bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxygen and methane depletion in soil affected by leakage of natural gas
Authors: Steven M. D. , Smith K. L. , Beardsley M. D. , Colls J. J. 
Published: November 2006

SummaryAs part of a study to simulate plant responses to leaks from pipelines, we injected natural gas into soil at a depth of 1 m in plots of grass, wheat and beans. Measurements of oxygen and methane in soil exposed to gas show that oxygen is depleted significantly to values less than would be caused by simple displacement by natural gas, indicating consumption within the soil by methanotrophic bacteria. Gas concentrations were clustered into two groups: 18% of the oxygen values were less than 1% by volume and 52% of the methane values were less than 5% by volume, indicating a tendency towards either oxygen‐limiting or methane‐limiting conditions. Oxygen depletion was significantly greater in summer. Depletion rates were greatest under grass, and least under wheat. In grass, 36% of the variation in depletion is explained by soil temperature at 10 cm with Q10 = 2.0 over the 0–20°C range. We developed a model that accounts for three gas exchange mechanisms: soil‐air displacement by the injected gas; gas consumption by bacteria; and re‐infusion of the soil atmosphere to account for a net loss of gas volume by consumption. Using this model, we calculate that an average of 37% of the methane was consumed. At initial methane concentrations less than 10% by volume, as much as 100% of the gas was consumed, but consumption efficiency decreased rapidly thereafter. These findings indicate that the soil sink for methane is dynamic and adaptive, acting as a significant constraint on underground methane sources, limited primarily by oxygen availability.
Yield response of crops amended with sewage sludge in the field is more affected by sludge properties than by final soil metal concentration
Authors: De Brouwere K. , Smolders E. 
Published: November 2006

SummaryAdverse effects on crop yield or quality have been reported in sewage‐sludge treated soils at soil total metal concentrations below those of the current EU directives. A field trial was set up in Belgium (2002–2004) to assess crop response to the application of sewage sludge below these soil thresholds but with sludge metal concentrations either above (high‐metal) or below (low‐metal) sludge metal limits. Two lime‐stabilized and two raw, dewatered sludges were applied annually at rates of 10, 25 and 50 t dry matter (dm) ha−1 for 3 years with four rates of N‐fertilizer as a reference. Final soil metal concentrations increased to maximums of 1.6 mg Cd kg−1 and 225 mg Zn kg−1 through sludge applications. Maize yield was marginally affected by treatments in year 1, whereas wheat and barley grain yields in subsequent years increased up to threefold with increasing sludge or fertilizer rates and were mainly explained by grain‐N. However, the grain yield of winter wheat in year 2 was reduced by about 14% in lime‐stabilized high‐metal sludge treatments compared with wheat receiving N‐fertilizer at equivalent grain‐N. Wheat grain and straw analysis showed no nutrient deficiencies but Zn concentrations in grain and straw were greater than in N‐fertilizer and lime‐stabilized, low‐metal sludge treatments, suggesting Zn toxicity. Sludge properties other than Cd concentration (e.g. electrical conductivity) affected crop Cd in the first year (maize), whereas significant correlations between Cd application and wheat grain Cd were found in the second year. Wheat grain Cd concentrations reached the international trade guideline of 0.1 mg Cd kg−1 fresh weight in the plots amended with lime‐treated, high‐metal sludge even though soil Cd remained below EU limits. In the third year, barley grain Cd remained largely below EU limits. We discuss the possibility that sludge properties rather than soil total metal concentrations are related to effects on crops in the initial years after sludge applications. In none of the 3 years were any adverse effects on crops found for sludge meeting current EU regulations.
Suppression of major histocompatibility complex class II‐associated invariant chain enhances the potency of an HIV gp120 DNA vaccine
Authors: Lu Xueqing , Wu Shuzhen , Blackwell Catherine E. , Humphreys Robert E. , Von Hofe Eric , Xu Minzhen 
Published: November 2006

