30 research outputs found
Chemical physics insight of PPy-based modified ion exchange membranes: a fundamental approach
Four commercially available, cost-effective ion exchange membranes (two cationic and two anionic exchange membranes, CEMs and AEMs, respectively) were modified to mitigate crossover phenomena of the redox active species typically observed in Aqueous Organic Redox Flow Batteries (AORFB) systems. The modification strategy was carried out using a pyrrole(Py)-based polymer which successfully reduced the permeation of two redox active organic molecules, a viologen derivative (named BP7 throughout this study) and TEMPOL, by an order of magnitude. Additionally, modified membranes showed not significant changes in ion conductivity, with negligible effect on the electrical conductivity of the membranes at a given conditions. The morphology, physicochemical, mechanical, and electrochemical properties of the membranes were determined to evaluate the impact of these modifications. AEMs modified in this manner were found to have optimal properties, showing an increase in ion exchange capacity while maintaining excellent mechanical stability and unaltered permselectivity. Additionally, the diffusion boundary layer of these AEMs was slightly extended, which suggests a greater double layer stability for ion exchange processes than in the case of CEMs. Our work shows that these modified membranes could be an appealing approach for AORFB applicationsThis work has been funded by the European Union under the HIGREEW project, Affordable High-performance Green Redox Flow batteries (Grant agreement no. 875613). H2020: LC-BAT-4-2019875613
A general piecewise multi-state survival model: Application to breast cancer
Multi-state models are considered in the field of survival analysis for modelling
illnesses that evolve through several stages over time. Multi-state models can be
developed by applying several techniques, such as non-parametric, semi-parametric
and stochastic processes, particularly Markov processes. When the development of
an illness is being analysed, its progression is tracked periodically. Medical reviews
take place at discrete times, and a panel data analysis can be formed. In this paper, a
discrete-time piecewise non-homogeneous Markov process is constructed for
modelling and analysing a multi-state illness with a general number of states. The
model is built, and relevant measures, such as survival function, transition probabilities, mean total times spent in a group of states and the conditional probability of
state change, are determined. A likelihood function is built to estimate the parameters and the general number of cut-points included in the model. Time-dependent
covariates are introduced, the results are obtained in a matrix algebraic form and the
algorithms are shown. The model is applied to analyse the behaviour of breast
cancer. A study of the relapse and survival times of 300 breast cancer patients who
have undergone mastectomy is developed. The results of this paper are implemented
computationally with MATLAB and R.Ministerio de Economía y Competitividad FQM-307European Regional Development Fund (ERDF) MTM2017-88708-PUniversity of Milano-Bicocca 2014-ATE-022
Regular insulin added to total parenteral nutrition vs subcutaneous glargine in non-critically ill diabetic inpatients, a multicenter randomized clinical trial: INSUPAR trial
Background: There is no established insulin regimen in T2DM patients receiving parenteral nutrition. Aims: To compare the effectiveness (metabolic control) and safety of two insulin regimens in patients with diabetes receiving TPN. Design: Prospective, open-label, multicenter, clinical trial on adult inpatients with type 2 diabetes on a non-critical setting with indication for TPN. Patients were randomized on one of these two regimens: 100% of RI on TPN or 50% of Regular insulin added to TPN bag and 50% subcutaneous Gl. Data were analyzed according to intention-to-treat principle. Results: 81 patients were on RI and 80 on GI. No differences were observed in neither average total daily dose of insulin, programmed or correction, nor in capillary mean blood glucose during TPN infusion (165.3 +/- 35.4 in RI vs 172.5 +/- 43.6 mg/dL in GI; p = 0.25). Mean capillary glucose was significantly lower in the GI group within two days after TPN interruption (160.3 +/- 45.1 in RI vs 141.7 +/- 43.8 mg/dL in GI; p = 0.024). The percentage of capillary glucose above 180 mg/dL was similar in both groups. The rate of capillary glucose <= 70 mg/dL, the number of hypoglycemic episodes per 100 days of TPN, and the percentage of patients with non-severe hypoglycemia were significantly higher on GI group. No severe hypoglycemia was detected. No differences were observed in length of stay, infectious complications, or hospital mortality. Conclusion: Effectiveness of both regimens was similar. GI group achieved better metabolic control after TPN interruption but non-severe hypoglycemia rate was higher in the GI group. (C) 2019 The Author(s). Published by Elsevier Ltd
A flowgraph model for bladder carcinoma
Background: Superficial bladder cancer has been the subject of numerous studies for many years, but the evolution of the disease still remains not well understood. After the tumor has been surgically removed, it may reappear at a similar level of malignancy or progress to a higher level. The process may be reasonably modeled by means of a Markov process. However, in order to more completely model the evolution of the disease, this approach is insufficient. The semi-Markov framework allows a more realistic approach, but calculations become frequently intractable. In this context, flowgraph models provide an efficient approach to successfully manage the evolution of superficial bladder carcinoma. Our aim is to test this methodology in this particular case.
