A phenomenological computational model of the evoked action potential fitted to human cochlear implant responses.

There is a growing interest in biomedical engineering in developing procedures that provide accurate simulations of the neural response to electrical stimulus produced by implants. Moreover, recent research focuses on models that take into account individual patient characteristics. We present a phenomenological computational model that is customized with the patient's data provided by the electrically evoked compound action potential (ECAP) for simulating the neural response to electrical stimulus produced by the electrodes of cochlear implants (CIs). The model links the input currents of the electrodes to the simulated ECAP. Potentials and currents are calculated by solving the quasi-static approximation of the Maxwell equations with the finite element method (FEM). In ECAPs recording, an active electrode generates a current that elicits action potentials in the surrounding auditory nerve fibers (ANFs). The sum of these action potentials is registered by other nearby electrode. Our computational model emulates this phenomenon introducing a set of line current sources replacing the ANFs by a set of virtual neurons (VNs). To fit the ECAP amplitudes we assign a suitable weight to each VN related with the probability of an ANF to be excited. This probability is expressed by a cumulative beta distribution parameterized by two shape parameters that are calculated by means of a differential evolution algorithm (DE). Being the weights function of the current density, any change in the design of the CI affecting the current density produces changes in the weights and, therefore, in the simulated ECAP, which confers to our model a predictive capacity. The results of the validation with ECAP data from two patients are presented, achieving a satisfactory fit of the experimental data with those provided by the proposed computational model.

Eritrocitosis secundaria a cardiopatía congénita como causa de pseudohipercalemia / Secundary erithrocitosis from congenital heart disease as a cause of pseudohiperkalemia

Resumen El potasio es, sin lugar a duda, uno de los componentes más importantes del balance hidroelectrolítico, además de ser uno de los exámenes de laboratorio más solicitados en el ámbito clínico. La hipercalemia se define por un valor sérico mayor a 5.5 mEq/L y su principal diagnóstico diferencial es la pseudohipercalemia o hipercalemia espuria. Esta se define como elevación del potasio solo en componente sérico y no plasmático con una diferencia mínima de 0.5 mEq/L. Entre las causas de pseudohipercalemia se encuentran factores mecánicos, químicos, contaminantes, temperatura y tiempo de procesamiento de la muestra. Se reporta el caso de un paciente masculino de 22 años de edad, con antecedentes de cardiopatía cianosante, que cursa con elevación espuria de potasio en suero, con aumento aislado severo del hematocrito y trombocitopenia concomitante, que luego mostraría valores normales en plasma.

Abstract Potassium is, without a doubt, one of the most important components of hydroelectrolitic balance, as well as being one of the most requested laboratory exams in the clinical setting. Hyperkalemia is defined as serum value above 5.5 mEq/L, and its main differential diagnosis is pseudohyperkalemia or spurious hyperkalemia. This conditioned is defined as an elevation of potassium levels exclusively in serum and not in plasma, with a minimal difference of 0.5 mEq/L between these measurements. Some of the causes of pseudohyperkalemia include mechanical factors, chemicals, contaminants, temperature and the time of sample processing. It is reported the case of a 22-year-old male with history of cyanotic heart disease that presented with a spurious elevation of serum potassium, with a severe increment in hematocrit and concomitant thrombocytopenia, that would later show normal levels in plasma.

Marangoni puffs: dramatically enhanced dissolution of droplets with an entrapped bubble.

We present a curious effect observed during the dissolution process of water-immersed long-chain alcohol drops with an entrapped air bubble. These droplets dissolve while entrapping an air bubble pinned at the substrate. We qualitatively describe and explain four different phases that are found during the dissolution of this kind of system. The dissolution rate in the four phases differ dramatically. When the drop-water interface and the air bubble contact each other, rapid cyclic changes of the morphology are found: The breakage of the thin alcohol layer in between the bubble and the water leads to the formation of a three phase contact line. If the surface tension of the water-air interface supersedes those of the alcohol-water and alcohol-air interfaces, alcohol from the droplet is pulled upwards, leading to a closure of the air-water interface and the formation of a new thin alcohol film, which then dissolves again, leading to a repetition of the series of events. We call this sequence of events Marangoni puffing. This only happen for alcohols of appropriate surface tension. The Marangoni puffing is an intermediate state. In the final dissolution phases the Marangoni forces dramatically accelerate the dissolution rate, which then becomes one order of magnitude faster than the purely buoyancy-convective driven dissolution. Our results have bearing on various dissolution processes in multicomponent droplet systems.

