In this study, we explore the solar differential rotation using recurrent sunspots observed by space-borne instruments from August 1996 to June 2025. To avoid systematic errors, the differential rotation profiles are calculated taking into account both Earth’s elliptical orbit and the inclination of the solar rotation axis to the ecliptic. We have found that the equatorial rotation rate first increases and then decreases in Solar Cycles 23, 24, and 25, which can be interpreted as torsional oscillations with a period of approximately 11 years. When comparing the angular rotation rates at the solar maximum and minimum, the latitudinal gradient of rotations at solar minima exhibits significant cycle-to-cycle variation. During the descending phase, the latitudinal gradient of rotations changes significantly between solar cycles. The latitudinal gradient of rotations in the northern hemisphere is comparable across solar cycles, whereas that in the southern hemisphere displays significant modulations across solar cycles. In terms of the Zürich sunspot classification system, the equatorial rotation rate is higher and the differential rotation is stronger for J-type groups than for H-type groups. It is also attempted to investigate the dependence on the order of successive passages, revealing that although the equatorial rotation rates for the first and second passages are similar, the differential rotation for the second passage appears significant. This is indicative of less rigid rotation during the second passage. To conclude, we point out that the Sun appears to rotate more differentially in the case that the solar magnetic activity is relatively weaker, when comparing cases of weak and strong solar activity.

Background: Pressure biofeedback may facilitate selective rotator cuff activation during shoulder external rotation, but training effects and structural changes are unclear. Objectives: To examine the effects of a 4-week external rotation program with pressure biofeedback on shoulder muscle activity and rotator cuff thickness. Design: Quasi-experimental design. Methods: Thirty healthy adults were randomized to experimental (n=15) or control (n=15). Both performed seated external rotation at 30° with an elastic band (3×12 reps, 4 sessions/week, 4-week); the biofeedback group maintained 40 mmHg scapular adduction pressure. Surface EMG (%MVIC) and ultrasound muscle thickness were assessed pre/post. Paired and independent t-tests were used (α=.05). Results: In the experimental group, teres minor and infraspinatus activity increased, whereas middle and posterior deltoid activity decreased (P<.05). Post-intervention, rotator cuff activity was higher and posterior deltoid activity was lower versus control (P<.05). Muscle thickness showed no significant changes. Conclusions: A 4-week pressure biofeedback training program changed muscle activation during shoulder external rotation by increasing rotator cuff activation and decreasing compensatory deltoid activity. These findings indicate meaningful neuromuscular adaptations during the external rotation task.

Background: Tensor fasciae latae (TFL) and iliotibial tract (ITB) tightness can pull the pelvis during hip lateral rotation (HLR), increasing pelvic rotation due to muscle tension. Among various tests, the HLR test in the prone position (HLRP) is a clinical evaluation tool for assessing lumbopelvic motion with lower-extremity movement. However, performing the HLRP may result in less compensatory motion and a relatively decreased pelvic rotation angle (PRA) because of a wide base of support. Moreover, there were no studies investigating PRA during an HLR test in the standing position (HLRS). Objects: This study aimed to compare the PRA in the horizontal plane during HLRS and the HLRP between individuals with and without TFL/ITB tightness. Methods: Thirty participants with (n = 15) and without (n = 15) TFL/ITB tightness as assessed by Ober’s test, were recruited. The PRA was measured during active HLRS and HLRP. Two-way mixed analysis of variance was used to identify significant differences in the PRA between groups and within positions. Results: When HLRP and HLRS were performed, the PRA in the horizontal plane occurred at 1.65° ± 0.98° and 7.68° ± 4.69°, respectively, in the TFL/ITB tightness group, and at 1.27° ± 1.07° and 2.37° ± 1.96°, respectively, in the control group. A significant interaction effect was identified between groups and positions on the PRA (p < 0.05). Individuals with TFL/ITB tightness had a significantly greater PRA during HLRS than those in the control group. The PRA during HLRS was significantly greater than that during HLRP in individuals with TFL/ITB tightness. Conclusion: These results suggest that TFL/ITB tightness contributes to increased PRA during HLRS compared with HLRP. Clinically, assessment of the PRA in the standing may provide a functional indicator of compensatory pelvic motion during hip rotation of 45°.

