Adjacent Angles Research Articles

Objectifying the adjacent and opposite angles: a cultural historical analysis

ABSTRACTThe angle topic is central to the development of geometric knowledge. Two of the basic concepts associated with this topic are the adjacent and opposite angles. It is the goal of the present study to analyze, based on the cultural historical semiotics framework, how high-achieving seventh grade students objectify the adjacent and opposite angles’ concepts. We videoed the learning of a group of three high-achieving students who used technology, specifically GeoGebra, to explore geometric relations related to the adjacent and opposite angles’ concepts. To analyze students’ objectification of these concepts, we used the categories of objectification of knowledge (attention and awareness) and the categories of generalization (factual, contextual and symbolic), developed by Radford. The research results indicate that teacher's and students’ verbal and visual signs, together with the software dynamic tools, mediated the students’ objectification of the adjacent and opposite angles’ concepts. Specifically, eye and gestures perceiving were part of the semiosis cycles in which the participating students were engaged and which related to the mathematical signs that signified the adjacent and the opposite angles. Moreover, the teacher's suggestions/requests/questions included/suggested semiotic signs/tools, including verbal signs that helped the students pay attention, be aware of and objectify the adjacent and opposite angles’ concepts.

Soft tissue artefacts of skin markers on the lower limb during cycling: Effects of joint angles and pedal resistance.

Soft tissue artefacts (STA) are a major error source in skin marker-based measurement of human movement, and are difficult to eliminate non-invasively. The current study quantified in vivo the STA of skin markers on the thigh and shank during cycling, and studied the effects of knee angles and pedal resistance by using integrated 3D fluoroscopy and stereophotogrammetry. Fifteen young healthy adults performed stationary cycling with and without pedal resistance, while the marker data were measured using a motion capture system, and the motions of the femur and tibia/fibula were recorded using a bi-plane fluoroscopy-to-CT registration method. The STAs with respect to crank and knee angles over the pedaling cycle, as well as the within-cycle variations, were obtained and compared between resistance conditions. The thigh markers showed greater STA than the shank ones, the latter varying linearly with adjacent joint angles, the former non-linearly with greater within-cycle variability. Both STA magnitudes and within-cycle variability were significantly affected by pedal resistance (p<0.05). The STAs appeared to be composed of one component providing the stable and consistent STA patterns and another causing their variations. Mid-segment markers experienced smaller STA ranges than those closer to a joint, but tended to have greater variations primarily associated with pedal resistance and muscle contractions. The current data will be helpful for a better choice of marker positions for data collection, and for developing methods to compensate for both stable and variation components of the STA.

Percutaneous Endoscopic Cervical Discectomy (PECD): An Analysis of Outcome, Causes of Reoperation.

Percutaneous endoscopic cervical discectomy (PECD) is regarded as an effective treatment modality in cervical disc herniation, including radicular pain and lateral location of disc herniation. This study aimed to evaluate the clinical and radiologic outcomes of PECD along with the causes of reoperation and the technique itself. Between January 2007 and November 2012, 101 patients underwent PECD at the Busan Wooridul Hospital. Three patients underwent a 2-level PECD. The mean follow-up period was 34 months (range, 18-72 months). The mean age was 46.1 years; the most common operation was at the C5-C6 level (n= 45), followed by C6-C7 (n=35), C4-C5 (n= 16), and C3-C4 (n= 8). The clinical outcomes were evaluated via the visual analog scale of the neck and arm according to the Neck Disability Index and the modified Macnab criteria. Among 101 patients, 12 underwent an additional operation at the index level. Five patients had aggravated stenosis by disc height narrowing, 4 had recurred disc, 2 had remained disc, and 1 had sustained symptoms. After PECD, there was a significant improvement in the visual analog scale and Neck Disability Index scores (P < 0.001). According to the modified Macnab criteria, excellent concordance was achieved in 65 patients, good in 22, fair in 2, and poor in 12. The reoperation performed on 12 patients improved their clinical outcomes. The mean duration was 4.8 months (2 days to 18 months) until reoperation. There were 3 PECD revisions, 3 artificial disc replacements, 2 corpectomies, 2 anterior cervical discectomies and fusion with cages, and 2 transfers to another hospital. The common feature was older age (P=0.016) and male sex (P= 0.031). Preoperative radiologic findings were characterized by the foraminal disc (P= 0.04), disc degeneration at the index level (P=0.05), combined bony spur (P= 0.001), concomitant adjacent level degeneration (P= 0.019), cervical kyphosis (P= 0.015), and segmental angle deterioration after PECD (P= 0.038). No statistical correlation was seen between the operation level and herniation size (P > 0.05). In total, 87% patients showed successful clinical outcome. Poor and fair outcomes at initial PECD were overcome by revision surgery, which improved outcomes. Although PECD is a promising minimally invasive procedure for cervical disc treatment, the indications for PECD should be considered carefully.

