Флуктуационно-диссипативная теорема и частотные моменты функций реакции плотной плазмы на электромагнитное поле

The fluctuation-dissipative theorem and frequency moments for quadratic functions of the reaction of a dense plasma in a constant magnetic field to an electromagnetic field are considered. The frequency moments of the corresponding correlation functions are studied. A model approach is proposed to calculate quadratic reaction functions that determine nonlinear phenomena caused by the quadratic interaction of electromagnetic waves in a dense charged medium (Coulomb systems, plasma) in a constant magnetic field. Keywords: dense plasma, nonlinear fluctuation-dissipative theorem, quadratic reaction functions, nonlinear phenomena.

The estimation of reaction functions under tax competition

Most of the empirical literature on tax competition has been using panel models in which each country’s tax rate responds to a weighted average of other countries’ tax rates, where weights are given. This approach imposes the reaction functions to be such that all tax rates are either strategic complements or strategic substitutes for all the countries. Moreover, it also requires that the intensity of the reactions of the countries to be proportional to the same set of given weights. Since no theoretical model relies on such restrictive assumptions, we regain flexibility in the empirical analysis by using Vector Autoregressive (VAR) models, where the sign and intensity of countries’ reactions may be heterogeneous. Using a Monte Carlo exercise, we show that if the objects of interest are the reactions to shocks in the tax rates of the other countries and there is no a priori knowledge of the structure of the economy, it can be convenient to opt for a VAR rather than a panel setup. A Bayesian VAR model on real data shows that strategic complementarity between some countries may co-exist with strategic substitutability between other countries, a finding with potential policy implications on the debate on tax competition.

Universally valid reduction of multiscale stochastic biochemical systems using simple non-elementary propensities

Biochemical systems consist of numerous elementary reactions governed by the law of mass action. However, experimentally characterizing all the elementary reactions is nearly impossible. Thus, over a century, their deterministic models that typically contain rapid reversible bindings have been simplified with non-elementary reaction functions (e.g., Michaelis-Menten and Morrison equations). Although the non-elementary reaction functions are derived by applying the quasi-steady-state approximation (QSSA) to deterministic systems, they have also been widely used to derive propensities for stochastic simulations due to computational efficiency and simplicity. However, the validity condition for this heuristic approach has not been identified even for the reversible binding between molecules, such as protein-DNA, enzyme-substrate, and receptor-ligand, which is the basis for living cells. Here, we find that the non-elementary propensities based on the deterministic total QSSA can accurately capture the stochastic dynamics of the reversible binding in general. However, serious errors occur when reactant molecules with similar levels tightly bind, unlike deterministic systems. In that case, the non-elementary propensities distort the stochastic dynamics of a bistable switch in the cell cycle and an oscillator in the circadian clock. Accordingly, we derive alternative non-elementary propensities with the stochastic low-state QSSA, developed in this study. This provides a universally valid framework for simplifying multiscale stochastic biochemical systems with rapid reversible bindings, critical for efficient stochastic simulations of cell signaling and gene regulation. To facilitate the framework, we provide a user-friendly open-source computational package, ASSISTER, that automatically performs the present framework.

Fiscal reaction functions for the advanced economies revisited

We revisit the relationship between the primary balances/GDP and debt/GDP ratios (fiscal reaction function, FRF), in the advanced economies, showing that using adequate tests and estimators leads to question the validity of the current consensus. Using data for 1961–2019, we find that long-run FRFs exist only in a small number of advanced economies (Belgium, Germany, Greece, Norway, Portugal and Sweden), with polynomial effects with fiscal fatigue only in Germany. These results warn against the widespread practice of estimating homogeneous polynomial panel FRFs. Limiting the sample to 1961–2007, thus excluding the 2008 crisis and its aftermath, FRFs hold also in Canada, Ireland, Italy (polynomial), Spain and USA, though not in Germany, and the coefficients are generally larger. Particularly, after 2008 European Union countries appear somehow to have been more likely to implement FRFs.

