Showing papers by "Memorial University of Newfoundland published in 1987"
TL;DR: A systematic investigation of the viscerotopic organization of the nucleus ambiguus was undertaken in rats and found that the IXth, Xth, and XIth cranial nerves and the major branches of the Xth as well as organs supplied by them were innervated.
Abstract: The nucleus ambiguus has been reported to innervate various thoracic and abdominal viscera in addition to the musculature of the upper alimentary tract. However, the literature is contradictory as to how different regions of the nucleus ambiguus innervate specific organs. Therefore, a systematic investigation of the viscerotopic organization of the nucleus ambiguus was undertaken. In 102 rats, 0.5–10.0 μl of HRP, WGA-HRP, cholera toxin-HRP or fluorescent tracers were injected into the IXth, Xth, and XIth cranial nerves and the major branches of the Xth as well as organs supplied by them.
The results demonstrate that the nucleus ambiguus in the rat is made up of two major longitudinal divisions: a dorsal division comprised of three rostrocaudally aligned subdivisions representing the special visceral efferent component, and a ventral division comprised of at least two subdivisions representing the general visceral efferent component. The dorsal division corresponds to the nucleus ambiguus in the narrow sense and comprises a rostral esophagomotor compact formation, an intermediate pharyngolaryngomotor semicompact formation, and a caudal laryngomotor loose formation. Each of these formations displays a characteristic dendroarchitecture. The stylopharyngeal and cricothyroid motoneurons are displaced rostrad from the main pharyngeal and laryngeal motoneuronal pools. Thyropharyngeal (lower constrictor) motoneurons occupy the rostral half of the semi-compact formation and hyopharyngeal (middle constrictor) motoneurons its entire length. The ventral division of the nucleus ambiguus corresponds to the external formation, extends along the entire length of the medulla oblongata, and contains preganglionic neurons innervating the heart and supradiaphragmatic structures innervated by the glossopharyngeal and the superior laryngeal nerves.
525 citations
TL;DR: It is suggested that as an early warning system, the induction of mixed-function oxygenase (MFO) enzymes can fulfill the requirement of "most sensitive biological response" for assessing a variety of organic pollution conditions.
368 citations
TL;DR: Mussels, clams, and tube worms collected in the vicinity of hydrocarbon seeps on the Louisiana slope contain mostly "dead" carbon, indicating that dietary carbon is largely derived from seeping oil and gas.
Abstract: Mussels, clams, and tube worms collected in the vicinity of hydrocarbon seeps on the Louisiana slope contain mostly "dead" carbon, indicating that dietary carbon is largely derived from seeping oil and gas. Enzyme assays, elemental sulfur analysis, and carbon dioxide fixation studies demonstrate that vestimentiferan tube worms and three clam species contain intracellular, autotrophic sulfur bacterial symbionts. Carbon isotopic ratios of 246 individual animal tissues were used to differentiate heterotrophic (8(13)C = -14 to -20 per mil), sulfur-based (8(13)C = -30 to -42 per mil), and methane-based (8(13)C = <-40 per mil) energy sources. Mussels with symbiotic methanotrophic bacteria reflect the carbon isotopic composition of the methane source. Isotopically light nitrogen and sulfur confirm the chemoautotrophic nature of the seep animals. Sulfur-based chemosynthetic animals contain isotopically light sulfur, whereas methane-based symbiotic mussels more closely reflect the heavier oceanic sulfate pool. The nitrogen requirement of some seep animals may be supported by nitrogen-fixing bacteria. Some grazing neogastropods have isotopic values characteristic of chemosynthetic animals, suggesting the transfer of carbon into the background deep-sea fauna.
327 citations
TL;DR: It is established here that problems of phylogenetic inference based on the least-squares-fit criterion and the Farris'sf statistic are NP-complete and thus are so difficult computationally that efficient optimal algorithms are unlikely to exist for them.
214 citations
Journal Article•
186 citations
TL;DR: Samples from two localities near the crest of the Valu Fa ridge, an active back-arc basin spreading centre in the Lau Basin, consist of highly vesicular lava fragments of andesitic composition as mentioned in this paper.
