Electron impact electronic excitation of benzene: Theory and experiment.

We report experimental differential cross sections (DCSs) for electron impact excitation of bands I to V of benzene at incident energies of 10, 12.5, 15, and 20 eV. They are compared to calculations using the Schwinger multichannel method while accounting for up to 437 open channels. For intermediate scattering angles, the calculations reveal that the most intense band (V) emerges from surprisingly similar contributions from all its underlying states (despite some preference for the dipole-allowed transitions). They further shed light on intricate multichannel couplings between the states of bands I to V and higher-lying Rydberg states. In turn, the measurements support a vibronic coupling mechanism for excitation of bands II and IV and also show an unexpected forward peak in the spin-forbidden transition accounting for band III. Overall, there is decent agreement between theory and experiment at intermediate angles and at lower energies and in terms of the relative DCSs of the five bands. Discrepancies between the present and previous experiment regarding bands IV and V draw attention to the need of additional experimental investigations. We also report measured DCSs for vibrational excitation of combined C-H stretching modes.

The role of pronouns in young children's acquisition of the English transitive construction.

Two studies investigating the linguistic representations underlying English-speaking 2 1/2-year-olds' production of transitive utterances are reported. The first study was a training study in which half the children heard utterances with full nouns as agent and patient, and half the children heard utterances with both pronouns (i.e., He's [verb]-ing it) and also full nouns. In subsequent testing, only children who had been trained with pronouns and nouns were able to produce a transitive utterance creatively with a nonce verb. The second study reported an analogous set of findings, but in comprehension. Together, the results of these 2 studies suggest that English-speaking children build many of their early linguistic constructions around certain specific lexical or morphological items and patterns, perhaps especially around particular pronoun configurations.

Application of standardized quality control procedures to open-path Fourier transform infrared data collected at a concentrated swine production facility.

Open-path Fourier transform infrared (OP/FT-IR) spectrometry was used to measure the concentrations of ammonia, methane, and other atmospheric gases at a concentrated swine production facility. A total of 2200 OP/FT-IR spectra were acquired along nine different monitoring paths during an 8-day period between January 11 and 22, 1999. Standardized quality control (QC) procedures were applied to the archived OP/FT-IR spectra to verify that the instrument was set up and operating properly during the field study and to identify outliers in the concentration data. These QC procedures included measuring the random baseline noise, the signal strength, and the relative single-beam intensity in selected wavenumber regions; inspecting the archived spectra for wavenumber shifts, changes in resolution, and evidence of detector saturation; and examining time series plots of the target gas concentrations and the uncertainty values reported by the classical least-squares (CLS) analysis. Application of these QC procedures to the archived spectra identified 252 potential outliers. After a careful review of the original spectra, 41 of the 252 suspected outliers were designated as actual outliers. Of the QC criteria used during this study, the uncertainty values reported by the CLS analysis were the most reliable indicators of actual outliers.

Real-time and integrated measurement of potential human exposure to particle-bound polycyclic aromatic hydrocarbons (PAHs) from aircraft exhaust.

We used real-time monitors and low-volume air samplers to measure the potential human exposure to airborne polycyclic aromatic hydrocarbon (PAH) concentrations during various flight-related and ground-support activities of C-130H aircraft at an Air National Guard base. We used three types of photoelectric aerosol sensors (PASs) to measure real-time concentrations of particle-bound PAHs in a break room, downwind from a C-130H aircraft during a four-engine run-up test, in a maintenance hangar, in a C-130H aircraft cargo bay during cargo-drop training, downwind from aerospace ground equipment (AGE), and in a C-130H aircraft cargo bay during engine running on/off (ERO) loading and backup exercises. Two low-volume air samplers were collocated with the real-time monitors for all monitoring events except those in the break room and during in-flight activities. Total PAH concentrations in the integrated-air samples followed a general trend: downwind from two AGE units > ERO-loading exercise > four-engine run-up test > maintenance hangar during taxi and takeoff > background measurements in maintenance hangar. Each PAH profile was dominated by naphthalene, the alkyl-substituted naphthalenes, and other PAHs expected to be in the vapor phase. We also found particle-bound PAHs, such as fluoranthene, pyrene, and benzo[a]pyrene in some of the sample extracts. During flight-related exercises, total PAH concentrations in the integrated-air samples were 10-25 times higher than those commonly found in ambient air. Real-time monitor mean responses generally followed the integrated-air sample trends. These monitors provided a semiquantitative temporal profile of ambient PAH concentrations and showed that PAH concentrations can fluctuate rapidly from a baseline level < 20 to > 4,000 ng/m(3) during flight-related activities. Small handheld models of the PAS monitors exhibited potential for assessing incidental personal exposure to particle-bound PAHs in engine exhaust and for serving as a real-time dosimeter to indicate when respiratory protection is advisable.

