Ions trapped by electron beams in the rings oscillate with a certain frequency in the beam potential. The oscillation, which is incoherent at the early stage, becomes coherent and shakes the beam with a frequency. This is the mechanism of the ion instability. We investigate the fast-ion instability in the two proposed International Linear Collider damping rings of OCS6 and FODO4 with a high intensity and a lowemittance in which the growth rate may be very rapid. We have performed a simulation based on the weak-strong model and analytical estimate to investigate characteristic phenomena of the fast-ion instability that is a critical issue in the damping rings. We investigated the effects of the ion frequencies, bunch filling patterns, vacuum pressures, and a feedback system on the fast-ion instabilities in the damping rings. The interactions between ions and beams in our simulations were performed using the magnetic components of the damping ring. The simulation results show that the bunch-by-bunch feedback of about 50 turns is sufficient to suppress the fast-ion instabilities in the damping ring. It is estimated that the tune shifts in the beam due to the ions are small.
Summary
We aimed to investigate the association between cadmium levels and the risk of osteopenia and osteoporosis in Korean post-menopausal women. There was a significant positive association between cadmium levels and the risk of osteopenia and osteoporosis, but further studies for dose response are required.
Purpose
Cadmium exposure can exert detrimental effects on bone health, particularly in post-menopausal women. However, previous studies have failed to report an association in Korean post-menopausal women. We aimed to investigate the association between cadmium levels and the risk of osteopenia and osteoporosis in Korean post-menopausal women.
Methods
In total, 5432 participants from the 4th and 5th Korean National Health and Nutrition Examination Survey (KNHANES) were randomly sampled for measurements of heavy metal concentrations in the blood, bone mass density (BMD), and nutrient intake. We analyzed data for 1031 post-menopausal women ≥50 years of age. Blood cadmium levels were categorized into quartiles, and a multinomial logistic regression model was used for analysis.
Results
There was a significant positive association between cadmium levels and the risk of osteopenia and osteoporosis, but the odds ratio (OR) at the 4th level was lower than that at the 3rd level (OR and 95% confidence interval (CI) for osteopenia: 2nd quartile: 1.24, 0.88-1.74; 3rd quartile: 3.22, 2.24-4.64; 4th quartile: 1.27, 0.87-1.85; P for trend <0.001; OR and 95% CI for osteoporosis: 2nd quartile: 1.54, 1.05-2.25; 3rd quartile: 3.63, 2.31-5.69; 4th quartile: 1.70, 1.03-2.81; P for trend <0.001). This trend was consistent in the sensitivity analysis.
Conclusion
Our findings suggest that there is an association between blood cadmium levels and the risk of osteopenia and osteoporosis in Korean post-menopausal women. However, further prospective studies are required to determine whether there is a dose-response relationship and address potential selection bias, especially in patients with femoral neck osteoporosis.
Objective To determine whether pain is associated with gait instability in patients with lumbar disc herniation (LDH). Methods This retrospective cross-sectional study used data from electronic medical records. Among patients with lumbar back pain caused by LDH between January 2017 and July 2019, patients that underwent gait analysis were included. LDH was diagnosed using magnetic resonance imaging. An OptoGait photoelectric cell system was used for gait evaluation. Instability was measured using a gait symmetry index. Multivariate linear regression analysis was performed to determine the association between lumbar pain and gait instability. Results A total of 29 patients (12 females [41.4%] and 17 males [58.6%]; mean ± SD age, 40.6 ± 12.0 years) with LDH were enrolled in the study. With each 1-point increase in lumbar pain on the numeric rating scale, the symmetry index of the stance phase (0.33; 95% confidence interval [CI] 0.04, 0.62), swing phase (0.78; 95% CI 0.14, 1.43) and single support (0.79; 95% CI 0.15, 1.43) increased. Conclusions Gait instability in patients with LDH may occur due to an increase in pain.
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