The Posterior Lumbar Epidural Space: Three-Dimensional Reconstruction of High-Resolution MRI: Real and Potential Epidural Spaces and Their Content In Vivo.

OBJECTIVE: Our aim was to study the posterior lumbar epidural space with 3D reconstructions of magnetic resonance images (MRIs) and to compare and validate the findings with targeted anatomic microdissections. DESIGN: We performed 3D reconstructions of high-resolution MRIs from seven patients and normal-resolution MRIs commonly used in clinical practice from 196 other random patients. We then dissected and photographed the lumbar spine areas of four fresh cadavers. RESULTS: From the 3D reconstructions of the MRIs, we verified that the distribution of the posterior fat pad had an irregular shape that resembled a truncated pyramid. It spanned between the superior margin of the lamina of the caudad vertebra and beyond the inferior margin to almost halfway underneath the cephalad lamina of the cranial vertebra, and it was not longitudinally or circumferentially continuous. The 3D reconstructions of the high-definition MRI also consistently revealed a prelaminar fibrous body that was not seen in most of the usually used low-definition MRI reconstructions. Targeted microdissections confirmed the 3D reconstruction findings and also showed the prelaminar tissue body to be fibrous, crossing from side to side anterior to the cephalad half of each lamina, and spanning from the dural sac to the laminae. CONCLUSIONS: Three-dimensional reconstructions and targeted microdissection revealed the unique appearance of posterior fat pads and a prelaminar fibrous body. The exact consistency, presence, prevalence with age, presence in other regions, and function of this body are unknown and require further research.

Equilibrium Drop Shapes on a Tilted Substrate with a Chemical Step.

We calculate the equilibrium shape of a droplet sitting on a tilted substrate with a "chemical step", that is, different lypophilicity at the two sides of the step. This problem can be generalized to that of a droplet experiencing a body force, pushing it from the lyophilic part to the lyophobic part of the substrate. We present phase diagrams, in which we show for which droplet sizes there are dynamically inaccessible equilibrium shapes. We also identify what determines the threshold volume. While this given system was studied previously in the literature using contact angle hysteresis laws, we present the full static thermodynamical solution of the interfacial energy including the contact energy, while omitting the hysteresis effects from the contact line.

Morphology of Evaporating Sessile Microdroplets on Lyophilic Elliptical Patches.

The evaporation of droplets occurs in a large variety of natural and technological processes such as medical diagnostics, agriculture, food industry, printing, and catalytic reactions. We study the different droplet morphologies adopted by an evaporating droplet on a surface with an elliptical patch with a different contact angle. We perform experiments to observe these morphologies and use numerical calculations to predict the effects of the patched surfaces. We observe that tuning the geometry of the patches offers control over the shape of the droplet. In the experiments, the drops of various volumes are placed on elliptical chemical patches of different aspect ratios and imaged in 3D using laser scanning confocal microscopy, extracting the droplet's shape. In the corresponding numerical simulations, we minimize the interfacial free energy of the droplet, by employing Surface Evolver. The numerical results are in good qualitative agreement with our experimental data and can be used for the design of micropatterned structures, potentially suggesting or excluding certain morphologies for particular applications. However, the experimental results show the effects of pinning and contact angle hysteresis, which are obviously absent in the numerical energy minimization. The work culminates with a morphology diagram in the aspect ratio vs relative volume parameter space, comparing the predictions with the measurements.

Actividad física y alimentación en estudiantes universitarios chilenos / Atividade física e alimentação em estudantes universitarios chilenos / Physical activity and eating behaviors among chilean university students

