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341.
Kevin A. Whitehead Andrew T. Ainsworth Michele A. Wittig Brandy Gadino 《Journal of research on adolescence》2009,19(1):123-135
The present paper develops and tests two temporal models of the relationships among adolescents' ethnic identity exploration, ethnic identity affirmation and belonging, and attitudes toward their racial/ethnic ingroup and outgroups. Structural equation models for Euro‐Americans, Asian Americans, and Latinos revealed that all hypothesized relationships were positive and significant. The model in which ethnic identity exploration (at Time 1) predicts ethnic identity affirmation and belonging (at Time 2) was superior to the alternative model in which the relationship between them was reversed (i.e., affirmation and belonging at Time 1 predicts exploration at Time 2). Results (1) support the importance of exploration as a basis for establishing a secure attachment to one's ethnic identity, which, in turn, has positive implications for attitudes toward one's own group and other groups and (2) suggest that maintenance of ethnic identity is compatible with positive attitudes toward ethnic outgroups. 相似文献
342.
Urbanization and development are predicted to increase considerably in the United States over the next several decades, and
this is expected to result in large-scale habitat loss, fragmentation and loss of wildlife species. Thus, natural parks and
preserves are becomingly increasingly important in the conservation of regional biodiversity. We used mist-nets and AnabatII
acoustic detectors to survey bats in 10 national parks in the southeastern U.S. and examined the relationship between bat
community structure and development in the surrounding 5 km. We predicted that species richness would increase with park size
and that species richness and evenness would decrease with development. Species richness was not related to development or
any other landscape characteristics including park size. In contrast, species evenness declined with increasing development.
Percent Developed land in the surrounding 5 km area was the only variable that entered into the stepwise regression model.
The decrease in species evenness in the urban parks was due to the dominance of big brown bats (Eptesicus fuscus) in these parks. The percentage of big brown bats in our captures was positively related to percent Developed land in the
surrounding area. Our data suggest that urban parks may be important for conserving regional bat biodiversity. However, the
low species evenness in these parks suggests that some bat species may be susceptible to the effects of urbanization and may
be extirpated over time. Thus, management of urban as well as rural parks should strive to conserve as much bat roosting and
foraging habitat as possible. 相似文献
343.
Schoeneberger Marlies Logan T. K. Leukefeld Carl 《Population research and policy review》1999,18(1-2):119-136
The purpose of this study was to examine relationships between gender roles and HIV risk behavior, and perceptions and acceptance of the female condom among college students (n = 410). It was hypothesized that high hyperfeminine females and high hypermasculine males – those adhering to traditional gender roles – would engage in more HIV risk behaviors, including alcohol and drug use and various sexual practices, than those with lower hyperfemininity and hypermasculinity. It was also hypothesized that higher hyperfeminine females as well as higher hypermasculine males would perceive the female condom more negatively and would be less likely to view the female condom as a viable form of protection in the future. It was also hypothesized that high hyperfeminine females and high hypermasculine males would not accept the female condom as an alternative form of protection. Implications for prevention interventions are discussed. 相似文献
344.
T. Nagamitsu Kuniyasu Momose Tamiji Inoue David W. Roubik 《Researches on Population Ecology》1999,41(2):195-202
Floral resource partitioning among stingless bees (Trigona, Meliponini, Apidae) in a lowland rain forest in Sarawak, Malaysia, was investigated using tree towers and walkways in a
4-year study that included a general flowering period. We obtained 100 collections of insect visitors to flowers of varying
floral location and shape representing 81 plant species. The tendency of 11 species of stingless bees to visit specific flowers
with a particular floral location and shape was analyzed by logistic regression analysis. This analysis showed that the proportion
of flower visitor collections containing Trigona fuscobalteata and T. melanocephala differed according to floral location. The former was frequently collected at canopy and gap flowers, whereas the latter
was most often collected at understory flowers. The analysis also suggested that T. erythrogastra was more rarely collected at shallow flowers than at deep flowers. Analysis of the pollen diets of T. collina, T. fuscobalteata, T. melanocephala, and T. melina revealed that similarity of pollen sources differed among the six permutated pairs of the four species. The lowest mean rank
of similarity found was between T. fuscobalteata and T. melanocephala. This result supports the hypothesis that preference in visiting flowers in different locations leads to pollen resource
partitioning.
