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Field Study (field + study)
Kinds of Field Study Selected AbstractsFIELD STUDY OF ALGAL RECRUITMENT BY CLEARING EXPERIMENT IN PING CHAU, HONG KONG SAR, CHINAJOURNAL OF PHYCOLOGY, Issue 2000S. L. Kong Recruitment, the entry of new individuals into a population, was investigated by a clearing experiment along the shore of A Ma Wan (AMW) in Ping Chau, Hong Kong SAR, China. Two types of clearing, with all the existing vegetation removed (cleared) and with the top 2 to three mm of the rock surface removed (hammered), were carried out monthly in AMW from November 1997 to June 1999. Observations were made one month after clearing and on a monthly basis thereafter. The number of algal species present on the cleared areas and their percentage cover were recorded. The experimental results showed that more algal species were recruited during March and April in 1998 (n=10) but in 1999, the number of species was found higher in February and March (n=8). Species richness dropped after May (more obvious in 1998), indicating that recruitment greatly declined in summer. A tuft complex composed of several filamentous algal species dominated over the others in all clearing areas (coverage mostly over 90%) but recruits of Caulerpa peltata, Colpomenia sinuosa, Enteromorpha sp., Hypnea charoides, Padina spp., Sargassum sp., Spyridia filamentosa, Ulva sp., etc. also were observed during the study period. Generally, there were no significant differences in terms of species richness and composition of the recruits between the two treatments (cleared vs. hammered) as well as with the controls. This implied that algae in AMW were more likely to be recruited de novo from elsewhere rather than regenerated from remnants of the previous year's growth. [source] RECOGNIZING GOOD ATTENDANCE: A LONGITUDINAL, QUASI-EXPERIMENTAL FIELD STUDYPERSONNEL PSYCHOLOGY, Issue 3 2002STEVEN E. MARKHAM Three motivational theories (need, goal, and reinforcement) suggest that recognition programs should increase employee attendance. A 1-year, quasi-experimental field study of absenteeism was conducted at 4 manufacturing plants with a total 1,100 employees. The study compared a public recognition program for improving work attendance with 3 types of controls. The personal recognition treatment showed (a) significant decreases ranging from 29% to 52% for each quarter's baseline assessment, and (b) significant decreases when the control groups showed no decrease. Employees had favorable perceptions of the public recognition program. [source] Lipid-lowering therapy in patients with type 2 diabetes: the case for early interventionDIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 4 2008Armin Steinmetz Abstract Chronic complications of type 2 diabetes, in particular, macrovascular complications, confer substantial morbidity and mortality and adversely affect a patient's quality of life. Early intensive intervention to control cardiovascular risk factors is essential in clinical management. Atherogenic dyslipidaemia characterized by elevated triglycerides, a low level of high-density lipoprotein cholesterol (HDL-C), and an increase in the preponderance of small, dense low-density lipoprotein (LDL) particles, is a key modifiable risk factor for macrovascular diabetic complications. Lowering low-density lipoprotein cholesterol (LDL-C) with a statin (or the combination of statin and ezetimibe) is the main focus for reducing cardiovascular risk in patients with diabetes. However, statins fail to address the residual cardiovascular risk associated with low HDL-C. Fibrates are effective against all components of the atherogenic dyslipidaemia associated with type 2 diabetes. Secondary analyses of the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) study suggest a role for early treatment with fenofibrate in improving cardiovascular risk reduction in type 2 diabetes and provide safety data supporting the use of fenofibrate in combination with a statin. Data from the FIELD study suggest that fenofibrate may also have potential to impact on microvascular diabetic complications associated with type 2 diabetes. Data are awaited from the ongoing Action to Control Cardiovascular Risk in Diabetes (ACCORD) study to evaluate the outcome benefits of combining fenofibrate with a statin in patients with type 2 diabetes. Finally, in view of divergent study results and outstanding data, assessment of the risk of the individual with type 2 diabetes is mandatory to assist clinical decision-making when initiating lipid therapy. Copyright © 2008 John Wiley & Sons, Ltd. [source] Monitored Natural Attenuation of Manufactured Gas Plant Tar Mono- and Polycyclic Aromatic Hydrocarbons in Ground Water: A 14-Year Field StudyGROUND WATER MONITORING & REMEDIATION, Issue 3 2009Edward F. Neuhauser Site 24 was the subject of a 14-year (5110-day) study of a ground water plume created by the disposal of manufactured gas plant (MGP) tar into a shallow sandy aquifer