Results: We have built a successful model for a simple but representative case. Conclusion: The flowgraph approach is suitable for modeling of superficial bladder
cancer.Rubio Navarro, G.; García Mora, MB.; Santamaria Navarro, C.; Pontones Moreno, JL. (2014). A flowgraph model for bladder carcinoma. Theoretical Biology and Medical Modelling. 11(1):1-11. doi:10.1186/1742-4682-11-S1-S3S111111van Rhijn BW, Burger M, Lotan Y, Solsona E, Stief CG, Sylvester RJ, Witjes JA, Zlotta AR: Recurrence and progression of disease in non-muscle-invasive bladder cancer: from epidemiology to treatment strategy. Eur Urol. 2009, 56: 430-42. 10.1016/j.eururo.2009.06.028.Sylvester RJ, van der Meijden AP, Oosterlinck W, Witjes JA, Bouffioux C, Denis L, Newling DW, Kurth K: Predicting recurrence and progression in individual patients with stage Ta T1 bladder cancer using EORTC risk tables: a combined analysis of 2596 patients from seven EORTC trials. Eur Urol. 2006, 49: 475-7.Fernández-Gómez J, Madero R, Solsona E, Unda M, neiro LMP, González M, Portillo J, Ojea A, Pertusa C, Rodríguez-Molina J, Camacho J, Rabadan M, Astobieta A, Montesinos M, Isorna S, nola PM, Gimeno A, Blas M, neiro JAMP: The EORTC Tables Overestimate the Risk of Recurrence and Progression in Patients with Non-Muscle-Invasive Bladder Cancer Treated with Bacillus Calmette-Guerin: External Validation of the EORTC Risk Tables. Eur Urol. 2011, 60: 423-30. 10.1016/j.eururo.2011.05.033.Butler RW, Huzurbazar AV: Stochastic network models for survival analysis. J Am Statist Assoc. 1997, 92: 246-57. 10.1080/01621459.1997.10473622.Klein JP, Moeschberger ML: Suvival Analysis Techniques for Censored and Truncated Data. 2003, Springer, segundaNeuts MF: Matrix Geometric Solutions in Stocastic Models An Algoritmic Approach. 1981, Baltimore: The Johns Hopkins University PressLatouche G, Ramaswami V: Introduction to Matrix Analytic Methods in Stochastic Modeling. 1999, Philadelphia: SIAMPérez-Ocón R, Segovia MC: Modeling lifetimes using phase-type distributions. Risk, Reliability and Societal Safety, Proceedings of the European Safety and Reliability Conference 2007 (ESREL 2007). Edited by: Taylor & Francis re. 2007Huzurbazar A, Williams B: Incorporating Covariates in Flowgraph Models: Applications to Recurrent Event Data. Thecnometrics. 2010, 52: 198-208. 10.1198/TECH.2010.08044.Collins DH, Huzurbazar AV: System reliability and safety assessment using non-parametric flowgraph models. Proceedings of the Institution of Mechanical Engineers, Part O: Journal of Risk and Reliability December 1, 2008 vol 222 no 4. 2008, 667-664.Huzurbazar A: Multistate Models, Flowgraph Models, and Semi-Markov Processes. Communications in Statistics - Theory and Methods. 2004, 33: 457-474. 10.1081/STA-120028678.Huzurbazar A: Flowgraph Models for Multistate Time-To-Event Data. 2005, New York: WileyMullen KM, van Stokkum IHM: nnls: The Lawson-Hanson algorithm for non-negative least squares (NNLS). 