Background: Cross-legged sitting posture (CLSP) is common in daily life but may cause asymmetrical loading of the pelvis and spine, potentially leading to postural imbalance and musculoskeletal problems. Although short-term effects of CLSP have been reported, the longterm biomechanical consequences of habitual CLSP remain unclear. Objects: This study compared lumbopelvic alignment and rotational asymmetry between individuals with and without habitual CLSP. Methods: Thirty healthy adults were classified into CLSP (n = 15) and non-CLSP (NCLSP; n = 15) groups based on self-reported sitting habits. Transverse plane pelvic rotation angle (TrPRA) in the supine position and during active straight leg raise (ASLR) was measured using a Smart KEMA motion sensor system, and side-lying lumbopelvic rotation range of motion (SLRR) was assessed with a custom device. Asymmetry index (AI) was calculated for left–right differences. Group comparisons were analyzed using independent t-tests (p < 0.05). Results: Intra-rater reliability of SLRR was very high (intraclass correlation coefficient = 0.958–0.986). No significant group differences were found in TrPRA in the supine position (p > 0.05) or AI of TrPRA during ASLR (p > 0.05). However, the CLSP group demonstrated significantly greater AI in SLRR than the NCLSP group (13.21% ± 6.64% vs. 7.06% ± 4.90%, p = 0.008, Cohen’s d = 1.05). In 10 of the 15 CLSP subjects, the direction of lumbopelvic rotation corresponded to the preferred leg-crossing side. Conclusion: Habitual unilateral CLSP is associated with significantly greater lumbopelvic rotational asymmetry during active side-lying movement, which may contribute to functional imbalance and increased injury risk. Preventive and corrective strategies should include limiting prolonged CLSP, adopting ergonomic seating, and implementing bilateral mobility, rotational control, and core stability exercises. Postural retraining with visual feedback and task-specific practice may further promote symmetrical sitting habits in clinical and occupational environments.

Background: Neck discomfort and movement limitations are common musculoskeletal problems among modern people. While cervical and thoracic joint mobilization are widely used interventions for cervical dysfunction, research comparing their immediate effectiveness in adults with asymmetrical cervical rotation is limited. Objectives: To compare the immediate effects of cervical versus thoracic joint mobilization in adults with adults with asymmetrical cervical rotation and discomfort. Design: Randomized controlled trial. Methods: Thirty adults with left-right differences in cervical rotation of more than 5 degrees were randomly assigned to a cervical mobilization group (CMG, n=15) or thoracic mobilization group (TMG, n=15). Both groups received Grade III mobilization for 15 minutes. Range of motion (ROM), pain (VAS), and neck disability index (NDI) were measured before and after intervention. Results: Both groups showed significant increases in ROM after intervention (P<.001). Within-group analysis revealed that the TMG showed significant pain reduction (P<.01) and significant reduction in left-right rotation asymmetry (P<.001), while the CMG showed improvement in ROM but no significant changes in asymmetry or pain (P>.05). Neither group showed significant changes in NDI. Between-group comparisons showed no significant differences in any outcome measures. Conclusion: Both cervical and thoracic joint mobilization increased cervical range of motion in adults with asymmetrical cervical rotation discomfort. The TMG demonstrated significant within-group improvements in left-right rotation asymmetry and pain reduction, suggesting potential clinical benefits of thoracic mobilization for certain aspects of cervical dysfunction.

In this paper, the design feasibility of the high-temperature rotation test jig for the operating state of gas turbine blades was confirmed through thermal structural analysis and modal analysis. The structural analysis model was composed of assembled blade, disc, cover, and shaft. Here, the disc was designed to be assembled with two types of blade. First, thermal analysis was performed by applying the blade surface temperature of 800°C. Next, structural analysis was performed at 3600 RPM, the normal operating condition, and 4320 RPM, the overspeed operation condition. Lastly, modal analysis was performed to examine the natural frequency and deformation of the jig. The FE analysis showed that the temperature decreased from the blade to disc dovetail. Additionally, both the blade and disc showed structural stability as the maximum stress was below the yield strength. Also, the first natural frequency was 636.35Hz and 639.43Hz at 3600RPM and 4320RPM, respectively, satisfying gas turbine design standards and guidelines. Ultimately, the designed test jig was confirmed to be capable of high temperature and rotation testing of various blades.

