Spatiotemporal Model for Kerr Comb Generation in Whispering Gallery Mode Resonators

We establish an exact partial differential equation to model Kerr comb generation in whispering-gallery mode resonators. This equation is a variant of the Lugiato-Lefever equation that includes higher-order dispersion and nonlinearity. This spatio-temporal model, whose main variable is the total intracavity field, is significantly more suitable than the modal expansion approach for the theoretical understanding and the numerical simulation of wide-span combs. It allows us to explore pulse formation in which a large number of modes interact cooperatively. This versatile approach can be straightforwardly extended to include higher-order dispersion, as well as other phenomena like Raman, Brillouin and Rayleigh scattering. We demonstrate for the first time that when the dispersion is anomalous, Kerr comb generation can arise as the spectral signature of dissipative cavity solitons, leading to wide-span combs with low pumping.Comment: 5 pages, 2 figure

Bonding of reusable surface insulation with low density silicone foams

The development and evaluation of a reduced density, high reliable foamed bond strain isolation system for attaching reusable surface insulation to the space shuttle structure are reported. Included are data on virgin materials as well as on materials that received 100 cycles of exposure to 650 F for approximately 20 minutes per cycle. Room temperature vulcanizing silicon elastomers meet all the requirments for an adhesive bonding system

Fourier domain preconditioned conjugate gradient algorithm for atmospheric tomography

By 'atmospheric tomography' we mean the estimation of a layered atmospheric turbulence profile from measurements of the pupil-plane phase (or phase gradients) corresponding to several different guide star directions. We introduce what we believe to be a new Fourier domain preconditioned conjugate gradient (FD-PCG) algorithm for atmospheric tomography, and we compare its performance against an existing multigrid preconditioned conjugate gradient (MG-PCG) approach. Numerical results indicate that on conventional serial computers, FD-PCG is as accurate and robust as MG-PCG, but it is from one to two orders of magnitude faster for atmospheric tomography on 30 m class telescopes. Simulations are carried out for both natural guide stars and for a combination of finite-altitude laser guide stars and natural guide stars to resolve tip-tilt uncertainty

Wind enhanced planetary escape: Collisional modifications

The problem of thermal escape is considered in which both the effects of thermospheric winds at the exobase and collisions below the exobase are included in a Monte Carlo calculation. The collisions are included by means of a collisional relaxation layer of a background gas which models the transition region between the exosphere and the thermosphere. The wind effects are considered in the limiting cases of vertical and horizontal flows. Two species are considered: terrestrial hydrogen and terrestrial helium. In the cases of terrestrial hydrogen the escape fluxes were found to be strongly filtered or throttled by collisions at high exospheric temperatures. The model is applied to molecular hydrogen diffusing through a methane relaxation layer under conditions possible on Titan. The results are similar to the case of terrestrial hydrogen with wind enhanced escape being strongly suppressed by collisions. It is concluded that wind enhanced escape is not an important process on Titan

Results From the Long-Term Inmate Survey: Focus on Child Abuse Histories

This report of long-term inmates in Alaska correctional facilities attempts to describe the childhood experiences of a sample of long-term inmates, address the "cycle of abuse" issue; and present the correlates of abuse which may impact the pattern of offending or inmate functioning. Over 80 percent of long-term inmates report having been physically abused as children; over 65 percent report having suffered neglect.Alaska Department of CorrectionsResults from the Long Term Inmate Study: Focus on Child Abuse Histories / Incidence of Child Abuse and the Relationship to Criminality / Measuring Child Abuse and Neglect: A Review of Methods / Survey Methods and Administration / An Assessment of Survey Biases / Tables to Support Profile Analysis / Personal Interview Administration and Results / Correlates of Abus

Preliminary Results From the Long-Term Inmate Survey: Focus on Child Abuse Histories

This preliminary report of long-term inmates in Alaska correctional facilities finds that over 80 percent of long-term inmates report having been physically abused as children, over 65 percent report having suffered neglect. Other findings related to the child abuse histories of long-term inmates are also reported.Alaska Department of Correction