Indirect Representation Research Articles

Who is a Modeler?

Many standard philosophical accounts of scientific practice fail to distinguish between modeling and other types of theory construction. This failure is unfortunate because there are important contrasts among the goals, procedures, and representations employed by modelers and other kinds of theorists. We can see some of these differences intuitively when we reflect on the methods of theorists such as Vito Volterra and Linus Pauling on the one hand, and Charles Darwin and Dimitri Mendeleev on the other. Much of Volterra's and Pauling's work involved modeling; much of Darwin's and Mendeleev's did not. In order to capture this distinction, I consider two examples of theory construction in detail: Volterra's treatment of post-WWI fishery dynamics and Mendeleev's construction of the periodic system. I argue that modeling can be distinguished from other forms of theorizing by the procedures modelers use to represent and to study real-world phenomena: indirect representation and analysis. This differentiation between modelers and non-modelers is one component of the larger project of understanding the practice of modeling, its distinctive features, and the strategies of abstraction and idealization it employs.

Visual processing and the bodily self

The ‘body schema’ has traditionally been defined as a passively updated, proprioceptive representation of the body. However, recent work has suggested that body representations are more complex and flexible than previously thought. They may integrate current perceptual information from all sensory modalities, and can be extended to incorporate indirect representations of the body and functional portions of tools. In the present study, we investigate the source of a facilitatory effect of viewing the body on speeded visual discrimination reaction times. Participants responded to identical visual stimuli that varied only in their context: being presented on the participant’s own body, on the experimenter’s body, or in a neutral context. The stimuli were filmed and viewed in real-time on a projector screen. Careful controls for attention, biological saliency, and attribution confirmed that the facilitatory effect depends critically on participants attributing the context to a real body. An intermediate effect was observed when the stimuli were presented on another person’s body, suggesting that the effect of viewing one’s own body might represent a conjunction of an interpersonal body effect and an egocentric effect.

Lagrangian description of the radiation damping

We present a Lagrangian formalism to the dissipative system of a charge interacting with its own radiation field, which gives rise to the radiation damping \cite{Heitler}, by the indirect representation doubling the phase-space dimensions.

Atheist Jew or Atheist Jew: Freud’s Jewish Question and Ours

The title for this article takes its lead from Freud's famous self-description in his October 1918 letter to the Swiss Analyst-Pastor Oskar Pfister: Quite by the way, why did none of the devout create psychoanalysis? Why did one have to wait for a completely godless Jew--einen ganz gottlosen Juden?' Numerous analysts, scholars, theologians, and commentators have endeavored to parse the meanings of and relationships between and in Freud's pithy phrase and no-less pithy life. Their efforts have led to a plethora of sequels to Freud's own selfdescription: non-Jewish Jew, secular Jew, modern Jew, psychological Jew, self-hating Jew, renegade Jew, ambivalent Jew. After detailing some of Freud's own explicit assertions of Jewish identity, this essay will examine some of the ways and whys Freud's Jewishness has become a major focus of contemporary reflections on the man, his writings, and his legacy. The diverse reactions to the phrase Godless suggest an uncanny discomfort. There are actually at least two sources of discomfort. The first source is generated by the question: What is a Jew? Is Jew a religious designation? If so, then the notion of is either an oxymoron or an indirect representation, such as Freud analyzed in the dream work or noted in Jokes and Their Relation to the Unconscious, and it recalls Heine's witticism, cited by Freud in Jokes, my fellow unbeliever Spinoza.2 Or, conversely, is the notion of related to the German term Judentum, which condenses three fields

The representer method, the ensemble Kalman filter and the ensemble Kalman smoother: A comparison study using a nonlinear reduced gravity ocean model

This paper compares contending advanced data assimilation algorithms using the same dynamical model and measurements. Assimilation experiments use the ensemble Kalman filter (EnKF), the ensemble Kalman smoother (EnKS) and the representer method involving a nonlinear model and synthetic measurements of a mesoscale eddy. Twin model experiments provide the “truth” and assimilated state. The difference between truth and assimilation state is a mispositioning of an eddy in the initial state affected by a temporal shift. The systems are constructed to represent the dynamics, error covariances and data density as similarly as possible, though because of the differing assumptions in the system derivations subtle differences do occur. The results reflect some of these differences in the tangent linear assumption made in the representer adjoint and the temporal covariance of the EnKF, which does not correct initial condition errors. These differences are assessed through the accuracy of each method as a function of measurement density. Results indicate that these methods are comparably accurate for sufficiently dense measurement networks; and each is able to correct the position of a purposefully misplaced mesoscale eddy. As measurement density is decreased, the EnKS and the representer method retain accuracy longer than the EnKF. While the representer method is more accurate than the sequential methods within the time period covered by the observations (particularly during the first part of the assimilation time), the representer method is less accurate during later times and during the forecast time period for sparse networks as the tangent linear assumption becomes less accurate. Furthermore, the representer method proves to be significantly more costly (2–4 times) than the EnKS and EnKF even with only a few outer iterations of the iterated indirect representer method.

