1,510 research outputs found
Coordination of Care by Primary Care Practices: Strategies, Lessons and Implications
Documents successful strategies for coordinating care within primary care settings, including family and caregivers; with specialists; with hospital settings; and with community-based services. Discusses challenges, lessons learned, and implications
Edge Shear Flows and Particle Transport near the Density Limit in the HL-2A Tokamak
Edge shear flow and its effect on regulating turbulent transport have long
been suspected to play an important role in plasmas operating near the
Greenwald density limit . In this study, equilibrium profiles as well as
the turbulent particle flux and Reynolds stress across the separatrix in the
HL-2A tokamak are examined as is approached in ohmic L-mode discharges.
As the normalized line-averaged density is raised, the
shearing rate of the mean poloidal flow drops, and the
turbulent drive for the low-frequency zonal flow (the Reynolds power ) collapses. Correspondingly, the turbulent particle
transport increases drastically with increasing collision rates. The geodesic
acoustic modes (GAMs) gain more energy from the ambient turbulence at higher
densities, but have smaller shearing rate than low-frequency zonal flows. The
increased density also introduces decreased adiabaticity which not only
enhances the particle transport but is also related to a reduction in the
eddy-tilting and the Reynolds power. Both effects may lead to the cooling of
edge plasmas and therefore the onset of MHD instabilities that limit the plasma
density
Insights from a Subject Knowledge Enhancement Course for Creating New Chemistry and Physics Teachers
A recent Government response to shortages of new physics and chemistry teachers is the extended subject knowledge enhancement (SKE) course. Graduates without a physics or chemistry bachelor degree are prepared by an SKE course to enter a Postgraduate Certificate in Education (PGCE) programme to become science teachers with a physics or chemistry specialism. SKE courses challenge common assumptions about the nature of subject knowledge for teaching and who should teach it: school science educators or scientists? This article shares the SKE course model developed and taught by the Science Education team at Liverpool John Moores University, and some early insights into supporting subject knowledge development
Postnatal Depressive Symptoms Among Mothers and Fathers of Infants Born Preterm: Prevalence and Impacts on Children's Early Cognitive Function
OBJECTIVE:
Preterm birth is associated with lower cognitive functioning. One potential pathway is postnatal parental depression. The authors assessed depressive symptoms in mothers and fathers after preterm birth, and identified the impacts of both prematurity and parental depressive symptoms on children's early cognitive function.
METHOD:
Data were from the nationally representative Early Childhood Longitudinal Study, Birth Cohort (n = 5350). Depressive symptoms at 9 months were assessed by the Center for Epidemiologic Studies Depression Scale (CESD) and children's cognitive function at 24 months by the Bayley Short Form, Research Edition. Weighted generalized estimating equation models examined the extent to which preterm birth, and mothers' and fathers' postnatal depressive symptoms impacted children's cognitive function at 24 months, and whether the association between preterm birth and 24-month cognitive function was mediated by parental depressive symptoms.
RESULTS:
At 9 months, fathers of very preterm (<32 weeks gestation) and moderate/late preterm (32-37 weeks gestation) infants had higher CESD scores than fathers of term-born (≥37 weeks gestation) infants (p value = .02); preterm birth was not associated with maternal depressive symptoms. In multivariable analyses, preterm birth was associated with lower cognitive function at 24 months; this association was unaffected by adjustment for parental depressive symptoms. Fathers', but not mothers', postnatal depressive symptoms predicted lower cognitive function in the fully adjusted model (β = -0.11, 95% confidence interval, -0.18 to -0.03).
