Showing papers by "University of Rhode Island published in 1970"
TL;DR: In terms of current knowledge of crustal genesis in the Atlantic Ocean, several unique or highly anomalous features exist in the vicinity of the Azores, such as the seismically active East Azores Fracture Zone extending from Gibraltar to the Mid-Atlantic Ridge, the seismic inactive West Azores fracture Zone which is offset northwards from the trend of the east-west transverse fracture system as mentioned in this paper.
Abstract: Summary
In terms of current knowledge of crustal genesis in the Atlantic Ocean, several unique or highly anomalous features exist in the vicinity of the Azores. These include the seismically active East Azores Fracture Zone extending from Gibraltar to the Mid-Atlantic Ridge; the seismically inactive West Azores Fracture Zone which is offset northwards from the trend of the East Azores Fracture Zone; the transverse island chain of the Azores islands which trends southeast-northwest across the Mid-Atlantic Ridge; the marked change in direction of the Mid-Atlantic Ridge from northeast-southwest to north-south; and the broadening of the Mid-Atlantic Ridge to the east.
Bathymetric and magnetic data from surveys of the Mid-Atlantic Ridge in the Azores area by R.V. Trident, the U.S.Naval Oceanographic Office, and other sources have been compiled. These, together with the previously published data are compatible with a basic model consisting of a Mid-Atlantic Ridge migrating eastwards at the local crustal spreading rate, which is greater to the north than to the south of an east-west transverse fracture system. Superimposed on this is the development of a northwest-southeast trending secondary spreading centre or triple junction, within a ‘leaky transform’ system (Menard & Atwater 1968) which would have developed as the result of a change in the local crustal spreading direction south of the east-west transverse fracture system from mainly east-west to mainly northwest-southeast. Simple geometrical considerations, when combined with the length of a newly proposed ‘Terceira Rift’ and independent estimates of local crustal spreading rates suggest that the change in crustal spreading direction and triple junction development began at least 45 My ago.
153 citations
TL;DR: Pelagic Sargassum was collected in late summer, late winter, and early and late spring from inshore waters, the Gulf Stream and the Sargasso Sea of the Western North Atlantic Ocean as mentioned in this paper.
Abstract: Pelagic Sargassum was collected in late summer, late winter, and early and late spring from inshore waters, the Gulf Stream and the Sargasso Sea of the Western North Atlantic Ocean. The noncolonial macrofauna was picked from the weed samples. The 34 samples contained 67 species and 11,234 individuals. The Shannon-Wiener index of diversity had a mean value of 2.419±0.177 (t.05s
x
−
) and a statistical range between 1.401 and 3.437 (t.05 s). Mean diversity values were not significantly different among the various sampling series, and diversity did not vary with raft volume. High diversity values were related to an equitable distribution of species resulting from a stable environment and an area low in productivity. Species composition of the Sargassum organisms varied seasonally and geographically. Animals were more abundant in the spring than in the fall samples. Samples collected on a transect in the Gulf Stream and Sargasso Sea maintained a similar faunal composition.
90 citations
TL;DR: Model results indicated that the equilibrium assumptions postulated in previous models may be unrealistic, and that local species diversity may indeed increase with predation under some competitive conditions.
87 citations
TL;DR: In this paper, the average velocity of the turbidity currents is 50 and 30 km/hr, respectively, assuming that the most likely single source of the turbulent currents is the Markham River delta at Lae, New Guinea.
Abstract: The western New Britain Trench is receiving abundant sediment from the west. Evidence for earthquake-triggered turbidity currents has been detected in the New Britain Trench through breaks in a submarine telephone cable in 1966 and 1968. The average velocity of the turbidity currents is 50 and 30 km/hr, respectively, assuming that the most likely single source of the turbidity currents is the Markham River delta at Lae, New Guinea. Bottom photographs and sediment samples support these conclusions. Deep-sea channels are present.
