bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experiences and challenges of informal caregiving for Korean immigrants
Authors: Han Hae‐Ra , Choi Yun Jung , Kim Miyong T. , Lee Jong Eun , Kim Kim B. 
Published: August 2008

AbstractTitle.  Experiences and challenges of informal caregiving for Korean immigrants. Aim.  This paper is a report of a study designed to explore the caregiving experiences of Korean Americans.Background.  Increasing numbers of older people in the Asian population place important long‐term care demands on Asian caregivers, yet minimal attention has been given to the issue of caregiving in this group. The current study attempts to fill the gap by describing Korean American caregivers’ unique caregiving experiences from their perspectives.Method.  A qualitative research design using a focus group approach was employed to discuss caregiving experiences in a cultural context. Data were collected over an 8‐month period in 2005. Twenty‐four informants, mostly women, at varying points surrounding caregiving participated in a focus group interview. Each focus group lasted about 1 ½–2 hours. Thematic analysis was conducted by two bilingual researchers.Findings.  Three key themes were identified: the caregiver role – competing priorities and beliefs, the extent and impact of caregiving, and the need for education and culturally‐tailored support systems. Ten subthemes were identified within the three major themes: (1) facing double challenges; (2) changing attitudes about filial piety (Hyo); (3) providing care; (4) feeling out of control; (5) going through changing family dynamics; (6) being connected vs. providing connection; (7) paying back; (8) learning by themselves; (9) recognizing differences and (10) reconsidering geriatric care systems.Conclusion.  The caregiving experiences described by Korean American families point to the need to identify and develop more focused outreach programmes as well as more culturally appropriate support services for this rapidly increasing population.
Human and non‐human determinants of forest composition in southern Spain: evidence of shifts towards cork oak dominance as a result of management over the past century
Authors: Urbieta Itziar R. , Zavala Miguel A. , Marañón Teodoro 
Published: August 2008

AbstractAims  Both human and non‐human determinants have shaped Mediterranean forest structure over the last few millennia. The effects of recent human activities on forest composition, however, remain poorly understood. We quantified changes in forest composition during the past century in the mixed forests of Quercus suber (cork oak) and Q. canariensis (Algerian oak), and explored the effects of forest management and environmental (climate, topography) factors on forest structure at various spatial and temporal scales.Location  Mountains north of the Strait of Gibraltar (southern Spain).Methods  First, we quantified 20th‐century changes in species composition from a series of inventories in nine mixed forests (c. 40,000 ha), and examined them in terms of the management practices and environmental conditions. Second, we analysed present‐day Q. suber and Q. canariensis stand structure along environmental gradients at two spatial scales: (1) that of the forest landscape (c. 284 ha), combining local inventories and topographic variables and using a digital elevation model; and (2) regional (c. 87,600 km2), combining data from the Spanish Forest Inventory for the Andalusia region and estimates of climatic variables.Results  Historical data indicate anthropogenic changes in stand composition, revealing a sharp increase in the density of cork oaks over the last century. Forest management has favoured this species (for cork production) at the expense of Q. canariensis. The impact of management is imprinted on the present‐day forest structure. The abundance of both species increases with annual mean precipitation, and they coexist above 800 mm (the minimum threshold for Q. canariensis). Quercus suber dominates in most of the stands, and species segregation in the landscape is associated with the drainage network, Q. canariensis being clearly associated with moister habitats near streams.Main conclusions  Our study quantitatively exemplifies a recent human‐mediated shift in forest composition. As a result of forest management, the realized niche of the cork oak has been enlarged at the expense of that of Q. canariensis, providing further evidence for humans as major drivers of oak forest composition across the Mediterranean. Recent regeneration problems detected in Q. suber stands, a reduced demand for wood products, conservation policies, and climate change augur new large‐scale shifts in forest composition.
Is the spatial distribution of European beech (Fagus sylvaticaL.) limited by its potential height growth?
Authors: Seynave Ingrid , Gégout Jean‐Claude , Hervé Jean‐Christophe , Dhôte Jean‐François 
Published: August 2008

