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Intervertebral disc (IVD) carries compressive loads and resists the tensile and shear stress, produced during bending and rotational movements. Hence, identifying its mechanical behavior has always encouraged researchers to propose various models for this tissue. Both viscoelastic and hyperelastic behavior have been observed regarding the IVD. Therefore, this study aims at mechanically characterizing the tissue using the existing hyper- and viscoelastic constitutive models and further discuss the best ones. Three stress relaxation tests were performed on ten ovine cervical IVD samples to evaluate their viscoelastic behavior. Models with linear, quasi-linear, and nonlinear behavior were implemented. For the hyperelastic response, another test was carried out using a load with a constant strain rate to fit seven previously suggested hyperelastic constitutive models to our recorded data. All tests were performed as uniaxial compression. Calculations were made using isotropy and incompressibility assumptions. Results approved the nonlinearity of the tissue’s viscoelastic behavior since the linear models predicted divergent responses for different strain inputs. However, modified superposition theory, featuring a time- and strain-dependent relaxation function, was the most accurate model to predict the IVD response at different strain levels. As for hyperelasticity, Mooney-Rivlin, Yeoh, and Veronda-Westmann models fitted the experimental data with higher R² values. [ABSTRACT FROM AUTHOR]

"n Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi;} Background: Rosa damascene has a special role in the Iranian traditional medicine due to its sedative, anticonvulsant and analgesic effects. Regarding its alkaloid, flavonoid and other organic compounds, this plant has always been used to reduce nervousness and treat depression and chronic insomnia. In the present time, synthetic drugs with sedative and anxiolytic properties are used for such problems but due to their side-effects and economic issues, the significance of natural medicines with fewer side-effects is of interest. Considering the importance of sedative and anxiolytic effects of Rosa damascene, we decided to compare this plant with synthetic drugs of the same properties."n"nMethods: Two different groups of male Wistar rats received either Rosa damascene extract in doses of 150, 300, 450 mg/kg or Diazepam and dimethyl sulphoxide in doses of 1.2 mg/kg intraperitoneally 30 minutes before assessing the sleep duration, sedation and preanesthetic effects induced by intraperitoneal ketamine, 40 mg/kg. The anti-anxiety effect was evaluated by using an elevated plus maze and a rota rod."n"nResults: The results showed a meaningful increase in the period of sleep induced by Ketamine (P≤0.01) and also a meaningful increase in time spent at the open arms of the device in the group receiving Rosa damascene extract (P≤0.01)."n"nConclusion: The results showed that the Rosa damascene extract dose 450mg/kg has sedative, preanesthetic and anxiolytic effects (P≤0.01).

The responses of nonlinear vibrating systems are investigated analytically using Homotopy Perturbation Method (HPM). To demonstrate the validity of the proposed method, the results obtained by HPM have been depicted graphically and have been compared with those of the exact solution. A clear conclusion can draw from the numerical results that the method provides highly accurate solutions to the discussed problem. Key words: Homotopy-Perturbation Method (HPM), nonlinear vibrating systems, nonlinear dynamic equations, INTRODUCTION Engineering problems especially vibrating systems, often described by their governing equations in the form of differential equations, either linear or nonlinear. Except a limited number, in most cases, these [...]

Background: Health information systems are integral tools that strengthen (and ideally drive) decision-making related to delivery of healthcare services and health outcomes in lower-income countries. However, often these data systems remain underutilized in local healthcare facilities. In sub-Saharan Africa, many countries are seeing an increasing number of facility-based births but not necessarily a corresponding improvement in outcomes, indicating that maternal and newborn health is an area in which better health information is needed to inform quality improvement initiatives. The purpose of this project was to design, implement, and evaluate a localized HIS to build capacity for quality improvement and research in maternal and newborn health at Muhimbili National Hospital in Dar es Salaam, Tanzania. Methods: Through a collaborative partnership between Muhimbili National Hospital and Emory University, a data collection system using REDCap was developed to provide sustainable, high-quality data on in-patient maternal and newborn health services. Called the Obstetric and Neonatal Database, this project was led and implemented by nurses at MNH with support from staff obstetricians, IT personnel, and the hospital's Training, Research, and Consultancy Unit. Four months after its launch, we conducted a mixed-methods evaluation that used quantitative methods to assess data capture and quality, and qualitative methods to elicit perceptions and experiences of users. Results: The project demonstrated significant successes overall and continues to be used as a means of assessing quality on the maternity wards today. Although data accuracy was high, the evaluation revealed large discrepancies in data capture; specifically, data from labor and surgical wards were >97% complete versus only about 20% complete in postnatal and newborn wards. This inconsistency is attributed to differing degrees of hands-on training and efforts to promote ownership and investment among nursing staff. On the other hand, most nurses overwhelmingly reported positive experiences with the database, describing unanticipated benefits that ranged from enhanced workflow efficiency to improved data security to updated technology-related skills. Conclusion: To effectively provide local health facilities with critical information for evaluating and improving outcomes, health management information systems must be closely tailored to the needs of specific contexts and for the benefit of all users. [ABSTRACT FROM AUTHOR]

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This paper investigated the chemically reactive radiating flow by using a two‐dimensional Darcy‐Forchheimer model with the convectively heated plate. The nonlinear thermal radiation is described by Joule heating and heat generation. Also, Darcy‐Forchheimer equation is related to porous medium flows. For the solution of equations, we used the numerical method. Further, more physical interpretation of the parameters was demonstrated with figures. It is found that an increase in the Prandtl number had a direct effect on the Nusselt number and temperature, whereas the opposite scenario was observed in the Eckert number. [ABSTRACT FROM AUTHOR]

Background: Obstructive sleep apnea (OSA) is a common disorder with multifactorial pathogenesis. It has been proposed that rostral fluid displacement contributes to the pathogenesis of OSA. We hypothesized that if fluid shift is an important factor in OSA, then it would be more severe during the second one-half of the night when there is maximally displaced fluid rostrally.Methods: We prospectively enrolled 135 patients who underwent polysomnography. Neck and leg circumferences were measured to determine rostral fluid shift in recumbent position before and after sleep study. Breathing disturbance index (BDI) was derived for non-rapid eye movement sleep during the first and second one-half of the night in the same position.Results: Sixty-five patients with demonstrable rostral fluid shift overnight were included in the analyses. Thirty-two (age, 52.5 ± 2.2 years) had OSA with a mean BDI of 27 ± 3/h (range, 5-80/h), whereas the other 33 with mainly upper airway resistance syndrome (age, 48.7 ± 2.4 years) had a BDI of 13 ± 2/h. Patients in both groups were obese. There was a statistically significant increase in neck circumference in patients with OSA (41.5 ± 0.8 to 42.6 ± 0.7 cm, P < .0001) and without OSA (38.6 ± 0.6 to 40.2 ± 0.6 cm, P < .0001) overnight, with concomitant decreases in leg circumferences. In spite of the fluid shift, BDI did not change (18 ± 3/h and 20 ± 3/h) between the first and second one-half of the night.Conclusions: There is a significant fluid shift rostrally to the neck overnight in patients with and without OSA. However, this fluid shift is not associated with worsening of OSA, thus making it unlikely that fluid displacement is a contributing factor in the pathogenesis or severity of OSA. [ABSTRACT FROM AUTHOR]