Euler–Lagrange equations for the spectral element shallow water system

We present the derivation of the discrete Euler–Lagrange equations for an inverse spectral element ocean model based on the shallow water equations. We show that the discrete Euler–Lagrange equations can be obtained from the continuous Euler–Lagrange equations by using a correct combination of the weak and the strong forms of derivatives in the Galerkin integrals, and by changing the order with which elemental assembly and mass averaging are applied in the forward and in the adjoint systems. Our derivation can be extended to obtain an adjoint for any Galerkin finite element and spectral element system. We begin the derivations using a linear wave equation in one dimension. We then apply our technique to a two-dimensional shallow water ocean model and test it on a classic double-gyre problem. The spectral element forward and adjoint ocean models can be used in a variety of inverse applications, ranging from traditional data assimilation and parameter estimation, to the less traditional model sensitivity and stability analyses, and ensemble prediction. Here the Euler–Lagrange equations are solved by an indirect representer algorithm.

The Allures and Deceptions of Democracy

The Allures and Deceptions of Democracy

New mediation and direct representation: reconceptualizing representation in the digital age

This article explores three responses to the emergence of digitally mediated political representation. The first regards disintermediation as a basis for direct democracy, transcending the traditional arrangements and institutions of political representation. The second model institutionalizes digital information and communication technology (ICT) within the rational-bureacratic framework of existing governance. The third model is based upon a reconceptualization of democratic representation, based upon new notions of accountability, plurality and authentic reality. It is argued that virtual deliberation and indirect representation are under severe political strain and that digitally-mediated direct representation could provide a basis for a more dialogical and deliberative democracy in place of the dialogue of the deaf which tends to characterize contemporary political representation.

The Lonely Citizen: Indirect Representation in an Age of Networks

This article explores what it means to be represented and how the nature of representation might change in an age of networks. Citizens' perceptions of political connection and disconnection are examined on the basis of quantitative and qualitative surveys. A typology of political connection is presented and then expanded on the basis of the discussion of four potentially democratizing characteristics of digital information and communication technologies.

Landscape ecological analysis of barn owl pellet data from the Drava lowlands, Hungary

Small mammal fauna monitoring in the Drava Lowlands has been done partly by barn owl pellet collecting and analysis. In the present study the correlations between landscape patterns and barn owl food composition (i.e. the indirect representation of small mammal communities) were analysed using an approach how the cummulated data of particular breeding pairs can be interpreted as characteristic for the patch composition of the mosaic landscape considerably larger than the hunting range of barn owls. For landscape ecological analysis CORTNE LANDCOVER 1:50.000 mapping categories were applied, based on which natural or semi-natural areas, differing from each other also in their barn owl hunting qualities, were differentiated. Three larger areas along river Drava were investigated: two in the upper reach monitoring zone (ZákányPorrogszentkirály, and Berzence-Heresznye), and one in the lower Drava reach (Drávaiványi-Szaporca). In the two upper-reach zones the localities differed from the greater scale landscape in less than 30% of the patches, with only 3-5 patches showing significant difference. In the lower reach there was one sampling locality with 6 patches differing from the greater-scale area, although in the entire lower section 33% or less difference was found between patch compositions of the two scales. Based on patch overlap calculations and homogeneity tests it was concluded that small mammal faunal data of the localities can be cumulated and can be evaluated on much larger landscape ecological scales than barn owl hunting ranges.

Picard iterations for a finite element shallow water equation model

ADCIRC, a finite element circulation model for shelves, coasts and estuaries, will be used for variational data assimilation. The nonlinear Euler–Lagrange (EL) problem will be solved using the iterated indirect representer algorithm. This algorithm makes such large, nonlinear but functionally smooth optimization problems feasible by iterating on linear approximations of the nonlinear problem (Picard iterations) and by making preconditioned searches in the “data subspace” at each iterate. Before solving the nonlinear EL using such Picard iterations, it essential that the iteration scheme be carefully examined within the framework of the nonassimilative or forward problem. The purpose of this paper is (1) to detail a Picard iteration procedure for ADCIRC, including the problematic bottom friction term; (2) to examine the ability of the iteration scheme to recover the nonlinear forward solution from deficient background fields; and (3) to present a study of different interpolation methods for reducing the memory/disk requirements of the iteration scheme. The iteration scheme is shown to be quite robust in its ability to recover the nonlinear solution from a variety of deficient background fields. A new cubic Hermitian interpolation method is shown to be a more effective alternative to standard linear interpolation for reducing memory/disk requirements, especially for high frequency overtides.

