6,595 research outputs found
A comparison of two position estimate algorithms that use ILS localizer and DME information. Simulation and flight test results
Simulation and flight tests were conducted to compare the accuracy of two algorithms designed to compute a position estimate with an airborne navigation computer. Both algorithms used ILS localizer and DME radio signals to compute a position difference vector to be used as an input to the navigation computer position estimate filter. The results of these tests show that the position estimate accuracy and response to artificially induced errors are improved when the position estimate is computed by an algorithm that geometrically combines DME and ILS localizer information to form a single component of error rather than by an algorithm that produces two independent components of error, one from a DMD input and the other from the ILS localizer input
Surfaxe: Systematic surface calculations
Surface science is key to understanding the properties of a wide range of materials for energy applications, from catalysts to solar cells to battery components. Computational modelling based on quantum mechanics is often used to calculate surface properties of materials, which in turn determine their stability and performance. The maturity of these āfirst-principlesā methods, coupled with the huge amount of computational power accessible today, means they can now be used predictively in high-throughput screening workflows to suggest new materials for specific applications before they are synthesised. The surfaxe package provides a framework for such screening workflows, automating each stage of the process
Understanding Student Computational Thinking with Computational Modeling
Recently, the National Research Council's framework for next generation
science standards highlighted "computational thinking" as one of its
"fundamental practices". 9th Grade students taking a physics course that
employed the Modeling Instruction curriculum were taught to construct
computational models of physical systems. Student computational thinking was
assessed using a proctored programming assignment, written essay, and a series
of think-aloud interviews, where the students produced and discussed a
computational model of a baseball in motion via a high-level programming
environment (VPython). Roughly a third of the students in the study were
successful in completing the programming assignment. Student success on this
assessment was tied to how students synthesized their knowledge of physics and
computation. On the essay and interview assessments, students displayed unique
views of the relationship between force and motion; those who spoke of this
relationship in causal (rather than observational) terms tended to have more
success in the programming exercise.Comment: preprint to submit to PERC proceedings 201
Resistance to hydroxyurea in Aspergillus nidulans by gene mutation and by putative gene amplification.
Resistance to hydroxyurea in Aspergillus nidulans by gene mutation and by putative gene amplification
Recent La Plata basin drought conditions observed by satellite gravimetry
The Gravity Recovery and Climate Experiment (GRACE) provides quantitative
measures of terrestrial water storage (TWS) change. GRACE data show a
significant decrease in TWS in the lower (southern) La Plata river basin of
South America over the period 2002-2009, consistent with recognized drought
conditions in the region. GRACE data reveal a detailed picture of temporal and
spatial evolution of this severe drought event, which suggests that the drought
began in lower La Plata in around austral spring 2008 and then spread to the
entire La Plata basin and peaked in austral fall 2009. During the peak, GRACE
data show an average TWS deficit of ~12 cm (equivalent water layer thickness)
below the 7 year mean, in a broad region in lower La Plata. GRACE measurements
are consistent with accumulated precipitation data from satellite remote
sensing and with vegetation index changes derived from Terra satellite
observations. The Global Land Data Assimilation System model captures the
drought event but underestimates its intensity. Limited available
groundwater-level data in southern La Plata show significant groundwater
depletion, which is likely associated with the drought in this region.
GRAC-observed TWS change and precipitation anomalies in the studied region
appear to closely correlate with the ENSO climate index, with dry and wet
seasons corresponding to La Ni\~na and El Ni\~no events, respectively
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Factors influencing utilisation of āfree-standingā and āalongsideā midwifery units for low-risk births in England: a mixed-methods study
Background
Midwifery-led units (MUs) are recommended for ālow-riskā births by the National Institute for Health and Care Excellence but according to the National Audit Office were not available in one-quarter of trusts in England in 2013 and, when available, were used by only a minority of the low-risk women for whom they should be suitable. This study explores why.
Objectives
To map the provision of MUs in England and explore barriers to and facilitators of their development and use; and to ascertain stakeholder views of interventions to address these barriers and facilitators.
Design
Mixed methods ā first, MU access and utilisation across England was mapped; second, local media coverage of the closure of free-standing midwifery units (FMUs) were analysed; third, case studies were undertaken in six sites to explore the barriers and facilitators that have an impact on the development of MUs; and, fourth, by convening a stakeholder workshop, interventions to address the barriers and facilitators were discussed.
Setting
English NHS maternity services.
Participants
All trusts with maternity services.
Interventions
Establishing MUs.
Main outcome measures
Numbers and types of MUs and utilisation of MUs.
Results
Births in MUs across England have nearly tripled since 2011, to 15% of all births. However, this increase has occurred almost exclusively in alongside units, numbers of which have doubled. Births in FMUs have stayed the same and these units are more susceptible to closure. One-quarter of trusts in England have no MUs; in those that do, nearly all MUs are underutilised. The study findings indicate that most trust managers, senior midwifery managers and obstetricians do not regard their MU provision as being as important as their obstetric-led unit provision and therefore it does not get embedded as an equal and parallel component in the trustās overall maternity package of care. The analysis illuminates how provision and utilisation are influenced by a complex range of factors, including the medicalisation of childbirth, financial constraints and institutional norms protecting the status quo.
