Utilidad de las redes neuronales artificiales en la asignación donante-receptor en trasplante hepático

El disbalance existente entre el número de donantes y receptores en trasplante hepático hizo que se comenzaran a utilizar donantes con criterios expandidos. Este tipo de donantes, por definición, tienen mayor riesgo de desarrollar una pobre función inicial (IPF), una no función primaria (PNF) del injerto e incluso pueden condicionar una pérdida tardía del mismo. Es sabido que tanto factores del donante como del receptor y factores propios histológicos, de la extracción, de la preservación e incluso del transporte y el implante están implicados en la probabilidad de disfunción orgánica. Así, establecer cuál es la probabilidad de disfunción del injerto mediante la creación de pares donante-receptor en función del riesgo de pérdida del mismo y de la evolución post-trasplante influenciada por multiples variables que acontecen durante todo el periodo de donación-implante-evolución es el objetivo del presente estudio. Para ello, se utilizarán redes neuronales artificiales, que no son otra cosa que algoritmos de cálculo que emulan la capacidad de aprendizaje del sistema nervioso, de tal manera, que la red neuronal identifica un patrón a seguir entre las variables de entrada y las de la salida, teniendo como variable final la supervivencia del injerto y del receptor. Existen actualmente algoritmos que establecen el riesgo de fallo del injerto después de un trasplante hepático, sin embargo, pocos estudios han intentado desarrollar modelos capaces de predecir la supervivencia post-trasplante (1). Estos estudios están basados en experiencias unicéntricas, que carecen de número suficientemente grande de casos para establecer modelos con variables pormenorizadas, y con resultados difíciles de validar fuera de los centros donde se llevaron a cabo. Además, algunos de ellos se han realizado sobre series relativamente antiguas y cuya extrapolación del modelo propuesto al momento actual del trasplante es difícil. Recientemente cuatro modelos de predicción de riesgo basados en variables del donante o del donante y receptor han permitido obtener modelos más realistas que no adolecen de estos inconvenientes (2,3,4,5). En cuanto a las redes neuronales, consisten, desde un punto de vista técnico, en un grupo de unidades de proceso (nodos) que se asemejan a las neuronas al estar interconectadas por medio de un entramado de relaciones (pesos) análogas al concepto de conexiones sinápticas en el sistema nervioso. A partir de los nodos de entrada, la señal progresa a través de la red hasta proporcionar una respuesta en forma de nivel de activación de los nodos de salida. En un contexto médico, el entrenamiento consistiría en presentar a la red, de forma iterativa, los valores de distintas variables clínicas (en forma de valores de la capa de entrada) de cada paciente y conseguir que la red sea capaz de predecir el estado final observado en cada paciente (indicados por el estado de las capas de salida de la red) de la manera más precisa posible (6,7). La posibilidad de resolver problemas difíciles es gracias a los principios de las redes neuronales. Los cinco más importantes son: aprendizaje adaptativo, autoorganización, tolerancia a fallos, operación en tiempo real y fácil inserción en la tecnología existente. Estas características las hacen perfectas para resolver problemas en campos tan variados como la agricultura, la bibliometria, economía y medicina (8,9,10)

A simulator to assess energy saving strategies and policies in HPC workloads

In recent years power consumption of high performance computing (HPC) clusters has become a growing problem due, e.g., to the economic cost of electricity, the emission of car- bon dioxide (with negative impact on the environment), and the generation of heat (which reduces hardware reliability). In past work, we developed EnergySaving cluster , a software package that regulates the number of active nodes in an HPC facility to match the users’ demands. In this paper, we extend this work by presenting a simulator for this tool that allows the evaluation and analysis of the benefits of applying different energy-saving strategies and policies, under realistic workloads, to different cluster configurations

Look-ahead in the two-sided reduction to compact band forms for symmetric eigenvalue problems and the SVD

We address the reduction to compact band forms, via unitary similarity transformations, for the solution of symmetric eigenvalue problems and the computation of the singular value decomposition (SVD). Concretely, in the first case, we revisit the reduction to symmetric band form, while, for the second case, we propose a similar alternative, which transforms the original matrix to (unsymmetric) band form, replacing the conventional reduction method that produces a triangular– band output. In both cases, we describe algorithmic variants of the standard Level 3 Basic Linear Algebra Subroutines (BLAS)-based procedures, enhanced with lookahead, to overcome the performance bottleneck imposed by the panel factorization. Furthermore, our solutions employ an algorithmic block size that differs from the target bandwidth, illustrating the important performance benefits of this decision. Finally, we show that our alternative compact band form for the SVD is key to introduce an effective look-ahead strategy into the corresponding reduction procedure

