668 research outputs found

    Wind-tunnel investigation of a flush airdata system at Mach numbers from 0.7 to 1.4

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    Flush pressure orifices installed on the nose section of a 1/7-scale model of the F-14 airplane were evaluated for use as a flush airdata system (FADS). Wing-tunnel tests were conducted in the 11- by 11-ft Unitary Wind Tunnel at NASA Ames Research Center. A full-scale FADS of the same configuration was previously tested using an F-14 aircraft at the Dryden Flight Research Facility of NASA Ames Research Center (Ames-Dryden). These tests, which were published, are part of a NASA program to assess accuracies of FADS for use on aircraft. The test program also provides data to validate algorithms for the shuttle entry airdata system developed at the NASA Langley Research Center. The wind-tunnel test Mach numbers were 0.73, 0.90, 1.05, 1.20, and 1.39. Angles of attack were varied in 2 deg increments from -4 deg to 20 deg. Sideslip angles were varied in 4 deg increments from -8 deg to 8 deg. Airdata parameters were evaluated for determination of free-stream values of stagnation pressure, static pressure, angle of attack, angle of sideslip, and Mach number. These parameters are, in most cases, the same as the parameters investigated in the flight test program. The basic FADS wind-tunnel data are presented in tabular form. A discussion of the more accurate parameters is included

    Procedural Decision Support Through The Use of PRODEMO

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    Procedural decisions, i.e., decisions involving the application of laws, regulations, prescriptions...constitute a tremendous amount of everyday decisions made in any kind of organizations. In this paper, decision tables are put forword as a basic technique enabling the user to structure and to check procedural decisions for completeness and correctness. It is shown that the use of the interactive PRODEMO (PROcedural DEcision MOdeling) system enhances the capabilities of the technique for modeling as well as for making procedural decisions

    Local Flow Conditions for Propulsion Experiments on the NASA F-15B Propulsion Flight Test Fixture

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    Local flow conditions were measured underneath the National Aeronautics and Space Administration F-15B airplane to support development of future experiments on the Propulsion Flight Test Fixture (PFTF). The local Mach number and flow angles were measured using a conventional air data boom on a cone-cylinder mounted under the PFTF and compared with the airplane air data nose boom measurements. At subsonic flight speeds, the airplane and PFTF Mach numbers were approximately equal. Transonic Mach number values were up to 0.1 greater at the PFTF than the airplane, which is a counterintuitive result. The PFTF local supersonic Mach numbers were as much as 0.46 less than the airplane values. The maximum local Mach number at the PFTF was approximately 1.6 at an airplane Mach number near 2.0. The PFTF local angle of attack was negative at all Mach numbers, ranging from -3 to -8 degrees. When the airplane angle of sideslip was zero, the PFTF local value was zero between Mach 0.8 and Mach 1.1, -2 degrees between Mach 1.1 and Mach 1.5, and increased from zero to 1 degree from Mach 1.5 to Mach 2.0. Airplane inlet shock waves crossed the aerodynamic interface plane between Mach 1.85 and Mach 1.90

    Perspectivas epistemológicas no estudo científico e a avaliação clínica das funções executivas

