624 research outputs found

    Density function of random differential equations via finite difference schemes: a theoretical analysis of a random diffusion-reaction Poisson-type problem

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    [EN] A computational approach to approximate the probability density function of random differential equations is based on transformation of random variables and finite difference schemes. The theoretical analysis of this computational method has not been performed in the extant literature. In this paper, we deal with a particular random differential equation: a random diffusion-reaction Poisson-type problem of the form , , with boundary conditions , . Here, alpha, A and B are random variables and is a stochastic process. The term is a stochastic process that solves the random problem in the sample path sense. Via a finite difference scheme, we approximate with a sequence of stochastic processes in both the almost sure and senses. This allows us to find mild conditions under which the probability density function of can be approximated. Illustrative examples are included.This work has been supported by the Spanish Ministerio de Economia y Competitividad grant MTM2017-89664-P. Marc Jornet acknowledges the doctorate scholarship granted by Programa de Ayudas de Investigacion y Desarrollo (PAID), Universitat Politecnica de Valencia.Calatayud, J.; Cortés, J.; Díaz, J.; Jornet, M. (2020). Density function of random differential equations via finite difference schemes: a theoretical analysis of a random diffusion-reaction Poisson-type problem. Stochastics: An International Journal of Probability and Stochastic Processes (Online). 92(4):627-641. https://doi.org/10.1080/17442508.2019.1645849S627641924Berman, A., & Plemmons, R. J. (1994). Nonnegative Matrices in the Mathematical Sciences. doi:10.1137/1.9781611971262Brezis, H. (2011). Functional Analysis, Sobolev Spaces and Partial Differential Equations. doi:10.1007/978-0-387-70914-7Dorini, F. A., Cecconello, M. S., & Dorini, L. B. (2016). On the logistic equation subject to uncertainties in the environmental carrying capacity and initial population density. Communications in Nonlinear Science and Numerical Simulation, 33, 160-173. doi:10.1016/j.cnsns.2015.09.009Hussein, A., & Selim, M. M. (2012). Solution of the stochastic radiative transfer equation with Rayleigh scattering using RVT technique. Applied Mathematics and Computation, 218(13), 7193-7203. doi:10.1016/j.amc.2011.12.088Jost, J. (2007). Partial Differential Equations. Graduate Texts in Mathematics. doi:10.1007/978-0-387-49319-0Kallianpur, G. (1980). Stochastic Filtering Theory. Stochastic Modelling and Applied Probability. doi:10.1007/978-1-4757-6592-2Lord, G. J., Powell, C. E., & Shardlow, T. (2009). An Introduction to Computational Stochastic PDEs. doi:10.1017/cbo9781139017329Strand, J. . (1970). Random ordinary differential equations. Journal of Differential Equations, 7(3), 538-553. doi:10.1016/0022-0396(70)90100-2Villafuerte, L., Braumann, C. A., Cortés, J.-C., & Jódar, L. (2010). Random differential operational calculus: Theory and applications. Computers & Mathematics with Applications, 59(1), 115-125. doi:10.1016/j.camwa.2009.08.061Williams, D. (1991). Probability with Martingales. doi:10.1017/cbo978051181365

    What Matters Most to Patients and Rheumatologists? A Discrete Choice Experiment in Rheumatoid Arthritis

