Associations between facet tropism and vertebral rotation in patients with degenerative lumbar disease

Background Vertebral rotation and facet tropism are very common in various lumbar degenerative diseases. Facet tropism means the presence of asymmetric angles on both sides of the facet joints. Studies have shown that facet tropism contributes to lumbar degenerative disease, and also inevitably leads to the asymmetry of movement and the imbalance of force, which may be possible to rotate the vertebral body. The aim of this study was to explore the correlation between lumbar vertebral rotation and facet tropism in patients with lumbar degenerative diseases. Methods A total of 198 patients with lumbar degenerative diseases from 2018 to 2019 were enrolled. Five hundred and seventy vertebral rotation angles and 1140 facet angles were measured. The vertebral bodies are divided into non-rotation group (Group A) and rotation group (Group B) with the vertebral rotation angle of 3° as the boundary. The information including gender, age, BMI (body mass index), bone mineral density, history of smoking, drinking, hypertension, diabetes, diagnosis, segment distribution, and degree of facet degeneration were also counted. Using inter-class correlation coefficients (ICC) to test the reliability of measurement results. Univariate and multivariate logistic regression analysis were used to analyze the relationship between vertebral rotation and facet tropism. Results The consistency of the ICC within the groups of the observers is above 0.8, with good agreement. The results of univariate analysis showed that facet tropism was significantly different between group A and group B (OR (odds ratio) = 3.30, 95% CI = 2.03–5.35, P < 0.0001). Other significant factors were included as adjustment variables into the multivariate regression model. Three models were analyzed separately (Model 1: non-adjusted. Model 2: adjust for age; facet degeneration; Model 3: adjust for age; disease distribution; segment distribution; facet degeneration). The results showed that after adjusting the confounders, the correlation between facet tropism and vertebral rotation did not change (Model 1: OR = 3.30, 95% CI = 2.03–5.35, P < 0.0001; Model 2: adjusted OR = 2.87, 95% CI = 1.66–4.97, P = 0.0002, Model 3: adjusted OR = 2.84, 95% CI = 1.56–5.17, P = 0.0006). Conclusion Current research demonstrates that there is an association between vertebral rotation and facet tropism, suggesting that vertebral rotation may also have a certain degree of correlation with lumbar degenerative diseases.

Construction and analysis of a three-channel numerical control ring-spinning system for segment colored yarn

At present, there have been a significant number of studies of segment colored yarn, and the majority of these studies have made considerable progress, which has made the types and styles of segment colored yarn more abundant. However, the problem that exists in the segment colored yarn is its relatively few kinds of color, which greatly limits its flexibility and diversity in commercial applications. To address the above problems, a multi-channel computer numerical control (CNC) ring-spinning machine was developed, and a digital spinning mechanism with online regulation of the forming linear density and blending ratio was constructed through the developed three-channel drafting mechanism and its driving and controlling system; the spinning mechanism of segment colored yarn using the time-varying three-channel drafting ratio to the spinning time-varying three-colored fiber blending ratio was established by implementing a coupling algorithm for co-drafting of multi-channel roving; the forming process and algorithm of segment colored yarn, which is used to solve the blending ratio of three colored fibers and the drafting ratio of three-channel roving based on segment color, was constructed through the digital color mixing model and the design of segment color of yarn. According to the above mechanism, three rovings with two color combinations of cyan, magenta, yellow and cyan, magenta, black were used to design and spin segment colored yarns with three, five and seven colors, respectively. By testing and analyzing the linear density, twist, unevenness, surface hairiness and tensile properties of the segment colored yarn, it is proved that the timing control of the three-channel drafting ratio based on CNC ring spinning can achieve the timing control of the blending ratio of the three colored fibers, which is beneficial to the spinning of segment colored yarn with color segment distribution.

A Stress Distribution of Thin Rectangular Steel Wall Under a Uniform Compression

The stress distribution of a steel wall is important in the determination of its shear capacity, e.g. under a wind load or an earthquake load. Since the wall has also to simultaneously carry the gravity load, the influence of this uniform vertical load on the stress distribution is relevant. For a simple-supported thick and square wall, a stress distribution in a cosine form was adequate. However, for an extremely thin wall, a cosine distribution is no longer valid, especially in the post-buckling condition. In this work a three-segment distribution is proposed, i.e. at both edge segments a cosine distribution from edge stress to buckling stress and in the middle segment a constant distribution of buckling stress. To evaluate the proposed distribution, a finite element model using the software ANSYS/LS-DYNA is developed. This model has been verified using the results obtained from own experiments and works done by others. The results show that the proposed stress distribution is able to describe the behavior of thin walls for different aspect ratios and slendernesses. The cosine distribution and the effective width model are also discussed.

