Showing papers by "Memorial University of Newfoundland published in 1986"
TL;DR: While the spring phytoplankton bloom in Newfoundland coastal waters is in progress during April and May, at water temperatures between -1� and +2�C, bacterial growth and respiratory rates remain low.
Abstract: While the spring phytoplankton bloom in Newfoundland coastal waters is in progress during April and May, at water temperatures between -1° and +2°C, bacterial growth and respiratory rates remain low. Microbial community respiration is not measurable at -0.2°C. Particulate materials that would be utilized by microorganisms in 2 to 3 days at 20° to 25°C require 11 days at 4°C and 18 days at -0.2°C. Thus, photosynthesis is active but microbial utilization of the products is suppressed. High secondary production in cold water may result from the low rate of microbial decomposition, enabling herbivores to utilize much of the primary production.
336 citations
TL;DR: The St George Group consists of peritidal carbonate rocks from the continental shelf of North America and the ancient Iapetus Ocean as discussed by the authors, which are similar to other lower Palaeozoic limestones and dolostones that accumulated in epeiric seas.
Abstract: The St George Group consists of peritidal carbonate rocks deposited on the continental shelf of North America bordering the ancient Iapetus Ocean. These Lower Ordovician rocks are similar to other lower Palaeozoic limestones and dolostones that accumulated in epeiric seas and veneer cratonic areas worldwide. A wide variety of facies in the St George is grouped into seven lithotopes, interpreted to represent supratidal, intertidal and shallow, high- and low-energy subtidal environments. Rapid lateral facies changes can be observed in some field exposures, and demonstrated by correlation of closely spaced sections. The stratigraphic array of these lithotopes, although too irregular to be simplified into shallowing-upward cycles, suggests that they were deposited as small tidal flat islands and banks. Shallow subtidal areas around islands generated sediment and permitted tidal exchange. Tidal flat islands were somewhat variable in character at any one time, and evolved with changing regional hydrographic conditions.
The St George rocks suggest an alternative theory of carbonate sedimentation in large, shallow epeiric seas, namely as small islands and banks built by processes that operated in a tidal regime. Furthermore, this island model provides a framework for a mechanism of cyclic carbonate sedimentation, by which small-scale, peritidal cycles represent tidal flat islands that accreted vertically and migrated laterally as local sediment supply from neighbouring subtidal areas waxed and waned during relatively constant subsidence.
240 citations
TL;DR: Bimodal associations of basalt and rhyolite of Upper Ordovician age which were erupted in a submarine environment occur within the Caledonian orogenic belt of South Britain at Parys Mountain (Anglesey), in Snowdonia (North Wales) and at Avoca (SE Ireland).
Abstract: Bimodal associations of basalt and rhyolite of Upper Ordovician age which were erupted in a submarine environment occur within the Caledonian orogenic belt of South Britain at Parys Mountain (Anglesey), in Snowdonia (North Wales) and at Avoca (SE Ireland). The volcanic rocks have experienced hydrothermal alteration and low-grade metamorphism, and therefore immobile elements (e.g. Ti, Zr, Nb, Y) have been used to identify the original geochemical characteristics. The basalts have characters transitional between volcanic ‘arc’ and ‘within plate’ types consistent with eruption on an extensional part of an active continental margin. Two groups of rhyolites have been identified. A low-Zr group (Zr 500ppm), represented at Snowdonia and Avoca, is interpreted as originally being peralkaline in composition; their high Zr/Nb ratios (>10) are typical of peralkaline rhyolites erupted above subduction zones. The bimodal nature of the associations and the peralkaline character of some rhyolites indicates magma production in a complex tectonic setting, transitional between an active continental margin/island arc and an extensional environment. Associated sulphide mineralization is volcanogenic and probably syn-sedimentary. High-level, rhyolitic magma chambers are thought to have driven convection of the hydrothermal fluids from which the sulphides precipitated.
167 citations
TL;DR: Avoidance of common dietary allergens during pregnancy and lactation enhanced the preventive beneficial effect of exclusive breast feeding on the incidence of atopic eczema among infants at high risk.
