Comparison of Upper Neck Loading in Young Adult and Elderly Volunteers During Low Speed Frontal Impacts

Cervical pain and injuries are a major health problem globally. Existing neck injury criteria are based on experimental studies that included sled tests performed with volunteers, post-mortem human surrogates and animals. However, none of these studies have addressed the differences between young adults and elderly volunteers to date. Thus, this work analyzed the estimated axial and shear forces, and the bending moment at the craniocervical junction of nine young volunteers (18–30 years old) and four elderly volunteers (>65 years old) in a low-speed frontal deceleration. Since the calculation of these loads required the use of the mass and moment of inertia of the volunteers' heads, this study proposed new methods to estimate the inertial properties of the head of the volunteers based on external measurements that reduced the error of previously published methods. The estimated mean peak axial force (Fz) was −164.38 ± 35.04 N in the young group and −170.62 ± 49.82 N in the elderly group. The average maximum shear force (Fx) was −224.42 ± 54.39 N and −232.41 ± 19.23 N in the young and elderly group, respectively. Last, the estimated peak bending moment (My) was 13.63 ± 1.09 Nm in the young group and 14.81 ± 1.36 Nm in the elderly group. The neck loads experienced by the elderly group were within the highest values in the present study. Nevertheless, for the group of volunteers included in this study, no substantial differences with age were observed

Aerodinámica de generadores eólicos aerotransportados que operan a gran altitud

Recientemente, un nuevo paradigma asociado a la generación de energía a partir del aire en movimiento ha surgido como alternativa a la generación clásica de energía por medio de turbinas eólicas. Esta nueva tecnología, denominada Airborne Wind Energy (AWE), consiste de dispositivos de generación aerotransportados conectados a una estación terrestre que “cosechan” energía eólica a grandes alturas. Su evolución se ha visto impulsada por su prominente capacidad de producir energía a bajo costo, a una altura donde las corrientes de aire son más fuertes y estables. Si bien diversas instituciones públicas y privadas alrededor del mundo han presentado sus propios diseños fundados en conceptos AWE, esta tecnología se encuentra aún en su estadio inicial; hecho que justifica el desarrollo de herramientas numéricas eficientes que permitan establecer las bases para el diseño de la próxima generación de AWEs. En este trabajo se presenta el desarrollo de una herramienta de simulación numérica para estudiar la aerodinámica no estacionaria y no lineal de un concepto de AWE basado en una plataforma voladora tipo “barrilete” (kiteplane). La configuración del AWE estudiado posee su estación de generación en tierra con un mecanismo de generación de energía que consiste de ciclos de “bombeo” (tracción y retracción). Durante la fase de tracción, el barrilete vuela siguiendo trayectorias con forma de “8” en el espacio, maximizando la tracción sobre el cable y, por lo tanto, produciendo energía a medida que el mismo se desenrolla de la máquina eléctrica. Un punto crucial en el diseño de un AWE eficiente está asociado al cálculo de la fuerza de tracción que se produce en el cable que lo vincula con la estación terrestre, la cual depende directamente de la aerodinámica del barrilete. Con el fin de estudiar la aerodinámica de AWEs y cuantificar la fuerza que estos ejercen sobre el cable de sujeción se adoptó un modelo aerodinámico basado en una versión modificada de la versión 3D del “unsteady vortex-lattice method”, una generalización del conocido “vortex-lattice method”, ampliamente utilizado en flujos incompresibles y estacionarios. Adicionalmente, en este artículo se estudia como las cargas aerodinámicas se ven influenciadas por: i) el ángulo de ataque; ii) la posición de los empenajes horizontal y verticales; y iii) la relación de aspecto, y los ángulos de diedro y de flecha de las alas. Esta línea de investigación está orientada a desarrollar herramientas de simulación para estudiar la dinámica y la aerodinámica de sistemas AWE, y desarrollar sistemas dinámicos finitos para estudiar la aero-servo-elasticidad de dispositivos de generación de energía no convencionales como alternativa a las grandes turbinas eólicas de eje horizontal y/o vertical.Publicado en: Mecánica Computacional vol. XXXV, no. 26Facultad de Ingenierí

Acute acalculous cholecystitis in systemic lupus erythematosus: a rare initial manifestation