CONCLUSION:
Fathers of preterm infants have more postnatal depressive symptomology than fathers of term-born infants. Fathers' depressive symptoms also negatively impact children's early cognitive function. The national findings support early identification and treatment of fathers of preterm infants with depressive symptoms
Species-specific calcite production reveals Coccolithus pelagicus as the key calcifier in the Arctic Ocean
Through the production and export of their calcite coccoliths, coccolithophores form a key component of the global carbon cycle. Despite this key role, very little is known about the biogeochemical role of different coccolithophore species in terms of calcite production, and how these species will respond to future climate change and ocean acidification. Here, we present the first study to estimate species-specific calcite production, from samples collected in the Arctic Ocean and subarctic Iceland Basin in June 2012. We show that although the coccolithophorid Coccolithus pelagicus comprised only a small fraction of the total community in terms of abundance (2%), our estimates indicate that it was the major calcite producer in the Arctic Ocean and Iceland Basin (57% of total calcite production). In contrast, Emiliania huxleyi formed 27% of the total abundance and was responsible for only 20% of the calcite production. That C. pelagicus was able to dominate calcite production was due to its relatively high cellular calcite content compared with the other species present. Our results demonstrate, for the first time, the importance of investigating the complete coccolithophore community when considering pelagic calcite production, as relatively rare but heavily calcified species such as C. pelagicus can be the key calcite producers in mixed communities. Therefore, the response of C. pelagicus to ocean acidification and climate change has the potential to have a major impact on carbon cycling within the North Atlantic and Arctic Ocean
Protocol assessment issues in low duty cycle sensor networks: The switching energy
Energy assessment of MAC protocols for wireless sensor networks is generally based on the times of transmit, receive and sleep modes. The switching energy between two consecutive states is generally considered negligible with respect to them. Although such an assumption is valid for traditional wireless ad hoc networks, is this assumption valid also for low duty cycle wireless sensor networks? The primary objective of this work is to shed some light on relationships between node switching energy and node duty cycle over the total energy consumption. In order to achieve the target, initially, we revisit the energy spent in each state and transitions of three widespread hardware platforms for wireless sensor networks by direct measurements on the EYES node. Successively, we apply the values obtained to the SMAC protocol by using the OmNet++ simulator
Outer organic layer and internal repair mechanism protects pteropod Limacina helicina from ocean acidification
Scarred shells of polar pteropod Limacina helicina collected from the Greenland Sea in June 2012 reveal a history of damage, most likely failed predation, in earlier life stages. Evidence of shell fracture and subsequent re-growth is commonly observed in specimens recovered from the sub-Arctic and further afield. However, at one site within sea–ice on the Greenland shelf, shells that had been subject to mechanical damage were also found to exhibit considerable dissolution. It was evident that shell dissolution was localised to areas where the organic, periostracal sheet that covers the outer shell had been damaged at some earlier stage during the animal’s life. Where the periostracum remained intact, the shell appeared pristine with no sign of dissolution. Specimens which appeared to be pristine following collection were incubated for four days. Scarring of shells that received periostracal damage during collection only became evident in specimens that were incubated in waters undersaturated with respect to aragonite, ΩAr≤1. While the waters from which the damaged specimens were collected at the Greenland Sea sea–ice margin were not ΩAr≤1, the water column did exhibit the lowest ΩAr values observed in the Greenland and Barents Seas, and was likely to have approached ΩAr≤1 during the winter months. We demonstrate that L. helicina shells are only susceptible to dissolution where both the periostracum has been breached and the aragonite beneath the breach is exposed to waters of ΩAr≤1. Exposure of multiple layers of aragonite in areas of deep dissolution indicate that, as with many molluscs, L. helicina is able to patch up dissolution damage to the shell by secreting additional aragonite internally and maintain their shell. We conclude that, unless breached, the periostracum provides an effective shield for pteropod shells against dissolution in waters ΩAr≤1, and when dissolution does occur the animal has an effective means of self-repair. We suggest that future studies of pteropod shell condition are undertaken on specimens from which the periostracum has not been removed in preparation
Evidence of Zonal-Flow-Driven Limit-Cycle Oscillations during L-H Transition and at H-mode Pedestal of a New Small-ELM Regime in EAST
Turbulence and jet-driven zonal flows: Secondary circulation in rotating fluids due to asymmetric forcing
We report on experiments and modeling on a rotating confined liquid that is forced by circumferential jets coaxial with the rotation axis, wherein system-scale secondary flows are observed to emerge. The jets are evenly divided in number between inlets and outlets and have zero net mass transport. For low forcing strengths the sign of this flow depends on the sign of a sloped end cap, which simulates a planetary β plane. For increased forcing strengths the secondary flow direction is insensitive to the slope sign, and instead appears to be dominated by an asymmetry in the forcing mechanism, namely, the difference in radial divergence between the inlet and outlet jet profiles. This asymmetry yields a net radial velocity that is affected by the Coriolis force, inducing secondary zonal flow
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