Displacement Of Center Research Articles

Дослідження дефектів поверхні труб із недеформованої безперервнолитої заготовки

Defects of outer and inner surfaces of hot-rolled tubes of various steel grades and sizes manufactured on tube-rolling unit with a continuous mill (TPA 30-102) at Interpipe Nikotube LLC from a nondeformed continuously cast billets produced by MZ Dniprostal LLC have been studied. Characteristic genetic and morphological signs of defects were revealed which makes it possible to reliably classify them, identify cause of defect formation and recommend measures to eliminate them. Defects on the outer and inner surfaces of tubes are of metallurgical origin and associated with quality of initial continuously cast billets (a consequence of violation of the smelting and continuous casting technology). Defects on the inner surface of tubes were caused on defects in the axial zone of original billets (unacceptable porosity, looseness, chemical inhomogeneity, liquation stripes and cracks, etc.) and are classified as steel-smelting films and bulges. It was found that displacement of the thermal center of crystallization (a feature of the machines for continuous steel casting of curvilinear type) had an additional negative effect on quality of the inner surface of the studied tubes. Defects on the outer surface of tubes are tears of burning in places of accumulation of low-melting inclusions and their eutectics, as well as steel-smelting scabs on rolled dirt and gas bubbles. Likelihood of formation of scabs on outer surface of the studied tubes over rolled crust introversions is not excluded. The study results will allow manufacturers to reliably classify defects, promptly reject tubes with unacceptable defects of metallurgical origin and minimize supply of low-quality products to consumers. These results will later be included in the classifier of defects in tubes manufactured on the TPA 30-102 unit from nondeformed continuously cast billets. The results of the study of natural signs of defects of metallurgical origin in the tube surface will be useful for elaboration of measures aimed at improvement of the technology of manufacturing initial tube billets. Keywords: tube surface defects, continuously cast billets, microstructure, rolled contamination, low-melting inclusions, eutectic, gas bubbles, decarburization, liquation.

Comparison of laminate thickness on the low velocity impact behaviors for Z-pinned composite laminates

The Z-pinning technique can enhance the delamination resistance for composite laminates effectively. In this paper, the effect of laminate thickness on the low velocity impact responses of Z-pinned laminates with [02/902]2S, [02/902]4S, and [02/902]6S layup patterns was explored. These laminates had nominal thickness of 2.1 mm, 4.5 mm and 6.9 mm, respectively. The impact energy was set to 5 J, 10 J, 20 J and 30 J, and the mechanical curves during the experiment were recorded. Afterwards, ultrasonic C-scanner, scanning electron microscope (SEM) and X-ray micro-computed tomography (μCT) were used to detect the impact-induced damage. The theoretical models for predicting the delamination initiation threshold and related threshold impact energy were consistent with the experimental data. The results showed that Z-pins had almost no effect on the delamination initiation, but Z-pinning became significant for delamination suppression as the impact energy exceeded the threshold impact energy. In addition, due to the improved penetration resistance, the maximum central displacements were suppressed with Z-pin implantation as the noticeable fiber breakage occurred. Due to the fact that the dominant failure mode changed from fiber breakage to delamination with the increase of the laminate thickness, the delamination damage and internal defect suppression for thin laminate was inferior to that for the intermediate-thickness laminate. However, the suppression effectiveness became weak for the thick laminate at the same impact energy due to the smaller bridging force with slight Z-pin pull-out.

Proprioceptive Stimulation Added to a Walking Self-Avatar Enhances the Illusory Perception of Walking in Static Participants

When immersed in virtual reality, users who view their body as a co-located virtual avatar that reflects their movements, generally develop a sense of embodiment whereby they perceive the virtual body to be their own. One aspect of the sense of embodiment is the feeling of agency over the avatar, i.e., the feeling that one is producing the movements of the avatar. In contexts such as physical rehabilitation, telepresence and gaming, it may be useful to induce a strong sense of agency in users who cannot produce movements or for whom it is not practical to do so. Being able to feel agency over a walking avatar without having to produce walking movements could be especially valuable. Muscle vibrations have been shown to produce the proprioceptive perception of movements, without any movement on the part of the user. The objectives of the current study were to: 1-determine if the addition of lower-limb muscle-vibrations with gait-like patterns to a walking avatar can increase the illusory perception of walking in healthy individuals who are standing still; 2-compare the effects of the complexity of the vibration patterns and of their synchronicity on the sense of agency and on the illusory perception of walking. Thirty participants viewed a walking avatar from a first-person perspective, either without muscle vibrations or with one of four different patterns of vibrations. These five conditions were presented pairwise in a two-alternative forced choice paradigm and individually presented, after which participants answered an embodiment questionnaire. The displacement of center of pressure of the participants was measured throughout the experiment. The results show that all patterns of proprioceptive stimulation increased the sense of agency to a similar degree. However, the condition in which the proprioceptive feedback was realistic and temporally aligned with the avatar’s leg movements led to significantly larger anteroposterior sway of the center of pressure. The frequency of this sway matched the cadence of the avatar’s gait. Thus, congruent and realistic proprioceptive stimulation increases the feeling of agency, the illusory perception of walking and the motor responses of the participants when viewing a walking avatar from a first-person perspective.

