Showing papers by "University of Rhode Island published in 2003"

Developmental Trajectories of Childhood Disruptive Behaviors and Adolescent Delinquency: A Six-Site, Cross-National Study

Abstract: This study used data from 6 sites and 3 countries to examine the developmental course of physical aggression in childhood and to analyze its linkage to violent and nonviolent offending outcomes in adolescence The results indicate that among boys there is continuity in problem behavior from childhood to adolescence and that such continuity is especially acute when early problem behavior takes the form of physical aggression Chronic physical aggression during the elementary school years specifically increases the risk for continued physical violence as well as other nonviolent forms of delinquency during adolescence However, this conclusion is reserved primarily for boys, because the results indicate no clear linkage between childhood physical aggression and adolescent offending among female samples despite notable similarities across male and female samples in the developmental course of physical aggression in childhood

Measuring the quality of relationships in consumer services: an empirical study

Abstract: Increasingly, firms are recognizing the value of establishing close relationships with their customers as a means of retaining existing customers. Also, firms are realizing that the intangible aspects of a relationship are not easily duplicated by competition, thus providing a sustainable competitive advantage to the firm. In this paper, we provide firms with a scale for measuring the quality of these intangible relationships between service firms and their customers. We then test this scale against the related, yet dissimilar scale for service quality to determine whether the relationship quality (RQ) scale adds any further explanation of behavioral intentions. Our results indicate that relationship quality is a distinct construct from service quality and that RQ is a better predictor of behavioral intentions than service quality.

Intentions to Use Self-Service Technologies: A Confluence of Multiple Attitudes

Abstract: The introduction of self-service technologies (SSTs) into the service encounter necessitates research to better understand customers’ attitudes toward service providers and technologies, and their intentions to use technology-based service delivery systems. In this research, the authors develop and empirically test three nested structural models that include a hierarchy of consumer attitudes toward both the interpersonal and the technological aspects of the encounter to better understand their intentions to use SSTs. The findings indicate that intentions to use SST options are driven by multiple, hierarchical attitudes. In addition to the direct effects of attitudes toward specific SSTs and individual employees, the findings confirm that higher order global attitudes toward service technologies influence intentions to use SSTs. Interestingly, the findings indicate that heavy SST users rely more on attitudes toward specific SSTs than do light SST users, who rely more heavily on global attitudes toward SSTs...

Cross-Border Listings and Price Discovery: Evidence from U.S.-Listed Canadian Stocks

Abstract: We examine the contribution of cross-listings to price discovery for a sample of Canadian stocks listed on both the Toronto Stock Exchange (TSE) and a U.S. exchange. We ¢nd that priceson the TSE and U.S. exchange are cointegrated and mutually adjusting. The U.S. share of price discovery ranges from 0.2 percent to 98.2 percent, with an average of 38.1 percent. The U.S. share is directly related to the U.S. share of trading and to the ratio of proportions of informative tradeson the U.S. exchange and the TSE, and inversely related to the ratio of bid-ask spreads. WITH THE ENHANCED GLOBALIZATION of ¢nancial markets, the number of non-U.S. ¢rms cross-listing shares on a U.S. exchange has substantially increased. Attracting non-U.S. listings is now a top priority of the U.S. stock exchanges. At the end of 2000, 420 non-U.S. ¢rmswere listed on the New York Stock Exchange (NYSE).The number of foreign ¢rmslisted on Nasdaq waseven higher.The popularity of international cross-listings has prompted many academic studies on the topic. 1 Most of these studies focus on the bene¢ts of international cross-listings, including the reduced cost of capital and the enhanced liquidity of a ¢rm’s stock. Studiessuch asAlexander, Eun, and Janakiramanan (1987, 1988) and Foerster and Karolyi (1993) suggest that the cost of capital declines because the portion of the risk premium that compensates for cross-border investment barriers dissipates. Miller (1999) and Foerster and Karolyi (1999) propose increased investor recognition as another possible explanation. Several studies examine changes in trading volume and costs due to international cross-listing. Foerster and Karolyi (1998) ¢nd that the bid-ask spreads in Canada decrease after the cross-listing of Canadian stocks in the United States. Domowitz, Glen, and Madhavan (1998) suggest that the impact of cross-listing is complex and depends on the degree of quote transparency, that is, the extent to which price information is observable in the two markets. Smith and So¢anos (1997) examine if cross-listing is a zerosum game, with increased trading in the United States being oiset by reduced

