1,906 research outputs found
Population response of triploid grass carp to declining levels of hydrilla in the Santee Cooper Reservoirs, South Carolina
Approximately 768,500 triploid grass carp (
Ctenopharyngodon
idella
Valenciennes) were stocked into the Santee Cooper
reservoirs, South Carolina between 1989 and 1996 to
control hydrilla (
Hydrilla verticillata
(L.f.) Royle). Hydrilla
coverage was reduced from a high of 17,272 ha during 1994
to a few ha by 1998. During 1997, 1998 and 1999, at least 98
triploid grass carp were collected yearly for population monitoring.
Estimates of age, growth, and mortality, as well as
population models, were used in the study to monitor triploid
grass carp and predict population trends. Condition declined
from that measured during a previous study in 1994.
The annual mortality rate was estimated at 28% in 1997, 32%
in 1998 and 39% in 1999; however, only the 1999 mortality
rate was significantly different. Few (2 out of 98) of the triploid
grass carp collected during 1999 were older than age 9.
We expect increased mortality due to an aging population
and sparse hydrilla coverage. During 1999, we estimated about
63,000 triploid grass carp system wide and project less than
3,000 fish by 2004, assuming no future stocking.
management, population size
Ctenopharyngodon idella, Hydrill
Perfectionism and self-conscious emotions in British and Japanese students: Predicting pride and embarrassment after success and failure
Regarding self-conscious emotions, studies have shown that different forms of perfectionism show different relationships with pride, shame, and embarrassment depending on success and failure. What is unknown is whether these relationships also show cultural variations. Therefore, we conducted a study investigating how self-oriented and socially prescribed perfectionism predicted pride and embarrassment after success and failure comparing 363 British and 352 Japanese students. Students were asked to respond to a set of scenarios where they imagined achieving either perfect (success) or flawed results (failure). In both British and Japanese students, self-oriented perfectionism positively predicted pride after success and embarrassment after failure whereas socially prescribed perfectionism predicted embarrassment after success and failure. Moreover, in Japanese students, socially prescribed perfectionism positively predicted pride after success and self-oriented perfectionism negatively predicted pride after failure. The findings have implications for our understanding of perfectionism indicating that the perfectionismāpride relationship not only varies between perfectionism dimensions, but may also show cultural variations
Social support moderates the relationship between stressors and task performance through self-efficacy
This study examined the relationship between social support and objective task performance in a field setting. A sample of 197 participants, mean age 23.13 years (SD 3.56) completed measures of stressors, social support, and self-efficacy prior to performance. Moderated hierarchical regression analysis revealed significant(p < .05) main effects for stressors (R2 = .12) and social support (ĪR2 = .14) in relation to performance, in the hypothesized directions. A significant interaction (ĪR2 = .06) suggested that social support moderated (buffered) the relationship between stressors and task performance. Moderated mediation analysis demonstrated that social support was associated with increases in self-efficacy, and self-efficacy was associated with enhanced performance, but that this effect was only salient at moderate to high levels of stressors
Chronic stress and age-related increases in the proinflammatory cytokine IL-6
Overproduction of IL-6, a proinflammatory cytokine, is associated with a spectrum of age-related conditions including cardiovascular disease, osteoporosis, arthritis, type 2 diabetes, certain cancers, periodontal disease, frailty, and functional decline. To describe the pattern of change in IL-6 over 6 years among older adults undergoing a chronic stressor, this longitudinal community study assessed the relationship between chronic stress and IL-6 production in 119 men and women who were caregiving for a spouse with dementia and 106 noncaregivers, with a mean age at study entry of 70.58 (SD = 8.03) for the full sample. On entry into this portion of the longitudinal study, 28 of the caregivers' spouses had already died, and an additional 50 of the 119 spouses died during the 6 years of this study. Levels of IL-6 and health behaviors associated with IL-6 were measured across 6 years. Caregivers' average rate of increase in IL-6 was about four times as large as that of noncaregivers. Moreover, the mean annual changes in IL-6 among former caregivers did not differ from that of current caregivers even several years after the death of the impaired spouse. There were no systematic group differences in chronic health problems, medications, or health-relevant behaviors that might have accounted for caregivers' steeper IL-6 slope. These data provide evidence of a key mechanism through which chronic stressors may accelerate risk of a host of age-related diseases by prematurely aging the immune response
Signaling in Secret: Pay-for-Performance and the Incentive and Sorting Effects of Pay Secrecy
Key Findings: Pay secrecy adversely impacts individual task performance because it weakens the perception that an increase in performance will be accompanied by increase in pay; Pay secrecy is associated with a decrease in employee performance and retention in pay-for-performance systems, which measure performance using relative (i.e., peer-ranked) criteria rather than an absolute scale (see Figure 2 on page 5); High performing employees tend to be most sensitive to negative pay-for- performance perceptions; There are many signals embedded within HR policies and practices, which can influence employeesā perception of workplace uncertainty/inequity and impact their performance and turnover intentions; and When pay transparency is impractical, organizations may benefit from introducing partial pay openness to mitigate these effects on employee performance and retention
Ethnic diversity as a multilevel construct:the combined effects of dissimilarity, group diversity, and societal status on learning performance in work groups
The authors present a model of the multilevel effects of diversity on individual learning performance in work groups. For ethnically diverse work groups, the model predicts that group diversity elicits either positive or negative effects on individual learning performance, depending on whether a focal individualās ethnic dissimilarity from other group members is high or low. By further considering the societal status of an individualās ethnic origin within society (Anglo versus non-Anglo for our U.K. context), the authors hypothesize that the modelās predictions hold more strongly for non-Anglo group members than for Anglo group members. We test this model with data from 412 individuals working on a 24-week business simulation in 87 four- to seven-person groups with varying degrees of ethnic diversity. Two of the three hypotheses derived from the model received full support and one hypothesis received partial support. Implications for theory development, methods, and practice in applied group diversity research are discussed
Speech difficulties and patient health communication mediating effects on worry and healthārelated quality of life in children, adolescents, and young adults with Neurofibromatosis Type 1
The objective was to investigate the serial mediating effects of speech difficulties, patient health communication, and diseaseāspecific worry in the relationship between neurofibromatosis (NF) symptoms (pain and skin symptoms) and total generic healthārelated quality of life (HRQOL) in children, adolescents, and young adults with NF Type 1 (NF1) from the patient perspective. The Speech, Communication, Worry, Pain, Skin Itch Bother, and Skin Sensations Scales from the Pediatric Quality of Life Inventory (PedsQL) NF1 Module and the PedsQL 4.0 Generic Core Scales were completed in a multiāsite national study by 305 patients ages 5ā25āyears. A serial multiple mediator model analysis was conducted to test the hypothesized sequential mediating effects of speech difficulties, health communication, and worry as intervening variables in the association between NF1 symptoms and HRQOL. Symptoms predictive effects on total generic HRQOL were serially mediated by speech difficulties, patient health communication, and worry. In predictive analytics models utilizing hierarchical multiple regression analyses with age and gender demographic covariates, the pain, skin itch bother, and skin sensations multiple mediator models accounted for 61%, 59%, and 56% of the variance in generic HRQOL (pā<ā.001), reflecting large effect sizes. Speech difficulties, patient health communication, and diseaseāspecific worry explain in part the mechanism of symptoms predictive effects on total generic HRQOL in pediatric patients with NF1. Identifying NF1āspecific predictors and serial mediators of total generic HRQOL in pediatric patients with NF1 from the patient perspective enables a patientācentered comprehensive care approach for children, adolescents, and young adults with NF1
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