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Based on the designed vibration energy recovery system of speed bump, the structure and principle of a novel transducer are introduced in this paper, which is an important part of the system. AMEsim simulation software was used to study the characteristics of the transducer, and the feasibility of the transducer design was verified through modeling and analysis of the dual-cylinder transducer. The coupling model of vehicle speed bump and transducer was analyzed, the dynamic differential equation was listed, and the decoupling operation was carried out. On the basis of the above, Matlab/Simulink was used to establish the model simulation, and the time-domain responses of displacement, velocity, and acceleration of the vibration of the car body, wheel, and transducer in the coupling model system were analyzed. The control variable method was used to further explore the time-domain response of vehicle acceleration in the coupling system only when the vehicle speed changes or the transducer damping changes. Finally, the vibration energy recovery system of the speed bump was built, and the preliminary test proved that the transducer can realize its function.

We investigate the attosecond transient absorption spectroscopy (ATAS) of graphene by numerically solving four-band density-matrix equations, which demonstrates apparent fish bone resonance structures. To gain insight into these interesting structures, we exploit a simplified model that only considers the electrons of $\Gamma$ and M points in the Brillouin zone. With the help of this model, we can analytically express the ATAS spectrum as the sum of zeroth- and first-order Bessel functions in the variables of the strength and frequency of the infrared pump field as well as the effective mass of electrons at the $\Gamma$ and M points. Lorentzian and Fano line shapes in the absorption spectrum are addressed. The fish bone structure consists of periodic V-shaped structure that can be explained by first-order Bessel functions and its tilt angle is solely determined by the frequency of the pump laser. The periodicity of the V-shaped structure in the fish bone originates from the periodic dependence of the Lorentzian and Fano line shapes of the absorption spectrum on the time delay between the pump and probe lasers. Compared with the numerical results, our analytical theory can qualitatively or even quantitatively predict the zeroth- and first-order fringes in the fish bone structures of the ATAS spectrum. The gauge issues in the numerical simulations are also discussed.

We investigate the high-order harmonic generation in graphene irradiated by a linearly polarized intense laser, addressing the ellipticity or polarization properties of the harmonics. We exploit time-dependent density functional theory to calculate the harmonic spectra for a laser wavelength of 4770 nm and an intensity of 1.7 $\mathrm{TW}/{\mathrm{cm}}^{2}$, and our numerical results can qualitatively reproduce recent experimental data. Our simulations also reveal that the harmonic ellipticity depends on both the harmonic order and the orientation angle between the graphene symmetric axis and the laser polarization direction. It can reach 0.68 for the ninth-order harmonic at the orientation angle of ${20}^{\ensuremath{\circ}}$. To understand the mechanism of the high ellipticity, we develop a two-band model based on the tight-binding approximation. We may explain the ellipticity of high-order harmonic generation by investigating the transition dipole moments in the two-band model. Our theory further predicts a sensitive dependence of the harmonic ellipticity on the laser intensity for various laser wavelengths.

Background Cortical bone trajectory (CBT) has been well-known in spine surgery for obtaining improved fixation while minimizing soft tissue dissection. This study was designed to compare the bone mineral density (BMD) between the CBT and traditional trajectory (TT) by using Hounsfield unit (HU) values and identify the ideal decades of patients and the suitable lumbar segments using this CBT technology from a radiological standpoint. Methods Patients were selected randomly from an institutional database based on age (evenly distributed by a decade of life) and gender. A total of 240 healthy patients had a computed tomography (CT) scan of the chest, abdomen, and pelvis. For each patient, axial slices of every vertebra were cut in two planes: one horizontal to the pedicle representing the plane wherein pedicle screws were inserted using the TT and the other in a caudocranial plane representing the plane wherein pedicle screws were inserted using the CBT. For each trajectory, a region of interest (ROI) was selected within the area wherein the screws were inserted. A CT number (HU values) was then calculated within each ROI to represent bone density. Results HU values measured at the ROI of CBT were significantly greater than those of the traditional pedicle screw in all age groups, and the specific value (ratio of the HU values of CBT/the HU values of TT) between CBT and TT was 1.92. A significant difference was observed between male and female. The HU values of CBT and TT of males were generally higher than those of females (males: CBT/TT 1.89 ± 0.45; Females: CBT/TT 1.95 ± 0.47). The specific value in HU values significantly increased with increasing age (p = 0.000) and cauda lumbar level (p = 0.000) in males and females. Conclusion BMD, as measured by HU values for the ROI of the CBT screw, was significantly greater than that of the traditional pedicle screw, especially in old patients and cauda lumbar segments.