High-dose-rate postoperative vaginal cuff irradiation alone for stage IB and IC endometrial cancer.

PURPOSE: To evaluate the effectiveness of postoperative high-dose-rate (HDR) vaginal cuff irradiation alone (1500 cGy in 3 fractions) in patients with Stage Ib and Ic endometrial cancer. METHODS AND MATERIALS: This is a retrospective review of 102 patients with Stage Ib and Ic endometrial cancer treated with a hysterectomy and postoperative HDR intracavitary therapy alone during the period of 1/1/90-12/31/96. Each patient received 1500 cGy in 3 weekly treatments, dosed to a depth of 0.5 cm. Pathologic features such as depth of invasion, tumor grade, lower uterine segment (LUS) involvement, and lymphvascular invasion (LVI) were evaluated for their impact on recommended postoperative treatment. All survival curves were generated utilizing Kaplan-Meier methods and all statistical comparisons were via a Wilcoxon rank sum test. RESULTS: The 5-year actuarial overall survival (OS) is 84% and the 5-year disease-free survival (DFS) is 93%. Locoregional disease control (pelvic control) was excellent with 97% of the patients free of pelvic disease at 5 years. Of the three pelvic failures only one was in the vaginal cuff. LVI, LUS involvement, Grade 3 and/or outer third myometrial involvement were identified in 41 patients. Thirty-one of these patients underwent a lymphadenectomy and there were two regional failures within this increased-risk group. CONCLUSIONS: We obtained an excellent level of locoregional control with minimal morbidity and minimal time commitment for treatment with vaginal HDR brachytherapy alone. Our dose per fraction and total dose is lower than most reported series and there is no apparent loss in locoregional control. In addition, intermediate-risk patients and patients with an increased risk of recurrence (Grade 3, outer third myometrial involvement, LVI, LUS) may be treated with cuff irradiation alone, after surgical staging and a negative lymphadenectomy.

The virtues and pitfalls of minimally invasive surgery for gynecological malignancies: an update.

Operative laparoscopy is still jockeying for its place in the surgical management of gynecological malignancies. Its usefulness in staging these malignancies continues to be investigated, as does its ability to convert abdominal procedures to vaginal procedures. Recent articles also address the role of operative laparoscopy in less common procedures, as well as the curiosity of investigators to gain a better understanding of the 'consequences' of operative laparoscopy by using animal models. The reader is updated by a review of the reports published over the past year and a half.

Preliminary technique of laparoscopic extraperitoneal infrarenal paraaortic lymphadenectomy in the porcine model.

We developed an extraperitoneal approach to laparoscopic infrarenal paraaortic lymphadenectomy in the porcine model, with the ultimate aim of shortening the long learning curve of this procedure in humans. Surgery was performed on four females pigs with three 10-mm cannulas placed along the midaxillary line in prone position. The first and second pigs underwent subsequent laparotomy to evaluate the adequacy of lymph node dissection and complications. In all four animals, complete infrarenal paraaortic lymphadenectomy was successful, retrieving between 6 and 11 lymph nodes (average 9). Laparotomy in the first two animals confirmed adequate lymphadenectomy. No complications occurred. Operating time was shortened dramatically with each procedure (180, 120, 50, 40 min). In the porcine model this approach provides excellent exposure to the entire paraaortic lymphatic chain, is safe, and has a remarkably short learning curve. Development of a similar technique in humans may have significant advantages, including short learning curve, feasibility in obese patients and those with peritoneal adhesions, decreased adhesion formation, and reduced bowel complications associated with postoperative adjuvant irradiation. Further studies are indicated.

Transabdominal cerclage: a laparoscopic approach.

BACKGROUND: The placement of a transabdominal cervical cerclage has been regarded as considerably more morbid than a transvaginal cerclage, in part due to the need for two laparotomies. We describe a technique for the laparoscopic placement and removal of a transabdominal cerclage. CASES: Two cases of women with insufficient cervical tissue to place a transvaginal cerclage were managed with a transabdominal cerclage. In one case, the cerclage was placed laparoscopically; in the other, the band was removed, facilitating uterine evacuation following the diagnosis of a missed abortion. In both cases a laparotomy was avoided. CONCLUSION: Laparoscopic placement and removal of a transabdominal cerclage are promising options in the treatment of an incompetent cervix.

Concentrations of carotenoids, tocopherols, and retinol in paired plasma and cervical tissue of patients with cervical cancer, precancer, and noncancerous diseases.