SummaryOne function of the major histocompatibility complex (MHC) class II‐associated invariant chain (Ii) is to prevent MHC class II molecules from binding endogenously generated antigenic epitopes. Ii inhibition leads to MHC class II presentation of endogenous antigens by APC without interrupting MHC class I presentation. We present data that in vivo immunization of BALB/c mice with HIV gp120 cDNA plus an Ii suppressive construct significantly enhances the activation of both gp120‐specific T helper (Th) cells and cytotoxic T lymphocytes (CTL). Our results support the concept that MHC class II‐positive/Ii‐negative (class II+/Ii–) antigen‐presenting cells (APC) present endogenously synthesized vaccine antigens simultaneously by MHC class II and class I molecules, activating both CD4+ and CD8+ T cells. Activated CD4+ T cells locally strengthen the response of CD8+ CTL, thus enhancing the potency of a DNA vaccine.
Differential type I interferon activation and susceptibility of dendritic cell populations to porcine arterivirus
Authors: Loving Crystal L. , Brockmeier Susan L. , Sacco Randy E. 
Published: November 2006

SummaryDendritic cells (DCs) play a role in anti‐viral immunity by providing early innate protection against viral replication and by presenting antigen to T cells for initiation of the adaptive immune response. Studies show the adaptive response to porcine reproductive and respiratory syndrome virus (PRRSV) is ineffective for complete viral elimination. Other studies describe the kinetics of the adaptive response to PRRSV, but have not investigated the early response by DCs. We hypothesize that there is an aberrant activation of DCs early in PRRSV infection; consequently, the adaptive response is triggered inadequately. The current study characterized a subtype of porcine lung DCs (L‐DCs) and investigated the ability of PRRSV to infect and replicate in L‐DCs and monocyte‐derived DCs (MDDCs). Furthermore, the type I interferon anti‐viral response to PRRSV with and without the addition of recombinant porcine IFN‐α (rpIFN‐α), an important cytokine that signals for anti‐viral mediator activation, was analysed. Results show that PRRSV replicated in MDDCs but not L‐DCs, providing evidence that these cells have followed distinct differentiation pathways. Although both cell types responded to PRRSV with an induction of IFN‐β mRNA, the magnitude and duration of the response differed between cell types. The addition of rpIFN‐α was protective in MDDCs, and mRNA synthesis of Mx (myxovirus resistant) and PKR (double‐stranded RNA dependent protein kinase) was observed in both cell types after rpIFN‐α addition. Overall, PRRSV replicated in MDDCs but not L‐DCs, and rpIFN‐α was required for the transcription of protective anti‐viral mediators. DC response to PRRSV was limited to IFN‐β transcription, which may be inadequate in triggering the adaptive immune response.
MEKK3 is essential for lipopolysaccharide‐induced interleukin‐6 and granulocyte–macrophage colony‐stimulating factor production in macrophages
Authors: Kim Kihwan , Duramad Omar , Qin Xiao‐Feng , Su Bing 
Published: November 2006

SummaryMitogen‐activated protein/ERK kinase kinase 3 (MEKK3) is a Ser/Thr protein kinase belonging to the MEKK/STE11 subgroup of the MAP3K family. Recently, we found that MEKK3 plays a critical role in interleukin‐1 (IL‐1) receptor and Toll‐like receptor 4 signalling using established primary mouse embryonic fibroblast (MEF) cell lines. However, the function of MEKK3 in immune cells has not been studied because germ‐line MEKK3 knockout mice are embryonically lethal between embryonic days 10 and 11. In this study, we used small interference RNA to the mouse Mekk3 gene to specifically knock down MEKK3 expression in the macrophage line Raw264.7. We found that the lipopolysaccharide‐induced IL‐6 and granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) production was dramatically decreased in MEKK3 knockdown cells whereas the tumour necrosis factor‐α and IL‐1β production were not affected. We also observed that the ERK1/2, p38 and JNK MAPK induction in MEKK3 knockdown cells were moderately inhibited within the first 60 min of stimulation, while the ERK and p38 were more severely inhibited after 2–4 hr of stimulation. Degradation of IκBα was also partially blocked in MEKK3 knockdown cells. Notably, the impairment in IL‐6 and GM‐CSF production in the MEKK3 knockdown cells was restored by reintroducing a human Mekk3 cDNA that could not be targeted by mouse Mekk3‐siRNAs. In conclusion, this study showed that MEKK3 is a crucial and specific regulator of the proinflammatory cytokines IL‐6 and GM‐CSF in macrophages and provided a novel method for investigating MEKK3 function in other immune cells.
Does supplementary prenatal nursing and home visitation reduce healthcare costs in the year after childbirth?
Authors: Au Flora , Shiell Alan , Van Der Pol Marjon , Johnston David W. , Tough Suzanne 
Published: November 2006