Abstract: One hundred and twenty-one women with history of a previous child with atopic disease were randomly allocated during the next pregnancy to antigen avoidance or control groups. Dietary advice consisted of almost complete exclusion of milk and dairy products, egg, fish, beef and peanut throughout pregnancy and lactation. A total of 109 completed the study. Maternal antigen avoidance was associated with reduced occurrence of atopic eczema and the skin involvement was less extensive and milder. The beneficial effect was observed mainly in the breast-fed group. Among the fifty-five who completed the trial of antigen avoidance, seventeen infants developed atopic eczema, five out of thirty-five who were breast-fed and twelve out of twenty who were formula-fed. Among the offspring of fifty-four control mothers given no dietary restriction, eczema was observed in twenty-four infants, eleven out of thirty-six breast-fed and thirteen of eighteen formula-fed. Avoidance of common dietary allergens during pregnancy and lactation enhanced the preventive beneficial effect of exclusive breast feeding on the incidence of atopic eczema among infants at high risk.
164 citations
TL;DR: In this paper, a permanent magnet motor with power semiconductor supply and shaft position sensing can be constructed using radially-directed high energy magnets on its rotor, and equivalent circuit models for such motors are presented.
Abstract: A permanent magnet motor with power semiconductor supply and shaft position sensing can be constructed using radially- directed high energy magnets on its rotor. This paper presents equivalent circuit models for such motors. The model parameters are related to the motor structure and dimensions. Computed values of parameters are compared with those measured from two experimental motors with different rotor construction.
155 citations
TL;DR: In this paper, a regression model for several vari¬ables under the assumption that the errors have a multivariate t-distribution is presented and the parameters of the model, the regression parameters, as well as the scale parameters and the degress of freedom of the error variable are estimated.
Abstract: This paper deals with a regression model for several vari¬ables under the assumption that the errors have a multivariate t-distribution. The parameters of the model, the regression parameters, as well as the scale parameters and the degress of freedom of the error variable are estimated and the estimation procedure is illustrated by a numerical example, Also, the prop¬erties of the estimators and tests for the regression parameters are discussed.
105 citations
TL;DR: The most probable ages of the grey gneisses are 3690 ± 50 Ma, white gneises at 3590 ± 40 Ma and pegmatitic gneses at 3370 ± 60 Ma.
100 citations
TL;DR: In this article, a simple theoretical model has been developed from first principles for cross flow induced fluid-elastic instabilities in heat exchanger tube bundles, which includes the effects of tube array pattern and pitch.
97 citations
TL;DR: There was a substantial increase in the levels of 17 alpha, 20 beta-P and its glucuronide in the males captured at the spawning grounds, and in both sexes gonadotropin levels were low during the migration and high in the postspawned fish.
95 citations
TL;DR: In the Isua supracrustal belt, Isukasia area, southern West Greenland, a c. 75 km2 augen of lower deformation is seen to comprise predominantly 3,750-3,700 Ma tonalitic grey gneisses that were intruded first by thin bodies of mafic to dioritic composition, known collectively as the Inaluk dykes, and then by c. 3,600 Ma white gneises and finally by sporadic 3,400 Ma pegmatitic gneisse sheets as discussed by the authors.
Abstract: Amphibolite facies early Archaean Amitsoq gneisses envelop and intrude the c. 3,800 Ma Isua supracrustal belt, Isukasia area, southern West Greenland. Most of these gneisses are strongly deformed, but in a c. 75 km2 augen of lower deformation, the Amitsoq gneisses are seen to comprise predominantly 3,750–3,700 Ma tonalitic grey gneisses that were intruded first by thin bodies of mafic to dioritic composition, known collectively as the Inaluk dykes, and then by c. 3,600 Ma white gneisses and finally by sporadic c. 3,400 Ma pegmatitic gneiss sheets. The grey gneisses could have formed by partial melting of crust consisting predominantly of basic rocks. The Inaluk dykes are interpreted as strongly fractionated basic melts of mantle origin, contaminated by crustal material. The white gneisses consist mostly of medium grained granite and occur as lenses and anastomosing sheets throughout their host of grey gneisses with subordinate inclusions of supracrustal rocks. The white gneisses have chemistry compatible with formation by partial melting at depth of a source dominated by grey gneisses. The igneous chemistry, including REE abundances, of the grey gneisses and white gneisses has been modified to varying degrees by metasomatism and assimilation reactions during the crystallisation of the white gneisses and also during subsequent tectonometamorphic events. The white gneisses are evidence for considerable reworking by anatexis of sialic crust in the early Archaean, 150 to 100 Ma after its formation. The white gneisses and the pegmatitic gneisses show that granitic rocks s.s. were important in the earliest Archaean, and are further evidence of the diversity of the oldest-known sial.