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    Introduction: To determine patient and rheumatologist preferences for rheumatoid arthritis (RA) treatment attributes in Spain and to evaluate their attitude towards shared decision-making (SDM). Methods: Observational, descriptive, exploratory and cross-sectional study based on a discrete choice experiment (DCE). To identify the attributes and their levels, a literature review and two focus groups (patients [P] = 5; rheumatologists [R] = 4) were undertaken. Seven attributes with 2–4 levels were presented in eight scenarios. Attribute utility and relative importance (RI) were assessed using a conditional logit model. Patient preferences for SDM were assessed using an ad hoc questionnaire. Results: Ninety rheumatologists [52.2% women; mean years of experience 18.1 (SD: 9.0); seeing an average of 24.4 RA patients/week (SD: 15.3)] and 137 RA patients [mean age: 47.5 years (SD: 10.7); 84.0% women; mean time since diagnosis of RA: 14.2 years (SD: 11.8) and time in treatment: 13.2 years (SD: 11.2), mean HAQ score 1.2 (SD: 0.7)] participated in the study. In terms of RI, rheumatologists and RA patients viewed: time with optimal QoL: R: 23.41%/P: 35.05%; substantial symptom improvement: R: 13.15%/P: 3.62%; time to onset of treatment action: R: 16.24%/P: 13.56%; severe adverse events: R: 10.89%/P: 11.20%; mild adverse events: R: 4.16%/P: 0.91%; mode of administration: R: 25.23%/P: 25.00%; and added cost: R: 6.93%/P: 10.66%. Nearly 73% of RA patients were involved in treatment decision-making to a greater or lesser extent; however, 27.4% did not participate at all. Conclusion: Both for rheumatologists and patients, the top three decision-making drivers are time with optimal quality, treatment mode of administration and time to onset of action, although in different ranking order. Patients were willing to be more involved in the treatment decision-making process

    The Fusarium oxysporum f. sp. ciceris/Cicer arietinum pathosystem: a case study of the evolution of plantpathogenic fungi into races and pathotypes

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    The use of resistant cultivars is one of the most practical and costefficient strategies for managing plant diseases. However, the efficiency of resistant cultivars in disease management is limited by pathogenic variability in pathogen populations. Knowledge of the evolutionary history and potential of the pathogen population may help to optimize the management of disease-resistance genes, irrespective of the breeding strategy used for their development. In this review, we examine the diversity in virulence phenotypes of Fusarium oxysporum f. sp. ciceris, the causal agent of Fusarium wilt of chickpeas, analyze the genetic variability existing within and among those phenotypes, and infer a phylogenetic relationship among the eight known pathogenic races of this fungus. The inferred intraspecific phylogeny shows that each of those races forms a monophyletic lineage. Moreover, virulence of races to resistant chickpea cultivars has been acquired in a simple stepwise pattern, with few parallel gains or losses. Although chickpea cultivars resistant to Fusarium wilt are available, they have not yet been extensively deployed, so that the stepwise acquisition of virulence is still clearly evident. [Int Microbiol 2004; 7(2):95–104

    Exercises using a touchscreen tablet application improved functional ability more than an exercise program prescribed on paper in people after surgical carpal tunnel release: a randomised trial

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    Question: In people who have undergone surgical carpal tunnel release, do sensorimotor-based exercises performed on the touchscreen of a tablet device improve outcomes more than a conventional home exercise program prescribed on paper? Design: Randomised, parallel-group trial with concealed allocation, assessor blinding, and intention-to-treat analysis. Participants: Fifty participants within 10 days of surgical carpal tunnel release. Intervention: Each participant was prescribed a 4-week home exercise program. Participants in the experimental group received the ReHand tablet application, which administered and monitored exercises via the touchscreen. The control group was prescribed a home exercise program on paper, as is usual practice in the public hospital system. Outcome measures: The primary outcome was functional ability of the hand, reported using the shortened form of the Disabilities of the Arm, Shoulder and Hand (QuickDASH) questionnaire. Secondary outcomes were grip strength, pain intensity measured on a 10-cm visual analogue scale, and dexterity measured with the Nine-Hole Peg Test. Outcomes were measured by a blinded assessor at baseline and at the end of the 4-week intervention period. Results: At Week 4, functional ability improved significantly more in the experimental group than the control group (MD –21, 95% CI –33 to –9) on the QuickDASH score (0 to 100). Although the mean estimates of effect on the secondary outcome also all favoured the experimental group, none reached statistical significance: grip strength (MD 5.6 kg, 95% CI –0.5 to 11.7), pain (MD –1.4 cm, 95% CI –2.9 to 0.1), and dexterity (MD –1.3 seconds, 95% CI –3.7 to 1.1). Conclusion: Use of the ReHand tablet application for early rehabilitation after carpal tunnel release is more effective in the recovery of functional ability than a conventional home exercise program. It remains unclear whether there are any benefits in grip strength, pain or dexterity. Trial registration: ACTRN12618001887268