Preconditioned prestack plane-wave least squares reverse time migration with singular spectrum constraint

Least squares migration can eliminate the artifacts introduced by the direct imaging of irregular seismic data but is computationally costly and of slow convergence. In order to suppress the migration noise, we propose the preconditioned prestack plane-wave least squares reverse time migration (PLSRTM) method with singular spectrum constraint. Singular spectrum analysis (SSA) is used in the preconditioning of the take-offangle-domain common-image gathers (TADCIGs). In addition, we adopt randomized singular value decomposition (RSVD) to calculate the singular values. RSVD reduces the computational cost of SSA by replacing the singular value decomposition (SVD) of one large matrix with the SVD of two small matrices. We incorporate a regularization term into the preconditioned PLSRTM method that penalizes misfits between the migration images from the plane waves with adjacent angles to reduce the migration noise because the stacking of the migration results cannot effectively suppress the migration noise when the migration velocity contains errors. The regularization imposes smoothness constraints on the TADCIGs that favor differential semblance optimization constraints. Numerical analysis of synthetic data using the Marmousi model suggests that the proposed method can efficiently suppress the artifacts introduced by plane-wave gathers or irregular seismic data and improve the imaging quality of PLSRTM. Furthermore, it produces better images with less noise and more continuous structures even for inaccurate migration velocities.

Enhanced sulfur removal by a tuned composite structure of Cu, Zn, Fe, and Al elements

Several combinations of high sulfur affinity elements of Cu, Zn, Fe, and Al were used to prepare sorbent materials that remove hydrogen sulfide (H2S) from air contaminated streams. The combination of these four elements in composite crystallinity structure resembling hydrotalcite-like and aurichalcite-like compounds showed excellent H2S uptake. Further tuning of the relative ratio among these elements resulted in outstanding H2S uptake. XRD revealed that the final sorbent material was featured by crystallinity structure that had two adjacent lower reflection angles. The experimental test showed H2S uptake was around 39% of the sorbent material weight when the concentration of H2S in the outlet was less than 0.5% of its concentration in the inlet. The sorbent material showed high sulfur removal efficiency at ambient temperature without prior calcination.

The relationship between changes of cervical sagittal alignment after anterior cervical discectomy and fusion and spino-pelvic sagittal alignment under roussouly classification: a four-year follow-up study

BackgroundAnterior cervical discectomy and fusion (ACDF) is widely used in the treatment of cervical degenerative disease; however, the variation of cervical sagittal alignment changes after ACDF has been rarely explored. The purpose of this study is to determine the relationship between changes of cervical sagittal alignment after ACDF and spino-pelvic sagittal alignment under Roussouly classification.MethodsA cohort of 133 Chinese cervical spondylotic patients who received ACDF from 2011 to 2012 was recruited. All patients were categorized with Roussouly Classification. Lateral X-ray images of global spine were obtained, and preoperative and postoperative parameters were measured and analyzed, including C2–C7 angles (C2–C7), C0–C7 angles (C0–C7), external auditory meatus (EAM) tilt, sacral slope (SS), thoracic kyphosis (TK), lumbar lordosis (LL), spinal sacral angles (SSA), Superior adjacent inter-vertebral angle (SAIV), inferior adjacent inter-vertebral angle (IAIV) and et al. The Wilcoxon signed-rank test was used for intragroup comparisons preoperatively and at postoperative 48 months.ResultsAmong the parameters, C2–C7 and C0–C7 showed significant increase, while EAM TK, and IAIV decreased significantly. In type I, EAM and TK decreased significantly, however SS showed a significant increase; in type II, TK showed a significant decrease, but SSA showed a significant increase; in type III, a significant increase of C0–C7 was observed with a significant decrease in EAM, nevertheless, LL, SS and SSA showed significant decreases; and in type IV, C2–C7 showed a significant increase and EAM decreased significantly. The percentage of lordotic alignment in cervical spine increased, which was presenting in type I, III and IV. Nevertheless, the amount of patients with straight cervical alignment increased in type II.ConclusionThe backward movement of head occurs is the compensatory mechanism in cervical sagittal alignment modifications after ACDF. The compensatory alteration of spino-pelvic sagittal alignment varied in different Roussouly type.

