Showing papers by "Government of Canada published in 1987"

Prediction of biological acid neutralization in acid-sensitive lakes

Abstract: Sulfate and nitrate removal, and the resulting sulfuric and nitric acid neutralization within acid-sensitive lakes, were predicted from a simple model requiring knowledge only of water residence time, mean depth, and average mass transfer coefficients for nitrate and sulfate removal. The model applies to lakes with oxic hypolimnia which are typical of acid-sensitive lakes. Average mass transfer coefficients for sulfate and nitrate were obtained by two independent methods which agreed well with each other. A model such as this is necessary for predicting the rates at which different lakes acidify and recover from acidification, and explains why lakes with short water residence times are especially susceptible to acidification.

Extreme olfactory sensitivity of mature and gonadally-regressed goldfish to a potent steroidal pheromone, 17α,20β-dihydroxy-4-pregnen-3-one

Abstract: 1. Electrical responses (electro-olfactogram; EOG) were obtained from the olfactory epithelium of goldfish exposed to a variety of sex steroids thought to function as pheromones, severall-amino acids, and a bile acid. Responses of male and female goldfish with both mature and regressed gonads were compared. 2. 17α,20β-dihydroxy-4-pregnen-3-one (17,20P) and progesterone were potent odorants. 17,20P had a detection threshold of 10−13M and at a concentration of 10−8M evoked an EOG response two to three times that of 10−5Ml-serine. Progesterone was less stimulatory than 17,20P. This finding corroborates recent endocrinological and behavioral studies (Stacey and Sorensen 1986; Dulka et al. 1987) which indicate that 17,20P is a potent pheromone in mature male goldfish. 3. Preliminary cross-adaptation experiments suggest that 17,20P is detected by receptor site(s) differing from those which detect bile acids andl-amino acids. 4. The goldfish olfactory epithelium did not respond to etiocholanolone glucuronide, 17β-estradiol glucuronide, testosterone glucuronide and 17β-estradiol, which have also been hypothesized to function as pheromones in fish. 5. The olfactory thresholds of goldfish tol-amino acids and taurocholic acid were similar to other species of fish: approximately 10−13M forl-serine and 10−9M forl-cysteine and taurocholic acid. 6. The olfactory sensitivities of mature male, mature female and gonadally-regressed fish were similar to all compounds tested suggesting that differences in olfactory receptor function are not responsible for the fact that only mature males exhibit behavioral and endocrine responses to pheromonal 17,20P.

Rainbow trout (salmo gairdneri) stocking and contracaecum spp.

Abstract: A stocking program with rainbow trout (Salmo gairdneri) at High Rock Lake, Manitoba failed due to infections with large numbers of Contracaecum spp larvae Nematode larvae in the intestinal tract, body cavity and musculature made the fish unmarketable A combination of experimental infections of rainbow trout and pelicans (Pelecanus erythrorhynchos), observations on the behavior of fish-eating birds, and numbers of larval Contracaecum spp in minnow species led to the following conclusions The introduction of rainbow trout attracted large numbers of fish-eating birds, particularly pelicans Concurrent predation by rainbow trout on fathead minnows (Pimephales promelas), five-spined sticklebacks (Culaea inconstans), and nine-spined sticklebacks (Pungitius pungitius), concentrated the parasites The combined increase in densities of the introduced fish host and fish-eating birds, and the short life cycle of the parasite, increased the numbers of parasites in rainbow trout over a season and in the indigenou

Flight and copulation of female spruce budworm in pheromone-permeated air.

Abstract: High concentrations of synthetic sex pheromone caused increased flight activity among mated female spruce budworm of all ages, a fact that may indicate an increase in dispersal. Flight activity also increased among older virgin females, but not among females one day old, the age at which they usually mate. Receptivity of young virgin females to courting males was not affected by pheromone-permeated air. Synthetic sex pheromone is therefore not likely to influence mating frequency through its effects on female activity.

Lack of bioaccumulation of metals by Elliptio complanata (Bivalvia) during acidic snowmelt in three south-central Ontario streams.

