Showing papers by "University of North Carolina at Wilmington published in 1996"

The impacts of mobile fishing gear on seafloor habitats in the gulf of Maine (Northwest Atlantic): Implications for conservation of fish populations

Abstract: Fishing gear alters seafloor habitats, but the extent of these alterations, and their effects, have not been quantified extensively in the northwest Atlantic. Understanding the extent of these impacts, and their effects on populations of living marine resources, is needed to properly manage current and future levels of fishing effort and fishing power. For example, the entire U.S. side of the Gulf of Maine was impacted annually by mobile fishing gear between 1984 and 1990, based on calculations of area swept by trawl and dredge gear. Georges Bank was imparted three to nearly four times annually during the same period. Studies at three sites in the Gulf of Maine (off Swans Island, Jeffreys Bank, and Stellwagen Bank) showed that mobile fishing gear altered the physical structure (=complexity) of benthic habitats. Complexity was reduced by direct removal of biogenic (e.g., sponges, hydrozoans, bryozoans, amphipod tubes, holothurians, shell aggregates) and‐ sedimentary (e.g., sand waves, depressions)...

Pulsed delivery of subthermocline water to Conch Reef (Florida Keys) by internal tidal bores

Abstract: Internal tidal bores generated by breaking internal waves cause dramatic, high-frequency variation in temperature, salinity, water velocities, and concentration of chlorophyll a on Conch Reef, Florida Keys. The arrival of bores on the reef slope is linked to a semidiurnal internal tide and is marked by temperature drops of up to 5.4?C and salinity increases of up to 0.60oo in 1-20 min. These changes are accompanied by the sudden onset of upslope flow 1-15 m above the bottom with speeds of 10-30 cm s-'. Cool, high-salinity water is transported from below the thermocline seaward of the reef and is resident on the reef slope for up to 4 h before it mixes with surface waters and recedes downslope. Compared with ambient surface water, this deep water can contain significantly elevated concentrations of dissolved nitrate. Physical variability produced by this mechanism increases significantly with depth on the reef slope. Analysis of 3-yr temperature records indicates the arrival of internal bores is a consistent feature at this site from May through November, with peak activity in July-September. Pulsed delivery of subthermocline water appears to significantly affect the temperature, nutrient, and particle flux regimes on this coral reef.

Ontogeny of place learning in children as measured in the Radial Arm Maze, Morris Search Task, and Open Field Task.

Abstract: Children and adults were tested on 3 place learning tasks. Children under the age of 7 were inferior to older subjects in solving the tasks by using spatial relational solutions, but subjects of all ages were equally proficient in solving the task by using simple stimulus-reward associations (cued solutions). Accurate performance on the cued versions suggests that neither the general response demands nor the large size of testing environments rendered the tasks differentially inappropriate for young children. Instead, the nature of the cognitive demands were responsible for different levels of performance across the age groups. Because, in animal studies, spatial relational solutions but not cued solutions of these tests require mature and undamaged medial temporal lobe structures, the results suggest that these systems are not fully developed in humans before approximately 7 years of age.

Video-monitored predation by Caribbean reef fishes on an array of mangrove and reef sponges

Abstract: Although predation by fishes is thought to structure benthic invertebrate communities on coral reefs, evidence to support this claim has been difficult to obtain. We deployed an array of eight sponge species on Conch Reef (16 m depth) off Key Largo, Florida, USA, and used a remote video-camera to record fish activity near the array continuously during five daylight periods (6 h for 1 d, at least 11.5 h for 4 d) and one night period (11 h). Of the eight sponge species, four were from adjacent reefs (Agelas wiedenmayeri, Geodia neptuni, Aplysina fistularis, and Pseudaxinella lunaecharta), and four were from a nearby mangrove habitat (Chondrosia collectrix, Geodia gibberosa, Halichondria sp., andTedania ignis). Each species of reef sponge was chosen to match the corresponding mangrove species in form and color (black, brown, yellow, and red, respectively). Predation events only occurred during daylight hours. Tallies of the number of times fishes bit sponges revealed intense feeding by the expected species of sponge-eating fishes, such as the angelfishHolacanthus bermudensis, H. tricolor, andPomacanthus arcuatus, the cowfishLactophrys quadricornis, and the filefishCantherhines pullus, but surprisingly also by the parrotfishSparisoma aurofrenatum andS. chrysopterum. Of 35 301 bites recorded, 50.8% were taken by angelfish, 34.8% by parrotfish, and 13.7% by trunkfish and filefish. Mangrove sponges were preferred by all reef fishes; 96% of bites were taken from mangrove species, with angelfish preferringChondrosia collectrix and parrotfish preferringGeodia gibberosa. Fishes often bit the same sponge repetitively, and frequently consumed entire samples within 30 min of their deployment. Sponge color did not influence fish feeding. Two of the four mangrove sponge-species deployed on the array were also found living in cryptic habitats on adjacent reefs and were rapidly consumed by fishes when exposed. Our results demonstrate the importance of fish predation in controlling the distribution of sponges on Caribbean reefs.

