112 research outputs found

    Rescue of endemic states in interconnected networks with adaptive coupling

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    We study the Susceptible-Infected-Susceptible model of epidemic spreading on two layers of networks interconnected by adaptive links, which are rewired at random to avoid contacts between infected and susceptible nodes at the interlayer. We find that the rewiring reduces the effective connectivity for the transmission of the disease between layers, and may even totally decouple the networks. Weak endemic states, in which the epidemics spreads when the two layers are interconnected but not in each layer separately, show a transition from the endemic to the healthy phase when the rewiring overcomes a threshold value that depends on the infection rate, the strength of the coupling and the mean connectivity of the networks. In the strong endemic scenario, in which the epidemics is able to spread on each separate network -and therefore on the interconnected system- the prevalence in each layer decreases when increasing the rewiring, arriving to single network values only in the limit of infinitely fast rewiring. We also find that rewiring amplifies finite-size effects, preventing the disease transmission between finite networks, as there is a non zero probability that the epidemics stays confined in only one network during its lifetime

    Rescue of endemic states in interconnected networks with adaptive coupling

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    We study the Susceptible-Infected-Susceptible model of epidemic spreading on two layers of networks interconnected by adaptive links, which are rewired at random to avoid contacts between infected and susceptible nodes at the interlayer. We find that the rewiring reduces the effective connectivity for the transmission of the disease between layers, and may even totally decouple the networks. Weak endemic states, in which the epidemics spreads when the two layers are interconnected but not in each layer separately, show a transition from the endemic to the healthy phase when the rewiring overcomes a threshold value that depends on the infection rate, the strength of the coupling and the mean connectivity of the networks. In the strong endemic scenario, in which the epidemics is able to spread on each separate network –and therefore on the interconnected system– the prevalence in each layer decreases when increasing the rewiring, arriving to single network values only in the limit of infinitely fast rewiring. We also find that rewiring amplifies finite-size effects, preventing the disease transmission between finite networks, as there is a non zero probability that the epidemics stays confined in only one network during its lifetime.Fil: Vazquez, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física de Líquidos y Sistemas Biológicos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física de Líquidos y Sistemas Biológicos; Argentina. Consejo Superior de Investigaciones Científicas. Instituto de Física Interdisciplinar y Sistemas Complejos; EspañaFil: Serrano, M. Ángeles. Universidad de Barcelona; España. Institució Catalana de Recerca i Estudis Avancats; EspañaFil: San Miguel, M.. Consejo Superior de Investigaciones Científicas. Instituto de Física Interdisciplinar y Sistemas Complejos; Españ

    Conservation laws for voter-like models on random directed networks

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    18 pages, 2 figures, 1 table.-- ArXiv pre-print: http://arxiv.org/abs/arXiv:0902.1769We study the voter model, under node and link update, and the related invasion process on a single strongly connected component of a directed network. We implement an analytical treatment in the thermodynamic limit using the heterogeneous mean-field assumption. From the dynamical rules at the microscopic level, we find the equations for the evolution of the relative densities of nodes in a given state on heterogeneous networks with arbitrary degree distribution and degree degree correlations. We prove that conserved quantities as weighted linear superpositions of spin states exist for all three processes and, for uncorrelated directed networks, we derive their specific expressions. We also discuss the time evolution of the relative densities that decay exponentially to a homogeneous stationary value given by the conserved quantity. The conservation laws obtained in the thermodynamic limit for a system that does not order in that limit determine the probabilities of reaching the absorbing state for a finite system. The contribution of each degree class to the conserved quantity is determined by a local property. Depending on the dynamics, the highest contribution is associated with influential nodes reaching a large number of outgoing neighbors, not too influenceable ones with a low number of incoming connections, or both at the same time.We acknowledge financial support from MCIN (Spain) and FEDER through project FISICOS (FIS2007-60327); MAS acknowledges support by DGES grant no. FIS2007-66485-C02-01 and the Ramón y Cajal program of the Spanish Ministry of Science, KK acknowledges financial support from Volkswagen Stiftung.Peer reviewe

    Crecimiento de cristales de anglesita y celestina en gel de sílice. Transferencia de masa y criterios de cristalización Sílice. Transferencia de masa y criterios de cristalización

