Comparative study of combustion and thermal performance of a meso-scale combustor under co- and counter-rotating fuel and oxidizer swirling flows for micro power generators.

Direct energy conversion systems, such as thermophotovoltaic and thermoelectric generators, have received increasing attention in micro power generation. Micro and meso-scale combustors are one of the most core components in these systems. So, developing combustion stabilization technologies for micro or meso-scale combustors is of great importance. In these systems, a hydrocarbon fuel with high energy density is burned in a micro or meso-scale combustor. Many studies have been conducted to explore various combustion stabilization techniques, but as a novelty, in this work, we study the combustion and thermal performance of a meso-scale micro power generator powered by a swirling fuel jet discharging into a co- or counter-rotating air coflow. To do so, we used 3D-printed axial swirlers with double annulus to form the swirling co- and counter-rotating fuel (methane) jet-air coflow configurations at various air and fuel flow rates. Blow-out limit, flame characteristics, combustor mean outer wall temperature, pollutant emissions, emitter efficiency, and normalized temperature standard deviation are investigated in this study. The results show that swirl addition enhances the blow-out limit significantly and co-rotating swirling flows generally enhances the flame blow-out limit when compared with the counter-rotating swirling flows mode at high fuel flow rates. Moreover, the combustor with co-rotating swirling flows has shorter lift-off height and longer flame length. The sensitivity of the flame lift-off height to an increment of the fuel mass flow rate is smaller in co-rotating than in counter-rotating swirling flows (more than 40%). Furthermore, it is observed that under the same operating conditions, co-rotating swirling flows exhibit lower values of CO and NOx in the flue gas and higher values of mean outer wall temperature, combustion efficiency, emitter efficiency, and normalized temperature standard deviation. The enhancement of the emitter efficiency by implementing co-swirl configuration is about 35%, 26%, and 8% for the methane flow rates of 0.050, 0.100, and 0.150slpm, respectively when compared with the counter-swirl mode. The results of this work can provide useful information to choose between co- and counter-rotating flows for combustors of combustion-based micro power generators.

Resultado funcional y mortalidad en pacientes ancianos con amputación mayor de extremidad inferior / Functional results and mortality in elderly patients with major lower limb amputation

Introducción y objetivos: los objetivos de este trabajo han sido conocer qué factores influyen en la recupera ción funcional de los pacientes ancianos que sufren una amputación mayor de una extremidad inferior (AMeI) de etiología vascular y analizar la recuperación de la marcha y de la mortalidad al año de la amputación. Material y métodos: estudio longitudinal observacional de los pacientes mayores de 70 años valorados por el servicio de rehabilitación tras una AMeI desde el 1 enero de 2019 hasta el 1 enero de 2021. Se recogieron las siguientes variables: edad, sexo, etiología, índice de masa corporal, comorbilidad (escala de Charlson), independencia en las AVd básicas (índice de Barthel) y capacidad de marcha (FAC) previas. Al año se analizaron la capacidad de marcha y la mortalidad. Resultados: el estudio se realizó en 45 pacientes con una edad media de 80,3 años (el 64,3 % varones). Todos fueron de etiología vascular. el nivel de amputación fue supracondíleo en 31 pacientes e infracondíleo en 14. Se protetizaron 13. Al año solo caminaban 5 pacientes y habían fallecido 21. Las variables relacionadas con la posibilidad de rehabilitación-protetización fueron: presentar menos comorbilidad (p = 0,004) y tener una mayor independencia funcional y de marcha previa a la amputación (p = 0,000), al igual que las relacionadas con la no mortalidad, con p = 0,005 y p = 0,017 (p = 0,013), respectivamente. Conclusión: la mejor situación funcional y clínica previa a la amputación son los factores más importantes tanto para la posibilidad de rehabilitación protésica como para la supervivencia de nuestros ancianos amputados.(AU)

