Showing papers by "University of Texas at Austin published in 1987"
TL;DR: A simple, effective measure of synonymous codon usage bias, the Codon Adaptation Index, is detailed, useful for predicting the level of expression of a gene, for assessing the adaptation of viral genes to their hosts, and for making comparisons ofCodon usage in different organisms.
Abstract: A simple, effective measure of synonymous codon usage bias, the Codon Adaptation Index, is detailed. The index uses a reference set of highly expressed genes from a species to assess the relative merits of each codon, and a score for a gene is calculated from the frequency of use of all codons in that gene. The index assesses the extent to which selection has been effective in moulding the pattern of codon usage. In that respect it is useful for predicting the level of expression of a gene, for assessing the adaptation of viral genes to their hosts, and for making comparisons of codon usage in different organisms. The index may also give an approximate indication of the likely success of heterologous gene expression.
3,196 citations
TL;DR: The role of beliefs in the practice of teaching is discussed in this article, where the authors focus on the role of belief in the teaching process in the context of a curriculum and its content.
Abstract: (1987). The role of beliefs in the practice of teaching. Journal of Curriculum Studies: Vol. 19, No. 4, pp. 317-328.
2,329 citations
TL;DR: In this article, the authors present a study of identity construction and avowal among homeless street people, with two underlying and interconected objectives in mind: to advance understanding of the manner in wich individuals at the bottom of status systems attempt to generate identities that provide them with a measures of self-worth and dignity and to shed additional empirical and theoretical light on the relationships among role, identity, and self-concept.
Abstract: This paper elaborates processes of identity construction and avowal among homeless street people, with two underlying and interconected objectives in mind: to advance understanding of the manner in wich individuals at the bottom of status systems attempt to generate identities that provide them with a measures of self-worth and dignity and to shed additional empirical and theoretical light on the relationships among role, identity, and self-concept. The data are from an ethnographic field study of homeless street people. "Identity talk" constitutes the primary form of "identity work" by means of which homeless street people construct and negotiate personal identities. Theree generic patterns of identity talk are alborated and illustrated: distancing, embracement, and fictive storytelling. Each form contains several subtypes that vary in usage according to the length of time one has spent on the streets. The paper concludes by discussing the theoretical implications of the findings and suggesting a number ...
1,293 citations
TL;DR: The research discussed here is based on the assumption that targets play an active role in the identity negotiation process, and suggests that perceivers and targets enter their interactions with independent and sometimes conflicting agendas that are resolved through a process of identity negotiation.
Abstract: This article traces a program of research on the interplay between social thought and social interaction. Early investigations of the impact of perceivers' expectancies on the actions of target individuals illuminated the contribution of perceivers to the identity negotiation process but overlooked the role of targets. The research discussed here is based on the assumption that targets play an active role in the identity negotiation process. Specifically, just as perceivers strive to validate their expectancies, targets seek to verify their self-views. The nature and antecedents of the processes through which people verify their self-conceptions as well as the relationship of these activities to self-concept change and self-enhancement processes are discussed. This research suggests that perceivers and targets enter their interactions with independent and sometimes conflicting agendas that are resolved through a process of identity negotiation. The identity negotiation process therefore provides a theoretical context in which the interplay between other-perception and self-perception can be understood.
1,168 citations
TL;DR: It is argued here that in universes that do not recollapse, the only bound on the cosmological constantlambda is that it should not be so large as to prevent the formation of gravitationally bound states, and it turns out that the bound is quite large.
Abstract: In recent cosmological models, there is an "anthropic" upper bound on the cosmological constant $\ensuremath{\Lambda}$. It is argued here that in universes that do not recollapse, the only such bound on $\ensuremath{\Lambda}$ is that it should not be so large as to prevent the formation of gravitationally bound states. It turns out that the bound is quite large. A cosmological constant that is within 1 or 2 orders of magnitude of its upper bound would help with the missing-mass and age problems, but may be ruled out by galaxy number counts. If so, we may conclude that anthropic considerations do not explain the smallness of the cosmological constant.
1,132 citations
TL;DR: In this article, the carbon isotope compositions of the polysaccharide and lignin components of a variety of vascular plants, including the salt-marsh grass Spartina alterniflora, were investigated.