A new test of classic strain theory

Abstract: The central variable in classic strain theory is the individual's level of dissatisfaction or frustration with his or her monetary status. This variable, however, has been ignored in virtually all tests of the theory. Most often, strain is measured indirectly in terms of the disjunction between aspirations and expectations. This paper directly measures dissatisfaction with monetary status, and draws on classic strain theory to explore the determinants and effects of such dissatisfaction. Data from a sample of adults in Cincinnati indicate that dissatisfaction is highest among objectively deprived individuals and those who desire a lot of money, have low expectations for making a lot of money, and feel relatively deprived. Further, dissatisfaction has a positive effect on both income-generating crime and drug use. This effect is strongest among those who have criminal friends and beliefs conductive to crime. Unlike the findings in much previous research, these data provide qualified support for classic str...

A Critical Incident Approach to Examining the Effects of Service Failures on Customer Relationships The Case of Swedish and U.S. Airlines

Abstract: This article presents the results of empirical studies of critical incidents in airline services in Sweden and the United States. The main aim is to describe and analyze service break downs from the customer's point of view and thus create a basis for crisis management. The aim is also to compare Sweden, a monopoly market, with the United States, a market with keen competition in airline services. The discussion is based on personal interviews with 320 customers and 80 airline employees in Sweden and 241 customers and 100 employees in the United States. The study focuses on negative critical incidents in the relations between the service provider and business passengers

Cognitive gender differences in very young children parallel biologically based cognitive gender differences in monkeys.

Abstract: Infant humans were trained on 2 cognitive tests that have previously revealed, in infant monkeys, a double dissociation that was reversible by perinatal manipulations of androgens and ablations of specific brain sites. Children showed the same sex-linked behavior found with infant monkeys: young boys were superior on the object reversal task and young girls were superior on the concurrent discrimination task. As happened previously with infant monkeys, the gender difference was not apparent in older human subjects. Thus, early in ontogeny, cognitive gender differences have now been discovered in both humans and monkeys, probably a result of gender differences in androgens that influence the maturation rate of specific brain systems.

Religion, social bonds, and delinquency

Abstract: Although criminologists have generally been indifferent or even hostile to the idea that religion inhibits criminal deviance, evidence of a consistent inverse relationship between religion and deviance—including crime and delinquency—has steadily accumulated over the last three decades. Yet controversy abounds concerning the extent to which this relationship is shaped by offense type, group affiliation, and other religious and social contexts. Some researchers have also claimed that, in fully specified models with controls for secular bonds, religion has no direct impact on delinquency. Using comprehensive measures of religion, secular social bonds, and delinquency, the present study seeks to resolve questions concerning the relative efficacy of religion as an inhibitor of delinquency. Unlike prior research, our models also include measures of three separate dimensions of religiosity (religious activities, salience, and “hellfire") and peer religiosity. In our most fully specified models, we find that gen...

A mixed‐integer programming approach for the international facilities location problem

Abstract: For many years, facilities location problems have attracted a great deal of attention in the literature. As a result, there is now a variety of methods for solving these problems. However, due to the recent interest, little research is found relating to the issues concerning international facilities location problems. Furthermore, in spite of the extensive modelling work done on facilities location, little modelling research exists on location problems. Provides a capacitated multi‐period, 0‐1 mixed integer programming formulation for the international facilities location problem and discusses its applications to an actual company case. This application is carried out to demonstrate not only how the model can be applied in practice but also to show its potential benefits when compared to other methods.

