1,151 research outputs found
Dusty tails of evaporating exoplanets. II. Physical modelling of the KIC 12557548b light curve
Evaporating rocky exoplanets, such as KIC 12557548b, eject large amounts of
dust grains, which can trail the planet in a comet-like tail. When such objects
occult their host star, the resulting transit signal contains information about
the dust in the tail. We aim to use the detailed shape of the Kepler light
curve of KIC 12557548b to constrain the size and composition of the dust grains
that make up the tail, as well as the mass loss rate of the planet. Using a
self-consistent numerical model of the dust dynamics and sublimation, we
calculate the shape of the tail by following dust grains from their ejection
from the planet to their destruction due to sublimation. From this dust cloud
shape, we generate synthetic light curves (incorporating the effects of
extinction and angle-dependent scattering), which are then compared with the
phase-folded Kepler light curve. We explore the free-parameter space thoroughly
using a Markov chain Monte Carlo method. Our physics-based model is capable of
reproducing the observed light curve in detail. Good fits are found for initial
grain sizes between 0.2 and 5.6 micron and dust mass loss rates of 0.6 to 15.6
M_earth/Gyr (2-sigma ranges). We find that only certain combinations of
material parameters yield the correct tail length. These constraints are
consistent with dust made of corundum (Al2O3), but do not agree with a range of
carbonaceous, silicate, or iron compositions. Using a detailed, physically
motivated model, it is possible to constrain the composition of the dust in the
tails of evaporating rocky exoplanets. This provides a unique opportunity to
probe to interior composition of the smallest known exoplanets.Comment: 18 pages, 11 figures, A&A accepte
Barriers to home care for terminally ill Turkish and Moroccan migrants, perceived by GPs and nurses: a survey
BACKGROUND: Previous qualitative research proved that relatives of elderly terminally ill Turkish and Moroccan immigrants experience several barriers to the use of Dutch professional home care. The aim of this study was to explore how general practitioners and home care nurses perceive the home care for terminally ill Turkish and Moroccan migrants and their families in the Netherlands. METHODS: Questionnaires were sent to home care organizations and GPs working in areas where most of these migrants are living. 93 nurses and 78 GPs provided information about their experiences and opinions regarding home care for this group of patients. The data were analyzed by descriptive statistics. RESULTS: GPs refer relatively few patients from these migrant groups to home care. They often find it difficult to assess the needs of these patients and their families. In 40% of the GPs' cases in which terminally ill Turkish and Moroccan migrants were not referred to home care, the GP regretted this afterwards: the patients had not received sufficient qualified care, and their informal carers had often become overburdened. In addition, home care nurses often express dissatisfaction with the home care given to terminally ill Turkish or Moroccan patients, because of communication problems, the patients' lack of knowledge of the disease, or difficulties in making suitable appointments with the patient or with the family. CONCLUSIONS: Nurses and GPs cite chiefly similar factors influencing access to and use of home care as family members did in a previous study. However, according to GPs and nurses, the main barrier to the use of home care concerns communication problems, while relatives cited the preference for family care as the main reason for abstaining from the use of home care. (aut. ref.