Aim. This paper reports the costs of a programme of supplementary prenatal care, including healthcare costs, in the year following childbirth.Background. Publicly funded healthcare systems have provided pregnant women with adequate medical care, but access to resources to address their non‐medical needs is still an issue. To improve women's access to pregnancy‐related resources, a community‐based, prenatal programme involving consultations with a specialist nurse, or nurse plus a home visitor was evaluated.Method. A sample of 284 women who had participated in a randomized controlled trial of the prenatal care programme participated in this partial economic analysis. Women had been randomized to one of three trial arms: (1) standard care, (2) standard care plus consultations with a specialist prenatal care nurse, or (3) standard care plus nurse consultations and a home visitor. For the economic study, each woman was asked about her and her baby's use of healthcare services in the 12 months after the baby's birth. Health service utilization was multiplied by the unit cost of each service and summed to arrive at the total cost of services used. The study was undertaken in 2004.Results. Supplementary prenatal care neither increased the use of health services nor resulted in savings in health spending. Compared with standard care, women in the two intervention groups made more use of family physicians and less use of paediatricians, but no significant differences in the overall costs of health care were noted.Conclusion. While supplementary prenatal care had no impact on costs, some benefits occurred for those at greatest risk of not accessing services. However, it would be premature to draw widespread recommendations for policy from the results of a single study. Further investment in prenatal care should continue to be accompanied by rigorous evaluation of its costs and the value that women place on the service provided.
Disentangling the effects of psychological and physical work demands on sleep, recovery and maladaptive chronic stress outcomes within a large sample of Australian nurses
Authors: Winwood Peter C. , Lushington Kurt 
Published: November 2006

Aim.  This paper reports a study to determine if different types of work strain experienced by nurses, particularly those of an essentially psychological nature, such as emotional demand, mental effort and problems with peers and/or supervisors, have a differential impact on sleep quality and overall recovery from work strain, compared with physical work strains, and lead to higher maladaptive chronic fatigue outcomes.Background.  Various studies have shown that the dominant work‐demand strain associated with nursing work can vary between different areas of nursing. For example, whereas emotional strain is reported to be the principal strain associated with work in areas such as oncology, haematology and renal units, medical and surgical unit nurses report work pace and staffing issues as the dominant work strain. Purely physical strain seems to be less commonly reported as a concern.Method.  A large sample (n = 760) of Australian nurses working in a large metropolitan hospital completed questionnaires on their work demands, sleep quality, fatigue, and recovery between shifts in January 2004.Findings.  A high work pace exacerbates the psychological rather than the physical strain demands of nursing. Psychological strain affects sleep quality and impairs recovery from overall work strain between shifts. This combination is highly predictive of serious maladaptive stress/fatigue outcomes among nurses.Conclusion.  Coping with psychological stressors adequately is an important requirement for nurses in order to avoid adverse health effects and maintain a long‐term career in nursing. Appropriate training of undergraduate nursing students in managing the stresses they are likely to encounter would seem to be an essential requirement for the 21st century. Such training might constitute an important long‐term component in overcoming the chronic nurse shortages evident in many countries.
Organizational predicaments: ethical conditions for nursing research
Authors: Toffoli Luisa , Rudge Trudy 
Published: November 2006

