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Steady-State Low-Order Explicit (LOE) Runge-Kutta Schemes with Improved ConvergenceSabri, Zaid January 2020 (has links)
No description available.
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ARIA-E vid behandling av Alzheimers sjukdom med monoklonala antikroppar / ARIA-E frekvens in treatment with monoclonal antibodies in patients with Alzheimers diseaseHall, Anna January 2023 (has links)
Introduction: Alzheimer's disease is a neurodegenerative disease that initially manifests itself primarily as impaired short-term memory and impaired language ability. The course of the disease is mainly due to an atrophy in the brain that can be attributed to the protein amyloid B and tau. Monoclonal antibodies that target Alzheimer's disease often have a high rate of cerebral edema, where proteinaceous fluid leaks into the extracellular space of the brain and creates edema. Some of the most common symptoms for amyloid-related imaging abnormalities (ARIA-E) are headache, dizziness, and blurred vision. In a few cases, patients with ARIA-E need to be hospitalized for observation, but most show a decline in ARIA-E within one to two months. Objective: To investigate the frequency of ARIA-E in clinical studies of monoclonal antibodies to patients with Alzhiemer's disease and to investigate the role of the ApoE4 allele in the development of ARIA-E. Method: Literature review of five RCT studies based on four different monoclonal antibodies. PubMed was used to search for the RCT-studies. Results: ARIA-E varies between different types of antibodies. ARIA-E usually occurs early in treatment when the degree of amyloid b is highest in the brain. Most cases are asymptomatic and treatment resumes within 1-2 months. Conclusion: Aria-E frequency correlates strongly with dose strength as well as APOE4 -status and most of the incidences are asymptomatic. With the right titration and individually selected drugs as well as individual dosages a safe care can be established for patients with Alzheimer's disease. If treatment is initiated at an early stage, the risk of side effects is reduced and more neurons can be saved from atrophy. The combination of several different types of medicine will further reduce the risk of ARIA-E.
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Effect of drinking water disinfection by-products in human peripheral blood lymphocytes and spermAli, Aftab H.M., Kurzawa-Zegota, Malgorzata, Najafzadeh, Mojgan, Gopalan, Rajendran C., Plewa, M.J., Anderson, Diana 26 August 2014 (has links)
No / Drinking water disinfection by-products (DBPs) are generated by the chemical disinfection of water and may pose hazards to public health. Two major classes of DBPs are found in finished drinking water: haloacetic acids (HAAs) and trihalomethanes (THMs). HAAs are formed following disinfection with chlorine, which reacts with iodide and bromide in the water. Previously the HAAs were shown to be cytotoxic, genotoxic, mutagenic, teratogenic and carcinogenic. OBJECTIVES: To determine the effect of HAAs in human somatic and germ cells and whether oxidative stress is involved in genotoxic action. In the present study both somatic and germ cells have been examined as peripheral blood lymphocytes and sperm. The effects of three HAA compounds: iodoacetic acid (IAA), bromoacetic acid (BAA) and chloroacetic acid (CAA) were investigated. After determining appropriate concentration responses, oxygen radical involvement with the antioxidants, butylated hydroxanisole (BHA) and the enzyme catalase, were investigated in the single cell gel electrophoresis (Comet) assay under alkaline conditions, >pH 13 and the micronucleus assay. In the Comet assay, BHA and catalase were able to reduce DNA damage in each cell type compared to HAA alone. In the micronucleus assay, micronuclei (MNi) were found in peripheral lymphocytes exposed to all three HAAs and catalase and BHA were in general, able to reduce MNi induction, suggesting oxygen radicals play a role in both assays. These observations are of concern to public health since both human somatic and germ cells show similar genotoxic responses.