Triple Jeopardy and Beyond: Multiple Minority Stress and Resilience Among Black Lesbians

Abstract: SUMMARY This qualitative study explored the experiences of multiple minority stress and resilience among interviewees at a retreat for Black lesbians. Participants were a predominantly middle-class, highly educated sample of Black women (N= 19) between the ages of 26 and 68. The multicultural model of stress (Slavin, Rainer, McCreary, & Gowda, 1991) and the transactional model of resilience (Kumpfer, 1999) were theoretical frameworks for the study. Most of the participants discussed racism as a mundane and significant stressor, and contextualized their experiences of sexism and heterosexism through the prism of racism. Study findings provide empirical support for the "triple jeopardy" experience of Black lesbians (Greene, 1995), as well as the six predictors of resilience in Kumpfer's (1999) transactional model of resilience.

Linguistic and cultural barriers to care.

Abstract: CONTEXT: Primarily because of immigration, Asian Americans are one of the fastest growing and most ethnically diverse minority groups in the United States. However, little is known about their perspectives on health care quality.

Structure and Generation of Turbulence at Interfaces Strained by Internal Solitary Waves Propagating Shoreward over the Continental Shelf

Abstract: Detailed observations of the structure within internal solitary waves propagating shoreward over Oregon's continental shelf reveal the evolving nature of interfaces as they become unstable and break, creating turbulent flow. A persistent feature is high acoustic backscatter beginning in the vicinity of the wave trough and continuing through its trailing edge and wake. This is demonstrated to be due to enhanced density microstructure. Increased small-scale strain ahead of the wave trough compresses select density interfaces, thereby locally increasing stratification. This is followed by a sequence of overturning, high-density microstructure, and turbulence at the interface, which is coincident with the high acoustic backscatter. The Richardson number estimated from observations is larger than 1/4, indicating that the interface is stable. However, density profiles reveal these preturbulent interfaces to be O(10 cm) thick, much thinner than can be resolved with shipboard velocity measurements. By as...

Neighborhood Disadvantage, Individual Economic Distress and Violence Against Women in Intimate Relationships

Abstract: A continuing debate in sociological criminology involves the association of crime with economic disadvantage at both aggregate and individual levels of analysis. At the aggregate level, data from law enforcement sources suggest that rates of intimate violence are higher in disadvantaged neighborhoods. Disadvantaged neighborhoods may experience higher rates of intimate violence for compositional or contextual reasons, or rates may only appear to be higher because of differential reporting. Similarly, at the individual level, intimate violence appears more common among couples that are economically distressed, but whether economic distress triggers intimate violence is not certain. Using data from waves 1 and 2 of the National Survey of Families and Households and from the 1990 U.S. Census, we investigate the effects of neighborhood economic disadvantage and individual economic distress on intimate violence against women. Controlling for violence at time 1 and other individual level characteristics, we find that neighborhood economic disadvantage, neighborhood residential instability, male employment instability, and subjective financial strain influence the likelihood of violence at time 2. The relationship between neighborhood disadvantage and intimate violence appears to reflect both compositional and contextual effects.

Exercise self-efficacy in older adults: social, affective, and behavioral influences.

Abstract: A 6-month randomized controlled trial examined the effect of walking and stretching/toning activity on changes in self-efficacy to overcome barriers and engage in incremental periods of activity in older, formerly sedentary adults (N = 174, Mage = 65.5 years). Additionally, we were interested in the extent to which social, affective, and behavioral influences contributed to self-efficacy at the end of the 6-month program. Multiple sample latent growth curve analyses revealed a nonsignificant curvilinear growth pattern for barriers efficacy with increases in efficacy occurring from base-line to 2 months and then declining at 4 and 6 months. In the case of efficacy related to continued activity participation, there was a significant growth pattern demonstrating declines in efficacy over the 4 time points. Structural modeling analyses revealed significant direct effects of physical activity, affect experienced during activity, and exercise social support on both types of self-efficacy. These relationships were not significantly different between modes of activity. The findings are discussed in terms of the need to target sources of efficacy information prior to program end and the implications that such an approach might have for long-term maintenance of physical activity in older adults.