Effect of hydrophobic core on the electrophoresis of a diffuse soft particle

Electrophoresis of a diffuse soft particle with a charged hydrophobic core is considered under the weak field and low charge density assumptions. The hydrophobic surface of the core is coated with a diffuse polyelectrolyte layer (PEL) in which a gradual transition of the polymer segment distribution from the impenetrable core to the surrounding electrolyte medium is considered. A mathematical model is adopted to analyse the impact of the core hydrophobicity on the diffuse soft particle electrophoresis. The mobility based on the present model for the limiting cases such as bare colloids with hydrophobic core and soft particles with no-slip rigid cores are in good agreement with the existing results. The presence of PEL charges produces the impact of the core hydrophobicity on the soft particle mobility different from the corresponding bare colloid with hydrophobic surface in an electrolyte medium. The impact of the core hydrophobicity is subtle when the hydrodynamic screening length of the PEL is low. Reversal in mobility can be achieved by tuning the core hydrophobicity for an oppositely charged core and PEL.

A SEGMENT-BASED APPROACH FOR DTM DERIVATION OF AIRBORNE LIDAR DATA

With the characteristics of LIDAR system, raw point clouds represent both terrain and non-terrain surface. In order to generate DTM, the paper introduces one improved filtering method based on the segment-based algorithms. The method generates segments by clustering points based on surface fitting and uses topological and geometric properties for classification. In the process, three major steps are involved. First, the whole datasets is split into several small overlapping tiles. For each tile, by removing wall and vegetation points, accurate segments are found. The segments from all tiles are assigned unique segment number. In the following step, topological descriptions for the segment distribution pattern and height jump between adjacent segments are identified in each tile. Based on the topology and geometry, segment-based filtering algorithm is performed for classification in each tile. Then, based on the spatial location of the segment in one tile, two confidence levels are assigned to the classified segments. The segments with low confidence level are because of losing geometric or topological information in one tile. Thus, a combination algorithm is generated to detect corresponding parts of incomplete segment from multiple tiles. Then another classification algorithm is performed for these segments. The result of these segments will have high confidence level. After that, all the segments in one tile have high confidence level of classification result. The final DTM will add all the terrain segments and avoid duplicate points. At the last of the paper, the experiment show the filtering result and be compared with the other classical filtering methods, the analysis proves the method has advantage in the precision of DTM. But because of the complicated algorithms, the processing speed is little slower, that is the future improvement which should been researched.

A SEGMENT-BASED APPROACH FOR DTM DERIVATION OF AIRBORNE LIDAR DATA

With the characteristics of LIDAR system, raw point clouds represent both terrain and non-terrain surface. In order to generate DTM, the paper introduces one improved filtering method based on the segment-based algorithms. The method generates segments by clustering points based on surface fitting and uses topological and geometric properties for classification. In the process, three major steps are involved. First, the whole datasets is split into several small overlapping tiles. For each tile, by removing wall and vegetation points, accurate segments are found. The segments from all tiles are assigned unique segment number. In the following step, topological descriptions for the segment distribution pattern and height jump between adjacent segments are identified in each tile. Based on the topology and geometry, segment-based filtering algorithm is performed for classification in each tile. Then, based on the spatial location of the segment in one tile, two confidence levels are assigned to the classified segments. The segments with low confidence level are because of losing geometric or topological information in one tile. Thus, a combination algorithm is generated to detect corresponding parts of incomplete segment from multiple tiles. Then another classification algorithm is performed for these segments. The result of these segments will have high confidence level. After that, all the segments in one tile have high confidence level of classification result. The final DTM will add all the terrain segments and avoid duplicate points. At the last of the paper, the experiment show the filtering result and be compared with the other classical filtering methods, the analysis proves the method has advantage in the precision of DTM. But because of the complicated algorithms, the processing speed is little slower, that is the future improvement which should been researched.

Monomer Reactivity Ratios and Chain Segment Distribution for AM/2-EHA Copolymer

A new copolymer of acrylamide (AM) and Isobutane-Ethylhexyl acrylate (2-EHA) was synthesized as profile control agent by free radical copolymerization. The copolymer composition obtained by element analysis method led to determination of reactivity ratio by employing YBR calculative method. The result indicated that the reactivity ratios of AM and 2-EHA were 0.856and 0.592 respectively. The chain segment distribution of copolymer was investigated from reactivity ratio and the microstructure of copolymer molecule was analyzed. The results showed that the ratios in feed can hardly change the chain segment distribution. The proportion of 1M1 decreased with the increase of AM in feed. AM and 2-EHA had a tendency to alternate in copolymer chain when f1=0.286~0.375. The monomer which had a low ratio in feed inserted in copolymer chain with 1M chain segment and the other monomer was separated evenly. It can help to study copolymerization for AM and 2-EHA for industrial production in mass.