bluuebunny/crossref_metadata_2025_split huggingface dataset:
Risk factors and characteristics associated with severe and difficult to treat asthma phenotype: an analysis of the ENFUMOSA group of patients based on the ECRHS questionnaire
Authors: Gaga M. , Papageorgiou N. , Yiourgioti G. , Karydi P. , Liapikou A. , Bitsakou H. , Zervas E. , Koulouris N. G. , Holgate S. T. ,   on behalf of the ENFUMOSA study group
Published: July 2005

SummaryBackground
Severe and difficult to treat asthma impairs health status and accounts for about half of asthma expenditure. In 1994, a European Network For Understanding Mechanisms of Severe Asthma (ENFUMOSA) was formed. A large group of patients from nine European countries has been selected.Objective
To examine the risk factors and symptoms associated with a phenotype of severe/difficult to treat asthma.Methods
The present report presents data assessed through the use of the European Community Respiratory Health Survey (ECRHS) Questionnaire in 148 mild–moderate controlled and 155 severe asthmatics from the ENFUMOSA group.Results
There is a negative association of severe asthma with reported allergy and with a family history of allergy (Odds ratio (OR)=0.45). Sharing a bedroom before the age of five is associated with a higher risk of severe asthma (OR=1.5) while childhood infections, play school attendance and exposure to allergens or animals are not. A larger proportion of severe asthma patients report symptoms at work (OR=2.7) or have to change jobs (OR=4.3) and fewer severe than mild patients are currently employed (OR=0.39). Smoking and exposure to smoke is similar in mild and severe asthma. Dietary habits do not differ between the groups, but severe asthmatics report eating less savoury snacks and there is a trend for lower intake of sweets.Conclusions
Analysis of the ECRHS questionnaire in the ENFUMOSA study shows that severe asthma patients experience more symptoms and their health status is impaired by their inability to work and perhaps eat freely. Personal and maternal history of allergy is associated with mild but not severe asthma. Other than sharing a bedroom before the age of 5 years, no childhood exposure risk factors associated with severe asthma could be identified from this analysis.
Arctic and North Atlantic Oscillation phase changes are recorded in the isotopes (δ18O and δ13C) of Cassiope tetragona plants
Authors: Welker Jeffrey M. , Rayback Shelly , Henry Greg H. R. 
Published: July 2005

AbstractThe Arctic and North Atlantic Oscillations (AO/NAO) are large‐scale annual modes of atmospheric circulation that have shifted in the last 30 years. Recent changes in arctic climate, including increasing surface air temperature, declining sea ice extent, and shifts in the amounts seasonality of precipitation are linked to the strong positive phase of the AO/NAO. Here, we show that phase changes in the AO/NAO are recorded in the isotopic (δ18O and Δ‐carbon isotope discrimination) characteristics of the long‐lived circum‐arctic plant, Cassiope tetragona, as summer rain has become a more important water source than snowmelt water which in turn has lead to decreases in Δ and reductions in plant stem growth. These isotopic records in C. tetragona may facilitate reconstructions of climate, plant–soil water relations, plant gas exchange attributes and a mechanistic understanding of growth responses to shifts in atmospheric circulation. If plant specimens were available for populations across the arctic as part of the International Polar Year, these archives could provide a circum‐arctic record of historical climate change and associated shifts in physiological plant performance and growth.
Synergy between small‐ and large‐scale feedbacks of vegetation on the water cycle
Authors: Scheffer Marten , Holmgren Milena , Brovkin Victor , Claussen Martin 
Published: July 2005

