Calibration of a multi-anvil high-pressure apparatus to simulate planetary interior conditions.

This paper presents the setup and pressure calibration of an 800-ton multi-anvil apparatus installed at the Vrije Universiteit (Amsterdam, the Netherlands) to simulate pressure-temperature conditions in planetary interiors. This high-pressure device can expose cubic millimeter sized samples to near-hydrostatic pressures up to ~ 10 GPa and temperatures exceeding 2100 °C. The apparatus is part of the Distributed Planetary Simulation Facility (DPSF) of the EU Europlanet 2020 Research Infrastructure, and significantly extends the pressure-temperature range that is available through international access to this facility.

Magnetohydrodynamic interference with the edge pedestal motional Stark effect diagnostic on DIII-D.

Accurate measurement of internal magnetic field direction using motional Stark effect (MSE) polarimetry in the edge pedestal is desired for nearly all tokamak scenario work. A newly installed 500 kHz 32-channel digitizer on the MSE diagnostic of DIII-D allows full spectral information of the polarimeter signal to be recovered for the first time. Fourier analysis of this data has revealed magnetohydrodynamic (MHD) fluctuations in the plasma edge pedestal at ρ ≥ 0.92. By correlating edge localized mode fluctuations seen on lock-in amplifier outputs with MSE spectrograms, it has been shown that edge pedestal tearing mode fluctuations cause interference with MSE second harmonic instrument frequencies. This interference results in unrecoverable errors in the real-time polarization angle measurement that are more than an order of magnitude larger than typical polarimeter uncertainties. These errors can cause as much as a 38% difference in local q. By using a redundant measure of the linear polarization found at the fourth harmonic photo-elastic modulator (PEM) frequency, MHD interference can be avoided. However, because of poorer signal-to-noise the fourth harmonic signal computed polarization angle shows no improvement over the MHD polluted second harmonics. MHD interference could be avoided in future edge pedestal tokamak polarimeters by utilizing PEMs with higher fundamental frequencies and a greater separation between their frequencies.

Silicide-induced multi-wall carbon nanotube growth on silicon nanowires.

A novel multi-walled carbon nanotube (MWNT) growth process is reported based on carbon incorporation in a nickel catalyst layer deposited via plasma-enhanced atomic layer deposition (PEALD) on silicon nanowires and silicon wafer substrates. As-deposited PEALD Ni films containing relatively high amounts of carbon (>18 at.%) were observed to promote the growth of MWNTs upon post-deposition rapid thermal annealing. For these films the carbon originated from the ALD precursor ligand and MWNT growth occurred in the absence of a vapor-phase carbon feedstock. MWNT growth relied on the formation of nickel silicide at the PEALD Ni/Si interface which increased the local carbon concentration in the Ni film sufficiently to promote carbon saturation/precipitation at Ni catalyst grains and nucleate MWNT growth. Similar MWNT growth from annealed PEALD Ni films was not observed on SiO(2)-coated Si wafer substrates, consistent with the role of silicidation in the observed Ni-catalyzed MWNT growth on Si. This MWNT growth mode requires neither the catalytic decomposition of a gaseous hydrocarbon source nor the high-temperature pyrolysis of metallocene materials and purposely avoids a catalyst diffusion barrier at the Si substrate, commonly used in MWNT growth processes on Si.

A digital lock-in upgrade of the motional Stark effect diagnostic on DIII-D.

The use of lock-in amplifiers for phase sensitive detection of motional Stark effect (MSE) diagnostic signals is of critical importance to real-time internal current profile measurements in tokamak plasmas. A digital lock-in (DLI) upgrade utilizing field programable gate array firmware has been installed on the MSE system of the DIII-D tokamak for the eventual replacement of largely obsolete analog units. While the new digital system has shown a small reduction in electronic noise over the analog, the main advantages are reduced cost, hardware simplicity, compact size, and phase tracking during plasma operations. DLI recovery of MSE polarization angles was accomplished through use of reference processing to produce only photoelastic modulator (PEM) second harmonic frequencies and electronic signal processing to maximize the fidelity of the recovered signal. A simplified discrete analytical solution was found that accurately describes the new DLI hardware. The DLI algorithm was found to cause a prohibitively large oscillating artifact atop the demodulated signal. The artifact was caused by the accumulator interval not containing an exact integer number of PEM multiplier periods. Successful MSE measurements require the minimization of this oscillating artifact amplitude. The analytical solution was used to select an appropriate accumulator interval that both reduces the artifact and maintains the greatest temporal resolution possible. Sample EFIT equilibria reconstructions and corresponding safety factor profiles showed very close agreement between the analog and digital lock-ins.

A comparison of human and machine-based predictions of successful weaning from mechanical ventilation.