2012, [R package version 1.4], http://CRAN.R-project.org/package=nnlsAbate J, Whitt W: The Fourier-Series Method For Inverting Transforms Of Probability Distributions. Queueing Syst. 1992, 5-88.Collins DH, Huzurbazar AV: Prognostic models based on statistical flowgraphs. Appl Stochastic Models Bus Ind. 2012, 28: 141-51. 10.1002/asmb.884.OMS: International Classification of Tumours. 1999, 2™, World Health Organization, Histological typing of urinary bladder tumours, Volumen 10, GenevaLujan S: Modelización matemática de la multirrecidiva y heterogeneidad individual para el cálculo del riesgo biológico de recidiva y progresión del tumor vesical no músculo invasivo. PhD thesis. 2012, Universitat de ValènciaTeam RDC: R: A Language and Environment for Statistical Computing. 2010, R Foundation for Statistical Computing, Vienna, Austria,Goulet V, Dutang C, Maechler M, Firth D, Shapira M, Stadelmann M, expm-developers@listsR-forgeR-projectorg: expm: Matrix exponential. 2011, [R package version 0.98-5], http://CRAN.R-project.org/package=expmBates D, Maechler M: Matrix: Sparse and Dense Matrix Classes and Methods. 2011, R package version 1.0-1.Therneau T: survival: Survival analysis, including penalised likelihood. 2011, original Splus: R port by Thomas Lumley, [R package version 2.36-10], http://CRAN.R-project.org/package=survivalJackson CH: Multi-State Models for Panel Data: The msm Package for R. Journal of Statistical Software. 2011, 38 (8): 1-29. http://www.jstatsoft.org/v38/i08
Pacientes españoles con síndrome de hipoventilación central incluidos en el Registro europeo. Datos del 2015
Introducción
El síndrome de hipoventilación central congénita (SHCC) es una enfermedad genética muy rara causada por mutaciones en PHOX2B; en 2010 se creó el Consorcio Europeo del Síndrome de Hipoventilación Central, que en 2012 implantó un Registro online de pacientes para optimizar su cuidado. Objetivo Conocer las características y la evolución de los pacientes españoles con SHCC y detectar áreas de mejora.
Materiales y método
Se analizaron los datos actualizados en diciembre del 2015 de los pacientes españoles del Registro europeo. Resultados Se registró a 38 pacientes, nacidos entre 1987 y 2013, procedentes de 18 hospitales. El 34, 2% eran mayores de 18 años. Han fallecido 3 pacientes. Aportaban estudio del gen PHOX2B 37 (97, 3%), 32 (86, 5%) con mutación. Los genotipos 20/25, 20/26 y 20/27 representaron el 84, 3% de las mutaciones. Las disautonomías fueron más frecuentes y graves en portadores de genotipos con mayores expansiones de polialaninas. El 47% de pacientes asociaba alteraciones oculares, el 16% Hirschsprung, el 13% hipoglucemias y el 5% tumores. Treinta pacientes (79%) debutaron en el periodo neonatal y 8 (21%) posteriormente (inicio/diagnóstico tardío). Ocho niños (21%) recibieron inicialmente ventilación domiciliaria con mascarilla; 5 eran lactantes con comienzo neonatal, 2 de ellos precisaron cambio a traqueostomía tras presentar parada cardiorrespiratoria; ambos tenían mutaciones graves. Han sido decanulados y transferidos a mascarilla el 34, 3% de los pacientes (edad media: 13, 7 años). El 29, 4% de los niños escolarizados precisaron refuerzo educativo.