144 citations
TL;DR: The results of one recent survey of white-footed mice living in different macrohabitats are consistent with the predictions of emigration cost, and Macrohabitat selection cost is easily incorporated into habitat selection theory and can be tested by linear regression techniques on isodars.
Abstract: Habitat selection costs depend upon the scale of habitat. At the fine-grained microhabitat scale, cost is linked to optimal foraging, and habitat selection should be abandoned even though fitness is greater in one microhabitat than in another. At the coarse-grained macrohabitat scale, cost is linked to emigration, and habitat selection should often be maintained even though fitness may be less in the ‘preferred’ macrohabitat than in others. Macrohabitat selection cost is easily incorporated into habitat selection theory and can be tested by linear regression techniques on isodars (lines of every point at which the fitness of individuals in one habitat equals that of individuals in another). The results of one recent survey of white-footed mice living in different macrohabitats are consistent with the predictions of emigration cost.
116 citations
TL;DR: In this article, side-scan data from the epicentral area of the 1929 Grand Banks earthquake and cores from the resulting turbidite are used to determine a sediment budget for the event.
Abstract: Side-scan data from the epicentral area of the 1929 Grand Banks earthquake and cores from the resulting turbidite are used to determine a sediment budget for the event. The 1929 turbidite has a volume of about 185 cubic km, which is mostly sand. Features indicating failure on the continental slope are observed only in muddy sediment. A major source of sand in the heads of the fan valleys of the Laurentian Fan is postulated to balance the sediment budget. This sand accumulated proglacially during the Wisconsinan glaciation and probably failed through liquefaction in the 1929 earthquake.
106 citations
TL;DR: In this article, the authors used electronic activity recorders to measure flight time, dive time, and time on the water of breeding Common Murres (Uria aalge) during both incubation and chick rearing.
Abstract: We used electronic activity recorders to measure flight time, dive time, and time on the water of breeding Common Murres (Uria aalge). During both incubation and chick rearing, about 90% of birds' time away from the colony was spent on the water or diving and 10% was spent flying. The proportion of flight time did not vary with trip duration. During chick rearing, 13.6% of time away from the colony was spent diving, and the proportion of time spent diving tended to decrease with trip duration. Potential foraging
ranges calculated from flight times during individual foraging trips showed a concave frequency distribution, and median potential ranges were 37.8 km for incubating birds and 5.4 km for chick-rearing birds. The use of electronic recorders to measure time budgets has broad applications for seabird energetics and foraging ecology and for the assessment of prey availability and abundance. Received 21 April 1986, accepted 13 October 1986.
103 citations
TL;DR: The published reports on the association between coffee consumption and cholesterol levels are insufficient to warrant public health admonitions against coffee drinking, but it may be of clinical importance in some hypercholesterolemic individuals.
99 citations
TL;DR: All labeled cells in the brain stem and cervical spinal cord observed following tracer injections into the thymus can be accounted for by spread of the tracer into surrounding structures, leading to spurious labeling.
Abstract: Central to the postulated relationship between the brain and the immune system has been evidence for the direct neural innervation of primary organs of the immune system. It has been reported previously that the thymus gland in rats and mice receives a substantial innervation from the "retrofacial" nucleus of the brain stem and ventral horn cells of the upper cervical spinal cord. Based on the proximity of the thymus to thoracic viscera and neck musculature known to receive motor fibers from these same areas of the brain stem and spinal cord, we examined the possibility that retrogradely labeled cells in the brain stem and spinal cord following injections of tracers into the thymus are due to spread of tracer into the esophagus and neck musculature. Small injections (0.5-2.0 microliter) of wheatgerm agglutinin-horseradish peroxidase (WGA-HRP) were made into the thymus, the esophagus, and the longus colli muscle of rats or mice. Also, the effects of a unilateral cervical vagotomy on cholinesterase activity in the thymus were examined. Finally, the source of the sympathetic supply to the thymus and the presence of catecholamine and cholinesterasic fibers in the thymus was reassessed. Injections of WGA-HRP into the thymus produced little or no labeling in the brain stem and spinal cord. In contrast, control injections into the esophageal wall resulted in numerous intensely labeled cells in the compact formation of the nucleus ambiguus, irrespective of the rostral-caudal level of the esophageal injection. Similarly, tracer injections into the longus colli muscle resulted in numerous intensely labeled cells in the ventral horn of the upper cervical spinal cord. Unilateral vagotomy did not alter cholinesterase activity in the thymus even though it was largely depleted in the ipsilateral nucleus ambiguus. The histochemical studies verified a major sympathetic innervation of the thymus gland. In keeping with this result, in animals in which no labeled cells were observed in the brain stem or spinal cord following thymus injection, labeled cells were, however, observed in the sympathetic chains from the superior cervical ganglia caudal to the T3 ganglia. In summary, all labeled cells in the brain stem and cervical spinal cord observed following tracer injections into the thymus can be accounted for by spread of the tracer into surrounding structures, leading to spurious labeling.(ABSTRACT TRUNCATED AT 400 WORDS)
TL;DR: An analysis is presented of a voltage source delta modulation (DM) inverter, which provides several advantageous characteristics over commonly used sine modulation process and provides low harmonics at the inverter output.