This study was conducted in the San Pedro Department to determine the impact of different soil management practices on sesame productivity. Different tillage methods (conventional deep tillage, minimum tillage, and no-tillage), crop rotations (monoculture, double, and triple rotation), various combinations of green manure, and appropriate doses of chemical fertilizers were studied. The results revealed that the no-tillage method combined with crop rotation (corn-cotton-sesame) and fertilization had the highest productivity of 1,548 kg/ha. In contrast, the conventional deep tillage method without fertilization showed the lowest productivity with 614 kg/ha. Incorporation of summer green manures (Mucuna pruriens) in minimum tillage methods with fertilization significantly improved productivity (1,010 kg/ha) in comparison with the same tillage method and fertilization but without Mucuna (720 kg/ha), which highlights the synergistic effects of combining green manures with chemical fertilizers. The treatment of winter green manures consisting of black oat + white lupine and black oat + radish has also significantly improved the productivity of sesame with 904 and 900 kg/ha, respectively, compared to the non-use of winter green manure and the use of chia, which had productivities of 695 and 298 kg/ha, respectively. The best chemical fertilization doses of nitrogen (urea 45% N), phosphorus (46% P2O5), and potassium (60% K2O) were determined through tests with increasing doses of each nutrient, maintaining 40 kg/ha as the base for the other two. The highest productivity was obtained with N, P, and K levels of 70 kg/ha each, resulting in productivities of 1,421, 1,522, and 1,486 kg/ha. However, the maximum profit compared to the input is obtained with doses of 50 kg/ha for N and 60 kg/ha for P and K, giving a productivity of 1,390, 1,510, and 1,421 kg/ha, respectively.

Background: The abdominal drawing-in maneuver (ADIM), a method of lumbar stabilization training, is an effective neuromuscular intervention for lumbar instability associated with low back pain (LBP). Objects: The purpose of this study was to compare the effect of a 2-week period of the ADIM and tensor fasciae latae-iliotibial band (TFL-ITB) self-stretching on lumbopelvic rotation angle, lumbopelvic rotation movement onset, TFL-ITB length, and pain intensity during active prone hip lateral rotation. Methods: Twenty-two subjects with lumbar extension rotation syndrome accompanying shortened TFL-ITB (16 males and 6 females) were recruited for this study. The subjects were instructed how to perform ADIM training or ADIM training plus TFL-ITB self-stretching program at home for a 2-week period. A 3-dimensional ultrasonic motion analysis system was used to measure the lumbopelvic rotation angle and lumbopelvic rotation movement onset. An independent t-test was used to determine between-group differences for each outcome measure (lumbopelvic rotation angle, lumbopelvic rotation movement onset, TFL-ITB length, and pain intensity). Results: The results showed that ADIM training plus TFL-ITB self-stretching decreased the lumbopelvic rotation angle, delayed the lumbopelvic rotation movement onset, and elongated the TFL-ITB significantly more than did ADIM training alone. Pain intensity was lower in the ADIM training plus TFL-ITB self-stretching group than the ADIM training alone group; however, the difference was not significant. Conclusion: ADIM training plus TFL-ITB self-stretching performed for a 2-week period at home may be an effective treatment for modifying lumbopelvic motion and reducing LBP.

Background: Limitations of shoulder range of motion (ROM), particularly shoulder internal rotation (SIR), are commonly associated with musculoskeletal disorders in both the general population and athletes. The limitation can result in connective tissue lesions such as superior labrum tears and symptoms such as rotator cuff tears and shoulder impingement syndrome. Maintaining the center of rotation of the glenohumeral joint during SIR can be challenging due to the compensatory scapulothoracic movement and anterior displacement of the humeral head. Therefore, observing the path of the instantaneous center of rotation (PICR) using the olecranon as a marker during SIR may provide valuable insights into understanding the dynamics of the shoulder joint. Objects: The aim of the study was to compare the displacement of the olecranon to measure the rotation control of the humeral head during SIR in individuals with and without restricted SIR ROM. Methods: Twenty-four participants with and without restricted SIR ROM participated in this study. The displacement of olecranon was measured during the shoulder internal rotation control test (SIRCT) using a Kinovea (ver. 0.8.15, Kinovea), the 2-dimensional marker tracking analysis system. An independent t-test was used to compare the horizontal and vertical displacement of the olecranon marker between individuals with and without restricted SIR ROM. The statistical significance was set at p < 0.05. Results: Vertical displacement of the olecranon was significantly greater in the restricted SIR group than in the control group (p < 0.05). However, no significant difference was observed in the horizontal displacement of the olecranon (p > 0.05). Conclusion: The findings of this study indicated that individuals with restricted SIR ROM had significantly greater vertical displacement of the olecranon. The results suggest that the limitation of SIR ROM may lead to difficulty in rotation control of the humeral head.