Aim.  This paper highlights the sometimes problematic matter of access to the field in clinical ethnographic research by discussing a hypothetical scenario of an instance of change in the terms of access.Background.  A review of the methodological literature about research access revealed that there was little in the nursing literature about this issue, although anecdotally many nurse researchers reveal that access is not unproblematic and requires active maintenance to ensure smooth operation of a project. However, in returning to literature in sociology and anthropology, where gaining access for fieldwork is not considered so routine, we found much in the literature about dilemmas, predicaments and conflicts over access, confidentiality and anonymity that were not mentioned in nursing research about access to clinical areas. We returned also to the ethical and legal framework guiding access practices so as to explore the issues in fieldwork situations.Discussion.  In exploring the problems arising from maintaining confidentiality, safety of participants and researchers, it is clear that the much‐vaunted insider status is both a boon and a burden. Intimate and inquisitive research using ethnographic techniques has the potential to unsettle organizations and workers through the very processes used to undertake the research.Conclusion.  Ethical comportment is not enough to protect a study. A more overt and less naïve approach to access for fieldwork is required to better inform future nurse researchers how to maintain access to the field and the requirement of constant negotiation and adjustment.
Impact of recurrent changes in the work environment on nurses’ psychological well‐being and sickness absence
Authors: Verhaeghe Rik , Vlerick Peter , Gemmel Paul , Maele Georges Van , Backer Guy De 
Published: November 2006

Aim.  This paper is a report of a study of how the occurrence and appraisal of recurrent changes in the work environment of hospital nurses affect psychological well‐being (i.e. job satisfaction, eustress and distress) and absence through illness.Background.  Many researchers have demonstrated the impact of major organizational changes on employees’ psychological well‐being, but only a few have focused on the permanent consequences in work conditions. In a contemporary healthcare setting, an increased number of recurrent operational changes has become a normal characteristic of nurses’ work environment. Specific work situations have frequently been associated with occupational stress, whereas employees’ appraisal of recurrent changes as stressors and their relation to psychological well‐being and health outcomes (i.e. sickness absence) have been dismissed.Methods.  A cross‐sectional questionnaire survey was conducted in 2003 with 2094 Registered Nurses in 10 general hospitals. Logistic regressions were used to investigate the impact on psychological well‐being and prospectively measured rates of sickness absence (frequency and duration).Results.  The occurrence of changes in the work environment (in the past 6 months) had had a negative impact on staff psychological well‐being. Nurses who had been confronted with changes scored statistically significantly higher for distress. Changes appraised as threatening were negatively related to job satisfaction and eustress, and positively related to distress and sickness absence (frequency and duration). Changes appraised as challenging were positively related to job satisfaction and eustress but had no impact on distress and sickness absence.Conclusion.  Future research should take into consideration the impact of the occurrence and appraisal of recurrent changes in the work environment of healthcare employees (i.e. Registered Nurses) on psychological well‐being and sickness absence. This should also be considered by managers when dealing with these nursing workforce issues.
Women's perceptions of partner support and conflict in the development of postpartum depressive symptoms
Authors: Dennis Cindy‐Lee , Ross Lori 
Published: November 2006

Aim.  This paper reports a study examining the influence of maternal perceptions of conflict and relationship‐ and postpartum‐specific support from the partner on the development of depressive symptoms in the first 8‐weeks postpartum.Background.  Although the quality of a woman's relationship with her partner has been associated with risk for postpartum depression, few studies have examined which elements of partner‐specific support and conflict are determinants of maternal mental health.Methods.  Self‐administered measures of partner support (Social Provisions Checklist, Postpartum Partner Support Scale), partner conflict (Quality of Relationships Inventory), and depression (Edinburgh Postnatal Depression Scale) were mailed postnatally to a population‐based sample of 396 mothers between April 2001 to January 2002. Differences in partner support and conflict at 1 and 4‐weeks postpartum were examined between those women who met criteria for probable depression (Edinburgh Postnatal Depression Scale > 9) and those who did not meet criteria for probable depression at 8‐weeks postpartum.Findings.  Women with depressive symptoms at 8‐weeks postpartum had significantly lower perceptions of relationship‐specific and postpartum‐specific partner support and significantly higher levels of relationship conflict than women with no depressive symptoms. Multiple regression analyses revealed that three variables, perceived social integration, partner encouragement to obtain help when needed, and partner agreed with infant care, significantly explained the variance in Edinburgh Postnatal Depression Scale scores.Conclusions.  Maternal perceptions of social integration and partner provision of problem‐focused informational support and positive feedback are important in determining maternal mental health. Therefore, in the antenatal period healthcare professionals should teach couples appropriate ways to provide feedback and communicate expectations, especially those relating to infant care strategies. The importance of appraisal and emotional support should be highlighted in order to foster maternal feelings of acceptance and being cared for. Partners should also be encouraged to participate actively in household tasks and infant care activities to protect the mother from becoming overwhelmed.
Patterns in the assembly of an island plant community
Authors: Burns K. C. 
Published: November 2006