Changes in diabetes self-care behaviors make a difference in glycemic control: the Diabetes Stages of Change (DiSC) study.

Abstract: OBJECTIVE — This study compared diabetes Treatment As Usual (TAU) with Pathways To Change (PTC), an intervention developed from the Transtheoretical Model of Change (TTM), to determine whether the PTC intervention would result in greater readiness to change, greater increases in self-care, and improved diabetes control. RESEARCH DESIGN AND METHODS — Participants were stratified by diabetes treatment and randomized to treatment with PTC or TAU as well as being randomized regarding receipt of free blood testing strips. The PTC consisted of stage-matched personalized assessment reports, self-help manuals, newsletters, and individual phone counseling designed to improve readiness for self-monitoring of blood glucose (SMBG), healthy eating, and/or smoking cessation. A total of 1,029 individuals with type 1 and type 2 diabetes who were in one of three pre-action stages for either SMBG, healthy eating, or smoking were recruited. RESULTS — For the SMBG intervention, 43.4% of those receiving PTC plus strips moved to an action stage, as well as 30.5% of those receiving PTC alone, 27.0% of those receiving TAU plus strips, and 18.4% of those receiving TAU alone (P 0.001). For the healthy eating intervention, more participants who received PTC than TAU (32.5 vs. 25.8%) moved to action or maintenance (P 0.001). For the smoking intervention, more participants receiving PTC (24.3%) than TAU (13.4%) moved to an action stage (P 0.03). In intention-to-treat (ITT) analysis of those receiving the SMBG intervention, PTC resulted in a greater reduction of HbA1c than TAU, but this did not reach statistical significance. However, in those who moved to an action stage for the SMBG and healthy eating interventions, HbA1c was significantly reduced (P 0 0.001). Individuals who received the healthy eating intervention decreased their percentage of calories from fat to a greater extent (35.2 vs. 36.1%, P 0.004), increased servings of fruit per day (1.89 vs. 1.68, P 0.016), and increased vegetable servings (2.24 vs. 2.06, P 0.011) but did not decrease weight. However, weight loss for individuals who received the healthy eating intervention and who increased SMBG frequency as recommended was significantly greater, with a 0.26-kg loss in those who remained in a pre-action SMBG stage but a 1.78-kg loss in those performed SMBG as recommended (P 0. 01). CONCLUSIONS — This study demonstrates that this intervention has the potential of positively impacting the health of broad populations of individuals with diabetes, not just the minority who are ready for change. Diabetes Care 26:732–737, 2003

Forest ecosystem carbon and nitrogen accumulation during the first century after agricultural abandonment

Abstract: Forests of the northeastern United States are expected to serve as a substantial sink for carbon (C) and nitrogen (N) as they recover from extensive clearing and agriculture. However, questions remain concerning the rate, distribution, and duration of this potential sink. We used a chronosequence approach to determine changes in ecosystem C and N during the first 115 years of forest development after agricultural abandonment in Rhode Island, USA. All sites had similar soils, climate, land-use history, and dominant overstory vegetation (Pinus strobus), but differed in time since agricultural abandonment. Total ecosystem C increased linearly across the chronosequence at a mean rate of 2.10 Mg C·ha–1·yr–1. Most of the C was sequestered into plant biomass (73%) with less stored in the forest floor (17%) and deep mineral soil (6%; 20–70 cm depth). Total ecosystem N did not change over time; instead N accumulated in the forest floor (11.6 kg N·ha–1·yr–1) and plant biomass (4.1 kg N·ha–1·yr–1), and these increas...