Abstract: An analysis is presented of a voltage source delta modulation (DM) inverter. The delta modulation method provides several advantageous characteristics over commonly used sine modulation process. It is relatively easy to implement and provides low harmonics at the inverter output. The inherent features of the delta modulation also provide control of ratio of voltage to frequency and commutation numbers of an inverter without much complexity in control circuit. These and other features of DM inverters are investigated theoretically and verified experimentally. Successful implementation of DM techniques in three-phase inverters are reported.
TL;DR: In this paper, a sequence of formation, established on the basis of the Port au Port Group, involves a rapid sea-level rise, which flooded the platform with shoreward-derived siliciclastic muds and resulted in the development of muddy tidal flats, and the gradual development of ooid shoal complexes, with decreasing rates of sea level rise.
Abstract: Large-scale sedimentary cycles, or Grand Cycles, are the most obvious features of the Port au Port Group in southwestern Newfoundland. Each cycle is interpreted to represent deposition in outer-platform, muddy tidal flats (lower shaly half-cycle) and ooid shoal complexes (upper carbonate half-cycle). Unpredictable metre-scale assemblages of oolite and carbonate laminite, constituting the carbonate half-cycles, are attributed to frequent migration of the shoal complexes in response to hydrographic factors such as tidal fluctuations and storms. Predictable metre-scale, shallowing-upward cycles of parted limestone and shale in the shaly half-cycles were probably controlled mainly by variable rates of carbonate sedimentation; a eustatic mechanism, however, cannot be discounted. Comparison with other North American Grand Cycles suggests a eustatic mechanism for Grand Cycle formation, possibly involving variations in the rate of sea-level rise. The interpreted sequence of formation, established on the basis of the Port au Port Group, involves (1) a rapid sea-level rise, which flooded the platform with shoreward-derived siliciclastic muds and resulted in the development of muddy tidal flats, and (2) the gradual development of ooid shoal complexes, which encroached onto the tidal flats, with decreasing rates of sea-level rise. In contrast to western North American examples, Newfoundland Grand Cycles are composed almost entirely of peritidal sediments; they are also thinner and have a smaller areal extent than do those in the west. These differences may be due to such factors as narrower shelves, slower rates of sedimentation, and lower amplitudes of sea-level rise on the present northeastern margin of the North American craton than on the western margin.
TL;DR: The change from a sequence of terrestrial and marine clastic sedimentary and volcanic rocks that show rapid lateral variability of thickness and facies to an overlying, essentially sheetlike, mainly carbonate sequence is interpreted to broadly define the Iapetus rift-drift transition (continental breakup) in the Appalachian miogeocline of western Newfoundland as mentioned in this paper.
Abstract: The change from a sequence of terrestrial and marine clastic sedimentary and volcanic rocks that show rapid lateral variability of thickness and facies to an overlying, essentially sheetlike, mainly carbonate sequence is interpreted to broadly define the Iapetus rift-drift transition (continental breakup) in the Appalachian miogeocline of western Newfoundland. Mafic dikes and granite in the lower sequence are dated isotopically at about 600 Ma. An Early Cambrian stratigraphic age for the base of the carbonate sequence suggests continental breakup and the onset of Iapetus sea-floor spreading at about 550–570 Ma. Stratigraphic analysis refutes models that assume a late Precambrian or earliest Cambrian wide Iapetus ocean in the northern Appalachians.
