4,205 research outputs found
Climb-dash real-time calculations
On-board rear-optimal climb-dash energy management, optimal symmetric flight with an intermediate vehicle model, and energy states are presented
Whale by-products for pig feeding
Pig feeding experiments at Denmark Research Station and Muresk Agricultural College in 1951 and 1952, were designed to investigate the value of whalemeal and whale solubles in comparison with meatmeal as protein supplements to a crushed wheat ration. Large quantities of whale solubles are available and, used efficiently, could greatly reduce the present shortage of protein supplements
Optimal symmetric flight studies
Several topics in optimal symmetric flight of airbreathing vehicles are examined. In one study, an approximation scheme designed for onboard real-time energy management of climb-dash is developed and calculations for a high-performance aircraft presented. In another, a vehicle model intermediate in complexity between energy and point-mass models is explored and some quirks in optimal flight characteristics peculiar to the model uncovered. In yet another study, energy-modelling procedures are re-examined with a view to stretching the range of validity of zeroth-order approximation by special choice of state variables. In a final study, time-fuel tradeoffs in cruise-dash are examined for the consequences of nonconvexities appearing in the classical steady cruise-dash model. Two appendices provide retrospective looks at two early publications on energy modelling and related optimal control theory
Elevated cerebral spinal fluid biomarkers in children with mucopolysaccharidosis I-H.
Mucopolysaccharidosis (MPS) type-IH is a lysosomal storage disease that results from mutations in the IDUA gene causing the accumulation of glycosaminoglycans (GAGs). Historically, children with the severe phenotype, MPS-IH (Hurler syndrome) develop progressive neurodegeneration with death in the first decade due to cardio-pulmonary complications. New data suggest that inflammation may play a role in MPS pathophysiology. To date there is almost no information on the pathophysiologic changes within the cerebral spinal fluid (CSF) of these patients. We evaluated the CSF of 25 consecutive patients with MPS-IH. While CSF glucose and total protein were within the normal range, we found a significantly mean elevated CSF opening pressure at 24 cm H2O (range 14-37 cm H2O). We observed a 3-fold elevation in CSF heparan sulfate and a 3-8 fold increase in MPS-IH specific non-reducing ends, I0S0 and I0S6. Cytokine analyses in CSF of children with MPS-IH showed significantly elevated inflammatory markers including: MCP-1 SDF-1a, IL-Ra, MIP-1b, IL-8, and VEGF in comparison to unaffected children. This is the largest report of CSF characteristics in children with MPS-IH. Identification of key biomarkers may provide further insight into the inflammatory-mediated mechanisms related to MPS diseases and perhaps lead to improved targeted therapies
Enhanced hydrogen storage in Ni/Ce composite oxides
The properties of dried (but not calcined) coprecipitated nickel ceria systems have been investigated in terms of their hydrogen emission characteristics following activation in hydrogen. XRD and BET data obtained on the powders show similarities to calcined ceria but it is likely that the majority of the material produced by the coprecipitation process is largely of an amorphous nature. XPS data indicate very little nickel is present on the outermost surface of the particles. Nevertheless, the thermal analytical techniques (TGA, DSC and TPD-MS) indicate that the hydrogen has access to the catalyst present and the nickel is able to generate hydrogen species capable of interacting with the support. Both unactivated and activated materials show two hydrogen emission features, viz. low temperature and high temperature emissions (LTE and HTE, respectively) over the temperature range 50 and 500 °C. A clear effect of hydrogen interaction with the material is that the activated sample not only emits much more hydrogen than the corresponding unactivated one but also at lower temperatures. H2 dissociation occurs on the reduced catalyst surface and the spillover mechanism transfers this active hydrogen into the ceria, possibly via the formation and migration of OH− species. The amount of hydrogen obtained (0.24 wt%) is 10× higher than those observed for calcined materials and would suggest that the amorphous phase plays a critical role in this process. The affiliated emissions of CO and CO2 with that of the HTE hydrogen (and consumption of water) strongly suggests a proportion of the hydrogen emission at this point arises from the water gas shift type reaction. It has not been possible from the present data to delineate between the various hydrogen storage mechanisms reported for ceria
Overview of the Langley subsonic research effort on SCR configuration