Settlement of the tube worm Hydroides dianthus (Polychaeta: Serpulidae): cues for gregarious settlement

Abstract: The larvae of many benthic marine invertebrates settle to form conspecific aggregations and are thought to rely on chemical cues associated with adults as indicators of habitat suitability, although the identification of inductive compounds has proven difficult. Still-water laboratory assays carried out during the summers of 1992 and 1993 with larvae of the serpulid polychaete, Hydroides dianthus (Verrill, 1873), demonstrate that unidentified water-borne compound(s) were responsible for gregarious settlement of competent larvae. Unlike inductive compounds associated with other tube-dwelling polychaetes, the settlement cue was soluble in water and was not associated with the tube, but rather with the body of live adults. In assay chambers divided by a 52-μm mesh barrier, a greater percentage of larvae settled on biofilmed substrata when adult worms were present on the other side of the barrier than when adults were absent. Settlement in response to conspecific adults, live worms removed from their tubes, and amputated tentacular crowns of live worms was significantly greater than settlement in response to dead worms, empty tubes, or biofilmed slides. The settlement inducer appears to emanate from the openings of occupied tubes; settlement was greatest along the anterior two-fifths of the tube of living conspecific adults. A single adult was equally capable of eliciting a gregarious response as were five or 25 conspecifics, and newly settled juveniles began to elicit gregarious settlement after approximately 96 h. Extraction of aggregations of adult worms with organic solvents removed the inductive capacity of the tissue, and activity was found in both nonpolar and polar fractions of an extraction series.

Does the skeleton of a sponge provide a defense against predatory reef fish

Abstract: Sponge tissue often contains two structural components in high concentrations: spicules of silica, and refractory fibers of protein (spongin). Some terrestrial plants contain analogous structures, siliceous inclusions and refractory lignins, that have been demonstrated to deter herbivory. We performed feeding experiments with predatory reef fish to assess the deterrent properties of the structural components of three common Caribbean demosponges, Agelas clathrodes, Ectyoplasia ferox, and Xestospongia muta. The concentrations of spicules and spongin in the tissues varied widely between the three species, but when assayed at their natural volumetric concentrations, neither spicules (all three species assayed) nor the intact spiculated spongin skeleton (A. clathrodes and X. muta assayed) deterred feeding by reef fish in aquarium or field assays using prepared foods of a nutritional quality similar to, or higher than, that of sponge tissue. Spicules deterred feeding in aquarium assays when incorporated into prepared foods of a nutritional quality lower than that of sponge tissue (15-19 times less protein), but spiculated spongin skeleton was still palatable, even in prepared foods devoid of measurable protein, and even though spicules embedded in spongin were oriented in their natural conformation. Based on comparisons of the nutritional qualities of the tissues of the three sponge species and of the prepared foods, sponge tissue would have to be much lower in food value (5 times less protein or lower) for spicules to provide an effective defense, and spicules in combination with the spongin skeleton would be unlikely to provide an effective defense regardless of the nutritional quality of the tissue. Unlike terrestrial plants, marine sponges may use silica and refractory fibers solely for structural purposes.

10 Stimulus equivalence: A class of correlations, or a correlation of classes?

Abstract: Publisher Summary The chapter discusses stimulus equivalence and describes experiments in which the reversals of baseline conditional discriminations appear to have different effects across probe trial types (i.e., reflexivity, symmetry, and transitivity/equivalence). It examines other empirical evidence performance on the various probe trial types that may differ in potentially important ways and reviews studies that use measures other than probe trials to assess equivalence-like phenomena. The theme considered throughout is a fundamental one for even the simplest of analytic units. The mathematical definition of equivalence specifies only required test outcomes, not the make-up of the behavioral unit(s) that includes these outcomes. The predictive value of the set theory framework is undeniable, and the structured approach that this framework has provided for the study and training of complex behavioral repertoires, often termed “cognitive,” has yielded impressive results. A definition of equivalence that allowed for correspondence among three independent stimulus control relations provides even greater generality while maintaining the precision and rigor of the set theory framework.

