Showing papers by "Government of Canada published in 1985"

Bioconcentration of cypermethrin, deltamethrin, fenvalerate and permethrin by Chironomus tentans larvae in sediment and water

Abstract: Comparaison de la bioconcentration des pesticides chez des insectes exposes directement au sediment contamine ou se trouvant dans l'eau situee au-dessus du sediment pour pouvoir suivre la vitesse de decontamination apres transfert en eau propre

Acidification and alkalinization of lakes by experimental addition of nitrogen compounds

Abstract: Fertilization of a small lake with ammonium chloride for four years as part of a eutrophication experiment caused it to acidify to pH values as low as 4.6. Implications for acidification of lakes via precipitation polluted with ammonium compounds are discussed. When phosphate was supplied with the ammonium, biological nitrogen uptake, apparently by phytoplankton, was the main mechanism causing acidification. When ammonium was applied without phosphate, it accumulated to high concentrations in solution, after which nitrification caused rapid acidification. In both cases, the whole-lake efficiency of acidification was low, averaging about 13% of the potential acidification of supplied ammonium chloride (Table 2). Subsequent application of phosphate plus sodium nitrate for two years caused the pH of the lake to increase. The efficiency of alkalinization was higher than for acidification, averaging 69% of the potential alkalinization of the supplied sodium nitrate.

Quantitative field investigations of feeding and territorial behaviour of young-of-the-year brook charr, Salvelinus fontinalis

Abstract: Direct observations of young-of-the-year brook charr, Salvelinus fontinalis, in a second-order woodland stream indicated that most of their feeding effort was directed toward sub-surface, drifting prey (83% of feeding time). Feeding from the substrate and water surface was much less frequent (17% of feeding time). Comparisons of gut contents to drift net and substrate fauna samples corroborated that the most commonly consumed prey (chironomid and trichopteran larvae, ostracods, and ephemeropteran nymphs) were captured primarily from sub-surface, invertebrate drift. The disproportionate numbers of some prey species in the guts of several fish indicate that some prey selection occurred. Territories appeared to be cardioid-shaped, and were often contiguous, with dominance hierarchies evident among the residents. Agonistic interactions were frequent. Charges and chases predominated (91% of interactions) while lateral displays were infrequent (9% of interactions). Overall, these fish spent most of the daylight hours station-holding (77%) and feeding (18%). While only 3% of total time was spent in aggression, this amounted to 14% of the time a fish spent away from its station. There was some indication that territories were defended at a cost of feeding time.

Modal-insensitive biconical taper couplers

Abstract: The modal-insensitive coupler consists of a number N of optical multimode fiber lengths, each fiber length having a core of initial predetermined cross-sectional area. The fiber lengths are fused together in a coupling section such that the cores of the fiber lengths have a reduced cross-sectional area in the coupling section which supports a minimum number of modes of optical energy at a predetermined wavelength, and such that the fiber lengths have different core cross-sectional areas to produce preselected coupling ratios.

Reactions of 15N-labelled urea with jack pine forest-floor materials.

Abstract: Urea, labelled with15N, was applied, at rates equivalent to 0–400 kg N ha−1, to mixed L + F horizon soil materials from a jack pine (Pinus banksiana Lamb.) forest. The L + F materials were held at 13°C and 33 kPa moisture in three experiments lasting from 6 to 128 days. In the first experiment the immobilization of fertilizer N was determined, in the second the stimulation of microbial activity was measured, and in the third urea reactions in a forest floor without microorganisms were examined. Urea stimulated microbial activity and microbial mineralization of soil N. Total amounts of N immobilized and recovered as organic N, after 128 days, increased with rate of application from 50 to 400 kg urea-N ha−1. The pH and C contents of water extracts of soil increased with increasing rates of urea application. Organic matter in a forest floor treated with urea was shown to solubilize after microbial activity was inhibited by gamma radiation, and this suggests that chemical C release was brought on by the urea. Results from this study were consistent with the hypothesis that microbial activity in urea-treated soil is stimulated by increased availability of C in soil.