Received: May 14, 1997 / Accepted: April 23, 1999 相似文献
345.
Robinson A. Grover 《Theory and Decision》1974,4(3-4):277-299
This paper is an attempt to raise some general objections to the whole concept of making decisions on teleological principles. Its scope is finally the whole concept of how we rationally decide, on a teleological basis, to do any act at all. However the arguments developed here arise from the recent discussions about one particular species of teleological decision-making - utilitarianism. Therefore, while I hope that the paper has consequences that are important far beyond this one ethical theory, my objections are phrased in terms of direct arguments about utilitarianism. The recent lively debates on this topic make it easy to ask some interesting questions about this sort of goal-oriented theory. However, if my objections are correct, the scope of these questions is much wider than any one utilitarian theory (or cluster of theories) because my objections are about an assumption that is common to all teleological theories and not just to classical utilitarianism. 相似文献
346.
An integer linear programming model is presented for the scheduling of n products on m identical machines. The particular problem studied is one that occurs frequently in the fiberglass and textile industries. The model incorporates setup costs, lost production costs, and overtime costs. Due to the structure of the model, integer solutions can be obtained by explicitly restricting only a small number of the integer variables. This allows those responsible for scheduling to solve realistically sized problems in an efficient manner. Computational results are provided for a set of generated test problems. 相似文献
347.
348.
Dejian Lai Qiang Zhang Jose-Miguel Yamal Paula T. Einhorn Barry R. Davis 《统计学通讯:理论与方法》2017,46(18):8943-8951
Effective recruitment is a prerequisite for successful execution of a clinical trial. ALLHAT, a large hypertension treatment trial (N = 42,418), provided an opportunity to evaluate adaptive modeling of recruitment processes using conditional moving linear regression. Our statistical modeling of recruitment, comparing Brownian and fractional Brownian motion, indicates that fractional Brownian motion combined with moving linear regression is better than classic Brownian motion in terms of higher conditional probability of achieving a global recruitment goal in 4-week ahead projections. Further research is needed to evaluate how recruitment modeling can assist clinical trialists in planning and executing clinical trials. 相似文献
349.
The purpose of this study was to provide an initial investigation into the work–family conflict (WFC) experiences of individuals who hold a second job. Specifically, we proposed two opposing theoretical arguments regarding the relationship between WFC and four measures of well-being: life satisfaction, physical health, emotional exhaustion, and exercise for individuals who hold two jobs. In a sample of individuals working two jobs, we tested whether the effects of WFC arising from the first job and from the second job exerted an additive or interactive effect on employee well-being. Our results indicated that for emotional exhaustion, physical symptoms, and life satisfaction, the effects of WFC from two jobs are interactive; but that for exercise, the effects of WFC from two jobs are additive. In both cases, the additional WFC experienced as a result of working a second job contributed to the prediction of employee well-being over and above WFC from the first job. Results are discussed within the context of relevant theory, and suggestions are made for future research. 相似文献
350.
Nguyen T. P. Thao 《Asian Social Work and Policy Review》2016,10(2):225-236
Married Vietnamese immigrant women often face multiple stressors related to sociocultural adaptation and new family lives in South Korea. The purpose of this paper is to identify the different influences of acculturative and family life stress on depressive symptoms among Vietnamese immigrant wives. Data were collected through a questionnaire survey of 301 married Vietnamese immigrant women residing in South Korea. The study utilized linear regression analysis to test the relationships between the variables. The findings show that both acculturative and family life stress are positively related to depressive symptoms. Family life stress influences depressive symptoms to a greater extent than acculturative stress. The study emphasizes the significance of family‐related stress on mental health among married Vietnamese immigrant women in Korea and provides some implications for research, clinical practice, and policy. 相似文献