A fractional PI observer for incommensurate fractional order systems under parametric uncertainties.

The problem of state observation in incommensurate fractional order systems has been poorly studied. Currently some observers that have been proposed are based on a copy of the system, which causes them to be highly dependent on the system parameters, additionally they are redundant (estimate variables that are available). So this paper proposes a novel fractional observer against parametric uncertainties for a certain type of incommensurate fractional order systems. The fractional observer design is based on a property concerning observability in incommensurate fractional order systems which allows us to construct the observer only considering the available output and its fractional derivatives. On the other hand, the convergence analysis of the observation error is carried out using a particular approach of fractional order systems related to the Global Mittag-Leffler boundedness. We prove that there is a compact set GMLA (Globally Mittag-Leffler Attractive, according to Definition 4) where the system that represents the observation error dynamics is attractive and we also prove that the observation error is uniformly bounded. Additionally, the fractional observer is model-free i.e., a system copy is not required, this gives robustness in spite of parametric uncertainties and it is also reduced order therefore one observer must be designed for each variable that we want to estimate consequently the observer is non-redundant (no estimation of variables that are already available). Moreover, our proposed fractional observer can be designed for commensurate fractional order systems and we also show that if we consider integer derivative order, the proposed fractional observer presents certain properties. Finally, in order to show the effectiveness of the proposed fractional observer, an incommensurate fractional order Rössler hyperchaotic system is considered as a numerical example and an incommensurate fractional model of the COVID-19 pandemic as a real-world application.

A globally Mittag-Leffler bounded high-gain observer for systems with unknown dynamics and noisy measurements.

In this work, we present a globally Mittag-Leffler bounded high-gain observer for fractional order nonlinear systems with unmodeled dynamics and additive measurement noise at the output. Our proposal starts from an alternative representation of the fractional order system, whose output does not depend on the additive measurement noise and in which the original system's output is treated as an additional state variable. This representation allows us two things: 1) to simultaneously estimate the state variables and the uncertain term and 2) to incorporate into the design scheme a fractional integral-type contribution, which is useful to give robustness against the measurement noise and the unmodeled dynamics, as well as to attenuate the noise amplification, typical of any high-gain observer. Through the corresponding mathematical analysis, we prove that the estimation error of the proposed observer is uniformly bounded and converges asymptotically to a globally Mittag-Leffler compact attractive set, this is, the proposed observer is globally Mittag-Leffler bounded. Additionally, we show that under certain conditions, such as an integer derivation order or the absence of measurement noise, the proposed observer exhibits some particular properties. Finally, we consider a continuously stirred biochemical reactor to exemplify our design methodology. The numerical results confirm that the observer is able to accurately estimate the state variables as well as the uncertainty term of the fractional model. In other words, the globally Mittag-Leffler bounded high-gain observer is robust against measurement noise and uncertainties.

An algorithm for the robust estimation of the COVID-19 pandemic's population by considering undetected individuals.

Due to the current COVID-19 pandemic, much effort has been put on studying the spread of infectious diseases to propose more adequate health politics. The most effective surveillance system consists of doing massive tests. Nonetheless, many countries cannot afford this class of health campaigns due to limited resources. Thus, a transmission model is a viable alternative to study the dynamics of the pandemic. The most used are the Susceptible, Infected and Removed type models (SIR). In this study, we tackle the population estimation problem of the A-SIR model, which takes into account asymptomatic or undetected individuals. By means of an algebraic differential approach, we design a model-free (no copy system) reduced-order estimation algorithm (observer) to determine the different non-measured population groups. We study two types of estimation algorithms: Proportional and Proportional-Integral. Both shown fast convergence speed, as well as a minimal estimation error. Additionally, we introduce random fluctuations in our analysis to represent changes in the external conditions and which result in poor measurements. The numerical results reveal that both model-free estimators are robust despite the presence of these fluctuations. As a point of reference, we apply the classical Luenberger type observer to our estimation problem and compare the results. Finally, we consider real data of infected individuals in Mexico City, reported from February 2020 to March 2021, and estimate the non-measured populations. Our work's main goal is to proportionate a simple and therefore, an accessible methodology to estimate the behavior of the COVID-19 pandemic from the available data, such that the competent authorities can propose more adequate health politics.

¿Cuál es el punto de corte más significativo de hormona antimülleriana como predictor de la respuesta ovárica, tasa de embarazo y nacido vivo? / What is the most significant cutting point of antimüllerian hormone as a predictor of the ovarian response, pregnancy rate and living born?

Resumen OBJETIVO: Evaluar la eficacia de la hormona antimülleriana en la predicción de la respuesta ovárica, tasa de embarazo y nacido vivo. MATERIALES Y MÉTODOS: Estudio retrospectivo, analítico y observacional efectuado para evaluar los ciclos de estimulación ovárica de pacientes atendidas entre el 1 de enero de 2010 y el 30 de junio de 2017 en el Centro de Reproducción Hisparep. Criterios de inclusión: límites de edad 20 y 44 años y tener ciclos menstruales regulares. Criterios de exclusión: factor masculino alterado, cavidad uterina alterada, trastornos endocrinos, antecedente de daño ovárico. Variables de estudio: concentraciones de hormona antimülleriana, ovocitos recuperados, maduros, fecundados, embriones, tasa de embarazo y nacido vivo. Las variables cuantitativas se analizaron mediante una comparación de medias con t de Student, las variables porcentuales mediante comparación de percentiles. RESULTADOS: Se evaluaron 223 ciclos, divididos en grupos según diferentes puntos de corte. En cualquier punto de corte la hormona antimülleriana predice mayor recuperación de ovocitos maduros y fecundados: 1.25 ng/mL fue el punto de corte más significativo porque predijo mayor obtención de embriones. Se observó relación entre las tasas de embarazo clínico y nacido vivo, aunque su poder predictivo fue débil. Tomar como referencia un punto de corte de 0.5 ng/mL parece predecir bajas probabilidades de nacido vivo. CONCLUSIONES: La hormona antimülleriana fue el mejor marcador de respuesta ovárica; el punto de corte más significativo fue el de 1.25 ng/mL. Hacen falta más estudios para evaluar su eficacia como predictor de bajas tasas de nacido vivo.

