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  • 1
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on the observation of ultrafast (〈1 ps) recovery of all-optical modulation based on below band gap, optically induced excess absorption using pump pulse energies of less than 4 pJ. At higher pump pulse energies, the hot carriers produced by two-photon absorption significantly reduce the recovery rate. The increase in absorption recovery times at the higher densities of hot carriers is consistent with a contribution to the nonlinear absorption change from hot electron assisted absorption. The measured hot electron assisted absorption cross section of 2×10−20 m2 is in good agreement with the theoretical value.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The refractive nonlinearities due to bandfilling and the plasma effect in a multiquantum well buried heterostructure semiconductor waveguide under reverse bias are probed using self-phase modulation techniques. Modeling of the self-phase modulation has allowed the magnitude of the phase modulation and nonlinearity recovery time constant to be extracted. π radians phase shift has been obtained for a coupled pulse energy of 32 pJ. The nonlinearity recovery time constant is 18±3 ps for an applied field of 34 MV m−1, limited by thermionic emission from the quantum wells. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 1610-1612 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report measurements of quasi-cw optical bistability in an InGaAs/InP multiple quantum well waveguide Fabry–Perot cavity at 1.47 μm wavelength. This operating wavelength is detuned from the band-edge resonance by 0.07 μm, where an enhanced free-carrier contribution to the nonlinear refractive index due to 2D confinement of carriers in the quantum wells accounts for the large index variations. The effect of any thermally induced nonlinear response is negligible.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Aquaculture research 22 (1991), S. 0 
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. Mark-recapture experiments using Carlin tags on migrating wild smolts in the River Bush indicated that 16·4% were not recovered under total trapping conditions. The experimental procedure was also found to delay the migration of the smolts by varying amounts. The implications for the use of this technique as a means of assessing both smott run sizes in partially trapped rivers and smolt migration speeds are discussed.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1520-5002
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The efficacy and safety of calcipotriol solution in the treatment of scalp psoriasis was compared with placebo (vehicle solution), in a multicentre double-blind, randomized, parallel-group study of 49 adult patients. Calcipotriol solution (50 μg/ml), or placebo, was applied twice daily over a 4-week period. At the end of the study period 60% of patients on calcipotriol showed clearance or marked improvement of their psoriasis compared with 17% on placebo. Overall assessment of treatment response showed that calcipotriol was superior to placebo in both investigator (P〈0.001;95% confidence interval for difference 19.0–67.6) and patient (P〈0.001; 95% confidence interval for difference 18.3–68.0) assessments. Total sign score for psoriasis (i.e. the sum of the scores for redness, thickness and scaliness) decreased by 48.9% in the calcipotriol group, and by 18.6% in the placebo group (P =0.005). Calcipotriol was significantly superior to placebo in reducing redness, thickness, scaliness and extent of psoriasis, and in the patients’assessment in reducing scalp flaking and itching.No statistically significant changes in blood biochemistry were detected during the study, and the solution was generally well tolerated.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 45 (1994), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A semi-quantitative electrofishing technique is described, which has applications for assessing distribution and densities of 0+ salmonids in streams. Linear regressions of logarithmically-transformed data satisfactorily described the relationship between numbers of 0+ Atlantic salmon (Salmo salar L.) and 0+ brown trout (Salmo trutta L.) captured in a standard 5 min fishing and quantitative population estimates obtained using a commonly used method. Applications of the semi-quantitative technique to management are discussed and a categorization system proposed.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1351