Planning 4D intensity-modulated arc therapy for tumor tracking with a multileaf collimator

This study introduces a practical four-dimensional (4D) planning scheme of IMAT using 4D computed tomography (4D CT) for planning tumor tracking with dynamic multileaf beam collimation. We assume that patients can breathe regularly, i.e. the same way as during 4D CT with an unchanged period and amplitude, and that the start of 4D-IMAT delivery can be synchronized with a designated respiratory phase. Each control point of the IMAT-delivery process can be associated with an image set of 4D CT at a specified respiratory phase. Target is contoured at each respiratory phase without a motion-induced margin. A 3D-IMAT plan is first optimized on a reference-phase image set of 4D CT. Then, based on the projections of the planning target volume in the beam’s eye view at different respiratory phases, a 4D-IMAT plan is generated by transforming the segments of the optimized 3D plan by using a direct aperture deformation method. Compensation for both translational and deformable tumor motion is accomplished, and the smooth delivery of the transformed plan is ensured by forcing connectivity between adjacent angles (control points). It is envisioned that the resultant plans can be delivered accurately using the dose rate regulated tracking method which handles breathing irregularities (Yi et al 2008 Med. Phys. 35 3955–62).This planning process is straightforward and only adds a small step to current clinical 3D planning practice. Our 4D planning scheme was tested on three cases to evaluate dosimetric benefits. The created 4D-IMAT plans showed similar dose distributions as compared with the 3D-IMAT plans on a single static phase, indicating that our method is capable of eliminating the dosimetric effects of breathing induced target motion. Compared to the 3D-IMAT plans with large treatment margins encompassing respiratory motion, our 4D-IMAT plans reduced radiation doses to surrounding normal organs and tissues.

On the equivalence of Alexandrov curvature and Busemann curvature

It is shown that the curvature bounded above (resp. below) in the sense of Alexandrov is equivalent to the curvature bounded above (resp. below) in the sense of Busemann if and only if the sum of adjacent average angles is at least (resp. at most) $\pi$.

Experimental study of the influence of ply orientation on DCB mode-I delamination behavior by using multidirectional fully isotropic carbon/epoxy laminates

The influence of ply orientation on the resistance to mode I delamination of multidirectional composite laminates can be assessed by Double Cantilever Beam (DCB) tests. However, one difficulty is to uncouple the global and local effects due to the stacking sequence, which is necessary for a conclusive analysis. In the present work six multidirectional DCB specimens were designed so as to obtain an uncoupled fully isotropic elastic behavior, with the same properties for the entire laminate and the two sub laminates separated by the pre-crack at mid-plane. These specimens have different ply orientations, but their elastic properties are exactly the same. Hence differences in mode I delamination behavior are only due to local fiber orientation effects. Experimental results show that the measured toughness at the crack initiation decreases with both adjacent and sub-adjacent ply angles. During the crack propagation, the plateau value of the R-curve increases with the ply angle of adjacent plies.

Influence of entrance geometry on flow field and heat transfer performance in stationary two-pass smooth parallelogram channels

PIV and Infrared Thermometry measurements are respectively conducted to study the effects of entrance geometry and Reynolds number (Re) on the detailed flow fields and local temperature distributions in a stationary two-pass smooth parallelogram channel with 180-deg sharp turn. Two entrance geometries, including a fully developed inlet condition (FDI) as well as an asymmetrically and suddenly contracted inlet condition (ASI), are investigated. The smooth parallelogram channel has equal adjacent sides of 45.5mm in length and two pairs of adjacent angles are 45-deg and 135-deg. Local (Nu0) and regionally averaged (Nu‾0) Nusselt numbers over entire top and bottom walls along the first and second passages and through the bend region with the associated pressure drop are examined under Re ranging from 5000 to 20,000. Moreover, cross-sectional secondary-flow patterns as well as the near-wall streamwise mean velocity components and turbulent kinetic energy are analyzed to correlate the relationship between flow characteristics and heat transfer distributions at Re=10,000. The most distinct finding of the present study is that the asymmetric thermal and fluid flow features on the top and bottom wall side, in contrast to symmetric ones in the corresponding square and rectangular channels. The affected top and bottom wall Nu0 distributions of ASI respectively extends downstream to the mid-turn and the middle of second pass. Compared with FDI, ASI elevates the Nu‾0 about 65.3–70.1%, 14.2–13.7%, and 23.9–14.0% in the first passage, turn region, and second passage, respectively, under constant flow rate condition. Thermal performance factors of the ASI are about 43.5% and 53.7% higher than the FDI at Re=5000 and 20,000, respectively. Moreover, the correlations of Nu0 and fanning friction factor (f0) with Re are obtained and further compared with those of the corresponding square channels available from the literature.

