Comparison of Three Angle of Attack (AOA) Indicators: A Usability Study

Angle of Attack (AOA) is an important aeronautical concept used to understand the performance status of an aircraft during different flight stages. The Federal Aviation Administration (FAA) has indicated the importance of developing and encouraging the use of affordable AOA based systems to increase inflight safety. Embry-Riddle Aeronautical University\u27s flight department decided to install AOA indicators in its fleet of Cessna 172S, to increase safety and to help student pilots better understand this important concept. This paper presents a review of AOA, visual display design principles, and usability. This experimental study examined three different AOA indicators provided by the flight department. The goal was to conduct a usability study in order to understand which of these indicators was better suited for student training. Instructor pilots were used as participants in a series of flights, in which they were asked to perform different maneuvers in which using AOA indicators was thought to help increasing stall awareness and performance. At the end of each flight participants were asked to complete a series of surveys (including an adaptation of the system usability scale) and to provide comments in order to understand their preferences related to AOA indicators. The analysis of the data shows significant differences between the indicators. Discussion of the results and recommendations for future studies are also covered

User Interface Design Recommendations for Small Unmanned Aircraft Systems (sUAS)

The number of small unmanned aircraft systems (sUAS) has dramatically increased in recent years. As a consequence, the number of incidents involving manned and unmanned aircraft has soared. For this reason, the Federal Aviation Administration has released a notice of proposed rulemaking to delineate the operational limitations for sUAS. Many efforts have been introduced to regulate the operations of these systems and educate operators. Despite these efforts, there are no clear standards related to the type of information that should be available to operators, or how this information should be conveyed during flight operations. For this reason we present a series of design recommendations in order to encourage a discussion within the aviation community about the need to develop visual displays that could aid sUAS users unfamiliar with the intricacies of a complex air system to operate in a safe and efficient manner

Essays on Information Frictions, Prices and Unemployment

I investigate the effects of information frictions in price setting decisions. I show that firms' output prices and wages are less sensitive to aggregate economic conditions when firms and workers cannot perfectly understand (or know) the aggregate state of the economy. Prices and wages respond with a lag to aggregate innovations because agents learn slowly about those changes, and this delayed adjustment in prices makes output and unemployment more sensitive to aggregate shocks. In the first chapter of this dissertation, I show that workers' noisy information about the state of the economy help us to explain why real wages are sluggish. In the context of a search and matching model, wages do not immediately respond to a positive aggregate shock because workers do not (yet) have enough information to demand higher wages. This increases firms' incentives to post more vacancies, and it makes unemployment volatile and sensitive to aggregate shocks. This mechanism is robust to two major criticisms of existing theories of sluggish wages and volatile unemployment: the flexibility of wages for new hires and the cyclicality of the opportunity cost of employment. Calibrated to U.S. data, the model explains 60% of the overall unemployment volatility. Consistent with empirical evidence, the response of unemployment to TFP shocks predicted by my model is large, hump-shaped, and peaks one year after the TFP shock, while the response of the aggregate wage is weak and delayed, peaking after two years. In the second chapter of this dissertation, I study the role of information frictions and inventories in firms' price setting decisions in the context of a monetary model. In this model, intermediate goods firms accumulate output inventories, observe aggregate variables with one period lag, and observe their nominal input prices and demand at all times. Firms face idiosyncratic shocks and cannot perfectly infer the state of nature. After a contractionary nominal shock, nominal input prices go down, and firms accumulate inventories because they perceive some positive probability that the nominal price decline is due to a good productivity shock. This prevents firms' prices from decreasing and makes current profits, households' income, and aggregate demand go down. According to my model simulations, a 1% decrease in the money growth rate causes output to decline 0.17% in the first quarter and 0.38% in the second followed by a slow recovery to the steady state. Contractionary nominal shocks also have significant effects on total investment, which remains 1% below the steady state for the first 6 quarters

Differences between Atrial Fibrillation Detected before and after Stroke and TIA: A Systematic Review and Meta-Analysis