    Keywords: Electric fish ; Pacemaker ; GABA ; Glutamate ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The medullary pacemaker nucleus of Hypopomus triggers each electric organ discharge (EOD) by a single command pulse. It consists of electrotonically coupled ‘pacemaker’ cells, which generate the rhythm, and ‘relay’ cells, which follow the pacemaker cells and excite the spinal motoneurons of the electric organ. The pacemaker cells receive two inputs from the complex of the diencephalic prepacemaker nucleus (PPn), a GABA-ergic inhibition and a glutamatergic excitation. Relay cells, on the other hand, receive two glutamatergic inputs, one from a subnucleus of the PPn, the PPn-C, and a second from the sublemniscal prepacemaker nucleus (SPPn). We have labelled afferents to the pacemaker nucleus by injecting HRP to specific sites of the prepacemaker complex. By using immunogold-labelled antibodies and en-grid staining techniques, we demonstrated GABA and glutamate immunoreactivity in labelled synaptic profiles of ultra-thin sections of the pacemaker nucleus. The two types of synapses were interspersed on the surfaces of pacemaker cells, with GABA-immunoreactive synapses apparently representing the GABA-mediated input of the ‘PPn-I’, an inhibitory subdivision of the PPn, and glutamate-immunoreactive synapses representing the input of the ‘PPn-G’, an excitatory subdivision of the PPn. Only glutamate-immunoreactive synapses were found on relay cells.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Archives of environmental contamination and toxicology 27 (1994), S. 311-317 
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Methylcyclopentadienyl manganese tricarbonyl (MMT) is an organic derivative of manganese (Mn) used in unleaded gasoline in Canada since 1977. It has been suggested that the production of Mn3O4 resulting from the combustion of MMT may become one of the principal sources of manganese contamination in the urban environment. This research evaluates the feral pigeon (Columba livia) as a monitor of Mn contamination in rural (Lachute) and urban (Montreal) environments. Atmospheric Mn concentrations were measured over a 6-month period in the rural and urban areas. Twenty pigeons were captured in each area and the Mn concentrations of several tissues (liver, kidney, lung, pancreas, intestine, brain, down feathers, feces, whole blood, and blood serum) were measured by neutron activation. Biochemical profiles of the blood samples (total protein, aspartate aminotransferase, hematocrit, glucose, and uric acid) were also measured. Air particulate data showed significantly higher Mn levels (p〈0.05) in the urban area (0.036 μg/m3) relative to the rural area (0.026 μg/m3). Mn concentrations were similar (P〉0.05) in the two groups of pigeons for all the tissues except liver (Lachute=2.42 ppm; Montreal=3.13 ppm) and feces (Lachute=32.2 ppm; Montreal=46.8 ppm); the urban pigeons had about 35% more Mn than the rural pigeons. Aspartate aminotransferase (AST) was also significantly different in the two groups. These results show the importance of the entero-hepatic cycle in the homeostasis of Mn in blood and other tissues. Since the excess of Mn in the feces and liver of the urban pigeons relative to the rural pigeons was similar to the excess Mn in urban air over rural air, pigeon feces and liver appear to be good biomarkers of Mn contamination. Although it is premature to associate this excess Mn with the combustion of MMT, these results nevertheless lead us to consider the pigeon as an interesting indicator of the potential risk to the ecosystem and to human health.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 44 (1993), S. 51-55 
    ISSN: 1432-1041
    Keywords: Cigarette smoking ; Cimetidine ; nicotine regulation ; nicotine elimination ; nicotine kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The efficacy of cimetidine as a treatment that could reduce smoking in heavily dependent smokers has been determined. In a randomised, double-blind, double-crossover experiment, 43 heavy smokers were divided into two groups, one receiving cimetidine 400 mg orally three times a day, and the other receiving placebo for two weeks followed by the alternative treatment (placebo or cimetidine). No significant difference in the mean alveolar carbon monoxide, nicotine or cotinine levels was found between the two treatment groups compared to baseline. Since the alveolar carbon monoxide level reflects the intensity of smoking behaviour, the results suggest that no change in smoking behaviour occurred in the subjects. Contrary to our previous findings that cimetidine decreased the total body clearance of nicotine by 30% in a population of non-smokers, in the heavily dependent smokers, cimetidine did not appear to alter nicotine elimination. One possible explanation for the discrepancy is that tobacco smoking is known to induce nicotine metabolism and the induction might have offset any effect of cimetidine on nicotine elimination. Cimetidine does not appear to be a useful treatment leading to a reduction or cessation of cigarette smoking.
    Type of Medium: Electronic Resource
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