Progressive damage modelling of hybrid RTM-made composite Π-joint under four-point flexure using mixed failure criteria

This paper deals with four-point flexure tests on hybrid Π-joints, made out of multi-layer carbon fiber/epoxy resin reinforced composites, processed using the RTM (resin transfer moulding) technique. Static bending properties and failure mechanism were determined by experimental observations. Failure of the Π-joints in four-point flexure tests was through interlaminar debonding in triangular zone followed by debonding propagation along the interface between the triangular zone and the adjacent boundary angle until complete breakage of the top skin. A progressive damage model (PDM) based on mixed failure criteria was developed to predict failure loads. Good correlation was achieved between experimental and numerical results.

Radiographic evaluation of posterior selective thoracolumbar or lumbar fusion for moderate Lenke 5C curves

IntroductionPosterior selective thoracolumbar or lumbar (TL/L) fusion with pedicle screw constructs for adolescent idiopathic scoliosis (AIS) has been studied in a few researches. However, few studies have discussed the indication for selective TL/L fusion and the behaviors of its adjacent disc angle. The present study aims to discuss the indication for posterior selective TL/L fusion and the behavior of the adjacent disc angle.Methods45 consecutive cases of AIS undergoing posterior selective TL/L fusion were retrospectively evaluated, with an average follow-up of 36 months. Radiographs were reviewed to determine the coronal curve magnitude and the sagittal alignment preoperatively, postoperatively and at final follow-up. Thoracic curves in groups A had a correction loss of more than 5°, while thoracic curves in group B had a correction loss of not more than 5°.ResultsThe coronal curve magnitude of the TL/L curve averaged 44° preoperatively and it was corrected to 6° immediately with a correction rate of 84.8 %. At final follow-up it was 9° with a correction loss of 3°. The minor thoracic curve was 26° preoperatively, and the convex side bending curve magnitude averaged 8° with a flexibility of 72.7 %. It was corrected to 13° immediately with a spontaneous correction of 48.5 %. At final follow-up it was 14° with a correction loss of 1°. UIVA decreased from 4° to 2° after surgery, and it was 2° at final follow-up. LIVA decreased from 7° to 4° after surgery, and it was 5° at final follow-up. Maximal correction of TL/L curves in group A is significantly less than that in group B. 1 patient received revision surgery to fuse the progressive thoracic curve.ConclusionPosterior selective TL/L fusion with pedicle screw constructs allows for spontaneous thoracic correction and maintains coronal and sagittal balance during the follow-up. Maximal correction instead of undercorrection was recommended for moderate Lenke 5C curves. Disc wedging could be improved after surgery and well maintained during the follow-up.

Topological Gaussian ARTs with Short-Term and Long-Term Memory for Map Building and Fuzzy Motion Planning

This paper proposes a cognitive architecture for building a topological map incrementally inspired by beta oscillations during place cell learning in hippocampus. The proposed architecture consists of two layer: the short-term memory layer and the long-term memory layer. The short-term memory layer emulates the entorhinal and the ? is the orientation system; the long-term memory layer emulates the hippocampus. Nodes in the topological map represent place cells (robot location), links connect nodes and store robot action (i.e. adjacent angle between connected nodes). The proposed method is formed by multiple Gaussian Adaptive Resonance Theory to receive data from various sensors for the map building. It consists of input layer and memory layer. The input layer obtains sensor data and incrementally categorizes the acquired information as topological nodes temporarily (short-term memory). In the long-term memory layer, the categorized information will be associated with robot actions to form the topological map (long-term memory). The advantages of the proposed method are: 1) it is a cognitive model that does not require human defined information and advanced knowledge to implement in a natural environment; 2) it can generate the map by processing various sensors data simultaneously in continuous space that is important for real world implementation; and 3) it is an incremental and unsupervised learning approach. Thus, the authors combine their Topological Gaussian ARTs method (TGARTs) with fuzzy motion planning to constitute a basis for mobile robot navigation in environment with slightly changes. Finally, the proposed approach was verified with several simulations using standardized benchmark datasets and real robot implementation.

