Safe Positively Invariant Sets for Spacecraft Obstacle Avoidance

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140643/1/1.g000115.pd

An optical coherence microscope for 3-dimensional imaging in developmental biology

An optical coherence microscope (OCM) has been designed and constructed to acquire 3-dimensional images of highly scattering biological tissue. Volume-rendering software is used to enhance 3-D visualization of the data sets. Lateral resolution of the OCM is 5 mm (FWHM), and the depth resolution is 10 mm (FWHM) in tissue. The design trade-offs for a 3-D OCM are discussed, and the fundamental photon noise limitation is measured and compared with theory. A rotating 3-D image of a frog embryo is presented to illustrate the capabilities of the instrument

Outcomes of 23-gauge pars plana vitrectomy in combined scleral buckling and vitrectomy for complex rhegmatogenous retinal detachments

Rhegmatogenous retinal detachments associated with proliferative vitreoretinopathy, giant retinal tears, ocular trauma, proliferative diabetic retinopathy, or necrotizing retinitis are considered more complex than those without these factors. The aim of the current review is to address the surgical outcomes and complications of 23-gauge pars plana vitrectomy with scleral buckling (23GPPV/SB) for repair of these complex retinal detachments. This retrospective study involved 54 eyes of 53 patients who underwent 23GPPV/SB between July 2007 and September 2009. Preoperative diagnosis, surgical technique, preoperative and postoperative visual acuities, intraoperative and postoperative complications, and anatomic reattachment rates were examined. Fifty-four eyes of 53 patients were reviewed in this study and indications for surgery varied. Mean logarithm of the minimal angle of resolution (logMAR) pre- and post-operative visual acuities were 1.166 (20/293) and 0.780 (20/120), respectively, which led to a statistically significant improvement in logMAR (P=0.0165). Single operation and final reattachment rates were 87% (47 of 54 eyes) and 100%, respectively. Postoperative complications included choroidal effusion/hemorrhage (14.8%, 8 of 54 eyes) and vitreous hemorrhage (11.1%, 6 of 54 eyes). Other more infrequent complications included hyphema (9.3%, 5 of 54 eyes), hypotony (5.6%, 3 of 54 eyes) and ocular hypertension > 35 mmHg (3.7%, 2 of 54 eyes). A total of 31.5% (17 of 54 eyes) of patients had a complication in the postoperative time period, but 58.8% of these resolved spontaneously without requiring an intervention. 23GPPV/SB may be considered for complex retinal detachment repair with good anatomic reattachment rates, but with relatively high complication rates

West Nile Virus Economic Impact, Louisiana, 2002

2002 WNV epidemic in Louisiana incurred substantial short-term economic cost

Improving the Representation of Snow Crystal Properties within a Single-Moment Microphysics Scheme

The assumptions of a single-moment microphysics scheme (NASA Goddard) were evaluated using a variety of surface, aircraft and radar data sets. Fixed distribution intercepts and snow bulk densities fail to represent the vertical variability and diversity of crystal populations for this event. Temperature-based equations have merit, but they can be adversely affected by complex temperature profiles that are inverted or isothermal. Column-based approaches can mitigate complex profiles of temperature but are restricted by the ability of the model to represent cloud depth. Spheres are insufficient for use in CloudSat reflectivity comparisons due to Mie resonance, but reasonable for Rayleigh scattering applications. Microphysics schemes will benefit from a greater range of snow crystal characteristics to accommodate naturally occurring diversity

The NASA Decadal Survey Observing-System Study for Aerosols and Clouds,Convection, and Precipitation (ACCP)

No abstract availabl

Motion-Sensitive 3-D Optical Coherence Microscope Operating at 1300 nm for the Visualization of Early Frog Development

We present 3-dimensional volume-rendered in vivo images of developing embryos of the African clawed frog Xenopus laevis taken with our new en-face-scanning, focus-tracking OCM system at 1300 nm wavelength. Compared to our older instrument which operates at 850 nm, we measure a decrease in the attenuation coefficient by 33%, leading to a substantial improvement in depth penetration. Both instruments have motion-sensitivity capability. By evaluating the fast Fourier transform of the fringe signal, we can produce simultaneously images displaying the fringe amplitude of the backscattered light and images showing the random Brownian motion of the scatterers. We present time-lapse movies of frog gastrulation, an early event during vertebrate embryonic development in which cell movements result in the formation of three distinct layers that later give rise to the major organ systems. We show that the motion-sensitive images reveal features of the different tissue types that are not discernible in the fringe amplitude images. In particular, we observe strong diffusive motion in the vegetal (bottom) part of the frog embryo which we attribute to the Brownian motion of the yolk platelets in the endoderm