Bifurcation analysis of residually stressed neo-Hookean and Ogden electroelastic tubes.

The conditions for bifurcation of a circular cylindrical tube of elastic material subjected to combined axial loading and internal pressure are well known and are frequently used as a reference in related works. The present paper takes the theory further by considering a residually stressed circular cylindrical dielectric tube subjected to a combination of internal or external pressure, axial load and radial electric field. We examine axisymmetric incremental deformations and increments in the electric displacement superimposed on a known finitely deformed and residually stressed configuration in the presence of an electric field. The governing equations and boundary conditions are first obtained in general form and then specialized for the neo-Hookean and Ogden electroelastic models. The system of equations is solved numerically for different values of charge density and radial and circumferential residual stresses, and the results are compared with the purely elastic case. The bifurcation curves are presented as the azimuthal stretch on the inner surface versus the axial stretch together with the corresponding zero pressure curves. This article is part of the theme issue 'The Ogden model of rubber mechanics: Fifty years of impact on nonlinear elasticity'.

What do urban and rural hotel managers say about the future of hotels after COVID-19? The new meaning of safety experiences.

The pandemic crisis has caused a change in tourism trends that affect the way hotels are managed. In accordance with the United Nations (2020), hotels must guarantee safe experiences for customers by incorporating sustainability measures. Collaboration between health and tourism authorities and the tourism industry is key. To test this proposal among hotels in Spain, 3 online focus groups and 25 personal interviews with 36 urban and 28 rural hotels were held in order to define the indicators. The questionnaire was applied to a sample of 475 urban hotels out of 443 rural hotels. The conclusions were: 1.) While in urban areas the testing protocols, especially for workers, are followed by most hotels, in rural areas hotel managers do not consider it as a priority in daily activity due to the reduced contact they have. 2.) A change in trends in the sustainable management of both rural and urban hotels is justified. 3.) Urban and rural hotels are more likely to incorporate collaborative strategies with tourism and health authorities to reduce the negative impact of COVID-19. According to the estimates of the hotels, the implementation of these measures would help to start the recovery process of the hotel industry.

The role of malignant tissue on the thermal distribution of cancerous breast.

The present work focuses on the integration of analytical and numerical strategies to investigate the thermal distribution of cancerous breasts. Coupled stationary bioheat transfer equations are considered for the glandular and heterogeneous tumor regions, which are characterized by different thermophysical properties. The cross-section of the cancerous breast is identified by a homogeneous glandular tissue that surrounds the heterogeneous tumor tissue, which is assumed to be a two-phase periodic composite with non-overlapping circular inclusions and a square lattice distribution, wherein the constituents exhibit isotropic thermal conductivity behavior. Asymptotic periodic homogenization method is used to find the effective properties in the heterogeneous region. The tissue effective thermal conductivities are computed analytically and then used in the homogenized model, which is solved numerically. Results are compared with appropriate experimental data reported in the literature. In particular, the tissue scale temperature profile agrees with experimental observations. Moreover, as a novelty result we find that the tumor volume fraction in the heterogeneous zone influences the breast surface temperature.

Understanding the knowledge structure and the value creation process of the metaverse.

The metaverse is a digital space that empowers users to interact socially, using new and specific technologies, to generate value and co-create experiences. This paper provides a framework for organising the themes discussed in pioneering literature. An adaptation of the PRISMA process was used to explain the methodology applied. The results showed that more than 84 % of studies on the metaverse have been published since 2020. Technologies such as augmented reality and artificial intelligence are positioned as the basic themes, and decision-making and human-machine interface are emerging themes. This paper constitutes an original contribution as it also presents the highlights and structure of the main themes on metaverse. Additionally, it develops an analytical framework for understanding the metaverse value creation. Therefore, this paper represents a starting point for a reflection on the applications of the metaverse that can contribute to the achievement of productive and valuable progress in various fields of research.

The impact of vascular volume fraction and compressibility of the interstitial matrix on vascularised poroelastic tissues.

In this work we address the role of the microstructural properties of a vascularised poroelastic material, characterised by the coupling between a poroelastic matrix and a viscous fluid vessels network, on its overall response in terms of pressures, velocities and stress maps. We embrace the recently developed model (Penta and Merodio in Meccanica 52(14):3321-3343, 2017) as a theoretical starting point and present the results obtained by solving the full interplay between the microscale, represented by the intervessels' distance, and the macroscale, representing the size of the overall tissue. We encode the influence of the vessels' density and the poroelastic matrix compressibility in the poroelastic coefficients of the model, which are obtained by solving appropriate periodic cell problem at the microscale. The double-poroelastic model (Penta and Merodio 2017) is then solved at the macroscale in the context of vascular tumours, for different values of vessels' walls permeability. The results clearly indicate that improving the compressibility of the matrix and decreasing the vessels' density enhances the transvascular pressure difference and hence transport of fluid and drug within a tumour mass after a transient time. Our results suggest to combine vessel and interstitial normalization in tumours to allow for better drug delivery into the lesions.