AbstractPredictions of the effects of climate change on the extent of forests, savannas and deserts are usually based on simple response models derived from actual vegetation distributions. In this review, we show two major problems with the implicitly assumed straightforward cause–effect relationship. Firstly, several studies suggest that vegetation itself may have considerable effects on regional climate implying a positive feedback, which can potentially lead to large‐scale hysteresis. Secondly, vegetation ecologists have found that effects of plants on microclimate and soils can cause a microscale positive feedback, implying that critical precipitation conditions for colonization of a site may differ from those for disappearance from that site. We argue that it is important to integrate these nonlinearities at disparate scales in models to produce more realistic predictions of potential effects of climate change and deforestation.
Phenolic compounds in seedlings ofBetula pubescensandB. pendulaare affected by enhanced UVB radiation and different nitrogen regimens during early ontogeny
Authors: Keski‐Saari Sarita , Pusenius Jyrki , Julkunen‐Tiitto Riitta 
Published: July 2005

AbstractWe studied the ability of tree seedlings to respond to two environmental factors, elevated ultraviolet B (UVB) radiation and availability of nitrogen (N), at the beginning of their development. Seeds of two birch species,Betula pubescensEhrh. (common white birch) andB. pendulaRoth (silver birch), were germinated and the seedlings grown in an experimental field in eastern Finland. The experimental design consisted of a constant 50% increase in UVB radiation (including a slight increase in UVA), a UVA control (a slight increase in UVA) and a control. The seedlings were fertilized with three levels of N. The experiment lasted for 2 months; aboveground biomass was measured and the most mature leaf of each seedling was taken for the analyses of phenolics. Growth of the seedlings was not significantly affected by enhanced UVB, but was increased by increasing N. Elevated UVB induced significant changes in phenolic compounds. Quercetin glycosides were accumulated in the leaves of both species in response to UVB; this is considered to be a protective response. However, the direction of the responses of individual phenolics to different N regimens differed. In addition, concentration of soluble condensed tannins was lower at moderate N than that at lower levels of N in both species; on the contrary, inB. pubescensthe concentration of insoluble condensed tannins was highest at moderate N. No significant interaction between UV and N was detected, and the responses of the two species were highly similar to UVB, while the responses to N regimens varied slightly more between species.
Historical land‐use legacy and Cortaderia selloana invasion in the Mediterranean region
Authors: Domènech Roser , Vilà Montserrat , Pino Joan , Gesti Josep 
Published: July 2005

AbstractTwo major components of global change: land‐use changes and intentional or accidental species introduction are threatening the conservation of native species worldwide. In particular, Mediterranean coastal areas are highly susceptible to the invasion of alien species and they also have experienced major changes in land use such as agricultural abandonment and urbanization. However, there has been little research done which quantitatively links biological invasions and the components of land‐use changes (i.e. number, trajectory and direction of the changes). We analysed the current distribution and abundance of Cortaderia selloana (Schultes et Schultes fil.) Asch. et Graebner, an alien ornamental species, in 332 fields in Aiguamolls de l'Empordà (Catalonia, NE Spain) and related the patterns of invasion to spatiotemporal data on land‐use changes from 1956 to 2003. Our aim was to determine which land uses had been more susceptible to C. selloana invasion during the last 5 years and to find out which components of land‐use changes triggered invasion. We found that 22.30% of the fields are currently invaded. In the last 5 years, fields have triplicated the total density of C. selloana. The presence of C. selloana decreases with the distance from urban areas. Invasion is over‐represented in pastures and old‐fields, and it has increased with time since abandonment. The presence of C. selloana was also associated to fields that had experienced many changes in land use in the last 46 years. The most heavily invaded fields were those that were pastures in 1956 and are now old fields in 2003. On average, the largest plants are found in agricultural field margins and in fields that had a disturbed land use both in 1956 and in 2003. Furthermore, pastures had the lowest proportion of reproductive plants. Overall, current C. selloana patterns of invasion can be explained by the historical legacy of land‐use changes.
Climate change‐driven forest fires marginalize the impact of ice cap wasting on Kilimanjaro
Authors: Hemp Andreas 
Published: July 2005