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Advancements in CFD-CAA Method: Noise Source Identification, Anti-Aliasing Filter, Time-Domain Impedance Boundary Condition, and ApplicationsAng Li (7046483) 25 July 2024 (has links)
<p dir="ltr">The CFD-CAA method combines computational fluid dynamics (CFD) and computational aeroacoustics (CAA) techniques to analyze the interaction between fluid flow and the generation and propagation of sound. CFD is primarily concerned with simulating fluid flow patterns, while CAA focuses on predicting noise generation and its propagation in fluids. The CFD-CAA method provides a powerful tool for understanding and predicting the acoustic behavior of turbulent flows. By combining the strengths of CFD and CAA, this approach provides more precise and comprehensive analyses across various fields, thereby contributing to enhanced designs and noise control strategies.</p><p dir="ltr">Within industrial applications, a primary concern is noise source identification. This process enables engineers to locate and quantify the strength of noise sources within a system, facilitating the implementation of more effective strategies during the design process. A novel methodology, computational statistically optimized near-field acoustic holography (C-SONAH), is proposed to virtually identify aeroacoustic sources. Initially, sound pressure is obtained using the CFD-CAA method, followed by the application of the SONAH algorithm to locate acoustic sources and predict the sound field. C-SONAH offers computational advantages over direct CAA methods for simulating sound produced by systems with rotating elements, as CAA analyzes sources on the moving elements, making sound field calculation computationally expensive. The SONAH procedure converts these rotating sources into a series of equivalent stationary planar or cylindrical waves, reducing the number of sources and the time required to compute the sound field from each source. This methodology was demonstrated by characterizing the aerodynamic noise produced by a bladeless fan. The sound pressure level obtained by C-SONAH method was validated by the data predicted by the direct CFD-CAA method. Acoustic maps were reconstructed at different locations and frequencies, revealing that the C-SONAH method can predict noise sources generated by airflow and rotating components within the fan. Thus, it serves as an effective tool for understanding the aeroacoustic noise generation mechanism and guiding the design optimization of similar products.</p><p dir="ltr">The CFD-CAA method is also a powerful tool for design optimization. Computational simulations are typically less expensive and time-consuming than building and maintaining experimental setups, particularly for large or complex projects. Additionally, simulations reduce the need for multiple physical prototypes, which can shorten the development cycle. CFD-CAA simulations provide detailed flow and acoustic field data, including variables that may be difficult or impossible to measure experimentally, such as pressure distributions, velocity fields, and turbulent structures. In this dissertation, aeroacoustic characteristics and flow field information of vortex whistles were investigated using the CFD-CAA method. The simulation results clearly illustrate the swirling motion created in the vortex whistle cylinder and also demonstrate the linear frequency versus flow rate relationship characteristic of the whistle. The design of the vortex whistle was optimized based on the acoustic response and flow resistance by both simulations and experiments. The results suggest that the whistle with a thin inlet exhibits the best performance at high flow rates, while the whistle with a scale of 0.5 is the most sensitive to low flow rates, making it suitable for pediatric applications.</p><p dir="ltr">In CFD-CAA simulations, the time step typically cannot be too small due to limited computational resources. This constraint results in an aliasing error in spectral analysis. Consequently, an anti-aliasing operation prior to sampling is necessary to eliminate such errors from the acoustic source terms. In the present study, an anti-aliasing filter based on the compact finite difference formulation was designed within a time-domain, compact filter scheme. This filter was directly applied to the Navier-Stokes solver prior to sampling for CAA analysis. A cavity flow case was simulated to validate this mitigation strategy. The results indicate that the artificial spectral peak induced by aliasing error is removed without affecting other signature peaks. The anti-aliasing filter was also applied to more complex cases for predicting the acoustic field of a vortex whistle. The acoustic field around the vortex whistle, with both constant and variable inlet flow rates, was simulated, and the aliasing peak was successfully removed. Although the peak magnitudes decreased slightly due to the filter, the signature frequencies remained unchanged. Thus, the simulation with anti-aliasing operation can predict acoustic features without introducing aliasing errors, even if the time step is not sufficiently small, thereby significantly reducing simulation time.