Macroeconomic consequences of global endogenous migration: a general equilibrium analysis

In this paper, we analyze the consequences of endogenous migration flows over the coming decades in a dynamic general equilibrium model of the world economy. Such an approach has two major benefits. First, it offers a global perspective on the economic consequences of international migration flows by taking into account effects on both the destination and the origin regions. Second, by allowing migration flows to be related to economic fundamentals, they are determined endogenously in the model. We proceed by estimating the determinants of migration in an econometric model and then endogenizing migration flows by introducing the estimated relationships between demographic and income developments in our world model. We show that (i) migration could have a substantial impact on GDP growth in sending and destination regions; (ii) endogenizing migration induces important changes in the volume and the distribution of migration flows between regions compared to the United-Nations projections; (iii) the size of these flows, although substantial, will not be sufficient to counteract the impact of population ageing in the receiving regions.CGEM, Migration, International capital flows.

Cognitive beamforming design for dual-function radar-communications

This paper introduces a dual-function radar-communication (DFRC) system with cognitive radio capability to tackle the spectral scarcity problem in wireless communications. Particularly, a cognitive DFRC system operates on a spectrum owned by a primary system to simultaneously perform data communication and target tracking while maintaining its interference to the primary users (PUs) below a certain threshold. To achieve this, an optimization problem is formulated to jointly design the beamforming vectors for both the radar and communication functions in minimizing the mean square error (MSE) of the beam patterns between the designed and desired waveforms under three constraints: i) the signal-to-interference-plus-noise ratio (SINR) at each data communication user; ii) the per-antenna transmit power; and iii) the interference imposed on each PU. The semidefinite relaxation technique is utilized to search for the optimal solution to the optimization problem. The simulation results indicate that our proposed cognitive DFRC approach can effectively protect the PUs while simultaneously perform its communication and radar functions

Metallicity Evolution in the Early Universe

Observations of the damped Lya systems provide direct measurements on the chemical enrichment history of neutral gas in the early universe. In this Letter, we present new measurements for four damped Lya systems at high redshift. Combining these data with [Fe/H] values culled from the literature, we investigate the metallicity evolution of the universe from z~1.5-4.5. Contrary to our expectations and the predictions of essentially every chemical evolution model, the N(HI)-weighted mean [Fe/H] metallicity exhibits minimal evolution over this epoch. For the individual systems, we report tentative evidence for an evolution in the unweighted [Fe/H] mean and the scatter in [Fe/H] with the higher redshift systems showing lower scatter and lower typical [Fe/H] values. We also note that no damped Lya system has [Fe/H] < -2.7 dex. Finally, we discuss the potential impact of small number statistics and dust on our conclusions and consider the implications of these results on chemical evolution in the early universe.Comment: 6 pages, 2 encapsulated figures, Latex2e, uses emulateapj.sty and onecolfloat.sty. Accepted for publication in ApJ Letters: Feb 28, 200

Potential for ultrafast dynamic chemical imaging with few-cycle infrared lasers

We studied the photoelectron spectra generated by an intense few-cycle infrared laser pulse. By focusing on the angular distributions of the back rescattered high energy photoelectrons, we show that accurate differential elastic scattering cross sections of the target ion by free electrons can be extracted. Since the incident direction and the energy of the free electrons can be easily changed by manipulating the laser's polarization, intensity, and wavelength, these extracted elastic scattering cross sections, in combination with more advanced inversion algorithms, may be used to reconstruct the effective single-scattering potential of the molecule, thus opening up the possibility of using few-cycle infrared lasers as powerful table-top tools for imaging chemical and biological transformations, with the desired unprecedented temporal and spatial resolutions.Comment: 16 pages, 6 figure

Resolution in Linguistic Propositional Logic based on Linear Symmetrical Hedge Algebra

The paper introduces a propositional linguistic logic that serves as the basis for automated uncertain reasoning with linguistic information. First, we build a linguistic logic system with truth value domain based on a linear symmetrical hedge algebra. Then, we consider G\"{o}del's t-norm and t-conorm to define the logical connectives for our logic. Next, we present a resolution inference rule, in which two clauses having contradictory linguistic truth values can be resolved. We also give the concept of reliability in order to capture the approximative nature of the resolution inference rule. Finally, we propose a resolution procedure with the maximal reliability.Comment: KSE 2013 conferenc

Bicritical and tetracritical phenomena and scaling properties of the SO(5) theory

By large scale Monte Carlo simulations it is shown that the stable fixed point of the SO(5) theory is either bicritical or tetracritical depending on the effective interaction between the antiferromagnetism and superconductivity orders. There are no fluctuation-induced first-order transitions suggested by epsilon expansions. Bicritical and tetracritical scaling functions are derived for the first time and critical exponents are evaluated with high accuracy. Suggestions on experiments are given.Comment: 11 pages, 8 postscript figures, Revtex, revised versio

Kinetic description of charmonium production in high-energy nuclear collisions

We study the evolution of charmonia as they collide with the constituents of the fireball produced in high-energy nucleus-nucleus collisions. The latter evolves in a manner controlled by the equation of state as given by lattice QCD, and is constructed in such a way that the observed hadronic spectra are correctly reproduced. A kinetic description of charmonium interactions with both quark-gluon and hadronic degrees of freedom allows to study in detail the evolution in different regimes, controlled by collision energy, kinematics and geometry. The data collected at the CERN-SPS accelerator are well described and new estimates for J/psi production at BNL-RHIC are presented.Comment: 19 pages, LaTeX, 13 .eps figure

Further development and validation of CO2FOAM for the atmospheric dispersion of accidental releases from carbon dioxide pipelines

This paper reports on the further development and validation of CO2FOAM, a dedicated computational fluid dynamics solver for the atmospheric dispersion of Carbon Dioxide (CO2) from accidental pipeline releases. The code has been developed within the framework of the open source CFD code OpenFOAM® (OpenCFD, 2014). Its earlier version used the homogeneous equilibrium method for fully compressible two-phase flow. Validation of the code against CO2 releases through vertical vent pipes and horizontal shock tubes was previously reported by Wen et al. (2013). In the present study, the homogeneous relaxation model has been implemented as it is more suited to account for the presence of solid CO2 within the releases. For validation, the enhanced CO2FOAM has been used to predict CO2 dispersion in a range of full scale tests within the dense phase CO2 PipeLine TRANSportation (COOLTRANS) research programme (Cooper, 2012) funded by National Grid. The test case used in the present study involved a puncture in a buried pipe. The experimental measurements were supplied to the authors after the predictions were completed and submitted to National Grid. Hence, the validation reported here is indeed ‘blind’. The validated model has also been used to study the effect of a commercial building located downstream from the release location