Abstract: Stable carbon isotope compositions of organic matter are now widely used to trace carbon flow in ecosystems, and have been instrumental in shaping current perceptions of the importance of terrestrial vegetation to estuarine and coastal marine environments. A general assumption in these and other studies relying on carbon isotope compositions for source identification of organic matter has been that the major biochemical components of plant tissues are isotopically invariant. We report here large differences between the carbon isotope compositions of the polysaccharide and lignin components of a variety of vascular plants, including the salt-marsh grass Spartina alterniflora, and demonstrate that the carbon isotope composition of Spartina detritus gradually changes during biogeochemical processing as polysaccharides are preferentially removed, leaving a material that is relatively enriched in lignin-derived carbon and depleted in 13C.
985 citations
TL;DR: For both healthy adults and patients, active and avoidance coping were positively associated with negative life events and individuals who had more personal and environmental resources were more likely to rely on active coping and less likely to use avoidance coping.
Abstract: This study examined personal and contextual predictors of active and avoidance coping strategies in a community sample of over 400 adults and in a sample of over 400 persons entering psychiatric treatment for unipolar depression. Sociodemographic factors of education and income (except for active-cognitive coping), personality dispositions of self-confidence and an easy-going manner, and contextual factors of negative life events and family support each made a significant incremental contribution to predicting active and avoidance coping. Among both healthy adults and patients, active and avoidance coping were positively associated with negative life events. Individuals who had more personal and environmental resources were more likely to rely on active coping and less likely to use avoidance coping. Moreover, for both groups, most of the predictors continued to show significant relations with active and avoidance coping strategies even after the stable component in coping was controlled in a longitudinal design. A comprehensive framework to understand the determinants of coping can be of practical value in suggesting points for therapeutic interventions aimed at fostering more adaptive coping efforts.
810 citations
01 Dec 1987
TL;DR: A framework for supporting schema evolution is established, the semantics of schema evolution are defined, and the implementation of the implementation is discussed.
Abstract: Object-oriented programming is well-suited to such data-intensive application domains as CAD/CAM, AI, and OIS (office information systems) with multimedia documents. At MCC we have built a prototype object-oriented database system, called ORION. It adds persistence and sharability to objects created and manipulated in applications implemented in an object-oriented programming environment. One of the important requirements of these applications is schema evolution, that is, the ability to dynamically make a wide variety of changes to the database schema. In this paper, following a brief review of the object-oriented data model that we support in ORION, we establish a framework for supporting schema evolution, define the semantics of schema evolution, and discuss its implementation.
760 citations
TL;DR: In this paper, the amplitudes of the Green functions are found by solving a linear system of equations and the interpolating curve is a linear combination of Green functions centered at each data point.
Abstract: Green functions of the biharmonic operator, in one and two dimensions, are used for minimum curvature interpolation of irregularly spaced data points. The interpolating curve (or surface) is a linear combination of Green functions centered at each data point. The amplitudes of the Green functions are found by solving a linear system of equations. In one (or two) dimensions this technique is equivalent to cubic spline (or bicubic spline) interpolation while in three dimension it corresponds to multiquadric interpolation. Although this new technique is relatively slow, it is more flexible than the spline method since both slopes and values can be used to find a surface. Moreover, noisy data can be fit in a least squares sense by reducing the number of model parameters. These properties are well suited for interpolating irregularly spaced satellite altimeter profiles. The long wavelength radial orbit error is suppressed by differentiating each profile. The shorter wavelength noise is reduced by the least squares fit to nearby profiles. Using this technique with 0.5 million GEOS-3 and SEASAT data points, it was found that the marine geoid of the Caribbean area is highly correlated with the sea floor topography. This suggests that similar applications, in more remote, areas may reveal new features of the sea floor.
721 citations
668 citations
TL;DR: This paper found that the content of network television news accounts for a high proportion of aggregate changes (from one survey to another) in U.S. citizens' policy preferences, while special interest groups tend to have a negative impact.
Abstract: Democratic theory must pay attention to what influences public opinion. In this study the content of network television news is shown to account for a high proportion of aggregate changes (from one survey to another) in U.S. citizens' policy preferences. Different news sources have different effects. News commentators (perhaps reflecting elite or national consensus or media biases) have a very strong positive impact, as do experts. Popular presidents tend to have positive effects, while unpopular presidents do not. In contrast, special interest groups tend to have a negative impact.