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    En este artículo se examinan perspectivas epistemológicas que han moldeado e influenciado la búsqueda científica orientada hacia comprender aquello que los neuropsicólogos denominan las "funciones ejecutivas (FE). El término funciones ejecutivas se refiere a aspectos de control de la cognición y la conducta. Las ideas expuestas en este manuscrito presuponen que la orientación epistemológica de una persona determina la manera en la que ella conceptualiza la interacción entre las funciones cerebrales y su entorno físico. Cada una de esas orientaciones conlleva suposiciones acerca del modo como operan las FE y, por ende, el modo como deben ser evaluadas. Hasta fechas recientes esto se había abordado principalmente desde el punto de vista de dos perspectivas teóricas. Una de ellas, la analítica, tiene sus raíces en el movimiento positivista. La otra, también conocida como "ciencia romántica" es sintética, y provee las bases del trabajo científico del muy celebrado neuropsicólogo ruso A.R. Luria. Una tercera perspectiva, formulada en el marco de la "cognición corpórea", ha sido propuesta en los últimos 20 años, y está más estrechamente asociada con los trabajos de Francisco Varela. Se examina aquí, por medio de una revisión reflexiva e integradora de la literatura pertinente, la manera como esas tres perspectivas epistemológicas han influido sobre la investigación y la práctica clínica de la neuropsicología.In this article, epistemological perspectives that have shaped and affected the scientific quest for understanding what neuropsychologists term "executive functions" are reviewed. Executive functions refer to the control functions of cognition and behavior. The underlying thesis of the paper is that one's epistemological orientation determines how one sees the interaction between brain functions and our status in the world. Each different orientation thus carries with it implications with regard to how executive functions operate, as well as how, therefore, one should try to assess them. Until recently, these functions were approached through two primary epistemological points of view. One is analytic, which has its roots in the positivistic movement. The other approach is synthetic, otherwise known as "romantic science", and forms the basis of the work of the prominent Russian neuropsychologist A.R. Luria. A third epistemological perspective, articulated under the umbrella of 'embodied cognition' approaches, has been advanced in the last 20 years, and is associated most closely with the work of Francisco Varela. A review of, and reflection on how these perspectives have affected research and clinical practice in neuropsychology is provided.Neste artigo examinam-se as perspectivas epistemológicas que moldaram e influenciaram a busca científica orientada à compreender aquilo que os neuropsicólogos denominam as "funções executivas (FE). O termo funções executivas se refere a aspectos de controle da cognição e a conduta. As ideias expostas neste manuscrito pressupõem que a orientação epistemológica de uma pessoa determina a maneira em que ela conceitualiza a interação entre as funções cerebrais e seu entorno físico. Cada uma dessas orientações leva a suposições sobre o modo como operam as FE e, portanto, o modo como devem ser avaliadas. Até datas recentes isto havia sido abordado principalmente desde o ponto de vista de duas perspectivas teóricas. Uma delas, a analítica, tem suas raízes no movimento positivista. A outra, também conhecida como "ciência romântica" é sintética, e fornece as bases do trabalho científico do muito celebrado neuropsicólogo russo A.R. Luria. Uma terceira perspectiva, formulada no marco da "cognição corpórea", foi proposta nos últimos 20 anos, e está mais estreitamente associada com os trabalhos de Francisco Varela. Examina-se aqui, através de uma revisão reflexiva e integradora da literatura pertinente, a maneira como essas três perspectivas epistemológicas influíram sobre a pesquisa e a prática da neuropsicologia

    Preliminary results from a subsonic high angle-of-attack flush airdata sensing (HI-FADS) system: Design, calibration, and flight test evaluation

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    A nonintrusive high angle-of-attack flush airdata sensing (HI-FADS) system was installed and flight-tested on the F-18 high alpha research flight vehicle. The system is a matrix of 25 pressure orifices in concentric circles on the nose of the vehicle. The orifices determine angles of attack and sideslip, Mach number, and pressure altitude. Pressure was transmitted from the orifices to an electronically scanned pressure module by lines of pneumatic tubing. The HI-FADS system was calibrated and demonstrated using dutch roll flight maneuvers covering large Mach, angle-of-attack, and sideslip ranges. Reference airdata for system calibration were generated by a minimum variance estimation technique blending measurements from two wingtip airdata booms with inertial velocities, aircraft angular rates and attitudes, precision radar tracking, and meteorological analyses. The pressure orifice calibration was based on identifying empirical adjustments to modified Newtonian flow on a hemisphere. Calibration results are presented. Flight test results used all 25 orifices or used a subset of 9 orifices. Under moderate maneuvering conditions, the HI-FADS system gave excellent results over the entire subsonic Mach number range up to 55 deg angle of attack. The internal pneumatic frequency response of the system is accurate to beyond 10 Hz. Aerodynamic lags in the aircraft flow field caused some performance degradation during heavy maneuvering