To compare diffusion tensor imaging (DTI) parameters of the spinal cord between patients with cervical spondylotic myelopathy (CSM) and normal subjects, and investigate their significance in the clinical diagnosis, surgical planning and post-operative evaluation of CSM. Routine sequence magnetic resonance imaging (MRI) and DTI scans were performed in 50 normal subjects and 60 cases of CSM with 3.0-T MR. DTI images, apparent diffusion coefficient (ADC) and fractional anisotropy (FA) colormaps corresponding to spinal cord cross-sections were obtained. The spinal cord function of CSM patients was measured using modified Japanese Orthopaedic Association (mJOA) scoring and Nurick grade at different times. The changes in DTI parameters and their correlation with spinal cord function scores were analysed by SPSS 19. There were significant differences in DTI parameters of the spinal cord between normal subjects and patients with CSM (ADC: 1.119 ± 0.087 vs. 1.395 ± 0.091, P

A retrospective study. The objectives of the study were to investigate the predictors for hyponatraemia in patients with cervical spinal cord injuries (CSCIs) and to define the relationship between magnetic resonance imaging (MRI) scans and hyponatraemia. The study was carried out at The First Affiliated Hospital of Anhui Medical University. A total of 292 patients with CSCIs were retrospectively reviewed to determine the predictors of hyponatraemia. Fourteen variables were extracted from the medical records: age, sex, blood pressure (BP), tracheostomy, serum potassium, serum chloride, serum bicarbonate, serum albumin, intravenous fluid intake and urine volume for 24 h, haematocrit, haemoglobin, neurological assessment and four MRI signal patterns. Univariate and multivariate analyses were used to determine the effect of each variable on hyponatraemia. Eighty-two of the 270 patients (30%) developed hyponatraemia. Univariate analyses indicated that the following variables were significant predictors of hyponatraemia: tracheostomy; the initial American Spinal Injury Association (ASIA) Impairment Scale (AIS) A assessment; and haemorrhage changes on T2-weighted MRI scans, and low BP. Multivariate regression analyses revealed two variables were significant predictors of hyponatraemia: haemorrhage changes on T2-weighted MRI scans and low BP. Haemorrhage changes on MRI scans were closely associated with the onset of hyponatremia and could provide objective data for forecasting hyponatraemia in CSCI patients. Low BP was also a reasonable predictor of hyponatremia.

An acidic environment is vital for the maintenance of cellular activities but can be affected tremendously during intervertebral disc degeneration (IVDD). The effect of changes in the acidity of the environment on human nucleus pulposus mesenchymal stem cells (NP-MSCs) is, however, unknown. Thus, this study aimed to observe the biological effects of acidic conditions mimicking a degenerated intervertebral disc on NP-MSCs in vitro. NP-MSCs were isolated from patients with lumbar disc herniation and were further identified by their immunophenotypes and multilineage differentiation. Then, cells were cultured at acidic pH levels (pH 6.2, pH 6.5, pH 6.8, pH 7.1, and pH 7.4) with/without amiloride, an acid-sensing ion channel (ASIC) blocker. The proliferation and apoptosis of NP-MSCs and the expression of stem cell-related genes (Oct4, Nanog, Jagged, Notch1), ASICs, and functional genes (Aggrecan, SOX-9, Collagen-I, and Collagen-II) in NP-MSCs were evaluated. Our work showed that cells obtained from human degenerated NP met the criteria of International Society for Cellular Therapy. Therefore, cells obtained from a degenerated nucleus pulposus were definitively identified as NP-MSCs. Our results also indicated that acidic conditions could significantly inhibit cell proliferation and increase cell apoptosis. Gene expression results demonstrated that acidic conditions could decrease the expression of stem cell-related genes and inhibit extracellular matrix synthesis, whereas it could increase the expression of ASICs. Our study further verified that the above-mentioned biological activities of NP-MSCs could be significantly improved by amiloride. Therefore, the results of the study indicated that the biological behavior of NP-MSCs could be inhibited by acidic conditions during IVDD, and amiloride may meliorate IVDD by improving the activities of NP-MSCs.