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    En el presente trabajo se analiza la cristalización de Celestina (SrSO,) mediante la técnica del gel de Sílice. El dispositivo experimental consistió en un sistema doble de difusión-reacción. Los reactivos empleados fueron SrCL, y N%S04 (0.5.0.3 y 0.1M. en ambos casos). La testificación experimental de la transferencia de masa y de la evolución del pH en el gel sirvió de vehículo para establecer unos "criterios de cristalización" que. unidos a la sobresaturación, han permitido justificar la posición del primer precipitado. Asimismo, se ha estudiado la influencia de la sobresaturación y de la velocidad de sobresaturación en la morfologíade crecimiento de los cristales de Celestina. El caracter de sistema abierto de la técnica empleada da lugar a que las condiciones de cristalización se modifiquen a lo largo del tiempo y del espacio. Dicha evolución queda reflejada en diferentes estadios morfológicos que se han interpretado de acuerdo con las características fisicoquímicas del medio

    Design and manufacture of a customised temporomandibular prosthesis

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    In this work, design, manufacture and surgical success of a personalised temporomandibular prosthesis is featured. A fused deposition modelling technique and Die forging process constitute the methodology used in a patient who had an amputation in the upper third branch of the mandible, without considering the joint capsule. The implant was designed using a processed resection image of a computational tomography and using the methodology of Özkaya and Nordin. The jaw operating conditions were simulated by the finite element method (FEM). The main considered factors were the morphological geometry of the patient, implant fixation in the first third of the branch, implant fixation on the chin, dental post for placement of the teeth, and the form of the sub-lingual fossa weight optimisation. Special consideration was to preserve the patients facial aesthetics.Peer Reviewe

    Study of scenarios and technical requirements of a social assistive robot for Alzheimer's disease patients and their caregivers

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    Robots have begun to assist elders and patients suffering dementia. In particular, recent studies have shown how robots can benefit Alzheimer's disease (AD) patients. This is a novel area with a promising future but lot of researching needs to be done. The RobAlz project is aimed to assist AD patients and their caregivers by social robots. This project is divided in three phases: the definition of the requirements and scenarios, the development of a new robotic platform, and the evaluation. This work presents the results obtained in the first phase, in which several meetings were conducted with a set of subject-matter experts in the areas of Alzheimer's Disease and social robotics. The meetings were classified according to the application areas they covered: general aspects, safety, entertainment, personal assistance, and stimulation. The meetings ended up with a repertory of scenarios where robots can be applied to Alzheimer's patients and their caregivers at their home or in longterm care facilities. These scenarios present different psychological, social and technical concerns that must be addressed for the design of the robot. In this work we perform an analysis on the scenarios and present the technical requirements for the development of a first robotic prototype. This prototype will be constructed and tested in real environments in the subsequent phases of the RobAlz project.The authors gratefully acknowledge the collaboration of the Spanish Alzheimer Foundation (FAE) and the funds provided by the Spanish Government through the project Aplicaciones de los robots sociales DPI2011-26980, from the Spanish Ministry of Economy and Competitiveness

    Medición de la eficacia en la hemodiafiltración on-line

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    El objetivo de este estudio es estimar la caída del aclaramiento del dializador durante la diálisis medido por OCM y analizar los posibles factores que influyen en ello. Pacientes y métodos: Pacientes de nuestra unidad que estuvieran en tratamiento con hemodiafiltración on-line durante el mes de marzo. Conclusiones: La hemodiafiltración on-line permite tener buenos aclaramientos a lo largo dela sesión. El módulo OCM permite de forma sencilla monitorizar el aclaramiento del dializador a lo largo de la sesión.Dialisia egin bitartean dialisi makinaren argitzea jaistea, OCM bidez neurturikoa, zertan den analizatzea da azterlan honen helburua, baita horretan eragina izan lezaketen faktoreak aztertzea ere. Gure unitatean onlineko hemodiafiltrazio tratamenduan zeuden eriak aztertu genituen hilabeteko aldian. Ondorioztatu dugunez, onlineko hemodiafiltrazioak argitze egokiak izatea ahalbidetzen du saioan zehar eta OCM moduluak ahalbidetu egiten du saioan zeharreko dialisi makinaren argitzea monitorizatzea modu errazean.L'objectif de cette étude est d'estimer la chute de l'éclaircissement du dialyseur durant la dialyse mesuré par OCM et analyser les éventuels facteurs qui influent sur ce processus. Nous analysons les patients de notre unité qui ont été en traitement avec hémodiafiltration on-line durant un mois. Nous en concluons que l'hémodiafiltration on-line permet d'avoir de bons éclaircissements tout aulong de la session et le module OCM permet de monitoriser de façon simple l'éclaircissement du dialyseur tout au long de la session.The objective of this study is to estimate the fall in dialysator clarificationduring dialysis as measured by OCM and to analyse possible factors that may have an influence therein. We analysed the patients in our unit who were undergoing on-line hemodiafiltration treatment during one month. We concluded that on-linehemodiafiltration allows for good clarification throughout the session and that the OCM module allows for easy dialysator monitoring throughout the session

