An analysis of the ex post Fisher hypothesis at short and long term

This paper tests the Fisher effect. The analysis is applied to the U.S.A. It contributes to the existing empirical literature in three ways. First, it considers a panel of short term and long term real interest rates between 1960 and 2008. Second, it explores both the presence of unit root and structural changes in real interest rates, by allowing for interaction between these two assumptions as suggested by the recent work of Lee and Strazicich. The third contribution consists in testing formally for the number of breaks using Bai and Perron (1998, 2003) test.Unit Root, Structural Break, Fisher Hypothesis, Cointegration

Hybrid CMS methods with model reduction for assembly of structures

Future on-orbit structures will be designed and built in several stages, each with specific control requirements. Therefore there must be a methodology which can predict the dynamic characteristics of the assembled structure, based on the dynamic characteristics of the subassemblies and their interfaces. The methodology developed by CSC to address this issue is Hybrid Component Mode Synthesis (HCMS). HCMS distinguishes itself from standard component mode synthesis algorithms in the following features: (1) it does not require the subcomponents to have displacement compatible models, which makes it ideal for analyzing the deployment of heterogeneous flexible multibody systems, (2) it incorporates a second-level model reduction scheme at the interface, which makes it much faster than other algorithms and therefore suitable for control purposes, and (3) it does answer specific questions such as 'how does the global fundamental frequency vary if I change the physical parameters of substructure k by a specified amount?'. Because it is based on an energy principle rather than displacement compatibility, this methodology can also help the designer to define an assembly process. Current and future efforts are devoted to applying the HCMS method to design and analyze docking and berthing procedures in orbital construction

Progressive construction of a parametric reduced-order model for PDE-constrained optimization

An adaptive approach to using reduced-order models as surrogates in PDE-constrained optimization is introduced that breaks the traditional offline-online framework of model order reduction. A sequence of optimization problems constrained by a given Reduced-Order Model (ROM) is defined with the goal of converging to the solution of a given PDE-constrained optimization problem. For each reduced optimization problem, the constraining ROM is trained from sampling the High-Dimensional Model (HDM) at the solution of some of the previous problems in the sequence. The reduced optimization problems are equipped with a nonlinear trust-region based on a residual error indicator to keep the optimization trajectory in a region of the parameter space where the ROM is accurate. A technique for incorporating sensitivities into a Reduced-Order Basis (ROB) is also presented, along with a methodology for computing sensitivities of the reduced-order model that minimizes the distance to the corresponding HDM sensitivity, in a suitable norm. The proposed reduced optimization framework is applied to subsonic aerodynamic shape optimization and shown to reduce the number of queries to the HDM by a factor of 4-5, compared to the optimization problem solved using only the HDM, with errors in the optimal solution far less than 0.1%

Downward Determination in Semiotic Multi-level Systems

Peirce's pragmatic notion of semiosis can be described in terms of a multi-level system of constraints involving chance, efficient, formal and final causation. According to the model proposed here, law-like regularities, which work as boundary conditions or organizational principles, have a downward effect on the spatiotemporal distribution of lower-level semiotic items. We treat this downward determinative influence as a propensity relation: if some lower-level entities a,b,c,-n are under the influence of a general organizational principle, W, they will show a tendency to behave in certain specific ways, and, thus, to instantiate a set of specific processes. Our goal in this paper is to examine the role of downward determination in semiotic systems, conceived as multi-level hierarchical systems

Federal Funds Rate Stationarity: New Evidence

This paper investigates the stationarity of the Federal Funds Rate. It contributes to the existing empirical literature in two ways. First, it explores both the presence of unit root and structural changes in the federal funds rate monthly data, by allowing for interaction between these two assumptions as suggested by the recent work of Lee and Strazicich. The second contribution consists in testing formally for the number of breaks. Using monthly data from January 1960 to April 2008, we find strong evidence in favor of a stationary process with two breaks. The two breaks identified correspond respectively to the first oil shock and to the change in the Fed operating procedure in the early eighties.

Migration and Education Decisions in a Dynamic General Equilibrium Framework

With growing international skilled labor mobility, education and migration decisions have become increasingly inter-related, and potentially have a large impact on the growth trajectories of source countries, through their effects on labor supply, savings, or the cost of education. The authors develop a generic dynamic general equilibrium model to analyze the education-migration nexus in a consistent framework. They use the model as a laboratory to test empirical conditions for the existence of net brain gain, that is, greater domestic accumulation of human capital (in per capita terms) with greater migration of skilled workers. The results suggest that although some structural parameters can favor simultaneously greater human capital accumulation and greater skilled migration --such as high ratio of remittances over domestic incomes, high dependency ratios in migrant households, low dependency ratios in source countries, increasing returns to scale in the education sector, technological transfers and export market access with Diasporas, and efficient financial markets -- this does not necessarily mean that greater migration encourages the constitution of greater stocks of human capital in source countries.Migration; Education; Brain Gain; Brain Drain; General Equilibrium Models