Recursive identification and tracking of parameters for linear and nonlinear multivariable systems

The problem of identifying constant and variable parameters in multi-input, multi-output, linear and nonlinear systems is considered, using the maximum likelihood approach. An iterative algorithm, leading to recursive identification and tracking of the unknown parameters and the noise covariance matrix, is developed. Agile tracking, and accurate and unbiased identified parameters are obtained. Necessary conditions for a globally, asymptotically stable identification process are provided; the conditions proved to be useful and efficient. Among different cases studied, the stability derivatives of an aircraft were identified and some of the results are shown as examples

An adaptive tracking observer for failure-detection systems

The design problem of adaptive observers applied to linear, constant and variable parameters, multi-input, multi-output systems, is considered. It is shown that, in order to keep the observer's (or Kalman filter) false-alarm rate (FAR) under a certain specified value, it is necessary to have an acceptable proper matching between the observer (or KF) model and the system parameters. An adaptive observer algorithm is introduced in order to maintain desired system-observer model matching, despite initial mismatching and/or system parameter variations. Only a properly designed adaptive observer is able to detect abrupt changes in the system (actuator, sensor failures, etc.) with adequate reliability and FAR. Conditions for convergence for the adaptive process were obtained, leading to a simple adaptive law (algorithm) with the possibility of an a priori choice of fixed adaptive gains. Simulation results show good tracking performance with small observer output errors and accurate and fast parameter identification, in both deterministic and stochastic cases

On the feasibility of real-time prediction of aircraft carrier motion at sea

The ability to predict the aircraft carrier's motion over an interval of several seconds within reasonable error bounds may allow an improvement in touchdown dispersion and a more certain value for ramp clearance due to a smoother aircraft trajectory. Also, improved information to the landing signal officer should decrease the number of waveoffs substantially. It is quantitatively shown that, based on the power density spectrum data for pitch and heave measured for various ships and sea conditions, the motion can be predicted well for up to 15 seconds. The zero crossover times for both pitch and heave motions can be predicted with impressive accuracy. The predictor was designed on the basis of Kalman's optimum filtering theory for the discrete time case, adapted for real-time digital computer operation

CD103 (αE Integrin) Undergoes Endosomal Trafficking in Human Dendritic Cells, but Does Not Mediate Epithelial Adhesion

Dendritic cell (DC) expression of CD103, the α subunit of αEβ7 integrin, is thought to enable DC interactions with E-cadherin-expressing gastrointestinal epithelia for improved mucosal immunosurveillance. In the stomach, efficient DC surveillance of the epithelial barrier is crucial for the induction of immune responses to H. pylori, the causative agent of peptic ulcers and gastric cancer. However, gastric DCs express only low levels of surface CD103, as we previously showed. We here tested the hypothesis that intracellular pools of CD103 in human gastric DCs can be redistributed to the cell surface for engagement of epithelial cell-expressed E-cadherin to promote DC-epithelial cell adhesion. In support of our hypothesis, immunofluorescence analysis of tissue sections showed that CD103+ gastric DCs were preferentially localized within the gastric epithelial layer. Flow cytometry and imaging cytometry revealed that human gastric DCs expressed intracellular CD103, corroborating our previous findings in monocyte-derived DCs (MoDCs). Using confocal microscopy, we show that CD103 was present in endosomal compartments, where CD103 partially co-localized with clathrin, early endosome antigen-1 and Rab11, suggesting that CD103 undergoes endosomal trafficking similar to β1 integrins. Dynamic expression of CD103 on human MoDCs was confirmed by internalization assay. To analyze whether DC-expressed CD103 promotes adhesion to E-cadherin, we performed adhesion and spreading assays on E-cadherin-coated glass slides. In MoDCs generated in the presence of retinoic acid, which express increased CD103, intracellular CD103 significantly redistributed toward the E-cadherin-coated glass surface. However, DCs spreading and adhesion did not differ between E-cadherin-coated slides and slides coated with serum alone. In adhesion assays using E-cadherin-positive HT-29 cells, DC binding was significantly improved by addition of Mn2+ and decreased in the presence of EGTA, consistent with the dependence of integrin-based interactions on divalent cations. However, retinoic acid failed to increase DC adhesion, and a CD103 neutralizing antibody was unable to inhibit DC binding to the E-cadherin positive cells. In contrast, a blocking antibody to DC-expressed E-cadherin significantly reduced DC binding to the epithelium. Overall, these data indicate that CD103 engages in DC-epithelial cell interactions upon contact with epithelial E-cadherin, but is not a major driver of DC adhesion to gastrointestinal epithelia

Abstracts from the 20th International Symposium on Signal Transduction at the Blood-Brain Barriers

https://deepblue.lib.umich.edu/bitstream/2027.42/138963/1/12987_2017_Article_71.pd