    A New Mechanism of Sodium Zirconate Formation

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    The objective of this study was to synthesize sodium zirconate (Na2ZrO3) from the thermal decomposition of two reactants; sodium acetate (CH3COONa) and Zirconium(IV) acetylacetonate (Zr(C5H7O2)4). The Na2ZrO3 formation mechanism has not been previously reported as it is shown in this work. Also, the reagents are soluble in ethanol; making it possible to apply the mechanism proposed in a spray pyrolysis process. The solid-state reaction was derived from the thermal decomposition of its precursors through the thermogravimetric analysis techniques (TG). The desired product formation was proven by means of an x-ray diffraction technique while the gaseous by-products of the reaction were analyzed using of the IR spectroscopy method (FTIR). Solid-state reaction has three significant weight losses and the TG technique displays these behaviors. The kinetic reaction study was completed using the determination of the activation energy, the pre-exponential factor and the reaction order of such regions. Finally, it was numerically proven that the chemical reaction behavior is well reproduced using the Arrhenius-type kinetic model. Keywords: Sodium zirconate, Arrhenius equation, solid-state reaction, thermal decomposition

    Inclusión digital de las mujeres en las políticas españolas de la sociedad de la información

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    Proyecto I+D "Las mujeres como tejedoras de las redes sociales: estrategias relacionales e inclusión digital" (referencia: EDU2013-45134-P)Nuestro objetivo es desvelar los diferentes tratamientos de la "inclusión digital de las mujeres" en los Planes Estratégicos relacionados con la Sociedad de la Información en España. El lenguaje narrativo de dichos Planes encuadra la realidad en "marcos" que configuran un determinado contenido mediante la selección y preponderancia de ciertos atributos y argumentos concretos. Nuestro análisis se sustenta en el análisis de contenido de tipo cuantitativo y enfoque fenomenográfico interpretando las diversas concepciones de inclusión digital. El estudio analiza un total de nueve Planes Estratégicos: cuatro de ámbito nacional y cinco de carácter autonómico. Los resultados muestran la necesidad de plantear políticas específicas orientadas a la inclusión digital de las mujeres, ya que el contenido de los planes analizados no las visibiliza de forma explícita. Términos como "igualdad" o "mujeres" son escasamente empleados. Los resultados instan también a una revisión de discursos estereotipados en la redacción de los Planes genéricos.Our aim is to reveal the different treatments of "digital inclusion of women" present in the Strategic Plans documents related to the Information Society in Spain. The narrative language of these Plans encloses the reality in "frameworks" that configure a concrete content through the selection and preponderance of certain attributes and specific arguments. Our analysis is based on a mixed methodology: a quantitative content analysis and a phenomenographic focus for the interpretation of the different conceptions of digital inclusion. The study analyzes a total of nine Strategic Plans: four of national scope and five of autonomic character. The results show the need to propose specific policies aimed at the digital inclusion of women, since the content of the analyzed plans does not explicitly make them visible being. Terms like "equality" or "women" are sparsely used. The results also urge a review of stereotyped speeches in the drafting of generic plans

    Promoting dignified end-of-life care in the emergency department: a qualitative study

