Quantum light from a whispering-gallery-mode disk resonator.

Optical parametric down-conversion has proven to be a valuable source of nonclassical light. The process is inherently able to produce twin-beam correlations along with individual intensity squeezing of either parametric beam, when pumped far above threshold. Here, we present for the first time the direct observation of intensity squeezing of -1.2 dB of each of the individual parametric beams in parametric down-conversion by use of a high quality whispering-gallery-mode disk resonator. In addition, we observed twin-beam quantum correlations of -2.7 dB with this cavity. Such resonators feature strong optical confinement and offer tunable coupling to an external optical field. This work exemplifies the potential of crystalline whispering-gallery-mode resonators for the generation of quantum light. The simplicity of this device makes the application of quantum light in various fields highly feasible.

Entangling different degrees of freedom by quadrature squeezing cylindrically polarized modes.

Quantum systems such as, for example, photons, atoms, or Bose-Einstein condensates, prepared in complex states where entanglement between distinct degrees of freedom is present, may display several intriguing features. In this Letter we introduce the concept of such complex quantum states for intense beams of light by exploiting the properties of cylindrically polarized modes. We show that already in a classical picture the spatial and polarization field variables of these modes cannot be factorized. Theoretically it is proven that by quadrature squeezing cylindrically polarized modes one generates entanglement between these two different degrees of freedom. Experimentally we demonstrate amplitude squeezing of an azimuthally polarized mode by exploiting the nonlinear Kerr effect in a specially tailored photonic crystal fiber. These results display that such novel continuous-variable entangled systems can, in principle, be realized.

Naturally phase-matched second-harmonic generation in a whispering-gallery-mode resonator.

We demonstrate for the first time natural phase matching for optical frequency doubling in a high-Q whispering-gallery-mode resonator made of lithium niobate. A conversion efficiency of 9% is achieved at 30 microW in-coupled continuous wave pump power. The observed saturation pump power of 3.2 mW is almost 2 orders of magnitude lower than the state-of-the-art value. This suggests an application of our frequency doubler as a source of nonclassical light requiring only a low-power pump, which easily can be quantum noise limited. Our theoretical analysis of the three-wave mixing in a whispering-gallery-mode resonator provides the relative conversion efficiencies for frequency doubling in various modes.

Low-threshold optical parametric oscillations in a whispering gallery mode resonator.

In whispering gallery mode (WGM) resonator light is guided by continuous total internal reflection along a curved surface. Fabricating such resonators from an optically nonlinear material one takes advantage of their exceptionally high quality factors and small mode volumes to achieve extremely efficient optical frequency conversion. Our analysis of the phase-matching conditions for optical parametric down-conversion (PDC) in a spherical WGM resonator shows their direct relation to the sum rules for photons' angular momenta and predicts a very low parametric oscillation threshold. We realized such an optical parametric oscillator (OPO) based on naturally phase-matched PDC in lithium niobate. We demonstrated a single-mode, strongly nondegenerate OPO with a threshold of 6.7 µW and linewidth under 10 MHz. This work demonstrates the remarkable capabilities of WGM-based OPOs.

Reduction of guided acoustic wave Brillouin scattering in photonic crystal fibers.

Guided acoustic wave Brillouin scattering (GAWBS) generates phase and polarization noise of light propagating in glass fibers. This excess noise affects the performance of various experiments operating at the quantum noise limit. We experimentally demonstrate the reduction of GAWBS noise in a photonic crystal fiber in a broad frequency range by tailoring the acoustic modes using the photonic also as a phononic crystal. We compare the noise spectrum to the one of a standard fiber and observe a tenfold noise reduction in the frequency range up to 200 MHz. Based on our measurement results as well as on numerical simulations, we establish a model for the reduction of GAWBS noise in photonic crystal fibers.

Effects of pelvic floor muscle training on strength and predictors of response in the treatment of urinary incontinence.