86 citations
Abstract: Grazing experiments with freshly caught plankton from Narragansett Bay were performed at weekly or biweekly intervals through most of a seasonal cycle. The laboratory rates (obtained under simulated natural conditions) were multiplied by the zooplankton concentration in the natural environment and the effects of grazing on the phytoplankton community were assessed. Grazing was most extensive in spring and early summer; phytoplankton production was believed to be high and a large standing crop of Skeletonema costatum persisted. The grazing population was severely reduced during summer, but the phytoplankton standing crop did not increase markedly and some other factor must have been limiting primary production at this time. During fall, decreasing light allowed little phytoplankton growth and mild grazing kept the standing crop at a minimum. This grazing ceased in December and with the release in grazing pressure the winter-spring diatom flowering began.
Skeletonema costatum, the dominant bay diatom, was selectively grazed and its longer chains were preferentially removed.
86 citations
TL;DR: It is found that, compared with minimax and LSME designs, the prolate-spheroidal digital filters have very low sidelobes, at the expense of more deviation from a flat passband.
Abstract: The problem of designing a digital low-pass filter is considered from different points of view, including two approaches which have not received sufficient attention. One approach is based on the prolate-spheroidal-function filters of Slepian, Pollak, and Landau. The other is the incompletely specified least mean-square error (LMSE) method which has been proposed by Rorabacher. We find that, compared with minimax and LSME designs, the prolate-spheroidal digital filters have very low sidelobes, at the expense of more deviation from a flat passband. If a transition band or "don't care" region of the frequency response is assumed, then the results of the minimax and LSME methods are nearly the same.
84 citations
TL;DR: Using radioactive tags, movements of salamanders (Plethodon jordani) in their home areas and during homing are recorded to give direct evidence of homing orientation in caudate amphibians.
Abstract: Using radioactive tags, we recorded movements of salamanders (Plethodon jordani) in their home areas and during homing. Males occupied home areas about three times larger than those of females and made occasional excursions into outlying regions. Homing after 22-to 60-meter displacements was direct and rapid, once initiated. Course headings at 1 meter from release were random; those at 2 meters and more were home-oriented. Males initiated homing movements sooner than females, although both sexes traveled at similar rates. Increased incidence of climbing on vegetation after displacement suggests olfactory mechanisms of orientation. These observations give direct evidence of homing orientation in caudate amphibians.
77 citations
TL;DR: During a poor year for Calanus finmarchicus in Rhode Island Sound, the fatty acids vary independently of each other, in agreement with previous findings for free amino acids.
Abstract: Fatty acid composition of the plankton in Narragansett Bay, Rhode Island, varies in relation to the seasonal succession and productivity of populations. The ratio of palmitoleic acid to palmitic acid declines during vernal warming from 2.0 to ca. 0.3, reflecting the change in dominance from diatoms to flagellates. In the zooplankton, the ratio is twice as high in Acartia clausi, the winter dominant copepod, as in the summer species, Acartia tonsa.
Palmitoleic acid and palmitic acid vary reciprocally throughout the year; so do oleic and stearidonic acids. If palmitic and oleic acids, the less saturated members of each covariate pair, arc related by multiple linear regression to zooplankton standing crop, 52% of the variation over an annual cycle is explained.
During a poor year for Calanus finmarchicus in Rhode Island Sound, the fatty acids vary independently of each other, in agreement with previous findings for free amino acids.
74 citations
TL;DR: It is considered that phylloquinone oxide, because of structural similarity, may be an inhibitor of phyllaquinone and that warfarin exerts its anticoagulant effect by causing accumulation of the oxide.
73 citations
TL;DR: Study of 18 Cenozoic South Pacific deep-sea cores indicates an association of glacially derived ice-rafted sands and relatively low planktonic foraminiferal diversity with cooling of the Southern Ocean during the Lower Eocene, upper MiddleEocene, and Oligocene.