Weakened Connection between East China Summer Rainfall and the East Asia-Pacific Teleconnection Pattern

The interdecadal change in the relationship between the East Asia-Pacific (EAP) teleconnection pattern and rainfall over East China during boreal summer (June–August) was investigated using observation and reanalysis datasets during 1951–2018. As proposed in a previous study, summer rainfall in the Yangtze-Huaihe River (YH-R) valley is below (above) normal when a positive (negative) EAP event occurs. Based on the close relationship with the rainfall anomalies, the EAP teleconnection pattern has been widely used in the prediction of summer rainfall variations in the YH-R valley. However, we found that the rainfall anomalies in the YH-R basin associated with the EAP pattern were weaker and less evident after the late 1980s. This finding indicates a decreased relationship between the EAP pattern and YH-R basin summer rainfall after the late 1980s, and a decrease in the quality and skill of seasonal predictions of YH-R basin summer rainfall related to the EAP pattern. This pronounced weakening in the YH-R summer rainfall-EAP pattern connection is attributed to the northeastward displacement of the Japanese action center of the EAP pattern after the late 1980s, which caused weaker anomalous vertical motion and moisture transportation over the YH-R valley. The present research reveals that the interdecadal expansion in the size of the Indo-Pacific warm pool in the late 1980s is likely responsible for the northeastward shift in the Japanese action center of the EAP teleconnection pattern by modulating anomalous convective activities and the northward propagation of the EAP pattern.

Relationship between Respiratory Muscle Function and Postural Stability in Male Soccer Players: A Case-Control Study.

The important role of postural stability in exercise performance has been determined by several authors. Despite this, few studies have analyzed the relationship between respiratory muscles’ strength and postural stability in athletes. For this reason, the aim of this study was to investigate the relationship between postural stability and respiratory muscles’ function in male soccer players. A case-control study was conducted over twenty-eight healthy men (18 soccer players; 10 non-athletes). Inspiratory muscle strength (MIP) and respiratory resistance (MVV) were obtained through a digital spirometer. Stability variables were obtained in standing position on a stabilometric platform and in open and closed eyes conditions. The area and length of the center of pressures and displacements in the X and Y range were analyzed. Pearson’s coefficient was used to measure the linear correlation between MIP, MVV and stabilometric variables. In the soccer players’ group, MIP and MIP % predictive were inversely correlated with length (r = −0.535 and r = −0.585; p < 0.05) and X range (r = −0.527 and r = −0.560; p < 0.05), whereas MVV was directly correlated with length (r = 0.606; p < 0.01) and Y range (r = 0.558; p < 0.05). Our results show that the greater the inspiratory muscle strength, the less displacement of the pressure center, while at higher respiratory rates there is greater displacement.

Displacement of center of mass in dogs in response to foot sensory stimulation.