AIMS: The objectives of this study were (1) to determine the effect of training on pelvic floor muscle strength; (2) to determine whether changes in pelvic floor muscle strength correlate with changes in continence; and (3) to determine whether demographic characteristics, clinical incontinence severity indices, or urodynamic measures predict response to pelvic floor muscle training. METHODS: One hundred thirty-four women with urinary incontinence (95=genuine stress incontinence [GSI]; 19=detrusor instability [DI]; 20=mixed incontinence [GSI+DI]) were randomized to pelvic floor muscle training (n=67) or bladder training (n=67). Urinary diaries, urodynamic evaluation, and vaginal pressure measurements by using balloon manometry were performed at baseline and after 12 weeks of therapy. Primary outcome measures consisted of incontinent episodes per week and vaginal pressure measurements. RESULTS: Both treatment groups had a reduction in incontinent episodes (P

The routine use of cystoscopy with the Burch procedure.

OBJECTIVE: We sought to determine the incidence of unsuspected injury to the lower urinary tract as detected by intraoperative cystoscopy when the Burch procedure is performed. STUDY DESIGN: We reviewed the records of 181 women who underwent pelvic surgery, which included a Burch retropubic urethropexy for genuine stress urinary incontinence, between Jan 1, 1998, and Dec 31, 1999. All patients underwent intraoperative cystoscopy at the completion of the Burch procedure after the administration of intravenous indigo carmine dye. RESULTS: There were 6 (3.3%) injuries to the lower urinary tract. Five of the injuries were cystotomies that had been recognized during operation. One obstructed left ureter was detected by cystoscopy and relieved by the release of left paravaginal repair sutures. No unsuspected injuries that were detected by cystoscopy were attributable to the Burch procedure. CONCLUSIONS: The lower urinary tract injury rate was 3.3%. All but one injury was recognized before cystoscopy. The one injury was attributed to concomitant paravaginal repair and not to the Burch procedure.

A comparison of urethral profilometry using microtip and fiberoptic catheters.

This paper compares urethral profilometry measurements using two different types of catheter: the Millar microtip transducer and the FST fiberoptic catheter. Outcome variables were functional urethral length (FUL), maximum urethral closure pressure (MUCP), and mean pressure/transmission ratio (PTR). Thirty women presenting to the urodynamics laboratory with symptoms of stress urinary incontinence were evaluated with both catheters. All subjects underwent two passive urethral pressure profiles and two dynamic (cough) urethral pressure profiles with each catheter. For FUL and MUCP, the means of the two passive measurements were compared between catheters. For PTR, the means of the two dynamic measurements were compared between catheters. There was no difference in FUL between the two catheter types. The FST measurements of MUCP and PTR were lower than the microtip measurements. Twenty percent of patients would have been diagnosed with low-pressure urethra with the FST catheter, but not with the microtip catheter. Caution must be used when applying urethral measurements taken with the fiberoptic catheters to standards set with microtip catheters.

Understanding lower urinary tract function in women soon after bladder neck surgery. Continence Program for Women Research Group.

The aim of this work was to correlate anatomic and urodynamic measures with function following bladder neck surgery. Eighty-seven women who underwent bladder neck surgery at two tertiary academic medical centers in the southeastern U.S. were studied in this prospective outcomes analysis. Preoperative and 6-week and 6-month postoperative status was assessed with urodynamic testing, physical examination, and condition-specific quality of life instruments. Correlations of dynamic urethral obstruction (quantified by pressure transmission ratio, PTR, determinations) and urethral support (quantified by urethral axis measurements) with functional status were determined. At 6 weeks, 50% of the subjects with inadequate dynamic obstruction (PTR < 90%) had genuine stress incontinence (GSI) compared to 5% of those with PTR >/= 90% (P = .00002). Of those with excessive obstruction (PTR > 110%), 32% had detrusor instability (DI) and 47% had emptying phase dysfunction (EPD) compared to 6% and 24%, respectively, of those with PTR /= 90% but

The effect of bladder training, pelvic floor muscle training, or combination training on urodynamic parameters in women with urinary incontinence. Continence Program for Women Research Group.

