Firms’ location Under taste and demand heterogeneity

In this paper we build a quality-augmented version of an economic geography model where consumers have heterogenous tastes for a set of manufacturing varieties. We discuss a footloose capital model and a footloose entrepreneur model. We show that firms selling the goods with higher values select the region hosting the largest number of consumers. Larger countries thus get better access to the higher quality products. We also show that the effect of spatial selection on firms' spatial distribution crucially depends on the properties of the taste distribution across varieties. Finally, we show that taste heterogeneity smooths the agglomeration patterns but that it should be considered neither as a dispersion force nor as an agglomeration force. Indeed, the introduction of taste heterogeneity makes an initially dispersed economy less dispersed and an initially agglomerated economy less agglomerated.heterogeneous taste and quality, spatial selection, economic geography, agglomeration, home market effect.

An Econometric Analysis of Trade Diversion under NAFTA

We provide an econometric analysis of whether or not the tariff preferences extended to Canada and Mexico under NAFTA may have resulted in trade diversion. A review of previous studies, both descriptive and econometric, suggests that trade diversion has occurred especially as evidenced by Mexico's increased shares of U.S. imports apparently at the expense of several Asian countries. We use a conceptual framework based on a partial-equilibrium model of differentiated product industries under monopolistic competition for many countries. The model is implemented empirically using a fixed-effect panel analysis of U.S. imports at the Harmonized System (HS) 2-digit level for the period, 1992-98. Of the 70 sets of regressions that were run, the coefficients of the tariff rates were statistically significant in 15 cases. The strongest evidence of trade diversion was found mainly for U.S. imports of textile and apparel products. We also estimated regressions for selected commodities at the HS 4-digit level. The results suggest trade diversion for textiles, apparel, and some footwear products but not for trade in motor cars and vehicles and television receivers, which may have been more influenced by changes in foreign direct investment and outsourcing rather than tariff preferences.

The spatial selection of heterogeneous firms

The aim of this paper is to study the spatial selection of firms once it is recognized that heterogeneous firms typically choose different locations in respond to market integration of regions having different sizes. Specifically, we show that decreasing trade costs leads to the gradual agglomeration of efficient firms in the large region because these firms are able to survive in a more competitive environment. In contrast, high-cost firms seek protection against competition from the efficient firms by establishing themselves in the small region. However, when the spatial separation of markets ceases to be a sufficient protection against competition from the low-cost firms, high-cost firms also choose to set up in the larger market where they have access to a bigger pool of consumers. This leads to the following prediction: the relationship between economic integration and interregional productivity differences first increases and then decreases with market integration.Firm heterogeneity, Spatial selection, Trade liberalization

Electric field induced charge injection or exhaustion in organic thin film transistor

The conductivity of organic semiconductors is measured {\it in-situ} and continuously with a bottom contact configuration, as a function of film thickness at various gate voltages. The depletion layer thickness can be directly determined as a shift of the threshold thickness at which electric current began to flow. The {\it in-situ} and continuous measurement can also determine qualitatively the accumulation layer thickness together with the distribution function of injected carriers. The accumulation layer thickness is a few mono layers, and it does not depend on gate voltages, rather depends on the chemical species.Comment: 4 figures, to be published in Phys. Rev.

Conserved features of non-primate bilaminar disc embryos and the germline.

Post-implantation embryo development commences with a bilaminar disc in most mammals, including humans. Whereas access to early human embryos is limited and subject to greater ethical scrutiny, studies on non-primate embryos developing as bilaminar discs offer exceptional opportunities for advances in gastrulation, the germline, and the basis for evolutionary divergence applicable to human development. Here, we discuss the advantages of investigations in the pig embryo as an exemplar of development of a bilaminar disc embryo with relevance to early human development. Besides, the pig has the potential for the creation of humanized organs for xenotransplantation. Precise genetic engineering approaches, imaging, and single-cell analysis are cost effective and efficient, enabling research into some outstanding questions on human development and for developing authentic models of early human development with stem cells

Particle Monte Carlo simulation of string-like colloidal assembly in 2 dimensions

We simulate structural phase behavior of polymer-grafted colloidal particles by molecular Monte Carlo technique. Interparticle potential, which has a finite repulsive square-step outside a rigid core of the colloid, was previously confirmed via numerical self-consistent field calculation. This model potential is purely repulsive. We simulate these model colloids in the canonical ensemble in 2 dimensions and find that these particles containing no interparticle attraction self-assemble and align in a string-like assembly, at low temperature and high density. This string-like colloidal assembly is related to percolation phenomena. Analyzing the cluster size distribution and the average string length, we build phase diagrams and discover that the average string length diverges around the region where the melting transition line and the percolation transition line cross. This result is similar to Ising spin systems, in which the percolation transition line and the order-disorder line meet at a critical point.Comment: 11 pages, 14 figure

Lentivector Transduction Improves Outcomes Over Transplantation of Human HSCs Alone in NOD/SCID/Fabry Mice

Fabry disease is a lysosomal storage disorder caused by a deficiency of a-galactosidase A (a-gal A) activity that results in progressive globotriaosylceramide (Gb(3)) deposition. We created a fully congenic nonobese diabetic (NOD)/severe combined immunodeficiency (SCID)/Fabry murine line to facilitate the in vivo assessment of human cell-directed therapies for Fabry disease. This pure line was generated after 11 generations of backcrosses and was found, as expected, to have a reduced immune compartment and background a-gal A activity. Next, we transplanted normal human CD34(+) cells transduced with a control (lentiviral vector-enhanced green fluorescent protein (LV-eGFP)) or a therapeutic bicistronic LV (LV-a-gal A/internal ribosome entry site (IRES)/hCD25). While both experimental groups showed similar engraftment levels, only the therapeutic group displayed a significant increase in plasma a-gal A activity. Gb(3) quantification at 12 weeks revealed metabolic correction in the spleen, lung, and liver for both groups. Importantly, only in the therapeutically-transduced cohort was a significant Gb(3) reduction found in the heart and kidney, key target organs for the amelioration of Fabry disease in humans.Fil: Pacienza, Natalia Alejandra. University Health Network; Canadá. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Yoshimitsu, Makoto. Kagoshima University; Japón. University Health Network; CanadáFil: Mizue, Nobuo. University Health Network; CanadáFil: Au, Bryan C. Y.. University Health Network; CanadáFil: Wang, James C. M.. University Health Network; CanadáFil: Fan, Xin. University Health Network; CanadáFil: Takenaka, Toshihiro. Kagoshima University; JapónFil: Medin, Jeffrey A. University Health Network; Canadá. University of Toronto; Canad