PURPOSE: To evaluate the ability of an appropriately trained neural network to correctly interpret a set of weaning parameters to predict the liberation of a patient from mechanical ventilation, and to contrast these predictions with those of human experts restricted to the same limited set of physiologic data. METHODS: For each set of weaning parameters, a prediction was made by multiple realizations of a neural network and six expert volunteers. RESULTS: The percentage of correct predictions made by the neural network when the decision threshold was set to 0.5 (range 0-1) was 83.3 +/- 4.2 (mean +/- SD) and that for the experts was 83.3 +/- 4.7. Predictions by the network when the threshold was 0.5 had a sensitivity of 0.83 and a specificity of 0.84, compared with 0.90 and 0.77, respectively, for the experts. However, sensitivity and specificity comparable to those of the human experts could be obtained by adjusting the decision threshold of the network predictor so that only the most clearly ventilator-dependent patients would not be given a trial of extubation. CONCLUSION: When both are restricted to the same limited set of patient data, appropriately trained neural networks can be as effective as human experts in predicting whether weaning from mechanical ventilation will be successful.

Laparoscopic adrenalectomy. A new standard of care.

OBJECTIVE: The authors review their experience with laparoscopic adrenalectomy in patients with benign adrenal neoplasms. Efficacy, safety, and cost effectiveness of the procedure are examined. BACKGROUND: Laparoscopic adrenalectomy is replacing open adrenalectomy in some medical centers as the standard surgical approach for uncomplicated tumors. However, laparoscopic adrenalectomy often is considered more difficult and more expensive than traditional "open" surgery. METHODS: Perioperative and postoperative records as well as hospital charges from the first 19 patients undergoing laparoscopic unilateral adrenalectomies at the authors' medical institutions were examined and compared with 19 patients who underwent open unilateral adrenalectomies. RESULTS: None of the 19 patients undergoing unilateral laparoscopic adrenalectomy required conversion to open adrenalectomy. Mean operative times as well as total hospital charges were similar in those patients undergoing either laparoscopic or open adrenalectomy. However, the morbidity and postoperative length of hospital stay were significantly less in those patients undergoing laparoscopic adrenalectomy. CONCLUSIONS: Laparoscopic adrenalectomy can be performed safety and with the benefits associated with minimally invasive surgery. In addition, the procedure is cost effective. These factors suggest that laparoscopic adrenalectomy should be the preferential surgical technique for benign adrenal disease.

Treatment of soft-tissue sarcomas of the hand.

We studied the clinical features, radiographic and pathological findings, treatment, and results for twenty-three patients who had been managed for a soft-tissue sarcoma of the hand between 1982 and 1990. The ages of the patients ranged from sixteen to seventy-six years (median age, thirty-one years). The most common clinical finding was a small, painless soft-tissue mass. Twenty of the tumors were high-grade, and eighteen were less than five centimeters in diameter. The most common diagnosis was synovial sarcoma, which was identified in eight patients. Leiomyosarcoma, rhabdomyosarcoma, and malignant fibrous histiocytoma developed in three patients each; epithelioid sarcoma, in two patients; and angiosarcoma, liposarcoma, neuroectodermal tumor, and clear-cell sarcoma, in one patient each. Curative wide excision or amputation was attempted in twenty-two patients; the margins were positive for tumor cells in eight, and local recurrence was seen in nine. Of the twenty-three patients, fourteen had survived, without evidence of disease, after a median duration of follow-up of forty-nine months, and nine had died of disease. The median rate of survival did not differ significantly on the basis of the size or grade of the tumor or the use of adjuvant treatment. However, the rate of survival of the patients who had a soft-tissue sarcoma of the hand that was less than five centimeters in diameter was significantly lower (p = 0.0008) than that of 152 patients who had a similar tumor at another site in an extremity.(ABSTRACT TRUNCATED AT 250 WORDS)

Exposure of the mucosa of the gastroesophageal junction in patients with Mallory-Weiss tears.

A technique helpful in exposing the mucosal aspect of the gastroesophageal junction is described.

Cardiovascular stability with rapid intravenous infusion of ondansetron.

The acute cardiovascular effects of rapid iv administration of the antiemetic ondansetron, a selective serotonin (5-HT3) receptor antagonist were determined in a randomized, blinded, placebo-controlled study. Measurements of heart rate, blood pressure, oxygen saturation and respiratory rate were made preoperatively over a five-minute period which followed a two-minute infusion of the medication. Intraoperative and postoperative data were not collected. None of the variables recorded changed significantly during the infusion or in the observation period which followed. Within the limitations of this study, we detected no cardiovascular change in the five minutes between the end of the drug infusion and the induction of anaesthesia.

Prognostic indicators for survival after resection of pancreatic adenocarcinoma.