RESUMEN La sociedad occidental se caracteriza actualmente por comportamientos sedentarios en el trabajo, actividades domésticas, recreativas y de ocio, así también por la ingesta calórica desequilibrada y consumo indiscriminado de sal, azúcar y grasas saturadas. Chile no está ajeno a esta realidad: casi dos tercios de la población tiene sobrepeso, además de no practicar deportes ni actividad física. Objetivo: Describir los comportamientos alimentarios y la actividad física de estudiantes matriculados en programas de pregrado en ciencias de la salud y ciencias humanas en una universidad chilena, ubicada en la zona centro-sur del país. Material y método: Se realizó un estudio transversal, cuantitativo, con una muestra de 331 estudiantes, hombres y mujeres (20-24 años) que cursaban el tercer año de carreras de pregrado de una universidad del centro sur de Chile. Esta investigación utilizó la escala validada de origen colombiano "CEVJU-R2". Resultados: La mayoría de los y las estudiantes reconocieron tener comportamientos alimentarios poco saludables y más de la mitad desarrollan bajos niveles de actividad física, independiente de si cursaba una carrera de pregrado relacionada o no con la salud. Sin embargo, los y las estudiantes de profesiones de la salud obtienen levemente mejores puntajes en relación con sus pares de ciencias humanas. Conclusión: Los estudiantes universitarios, así como la población chilena, mantienen prácticas de actividad física y patrones de alimentación poco saludables.

ABSTRACT Western society is currently characterized by sedentary behavior at work, domestic, recreational and leisure activities, as well as unbalanced caloric intake and indiscriminate consumption of salt, sugar and saturated fats. Chile is no stranger to this reality: almost two thirds of the population is overweight, in addition to not practicing sports or any physical activity. Objective: To describe the eating behaviors and the physical activity of students enrolled in undergraduate programs in health sciences and human sciences at a Chilean university, located in the central-southern part of the country. Materials and methods: A cross-sectional, quantitative study was conducted with a sample of 331 students, men and women (20-24 years old), who were in the third year of undergraduate programs at a university in central-southern Chile. This research used the validated scale of Colombian origin "CEVJU-R2". Results: Most university students reported having unhealthy eating behaviors and more than half of them show low levels of physical activity, regardless of whether their undergraduate programs were related to health sciences or not. However, students of health-related professions scored slightly better in relation to their peers in the humanities. Conclusion: University students, as well as the Chilean population, show low levels of physical activity and unhealthy eating patterns.

RESUMO A sociedade ocidental é caracterizada atualmente por comportamentos sedentários no trabalho, atividades domésticas, recreativas e de lazer, assim como pela ingestão calórica desequilibrada e consumo indiscriminado de sal, açúcar e gorduras saturadas. Chile não é estranho a essa realidade: quase dois terços da população está com excesso de peso, além de não praticar esportes ou atividade física. Objetivo: Descrever os comportamentos alimentares e a atividade física de estudantes matriculados em programas de graduação em ciências da saúde e ciências humanas em uma universidade chilena, localizada na parte centro-sul do país. Material e método: Foi realizado um estudo transversal, quantitativo, com uma amostra de 331 estudantes, homens e mulheres (20 a 24 anos), que cursavam o terceiro ano de carreira em uma universidade do sul do Chile. Esta pesquisa utilizou a escala validada de origem colombiana "CEVJU-R2". Resultados: A maioria dos e das estudantes reconheceram ter comportamentos alimentares não saudáveis e mais da metade desenvolvem baixos níveis de atividade física, independentemente da área da carreira de graduação, relacionada ou não à saúde. Não obstante, os estudantes de profissões da saúde obtêm pontuações ligeiramente melhores em relação aos colegas de ciências humanas. Conclusão: Estudantes universitários, assim como a população chilena, mantêm práticas de atividade física e padrões alimentares pouco saudáveis.

Actividad física y alimentación en estudiantes universitarios chilenos / Physical activity and eating behaviors among chilean university students / Atividade física e alimentação em estudantes universitarios chilenos

RESUMEN La sociedad occidental se caracteriza actualmente por comportamientos sedentarios en el trabajo, actividades domésticas, recreativas y de ocio, así también por la ingesta calórica desequilibrada y consumo indiscriminado de sal, azúcar y grasas saturadas. Chile no está ajeno a esta realidad: casi dos tercios de la población tiene sobrepeso, además de no practicar deportes ni actividad física. Objetivo: Describir los comportamientos alimentarios y la actividad física de estudiantes matriculados en programas de pregrado en ciencias de la salud y ciencias humanas en una universidad chilena, ubicada en la zona centro-sur del país. Material y método: Se realizó un estudio transversal, cuantitativo, con una muestra de 331 estudiantes, hombres y mujeres (20-24 años) que cursaban el tercer año de carreras de pregrado de una universidad del centro sur de Chile. Esta investigación utilizó la escala validada de origen colombiano "CEVJU-R2". Resultados: La mayoría de los y las estudiantes reconocieron tener comportamientos alimentarios poco saludables y más de la mitad desarrollan bajos niveles de actividad física, independiente de si cursaba una carrera de pregrado relacionada o no con la salud. Sin embargo, los y las estudiantes de profesiones de la salud obtienen levemente mejores puntajes en relación con sus pares de ciencias humanas. Conclusión: Los estudiantes universitarios, así como la población chilena, mantienen prácticas de actividad física y patrones de alimentación poco saludables.