Evaluate center of mass (CoM) displacement values during four-limb and three-limb standing with limb suspension in dogs before and after applying sensory stimulation to a forelimb or hindlimb. Experimental study. Six clinically normal beagles. A four force-plate apparatus was built to assess static weight distribution. Dogs stood on the device with one limb in contact with each force plate. We created a plastic device to induce sensory stimulation so that lameness could not be detected visually when stimulating the paw. Experimenters confirmed the degree of lameness by walking before and after measurement. Body-weight shifts were induced via suspension of each limb and transient sensory stimulation to the right forelimb or left hindlimb. CoMs of five postures were compared, with and without transient sensory stimulation. The four-limb CoM was located cranial to the center of the X- and Y-axis coordinates (X: -0.82 ± 9.12, Y: 61.00 ± 5.82). During three-limb standing with suspension of either forelimb, CoM shifted backward toward the contralateral side compared to four-limb standing. During hindlimb suspension, CoM shifted to the contralateral side. With right forelimb sensory stimulation, there were large CoM changes for both four-limb and three-limb standing (X: -34.53 ± 9.09, Y: 52.21 ± 6.88). CoM changes were small with left hindlimb sensory stimulation (X: 6.47 ± 13.86, Y: 69.41 ± 5.55). CoMs during four-limb and three-limb standing were influenced by sensory stimulation of a forelimb and, to a lesser extent, of a hindlimb. Static evaluation of CoM may aid clinicians in the diagnosis and recovery of forelimb lameness.

Upward gaze direction increases center of pressure displacement and decreases squat stability

The purpose of this study was to quantify differences in barbell back squat stability as a function of gaze direction. Sixteen female subjects who were experienced in barbell back squatting performed six sets of three squat repetitions, randomized according to three gaze directions (DOWN, STRAIGHT, and UP). Stability was determined based on the displacement of center of pressure (COP) during each squat repetition, measured using a low-cost, portable force plate. Multiple t-tests with statistical significance set at p &lt; 0.05 were conducted between gaze directions and revealed significant differences in stability between the DOWN versus UP conditions. Specifically, DOWN had the smallest COP displacement, with significantly larger COP displacement in the UP condition (p = 0.02). There were no significant differences when DOWN or UP was compared to STRAIGHT (p = 0.22 and p = 0.28 respectively). From a practical standpoint, these results suggest that having a downward gaze direction during barbell back squat will maximize stability and reduce the likelihood of injury.

Influence of standoff distance on the deformation of square steel plates subjected to internal blast loadings

This study presents a combining experimental and numerical efforts on elucidating the influence of the standoff distance on large inelastic deformation of square steel plates subjected to the fully-confined internal blast loading from TNT detonation. Experimental results reveal that increasing standoff distance could lead to a monotonic increase of permanent central displacement of the target plate, which contradicts the well-known free-air blast scenarios. Detailed three-dimensional finite element simulations using LS-Dyna are carried out to provide additional insights into the pressure evolution and transient response of the ductile plates. The numerical results are validated against experimental data where they were found to be in reasonable agreements. Numerical predictions reveal that complex pressure wave interactions within the blast chamber, and the saturated impulse effect attribute, in part, or combination, to the aforesaid phenomenon. The discussions on the limitation of the current findings are also provided, highlighting its dependency on the confinement’s geometry.

Alterations in mechanical muscle characteristics and postural control induced by tennis match-play in young players.

BackgroundCentral and peripheric fatigue indicators are among the main reasons for performance decline following competition. Because of the impact of these factors on performance, how these variables are affected by match-play could be of interest, especially in young tennis players.ObjectiveThis study aimed to investigate alterations induced by a simulated tennis match on postural control and muscle characteristics in young tennis players.MethodSeventeen male junior players took part in pre- and post-competition testing sessions performing postural control (displacement, speed and surface area of center of pressures) and muscle characteristics measurements (tone, stiffness, time to relaxation and elasticity). Between trials, participants played an 80-min simulated tennis match.ResultsNo significant differences were observed in any of the tested variables. Moderate-to-large effect sizes (ES) for decreased stiffness and tone and greater time to relaxation were found between pre- and post-conditions in the right rectus abdominis (−9.8%, −4.4% and 7.8%; ES = 0.8, 0.54 and −0.85). Also, a decrease in tone was found in the right vastus medialis (−7.1%; ES = 0.56), while surface area of the center of pressures with eyes open showed trends towards increasing in post-match measurements (55.9%; ES = 0.56).ConclusionAn 80-min simulated tennis match seems insufficient to elicit significant changes in postural control and mechanical muscle characteristics. Results suggest that physiological responses triggered by match-play were closer to those seen after a moderate activity than those present following a strenuous task.

Penguin Suit and Fetal Position Finite Element Model to Prevent Low Back Pain in Spaceflight.