Perspectives on care and communication involving incurably ill Turkish and Moroccan patients, relatives and professionals: a systematic literature review
<p>Abstract</p> <p>Background</p> <p>Our aim was to obtain a clearer picture of the relevant care experiences and care perceptions of incurably ill Turkish and Moroccan patients, their relatives and professional care providers, as well as of communication and decision-making patterns at the end of life. The ultimate objective is to improve palliative care for Turkish and Moroccan immigrants in the Netherlands, by taking account of socio-cultural factors in the guidelines for palliative care.</p> <p>Methods</p> <p>A systematic literature review was undertaken. The data sources were seventeen national and international literature databases, four Dutch journals dedicated to palliative care and 37 websites of relevant national and international organizations. All the references found were checked to see whether they met the structured inclusion criteria. Inclusion was limited to publications dealing with primary empirical research on the relationship between socio-cultural factors and the health or care situation of Turkish or Moroccan patients with an oncological or incurable disease. The selection was made by first reading the titles and abstracts and subsequently the full texts. The process of deciding which studies to include was carried out by two reviewers independently. A generic appraisal instrument was applied to assess the methodological quality.</p> <p>Results</p> <p>Fifty-seven studies were found that reported findings for the countries of origin (mainly Turkey) and the immigrant host countries (mainly the Netherlands). The central themes were experiences and perceptions of family care, professional care, end-of-life care and communication. Family care is considered a duty, even when such care becomes a severe burden for the main female family caregiver in particular. Professional hospital care is preferred by many of the patients and relatives because they are looking for a cure and security. End-of-life care is strongly influenced by the continuing hope for recovery. Relatives are often quite influential in end-of-life decisions, such as the decision to withdraw or withhold treatments. The diagnosis, prognosis and end-of-life decisions are seldom discussed with the patient, and communication about pain and mental problems is often limited. Language barriers and the dominance of the family may exacerbate communication problems.</p> <p>Conclusions</p> <p>This review confirms the view that family members of patients with a Turkish or Moroccan background have a central role in care, communication and decision making at the end of life. This, in combination with their continuing hope for the patient’s recovery may inhibit open communication between patients, relatives and professionals as partners in palliative care. This implies that organizations and professionals involved in palliative care should take patients’ socio-cultural characteristics into account and incorporate cultural sensitivity into care standards and care practices<it>.</it></p
Role of institutional and socio-economic factors on adoption, dis-adoption and non-adoption of soil and water conservation technologies: Empirical evience from the North Western Ethiopia highlands.
ABSTRACT In order to combat land degradation in the form of water erosion and fertility depletion in the Central Rift Valley (CRV) of Ethiopia farmers are of crucial importance. If they perceive land degradation as a problem they will be more willing to invest in land management measures. This study presents farmers’ perceptions of land degradation, respective investments, and factors influencing their investments in land. In this study, water erosion and fertility depletion are taken as main indicators of land degradation. Results show that farmers perceive water erosion and soil fertility depletion as problems that have intensified over the last decade. However, despite awareness of these problems, farmers’ investments to control soil erosion and soil fertility depletion are very limited. This study shows that the major factors that positively influence farmers’ investments in land management practices are households’ resource endowments, access to information, social capital and availability of family labor. For sustainable land management strategies this implies that these should (i) be integrated within a comprehensive rural development strategy that generates improvements of farmers’ livelihoods and their financial capacity, (ii) trigger social capital and create enabling conditions for farmers to participate in different groups, cross site visits and farmer-to-farmer experience sharing, and (iii) stimulate collective action within the villages in order to enhance access to labor which is crucial for carrying out land management practices. Key words: Land degradation, farmers’ investments, sustainable land management, socioeconomic factors, factor analysi
Genotypic diversity effects on biomass production in native perennial bioenergy cropping systems