Introduction and objectives: the objectives of this work have been to know what factors influence in thefunctional recovery of elderly patients who suffer a major lower limb amputation (SMA) of vascular etiology andto analyze the recovery of gait and mortality one year after the amputation. Material and methods: longitudinal observational study of patients older than 70 years assessed by the Reha-bilitation Service after SMA from January 1, 2019 to January 1, 2021. The following variables were collected: Age, sex, etiology, body mass index, comorbidity (Charlson scale), independence in basic ADL (Barthel index) and previous walking capacity (FAC). One year later, walking ability and mortality. Results: the study was conducted in 45 patients with a mean age of 80.3 years, 64.3 % male. All were of vascularetiology. The level of amputation was: supracondylar 31 and infracondylar 14. After a year, only 5 patients werewalking and 21 had died. The variables related to the possibility of rehabilitation-fitting were: having less comorbidity (p = 0.004) as well as having greater functional and gait independence prior to amputation (p = 0.000), as well as those related to nomortality, with a (p = 0.005) and (p = 0.017) (p = 0.013) respectively. Conclusion: the best functional and clinical situation prior to amputation are the most important factors both forthe possibility of prosthetic rehabilitation and for the survival of our elderly amputees.(AU)

B5GEMINI: AI-Driven Network Digital Twin.

Network Digital Twin (NDT) is a new technology that builds on the concept of Digital Twins (DT) to create a virtual representation of the physical objects of a telecommunications network. NDT bridges physical and virtual spaces to enable coordination and synchronization of physical parts while eliminating the need to directly interact with them. There is broad consensus that Artificial Intelligence (AI) and Machine Learning (ML) are among the key enablers to this technology. In this work, we present B5GEMINI, which is an NDT for 5G and beyond networks that makes an extensive use of AI and ML. First, we present the infrastructural and architectural components that support B5GEMINI. Next, we explore four paradigmatic applications where AI/ML can leverage B5GEMINI for building new AI-powered applications. In addition, we identify the main components of the AI ecosystem of B5GEMINI, outlining emerging research trends and identifying the open challenges that must be solved along the way. Finally, we present two relevant use cases in the application of NDTs with an extensive use of ML. The first use case lays in the cybersecurity domain and proposes the use of B5GEMINI to facilitate the design of ML-based attack detectors and the second addresses the design of energy efficient ML components and introduces the modular development of NDTs adopting the Digital Map concept as a novelty.

AFOROS: A Low-Cost Wi-Fi-Based Monitoring System for Estimating Occupancy of Public Spaces.

Estimating the number of people present in a given venue in real-time is extremely useful from a security, management, and resource optimization perspective. This article presents the architecture of a system based on the use of Wi-Fi sensor devices that allows estimating, almost in real-time, the number of people attending an event that is taking place in a venue. The estimate is based on the analysis of the "probe request" messages periodically transmitted by smartphones to determine the existence of Wi-Fi access points in the vicinity. The method considers the MAC address randomization mechanisms introduced in recent years in smartphones, which prevents the estimation of the number of devices by simply counting different MAC addresses. To solve this difficulty, our Wi-Fi sensors analyze other fields present in the header of the IEEE 802.11 frames, the information elements, to extract a unique fingerprint from each smartphone. The designed system was tested in a set of real scenarios, obtaining an estimate of attendance at different public events with an accuracy close to 95%.

Unexpected Propagation of Ultra-Lean Hydrogen Flames in Narrow Gaps.

Very lean hydrogen flames were thought to quench in narrow confined geometries. We show for the first time how flames with very low fuel concentration undergo an unprecedented propagation in narrow gaps: H_{2}-air flames can survive very adverse conditions by breaking the reaction front into isolated flame cells that travel steadily in straight lines or split to perform a fractal-like propagation that resembles the pathway of starving fungi or bacteria. The combined effect of hydrogen mass diffusivity and intense heat losses act as the two main mechanisms that explain the experimental observations.

[Changes in vertical HIV transmission: comparison between 1994 and 2004]. / Cambios en la transmisión vertical del virus de la inmunodeficiencia humana: comparación de los años 1994 y 2004.

BACKGROUND AND OBJECTIVE: Vertical transmission (VT) is the main route of human immunodeficiency virus (HIV) infection in children. Since the publication of PACTG 076 study in 1994, several preventive methods against the vertical transmission of the HIV have been developed. In this study, we compare the clinical and epidemiological profile of HIV-infected pregnant women and the VT rate in the years 1994 and 2004. PATIENTS AND METHOD: We looked at maternal, obstetric and pediatric variables of HIV-infected women and their children, born in 1994 and 2004, who were followed in Hospital La Paz. RESULTS: We included 40 mother-infant couples in 1994 and 35 couples in 2004. The HIV vertical transmission rate was 35% in 1994 and 0% in 2004. We did not find changes in Hepatitis C virus (HCV) vertical transmission. In 1994, HIV-infected mothers had a more advanced HIV-disease and the major route of HIV-transmission was the intravenous drug use. Vaginal delivery was more frequent and rupture of membranes was longer than in 2004. The main route of maternal HIV infection in 2004 was sexual contact. In this same year, the use of combination antiretroviral therapy, even during pregnancy, was generalized, the elective cesarean section was the most frequent form of delivery, and every newborn received zidovudine. CONCLUSIONS: In the last decade, there have been important epidemiological changes in HIV-infected mothers in our society. The administration of antiretroviral therapy during pregnancy and to the newborn, as well as other obstetric strategies, can prevent HIV vertical transmission. Nevertheless, we did not find any change in the risk of HCV vertical transmission.