TL;DR: In this article, air-gun and 3.5-kHz seismic profiles from the eastern Aegean Sea off Turkey show that the continental shelf of outer Izmir and Candarli bays is formed by several superimposed deltaic sequences during times of lowered sea level associated with late Quaternary glaciations, deltas prograded seaward more than 60 km from their present positions.
TL;DR: Gonad output, reproductive effort and residual reproductive value are greater in scallops (Placopecten magellanicus) from shallow water, where conditions are more favorable, than in scalls from deep water as mentioned in this paper.
Abstract: Gonad output, reproductive effort and residual reproductive value are greater in scallops (Placopecten magellanicus) from shallow water, where conditions are more favourable, than in scallops from deep water. Variation between years in these fitness correlates is also greater in shallow water scallops. High reproductive effort is associated with a greater reproductive cost, although in general reproduction in this species appears to be “restrained”, and only in older individuals from shallow water is there evidence of “reckless” reproductive behaviour. Reproductive effort increases as the animal grows older, but residual reproductive value is a maximum at age 4 years, after which it decreases with age owing to greater mortality. Localities vary in their suitability for scallop growth and reproduction, and at one Newfoundland site conditions in shallow water (10 m) are better than those in deep water (31 m). Scallops from the former have a greater fitness than those from the latter. The energy costs of reproduction have implications for life history variability in P. magellanicus, although for a considerable part of its lifetime the scallop is able to maximise gamete production in response to environmental factors (especially the food supply) without trading off reproduction against growth or maintenance.
TL;DR: The present investigation addressed the problem of a social desirability response bias in measures of psychological well-being and results suggest that the high zero-order correlations between measures of well- Being and the Edwards scale are more readily attributed to content similarity between the Edwards Scale and measures ofWell-being.
Abstract: The present investigation addressed the problem of a social desirability response bias in measures of psychological well-being. Data on 150 people, between the ages of 50 and 82, yielded high correlations between three measures of well-being (the MUNSH, the LSI-Z, and the PGC) and the Edwards Social Desirability Scale, but only moderate ones between well-being scales and the Marlowe-Crowne Social Desirability Scale. Part correlations between well-being measures and an external criterion of happiness, controlling for social desirability, failed to improve on the zero-order criterion/well-being relationship. Controlling for social desirability, therefore, does not enhance the construct validity of well-being scales. These and related results suggest that the high zero-order correlations between measures of well-being and the Edwards scale are more readily attributed to content similarity between the Edwards scale and measures of well-being than to a social desirability response bias in well-being measures.
TL;DR: Increased fishing pressure could lead to the elimination of anadromous males from some populations because the mortality associated with parr maturation already leads to a loss of 60-70% of the male production in some commercial fisheries.
Abstract: result of increased fishing pressure (Gibson, 1978; Myers, 1983). Such increases are alarming because the mortality associated with parr maturation already leads to a loss of 60-70% of the male production in some commercial fisheries (Myers, 1984). If anadromous males are not necessary for the successful spawning of anadromous females, then increased fishing pressure could lead to the elimination of anadromous males from some populations. In view
TL;DR: In this paper, the authors examined the development of color preference in 20 newborns, 1-, and 3-month-olds, by recording their fixation time to blue, green, yellow, red, and gray squares at 2 luminances, 3 and 30 cd/m2.
Abstract: This study examined the development of color preference in 20 newborns, 1-, and 3-month-olds, by recording their fixation time to blue, green, yellow, red, and gray squares at 2 luminances, 3 and 30 cd/m2. Adults' ratings of the same stimuli were also obtained. The results showed that only newborns showed a brightness preference, looking longer at stimuli of lower luminance, but all groups preferred the chromatic over the achromatic stimuli. Adults and 3-months-olds showed a significant preference among the chromatic stimuli: 3-month-olds preferred the long-wavelength (red and yellow) to the short-wavelength (blue and green) stimuli, and adults demonstrated the opposite pattern of preference. These data imply that a preference for chromatic over achromatic stimuli exists at birth but that infants do not respond preferentially among different chroma before the third month.