01 Jun 1987
TL;DR: A class of information passing strategies is considered which suffices to describe most query evaluation algorithms in the database literature, and it is shown that these strategies may always be implemented by rewriting a given program and evaluating the rewritten program bottom-up.
Abstract: This paper considers the efficient evaluation of recursive queries expressed using Horn Clauses. We define sideways information passing formally and show how a query evaluation algorithm may be defined in terms of sideways information passing and control. We then consider a class of information passing strategies which suffices to describe most query evaluation algorithms in the database literature, and show that these strategies may always be implemented by rewriting a given program and evaluating the rewritten program bottom-up. We describe in detail several algorithms for rewriting a program. These algorithms generalize the Counting and Magic Sets algorithms to work with arbitrary programs. Safety and optimality of the algorithms are also considered.
TL;DR: In this article, the Wigner-function formulation is extended to systems having only a finite number of orthogonal states, where observables like states are represented by real functions on the discrete phase space.
TL;DR: It is proposed that conceptualizing cognition an affect as partially independent mental systems helps resolve some long-standing paradoxes regarding people's responses to self-relevant social feedback.
Abstract: Self-consistency theory assumes that people want others to treat them in a predictable manner. Selfenhancement theory contends that people want others to treat them in a positive manner. We attempted to help reconcile the two theories by testing the hypothesis that people's cognitive responses conform to self-consistency theory and their affeetive responses conform to self-enhancement theory. We presented individuals who possessed either positive or negative self-concepts with either favorable or unfavorable social feedback. We then measured cognitive reactions to the feedback (e.g., perceived self-descriptiveness) and alfective reactions to the feedback (e.g., mood states). Cognitive responses were primarily driven by the consistency of the feedback and affeetive responses were controlled by how enhancing it was. We propose that conceptualizing cognition and affect as partially independent mental systems helps resolve some long-standing paradoxes regarding people's responses to selfrelevant social feedback.
TL;DR: The ORION data model as mentioned in this paper consolidates and modifies a number of major concepts found in many object-oriented systems, such as objects, classes, class lattice, methods, and inheritance.
Abstract: Presented in this paper is the data model for ORION, a prototype database system that adds persistence and sharability to objects created and manipulated in object-oriented applications. The ORION data model consolidates and modifies a number of major concepts found in many object-oriented systems, such as objects, classes, class lattice, methods, and inheritance. These concepts are reviewed and three major enhancements to the conventional object-oriented data model, namely, schema evolution, composite objects, and versions, are elaborated upon. Schema evolution is the ability to dynamically make changes to the class definitions and the structure of the class lattice. Composite objects are recursive collections of exclusive components that are treated as units of storage, retrieval, and integrity enforcement. Versions are variations of the same object that are related by the history of their derivation. These enhancements are strongly motivated by the data management requirements of the ORION applications from the domains of artificial intelligence, computer-aided design and manufacturing, and office information systems with multimedia documents.
TL;DR: Requirement for the study of correlations between malignancy grade scoring, and recurrence and survival rates are presented, including factors as patient selection, clinical staging, and follow-up principles.
Abstract: A review of histologic classification systems for grading of malignancy in squamous cell carcinomas of the head and neck region is presented. Reasons behind the varying results obtained in studies using histomorphologic grading schemes are presented and potential errors involved in this type of clinical research are discussed. Requirements for the study of correlations between malignancy grade scoring, and recurrence and survival rates are presented. These include factors as patient selection, clinical staging, and follow-up principles. Special attention must be given to treatment modalities, establishment of negative surgical margins and occurrence of regional lymph node and/or distant metastases.
TL;DR: An improvement in precision beyond the limit set by the vacuum-state or zero-point fluctuations of the electromagnetic field is reported for the measurement of phase modulation in an optical interferometer.
Abstract: An improvement in precision beyond the limit set by the vacuum-state or zero-point fluctuations of the electromagnetic field is reported for the measurement of phase modulation in an optical interferometer. The experiment makes use of squeezed light to reduce the level of fluctuations below the shot-noise limit. An increase in the signal-to-noise ratio of 3.0 dB relative to the shot-noise limit is demonstrated, with the improvement currently limited by losses in propagation and detection and not by the degree of available squeezing.