    Distribution and Excretion of TEGDMA in Guinea Pigs and Mice

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    The monomer triethyleneglycoldimethacrylate (TEGDMA) is used as a diluent in many resin-based dental materials. It was previously shown in vitro that TEGDMA was released into the adjacent biophase from such materials during the first days after placement. In this study, the uptake, distribution, and excretion of 14C-TEGDMA applied via gastric, intradermal, and intravenous administration at dose levels well above those encountered in dental care were examined in vivo in guinea pigs and mice as a test of the hypothesis that TEGDMA reaches cytotoxic levels in mammalian tissues. 14C-TEGDMA was taken up rapidly from the stomach and small intestine after gastric administration in both species and was widely distributed in the body following administration by each route. Most 14C was excreted within one day as 14 CO2. The peak equivalent TEGDMA levels in all mouse and guinea pig tissues examined were at least 1000-fold less than known toxic levels. The study therefore did not support the hypothesis

    Pharmacokinetic profile of irinotecan in patients with chronic kidney disease:Two cases and literature review

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    Aims: There are limited pharmacokinetic data on the use of irinotecan in patients with reduced glomerular filtration rate (GFR) and no haemodialysis. In this case report, we present 2 cases and review the current literature. Methods: The dose of irinotecan in both patients was reduced pre-emptively due to reduced GFR. The first patient had her irinotecan dose reduced to 50%, but was nevertheless admitted to hospital because of irinotecan-induced toxicity, including gastrointestinal toxicity and neutropenic fever. The dose was reduced further to 40% for the second cycle; however, the patient was again admitted to the hospital, and irinotecan was stopped indefinitely. The second patient also had his irinotecan dose reduced to 50% and was admitted to the emergency department for gastrointestinal toxicity after the first cycle. However, irinotecan could be administered in the same dose in later cycles. Results: The area under the curve to infinity of irinotecan and SN-38 in the first patient were comparable to those of an individual receiving 100% dose intensity. The area under the curve to infinity of irinotecan and SN-38 in patient 2 in both cycles were slightly less than reference values. Furthermore, clearance values of irinotecan and SN-38 in our patients were comparable to those without renal impairment. Conclusion: Our case report suggests that reduced GFR may not significantly affect the clearance of irinotecan and SN-38, but can still result in clinical toxicity. Reduced initial dosing seems indicated in this patient population. Further research is needed to fully understand the relationship between reduced GFR, pharmacokinetics, and toxicity of irinotecan and SN-38.</p

    Predictors of Time to Discontinuation of Levodopa-Carbidopa Intestinal Gel Infusion:A Retrospective Cohort Study

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    Background: Continuous intra-duodenal infusion of levodopa-carbidopa intestinal gel (LCIG) is a well-established therapy for patients with advanced Parkinson's disease (PD) suffering from motor complications despite optimized treatment with oral dopaminomimetics. However, time to discontinuation of treatment with LCIG varies considerably between patients, ranging from a few months to more than ten years. To improve the selection of candidates for LCIG, knowledge of prognostic factors is of paramount importance. Objective: To explore baseline predictors of time to discontinuation of LCIG. Methods: In this two-center retrospective cohort study, we reviewed the medical files of 98 PD patients treated with LCIG between April 2006 and December 2015 (53% male; mean age: 66.2 years; mean disease duration: 12.3 years). Baseline patient characteristics were used as covariates in Cox regression models. Results: During follow-up (mean observation time: 2.6 years; range: 0.1-9.3) eighteen patients discontinued treatment (18.4%), while seven patients died (7.1%). Median duration of treatment with LCIG, estimated with Kaplan-Meier analysis, was 7.8 years (95% CI: 6.7-9.0). Disease duration (in years) at baseline was a statistically significant predictor of time to discontinuation of LCIG (HR: 0.85; 95% CI: 0.75-0.96, p = 0.006). All other characteristics studied, e.g. age >70 years, did not show statistically significant associations with the total duration of treatment with LCIG. Conclusion: Our findings show a low overall rate of discontinuation of LCIG infusion, with a median duration of treatment of 7.8 years. Shorter disease duration at baseline appeared to be a predictor of earlier discontinuation of LCIG

