Dynamic Compensation Temperature in the Mixed Spin-½ and Spin-⅔ Ising Model in an Oscillating Field on Alternate Layers of Hexagonal Lattice

Bayram Deviren,Mustafa Keskin,Osman Canko 한국자기학회 2008 한국자기학회 학술연구발표회 논문개요집 Vol.- No.-

Magnetic Properties of a Mixed Spin-3/2 and Spin-2 Ising Ferrimagnetic System within the Effective-field Theory

Bayram Deviren,Ersin Kantar,Mustafa Keskin 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.6

The magnetic properties of the ferrimagnetic mixed spin-3/2 and spin-2 Ising model with a crystal field in a longitudinal magnetic field on a honeycomb ( = 3) and a square lattice ( = 4) are studied by using the effective-field theory with correlations. The ground-state phase diagram of the model is obtained in a longitudinal magnetic field (h) for a single-ion potential or a crystal-field interaction () plane. We also investigate the thermal variations of the sublattice magnetization, and present the phase diagrams in the (/|J|, kBT/|J|) plane. The susceptibility, internal energy, and specific heat of the system are numerically examined, and some interesting phenomena in these quantities are found due to the applied longitudinal magnetic field. Moreover, the system undergoes first- and second-order phase transitions; hence, the system has a tricritical point. The system also exhibits reentrant behaviors.

Contribution of Lateral Interbody Fusion in Staged Correction of Adult Degenerative Scoliosis

Choi, Seung Won,Ames, Christopher,Berven, Sigurd,Chou, Dean,Tay, Bobby,Deviren, Vedat The Korean Neurosurgical Society 2018 Journal of Korean neurosurgical society Vol.61 No.6

Objective : Lateral interbody fusion (LIF) is attractive as a less invasive technique to address anterior spinal pathology in the treatment of adult spinal deformity. Its own uses and benefits in treatment of adult degenerative scoliosis are undefined. To investigate the radiographic and clinical outcomes of LIF, and staged LIF and posterior spinal fusion (PSF) for the treatment of adult degenerative scoliosis patients, we analyzed radiographic and clinical outcomes of adult degenerative scoliosis patients who underwent LIF and posterior spinal fusion. Methods : Forty consecutive adult degenerative scoliosis patients who underwent LIF followed by staged PSF at a single institution were retrospectively reviewed. Long-standing 36" anterior-posterior and lateral radiographs were taken preoperatively, at inter-stage, 3 months, 1 year, and 2 years after surgery were reviewed. Outcomes were assessed through the visual analogue scale (VAS), 36-Item Short Form Health Survey (SF-36), and Oswestry Disability Index (ODI). Results : Forty patients with a mean age of 66.3 (range, 49-79) met inclusion criteria. A mean of 3.8 levels (range, 2-5) were fused using LIF, while a mean of 9.0 levels (range, 3-16) were fused during the posterior approach. The mean time between stages was 1.4 days (range, 1-6). The mean follow-up was 19.6 months. Lumbar lordosis was significantly restored from $36.4^{\circ}$ preoperatively up to $48.9^{\circ}$ (71.4% of total correction) after LIF and $53.9^{\circ}$ after PSF. Lumbar coronal Cobb was prominently improved from $38.6^{\circ}$ preoperatively to $24.1^{\circ}$ (55.8% of total correction) after LIF, $12.6^{\circ}$ after PSF respectively. The mean pelvic incidence-lumbar lordosis mismatch was markedly improved from $22.2^{\circ}$ preoperatively to $8.1^{\circ}$ (86.5% of total correction) after LIF, $5.9^{\circ}$ after PSF. Correction of coronal imbalance and sagittal vertebral axis did not reach significance. The rate of perioperative complication was 37.5%. Five patients underwent revision surgery due to wound infection. No major perioperative medical complications occurred. At last follow-up, there were significant improvements in VAS, SF-36 Physical Component Summary and ODI scores. Conclusion : LIF provides significant corrections in the coronal and sagittal plane in the patients with adult degenerative scoliosis. However, LIF combined with staged PSF provides more excellent radiographic and clinical outcomes, with reduced perioperative risk in the treatment of adult degenerative scoliosis.