Flight speed of male spruce bud worm moths in a wind tunnel at different wind speeds and at different distances from a pheromone source

Abstract: . Flying male spruce budworm (Choristoneura fumiferana [Clem.]) moths responding to virgin females and to synthetic pheromone in a wind tunnel maintained a constant rate of upwind progress when held by moving optomotor cues at a constant distance from the pheromone source. When allowed to progress upwind to the source, however, they slowed their upwind speed progressively as they approached it. They also adjusted their flight speed to maintain similar rates of upwind progress at different wind speeds.

The Development of Cable Data Communications Standards

Abstract: Commercially successful application of data communications technology to coaxial cable distribution networks requires the creation of systems useful to large numbers of subscribers sharing common communications procedures. Furthermore, it is desirable, particularly in entertainment CATV networks, that subscriber ownership of some or all terminal equipment and peripheral attachments be possible since such ownership enables the sharing of capital costs between the network operator and the subscriber. Systems designers are led inescapably to the need for standard interfaces and protocols. The paper describes some of the major types of cable data systems currently under development for both institutional and entertainment network applications. Common to both is the concept of a local interface unit to act as a link between the subscriber's terminal equipment and the cable drop. The design of the drop-side interface of this unit raises some major standardization issues. Another important issue is that of compatibility between data and video channels where both types of services are offered on the same cable television plant. The major thrust of present standardization activity has been founded upon the open systems interconnection (OSI) reference model and has taken place within a joint CVCC/EIA committee on teletext and within the IEEE Project 802.6 subcommittee on metropolitan area networks. The paper reviews this activity and explains the principal issues to be resolved.

Fabrication of fused twin biconical taper singlemode fiber splitters: effect of unequal cladding diameters

Abstract: In this paper we report the results of an investigation of fused-biconical fiber splitters fabricated from fibers having unequal cladding diameters.

Mexacarbate residues in selected components of a conifer forest following aerial applications of oil‐based and aqueous spray formulations

Abstract: Mexacarbate (4‐dimethylamino‐3,5‐xylyl N‐methylcarbamate) insecticide has potential for use in spruce budworm (Choristoneura fumiferana Clem.) control operations in Canada. Its persistence and fate in balsam fir (Abies balsamea (L.) Mill.), litter and soil samples were studied by spraying aerially oil‐based and water‐based formulations, each at 70 g A.I./ha over a coniferous forest near Bathurst, New Brunswick. The oil‐based formulation gave the maximum concentration of the chemical in the substrates studied. In fir needles, the highest concentrations observed were 0.51 ppm and 0.19 ppm (fresh weight) for the oil‐based and emulsion formulations respectively, 1 h after application. The residue levels decreased very rapidly with a half‐life of approximately 5 h. Three and eight days after the spray application of the emulsion and oil formulations respectively, the concentrations of mexacarbate in foliage decreased to trace levels ( 0.008 ppm). Only very low levels of residue were detected in litter...

High Performance Liquid Chromato-Graphic Method For The Determination Of Permethrin Deposits In A Forestry Spray Trial

Abstract: A convenient and sensitive reversed-phase high performance liquid Chromatographie method has been developed for the determination of perraethrin [3-phenoxybenzyl (±)- cis,trans -3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate] insecticide. Various isocratic and gradient mobile phases, consisting of acetonitrile:water (CH3CN:H2O) and methanol:water (CH3OH:H2O) solvent systems at two flow rates, were tested to separate and quantify the Isoners of permethrin using octadecylsilyl (ODS) (Regis 5μ m) and octylsilyl (OS) (RP-8, 10 μ m) bonded columns. The optimal mobile phase for perraethrin using the ODS column was 70:30 (v/v) CH3CN:H2O mixture at flow rates of either 1.0 or 1.5 mL/min. The measurement was done with a UV detector at 200 nm and 50°C. The OS column gave a less satisfactory separation than the ODS. Gradient elution systems examined did not improve the iso-meric separation of perraethrin. Using the method developed, deposit levels obtained on various sampling units during a perra...