An Extension of the StarSs Programming Model for Platforms with Multiple GPUs

While general-purpose homogeneous multi-core architectures are becoming ubiquitous, there are clear indications that, for a number of important applications, a better performance/power ratio can be attained using specialized hardware accelerators. These accelerators require specific SDK or programming languages which are not always easy to program. Thus, the impact of the new programming paradigms on the programmer’s productivity will determine their success in the high-performance computing arena. In this paper we present GPU Superscalar (GPUSs), an extension of the Star Superscalar programming model that targets the parallelization of applications on platforms consisting of a general-purpose processor connected with multiple graphics processors. GPUSs deals with architecture heterogeneity and separate memory address spaces, while preserving simplicity and portability. Preliminary experimental results for a well-known operation in numerical linear algebra illustrate the correct adaptation of the runtime to a multi-GPU system, attaining notable performance results

Minimizing geminate recombination losses in small-molecule-based organic solar cells

Small-molecule-based organic solar cells (OSCs) are a recurrent alternative to polymer-based OSCs. Due to the higher purity and definition of small molecules compared to polymers, the morphological requirements can be more relaxed. Here, we present a series of novel rhodanine-based small-molecule electron donors and blend them with the standard acceptor PC70BM. By performing a target analysis on femtosecond spectroscopy data, we quantify the rates of geminate charge recombination. We are able to reproduce these rates by applying the Marcus–Levich–Jortner equation, using results from quantum chemical calculations. This shows that in a series of differently substituted compounds, one can correctly predict trends in geminate recombination rates by relying only on quantities that are easy to measure (cyclic voltammetry, optical spectra) or that can be calculated by relatively inexpensive methods such as (TD)DFT. Our method should thus accelerate the search for high-performance small-molecule photovoltaic blends

Virtual reality exercise intradialysis to improve physical function: A feasibility randomized trial