ABSTRACT Western society is currently characterized by sedentary behavior at work, domestic, recreational and leisure activities, as well as unbalanced caloric intake and indiscriminate consumption of salt, sugar and saturated fats. Chile is no stranger to this reality: almost two thirds of the population is overweight, in addition to not practicing sports or any physical activity. Objective: To describe the eating behaviors and the physical activity of students enrolled in undergraduate programs in health sciences and human sciences at a Chilean university, located in the central-southern part of the country. Materials and methods: A cross-sectional, quantitative study was conducted with a sample of 331 students, men and women (20-24 years old), who were in the third year of undergraduate programs at a university in central-southern Chile. This research used the validated scale of Colombian origin "CEVJU-R2". Results: Most university students reported having unhealthy eating behaviors and more than half of them show low levels of physical activity, regardless of whether their undergraduate programs were related to health sciences or not. However, students of health-related professions scored slightly better in relation to their peers in the humanities. Conclusion: University students, as well as the Chilean population, show low levels of physical activity and unhealthy eating patterns.

RESUMO A sociedade ocidental é caracterizada atualmente por comportamentos sedentários no trabalho, atividades domésticas, recreativas e de lazer, assim como pela ingestão calórica desequilibrada e consumo indiscriminado de sal, açúcar e gorduras saturadas. Chile não é estranho a essa realidade: quase dois terços da população está com excesso de peso, além de não praticar esportes ou atividade física. Objetivo: Descrever os comportamentos alimentares e a atividade física de estudantes matriculados em programas de graduação em ciências da saúde e ciências humanas em uma universidade chilena, localizada na parte centro-sul do país. Material e método: Foi realizado um estudo transversal, quantitativo, com uma amostra de 331 estudantes, homens e mulheres (20 a 24 anos), que cursavam o terceiro ano de carreira em uma universidade do sul do Chile. Esta pesquisa utilizou a escala validada de origem colombiana "CEVJU-R2". Resultados: A maioria dos e das estudantes reconheceram ter comportamentos alimentares não saudáveis e mais da metade desenvolvem baixos níveis de atividade física, independentemente da área da carreira de graduação, relacionada ou não à saúde. Não obstante, os estudantes de profissões da saúde obtêm pontuações ligeiramente melhores em relação aos colegas de ciências humanas. Conclusão: Estudantes universitários, assim como a população chilena, mantêm práticas de atividade física e padrões alimentares pouco saudáveis.

A multiobjective optimization procedure for the electrode design of cochlear implants.

This paper presents a new procedure to design optimal electrodes for cochlear implants. The main objective of this study is to find a set of electrode designs that maximize the focalization and minimize the power consumption simultaneously. To achieve that, a criterion to measure the ability of focalization of an electrode is proposed. It is presented a procedure to determine (1) the electrical potential induced by an electrode by solving the Laplace equation through the finite element method; (2) the response of a neuron to an applied field using NEURON, a compartmentalized cell model; (3) the optimization to find the best electrode designs according to power consumption and focalization by 2 evolutionary multiobjective methods based on the non-dominated sorting genetic algorithm II: a straight multiobjective approach and a seeded multiobjective approach. An electrode design formed by 2 conductive rings with a possible difference of potential between them is proposed. It is analyzed that the response of the neuron is determined by the shape and the difference of the potential between the electrode rings. Our procedure successfully achieves a nondominated set of optimum electrode designs improving a standard electrode in both objectives, as designs with better focalization allow to include extra electrodes in the cochlear implant, and designs with lower power consumption extend the length of the battery.

Zipping-Depinning: Dissolution of Droplets on Micropatterned Concentric Rings.

