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Showing papers by "University of Rhode Island published in 1991"


Journal ArticleDOI
TL;DR: This study tested the transtheoretical model of change that posits a series of stages through which smokers move as they successfully change the smoking habit, and results strongly support the stages of change model.
Abstract: Traditionally smoking cessation studies use smoker and nonsmoker categories almost exclusively to represent individuals quitting smoking. This study tested the transtheoretical model of change that posits a series of stages through which smokers move as they successfully change the smoking habit. Subjects in precontemplation (n = 166), contemplation (n = 794), and preparation (n = 506) stages of change were compared on smoking history, 10 processes of change, pretest self-efficacy, and decisional balance, as well as 1-month and 6-month cessation activity. Results strongly support the stages of change model. All groups were similar on smoking history but differed dramatically on current cessation activity. Stage differences predicted attempts to quit smoking and cessation success at 1- and 6-month follow-up. Implications for recruitment, intervention, and research are discussed.

2,360 citations


Journal ArticleDOI
TL;DR: The atmospheric transport of continental weathering products is responsible for much of the mineral material and Fe entering the open ocean and is probably the dominant source of nutrient Fe in the photic zone as discussed by the authors.
Abstract: The atmospheric transport of continental weathering products is responsible for much of the mineral material and Fe entering the open ocean and is probably the dominant source of nutrient Fe in the photic zone. In regions where other nutrients are present in high concentrations, the flux of Fe from the atmosphere may be a limiting factor in primary productivity. Due to the larger source regions for dust north of the equator, ∼8 times more atmospheric Fe is deposited in the northern hemisphere than in the southern hemisphere. The mineral aerosol and Fe transport and deposition are highly variable due to the episodic nature of dust generation and its transport and deposition processes. Between 10 and 50% of the total atmospheric Fe entering the world ocean appears to dissolve (i.e. it will pass through a 0.4-µm pore-size filter) rapidly when the mineral matter enters the ocean. Much of the atmospheric Fe is present as Fe(II), apparently produced as a result of photochemical reduction reactions taking place during atmospheric transport. This readily soluble Fe(II) should be available immediately for use as a nutrient by phytoplankton. Atmospheric transport from the continents is estimated to supply ∼3 times as much dissolved Fe to the oceans as that delivered via rivers.

997 citations


Journal ArticleDOI
01 Jun 1991-Geology
TL;DR: For the past 150 m.y. as mentioned in this paper, a 50% to 75% increase in ocean crust formation rate between 120 and 80 Ma was seen both in spreading-rate increases from ocean ridges and in the age distribution of oceanic plateaus.
Abstract: A calculation of Earth's ocean crustal budget for the past 150 m.y. reveals a 50% to 75% increase in ocean crust formation rate between 120 and 80 Ma. This "pulse" in ocean crust production is seen both in spreading-rate increases from ocean ridges and in the age distribution of oceanic plateaus. It is primarily a Pacific Ocean phenomenon with an abrupt onset, and peak production rates occurred between 120 and 100 Ma. The pulse decreased in intensity from 100 to 80 Ma, and at 80 Ma rates dropped significantly. There was a continued decrease from 80 to 30 Ma with a secondary peak near the Cretaceous/Tertiary boundary at 65 Ma. For the past 30 m.y., ocean crust has formed at a nearly steady rate. Because the pulse is seen primarily in Pacific oceanic plateau and ridge production, and coincides with the long Cretaceous interval of normal magnetic polarity, I interpret it as a "superplume" that originated at about 125 Ma near the core/mantle boundary, rose by convection through the entire mantle, and erupted beneath the mid-Cretaceous Pacific basin. The present-day South Pacific "superswell" under Tahiti is probably the nearly exhausted remnant of the original upwelling. How this superplume stopped magnetic field reversals for 41 m.y. is a matter of speculation, but it probably involved significant alteration of the temperature structure at the core/mantle boundary and the convective behavior of the outer core.