Prepreg is an abbreviation of Preimpregnated Materials. It is a sheet-type product in which a matrix is ​​impregnated with reinforced fiber. The prepreg has very different properties depending on the orientation of the fibers and the weaving method, and the orientation of the fibers plays an important role in determining the mechanical strength of CFRP. Short and randomly oriented reinforcing fibers show isotropy, while long, unidirectional reinforcing fibers exhibit anisotropic behavior and are strongest when the applied load is parallel to the reinforcing fibers. Classification by the direction of the fiber is divided into unidirectional, orthogonal, multiaxial, and the like. Uni-directional refers to a state in which almost all fibers in the fabric are aligned in one direction. When the fibers used as reinforcing materials are aligned in one direction, the fibers are used in a straight line without twisting during the fabric production process, and there is an advantage in that the amount of fibers used as a whole can be minimized. A uni-directional prepreg exhibits different cutting forces depending on the stacking orientation angle. In this experiment, the optimal cutting conditions for a uni-directional prepreg 45 degree orientation angle specimen are presented.

Background: The external rotation (ER) exercise in performed at a 90° abduction of the shoulder joint is an effective to strengthen the infraspinatus. However, failure of the humeral head to control axial rotation during exercise can be increased the posterior deltoid over activity. Biofeedback training is an effective method of promoting motor learning and control it could look forward to activate the infraspinatus selectively by controlling the humeral head during exercise. Objects: The aim of this study was investigated that whether biofeedback for axial rotation was effective to activate selectively the infraspinatus during ER exercise. Methods: The 15 healthy males participated, and all subjects performed both ER exercise in a sitting position with shoulder abducted 90° under conditions with and without axial rotation biofeedback. Exercise was performed in a range of 90° ER, divided into three phases: concentric, isometric, and eccentric. The infraspinatus and posterior deltoid muscle activity were observed using surface electromyography. Results: Both infraspinatus activity (p < 0.01) and infraspinatus to posterior deltoid activity ratio (p = 0.01) were significantly higher with biofeedback however, posterior deltoid activity was significantly lower with biofeedback (p = 0.01). The infraspinatus muscle activity and muscle activity ratio were the highest in the isometric contraction type, and there were significant differences for all contraction types (p < 0.05). Whereas, the posterior deltoid activity was the lowest in the isometric contraction type, and showed a significant difference between isometric and other two contraction types (p < 0.05), but no significant different between concentric and eccentric contraction. Conclusion: Our results indicate that the axial rotation biofeedback during sitting ER exercise might be effective method to activating selective infraspinatus muscle and recommended to enhance the dynamic stability of the shoulder joint.

Background: The gluteus maximus (GM) muscle comprise the lumbo-pelvic complex and is an important stabilizing muscle during leg extension. In patients with low back pain (LBP) with weakness of the GM, spine leads to compensatory muscle activities such as instantaneous increase of the erector spinae (ES) muscle activity. Four-point kneeling arm and leg lift (FKALL) is most common types of lumbopelvic and GM muscles strengthening exercise. We assumed that altered hip position during FKALL may increase thoraco-lumbar stabilizer like GM activity more effectively method. Objects: The purpose of this study was investigated that effects of the three exercise postures on the right-sided GM, internal oblique (IO), external oblique (EO), and multifidus (MF) muscle activities and pelvic kinematic during FKALL. Methods: Twenty eight healthy individuals participated in this study. The exercises were performed three conditions of FKALL (pure FKALL, FKALL with 120° hip flexion of the supporting leg, FKALL with 30° hip abduction of the lifted leg). Participants performed FKALL exercises three times each condition, and motion sensor used to measure pelvic tilt and rotation angle. Results: This study demonstrated that no significant change in pelvic angle during hip movement in the FKALL (p > 0.05). However, the MF and GM muscle activities in FKALL with hip flexion and hip abduction is greater than pure FKALL position (p < 0.001). Conclusion: Our finding suggests that change the posture of the hip joint to facilitate GM muscle activation during trunk stabilization exercises such as the FKALL.