reported potencies of these antagonists in blocking alpha 1-receptor-mediated responses which may correlate with the designation of alpha 1A or alpha 1B binding sites.
Abstract: [3H]Prazosin and [3H]WB4101 [2-(2,6-dimethoxyphenoxyethyl)aminomethyl-1,4 benzodioxane] have both been proposed to label alpha 1-adrenergic receptors in the rat central nervous system. As many discrepancies between the binding of these two ligands have arisen, we conducted these studies in order to reevaluate their binding characteristics and resolve the similarities and differences in the pharmacological characteristics of their respective binding sites. [3H]Prazosin binding is characterized by a monophasic saturation isotherm. Prazosin, indoramine, and dihydroergocryptine competitions with [3H]prazosin are steep and monophasic, and model best to a single binding site. In contrast, phentolamine and WB4101 competition curves are shallow in rat cortex, exhibiting Hill coefficients significantly less than 1.0, and model to two binding sites of approximately equal proportions. The higher and lower affinity components are defined as alpha 1A and alpha 1B, respectively. [3H]WB4101 also labels two binding sites in rat cortex and hippocampus with picomolar and nanomolar affinity, respectively. However, the nanomolar binding site is serotonergic and not adrenergic. The picomolar site (KD = 150 pm) has characteristics of an alpha 1-receptor binding site: prazosin, WB4101, and phentolamine affinities for this [3H]WB4101 binding site correlate with their affinities for the highest affinity component (alpha 1A) of [3H]prazosin binding. In addition, the Bmax of this [3H] WB4101-labeled site is equal to one-half of the total [3H]prazosin Bmax. Agonist competitions with [3H]prazosin binding are multiphasic with pseudo-Hill slopes less than 1.0 and with a rank order of affinity of epinephrine greater than norepinephrine greater than phenylephrine. When binding to the alpha 1A component is blocked by a 30 nM phentolamine mask, the same rank order of agonist affinities is preserved. Although the affinities of epinephrine and norepinephrine at the two subtypes are identical, phenylephrine is weaker at the alpha 1B site. The ratio of the potency of phentolamine versus prazosin is about 4 at the alpha 1A component but about 80 at the alpha 1B binding site. We discuss these data in relation to the reported potencies of these antagonists in blocking alpha 1-receptor-mediated responses which may correlate with our designation of alpha 1A or alpha 1B binding sites.

Journal ArticleDOI
TL;DR: The phenomenon of preserved priming effects in amnesia is reviewed, relationships between priming and other memory functions are described, and what this spared memory function tells us about the organization of memory is commented on.
Abstract: Amnesic patients are impaired on tests of recall and recognition memory, yet they exhibit intact priming effects. That is, their performance can be facilitated or biased by recently encountered information. This paper reviews the phenomenon of preserved priming effects in amnesia, describes relationships between priming and other memory functions, and comments on what this spared memory function tells us about the organization of memory.

Journal ArticleDOI
TL;DR: This paper found that within 250 ms of the presentation of a congruous word and within 450 ms of an incongruous word, a significant portion of the brain processes which determine whether a word will or will not be recognized some time in the future have taken place.

Journal ArticleDOI
01 Jan 1986-Nature
TL;DR: The complete amino-acid sequence of an acetylcholinesterase inferred from the sequence of a complementary DNA clone is reported and the 575-residue protein shows significant homology with the C-terminal portion of thyroglobulin8.
Abstract: Acetylcholinesterase, an essential enzyme of the nervous system, rapidly terminates the action of acetylcholine released into the synapse. Acetylcholinesterase is also found (in lower abundance) in extrajunctional areas of muscle and nerve and on erythrocyte membranes. Hydrodynamic analyses of the native enzyme and characterization of its dissociated subunits have revealed multiple enzyme forms which can be divided into two classes: dimensionally asymmetric forms which are usually found within the synapse and contain a collagen-like structural subunit disulphide-linked to the catalytic subunits; and globular forms which appear to be widely distributed on the outer surface of cell membranes. Both forms have been characterized in the ray Torpedo californica and, although their catalytic behaviours seem to be identical, they differ slightly in amino-acid composition, peptide maps and reactivity with certain monoclonal antibodies. Here, we report the complete amino-acid sequence of an acetylcholinesterase inferred from the sequence of a complementary DNA clone. The 575-residue protein shows significant homology with the C-terminal portion of thyroglobulin.