BACKGROUND: This study aimed to investigate the biomechanical effects of different interventions on astronauts lumbar intervertebral discs in a microgravity environment during spaceflight and in a gravity environment when the astronaut returns.METHODS: A finite element model of the L4L5 lumbar segment was developed with eight loading schemes representing different interventions. The loading schemes included no intervention, wearing a penguin suit, sleeping in a fetal position, wearing a penguin suit combined with sleeping in the fetal position, reclining for 4 or 16 h/d, and maintaining upright posture for 4 or 16 h/d.RESULTS: Without intervention, the microgravity environment led to increased central pore pressure, radial displacement, and water content in the lumbar intervertebral disc. Wearing a penguin suit combined with sleeping in the fetal position can reduce disc pore pressure, axial stress, radial displacement, and water content to 0.156 MPa, 11.50 kPa, 0.538 mm, and 1.390%, respectively. When astronauts return to the gravity environment, staying upright for 4 h can reduce the pore pressure, axial stress, radial displacement, and water content of the intervertebral disc to 0.222 MPa, 10.72 kPa, 0.373 mm, and 0.219%, respectively.CONCLUSION: This study showed that wearing a penguin suit and sleeping in the fetal position both have the potential to protect the lumbar intervertebral disc from the negative effects caused by microgravity. Remaining in the upright posture for 4 h per day may help squeeze out the water in the intervertebral disc safely when astronauts return to the gravity environment.Zhang S, Wang K, Zhu R, Jiang C, Niu W. Penguin suit and fetal position finite element model to prevent low back pain in spaceflight. Aerosp Med Hum Perform. 2021; 92(5):312318.

Effects of Attentional Focus on the Corticospinal Excitability during Anticipatory Postural Adjustments in Dart Throwing

Attentional focus can affect motor performance and learning. It is known that external focus (EF) which concentrated on the movement outcome leads better performance and efficient motor output rather than internal focus (IF) which concentrated on one's body movement. It remains unclear whether the attentional focus modulates the corticospinal excitability during anticipatory postural adjustments (APA). In the present study, we using transcranial magnetic stimulation (TMS) examined the excitability changes in the primary motor cortex (M1) during dart throwing with different attentional focuses. We hypothesized that the APA duration and magnitude is different between EF and IF conditions, and the corticospinal excitability of lower leg muscle increases in the phase of APA, while the extent to which modulation is different between conditions. Fifteen healthy volunteers were asked to perform dart throwing with the dominant hand with a visual cue under the EF condition (focus on the flight trajectory of the dart) and IF condition (focus on the elbow angle of the dominant hand). The participants performing the tasks stood on a force plate with the legs closed, and we measured the displacement of center of pressure (COP). Electromyography (EMG) was recorded from the anterior deltoid, triceps brachii (TB), tibialis anterior (TA), and soleus muscles. Because the EMG of TA muscle was clearly observed from about 300 ms before the EMG onset of TB muscle (agonist muscle of throwing), TMS was applied over the hotspot of TA muscle in the contralateral M1 at the timings of the visual cue, 0 to 100 ms prior to the EMG onset of TA muscle, and the EMG onset of TB muscle. The distance from the bulls-eye was significantly shorter with EF than that with IF. Neither the difference in the total length of COP and rectangle area nor in the APA duration and magnitude was observed between EF and IF conditions. The motor evoked potential (MEP) amplitude in the TA muscle at -100ms, -50 ms, TA onset, and TB onset significantly increased in comparison with that at control in both conditions. In particular, MEP at -50 ms, TA onset, and TB onset were significantly larger with EF than those with IF, whereas there were no significant differences in MEP at visual cue and -100 ms between EF and IF conditions. Our results demonstrate that the excitability of corticospinal projections to the lower leg muscle increases immediately prior to a ballistic movement of the upper limb. It suggests that, by changing the attentional focus the cortical contribution to the postural control is modulated which may improve motor performance and efficacy of the movement execution.

Functional and structural outcome after vitrectomy combined with subretinal rtPA Injection with or without additional intravitreal Bevacizumab injection for submacular hemorrhages.