Citation: Morris, G. P., Hu, Z., Grabowski, P. P., Borevitz, J. O., de Graaff, M. A., Miller, R. M., & Jastrow, J. D. (2016). Genotypic diversity effects on biomass production in native perennial bioenergy cropping systems. GCB Bioenergy. doi:10.1111/gcbb.12309Article: Version of RecordThe perennial grass species that are being developed as biomass feedstock crops harbor extensive genotypic diversity, but the effects of this diversity on biomass production are not well understood. We investigated the effects of genotypic diversity in switchgrass (Panicum virgatum) and big bluestem (Andropogon gerardii) on perennial biomass cropping systems in two experiments conducted over 2008-2014 at a 5.4-ha fertile field site in northeastern Illinois, USA. We varied levels of switchgrass and big bluestem genotypic diversity using various local and nonlocal cultivars - under low or high species diversity, with or without nitrogen inputs - and quantified establishment, biomass yield, and biomass composition. In one experiment ('agronomic trial'), we compared three switchgrass cultivars in monoculture to a switchgrass cultivar mixture and three different species mixtures, with or without N fertilization. In another experiment ('diversity gradient'), we varied diversity levels in switchgrass and big bluestem (1, 2, 4, or 6 cultivars per plot), with one or two species per plot. In both experiments, cultivar mixtures produced yields equivalent to or greater than the best cultivars. In the agronomic trial, the three switchgrass mixture showed the highest production overall, though not significantly different than best cultivar monoculture. In the diversity gradient, genotypic mixtures had one-third higher biomass production than the average monoculture, and none of the monocultures were significantly higher yielding than the average mixture. Year-to-year variation in yields was lowest in the three-cultivar switchgrass mixtures and Cave-In-Rock (the southern Illinois cultivar) and also reduced in the mixture of switchgrass and big bluestem relative to the species monocultures. The effects of genotypic diversity on biomass composition were modest relative to the differences among species and genotypes. Our findings suggest that local genotypes can be included in biomass cropping systems without compromising yields and that genotypic mixtures could help provide high, stable yields of high-quality biomass feedstocks. © 2015 John Wiley & Sons Ltd
Myocardial injury after noncardiac surgery and its association with short-term mortality
Background: To identify patients at risk for postoperative myocardial injury and death, measuring cardiac troponin routinely after noncardiac surgery has been suggested. Such monitoring was implemented in our hospital. The aim of this study was to determine the predictive value of postoperative myocardial injury, as measured by troponin elevation, on 30-day mortality after noncardiac surgery. Methods and Results: This observational, single-center cohort study included 2232 consecutive intermediate- to highrisk noncardiac surgery patients aged ≥60 years who underwent surgery in 2011. Troponin was measured on the first 3 postoperative days. Log binomial regression analysis was used to estimate the association between postoperative myocardial injury (troponin I level >0.06 μg/L) and all-cause 30-day mortality. Myocardial injury was found in 315 of 1627 patients in whom troponin I was measured (19%). All-cause death occurred in 56 patients (3%). The relative risk of a minor increase in troponin (0.07-0.59 μg/L) was 2.4 (95% confidence interval, 1.3-4.2; P<0.01), and the relative risk of a 10- to 100-fold increase in troponin (≥0.60 μg/L) was 4.2 (95% confidence interval, 2.1-8.6; P<0.01). A myocardial infarction according to the universal definition was diagnosed in 10 patients (0.6%), of whom 1 (0.06%) had ST-segment elevation myocardial infarction. Conclusions: Postoperative myocardial injury is an independent predictor of 30-day mortality after noncardiac surgery. Implementation of postoperative troponin monitoring as standard of care is feasible and may be helpful in improving the prognosis of patients undergoing noncardiac surgery.</p
A systematic review of the energy and climate impacts of teleworking
Information and communication technologies (ICTs) increasingly enable employees to work from home and other locations (‘teleworking’). This study explores the extent to which teleworking reduces the need to travel to work and the consequent impacts on economy-wide energy consumption.
Methods/Design: The paper provides a systematic review of the current state of knowledge of the energy impacts of teleworking. This includes the energy savings from reduced commuter travel and the indirect impacts on energy consumption associated with changes in non-work travel and home energy consumption. The aim is to identify the conditions under which teleworking leads to a net reduction in economy-wide energy consumption, and the circumstances where benefits may be outweighed by unintended impacts. The paper synthesises the results of 39 empirical studies, identified through a comprehensive search of 9,000 published articles.
Review results/Synthesis: Twenty six of the 39 studies suggest that teleworking reduces energy use, and only eight studies suggest that teleworking increases, or has a neutral impact on energy use. However, differences in the methodology, scope and assumptions of the different studies make it difficult to estimate ‘average’ energy savings. The main source of savings is the reduced distance travelled for commuting, potentially with an additional contribution from lower office energy consumption. However, the more rigorous studies that include a wider range of impacts (e.g. non-work travel or home energy use) generally find smaller savings.