approximately 25 years prior to the study. The ground water plume in 1988 extended from a well-defined source area to a distance of approximately 400 m down gradient. A system of monitoring wells was installed along six transects that ran perpendicular to the longitudinal axis of the plume centerline. The MGP tar source was removed from the site in 1991 and a 14-year ground water monitored natural attenuation (MNA) study commenced. The program measured the dissolved mono- and polycyclic aromatic hydrocarbons (MAHs and PAHs) periodically over time, which decreased significantly over the 14-year period. Naphthalene decreased to less than 99% of the original dissolved mass, with mass degradation rates of 0.30 per year (half-life 2.3 years). Bulk attenuation rate constants for plume centerline concentrations over time ranged from 0.33 ± 0.09 per year (half-life 2.3 ± 0.8 years) for toluene and 0.45 ± 0.06 per year (half-life 1.6 ± 0.2 years) for naphthalene. The hydrogeologic setting at Site 24, having a sandy aquifer, shallow water table, clay confining layer, and aerobic conditions, was ideal for demonstrating MNA. However, these results demonstrate that MNA is a viable remedial strategy for ground water at sites impacted by MAHs and PAHs after the original source is removed, stabilized, or contained. [source] Self-Monitoring and Performance Appraisal Satisfaction: An Exploratory Field StudyHUMAN RESOURCE MANAGEMENT, Issue 4 2001Janice S. Miller Members of 12 project teams in five organizations participated in a study that assessed their self-monitoring characteristics and level of satisfaction with their performance appraisal system. Overall, taking part in self-ratings and upward appraisals of team leaders was associated with greater levels of appraisal satisfaction than was participating in peer evaluations. Self-monitoring level was negatively associated with appraisal satisfaction after controlling for level of ratings generated by peers, self, and leader. The paper discusses results, and offers practical implications in light of the social and interpersonal context that surrounds performance evaluation. © 2001 John Wiley & Sons, Inc. [source] Performance Impact of the Elimination of Direct Labor Variance Reporting: A Field StudyJOURNAL OF ACCOUNTING RESEARCH, Issue 4 2002Rajiv D. Banker Using a field study approach, we examine two competing perspectives on direct labor variance reporting: some argue that direct labor variance reporting is costly and cumbersome, and should be eliminated; whereas others contend that without direct labor variance information, managers will not be able to monitor workers effectively, causing workers to shirk and worker productivity to decline. Specifically, we investigate the productivity and quality impacts of eliminating direct labor variance reporting with panel data containing 36 months of data from seven experimental plants that eliminated direct labor variance reporting and 11 control plants that did not. The experimental plants experienced a significant decline in labor productivity compared to the control plants. Also, the experimental plants showed an improvement in product quality, indicating that workers reallocate their efforts to other tasks as a result of the change in the information set available to evaluate them. [source] Structural Solutions to Social Dilemmas: A Field Study on Commuters' Willingness to Fund Improvements in Public Transit,JOURNAL OF APPLIED SOCIAL PSYCHOLOGY, Issue 3 2001Jeffrey A. Joireman The present field study examined commuters'(N= 152) willingness to fund improvements in public transit. Consistent with Samuelson's (1993; Samuelson & Messick, 1995) multiattribute evaluation model of structural change in social dilemmas, support for the transit plan was higher when it was perceived to be (a) effective at reducing congestion and pollution, (b) personally beneficial, and (c) fair in terms of taxes and benefits. Also consistent with predictions, these relationships were moderated by individual differences in social value orientation (MClintock, 1968) and the consideration of future consequences (CFC; Strathman, Gleicher, Boninger, & Edwards, 1994). Prosocials responded more to the perceived fairness of the plan, while proselfs responded more to the plan's effectiveness in reducing congestion. Low CFCs responded more to the plan's personal benefits and effectiveness in reducing congestion, while high CFCs responded more to the plan's effectiveness in reducing pollution. [source] The Impact of Activity-Based Costing on Managerial Decisions at Insteel Industries,A Field StudyJOURNAL OF ECONOMICS & MANAGEMENT STRATEGY, Issue 2 2002V.G. Narayanan In this field-based study, we interview top- and middle-level managers at Insteel Industries and conduct statistical analysis of firm-level data in order to shed light on whether activity-based costing (ABC) provides new information to managers and whether activity-based management (ABM) significantly influences product