90 citations
TL;DR: The number of mucous-net layers in the feeding filter of Oikopleura vanhoeffeni collected from March 1985 to February 1986 is determined, and the pathway of water flow through the filter is described to be the “food concentrating filter”.
Abstract: Although the feeding apparatus of oikopleurid Appendicularia has been described in general, functional details of the feeding mechanism and fluid mechanical constraints on the feeding process remain unknown. My goals were to determine the number of mucous-net layers in the feeding filter of Oikopleura vanhoeffeni collected from March 1985 to February 1986, and to describe the pathway of water flow through the filter. Marker particles (i.e. Isochrysis galbana, carmine, charcoal powder, and starch), and rhodamine dye were added to the natural food suspension to help in visualizing structure and flow. The feeding filter was composed of three layers. Water flowed into the filter through two large, lateral openings at the base of each wing, and along the open distal margins of the filter. Under hydrostatic pressure generated by the tail, water moved through the filter in a one-way bulk flow and was forced through the mucous mesh of both the dorsal and ventral layers. Thus, the feeding filter concentrated the food suspension by sieving most of the incoming water. The filter did not collect or trap food particles. Because of its function, I propose calling the feeding filter the “food concentrating filter”.
TL;DR: A marine seismic reflection line across the northeast extremity of the Canadian Appalachians in Newfoundland indicates a collisional suture(?) in the lower crust beneath the central ophiolitic Dunnage terrane as mentioned in this paper.
Abstract: A marine seismic reflection line across the northeast extremity of the Canadian Appalachians in Newfoundland indicates a collisional suture(?) in the lower crust beneath the central ophiolitic Dunnage terrane. The thrust and fold belt (miogeocline) above the Grenville basement, and the Dunnage and Gander tectonostratigraphic terranes all appear to be allochthonous with respect to lower crustal basement. The Gander-Avalon terrane boundary to the east is a near-vertical feature that penetrates the crust. The data also suggest that the ancient passive margin of North America extends eastward under the Dunnage terrane for about 70 km. The Newfoundland deep seismic experiment indicates major tectonic differences compared to results for the southern Appalachians.
TL;DR: In this paper, the authors present a review of the research on the measurement and prediction of subjective well-being in later life and conclude that subjective wellbeing is the best predictor of itself.
Abstract: This paper reviews the research on the measurement and prediction of subjective well-being in later life. Psychometric data on several gerontological scales are presented in detail. Structural analyses of a variety of measures of subjective well-being are discussed and evidence for a one factor structural solution to subjective well-being is presented. Objective predictors of subjective well-being are discussed with respect to the strength of their relationships to subjective well-being. It is concluded that subjective well-being is the best predictor of itself. Evidence of temporal stability and corss-situational consistency, combined with the evidence of a one factor structural solution, suggests that subjective well-being has trait-like characteristics. Suggestions for future research are presented.
Journal Article•
TL;DR: The authors outline a regimen of regular screening for members at risk that has evolved as a result of their experience with this family.
Abstract: Von Hippel-Lindau disease, an autosomal dominant condition with complete penetrance, has been recognized in a large family that originated in Newfoundland but has some members who live in New Brunswick and Ontario A collaborative investigation was begun in 1982 to document the number of affected members and the extent of their disease and to improve management of the disease The condition has been documented in 38 members of the family, 28 living and 10 dead The most common manifestations are retinal angioma (present in 60% of the gene carriers) and pheochromocytoma (present in 53%) Of the 28 living affected members 14 had been identified before the study began Only 3 of the 14 patients in whom the disease was subsequently diagnosed presented with symptoms; in the remaining 11 the condition was detected by routine screening Overall the mean age at the time of diagnosis was 23 years; in the 21 affected members of the fourth generation it was 18 years The authors outline a regimen of regular screening for members at risk that has evolved as a result of their experience with this family
TL;DR: Theoretical stability threshold curves are determined for standard heat exchanger tube bundle geometries based on the first principles model developed in Part I. as mentioned in this paper, and an investigation into the sensitivity of the predicted threshold curves on variations in model parameters is also presented.