Factores de riesgo en pacientes con pie diabético

Uno de los principales problemas de salud en todo el mundo es la diabetes. Cada vez son más las personas que padecen de esta enfermedad. Las cifras estiman que para 1980 unos 108 millones de personas la padecían, ésta cifra se incrementó drásticamente para el 2014, donde el número de diabéticos ascendió a 422 millones. El pie diabético es una de las enfermedades más serias y de mayores complicaciones relacionada con miembros pélvicos, de todas las enfermedades provenientes de la diabetes. El objetivo del presente estudio se centra en plasmar los factores de riesgo que predisponen la aparición del pie diabético, los cuales constituyen uno de los pilares elementales en la prevención y erradicación de esta complicación tan importante de la diabetes. Para su desarrollo se llevó a cabo una revisión de material documental bibliográfico actualizado. Los principales factores de riesgo para desarrollar pie diabético son la presencia de neuropatía diabética, el tabaquismo, diabetes de más de diez años en desarrollo y falta de información y motivación para el autocuidado. Por último, se concluye que es vital, las instrucciones básicas de autocuidado que cada paciente y su familia puedan recibir, ya que esto constituye la primera línea en la prevención contra las complicaciones de la diabetes. Asimismo, es imperioso en cada centro de salud organizar programas educativos que faciliten un seguimiento al paciente, con la finalidad de que el este reciba un proceso continuo, que le permita a su vez llevar a cabo adecuadamente las tareas de autocuidado.

Diabetes mellitus in chronic kidney disease: Biomarkers beyond HbA1c to estimate glycemic control and diabetes-dependent morbidity and mortality

Diabetes mellitus (DM) is the leading cause of chronic kidney disease (CKD). Optimal glycemic control contributes to improved outcomes in patients with DM, particularly for microvascular damage, but blood glucose levels are too variable to provide an accurate assessment and instead markers averaging long-term glycemic load are used. The most established glycemic biomarker of long-term glycemic control is HbA1c. Nevertheless, HbA1c has pitfalls that limit its accuracy to estimate glycemic control, including the presence of altered red blood cell survival, hemoglobin glycation and suboptimal performance of HbA1c assays. Alternative methods to evaluate glycemic control in patients with DM include glycated albumin, fructosamine, 1–5 anhydroglucitol, continuous glucose measurement, self-monitoring of blood glucose and random blood glucose concentration measurements. Accordingly, our aim was to review the advantages and pitfalls of these methods in the context of CKD

Factores de riesgo de obesidad en empleados públicos

La obesidad representa una patología de orden multifactorial, en la misma influyen diferentes factores, los cuales llevan a que sea considerada un problema de salud público. Se basa en un trastorno complejo que consiste en tener una cantidad excesiva de grasa corporal, aumentando el riesgo de enfermedades y problemas de salud, tales como enfermedad cardíaca, diabetes y presión arterial alta. Según investigaciones esta patología, representa una condición patológica muy común en el ser humano y presente desde la remota antigüedad, que persiste y se incrementa durante siglos por factores genéticos y ambientales, hasta convertirse actualmente en una pandemia con consecuencias nefastas para la salud. En base a esto, se destaca la importancia y objetivo general del presente estudio, el cual centra su atención en analizar los factores de riesgo de obesidad en empleados públicos. La metodología aplicada fue de tipo documental, pues en él se realiza un análisis de contenido de artículos y documentos sobre el tema y en bases de datos. Entre sus resultados se encontró que: la obesidad representa una condición médica en la que influyen los estilos de vida, hábitos alimenticios, sedentarismo, estrés asociado con grados de ansiedad, originados por exceso de trabajo; condiciones éstas que conllevan al individuos a consumir una dieta alta en grasas y azúcares, lo que en consecuencia origina incluso, altos grados de dislipidemias y otras consecuencias médicas propias de enfermedades crónicas no transmisibles como es el caso de la diabetes, hipertensión, enfermedades cerebrovasculares. En consecuencia, se debe resaltar que la acción clave para controlar esta epidemia, que afecta a todos los estratos sociales de la población, es prevenir. Dentro de los factores de riesgo más comunes se encuentran el desequilibrio de energía, inactividad física, genética, factores emocionales, hábito de fumar, embarazo y pérdida del sueño

Antigen recognition detains CD8+ T cells at the blood-brain barrier and contributes to its breakdown

Abstract Blood-brain barrier (BBB) breakdown and immune cell infiltration into the central nervous system (CNS) are early hallmarks of multiple sclerosis (MS). High numbers of CD8+ T cells are found in MS lesions, and antigen (Ag) presentation at the BBB has been proposed to promote CD8+ T cell entry into the CNS. Here, we show that brain endothelial cells process and cross-present Ag, leading to effector CD8+ T cell differentiation. Under physiological flow in vitro, endothelial Ag presentation prevented CD8+ T cell crawling and diapedesis resulting in brain endothelial cell apoptosis and BBB breakdown. Brain endothelial Ag presentation in vivo was limited due to Ag uptake by CNS-resident macrophages but still reduced motility of Ag-specific CD8+ T cells within CNS microvessels. MHC class I-restricted Ag presentation at the BBB during neuroinflammation thus prohibits CD8+ T cell entry into the CNS and triggers CD8+ T cell-mediated focal BBB breakdown