863 citations


Journal ArticleDOI
TL;DR: This study developed and validated the Weight Efficacy Life-Style Questionnaire (WEL), improving on previous studies by the use of clinical populations, cross-validation of the initial factor analysis, exploration of the best fitting theoretical model of self-efficacy, and examination of change in treatment.
Abstract: Self-efficacy is an important mediating mechanism in advancing understanding of the treatment of obesity. This study developed and validated the Weight Efficacy Life-Style Questionnaire (WEL), improving on previous studies by the use of clinical populations, cross-validation of the initial factor analysis, exploration of the best fitting theoretical model of self-efficacy, and examination of change in treatment. The resulting 20-item WEL consists of five situational factors: Negative Emotions, Availability, Social Pressure, Physical Discomfort, and Positive Activities. A hierarchical model was found to provide the best fit to the data. Results from two separate clinical treatment studies (total N = 382) show that the WEL is sensitive to changes in global scores as well as to a subset of the five situational factor scores. Treatment programs may be incomplete if they change only a subset of the situational dimensions of self-efficacy. Theoretical and clinical implications are discussed.

624 citations


Journal ArticleDOI
01 Oct 1991-Geology
TL;DR: Superplumes are suggested to have caused the period of constant normal magnetic polarity in mid-Cretaceous time (124-83 Ma) and, possibly, the time of constant reversed polarity (323-248 Ma) in Pennsylvania-Permian time as discussed by the authors.
Abstract: Superplumes are suggested to have caused the period of constant normal magnetic polarity in mid-Cretaceous time (124-83 Ma) and, possibly, the period of constant reversed polarity in Pennsylvania-Permian time (323-248 Ma). These times coincide with increases in world temperature, deposition of black shales, oil generation, and eustatic sea level in the mid-Cretaceous, and increased coal generation and gas accumulation in the Pennsylvanian-Permian, accompanied by an intracratonic Pennsylvanian transgression of epicontinental seas. These geologic anomalies are associated with episodes of increased world-wide ocean-crust production and mantle outgassing, especially of carbon and nutrients. These superplumes originated just above the core-mantle boundary, significantly increased convection in the outer core, and stopped the magnetic field reversal process for 41 m.y. in the Cretaceous and 75 m.y. in Pennsylvanian-Permian time.

592 citations


Journal ArticleDOI
TL;DR: This relationship is robust since it applies to preschool-, elementary school-, and high school-age children, to both boys and girls, and to children who were also physically punished as well as those who were not.

424 citations


Journal ArticleDOI
01 Aug 1991-Nature
TL;DR: The behavior of thermal plumes in the Earth's upper mantle is strongly affected by their interaction with nearby mid-ocean ridges, and the magnitude of the buoyant topography and the length of the geochemical anomaly induced by plumes at migrating ridge axes provide a way to estimate their excess temperature and discharge rate, and thereby constrain their depth of origin this paper.
Abstract: The behaviour of thermal plumes in the Earth's upper mantle is strongly affected by their interaction with nearby mid-ocean ridges. The magnitude of the buoyant topography and the length of the geochemical anomaly induced by plumes at migrating ridge axes provide a way to estimate their excess temperature and discharge rate, and thereby constrain their depth of origin.

389 citations


Journal ArticleDOI
TL;DR: The use of a stage-matched, patient-centered counseling intervention can help physicians to feel less frustrated and more effective in their efforts to help a broad range of their patients.

314 citations



Journal ArticleDOI
01 May 1991-Nature
TL;DR: It is reported that an oceanic diatom was able to grow at a near maximum specific rate of about 1.0 per day at a cellular Fe:C ratio of 2 μmol: mol, about 25% of the amount needed for the same rate in a related estuarine species, and 2–20% of values previously used to estimate algal Fe requirements in sea water.
Abstract: DESPITE the controversy on the importance of iron in limiting phytoplankton growth and affecting air–sea exchange of CO2 in the ocean1–4, there is very little information on cellular iron requirements for growth. The few data available5,6 come from species isolated from coastal sea water where dissolved Fe levels are 10–1,000 times higher than those (≤0.1 nM) in the open ocean1,7. Species from oceanic waters require much lower external Fe concentrations for growth than do comparable coastal species8. Here we report that an oceanic diatom was able to grow at a near maximum specific rate of about 1.0 per day at a cellular Fe:C ratio of 2 μmol: mol, about 25% of the amount needed for the same rate in a related estuarine species, and 2–20% of values previously used to estimate algal Fe requirements in sea water1,2. These results have important implications concerning iron limitation of primary productivity in the ocean and cell biology of iron in oceanic algae.