Determination of the crystalline phases of poly(vinylidene fluoride) under different preparation conditions using differential scanning calorimetry and infrared spectroscopy

Abstract: A method with good precision has been developed to quantitatively measure the degree of α-, β-, and γ crystallinity in poly(vinylidene fluoride) (PVDF) by means of infrared spectroscopy. The phase composition of solution-deposited PVDF films was found to be strongly influenced by the presence of hydrophilic residues on the silicon substrate, the relative humidity present at film deposition, the spatial position on the substrate, and the thermal treatment of the deposited film. Films produced on pristine surfaces gave predominantly α-phase PVDF, but when a layer of polar solvent (acetone or methanol) remained on the surface, the films produced were predominantly γ phase. Higher humidity promoted a higher fraction of γ crystallinity in the solution-deposited PVDF films. Solution-cast films had highly variable composition across the substrate, whereas spin-cast films were uniform. High-temperature annealing of PVDF films normally converts the polymer to the γ phase, but annealing the film while still attached to the silicon substrate inhibited this phase transformation. Low-temperature annealing of freestanding films led to a previously unreported thermal event in the DSC, a premelting process that is a kinetic event, assigned to a crystalline relaxation. Higher-temperature annealing gave a double endotherm, assigned to melting of different-sized crystalline domains. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1093–1100, 2003

Landslide tsunami case studies using a Boussinesq model and a fully nonlinear tsunami generation model

Abstract: . Case studies of landslide tsunamis require integration of marine geology data and interpretations into numerical simulations of tsunami attack. Many landslide tsunami generation and propagation models have been proposed in recent time, further motivated by the 1998 Papua New Guinea event. However, few of these models have proven capable of integrating the best available marine geology data and interpretations into successful case studies that reproduce all available tsunami observations and records. We show that nonlinear and dispersive tsunami propagation models may be necessary for many landslide tsunami case studies. GEOWAVE is a comprehensive tsunami simulation model formed in part by combining the Tsunami Open and Progressive Initial Conditions System (TOPICS) with the fully non-linear Boussinesq water wave model FUNWAVE. TOPICS uses curve fits of numerical results from a fully nonlinear potential flow model to provide approximate landslide tsunami sources for tsunami propagation models, based on marine geology data and interpretations. In this work, we validate GEOWAVE with successful case studies of the 1946 Unimak, Alaska, the 1994 Skagway, Alaska, and the 1998 Papua New Guinea events. GEOWAVE simulates accurate runup and inundation at the same time, with no additional user interference or effort, using a slot technique. Wave breaking, if it occurs during shoaling or runup, is also accounted for with a dissipative breaking model acting on the wave front. The success of our case studies depends on the combination of accurate tsunami sources and an advanced tsunami propagation and inundation model.

Combretastatin A-4 analogues as antimitotic antitumor agents.

Abstract: Tubulin protein is a major target for anticancer drug discovery. As a result, antimitotic agents constitute an important class of the current anticancer drugs. Hundreds of tubulin inhibitors, naturally occurring, semisynthetic or synthetic, have been reported. Among these, combretastatin A-4 (CA-4), isolated from a South African tree Combretum caffrum, is one of the most potent antimitotic agents. CA-4 shows strong cytotoxicity against a variety of cancer cells, including multi-drug resistant cancer cell lines. It has also been demonstrated to exert highly selective effects in proliferating endothelial cells. CA-4 disodium phosphate (CA4DP), a water-soluble prodrug of CA-4, shows potent antivascular and antitumor effects in a wide variety of preclinical tumor models. Consequently, a number of CA-4 analogues has been synthesized and evaluated. In this paper, the structure-activity relationships and pharmacological properties of the CA-4 derivatives as a class of potent antimitotic anticancer agents are reviewed and discussed.

Effects of Forest Roads on Understory Plants in a Managed Hardwood Landscape

Abstract: The effect of forest roads on species distribution and dispersal is an important conservation and management issue. We examined distributions of understory plants and their relationships to unpaved forest roads in a northern hardwood landscape in the Chequamegon National Forest, Wisconsin (U.S.A.). At six dif- ferent sites, we recorded species cover, canopy cover, litter depth and cover, and bare ground at 11 distances (0, 5, 10, 15, 20, 30, 45, 60, 90, 120, and 150 m) from the road edge. At each of the 11 distances, we estab- lished a 60-m transect parallel to the road edge, within which we sampled 10 randomly placed 1 � 1 m plots (660 plots). We examined changes in species abundance (percent species cover per plot), richness, and Shan- non-Wiener diversity ( H � ) with distance from the roads in an effort to determine the degree and magnitude of road effects on plant distribution. The species richness and Hof native plants and the abundance of exotic species were clearly related to distance from the roads. Exotic species were most prevalent within 15 m of roads, occurring infrequently in the interior forest. The richness and Hof native species were lower on the roadsides but reached interior-forest levels within a short distance (5 m) from the roads. The roads appeared to be associated with a disturbance corridor that affected site variables up to 15 m into the hardwood stands. At our six sites we detected 117 species, 25% of which occurred more frequently near the road, with only 12% having a 90% or greater preference for the forest interior. Our results suggest that roads have associated ef- fects that alter interior-forest conditions and thus plant species composition and abundance; however, these effects are limited in depth of penetration into managed forests.