</p><p dir="ltr">In engineering applications, once noise sources are identified, the subsequent concern is noise reduction. An effective strategy for noise reduction involves acoustical absorbing materials to minimize noise emissions from components. Traditionally, experiments in engineering applications have focused on surface treatments to explore noise control techniques. However, the CFD-CAA method commonly assumes smooth and purely reflective wall surfaces. Consequently, there is growing interest in incorporating impedance boundary conditions into the CFD-CAA method. Since impedance boundary conditions are defined in the frequency domain, while CFD-CAA simulations operate in the time domain, direct implementation is not feasible. To address this issue, several methods have been proposed to define time-domain impedance boundary conditions in simulations. In the present study, a wall softness model was implemented in the CFD-CAA method and to examine a vortex whistle featuring an acoustically permeable surface. In simulations, an impedance boundary condition representing the properties of melamine foam was defined over the surface of a cylindrical cavity. The simulation results were validated against experimental data obtained from a vortex whistle with melamine foam. The findings revealed that the impedance of the melamine foam contributed to noise reduction at high frequencies. Additionally, at low airflow rates, the impedance boundary condition enhanced the signal-to-noise ratio for the low-frequency peak, which is advantageous in clinical applications.</p>
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Adaptation des méthodes et outils aéroacoustiques pour les jets en interaction dans le cadre des lanceurs spatiaux. / Adaptation of aeroacoustic methods and tools for interacting jets in the context of space launchersLangenais, Adrien 07 February 2019 (has links)
Lors d’un lancement spatial, le bruit des jets supersoniques chauds, générés par les moteurs-fusées au décollage et en interaction avec le pas de tir, est dommageable pour le lanceur et en particulier sa charge utile. Par conséquent, les acteurs du spatial cherchent à renforcer leur compréhension et leur maîtrise de cette ambiance acoustique, entre autres grâce à des méthodes et outils numériques. Toutefois, ils ne disposent pas d’une approche numérique globale capable de prendre en compte simultanément la génération fidèle du bruit, la propagation acoustique non-linéaire, les effets d’installation complexes et les géométries réalistes, pourtant inhérents aux applications spatiales. Dans cette optique, cette étude consiste à mettre en place et valider une méthodologie de simulation numérique par couplage fort Navier-Stokes − Euler, puis à l’appliquer à des cas réalistes de bruit de jet supersonique. L’objectif est d’affiner les capacités de prévision et de contribuer à la compréhension des mécanismes de génération de bruit dans de tels jets. Le solveur Navier-Stokes repose sur une méthode LES sur maillage non-structuré et le solveur acoustique sur une méthode de Galerkine discontinue d’ordre élevé sur maillage non-structuré. La méthodologie est tout d’abord évaluée sur des cas académiques visant à valider la simulation par couplage fort. Après des calculs préliminaires, la méthodologie est appliquée à la simulation du bruit d’un jet libre supersonique à Mach 3.1. Une méthode de déclenchement géométrique de la turbulence est implémentée sous la forme d’une marche à la paroi de la tuyère. La simulation aboutit à des estimations du bruit très proches des mesures réalisées au banc MARTEL et met en évidence des effets non-linéaires significatifs ainsi qu’un mécanisme singulier de rayonnement des ondes de Mach. Dans une démarche de progression vers des cas toujours plus réalistes, l’ensemble de l’approche numérique est finalement adaptée avec succès à la simulation du bruit d’un jet en présence d’un carneau. À terme, elle pourra être étendue à des configurations multi-jets réactifs, avec injection d’eau, voire à l’échelle 1. / During a space launch, the noise from hot supersonic jets, generated by rocket engines at liftoff and interacting with the launch pad, is harmful to the launcher and in particular its payload. Consequently, space actors are seeking to strengthen their understanding and control of this acoustic environment through numerical methods and tools, among the others. However, they do not dispose of a comprehensive numerical strategy that can simultaneously take into account accurate noise generation, nonlinear acoustic propagation, complex installation effects and realistic geometries, which are inherent to space applications. For this purpose, the present study consists in setting up and validating a numerical simulation methodology using a Navier-Stokes − Euler two-way coupling approach, then applying it to realistic cases of supersonic jet noise in order to improve prediction capabilities and contribute to the understanding of the noise generation mechanisms in such jets. The Navier-Stokes solver is based on an LES method on unstructured mesh and the acoustic solver on a high-order discontinuous Galerkin method on unstructured mesh. The methodology is first assessed on academic cases to validate the use of the two-way coupling. After preliminary computations, the methodology is applied to the simulation of the noise from a supersonic free jet at Mach 3.1. A geometric turbulence tripping method is implemented via a step at the nozzle wall. The computation leads to noise predictions very close to the experimental measurements performed at the MARTEL test bench and highlights significant nonlinear effects as well as a quite particular Mach waves radiation mechanism. Targeting even more realistic cases, the entire numerical approach is finally successfully adapted to the simulation of the noise from a supersonic jet configuration including a flame trench. In the future, it may be extended to configurations with clustered reactive jets, water injection devices or even at full scale.