Coastal rainwater hydrogen peroxide: Concentration and deposition

Abstract: Correlation analysis between rainwater component concentrations (hydrogen peroxide, hydrogen ion, nitrate, nonseasalt sulfate and chloride ion) was used to investigate patterns of variation in hydrogen peroxide concentrations in rain collected in Wilmington, North Carolina, a coastal southeastern United States location, between October 1992, and October 1994. Rainwater hydrogen peroxide concentrations in general correlated positively with the pollutant components (hydrogen ion, nitrate and non-seasalt sulfate). This pattern suggests that destruction of hydrogen peroxide by sulfur dioxide is not the dominant factor controlling the concentration of hydrogen peroxide in this rainwater, with the possible exception of winter rain from coastal storms where an inverse correlation between hydrogen peroxide and nonseasalt sulfate was observed. Sequential sampling indicates rapid production of hydrogen peroxide and incorporation into rain within time periods of hours during summer daytime rains. Rain is an important transport mechanism for removal of atmospheric hydrogen peroxide, which may affect the oxidizing capacity of surface waters that receive the rain. During this study time, the annual deposition of hydrogen peroxide by rain was 12 mmole m-2 yr-1. An average rain event added approximately half of the resident amount of hydrogen peroxide to the shallow lakes typical of eastern North Carolina; extreme rain events can triple the amount normally present. The episodic nature of rain contributes to the variability in hydrogen peroxide concentration in surface waters. Higher hydrogen peroxide concentrations and greater rainfall amounts cause wet deposition of hydrogen peroxide to be approximately seven times greater during the warm season than the cold season.

Does intertidal vegetation indicate specific soil and hydrologic conditions

Abstract: Six distinct plant zones were identified within a mesohaline tidal marsh in the Cape Fear Estuary, North Carolina. USA. All six vegetative zones were found within an 18-cm portion of the 1.35-m tidal range. Aerial photographs show that these six zones have existed within the marsh for the past 20 years. A monotypicJuncus roemerianus stand occupied soils with the highest salinity porewater (17 ppt), while stands dominated (>90%) by eitherScirpus robustus orTypha angustifolia were found associated with the least saline soil water (7 ppt) in areas of the marsh least flooded by tidal waters.Spartina cynosuroides dominated areas of the marsh at lowest elevations. In general, Eh was highest in theJuncus zone and lowest in theSpartina alterniflora zone. Four of the six vegetative zones represented distinct physical and chemical environments and could be statistically separated via canonical discriminate analyses. We suggest that established vegetation may be an accurate analog for specific hydrogeomorphic conditions.

Amnesia Possibly Associated with Zolpidem Administration

Abstract: Two patients experienced amnesia after taking zolpidem 5 and 10 mg. Neither patient could recall telephone conversations that took place within an hour of taking the drug. The first patient placed a call shortly after ingestion; the second took the dose, fell asleep, and was awakened by the call. Health care providers should be aware of the possibility that in some patients, sedative-hypnotic agents such as zolpidem may produce amnesia that begins a short time after ingestion and may persist into the sleep cycle. This may be particularly important in individuals who, after taking a hypnotic agent, may have to make significant decisions that they must be able to remember.

Clinicopathologic factors and patient perceptions associated with surgical breast-conserving treatment

Abstract: Background: Clinical studies have shown equivalent survival rates between breast-conserving surgery (BCS) and mastectomy in early breast cancer; however, rates for BCS remain low. The purpose of this study was to determine (a) the prevalence of BCS in a regional medical center, (b) clinicopathologic factors associated with BCS, and (c) patient perceptions of the treatment decision-making process.

The tourism entrepreneurial process: A conceptualization and implications for research and development

Abstract: Touristic enterprises can significantly contribute to the economic and social well‐being of a community. One practical way to increase the birth of touristic enterprises in a community is to increase the supply of indigenous tourism entrepreneurs. To achieve this quest, it is necessary to determine the touristic enterprise creation process. Once this is accomplished, a community may then develop appropriate policies to stimulate tourism entrepreneurship. This paper presents a conceptualization of the tourism entrepreneurial process including research and management implications.

Teacher disapproval, delinquent peers, and self-reported delinquency: A longitudinal test of labeling theory

Abstract: Data from the National Youth Survey (waves one and two) were used to assess the effects of individual students' perceptions of teacher disapproval on self-reported delinquency. The panel study included youths between the ages of 11 and 17. Consistent with the labeling perspective, the results indicated that perceptions of teacher disapproval are associated with subsequent delinquency. This relationship was significant even when controlling for prior delinquency, thus weakening the argument that labeling is merely a result, and not a cause, of delinquency. The effects did, however, appear to be indirect when measures of delinquent peer associations were included in the model.

