3,600 research outputs found
How CMB and large-scale structure constrain chameleon interacting dark energy
We explore a chameleon type of interacting dark matter-dark energy scenario
in which a scalar field adiabatically traces the minimum of an effective
potential sourced by the dark matter density. We discuss extensively the effect
of this coupling on cosmological observables, especially the parameter
degeneracies expected to arise between the model parameters and other
cosmological parameters, and then test the model against observations of the
cosmic microwave background (CMB) anisotropies and other cosmological probes.
We find that the chameleon parameters and , which determine
respectively the slope of the scalar field potential and the dark matter-dark
energy coupling strength, can be constrained to and using CMB data alone. The latter parameter in particular is constrained
only by the late Integrated Sachs-Wolfe effect. Adding measurements of the
local Hubble expansion rate tightens the bound on by a factor of
two, although this apparent improvement is arguably an artefact of the tension
between the local measurement and the value inferred from Planck data in
the minimal CDM model. The same argument also precludes chameleon
models from mimicking a dark radiation component, despite a passing similarity
between the two scenarios in that they both delay the epoch of matter-radiation
equality. Based on the derived parameter constraints, we discuss possible
signatures of the model for ongoing and future large-scale structure surveys.Comment: 25 pages, 6 figure
Development and validation of risk profiles of West African rural communities facing multiple natural hazards
West Africa has been described as a hotspot of climate change. The reliance on rain-fed agriculture by over 65% of the population means that vulnerability to climatic hazards such as droughts, rainstorms and floods will continue. Yet, the vulnerability and risk levels faced by different rural social-ecological systems (SES) affected by multiple hazards are poorly understood. To fill this gap, this study quantifies risk and vulnerability of rural communities to drought and floods. Risk is assessed using an indicator-based approach. A stepwise methodology is followed that combines participatory approaches with statistical, remote sensing and Geographic Information System techniques to develop community level vulnerability indices in three watersheds (Dano, Burkina Faso; Dassari, Benin; Vea, Ghana). The results show varying levels of risk profiles across the three watersheds. Statistically significant high levels of mean risk in the Dano area of Burkina Faso are found whilst communities in the Dassari area of Benin show low mean risk. The high risk in the Dano area results from, among other factors, underlying high exposure to droughts and rainstorms, longer dry season duration, low caloric intake per capita, and poor local institutions. The study introduces the concept of community impact score (CIS) to validate the indicator-based risk and vulnerability modelling. The CIS measures the cumulative impact of the occurrence of multiple hazards over five years. 65.3% of the variance in observed impact of hazards/CIS was explained by the risk models and communities with high simulated disaster risk generally follow areas with high observed disaster impacts. Results from this study will help disaster managers to better understand disaster risk and develop appropriate, inclusive and well integrated mitigation and adaptation plans at the local level. It fulfills the increasing need to balance global/regional assessments with community level assessments where major decisions against risk are actually taken and implemented
Use of Marketing Tools in the Slovakian Forest Biomass Trade
The fast growing renewable energy market offers opportunities for the traditional forest sector both in Europe in general and Slovakia in particular. The reasoning behind this is twofold. First, in last decade the renewable energy business has gained significant attention. Among other reasons, this is due to the goal of a reduction of greenhouse gas emissions. Second, changes in downstream markets due to financial crises have put pressure on forest enterprises to redefine their sales portfolios. As marketing can help to realize new opportunities for forestry, the aim of this research study is to shed more light on how forestry enterprises in Slovakia use marketing tools in the trade of forest biomass, the main renewable energy source available to Slovakia. Due to its explorative nature, a case study research design with qualitative methodology has been applied.
The capacity for use of marketing tools by (state and private) forest enterprises was explored through in-depth personal interviews analyzed with the help of content analysis. By presenting four detailed cases, the results show that in the forest biomass trade, the forest enterprises all used a marketing mix of »The 5Ps« (product, price, place, promotion, and people) and consequently applied a set of tools different from those observed in other industry sectors
Determinants of Household Participation in Rural Development Projects
This paper provides evidence for determinants of households participation in rural development projects. Study findings are based on qualitative analysis and logistic estimation of a random utility model. Households with higher incomes appear less likely to participate; those with more labor are more likely. Availability of activities of interest to community members could enhance participation.Community/Rural/Urban Development,
Transition to adult services for children and young people with palliative care needs : a systematic review
Objective: To evaluate the evidence on the transition process from child to adult services for young people with palliative care needs.
Design: Systematic review
Setting: Child and adult services and interface between healthcare providers.