Abstract: Depression of pH and elevation of metals during spring snowmelt may be widespread. However, because of the episodic nature of these events they are very difficult to measure or even detect. Sampling of snowmelt at regular intervals of only a few days, may not be adequate to detect short-term variations in pH and metal concentrations. The objective of the present study was to determine the feasibility of using biomonitoring to detect short-term changes in concentration or bioavailability of metals (Al, Zn, Cd) during spring snowmelt. Unionid clams, (Elliptio complanata) were held in three south-central Ontario streams during the spring snowmelt period of 1982. The gill tissues accumulate metals more readily than other tissues and thus are better biomonitors of available metals than whole body concentrations of these elements. Therefore, the concentration of metals in soft tissues (gill, body, foot) were compared separately to the stream water chemistry during snowmelt.

A comparison of commonly used hydrologic design methods for rainwater collectors

Abstract: Rainwater collection as a possible water source in developing countries is introduced. The major parameters in calculating the size of the tank are defined. Six methods that have been used previously to relate demand, storage, reliability and the rainfall pattern are compared to the Ottawa Model over a wide range of demands.

Mixture Toxicity Indices in acute lethal toxicity tests

Abstract: The use of Mixture Toxicity Indices (MTI's) is one of the more attractive approaches for describing and predicting the effects of mixtures of toxicants. For an MTI to apply to all possible mixtures of the compounds in question, it must summarize information from a model describing all possible responses of interest. A method of obtaining MTI's from response surface equations or from tolerance models similar to the toxic units model is presented. Methods of calculating several MTI's with desirable properties from multivariable probit response surfaces are demonstrated.

A Multipath RF Propagation Model for Computer Simulation of Complex Impulse Responses of Broadcast Teletext Channels

Abstract: To accurately predict the performance of broadcast teletext systems, one must know the characteristics of typical over-the-air broadcast television channels. Consequently, ensembles of typical complex impulse responses of broadcast teletext channels in the VHF and UHF frequency ranges are required for computer performance simulations. To circumvent the lack of comprehensive measured channel data, a theoretical multipath propagation model for suburban and urban environments was developed to gain insight into the nature of typical television multipath channels. In this model, both the direct and scatter paths consist of a line-of-sight and ground-reflected component. The basis of the propagation model is an expression for the ratio of the scattered path to direct path field strength caused by vertically oriented dielectric slabs of specified thickness, height, and width. The reflector location, orientation, width, height, and thickness are randomized for each Monte Carlo simulation cycle. A scatter table of relative amplitude versus multipath delay is maintained for subsequent analysis and formation of typical multipath channel impulse responses. A perceived desired-to-undesired ratio (PDUR), which is essentially a signal-to-clutter ratio, is computed to eliminate channels of unacceptable video quality, as these would be of no interest to the teletext application. A modification to account for near-field scattering is described. Finally, mobile channel applications are discussed.

Influence of formulation properties on droplet size spectra and ground deposits of aerially-applied pesticides

Abstract: The influence of the physical properties of the spray liquid on droplet size spectra and ground deposits of aerially-applied pesticides was studied using heavy (high-viscosity) oil- and water-based suspensions of wettable powders (w.p.), a clear solution in a light (low-viscosity) oil, and an emulsion-suspension containing a bacterial control agent. The heavy oil provided a highly viscous spray medium, 52 to 64 mPa s (at a shear rate of 480 s−1), resulting in large droplet sizes and a high deposit on the ground sampling units. When the spray medium was thickened with petroleum jelly to keep the w.p. in suspension during overnight storage, the viscosity became excessively high (102 mPa s at 480 s−1), and the droplet spectrum was undesirably coarse and resulted in poor coverage of the spray plot and low deposits. The light-oil-based solution (ca 4 mPa s), provided a finer droplet spectrum and lower deposits than the heavy-oil-based formulations. The water-based suspensions of the w.p. (ca 2 mPa s), showed Newtonian behaviour, whereas the emulsion-suspension (ca 240 mPa s at 480 s−1) showed pseudoplastic behaviour. Consequently, the emulsion-suspension provided a markedly different droplet spectrum from that of the suspensions of the w.p. Nevertheless, all three aqueous media provided deposits comparable to those of the light-oil-based solution, markedly lower than the heavy-oil-based suspensions. The study indicated that highly viscous Newtonian formulations should be avoided in pesticide applications using Micronair AU3000 atomisers at the volume rate (4–7 litre ha−1) used here if high atomisation efficiency is required.