Robust ability of IFN-gamma to upregulate class II MHC antigen expression in tumor bearing rat brains.

T cells are attractive for delivering therapy to brain tumor, especially disseminated micro-tumor. However, to trigger effector function, tumor antigen must be re-presented to T cells, via major histocompatibility complex (MHC) proteins, at the tumor site. In normal brain, MHC+ antigen-presenting cells (APC) are rare, but abundant after gamma interferon (IFN-gamma) injection. Here we studied tumor-bearing brains. IFN-gamma (or buffer) was injected stereotactically into brains with established tumors from a panel of immunologically varied glioma cell lines, some expressing b-galactosidase as a micro-tumor marker. Four days later, cryostat sections were stained for tumor and MHC proteins. In phosphate-buffered saline-injected controls, class II MHC+ potential APC (microglia, macrophages) were seen only at (some) tumor sites. In rats that received IFN-gamma, class II+ potential APC were widespread, including all actual and potential micro-tumor sites and all tumor-free areas. In the same slides, neither class I nor class II MHC antigen was detected in neural cells or most tumor cells. This MHC pattern favors indirect re-presentation of tumor antigen, by tumor-adjacent APC. The robust response to IFN-gamma might also be exploited in other ways: activated microglia and macrophages can attack tumor directly, and class II+ APC may help mark micro-tumor sites.

Evolutionary graph generation system with transmigration capability and its application to arithmetic circuit synthesis

The paper presents a novel graph-based evolutionary optimisation technique called evolutionary graph generation (EGG) and its application to the design of fast constant-coefficient multipliers using parallel counter-tree architecture. A unique feature of EGG is its capability to handle the general graph structures directly in the evolution process instead of encoding the graph structures into indirect representations, such as bit strings and trees. The paper also demonstrates that the evolution process of EGG can be accelerated by a simple operation, called 'transmigration', which is to import previously generated good solutions (constant-coefficient multipliers) for creating multipliers with different target coefficients. The authors' observation shows that transmigration accelerates a typical evolutionary run by an average of 8.7 times. This implies that the EGG system can acquire and reuse useful subcircuit structures contained in the previously generated multipliers during the evolution process.

Indirect Analytic Representation of Foucault's Pendulum

A complex representation of the equations of motion of the Foucault's pendulum is considered and the inverse problem is solved to derive an indirect analytic representation. Both real LR(i) and imaginary LI(i) parts of the derived complex valued Lagrangian are found to reproduce the equations of motion via the Euler-Lagrange equations. The expressions for LR(i) and LI(i) are not connected by a gauge term thereby forming a set of inequivalent Lagrangians. In an appropriate limit LI(i) is found to reproduce the Lagrangian obtained by implementing the usual Coriolis theorem while in some other limit LR(i) and LI(i) give the indirect and the direct analytic representations for a set of two uncoupled harmonic oscillators.

Graph-based evolutionary design of arithmetic circuits

We present an efficient graph-based evolutionary optimization technique, called evolutionary graph generation (EGG), and the proposed approach is applied to the design of combinational and sequential arithmetic circuits based on parallel counter-tree architecture. The fundamental idea of EGG is to employ general circuit graphs as individuals and manipulate the circuit graphs directly using new evolutionary graph operations without encoding the graphs into other indirect representations, such as the bit strings used in genetic algorithm (GA) proposed by Holland (1992) and trees used in genetic programming (GP) proposed by Koza et al. (1997). In this paper, the EGG system is applied to the design of constant-coefficient multipliers and the design of bit-serial data-parallel adders. The results demonstrate the potential capability of EGG to solve the practical design problems for arithmetic circuits with limited knowledge of computer arithmetic algorithms. The proposed EGG system can help to simplify and speed up the process of designing arithmetic circuits and can produce better solutions to the given problem.

