Theoretical Setup Research Articles

Taking Trends Seriously in DSGE Models: An Application to the Dutch Economy

We construct a new-Keynesian DSGE model tailored to the Netherlands and interpret it as a multivariate unobserved components model. We identify three major stochastic trends in the data — trends in general - purpose technology, investment-specific technology, and labor supply — and model them formally in our theoretical set-up. Our trend-cycle decomposition captures the data’s co-integrating properties without which long-run analysis — whether scenario analysis or forecasting — would likely be mis-specified. In particular, this approach appears to produce better-behaved posteriors for parameters along decision margins where traditional modeling imposes highly persistent but temporary shocks. The existence of permanent and temporary disturbances along the same margin broadens the scope for counter-factuals. Specifically, differences in short-run responses to the two types of shocks reflect smoothing motives and discounted valuation effects reminiscent of the Permanent Income Hypothesis.

Forecasting Nonlinear Aggregates and Aggregates with Time-varying Weights

Summary Despite the fact that many aggregates are nonlinear functions and the aggregation weights of many macroeconomic aggregates are time-varying, much of the literature on forecasting aggregates considers the case of linear aggregates with fixed, time-invariant aggregation weights. In this study a framework for nonlinear contemporaneous aggregation with possibly stochastic or time-varying weights is developed and different predictors for an aggregate are compared theoretically as well as with simulations. Two examples based on European unemployment and inflation series are used to illustrate the virtue of the theoretical setup and the forecasting results.

The Effects of Temporary Immigration on Prices of Non Traded Goods and Services

This paper analyzes the impact of temporary immigration on the prices of nontradable goods and services. It presents a model of a small open economy that produces two goods/services, one tradable and one non tradable. It is assumed that temporary immigrants are confined to work in the non-traded sector and that they are only imperfect substitutes for permanent immigrants and native low skill workers. In our theoretical set-up temporary immigration is predicted to have a negative effect on the prices of non-traded goods and services, while the effect of permanent immigrants depends on the relative low skill domestic labor intensity of the non tradable sector. We test these predictions empirically using a panel dataset of 14 U.S. cities for the period 2000-2006. In line with other recent empirical studies we find that both types of immigration have a negative impact on the relative price of non-tradable services as a whole. These findings confirm that immigration, like trade and offshoring, has the potential to increase welfare through the reduction of consumer and input prices. When distinguishing individual non tradable sectors, though, we find evidence that permanent immigration increases the price of transport and health services. This finding is in line with the predictions of earlier theoretical work and suggests in the context of our model that these sectors are less low skill domestic labor intensive than tradable goods and services.

Signature of a universal statistical description for drift-wave plasma turbulence

This letter provides a theoretical interpretation of numerically generated probability density functions (PDFs) of intermittent plasma transport events. Specifically, nonlinear gyrokinetic simulations of ion-temperature-gradient turbulence produce the time series of heat flux that manifestly exhibit non-Gaussian PDFs with enhanced tails. It is demonstrated that, after the removal of autocorrelations, the numerical PDFs can be matched with predictions from a fluid theoretical setup based on the instanton method. This result points to a universality in the modeling of intermittent stochastic process offering a predictive capability.

Sulfur Dioxide Production from Phosphogypsum: Thermodynamic Analysis and Experimental Results

Phosphogypsum or chemical gypsum is a by-product generated in the manufacture of phosphoric acid, generated in the proportion of 4 to 6 tons for every ton of acid produced by the fertilizer industry. Its reuse is important from the economic, social and environmental point of view. The purpose of this paper is to investigate the thermodynamic condition of sulfur dioxide recovering from thermal decomposition of phosphogypsum. The main advantage of this process is to return the sulfur dioxide to sulfuric acid manufacturing. In this case, sulfur demand by fertilizer industry and phosphogypsum generation could be greatly reduced. Experimental results were obtained from a lab scale rotary kiln. Theoretical approach and experimental setup were validated by using the actual data from thermal decomposition of limestone. Theoretical and experimental results showed the thermal decomposition of phosphogypsum is thermodynamically feasible only at high temperatures.