Patients: Young people aged 13 to 24 years with palliative care conditions in the process of transition.
Main outcome measures: Young people and their families’ experiences of transition, the process of transition between services and its impact on continuity of care, and models of good practice.
Results: 92 studies included. Papers on transition services were of variable quality when applied to palliative care contexts. Most focused on common life threatening and life limiting conditions. No standardised transition programme identified and most guidelines used to develop transition services were not evidence based. Most studies on transition programmes were predominantly condition-specific (e.g. cystic fibrosis, cancer) services. Cystic fibrosis services offered high quality transition with the most robust empirical evaluation. There were differing condition-dependent viewpoints on when transition should occur but agreement on major principles guiding transition
planning and probable barriers. There was evidence of poor continuity between child and adult providers with most originating from within child settings.
Conclusions: Palliative care was not, in itself, a useful concept for locating transition-related evidence. It is not possible to evaluate the merits of the various transition models for palliative care contexts, or their effects on
continuity of care, as there are no long-term outcome data to measure their effectiveness. Use of validated outcome measures would facilitate research and service development
Quality requirements for reclaimed/recycled water
Water used during current and previous space missions has been either carried or made aloft. Future human space endeavors will require some form of water reclamation and recycling. There is little experience in the U.S. space program with this technology. Water reclamation and recycling constitute engineering challenges of the broadest nature that will require an intensive research and development effort if this technology is to mature in time for practical use on the proposed U.S. Space Station. In order for this to happen, reclaimed/recycled water specifications will need to be devised to guide engineering development. Present NASA Potable Water Specifications are not applicable to reclaimed or recycled water. Adequate specifications for ensuring the quality of the reclaimed or recycled potable water system is reviewed, limitations of present water specifications are examined, world experience with potable water reclamation/recycling systems and systems analogs is reviewed, and an approach to developing pertinent biomedical water specifications for spacecraft is presented. Space Station water specifications should be designed to ensure the health of all likely spacecraft inhabitants including man, animals, and plants
Recommended from our members
DNA demethylation by ROS1a in rice vegetative cells promotes methylation in sperm.
Epigenetic reprogramming is required for proper regulation of gene expression in eukaryotic organisms. In Arabidopsis, active DNA demethylation is crucial for seed viability, pollen function, and successful reproduction. The DEMETER (DME) DNA glycosylase initiates localized DNA demethylation in vegetative and central cells, so-called companion cells that are adjacent to sperm and egg gametes, respectively. In rice, the central cell genome displays local DNA hypomethylation, suggesting that active DNA demethylation also occurs in rice; however, the enzyme responsible for this process is unknown. One candidate is the rice REPRESSOR OF SILENCING 1a (ROS1a) gene, which is related to DME and is essential for rice seed viability and pollen function. Here, we report genome-wide analyses of DNA methylation in wild-type and ros1a mutant sperm and vegetative cells. We find that the rice vegetative cell genome is locally hypomethylated compared with sperm by a process that requires ROS1a activity. We show that many ROS1a target sequences in the vegetative cell are hypomethylated in the rice central cell, suggesting that ROS1a also demethylates the central cell genome. Similar to Arabidopsis, we show that sperm non-CG methylation is indirectly promoted by DNA demethylation in the vegetative cell. These results reveal that DNA glycosylase-mediated DNA demethylation processes are conserved in Arabidopsis and rice, plant species that diverged 150 million years ago. Finally, although global non-CG methylation levels of sperm and egg differ, the maternal and paternal embryo genomes show similar non-CG methylation levels, suggesting that rice gamete genomes undergo dynamic DNA methylation reprogramming after cell fusion
How do utterance measures predict raters’ perceptions of fluency in French as a second language?
While the research literature on second language (L2) fluency is replete with descriptions of fluency and its influence with regard to English as an additional language, little is known about what fluency features influence judgments of fluency in L2 French. This study reports the results of an investigation that analyzed the relationship between utterance fluency measures and raters’ perceptions of L2 fluency in French using mixed-effects modeling. Participants were 40 adult learners of French at varying levels of proficiency, studying in a university immersion context. Speech performances were collected on three different types of narrative tasks. Four utterance fluency measures were extracted from each performance. Eleven untrained judges rated the speech performances and we examined which utterance fluency measures are the best predictors of the scores awarded by the raters. The mean length of runs and articulation rate proved to be the most influential factors in raters’ judgments, while the frequency of pauses played a less important role. The length of pauses was positively related to fluency scores indicating a prominent cross-linguistic variation specific to French. The relative importance of the utterance measures in predicting fluency ratings, however, was found to vary across tasks
- …