2,970 research outputs found
Thermal Gradient Changes Caused by Water in the Soil
The heat flow density data published in the Geothermal Atlas of Europe (1992) show relatively high values for temperature gradients measured in holes in the SW area (Portugal and Spain) of the Iberian Peninsula.
This study tries to explain this fact based in the presence of water at relatively high temperatures outside the holes where the measurements were made, and the inclination of strata, derived from samples taken from the boreholes. We used a two-dimensional numerical model based on the finite volume method. Equations governing the transfer of energy by conduction and advection and fluid flow, were solved.
Thermal conductivity values of the rocks and water may vary spatially as well as the porosity. Thermal conductivity values were measured but values of the hydraulic conductivity and porosity are unknown. Due to this fact, the models are tested with different values of these parameters.
The heat flow density value considered for the region is 60 mWm-2 and the thermal gradient is calculated using the value of thermal conductivity. The results obtained with the models are compared with those published. Different solutions can be obtained for a given hole
Improving Pediatric Nursesâ Knowledge of Postoperative Care for the Pediatric Patient Undergoing Surgical Correction of Pectus Excavatum: A Quality Improvement Project
Abstract
Surgical correction for the chest wall deformity known as Pectus Excavatum (PE) is often performed during adolescence for patients exhibiting cardiac, respiratory, and psychological problems. The established surgery performed to correct PE is a thoracoscopic-assisted minimally invasive repair of pectus excavatum (MIRPE) or Nuss procedure. The clinical care of patients who undergo the Nuss procedure is mainly focused on the postoperative pain management related to the constant pressure from the bar(s) on the sternum. A quality improvement project was developed with the aim to improve the nursesâ knowledge of the postoperative care for the pediatric patient undergoing a Nuss procedure. The project was set in a stand-alone urban pediatric hospital. Participants included pediatric nurses who work in the surgical unit and nurse practitioners who manage pediatric surgical patients.
A comprehensive study search was conducted using CINAHL and MEDLINE (ProQuest) to identify research studies from the past five years that have evaluated the effectiveness of the nursesâ knowledge of postoperative care for patients undergoing chest wall corrective surgery. The six research studies identified as relevant for review investigated nurseâs knowledge and attitudes of postoperative pain management in the pediatric patient and the effectiveness of enhanced recovery pathways to improve patient outcomes. The quality improvement project demonstrated that the implementation of a targeted education program for the care of the pediatric patient who undergoes a Nuss procedure improved the clinicianâs knowledge and attitudes that positively impact pain management practices and improve patient outcomes
Detecting groundwater discharge dynamics from point-to-catchment scale in a lowland stream : Combining hydraulic and tracer methods
Acknowledgements. We would like to thank members of the Northern Rivers Institute, Aberdeen University, for helpful discussions of data. We also thank Lars Rasmussen, Jolanta Kazmierczak and Charlotte Ditlevsen for help in the field. This study is part of the Hydrology Observatory, HOBE (http://www.hobe.dk), funded by the Villum Foundation and was as well funded by the Aarhus University Research Foundation.Peer reviewedPublisher PD
Molecular theory of hydrophobic mismatch between lipids and peptides
Effects of the mismatch between the hydrophobic length, d, of transmembrane
alpha helices of integral proteins and the hydrophobic thickness, D_h, of the
membranes they span are studied theoretically utilizing a microscopic model of
lipids. In particular, we examine the dependence of the period of a lamellar
phase on the hydrophobic length and volume fraction of a rigid, integral,
peptide. We find that the period decreases when a short peptide, such that
d<D_h, is inserted. More surprising, we find that the period increases when a
long peptide, such that d>D_h, is inserted. The effect is due to the
replacement of extensible lipid tails by rigid peptide. As the peptide length
is increased, the lamellar period continues to increase, but at a slower rate,
and can eventually decrease. The amount of peptide which fails to incorporate
and span the membrane increases with the magnitude of the hydrophobic mismatch
|d-D_h|. We explicate these behaviors which are all in accord with experiment.
