Admittance calculation of a slot in the shield of a multiconductortransmission line

The admittance calculation for a narrow slot in the conducting shield of a multiconductor transmission line (MTL) is presented. An approximate calculation is given for the admittance seen looking into a slot in the shield of a multiconductor transmission line when a uniform magnetic current is placed over the slot. The calculation presented is approximate in that only the transmission line mode is used in the calculation. All higher-order waveguide modes are neglected. This allows the magnetic current to be replaced by a point voltage source at the slot location. The admittance calculation then corresponds to calculating the driving point admittance of a point voltage source located in the shield of an MTL     

Structural, optical and electrical properties of undoped polycrystalline hematite thin films produced using filtered arc deposition

Thin films of α-Fe₂O₃ (hematite) were deposited using filtered arc deposition. The structural, optical and electrical properties of the films have been characterized. High-purity hematite films were produced, free from other iron oxide phases and impurities. The films exhibit preferred orientation, with the c-axis of the hexagonal structure aligned perpendicular to the substrate. The films have an upper uncertainty bound of the porosity of 15%, with a microindentation hardness of 17.5 ± 1 GPa and elastic modulus of 1235 ± 5 GPa. The indirect and direct band gap energies were found to be approximately 1.9 eV and 2.7 eV, respectively. The refractive index, and the extinction and absorption coefficients were determined from total reflectance and direct transmittance measurements. The thin films exhibit a high resistivity (≥ 10⁵ Ω cm) which indicates pure α-Fe₂O₃. An activation energy of 0.7 eV was calculated from an Arrhenius plot of the conductivity.     

Performance of a prototype surface collector for juvenile salmonids at Bonneville Dam's first powerhouse on the Columbia River,Oregon

During April–July 2000, we radio‐tagged and released juvenile Chinook salmon (Oncorhynchus tshawytscha) and steelhead (Oncorhynchus mykiss) to evaluate a prototype surface flow bypass at Bonneville Dam on the Columbia River. The mock bypass, called a prototype surface collector (PSC), had six vertical slot entrances that were each 6 m wide and 12 m deep. The PSC was retrofitted to the upstream face of Bonneville Dam's First Powerhouse. Our objectives were to: (1) assess species‐specific differences in movement patterns and behaviour of fish within 6 m of the face of the PSC, (2) estimate the efficiency and effectiveness of the PSC and (3) evaluate factors affecting the performance of the PSC. We found that 60–72% of the fish, depending on species, detected within 6 m of the PSC entered it. Of the fish that passed the First Powerhouse at turbines 1–6, 79–83% entered the PSC. Diel period was a significant contributor to PSC performance for all species, and day of year was a significant contributor to PSC performance for subyearling Chinook salmon. The PSC was twice as effective (%fish/%flow) as the spillway, passing 2.5:1 steelhead and subyearling Chinook salmon and 2.4:1 yearling Chinook salmon per unit of water. If fully implemented, the PSC would increase the percentage of fish that pass the First Powerhouse through non‐turbine routes from 65–77% (without the PSC) to 76–85% (with the PSC), depending on species. Published in 2008 by John Wiley & Sons, Ltd.     

Intra- and interlaboratory reproducibility of ultra performance liquid chromatography-time-of-flight mass spectrometry for urinary metabolic profiling

Liquid chromatography coupled to mass spectrometry (LC-MS) is a major platform in metabolic profiling but has not yet been comprehensively assessed as to its repeatability and reproducibility across multiple spectrometers and laboratories. Here we report results of a large interlaboratory reproducibility study of ultra performance (UP) LC-MS of human urine. A total of 14 stable isotope labeled standard compounds were spiked into a pooled human urine sample, which was subject to a 2- to 16-fold dilution series and run by UPLC coupled to time-of-flight MS at three different laboratories all using the same platform. In each lab, identical samples were run in two phases, separated by at least 1 week, to assess between-day reproducibility. Overall, platform reproducibility was good with median mass accuracies below 12 ppm, median retention time drifts of less than 0.73 s and coefficients of variation of intensity of less than 18% across laboratories and ionization modes. We found that the intensity response was highly linear within each run, with a median R(2) of 0.95 and 0.93 in positive and negative ionization modes. Between-day reproducibility was also high with a mean R(2) of 0.93 for a linear relationship between the intensities of ions recorded in the two phases across the laboratories and modes. Most importantly, between-lab reproducibility was excellent with median R(2) values of 0.96 and 0.98 for positive and negative ionization modes, respectively, across all pairs of laboratories. Interestingly, the three laboratories observed different amounts of adduct formation, but this did not appear to be related to reproducibility observed in each laboratory. These studies show that UPLC-MS is fit for the purpose of targeted urinary metabolite analysis but that care must be taken to optimize laboratory systems for quantitative detection due to variable adduct formation over many compound classes.     

