length difference
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Micromachines ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 64
Author(s):  
Yinzhi Zhao ◽  
Jingui Zou ◽  
Peng Zhang ◽  
Jiming Guo ◽  
Xinzhe Wang ◽  
...  

The global navigation satellite system (GNSS)-based multi-antenna attitude determination method has the advantages of a simple algorithm and no error accumulation with time in long endurance operation. However, it is sometimes difficult to simultaneous obtain the fixed solutions of all antennas in vehicle attitude determination. If float or incorrect fixed solutions are used, precision and reliability of attitude cannot be guaranteed. Given this fact, a baseline-constrained ambiguity function method (BCAFM) based on a self-built four GNSS antennas hardware platform is proposed. The coordinates obtained by BCAFM can replace the unreliable real-time kinematic (RTK) float or incorrect fixed solutions, so as to assist the direct method for attitude determination. In the proposed BCAFM, the baseline constraint is applied to improve search efficiency (searching time), and the ambiguity function value (AFV) formula is optimized to enhance the discrimination of true peak. The correctness of the proposed method is verified by vehicle attitude determination results and baseline length difference. Experimental results demonstrate that the function values of error peaks are reduced, and the only true peak can be identified accurately. The valid epoch proportion increases by 14.95% after true peak coordinates are used to replace the GNSS-RTK float or incorrect fixed solutions. The precision of the three attitude angles is 0.54°, 1.46°, and 1.15°, respectively. Meanwhile, the RMS of baseline length difference is 3.8mm.


2021 ◽  
Vol 16 (3) ◽  
pp. 11-18
Author(s):  
T. B Kruglova ◽  
Tatyana N. Kiseleva ◽  
L. A. Katargina ◽  
N. S. Egiyan ◽  
A. S. Mamykina ◽  
...  

BACKGROUND: Relevant keratometric and biometric indicators are necessary for intraocular lens (IOL) power calculation, which is difficult to verify in young children. AIM: Evaluation of the accuracy of various ultrasound methods and optical biometry for axial length measurement in young children with congenital cataracts. MATERIAL AND METHODS: Forty-six children (74 eyes) with congenital cataracts (43 eyes) and pseudophakia (31 eyes) at the age of 6 months to 4 years were examined. Various methods measured the axial length: ultrasound A-scan under general anesthesia by US-4000, ultrasound B-scan without general anesthesia by Voluson E8, and optical biometry by AL-Scan in cases of transparent optics. RESULTS: The greater axial length difference was observed between A-scan and optical biometry (less by 0,78 mm) than between B-scan and optical biometry (more by 0,27 mm). The median axial length difference between A-scan and B-scan was equal for infants and young children with congenital cataracts (0,525 mm and 0,535 mm, respectively). CONCLUSION: Axial length should be measured by different methods in young children with their further comparison to obtaining more accurate biometric indicators for IOL power calculation. The decrease of 12 mm in axial length, which occurs during the A-scan, can lead to errors in the IOL calculation of 36 diopters and unplanned refraction in the long-term period.


2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Matthias Luger ◽  
Sandra Feldler ◽  
Antonio Klasan ◽  
Tobias Gotterbarm ◽  
Clemens Schopper

Abstract Background Correct reconstruction of hip offset (HO) and leg length are important for clinical–functional outcome and patient satisfaction in total hip arthroplasty (THA). The morphology of the proximal femur can pose a risk for increased leg length difference (LLD) in cementless straight-stem THA. We therefore wanted to evaluate, if this is also applicable in THA with a cementless meta-diaphyseal short stem. Methods In a retrospective study, 106 patients (index surgery 2014–2019) with unilateral THA and a morphologically healthy hip as a reference (Kellgren–Lawrence ≤ 1) were included. The same cementless short stem with meta-diaphyseal fixation and cementless press-fit cup was implanted. The proximal femur was rated by Dorr’s classification, and subgroups were formed afterward. Measurements were carried out on preoperative and 3 months postoperative anterior–posterior radiographs of the pelvis. Kruskal–Wallis test, Fisher’s exact test and binary logistic regression were performed to evaluate the influence of the anatomical shape on postoperative leg length difference and offset reconstruction. Results The Dorr type did not show any significance influence on LLD (p = 0.532), or postoperative difference in femoral offset (p = 0.243), acetabular offset (p = 0.106) and hip offset (p = 0.698). Stem alignment (p = 0.705) and canal fill indices (CFI I: p = 0.321; CFI II: p = 0.411; CFI III: p = 0.478) were also without significant differences. Logistic regression did not show any significant increased risk for a LLD ≥ 5 mm or ≥ 10 mm as well as HO ≥ 5 mm or ≥ 10 mm. Conclusion Reconstruction of hip offset and postoperative leg length difference is not negatively influenced by Dorr type, canal flare index, cortical index and canal-to-calcar ratio in cementless short-stem THA. Implant positioning and canal fill are also not negatively affected by the anatomical shape of the proximal femur. Level of evidence: Level IV.