Stress at Work: Can the Spiritual Dimension Reduce It? An Approach From the Banking Sector.

Stress at work motivated by pressures and labour control can alter the behaviour of workers. Since the 2008 economic crisis, banking in Spain has suffered a series of massive lay-offs to adjust to the new market situation. This new financial restructuring has meant greater labour pressure to achieve the required results. Faced with this adversity, employees have experienced greater stress at work. This work analyses the effect of reinforcing employees' spiritual dimension to transcend and correctly manage work pressure and stress at work. In so doing, 601 employees from 294 financial entities of five large IBEX banks participated in this pilot project. Through a participatory methodology based on a review of the literature, the study indicators have been delimited. The data obtained have been treated using the SEM-PLS method. The results propose the incorporation of a series of tools to reinforce values and transcendent employee behaviour.

Safety and Health Measures for COVID-19 Transition Period in the Hotel Industry in Spain.

The health crisis caused by the outbreak of the COVID-19 disease has devastated the worldwide hospitality sector. The current situation has led many countries to implement drastic rules to stop the spread of the virus. According to the Spanish health authority decisions need to be made in the context of uncertainty and lack of knowledgeable experiences through a gradual and asymmetric de-escalation process planned in four phases. Although the vast majority of studies refer to economic risks and impacts on tourist flows and economic income, few of them explicitly investigates safety and health measures that hotel managers should implement to their customers. Over a population of 12,740 hotels, 823 Spanish hotel managers have been involved in a participatory study. With the aim of assessing the actions taken to stop the spread of the virus, empirical research was implemented. A model presented four variables and 13 indicators which have been previously tested among hotel managers in the tourism sector. Five conclusions are drawn from the hypotheses: (1) Mass testing surveillance in customers and employees should be quick, affordable, and homogeneous throughout the European Union. (2) Training measures need to be taken by both public authorities and the private sector to reach a knowledgeable crisis management team with high commitment to the customer's health and safety. (3) Protocols established by public authorities should be observed and adjusted gradually not only in hotels but also in tourist arrivals. (4) Healthy measures need to be periodically updated. (5) Each hotel should set up a surveillance process to guarantee the safety to their customers.

Residually Stressed Fiber Reinforced Solids: A Spectral Approach.

We use a spectral approach to model residually stressed elastic solids that can be applied to carbon fiber reinforced solids with a preferred direction; since the spectral formulation is more general than the classical-invariant formulation, it facilitates the search for an adequate constitutive equation for these solids. The constitutive equation is governed by spectral invariants, where each of them has a direct meaning, and are functions of the preferred direction, the residual stress tensor and the right stretch tensor. Invariants that have a transparent interpretation are useful in assisting the construction of a stringent experiment to seek a specific form of strain energy function. A separable nonlinear (finite strain) strain energy function containing single-variable functions is postulated and the associated infinitesimal strain energy function is straightforwardly obtained from its finite strain counterpart. We prove that only 11 invariants are independent. Some illustrative boundary value calculations are given. The proposed strain energy function can be simply transformed to admit the mechanical influence of compressed fibers to be partially or fully excluded.

Asymptotic Homogenization Applied to Flexoelectric Rods.

In this manuscript, the equilibrium problem for a flexoelectric one-dimensional composite material is studied. The two-scales asymptotic homogenization method is used to derive the homogenized formulation of this problem. The manuscript offers a step-by-step methodology to derive effective coefficients and to solve local problems. As an illustrative example, results reported in the literature for piezoelectric composites are obtained as a particular case of the formulation derived here. Finally, three flexoelectric/piezoelectric composites are studied to illustrate the influence of the flexoelectric property on the effective coefficients and the global behavior of the structure.

MOOCs, an innovative alternative to teach first aid and emergency treatment: A practical study.