Stage specificity, dose response, and doubling dose for mouse minisatellite germ-line mutation induced by acute radiation

Germ-line mutation induction at mouse minisatellite loci by acute irradiation with x-rays was studied at premeiotic and postmeiotic stages of spermatogenesis. An elevated paternal mutation rate was found after irradiation of premeiotic spermatogonia and stem cells, whereas the frequency of minisatellite mutation after postmeiotic irradiation of spermatids was similar to that in control litters. In contrast, paternal irradiation did not affect the maternal mutation rate. A linear dose-response curve for paternal mutation induced at premeiotic stages was found, with a doubling dose of 0.33 Gy, a value close to those obtained in mice after acute spermatogonia irradiation using other systems for mutation detection. High frequencies of spontaneous and induced mutations at minisatellite loci allow mutation induction to be evaluated at low doses of exposure in very small population samples, which currently makes minisatellite DNA the most powerful tool for monitoring radiation-induced germ-line mutation.     

Pharmacokinetics and antiretroviral activity of lamivudine alone or when coadministered with zidovudine in human immunodeficiency virus type 1-infected pregnant women and their offspring

The safety, pharmacokinetics, and antiretroviral activity of lamivudine alone and in combination with zidovudine was studied in pregnant women infected with human immunodeficiency virus type 1 (HIV-1) and their neonates. Women received the drugs orally from week 38 of pregnancy to 1 week after delivery. Neonate therapy began 12 h after delivery and continued for 1 week. Both treatment regimens were well-tolerated in women and newborns. Lamivudine and zidovudine pharmacokinetics in pregnant women were similar to those in nonpregnant adults. Lamivudine and zidovudine freely crossed the placenta and were secreted in breast milk. Neonatal lamivudine clearance was about half that in pediatric patients; zidovudine clearance was consistent with previous reports. HIV-1 RNA could be quantified in 17 of the 20 women. At the onset of labor/delivery, mean virus load had decreased by approximately 1.5 log10 copies/mL in both treatment cohorts. Although not definitive for HIV-1 infection status, all neonates had HIV-1 RNA levels below the limit of quantification at birth and at ages 1 and 2 weeks.     

Optical network packet error rate due to physical layer coding

A physical layer coding scheme is designed to make optimal use of the available physical link, providing functionality to higher components in the network stack. This paper presents results of an exploration of the errors observed when an optical gigabit Ethernet link is subject to attenuation. The results show that some data symbols suffer from a far higher probability of error than others. This effect is caused by an interaction between the physical layer and the 8B/10B block coding scheme. The authors illustrate how the application of a scrambler, performing data whitening, restores content-independent uniformity of packet loss. They also note the implications of their work for other (N, K) block-coded systems and discuss how this effect will manifest itself in a scrambler-based system. A conjecture is made that there is a need to build converged systems with the combinations of physical, data link, and network layers optimized to interact correctly. In the meantime, what will become increasingly necessary is both an identification of the potential for failure and the need to plan around it.     

Endovascular treatment of arteriovenous graft pseudoaneurysms,indications, complications,and outcomes: A systematic review

There are limited data regarding endovascular treatment of arteriovenous graft (AVG) pseudoaneurysms using stent grafts. We performed a comprehensive literature review on the use of stent grafts in the treatment of AVG pseudoaneurysms. We included 10 studies (121 patients). The mean AVG age was 3.1 years (95% confidence interval [CI]: 2.2–4) and pseudoaneurysm mean diameter was 34 mm (95% CI: 23–46). The majority (71%) of the pseudoaneurysms were located on the arterial limb of the AVG and 77% presented with venous anastomosis stenosis requiring angioplasty. The mean number of stents used to treat one lesion was 1.4 (95% CI: 1.3–1.5). The technical success rate of pseudoaneurysm isolation was 100% in all studies and 100% of patients received hemodialysis using the AVG after pseudoaneurysm treatment without the need for catheter placement. The primary patency rates for 1, 3, and 6 months were 81%, 73%, and 24%. Secondary patency was 80%, 77%, and 74% at 1, 3, and 6 months. Arteriovenous graft thrombosis occurred in 12% of patients. Arteriovenous graft infection developed in 35% of cases. Arteriovenous graft pseudoaneurysm treatment using stent grafts is effective in managing even large pseudoaneurysms and has acceptable primary and secondary patency rates. Graft infection was a relatively frequent complication.     

THE EFFECT OF HETEROGENEITY ON WOOD DRYING, PART II: EXPERIMENTAL RESULTS

Experimental measurements of drying rate, moisture distribution, surface moisture content, and temperature distribution are reported for softwood dried in the radial, tangential, and mixed (between radial and tangential) directions. The effects of both the heterogeneous and the anisotropic structure of wood are observed. The drying curves for tangential drying exhibit two distinct transition points - one when the surface reaches the fiber saturation point and one when the surface becomes completely dry. These transitions are not observed consistently for drying in the radial and mixed directions. For mixed drying, as a result of anisotropy, the drying rate is always higher at the side of the sample to which the growth rings point at die surface. Measurements of the surface mass transfer coefficient indicate that the theoretical value which is analogous to the convective heat transfer coefficient agrees well with that measured experimentally at both very high and very low values of the surface moisture content. At intermediate values of the moisture content the ratio of the experimental to the theoretical convective mass transfer coefficient can be as low as 0.20. The model discussed in Part I predicts results that are in good qualitative agreement with the experimental results presented in this paper.