Local structure in nematic and isotropic liquid crystals

By computer simulations of systems of ellipsoids, we study the influence of the isotropic/nematic phase transition on the direct correlation functions (DCF) in anisotropic fluids. The DCF is determined from the pair distribution function by solving the full Ornstein-Zernike equation, without any approximations. Using a suitable molecular-fixed reference frame, we can distinguish between two qualitatively different contributions to the DCF: One which preserves rotational invariance, and one which breaks it and vanishes in the isotropic phase. We find that the symmetry preserving contribution is barely affected by the phase transition. However, symmetry breaking contributions emerge in the nematic phase and may become quite substantial. Thus the DCF in a nematic fluid is not rotationally invariant. In the isotropic fluid, the DCF is in good agreement with the prediction of the Percus-Yevick theory.Comment: to appear in J. Chem. Phy

Spectropolarimetry of the borderline Seyfert 1 galaxy ESO 323-G077

We report the detection of high linear polarization in the bright Seyfert 1 galaxy ESO 323-G077. Based on optical spectropolarimetry with FORS1 at the VLT we find a continuum polarization which ranges from 2.2 % at 8300A to 7.5 % at 3600A. Similar amounts of linear polarization are found for the broad emission lines, while the narrow lines are not polarized. The position angle of the polarization is independent of the wavelength and found to be perpendicular to the orientation of the extended [OIII] emission cone of this galaxy. Within the standard model of Seyfert nuclei the observations can be well understood assuming that this AGN is observed at an inclination angle where the nucleus is partially obscured and seen mainly indirectly in the light scattered by dust clouds within or above the torus and the illuminated inner edge of the dust torus itself. Hence we conclude that ESO 323-G077 is a borderline Seyfert 1 galaxy which can provide important information on the geometric properties of active nuclei

Steering the potential barriers: entropic to energetic

We propose a new mechanism to alter the nature of the potential barriers when a biased Brownian particle under goes a constrained motion in narrow, periodic channel. By changing the angle of the external bias, the nature of the potential barriers changes from purely entropic to energetic which in turn effects the diffusion process in the system. At an optimum angle of the bias, the nonlinear mobility exhibits a striking bell-shaped behavior. Moreover, the enhancement of the scaled effective diffusion coefficient can be efficiently controlled by the angle of the bias. This mechanism enables the proper design of channel structures for transport of molecules and small particles. The approximative analytical predictions have been verified by precise Brownian dynamic simulations.Comment: (6 pages, 7 figures) Submitted to PR

Implications of financial sector consolidation

Bank mergers ; Consolidation and merger of corporations

Online taxation

Internet ; Taxation

The Dirac propagator in the extreme Kerr metric

Starting with the Dirac equation in the extreme Kerr metric we derive an integral representation for the propagator of solutions of the Cauchy problem with initial data in the class of smooth compactly supported functions.Comment: 9 pages, one more reference adde

Fluctuation effects in ternary AB+A+B polymeric emulsions

We present a Monte Carlo approach to incorporating the effect of thermal fluctuations in field theories of polymeric fluids. This method is applied to a field-theoretic model of a ternary blend of AB diblock copolymers with A and B homopolymers. We find a shift in the line of order-disorder transitions from their mean-field values, as well as strong signatures of the existence of a bicontinuous microemulsion phase in the vicinity of the mean-field Lifshitz critical point. This is in qualitative agreement with a recent series of experiments conducted with various three-dimensional realizations of this model system. Further, we also compare our results and the performance of the presently proposed simulation method to that of an alternative method involving the integration of complex Langevin dynamical equations.Comment: minor changes, references adde