The purpose of this study was to compare the effect of three conservative interventions: pelvic floor muscle training, bladder training, or both, on urodynamic parameters in women with urinary incontinence. Two hundred four women with genuine stress incontinence (GSI) or detrusor instability with or without GSI (DI +/- GSI) participated in a two-site trial comparing pelvic floor muscle training, bladder training, or both. Patients were stratified based on severity of urinary incontinence, urodynamic diagnosis, and treatment site, then randomized to a treatment group. All women underwent a comprehensive standardized evaluation including multi-channel urodynamics at the initial assessment and at the end of 12 weeks of therapy. Analysis of covariance was used to detect differences among treatment groups on urodynamic parameters. Post-treatment evaluations were available for 181 women. No differences were found among treatments on the following measurements: maximum urethral closure pressure, mean urethral closure pressure, maximum Kegel urethral closure pressure, mean Kegel urethral closure pressure, functional urethral length, pressure transmission ratios, straining urethral axis, first sensation to void, maximum cystometric capacity, and the MCC minus FSV. The effect of treatment did not differ by urodynamic diagnosis. Behavioral therapy had no effect on commonly measured urodynamic parameters. The mechanism by which clinical improvement occurs remains unknown. Neurourol. Urodynam. 18:427-436, 1999.

Relationship between urethral and vaginal pressures during pelvic muscle contraction. The Continence Program for Women Research Group.

Condensation is the performance of an effective pelvic muscle contraction increases urethral and vaginal pressures and is independent of demographic, clinical, and urodynamic factors. Our objective was to examine the relationship between urethral closure pressure and vaginal pressure during a pelvic muscle contraction in minimally trained women. Our secondary aim was to determine whether demographic, clinical, or urodynamic factors predict pelvic muscle contraction performance. Two hundred two women with urinary incontinence underwent multichannel urodynamic evaluation, including urethral profilometry and measurement of vaginal pressure during pelvic muscle contraction. One hundred forty-four women were diagnosed with genuine stress incontinence, 28 with detrusor instability, and 30 with mixed incontinence. Urethral and vaginal pressures correlated significantly during pelvic muscle contraction (P < or = 0.006). The ability to perform an adequate pelvic muscle contraction was independent of subject age, parity, hormonal or hysterectomy status, clinical severity, urethral support, and urethral profilometry measures (P > or = 0.42).

Correlation of urodynamic measures of urethral resistance with clinical measures of incontinence severity in women with pure genuine stress incontinence. The Continence Program for Women Research Group.

OBJECTIVE: Our aim was to correlate multiple measures of urethral resistance with five clinical measures of incontinence severity in women with pure genuine stress incontinence. STUDY DESIGN: Seventy-five women with pure genuine stress incontinence underwent passive and dynamic urethral pressure profilometry and Valsalva leak point pressure determinations. The standardized and validated measures of incontinence severity included (1) the number of incontinent episodes, (2) the number of continence pads used recorded in a prospective 1-week urinary dairy, (3) grams of fluid loss on a pad quantitation test, and (4) two condition-specific quality-of-life scales, the urogenital distress inventory and the incontinence impact questionnaire. The urodynamic and severity measures were compared with Pearson product-moment correlation analysis. RESULTS: There were no significant correlations between dynamic urethral pressure profile pressure transmission ratios and any measure of incontinence severity. Passive urethral pressure profile variables correlated significantly with incontinence episodes and pad use. Valsalva leak point pressures correlated significantly with pad use and quantitation testing. None of the urodynamic measurements was significantly correlated with either of the quality-of-life scales, but our power to demonstrate a correlation was limited. CONCLUSIONS: Both passive urethral pressure profile measures and Valsalva leak point pressures correlate with some severity measures of genuine stress incontinence. Although inefficient pressure transmission during stress is critical to the pathogenesis of genuine stress incontinence, the severity of the pressure transmission defect is not related to clinical severity. Conversely, impairment of intrinsic urethral resistance is not essential to the pathogenesis of genuine stress incontinence, but the degree of sphincteric impairment is related to severity once the condition exists.