Abstract: Study of 18 Cenozoic South Pacific deep-sea cores indicates an association of glacially derived ice-rafted sands and relatively low planktonic foraminiferal diversity with cooling of the Southern Ocean during the Lower Eocene, upper Middle Eocene, and Oligocene. Increased species diversity and reduction or absence of ice-rafted sands in Lower and Middle Miocene cores indicate a warming trend that ended in the Upper Miocene. Antarctic continental glaciation appears to have prevailed throughout much of the Cenozoic.
70 citations
TL;DR: Increase in proline hydroxylase activity may be a possible biochemical defect in the aortas of rabbits with arteriosclerosis induced by injury.
Abstract: The relation of collagen synthesis to experimentally induced arteriosclerosis was studied by measuring proline hydroxylase activity. Gross aortic plaques were produced in rabbits by daily injection of epinephrine (intravenous) and thyroxine (intraperitoneal) for 4, 9, or 14 days. Activity of proline hydroxylase was significantly increased after 4 days of treatment and reached a peak, five- to sixfold increase, after 14 days of treatment. The increase in enzyme activity was correlated with the severity of observed arteriosclerosis. Increase in proline hydroxylase activity may be a possible biochemical defect in the aortas of rabbits with arteriosclerosis induced by injury.
TL;DR: In this paper, a four-parameter rigid ion model utilizing an effective ionic charge was used for the determination of phonon dispersion, phonon density of states, and the Debye characteristic temperature of ZnTe.
Abstract: A four-parameter rigid-ion model utilizing an effective ionic charge is used for the determination of phonon dispersion, phonon density of states, and the Debye characteristic temperature of ZnTe. Structures in the infrared spectrum of ZnTe are assigned to multiphonon combinations of various critical-point phonon frequencies. Using the long-wavelength optic-mode phonon frequencies as well as the elastic constants and their respective pressure derivatives as input data, the mode Gr\"uneisen parameters, the Gr\"uneisen constant, and the coefficient of thermal expansion of ZnTe are calculated.
TL;DR: Studies of deep-sea sedimentary cores from Antarctic Pacific waters show that some volcanic maxima occurred when the geomagnetic polarity was changing, and these incidents may be explained by corresponding volcanically induced climatic changes.
Abstract: Studies of deep-sea sedimentary cores from Antarctic Pacific waters show that some volcanic maxima occurred when the geomagnetic polarity was changing. Upper mantle activity and geomagnetic polarity change may therefore be related. Coincidences of faunal extinction and geomagnetic polarity change may be explained by corresponding volcanically induced climatic changes.
TL;DR: Pour le stimulant acoustique entre 10 et 150 Hz les seuils de réponses ont été obtenus sur 5 homards (Homarus americanus) pour obtenir en bradycardie un si haut seuil tonal de stimulation.
Abstract: Pour le stimulant acoustique entre 10 et 150 Hz les seuils de reponses ont ete obtenus sur 5 homards (Homarus americanus). La plus grande sensibilite etait de 37,5 Hz pour une pression de — 13 db re: 1 bar, ou bien de 75 Hz pour une rapidite de particules de 19 db re: 1 var, conditions classiques realisees pour obtenir en bradycardie un si haut seuil tonal de stimulation.
TL;DR: In this paper, the authors measured the temperature dependences between 2° and 25°C of stoichiometric association constants of NaSO4− and MgSO4° ion-pairs by a potentiometric procedure.
TL;DR: The therapeutic indexes of duration of action and the period of time involved between administration of the drug and the time when the activity is first manifested increased as the relative polarity of these barbiturates declined.
TL;DR: The cell of Pyrocystis spp.
Abstract: SUMMARY
The cell of Pyrocystis spp. is covered by an outer layer of material resistant to strong acids and bases. Internal to this layer much of the cell wall is composed of cellulose fibrils. The presence of cellulose fibrils was established by staining raw and ultra-violet–peroxide-cleaned cell walls and by combining X-ray diffraction spectroscopy with electron microscope observation. Carbon replicas of freeze-etched preparations and thin sections of P. lunula walls show outer layers, inside them ca. 24 layers of crossed parallel cellulose fibrils (4–5 nm thick, ca. 12 nm wide), then a region of smaller (ca. 6–12 nm diameter) fibrils in a disperse texture, and then the plasma membrane. Cellulose fibrils in the parallel texture are constructed of 3–5 elementary fibrils ca. 3 nm in diameter. Walls of P. fusiformis and P. pseudonctiluca also have cellulose fibrils in a crossed parallel texture similar to those of P. lunula.
