Concept validation of a high dynamic range point-diffraction interferometer for wavefront sensing in adaptive optics.

The direct detection and imaging of exoplanets requires the use of high-contrast adaptive optics (AO). In these systems quasi-static aberrations need to be highly corrected and calibrated. To achieve this, the pupil-modulated point-diffraction interferometer (m-PDI) was presented in an earlier paper. This present paper focuses on m-PDI concept validation through three experiments. First, the instrument's accuracy and dynamic range are characterized by measuring the spatial transfer function at all spatial frequencies and at different amplitudes. Then, using visible monochromatic light, an AO control loop is closed on the system's systematic bias to test for precision and completeness. In a central section of the pupil with 72% of the total radius, the residual error is 7.7 nm rms. Finally, the control loop is run using polychromatic light with a spectral FWHM of 77 nm around the R-band. The control loop shows no drop in performance with respect to the monochromatic case, reaching a final Strehl ratio larger than 0.7.

Calibration of quasi-static aberrations in high-contrast astronomical adaptive optics with a pupil-modulated point-diffraction interferometer.

The direct detection and imaging of exoplanets requires the use of high-contrast adaptive optics (AO). In these systems quasi-static aberrations need to be highly corrected and calibrated. In order to achieve this, a high-sensitivity wavefront sensor, the pupil-modulated point-diffraction interferometer (m-PDI), is presented. This sensor modulates and retrieves both the phase and the amplitude of an incoming electric field. The theory behind the wavefront reconstruction, the visibility of fringes, chromatic effects and noise propagation are developed. Results show this interferometer has a wide chromatic bandwidth. For a bandwidth of Δλ = 50% in units of central wavelength, the visibility of fringes and the response of the WFS to low and high-order aberrations are almost unaffected with respect to the monochromatic case. The WFS is, in contrast, very sensitive to variations in the size of its pinhole. The size of the pinhole is shown to affect the sensor's linearity, the dynamic range and the amount of noise. Larger pinholes make the sensor less sensitive to low-order aberrations, but in turn also decrease the effects of misalignments.

Estimating stochastic noise using in situ measurements from a linear wavefront slope sensor.

It is shown how the solenoidal component of noise from the measurements of a wavefront slope sensor can be utilized to estimate the total noise: specifically, the ensemble noise variance. It is well known that solenoidal noise is orthogonal to the reconstruction of the wavefront under conditions of low scintillation (absence of wavefront vortices). Therefore, it can be retrieved even with a nonzero slope signal present. By explicitly estimating the solenoidal noise from an ensemble of slopes, it can be retrieved for any wavefront sensor configuration. Furthermore, the ensemble variance is demonstrated to be related to the total noise variance via a straightforward relationship. This relationship is revealed via the method of the explicit estimation: it consists of a small, heuristic set of four constants that do not depend on the underlying statistics of the incoming wavefront. These constants seem to apply to all situations-data from a laboratory experiment as well as many configurations of numerical simulation-so the method is concluded to be generic.

Multicenter validation of American Association for the Surgery of Trauma grading system for acute colonic diverticulitis and its use for emergency general surgery quality improvement program.

BACKGROUND: The American Association for the Surgery of Trauma (AAST) has developed a new grading system for uniform description of anatomic severity of emergency general surgery (EGS) diseases, ranging from Grade I (mild) to Grade V (severe). The purpose of this study was to determine the relationship of AAST grades for acute colonic diverticulitis with patient outcomes. A secondary purpose was to propose an EGS quality improvement program using risk-adjusted center outcomes, similar to National Surgical Quality Improvement Program and Trauma Quality Improvement Program methodologies. METHODS: This was a retrospective study of 1,105 patients (one death) from 13 centers. At each center, two reviewers (blinded to each other's assignments) assigned AAST grades. Interrater reliability was measured using κ coefficient. Relationship between AAST grade and clinical events (complications, intensive care unit use, surgical intervention, and 30-day readmission) as well as length of stay was measured using regression analyses to control for age, comorbidities, and physiologic status at the time of admission. Final model was also used to calculate observed-to-expected (O-E) ratios for adverse outcomes (death, complications, readmissions) for each center. RESULTS: Median age was 54 years, 52% were males, 43% were minorities, and 22% required a surgical intervention. Almost two thirds had Grade I or II disease. There was a high level of agreement for grades between reviewers (κ = 0.81). Adverse events increased from 13% for Grade I, to 18% for Grade II, 28% for Grade III, 44% for Grade IV, and 50% for Grade V. Regression analysis showed that higher disease grades were independently associated with all clinical events and length of stay, after adjusting for age, comorbidities, and physiology. O-E ratios showed statistically insignificant variations in risk of death, complications, or readmissions. CONCLUSION: AAST grades for acute colonic diverticulitis are independently associated with clinical outcomes and resource use. EGS quality improvement program methodology that incorporates AAST grade, age, comorbidities, and physiologic status may be used for measuring quality of EGS care. High-quality EGS registries are essential for developing meaningful quality metrics. LEVEL OF EVIDENCE: Prognostic study, level V.