281 citations


Journal ArticleDOI
TL;DR: In this article, the authors suggest that mantle plumes control magnetic reversal frequency by the following sequence of events, which increases core cooling by allowing heat to be conducted more rapidly across the core/mantle boundary.

Journal ArticleDOI
TL;DR: It is proposed that planktonic Protozoa constitute a high quality, nitrogen-rich food in the diets of their metazoan consumers and implications of die trophic link to the consumers, prey, and ecosystem are discussed.
Abstract: The evidence for a qualitatively and quantitatively important trophic link between planktonic Protozoa and higher order metazoan consumers is reviewed. the available data are obtained primarily, but not exclusively, from laboratory studies of calanoid copepod consumers and tintinnid ciliate prey from marine estuarine and nearshore environments. the data indicates that the protozoan-metazoan link is of similar magnitude and importance in the pelagic ecosystems of freshwaters. It is proposed that planktonic Protozoa constitute a high quality, nitrogen-rich food in the diets of their metazoan consumers. Implications of die trophic link to the consumers, prey, and ecosystem are discussed.

Journal ArticleDOI
TL;DR: In this article, a cued reaction-time test was used to assess covert and overt shifts of attention theoretically linked to two neuroanatomically defined attentional systems in the posterior and anterior parts of the human brain.
Abstract: The clinical label attention deficit hyperactivity disorder (ADHD) suggests that this syndrome is a disorder of attention. However, the presumed attentional deficits have not been linked either to specific cognitive operations or to specific neural systems. To provide this link, theories of the cognitive anatomy of attention were used to generate hypotheses about specific visual-spatial attentional deficits in children with ADHD. A cued reaction-time test was used to assess covert and overt shifts of attention theoretically linked to two neuroanatomically defined attentional systems in the posterior and anterior parts of the human brain. The early, posterior-based covert shift of attention was found to be normal in ADHD children, but a later, anterior-based overt shift of attention was abnormal as reflected by a significant lateral difference in reaction time. This was interpreted as a failure to sustain focused attention.

Journal ArticleDOI
TL;DR: The data suggest that older adults experience greater muscle damage following eccentric exercise than young subjects, which may be due in part to the smaller muscle mass and lower VO2max seen in older men.
Abstract: Plasma creatine kinase (CK) activity has often been used as a marker of exercise-induced skeletal muscle damage. While the pattern of muscle damage following eccentric exercise has been established in young adults, there is little data available on eccentric exercise-induced muscle damage in

Journal ArticleDOI
TL;DR: In this paper, a method was developed for the selective enumeration of F male-specific bacteriophages in samples of environmental waters, and the F malespecific phage levels in prechlorinated, secondary-treated sewage effluents generally were about 10(3) to 10(4) PFU/100 ml.
Abstract: A method was developed for the selective enumeration of F male-specific bacteriophages in samples of environmental waters. The host strain for the phages, Escherichia coli HS(pFamp)R, has three antibiotic resistance markers, ampicillin on the Famp plasmid, which codes for pilus production, and streptomycin and nalidixic acid on the chromosome. The strain is resistant to coliphages T2 to T7 and phi X174. More than 95% of the phages from environmental samples which plaqued on the host strain were F male specific. The host bacterium had a higher plaquing efficiency than E. coli K-12 Hfr for F-specific phages in stock suspensions and sewage effluents. The F male-specific phage levels in prechlorinated, secondary-treated sewage effluents generally were about 10(3) to 10(4) PFU/100 ml. The levels in the influents to the sewage treatment plants and in septic tank contents were about 10(5) PFU/100 ml. RNA-containing phages composed about 90% of the total F-specific phage population in sewage effluents.

