Mean Theory Research Articles

Does SCOT Answer? A Comment

To model or not to model? That appears to be the underlying question addressed in the debate between Mr. Clayton and Drs. Pinch and Bijker. Can the evolution of individual artifacts be synthesized into a coherent and meaningful theory of technological development? Should we even try? I am somewhat reluctant to wade into the whirlpool of the debate because Clayton is a friend and colleague, while my own research on the American bicycle industry has been greatly influenced by Pinch and Bijker's work. Instead, I will ask four admittedly speculative questions that I hope may shed some light.

Integrable systems on quad-graphs

Discrete (lattice) systems constitute a well-established part of the theory of integrable systems. They came up already in the early days of the theory (see, e.g. [11, 12]), and took gradually more and more important place in it (cf. a review in [18]). Nowadays many experts in the field agree that discrete integrable systems are in many respects even more fundamental than the continuous ones. They play a prominent role in various applications of integrable systems such as discrete differential geometry (see, e.g., a review in [9]). Traditionally, independent variables of discrete integrable systems are considered as belonging to a regular square lattice Z (or its multidimensional analogs Z). Only very recently, there appeared first hints on the existence of a rich and meaningful theory of integrable systems on nonsquare lattices and, more generally, on arbitrary graphs. The relevant publications are almost exhausted by [2, 3, 5, 6, 16, 20, 21, 22]. We define integrable systems on graphs as flat connections with the values in loop groups. This is very natural definition, and experts in discrete integrable systems will not only immediately accept it, but might even consider it trivial. Nevertheless, it crystallized only very recently, and seems not to appear in the literature before [3, 5, 6]. (It should be noted that a different framework for integrable systems on graphs is being developed by Novikov with collaborators [16, 20, 21].) We were led to considering such systems by our (with Hoffmann) investigations of circle patterns as objects of discrete complex analysis: in [5, 6] we demonstrated that certain classes of circle patterns with the combinatorics of regular hexagonal lattice

Neurobiology of Generalized Anxiety Disorder

On reviewing the literature on GAD and trying to summarize the various developments in the field of neurobiology of GAD, we see that a range of hypotheses try to explore and integrate the observations found into potentially meaningful theories. Abnormal serotonergic and GABAergic function occur in many patients with GAD. Functional imaging data have shown increased cortical activity and decreased basal ganglia activity in patients with GAD, which reverses with treatment, but it is apparent that no one theory is sufficiently comprehensive to propose a unitary hypothesis for the development of GAD and other anxiety disorders. GAD is a relatively new diagnosable condition, first introduced into the classification system of psychiatric disorders in 1980, and since then has undergone a series of changes in its conceptualization, with some investigators questioning the existence of the condition as a distinct entity. Any inferences that may be drawn from various studies must be guarded, and it is appropriate to compare studies using the same diagnostic criteria. Significant research has been done and may lead to exciting new discoveries in the treatment of anxiety disorders in general and GAD in particular. Gray's model of behavioral inhibition, in which the septohippocampal system acts by assessing stimuli for the presence of danger and, when that is detected, activates the behavioral-inhibition circuit, provides a neuroanatomic conceptualization that has been expanded by preclinical research. Some exciting work has been done on CRF and the concept of development, vulnerability, and kindling and some investigators have contributed to this area of interest. This concept supports the hypothesis that a genetic predisposition, coupled with early stress, in the crucial phases of development may result in a phenotype that is neurobiologically vulnerable to stress and may lower an individual's threshold for developing anxiety or depression on additional stress exposure. The pharmaceutical industry is exploring treatment options using CRF antagonists, and research on other neuropeptides, especially NPY, will be of interest. Research on neurosteroids also may bring the opportunity for pharmacologic treatment approaches. Future research on the startle reflex and on the NMDA and the metabotropic glutamate receptors is important. Future studies of a more homogenous patient population and using more sophisticated techniques, such as molecular genetic strategies and better imaging techniques, may answer some of the outstanding questions.

