Trade and Business-Cycle Comovement: Evidence from the EU

This paper is an empirical study of the determinants of business-cycle comovement. Using a panel of European countries (1972-2004) it is found that bilateral trade intensity is a robust determinant of real comovement in Europe, this confirming the seminal study by Frankel and Rose (1998). It is also found that convergence in macroeconomic policies (especially fiscal policies) is associated to high degree of intra-european business-cycle correlation. Moreover, having controlled for policy convergence, the effect of bilateral trade on business cycle comovement weakens on average by a factor of 36%-33% with respect to that estimated according to Frankel and Rose’s econometric specification, this suggesting the potential endogeneity of the set of instrumental variables adopted by the two authors (Gruben, Koo and Millis, 2002).

Essays on Nonlinear Macroeconomic Dynamics

This dissertation consists of four essays that study topics in macroeconomics, finance and their interplay using nonlinear quantitative equilibrium models and state of the art econometric techniques. Chapter 1 proposes a general equilibrium model with financial intermediation and sovereign default risk to study the macroeconomic consequences of news regarding a future sovereign default. The model, estimated on Italian data, is used to measure the output losses of the 2010-2012 sovereign debt crisis, and to evaluate the effects of credit policies implemented by European authorities. Chapter 2 proposes a new class of time series model that can be used to measure nonlinearities in the data and to evaluate the fit of Dynamic Stochastic General Equilibrium (DSGE) models solved with high order perturbation. We first characterize this class, the Quadratic Autoregressive (QAR) model. We then show how the QAR model can be used as a diagnostic tool to assess whether a DSGE model is able to replicate the nonlinear behavior of a set of U.S. aggregate time series. Chapter 3 studies the determinants of medium term movements in the market value of U.S. corporations. We find that secular movements in the mean and volatility of TFP growth are strongly associated with these medium term fluctuations in asset prices. These empirical findings are then interpreted within a production based asset pricing model where the mean and volatility of aggregate productivity growth varies over time. We show that the model can rationalize a sizable elasticity of asset prices to the drivers of aggregate productivity. Chapter 4 proposes a method to identify Harrod-neutral technology shocks in the data in presence of input heterogeneity in the aggregate production function. We prove that, in a wide class of models, Harrod-neutral technology shocks are the only one consistent with a certain form of balanced growth. We then use this property to identify Harrod-neutral shocks using a state-space model. Monte Carlo simulations show that the proposed method performs very well in small samples

Trade and business cycle co-movement: evidence from the EU

This paper studies empirically the determinants of business cycle co-movement using a panel of European countries (1972-2004). We find that both policy convergence (in particular fiscal policy) and bilateral trade intensity are robust determinants of real co-movement in Europe, this confirming the seminal study by Frankel and Rose (1998), and more recent finding by Bergman (2004) and Darvas, Rose and Svapary (2005). Moreover ,once controlling for policy convergence, the effect of bilateral trade on business cycle co-movement weakens by a factor of 36%-33%. This finding is interpreted as being evidence in favour of the recent claim by Gruben, Koo and Millis (2002) that Frankel and Rose econometric procedure suffers from omitted variables bias and endogeneity in the set of instruments

Smart engineering of various enzymes for asymmetric synthesis of chiral molecules on industrial scale

The commercialization of sustainable enzymatic and microbial catalysis technology is gaining increasing priority for the synthesis of chiral compounds from achiral precursors that require high selectivity and high substrate load. Thus, the fast and cost-effective development of novel biocatalytic processes using an integrated platform offers significant opportunities to fine chemical, pharmaceutical, food & feed, material and related industries. Please click Additional Files below to see the full abstract

Sustainable biocatalytic synthesis of β-hydroxyl-α-amino acids on an industrial scale