Limitations
When undertaking the case studies, we were unable to achieve representativeness across social class in the womenās focus groups and struggled to recruit finance directors for individual interviews. This may affect the transferability of our findings.
Conclusions
Although there has been an increase in the numbers and utilisation of MUs since 2011, significant obstacles remain to MUs reaching their full potential, especially FMUs. This includes the capacity and willingness of providers to address womenās information needs. If these remain unaddressed at commissioner and provider level, childbearing womenās access to MUs will continue to be restricted.
Future work
Work is needed on optimum approaches to improve decision-makersā understanding and use of clinical and economic evidence in service design. Increasing womenās access to information about MUs requires further studies of professionalsā understanding and communication of evidence. The role of FMUs in the context of rural populations needs further evaluation to take into account user and community impact.
Funding
This project was funded by the National Institute for Health Research (NIHR) Health Services and Delivery Research programme and will be published in full in Health Services and Delivery Research; Vol. 8, No. 12. See the NIHR Journals Library website for further project information
Aspects of the pathophysiology of blue crabs, Callinectes sapidus, infected with the parasitic dinoflagellate Hematodinium perezi
Blue crabs, Callinectes sapidus, infected with Hematodinium perezi frequently show signs of weakness and lethargy and die when stressed by handling or capture. Radical changes to the hemolymph of heavily infected crabs are obvious by reduced clotting ability, discoloration. and a 50% to 70% decline in total hemocyte density. Few other signs of infection are associated with infections and the resulting mortalities of blue crabs. To assay physiological changes in infected crabs, we measured serum proteins, hemocyanin, serum acid phosphatase, various hemolymph enzymes, hernagglutination activity, and tissue glycogen levels in relation to intensity of infection with H. perezi. Serum proteins and hemocyanin levels were lower in infected versus uninfected males, but not in infected versus uninfected females. Acid phosphatase activity was directly related to infection by the parasite. Acid phosphatase activity in the hemolymph was below the detection limit in uninfected crabs, but was detectably high in lightly, moderately and heavily infected crabs. Hemagglutination, possible indicator of innate Immoral defense activity, was not affected by infection. Glycogen levels in the hepatopancreas of infected crabs decreased by 50% in females and 70% in males compared to controls. Infection by H. perezi caused significant alterations to the hemolymph chemistry and metabolism of the crab. Changes in serum proteins, hemocyanin, and glycogen levels in heavy infections indicate that crabs probably die from metabolic exhaustion
Immorality and Irrationality
Does immorality necessarily involve irrationality? The question is often taken to be among the deepest in moral philosophy. But apparently deep questions sometimes admit of deflationary answers. In this case we can make way for a deflationary answer by appealing to dualism about rationality, according to which there are two fundamentally distinct notions of rationality: structural rationality and substantive rationality. I have defended dualism elsewhere. Here, Iāll argue that it allows us to embrace a sensible ā I will not say boring ā moderate view about the relationship between immorality and irrationality: roughly, that immorality involves substantive irrationality, but not structural irrationality. I defend this moderate view, and argue that many of the arguments for less moderate views turn either on missing the distinction between substantive and structural rationality, or on misconstruing it
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Factors influencing the utilisation of free-standing and alongside midwifery units in England: a qualitative research study
OBJECTIVE: To identify factors influencing the provision, utilisation and sustainability of midwifery units (MUs) in England.
DESIGN: Case studies, using individual interviews and focus groups, in six National Health Service (NHS) Trust maternity services in England.
SETTING AND PARTICIPANTS: NHS maternity services in different geographical areas of England Maternity care staff and service users from six NHS Trusts: two Trusts where more than 20% of all women gave birth in MUs, two Trusts where less than 10% of all women gave birth in MUs and two Trusts without MUs. Obstetric, midwifery and neonatal clinical leaders, managers, service user representatives and commissioners were individually interviewed (n=57). Twenty-six focus groups were undertaken with midwives (n=60) and service users (n=52).
MAIN OUTCOME MEASURES: Factors influencing MU use.
FINDINGS: The study findings identify several barriers to the uptake of MUs. Within a context of a history of obstetric-led provision and lack of decision-maker awareness of the clinical and economic evidence, most Trust managers and clinicians do not regard their MU provision as being as important as their obstetric unit (OU) provision. Therefore, it does not get embedded as an equal and parallel component in the Trust's overall maternity package of care. The analysis illuminates how implementation of complex interventions in health services is influenced by a range of factors including the medicalisation of childbirth, perceived financial constraints, adequate leadership and institutional norms protecting the status quo.
CONCLUSIONS: There are significant obstacles to MUs reaching their full potential, especially free-standing midwifery units. These include the lack of commitment by providers to embed MUs as an essential service provision alongside their OUs, an absence of leadership to drive through these changes and the capacity and willingness of providers to address women's information needs. If these remain unaddressed, childbearing women's access to MUs will continue to be restricted
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