Retrieval of a detached resectoscope sheath beak during a TURP.

The detachment of a resectoscope beak during transurethral resection is a rare and unpleasant event. Published techniques for its retrieval are not practical to the majority of urologists. The authors outline a novel approach for the retrieval of a detached continuous-flow resectoscope plastic beak that is quick, safe, and effective. The plastic beak is extracted at the time of detachment using standard continuous-flow resectoscope equipment. This has increased patient safety as no further loss of time and blood resulted from the delay associated with the more conventional approaches.

Granular cell tumors of the urinary bladder.

BACKGROUND: Granular cell tumors (GCTs) are extremely rare lesions of the urinary bladder with only nine cases being reported in world literature of which one was malignant. Generally believed to be of neural origin based on histochemical, immunohistochemical, and ultrastructural studies; they mostly follow a clinically benign course but are commonly mistaken for malignant tumors since they are solid looking, ulcerated tumors with ill-defined margins. MATERIALS AND METHODS: We herein report two cases of GCTs, one benign and one malignant, presenting with gross hematuria in a 14- and a 47-year-old female, respectively. RESULTS: Histopathology revealed characteristic GCTs with positive immunostaining for neural marker (S-100) and negative immunostaining for epithelial (cytokeratin, Cam 5.2, AE/A13), neuroendocrine (neuron specific enolase, chromogranin A, and synaptophysin) and sarcoma (desmin, vimentin) markers. The benign tumor was successfully managed conservatively with transurethral resection alone while for the malignant tumor, radical cystectomy, hysterectomy with bilateral salpingo-oophorectomy, anterior vaginectomy, plus lymph node dissection was done. Both cases show long-term disease free survival. CONCLUSION: We recommend careful pathologic assessment for establishing the appropriate diagnosis and either a conservative or aggressive surgical treatment for benign or localized malignant GCT of the urinary bladder, respectively.

Abdominoperineal excision of male lower urinary tract for synchronous adenocarcinoma of urethra and urinary bladder.

Urethral adenocarcinoma is the least common histologic subtype of a rare primary carcinoma of the male urethra. Its site of origin remains speculative. The scarcity of reported cases in the literature makes it difficult to define the optimal management. This report is of a 40-year-old morbidly obese man with synchronous adenocarcinoma of the bulbar urethra and bladder, treated surgically by en bloc abdominoperineal penoprostatocystectomy. The pleural recurrence, after a disease-free period of 2 years, responded well to platinum-docetaxel-based systemic chemotherapy. Synchronous occurrence of adenocarcinoma of the urethra and bladder has not been previously reported. This case also highlights the possible role of upcoming adjuvant chemotherapeutic agents.

Unenhanced helical computed tomography in the evaluation of acute flank pain.

OBJECTIVES: The purpose of this study was to determine the value of unenhanced helical computed tomography (UHCT) in the diagnosis of acute flank pain at our institution. METHODS: Two hundred and thirty-three consecutive UHCT examinations, performed for suspected renal/ureteral colic between July 2000 and August 2001 were reviewed, along with pertinent medical records. RESULTS: Ureteral calculi were identified in 148 (64%) examinations, evidence of recent passage of calculi was found in 10 (4%) and no calculi were found in 75 (32%). Thirty-two of the conservatively managed patients were excluded for inadequate follow-up. In the remaining 201 patients, sensitivity of UHCT in diagnosing calculi was 99% and specificity was 98%, while the positive predictive value was 99% and negative positive predictive value was 98%. Overall, an alternative or additional diagnosis was established in 28 (12%) patients. Upon diagnosis of ureterolithiasis on UHCT, none of the patients required additional imaging studies for confirmation. CONCLUSION: UHCT is a highly sensitive imaging modality for the detection of urinary tract calculi and obstruction.