Can suspension feeding by bivalves regulate phytoplankton biomass in Lake Waccamaw, North Carolina?

Abstract: Suspension feeding by bivalves has been hypothesized to control phytoplankton biomass in shallow aquatic ecosystems. Lake Waccamaw, North Carolina, USA is a shallow lake with a diverse bivalve assemblage and low to moderate phytoplankton biomass levels. Filtration and ingestion rates of two relatively abundant species in the lake, the endemic unionid, Elliptio waccamawensis, and an introduced species, Corbicula fluminea, were measured in experiments using natural phytoplankton for durations of 1 to 6 days. Measured filtration and ingestion rates averaged 1.78 and 1.121 ind.−1 d−1, much too low to control phytoplankton at the observed phytoplankton biomass levels and growth rates. Measured ingestion rates averaged 4.80 and 1.50 µg chlorophyll a ind.−1 d−1, too low to support individuals of either species. The abundance of benthic microalgae in Lake Waccamaw reaches 200 mg chlorophyll a m−2 in the littoral zone and averages almost an order of magnitude higher than depth-integrated phytoplankton chlorophyll a. Total microalgal biomass in the lake is therefore not controlled by suspension feeding by bivalves.

Asymptotic periodicity in diffusive logistic equations with discrete delays

Abstract: has been the object of intensive analysis by numerous authors [l-6] as a model of single-species population growth. It is known that time delay has a tendency to produce oscillations [2, 5, 61 in (1) which is nonoscillatory when r = 0. In an autonomous delay system modeling two competing species, time delays can even lead to chaotic behavior [4]. If the diffusion is taken into account in the growth rate as well, then time delay may cause random and blow-up effects in the parabolic logistic-delay equation [7]. Nonlinear periodic diffusion equations arise naturally in population models [S-12] where the birth and death rates, rates of diffusion, rates of interaction, and environmental carrying capacities are periodic on a seasonal scale. In this paper we study the following periodicparabolic logistic equation with instantaneous and delay effects duct, x) (3t -Au(t, x) = u(t, x>[a(t, x) m, x)u(t,x)

Labeling and differential association: Towards a general social learning theory of crime and deviance

Abstract: This study contends that components from two theories-labeling and differential association-should be incorporated into a general social learning perspective of crime and deviance. Data from waves one, two, and three of the National Youth Survey (n=1725) are used to test the proposed model. Results indicate that labeling effects are mediated by associations with delinquent peers when looking at a 24-item delinquency index. Theoretical implications and directions for future research are discussed.

Data integrity and the Internet: implications for management

Abstract: The Internet is increasingly used by management professionals to support information gathering and research activities. However, the different sources of information on the Internet (i.e. electronic journals, online databases, messages posted to groups of readers, and e‐mail) must be carefully utilized by the prudent manager. In particular, examines three issues surrounding the use and citation of information received via the Internet. The first issue addresses problems surrounding the accuracy and recency of information obtained on the Internet. The second issue focusses on properly categorizing the type of information received. The last issue examines how to reference properly information obtained from the Internet that is used in academic and industrial research. Concludes with a section on ethical issues related to electronic media.

Coexistence, permanence, and stability in a three species competition model

Abstract: This paper treats a reaction-diffusion system which models the dynamics of three competing species in ecology. A sufficient condition is given to ensure the existence of a positive steady-state solution in terms of the natural growth rates of the competing species. Under the same circumstance, the reaction-diffusion system has a positive global attractor which indicates the permanence effect in the ecological model. The present paper also gives some explicit information on the asymptotic limit of the time-dependent solution in relation to the trivial and semitrivial steady states.

Powwows as Identity Markers: Traditional or Pan-Indian ?

Abstract: This article examines powwows and Indian identity among the Waccamaw Sioux of North Carolina. Data are drawn from structured interviews. The results of our analyses suggest that the salience of powwows to Indian identity rests not in the authenticity of a powwow regarding local history and culture, but rather in the relationship of the activity to popular community participation. Local powwow participation ranks relatively high in importance to Indian identity and is closely associated with more "traditional" community-level identity markers. On the other hand, regional powwow activities rank relatively low in importance to Indian identity and are associated with regional political and administrative aspects of Indian identity. The findings suggest that local powwows have become an important part of traditional Indian identity among the Waccamaw Sioux.