AbstractAim  To test for patterns in the assembly of an island plant community.Location  Islands off the west coast of Vancouver Island, British Columbia, Canada.Methods  Twenty‐seven islands were visited by boat, and the abundance of six woody angiosperm species was quantified. Null models were then used to test whether: (1) some species co‐occur less than expected by chance (i.e. co‐occurrence assembly rule), (2) the incidence and abundance of some species are inversely related to the abundance of other species (i.e. incidence assembly rule), and (3) support for assembly rules precludes evidence for nestedness, which refers to a pattern in species composition in which the species present on depauperate islands form regular subsets of those occurring on progressively more diverse islands.Results  Most species co‐occurred with other species at frequencies expected by chance. However, one species (Sambucus racemosa) co‐occurred with other species less frequently than randomized expectations. The observed incidence and abundance patterns of most species were also consistent with randomized patterns. However, the incidence and abundance of S. racemosa declined with the abundance of other plant species. Weak, variable support was found for nestedness of the total plant community. However, stronger, consistent support was found after removing S. racemosa from the matrix prior to analyses.Main conclusions  Most species were assembled on islands in a manner consistent with randomized expectations. However, non‐random distributional patterns were observed in one species whose distribution was consistent with the hypothesis that competition limits the assembly of island communities.
Ecology and biogeography of plant communities associated with the post Plio‐Pleistocene relictRhododendron ponticumsubsp.baeticumin southern Spain
Authors: Mejías José A. , Arroyo Juan , Marañón Teodoro 
Published: November 2006

AbstractAims Rhododendron ponticumL. is reputed to be a post Plio‐Pleistocene relict plant species with a disjunct distribution that comprises the Iberian Peninsula to the west and the Euxinian region plus some restricted Mediterranean areas to the east. We analysed the ecological range (of subsp.baeticum) in the western area (Aljibe Mountains, north of the Strait of Gibraltar) to understand the factors determining the present area limitation.Location Sierra del Aljibe, north of the Strait of Gibraltar (Iberian Peninsula).Methods We selected 20 riparian sites whereR. ponticumis common, and compiled data on the ecological diversity of associated woody species and ferns. We established a 500‐m main transect in each site, along the stream or river course, in which we placed five 20‐m‐long plots at regular intervals. We recorded physiographic habitat features, woody plants and fern abundance, and the number ofR. ponticumindividuals.Results Rhododendron ponticumin southern Spain is restricted to riparian forests in acidic soils (pH 4.0–6.4), and is mainly found on the banks of inclined and enclosed streams. In our inventory we recorded 59 woody taxa and 12 ferns, withR. ponticumbeing the dominant species of the understorey (mean abundance 78.6%). The communities are characterized by a high incidence of the humid warm temperate element, both in number of species (18.8 ± 3.7 per site) and abundance; meanwhile, the presence of the modern Mediterranean element (mean number of species 3.4 ± 3.8 per site) appears to be favoured by disturbance. These ecological–historical groups of taxa also show distinct patterns of typological habit, frequency of endemism, infrageneric diversity and geographical range. Populations ofR. ponticumare characterized by a very variable density of seedlings in many sites, and the virtual lack of juveniles.Main conclusions Riparian forests of the Aljibe Mountains constitute a refuge forR. ponticumwhere the species persists, but populations appear to be in decline. The narrow ecological range ofR. ponticumin the area strongly contrasts with its wide amplitude in the eastern natural area, mainly the Euxinian region, whereR. ponticumprobably finds better conditions due to the environmental heterogeneity of the region, and the lack of a hot dry season.