Gustatory Responses to Tetrodotoxin and Saxitoxin in Rainbow Trout (Salmo gairdneri) and Arctic Char (Salvelinus alpinus): A Possible Biological Defense Mechanism

Abstract: Pufferfish toxin, tetrodotoxin (TTX), is a potent neurotoxin, with its lethal toxicity to humans 300 times that of KCN. TTX exerts its toxic action by specifically blocking the voltage-sensitive sodium channels in nerve and muscle membranes.' TTX is widely distributed in tetraodontid fishes, but its distribution seems much wider than originally thought. Although much information is available on the mechanism of its pharmacological action, little is known about its biological significance. The presence of the fish toxin presents some interesting questions: DO possessors have any adaptive significance, or do predators benefit as toxins act as warning signals emanating from prey? Some pufferfish release TTX into surrounding water when stimulated by electric shock or stressed by handling.' Our recent behavioral studies demonstrated that some fish species avoid food containing TTX, suggesting that fish may be able to detect TTX via the gustatory system (Yamamori et al., unpublished). Saxitoxin (STX), a paralytic toxin, has also been found in some puffertish species,' and its pharmacological action is identical to that of TTX. This study was designed to describe the gustatory sensitivity of rainbow trout and arctic char to TTX and STX by measuring the integrated electrical responses from the palatine nerve innervating the palate and inside upper lip.

Influence of formulation on spray deposit patterns, dislodgeable and penetrated residues, and persistence characteristics of fenitrothion in conifer needles

Abstract: The influence of formulation on spray droplet spectra, deposit patterns, dislodgeable and penetrated residues, and persistence characteristics of fenitrothion in balsam fir needles was studied using three formulations containing different types of adjuvant. Spray was applied on to potted trees under controlled conditions in a laboratory chamber. Droplet size spectra and deposits were assessed using “Kromekote” cardlglass plate units. Foliar residues were measured by gas-liquid chromatography. The formulation containing polymeric adjuvants provided significantly larger droplets and higher foliar residues than those containing surfactants and co-surfactants. It also provided a higher ratio of dislodgeable-to-penetrated residues, and a slower initial rate of loss of fenitrothion. None of the formulations posed a long-term persistence problem because only very low amounts remained on foliage at 42 days post-treatment. The significance of these findings in terms of the possible increase in bioavailability of the pesticide via crawling contact is discussed.

Use of a Spatial Field Technique for the Analysis of Active MMICS

Abstract: The method of moments is applied for the first time to the analysis of active MMICs. A description of the procedure is presented and the analysis of two different amplifier configurations is compared with experimental results. This spatial field technique can be applied to both individual monolithic elements and complex MMICs with the advantage that interelement coupling is automatically taken into account.

Low angle signal fading at 38 GHz in the High Arctic

Abstract: In 1984 a microwave propagation experiment was conducted at 83\deg N latitude in Alert, Canada, to study the characteristics of low angle fading at a frequency of 38 GHz. By monitoring the continuous wave (CW) signal transmitted from the orbiting LES-8 satellite, propagation data were gathered over a range of elevation angles from 1\deg to 21\deg . A total of three sets of measurments were made in the spring, summer, and winter. These allowed comparisons to be made of the seasonal characteristics of low angle fading in the arctic. The experimental data were examined with respect to the atmospheric conditions observed at Alert. The results presented include the variation of the median signal level with the elevation angle, cumulative distributions of the received signal level and fade rate statistics. The amount of signal fading increased rapidly as the elevation angle decreased. Fading was most severe in the summer which also had the highest fade rates. Very little fading was observed in the winter.