AbstractAim To improve our understanding of species range limits by studying how height growth, a trait related to plant survival, varies throughout the geographic range ofFagus sylvaticaL. in France.Location The geographic range of beech in France, representing the western area of its European distribution, within which this species exhibits range distribution limits in both plains and mountainous areas.Methods A generalized linear regression model was used to link beech growth performance to environmental variables using data from 819 plots of the French National Forest Inventory (IFN) database. This model was applied to predict potential growth on 97,281 IFN plots covering the geographic range of beech in France. A kriging technique was used to interpolate estimated growth potential. Finally, the performance of plot‐based predictions of potential growth from the map (i.e. map quality) was evaluated against an independent data set.Results The beech growth performance model highlighted the major impact of climate on potential tree growth at a broad spatial scale. The relevant climatic factors were related mainly to spring cold, summer heat, and winter temperatures and rainfall. The study also revealed the predictive power of soil parameters, which explained a large proportion of the variation in potential beech growth (c.30%). Analyses of height growth patterns near the boundary of the species range in France showed that the limit only partly coincides with the growth decline caused by climatic and soil factors. Along parts of the range limit, the predicted potential for growth was high, suggesting that in these areas the limit of the range could be explained by other factors, such as competition or constraints on reproduction.Main conclusions The spatial variation in the potential height growth ofFagus sylvaticacan be explained by environmental factors and is partly correlated with its regional range limits. By identifying areas where growth potential constrains the geographic range of species, environmental growth models can help to improve our knowledge of the spatial drivers of species geographic range limits and shed light on their response to future environmental changes.
Cytogeography of Solidago gigantea (Asteraceae) and its invasive ploidy level
Authors: Schlaepfer Daniel R. , Edwards Peter J. , Semple John C. , Billeter Regula 
Published: August 2008

AbstractAim  Newly formed polyploids experience problems of establishment and spread similar to those faced by newly introduced alien species. To understand the significance of polyploidy in biological invasions, we mapped the distribution of ploidy levels in Solidago gigantea Aiton in its native range in North America, and in Europe and East Asia where it is invasive.Location  North America, Europe and East Asia.Methods  Flow cytometry was used to measure ploidy levels in a total of 834 plants from 149 locations. Together with data from contributors and a literature review, ploidy‐level data were assembled for 336 locations. Cytogeographical maps from North America and Europe were prepared, incorporating new and previously published ploidy‐level data.Results  In the native range, diploid, tetraploid and hexaploid plants were found, and also one triploid and one pentaploid plant (2n = 3x and 2n = 5x, respectively, each being new reports for this species). There was a high degree of geographical separation among the ploidy levels, and populations with mixed ploidy were rare. However, four zones were identified where plants of different ploidy could come into contact. In Europe and East Asia, only tetraploid plants were found.Main conclusions  The geographical pattern in North America suggests that the ploidy levels are ecologically differentiated, although further investigations are needed to identify the nature of these differences. Alien populations appear to be exclusively tetraploid, but it is not clear whether this is because tetraploids were selectively introduced or because diploids were unsuccessful. In any case, comparisons between native and introduced populations need to account for ploidy level.
Phylogeographic structure and regional history of Lemniscomys striatus (Rodentia: Muridae) in tropical Africa
Authors: Nicolas Violaine , Mboumba Jean‐François , Verheyen Erik , Denys Christiane , Lecompte Emilie , Olayemi Ayodeji , Missoup Alain D. , Katuala Pionus , Colyn Marc 
Published: August 2008

AbstractAim  This study aims to elucidate the phylogeography of the murid rodent Lemniscomys striatus and to evaluate the relative roles of ecological change, habitat patchiness, rivers and geological barriers in structuring patterns of diversity.Location  Sub‐Saharan Africa.Methods  The extent of phylogeographic patterns and molecular genetic diversity (cytochrome b gene) were addressed in a survey of 128 individuals of L. striatus from 42 localities. Using maximum parsimony, maximum likelihood, Bayesian, network and genetic structure analyses, we inferred intraspecific relationships and tested hypotheses for historical patterns of gene flow within L. striatus.Results  Our results identified four major geographical clades within L. striatus: a West African clade, a Benin‐Nigeria clade, a Central African clade, and an East African clade. Several subclades were identified within these four major clades. Restricted gene flow with isolation by distance was recorded, which is congruent with the low dispersal ability of such a small murid rodent. No clear signal of population expansion was detected within clades or subclades.Main conclusions  The western rift system and the Volta and Niger rivers may have acted as long‐term extrinsic barriers to gene flow, resulting in the emergence of the four main clades of L. striatus. The observed pattern of mitochondrial variation observed within each clade probably results from late Pleistocene climatic and vegetation changes: during adverse conditions (forest expansion), L. striatus may have survived only in refugia, and then experienced range expansion under favourable conditions (savanna expansion).
Explanations for bird species range size: ecological correlates and phylogenetic effects in the Canary Islands
Authors: Carrascal Luis M. , Seoane Javier , Palomino David , Polo Vicente 
Published: August 2008