and customer-related decisions. We find that after the ABC analysis, Insteel undertook a number of process improvements that resulted in significant cost savings. Additionally, Insteel displayed a higher propensity to discontinue or increase prices of products and discontinue customers that were found comparatively unprofitable in the ABC study. Thus we provide empirical evidence that ABC influences both strategic and operational managerial decisions. [source] Inconsistencies Between Actual and Estimated Blood Alcohol Concentrations in a Field Study of College Students: Do Students Really Know How Much They Drink?ALCOHOLISM, Issue 9 2005Courtney L. Kraus Background: Alcohol use by college students is commonly measured through the use of surveys. The validity of such data hinge on the assumption that students are aware of how much alcohol they actually consume. Recent studies call this assumption into question. Students tend to overestimate the appropriate sizes of standard drinks, suggesting that they might underestimate how much alcohol they consume. If this is true, then students' actual blood alcohol concentrations (BACs) should be higher than BACs estimated based on self-report data. The present study examined this issue Methods: Breathalyzer readings and self-reported drinking data were collected from 152 college students during the fall of 2004. Estimated BACs were calculated by means of a standard formula, and the relation between actual and estimated BACs was examined. Factors contributing to discrepancies between the two values were identified Results: Estimated BAC levels were significantly higher, not lower, than breath BAC measures. The accuracy of estimated BACs decreased as the number of drinks and amount of time spent drinking increased. Being male and drinking only beer predicted greater accuracy of estimated BACs Conclusions: Although laboratory data suggest that students underestimate how much they drink, the hypothesis was not supported by data collected in the field. It appears that students might actually overestimate rather than underestimate their levels of consumption when surveyed in the midst of a night of drinking. The findings corroborate observations made by other researchers and suggest that the findings of laboratory studies on college drinking do not necessarily extend to real-world settings. [source] Toward a Theory of Performance Reporting to Achieve Public Sector Accountability: A Field StudyPUBLIC BUDGETING AND FINANCE, Issue 2 2005Gary M. Cunningham Governments in many countries are implementing performance reporting systems. Many advocates claim that performance reporting results in accountability and effectiveness. There is no theory to justify these claims and guide implementation. This paper presents five field studies of five performance-reporting systems to begin building theory. Four locations are optimistic; one is not. Mere adoption of performance reporting is not effective. Broad involvement across all government levels is important. Communication and integration with strategic planning and agency management are essential. Two theoretical streams, accounting in organized anarchies and the constitutive role of accounting, are useful theoretical bases. [source] Macronutrient Regulation in the Tropical Terrestrial Ant Ectatomma ruidum (Formicidae): A Field Study in Costa RicaBIOTROPICA, Issue 2 2010Steven C. Cook ABSTRACT Using the geometric framework for the first time in a field study of ant nutritional biology, we show that Ectatomma ruidum colonies actively regulate protein,carbohydrate intake, self-selecting a carbohydrate-biased diet. These data, combined with quantitative recruitment data, provide a more comprehensive understanding of colony-level nutritional requirements of ants. Abstract in Spanish is available at http://www.blackwell-synergy.com/loi/btp [source] Malformation of True Bug (Heteroptera): a Phenotype Field Study on the Possible Influence of Artificial Low-Level RadioactivityCHEMISTRY & BIODIVERSITY, Issue 4 2008Cornelia Hesse-Honegger Abstract The results of extensive field studies on the malformation of Western European true bugs (Heteroptera) are reviewed. More than 16,000 individuals were collected over two decades, and subjected to detailed visual inspection. Various types of disturbances were found and illustrated in detail. Depending on country, region, as well as local influences, severe disturbances and high degrees of malformation were noticed, especially in the sphere of nuclear-power installations in Switzerland (Aargau), France (La Hague), and Germany (Gundremmingen). Malformation reached values as high as 22 and 30% for morphological (MD) and total disturbance (TD), respectively. This is far above the values expected for natural populations (ca. 1%) or those determined for true bugs living in biotopes considered as relatively ,intact' (1,3%). A detailed chi-square test of the malformation data obtained for 650 true bugs from 13 collection sites near