Erratum: NS-branes in five-dimensional brane world models [Phys. Rev. D82, 046001 (2010)

We study codimension-1 brane solutions of the 5d brane world models compactified on $S_1 / \mathbb{Z}_2$. In string theoretical setup they suggest that the background branes located at orbifold fixed points should be NS-branes (in the five dimensional sense), rather than D-branes. Indeed, the existence of the background NS-branes is indispensable to obtain flat geometry $M_4 \times S_1 / \mathbb{Z}_2$ where $M_4$ represents the 4d Minkowski spacetime, and without these branes the 5d metric becomes singular everywhere. This result is very reminiscent of the $(p+3)$d effective string theory \cite{1} where the NS-NS type $p$-brane is indispensable to obtain a flat geometry $R_2$ or $R_2 /\mathbb{Z}_n$ on the transverse dimensions. Without this NS-NS type $p$-brane the 2d transverse space becomes a pin-shaped singular space. The correspondence between these two theories leads us to a conjecture that the whole flat backgrounds of the string theory inherently invovle the NS-branes implicitly in their ansatz, and hence the true background $p$-branes immanent in our spacetime may be NS-branes, instead of D-branes. We argue that this result can have a significant consequence in the context of the cosmological constant problem.

NS-branes in five-dimensional brane world models

We study codimension-1 brane solutions of the five-dimensional brane world models compactified on ${S}_{1}/{\mathbb{Z}}_{2}$. In the string theoretical setup, they suggest that the background branes located at orbifold fixed points should be Neveu-Schwarz (NS)-branes (in the five-dimensional sense), rather than D-branes. Indeed, the existence of the background NS-branes is indispensable to obtain flat geometry ${M}_{4}\ifmmode\times\else\texttimes\fi{}{S}_{1}/{\mathbb{Z}}_{2}$, where ${M}_{4}$ represents the four-dimensional Minkowski spacetime, and without these branes the five-dimensional metric becomes singular everywhere. This result is very reminiscent of the ($p+3$)-dimensional effective string theory [8] where the NS-NS type $p$-brane is indispensable to obtain a flat geometry ${R}_{2}$ or ${R}_{2}/{\mathbb{Z}}_{n}$ on the transverse dimensions. Without this NS-NS type $p$-brane, the two-dimensional transverse space becomes a pin-shaped singular space. The correspondence between these two theories leads us to a conjecture that the whole flat backgrounds of the string theory inherently involve the NS-branes implicitly in their ansatz, and hence the true background $p$-branes immanent in our spacetime may be NS-branes, instead of D-branes. We argue that this result can have a significant consequence in the context of the cosmological constant problem.

An Approach to Masonry Structural Analysis by the No-Tension Assumption—Part I: Material Modeling, Theoretical Setup, and Closed Form Solutions

The prevalent feature that characterizes masonry structures and makes them dissimilar from modern reinforced concrete and steel structures is quite definitely their inability to resist tensile stresses. Therefore, it is natural that the material model that is intended to be an “analog” of real masonry cannot resist tensile stress but possibly behaves elastically under pure compression, opening a perspective on the adoption of the no-tension (NT) material constitutive assumption. Founded on the NT theory, the basic direction and aim of the present work is to propose a unified treatment of masonry structures presenting an overall and comprehensive up-to-date insight in the analysis of masonry constructions while providing basic and advanced concepts and tools already available or original. The note is intended to lead to several notable results including, just to mention some of the outcomes, that the St. Venant’s postulate does not hold in NT solids, no energy is dissipated by fracture, special accommodations for discontinuous loads are needed, and the relevant developments are provided, among other significant outcomes such as the identification of operative procedures for engineering solutions of structural problems. In the first part of the paper, the basics for the foundation of a NT material theory are illustrated, and the relevant principles for structural analysis, mainly identified in the classic energy theorems and suitably adapted to the material at hand, are formulated. In (apparently) simple cases, closed-form solutions can be obtained, or, at least, the solution process can be prepared after a preliminary screening of the equilibrium scenario. The application to two-dimensional no-tension elasticity is then illustrated in the last section, with reference to two sample cases. The first example proves that the solution in a NT panel acted on by vertical loads on the top is clearly identified in terms of stress, but if discontinuities are present in the load pattern, these reflect in some strong singularities in the deformation field that requires to deepen the problem. The second example is concerned with a NT-elastic half-plane, and a technique to find approximate solutions is outlined and carried on in detail. In Part II of the note, it is demonstrated that discontinuous or lumped load patterns can be looked at as frontier cases: They are not in contrast, but in some sense they are not natural to NT solids. Still in Part II, it is shown how the equilibrium problem can be managed both through the strain and the stress approach.