The development and commercialization of sustainable enzymatic and microbial catalysis technologies is gaining increasing priority to reduce the environmental impact of chemical and related industries. Enzymes offer, as common platform, significant opportunities for innovations to enhance production capabilities to meet these new reduced impact demands, whilst retaining product quality and keeping costs down. To enable cost efficient biocatalytic processes, however, high selectivity, high activity, high substrate loadings and tolerance to organic solvents are required. This is in general not sufficiently displayed by natural enzymes, despite providing high selectivity and activity on native substrates under physiological conditions. As a solution, enzyme engineering allows us to optimize any enzyme to a powerful catalyst that overcomes these boundaries and can be conveniently applied under industrial conditions. As an industrial example, we will discuss the synthesis of β-hydroxyl-α-amino acids, important chiral building blocks in pharmaceutical and fine chemical industry. Current chemical synthesis protocols employ hazardous and environmentally unfriendly methods, thus, a replacement by safe and green biocatalysis is desired. However, wild type aldolases do not meet the anticipated target criteria for selectivity, activity and solvent tolerance under process conditions. Nonetheless, smart bioinformatics guided directed evolution, enabled us to develop an enzyme variant which meets the industrial target for the sustainable (βR)-β-Hydroxy-4-nitro-L-phenylalanine production at multi ton scale, which is a precursor for chloramphenicol. Remarkably, this new synthetic route to chloramphenicol, enabled by our engineered aldolase, is 5 steps shorter than the traditional chemical route, avoiding the use of various hazardous and environmentally unfriendly reactants. Please click Additional Files below to see the full abstract

Wide-field compensation of monochromatic eye aberrations: expected performance and design trade-offs

Contiene: fórmulas y 6 ilustraciones.The optical quality of the human eye varies across the visual field. Hence an exact compensation of the eye aberration for a given field point can give rise to a less-than-optimum compensation in neighboring field regions. We have studied some aspects of this problem and present here an approach to design wide-field (,10°) optically thin correcting elements, e.g., phase plates, deformable mirrors, and liquid-crystal displays. Their expected performance is assessed using actual eye aberration data. Particular attention is given to the design of elements providing a minimum averaged rms residual aberration and those providing a nearly uniform rms residual aberration across a given field.Work supported by the Spanish Ministerio de Ciencia y Tecnología, Plan Nacional de Investigación Científica, Desarrollo e Innovación Tecnológica (I 1 D 1 I), DPI2002-04370-C02. - This paper was published in Journal of the Optical Society of America A, and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/abstract.cfm?URI=josaa-20-1-1. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.Peer reviewe

CaLB Catalyzed Conversion of ε-Caprolactone in Aqueous Medium. Part 1: Immobilization of CaLB to Microgels

The enzymatic ring-opening polymerization of lactones is a method of increasing interest for the synthesis of biodegradable and biocompatible polymers. In the past it was shown that immobilization of Candida antarctica lipase B (CaLB) and the reaction medium play an important role in the polymerization ability especially of medium ring size lactones like ε-caprolactone (ε-CL). We investigated a route for the preparation of compartmentalized microgels based on poly(glycidol) in which CaLB was immobilized to increase its esterification ability. To find the ideal environment for CaLB, we investigated the acceptable water concentration and the accessibility for the monomer in model polymerizations in toluene and analyzed the obtained oligomers/polymers by NMR and SEC. We observed a sufficient accessibility for ε-CL to a toluene like hydrophobic phase imitating a hydrophobic microgel. Comparing free CaLB and Novozym® 435 we found that not the monomer concentration but rather the solubility of the enzyme, as well as the water concentration, strongly influences the equilibrium of esterification and hydrolysis. On the basis of these investigations, microgels of different polarity were prepared and successfully loaded with CaLB by physical entrapment. By comparison of immobilized and free CaLB, we demonstrated an effect of the hydrophobicity of the microenvironment of CaLB on its enzymatic activity

In silico screening of transaminase using semi-empirical QM/MM approach

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TransCent: Computational enzyme design by transferring active sites and considering constraints relevant for catalysis

BACKGROUND: Computational enzyme design is far from being applicable for the general case. Due to computational complexity and limited knowledge of the structure-function interplay, heuristic methods have to be used. RESULTS: We have developed TransCent, a computational enzyme design method supporting the transfer of active sites from one enzyme to an alternative scaffold. In an optimization process, it balances requirements originating from four constraints. These are 1) protein stability, 2) ligand binding, 3) pKa values of active site residues, and 4) structural features of the active site. Each constraint is handled by an individual software module. Modules processing the first three constraints are based on state-of-the-art concepts, i.e. RosettaDesign, DrugScore, and PROPKA. To account for the fourth constraint, knowledge-based potentials are utilized. The contribution of modules to the performance of TransCent was evaluated by means of a recapitulation test. The redesign of oxidoreductase cytochrome P450 was analyzed in detail. As a first application, we present and discuss models for the transfer of active sites in enzymes sharing the frequently encountered triosephosphate isomerase fold. CONCLUSION: A recapitulation test on native enzymes showed that TransCent proposes active sites that resemble the native enzyme more than those generated by RosettaDesign alone. Additional tests demonstrated that each module contributes to the overall performance in a statistically significant manner