ABSTRACT
We present the design of a portable version of our miniaturized laser heterodyne radiometer (mini-LHR) that simultaneously measures methane (CH4) and carbon dioxide (CO2) in the atmospheric column. The mini-LHR fits on a backpack frame, operates autonomously, and requires no infrastructure because it is powered by batteries charged by a folding 30 W solar panel. Similar to our earlier instruments, the mini-LHR is a passive laser heterodyne radiometer that operates by collecting sunlight that has undergone absorption by CH4 and CO2. Within the mini-LHR, sunlight is mixed with light from a distributive feedback (DFB) laser centered at approximately 1.64 µm where both gases have absorption features. The laser scans across these absorption features roughly every minute and the resulting beat signal is collected in the radio frequency (RF). Scans are averaged into half hour and hour data products and analyzed using the Planetary Spectrum Generator (PSG) retrieval to extract column mole fractions. Instrument performance is demonstrated through two deployments at significantly different sites in interior Alaska and Hawaii. The resolving power (λ/∆λ) is greater than 500,000 at 1.64 µm with precisions of better than 20 ppb and 1 ppm for CH4 and CO2, respectively. Because mini-LHR instruments are portable and can be co-located, they can be used to characterize bias between larger, stationary, column observing instruments. In addition, mini-LHRs can be deployed quickly to respond to transient events such as methane leaks or can be used for field studies targeting geographical regions.
ABSTRACT
Three hundred and sixty patients underwent hysteroscopy before entering the IVF program. The procedure was successful in 332 patients; obstructive tubal disease was present in 247 (70%); 148 showed uterine abnormalities (44.5%) such as endometrial polyps, adhesions, hypoplasia, malformations, or severe cervical stenosis; 114 patients had normal hysterographic findings, in whom hysteroscopy revealed a false-negative rate of 36.8%. In 281 patients (84.6%) hysteroscopy was carried out under general anesthesia, in most cases associated with laparoscopy. There were no anesthetic complications, uterine perforations or other significant problems. In an IVF program, hysteroscopic evaluation can reduce the failure rate due to intra-uterine abnormalities. Hysteroscopy, which permits one to optimize an IVF attempt, becomes an essential procedure before introducing a patient into an IVF program.