TL;DR: It is suggested that some CTAs are mediated by emetic mechanisms and others are not, so that Garcia's hypothesis is not generally correct, but methodological and theoretical ambiguities make it premature to draw this conclusion.
Abstract: The conditioned taste aversion (CTA) literature is extensive, yet little is known about the mechanisms by which treatments induce CTA. This paper describes and evaluates Garcia's hypothesis (e.g., Garcia et al. 1985) that treatments produce taste aversions by activating the receptors and neural pathways proposed by Borison and Wang (1953) to underlie emesis. Research on the mechanisms by which various treatments induce emesis is reviewed and compared with similar research on CTA. Emetic mechanisms appear to be involved in the formation of CTAs produced by some treatments, but there is contrary evidence for other treatments. This suggests that some CTAs are mediated by emetic mechanisms and others are not, so that Garcia's hypothesis is not generally correct. However, methodological and theoretical ambiguities make it premature to draw this conclusion.
TL;DR: The results suggest that nurses need to develop a clear definition of their role in patient education, to validate patients' desires for teaching, and to examine organizational factors influencing their performance of the patient teaching role.
Abstract: The purpose of this study was to describe the amount of congruence in the perceptions of 38 matched nurse-patient dyads concerning the nurse's role in patient education. The perceptions of nurses and patients from two hospital settings were measured with two complementary sets of questions, developed for this study; t-tests were used to compare the mean responses of nurses and patients within and between the two settings to each set of complementary questions. The results indicated that incongruencies existed between nurses' and patients' perceptions of the nurse's role in patient education. Patients identified a general teaching function for nurses. When asked who they preferred to have teach them the specific information related to their condition, patients most frequently chose a physician. Nurses most frequently chose a nurse as the current and most desired patient teacher. Nurses incorrectly assumed that the desires of their patients for patient education were similar to their own. The results suggest that nurses need to develop a clear definition of their role in patient education, to validate patients' desires for teaching, and to examine organizational factors influencing their performance of the patient teaching role.
TL;DR: The broad, low-enthalpy transitions of dipolyenoic PC suggest that these lipids might have a very disordered gel phase, or that the transitions from the gel to the liquid crystal might proceed through some intermediate states.
TL;DR: Semi-purified cod trypsin was not as effective as puretrypsin in facilitating recovery of carotenoprotein from shrimp waste and the recovery ofcarotenobrotein fromrimp waste, during extraction at 4°C with or without trypsIn, was facilitated by EDTA.
Abstract: Atlantic cod trypsin or bovine trypsin were used to aid the extraction of carotenoprotein from shrimp wastes at 4°C. When 25 mg% cod trypsin was added to extraction medium containing 0.5N ethylene diaminetetraacetic acid (EDTA) 64% of the astaxanthin and 81% of the protein of shrimp waste was recovered as carotenoprotein in 24 hr. With 25 mg% bovine trypsin, under otherwise identical conditions, the carotenoprotein recovered represented 49% of the astaxanthin and 65% of the protein of the waste. Semi-purified cod trypsin was not as effective as pure trypsin in facilitating recovery of carotenoprotein from shrimp waste. The recovery of carotenoprotein from shrimp waste, during extraction at 4°C with or without trypsin, was facilitated by EDTA.
TL;DR: A suite of FORTRAN programs implementing this system for dense grid DEMs has been designed and used in various operating environments as discussed by the authors, where attention has been given to the methods used in the approximation of terrain concepts such as slope and relief.
TL;DR: Winter flounder from known locations were sorted according to their reproductive status about 4 weeks before spawning, and fish fed to satiation included some which had been initially designated non-reproductive post-mature.
Abstract: Winter flounder from known locations were sorted according to their reproductive status about 4 weeks before spawning. Five groups were then fed to satiation and three groups were not fed. The experiment was terminated at the end of the summer feeding season. At termination, only one of the recently spawned fish with restricted feeding showed gonad recrudescence. Conversely, all previously reproductive fish which had been fed to satiation showed gonad recrudescence. Fish fed to satiation included some which had been initially designated non-reproductive post-mature. These experiments indicate that a non-reproductive post-mature state is inducible and may be reversible, with the switch related to nutritional status.
