The Impacts of Atlantic Salmon Stocking on Rainbow Trout in Barnum House Creek,Lake Ontario

We compared the impacts of stocking age-0 Atlantic salmon (Salmo salar) at high and low densities, and no stocking on abundance and growth of age-0 rainbow trout (Oncorhyncus mykiss) in Barnum House Creek, Ontario during 1993 to 2005. A similar stream, Shelter Valley Creek, was chosen as an appropriate reference stream where age-0 Atlantic salmon were not stocked. The catches of age-0 rainbow trout in Barnum House and the reference stream were highly correlated (r = 0.96) during years when no stocking occurred; however, this relationship did not persist in years when Atlantic salmon were stocked. The catch of age-0 rainbow trout in Barnum House Creek was significantly lower under both high (P = 0.00026) and low (P = 0.011) density Atlantic salmon stocking treatments compared with the no stocking treatment. The catches of age-0 rainbow trout and age-0 Atlantic salmon were negatively correlated in Barnum House Creek (r = −0.63). The length of age-0 rainbow trout in Barnum House Creek was depressed significantly (P = 0.004), under the high intensity Atlantic salmon stocking treatment, but not under the low intensity treatment (P = 0.20). In contrast, the length of age-0 rainbow trout in Shelter Valley Creek was unchanged over the same period. Restoration stocking of Atlantic salmon in Lake Ontario tributaries may impact rainbow trout abundance and growth.     

Crystallographic and physical properties of new ternary R2T3X9 (R=La, Ce, U, T=Rh, Ir, X=Al, Ga) compounds

Ternary compounds with the stoichiometry R₂T₃X₉ (R=La, Ce, U, T=Rh, Ir, X=Al, Ga) were synthesized for the first time and were found to crystallize in the orthorhombic Y₂Co₃Ga₉-type structure. Preliminary measurements of the resistivity, the susceptibility, the specific heat, and the Seebeck coefficient revealed a rather unconventional behavior for the Ce-compounds, which exhibit characteristics of both intermediate valent and of heavy fermion compounds. The U counterparts were found to order antiferromagnetically at temperatures below 40 K.     

Electrocrystallization of nanocrystallite calcium phosphate coatings on titanium substrate at different current densities

Calcium phosphates were electrocrystallized on titanium substrate by electrochemical deposition technique, in which the electrolyte was 0.167 M CaCl₂ and 0.1 M NH₄H₂PO₄. Different current densities (0.375, 1.5, 3, 6 mA/cm²) were applied. The pH of the solution after mixing of equal volumes was 4.6. The surface morphology, chemical composition and phase identification of the coatings were investigated by scanning electron microscopy associated with an energy dispersive spectrometer (SEM-EDXS) and X-ray diffractometry (XRD). Effects of the current density on the morphology and the structure of the coating were also discussed.The results showed that at all current densities tested, the coating is brushite (dicalcium phosphate dihydrate CaHPO₄ · 2H₂O). Furthermore, the results showed that coating thickness and weight gain are increased and the morphology changed with increasing deposition current density (from 0.375 to 6 mA/cm²). On contrary, thickness and weight gain are decreased with sodium hydroxide treatment. NaOH treatment converts brushite of Ca/P ratio 1:1 to hydroxyapatite of Ca/P ratio of 1.667. So, chemical analysis of the solution shows soluble P₂O₅ content. Coating thickness at 6 mA/cm² was about 20 and 30 µm with and without treatment, respectively. It decreased to about 9.5 and 12 µm at 0.375 mA/cm² current density, with and without treatment, respectively. However, the formed phase is not changed with increasing current density. In addition, it is found that, even at high current density (6 mA/cm²), no hydroxyapatite was directly electrocrystallized due to low corresponding potential (less than 5 V) and low corresponding voltage (468 mV).     