The Gymnodinium-type swarmer from lunate P. lunula appears to have a cell wall ultrastructure typical of other “naked” dinoflagellates.
TL;DR: The influence of 113 combinations of temperature, salinity, and light on the mean daily cell division rate of the Narragansett Bay clone of Rhizosolenia fragilissima was examined following appropriate preconditioning.
Abstract: SUMMARY
The influence of 113 combinations of temperature (9, 12, 18, 25, 30 C), salinity (5–35 ‰ at 5 ‰ intervals), and light (4 levels) on the mean daily cell division rate (K) of the Narragansett Bay clone of Rhizosolenia fragilissima was examined following appropriate preconditioning. Growth did not occur below 9 C, but was excellent (K =∼1.2) under certain combinations of light and salinity at 12, 18, and 25 C. The optimal salinity of 20–25 ‰ was temperature independent. Growth was not measurable at 5 ‰, although survival occurred. At 20 ‰ and 1200 ft-c, K increased approximately 1.8-fold from 0.65 to ∼1.2 between 9 and 18–25 C.
The optimal light intensity was generally 600 ft-c, although several light-temperature-salinity trends were found. At 10 ‰ at all temperatures, the mean daily division rate decreased with increasing light above 600 ft-c, a response found at all salinities at 12 C, but not at other temperatures. Between 15 and 25 ‰, at 18 and 25 C, mean growth was independent of light intensity; at 30–35 ‰ a direct relationship with light may be present with maximum growth occurring at 1200–1800 ft-c.
The in situ and in vitro responses of Rhiz. fragilissima to salinity and the optimum and upper temperature levels are in general agreement. However, growth failure below 9 C in vitro is at odds with reports that natural populations occur even at −1.11 C. The questions of to what extent this discrepancy reflects the occurrence of thermal clones, different taxa, and/or experimental artifacts are briefly discussed. It is suggested that naturally occurring populations found below 9 C might be designated as Rhiz. fragilissima f. faeroensis, and that Rhiz. fragilissima f. bergonii be used for populations growing at higher temperatures, until this matter is resolved.
Observations on auxospore formation are presented.
TL;DR: It is shown that useful performance can be achieved within the constraints of very simple realizations in a class of narrow-band digital filters.
Abstract: Models for a class of narrow-band digital filters and a class of wide-band digital filters are developed and analyzed The analysis forms a basis for a computer-aided design technique for such filters. Our aim is to show that useful performance can be achieved within the constraints of very simple realizations.
TL;DR: The possibility that induction of drug-metabolizing enzymes by phenobarbital may be mediated in part through suppression of enzymes capable of degrading RNA is suggested.
TL;DR: The developmental pattern, subcellular distribution and general properties of UDP-galactose: N - acetylgalactosaminyl-( N -acetylneuraminyl)-galactsosyl-glycosyl-ceramide galactosyltransferase (UDP-Galactose) in rat brain is described and a sharp peak of enzyme activity occurred during the period of active myelination.
TL;DR: In this paper, the phonon dispersion curves for CsCl, CsBr, and CsI have been obtained using a rigid-ion model with an appropriate effective ionic charge.