TL;DR: In this paper, historical evidence pertaining to self hood is reviewed and a scheme of stages is delineated, according to which the modern self and its uncertainties have evolved, and the historical data are then reviewed in connection with the following four major problems regarding the self: knowing and conceptualizing the self; defining or creating the self, understanding one's potential and fulfilling it; and relating the single self to society.
Abstract: In this article, historical evidence pertaining to self hood is reviewed. A scheme of stages is delineated, according to which the modern self and its uncertainties have evolved. The historical data are then reviewed in connection with the following four major problems regarding the self: knowing and conceptualizing the self; defining or creating the self; understanding one's potential and fulfilling it; and relating the single self to society.
TL;DR: Deux experiences etudient aupres d'enfants âges de 2 a 3 mois and de 6 a 8 mois les preferences envers des visages de femmes dont le caractere attractif a ete evalue par des adultes.
Abstract: Deux experiences etudient aupres d'enfants âges de 2 a 3 mois et de 6 a 8 mois les preferences envers des visages de femmes dont le caractere attractif a ete evalue par des adultes
TL;DR: It is reported here that a significant quantity of tau in the central nervous system is phosphorylated in situ at or near the Tau-1 epitope, preventing the binding of the Tau -1 antibody.
Abstract: The monoclonal antibody, Tau-1, which had previously been used to localize tau to the axonal compartment in brain has been reutilized for light and electron microscopic immunohistochemistry following phosphatase treatment of tissue. We report here that a significant quantity of tau in the central nervous system is phosphorylated in situ at or near the Tau-1 epitope, preventing the binding of the Tau-1 antibody. Upon removal of this/these phosphate group(s), however, Tau-1 was observed in the somatodendritic compartment of neurons as well as in axons. Furthermore, intense staining was also observed in astrocytes and in perineuronal glial cells. This immunoreactivity was present along the lengths of microtubules and on ribosomes (polysomes). Treatment of immunoblots of extracts of whole cerebral cortex with phosphatase confirmed the immunohistochemical results in that a 50-65% increase in Tau-1 binding to the tau region of the blot was noted. Moreover, a novel monoclonal antibody, Tau-2, was also used in these experiments. This antibody binds only to tau and localizes along microtubules in axons, somata, dendrites, and astrocytes and on ribosomes (polysomes) without phosphatase pretreatment.
TL;DR: Seven cyclists exercised at 70% of maximal O2 uptake until fatigue until fatigue on three occasions, 1 wk apart, with three-fourths of total carbohydrate oxidation during the second exercise bout accounted for by the euglycemic glucose infusion rate.
Abstract: Seven cyclists exercised at 70% of maximal O2 uptake (VO2max) until fatigue (170 +/- 9 min) on three occasions, 1 wk apart. During these trials, plasma glucose declined from 5.0 +/- 0.1 to 3.1 +/- ...
TL;DR: In this paper, it was shown that if a Heegaard splitting of a nonsufficiently large 3-manifold has the property that there exist essential disks, one in each of the two handlebodies, whose boundaries are disjoint, then the splitting is reducible.
TL;DR: In this paper, a new formulation of the detection filter problem is generated by assignment of the closed-loop eigenstructure under certain constraints, and necessary and sufficient conditions for the solution of these algebraic equations are determined which produce a complete theory for detection filters.
Abstract: A new formulation of the detection filter problem is generated by assignment of the closed-loop eigenstructure under certain constraints. Detection filters, which are actually a specific class of observers, fix the output error direction of the system so that it can be associated with a particular failure mode and its known design failure direction. The derivation of detection filters from an eigensystem assignment approach permits a very transparent theory. The detection filter gains and closed-loop eigenvectors are obtained from a set of simultaneous equations. Necessary and sufficient conditions for the solution of these algebraic equations are determined which produce a complete theory for detection filters.
TL;DR: This paper presents a unified approach for efficient model checking under a broad class of generalized fairness constraints in a branching time framework extending that of Clarke et al. (1983), and argues that branching time logic is always better than linear time logic for model checking.
TL;DR: Depressive symptoms at baseline, low education, physical disability or presence of chronic conditions, poor perceived health, personal uncertainty, residential move, job loss, money problems, anomy, and social isolation were independently associated with increased risk of depressive symptoms at the nine-year follow-up.
