Value of intraoperative cholangiography in laparoscopic cholecystectomy

By introduction of laparoscopic cholecystectomy, an increase of accidental common bile duct injuries up to 1.2% has been reported. In the present study of 325 cholecystectomies we evaluated whether mandatory intraoperative cholangiography (IOC) can reduce the rate of accidental bile duct injuries or, at least, identify them early in order to make an adequate repair possible. In addition 163 patients underwent preoperative intravenous cholangiography (IVC). Both imaging techniques were compared with regard to their sensitivity in the detection of anatomic variations and stones of the extrahepatic bile duct system. Our results demonstrated a great advantage of the IOC. The IOC was feasible in 98.1% of the cases and presented a complete depiction of the extrahepatic bile duct system in 99.3%. IVCs showed the biliary system in 91.4% of the cases but without visualization of the cystic duct in 51.5% and the hepatic confluence in 16%. Anatomic variations of the bile duct system which consecutively influenced the operative management were found in additional 27.6% exclusively by IOC. 71.4% of bile duct stones were not detected by IVC. The intraoperative time consumption of IOC was unimportant. The x-ray-load was clearly lower by a factor of 3.5. There was no complication after IOC. In comparison, 6.1% of patients demonstrated an anaphylactic reaction by IVC. One common duct injury (0.3%) was detected intraoperatively by IOC and at the same operation treated without postoperative complications. In conclusion, we recommend an IOC in addition to a thorough preoperative ultrasound-examination. By this technique intraoperatively identified stones of the common bile duct can be sufficiently treated by postoperative endoscopic extraction and anatomic variations of the bile duct system will be visualized and therefore accidental injuries will be avoided.     

Shallow Donors and Compensation in Homoepitaxial ZnO Thin Films

Nominally undoped homoepitaxial ZnO thin films grown with pulsed-laser deposition at various oxygen partial pressures (3 × 10⁻⁴–0.1 mbar) were investigated with respect to shallow donors and compensation. From x-ray diffraction and photoluminescence studies, a correlation of the oxygen partial pressure and the strain in the samples was found. Capacitance–voltage and thermal admittance measurements, using PtO _x -Schottky diodes, revealed a higher compensation for increasing oxygen partial pressure. A shallow donor level with a thermal activation energy of ∼40 meV was observed by thermal admittance spectroscopy. This defect level was attributed to the I_3a transition observed in photoluminescence and commonly assigned to interstitial zinc.     

Cadmium contents in cereal samples in the past--a comparison with the present

Samples of wheat, rye and barley from previous harvests, some of them dating back even to the past century and placed at the authors' disposal by a number of seed growers and governmental research institutions, were examined for their cadmium content by AAS or ICP-AES. Although no statistically valid data could be obtained owing to the low number of samples, it should nevertheless be stressed that the cadmium content found in cereal samples from harvests of the past were within the range of present-day wheat samples. Thus, the variation in wheat samples from former harvests was 20-100 micrograms/kg which is coincident with an average cadmium content of 50-60 micrograms/kg measured in 2000 what samples from the harvests of the last 10 years as determined in a special survey by the Federal Ministry of Food, Agriculture and Forestry. Comparison of the results for cereals samples from harvests of the past and the samples of the survey conducted by the Ministry does not indicate a trend towards a continuously rising cadmium contents of bread cereals.     

Accuracy issues for parameter estimation of field orientedinduction machine drives

This paper attempts to resolve a major area of concern for self-commissioning of induction machine drives: easily implemented methods capable of accurate parameter estimation. Most of the self-commissioning techniques are based on some form of statistical analysis. Classical statistical techniques such as ARMA (z-transform) methods using sampled line voltages, phase currents, and rotor velocity can easily produce large (2× or more) parameter errors. The first principles causing the errors and the methods of reducing those effects to tolerable levels are the focus of this paper     

Growth Dynamics of Cladophora Glomerata in Western Lake Erie in Relation to Some Environmental Factors

Cladophora was monitored at two sites in western Lake Erie during 1979 and 1980 as part of a lake-wide Lake Erie Cladophora Surveillance Program. Two distinctive zones within the littoral region were colonized by the alga, the eulittoral (splash zone) and infralittoral (defined in the present study as the 0.5–4 m depth zone). Cladophora of the eulittoral zone became established in May and remained present until late fall. The infralittoral zone Cladophora exhibited a bimodal growth pattern related to the seasonal temperature regime, with growth occurring from April to July and again from September to November. The infralittoral zone supported the largest share of biomass, which resulted in nuisance accumulations upon the beaches in the island region. Peak biomass was observed from mid-June to early July, obtaining maximum values of 102 gDW/m² and 214 gDW/m² for the 1979 and 1980 seasons, respectively. The depth to which Cladophora colonized was limited by light availability; maximum depth of growth occurred between 2 and 4 m in western Lake Erie due to the turbid nature of the basin. Phosphorus and nitrogen were not limiting to Cladophora growth in western Lake Erie; tissue nutrients remained above the critical levels defined by Gerloffand Fitzgerald (1976) throughout the season.     

Geometrical resonance effects in HTSC break junctions

A periodic structure has been observed in the tunneling characteristics of HTSC break junctions. This structure is explained in terms of the electron-hole interference effect in the surface layer, which causes the formation of bound states in the normal regions N of the SNINS-type junctions. Good qualitative agreement has been found between experimental data and the predictions of the Arnolds proximity model. Several parameters of the SNINS-type structures have been derived from studies of Fiske resonances in HTSC Josephson break junctions in weak magnetic fields.     

Image Sequence Interpolation Using Optimal Control

The problem of finding an interpolating image between two given images in an image sequence is considered. The problem is formulated as an optimal control problem governed by a transport equation, i.e. we aim at finding a flow field which transports the first image as close as possible to the second image. This approach bears similarities with the Horn and Schunck method for optical flow calculation but in fact the model is quite different. The images are modeled in the space of functions of bounded variation and an analysis of solutions of transport equations in this space is included. Moreover, the existence of optimal controls is proven and necessary conditions are derived. Finally, two algorithms are given and numerical results are compared with existing methods. The new method is competitive with state-of-the-art methods and even outperforms several existing methods.     

Difurfuryl diisocyanates: New adhesives derived from renewable resources

The syntheses of difurfuryl diisocyanates [e.g., ethylidenebis (2,5-furandiylmethylene) diisocyanate (EDFI)] have been reported in the literature. Difurfuryl diisocyanates are structurally similar to diphenylmethane diisocyanate (MDI), which has proven to be an excellent adhesive for bonding wood composites. The MDI regin is synthesized from petroleum-derived chemicals; the EDFI resin is synthesized from biomass-derived chemicals. In this study, the mechanical properties of aspen flakeboards bonded with MDI and EDFI are compared. In general, results show that the strength properties of flakeboards bonded with MDI are only marginally better than those bonded with EDFI. Because EDFI is more viscous than is MDI less than optimum atomization of the EDFI resin during spraying of the flakes is believed to be largely responsible for the differences in strength property values. The dry internal bond strength values of flakeboards bonded with MDI (1.33 MPa; 193 lb/in.²) at 3% resin content are significantly greater than the 0.41 MPa (60 lb/in.²) required by the American National Standards Institute (ANSI/A208.1) for type-2 medium-density particleboard. © 1993 John Wiley & Sons, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.