SU-F-R-28: Correction of FCh-PET Bladder Uptake Using Virtual Sinograms and Investigation of Its Impact On the Quantification of Prostate Textural Characteristics

Purpose: Textural biomarkers as a tool for quantifying intratumoral heterogeneity hold great promise for diagnosis and early assessment of treatment response in prostate cancer. However, spill-in counts from the bladder uptake are suspected to have an impact on the textural measurements of the prostate volume. This work proposes a correction method for the FCh-PET bladder uptake and investigates its impact on intraprostatic textural properties. Methods: Two patients with PC received pre-treatment dynamic FCh-PET scans reconstructed at four time points (interval: 2 min), for which prostate and bladder contours were obtained. Projection bins affected by bladder uptake were determined by forward-projection. For each time point and axial position, virtual sinograms were obtained and affected bins replaced by a weighted combination of original values and values interpolated using cubic spline from non-affected bins of the current and adjacent projection angles. The process was optimized using a genetic algorithm in terms of minimization of the root-mean-square error (RMSE) within the bladder between the corrected dynamic time point volume and a reference initial uptake volume. Finally, the impact of the bladder uptake correction on the prostate region was investigated using two standard SUV metrics (1) and three texture metrics (2): 1) SUVmax, SUVmean; 2) Contrast, Homogeneity, Coarseness. Results: Without bladder uptake correction, SUVmax and SUVmean were on average overestimated in the prostate by 0%, 0%, 33.2%, 51.2%, and 3.6%, 6.0%, 2.9%, 3.2%, for each time point respectively. Contrast varied by −9.1%, −6.7%, +40.4%, +107.7%, and Homogeneity and Coarseness by +4.5%, +1.8%, −8.8%, −14.8% and +1.0%, +0.5%, −9.5%, +0.9%. Conclusion: We proposed a method for FCh-PET bladder uptake correction and showed an impact on the quantification of the prostate signal. This method achieved a large reduction of intra-prostatic SUVmax while minimizing the impact on SUVmean. Further investigation is necessary to interpret changes in textural features. SL acknowledges partial support by the CREATE Medical Physics Research Training Network grant of the Natural Sciences and Engineering Research Council (Grant number: 432290).

Effects of light source on the performance of a Kretschmann surface plasmon resonance sensor

The effects of light source are usually neglected in most surface plasmon resonance sensors for indoor operations. However they should not be ignored in high precision applications. This paper further analyzes the light source parameters, including peak wavelength, divergence angle and spectral linewidth, by using a modified Gauss distribution assumption in a Kretschmann configuration surface plasmon resonance sensor. A light beam with a specific divergence angle or linewidth can be expressed as the superposition of lights with a range of adjacent incident angles or continuous monochromatic lights. Theoretical modelling and calculation show that an increase of wavelength reduces resonance angle. Both light beam divergence angle and spectral linewidth are proportional to the shift of resonance angle. Our experiments accordingly demonstrate that the change of wavelength from 632.8 nm to 852.4 nm cause a 1.51° decrease in the resonance angle, and a divergence angle increment of 3.9° leads to about 1.21° increment in the resonance angle.

Is it enough to stop distal fusion at L3 in adolescent idiopathic scoliosis with major thoracolumbar/lumbar curves?