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Safety Management Systems (SMS) for aircraft manufacturers and maintainers?Gibbons, Blake January 2014 (has links)
There is much dialogue in the global aviation industry about Safety Management Systems (SMS) and how it should be integrated across all domains of the industry including aircraft design, production, flight operations, overhaul and maintenance, suppliers, service providers, airports, and so forth (Johnson, 2012). Regulators have made significant progress in recent years to implement ICAO’s SMS into airlines, albeit as a required or recommended practice. More recently the regulators are seeking to implement SMS into the aircraft manufacturing and aircraft maintenance domains. This research reviewed regulatory publications from multiple countries to assess the technical makeup of SMS, and understand what regulators are requiring, or recommending, and when. It was found that global regulators accept the ICAO published definition of SMS, but different regulators have varying approaches regarding implementation. However, they are consistent in initially targeting airlines for SMS implementation. SMS comments range from “The best thing since sliced bread” to “Worst thing since the creation of the FAA; I don’t need anyone telling me what’s safe when I already know it; waste of time and money”. This investigation experimented with field tests to connect the engineering, production and airline domains into one ICAO SMS model. Results indicate that because the different domains are risk-specific, the application of one safety risk management model to all domains is not viable. The SMS model applies to airlines because airlines’ primary risk is about operational safety. Aircraft production and maintenance is about production risk – therefore the risk model must be centric to process risk. Field test 3 tailored the ICAO SMS risk architecture to assess and mitigate process risk as applicable to the aircraft manufacturing and maintenance. Although the SMS architecture was usable, the content and focus was significantly adjusted to be production process-risk centric, to the point where the term “SMS’ was deemed out of place. The resulting model was therefore named Production Risk Management System (PRMS). Following the emergence of PRMS from field tests, this investigation reviewed industry, research and regulatory arguments for and against SMS in the airline industry, and correlated those arguments with the benefits and non-benefits of PRMS for the manufacturing and aircraft maintenance domains. The researcher advocates PRMS as a viable model that meets ICAO SMS-like architecture for aircraft production and maintenance. Methods were identified for developing and implementing PRMS, and for evaluating its ROI. If and when “SMS” is truly mandated in these domains, the researcher proposes PRMS as a viable model that should be considered. Furthermore, the researcher proposes that PRMS can be an effective production risk management system that can enhance the organization’s existing QMS, regardless of “SMS” regulations.
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Counterinsurgency the role of paramilitariesEspino, Irineo C. 12 1900 (has links)
Approved for public release; distribution in unlimited. / This thesis examines the role of paramilitary forces in the counterinsurgency operations being launched by the Armed Forces of the Philippines (AFP) against the Communist Party of the Philippines (CPP) and the New People's Army (NPA). The Philippine government and the AFP firmly believe that the present Civilian Armed Force Geographical Unit Active Auxiliary (CAA) is an essential component of the AFP's Operational clear-hold-support methodology. Many scholars have argued that separating the Communist guerrillas from the populace is an important element in winning the counterinsurgency campaign. Isolating the Communist insurgents is done through the creation of local militia. However, some authors contend it would be dangerous for any government to train paramilitary forces because, in the long term, the governments are unsure of the future loyalties of these paramilitary forces. They may currently be working for the government, but as they work and gain skills, these paramilitary forces could use these same skills against the government in the future. Thus, it is quite dangerous to train paramilitary forces. The Philippine paramilitaries are good examples of paramilitary forces being used effectively for counterinsurgency. Their primary task of protecting the communities and the people from the coercive and abusive acts of the Communist insurgents are achieved. They are an effective counterinsurgency force because of proper training as well as command and control. This thesis concludes that the Philippine government and the AFP are headed in the right operational direction for utilizing paramilitary forces for village defense and as the protectors of the people. The paramilitary forces in the Philippines need the proper training as well as command and control in order to make these paramilitary forces effective counterinsurgency forces. / Colonel, Philippine Army
