The Problem With National Institute of Standards and Technology Thermodynamics Tables in Continuum Mechanics.

Thermodynamics is a fundamental topic of continuum mechanics and biomechanics, with a wide range of applications to physiological and biological processes. This study addresses two fundamental limitations of current thermodynamic treatments. First, thermodynamics tables distributed online by the U.S. National Institute of Standards and Technology (NIST) report properties of fluids as a function of absolute temperature T and absolute pressure P. These properties include mass density ρ, specific internal energy u, enthalpy h=u+P/ρ, and entropy s. However, formulations of jump conditions across phase boundaries derived from Newton's second law of motion and the first law of thermodynamics employ the gauge pressure p=P-Pr, where Pr is an arbitrarily selected referential absolute pressure. Interchanging p with P is not innocuous as it alters tabulated NIST values for u while keeping h and s unchanged. Using p for functions of state and governing equations solves the problem with using NIST entries for the specific internal energy u in standard thermodynamics tables and analyses of phase transformation in continuum mechanics. Second, constitutive models for the free energy of fluids, such as water and air, are not typically provided in standard thermodynamics treatments. This study proposes a set of constitutive models and validates them against suitably modified NIST data.

Habilitación de funciones frontales básicas en cardiópatas congénitos a través de LEGO® Education / Basic frontal functions qualification in congenital heart disease with LEGO® Education

Las cardiopatías congénitas se consideran una de las anomalías que alteran la irrigación y el intercambio de oxigenación adecuado a las principales venas y arterias. Esto puede generar consecuencias en el desarrollo neurológico que se puede traducir en retraso psicomotor, déficits de aprendizaje, dificultades académicas y problemas de integración social. Para mejorar los trastornos cognitivos, se propone la habilitación cognitiva basada en los principios de mecánica y robótica de LEGO® Education. El objetivo de este estudio fue medir el efecto de un programa de intervención, basado en el uso de ensamblado y programación robótica con LEGO® Education, sobre las funciones frontales básicas como primera aproximación a un modelo propuesto en pacientes cardiópatas congénitos que han sido sometidos a cirugía cardiovascular. Se trató de un estudio de serie de casos, en el que finalizaron el tratamiento una niña y dos niños con cardiopatías congénitas con RACHS 2 y 3. Se aplicaron sub-escalas BANFE-2 y el cuestionario neuropsicológico de daño frontal antes y después del tratamiento; así como una escala para medir el nivel de ejecución por intervención, durante las ocho sesiones. Los resultados muestran en la escala BANFE2, cambios en las medias de las funciones frontales básicas, de daño leve-moderado y normal a normal alto, principalmente en memoria de trabajo y fluidez verbal. En esta primera aproximación, el método LEGO® Education mostró ser una buena herramienta para la habilitación neuropsicológica de estos pacientes.

Congenital heart diseases are considered to be an anomaly which alter the irrigation and the adequate exchange of oxygenation to the main veins and arteries. They can have neurodevelopmental consequences that could translate into psychomotor retardation, learning deficits, academic difficulties, and social integration problems. Cognitive empowerment based on the mechanics and robotics principles of LEGO® Education is proposed to improve cognitive disorders. In this study, the objective was to measure the effect of an intervention program, based on the use of assembly and robotic programming with LEGO® Education, upon basic frontal functions as a first approach to a proposed model in congenital heart disease patients who have undergone cardiovascular surgery. This was a case-series study, in which a girl and two boys with congenital heart disease with RACHS 2 and 3, completed the treatment. BANFE-2 subscales and the neuropsychological questionnaire of frontal damage were applied before and after the treatment; as well as a scale to measure the level of performance per intervention, through all the eight sessions. The BANFE-2 scale showed changes in the means of frontal functions, from mild-moderate damage and normal to high normal, mainly in working memory and verbal fluency. In this first approach, LEGO® Education method proved to be a useful tool for the neuropsychological empowerment of these patients.

Eulerian simulation of complex suspensions and biolocomotion in three dimensions.

We present a numerical method specifically designed for simulating three-dimensional fluid-structure interaction (FSI) problems based on the reference map technique (RMT). The RMT is a fully Eulerian FSI numerical method that allows fluids and large-deformation elastic solids to be represented on a single fixed computational grid. This eliminates the need for meshing complex geometries typical in other FSI approaches and greatly simplifies the coupling between fluid and solids. We develop a three-dimensional implementation of the RMT, parallelized using the distributed memory paradigm, to simulate incompressible FSI with neo-Hookean solids. As part of our method, we develop a field extrapolation scheme that works efficiently in parallel. Through representative examples, we demonstrate the method's suitability in investigating many-body and active systems, as well as its accuracy and convergence. The examples include settling of a mixture of heavy and buoyant soft ellipsoids, lid-driven cavity flow containing a soft sphere, and swimmers actuated via active stress.