the nuclear-reprocessing plant La Hague showed a highly significant correlation (p=0.003) between malformation and wind exposure/local topography. Similar observations were made for other study sites. Currently, our data are best rationalized by assuming a direct influence between the release of anthropogenic radionuclides such as tritium (3H), carbon-14 (14C), or iodine-131 (131I), constantly emitted by nuclear-power and nuclear-reprocessing plants, as well as by Chernobyl and bomb-testing fallout, which is rich in caesium-137 (137Cs) and other long-lived noxious isotopes that have entered the food chain. The present work supports the growing evidence that low-level radiation, especially in the form of randomly scattered ,hot' , - and , -particles, mainly transported via aerosols, puts a heavy burden on the biosphere in general, and on true bugs in particular. These insects could, thus, serve as sensitive ,bio-indicators' for future studies. [source] Toxicity and chemistry of aspen wood leachate to aquatic life: Field studyENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2003Barry R. Taylor Abstract A dark, toxic leachate has been observed around woodpiles of trembling aspen (Populus tremuloides Michx.) cut in winter for pulp or structural lumber. We measured production of leachate from 18 m3 of harvestable aspen logs stacked in an open field near Dawson Creek, British Columbia, Canada. The logpile began producing leachate during the first winter thaw and continued to do so for the duration of the two-year study (mean, 250 L/collection). Aspen leachate was characterized by dark color, acidic pH (5.0-6.5), elevated conductivity (200-500 ,S/cm), high to very high biochemical oxygen demand (500-5,000 mg/L) and total organic carbon concentrations (500-2,000 mg/L), variable levels of phenolic compounds (2-27 mg/L), and low dissolved oxygen tensions (<2 mg/L). In tests with rainbow trout (Oncorhynchus mykiss), Daphnia magna, and luminescent bacteria, the leachate varied from weakly toxic (median lethal concentration, >10%) to very toxic (median lethal concentration, <1%). The volume of leachate generated by the logpile was correlated with total precipitation (rain or snow) since the last collection. Loads of chemical constituents or toxicity (lethal concentration × volume) in the leachate did not decline over the duration of the study. Less than 10% of the total mass of leachable material in the aspen logs was removed during two years of exposure. [source] Field study on superheater tubes in the loop seal of a wood fired CFB plantMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 12 2004A. Nafari Abstract Two full scale superheaters were exposed in the loop seal of a 30 MW wood-fired CFB plant in Nässjö, Sweden, for one firing season each. Some austenitic steel tubes from the first tube bundle were reinstalled in the second superheater. The superheater tubes were made from one ferritic steel, X10 (Fe8.8Cr) and three austenitic steels; Esshete 1250 (Fe15Cr9Ni6Mn), 347H (Fe17Cr11Ni) and AC66 (Fe27Cr32Ni). Commercial coatings mainly on iron, nickel and carbide base were deposited on some of the X10 and 347H tubes. The material wastage kinetics was non-linear showing that pure corrosion and not erosion-corrosion is the major degradation mechanism in the loop seal. It is however clear that the environment is not very aggressive and the corrosion attack on the uncoated tubes is very small. The largest oxide thickness was only about 150 ,m recorded on the X10 alloy. The austenitic steels mainly suffered from internal corrosion and grain boundary corrosion, the extent and distribution of which strongly depended on the alloy composition. Generally, it was more pronounced in the regions with the thinnest deposit layers. Eight out of 17 coating qualities tested were unaffected by the exposure. Corrosion was only recorded on the lowest alloyed iron based coatings. The only coatings which could not resist the conditions in the loop seal were the carbide containing Metco 3006 and Metco 3007, where severe oxidation and delamination took place. Also the thermally sprayed Inconel 625 coating delaminated, but this was rather due to a mechanical failure resulting from thermal expansion. [source] The Difficult Client-Acceptance Decision in Canadian Audit Firms: A Field Investigation,CONTEMPORARY ACCOUNTING RESEARCH, Issue 2 2001Yves Gendron Abstract Auditing is often depicted in scientific and professional literature as being subject to conflicting forces, such as mechanization versus flexibility, and professionalism versus commercialism. This paper examines how auditors actually make the client-acceptance decision in the midst of these forces. The investigation was conducted via a field study at three Big 6 firms located in Canada. The results show that in all firms the client-acceptance decision process in action is largely flexible, being characterized by a high degree of informal communication and the adaptation of the client-acceptance