Abstract: The association between status attributes, personal resources, life stress, physical health, and occurrence of depressive symptoms nine years later was assessed by the 1965 Human Population Laboratory survey of a random sample of 6,928 adults in Alameda County, California, and by a subsequent follow-up survey in 1974. In multiple logistic analyses, depressive symptoms at baseline, low education, physical disability or presence of chronic conditions, poor perceived health, personal uncertainty, residential move, job loss, money problems, anomy, and social isolation were independently associated with increased risk of depressive symptoms at the nine-year follow-up. Age, low income, ethnicity, marital status, separation or divorce, and health practices at baseline were unrelated to depressive symptoms. These results underscore both the multifactorial nature of depression and the importance of prospective analyses of depressive phenomena.
[...]
TL;DR: A calculus analogous to weakest preconditions is suggested as an aid to deriving programs from their specifications as well as a set of algebraic laws for Dijkstra's nondeterministic sequential programming language.
Abstract: A complete set of algebraic laws is given for Dijkstra's nondeterministic sequential programming language. Iteration and recursion are explained in terms of Scott's domain theory as fixed points of continuous functionals. A calculus analogous to weakest preconditions is suggested as an aid to deriving programs from their specifications.
TL;DR: It is concluded that both the rate of synonymous substitution and the degree of codon usage bias largely reflect the intensity of selection at the translational level.
Abstract: Genes sequences from Escherichia coli, Salmonella typhimurium, and other members of the Enterobacteriaceae show a negative correlation between the degree of synonymous-codon usage bias and the rate of nucleotide substitution at synonymous sites. In particular, very highly expressed genes have very biased codon usage and accumulate synonymous substitutions very slowly. In contrast, there is little correlation between the degree of codon bias and the rate of protein evolution. It is concluded that both the rate of synonymous substitution and the degree of codon usage bias largely reflect the intensity of selection at the translational level. Because of the high variability among genes in rates of synonymous substitution, separate molecular clocks of synonymous substitution might be required for different genes.
TL;DR: The authors' observations on the cellular immune response to type-A influenza suggest the existence of two distinct pathways of protein antigen presentation to T lymphocytes, one of which is involved with presentation of antigens introduced into the presenting cell from without and the second which is tentatively designated as an endogenous presentation pathway.
Abstract: Our observations on the cellular immune response to type-A influenza suggest the existence of two distinct pathways of protein antigen presentation to T lymphocytes. One of these pathways is involved with presentation of antigens introduced into the presenting cell from without. This exogenous presentation pathway is the well-recognized route of presentation of soluble and particulate antigens to T lymphocytes. This pathway probably involves uptake of antigen into endocytic vesicles, alteration of antigen within an intracellular compartment, and subsequent display of antigen on the presenting cell surface (Unanue 1984). The second pathway is one which we have tentatively designated as an endogenous presentation pathway. The constraints on this pathway have yet to be fully defined. At a minimum, this pathway appears to involve the presentation of antigens which are synthesized de novo in the presenting cell utilizing the cell's biosynthetic machinery. This pathway may also handle preformed antigens located within the cytosolic compartment of the presenting cell. Perhaps the most striking feature of these two antigen presentation pathways is the close association between the MHC restriction of an antigen-specific T lymphocyte and the pathway of antigen presentation to that T lymphocyte. Our data suggest that this association holds both at the effector level and at the level of induction of T lymphocytes. Thus, presentation of a given antigen by the endogenous pathway preferentially triggers a response from class I MHC-restricted T lymphocytes directed to that antigen. The molecular basis for this link of class I MHC-restriction to the endogenous pathway and MHC class II restriction to the exogenous pathway is unknown. It seems likely that interactions between MHC molecules and antigen within the presenting cell may be critical for the demarcation of these pathways. Thus, for example, antigen presented by the endogenous route may only be able to associate intracellularly with newly synthesized or recycling class I MHC molecules. An understanding of the molecular basis of this phenomenon will require detailed information on the expression, intracellular trafficking, and transport of class I and class II MHC molecules in the antigen-presenting cell. An unresolved issue, at least in the case of viral antigens, is the nature and form of the antigenic moieties presented by the exogenous and endogenous pathways. In the case of viral antigen presentation to class II MHC-restricted T lymphocytes, there is strong, albeit indirect, evidence for processing of antigen and recognition of fragments of viral polypeptides (Lamb et al. 1982, Hackett et al. 1983).(ABSTRACT TRUNCATED AT 400 WORDS)