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    Background: Preservation of a dying person’s dignity in the emergency department (ED) is fundamental for the patient, his/her relatives and healthcare professionals. The aim of this study was to explore and interpret physicians’ and nurses’ experiences regarding conservation of dignity in end-of-life care in dying patients in the ED. Methods: A qualitative study based on the hermeneutic phenomenological approach, was carried out in the emergency department of two general hospitals. A total of 16 nurses and 10 physicians participated in the study. Data collection included 12 individual in-depth interviews and 2 focus groups. Results: The findings revealed that two themes represent the practices and proposals for the conservation of dignity in the emergency department: dignified care in hostile surroundings and the design of a system focused on the person’s dignity. Conclusion: Dignifying treatment, redesigning environmental conditions, and reorienting the healthcare system can contribute to maintaining dignity in end-of-life care in the ED

    First report of Meloidogyne arenaria parasitizing lettuce in southern Spain

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    During the 2005-2006 autumn to winter lettuce-growing (Lactuca sativa cv. Iceberg) season, severely stunted and yellowing lettuce plants with disease incidence ranging from 80 to 100% were observed in four commercial, fall-sown fields at Almodóvar del Río (Córdoba Province) in southern Spain. Early symptoms consisted of severely reduced growth of the plants that continued with extensive leaf yellowing and the absence of tight-head formation. Attacks by the disease were estimated to cause near complete loss of the crop yields since the lettuce head produced in affected fields were unmarketable. Observations of affected lettuce plants revealed high parasitism of the root system by a root-knot nematode (Meloidogyne sp.) in the main and feeder roots as well as heavy soil infestations by the nematode. The nematode was identified by the female perineal pattern, esterases phenotype, and a sequence-characterized amplified region polymerase chain reaction (SCAR-PCR) technique. Measurements and morphological observations of 20 second-stage juveniles (J2s) (body length = 463 ± 28 μm, dorsal gland orifice from stylet base = 2.8 ± 0.6 μm, stylet length = 10.4 ± 0.5 μm, tail length = 54.4 ± 0.6 μm; hyaline tail terminus = 9.4 ± 0.6 μm) and 10 adult females (stylet length = 14.5 ± 0.7 μm, dorsal gland orifice from stylet base = 4.7 ± 0.5 μm, and perineal pattern with low and rounded dorsal arch with coarse striae) conformed to the description of Meloidogyne arenaria. On the basis of the characteristics of the perineal pattern, the 2-band esterase phenotype, and the 420-bp SCAR fragment, the causal agent was identified as the peanut root-knot nematode M. arenaria. Nematodes were extracted from soil and root samples by standard procedures and their populations quantified. M. arenaria was detected in nearly all soil and root samples assessed, with nematode population densities ranging from 206 to 1,072 eggs and J2s per 5 g of fresh roots. Different Meloidogyne spp. have been reported parasitizing lettuce roots, especially M. hapla in northern areas (2); however, to our knowledge this is the first time that M. arenaria is reported parasitizing lettuce roots in Spain and elsewhere.Peer reviewe

    Towards Compensable SLAs

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    In Cooperative Information Systems, service level agreements (SLA) can be used to describe the rights and obligations of parties involved in the transaction (typically the service consumer and the service provider); amongst other information, SLA could define guarantees associated with the idea of service level objectives (SLOs) that normally represent key performance indicators of either the consumer or the provider. in case the guarantee is under-fulfilled or over-fulfilled SLAs could also define some compensations (i.e. penalties or rewards). in such a context, during the last years there have been important steps towards the automation of the management of SLAs, however the formalization of compensations in SLAs still remains as an important challenge. in this paper we aim to provide a characterization model to create SLAs with compensations; specifically, the main contributions are twofold: (i) the conceptualization of the Compensation Function to express consistently penalties and rewards and (ii) a model for Compensable Guarantees that associate SLOs with Compensation Functions. This formalization models aims to establish a foundation to elaborate tools that could provide an automated support to the modeling and analysis of SLAs with compensations. Additionally, in order to validate our approach, we model and analyze a set of guarantee terms from three real world examples of SLAs and our formalization proves to be useful for detecting mistakes that are ty
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