Paired blood (collected after an overnight fast) and cervical tissue (cancerous, precancerous, and noncancerous) samples were obtained from 87 patients (age, 21-86 years) who had a hysterectomy or biopsy due to cervical cancer, precancer (cervical intraepithelial neoplasia I, II, and III), or noncancerous diseases. The samples were analyzed using high-performance liquid chromatography for 10 micronutrients (lutein, zeaxanthin, beta-cryptoxanthin, lycopene, alpha-carotene, beta-carotene, cis-beta-carotene, alpha-tocopherol, gamma-tocopherol, and retinol). The results indicated that: (a) among the three patient groups, the mean plasma concentrations of all micronutrients except gamma-tocopherol were lowest in the cancer patients; however, the mean tissue concentrations of the two tocopherols and certain carotenoids were highest in the cancerous tissue; and (b) among the 10 micronutrients, only the concentrations of beta-carotene and cis-beta-carotene were lower in both the plasma and tissue of cancer and precancer patients than in those of noncancer controls. These results suggest that: (a) not all of the micronutrient concentrations in plasma reflect the micronutrient concentrations in cervical tissue; thus, in some cases, it may be necessary to measure the tissue micronutrient concentrations to define the role of the micronutrients in cervical carcinogenesis; and (b) maintaining an adequate plasma and tissue concentration of beta-carotene may be necessary for the prevention of cervical cancer and precancer.

Y2K, embedded chips, casualty hazards and due diligence in healthcare risk management.

Y2K raises challenges for healthcare risk managers that go beyond information technology issues. This article explains that (1) too little public attention is being paid to equipment which may well have Y2K faults and (2) few standards have been articulated for dealing with problems. Healthcare risk managers therefore must return to basic due diligence principles and develop their own standards and protocols. The article explains how to do due diligence and outlines suggested steps for dealing with the non-information technology side of compliance due diligence.

Major retroperitoneal vascular injury during laparoscopic surgery.

We sought to assess the outcome of large retroperitoneal vascular injury that occurred during operative laparoscopy but was not related to trocar or Veress needle injury. We conducted a retrospective review of cases operated and reviewed by our centres. Eight cases were identified. Four women were undergoing lymphadenectomy, where vascular injury is a recognized risk. Distorted anatomy was a compounding factor in three of the remaining four patients who were undergoing intraperitoneal procedures. The injuries involved the inferior vena cava (n = 2), the right external iliac artery (n = 2), the left external iliac artery (n = 1), the right external iliac vein (n = 1), the hypogastric artery (n = 1) and the inferior mesenteric artery (n = 1). Injuries were caused by unipolar electrode (n = 1), electrosurgical scissors (n = 3), sharp scissors (n = 2) and CO(2) laser (n = 2). The vessel injury was repaired at laparotomy in four women. The other four cases were managed laparoscopically. Transfusion attributable to the vascular injury occurred in two cases. The outcome in all cases was good, except for one in which the patient died. These cases demonstrate that all energy sources used without proper understanding and caution can cause significant vascular injury. The adequacy and safety of laparoscopic control of major vessel bleeding should be investigated further and consultation with a vascular surgeon should be considered in all cases.

Laparoscopic staging of endometrial cancer: the learning experience.

OBJECTIVE: To evaluate our learning-curve experience with laparoscopic management of endometrial carcinoma. METHODS: Retrospective review of our first 125 patients with endometrial cancer who were managed laparoscopically. The patient population was reviewed in a chronological manner, noting patient demographics, operative procedure and times, estimated blood loss, hospital stay, complications, and pathology. RESULTS: Overall, the mean age was 68.6 years (range 29-89), the mean weight was 160 pounds (range 97-328), and the mean Quetelet index was 27.8 (range 17.8-56.4). Metastatic disease was discovered in 28.8% (17/59) of patients with grade 2 or 3 lesions. There was no statistically significant variation in any of these parameters throughout the study. Operative times for staging without lymphadenectomy decreased significantly from a mean of 163 minutes to 99 minutes (p < .001). Operative times for staging with lymphadenectomy decreased from a mean of 196 minutes to 128 minutes (p < 0.02). Hospital stay decreased from a mean of 3.2 days in the first quarter of our study to 1.8 days (p < .0001). The overall average complication rate of 4% (two enterotomies, two cystotomies, and a transected ureter) did not vary. However, the rate of conversion to laparotomy dropped significantly from 8% (2/25) to 0% (0/100). CONCLUSIONS: We found that operative times and hospital stays for laparoscopic staging of endometrial cancer continued to drop after 125 cases. While the ability to detect metastatic disease and the rate of major complications appear unrelated to length of the operator experience, the conversion rate to laparotomy decreases with operator experience. Learning-curve parameters must be recognized by physicians, patients, and researchers for a host of reasons.

