Condensed Matter Theory

Abstract:

The response of a short DNA segment to bending is studied, taking into account the anisotropy in the bending rigidities. It is shown that due to the helical structure of DNA, the anisotropy in the bending rigidities can lead to the formation of kinks and modulations in the curvature, depending on the values of the elastic constants. The typical wavelength for the modulations, or the distance between the neighbouring kinks, is found to be set by half of the DNA pitch. © 2005 IOP Publishing Ltd.

Abstract:

The microscopic mechanism for thermodiffusion or the Ludwig-Soret effect is investigated for a single charged colloidal particle. For the specific example of a charged permeable membrane, the different forces arising from the interplay between electrostatic interaction and entropy are identified and their magnitudes are calculated in both no-salt and salt-saturated limits. The competition between these forces, which is controlled by the salt density, is shown to decide the direction of motion for the colloids. © 2005 IOP Publishing Ltd.

Abstract:

The appearance of a luminescence ring around a central illumination spot in quantum well structures is now well understood in terms of charge separation between the electron and hole gasses in the quantum well region with the ring appearing at their boundary. We propose a slightly modified model including Coulomb interaction between the electron and hole gas and their image charge. © 2005 Elsevier Ltd. All rights reserved.