Research requirements for development of regenerative engines for helicopters

The improved specific fuel consumption of the regenerative engine was compared to a simple-cycle turboshaft engine. The performance improvement and fuel saving are obtained at the expense of increased engine weight, development and production costs, and maintenance costs. Costs and schedules are estimated for the elements of the research and development program. Interaction of the regenerative engine with other technology goals for an advanced civil helicopter is examined, including its impact on engine noise, hover and cruise performance, helicopter empty weight, drive-system efficiency and weight, one-engine-inoperative hover capability, and maintenance and reliability

Risk factors for failure of outpatient parenteral antibiotic therapy (OPAT) in infective endocarditis

Objectives: To identify risk factors for failure of outpatient antibiotic therapy (OPAT) in infective endocarditis (IE). Patients and methods: We identified IE cases managed at a single centre over 12 years from a prospectively maintained database. ‘OPAT failure’ was defined as unplanned readmission or antibiotic switch due to adverse drug reaction or antibiotic resistance. We analysed patient and disease-related risk factors for OPAT failure by univariate and multivariate logistic regression. We also retrospectively collected follow-up data on adverse disease outcome (defined as IE-related death or relapse) and performed Kaplan–Meier survival analysis up to 36 months following OPAT. Results: We identified 80 episodes of OPAT in IE. Failure occurred in 25/80 episodes (31.3%). On multivariate analysis, cardiac or renal failure [pooled OR 7.39 (95% CI 1.84–29.66), P = 0.005] and teicoplanin therapy [OR 8.69 (95% CI 2.01–37.47), P = 0.004] were independently associated with increased OPAT failure. OPAT failure with teicoplanin occurred despite therapeutic plasma levels. OPAT failure predicted adverse disease outcome up to 36 months (P = 0.016 log-rank test). Conclusions: These data caution against selecting patients with endocarditis for OPAT in the presence of cardiac or renal failure and suggest teicoplanin therapy may be associated with suboptimal OPAT outcomes. Alternative regimens to teicoplanin in the OPAT setting should be further investigated

Transverse Permeability of OSB. Part II. Modeling the Effects of Density and Core Fines Content

In this work a simple rule of mixtures model to characterize the permeability of an OSB composite as a function of fines contents and density is presented. Strands and fines in the core of the board are considered to lie between two extremes, either stacked in a series configuration (series model) or side by side in a parallel configuration (parallel model), with the permeability of the composite, Ksystem, being a function of relative permeabilities of the series and parallel models. Equations for the permeability of these two configurations, Kparallel and Kseries, are developed as functions of the known permeability of 100% strands, Ks, and 100% fines, Kf, and the mass fraction of fines, Mf. Data on the permeability of the core of OSB compressed to three density classes and made with 0 and 100% fines content are used to determine the permeability of the parallel and series models, respectively. The series coefficient, α, which represents the contribution from the series model, is determined using least squares fits to the permeability data for different target densities and 25%, 50%, and 75% fines contents. α was fairly consistent, ranging from 0.47 to 0.49 for these fines contents. Kparallel increases linearly with increasing fines content and Kseries increases exponentially, in accord with the actual data. The data for the low and medium target density boards were well described by the Ksystem predictions, whereas the model underestimates the permeability of boards containing 75% or 100% fines and compressed to high target density. The model was most sensitive to changes in Mf, Kf, and Ks, with other parameters, α and density ratio (ρs/ρf), having smaller effects. The proposed model is general and could be applied to other composites of mixed particle sizes such as particleboard

Permeability of OSB. Part I. The Effects of Core Fines Content and Mat Density on Transverse Permeability

This paper reports on the effects of density and core fines content on the transverse permeability, K, of oriented strandboard (OSB), with the aim of using fines generated during the log stranding process to improve mat permeability and possibly press efficiency. Forty-five OSB panels were made in the laboratory containing five levels of fines content (0, 25, 50, 75, and 100%) and compressed to three target density levels (low—450, medium—550, and high—650 kg/m3). Both density and fines content and their interaction significantly influenced Kcore, which increased exponentially with fines content at each density level. Above 75% fines, density level no longer had any significant effect on Kcore, indicating that as the mat is compressed, the presence of fines maintains a more interconnected void system through which gas can pass. The rate of heat transfer to the core was affected by board thickness but contrary to expectations, not by fines content. Fines content did, however, affect the accumulation of gas pressure in the high target density heavily compressed boards; maximum core gas pressure was significantly reduced if core fines content was greater than 50%

Neighborhoods of trees in circular orderings

In phylogenetics, a common strategy used to construct an evolutionary tree for a set of species X is to search in the space of all such trees for one that optimizes some given score function (such as the minimum evolution, parsimony or likelihood score). As this can be computationally intensive, it was recently proposed to restrict such searches to the set of all those trees that are compatible with some circular ordering of the set X. To inform the design of efficient algorithms to perform such searches, it is therefore of interest to find bounds for the number of trees compatible with a fixed ordering in the neighborhood of a tree that is determined by certain tree operations commonly used to search for trees: the nearest neighbor interchange (nni), the subtree prune and regraft (spr) and the tree bisection and reconnection (tbr) operations. We show that the size of such a neighborhood of a binary tree associated with the nni operation is independent of the tree’s topology, but that this is not the case for the spr and tbr operations. We also give tight upper and lower bounds for the size of the neighborhood of a binary tree for the spr and tbr operations and characterize those trees for which these bounds are attained