written policies and decision aids to circumstances. Furthermore, while commercialism in one firm (A) has a significant influence on the decision process, in the two other firms (B and C) the decision process is mostly consistent with professionalism. This result conflicts with the concerns that North American regulators have recently expressed about auditors' professionalism. [source] Factors Associated with Creative Strategic DecisionsCREATIVITY AND INNOVATION MANAGEMENT, Issue 3 2008Cameron M. Ford The study and practice of business strategy is fundamentally based on employing creative solutions to differentiate a firm from its competitors. Theories used to describe the causes and consequences of strategic differentiation tend to focus on organization-level characteristics such as resources, capabilities and structures. However, less is known about day-to-day processes and practices whereby strategic managers develop create solutions necessary to establish strategic differentiation. This paper presents a preliminary field study of factors suggested by previous strategy process and micro-strategy research that may lead to, and result from, creative strategic decisions. Findings produced by a longitudinal field study of 52 strategic decisions reveal that creative strategic choices arise in response to managers' perceptions of uncertainty and competition. The findings also suggest that creativity may improve the ultimate effectiveness of strategic choices by 5,10 per cent. [source] Payments for Ecosystem Services in Nicaragua: Do Market-based Approaches Work?DEVELOPMENT AND CHANGE, Issue 3 2010Gert Van Hecken ABSTRACT The concept of Payments for Ecosystem Services (PES) is gaining increasing attention among scholars as well as conservation and development practitioners. The premises of this innovative conservation approach are appealing: private land users, usually poorly motivated to protect nature on their land, will do so if they receive payments from environmental service buyers which cover part of the land users' opportunity costs of developing the land. However, this article warns against an over-enthusiastic adoption of a one-sided market-based PES approach. Based on a field study of the Regional Integrated Silvopastoral Approaches to Ecosystem Management Project (RISEMP), one of the main PES pilot projects in Nicaragua, it suggests that a mixture of economic and non-economic factors motivated farmers to adopt the envisaged silvopastoral practices and that the actual role of PES is mistakenly understood as a simple matter of financial incentives. The authors argue that PES approaches should be understood as a part of a broader process of local institutional transformation rather than as a market-based alternative for allegedly ineffective government and/or community governance. [source] Oviposition decreased in response to enriched water: a field study of the pitcher-plant mosquito, Wyeomyia smithiiECOLOGICAL ENTOMOLOGY, Issue 1 2007DAVID HOEKMAN Abstract 1.,Environmental cues are known to influence oviposition behaviour in mosquitoes, with important consequences for larval survival and insect population dynamics. Enriched microhabitats have been shown to be preferred oviposition sites. 2.,In a field experiment designed to determine whether ovipositing mosquitoes are sensitive to different levels of nutrient enrichment, new pitcher-plant (Sarracenia purpurea) leaves were opened and enriched with 0, 2, or 20 dead ants, and the number of pitcher-plant mosquito (Wyeomyia smithii) larvae resulting from subsequent oviposition were measured. 3.,Oviposition rates were higher in leaves with low levels of enrichment (0 and 2 ants per leaf), although larval development was enhanced at the highest enrichment level. 4.,Results suggest that, although these mosquito larvae are nutrient limited, ovipositing females preferentially avoid highly enriched leaves. This counterintuitive result may be due to low oxygen concentrations or a masked cue in enriched leaves, and contrasts with other oviposition studies. [source] Evolution in ecological field experiments: implications for effect sizeECOLOGY LETTERS, Issue 3 2008Sharon Y. Strauss Abstract Rapid evolution in response to strong selection, much of which is human-induced, has been indisputably documented. In this perspective, we suggest that adaptation may influence the effect size of treatments in ecological field experiments and alter our predictions of future dynamics in ecological systems. Field experiments often impose very strong and consistent selection over multiple generations. Focal populations may adapt to these treatments and, in the process, increase or decrease the magnitude of the treatment effect through time. We argue that how effect size changes through time will depend on the evolutionary history of the experimental population, the type of experimental manipulation, and the traits involved in adaptive responses. While no field study has conclusively demonstrated evolution