AbstractThe disappearing glaciers of Kilimanjaro are attracting broad interest. Less conspicuous but ecologically far more significant is the associated increase of frequency and intensity of fires on the slopes of Kilimanjaro, which leads to a downward shift of the upper forest line by several hundred meters as a result of a drier (warmer) climate since the last century. In contrast to common belief, global warming does not necessarily cause upward migration of plants and animals. Here, it is shown that on Kilimanjaro the opposite trend is under way, with consequences more harmful than those due to the loss of the showy ice cap of Africa's highest mountain.
Below‐ground responses of silver birch trees exposed to elevated CO2 and O3 levels during three growing seasons
Authors: Kasurinen Anne , Keinänen Minna M. , Kaipainen Saara , Nilsson Lars‐Ola , Vapaavuori Elina , Kontro Merja H. , Holopainen Toini 
Published: July 2005

AbstractField‐growing silver birch (Betula pendula Roth) clones (clone 4 and 80) were exposed to elevated CO2 and O3 in open‐top chambers for three consecutive growing seasons (1999–2001). At the beginning of the OTC experiment, all trees were 7 years old. We studied the single and interaction effects of CO2 and O3 on silver birch below‐ground carbon pools (i.e. effects on fine roots and mycorrhizas, soil microbial communities and sporocarp production) and also assessed whether there are any clonal differences in these below‐ground CO2 and O3 responses. The total mycorrhizal infection level of both clones was stimulated by elevated CO2 alone and elevated O3 alone, but not when elevated CO2 was used in fumigation in combination with elevated O3. In both clones, elevated CO2 affected negatively light brown/orange mycorrhizas, while its effect on other mycorrhizal morphotypes was negligible. Elevated O3, instead, clearly decreased the proportions of black and liver‐brown mycorrhizas and increased that of light brown/orange mycorrhizas. Elevated O3 had a tendency to decrease standing fine root mass and sporocarp production as well, both of these O3 effects mainly manifesting in clone 4 trees. CO2 and O3 treatment effects on soil microbial community composition (PLFA, 2‐ and 3‐OH‐FA profiles) were negligible, but quantitative PLFA data showed that in 2001 the PLFA fungi : bacteria‐ratio of clone 80 trees was marginally increased because of elevated CO2 treatments. This study shows that O3 effects were most clearly visible at the mycorrhizal root level and that some clonal differences in CO2 and O3 responses were observable in the below‐ground carbon pools. In conclusion, the present data suggests that CO2 effects were minor, whereas increasing tropospheric O3 levels can be an important stress factor in northern birch forests, as they might alter mycorrhizal morphotype assemblages, mycorrhizal infection rates and sporocarp production.
The microfood web of grassland soils responds to a moderate increase in atmospheric CO2
Authors: Sonnemann Ilja , Wolters Volkmar 
Published: July 2005

AbstractThe response of the soil microfood web (microflora, nematodes) to a moderate increase in atmospheric CO2(+20%) was investigated by means of a free air CO2enrichment experiment. The study was carried out in a seminatural temperate grassland for a period of 4 consecutive years (1 year before fumigation commenced and 3 years with fumigation). Several soil biological parameters showed no change (microbial biomass, bacterial biomass) or decline (microbial respiration) in the first year of elevated CO2treatment as compared with controls. Each of these parameters were higher than controls, however, after 3 years of treatment. The relative abundance of predaceous nematodes also decreased in year 1 of the experiment, increased in year 2, but decreased again in year 3. In contrast, the relative abundance of root hair feeding nematodes, at first, increased under elevated CO2and then returned to the initial level again. Increased microbial biomass indicates enhanced C storage in the labile carbon pool of the active microfood web in subsequent years. According to measurements on the amounts of soil extractable C, changes in resource availability seem to be key to the response of the soil microfood web.We found a strong response of bacteria to elevated CO2, while the fungal biomass remained largely unchanged. This contrasts to findings reported in the literature. We hypothesize that this may be because of contrasting effects of different levels of CO2enrichment on the microbial community (i.e. stimulation of bacteria at moderate levels and stimulation of fungi at high levels of CO2enrichment). However, various CO2effects observed in our study are similar in magnitude to those observed in other studies for a much higher level of atmospheric carbon. These include the particular sensitivity of predaceous nematodes and the long‐term increase of microbial respiration. Our findings confirm that the potential of terrestrial ecosystems to accumulate additional carbon might be lower than previously thought. Furthermore, CO2‐induced changes of temperate grassland ecosystems might emerge much earlier than expected.
Spatial and temporal variation of phenological growing season and climate change impacts in temperate eastern China
Authors: Chen Xiaoqiu , Hu Bing , Yu Rong 
Published: July 2005