Discussion: Despite the generally positive verdict on teleworking as an energy-saving practice, there are numerous uncertainties and ambiguities about its actual or potential benefits. These relate to the extent to which teleworking may lead to unpredictable increases in non-work travel and home energy use that may outweigh the gains from reduced work travel. The available evidence suggests that economy-wide energy savings are typically modest, and in many circumstances could be negative or non-existent
Myocardial injury after noncardiac surgery and its association with short-term mortality
Background: To identify patients at risk for postoperative myocardial injury and death, measuring cardiac troponin routinely after noncardiac surgery has been suggested. Such monitoring was implemented in our hospital. The aim of this study was to determine the predictive value of postoperative myocardial injury, as measured by troponin elevation, on 30-day mortality after noncardiac surgery. Methods and Results: This observational, single-center cohort study included 2232 consecutive intermediate- to highrisk noncardiac surgery patients aged ≥60 years who underwent surgery in 2011. Troponin was measured on the first 3 postoperative days. Log binomial regression analysis was used to estimate the association between postoperative myocardial injury (troponin I level >0.06 μg/L) and all-cause 30-day mortality. Myocardial injury was found in 315 of 1627 patients in whom troponin I was measured (19%). All-cause death occurred in 56 patients (3%). The relative risk of a minor increase in troponin (0.07-0.59 μg/L) was 2.4 (95% confidence interval, 1.3-4.2; P<0.01), and the relative risk of a 10- to 100-fold increase in troponin (≥0.60 μg/L) was 4.2 (95% confidence interval, 2.1-8.6; P<0.01). A myocardial infarction according to the universal definition was diagnosed in 10 patients (0.6%), of whom 1 (0.06%) had ST-segment elevation myocardial infarction. Conclusions: Postoperative myocardial injury is an independent predictor of 30-day mortality after noncardiac surgery. Implementation of postoperative troponin monitoring as standard of care is feasible and may be helpful in improving the prognosis of patients undergoing noncardiac surgery.</p
The effect of intrathecal bupivacaine/morphine on quality of recovery in robot-assisted radical prostatectomy: a randomised controlled trial
Robot-assisted radical prostatectomy causes discomfort in the immediate postoperative period. This randomised controlled trial investigated if intrathecal bupivacaine/morphine, in addition to general anaesthesia, could be beneficial for the postoperative quality of recovery. One hundred and fifty-five patients were randomly allocated to an intervention group that received intrathecal 12.5 mg bupivacaine/300 μg morphine (20% dose reduction in patients > 75 years) or a control group receiving a subcutaneous sham injection and an intravenous loading dose of 0.1 mg.kg−1 morphine. Both groups received standardised general anaesthesia and the same postoperative analgesic regimen. The primary outcome was a decrease in the Quality of Recovery-15 (QoR-15) questionnaire score on postoperative day 1. The intervention group (n = 76) had less reduction in QoR-15 on postoperative day 1; median (IQR [range]) 10% (1–8 [−60% to 50%]) vs. 13% (5–24 [−6% to 50%]), p = 0.019, and used less morphine during the admission; 2 mg (1–7 [0–41 mg]) vs. 15 mg (12–20 [8–61 mg]), p < 0.001. Furthermore, they perceived lower pain scores during exertion; numeric rating scale (NRS) 3 (1–6 [0–9]) vs. 5 (3–7 [0–9]), p = 0.001; less bladder spasms (NRS 1 (0–2 [0–10]) vs. 2 (0–5 [0–10]), p = 0.001 and less sedation; NRS 2 (0–3 [0–10]) vs. 3 (2–6 [0–10]), p = 0.005. Moreover, the intervention group used less rescue medication. Pruritus was more severe in the intervention group; NRS 4 (1–7 [0–10]) vs. 0 (0–1 [0–10]), p = 0.000. We conclude that despite a modest increase in the incidence of pruritus, multimodal pain management with intrathecal bupivacaine/morphine remains a viable option for robot-assisted radical prostatectomy
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