Behaviour of a shear-wave at a solid-smectic interface

Results of theoretical investigations into the behaviour of a shear wave at the boundary between an isotropic solid and a smectic A liquid crystal are presented. These results track the subsequent response of the smectic to the refracted wave. Using the techniques of Landau and Lifshitz for sound in isotropic fluids [1], we extend the results for smectic C by Gill and Leslie [2] and perform the analogous calculations for a sample of smectic A using the dynamic theory of Stewart [3]. These calculations enable a comparison between the results for smectic A and an extension, by the present authors, to the known results for smectic C. Motivated by the work of Auernhammer, Brand, and Pleiner [4, 5], mechanisms for determining the impact of perturbations upon the modes of response behaviour will be analysed, with plots demonstrating the amplitudes of these waves relative to that of the incident wave displayed for a range of typical physical parameters characteristic to smectic C and smectic A

Search for Spin-Dependent Short-Range Force Using Optically Polarized 3^3He Gas

We propose a new method to detect short-range \textit{P-} and \textit{T-} violating interactions between nucleons, based on measuring the precession frequency shift of polarized $^3$He nuclei in the presence of an unpolarized mass. To maximize the sensitivity, a high-pressure $^3$He cell with thin glass windows (250 $\rm\mu m$) is used to minimize the distance between the mass and $^3$He. The magnetic field fluctuation is suppressed by using the $^3$He gas in a different region of the cell as a magnetometer. Systematic uncertainties from the magnetic properties of the mass are suppressed by flipping both the magnetic field and spin directions. Without any magnetic shielding, our result has already reached the sensitivity of the current best limit. With improvement in uniformity and stability of the field, we can further improve the sensitivity by two orders of magnitude over the force range from $10^{-4}-10^{-2}$ m

Getting the story from child witnesses : exploring the application of a story grammar framework

Investigative interviews with children about alleged abuse were analysed to determine the degree to which the child\u27s responses adhered to a story grammar framework, and whether the presence of story grammar elements was associated with interviewers\u27 adherence to best-practice (i.e. open-ended) questioning. The sample included 51 interviews with child witnesses from across Australia. The interviews were administered by a police officer with children (37 girls and 14 boys) aged 3-16 years (M age = 103.82 months, SD = 34.21 months). The interviewers\u27 questions were categorised as open-ended or specific and the children\u27s responses were classified as a story grammar element, context/background information, or \u27don\u27t know\u27 responses. The majority of interviewer questions were specific in nature and the majority of children\u27s responses were context/background details. Open-ended questions were more successful in eliciting story grammar from children. Of the story grammar elements, the interviewers\u27 specific questions usually targeted setting and attempt details. These findings suggest that improvement in the narrative coherence of children\u27s reports of abusive events can potentially be achieved by increasing interviewers\u27 use of open-ended questions.<br /

Barrier Lowering and Field Penetration at Metal-Dielectric Interfaces

We report here photoemission measurements on Si-SiO_2-Al structures in which the metal-SiO_2 barrier energy has been determined as a function of the electric field strength E in the dielectric. The expected barrier lowering is the sum of two terms: a) the Schottky term, proportional to E^(1/2) and b) a term due to the penetration of the electric field into the metal electrode, proportional to E. The experimental results are in good agreement with the model, where the Schottky effect involves the optical value of the dielectric constant of the oxide and the Thomas-Fermi screening distance in the metal is 1 Å. To our knowledge this represents the first unambiguous quantitative determination of either effect in a polar dielectric, although the Schottky effect alone has been observed in silicon