AbstractUsing phenological and normalized difference vegetation index (NDVI) data from 1982 to 1993 at seven sample stations in temperate eastern China, we calculated the cumulative frequency of leaf unfolding and leaf coloration dates for deciduous species every 5 days throughout the study period. Then, we determined the growing season beginning and end dates by computing times when 50% of the species had undergone leaf unfolding and leaf coloration for each station year. Next, we used these beginning and end dates of the growing season as time markers to determine corresponding threshold NDVI values on NDVI curves for the pixels overlaying phenological stations. Based on a cluster analysis, we determined extrapolation areas for each phenological station in every year, and then implemented the spatial extrapolation of growing season parameters from the seven sample stations to all possible meteorological stations in the study area.Results show that spatial patterns of growing season beginning and end dates correlate significantly with spatial patterns of mean air temperatures in spring and autumn, respectively. Contrasting with results from similar studies in Europe and North America, our study suggests that there is a significant delay in leaf coloration dates, along with a less pronounced advance of leaf unfolding dates in different latitudinal zones and the whole area from 1982 to 1993. The growing season has been extended by 1.4–3.6 days per year in the northern zones and by 1.4 days per year across the entire study area on average. The apparent delay in growing season end dates is associated with regional cooling from late spring to summer, while the insignificant advancement in beginning dates corresponds to inconsistent temperature trend changes from late winter to spring. On an interannual basis, growing season beginning and end dates correlate negatively with mean air temperatures from February to April and from May to June, respectively.
Land‐use change and water losses: the case of grassland afforestation across a soil textural gradient in central Argentina
Authors: Nosetto Marcelo D. , Jobbágy Esteban G. , Paruelo José M. 
Published: July 2005

AbstractVegetation changes, particularly those involving transitions between tree‐ and grass‐dominated covers, often modify evaporative water losses as a result of plant‐mediated shifts in moisture access and demand. Massive afforestation of native grasslands, particularly important in the Southern Hemisphere, may have strong yet poorly quantified effects on the hydrological cycle. We explored water use patterns inEucalyptus grandisplantations and the native humid grasslands that they replace in Central Argentina. In order to uncover the interactive effects that land cover type, soil texture and climate variability may have on evaporative water losses and water use efficiency, we estimated daily evapotranspiration (ET) in 117 tree plantations and grasslands plots across a soil textural gradient (clay‐textured Vertisols to sandy‐textured Entisols) using radiometric information from seven Landsat scenes, existing timber productions records, and13C measurements in tree stems. Tree plantations had cooler surface temperatures (−5°C on average) and evaporated more water (+80% on average) than grasslands at all times and across all sites. Absolute ET differences between grasslands and plantations ranged from ∼0.6 to 2 mm day−1and annual up‐scaling suggested values of ∼630 and ∼1150 mm yr−1for each vegetation type, respectively. The temporal variability of ET was significantly lower in plantations compared with grasslands (coefficient of variation 36% vs. 49%). Daily ET increased as the water balance became more positive (accumulated balance for previous 18 days) with a saturation response in grassland vs. a continuous linear increase in plantations, suggesting lower ecophysiological limits to water loss in tree canopies compared with the native vegetation. Plantation ET was more strongly affected by soil texture than grassland ET and peaked in coarse textured sites followed by medium and fine textured sites. Timber productivity as well as13C concentration in stems peaked in medium textured sites, indicating lower water use efficiency on extreme textures and suggesting that water limitation was not responsible for productivity declines towards finer and coarser soils. Our study highlighted the key role that vegetation type plays on evapotranspiration and, therefore, in the hydrological cycle. Considering that tree plantations may continue their expansion over grasslands, problematic changes in water management and, perhaps, in local climate can develop from the higher evaporative water losses of tree plantations.
Statistical analysis of the major variables controlling methane emission from rice fields
Authors: Yan Xiaoyuan , Yagi Kazuyuki , Akiyama Hiroko , Akimoto Hajime 
Published: July 2005