The control of the surface wettability is of great interest for technological applications as well as for the fundamental understanding of surface phenomena. In this article, we describe the dissolution behavior of droplets wetting a micropatterned surface consisting of smooth concentric circular grooves. In the experiments, a droplet of alcohol (1-pentanol) is placed onto water-immersed micropatterns. When the drops dissolve, the dynamics of the receding contact line occurs in two different modes. In addition to the stick-jump mode with jumps from one ring to the next inner one, our study reveals a second dissolution mode, which we refer to as zipping-depinning. The velocity of the zipping-depinning fronts is governed by the dissolution rate. At the early stage of the droplet dissolution, our experimental results are in good agreement with the theoretical predictions by Debuisson et al. [ Appl. Phys. Lett. 2011 , 99 , 184101 ]. With an extended model, we can accurately describe the dissolution dynamics in both stick-jump and zipping-depinning modes.

Calidad del servicio odontológico público basado en percepciones intangibles en paciente sin discapacidad y discapacitados. Talcahuano, Chile / Quality of public dental service based on intangibles perceptions in patients with and without disabilities. Talcahuano, Chile

La evaluación de los Servicios de salud para el mejoramiento de la calidad es una actividad que produce discusiones. El desarrollo de una metodología basada en la percepción de los usuarios sobre los intangibles del servicio es hoy más frecuente, cuidando la inclusión de todos los grupos como son familias con personas con discapacidad. Se estudió la población asignada a un Centro de Salud Familiar (CESFAM) mediante una encuesta validada en la metodología SERVPERF en los hogares a personas mayores de 14 años, con pacientes sin y con discapacidad atendidos bajo la modalidad pública. Se detectaron niveles de valoración con diferencias estadísticamente significativas, siendo más baja para los pacientes discapacitados. El mejoramiento pasa por un enriquecimiento del capital social, especialmente del personal de apoyo al profesional y de un fortalecimiento de elementos secundarios como son folleterías e instructivos. Hay que dar el sentido al servicio público: la satisfacción del usuario

The assessment of the health services for improvement of quality is an activity that produces discussions. The development of a new methodology based on the perception of users about intangibles of the service its today more frequent, taking care about the inclusion of all the groups like families with people with handicap members. It was studied the assigned population in a family health center through a survey validated with SERVPERF methodology in persons with more than 14 years old, with patients with disabilities and without them in the public system. It was detected levels of assessment with statistically significantly differences, the lowest rating was for patients with disabilities. The improvement involves enrichment of the social capital, especially of the back up personal to the professional and strengthening of secondary elements like educative printed material. We have to give a sense to the public service: the satisfaction of the users

Actitud del profesional de enfermería ante la muerte de pacientes / Professional nurse attitude towards the death of patients

Estudio descriptivo correlacionad cuyo propósito fue valorar la actitud de los profesionales de enfermería ante la muerte de pacientes, relacionándola con factores que la condicionan, como también identificar instancias de preparación en esta temática. La muestra estuvo constituida por 157 profesionales de enfermería de los hospitales Guillermo Grant Benavente de Concepción y Las Higueras de Talcahuano. Este estudio se sustentó en los conceptos actitud y muerte. Para recolectar la información se utilizó un instrumento con tres escalas: la primera, para Características Biosociodemográficas, tomado de Tejada, adaptado por los investigadores (1); la segunda, Escala de Medición de Actitud ante la Muerte, creado por Urrutia, citado en Tejada (1), y el tercero, el Cuestionario de Actitud hacia la Muerte (CAM), adaptación de Templer (2). Los resultados principales muestran que la edad, la preparación de pregrado acerca de la temática, la edad de su primer contacto con la muerte y los años de experiencia profesional influyen significativamente en la actitud del profesional de enfermería ante la muerte de pacientes. Esto permitió crear un modelo estadístico óptimo de factores predictores de la actitud del profesional de enfermería ante la muerte de pacientes. Se concluye que es muy importante que exista un espacio físico adecuado en los hospitales para la atención del paciente moribundo, así como también instancias de apoyo psicoemocional para los profesionales que enfrentan frecuentemente la muerte de pacientes. También es de relevancia, mejorar la preparación de pregrado y durante el desarrollo profesional, para reafirmar una actitud positiva que se refleje en una mejor atención y que disminuyan temores y ansiedad de las personas.