Forecasting Nonlinear Aggregates and Aggregates with Time-varying Weights

Despite the fact that many aggregates are nonlinear functions and the aggregation weights of many macroeconomic aggregates are time-varying, much of the literature on forecasting aggregates considers the case of linear aggregates with fixed, time-invariant aggregation weights. In this study a framework for nonlinear contemporaneous aggregation with possibly stochastic or time-varying weights is developed and different predictors for an aggregate are compared theoretically as well as with simulations. Two examples based on European unemployment and inflation series are used to illustrate the virtue of the theoretical setup and the forecasting results.

Soil moisture assessment by means of compressional and shear wave velocities: Theoretical analysis and experimental setup

In previous works, the authors presented the outline of a method for measuring the moisture content in agricultural soils via elastic waves, along with experimental results obtained on a specimen of sandy soil. This work illustrates other aspects and results of the research, regarding both the underlying theory and the design and realization of an improved measurement system. Firstly, the derivation of the simplified equations which are at the basis of the moisture measurement is thoroughly illustrated and discussed, starting from the more complex (and generally unmanageable) equations of elastic waves in unconsolidated porous media. The analysis suggests that by measuring the velocities of low-frequency compressional and shear waves in soils, it is possible not only to measure the water content, but also the uniformity in the water distribution. Secondly, the design and the practical realization of an experimental setup, which is able to measure the velocity of compressional and shear waves in soils, is illustrated in detail. The use of custom-built compressional and shear waves electromechanical actuators, together with geophones, low noise preamplifiers, and suitable signal processing techniques, brought to the realization of an effective and reasonably accurate measurement system.

Trend Inflation, Taylor Principle, and Indeterminacy

Positive trend inflation shrinks the determinacy region of a basic New Keynesian dynamic stochastic general equilibrium model when monetary policy is conducted by a contemporaneous interest rate rule. Neither the Taylor principle, which requires the inflation coefficient to be greater than one, nor the generalized Taylor principle, which requires that the nominal interest rate to be raised by more than the increase in inflation in the long run, is a sufficient condition for local determinacy of equilibrium. This finding holds for different types of Taylor rules, inertial policy rules, and price indexation schemes. Therefore, regardless of the theoretical setup, the monetary literature on interest rate rules cannot disregard average inflation in both theoretical and empirical analyses.

Auditory and visual 3D virtual reality therapy for chronic subjective tinnitus: theoretical framework