From October 1983 to October 1990, 799 patients with the diagnosis of pancreatic adenocarcinoma were admitted to Memorial Sloan-Kettering Cancer Center, and their records were entered into a prospective database. Curative resection was possible in 146 patients (18%), with a 30-day operative mortality of 3.4%. Median follow-up of survivors in the resection group was 28 months. Actuarial 5-year survival in patients who did not undergo resection was 0% (n = 653), compared with 24% in the patients who had resection (p < 0.00001). Of 52 patients available for 5-year follow-up, 10 (19%) were alive at 5 years. Tumors with lymph node involvement, poor histologic tumor differentiation, and tumor size greater than 2.5 cm were predictors of a significantly worse survival in both univariate and multivariate analysis. Other factors, including blood transfusion, blood loss, and operative time, had no significant effect on survival. The majority of patients with pancreatic adenocarcinoma have unresectable disease with a poor prognosis. For patients who undergo curative resection, their prognosis appears to be determined by the biology of the tumor rather than factors involved in the resection.

Oxygen radical-mediated DNA damage by redox-active Cr(III) complexes.

The mechanism of DNA damage induced by Cr(III) complexes is currently unknown even though it is considered to be the ultimate biologically active oxidation state of chromium. In this study, we have employed the Salmonella reversion assay to identify mutagenic Cr(III) complexes. Cyclic voltammetry was used to differentiate the redox kinetics between mutagenic and selected nonmutagenic Cr(III) species. Plasmid relaxation of supercoiled DNA was employed to show in vitro interactions with plasmid DNA and correlate the interactions with the electrochemical behavior and biological activity. The results of this study demonstrate that the mutagenic Cr(III) complexes identified in the Salmonella reversion assay display characteristics of reversibility and positive shifts of the Cr(III)/Cr(II) redox couple consistent with the ability of these Cr(III) complexes to serve as cyclical electron donors in a Fenton-like reaction. These same mutagenic complexes display an ability to relax supercoiled DNA in vitro, presumably by the induction of single-strand breaks. Nonmutagenic complexes were selected to test different ligands to determine how the ligand directs the activity of Cr(III) complexes. All nonmutagenic complexes tested thus far have shown classical irreversibility, more negative reduction potentials, and an inability to relax supercoiled plasmid DNA. These results suggest that the mechanism by which chromium complexes potentiate mutagenesis involves an oxygen radical as an active intermediate. These data also demonstrate the effect of associated ligands with regard to the ability of a metal to generate an active redox center.

Management of small soft-tissue sarcoma of the extremity in adults.

To determine the significance of small (< or = 5 cm in diameter) soft-tissue sarcoma of the extremity, 174 adult patients were identified from information that had been entered prospectively into a database of 1742 patients between July 1982 and December 1990. Median follow-up was 48 months. The majority of tumors were high grade (n = 114; 66%). Local recurrence (n = 17) was seen in patients with both high-grade (11%) and low-grade tumors (7%). Distant metastases were seen in 7% of high-grade tumors and in no low-grade tumors. The overall 5-year survival rate was 94% for all patients. Grade, depth, location, type of operation, and sex did not affect 5-year survival or local recurrence-free survival. Neither postoperative adjuvant chemotherapy nor radiation therapy resulted in superior 5-year survival or local recurrence-free survival when compared with no postoperative treatment. The prognosis of these lesions is favorable, and no additional prognostic factors were identified. Inclusion of these patients into adjuvant therapy trials examining survival is inappropriate.

Interaction of gut and liver in nitrogen metabolism during exercise.

The role of the gut and liver in nitrogen metabolism was studied during rest, 150 minutes of moderate-intensity treadmill exercise, and 90 minutes of recovery in 18 hour-fasted dogs (n = 6). Dogs underwent surgery 16 days before an experiment for implantation of catheters in a carotid artery and in the portal and hepatic veins, and Doppler flow cuffs on the hepatic artery and portal vein. Arterial glutamine, alanine, and alpha-amino nitrogen (AAN) levels decreased gradually with exercise (P less than .05), while arterial glutamate, NH3, and urea were unchanged. Net gut glutamine uptake was 1.3 +/- 0.5 mumol/kg.min at rest, and increased transiently to 2.5 +/- 0.3 mumol/kg.min at 60 minutes of exercise (P less than .05) as gut extraction increased. Net hepatic glutamine uptake was 0.6 +/- 0.4 mumol/kg.min at rest, and increased to 3.4 +/- 0.6 and 2.6 +/- 0.5 mumol/kg.min after 60 and 150 minutes of exercise (P less than .05) as hepatic extraction increased. Net gut glutamate and NH3 output both increased transiently with exercise (P less than .05). These increases were matched by parallel increments in the net hepatic uptakes of these compounds. Alanine output by the gut and uptake by the liver were unchanged with exercise. Net gut AAN output was -2.1 +/- 1.8 mumol/kg.min at rest (uptake occurred), and increased transiently to 11.2 +/- 3.5 mumol/kg.min after 30 minutes of exercise (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)