Bankruptcy Prediction: A Comparison of Some Statistical and Machine Learning Techniques

We are interested in forecasting bankruptcies in a probabilistic way. Specifically, we compare the classification performance of several statistical and machine-learning techniques, namely discriminant analysis (Altman's Z-score), logistic regression, least-squares support vector machines and different instances of Gaussian processes (GP's) -that is GP's classifiers, Bayesian Fisher discriminant and Warped GP's. Our contribution to the field of computational finance is to introduce GP's as a potentially competitive probabilistic framework for bankruptcy prediction. Data from the repository of information of the US Federal Deposit Insurance Corporation is used to test the predictions.Bankruptcy prediction, Artificial intelligence, Supervised learning, Gaussian processes, Z-score.

A structural approach including the behavior of collagen cross-links to model patient-specific human carotid arteries

The final publication is available at Springer via http://dx.doi.org/10.1007/s10439-014-0995-7The objective of this work is to develop a remodeling model for biological matter coupling two different processes in a 3D framework: reorientation of the preferential direction of a given fibered structure and reorientation of the fibrils or filaments that make up such a structure. This work uses the microsphere-based approach to take into account the micro mechanics involved in biological fibered structures regarding both their passive behavior and the reorientation of their micro constituents. Moreover, the macro behavior of the material as a whole is obtained by means of homogenizing the underlying micro response. We associate the orientation space of the integration directions to the physical space of micro-fibrils. To approximate the directional distribution of the fibrils within each fiber bundle, a Bingham probability orientation density function is introduced into the Helmholtz energy function. With all these assumptions, the problem is studied from an energetic point of view, describing the dissipation inherent to remodeling processes, and the evolution equations for both reorientations (change in preferential direction of the network and change in shape of the fibril distribution) re obtained. The model is included in a finite element code which allows computing different geometries and boundary value problems. This results in a complete methodology for characterizing the reorientation evolution of different fibered biological structures, such as cells. Our results show remodeling of fibered structures in two different scales, presenting a qualitatively good agreement with experimental findings in cell mechanics. Hierarchical structures align in the direction of the maximum principal direction of the considered stimulus and narrow in the perpendicular direction. The dissipation rates follows predictable trends although there are no experimental findings to date for comparison. The incorporation of metabolic processes and an insight into cell-oriented mechano-sensing processes can help to overcome the limitations involved.Peer ReviewedPostprint (author's final draft

Covering functors without groups

Coverings in the representation theory of algebras were introduced for the Auslander-Reiten quiver of a representation finite algebra by Riedtmann and later for finite dimensional algebras by Bongartz and Gabriel, R. Martinez-Villa and de la Pe\~na. The best understood class covering functors is that of Galois covering functors F: A -> B determined by the action of a group of automorphisms of A. In this work we introduce the balanced covering functors which include the Galois class and for which classical Galois covering-type results still hold. For instance, if F:A -> B is a balanced covering functor, where A and B are linear categories over an algebraically closed field, and B is tame, then A is tame.Comment: Some improvements have been made; in particular, the proof of Theorem 2 has been restructured and clarifie

Refrigeration Capacity and Effect of Ageing on the Operation of Cellulose Evaporative Cooling Pads, by Wind Tunnel Analysis

This study investigates the temperature reduction capacity and water consumption of a fan-pad system installed in a greenhouse located in the coastal regions of Almería. The suitability of this system for coastal zones with high environmental humidity during the summer is analyzed. Historical temperature and relative humidity series are studied, obtaining the thermal difference and maximum, medium, and minimum monthly water consumption of the pads based on the operation data of the pads. Despite the high relative humidity of the air in the hottest hours of the day, a decrease of 5.92 ºC in the mean temperature and a water consumption of 13.55 l/h per square meter of an evaporative cooling pad are obtained in the month of August. Additionally, the operation of a cellulose evaporative cooling pad installed for 3 years in a greenhouse is analyzed in a wind tunnel and compared with that of a new pad of the same model. Over time and with low maintenance, the porosity of the pad decreases due to salt incrustation. The salt incrustation makes airflow more difficult in the pad, increasing the pressure drop by 170.04%; however, the air saturation efficiency of the pad increases by 6.6% due to the greater contact time between the air and the waterMinisterio de Economía y Competitividad de España AGL2015-68050-RUnión Europea (FEDER) AGL2015-68050-

Influencia del substrato en la estructura de la cobertera deslizada de las Sierras Marginales del Prepirineo de Huesca

El presente trabajo es un estudio estructural de un sector de Prepirineo de la provincia de Huesca ubicado en la zona de transición entre las Sierras Marginales Aragonesas y las Catalanas. Se argumenta la existencia de un accidente del substrato, activo si multáneamente al desplazamiento hacia el S de la cobertera despegad

Computational modeling of hypertensive growth in the human carotid artery

The final publication is available at Springer via http://dx.doi.org/10.1007/s00466-013-0959-zArterial hypertension is a chronic medical condition associated with an elevated blood pressure. Chronic arterial hypertension initiates a series of events, which are known to collectively initiate arterial wall thickening. However, the correlation between macrostructural mechanical loading, microstructural cellular changes, and macrostructural adaptation remains unclear. Here, we present a microstructurally motivated computational model for chronic arterial hypertension through smooth muscle cell growth. To model growth, we adopt a classical concept based on the multiplicative decomposition of the deformation gradient into an elastic part and a growth part. Motivated by clinical observations, we assume that the driving force for growth is the stretch sensed by the smooth muscle cells. We embed our model into a finite element framework, where growth is stored locally as an internal variable. First, to demonstrate the features of our model, we investigate the effects of hypertensive growth in a real human carotid artery. Our results agree nicely with experimental data reported in the literature both qualitatively and quantitatively.Peer ReviewedPostprint (author's final draft