Altruism and the Endurance of the Good

Egoism is a pervasive trait in modern market societies that encourages people to focus upon their own self-interest above all else. Third-sector organizations, by contrast, are frequently termed “altruistic.” This essay elucidates the meaning of “altruism” as it applies to these organizations. Moral altruism means direct concern for another's well being—whoever that person might be. This study rejects psychological egoism as a meaningful psychological theory, and ethical egoism as a coherent moral position; it discusses empirical studies of altruism in rescuers of Jews in Nazi-occupied Europe as proof against the former form of egoism and Kant's moral theory against the latter. The essay then argues that altruism is a form of public action in Hannah Arendt's sense of this term. The essay concludes that third-sector organizations are altruistic insofar as they engage in public action, thereby, treating beneficiaries with respect for their individuality.

Anti-Realist Semantics

I argue that the implementation of theDummettian program of an ``anti-realist'' semanticsrequires quite different conceptions of the technicalmeaning-theoretic terms used than those presupposed byDummett. Starting from obvious incoherences in anattempt to conceive truth conditions as assertibilityconditions, I argue that for anti-realist purposesnon-epistemic semantic notions are more usefully kept apart from epistemic ones rather than beingreduced to them. Embedding an anti-realist theory ofmeaning in Martin-Lof's Intuitionistic Type Theory(ITT) takes care, however, of many notorious problemsthat have arisen in trying to specify suitableintuitionistic notions of semantic value,truth-conditions, and validity, taking into accountthe so-called ``defeasibility of evidence'' forassertions in empirical discourses.

Tolerance and auto-immunity: 50 years after Burnet.

Fifty years ago Sir F. Macfarlane Burnet published his first fundamental contribution to the theory of immune tolerance he perfected 10 years later. Since then an impressive amount of new information on the function of the immune system has been gathered. As any original meaningful theory, Burnet's hypothesis on the development of immune tolerance has undergone extensive modifications to take into account all these new findings. An improved understanding of the mechanisms of tolerance has led to new possibilities for the treatment of auto-immune diseases. All new information in the field of immune function is rooted in Burnet's contribution which set the stage for the development of modern immunology.

Existential Computer Anxiety and Changes in Computer Technology: What Past Research on Computer Anxiety Has Missed

In this article we propose that the existing literature on computer anxiety has neglected to consider two issues: 1) that there is an existential element to computer anxiety, and 2) that computer technology has undergone historical changes that bring with them subsequent changes in the metaphors we use to understand computers. Failure to consider these two issues has resulted in a vast body of literature that is inconsistent and ultimately of little practical or theoretical value. We discuss some of the problems in the literature that defines, develops measurement instruments for, posits correlates of, and attempts to “cure” computer anxiety and explain how attention to the two issues described above could mitigate some of these problems. Finally, we suggest ways in which attention to these two issues could help in the development of a meaningful theory to support investigation into computer anxiety.

Sykepleien i spenningsfeltet mellom teori og praksis — konflikt eller dialog?

Nursing education in Norway has since its formalization comprized both theory and practice. During the last 20 years there has been a reduction on the part of clinical practice in the programme from 67 % to 35 %. The theoretical courses have expanded correspondingly. The changes have occured step by step as a consequence of new rules and regulations for nursing education put forward by the Minstry of Social Affairs, now the Minstry of Culture, Science and Research. Nursing education is now organized within the academic educational system and graduate nursing studies at University level started in 1977. This has opened up for the possibility of developing nursing within the framework of scientific tradition. In this article the focus will be on the theoretical development that has place within nursing. Questions will be posed, i.e.: “What is meaningful theory for a practical profession”, and “What can theory tell us concerning the practical performance of nursing?”. The discussion will to a large extent re...

Reptation in linear systems

A model suitable for reptation in linear systems under a driving field is proposed. Its dynamics is based on the decoupling of opposite repton jumps, and is essentially different from reptation in higher dimensions, namely the Rubinstein-Duke model (RDM). The stationary density and correlation functions are calculated perturbatively in the driving field. A meaningful mean field theory is also derived. Diffusion exhibits a strong drift velocity and band collapse. Also a peculiar scaling behavior is found. The results address the sensitivity of reptation process to the rules of motion and the boundary conditions.

What is the point? Concepts, description, and rigid designation

Millikan's nondescriptionist approach applies an account of meaning to concepts in terms of designation. The essentialism that provides the principal grounds for rigid designation, however, receives no empirical support from concepts. Whatever the grounding, this view not only faces the problems of rigid designation in theories of meaning, it also calls for a role for pragmatics more consonant with descriptionist theories of concepts.