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Technical Verification and Validation of ADS-B/VDL Mode 4 for En-route Airspace and Major Terminal AreasGranberg, Petter, Li, Roger January 2002 (has links)
This report is a technical verification and validation of Automatic Dependent Surveillance – Broadcast (ADS-B) over Very High Frequency Data Link Mode 4 (VDL Mode 4) for the use as surveillance in terminal areas and en-route airspace in non-radar areas. The main objective is to verify that ADS-B/VDL Mode 4 fulfils the technical requirements for an implementation at Kiruna airport, Sweden. Comparison has been made to the current requirements for Secondary Surveillance Radar (SSR). The work in this report has been conducted in three phases: preliminary study, tests and verification and validation. During the preliminary study documents primarily from EUROCONTROL and ICAO were used to find out which requirements that were applicable. The next part consisted of both practical tests and theoretical verification of the VDL Mode 4 performance. Finally the results from the tests were validated and put together in this report. Main conclusion from this report is that ADS-B/VDL Mode 4 fulfils the corresponding SSR requirements. Therefore ADS-B/VDL Mode 4 should be able to serve as primary mean for surveillance in non-radar areas. The results from this report will constitute a part of the technical subset of future safety case for ADS-B in non-radar areas. The complete safety case will be used to authorize ADS-B/VDL Mode 4 in non-radar airspace, both in Sweden and internationally.
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Flerspråkighet och AKK-användning : Upplevt socialt stöd bland flerspråkiga föräldrar med barn i behov av kommunikationsstödSolano, Luz January 2015 (has links)
Studien undersöker flerspråkiga föräldrars erfarenheter av upplevt socialt stöd i föräldrarollen till ett barn med kommunikationsnedsättningar. Forskningsfrågorna berör även vilken betydelse stödet får för kontakten med barnet. Metoden som använts är en sekventiell mixad metod (enkätundersökning och fokusgruppsintervjuer) som utgår från en transformativ strategi. Studiens vetenskapsteoretiska ansats grundar sig i Benno Herzogs teori om social diskursiv exkludering och analysen utgår från Barreras samt Hellers och Swindles grundantaganden om upplevt socialt stöd. Respondenterna deltog i utbildningarna TAKK på Modersmålet och FAMN som anordnades av Projekt TAKK för Språket i Göteborg. Resultaten visar att föräldrarna i studien upplevde socialt stöd utifrån att utbildningarna anpassades och erbjöd: språkstöd på modersmålet, samtal kring användning av alternativ och kompletterade kommunikation (AKK) tillsammans med modersmålet samt samtal om funktionsnedsättningar och samhällstöd. Därutöver visar resultaten att föräldrarna, genom dessa anpassningar, upplever en ökad förståelse för stöddiskursen och stärkt självförtroende. Detta, i sin tur, leder till att föräldrarna upplever större handlingsutrymme i stressrelaterade situationer och en ökad benägenhet att söka och ta emot stöd. / The study examines multilingual parents' experiences of perceived social support when parenting a child with communication impairments. Research questions also deal with the importance of perceived social support for the contact between parents and child. The method used is a sequential mixed methodology (survey and focus group interviews) based on a transformative strategy. The study's scientific theoretical approach is based on Benno Herzog's theory of social discursive exclusion and the analysis starts from Barrera´s and from Heller´s and Swindle´s basic assumptions about perceived social support. The respondents participated in the parenting programs TAKK på Modersmålet and FAMN, that focused the use was of AAC (augmentative and alternative communication) together with the mother tongue, which was organized by the project TAKK för Språket (AAC for multilingualism) in Gothenburg. The results show that the parents in the study perceived social support when the education programs were adapted and offered language support in the mother tongue, discussions about the use of AAC together with the mother tongue (AAC) and information about disabilities as well as information about society’s support system. In addition, the results show that parents, through these adjustments, experience an increased understanding of support discourse and strengthened confidence. This, in turn, leads to parents´ experience of greater freedom of action in stress-related situations and therefor