Abstract: The phonon dispersion curves for CsCl, CsBr, and CsI have been obtained using a rigid-ion model with an appropriate effective ionic charge. The five model parameters for each crystal are obtained from three elastic constants and the two long-wavelength optic-mode frequencies, reliable data for which exist for all three crystals. Our results are in agreement with those of more elaborate models. The phonon density of states and the Debye characteristic temperatures are also calculated. A Born-Mayer-type potential is used to calculate long-wavelength LO and TO mode frequencies as functions of pressure from pressure dependence of bulk modulus. The result for TO of CsBr agrees well with a recent experimental determination. Next, using the values of the elastic constants and LO and TO frequencies at various pressures, $\ensuremath{\omega}\ensuremath{-}\mathrm{v}\mathrm{e}\mathrm{r}\mathrm{s}\mathrm{u}\mathrm{s}\ensuremath{-}\stackrel{\ensuremath{\rightarrow}}{\mathrm{k}}$ curves in selected directions are generated as functions of pressure. Mode Gr\"uneisen parameters are then calculated as functions of $\stackrel{\ensuremath{\rightarrow}}{\mathrm{k}}$. Finally, the Gr\"uneisen constant and the volume coefficient of thermal expansion are obtained as functions of temperature. They agree very well with available experimental data.
TL;DR: The design of a practical controller for a plant representative of a telescope primary mirror for an orbiting astronomical observatory is presented and a quadratic performance index which incorporates a measure of image quality permits determination of the trade-off between the number of actuators and optical purity.
TL;DR: A variety of geomorphic features occur on the continental shelf from Portuguese Guinea to Sierra Leone as mentioned in this paper, including barrier spits, barrier island-lagoon complexes, and sea cliffs at −90, −80, −55, −45, −35, and −25m levels.
TL;DR: Tryptamine is more effective than 5-hydroxytryptamine in potentiating twitches and in inducing rhythmicity, and at comparable concentrations, tryptamine ismore effective in relaxing acetylcholine contracture.
TL;DR: Going from a marine species, through a series of three estuarine species, and finally to a fresh water representative, the basic amino acids become more important, whereas glycine, alanine and taurine decrease, resulting in a comparatively uniform pattern of composition in fresh water.
TL;DR: In this article, the modified random element isodisplacement model correctly predicts that a two-mode-type mixed crystal forms a "two-mode" mixed crystal, and the model calculations agree very well with a recent infrared measurement of concentration dependence of long-wavelength longitudinal and transverse optic mode frequencies of the mixed-crystal system.
Abstract: The modified random-element isodisplacement model correctly predicts that ${\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{Al}}_{x}\mathrm{As}$ forms a "two-mode"-type mixed crystal. The model calculations agree very well with a recent infrared measurement of concentration dependence of long-wavelength longitudinal and transverse optic mode frequencies of the mixed-crystal system.
TL;DR: The 50S and 30S ribosomes and 23S and 16S RNA were hydrolyzed with ribonuclease A and the rate constants and number of fragments produced were determined for each reaction.
Abstract: The 50S and 30S ribosomes and 23S and 16S RNA were hydrolyzed with ribonuclease A. The rate constants and number of fragments produced were determined for each reaction. The conformation of 23S RNA changes when the RNA is extracted from the ribosome. Specific regions of the RNA in 50S and 30S ribosomes are protected from hydrolysis by the ribosomal proteins.
TL;DR: The larvae ofC.
Abstract: 1. Larvae ofCancer irroratus were raised in the laboratory from the first zoeal stage to the first crab stage. Five zoeal stages and one megalops stage were observed during development to the first crab stage. 2. The larvae developed to the megalops stage in salinities of 20 ‰, 25 ‰, 30 ‰ and 35 ‰, and at temperatures of 10°, 15° and 20° C. The megalops metamorphosed in all the four salinities at 15° C, and in 25 ‰ at 20° C. A temperature-salinity combination of 15° C and 30 ‰ S was found to allow maximum survival of larvae until the crab stage. The different salinities do not seem to affect greatly the duration for zoeal development, megalops development and total development to the crab stage at 15° C. 3. The larvae ofPanopeus herbstii were also raised to the first crab stage in the laboratory at 20° and 25° C and 32 ‰ S. There were four zoeal stages and one megalop stage during complete development in the laboratory. 4. A re-circulating sea water system has been designed and fabricated for cultivation of crab larvae under controlled environmental conditions in the laboratory. The larvae ofC. irroratus andP. herbstii, cultured in the sea water system, completed their development to the first crab stage.