The role of R&D in high-technology trade: An empirical analysis

Abstract: This paper attempts to establish the relationship between the level of R&D activities of a country and its trade performance in high-technology products Empirical evidence based on the limited data used in the paper shows that this relationship appears to be quite significant An analysis of the implications of this relationship reveals that the low level of R&D in Canada is due to, among other factors, the prevalence of foreign ownership of Canadian manufacturing industries, and the resource-based characteristic of the Canadian economy Given the nature of foreign-owned firms, the paper suggests that countries should not rely on them as a crucial instrument in the creation of an indigenous capacity to produce high-technology products which are competitive at the world level Instead, domestic policies aimed at the development and nurturing of the countries' own scientific and technological skills are required

Simultaneous determination of fenitrothion and aminocarb in blueberry foliage and fruits: Application to the analysis of residues in field samples

Abstract: Samples of blueberry foliage and fruits were collected from spray blocks in Ontario after aerial application of fenitrothion and aminocarb at dosage rates of 210 g active ingredient (AI)/ha and 70 g AI/ha respectively. Residues were extracted from the samples by homogenizing with ethyl acetate, cleaned up by microcolumn chromatography using alumina as adsorbent, and analyzed by GLC‐AFID with a glass column packed with 1.5% OV‐17 and 1.95% OV‐210 on 80–100 mesh Chromosorb W‐HP. Average recoveries for fenitrothion and aminocarb from foliage at three fortification levels (1.0, 0.10 and 0.01 ppm) were respectively 99 and 96%. The corresponding values for the fruits were 99 and 95%. Foliage samples collected 1 h post‐spray contained on average 1.13 ppm of fe‐nitrothion and 1.14 ppm of aminocarb. However, residue levels reached below the detection limit (<0.01 ppm) in foliage collected 15 d after treatment. In addition, the fruit samples collected after 15 d post‐spray contained extremely low levels (0...

Distribution and persistence of carbaryl in some terrestrial and aquatic components of a forest environment

Abstract: An oil‐based formulation of carbaryl (1‐naphthyl N‐methyl‐carbamate) (Sevin‐2‐Oil) was applied twice by a fixed‐wing aircraft at a dosage rate of 280 g of A.I./ha/application to a coniferous forest near Allardville, New Brunswick. The highest concentrations of the chemical in fir foliage, litter and forest soil 1 h after application were respectively 4.20, 1.21 and 0.59 ppm (fresh weight). The residues dissipated rapidly and the DT50 values obtained from the depletion curves were 2.3 d for foliage and 1.5 d for litter and soil samples. Very low levels (<0.1 ppm) of carbaryl persisted in foliage and litter beyond the 10 d sampling period. The maximum residue level found in stream water was 0.314 ppm and more than 50% of it had dissipated within 1 h. Low but detectable levels (0.001 ppm) of the chemical persisted in water until the end of the 10 d sampling period. Sediment samples contained a maximum level of 0.04 ppm, which dissipated below the detection limit within 5 h. Brook trout and slimy scu...

Cadmium contamination in American lobster,Homarus americanus, near a coastal lead smelter: Use of multiple linear regression for management

Abstract: In 1980 cadmium (Cd) concentrations in digestive gland from American Lobster (Homarus americanus), captured at Belledune Harbour, New Brunswick, Canada were found to range 47.6-372 mg/kg wet weight. Since the digestive gland is commonly eaten the harbor fishery was closed. The adjacent area was decreed a controlled fishery zone. The cadmium source was a lead smelter on the harbor shore. The company installed an aqueous effluent treatment plant and improved handling procedures within the plant area. Aqueous Cd discharges were subsequently reduced by more than 95%. Cadmium levels in lobsters have been monitored annually since 1980 by sampling in early spring, immediately after the lobsters emerged from their overwintering locations. The results from the 1981-1985 monitoring program were used to model the system, analyze the data and predict the years in which certain changes to the management plan might be implemented.