Journal ArticleDOI
07 Feb 1991-Nature
TL;DR: Tektite-like glasses preserved at the Cretaceous/Tertiary boundary at Beloc in Haiti provide clear evidence of an impact event as mentioned in this paper. But they do not provide evidence of a catastrophic release of C02 from vaporized marl during the impact.
Abstract: Tektite-like glasses preserved at the Cretaceous/Tertiary boundary at Beloc in Haiti provide clear evidence of an impact event. The glass composition suggests that the impact occurred on a continental shelf region, generating a silica-rich glass with chemical composition that reflects the melting of continental crustal rocks, and a calcium-rich glass produced by the fusion of marl sediments. These findings indicate that catastrophic release to the atmosphere of 1015 moles of C02 from vaporized marl occurred during the impact.

Journal ArticleDOI
TL;DR: In this paper, a hierarchy of four orders of ridge axis discontinuities based on a continuum of relative age and distance offset across the discontinuites is proposed, where rigid offsets represent rigid offsets, transform faults, whereas non-rigid discontinuity fall into the second, third and fourth orders.
Abstract: Continuous along-axis Sea Beam coverage of the slow-intermediate spreading (34–38 mm yr−1 full rate) southern Mid-Atlantic Ridge (25°–27°30′S and 31°–38° S) shows that the ridge axis is segmented by both rigid and non-rigid discontinuities. Following the model of Macdonald et al. (1988b), a hierarchy of four orders is proposed for ridge axis discontinuities based on a continuum of relative age and distance offset across the discontinuites. This paper discusses the characteristics associated with five second-order discontinuities found in the areas surveyed. First-order discontinuities represent rigid offsets, transform faults, whereas non-rigid discontinuities fall into the second, third and fourth orders. Like transform fault boundaries, second-order discontinuities have distinctive morphologic signatures both on and off-axis-discordant zones — and therefore are better defined than third- or fourth-order discontinuities. Second-order discontinuities are offsets that range in distance from less than 10 km to approximately 30 km and vary in age offset from 0.5 to approximately 2.0 m.y. The variable morphotectonic geometries associated with these discontinuities indicate that horizontal shear strains are accommodated by both extensional and strike-slip tectonism and that the geometries are unstable in time. Three characteristic geometries are recognized: (1)en echelon jog in the plate boundary where ridge axis tips overlap slightly, (2)en echelon jog in the plate boundary where ridge axes are separated by an extensional basin whose long axis is oriented parallel to the strike of the adjoining ridge axes, and (3) oblique offset characterized by a large extensional basin that is oriented approximately 45° to the strike of the ridge axes. In the case of the third type, evidence for short strands of strike-slip tectonism that link an obliquely oriented extensional basin flanking ridge tips is often apparent. Analysis of the detailed bathymetric and magnetic data collected over the second-order discontinuities and their off axis terrain out to 5–7 m.y. documents that second-order discontinuities can follow several evolutionary paths: they can evolve from transform fault boundaries through prolonged asymmetric spreading, they may migrate along strike leaving a V-shaped wake, and they may remain in approximately the same position but oscillate slightly back and forth. In addition, a small change in the pole of relative motion occurring 4–5 Ma is thought to have resulted in the initiation of at least one second-order discontinuity in the survey area. A geologic model is proposed which involves the interplay of lithospheric thickness, asymmetric spreading, temporal and spatial variability of along-axis magmatic input and changes in the poles of relative motion to explain the origin, morphology and evolution of second-order ridge axis discontinuities.

Journal ArticleDOI
TL;DR: The authors argued that comprehension is not just about understanding words, sentences, or even texts, but involves building a model within the mind of the comprehender, which is a complex process that occurs with few external signs along the way.
Abstract: complex process that occurs with few external signs along the way. Out of recent research has come a growing understanding that comprehension is not just understanding words, sentences, or even texts, but involves building a model within the mind of the comprehender. In the past, comprehension research has been widely influenced by the generative-transformational theory of language, which described comprehension as building meaning from the smallest, simplest sentence-level features. This view predominated for some time despite some evidence to the contrary. For example, in 1932 Bartlett objected to research that used simplified stimuli such as nonsense words to test the

Journal ArticleDOI
TL;DR: Kinetic analysis showed that verapamil decreased the Vmax of cadmium uptake, without altering the Km, indicating a noncompetitive inhibition, and data suggest that about a third of the Cadmium enters hepatocytes through the calcium channels.