Numerous studies have demonstrated the therapeutic effect of bone mesenchymal stem cells on spinal cord injury (SCI), especially on neural stem cells (NSCs). However, the predominant mechanisms of bone mesenchymal stem cells (BMSCs) are unclear. Recently, some researchers have found that paracrine signaling plays a key role in the therapeutic capacity of BMSCs and emphasized that the protective effect of BMSCs may be due to paracrine factors. In this study, we aimed to investigate the potential mechanisms of BMSCs to protect NSCs. NSCs were identified by immunocytochemistry. The oxidative stress environment was simulated by H2 O2 (50, 100, 200 μM) for 2 h. The apoptotic rate of the NSCs was detected via flow cytometry. Lactate dehydrogenase (LDH), malondialdehyde (MDA), and superoxide dismutase (SOD) activity were evaluated via corresponding assay kits. Western blot was used to detect the expressions of Notch1, HES1, caspase-3, cleave caspase-3, Bax, and Bcl-2. We found that H2 O2 could significantly induce the apoptosis of NSCs, increase LDH, MDA levels, and decrease SOD activity by activating the Notch1 signaling pathway. DAPT (the specific blocker of Notch1) and BMSC-conditioned medium (BMSC-CM) could significantly prevent the apoptotic effect and oxidative stress injury on NSCs that were treated with H2 O2 . We also revealed that BMSC-CM could decrease the expression of Notch1, Hes1, cleave caspase-3, Bax, and increases the expression of Bcl-2 in NSCs, which was induced by H2 O2 . These results have revealed that BMSC-CM can neutralize the effect against oxidative stress injury on the apoptosis of NSCs by inhibiting the Notch1 signaling pathway.

OBJECTIVETraditional trajectory (TT) screws are widely used in lumbar fixation. However, they may require revision surgery in some instances, especially in patients with osteoporotic spines. Cortical bone trajectory (CBT) screws may potentially be used to rescue a failed TT screw and vice versa in nonosteoporotic spines. This study aimed to investigate whether a CBT screw can salvage a compromised TT screw in osteoporotic lumbar spines and vice versa.METHODSA total of 42 vertebrae from 17 cadaveric lumbar spines were obtained. Bone mineral density was measured, and a CBT screw was randomly inserted into one side of each vertebra. A TT screw was then inserted into the contralateral side. The biomechanical properties of the screws were tested to determine their insertional torque, pullout strength, and fatigue performance. After checking the screws for the failure of each specimen, the failed screw track was salvaged with a screw of the opposite trajectory. The specimen was then subjected to the same mechanical tests, and results were recorded. A repeat pullout test on TT and CBT screws was also performed.RESULTSWhen CBT screws were used to rescue failed TT screws, the original torque increased by 50%, an average of 81% of the pullout strength of the initial TT screws was retained, and the fatigue performance was equal to that of the original screws, which were considerably stronger than the loose TT screws—that is, the TT repeat screws/TT screws were 33% of the pullout strength of the initial TT screws. When the TT screws were used to salvage the compromised CBT screws, the TT screws retained 51% of the original torque and 54% of the original pullout strength, and these screws were still stronger than the loose CBT screws—that is, the loose CBT screws retained 12% pullout strength of the initial CBT screws. Fatigue performance and the ratio of the pullout strength considerably decreased between the CBT rescue screws and the original CBT screws but slightly changed between the TT rescue screws and the original TT screws.CONCLUSIONSCBT and TT screws can be applied in a revision technique to salvage each other in osteoporotic lumbar spines. Additionally, CBT and TT screws each retain adequate insertional torque, pullout strength, and fatigue performance when used for revision in osteoporotic lumbar spines.