an increased inclination to seek and receive support. / El estudio examina las experiencias de apoyo social percibido por los padres multilingües en relacion al cuidado de un niño con problemas de comunicación. Las preguntas de investigación también se ocupan de la importancia del apoyo social percibido para el establecimiento del contacto entre padres e hijos. El método utilizado es una metodología mixta secuencial (encuesta y grupos de enfoque) basado en una estrategia transformadora. El enfoque teórico científico del estudio se basa en la teoría de la exclusión social discursiva de Benno Herzog y el análisis parte de los conceptos de apoyo social percibido que Barrera y Heller & Swindle describen. Los participantes formaron parte de los cursos para padres TAKK på Modersmålet y FAMN, que enfatizaron el uso de la CAA (comunicación aumentativa y alternativa) junto con la lengua materna, los cuales fueron organizados por el proyecto TAKK för Språket (AAC para el multilingüismo) en Gotemburgo, Suecia. Los resultados muestran que los padres de familia en el estudio perciben apoyo social a partir de que el contenido de los cursos para padres ofrecieron: apoyo en el idioma materno, discusiones sobre el uso de la AAC junto con la lengua materna, información acerca de diferentes discapacidades e información sobre el sistema de apoyo social en Suecia. Además, los resultados muestran que los padres, a través de estos ajustes, experimentan una mayor comprensión del discurso de apoyo a la comunicación lo cual refuerza su autoconfianza. Esto, a su vez, ayudo a los padres a experimentar una mayor libertad de acción ante situaciones estresantes, lo cual aumento la propensión de los padres a buscar y aceptar apoyo.
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Safety Management Systems (SMS) for aircraft manufacturers and maintainers?Gibbons, Blake January 2014 (has links)
There is much dialogue in the global aviation industry about Safety Management Systems (SMS) and how it should be integrated across all domains of the industry including aircraft design, production, flight operations, overhaul and maintenance, suppliers, service providers, airports, and so forth (Johnson, 2012).
Regulators have made significant progress in recent years to implement ICAO’s SMS into airlines, albeit as a required or recommended practice. More recently the regulators are seeking to implement SMS into the aircraft manufacturing and aircraft maintenance domains.
This research reviewed regulatory publications from multiple countries to assess the technical makeup of SMS, and understand what regulators are requiring, or recommending, and when. It was found that global regulators accept the ICAO published definition of SMS, but different regulators have varying approaches regarding implementation. However, they are consistent in initially targeting airlines for SMS implementation. SMS comments range from “The best thing since sliced bread” to “Worst thing since the creation of the FAA; I don’t need anyone telling me what’s safe when I already know it; waste of time and money”.
This investigation experimented with field tests to connect the engineering, production and airline domains into one ICAO SMS model. Results indicate that because the different domains are risk-specific, the application of one safety risk management model to all domains is not viable. The SMS model applies to airlines because airlines’ primary risk is about operational safety. Aircraft production and maintenance is about production risk – therefore the risk model must be centric to process risk. Field test 3 tailored the ICAO SMS risk architecture to assess and mitigate process risk as applicable to the aircraft manufacturing and maintenance. Although the SMS architecture was usable, the content and focus was significantly adjusted to be production process-risk centric, to the point where the term “SMS’ was deemed out of place. The resulting model was therefore named Production Risk Management System (PRMS).
Following the emergence of PRMS from field tests, this investigation reviewed industry, research and regulatory arguments for and against SMS in the airline industry, and correlated those arguments with the benefits and non-benefits of PRMS for the manufacturing and aircraft maintenance domains.
The researcher advocates PRMS as a viable model that meets ICAO SMS-like architecture for aircraft production and maintenance. Methods were identified for developing and implementing PRMS, and for evaluating its ROI. If and when “SMS” is truly mandated in these domains, the researcher proposes PRMS as a viable model that should be considered. Furthermore, the researcher proposes that PRMS can be an effective production risk management system that can enhance the organization’s existing QMS, regardless of “SMS” regulations.
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