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Caused by four serotypes, dengue fever is a major public health concern worldwide. Current modeling efforts have mostly focused on primary and heterologous secondary infections, assuming that lifelong immunity prevents reinfections by the same serotype. However, recent findings challenge this assumption, prompting a reevaluation of dengue immunity dynamics.In this study, we develop a within-host modeling framework to explore different scenarios of dengue infections. Unlike previous studies, we go beyond a deterministic framework, considering individual immunological variability. Both deterministic and stochastic models are calibrated using empirical data on viral load and antibody (IgM and IgG) concentrations for all dengue serotypes, incorporating confidence intervals derived from stochastic realizations.With good agreement between the mean of the stochastic realizations and the mean field solution for each model, our approach not only successfully captures primary and heterologous secondary infection dynamics facilitated by antibody-dependent enhancement (ADE) but also provides, for the first time, insights into homotypic reinfection dynamics. Our study discusses the relevance of homotypic reinfections in dengue transmission at the population level, highlighting potential implications for disease prevention and control strategies.

Background/Objective: Paragangliomas are rare neuroendocrine tumors that primarily arise in the adrenal gland. Head and neck paragangliomas comprise approximately 3% of all extra-adrenal paragangliomas, with a majority of those being found in the carotid body. Recurrent laryngeal nerve paragangliomas are exceedingly rare, with only 2 reported cases found in literature review. Here, we will present the third. Case Report: The patient is a 46-year-old woman with a history of a right thyroid nodule that had been previously biopsied benign with “paucity of diagnostic material.” Neck ultrasonography revealed a 7.4 cm nodule that demonstrated interval growth over a 2-year period, so it was recommended to proceed with right thyroid lobectomy and isthmusectomy. During resection, the recurrent laryngeal nerve appeared to “disappear” into the nodule, and it was resected along with the nodule to ensure proper margins. The nerve was reconstructed with an ansa cervicalis interposition graft, and the nodule was sent to pathology. Pathology revealed that the nodule was a 4.8 cm paraganglioma of the recurrent laryngeal nerve. Discussion: Paragangliomas of the head and neck are exceedingly rare. In patients who present with symptoms of dysphagia or dysphonia, further workup, including laryngoscopy and magnetic resonance imaging, could potentially identify and allow for appropriate planning for surgical resection. Conclusion: In rare cases, consideration of paraganglioma as part of the differential for thyroid nodules may assist with planning of surgery but will unlikely alter treatment.

This paper presents a mathematical model of the cardiovascular system (CVS) designed to simulate both normal and pathological conditions within the systemic circulation. The model introduces a novel representation of the CVS through a change of coordinates, transforming it into the “quadratic normal form”. This model facilitates the implementation of a sliding mode observer (SMO), allowing for the estimation of system states and the detection of anomalies, even though the system is linearly unobservable. The primary focus is on identifying valvular heart diseases, which are significant risk factors for cardiovascular diseases. The model’s validity is confirmed through simulations that replicate hemodynamic parameters, aligning with existing literature and experimental data.

In this article, a toolbox based on a monitoring and control interface (MCI) is presented and applied in a heat exchanger. The MCI was programed in order to realize sensor fault detection and isolation and fault tolerance using virtual sensors. The virtual sensors were designed from model-based high-gain observers. To develop the control task, different kinds of control laws were included in the monitoring and control interface. These control laws are PID, MPC and a non-linear model-based control law. The MCI helps to maintain the heat exchanger under operation, even if a temperature outlet sensor fault occurs; in the case of outlet temperature sensor failure, the MCI will display an alarm. The monitoring and control interface is used as a practical tool to support electronic engineering students with heat transfer and control concepts to be applied in a double-pipe heat exchanger pilot plant. The method aims to teach the students through the observation and manipulation of the main variables of the process and by the interaction with the monitoring and control interface (MCI) developed in LabVIEW©. The MCI provides the electronic engineering students with the knowledge of heat exchanger behavior, since the interface is provided with a thermodynamic model that approximates the temperatures and the physical properties of the fluid (density and heat capacity). An advantage of the interface is the easy manipulation of the actuator for an automatic or manual operation. Another advantage of the monitoring and control interface is that all algorithms can be manipulated and modified by the users.