Virtual Environment for Topographical Orientation (VETO): Clinical Rationale and Technical Characteristics

The lack of spatial orientation often serves as a warning light for a diffused cerebral impairment, such as the one at the origin of a confusional state or of a mental disorder. Topographical orientation disorders may be the expression of memory or attention deficits, unilateral spatial negligence, or elementary visuoperceptive disorders. In a minority of cases, spatial disorientation presents as an isolated disorder and is the expression of a focal brain lesion. The paper describes the clinical rationale and the technical characteristics of the Virtual Environment for Topographical Orientation (VETO). VETO is used both as a complementary tool for the assessment of topographical orientation disorders and to increase the possibilities of management of these patients from a rehabilitative point of view. VETO is based on the recent theoretical model of wayfinding in virtual environments proposed by Chen and Stanney (1999). This model suggests that wayfinders generally start from the direct perception of the environment or from the recall of a cognitive map. In terms of direct perception of the environment, landmark knowledge is acquired by directly viewing indirect representation such as photographs. In terms of cognitive mapping, procedure/route knowledge is acquired through direct experience or through simulated experience and stored in memory. Our hypothesis is that the study of spatial orientation through specific VETO tasks, both in normal samples and in subjects affected by topographical disorientation, can bring greater comprehension and validation of the cognitive models of spatial orientation present in literature.

Talking (across) Cultures

In this paper, I want to begin to contemplate the possibility that the concept of culture could one day be thought outside modern Western thought, via a reading of Martin Heidegger's 'Dialogue on Language between a Japanese and an Inquirer'. As we shall see, for Heidegger, the dominant position here is representationalism. And so a large part of what I want to do here is to begin to shake the concept of culture from these dominant representationalist moorings.

Indirect Representation and the Lando Principles. An Analysis of Some Problem Areas From the Perspective of English Law

The unpublished second report of the Lando Commission on The Principles of European Contract Law ('the Principles' or 'PECL') contains an important recent attempt to harmonise the laws of agency of European jurisdictions. Chapter 3 of the Principles deals with 'Authority of Agents'. Following the civil law model, Article 3:102 PECL distinguishes between direct and indirect representation. Direct representation exists where an agent acts 'in the name of' a principal (Art. 3:102(1) PECL). If the agent acts within the scope of his authority (real or apparent), his acts bind the principal and third party directly; the agent drops out. Indirect representation covers two types of case in which a principal enlists the assistance of an intermediary to act for him in transactions with third parties (Art. 3:102(2) PECL). The first can be termed 'undisclosed agency'. In these cases, the principal confers authority on the intermediary to create privity between him (the principal) and third parties. As it happens, however, the third party neither knows nor has reason to know that the intermediary acts as an agent. The second category of indirect representation can for convenience be termed 'commission agency'. In this case, by contrast, the principal does not confer authority on the intermediary to create privity of contract between him (the principal) and third parties. The intermediary is to act 'in his own name': he is to contract with third parties in a personal capacity. In both cases of indirect representation, intermediary and third party are bound to each other; principal and third party are not (Art. 3:301 PECL). Even so, in two situations the principal is entitled to exercise against the third party the rights that are acquired on his behalf by the intermediary: if the intermediary goes bankrupt or is guilty of a fundamental non-performance of his duties to the principal (Art. 3:302 PECL). The third party is entitled, in similar circumstances, to exercise against the principal the rights that the third party has against the intermediary (Art. 3:303 PECL).

Advective control of groundwater contaminant plumes: Model development and comparison to hydraulic control

A new optimization formulation for designing groundwater plume control systems is presented. The new formulation uses particle‐tracking techniques in a two‐step solution process. The two‐step procedure is motivated by numerical and computational considerations; particle representation is defined to take advantage of specific properties and improve model convergence. The optimization formulation seeks the least cost control system that satisfies the two equivalent requirements that the contaminant plume be located within the capture zone (step 1) and that all particles representing contaminant solute travel to an extraction well (step 2). To date, optimization formulations for plume capture design have emphasized either hydraulic or concentration control; however, these formulations provide indirect representation of the plume control and containment problem. The model presented here explicitly represents the capture zone design problem using particle tracking and formalizes the design procedures used by many practitioners. Two example problems representing two‐ and three‐dimensional flow systems are used to demonstrate the new advective control model. Hydraulic control formulations for the two problems are also developed, and designs are compared with those of the advective control model. Control systems resulting from the hydraulic control model are sensitive to constraint magnitude and location, highlighting the need for constraint calibration in order to best achieve design goals. Conversely, constraints in the new model directly represent the plume capture problem, and the model provides more efficient capture zone designs than the hydraulic control formulation.

Variational formulation using integral equations to solve sound scattering above an absorbing plane

The boundary element method is used to model two-dimensional acoustic radiation and scattering from a body of arbitrary shape above an infinite plane of flat surface and homogeneous impedance. The particularity of the study is the use of an indirect integral representation of the solution, given in terms of the jumps of pressure and its normal derivative through the boundaries. A variational formulation is associated with the boundary indirect integral equations modeling our problem. The major difficulty in the formulation is the infinite feature of the plane, which is avoided by introducing an appropriate Green’s function. Numerical results of the attenuation of sound by noise barriers are presented. They show good agreement with other results in the literature.