A digital twin-based optimization procedure is presented for an ultraprecision motion system with a flexible shaft connecting the motor to the (elastic) load, which is subject to both backlash and ...friction. The main contributions of the study are the design of the digital twin and its implementation, assuming a two-mass drive system. The procedure includes the virtual representation of mechanical and electrical components, non-linearities (backlash and friction), and the corresponding control system. A procedure for digital twin-based optimization is also presented, in which the maximum absolute position error is minimized while maintaining accuracy with no significant increase in the control effort. The optimal settings for the controller parameters and for the backlash peak amplitude, the backlash peak time, and the hysteresis amplitude are then determined, in order to guarantee an appropriate dynamic response in the presence of backlash and friction. The surface quality of certain manufactured components, such as hip and knee implants, depends on the smoothness and the accuracy of the real trajectory produced in the cutting process that is strongly influenced by the maximum position error. The simulations and experimental studies are presented using a real platform and two references for trajectory control, and a comparison of four digital twin-based optimization methods. The simulation study and the real-time experiments demonstrate the suitability of the digital twin-based optimization procedure and lay the foundations for the implementation of the proposed method at an industrial level.
AKI in coronavirus disease 2019 (COVID-19) is associated with higher morbidity and mortality. The objective of this study was to identify the kidney histopathologic characteristics of deceased ...patients with diagnosis of COVID-19 and evaluate the association between biopsy findings and clinical variables, including AKI severity.
Our multicenter, observational study of deceased patients with COVID-19 in three third-level centers in Mexico City evaluated postmortem kidney biopsy by light and electron microscopy analysis in all cases. Descriptive and association statistics were performed between the clinical and histologic variables.
A total of 85 patients were included. Median age was 57 (49-66) years, 69% were men, body mass index was 29 (26-35) kg/m
, 51% had history of diabetes, 46% had history of hypertension, 98% received anticoagulation, 66% were on steroids, and 35% received at least one potential nephrotoxic medication. Severe AKI was present in 54% of patients. Biopsy findings included FSGS in 29%, diabetic nephropathy in 27%, and arteriosclerosis in 81%. Acute tubular injury grades 2-3 were observed in 49%. Histopathologic characteristics were not associated with severe AKI; however, pigment casts on the biopsy were associated with significantly lower probability of kidney function recovery (odds ratio, 0.07; 95% confidence interval, 0.01 to 0.77). The use of aminoglycosides/colistin, levels of C-reactive protein and serum albumin, previous use of angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers, antivirals, nonsteroid anti-inflammatory drugs, and anticoagulants were associated with specific histopathologic findings.
A high prevalence of chronic comorbidities was found on kidney biopsies. Nonrecovery from severe AKI was associated with the presence of pigmented casts. Inflammatory markers and medications were associated with specific histopathologic findings in patients dying from COVID-19.
RESUMEN La coartación aórtica representa el 5-8% de todas las cardiopatías congénitas y se define como un estrechamiento de la luz aórtica a nivel del ligamento arterioso o debajo de este, ...clasificándose en preductal o posductal, y existen varias teorías que tratan de explicar su etiología, que aún sigue siendo poco clara. Puede diagnosticarse desde la infancia o en la edad adulta, debe sospecharse en todo paciente antes de los 30 años de edad que presente hipertensión arterial sistémica para poder brindar un tratamiento quirúrgico oportuno.
Heart failure is highly prevalent among patients >65 years old. The incidence increases starting at ∼45 years of age. Recent therapeutic advances have included stem cell transplantation in the ...affected areas of the myocardium in order to improve perfusion and myocardial performance.
Between July 13, 2004 and August 31, 2005, 39 procedures were undertaken in 34 male and 5 female patients, with a mean age of 53.6 ± 9.08 years (range: 35–71 years old), suffering from terminal heart failure and without any other therapeutic alternative. Thirty four cases presented ischemic cardiomyopathy and five presented idiopathic dilated cardiomyopathy. All patients were treated with autologous stem cell transplantation obtained from the peripheral blood supply through hemophoresis and implanted by means of a left anterior thoracotomy via intramyocardial injection. Functional class, ejection fraction and myocardial perfusion were analyzed preoperatively and postoperatively.