The choice of distal fusion level in adolescent idiopathic scoliosis (AIS) patients with major thoracolumbar or lumbar (TL/L) curves (Lenke type 3C, 5C, or 6C) remains debatable. One of the most controversial issues involves stopping the distal fusion at L3, which might result in an increased risk of decompensation but save more mobile spinal segments. The purpose of this study was to evaluate and compare the clinical and radiological outcomes of corrective surgery for AIS with major TL/L curves according to the distal fusion level. 229 AIS patients with Lenke type 3C, 5C, or 6C curves that underwent corrective surgery were included. Patients were grouped according to distal fusion level, either L3 (group A) or L4 (group B), and followed up for over 2years. Group A was further divided into lower end vertebra (LEV) and last touching vertebra (LTV). The SRS-22 score was used to assess clinical outcomes. All radiological parameters were assessed pre- and postoperatively by standing anteroposterior whole-spine radiographs. Clinical and radiological parameters were compared between the groups. Postoperative decompensation was found in 4.6% (9/197) of group A patients and 9.3% (3/32) of group B patients. This difference was not statistically significant (P=0.258). No difference was found in the clinical and radiological parameters between the two groups either pre- or postoperatively. Subgroup analysis showed that the scoliosis correction rate and postoperative apical vertebral translation were lower in cases with an LEV≤L4 or LTV=L5 when the fusion stopped at L3 distally. The adjacent disc wedge angle was aggravated postoperatively in these cases, although this did not reach statistical significance. There is no difference in the radiological and clinical outcomes in AIS according to the distal fusion level. Major TL/L curve correction in AIS may be sufficient distally at L3 in cases with an LEV≥L3 and LTV≥L4. However, stopping fusion at L3 requires caution in LEV≤L4 or LTV=L5 patients, as this correction rate might be suboptimal and causes a possible progression of the adjacent disc wedge angle.

An interprojection sensor fusion approach to estimate blocked projection signal in synchronized moving grid-based CBCT system.

A preobject grid can reduce and correct scatter in cone beam computed tomography (CBCT). However, half of the signal in each projection is blocked by the grid. A synchronized moving grid (SMOG) has been proposed to acquire two complimentary projections at each gantry position and merge them into one complete projection. That approach, however, suffers from increased scanning time and the technical difficulty of accurately merging the two projections per gantry angle. Herein, the authors present a new SMOG approach which acquires a single projection per gantry angle, with complimentary grid patterns for any two adjacent projections, and use an interprojection sensor fusion (IPSF) technique to estimate the blocked signal in each projection. The method may have the additional benefit of reduced imaging dose due to the grid blocking half of the incident radiation. The IPSF considers multiple paired observations from two adjacent gantry angles as approximations of the blocked signal and uses a weighted least square regression of these observations to finally determine the blocked signal. The method was first tested with a simulated SMOG on a head phantom. The signal to noise ratio (SNR), which represents the difference of the recovered CBCT image to the original image without the SMOG, was used to evaluate the ability of the IPSF in recovering the missing signal. The IPSF approach was then tested using a Catphan phantom on a prototype SMOG assembly installed in a bench top CBCT system. In the simulated SMOG experiment, the SNRs were increased from 15.1 and 12.7 dB to 35.6 and 28.9 dB comparing with a conventional interpolation method (inpainting method) for a projection and the reconstructed 3D image, respectively, suggesting that IPSF successfully recovered most of blocked signal. In the prototype SMOG experiment, the authors have successfully reconstructed a CBCT image using the IPSF-SMOG approach. The detailed geometric features in the Catphan phantom were mostly recovered according to visual evaluation. The scatter related artifacts, such as cupping artifacts, were almost completely removed. The IPSF-SMOG is promising in reducing scatter artifacts and improving image quality while reducing radiation dose.

A Comparison of Outcome between Isobar TTL and Conventional Transforaminal Lumbar Interbody Fusion