Mathematical modeling of collagen turnover in biological tissue

The final publication is available at Springer via http://dx.doi.org/10.1007/s00285-012-0613-yWe present a theoretical and computational model for collagen turnover in soft biological tissues. Driven by alterations in the mechanical environment, collagen fiber bundles may undergo important chronic changes, characterized primarily by alterations in collagen synthesis and degradation rates. In particular, hypertension triggers an increase in tropocollagen synthesis and a decrease in collagen degradation, which lead to the well-documented overall increase in collagen content. These changes are the result of a cascade of events, initiated mainly by the endothelial and smooth muscle cells. Here, we represent these events collectively in terms of two internal variables, the concentration of growth factor TGF-$\beta$ and tissue inhibitors of metalloproteinases TIMP. The upregulation of TGF-$\beta$ increases the collagen density. The upregulation of TIMP also increases the collagen density through decreasing matrix metalloproteinase MMP. We establish a mathematical theory for mechanically-induced collagen turnover and introduce a computational algorithm for its robust and efficient solution. We demonstrate that our model can accurately predict the experimentally observed collagen increase in response to hypertension reported in literature. Ultimately, the model can serve as a valuable tool to predict the chronic adaptation of collagen content to restore the homeostatic equilibrium state in vessels with arbitrary micro-structure and geometry.Peer ReviewedPostprint (author's final draft

Thermography and Sonic Anemometry to Analyze Air Heaters in Mediterranean Greenhouses

The present work has developed a methodology based on thermography and sonic anemometry for studying the microclimate in Mediterranean greenhouses equipped with air heaters and polyethylene distribution ducts to distribute the warm air. Sonic anemometry allows us to identify the airflow pattern generated by the heaters and to analyze the temperature distribution inside the greenhouse, while thermography provides accurate crop temperature data. Air distribution by means of perforated polyethylene ducts at ground level, widely used in Mediterranean-type greenhouses, can generate heterogeneous temperature distributions inside the greenhouse when the system is not correctly designed. The system analyzed in this work used a polyethylene duct with a row of hot air outlet holes (all of equal diameter) that expel warm air toward the ground to avoid plant damage. We have observed that this design (the most widely used in Almería’s greenhouses) produces stagnation of hot air in the highest part of the structure, reducing the heating of the crop zone. Using 88 kW heating power (146.7 W∙m−2) the temperature inside the greenhouse is maintained 7.2 to 11.2 °C above the outside temperature. The crop temperature (17.6 to 19.9 °C) was maintained above the minimum recommended value of 10 °C

Integration of alternative and complementary therapies in the national health system

Trabajo fin de grado en EnfermeríaObjetivo: explorar la situación actual respecto al empleo e integración de las terapias alternativas y complementarias (TAC) en el Sistema Nacional de Salud (SNS) y otros sistemas sanitarios convencionales, así como reconocer el papel de la disciplina enfermera en este contexto. Metodología: se realizó una revisión narrativa mediante la consulta en las bases de datos: PubMed, Cochrane Library, Scielo, CINALH y CUIDEN. Para ello, se utilizó vocabulario controlado y libre, y los operadores booleanos “AND” y “OR”. La búsqueda bibliográfica se limitó a los documentos publicados entre 2012 y 2018, escritos en castellano, inglés, francés y portugués, y con acceso al resumen. Los artículos se seleccionaron en base a unos criterios de inclusión y exclusión fijados. Resultados: Se seleccionaron un total de 28 artículos que se revisaron según las siguientes unidades de análisis: uso y prevalencia de las TAC; inclusión de la MTC en los sistemas sanitarios convencionales y el SNS; regulación relacionada con la situación actual de las TAC; opinión de la población, estudiantes y profesionales respecto a la MTC; formación e investigación en TAC y sus consideraciones de seguridad e implicaciones para la disciplina enfermera. Conclusión: La integración de la MTC en los sistemas de salud basados en el método convencional de atención sería muy enriquecedor y beneficioso para la población en general, el usuario y el profesional sanitario, y muy especialmente para la enfermería que, como disciplina, debe adquirir un papel protagonista en este cambio. Para ello, es indispensable desarrollar investigaciones de calidad que utilicen diseños metodológicos adecuados y permitan garantizar la efectividad y seguridad de las TAC.Objective: To explore the current situation about the employment and integration of complementary alternative and therapies (CAT) in the National Health System (NHS) and other conventional health systems, as well as to recognize the role of the nurse discipline in this context. Methodology: A narrative review made by consulting the databases: PubMed, Cochrane Library, Scielo, CINALH and CUIDEN. For this, we use controlled and free vocabulary, as well as the boolean operators "AND" and "OR". The bibliographic search was limited to the documents published between 2012 and 2018, written in Spanish, English, French and Portuguese, and with access to the abstract. The articles were selected based on the inclusion and exclusion criteria set. Results: A total of 28 articles were selected, which were reviewed according to the following units of analysis: use and prevalence of the TAC; inclusion of the traditional and complementary medicine (TCM) in modern healthcare systems and; regulation related to the current situation of CAT; opinion of the population, students and professionals regarding the TCM; training and research in CAT and its security considerations and implications for the nurse discipline. Conclusion: The integration of TCM in health systems based on the conventional method of care would be very enriching and beneficial for the general population, the user and 3 the healthcare professional, and especially for nursing which, as a discipline, should acquire a leading role in this change. To do this, it is essential to develop quality research that uses appropriate methodological designs and ensures the effectiveness and safety of CAT