Modelling of vorticity, sound and their interaction in two-dimensional superfluids

Vorticity in two-dimensional superfluids is subject to intense research efforts due to its role in quantum turbulence, dissipation and the BKT phase transition. Interaction of sound and vortices is of broad importance in Bose-Einstein condensates and superfluid helium [1-4]. However, both the modelling of the vortex flow field and of its interaction with sound are complicated hydrodynamic problems, with analytic solutions only available in special cases. In this work, we develop methods to compute both the vortex and sound flow fields in an arbitrary two-dimensional domain. Further, we analyse the dispersive interaction of vortices with sound modes in a two-dimensional superfluid and develop a model that quantifies this interaction for any vortex distribution on any two-dimensional bounded domain, possibly non-simply connected, exploiting analogies with fluid dynamics of an ideal gas and electrostatics. As an example application we use this technique to propose an experiment that should be able to unambiguously detect single circulation quanta in a helium thin film.Comment: 23 pages, 8 figure

Integrasi Pembelajaran Kanji dengan Pembelajaran Sakubun untuk Meningkatkan Kemampuan Menulis

Research aims to find the influence of strategies used in intermediate kanji learning, i.e. in a more applicative class using kanji, on middle kanji and composition class (sakubun). Research viewed and compared the influence of students\u27 mark in Intermediate Kanji with their mark in Sakubun. The questionnaire used in this research was the Strategy Inventory for Language Learning (SILL) consisting of 50 questions associated with types of strategy to learn kanji. The result obtained using T-test and correlation test was the students\u27 mark in kanji affected their mark in Sakubun. The relationship is the higher mark in kanji, the higher mark in Sakubun. As a conclusion, student essay writing ability is affected by the numbers of kanji remembered and used by students

Cavity Optomechanical Magnetometer

A cavity optomechanical magnetometer is demonstrated where the magnetic field induced expansion of a magnetostrictive material is transduced onto the physical structure of a highly compliant optical microresonator. The resulting motion is read out optically with ultra-high sensitivity. Detecting the magnetostrictive deformation of Terfenol-D with a toroidal whispering gallery mode (TWGM) resonator a peak sensitivity of 400 nT/Hz^.5 was achieved with theoretical modelling predicting that sensitivities of up to 500 fT/Hz^.5 may be possible. This chip-based magnetometer combines high-sensitivity and large dynamic range with small size and room temperature operation