TL;DR: The effect of testosterone implantation on pituitaries of the Pacific chinook salmon and β-GTH mRNA was examined with radioimmunoassay and Northern blot analysis and there was a corresponding increase in both the pituitary GTH and mRNA levels.
Abstract: Gonadotropin (GTH) was purified from the pituitaries of the Pacific chinook salmon using a combination of stepwise ethanol precipitation and concanavalin-A affinity chromatography. The α and β subunits were dissociated and fractionated by C-18 reverse-phase high-performance liquid chromatography with a 0.1% trifluoroacetic acid/acetonitrile gradient. An enriched cDNA library was screened for the β-GTH gene(s) using two synthetic oligonucleotides based on partial protein data. A positive, full-size clone (E3) was identified and sequenced. It contains 657 base pairs and codes for a 142-amino-acid precursor protein. The mature salmon β-GTH (119 amino acids) is structurally homologous to human luteinizing hormone and chorionic gonadotropin. The effect of testosterone implantation on pituitary GTH and β-GTH mRNA was examined with radioimmunoassay and Northern blot analysis. There was a corresponding increase in both the pituitary GTH and mRNA levels.
TL;DR: The data suggest that physiological NE release via LC activation induces a beta receptor mediated facilitation of the perforant path-evoked population spike which parallels that obtained with direct application of NE to the DG in vivo or in vitro and may provide one mechanism in the mammalian brain for long-lasting heterosynaptic modulation of neural inputs.
Abstract: Norepinephrine (NE)-induced, long-lasting facilitation of the perforant path evoked population spike amplitude in the dentate gyrus (DG) has been reported to occur following iontophoresis of norepinephrine in the DG in vivo and following application of 10 or 20 μM NE to the hippocampal slice in vitro. The present study employs glutamatergic activation of the locus coeruleus (LC) to induce NE release in the DG. Thirty-three female rats served as subjects. The perforant path-evoked potential was elicited once every 10 s and monitored in the DG cell body layer. Following appropriate control periods, 100–150 nL of 0.5 M 1-glutamate were pressure ejected in the vicinity of the LC. All placements in or within 300 μM of the LC produced significant facilitation (140%) of the population spike amplitude. Facilitation lasted more than 20 min in 37% of the animals tested. The facilitation effects on population spike amplitude were replicated with up to four ejections of glutamate at the same site. Propranolol (30 mg/kg i.p.) blocked this facilitation of population spike amplitude. Changes in EPSP slope were variable. Glutamate-activation of LC was not accompanied by blood pressure increases. These data suggest that physiological NE release via LC activation induces a beta receptor mediated facilitation of the perforant path-evoked population spike which parallels that obtained with direct application of NE to the DG in vivo or in vitro. LC-NE may provide one mechanism in the mammalian brain for long-lasting heterosynaptic modulation of neural inputs.
TL;DR: Electrical stimulation of the locus ceruleus, a major norepinephrine‐containing nucleus in the brainstem, or of its axons projecting to the forebrain, the dorsal noradrenergic bundle, suppressed penicillin‐induced focal epileptiform activity but was less effective in suppressing focalPenicillin spikes.
Abstract: Summary: Application of penicillin to the cerebral cortex of anesthetized rats by pressure ejection from a micropipette resulted in the appearance of focal epileptiform activity with low rates of penicillin release and focal penicillin spikes with higher rates. Electrical stimulation of the locus ceruleus (LC), a major norepinephrine-containing nucleus in the brainstem, or of its axons projecting to the forebrain, the dorsal noradrenergic bundle, suppressed penicillin-induced focal epileptiform activity but was less effective in suppressing focal penicillin spikes. Depletion of monoamines with reserpine blocked the suppressant effect of LC stimulation. Neither the selective depletion of 5-hydroxytryptamine with p-chlorophenylalanine nor administration of methysergide reduced the effectiveness of LC stimulation, suggesting that 5-hydroxytryptamine probably does not mediate the suppression. Pimozide partially antagonized the suppression of focal epileptiform activity induced by LC stimulation, which is consistent with antagonism of α-adrenoceptors but not dopamine receptors. β-Receptor antagonists did not block the suppression of focal epileptiform activity by LC stimulation, suggesting that β-receptors are not important in the observed suppression. Prazosin, a selective α1-antagonist, at low doses blocked the suppression of focal epileptiform activity by LC stimulation whereas yohimbine, an α2-antagonist enhanced the stimulation-induced suppression. Taken together, the data are consistent with LC and dorsal bundle stimulation releasing norepinephrine, which in turn suppresses focal epileptiform activity by an action mediated by an α1-adrenoceptor.