Cambios en la transmisión vertical del virus de la inmunodeficiencia humana: comparación de los años 1994 y 2004 / Changes in vertical HIV transmission: comparison between 1994 and 2004

Fundamento y objetivo: Desde la publicación del estudio PACTG 076 en 1994 se han desarrollado medidas profilácticas frente a la transmisión vertical (TV) del virus de la inmunodeficiencia humana (VIH), principal vía de infección infantil por el VIH. Se comparan las características de las embarazadas infectadas por el VIH y las tasas de TV del VIH de 1994 y las de 2004. Pacientes y método: Se estudian las variables maternas, obstétricas y pediátricas de mujeres infectadas por el VIH y sus hijos, nacidos en 1994 y 2004 y seguidos en el Hospital La Paz. Resultados: Se incluye a 40 parejas madre-hijo de 1994 y 35 de 2004. La tasa de TV del VIH fue del 35% en 1994 y del 0% en 2004. No se observaron cambios en la TV del virus de la hepatitis (VHC). En 1994 las madres infectadas por el VIH estaban más sintomáticas y la vía de infección era el uso de drogas intravenosas, el parto vaginal era el más frecuente, y el tiempo de bolsa rota, más prolongado. En 2004 la vía de infección materna por el VIH fue principalmente sexual, se ha generalizado el tratamiento antirretroviral combinado en la mujer seropositiva, en la gestación, la cesárea programada era más frecuente y todos los neonatos recibieron zidovudina. Conclusiones: En una década se han producido importantes cambios epidemiológicos en las gestantes infectadas por el VIH en nuestro medio. La administración de antirretrovirales en el embarazo y al neonato y las medidas obstétricas preventivas pueden evitar la TV del VIH. No obstante, no se ha observado modificación en el riesgo de TV del VHC

Background and objective: Vertical transmission (VT) is the main route of human immunodeficiency virus (HIV) infection in children. Since the publication of PACTG 076 study in 1994, several preventive methods against the vertical transmission of the HIV have been developed. In this study, we compare the clinical and epidemiological profile of HIV-infected pregnant women and the VT rate in the years 1994 and 2004. Patients and method: We looked at maternal, obstetric and pediatric variables of HIV-infected women and their children, born in 1994 and 2004, who were followed in Hospital La Paz. Results: We included 40 mother-infant couples in 1994 and 35 couples in 2004. The HIV vertical transmission rate was 35% in 1994 and 0% in 2004. We did not find changes in Hepatitis C virus (HCV) vertical transmission. In 1994, HIV-infected mothers had a more advanced HIV-disease and the major route of HIV-transmission was the intravenous drug use. Vaginal delivery was more frequent and rupture of membranes was longer than in 2004. The main route of maternal HIV infection in 2004 was sexual contact. In this same year, the use of combination antiretroviral therapy, even during pregnancy, was generalized, the elective cesarean section was the most frequent form of delivery, and every newborn received zidovudine. Conclusions: In the last decade, there have been important epidemiological changes in HIV-infected mothers in our society. The administration of antiretroviral therapy during pregnancy and to the newborn, as well as other obstetric strategies, can prevent HIV vertical transmission. Nevertheless, we did not find any change in the risk of HCV vertical transmission

Quiste epidermoide esplénico gigante / Giant epidermoid splenic cyst

Los quistes epidermoides esplénicos son tumoraciones benignas muy poco frecuentes. El tratamiento de éstas ha evolucionado con el tiempo y tiende a ser cada vez menos agresivo y más conservador. Nosotros presentamos a través del caso clínico de una mujer joven con un quiste epidermoide gigante, que requirió la realización de una esplenectomía total vía abierta, una revisión de la bibliografía sobre las tumoraciones congénitas benignas de bazo (AU)

Giant epidermoid splenic cysts are rare benign tumors. Their treatment is becoming increasingly less aggressive and more conservative. We report the case of a young woman with a giant epidermoid cyst, which required open total splenectomy, and review the literature on benign congenital tumors of the spleen (AU)

[Giant epidermoid splenic cyst]. / Quiste epidermoide esplénico gigante.

