Ferromagnetic Resonance in Spinor Dipolar Bose--Einstein Condensates

We used the Gross--Pitaevskii equations to investigate ferromagnetic resonance in spin-1 Bose--Einstein condensates with a magnetic dipole-dipole interaction. By introducing the dipole interaction, we obtained equations similar to the Kittel equations used to represent ferromagnetic resonance in condensed matter physics. These equations indicated that the ferromagnetic resonance originated from dipolar interaction, and that the resonance frequency depended upon the shape of the condensate. Furthermore, spin currents driven by spin diffusions are characteristic of this system.Comment: 8 pages, 10 figure

Spin echo in spinor dipolar Bose-Einstein condensates

We theoretically propose and numerically realize spin echo in a spinor Bose--Einstein condensate (BEC). We investigate the influence on the spin echo of phase separation of the condensate. The equation of motion of the spin density exhibits two relaxation times. We use two methods to separate the relaxation times and hence demonstrate a technique to reveal magnetic dipole--dipole interactions in spinor BECs.Comment: 4 pages, 5 figure

Dynamics of weakly localized waves

We develop a transport theory to describe the dynamics of (weakly) localized waves in a quasi-1D tube geometry both in reflection and in transmission. We compare our results to recent experiments with microwaves, and to other theories such as random matrix theory and supersymmetric theory.Comment: RevTeX, 4 pages, 2 figure

Time-Lapse Video Microscopy Analysis Reveals Astral Microtubule Detachment in the Yeast Spindle Pole Mutant cnm67

Saccharomyces cerevisiae cnm67Δ cells lack the spindle pole body (SPB) outer plaque, the main attachment site for astral (cytoplasmic) microtubules, leading to frequent nuclear segregation failure. We monitored dynamics of green fluorescent protein–labeled nuclei and microtubules over several cell cycles. Early nuclear migration steps such as nuclear positioning and spindle orientation were slightly affected, but late phases such as rapid oscillations and insertion of the anaphase nucleus into the bud neck were mostly absent. Analyzes of microtubule dynamics revealed normal behavior of the nuclear spindle but frequent detachment of astral microtubules after SPB separation. Concomitantly, Spc72 protein, the cytoplasmic anchor for the γ-tubulin complex, was partially lost from the SPB region with dynamics similar to those observed for microtubules. We postulate that in cnm67Δ cells Spc72–γ-tubulin complex-capped astral microtubules are released from the half-bridge upon SPB separation but fail to be anchored to the cytoplasmic side of the SPB because of the absence of an outer plaque. However, successful nuclear segregation in cnm67Δ cells can still be achieved by elongation forces of spindles that were correctly oriented before astral microtubule detachment by action of Kip3/Kar3 motors. Interestingly, the first nuclear segregation in newborn diploid cells never fails, even though astral microtubule detachment occurs