Conclusión
La implementación del Registro en España de pacientes con SHCC ha permitido identificar aspectos relevantes para optimizar sus cuidados, tales como la importancia del estudio genético para el diagnóstico y la estimación de gravedad, la frecuencia elevada de alteraciones oculares y de necesidad de refuerzo educativo, y algunas limitaciones de las técnicas ventilatorias.
Introduction
Congenital Central Hypoventilation Syndrome (CCHS) is a very rare genetic disease. In 2012 the European Central Hypoventilation Syndrome (EuCHS) Consortium created an online patient registry in order to improve care. Aim To determine the characteristics and outcomes of Spanish patients with CCHS, and detect clinical areas for improvement.
Materials and method
An assessment was made on the data from Spanish patients in the European Registry, updated on December 2015. Results The Registry contained 38 patients, born between 1987 and 2013, in 18 hospitals. Thirteen (34.2%) were older than 18 years. Three patients had died. Genetic analysis identified PHOX2B mutations in 32 (86.5%) out of 37 patients assessed. The 20/25, 20/26 and 20/27 polyalanine repeat mutations (PARMs) represented 84.3% of all mutations. Longer PARMs had more, as well as more severe, autonomic dysfunctions. Eye diseases were present in 47%, with 16% having Hirschsprung disease, 13% with hypoglycaemia, and 5% with tumours. Thirty patients (79%) required ventilation from the neonatal period onwards, and 8 (21%) later on in life (late onset/presentation). Eight children (21%) were using mask ventilation at the first home discharge. Five of them were infants with neonatal onset, two of them, both having a severe mutation, were switched to tracheostomy after cardiorespiratory arrest at home. Approximately one-third (34.3%) of patients were de-cannulated and switched to mask ventilation at a mean age of 13.7 years. Educational reinforcement was required in 29.4% of children attending school.
Conclusion
The implementation of the EuCHS Registry in Spain has identified some relevant issues for optimising healthcare, such as the importance of genetic study for diagnosis and assessment of severity, the high frequency of eye disease and educational reinforcement, as well as some limitations in ventilatory techniques
MAREJADAS RURALES Y LUCHA POR LA VIDA, VOL. I:CONSTRUCCIÓN SOCIOCULTURAL Y ECONÓMICA DEL CAMPO.
Este volumen incluye trabajos que abordan temáticas
que demuestran que el campo es una construcción sociocultural, por lo tanto,
el medio rural es diferenciado y está en constante cambio y adaptación a los
procesos globales y locales.
Son 19 trabajos divididos en dos secciones, la primera, denominada Nuevas
dinámicas sociales, económicas y culturales en el medio rural, está compuesta
por 8 capítulos, en esta sección se incluyen aquellos trabajos que analizan de
manera concreta los cambios perceptibles en las relaciones rurales y en las
actividades económicas; procesos como desagrarización y nuevas actividades
económicas son abordados aquí, así como propuestas metodológicas para el
estudio de lo rural considerando los cambios y adaptaciones que se registran
en los territorios.
La segunda sección, Resistencias y alternativas al modelo neoliberal en la
producción agrícola y alimentaria, está integrada por 11 trabajos que abordan
las diversas formas en que los campesinos y productores agrícolas resisten y
se adaptan a los cambios globales y a las modificaciones de política pública,
desde los mercados alternativos hasta la producción de nuevos cultivos que
generan un mercado nuevo a su producción, hasta las resistencias y defensa de
la milpa, las reflexiones que nos ofrecen dan idea de la diversidad de formas
en que la vida campesina se mantiene a pesar de todos los embates.INSTITUTO DE CIENCIAS AGROPECUARIAS Y RURALES (ICAR), UNIVERSIDAD DE GUADALAJARA, EL COLEGIO DE MICHOACÁN A.C., CUCOSTA SUR GRANA, FACULTAD DE ESTUDIOS SUPERIORES ACATLÁN-UNAM, ECOSU
Markov models with lognormal transition rates in the analysis of survival times
Covariates, lognormal distribution, maximum-likelihood estimate, nonhomogeneous Markov process, survival data, 62M05, 62N05,