TL;DR: In this paper, Strontium isotope ratios of tourmaline, piemontite, actinolite and scheelite mineral separates, characterized by Rb/Sr≤0.02, are concordant with respect to 87Sr/86Sr initial ratios over local sectors of the faults.
Abstract: Major structural discontinuities in the Abitibi greenstone belt acted as conduits for outgassing of the Archean crust, as reflected in fixation of a select group of lithophile elements including Si, C, K, Rb, Ba, Li, Cs, B and Pb, in metasomatized faults. For two of the largest structures, the Destor-Porcupine (DP) and Kirkland Lake — Cadillac (KC) fault zones ∼6×1015 g Si, 3×1015 g CO2 and 1015 g K were introduced into the faults during expulsion of an estimated 6×1018 g aqueous fluids. Strontium isotope ratios of tourmaline, piemontite, actinolite and scheelite mineral separates, characterized by Rb/Sr≤0.02, are concordant with respect to 87Sr/86Sr initial ratios over local sectors of the faults. The Sr isotope data record geographic variations which, from east to west on the KC fault is 0.7031–0.7041 (Val d'Or), 0.7008–0.7022 (Bourlemaque), 0.7017–0.7019 (Bousquet), 0.7029–0.7031 (Noranda), and 0.7013 to 0.7015 (Kirkland Lake). At Timmins, on the PD fault, 87Sr/86Sr initial ratios cluster at 0.7010 to 0.7020. Metasomatised fault zones are systematically more radiogenic than contiguous host lithologies, and imply a source reservoir (0.7010 to 0.7041) generally more radiogenic than the upper mantle at 2690 Ma (0.700±0.001), or contemporaneous volcanic rocks of mafic to ultramafic composition (0.700 to 0.7012). Whereas certain minerals are concordant and retentive, Rb-Sr isochrons based on suites of rocks at progressive intensities of metasomatism, have been systematically reset over an elpased time of ∼200 Ma after termination of outgassing, due to disturbance accompanying incremental displacements on structures.
TL;DR: Summer surveys of the incidental catch of marine birds and mammals in fishing nets around the east coast of Newfoundland indicated that over 100 000 animals were killed in nets during a 4-year period (1981–1984), with highest incidental catches occurred in conjunction with the inshore spawning migration of capelin.
TL;DR: The yellowtail antifreeze protein, in contrast to that of the winter flounder, contains a fourth 11-amino-acid repeat and lacks several of the hydrophilic residues that have been postulated to aid in the binding of the protein to ice crystals.
Abstract: The sequence and activity of antifreeze proteins from two right eye flounder species were compared to assess the influence of structural variations on antifreeze capacity. The cDNA encoding the major serum antifreeze protein in the yellowtail flounder (Limanda ferruginea) was cloned from liver tissue. Its DNA sequence shows that the precursor to the antifreeze is a 97-residue preproportion. Edman degradation identified the N-terminus of the 48-amino-acid mature serum antifreeze protein and confirmed the sequence of the first 36 residues. A comparison with the previously determined winter flounder antifreeze protein and mRNA sequences shows strong homology through the 5' and 3' untranslated regions and in the peptide region. The mature protein section has the greatest sequence variation. Specifically, the yellowtail antifreeze protein, in contrast to that of the winter flounder, contains a fourth 11-amino-acid repeat and lacks several of the hydrophilic residues that have been postulated to aid in the binding of the protein to ice crystals. Intramolecular salt bridges are present in the antifreeze proteins from both species but in different registries with respect to the 11-amino-acid repeats. On a mass basis the yellowtail flounder antifreeze, though longer than that of the winter flounder, is only 80% as effective at depressing the freezing temperature of aqueous solutions. This lower activity might be due to the reduced number of hydrophilic ice-binding residues per molecule.
TL;DR: In this paper, a discrete fracture simulation approach is presented that incorporates the statistics of the fracture system geometry in the hydrogeological analysis of a fractured rock mass, and the fracture generation program is based on the Monte Carlo method and uses the statistic of field data of fracture geometry, i.e. fracture orientation, trace length, aperture and density.