Journal ArticleDOI
TL;DR: In this article, the 14°N mantle source is shown to be a mixture of Walvis-like and HIMU-like materials and the geochimical observations support the model of an incipient ridge-centered plume.

Journal ArticleDOI
01 Feb 1991-Cancer
TL;DR: Stage measures provide differential predictions for the amount of progress people in different stages will make after treatment and can help to explain the dynamics of behavior change.
Abstract: Traditional assessments of behavior change relied on discrete measures based on assumptions that changes occur quickly, dichotomously, and without relapse. People were expected to shift dramatically from smokers to nonsmokers or from unhealthy to healthy lifestyles. A stage model of change has greater potential to assess the dynamics of change with some people progressing linearly from contemplation to maintenance, others relapsing back to contemplation, and others remaining in a stage like contemplation for long periods. Stage measures provide differential predictions for the amount of progress people in different stages will make after treatment. Assessing processes of change that people apply to progress from one stage to the next can also help to explain the dynamics of behavior change.

Journal ArticleDOI
01 Jan 1991
TL;DR: The sedimentary history was most visibly affected by the coccolithophorid species Emiliania huxleyi which briefly invaded the Black Sea for the first time (First Invasion Period) and nearly disappeared again shortly afterwards (Transition Sapropel) but returned permanently several centuries later (Final Invasion Period).
Abstract: The temporal sedimentary patterns in the Late Holocene central eastern and western Black Sea are very similar. The sedimentary history was most visibly affected by the coccolithophorid species Emiliania huxleyi which briefly invaded the Black Sea for the first time (“First Invasion Period”), nearly disappeared again shortly afterwards (“Transition Sapropel”), but returned permanently several centuries later (“Final Invasion Period”). The temporary near-disappearance of E. huxleyi was probably caused by a temporary drop in salinity. Accumulation of E. huxleyi was on average about 40% higher in the western than in the eastern Black Sea. Highest coccolithophorid production occurred basin-wide during part of the Little Ice Age. The accumulation of terrigenous matter was generally higher in the eastern than in the western Black Sea by about 20%.

Journal ArticleDOI
TL;DR: In this article, a model for sedimentation from radially spreading gravity currents generated at the top of ascending sediment-laden plumes is described by a model which assumes that sediment is dispersed homogeneously by turbulence in the gravity current, resulting in an exponential decrease in the concentration of sediment with time as particles settle out of the lower boundary of the current.
Abstract: Sedimentation from radially spreading gravity currents generated at the top of ascending sediment-laden plumes is described by a model which assumes that sediment is dispersed homogeneously by turbulence in the gravity current, resulting in an exponential decrease in the concentration of sediment with time as particles settle out of the lower boundary of the current. For radial spreading this model predicts a Gaussian distribution of sediment accumulation away from the source with an exponential constant, B, which depends on flow rate, Q, and particle settling velocity, v (B=nv/Q). In the experiments described, sedimentation occurs from gravity currents generated by ascent of buoyant, particle-laden plumes of fresh water in a tank of salty water. The sediment accumulation shows close agreement with the theoretical model, and the Gaussian decay constant, B, can be determined from a maximum in the accumulated mass of sediment per unit distance and from the slope of the line In(S/S0) = -Br2, where r is the radial distance, S is the sediment mass flux per unit area and S0 is the value of S at r=0. Data from the dispersal of volcanic ejecta from a large (c. 24 km high) plinian eruption column in the Azores also show good agreement with the theory, confirming that it is general and independent of scale and the nature of the fluid. The experimental data also show a change in sedimentation behaviour at distances from the source corresponding to the corner of the plume where it diverts into a lateral gravity current and there is an abrupt decrease in vertical velocity. Sedimentation of coarse grain sizes, between the source and the corner, occurs from the inclined plume margins and does not behave as predicted by the theoretical model.