Resumen: En el presente trabajo se estudia el efecto que ejerce la concentración del catalizador Fe+2 en un rango de pH comprendido entre 4 y 6.5 sobre el tiempo de transformación del Fe(OH)3 a nano hematita, mediante el método de precipitación controlada (MPC). La cantidad de catalizador [Fe+2]/[Fe+3] utilizada en los ensayos fue 0.2, 0.5 y 0.7, respectivamente. El producto de la síntesis se caracterizó mediante DRX, SEM y DLS. Los resultados obtenidos mostraron que la adición del ión Fe+2 a pH = 5, favoreció el mecanismo de disolución/re-precipitación y redujo el tiempo de transformación de fase de 12 a 4 horas. Cabe indicar que el pH inicial de la reacción fue determinante en el tiempo de transformación de fase ya que al disminuir su valor, la solubilidad del Fe(OH)3 aumentó, las reacciones de disolución se aceleraron y la velocidad de recuperación del ion Fe+2 se incrementó. Finalmente, se evaluó la capacidad de las nanopartículas de hematita sintetizadas para remover Cr(VI) de soluciones sintéticas. Para ello, se utilizó una relación en masa de [Fe2O3/Cr+6] entre 150 y 250 a valores de pH comprendidos entre 2 y 6. El porcentaje de Cr (VI) removido se determinó mediante espectroscopía de absorción atómica. La mayor cantidad de Cr(VI) removido fue del 84.5%, la cual se alcanzó utilizando una carga [Fe2O3/Cr+6] igual a 250 y un pH de 2. Abstract: In this paper we study the influence of Fe+2 concentration in a pH rangebetween 4.0 and 6.5 as a catalyst on the phase transformation of Fe(OH)3 to nanosizedhematite. The used procedure was the chemical controlled precipitation method (CPM). Theamount of catalyst [Fe+2]/[Fe+3] used in the tests was 0.2, 0.5 and 0.7, respectively. Then theproduct of this synthesis was characterized by XRD, SEM and DLS. The results showed thatthe addition of Fe+2 ion at pH= 5.0, favored the mechanism of dissolution/re-precipitationand reduced the time of phase transformation from 12 to 4 hours. It was also noted that thesolubility of Fe(OH)3, the dissolution reactions and the Fe+2 recovery rate increased at low pH.Finally, we evaluated the capacity of hematite nanoparticles to remove Cr (VI) from syntheticsolutions. We used a mass ratio of [Fe2O3/Cr+6] between 150 and 250 and, pH values between2 and 6. The percentage of Cr (VI) removed was determined by atomic absorption spectroscopy.The results showed that the maximum chromium adsorption was 84.5%. That occurred at pH= 2 using a load of [Fe2O3/Cr+6] equal to 250.

Los filtros activos paralelos (FAP’s) son sistemas electrónicos usados para mejorar la calidad de la energía, ya que se diseñan para suministrar las componentes armónicas de corriente que la carga requiere, de manera que la red eléctrica suministra solamente la componente fundamental. Estos filtros son no lineales debido a la señal de control y variantes en el tiempo por la naturaleza variable de algunos de sus componentes. En una primera aproximación, se diseñan controladores nominales basados en pasividad considerando parámetros conocidos; sin embargo, cuando algunos parámetros del sistema cambian puede presentarse un comportamiento caótico. En este artículo se usa una ley de control robusto basada en la técnica de rediseño de Lyapunov para diseñar una señal de control adicional que enfrente las incertidumbres paramétricas y haga que el intervalo de variación de parámetros sea mayor sin que se presente comportamiento caótico en el sistema. Se presentan el diseño del control robusto y simulaciones para ilustrar el desempeño del sistema.