Background: Preliminary evidence suggests that patients with atrial fibrillation (AF) detected after stroke (AFDAS) may have a lower prevalence of cardiovascular comorbidities and lower risk of stroke recurrence than AF known before stroke (KAF). Objective: We performed a systematic search and meta-analysis to compare the characteristics of AFDAS and KAF. Methods: We searched PubMed, Scopus, and EMBASE for articles reporting differences between AFDAS and KAF until June 30, 2021. We performed random- or fixed-effects meta-analyses to evaluate differences between AFDAS and KAF in demographic factors, vascular risk factors, prevalent vascular comorbidities, structural heart disease, stroke severity, insular cortex involvement, stroke recurrence, and death. Results: In 21 studies including 22,566 patients with ischemic stroke or transient ischemic attack, the prevalence of coronary artery disease, congestive heart failure, prior myocardial infarction, and a history of cerebrovascular events was significantly lower in AFDAS than KAF. Left atrial size was smaller, and left ventricular ejection fraction was higher in AFDAS than KAF. The risk of recurrent stroke was 26% lower in AFDAS than in KAF. There were no differences in age, sex, stroke severity, or death rates between AFDAS and KAF. There were not enough studies to report differences in insular cortex involvement between AF types. Conclusions: We found significant differences in the prevalence of vascular comorbidities, structural heart disease, and stroke recurrence rates between AFDAS and KAF, suggesting that they constitute different clinical entities within the AF spectrum. PROSPERO registration number is CRD42020202622

Estudio de prefactibilidad para Intermediary una plataforma de bróker comercial en el Oriente Antioqueño

Intermediary is a project that arose from the need of small and medium-sized companies in Eastern Antiqueño to grow and expand their markets as they responded in interviews and surveys, additionally Calderón Quijije and Abad Alvarado, (2017) but these companies find it difficult to expand because they do not know how to get new customers or suppliers, therefore, Intermediary is the solution, because it is a commercial broker that allows them to expand their portfolio of products and increase their sales through a web platform that can be used from anywhere, where they can publish their products and search for raw materials or supplies that they need, all from a mobile device or computer, additionally, Intermediary provides the brokerage service from the beginning of the negotiation until its culmination, providing advice and support throughout this process.Rionegro, Antioqui

Meigs syndrome: literature review of a case report

Ovarian cancer is the presence of one or multiple tumors, which appears in one or both ovaries. These tumors are usually classified as epithelial and non-epithelial. Sex cord-stromal tumors are a group of benign and malignant neoplasms that develop from the sexual cord. Many are functional and therefore have hormonal secretions. Meigs syndrome is defined by the presence of pleural effusion and ascites in association with an ovarian tumor. We present a case of a 55 years old patient who was admitted due to a pelvic tumor, exudative pleural effusion that was difficult to manage, and ascites. A benign ovarian stromal tumor associated with elevated Ca 125 was diagnosed. After the management of the effusions, a 20x20x10 cm ovarian tumor resection was performed by laparotomy, and a transoperative report of a thecoma/fibroma type stromal tumor was received. Meigs syndrome occurs in 1% of ovarian tumors, being very rare before the third decade of life, the pathogenesis of ascites and pleural effusion could be related to the imbalance of hydrostatic forces between arterial flow and lymphovenous drainage culminating in a stromal transudate. Treatment of this syndrome should be focused on tumor debulking surgery and symptomatic treatments such as chest tubes and pleurodesis

Aplicacion de aboliquido en suelos de la granja de la Universidad del Magdalena en el cultivo del pimenton (capsicum annum l.)

La presente investigación se realizó en la granja experimental de la Universidad del Magdalena, municipio de Santa Marta, departamento del Magdalena, geográficamente se encuentra ubicada entre las coordenadas 74° 07" y 74° 12 de longitud oeste con respecto al meridiano de Grenwich; y a los 11°11" y 11°15" de latitud norte con respecto al paralelo del ecuador. Con una precipitación promedio de 615 mm anuales, temperatura promedio de 30°c, una humedad relativa entre 70 y 72%. El clima de esta zona es considerado muy caliente, de estepa con vegetación xerofítica. El ensayo se realizó entre los meses de Octubre a Abril del 2002 al 2003, para una duración de seis meses aproximadamente. El diseño que se utilizo fue el de bloques al azar y pruebas complementarias de ajustes de polinomios ortógonales, con cinco tratamientos y cuatro replicas, para un total de 20 unidades experimentales. Cada parcela tenía un área de 2,4 metros de ancho por 3 metros de largo. El área total del ensayo fue 252 m cuadrados. El espacio entre planta para todos los tratamientos fue de 0.60 entre surco 0.30 metros entre plantas dejando 15 cm de borde de cada era para un total de 36 plantas por eras. El material vegetal empleado fue la semilla de ají pimentón de la variedad California woonder (Capsicum annum L). Para la fertilización se aplicó el fertilizante aboliquido en dosis de 0, 60, 120, 180 y 240 L / Has de fertilizante inorgánico, al inicio de la aparición de las primeras estructuras florales. Se analizaron las siguientes características: altura de la planta, grosor del tallo, ancho del fruto, largo del fruto y peso del fruto