Study design This is a radiographic and cadaveric study. Objective The aim of this study was to conduct a detailed comparison about the parameters between the ideal cortical bone trajectory (CBT) and practical CBT screw. Summary of background data CBT screws have recently become popular in spinal surgery, mainly because of their improved fixation while minimizing soft tissue dissection. However, to our knowledge, no previous study has provided a detailed comparison on the parameters between the ideal CBT and practical CBT screws. Materials and methods The 3-dimensional computed tomography scans of 126 spinal vertebrae separated from 40 lumbar spines were studied. After determining the CBT, the maximal screw length, maximal screw diameter, lateral angle (LA), and cephalad angle (CA) were calculated. Thereafter, CBT screws were inserted into these cadaveric lumbar spines. Subsequently, the lateral angle of screw (LAs) and cephalad angle of screw (CAs) of the screws were measured using 3-dimensional computed tomography. Results As for the ideal CBT, the maximal screw length gradually increased from L1 (32.0 mm) to L4 (35.3 mm) and then decreased at L5 (34.8 mm). Moreover, the maximal screw diameter increased from L1 (4.5 mm) to L5 (7.5 mm). The LA from L1 to L5 were 9.2, 9.4, 9.9, 11.2, and 12.0 degrees, respectively. The CA from L1 to L5 were 25.8, 25.8, 26.3, 26.8, and 26.0 degrees, respectively. As for the actual CBT screw, the LAs from L1 to L5 were 12.7, 14.1, 13.2, 12.4, and 13.0 degrees, respectively. The CAs from L1 to L5 were 25.4, 27.5, 29.2, 30.1, and 30.5 degrees, respectively. Significant differences were observed between the angles of the ideal trajectory and the actual screw. Conclusions Parameters of the actual CBT screw are slightly larger than the optimal trajectory measurements. The CAs and LAs are ∼25-30 and 10-16 degrees, respectively. L1 and L2 should be given considerable attention when using the CBT technique. And the trajectory measurements can only be used as a guide in clinical practice.

Objective Selecting optimal strategies for improving fixation in osteoporotic lumbar spine is an important issue in clinical research. Cortical bone trajectory (CBT) screws have been proven to enhance screw pullout strength, but biomechanical efficacy of these screws remains understudied. The aim of this study was to evaluate biomechanical efficacy of CBT screws in osteoporotic lumbar spine. Methods Thirty-one vertebrae from 14 cadaveric lumbar spines were obtained. All specimens were measured by computed tomography; the diameter of pedicles, excluding those of vertebral bodies with very small pedicle developments, was calculated. After measuring bone mineral density, the CBT screw was randomly inserted into 1 side, and the traditional trajectory (TT) screw was inserted into the contralateral side. Maximum insertional torque was recorded after screw insertion. Of vertebrae, 21 were subjected to pullout testing at a rate of 5 mm/minute, and 10 were subjected to cyclic fatigue testing. Each construct was loaded until exceeding 5 mm. Results Average bone mineral density was 0.567 ± 0.101 g/cm2. CBT screws had higher maximum insertional torque (degrees of freedom = 30, t = 5.78, P Conclusions CBT screws had better biomechanical fixation in osteoporotic lumbar spine compared with standard pedicle screws.

Neural stem cells (NSCs) have emerged as a promising treatment for spinal cord injuries. However, the increasing expression of bone morphogenetic proteins (BMPs) in spinal cord injury lesion sites seems to have contributed to the limited oligodendroglial differentiation and the majority of the astroglial differentiation of NSCs. In the present study, we demonstrate that BMPs promote NSCs differentiation toward astrocytes and prevent them from differentiating into oligodendrocytes. This effect is accompanied by the increasing expression of Id2 and the reduction in Oilg1/2 expression. Treatment with bone marrow stromal cells (BMSCs) can enhance the development of oligodendrocytes in the presence of BMPs. The analysis of Id2, as well as Olig1 and Olig2 gene expression, reveals that the effect of BMPs on these gene expressions is reversed with the addition of BMSCs. In sum, these data strongly suggest that BMSCs can promote the differentiation of NSCs into oligodendrocytes through mediating Id2 and Olig1/2 expression by blocking the BMP/Smad signaling pathway.