    Relationship Between Self-Perceived Health, Vitality, and Posttraumatic Growth in Liver Transplant Recipients

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    Our objective was to analyze the differences in posttraumatic growth in 240 liver transplant recipients based on two factors. First, self-perceived health: better (Group 1 = G1) and worse (Group 2 = G2). Second, vitality: more (Group 3 = G3) and less (Group 4 = G4). The Posttraumatic Growth Inventory, SF-36 Health Survey (Item 2) and SF-12 Health Survey (vitality dimension) were used. Firstly, analyzing main effects recipients with better (G1) compared to worse (G2) self-perceived health, showed greater posttraumatic growth. Interaction effects were found on essential posttraumatic growth domains such as new possibilities (p = 0.040), personal strength (p = 0.027), and appreciation of life (p = 0.014). Statistically significant differences showed that among transplant recipients with worse self-perceived health (G2), those with more vitality had higher levels on abovementioned posttraumatic growth dimensions. However, in transplant recipients with better self-perceived health (G1) respective dimensions were not significantly influenced by the level of vitality. Among the recipients with less vitality (G4), those with better self-perceived health showed higher scores on abovementioned posttraumatic growth dimensions. We conclude that positive self-perceived health might compensate for a lack of vitality as well as a high level of vitality may compensate for negative self-perceived health regarding the development of crucial aspects of posttraumatic growth after liver transplantation.Ministerio de Economía y Competitividad de España PSI2014-51950-

    Coping strategies in liver transplant recipients and caregivers according to patient posttraumatic growth

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    The purpose of this study was to analyze the differences in coping strategies employed by liver transplant recipients and their family members according to patient posttraumatic growth. Two matched groups of 214 liver transplant recipients and 214 family members were selected. The Posttraumatic Growth Inventory and Brief COPE were used. The most relevant results were: (1) Interactive effects in active coping, support (instrumental and emotional) and acceptance strategies, which were all used more by patients with higher growth levels, while their family members showed no differences in use of these strategies by patient growth level. Furthermore, while a low level of patient growth did not mark differences between them and their caregivers, a high level did, patients employing more active coping and support (instrumental and emotional), (2) In both groups a high level of patient growth was associated with more use of positive reframing and denial than a low one, and (3) Self-blame was employed by patients more than by their caregivers. It was concluded that a high level of posttraumatic growth in liver transplant recipients is associated with more use of healthy coping strategies, basically active coping, instrumental support, and emotional support.Ministerio de Economía y Competitividad PSI2014-51950-

    Spanish adaptation and validation of the Transplant Effects Questionnaire (TxEQ-Spanish) in liver transplant recipients and its relationship to posttraumatic growth and quality of life

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    The valid assessment of the impact of transplantation on psychological well-being is highly relevant to optimize treatment. However, to date there is no standardized instrument available in Spain. The Transplant Effects Questionnaire (TxEQ) evaluates the specific problems associated with organ transplantation, such as worry about transplant, guilt regarding the donor, disclosure of having undergone transplantation, adherence to medical treatment and responsibility toward the donor, family, friends, or medical staff. Against this backdrop the English original version of the TxEQ was translated into Spanish and validated in a sample of 240 liver transplant recipients. Participants also filled in the Posttraumatic Growth Inventory (PTGI), and the 12-Item Short Form Health Survey (SF-12v.2). Confirmatory factor analysis of the TxEQ-Spanish revealed a five-factor structure equivalent to the English original version, and satisfactory internal consistency (Cronbach's alpha: worry α = 0.82, guilt α = 0.77, disclosure α = 0.91, adherence α = 0.82, responsibility α = 0.83). Results showed that better mental quality of life was associated with higher adherence and disclosure, as well as less worry and guilt. Higher posttraumatic growth was significantly associated with worry, guilt, and responsibility. Interestingly, the most powerful predictor of posttraumatic growth was worry. Analysis of variance showed an interaction effect of PTG and mental quality of life on adherence, with medium PTG being associated with significantly stronger adherence in participants with better mental quality of life. In conclusion our study could successfully adapt and validate the Spanish version of the TxEQ in a large sample of liver transplant recipients. Our findings show a complex relationship between emotional reactions to transplantation, mental quality of life, and posttraumatic growth, which give further insight into inner processes supporting psychological well-being and adherence after liver transplantation.Ministerio de Economía y Competitividad de España PSI2014-51950-
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