RESUMEN
La aplicacion de penicilina a la corteza cerebral de ratas anestesiadas por eyeccion a presion mediante una micropipeta produce la aparicion de actividad epileptiforme focal con dosis lentas de penicilina y puntas con dosis frecuentes. La estimulacion electrica del locus coeruleus (LC), uno de los principales nucleos contenedores de norepinefrina del tronco cerebral, o de sus axones que se proyectan al cerebro anterior, el fasciculo noradrenergico dorsal, suprimia la actividad epileptiforme focal penicilina-inducida pero fue menos efectiva para la supresion de las puntas focales por penicilina. La depleccion de monoaminas con reserpina bloquea el efecto supresivo de la estimulacion del LC. Ni la depleccion selectiva de 5-hidroxitriptamina con p-clorofenilalanina, ni la administracion de metisergida disminuyeron la efectividad de la estimulacion del LC, sugiriendo que la 5-hidroxitriptamina probablemente no interviene en la supresion. El pimozide antagoniza parcialmente la supresion de la actividad epileptiforme focal inducida por la estimulacion del LC lo cual es consistente con antagonismo de los adrenoreceptores alfa pero no de los receptores de dopamina. Los antagonistas de los receptores beta no bloquean le supresion de la actividad epileptiforme focal por estimulacion del LC mientras la yohimbina, un antagonista alfa2 aumenta la supresion inducida por estimulacion.
ZUSAMMENFASSUNG
Die Verabfolgung von Penicillin auf den cerebralen Cortex anasthesierter Ratten durch Druck aus einer Mikropipette fuhrte zum Auftreten fokaler epileptiformer Aktivitat bei niedrigen Raten der Penicillinfreisetzung und fokalen Penicillin-spikes bei hoherer Freisetzungsrate. Elektmische Stimulation des Locus coeruleus (LC), einem uberwiegend Norepinephrin enthaltenden Kern des Hirnstammes oder seiner in das Vorderhirn projezierenden Axone, die dorsalen noradrenergen Bundel, unterdruckte die Penicillin-induzierte fokale epileptiforme Aktivitat; sie war aber weniger wirkungsvoll in der Unterdruckung fokaler Penicillin-spikes. Die Erschopfung der Monoamine durch Reserpin blockierte die unterdruckende Wirkung der LC-Stimulation. Weder die selektive Erschopfung von 5-Hydroxytryptamin durch Parachlorophenylalanin, noch die Anwendung von Methylsergid reduzierten die Wirksamkeit der LC-Stimulation. Das deutet darauf hin, das 5-Hydroxytryptamin wahrscheinlich die Unterdruckung nicht vermittelt. Pimozid wirkt der Unterdruckung der fokalen epileptischen Aktivitat nach LC-Stimulation teilweise entgegen; das ist mit dem Antagonismus der alpha-Adrenozeptoren aber nicht der Dopamin Rezeptoren zu vereinbaren. Beta-Rezeptor-Antagonisten blockierten die Unterdruckung der fokalen epileptiformen Aktivitat nach LC-Stimulation nicht, was dafur spricht, das beta-Rezeptoren fur diese Unterdruckung nicht wichtig sind. Prazosin, ein selektiver alpha-1-Antagonist blockierte in niedriger Dosis die Unterdruckung der fokalen epileptiformen Aktivitat nach LC-Stimulation, wahrend Yohimbin, ein alpha-2-Antagonist, die Unterdruckung nach Stimulation verstarkte.
TL;DR: The results suggest that species recognition in rock bass is controlled by a closed genetic program and that social experience is not necessary, and interspecific differences in recognition abilities may be related to differences in habitat and group parameters among the species.