Resección laparoendoscópica de tumor de la unión gastroesofágica / Laparoendoscopic resection of a tumor of the gastroesophageal junction

RESUMEN La resección gástrica atípica ha demostrado ser beneficiosa para tumores submucosos. La técnica pre senta mayor riesgo cuando estos se desarrollan próximos a la unión esófago-gástrica (UEG). Para esta limitación se propuso la resección intragástrica mediante una técnica mixta combinando laparoscopia y endoscopia. En nuestro medio no existen publicaciones al respecto. Se trata de una mujer de 42 años, con lesión subepitelial-subcardial de 2 cm, evaluada mediante videoendoscopia alta (VEDA), compa tible con tumor del estroma gastrointestinal (GIST) evaluado mediante ecoendoscopia. La lesión fue resecada mediante abordaje combinado laparoendoscópico. Bajo visión laparoscópica se introdujeron en cavidad abdominal trocares con balón, y bajo visión endoscópica intragástrica se introdujeron estos en el estómago y se fijó la pared gástrica a la pared abdominal insuflando dichos balones. Posterior mente se realizó la resección de la lesión con sutura mecánica. El abordaje combinado es seguro y eficaz, simple en manos entrenadas, pero constituye una opción reproducible en casos seleccionados.

ABSTRACT Atypical gastric resection has proved to be beneficial to treat submucosal tumors. The technique is more difficult when these tumors develop next to the gastroesophageal junction (GEJ). Intragastric resection combining endoscopic and laparoscopic approach was proposed to solve this limitation. There are no publications about this technique in our environment. A 42-year-old female patients with a 2-mm subepithelial tumor below the cardia evaluated by upper gastrointestinal (UGI) videoendoscopy and endoscopic ultrasound suggestive of a gastrointestinal stroma tumor (GIST) underwent resection using the combined laparo-endoscopic approach. Under laparoscopic guidance, balloon-tipped trocars were introduced in the abdominal cavity and then into the stomach using endoscopic view. The balloons were inflated to fix the gastirc wall to the abdominal wall. The lesion was resected using mechanical stapler. The combined approach is safe and efficient, and simple to perform for trained professionals, constituting a reproducible option in selected cases.

Sensory studies, or when physics was psychophysics: Ernst Mach and physics between physiology and psychology, 1860-71.

This paper highlights the significance of sensory studies and psychophysical investigations of the relations between psychic and physical phenomena for our understanding of the development of the physics discipline, by examining aspects of research on sense perception, physiology, esthetics, and psychology in the work of Gustav Theodor Fechner, Hermann von Helmholtz, Wilhelm Wundt, and Ernst Mach between 1860 and 1871. It complements previous approaches oriented around research on vision, Fechner's psychophysics, or the founding of experimental psychology, by charting Mach's engagement with psychophysical experiments in particular. Examining Mach's study of the senses and esthetics, his changing attitudes toward the mechanical worldview and atomism, and his articulation of comparative understandings of sensual, geometrical, and physical spaces helps set Mach's emerging epistemological views in the context of his teaching and research. Mach complemented an analytic strategy focused on parallel psychic and physical dimensions of sensation, with a synthetic comparative approach - building analogies between the retina, the individual, and social life, and moving between abstract and sensual spaces. An examination of the broadly based critique that Mach articulated in his 1871 lecture on the conservation of work shows how his historical approach helped Mach cast what he now saw as a narrowly limiting emphasis on mechanics as a phase yet to be overcome.

Meta-analysis as a system of springs.

Meta-analysis results are usually presented in forest plots, which show the individual study results and the summary effect along with their confidence intervals. In this paper, we propose a system of linear springs as a mechanical analogue of meta-analysis that enables visualization and enhances intuition. The length of a spring corresponds to a study treatment effect and the stiffness of the spring corresponds to its inverse variance. To synthesize study springs we use two main operations: connection in parallel and connection in series. We show the equivalence between meta-analysis and linear springs for fixed effect and random effects pairwise meta-analysis and we also derive indirect treatment effects. We use examples to illustrate the different meta-analytical schemes using the corresponding system of springs. The proposed visualization can serve as an educational tool, especially useful for researchers with no statistical background. The analogy between meta-analysis and springs facilitates intuition for notions such as heterogeneity and the differences between fixed and random effects meta-analysis.