BackgroundTo analyze the functional and anatomical outcome after vitrectomy with subretinal rtPA (recombinant tissue plasminogen activator) combined with or without an intravitreal Bevacizumab injection.Patients and methodsRetrospective, consecutive case series of 31 pseudophakic patients with submacular hemorrhage (SMH) due to neovascular age-related macular degeneration (AMD) treated with vitrectomy, subretinal rtPA and pneumatic air displacement with or without an additional intravitreal Bevacizumab injection. The primary endpoints were best-corrected visual acuity (BCVA), and central macular thickness (CMT) measured by SD‑OCT. The secondary endpoint was a displacement of hemorrhage from the subretinal space three months after surgery.Results31 eyes of 31 patients were treated with vitrectomy and subretinal rtPA. 17/31 were treated simultaneously with an intravitreal Bevacizumab injection (group +B) and 14/31 without (group -B). The mean visual acuity improved significantly in both groups (from 1.37±0.39 to 1.03±0.57 logMAR in +B and from 1.48±0.48 to 1.01±0.38 logMAR in group –B, p<0.05). The mean CMT decreased in group +B from 607±179 μm to 424±205 μm (p = 0.2) and in group –B from 722±216 μm to 460±202 μm (p<0.05). A central displacement of the hemorrhage could be achieved in 47% in group +B, whereas in group -B displacement could be achieved in 50% (p = 0.44).ConclusionsVitrectomy with subretinal rtPA injection and air tamponade with or without simultaneous intravitreal Bevacizumab injection displaces SMH and improves BCVA effectively. In comparison, the postoperative outcome is comparable regardless of whether or not intravitreal bevacizumab is applied simultaneously.

Comparison of gait recovery patterns according to the paralyzed side in stroke patients: An observational study based on a retrospective chart review (STROBE compliant).

Gait rehabilitations have been abundantly performed for post-stroke patients, because gait is the most important factor for the return of post-stroke patients to daily life. However, conventional uniform gait rehabilitations tend to be tedious and reduce motivation. The aim of this study was to contribute to the development of personalized rehabilitation of gait by identifying differences in gait recovery pattern according to the paralyzed side of post-stroke patients.The gait analysis was performed on stroke patients who are right-handed and can walk independently. We retrospectively analyzed the results of pelvic movements and displacement of center of pressure (COP) during gait using corresponding equipments. To show the difference of gait recovery pattern according to the paralyzed side, we divided subjects into two groups, right (n = 19) and left (n = 20) hemiparesis group. The measured variables were as follows: tilt, obliquity, and rotation symmetries of pelvis; area, velocity, and lateral symmetry of COP.First, in the left hemiparesis group, obliquity (P < .01) and rotation (P < .01) symmetries of the movement of the pelvis were significantly improved in the follow-up compared to the initial gait analysis. In the right hemiparesis group, tilt (P < .001), obliquity (P < .001), and rotation (P < .05) symmetries were significantly improved in the follow-up compared to the initial gait analysis. Second, COP area and COP velocity values in the follow-up were significantly smaller than those in the initial gait analysis in the left (P < .001, P < .05) and right (P < .001, P < .01) hemiparesis groups. The positive value of lateral symmetry increased, although not a significant difference statistically, as walking ability improved in both groups. In the correlation analysis among variables obtained using Treadmill, there were significant positive linear relationships between the lateral symmetry and the COP area (P < .05), and between the COP velocity and the lateral symmetry (P < .001) of the follow-up gait analysis in the right hemiparesis group.It was confirmed that the gait recovery pattern differs according to the paralyzed side of post-stroke patients and the role of the intact side, such as moving the COP to the intact side, is important for the improvement of gait function in both groups.This study was registered with the Clinical Research Information Service (CRIS) of the Korea National Institute of Health (NIH), Republic of Korea (KCT0002984) and was approved by the Institutional Review Board (IRB) of the WKUGH (WKIRB [2018-25], November 28, 2018).

Influence of a center of mass position on beam natural frequencies of vibration

The paper discusses the effect of beam center of mass displacements on the values of their first natural vibration frequencies. Three schemes of beam restraint with a displacement of the center of mass along all axes of a coordinate system and around them are considered. It is established that if the center of mass is in the center of the beam, then any of its small linear and angular displacements slightly affect the first natural frequencies of vibration. If the center of mass was near the support, its longitudinal displacements along the beam will significantly affect the first natural frequency of bending vibrations. The transverse displacements of the center of mass will change only the natural frequencies of the torsional vibrations of the beam, which are usually quite small. Small angular displacements of the beam center of mass do not change the first natural frequencies of vibration at any location relative to the beam.