[EN] Objective The main objective of this investigation was to assess feasibility of conducting a future RCT with an intradialysis non-immersive virtual reality exercise intervention. The secondary aim was to explore the impact of either conventional or VR exercise on physical function. Design Feasibility randomized trial. Participants Eighteen subjects who participated in a 16-week intradialysis combined exercise program. Interventions The program lasted four additional weeks of either combined exercise or virtual reality exercise. Main outcome measures Physical function was measured through several reliable tests (sit-to-stand-to-sit tests 10 and 60, gait speed, one-leg heel-rise tests, and 6-minute walk test) at baseline, after 16 weeks of intradialysis combined exercise and by the end of four additional weeks of exercise. Adherence to the exercise programs was registered. Results There was a significant time effect, so that physical function improved in both groups. By the end of the 20 weeks, function improved as measured through the sit-to-stand-to-sit tests 10 and 60, gait speed, one-leg heel-rise left leg, and the 6-minute walk test. Changes that did not occur due to error in the test were seen after 20 weeks were achieved in the sit-to-stand-to-sit test 60, gait speed, one-leg heel-rise test for the left leg, and 6-minute walking test. Conclusion Virtual reality was a feasible intervention. Both interventions improved physical function. Adherence was not significantly different between groups.Universidad Cardenal Herrera-CEU, CEU Universities, Valencia, Spain, Grant/Award Number: Consolidacion de Indicadores CEU-UCH 2016-2017/ISegura-Orti, E.; Perez-Dominguez, B.; Ortega-Pérez De Villar, L.; Melendez-Oliva, E.; Martínez-Gramaje, J.; García-Maset, R.; Gil-Gómez, J. (2019). Virtual reality exercise intradialysis to improve physical function: A feasibility randomized trial. 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Exercise training in patients with end-stage renal disease on hemodialysis: Comparison of three rehabilitation programs. Journal of Rehabilitation Medicine, 34(1), 40-45. doi:10.1080/165019702317242695Corbetta, D., Imeri, F., & Gatti, R. (2015). Rehabilitation that incorporates virtual reality is more effective than standard rehabilitation for improving walking speed, balance and mobility after stroke: a systematic review. Journal of Physiotherapy, 61(3), 117-124. doi:10.1016/j.jphys.2015.05.017Peruzzi, A., Cereatti, A., Della Croce, U., & Mirelman, A. (2016). Effects of a virtual reality and treadmill training on gait of subjects with multiple sclerosis: a pilot study. Multiple Sclerosis and Related Disorders, 5, 91-96. doi:10.1016/j.msard.2015.11.002Brien, M., & Sveistrup, H. (2011). An Intensive Virtual Reality Program Improves Functional Balance and Mobility of Adolescents With Cerebral Palsy. Pediatric Physical Therapy, 23(3), 258-266. doi:10.1097/pep.0b013e318227ca0fOrtega‐Pérez de VillarL Pérez‐ DomínguezB Segura‐OrtíE et al.Use of virtual reality game as part of exercise program for chronic kidney disease patients undergoing haemodialysis.2015.Cho, H., & Sohng, K.-Y. (2014). The Effect of a Virtual Reality Exercise Program on Physical Fitness, Body Composition, and Fatigue in Hemodialysis Patients. Journal of Physical Therapy Science, 26(10), 1661-1665. doi:10.1589/jpts.26.1661OrtegaL.Comparison of two exercise programs for hemodialysis patients intradialysis vs home based program. absolute and relative reliability of physical performance[tesis doctoral]. Universidad CEU Cardenal Herrera. Facultad de Ciencias de la Salud;2017.Guralnik, J. M., Ferrucci, L., Simonsick, E. M., Salive, M. E., & Wallace, R. B. (1995). Lower-Extremity Function in Persons over the Age of 70 Years as a Predictor of Subsequent Disability. New England Journal of Medicine, 332(9), 556-562. doi:10.1056/nejm199503023320902Segura-Ortí, E., & Martínez-Olmos, F. J. (2011). Test-Retest Reliability and Minimal Detectable Change Scores for Sit-to-Stand-to-Sit Tests, the Six-Minute Walk Test, the One-Leg Heel-Rise Test, and Handgrip Strength in People Undergoing Hemodialysis. Physical Therapy, 91(8), 1244-1252. doi:10.2522/ptj.20100141Segura-Ortí, E. (2017). Fisioterapia sobre ejercicio en pacientes en hemodiálisis. Fisioterapia, 39(4), 137-139. doi:10.1016/j.ft.2017.05.003Bohm, C., Stewart, K., Onyskie-Marcus, J., Esliger, D., Kriellaars, D., & Rigatto, C. (2014). Effects of intradialytic cycling compared with pedometry on physical function in chronic outpatient hemodialysis: a prospective randomized trial. Nephrology Dialysis Transplantation, 29(10), 1947-1955. doi:10.1093/ndt/gfu248KOUFAKI, P., NASH, P. F., & MERCER, T. H. (2002). Assessing the efficacy of exercise training in patients with chronic disease. Medicine & Science in Sports & Exercise, 34(8), 1234-1241. doi:10.1097/00005768-200208000-00002Cappy, C. S., Jablonka, J., & Schroeder, E. T. (1999). The effects of exercise during hemodialysis on physical performance and nutrition assessment. Journal of Renal Nutrition, 9(2), 63-70. doi:10.1016/s1051-2276(99)90002-xHeadley, S., Germain, M., Mailloux, P., Mulhern, J., Ashworth, B., Burris, J., … Jones, M. (2002). Resistance training improves strength and functional measures in patients with end-stage renal disease. American Journal of Kidney Diseases, 40(2), 355-364. doi:10.1053/ajkd.2002.34520Painter, P., Carlson, L., Carey, S., Paul, S. M., & Myll, J. (2000). Low-functioning hemodialysis patients improve with exercise training. American Journal of Kidney Diseases, 36(3), 600-608. doi:10.1053/ajkd.2000.16200Segura-Ortí, E., Kouidi, E., & Lisón, J. F. (2009). Effect of resistance exercise during hemodialysis on physical function and quality of life: randomized controlled trial. 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Ruxolitinib in refractory acute and chronic graft-versus-host disease : a multicenter survey study

Graft-versus-host disease is the main cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation. First-line treatment is based on the use of high doses of corticosteroids. Unfortunately, second-line treatment for both acute and chronic graft-versus-host disease, remains a challenge. Ruxolitinib has been shown as an effective and safe treatment option for these patients. Seventy-nine patients received ruxolitinib and were evaluated in this retrospective and multicenter study. Twenty-three patients received ruxolitinib for refractory acute graft-versus-host disease after a median of 3 (range 1-5) previous lines of therapy. Overall response rate was 69.5% (16/23) which was obtained after a median of 2 weeks of treatment, and 21.7% (5/23) reached complete remission. Fifty-six patients were evaluated for refractory chronic graft-versus-host disease. The median number of previous lines of therapy was 3 (range 1-10). Overall response rate was 57.1% (32/56) with 3.5% (2/56) obtaining complete remission after a median of 4 weeks. Tapering of corticosteroids was possible in both acute (17/23, 73%) and chronic graft-versus-host disease (32/56, 57.1%) groups. Overall survival was 47% (CI: 23-67%) at 6 months for patients with aGVHD (62 vs 28% in responders vs non-responders) and 81% (CI: 63-89%) at 1 year for patients with cGVHD (83 vs 76% in responders vs non-responders). Ruxolitinib in the real life setting is an effective and safe treatment option for GVHD, with an ORR of 69.5% and 57.1% for refractory acute and chronic graft-versus-host disease, respectively, in heavily pretreated patients