Measuring absorbed energy in the human auditory system using finite element models: A comparison with experimental results.

BACKGROUND: There are different ways to analyze energy absorbance (EA) in the human auditory system. In previous research, we developed a complete finite element model (FEM) of the human auditory system. OBJECTIVE: In this current work, the external auditory canal (EAC), middle ear, and inner ear (spiral cochlea, vestibule, and semi-circular canals) were modelled based on human temporal bone histological sections. METHODS: Multiple acoustic, structure, and fluid-coupled analyses were conducted using the FEM to perform harmonic analyses in the 0.1-10 kHz range. Once the FEM had been validated with published experimental data, its numerical results were used to calculate the EA or energy reflected (ER) by the tympanic membrane. This EA was also measured in clinical audiology tests which were used as a diagnostic parameter. RESULTS: A mathematical approach was developed to calculate the EA and ER, with numerical and experimental results showing adequate correlation up to 1 kHz. Another published FEM had adapted its boundary conditions to replicate experimental results. Here, we recalculated those numerical results by applying the natural boundary conditions of human hearing and found that the results almost totally agreed with our FEM. CONCLUSION: This boundary problem is frequent and problematic in experimental hearing test protocols: the more invasive they are, the more the results are affected. One of the main objectives of using FEMs is to explore how the experimental test conditions influence the results. Further work will still be required to uncover the relationship between middle ear structures and EA to clarify how to best use FEMs. Moreover, the FEM boundary conditions must be more representative in future work to ensure their adequate interpretation.

Numerical Study of the Plastic Zone at the Crack Front in Cylindrical Aluminum Specimens Subjected to Tensile Loads.

Cylindrical specimens are of great interest in analyzing mechanical elements' behavior and investigating phenomena with biaxial loads. It is necessary to identify the behavior of the crack front along the thickness to interpret these results, which are usually based on the hypothesis of a straight crack and the observation of the outer face of the crack front. Based on the work carried out on compact tension type specimens, this work proposes adapting this methodology to cylindrical specimens, adapting the previous finite element models. Cylindrical specimens provide an asymmetric behavior influenced by the radius, where the CT (compact tensile) specimen can be considered the extreme infinite radius case. Combinations of the load level and radius values help us simulate the crack's behavior under intermediate hypotheses between a plane crack theory and a three-dimensional one. The plastic strain around the crack front will be analyzed as a function of the thickness and the load level applied. The results allow us to validate the numerical methodology and establish the differentiated behaviors of the plastic zones close to the outer and inner radii.

Colorectal cancer: a qualitative study of coping strategies used by survivors, with associated social determinants.

BACKGROUND: Colorectal cancer survivors have to develop coping strategies during the diagnosis and survivorship period. This study aims to identify coping strategies in patients with colorectal cancer, in particular the differences between coping strategies during the disease and throughout survival. It also aims to investigate the impact of some social determinants on coping strategies and critically reflect on the influence of positive psychology. METHODS: Qualitative study with in-depth interviews of a purposive sample of 21 colorectal cancer survivors in Majorca (Spain), developed between 2017-2019. Data was analysed using interpretive thematic analysis. RESULTS: We observed different coping strategies during the stages of disease and survival. However, striving toward acceptance and adaptation when facing difficulties and uncertainty, predominate in both stages. Confrontational attitudes are also considered important, as well as encouraging positive rather than negative feelings, which are considered unhelpful and to be avoided. CONCLUSIONS: Although coping during illness and survival can be classified into common categories (problem and emotion-centred strategies), the challenges of these stages are faced differently. Age, gender and the cultural influence of positive psychology strongly influence both stages and strategies.

Age differences in knowledge, attitudes and preventive practices during the COVID-19 pandemic in Spain.

This study aims at describing the evolution of Spanish population preventive practices during the COVID-19 pandemic of the between January and June 2021, and differences by age group. Data was drawn from the COSMO-Spain online survey, rounds (R) 4, 5 and 6. Multiple linear regression models with preventive practices as dependent variable were performed. Preventive practices (p = 0.001) and concern about coronavirus (p = 0.003) decreased throughout the three rounds, knowledge decreased from R4 to R6 (p = 0.002) and health literacy had a higher value in R6 (p < 0.001). Older the age was associated with higher the frequency of preventive practices, and levels of health literacy and concern about coronavirus (p < 0.001). The regression model showed that, in the 18-29 year group, a greater frequency of preventive practices was associated with being female (ß = 0.20; p < 0.001), greater concern about coronavirus (ß = 0.16; p < 0.018) and frequency of information seeking (ß = 0.24; p < 0.001). For 61 years old and older, a higher frequency of preventive practices was associated with greater concern about coronavirus (ß = 0.21; p < 0.002) and lower pandemic fatigue (ß = - 0.13; p < 0.037). These findings point to the need for effective public health interventions tailored to the characteristics of age population groups.

A Novel Methodology to Obtain the Mechanical Properties of Membranes by Means of Dynamic Tests.

