Decadal-Scale Forecasting of Climate Drivers for Marine Applications.

Climate influences marine ecosystems on a range of time scales, from weather-scale (days) through to climate-scale (hundreds of years). Understanding of interannual to decadal climate variability and impacts on marine industries has received less attention. Predictability up to 10 years ahead may come from large-scale climate modes in the ocean that can persist over these time scales. In Australia the key drivers of climate variability affecting the marine environment are the Southern Annular Mode, the Indian Ocean Dipole, the El Niño/Southern Oscillation, and the Interdecadal Pacific Oscillation, each has phases that are associated with different ocean circulation patterns and regional environmental variables. The roles of these drivers are illustrated with three case studies of extreme events-a marine heatwave in Western Australia, a coral bleaching of the Great Barrier Reef, and flooding in Queensland. Statistical and dynamical approaches are described to generate forecasts of climate drivers that can subsequently be translated to useful information for marine end users making decisions at these time scales. Considerable investment is still needed to support decadal forecasting including improvement of ocean-atmosphere models, enhancement of observing systems on all scales to support initiation of forecasting models, collection of important biological data, and integration of forecasts into decision support tools. Collaboration between forecast developers and marine resource sectors-fisheries, aquaculture, tourism, biodiversity management, infrastructure-is needed to support forecast-based tactical and strategic decisions that reduce environmental risk over annual to decadal time scales.

Consideration of non-Poisson distributions for lidar applications.

Poisson statistics are traditionally used to estimate the mean and standard deviation of the mean in time-range realizations of received photon counts from stationary processes in incoherent-detection lidar systems. However, this approach must be modified if the process under study is measurably nonstationary to account for any additional (and potentially unanticipated) variability. We demonstrate that the modified approach produces a different form for the estimated standard deviation of the mean for lidar return counts, which can also be applied to binning of higher-order data products. This modified technique also serves to determine optimum time-range integrations, diagnose system stability, and constrain operational modes.

Roe v Wade and American fertility.

OBJECTIVES: This article examines the effect of abortion legalization on fertility rates in the United States. METHODS: Fertility rates were compared over time between states that varied in the timing of abortion legalization. RESULTS: States legalizing abortion experienced a 4% decline in fertility relative to states where the legal status of abortion was unchanged. The relative reductions in births to teens, women more than 35 years of age, non-White women, and unmarried women were considerably larger. If women did not travel between states to obtain an abortion, the estimated impact of abortion legalization on birth rates would be about 11%. CONCLUSIONS: A complete recriminalization of abortion nationwide could result in 440,000 additional births per year. A reversal of the Roe v Wade decision leaving abortion legal in some states would substantially limit this impact because of the extent of travel between states.

Long-term results of cemented total hip arthroplasty in patients 45 years old or younger. A 16-year follow-up study.

Forty-nine cemented total hip arthroplasties in patients younger than 45 years were reviewed, with an average follow-up period of 16.2 years. The results were compared with the same group previously reported at average follow-up periods of 4.5 and 9.2 years. Clinically satisfactory results were 27% at 16.2 years compared with 78% at 4.5 years and 58% at 9.2 years. The revision rate increased from 12% at 4.5 years to 33% at 9.2 years to 67% in this study. The revision rate for patients younger than 30 at the time of the index arthroplasty was 82% compared with 56% for those over 30. Impending failure was present in 81% of the 16 unrevised hips compared with 56% at 9.2 years and 29% at 4.5 years. Patients younger than 30, in Charnley category A or B, and with a diagnosis of osteonecrosis or osteoarthritis had the poorest clinical results. As in the previous two studies, the best results were obtained in category C patients who were over 30 years of age with inflammatory collagen disease. The purpose of this study is to report the long-term (average, 16.2 years) follow-up results of patients under the age of 45 who underwent cemented total hip arthroplasty at Rancho Los Amigos Medical Center between 1972 and 1978. The 4.5-year and 9.2-year results form the basis for comparison.

Lidar observations of the meteoric deposition of mesospheric metals.

The mesospheric sodium and iron layers at an altitude between about 80 and 110 kilometers are routinely monitored by atmospheric physicists using resonance fluorescence lidar techniques because these constituents are excellent tracers of mesopause chemistry and dynamics. The mesospheric metals are the products of meteoric ablation. Existing ablation profiles are model calculations based in part on radar observations of the ionized background atmosphere left in the wake of high-speed (> 20 kilometers per second) meteoroids. Thin trails of neutral metal atoms, ablated from individual meteoroids, are occasionally observed with high-power lidars. The vertical distribution of 101 sodium and 5 iron meteor trails observed during the past 4 years at Urbana, Illinois; Arecibo, Puerto Rico; and near Hawaii is approximately Gaussian in shape with a centroid height of 89.0 (+/- 0.3) kilometers and a root-mean-square width of 3.3 (+/- 0.2) kilometers. This directly measured ablation profile is nearly the same as the mean iron layer profile but is considerably different from existing models and the distribution of ionized meteor trails observed by radars. A lower limit on the influx to the mesopause region from the lidar meteors is approximately 1.6 x 10(3) sodium and 2.7 x 10(4) iron atoms per second per square centimeter, which corresponds to an annual flux of meteoric debris into the mesosphere of about 2.0 (+/-0.6) gigagrams. Because the lidars can detect only the ablation trails left by the larger meteors, the observations suggest that the actual meteoric influx may be larger than the more recently reported values, which range between 16 and 78 gigagrams per year.

Comparison of isokinetic internal and external hip rotation torques using different testing positions.