Giant epidermoid splenic cysts are rare benign tumors. Their treatment is becoming increasingly less aggressive and more conservative. We report the case of a young woman with a giant epidermoid cyst, which required open total splenectomy, and review the literature on benign congenital tumors of the spleen.

Apendicectomía laparoscópica: nuestra vía de abordaje / Laparoscopic appendectomy. Our original approach

Objetivo: Presentar la experiencia con apendicectomía laparoscópica. Determinar la limitación de la técnica en relación al tipo de abordaje. Pacientes y método: Entre enero de 1999 y septiembre de 2002 se revisó una serie personal de 100 pacientes en quienes se realizó apendicectomía laparoscópica en 98 casos y abierta en dos. El diagnóstico se apoyó en la ecografía abdominal para descartar apendicitis complicada. Técnica quirúrgica: Se utilizó el trocar de Hasson umbilical y dos puertos, uno de 5 mm púbico para exposición del apéndice y otro en fosa iliaca izquierda de 10 mm sustituido por uno de 5 mm, al disponer de una óptica de 5 mm y cero grados. La extracción del apéndice siempre fue con bolsa por el acceso umbilical. Resultados: El tiempo de cirugía fue de 55 minutos. Como complicaciones se presentaron una infección de herida quirúrgica y una eventración. La tasa de apendicectomía en blanco fue 8/100. Conclusión: La apendicectomía laparoscópica es un tratamiento alternativo de la apendicitis aguda no complicada en nuestro medio; puede realizarse sin dificultades e independientemente de la disposición variable de los trocares de entrada

Patología más frecuente en la consulta externa de gastroenterología / More frequent pathology in the external consultation on gastroenterology service

Las enfermedades gastroenterológicas son muy frecuentes, sean de carácter anatómico o funcional. El término dispepsia es muy utilizado y define en forma vaga la patología subyacente; tiene una prevalencia de 250 por 1000 habitantes, con un pico entre los 25 y 45 años de edad. Se estudian 300 pacientes de la consulta externa de un servicio de gastroenterología para evaluar la patología más frecuente. Se encuentra un 23,70% de gastroduodenopatías funcionales, hemorroides 9,09%, gastritis 9,09%, hernia hiatal 5,82%

Enfermedad de Crohn / Crohn's disease

Se presenta el caso de un paciente de 48 años de edad, quien ingresa al Hospital Rísquez de Caracas con un cuadro de pseudo-obstrucción intestinal, motivo por el cual fue sometido a una Laparotomía Exploradora, liberación de adherencias, despegamiento de bridas a la vejiga y al ciego. resección de tumoración y trayecto fibroso que se extendía desde el íleon terminal al ciego y a la vejiga y de lesión en salto en el yeyuno proximal al resecar la lesión se practicó anastomosis término-terminal yeyuno-yeyunal y yeyuno-ileal. El estudio histopatológico fue compatible con una enfermedad de Crohn. Actualmente, después de cuatro (4) años de haber sido intervenido, el paciente se encuentra en perfectas condiciones de salud

Campylobacter pylori: estudio retrospectivo en 150 biopsias gástricas con gastritis crónica tipo B / Campylobacter pylori retrospective study in 150 biopsies with chronic type B gastritis

Se hace un estudio retrospectivo de 150 biopsias gástricas con la coloración de Warthin Starry y el diagnóstico de gastritis crónica tipo B activa e inactiva, se encontró en 113 casos el 76% la presencia de Campylobacter pylori. De ese total 72% fueron mujeres y 41 hombres con una relación mujer-hombre de 1.75:1. Se discute la patogenia de la enfermedad. La bacteria en el corte del tejido observado con el microscopio electrónico mostró dos flagelos completos y uno imcompleto, en los primeros se evidenció la vaina que los cubre y la dilatación distal que estuvo precedida de una zona electro densa. Hasta nuestro conocimiento actual este hallazgo morfológico en tejido, no había sido descrito. Palabras claves: Gastritis-Campylobacter pylori