AbstractRice cultivation is an important anthropogenic source of atmospheric methane (CH4), the emission of which is affected by management practices. Many field measurements have been conducted in major rice‐producing countries in Asia. We compiled a database of CH4 emissions from rice fields in Asia from peer‐reviewed journals. We developed a statistical model to relate CH4 flux in the rice‐growing season to soil properties, water regime in the rice‐growing season, water status in the previous season, organic amendment and climate. The statistical results showed that all these variables significantly affected CH4 flux, and explained 68% of the variability. Organic amendment and water regime in the rice‐growing season were the top two controlling variables; climate was the least critical variable. The average CH4 fluxes from rice fields with single and multiple drainages were 60% and 52% of that from continuously flooded rice fields. The flux from fields that were flooded in the previous season was 2.8 times that from fields previously drained for a long season and 1.9 times that from fields previously drained for a short season. In contrast to the previously reported optimum soil pH of around neutrality, soils with pH of 5.0–5.5 gave the maximum CH4 emission. The model results demonstrate that application of rice straw at 6 t ha−1 before rice transplanting can increase CH4 emission by 2.1 times; when applied in the previous season, however, it increases CH4 emission by only 0.8 times. Default emission factors and scaling factors for different water regimes and organic amendments derived from this work can be used to develop national or regional emission inventories.
Relationship of Student Undergraduate Achievement and Personality Characteristics in a Total Web‐Based Environment: An Empirical Study
Authors: Schniederjans Marc J. , Kim Eyong B. 
Published: July 2005

ABSTRACTWeb‐based education is a popular format for the delivery of college courses. Research has shown that it may not be the best form of education for all students. Today, many students (and student advisors) face a choice in course delivery format (i.e., Web‐based or more traditional classroom courses). This research study examines the relationship between student personality characteristics and their achievement scores as a means of identifying predictors of academic success in an undergraduate business program using Web‐based education. The results of the study show that four basic personality characteristics are highly correlated to student achievement in Web‐based courses. Use of these personality characteristics as variables in a regression model is shown to be a highly accurate predictive tool to aid students in the decision as to whether to take a particular Web‐based course format or a more traditional classroom course.
Teaching with the Case Method Online: Pure Versus Hybrid Approaches
Authors: Webb Harold W. , Gill Grandon , Poe Gary 
Published: July 2005

ABSTRACTThe impact of hybrid classroom/distance education approaches is examined in the context of the case method. Four distinct semester‐long treatments, which varied mixes of classroom and online discussion, were used to teach a graduate MIS survey course. Specific findings suggest that by using Web technology, college instructors may offer students the option of participating in high‐quality courses using the case method pedagogy in an online environment. Students not only appear to do as well as in the traditional classroom, but the data suggest that students in the online environment may perform better at multiple levels of learning outcomes, especially when using a blend of classroom and online technologies. Furthermore, the precepts of the case method pedagogy may be enhanced by the use of online discussions. Instructors employing the technique may find their own importance devalued, while the time demands of the approach can be much greater than for traditional classes. The findings infer that it is the model of learning and its fit with supporting technologies, rather than the presence of technology per se, which enhances learning outcomes.