in response to treatments with concomitant changes in ecological effect size, we present several examples that provide strong circumstantial evidence that such effects occur. We conclude with a consideration of the differences between plastic and genetic responses to treatments and discuss future research directions linking adaptation to ecological effect size. [source] Rare species loss alters ecosystem function , invasion resistanceECOLOGY LETTERS, Issue 4 2001Kelly G. Lyons The imminent decline in species diversity coupled with increasing exotic species introductions has provoked investigation into the role of resident diversity in community resistance to exotic species colonization. Here we present the results of a field study using an experimental method in which diversity was altered by removal of less abundant species and the resulting disturbance was controlled for by removal of an equivalent amount of biomass of the most common species from paired plots. Following these manipulations, the exotic grass, Lolium temulentum, was introduced. We found that exotic species establishment was higher in plots in which diversity was successfully reduced by removal treatments and was inversely related to imposed species richness. These results demonstrate that less common species can significantly influence invasion events and highlight the potential role of less common species in the maintenance of ecosystem function. [source] Strategic Use of Corporate VenturingENTREPRENEURSHIP THEORY AND PRACTICE, Issue 2 2007Jeffrey G. Covin Corporate venturing (CV) is said to be most productive as a path to superior corporate performance when practiced in a strategic manner. Unfortunately, considerable ambiguity exists concerning what it means in an organizational practice sense to strategically pursue CV. The result is a failure of many companies to fully leverage CV for strategic purposes. Based on a review of the CV literature and findings from a field study of 15 Swedish, U.K., and U.S. corporations, this article describes several models that depict the ways in which CV and business strategy coexist as organizational phenomena. Empirically derived propositions are offered to suggest how some companies are strategically engaged in their CV efforts. [source] Indoor air temperatures and energy use: A comparative field study of vernacular, conventional, and alternative-technology construction in IndiaENVIRONMENTAL QUALITY MANAGEMENT, Issue 4 2010Lekha S. Hegde First page of article [source] Dissipation kinetics and mobility of chlortetracycline, tylosin, and monensin in an agricultural soil in Northumberland County, Ontario, CanadaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2006Jules C. Carlson Abstract A robust high-throughput method was refined to extract three growth-promoting antibiotics, tylosin (TYL), chlortetracycline (CTC), and monensin (MON), from soil. Analysis was performed by electrospray liquid chromatography tandem mass spectrometry. Soil dissipation rate studies were performed in a farm field soil for antibiotics applied with and without manure. Tylosin, CTC, and MON followed first-order dissipation kinetics with half-lives of 4.5, 24, and 3.3 d, respectively, with the addition of manure and 6.1, 21, and 3.8 d, respectively, without manure. Manure application significantly increased TYL dissipation rate, perhaps because of the introduced microbial flora, but had no significant effect on CTC or MON. Monensin dissipation half-life was found to be much shorter in the field study than in a controlled laboratory study, perhaps because of differences in microbial communities. The antimicrobials were not highly mobile. Chlortetracycline was the only antibiotic detected at 25 to 35 cm depth and only up to 2% of the initial concentration in a sandy loam soil. These antibiotics are therefore expected to degrade primarily in agricultural soils before moving to greater depths or to groundwater in significant concentrations in most agricultural systems. [source] In situ reproduction, abundance, and growth of young-of-year and adult largemouth bass in a population exposed to polychlorinated biphenylsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2004Dudley W. Reiser Abstract We conducted a two-year field study (2000,2001) in the Housatonic River, Massachusetts (USA) to determine if we could detect in situ population-level effects on largemouth bass (Micropterus salmoides) exposed to elevated levels of polychlorinated biphenyls (PCBs). Calculated whole-body PCB concentrations in adult bass in 2002 averaged 121 mg/kg (range = 34,556 mg/kg). Polychlorinated biphenyl concentrations in young-of-year (YOY) composites in 2000 and 2002 averaged 28 mg/kg (range = 21,41 mg/kg) and 19 mg/kg (range = 16,24 mg/kg), respectively. Laboratory studies of fish have reported PCB toxicity at exposure levels below and within the range of those found in the Housatonic River. We evaluated five field-derived metrics: reproductive activity, relative