A persistent challenge in spine surgery is improving screw fixation in patients with poor bone quality. Augmenting pedicle screw fixation with allograft bone appears to be a promising approach.To evaluate the biomechanical properties of screws augmented or revised with allograft bone particles (ABPs) and the effect of different sizes and amounts of ABP on screw-fixation strength.Biomechanical in vitro study.Sixty vertebrae were separated randomly into six groups. Groups A1 and A2: one pedicle of each vertebra was selected randomly to be the original pedicle and implanted with a screw. Then, biomechanical tests were performed. Subsequently, the failed trajectory was revised with 1 mm ABP, and the contralateral pedicle was augmented with the same size and amount of ABP. Groups B1 and B2: two pedicles of each vertebra were augmented with different amounts of 1 mm ABP. Groups C1 and C2: one pedicle of each vertebra was augmented with 1 mm ABP to the maximum. The contralateral pedicle of each vertebra was augmented with the same amount of 2 mm ABP. After augmentation and screw insertion, groups A1, B1, and C1 were subjected to the pullout test, whereas groups A2, B2, and C2 the cyclic fatigue test.Groups A1 and A2: screw augmentation increased the pullout strength by 47%, cycles to failure by 31%, and failure loads by 21% compared with the screw in the original pedicle (p.05). Screw revision obtained 79% pullout strength, 97% cycles to failure, and 98% failure loads of the screw in the original pedicle (p.05). Groups B1 and B2: full (100%) trajectory augmentation increased the pullout strength by 39%, cycles to failure by 18%, and failure loads by 12% compared with half (50%) trajectory augmentation (p.05). Groups C1 and C2: the values of the pullout strength, cycles to failure, and failure loads of the screw augmented with 1 mm ABP were all greater than those in the 2 mm ABP. However, no significant differences were observed between the two treatments (p.05).Trajectory augmentation with ABP can significantly increase the strength of the augmented screws. Full trajectory augmentation can provide greater strength compared with half trajectory augmentation. In patients with osteoporosis, we recommend using 1 mm ABP in full trajectory augmentation (0.3 g ABP for 5.5 mm×40 mm and 0.5 g ABP for 6.5 mm×45 mm) before trajectory fails.

To compare volume-occupying rate of cervical spinal canal between patients with cervical spondylotic myelopathy (CSM) and normal subjects, and to investigate its significance in cervical spine disease.Spiral computed tomography (CT) scan (C4-C6 cervical spine unit) was performed in 20 normal subjects and 36 cases of CSM at a neutral position, and data were transferred to the Advantage Workstation Version 4.2 for assessment. Bony canal area and fibrous canal area in each cross section, and sagittal diameters of cervical spinal canal and cervical spinal body were measured. Volume-occupying rate of cervical spinal canal was calculated using MATLAB. Cervical spinal canal ratio and effective cervical spinal canal ratio were calculated, and Japanese Orthopaedic Association score was used to assess cervical spinal cord function.Volume-occupying rate of cervical spinal canal at a neutral position was significantly higher in CSM patients as compared to normal subjects (P 0.01). There was no correlation between cervical spinal canal ratio and JOA score in CSM patients, with a Pearson's correlation coefficient of 0.171 (P 0.05). However, sagittal diameter of secondary cervical spinal canal, effective cervical spinal canal ratio and volume-occupying rate of cervical spinal canal were significantly associated to JOA score, with Pearson's coefficient correlations of 0.439 (P 0.05), 0.491 (P 0.05) and -0.613 (P 0.01), respectively.Volume-occupying rate of cervical spinal canal is an objective reflection of compression on cervical spine and spinal cord, and it is associated with cervical spinal cord function. These suggest that it may play a significant role in predicting the development of CSM.