Abstract OBJECTIVE: To evaluate the efficacy of antimülleriana hormone in prediction of the ovarian response, pregnancy rate and live birth. MATERIALS AND METHODS: In this retrospective, analytical and observational study, ovarian stimulation cycles were evaluated at the Hisparep Reproduction Center, in a period from January 1, 2010 to June 30, 2017, the inclusion criteria were; Age from 20 to 44 years and regular menstrual cycles. The exclusion criteria; altered male factor, altered uterine cavity, endocrine disorders, antecedent of ovarian damage. The study variables; antimüllerian hormone, oocytes recovered, mature, fertilized, embryos, pregnancy rate and live birth. The quantitative variables were analyzed by means of a comparison of means, using the Student's T test, the percentage variables by means of comparison of percentiles. RESULTS: 223 cycles were evaluated, divided into groups using different cut points. It was determined that Antimullerian Hormone predicts a greater recovery of mature and fertilized oocytes using any cut point, we consider that 1.25 ng / mL was the most significant cutoff point, since it predicts higher embryo obtaining, relationship was observed in pregnancy rates clinical and live birth, although its predictive power is weak, however, using a cutoff of 0.5 ng / mL seems to predict low odds of live birth CONCLUSIONS: Antimullerian hormone is the best marker of ovarian response, we consider that 1.25 ng /mL is the most significant cut-off point, more studies are needed to evaluate its efficacy as a predictor of low rates of live birth.

Angiomiofibroblastoma de la vagina: reporte de un caso y revisión de la literatura / Angyiomyofibroblastoma of the vagina: a case repoprt and literature review

El angiomiofibroblastoma es un tumor mesenquimatoso benigno localizado con mayor frecuencia en la vulva. Este fue descrito por Fletcher y col. en 1992, con el objetivo de distinguirlo del angiomixoma agresivo. Se reporta el caso de una mujer de 49 años de edad, con tumor vaginal pediculado con tallo en fondo de saco vaginal posterior de 6 cm, caracterizado por una proliferación benigna de células ligeramente epitelioides, con numerosos vasos sanguíneos y bien limitada. Por inmunohistoquímica fue positiva para vimentina, desmina, antígeno de músculo específico y receptores estrogénicos. El angiomiofibroblastoma es un tumor casi exclusivo de mujeres (promedio de edad de 42 años) localizado con mayor frecuencia en el área genital, y correspondiendo el 3.6 por ciento a vagina. Es un tumor benigno y que debe de diferenciarse de otras neoplasias de aspecto mixoide que se presentan en esta misma localización.

Leiomiosarcoma primario de la glándula mamaria: reporte de un caso estudiado mediante ultraestructura e inmunohistoquímica / Primary leiomyosarcoma of the breast: a case with electron microscopy and immunohistochemistry

Se informa el caso de un leiomiosarcoma localizado en el cuadrante súpero externo de la glándula mamaria derecha en una mujer de 37 años. El tumor tuvo un crecimiento lento, midió 1.5 cm. de diámetro, era blanco y de consistencia firme. Histológicamente estaba constituido por células fusiform s dispuestas en haces entrecruzados. En las áreas más celulares había de 5 a 6 mitosis por 10 campos a seco fuerte. La inmunohistoquímica fue positiva poara el antígeno muscular específico y en el estudio ultraestructural, las células mostraron miofibrillas y hemodesmosomas. Existen sólo 11 casos publicados de leiomiosarcoma primario de la gándula mamaria cuyas características más importantes son: es más frecuente en mujeres mayores de cincuenta años, es de bajo grado de malignidad y el tratamiento consiste en resección quirúrgica con bordes amplios

La relación médico-paciente durante el trabajo de parto: Determinación de premisas y evaluación: Hospitales Bertha Calderón, Vélez Páiz y Carlos Marx / Doctor-patient relationship through labour: Premises and evaluation determination: Hospitals Berta Calderon, Velez Paiz and Carlos Marx

El presente estudio se planteó como objetivos establecer las premisas que debe poseer la relación médico-paciente durante el trabajo de parto. La primera fase investigativa consistió en la realización de encuestas a médicos de tres hospitales en Managua y encuestas a embarazadas en tercer trimestre de gestación que acudieron a control prenatal en tres centros de salud. En la segunda fase investigativa, se estableció la adecuación de la relación en las salas de emergencia, de labor y expulsivo de los centros hospitalarios durante el período de agosto a septiembre de 1991. El estudio determinó que existe un alto índice de relaciones inadecuadas entre el médico y la mujer durante el parto. Se presentan recomendaciones dirigidas a la introducción de aspectos sociales de la medicina relacionadas de manera específica con las mujeres en estado de gravidez en el plan docente hospitalario de la especialidad de gineco-obstetricia. Además, se recomienda la formación de comités de ética hospitalaria y de supervisión de los aspectos relacionados con el problema