ABSTRACT Acute acalculous cholecystitis is a very rare gastrointestinal manifestation in systemic lupus erythematosus and becomes rarer as an initial manifestation. There are only two cases reported. The authors report a 20-year-old black woman that presented acute acalculous cholecystitis revealed by abdominal computed tomography. During hospitalization, she was diagnosed systemic lupus erythematosus. Conservative treatment with antibiotics was performed with complete remission of the symptoms. Corticosteroid was started in ambulatory. Cholecystectomy has been the treatment of choice in acute acalculous cholecystitis as a complication of systemic lupus erythematosus. The patient responded well to conservative treatment, and surgery was not required. This case is unique in the way that corticosteroid was started in ambulatory care. We should not forget that the acute acalculous cholecystitis can be the initial presentation of systemic lupus erythematosus although its occurrence is very rare. Conservative treatment should be considered. Abdominal computed tomography was a determinant exam for better assessment of acute acalculous cholecystitis

Colecistite aguda acalculosa no lúpus eritematoso sistêmico: uma manifestação inicial rara

ResumoA colecistite aguda acalculosa é uma manifestação gastrointestinal rara no lúpus eritematoso sistêmico e ainda mais rara como manifestação inicial. Foram descritos apenas dois casos até o momento. Os autores relatam o caso de uma mulher negra de 20 anos, com quadro de colecistite aguda acalculosa revelada pela tomografia computadorizada do abdome. Durante a hospitalização, a paciente foi diagnosticada com lúpus eritematoso sistêmico. Houve remissão completa dos sintomas após tratamento conservador com antibióticos. Iniciou‐se tratamento com corticosteroides no ambulatório. Embora a colecistectomia seja o tratamento de escolha em casos de colecistite aguda acalculosa como complicação do lúpus eritematoso sistêmico, a paciente respondeu bem ao tratamento conservador; logo, a cirurgia não foi necessária. Este caso é único em razão do modo como o corticosteroide foi iniciado no atendimento ambulatorial. É importante lembrar que a colecistite aguda acalculosa pode ser a manifestação inicial do lúpus eritematoso sistêmico, embora sua ocorrência seja rara. Deve‐se considerar a realização de tratamento conservador. A tomografia computadorizada do abdome foi determinante para que fosse feita uma melhor avaliação da colecistite aguda acalculosa.AbstractAcute acalculous cholecystitis is a very rare gastrointestinal manifestation in systemic lupus erythematosus and becomes rarer as an initial manifestation. There are only two cases reported. The authors report a 20‐year‐old black woman that presented acute acalculous cholecystitis revealed by abdominal computed tomography. During hospitalization, she was diagnosed systemic lupus erythematosus. Conservative treatment with antibiotics was performed with complete remission of the symptoms. Corticosteroid was started in ambulatory. Cholecystectomy has been the treatment of choice in acute acalculous cholecystitis as a complication of systemic lupus erythematosus. The patient responded well to conservative treatment, and surgery was not required. This case is unique in the way that corticosteroid was started in ambulatory care. We should not forget that the acute acalculous cholecystitis can be the initial presentation of systemic lupus erythematosus although its occurrence is very rare. Conservative treatment should be considered. Abdominal computed tomography was a determinant exam for better assessment of acute acalculous cholecystitis

Giant left myxoma with mitral valve obstruction

Abstract We present a case of a patient admitted with acute pulmonary edema. An echocardiogram showed a giant myxoma of the left atrium causing mitral valve obstruction. The patient underwent urgent cardiac surgery for tumor resection. There were no postoperative complications, and the follow‐up was uneventful

Assessment of Madymo Active Human Body Model Kinematics and Dynamics by means of Human Volunteer Response at Low-Speed Frontal Impacts

The aim of this study was to evaluate the capability of the Madymo active HBM to predict the human response by comparing the predictions from the model with the response from human volunteers in frontal-impact tests at 9km/h. The Madymo active HBM correspond to a 50th percentile male model population (standing height=176cm; weight=75.3kg) and the 13 volunteers were selected to have a similar anthropometry (standing height=173.0\ub14.3cm; weight=79.1\ub19.5kg). The influence of a number of important parameters on the Madymo active HBM predictions was evaluated. Those parameters were friction between model and seat pan, reaction time delay and level of co-contraction of neck muscles. The friction was varied between 0.15 and 0.5; the reaction time delay from 0ms to 100ms and the level of co-contraction of neck muscles between a null and full activation. The benchmark considered the displacements of the head, vertebra (C4, T1, T4, T8, T12) and hip, the belt loads, and the estimated upper neck loads in the sagittal plane. It was found that while variations in the RT and CCR levels could cause similar forward excursions, this could also result in an overprediction of the downward excursions; and therefore, the neck muscle controller optimization should always consider both. Two configurations could be implemented in the model to represent the large variation between the volunteers\u27 downward excursion, the first with the closest behaviour to the volunteers\u27 mean and the second closer to the volunteers which showed larger head excursion