Retrospective chart audit.This study aims to compare the clinical features and surgical outcomes in patients with cervical spondylotic myelopathy (CSM) among different age groups.The first Affiliated Hospital of Anhui Medical University, China.A total of 460 patients with CSM who were surgically treated over the period of 1995-2009 were investigated. Considering the peak age (40-60 years old) for the onset of symptoms, we divided the patients into three groups by age: young (40), middle-aged (40-60), and old (60). The differences in symptoms, symptom durations, involved levels, surgical approaches and outcomes were evaluated.The number of symptoms and involved levels, symptom duration and posterior approach significantly increased with increasing age, whereas preoperative Japanese Orthopedic Association score decreased among the three groups. Spinal cord function improved after surgery in all groups. The highest degree of recovery occurred during the first 6 months after surgery, especially within the first week, and then reached a plateau. After 6 months, however, recovery continuously improved, stabilized and declined in the young, middle-aged, old groups, respectively. The recovery rate was not significantly different at an immediate period (1 week) after operation among the three groups, but was significantly different at later periods (3 or more months postoperatively). Three groups showed no difference in postoperative complication rates.The severity of CSM increased with increasing age. Age was inversely correlated with recovery, and recovery decreased as age increased. Six months post operation was the prime time for the recovery of spinal cord function.

We investigate the polarization properties of below-threshold harmonics from aligned molecules in linearly polarized laser fields numerically and analytically. We focus on lower-order harmonics (LOHs). Our simulations show that the ellipticity of below-threshold LOHs depends strongly on the orientation angle and differs significantly for different harmonic orders. Our analysis reveals that this LOH ellipticity is closely associated with resonance effects and the axis symmetry of the molecule. These results shed light on the complex generation mechanism of below-threshold harmonics from aligned molecules.

Objective To investigate the variation of pelvic radius and related parameters in low-grade isthmic lumbar spondylolisthesis. Methods Seventy-four patients with isthmic lumbar spondylolisthesis and 47 controls were included in this study. There were 17 males and 57 females between 30 and 66 years of age, including 30 with grade I slippages and 44 grade II slippages; diseased levels included 34 cases on L4 and 40 cases on L5. Thoracic kyphosis (TK), the pelvic radius (PR), the pelvic angle (PA), pelvic morphology (PR-S1), and total lumbopelvic lordosis (PR-T12) were assessed from radiographs. Results Statistically significant differences were found for the PA, PR-T12, and PR-S1 (24.5±6.6°, 83.7±9.8°, and 25.4±11.2°, respectively) of the patients with spondylolisthesis and the healthy volunteers (13.7±7.8°, 92.9±9.2°, and 40.7±8.9°, respectively). The TK/PR-T12 ratios were between 0.15 and 0.75. However, there were no differences in all the parameters between the L4 and L5 spondylolysis subgroups (p>0.05). The TK and PR-S1 of grade II were less than grade I, but the PA was greater. The PR-T12 of female patients were less than male patients, but the PA was greater (p Conclusion Pelvic morphology differed in patients with low-grade isthmic lumbar spondylolisthesis compared to controls. Gender and the grade of slippage impacted the sagittal configuration of the pelvis, but the segment of the vertebral slip did not. Overall, the spine of those with spondylolisthesis remains able to maintain sagittal balance despite abnormal pelvic morphology.

We study the influence of pulse duration on high harmonic generation (HHG) by exploring a wide laser-parameter region theoretically. Previous studies have shown that for high laser intensities close to saturation ionization intensity, the HHG inversion efficiency is higher for shorter pulses since the ground-state depletion is weaker in short pulses. Our simulations show that this high efficiency also appears for a moderate laser intensity at which the ionization is not very strong. A classical effect relating to shorter travel distances of the rescattering electron in shorter pulses is shown to contribute importantly to this high efficiency. The effect can be amplified significantly if a two-color laser field is used, suggesting a potential approach to increasing the HHG yield and generating short and bright attosecond pulses.

Objective: Vitamin D receptor (VDR) gene polymorphisms may be associated with the risk of OA, however, evidence for this is controversial. This meta-analysis aims to confirm whether VDR gene polymorphisms are associated with OA. Methods: Meta-analyses on the association between OA and VDR ApaI, BsmI, TaqI and FokI polymorphisms were conducted using allele and homozygote contrast and contrasts in the recessive and dominant models. Stratification analyses by different demographic regions (Europe vs Asian) were also performed and pooled odds ratios (ORs) were obtained using the random effects model if the results were heterogeneous.Results. A total of 13 relevant studies involving OA patients (n = 2104) and controls (n = 2939) were included in the analysis. There were significant associations between VDR ApaI polymorphisms and OA in the Asian population (A vs a: OR = 1.16, 95% CI 1.02, 1.32, P = 0.025; AA vs Aa/aa: OR = 1.36, 95% CI 1.04, 1.77, P = 0.025; AA vs aa: OR = 1.35, 95% CI 1.00, 1.80, P = 0.047), but not in the whole population. There was also a statistically significant association between FokI polymorphism and OA (FF vs Ff/ff: OR = 0.65, 95% CI 0.44, 0.95, P = 0.024); however, this result was derived from only two studies. No significant associations were found between VDR TaqI and BsmI polymorphisms and OA. Conclusion: There are modest but statistically significant associations between VDR ApaI polymorphisms and the susceptibility of OA in the Asian population. © The Author 2014. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved.