Laboratory models of the thermal evolution of the mantle during rollback subduction

Abstract: The subduction of oceanic lithosphere plays a key role in plate tectonics, the thermal evolution of the mantle and recycling processes between Earth's interior and surface. Information on mantle flow, thermal conditions and chemical transport in subduction zones come from the geochemistry of arc volcanoes1,2,3, seismic images4,5 and geodynamic models6,7,8,9,10. The majority of this work considers subduction as a two-dimensional process, assuming limited variability in the direction parallel to the trench. In contrast, observationally based models increasingly appeal to three-dimensional flow associated with trench migration and the sinking of oceanic plates with a translational component of motion11 (rollback). Here we report results from laboratory experiments that reveal fundamental differences in three-dimensional mantle circulation and temperature structure in response to subduction with and without a rollback component. Without rollback motion, flow in the mantle wedge is sluggish, there is no mass flux around the plate and plate edges heat up faster than plate centres. In contrast, during rollback subduction flow is driven around and beneath the sinking plate, velocities increase within the mantle wedge and are focused towards the centre of the plate, and the surface of the plate heats more along the centreline.

Delta response to decline in sediment supply from the Yangtze River: evidence of the recent four decades and expectations for the next half-century

Abstract: In order to examine the delta response to decline in sediment supply from the Yangtze River during the recent decades, bathymetric maps of the Yangtze subaqueous delta surveyed from 1958 to 1997 were analyzed together with the river sediment dataset of the same period. The net accretion rate over the study area decreased from 38 mm/yr in 1958–1978 to 8 mm/yr in 1978–1997, while the river sediment discharge decreased from 466×106 to 394×10 6 t/yr and the suspended sediment concentration decreased from 0.543 to 0.448 kg/m3 during the same periods, respectively. The outer subaqueous delta is more sensitive to decline in river sediment load in contrast with the inner subaqueous delta. From 1958–1978 to 1978–1997, the net accretion rate decreased from 51 to 2 mm/yr in the outer subaqueous delta and from 25 to 14 mm/yr in the inner subaqueous delta. The accretion rate decreased more rapidly than the river sediment discharge because the amount of sediment transported out of the delta has not decreased. A concept of the critical threshold of river sediment discharge that separates delta progradation from recession is proposed. Although this critical value was found to change temporally and spatially, it was instrumental in predicting the future delta response. Under the impacts of human activities, particularly, the Three Gorges Dam Project, the river sediment load would be reduced below the critical value during the next five decades. This would result in a general delta recession replacing delta progradation; the recession would occur first in the outer subaqueous delta.

