Net Exports, Consumption Volatility and International Real Business Cycle Models

Conventional two-country RBC models interpret countercyclical net exports as reflecting, in large part, the dynamics of capital. I show that, quantitatively, theoretical economies rely on counterfactual terms of trade effects: trade fluctuations, on the contrary, are driven primarily by consumption smoothing, thus generating procyclical net trade in goods. I then consider a class of preferences that embeds home production in a reduced form: consumption volatility increases so that countercyclical net exports reflect primarily a strong relation between import of goods and income, as in the data. The major discrepancy between theory and data concerns the variability of international prices.Net exports; Home production; Consumption volatility.

Work and taxes: allocation of time in OECD countries

Policymakers devote a great deal of attention to short-run fluctuations in the labor market. Central banks monitor indicators of labor market tightness in the conduct of monetary policy due to the potential implications for inflation. And fiscal authorities are concerned with the budget consequences of fluctuations in the labor market because they affect both revenues and expenditure programs. More generally, these fluctuations may be associated with significant losses in welfare. ; This article stems from a striking empirical observation about long-run variations in labor market outcomes: Long-run changes in total hours of work in OECD countries exceed the variation of hours worked over the business cycle in a representative country (say, the United States) by almost an order of magnitude. If understanding changes in hours of work of the magnitude of business cycle fluctuations is an important policy concern, then understanding the sources of these trend differences is also crucial. Surprisingly, the academic and policy debates have focused on the business cycle movements in the labor market, almost ignoring low frequency changes. ; Lee Ohanian, Andrea Raffo, and Richard Rogerson describe the steep decline in average hours worked and the large variation across countries in the magnitude of this decline. Next, they find that changes in labor taxes account for a large share of the trend differences. Finally, they find that countries with high tax rates devote less time to market work, but more time to home activities, such as cooking and cleaning. Moreover, this reallocation of time from market work to home work is much stronger for females than for males.Taxation ; Labor market ; Hours of labor

Long-Term Changes in Labor Supply and Taxes: Evidence from OECD Countries, 1956-2004

We document large differences in trend changes in hours worked across OECD countries over the period 1956-2004. We then assess the extent to which these changes are consistent with the intratemporal first order condition from the neoclassical growth model. We find large and trending deviations from this condition, and that the model can account for virtually none of the changes in hours worked. We then extend the model to incorporate observed changes in taxes. Our findings suggest that taxes can account for much of the variation in hours worked both over time and across countries.

Reverse engineering of CAD models via clustering and approximate implicitization

In applications like computer aided design, geometric models are often represented numerically as polynomial splines or NURBS, even when they originate from primitive geometry. For purposes such as redesign and isogeometric analysis, it is of interest to extract information about the underlying geometry through reverse engineering. In this work we develop a novel method to determine these primitive shapes by combining clustering analysis with approximate implicitization. The proposed method is automatic and can recover algebraic hypersurfaces of any degree in any dimension. In exact arithmetic, the algorithm returns exact results. All the required parameters, such as the implicit degree of the patches and the number of clusters of the model, are inferred using numerical approaches in order to obtain an algorithm that requires as little manual input as possible. The effectiveness, efficiency and robustness of the method are shown both in a theoretical analysis and in numerical examples implemented in Python

Net exports, consumption volatility, and international real business cycle models

Conventional two-country RBC models interpret countercyclical net exports as reflecting, in large part, the dynamics of capital. I show that, quantitatively, theoretical economies rely on counterfactual terms of trade effects: trade fluctuations, on the contrary, are driven primarily by consumption smoothing, thus generating procyclical net trade in goods. I then consider a class of preferences that embeds home production in a reduced form: consumption volatility increases so that countercyclical net exports reflect primarily a strong relation between income and imports, as in the data. The major discrepancy between theory and data concerns the variability of international prices.Business cycles ; Exports

Data-driven quasi-interpolant spline surfaces for point cloud approximation

In this paper we investigate a local surface approximation, the Weighted Quasi Interpolant Spline Approximation (wQISA), specifically designed for large and noisy point clouds. We briefly describe the properties of the wQISA representation and introduce a novel data-driven implementation, which combines prediction capability and complexity efficiency. We provide an extended comparative analysis with other continuous approximations on real data, including different types of surfaces and levels of noise, such as 3D models, terrain data and digital environmental data

