Palabras que calan: la escritura de Julio Torri

Entre la diversidad de opiniones sobre la obra de Julio Torri destacan como características principales y muy relacionadas entre sí la brevedad, la mezcla de géneros, el humor, la ironía, lo fantástico, la calidad literaria y el esteticismo de su prosa, el estilo pulcro y perfecto de su escritura, su preferencia por la prosa (así se llame poética), su exigencia y rigor ante lo que escribe, la innegable relación de sus textos con otros de diferentes culturas y autores; pero, a nuestro juicio, lo sobresaliente es la apreciación que se tiene sobre la originalidad y actualidad de la obra de Julio Torri

ONLINE PARAMETRIC IDENTIFICATION OF MASS-SPRING-DAMPER MECHANICAL SYSTEMS USING ACCELERATION MEASUREMENTS

AbstractImplementation of active vibration control schemes, failure detection and monitoring tasks of the suitable operation of flexible mechanical structures can require the use of on-line parametric identification techniques. Measurements of acceleration signals are preferred in several applications of parameter identification of vibrating mechanical systems. In this article, an on-line parameter estimation approach in time domain is proposed for linear mass-spring-damper mechanical systems of n degrees of freedom using acceleration measurements solely. Integration by parts is properly used in the synthesis of the proposed parameter identification method. In this fashion, a priori knowledge of the initial conditions of the system becomes unnecessary. The introduced identification method can be extended for real-time parametric estimation of nonlinear fully actuated or under-actuated nonlinear vibrating mechanical systems. Some numerical results are provided to show the effectiveness of the on-line estimation approach of the mass, stiffness and damping parameters combined with closed-loop reference trajectory tracking tasks specified for the vibrating mechanical system.Keywords: Active vibration control, mass-spring-damper systems, mechanical vibration systems, parameter identification.IDENTIFICACIÓN PARAMÉTRICA EN LÍNEA DE SISTEMAS MECÁNICOS DE MASA-RESORTE-AMORTIGUADOR UTILIZANDO MEDICIONES DE ACELERACIÓNResumenImplementación de esquemas de control activo de vibraciones, detección de fallas o tareas de monitoreo de la operación adecuada de estructuras mecánicas flexibles pueden requerir el uso de técnicas de identificación paramétrica ejecutadas en línea. Mediciones de señales de aceleración se usan en varias aplicaciones de identificación de parámetros en sistemas mecánicos vibratorios. En este artículo se propone un enfoque para estimación de parámetros en línea en el dominio del tiempo para sistemas mecánicos del tipo masa-resorte-amortiguador de n grados de libertad, usando únicamente mediciones de aceleración. Se usa integración por partes en la síntesis del método de identificación de parámetros propuesto. De esta manera, conocimiento previo de las condiciones iniciales del sistema son innecesarias. El método de estimación propuesto se puede extender para estimación paramétrica en tiempo real para sistemas mecánicos vibratorios no lineales, completamente actuados o sub-actuados. Se incluyen algunos resultados de simulación numérica para mostrar la efectividad del enfoque de estimación de parámetros de masa, rigidez y amortiguamiento, combinado con tareas de seguimiento de trayectorias de referencia en lazo-cerrado especificadas para el sistema mecánico vibratorio.Palabras Claves: control activo de vibraciones, identificación de parámetros, sistemas mecánicos vibratorios, sistemas masa-resorte-amortiguador

Cerebral embolization associated with parenchymal seeding of the left atrial myxoma : Potential role of interleukin-6 and matrix metalloproteinases

Systemic embolization has been reported in up to 40% of patients with left atrial myxoma, half of them with cerebral involvement. However, development of intracerebral embolization associated with parenchymal seeding of the myxoma emboli is an extremely rare complication, with only 36 histologically diagnosed cases reported in the published literature. We describe a 69-year-old woman who arrived at the emergency service with hemiparesis associated with drug-resistant epilepsy and a medical history of resection of a left atrial myxoma 10 months previously. Cranial computed tomography revealed multiple large lesions of heterogeneous density and cystic components in the occipital lobes and posterior fossa parenchyma. Histopathological analyses after stereotactic biopsy of the occipital lesion revealed infiltrative myxoma cells with benign histological findings and uniform expression of calretinin similar to that of the primary cardiac myxoma. Additional immunohistochemical studies confirmed brain parenchymal seeding of the myxoma cells with strong expression of interleukin-6 (IL-6) and focal expression of matrix metalloproteinases-2 (MMP-2). Here, we discuss the clinicopathological features of intracerebral embolization of left atrial myxomas associated with progressive parenchymal seeding of the tumor emboli and the potential pathogenic role of IL-6 and MMPs.Peer reviewe

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Background: Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. // Methods: We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung's disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. // Findings: We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung's disease) from 264 hospitals (89 in high-income countries, 166 in middle-income countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in low-income countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. // Interpretation: Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between low-income, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030