Effect of formulation properties on ground and foliar deposits of two insecticides in flushed and one year‐old balsam fir needles following aerial application

Abstract: A study was conducted in 1985 in Newfoundland to investigate the interrelationships between the physical properties of spray formulations, droplet-size spectra and deposits on ground sampling units, and deposits on flushed and one-year-old balsam fir foliage following aerial application of aminocarb and fenitrothion at different dosage rates, but using the same volume rates. The fenitrothion formulations were pseudoplastic, because of the presence of polymeric ingredients, and provided higher deposits on the ground sampling units and on foliage than the aminocarb formulations, which were nearly Newtonian. At similar dosage rates, the ground deposits of fenitrothion were about twice those of aminocarb, whereas the corresponding foliar deposits were about 6 to 8 times higher than those of aminocarb, suggesting possible advantages of pseudoplastic formulations in providing optimum droplet sizes for enhanced deposition on balsam fir needles. The foliar deposits generally showed an increase when the dosage rates of the two insecticides were increased. Deposits in flushed foliage were slightly higher than those in mature foliage, probably due to the location of the flushed needles at the extreme periphery of the tree canopy.

Influence of physical properties on droplet size spectra and deposit patterns of two mexacarbate formulations, following spray application under laboratory and field conditions

Abstract: The influence of viscosity, density, surface tension, volatility and apparent viscosity-shear rate relationship on droplet-size spectra and deposit characteristics of two mexacarbate (4-dimethylamino-3,5-xylyl methylcarbamate) formulations, one oil-based and one water-based, was studied following spray application under laboratory and field conditions. The oilbased formulation had a higher viscosity, a higher apparent viscosity at high shear rates and a lower volatility than the water-based formulation; application through rotary atomisers gave larger droplet sizes, more droplets cm−2 and deposits of the active ingredient ha−1 than those from the water-based formulation in both the laboratory and field studies. Both formulations had similar surface tensions and densities and, therefore, the contribution of these properties to droplet-size spectra could not be determined. Among the three properties (viscosity, apparent viscosity-shear rate relationship and volatility), volatility contributed most to the deposit patterns of the two formulations.

Intermolecular Interactions in Aqueous Pesticide Formulations from Viscosity-Temperature, Viscosity-Volatility, and Viscosity-Shear Rate Relationships

Abstract: A study of viscosity-temperature, viscosity-volatility, and viscosity-shear rate relationships was carried out for aqueous formulations of pesticides and adjuvants, in order to understand the influence of intermolecular interactions on physical properties. The data showed a general trend that highly viscous formulations exhibit high viscosity-activation energy, low volatility, and high pseudoplasticity, although there were many exceptions to this trend. The volatility data indicated that the mechanism of evaporation of water from the medium involves intermolecular forces that are different from those encountered in pseudoplastic behavior and viscosity changes with temperature. Among the four surfactants studied-Triton X-114, Triton X-100, Atlox 3409F, and Tween 80-Triton X-114 was unique in providing highly viscous and pseudoplastic formulations. The study also indicated that a highly viscous formulation with low pseudoplasticity may pose problems in flowability and fine atomization in the nozzle systems. A high evaporation rate implies rapid evaporation of water from the fine droplets emitted in ultralow-volume (ULV) applications, indicating the potential for off-target drift problems.

Influence of temperature on physical properties of non-aqueous pesticide formulations and spray diluents: relevance to u. l.v. applications

Abstract: The viscosity, surface tension and volatility of a range of ultra-low-volume (ULV) spray diluents and pesticide formulations were measured at 5°C and 20°C. For u.l.v. application of 1.0 to 1.5 litre ha−1 through conventional boom and nozzle systems or rotary (Micronair) atomisers, it is concluded that the spray medium should have a viscosity of ⩽30 mPa s at 20°C. The surface tension values covered only a narrow range and showed little temperature dependence. There was no clear optimum and all surface tensions within the range measured would appear to be acceptable for ULV applications. The volatility factor, 1/(A.T1/2), where A represents the percentage of non-volatile material in the spray mixture and T1/2, the half-life (minutes) of evaporation, should be <40 times; 10−5.