Stress Wave Mitigation Properties of Dual-meta Panels against Blast Loads

A dual-meta panel functioning as a sacrificial cladding is proposed and its blast mitigation capacity is investigated in this study. The proposed panel possesses the potential to generate bandgaps that target at a specific range of frequencies to stop stress wave propagating through the panel, leading to the favourable stress wave mitigation for structural protection. Aside from the unique stress wave manipulation capability, more energy can be absorbed by a combination of plastic deformation and local resonance. The effectiveness of the proposed panel is validated through numerical simulations. An analytical solution of wave propagation in an ideal meta truss bar is derived to validate the numerical model with good agreement. It is found that the proposed dual-meta panel exhibits an increase in energy absorption, a reduction in transmitted reaction force (up to 30%), and the back plate central displacements (up to 20%) compared to other conventional sandwich panels, e.g. sandwich panel with hollow trusses and solid trusses, in resisting blast loadings. In pursuit of optimizing the performance of the proposed panel, parametric investigations are also conducted to examine the influences of the plate thickness, boundary condition, and the blast load profiles including duration and intensity on the transient response of the proposed dual-meta panel.

MORPHOMETRIC PARAMETERS AND FEATURES OF THE TOPOGRAPHY OF HUMAN PERINEAL BODY

In modern specialized literature, there is practically no information about the shape, size and topography of one of the most important formations of the perineum - of the perineal body. Knowledge of the anatomical aspects of the structure and location of the perineal center would allow in the future to reduce the postoperative complications associated with unintentional damage. The question of the morphology of the perineal body and associated muscles in clinical practice in obstetric traumatism remains relevant. The aim of the study was to study the morphometric parameters and features of the topography of the human perineal body. The objects of the study were 50 autopsy cases of people aged 60-87 years, 25 of each sex, who died from causes not related to the pathology of the pelvic organs. In each case, the perineal body, location of its center and associated muscles were identified. Methods of classical anatomical preparation, description and statistical analysis were used in the work. As a result of the work, five forms of the perineal body were identified: cruciform, «hourglass», triangular, round, polygonal. There were also cases where it was not possible to determine the shape of the intersection of the fibers. For men, the most common triangular shape, for women - the shape of an «hourglass». In most cases in which the shape of the intersection of the fibers was determined, there were clearly identifiable tendon fibers, that is, the tendinal center of the perineal body was present. The average area of ​​the tendinal center of the perineal body in women was 0.99±0.47 cm², and in men 0.94±0.32 cm². The ratio of cases of displacement of the tendinal center towards the right or left ischial tuberosities is almost equal to 10 cases towards the right ischial tuberosity and 11 cases towards the left. When evaluating the pubo-coccygeal asymmetry, in most cases with a triangular shape, there is a sharp displacement towards the apex of the coccyx. Also, the authors found that the average area of ​​the tendinal center of the perineal body is larger in women than in men. Thus, the human perineal body has a variety of forms, according to the authors, associated not only with the embryological features of the development of the muscles of the perineum, but also with the lifestyle, a history of diseases and surgical interventions in the area of ​​the tendinal center of the perineal body.

The effect of eight-week elastic walking exercise on the pattern of plantar pressure distribution in women with chronic low back pain during walking

Background: Training of elastic walking is a new method for elasticity in gait and correction of the distribution pattern of plantar pressure in patients with low back pain during gait. This study aimed to investigate the distribution pattern of plantar pressure during gait in women with low back pain following 8 weeks-training of elastic walking. Methods: The present study was quasi-experimental. In this research, 20 women with low back pain were divided into control (n=11) and experimental (n=9) groups. Subjects from the experimental group performed elastic gait training for 3 sessions per week for 8 weeks while the control group didn’t have any exercise program. The plantar pressure variables included the peak of vertical ground reaction forces, the time to peak of ground reaction forces, loading rate, the peak of plantar pressure on the ten foot regions, the peak of ground reaction forces on the ten foot regions, and displacement of the pressure center in two internal-external (copx) and anterior-posterior (copy) lines. The distribution pattern of plantar pressure during gait was recorded by a foot scan system (Sampling rate 300 Hz) in pre-training and post-training. Two-way ANOVA was used to analyze the data. The significance level was set at P &lt; 0.05. Results: In the experimental group, the results of this study demonstrated lower peak vertical reaction force (FzMS component) during post-test compared with pre-test (P = 0.002). Moreover, findings showed that the main effect of group on peak pressure in the mid-foot region was significant (P = 0.011). The results showed no significant difference concerning the main effect of group, the main effect of time and effect, interaction time and group on peak vertical reaction force, displacement of pressure center, vertical loading rate, and walking stance time (P &gt; 0.05). Conclusion: The findings of this study showed that training of elastic walking does not have a significant effect on stance time. Also, training of elastic walking in the experimental group reduced the peak vertical ground reaction force (FzMS component) during the post-test compared with the pre-test that can correct the walking pattern and improve the chronic low back pain.

