View-Invariant Regions and Mobile Robot Self-Localization

This paper addresses the problem of mobile robot self-localization given a polygonal map and a set of observed edge segments. The standard approach to this problem uses interpretation tree search with pruning heuristics to match observed edges to map edges. Our approach introduces a preprocessing step in which the map is decomposed into 'view-invariant regions' (VIRs). The VIR decomposition captures information about map edge visibility, and can be used for a variety of robot navigation tasks. Basing self-localization search on VIRs greatly reduces the branching factor of the search tree and thereby simplifies the search task. In this paper we define the VIR decomposition and give algorithms for its computation and for self-localization search. We present results of simulations comparing standard and VIR-based search, and discuss the application of the VIR decomposition to other problems in robot navigation

10Gbit/s modulation of a fast switching slotted Fabry-Pérot tunable laser

The device used is a three-section, 3mum wide ridge waveguide laser based on commercially available material. During the fabrication a series of slots are introduced into the front and back sections, which act as sites of internal reflections. The slots are etched to a depth that just penetrates the top of the upper waveguide resulting in an internal reflectance of-1% at each slot. The front, middle, and back sections are 180, 690 and 170 microns long respectively. In this work the back and middle sections are tied together electrically allowing simpler control of the device. By varying the applied DC currents, eight discrete channels are observed over a range of approximately 19nm

Five-day regimen of intramuscular or subcutaneous self-administered adrenocorticotropic hormone gel for acute exacerbations of multiple sclerosis: a prospective, randomized, open-label pilot trial

James P Simsarian, Carol Saunders, D Michelle SmithNeurology Center of Fairfax Ltd, Fairfax, VA, USABackground: Despite over 50 years of experience with adrenocorticotropic hormone (ACTH) as a treatment for acute exacerbations of multiple sclerosis, there have been no trials examining the options of the 2–3-week dosing regimen or intramuscular injection protocol used in the original trials. At our clinic, we performed a small, prospective, randomized pilot study to examine the efficacy and safety of, and patient satisfaction with, a short (five-day) self-administered ACTH dosing protocol for exacerbations of multiple sclerosis, and to compare the subcutaneous and intramuscular routes of administration.Methods: Patients for this study were recruited from an outpatient treatment clinic. Each patient self-administered natural ACTH gel 80 U/day by subcutaneous or intramuscular injection for five consecutive days and was evaluated at baseline and on days 7 and 14. Patient feedback was collected using the Patient Global Impression of Change (PGI-C, the primary efficacy measure), a patient global visual analog scale, the Expanded Disability Status Scale, a timed walk, the Nine-hole Peg Test, and the Clinical Global Impression of Change.Results: Of the 20 enrolled patients (mean age 39.5 years), 19 completed the study. On day 14, 61.1% of patients (11 of 18 with day 14 scores) were treatment responders, and rated their condition as "very much improved" or "much improved" on the PGI-C. The intramuscular group had numerically more responders, but there was no significant difference in the proportion of responders between the intramuscular and subcutaneous groups at day 14 (P = 0.3). The intramuscular route of injection was associated with more injection site pain than the subcutaneous route.Conclusion: A shorter five-day course of intramuscular or subcutaneous ACTH gel may improve symptoms associated with acute exacerbations of multiple sclerosis. Larger studies with standard of care controls are needed to confirm whether this shorter course of intramuscular or subcutaneous ACTH gel is effective and could potentially be substituted for the standard 14-day treatment.Keywords: adrenocorticotropic hormone, ACTH, multiple sclerosis, acute exacerbations, Acthar® Gel, autoimmune disease

Morton Electronics: The Collapse Of High-Performance, Self-Managed Work Teams

It was clear that top management was seriously pondering the long-term viability of Robert Mitchell’s manufacturing group…at least as it was currently structured.  Robert sat at his desk wondering what he could do to keep his job as manager and maintain control of the group. He concluded that he needed to do more than develop some kind of cost savings plan.  He needed to think outside the box and come up with something more spectacular to impress top management.  He would take the lemons and make lemonade

Calculations of parity nonconserving s-d transitions in Cs, Fr, Ba II, and Ra II

We have performed ab initio mixed-states and sum-over-states calculations of parity nonconserving (PNC) electric dipole (E1) transition amplitudes between s-d electron states of Cs, Fr, Ba II, and Ra II. For the lower states of these atoms we have also calculated energies, E1 transition amplitudes, and lifetimes. We have shown that PNC E1 transition amplitudes between s-d states can be calculated to high accuracy. Contrary to the Cs 6s-7s transition, in these transitions there are no strong cancelations between different terms in the sum-over-states approach. In fact, there is one dominating term which deviates from the sum by less than 20%. This term corresponds to an s-p_{1/2} weak matrix element, which can be calculated to better than 1%, and a p_{1/2}-d_{3/2} E1 transition amplitude, which can be measured. Also, the s-d amplitudes are about four times larger than the corresponding s-s transitions. We have shown that by using a hybrid mixed-states/sum-over-states approach the accuracy of the calculations of PNC s-d amplitudes could compete with that of Cs 6s-7s if p_{1/2}-d_{3/2} E1 amplitudes are measured to high accuracy.Comment: 15 pages, 8 figures, submitted to Phys. Rev.

Imaging the phase of an evolving Bose-Einstein condensate wavefunction

We demonstrate a spatially resolved autocorrelation measurement with a Bose-Einstein condensate (BEC) and measure the evolution of the spatial profile of its quantum mechanical phase. Upon release of the BEC from the magnetic trap, its phase develops a form that we measure to be quadratic in the spatial coordinate. Our experiments also reveal the effects of the repulsive interaction between two overlapping BEC wavepackets and we measure the small momentum they impart to each other

Spectrum of light scattering from an extended atomic wave packet

The spectrum of the light scattered from an extended atomic wave packet is calculated. For a wave packet consisting of two spatially separated peaks moving on parallel trajectories, the spectrum contains Ramsey-like fringes that are sensitive to the phase difference between the two components of the wave packet. Using this technique, one can establish the mutual coherence of the two components of the wave packet without recombining them.Comment: 4 page

Spatial interference of coherent atomic waves by manipulation of the internal quantum state

A trapped 87Rb Bose-Einstein condensate is initially put into a superposition of two internal states. Under the effect of gravity and by means of a second transition, we prepare two vertically displaced condensates in the same internal state. These constitute two coherent sources of matter waves with adjustable spatial separation. Fringe patterns, observed after free expansion, are associated with the interplay between internal and external degrees of freedom and substantially agree with those for a double slit experiment

Dynamics of rotating Bose-Einstein condensates probed by Bragg scattering

Gaseous Bose-Einstein condensates (BECs) have become an important test bed for studying the dynamics of quantized vortices. In this work we use two-photon Doppler sensitive Bragg scattering to study the rotation of sodium BECs. We analyze the microscopic flow field and present laboratory measurements of the coarse-grained velocity profile. Unlike time-of-flight imaging, Bragg scattering is sensitive to the direction of rotation and therefore to the phase of the condensate. In addition, we have non-destructively probed the vortex flow field using a sequence of two Bragg pulses.Comment: 13 pages, 5 figures. Invited paper submitted to a special issue on "Nonlinear Waves" of the (Elsevier) journal 'Math. Comput. Simul.', for participants in the 4th IMACS International Conference on Nonlinear Evolution Equations and Wave Phenomena (2005). Visit our website at http://www.physics.gatech.edu/chandra for additional informatio