It is estimated that ~10% of the adult population in developed countries is affected by subjective tinnitus. Physiopathology of subjective tinnitus remains incompletely explained. Nevertheless, subjective tinnitus is thought to result from hyperactivity and neuroplastic reorganization of cortical and subcortical networks following acoustic deafferentation induced by cochlear or auditory nerve damage. Involvement of both auditory and non-auditory central nervous pathways explains the conscious perception of tinnitus and also the potentially incapacitating discomfort experienced by some patients (sound hypersensitivity, sleep disorders, attention deficit, anxiety or depression). These clinical patterns are similar to those observed in chronic pain following amputation where conditioning techniques using virtual reality have been shown both to be theoretically interesting and effectively useful. This analogy led us to develop an innovative setup with dedicated auditory and visual 3D virtual reality environments in which unilateral subjective tinnitus sufferers are given the possibility to voluntarily manipulate an auditory and visual image of their tinnitus (tinnitus avatar). By doing so, the patients will be able to transfer their subjective auditory perception to the tinnitus avatar and to gain agency on this multimodal virtual percept they hear, see and spatially control. Repeated sessions of such virtual reality immersions are then supposed to contribute to tinnitus treatment by promoting cerebral plasticity. This paper describes the theoretical framework and setup adjustments required by this very first attempt to adapt virtual reality techniques to subjective tinnitus treatment. Therapeutic usefulness will be validated by a further controlled clinical trial.

Flagging Standards: Globalization and Environmental, Safety, and Labor Regulations at Sea – By Elizabeth R. DeSombre

Flagging Standards: Globalization and Environmental, Safety, and Labor Regulations at Sea – By Elizabeth R. DeSombre

Flavor physics in the Randall-Sundrum model I. Theoretical setup and electroweak precision tests

A complete discussion of tree-level flavor-changing effects in the Randall-Sundrum (RS) model with brane-localized Higgs sector and bulk gauge and matter fields is presented. The bulk equations of motion for the gauge and fermion fields, supplemented by boundary conditions taking into account the couplings to the Higgs sector, are solved exactly. For gauge fields the Kaluza-Klein (KK) decomposition is performed in a covariant R_xi gauge. For fermions the mixing between different generations is included in a completely general way. The hierarchies observed in the fermion spectrum and the quark mixing matrix are explained naturally in terms of anarchic five-dimensional Yukawa matrices and wave-function overlap integrals. Detailed studies of the flavor-changing couplings of the Higgs boson and of gauge bosons and their KK excitations are performed, including in particular the couplings of the standard W and Z bosons. A careful analysis of electroweak precision observables including the S and T parameters and the Zbb couplings shows that the simplest RS model containing only Standard Model particles and their KK excitations is consistent with all experimental bounds for a KK scale as low as a few TeV, if one allows for a heavy Higgs boson and/or for an ultra-violet cutoff below the Planck scale. The study of flavor-changing effects includes analyses of the non-unitarity of the quark mixing matrix, anomalous right-handed couplings of the W bosons, tree-level flavor-changing neutral current couplings of the Z and Higgs bosons, the rare decays t-->c(u)+Z and t-->c(u)+h, and the flavor mixing among KK fermions. The results obtained in this work form the basis for general calculations of flavor-changing processes in the RS model and its extensions.

Stochastic Dynamics of Ferroelectric Polarization

This study is addressed to the conceptual and technical problems emerging for ferroelectric systems out of thermodynamic equilibrium. The theoretical setup includes a lattice of interacting cells, each cell obeying regular dynamics determined by Ginzburg-Landau model Hamiltonians whereas relaxation toward minimum energy state is reproduced by thermal environment. Representative examples include polarization response of a single lattice cell, birth of a domain as triggered by the ergodicity breaking, and the effect of nonlocal electroelastic interaction all evidenced combining the Fokker-Planck, imaginary time Schrödinger and symplectic integration techniques.