The fast and constant evolution of Massive Open Online Courses (MOOCs) has gained the attention of the educational community, achieving widespread popularity among many universities. However, there is very little research on the use and acceptance of MOOCs by students in disciplines such as health and medicine. The principal focus of this study is to explore the behavior of students from a MOOC on Health Emergencies, analyzing the completion and drop-out rates. The data were collected from three self-administered questionnaires; the first identified general demographic information and the students' learning preferences, the second determined the level of MOOC adoption and the level of identification and satisfaction the students had with the course content, and the third measured the completion and drop-out rates. The MOOC had more than 2114 registered participants. The enrolled students showed high levels of commitment and motivation to learn about this topic through a varied of innovative educational resources, such as videos, learning activities, and interactive animations. In general, the participants expressed their desire to continue learning with this type of methodology. However, the results also showed important issues to be considered in the design and development of a MOOC of these characteristics.

Technical efficiency and organ transplant performance: a mixed-method approach.

Mixed methods research is interesting to understand complex processes. Organ transplants are complex processes in need of improved final performance in times of budgetary restrictions. As the main objective a mixed method approach is used in this article to quantify the technical efficiency and the excellence achieved in organ transplant systems and to prove the influence of organizational structures and internal processes in the observed technical efficiency. The results show that it is possible to implement mechanisms for the measurement of the different components by making use of quantitative and qualitative methodologies. The analysis show a positive relationship between the levels related to the Baldrige indicators and the observed technical efficiency in the donation and transplant units of the 11 analyzed hospitals. Therefore it is possible to conclude that high levels in the Baldrige indexes are a necessary condition to reach an increased level of the service offered.

Atrial fibrillation and quality of life related to disease and treatment: focus on anticoagulation.

Anticoagulation therapy is essential to reduce the risk of stroke in patients with atrial fibrillation. Traditionally, clinical trials have focused only on determining the efficacy and safety of anticoagulation but not on quality of life. In the last few years there has been a growing interest in determining the quality of life of patients treated with oral anticoagulation. In fact, specific tools that can evaluate quality of life related to atrial fibrillation and anticoagulation have been developed. Vitamin K antagonists have been shown to be effective in the prevention of thromboembolic complications. However, the use of vitamin K antagonists implies changes in behavior and lifestyle modifications that may have a negative impact on the quality of life. It has been suggested that self-monitoring of international normalized ratio could improve this impact. On the other hand, as new oral anticoagulants overcome these limitations, they may improve quality of life related with anticoagulant therapy. Unfortunately, although encouraging, the clinical experience with them is still quite limited.

Gastroparesia aguda intraprocedimiento durante crioablación de venas pulmonares / Acute intraprocedural gastroparesis during pulmonary vein cryoablation

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Programación del desfibrilador automático implantable / Programming implantable cardioverter–defibrillators

Los desfibriladores automáticos modernos incluyen entre sus funciones la estimulación antibradicardia, la cardioversión de baja energía y la desfibrilación de alta energía. Tienen, además, criterios adicionales de detección para discriminar en lo posible las arritmias ventriculares de las de origen supraventricular. Son multiprogramables y pueden ser programados para actuar en diferentes zonas de frecuencia de taquicardia, lo que permite tratar de forma diferente cada taquicardia ventricular (TV) que pueda tener un paciente. Esto es particularmente útil en pacientes que presentan TV con ciclos diferentes. La estimulación antitaquicardia disminuye la necesidad de cardioversión o desfibrilación en pacientes con TV. Se han comparado diferentes algoritmos de estimulación con resultados similares. En este capítulo de la monografía se analizan dichos algoritmos y su mejor programación, la necesidad de estimulación antibradicardia y la selección del modo de estimulación, y cómo evitar en lo posible las terapias inapropiadas debidas a arritmias supraventriculares (AU)

Among other functions, modern implantable cardioverter-defibrillators (ICDs) are able to perform antibradycardia pacing, low-energy cardioversion, and highenergy defibrillation. In addition, they can implement a range of different arrhythmia detection criteria that enable them to discriminate, when possible, between ventricular and supraventricular tachycardias. The devices can be programmed in a range of different ways. They can be set to respond differently according to specific tachycardia frequency ranges, thereby enabling each form of tachycardia experienced by the patient to be treated differently. This capability is particularly useful in patients who present with ventricular tachycardias with a number of different cycle lengths. Antitachycardia pacing reduces the need for cardioversion or defibrillation in patients with ventricular tachycardias. Comparison of different pacing algorithms has shown that they give similar results. This part of the monograph contains reviews of the efficacy of these algorithms and how they can be better programmed, of the need for antibradycardia pacing and selection of the most appropriate pacing mode, and of how the administration of inappropriate shocks in response to supraventricular arrhythmias can be avoided (AU)