Energy conversion theorems for some linear steady-states

One of the main issues that real energy converters present, when they produce effective work, is the inevitable entropy production. Within the context of Non-equilibrium Thermodynamics, entropy production tends to energetically degrade man-made or living systems. On the other hand, it is also not useful to think about designing an energy converter that works in the so-called minimum entropy production regime since the effective power output and efficiency are zero. In this manuscript, we establish some \textit{Energy Conversion Theorems} similar to Prigogine's one with constrained forces, their purpose is to reveal trade-offs between design and the so-called operation modes for $\left(2\times2\right)$--linear isothermal energy converters. The objective functions that give rise to those thermodynamic constraints show stability. A two--meshes electric circuit was built as an example to demonstrate the Theorems' validity. Likewise, we reveal a type of energetic hierarchy for power output, efficiency and dissipation function when the circuit is tuned to any of the operating regimes studied here: maximum power output ($MPO$), maximum efficient power ($MP\eta$), maximum omega function ($M\Omega$), maximum ecological function ($MEF$), maximum efficiency ($M\eta$) and minimum dissipation function ($mdf$).Comment: 33 pages, 15 figures, 2 table

Generation of synthetic abdominal ecg signals from an abdominal 3D model

El electrocardiograma abdominal es una técnica de monitoreo promisoria para la vigilancia en el periodo prenatal, ya que presenta facilidad de adquisición y permite la supervisión materna y fetal simultáneamente. La separación de estas señales es complicada y no existe una forma estandarizada de evaluar la efectividad de algoritmos reportados en la literatura. Basados en un modelo de dipolo propagado en el abdomen materno tridimensional, el presente trabajo propone la implementación de un sistema de generación de señales de ECG abdominal, con características controlables de simulación de condiciones reales: interferencias, variabilidad de periodos cardiacos, número de canales, ubicación de electrodos y posición fetal. Con el sistema desarrollado se generaron 50 señales sintéticas de prueba que mostraron una correlación de 0,99 con respecto a valores esperados en la relación señal-interferencia, sin diferencias significativas en la regresión (p>0.05); mientras que el coeficiente de correlación para la relación señal a ruido fue de 0.87 con diferencias significativas en la regresión por debajo de los -20 dB (p<0.05). En conclusión, el sistema propuesto proporciona señales de ECG abdominal con condiciones similares a las de señales reales, lo cual facilita la adecuada evaluación de algoritmos de separación de ECG materno y fetal a partir del ECG abdominal.Abdominal ECG is one of the most promising monitoring techniques for fetal surveillance in the antenatal period, as it presents easy availability and allows the maternal and fetal monitoring simultaneously. However, separation of these signals is complicated and there is no standardized way to evaluate the effectiveness of separation algorithms reported in the literature. Based on the dipole model spread through the three-dimensional maternal abdomen, this paper proposes the implementation of a system for the generation of abdominal ECG signals with controllable characteristics simulating real conditions by interference, heart period variability, number of channels , electrodes location and fetal position. Using the developed system, 50 synthetic test signals were generated and compared with desired values. Results showed a correlation of 0.99 with respect to expected values in the signal interference ratio, with no significant differences in the regression (p>0.05); while the correlation coefficient was 0.87 for the signal to noise ratio, with significant differences below -20 dB (p<0.05) in the regression. In conclusion, the proposed system provides abdominal ECG signals showing similar conditions to those of real signals, and comprises a tool that ensures proper evaluation of separation algorithms of maternal and fetal ECG from abdominal ECG

Evaluation of Functional Capacity by Six- Minute Walk Test in Pediatric Asthma Patients

Los pacientes con asma muestran menor tolerancia al ejercicio. La prueba de caminata de 6 minutos (6MWD) evalúa la capacidad funcional (CF). La actividad física eleva los puntajes en el Cuestionario de autopercepción física (PSPQ)