Weighted Quasi Interpolant Spline Approximations: Properties and Applications

Continuous representations are fundamental for modeling sampled data and performing computations and numerical simulations directly on the model or its elements. To effectively and efficiently address the approximation of point clouds we propose the Weighted Quasi Interpolant Spline Approximation method (wQISA). We provide global and local bounds of the method and discuss how it still preserves the shape properties of the classical quasi-interpolation scheme. This approach is particularly useful when the data noise can be represented as a probabilistic distribution: from the point of view of nonparametric regression, the wQISA estimator is robust to random perturbations, such as noise and outliers. Finally, we show the effectiveness of the method with several numerical simulations on real data, including curve fitting on images, surface approximation and simulation of rainfall precipitations

Uso de mallas antigranizo en fruticultura

Análisis climático de los eventos de granizadas en los Valles de la Norpatagonia. Con el objetivo de visualizar tendencias en la frecuencia de caída de granizo e identificar las zonas más afectadas asociadas a los procesos de variabilidad y cambio climático, el INTA Alto Valle realizó un análisis climático sobre la caída de granizo para 24 localidades de nuestra región, con un total de 37 años de registro. Para ver las zonas de mayor riesgo y la tendencia de ocurrencias, se analizó la variabilidad espacial, temporal y estacional de esta adversidad (Rodríguez y Muñoz, 2017).EEA Alto ValleFil: Raffo Benegas, María Dolores. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Alto Valle; ArgentinaFil: Rodríguez, Andrea Betiana. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Alto Valle; Argentin

Chanalyzer : a computational geometry approach for the analysis of protein channel shape and dynamics

Morphological analysis of protein channels is a key step for a thorough understanding of their biological function and mechanism. In this respect, molecular dynamics (MD) is a very powerful tool, enabling the description of relevant biological events at the atomic level, which might elude experimental observations, and pointing to the molecular determinants thereof. In this work, we present a computational geometry-based approach for the characterization of the shape and dynamics of biological ion channels or pores to be used in combination with MD trajectories. This technique relies on the earliest works of Edelsbrunner and on the NanoShaper software, which makes use of the alpha shape theory to build the solvent-excluded surface of a molecular system in an aqueous solution. In this framework, a channel can be simply defined as a cavity with two entrances on the opposite sides of a molecule. Morphological characterization, which includes identification of the main axis, the corresponding local radius, and the detailed description of the global shape of the cavity, is integrated with a physico-chemical description of the surface facing the pore lumen. Remarkably, the possible existence or temporary appearance of fenestrations from the channel interior towards the outer lipid matrix is also accounted for. As a test case, we applied the present approach to the analysis of an engineered protein channel, the mechanosensitive channel of large conductance

Accurate pHEMT nonlinear modeling in the presence of low-frequency dispersive effects

Low-frequency (LF) dispersive phenomena due to device self-heating and/or the presence of "traps" (i.e., surface state densities and bulk spurious energy levels) must be taken into account in the large-signal dynamic modeling of III-V field-effect transistors when accurate performance predictions are pursued, since these effects cause important deviations between direct current (dc) and dynamic drain current characteristics. In this paper, a new model for the accurate characterization of these phenomena above their cutoff frequencies is presented, which is able to fully exploit, in the identification phase, large-signal current-voltage (I-V) measurements carried out under quasi-sinusoidal regime using a recently proposed setup. Detailed experimental results for model validation under LF small- and large-signal operating conditions are provided. Furthermore, the I-V model proposed has been embedded into a microwave large-signal pseudomorphic high electron-mobility transistor (pHEMT) model in order to point out the strong influence of LF modeling on the degree of accuracy achievable under millimeter-wave nonlinear operation. Large-signal experimental validation at microwave frequencies is provided for the model proposed, by showing the excellent intermodulation distortion (IMD) predictions obtained with different loads despite the very low power level of IMD products involved. Details on the millimeter-wave IMD measurement setup are also provided. Finally, IMD measurements and simulations on a Ka-band highly linear power amplifier, designed by Ericsson using the Triquint GaAs 0.25-/spl mu/m pHEMT process, are shown for further model validation