Correlation of Paraspinal Muscle Mass With Decompensation of Sagittal Adult Spinal Deformity After Setting of Fatigue Post 10-Minute Walk

배준석,Ashwin Sathe,이세민,Alexander A. Theologis,Vedat Deviren,이상호 대한척추신경외과학회 2021 Neurospine Vol.18 No.3

Objective: The purpose of this study was to investigate the changes in spinopelvic parameters before and after the setting of muscle fatigue along with its correlation with pre-existing paraspinal and psoas muscle mass. Methods: Single-center retrospective review of prospectively collected data was conducted on 145-adults with symptomatic loss of lumbar lordosis (LL). Radiographs were taken before and after walking for 10 minutes. Magnetic resonance imaging was used to calculate paraspinal muscle (PSM) cross-sectional area (CSA), mean signal intensity, fatty infiltration (FI), and lean muscle mass at thoracolumbar junction (T12) and lower lumbar level (L4). Psoas CSA was calculated at L3. Patients were divided into 2 groups namely compensated sagittal deformity (CSD) (SVA ≤4 cm, PT>20°) and decompensated sagittal deformity (DSD) (SVA>4 cm, PT>20°) based on prewalk measurements. Results: Initial mean SVA was 1.8 cm and 11 cm for CSD and DSD respectively (p<0.01). After walking, significant deteriorations in SVA, PT–LL (p<0.01) were observed in CSD without significant change in thoracic kyphosis (TK). All sagittal parameters in DSD deteriorated significantly. DSD group had significantly poorer PSM quality at T12 and L4 compared to CSD group. In CSD group, sagittal decompensation correlated with muscle quality, i.e., decreases in LL (ΔLL) correlated with CSA of PSM/vertebral body (VB) at L4 (r= -0.412, p=0.046) while increases in TK (ΔTK) correlated with CSA of PSM/VB at T12 (r=0.477, p=0.018). ΔSVA and ΔPT correlated with FI at L4 (r=0.577, p=0.003 and r=-0.407, p=0.048, respectively). DSD group, had weak correlations (-0.3<r<-0.1) between changes in sagittal and PSM parameters. Conclusion: PSM quality in adults with spinal deformity correlates with patients’ ability to maintain an upright posture and sagittal decompensation after walking for 10 minutes.

Incidence of Chronic Periscapular Pain After Adult Thoracolumbar Deformity Correction and Impact on Outcomes

Alexander F. Haddad,Justin K. Scheer,Marissa T. Fury,Justin S. Smith,Vedat Deviren,Christopher P. Ames 대한척추신경외과학회 2021 Neurospine Vol.18 No.3

Objective: Extension of the posterior upper-most instrumented vertebra (UIV) into the upper thoracic (UT) spine allows for greater deformity correction and reduced incidence of proximal junction kyphosis (PJK) in adult spinal deformity (ASD) patients. However, it may be associated with chronic postoperative scapular pain (POSP). The goal of this study was to assess the relationship between UT UIV and persistent POSP, describe the pain, and assess its impact on patient disability. Methods: ASD patients who underwent multilevel posterior fusion were retrospectively identified then administered a survey regarding scapular pain and the Oswestry Disability Index (ODI), by telephone. Univariate and multivariate analysis were utilized. Results: A total of 74 ASD patients were included in the study: 37 patients with chronic POSP and 37 without scapular pain. The mean age was 70.5 years, and 63.9% were women. There were no significant differences in clinical characteristics, including mechanical complications (PJK, pseudarthrosis, and rod fracture) or reoperation between groups. Patients with persistent POSP were more likely to have a UT than a lower thoracic UIV (p= 0.018). UT UIV was independently associated with chronic POSP on multivariate analysis (p=0.022). ODI score was significantly higher in patients with scapular pain (p=0.001). Chronic POSP (p=0.001) and prior spine surgery (p=0.037) were independently associated with ODI on multivariate analysis. Conclusion: A UT UIV is independently associated with increased odds of chronic POSP, and this pain is associated with significant increases in patient disability. It is a significant clinical problem despite solid radiographic fusion and the absence of PJK.