The purpose of this correlated descriptive study was to assess attitudes of nursing professionals towards the death of patients, related to conditional factors and preparation instances in this area. The sample was made up of 157 professional nurses from Guillermo Grant Benavente Hospital in Concepción, and Las Higueras Hospital in Talcahuano. This study was supported by attitude and death concepts. To collect information, an instrument with 3 scales of measure -ment was used. The first scale used to measure biosocial demographic points, was taken from Tejada, and adapted by the researchers (1). The second scale, used to measure attitude toward death, was created by Urrutia, mentioned in Tejada (1). The third scale, the Questionnaire of Attitude toward Death (CAM), was Templer's adaptation (2). Principal results show that age, undergraduate preparation in the subject, age at first contact with death and years of professional experience, have influence in nursing professionals' attitude toward the death of patients. This permits creating an optimal statistic model of predictable factors in the nursing professionals attitude toward the death of patients. It concludes that it is very important that there is an adequate physical space in hospitals for the attention of dying patients, as well as instances of psycho-emotional support for professionals that frequently face the death of patients. It is also very relevant to get better undergraduate preparation during professional development, to reaffirm a positive attitude, that will be demonstrated in better attention, and decrease of fears and anxiety.

Adherencia de las enfermeras/os a utilizar un modelo teórico como base de la valoración de enfermería / Adherence of nurses toward using a nursing model as a guideline for nursing assessment

Estudio cuasiexperimental que describe la adherencia de enfermeras hospitalarias a utilizar un modelo teórico como base de la valoración de enfermería, medida por la actitud y conducta hacia: valoración de enfermería, planificación del cuidado, conocimiento de modelos teóricos e importancia a realizar la valoración de enfermería en base aun modelo teórico. Una vez que el grupo experimental se capacitó en relación a modelos y teorías de enfemería y participó activamente en la elaboración de un instrumento de valoración, la adherencia se midió a través de las escalas de Actitud y de Conducta en Salud de Miller, adaptadas por los autores, y por la evidencia escrita en los registros. Para el análisis de los datos se usó la diferencia en diferencia mediante t de Student. Los resultados muestran que la adherencia medida por la actitud fue aceptada con una asociación estadística significativa; en cambio la adherencia medida por la conducta, no mostró diferencias significativas, resultados que fueron respaldados por la evidencia en los registros de enfermería de sólo un 11 por ciento de adherencia. Se concluye que los profesionales de enfermería, en términos de conductas adherentes, no evidenciaron cambios significativos antes y después del tratamiento experimental, pero se obtuvieron resultados positivos en términos cognitivos, ya que manifestó una actitud adherente a trabajar con un modelo teórico lo que es muy positivo para la profesión y es, por tanto, la motivación necesaria para lograr los cambios en el nuevo marco de la gestión del cuidado en enfermería.

Adulto mayores funcionales: un nuevo concepto en salud / Functionals elders: a new concept in health

Se revisa el concepto de funcionalidad en el adulto mayor, dentro de un contexto internacional y nacional, mencionando investigaciones realizadas en nuestro país y generalidades en relación a instrumentos de evaluación más utilizados, junto al papel del sector salud y en especial de enfermería. Finalmente se propone un programa de actividades destinadas a aumentar la funcionalidad del adulto mayor.

Calidad de Vida en pacientes renales hemodializados / Quality of life on patients hemodialysis

Estudio descriptivo de corte transversal, cuyo propósito fue conocer las características personales y calidad de vida de pacientes con insuficiencia renal crónica en tratamiento sustitutivo con hemodiálisis . El grupo de estudio estuvo constituido por 90 pacientes de dos centros de diálisis de la ciudad de Concepción, Chile. La calidad de vida se midió a través del cuestionario genérico de salud SF-36. Aproximadamente la mitad de los pacientes tenían entre 45 y 64 años, la distribución por sexo fue prácticamente similar, tres cuartas partes de los sujetos se declararon con pareja , más de la mitad poseía baja escolaridad y todos poseían algún sistema previsional. El valor más alto de calidad de vida fue 81,8 y el más bajo 3,25. Por lo que se pudo concluir que aproximadamente la mitad de las personas encuestadas tenía una calidad de vida por sobre el nivel promedio.