Seven patients presented ventricular fibrillation during the procedure, requiring defibrillation. Two patients died due to intractable arrhythmias during the perioperative period; the remaining patients are currently participating in a rehabilitation program with a favorable evolution. A mid-term follow-up has been completed in 27 patients. Preoperatively, the functional class for 26 of these patients was III. Postoperatively, functional classes are II in 5 cases and I in 15 patients at the mid-term evaluation with ejection fraction improvements of 37.7 ± 14.2 to 42.15 ± 5.9.
Cell therapy is a safe and useful procedure in selected patients with ischemic and idiopathic dilated cardiomyopathy.
El síndrome aórtico agudo incluye al hematoma intramural, la úlcera aterosclerótica penetrante y la disección aórtica. Esta última se caracteriza por un desgarro en la íntima de la aorta, que expone ...la capa media, permitiendo la entrada al flujo sanguíneo pulsátil, disecándola y extendiéndose longitudinalmente, lo que crea una luz falsa y un flap intimal, pudiendo complicarse con ruptura aórtica, taponamiento cardiaco, insuficiencia cardíaca y muerte súbita. Se reporta el caso de un paciente, en el cual, gracias al ecocardiograma transesofágico se pudo llegar a un diagnóstico rápido y brindar un tratamiento urgente y sin complicaciones.
La arteria coronaria única es una anomalía congénita en la que el árbol coronario nace de un solo ostium, pudiendo asociarse a otras malformaciones cardíacas. Puede ser un hallazgo incidental, sin ...embargo, en pacientes jóvenes, o en casos de cursar con un trayecto interarterial, puede ser causa de angina, infarto agudo del miocardio e incluso muerte súbita, siendo de vital importancia su oportuna identificación. Se presenta el caso de un paciente el cual presentó dolor precordial, diagnosticando infarto agudo del miocardio sin elevación del ST, identificándose en angiografía y angiotoTC coronaria esta inusual anomalía.
The pulmonary valve’s anomalies can lead to the obstruction of the right ventricle’s outflow tract. This leads to the right ventricle’s pressure overload, dilation, hypertrophy and eventually his ...malfunction. Balloon angioplasty or valve replacement surgery is indicated in cases of severe pulmonary stenosis. Often, the insertion of bioprosthetic pulmonary valves is required; however, after several years these patients often require a second surgery due to the valve’s malcfunction. We report the case of a pregnant patient with a bioprosthetic pulmonary valve who required a ballon angioplasty due to this valve’s stenosis.
El corazón univentricular es una rara cardiopatía congénita cianógena compleja, caracterizada por la presencia de una sola cavidad ventricular en la que drenan ambas aurículas, pudiendo presentarse ...de 3 formas morfológicas distintas. Es causado por ausencia en la formación del tabique interventricular, produciendo un corazón con tres cavidades. Tiene una prevalencia de 5 de cada 100, 000 nacidos vivos, de predominio en el sexo masculino, constituyendo un 2% del total de las cardiopatías congénitas. Dependiendo las alteraciones acompañantes se manifiesta clínicamente por cianosis, hipertensión pulmonar e insuficiencia cardíaca congestiva. Suele asociarse a alteraciones en la posición de las grandes arterias, dextrocardia, estenosis valvular o subvalvular pulmonar, estenosis subaórtica, drenaje venoso pulmonar anómalo total o parcial, coartación aórtica y bloqueo AV congénito. El diagnóstico se puede realizar desde el período prenatal mediante la ecografía fetal, lo que puede mejorar la supervivencia al realizar un manejo temprano principalmente quirúrgico.
Los betabloqueantes tópicos para el tratamiento del glaucoma tienen una mayor absorción por el sistema vascular conjuntival a diferencia de lo que se pensaba, ya que evitan el metabolismo hepático, ...pudiendo llegar a provocar efectos sistémicos adversos como trastornos del sistema de conducción, los cuales son más frecuentes en pacientes con trastornos cardíacos y de edad avanzada, por lo que ante todo paciente con evidencia de trastornos de la conducción y antecedente de glaucoma, se debe interrogar intencionadamente sobre el uso de fármacos betabloqueantes como el timol, ya que muchas veces este no es considerado parte de su tratamiento, al administrarse de manera tópica. Presentamos el caso de una paciente de 62 años de edad con antecedente de uso crónico de timolol en gotas oftálmicas, la cual presentó bloqueo auriculoventricular de tercer grado, ameritando colocación de marcapasos definitivo.
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