Organization of radial glia reveals growth pattern in the telencephalon of a percomorph fish Astatotilapia burtoni.

In the brain of teleost fish, radial glial cells are the main astroglial cell type. To understand how radial glia structures are adapting to continuous growth of the brain, we studied the astroglial cells in the telencephalon of the cichlid fish Astatotilapia burtoni in small fry to large specimens. These animals grow to a standard length of 10-12 cm in this fish species, corresponding to a more than 100-fold increase in brain volume. Focusing on the telencephalon where glial cells are arranged radially in the everted (dorsal) pallium, immunocytochemistry for glial markers revealed an aberrant pattern of radial glial fibers in the central division of the dorsal pallium (DC, i.e., DC4 and DC5). The main glial processes curved around these nuclei, especially in the posterior part of the telencephalon. This was verified in tissue-cleared brains stained for glial markers. We further analyzed the growth of radial glia by immunocytochemically applied stem cell (proliferating cell nuclear antigen [PCNA], Sox2) and differentiation marker (doublecortin) and found that these markers were expressed at the ventricular surface consistent with a stacking growth pattern. In addition, we detected doublecortin and Sox2 positive cells in deeper nuclei of DC areas. Our data suggest that radial glial cells give rise to migrating cells providing new neurons and glia to deeper pallial regions. This results in expansion of the central pallial areas and displacement of existing radial glial. In summary, we show that radial glial cells can adapt to morphological growth processes in the adult fish brain and contribute to this growth.

Finite element analysis on the residual bearing capacity of axially preloaded tubular T-joints subjected to impacts

Understanding the dynamic behavior of tubular members is necessary for ensuring their safety, even when damaged after an impact. A nonlinear finite element analysis (FEA) was performed to evaluate the residual bearing capacity of axially preloaded square hollow section (SHS) T-joints subjected to impact loading. First, the Bao–Wierzbicki fracture criterion was used to simulate the failure modes and behavior of specimens subjected to static axial compression and impacts, and the numerical results were compared with experimental results in the literature. The bearing capacity error between the numerical and experimental results was within 10%, which verified the accuracy of the finite element (FE) model. Then, the local and global displacements of joints were distinguished with the central line displacement method, and 40 FE models were created. The dynamic responses of joints under impact loading were used to study the resistance mechanism. Joint deformation mainly manifested as outward buckling of the chord webs and indentation of the chord upper flange. The in-plane restraint and support by the brace of the chord increased with the brace–chord width ratio. Finally, the ultimate residual bearing capacity coefficient ψ was defined as the ratio of the ultimate bearing capacities of the impacted and reference specimen, and the influence of different parameters, including axial preloading, impact energy, brace–chord width ratio, and chord diameter, was explored. Axial preloading and impact energy showed a negative correlation with ψ, while the brace–chord width ratio and chord diameter showed a significant positive correlation with ψ.

Large deformation behavior of functionally graded porous curved beams in thermal environment

The in-plane thermoelastic response of curved beams made of porous materials with different types of functionally graded (FG) porosity is studied in this research contribution. Nonlinear governing equations are derived based on the first-order shear deformation theory along with the nonlinear Green strains. The nonlinear governing equations are solved by the aid of the Rayleigh–Ritz method along with the Newton–Raphson method. The modified rule-of-mixture is employed to derive the material properties of imperfect FG porous curved beams. Comprehensive parametric studies are conducted to explore the effects of volume fraction and various dispersion patterns of porosities, temperature field, and arch geometry as well as boundary conditions on the nonlinear equilibrium path and stability behavior of the FG porous curved beams. Results reveal that dispersion and volume fraction of porosities have a significant effect on the thermal stability path, maximum stress, and bending moment at the crown of the curved beams. Moreover, the influence of porosity dispersion and structural geometry on the central radial and in-plane displacement of the curved beams is evaluated. Results show that various boundary conditions make a considerable difference in the central radial displacements of the curved beams with the same porosity dispersion. Due to the absence of similar results in the specialized literature, this paper is likely to provide pertinent results that are instrumental toward a reliable design of FG porous curved beams in thermal environment.