A new, non-destructive methodology is proposed in this work in order to determine the mechanical properties of membrane using vibro-acoustic tests. This procedure is based on the dynamic analysis of the behavior of the membrane. When the membrane is subjected to a sound excitation it responds by vibrating based on its modal characteristics and this modal parameter is directly related to its mechanical properties. The paper is structured in two parts. First, the theoretical bases of the test are presented. The interaction between the sound waves and the membrane (mechano-acoustic coupling) is complex and requires meticulous study. It was broadly studied by means of numerical simulations. A summary of this study is shown. Aspects, such as the position of the sound source, the measuring points, the dimensions of the membrane, the frequency range, and the magnitudes to be measured, among others, were evaluated. The validity of modal analysis curve-fitting techniques to extract the modal parameter from the data measures was also explored. In the second part, an experimental test was performed to evaluate the validity of the method. A membrane of the same material with three different diameters was measured with the aim of estimating the value of the Young's modulus. The procedure was applied and satisfactory results were obtained. Additionally, the experiment shed light on aspects that must be taken account in future experiments.

Slag Substitution as a Cementing Material in Concrete: Mechanical, Physical and Environmental Properties.

A circular economy is a current tenet that must be implemented in the field of construction. That would imply the study of the possibilities of the use of waste generated, for obtaining materials the used in construction as replacements for the raw material used. One of these possibilities is the substitution of the cement by slag, which contributes to the reduction of cement consumption, decreasing CO2 emissions, while solving a waste management problem. In the present paper, different types of concrete made by cement substitution with different type of slags have been studied in order to evaluate the properties of these materials. Cement is replaced by slag from different steel mills, both blast furnace and ladle furnace slag. The percentages of slag substitution by cement are 30%, 40% and 50% by weight. Mechanical, physical and environmental properties have been evaluated. Compressive and flexural strength have been analysed as the main mechanical properties. As far as physical properties go, density and porosity tests were be reported and analysed, and from an environmental point of view, a leachate study was performed. It has been found that some kinds of slag (blast furnace slag) are very suitable as substitutes for cement, providing properties above those of the reference concrete, while other types (ladle furnace slag) could be valid for non-structural applications, contributing in both cases to a circular economy.

Concrete Properties Comparison When Substituting a 25% Cement with Slag from Different Provenances.

Concrete consumption greatly exceeds the use of any other material in engineering. This is due to its good properties as a construction material and the availability of its components. Nevertheless, the present worldwide construction increases and the high-energy consumption for cement production means a high environmental impact. On the other hand, one of the main problems in the iron and steel industry is waste generation and byproducts that must be properly processed or reused to promote environmental sustainability. One of these byproducts is steel slag. The cement substitution with slag strategy achieves two goals: raw materials consumption reduction and waste management. In the present work, four different concrete mixtures are evaluated. The 25% cement substitution is carried out with different types of slag. Tests were made to evaluate the advantages and drawbacks of each mixture. Depending on the origin, characteristics, and treatment of the slag, the concrete properties changed. Certain mixtures provided proper concrete properties. Stainless steel slag produced a fluent mortar that reduced water consumption with a slight mechanical strength loss. Mixtures with ground granulated blast furnace slag properties are better than the reference concrete (without slag).

A study of sound transmission in an abstract middle ear using physical and finite element models.

The classical picture of middle ear (ME) transmission has the tympanic membrane (TM) as a piston and the ME cavity as a vacuum. In reality, the TM moves in a complex multiphasic pattern and substantial pressure is radiated into the ME cavity by the motion of the TM. This study explores ME transmission with a simple model, using a tube terminated with a plastic membrane. Membrane motion was measured with a laser interferometer and pressure on both sides of the membrane with micro-sensors that could be positioned close to the membrane without disturbance. A finite element model of the system explored the experimental results. Both experimental and theoretical results show resonances that are in some cases primarily acoustical or mechanical and sometimes produced by coupled acousto-mechanics. The largest membrane motions were a result of the membrane's mechanical resonances. At these resonant frequencies, sound transmission through the system was larger with the membrane in place than it was when the membrane was absent.

Tympanic-ossicular prostheses and MEMS technology: whats and whys.

CONCLUSIONS: Microelectromechanical systems (MEMS) technology fulfils the requirements of implantable middle ear devices and consequently it becomes an excellent option to design and develop the related transducers. OBJECTIVES: To present a summarized overview of the fundamentals of mechanical technologies in relation to middle ear implants research. MATERIALS AND METHODS: Analysis of the possibilities, limitations and practical applications of MEMS as regards the research, development, transference and fabrication processes. RESULTS: MEMS is a new technology with the potential to develop small integrated mechanical and electronic systems that share many processes of integrated circuits technology and its wide application potential. Middle ear prostheses are essentially special implantable transducers that mimic the properties of the tympano-ossicular system: electromechanical systems that deliver low energy pulses safely and efficiently into the labyrinth fluids. They primarily require: active mechanisms to preclude potential damage levels; minimum energy consumption; adequate dimensions for the middle ear; and biotolerable materials. Additionally, development and translational aspects of the selected technology are of utmost importance in this field.