Image based simulation of one-dimensional compression tests on carbonate sand

High factors of safety and conservative methods are commonly used on foundation design on shelly carbonate soils. A better understanding of the behavior of this material is, thus, critical for more sustainable approaches for the design of a number of offshore structures and submarine pipelines. In particular, understanding the physical phenomena taking place at the microscale has the potential to spur the development of robust computational methods. In this study, a one-dimensional compression test was performed inside an X-ray scanner to obtain 3D images of the evolving internal structure of a shelly carbonate sand. A preliminary inspection of the images through five loading increments has shown that the grains rearrange under loading and in some cases cracks develop at the contacts. In order to replicate of the experiments in the numerical domain, the 3D image of the soil prior to loading was imported into a micro Finite Element (µFE) framework. This image-based modelling tool enables measurements of the contact force and stress map inside the grains while making use of the real microstructure of the soil. The potential of the µFE model to contribute insights into yield initiation within the grain is demonstrated here. This is of particular interest to better understand the breakage of shelly grains underpinning their highly compressive behavior

Emergence of hyperons in failed supernovae: trigger of the black hole formation

We investigate the emergence of strange baryons in the dynamical collapse of a non-rotating massive star to a black hole by the neutrino-radiation hydrodynamical simulations in general relativity. By following the dynamical formation and collapse of nascent proto-neutron star from the gravitational collapse of a 40Msun star adopting a new hyperonic EOS table, we show that the hyperons do not appear at the core bounce but populate quickly at ~0.5-0.7 s after the bounce to trigger the re-collapse to a black hole. They start to show up off center owing to high temperatures and later prevail at center when the central density becomes high enough. The neutrino emission from the accreting proto-neutron star with the hyperonic EOS stops much earlier than the corresponding case with a nucleonic EOS while the average energies and luminosities are quite similar between them. These features of neutrino signal are a potential probe of the emergence of new degrees of freedom inside the black hole forming collapse.Comment: 11 pages, 3 figures, accepted for publication in ApJ

Geometric Interpretation of the Mixed Invariants of the Riemann Spinor

Mixed invariants are used to classify the Riemann spinor in the case of Einstein-Maxwell fields and perfect fluids. In the Einstein-Maxwell case these mixed invariants provide information as to the relative orientation of the gravitational and electromagnetic principal null directions. Consideration of the perfect fluid case leads to some results about the behaviour of the Bel-Robinson tensor regarded as a quartic form on unit timelike vectors.Comment: 31 pages, AMS-LaTe

The care and support needs of residential care home residents with comorbid cancer and dementia: A qualitative review and ethnographic study.

Background: Prevalence of cancer and dementia are strongly related to age. In the UK, 70% of care home residents have dementia. By 2040, older people (aged 65+) will account for 77% of all people living with cancer. Residents with only one of these conditions may have complex care needs. Having comorbid cancer and dementia (CCD) is likely to bring further challenges. This is the first research project to examine the care and support needs of people with CCD living in residential care homes and areas for improvement. Aims: To explore: (1) The care and support needs of people with CCD living in residential care homes. (2) What constitutes good care for people with CCD, their family/supporters, and residential care home staff. (3) Potential barriers and facilitators to providing good care for people with CCD. Methods: (1) Literature review to examine implications for cancerrelated care for people with dementia living in residential care homes. (2) Interviews with 5‐10 men and women with CCD, their family members/ supporters, and residential care home staff. (3) Ethnographic observations of 5‐10 people with CCD to further explore barriers and facilitators to good care. Results: Emergent findings from the literature review will be presented, and their implications for supporting people with CCD living in residential care homes discussed. Conclusions: Findings from this study will help improve the care and support of people with CCD and will contribute to a wider programme of research exploring the cancer care needs of people with dementia across a variety of care settings

Biomass fuel use and indoor air pollution in homes in Malawi

Background: Air pollution from biomass fuels in Africa is a significant cause of mortality and morbidity both in adults and children. The work describes the nature and quantity of smoke exposure from biomass fuel in Malawian homes. Methods: Markers of indoor air quality were measured in 62 homes (31 rural and 31 urban) over a typical 24 h period. Four different devices were used (one gravimetric device, two photometric devices and a carbon monoxide (HOBO) monitor. Gravimetric samples were analysed for transition metal content. Data on cooking and lighting fuel type together with information on indicators of socioeconomic status were collected by questionnaire. Results: Respirable dust levels in both the urban and rural environment were high with the mean (SD) 24 h average levels being 226 μg/m3 (206 μg/m3). Data from real-time instruments indicated respirable dust concentrations were >250 μg/m3 for >1 h per day in 52% of rural homes and 17% of urban homes. Average carbon monoxide levels were significantly higher in urban compared with rural homes (6.14 ppm vs 1.87 ppm; p<0.001). The transition metal content of the smoke was low, with no significant difference found between urban and rural homes. Conclusions: Indoor air pollution levels in Malawian homes are high. Further investigation is justified because the levels that we have demonstrated are hazardous and are likely to be damaging to health. Interventions should be sought to reduce exposure to concentrations less harmful to health