Evaluation of Biaxial Mechanical Properties of Aortic Media Based on the Lamellar Microstructure

Evaluation of the mechanical properties of arterial wall components is necessary for establishing a precise mechanical model applicable in various physiological and pathological conditions, such as remodeling. In this contribution, a new approach for the evaluation of the mechanical properties of aortic media accounting for the lamellar structure is proposed. We assumed aortic media to be composed of two sets of concentric layers, namely sheets of elastin (Layer I) and interstitial layers composed of mostly collagen bundles, fine elastic fibers and smooth muscle cells (Layer II). Biaxial mechanical tests were carried out on human thoracic aortic samples, and histological staining was performed to distinguish wall lamellae for determining the dimensions of the layers. A neo-Hookean strain energy function (SEF) for Layer I and a four-parameter exponential SEF for Layer II were allocated. Nonlinear regression was used to find the material parameters of the proposed microstructural model based on experimental data. The non-linear behavior of media layers confirmed the higher contribution of elastic tissue in lower strains and the gradual engagement of collagen fibers. The resulting model determines the nonlinear anisotropic behavior of aortic media through the lamellar microstructure and can be assistive in the study of wall remodeling due to alterations in lamellar structure during pathological conditions and aging

Assessment of different quit smoking methods selected by patients in tobacco cessation centers in Iran

Background: Health systems play key roles in identifying tobacco users and providing evidence-based care to help them quit. This treatment includes different methods such as simple medical consultation, medication, and telephone counseling. To assess different quit smoking methods selected by patients in tobacco cessation centers in Iran in order to identify those that are most appropriate for the country health system. Methods: In this cross-sectional and descriptive study, a random sample of all quit centers at the country level was used to obtain a representative sample. Patients completed the self-administered questionnaire which contained 10 questions regarding the quality, cost, effect, side effects and the results of quitting methods using a 5-point Likert-type scale. Percentages, frequencies, mean, T-test, and variance analyses were computed for all study variables. Results: A total of 1063 smokers returned completed survey questionnaires. The most frequently used methods were Nicotine Replacement Therapy (NRT) and combination therapy (NRT and Counseling) with 228 and 163 individuals reporting these respectively. The least used methods were hypnotism (n = 8) and the quit and win (n = 17). The methods which gained the maximum scores were respectively the combined method, personal and Champix with means of 21.4, 20.4 and 18.4. The minimum scores were for e-cigarettes, hypnotism and education with means of 12.8, 11 and 10.8, respectively. There were significant differences in mean scores based on different cities and different methods. Conclusions: According to smokers′ selection the combined therapy, personal methods and Champix are the most effective methods for quit smoking and these methods could be much more considered in the country health system

Quit smoking experts′ opinions toward quality and results of quit smoking methods provided in tobacco cessation services centers in Iran

Background: One of the core responsibilities of health system is to treat tobacco dependence. This treatment includes different methods such as simple medical consultation, medication, and telephone counseling. To assess physicians′ opinions towards quality and result of different quit smoking methods provided in tobacco cessation services centers in Iran. Methods: In this cross-sectional and descriptive study, random sampling of all quit centers at country level was used to obtain a representative sample size of 100 physicians. Physicians completed a self-administered questionnaire which contained 10 questions regarding the quality, cost, effect, side effects, and the results of quitting methods using a 5-point Likert-type scale. Percentages, frequencies, mean, T-test, and variance analyses were computed for all study variables. Results: Most experts preferred to use combination quit smoking methods and then Nicotine Replacement Therapy (NRT) with 26 and 23, respectively. The least used methods were quit line and some methods without medication with 3 cases. The method which gained the maximum scores were telephone consultation, acupuncture, Willpower, Champix, combined method, and Interactive Voice Response (IVR) with the mean of 23.3, 23, 22.5, 22, 21.7 and 21.3, respectively. The minimum scores were related to e-cigarette, some methods without medication, and non-NRT medication with the mean of 12.3, 15.8 and 16.2, respectively. There were no significant differences in the mean of scores based on different cities (P = 0.256). Analysis of variance in mean scores showed significant differences in the means scores of different methods (P < 0.000). Conclusions: According to physicians acupuncture, personal methods and Champix are the most effective methods and these methods could be much more feasible and cost effective than other methods

The Distributed Lambda (λ) Model (DLM): A 3-D, Finite-Element Muscle Model Based on Feldman's λ Model; Assessment of Orofacial Gestures

International audiencePurpose: The authors aimed to design a distributed Lambda model (DLM), which is well-adapted to implement three-dimensional (3-D) Finite Element descriptions of muscles. Method: A muscle element model was designed. Its stress-strain relationships included the active force-length characteristics of the Lambda model along the muscle fibers, together with the passive properties of muscle tissues in the 3-D space. The muscle element was first assessed using simple geometrical representations of muscles in form of rectangular bars. Then, it was included in a 3-D face model, and its impact on lip protrusion was compared with the impact of a Hill-type muscle model. Results: The force-length characteristic associated with the muscle elements matched well with the invariant characteristics of the Lambda model. The impact of the passive properties was assessed. Isometric force variation and isotonic displacements were modeled. The comparison with a Hill-type model revealed strong similarities in terms of global stress and strain. Conclusion: The DLM accounted for the characteristics of the Lambda model. Biomechanically no clear differences were found between the DLM and a Hill-type model. Accurate evaluations of the Lambda model, based on the comparison between data and simulations, are now possible with 3-D biomechanical descriptions of the speech articulators because to the DLM