Commentary on the Special Issue

The past decade has seen resurgence of academic interest in international orga nizations (IOs) following th ir increas d prominence in international pol tics. This new wave of research on IOs has been largely theoretical?drawn from such diverse areas of institutional analysis as transaction cost analysis, bureaucratic theory, and game theory. Although it has improved our understanding of why institu tions matter, the editors of this volume argue that theoretical work has advanced more quickly than empirical work. Their framework chapter thus introduces the goal of the International Organizations Count project as providing a broad research approach that seeks to mold and sharpen theories about IOs by conducting systematic tests and refining analytic techniques (emphasis added; Hafner-Burton, von Stein, and Gartzke 2008 [this issue]). They have brought together an impressive set of researchers whose high-quality contributions will have salutary impact in promot ing this type of research. Systematic research is tall order that is hard to fill. As the editors and authors recognize, being quantitative does not make research systematic. In addition to care ful measurement and statistical work of the sort emphasized here, we need rigorous theory and an exploration of causal mechanisms and contextual effects that some times is best done qualitatively. While research often aspires to maximize all three dimensions?witness the proliferation of three-part projects that proceed from theo retical set-up through large-rc estimation to case study analysis?fully systematic research is difficult to accomplish even in book-length contributions. Broad and systematic work is more property of research traditions and communities. Indivi dual articles can usually contribute only systematic piece to the overall puzzle, and how they best do that depends heavily on the development of the other pieces of the puzzle. To understand the contribution of this new wave of systematic quantitative work on IOs, we must understand how it fits with existing theoretical and qualita tive work. Contrary to the presumption of the volume, we do not have fully articulated theoretical models of IOs to test; as result, quantitative work needs to be more exploratory and inductive in character. This has implications for how systematic empirical work should be conducted, for what we should expect from the individual articles, and for the relationship between different types of research on IOs. April 2008 326-333 ? 2008 Sage Publications 10.1177/0022002707313694 http://jcr.sagepub.com hosted at http://online.sagepub.com

Investigating the determinants of pretrial settlement rates: contingent versus non-contingent lawyers’ fees

In this article, we explore the possibility that the percentage of litigations settled outside of court is affected by the degree of contingency of lawyers’ fees. In our view, a litigation is a game where not only the plaintiff and the defendant, but also their lawyers are independent players. The main consequence of this assumption is that the authority to settle is allocated endogenously to either the clients or their lawyers, depending on the value of the relevant parameters. In this game theoretical setup, (1) we compare the incentives to settle provided by contingent and non-contingent lawyers’ fees, and (2) we state the conditions under which settlement is more likely to happen.

The political economy of investment: The case of pollution control technology

This paper seeks to explain the implications of corruption and political instability for firm investment in abatement technology. In our theoretical set-up, a firm has an incentive to under-invest in abatement technology in order to gain a political advantage. The prediction that emerges is that greater corruptibility increases the level of abatement technology investment. This occurs because the strategic incentive to under-invest in pollution control technology declines when policymakers become more corruptible. Moreover, the model predicts that political instability raises abatement technology investment. Using steel-sector panel data from 41 countries for the years 1992–1998, we find empirical support for these predictions.

A tabulated formulation of hyperelasticity with rate effects and damage

The simulation of rubber-like materials is usually based on hyperelasticity. If strain-rate dependency has to be considered viscous dampers also have to be taken into account in the rheological model. A disadvantage of such a description is time-consuming parameter identification associated with the damping constants. In this paper, a tabulated formulation is presented which allows the fast generation of input data based on uniaxial static and dynamic tensile tests at different strain rates. Unloading, i.e. forming a hysteresis loop, can also be modeled easily based on a damage formulation. We show the theoretical background and algorithmic setup of our model that has been implemented in the explicit finite element program LS-DYNA [1-3]. Apart from purely numerical examples, the validation of a soft and a hard rubber under loading and subsequent unloading at different strain rates is shown.

A field-theoretical approach to the spin glass transition: models with long but finiteinteraction range

We study spin glasses with the Kac-type interaction potential for small but finite inverse interactionrange γ. Using the theoretical set-up of coupled replicas, through the replica methodwe argue that the probability of overlap profiles can be expressed for smallγ through a large deviation functional. This result is supported by rigorous arguments,showing that the large deviation functional provides at least upper bounds for theprobability. Finally we analyse the rate function, in the vicinity of the critical pointTc = 1,h = 0 of mean field theory, and we study the free energy cost of overlap interfaces, assuming thevalidity of a gradient expansion for the rate functional.