Predictions are made for the dependence of the tilt of a single trans-membrane
alpha helix on hydrophobic mismatch and helix density.Comment: 14 pages, 5 figure
Pronounced impairment of activities of daily living in posterior cortical atrophy
Introduction : The impact of several dementia syndromes on activities of daily living (ADLs) has been well documented, but no study has yet investigated functional ability in posterior cortical atrophy (PCA). The primarily visual nature of deficits in this condition is likely to have a pronounced impact on ADLs. Objective : The aim of this study was to profile functional change in PCA and identify predictors of change. Method : Twenty-nine PCA patients and 25 patients with typical Alzheimerâs disease (AD) and their caregivers were included in this cross-sectional study. ADLs were assessed using the Disability Assessment for Dementia (DAD), administered to caregivers, assessing basic ADLs (e.g., eating, dressing) and instrumental ADLs (e.g., managing finances, meal preparation). The predictive utility of cognitive domains (Addenbrookeâs Cognitive Examination), behavioural impairment (Cambridge Behavioural Inventory-Revised) and demographic variables on ADL ability was also examined. Results : PCA patients showed significantly reduced total ADL scores compared to AD patients (medium effect size, d = â0.7; p 0.05). A model combining patient mood, disinhibition, apathy, symptom duration, and memory and attention/orientation scores explained the variance of scores in functional decline (61.2%), but the key factor predicting ADL scores was attention/orientation (p = 0.048). Conclusion : This study shows the profound impact of PCA on ADLs and factors underpinning patientsâ disability. Attention/orientation deficits were found to correlate and contribute to variance in ADL scores. Future work to develop tailored interventions to manage ADL impairment in PCA should take these findings into account
Forgetting complex propositions
This paper uses possible-world semantics to model the changes that may occur
in an agent's knowledge as she loses information. This builds on previous work
in which the agent may forget the truth-value of an atomic proposition, to a
more general case where she may forget the truth-value of a propositional
formula. The generalization poses some challenges, since in order to forget
whether a complex proposition is the case, the agent must also lose
information about the propositional atoms that appear in it, and there is no
unambiguous way to go about this.
We resolve this situation by considering expressions of the form
, which quantify over all possible (but
minimal) ways of forgetting whether . Propositional atoms are modified
non-deterministically, although uniformly, in all possible worlds. We then
represent this within action model logic in order to give a sound and complete
axiomatization for a logic with knowledge and forgetting. Finally, some
variants are discussed, such as when an agent forgets (rather than
forgets whether ) and when the modification of atomic facts is done
non-uniformly throughout the model
Voluntary food sharing in pinyon jays: The role of reciprocity and dominance
Food sharing offers a clear example of prosocial behavior, in which one individualâs actions benefit another. Researchers have proposed a range of hypotheses that explain why food sharing may occur among unrelated individuals. Two such hypotheses, reciprocity and dominance, have been tested in many species, including fish, corvids, rats, bats, and primates, showing that (1) recipients sometimes reciprocate sharing back to previous donors and (2) dominant individuals share more than subordinates. Although primates dominate the study of prosocial behavior, active donation of food is actually quite rare in primates. In contrast, several corvid species spontaneously share food much more frequently. Here, we explored the role of reciprocity and dominance in spontaneous food sharing among male pinyon jays (Gymnorhinus cyanocephalus); a North American corvid species that exhibits high levels of social complexity. Unlike much of the previous work, we tested prosocial behavior among unrelated, non-pair bonded adults. We observed high levels of active sharing, and donors showed clear preferences with whom they shared. We found no evidence that pinyon jays reciprocated shares in either the short or long term. This was true for both sharing within-dyads (direct reciprocity) and sharing irrespective of most recent partner identity (generalized reciprocity). However, dominance influenced sharing in one of our groups, with dominant individuals sharing more than subordinates. This study highlights corvids as a fruitful model for the study of the proximate mechanisms underlying naturally occurring prosocial behaviors
Voluntary food sharing in pinyon jays: The role of reciprocity and dominance
Food sharing offers a clear example of prosocial behavior, in which one individualâs actions benefit another. Researchers have proposed a range of hypotheses that explain why food sharing may occur among unrelated individuals. Two such hypotheses, reciprocity and dominance, have been tested in many species, including fish, corvids, rats, bats, and primates, showing that (1) recipients sometimes reciprocate sharing back to previous donors and (2) dominant individuals share more than subordinates. Although primates dominate the study of prosocial behavior, active donation of food is actually quite rare in primates. In contrast, several corvid species spontaneously share food much more frequently. Here, we explored the role of reciprocity and dominance in spontaneous food sharing among male pinyon jays (Gymnorhinus cyanocephalus); a North American corvid species that exhibits high levels of social complexity. Unlike much of the previous work, we tested prosocial behavior among unrelated, non-pair bonded adults. We observed high levels of active sharing, and donors showed clear preferences with whom they shared. We found no evidence that pinyon jays reciprocated shares in either the short or long term. This was true for both sharing within-dyads (direct reciprocity) and sharing irrespective of most recent partner identity (generalized reciprocity). However, dominance influenced sharing in one of our groups, with dominant individuals sharing more than subordinates. This study highlights corvids as a fruitful model for the study of the proximate mechanisms underlying naturally occurring prosocial behaviors
Where are the tropical plants? A call for better inclusion of tropical plants in studies investigating and predicting the effects of climate change
Tropical plant species are systematically underrepresented in large-scale analyses or synthesis looking at the potential effects of global climate change. The reason being that we simply donât know enough about the distributions and ecologies of most tropical plant species to predict their fate under climate change. This gaping hole in our knowledge is extremely worrisome given the high diversity of tropical plants, the crucial roles that they play in supporting global diversity and ecosystem function, and the elevated threats that climate change may pose to tropical species in general.  </p
- âŠ