Comparison of open and thoracoscopic bilateral volume reduction surgery: complications analysis

BACKGROUND: The effectiveness of lung volume reduction for the treatment of patients with emphysema is well established, but data about the surgical approach, the postoperative management, and complications are limited. We report a comparison of patients undergoing bilateral lung volume reduction (BLVRS) via median sternotomy and thoracoscopic techniques with emphasis on hospital course and complications. METHODS: All patients undergoing BLVRS at Hospital of University of Pennsylvania were analyzed for mortality and morbidity, using a combination of prospective data analysis and retrospective chart review. RESULTS: Patients undergoing BLVRS via median sternotomy were older than those undergoing video-assisted thoracoscopic surgery (VATS) procedures (63.9+/-6.89 vs 59.3+/-9.4 years, p = 0.005). Operating time was longer for the VATS procedure (147 versus 129 minutes, p = 0.006) while estimated blood less was greater for median sternotomy (209 versus 82 L, p = 0.0000017). Significant differences were found in intensive care unit stay, days intubated, life-threatening complications, respiratory complications, requirement for tracheostomy, and death that favored VATS BLVRS. When only later cohorts of patients were compared, more life-threatening complications and deaths were found in patients undergoing BLVRS by median sternotomy. There were no differences between early and late median sternotomy BLVRS patients. Twenty-six percent of the lethal complications in median sternotomy BLVRS patients were bowel perforations, equally divided between duodenal ulcers and colons. CONCLUSIONS: Managing patients after BLVRS remains complex. Bilateral video-assisted volume reduction offers equivalent functional outcome with potentially decreased morbidity and mortality. Gastrointestinal perforations can complicate the management of these patients.     

Impurity effects on the nucleation and growth of primary Al3(Sc,Zr) phase in Al alloys

Impurity effects on the nucleation and growth of primary Al₃(Sc,Zr) phase have been investigated in high purity Al alloys and commercial purity Al alloys, respectively. In the case of high purity Al alloys, primary Al₃(Sc,Zr) phases were found to be pushed to grain boundaries ahead of the solidification front. Such type of primary Al₃(Sc,Zr) phase did not contribute to the heterogeneous nucleation, and thereby the grain refinement of Al alloys. In the case of commercial purity Al alloys, the presence of Fe, Si, Cu, Mg, Ti, and other impurities significantly enhanced the heterogeneous nucleation of primary Al₃(Sc,Zr) phase. Most primary Al₃(Sc,Zr) phases were found to be located within the α-Al matrix, and kept an identical orientation relationship with the α-Al matrix. Furthermore, the presence of the impurities also changed the growth mode on the primary Al₃(Sc,Zr) phase. In the case of commercial purity Al alloys, a peritectic to eutectic reaction was induced due to the presence of the impurities. A layered growth was observed leading to a narrow particle size distribution. In contrast, in the case of high purity Al alloys, a featureless structure was observed. This investigation demonstrates that impurities and their concentrations are important factors affecting the nucleation and growth of primary Al₃(Sc,Zr) phases, and thereby for the successful grain refinement in Al-based alloys.     

Partitioning of [C]PCB between water and particulates with various organic contents

The use of [¹⁴C]PCB was an effective technique for evaluating the partitioning of PCB between water and particulates. The sorption of [¹⁴C]PCB to clay and/or organic particulates and its subsequent degree of retention on the particles in clean medium was directly related to the particle organic content. Concentration factors (PCB on particles/PCB in water) ranged from 1.1 × 10⁴ for 100% inorganic illite clay to 4.9 × 10⁴ for 100% organic matter.     

Separation of the methyl esters of oleic,linoleic, and linolenic acids by column chromatography using cation exchange resin containing silver ion

By taking advantage of the tendency of silver ion to form complexes with unsaturated compounds, the methyl esters of oleic, linoleic, and linolenic acids have been cleanly separated in good yield by column chromatography. The silver ion was supported by means of a cation exchange resin; no silver was ever eluted from the column. Aqueous methanol, pure methanol, and ethanol saturated with butene-1 were employed as solvents.     

Sorption of polychlorinated biphenyls (PCB) to clay particulates and effects of desorption on phytoplankton

The sorption of polychlorinated biphenyls (PCB) on illite and chlorite, two minerals of defined composition, was investigated. Illite particles adsorbed higher [¹⁴C]PCB (Aroclor 1254) concentrations than did chlorite particles, with equilibrium concentration factors between particles and water being 1.4 × 10⁴ for illite and 1.0 × 10⁴ for chlorite. Desorbed PCB inhibited photosynthesis and reduced chlorophyll-a content of natural phytoplankton assemblages within dialysis membrane bags suspended in the water of a tidal marsh. There was no significant difference in effects on the phytoplankton of PCB desorbed from the two minerals. The rate of [¹⁴C]PCB desorption was dependent on the initial concentration on the clay particles. The rate of [¹⁴C]PCB loss from bags with particles was slower than that from bags without particles.     

Evaluation of a suture electrode for direct bladder stimulation in a lower motor neuron lesioned animal model.