Laparoscopic bowel injuries among gynecologic patients.

Bowel injury is an uncommon but recognized risk of operative laparoscopy. Because of the significant morbidity that can occur with this complication, it is important that clinicians be aware of its incidence, presentation, and management. This manuscript outlines the common causes of bowel injury, including herniation and traumatic bowel perforation. Management of laparoscopic bowel injuries is discussed and recommendations are made for avoidance of such complications.

Laparoscopic management of suspicious adnexal masses.

OBJECTIVE: Our aim was to evaluate the feasibility and applicability of operative laparoscopy in the management of adnexal masses that do not meet the standard serum CA 125 and ultrasonographic criteria for benignity. STUDY DESIGN: One hundred thirty-eight patients underwent operative laparoscopy for removal of suspicious adnexal masses. The CA 125 level was > 35 mlU/ml in 39 of 138 (28%) patients; ultrasonographic findings were abnormal in 127 of 138 (92%); masses were > 10 cm in 43 of 138 (32%) of patients. RESULTS: Malignancies were discovered in 14% (19/138) of patients. Eight percent (11/138) of the procedures were converted to laparotomy, six because of inability to dissect the mass laparoscopically and five for staging or debulking of carcinoma. Operative times ranged from 25 to 210 minutes, with a mean of 86. Three major complications were encountered-an enterotomy and a lacerated vena cava, both of which were repaired laparoscopically, and a small bowel herniation through a lateral port site that required reoperation. Hospital stays ranged from 0 to 11 days, with a mean of 1.5. In two patients with "apparent" stage I adnexal carcinomas recurrence was diagnosed 6 and 38 months after surgery. CONCLUSIONS: Laparoscopic management of suspicious adnexal masses is technically feasible, with a low rate of morbidity and a short hospital stay. Adnexal carcinomas can be identified and managed appropriately with staging and complete resection as indicated.

Major Vessel Injury During Advanced Laparoscopic Surgery

Eight cases of large vessel laceration occurred during operative laparoscopy, but were not related to cannula or Veress needle injury. Four injuries were managed at laparoscopy. One patient was operated on by us. We reviewed four cases for colleagues, and the remainder were subject to litigation. Four women were undergoing lymph node dissection and three others had endometriosis or adhesions that obliterated the normal anatomy. The injury involved the inferior vena cava in two women, the right external iliac artery in four, and the left hypogastric and inferior mesenteric artery in one woman each. Vascular lacerations were caused by unipolar electrosurgery in two patients and by the carbon dioxide laser in two. In the remaining four women the injury to the artery or vein occurred during sharp dissection. The vessel injury was repaired by the conventional open technique in four women. The other four were managed laparoscopically, two by applying metal clips on the vessel wall and one with bipolar electrocoagulation. The outcome in all patients was good except for one, who died.

Laparoscopic management of benign cystic teratomas during pregnancy.

OBJECTIVE: Our purpose was to evaluate the surgical management and outcome of laparoscopic removal of benign cystic teratomas during pregnancy. STUDY DESIGN: The records of women with benign cystic teratomas who were managed with operative laparoscopy during pregnancy were reviewed. RESULTS: Twelve women had laparoscopic removal of a benign cystic teratoma during pregnancy. Gestational ages at surgery ranged from 9 to 17 weeks, with a mean of 14 weeks. Cyst size ranged from 5 to 13 cm, with a mean of 8.5 cm. Intraoperative rupture of the cyst occurred in 10 of 12 (93%) women. No patient had evidence of chemical peritonitis. The mean operating time was 87 minutes and the mean postoperative hospital stay was 44 hours. No intraoperative or postoperative maternal or fetal complications occurred. CONCLUSIONS: Laparoscopic removal of a benign cystic teratoma of the ovary may be safely accomplished during pregnancy. In spite of a significant risk of cyst rupture, careful operative technique followed by copious irrigation of the pelvis may avoid chemical peritonitis and potential adverse sequelae.

Laparoscopic ovarian cystectomy for a benign teratoma in a 10-year-old girl.

A 10-year-old girl was diagnosed with an 8-cm mature cystic teratoma. An outpatient ovary-conserving cystectomy was performed, and the girl recovered fully in 24 hours. We suggest that laparoscopy can be effective in the conservative management of some gynecologic disorders in properly selected children.

A simple suturing technique for laparoscopic ligation of vascular pedicles.

We report on the performance of 348 adnexectomies and 35 uterine artery ligations for both benign and malignant disease using a simple laparoscopic suturing technique. Only 5-mm ports are required, and there was no morbidity directly associated with this approach. The procedure can be performed quickly, is relatively inexpensive, and allows hysterectomy and oophorectomy to be performed without bipolar electrocautery.