Abstract: We conducted laboratory experiments to determine if juveniles of three species of centrarchid fishes displayed abilities for species or individual recognition. In one experiment we reared rock bass (Ambloplites rupestris) in social isolation and in social groups. Both the isolated and group-reared fish spent significantly more time close to conspecifics than to heterospecifics. These results suggest that species recognition in rock bass is controlled by a closed genetic program and that social experience is not necessary. A second set of experiments was conducted to determine if year-old blue-gill (Lepomis macrochirus), pumpkinseed (L. gibbosus), and rock bass juveniles could discriminate between familiar and unfamiliar conspecifics. Bluegill spent significantly more time with familiar conspecifics than with unfamiliar conspecifics, while the other two species displayed no such trend. Bluegill spent significantly more time with familiar conspecifics than did either of the other two species. We postulate that these interspecific differences in recognition abilities may be related to differences in habitat and group parameters among the species.
TL;DR: It is suggested that bacteria from humans should be examined for resistance to apramycin and gentamicin to determine the possibility of the antibiotic-resistance bacteria, and their genes, spreading from animals to humans.
Abstract: Since the aminoglycoside antibiotic apramycin was licensed for veterinary use in 1980, all isolates of Escherichia coli and salmonellas received at the Central Veterinary Laboratory have been monitored for resistance to apramycin and the related antibiotic gentamicin. During the period 1982-4, the incidence of resistance in E. coli to apramycin increased from 0.6% in 1982 to 2.6% in 1984. In salmonellas the incidence of resistance to apramycin increased from 0.1% in 1982 to 1.4% in 1984. Resistance to both apramycin and gentamicin was detected in six different salmonella serotypes, although an isolate of Salmonella thompson from poultry was resistant to gentamicin but not apramycin. Most of the cultures were isolated from pigs, although the incidence of apramycin resistance in S. typhimurium (DT 204C) from calves has shown a recent dramatic increase. All the isolates with one exception produced the enzyme aminoglycoside 3-N-acetyltransferase IV (ACC(3)IV). The resistance was transferable by conjugation in most of the strains examined, and the plasmids specifying the resistance have been found to belong to a number of different incompatibility groups. Plasmids from three E. coli strains were compatible with all the reference plasmids and belonged to a previously undescribed group which was investigated further. It is suggested that bacteria from humans should be examined for resistance to apramycin and gentamicin to determine the possibility of the antibiotic-resistance bacteria, and their genes, spreading from animals to humans.
TL;DR: In this article, the authors study likelihood ratio tests for a set of k normal means when both the null and alternative hypotheses impose homogeneous linear inequality constraints on the means. Examples of such constraints include hypotheses that the means are equal, nonnegative, that they are linear or monotone.
Abstract: Likelihood ratio tests for a set of k normal means are studied when both the null and alternative hypotheses impose homogeneous linear inequality constraints on the means. Examples of such constraints include hypotheses that the means are equal, that they are nonnegative, that they are linear, or that they are monotone. Several tests involving such constraints have appeared recently, and here we present theory that unifies and extends many of these results. Our approach makes use of the properties of polyhedral cones. We define conditions under which the exact distribution of the likelihood ratio statistic is available, and show that this distribution is of the chi-bar-square form. When the exact distribution is unavailable, it may still be possible to find a stochastic ordering of the test statistic, and thereby derive a conservative test. The asymptotic distribution of the test statistic is also studied. Our results do not require that estimates of the k means be independent, provided that their covaria...
TL;DR: In this article, a method for preparing primary cultures of dispersed pituitary cells was described, where cells were dispersed by collagenase 0.1% in Hank's saline solution for 20 hr at 12 degrees and a high yield of viable cells was obtained.
TL;DR: In this paper, the authors show that a major rearrangement of Pb isotopes at about 2600 Ma together with some local third stage Pb changes at a later time is also shown by Rb-Sr data for phengites in the ~3400 Ma Pegmatitic gneiss sheets and can be correlated with metamorphism accompanying the intrusion of a late Archaean pegmatite (~2600 Ma) swarm.
TL;DR: Une population reproductrice du crabe d'eau profonde Chionoecetes opilio migre vers des profondeurs aussi faibles que 5 m dans Bonne Bay, Terre Neuve.