The purpose of this study was to evaluate a "suture" type electrode for direct bladder stimulation in an animal model of a lower motor neuron lesion. During an initial surgery, five male cats were instrumented under anesthesia using multistranded, 316 LVM, stainless-steel, wire electrodes implanted on the bladder wall serosa above the trigone area. Electrodes were constructed with a needle attached to the end that was removed after suturing the electrode in place. Additional instrumentation included urinary bladder catheters (tubes) for pressure recording and filling, and hook type electrodes for leg and pelvic floor electromyography recording. Chronic bladder filling and stimulation studies were conducted in tethered animals three to four weeks following surgery. To test these electrodes in a spinal cord injury model, a lower motor neuron lesion was performed including the sacral cord and complete nerve roots at L6 and below. These animals were evaluated during weeks 3 and 10 after injury. Direct bladder stimulation induced active contractions and voiding both before and after spinal cord injury. Effective stimulation parameters consisted of 40 pulses per s, 300 micros to 1 ms pulse duration, a stimulation period from 3 to 4 s, and a stimulation current from 10 to 40 mA. Fluoroscopy revealed an open membranous urethra during stimulation and following stimulation. A small diameter penile urethra was observed to limit flow. Postmortem evaluation of the suture electrode revealed no abnormalities such as corrosion, migration into the bladder lumen or displacement. These findings indicate that suture electrodes are suitable and effective for short-term implantation in the lower motor neuron animal model.     

Electron optical property of a charged foil,observed with a transmitted electron detector device in an SEM

Experimental evidence is presented for the electron optical behaviour of a charged foil area, using the transmitted electron detection device of the scanning electron microscope JSM 50 A (JEOL). The primary electron beam scanning a thin pioloform foil on the one hand produces a charged foil region which on the other hand acts as an electron lens to the primary and scattered electrons. Scanning electron microscopical investigations of air particulates in the submicron size range can be eased by using a transmitted electron detection device both of the bright and dark field operation mode. The image contrast thus may be improved by orders of magnitude, also allowing on line operation of an image analysis system. Using a special preparation technique, depositing the particles on a thin supporting foil which is also used for LAMMA analysis – Wieser et al. 1980, the x-ray spectra of single particles provided by an energy dispersive x-ray spectrometer may be quantitatively interpreted on the basis of the peak-to-background method (Statham and Pawley 1978, Small et al. 1979). Figure 1 shows a schematic of the transmission detector device of the JSM 50 A when operated in the dark field mode. Geometrical dimensions and apertures also are given in Fig. 1. The dark field diaphragm (DFD) on the optical axis of the microscope blocks all electrons (primary electrons and scattered electrons) within an angle of about 10^?2 rad from contributing to the video signal. As long as magnifications above about 350 × are used the primary electron beam hits the DFD thus yielding a transmission scanning electron micrograph in dark field mode. Below this limit or above the corresponding maximal scanning angle (about 7 × 10^?3 rad) of the primary electron beam the rim of the DFD becomes visible in the displayed image as shown in Fig. 2a. At the same magnification Figure 2b shows the sharpened contours of the DFD as obtained by focussing the primary electron beam to the plane of the DFD by lowering the objective lens excitation. By means of the thin bar attached to the DFD (left hand upper corner of Fig. 2b) the DFD may be centered to the optical axis or exchanged to the bright field aperture. Looking to the circular center of Fig. 2a, we recognize the black grid bars and a few black particles whereas the supporting foil looks bright. No video signal can be obtained, because both the grid bars, and to a lesser extent the particles, are not transparent to the primary electrons of 15 keV energy. On the other hand all electrons scattered by the thin foil to an angle of more than 10^?2 rad are seen by the scintillator and hence accumulate a measurable video signal: This is also favoured by the large solid angle outside the DFD, which is about 30 times the solid angle of the DFD itself.     

Lateral beam stability of a computer assisted scanning electron microscope / x-ray microanalysis system

Digital beam control by an image analyzer has opened up new dimensions for scanning electron microscopy and x-ray microanalysis, particularly if the feature density in the sample is high. Prior to its application to aerodynamically classified particles in the micron and submicron size range, the performance of a given system was tested by means of a special object, consisting of a pattern of micron sized holes in a metallic foil. The lateral position of the electron beam was registrated using the centre of gravity values (x- and y-axis) as obtained by consecutively analyzing transmission scanning electron micrographs (bright field mode) of the special object at constant intervals. A major drift source (time dependent electrical interference field) could be detected and eliminated, thus reducing shift speeds exceeding 3 μm/h to values below 0.5 μm/h if thermally induced effects both in the electron source and related electronic circuitry were allowed to become nearly saturated. It is shown that remanence effects in the scanning coils resulting from magnification changes can produce severe sideways jumps in the beam position that must be borne in mind if unattended operation of the system is intended on features of corresponding size.     

Countering unauthorized code execution on commodity kernels: A survey of common interfaces allowing kernel code modification

Motivated by the goal of hardening operating system kernels against rootkits and related malware, we survey the common interfaces and methods which can be used to modify (either legitimately or maliciously) the kernel which is run on a commodity desktop computer. We also survey how these interfaces can be restricted or disabled. While we concentrate mainly on Linux, many of the methods for modifying kernel code also exist on other operating systems, some of which are discussed.