SCATTERING OF 3HE AND 4HE ATOMS FROM 4HE CLUSTERS

We develop a microscopic theory of elastic and inelastic scattering and sticking of3He and4He atoms impinging on superfluid4He clusters. A number of essential aspects must be observed in a physically meaningful and reliable theory of such scattering processes. These are all connected with multiparticle processes, particularly the possibility of energy loss. These processes are (a) the coupling to low-lying excitations which is manifested in a finite imaginary part of the self energy, (b) the interaction with roton–like excitations and the broadening of the roton minimum due to finite–size effects, and (c) the discreteness of low–lying excitations in helium clusters.

On reduction-based process semantics

A formulation of semantic theories for processes which does not rely on the notion of observables or convergence is studied. The new construction is based solely on a reduction relation and equational reasoning, but can induce meaningful theories for processes, both in weak and strong settings. The resulting theories in many cases coincide with, and sometimes generalise, observation-based formulation of behavioural equivalence. The basic construction of reduction-based theories is studied, taking a simple name passing calculus (called ν-calculus) and its extensions as an example. Results concerning the application of our construction to other calculi are also briefly discussed.

Iterative processes: A survey of convergence theory using Lyapunov second method

Let x{sup k}, k {ge} 1, be some sequence of iterations. The diversity of motion laws governing the transition from the current iteration x{sup k} to the next iteration x{sup k+1} generates an infinite set of facts concerning convergence of the sequence x{sup k}. This richness complicates the construction of a general and at the same time substantively meaningful theory that combines all the available facts into one whole. Instead of focusing on convergence of (x{sup k}), the approach presented in this paper examines convergence to zero of a sequence of values of a nonnegative functional evaluated on the iterative process. Such sequences are found to satisfy a number of fundamental conditions that are independent of the phase space, the motion law, and the particular functional chosen, i.e., these conditions are indeed general. Assertions regarding convergence of (x{sup k}) itself require new additional restrictions each time a new class of iterative processes is considered, and in this sense are not general. The proposed approach generalizes the well-established facts and also predicts many new ones.

ISING SPIN GLASS: RECENT PROGRESS IN THE FIELD THEORY APPROACH

A loop expansion around Parisi's replica symmetry breaking mean field theory is constructed, in zero field. We obtain the equation of state (and associated Parisi's solution) below the upper critical dimension du=6, and, in particular, explicit corrections in εlnt and (εlnt)2 with t=(Tc−T)/Tc and ε=6−d. This allows us to verify that standard scaling is satisfied with β=1+ε/2+0(ε2). We have also investigated the transverse (replicon) correlation function, particularly at zero overlap. Near du, G00 (p) ~ t/P4 (for p~0) is the most obvious obstacle to a meaningful theory in d=3. If we make the twofold assumption that (i) scaling applies, and (ii) the replicon propagator is dominated by the spectrum of the (small) transverse masses, we obtain the softer behavior G00(p) ~ (1/p2–η). (t/p1/v)β and a prediction for a soft replicon spectrum in tγk2γ/β γ/β instead of tk2 at du. We have checked tγ to one loop and work is in progress to check k2γ/β to the same order. Taking the above divergence in p−(d+2−η)/2 as the leading divergence defines the lower critical dimension d ℓ by d ℓ=2−η (d ℓ). Known values of η (at d=6, from the ε expansion at Tc, or from numerical work at d=4, 3) are compatible with d ℓ ~ 2.5±.3.

Rhetoric for Realism in Psychology

Greenwood's (1992) selection of arguments may be understood as being targeted at experimental psychologists. These arguments focus on empiricism's denial of meaningful theory, constructionism's denial of objectivity, and realism's avoidance of both, while allowing satisfactory insight into the social realm. I approve of Greenwood's approach, both its logic and its rhetoric, but I suggest some refinements. Greater attention to empiricist objections to realism, a different interpretation of the theory-ladenness of observations, and a firmer attack on the relativistic aspects of constructionism would make for a stronger argument.