The Cape Cauldron: A regime of turbulent inter-ocean exchange

Abstract: Combining in-situ Lagrangian intermediate depth velocity measurements from the KAPEX (Cape of Good Hope Experiments) float program with sea-surface height data, this study reviews the inter-ocean exchange mechanisms around southern Africa. In the southeastern Cape Basin, a highly energetic field of coexisting anticyclonic and cyclonic eddies is documented. Agulhas Rings of typically 200 km diameter are observed to merge, split, deform, and to reconnect to the Agulhas Retroflection. Concomitant, slightly smaller cyclones are observed to drift across the northwestward migration path of the Agulhas Rings. These cyclones, with typical diameters of 120 km, are formed within the Cape Basin along the African shelf, inshore of the Agulhas Current, and in the subantarctic region south of Africa. The data suggest the annual formation of 3–6 long-lived Agulhas Rings that eventually cross 5°E longitude, while approximately twice the number of rings occur in the southeastern Cape Basin. Within this region, cyclones outnumber anticyclones by a factor of 3:2. Both cyclones and anticyclones extend through the upper thermocline into the intermediate depth layer. Mean drifts of anticyclones are 3.8±1.2 cm s−1 to the northwest, while cyclones follow a west–southwestward route at 3.6±0.8 cm s−1. Transport estimates suggest that the intermediate depth layer in the southeastern Cape Basin is primarily supplied from the east (approximately 9 Sv), with minor direct inflow from the Atlantic to the west and south. Cyclone/anticyclone interaction is surmised to result in vigorous stirring and mixing processes in the southeastern Cape Basin, which necessitates a review of the traditional concept of Indo-Atlantic inter-ocean exchange. We propose to limit the concept of “isolated Agulhas Rings embedded in a sluggish Benguela Drift” to the northwestern Cape Basin and beyond, while linking this regime to the Agulhas Retroflection proper through a zone of turbulent stirring and mixing in the southeastern Cape Basin, named for the first time the “Cape Cauldron” hereinafter.

Toward developing a complete understanding: A social science research agenda for marine protected areas

Abstract: Although many types of MPAs exist—including reserves, sanctuaries, and parks—each involves a group of people collectively engaged in decision-making and most MPAs have both biological and social goals. Biological goals include rehabilitating damaged habitats, sustaining biodiversity, protecting marine life, and providing a laboratory for basic natural science inquiry. Examples of social goals include restoring commercial, recreational, or subsistence fisheries, creating ecotourism experiences, generating economic opportunities, and empowering coastal communities. Biological and social goals may be contradictory or unequally appealing to different constituency groups, resulting in controversy and conflict. These dynamics contribute to the high rate of MPA failure—approaching 90% in some countries (White et al. 2002). In most cases, MPA design and impacts are examined principally from a biological perspective. Use of mainly biological evaluation criteria may contribute to MPAs being categorically defined as a successful, when, in fact, the story is more complex (Christie in press). A particular MPA may be both a biological “success”—resulting in increased fish abundance and diversity and improved habitat—and a social “failure”—lacking broad participation in management, sharing of economic benefits, and conflict resolution mechanisms. Short-term biological gains will likely disappear unless these social issues are addressed (Pollnac et al. 2001; Christie et al. 2002) Social science research is conducted too late in the design process to influence policies despite the understanding that such research is fundamentally important (Salm et al. 2000; NRC 2001; Mascia et al. 2003; Pomeroy and Hunter in press). In general, social science research that is “too little, too late” in the MPA design and implementation processes results in a poor understanding of frequently contentious social interactions operating on multiple levels (local, national, international, gender, class, ethnicity), unintended negative consequences, missed opportunities for positive change and reallocation of resources, and an incomplete scientific record. For example, managers involved in the Florida Keys National Marine Sanctuary acknowledge that they initially underestimated the importance of a broadly participative process grounded in a sound understanding of constituents’ interests and activities—a costly oversight that set back the management process considerably (Suman et al. 1999; Causey 2000). Toward developing a complete understanding: A social science research agenda for marine protected areas

An Illustration of a Longitudinal Cross-Lagged Design for Larger Structural Equation Models

Abstract: A model of HIV behavior risk is tested, using a fully cross-lagged, longitudinal design, to illustrate the analysis of larger (i.e., 3 or more variables across 3 or more time points) structural equation models. The constructs in this integrated model were (a) Perceived Risk for AIDS, (b) Decisional Balance (relative weighing of benefits and barriers of condom use), (c) Self-Efficacy for Condom Use, (d) Lifetime Number of Sex Partners, and (d) Behavior Risk. Data were analyzed from 527 women living in a New England community who completed lifestyle surveys at 3 time points. Results of the cross-lagged analysis indicated a reciprocal, positive relation between Self-Efficacy for Condom Use and Decisional Balance. Behavior Risk for HIV was associated with higher Perceived Risk, lower Self-Efficacy for Condom Use, and lower Decisional Balance. The model showed excellent fit to the data and explained substantial variance in Time 3 measures of model constructs. Interpretations, as well as strengths and limitatio...