Recent advances achieved in the subsonic aerodynamics of low aspect ratio, highly swept wing designs are summarized. The most significant of these advances was the development of leading edge deflection concepts which effectively reduce leading edge flow separation. The improved flow attachment results in substantial improvements in low speed performance, significant delay of longitudinal pitch up, increased trailing edge flap effectiveness, and increased lateral control capability. Various additional theoretical and/or experimental studies are considered which, in conjunction with the leading edge deflection studies, form the basis for future subsonic research effort
Bi-partite entanglement entropy in integrable models with backscattering
In this paper we generalise the main result of a recent work by J. L. Cardy
and the present authors concerning the bi-partite entanglement entropy between
a connected region and its complement. There the expression of the leading
order correction to saturation in the large distance regime was obtained for
integrable quantum field theories possessing diagonal scattering matrices. It
was observed to depend only on the mass spectrum of the model and not on the
specific structure of the diagonal scattering matrix. Here we extend that
result to integrable models with backscattering (i.e. with non-diagonal
scattering matrices). We use again the replica method, which connects the
entanglement entropy to partition functions on Riemann surfaces with two branch
points. Our main conclusion is that the mentioned infrared correction takes
exactly the same form for theories with and without backscattering. In order to
give further support to this result, we provide a detailed analysis in the
sine-Gordon model in the coupling regime in which no bound states (breathers)
occur. As a consequence, we obtain the leading correction to the sine-Gordon
partition function on a Riemann surface in the large distance regime.
Observations are made concerning the limit of large number of sheets.Comment: 22 pages, 2 figure
Urologic surgery and COVID-19: How the pandemic is changing the way we operate
The coronavirus disease 2019 (COVID-19) pandemic has had a global impact on all aspects of healthcare, including surgical procedures. For urologists, it has affected and will continue to influence how we approach the care of patients pre-operatively, intra-operatively, and post-operatively. A risk-benefit assessment of each patient undergoing surgery should be performed during the COVID-19 pandemic based on the urgency of the surgery and the risk of viral illness and transmission. Patients with advanced age and comorbidities have a higher incidence of mortality. Routine preoperative testing and symptom screening is recommended to identify those with COVID-19. Adequate personal protective equipment (PPE) for the surgical team is essential to protect healthcare workers and ensure an adequate workforce. For COVID-19 positive or suspected patients, the use of N95 respirators is recommended if available. The anesthesia method chosen should attempt to minimize aerosolization of the virus. Negative pressure rooms are strongly preferred for intubation/extubation and other aerosolizing procedures. Although transmission has not yet been shown during laparoscopic and robotic procedures, efforts should be made to minimize the risk of aerosolization. Ultra low particulate air filters are recommended for use during minimally invasive procedures to decrease the risk of viral transmission. Thorough cleaning and sterilization should be performed post-operatively with adequate time allowed for the operating room air to be cycled after procedures. COVID-19 patients should be separated from non-infected patients at all levels of care including recovery to decrease the risk of infection. Future directions will be guided by outcomes and infection rates as social distancing guidelines are relaxed and more surgical procedures are reintroduced. Recommendations should be adapted to the local environment and will continue to evolve as more data becomes available, the shortage of testing and PPE is resolved, and a vaccine and therapeutics for COVID-19 are developed
Familial deficiency of vitamin K-dependent clotting factors: VITAMIN K-DEPENDENT CLOTTING FACTORS
Combined deficiency of vitamin K–dependent clotting factors II, VII, IX, and X (and proteins C, S, and Z) is usually an acquired clinical problem, often resulting from liver disease, malabsorption, or warfarin overdose. A rare inherited form of defective γ-carboxylation resulting in early onset of bleeding was first described by McMillan and Roberts in 1966 and subsequently has been termed vitamin K–dependent clotting factor deficiency (VKCFD). Biochemical and molecular studies identify 2 variants of this autosomal recessive disorder: VKCFD1, which is associated with point mutations in the γ-glutamylcarboxylase gene (GGCX), and VKCFD2, which results from point mutations in the vitamin K epoxide reductase gene (VKOR). Bleeding ranges in severity from mild to severe. Therapy includes high oral doses of vitamin K for prophylaxis, usually resulting in partial correction of factor deficiency, and episodic use of plasma infusions. Recent molecular studies have the potential to further our understanding of vitamin K metabolism, γ-carboxylation, and the functional role this posttranslational modification has for other proteins. The results may also provide potential targets for molecular therapeutics and pharmacogenetics
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