Finite analysis of stability between modified articular fusion technique, posterior lumbar interbody fusion and posteriorlateral lumbar fusion

Background It is not clear whether modified facet fusion (MFF) is biomechanically different from traditional fusion techniques such as posterior lateral lumbar fusion (PLF) and posterior lumbar interbody fusion (PLIF). Methods In this study, a healthy adult Chinese male volunteer was selected to perform 3D reconstruction of CT image data and simulate the successful fusion of L4–5 MFF, PLF and PLIF, respectively. The motion range of L4–5 segments of the model was simulated under 6 working conditions, including forward flexion, extension, lateral flexion and rotation under normal physiological conditions, and the stability of the three fusion procedures in the pathological segments of the lumbar spine was compared. Results There was no difference in range of motion between MFF model and PLF or PLIF model (P < 0.05). Also, the stiffness of the PLFand the MFF model were comparable (P > 0.05), but were smaller than the PLIF model (P < 0.05). Conclusions MFF provides reliable stability at the lumbar fixation fusion level and does not differ significantly from PLF and PLIF in terms of range of motion.

Agreement between 3D Motion Analysis and Tele-Assessment Using a Video Conferencing Application for Telerehabilitation

The global pandemic of the coronavirus disease 2019 (COVID-19) has highlighted the need for remote healthcare services. This study aimed to evaluate the concurrent validity and reliability of tele-assessment using 3D motion analysis and video conferencing applications. The subjects of this study were 14 Pilates instructors and 14 healthy adults, who repeated five exercises of “side spine stretch,” “bridge,” “toe taps,” “quadruped leg raise,” and “cat and cow” five times each. We performed 3D kinematic analysis with 16 infrared cameras while the subject performed each exercise, and the image captured by one webcam was transmitted to the evaluators through a video conferencing application, and eight raters evaluated the mobility, stability, and symmetry of the movement. The result was then compared with the gold standard 3D motion analysis to evaluate the teleassessment system. The concurrent validity of the data obtained using both methods was analyzed. In addition, the inter-rater reliability of the data from the eight raters was evaluated. As a result, mobility showed excellent (ICC > 0.75, ICCs: intraclass correlation coefficients) or good agreement (ICC = 0.6−0.74) with 3D motion analysis and tele-assessment in all motions. The analysis of stability showed high agreement in general, but it was not significant in “cat and cow.” Symmetry showed moderate agreement only in “bridge” and “toe taps,” showing low agreement compared to other components. In addition, the inter-rater reliability of the tele-assessment showed good agreement (ICC = 0.744). Although there were few components with weaker agreements, the results of this study confirmed that it is a valid and reliable method of tele-assessment using video conferencing applications and showed feasibility as an alternative to the existing face-to-face examination.

Influence of MHD Hybrid Ferrofluid Flow on Exponentially Stretching/Shrinking Surface with Heat Source/Sink under Stagnation Point Region

The numerical investigations of hybrid ferrofluid flow with magnetohydrodynamic (MHD) and heat source/sink effects are examined in this research. The sheet is assumed to stretch or shrink exponentially near the stagnation region. Two dissimilar magnetic nanoparticles, namely cobalt ferrite, CoFe2O4 and magnetite, Fe3O4, are considered with water as a based fluid. Utilizing the suitable similarity transformation, the governing equations are reduced to an ordinary differential equation (ODE). The converted ODEs are numerically solved with the aid of bvp4c solver from Matlab. The influences of varied parameters on velocity profile, skin friction coefficient, temperature profile and local Nusselt number are demonstrated graphically. The analysis evident the occurrence of non-unique solution for a shrinking sheet and it is confirmed from the analysis of stability that only the first solution is the stable solution. It is also found that for a stronger heat source, heat absorption is likely to happen at the sheet. Further, hybrid ferrofluid intensifies the heat transfer rate compared to ferrofluid. Moreover, the boundary layer separation is bound to happen faster with an increment of magnetic parameter, while it delays when CoFe2O4 nanoparticle volume fraction increases.

Discrete biological modeling for the immune response to dengue virus

Dengue infection affects more than half of the world’s population, with 1 billion symptomatic cases identified per year and several distinct genetic serotypes: DENV 1–4. Transmitted via the mosquito bite, the dengue virus infects Langerhans cells. Monocytes, B lymphocytes, and mast cells infected with dengue virus produce various cytokines although it is not clear which ones are predominant during DHF disease. A mathematical model of the Dengue virus infection is developed according to complex dynamics determined by many factors. Starting from a state of equilibrium that we could define as “virus-free” asymptotically stable with a viral reproduction number lower than one which means a very effective action of the innate immune system: it stops the infectious process, the mathematical analysis of stability in the presence of the virus demonstrates that the proposed model is dynamically influenced. Dengue fever affects more than half of the world’s population, with 1 billion symptomatic cases and multiple genetic serotypes confirmed each year, which simulates a network of interactions between the various populations involved without considering the speeds of the processes in question which are indicated in a separate computation. In this research, a hybrid approach of petri nets is utilized to connect the discrete models of dengue.

Analysis of Stability in Couple-Stress Magneto-Fluid

The aim of the present research was to study the effect of magnetic field on the layer of electrically conducting couple-stress fluid heated from below in porous medium. Following the linearized stability theory, Boussinesq approximation and normal mode analysis, the dispersion relation is obtained. The stationary convection, stability of the system and oscillatory modes are discussed. For the case of stationary convection, it is found that the couple-stress parameter and magnetic field have stabilizing effect on the system whereas the medium permeability has a destabilizing effect on the system. The magnetic field introduces oscillatory modes in the system which was non-existent in its absence. A sufficient condition for the non-existent of overstability is also obtained.

Anaerobic Fermentation of Combined Chicken Manure and Straw on a Sequencing Batch Reactor: Analysis of Stability and Numerical Modeling

Anaerobic fermentation experiments were performed using combinations of chicken manure and straw at a temperature of 37±0.5 °C for 70 d. In this investigation, system stability and methane production were analyzed using the Logistic model. According to our results, the highest cumulative methane yield was 292.87 mL/g VS at a straw ratio of 3%. This value was 17.43% higher than the one obtained using pure chicken manure. In addition, a positive correlation between ammonia concentration and content of chicken manure was observed. At the end of the reaction, pH values in the four groups were between 7.0 and 8.0. However, pH in the M2 group was significantly higher than that observed in the rest of the groups. Data also indicated that hydrolase activities were positively correlated with SCOD concentrations. In this context, cellulase activity reached the highest value on day 40. Proteinase activity presented two peaks on days 20 and 40. In the case of lipase, activities and amylase initially increased and later decreased, but the change is small. According to the results of the Logistic model, the highest methane production potential was of 404.41 mL/g VS, at a straw proportion of 3%. In addition, the highest daily methane yield was 6.13 mL/g VS.