Annual cycle in abundance, distribution, and size in relation to hydrography of important copepod species in the western Arctic Ocean

Abstract: A yearlong study of the zooplankton biomass and the abundance, vertical distribution, life stage proportions, and body size and condition for five target copepod species ( Calanus glacialis , C. hyperboreus , Metridia longa , Microcalanus pygmaeus , Oithona similis ) was conducted from October 1997 to October 1998 in the Western Arctic Ocean. The research was staged from Ice Station SHEBA that drifted from Canadian Basin over the Northwind Ridge and Chukchi Plateau and back over the Basin during this period. Four hydrographic regimes were surveyed during the period of the study. Zooplankton biomass was least over the basin during the fall and winter and greatest over the Chukchi Plateau during summer, with most biomass in the 200–1500 m depth interval except during summer when greatest biomass was present in the upper 200 m. The five copepod species followed two general life history strategies: (1) sustained reproduction with all life stages present throughout the year and constant depth distribution ( M. longa , M. pygmaeus , O. similis ) and (2) pulsed reproduction with overlapping cohorts present and ontogenetic redistribution of preferred depths through the year ( C. glacialis , C. hyperboreus ). Body size and condition did not demonstrate consistent temporal or regional patterns. Based on population age structure, both C. hyperboreus and C. glacialis were reproducing in the Arctic Ocean. However, extremely low abundances of C. glacialis suggested that this species may not be self-sustaining in the Arctic Ocean. Plankton biomass was consistent with that observed in recent studies and supported an emerging paradigm of a more productive Arctic Ocean than traditionally believed.

Regional-scale chemical transport modeling in support of the analysis of observations obtained during the TRACE-P experiment

Abstract: [1] Data obtained during the TRACE-P experiment is used to evaluate how well the CFORS/STEM-2K1 regional-scale chemical transport model is able to represent the aircraft observations. Thirty-one calculated trace gas and aerosol parameters are presented and compared to the in situ data. The regional model is shown to accurately predict many of the important features observed. The mean values of all the model parameters in the lowest 1 km are predicted within ±30% of the observed values. The correlation coefficients (R) for the meteorological parameters are found to be higher than those for the trace species. For example, for temperature, R > 0.98. Among the trace species, ethane, propane, and ozone show the highest values (0.8 < R < 0.9), followed by CO, SO2, and NOy. NO and NO2 had the lowest values (R < 0.4). Analyses of pollutant transport into the Yellow Sea by frontal events are presented and illustrate the complex nature of outflow. Biomass burning from SE Asia is transported in the warm conveyor belt at altitudes above ∼2 km and at latitudes below 30N. Outflow of pollution emitted along the east coast of China in the postfrontal regions is typically confined to the lower ∼2 km and results in high concentrations with plume-like features in the Yellow Sea. During these situations the model underpredicts CO and black carbon (among other species). An analysis of ozone production in this region is also presented. In and around the highly industrialized regions of East Asia, where fossil fuel usage dominates, ozone is NMHC-limited. South of ∼30–35N, ozone production is NOx-limited, reflecting the high NMHC/NOx ratios due to the large contributions to the emissions from biomass burning, biogenics sources, and biofuel usage in central China and SE Asia.

Numerical Simulation of Sea Surface Directional Wave Spectra under Hurricane Wind Forcing

Abstract: Numerical simulation of sea surface directional wave spectra under hurricane wind forcing was carried out using a high-resolution wave model. The simulation was run for four days as Hurricane Bonnie (1998) approached the U.S. East Coast. The results are compared with buoy observations and NASA Scanning Radar Altimeter (SRA) data, which were obtained on 24 August 1998 in the open ocean and on 26 August when the storm was approaching the shore. The simulated significant wave height in the open ocean reached 14 m, agreeing well with the SRA and buoy observations. It gradually decreased as the hurricane approached the shore. In the open ocean, the dominant wavelength and wave direction in all four quadrants relative to the storm center were simulated very accurately. For the landfall case, however, the simulated dominant wavelength displays noticeable overestimation because the wave model cannot properly simulate shoaling processes. Direct comparison of the model and SRA directional spectra in all four quadrants of the hurricane shows excellent agreement in general. In some cases, the model produces smoother spectra with narrower directional spreading than do the observations. The spatial characteristics of the spectra depend on the relative position from the hurricane center, the hurricane translation speed, and bathymetry. Attempts are made to provide simple explanations for the misalignment between local wind and wave directions and for the effect of hurricane translation speed on wave spectra.