Kinestatic Control: A Novel Theory for Simultaneously Regulating Force and Displacement

A new theory for the simultaneous control of force and displacement for a partially constrained end-effector is established based upon the general spatial stiffness of the manipulator. In general, the spatial stiffness of a compliant coupling that connects a pair of rigid bodies is used to map a small twist between the bodies into the corresponding interactive wrench. This mapping is based upon a firm geometrical foundation and establishes a positive-definite inner product (elliptic metric) that decomposes a general twist into a twist of freedom and a twist of compliance. A study of the invariant properties of this mapping leads to the discovery of what are defined as the eigen-screws of stiffness. Further, the spatial stiffness of a compliant coupling is modeled by theoretically replacing the coupling with a passive Stewart Platform-type parallel mechanism. It is important to recognize that this model does not depend upon the existence of a center-of-compliance. In fact, it describes a general state of spatial stiffness between any two rigid bodies. The culmination of these finding yields a practical and meaningful theory of Kinestatic Control, viz., the simultaneous regulation of force and displacement solely via the control of displacement.

Further Results on the Application of Entropies of Deterministic Functions to Information of Fuzzy Sets and Related Topics

The problem of expanding a meaningful entropic theory for fuzzy information cannot be thought of as being a mere (more or less formal) extension of Shannon theory. By using the information theory of deterministic functions, the present author had already obtained some results in this way, and he herein continues this approach. After a short background on the different entropies of deterministic functions and on membership entropy of fuzzy sets, successively mixed entropy of fuzzy sets, joint membership functions of independent fuzzy sets, and conditional entropy of fuzzy sets with respect to other fuzzy sets are considered; the problem of defining transinformation between fuzzy sets, as a generalisation of the well known Shannon concept, is then examined. One of the conclusions of the article is that it is possible to build up a meaningful information theory of fuzzy sets by using the entropy of deterministic functions.

Reliability of Ratings for Multiple Judges: Intraclass Correlation and Metric Scales

Scale-dependent procedures are presented for assessing the reliability of ratings for multiple judges using intraclass correlation. Scale type is defined in terms of admissible transformations, and standardizing transformations for ratio and in terval scales are presented to solve the problem of adjusting ratings for "arbitrary scale factors" (unit and/or origin of the scale). The theory of mean ingfulness of numerical statements is introduced and the coefficient of relational agreement (Stine, 1989b) is defined as the degree of agreement among judges, with respect to (scale-dependent) empirically meaningful relationships. Other topics discussed include the treatment of variability due to judges in relation to scale type, and the reliabili ty of magnitude estimates in psychophysics.

On the Theory of Meaningfulness of Ordinal Comparisons in Measurement: IIa

On the Theory of Meaningfulness of Ordinal Comparisons in Measurement: IIa

Dynamics and control of viscoelastic solids with contact and friction effects

THE DYNAMICSand conlrol of distributed systems subjected to frictional resistive forces has been an open problem in partial differential equations for many years, largely owing to the absence of a meaningful existence theory for dynamical systems with friction. The mathcmatical difficulties associated with Coulomb friction in problems of elastodynamics were pointed out in 1972 by Duvaut and Lions (see (I)) and has been the subject of much study in the intervening years. The finite-dimensional case has proved to be somewhat more tractable, and conditions for the existence of solutions of discrete dynamical problems with friction have been recently reported by Lbtstedt (2) and Jean and Pratt (3). The complexity of the problem can be appreciated by reviewing the work on dynamics of systems with frictionless contacts by, for example. Schatzman (4), Carrero and Pascali (5), Lotstedt (6), Amerio and Prouse (7). Amerio (8), and others. In recent papers, Oden and Martins (9, 10) pointed out that one of the principal sources of mathematical difficulty was the definition of frictional stresses on the contact surfaces charac- terized by Coulomb's law. However, an overwhelming volume of experimental data accumu- lated over a half century suggests that this law is inadequate for modeling actual contacts and resisIive forces on deformable bodies. By characterizing the actual normal compliance of elastic interfaces. a constitutive equation for an interface can be developed which yields results in agreement with a sizable collection of experimental results on static and dynamic friction (9). Moreover. the use of such interface constitutive laws in mathematical models of elastostatics, elastodynamics, and viscoelastodynamics problems with friction produces a tractable theory: results on the existence and local uniqueness of solutions to static problems in elaslicity with the Oden-Martins (9) nonlinear friction laws were recently established by Rabier el of. (II) and of dynamic problems on elasticity and viscoelasticity by Martins and Oden (10). These new theories and results set the stage for the study of the optimal control of such systems, taken up in the present paper. In the present study, we establish the existence of a class of optimal controls for a broad class of problems in the dynamics of linear viscoelastic bodies with contact and friction laws of the type introduced by Oden and Martins (9). We are able to show, under very mild restrictions