Determination Of Mexacarbate And Five Of Its Derivatives By High-Performance Liquid Chromatography

Abstract: A simple, sensitive and reliable analytical method has been developed and reported for mexacarbate (4-ditnethylamino-3,5-xylyl N-methylcarbamate) and five of its possible degradation products likely to be found in environmental samples using reversed-phase high-performance liquid chromatography with isocratic and gradient solvent systems. All chromatogram peaks were Identified through comparison to standards. The method has been used to identify and separate the six compounds from a mixture of the standards. It has been evaluated under different column conditions and with different mobile phases. Best resolution of the analytes was obtained by using a gradient solvent system consisting of CH3CN and H3O detecting at 200 nm and 30°C using a HP-RP8, 10 μ m, 20 cm 4.6 mm column.

Implementation of the Gold-Rabiner pitch detector in a real time environment using an improved voicing detector

Abstract: An implementation of Gold-Rabiner parallel processing pitch detector is described. Modifications to the original pitch detector that resulted in a more accurate voiced/unvoiced decision are presented. The modified pitch detector, along with all the tasks required by a real time, full duplex 2400 bit/s vocoder, have been implemented on a single Texas Instruments' TMS-320 microprocessor chip.

Microcomputer Graphics and Applications with NAPLPS Videotex

Abstract: The microcomputer-based videotex decoder terminal could be just what the videotex industry has been looking for Is it too soon to predict wedding bells for these converging technologies?

Distribution and persistence of aminocarb in stream water, sediment and fish after application of three Matacil formulations.

Abstract: Three aminocarb formulations, water‐based Matacil® 180F, oil‐based Matacil® 180F and oil‐based Matacil® 180D, were applied separately to the surface of a stream at 2.40 g a.i./min for 5 minutes. The highest aminocarb concentration in the top 1 cm of water was found 5 min after application of oil‐based 180F (5000 ppb). The next highest concentration was 1862 ppb found in the top 1 cm layer of water 3 min after application of oil‐based 180D, followed by 1306 ppb found 5 min after application of water‐based 180F. Residue accumulations were first observed in sediment at 3 min and in fish tissues 0.5 h after application. The levels of accumulation were in the order of water‐based 180F > oil‐based 180F > oil‐based 180‐D. After the application of water‐based 180F, the highest concentrations were 20.2 ppb in sediment after 5 min and 127 ppb in fish tissues after 3 h. Residues disappeared rapidly from all three matrices and could not be detected after a period of 3–25 h.

Gas sampling device

Abstract: The invention provides apparatus for injecting a sample of a fluid into a sealed pouch. The apparatus includes a framework and an injection needle for coupling to a source of the fluid to supply the fluid to the pouch. A drive mechanism is attached to the framework and is coupled to the injection needle for operation to move the needle between a withdrawn position and an engagement position with the needle moving along a first line of travel. A hopper is attached to the framework for containing a plurality of pouches in a stack, and a transport mechanism is attached to the framework and has a shuttle moveable along a second line of travel at right angles to the first line of travel. The shuttle moves pouches one at a time from the hopper to a position in line with the needle to receive the sample from the needle with the needle in the engagement position. The mechanism also includes an ejection means coupled to the framework and operable to push the pouch off the shuttle to make room for another pouch from the hopper and a control means coupled to the drive mechanism, transport mechanism and ejection means to operate the parts of the apparatus in sequence.

Degradation and metabolism of mexacarbate in two types of forest litters under laboratory conditions

Abstract: The degradation and metabolism of mexacarbate were studied in two types (sandy loam and clay loam) of sterile and nonsterile forest litters after incubation for 45 days under aerobic and submerged conditions. Degradation of the chemical in non‐autoclaved litters was rapid initially and reached a maximum after 30 d. The rate of formation of 14CO2 and the amount, the extractable metabolites produced and the nonextractable 14C adsorbed onto the litters varied depending on the litter type and experimental conditions. Rate constants and half‐lives (t1/2) of evolution of 14CO2 were very similar for the aerobic and submerged conditions. However, the t1/2 values for the clay loam litter were slightly higher than those for the sandy loam litter. Litter microbes played a major role in the degradation of mexacarbate and formation of 14CO2. Metabolites detected included demethylated carbamates, various xylenols, polar and other unknown products. The principal degradative pathway for the chemical appears to b...