Applications of Hilbert Module Approach to Multivariable Operator Theory

A commuting $n$-tuple $(T_1, \ldots, T_n)$ of bounded linear operators on a Hilbert space \clh associate a Hilbert module $\mathcal{H}$ over $\mathbb{C}[z_1, \ldots, z_n]$ in the following sense: $$\mathbb{C}[z_1, \ldots, z_n] \times \mathcal{H} \rightarrow \mathcal{H}, \quad \quad (p, h) \mapsto p(T_1, \ldots, T_n)h,$$where $p \in \mathbb{C}[z_1, \ldots, z_n]$ and $h \in \mathcal{H}$. A companion survey provides an introduction to the theory of Hilbert modules and some (Hilbert) module point of view to multivariable operator theory. The purpose of this survey is to emphasize algebraic and geometric aspects of Hilbert module approach to operator theory and to survey several applications of the theory of Hilbert modules in multivariable operator theory. The topics which are studied include: generalized canonical models and Cowen-Douglas class, dilations and factorization of reproducing kernel Hilbert spaces, a class of simple submodules and quotient modules of the Hardy modules over polydisc, commutant lifting theorem, similarity and free Hilbert modules, left invertible multipliers, inner resolutions, essentially normal Hilbert modules, localizations of free resolutions and rigidity phenomenon. This article is a companion paper to "An Introduction to Hilbert Module Approach to Multivariable Operator Theory".Comment: 46 pages. This is a companion paper to arXiv:1308.6103. To appear in Handbook of Operator Theory, Springe

Detection of latent tuberculosis infection in peritoneal dialysis patients: new methods

Introducción: El riesgo de tuberculosis (TB) está aumentadoen pacientes con insuficiencia renal crónica y en diálisis. Laprueba de la tuberculina (PT) es el test de cribado clásico enestos pacientes, a pesar de su baja sensibilidad. En los últi-mos años se han desarrollado nuevos métodos diagnósticosque se basan en la producción de interferón gamma tras laestimulación con antígenos de M. tuberculosis. El objetivo deeste estudio fue evaluar si el Quantiferon®TB-gold In Tube(QFT-GIT) puede contribuir en el diagnóstico de la infeccióntuberculosa en pacientes en diálisis peritoneal (DP). Pacien-tes y métodos:Se incluyeron 54 pacientes en DP. Se valoróla posibilidad de infección tuberculosa latente mediante elQFT-GIT, la PT y la valoración clinicorradiológica por parte deun neumólogo experto. Se estudiaron las concordancias en-tre los tests. Resultados: La prevalencia de un resultado posi-tivo para el test de la tuberculina fue del 29,6% para el pri-mer test y del 31,5% para el segundo (valorando el efectobooster). Una radiografía de tórax positiva aumentaba la de-tección de infección tuberculosa latente hasta un 42,6% y ladel neumólogo hasta un 44,4%. El nivel de correlación entreel QFT-GIT y la PT fue moderado (kappa = 0,36; p = 0,006), aligual que entre la PT y la valoración del neumólogo (kappa= 0,257, p = 0,06). Conclusiones: El QFT-GIT aporta algunasventajas en el diagnóstico de la infección tuberculosa en pa-cientes con insuficiencia renal crónica en DP, y puede com-plementar a la prueba de la tuberculina.Objective: The risk for tuberculosis (TB) is increased in patients with chronic renal failure and dialysis. Tuberculin skin test (TST) is the classical diagnostic method for screening despite its low sensitivity. New methods based on interferon-gamma have been developed. The aim of this study was to evaluate if Quantiferon® TB-gold In Tube (QFTGIT) could be useful in the diagnosis of TB infection in patients on peritoneal dialysis (PD). Patients and methods: Fifty-four patients on PD were included in the study. They were evaluated for latent tuberculosis with QFT-GIT, TST and an assessment by an expert pulmonologist using patients medical history and x-rays. Agreement between test results was determined. Results:The prevalence of a positive TST was 29.6% for the first test and 31.5% for the second (booster effect). A positive chest x-ray increased the rate of detection of patients with latent TB infection up to 42.6% and the expert physician?s evaluation to 44.4%. The correlation between QFT-GIT and TST was fair ( =0.36; P=.006), as it was between TST and expert physician?s evaluation ( =0.257; P=.06). Conclusions: According to our experience QFT-GIT represents an important advantage in the diagnosis of latent TB infection in chronic renal failure patients on PD. It may complement but not replace TST