Background Spine fusion using posterior instrumentation is currently considered the gold standard in surgical treatment for degenerative disease of the lumbar spine. Treatment-related problems for spinal fusion include stiffness, pseudoarthrosis, mechanical failure, and “adjacent segment disease (ASD).” The Isobar TTL is a form of pedicle screw–based dynamic stabilization (PDS) device. Several studies have shown the Isobar TTL to have good short-term outcomes in terms of fusion and decreasing the incidence of ASD. However, there are limited studies comparing the functional outcomes of the Isobar TTL with the conventional two-level transforaminal interbody fusion (TLIF). Methods This is a retrospective analysis of spine fusion and hybrid fusion cases done for degenerative lumbar disease in our institution during 2009 to 2012. Functional outcomes were measured preoperatively and at 12 and 24 months postoperatively using a 100-scaled visual analogue score (VAS), Oswestry Disability Index (ODI), and Short-Form 36 (SF-36) mental and physical components. Radiographic parameters to assess for ASD were also measured on standing lumbar films. These included disc height at the level of dynamic stabilization, disc height of the adjacent levels, foraminal height of the index level and adjacent levels, adjacent level disc angle, lumbar lordosis, and sacral slope. t test was used to analyze the data. p value of &lt; 0.05 was determined significant. Results A total of 30 cases were studied, 15 of which used Isobar TTL (Scient'x USA, Maitland, Florida, United States) treatment and 15 underwent a two-level TLIF. Mean length of follow-up was 24 months. VAS and ODI scores were slightly lower in the TLIF group at 12 and 24 months postoperatively ( p = 0.86). The SF-36 mental component was 5.51 points higher in the Isobar TTL group at 12 months post-op but was closer to TLIF values by the end of 24 months ( p = 0.8). SF-36 physical component was higher in the TLIF at both 12 ( p = 0.91) and 24 months ( p = 0.37). Disc height showed deterioration in both groups at 12 months postoperatively with a greater reduction in height in the Isobar TTL group ( p = 0.71). Disc angle was better preserved in the Isobar TTL group with an improvement of 1.3 and 0.61 degrees at 12 and 24 months, respectively. Lumbar lordosis was better preserved in the TLIF group with an increment of 1.36 degrees at 12 months ( p = 0.3) and 2.56 degrees at 24 months ( p = 0.77). The Isobar TTL group showed an initial reduction in lumbar lordosis by 3.4 degrees. This improved by 1.49 degrees at the end of 24 months. Among the radiographic parameters, only sacral slope was found to have a significant difference between the Isobar TTL and TLIF groups (mean difference 5.53, p = 0.03). Operation time was longer by 90.83 minutes in the Isobar TTL group ( p = 0.09). The duration of hospital stay was the same for all the patients with an average of 8.83 ± 5.71 days ( p = 0.94). Conclusions The Isobar TTL is a valid treatment option in the management of degenerative lumbar disease. Short-term results of the Isobar TTL are comparable to a two-level conventional TLIF in terms of functional and radiographic outcomes.

Effect of percutaneous kyphoplasty vs.open reduction and internal fixation on lumbar biomechanical function of adjacent vertebrae in rabbits with osteoporosis

Objective To research the changes of lumbar biomechanical function of rabbit model after open reduction and internal fixation and percutaneous kyphoplasty(PKP). Methods New Zealand rabbits were ovariectomized to establish osteoporosis through model, model was successful in 42 cases, divided into two groups, 21 rats in group A, be for open reduction and internal fixation operation,21 rats in group B underwent PKP operation, to observe the changes of the two groups, the model of vertebral compression bending and maximum load experiment content,change of bone mineral density(BMD),change of average height and the sagittal Cobb angle of the vertebral body after operation. Results Two groups of rabbit model after PKP(group B) and open reduction and internal fixation operation(group A), the vertebral bearing pressure ability has been significantly improved compared with before operation, the difference was statistically significant(P 0.05), 18 months after the operation of anterior vertebral height by the average preoperative(38.81±4.12)% and(80.17±8.38)% recovery percent in group B, sagittal Cobb angle by preoperative(30.13±4.27)°recovered to the(8.69±2.41)°.Group B with BMD, vertebral height and Cobb angle measurement value changes compared with the group A, the difference has statistical difference(P< 0.05). Conclusion Compared with open reduction and internal fixation operation, PKP can better improve vertebral body and adjacent vertebral kyphosis angle,significant bearing pressure, PKP is safe and effective in the treatment of osteoporosis, worthy of promotion. Key words: Open reduction and internal fixation; Percutaneous kyphoplasty; Vertebral fracture; Biomechanics; Rabbit

Using a Parallel Spatial/Angular Agglomeration Multigrid Scheme to Accelerate the FVM Radiative Heat Transfer Computation—Part I: Methodology

A parallel spatial/angular agglomeration multigrid scheme is developed to accelerate the finite-volume method (FVM) for the computation of radiative heat transfer in absorbing, emitting, and scattering gray media. The multigrid scheme is based on the solution of the radiative transfer equation (RTE) with the full approximation scheme (FAS) on successively coarser spatial and angular resolutions, derived from the initial finest ones through the fusion of the adjacent control volumes and control angles, respectively. The numerical tests reveal the improvement of efficiency employing the aforementioned technique, especially in cases considering scattering media and reflecting boundaries.