Replacing the Nile: Are Anthropogenic Nutrients Providing the Fertility Once Brought to the Mediterranean by a Great River?

Abstract: Prior to construction of the Aswan High Dam, the annual Nile flood delivered about 7–11 × 103 t of biologically available phosphorus (P), at least 7 × 103 t of inorganic nitrogen (N), and 110 × 103 t of silica (Si) to the Mediterranean coastal waters off Egypt. These nutrients stimu-lated a dramatic “Nile bloom” of diatoms which supported a productive fishery. After closure of the dam in 1965, flow from the Nile was reduced by over 90%, and the fishery collapsed. It remained unproductive for about 15 years. The fishery began a dramatic recovery during the 1980s, coincident with increasing fertilizer use, expanded agri-cultural drainage, increasing human population, and dra-matic extensions of urban water supplies and sewage collection systems. Calculations of the potential anthro-pogenic contribution of nutrients (P and N, but not Si) are consistent with the hypothesis that human sewage and agricultural drainage now support the fertility once provided by the Nile, though the nature of the product...

Fabrication, characterization, and dynamic behavior of polyester/TiO2 nanocomposites

Abstract: Unsaturated polyester resin specimens embedded with small loadings of 36 nm average diameter TiO 2 particles were fabricated using a direct ultrasonification method to study the effects of nanosized particles on nanocomposite bulk mechanical properties. The ultrasonification method employed produced nanocomposites with excellent particle dispersion as verified by transmission electron microscopy (TEM). Quasi-static fracture toughness, tension, and compression testing was carried out. The presence of the particles had the greatest effect on fracture toughness; negligible influence was observed in the remaining quasi-static properties. Scanning electron microscopy (SEM) of fracture surfaces was carried out to identify toughening mechanisms. The inadequacy of the bond between the filler and the matrix and the presence of minor particle agglomerations in specimens containing higher volume fractions of particles were believed to be responsible for a consistent decrease in property values beyond a volume fraction of 1 vol.%. Dynamic fracture toughness testing was carried out, and an increase in dynamic fracture toughness relative to quasi-static fracture toughness was observed. High strain rate testing conducted using a split Hopkinson pressure bar (SHPB) apparatus revealed a moderate stiffening effect with increasing particle volume fraction, although no marked effect was observed on the ultimate strength.

Seasonal and ENSO variability in global ocean phytoplankton chlorophyll derived from 4 years of SeaWiFS measurements

Abstract: [1] The 4-year, calibrated SeaWiFS data set provides a means to determine seasonal and other sources of phytoplankton variability on global scales, which is an important component of the total variability associated with ocean biological and biogeochemical processes. We used empirical orthogonal function (EOF) analysis on a 4-year time series of global SeaWiFS chlorophyll a measurements to quantify the major seasonal (as well as the late El Nino and La Nina phase of the 1997–1998 ENSO) signals in phytoplankton biomass between 50°S and 50°N, and then a second analysis to quantify summer patterns at higher latitudes. Our results help place regional satellite chlorophyll variability within a global perspective. Among the effects we resolved are a 6-month phase shift in maximum chlorophyll a concentrations between subtropical (winter peaks) and subpolar (spring-summer peaks) waters, greater seasonal range at high latitudes in the Atlantic compared to the Pacific, an interesting phasing between spring and fall biomass peaks at high latitudes in both hemispheres, and the effects of the 1998 portion of the 1997–1998 ENSO cycle in the tropics. Our EOF results show that dominant seasonal and ENSO effects are captured in the first six of a possible 184 modes, which explain 67% of the total temporal variability associated with the global mean phytoplankton chlorophyll pattern in our smoothed data set. The results also show that the time (seasonal)/space (zonal) patterns between the ocean basins and between the hemispheres are similar, albeit with some key differences. Finally, the dominant global patterns are consistent with the results of ocean models of seasonal dynamics based on seasonal changes to the heating and cooling (stratification/destratification) cycles of the upper ocean.