Valsalva leak point pressures in women with genuine stress incontinence: reproducibility, effect of catheter caliber, and correlations with other measures of urethral resistance. Continence Program for Women Research Group.

OBJECTIVES: The Valsalva leak point pressure has been promoted as an alternative to urethral pressure profilometry as a measure of urethral resistance in women with genuine stress incontinence. Our aims were to evaluate the reproducibility of the Valsalva leak point pressure, to assess the effect of catheter caliber on the Valsalva leak point pressure, and to compare vesical Valsalva leak point pressure to other measures of urethral resistance. STUDY DESIGN: Sixty consecutive women with genuine stress incontinence underwent duplicate Valsalva leak point pressure determinations by use of 8F and 3F vesical and 8F vaginal catheters. Subjects also underwent a standard resting urethral pressure profilometry, cough leak point pressure determinations, and pressure-flow micturition studies. RESULTS: Leakage was demonstrated on both Valsalva maneuvers in approximately 80% of subjects with both catheters. In subjects who leaked with both strains there was an extremely high correlation between the test-retest Valsalva leak point pressure within both catheters. The intercatheter correlation between the 8F and 3F Valsalva leak point pressures was significant but much weaker than the intracatheter correlations; 8F Valsalva leak point pressures were significantly higher than 3F Valsalva leak point pressures, although there were individual exceptions to this observation. Urethral pressure profilometry measures and micturition opening pressures were poorly correlated with Valsalva leak point pressure. Cough and vaginal Valsalva leak point pressures were significantly correlated with vesical Valsalva leak point pressure, but cough leak point pressures were significantly higher and vaginal Valsalva leak point pressures were significantly lower than the vesical Valsalva leak point pressure. CONCLUSIONS: Valsalva leak point pressure is a simple and reproducible technique for evaluating urethral resistance in women with genuine stress incontinence. However, variations in Valsalva leak point pressure measurement must be precisely described, standardized, and validated before a technique can be advocated for clinical use.

Comparison of "subjective" and "objective" measures of severity of urinary incontinence in women. Program for Women Research Group.

The aims of this study were to compare "subjective" measures of severity of urinary incontinence to similar "objective" measures, establish their statistical correlation, and determine the effect of specific urodynamic diagnosis on such correlations. Baseline data was available from 265 women entered into a clinical trial studying pharmacologic and behavioral interventions for urinary incontinence. The "subjective" measures of incontinence were obtained by patient recall during history taking and included: the number of incontinent episodes in 1 week, the number of perineal pads used during 1 week, and the number of clothing changes required due to wetness. The "objective" measures of severity included: the number of incontinent episodes per week as recorded on a 7-day diary, the number of perineal pads used per week, also recorded on a diary, and the amount of fluid lost during a standardized pad test. Analysis consisted of Pearson correlations and linear regressions to determine equations for the prediction of objective measurement on the basis of the corresponding subjective measure. Significant positive correlations were seen between "subjective" and "objective" measurements for the comparisons of number of weekly incontinent episodes (R = 0.63), and for the weekly number of pads used (R = 0.81). The comparison between the number of clothing changes and the amount of fluid lost during pad testing was also significantly but less strongly correlated (R = 0.24). For the correlations between subjective and objective determinations of urinary incontinent episodes and for those between clothing changes and pad testing, the urodynamic diagnosis had no effect on the correlation coefficients, but did have a statistically significant effect on the intercept.(ABSTRACT TRUNCATED AT 250 WORDS)

Pelvic relaxation of the anterior compartment.

Defects in the support of the anterior pelvic compartment result in a number of anatomic and physiologic problems in women. Recently, an emphasis has been placed on the importance of thorough evaluation of such defects so that sufficient and hopefully permanent repair of all defects can be performed. Newer applications of radiologic techniques aid in identifying and quantifying pelvic floor defects. Possible surgical approaches to pelvic defect repair are reviewed, as are newer techniques such as peri-urethral injections and laparoscopic colposuspension.