abundance of YOY, YOY growth rates, adult growth, and adult condition to determine whether we could detect effects of PCBs in the largemouth bass population. These computed metrics, when compared with data sets assembled for numerous largemouth bass populations in North America, provided no evidence of population-level impairment. Results of this study suggest that PCB tissue concentrations associated with effects in laboratory studies do not necessarily translate to detectable effects on largemouth bass populations in their natural environment. [source] Immunosuppression in the northern leopard frog (Rana pipiens) induced by pesticide exposureENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2003Mary-Kate Gilbertson Abstract An injection study and a field study were used to investigate the hypothesis that environmental xenobiotics have the potential to alter the immune function of northern leopard frogs (Rana pipiens). Three assays, IgM-specific antibody response to keyhole limpet hemocyanin linked to dinitrophenyl (KLH-DNP), zymozan induced chemiluminescence (CL) of whole blood and the delayed-type hypersensitivity (DTH), were used to assay humoral, innate and cell-mediated immune endpoints. Sublethal doses of DDT (923 ng/g wet wt), malathion (990 ng/g wet wt), and dieldrin (50 ng/g wet wt) were used in the injection study. In all pesticide-injected groups, antibody response was dramatically suppressed, DTH reactions were enhanced, and respiratory burst was lower. When the order of administration of pesticides and antigens was reversed, no differences in immune function between the control and dosed groups were apparent, indicating that frogs exposed to pathogens prior to pesticide exposure can still respond. A field study found significant differences in immune function between frog populations in pesticide-exposed and pesticide-free locations. The antibody response and CL were suppressed and the DTH enhanced in frogs from Essex County (ON, Canada). Overall, the results suggest that exposure to these pesticides can cause both stimulatory and suppressive immune changes in adult frogs and is doing so in wild populations. [source] Localization of deposited polycyclic aromatic hydrocarbons in leaves of PlantagoENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2001Martine I. Bakker Abstract After deposition to foliage, polycyclic aromatic hydrocarbons (PAHs) may remain on the leaf surface, accumulate in the cuticular wax, or diffuse into the remaining interior of the plant. In a field study, the location of deposited PAHs in the leaves of two Plantago species was determined. To this aim, leaves of Plantago major and Plantago media were divided into three fractions. First, the leaves were washed (wash-off fraction), then cuticular wax was extracted (wax fraction). Finally, the remaining leaf material was extracted (interior fraction). The presence of PAHs could be demonstrated in all three fractions. For both plants, the distribution of PAHs over the three fractions changed with molecular weight (mol wt) of the PAHs. The wash-off fraction increased with increasing molecular weight, likely because high molecular-weight PAHs occur predominantly bound to particles, which can be readily washed off from the leaves. In contrast, the amount of PAHs detected in the interior of the leaves decreased with increasing molecular weight. This can be explained by a slow desorption of the PAHs from the particles and a low diffusion rate of the larger molecules. This study shows that washing reduces the amount of high molecular-weight PAHs on plant surfaces. Therefore, washing of leafy vegetables is important to minimize human dietary intake of PAHs. [source] Response of zooplankton communities to liquid creosote in freshwater microcosmsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2001Paul K. Sibley Abstract In this study, the response of zooplankton communities to single applications of liquid creosote in model aquatic ecosystems (microcosms) was evaluated. Liquid creosote was applied to 14 microcosms at concentrations ranging from 0.06 to 109 mg/L. Two microcosms served as controls. Zooplankton samples were collected from each microcosm on days 7 and 1 before treatment and on days 2, 5, 7, 14, 21, 28, 43, 55, and 83 following treatment. Temporal changes (response-recovery) in composition of the zooplankton community were assessed using principal response curves (PRC). Creosote induced a rapid, concentrationdependent reduction in zooplankton abundance and number of taxa, with maximum response (50,100% reduction in population densities) occurring between 5 and 7 d after treatment. Taxa that dominated at the time of treatment experienced the greatest impact, as indicated by large, positive species weight values (>1) from the PRC analysis. Many of these taxa recovered to pretreatment or control levels during the posttreatment period, with the degree and duration of recovery being strongly dependent on concentration. Creosote had little