University of Hawaii at Manoa

About: University of Hawaii at Manoa is a education organization based out in Honolulu, Hawaii, United States. It is known for research contribution in the topics: Population & Sea surface temperature. The organization has 13693 authors who have published 25161 publications receiving 1023924 citations.

A global comparison of plant invasions on oceanic islands

Abstract: Oceanic islands have long been considered to be particularly vulnerable to biotic invasions, and much research has focused on invasive plants on oceanic islands. However, findings from individual islands have rarely been compared between islands within or between biogeographic regions. We present in this study the most comprehensive, standardized dataset to date on the global distribution of invasive plant species in natural areas of oceanic islands. We compiled lists of moderate (5–25% cover) and dominant (>25% cover) invasive plant species for 30 island groups from four oceanic regions (Atlantic, Caribbean, Pacific, and Western Indian Ocean). To assess consistency of plant behaviour across island groups, we also recorded present but not invasive species in each island group. We tested the importance of different factors discussed in the literature in predicting the number of invasive plant species per island group, including island area and isolation, habitat diversity, native species diversity, and human development. Further we investigated whether particular invasive species are consistently and predictably invasive across island archipelagos or whether island-specific factors are more important than species traits in explaining the invasion success of particular species. We found in total 383 non-native spermatophyte plants that were invasive in natural areas on at least one of the 30 studied island groups, with between 3 and 74 invaders per island group. Of these invaders about 50% (181 species) were dominants or co-dominants of a habitat in at least one island group. An extrapolation from species accumulation curves across the 30 island groups indicates that the total current flora of invasive plants on oceanic islands at latitudes between c. 35°N and 35°S may eventually consist of 500–800 spermatophyte species, with 250–350 of these being dominant invaders in at least one island group. The number of invaders per island group was well predicted by a combination of human development (measured by the gross domestic product (GDP) per capita), habitat diversity (number of habitat types), island age, and oceanic region (87% of variation explained). Island area, latitude, isolation from continents, number of present, non-native species with a known invasion history, and native species richness were not retained as significant factors in the multivariate models. Among 259 invaders present in at least five island groups, only 9 species were dominant invaders in at least 50% of island groups where they were present. Most species were invasive only in one to a few island groups although they were typically present in many more island groups. Consequently, similarity between island groups was low for invader floras but considerably higher for introduced (but not necessarily invasive) species – especially in pairs of island groups that are spatially close or similar in latitude. Hence, for invasive plants of natural areas, biotic homogenization among oceanic islands may be driven by the recurrent deliberate human introduction of the same species to different islands, while post-introduction processes during establishment and spread in natural areas tend to reduce similarity in invader composition between oceanic islands. We discuss a number of possible mechanisms, including time lags, propagule pressure, local biotic and abiotic factors, invader community assembly history, and genotypic differences that may explain the inconsistent performance of particular invasive species in different island groups.

A change in the cluster environments of radio galaxies with cosmic epoch

Abstract: The results of an investigation into the cluster environments of radio galaxies spanning a wide range of radio power within a narrow range of redshift at z about 0.5 are presented. It is found that about half of the powerful classical double radio sources at z about 0.5 inhabit rich clusters, even though similar sources avoid such environments at low redshift. It is shown that this change includes not only the most powerful sources, but also sources of moderate power where a direct comparison with low-redshift sources is possible. The lowest power radio galaxies appear to inhabit similar environments at both epochs. In deriving these results, it is shown that the absolute magnitudes of the radio galaxies, and probably also of characteristic L(asterisk) galaxies, have not changed significantly since z about 0.5. The implications for the cosmological evolution of the radio source population are discussed. 77 refs.

Combined Postmenopausal Hormone Therapy and Cardiovascular Disease: Toward Resolving the Discrepancy between Observational Studies and the Women's Health Initiative Clinical Trial

Abstract: Observational research on postmenopausal hormone therapy suggests a 40-50% reduction in coronary heart disease incidence among women using these preparations. In contrast, the Women's Health Initiative clinical trial of estrogen plus progestin found an elevated incidence over a 5.6-year intervention period through July 7, 2002. Toward explaining this discrepancy, the authors analyzed data from this trial, which included 16,608 postmenopausal women aged 50-79 years, and corresponding data from 53,054 women in the Women's Health Initiative observational study, 33% of whom were estrogen-plus-progestin users at baseline. Estrogen-plus-progestin hazard ratio estimates for coronary heart disease, stroke, and venous thromboembolism in the observational study were 39-48% lower than those in the clinical trial following age adjustment. However, hazard ratios tended to decrease with increasing time from initiation of estrogen-plus-progestin use, and observational study hazard ratio estimates are heavily weighted by longer-term use while clinical trial hazard ratio estimates reflect shorter-term use. Following control for time from estrogen-plus-progestin initiation and confounding, hazard ratio estimates were rather similar for the two cohorts, although there was evidence of some remaining difference for stroke. These analyses have implications for both the design and the analysis of observational studies.

Arthropod succession patterns in exposed carrion on the island of O'ahu, Hawaiian Islands, USA.

Abstract: Arthropod succession patterns in exposed carrion were observed at 2 sites on the island of O‘ahu, Hawaiian Islands, USA. Five stages of decomposition were recognized: fresh, bloated, decay, dry, and remains. Differences in species composition at each of the 2 sites (Diamond Head Crater and Mānoa Valley) and in microhabitats resulted in differences in the duration of stages of decomposition between sites.

Defining Successful Aging: A Tangible or Elusive Concept?

Abstract: Purpose of the Study: Everyone w ants to age successfully; however, the definition and criteria of successful aging remain vague for laypersons, researchers, and policymakers in spite of decades of research on the topic. This paper highlights work of scholars who made significant theoretical contributions to the topic. Design and Methods: A thorough review and evaluation of the literature on successful aging was undertaken. Results: Our review includes early gerontological definitions of successful aging and related concepts. Historical perspectives reach back to philosophical and religious texts, and more recent approaches have focused on both process- and outcomeoriented models of successful aging. We elaborate on Baltes and Baltes’ theory of selective optimization with compensation [Baltes, P. B., & Baltes, M. M. (1990a). Psychological perspectives on successful aging: The model of selective optimization with compensation. In P. B. Baltes & M. M. Baltes (Eds.), Successful aging: Perspectives from the behavioral sciences (pp. 1–34). United Kingdom: Cambridge University Press], Kahana and Kahana’s preventive and corrective proactivity model [Kahana, E., & Kahana, B. (1996). Conceptual and empirical advances in understanding aging well through proactive adaptation. In V. Bengtson (Ed.), Adulthood and aging: Research on continuities and discontinuities (pp. 18–40). New York: Springer], and Rowe and Kahn’s model of successful aging [Rowe, J. W., & Kahn, R. L. (1998). Successful aging. New York: Pantheon Books], outlining their commonalities and differences. Additional views on successful aging emphasize subjective versus objective perceptions of successful aging and relate successful aging to studies on healthy and exceptional longevity.