Signal processing in an optical polarization diversity receiver for560-Mbit/s ASK heterodyne detection

Polarization diversity is an alternative technique for coherent receivers to prevent loss to signal due to variations in the states of polarization (SOP) of the received signal field. It is shown experimentally and theoretically that there is no significant power penalty difference between a receiver with optimally adjusted gains and receivers with linear envelope detection and square-law detection. Experimentally, two amplitude-shift keying (ASK) heterodyne polarization diversity receivers with envelope detectors were demonstrated at 560 Mb/s, one using linear rectifiers, the other using square-law rectifiers. In both cases, the receiver sensitivity of -35 dBm at BER=10 ^-9 was degraded by less than 1 dB as the received signal SOP was varied, in agreement with theory     

Semiconductor laser optical amplifiers for multichannel coherentoptical transmission

The application of semiconductor laser optical amplifiers in multichannel coherent optical transmission systems is investigated. The amplifiers considered (λ=1.3 μm) exhibit a gain of 24 dB at a grain ripple <2 dB and a 3-dB bandwidth of about 4000 GHz. The characteristics of these amplifiers and transmission experiments with these amplifiers are described. The investigations concern noise accumulation in an amplifier chain, generation of echoes due to backward gain in cascaded amplifiers, crosstalk in multichannel transmission, and the effect of gain saturation due to spontaneous emission. A good fit is shown between the advantages of multichannel coherent optical transmission systems and the properties of semiconductor laser optical amplifiers, which are very promising for future long-haul optical transmission systems     

Simultaneous degradation of disinfection byproducts and earthy-musty odorants by the UV/H2O2 advanced oxidation process

Advanced treatment technologies that control multiple contaminants are beneficial to drinking water treatment. This research applied UV/H₂O₂ for the simultaneous degradation of geosmin, 2-methylisoborneol, four trihalomethanes and six haloacetic acids. Experiments were conducted in de-ionized water at 24 ± 1.0 °C with ng/L amounts of odorants and μg/L amounts of disinfection byproducts. UV was applied with and without 6 mg/L H₂O_2. The results demonstrated that brominated trihalomethanes and brominated haloacetic acids were degraded to a greater extent than geosmin and 2-methylisoborneol. Tribromomethane and dibromochloromethane were degraded by 99% and 80% respectively at the UV dose of 1200 mJ/cm² with 6 mg/L H₂O₂, whereas 90% of the geosmin and 60% of the 2-methylisoborneol were removed. Tribromoacetic acid and dibromoacetic acid were degraded by 99% and 80% respectively under the same conditions. Concentrations of trichloromethane and chlorinated haloacetic acids were not substantially reduced under these conditions and were not effectively removed at doses designed to remove geosmin and 2-methylisoborneol. Brominated compounds were degraded primarily by direct photolysis and cleavage of the C-Br bond with pseudo first order rate constants ranging from 10⁻³ to 10⁻² s⁻¹. Geosmin and 2-methylisoborneol were primarily degraded by reaction with hydroxyl radical with direct photolysis as a minor factor. Perchlorinated disinfection byproducts were degraded by reaction with hydroxyl radicals. These results indicate that the UV/H₂O₂ can be applied to effectively control both odorants and brominated disinfection byproducts.     

High-frequency modeling of current sensors [of IGBT VSI]

Reflected-wave transient voltages that result from fast insulated gate bipolar transistor voltage-source inverters have received considerable investigation. Modeling, simulation and attenuation of these transients require sophisticated motor and cable models. Most drive suppliers now provide combinations of passive and active solutions to mitigate the adverse effects of overvoltage stress, however, the costs of the passive solutions often exceed the cost of the drive. Another aspect of low-risetime devices, not examined to the extent of the overvoltage problem, is the resulting current from traveling waves. Current sensor fidelity limits the ability of modern drives to detect peak current and can result in current feedback distortion. This paper presents recent research into the response, modeling and construction of Hall-effect current sensors. Models for Hall-effect current sensors are introduced and compared. Experimental and simulation results demonstrate the complexity of the common current sensors employed in modern adjustable-speed drives. A comparison of the sensor response and the model's prediction demonstrates the difficulty associated with accurate current detection. Finally, the paper presents design guidelines to reduce the corrupting influence of high-frequency differential and common-mode currents