Quantum slow motion

We simulate the center of mass motion of cold atoms in a standing, amplitude modulated, laser field as an example of a system that has a classical mixed phase-space. We show a simple model to explain the momentum distribution of the atoms taken after any distinct number of modulation cycles. The peaks corresponding to a classical resonance move towards smaller velocities in comparison to the velocities of the classical resonances. We explain this by showing that, for a wave packet on the classical resonances, we can replace the complicated dynamics in the quantum Liouville equation in phase-space by the classical dynamics in a modified potential. Therefore we can describe the quantum mechanical motion of a wave packet on a classical resonance by a purely classical motion

Supersymmetry in Slow Motion

We construct new theories of electroweak symmetry breaking that employ a combination of supersymmetry and discrete symmetries to stabilize the weak scale up to and beyond the energies probed by the LHC. These models exhibit conventional supersymmetric spectra but the fermion-sfermion-gaugino vertices are absent. This closes many conventional decay channels, thereby allowing several superpartners to be stable on collider time scales. This opens the door to the possibility of directly observing R-hadrons and three flavors of sleptons inside the LHC detectors.Comment: A reference added. The discussion on the Higgs sector expanded. The version accepted for publication in JHE

Effectiveness of slow motion video compared to real time video in improving the accuracy and consistency of subjective gait analysis in dogs

Objective measures of canine gait quality via force plates, pressure mats or kinematic analysis are considered superior to subjective gait assessment (SGA). Despite research demonstrating that SGA does not accurately detect subtle lameness, it remains the most commonly performed diagnostic test for detecting lameness in dogs. This is largely because the financial, temporal and spatial requirements for existing objective gait analysis equipment makes this technology impractical for use in general practice. The utility of slow motion video as a potential tool to augment SGA is currently untested. To evaluate a more accessible way to overcome the limitations of SGA, a slow motion video study was undertaken. Three experienced veterinarians reviewed video footage of 30 dogs, 15 with a diagnosis of primary limb lameness based on history and physical examination, and 15 with no indication of limb lameness based on history and physical examination. Four different videos were made for each dog, demonstrating each dog walking and trotting in real time, and then again walking and trotting in 50% slow motion. For each video, the veterinary raters assessed both the degree of lameness, and which limb(s) they felt represented the source of the lameness. Spearman’s rho, Cramer’s V, and t-tests were performed to determine if slow motion video increased either the accuracy or consistency of raters’ SGA relative to real time video. Raters demonstrated no significant increase in consistency or accuracy in their SGA of slow motion video relative to real time video. Based on these findings, slow motion video does not increase the consistency or accuracy of SGA values. Further research is required to determine if slow motion video will benefit SGA in other ways

Slow Motion

Student Number : 0310050V - MA research report - School of Literature and Language Studies - Faculty of HumanitiesThe rationale of this work is a peripatetic exploration, both literally and intellectually: the form echoes the content. The creative work stands on its own, but the theoretical reflection contributes retrospectively to the work as part of this peripatetic process. The theoretical reflection picks up the theme, though more formally, in order to create one coherent project. I have aimed to create a dialogue between the theory and creative work on a road that goes both ways. If it appears that the section of theory devoted to the poets is disproportionately long compared to the rest of the work, this is because I discovered in the course of my exploration that poets seem more predisposed to wandering than others

Quantum slow motion

We investigate the center-of-mass motion of cold atoms in a standing amplitude modulated laser field. We use a simple model to explain the momentum distribution of the atoms after any distinct number of modulation cycles. The atoms starting near a classical phase-space resonance move slower than we would expect classically. We explain this by showing that for a wave packet on the classical resonances we can replace the complicated dynamics in the quantum Liouville equation in phase space by its classical dynamics with a modified potential

Slow Motion of Charges Interacting Through the Maxwell Field

We study the Abraham model for $N$ charges interacting with the Maxwell field. On the scale of the charge diameter, $R_{\phi}$, the charges are a distance \eps^{-1}R_{\phi} apart and have a velocity \sqrt{\eps} c with \eps a small dimensionless parameter. We follow the motion of the charges over times of the order \eps^{-3/2}R_{\phi}/c and prove that on this time scale their motion is well approximated by the Darwin Lagrangian. The mass is renormalized. The interaction is dominated by the instantaneous Coulomb forces, which are of the order \eps^{2}. The magnetic fields and first order retardation generate the Darwin correction of the order \eps^{3}. Radiation damping would be of the order \eps^{7/2}