Abstract: Une population reproductrice du crabe d'eau profonde Chionoecetes opilio migre vers des profondeurs aussi faibles que 5 m dans Bonne Bay, Terre Neuve. Les crabes etaient surtout par couple, avec les grands mâles portant les femelles plus petites et habituellement avec des oeufs. Aucune femelle solitaire et independante n'a ete trouvee. Les mâles isoles etaient sexuellement desavantages par la perte d'une pince. Les mâles prenaient la nourriture pour eux-memes et pour la femelle qu'ils portaient. Plus tard ils assistaient les femelles dans la liberation des larves, la mue, occasionnelle, etant suivie de la copulation et de l'emission des oeufs. La competition entre les mâles est severe et il en resulte une perte importante d'appendices, surtout chez les femelles. Mâles et femelles ont des epibiotes significativement differents attaches a leurs teguments, ce qui laisse supposer que les sexes occupent des niches ecologiques separees en dehors de la periode de reproduction.
TL;DR: In this paper, a detailed amino acid epimerization analyses on planktonic foraminifera Neogloboquadrina pachyderma sinistral from a long gravity core was carried out to establish a firm chronology for cores from the Alpha Ridge, Arctic Ocean, and to help resolve the controversy between the ages assigned by different dating methods, supporting previous magnetostratigraphic and micropalaeontological studies.
Abstract: Interpretations of the palaeoclimatic and palaeooceanographic histories of the Arctic Ocean1,2 have been hampered by conflicting chronologies obtained using different dating methods. Magnetostratigraphic and micropalaeontological data1–4 have suggested a sedimentation rate of ∼1 mm kyr−1 whereas the rate indicated by amino acid epimerization analyses on foraminifera5 is an order of magnitude higher. To establish a firm chronology for cores from the Alpha Ridge, Arctic Ocean, and to help resolve the controversy between the ages assigned by different dating methods, we have carried out detailed amino acid epimerization analyses on planktonic foraminifera Neogloboquadrina pachyderma sinistral from a long gravity core. Assuming that the temperature in the Arctic Ocean did not exceed 3°C during the past 1 Myr, the alloisoleucine/isoleucine (alle/Ile) ratios obtained from this core suggest a sedimentation rate of∼1 mm kyr−1, supporting previous magnetostratigraphic and micropalaeontological studies.
TL;DR: Given recent evidence from Asia linking even subclinical vitamin A deficiency to increased risk of mortality and morbidity, this disease is not only a leading cause of blindness in this area, but may have an important impact on child survival as well.
Abstract: The first population-based study of xerophthalmia in Africa was conducted in the Lower Shire River Valley of Malawi in the autumn of 1983. A total of 5,436 children under six years of age were examined by three survey teams over an eight-week period. The prevalence of active xerophthalmia was 3.9%. Rates for night blindness and active corneal disease were more than five times the World Health Organization criterion for a problem of public health importance. Xerophthalmic corneal scarring occurred at a rate of 5.9/1,000, more than 10 times the World Health Organization criterion. All cases of bilateral blindness in this age group were considered to be due to vitamin A deficiency. Given recent evidence from Asia linking even subclinical vitamin A deficiency to increased risk of mortality and morbidity, this disease is not only a leading cause of blindness in this area, but may have an important impact on child survival as well.
TL;DR: The quantities of energy invested in gamete production, somatic tissue growth and synthesis of the organic matrix in the shell were determined for two non-exploited populations of Placopecten magellanicus in Newfoundland.
TL;DR: A total of 100 colposcopic biopsies from patients with abnormal Papanicolau's tests were surveyed for the presence of human papillomavirus (HPV) types 16 and 18 sequences by spot-blot hybridization, suggesting a new type.
TL;DR: The findings support Model 1 over Model 2 for 17/18 predictions that differentiated the models and the status of happiness as a trait was discussed with reference to: the type of items included in the happiness scale; and relationships with variables not included inThe research.
Abstract: The intention of the study was to test between two causal models of relationships between happiness and five of its correlates (i.e., housing satisfaction, financial satisfaction, perceived health, locus of control, and activity level). In Model 1, happiness was identified as a propensity variable that is a source of influence on the lower order correlates. Model 2 is a traditional formulation whereby levels of happiness are determined by its correlates. The models were tested by causal modeling procedures, using 18-month longitudinal data from 408 elderly subjects. The findings support Model 1 over Model 2 for 17/18 predictions that differentiated the models. The status of happiness as a trait was discussed with reference to: (a) the type of items included in the happiness scale; and (b) relationships with variables not included in the research.