Background and aim: Unstable shoes usually are used in work environments to reduce work-related disorders. The purpose of this study was to investigate the immediate effects of using unstable shoes on the activity of trunk muscles during load lifting.Material and Methods: This semi-experimental study included 15 able-bodied men. Activation of rectus abdominis, external oblique, internal oblique, multifidus, erector spinae, latissimus dorsi, quadratus lumborum, and gluteus medius muscles in the dominant side of the body was recorded during load lifting in barefoot condition and with typical shoes, and unstable shoes on. We used analysis of variance with repeated measure test for data analysis (a=0.05).Results: The results of this study showed significant decrease in the mean normalized muscle activation of the rectus abdominis, internal oblique, and quadratus lumborum during load lifting and also decreased normalized peak muscle activation of the rectus abdominis, quadratus lumborum, and erector spinae as well as an increase in the normalized peak muscle activation of multifidus with unstable shoes on (P<0.05). Morover, with unstable shoes on, we found significant increases in the mean frequency values of external oblique, internal oblique, multifidus, and erector spinae muscles, compared to barefoot condition and with typical shoes on (P<0.05). Also, use of unstable shoes compared to the two other conditions decreased cocontraction level of the rectus abdominis/ erector spinae, rectus abdominis/ multifidus, internal oblique/ erector spinae, and external oblique/ multifidus muscles (P<0.05).Conclusion: Considering decreased activation and co-contraction levels of the selected trunk muscles use of unstable shoes may have some beneficial effects such as reduction of stress on the lumbar vertebrae and prevention of various injuries to the lumbar region such as low back pain. However, more investigations are needed in order to provide more precise results.

Introduction: Several studies have demonstrated the postural control alterations in patients with low back pain. However, the difference in center of pressure (COP) parameters in the body sway in unstable conditions is relatively unknown in these patients. Therefore, the aim of the present study was to investigate the effects of unstable load and support surface on postural control in chronic low back pain (CLBP) patients.Materials and methods: CLBP patients (n=20) (mean age 31.30 years and mean BMI 25.20 kg/m2) and 20 healthy subjects (mean age 30.00 years and mean BMI 24.12 kg/m2) were asked to hold a load weighing 10 percent of their body weight while standing. Experimental conditions were manipulated based on stability of load (stable or unstable) and support surface (firm or foam). Using a force plate, COP sway parameters including sway amplitude (and its standard deviation) and sway velocity (and its standard deviation) in anteroposterior (AP) and mediolateral (ML) directions were measured.Results: Patients with CLBP exhibited less AP sway amplitude compared to control subjects (P=0.03). Furthermore, they had less ML sway velocity while holding the unstable load (P=0.05) and more ML sway amplitude while standing on foam (P=0.04).Conclusion: In compare to healthy subjects, patients with CLBP demonstrated a different pattern of postural control during instability of load and support surface. In these conditions, altered proprioception and stiffening strategy can increase the risk of spine injuries.

After the constitutional revolution and especially after the movement of Nima Yooshij in interpretation of the fundamental Persian poet and the various streams since the twentieth decade such formations have been emerged with approximately different components and indices, however, since the formation and style of his works have been different, the language and contents could not be distinguished via any boundary generally not finalized.Such streams often take place in the content of the poets, as the most famous streams include: new wave, pure poet, volume poet, movement poet, post-Nima poet as well as the Ghazal, modern, postmodern, form, word, pen, etc. format and eventually due to the divergence with the poet of Iran and the interest of Iranian people into the feasible achievement.In the present article, such streams and features and their poems have been discussed.

Background: Intertrochanteric fractures continue to be one of the common orthopaedic injuries with heavy economic or / and social burden on the families and society. Internal fixation and early mobilization in the standard of care for these fractures. DHS is widely used, and is highly successful for the fixation of the stable types but performs less well with unstable fracture patterns and has relatively higher failure rates. Proper positioning of the lag screw in central and deep part of the femoral head is crucial. It remains unclear if the presumed theoretical benefits of the intramedullary implant and lateral stabilizing plate warrant the additional expenses.

Here we concern ourselves with the derivation of a system of evolution equations for slowly varying amplitude of a baroclinic wave packet. The self-induced transparency, sine-Gordon, and nonlinear Schrodinger equations, all of which possess soliton solutions, each arise for different in viscid limits. The presence of viscosity, however, alters the form of the evolution equations and changes the character of the solutions from highly predictable soliton solutions to unpredictable chaotic solutions. When viscosity is weak, equations related to the Lorenz attractor equations obtain, while for strong viscosity the Ginzburg-Landau equation obtain.

In this article closed-loop behavior of non-linear unstable systems using model predictive control has been investigated. Closed-loop stability in presence of input constraint is discussed and related theorems have been stated. Two cases are considered. First it is assumed that all states are available and thereafter stability based on application of observer has been investigated. Since closed-loop performance is affected by the observer rate of convergence, in the second case, a high gain observer has been used and effect of observer gain on the system performance has been demonstrated.

The purpose of the present study was to examine the relationship between stable (intelligence and personality) and unstable (Academic self-efficacy, academic engagement and academic skills) psychological factors in predicting the academic buoyancy. 400 students (200 girls and 200 boys) were selected from among high school students in Shahrekord through random cluster sampling who answered the research questionnaires of intelligence, personality, academic skills, academic engagement and academic self-efficacy. The data were analyzed by statistical methods including Pearson correlation coefficient and multivariate regression using SPSS-21. The findings revealed that in case of stable factors, academic buoyancy may be predicted negatively by neuroticism and positively by extraversion; while the unstable psychological factors, academic skills and academic engagement may predict the academic buoyancy. Therefore, it can be concluded that the academic buoyancy is affected by some stable and unstable psychological factors and both factors must be considered in order to enhance the academic buoyancy.