    Once-weekly semaglutide for patients with type 2 diabetes:a cost-effectiveness analysis in the Netherlands

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    Objective Choosing therapies for type 2 diabetes that are both effective and cost-effective is vital as healthcare systems worldwide aim to maximize health of the population. The present analysis assessed the cost-effectiveness of once-weekly semaglutide (a novel glucagon-like peptide-1 (GLP-1) receptor agonist) versus insulin glargine U100 (the most commonly used basal insulin) and versus dulaglutide (an alternative once-weekly GLP-1 receptor agonist), from a societal perspective in the Netherlands. Research design and methods The IQVIA CORE Diabetes Model was used to project outcomes for once-weekly semaglutide 0.5 mg and 1 mg versus insulin glargine U100, once-weekly semaglutide 0.5 mg versus dulaglutide 0.75 mg, and once-weekly semaglutide 1 mg versus dulaglutide 1.5 mg. Clinical data were taken from the SUSTAIN 4 and SUSTAIN 7 clinical trials. The analysis captured direct and indirect costs, mortality, and the impact of diabetes-related complications on quality of life. Results Projections of outcomes suggested that once-weekly semaglutide 0.5 mg was associated with improved quality-adjusted life expectancy by 0.19 quality-adjusted life years (QALYs) versus insulin glargine U100 and 0.07 QALYs versus dulaglutide 0.75 mg. Once-weekly semaglutide 1 mg was associated with mean increases in quality-adjusted life expectancy of 0.27 QALYs versus insulin glargine U100 and 0.13 QALYs versus dulaglutide 1.5 mg. Improvements came at an increased cost versus insulin glargine U100, with incremental cost-effectiveness ratios from a societal perspective of _4988 and _495 per QALY gained for once-weekly semaglutide 0.5 mg and 1 mg, respectively, falling below Netherlands-specific willingness-to-pay thresholds. Improvements versus dulaglutide came at a reduced cost from a societal perspective for both doses of once-weekly semaglutide. Conclusions Once-weekly semaglutide is cost-effective versus insulin glargine U100, and dominant versus dulaglutide 0.75 and 1.5 mg for the treatment of type 2 diabetes, and represents a good use of healthcare resources in the Netherlands

    Population pharmacokinetics of treosulfan in paediatric patients undergoing hematopoietic stem cell transplantation

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    Aims: Treosulfan is an alkylating agent increasingly used prior to haematopoietic stem cell transplantation. The aim of this study was to develop a population pharmacokinetic (PK) model of treosulfan in paediatric haematopoietic stem cell transplantation recipients and to explore the effect of potential covariates on treosulfan PK. Also, a limited sampling model (LSM) will be developed to accurately predict treosulfan exposure suitable for a therapeutic drug monitoring setting. Methods: In this multicentre study, 91 patients, receiving a total dose of 30, 36 or 42&nbsp;g/m2 treosulfan, administered over 3 consecutive days, were enrolled. A population PK model was developed and demographic factors, as well as laboratory parameters, were included as potential covariates. In addition, a LSM was developed using data from 28 patients. Results: A 2-compartment model with first order elimination best described the data. Bodyweight with allometric scaling and maturation function were identified as significant predictors of treosulfan clearance. Treosulfan clearance reaches 90% of adult values at 4 postnatal years. A model-based dosing table is presented to target an exposure of 1650&nbsp;mg*h/L (population median) for different weight and age groups. Samples taken at 1.5, 4 and 7&nbsp;hours after start of infusion resulted in the best limited sampling strategy. Conclusions: This study provides a treosulfan population PK model in children and captures the developmental changes in clearance. A 3-point LSM allows for accurate and precise estimation of treosulfan exposure
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