Author(s):  
Sang-Yoon Lee ◽  
Young-Min Noh

Background: This study was performed to identify the incidence of screw in-type lateral anchor pull-out in patients older than 60 years who underwent rotator cuff repair for large to massive rotator cuff tears.Methods: This study reviewed 25 patients older than 60 years who were diagnosed with large to massive rotator cuff tear and underwent arthroscopic rotator cuff repair in our hospital from March 2017 to February 2021. Preoperative tear size (anterior to posterior, medial to lateral) was measured via preoperative magnetic resonance imaging (MRI), and the re-tear rate was evaluated at 3 months via MRI. All 25 patients underwent MRI scanning on postoperative day 1 and at 3 months after surgery. The change of lateral row anchor position was measured in axial views on MRI images. The change of anchor position was measured postoperative day 1 and 3 months after surgery by MRI and statistically compared according to bone mineral density (BMD), sex, and number of lateral anchors. Results: Two consecutive MRIs (postoperative day 1 and 3 months) in 25 patients were compared. Anchor pull-out occurred in six patients during 3 months (6.7%), and the mean pull-out length difference was 1.56 mm (range, 0.16–2.58). There was no significant difference in the number of pull-out anchors, degree of pull-out difference, or the re-tear rate by comparing BMD (A, BMD≤-2.5; B, BMD>-2.5), sex, or number of anchors used in each surgery (C, two anchors; D, three anchors) (p>0.05). Conclusions: Pull-out of screw in-type lateral anchors was observed in very few patients (6.7%), and the mean pull-out length difference was negligibly small (1.56 mm) in our study. The screw in-type lateral anchor seems to be a decent option without concern of anchor pull-out even in elderly patients (>60 yr).


2021 ◽  
Vol 23 (5) ◽  
pp. 375-380
Author(s):  
Maurizio De Pellegrin ◽  
Désirée Moharamzadeh ◽  
Giacomo Placella ◽  
Vincenzo Salini

Klippel-Trenaunay syndrome is a rare congenital malformation which may be associated with macrodactyly. The main problem is the need for custom-made shoes. We describe the case of a female newborn affected by Klippel-Trenaunay syndrome, with a larger and longer right foot; the difference increased progressively and, at 5 years of age, the right foot was 50% larger and 38% longer than the left one. Due to the progression of the deformity, reduction surgery was advised to reduce the foot’s width. Resection of the second ray and 2nd cuneiform was performed. The result was excellent and there were no complications during a 10-year follow-up period with a decrease of width and length difference to 10% and 4%, respectively, in comparison to the contralateral foot. There were no gait anomalies. Abnormal foot width and length represented the main problems and guided the surgical strategy. Second ray resection was effective, without complications and with a good long-term functional outcome. Possibility of wearing fashionable conventional shoes without insoles was achieved to the patient’s satisfaction


2021 ◽  
Vol 3 (2) ◽  
pp. 90-93
Author(s):  
Silvia Ari Agustina ◽  
Reni Merta Kusuma

Background: Emotional closeness is very important for physical growth, emotions and intelligence of babies. The benefit of doing Yoga is to create physical and mental health as well as creating a balance. Research on the effect of baby yoga on infant growth is still limited. The purpose of this study was to determine the effect of yoga on the baby's body weight and lengthMethods: The research method used is quasi-experimental design with the Pre-Post-test Control Group Design method. This study involved 36 samples of infants who had nutritional problems. Which were divided into 2 groups with 18 samples each. The treatment was carried out for 2 months, and 4 treatments were carried out monthly. The statistical test used is paired sample T-Test dan independent T-Test.Results: The statistical test result of paired sample T-Test for Baby Yoga treatment significantly affected the baby's weight and body length with p value = 0.000. The results of the Independent T-Test, the difference in body weight between the baby yoga group with growth and development stimulation was known to be p 0.05 (p = 0.012), there was a difference in weight gain between baby yoga and growth and development stimulation. However, for differences in body length difference test, showing a value of p 0.05 (p = 0.150), the results in body weight and body length difference between the treatment of baby yoga with growth and growth stimulation showed that there was no significant difference between the provision of baby yoga with growth and growth stimulation to increase body length.Conclusion: There is a weight difference between baby yoga treatment and growth stimulation, but no significant difference for body length.


PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0255793
Author(s):  
Wei Liu ◽  
Suling Wang ◽  
Kangxing Dong ◽  
Tiancai Cheng

For staged multi-cluster fracturing, methods for controlling perforation friction to adjust the flow distribution of each cluster can effectively promote the uniform extension of multiple fractures but lacks a fast and quantitative optimization method for different perforation parameters of each cluster. By establishing a numerical model of single-stage three-cluster flow-limited fracturing under stress-seepage coupling, and based on the response surface optimization method, fully considering the impact of perforation parameters interaction among three perforation clusters, according to the regression equation fitted under the global response, the rapid optimization of perforation parameters of segmented multi-cluster fracturing model is realized. The results show that: in determining the three factors of the study, it is found that there is an obvious interaction between the number of intermediate cluster perforations and the number of cluster perforations on both sides, the number of cluster perforations on both sides and the diameter of intermediate cluster perforations, the response surface optimization method gives the optimal perforation parameter combination of three clusters of fractures under global response; When the perforation parameters were combined before optimization, the fracture length difference was 32.550m, and the intermediate perforation cluster evolved into invalid perforation cluster, when the perforation parameters were combined after optimization, the fracture length difference was 0.528m, the three perforation clusters spread uniformly, and there are no invalid clusters. At the same time, the regression equation under the response is optimized before and after the comparison between the predicted value of the equation and the actual simulation value. It is found that the estimated deviation rate of the equation before optimization is 1.2%, and the estimated deviation rate after optimization is 0.4%. The estimated deviation rates are all less, and the response regression equation based on the response surface optimization method can quickly optimize the perforation parameters. The response surface optimization method is suitable for the multi parameter optimization research of formation fracturing which is often affected by many geological and engineering factors. Combining with the engineering practice and integrating more factors to optimize the hydraulic fracturing parameters, it is of great significance to improve the success rate of hydraulic fracturing application.


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