Optimizing physical properties of diluent oils for maximum target deposition of ultralow-volume spray droplets under laboratory conditions

Abstract: The influence of absolute viscosity, surface tension, volatility, apparent viscosity-shear rate relationship, and distillation point on droplet size spectra and deposit characteristics was investigated for a wide range ofpetroleum and vegetable oils used in pesticide sprays, using Kromekote cards and glass plates for droplet collection. Air samplers were also used simultaneously to assess the airborne concentrations of the materials. The results indicated an increasing trend in absolute viscosities and surface tensions, and a decreasing trend in volatilities of the diluent oils, as their distillation points increased. However, the relative rate of increase in absolute viscosities was greater than that in surface tensions. As a result, the inverse relationship between viscosity and volatility was much more pronounced than the one between surface tension and volatility. The apparent viscosities of the volatile oils at high shear rates were very much lower than those of the nonvolatile oils, indicating a marked difference in the intermolecular forces of attraction. The droplet size spectra, and thus the deposit characteristics, and airborne concentrations of the diluent oils varied depending on their absolute viscosities, volatilities, and apparent viscosities at high shear rates. The droplet size spectra of the highly volatile oils consisted of very small sizes, and as the volatility decreased gradually, a progressive increase in the droplet sizes and deposits was observed. The most satisfactory combination of droplet size spectra, droplets per unit area, and spray volume deposits, and that with the least amounts of airborne concentrations, was obtained with the Dowanol TPM solvent, which was also the least volatile of the eight volatile oils studied.

Limits on Cation Leaching of Weakly Podzolized Forest Soils: An Empirical Evaluation

Abstract: Chemical properties of two weakly podzolized sandy soils, one a Humo-Ferric Podzol, the other a less well-developed Dystric Brunisol, both from beneath mid-aged jack pine (Pinus banksiana Lamb.) Stands in northern Ontario, Canada, are given. In a 7 1/2-year-old column-lysimeter experiment (reported elsewhere), it had been noted that both soils, but the Podzol in particular, initially exhibited strong resistance to SO4 2− leaching. A hypothesis of anion immobilization by SO4 2− adsorption was advanced. Data to support the hypothesis are presented in the present paper on SO4 2− adsorption characteristics of the two soils. During the initial phase of SO4 2− loading to these soils, cation leaching is effectively blocked by selective removal of SO4 2− ions from the leaching solution and their adsorption chiefly into the Bf1 or Bm1 horizons, and the leaching solution is thereby robbed of counterions. Once SO4 2− adsorption capacity is reached, bases move freely with surplus SO4 2− ions, with the Chief limitation to removal being the upper limit imposed by the supply of exchangeable ions themselves. Evidence suggests that prolonged exposure to acid Solutions may result in increased weathering of silicate minerals of sufficient magnitude to compensate eventually for losses associated with the stripping of exchangeable reserves.

Data protection legislation in Canada

Abstract: (1987). Data protection legislation in Canada. International Review of Law, Computers & Technology: Vol. 3, No. 1, pp. 79-96.

Fuse-pull-and-taper monomode-fiber directional couplers: coupling mechanisms and pull signature diagnostics

Abstract: Directional couplers fabricated by the fuse-pull-and-taper technique can be made from either two identical fibers or two dissimilar (in diameter and refractive-index profile) fibers.1 The latter device is termed a tuned-port coupler and has interesting wavelength-selective properties.2 We present evidence that the power-transfer mechanism in the dissimilar fiber splitter reported in Ref. 1 is due to a new coupling mechanism. We also report the automated manufacture and characterization of fused directional couplers and the application of the characteristic curve of power transfer vs coupler length (i.e., its pull signature) to the optimization of the fabrication process.