Journal ArticleDOI
TL;DR: In this article, the molar absorptivity of the Fe(II)-ferrozine complex in methanol was 28.1 × 103 l mol−1 cm−1 at 562 nm.

Journal ArticleDOI
TL;DR: In this paper, an analytical study is conducted to determine the thermal response of a widely used ablative glass-filled polymer composite, which does not include the idealized assumption of local-thermal equilibrium existing between the solid matrix and decomposition gases within the tortuous pore network of the material.

Journal ArticleDOI
01 Oct 1991-Nature
TL;DR: In this paper, a trace-element and stable and radiogenic isotope data were used to show that the Haiti glass is derived from continental crust of andesitic composition, whereas the high-Ca glass formed by melting of evaporite-rich sediment.
Abstract: THE 50-cm-thick Cretaceous/Tertiary boundary layer at Beloc in Haiti contains spherules of silicic black glass, 1–8 mm in diameter, which have been attributed to impact fusion of continental crust1. Calcic yellow glass (up to 30 wt% CaO) forms a coating on and streaks within some black glass spherules, and has been attributed to melting of carbonate-rich sediment1, or organic-rich or pyritic limestone2. Here we present new trace-element and stable and radiogenic isotope data which show that the silicic glass is derived from continental crust of andesitic composition, whereas the high-Ca glass formed by melting of evaporite-rich sediment. This is confirmed by melting experiments with evaporite and andesite at 1,200–1,400 °C, which approximately reproduce the high-Ca glass. The temperature-dependent variation of sulphur content in synthetic high-Ca glasses indicates a formation temperature of 1,300 °C for the Haiti glasses. The geology of the impact site inferred from the geochemistry of the Haiti glasses matches the lithologies found in the 180-km Chicxulub structure, which occurs in Cretaceous evaporite deposits in Mexico. The high sulphur content of the calcic glasses suggests that the impact may have generated significant emissions of sulphur dioxide to the atmosphere, causing short-term global cooling.

Journal ArticleDOI
TL;DR: A unified statistical performance analysis using perturbation expansions is applied to subspace-based algorithms for direction-of-arrival (DOA) estimation in array signal processing using the MUSIC, Min-Norm, State-Space Realization, and ESPRIT algorithms.

Journal ArticleDOI
TL;DR: In vitro findings suggest that the step of acyl-CoA formation assume a pivotal role in controlling the stereoselectivity and efficiency of the in vivo metabolism of ibuprofen isomerization in guinea pigs.

Journal ArticleDOI
TL;DR: The proposed model provided the most parsimonious fit and explained 29% of the variance in SE and provides preliminary validity for model use in examining the manner in which exercise experiences influence levels of self-perception.
Abstract: This study tested structural relationships within a model proposed to explain the manner in which self-esteem changes are associated with exercise experiences. As initially assessed by self-efficacies (EFFs) specific to physical tasks within a training program, we postulated that competence can generalize to feelings of global self-esteem (SE) through an intervening construct of perceived physical competence (PC). Three measures of EFF and two each of PC and SE were administered to 145 people in their mid- to late adulthood. Confirmatory factor analysis examined orthogonal and oblique versions of three measurement models and identified three distinct but correlated factors, each assessed by its hypothesized indicators. Alternative structural equation models were specified and tested using both normal and nonnormal estimation procedures. The proposed model provided the most parsimonious fit and explained 29% of the variance in SE. Confirmation of its structural relationships provides preliminary validity for model use in examining the manner in which exercise experiences influence levels of self-perception.

Journal ArticleDOI
08 Nov 1991-Science
TL;DR: Results of a three-year field study of family-level patterns of ecological diversity of dinosaurs in the Hell Creek Formation show no evidence of a gradual decline of dinosaurs at the end of the Cretaceous, in agreement with an abrupt extinction event such as one caused by an asteroid impact.
Abstract: Results of a three-year field study of family-level patterns of ecological diversity of dinosaurs in the Hell Creek Formation of Montana and North Dakota show no evidence (probability P