AbstractAim To explore the determinants of island occupancy of 48 terrestrial bird species in an oceanic archipelago, accounting for ecological components while controlling for phylogenetic effects.Location The seven main islands of the Canary archipelago.Methods We obtained field data on population density, habitat breadth and landscape distribution in Tenerife, Fuerteventura and La Palma, aiming to sample all available habitats and the gradient of altitudes. In total, 1715 line transects of 0.5 km were carried out during the breeding season. We also reviewed the literature for data on occupancy, the distance between the Canary Islands and the nearest distribution border on the mainland, body size and endemicity of the 48 terrestrial bird species studied. Phylogenetic eigenvector regression was used to quantify (and to control for) the amount of phylogenetic signal.Results The two measurements of occupancy (number of occupied islands or 10 × 10 km UTM squares) were tightly correlated and produced very similar results. The occupancy of the terrestrial birds of the Canary Islands during the breeding season had a very low phylogenetic effect. Species with broader habitat breadth, stronger preferences for urban environments, smaller body size, and a lower degree of endemicity had a broader geographical distribution in the archipelago, occupying a larger number of islands and 10 × 10 UTM squares.Main conclusions The habitat‐generalist species with a tolerance for novel urban environments tend to be present on more islands and to occupy a greater area, whereas large‐sized species that are genetically differentiated within the islands are less widespread. Therefore, some properties of the ranges of these species are explicable from basic biological features. A positive relationship of range size with local abundance, previously shown in continental studies, was not found, probably because it relies on free dispersal on continuous landmasses, which may not be applicable on oceanic islands.
Ecological niche modelling of montane mammals in the Great Basin, North America: examining past and present connectivity of species across basins and ranges
Authors: Waltari Eric , Guralnick Robert P. 
Published: August 2008

AbstractAim  The goal of this study was to determine the extent of suitable habitats across the basins and ranges of the Great Basin for 13 montane mammals in the present and during the Last Glacial Maximum (LGM). For all these mammal species, we test whether: (1) more suitable habitat was available in basin areas during the LGM; (2) suitable habitat shifted upwards in elevation between the LGM and the present; (3) more ranges have suitable habitat than are currently occupied; and (4) these species are currently restricted to suitable habitats at higher‐elevation range areas. We also examine whether and how much distributional response varies among these montane mammal species.Location  The Great Basin of western North America.Methods  We re‐examine the past and present distributions of 13 Great Basin montane mammals using ecological niche modelling techniques that utilize now widely available species occurrence data and new, fine‐scale past climatological GIS layers in the present and at the LGM. These methods provide an objective, repeatable means for visual comparison of past and present modelled distributions for species examined in previous biogeographical studies.Results  Our results indicate greater areal and lower elevational suitable habitat in the LGM than at present for nearly all montane mammals, and that there is more suitable habitat at present than is currently occupied. Our results also show that lowland areas provide suitable dispersal routes between ranges for most of the montane mammals both at the LGM and at present. However, three of the 13 species have little to no predicted suitable habitat in the LGM near currently occupied ranges, in contrast to the pattern for the other 10. For these species, the model results support more recent long‐distance colonization.Main conclusions  Our finding of suitable lowland dispersal routes in the present for most species supports and greatly extends similar findings from single‐species studies. Our results also provide a visually striking confirmation that changes in species distribution and colonization histories of Great Basin montane mammals vary in a fashion related to the tolerances and requirements of each of these species; this has previously been hypothesized but not rigorously tested for multiple montane mammals in the region.
Earlywood vessel size of oak as a potential proxy for spring precipitation in mesic sites
Authors: Fonti Patrick , García‐González Ignacio 
Published: August 2008

AbstractAim  In this study, we evaluate the importance of the mean earlywood vessel size of oaks as a potential proxy for climate in mesic areas.Location  The study was conducted in Switzerland at three forest sites dominated by oak (Quercus petraea and Q. pubescens). The three sites were in different climatic zones, varying mainly in terms of precipitation regime.Methods  Three 50‐year‐long site chronologies of mean earlywood vessel size and tree‐ring widths were obtained at each site and related to monthly meteorological records in order to identify the main variables controlling growth. The responses of mean vessel size to climate were compared with those of the width variables to evaluate the potential climatic information recorded by the earlywood vessels.Results  The results show that the mean vessel size has a different and stronger response to climate than ring‐width variables, although its common signal and year‐to‐year variability are lower. This response is better in particular at mesic sites, where it is linked to precipitation during spring, i.e. at the time of vessel formation, and is probably related to the occurrence of only a few processes controlling vessel growth, whereas radial increment is controlled by multiple and varying factors.Main conclusions  The mean earlywood vessel size of oak appears to be a promising proxy for future climate reconstructions of mesic sites, where radial growth is not controlled by a single limiting factor.
Spatial aspects of trait homogenization within the German flora
Authors: Winter Marten , Kühn Ingolf , Nentwig Wolfgang , Klotz Stefan 
Published: August 2008

