Flow processes in overexpanded chemical rocket nozzles. Part 3: Methods for the aimed flow separation and side load reduction

Methods aimed at reduction of overexpansion and side load resulting from asymmetric flow separation for rocket nozzles with a high opening ratio are described. The methods employ additional measures for nozzles with a fixed opening ratio. The flow separation can be controlled by several types of nozzle inserts, the properties of which are discussed. Side loads and overexpansion can be reduced by adapting the shape of the nozzle and taking other additional measures for controlled separation of the boundary layer, such as trip wires

Flow processes in overexpanded chemical rocket nozzles. Part 1: Flow separation

An investigation was made of published nozzle flow separation data in order to determine the parameters which affect the separation conditions. A comparison of experimental data with empirical and theoretical separation prediction methods leads to the selection of suitable equations for the separation criterion. The results were used to predict flow separation of the main space shuttle engine

Status of flow separation prediction in liquid propellant rocket nozzles

Flow separation which plays an important role in the design of a rocket engine nozzle is discussed. For a given ambient pressure, the condition of no flow separation limits the area ratio and, therefore, the vacuum performance. Avoidance of performance loss due to area ratio limitation requires a correct prediction of the flow separation conditions. To provide a better understanding of the flow separation process, the principal behavior of flow separation in a supersonic overexpanded rocket nozzle is described. The hot firing separation tests from various sources are summarized, and the applicability and accuracy of the measurements are described. A comparison of the different data points allows an evaluation of the parameters that affect flow separation. The pertinent flow separation predicting methods, which are divided into theoretical and empirical correlations, are summarized and the numerical results are compared with the experimental points

Flow processes in overexpanded chemical rocket nozzles. Part 2: Side loads due to asymmetric separation

Methods for measuring the lateral forces, occurring as a result of asymmetric nozzle flow separation, are discussed. The effect of some parameters on the side load is explained. A new method was developed for calculation of the side load. The values calculated are compared with side load data of the J-2 engine. Results are used for predicting side loads of the space shuttle main engine

Emergency Medicine Palliative Care Access (EMPallA): Protocol for a multicentre randomised controlled trial comparing the effectiveness of specialty outpatient versus nurse-led telephonic palliative care of older adults with advanced illness

Introduction Emergency department (ED)-initiated palliative care has been shown to improve patient-centred outcomes in older adults with serious, life-limiting illnesses. However, the optimal modality for providing such interventions is unknown. This study aims to compare nurse-led telephonic case management to specialty outpatient palliative care for older adults with serious, life-limiting illness on: (1) quality of life in patients; (2) healthcare utilisation; (3) loneliness and symptom burden and (4) caregiver strain, caregiver quality of life and bereavement. Methods and analysis This is a protocol for a pragmatic, multicentre, parallel, two-arm randomised controlled trial in ED patients comparing two established models of palliative care: nurse-led telephonic case management and specialty, outpatient palliative care. We will enrol 1350 patients aged 50+ years and 675 of their caregivers across nine EDs. Eligible patients: (1) have advanced cancer (metastatic solid tumour) or end-stage organ failure (New York Heart Association class III or IV heart failure, end-stage renal disease with glomerular filtration rate /min/m2, or global initiative for chronic obstructive lung disease stage III, IV or oxygen-dependent chronic obstructive pulmonary disease); (2) speak English; (3) are scheduled for ED discharge or observation status; (4) reside locally; (5) have a working telephone and (6) are insured. Patients will be excluded if they: (1) have dementia; (2) have received hospice care or two or more palliative care visits in the last 6 months or (3) reside in a long-term care facility. We will use patient-level block randomisation, stratified by ED site and disease. Effectiveness will be compared by measuring the impact of each intervention on the specified outcomes. The primary outcome will measure change in patient quality of life. Ethics and dissemination Institutional Review Board approval was obtained at all study sites. Trial results will be submitted for publication in a peer-reviewed journal

Emergency Medicine Palliative Care Access (EMPallA): Preliminary Data from a Multi-Center Randomized Controlled Trial