Universally valid reduction of multiscale stochastic biochemical systems using simple non-elementary propensities

Biochemical systems consist of numerous elementary reactions governed by the law of mass action. However, experimentally characterizing all the elementary reactions is nearly impossible. Thus, over a century, their deterministic models that typically contain rapid reversible bindings have been simplified with non-elementary reaction functions (e.g., Michaelis-Menten and Morrison equations). Although the non-elementary functions are derived by applying the quasi-steady-state approximation(QSSA) to deterministic systems, they have also been widely used to derive propensities for stochastic simulations due to computational efficiency and simplicity. However, the validity condition for this heuristic approach has not been identified even for the reversible binding between molecules, such as protein-DNA, enzyme-substrate, and receptor-ligand, which is the basis for living cells. Here, we find that the non-elementary propensities based on the deterministic total QSSA can accurately capture the stochastic dynamics of the reversible binding in general. However, serious errors occur when reactant molecules with similar levels tightly bind, unlike deterministic systems.In that case, the non-elementary propensities distort the stochastic dynamics of a bistable switch in the cell cycle and an oscillator in the circadian clock. Accordingly, we derive alternative non-elementary propensities with the stochastic low-state QSSA,developed in this study. This provides a universally valid framework for simplifying multiscale stochastic biochemical systems with rapid reversible bindings, critical for efficient stochastic simulations of cell signaling and gene regulation.

A modality selective effect of functional laterality in pain detection sensitivity

The ability to detect environmental changes is essential to determine the appropriate reaction when facing potential threats. Both detection and reaction functions are critical to survival, and the superior performance of motor reaction for the dominant hand is well recognized in humans. However, it is not clear whether there exists laterality in sensitivity to detect external changes and whether the possible laterality is associated with sensory modality and stimulus intensity. Here, we tested whether the perceptual sensitivity and electrophysiological responses elicited by graded sensory stimuli (i.e., nociceptive somatosensory, non-nociceptive somatosensory, auditory, and visual) that were delivered on/near the left and right hands would be different for right-handed individuals. We observed that perceived intensities and most brain responses were significantly larger when nociceptive stimuli were delivered to the left side (i.e., the non-dominant hand) than to the right side (i.e., the dominant hand). No significant difference was observed between the two sides for other modalities. The higher sensitivity to detect nociceptive stimuli for the non-dominant hand would be important to provide a prompt reaction to noxious events, thus compensating for its worse motor performance. This laterality phenomenon should be considered when designing experiments for pain laboratory studies and evaluating regional sensory abnormalities for pain patients.

Institutions and Cyclicality of the Fiscal and Monetary Policies in Brazil

This paper investigates the relationship between the quality of institutions and the cyclical properties of macroeconomic policies in the Brazilian economy in the recent period. We extend the monetary and fiscal policy rules proposed by Taylor (2000) to incorporate a proxy for institutional quality. In the empirical analysis, we estimate reaction functions for monetary and fiscal policies by the Markov-Switching method. This methodology allows us to analyze how changes in the quality of institutions might influence the guidance of the fiscal and monetary policies over the sample period. The major results maintain that both monetary and fiscal policies are significantly countercyclical in periods that exhibit higher levels of institutional quality and are pro-cyclical or acyclical in periods which exhibit lower levels of institutional quality. Thus, the quality of institutions plays a key role in the government's ability to implement countercyclical monetary and fiscal policies to stabilize the Brazilian economy over the business cycle.

Determinants of fiscal effort in sub-Saharan African countries: Does conflict matter?

This study investigates the determinants of fiscal effort in sub-Saharan African (SSA) within the framework of fiscal reaction functions. Whereas previous studies focusing on SSA have mainly considered the economic non-debt determinants this study accounts for the role of conflict given its persistence in many SSA countries. It employs a variety of panel econometric methods that are applicable in tackling the problem of endogeneity. Specifically the study employs the instrumental variables fixed effects, the two-step generalised method of moments (GMM) and the traditional two-stage least squares techniques. Mainly the evidence shows that although SSA governments have made fiscal adjustments in response to the escalating levels of debt, conflict impacts negatively on this response in SSA. Furthermore, the results affirm the presence of fiscal fatigue in SSA’s fiscal reaction function. Recommendations based on these findings are discussed.

Accounting for adaptation and its effectiveness in International Environmental Agreements

This paper analyses, within a standard International Environmental Agreement game, the effect of the introduction of adaptation on climate negotiation. The model expands the existing literature by considering a double relation between the two strategies. The common assumption that higher mitigation decreases the marginal benefit of adaptation and vice versa is enriched allowing for the possibility that mitigation, leading to lower and more manageable damages, determines a greater effectiveness of adaptive measures. We find the possibility for adaptation and mitigation to be strategic complements and not, as commonly believed, substitutes. Yet, as already known from the literature, the presence of adaptation can determine upward-sloping mitigation reaction functions regardless of the strategic relationship between mitigation and adaptation. When this is the case, the grand coalition can form. Nonetheless, large participation can induce substantive welfare gains only if adaptation and mitigation are strategic complements.