AbstractAim  Biotic homogenization, the replacement of local biota by non‐indigenous and locally expanding species, is among the major effects of species invasions. Almost all studies related to this topic are focused on the species level, on taxonomic homogenization. Homogenization effects on trait diversity (functional homogenization) may be very important for ecosystem functioning, but they are rarely analysed, especially not at different spatial scales within a single study. This paper aims to examine how the presence of alien species (species introduced since 1500 ad) affects the distribution of ploidy levels in the German flora at different spatial scales.Location  Germany.Methods  We used a resampling method and the Morisita–Horn dissimilarity index to calculate dissimilarities of ploidy level within and between alien and indigenous plants at three different spatial scales in Germany: (1) the entire country as one location, (2) between grid cells, and (3) within grid cells of a lattice covering Germany.Results  We found a significant differentiation effect within grid cells of c. 130 km2, with alien plants increasing the variability of ploidy levels. The differentiation effect varies according to the scale used. At the coarsest scale (entire Germany), ploidy levels of alien plants tend to be more homogeneous in composition compared with those of native plants. At the intermediate scale (between grid cells), and even more pronounced at a small scale (within grid cells), ploidy levels are more heterogeneously distributed across Germany than those of native plant species.Main conclusions  Homogenization of ploidy levels at a large scale (entire Germany) and differentiation at a small scale (within grid cells) is comparable with the patterns found in taxonomic homogenization analyses. This analysis is a first step towards understanding the impacts of plant invasions on a trait level. Differentiation and homogenization of ploidy levels might mirror the distribution of related ecological traits and therefore might have an impact on ecosystem functioning.
Global gene expression mediated by Thermus thermophilus SdrP, a CRP/FNR family transcriptional regulator
Authors: Agari Yoshihiro , Kashihara Aiko , Yokoyama Shigeyuki , Kuramitsu Seiki , Shinkai Akeo 
Published: August 2008

Summary Thermus thermophilus SdrP is one of four cyclic AMP receptor protein (CRP)/fumarate and nitrate reduction regulator (FNR) family proteins from the extremely thermophilic bacterium T. thermophilus HB8. Expression of sdrP mRNA increased in the stationary phase during cultivation at 70°C. Although the sdrP gene was non‐essential, an sdrP‐deficient strain showed growth defects, particularly when grown in a synthetic medium, and increased sensitivity to disulphide stress. The expression of several genes was altered in the sdrP disruptant. Among them, we found eight SdrP‐dependent promoters using in vitro transcription assays. A predicted SdrP binding site similar to that recognized by Escherichia coli CRP was found upstream of each SdrP‐dependent promoter. In the wild‐type strain, expression of these eight genes tended to increase upon entry into the stationary phase. Transcriptional activation in vitro was independent of any added effector molecule. The hypothesis that apo‐SdrP is the active form of the protein was supported by the observation that the three‐dimensional structure of apo‐SdrP is similar to that of the DNA‐binding form of E. coli CRP. Based on the properties of the SdrP‐regulated genes found in this study, it is speculated that SdrP is involved in nutrient and energy supply, redox control, and polyadenylation of mRNA.
Developmentally regulated sphingolipid synthesis in African trypanosomes
Authors: Sutterwala Shaheen S. , Hsu Fong‐Fu , Sevova Elitza S. , Schwartz Kevin J. , Zhang Kai , Key Phillip , Turk John , Beverley Stephen M. , Bangs James D. 
Published: August 2008

SummarySphingolipids are essential components of eukaryotic membranes, and many unicellular eukaryotes, including kinetoplastid protozoa, are thought to synthesize exclusively inositol phosphorylceramide (IPC). Here we characterize sphingolipids from Trypanosoma brucei, and a trypanosome sphingolipid synthase gene family (TbSLS1–4) that is orthologous to Leishmania IPC synthase. Procyclic trypanosomes contain IPC, but also sphingomyelin, while surprisingly bloodstream‐stage parasites contain sphingomyelin and ethanolamine phosphorylceramide (EPC), but no detectable IPC. In vivo fluorescent ceramide labelling confirmed stage‐specific biosynthesis of both sphingomyelin and IPC. Expression of TbSLS4 in Leishmania resulted in production of sphingomyelin and EPC suggesting that the TbSLS gene family has bi‐functional synthase activity. RNAi silencing of TbSLS1–4 in bloodstream trypanosomes led to rapid growth arrest and eventual cell death. Ceramide levels were increased more than threefold by silencing suggesting a toxic downstream effect mediated by this potent intracellular messenger. Topology predictions support a revised six‐transmembrane domain model for the kinetoplastid sphingolipid synthases consistent with the proposed mammalian sphingomyelin synthase structure. This work reveals novel diversity and regulation in sphingolipid metabolism in this important group of human parasites.