Introduction: Emergency department (ED)-initiated palliative care has been shown to improve patient-centered outcomes in older adults with serious illnesses, but the optimal modality for providing such interventions is unknown. The EMPallA trial compares nurse-led, telephonic case management with specialty, outpatient palliative care on: 1) patient quality of life (QOL); 2) healthcare utilization; 3) loneliness and symptom burden; and 4) caregiver strain, QOL, and bereavement. Objective: Summarize preliminary demographic and QOL data for the EMPallA cohort. Methods: A pragmatic, parallel, two-arm randomized controlled trial is enrolling 1350 ED patients across 9 EDs over 3 years to compare the effectiveness of palliative care models. Eligible patients have end-stage heart failure, renal disease, chronic obstructive pulmonary disease (COPD), or cancer. Baseline data is collected at bedside using surveys. Functional Assessment of Cancer Therapy - General (FACT-G) QOL scores are rescaled into T-scores based on general US and cancer patient samples, standardized with mean 50 and standard deviation 10. Results: 138 patients enrolled from April 16 to October 16, 2018. Average age was 69 years; 55% were female, and 55% were white. Advanced cancer was most prevalent (48%), followed by heart failure (24%), COPD (23%), and end-stage renal disease (15%). Average FACT-G T-scores were 41 (general population) and 40 (cancer patients), which are below population means of 50 by more than 5, a clinically-meaningful difference. Discussion: This gender-balanced, racially-diverse cohort stands to benefit in QOL from palliative care. When trial enrollment and follow-up are complete, the impact of interventions can be assessed

Educating pharmacists on the risks of strong opioids with descriptive and simulated experience risk formats: A randomized controlled trial

Objectives. High opioid prescription rates in the United States and Europe suggest miscalibrated risk perceptions among those who prescribe, dispense, and take opioids. Findings from cognitive decision science suggest that risk perceptions and behaviors can differ depending on whether people learn about risks by experience or description. This study investigated effects of a descriptive versus an experience-based risk education format on pharmacists’ risk perceptions and counseling behavior in the long-term administration of strong opioids to patients with chronic noncancer pain. Methods. In an exploratory, randomized controlled online trial, 300 German pharmacists were randomly assigned to either a descriptive format (fact box) or a simulated experience format (interactive simulation). Primary Outcome Measures. 1) Objective risk perception, 2) subjective risk perception, and 3) intended and 4) actual counseling behavior. Results. Both risk formats significantly improved pharmacists’ objective risk perception, but pharmacists exposed to the fact box estimated the benefit-harm ratio more accurately than those exposed to the simulation. Both formats proved equally effective in adjusting pharmacists’ subjective risk perception toward a better recognition of opioids’ harms; however, pharmacists receiving the simulation showed a greater change in their actual counseling behavior and higher consistency between their intended and actual counseling than pharmacists receiving the fact box. Conclusion. The simulated experience format was less effective than the descriptive format in improving pharmacists’ objective risk perception, equally effective in motivating pharmacists to counsel patients on less risky treatment alternatives and more effective in changing the reported actual counseling behavior. Implications. These exploratory findings provide important insights into the relevance of the description-experience gap for drug safety and raise questions for future research regarding the specific mechanisms at work

Energy-Efficient Neuromorphic Architectures for Nuclear Radiation Detection Applications

A comprehensive analysis and simulation of two memristor-based neuromorphic architectures for nuclear radiation detection is presented. Both scalable architectures retrofit a locally competitive algorithm to solve overcomplete sparse approximation problems by harnessing memristor crossbar execution of vector–matrix multiplications. The proposed systems demonstrate excellent accuracy and throughput while consuming minimal energy for radionuclide detection. To ensure that the simulation results of our proposed hardware are realistic, the memristor parameters are chosen from our own fabricated memristor devices. Based on these results, we conclude that memristor-based computing is the preeminent technology for a radiation detection platform

The Questionnaire "SFDP26-German": a reliable tool for evaluation of clinical teaching?

Aims: Evaluation of the effectiveness of clinical teaching is an important contribution for the quality control of medical teaching. This should be evaluated using a reliable instrument in order to be able to both gauge the status quo and the effects of instruction. In the Stanford Faculty Development Program (SFDP), seven categories have proven to be appropriate