Novel approaches facilitating neuraxial anesthesia placement in pregnant women with morbid obesity: case descriptions.

Clinical management of pregnant women with morbid obesity poses challenges in performing neuraxial anesthesia as well as positioning for cesarean delivery. Occupational injuries are also known to occur while caring for patients with morbid obesity. We describe two novel approaches to assist neuraxial anesthesia administration and positioning for cesarean delivery. With the assistance of the Institution's Safe Patient Handling and Mobility Team, a universal high-back sling can be placed to lift the patient into a sitting position before neuraxial anesthesia procedure. After placement of combined spinal epidural anesthesia, the ceiling lift is used to lift the patient into a seated position and then rotate to the appropriate location on the operating room table to facilitate supine positioning. The lifting system reduces shearing of the patient's posterior and compromising the epidural site. Team members also report reduced effort required when positioning patients from seated to supine on the operating room table. The second approach is the application of TraxiTM abdominal pannus retractor to retract fat folds encroaching on the epidural placement site in pregnant women with morbid obesity. This is particularly useful when the traditional taping of fat folds away from the site is inadequate. The pannus retractor results in a flatter surface facilitating epidural placement. We have introduced these two approaches into our clinical practice for pregnant women with morbid obesity requiring cesarean delivery under neuraxial anesthesia.

Towards efficient and broadband four-wave-mixing using short-length dispersion tailored lead silicate holey fibers.

We demonstrate four-wave-mixing based wavelength conversion at 1.55 mum in a 2.2 m-long dispersion-shifted lead-silicate holey fiber. For a pump peak power of ~6 W, a conversion efficiency of -6 dB is achieved over a 3-dB bandwidth of ~30 nm. Numerical simulations are used to predict the performance of the fiber for different experimental conditions and to address the potential of dispersion-tailored lead silicate holey fibers in wavelength conversion applications utilizing four-wave-mixing. It is shown that highly efficient and broadband wavelength conversion, covering the entire C-band, can be achieved for such fibers at reasonable optical pump powers and for fiber lengths as short as ~2 m.

Bismuth glass holey fibers with high nonlinearity.

We report on the progress of bismuth oxide glass holey fibers for nonlinear device applications. The use of micron-scale core diameters has resulted in a very high nonlinearity of 1100 W-1 km-1 at 1550 nm. The nonlinear performance of the fibers is evaluated in terms of a newly introduced figure-of-merit for nonlinear device applications. Anomalous dispersion at 1550 nm has been predicted and experimentally confirmed by soliton self-frequency shifting. In addition, we demonstrate the fusion-splicing of a bismuth holey fiber to silica fibers, which has resulted in reduced coupling loss and robust single mode guiding at 1550 nm.

Highly nonlinear and anomalously dispersive lead silicate glass holey fibers.

In this paper we present significant progress on the fabrication of small-core lead-silicate holey fibers. The glass used in this work is SF57, a commercially available, highly nonlinear Schott glass. We report the fabrication of small core SF57 fibers with a loss as low as 2.6 dB/m at 1550 nm, and the fabrication of fibers with a nonlinear coefficient as high as 640 W-1km-1. We demonstrate the generation of Raman solitons at ~1550 nm in a short length of such a fiber which highlights the fact that the group velocity dispersion can be anomalous at these wavelengths despite the large normal material dispersion of the glass around 1550nm.

Aeroelastic structural acoustic control.

Static, constant-gain, output-feedback control compensators were designed to increase the transmission loss across a panel subjected to mean flow on one surface and a stationary, acoustic half-space on the opposite surface. The multi-input, multi-output control system was based upon the use of an array of colocated transducer pairs. The performance of the static-gain, output-feedback controller was compared to that of the full state-feedback controller using the same control actuator arrays, and was found to yield comparable levels of performance for practical limitations on control effort. Additionally, the resulting static compensators proved to be dissipative in nature, and thus the design varied little as a function of the aeroelastic coupling induced by the fluid-structure interaction under subsonic flow conditions. Several parametric studies were performed, comparing the effects of control-effort penalty as well as the number of transducer pairs used in the control system.