Monte Carlo study of tunable negative-zero-positive index of refraction in nanosphere dispersed liquid crystals

Khoo et al.1, 2 have shown that nanosphere dispersed nematic liquid crystal (NDLC) constitutes a new type of metamaterial with index of refraction tunable from negative to positive values. Recently3 we have combined this approach with Monte Carlo simulations of inhomogeneous molecular order in planar NLC cells. Lebwohl - Lasher effective hamiltonian with Rapini - Papoular term for anchoring forces was used. Electric field and amplitude of anchoring forces are control parameters which determine the profiles of order parameter. In this paper we study, using the same approach, local spatial distribution of refractive index in NDLC planar cell. We show that NDLC material consists of layers with negative-zero-positive index of refraction. The spatial organization of those layers strongly depends on incident light wavelength. The role of spatially modulated external electric field for tuning of refractive index of NDLC is briefly discussed

Preface for OPTMAT Special Volume: WOREN 2010

The First Polish – French Workshop on Organic Electronics and Nanophotonics, WOREN 2010, was held in Swieradow Zdroj close to Wroclaw (Poland), from January 31 to February 04, 2010. The workshop was organized jointly by the Institute of Physical and Theoretical Chemistry and Institute of Physics, Wroclaw University of Technology

Second-harmonic generation in poled polymers: pre-poling history paradigm

Experimental studies of second harmonic generation (SHG) from electric-field poled PMMA - DR1 system show occurrence of a maximum in diagonal and off diagonal tensor components χ(2)(−2ω; ω, ω) at 15 mol % concentration and a rapid decrease above, with a stabilization. The origin of the observed concentration dependence is studied using the Monte Carlo (MC) modeling. We find that presence of maximum is conditioned by the pre-poling history of the sample, when entanglement of linear dipolar structures takes place. Length of the pre-poling interval is an important kinetic parameter which differentiates between various non-exponential kinetics of build-up of polar phase responsible for strong/weak SHG susceptibility

A Simple Model of Liquid-liquid Phase Transitions

In recent years, a second fluid-fluid phase transition has been reported in several materials at pressures far above the usual liquid-gas phase transition. In this paper, we introduce a new model of this behavior based on the Lennard-Jones interaction with a modification to mimic the different kinds of short-range orientational order in complex materials. We have done Monte Carlo studies of this model that clearly demonstrate the existence of a second first-order fluid-fluid phase transition between high- and low-density liquid phases

An Extraterritorial FDA: Could the Food and Drug Administration Apply Its Informed Consent Requirement Abroad Consistent with International Law?

This paper addresses the regulatory challenges wrought by the increasing amount of human subject drug testing conducted in developing countries in support of new drug applications to the Food and Drug Administration. Specifically, it examines the difficulty of enforcing the “informed consent” requirement for ethical scientific research performed in foreign territory. In poorer regions, a lack of government oversight, lower regulatory standards, and barriers to communication have too frequently resulted in allegations of human experimentation performed without its participants’ informed consent. In order to solve this problem, some commentators have suggested that the FDA could apply its human subject protections to foreign clinical research, and enforce them through injunctions or criminal prosecutions. However, the international legal limits on states’ prescriptive jurisdiction may prohibit this exercise of extraterritoriality. After analyzing the proposed extraterritorial regulation of foreign drug testing under the traditional bases and limitations of prescriptive jurisdiction, this paper concludes that such regulation would likely violate international law. However, because nonconsensual clinical research has previously been regarded as a crime against humanity, the FDA might be able to bring criminal prosecutions under the principal of “universal jurisdiction” against investigators or sponsors who conducted studies without their subjects’ informed consent. This analysis offers both positive and normative conclusions regarding the international legal system and the human rights regime