To evaluate the effect of anterolateral approach in treating thoracolumbar disc protrusion.From May 2004 to May 2008, 11 patients with thoracolumbar disc protrusion (T10-L3) underwent discectomy, autologous iliac bone graft, and internal fixation via anterolateral approach. There were 9 males and 2 females aged 26-57 years old (average 42.8 years old). The course of disease was 1 week-11 years (average 2.7 years). Nine patients showed the lower limbs weakness, 8 had sensory disturbance, 6 presented with lumbodorsal pain, 5 had the lower limb pain, 4 presented with sphincter muscle disturbance, 3 suffered from foot drop, and 5 had a history of lower back injury. X-ray, CT, and MRI test showed that 9 cases had the single-segmental protrusion, 2 cases had double-segmental protrusion, 2 cases were accompanied with ossification of the thoracic vertebra yellow ligament, 2 cases were combined with ossification of the vertebra posterior longitudinal ligament, and 1 was complicated with Scheuermann disease. Preoperatively, the intervertebral height was (7.2 +/- 1.3) mm and JOA score was 6.4 +/- 2.8.The time of operation was 2.5-5.5 hours (average 3.5 hours); the blood loss during operation was 500-1,200 mL (average 750 mL). During operation, intraoperative pleural tear occurred in 1 patient, peritoneal tear in 1 patient, and dural laceration in 1 patient. Repairing was performed intraoperative and preventive suction drainage was used for 3-5 days. No postoperative hydropneumothorax and cerebrospinal fluid leakage occurred. All incisions healed by first intention. No postoperative complications of nerve system occurred. All the patients were followed up for 1-4 years (average 2.4 years). X-ray films showed that all the patients achieved bony fusion without the occurrence breakage and loosening of titanium plate and screw 6-9 months after operation. Three cases displayed subtle scoliosis (10-15 degrees) without influence on spinal equilibration. The intervertebral height increased to (12.3 +/- 1.5) mm 2 weeks after operation, indicating there was a significant difference compared with preoperative value (P0.05). The intervertebral height 1 year after operation when the bony fusion was reached decreased to (7.5 +/- 1.2) mm, indicating there was no significant difference compared to the preoperative value (P0.05). The JOA score increased to 7.6 +/- 3.2 at 1 year after operation, indicating there was a significant difference compared with preoperative value (P0.05). The symptoms and signs of all the patients were improved to various degrees after operation. According to improvement rate evaluation system proposed by Hirabayashi et al., 4 cases were graded as excellent, 6 as good, 1 as fair, and the excellent and good rate was 90.9%.Treating thoracolumbar disc protrusion via anterolateral approach is safe and effective.

We study the ellipticity of near-threshold harmonics (NTH) from aligned molecules with large internuclear distances numerically and analytically. The calculated harmonic spectra show a broad plateau for NTH which is several orders of magnitude higher than that for high-order harmonics. In particular, the NTH plateau shows high ellipticity at small and intermediate orientation angles. Our analyses reveal that the main contributions to the NTH plateau come from the transition of the electron from continuum states to these two lowest bound states of the system, which are strongly coupled together by the laser field. Besides continuum states, higher excited states also play a role in the NTH plateau, resulting in a large phase difference between parallel and perpendicular harmonics and accordingly high ellipticity of the NTH plateau. The NTH plateau with high intensity and large ellipticity provides a promising manner for generating strong elliptically-polarized extreme-ultraviolet (EUV) pulses.