Fisiología respiratoria mecánica de la respiración / Mechanics breathing

El trabajo respiratorio se ejerce en una estructura cerrada donde se encuentran los pulmones, estos son sometidos a cambios de presiones determinados por la musculatura pulmonar en las diferentes fases del ciclo respiratorio, lo que generará gradientes y permite la entrada y salida de aire. Se suman a ello el calibre de las vías aéreas, el tipo de flujo, las características de las vías aéreas y del surfactante pulmonar, que determinan un menor o mayor trabajo respiratorio según la condición fisiológica.

The work of breathing is exerted in a closed structure where the lungs are located. These are subjected to pressure changes determined by the pulmonary musculature in the different phases of the respiratory cycle, which will generate gradients and allow the entry and exit of air. In addition to the aforesaid, airway calibre, type of flow, airway characteristics and pulmonary surfactant determine less or more work of breathing depending on the physiological condition.

Tratamiento de la coledocolitiasis mediante CPRE e instrumentación a través de un tubo en T / Treatment of choledocholithiasis by ERCP, and instrumentation through a T-tube

Resumen El tratamiento de la coledocolitiasis ha evolucionado de forma significativa desde que Robert Abbe realizó la primera coledocotomía y la exploración de las vías biliares en Nueva York, en 1889. La colangiopancreatografía retrógrada endoscópica (CPRE), que inicialmente fue un método diagnóstico, ahora solo tiene validez como método terapéutico. En la actualidad, los principales métodos diagnósticos son la colangioresonancia magnética (CRM) y la ultrasonografía endoscópica (USE). El tratamiento de la coledocolitiasis pasó de la técnica quirúrgica abierta -en la que, de forma rutinaria, se realizaba la coledocorrafia sobre un tubo de Kehr o tubo en T- a la endoscópica, mediante el uso de la CPRE, la esfinteroplastia y la instrumentación con balones y canastilla. Hoy en día se dispone de técnicas adicionales como la litotricia mecánica (LM) o extracorpórea, la dilatación con balón (DB) de gran tamaño y el Spyglass ® . La técnica laparoscópica se usa desde hace varios años, en diversas partes del mundo, para el tratamiento de la coledocolitiasis. Estudios recientes proponen incluso el cierre primario del colédoco o la coledocoduodenostomía, con lo cual no sería necesaria la utilización del tubo en T. Pero en muchos otros sitios, y por diversas razones, se continúa usando la exploración quirúrgica abierta y el tubo en T, que representa una importante opción en el tratamiento de algunos pacientes. Caso clínico: paciente masculino de 88 años, con coledocolitiasis recidivante, cálculo gigante de difícil manejo endoscópico y sepsis de origen biliar, que requirió drenaje quirúrgico abierto de urgencias. Se realizó una coledocotomía, y se dejó el tubo en T. Posteriormente, se efectuó un tratamiento exitoso conjunto, mediante instrumentación por el tubo en T, por parte de cirugía general, y CPRE, por gastroenterología.

Abstract The treatment of choledocholithiasis has evolved significantly since Robert Abbé performed the first bile duct exploration via choledochotomy in New York in 1889. Endoscopic retrograde cholangiopancreatography (ERCP), which was initially used for diagnosis, is now only valid as a therapeutic tool. Currently, the main diagnostic methods are magnetic resonance cholangiopancreatography (MRCP) and endoscopic ultrasound (EUS). The treatment of choledocholithiasis moved from the open surgery in which biliary stenting was routinely performed on a Kehr tube or T-tube, to the endoscopic technique using ERCP, sphincteroplasty and instrumentation with balloons and baskets. Additional techniques are now available such as mechanical or extra-corporeal lithotripsy, endoscopic papillary large balloon dilation and SpyGlass cholangioscopy. The laparoscopic technique has been used for several years in different parts of the world for the treatment of choledocholithiasis. Recent studies even propose performing the primary closure of the bile duct or choledochoduodenostomy, so that the T-tube is not necessary. However, in many other places, and for a variety of reasons, open exploratory surgery and the T-tube continue to be used, being an important option in the treatment of some patients. Case presentation: 88-year-old male patient with recurrent choledocholithiasis and a giant gallstone that was difficult to treat endoscopically, with sepsis of biliary origin, which required open surgical drainage at the emergency room. Choledocotomy was performed, and a T-tube was inserted at the site. Subsequently, a successful joint treatment was performed by the General Surgery Service and the Gastroenterology Service, using T-tube instrumentation and ERCP, respectively.