This study was undertaken by the University of Calgary Sport Medicine Centre, Physical Therapy Section. Financial support for the study was provided by a grant from the BE Schurr Memorial fund and the Canadian Physiotherapy Association (Calgary District). Information on the relative strengths of the muscles that internally and externally rotate the hip is scant. The present study used a Cybex(R) 340 isokinetic dynamometer to investigate hip rotation strength in 60 normal subjects. Subjects performed maximum internal and external hip rotation movements in each of three different testing positions. Results showed that hip rotation torques were significantly dependent on testing position (p < 0.05). Highest torques were obtained using a "seated" position, while a supine position with the knee flexed produced stronger torques than a supine position with the knee extended. Within each test position, internal rotation torques exceeded external rotation torques in all but one situation (p < 0.05). These findings contradicted previous reports that external rotation was the stronger of the two movements. Overall, the results provided valuable normative data on the relative strength proportions of the hip rotation musculature. J Orthop Sports Phys Ther 1992;16(1):43-50.

High-power single-mode diode-pumped Nd:YAG laser using a monolithic nonplanar ring resonator.

A 0.91-W single-frequency diode-pumped Nd:YAG laser at 1.06 microm is demonstrated with a TEM(00) output. We also report a 60% slope efficiency from another nonplanar monolithic ring laser with diffraction-limited, single-frequency, 1.06-microm output. Injection locking of two 0.17-W monolithic nonplanar ring resonators gave 0.34 W of single-mode power. Actively controlled injection locking of two lasers was demonstrated for indefinite periods.

Effects of wavefront sampling speed on the performance of adaptive astronomical telescopes.

Adaptive imaging systems have been developed to compensate for distortions introduced by atmospheric turbulence. Their performance is limited by the wavefront sampling rate which is constrained by the wavefront sensor processing time. This paper explores the degradation of system performance caused by limitations in the wavefront sampling rate. Errors introduced by finite image observation times are also examined. For bright images, a very short observation time per sampling period is shown to yield high system resolution. For the case of very faint images, continuous observation results in the best signal-to-noise ratio. Adaptively correcting a 4-m telescope is shown to improve the detection threshold by nearly three visual magnitudes.

Frequency fluctuations of a diode-pumped Nd:YAG ring laser.

We have measured the spectral density of the frequency fluctuations of a diode-pumped single-mode monolithic Nd:YAG ring aser by locking a Fabry-Perot resonator to the laser frequency. The fluctuations approach the limit due to spontaneous emission (the Schawlow-Townes limit) at frequencies above 80 kHz. The inherent frequency stability of these lasers makes them attractive as a potential light source for gravitational-wave interferometers.

Fast frequency tuning and phase locking of diode-pumped Nd:YAG ring lasers.

We have built a diode-pumped single-mode monolithic Nd:YAG ring-laser oscillator that can be tuned piezoelectrically over several tens of megahertz in a few microseconds. Frequency stability over 1 msec is better than 500 Hz. We have electronically phase locked two lasers for periods of minutes with phase noise of 29 mrad rms.

Frequency stability and offset locking of a laser-diode-pumped Nd:YAG monolithic nonplanar ring oscillator.

The frequency stability of laser-diode-pumped, monolithic Nd:YAG solid-state unidirectional nonplanar ring oscillators was studied by heterodyne measurements. We obtained cw single-axial- and transverse-mode power of 25 mW at 1064 nm at a slope efficiency of 19%. Two independent oscillators were offset locked at 17 MHz with frequency fluctuations of less than +/-40 kHz for periods of 8 min.

Coherent laser radar at 1.06 microm using Nd:YAG lasers.

A coherent laser radar system operating at the 1.06-microm Nd:YAG laser wavelength has been built and operated. A laser-diode-pumped monolithic ring laser served as the master oscillator. A single flash-lamp-pumped zigzag slab amplified the oscillator output to a power of 2.3 kW. Single-mode optical fiber was used to collect and mix the return signal with the local-oscillator output. Signals from clouds at a range of 2.7 km and from atmospheric aerosols at a range of 600 m were detected.

Efficient, frequency-stable laser-diode-pumped Nd:YAG laser.

We have designed and tested a laser-diode-pumped monolithic Nd:YAG oscillator. The electrical-to-optical slope efficiency was 6.5%. The frequency jitter was less than 10 kHz over a 0.3-sec period, the best frequency stability reported for a Nd:YAG laser to date.

Monolithic, unidirectional single-mode Nd:YAG ring laser.

We have built a nonplanar ring oscillator with the resonator contained entirely within a Nd:YAG crystal. When the oscillator was placed in a magnetic field, unidirectional oscillation was obtained with a pump-limited, single-axial-mode output of 163 mW.

Slab-geometry Nd:glass laser performance studies.

Slab-geometry solid-state lasers potentially provide significant performance improvements relative to conventional rod-geometry lasers. We have used a Nd:glass laser test-bed facility to verify the predicted slab-configuration advantages.

The rigid versus soft postoperative dressing controversy: a controlled study in vascular below-knee amputees.

Results of 52 consecutive below-knee amputations for lower extremity ischemia were evaluated to determine whether use of immediate fit prostheses (IPOP) instead of soft stump dressings had any bearing postoperative hospitalization time, functional recovery, postoperative pain, morbidity, and mortality in amputees. Of 34 patients receiving IPOP, 21 per cent developed stump necrosis, 21 per cent had wound infection, 26 per cent required major reamputation, and 12 per cent died within 30 days of operation. Of 18 patients treated with soft stump dressings, 17 per cent developed necrosis, 33 per cent infection, 44 per cent required reamputation, and 11 per cent died postoperatively. None of these differences was statistically significant. Mean hospitalization time and average narcotic requirements for analgesia were also similar in both groups. Fifty-six per cent of patients with IPOP and 22 per cent of those with soft dressings ultimately ambulated with prostheses (P less than 0.05). Whether or not IPOP was used had little if any effect on the early evolution of vascular amputees in this series.