Asymptotically Lifshitz wormholes and black holes for Lovelock gravity in vacuum

Static asymptotically Lifshitz wormholes and black holes in vacuum are shown to exist for a class of Lovelock theories in d=2n+1>7 dimensions, selected by requiring that all but one of their n maximally symmetric vacua are AdS of radius l and degenerate. The wormhole geometry is regular everywhere and connects two Lifshitz spacetimes with a nontrivial geometry at the boundary. The dynamical exponent z is determined by the quotient of the curvature radii of the maximally symmetric vacua according to n(z^2-1)+1=(l/L)^2, where L corresponds to the curvature radius of the nondegenerate vacuum. Light signals are able to connect both asymptotic regions in finite time, and the gravitational field pulls towards a fixed surface located at some arbitrary proper distance to the neck. The asymptotically Lifshitz black hole possesses the same dynamical exponent and a fixed Hawking temperature given by T=z/(2^z pi l). Further analytic solutions, including pure Lifshitz spacetimes with a nontrivial geometry at the spacelike boundary, and wormholes that interpolate between asymptotically Lifshitz spacetimes with different dynamical exponents are also found.Comment: 19 pages, 1 figur

History of fires and vegetation since the Neolithic in the Cantabrian Mountains (Spain)

Fire has been one of the main causes of disturbance of vegetation over time, and since the Neolithic has become an irreplaceable tool for the opening of forest spaces and maintenance of pastures. Previous studies showed that the intensity and effects of wildfires are related to the biomass and controlled by climate factors. However, in regions such as Cantabria, where agriculture and livestock have spread throughout the territory since prehistory, fires should also be closely related to human land uses. The aim of this paper was to investigate the history of fires and vegetation since the Neolithic in the Cantabrian Mountains, using sedimentary charcoal and pollen data to study the role of human activities in the processes that have shaped ecosystems throughout the Holocene. The asynchrony and quantitative differences in the results obtained at different sites indicate significant variations in fire patterns at regional scale since the Neolithic, although the type and size of each basin also had a strong influence on charcoal accumulation. Maximum values for charcoal accumulation rate at La Molina were observed between the Neolithic and the Bronze Age but occurred after about 3500 cal years BP at El Cueto de la Avellanosa. At El Sertal, low charcoal accumulation rate values were observed, probably because the sequence begins in a space that already had been cleared; the maximum values occurred during the most recent millennium. These data provide evidence that fire has been a key factor in forest retreat and in maintaining open landscapes since the Neolithic.This article was made possible by two Coordinated Project grants from Spain's Ministry of Economics and Competitiveness (MEC), “El uso del fuego y la conformación de los paisajes en la Montaña cantábrica y el Pirineo oriental: estudio comparado de su evolución histórica y tendencias actuales” (CSO2012-39680-C02-01) awarded to the Department of Geography, Urban studies and Land Planning, Universidad de Cantabria and “Geohistoria ambiental del fuego en el Holoceno. Patrones culturales y gestión territorial desde el inicio de la ganadería y la agricultura en la montaña Cantábrica y Pirineo “awarded to the Department of Geography, Universitat Autónoma de Barcelona (CSO2012-39680-C02-02). In addition, the project was funded by the Catalan government's Applied Geography program, “Grup de Geografia Aplicada” (AGAUR, Generalitat de Catalunya, 2014 SGR 1090)

La formación de educadores ambientales en México: avances y perspectivas

RESUMEN La formación de educadores ambientales fue planteada como un imperativo del campo desde los primeros años de su implantación en México. Si bien el desarrollo de programas de profesionalización en la forma de diplomados, especializaciones y maestrías ha sido continuo, también ha sido vulnerable a los cambios en las propias universidades de adscripción, así como a los de las políticas ambientales gubernamentales. El presente artículo da cuenta de esta historia. Se conceptualiza el problema, se resume el perfil actual que se observa y se apuntan algunas salidas que se han ido construyendo para fortalecer este campo. En este sentido, destaca especialmente el hecho de que diversas maestrías y doctorados en ciencias o en educación aceptan propuestas de investigación en educación ambiental. Con ello, la esfera de profesionalización se ha expandido más allá del circuito de los educadores ambientales, lo que ha favorecido el diálogo y los intercambios creativos y productivos con otras áreas de conocimiento y alrededor de diversas temáticas, entre ellas lo intercultural, la conservación, las ciencias, el cambio climático, la literatura y la poesía, entre otras, que en su conjunto ofrecen una perspectiva sobre los procesos de profesionalización de los educadores ambientales en México