effect on species composition at less than 1.1 mg/L, because changes in the types and relative proportion of species contributed from Cladocera, Rotifera, and Copepoda were comparable to those observed in control microcosms. However, a significant shift in species composition was observed at concentrations greater than 1.1 mg/L; these microcosms were generally dominated by low numbers of rotifers, some of which had not been collected before treatment. Community-level effect concentrations (EC50s) were 44.6 and 46.6 ,g/L at 5 and 7 d, respectively, based on nominal creosote. Corresponding no-effect concentrations were 13.9 and 5.6 ,g/L. The results of this field study indicate that creosote may pose a significant risk to zooplankton communities at environmental concentrations potentially encountered during spills and/or leaching events. [source] The Effect of Within-Flock Spatial Position on the Use of Social Foraging Tactics in Free-Living Tree SparrowsETHOLOGY, Issue 3 2008Ferenc Mónus The benefit of producer (searches for own food) or scrounger (exploits the others' food discoveries) foraging tactic in a group of socially feeding animals may depend on where the individual searches for food within the group. Scrounging may be more advantageous in the centre of the group, having more individuals around to join, while producing may be more beneficial at the edges, where more unexplored food patches may be found. This study shows within-flock position correlates with foraging tactic use of feeding birds in socially foraging tree sparrows, Passer montanus. Sparrows staying closer to the centre of the flock found their food patches more frequently by joining (i.e. use more frequently the scrounging tactic) than those staying toward the edges. To our knowledge this is the first field study demonstrating the relationship between spatial position and foraging tactic use. We investigated this relationship under different perceived predation hazard, and found that under elevated risk of predation, central individuals may increase their use of joining more than individuals on the periphery of the flock. Moreover, we show that extremely specialized use of searching tactics may be very infrequent in tree sparrows. As both within-flock position and search tactic use can be altered very quickly and without leaving the flock, individuals may easily alter them in order to adjust their behaviour. [source] Distress, Dissociation, and Embodied Experience: Reconsidering the Pathways to Mediumship and Mental HealthETHOS, Issue 1 2005REBECCA SELIGMAN This article explores the biocultural bases of spirit possession mediumship in the Afro-Brazilian religion, Candomblé. After a brief review of the literature, the article moves beyond the biomedical and social-structural explanations that have dominated the theoretical landscape, by attempting to construct an etiology of mediumship that is traced through the interface of individual characteristics with the cultural belief system that forms their context. Data were collected from a total of 71 individuals over the course of a year-long field study in Salvador, Brazil. Analyses of social ethnography, life history and semistructured interviews along with results from psychological inventories, suggest that altered states of consciousness should not be considered the central and defining element of mediumship. An alternative model is proposed, in which the combination of social conditions and somatic susceptibilities causes certain individuals to identify with the mediumship role, and predisposes them to dissociate. However in the context of Candomblé, dissociation is not a pathological experience, but rather a therapeutic mechanism, learned through religious participation, that benefits individuals with a strong tendency to somatize. [source] The personality basis of justice: The five-factor model as an integrative model of personality and procedural fairness effects on cooperationEUROPEAN JOURNAL OF PERSONALITY, Issue 6 2008Alain Van Hiel Abstract Building upon the self-based model of cooperation (De Cremer & Tyler, 2005), the present study investigates the relationship between the five-factor model (FFM) and cooperation. Study 1 (N,=,56), an experiment conducted in the laboratory, and Study 2 (N,=,116), a field study conducted in an organisational context, yielded a moderator effect between neuroticism and procedural fairness in explaining cooperation. Study 3 (N,=,177) showed that this moderator effect was mediated by the self-uncertainty and relational variables proposed by the self-based model of cooperation. It is concluded that the FFM is useful in explaining cooperation and contributes to a better understanding of (procedural) fairness effects. Moreover, the necessity to build integrative, multi-level models that combine core and surface aspects of personality to explain the effects of fairness on cooperation is elaborated upon. Copyright © 2008 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||